A handbook of cryptogamic botany

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CRYPTOGAMIC BOTANY

PRINTED BY

SPOTTISWOODE AND CO., NEW-STREET SQUARE
LONDON

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A HANDBOOK

OF

CRYPTOGAMIC BOTANY

BY

ALFRED W. BENNETT, M.A., B.Sc, F.L.S.

LECTURER ON BOTANY AT ST THOMAS'S HOSPITAL

AND

GEORGE MURRAY, F.L.S.

SENIOR ASSISTANT, DEPARTMENT OF BOTANY, BRITISH MUSEUM
AND EXAMINER IN BOTANY, GLASGOW UNIVERSITY

A v 3

WITH 378 ILLUSTRATIONS

LONDON

LONGMANS, GREEN, AND CO.

AND NEW YORK : 15 EAST 16'" STREET
1889

All rights reserved

V

PREFACE.

IN presenting to the botanical public this ' Handbook of Cryptogamic
Botany,' the result of the labour of several years, the authors are deeply
sensible of its inevitable defects. In traversing so wide a field, it is im-
possible that a single worker, or even two, can be practically acquainted
with more than a comparatively small portion of it. It is necessary,
therefore, to consult a literature, the extent of which, even for a single
year, is appalling, and in which it is often difficult to distinguish between
trustworthy and untrustworthy observations. The attempt has, notwith-
standing, been made by the authors to acquaint themselves with the
contents of every important publication of recent years bearing on
Cryptogamic Botany, and issued in English, French, German, Italian,
or Latin. It is beyond hope but that inaccuracies have crept in, or
that observations which should have been noted have escaped attention.
We shall be grateful to workers and writers who will inform us of any
such inaccuracies or omissions, and especially to those who will kindly
supply us, with a view to future editions, with copies of papers containing
records of new and original observations or theories. Those relating to
Vascular Cryptogams, Muscinese, Algae, and Schizophycese should be
directed to Mr. Bennett ; those relating to Fungi, Mycetozoa, and Schizo-
mycetes to Mr. Murray ; these being the portions of the work actually
written respectively by each of us, although we hold ourselves severally
responsible for the whole contents of the volume.

So rapidly are facts accumulating, and new views of affinity being
promulgated, that it may be necessary to change one's opinion on some
points even in the interval between the printing of the earlier and Jater
sheets of a volume like this ; and this must be held to account for any

*
vi PREFACE

slight discrepancies that may be apparent between the general scheme
of classification contained in the Introduction, and the details as carried
out in the work itself.

We have also to acknowledge the permission given by the publishers
of the following , works for electros to be taken from the illustrations
contained in them, viz. : — De Bary, ' Comp. Morph. und Biol. der Pilze,
Mycetozoen, und Bacterien,' and 'Vorlesungen iiber die Bacterien';
Sachs, ' Lehrbuch der Botanik ' ; Goebel, ' Grundziige der Systematik ' ;
Luerssen, ' Die Kryptogamen ' ; Schenk, ' Handbuch der Botanik ' ;
Zopf, ' Die Spaltpilze ' : Hauck, ' Die Meeresalgen ' ; Reinke, ' Lehrbuch
der Botanik ' ; Thome, * Lehrbuch der Botanik ' ; Le Maout et Decaisne,
'Traite General de Botanique'; Solms-Laubach, ' Einleitung in die
Palaeophytologie.'

Of the remaining illustrations, many have been taken from nature ;
others have been copied from the illustrations of previous works, especi-
ally from Cooke's * British Freshwater Algae ' ; and for others we have
to thank the courtesy of the Councils of the Royal and Linnean
Societies, and the publishers of the 'Annals of Botany.'

In those branches of Cryptogamic Botany which have not been
the immediate object of our own researches, we have freely consulted
experts in these several departments, and have received from all the
greatest kindness and most valuable assistance. In particular we wish
to express our obligations in this respect to Mr. W. CARRUTHERS, Pres.
L.S., F.R.S. ; Mr. J. G. BAKER, F.R.S. ; Professor F. O. BOWER, F.L.S. ;
Dr. R. BRAITHWAITE, F.L.S. ; Mr. E. M. HOLMES, F.L.S. ; and Mr. G.
C. KAROP, F.R.M.S.

ALFRED W. BENNETT,

December, 1888. 6 PARK VILLAGE EAST, LONDON, N.W.

GEORGE MURRAY,

BRITISH MUSEUM (NATURAL HISTORY),
CROMWELL ROAD, LONDON, S.W.

CONTENTS.

PAGE

INTRODUCTION ...... i

FIRST SUBDIVISION: VASCULAR CRYPTOGAMS . . . 10

HETEROSPOROUS VASCULAR CRYPTOGAMS . . . .21

CLASS I. RHIZOCARPE^E . . . . 21

,, II. SELAGINELLACE.E . . . . . 38

ISOSPOROUS VASCULAR CRYPTOGAMS . . . • • 53

CLASS III. LYCOPODIACE/E . . . . . -53

,, IV. FILICES . . . . .... 64

„ V. OPHIOGLOSSACE.E . . . . -95

,, VI. EQUISETACE.*: . . . . . IOO

FOSSIL VASCULAR CRYPTOGAMS . . . . . .114

SECOND SUBDIVISION: MUSCINE^E . . . . . 132

CLASS VII. MUSCI ....... I36>

,, VIII. HEPATIC^ . . . . . . . 156

FOSSIL MUSCINE^E . . . . . . .172

THIRD SUBDIVISION: CHARACE^ . . . ' . . 173

CLASS IX. CHARACE/E . . . . . -173

FOSSIL CHARACE^: . . . . . . . 183

FOURTH SUBDIVISION : ALG& . . 184

CLASS X. FLORIDE^: . . . , . . 191

,, XI. CONFERVOIDE/E HETEROGAM/t . . . . 2IQ

,, XII. FUCACE.E . . . . . . 228

,, XIII, PHjEOSPORE/E ...... 237

,, XIV. CONJUGAT/E . . . . . . 258

,, XV. CONFERVOIDE/E ISOGAM^ . ... . 272

,, XVI. MULTINUCLEAT.K . . . . . 280

,, XVII. CCENOBIE/E . . . . . .29!

FOSSIL Al.G.-E . . . . . . . 303

viii CONTENTS

FIFTH SUBDIVISION : FUNGI ...... ^05

GROUP I. PHYCOMYCETES . . . . . . . 323

CLASS XVIII. OOMYOETKS ...... 323

,, XIX. /AV.OMYCETES . . . . . 335

GROUP II. SPOROCARPE.*; ...... 353

CLASS XX. ASCOMYCETES . . . . . . 353

,, XXI. UREDINE^E ...... 383

„ XXII. BASIDIOMYCETES . . . . . . 388

SIXTH SUBDIVISION: MYCETOZOA . . 401

CLASS XXIII. MYXOMYCETES . . . . . 40!

,, XXIV. ACRASIE/E ...... 405

SEVENTH SUBDIVISION: PROTOPHVTA . . . . 407

GROUP I. SCHIZOPHYCK i: ...... 408

CLASS XXV. PROTOCOCCOIDE.?: . . . . 409

,, XXVI. 1)1 ATOM ACE.*: . . . . . -4*9

,, XXVII. CYAXOPHYCE/E . . . . . . 426

GROUP II. SCHIZOMYCETES ... . . 449

CLASS XXVIII. SCHIZOMYCETES . . . . . 449

INDEX .......... 457

Errata

Page ii, line 22, for oophore read oophyte

,, n, ,, 2-2, for sporophoie TV#</ sporophyte

,, 122, description of fig. 94, for Haulea read Haivlea

„ 186, line 10, for CCENOBI^ read CCENOBIE.B

,, 187, ,,, 12, for Mesocarpece, Des»iidiece read Mcsocarpacccr, DestiiidiaceeF

„ 187, lines 19, n,for Desmidieat read Desmidiaceae

,, 187, line 26, for Mesocarpeae read Mesocarpaceae

,, 190, ,, 4, for Desmidieae read Desmidiaceae

,, 208, last line, for HYPX/TCACE.*: read HYPNEACE.-K

,, 209, line i, for Hypnaea read Hypnea

,, 209, ,, A,, for Rytiphlaea read Rytiphloea

213, description of fig. 191, line i, for corymlosa read corymbljera
250, ,, ,, ,, 223, ,, 2, for propagules rt'tf*/ sphace les
280, line 6 from bottom, for Dasycladaecea read Dasycladaceae

296, last line, ior polyhedra read polyhedrie

311, description of fig. 271, line i, for Lib. read de By.

313, ,, ,, ,, 275, ,, i, for Portulacea read Portiilaca

319', line 3, omit full stop after Johow

326, description of fig. 287, line 3, also last line of page, for Portulace<e read Portnlacn

335, line 2, insert comma after Pythium

343» » J5 from bottom, for Tremellini read Tremellineae

381, ., -iT,,for Barenetski read Baranetzki

HANDBOOK

TO

CRYPTOGAMIC BOTANY.

INTRODUCTION.

No general handbook to Cryptogamic Botany has appeared in the
English language since the Rev. M. J. Berkeley's in 1857. Since then
this department of botanical science has gone through little less than
a revolution. Not only has the number of known forms increased
enormously, but additions of great importance have been made to our
knowledge of structure by the use of the microscope, and to the genetic
connection of different forms by the careful following out of the life-
history of particular species. The present work is an attempt to bring
within the reach of botanists, and of the public generally who are in-
terested in the study of nature, an acquaintance with the present state of
our knowledge in this branch of science. It is not intended to replace
in any way the numerous excellent handbooks or monographs which
exist of special families or groups. Its scope is quite different. Neglect-
ing the minor differences by which genera, or in many cases even
orders, are distinguished from one another, the aim of the authors has
been to bring before the reader the main facts of structure, of develop-
ment, and of life-history, which mark the larger groups, contrasting them
with one another, and referring only to the broader lines of demarcation
within those groups. It is hoped that the work will be found useful to
the beginner as well as to the more advanced student.

One great difficulty in our work has been to observe a due propor-
tion in the space allotted to the different groups ; and this has been in-
creased by the necessity for a very different mode of treatment in the
higher and the lower forms. Of the Vascular Cryptogams — more nearly
allied in many respects to Phanerogams than to the lower Cryptogams —
our knowledge is, with some exceptions, as minute and exhaustive as that

2 INTRODUCTION

of Fknvering Plants ; and it is improbable that any living forms remain
to be discovered differing in any material point of structure from those
'ready known. Here, therefore, we are able to discuss systems of
classification which claim something like finality ; and the difficulty of
t'ru compiler of a handbook is the enormous amount and the minute
detar of the material to his hand, from which he has to cull those por-
tions which seem suitable for his object. In order not to extend this
portion of the work beyond due limits, it has been necessary frequently
to practise rigid compression — beyond, probably, what many of our
readers specially interested in these groups would have desired. The
same 'remarks apply, to a large extent, to the Muscineae. But in the
Thaltophytes, and especially in the lower Algae and Chlorophyllous
Protophyta, the case is very different. From the extremely minute size
of many of these, and the much smaller extent to which they have been
studied, new forms are constantly being discovered, and important ad-
ditions are yearly being made to our knowledge of their life-history and
of their structure. It is highly probable that among these groups, as
well as in some of the orders of Fungi, forms will yet be discovered
which cannot be assigned to any type at present known, gaps in the life-
history of many species will yet be filled up, and organisms hitherto
placed in widely separated families will ultimately be found to be phases
in one cycle of development. We have therefore, in this branch of our
subject, brought before our readers every fact of importance known to
us which is vouched for by observers in whom we have cpnfidence ;
and the classification here submitted is a purely tentative one. In the
Algae, the Fungi, and the Protophytes, we do not attempt an exhaustive
enumeration of orders or families which shall include every known
organism, but describe in detail only those types which are of greater
importance, and of which our knowledge is more complete.

Something must be said on the classification adopted. In the Vascular
Cryptogams and in the Muscineae this proceeds on generally recognised
lines, in which there is not much room for difference of opinion. But
a very different treatment seemed necessary of the Thallophytes, and of
the relationship to one another of the Algae and Fungi, and of the
different orders within each of these groups. Here the systems pro-
posed are almost as numerous as the original investigators, and it has
been necessary to choose that which appeared to the authors to bring
together those organisms which are most nearly related to one another.
Whether these two familiar terms represent a natural bifurcation in the
classification of the lower organisms, is a question which has been
very variously answered by different observers and theorisers. About
fifteen years ago a system of classification of the Thallophytes was pro-

INTRODUCTION 3

posed, on authority entitled to the highest respect,1 which altogether
abolished the bifurcation into Algae and Fungi. On this system the
sole character made use of in their primary classification was the mode
of reproduction. First came the Protophyta, in which no sexual mode
of reproduction is known, followed by three primary classes (in ascending
order)— the Zygosporeae, Oosporeae, and Carposporeae — distinguished
solely by the degree of complexity of the sexual process. Each of these
four classes was then divided into a series containing chlorophyll and a
series not containing chlorophyll, the former including the organisms
hitherto known as Algae, the latter those hitherto known as Fungi.

In support of this view it was urged, with great plausibility, that,
reproduction being the most important event in the life-history of a
plant, the mode in which this is brought about must become fixed *in each
group by heredity ; while such a subordinate character as the presence
or absence of chlorophyll is seen, in the higher plants, to be entirely
without importance in determining affinity. But a little consideration
will show that it is unsafe to apply the same rule to more highly and to
less highly organised forms. In the higher forms of life the mode of
sexual reproduction becomes, in its main features, absolutely fixed ; and
throughout the vast range of Angiosperms — as in the higher animals —
there is entire uniformity in this respect in all important points ; while
in external morphology, and in the mode in which they obtain their live-
lihood, there is the greatest diversity, even within a narrow circle of
affinity. In the animal kingdom we may point, as an illustration of this
law, to the existence of such a family as the Cetacea among Mammalia;
among flowering plants we have only to consider such phenomena as
the occurrence of parasitism, insectivorous habits, or the suppression of
chlorophyll, in individual genera dispersed through a large number of
natural orders. Even in subsidiary characters connected with the pro-
cess of reproduction there is not the uniformity that might have been
expected. While such an apparently subordinate point as the number
of cotyledons in the embyro is so constant as to give its name to primary
divisions of Phanerogams, a character which might have been supposed
to be much more important (but which, it is instructive to observe, is
connected with the mode in which the germinating embryo receives its
nutriment)— viz. the presence or absence of endosperm— is not always
constant, even within narrow limits. The first necessity of a nascent
organism is to live ; and hence it is not surprising to find that in the
lower forms of life the one character which remains most constant within
wide circles of affinity is the mode of life. In the course of development

1 See Sachs's Text-book of Botany, 2nd English edition, p. 244.

4 INTRODUCTION

of the higher forms nature may be said to have tried a variety of
experiments in the mode of reproduction ; on the whole there is a con-
tinual advance, but still by no means infrequent fallings back to simpler
modes ; and unless this law of retrogression is taken into account, any
system of classification must be pro tanto imperfect and misleading.

If these considerations have any weight, it is not surprising that,
although the system of classification of Thallophytes above alluded to
has been adored by a few authorities in this country and on the
Continent, it has not met with general acceptance. The adoption of its
leading principle, that ' in each class Fungi have diverged as ramifications
from various types of Algae,' l is seen to lead to such startling results as
the collocation in the same class of Spirogyra and Mucor, of Volvox and
Peronospora, of Callithamnion and Agaricus. It may, on the contrary,
be safely asserted that several of the most important groups among
Fungi (take, for example, the Uredineae and the Basidiomycetes) display
no traces of genetic affinity with any known class of Algae ; and if, on the
other hand, we have forms like Saprolegnia and Chytridium among Fungi,
or Leptothrix and Beggiatoa among Protophyta, which betray strong indi-
cations of a degraded affinity with groups of Algae, this by no means
contradicts the general law that Fungi as a class form an altogether
independent series.

Retrogression may take the form of the suppression of either the
vegetative or the reproductive organs ; and wherever you have one of
these sets of organs displaying strong development, while the other set
of organs is very feeble or altogether wanting, you have prima facie
evidence of retrogression. Of this examples will be given in the
sequel.

While, therefore, we adopt the Protophyta as a primary class, with
the general limits proposed by Sachs, we have no hesitation in reverting
to the time-honoured division of the higher Thallophytes into the two
great groups of Algae and Fungi.

The classification of Fungi adopted is that of de Bary, consisting of
a main series (called the series of the Ascomycetes), composed as follows :
(i) Peronosporeae (with Ancylisteae and Monoblepharis), (2) Sapro-
legnieae, (3) Mucorini or Zygomycetes, (4) Entomophthoreae, (5)
Ascomycetes, (6) Uredineae; and of divergent groups as follows: (7)
Chytridineae, (8) Protomyces and Ustilagineae, (9) Doubtful Ascomycetes
(Saccharomyces, &c.), (10) Basidiomycetes.

The groups 1-4 are Phycomycetes, and 7 and 8 of the second series
go with them ; while 9 stands in relation to 5, and 10 to 6; and they are

1 Sachs's Text-book, p. 244, foot-note.

INTRODUCTION . 5

so considered together in the linear series in which they come in the
book. The Phycomycetes approach the Algae (Chlorophyceae) very
nearly j and the other groups of Fungi bear a relation to the Phycomy-
cetes which seems to negative any supposition of their independent
connection with algal forms.

One other point had to be decided, whether to commence at the
bottom or at the top of the series. Had our purpose been to construct
theoretically a genealogical tree for the lower forms of vegetable life, the
former course must necessarily have been pursued, and in the laboratory
there is no doubt much to be said in favour of proceeding from the
simple to the more complicated types. But to the general student, ' from
the known to the unknown ' is a very sound principle. And, among
flowerless plants, not only are the higher types far the best known to the
ordinary observer, but they are also those about the life-history of which
we have the greatest certainty of knowledge. We have been confirmed
in our belief of the correctness of this decision by observing that in the
last edition of Huxley and Martin's ' Elementary Biology ' these authors
have (in the zoological section) abandoned the ascending for the
descending order.

The question of terminology is one of the greatest stumbling-blocks
to the student of cryptogamy. Not only are new terms being constantly
introduced, many of them quite needlessly or from an erroneous idea of
structure ; but some that are in continual everyday use are employed
in different senses by different writers of repute. The first requisite in
a terminology, after accuracy, is simplicity ; and to this end we have,
wherever possible, used anglicised instead of Latin and Greek forms.
Many of the terms which we employ throughout this volume — such as
sporange, archegone, antherid, ccenobe, sclerote, epiderm, &c. — will probably
be accepted at once ; and it seems strange that the awkward and un-
couth foreign forms of these words should have held their ground so
long. With others there will no doubt be greater hesitation ; but we
hope to see all, or nearly all, of the anglicised forms we have used gradu-
ally introduced into all English works on cryptogamic botany, and the
same principle possibly extended in other cases where we have not
ventured to apply it.

A striking instance of the uncertainty which still surrounds crypto-
gamic terminology is afforded by the various senses in which different
writers use the everyday term ' spore.' Le Maout and Decaisne and
Asa Gray speak of spores as ' the analogues of seeds ; ' Berkeley de-
scribes the unfertilised oospheres of Fucus as spores ; Vines includes
under the term all reproductive cells produced either asexually or
sexually ; while Sachs defines a spore as a reproductive cell produced

6 INTRODUCTION

either directly or indirectly by an act of fertilisation, reserving the term
' gonidium ' for those which are produced without any previous act of
impregnation. It is obvious that one practical defect of this last sug-
gestion is that it may necessitate a perpetual change of terminology as
our knowledge advances. Every fresh extension of the domain of sexual
fecundation — and it is probable that many such will, take place — will
involve the removal of a fresh series of reproductive cells from the cate-
gory of gonidia to that of spores, even though they may not be the
immediate result of an act of fertilisation. Again, if the spores of ferns
and mosses are the indirect result of impregnation, it is difficult to say
why the term should not ultimately include all reproductive bodies
whatever, except the spores of the ' apogamous ferns ' with which Farlow
and de Bary have recently made us acquainted, and of other similar
abnormal productions, which are certainly not the result of impreg-
nation, direct or indirect.

It seems a sounder principle — and is certainly more convenient to
the student— to base a system of terminology on facts which can be
confirmed by actual observation, rather than on unproved hypotheses.
We propose, therefore, as the basis of our terminology, to restore the
term spore to what has been in the main hitherto its ordinary significa-
tion, and to restrict its use to any cell produced by ordinary processes of
vegetation, and not directly by a union of sexual elements, which becomes
detached for the purpose of direct vegetative propagation. The spore may
be the result of ordinary cell-division or of free-cell-fornlation. In
certain cases (zoospore) its first stage is that of a naked primordial mass
of protoplasm. In rare instances it is multicellular, breaking up into a
number of cells (poly spore, composed of merispores, or breaking up into
sporids).

The simple term spore will, for the sake of convenience, be retained
in Muscineae and Vascular Cryptogams ; but in the Thallophytes it will
generally be used in the form of one of those compounds to which it so
readily lends itself, expressive of the special character of the organ in
the class in question. Thus, in the Protophyta we have chlamydo-
spores ; in the Myxomycetes, sporangiospores ; in the Saprolegnieae and
many Algae, zoospores ; in the Uredineae, teleutospores, cecidiospores,
uredospores, and sporids ; in the Basidiomycetes, basidiospores ; in the
Ascomycetes (including Lichenes), ascospores, poly spores, and merispores ;
in the Diatomaceae, auxospores ; in the CEdogoniaceae, androspores ; in
the Florideae, tetraspores ; and others belonging to special groups.
The cell in which the spores are formed will, in almost all cases, be
called a sporange ; and this term will be compounded in the same way
as spore.

INTRODUCTION 7

In describing the heterosporous Vascular Cryptogams it is usual to
speak of the spores which give rise to the female prothallium and those
which give birth to antherozoids as ' macrospores ' and ' microspores '
respectively. The first of these terms is doubly objectionable : firstly,
etymologically, the proper meaning of /xa/cpo's being not 'large/ but 'long ; '
and secondly, from the close similarity in sound of the two terms, an
inconvenience, especially in oral instruction, which every teacher must
have experienced. Seeing that the correct and far preferable terms
megaspore and microspore are used by Berkeley, Areschoug, Carpenter,
and others, it is difficult to understand how ' macrospore ' can ever have
got into general use ; and these terms, together with megasporange and
microsporange, will be used in the following pages. For similar reasons
megazoospore is always used instead of 'macrozoospore.'

The male organs of fecundation are so uniform in their structure
throughout Cryptogams that very little complication has found its way
into their terminology. The cell or more complicated structure in which
the male element is formed is uniformly known among Cormophytes as
well as Thallophytes as an antherid ; the fecundating bodies are almost
invariably naked masses of protoplasm, provided with vibratile cilia,
endowed with apparently spontaneous motion, and bearing the appro-
priate name of antherozoids or ' spermatozoids.' The former of these is
perferable for two reasons ; from its etymological connection with
antherid, and because the use of terms compounded from ' sperm' should,
for reasons to be detailed presently, be avoided for male organs. In only
two important groups, Florideae and Ascomycetes, are -the fecundating
bodies destitute of vibratile cilia and of spontaneous motion : in the
former case they are still usually termed ' antherozoids ; ' in the latter
' spermatia,' and their receptacles ' spermogonia.' In order to mark the
difference in structure from true antherozoids, it is proposed to designate
these motionless bodies in both cases pollinoids ; the term ' spermogone '
is altogether unnecessary, the organ being a true antherid.

A satisfactory terminology of the female reproductive organs presents
greater difficulties, from the much greater variety of structure, and the
larger number of terms already in use. The limits we have placed to
the use of the term ' spore ' and its compounds require the abandonment
of ' oospore ' for the fertilised ovum or oosphere in its encysted state
(enclosed in a cell-wall), anterior to its segmentation into the embryo ;
and this is the most important change involved in the terminology of
the present volume.

In devising a term which shall include all those bodies which are
the immediate result of impregnation, it was necessary to take two
points specially into account. Firstly, the term must be capable of

£ INTRODUCTION

defence on etymological grounds ; and secondly, it must, like 'spore,' be
suited for ready combination. After much consideration we have de-
cided on adopting the syllable sperm. No doubt the objection will
present itself that the Greek o-Trep/za, like the Latin ' semen,' while origi-
nally meaning the ultimate product of fertilisation, came afterwards to
signify the male factor in impregnation ; and hence, in zoology, terms
derived from these roots are used for the male fertilising bodies. But
the objection applies to a much smaller extent to phyto-terminology,
and the use in the proposed sense of the syllable * sperm ' is justified by
the universal employment in phanerogamic botany of such terms as
' gymnosperm,' 'angiosperm,' 'endosperm,' and 'perisperm.' Ofcrypto-
gamic terms, where the syllable is used in the reverse sense, 'sperm-cell,'
for antherozoid or pollen-grain, has never come into general use in this
country ; ' spermatozoid ' is easily replaced by ' antherozoid ; ' ' spermo-
gonium ' is simply a peculiar form of antherid, and ' spermatium ' has
already been referred to. Accepting this term as the least open to
objection of any that could be proposed, it will be found to supply the
basis of a symmetrical system of terminology, which will go far to redeem
the confusion that at present meets the student at the outset of his re-
searches. For the unfertilised female protoplasmic mass the term
oosphere is already in general use ; and, though not all that could be
desired, it is proposed to retain it. The entire female organ before fer-
tilisation, whether unicellular or multicellular, is designated by a set of
terms ending m gone, such as archegone and carpogone, again > following
existing analogy.

The term reproduction itself is often far too vaguely employed by
botanical writers. We propose to limit its use, in accordance with its
etymology, to the production of a new individual, that is, to a process
of impregnation ; all cases of non-sexual multiplication being described
as propagation,

The object of the writer of a handbook is to gather up and to collate
material already existing, winnowing, to the best of his judgment, the
wheat from the chaff. Except, therefore, where original observations
may have been made by the compiler himself, it will contain nothing
new. In compiling from the writings of the original observers it was
thought best, as far as possible, to use their own words, and this will
account for the frequent close resemblance in the following pages of the
descriptions contained to those in such works as de Bary's ' Comparative
Anatomy of the Phanerogams and Ferns,' the * Comparative Morphology
and Biology of the Fungi, Mycetozoa, and Bacteria,' by the same writer,
the scheme of which has been mainly adopted in outline, and Goebel's
'Outlines of Classification and Special Morphology.' Admirable, on

INTRODUCTION 9

the whole, as are the translations of these works by which the Clarendon
Press has enriched English scientific literature, it is the original work
rather than the translation that we have in all cases followed. We wish
here to express the great obligation under which we lie to these writers,
and to acknowledge the extent to which we have borrowed from them.
In the chapter on Fossil Vascular Cryptogams we have, to a considerable
extent, followed Graf zu Solms-Laubach's excellent ' Einleitung in die
Palaeophytologie,' though with some modifications. To the description of
each group or family we have appended a bibliography of the researches
on which that description is founded ; these having again been consulted,
wherever possible, in the original language.

IO

FIRST SUBDIVISION.
VASCULAR CRYPTOGAMS.

THE Vascular Cryptogams include all the highest forms of cryptogamic
life, and constitute a well-marked group of plants intermediate between
the Gymnosperms, or lowest division of Flowering Plants, and the lower
or Cellular division of Flowerless Plants. From the former they differ
mainly in the mode in which fertilisation is effected ; from the higher
forms of the latter in the much greater differentiation of tissues. The
term ' vascular ' Cryptogams is, however, strictly speaking, correct only
to a limited degree. Although the arborescent and fruticose species
display as well-marked a differentiation of their tissues as Flowering
Plants, into epidermal tissue, ' vascular ' bundles, and fundamental tissue,
and the bundles consist of distinct xylem and phloem (without any
intermediate cambium, as in Gymnosperms), it is only rarely, as in that
group of Flowering Plants, that the xylem is composed of vessels in the
true sense of the term.

The Vascular Cryptogams and the highest families of Cellular
Cryptogams are distinguished from Flowering Plants by an obvious
Alternation of Generations between Sexual Generation or Oophyte, and
Non-sexual Generation or Sporophyte. The former is a small and
purely cellular structure, usually of very temporary duration, the purpose
of which is to bear the sexual organs of reproduction, male antherids
and female archegones, the structure of which is uniform in all essential
characters throughout the class, and which are borne on a cellular ex-
pansion, the prothallium. This prothallium may be either monoecious
or dioecious — that is, the male and female organs may be borne on the
same or on different prothallia. The act of fertilisation consists in the
impregnation of an oosphere, a naked mass of protoplasm contained
within the central cell of the archegone, by one or more antherozoids,
minute masses of protoplasm endowed with spontaneous motion by
means of vibratile cilia, which escape from the cells of the antherid
and penetrate to the central cell of the archegone. The immediate
result of the impregnation of the oosphere is that it invests itself

VASCULAR CRYPTOGAMS 11

with a cell-wall of cellulose, and thus becomes an oosperm, wrhich
develops into the embryo, and finally into the sporophyte, which
is often of great size and extended length of life. It is this that is com-
monly known in popular language as the Fern, Club-moss, &c. On it
are produced, without any process of fertilisation, the spores, which are
always single cells, protected by two or three coats, and giving rise on
their part, when they germinate, to the oophyte. This is the cycle of
development in the Isosporous families of Vascular Cryptogams. In the
Heterosporous families there are produced (always on the same plant)
two different kinds of spore, differing very greatly in size — larger mega-
spores and smaller microspores. The former produce female prothallia,
that is, those which bear archegones only ; the latter male prothallia,
bearing antherids only, or even antherozoids, without the intervention of
a male prothallium or antherid. The spores are always endogenous
structures, produced by free-cell-formation within a spore-case or
sporange, which again, in the heterosporous families, is a megasporange
or a microsporange, according as it contains megaspores or microspores.
The sporanges are often collected into groups known as son, and these
may again be enclosed within special chambers, sporocarpsmconceptades.
Various kinds of vegetative propagation, similar to those of Flowering
Plants, also occur on both oophyte and sporophyte ; and in certain ex-
ceptional cases either the oophore or the sporophore may be entirely
suppressed, constituting the phenomena of apogamy and apospory re-
spectively. These will be described especially under Ferns, where they
are of the most common occurrence.

It may be useful in this place to compare the structure of the organs
of reproduction and the phenomena of impregnation in Vascular
Cryptogams with those of Phanerogams, and to endeavour to trace the
requisite homologies,1 although these cannot be fully understood with-
out some knowledge of the details of structure described under the
separate families. It has been usual to compare the pollen-grain of
Phanerogams with the antherozoid of Vascular Cryptogams ; but this is
not strictly accurate. The essence of the act of fecundation consists in
the coalescence of the protoplasmic contents of an active (male) and of
a passive (female) cell. The protoplasmic endoblast or cell-contents in
each case must, therefore, be homologous ; that is, the antherozoid with
the protoplasmic contents of the pollen-grain which, in Flowering Plants, is
brought into contact with the embryonic vesicle by means of the pollen-

1 Hofmeister was the first to point out these homologies in his Vergleich. Unters.
iiber Keimungu.s.iv. der hoheren Kryptogamen (see the Ray Society's translation, On
the Germination, &*<:., of the Higher Cryptogatnia, p. 438). They have since been
traced out more completely by Hanstein, Celakovsky, and others.

12 VASCULAR CRYPTOGAMS

tube ; or probably the more correct homology is that of the nucleus of
the antherozoid with the * generative ' nucleus of the pollen-grain. The
most important difference between Cryptogams and Phanerogams lies
in the mode in which this contact between the male and female elements
is brought about. In Flowering Plants it takes place by the penetration
into the embryo-sac, through the micropyle of the ovule, of the extension
of the inner coat of the pollen-grain known as the pollen-tube, excited
into activity by the viscid secretion of the stigma. The pollen-grain
has therefore in the first place ' to be conveyed from the anther to the
stigma ; and the various parts of the flower of Flowering Plants are all more
or less concerned, directly or indirectly, with arrangements for facilitating
the conveyance of pollen. In Flowerless Plants, on the contrary, contact
between the male and female elements is effected by the protoplasmic
contents escaping from the male cells and coming directly into contact
with the oosphere in consequence of an independent power of motion
imparted to these naked masses of protoplasm (antherozoids) by the
vibratile cilia with which they are provided. This impregnation always
takes place in water or moisture, and no external agency is needed to
bring it about. Hence the absence from all Flowerless Plants of any
conspicuous compound organ analogous to the flower of Phanerogams.
The true homology of the pollen-grain of Phanerogams appears to be
with the microspore of the heterosporous Vascular Cryptogams, notwith-
standing the fact that the contents of the microspore break up into a
number of antherozoids, each capable of impregnating an oosphere :
while the pollen-grain, as a rule, emits only a single pollen-tube. Here,
as in other phenomena, we are guided to the true homology by compar-
ing the highest Cryptogams with the lowest Phanerogams, the Gymno-
sperms, which form a connecting link between them and Angiosperms.
In all Gymnosperms, as in some Angiosperms, the pollen-grain is
divided into several cells, only one of 'which (very much larger than all
the rest) emits a short pollen-tube. The large fertile cell in the pollen-
grain of Gymnosperms corresponds to the larger fertile portion of the
microspore of Selaginellaceae, to the entire contents of the microspore
of Marsileaceae, to the terminal cell of the germinating filament in
Salviniaceae, and to the antherid of the isosporous Vascular Cryptogams.
In Angiosperms the sterile cells of the pollen-grain of Gymnosperms
appear to be sometimes entirely suppressed, and the pollen-grain
becomes unicellular. The contents of the pollen-grain of Angiosperms,
together with the intine or inner coating of the grain, are therefore
homologous with the antherid of Cryptogams. Seeing that the motile
antherozoids have to be conveyed to the oosphere through the medium
of water, it is convenient for both antherid and archegone to be freely

VASCULAR CRYPTOGAMS

exposed to the action of moisture at the time of maturity. Hence, in
all the isosporous Vascular Cryptogams, by far the largest portion of the
product of germination of the hermaphrodite spore is the cellular tissue
or prothallium (reduced to a comparatively small size in the Lycopo-
diacese and Ophioglossaceae), on which are borne both the antherids and
the archegones. In the heterosporous Salviniaceae the male prothallium
is reduced to a simple unseptated germinating filament ; and in
Marsileaceae it altogether disappears. In Selaginellaceae it takes the form
of the small sterile cells at one extremity of the microspore ; in Gymno-
sperms, of the sterile cells of the pollen-grain ; in Angiosperms it is
almost entirely suppressed. The contents of the pollen-grain corre-

FlG. I.— I., male catkin of Zamia. (Cycadeae).
II. III., antheriferous scale and pollen-sacs.

FIG. 2.— Peltate scale of Equisetunt,
with sporanges sg. (After Sachs.)

spending to the antherozoids, the pollen-grain itself becomes homologous
with the microspore, the pollen-sac or anther-cell to the microsporange.
Even in external appearance the pollen-sacs of Coniferae and Cycadeae
bear a striking resemblance to the sporanges of some Vascular Crypto-
gams. The modes of formation of the pollen-grains within the pollen-
sac and of spores within the sporange, from an original archespore, are
identical in their main features.

Turning now to the female organs of reproduction, we must trace
the homology of these back from the product of the union of the two
elements, which in all the higher plants, whether flowering or flowerless,
may be termed the oosperm, developing later into the embryo. In

14 VASCULAR CRYPTOGAMS

Flowering Plants this is the product of the action of the contents of the
pollen-grain on the protoplasmic embryonic or germinal vesicles ; in the
higher Flowerless Plants, of the action of the antherozoid on the oosphere,
or protoplasmic contents of the central cell of the archegone. The
naked masses of protoplasm known as the germinal vesicles ( or perhaps
rather that one only which is ultimately fecundated) are therefore un-
questionably homologous with the naked mass of protoplasm known as the
oosphere. In Vascular Cryptogams the central cell which contains the
oosphere is a portion of an archegone which is borne on a prothallium
resulting from the germination of a spore or of a megaspore, as the case
may be. To understand the homologies with the higher Phanerogams
we must again have recourse to the intermediate Gymnosperms. In

FIG. 4.— Female prothallium of Mar-
silea, with archegone a and oo-
spheres. (After Hanstein.)

FIG. 3.— Fertilisation of Abies (Coniferae). /,
pollen-grains ; PS, pollen-tube ; e, embryo-
sac ; c, secondary embryo-sac or corpusculum.
(x 60.)

this class the female elements are not directly developed in the in-
terior of the embryo-sac, but within certain chambers produced within
the embryo-sac, the secondary embryo-sacs or ' corpuscula, the homo-
logues of the central cell of the archegone. In connection with them
there have been detected other structures comparable to the neck and
the canal-cells of the archegone. The object of the peculiar structure
of the archegone and the deliquescence of the canal-cells being to facili-
tate the passage of the motile antherozoids to the oosphere, these are
no longer wanted when impregnation is effected by means of a pollen -
tube. The archegone (except the central cell) is therefore reduced to
a rudimentary condition in Gymnosperms, and disappears altogether in
Angiosperms, where the embryonic vesicles are produced directly within

VASCULAR CRYPTOGAMS 15

the embryo-sac, the homologue of the me'gaspore. The nucellus of the
ovule must then be regarded as corresponding to the megasporange ;
but it is difficult to carry the homology further. In Filices and Lyco-
podiaceae an hermaphrodite prothallium usually exposes both kinds of
sexual organ to the action of moisture ; in Equisetaceae we find a normal
differentiation into male and female prothallia, but produced from one
kind of spore only ; in the heterosporous families the differentiation is
carried back to the spores and sporanges, and the female prothallium
is altogether a subordinate product, and never has any separate existence
apart from the megaspore, within which it is more or less concealed,
only that part which bears the archegones being exposed. In Angio-
sperms it has been suggested that we have a rudiment of the female
prothallium surviving in the peculiar ' antipodal cells ' found within the
embryo-sac in certain natural orders ; but the homology is doubtful.
In the Selaginellaceae we find also the rudiments of two other structures
which characterise the ovule of Flowering Plants. The sterile tissue which
occupies the lower part of the megaspore in this order is probably the
first appearance of the endosperm (albumen) which is found in the seed
of a large number of Flowering Plants ; the purpose in both cases being
the same, to provide the embryo with nutritive material during the early
stages of its growth. In all Phanerogams the young embryo is borne
on a longer or shorter pedicel of cellular structure, the suspensor or pro-
embryo, which, again, we find for the first time in the same order of
Cryptogams.

In all the isosporous Vascular Cryptogams the sexual generation or
oophyte has an independent existence distinct from the spore which
produced it ; while in the heterosporous families the prothallium recedes
more and more into the background, existing only within the megaspore ;
and at the same time the male organs or antherids become more rudi-
mentary in structure. In Gymnosperms the female prothallium and the
antherids (as distinct from the antherozoids) have become much reduced,
and in Angiosperms have completely disappeared. While, therefore, in
Characeae alternation of generations disappears by the suppression of
the non-sexual generation which bears the spores, in Phanerogams the
same result is brought about by an exactly opposite process, the sup-
pression of the sexual generation or prothallium with its antherids and
archegones, and the coalescence of male and female elements takes
place within the non-sexually produced embryo-sac of the ovule, which
corresponds to the megaspore.

The life-history and general structure of the various organs in
Vascular Cryptogams may now be described more in detail.

The immediate product of the germination of the spore or megaspore

16 VASCULAR CRYPTOGAMS

is always a prothallium, which is usually a green plate of tissue lying flat
on the soil, very commonly lobed or reniform in shape, sometimes
microscopic, but often quite visible to the naked eye, from £ to \ an inch
in diameter, and constituting, with its organs of reproduction, the oophore,
oophyte, or sexual generation. The prothallium usually disappears as soon
as the non-sexual generation has firmly rooted itself in the soil ; but in
Gymnogramme (Filices) it attains a larger size, and continues its existence
for a considerable time, producing a succession of reproductive organs.
The oophyte never becomes differentiated into stem and leaves, as
in the Muscineae, nor does it contain any vascular tissue. It usually
consists of only a single layer of cells filled with chlorophyll, except a
marginal cushion, where there are several layers. Here it puts out into
the soil numerous colourless elongated cells, the organs of attachment,
or rhizoids,1 among which, or scattered over the whole of the under
surface and margin, are the archegones and antherids. True vegetative
budding takes place but rarely on the prothallium ; but it sometimes,
in certain Filices, exhibits apogamy, the sporophore springing directly
from it, without the intervention of the sexual organs. In some Lyco-
podiacese and in the Ophioglossaceae the prothallium is subterranean,
destitute of chlorophyll, and cylindrical or tuberous. In the Hymeno-
phyllaceae (Filices) it is often filiform. In the isosporous families the
prothallium is most commonly monoecious, less often dioecious. In the
heterosporous families it is far less fully developed. That which arises
from a megaspore is very small, formed within the spore, and at no
period maintains an independent existence ; while that developed
within a microspore is still more rudimentary.

The archegones of Vascular Cryptogams are produced on the pro-
thallium, usually on the under side of the cushion. Each archegone
consists of a swollen basal portion or venter, and a neck, usually composed
of four longitudinal rows of cells ; the venter is buried in the tissue
of the prothallium, the neck alone projecting above it. The arche-
gone originates from a superficial cell of the prothallium, which
divides by a tangential wall into an inner and an outer cell ; the latter
then develops, by further divisions, into the four rows of cells constitut-
ing the neck, which is, therefore, always comparatively short. The
inner cell puts out a protuberance between the neck-cells, which is first
of all separated as the neck-canal-cell, and below it a small portion is
again separated from the lower larger cell as the ventral canal-cell ; the

1 These organs are frequently termed root-hairs ; but it is better to confine this
term to the epidermal appendages (trichomes) of the roots of Phanerogams and of the
sporophyte generation of Vascular Cryptogams, between which and true rhizoids there
is a functional rather than a morphological homology.

VASCULAR CRYPTOGAMS 17

lowermost portion of the lowest cell remains of a comparatively large
size, and is the central cell containing the oosphere. When mature, the
two canal-cells deliquesce into mucilage, which swells up considerably,
drives apart the four apical lid-cells or stigmatic cells of the neck, and
is ejected ; an open canal being thus formed to allow the access of the
antherozoids to the oosphere, which always takes place in moisture, the
ejected mucilage assisting also in this process.

The tf«Mm#rappear as roundish papillae on the margin, or dispersed
over the under surface of the prothallium ; in some cases they are im-
bedded in its tissue. Each antherid consists of a comparatively small
number of cells ; when mature the cell-walls are ruptured under water,
and from each escapes a swarming antherozoid. The antherozoids are
spirally coiled threads of protoplasm, the body of which is formed from
the nucleus of the mother-cell, with a number of fine vibratile cilia
on the anterior coils. There is generally attached to each anthero-
zoid, as it escapes from its mother-cell, a vesicle of protoplasm contain-
ing starch-grains, formed out of the cytoplasm of the mother-cell, which,
adhering to one of its posterior coils, is dragged along with it during its
swarming, but becomes detached before its entry into the neck of the
archegone. In the heterosporous families the antherid is of very simple
structure, and is either produced directly within the microspore, or after
the preliminary formation of a few cells, which must be regarded as a
rudimentary prothallium.

The form and size of the non-sexual generation or sporophyte vary
within very wide limits, from the filmy, moss-like Hymenophyllacese
(Filices) to the arborescent tree-ferns (Filices), and must be described
more in detail under the various families. It arises in the archegone,
from the oosperm or fertilised oosphere. The first effect of impregnation
is that the oosphere invests itself with a cell-wall of cellulose, thus
becoming the oosperm, which then divides into a small number of
undifferentiated cells, in which condition it is known as the embryo. In
the earliest subsequent divisions of the embryo may be recognised the
rudiments of the first root, of the first leaf or cotyledon, and of the apex
of the stem ; while at the same time a lateral outgrowth termed \hefoot
is formed at the bottom of the venter, and draws from the prothallium
the first nourishment for the young plant. The venter at first grows
vigorously, enveloping the embryo, until this latter finally protrudes
free, leaving the foot still attached to it for some time as a nutritive
organ. The primary root soon disappears, and in some Hymenophyl-
laceae, and in Salvinia and Psilotum, is not followed by others ; but in
the great majority of cases other true roots succeed in acropetal suc-
cession, and the prothallium then disappears. The cotyledon always

c

iS VASCULAR CRYPTOGAMS

remains small ; the first stem bends upwards, and other leaves of a
more complicated structure appear on it.

The roots of Vascular Cryptogams usually arise in acropetal succession
on the stem (in some ferns on the leaf-stalk), and branch either mono-
podially or dichotomously. There is never one preponderating root
continuous in a downward direction with the main stem corresponding
to the tap-root in Flowering Plants. They are distinguished from the
roots of Flowering Plants by the lateral roots springing, not from the
procambium, but from the innermost cortical layer of the mother-root.
They are abundantly covered with root-hairs, trichomic formations by
means of which the nutritive materials are absorbed from the soil.
They possess a true root-cap. Salvinia (Rhizocarpeae) and Psilotum
(Lycopodiaceae) are altogether rootless, as also are a few Hymenophyl-
laceae (Filices), the function of roots being performed by underground
branches of the stem.

The degree of development of the stem varies within very wide limits.
In the tree-ferns it is of erect habit, and attains great height and consider-
able thickness. In many herbaceous ferns the internodes of the erect
stem are altogether suppressed, while the underground portion forms an
elongated rhizome. In the existing Lycopodiaceae, and in some Sela-
ginellaceae. the very elongated creeping stem is mainly above ground ;
in the rootless forms, like Psilotum, branches of the stem bending down
into the soil perform the function of roots. In some paludose species
belonging to the Rhizocarpeas the stem is almost entirely suppressed,
and in Salvinia the whole plant floats on the surface of the water. The
mode of branching is either monopodial or dichotomous ; the leaves do
not usually produce buds and branches in their axils, as in Flowering
Plants.

In all the larger species the stem displays a distinct differentiation of
tissues into the three systems, fundamental, epidermal, and 'vascular' or
fascicular. The so-called vascular bundles are closed, like those of Mono-
cotyledons— that is, they contain no formative cambium ; and they are
usually but not always concentric, the phloem portion surrounding the
xylem portion in the form of a phloem-sheath. Each bundle, or a group
of bundles, is again very frequently surrounded by a single layer of
strongly sclerenchymatous cells belonging to the fundamental tissue, the
vascular bundle-sheath, where it encloses a single, or plerome-sheath,
while it surrounds a group of bundles. The prevalent, though not the
exclusive form of thickening in the xylem is that of scalariform tra-
cheides ; true vessels formed from the coalescence of cells are rare ; in
the phloem sieve-tubes are of common occurrence. Potonie holds that
there is no sharp differentiation between the xylem and phloem portions

VASCULAR CRYPTOGAMS 19

of the ' vascular ' bundles of Vascular Cryptogams, and prefers for them
the terms hadrome and leptome respectively. According to Van Tieghem,
the secondary tissues, like those of Flowering Plants, proceed normally
from two concentric generating layers — an external one in the cortex,
forming bark outwardly and secondary cortex inwardly, and an inner one
in the central 'vascular 'cylinder intercalated in the liber and in the xylem
of the primary ' vascular ' bundles, producing secondary liber outwardly
and secondary xylem inwardly. The epiderm is in most cases abun-
dantly provided with trichomic appendages of various kinds.

The size and form of the leaves are extremely various. In Lycopo-
diurn, Selaginella, and some other genera, they are very small, unseg-
mented, and lanceolate, not unlike those of mosses, and form a dense
imbricated clothing to the stem ; in Psilotum they are altogether rudi-
mentary ; in the Equisetaceae they are reduced to divisions or teeth of
a membranous sheath ; in Isoetes (Selaginellaceae), Pilularia (Rhizo-
carpeae), and Phylloglossum (Lycopodiaceae), they are long, narrow, and
awl- shaped. In some ferns the barren and fertile leaves differ from one
another in appearance, and especially in the degree of division of the
lamina. In Salvinia they are of two kinds, one floating on the surface
of the water and entire, the other submerged, very finely divided, and
performing the function of a root ; in Azolla (Rhizocarpeae) they are
floating and bilobed. In some genera of Filices and their allies the
leaves are quite entire ; in the Hymenophyllaceae they are very delicate,
consisting of only a single layer of cells, and in the smaller species
closely resemble those of the foliose Hepaticae ; while in most ferns they
are of considerable (in the tree-ferns of gigantic) size, with well-marked
petiole, rachis, and lamina, and distinguished by the great extent to
which the lamina is divided. In most cases (except the Hymenophyl-
laceae) they are abundantly provided with stomates. The tissue beneath
the epiderm consists of a parenchymatous mesophyll containing abun-
dance of chlorophyll, the portion of which adjacent to the upper
epiderm is frequently developed as palisade-parenchyme. This meso-
phyll is permeated by ' vascular ' bundles or veins, which branch off
from the cauline bundles, and are distinguished, in the majority of ferns,
by their dichotomous mode of branching, in contrast to the reticulate
anastomosing in Dicotyledons, and the parallel arrangement in most
Monocotyledons. Among Gymnosperms a similar arrangement is pre-
sented by Salisburia and Stangeria. The floral metamorphosis of
the leaves of Flowering Plants does not occur in Vascular Cryptogams,
nor their special agglomeration round the organs of reproduction as
in mosses.

The mature sporange, theca, or spore-case, is usually a roundish

c 2

20 VASCULAR CRYPTOGAMS

capsule borne on a stalk, of small size and simple structure. Its morpho-
logical value varies greatly, and will be referred to more particularly
under the separate families. In the majority of Filices the sporanges are
trichomic structures, and are collected into groups or sort, which are
always located in connection with a 'vascular 'bundle on the under side
or margin of the leaf. In the Marattiaceae they spring from a hypo-
dermal mass of tissue. In the Ophioglossaceae a segment of a leaf is
transformed into sporanges. In Selaginella and Lycopodium they
arise from the growing point of the stem above the axil of a leaf. In
Psilotum they are sunk in the extremity of branchlets of a peculiar form.
In the Salviniaceae they are enclosed in receptacles or sporocarps, which
are themselves modifications of divisions of the leaf. The mode of
formation of the spores closely corresponds to that of the pollen-grains in
Flowering Plants. The spore-forming tissue can always be traced back to
a single cell or a row or layer of cells, the archespore, which may be dis-
tinguished at a very early period from the remaining cellular tissue by
the nature of its contents. From this proceeds the sporogenous tissue,
which afterwards becomes the mother-cells of the spores by perfectly
regular divisions, the details of which differ in the different families.
This is surrounded by one or more layers of cells, the tapetal cells or
tapete, and the whole is enclosed in the wall of the sporange, itself
composed of one or more layers of cells. In the heterosporous
families the distinction between megaspores and microspores is manifested
only at a comparatively late period in their development. In the iso-
sporous families the spores are always strictly unicellular, very commonly
elliptical or reniform in shape. The coat always consists of two separ-
able layers — an outer cuticularised exospore, often elevated into warts or
other prominences ; and an inner endospore, composed of cellulose, which
bursts through the exospore on germination, producing the germ-filament,
which develops by cell-division into the prothallium. In the mega-
spores of the heterosporous families these are further protected on the
outside by a third separable, greatly hardened layer, the epispore. The
mode in which the spores escape from the sporange differs in the dif-
ferent families.

A purely vegetative mode of propagation by means of gemmae or
bulbils borne on the sporophyte occurs especially in Filices and
Equisetacese ; on the oophyte vegetative propagation is less common.

The classification of Vascular Cryptogams is attended with consider-
able difficulty. None of the systems as yet produced have much claim
to be regarded as natural ; and, until some doubtful points are cleared
up connected with fossil forms which may be links between existing
families, the primary distinction into Heterosporous and Isosporous

VASCULAR CRYPTOGAMS 21

Vascular Cryptogams is so convenient, that we have decided to adhere
to it, without dogmatising as to its permanent retention. In the
boundaries of the families, again, there is equal room for diversity of
opinion. Whether to retain the Psiloteae under Lycopodiaceae, and
the Isoeteae under Selaginellaceae, and whether to regard the trueFilices,
the Marattiaceae, and the Ophioglossaceae as constituting one, two, or
three classes, are points on which there is much to be said in favour of
classifications different from that which we have decided to adopt.

LITERATURE.

Thuret— (Zoospores and Antherids) Ann. Sc. Nat., vol. xiv., 1850, p. 214; and
vol. xvi., p. 5.

Hofmeister— Germination, Development, and Fructification of the Higher Crypto-
gams, Ray Soc., 1862.

Schacht — Die Spermatozoiden, Braunschweig, 1864.

Dippel— (Fibrovasc. Bundles) Ber. Deutsch. Naturf. u. Aerzte, 1865.

Nageli u. Leitgeb — (Root) Nageli's Beitr. z. wiss. Bot., 1867.

Kny— (Prothallium) Sitzber. Ges. Naturf. Freunde, Berlin, 1868.

Millardet— (Prothallium) 1869.

Russow — Vergleich. Unters. , Petersburg, 1872.

Janczewski - (Archegone) Bot. Zeit., 1872,- p. 418.

Goebel- (Sporangia) Bot. Zeit., 1880 and 1881.

Sadebeck— Die Gefasskryptogamen, 1880.

Prantl -Morphologic der Gefasskrypt. , 1881.

Van Tieghem- Bull. Soc. Bot. France, 1883, p. 169.

Potonie— (Vase. Bundles) Jahrb. Bot. Gart. Berlin, 1883.

Leitgeb - (Spores) Ber. Deutsch. Bot. Gesell., 1883, p. 246.

Celakovsky — Pringsheim's Jahrb. f. wiss. Bot., xiv., 1884, p. 291.

Bower — (Leaf) Proc. Roy. Soc., xxxvii., 1884, p. 61.

Rabenhorst— Crypt. Flora Deutschland, Vase. Crypt., by Luerssen, 1884-88.

De Bary— Comparative Anatomy of Phanerogams and Ferns, 1884.

Klein— (Dehiscence of Sporange) Bull. Soc. Bot. France, 1884, p. 292.

Leclerc du Sablon — (Spores) Ann. Sc. Nat., vol. ii., 1885, p. 5.

Campbell— (Antherozoids) Ber. Deutsch. Bot. Gesell., 1887, p. I2O.

Baker -Handbook to Fern Allies, 1887.

• HETEROSPOROUS VASCULAR CRYPTOGAMS.
Class I.— Rhizocarpeae.

The Rhizocarpeae or Hydropterideas constitute a class composed of
only a small number of genera, none of which includes more than a few
species. They grow submerged in or floating on water, and derive their
name from the circumstance that the non-sexual organs of propagation
are produced in the radicular region, or near the base of the leaves.

22

VASCULAR CRYPTOGAMS

The spores are of two kinds, one of which is many hundred times
larger than the other. The larger spores, or megaspores, produced in
megasporangeS) are female ; the smaller spores, or microstores, produced

F/G. 5. — Pihila ria globulifera. L., with FIG. 6. — Marsilea quadrifolia L., with fructifi-
fructification, natural size. (After cation, natural size, and fructification en-

Luerssen.) larged. (After Luerssen.)

in microsporanges, are male. The megaspore is not completely spherical,
but has a distinct apical protuberance, which at the period of maturity
is enveloped in a thick firm layer termed the epispore, formed by the

RHIZOCARPE^E 23

hardening of mucilage derived from the disorganisation and deliques-
cence of a portion of the contents of the sporange. The female prothal-
lium is formed within the apical papilla of the megaspore, and is
exposed by the bursting of the enveloping epispore. It never completely
frees itself from the megaspore, and is usually altogether destitute of
chlorophyll. It bears one or more archegones, differing from one
another in smaller points of structure in the different genera. The
microspores do not give birth to a male prothallium, nor even to
antherids, in the sense in which the terms are employed elsewhere in

A

FIG. 7. — Salvinia natans L. A and B natural size, the latter with two aerial leaves and sub-
merged fertile leaves ; C, two sporocarps, slightly magnified and diagrammatic, one con-
taining a few megasporanges, the other a large number of microsporanges ; Z>, section of
empty sporocarp, slightly magnified. (After Luerssen.)

Vascular Cryptogams ; the contents divide more or less directly into the
parent-cells of the antherozoids, which, accompanied by peculiar vesicles
attached to them, reach and impregnate the oosphere contained in the
central cell of the archegone.

The external form of the sporophyte or non- sexual generation varies
widely in the different genera. The growth of both stem and root is
always the result of successive divisions from a single apical cell. The
stem is extremely abbreviated in Salvinia (Schreb.) and Azolla (Lam.) ;
procumbent and creeping in Marsilea(L.)andPilularia(L.). It is traversed

VASCULAR CRYPTOGAMS

by closed concentric ' vascular ' bundles, each surrounded by its bundle-
sheath, and the branching is always monopodial. The roots — except in
Salvinia, which is rootless — are fibrous, are furnished with a root-cap,
and branch monopodially. The leaves also vary greatly in form. In
Pilularia they are erect, cylindrical, and setiform : in Marsilea (L.) the
lamina consists of several distinct leaflets at the extremity of a more or
less elongated petiole. In both these genera the vernation is circinate.
In Azolla the leaves are deeply bifid. Salvinia is remarkably hetero-
phyllous. While the majority of the leaves retain an ordinary leaf-like

habit, others develop into coriaceous
scutiform structures, while others again
divide into a number of capillary
segments, which perform the function
of roots, and at the same time bear the
non-sexual propagating organs.

The fructification is of a more
complicated structure than in other
classes of Vascular Cryptogams. In
Salvinia it springs from the lower teeth
of the submerged leaves ; in Azolla
from the pendent section of the deeply
bipartite leaf, or rather of one particular
leaf; in Pilularia it stands beside and
beneath the leaves ; in Marsilea (L.) on
the under side of the petiole, or of the
base of the leaf itself. The Rhizo-
carpese are always monoecious, the two
kinds of sporange being produced on
the same individual, and usually in
close proximity. The structure and
degree of complexity of the fructifi-
cation differ in the different genera.
The sporanges are always associated
together in groups. Each of these groups, known as asorus or sporocarp,
is a closed capsule-like chamber, which is of epidermal or trichomic
origin, its wrall or indusium, often considerably hardened, being an
extension of the epiderm. Each sporocarp is regarded by Celakovsky
as the homologue of the integumented ovule of Flowering Plants. In
the Salviniaceae the sporocarp is unilocular; in the Marsileaceae it is
plurilocular, and the wall indurated into a hard shell. Each sporocarp
may contain sporanges of one kind only or of both kinds ; in the former
case male and female sporocarps are often associated together in

FIG. 8. — Salvinia natans L. Young
plant still attached to the prothal-
lium^r, and megaspore 5^. f>, scuti-
form leaf ; / and //, first and second
leaves ; L1 and L", later aerial, and
iv, submerged leaf of the first whorl.
(After Pringsheim, x 20.)

RHIZOCARPE^: 25

groups. The megasporanges are often considerably larger than the
microsporanges.

In the early stages of their development no difference is exhibited
between the megasporanges and microsporanges. In both cases the
sporange originates in a papilla placed on the placenta, which divides
first into an upper and a lower cell, the latter developing, by repeated
transverse septation, into the pedicel, the former into the body of the
sporange, and dividing ultimately into a large central tetrahedral
archespore, surrounded by a layer which almost immediately breaks up
into two layers of tapetal cells or mantle-layers. The archespore further
divides into sixteen spore-mother-cells, and each of these into four
special spore-cells arranged tetrahedrally. A difference is now mani-
fested according as the sporange is to develop into a mega- or a micro-
sporange. In the latter case each of the sixty-four cells develops into
a microspore, while the tapetal cells become disorganised, and changed
into the frothy mucilage which subsequently hardens and encloses the
spores. In the former case only one of the sixty-four cells develops
into a megaspore, growing rapidly at the expense of the others, and
ultimately filling up the cavity of the sporange. The remaining sixty-
three spore-cells, as well as the tapetal cells, become disorganised, and
deliquesce into a frothy mucilage which envelops the ripe megaspore,
ultimately hardening into the epispore, which splits to allow the emergence
of the prothallium. In Azolla the mucilage of the microsporanges forms
the peculiar massulce which will be described later.

A more detailed description requires the division of the Rhizocarpese
into the two orders Salviniacece. (Salvinia and Azolla) and Marsileacece.
(Marsilea and Pilularia), which are, perhaps, not in reality very nearly
related to one another.

ORDER i. — SALVINIACECE.

The female prothallium of Salvinia is formed within the apical papilla
of the megaspore. The protoplasm in this papilla appears to separate from
that of the rest of the spore, and then breaks up by free-cell-formation
into several portions, which remain for a time unclothed with cellulose ;
subsequently they secrete cell-walls, and form a tissue, which breaks
through the cell-wall of the papilla, and forces its way through the epi-
spore, which splits into a three-lobed body. The prothallium, when it
first emerges from the epispore, has a somewhat triangular form, with an
elevated ridge along its median line, and two wing-like appendages,
subsequently forced apart by the growth of the embryo, which hangs
down on each side of the spore. It contains a considerable amount of

26

VASCULAR CRYPTOGAMS

chlorophyll, but never loses its connection with the megaspore, even
after the commencement of the germination of the sporophyte. The
first archegone makes its appearance on the elevated dorsal ridge of the
prothallium, and subsequently two others are formed, one on each side
of the first. If one of these is fertilised no more archegones are pro-
duced, and the prothallium ceases growing. But if no impregnation
has taken place the prothallium continues to grow, and produces from
one to three additional rows, each consisting . of from three to seven
archegones. In Azolla the prothallium has the form of a slightly convex

disc, consisting, in its central part,

Prfi # of several layers of cells, at the

margin of only one. A single
archegone is first formed, near the
centre of the prothallium. If this

FIG. 9. — Salvinia natans. Longitudinal section
through megaspore and prothallium. a, wall
of sporange ; l>, epispore, formed of hardened
mucilage ; c, coat of spore ; d, diaphragm
separating prothallium from spore-cavity ; pr,
prothallium ; m, neck of archegone ; /, 77,
first two leaves of embryo ; s, scutiform leaf
or cotyledon. (After Pringsheim, x 70.)

FlG. 10. — Archegone of Sahnnia. natans
in three stages, a, b, c, divisions in the
neck-cells ; d, neck-canal-cell ; <?, oosphere ;
h, neck-cells. (After Pringsheim, x 150.)

is fertilised, no others are formed ; if not, it is followed by a few others.
The archegone of Salvinia is a nearly globular cavity, its venter being
completely buried in the tissue of the prothallium. The central cell is
at first somewhat elliptical, its axis lying obliquely to the surface of the
prothallium. Its apex is at first covered by four cells belonging to the
epiderm, arranged in the form of a cross. Each of these four neck-cells
divides by transverse septa into a row of three cells, the four rows thus
forming a short neck. The large central cell now elongates upwards
-and forces its way between the lowermost four cells of the neck, and its

RHIZOCARPE&

27

conical point becomes cut off by a septum, forming the neck-canal-cell.
Below this a second very small portion of the central cell is again cut off
to form the ventral canal-cell, so that the canal now consists of two
cells. These two cells become transformed into mucilage, which escapes
by forcing apart the four apical or stigmatic cells, leaving an open canal
In the meantime the protoplasm of the large basal portion of the central
cell has become transformed by contraction into the oosphere. The
archegone is now ready for impregnation, the antherozoids reaching the
oosphere through a funnel-shaped depression in the epispore and the
open canal. After fertilisation the canal again closes up by the expan-
sion of the stigmatic cells. The
archegone of Azolla resembles that
of Salvinia in all essential points.

The male prothallium of Salvinia
is reduced to a mere rudiment. The
microspores lie imbedded in a mass
of hardened, granular, frothy mucilage,
formed by the disorganisation of the
tapetal cells. They do not escape
from this mucilage, but the endospore
of each develops into a tubular fila-
ment which pierces through the muci-
lage and the wall of the sporange.
The extremity of this filament which
projects outside the sporange is
curved, and becomes cut off by a
septum. The lower and larger of the
two cells thus'formed is regarded as
a rudimentary prothallium • the termi-
nal cell, which again divides into two,

as a rudimentary antherid. The protoplasm of each of the two
antheridial cells divides into four, and each of these eight masses of
protoplasm escapes as an antherozoid. Each antherozoid is a corkscrew-
like coil of protoplasm, bearing vibratile cilia of great length at its'
broader extremity. To the same extremity is attached a vesicle, com-
posed of a portion of the protoplasm of the antheridial cells which
was not used up in the formation of the antherozoids, and which does
not leave the antherozoid during the period of its 'swarming.'

The development of the multicellular embryo from the fertilised
oosperm has been very carefully followed out in Salvinia. The first
segmentation is by a nearly vertical wall (at right angles to the surface
of the prothallium) into two somewhat unequal portions, each of which

FIG. ii. — Salvinia natans. A, micro-
sporange, with microspore-tubes st.
(x ioo.) £, microspore-tube (x 200)
with closed, C with empty antherid.
D, antherozoids ( x 600). (After
Pringsheim.)

28 VASCULAR CRYPTOGAMS

again divides by a septum nearly at right angles to the first one. Further
divisions then take place. Out of the posterior of the first two segments
(the one immediately beneath the mouth of the archegone) is formed
the foot of the young plant, by which it is attached to and derives its
nutriment from the prothallium. From the anterior of these two seg-
ments is derived a peculiar foliar structure, differing from all the subse-
quent leaves, the cotyledon or scutiform leaf, by the growth of which the
terminal bud of the stem becomes directed downwards. No root what-
ever is produced. Azolla is stated to have a second cotyledon. Both
stem and root (in Azolla) are developed from a single apical cell, which
is rounded in front and pointed below. The primary meristem-layers
are differentiated, as in Flowering Plants, into plerome, periblem, and
dermatogen.

The mature sporophyte differs considerably in appearance in the two
genera, but always floats on the surface of the water. The very short
stem is erect or horizontal, and the branching of both stem and root (in
Azolla) is monopodial. The root, stem, and leaf-stalk are each traversed
by a single concentric ' vascular ' bundle of simple structure, containing
spiral and annular tracheides. The leaves of Azolla are very crowded,
and are placed in two rows on the dorsal side of the stem ; but in some
species they have the appearance of standing in four rows. They are of
delicate membranous texture, and are always deeply bifid, one lobe being
submerged and the other floating. The floating lobe of each' leaf has a
remarkable cavity, covered by a double epidermal layer, with the excep-
tion of a narrow orifice which opens into the cavity. This cavity is
formed during the growth of the leaf by a more rapid growth of the
epiderm than of the subjacent tissue, and is itself clothed with an epi-
dermal layer. The cavities are frequently occupied by well-developed
colonies of Nostoc-filaments. Salvinia is remarkably heterophyllous
(see figs. 7, 8). The first leaf of the young plant is the scutiform or
peltate leaf already mentioned, which is produced near the base of the
stem. It is coriaceous in texture and sagittate in form. Next are pro-
duced, also singly, two ovate aerial leaves. All the subsequent leaves
are arranged in whorls of three, two of which are aerial, with flat, ovate,
or orbicular lamina, floating on the surface of the water ; while the third
or submerged leaf at once branches into long slender filiform segments,
which hang down into the water and perform the function of roots. The
leaves of adjacent whorls are placed alternately, so that the mature plant
has two rows of ventral submerged, and four rows of dorsal aerial
leaves. Each leaf has a single definite apical cell in Salvinia, but not in
Azolla. The leaves of both genera are furnished with stomates, which,
according to Strasburger, differ considerably, both in structure and

RHIZOCARPE&

appearance, from those of Flowering Plants. Those of Salvinia are re-
markably small, and are inserted about halfway up the epidermal cells,
which are eight or nine times their height. Air-pores occur also in the
submerged leaves. The very simple roots of Azolla are of endogenous
origin. The root-cap originates from a single cell ; in A. Caroliniana
(Willd.) the cap is eventually thrown off, leaving the root-tip naked.

The sporanges are enclosed in unilocular sporocarps, formed two
together or in larger numbers ; in Salvinia on the youngest teeth of the
submerged leaves, in Azolla on the pendent submerged lobe of the
deeply bifid leaves, and only on the lowermost leaf of each shoot. The
leaf-segment which is destined to become fertile first of all develops
into a columel or placenta, to which the sporanges are attached. An
annular wall, the rudiment of the in-
dusium, then becomes elevated from
the base of the columel, eventually
overtops its apex, closes up, and
thus forms the wall of the sporocarp.
The sporocarp of Salviniaceae is
therefore a metamorphosed portion
of a leaf, and corresponds to a sorus
in the Hymenophyllaceae (Filices),
with the difference that in the latter
the envelope remains open in the
form of a cup, while in the former it
closes completely over the sorus,
as in Cyathea (Filices). The in-
dusium is much more strongly
developed than that of ferns, and
completely envelops the sorus ; it
consists of two layers of cells, the
walls of which are, in Azolla, strongly lignified in the upper part. Each
sporocarp contains one kind of sporange only \ but both kinds always
occur on the same individual, and may even spring from the same
metamorphosed leaf. In Salvinia the megasporanges are considerably
larger than the microsporanges, and the number of the latter in a sporo-
carp is greater (see fig. 7). In Azolla the number of microsporanges in
a sporocarp is about forty, while the female sporocarps contain only a
single megasporange, and consequently only a single megaspore, en-
veloped first in the wall of the sporange, and then in the greatly hardened
indusium. The microsporanges are nearly globular capsules, with long
slender pedicels, the wall consisting, when mature, of a single layer of
cells. The megasporanges are pear-shaped, with much shorter and

FIG. 12. — Fertile shoot of Azolla filiculoides
Lam., with two female sporocarps, a, ( x 27).
(After Strasburger.)

3o VASCULAR CRYPTOGAMS

stouter pedicels, and arise from the apex of the columel. In the forma-
tion of the pedicels of the megasporanges longitudinal cell-division takes
place, as well as transverse. The mode of formation of the spores
within each kind of sporange has already been described in general
terms, after the preliminary separation of a single external layer of cells
which develops into the wall of the sporange. The sixty-four micro-
spores appear to be disposed without any arrangement in the cavity of
the microsporange. A large nucleus lies at the end of the megaspore
which is nearest the apex of the sporange. Before fertilisation both
kinds of sporange become detached from their pedicels, and are carried

FIG. 13. — Massula of Azolla Caroliniana Willd. (X24o). (After Strasburger.)

up to the surface of the water in the spring by the surrounding masses
of Algae. The epi spore then splits above the apex of the megaspore
into three lobes, between which the emerald-green prothallium forces
itself, and impregnation is effected. In Azolla the epispore assumes a
still more striking form. In the microsporanges it has the appearance
of a large-celled tissue, and breaks up into two or more spherical masses
called massulce, each of which envelops a number of microspores, and
has a distinct coat. In some species, but not in all, the surface of these
masses is covered with hair-like appendages, barbed at the apex, the
glochids, by means of which, after emerging from the sporange, and
when floating on the surface of the water, they attach themselves to the

RHIZOCARPEAZ 31

floating megaspores. The roundish megaspore, which does not nearly
fill up the sporange, is completely covered by a very thick warty layer
of hardened frothy mucilage, its epispore, which projects far above the
apex, and separates, in its upper part, into either three or nine large
pear-shaped masses of the same substance, terminating in a tuft of fine
threads. These bodies constitute a floating apparatus for the megaspore,
the fine threads floating on the surface of the water, and suspending
beneath them the float-corpuscles, either three in number or more
numerous, containing abundance of air-cavities, and the megaspores, to
which the microspores are attached by their glochidiate processes.

The two genera of Salviniaceae, Salvinia and Azolla, each include
but a small number of species, all annual plants, widely distributed over
the globe, especially in its warmer regions. Those of Azolla form green
or red floating patches of considerable size, with the habit of a Junger-
mannia. No economical application is known of either genus.

ORDER 2. — MARSILEACE^E.

The female prothallium attains here a much smaller degree of
development than in the Salviniaceae. It arises within the apical papilla
of the megaspore, the protoplasm of which breaks up into several cells,
which remain for a time unclothed with cellulose, and only subsequently
constitute a tissue containing a small quantity of chlorophyll. Even
after this the prothallium still remains for some time completely enclosed
within the apical papilla of the megaspore, being covered by the epi-
dermal layers of the apex of the spore itself, and shut off from the
spore-cavity within and below by a diaphragm which is attached to the
internal coat Of the spore. By the further growth of the prothallium
the epidermal layers of the apical papilla are broken through, and the
dorsal ridge of the prothallium projects into the funnel formed by the
absence at this spot of the thick outer layers of the epispore. The
diaphragm subsequently arches convexly, and the prothallium is pushed
further outwards, but still lies as a hemispherical mass in the funnel-
shaped opening.

In those species which have hitherto been examined each prothallium
produces only a single archegone. Even before the prothallium breaks
through the megaspore, the large central cell may be recognised in it,
covered only by four cells arranged in a cross, which form at the same
time the apex of the prothallium. From these are developed the more
or less projecting neck and the stigmatic cells of the archegone. As in
Salviniaceae, a neck-canal-cell is separated from the central cell, which
pushes up between the neck-cells, as well as a smaller ventral canal-cell ;

VASCULAR CRYPTOGAMS

the lower and larger portion of the protoplasmic cell-contents contract-
ing into an oosphere. If the archegone remains unfertilised the prothal-
lium continues to grow into a comparatively large chlorophyllous structure
with rhizoids.

The male prothallium and antherids are reduced to a still more

FIG. 14. — Marsilea salvatrix L. Longi-
tudinal section through megaspore, pro-
thallium, and embryo. ant, starch
grains ; i, inner coat ; ex, epispore ; c,
space beneath diaphragm ; pt, prothal-
lium ; wh, its rhizoids ; a, archegone ;
f\ foot ; TV, root of embryo ; b, coty-
ledon ; si, mucilaginous envelope of
megaspore. (After Goebel, X 60.)

FIG. 15. — Marsilea salvatrix. A, prothallium
pt, projecting from ruptured coat r of mega-
spore ; si, layers of mucilage forming funnel,
with antherozoids. B, vertical section of
prothallium pt ; o, oosphere ; a, stigmatic
cells. (After Goebel, greatly magnified.)

rudimentary condition than in the Salviniaceae. The contents of the
microspore divide into three cells, one of which (the prothallium)
remains sterile, the other two constituting the antherid. The contents
of each of these two cells again divide into sixteen antherozoid-mother-
cells. From the nucleus of each of these is formed an antherozoid ;

RHIZOCARPE^E

33

these bodies are therefore developed entirely within the microspore,
while the microspores themselves are set free completely from the
sporange. As in the Salviniaceae, the whole of the contents of the
mother-cell is not used up in the formation of the antherozoid ; a por-
tion remains behind in the form of a roundish turbid lump consisting of
protoplasm and starch -grains, which gradually becomes clearer, and
attaches itself, in the form of a vesicle, to the antherozoid, which in
Pilularia becomes soon detached, but in Marsilea remains attached to
the antherozoid during the greater portion of the period of ' swarming.'
When the antherozoids are mature the exospore of the microspore
bursts at its apex, and the endospore swells up into a hyaline bladder,

FIG. 16. — Pilularia globulifera L. Longitudinal
section of megaspore. a, coat of spore ; b, c,
d, the three layers of the epispore. (After Luers-
sen, magnified.)

FIG. 17. — Marsilea salvatrix. Micro-
spore discharging antherozoids. ex,
exospore ; dl, endospore ; zz, anthe-
rozoids ;yy, their vesicles with starch-
grains. (After Goebel, X3so.)

which finally bursts to allow of the escape of the antherozoids with their
vesicles. In Pilularia the antherozoid consists of only four or five coils
with a few vibratile cilia ; in Marsilea it is of considerable length, the
shape of a corkscrew, and consists of twelve or thirteen coils, the vibra-
tile cilia being also of great length. The antherozoids collect, in large
numbers, in the funnel-shaped depression of the epispore of the mega-
spore above the prothallium (see fig. 15), and force themselves, through
the neck of the archegone, to its central cell.

In its early stages the development of the oosperm or impregnated
oosphere corresponds to that of Salviniacese. After becoming invested
with a cell-wall of cellulose, the first segmentations give rise to the

D

34 VASCULAR CRYPTOGAMS

parent-cells of the first root, of the young stem, of the first leaf or
cotyledon, and of the foot by which the young embryo is attached to
the prothallium. In Marsilea a second cotyledon is formed from the
fourth octant of the lower half of the embryo. The layer of tissue
surrounding the central cell becomes double after impregnation ; a few
grains of chlorophyll are formed in it, and its outer cells develop into
long rhizoids, which are especially luxuriant if no fertilisation has taken
place.

The sporophyte of the Marsileaceae differs very widely in external
form in the two genera ; but its internal structure agrees in its essential
features with that of the Salviniaceae. The stem, root, and leaves all
originate from a single apical cell, which always divides into three rows.
The stem is procumbent on damp soil or at the bottom of stagnant
water, and is traversed by a single central * vascular ' cylinder filled with
fundamental tissue, each bundle consisting of a central xylem with spiral
or scalariform tracheides, surrounded by a phloem with large sieve-tubes
and sieve-plates, and the whole enclosed in a brown sclerenchymatous
bundle-sheath, composed of a single layer of cells with wavy lateral
walls. A single ' vascular ' bundle traverses each root and leaf-stalk ;
in the lamina of the leaf of Marsilea this branches into a dichotomous
venation. The fundamental tissue abounds, in both genera, in large
schizogenous intercellular cavities, as is usually the case with water-
plants. Those of Marsilea form a complete intercommunicating system.
In those of Pilularia are remarkable spiral hairs. The leaves develop
basifugally, as in Salviniaceae ; they are formed in two alternating rows
on the dorsal side of the stem ; but, as in Salviniaceae, it is not every
segment of the stem that produces a leaf. In this respect the Rhizo-
carpeae agree with Filices, and differ from Equisetacese and Muscineae.
The leaves are circinate in vernation, resembling in this respect true
ferns only. Tannin-sacs occur in the petiole. In Marsilea (see fig. 6)
all the leaves except the first, which is filiform and destitute of a lamina,
have a very long slender petiole and a four-lobed lamina ; they are
larger when growing in water than on dry land. M. quadrifolia (L.) has
stomates on both surfaces of the aerial, on the upper surface only of the
floating leaves. The stomates are depressed in the tissue of the leaf by
the growth of the adjoining epidermal cells over the guard-cells. The
mesophyll of the aerial leaves is characterised by the presence of rows of
sclerenchymatous cells. In Pilularia the petiole is elongated and quill-
like, and entirely destitute of a lamina (fig. 5).

The sporocarp or conceptacle of the Marsileaceae is an even more
complicated structure than that of the Salviniaceae. In Pilularia it is a
roundish, shortly-stalked capsule springing from the axil of a leaf-stalk

RHIZOCARPEsE

35

on the procumbent stem. According to Juranyi, each sporocarp is the
result of the coalescence of two segments of bifid leaves. The wall of
the sporocarp is very thick and hard, and consists of several layers of
cells forming a sclerenchymatous tissue. It is divided by vertical walls
into compartments, varying from two to four in the different species.
Each compartment has, at least in its young state, an opening at the
apex, and is therefore not of endogenous origin, but rather a depression
in the surface. In each compartment there is, on the side which forms
its outside wall, a cushion-like placenta, formed from superficial cells,
and resting on a ' vascular ' bundle. To this placenta are attached a
number of stalked sporanges of both kinds, constituting a sorus ; the
megasporanges are chiefly below,
and the microsporanges above.
The remainder of each compart-
ment is occupied by a delicate
thin-walled parenchyme. When
mature the sporocarp splits from
the apex downwards into as many
valves as it has compartments ;
and each sporange dehisces by
the expansion of the gelatinous
mass resulting from the dissolu-
tion of the tapetal cells.

The sporocarps of Marsilea
are capsules with somewhat the
shape of a bean, a longer or
shorter pedicel,^ and a very hard
sclerenchymatous wall. They
spring, usually in clusters, from
the petiole of an ordinary leaf.
The pedicel runs along the dorsal edge of the sporocarp, and gives
off lateral veins right and left which branch dichotomously and run to
the ventral edge. The ripe sporocarp has a bilaterally symmetrical
structure, and is divided by transverse walls into two rows of compart-
ments, each of which has, when young, a narrow opening on the ventral
side. Each compartment contains a single sorus, consisting of a few
megasporanges in the centre, with a larger number of microsporanges on
each side. As in Pilularia, a large portion of the cavity of each compart-
ment is occupied by a succulent parenchyme.

The development of the sporanges commences, in both genera, with
the swelling up of some of the epidermal cells of the part which
ultimately becomes the placenta. These cells divide several times

FIG. 18. — Transverse section of sporocarp of Pilu-
laria. globulifera. mi, microsporanges; ma,
megasporanges ; e, wall of sporocarp ; g, paren-
chyme. (After Goebel, magnified.)

36 VASCULAR CRYPTOGAMS

obliquely — not horizontally, as in Salviniaceae — into three rows of seg-
ments, until ultimately a convex septum cuts off a triangular apical cell,
which at length becomes the tetrahedral archespore. From this is
separated the mantle-layer of tapetal cells ; further divisions take place
both in these and in the rows of cells of which the wall of the sporange
is composed, and the archespore divides by successive bipartitions into
sixteen spore-mother-cells, each of which produces four spores in the
ordinary way. The pedicel of the sporange consists at first of three rows
of cells, the number being subsequently increased by further longitudinal
divisions. The tapetal cells become gradually disorganised, and form a
granular mucilage, filling up the interstices between the mother-cells of
the spores, which is subsequently employed in the production of the
epispore or gelatinous envelope of the spore. The differentiation of the
two kinds of spore now commences. In the microsporanges all the
sixty-four microspores reach maturity, each special mother-cell or rudi-
mentary spore becoming invested, while still within the mother-cell, with
its permanent cell-wall, while the walls of the sixteen mother-cells dis-
appear. In the megasporanges, on the other hand, one of the four
special mother-cells in each of the sixteen tetrads displays at first a
greater vigour of growth than the other three. Of these sixteen sister-
cells fifteen gradually become abortive, only one reaching maturity and
developing into a perfect megaspore. During their development and
disappearance all the rudimentary spores are furnished with -spiny pro-
tuberances, by which they are attached to one another. As the mega-
spore increases in size its coat becomes hard and brown ; and it is ulti-
mately invested by a gelatinous epispore consisting of three distinct
layers (fig. 16). The innermost of these is a mucilaginous coat, which
is often folded, and ultimately forms a papilla above the apex of the
mature spore. Outside this is a thicker layer of a soft prismatic sub-
stance, and external again to this a third still thicker but less clearly
organised envelope. The two outer layers are wanting at the apex of
the spore, where there is a funnel-shaped depression exposing the papilla
belonging to the innermost layer of the epispore. Down \\\\s funnel the
antherozoids pass to impregnate the oosphere within the archegone pro-
duced on the prothallium within the apical papilla of the megaspore.

The processes by which both kinds of spore escape from the very
hard shell- of the sporocarp are very remarkable. In Pilularia globu-
lifera (L.) the ripe sporocarp lies above or beneath the surface of the
damp soil. It splits from its apex downwards into four valves, and
exudes a tough hyaline mucilage derived from the parenchymatous
tissue within each compartment. This mucilage accumulates on the
ground ; and into it both kinds of spore escape after the rupture of the

RHIZOCARPE^:

37

sporanges. Fertilisation takes place within the drop of mucilage, which
then gradually disappears, and the impregnated megaspore lies on the
damp ground, to which it becomes attached by the rhizoids put out
from the prothallium until the first root of the embryo penetrates into
the soil. In Marsilea the processes are somewhat similar. The exces-
sively hard, almost stony, shell of
the sporocarp gives way slightly at
its ventral edge as it lies in water,
and the water penetrates into the
interior. This causes the suc-
culent parenchymatous tissue in
each compartment to swell up,
and splits the shell along the whole
of the ventral edge into two valves.
Between these valves the contents
are gradually forced out; the com-
partments still remain closed, each
enclosing a sorus, and are attached
in two rows to the cartilaginous
cushion or sorophore which ran
along the ventral edge of the spo-
rocarp, and which now becomes
detached at one end, and ex-
posed in the form of a string
many times longer than the sporo-
carp itself ; by the absorption of
water it has increased enormously
in size, to something like 200
times its original dimensions, and
the sori are thus placed at a con-
siderable distance from one an-
other. Ultimately the walls of
the sori or original compartments
of the sporocarp disappear ; the
walls of the sporanges burst, both
kinds of spore escape, and fertilisation is effected on the damp soil.

All the species of both genera of Marsileaceae are marsh or aquatic
perennial plants, mostly natives of the warmer temperate and tropical
countries. The number of species of Pilularia is small, of Marsilea
about forty. The leaves of Marsilea, when growing in the air, display a
sensitiveness to light, folding up in the evening and expanding in the
morning, similar to those of many Leguminosse and other Flowering

FIG. 19. — Sporocarp of Marsilea salvatrix. A,
transverse section. B, swollen and bursting,
showing sorophore ( x 2$). C, sporocarp (natural
size), with sorophore fully extended, and sori
attached. D, section of sorus ( x 6) ; ids, indu-
sium ; mik, microsporanges ; mak, megaspo-
ranges. (After Hanstein.)

38 VASCULAR CRYPTOGAMS

Plants. The sporocarps of M. Drummondii (Br.), and probably of some
other species, are eaten by the natives of Australia under the name of
nardoo.

LITERATURE.

Bischoff — Die Rhizocarpeen und Lycopodiaceen, Nuremberg, 1828.

Mettenius— Beitr. zur Kenntniss der Rhizocarpeen, 1846; Linmea, 1847, p. 260;

and Beitr. zur Botanik, Heft i, 1853; Plantse Tinneanse.
Meyen — Nov. Art. Acad. Caesar-Leopold., vol. xviii., pt. I, p. 253.
Hofmeister — Ueb. Keimung der Salvinia, Abhandl. Sachs. Gesell. Wiss. 1857,

p. 665.

Pringsheim — (Salvinia) Jahrb. f. wiss. Bot., vol. iii., 1863, p. 484.
Hanstein — Ueb. eine neuhollandische Marsilia, Monber. Berl. Akad., 1862, p. 183 ;

Befruchtung u. Entwickelung der Marsilia, Jahrb. f. wiss. Bot., vol. iv., 1865,

p. 107 ; Pilularise generatio cum Marsilia comparata, Bonn, 1866.
Braun — (Marsilia and Pilularia) Monber. Akad. Wiss. Berlin, 1870, p. 653, and

1872, p. 668.
Russow — Vergleich. Unters., Petersburg, 1872 ; and Hist. u. Entwick. d. Sporen-

frucht v. Marsilia, Dorpat, 1877.
Strasburger — Ueber Azolla, Jena, 1873.
Juranyi — Ueb. d. Entwick. d. Sporangien u. Sporen v. Salvinia, Berlin, 1873 ; and

(Pilularia) Sitzber. Ungar. Akad. Wiss., 1879(566 Bot. Centralbl., vol. i., 1881,

p. 207).

Berggren— (Azolla) Rev. Sc. Nat., 1881, p. 21.

Heinricher — (Spores of Salvinia) Sitzber. Akad. Wiss. Wien, vol. Ixxxv., 1882, p. 494.
Goebel— (Pilularia) Bot. Zeit., 1882, p. 771.

Class II.— Selaginellaceae.

This class is composed of two genera only, Selaginella (Spring) and
Isoetes (L.), resembling one another in the general facts of their life-
history, but differing widely in external appearance, and each consti-
tuting a monotypic order. We have, again, as in Rhizocarpeae, two
kinds of spore; the megasporanges and microsporanges are of very
similar appearance, and are produced in connection with the leaves.
The female prothallium, produced within the megaspore, is a more
completely endogenous structure than in any other class of Cryptogams,
and is altogether destitute of chlorophyll. From the occurrence in both
genera of a foliar structure known as the ligulet the term ' Ligulata? '
is sometimes given to the class ; but the character is unsatisfactory,
and it will be best to treat the two orders Selaginellece and Isoetece sepa-
rately.

SELA G I NELL A CE^E

39

ORDER i. — SELAGINELLE^E.

In the genus Selaginella, the sole representative of the order, the
prothallium appears to be already completely formed by the time the
megaspore is mature, but occupies only the apical portion of the cavity
of the spore ; the basal
portion is still filled by an
undifTerentiated mucilagi-
nous protoplasm, which
subsequently develops into
a cellular tissue, the second-
ary prothallium, or, as it
is termed by some writers,
the endosperm. In some
species, at least, this struc-
ture is separated by a dia-
phragm from the true pro-
thallium. The prothallium
always produces a number
of archegones, sometimes
as many as thirty, which
arise in centrifugal succes-
sion on the exposed portion
of the prothallium, the one
formed first being at the
apex. The archegone ori-
ginates by division of a
superficial cell in a direction
parallel to the surface ; the
outer of these two then
divides into four cells, and
each of these again breaks
up by tangential division
into two. These form the
neck of the archegone, which
therefore consists of four
rows, each composed of
two cells. The lower of
the two original cells becomes the venter of the archegone, and puts out
a slender prolongation between the neck-cells, which is separated as the
neck-canal-cell . Another very small portion is subsequently separated

H

FIG. 20. — A — F, stages in the division of the microspore of
Selaginella, caulescens Spr, z>, sterile cell ; G, antherozoid
(x 1400); ff, vertical section of megaspore of S. Mar-
tensii Spr. ; p, prothallium with three archegones ; end, en-
dosperm ; e, exospore(x 165). (After Pfeffer.)

40 VASCULAR CRYPTOGAMS

as the ventral canal-cell, and the protoplasm of the larger and lower
portion rounds itself off into the oosphere. The two canal-cells then
deliquesce into mucilage, leaving an open passage for the entrance of
the antherozoids.

The microspores, spherical orange or bright red bodies, remain in
a dormant condition through the winter, and undergo further develop-
ment in the spring. The contents then divide, first of all by a trans-
verse wall of cellulose near one end into two cells of very unequal size.
The smaller one of these does not divide further, and remains sterile ;
it is regarded as the last degraded vestige of a male prothallium. The
contents of the larger of the two cells, which may be regarded as an
antherid, then break up into from four to eight primordial cells, and
each of these divides again into four mother-cells of antherozoids ; but
it is uncertain whether all the cells are fertile. The antherozoids are
coiled up into a helix, and are furnished at the anterior end with two
long fine cilia. The antherozoid is in all cases derived from the nucleus
of the mother-cell ; a central vacuole, invested with a delicate membrane,
often remains attached to its posterior end during ' swarming.' The
' swarming ' condition continues for about half to three-quarters of an
hour.

FIG. 2i. — Formation of embryo and suspensor in 5". Martensii, showing order of formation
of dividing walls. (After Pfeffer.)

In the formation of the embryo the first division of the oosperm
differs from that in Rhizocarpeae and in Filices in taking place at right
angles to the axis of the archegone. It is thus divided into two super-
posed halves, from the lower of which is developed the embryo itself ;
from the upper half a structure almost peculiar to this order, consisting

SELAGINELLACEsE 41

of a small number of large cells, known as the suspensor, or pro-embryo,
from its apparent homology with the structure which goes by this name
in Flowering Plants. By the elongation of the suspensor and the
compression and absorption of the adjacent cells, the lower portion of
the oosperm is forced into the endosperm, from which it appears to
derive nutriment, dividing, both previously and subsequently, into a
small-celled tissue. This tissue undergoes a large amount of differentia-
tion before the embryo emerges from the megaspore, the rudiments of
all the principal parts of the sporophyte making their appearance at this
early stage. The mother-cell of the embryo divides into two by an
oblique wall. From one of the two cells thus formed originate the stem
and one of the cotyledons, from the other the foot and the other coty-
ledon. The rudimentary stem has a two-edged apical cell, from which
segments are cut off alternately right and left. An inner mass of tissue
soon becomes differentiated as the procambium of the axial ' vascular '
bundle, the peripheral tissue as dermatogen and periblem. The stem-
bud, or plumule, with its first leaves (subsequent to the cotyledons),
finally grows erect from the apex of the megaspore as the embryo
increases in length. The formation of the first root begins later between
the foot and the suspensor ; its apical cell is formed from an inner cell
of the older segment \ the first layer of its root-cap originates from the
splitting into two layers of the overlying dermatogen ; the later layers of
the root-cap are formed from the apical cell of the root.

The sporophyte differs greatly in appearance in the two orders.
In Selaginella the stem is always slender, erect or procumbent, with
distinct internodes, and lengthening rapidly by monopodial branching,
which very often has a dichotomous appearance from the vigorous
growth of the lateral branches. These lateral branches, with their
ramifications, frequently develop in a single plane, giving the system
the appearance of a compoundly pinnate leaf; all the branches and
leaves displaying a distinctly dorsiventral character. The stem has an
epiderm composed of elongated prosenchymatous cells, without
stomates, but containing a considerable amount of chlorophyll in re-
markably large grains. The fundamental tissue consists of elongated
thin-walled 'cells with oblique septa, fitting closely together without
intercellular spaces, and • endowed with the power of long-continued
growth both in length and diameter. In the absence of small inter-
cellular spaces the stem of Selaginella resembles that of mosses ; but,
on the other hand, each ' vascular ' bundle is surrounded by a large
air-cavity, traversed by trabecules, rows of cells connecting the bundle
with the surrounding fundamental tissue. The entire cortex has a
tendency to become dark brown with age from partial sclerosis. When

42

VASCULAR CRYPTOGAMS

the cells of which these trabecules are composed are round, they form a
loose spongy parenchyme surrounding the bundle, and sharply differ-
entiated from the firm compact fundamental tissue. The stem has
one or more cauline { vascular ' bundles, which may be traced in the

FIG. *-2.—Selazinella inaqnalifolia Spr. A, branch (natural size); B, microsporange ; C, megasporange

(greatly magnified).

procambial condition to the apex of the stem close beneath the apical
cell and above the youngest leaves : the separate bundles which descend
from the leaves (leaf-trace-bundles) only unite with the cauline ones at a
later period. The bundles are usually ribbon-shaped, and are concen-

SELA GIN ELL A CE^

43

trie and closed. In the centre is the xylem, consisting chiefly of scalari-
form and reticulate tracheides ; this is completely surrounded by the

FIG. 23. — Transverse section through leaf of 6". in&qualifolia. ch, chlorophyll-bodies ; co,
upper epiderm ; eu, lower epiderm ; sp, stomates ; /, air-cavity surrounding vascular bundle
and traversed by trabecules. (After Goebel, magnified.)

FIG. 24. — Transverse section of stem of 6". denticulata Lk. b, air-cavity
surrounding ' vascular ' bundle. (After Goebel, magnified.)

thin- walled phloem. The primary elements of the xylem, very narrow
spiral tracheides, are formed at the angles of the bundle, and from them

44

VASCULAR CRYPTOGAMS

the development and lignincation of the tracheides advance centripe-
tally. The external layer of phloem is itself surrounded by two or
three parenchymatous layers, constituting a bundle-sheath^ belonging
to the fundamental tissue, but within the large air-cavity. The mode
of apical growth varies in the different species. In some the apex of
the stem is occupied, as in Isoetes, by a group of equivalent meris-
matic cells ; while in others there are two co-ordinate apical cells side

by side, or a single one,
which may be two-sided or
three-sided.

The leaves are simple
and unbranched, and are
traversed by a single ' vas-
cular' bundle. They are
always of small size, re-
sembling those of Lycopo-
dium, awl-shaped and acu-
minate, or ending in a
delicate awn, and usually
with a cordate base. The
greater number of species
are heterophyllous, the
sterile leaves having two
different forms ; those on
the ventral or shaded side
of the obliquely ascending
stem are larger than those
on the dorsal side exposed
to the light. They are
always in four rows, one
dorsal and one ventral leaf
forming a pair. On the
upper side of the leaf near
its base is the peculiar

structure known as the ligule^ from the presence of which the class has
sometimes been called * Ligulatse.' The fertile leaves are uniform in size,
and differ somewhat in shape from the sterile, forming a compact square
terminal spike. The sporange springs from the upper surface below the
ligule. In some species the epiderm is alike on the two sides of the leaf ;
in others it differs. The epidermal cells contain chlorophyll, as is the case
in ferns, and frequently have beautifully serpentine lateral walls ; in some
species they are so greatly thickened that the cell-cavity disappears alto-

FIG. 25.— S. inaqualifolia ; transverse section of stem
( x 150). (After Sachs.)

SELAGINELLACE& 45

gether. The chlorophyll, both in the epidermal cells and in the meso-
phyll, is collected into large lumps, in which are grains of starch.
Stomates occur in the under, rarely also in the upper surface. The
mesophyll consists of a loose spongy parenchyma ; when the leaves are
very small it is developed only as a single layer surrounding the central
' vascular ' bundle, and is altogether suppressed near the margins, where
the upper and lower epiderm are in actual contact.

True roots occur in all known species belonging to the order. In
some species of Selaginella a structure known as the rhizophore inter-
venes between the stem and the root. The rhizophores resemble roots
in general appearance, but are destitute of a root-cap. They may spring
either from the dorsal side of the stem only, near the base of a branch,
bend round and then grow downwards, or two may spring from each
fork, one on the dorsal, the other on the ventral side, the former of which
usually remains undeveloped in the form of a small protuberance, while
the latter grows to the normal size. Their origin is very near the grow-
ing point, and they appear to be formed in the same way as the branches.
Unlike the roots, they are exogenous structures. After apical growth
has ceased, the end of the rhizophore, which is still very short, swells up
into a spherical form ; its cell- walls become thicker, and the first rudi-
ments of the true root originate in the interior of the swelling, but do
not break through the surface until the rhizophoLe has increased consi-
derably in length by intercalary growth, and its swollen end has penetrated
the soil, where its apical cells deliquesce into mucilage, through which
the true roots reach the ground. In some species the rhizophores are
frequently transformed into leafy shoots, which at first manifest some
deviations from the normal structure of aerial shoots, but afterwards
present the ordinary structure, and may even bear sporanges. The
rhizophore is not, however, universal in Selaginella. In many species
the roots spring directly from the lowest fork of the stem, and branch
monopodially before they reach the ground. They originate, like those
borne by the rhizophores, near the growing point. All the roots branch
copiously, the planes of the successive branchings crossing one another
at right angles. They have a single apical cell, but this soon ceases to
give off segments, and the subsequent increase in length is chiefly due
to intercalary growth.

Both kinds of sporange are shortly stalked nearly spherical capsules
(fig. 22), closely resembling those of Lycopodium in appearance and
structure, except in their being heterosporous. They are collected into
dense spikes at the extremity of somewhat metamorphosed leafy shoots.
The lower portion of each spike in some species consists of megaspo-
ranges, the upper portion of microsporanges, and the former may be

VASCULAR CRYPTOGAMS

reduced to only one. Each fertile leaf or sporophyll subtends only a.
single sporange, which is borne on the stem above the leaf-axil. The
sporanges are of considerable size in proportion to that of the leaf, and
are formed from a group of superficial cells at the growing point of the
stem. They make their first appearance as flat, afterwards spherical or

club-shaped, swellings, completely
covered by the epiderm, which
subsequently forms, by tangential
divisions, the wall of the sporange,
composed of three layers. By
subsequent growth the sporange

FIG. 27.— Section of megasporange of 6".
intpquctlifolia, showing double wall of
sporange, layer of tapetal cells, and mega-
spores. (After Goebel, magnified.)

comes to be placed in the axil or
even on the base of the leaf. The
' vascular ' bundle of the leaf passes
beneath the sporange without
sending a branch into it. As in
the other heterosporous families,

the two kinds of sporange present no differentiation in their early
stages. The archespore is the terminal hypodermal cell of an axial row.
This divides into the sporogenous tissue surrounded by the layer of tapetal
cells formed from the innermost of the layers of cells into which the wall
of the sporange divides. In the megasporanges one of the spore-mother-
cells grows more vigorously than the rest, which gradually abort. In this

FIG. 26. — A, fertile branch of S. inteqnali-
folia (half natural size). B, longitudinal
section of upper part, showing microspo-
ranges and megasporanges. (After Goebel ,
magnified.)

SELAGINELLACE^ 47

•

privileged cell are formed four spores, the number usually present in
the mature megasporange. The microspores are formed in the same
way as in the other heterosporous families. After falling out of the
sporange they frequently adhere together in fours. The microspore
has three coats — endospore, exospore, and epispore — of which the inner-
most is composed of cellulose. The coat of the megaspore is also
treble, and the epispore is not unfrequently beautifully granulated and
spiny. The dehiscence of both kinds of sporange is caused by the
unequal contraction of the epidermal cells. The microsporanges are
2-valved, the megasporanges 3-4-valved.

The genus Selaginella (Spring) includes above 300 species, spread
over the whole globe, but most abundant in the tropics. Many species
resemble Lycopodium very closely in habit, but are more moss-like,
and the leaves generally more delicate ; in others the stem is erect, and
they reach the magnitude of small shrubs. Several species are favourite
objects of cultivation from the beautiful metallic lustre of the leaves.
They are readily propagated non-sexually, a small fragment of the stem
producing a new plant if kept warm and moist on loose earth, owing to
the production of adventitious roots in the angle formed by the branch-
ing of the * vascular ' bundle of the leaf from that of the stem. No
economical use is known of any species either of Selaginella or
Isoetes.

ORDER 2.— ISOETE^E.

In the single genus Isoetes the general phenomena of the life-history
correspond to those of Selaginella, but with some important differences.
Some weeks after the escape of the megaspore from the decaying mega-
sporange its cavity becomes filled, by free-cell-formation, with a number
of naked primordial cells, which gradually fill up the whole cavity of the
endospore, and then become converted into a cellular tissue by the in-
vestment of each with a cell-wall of its own. The endospore at the
same time thickens, and separates into several layers with a finely granu-
lar structure. The epispore, or outer layer of the coat of the megaspore,
now splits at its apex by a three-rayed fissure, exposing the endospore,
which also subsequently disappears, and a portion of the spherical pro-
thallium is thus laid open. At its exposed apex appears the first arche-
gone, which is followed by others if the first is not fertilised. The
archegones resemble those of Selaginella, except that each of the rows
which constitute the neck is composed of four instead of two cells.

The microspores are yellowish grey, and of the form of the quadrant
of a sphere. The antherozoids are very long, slender, and attenuated

48 VASCULAR CRYPTOGAMS

at both ends, where they are provided with two tufts of very long cilia ;
in some species they are remarkably large. Their period of ' swarming '
does not last more than about five minutes.

The stem of Isoetes is distinguished by its extraordinarily restricted

FIG. 28. — Isoetes lacustris L. (natural size).

growth in length, and the complete absence of branching, as well as by
a remarkable secondary increase in thickness. It is completely covered
by the bases of the leaves, leaving no part exposed. Its upper portion
has the form of a shallow funnel, with the apex depressed in its centre.

SELA GIN ELL A CE^

49

The long-continued increase in thickness which distinguishes this genus
alone among Vascular Cryptogams — except possibly Botrychium (Filices)
—is dependent on an internal layer of meristem which surrounds the
axial 'vascular' cylinder, and continually produces new layers of paren-

FIG. 29. — A, megaspore of Isoctes acustris L. £, prothallium ; a, archegone (x about 50).
(After Hofmeister.)

chyme on the outside. This takes place especially in either two or
three directions, so that a corresponding number of projecting masses of
tissue are formed, which slowly die off on the outside ; and between
them lie the same number of furrows meeting on the ventral side of the
stem, which has hence the appearance of a laterally elongated plate or

FIG. 30. — /. lacustris. A — D, microsppre, showing stages in formation of antherid and antherozoids
(x 580). ?', sterile cell ; a— d, stages in formation of antherozoid (x 580) ; e,f. mature antherozoid
( x 700). (After Millardet.)

disc. In these furrows are produced a large number of rows of roots in
acropetal succession. In the stem is a single cauline axial bundle com-
posed of short reticulate and spiral tracheides, surrounded by a rudi-
mentary phloem without sieve-tubes. From this axial bundle there

VASCULAR CRYPTOGAMS

proceeds a branch into each leaf and one into the root. The layer of
meristem which surrounds the axial bundle increases chiefly in the
centrifugal direction, fresh layers thus formed replacing the outer ones,
which continually die off. The secondary long-enduring increase in
thickness of the stem is chiefly due to increase in thickness of the cortical
tissue, though new xylem-elements are also produced. The mode of
apical growth differs from that in most species of Selaginella. There is
no single apical cell, the apex of the stem being occupied by a group of
equivalent merismatic cells.

FIG. 31. — Longitudinal section of stem of 7. lacustris. b—b9,
leaves ; rl — r10, roots : the ligules are shaded ( x 30).
(After Hofmeister.)

FIG. 32.— Longitudinal section
through lower portion of
leaf of /. lacustris (diagram-
matic). L, ligule ; J, indu-
sium ; S#, microsporange ;
TV, trabecules ; Gf, vascu-
lar bundle of sporophyll.
(After Goebel.)

The leaves of Isoetes are very elongated, cylindrical, and quill-shaped,
and are arranged in a complicated phyllotaxis on the very short stem.
They are segmented into a basal portion, the sheath or glossopodt, and
an apical portion, the lamina. The sheath is nearly triangular in form
with a very broad insertion, and does not completely embrace the stem.
It is convex behind and concave in front, where it bears the sporange
in a large depression known as thefovea ; the margin of this depression
rises in the form of a thin membranous outgrowth, the veil or indusium^
which, in many species, extends above and beyond the sporange. Above

SELA GINELLA CE.E 5 1

the fovea, and separated from it by a ridge called the saddle, is a smaller
depression, \hefoveola, the lower margin of which forms a lip-like struc-
ture, the labium, and from its base rises a narrow membranous acuminate
structure, the ligule, with a cordate base, and usually projecting above
the foveola. The sheath passes above into the lamina, which is narrow
and thick, almost cylindrical, but flattened in front, contains chlorophyll,
and is traversed by four wide longitudinal air-cavities, segmented by
transverse septa. A rosette of these fertile leaves or sporophylls is pro-
duced annually, but between these whorls are alternate whorls of phyl-
lades, or imperfec: leaves, consisting, in the submerged species, of only
a small lamina with no sheath, while in the terrestrial species they are
reduced to mere scales. Stomates occur in the paludose and terrestrial,
but not in the submerged species. Scattered spiral tracheides are found
in the parenchymatous base of the leaf. The fundamental tissue, which

A

FIG. 33. — Developmen'. of microsporange of /. lacustris. t, tapetal cells ; TV, trabecules : the
archespore and sporogenous cells derived from it are shaded. (After Goebel, magnified.)

is not separated from the single 'vascular' bundle by a bundle-sheath,
has a strong tendency to become sclerenchymatous, especially beneath
the epiderm and in the sheath. The very simple bundle which occurs
in each leaf is stated by Russow to be collateral, the xylem and phloem
lying side by side.

The roots spring from the furrows of the stem, and resemble, in
structure and mode of branching, those of Selaginella. There is no
rhizophore.

The sporanges of Isoetes do not make their appearance until the
third year after germination. Each sporophyll bears only a single
sporange, which is undoubtedly a product of the leaf, and is situated
below the ligule in the fovea, to which it is attached by a narrow base.
The outer leaves of the fertile rosette produce megasporanges only, the
inner leaves microsporanges only. Both kinds of sporange originate
from a group of cells at the base of the leaf The archespore is derived

E 2

52 VASCULAR CRYPTOGAMS

from a hypodermal layer of cells. In the formation of the microsporange
the archespore-cells elongate in a direction at right angles to the surface,
and divide by transverse walls. Some of these rows of cells are then
arrested in their growth, lose their abundant protoplasm, and divide
into elongated tabular cells constituting the trabecules, which cross the
sporange from the dorsal to the ventral side. The remaining cells
develop into the mother-cells of the microspores, an external layer
having been previously separated as tapetal cells. In the development
of the megasporange the processes are the same as far as regards the
formation of the tapetal cells and the trabecules ; the mature sporange
may contain either four or a much larger number of megaspores. The
mode of development of the megaspores presents perhaps the closest
analogy to that of the secondary embryo-sacs of Gymnosperms that
occurs in any order of Vascular Cryptogams ; and the same remark
applies to the formation of the microsporanges and pollen-sacs. Both
kinds of sporange are indehiscent, the spores escaping only by the decay
of the tissue.

In both kinds of spore the epispore is frequently granulated, tuber-
culate, or echinate ; and in some species there are two kinds of microspore
differing from one another in this respect.

One or two species of Isoetes display the phenomenon of apogamy in
various degrees. In extreme cases the formation of the megasporange
is arrested at a very early stage, and its place supplied by a -vegetative
shoot, which becomes detached and develops into an independent plant.

The number of species of Isoetes is about fifty, the greater part
inhabitants of the warmer portions of the globe. They somewhat
resemble Pilularia in general habit. Some species are aquatic and
entirely or partially submerged, other paludose, and a very few terrestrial ;
and they present corresponding differences in the structure of their tissue,
presence of stomates, &c.

LITERATURE.

Von Mohl— (Stem of Isoetes) Linnsea, 1840, p. 181.

Braun— Ueber Isoetes, Monber. Berlin Akad. Wiss., 1863.

Hofmeister — Entwick. d. Isoetes lacustris, Abhandl. Sachs. Gesell. Wiss., 1865.

Pfeffer— Entwick. d. Reims Selaginella, in Hanstein's Bot. Abhandl., iv., 1871.

Tchistchakoff-( Isoetes) Nuov. Giorn. Bot. Ital., 1873, p. 207.

Bruchmann — Wurzeln v. Lycopodium u. Isoetes, 1874.

Hegelmaier — Bot. Zeit., 1874, p. 481.

Goebel— (Apogamy of Isoetes) Bot. Zeit., 1879, p. I.

Mer— (Sporange of Isoetes) Compt. Rend., xlii., 1881, p. 310; and Bull. Soc. Bot.

France, 1881, pp. 72, 109.

Kienitz-Gerloff— (Embryo of Isoetes) Bot. Zeit., 1881, pp. 761, 785.
Vines — (Isoetes) Annals of Botany, vol. ii., 1888, p. 117.

L YCOPODIA CE^E 5 3

ISOSPOROUS VASCULAR CRYPTOGAMS.

Class III.— Lycopodiaceae.

The Lycopodiaceae are a comparatively small group of plants com-
prised in only four genera, differing from one another greatly in habit,
but agreeing in the prevalence of a dichotomous rather than of a mono-
podial mode of branching in both stem and root, though this is by no
means universal. Growth is effected by a group of equivalent cells in
the growing point, never (except in Psilotum, Sw.) by a single apical
cell. The leaves are always of small size and entirely undivided ; in
Psilotum they are reduced to mere scales, and this genus is also entirely
rootless ; while in Phylloglossum (Kze.) the underground stem is tuberous.
The sporanges and spores are of one kind only ; the spore produces on
germination (where this has been observed) a green or colourless pro-
thallium, which carries on a much more independent existence than is
the case in the heterosporous orders, and bears, in the cases which
have been examined, both archegones and antherids. The position of
the sporanges varies. In the Lycopodieae it corresponds to that of the
Selaginelleae, on the upper side of the base of the leaf, or they are
crowded on special erect branches ; and here the sporanges are unilocu-
lar • while in the Psiloteae they are plurilocular, and are grouped on the
main stem or on short lateral branches. Further details are best described
under the heads of the two orders into which the Lycopodiaceae may
be divided. In the monoecious prothallium the Lycopodiaceae approach
the Ophioglossaceae ; while in the structure of the sporophyte they display
a remarkable resemblance to the heterosporous Selaginellaceae.

ORDER i. — LYCOPODIE.E.

In this order are included two genera of very different habit : Lyco-
podium (L.), with nearly 100 known species ; and Phylloglossum (Kze.),
with only one. The form and appearance of the oophyte vary greatly
even in the different species of the typical genus Lycopodium. The ger-
mination of the spores of L. inundatum (L.) has been described as follows
by de Bary : — The endospore bursts in the form of a nearly spnerical
vesicle through the exospore, which splits into three valves ; the ger-
minating filament which originates in this way then divides by a septum
into a basal cell, which undergoes no further change, and a larger apical
cell, which divides into two rows of segments ; each segment further
divides by a tangential wall into an inner and an outer cell, so that

54

VASCULAR CRYPTOGAMS

the young prothallium now consists of an axial row of four short reHs,
the basal and apical cells, and two lateral rows. The cells contain a
few grains of chlorophyll. The formation of the sexual organs was not
observed. The mature oophyte of L. annotinum (L.) presents several
important differences. The prothallium is underground and of a
yellowish-white colour, destitute of chlorophyll, and consists of a tuberous
mass with cushion-like ridges on the upper side and a few small rhizoids.
On its upper side and completely imbedded in the tissue are a number
of antherids, consisting of cavities covered by one or more layers of cells,
and containing a large number of mother-cells
of antherozoids. The antherozoids themselves
appear to be minute bodies consisting of only
a few coils, and probably with two cilia. The
archegones have not been actually observed,
but are evidently borne on the same prothallium

FIG 34.— Young plant of Lycopo- FiG.35.—A,protha.\\iumofLyc0J0fiiuMcernHitm

dinm annotinum L. /, prothal- L. ; t, tuberous outgrowth ( x 25). £, young plant

Hum; w, root (natural size). of L. cernuum (x2). (After Ireub.)
(After Fankhauser.)

as the antherids, and in close contiguity with them, apparently on the
upper side, in the depressions between the ridges. Only one archegone
appears to be fertilised on each prothallium. The young sporophyte
has no foot, its place being supplied by a tuberous swelling with root-
hairs. A very different type of prothallium is presented, according to
Treub, by L. cernuum (L.). It consists of a short cylindrical axis half
immersed in the soil, containing chlorophyll in its exposed portion, and
putting out rhizoids from its lower end. The upper extremity bears a tuft

LYCOPODIACE^E

55'

of small leaf-like lobes, beneath which are the archegones and antherids
on the same prothallium, and buried in its tissue. Each antherid arises
from a single superficial cell, which divides by a transverse septum into
an outer stigmatic cell, subsequently splitting up into three, and a basal
cell in which the antherozoids are formed. The archegone has a very
short neck, consisting of three rows of cells. While the prothallium dis-
plays greater differentiation than is the case elsewhere in Vascular
Cryptogams, the embryo or young
sporophyte is, on the contrary, of
very simple structure, and entirely
parenchymatous. A cotyledon is
formed at one end, but there is no
primary root, or other differentiation
of organs. In L. Phlegmaria (L.)
the prothallium is cylindrical, with-
out chlorophyll, and branches freely.
The rhizoids proceed from a super-

FIG. 36. — Prothallium of L. Phleginaria, L. Bifurcate
branch bearing antherids, a, and paraphyses. 2*
(xgo). (After Treub.)

FIG. 37. — Lycopodium clavatutn L.
A , sporangiferous branch (natural size) ;
£, sporange and subtending leaf (greatly
magnified) ; C, spore, showing lines of
fissure (still more magnified).

ficial layer, which also branches laterally, by which means fresh
prothallia are constantly being formed without any production of sexual
organs. The archegones and antherids are borne on the upper surface
of the prothallium, and are always accompanied by paraphyses, barren
tubular cells of rare occurrence among Vascular Cryptogams. The

VASCULAR CRYPTOGAMS

antherids are scattered or in groups, and produce biciliated antherozoids.
The archegones appear later than the antherids on the thickened
extremities of the same branches. They project above the surface of
the prothallium, and have from three to five canal-cells. In the forma-
tion of the sporophyte it is possible that we have a transition between
Vascular Cryptogams and Muscineae. The oosphere divides by a wall
vertical to the axis of the archegone into two cells, of which the one
nearest the neck becomes the suspensor, while the other is the mother-
cell of the embryo. The first root is but slightly endogenous. The cells
of the prothallium of all known species of Lycopodium are liable to be
infested by an endophytic Pythium, the zoospores of which have very
probably been taken for antherozoids. The oophyte of Phylloglossum
is unknown. Of the development of the spo-
rophyte of the Lycopodieae very little is known
in its early stages.

In the typical genus Lycopodium the sporo-
phyte resembles Selaginella in habit. The stem
of most species is procumbent, extending in
the case of L. clavatum (L.) to several feet, and
putting out here and there a few roots into the
soil. Less vigorous branches rise erect, and
are sporangiferous. The procumbent species
display a tendency to bilateralness^especially
in the structure of the axial ' vascular ' bundle.
In other species the much shorter stem grows
erect, and puts out roots from its lower portion,
which in some cases grow downwards through
the tissue of the stem, emerging only as a tuft
at its base. In some of these erect species,
especially in the tropics, the stem is stout and
shrubby. One or two species of Lycopodium
a few are epiphytic.

The sporophyte of Phylloglossum, its only
known condition, has a striking resemblance to the embryonic condition
of Lycopodium. The erect unbranched stem is very short, rising into
a slender scape, which bears at its extremity a spike of sporanges, and at
its base a rosette of long subulate leaves ; otherwise the stem bears
only a few very rudimentary leaves. The plant is reproduced by adven-
titious shoots consisting of a tuber with a leafless rudimentary bud.

As far as has been at present observed, the growing end of the stem
of Lycopodium has no single apical cell, and the same is true of the
leaves and of the roots. The growing point of the stem corresponds

FIG. 38.—.
mondii Kze. /,
/„ old tuber ; t.

'ossum Drum-
aves ; r, roots ;
new tuber : a,

Bo°ierg)ifer°usaxis(X3)'(After have climbing stems;

LYCOPODIACE&

57

closely with that of Gymnosperms. It is composed of a small-celled
primary meristem, in which no differentiation can be detected into

FIG. 39. — Transverse section of stem of L. annotinum. O, epiderm ; A R, outer cortex ; J R, inner
cortex ; S, sclerotised fundamental tissue ; P, vascular bundle-sheath ; H, xylem ; B, phloem-
portion of axial vascular cylinder ; Bsp, leaf-traces (magnified).

58 VASCULAR CRYPTOGAMS

dermatogen and periblem, the rudiments of the c vascular ' bundle
penetrating nearly to its apex. In some species it projects in the young-
est leaves in the form of a low cone ; in others the apex is flat. As in
Flowering Plants, the leaves and rudiments of the shoots do not arise
from single cells, but from groups of cells which include both the outer-
most and the subjacent layers of the primary tissue of the growing point.

The branching of the stem of Lycopodium is either monopodial or
dichotomous in its origin ; but in the latter case one of the bifurcations
usually greatly exceeds the other in vigour of growth. The branches
are never placed in the axils of leaves, as in Flowering Plants, but
usually arise from the stem above a leaf, but without any definite rela-
tion to it. In several species two new growing points of equal strength
appear side by side on the flat apical surface, and continue to de-
velop dichotomously. ( In others the rudiment of the new branch takes
the form of a lateral protuberance on the greatly elevated cone of
growth. On the stems of many species the small leaves are so closely
packed that the internodes are completely suppressed.

The internal structure of the stem of Lycopodiese presents several
peculiarities. The cells of the fundamental tissue are sometimes
uniformly thin-walled, but usually the inner layers in particular have
thicker walls, and the cells are prosenchymatous, or even have their walls
strongly sclerotised, reminding one of the sclerenchymatous layer in
ferns; but they are never coloured brown. The axial * vascular 'cylinder
is separated from the cortical fundamental tissue by a strongly developed
bundle-sheath, composed of from one to three layers of cells. Air-
cavities and mucilage- and gum-passages sometimes occur in the funda-
mental tissue of the stem and the leaves. The ' vascular ' bundles them-
selves present a striking peculiarity in Lycopodium, forming in the stem
and root a single axial cylinder, usually with a circular outline. In this
compound bundle are plates or bands of xylem, which are either com-
pletely isolated, or coalesce in various ways so as to form figures which
are divided into two similar halves by an axial longitudinal section. The
cylinder may therefore be described as displaying a bilateral symmetry.
If transverse sections are made at different heights in the stem, the
xylem presents different figures, in consequence of the bands anasto-
mosing in their course. The elements of these xylem-bands are, like
those of ferns, tracheides pointed at both ends, and increasing in breadth
towards the interior, the most common form of thickening being pitted
or scalariform rather than annular or spiral ; the latter are found only
at the outer edges of the bands. The whole mass of xylem-bands is
surrounded by a narrow-celled phloem, containing, in the larger species,
sieve-tubes. Between the outer edges of the xylem-bands and the

L YCO PODIA CE& 59

periphery lie the bast-like cells known as c protophloem-elements.'
Within the bundle-sheath the phloem is surrounded by several layers of
larger cells, corresponding to the phloem-sheath of ferns. Though the
sclerotised tissue is much less developed than in ferns, the axial ' vascular '
bundle is, in the stouter species of Lycopodium, surrounded by a ring
of fibres composed of several layers. The axial bundle is cauline, and
may be followed out, in a rudimentary condition, to very near the apex.
In Phylloglossum the short stem is traversed by a single narrow bundle,
which is very weak, and has no scalariform, only a few spiral and
annular tracheides.

The roots of Lycopodium originate on the outside of the axial
cylinder ; their internal structure is similar to that of the stem. In the
erect species they have their origin at a considerable height in the stem,
whence they strike downwards through its fundamental tissue, in which
they sometimes even branch dichotomously, and emerge in the form of
a tuft at the base of the greatly thickened stem. In the creeping and
climbing species they emerge separately, and dichotomise in the soil
in intercrossing planes. The epiderm of the root is often strongly
cuticularised. In Phylloglossum the underground portion of the stem
consists of two ovoid tubers of different age (see fig. 38), which are
destitute of the least trace of * vascular ' bundles. From above these
tubers spring a few adventitious roots, which are of endogenous origin,
do not branch, and each of which has a single concentric axial bundle.

The leaves are very small in most species of Lycopodium, and
invariably narrow, simple, and sessile ; sometimes with a long apiculus.
They are sometimes adpressed to the stem with the exception of the free
apex ; more often they are entirely free. In some species the form
and size of the leaves vary greatly even on the same individual plant,
and these heterophyllous species often display more or less of a bilateral
structure. The phyllotaxis is sometimes verticillate, sometimes spiral,
or both arrangements occur together in the same species. In the
verticillate species the leaves are either decussate, or in whorls of three,
four, or more ; on creeping stems they are usually placed on a transverse
zone oblique to the axis ; and the number of leaves in a whorl varies
even on the same branch. The small and extremely variable divergences
of the leaves in the species with spiral phyllotaxis are very remarkable.
Each leaf is always penetrated by a single central ' vascular ' bundle
without any lateral branches ; it is of very simple structure, and is in
connection with the axial cylinder of the stem. In L. albidum (Bak.)
the leaves are membranous, and quite destitute of chlorophyll. The
epiderm is provided with stomates, either on the under surface only or on
both surfaces, and frequently collected into groups. The fundamental

60 VASCULAR CRYPTOGAMS

tissue is sometimes furnished with air-cavities and gum-passages, usually
in connection with the ' vascular ' bundle. In some of the heterophyllous
species these occur only in the sporangiferous or fertile leaves. In
Phylloglossum the leaves all spring from the base of the scape (see fig.
38) ; they are narrow and subulate, about half an inch in length, and pene-
trated by a single ' vascular ' bundle. They are colourless in their basal
half, green in their apical half, and have stomates only in the green part.
In a large number of species of Lycopodium all the leaves serve the
purpose of nutrition only, and the sporanges are borne in the axils of
ordinary leaves. But in the remaining species of Lycopodium, and in
Phylloglossum, the leaves which subtend the sporanges are greatly
modified, being of a membranous texture and colourless. In these
species the sporanges with their subtending leaves are usually collected
into spike-like ' inflorescences,' which may be short, erect, bifurcate
branches, as in L. clavatum, or an elongated naked scape, as in
Phylloglossum.

The sporanges of Lycopodium are seated each on the base of a leaf
which has frequently undergone more or less metamorphosis (see
fig. 37, B] ; by displacement they may subsequently become axillary.
They are kidney-shaped, and are attached at their broader side by a
short thick pedicel. They are unilocular, and dehisce by a fissure across
the apex in the longest diameter. In all the Lycopodiacese the outer
walls of the epidermal cells of the sporange are composed of pure cellu-
lose, while the inner and side walls are lignified. Dehiscence takes
place by the outer face of these cells contracting more than their inner
face in dry air. The small and numerous spores are sphere-cubical, the
exospore being marked in a variety of ways. On germinating the exo-
spore splits by three fissures which meet in a point at the apex of the
spore, the endospore projecting between the three valves thus formed.
The sporange originates as aprominence from a group of superficial cells
at the base of the leaf. The original cells from which it is formed are
few in number ; the central one of these gives rise to the archespore.
The wall of the sporange ultimately consists of from two to four layers
of cells ; the innermost of these forms the layer of tapetal cells. The
mother-cells of the spores become separated from one another, and
invest themselves with very thick cell-walls ; from each is developed
four spores, and the exospore becomes elevated into warts, spines, &c.,
before the walls of the mother-cells have become absorbed. In Phyllo-
glossum the sporanges are also unilocular, and are placed in the axil
of short triangular apiculate metamorphosed leaves ; and a large number
are collected into a spike-like ' fructification ' at the extremity of a naked
scape. They dehisce by a vertical longitudinal fissure. The spores

L YCO PODIA CE& 61

are excessively minute, and have three radiating lines meeting at the
apex. Their germination is unknown.

In most species of Lycopodium vegetative propagation takes place
by means of axillary bulbils, which become detached ; and in some,
adventitious buds are also produced lower down on the stem. L. cer-
nuum produces similar gemmae or bulbils on the root. Phylloglossum
is propagated by the lateral budding of its underground tubers, in a
manner somewhat similar to our native species of Orchis.

The species of Lycopodium are scattered over the whole globe from
the polar to the equatorial regions, the greater number growing on
elevated ground or in swamps ; some are epiphytic. The monotypic
Phylloglossum Drummondii (Kze.) is a native of swamps in Australia and
New Zealand. Several species of Lycopodium have an ancient use as
cathartics. The spores are used in the manufacture of pills, and have
the property, from the large quantity of oil which they contain, of keep-
ing the hands dry when dipped in water. Those of L. clavatum are
collected in large quantities, especially in Northern Germany, for pyro-
technic purposes. The British species are popularly known as ' club-
moss ' and ' stag's-horn moss.'

ORDER 2. — PSILOTE^:.

This order is composed of the two very small tropical genera Psilo-
tum (Sw.) and Tmesipteris (Bernh.), of the latter of which very little is
known, it never having been examined in the living state.

The stem is erect, and is penetrated, in Psilotum, by a cauline
' vascular' bundle of very simple structure, which is circular on transverse
section, and is surrounded by a bundle-sheath. It always branches
dichotomously. Psilotum is entirely rootless, the function of roots
being performed by remarkable underground branches of the stem,
which dichotomise like the aerial shoots. These underground shoots
have a three-sided apical cell, and are entirely destitute of a root-cap.
Those only which are nearest the surface have a few whitish subulate
rudimentary leaves ; these may turn upwards, develop chlorophyll, and
become ordinary aerial shoots. Those branches which strike deeper
into the soil are slenderer, and the rudiments of leaves are reduced to
groups of a few cells which remain buried in the tissue, not projecting
above the surface. They resemble true roots in their single axial
'vascular' cylinder. Psilotum triquetrum (Sw.) produces minute gemmag
or bulbils, which remain dormant for a time, and from which the plant
not unfrequently makes its appearance apparently spontaneously in
orchid- and palm-houses. The leaves of Tmesipteris are erect, elliptical,

62

VASCULAR CRYPTOGAMS

FIG. tf^—Psilctum triqiietrum Sw. A , fertile branch (natural size) ; B, portion of the same
(magnified) ; C, smaller portion and sporange (still more magnified).

LYCOPODIACEyE

63

and apiculate, and are penetrated by a single * vascular ' bundle ; those

which subtend the sporanges are much smaller, and apparently deeply

bifid, in consequence of their becoming connate

at their base in pairs. In Psilotum the leaves

are reduced to mere scales without any 'vascular'

bundle.

The sporanges of the Psilotese differ from
those of the Lycopodieae in not being formed in
connection with the leaves, and in being pluri-
locular. They are collected into spikes which
are formed at the growing point of a primary
shoot. In Tmesipteris each spike usually consists
of two sporanges only, situated in the fork be-
tween two connate or one bifid fertile leaf ; they
are oblong and bilocular, and dehisce by two
vertical slits ; the spores are very minute, oblong,
and curved. In Psilotum the sporanges are col-
lected into groups of three or four
on special short lateral branches,
each in the axil of a rudimentary
leaf, and forming a loose spike.
They are turbinate in form, and
are divided into three compart-
ments, less often into two or four ;
each locule dehisces by a vertical
fissure. The germination of the
spores and the oophyte generation

B

FIG. 41. — Tmesipteris tannensis Bernh. A, por-
tion of branch (natural size); £, sporange
and subtending leaves (magnified).

are entirely unknown in the order.
Psilotum consists of two spe-
cies, natives of the tropical regions of both hemispheres, having the
appearance of small branching nearly leafless shrubs ; Tmesipteris of
a single known species, epiphytic on the trunks of tree-ferns, with a
pendulous habit, in the Southern Hemisphere.

LITERATURE.

Spring— Monograph des Lycopodiacees in Mem. Acad. Roy. Belgique, 1842 and

1849.

Cramer— (L. Selago) in Nageli u, Cramer's Pflanzenphys. Unters. Heft i., 1855.
De Bary — (Germination) Naturf. Gesell. Freiburg, 1858.
Mettenius — (Phylloglossum) Bot. Zeit. , 1867, p. 97.
Payer— Botanique Cryptogamique, 1 868.
Juranyi — (Psilotum) Bot. Zeit., 1871, p. 177.
Hegelmaier— Bot. Zeit., 1872, pp. 798 ef seq., and 1874, p. 773.

64 VASCULAR CRYPTOGAMS

Fankhauser— (Prothallium) Bot. Zeit., 1873, p. i.

Strasburger — Bot. Zeit., 1873, pp. 81 et seq.

Bruchmann— Ueb. Wurzeln v. Lycopodium u. Isoetes, 1874.

Beck— (Prothallium) Oesterr. Bot. Zeitschr., 1880, p. 341.

Bertrand— (Psilotum) Compt. Rend., xcvi., 1883, pp. 390,518; (Phylloglossum) do.,

xcvii., 1883, pp. tp^et seq.
Solms-Laubach— (Psilotum) Ann. Jard. Bot. Buitenzorg, 1884, p. 139, and 1886,

pp. 217, 233.
Treub— (Prothallium) Ann. Jard. Bot. Buitenzorg, 1884, p. 307, and 1886, p. 87;

see Nature, xxxi., 1885, p. 317, and xxxiv., 1886, p. 145.
Galloway— (Spores) Bull. Torrey Bot. Club, 1885, p. 55.
Bower — (Phylloglossum) Proc. Roy. Soc., xxxviii., 1885, p. 445.
Bruchmann — (do.) Bot. Centralbl., xxi., 1885, pp. 23, 309.
Treub— (Prothallium) Ann. of Bot., i., 1887, p. 119.
Goebel— (Prothallium) Bot. Zeit., 1887, pp. 161, 177.

Class IV.— Filices.

Ferns (under which term the Ophioglossaceae are also included in
popular language) are by far the most numerous and best known class
of Vascular Cryptogams. In some families, however, as the Marattia-
ceae and Schizaeaceae, much yet remains to be made out with regard to
the history of development, and their exact position in the -N circle of
affinity must remain for a time doubtful.

The germinating spore develops into the prothallium by the burst-
ing of the cuticularised exospore, and the rapid growth and division of
the contents of the endospore into a plate of cells. Before germination
the contents of the spore become invested with a new cellulose mem-
brane. But the tabular prothallium does not always result directly from
the contents of the spore. In the Hymenophyllaceae the spore under-
goes division, even before the rupture of the exospore, into three cells,
one of which only attains great development, dividing by transverse
septa, and branching until it greatly resembles the protoneme of a
moss ; the flat prothallia then springing from lateral shoots. In most
of the Polypodiaceae, which include by far the greater number of the
genera of ferns, and in the Schizaeaceae, the contents of the spore
develop directly into a short segmented filiform protonemal structure,
which expands at the apex into a cordate or reniform plate of tissue,
consisting at first of only a single layer of cells. If a single apical cell
is present, it soon disappears, and is replaced by a growing point situated
in a depression at the anterior end of the prothallium, behind which a
cushion, several layers in thickness, is formed by tangential cell-

FILICES 65

divisions. The prothallium is most commonly monoecious, though the
sexual organs may not appear at the same time, and is strictly bilateral
or dorsiventral, the result, according to Leitgeb (Sitzber. Akad. Wiss.
Wien, Ixxx., 1880, p. 201), of the action of light. The archegones

FIG. 42. — Germination of prothallium of fern, with exospore still attached, a, b, Dicksonia
antarctica. Lab. (x 240); c, d, Aspidium filix-mas Sw. (x 120). (After Luerssen.)

are found exclusively (except in Marattiaceae) on the under side of the
cushion. Rhizoids are produced in large numbers on the under side
of another part of the cushion ; the antherids also on the under side
among the rhizoids, or less often on the margin. In Gymnogramme

66

VASCULAR CRYPTOGAMS

leptophylla (Desv.) the prothallium is many-lobed, and the archegones
and antherids are produced on separate conical tuber-like outgrowths

from its under side, which penetrate
into the soil, where they are perennial,
and may give birth by budding to new
prothallia, while the sporophyte gene-
ration is annual. The prothallium is
occasionally, in the Hymenophyllaceae,
reduced to a single row of cells ter-
minating in an antherid, or even to a
single cell. Campbell has detected
continuity of protoplasm in the cells of
the prothallium of Struthiopteris ger-
manica (L.). In the Osmundaceae the
prothallium springs directly from the
spore without any intermediate proto-
neme, a plate of cells being formed on
FIG. 43.— Under side of prothallium of germination by longitudinal and trans-

Aneimia Phyllitidis Sw. sk, cushion, .... _

with archegones; a, antherids and rhizoids VCrSC dlVlSlOttS ; the first rhlZOld IS

formed out of a posterior cell. The rib-
bon-shaped prothallium of Osmunda (L.) is characterised by the presence
of a midrib composed of several layers of cells running along its whole

length. The arche-

i j. \

p

gones are produced
on the under surface
on this midrib ; the
antherids either on
the margin or on the
under surface with
the exception of the
midrib. An approach
towards a higher type
of organisation is
indicated by the
tendency of the pro-
thallium to become
dioecious in the
Osmundaceae, and in
Struthiopteris (L.).
All the spores from
the same sporange
'.e. such as bear antherids only, the

FIG. 44. — Antherid of Adiantum capillus-Veneris L., in different
stages. /, prothallium ; a, antherid ; s, antherozoids ; b, vesicle
with starch-grains ( x 500).

sometimes produce male prothallia,

FILICES 67

archegones being produced later, and in smaller numbers, on female pro-
thallia ; or the same prothallium may produce first antherids and sub-
sequently archegones, when it may be termed proterandrous. This is
remarkably the case also in Gymnogramme. In Cystopteris fragilis
(Bernh.) (Polypodiaceae) Campbell states that there are two kinds of
prothallium, a smaller male and a larger hermaphrodite. The prothal-
lium of ferns is sometimes propagated vegetatively by the production of
adventitious shoots from single marginal cells, which become detached
and form independent prothallia. This takes place especially in
Hymenophyllaceae and in Osmunda, but occurs also in Polypodiaceae,

FIG. 45. — Archegone of Adiantum capillus-Veneris, in various stages. A,J3,C, E, in longitudinal,
/?, in transverse section ; h, neck ; j/, canal-cells converted into mucilage ; s, ventral canal-cell ;
e, oosphere ; in E divided into a 2-celled embryo ( x 800). (After Goebel.)

abundantly in Gymnogramme (see Cramer, Denkschr. Schweiz. Naturf.
Gesell., 1880). The prothallium of Vittaria (Sm.) produces peculiar
stalked bulbils.

The antherids of ferns are small papilliform projections on the
under side or margin of the prothallium (very rarely on the upper side),
produced among the rhizoids, and of similar origin, i,e. from a single
superficial cell ; in the Hymenophyllaceae they are produced also on
the protonemal filaments. The protuberance becomes separated by a
septum from the parent superficial cell, and then sometimes divides at
once into the parent-cells of the antherozoids. But more often the

F 2

68

VASCULAR CRYPTOGAMS

papilla divides first of all into a central cell surrounded by a single layer
of peripheral cells. These last are barren, but contain chlorophyll ;
while the central cell divides still further, each derivative nearly cubical
cell then producing a flat spirally-coiled antherozoid contained within a
vesicle, or * special parent-cell.' In no case is the number of anthero-
zoids produced by a single antherid very considerable. The function
of the peripheral cells appears to be to absorb water violently when the
antherid is mature, in consequence of which they swell up considerably
and rupture the central cells, thus causing the escape of the parent-cells
of the antherozoids. From each of these is then discharged, by the bursting
of its delicate cell-wall, an antherozoid consisting of a flat band of proto-
plasm coiled spirally three or four times, and bearing at its anterior end

a number of fine
cilia (fig. 44). To
its posterior end is
frequently attached
for a time a vesicle
containing starch-
grains, which is pro-
bably the remains of
the special parent-
cell of the anthero-
zoid. AS in other
Vascular Crypto-
gams, the body of
the antherozoid ap-
pears to be formed
from the nucleus of
the mother-cell, the cilia from the cell-protoplasm.

The archegones are produced on the under side of the cushion of the
pro thallium, but in much smaller numbers than the antherids. Like
them, each archegone is derived from a single superficial cell, which at
first bulges only slightly, and is first divided into three cells by two
tangential walls. The lowermost of these three, or basal cell, divides
further, and takes its share in the formation of the venter, or swollen
part of the archegone, which is altogether imbedded in the prothallium.
The outermost of the three cells develops into the neck-wall, or outer-
most wall of the neck of the archegone, dividing at first into four cells,
from which the four rows of cells which constitute the neck are formed
by oblique septa. Since the neck grows more rapidly on the anterior
side, i.e. the side nearest to the apex of the prothallium, and hence
becomes convex on that side, the number of cells is also larger in the

FIG. 46. — Archegone of Pteris serrnlata L. at the moment of the
expulsion of the mucilage ( x 350). (After Strasburger.)

FILICES 69

anterior rows of the neck, the usual number being six, while there are
seldom more than four in the concave posterior side. From the middle
one of the three primary cells arises the whole of the axial row of cells
of the archegone, consisting of the central cell and the canal-cells.
During the development of the neck this middle cell becomes pointed
upwards, and forces itself between the neck-cells ; this pointed portion
becomes divided off by a septum, and now forms the single neck-canal-
cell, which lengthens as the neck lengthens. The large central cell now
breaks up into an upper and smaller ventral canal-cell and a much
larger lower cell, the protoplasmic contents of which subsequently
become rounded off, and constitute the oosphere. According to Campbell,
the ventral canal-cell is wanting in Struthiopteris germanica (L.). The
walls of the canal -cells swell up and become converted into mucilage,
and finally this thin mucilage, together with the protoplasm of the
canal-cells, is expelled from the open neck. The antherozoids are
retained by the mucilage, and collect in large numbers before the
archegone ; a number of them force themselves into the canal of the
neck, and of these some eventually reach the oosphere, and coalesce
with it, entering it at a light-coloured spot near the neck, which is
termed the receptive spot. After impregnation the neck closes up. It
is very rare for more than one archegone to be fertilised on the same
prothallium, and the enormous majority of prothallia perish without
producing any sporophyte generation.

The ordinary course of the alternation of generations is occasionally
interrupted by apogamy or by apospory, the suppression respectively of the
oophyte or of the sporophyte generation. The former has been observed
especially in Pteris serrulata (L. fil.), the laiter in particular varieties of
Athyrium nlix-fcemina (Bernh.), and of Polystichum angulare (Willd.). In
apogamy the non-sexual fern-plant springs directly from the prothallium
without the intervention of a fertilised archegone. In apospory a pro-
thallium is produced on the surface of the frond, either in the locality
where the sorus would normally be found, or less often elsewhere, and
may assume unusual forms, sometimes that of a solid cylindrical body,
but bears normal archegones and antherids. Bower classifies the
various forms of substitutionary or correlative growths connected with
the suppression of the sporophyte generation under three heads, viz. —
(i) simple prolification ; (2) sporophytic budding; (3) apospory. The
first hardly occurs among ferns. The second is illustrated by the
familiar formation of bulbils in species of Asplenium (L.), Cystopteris
(Bernh.), &c., in which the formation of the buds cannot be directly corre-
lated with arrest of spore-formation. In apospory we get a more or less
complete sporal arrest, but this may vary in degree. In some instances

70 VASCULAR CRYPTOGAMS

the substitutionary growths which accompany the arrest of spore-forma-
tion are restricted to the sporanges themselves. These are replaced by
' pseudo-bulbils ' of a pear-like form, presenting but little resemblance to
ordinary prothallia, but demonstrating their oophytic character by pro-
ducing antherids. In other examples the prothalloid growths are by no
means restricted to the sporange ; they may either arise from the sorus
itself, or may appear at points quite distinct from the sori, and even on
fronds which bear no sori at all. There is here a distinct transition from

arch

FIG. 47. — Apogamous shoot of Pteris serrulata, on the
under side ot the prothallium/ ; b, first leaf; z>, apex of
stem ; iv, rudiment of first endogenous root ( x 80).
(After de Bary.)

FIG. 48.— Prothalloid growth of Poly-
stichum angulare Willd. var. pul-
cherrima, originating from surface
of frond ; arc/i, archegone ( x 10).
(After Bower.)

sporophyte to oophyte without the intervention of spores. Compara-
tively little is known about the oophyte generation in the Hymeno-
phyllaceae, but it would appear as if apogamy were a very common,
perhaps even normal occurrence in some species of Trichomanes (Sm.) ;
and here the two phenomena have even been observed on the same indi-
vidual, the oophyte and sporophyte generation succeeding one another
without the production of either spores or sexual organs.

The fertilised oosphere or .oosperm becomes immediately invested

FILICES

7i

with a cell-wall of its own, and develops by cell-division into the
embryo, from which springs the young sporophyte, commonly known as
the fern-plant. The first division-wall in the oosperm is always nearly
vertical ; and two others follow, at right angles to it and to each other,
dividing the oosperm into octants. From the anterior of the two original
halves are derived the growing point of the stem, and the cotyledon or first
leaf; from the posterior half the/00/ by which it is attached to the prothal-
lium, and the first root. Until the differentiation of the first leaf and the
fixed root, the embryo remains imbedded in the surrounding tissue of
the prothallium, which grows with its growth. The primary root is
always small ; in the Hymenophyllaceas it disappears early, and in many

FIG. 49. — Asplenium decussatum ; adventitious bud, k,
already rooting (natural size).

FiG. 50. — Young sporophyte of
Adiantum capillus-Veneris still
attached to prothallium / ; b,
first leaf ; w', w", ist and 2nd
root ; h, rhizoids of prothallium
( x 30). (After Goebel.)

species of Trichomanes no subsequent roots are formed, their place
being supplied by underground branches.

The mature fern varies in size from that of the 'filmy ferns,' species
of Hymenophyllum not above an inch in height, with delicate moss-
like habit, to the stately ' tree-ferns ' of the Southern Hemisphere
(Cyatheaceae and Dicksonia, L'Herit), fifty or sixty feet in height. The
stem is either ascending and vertical, or creeping on or beneath the
surface of the soil, or occasionally scandent (Lygodium, Sw.), often very
short with undeveloped internodes, and the leaves so crowded that fre-
quently no portion of the stem — then often called a caudex — remains
exposed ; while in the creeping and climbing species the leaves are often

72 VASCULAR CRYPTOGAMS

separated by long mternodes. The ultimate roots are always adventi-
tious ; that is, there is no predominant axial root which is a prolongation
downwards of -the main axis of the plant, as in many Dicotyledons and
some Monocotyledons. They are usually very numerous, especially in
tree-ferns, arising in acropetal succession, and completely clothing the
lower part of the stem, or, where this is suppressed, the leaf-stalks, as in
the case of the common ' male fern ' (Aspidium filix-mas, Sw.). The
ultimate branches of the root are furnished with a root-cap as in Flower-
ing Plants. The leaves, or, as they are more commonly called, ' fronds,'
are invariably stalked, and are remarkable in many species, especially
when they attain a large size, for the great extent to which subdivision
of the lamina is carried ; in some tree-ferns they attain a length of from
six to ten feet. In the filmy ferns they consist, as in Muscineae, of only
a single layer of cells penetrated by distinct ' vascular' bundles. Stomates,
similar in structure to those of Flowering Plants, occur abundantly both
on the under side of the leaf and on the leaf-stalk, except in the
Hymenophyllacese. The leaves exhibit very little metamorphosis com-
pared to those of Flowering Plants. Most usually all the leaves are alike
in form and extent of division, and even nearly so in size ; but in some
species only certain of the leaves, sporophylls^ are fertile, and these then
show a more or less well-marked difference from the barren leaves, as in
our 'hard fern ' (Lomaria spicant, Desv.)and 'parsley fern '(Cryptogramme
crispa, R. Br.). In the ' elk's-horn fern ' (Platycerium alcicorne, Desv.),
commonly grown in cultivation, the leaves are alternately broad thallus-
like barren plates, closely applied to the surface on which the plant
grows, and long erect dichotomously branched fertile leaves. The
leaves (except the first, which spring from the prothallium) are cirdnate
in vernation, both the principal rachis and the midrib of the pinnae
(when the leaf is pinnate) being rolled up on their upper side — owing to
the more rapid growth of the cells on the under than those on the upper
surface — and only slowly unroll as the development of the leaf advances.
The young leaves, and the rachis and petiole of mature leaves, are
generally more or less completely clothed with pales or ramenta, flat
brown scale-like trichomes or outgrowths of the epiderm. These are
often glandular, and sometimes contain crystals of oxalate of lime. They
serve as a protective mantle to the young stem and leaves, and also as a
reservoir of moisture. Capitate, glandular, and other more ordinary
kinds of hair are also of frequent occurrence. In the typical ferns the
sporanges are also trichomic in their origin. They are collected into
groups or sort (fig. 58), usually formed in connection with a 'vascular '
bundle. In unilamellar leaves these sori are placed on the edge, in all
others almost invariably on the under side of the leaf, especially of its

FILICES

73

apical portion, and they then assume a great variety of shapes — circular,
reniform, crescent-shaped, linear, or they are concealed beneath the
revolute margin of the leaf. The sorus may or may not be covered by
a membrane called the indusium, an outgrowth of the epiderm. In the

FIG. 51. — Asplenium Adiantum-nigrum L. ; rhizome with fronds showing Circinate

Asplenitun Adiantum-nigniin L. ; rhizome with fronds showing drcii
irnation (natural size), a, under side of fertile pinnule (magnified).

Cyatheacese they assume the form of a cup ; in the Hymenophyllaceae
they are situated at the extremity of a vein at the apex or margin of a
pinna. In some instances, as in our native ' flowering ' or ' royal fern '
.(Osmunda regalis, L.), the sori completely consume, in the course of their

74

VASCULAR CRYPTOGAMS

development, the parenchyme of the fertile (apical) part of the leaf,
giving the appearance of a panicled or thyrsoid inflorescence. The
sporange is usually stalked, and has an elliptical form, or that of a battle-
dore or racket-bat. The sides are commonly thin and membranous, and
the sporange dehisces either longitudinally or transversely, generally from
the elasticity of an annulus or ring of brown thick-walled cells running
along or across it. The position of this annulus, and its more or less
complete development or entire absence, are useful characters in the
subdivision of the class. In the Marattiaceae the sporanges are of
altogether different origin, being developed from hypodermal masses of
cells ; and transitional forms occur between the two. The spores are

minute, very commonly re-
niform, or often nearly
cubical, resembling pollen-
grains in structure, usually
furnished with two coats,
an exospore and endospore,
the latter of which is some-
times double, and the
former generally marked
with papillae, reticulations,
&c.

A more minuteAdescrip-
tion must now be given of
the structure and peculi-
arities of the various organs.
The great distinguishing
feature which characterises
the development of the
stem of ferns, as contrasted
with that which occurs in
all Flowering Plants (Gym-
nosperms and Angiosperms), is the presence of a single apical cell,
from which the whole of the growing point or apical meristem origi-
nates, and which may therefore be recognised as the parent-cell of the
whole of the tissue subsequently formed. This apical cell is usually
wedge-shaped in creeping stems with a bilateral structure, a three-sided
pyramid in erect or ascending stems. The growing apex of the stem is
frequently completely hidden in the youngest leaf-bud, but in other species
there is a considerable intervening space. In some Hymenophyllaceae
leafless prolongations of the stem assume the appearance and the funccion
of roots. As contrasted with Flowering Plants, especially Exogens, the
stem of ferns is characterised by the small extent to which it branches ;

FIG. 52. — Diagram of tip of leaf of Cerate
troides Brongn. S, apical cell ; L, latera;
(After Kny.)

">teris thalic-
lobe of leaf.

FILICES

75

and this is true not only of the erect columnar stem of tree-ferns, but
also of the creeping or erect stem of smaller species. Axillary branch-
ing is very rare, if it ever actually occurs ; the terminal branching is
always dichotomous, never sympodial. The fundamental tissue of the
stem and leaf-stalk consists, in many species, entirely of thin-walled
parenchyme. In others, and especially in tree-ferns, portions of it
undergo a change in the great thickening and brown colouring of the
cell-walls, the cells becoming at the same time prosenchymatous. In

this sclerenchyme of
the fundamental tis-
sue the sclerosis
take place in

FIG. 54. — Transverse
section of stem of
Pteris aquilina L.
T, epiderm ; p, fun-
damental tissue ; pr,
sclerenchymatous
sheath ; ig, vascular
bundle ; ag", outer
network (somewhat
magnified).

individual isolated
cells ; more often

FIG. 53. — Transverse section of 'vascular' bundle of Polypodiitm
leiorhizum Wall, p, fundamental tissue ; s, sclerenchymatous the CCuS SO
sheath ; *, phloem ; h, xylem ( x :

spicuous bands or sheaths. In many Polypodiaceae and Osmundacese
the entire cortex assumes eventually a dark colour. In the common
brake (Pteris aquilina, L.) two thick sclerenchymatous bands of this
description lie between the inner and outer 'vascular' bundles,
while another continuous layer immediately underlies the epiderm.
The firmness and solidity of the stem of tree-ferns are mainly due to
strongly developed sclerenchymatous cylinders which form complete
sheaths surrounding the 'vascular' bundles. The ' vascular ' bundles
themselves are always dosed or destitute of cambium ; in the stem,
except in Osmunda, and usually in the leaves, they are concentric^ consist-
ing of a central xylem-portion entirely enveloped in a layer of phloem ;
in, the stem and leaves of Osmunda, and in the leaves of some other
ferns, they are collateral^ the xylem and phloem portions lying side by

76 VASCULAR CRYPTOGAMS

side. Besides a few narrow spiral tracheides, lying at definite points
of the transverse section, the xylem consists mainly of scalariform
tracheides^ i.e. of tracheides with bordered pits which usually have the
appearance of transverse clefts, their ends being mostly obliquely trun-
cate or fusiform and pointed. True vessels occur but rarely in ferns ;
e.g. in Pteris aquilina and in the rhizome of Athyrium filix-fcemina,
where they are also scalariform. Between the tracheides lie narrow
thin-walled cells which contain starch in winter. In the phloem, in
addition to narrow parenchymatous cells, are sieve-tubes with well-
developed sieve-plates, but forming true callus only in a small number
of cases ; and at the circumference narrow bast-like thick-wall prosen-
chyme. Each individual bundle is usually immediately enclosed in a
single distinct layer of narrower cells, the vascular bundle-sheath or
endoderm ; this layer, which probably originates from the fundamental
tissue, displays a strong tendency for its walls to become brown and
suberised. In very young stems and those which permanently remain
very slender, as in many Hymenophyllacese, there is a single axial
bundle. But in stouter stems and leaf-stalks the central bundle is re-
placed by a network of anastomosing bundles, presenting, in typical
cases, a cylinder of considerable diameter, by which the fundamental
tissue is separated into an outer cortical and an inner medullary portion ;
but isolated scattered bundles also arise in addition. The principal
bundles which constitute this cylindrical network mostly have the form
of broad plates with the margins curved outwards, each surrounded by
its thick firm brown sclerenchyme-sheath ; they usually present the
appearance of an interrupted ring near the periphery, but in Osmun-
daceae the ring is more continuous. From the margins of these cauline
bundles spring the more slender filiform bundles which pass into the
leaves, the number of openings in the meshes of the cauline 'vascular'
cylinder corresponding to that of the leaves. In the leaf-stalk the
bundles may either run separately or may coalesce into plates. Ter-
letzki (Pringsheim's Jahrb., 1884, p. 452) has detected continuity of
protoplasm between the cells in the parenchyme of the rhizome in
several species of fern ; the intercellular spaces also contain protoplasm
which is in connection with that of the cells. In the aquatic genus
Ceratopteris the stem contains large air-cavities. Elongated tannin-sacs
occur in the parenchyme of the stem and leaf-stalk of many ferns,
especially in the neighbourhood of the ' vascular ' bundles. Gum- and
mucilage-cells are also of frequent occurrence. Incrustations of cal-
cium carbonate are not infrequent on the leaves. Round stalked glands
occur in the fundamental tissue of the stem and leaves of Aspidium
filix-mas.

FILICES 77

The leaves of ferns stand either in two rows on the stem, or less
often in a single dorsal row, or the phyllotaxis is more complicated and
spiral ; they are never opposite or whorled. Each leaf originates from
a superficial cell of the growing point distinguished by a stronger swell-
ing of its outer cell-wall. The petiole is the first part of the leaf
formed ; the lamina then begins to appear at its apex, and itself
develops from the base to the apex. In many ferns the leaves of the
mature plant are characterised by the extraordinary slowness of their
development. In old plants of Pteris aquilina the formation of the leaf
commences fully two years before it begins to unfold ; at the com-
mencement of the second year only the leaf-stalk is as yet in existence ;
during the summer of the second year the lamina begins to develop at
the apex of the rod-like petiole, and may be found hidden beneath the
long hairs in the form of a minute disc. It then begins to bend down-
wards at its apex, and continues for a time in a pendent condition. It
is only in the spring of the third year that the elongation of the leaf-
stalk forces the lamina above the surface of the soil, and that the latter
begins to unfold. In Aspidium filix-mas the development is almost as
slow. The basifugal development of the lamina itself is also extremely
slow in many ferns, the lower portions having long been fTHly formed
while the apex is still unfolding. In several genera, as Gleichenia (Sm.)
and Mertensia (Willd.), a periodical interruption occurs of the apical
growth, this intermittent development even extending over several years.
In Lygodium the primary pinnae remain unfolded after the formation of
a pair of pinnae of the second order, while the rachis of the leaf grows
without limit and resembles a twining stem, climbing in some cases to
the height of fifty or one hundred feet, the pinnae themselves presenting
the appearance of leaves. In the anomalous Ceratopteris thalictroides,
which grows in water, the ultimate segments of the leaves are swollen
up in a pod-like manner. Goebel has shown (Ann. Jard. Bot. Buiten-
zorg, vii., 1887) that in the heterophyllous ferns, such as Platycerium
alcicorne and several species of Polypodium (L.), one form of leaf is
specially adapted, directly or indirectly, for the supply of nutriment to
the plant, and is sometimes furnished with special aquiferous tissue.
The stipular structures of the Marattiaceae are quite peculiar among
Vascular Cryptogams. The leaves of ferns not unfrequently display a
tendency to branch dichotomously at the apex, but in other cases the
branching appears to be monopodial. The leaf-stalk has frequently the
power of producing adventitious leaf-buds (see fig. 49). In Struthiopteris
germanica these develop into long underground stolons covered with
scale-leaves, which at length rise above the surface, and bear at their
apex a rosette of ordinary leaves. Nephrolepis (Sch.) is also furnished

78 VASCULAR CRYPTOGAMS

with remarkable stolons, the extremities of which swell up into tubers ;
but it is uncertain whether they belong to the stem or the root. In
other cases adventitious leaf-buds are borne on the upper surface of the
lamina or in the axils of the leaves. In Woodwardia radicans (Sm.) and
some other species, the long drooping leaves may root in the soil and
put up new shoots. The veins in the leaves of the great majority of
ferns do not anastomose, but divide repeatedly dichotomously. Their
1 vascular ' bundles differ, in some cases, from those of the stem in being
collateral, the xylem facing the upper, the phloem the under surface of
the leaf.

With the exception of some species of Trichomanes, all ferns have
true roots, characterised, like those of Vascular Cryptogams generally,
and of Flowering Plants, by the presence of a true root-cap, composed of
several layers of cells, and by the tendency of the epidermal cells to
develop into long unsegrnented filaments or root-hairs, by which the
nutriment is absorbed from the soil. These proceed in acropetal suc-
cession from the creeping underground stem or rhizome, or, where the
stem is erect, very short, and densely covered with leaves, from the leaf-
stalks. In tree-ferns the lower part of the erect stem is densely covered
with a thick felt-like envelope of slender roots, which give a broad base
to the stem. Like the stem, the tissue of the root develops from a
single apical cell. The branching is always monopodial. The lateral
rootlets arise in acropetal succession on the outside of the primary
'vascular' bundle. The root is traversed by a single axial cylinder
formed by the coalescence of ' vascular ' bundles.

The epiderm of the leaves of those ferns which are not unilamellar
differs in no essential respect from that of Flowering Plants, but its cells
contain a larger quantity of chlorophyll. The epiderm of the under
side only is abundantly provided with stomates, which are usually of
quite the ordinary structure. In some cases, as Aneimia (Sw.), they
present the peculiar appearance of the two guard-cells being entirely
enclosed within a single epidermal cell. Those of Kaulfussia (Bl.)
(Marattiaceae) are very large, and of peculiar structure.

The sporanges of ferns are rounded, ovoid, or pear-shaped capsules,
seated on long stalks in the Polypodiaceae and Cyatheaceae, sessile in
the other orders. When mature, the wall of the capsule consists,
except in the Marattiaceae, of a single layer of cells, a particular row of
which, running longitudinally, transversely, or obliquely round the
capsule, usually undergoes special development, and is known as the
annulus ; but the annulus may be entirely wanting, as in the Marat-
tiaceae, or its place may be taken by the special development of an
apical or lateral group of cells, as in the Osmundaceae. Where there is

FILICES

79

an annulus the sporange dehisces by a fissure at right angles to it ; in
the Marattiacese it opens by an apical pore. The dehiscence is due to
unequal contraction in drying of the unequally thickened portions of
the cell-walls of the annulus. On one side of the sporange of a
considerable number of ferns are two, three, or four cells of peculiar form,
with lignified cell -walls, the lip-cells, between which the dehis-
cence always begins, and which ap-
pear to guide its direction. These /
cells together are sometimes called
the ' stomium.' Among the spo-

FIG. 55. — Sporange of Aspidium filix-
mas, showing annulus an, lip-cells
/c,and paraphyse attached to stalk.
(After Kiindig, greatly magnified.)

ranges are frequently slender seg-
mented filaments, or paraphyses.

Tn snmp PnlvnnHiarp^ thprp is „ FIG. 56.— Development of sporange of

OiypOQiace S a niwn Trichomanes L. s, archespore ; r,

single (rarely more than one) out- annulus ( x 55°>- (After Goebei.)
growth from the stalk of the sporange, resembling a capitate hair, and
sometimes septated internally. It is regarded as a paraphyse, and may
probably be an undeveloped sporange. The entire sorus may be
covered by the recurved margin of the leaf, or by a true indusium
belonging to the epiderm, or by a false indusium, consisting of an
outgrowth of the hypodermal tissue, composed of several layers of cells.
In Enterosora (Bak.), from British Guiana (Polypodiaceas), the sporanges
spring from the base of spherical chambers in the under surface of the

8o VASCULAR CRYPTOGAMS

leaf, which open only by a narrow slit. Although the sori usually
originate on the veins of a leaf, and only on the under side of the
lamina, this is not always the case. In Olfersia they spring from both
surfaces of the lamina by the side of the midrib ; and in this and other
species of Acrosticheae from the mesophyll as well as the veins. In the
Hymenophyllaceae they are enclosed in a cup-like indusium, and are
attached to the apex of the veins, which projects beyond the margin of
the leaf. The spot on the fertile vein which bears a sorus is known as
the placenta or receptacle. In the Polypodiaceae, and probably also in
the Cyatheaceae, each sporange originates from a single epidermal cell,
which swells up considerably, and is cut off from the rest of the leaf
by a septum. This mother-cell of the sporange subsequently divides
by another septum into a basal cell which develops into the pedicel,
and an apical cell which becomes the capsule. The pedicel usually
consists ultimately of three rows of cells produced by longitudinal and
transverse divisions. The nearly hemispherical mother-cell of the
capsule first divides, by four successive oblique walls, into four parietal
and a nearly cubical central cell, the archespore. In the parietal cells
further divisions follow at right angles to the surface ; while from the
archespore are formed four tabular segments parallel to the parietal
cells, which again divide by walls vertical to the surface into one or two
layers of tapetal or mantle-cells, constituting together the tapete. The
row of cells in the wall of the sporange which constitute the annulus are
the result of divisions at right angles to the surface of the sporange ;
their outer walls bulge out and project above the surface. The tapetal
cells ultimately disappear, and the whole of the space within the wall of
the capsule is occupied by a fluid, in which float the mother-cells of the
spores formed by successive bipartitions of the archespore, and nor-
mally sixteen in number in the Polypodiaceae and Schizaeacese. In these
families the formation of the spores takes place in the following way.
Each of the sixteen spore-mother-cells divides into four by two succes-
sive bipartitions of the protoplasmic contents, preceded by correspond-
ing divisions of the nuclei. Sixty-four spores are thus normally formed
in each sporange. They then invest themselves with a cell-wall, which
is usually double, consisting of an inner coat, or endospore, generally
but not always composed of cellulose, and sometimes itself consisting of
two layers, and an outer brown cuticularised exospore, provided with
ridges, papillae, warts, or other elevations. Leitgeb states that in
Osmunda and some other genera there is no true endospore ; while in
Onoclea (L.), according to Campbell, there are three coats. The spores
of the Osmundaceae and Hymenophyllaceae contain chlorophyll.
Another mode of spore-formation, more analogous to what takes place

FILICES 8 1

in the formation of the pollen of Flowering Plants, occurs sometimes in
the two orders just named, and invariably in the Cyatheaceae, Osmun-
daceae, and Hymenophyllaceae. Each spore-mother-cell divides at once
by cell-walls of cellulose into four compartments, sometimes called
' special mother-cells ' ; within each of these compartments the spores
become invested with their permanent cell-walls, both the walls of the
original mother-cells and their septa being then absorbed. The spores
formed in this way have a rounded cubical shape, while those produced
in the mode first described are bilateral, and very commonly kidney-
shaped. In the Schizaeacese and Osmundaceae the sporanges are not
strictly trichomic in their origin, being formed, before the differentiation
of the epiderm, each from a single cell, which may be regarded as the
rudiment of a leaf-branch. In both these orders the number of spores
produced in a sporange is much larger than in the Polypodiaceae ; in
this and in other respects they manifest an approximation to the Marat -
tiaceae and Ophioglossaceae. The sporanges of Marattiaceae are alto-
gether endogenous in their origin, being developed from an internal
mass of tissue, and are destitute of an annulus. On the dehiscence of
the normal sporange the spores are at first attached to the annulus, and
are detached and thrown to a distance by its sudden return to its
original position. The spores of many Polypodiaceae retain their vitality
and power of germination for a long period, and require a longer or
shorter period of rest before germination ; those of the Hymenophylla-
ceae, on the other hand, often begin to germinate while still enclosed in
the sporange. In Scolopendrium (Sm.), according to Beck (Verhandl.
Zool.-Bot. Ges. Wien, 1879), the exospore does not burst, but decays at
the spot where the germinating filament emerges.

The non-sexual propagation of ferns takes place chiefly by means of
the adventitious buds already described, which appear on the lamina or
petiole of the leaf (fig. 49). As a normal phenomenon it is, however, con-
fined to a small number of species known in cultivation as viviparous or
bulbiferous ferns, such as Asplenium bulbiferum (Forst.) and Cystopteris
bulbifera (Bernh.). The occasional vegetative propagation of the
prothallium has also been already described.

Ferns are distributed over the whole globe, from the equator to the
arctic zone ; and, from the ease of their culture and the beauty of their
forms, are favourite objects of cultivation. They are most abundant in
moist warm climates, and hence enter largely into the composition of all
insular floras. In the tropics a large number of species are epiphytic ;
and it is only there, and in the islands of the Southern Hemisphere, that
they attain the size of tree-ferns. One or two species are annual, and a
single one, Ceratopteris thalictroides, is aquatic, while a very few have a

G

82 VASCULAR CRYPTOGAMS

climbing habit. The number of species which are at the present time
applied to any economical purpose is extremely small. The common
brake, Pteris aquilina, is largely used throughout Northern Europe for
forage purposes, and for the stuffing of rough beds and pillows. The so-
called ' male fern,' Aspidium filix-mas, has a very ancient repute as a
vermifuge, and is still occasionally employed for that purpose, as also are
several other species to a less extent in different parts of the globe, either
for a similar purpose or as astringents and mucilages. In several species,
especially tropical, the stem contains sufficient starch to be esculent.
The number of known species of ferns is at present estimated at about
3,000, but it is constantly and rapidly increasing. They are arranged in
a comparatively small number of genera, the limits of which are often
extremely difficult to define.

LITERATURE.

Mettenius — Filices Hort. Bot. Lipsiensis, 1856.

Hofmeister — Abhandl. Sachs. Gesell. Wiss., vol. v., 1857 ; and Pringsheim's Jahrb.

wiss. Bot., 1863, p. 278.
Wigand — Botanische Untersuchungen, 1854.
Newman — History of British Ferns, 4th ed., 1865.
Reess — (Sporange) Pringsheim's Jahrb. wiss. Bot., 1867, p. 217.
Strasburger — (Fertilisation) ibid., 1869, p. 390.
Kny— (Antherid) Monber. Akad. Wiss. Berlin, 1869, p. 416 ; and Pringsheim's

Jahrb. wiss. Bot., 1869, p. i.
Hooker and Baker— Synopsis Filicum, 1868.

Goebel — (Prothallium of Gymnogramme) Bot. Zeit., 1877, pp. 671 et seq.
Weiss— (Bundle-sheath) Flora, 1880, p. 119.

Cramer— (Fertilisation) Denkschr. Schweiz. Naturf. Gesell., 1880.
Haberlandt — (Vascular Bundles) Sitzber. Akad. Wiss. Wien, Ixxxiv. , 1881, p. 121.
Lachmann— (Root-organs) Compt. Rend., xcviii., 1884, p. 833 ; and ci., 1885, p. 592.
Klein— Bot. Zeit., 1884, pp. 577 et seq.
Schmidt— (Dehiscence of Sporange) Flora, 1885, pp. 451, 471, and 1887, pp. 177,

202 ; and Ber. Deutsch. Bot. Ges., 1886, p. 396.
Campbell— (Prothallium) Bot. Gazette, 1885, p. 355.
Thomae— (Leaf-stalk) Pringsheim's Jahrb. wiss. Bot., 1886, p. 99.
Goebeler— (Pales) Flora, 1 886, pp. 451 et seq.
Gardiner and Ito— (Mucilage-cells) Ann. of Bot., i., 1887, p. 27.
Campbell — (Struthiopteris germanica) Mem. Boston Soc. Nat. Hist., 1887, P- 17>
Kiindig— (Sporange) Hedwigia, 1888, p. I.

The following classification of the Filices into families or orders
follows partly the plan proposed by Mettenius, partly that adopted in
Hooker and Baker's * Synopsis Filicum.' It must, however, be distinctly
borne in mind that the divisions are of very unequal value. The first
three are closely allied to one another ; the Hymenophyllaceae show con-

FILICES 83

siderably greater divergence ; the affinity of Osmundaceae and Schizaeaceae
with the typical ferns is more remote ; while the Marattiaceae exhibit so
many points of divergence that some high authorities have removed
them altogether from the Filices.

ORDER i. — POLYPODIACE^E.

This order includes by far the largest number of genera and species,
and may be regarded as the typical family of ferns. The sporanges
arise out of single epidermal cells, and have usually long pedicels ; they

FIG. 57.— Alsophila aculeata Klotzsch, a tree-fern (reduced).

have an incomplete vertical annulus, and consequently dehisce trans-
versely. The sori vary greatly in size and form, and usually consist of
a large number of sporanges. They are seated on the under side of the
divided or undivided leaf, upon the veins ; much less often (Acrosticheae)
also on the upper surface or in connection with the mesophyll ; they
are usually covered by an indusium in the Asplenieae, Aspidiese, and
Davallieae, but not in the Acrosticheae or Polypodiese. In the great
majority of species all the leaves are ultimately fertile; but in some genera
(Gymnogramme (Desv.), Lomaria (Willd.), Platycerium (Desv.), &c.)

G 2

84

VASCULAR CRYPTOGAMS

there are species with barren and fertile leaves, differing from one
another in habit and in degree of segmentation ; in other heterophyllous

FIG. 58.— Sori of Polypodiaceac (variously magnified), a, b, Adiantunt ; c, Lindsaya ; <i, e, Blechnum ;
f*g> Cystopteris ; h, i, Da-vallia ; k, /, Cheilanthes ; tn, «, Pteris ; o,fl, Woodwardia ; q, Scolopen-
drium; r, s, Asplenium; t, Aspidium ; u,v} Woodsia; w, Gymnogramme ; x, z, Polypodium.
(After Luerssen.)

ferns (species of Polypodium) both forms of leaf are fertile. A few of
the Polypodies are arborescent (Dicksonia L'Herit).

FILICES

85

Principal genera : — Adiantum (L.), Cheilanthes (Sw.), Pellaea (Link),
Pteris (L.), Lomaria (Willd.), Blechnum (L.), Woodwardia (Sm.), Doodia
(R. Br.), Asplenium (L.), Scolopendrium (Sm.), Aspidium (Sw.), Nephro-
dium(Rich.), Lastrea (Presl), Nephrolepis (Sch.), Polypodium(L.), Notho-
clsena (R. Br.), Gymnogramme (Desv.), Hermonitis (L.), Vittaria (Sm.),
Acrostichum (L.), Platycerium (Desv.), Onoclea (L.), Woodsia (R. Br.),
Ceterach (Adans.), Dicksonia (L'Herit.), Davallia (Sm.), Cystopteris
(Bernh.), Lindsaya (Dry.).

with open indusium (mag-

ORDER 2. — CYATHEACE^E.

This order is not distinguished from the Polypodiaceae by any very
clear lines of demarcation. The sporanges are epidermal and shortly
stalked ; they have a complete oblique eccentric annulus. The sori
are seated on a receptacle or placenta which often projects consider-
ably ; they are naked, or are more often enclosed in
a cup-shaped indusium or ' involucre,' which some-
times forms a closed cup opening by a transverse
fissure ; the sporanges are densely crowded in the
sorus. The greater number of the tree-ferns
belong to this family (fig. 57). The leaves are
often very large (five to ten feet in length), and
usually compoundly pinnate, forming a rosette at the summit of the
columnar unbranched arborescent stem, which is densely covered
with aerial roots, especially in its lower portion, and is marked in a
diamond pattern by the scars of fallen leaves. In some species, in
addition to the ordinary cylinder of 'vascular' bundles, there are a
number of accessory bundles distributed through the medulla and
cortex, forming a delicate open network. Crystals of calcium oxalate
are not uncommon in the epidermal cells.

Principal genera : — Cyathea (Sm.), Hemitelia (Br.), Alsophila (R. Br.).

ORDER 3. — GLEICHENIACE^E.

The sporanges are epidermal and sessile, with a
broad complete transverse annulus running nearly hori-
zontally, and hence with vertical dehiscence. The sori
are naked, on the under side of ordinary leaves, and
usually consist of only three or four sporanges. The
stem is a slender creeping rhizome ; the leaves are usually
very large, and with peculiar buds or ' innovations ' on
the lamina.

Principal genera : — Gieichenia (Sm.), Mertensia (Willd.).

,

FIG. 60.— Sporan^e

of Gieichenia
(mas"ified>'

86

VASCULAR CRYPTOGAMS

ar,

ORDER 4. — HYMENOPHYLLACE^E. .

The oophyte generation is known but in a very few species of
Hymenophyllaceae, Where it has been observed (some species of
Hymenophyllum and Trichomanes) it differs from that of other ferns,
and is usually filiform, closely resembling the protoneme of a moss, but
somewhat coarser. Antherids appear to be produced at the middle of
these filaments, and archegones at their extremity. But apogamy is
much more common in the Hymenophyllaceae than in any other family
of ferns, and it is doubtful whether it does not even occur regularly in
some species. Bulbils or gemmae are produced abundantly on the pro-
thallium, consisting of a small number of cells, and borne on pedicels
or sterigmas. They germinate with extreme slowness. In Trichomanes

pyxidiferum (L.) the prothallium is
frequently an aposporous growth,
derived from imperfect arrested
sporanges, or even from cells of
the placenta. The archegones
are borne on peculiar structures,
known as archegoniophores^ mas-
sive outgrowths of the prothal-
lium, each archegoniophore bear-
ing either a single arch,egone or
several. The archegoniophore is
usually a multicellular structure,

and the Venters of the archegOttCS
. , ,, , . . ™

are imbedded in US tlSSUC. T.

alatum (Sw.) is habitually apo-

gamous, and is possibly never reproduced sexually. Aposporous pro-
thallia spring in great numbers from all parts of the frond, often quite
independent of the sori, and are more flattened and ribbon-like in struc-
ture than those of most Hymenophyllaceae, They produce large
numbers of stalked gemmae. Archegones have never been observed in
this species, and the antherids are imperfect, and apparently functionless
The spores are multicellular before germination. The archegones differ
from those of other ferns in having a perfectly straight neck.

The sporanges have a complete horizontal or oblique annulus
(incomplete in Loxsoma, R. Br.), and hence dehisce by a vertical fissure.
They are borne on a prolongation of the fertile vein, the columel^ which
projects beyond the margin of the leaf, and is enclosed in the cup-shaped
indusium. The columel or placenta elongates by intercalary growth,,
and the sporanges are produced on it in a spiral line in basifugal succes-

FIG. 61.— Archegoniophore of Trichomanes pyxi-
diferum L., bearing five archegones, art of
different ages (x 175). (After Bower.)

FILICES

sion. In Hymenophyllum (L.) and Trichomanes (Sm.) the sporanges are
sessile and biconvex, and are attached to the columel by one of their
convex faces ; the annulus, projecting in the form of a cushion, separates
the two convexities, and is usually oblique, dividing the circumference
into two unequal portions : in Loxsoma they are pear-shaped and dis-
tinctly stalked. Para-
physes occur only in a
few species of Hymeno-
phyllum. The meso-
phyll of the leaf consists,
in the two larger genera,
of only a single layer of
cells, and the leaves
have hence a filmy and

FIG. 63. — tfymenophyllitin\ spo-
ranges exposed (magnified).

moss -like appearance \
but in Loxsoma there
are several layers of
cells, and the leaf is then
provided with stomates.
The stem is generally
creeping and mostly
very slender, and is pene-
trated by a single axial

FIG. 62. — Hymenophyllum tunbridgense (natural size). 'vaSCUlar' bundle

Many species of Trichomanes are rootless ; and the stem is then densely
clothed with root-hairs, and slender ramifications of the stem assume
the appearance and function of true roots. Even the ordinary branches
of the stem have often been long formed before their leaves emerge from
a rudimentary condition. In some species of Trichomanes the fructifica-
tion is confined to special fertile leaves.

The Hymenophyllaceae include but three genera, of which Loxsoma
comprises a single species only, of creeping habit, native of New

88

VASCULAR CRYPTOGAMS

FIG. 64. — A, germinating spore and prothallium of Hy7neno-
phyllnm ; £, C, Z>, stages in development of prothallium
(x 120). (After Luerssen.)

FIG. 65. — Prothallium of Osutunda
regalis L. a, antherids ; w,
rhizoids; v, growing point. (After
Goebel.)

Zealand ; Hymenophyl-
lum and Trichomanes
nearly 100 species each,
exceedingly delicate and
graceful ferns, growing
mostly on the trunks of
trees and damp rocks,
often within reach of the
spray of waterfalls, in the
moister and warmer parts
of the globe. The smaller
species of Hymenophyl-
lum are known as * filmy
ferns.' The Hymeno-
phyllaceae may be re-
garded as the simplest
and are probably the oldest
family of ferns, and pos-
sibly form a connecting link be-
tween the Muscinese and the Vas-
cular Cryptogams.

LITERATURE.

Mettenius — Ueber die Ftymenophyl-
laceen, 1864.

Janczewski and Rostafinski — (Prothal-
lium) Mem. Soc. Nat. Sc. Cher-
bourg, xix., 1875.

Goebel — (Germination) Ann. Jard. Bot.
Buitenzorg, vii., 1887, p. 57.

Prantl— Untersuchungen zur Morpho-
logic derGefasskryptogamen, Heft I.

Bower — Annals of Botany, vol. i., 1887,
pp. 183 and 269.

ORDER 5.— OSMUNDACE^E.

The prothallium of the Os-
mundaceae is characterised by its
strong tendency to propagate itself
vegetatively, by means of adventi-
tious shoots, and is commonly
dioecious, springing directly from
the spore. It is usually ribbon-
shaped, with a well-defined midrib

FILICES

89

The sessile or shortly stalked, roundish, but unsymmetrical sporanges
are not strictly epidermal in their origin. They bear on one side of their
apex a modified annulus in the form of a group of cells of peculiar form,
and dehisce vertically on the other side. Todea (Willd.) presents no

difference between the fertile
and sterile leaves ; while in
Osmunda (L.)the fructification
has the appearance of a con-
tinuous or interrupted panicle,

FIG. 67. — Mucilage-gland from Osmitnda.
regalis (magnified). (After Gardiner.)

from the entire absorption of
the mesophyll of the fertile
part of the leaf. In some
species of Todea the leaf con-
sists of only a single layer of
cells. In Osmunda there are

FIG. 68. — Sporange of Osiminda
(magnified).

abundant mucilage-cells at
the base of the leaf-stalk.
The ^vascular ' bundles of the
stem are collateral, as con-
trasted with the concentric
bundles of typical ferns, and their course bears more resemblance to
that in Gymnosperms and in Dicotyledons. In the structure of the
leaves, and in the structure and development of the growing point,
Osmundaceae exhibit a transitional condition between the typical ferns

FIG. 66. — Osmunda regalis L. Portion of frond
(natural size).

90 VASCULAR CRYPTOGAMS

and the Marattiacese. The young leaves (in Osmunda cinnamomea, LM
and Todea superba, Col.) present the remarkable peculiarity of their
apex being occupied by a well-marked triangular-conical apical cell.
The family includes only a very small number of species, comprised
in the two genera Osmunda (L.) and Todea
(Willd.). Osmunda regalis (L.), growing in
bogs, with remarkably coriaceous leaves, is
our ' royal fern ' or • flowering fern.'

LITERATURE.

Bower — Proc. Roy. Soc., xxxvii., 1884, p. 42;

and Quart. Journ. Micr. Sc., 1885, p. 75.
Gardiner and Ito — Annals of Botany, vol. i., 1887,

p. 27.

ORDER 6. — SCHIZ^ACE^E.

The ovoid or pear-shaped sessile spo-
ranges are not strictly epidermal in their
origin. The apex of the sporange is occu-
pied by a cap-like zone of cells of peculiar
form, and the dehiscence is vertical. In
the genera Aneimia (Sw.) and Schizaea
(Sm.) the fertile leaves have the paniculate
appearance of an Osmunda. In Schizaea and
Lygodium (Sw.) the sporanges are seated in
two rows on the under side of very narrow
pinnae ; and in Lygodium each sporange is
enclosed in a pocket-shaped industum. In
Aneimia the two lowermost pinnae form a
long-stalked panicle, from which the meso-
phyll has disappeared. In Aneimia and
Lygodium the sporanges spring originally
from the margin of the leaf, but are eventu-
ally placed in the course of development
on its under side. In Mohria (Sw.) they are
placed on the back of the leaf, and are con-
FIG. (^.—LygodhtmpaimatumSvi. cealed by its recurved margin. The differ-

(reduced). ' ,1-1

entiation of tissues, both in the mesophyll

of the leaf and in the ' vascular ' bundles, is very slight. The stem is
in general but feebly developed, and seldom branches ; the leaf-stalk is
penetrated by only a single ' vascular ' bundle. The peculiar position
of the stomates in some species of Aneimia has already been described.

FILICES 91

The family of Schizaeaceae comprises a small number of species, in-
cluded in five genera, of which Mohria(Sw.)and Trochopteris (Gardn.)are
monotypic. Aneimia (Sw.) and Schizaea (Sm.) resemble the Osmundaceae
in their paniculate appearance. All the species of Lygodium (Sw.) pre-
sent the appearance of climbing stems, from the peculiar structure and
mode of growth of the leaves already described. The family is confined
to the warmer parts of the globe.

LITERATURE.

Prantl — Untersuchungen zur Morphologic der Gefasskryptogamen, Heft 2, 1881 ;
also in Engler's Jahrb. 1881, p. 297.

ORDER 7. — MARATTIACE^E.

The Marattiaceae differ more widely from the typical ferns than any
of the families hitherto described, and are by many authorities separated
from them into a distinct class. But the point of divergence most relied
on, the endogenous origin of the sporanges, has lost much of its signifi-
cance since it has been known that the Osmundaceae and Schizaeacese
present connecting links in this respect. The aerial flat prothallium,
the circinate vernation and general structure of the leaf, and the ultimate
structure of the sori, present so many points of contact with the other
orders of Filices, that it seems most desirable at present to retain them
as an aberrant order of the class.

The prothallium, the development of which is very slow, is a dark
green elliptical or heart-shaped plate of tissue, lying on the surface of
the soil, consisting of one or more layers of cells, and with a projecting
hemispherical cushion on the under side. Its development has been
followed out in Marattia (Sm.) and Angiopteris (Hoffm.). Chlorophyll is
formed in the spore as soon as it begins to germinate. The exospore
bursts, and the first cell of the prothallium projects as a papilla between
the two lobes. After a considerable time the first division takes place
at right angles to the direction of growth, and the first rhizoid is formed.
Further divisions follow rapidly, and the prothallium soon becomes a
cellular tissue, and is distinguished from that of typical ferns by its deep
green colour and by its moderately thick cuticle. One of the cells first
formed becomes an apical cell, from which fresh cells are formed until
the prothallium has assumed its ultimate cordate form. The antherids
make their appearance, after a period of some months, on both sides of
the prothallium, but especially on the ventral cushion. Their structure
differs in some respects from that of typical ferns. From a single
superficial cell are produced a central cell, two upper cells, and a
triangular stigmatic cell, which is thrown off. when the antherid is

92 VASCULAR CRYPTOGAMS

mature. Within the central cell are produced from twenty to two hundred
antherozoids, each in its own mother-cell. Both antherids and arche-
gones are deeply sunk in the tissue of the prothallium. The archegones,
only the uppermost part of the neck of which appears above the surface,
are formed on the ventral cushion, very rarely on the upper side of the
prothallium. Their development presents no very special features.

The sporophyte generation has, when mature, the habit and appear-
ance of an ordinary fern. The stem is usually erect and short, with
tuberous base, never attaining a greater height than from one to two
feet ; less often (Kaulfussia, Bl.) a creeping underground rhizome. It
resembles the stem of OphioglossaceSe and Isoeteae in never branching ;
that of true ferns in being densely covered, when erect, with leaves as
well as with roots, so that no portion is left exposed. The growing
point has a single apical cell, and is concealed in a terminal rosette of
large leaves. The fundamental tissue is everywhere traversed by long
rows of tannin-cells ; and lysigenous mucilage-cells
abound in the petioles and in the parenchyme
of the pith and cortex of the stem ; they anasto-
mose freely, and are continuous from the stem
into the roots. The sclerenchyrnatous tissue, so
characteristic of the parenchyme of the stem of
typical ferns, is but feebly developed, or is alto-
gether wanting, in the Marattiaceae. The. ' vascu-

Fro.7o.-Baseofieaf,taikof lar ' bundles are concentric, and resemble those
Marattia cut through. st, of true ferns. A central xylem, composed of wide

stipule ; c, commissure ; v, . . . 1-1 • 111 i

anterior, k, posterior wing scalanform tracheides, is surrounded by the

(natural size). (After Sachs.) ^^ . ^ bundle.sheath js wanting in the

bundles belonging to the stem and leaves, but is present in those of the
root. The bundles bend from the stem into the leaves in the ordinary
way. The stem and rachis of the leaves are not covered with pales, as
in true ferns, nor are they completely glabrous, as in the Ophioglossaceae.
The leaves are thick, coriaceous, and very large, attaining in some
species a length of from five to ten feet. They have a long and very
stout petiole, which is channelled on the upper side ; the lamina unfolds
very slowly, and is either simply or doubly pinnate, less often palmate
or digitate. They are furnished at their base with appendages peculiar
to the Marattiacese among Vascular Cryptogams, the stipules or auricles.
While still in the bud the leaves are rolled up in a circinate manner,
and are entirely enveloped in the large stipules until the lamina unfolds.
The pair of stipules belonging to each petiole form an anterior and a
posterior chamber, separated from one another by a longitudinal wall
termed the commissure. In the posterior chamber is the rolled-up leaf

FILICES 93

to which the stipules belong, the two posterior wings of the stipule
being folded together behind it ; while the chamber formed by the
anterior wings encloses all the younger leaves. The stipules remain
succulent, not merely as long as the leaves last, but even after the
lamina has fallen off; and adventitious buds are not unfrequent upon
them. The leaf-stalk is articulated immediately above the stipule ; the
leaf always becomes detached at this articulation by a smooth scar,
leaving behind the base of the leaf-stalk with its succulent stipules.
The primary and secondary pinnae are attached to their respective rachis
by similar articulations ; and at each articulation is a pulvinus or cushion,
containing collenchymatous tissue. In the mesophyll of the leaf occur,
in all the genera, outgrowths of the cell-walls bounding the intercellular
spaces and projecting into them. Where the intercellular spaces are
small these outgrowths have the form of humps and cones ; in larger
spaces they elongate into long slender filaments which present a super-
• ficial resemblance to the hyphae of Fungi, but are quite solid, and consist
of cuticularised cellulose. They are found also less abundantly in the
leaf-stalk, stem, and root. Layers and bundles of sclerenchyme occur
in the mesophyll, but are only feebly developed and of a light colour.
The leaves of Kaulfussia are characterised by the presence of remarkably
large stomates on the under side, formed in the ordinary way, but dis-
tinguished by the great .size of the orifice, and by the guard-cells forming
a narrow ring, and being surrounded ~by two or three layers of epidermal
cells, which are also arranged in a ring. There are only two semicir-
cular guard-cells, and the structure of these organs is very different from
that of the stomates of Marchantia, to which they bear a superficial
resemblance. Lenticels occur in the leaf-stalk of many species.
Spherocrystals have been found in the mesophyll and leaf-stalk of
Marattia cicutaefolia (Kaulf.) and Angiopteris evecta (Hoffm.).

The roots arise endogenously from immediately beneath the growing
point of the stem. They strike obliquely downwards through the
succulent parenchyme of the stem, penetrating the network of the
' vascular ' bundles, with which they may easily be confounded, and gene-
rally emerging from a leaf-stalk. They are of a lighter colour, greater
thickness, and more delicate texture than those of true ferns, approach-
ing those of Ophioglossaceae. After entering the soil they branch
copiously and apparently monopodially.

The sporanges are produced in large numbers on the under side of
ordinary leaves, each being developed, not from a single cell, but from
a group of cells. They are situated on the veins, and usually form two
rows of sori, which cover the lateral veins either for their whole length
or only near the margin of the leaf ; in Kaulfussia they are placed on

94

VASCULAR CRYPTOGAMS

fine anastomosing branches between the lateral veins. The placenta or
receptacle on which each sorus is seated is a cushion-like outgrowth of
the vein. The sporanges are altogether destitute of an annulus ; the
wall always consists of several layers of cells. In Angiopteris the
sporanges which make up a sorus are quite distinct, ovoid, and sessile,
and dehisce by a vertical fissure on the inner side. In all the other
genera they are more or less confluent, and the entire boat-shaped sorus
is then known as a synange ; but each sporange still dehisces separately
by a vertical slit on its inner side ; or, in Danaea, by an apical pore.
The coalescence is most complete in Kaulfussia, where the circular
sorus has the appearance of a plurilocular basin. The sorus is usually
surrounded by flat lobed hairs of epidermal origin, forming a kind of

FIG. 71. — A, under side of leaf of A n%iopteris caudata ; B, of Marattia ; s. sori ; C, sorus of
Marattia cut through, showing open sporanges. (After Goebel.)

involucre. The true indusium is sometimes altogether wanting. The
sporanges originate from the tissue of the leaf itself. The placenta is
first formed as a cushion-like outgrowth of the fertile vein, partly from
the epiderm, partly from the subjacent tissue. On this originate, in
Angiopteris, the separate sporanges as papillae, each composed of a
number of cells. In Marattia, however, while the two rows of sporanges
are distinct, those of each row are confluent from the first, but each has
its own archespore. The primary mother-cells of the spores are formed
at an early period within the archespore.

The spores are formed in fours within their parent-cells, and resemble
in general character those of typical ferns. Two different forms of spore
sometimes occur in the same species, but they present no difference on

FILICES 95

germination. The wall of the spore is composed of three layers ; the
surface is covered by minute wart-like spines.

Vegetative propagation takes place with great facility in some species
of this family. In Marattia cicutaefolia the leaves, or even the stipules,
have only to be cut into small pieces, and placed in damp soil or in a
bottle, when a number of adventitious buds will be developed in con-
nection with the * vascular ' bundles.

The Marattiaceae comprise only a very small number of species,
almost entirely confined to the tropics, and included in the four genera
Angiopteris (Hoffm.), Marattia (Sm.), Danaea (Sw.), and Kaulfussia(BL).
With the exception of the stipules, and the great thickness of the leaves,
they have quite the habit of ordinary ferns.

LITERATURE.

De Vriese and Harting — Monographic des Marattiacees, 1853.

Mettenius — Ueber den Bau von Angiopteris, 1863.

Luerssen — Mittheil. aus denvGesammtgebiete der Bot., vol. i., Heft 3, 1872; and

Bot. Zeit., 1872, p. 768 ; and 1873, pp. 624 and 641.
Russow — Vergleichende Untersuchungen, 1872, p. 185.
Holle— Bot. Zeit., 1875, P- 2I5-

Jonkman — Bot. Zeit., 1878, p. 129; and Archives Neerland., 1880.
Schenk— Ber. Deutsch. Bot. Gesell., 1886, p. 86.

Class V.— Ophioglossaceae.

This small but very well-defined group, although popularly included
with the Filices under the common denomination of ferns, differs from
them in several important points of structure, in some of which a con-
necting link is furnished by the Marattiaceae. The prothallium is under-
ground and destitute of chlorophyll, exhibiting a similarity to that of
Lycopodiaceae rather than to that of true ferns. The stem rarely at-,
tains more than a few inches in height, and usually does not branch ; it
is remarkable for its slowness in growth. It contains no sclerenchy-
matous layers. The leaves are not circinate in vernation, and the
petiole is furnished at the base with lateral outgrowths, which have
been compared to the stipules of Marattiaceae. The venation is dicho-
tomous or reticulate, and generally inconspicuous. The sporanges are
completely endogenous in their origin, and are never borne on the under
side of the green leaf, but on a separate branch of the leaf, altogether
destitute of green parenchyme, and form a compound ' fructification,'
. resembling in appearance a spike or panicle : there is no annulus. The

96

VASCULAR CRYPTOGAMS

1 vascular ' bundles of the stem are collateral ; the primitive elements of
the xylem are usually scalariform tracheides.

The oophyte generation has been observed in only a few species. In

FIG. T2.—Opkioglossum vulgatum L. A, p'ant (natural size) ; B, portion of
sporophyll (magnified).

Ophioglossum (pedunculosum, Desv.) it has at first the form of a small
round parenchymatous tuber, entirely buried in the soil and destitute
of chlorophyll, from which is subsequently developed a cylindrical
vermiform shoot, which grows erect by means of a single apical cell,

OPHIOGLOSSA CE.^

97

and very rarely branches, and then but slightly. The apex of this shoot
finally appears above ground, develops chlorophyll, becomes lobed, and
ceases to grow. When fully developed, the prothallium consists of an
axial bundle of elongated cells surrounded by shorter
parenchymatous cells : its upper surface is clothed with
rhizoids. Its length sometimes amounts to as much
as two inches, though generally it is much shorter ; its
breadth is always very small. In Botrychium (Lunaria,
Sw.) the prothallium is a minute light brown or yel-
lowish white ovoid mass of firm cellular tissue, subter-
ranean and destitute of chlorophyll, and producing
rhizoids from all sides. In both genera the prothallium
is monoecious.

The archegones^ antherids, and antherozoids do not
differ materially in structure from those of Filices.

i

FIG. 74.— Longitudinal section of prothallium of Botrychium Lunaria^
showing archegones and antherids (x 50). (After Hofmeister.j

Neither archegones nor antherids are limited in their
production to any particular part of the prothallium.
In Botrychium (Sw.) the antherids are cavities in the
tissue chiefly of the upper side of the prothallium, and
the archegones are produced in their immediate
vicinity; in Ophioglossum (L.) they project slightly above
the surface. Before opening to discharge the anthero-
zoids, they are covered by a few epidermal layers of
cells. The mode of formation of the antherozoids
resembles that of Marattiaceae. Their mother-cells
originate from repeated divisions of one or two cells of

..-rycm the inner tissue ^g beneath these \*y^ They are
£%SaHa Sw' (nat- comparatively large, and escape through a narrow open-
ing in the layers of cells which originally covered the
antherid. The archegone consists of a venter containing the central
cell, and a neck composed of four vertical rows, each consisting of two
or more cells, and only slightly projecting above the surface. The

H

98 VASCULAR CRYPTOGAMS

venter is completely imbedded in the prothallium, its wall being de-
veloped out of the tissue of the latter.

The course of development of the embryo and rudimentary sporo
phyte has not yet been followed out in a sufficient number of instances
to warrant a general description ; in those in which it has at present been
observed it appears to present some discrepancies.

The short stem is erect and entirely glabrous, often with a swollen
tuberous base ; only in Helminthostachys (Kaulf.) is there a creeping
underground rhizome. In only a very few exceptional cases does it
branch. The flattened apex of the stem consists of an irregular meristem
derived from a single pyramidal apical cell. The fundamental tissue of
the stem consists of short nearly cylindrical thin-walled succulent cells,
which are longer in the leaf- stalk, interspersed with large intercellular spaces.
It exhibits a striking difference from the corresponding tissue of true ferns
in the entire absence of sclerenchymatous layers. It is separated by the
1 vascular ' cylinder into a cortical and a medullary parenchyme. It has an
epiderm well provided with stomates, and exhibits sometimes a remarkable
development of layers of cork. The ' vascular ' bundles form (in Ophio-
glossum vulgatum, L.) a hollow cylindrical network, from each rnesh of
which is sent out a leaf-trace. The whole of the tissue which fills up
the meshes is frequently transformed into scalariform tracheides, so that
considerable lengths of the stem then contain a continuous hollow
cylinder of lignified tissue. The bundles of the stem are collateral, the
xylem occupying the axial, the phloem the peripheral side ; and the
structure is the same in Botrychium (Lunaria). Those of the leaf-stalk
are four to eight in number, arranged in a circle and separated by fun-
damental tissue. In Ophioglossum they are collateral, the axial portion
consisting of narrow reticulate tracheides, the peripheral portion of a
broad band of phloem, containing sieve-tubes ; while in Botrychium
they are concentric, consisting of a broad band of scalariform or reticulate
tracheides surrounded by a thick layer of phloem. There is no bundle-
sheath in Ophioglossum, and only a rudimentary one in Botrychium.

The roots of Ophioglossaceae are remarkable from the slight develop-
ment of the root-cap, and the absence of root-hairs. They spring from
the short stem in the midst of the leaf-insertions, and rarely branch, then
always monopodially. Like the stem, they originate from a single
pyramidal apical cell. The roots of Ophioglossum give rise to adven-
titious buds.

The leaves are always very few in number, often only one on each
stem, and the number is uniform in the same species. They are re-
markable for the slowness of their growth, which extends, in Botrychium
Lunaria, over five years, the leaf only rising above the surface of the

OPHIOGLOSSACEJ:

99

soil at the commencement of the fifth year ; where there are several
leaves, the points of origin of those of successive years have a spiral
phyllotaxis. They are quite simple and entire, simply pinnate, or twice
or thrice pinnate. There is always a long petiole, which is furnished
with a ligular or sheath-like outgrowth on each side ; and the coalescence
of these appendages forms a hollow chamber within which the leaf is
developed, similarly to what takes place in Marattiaceae. They are
never circinate in vernation. They are of coriaceous texture, and are
always quite glabrous, and possess a well-defined epiderm furnished
with stomates on both surfaces, and in immediate contact with the
mesophyll, without any intermediate hypodermal layers. The mesophyll
is large-celled and spongy, with large intercellular
spaces. The 'vascular' bundles are but feebly deve-
loped ; they anastomose in Ophioglossum, but only
dichotomise in Botrychium and Helminthostachys.
In most species all the leaves are fertile ; but in Rhi-

FlG.

76. — Ophioglos-
sum vulgatum. Por-
tion of sporophyll
with closed spo-
ranges, s ; g; ' vas-
cular ' bundle ( x 10).

FIG. 75.— Botrychium Lunarict. Portion of sporophyll with
open sporanges (magnified). (After Luerssen.)

zoglossum (Presl) (a section of Ophioglossum) there
are both barren and fertile leaves. The leaf divides
at an early period into two branches — an outer branch
which is sterile, and which alone develops chlorophyl-
lous parenchyma; and an inner fertile branch, the sporo-
phyll, which springs either from the base or middle of
the lamina or from the leaf-stalk. This branch never
has any green parenchyme except in Helmintho-
stachys.

The sporanges resemble in their origin and mode of formation those
of Marattiaceae. They are not formed from a single cell, but from a
group of cells in the substance of the sporophyll which are differentiated
from the surrounding tissue. The terminal cell of the axial row beneath
the epiderm is the archespore from which all the spores are formed ; it
is surrounded by the layers of mantle-cells constituting the tapete,
which are formed out of the epidermal cell immediately above the
archespore, and which ultimately disappear. The wall of the sporange,
consisting of several layers of cells, is developed from the epiderm, and
contains stomates. Strasburger regards each sporange as corresponding
homologically to an entire sorus in the Filices— being, in fact, a meta-

H 2

ido VASCULAR CRYPTOGAMS

morphosed portion of a leaf. They are buried, in an early stage, in
parenchyme, which ultimately becomes entirely absorbed, and which is
traversed by ' vascular ' bundles anastomosing into long meshes. The
sporanges require an entire year for their complete development. They
have no annulus, and dehisce vertically from unequal tension of the
epidermal and hypodermal layers of cells. In the formation of the
spores each mother-cell divides into four ' special mother-cells,' with
very thin cell-walls ; the protoplasm in each of these becomes invested
with a new and firmer cell-wall, and the spores are thus completely
formed, and are ultimately set free by the absorption of the walls both
of the special mother-cells and of the original spore-mother-cells. The
spores are nearly cubical ; the exospore is strongly cuticularised, and is
furnished with prominent knobs and ridge.

Vegetative propagation is known to take place only by means of
adventitious buds produced on the roots.

The Ophioglossaceae include only a very small number of species,
comprised in the genera Ophioglossum (L.), Botrychium (Sw.), and
Helminthostachys (Kaulf.), spread over the whole globe. They are small
plants, dying down each year, only a few species attaining the height of
more than a foot, with a single or only a very few coriaceous leaves, and
a conspicuous ' fructification,' which is simple and spicate in Ophio-
glossum and Helminthostachys, branched and paniculate in Botrychium.
They are of no known economic value. They are represented in our
English flora by the * adder's-tongue ' (Ophioglossum vulgatum, L.) and
' moonwort ' (Botrychium Lunaria, Sw.).

LITERATURE.

Mettenius — Filices Hort. Bot. Lipsiensis, 1856.
Hofmeister — Abhandl. Sachs. Gesell. Wissenschaften, 1857.
Holle— Bot. Zeit, 1875, pp. 241 et seq.

Prantl— Ber. Deutsch. Bot. Gesell., 1883, pp. 155 and 348 ; and Jahrb. Bot. Gart.
Berlin, 1884.

Class VI.— Equisetacese.

The Equisetacese or Horsetails are a very small group of plants, con-
sisting only of a small number of species, arranged in a single genus,
of remarkably uniform and peculiar habit. The aerial stems, which are
invariably erect or ascending, arise from a creeping underground rhizome,
and are characterised by their perfect multilateral symmetry and verticil-
late branching. The ascending stem is always elongated and slender,
fluted with longitudinal furrows and ridges, and is remarkable for the

EQUISETACE^E

101

FIG. 77. — Equisetum sylvaticiim L. a, non-chlorophyllous fertile branch : b, chlorophyllous
fertile branch ; c, barren branch (reduced).

102 VASCULAR CRYPTOGAMS

tendency displayed by the epidermal cells to deposit silica in their cell-
walls. It is always divided into very distinct nodes and internodes, and
is furnished at the nodes with modified foliar organs of a membranous
character, the leaf -sheaths, the margin of which is split into a number of
teeth. The tissue of the internodes is permeated by large intercellular air-
canals. At the nodes the stem (except in some species the fertile stem)
gives out a whorl of symmetrically arranged branches, which almost
precisely resemble the main stem except in their smaller size and simpler
structure, consisting of internodes and nodes furnished with leaf-sheaths ;
but these secondary branches do not usually again branch. The stem and
root increase in length by means of a single large pyramidal apical cell,
which produces three rows of segments. The ' vascular ' bundles of the
stem are but feebly developed, and contain but little xylem. Both stem
and branches perform the function of leaves, contain chlorophyll, and
are provided with stomates.. The sporanges are never borne on the
branches or leaves, but are collected into spicate or catkin-like ' fructifi-
cations,' borne at the extremity either of ordinary vegetative steins, or of
special fertile stems which resemble the ordinary stems in structure, but
contain no chlorophyll and do not branch. The sporanges spring from
the inner side of the peltate scales of which these ' fructifications ' are
composed ; they dehisce by a longitudinal fissure, but have no annulus
like those of ferns. The spores are distinguished from those of all other
Vascular Cryptogams by being enclosed in four distinct coats, 4he outer-
most of which ultimately breaks up into four ribbon-shaped strips, and
detaches itself from the spore except at the point of junction of these
strips, which are termed elaters. The elaters are remarkably hygroscopic,
absorbing or giving off water with every change in the moisture of the sur-
rounding atmosphere. In consequence of this they are constantly altering
their shape, and imparting a somewhat rapid motion to the spores, thus
assisting in their dissemination. On germinating the spore gives rise
to a strap-shaped prothallium, which has an independent power of
growth, and is usually dioecious. The antherids and archegones differ in
no essential point from those of other Vascular Cryptogams. Male and
female prothallia are generally produced in close proximity to one
another, so that impregnation is readily effected through the agency of
moisture.

The oophyte generation of Equisetum (L.) springs directly from the
spore, which contains chlorophyll. On germinating the spore throws off
its outer coats, and changes its form from spherical to pear-shaped. The
contents, still clothed in the thin endospore, then divide by a wall, the
direction of which is not constant, into two cells of unequal size ; accord-
ing to Stahl the direction of this division depends on the direction of the
rays of light. From the smaller of these two cells the chlorophyll

EQUISETACEJE

103

rapidly disappears entirely ; it undergoes no further division, but elongates
rapidly into a long hyaline rhizoid. The larger of the two primary cells,
which still contains abundance of chlorophyll, divides further by walls, at
first in two directions only, into a multicellular plate which increases
rapidly by apical growth, and soon branches in one plane. A difference
is now set up between the develop-
ment of the male and female pro-
thallia. The former remain com-
paratively small and narrow, and
the cell-division continues in the

FIG. 78. — A. male prothallium of Equisetum
arvense L. ; a, antherids ( x 200). (After Hof-
meister.) B — E, antherozoids of E. maximum
Lam. in different stages of development
( x 1200). (After Schacht.)

two directions only ; they consist,
therefore, permanently of only a
single layer of cells, and display
but little lobing. Their colour is
yellowish green. The female pro-
thallia, on the other hand, grow to

a considerably larger size, as much as half an inch in length, are of a
deeper green colour, and at an early period form a number of lobes at
their anterior portion, which consist of masses of merismatic tissue, cell-
division taking place in the tangential as well as the other two directions ;
they branch also in the same plane much more abundantly than the male
prothallia. The formation of female or male prothallia appears to depend

FIG. 79. — Vertical section of lobe of female pro-
thallium of E, arz'ense. a, archegones; h,
rhizoids ( x 600). (After Goebel.)

104

VASCULAR CRYPTOGAMS

ar

on the greater or less supply of nutriment. The antherids make their
appearance about five weeks after germination, the archegones not till
much later.

The antherids arise at the extremity or margin of the male prothallia.
They are first separated off as papillae by a tangential wall ; further
divisions then arise, by which they are divided into a large central cell
and a single layer of much smaller peripheral 'mantle-cells.' The
contents of the central cell then divide into the mother-cells of the
antherozoids. These escape, still enclosed in the delicate wall of the
' special mother-cell,' by the separation from one another, through the
action of water, of the apical cells of the mantle-layer ; the expulsion often

takes place with considerable force,
and is due to the swelling up of the
walls of the mother-cells; sometimes
they emerge still all united together
into a ball. The antherozoids are
much more numerous than in ferns ;
probably several hundreds are formed
in each antherid ; they are also
much larger, being the largest in any
class of Cryptogams. Each anthero-
zoid (see fig. 78) is a thread of pro-
toplasm, gradually narrowing from
the posterior to the anterior end,
where it is coiled spirally, and bears a
tuft of very long delicate vibratile
cilia. The posterior portion is
widened into a thin membranous
fin-like expansion, by the undula-
tions of which its motion through the water is greatly assisted, and may
continue for many hours. To the posterior portion of the antherozoid
is also frequently attached for a time a minute bladder containing
starch, which is regarded by some as the wall of the special mother-cell,
by others as a vesicle contained in it. The body of the antherozoid
appears to be formed from the nucleus of the mother-cell, its cilia from
the cell -protoplasm.

The archegones are formed on the under (shaded) side of the thick
lobed portions of the female prothallia, a lobe being usually situated
immediately beneath an archegone, and assisting in its impregnation by
retaining water. By the continued growth of the subjacent tissue they
are ultimately pushed on to the upper surface, and hence the direction
of growth of the archegone is the opposite of that of ferns. Otherwise

FIG. 80.— Portion of female prothallium of E.
sylvaticum, with projecting archegone, ar.
(After Buchtien, greatly magnified.)

EQUISETACEsE 105

the mode of development and structure of the archegones of Equisetum
differ in no essential respect from those of other Vascular Cryptogams.
The basal cell is wanting, and the neck-canal-cell does not extend the
whole length of the neck. The lower portion of the neck and the venter
remain completely imbedded in the tissue of the prothallium, while the
outermost or stigmatic cells of the neck lengthen greatly, and ultimately
bend outwards, giving to the archegone, when ready for impregnation,
the appearance of a miniature four-armed anchor.

Although the prothallium of Equisetum is normally dioecious, it
is not very uncommon to find a few archegones on male, and a few
antherids on female prothallia. The abnormal sexual organs then
generally make their appearance later than the normal ones.

The mode of formation of the embryo from the impregnated oosperm
is essentially the same as in other classes of Vascular Cryptogams. The
first division-wall is vertical to the axis of the archegone, and therefore
parallel to the surface of the prothallium ; by subsequent walls a division
takes place into octants. Of the four quadrants of the upper half, one
gives birth to the rudimentary stem, with a triangular pyramidal apical
cell, while from the three others proceed two cotyledons, which at a very
early period unite in their growth with the first leaf which proceeds from
the apex of the stem. From the lower quadrants of the octant are
formed \hefoot and the first root. The first few stems of the sporophyte
generation are successively thicker, and with a larger number of teeth
in their leaf-sheaths, until ultimately mature stems are produced from
perennial underground rhizomes.

The stem of Equisetum always consists of very distinct more or less
elongated internodes, which are hollow, but are closed above and below
at the nodes by transverse septa or diaphragms. The cortex of each
internode is continued upwards above its upper node into a leaf-sheath,
which embraces the base of the next internode above, and is split at its
margin into teeth, varying from three or four to a considerable number.
From each tooth of the leaf-sheath a ' vascular ' bundle descends verti-
cally as far as the next node. The teeth at each node always alternate
in position with those of the leaf-sheaths belonging to the nodes next
above and next below it, and each descending bundle branches at the
node into two short diverging arms, each with its own xylem and phloem,
by means of which it unites with the two adjacent bundles of the next
internode below, where they descend into it from the sheath-teeth in
which they originate. In addition to the large central cavity in the axis
of each internode, the cortical tissue contains a number of much smaller
cavities running vertically through the internode, the lacunce or valle-
cular canals, which alternate with the * vascular ' bundles, and are there-

io6

VASCULAR CRYPTOGAMS

fore intermediate between the sheath-teeth ; these canals are of lysi-
genous origin — that is, they result from the disappearance of masses of
cells. Each bundle also contains a longitudinal air-cavity, or carinal

canal (sometimes called the ' essential air-
cavity '). The outline of the stem always
shows a number of alternate ridges and
furrows ; the ridges correspond to (or
are on the same radii as) the ' vascular '
bundles, the furrows to the cortical lacunae.
This general description applies equally to
the primary vegetative stems, the fertile
unbranched stems, and the underground
rhizomes ; the branches of the barren
stems have no axial cavity or cortical
lacunas. In those species where the fer-
tile differ in structure from the barren
shoots, this appears to result from an
arrest of development of the latter. The
difference consists essentially in the
absence of chlorophyll, the suppression
of branching, and the absence of sto-
mates, as well as in the greater develop-
ment of the leaf-sheaths. It is ^possible
to induce artificially the fertile shoots of
E. arvense (L.) to put out green branches
from the lower internodes, chlorophyll
being also formed in the main stem.

The branches always spring from
within the leaf-sheath at its base, each
branch in the space between two teeth ;
they therefore correspond in number to
the * vascular ' bundles of the stem, and '
are always arranged in a whorl. The same
description applies to the roots. The
number of leaf-teeth and bundles is always
smaller on the secondary than on the pri-
mary axes, and these, as a rule, do not
again produce branches. In some species
even the primary stem never branches.
The whorl in which the branches stand is, however, not a true, but a
false whorl — that is, the phyllotaxis originally shows a regular spiral
one-third divergence ; but by subsequent unequal growth the insertions

FIG. 81. — E. maximum. A, portion of
stem (natural size). 2, i1, internodes ;
h, central cavity ; /, cortical lacunae ;
S, leaf-sheath ; a, a.', a", branches.
B, longitudinal section of rhizome
( x 2). K, transverse diaphragm ; ft, /t,
cavities ; £-, ' vascular ' bundle ; /,
cortical lacunae ; S, leaf-sheath. C,
transverse section of rhizome. D,
union of ' vascular ' bundles of two in-
ternodes, i, i • K, node. (B — 1),
diagrammatic.)

EQUISETACE& 107

come ultimately to stand on a level. On the rhizomes the ridges and
furrows of the outer surface are generally less well marked, and the axial
cavity of the internode is sometimes wanting ; but the vallecular and
carinal canals are always present, and play an important part in the
diffusion of air through the tissue. The aerial stems, both barren and
fertile, are usually completely formed in miniature during the preceding
year within the underground bud, and their rapid growth after they
appear above the soil is mainly due to the great elongation of the
internodal cells. The ascending stem and all other aerial parts of the
plant are always entirely destitute of hairs ; while the rhizomes and the
underground leaf-sheaths are frequently covered with a felt of root-
hairs.

The firmness and strength of the slender aerial stem are not due, as
in ferns, to the ' vascular ' bundles, but mainly to the siliceous epiderm
and the firm hypodermal tissue. The epiderm, consisting of a single
layer of elongated cells, is provided with stomates in the green, leafy,
aerial stem, but not usually in the colourless fertile stem, or in the
rhizomes. In most species of Equisetum the stomates lie in one or
more longitudinal rows in the furrows of the stem only ; but in
E. arvense, according to Miss E. A. Southworth ('American Naturalist,'
1884, p. 1041), also on the ridges. Stomates also occur on the leaf-
sheaths. The stomates either have their orifice on a level with the
surface (Equiseta phaneropord) or considerably depressed below it
(Equiseta cryptopora) ; in the latter case they frequently do not open
directly into the surrounding air, but are situated in the hypodermal
tissue, beneath a ' false stomate,' or pore in the epiderm. The stomates
(fig. 82) differ from those of other classes of vascular plants in being
formed of two pairs instead of a single pair of guard-cells. Strasburger
(Beitr. zur Entwickelungsgesch. der Spaltoffnungen, in Pringsheim's
Jahrb., vol. v., p. 297) terms the lower pair ' subsidiary cells ' of the
true stomate. All the cells of the epiderm, even the guard-cells of the
stomates, have their outer walls or cuticle strongly silicified ; and these
deposits of silica frequently project above the surface in the form of
fine granules, bosses, rosettes, rings, transverse bands, teeth, or spines.
On the guard-cells they usually have the form of ridges radiating from
the orifice. Beneath the epiderm, except on the deciduous fertile stems,
bundles or layers of firm thick-walled cells generally constitute a
sclerenchymatous hypodermal tissue, which is especially developed in
the elevated ridges of the aerial internodes. On the underground stems
both epiderm and hypoderm frequently assume a beautiful brown-red
colour. In addition to silica, analysis of the ash of Equisetacese
(Dieulafait, ' Compt. Rend.,' vol. c., 1885, p. 284) shows the presence

io8

VASCULAR CRYPTOGAMS

of a large amount of sulphates, and the total absence of alkaline carbon-
ates.

A large portion of the parenchymatous fundamental tissue is desti-
tute of chlorophyll ; it is only in the vegetative aerial shoots that there
is any considerable development of chlorophyllous tissue, and then it is
usually situated in the furrows beneath the stomates. The ' vascular '
bundles of Equisetum are collateral, and are much less strongly lignified
than those of ferns. They lie in a circle between the medulla and the
cortex, between and somewhat within the cortical canals, and necessarily
run parallel to one another. As will be seen from the description given
above, each bundle is the result of the coalescence of two branches, one
of which originates in the leaf-sheath, while the other develops in the

FIG. 82. — Stomate of E. hyemale'L. (x 390). A. front view ; B, transverse section of stem, showing
side view ; C, siliceous residuum after maceration. (After de Bary.)

internode itself, from above downwards. At the angle where the two
arms meet, the formation of tracheides begins in each ; the lower end
of each bundle unites by two lateral branches with the two next bundles,
one on each side, of the next lower internode ; and the bundles are
therefore of the description known as 'common.' Their course re-
sembles more that of the bundles of most Dicotyledons and Conifers
than that of ferns. Each bundle is traversed longitudinally on its axial
side by a carinal canal, occupying the place of the first tracheides,
which have become absorbed ; right and left of this, in the mature
bundle, are reticulate, annular, and scalariform tracheides ; on the
outside is the phloem-portion of the bundle, consisting of a few wide

EQUISETACE^E 109

sieve-tubes and narrow cambiform cells. In most species (e.g. E. ar-
vense) a general bundle-sheath, or plerome-sheath, consisting of a single
layer of cells, encloses the entire circle of bundles, as in most Flowering
Plants ; while in others (E. limosum, L., and littorale, Kuhlw.) each
individual bundle is enclosed in a separate special bundle-sheath, as in
ferns. In the colourless fertile shoots they bend out into the pedicels of
the peltate scales of the ' fructification,' as they do into the leaf-sheaths.

The growth of the stem takes place through the activity of a single
large pyramidal apical cell with an inverted triangular base. There is
no other group of plants which exhibits such a well-defined single apical
cell or exclusively apical growth. Normally the terminal bud never
branches, branching taking place solely by lateral buds produced at
the nodes. It was formerly thought that the Equisetacese display the
only known example of lateral branching being due to the formation of
endogenous buds ; but recent researches have shown (in E. arvense)
that these lateral bud<? are not of endogenous origin, but originate from
a single superficial cell of the growing point of the stem in the ordinary
way. The segments resulting from the first divisions of the apical cell
lie in three straight rows, and are arranged in a spiral divergence of one-
third.

The roots are produced in whorls at the nodes of the underground
stem, in direct connection with lateral buds, or, under favourable con-
ditions, at the nodes of the aerial stems. They are furnished with a
root-cap, increase by the segmentation of a single apical cell, and are
penetrated by an axial ' vascular ' bundle surrounded by a large air-
cavity formed by the coalescence of intercellular spaces owing to the
absorption of intermediate cells. The weak bundle, in which the
tracheides are but feebly developed, is concentric, with the xylem in the
centre. The secondary or lateral roots, which arise in acropetal succes-
sion on the primary root, differ in their origin from those of ferns and
other Vascular Cryptogams. In these latter it is the innermost layer of
cells belonging to the fundamental cortical tissue immediately surround-
ing the axial 'vascular' bundle that becomes differentiated into the
bundle-sheath or endodermal layer, within which lies the pericambium
of the bundle itself ; and the lateral roots originate from the innermost
layer of the cortex separated by the pericambium from the bundle. In
the roots of Equisetacese the pericambium is wanting, and its place is
to a certain extent supplied by the innermost cortical layer, from which
the lateral roots spring, and therefore in close contact with the periphery
of the axial bundle. The bundle-sheath itself is, in the Equisetaceae,
formed from the row of cortical cells next to the innermost row, and not
from the innermost row itself, as in other Vascular Cryptogams.

110

VASCULAR CRYPTOGAMS

The sporanges of the Equisetaceae are collected into terminal spicute
' fructifications ' of a cone-like or catkin-like character, resembling
nothing else among existing. Vascular Cryptogams. These are borne at
the extremity either of the ordinary green vegetative stems, whether
branched (E. palustre, L.) or unbranched (E. hyemale, L.), or of special
fertile stems (E. arvense, pratense, Ehrh., maximum, Lam.), which are

then always simple, even when the
barren stems are branched, and are
usually stouter, nearly or quite desti-
tute of chlorophyll, and with much
larger leaf-sheaths and coarser teeth.
As already mentioned, these can be
artificially converted into vegetative
stems ; and occasionally deciduous
fructifications are borne at the extre-
mity of the ordinary green branched
stems, in species which normally pro-
duce special fertile stems (E. arvense).
The sporanges are not, like those of
typical Filices, trichomic or epidermal
in their origin ; their development
closely resembles that in the Marat-
tiacese. They are endogenous out-
growths of peculiarly metamorphosed
leaves, the peltate scales or sporophylh,
arranged, like the branches, in whorls.
Intermediate between these and the
uppermost whorl of ordinary leaf-
sheaths there is (in E. maximum) a
whorl of barren but more or less
modified leaf-sheaths, forming a small
annular girdle, the involucre or an-
nulus. The whorls of sporangiferous
scales, of which a number are formed
above this involucre, make their first
appearance as similar annular girdles,
projecting but slightly from the stem, but gradually forming a hemi-
spherical cushion. This cushion finally breaks up into a number of
plates, the surface of which is parallel to that of the stem ; and these, by
mutual pressure, become polygonal and usually hexagonal ; each plate
or disc is attached to the stem by a slender pedicel at right angles both
to its surface and to that of the stem. On the inner surface of these

FlG. 83. — A, upper part of ferule stem of E.
maximum (natural size) ; b, leaf-sheath ;
a, annulus ; x, sporophylls and their
stalks. B, sporophylls ( x 6) ; sg~, spo-
ranges. (After Goebel.)

EQUISETACE^E in

discs are developed the sporanges, from five to ten on each disc,
arising at first as small multicellular projections. The archespore is the
terminal cell of a hypodermal row on the under side of the sporophyll,
the sporogenous tissue resulting from its division. The mantle-cells are
formed in the same way as in Ophioglossaceae, but are not so sharply
defined. The mother-cells of the spores are connected together in
groups of fours or eights, and float freely in the fluid which fills the spo-
range. The mode of formation of the spores affords an exceedingly
good illustration of the production, by free-cell-formation, of new cells
within a mother-cell. When division is about to take place, the proto-
plasm first becomes perfectly clear, the nucleus disappears, and a
number of granules arrange themselves in the form of a disc. The
protoplasm then again becomes turbid, with the exception of two clear
spots, one on each side of the disc, which are the rudiments of the
fresh nuclei. These, however, after a time again disappear, and their
place is taken by four smaller nuclei, each of which is surrounded by
a number of the granules which formed a portion of the original disc.
Round these nuclei the cell-protoplasm begins now to collect into four
separate masses, which gradually become globular ; and these are the
special mother-cells of the spores after each has become invested with
a very delicate coat of cellulose. This process, which has a remarkable
analogy to the formation of the pollen in Flowering Plants, especially in
Conifene, does not vary in any essential point from that in the other
orders of Vascular Cryptogams ; but it has been followed out with the
greatest minuteness and success in Equisetum (limosum, L.).

The mature sporange dehisces by a longitudinal fissure on its inner
side facing the sporophyll. The mechanism of the bursting is similar
to that of the anther of Flowering Plants, and results from the unequal
contraction of lignified and of non-lignified portions of the wall, which
is furnished with annular or spiral thickenings to its cell-walls. The
various coats of the spores are formed while still within the mother-cell.
The first formed is the outermost, a non-cuticularised coat capable of
swelling, which becomes gradually detached, and finally splits into two
bands, the elaters, which remain attached to the spore only at one point,
in the centre of each, where they meet, while the distal ends of each are
dilated into a flattened spathulate form. When the spore escapes from
the sporange the four elaters are stretched out nearly straight ; when
moistened they roll up, owing to their unequal lignification, covering up
the spore almost entirely, as they did at first before becoming detached.
The second coat is more or less cuticularised, and on germination also
raises itself in folds from the innermost coat, which is closely applied to
the contents of the spore, and is again differentiated into an outer

112

VASCULAR CRYPTOGAMS

granular cuticularised exospore, and an inner endospore, composed of
unchanged cellulose. So strong is the hygroscopic property of the
elaters, that, even if lightly breathed on, the spores of Equisetum are
seen under the microscope to be in active motion, from constant changes
in the humidity of the air. The spores contain chlorophyll, and, in
consequence, retain their vitality only for a very few days, and germinate
in a few hours after being placed in favourable conditions. In this
respect they show a striking contrast to those of ferns.

FIG. 84. — Stages in the development of spore of E.
limosum ( x 800). i and e, outer coat from which the
elaters are formed ; 2, 3, inner coats. (After Gcebel.)

FIG. 85. — Spore with elaters extended (magnified).

FIG. B6.—E. limosum L.
Rhizome and tubers.

The only mode of vegetative propagation known in the Equisetaceag
is by the production of tubers on the rhizomes and on the underground
portions of the erect stems ; they are peculiarly modified internodes, filled
with starch and other food-materials, and may remain dormant for years.
The buds, especially those produced at the lower nodes of the erect
stem, also have the power of retaining their vitality for a considerable
pericd in a rudimentary condition ; and, when they vegetate, develop into
branches of great vigour. Tomaschek (' Oesterr. Bot. Zeitschr.,' 1881,
p. 245) induced prothallia of Equisetum to hibernate by growing them

EQUISETACE.E 113

in a warm situation, in which condition they attained a large amount of
independence, and propagated freely by budding.

The number of known species of Equisetum, commonly known as
' horsetails,' does not exceed 20 or 25 ; they are most numerous in the
temperate regions, decreasing in number both towards the pole and the
equator, and are very rare in the Southern Hemisphere. The stem is
always very slender, and seldom exceeds two or three feet in height,
though E. giganteum (L.) reache/ 20 to 40 feet in the tropics, with a
climbing habit. Most of the species prefer loose sandy or gravelly soil
in damp situations ; several grow in marshes or standing water. The
erect stems are mostly annual, but in a few species they endure for
several years ; while the rhizome is always perennial, and frequently
attains great size both in depth and in lateral extension. The species
are all remarkably similar in habit, differing chiefly in the presence or
absence of special fertile stems, the position of the stomates, and the
degree of branching ; but the classification of the species into two dis-
tinct groups of ' homophyadic ' and 'heterophyadic ' is not a natural one.
Each species is also characterised by a special arrangement of the
1 vascular ' bundles, and of the air-cavities as seen in a transverse section
of the stem. In external form, but not in internal structure, they call
to mind Ephedra among Gymnosperms, and Casuarina among Angio-
sperms. The large amount of silex deposited in the epiderm renders
several species, especially E. hyemale, useful for scouring purposes, and
they are popularly known under the name of ' Dutch rushes.'

LITERATURE.

Cramer — in Nageli u. Cramer's Pflanzenphys. Unters., vol. iii., 1855.

Sanio— (Epiderm and Stomates) Linnsea, 1857-8, p. 385.

Duval-Jouve — Hist. Nat. des Equisetum, 1864.

Rees — (Apex of stem) Pringsheim's Jahrb. wiss. Bot., 1867, p. 209.

Milde — Monographia Equisetorum, 1867.

Pfitzer— (Bundle-sheath) Pringsheim's Jahrb. wiss. Bot., 1867, p. 297.

Famintzin — (Buds) Bull. Acad. Sc. St. Petersburg, vol. ix., 1876.

Campbell— (Pro thallium) Amer. Natural., 1883, p. 10.

Leclerc du Sablon — (Sporange) Bull.. Soc. Bot. France, 1884, p. 292; and Ann.

Sc. Nat. (Bot.), vol. ii., 1885, p. 5.

Goebel— (Fertile shoots) Ber. Deutsch. Bot. Gesell., 1886, p. 184.
Buchtien— (Oophyte) Uhlworm and Haenlein's Biblioth. Bot., Heft 8, 1887.

U4 VASCULAR CRYPTOGAMS

Fossil Vascular Cryptogams.

Fossil remains or impressions of plants are found in all the stratified
geological formations from the Upper Silurian to the latest. Of the
Thallophytes that must certainly have existed in the seas from which
the oldest fossiliferous strata were deposited, the traces are, as might be
expected, few and doubtful ; and it is certain that many markings that
have been claimed under this category do not belong to the vegetable
kingdom at all. The remains of Vascular Cryptogams make their first
appearance in the Upper Silurian, and are remarkably abundant in
the Devonian and Carboniferous formations. During these periods
the arborescent vegetation of the globe consisted entirely of Vascular
Cryptogams and Gymnosperms, no remains that can be referred with
certainty to Angiosperms being known earlier than the Permian forma-
tion. The structure and mode of reproduction in Vascular Cryptogams
seem to have been remarkably uniform from the earliest times to the
present. The remains found in the fossil state belong, of course, ex-
clusively to the sporophyte generation ; but these indicate not only
that nearly every class of Vascular Cryptogams now in existence was
represented in the Carboniferous period, but also that none of the
primeval forms of vegetable life at present discovered presented charac-
ters differing very widely from existing types.

FOSSIL RHIZOCARPE^:.

The fossil remains that can be referred, with any degree of cer-
tainty, to the Rhizocarpeae are very scanty. A few leaves found here
and there have been described by their discoverers, under the names
Marsilidium(Schenk)and Sphenoglossum (Emm.), as representing genera
nearly allied to Marsilea ; and capsules presenting an external resem-
blance to the sporocarps of Pilularia and Marsilea have been found in
the Eocene.

The Salviniaceae are represented with much more certainty in the
Miocene, impressions of leaves found in various beds belonging to
that series being indistinguishable from those of Salvinia. More doubt
attends the identification of fructifications referred to this order.
Strasburger and Solms-Laubach think it possible that certain minute
echinate bodies found in calcareous nodules in the Carboniferous,
described under the names Traquairia (Carruth.), Zygosporites(WilL), and
Sporocarpon (Will.), the first of which is regarded by its discoverer as a

FOSSIL VASCULAR CRYPTOGAMS

115

Radiolarian Rhizopod, may be massulas of Azolla. Sir W. Dawson
(Bull. Chicago Acad. Sc., 1886, p. 105) refers organs of fructification ob-
tained from the Devonian (=Erian)in Canada and the northern United
States — and previously described, under the name Sporangites (Daws.),
as sporangia of Lycopodiaceae — to a genus nearly allied to Salvinia, which
he calls Protosalvinia ; but, inasmuch as they are borne on Lepidoden-
dron scales, this explanation is inadmissible. Sir W. Dawson believes
the megaspores of Rhizocarpeae to be the chief cause of the highly
bituminous character of the shales in which these bodies are found.

FOSSIL SELAGINELLACE^:.

Remains of arborescent vegetation more or less nearly allied to the
typical Selaginellaceae of the present day occur in extraordinary abun-
dance in the older fossiliferous strata. Of these the most abundant and
best known families are the Lepidodendreae and the Sigillarieae.

Of the LEPIDODENDREAE the stems are known as Lepidodendron, and
the fructification occasionally found in organic connection with the

FIG. 87. — A, B, C, portions of surface of stem of different species of Lepidodendron (natural
size) ; Z?, single cushion (magnified). (After Solms-Laubach.)

branches, as Lepidostrobus. The fructification is distinctly heterosporous ;
and although, in a large number of Lepidostrobus cones, microspores only
have been detected, this is unquestionably either because the portion con-
taining the megaspores has not been preserved, or possibly because the
megasporanges and microsporanges may have been distributed in distinct
fructifications — a degree of differentiation unknown in any existing form.
The remains of a large number of species of Lepidodendron occur in
the coal measures. They were trees, with stems up to ninety feet in
height and two feet in diameter, covered with the diamond-shaped scars
of fallen leaves. These scars, together with a portion of the leaf-stalk
remaining behind in the form of a cushion, occupied the whole surface
of the stem. Wherever the internal structure has been preserved, a

I 2

n6

VASCULAR CRYPTOGAMS

central 'vascular' cylinder can be detected, consisting of scalariform
tracheides. There is distinct evidence of a secondary growth in thick-
ness. The branching was always dichotomous. The leaves were very
similar to those of Lycopodium, and were penetrated by a single
-vascular' bundle.

The fructifications known as Lepidostrobus are cone-like structures,
not unlike fir-cones in appearance, consisting of densely packed sporo-
phylls. On the upper side of each leaf is a single sporange, often of
considerable size. The cones themselves vary in size from that of a
hazel-nut to one and a half feet in length. It is seldom that the remains
are in a sufficiently perfect condition for the structure of the spores to

A

I

FIG. 88. — A, transverse section of cone of Lepidostrobus Browmi Schimp. ; B, longitudinal section
(after R. Brown) ; C. diagrammatic longitudinal section of portion of cone of L. ornati4s Hook.
(after Hooker) ; D, upper surface of sporophyll {Lepidophylhun). (All from Solms-Laubach.)

be made out with certainty ; but in several examples both kinds occur.
Where one kind only has at present been detected, it is, in most cases,
the microspore, the megaspores being probably in the lower part of the
fructification, which has not been preserved or examined. In the mega-
s.pores the exospore has three ridges ; there are numerous spores in each
sporange. The microspores of L. dabadianus (Schpr.) are connected
together in groups of four ; while in L. Brownei (Schpr.) they are in threes.
More or less nearly allied to Lepidodendron are a number of other
arborescent genera, among the more striking of which are Ulodendron
(Stbg.), Bothrodendron (L. and H.), and Lepidophloios (Stbg.), all from
the coal measures.

FOSSIL VASCULAR CRYPTOGAMS

117

Although the genus Sigillaria is still placed by some writers among
Gymnosperms, its true place is undoubtedly near to Lepidodendron
in the order Selagineilaceae ; the structure of the stem presents no
important difference
from that of Lepido-
dendron, while the
fructification known as
Sigillariostrobus bears a
remarkable resemblance
to Lepidostrobus.

The remains of
various species of Sigil-
laria occur in enormous
•quantities in the coal
measures ; and they
constituted one of the
predominant forms of
vegetation of the period.
The stems rivalled in
height and thickness
those of Lepidoden-
dron, and were covered,
like them, with the
scars of fallen leaves in
linear series. They were
simple ordichotomousiy
branched. The scars

are circular, ovate, or hexagonal from mutual compression. In the
section known as Leiodermaria the cushions which occur in other forms
are wanting, and the scars stand out at a considerable distance from one
another on the smooth surface of the stem. The leaves, which are
occasionally found still attached to the branches, were narrow, linear,
and sedge-like, up to as much as one and a half feet in length, with a
projecting midrib. According to Van Tieghem the stem of Sigillaria
differs from that of the Lepidodendreae, and indeed from that of all
other Vascular Cryptogams, in the leaf-trace bundles being ( diploxy-
lous' — that is, in the central cylinder having an external secondary and
centrifugal as well as an internal primary and centripetal xylem. Renault
regards the Rkytidokpid^ or Sigillariae with stem exhibiting raised
cushions as well as scars, as Cryptogamic ; the Leiodermariece, or smooth-
stemmed Sigillariae, as Gymnospermic ; but this view is not supported
by a careful examination of the structure. .

D

FIG. .89. — A, B, C, portions of surface of stem of different species
of Sigillaria ; D, Leiodermaria. (After Solms-Laubach.)

Ji8 VASCULAR CRYPTOGAMS

Sigillariostrobus, the fructification of Sigillaria, is extremely rare. It
was a cone resembling Lepidostrobus, with the sporanges placed singly
on the base of the sporophylls. The sporophylls are broadly lanceolate
and apiculate. Only one kind of spore has at present been discovered,
the megaspores, but it may be regarded as certain that these were asso-
ciated with a second and smaller kind.

The fossils known as Stigmaria are the roots of Sigillaria, the two
having been not unfrequently found in connection with one another.
They occur in the Devonian and Carboniferous formations. Fragments
have been found from twenty to thirty feet or more in length (S. ficoides,
Brongn.), cylindrical and unbranched, or the branching always dichoto-
mous, the two branches running in a nearly parallel direction. The
surface is smooth, with numerous shallow saucer-like depressions, the
scars of the rootlets, some of which aje still very commonly found
attached to the primary root. The Stigmariae obviously lengthened

FIG. 90.— Stigmaria ficoides Brongn. with rootlets. (After Solms-Laubach.)

exclusively by apical growth. Transverse section shows a hollow
' vascular ' cylinder, broken by meshes for the passage of the bundles
of the rootlets, and consisting of scalariform tracheides with a central
parenchymatous tissue or ' medulla.' In the rootlets the single central
bundle consists of a few scalariform tracheides, which leave the cylinder
as a triangular bundle, but become circular in the rootlets.

Under the term LYCOPODITES are included a number of fossil forms,
the fructification of which is either entirely unknown, or is not in a suf-
ficiently well-preserved state for definite determination. Some of the
leafy stems ought possibly to be referred to Coniferae ; others, with
leaves of one kind only, perhaps belong to Lycopodiaceae ; while others,
with leaves of two different kinds, are Selaginellaceae. From beds near
the bottom of the Carboniferous series there is a species with thick
club-shaped terminal fructification, bearing a striking resemblance to
Lycopodium Phlegmaria (Lycopodites Stockii, Kidst). Ptilophyton

FOSSIL VASCULAR CRYPTOGAMS

119

(Daws.), from the Devonian and Carboniferous formations of Scotland
and North America, should also be included here.

The only fossils that can be referred with any degree of certainty to
the Isoeteae are those comprised in the genus Isoetites (Schmp.), from the
Miocene, which is scarcely distinguishable from existing Isoetes. More
doubt rests on the true place of Solenites (L. and H.), from the Jurassic,
which has been referred with equal probability to Gymnosperms.

Of fossil Psiloteae the remains are few and uncertain. To this family
has been referred Psilophyton (Daws.) ; but the fructification is very

FIG. oi.—

91. — Bases of stem of Sigillaria, with Stigmaria roots attached. (After Solms-Laubach.

aberrant from the existing Psiloteae, consisting of a pair of pod-like
capsules at the end of special branches.

FOSSIL FILICES.

The remains of ferns— or more commonly the impressions of the
leaves — are found in all fossiliferous strata from the Devonian on-
wards. Great difficulty is presented in the classification of fossil ferns
by the small fragments in which they are usually found, anything like
an entire plant, or even a number of fronds attached to an aerial stem

120

VASCULAR CRYPTOGAMS

or rhizome, being extremely rare. The great majority of species appear
to have been herbaceous ; or at all events the stems of tree-ferns are

not of very common occur-
rence, even in the coal
measures. And although the
fructification has frequently
been met with, the vast ma-
jority of the leaves of which
the remains or the impres-
sions have been preserved
are barren. The only avail-
able system of classification of
the greater number of fossil
ferns is based on the mode of
venation, on which character
a number of families have
been founded by Brongniart ;
but it is doubtful whether
this has any great value as a
natural system of classifica-
tion. A form of heterophylly
different from anything which
occurs among existing ferns
is found in a few species from
the Carboniferous formation,
where, in addition to the
normal pinnae of the frond,
themselves again pinnate, im-
perfect pinnae of much smaller
size and simpler structure are
intercalated between them.

These imperfect pinnae, known as aphkbice, were described as distinct
species before their true character was known. Thus Rhacophyllum
adnascens (L. and H.) is the aphlebia of Sphenopteris crenata (L. and
H.) ; while various so-called species of Cyclopteris are abnormal pinnae
springing from the rachis below the normal pinnae of Neuropteris.
On the whole, the leaves of ferns belonging to the Carboniferous period
bear a striking resemblance to those of our own day ; in many cases
they might belong to living genera.

The remains of the fructification of fossil ferns that have come down
to us lead us to believe that the existing orders of Filices may have been
represented in the earlier geological periods \ and none have as yet been

FIG. 92. — AphleMa, from the Carboniferous formation,
i, Sphenopteris crenata L. and H. ; 2, 3, Rhaco-
adnascens L. and H. (After Schimper.)

FOSSIL VASCULAR CRYPTOGAMS

121

discovered that cannot be referred to some existing type. The preva-
lent forms appear to have been the Polypodiacese, Hymenophyllaceae,
and Marattiaceae ; this last order having been apparently much more
widely distributed and more abundant in the earlier periods than it is
now.

The HYMENOPHYLLACE^: may possibly have been one of the earliest
differentiated types. In Palaeopteris hibernica (Schmp.) (Cyclopteris

VIG. 93. — A, frond of Palceopteris hibernica Schmp. (restored) (-^-6) ; B, pinnule (somewhat mag.) ;
V, fertile pinna (nat. size) ; D, two cup-shaped indusia attached to the filiform midrib (mag.) ; E,
sporanges of a hymenophyllaceous fern from the coal measures (mag.). (After Carruthers.)

hibernica, Forbes), specimens have been found in which all the lower
pdnnag are fertile. The pinnule was reduced to a midrib supporting the
slender stalks of the bilabiate cup-shaped indusia ; and the stalk is con-
tinued into the indusium, to which the sessile sporanges are attached.
The texture of the frond was not membranaceous, like that of most exist-
ing Hymenophyllaceee, but was more like that of Loxsoma. On the
rachis between the pinnae are seated single large decurrent pinnules.

122

VASCULAR CRYPTOGAMS

The edges of the pinnules are slightly serrate from the numerous dicho-
tomising veins ; the lower part of the stipe is clothed with scales. Spo-
ranges with the characteristic oblique annulus of the Hymenophyllaceae
have also been found in the coal measures by Carruthers ('Geol. Mag.,'

Feb. 1872).

Remains which can be
referred with certainty to the
MARATTIACE^E are not unfre-
quent. In Scolecopteris (Stur)
we have a true synange ; the
separate sporanges, arranged
on a common elevated re-
ceptacle, are linear-ovate with
a long free apex, and open by
a fissure on the inner side
without any trace of an an-
nulus. In Asterotheca (Presl)
the circular sorus usually con-
sists of six exannulate spo-
ranges closely adnate to one
another, the sori are sessile,
and are arranged in a single
row on each side' of the mid-
rib of the pinna. In Renaultia
(Stur) a group of cells occurs
in the outer wall of the spo-
range similar to that in Angi-
opteris, which may be the
rudiment of an annulus.
Seftenbergia (Cord.) presents
important differences. The
sporanges are not collected
into sori, but are scattered
along the veins of the third
order ; each sporange has at
its apex a cap-like annulus.
It appears to be a connecting
link between the Marattiaceae
and Schizaeaceae. Other types of Marattiaceae are presented by Danaeites
(Gopp.) and Botryopteris (Ren.).

The remaining types of ferns of the Devonian and Carboniferous,
and especially those of more recent periods, present the greatest resem-

FIG. 94. — Fructifications of fossil Marattiaceae. A,
Seftenbergia ophidermatica ; B, Haulea Miltoni;
C, Oligocarpia Lindsceoides ; D, Scolecopteris poly-
morpha; £, Asterotheca. Sternbergii. (After Solms-
Laubach.)

FOSSIL VASCULAR CRYPTOGAMS

123

blance to POLYPODIACE^E and CYATHEACELE among existing forms. No
fructification resembling that of Osmundaceae has at present been dis-
covered ; but Osmundites (Carruth.), from the Lower Eocene, has been
referred to that order by its discoverer from the peculiarities of the
structure of the stem. The Ophioglossacese are still unrepresented in
palseophytology.

The internal structure of the stem and leaf-stalk of most fossil ferns,

FIG. 95. — Section of Stemmatopteris Cord, invested with roots=Psar0nhts Cord.
(From a specimen in the British Museum.)

where this can be determined, differs in no important respect from that
of living forms. We find the same interrupted ring of 'vascular'
bundles, which may be either concentric or collateral, the xylem con-
sisting largely of scalariform tracheides, the same layers of sclerenchyme
both in connection with the bundles and beneath the epiderm ; evident
indications of gum-passages have even been detected. But though this
is by far the most common type of structure, a second is displayed in a
few rare examples, in which the arrangement of the ' vascular ' elements.

124 VASCULAR CRYPTOGAMS

may be compared to that in the stem of Monocotyledons, as the ordinary
arrangement maybe to that in the first year in the stem of Dicotyledons.
In Stemmatopteris (Cord.) (including Psaronius, Cord., and Zippea,
Cord.), from the Bath coal-field, the circumference of the stem is com-
posed of a continuous envelope of sclerenchymatous tissue, within which
are perpendicular tracts of ' vascular ' tissue not penetrated by meshes.
Between these tracts the leaves were given off in perpendicular series,
the large single leaf-bundles coming right out from the central paren-
chyme, in which they existed as well-formed bundles, filling up more or
less completely the central cavity (see fig. 95). There is therefore no
closed cylinder with central * medulla ' as in ordinary ferns. By some
authors it has been proposed to establish "the fern-stems which display
this character as a separate group under the name Psaronieae, but there
is every reason to identify the stem of Stemmatopteris insignis (Cord.)
with the fronds of Pecopteris arborescens (Schl.), which bear fructi-
fication indistinguishable from that of Cyathea ; and, this character
being the more important, the genus must be placed under Cyathe-
aceae.

FOSSIL EQUISETACE^:.

Remains of the genus Equisetites, evidently very nearly allied to
Equisetum, if not identical with it, are found in greater or less abun-
dance in various strata from the Carboniferous to the Tertiary, attaining
their maximum development in the Trias. The stems of these fossil
horsetails are from one and a half to six inches in diameter, and may have
attained a height of from twenty-five to thirty-five feet. They are cylin-
drical, and are marked with alternate ridges and furrows. At the nodes
are tubular leaf-sheaths split at the margin into numerous short teeth,
each of which terminates in an elongated bristle ; in some species the
number of these teeth appears to have amounted to as many as one
hundred. The nodal diaphragms are clearly seen in E. arenaceus
(Brongn.), the remains of which occur in extraordinary abundance in the
Upper Trias ; and, in some species at least, the furrows and ridges of
each internode are alternate respectively with those of the internodes
next above and next below. Remains of rhizomes have been found closely
resembling in structure those of Equisetum. Nearly allied to Equise-
tites are the genera Schizoneura (Schmp.) and Phyllotheca (Brongn.);
the latter differing from the type in its spreading sheath-teeth, and in
the ridges and furrows of adjacent internodes not being alternate. The
fructification of Equisetites has only been found in a very imperfect con-
dition. That of Phyllotheca bears "a close resemblance to the cone-

FOSSIL VASCULAR CRYPTOGAMS

125

like sporangiferous spikes of Equisetum. It contained spores of one
kind only.

The group of CALAMARIE/E — including the stems known as Cala-
mites and Calamodendron^ and the fruit known as Calamostachys —
have been separated by some authorities from the Equisetaceae on the
ground of their alleged heterospory, but without sufficient warrant from
the facts of their structure as actually observed.

The remains of Calamites occur in immense quantities in the Car-
boniferous strata ; apparently they
constituted one of the most im-
portant features of the vegetation of
that period, disappearing after the
Permian. The stems were fre-
quently of gigantic dimensions com-
pared with our existing Equisetums,
attaining a height of thirty feet and
a diameter of four inches or more.
They consist of a hollow central
cavity, with a cylinder of tracheides
in wedge-shaped bundles, separated
at their origin by parenchyme, and
alternating at the nodes, where there
is a diaphragm or ' phragma.' The
leaves, which spring in whorls from
each node, do not, as in Equi-
setites, coalesce laterally into sheaths
surrounding the stem. They are
narrow and acicular, with a single
prominent midrib. At the nodes
are occasionally seen saucer-shaped
depressions, the scars of the lateral
branches, which are sometimes
found attached to the primary axis.
The growth of the stem is characterised by a considerable secondary
increase in thickness ; and, since this phenomenon was formerly un-
known among living Vascular Cryptogams, it has induced some authori-
ties to transfer those examples where it occurs, under the name of
Calamodendreae, to Gymnosperms ; but this has been rendered un-
necessary from the fact that a secondary growth in thickness occurs
also in Lepidodendron and Sigillaria, as well as in Isoetes; and is
further contradicted by the fact that fructification of an evidently
cryptogamic character has been found in organic connection with stems

FIG. 96.— A, Phyllotheca eqriisetiformis ; B,
fructification of Phyllotheca, (After Solms-
Laubach.)

126

VASCULAR CRYPTOGAMS

which must be referred to the same group. To the same family as
Calamites belong probably Astromyelon (Will.), and at least some
species of Arthropitys (Gopp.). The degree of identity in structure of
Calamodendron with Calamites is a point on which the best authorities
are not yet in agreement.

To the genus Calamitina (Weiss) (Asterophyllites, Ren., Calamocladus,
Schmp.) belong a number of calamite stems found with the leaves still
in connection with them. These are of very peculiar form, consisting
of an ovate-lanceolate basal portion, thickened and marked by a central
furrow, and a narrowly-lanceolate acuminate apical portion ; the basal

FIG. 97.— Stems of Calamites. (After Weiss.)

portion alone being very frequently preserved. The leaves do not
coalesce laterally into sheaths ; on falling off they leave behind whorls
of round or ovate scars. Bornia (Brongn.) (Archaeocalamites, Stur) is
an older fossil occurring in the Devonian formation, differing from the
more recent forms in the broad flat longitudinal ribs on the stem not
alternating in adjacent internodes.

In Annularia (Brongn.), which occurs only in the Carboniferous
formation, the leaves are linear- lanceolate, and are penetrated by a single
' vascular ' bundle ; those of each whorl are united laterally in their
basal portion into a shallow saucer-shaped cup, through which the stem

FOSSIL VASCULAR CRYPTOGAMS

127

passes, and from the margin of which spring the linear-lanceolate free
portions of the leaves. Annularia has been regarded by some writers
as an herbaceous aquatic plant ; but there is little doubt that it is the
branches and foliage of Calamites.

The fructification of the Calamarieae, described under the name
Calamostachys — with which must be identified Volkmannia (Stbg.) and

FIG. 98. — Leaves of Calamitina.
(After Weiss.)

\

FIG. 99. — ArchiPOcalamites radiatus Stur
(After Stur.)

Bruckmannia (Stbg.) — has not unfrequently been found in organic con-
nection with the stem. Each cylindrical cone-like fructification consists
of a number of whorls of sporophylls, but differs from that of Equisetum
or of Equisetites in the fertile whorls alternating, in each spike, with
barren whorls consisting of a large number of lanceolate acute leaves,
free or more or less connate at the base ; the free portions completely
cover the next upper fertile whorl and the base of the barren whorl

I'28

VASCULAR CRYPTOGAMS

above that ; thus giving a remarkable superficial resemblance to a fir-
cone. The sporophylls of each whorl are not united with one another ;
they resemble those of Equisetum in their peltate form, and each bears
on its under side four sporanges. It is very rarely that the spores are
preserved in sufficient perfection for their structure to be made out with
certainty. The statement that they are of two kinds, megaspores and
microspores, rests on insufficient evidence. Carruthers believes that he
has detected in a few cases an outer separable membrane which would

FIG. 100. — A, Fructification of Cingularia typica; B, portion of a barren and of a fertile whorl
C, upper surface of fertile whorl. (After Weiss.)

unroll itself in the form of elaters. In Palaeostachys (Weiss) the spo-
rophylls stand in the axils of the barren leaves. The fructification of
Cingularia (Weiss) has a very remarkable appearance, from the alternate
barren and fertile whorls standing out nearly at right angles to the axis ;
the leaves of the barren whorls are connate for about half their length ;
the sporophylls are also united in each whorl into a horizontal plate,
divided at the margin into truncate lobes ; from the under side of this
plate the sporanges hang vertically in radial rows. The remains of
Cingularia fructifications are found in large numbers in the coal

FOSSIL VASCULAR CRYPTOGAMS

129

measures. Very little is known of their stem, which appears, however,
to have resembled that of the Calamarieae.

More doubt rests on the affinity with the Equisetaceae of the group
of SPHENOPHYLLE^E. The remains of Sphenophyllum (Brongn.) are
found in abundance in the Carboniferous formation, but do not come
down to more recent times
than the Lower Permian.
The stem is divided into
distinct nodes and inter-
nodes, the latter usually
marked with conspicuous
ridges and furrows, which
are not alternate in adja-
cent internodes, but pass
continuously through the
nodes. At the swollen
nodes are whorls of leaves,
with occasional axillary
branches. Each whorl ap-
pears to consist always of
six leaves or of some mul-
tiple of six. They are ses-
sile, and obcuneate from a
narrow base, sometimes
denticulate and bifid at the
apex, but are not in any
degree connate. Each leaf
contains a number of
simple or dichotomous
'vascular' bundles. In
the centre of the stem is
a triangular bundle com-
posed of scalariform tra-
cheides, to which some
authorities add spiral tra-
cheides and others with
bordered pits ; the bundle passes through the node without material
change. This is often surrounded by some layers of secondary wood ;
the greater part of the stem, on transverse section, is occupied by a
small-celled parenchyme.

The fructification of Sphenophyllum consists of cylindrical cone-
like spikes resembling those of Calamites. It is composed of whorls

FIG. loi.— i, 2, Fructification and branch of Asterophyl-
lites; 3, 4, fructification and branch of Annnlaria ; 5,
6, fructification and branch of Sphenophyllum. (After
Carruthers.)

I3o VASCULAR CRYPTOGAMS

of sporophylls without any intermediate barren whorls ; the separate
leaves are often saccate, the narrow apices ascending and covering in an
imbricate fashion the bases of the next upper whorl. The position of the
sporanges differs materially from that of the other Equisetaceae. They
are comparatively large bodies, lenticular, from i to 2*5 mm. in diameter,
solitary and sessile in the saccate hollow on the upper surface of the
base of the sporophyll. The solid remains have not yet been found in
a sufficiently perfect condition for the structure of the spores to be
determined with any degree of certainty, but no sufficient evidence of
heterospory has been presented.

From the form and position of the sporanges the Sphenophylleae are
placed by some writers under Selaginellaceae ; but in the general appear-
ance and structure of the vegetative organs they approach so nearly to
the Calamarieae that it seems best at present to place them here until
we are better acquainted with the details of the fructification. Stur has
recently described and figured specimens with leaves of Asterophyllites
at the base, Sphenophyllum -leaves higher up, and terminating in a fructi-
fication.

LITERATURE OF FOSSIL VASCULAR CRYPTOGAMS.

Sternberg— Flora der Vorwelt, 1821-1838.

Brongniart— Hist, des Vegetaux Fossiles, 1820-1840; (Sigillaria, Stigmaria, and

Lepidodendron) Arch. Mus. d'Hist. Nat., 1839.
Lindley and Hutton— Fossil Flora of Great Britain, 1833-1837.
Witham — Internal Structure of Fossil Vegetables, 1833.

Goppert— Systema Filicum Fossilium, 1826 ; Gattungen der fossilen Pflanzen, 1841.
Unger — Genera et Species Plantarum Fossilium, 1840.
Corda— Beitr. zur Flora der Vorwelt, 1845.

Hooker— Vegetation of Carboniferous Period, in Mem. Geol. Survey, 1847.
Brown — Triptosporites, in Linn. Soc. Trans., 1851.
Geinitz — Steinkohlenformation in Sachsen, 1855.
Ludwig— Calamiten-Friichte Palseontographia, 1861.
Goldenberg— Flora Saraepontana, 1862.

Binney — Fossil Carboniferous Plants, Palseont. Soc., 1868-1875.
Schimper — Paleontologie vegetale, 1869-1874.
Weiss — Fossile Flora der Steinkohlenformation, &c., 1869 ; Beitr. zur fossilen Flora,

1876-1884.
Carruthers— (Ulodendron and Bothrodendron) Monthly Micr. Journ., 1870; (Lycopo-

diacese) 1869; (Calamites) Seemann's Journ. Bot., 1867.
Dawson-Fossil Plants of Upper Silurian and Devonian of Canada, 1871-1882;

Geological Hist, of Plants, 1888.
De Saporta— Paleontologie Fra^aise, 1873.
G rand 'Eury— Flora Carbonifere du Dpt. de la Loire, &c., 1877.

FOSSIL VASCULAR CRYPTOGAMS 131

Renault — Cours de Bot. fossile, vols. i.-iii., 1881-1883.

Williamson— Organisation of Plants of the Coal Measures, Phil. Trans. 1871-1888 ;

(Stigmaria) Pakeont. Soc., 1887.

Kidston — (Lepidodendron, Sigillaria, &c.) Ann. and Mag. Nat. Hist., 1885.
Lesquereux — Coal Flora of Carboniferous Formation of Pennsylvania, &c., 1884.
Stur— Carbonflora der Schatzlarenschichter, 1885 ; Culmflora, 1877-1883.
Van Tieghem— Bull. Soc. Bot. France, 1883, p. 169.
Zeiller— Ann. Sc. Nat. (Bot.), 1884; (Sigillaria) do., 1884, p. 256.
Zittel— Handbuch der Paloeontologie, 1879-1885.
Solms-Laubach — Einleitung in die Palaeophytologie, 1887 (for which see very copious

bibliography).
Schenk — Die fossilen Pflanzenreste, in Schenk's Handb. der Botanik, vol. iv., 1888.

K 2 .

132 M US CINE &

SECOND SUBDIVISION.
MUSCINE^.

THE line of demarcation between the Vascular Cryptogams and the

plants immediately below them in the scale of organisation, the

Muscineae, is a very sharp one, and their genetic relationship to one

another presents considerable difficulties. The lower type of structure

is, however, chiefly manifested in the vegetative organs. The mode of

sexual reproduction which occurs throughout this group corresponds in

its most important features with that in Vascular Cryptogams ; and we

have here also a division of the life-history of the plants into a sporo-

phyte and an oophyte generation, a true alternation of generations,

although the phenomenon differs in one important point from that which

we have seen in Vascular Cryptogams, viz. in almost the whole of the

vegetative system belonging to the oophyte instead of to the srjorophyte

generation. To this we have already seen an approach in Gymnogramme

(p. 65). The vegetative system is invariably of small size, and almost

entirely destitute of vascular bundles and of all other strengthening

tissues. Within the group the boundary line is crossed between Cormo-

phytes and Thallophytes ; and in the lower orders we entirely lose the

differentiation of the vegetative organs into cauline and appendicular

organs — in other words, into stem and leaves ; the entire vegetative

system consisting of an undifferentiated thallus. The mature plant is

almost invariably terrestrial in habit, and is attached to the substratum

by rhizoids. The appendicular organs, when present, are minute leaves,

which never contain true vascular bundles, and usually consist of only a

single layer of cells. We find, however, the first stage towards the

epidermal and fibrovascular structures characteristic of the leaves of

vascular plants, in a distinct midrib and edging of elongated cells with

somewhat thicker cell-walls overlapping one another at the extremities,

and partially or altogether destitute of chlorophyll. In one group

(Sphagnaceae) the leaves are composed of cells of two different kinds,

small cells containing chlorophyll interspersed among much larger empty

cells. The leaves, being usually unilamellar, cannot, of course, be pro-

MUSCINEAE 133

vided with stomates, though these are frequently present on the organs
of propagation ; while one group of thalloid forms (Marchantiacese)
possess stomates of remarkable and complicated structure. The vegeta-
tive propagation of the Muscineae takes place in several ways : ist, by
innovation, i.e. by a process of renewal at the apex, while the oldest parts
die off behind ; 2nd, by means of gemmae, stolons, or detached buds ;
and 3rd, by the non-sexual production of a thallus or protoneme, a
process which will be described presently. The facility of these various
modes of vegetative multiplication gives rise to the tufted or caespitose
habit of many species.

Notwithstanding the variety in the development of the vegetative
structure, the sexual organs of Muscinese are remarkably uniform in
their main features. The male and female organs are termed respec-
tively, as in Vascular Cryptogams, antherids and archegones. The
mature antherid is a spherical, ellipsoidal, or club-shaped body, with a
longer or shorter stalk, the outer layer of its cells forming an enclosing
wall, while each of the small and numerous crowded cells in the interior
develops an anther ozoid. These bodies are spirally-coiled threads of
protoplasm, thicker at the posterior end, and tapering to a fine point
at the anterior end, where they are furnished with two long fine cilia,
the vibrations of which set them in constant motion ; they are set free
by the rupture of the wall of the antherid at its apex. The archegones,
when in a condition capable of impregnation, are flask-shaped bodies
bulging from a narrow base, and produced above into a long neck.
The swollen or ventral portion, the venter, encloses one cell much
larger than the rest, the central cell, from the larger and lower portion
of which is developed, after its separation by a horizontal septum, the
germ-cell or oosphere. Above this central cell is an axial row of cells
termed the canal-cells, passing through the narrow portion or neck of
the archegone, and continued as far as the apical cells, stigmatic cells,
or lid-cells, which form what is called the stigma. These canal-cells
are transformed before impregnation into mucilage, which finally swells
up and forces apart the four stigmatic cells, an open canal being thus
formed, through which the antherozoids reach the oosphere. Notwith-
standing the general uniformity in structure of the sexual organs of the
Muscineae, their origin varies greatly. They may originate, in the
thalloid forms, below the growing apex, from the superficial cells of the
thallus, or on special metamorphosed branches ; in the foliose forms
both antherids and archegones may be formed from the apical cell of
the shoot, or from segments of it ; and in this case they may take the
place of leaves, of lateral shoots, or even of hairs. According to
Leitgeb, the order of evolution from the lower to the higher forms of

i34 • MUSCINE^E

Muscineae is indicated by the position of the sexual organs on the
vegetative shoots ; as these organs approach nearer and nearer to the
apex, the shoot gradually loses its vegetative character, and becomes
differentiated into a special fertile branch.

The sexual organs are frequently surrounded by crowded and slightly
modified foliar structures, the whole arrangement having then some
resemblance to the flower of Phanerogams. Thus, in the thalloid
forms, the antherids and archegones are commonly borne on umbrella-
shaped outgrowths of the thallus which are not inaptly termed respec-
tively male and female inflorescences. In the foliose forms they are
frequently arranged at the extremities or laterally on branches, and
closely surrounded by small leaves constituting the perichcete or perianth,
reminding one of the bracts, or even of the calyx, of Flowering Plants,
the whole structure forming an hermaphrodite, monoecious, or dioecious
' flower.' They are often accompanied by barren, hair-like cells, termed
paraphyses.

The first result of the impregnation of the oosphere by an anthero-
zoid is the formation of an ovoid embryo by repeated cell-divisions ;
this continues to grow at its apex, and finally develops into the
fructification here known distinctively as the sporogone, the ultimate
form of which varies greatly in the different families. In its most
perfect form the sporogone is differentiated externally into a slender
stalk or seta, which penetrates into the base of the archego-ne, or even
into the underlying tissue, and a spore-capsule, called indifferently the
sporange, theca, or urn. Along with the spores the spore-capsule some-
times contains (in the Hepaticse) elongated cells thickened by a single
or double spiral band known as elaters, which assist in the dissemination
of the spores. The mature sporange is, in the highest forms, sur-
mounted by a cap or calypter, which becomes completely detached at
its base, while the mature lower portion of the archegone encloses the
base of the seta in the form of a sheath or vagine ; in the lower forms
the spore-capsule always remains enclosed in the calypter. The spores
of the Muscineae are always formed in fours within the spore-mother-
cells, which latter are produced within the cavity of the sporange by free
cell-formation, from a special layer or layers of cells known as the
archespore. When ripe they have a double cell-wall, the outermost
layer or exospore being provided with small excrescences, and the inner
layer or endospore bursting through it on germination. The contents
consist of protoplasm, chlorophyll-grains, starch, and oil.

The thalloid or leafy plant (as the case may be) does not, as a rule,
arise immediately from the germinating spore, but, in all the higher
forms, only after the previous formation of a colourless confervoid or

MUSCINE^E 135

filamentous structure, the prothallus or protoneme, on which the leafy
plant containing chlorophyll arises as a lateral shoot. The Muscinese
present, therefore, an illustration of the phenomenon of alternation of
generations ; the sexual generation which intervenes between germina-
tion and impregnation, or oophyte, consisting of the protoneme (when
present), the leafy (or thalloid) plant, together with the sexual organs ;
the non-sexual generation intervening between impregnation and ger-
mination, or sporophyte, consisting of the sporogone only with its
spores.

The Muscinese are divided into two well-marked families, the Musci
or Mosses, and Hepaticce. or Liverworts. In the Musci the immediate
result of the germination of the spore is always a protoneme consisting
erf branched rows of green or colourless cells, and often growing for a
considerable time independently, even after it has produced leafy stems
by lateral budding. The vegetative structure is always cormophytic,
and consists of a filiform stem furnished with two, three, or four rows of
leaves, not exhibiting any distinct bilateral structure, and branching
monopodially, never dichotomously. The sporogone is only for a time
enclosed in the calypter, which is usually eventually ruptured below, the
lower portion developing into the vagine, while the upper part is elevated
above the apex of the sporogone in the form of a cap. The spore-
mother-cells are produced from one or more special layers of tissue
within the sporange, the archespore, while the axial mass develops into
a solid columel. The uppermost portion of the wall of the sporange
forms a lid or opercule, which usually becomes detached from the lower
portion, to which the term theca or sporange specially belongs, to allow
the escape of the spores. The outermost layer of cells of the wall of
the sporange is more or less completely differentiated into an epiderm,
which is frequently penetrated by stomates. When the opercule is
removed, the rim of the sporange is either quite smooth, when it is
termed gymnostomous, or the edge is furnished with delicate hair-like
appendages, constituting the peristome, arranged in a single row or fre-
quently in two, when they are called respectively teeth and cilia, the
former constituting the outer, the latter the inner row. The number of
both teeth and cilia is always a multiple of four, or more correctly speak-
ing, a ' power ' of two. In the Hepaticae the protoneme is either scantily
developed or is altogether suppressed. The rest of the sexual generation
consists either of a flat dichotomously branched thallus or thalloid stem,
or of a slender stalk furnished with two or three rows of leaves. In the
division into Foliose and Thalloid or Frondose forms, the Hepaticse
therefore present the transition from Cormophytes to Thallophytes. The
mode of growth is always distinctly bilateral ; the thalloid forms cling

136 MUSCINE^E

closely to the ground or to some other substratum ; and even in the
foliose forms there is a well-marked tendency to the differentiation of an.
upper or dorsal and an under or ventral surface. The non-sexual
generation or sporogone remains surrounded by the calypter until the
spores are ripe ; the calypter is usually at length ruptured at the apex,
and remains at the base of the sporogone as an open sheath, while the
sporange projects above its apex to allow the escape of the spores. The
mother-cells of the spores are either developed from the whole of the
archespore, or, in most families, some of the cells develop into elaters ;
there is no columel.

LITERATURE.

Hofmeister — On the Germination, Development, and Fructification of the Higher

Cryptogamia, Ray. Soc., 1862.
Leclerc du Sablon., Ann. Sc. Nat, 1885, p. 126; and Bull. Soc. Bot. France,

1885, pp. 30 and 187.
Goebel— Die Muscineen, in Schenk's Handbuch der Botanik, vol. ii., 1882.

Class VII.— Musci.

The germinating spore of Mosses gives rise to a prothallium which is
always in the typical families of a filamentous conferva-like character,
and is hence known as the protoneme. On this is produced the leafy
plant with differentiated stem and leaves by lateral budding. These
together, therefore, constitute the sexual generation or oophyte, which
terminates in the production of the sexual organs. From the fertilised
oosphere proceeds the sporogone^ which comprises in itself the non-sexual
generation or sporophyte.

The protoneme first originates, in typical mosses (Bryacese), as a
tubular bulging of the endospore or inner coat of the spore, divisions
taking place in it in the transverse direction only. It has an unlimited
power of apical growth, and often branches copiously, forming a dense
felt of considerable size above or below the surface of the soil, in the
former case densely filled with chlorophyll. The protoneme usually
disappears altogether after the appearance on it of the leafy plant ; but
in some cases, especially in the Phascacese, it remains vigorous even
.after the formation of the sporogone. In the Sphagnaceae the proto-
neme consists of a flat plate of cells ; while in the Andreaeaceae cell-
division begins to take place within the spore, the resulting prothallium
consisting of a small cellular tissue. The buds which develop into the

MUSCI

T37

leafy stems appear never or very seldom to arise at the apex of a primary
filament of the protoneme, but always as lateral branches.

Mosses display a certain amount of differentiation of tissues. The
apical cell of the stem is, except in Fissidens (Hedvv.), a three-sided

FIG. 102.— Catharine 'a (AMckttm) ttndulata W. and M. (magnified). (After Schimper.)

pyramid. The primary meristem of the stem, situated beneath the
growing point, which develops into the permanent tissue, usually becomes
differentiated into an inner and a peripheral mass ; the latter, although

I38

MUSCINE&

not strongly defined, partaking of an epidermal character ; the bright red
or yellow cell-walls are considerably thicker than those of the central thin-
walled large-celled fundamental tissue. In some genera a further differen-
tiation takes place of the axial portion of the central cylinder into a
rudimentary ' vascular ' bundle with thicker cell-walls ; similar rudimen-
tary bundles being also formed in the pedicel of the sporogone. Both
the partially lignified and the thin-walled cells have simple pits in their
cell-walls ; these are found in all families of mosses, and are especially
abundant in the midrib of the leaves. Some species of Sphagnum (L.)
have rudimentary sieve-plates. The central bundle in the stem of Mnium,
Polytrichum (L.), and other genera, has been shown by Haberlandt not
to possess any of the strengthening functions of a true vascular bundle, but

FIG. 103. — A, germinating spore of Fnnaria. hygrometrica. L. (x 550) ; s, exospore ; iu, rhizoid ; r,
vacuole. B, portion of protoneme ( x 90) ; K, rudiment oi leafy axis ; w, rhizoid. (After Goebel.)

to be constructed for the purpose of the conduction of water. Its cells con-
tain nothing but a watery fluid, without starch-grains, oil, or protoplasm.
In genera which have no such central bundle, like Dicranum (Hedw.)
and Leucobryum (Hpe.), the epidermal tissue of the stem and branches,
with its perforated cells, forms a similar capillary apparatus. In the
more highly developed mosses, Haberlandt notes the following dis-
tinct tissues :— (i) an epidermal tissue, sometimes developing trichomic
structures ; (2) a mechanical system, consisting of elongated cells with
thickened walls ; (3) an absorbing system, most strongly displayed in
the rhizoids — also at the base of the sporange ; (4) an assimilating system,
often composed of palisade-cells, in the leaves or in the sporange; (5)
a conducting system, consisting of the rudimentary ' vascular ' bundles;

MUSCI

139

(6) a reserve-system, usually represented by the aquiferous tissue; (7)
a secreting system, developed typically in the sporange. No special
secretory or excretory organs have been detected in mosses.

The leaves of mosses originate as broad papillose bulgings of a cell
of the stem which becomes cut off by a septum. They are always of
small size, sessile, and vary in shape from extremely narrow to broadly
lanceolate or almost orbicular. The tissue of the greater part of the
leaf usually consists of only a single layer of cells,
all of which contain chlorophyll, except in the
Sphagnaceae and in Leucobryum, where the cells are
of two different kinds, one large and empty, the other
very small and chlorophyllous, thus giving the leaf
a very light yellow-green colour. In most mosses
the marginal cells of the leaf, and a row extending
through the middle of the leaf from the base to
the apex, are much smaller, and are disposed in
several layers, though still thin-walled, thus consti-
tuting the rudiments of an epiderm and midrib.
The midrib may even extend beyond the apex of
the leaf as an awn or bristle. The leaves are usually
crowded, especially in the neighbourhood of the
sexual reproductive organs. Their phyllotaxis is
spiral, or more rarely distichous. The branch-
ing of the stem of mosses is apparently neither
dichotomous nor axillary ; the number of lateral
shoots is always much smaller than that of the leaves.
When the primary shoot produces a so-called
' flower ' at its apex, a lateral shoot situated beneath
it not unfrequently displays a more vigorous growth
of a monopodial character, and is then termed an
innovation. Prolification, or the prolongation of a
shoot by the continued growth of the bud within and
above the male ' flower,' is a common phenomenon
in Polytrichum. Nearly leafless shoots or stolons
are sometimes formed beneath or on 'the surface of
the ground, arising finally as erect leafy stems.

In most mosses large numbers of rhizoids are formed on the under
side of the stem, often clothing it completely with a reddish brown felt
(see fig. 102). They differ from the protoneme in their tendency to grow
downwards, and in not usually containing chlorophyll ; but there is no
sharp distinction between the two, each possessing the power of pro-
ducing branches indistinguishable from those of the other.

o
nified)!11

140

MUSCINE&

The non-sexual propagation of mosses takes place in a variety of
ways, the first step being, in nearly all cases, the production of a colour-
less filament of the nature of a protoneme. This protonemal branch, like
the true protoneme which springs from a spore, may produce by lateral
budding a number of leafy shoots. Protonemal branches of this kind
are in some genera (such as Mnium, L., Barbula, Hedw., and Phascum,

L.) produced in large num-
bers simply by turning over
a tuft of moss on the soil.
In this state they frequently
hibernate, the portion above
the soil disappearing entirely.
In some mosses the leaves
produce a protoneme simply
by the growth of particular
cells into segmented fila-
ments ; and this may even
take place with detached
leaves if kept moist. The
seta or stalk of the sporogone
has a special tendency to
produce protonemes when
in contact with damp soil.
Rhizoids also may give rise to
gemmae or leaf-buds, whether
above or beneath the surface
of the soil. Gemma of a more
complicated structure occur
in a few species, as Aulacom-
nion androgynum (Schw.)
(Bower, 'Journ. Linn. Soc.,'
1884, xx., p. 465), and Tetra-
phis pellucida (Hedw.), being
stalked fusiform or lenticular
multicellular bodies. In the

latter species they are enveloped in an elegant cup or cupule, composed of
a number of leaves, out of which they eventually fall, and then put forth
protonemal filaments, which give rise first to a flat prothallus resembling
that of a fern, and then to a leaf-bud. Gemmae are produced in a variety
of situations, as at the apex of a leaf and on the rhizoids.

The sexual organs of mosses are very commonly enveloped in closely
crowded leaves which have undergone a certain amount of modification,

FIG. 105. — «4, young plant of Barbula, in ', //, rhizoid,
producing protonemes /, and underground gemma k
( x 20). £, the same gemma ( x 300). (After Goebel.)

MUSCI

141

and the entire structure is sometimes — from analogy with the corre-
sponding structure in Flowering Plants— called the flower. Such a
flower may either be hermaphrodite, including both antherids and
archegones, or unisexual, and the species may then be monoecious or
dioecious. The female and the hermaphrodite flowers are not dissimilar
in appearance, while that of the male flowers is altogether different.

FIG. 106. — Fnnaria hygromettica ; longitudinal section through male inflorescence ; a, young an-
therid ; b, nearly mature antherid ; c, paraphyses ; d, e, perigonal leaves ( x 300). (After Goebel.)

In the hermaphrodite flowers the archegones usually occupy the
central position, corresponding to the pistil in Flowering Plants, the
antherids being arranged in an encircling spiral; while the whole is
enveloped in a rosette of small leaves termed the perichcete or perianth.
The entire structure resembles externally an elongated closed bud. Only a
single archegone in each flower is usually fertilised or arrives at maturity.
The female resemble the hermaphrodite flowers in every respect except

MUSC1NE&

srf that the antherids are suppressed. The male

fjr flowers present much greater variety in form

and appearance ; the male perianth or peri-
gone is usually composed of broader, shorter,
and thicker leaves, which sometimes sheath
at the base, and are not unfrequently red.
The flowers themselves are ovoid, globular,
or discoid; the antherids usually stand in
the axils of metamorphosed leaves. Both
male and female flowers are provided with
barren segmented filaments or paraphyses.
In the male flowers the paraphyses are fili-
form, club-shaped, or spathulate, and termi-
nate in several rows of cells ; in the female
flowers they are simple filiform bodies com-
posed of a single row of cells. Their function
appears to be to keep the archegones moist
until they have been fertilised by the anthe-
rozoids.

The first antherid appears to be a terminal
structure, being developed out of the apical
cell of a branch. An hermaphrodite flower
is probably derived from two independent
shoots, the female shoot being formed im-
mediately beneath the male organs. The
mature antherid is a stalked club-shaped, or
less often spherical sac, with a wall com-
posed of only a single layer of cells. In the
Sphagnacess it opens by longitudinal de-
hiscence ; in the other orders by an apical slit
through which the antherozoids, still enclosed
in their mother-cells, are discharged as a
thick mucilaginous mass, being imbedded in
a jelly which is expelled in jets when the an-
therid bursts, but which is soluble in water.
The antherozoids then escape from their
mother-cell walls, and swim about as filiform
bodies, furnished at the anterior end with
two slender vibratile cilia, and containing a
number of starchy granules. The male in-
poiyMck«m commune, florescence of Polytrichum exhibits a re-
uure plants with sporo- markable tendency to prolification (see fig.

male plant (nat. size). *

MUSCI

104). The archegone has somewhat the form of a very long-necked flask.
The wall of the venter or ventral portion, which is ovoid and supported
on a short stalk, consists of two layers of cells, while the elongated neck,
which is often somewhat twisted, is composed of from four to six rows
in a single layer. The interior of the venter consists of a single large
cell, the central cell, which divides into two by a horizontal septum ; the
lower segment contains the oosphere,
and the upper segment becomes the
ventral canal-cell, while the neck is
penetrated by a single axial row of

FIG. 108. — A, antherid of Funaria
hygrometrica, discharging anthe-
rozoids, a (x 350). B, antherp-
zoid of Polytrichum ; b, still
enclosed in mother-cell ; c, free
(x 800).

FIG. 109. — Fnnaria hygrometrica. A. longitudinal
section through female inflorescence; a, arche-

gones ; b, perichaetial leaves ( x 100). B, arche-
gone ( x 500) ; b, venter and central cell ; h, neck ;
tn, opening of canal. C, opening of neck (more
highly magnified), with stigmatic cells forced open.

cells which deliquesce into mucilage before impregnation. An open canal
is thus left, through which the antherozoids penetrate to the oosphere ;
the terminal stigmatic or lid-cells of each row of the neck, constituting
together the stigma, being forced apart by the exudation of the mucilage.
The first archegones are formed from apical cells of shoots.

144

MUSCINE&

The impregnated oosphere, or oosperm, develops into an embryo,
from which is derived the sporogone within the ventral portion of the
archegone. After investing itself with a cell-wall, it divides by a number
of longitudinal, radial, and transverse septa. At an early period in
typical mosses the young elongated sporogone ruptures transversely the
wall of the venter, the lower part of which forms a sheathing protection
to its base, and is termed the vagine, while the upper part becomes
elevated in the form of a cap or calypter. In the Sphagnaceae the sporo-
gone attains almost perfect development before the rupture of the

archegone ; in other mosses the
various portions of which the
sporange is composed are diffe-
rentiated only at a later date.
The sporange is at first filled
with fluid contents, the greater
part of which is the archespore,

FIG. no. — Funa.r:a hygrojnetrica. A, young
plant with young sporogone. B, mature plant
with mature sporogone ; s, seta ; f, sporange ;
c, calypter (natural size). C, longitudinal section
of sporange (greatly magnified) ; d. opercule ;
a, annulus ; /. peristome ; c, columel ; s, arche-
spore ; h, air-cavities. • (After Goebel.)

FIG. in. — Mouth of sporange of Fonti-
nalls antepyretica L., with peristome ;
afl, teeth ; z^, cilia ( X 50). (After
Schimper.)

developing into the mother-cells of the spores, from each of which are
produced four spores by free-cell formation after preliminary indica-
tion of bipartition. The withered neck of the archegone, which has
assumed a deep reddish brown colour, may often be recognised for
some time surmounting the apex of the calypter. The mature sporogone
consists of a pedicel or seta — which is usually of considerable length, the
lower portion or foot being enclosed withiri the vagine, but is short in
Sphagnum and some other genera — and the sporange or spore-capsule
surmounted by the calypter, while the base of the seta is surrounded by
the sheath-like vagine. The wall of the sporange is composed of several
layers of cells, the outermost of which has a distinctly epidermal cha-
racter, and is sometimes perforated by stomates with imperfect guard-cells.

MUSCI 145

While the greater part of the internal tissue is used up in the formation
of the spores, the axial portion always remains unchanged in the form
of a solid columel. There are no elaters. Leitgeb regards the sporogone
of all mosses (including Sphagnaceae) as consisting, in its earliest stage
of development, of an inner mass of cells, the etidothedvm, distinctly
separated from the peripheral mass, or amphithedum. In Sphagnaceae
the archespore is formed from the latter, in the other orders from the
former portion. Among the typical mosses he again distinguishes three
types, viz. : — (i) The Archidium-\.ypQ\ the spore-forming and sterile cells
are intermingled in the endothecium ; the spore-sac is separated from the
wall of the capsule by a bell-shaped cavity ; (2) the Andretza-type : the
endothecium is differentiated into the archespore and the columel, which
does not penetrate the former ; the innermost layer of the amphithecium
becomes the spore-sac, which is not separated from the wall of the
capsule by any cavity ; (3) the J?ryum-type : the endothecium is differ-
entiated as in the last case, but the columel penetrates the spore-sac,
which is separated from the wall of the capsule by a cylindrical cavity.
In all true mosses the sporogone is developed by means of a two-edged
apical cell. The ripe spores are roundish or cubical, with a thin, finely
granulated yellowish, brownish, or purple cuticularised exospore, and an
endospore of cellulose, and contain protoplasm, chlorophyll, and oil.
The number of spores in a capsule varies from sixteen (Archidium, Brid.)
to an immense quantity, and their size also varies inversely. Several
cases of hybridism have been recorded in mosses.

Mosses are found in all climates, from the coldest to the hottest ;
they are most abundant in temperate regions and in damp situations,
clothing old walls, the trunks of trees, £c. A few growT in stagnant, and
one genus (Fontinalis, L.) in running water. Some species are sapro-
phytes. They are of scarcely any economical value, but are of great
importance in nature in the formation of soil.

LITERATURE.

Bruch & Schimper— Bryologia Europrea, 1836-1865.
Schimper — Recherches anatom. et physiol. sur les Mousses, 1848.
Wilson— Bryologia Britannica, 1855.

Hofmeister— Pringsheim's Jahrb. wiss. Bot., 1863, p. 259.
Unger — Sitzber. Akad. Wiss. Wien, xliii., 1861, p. 497.
Lorentz — Moosstudien, 1864; Pringsheim's Jahrb. wiss. Bot., 1867, p. 363 ; Flora,

1867.

Berkeley— Handbook of British Mosses, 1863.
Leitgeb— Sitzber. Akad. Wiss. Wien, 1868, 1869.
Nageli — Pflanzenphys, Untersuch., Heft i. p. 75.
Janczewski— (Archegonium) Bot. Zeit, 1872, pp. 377 et seq.
Stahl— Bot. Zeit., 1876, p. 689.
Kienitz-Gerloff— (Sporange) Bot. Zeit., 1878, pp. 33 and 49.

L

146 MUSCINE&

Braithwaite— The British Moss-Flora, 1880-1887.

L'Abbe Hy— Bull. Soc. Bot. France, 1880, p. 106 ; Ann. Sc. Nat., xviii., 1884, P- IO5-

Goebel— Flora, 1882, p. 323.

Firtsch— Ber. Deutsch. Bot. Gesell., 1883, p. 83.

Satter— Ber. Deutsch. Bot. Gesell., 1884, p. 13.

Haberlandt — Ber. Deutsch. Bot. Gesell., 1883, p. 263 ; and Pringsheim's Jahrb. wiss>

Bot., 1886, p. 359.

Magdeburg — Die Laubmooskapsel als Assimilations-Organ, 1886.
Vaizey— (Sporogone) Ann. of Bot., i., 1887, p. 73.
Limpricht— Die Laubmoose, in Rabenhorst's Crypt.-Flora Dsutschland, 1885-1888.

The Musci are classified under four orders, as follows. The Sphag-
nacese exhibit much more important peculiarities than the other three
orders, and are ranked by some writers of authority as a distinct class.

ORDER i. — BRYACE^E.

This order includes the vast majority of the genera of mosses, and
all the more familiar forms except the bog-mosses. The sporanges or
' fruits ' form objects of great beauty in the autumn and winter, their
usual period of maturity, fertilisation taking place in the spring or early
summer. In some species the sporogone requires more than a year for
its full development. The sporogone consists of a sporange which is
always surmounted by a calypter, easily removed by the wind ; beneath
this is the opercule, which becomes detached, either alone qr together
with the annulus, a circular layer of hygrometric epidermal cells between
the opercule and the edge of the capsule; the whole elevated on a
longer or shorter stalk or seta, which is inserted at its lower end in the
vagine. The portion of the seta concealed in the vagine is known as
the foot, and acts as a kind of root, all the food-material needed for the
development of the sporogone being absorbed through it. The central
strand of tissue in the seta of the Polytrichacese consists, according to
Vaizey, of two portions — a leptophloem or rudimentary phloem, in which
the storing up and conduction of the food-material takes place ; and a
leptoxykm or rudimentary xylem, which serves for the conduction of the
transpiration-current to the lower portion of the sporange furnished
with stomates. In the Polytrichacese, in addition to the opercule, a
horizontal layer of cells termed the epiphragm remains attached to the
points of the teeth of which the peristome is composed, and covers the
mouth of the sporange after the removal of the opercule. The sporange
is penetrated by a complete axial columel. The spores are formed by
free-cell formation in fours within spore-mother-cells, themselves derived
from a single primordial layer, the archespore ; the walls of the spore-
mother-cells finally deliquesce, leaving the spores floating in a fluid

MUSCI

which for a time fills the spore-sac, composed of two or three layers of
barren cells immediately enclosing the mass of spores. Between the
spore-sac and the wall of the mature
sporange is an annular air-cavity, tra-
versed horizontally by rows of chloro-
phyllous cells, the trabecules. The
opercule is simply a piece of the epi-
derm of the sporange. In most genera
a portion of the wall of the sporange,
situated near the base of the columel,
consists of an assimilating system
composed of spongy or palisade-
parenchyme, containing chlorophyll,
and marked by the presence of sto-
mates. If the detachment of the oper-
cule leaves the mouth of the sporange
with a smooth edge, it is said to \yegym-
nostomous, as in Pottia (Ehrh.). More
often the mouth of the open sporange
is furnished with hair- or tooth-like
appendages, arranged in one or two
rows, constituting the peris tome. The
single row of these appendages, or the
outer row if there are two, are called
teeth, the inner row cilia. In some
genera the cilia are furnished with
lateral processes uniting them with one
another, or they are replaced by a
lattice-work of longitudinal or trans-
verse ridges termed the endostome. The
inner and outer layers of both teeth
and cilia differ from one another in
their hygroscopic capacity; hence, as
the moisture of the air varies, they
bend inwards and outwards, or some-
times coil spirally round one another
(Barbula, Hedw.). The peristome has a
very beautiful appearance under the
microscope, and its structure furnishes
useful characters for the discrimination
of the genera. In most genera the teeth and cilia are not composed of
cells, but of pieces of thickened cell-wall which become detached from a

L 2

FIG. 112. — A, longitudinal section of spo-
range of Polytrichum piliferum Schreb.
( x 15). B, transverse section ( x 5 '.. w, wail
of sporange ; cu, opercule ; c, columel ; p,
peristome ; ep, epiphragm ; a, annulus ;
z, air-spaces traversed by trabecules ; s,
spore-sac ; ap, apophyse ; st, seta. (After
Lantzius-Beninga.)

148

MUSCINE^E

layer of cells beneath the epiderm ; but in Polytrichum the teeth are
composed of bundles of thickened prosenchymatous cells. The exterior
peristome may have two distinct forms. Either the teeth have a double
outer and a single inner series of plates (Dipiokpida\ or the exterior
series is simple (Aplolep$Ue\ and then the inner series is nearly always
double. The Aplolepidae never have a double peristome ; and in the
Diplolepidae the inner peristome is occasionally wanting in particular
families or genera. In much the larger number of genera (Arthrodontecz)
the teeth are septated by transverse walls ; in a much smaller number

FIG. -L-L^.—Hypnumpopuleum S\v. (natural size).

7

FIG. 114. — Tetraphispelluclda.
Hedw. a (slightly magnified),
with open sporange ; b, ditto
with gemma ; c, sporange with
calypter (greatly magnified) ;
d, open sporange, showing
peristome.

Flo. 115. — Bryum argenteum L. FIG. •n.&.—Splachnum am-
(natural size). pullaceum L. (natural size).

{Nematodontetz) the transverse septa are wanting. The cilia, when
present, are usually shorter and less developed than the teeth ; they
are also composed of two layers of plates, often marked on the surface
by a beautiful network ; their divisions correspond to those of the teeth.
The number of both teeth and cilia is always a multiple of 4, the most
common numbers being 8, 16, 32, and 64. The most perfect type
of peristowie is seen in the Encalypteae, from which all the less perfect
forms are, according to Philibert, derived by degradation. In addition
to the presence of an epiphragm, the genus Polytrichum presents the
peculiarity, in most species, of the seta being swollen beneath the spo-
range, forming an annular cushion known as the apophyse (see fig. 112).

MUSCI

149

In most Bryaceae the tissue of the leaf is nearly homogeneous, with the
exception of the margin and an elementary midrib composed of elongated
prosenchymatous cells; but in Leucobryum (Hpe.) the small chloro-

FIG. 117. — Sporange of Polytrichum commune, showing
epiphragra. A, covered by calypter ; B, with calypter
removed ; C, with opercule removed (magnified).

FtG. 118.— Sporange of Hypnum
populeum, showing peristome
(magnified).

phyllous cells interlace among large empty cells with circular orifices in
their walls, as in Sphagnum.

The very numerous genera of Bryaceae are further classified as under.

Acrocarpi. — Fructification produced at the extremity of the branches.
Illustrative genera : — Weissia (Hedw.), Dicranum (Hedw.), Leucobryum
(Hpe.), Pottia (Ehrh.), Tortula
(Hedw.), Bartramia (Hedw.),
Encalypta (Schreb.), Fissidens
(Hedw.), Grimmia (Ehrh.), Or-
thotrichum (Hedw.), Zygodon
(H. & T.), Tetraphis (Hedw.),
Buxbaumia (Hall.), Polytri-
chum (Dill.), Aulacomnion
(Schw.), Bryum (H. & T.),
Mnium (B. £ S.), Funaria
(Schreb.), Splachnum (B. & S.), Tayloria (Hook.), Barbula (Hedw.),
Ceratodon (Brid.).

Pleurocarpi. — Fructification lateral, not at the extremity of the prin-
cipal branches. Illustrative genera : — Hedwigia (Ehrh.), Fontinalis (L.),
Hookeria (Sm.), Hypnum (Dill), Leucodon (Schw.), Neckera (Hedw.).

LITERATURE (in addition to the papers already quoted).

Philibert— (Peristome) Rev. Bryol., 1884-1888.

Vaizey— (Polytrichacese) Journ. Linn. Soc., xxiv. (1888), p. 162.

FIG. 119.— Peristome ot
A irichum undulalum
(magnified).

FIG. 120.— Peristome of
Cinclidium stygium
(magnified).

150

MUSCINE^E

ORDER 2. — PHASCACE^E.

In the small order of Phascaceae the roundish sporange dehisces
neither by the detachment of an opercule nor by longitudinal slits, but
decays to allow of the escape of the spores ; the calypter is ruptured
laterally without being raised up as a cap ; the columel is sometimes
wanting. According to Leitgeb,
Archidium (Brid.) resembles the
Hepaticse more closely than the
Bryacese in the processes which
lead to the formation of the
spores, especially in the differ-
entiation of the archespore into
spore-mother-cells which are

FIG. 121. — E^>hemerntm serratum Hampe ;
mature plant with persistent protoneme
(magnified). (After Luerssen.)

FIG. 122. — Pleuridium subulatum Rabenh.
sporange (magnified). (After Luerssen.

irregularly interspersed among cells that remain sterile. The spore-
mother-cells do not number more than from one to seven in each spo-
range ; in each of them four spores are formed tetrahedrally.

The Phascaceae are caespitose in their habit \ the protoneme persists
until the maturity of the sporogone. Principal genera : — Phascum (L.),
Archidium (Brid.), Ephemerum (Hpe.), Pleuridium (Brid.).

LITERATURE.

Leitgeb— Sitzber. Akad. Wiss. Wien, 1 880, p. 447.
Miiller — Pringsheim's Jahrb. wiss. Bot., 1867, p. 237.

ORDER 3. —

The Andreaeacese constitute a small order of mosses, comprising the
single genus Andreaea (Ehrh.), characterised by the absence of an oper-
cule to the sporange, which opens by four, or very rarely eight, longi-
tudinal slits, not reaching either to the base or the apex of the capsule.

MUSCI 151

The calypter is elevated, as in the Bryaceae, on the summit of the ripe
sporogone in the form of a cap ; there is a short seta buried in the vagine,
and the whole sporogone is elevated on a stalk or pseudopode, as in the
Sphagnaceae. At the base of
the sporange is an enlarged
apophyse. The structure of
the sporange differs from that of
the Bryaceae in the columel not
penetrating the archespore, and
in the absence of a cavity be-
tween the spore-sac and the
wail of the sporange. The con-
tents of the spore divide, while
still within the exospore, into
four or more cells. As in Sphag-
num, the oosphere is always
enveloped in a hyaline mass of
mucilage in which the anthero-
zoids imbed themselves.

The Andreaeaceae are also
caespitose in their habit, and are
natives of cold or mountainous
regions.

FIG. 124. — A. alpestris

Schmp. ; dehiscent spo-
range and apophyse
(magnified).

FIG. 123. — Andrecea
alpcstris Schmp.
(* 5)-

LITERATURE.

Kiihn— Entwickelungsgeschichte der Andreseaceen, 1870.

\Valdner-Bot. Zeit., 1879, p. 595; and Entwick. d. Sporogone v. Andresea, 1887.

ORDER 4. — SPHAGNACEAE.

The bog-mosses form a large portion of the vegetation of bogs and
swamps, and are characterised by the spongy structure of the whole
plant, the light yellowish green colour of the leaves, and the bright red
globular spore-capsules. The protoneme is much less developed than
in typical mosses ; and when the spore germinates on dry ground a
flat prothallinm intervenes between it and the leafy stem. The stem
branches abundantly, giving a caespitose appearance to the whole plant ;
and innovations, produced below the apex after the ripening of the
fructification, become detached by the decay of the lower part of the
stem, and carry on an independent existence. The leaves are lanceolate
and apiculate, usually arranged in a |- phyllotaxis, larger than in other
mosses, and of a peculiar structure of their own. As the leaf develops,

152

MUSCINE&

the single layer of cells of which it is composed becomes differentiated
into cells of two distinct kinds. A comparatively small number, of a

lozenge-shaped form, grow to a large
size and lose the whole of their con-
tents, while their walls are provided
with spiral thickening-bands, and fre-
quently display a large circular orifice
opening from one cell into the next.
A much larger number of cells remain
permanently of a very small size, are very
narrow in proportion to their length,
and, being filled with protoplasm and
chlorophyll, constitute the whole of the
nutritive tissue of the leaf. These
nutritive cells form a kind of network
ramifying among the large empty cells ;
but, as their total area is small com-
pared with these latter, the entire leaf
has, to the naked eye, a semi-trans-
parent very light yellow-green appear-
ance. The tissue of the stem consists
of cells of three distinct kinds. In
the centre is a cylinder of tfcin-walled
elongated colourless parenchymatous

FIG. 125.— Sphagnum acKtifoUitm Ehrh. . . , , . .

A, megaspore; B, microspore ; C, proto- Cells ; thlS IS enveloped in a layer Ol

dotted prosenchymatous cells, the walls

FIG. 126.— Flat prothallium ofS. acutifotium, with young leafy stems (x 120). (After Schimper.)

of which are thicker and of a brown colour ; while outside all is an
epidermal layer of large thin-walled empty cells, sometimes with spiral

MUSCI

153

thickenings and circular orifices, similar to those of the leaves. These
serve as capillary tubes, through which the water of the bogs in which
these mosses grow is raised, and the whole plant is in consequence
always saturated with water like a sponge.

FIG. 127.— A, portion of surface of leaf of 6". acntifolium. cl, small chlorophyllous cells ; f, large
empty cells ; /, orifices in these cells. B, transverse section (magnified).

FIG. 128. — Transverse section of stem of 6". cymbifolium Dill, x, inner cells with colourless wall ; r,
outer layer of cells ; ee, peripheral layers of cells with orifices, /(x 900). (Aft r Luerssen.)

154

MUSCINE^E

In their organs of reproduction, and especially in the structure of the
sporogone, the Sphagnaceae exhibit some divergences from the typical
mosses. Some species are dioecious, and the ' flowers ' of the monoecious
species are never hermaphrodite, the male and female organs being always
distributed on different branches. The male branches are distinguished
by their densely crowded leaves, which are often of a bright red colour,
giving a catkin-like appearance to the branch. On removing these the

antherids are found near the
middle of the branch. They
are minute nearly globular
or elliptical bodies, elevated
on a slender stalk, and
dehiscing by longitudinal
fission into valves. The an-
therozoids are spiral bodies
with many coils, and two
large flagellate cilia at the
posterior end. The arche-
gones are formed towards
the extremity of the female
branches, are accompanied
by paraphyses, and are
enveloped by peiuchaetial
leaves. They resemble in
all essential points those of
other mosses. On impreg-
nation the oosperm divides
by a horizontal septum into
two cells, the sporogone ori-
ginating from the upper cell
only. The nearly spherical
usually bright red sporange
differs from that of other
mosses in being completely
enclosed within the venter almost till maturity. It is, in most species,
elevated on a long slender pedicel, the pseudopode, which must not
be confounded morphologically with the seta of other mosses, being a
prolongation of the axis below the vagine. The lower portion of the
sporogone is widened out into a broad disc-like foot, resembling in
appearance the apophyse of Polytrichacese, which is seated on the top of
the pseudopode, and enclosed in the vagine. The calypter, when finally
ruptured, is not elevated in the form of a cap, but remains attached as a

FIG. 129. — ^". acutifolium. a, antheridial branches ; Z>,
leaves of primary stem ; ch, perichaetial leaves with
sporogones(x 5). (After Schimper.)

MUSCI

155

frill to the base of the sporange, which dehisces by a transverse slit near
the apex, detaching a strongly convex opercule. There is no peristome
nor annulus. A portion of the contents of the sporange remains un-
differentiated in the form of a low columel not reaching to the apex.
The remainder is converted into spores, which differ from those of other
mosses in being of two kinds, megaspores and microspores (see fig. 125).
According to Warnstorf (' Hedwigia,' 1886, p. 89 ; and ' Verhandl. Bot.

FIG. 130.— S. acutifolium. A, male branch,
with leaves removed to expose antherids,
a (magnified). B, antherid (more highly
magnified) dehiscing. C, antherozoid (still
more magnified). (After Schimper.)

FIG. 131.— A, S. acutifolium, section of female
inflorescence ; ar, archegones ; ch, pericha;tial
leaves. B, longitudinal section of sporogone, sg ;
ar, archegone ; c, calypter ; sg1, foot ; v, vagine ;
ps, pseudopode. C, S. squarrosum Pers. ; sg,
sporogone ; d, opercule ; c, ruptured calypter ;
gs, pseudopode ; ch, perichsetial leaves (magni-
fied). (After Schimper.)

Verein,' Brandenburg, 1886, p. 181), these two kinds of spore are found
either in the same or in different sporanges ; the diameter of the former
varies between 30 and 33 mm., that of the latter between 12 and 18 mm.
The megaspore is by far the most common form, and its germination only
has at present been observed. Warnstorf suggests that the two kinds are
sexually differentiated, the megaspores giving rise to a female, the micro-
spores toamaleprothallium, as in the Heterosporous Vascular Cryptogams.

156 MUSCINE^E

All the species of the single genus Sphagnum (L.) grow in bogs and
swamps, often covering enormous tracts of ground, and entering largely
into the composition of peat. The best authorities differ widely as
to the number of species ; the most divergent forms are distinguished
by well-marked characters, but these merge into one another by a com-
plete series of connecting links.

LITERATURE.

Schimper — Entwickelungsgeschichte der Torfmoose, 1858.

Waldner — Bot. Zeit., 1879, p. 595 ; and Entwickelung d. Sporogone v. Andreasa u.

Sphagnum, 1887.

Braithwaite — Sphagnaceae of Europe and North America, 1880.
Warnstorf— Die Europ. Torfmoose, 1881 ; and Flora, 1884.
Limpricht— Bot. Centralbl., x., 1882, p. 214.
Roll— Flora, 1886.

Class VIII.-Hepaticas.

The Hepaticae or Liverworts are small elegant plants, usually of a
bright green colour, which are especially abundant on damp ground or
rocks, or by the sides of streams ; a few species are aquatic. Some o'f
the genera bear a considerable external resemblance to lichens, others to
mosses. Their vegetative structure is either an undifferentiated thallus,
or consists of a distinctly differentiated stem and leaves, in both cases
attached to the soil by rhizoids. The former are known as the Thalloid
or Frondose, the latter as the Foliose Hepaticcz. The transition marks
the passage from the upper of the two great divisions of the vegetable
kingdom, the Cormophytes, to the lower division, or Thallophytes ; but
intermediate forms occur in the genera Fossombronia (Rad.) and Blasia
(Mich.). Even the foliose forms have no true vascular tissue, and no
true roots, the functions of which are performed by the rhizoids. Both
sections have, except in Riella (Mont.) and Haplomitrium (N. ab E.), a
distinct bilateral or dorsiventral structure ; the free side which faces the
light is differently organised from that which faces and often clings to the
substratum, and which is not exposed to light. The mode of branching
in the thalloid forms is dichotomous, and the growing region of the shoot
commonly lies in an apical depression formed by the more rapid growth
of the cells lying right and left of the apical cell, which has a form allied
to wedge-shaped. The filiform stem of the foliose forms, on the other
hand, ends in a bud with a more or less prominent cone of growth,
and the apical cell is a three-sided pyramid. The leaves of the foliose
forms always consist of only a single layer of cells, without even a rudi-
mentary midrib ; while the stem sometimes contains the first rudiments

HEPATIC^

157

of vascular bundles in the form of cambium-strings, and is furnished
with a slightly differentiated epidermal layer. In the thalloid forms the
thallus is composed of a more or less thick plate of tissue, which in
one order, the Marchantiacese, possesses on the upper side a strongly
developed epiderm, provided with stomates of very peculiar form, unlike
anything that occurs elsewhere in the vegetable kingdom.

The first result of the germination of the
spore is either a filiform protoneme, a flat plate
of cells, or a mass of tissue ; but the differentia-
tion of the protoneme from the sexual genera-
tion is not so well marked as in the Musci. The
non-sexual propagation of the Hepaticse takes
place either by innovation, i.e. by the continual
dying away of the stem behind, or by gemma,
which exhibit a high degree of development. In
the thalloid genera Marchantia (L.), Lunularia
(Mich.), and Blasia, these gemmae are found in
peculiar outgrowths of the upper surface of the
thallus known as cupuks, which are cup-shaped
in Marchantia (see fig. 150), crescent-shaped in
Lunularia, flask-shaped in Blasia. From the
base of these cupules there spring hair-like
papillae, the apical cells of which divide re-
peatedly in both directions, and constitute the
gemmae. In some of the foliose genera, e.g.
Madotheca (Dum.), the gemmae are formed out
of cells belonging to the margin of the leaf,
and simply detach themselves. Vochting states
that in Lunularia, and Marchantia also, isolated
masses of cells possess the power of regenera-
tion or development into new individuals, to
whatever part of the thallus they may have be-
longed. Shoots resembling a normal thallus
spring from the pedicel of the inflorescence of
Marchantia polymorpha (L.) when lying pros-
trate on the soil.

The locality of the sexual organs of reproduction, antherids and
archegones, varies in the different orders. In one genus, Anthoceros
(Mich.), they are endogenous, or originate in the tissue of the thallus
itself ; in the remaining thalloid forms they are produced on the upper
side of the thallus ; and in the Marchantiaceae on special vertical out-
growths, some of which bear antherids on their upper, others archegones

FIG. 132. — Jimgerinannia
nemorosa L. ( x 10).

158

MUSCINE&

on their under side ; these male and female inflorescences, as they are
termed, may be either monoecious or dioecious. In the foliose orders
there is a great variety in their locality and mode of origin.

The antherid originates as a
papilliform swelling of a super-
ficial cell, from which it is marked
off by a septum. When mature
it is seated on a pedicel or stalk,
and consists of an external layer
of cells containing chlorophyll,
which encloses the mother-cells of
the antherozoids. The antherid
dehisces by longitudinal fissures
into valves, and the mother-cells
themselves escape into the sur-
rounding moisture, into which
each discharges an antherozoid.
The antherozoids are slender
threads of protoplasm, with from
one to three spiral coils, and are
provided at the anterior end with
two long and very slender cilia, by
means of which they ' swarm ' in
the water with a rotating motion.
The archegone also first makes
its appearance as a papillose out-
growth of a superficial cell, which
then becomes separated in the
same manner. After this mother-
cell has divided several times
longitudinally, the central one of

FIG. 133. — Gottschea appendiculata N. ab E. (magnified).

the cells thus formed divides transversely into an upper stigmatic or
lid-cell and a lower cell. Two layers are subsequently formed, the
upper of which becomes the neck of the archegone, the lower its ventral

HE PA TIC ^ 159

portion, or venter. The lowermost cell of this ventral portion, now
known as the central cell, increases considerably in size, and divides
by a transverse septum into a lower and larger portion, which encloses
the oosphere, and an upper and smaller portion, the ventral canal-cell
In the meantime the upper layer of cells increases in length by the
formation of a number of fresh cells, the neck-canal-cells. The ventral
portion of the archegone becomes eventually enclosed in a wall, and by
the deliquescence of the neck-canal-cells an open channel is formed
down to the oosphere. In addition to the perichaste, the archegones
are frequently surrounded by a circular wall, originating as an out-
growth of the thallus, and known as the perigyne or involucre.

The result of the impregnation of the oosphere by one or more
antherozoids is the production of the embryo, from which is derived the
sporogone, which alone constitutes the sporophyte, or non-sexual genera-
tion. It is formed entirely from the ventral portion of the archegone.
Its external form and internal structure vary greatly in the different
groups ; as is also the case with the course of cell-divisions in its forma-
tion. Ultimately the wall of the spore-capsule becomes differentiated
from the archespore, or layer of tissue which develops into the mother-
cells of the spores and elaters when these latter organs are present.
There is usually no solid axis or columel. The cells which develop
into elaters cease early to divide transversely, and thus remain long,
while the rest of the cells round themselves off, and become mother-cells
of spores. The mature elaters (fig. 159) have in their wall an elongated
single or double spiral band, the twisting and untwisting of which on
the absorption and giving off of moisture helps to disseminate the
spores. Leclerc du Sablon finds the sporogone of the typical Hepa-
ticae to be composed, at a very early stage, of sixty-four cells, each of
which subsequently divides into four. These cells now elongate in the
direction of the axis of the sporogone, and then become differentiated
into two kinds. In the one kind the nucleus undergoes repeated
bipartitions, and these give rise to the spore-mother-cells ; in the other
kind the nucleus does not divide, and the protoplasm forms spiral
granulations ; these become the elaters. Rarely (as in Riella) they are
replaced by barren cells filled with food-material for the nutrition of
the growing spores. The two kinds of cell are equal in. number, each
alternating with the other. The degree of complexity of the sporogone
in the different orders of Hepaticse corresponds in the main to the degree
of development of the vegetative organs. In the Jungermanniaceas it
bursts longitudinally into four valves, and the walls are composed of two
layers of cells furnished with 'ornaments,' or elevated markings of various
patterns ; in the Anthoceroteaa it splits longitudinally into two valves ;

i6o MUSCINE^E

in the Ricciaceae and Marchantiaceae it bursts irregularly, and the wall
is composed of a single layer of cells without ornaments, or nearly so.
The spores also vary considerably in the different orders. In many
Jungermanniaceae the spore has only a single cuticularised membrane,
which is entirely used up in the formation of the germinating filament.
In most genera the wall is composed of two distinct separable layers,
the exospore and endospore ; while in Sphaerocarpus (Mich.), Corsinia
(Radd.), and some others there is a third outer layer, often beautifully
sculptured, which is derived from the membrane of the special mother-
cells of the spores. This layer is called by Leitgeb the perinium.
Warnstorf (Verhandl. Bot. Ver. Brandenburg, 1886, p. 181) finds in
Blyttia (Endl.) two kinds of spore, larger and smaller, which he believes
to produce female and male plants respectively. In Sphaerocarpus the
spores are combined into tetrads. When the spore germinates, the
endospore breaks through both exospore and perinium, when the latter
is present, and protrudes as the first rhizoid.

LITERATURE.

Bischoff— Nov. Act. Acad. Leop. Car., 1835.

Gottsche— Ibid., 1838.

Gottsche, Lindenberg u. Esenbeck — Synopsis Hepaticarum, 1844.

Kny — Pringsheim's Jahrb. wiss. Bot., 1865, p. 64.

Leitgeb— Bot. Zeit., 1871, p- 557, and 1872, p. 33 ; Mittheil. naturw. Ver. Steiermark,

1872; Unters. liber die Lebermoose, 1874-1881; and Ber. Deutsch. Bot. Gesell.,

1883, p. 246.

Janczewski — (Archegone) Bot. Zeit., 1872, p. 372 et set/.
Carrington— British Hepaticse, 1874.
Kenitz-Gerloff— Bot. Zeit., 1875, pp. 777 et seq.
Vochting — Pringsheim's Jahrb. wiss. Bot., 1885, p. 367.
Satter— Sitzber. Akad. Wiss. Wien, 1882.
Leclerc du Sablon— (Antherozoids) Comptes rendus, cvi., 1888, p. 876.

Liverworts are distributed throughout the entire globe, growing
mostly in moist situations. Many tropical species are epiphytic on the
leaves of Flowering Plants or ferns. They are of no economic importance.
They are classified under five orders, of which the first includes both
foliose and thalloid, the remaining four almost entirely thalloid, forms.

ORDER i. — JUNGERMANNIACE/E.

In this, much the largest order of the class, are included genera with
every variety of vegetative development, from an undifferentiated thallus
to a slender filiform stem, with sessile leaves seated either in two rows on
the upper side, or in three rows, two of them on the upper, and the third,
the amphigasters, smaller and adpressed to the under side. The thalloid

HEPATICsE

161

forms have, except in Haplomitrium, a bilateral structure resembling that
of the Marchantiaceae ; rhizoids and rudimentary foliar structures are
formed on the under, the sexual organs on the upper side. In the
foliose forms the leaves, always very small, are frequently bisected or
bilobed, the lower lobe or auricle being the smaller one, and amplexicaul
or concave. Goebel states that in Java many of the Jungermanniaceae
are epiphytic, and that in these the auricle is frequently hollowed out
into the shape of a pouch or pitcher, serving as a receptacle for water
(fig. 140). In some species of Physiotium (N. ab E.) this receptacle is
prolonged into the so-called 'tubular organ.' The leaves of the foliose

FIG. \^.—Fossombroniaptisilla^. ab E., male
plant, a, natural size ; b, magnified.

FIG. 134. — Calypogeia. Trichomanis
Cord, (magnified).

species consist of a single layer of cells without even the rudiments of
vascular bundles. There are species which form a connecting link
between the foliose and the thalloid Jungermanniaceae. The mode of
branching varies greatly, but growth always takes place by means of a
three-sided pyramidal apical cell.

As respects the sexual organs, some species are monoecious, others
dioecious. In the foliose genera they are usually formed at the apex of
the primary shoots or of special small fertile branches, which have often
an endogenous origin on the ventral side. These constitute the acro-
gynous section of the order, which includes all the foliose genera except
Haplomitrium. In the thalloid genera, or anacrogynous section, they

M

1 62

MUSCINE&

appear on the dorsal surface of the shoot, at some distance from the
apex ; while in the acrogynous forms they are formed in close proximity to
the apical cell. In Radula (Dum.) the entire female inflorescence, com-
posed of a number of archegones enclosed in
a perigyne, is developed from the apical cell
of a shoot, and from its youngest three
segments. Neither archegones nor antherids
are elevated on receptacles, as in the Mar-
chantiaceae. The antherids usually occur

FIG. i&.—Pellia epiphylla Cord.,
male plant, a, natural size ; b,
magnified.

FIG. 137. — Radula compla-
nata Dum. Plant with
closed and open sporange
(x 2).

FIG. 138. — Jtingermannia
barbata Schreb. Under
side of leaves with ciliated
amphigasters (magnified).

singly or in groups in the axils of the leaves. In Pellia (Radd.) the an-
therids are imbedded in the thallus, the archegones appearing in large
numbers at the apex of the shoot. In the Geocalyceae (e.g. Calypogeia,
Radd.) the female branches are so hcllovred out that the archegones are

IT.

FIG. 139. — I. Under side of stem of Fnillania
Tatnarisci Dum. , with true leaves and amphi-
gasters (magnified). II. Leaf of F. dilatata
(more magnified).

FIG. 140. — Auricle of Fritllania, sp. (mag-
nified). (After Goebel.)

sunk in a deep pitcher-shaped hollow or tube, within which the spo-
rogone is subsequently formed. In other genera they are concealed by
the nearest leaves. The modified leaves which thus enclose a group of
archegones, or of both archegones and antherids, constitute the perichcete,

HEPATIC.Z

163

each archegone being, in addition, usually surrounded by a distinct mem-
branous envelope, the perianth or perigyne.

In the formation of the sporogone, the fertilised oosphere first divides
by a wall at right angles to the axis of the archegone. Only the upper
of the two cells thus formed — that is, the one that faces the neck of the
archegone — undergoes further divisions ; it becomes the apical cell of
the sporogone, and sometimes again divides transversely once or twice
before a longitudinal wall makes its appearance in it ; the two cells thus
formed finally divide into four apical cells arranged as octants of a hemi-
sphere. The basal portion of the growing archegone swells out and
penetrates down into the tissue of the stem, forming the vagine.

a/

n

FIG. 141. — Sexual organs of Radnla
complanata. ar, archegone ; an, an-
therid ; b, leaf. (After Hofmeibter.)

FIG. 142. — Jungermann:a bicuspidata. L. Longi-
tudinal section of immature sporogone, sg ; ar,
calypter ; ar1 , unfertilised archegones ; /, base of
perigyne ; st, stem ; 6, leaf. (After Hofmeister.)

After frequent divisions have taken place, the wall of the spore-capsule
becomes differentiated from the inner tissue, out of which are developed
the spores and elaters. There is no columel. By rapid extension of
the hitherto short pedicel, the calypter is ruptured at the apex, and the
globular sporogone, containing the already ripe spores, becomes elevated.
The inner of the two layers of which the wall of the sporogone is com-
posed has become absorbed before the ripening of the spores ; the single
layer of cells which still remains is ruptured at the apex, and splits into
four (rarely more) longitudinal valves, which separate suddenly in the
form of a star, carrying with them at the same time the elaters, and thus
bringing about the dispersion of the spores. The mature elaters are

M 2

1 64

MUSCfNEJS,

long fusiform thin-walled cells, marked internally by from one to three
brown spiral bands, but more complicated in structure in the foliose
than in the thalloid genera.

Illustrative genera. — Foliose : Radula (Dum.), Jungermannia (L.),
Lejeunia (G. & L.), Frullania (Radd.), Madotheca (Dum.), Mastigo-
bryum (N. ab E.), Calypogeia (Radd.), Lepidozia (Dum.), Plagiochila
(Dum.), Geocalyx (N. ab E.), Chiloscyphos (Cord.), Gymnomitrium
(N. ab E.), Lophocolea (Dum.). Thalloid'. Metzgeria (Cord.), Aneura
(Dum.), Fossombronia (Radd.), Pellia (Radd.), Blasia (Mich.).

LITERATURE.

Leitgeb — Bot. Zeit., 1871, p. 556 ; and Abhandl. Bot. Ver. Brandenburg, 1880, p. 58.

Gottsche — Abhandl. Gesell. Naturf. Hamburg, 1880, p. 39.

Goebel — (Epiphytic Species) Ann. Jard. Bot. Buitenzorg, vi., 1887, p. 21.

ORDER 2.— MONOCLEACE^:.

This small order appears to occupy an intermediate position be-
tween the Jungermanniaceae and the Anthoceroteae. The vegetative
structure is either thalloid or foliose. The elongated sporange dehisces
longitudinally, and contains elaters, but has no columel.

Principal genus : — Monoclea (Hook.).

FIG. 144. — Anthoceros Iwis
male plant (natural size).

FIG. 143.— Monoclea Forsteri Hook, (magnified).

FIG. 145. — A. lewis, a, dehiscent sporange
(x 2).

ORDER 3. — ANTHOCEROTEAE.

The vegetative structure consists of a flat ribbon-like thallus, the
irregular dichotomous ramifications of which form a circular disc
composed of one or more layers of cells, each cell containing only a

HEPATIC^E 165

single chlorophyll-corpuscle. The antherids and archegones arise
endogenously on the upper side of the thallus, apparently without any
definite arrangement, and are not protected by a perigyne. The mature
sporogone is an elongated dehiscent two-valved pod, provided with
stomates, which forces its way through a mass of tissue overarching the
archegone, and is known as the involucre. Within the sporange is, in most
genera, a solid axial columel\ the wall consists of four or five layers of
cells ; the rest of the contents, developed from the archespore, becoming
the mother-cells of the spores and elaters. Except in some species of
Arithoceros (L.) the elaters are of simpler structure than in the other
Hepaticae, having no spiral bands. Anthoceros possesses peculiar
cavities on the under side of the thallus, opening by slits or fissures,
which are regarded by some authors as stomates, by others as mucilage-
receptacles. Filaments of Nostoc, which have found their way into
these cavities through the slits, cause peculiar changes in them, and
have been mistaken for endogenous gemmae. The genus Anthoceros is
of much interest from the fact that the sporophyte-generation shows a
greater vegetative energy than is usually the case with Muscineae;
growth continues at the base of the sporange, and new spores are formed
there after those at the apical portion are already mature.
Principal genus : — Anthoceros (L.).

LITERATURE.
Leitgeb — Die Anthoceroteen, 1879.

ORDER 4. — RICCIACE^E.

The Ricciaceae are regarded by Leitgeb as forming a connecting link
between the Jungermanniaceae and the Marchantiaceae ; but in some re-
spects they are simpler in their structure than either of these orders. The
thallus is usually flat, and branches dichotomously ; it floats on water or
roots in the soil. In Riella (Mont.) it is submerged and erect, and has
the appearance of a ring forming a continuous spiral round an axial stem.
It is always destitute of stomates, but is provided with internal air-
cavities, and with rudimentary foliar organs among the rhizoids. The
antherids and archegones are not, as in the Anthoceroteae, endogenous,
but are developed from young superficial cells of the upper surface,
which grow into papillae and become overarched, in the course of their
development, by the surrounding tissue. Both antherids and archegones
are enclosed in an involucre formed in this way; the antherids are
sessile, the involucre sometimes constituting an elevated neck above
them. In Riccia (L.) the archegones are ultimately buried in the

1 66

MUSCINE&

thallus ; while in Oxymitra (Bisch.) they are raised above the surface.

The sporange is a thin-walled spherical capsule, occasionally produced
under water, entirely filled with spores without
true elaters br columel, and, with its calypter,
depressed in the thallus. It is much less differ-
entiated in its structure than in the other
orders. In all the genera except Riccia and
Oxymitra the elaters are represented by sterile
cells among the spore-mother-cells. The spo-
range bursts irregularly when ripe, but the
spores are only set free by the decay of the

FIG. 147. — Sp'i(erocarpus terrestfis Sm. Frond and archegone
(magnified).

FIG. 146. — Riella helicophyila
Mont, (magnified)

FIG. 148. — Riccia glarica L. A, section of apical region of
frond, ar, archegone ; c, oosphere ( x 50). £, immature
sporogone, sg ; ar, neck of archegone ( x 300). (After Hof-
meister.)

surrounding tissue of the thallus. The spores of Sphaerocarpus (Mich.)
and Corsinia (Radd.) have a beautifully sculptured extine. Riella is
altogether dioecious, and perfects its fructification beneath the water.

Principal genera : — Riccia (L.), Duriaea (Bor.), Oxymitra (Bisch.),
Riella (Mont.), Sphaerocarpus (Mich.), Corsinia (Radd.).

LITERATURE.

Kny— Pringsheim's Jahrb. wiss. Bot., 1866, p. 364.
Leitgeb — Die Riccieen, 1879.

...

HEP A TIC^E

167

ORDER 5. — MARCHANTIACE^E.

The thallus is flat and ribbon-shaped, and usually branches dicho-
tomously from two apical cells ; it is frequently furnished with a well-

FIG. 149. — MarcJtantia polymorpha L. Male
plant (natural size).

-•

FIG. 151. — M. polymorpha. Female inflo-
rescence (magnified).

FIG. 150. — M. polymorpha. Male inflorescence FIG. 152. — Fegatclla conica Cord. Male plant
and cupule (magnified). (natural size).

marked midrib, and is coriaceous in texture. It is composed of three
distinct layers of cells, viz.: — (i) the air-chamber-layer to which the

168

MUSCINE^E

stomates belong; (2) a close tissue containing but little chlorophyll, and
with the cell-walls pitted or reticulately thickened, without intercellular
spaces but sometimes containing mucilage-receptacles j and (3) a ventral

rlil

FIG. 153. — A, transverse section through middle portion of thallus of M. polymorpha (x 30); B,
through marginal portion (more highly magnified). /, colourless layer without intercellular spaces
•&,. epiderm of upper side ; chl, chlorophyllous layer ; sp, stomate ; s, partition-walls between air-
chambers ; .«, lower epiderm ; h, rhizoids , b, leaf-like lamellae. (After Goebtl.)

FIG. 154. — Portion of young receptacle of M. polymorpha. A, vertical section; a, epiderm; sfi,
stomate ; S, partition-wall separating air-chamber from chlorophyllous cells ; g, mucilage-cell. B,
C, young stomate ; po, pore. (After Goebel.)

epidermal layer, from which spring rhizoids and leaf-like lamellae. The
mucilage-passages are especially developed in Fegatella (Radd.) and

HEPATIC^E

169

Preissia (Cord.), and the thallus of the latter genus has also rudimentary
vascular bundles. The stomates which penetrate the epidermal layer of
the upper surface of the thallus into the air-chamber-layer are of a struc-

FIG. 155.—^, B, C, young shoot of M.

morpha (slightly magnified) with cupules ;
. iru, apical region. D, portion of epiderm

(more highly magnified), sp, stomate.

FIG. 156. — Female inflorescence of M, poly-
inorpha seen from the under side, sr, radiat-
ing branches ; f, sporogone. (After Goebel.)

ture quite peculiar to this order. Each stomate is formed, according to
Leitgeb, by the simple separation of four or more superficial cells, and the
subsequent segmentation of these in a direction parallel to the surface.

FIG. 157. — A, male plant of M. polymorpha. B, longitudinal section through inflorescence, ha
o, o, openings to antheridial cavities, a. C, nearly ripe antherid. D, two antherozoids (x 800).
(After Goebel.)

They are situated in the centre of plates of a rhombic form, consisting
of portions of the epidermal layer which overarch large air-cavities.
From the base and sides of these air-cavities spring chlorophyllous cells

MUSCINE^E

in rows directed upwards, but not actually reaching the epidermal layer
of cells through which the stomates penetrate ; while beneath them is
the non-chlorophyllous layer, consisting of cells longest in the hori-
zontal direction without intercellular spaces. Each stomate has a number
_,__ of guard-cells formed by

radial cell-divisions. The
details in the structure of
the stomates differ in the
different genera. Leitgeb
describes them as of two
kinds, simple and canali-
culate. The former are
epidermal pores situated
immediately above the air-
chambers ; the latter, which
occur in Marchantia and
Preissia, have the ap-
pearance of canals exca-
vated in the surface of the
thallus. Some of the rhi-
zoids of Marchantia are
characterised by singular
internal thickenings to the
cell-wall. The peculiar non-
sexual organs of propagation
of Marchantia, Lunularia
(Mich.), and other genera,
known as cupules, have
already been described (figs.
150,155). A peculiar non-
sexual mode of propagation
by means of gemmae occurs

FIG. 158.— Development of archegone of M. polymorpha. in Fegatella (Radd.).
(x 300). I—V, before, VI— VIII, after fertilisation, e,
central cell with oosphere ;f, young embryo ; si, lowest cell
of axile row ; //, perigyne. IX, immature sporogone in

venter of archegone ( x 30) ; a, neck of archegone ; st,
stalk of sporange which contains young spores and elaters.
( After Goebel.)

The sexual reproductive
organs of the Marchanti-
aceaa are, in most of the
genera, borne on erect
branches of the thallus of a peculiar umbrella-like form, which have been
variously termed receptacles, discs, and inflorescences. They may be male,
female, or bisexual ; and, when unisexual, the species may be monoecious
or dioecious. In Fegatella the male inflorescences are oval discs sessile
upon the thallus (fig. 152). The inflorescence is generally regarded

HEP A TIC^E

171

as a transformed thalloid axis. The antherids spring from superficial
cells of these branches which are depressed in hollows on the upper
surface of the disc, and become overarched by the surrounding tissue.
With the exception of one section, the Targionieae, in which they occur
at the apex of ordinary shoots, the archegones are borne on the under
surface of the female discs, which are always stalked, while the male
discs may be either stalked or sessile. The archegones are variously
surrounded by involucres or perigynes. Leitgeb describes the sexual
organs as being at first distributed over the surface of the thallus,
and becoming subsequently collected into
groups or inflorescences, which have at
first a dorsal position, but become con-
stantly pushed towards the apex. The
mature sporange is usually shortly stalked,
and contains elaters, which radiate from
the centre towards the circumference. It
has no central columel. It either dehisces
at the apex with numerous teeth, or is
four-lobed, or the upper portion becomes
detached by an annular fissure as an
opercule. The elater.s are well developed,
and are furnished with several spiral bands,
but do not usually appear to take any
part in the expulsion of the spores from the
sporange.

The thallus of many Marchantiaceae
displays remarkable hygroscopic properties,
which have their seat in the 'mechanical'

layer, i.e. the layer of closely packed cells FIG. 159.— A, piece of eiater of M.
containing but little chlorophyll, which
underlies the air-containing assimilating
layer. On desiccation this layer contracts

greatly, so that the epidermal layer with its stomates is completely pro-
tected from further evaporation by the recurved ventral surface covered
with brown or violet scales. In this condition the dried -up thallus may
retain its vitality for a very long period. The cells of the mechanical
layer are frequently occupied by colonies of Nostoc.

Illustrative genera : — Marchantia (L.), Targionia (L.), Fegatella
(Radd.), Reboulia (Radd.), Fimbriaria (N. ab E.), Dumortiera (N. ab
E.), Plagiochasma (L. & L.), Preissia (Cord.), Lunularia (Mich.).

polymorpha (magnified). A ', a por-
tion more highly magnified. B,
pitted cell of thallus. C, D, rhizoids
with internal thickenings.

172 MUSCINE^E

LITERATURE.

Mirbel — Mem. Acad. Sc., xii., 1835.

Strasburger — Pringsheim's Jahrb. wiss. Bot., 1870, p. 409.

Vogt — Bot. Zeit., 1879, pp. 729 and 745.

Goebel— Arb. Bot. Inst. Wiirzburg, 1880, p. 529.

Leitgeb — Sitzber. Akad. Wiss. Wien, 1880, pp. 40 and 123; and Die Marchantieen,

1881.

Prescher— (Mucilage-receptacles) Sitzber. Akad. Wiss. Wien, 1882.
Mattirolo — (Hygroscopic Properties) Malpighia, ii. 1888, p. 181.

FOSSIL MUSCINE^:.

No remains have been found earlier than the Tertiary formations
which appear to belong to Muscineae. Here and in the Quaternary
beds remains or impressions occur which have been referred to various
families of Musci and Hepaticae, including leaves of a single species of
Sphagnum and a single moss- capsule. The leaves of Jungermanniaceae
are not uncommonly found enclosed in amber.

173

THIRD SUBDIVISION AND CLASS IX.
CHARACE^.

THE true position of this small group in a natural system of classifi-
cation has been a subject of much controversy. By some writers of
high authority it is regarded as occupying the highest place among
green Algae. On the other hand, although without any lignification of
their tissue, the Characese display, in the structure of their vegetative
organs, a distinctly higher type of structure than the Thallophytes, in the
distinct differentiation of the plant into a primary axis or stem, and
secondary axes or branches ; but the branches are similar in structure
to the primary stem. They are, in fact, Cormophytes rather than
Thallophytes ; and it seems best to retain them as a distinct subdivision
intermediate between the Muscineae and the highest Algae.

The plant is acrogenous, growing by means of an apical cell contained
in an apical bud ; the main stem has indefinite apical growth, the branches
increasing by definite apical growth. The branches and the organs of
sexual reproduction grow in the axils of other lateral organs of more
simple structure, which are usually termed leaves; those that subtend
the reproductive organs being by some writers described as bracts or
bracteoles. In all the Characeae these appendicular organs spring in
whorls from well-defined nodes of the primary stem, imparting the pecu-
liar habit to the plants by which they are distinguished from nearly
all other Cryptogams. Each internode consists, in the Nitelleae, of a
single very large cell extending along its whole length, and many times
longer than broad. In the majority of the Chareae this internodal cell
is invested by a layer of similar elongated cells of much smaller diameter
arranged spirally round it, collectively known as the cortex, and giving
the stem the appearance of being spirally striated. Each node consists,
in the corticated species, of a single layer or plate of small cells from
which the cortex is derived. From the nodes spring the whorls of
branches and their subtending leaves. The branches are altogether
similar in structure to the primary axis. The leaves have also, in the
Chareae, a simple cortical layer, with the exception of the apex, where

174

CHARACE/E

the large terminal cell is exposed. In addition to the leaves there
spring, from the basal nodes of some species of Chara (L.), other leaf-
like structures known as stipules, one, two, or three in connection with
each leaf. The stipular cells are always undivided
by septa, and arise as papillae on the cortical
cells.

The cortex of the stem and branches is de-
veloped out of the nodal plate of cells ; the
upward and downward prolongations from the
nodes usually meeting about the middle of each
internode, where they dovetail into one another.
These cortical internodal cells do not, however,
like the axial cells, remain entire ; they divide,
both transversely and longitudinally, into three
parallel rows of cells, the central row of each
series being somewhat elevated into a ridge.
The mode and extent of development of the
cortical cells vary according to the species.
The number of leaves in a whorl
is usually from four to ten. At
the lower part of the main stem
the internodes are shorter, and
from the nodes spring rhizoids
or rooting filaments which serve
to fix the plant in the soil, con-
sisting of long hyaline nearly undi-
vided tubes, which grow obliquely
downwards, and lengthen only at

their apex. The rhizoids are
always trichomic, springing from
superficial cells.

The nearly hemispherical
apical cell of the terminal bud of
the stem first divides by a trans-
verse wall into a new apical cell
and a disc-shaped segment-cell.
Each segment then again divides
by a wall parallel to the first;
the lowest of these does not again divide, but develops into the axial
internodal cell, while the upper one undergoes vertical division, and be-
comes a node. Each successive whorl on the main stem alternates with
those immediately above and below it, so that the oldest leaves of a

FIG. 160. — Chara fragilis
Desv. (natural size).

nified)L> (mag'

CHARACE^E 175

whorl, which subtend the branches, are arranged in a spiral line running
round the stem ; but this is not the case with the branches or secondary
axes, where the members of contiguous whorls are superposed.

The Characeas exhibit in an especially clear and beautiful manner
the phenomenon of cydosis, or rotation of the protoplasm (see fig. 163).
The best objects for observation are the large internodal cells of Nitella
(Ag.), the apical cells in the leaves of Chara, or some of those belonging
to the reproductive organs, especially to the ' manubria.' The cell first of
all develops vacuoles in its protoplasm, which coalesce into a single

A

FIG. 162. — Longitudinal section through bud of C.fragilis, showing apical cell, /, and segments, g, b.
A , cells empty. B, with cell-contents, granular protoplasm, chlorophyll-grains, and vacuoles. C,
with cell-contents contracted by iodine ( x 500). (After Sachs.)

large sap-cavity. The outermost thin parietal layer of protoplasm, in
which are imbedded most of the grains of chlorophyll, remains motion-
less; within this motionless lining is a thick layer of protoplasm, in which a
regular current gradually sets up, up one side of the cell and down the other;
the boundary between the two currents being marked by hyaline bands
entirely destitute of chlorophyll, the neutral zones, in which no movement
is visible. The direction of the rotating movement in each cell stands
in a definite relation to that of all the other cells of the plant. From
time to time the movement ceases, and then begins again in the oppo-
site direction. Before the rotation commences the cell-nucleus has

usually broken up into a number of fragments. The current is most
rapid next to the stationary parietal layer, and becomes gradually slower
towards the interior. As the cell grows the rotating protoplasm becomes
differentiated into a watery and a less watery denser portion, the former
having the appearance of a hyaline cell-sap, in which the latter floats in
the form of larger or smaller roundish lumps. Since these denser bodies
are passively swept along by the clear rotating protoplasm, the appear-
ance is presented as if the cell-sap caused the rotation. Together with
the denser lumps of protoplasm of less regular form, there are also a
number of globular masses carried along in the current, which are
covered with delicate protoplasmic spines or cilia; their nature and
function are involved in obscurity.

Owing to the large size of the cells and the distinct differentiation of
the nucleus, the internodal cells of the main axis of Chara and Nitella,
as well as the apical cells of the leaves, have been largely used for fol-
lowing the complicated processes connected with cell-division and the
division of the nucleus. Schmitz describes the process as one of 'direct
division of the nucleus,' Treub and Strasburger as one of 'fragmenta-
tion ; ' Johow differs in some respects from all previous observers ;
Cagnieul (Bull. Soc. Bot. France, 1884, p. 211) finds the process espe-
cially easy to follow in the mother-cells of the antherozoids. Schaar-
schmidt (Bot. Centralblatt, vol. xxii., 1885, p. i) describes peculiar cell-
wall thickenings and grains of 'cellulin' in Chara hispida (L.).

The Characeae do not produce spores, i.e. single non -sexual pro-
pagative cells ; but are multiplied non-sexually in three different ways,
the nodes being always the place of origin of the propagative cells,
(i) Chiefly in Lychnothamnus stelliger (A.Br.), but also in C. hispida,
C. aspera (Willd.), and Lamprothamnus alopecuroides (A.Br.), structures
called bulbils or 'amylum-stars' are formed, agglomerations of cells deve-
loped round the larger internodal cells at the level of the nodes ; they are
of beautiful regularity, and are densely filled with starch and other food-
materials. On germinating they appear to produce at first other bulbils,
and from these a new plant. (2) Chara fragilis and other species produce,
on old hibernating or on cut nodes, in the axils of the leaves, peculiar
branches known as gymnopodal shoots, which differ from the ordinary
branches in the partial or entire absence of the cortex in the lowest
internode and in the first whorl of leaves. The cortical branches which
descend from the first node become detached, bend upwards, and pro-
pagate themselves. (3) Also on C. fragilis, Pringsheim describes the
occurrence of 'pro-embryonic,' or more properly of prothalloid branches.
These also spring from the nodes of the main axis, but differ essentially
from the ordinary branches, presenting a similar structure to the pro-

CHAR AC E^

177

thallium or * pro-embryo ' which proceeds from the germinating oosperm.
No mode of vegetative propagation is known in the other genera.

The sexual reproductive organs of the Characeae, the male antherids
and the female archegones, are visible to the naked eye as minute orange -
red globes and elliptical green bodies springing from the nodes in the
axils of leaves or bracts.
The antherids are glo-
bular bodies, of a bright
red colour when mature,
from ^ to i mm. in dia-
meter, morphologically
the terminal cell of a
leaf or lateral leaflet.
The moderately thick
wall of the antherid is
made up of eight flat
disc-shaped cells called
shields, four of which,
situated round the distal
pole of the ball, are tri-
angular, while the four
situated round the base
are four-sided. On their
inner face there lies
a layer of chlorophyll-
grains, which eventually
turn red, while the outer
face is clear and trans-
parent ; the walls of
these cells are folded in-
wards at the edge where
they meet. From the
centre of the inner face
of each shield a cylin-
drical cell, termed a
handle or manubrium,
projects inwards nearly to the centre of the globe. The antherid
is supported on a short flask-shaped pedicel-cell, which also projects
into the interior between the four lower four-sided shields. At the
free end of each of the eight manubria is a roundish hyaline cell, the
head-cell or capitulum. These twenty-five cells—viz, the eight shields,
eight manubria, eight capitula, and the pedicel-cell — constitute the

FIG. 163.— Nitella flexilis Ag. A, nearly ripe antherid sub-
tended by two bracts showing direction of protoplasm-currents,
and neutral zone, i. 2>, manubrium, with capitulum, secondary
capitula, and whip-like filaments. C—F, antheridial filaments,
showing formation of antherozoids. G, antherozoids (C — G x
550). (After Sachs.)

178

CHARACE&

framewoik of the antherid. Each capitulum bears six smaller cells,
or secondary capitula ; and from each of these grow four long whip-
shaped filaments, bent into a number of coils and filling up the interior
of the globe. The manubrium, capitulum, secondary capitula, and
whip-shaped filaments, bear a resemblance to a many-thonged whip.
The number of these filaments in an antherid amounts to nearly 200,
and each filament is divided by transverse septa into from 100 to 200
small disc-shaped cells. The protoplasm in each of these antheridial
cells becomes gradually transformed into an antherozoid strongly re-
sembling the corresponding organ in Muscineae rather than in Thallo-

FIG. 164.— A, portion of branch otC.JragfZis', a, antherid ; 6", archegone; c, crown ; /3', /3", bracts
(x 50). B, a young antherid ; SK, young archegone (x 350). 'After Sachs.)

phytes. It is a slender thread of protoplasm coiled spirally like a cork-
screw, somewhat thickened at rhe posterior end, and bearing at its
pointed anterior end two long fine cilia. The number of antherozoids
in an antherid is, as will be seen, from 20,000 to 40,000. When ripe,
the eight shields fall apart, and the antherozoids escape from their
mother-cells, and move about rapidly in the water by means of their
vibratile cilia. This appears generally to take place in the morning, the
antherozoids swarming about for some hours till the evening.

CHARACE&

179

The Characese are either monoecious or dioecious. In the former
case the male and female organs are formed in close juxtaposition on the
same node, the archegone being somewhat below the antherid in Nitella,
above it or by its side in Chara. The archegones, like the antherids, are
metamorphosed leaves. When ready for fertilisation, the archegone has
a longer or shorter ovoid form, and is borne on a short pedicel-cell. In
the interior is an axial row of cells enveloped by five tubes, which are at
first straight, but are afterwards coiled spirally round the axial row.
The lowest portion of each of these tubes is an elongated unsegmented
cell; while at the upper part
one or two very small cells are
segmented off. In Nitella each
of the terminal cells again di-
viides into two by a vertical
septum. The five terminal cells
of Chara and the ten terminal
cells of Nitella are not twisted,
and form together the crown.
When the archegone is ready
for impregnation these crown-
cells separate from one another,
forming the neck, and leaving an
open passage down to the axial
row. This apical cavity is, how-
ever, very nearly closed below
by a diaphragm formed by the
projecting inwards of the five
neck-cells, through which there
is only a very narrow opening
for the entrance of the anther-
ozoids. The apical cell of the
axial row is much larger than
the rest, and is the female or
germ-cell, corresponding to the
central cell in the archegone

of the higher Cryptogams. It is filled with protoplasm, oil-drops, and
starch-grains ; its apical portion, the apical papilla, or receptive spot,
containing only hyaline protoplasm. Between the apical cell and the
pedicel-cell of the archegone, there is in Chara only a single cell, in
Nitella a group of cells, the ' Wendungszellen.' Before fertilisation the
crown is a compact structure covering the apical cavity ; but when the
archegone is ready for impregnation a small aperture is formed in its

FIG. 165.— A, fertile branch ot Nitella. flexilis
(natural size) ; /, internode ; b, branches. B, upper
portion of fertile leaf, b ; K, node ; nb, bracts ; S,
young archegone. C, older leaf with two bracts ;
a, antherid ; 6", spermocarp. D, half-mature sper-
mocarp (highly magnified). (After Sachs.)

i8o

CHARACE&

centre, through which the antherozoids force their way, and finally enter
the apical cell by the deliquescence of the upper portion of its cell-wall,,
and coalesce with the apical papilla. The whole contents of the apical
cell may be regarded as the oosphere.

Impregnation causes at first very little external change in the structure
of the female organ. The protoplasm of the oosphere, now invested
with a cell-wall and transformed into an oosperm, gives place to starchy
or oily matter; the walls of the enveloping tubes which lie next it in-
crease in thickness and hardness, and the oosperm thus becomes invested
in a hard black shell or pericarp. The structure thus formed, the so-
called ' fruit ' or spermocarp of the Characeae ultimately becomes de-
tached, falls into the mud at the bottom of the water, and there germinates
in the next spring.

When the spermocarp germinates, the oosperm first divides into

FIG. 167.— Calcareous
spermocarp of C.
hispida (magnified).

FIG. 166. — A-D, stages in development of archegone of AT. flexilis. 6, apex
of fertile leaf; x, ' Wendungszellen ; ' K, crown (x 300). (After Sachs.)

three cells, a large basal and two apical cells, the former apparently
serving the purpose of supplying with nutriment the young plant which
proceeds from the latter ; and these three cells may be said together to
constitute the embryo. From one of the two apical cells proceeds a long
hyaline unseptated filament, commonly called the primary root, by means
of which the young plant is attached to the soil. The other of the two
apical cells develops into a hypha-like filament, consisting at first of a
single row of cells with limited apical growth, and called by some writers
the 'pro-embryo,' or more correctly the prothallium. In this prothallium
are developed two primary nodes at considerable distance from one
another, and separated by a very long internode. From the lower of
these two primary nodes there springs a whorl of rhizoids, which soon

CHARACEjE

181

usurp the functions of the primary root. The upper of the two nodes

is still at some distance from the apex of the prothallium, this apical

portion above the upper node consisting of a few much shorter cells.

From this upper node is developed the new

plant. It is divided by longitudinal septa into

two inner and six or eight peripheral cells. The

peripheral cells ultimately become rudimentary

leaves, which do not, however, form a true whorl.

In the midst of them appears a bud, or growing

point, developed from one of the inner cells, from

which springs the new stem, in a direction nearly

at right angles to that of the prothallium. At

present the formation of the prothallium has been

observed only in the genus Chara.

A remarkable instance of parthenogenesis has
been recorded in Chara crinita (Wallr.). The
species is dioecious, and male plants are extremely
rare. On the female plants the oospheres develop
into oosperms without apparently any possibility of
their having been impregnated ; and the spermo-
carps thus formed germinate in the ordinary way.

The Characese consist of only a compara-
tively small number of species, but some of them
very abundant, growing submerged in deep or in
shallow, in stagnant or in running, or occasionally
in brackish water. Several species are grown with
great facility in fresh- water aquaria, where they
multiply very rapidly. The presence of certain
species may be detected by the foetid odour of
sulphuretted hydrogen given off when decaying.
Phipson (Compt. Rend., Ixxxiv., 1879, pp. 316,
1078) attributes this odour to the presence of a
special substance which he calls charadn. The
typical genus Chara is distinguished by its power
of extracting calcium carbonate from the water in
which it grows, the whole plant becoming thus
covered with a calcareous incrustation, which
frequently renders it difficult to make out the
structure. Hence the family has acquired the popular names of ' brittle -
worts' and 'stoneworts.' Nitella translucens (Ag.) sometimes forms
enormous mat-like masses at the bottom of ponds.

The systematic position of the Characeae has been a matter of much

FIG.

. — Germination of C.
fragilis. sp, spermocarp ;
•zv', first root ; z", first inter-
node of prothallium ; d,
first node ; w", rhizpids i
q, second elongated inter-
node of prothallium ; g;
second' node with first whorl
of leaves ; pi, apical por-
tion of prothallium ( x 4).
(After Pringsheim.)

1 82 CHAR ACE ^

controversy. In habit and in general appearance they resemble the Algae,
among which they are placed by the majority of writers. But in some
important points of structure they differ so widely from all known families
of Algae, that a true estimate of their relationships appears to require their
location in a distinct subdivision by themselves. With the exception
of the Fucaceae and the Conjugate, the Characeae stand alone among
the larger groups of Cryptogams in the entire absence of true spores.
Seeing that the oosperm germinates directly in the soil, the embryo which
results from its first divisions developing directly into the new plant,
there is no 'alternation of generations ' in any accurate sense of the
term. From those classes where , a true alternation of generations
attains its fullest development, the Muscineae and Vascular Cryptogams,
the Characeae differ in the complete suppression of the sporophyte-
generation ; while Phanerogams (at all events those Angiosperms which
are destitute of endosperm) deviate, on the other hand, in the suppres-
sion of the oophyte-generation. In the investment of the oosperm with
a lignified pericarp directly without any previous breaking up into
carpospores, the Characeae again differ essentially from all classes of
Algae.

The Characeae are divided into two orders, viz. —

1. CHARES. — Stem and branches usually corticated and calcareous;
leaves usually with one or two stipules at their base ; antherids usually
solitary on each node; crown always five-celled; pericarp often cal-
careous. Genera : Chara (L.), Lamprothamnus (A. Br.), Lychnothamnus
(Leon.).

2. NITELLE^E. — Stem and branches not corticated nor calcareous;
leaves without stipules ; archegones often clustered ; crown always ten-
celled ; pericarp not calcareous. Genera : Nitella (Ag.), Tolypella
(A. Br.).

LITERATURE.

Goppert and Cohn — Bot. Zeit., 1849, pp. 665 et sec].

Braun — Monber. Berlin Akad. Wiss., 1852, p. 220 ; and 1853, p. 45 ; and (Partheno-
genesis) Abhandl. Berl. Akad. Wiss., 1856, p. 337.

Thuret— Ann. Sc. Nat., xvi., 1851, p. 18.

Montagne— Ann. Sc. Nat., xviii., 1852, p. 65.

Nageli— Beitrage zur wiss. Bot., ii. , 1860, p. 61.

Pringsheim— Jahrb. wiss. Bot, 1863, p. 294.

Braun — Conspectus systematicus Characearum europrearum, 1867 ; and Abhandl.
Berlin Akad. Wiss., 1882.

De Bary — Monber. Berlin Akad. Wiss., 1871, p. 227 ; and Bot. Zeit., 1875, pp. 377
et seq.

Bennett— Journ. of Bot., 1878, p. 202.

Groves — Journ. of Bot., 1880, p. 97.

C HA RACEME 183

Miiller— Bull. Soc. Bot. Geneve, 1881.
Johow— Bot. Zeit., 1881, pp. 729 et seq.
Nordstedt -Hedwigia, 1888, p. 181.
Allen— Characece of America, 1888.

FOSSIL CHARACE^:.

In various strata, commencing with the Cretaceous, remains known
as gyroliths are found, sometimes in great abundance, which appear to
be the petrified pericarp of the spermocarp of Characeae. Upwards of
forty species have been described, some of them closely resembling
existing forms.

184 ALG^E

FOURTH SUBDIVISION.
ALGsE.

THE degree of affinity between the small group of Characeae and the
very large group of Algae is, as has already been mentioned, a point
on which the best authorities are not agreed. But, in passing from
one to the other, we finally cross the line which separates the Cormo-
phytes from the Thallophytes. From this point we have to do exclu-
sively with plants whose vegetative organs are in no sense differentiated
into axial and appendicular, and which further contain no true vessels
and no woody tissue. On their lower limit there is no sharp line of
demarcation between the Algae and the chlorophyllous Protophyta, but
the consideration of Algae as a group by themselves, distinct from Fungi,
we regard not only as convenient, but as also most in accordance with
their probable affinities.

Within the limits above mentioned, the degree of complexity in the
structure of Algae is very various, and the different types will be best
described under the separate families. In their vegetative structure we
may recognise three types : the elaboration in the development of a
single cell, the loose association of cells into a family or coenobe, and the
close aggregation of cells into a filament or a thallus. To the latter
belong all the higher families, and in some of these we see indications
of the various kinds of tissue found in vascular plants. The higher
forms, consisting of a well-developed thallus of large size, in which the
cells are associated with one another in all three directions, are almost
exclusively marine, and include the whole of the organisms popularly
known as seaweeds. In the larger forms the plant is attached to the
substratum — a rock, stone, or other large alga — by a root-like organ of
attachment known as the disc. The attachment is, however, always
superficial, and the organ takes no part in the absorption of nourish-
ment for the plant. The organ may result from the repeated division of
a single cell, or it may be more complicated, being formed out of the
termination of the downward growth of cortical rows of cells. In nearly
all fresh-water Algae the single cell, the coenobe, or the filament is en-

185

closed in a more or less strongly developed gelatinous sheath. The
greater number of families exhibit both a sexual and a non-sexual mode
of reproduction, though in some cases one or the other mode has not
yet been detected. In the great majority of families the non-sexual
propagating bodies are motile cells or zoospores, minute masses of proto-
plasm formed singly from the whole contents of a cell by rejuvenescence,
or more often in large numbers by free-cell formation, destitute of a true
cellulose membrane, but containing protoplasm and a contractile
vacuole, and provided with two or sometimes a larger number (rarely
only one) of vibratile cilia, by means of which they move about actively
for a time, then come to rest, excrete a cellulose membrane, and de-
velop into a new plant. In one class only, the Florideae, are the zoo-
spores replaced by non-motile tetraspores ; in the Conjugate and
Fucaceae they are altogether wanting. The simplest form of sexual
reproduction is that of conjugation, or the coalescence of two compara-
tively undifferentiated masses of protoplasm. These masses of proto-
plasm may be either the contents of stationary cells, which are nearly
or quite alike, as in the Conjugates, or they may be motile ciliated
bodies indistinguishable from zoospores — zoogametes — or they may be
distinguished from the true zoospores by their smaller size. From
the conjugation of zoogametes there is a gradual transition through
intermediate stages to a true sexual process, the impregnation of a
stationary oosphere by a motile antherozoid, usually much smaller than
the oosphere, the result being the production of an oosperm by the
encysting of the oosphere in a coat of cellulose. In the higher families
the oospheres and antherozoids are formed in special cells or organs,
known as oogones and antherids respectively. In the Florideae the
process displays very great complication ; the structure in which the
oosphere is formed is known as the carpogone ; the fertilised oosphere is
the carposperm, which often breaks up into carpospores. In this class
also the antherozoids are replaced by motionless protoplasmic bodies
known as pollino ids. Multiplication by the simple fission of individuals,
by the detachment of gemmce, or buds, and by the encysting of special
cells or masses of cells into cysts, also occur. In the green Algae
(Confervoideae heterogamae and isogamae and Conjugates) single non-
motile cells which become detached for the purpose of propagation are
termed by Wille akinetes when they are formed without rejuvenescence,
aplanospores when formed by rejuvenescence. The former occur in
Trentepohlia (Mart.), Conferva (L.), and Ulothrix (Ktz.), as well as in the
Nostocaceas and Rivulariaceas, the latter in the Confervaceae. The two
kinds pass into one another, and akinetes into vegetative cells, by in-
sensible gradations.

1 86 ALG^E

Any classification of Algae which attempts to follow the lines of
affinity — in other words, any natural system of classification — must be
based on a consideration of both the vegetative and the reproductive
organs. All the families of Algae appear undoubtedly to have sprung
from the PROTOCOCCOIDE^E, and their further development has taken
place in three directions — the perfection and differentiation of the in-
dividual cell, the association of cells into ccenobes, and cell-division.
The production of ccenobes may be supposed to start from such forms
as Botryococcus among Protocoaacece. ; the first step in the develop-
ment of the CCENOBI^E being the Sorastrece, including Sorastrum,
Ccelastrum, and Selenastrum, motile colonies of non-ciliated cells, with
no known production of zoospores. The series attains a much higher
development in the PandorinecR, including Pandorina, Gonium, and
Stephanosphaera, where reproduction is effected by the conjugation of
zoogametes. Simple organisms like Chlamydomonas and Chlamydo-
coccus, consisting merely of conjugating zoogametes, are possibly retro-
gressions from the higher forms, though they may also be stages in a
direct ascent from Protococcus. Eudorina, with a rudimentary differ-
entiation of antherozoids and oospheres, unquestionably indicates the
line of development of Volvox^ in which this differentiation is more
strongly developed. In Volvox we have the culmination of the attempt
of nature to evolve higher organisms out of coenobes. Hydrodictyon is
probably an aberrant member of this group, and the Pediastrece are more
or less nearly related to them.

From the Eremobice, the fuller development of the individual cell has
advanced a further stage in the MULTINUCLEATVE, composed of the
Siphonodadacece and Siphonetz, and characterised by each individual
consisting of an enormously developed cell, often ramifying greatly and
attaining gigantic dimensions, and possessing several, often a very con-
siderable number, of nuclei. In the Siphonocladaceae the only known
mode of reproduction is by the conjugation of zoogametes ; and
Botrydium displays a distinct affinity with Botrydina among the
Eremobice. The Siphoneae or Cceloblastae, represented by Vaucheria,
are a higher development of the same series, in which true sexual organs,
oogones and antherids, are formed in addition to non-sexual zoospores ;
and in this genus culminates the striving after a higher development in
the elaboration of a single cell.

A rudimentary cell-division is exhibited in the Nostochinea among
Protophytes, but accompanied by other conditions which prevented its
full success there. Where cell-division originated in the Protococcoideae
is not clear, probably in the Eremobiae ; we find it already fully developed
in the CONFERVOIDE^ ISOGAM/E, the members of which consist of a

ALG^E 187

single unbranched or branched filament of cells, the only known modes
of multiplication being the conjugation of zoogametes and the direct ger-
mination of larger zoospores. In the lowest two classes, the Chroolepidece
and Ulotrichacece^ embracing a very small number of genera, the filament
is usually unbranched ; in the two higher, the Confervacecz and Pitho-
phoracecB, further vegetative activity is displayed in the copious branching :
and in the former we have an indication of affinity with the Multi-
nucleatae in an occasional plurality of nuclei.

The exact course of evolution from the isogamous Confervoideae is
obscure, but it would appear to have taken place in three distinct lines.
The first of these, which evidently came to an abrupt conclusion, is the
CONJUGATE, consisting of the Zygnemacece, Mesocarpece, and Desmidiece^
a well-marked and sharply differentiated group with no near affinities.
The first two orders, consisting of unbranched filamentous forms, are
probably derived directly from the Confervoideae, although the change
in the mode of reproduction is very abrupt. The production of zoospores
is entirely suppressed, and they are reproduced solely by the conjuga-
tion of cells belonging to the same or to different individuals. The
Desmidieae must then be regarded as a group adapted, by a certain
amount of retrogression in both vegetative and reproductive characters,
to life in shallow water ; and derived, through such filamentous genera
as Desmidium and Hyalotheca, from Zygnemaceae with lateral con-
jugation. By some writers the Diatomaceae are associated with the
Desmidieae ; our reasons for placing them among the Protophyta will
be given hereafter. The mode of reproduction by conjugation attains
its climax in the Mesocarpeae.

The second line of descent is that of the brown seaweeds. In the
PtLEOSPORE^E we have every shade of transition in the mode of repro-
duction from isogamous to heterogamous. The typical Phaeosporeae,
such as Punctaria and Ectocarpus, are characterised by the possession of
two kinds of zoosporange, unilocular and multilocular. The zoospores
produced in these two kinds of zoosporange present no difference in size
or form ; but those from the unilocular sporanges appear in all cases to
germinate directly, while those produced in the multilocular sporanges
are sometimes zoogametes with sexual functions. In some families one
or the other kind of zoosporange is suppressed. In the Ectocarpacecz and
some other genera we have a mode of reproduction closely resembling
that in the isogamous Confervoideae, except in the greater differentiation
of the cells which become zoosporanges, a conjugation of zoogametes
which are to all appearance exactly alike, though a slight differentiation
is exhibited in the fact of one of them coming to rest and partially losing
its cilia before conjugation takes place. In the Cutleriacea the differ-

i88

entiation is more complete ; the male and female swarm-cells are pro-
duced either on the same or on different individuals ; the female are
much larger than the male, and come perfectly to rest, entirely losing
their cilia before being impregnated by the former. In the Dictyotacece
the differentiation is carried still further, and the female reproductive
bodies are from the first motionless oospheres not provided with cilia.
Several families of Phaeosporeae exhibit reduction or degradation of the
vegetative structure ; and among these we are disposed to place the
small group of Syngeneticce, consisting of but two genera, Hydrurus and
Chromophyton, which resemble one another in but few points except
the possession of a brown endochrome. In the former genus the pro-
pagative bodies are reduced to non-ciliated masses of brown protoplasm,
which germinate directly without impregnation ; in the latter the vegeta-
tive structure is almost entirely suppressed ; the propagative bodies are
uniciliated masses of protoplasm of two kinds, but without any observed
process of conjugation. The step from the Dictyotaceae to the FUCACE^E
is an easy one. In the highest type of brown seaweeds, such as Fucus or
Durvillasa, with their typical heterogamous or * oogamous ' reproduction,
consisting in the impregnation of a comparatively large oosphere by a
number of minute antherozoids, we have the highest attainment of this
series of development.

The third line of descent from isogamous Confervoideae is a much
more direct one, to the CONFERVOIDEAE HETEROGAM.E, including the
three orders Sphceropleacece, CEdogoniacecE, and Coleoch&tacece. In the
first of these, which comprises only a single species, we have a distinct
differentiation of the male and female reproductive cells, the latter having
now become permanently quiescent ; but still a strong reminiscence of
the Confervaceae in the multinucleated cells. The CEdogoniaceae
exhibit a distinct advance in vegetative structure, and still more in the
cells which contain the male and female reproductive bodies being, for
the first time in this series, differentiated into antherids and oogones
respectively. Between the (Edogoniaceoe and the Coleochaetaceae we
have an evident connecting link in Bulbochsete ; but the typical genus
Coleochaete presents a singular reduction of the non-reproductive portion
of the thallus from a filament to a single plate of cells. The mode of
sexual reproduction has now attained a much higher degree of complexity.
The oogone is surmounted by a tubular appendage, the trichogyne,
through which the motile antherozoids find their wa.y to the oosphere
in order to impregnate it. The fertilised carpogone, as it is now called,
then becomes invested by a cortical layer of ceils, forming the complex
body known as the sporocarp.

The Coleochaetaceae lead up .directly to the highest type of structure
attained by Algae, the FLORIDE^E or red seaweeds, a well-defined and

ALG& 1 89

natural group, though exhibiting remarkable variety in the degree of
development of the sexual organs. So striking is the resemblance in
the mode of impregnation in the most highly developed genera of
Florideae, such as Callithamnion, Dudresnaya, or Corallina, to that in
Coleochaete, that it is scarcely possible to doubt the direct descent of
one from the other ; the chief difference is in the replacement of motile
antherozoids by pollinoids which have no active power of motion. The
process of fertilisation is the most intricate which occurs among Thallo-
phytes, and presents a remarkable forecast, so to speak, of the mode
afterwards elaborated in Flowering Plants, though only after a very long
interval, comprising the entire evolution of the Muscineae and Vascular
Cryptogams. With the loss of motility of the male reproductive cells
is also correlated a corresponding loss of motility of the non-sexual
reproductive cells or tetraspores. In the higher families of the Florideae
we have also the highest development of the organs of assimilation found
among Thallophytes. If the view is correct that the higher Florideae
are derived directly from the Coleochaetaceae, it follows that we must
regard all the less highly developed families of this group as retrogres-
sions from the parent type ; and this view appears to offer the most
probable explanation of the true position of some aberrant forms. In
the Helminthodadiacetz and Squamariacece the degeneration is exhibited
solely in the less perfect development of their thallus or vegetative
structure. In the Lemaneacect this is accompanied also by a simpler
structure of the sexual organs. But here, as well as in Batrachospermum,
we have the first rudimentary appearance of a phenomenon resembling
that known as ' alternation of generations,' which plays so important a
part in the Vascular Cryptogams, and which may possibly indicate the
genesis of the Muscineae. In the Porphyracetz we find a reduction of the
thallus to a simple filament or plate of cells, accompanied by only a rudi-
mentary development of both carpogones and trichogynes, and a limited
reversion to motility in the tetraspores. Regarding the Porphyraceae^
as exhibiting retrogression from the more complicated Florideae, rather
than as the lowest member of an ascending series, it is difficult to resist
the conclusion that the Ulvacece are derived from the Porphyraceae by
further retrogression, displayed in the entire suppression of antherids and
oogones, and a reversion to the primitive conjugation of zoogametes.
In their vegetative structure the Ulvaceae differ widely from the isogamous
Confervoideae, with which they are usually associated, while the close
resemblance between Ulva and Porphyra is obvious. In the Florideae:
the Algae attain their highest type of development.

By far the larger number of Algae grow entirely immersed in water,,
running or stagnant, fresh, brackish, :or salt ; some float on the surface
without any attachment • others are found on moist soil, among moss*

190 ALG&

&c. The whole of the marine vegetation of the globe, with the excep-
tion of a very small number of species of Flowering Plants, belongs
either to the Algae or to the chlorophyllous Protophytes. They vary in
size from the microscopic Desmidieae and Pediastreae to that of shrubs
or trees in the case especially of some genera of Laminariaceae and
Fucaceae ; and in these classes, as well as in the Florideae, we find a
rudimentary differentiation, not only of tissues, but of organs, which
leads the way to the much more complete development in the higher
classes of the vegetable kingdom. Fresh- water Algae are, with very few
exceptions (species of Bangia, Hildenbrandtia, Lithoderma, Hydrurus,
&c.), green. Among marine Algae there are many genera of green sea-
weeds, belonging chiefly to the families Confervaceae, Siphonocladaceae,
and Ulvaceae ; but these mostly grow in shallow water. As regards all
organisms growing in deep seas, it appears to be essential to them that
the green colour of the chorophyll should be masked by a coloured
pigment, red in the case of the Florideae, brown in those of the
Phaeosporeae and Fucaceae ; the nature of these pigments will be dis-
cussed under the separate families. A few of the smaller species,
belonging to the Coleochaetaceae, Chordariaceae, and Squamariaceae,
grow attached to stones, larger Algae, or other marine objects, as flat
discs, gelatinous cushions, or calcareous incrustations, and the deposition
of lime takes place to a much larger extent in the corallines. The propor-
tion of ash to the organic constituents is much larger in marine than in
land or fresh-water plants, seaweeds having the power of extracting from
the salt water large quantities of the soluble salts contained in it. The
larger species of Fucaceae and Laminariaceae are largely used in the
north of Europe for manuring the land and for foddering cattle ; and in
former times the manufacture from their ashes of kelp and barilla was
an important industry. They are also an important commercial source
of iodine. From the quantity of gelatine contained in their thallus,
some species of Ulvaceae, Porphyraceae, Fucaceae, and Laminariaceae are
also occasionally used as articles of food or for medicinal purposes.

LITERATURE.

Greville — Algae, in Scottish Cryptogamic Flora, 1823-28; Algae Britannicae, 1830.
Kiitzing — Phycologia generalis, 1843 ; Tabulae Phycologicae, 1845-69 ; and Species

Algarum, 1849.
Harvey — Phycologia Britannica, 1846-51 ; Nereis Australia, 1847-49 ; British Marine

Algae, 1 849; Nereis Boreali- Americana, 1851-58; Phycologia Australica, 1858-63.
Hassall — British Fresh-water Algae, 1845.
Nageli — Die neuern Algensysteme, 1847.
Agardh— Species, Genera, et Ordines Algarum, 1848-80 ; Till Algernes Systematik,

1872-87.
Thuret — Antheridies cles Cryptogames, 1851.; Zoospores des Algues, 1851 ; and

Etudes Phycologiques, 1878.

ALG.-E 191

Landsborough -Popular Hist, of British Seaweeds, 1851.

Pringsheim -Ueber Befruchtung u. Keimung der Algen, 1855.

Gray — British Seaweeds, 1867.

Wood — Fresh-water Algae of North America, 1873.

Bornet & Thuret— Notes Algologiques, 1876 80.

Falkenberg — Die Algen, in Schenk's Handbuch der Botanik, vol. ii., 1881.

Hauck — Die Meeresalgen, in Rabenhorst'sKryptogamen-Flora Deutschland, 1883-85.

Schmitz — Die Chromatophoren der Algen, 1882; andjourn. Micr. Soc. , 1883, p. 405.

Cooke — British Fresh-water Algae, 1884.

Gay— Bull. Soc. Bot. France, 1886, Sess. Extraord., p. 21.

Bennett -Journ. Linn. Soc., xxiv., 1887, p. 49.

Wolle — Fresh-water Algae of the United States, 1887.

Wille — (Resting-spores) Pringsheim's Jahrb. wiss. Bot., 1887, p. 492.

Stroemfelt— (Attachment-disc) Bot. Centralbl., xxxiii., 1888, pp. 381 & 395.

Class X.--Florideae.

This large family — known also as Rhodosporeae and Rhodospermese
— exhibits the highest type among Algae in the mode of sexual repro-
duction, and also possibly in the development of the vegetative organs.
It consists almost entirely of seaweeds, including all the red and purple
kinds. A few species only, belonging to the genera Hildenbrandtia
(Nard.), Batrachospermum (Bory), Lemanea (Bory), Bangia (Lyng.),
and a few others, grow in fresh water. Some of these are green, but the
great majority of the Florideae are of a bright red colour, varying with
purple, brown, yellowish, or dirty white. The 'fronds' do not attain
nearly the size of those of the Fucaceae and Laminariaceae, but they are
often of delicate texture and finely divided, rendering them the most
beautiful of our seaweeds.

The thallus varies within very wide limits in its degree of develop-
ment. In a few genera, such as Callithamnion (Lyng.), it consists of
distinct filaments of cells which are almost always branched ; in others,
as Porphyra (Ag.), Hildenbrandtia, and Cruoria (Fr.), of a flat plate of
cells, composed of only a single or of several layers ; in the fresh- water
genus Batrachospermum, of an axis with beautifully regular whorls of
branches ; while in most seaweeds it constitutes a massive parenchyme,
or the filaments are held together by a more or less dense gelatinous
envelope. Growth takes place, in the majority of cases, by means of a
single apical cell, but this is often followed by a strong intercalary
growth. The apical cell is not three-sided, as in Vascular Cryptogams,
but is either wedge-shaped, dividing by walls which incline alternately to
the right and left, or it divides by nearly parallel walls. In some forms,
however, especially the prostrate Melobesiaceae and Squamariaceae, and

192

ALG.-E

in the Nemalieae, the apical cell appears to be replaced by a group of equi-
valent cells. Wille distinguishes six types of Florideae as respects their
mode of growth ; in four of these groups growth takes place from a
single apical cell ; in two from an apical mass of cells, with peripheral

growth. In the so-called
polysiphonous seaweeds,,
such as Polysiphonia
(Grev.), a transverse sec-
tion of the ' frond ' shows
a large central elongated
cell, surrounded by four
or more smaller cells,
which are also elon-
gated in the longitudi-
nal direction, and which
are known as siphons.
These pericentral tubes
are often connected with
one another and with
the axial cell by threads
of protoplasm. When
the pericentral tubes are
wanting the frond is
monosiphonous. In some
genera belonging to the
Ceramiaceae either the
single axial tube or both
axial and pericentral
tubes are surrounded by
a pseudo-cortex formed
of a dense agglo-
meration of secondary
branches originating at
the nodes and closely
adpressed to the pri-
mary branch. These
• are always the result of
further division of the
pericentral tubes, the
apical cell remaining
undivided. In other genera a similar cortical tissue is composed of
moniliform rows of cells arranged at right angles to the axis.

Although there is in the Florideae no distinct differentiation of the

FIG. 169. — Gigartina mamillosa Ag., with cystocarps
(natural size). (After Luerssen.)

FLORIDE^E

193

tissue into epidermal, assi-
milating, and conducting
systems, still there are, in
the higher forms, cells which
are especially concerned
with assimilation, and which
may be either isodiame-
.trical. or elongated in either
direction. Such assimilat-
ing tracts are classed by
Wille under three heads,
^viz. : — (i) those which act
.also for purposes of con-
ducting ; (2) those which
are altogether distinct from
the conducting cells ; and
(3) those where, in addition
to an assimilating, there are
also primary and secondary
conducting cells. In some
species the 'frond' assumes
the appearance of a stalked
leaf, as in Hydrolapathum
(Rupr.) and Delesseria
(Grev.), often of the most
beautiful form, and present-
ing even a rudimentary
venation. The genera
Melobesia (Lmx.), Hilden-
brandtia, Cruoria, and some
others, consist of small
algae, mostly marine, with
crustaceous or gelatinous
thallus, growing flat on
stones or larger algae, often
of lichen-like appearance.
In their mode of growth
some Florideae display bi-
lateral symmetry, and the
branching may be either
monopodial or sympodial.
In Polysiphonia, Spyridia

FIG. 170. — Polysiphonia. opaca Zan. «, with cystocarpxs ;
b, with tetrasporanges (natural size) ; c, branch with
tetrasporanges ; d, branch with cystocarp ( x 100).
(After Kiitzing.)

194

ALG.-E

(Harv.), and some others, the 'phyllotaxis' is spiral. The genera Ryti-
phlcea (Ag.), Vidalia (Lmx.), Amansia (Lmx.), and Polyzonia (Suhr)
are distinguished by the endogenous formation of the normal lateral
shoots. In Pollexfenia (Harv.) and allied genera, Falkenberg records a
remarkable congenital union of all the branches of the thallus which lie
in the same plane.

The red colouring matter of the Florideae has been investigated
by Rosanoff, Cramer, Askenasy, Sorby, and others.
Cramer first extracted it, from Bornetia secundiflora
(Ag.) and Callithamnion caudatum (Ag.), in the form
of regular crystals, partly hexagonal, partly octohedral,
and gave it the name rhodospermin. Rosanoff ex-
tracted it by cold fresh water, and found it carmine-
red in transmitted, reddish yellow, or rarely green,
in reflected light. It is insoluble in alcohol. The
chlorophyll-grains also exhibit fluorescence when left
behind, if the pigment, the phyco-erythrin of Askenasy
and Sorby, has escaped from them in consequence of
injury to the plant. The spectrum of the chloro-
phyll is nearly identical with that in Flowering Plants.
The compound pigment of the red Algae is termed
by Schiitt rhodophyll, the term phyco-erythrin being
limited to the portion soluble in water, while the
portion soluble in alcohol he calls Flo-
ridece-green. Cohn found, in Bornetia
(Thur.), colourless crystalloids of an albu-
minous substance coloured a beautiful
red by the same pigment; and Klein
has found similar crystalloids in several
Florideae. The chromatophores contain
starch-grains, which differ both from
the ordinary grains of Flowering Plants
and from those of the brown Algae jn
being coloured brown or red by iodine.
Schmitz (Sitzber. Niederrhein. Gesell.,

1880) has detected a number of nuclei in the vegetative cells of many
Florideae, but not in the reproductive cells. Hick (Proc. Brit. Ass., 1883;
' Nature,' vol. xxix., 1884, p. 581), Massee (l.c.\ and Moore (Journ. Linn.
Soc. Bot., vol. xxi., 1886, p. 595) find continuity of protoplasm from cell
to cell very beautifully displayed in Callithamnion (Lyng.), Ptilota (Ag.),
Polysiphonia, and several other genera, not only in the vegetative cells,
but also in the tetrasporanges. In Corallina (L.), Melobesia, Liagora

FIG. 171. — Hydrolapathum. sangui-
neum Stackh. a, two young fronds
with two cystocarps ; l>, c, prolifica-
tions from the stem (natural size).
(After Kiitzing.)

FLORIDE&

195

(Lmx.), and a few other genera, the 'frond' becomes densely incrusted
by a deposit of calcium carbonate, giving to the so-called 'coralline's'
the external form and appearance of miniature corals.

The ordinary non-sexual propagative organs of the Florideae are
bright red motionless spores, commonly formed in fours in the mother-
cell, and hence known as tetraspores (the sphaerospores of Agardh), and
the cell in which they are produced as a tetrasporange. The four spores
are sometimes arranged in a row, when they are called zonate ; more
often as quadrants of a sphere, when they are cruciate : rarely there are
only one or two, or occasionally eight. In the Ulvaceae, Lemaneaceae,

FIG. T.-j2.—Crouania attemtata Ag. «, branch (x 40) ; B, apex of branch (x 100) ; c, lower ;
portion of branch with tetrasporanges ( x 100). (After Kiitzing.)

and in some Nemalieae they are altogether wanting. The tetraspores
(see fig. 231) may be formed in the six following ways : — (i) The
whole contents of the sporange become a single spore ; (2) the contents
divide into two equal parts by a transverse wall ; (3) they divide into
four quadrants by two successive bipartitions ; (4) they divide into four
tetrahedra by simultaneous quadripartition ; (5) they divide into four
by three parallel transverse walls ; (6) the contents divide into more
than four spores. On germination the tetraspores may give birth either
to sexual or to non-sexual individuals. In the monosiphonous Florideae
the tetrasporanges are usually formed at the expense of the ultimate
branchlets. In other forms they are most commonly found scattered

o 2

196

ALG^E

near the margin of the ' frond,' sometimes (Rhodymenia bifida, Ktz.) im»
bedded in the thallus, and then often grouped into sori (Nitophyllum,,
Grev.) ; or, in the Corallinaceae, enclosed in special conceptades. In
other genera (Phyllophora, Grev., &c.) they are developed in nematheces^
wart-like elevations of the surface, where they are accompanied by barren
hyphae or paraphyses. In others again they are borne on metamorphosed
pod-like branches known as stichids, as in Dasya (Ag.), Plocamium (Lmx.),
&c. Only in the Porphyraceae are the tetraspores endowed with a slow

FIG. 173. — Xitophyllum punctatuin Harv. «, piece of frond with tetrasporanges (natural size) ; b, piece
of the thallus with tetrasporanges (x 100) ; c, section through frond showing cystocarp(x 100 .
(After Kiitzing.)

amoeboid motion. Zoospores are altogether unknown in the class, except
in the Ulvaceae ; but other modes of non-sexual propagation occur in a
few cases. In some genera of Ceramiaceae special organs occur, known
as seirospores. Melobesia is characterised by the production of genuine.
In Monospora (Sol.) stalked gemmae or propagules are produced at the
forks of the branchlets, and readily become detached, apparently repla-
cing the sexual organs, which are unknown in the genus. Lemanea
(Bory) increases by budding. In Hydrolapathum peculiar bud-like
prolifications are produced on the stem (see fig. 171).

FIG. 174. — Dasya elegans Ag. a, piece of frond with tetrasporanges ; b, piece with cystocarp
(natural size) ; c, branch with stichids ( x 100) ; d, cystocarp (x 25). (After Kiitzing.)

i98

A true understanding of the sometimes complicated process of sexual
reproduction in the Florideae has been much obscured by the numerous
terms employed by the older writers for identical organs, and by incor-
rect notions as to their functions. The true sexual organs, antherids
and procarps, are nearly always formed on individuals which do not
produce tetraspores ; and the sexual individuals may be monoecious or
dioecious ; the latter is the most common condition. If the Ulvaceae
are rightly included under Florideae, we have here a wide departure from

FIG. 175. — Stages in the development of the reproductive organs of Neinalion ntultifidum Ag.
(magnified). (Spennat. = pollinoids.)

the normal type, sexual reproduction taking place by the conjugation of
motile swarm-cells.

The antherid consists, in its simplest form (Porphyraceae), of a soli-
tary cell at the end of a long segmented branch ; and in this case it
gives birth to a single pollinoid ; in other forms the antheridial cells
occupy a similar position to the tetraspores, being formed in groups at
the expense of the ultimate branchlets. They are also sometimes pro-

FLORIDE^E

199

duced, like the tetraspores, in wart-like protuberances or nematheces on the
surface of the thallus, and interspersed with paraphyses, sometimes
(Gracilaria, Grev.) in depressions which are overarched by the surround-
ing tissue ; or, in the Corallinaceae, in special conceptades. When the
thallus is otherwise unilamellar, as in Porphyra (Ag.), the spots where the
antherids are formed divide by walls parallel to the surface. The fer-
tilising bodies or pollinoids are naked masses of protoplasm, of a spheri-
cal or elongated form, sometimes with a beak-like appendage, and are
discharged in succession one after another. They are carried along
passively by the water, and are distinguished from the antherozoids of
other Cryptogams by the absence of cilia, and, in most cases, of any
spontaneous power of motion. Wright (Trans. Irish Acad., 1879, P- 27)

FIG. 176. — SperiHothamnion Jiennaphrodititni (magnified). A , branch with procarp
(tfg z) and antherid (an) before fertilisation ; J5, after fertilisation, the cystocarp
developing ; t, trichogyne ; c, trichophore ; g, carpogenous cells. (After Nageli.)

states that in Griffithsia (Ag.) the pollinoids have an obscure amoeboid
motion, as they have also in the Porphyraceae ; according to Dodel-Port
their access to the trichogyne is greatly facilitated by the currents made
in the water by Vorticelke and other Infusoria ; and there can be little
doubt that fishes which feed on seaweeds are an important agent in pro-
moting their fertilisation. The pollinoids and the tetraspores appear to
be homologous in their origin.

The female organ before fertilisation — corresponding functionally
to the pistil of Flowering Plants — is termed the procarp. In its simplest
form (Porphyraceae and Nemalieae) it consists of a single cell with a
lateral hair-like prolongation, the trichogyne. But in all the higher
forms the procarp is composed of one or more fertile cells constituting
the carpogone^ and one or more infertile cells which make up the tricho-

200

ALG.-E

phore, the function of which is to convey the fertilising substance from
the trichogyne to the carpogone. The procarp is usually formed on the
youngest parts of the plant, and .often originates from the terminal cell
of a lateral branch. Occasionally each carpogone has two trichogynes
and two trichophores ; or, again, each trichophore may be connected
with two carpogones. The trichogyne often becomes eventually coiled

FIG. 177. — Lejolisia itiediterranea Born, a, filament with tetrasporange ; I', plant
with cystocarps and antherids ; c, empty cystocarp (x 150). (After Bornet.)

spirally at its base. It does not open to admit the entrance of the
pollinoids ; in the act of impregnation these bodies attach themselves
to a spot near the apex of the trichogyne, and at the same time clothe
themselves with a cell-wall. At the point of contact the cell-wall of both
trichogyne and pollinoid is absorbed ; the contents of the latter pass
through the trichogyne and the trichophore to the carpogone, impregnat-

201

ing its contents, and the trichogyne then disappears. The carpogone
now divides by a horizontal wall into two cells ; the upper one of these
is functionless, and ultimately disappears ; the lower one contains the
impregnated oosphere or carposperm. The carposperm does not, how-
ever, in any case possess the power of germinating directly. In the
Porphyraceae it breaks up into
eight portions, the carpospores,
which germinate after moving
about with a slow amoeboid mo-
tion. In all the other orders
the contents of the carpogone
undergo, after impregnation,
more complicated divisions, and
become differentiated into a
sterile and a fertile portion, the
placenta and the nucleus. The
placenta may consist of one or
more cells, and frequently occu-
pies the larger portion of the
carpogone ; or it may be re-
duced to very small dimensions.
The nucleus is the mass of carpo-
spores, and may be made up
of a number of secondary nuclei.
The mass of carpospores is
sometimes, as in Callithamnion,
completely exposed except for a
gelatinous membrane by which
it is surrounded • but much
more often there is gradually
formed round the nucleus after
impregnation, not only a layer
of mucilage, but also a more or
less hard solid layer, the peri-
carp; and the whole structure
thus constituted is then known
as the sporocarp or cystocarp. From this cystocarp the carpospores
escape, when ripe, either by the decay of the pericarp ('coccidium' of
the older systematists), or through an opening at its apex, the carpostome
(' ceramidium ' of older writers). In some genera (Polysiphonia, Lejolisia,
Born., Bonnemaisonia, Ag.) the cystocarp is completely exposed, con-
spicuous, and sometimes stalked ; but it is usually, as in Gracilaria,

FIG. 178. — Gracilaria. compressa Ag. Branch with
cystocarps (natural size). (After Hauck.)

202

ALG^E

more or less imbedded in the thallus, often in special fertile branches ;
and its situation is then usually indicated by an external wart-like
swelling. In Polyides (Ag.)j the Squamariaceae, and other forms with
a perfectly flat frond, the cystocarps are enclosed in nematheces.

In a considerable number of Florideae the formation of the cystocarp
is a more complicated process than that already described, the process
of impregnation consisting of two distinct stages — (i) the fertilisation
of the trichogyne by the pollinoids ; and (2) the fertilisation by the
impregnated trichophore-cells of the carpospores, which may be at some
considerable distance from the trichophore and trichogyne, even on a

FIG. 179. — Dudresnaya cocclnea Crouan. /, young trichophore. //, young trichogyne ;
f, young fertilising tubes. ///, impregnated trichophore with pollinoids on the coiled tncho-

fyne,^; the fertilising tube,./', impregnating successively the carpogones, VII, VI, and V,
V, carpogone before fertilisation ; c, carpogenous cell. VIII, masses of carpospores.

different branch. This is effected by means of long simple or branched
tubes, the fertilising-tubes, or ' ooblastema-filaments ' of Schmitz. The
following is the process as it takes place in Dudresnaya (Born.). The
trichophore consists of a row of cells which, before fertilisation, put out
short branches, which subsequently develop into long tubes. No carpo-
gone is found in the immediate neighbourhood of the trichophore ; but
at some distance are a number of short segmented filaments, the termi-
nal cells of which are considerably larger than all the rest. These cells
are carpogones. The fertilising-tubes make their way between the fila-
ments or hyphae of which the thallus is composed, come into contact

FLOR1DE& 203

with the carpogones, and convey to them the fertilising principle from
the trichophore. The result is that each carpogone develops into a
cystocarp containing carpospores. A single fertilising-tube may in this
way impregnate a number of carpogones.

Schmitz describes the process of secondary impregnation in the more
highly developed Florideae as consisting in the fertile cells (carpogones)
entering into communication, through orifices in their cell-walls, with
certain special sterile cells rich in protoplasm, the auxiliary cells, to
which the fertilising material is brought from the trichophore by the
ooblastema-filaments. The details of this conjugation between the
auxiliary cells and the carpogones are subject to great variation in
different genera. In some cases the protoplasmic contents of the two
cells coalesce completely, while in others their nuclei still remain distinct
after conjugation. The carposperm, or cell resulting from this conjuga-
tion, then grows rapidly, and peripheral cells divide off from it, leaving
a large central cell which alone remains sterile, all the peripheral cells
developing into carpospores. In the Corallinaceae the ooblastema-fila-
ment enters into conjugation successively with several neighbouring
auxiliary cells. In a larger number of genera the process is as follows : —
A short branch of the carpogone, usually consisting of three or four cells,
becomes attached laterally to a branch of the thallus, and curves in such
a way that the carpogone-cell is closely applied to the nearest auxiliary
cell, or reaches it by means of a short protuberance from one or both
of the conjugating cells. The entire oosphere, or at all events its nucleus,
then passes over into the auxiliary cell. In the Gigartinacese the auxiliary
cell itself becomes the central cell of the cystocarp.

LITERATURE.

Nageli u. Cramer— Pflanzenphysiol. Untersuch., 1855, 1857.

Pringsheim — Monber. Bed. Akad. Wiss., 1855, p. 133 (Quart. Journ. Microsc. Sc. ,

1856, p. 124).
Rosanoff — (Rhodospermin) Mem. Soc. Sc. Nat. Cherbourg, 1856; Ann. Sc. Nat.,

iv., 1865, p. 320 ; and Compt. Rend., Ixii., 1866, p. 831.
Van Tieghem— Compt. Rend., Ixi., 1865, p. 804.
Solms-Laubach— Bot. Zeit., 1867, p. 161.
Askenasy — (Rhodospermin) Ibid. , p. 233.
Sorby — (Rhodospermin) Journ. Microsc. Soc., 1871, p. 124.
Klein — Flora, 1871, p. 161 ; and 1880, p. 65.

Agardh— Epicrisis Syst. Florid., 1876; and Florid. Morpho]. (with atlas), 1879.
Bornet and Thuret— Notes Algologiques, fasc. i. and ii., 1876, 1880; and Etudes

Phycol., 1878.

Falkenberg— Nachricht. Gesell. Wiss. Gottingen, 1879 and 1880.
Ambronn— Bot. Zeit., 1880, p. 61 ; and Sitzber. Bot. Verein Brandenburg, 1880,

p. 74.

204 ALG&

Schwendener — Monber. Preuss. Akad. Wiss., 1880, p. 327.

Berthold— Pringsheim's J ahrb. wiss. Bot., 1882, p. 569.

Schmitz— Sitzber. Akad. Wiss. Berlin, 1883, p. 215.

Ardissone— Phycol. mediterranea, Part i., Florideae, 1883.

Buff ham— Journ. Quek. Micr. Club, 1884, p. 337.

Massee — Journ. Microsc. Soc. , 1884, pp. 198 et seq. ; and 1886, p. 561.

Wille— (Tissue-systems) Bot. Salsk. Stockholm (see Bot. Centralblatt, xxi., 1885,

pp. 282, 315; xxiii., 1885, p. 330; andxxvi., 1886, p. 86) ; and Nov. Act.

Leopold-Carol. Akad., Hi., 1888, p. 51.
Schiitt— (Phyco-erythrin) Ber. Deutsch. Bot. Gesell., 1888, p. 36.

A complete classification of the very numerous types of structure
belonging to the Florideae would carry us beyond our present limits ;
and the principles of such a classification are by no means agreed on
by the best authorities, many details connected with the process of
fertilisation being still obscure. Agardh, in his 'Epicrisis,' divides the
family into six groups, dependent on the structure and mode of develop-
ment of the cystocarp, and into twenty-two orders. We shall therefore
confine ourselves to an account of some groups or special forms, the
structure of which has been specially studied, commencing with the most
highly differentiated orders.

In the CERAMIACE^:, which are exclusively marine, are included a
considerable number of the more delicate red seaweeds of our own and
other coasts, included in the genera Callithamnion (Lyng.), Grifnthsia
(Ag.), Ptilota (Ag.), Crouania (Ag.), Ceramium (Lyng.), and others. The
thallus is either monosiphonous and uncorticated, or more or less corti-
cated. In Crouania (fig. 172) the branches are beautifully whorled. The
procarp frequently consists of a carpogone and two trichogynes. The
cystocarps are formed externally on the branches or at their base, and are
frequently closely surrounded by them as by an envelope. With rare ex-
ceptions the cystocarp consists of a roundish or lobed nucleus, enclosed
in a colourless gelatinous membrane, without any pericarp, and composed
of a larger or smaller number of closely packed carpospores. The tetra-
sporanges are usually external, and the mode of division of their contents
varies greatly. The complicated process of fertilisation in Dudresnaya
has already been described. In addition to the tetraspores, two other
special kinds of non-sexual organs of propagation occur in the order.
Some species of Ceramium are characterised by the presence offavella,
dense agglomerations of spores, resembling the cystocarps, but pro-
duced at the ends of branches, quite exposed except for a thin colourless
membrane. They appear to be homologous to the multipartite tetra-
sporanges. Callithamnion seirospermum (Griff.) (Seirospora Griffithsiana,
Harv.), C. versicolor (Drap.), and some other species, produce seirospores,

FIG. 181. — Branch of Ceramium strict urn Grev.
with favellae ( x 40). (After Kutzing.)

FIG. 1 80.— Branch of Cattithamnio-i
seirosperinum Griff., with se:rospores
( x :oo). (After Kutzing.)

FIG. \%z,—Melobesia. membranacea, Lmx. a, vertical
section through female conceptacle ; l>, vertical section
through conceptac'.e with tetraspcranges ; c, vertical
section through male conceptacle (x 350); d, pol-
linoids ( X 1300). (A' .cr Rosanoff.)

206

ALG^E

branched rows of roundish or oval spores resulting from the division
of terminal cells of particular branches, or produced on the main

branches.

LITERATURE.

Cramer— Pflanzenphysiol. Untersuch., 1857 and 1863.
Nageli— Sitzber. Munch. Akad. Wiss., 1861, p. 297.
Pringsheim — Abhandl. Berlin. Akad. Wiss., 1862, p. I.

The CORALLINACE^E (Corallina, L., Melobesia, Lmx., Litholhamnion,
Phil., Amphiroa, Lmx., &c.) are distinguished from other marine

^ul,!^-- ' : •' •'" ^iiiaiiSbua»

FIG. 183. — Corallina officinalis L. a, longitudinal section through conceptacle with tetrasporanges ;
b, longitudinal section through cystocarp (x 100). (After Bornet.)

algae by their calcareous habit. Most of the species are natives of
warmer seas. In Corallina the thallus is at first soft and flexible,
but it soon becomes very hard and brittle from the deposition of
calcium carbonate. The red colour and branching habit give this
genus a remarkable resemblance to small corals, as in C. officinalis (L.),
the common ' coralline ' or ' nullipore ' of our southern coasts. Many
species of Melobesia (fig. 182), Lithothamnion, Lithophyllum (Phil.), and
other genera, grow as lichen-like incrustations or in the form of small flat

FLORWEJE

207

discs attached to rocks, or on the leaves of Zostera, or on other seaweeds.
The sexual reproductive organs and the lion-sexual organs of propaga-
tion are alike formed in small cavities or conceptacles, which are either
entirely imbedded in the thallus, or more often form external wart-like or
ovoid swellings. The female conceptacle opens at the apex by an ostiole
(fig. 182, a); the very short sporiferous filaments, the terminal cells of which

V

ft \

FIG. 184. — Coraliina rubens L. a, branch with three cystocarps and a male conceptacle ; con-
ceptacles of Melobesia, Thureti Born, are attached to the upper part of the branch ( x 20) ; £, longi-
tudinal section through a male conceptacle deprived of its calcareous incrustation ( X 160) ; c, pol-
linoids(x 400). (After Bornet.)

become the carpospores, spring from the base of the cavity, and are
accompanied by paraphyses. The male conceptacles are of similar
structure ; the pollinoids (fig. 182, d) possess one or two short appen-
dages. The non-sexual present a general resemblance to the sexual
conceptacles ; the tetrasporanges spring from their base and sides, and
are accompanied by paraphyses ; the contents of the sporange not un-

208

ALG^E

frequently divide into only two tetraspores. The conceptacles are not
unfrequently surmounted by singular horn-like processes. Melobesia
produces peculiar branching septated gemma:.

LITERATURE.

Rosanoff— Mem. Soc. Sc. Nat. Cherbourg, 1866.

Areschoug— Observ. Phycol,, iv., 1875.

Solms-Laubach — Die Corallinenalgen d. Golfes Neapel, 1881.

The greater number of our red seaweeds belong to the following
orders, established by Agardh, the boundaries of which are not in all

FIG. T&s. — Chondrns crispus Stackh. a, with cystocarps (natural size) ; b, uppermost portion of
frond with tetrasporanges (natural size) ; c, section through the frond and a portion of the cystocarp
(x 100). (After Kiitzing.)

cases well defined, and in regard to many of which much yet remains
to be discovered as to their mode of reproduction, viz.: — CRYPTONEMIA-
CE^E (Nemastoma, Ag., Grateloupia, Ag., Halymenia, Ag., Dumontia,
Lmx., Cryptonemia, Ag., &c.), GIGARTINACE^: (Chondrus, Grev., Gigar-
tina, Lmx., Kallymenia, Ag., &c.), RHODYMENIACE^E (Rhodymenia,
Grev., Chylocladia, Grev., Plocamium, Lmx., Hydrolapathum, Rupr.,
&c.), DELESSERIACE^E (Nitophyllum, Grev., Delesseria, Lmx.), SPH^ERO-
COCCACE^E (Sphserococcus, Stackh., Gracilaria, Grev., &c.), HYPN^EACE/E

FLORIDE.&

209

(Hypngea, Lmx.), GELIDIACE^E (Gelidium, Lmx., &c.), SPONGIOCARPE^E
(Polyides, Ag.), LOMENTARIACE^: (Lomentaria, Gaill.), RHODOMELACE^E
(Laurencia, Lmx., Chondria, Ag., Rhodomela, Ag., Polysiphonia, Ag.,
Rytiphlaea, Ag., Amansia, Lmx., Vidalia, Ag., Dasya, Ag., Pollexfenia,
Harv., &c.), SPYRIDIACE^: (Spyridia, Harv.), and WRANGELIACE^E (Sper-
mothamnion, Aresch., Bornetia, Thur., Lejolisia, Born., Wrangelia, Ag.,
&c.). A peculiar mode of fertilisation is described in the case of
Gracilaria confervoides (Grev.). The procarp is composed of six or seven
cells, and its position is indicated by an external swelling on the
* frond ; ' the pericarp is
formed before fertilisation.
The cells both of the pro-
earn and of the placenta
fuse together by the dis-
appearance of their cell-
walls ; and the fused cells
of the procarp and of the
placenta are placed in
communication with one
another by protoplasmic
protrusions or diverticula,
proceeding from the fused
cells of the procarp and
passing through their
swollen walls. The cells
which form the free sur-
face of the placenta now
produce radiating rows of
spores formed basipetally,
while from the fused pro-
carpial cells other diverti- FIG
cula arise which also form
spores at their free ends

independently of the placental cells. It would appear as if by this
means a portion of the protoplasm of the pollinoid were conveyed
through the trichogyne and the procarpial cells, which play the part of
the auxiliary cells of Dudresnaya, to the placental cells. In Polyides
the cystocarps are congregated in external amorphous wart-like ex-
crescences formed of vertical confervoid filaments, of which the carti-
laginous ' frond ' is almost entirely composed, set in firm jelly.

Plocamium coccineum (Huds.) is one of the most abundant of our
red seaweeds. Rhodymenia palmata (Grev.), a very common red seaweed,

86. — Rhodymenia Palmetto. Grev. a, with tetraspo-
ranges (natural size) ; ft, section through apex of frond with
tetrasporanges ( x 100). (After Ktitzing.)

210

ALG^E

is eaten in Scotland under the name of ' dulse.' Chondrus crispus (L.)
is known, when dried, as ' carrageen ' or ' Irish moss.' Gracilaria lichen-
oides (L.), which yields copious gelatine, known as ' Fucus amylaceus,'
is largely used as an article of food in Ceylon and on other tropical
coasts. Japanese isinglass is a product of species of Gelidium. The

FIG. 187. — Vertical median section of swelling on frond of Gracilaria confervoides Grev.
/, /, cells of procarp ; pc, placental cells ; s, s, s, spores (x 400). (After Johnson.)

substance known to microscopists as 'agar-agar' is yielded also by
Gracilaria lichenoides, Eucheuma spinosa (Ag.), and other seaweeds.
Several other species are employed in different parts of the world as glues
and varnishes. Marchesettia spongioides (Hauck) (Areschougiaceae),
from Singapore, has a remarkable resemblance to a sponge.

LITERATURE.

Berthold— (Cryptonemiacese) Fauna u. Flora Golfes Neapel, 1884.
Johnson — (Gracilaria) Annals of Botany, i. 1888, p. 213.

The SQUAMARIACE^E (Hildenbrandtia, Nard., Cruoria, Fries, Peysson-
nelia, Dene., &c.) are a small group of small marine, or rarely fresh-water
Algae, growing on stones or on the shells of molluscs or Crustacea, or
attached to larger algae. The ' frond ' is expanded flat or hemispheri-
cal, gelatinous, membranaceous, or crustaceous, with lichen-like habit,
composed of a single layer of cells, or more often of short densely

FLO RIDE A: 211

packed vertical filaments. The species of Hildenbrandtia form rose-
coloured incrustations on rocks, stones, and shells in salt or (H. rivularis,
Ag.) running fresh water. The tetrasporanges are either terminal cells
of special filaments, enclosed in a gelatinous coating and rising verti-
cally from the flat thallus ; or they are formed in nematheces, in external
wart-like protuberances, or in depressions in the surface of the thallus.
The cystocarps are also either formed in nematheces, or are external,

FIG. 188. — Hildenbrandtia prototypus NarHo. Vertical section through thallus, showing
three conceptacles with cystocarps ( x 300). (After Kiitzing.)

springing from moniliform fertile filaments. It is stated that there are
sometimes two kinds of carpogone, one provided with a trichogyne, the
other not. After a carpogone of the first kind has been fertilised
through its trichogyne, it puts out a fertilising-tube or 'ooblastema-
filament,' which impregnates a carpogone of the second kind. In
Hildenbrandtia a large number of antherids are developed from a single
cell of the thallus.'

LITERATURE.

Schmitz — Sitzber. Niederrhein. Gesell., 1879.
Borzl— Rivista Scientifica, 1880.
Petit— Bull. Soc. Bot. France, 1880, p. 194.
Wollny — Hedwigia, 1886, pp. I and 125.

The HELMINTHOCLADIACE^E (including Nemalieae, Batrachospermeae,
and Chaetangiaceae) comprise a number of marine (Helminthocladia, Ag.,
Nemalion, Ag., Liagora, Lmx., Galaxaura, Lmx., &c.) and fresh- water
(Chantransia, Fries, Batrachospermum, Roth, Thorea, Bory) forms, the
relationship of which to one another is uncertain, and the family is not
likely to be one that will be ultimately retained. The fresh-water
species are mostly of small size, but of great beauty from the elegant
symmetry and arrangement of the branches. The ' frond ' of Liagora
and Galaxaura is calcareously incrusted, like that of a coralline ; that of

P 2

212

ALG&

some other genera is very soft and gelatinous : the whole is usually
enclosed in a gelatinous envelope. The thallus is of filamentous struc-
ture, and either simple or branched, the
secondary axes often arranged in whorls.
The main axis usually consists of a central
row of cylindrical cells surrounded by a
pseudo-cortex composed of smaller cells,
either placed in rows at right angles to
the axis, or parallel to it. It may, how-
ever, consist of a single uncorticated row
of cells. Batrachospermum is a genus of
small green fresh-water Algae of great beauty
from the symmetry of their branching. The
stem grows by means of a cup-shaped

FIG. T%g.—Batrachosp'rjmim monilifonne Roth, a, portion of plant ( x 30) ; />, portion with
cystocarps, c cc c ( x 150). (From nature and after Cooke.)

FLORIDE&

213

apical cell, which divides by septa ; the
resulting cells do not divide further, but
elongate and swell somewhat at each end
into a bone-shaped form, producing the
whorled branches. From the basal cells of
these branches secondary branches grow
vertically downwards over the main axis, pro-
ducing the pseudo-cortex. According to
Sirodot, absorption takes place only in special
thin - walled cells ; the resting-cdls, with
thicker walls, often display continuity of pro-
toplasm. In Nemalion and Batrachospermum
the procarp is unicellular, and bears at its
apex the long thin-walled trichogyne. The
antherids are scattered in groups at the end
of peculiar ovoid cells. After fertilisation
the carpogone divides by longitudinal walls
into a multicellular glomerule enclosed in a
gelatinous envelope ; the terminal cells of
the branches of the glomerule produce the
spores. The cystocarps are external in the
axils • of the branches in Chantransia and

FIG. 190. — Chantransia -virga-
tuln Thur. with tetrasporanges
( x 100). (After Kiitzing.)

FIG. 191. — C. corymbosa Thur. 7, unicellular procarp, b,
with pollinoid attached. 1 1-V> stages in the branching of
the procarp after impregnation (x 400). VI, cystocarp
( x 250). (After Thuret.)

214 ALG^E

Batrachospermum, more or less imbedded in the thallus in the other
genera of the order. In several of the genera tetraspores are unknown.

A very singular genetic connection exists between the genera Chan-
transia and Batrachospermum, it being possible to transform the former
into the latter by changing its conditions of life. The germinating
carpospores of Batrachospermum put out a kind of protoneme, which is
the Chantransia of Fries, the non-sexual generation of Batrachospermum ;
this can propagate itself by simple budding from generation to genera-
tion, producing, as a rule, as its organs of propagation, only non-sexual
tetraspores. Chantransia grows especially in dark situations under water,
and, when transferred to the light, undergoes a metamorphosis. There
springs up from the Chantransia protoneme a branch which is in every
respect a Batrachospermum, and which bears sexual organs only, and
no tetraspores. On one species only of Chantransia, C. corymbifera
(Thur.), are sexual organs known. Although this phenomenon is some-
times spoken of as an example of ' alternation of generations,' it is not
identical with the process known under that name in the higher Crypto-
gams, being rather a difference in the mode of development dependent
on a change in the vital conditions.

LITERATURE.

Solms-Laubach— Bot. Zeit. , 1867, p. 161.

Sirodot— Compt. Rend., Ixxvi., 1873, pp. 1216, 1335 ; Ixxix., 1874, p. 1366; xci.,

1880, p. 862 ; xcii., 1881, p. 993 ; Bull. Soc. Bot. France, 1875, P- 128; and

Les Batrachospermees, 1884.

Arcangeli— Nuov. Giorn. Bot. Ital., 1882, p. 155.
Massee — Journ. R. Microsc. Soc., 1886, p. 561.

The LEMANEACE.E are a small group of fresh-water Algae, comprising
the genera Lemanea (Bory) and Sacheria (Sir.), growing in rapidly running
water, as beneath mill-wheels. The thallus is filiform and cartilaginous,
of a dull grey or greenish colour, and consists of a single row of tubular
cells, or of an axial row surrounded by rows of smaller cortical cells ; it
displays swellings or projections at regular intervals. It grows by means
of an apical cell, from which segments are cut off at right angles to the
direction of growth. By transverse septation each segment divides into
a central cell surrounded by peripheral cells ; the central cell becomes
a member of the central axis, the peripheral cells members of the cortical
tubes. The ' frond ' increases by budding at the free surface of the
rooting system, finally producing csespitose tufts. No non-sexual spores
are known. The only other mode of reproduction is sexual. The
antherids are short cylindrical cells produced externally in the neigh-

FLORIDE& 215

bourhood of the swellings, with a more or less regular annular arrange-
ment. The trichogyne is a long transparent cylindrical tube, simple or
branched, produced within the tubular thallus. The procarp is unicel-
lular, and of a very simple structure. The carpogone puts out before
impregnation a number of segmented filaments resembling paraphyses,
and enclosed in a transparent jelly. After the oosphere has been im-

FIG. 192.— A , Lemanea nodosa Ktz. (natural size). B, section of tube with female organs ; t,
trichogyne, at the base of which sporiferous filaments (.$•) are beginning to be formed ( x 200).
C, transverse section of male organs ; a, antherids ( x 400). (After Sirodot.)

pregnated, it puts out an ' ooblastema-filament,' and the trichogyne
disappears ; at the extremity of this filament are produced the carpo-
spores. 'On germinating the carpospore puts out a protonemal
filament somewhat resembling that of mosses, on which the fertile axes
are produced as lateral branches. This is regarded by some as a rudi-

216

ALG^E

mentary alternation of generations ; and Peter asserts (Bot. Verein
Miinchen, Feb. 28, 1887) that the sexual form of Lemanea fluviatilis (Ag.)
may develop out of heteromorphic branches of a Chantransia.

LITERATURE.

Wartmann— Beitr. zur Anat. und Entwick. der Lemanea, 1854.

Sirodot— Ann. Sc. Nat., xvi., 1872, p. 5; 1873, p. 241 ; and Compt. Rend., Ixxix.,

1874, p. 1366.
Ketel— Anat. Untersuch. iiber Lemanea, 1887.

The PORPHYRACE^E or Bangiaceaa are marine or fresh-water Algae
belonging to the two genera Porphyra (Ag.) and Bangia (Lyngb.). They
are regarded by some authors as much lower in structure than the red

FIG. 194. — B.fnsco-purpurea Lyngb. Filament
in different stages of development (-X 200).
(After Kiitzing.)
FIG. 193. -a, b, Bangia ceramicola
Chauv. Portions of barren and fertile
filaments (x 330). (After Thuret.)

seaweeds, but are best placed at present, from their mode of sexual
reproduction, as one of the lowest families of Florideae. The thallus is
either filiform (Bangia), or is a thin transparent plate (Porphyra) com-

FLORIDE^E

217

posed, in its vegetative portion, of a single layer of cells ; in both cases
coloured by phycoerythrin. The tetrasporanges and the male and
female organs appear to be homologous to one another, and not to be
sharply differentiated. The tetraspores are motile for about forty-eight
hours after their escape from the tetrasporange ; by some writers they are
described as being endowed with an amoeboid change of form. The
trichogyne is quite rudimentary ;
the pollinoids attach themselves
singly or- in numbers to the fertile
portion of the thallus' where the
oogones or rudimentary carpogones
occur. While in this position they
are invested by a thin cell-wall of
cellulose, and then put out a slender
thread of protoplasm which pierces
the cell-wall of the oogone, nearly
the whole of the protoplasm of the
pollinoid passing into this organ.
According to Berthold, the contents
of the oogone break up, after impregnation, into eight carpospores,
the ' octospores ' of Janczewski, which move about, on escaping, in an
amoeboid manner, putting out and withdrawing protoplasmic protru-
sions, then come to rest and germinate. Porphyra vulgaris (L.), not
uncommon on the coasts of Western Europe, is eaten under the name
' purple laver.'

LITERATURE.

Janczewski — Ann. Sc. Nat., 1873, p. 241.

Reinke — Pringsheim's Jahrb. wiss. Bot., 1878, p. 274.

Goebel— Bot. Zeit., 1878, p. 199.

Berthold — Mittheil. Zool. Stat. Neapel, 1880 and 1882.

FIG. 195. — Tetraspores of Bangiafiisco-purpu-
rea Lyng., showing amoeboid changes of form
(magnified). (After Reinke.)

The position of the ULVACE^E is still uncertain. The group includes
a small number of genera— Ulva (L.), Enteromorpha (Lk.), Phycoseris
(Ktz.), Prasiola (Ag.), and Monostroma (Thur.) — of fresh-water or more
often of marine or brackish Algae, of a bright green colour, consisting of
a flat usually ribbon-shaped plate, composed of either one (Monostroma)
or two (Ulva) layers of cells ; less often (Enteromorpha) having the
form of a tube. The cells are sometimes arranged symmetrically in
groups of four (Prasiola). The male and female reproductive organs,
which are rudimentary in the Porphyraceae, are entirely suppressed in
the Ulvaceae, and we find a reversion to a much simpler mode of repro-

218

duction in the conjugation of equivalent swarm-cells. Ulva produces
two kinds of swarm-spore — megazoospores with four cilia, and micro-

.^ob- *
jy^x

'cgp^o^aoOQ'

PQ^P^RQR
wSJ^y

v^^^O^/r^0/

FIG. 196. — Ulva.

a, portion of frond showing cells which produce the swarm-spores ; b, portion of
frond with empty cells ; c, megazoospores (magnified).

zoospures or zoogametes with two cilia ; and
these two kinds are produced either on the same
or on different individuals. The megazoo-
spores germinate directly. Conjugation of the
smaller swarm-cells has been observed in Ulva,
Enteromorpha, and Monostroma, but the
coalescence takes place only gradually ; some
time after conjugation four cilia and two
pigment-spots are still to be detected. In
Ulva the zygosperm thus formed divides re-
peatedly after becoming attached to some solid
substance ; the cells thus formed separate, and
a small colony of multicellular individuals is
produced, each of which develops into a new
' frond,' dividing first into a filament and then
into a plate. In Monostroma a non-sexual
mode of propagation has been observed. At

FIG. 197.— Enteromorpha intestinalis
Lk. (natural size). (After Hauck.)

FIG. 198. — Stages in the conjugation of the zoogametes
of Monostroma bullosiim Thur. (magnified).

FLOR1DE& 2i9

certain spots the cells divide in a direction parallel to the plane of the
thallus, and a small projection is thus formed which becomes detached
and develops into a new ' frond.' Geddes (Trans. R. Soc. Edinburgh,
1 88 1, p. 555) describes also a process of gemmation in Enteromorpha.
The ordinary mode of reproduction in the Ulvaceae so closely resembles
that in the Confervaceoe that the two families are generally considered
as nearly allied ; but the difference in the structure of the thallus is so
great that it is difficult to believe in any near affinity between them.
On the other hand, the structure of the thallus in Ulva and Porphyra is
almost identical ; and it is at least as probable that the Ulvaceae are
derived from the Porpt^yraceae by further retrogressive metamorphosis
displayed in the comirfete suppression of the antherids and carpogones,
and the reversion of me tetraspores into motile swarm-spores of two kinds,
the smaller of which are zoogametes. On the other hand, Monostroma
may be allied to Tetraspora among the Protococcaceae. Several species
of Enteromorpha form a large portion of the green vegetation in salt
ditches or on muddy sea-shores, or on rocks between high and low water
mark ; Prasiola grows on bare rocks or stones, or on salt soil ; the
substance known as ' green laver ' consists of several species of Ulva.

LITERATURE.

Jessen — Prasiolae Monographia, 1848.
Thuret— Mem. Acad. Sc. Nat. Cherbourg, 1854, p. 9.
Wittrock — Monogr. Monostroma, 1866.

Janczewski et Rostafinski — Mem. Acad. Sc. Nat. Cherbourg, 1874, p. 369.
Areschoug — Bot. Notiser, 1876.
Thuret et Bornet— Etud. Phycol., 1878.
Reinke— Pringsheim's Jahrb. wiss. Bot., 1878, p. 531.
•Borzl— Studi Algologici, 1883.

Class XL— Confervoidese Heterogamae.

The small group of green fresh- water Algae comprised in this class
form a connecting link between the lower Florideae and the Isogamous
Confervoideae, from which latter they are distinguished by the sharp
differentiation of their male and female organs of reproduction. In the
highest order, the COLEOCH^TACE^E, the mode of reproduction bears a
striking analogy to that in the Nemalieae, being effected through the
agency of a tubular trichogyne ; but the male elements are no longer
immotile pollinoids, but motile swarming antherozoids, naked biciliated
or multiciliated protoplasmic bodies, but much more closely resembling
the corresponding structures in the lower Algae than the coiled anthero-

220 ALG^E

zoids of the Muscineae and Vascular Cryptogams. The vegetative
thallus is here either composed of branching filaments, or is reduced to
a flat plate of cells. In the two lower orders, the CEDOGONIACE^E and
the SPH^ROPLEACE^E, it consists of an unbranched filament of uni-
nucleated or multinucleated cells ; and in them the impregnation of the
oosphere by the motile antherozoids is brought about directly, without
the intervention of a trichogyne. Non-sexual propagation by means of
swarming biciliated zoospores, formed within zoosporanges, and bearing a
close resemblance to the antherozoids, occurs in the Coleochaetaceae and
Sphaeropleacae ; in the QEdogoniaceae the zoospores are much larger
bodies, bearing a tuft of cilia. The class displays a rudimentary alter-
nation of generations.

ORDER i. — COLEOCH^TACE^:.

The typical genus of this small order, Coleochczte (Breb.), comprises
several species of small fresh- water Algae forming minute discs or cushions
attached to submerged plants, from -^ to £ inch in diameter, consisting,
in the simpler forms, of a single layer of cells, often arranged in rays
proceeding from a common centre. Some of these cells are furnished
with colourless bristle-like protuberances fixed into narrow sheaths. All
the cells of which the thallus is composed usually lie in one plane, but
their degree of union with one another varies. In C. scutata (Breb.)
they are closely united into a compact disc, which continues to grow by
peripheral increase, the marginal cells dividing by radiating and tangential
walls. In C. soluta (Pringsh.) the thallus consists of a number of branches,
which ramify dichotomously, and lie side by side, more or less closely
crowded, in one plane. In other species, as C. pulvinata (A. Br.) and
divergens (Pringsh.), the branches do not ramify in one plane only, but
develop also segmented ascending branches, which form, in the latter
species, together with the original disc, a nearly hemispherical cushion.
The entire thallus is always enveloped in mucilage.

Non-sexual propagation takes place in Coleochaete by means of
biciliated zoospores, produced either in all the cells of the thallus or only
in the terminal cells of the branches. The entire protoplasmic contents
of the mother-cell or zoosporange are used up in the production of the
zoospores, which escape from them either at the side or at the back.
'Sexual reproduction is effected by the impregnation of an oosphere formed
within an oogone by motile antherozoids, through the agency of a tricho-
gyne. The oogone is, in C. pulvinata, always constituted out of the
terminal cell of a branch, which swells up and at the same time
elongates at its extremity into a narrow hair-like trichogyne, which then

CONFERVOIDE& HETEROGAM^E

221

opens at its apex and exudes a drop of colourless mucilage. The oogone
still contains chlorophyll, and its protoplasmic contents contract into a
green oosphere. At the same time flask-shaped protuberances grow out
from adjoining cells, and these, becoming cut off from the parent-
cells by septa, are the antherids. The entire contents of each antherid
escape as a single ovoid antherozoid furnished with two very long and
slender cilia. Other species are dioecious, the antherids being produced
on different individuals from the oogones. The antherozoids probably
pass into the trichogyne through its open apex, and thence into the oogone;
but the act of impregnation has not actually been observed hitherto.
The first result of the impregnation of the oosphere is its investment

FIG. 199. — ColeochcetepulvinataK. Br. A, portion of fertile thallus(x 350); an, antherid ;og, oogone ;
h, hyaline hair ; z, antherozoid. J3, ripe oogone with its pericarp, r ( x 280). C, formation of"
carpospores within the spermocarp ( x 280). D, zoospores ( x 280).' (After Pringsheim.)

by a cell-wall of cellulose, and a considerable increase in its size. The
fertilised oogone, with the exception of the trichogyne, then becomes
surrounded by & pericarp, or cortical layer of cells ; the oogone and peri-
carp together constitute the spermocarp enclosing the fertilised oosphere
or oosperm. The spermocarp subsequently becomes further invested by
a cortex of closely applied branches resulting from the continued de-
velopment of cells at the base of the spermocarp. After the complete
development of this organ, which takes place between May and July,
the vegetative cells of the thallus disappear, and its walls assume a dark-
brown colour. The spermocarp remains dormant through the winter :.

222 ALG^E

the cortical layer is then thrown off, and the oosperm divides into several
cells or carpospores. The germinating carpospore does not give rise to a
new thallus, but to a zoospore, which gives birth to several successive non-
sexual generations propagated by zoospores, until the cycle of generations
is completed by the production of a1 sexual individual.

Mycoidea parasitica Cunn. (Trans. Linn. Soc., vol. i., 1879, P- 301)
is probably nearly allied to Coleochaete, which it resembles in the nature
of its fhallus and in its mode of reproduction. It is endophytic in the
cells of the leaves of Camellia in tropical India, inflicting great injury
on the trees. Ward (Trans. Linn. Soc., ii., 1884, p. 87) contends that
Mycoidea is in reality an epiphyllous lichen. Mobius (Ber. Deutsch.
Bot. Gesell., 1888, p. 242) regards Mycoidea, and the nearly allied
Chaetopeltis (Berth.), as more probably belonging to Chsetophoraceae.

LITERATURE.

Brebisson — Ann. Sc. Nat., i. , 1844, p. 25.
Pringsheim — Jahrb. wiss. Bot., 1860, p. i.
Kny— Ber. Deutsch. Bot. Gesell., 1884, p. 93.

ORDER 2. — (EDOGONIACE^:.

This small order, as at present constituted, comprises only two
genera — QEdogonium (Lk.) and Bulbochsete (Ag.).

CEdogonium includes several species, abundant in streams, ponds,
and tanks. TfTey are readily distinguished by the fact that they never
branch, by the cells being of small diameter and considerable length,
filled with a homogeneous dark-green protoplasm with a parietal nucleus,
and by the peculiar appearance of annular striae near one end of some
of the cells. These striae result from the appearance known as ' inter-
calary surface-growth.' Below the septum is formed an annular deposit
or cushion of cellulose; at this place the cell-wall splits, as if by a
circular cut, into two pieces, which separate from one another, but re-
main united by a zone of the cell-wall formed by an extension of the
cushion. This process is constantly repeated over a short space of the
cell-wall immediately beneath a septum, each slit being a little further
from the septum than those that preceded it ; so that these pieces, form-
ing small projections, give to the upper end of the cell the appearance
of consisting of caps placed one over the other ; while its lower end
appears as if enclosed in a long sheath consisting of the portion of the
cell-wall below the caps. This lower portion of the cell is always cut
•off by a septum from the upper cap-bearing portion. The filaments
are fixed at their base by a rhizoid to solid bodies or submerged plants.

Non-sexual propagation takes place in CEdogonium by means of
•zoospores, the formation of which affords a typical example of the process

CONFERVOIDE^E HETEROGAMsE

223

first described by A. Braun as the 'rejuvenescence' of a cell, i.e. the
transformation of the entire protoplasm of a vegetative cell into a
' primordial cell,' which subsequently invests itself with a new cell-wall,
and forms the starting-point of the life of a new individual. In some
one cell of a filament, either the terminal or some other, sometimes
even in the single cell of which a young filament is composed, the proto-
plasm contracts into a globular body which
ultimately becomes free by the rupture of the
cell-wall, by a transverse slit, into two very un-
equal halves. . When this takes place in the
terminal cell of a filament or the single cell of
a young individual, the upper smaller portion
of the cell-wall is lifted up like a lid, or even
completely thrown off like a cap. The zoospore
thus formed, which in some species is one of
the largest and most striking known, has a
nucleus, a red 'pigment-spot,' and an anterior
hyaline region, to which is attached a tuft of
cilia, visible even before its escape from its
mother-cell. At the period of escape it is still
enveloped in a transparent membrane, which,
however, it soon breaks through, and then moves
about in the water with great velocity for
perhaps half an hour, displaying at this period a
number of vacuoles. On coming to rest, the
zoospore becomes attached by its anterior hya-
line end, loses its cilia, invests itself with a
cell-wall, puts out a rhizoid from the point of
attachment, and develops into a filament with
transverse septa. From the position occupied
by the zoospore in the mother-cell, the direc-
tion of growth of the new individual must be
at right angles to that of the parent-filament.
Many of the plants which spring from zoospores
are non-sexual, producing nothing but zoospores.
(Edogonium is also reproduced by resting-spores (Wille, Bot. Gesell.
Stockholm, Sept. 26, 1883; see Bot. Centralbl., xvi., 1883, p. 215).

The sexual reproduction of (Edogonium still shows a high degree of
differentiation of the male and female elements. The antherozoids are
very similar in form to the zoospores, but much smaller, and they are
provided with a similar tuft of cilia. The antherids are cells belonging
to ordinary filaments, but shorter and not containing so much chlorophyll

cushion of cellulose which
has lengthened to the piece
of cell- wall, 7t>' in B ; c, cell-
caps (magnified).

224

ALGsE

as the rest, lying either singly among the ordinary vegetative cells, or
sometimes in groups of as many as twelve. In most species each
antheridial cell divides either horizontally or vertically into two ' special
mother-cells,' each of which gives birth to an antherozoid. The oogones
are developed either in the same filament as the antherids or not, some
species being monoecious, others dioecious. They are also frequently in
groups of from three to six. Their development always takes place out of

II.

B

FIG. 201.— I. A, filament of Q^dogonium ciliatum Hass. ;
n, zoosporange ; og, oogone with ' dwarf male,' in. B, oogone
at the moment of impregnation ; o, oosphere ; z, antherozoid ;
111, ' dwarf male.' C, CE.gemelliparum Hass. ; piece of filament
in which zoospores, z, are being formed, from which the 'dwarf
males ' are produced (x 250). II. Zoospores ; A, still within
the zoosporange ; J3, in the act of escaping ; C, free zoospore.
(After Pringsheim.)

the upper half of the lower portion of a cell provided with cell-caps at
its upper end, which has just divided, and which, directly after the
division, swells up into a spherical or ovoid form. Immediately before
impregnation the protoplasm contracts into an oosphere, containing in
one portion densely crowded chlorophyll-grains, and, at the spot opposite
to the part of the wall of the oogone which is to open, a hyaline 'receptive
spot.' The oogone opens in several ways. Sometimes an oval orifice is

CONFERVOIDEsE HETEROGAM^E

225

formed at the side, through which the colourless portion of the proto-
plasm protrudes in the form of a papilla which takes up the antherozoids.
In other cases the oogone splits in the same way as the zoosporanges,
throwing back a kind of lid ; through the lateral crevice exudes some
colourless mucilage in the form of a beak-like canal, through which
the antherozoids enter, and coalesce with the hyaline portion of the
oosphere. Immediately after impregnation the oospenn invests itself
with a cell-wall, and assumes a "brown colour, still remaining within the
oogone, which separates from the other cells of the filament, and falls
to the ground, where the oosperm passes a period of rest before germi-
nation as a hypnosperm.

FIG. 202. — Bnlbochcetc setigera Ag. B, unicellular amheridial plant. A, C, young bicellular plants.
D, mature plant with oogone, o, and ' dwarf male,' dm (x 400). (After Cooke.)

In some species the mode of fertilisation is more complicated.
Peculiar zoospores known as androspores are produced non-sexually in
special cells of the parent-plant, similar to those which give birth to the
antherozoids, only that there is in their case no preliminary formation
of 'special mother-cells.' These androspores, which closely resemble the
antherozoids in form and size, . fix themselves after swarming to a
definite spot on the female plant, on or near an oogone, producing very
small male plants, which are known as ' dwarf males ' or micrandres.
Each of these consists of two or three cells, the uppermost of which is
an antherid. This gives birth to one or more antherozoids, which escape

226 ALG^E

by the lifting up of a lid, and which impregnate the oospheres in the
usual way.

When the hypnosperm germinates after a lengthened period of rest,
it does not immediately develop into a new plant, but breaks up into
several zoospores, usually four ; these give birth to several generations of
non-sexual plants, until the cycle is completed by the production of
antherids and oogones. The sexual plants, however, especially the female
ones, produce zoospores as well.

The species of Bulbochcete (classed by some writers with Coleochsete)
are minute plants growing in fresh water, and differing from CEdogonium
in having branched filaments ; the terminal cells of the branches
ending in long hyaline bristles, which are swollen at the base. The
modes of reproduction correspond closely to those in CEdogonium.
Wittrock includes also Coleochaete and Sphseroplea among the CEdo-
goniaceae.

LITERATURE.

Braun— Verj. in der Natur, 1851 (Ray Sue. Bot. and Phys. Mem., 1853).

De Bary — Ueber CEdogonium ur Bulbochaete, 1854.

Pringsheim — Jahrb. wiss. Bot., 1858, p. I.

Carter— Ann. and Mag. Nat. Hist., 1858, p. 29.

Juranyi — Pringshein/s Jahrb. wiss. Bot., 1873, p. I.

Wittrock — Prodr. Monogr. CEdogoniearum, 1874.

Wille — Pringsheim's Jahrb. wiss. Bot., 1887, pp. 443 and 454.

ORDER 3. — SPH^EROPLEACE^.

This order comprises at present the single species Sphceroplea
annulina Ag., the simplest of the class, found occasionally on flooded
fields. The filaments are cylindrical and unbranched, and are composed
of cells which vary in their comparative length and breadth to an extra-
ordinary degree ; sometimes the length will hardly exceed the breadth,
while in other cases it may be as much as ninety times as great. The
transverse cell-walls are of great thickness, their surface is irregularly
wavy, and they swell out here and there into great ' beams ' and excres-
cences of cellulose from both the lateral and longitudinal walls. During
the development of these septa, orifices are formed in them for the
passage of the antherozoids. The cells contain a large number of
chromatophores and starch-grains, as well as, when mature, a consider-
able number of small nuclei.

The sexual reproductive elements are oospheres and antherozoids,
formed in different cells of the same filament, which may therefore be
regarded as rudimentary oogones and antherids. A filament may consist of

CONFERVOIDE& HETEROGAM&

227

only two cells, and then one becomes an oogone, the other an antherid.
When the number of cells is greater, the oogones and antherids some-
times alternate with one another, but this is not always the case. The
contents of an oogone break up into several spherical oospheres, each
of which is characterised by a hyaline speck or ' receptive spot.' The
antherozoids are produced in extraordinarily large numbers by the
breaking up of the contents of an antherid which had previously assumed
a brownish red colour. They are furnished with two long slender vibra-
tile cilia, and enter the oogones through the orifices in the transverse
walls already mentioned ; in their passage they go through remarkable

FIG. 203. — Portion of filament of
Sph&roplea annulina Ag. ;
upper cell containing oospheres
and antherids, lower cell an im-
pregnated oosperm ( x 500).
(After Cohn.)

FIG. 204. — 6". anmilina. A, young unicellular plant
( x 900) ; £, portion of mature filament, showing
thick transverse wall and two nuclei, n (x 800).
(After Rauwenhoff.)

changes of form. The fertilised oospore, or oosperm, clothes itself with
a thick cuticularised warty membrane, and its contents turn a brick-
red colour. It usually hibernates within the oogone in the form of a
hypnosperm ; in the spring its contents break up into three or four
zoospores, each of which develops into a slender thread consisting at first
of a single fusiform cell which displays no distinction of base and apex,
each extremity being elongated into a flagelliform point. The oosphere
may also break up into zoospores without previous impregnation.

Probably nearly allied to Sphaeroplea, but of somewhat uncertain
position, is Cylindrocapsa (Reinsch) (Cienkowski, Mel. Biol. Acad.
St. Petersbourg, 1876, p. 534), the mode of reproduction of which is

Q 2

228 'ALG^E

heterogamous. In other respects it indicates affinity with Ulothrix, and
is surrounded by a remarkably thick lamellated gelatinous envelope. It
is made by some writers the type of a distinct family, the CYLINDRO
CAPSACE^E.

LITERATURE.

Cohn— Ann. Sc. Nat., v., 1856, p. 187.
Heinricher - Ber. Deutsch. Bot. Gesell., 1883, p. 433.

Rauwenhoff— Rev. Internat. Sc. Biol., 1883, p. 176; and Arch. Neerl. Sc. Exact,
et Nat., 1887, p. 91.

Class XII.— Fucaceae.

This family — adopting the limits first proposed by Thuret — consists
of a small number of genera of large olive-brown seaweeds distinguished
by their mode of sexual reproduction, and by the entire absence,
throughout the class, of zoospores, or indeed of any kind of non-sexual
spore.

The thallus or ' frond ' is often several feet in length, cylindrical or
flattened, or, in Himanthalia (Lyng.), cup-shaped, of a cartilaginous
texture, and is attached to the sea bottom by a branched rhizoid or
attachment- disc. This organ is altogether superficial, and has no function
in the absorption of food-material, like the root of higher plants. It
is formed entirely of filaments originating from the stipe or stem. In
some species detached branches have the power of maintaining their
existence, and even multiplying for an indefinite period, floating on the
surface. Nearly all the species are perennial. Although the thallus
does not display the same amount of external differentiation into ' stipe '
and * frond ' as some of the Laminariaceae, the differentiation of internal
tissues is quite as great. In the centre of the thallus is a medullary
system composed of elongated cells, and surrounded by a cortical system
of shorter nearly isodiametrical cells ; there is only a very rudimentary
development of epiderm. The thallus increases in thickness by the
radial division of the outermost rows of cells or hyphce of which the
cortex is composed. Growth in length is entirely apical, taking place,
according to the most recent observations, by the segmentation of a
single well-marked four-sided apical cell, which may be seated, as in
Fucus furcatus (Ag.), at the base of a depression at the apex of the
frond. Grabendorfer states (Bot. Zeit., 1885, pp. 609 et seq.} that in
Durvillsea (Bory) there is no apical growing point. The thallus of the
Fucaceas always branches dichotomously and monopodially, the branches
lying, when not disturbed, in a single plane. In the more highly

FUCACE^E

229

FIG. 205. — Himanthalialorea. Lyng. (natural
size). (After Hauck.)

FIG. 206. — Halidrys siliqnosa Lyng.
(natural size). (After Hauck.)

230

developed genera, such as Sargassum (Ag.) and Durvillaga, there is a
more or less advanced differentiation of lamina or leaf from stipe or stem ;
and the ' leaves ' are even arranged spirally and furnished with a rudi-
mentary midrib.

The cell-wall often consists of two distinct layers, an inner firm
compact but thin layer, and an outer gelatinous one which swells greatly
in fresh water, filling up the intercellular spaces, and causing the
slimy character which the Fucaceae commonly assume after they have
lain for some time in fresh water. The cells contain chlorophyll ; but
the green colour is in all cases entirely masked by a pigment of a brown
or olive colour, which can be extracted from the dead plant by cold fresh
water. The nature of this pigment has been investigated by Millardet,
Rosanoff, Sorby, Schiitt, and others. According to Millardet, an olive -
green alcoholic extract may be obtained from quickly dried and powdered
specimens. If this is then shaken up with double its volume of benzine
and allowed to settle, the upper layer of benzine is coloured green by
having taken up the chlorophyll, while the lower alcoholic layer is yellow,
and contains phycoxanthin in solution. Thin sections of the thallus,
after complete extraction by alcohol, still yield a reddish brown substance
which in fresh cells adheres to the chlorophyll-grains, but can be dis-
solved out with cold water, especially if the frond be first reduced to
powder. To this reddish brown substance, the spectrum of which has one
absorption band between E and F, Millardet gives the name phycophczin.
Schiitt states that the spectrum of phycophaein has no characteristic
absorption bands, but a regular increase of absorption from the red
towards the blue end. He proposes to limit the term phycophaein to
the portion soluble in water, and phycoxanthin to that soluble in alcohol,
while the entire compound pigment of the Fucaceae and Phaeosporeae
he would call phceophyll. Sorby applies the term fucoxanthin to the
principal colouring matter of the olive-green seaweeds (Fucaceae and
Laminariaceae). It is soluble in bisulphide of carbon, imparting to it a
beautiful amber colour ; its spectrum shows two obscure absorption-
bands in the yellow. Hick (Journ. of Bot, 1885, pp. 97 and 354) has
detected continuity of protoplasm in several species of Fucus, both in
the cortical layers and in the central medullary tissue. The intercom-
munication of the protoplasmic contents of contiguous cells is also
effected, as in ;the Laminariaceae (see p. 244), through structures of the
nature of sieve-plates.

In many of the Fucaceae air-bladders are formed in the frond by the
hollowing out of large cavities in the interior of the tissue, which serve
to float the frond in the water, and to aid in the process of fertilisa-
tion. These are especially noticeable in the common * bladder-wrack '

FUCACE&

FIG. 207.— a, Ficcus vesicnlosus L. ; t>, F. terrains L., with their attachment-discs united in growth
(natural size). (After Ktitzing.)

*Q4

232

ALG^E

of our coasts, Fucus vesiculosus (L.), and in other species of the genus.
In the 'gulfweed' of the 'Sargasso Sea' (Sargassum bacciferum, Ag.)
these bladders are spherical, and are elevated on pedicels above the
surface of the frond, giving them the appearance of berries (fig. 211). In
Halidrys (Grev.) they are ovoid, segmented, and pod-like in appearance
(fig. 206).

The only reproductive organs of the Fucaceae are sexual, antherids
and oogones. Both kinds are formed in globular cavities known as con-
ceptacles, which are either distributed uniformly over the thallus, or are
congregated in particular portions of it, which are then known as re-
ceptacles. These are always either the terminal portions of branches,
or are in the parts provided with air-bladders, so as to be elevated above.

.FiG. 208. — Section of male conceptacle of F. vesicnlosus, clothed with branched
hyphae bearing the antherids ; o, ostiole (magnified).

the surface of the water for the purpose of fertilisation. In Fucus (L.)
the receptacles constitute the warty extremities of the branches ; in
Himanthalia (Lyng.) the whole of the long whip-shaped stem which pro-
ceeds from the cup-shaped thallus is a receptacle (fig. 205) ; in Sargassum
(Ag.) they pccupy distinct fertile branches. In some species there are
separate male sundfema/e conceptacles, and then they are always dioecious ;
in other species antherids and oogones are contained in the same con-
ceptacle, the female organs occupying the lower, the male organs the
upper part of the cavity. There are also sometimes cavities of precisely
similar structure, but producing no sexual organs, which may be
degraded or aborted conceptacles. Both the fertile and barren con-
ceptacles are clothed internally by a dense weft of loose hyphae, which

FUCACE^ 233

are a prolongation of those of which the thallus is composed, and
frequently project, through the mouth or ostiok of the conceptacle, into
the surrounding water. When infertile these hyphae are known as
paranemes or paraphyses. In the male conceptacles they are usually
branched, unbranched in the female. Both the barren and fertile con-
ceptacles are always first formed in the neighbourhood of the growing
point, the cavity originating from the absorption of a row of cells at
right angles to the surface.

The antherids are produced on lateral branches of trie hyphae in the
male or in the upper part of bisexual conceptacles. Each consists of
an ovoid thin-walled or sometimes double-walled cell, the abundant
protoplasm of which breaks up into a number (usually sixty-four) of

FIG. 209. — Section of female conceptacle of F. vesiculosus, clothed with unbranched
hyphae bearing the oogones ; o, ostiole (magnified).

minute antherozoids, pointed at one end, with a pair of cilia of unequal
length placed laterally below the beak-like apex, and contains an orange-
red pigment spot and a nucleus. The olive-brown oogones are developed
from unbranched hyphae in the female, or in the lower part of bisexual
conceptacles. These fertile hyphae are at first unicellular, and are
bounded at the base by a septum ; the single cell subsequently divides
into a basal pedicel-cell, and an upper portion, which swells into a
spherical or ellipsoidal form, the oogone, filled with protoplasm coloured-
brown by phycophaein, and always provided with a wall composed of
two layers. Either the whole of the contents of the oogone contract
into a single oosphere, or it divides into two, four, or eight oospheres,
each with its own nucleus. Impregnation always takes place outside

234

ALG/E

the conceptacle. The outer layer of the double wall of the oogone
bursts, the inner layer still continuing to enclose the oospheres in a thin
bladder-like membrane. In this form they escape from the conceptacle
through the ostiole into the surrounding water, where the remaining
membrane is also absorbed. In the meantime the antherids have become
detached, the inner layer of the double cell-wall having burst through
the outer layer, and collect in large numbers before the ostiole of the
female or of the bisexual conceptacles, forming orange-red masses which
are often caughf by the paraphyses which hang out from the ostiole, or
are left on the shore at low tide. On the return of the tide, or after
they have remained for a time entangled in the paraphyses, the inner
membrane of the antherid also becomes absorbed, and the antherozoids
escape at the same time that the oospheres become released from their

FIG. 210. — F. vesiculosus. A, branched hypha bearing antherids (x 160). B, antherozoids (x 330).
/, oogone, Og, contaiping eight oospheres ; /, unbranched hyphae. //, oospheres preparing to
escape ; a, outer, z', inner layer of cell-wall of oogone. ///, oosphere surrounded by antherozoids.
IV, V, stages in germination of oosperm (x 160). (After Thuret.)

enveloping membrane. The antherozoids frequently collect round the
oospheres in such numbers that the motion of their cilia imparts to the
comparatively very large passive oosphere a rolling movement which lasts
for about half an hour, when they become absorbed into it and impreg-
nate it. The oospheres are receptive over their whole surface ; and,
although it has been calculated that the bulk of an oosphere is equal to
that of from 30,000 to 60,000 antherozoids, an oosphere can apparently
be fertilised by a single antherozoid. In this family the mode of repro-

FUCACE^E

235

duction consisting in the impregnation of a passive oosphere by motile
antherozoids attains its highest development among Algae. The.
antherozoids retain their motility and vitality for from one to three days.
The oospheres will show signs of a rudimentary germination even when
unfertilised, but in that case the germ soon perishes. Thuret succeeded
in obtaining a hybrid Fucus by impregnating the oospheres of F. vesicu-
losus (L.) by the antherozoids of F. serratus (L.).

A short time after impregnation the oosperm invests itself with a
cell-wall, fixes itself to some other body, and begins to germinate with-
out any intervening period of rest. The first transverse division of
the young germinating filament is followed by others in various direc-
tions, so that a solid
mass of pseudo-
parenchyme is at
length formed, fixed
to the bottom by a
root-like rhizoid.

The Fucaceae
constitute a small
and well - marked
family of seaweeds,
united by some sys-
tematists with the
Phaeosporeae, or at
least with the Lami-
nariaceae, to make
up the Fucoideae
of Agardh, or the
Melanospermese of
Harvey. They are,
however, well dis-
tinguished by their
mode of reproduc-
tion. The family
is represented in
Britain by the genera
Halidrys (Grev.),
Cystosira (Ag.), Pycnophycus (Ktz.), Fucus (L.), Ascophylla (Stackh.),and
Himanthalia (Lyng.), and includes also the exotic genera Sargassum (Ag.),
Pelvetia(Dcne.), Durvillsea (Bory), Splachnidium(Grev.), and a few others.
Although the number of native British species described by Harvey is only
thirteen, some of these occur in such vast quantities that the Fucaceae

FIG. 2ii.— The gulfweed, Sargassum bacciferum Ag.
(natural size).

256 ALGJZ

cover a larger amount of surface of tidal rocks than all the other sea-
weeds together. Among these may be especially mentioned the familiar
bladder-wrack, Fucus vesiculosus, so abundant on all our coasts. The
well-known gulfweed, Sargassum bacciferum, distinguished by its berry-
like air-bladders, a native of warmer seas, is sometimes thrown up
on our shores, where it is carried by the gulf-stream. It very rarely
fructifies ; detached pieces, buoyed up by the air-bladders, being able
to retain their vitality for an indefinite length of time. An enormous
floating mass of this seaweed, consisting entirely of detached pieces,
is said to cover an area of 200,000 square miles in the Atlantic,
about lat. 20-25° N. and long. 40° W., where it has maintained itself
writh but little shifting since the time of Columbus, affording a home
and breeding-place for countless numbers of marine animals. The
family is, however, chiefly European ; a large proportion of the species
live only in shallow water, being exposed at every ebb-tide, or only
at neap-tides, when fertilisation takes place. The distinctions be-
tween the different genera are made to rest on the disposition of the
air-bladders and conceptacles, and on the more or less distinct differen-
tiation of the leaf-like organs. The frond of Splachnidium is partially
gelatinous. The structure of that of Durvillaea, one of the largest of
seaweeds, is very beautiful, being permeated by very large and regular
cavities resembling a honeycomb. Together with the Laminariaceae, our
native Fucaceae are largely used in the manufacture of kelp, though not
to the same extent as formerly, and as a source of iodine ; they are also
employed by farmers as a manure for their fields. On the coast of
Chili the poorer classes use a species of Durvillaea for food, and a soup
is made from it which is mucilaginous and sweet.

LITERATURE.

Agardh — Species, Genera, et Orclines Fucoidearum, 1848.
Thuret— Ann. Sc. Nat., 1854, p. 195.
Pringsheim— Member. Berlin. Akad. Wiss., 1855, p. 133.
Rosanoff— (Pigment) Mem. Soc. Sc. Nat. Cherbourg, 1867, p. 145.
Millardet — (Pigment) Comptes Rendus, Ixviii., 1869, p. 462.
Kraus et Millardet — (Pigment) Mem. Soc. Sc. Nat. Cherbourg, 1870, p. 23.
Kny— Bot. Zeit., 1872, p. 699; and 1875, P- 45°-
Sorby — (Pigment) Proc. Roy. Soc., 1873, PP- 455 et seq.
Reinke— Jahrb. wiss. Bot., 1876, p. 399 ; and Bot. Zeit., 1877, p. 651.
Rostafmski — Beitr. z. Kenntniss d. Tange, 1876.
Thuret & Bornet— Etudes phycologiques, 1878.
Kuntze — (Sargassum) Engler's Bot. Jahrbuch, 1880, p. 191.
Bower — (Conceptacle) Quart. Journ. Microsc. Sc. , 1880, p. 36.
Bnrthairi TV Cystoseiren (Fauna u. Flora Golfes Neapel), 1883.
Hanstein— Sitzber. Phys.-Med. Gesell. Wiirzburg, 1884, p. 104; and Arbeit. Bot.
Inst. Wiirzburg, 1885, p. 289.

FUCACE^E 237

Dodel-Port — (Cystosira) Biolog. Fragmente, pt. i., 1885.
Behrens— (Fertilisation) Ber. Deutsch. Bot. Gesell., 1886, p. 92.
Schiitt — (Phycophsein) ibid. , 1887, p. 259.
Woodworth— (Apical Cell) Ann. of Bot., i., 1888, p. 203.

Class XIII.— Phaeosporeae.

The Phaeosporese or Phaeozoosporeae form, together with the Fucaceae,
the whole of the olive and brown seaweeds of the globe, formerly
grouped together under the names Fucoideae, Melanosporeae, or Melano-
spermese ; but of many the history of development is at present but
imperfectly known ; and when this is ascertained more fully, they may
possibly be separated into groups having but little affinity with one
another. A number of the Phaeosporeae are epiphytic, and a few
parasitic on other seaweeds ; a very few grow in fresh water.

The ordinary mode of multiplication of the Phaeosporeae is, so far as
is known at present, non-sexually by means of zoospores* which occur in
all the orders except the most aberrant groups — the Dictyotaceae, where
they are replaced by motionless spores, and the Syngeneticae. In the
Sphacelariaceae there is another mode of non-sexual propagation by
means of gemmae or propaguks. Each zoospore has a large red pigment-
spot and two cilia, a longer one pointing forwards and a shorter one
directed backwards. They differ from those of the green Algse, such as
the Confervoideae, in the lateral insertion of the cilia at the base of the
colourless apex. They are produced in zoosporanges, which are either
external, when they are usually the terminal cells of short branches, or are
imbedded in the thallus, in which case they are frequently collected
into definite groups or sort, and are interspersed with barren filaments
or hyphae, known as paranemes or paraphyses. These are often swollen
and club-shaped at their apex ; the zoosporanges sometimes spring as
lateral branches from similar filaments. The zoosporanges are of two
kinds, unilocular and multilocular (the 'oosporanges' and 'trichospo-
ranges' respectively of Thuret). The former are comparatively large,
nearly spherical, ovoid, or pear-shaped, and their contents break up directly
into a large number of zoospores which escape through a terminal or
lateral opening. The latter kind have somewhat the appearance of jointed
hairs, and are segmented in the transverse direction only ; or less often
are more like the unilocular zoosporanges in form, but are divided
internally by both transverse and longitudinal septa. Each cell gives
birth to a single zoospore ; and these either escape each separately

238

ALGsE

from its own mother-cell, or an opening is formed at the apex of the
sporange through which all the zoospores escape after dissolution of the
septa. The zoospores are in all cases imbedded in mucilage ; no differ-

FIG. 212. — Giraudia sphacelarioid.es D. and S. a, upper portion of thallus (x 250) ; b, lower portion
with multilocular sporanges ( x 250). (After Areschoug.) c, portion of filament with unilocular
sporanges ( x 600). (After Hauck.)

PH.-EOSPOREAL 239

•ence is observable in size or form between those produced in the two
kinds of sporange, but those from the unilocular sporanges appear
in all cases to germinate directly, while those from the multilocular
sporanges are sometimes zoogametes with sexual functions. The two
kinds of sporange may be borne on the same or on different indi-
viduals j in the former case they are occasionally developed at different
times. In certain orders or groups one or the other kind is altogether
wanting.

The various modes of sexual reproduction known in the Phseosporese
present a most interesting gradual transition from the conjugation of
equivalent motile zoogametes to the impregnation of a quiescent
oosphere by motile antherozoids. In Ectocarpus (Lyng.), Giraudia (D.
and S.), and Scytosiphon (Ag.) conjugation takes place between swarm-
cells from the multilocular sporanges, which are to all appearance
exactly alike ; but a slight sexual differentiation is exhibited in the fact
of one of them coming to rest and partially losing its cilia before conju-
gation takes place. In Cutleria (Grev.) and Zanardinia (Nard.) the
differentiation is more complete. The male and female swarm-cells are
produced either on the same or on different individuals ; the latter are
much larger than the former, and come perfectly to rest, entirely losing
their cilia before being impregnated by the former. In Dictyota (Lmx.)
the differentiation is carried still further, and the female reproductive
bodies are from the first motionless masses of protoplasm not provided
with cilia. In Dictyosiphon (Grev.) (Punctariaceae) a different kind of
conjugation has been observed.

The degree and mode of development of the thallus Differ very
widely within the class. A few 'species of Ectocarpaceae, belonging to
the genera Streblonema (Derb.) and Ectocarpus (Lyng.), are microscopic.
Some of the Mesoglceaceae and Ralfsiaceas are small seaweeds epiphytic
on those of larger growth, with a flat radiating thallus reminding one of
Coleochaete. In some of the Ectocarpaceae the thallus consists of
simple branched or unbranched filaments resembling those of the
Confervaceae. In the Sphacelariaceae each branch is composed of a
row of larger central surrounded by a layer of smaller cortical cells, all
originating from a large uncorticated apical cell. In the Cutleriaceae
filaments of cells become separated from the margin of the thallus, the
basal portions of which are coalescent into a solid tissue, the increase in
breadth of which is due to the branching of the filaments. The
Laminariaceas include, in the genera Alaria (Grev.), Laniinaria (Lmx.),
Macrocystis (Ag.), and others, the most gigantic of marine organisms,
in which the thallus or ' frond ' is to a certain extent differentiated
externally into rhizoid or organ of attachment, stipe or stem, and

240

ALGsE

leaves. We have here also an approach to
the internal differentiation of tissues which
occurs in the higher plants, though this is
not so strongly displayed as in the Fucacese.
In Macrocystis, however, the lamina of the
frond may be divided into an epidermal layer,
cortical parenchyme, and medullary tissue.
Sieve-hyphae occur in all the genera, and in
Macrocystis and Nereocystis (Post.) true sieve-
tubes with sieve-plates and deposit of callus.
Through the perforations in the sieve-plates
HickQourn. Bot, 1885, p. 356) and Willehave
detected the passage of strings of protoplasm
connecting the cells with one another. The
protoplasts of the cortex in Laminaria digitata
(Lmx.) are described by Hick as rhizopod-
like bodies spreading in such a way that the
cells of each layer are brought into connection
both with one another and with those of adja-
cent layers. The cells of the Phaeosporeae con-
tain a carbohydrate closely resembling starch,
but differing in not being coloured
blue b)ttodine, and an olive-brown
pigment soluble in cold fresh water
identical with the phycophmn of
the Fucaceae. The tissues both

(I/.

241

of the Laminariaceae and of other large marine Algae belonging to other
groups display remarkable elasticity or other properties to enable them
to resist the traction of the waves. In the larger species the frond is
buoyed up by air-bladders.

Janczewski describes the occurrence in the class of three distinct
modes of growth, viz. — (i) The
thallus and all its ramifications
terminate in a generative apical cell
which divides in a direction parallel
to its base, and thus gives birth to a
series of segments. This occurs in
the Sphacelariacese and in Dictyo-
siphon, but is the least common
mode. (2) By peripheral growth,
i.e. the marginal cells of the thallus
are the youngest, and are more or less
united into a generative peripheral
zone (Myrionema, Grev., Leathesia,
Gray, Ralfsia, Berk.). (3) By in-
tercalary growth. This is much the
most common mode, and there are,
again, three modifications of it, -viz.
— i. The thallus terminates, when
young, in one or more hairs, the
common growing point of the
thallus and of the hairs being situ-
ated at their point of junction (Ecto-
carpus, Desmarestia, Lmx., Carpo-
mitra, Ktz., Cutleria, Sporochnus,
Ag.). 2. The thallus is differen-
tiated into three 'organs'— frond,
stipe, and rhizoids ; the growing point from which the stipe and frond
originate is common to these two organs, while the rhizoids increase by
apical growth (Laminariaceae). 3. The absolutely undivided thallus is
regenerated from the growing point situated at the base of the frond
(Scytosiphon, Chorda, Punctaria, Grev., Asperococcus, Lmx.).

LITERATURE.

Magnus — Festschr. Gesell. naturf. Freunde, Berlin, 1873.

Areschoug— Bot. Notis., 1873.

Gobi— -Bot. Zeit., 1877, p. 425.

Reinke — Ibid. , p. 441.

Thuret & Bornet— Etudes Phycologiques, 1878.

FIG. 214

— Lessonia fuscescens Bory
(greatly reduced).

242

ALG.E

Falkenberg — Mittheil. Zool. Stat. Neapel, 1878, p.

531-

Wille— Bot. Sallsk. Stockholm, Nov. 19, 1884 (see Bot.
Centralbl., xxi., 1885, pp. 282 et seq.).

In so many of the Phaeosporeae the life-
history is at present but imperfectly known,
and different authors differ so widely as to the
best characters to be employed in classifica-
tion, that no attempt is here made to arrange
into orders all the known forms. A de-
scription is given only of the best-marked
groups.

The LAMINARIACE^: include many of the
largest of the brown seaweeds of both warmer
and colder seas; in the southern hemisphere
they form dense submarine forests of gigantic
size, frequently making even deep water impass-
able for boats, and forming a home for myriads
of marine animals ; the individual ' fronds '
sometimes attaining a length of several hundred
feet. The thallus.is coriaceous, is not articu-
lated, and is usually attached to the sea-bottom
by rhizoids or root-like organs of attachment,
or less often by a discoid expansion, from
which springs a tough cylindrical stipe or stem,
the tissue of which is more or less differentiated
into a medullary portion, an internal and an
external cortical portion, and an epidermal
portion, the cells of which are coloured brown
by phycophaein. It increases in length by
intercalary growth at the junction of the stipe
and lamina. Although most of the larger
species are perennial, Areschoug states that
even the largest species of Nereocystis (Post.)
are annual. In others the stem increases in
girth from year to year, attaining sometimes
the thickness of a man's thigh. In Chorda
, . filum (Stackh.). one of the commonest of our

FIG. 215. - - Laminanasaccharina ^ /'

Lmx., with rhizoids. j, por- seaweeds, the entire thallus is cylindrical and

tion of frond which produces . ....

zoospores (reduced j). (After whip-like, as much as forty feet in length,

Reinke.)

FIG. 217.— Longitudinal section of Macrocystis pyrifera, showing
sieve-tubes, /, and sieve-plates, s, with callus (x 300). (After
Oliver.)

FIG. 216. — Chorda, filum Stackh. a, uppermost and lowermost portion of frond (natural size); bt
-transverse section, showing differentiation into cortical and epidermal layers (x 200). (After Hauck.)

R 2

244

«

and is septated by transverse divisions; it is constantly dying off at the
apex, the growing point lying at its base immediately above the rhizoids.
More often the upper part of the thallus is differentiated into branched
annual 'leaves' of cartilaginous texture, usually flat, but sometimes
tubular, and often ribbed. Lessonia (Bory) grows erect to a great
height, and resembles a branching tree with pendent leaves two or three
feet long (fig. 214). In Thalassiophyllum (Post.), Agarum (Grev.), and
other genera, the frond is beautifully perforated ; these perforations are
formed from hollow conical papillae by which the frond is first covered ;
the tissue diminishes at the apex of the cones, then bursts, and the
opening enlarges as the frond grows. In Macrocystis (Ag.) the stalk-like
base of each branch of the frond is swollen out into a large pear-shaped
air-bladder. In Nereocystis the air-bladder is barrel-shaped, six or
seven feet in length, and crowned with a tuft of fronds. Sieve-hyphae or
trumpet-hyphae with imperfect sieve-plates occur in all the genera ; and
Oliver has discovered in the comparatively weak stems of Nereocystis
and Macrocystis a structure almost identical with that which occurs in
the weak climbing stems of many Flowering Plants, true sieie-tubes with
perfectly formed sieve-plates both in the septa and in the longitudinal
cell-walls, provided with a true callus-formation (fig. 217).

Zoosporanges of one kind only— the uniloQular — are at present known
in the Laminariaceae ; these are distributed uniformly over the surface
of the thallus or are collected into sort, and are interspersed with simple
unsegmented club-shaped sterile hairs or paraphyses. Of the mode in
which the zoospores act as propagative organs very little is known.
Areschoug has observed the germination of the zoospores of Chorda
tomentosa (Lyng.) after the coherence of two of them by their beaks ; but
he does not regard this as a true process of conjugation. Gardiner be
lieves that he has detected the conjugation of zoospores in Alaria (Grev.).

Along with the Fucaceae, the Laminariaceae are one of the most im-
portant commercial sources of iodine. The species of our own shores
are employed in the manufacture of kelp. Alaria esculenta (L.) is used
by the inhabitants of Scandinavia and Iceland as an article of food, as
also are Laminaria digitata (Lmx.) and other species under the name of
' tangle.' The stems of the last-named species are employed for surgical
purposes ; those of Ecklonia (Hornem.) and others of the larger genera
are used as siphons and for making fishing-nets.

LITERATURE.

Reinke — Pringsheim's Jahrb. wiss. Bot., 1876, p. 317.
Areschoug— Observ. Phycol., iii., 1875, iv-> l883> v-> 1884 ; and ActaSoc. Sc. Upsa-

liensis, 1875, 1883, and 1884.
Will— ( Macrocystis) Bot. Zeit., 1884, pp. 801 et seq.

PH^EOSPORE^E

245

Wille— (Sieve-tubes) Ber. Deutsch. Bot. Gesell., 1885, p. 29.
Gardiner— (Conjugation of Zoospores) Proc. Cambr. Phil. Soc., 1886.
Humphrey— (Agarum) Proc. Amer. Acad. Sc., 1886, p. 195.
Oliver — (Sieve-tubes) Ann. of Bot., i., 1887, p. 95.

In the PUNCTARIACE^E, SPOROCHNACE^E, and SCYTOSIPHONACE^E —
the limits of which orders are not settled by systematists — the structure
of the thallus varies greatly. In Punctaria (Grev.) and Phyllitis (Ktz.)
it is flat and leaf-like, from one to six layers of cells in thickness; in
other genera it is slender, cylindrical, erect, and more or less branched,
the main axis being either solid or hollow, and consisting of a
pseudo-parenchymatous tissue, in which the outermost or the two or
three outer rows of cells are much smaller than the inner ones. In

FIG. 218. — Asperoccccns bnllosus Lmx. a, natural size (after Bornet) ; £, portion of surface with
sorus(x 100) ; c, transverse section through thallus and sorus ( x 100). (After Kiitzing.)

Dictyosiphon (Grev.) the 'frond' branches into delicate hairs. In
Arthrocladia (Duby) the branches are arranged in delicate whorls. In
Scytosiphon (Ag.) the thallus is elongated, cylindrical, and unbranched,
but constricted at intervals, and resembles that of Chorda in habit. In
other genera, as Asperococcus (Lmx.) and Hydroclathrus (Bory), it is
hollow and bladdery. In most of the genera both kinds of zoosporange
are known, while in others one or the other has not yet been . detected.

246

*

Their arrangement, on which the delimitation of the orders is largely
made to rest, varies greatly. They may be collected into wart-like sori
on the surface of the thallus, appearing sometimes like dark dots uni-
formly distributed, or they may spring from the branches. In Sporochnus
(Ag.) the unilocular sporanges are collected into a peculiar receptacle

FIG. 219. — Sporochnus pedunculatus Ag. <z, natural size ; l>, c, receptacle containing
zoosporanges ; d, unilocular zoosporange ( X 100). (After Kiitzing.)

consisting of pear-shaped swellings near the extremity of the branches,
composed of a dense mass of filaments on which the sporanges appear
as lateral branches. Very little is known of the further history of the
zoospores. In Scytosiphon lomentarium (Ag.) Berthold ('Mittheilungem
Zool. Stat. Neapel,' ii., 1881) has observed conjugation of the swarm-

PH^EOSPORE^E

247

spores contained in the multilocular sporanges, which must therefore
be regarded as zoogametes, and the phenomena are the same as in
the Ectocarpaceae. Areschoug (' Observ. Phycol., iii., 1875) describes
a remarkable kind of conjugation — altogether peculiar as far as the
brown seaweeds are concerned— in the swarm-spores of Dictyosiphon
hippuroides (Lyng.), somewhat resembling that in the Conjygatae. Two,
or sometimes three, of the zoogametes cohere by their apices, and the
contents slowly pass entirely into one of them, but only after they have
come to rest. Both then become invested with a thin coat of cellulose,
and the one into which the endochrome has passed, which may be called
the female element, subsequently germinates. In other cases the con-
jugating zoogametes put out conjugating tubes not unlike those of the
Zygnemaceae. Some of the zoospores also germinate without conju-
gating.

LITERATURE.

Reinke — Pringsheim's Jahrb. wiss. Bot., 1878, p. 362.

The MESOGLCEACEJE or Chordariaceae (Myrionema, Grev., Leathesia,
Gray, Chordaria, Ag., Mesoglcea, Ag.,
&c.) are seaweeds with a gelatinous
or cartilaginous thallus of hemisphe-
rical or cylindrical outline, variable in
size, and forming small gelatinous or
slimy cushions or branching tufts on
larger seaweeds. Each filament is com-
posed of a vertical central row of cells,
surrounded by a ' cortex ' of radial rows
at right angles to the central row. On
these cortical rows are placed the zoo-
sporanges, which are both unilocular
and multilocular, concealed within the
periphery of the 'frond.' Nothing is
known of the conjugation of the
swarm-spores; they appear to germi-
nate directly, giving rise to a creep-
ing branched filament, from which the ascending axes subsequently rise.

FIG. wo.—Chordaria

jlagelliformis Ag.
Transverse section through thallus, with

unilocular zoosporanges (x 200).
Kutzing.)

(After

The ECTOCARPACE/E constitute an ill-defined group of small, occa-
sionally microscopic, marine (Elachista, Duby, Ectocarpus, Lyng.,
Giraudia, Derb.) or rarely fresh-water (Pleurocladia, Br.) Algae, usually

248

ALG^E

attached in tufts to larger algae, and resembling in habit the fresh-water
Confervaceae. The thallus consists of segmented more or less branched
filaments, either composed of a single row of cells or corticated. The
growing point of the filament does not lie at its apex, but at the extremity
of a basal portion, the true thallus, the terminal hair-like portion being

deciduous. The zoosporanges are of
both kinds, and are either external
and stalked, or are ordinary cells
of a filament, whether terminal or
intercalary. Multilocular sporanges
are sometimes produced on the

FIG. 221. — Ectocarpus investiens Hauck,
epiphytic ' on Gracilaria compt essa
(x 250). (After Burnet.)

FiG. aa-,2. — Conjugation of zoogametes of
Ectocarpiis siliculosus Ktz. /, a-f, female
zoogamete, gradually losing its cilia. //,
male zoogametes swarming round female zoo-
gamete ///, ct-e, stages in the coalescence
of the male and female zoogametes (x 790).
(After Berthold.)

same individual as the uhilocular, but at a later period. The swarm-
cells which escape from the unilocular sporanges are non-sexual zoospores,
germinating directly after coming to rest, and investing themselves with
a cell-wall. Those contained in the multilocular sporanges all escape
through a single terminal opening, and partake to a certain extent of
sexual properties, or become under certain conditions zoogametes.

PH.EOSPOREsE 249

Goebel has observed their conjugation in Giraudia sphacelarioides (Derb.)
and Ectocarpus pusillus (Griff.), Berthold in E. siliculosus (Ktz.). The
process is thus described by Berthold. There is no apparent difference
between the male and female 'gametes. The female swarm-spores lose
their cilia and come to rest first. They appear to be in a receptive
condition only for a few minutes, during which time they seem to exer-
cise an attractive force on the male gametes, which swarm round them
until coalescence takes place. The impregnated gamete immediately
clothes itself with a cell-wall, and proceeds to germinate. If unim-
pregnated it will still germinate, though not so rapidly ; as also do the
male swarm-spores which fail to conjugate ; but in this case the resulting
hew individuals are weakly, and soon perish. This process in the
Ectocarpaceae may be regarded as the first stage between the conjuga-
tion of equivalent zoogametes and the impregnation of a passive oosphere
by an antherozoid. Wright (Trans. Roy. Irish Acad., 1877, p. 15) has
•detected on an Ectocarpus a parasitic Chytridium, the zoospores of
which he believes to have been mistaken for sexual organs of the host.

LITERATURE.

Askenasy— Bot. Zeit., 1869, p. 785.

Janczewski — Mem. Soc. Sc. Nat. Cherbourg, 1875, P- 97-
Goebel— Bot. Zeit, 1878, pp. 177, 193.
Berthold - Mittheil. Zool. Stat. Neapel, ii., 1881.

The TILOPTERIDE^: (Tilopteris, Ktz., Haplospora, Kjellm.) are a
small and ill-defined family, probably nearly related to the Ectocarpaceae.

The SPHACELARIACE^: (Sphacelaria, Lyng., Stypocaulon, Ktz., Chae-
topteris, Ktz., Cladostephus, Ag.) are all small marine Algae, mostly para-
sitic ; ChiKtopteris plumosa (Ktz.) grows on rocks at a considerable
depth below the surface. The thallus usually consists of a number of
TOWS of cells united into a pseudo-parenchyme, and often differentiated
into an appearance of a ' medullary ' row surrounded by ' cortical ' tissue.
In Cladostephus and Stypocaulon these corticating rows of cells descend
to the base of the stem, and form rhizoids or organs of attachment. The
zoosporanges are of both kinds, and are usually placed at the ends of
special branches, while in Stypocaulon they are axillary ; but very little
is certainly known about the germination or possible conjugation of the
swarm-spores. The apical cell of each branch is uncorticated, and fre-
quently develops into a hollow chamber of considerable size termed a
sphacele, filled, when young, with dark mucilaginous contents, which at
.a later stage become watery. Geyler has described two kinds of sexual

250

ALGJE

organ, antherids and ' sexual
spores' (oospheres), formed
within the sphaceles ; but
Janczewski believes that the
supposed antherozoids are in
reality the zoospores of para-
sitic Fungi (Chytridiaceae),
to whose attacks these sea-
weeds are especially liable.
Pringsheim describes two
kinds of fructification pro-
duced by Cladostephus, one
in the autumn, the other in
the winter ; but Wollny sug-
gests that both the autumnal
fructification and the so-
called unilocular sporanges
may be due to the attacks
of parasitic Chytridiaceae.
The Sphacelariaceae have a
strong tendency to multiply
by means of buds, gemmae,
or propagules. Janczewski
describes the mature gemmae
as consisting of a pedicel and

FIG. 223. — Sphacelaria cirrhosa Ag. a, natural size ;
b, branch with propagules, a (x 100) ; c, filament with
unilocular zoosporange ( x 100). (After Hauck.)

FIG. 224. — S. cirrhosa. «, filament
with propagule, b ( x 140). (After
Reinke.)

2 5 1

three rays diverging above, with a hair springing from the centre of the
rays. They become detached like the basidiospores of Fungi, and are
constantly being formed afresh.

LITERATURE.

Geyler — Pringsheim's Jahrb. wiss. Bot., 1866, p. 479.

Janczewski — Mem. Soc. Sc. Nat. Cherbourg, xvi., 1872, p. 337; and Ann. Sc. Nat.,

1873, p. 253.

Magnus — Zur Morphologic der Sphacelarieen, 1873.
Pringsheim — Abhandl. Berlin Akad. , 1873, p. 137.
Rischawi— Algol. Untersuch., i., 1874 (Just's Jahrb., 1874, p. 13).
Wollny — Hedwigia, 1880, p. 65.

The RALFSIACE^E (Ralfsia, Berk., Lithoderma, Aresch., &c.) are small
seaweeds (with the exception of two species of Lithoderma which grow
in fresh running water) with crustaceous thallus, attached to stones,
rocks, or the shells of molluscs and Crustacea, composed of a pseudo-

FiG4 225. — Lithoderma fatiscens Aresch. «, vertical section of portion of thallus with
unilocular zoosporanges ; b, with multilocular zoosporanges (x 320). (After Hauck.)

parenchymatous tissue of vertical rows of cells. They have both kinds
of sporange, collected into wart-like groups or sori on the surface of the
thallus, but nothing is known with regard to the function of the swarm-
spores.

The small order of CUTLERIACE^E, comprising the genera Cutleria
(Grev.), Zanardinia (Nard.), and Aglaozonia (Zan.), consists of a small
number of seaweeds, nearly all natives of warmer seas, although others
from colder climates have been erroneously included in it. The thallus
is coriaceous or membranaceous, flat, and either erect (Cutleria), or
prostrate (Zanardinia), with the peculiarity that the marginal filaments
are dissociated in their growth from the rest of the ' frond.' A true
sexual mode of reproduction has been observed by Reinke in Zanardinia,
and by Falkenberg and Janczewski in Cutleria. The former genus is
monoecious, the latter dioecious. The oogones and antherids are both
collected into sori, the former very dark brown, the latter orange-coloured.

22

ALGA.

,

The oogones are divided into thirty-two or sixty-four cells, each of which
produces an oosphere. The oospheres are at first biciliated swarm-cells
or zoospheres endowed with active motion, closely resembling .the zoo-
spores of other Phasosporeae, but are -larger and variable in form — one of
the very few instances known in the vegetable kingdom of the occurrence

of such, organs. They are
said to be destitute of a
nucleus. The antherids are
also divided into a number
of cells, each of which pro-
duces two antherozoids, the
normal number in an an-
therid (in Cutleria adspersa,
De Not.) being 128. The
antherozoids are also bi-
ciliated swarm-cells, but
smaller than ttye oospheres ;
they have each an orange
pigment-spot, and are iden-
tical in structure with those
of the Fucaceae. The an-
therozoids do not approach
the oospheres until the latter
have come to rest and lost
their cilia ; the absorption
of a single antherozoid into
the oosphere is then suffi-
cient to impregnate it ; it
becomes invested with a
cell-wall of cellulose, and
begins to germinate at
once. Thuret states that
in C. multifida (Grev.) the
oospheres germinate with-
out having been fertilised.
The thallus resulting from
the germination of the im-
pregnated oospheres is said to be dorsiventral, producing rhizoids on
the ventral side only. Zanardinia produces also non-sexual zoospores
iri unilocular sporanges ; and has another non-sexual mode of pro-
pagation, by budding. In Aglaozonia .reptans (Ktz.) the non-sexual
zoospores are the only reproductive organ known ; and Falkenberg

FIG. 226. — Cutleria itniltifida. Grev. (natural size).
(After Hauck.)

FIG. 227.— C. multijida; transverse section of portion of thallus with a sorus of multiloculai
zoosporanges in different stages of development (x 330). ('Alter Bornet.)

FIG. 229.— Fertilisation of Z. cpllaris. a, swarm-
ing oosphere ; b, antherozoids ; c, coalescence
of antherozoid with passive oosphere ; d, oo-
sperm (magnified). (After Reinke.)

FIG. 228. — Zaitardinia. collciris Crouan.
«, oogones ; b, antherids (magnified).
(Arter Reinke.)

.

254 ALG&

regards this species as probably a non-sexual generation in the cycle of
development of Cutleria multifida. The chief argument for placing the
Cutleriacese among the Phseosporeae is the occurrence of non-sexual
zoospores, but the mode of sexual reproduction indicates a distinct
approach to the Fucaceae ; in this latter class, however, the structure of
the antherids is quite different.

LITERATURE.
Janczewski — Mem. Soc. Sc. Nat. Cherbourg, 1872, p. 345, and Ann. Sc. Nat.,xvi.,

1883, p. 210.
Reinke — Monber. Berlin. Akad. Wiss., 1876, p. 565 ; and Nova Acta Acad. Leop. -

Carol, 1878, p. 67.
Falkenberg — Mittheil. Zool. Stat. Neapel, i., 1879, p. 420.

The order DICTYOTACE^E, comprising, according to Bornet, the eight
genera Dictyota (Lmx.), Zonaria (Harv.), Stcechospermum (Ktz.), Lobo-
spira (Thur.), Spatoglossum (Ktz.), Padina (Adans.), Taonia (Ag.), and
Dictyopteris (Lmx.), has been united by some writers with the Cutleriaceae,
while by others it has, with much more reason, been erected into a
distinct class, of equal rank with the Phaeosporese. It differs, in fact,
from the other orders of Phseosporeae in several important points. The
thallus of the Dictyotacese is membranaceous, usually erect flat and
leaf-like, seldom ribbed, often beautifully variegated in zones from the
presence of prismatic hairs or from incrustation of calcium carbonate.
Growth takes place either by means of a single apical cell (Dictyota), or
from a group of equivalent cells. Non-sexual organs of propagation are
known, and other organs which are probably sexual. The Dictyotacese
differ, in the first place, from all other Phssosporeae in the absence of
motile ciliated zoospores. The non-sexual tetraspores are produced in
tetrasporanges developed on the margin of the thallus, or in sori on its
surface, on special non-sexual individuals. Although the contents of
each sporange usually break up into four spores, when they resemble in
all respects the tetraspores of the Florideae, this is not always the case ;
occasionally they divide into only two spores, and still less often the
entire contents of the sporange escape as a single naked spore. The
spores germinate directly, after investing themselves with a cellulose
membrane. The presumed sexual organs, oogones and antherids, are
collected into sori in similar situations, but not on the same individuals
as the tetrasporanges. Some species are monoecious, others dioecious.
The contents of each oogone consist of a single undivided motionless
oosphere. The contents of the antherids, on the other hand, divide into
a large number of motionless pollinoids. Up to the present time, however,
actual impregnation of the oospheres by the pollinoids has not been

PH&OSPORE&

255

observed. As the Cutleriaceae present an approach towards the Fucaceae,
so the Dictyotacese may possibly indicate the point of departure of the

FIG. 230. — Padina Pavonia Gaill. a, natural size ; b, portion of surface of thallus with tetrasporanges ;
c, transverse section of upper portion of thallus; d, of lower portion (x 100). (After Kiitzing.)

Florideae, agreeing with that order in the presence of tetraspores and of
non-motile pollinoids ; but as the oogone presents no indication of even a
rudimentary trichogyne, and there is no process analogous to the forma-

FIG. 231.— Stages in the formation of the tetraspores in Padina. Pavonia (magnified). (After Reinke.)

tion of a cystocarp, it seems best, until more is known of the process of
fertilisation, to retain the Dictyotacese as an aberrant order of Phseosporese,
with which they also agree best in the nature of their pigment.

256 ALG.-E

LITERATURE.

Reinke — Nova Acta Acad. Leop. -Carol. , 1878.
Thuret & Bornet — Etudes Phycologiques, 1878.
Hauck— (Padina) Hedwigia, 1887, p. 41.

The position of the small family of SYNGENETICLE, as constituted by
Rostannski, is one of great uncertainty. The two genera of which it is
composed have generally been regarded as of a very low type of structure,

and it is very doubtful whether they are
nearly related to one another. The pro-
bability seems to be in favour of both
genera having been derived from the
Phaeosporeae by retrogressive metamor-
phosis in different directions. Heckel
and Chareyre (Journal de Microgra-
phie, 1885) regard Hydrurus and Chro-
mophyton as presenting a connecting
link between the Diatomaceae and the
P'haeosporeae.

Hydrurus Ag. consists of a fila-
mentous thallus, attaining sometimes a
foot in length, slimy and affixed to a
conical disc, and growing in cold fresh
running water. The filaments are simple
below but branched above, often with
exceedingly fine penicillate divisions,
filled with a brown or olive endochrome
identical with phycophaein. The sur-
face is naked or densely covered with
delicate hair-like appendages, which are
occasionally fasciculate. The thallus is
composed of cells dispersed through
the gelatinous matrix ; towards the apex
of the branches the cells are in close
contact with one another, but in the
older parts of the thallus they are some
distance apart. Each is surrounded by
a very delicate membrane, and Lager-
heim states that some of them contain
pulsating vacuoles. Propagation takes place by means of zoospores of
very peculiar form, produced in the branches only, two or four from each
cell. When mature the zoospores are tetrahedral, each angle being

FIG. 232. — A, Hydmrus penicillatus Ag.
(natural size). (After Cooke.) B, zoo-
spore (greatly magnified). (After Lager-
heim.)

PHJEOSPORE& 257

prolonged into a slender colourless beak ; in one of the angles is a
brown chromatophore ; and attached to the centre of the opposite side
a single short cilium, and near it two pulsating vacuoles, but no pig-
ment-spot. The zoospores appear to germinate directly without con-
jugation. Lagerheim has also detected, on different individuals from
the zoospores, peculiar resting-spores, through the vitality of which
Hydrurus remains dormant through the summer and autumn, its active
life extending only through the cold season. Hydrurus is placed by
Rabenhorst and Cooke among the Palmellaceae.

Chromophyton Wor. is an epiphytic organism which vegetates and
hibernates within the hyaline cells of the leaves of Sphagnum and other
aquatic mosses. In this state it consists of unciliated naked masses of
protoplasm with pulsating vacuoles, and endowed with an amoeboid
motion. While still within the cells of the host, these bodies become
invested with a delicate cell-wall, multiply by repeated bipartition, and
assume the condition of resting-spores, the endochrome being now of a
brownish red colour. From these resting-spores are developed zoospores,
minute ellipsoidal or nearly spherical bodies, 8-9 //,. long and 4-6 />u
broad, with a single cilium, a contractile vacuole, and a bright yellow
or yellowish brown pigment-disc, consisting of a substance apparently
identical with the diatomin of the Diatomaceae. These zoospores are
imbedded in a colourless mucilaginous matrix, in which condition they
float in large numbers on the surface of the water of bogs in the form of
a fine yellow dust. When completely immersed in water, the zoospores
are set free from their investing mucilage, and at once begin to swarm.
After a time each zoospore develops a second colourless gelatinous
envelope, with a tubular opening below, through which it absorbs water.
In this encysted condition, having now lost its cilium, it multiplies by
bipartition. Although two forms of zoospore have been observed, one
much smaller than the other, no process of conjugation has been detected.
Cornu describes a second species of Chromophyton with stalked bodies
which may be sporanges, and a siliceous coat like that of diatoms.
Although in some respects presenting a resemblance to a degraded
form of Phaeosporeae, it is possible that Chromophyton may be a stage
in the development of some organism belonging to a totally different
class. In some respects it may be compared to the Chytridiaceae
among Fungi.

LITERATURE.

Woronin— (Chromophyton) Bot. Zeit, 1880, pp. 625, 641.

Rostafinski -Hydrurus u. seine Verwandtschaft, Krakow, 1882 (Ann. Sc. Nat., xiv. ,
1882, p. 5).

S

258 ALG^E

Cornu— (Chromophyton) Bull. Soc. Bot. France, 1883, p. xciii.
Hansgirg — Oesterr. Bot. Zeitschr. , 1884, p. 31.
Lagerheim — Ber. Deutsch. Bot. Gesell. , 1888, p. 73.

Phceothamnion Lagerh. (Bot. Zeit., 1885, p. 604) is a fresh-water
alga forming brownish yellow tufts on Vaucheria, Cladophora, &c.
Certain cells develop into zoosporanges, each of which produces two
biciliated zoospores, and the alga has also a palmella condition. Not-
withstanding the brown endochrome, and the fact that the zoospores
germinate directly and have not been observed to conjugate, Lagerheim
places this genus near to Chroolepideae and Chsetophoraceae, making it
the type of a new family; PH^EOTHAMNIE^:. It may possibly, however,
be more nearly related to the Syngeneticae.

Class XIV.- Conjugate.

The Conjugate, as defined by de Bary, constitute an extremely well-
marked and natural group, composed of the three families Mesocarpacea,
Zygnemacea, and Desmidiacetz, with no near affinities (except possibly
with the Diatomaceae). The. individual is unicellular in most of the
Desmidiaceae ; but in some genera of desmids, and in all belonging to
the other two orders, it consists of a filament of cells, which is almost
invariably unbranched. The arrangement of the bright green endo-
chrome, in spiral bands, plates, discs, or stars of beautiful symmetry, is
altogether peculiar to this group of plants, and renders them among the
most interesting and beautiful of microscopic objects. No formation
of zoospores occurs throughout the class, and the ordinary mode of
vegetative increase is by simple cell-division, and the breaking up of old
individuals in the filiform genera into fragments. They retain their
power of life through the winter, when under conditions unfavourable to
the formation of zygosperms, by the production of resting-spores, or
single cells which retain for a long period their vitality. These may be
either akinetes or aplanospores in Wille's sense of the terms. Gay states
(Bull. Soc. Bot. France, 1886, p. 41) that the filaments of Zygnema
(Ktz.), especially when growing in dry situations, have a tendency to
break up into cysts, i.e. fragments which become enclosed in a mucila-
ginous sheath, resulting from the gelifi cation of the outer layers of the
cell-wall. These cysts may preserve their vitality for months, and
then, when moisture again penetrates the sheath, they divide by trans-
verse septa, and develop into new individuals. The single cell of the
Desmidiaceae and the filament of the filiform genera is enveloped in a

CONJUGATE 259

thin transparent mucilaginous sheath. According to Klebs (Untersuch.
Bot. Inst. Tubingen, 1886, p. 333) this sheath is composed of two dis-
tinct portions, a homogeneous substance which is but slightly refringent,
and a portion which consists of minute rods placed at right angles to
the cell-wall. He regards this mucilaginous sheath as entirely independ-
ent of the substance of the cell-wall, and derived from the protoplasmic
contents of the cell by diffusion through the cell-wall. The same struc-
ture probably prevails also in the Confervaceae and other filiform algae
growing in fresh water. The Desmidiaceae possess a remarkable power
of apparently spontaneous motion, which will be spoken of in detail
under that order.

The only sexual mode of reproduction in the Conjugatae is the
conjugation of stationary cells, found nowhere else except in some of the
Zygomycetes. This consists, in the unicellular genera, of the complete
union or fusion of the protoplasmic contents of two individuals ; in the
multicellular genera, of the isogamous union of the whole or a part of
the contents of gametes or non-motile unciliated cells into a zygosperm ;
•conjugation may take place between cells belonging to the same or to
-different filaments. Whether the two conjugating cells are physiologi-
cally equivalent or not will be discussed under the separate orders, and
the process described more in detail. Klebahn finds the union of the
two nuclei in the zygosperm to take place only slowly in Zygnema (Ktz.)
(Zygnemaceae) ; while in Closterium (Nitzsch) (Desmidiaceae) they
remain distinct even in the mature zygosperm.

The Zygnemaceae must be regarded as the typical family of Conju-
gatae, from which the Desmidiaceae have probably been derived by
retrogression, exhibited, in most cases, by the reduction of the filament
to a single cell. The Mesocarpaceae display an approach to a higher
type of sexual reproduction in the more complicated processes connected
with the formation of the zygosperm. The reasons for excluding the
Diatomaceae from- the Conjugatae, contrary to the opinion of some
writers, and placing them in a totally different group, will be given
hereafter.

Many of the Conjugatae are extremely abundant in fresh water,
whether running or stagnant, to which they are almost entirety confined ;
some of the filiform species grow also on moist ground and among
moss.

LITERATURE.

De Bary — Untersuchungen liber die Conjugaten, 1858.

Gay — Essai d'un Monographe des Conjuguees, 1884.

Bennett — Journ. Linn. Soc., xx., 1884, p. 430.

Klebahn— (Zygosperm) Ber. Deutsch. Bot. Gesell., 1888, p. 160.

260

ORDER i.— MESOCARPACE^E.

The species belonging to this family consist of cylindrical unbranched
or very rarely branched filaments of elongated cells, in which the chloro-
phyll is not arranged, as in the Zygnemaceae, in stars or spiral bands,
but in a thin axile plate occupying one diameter in each cell, and con-
taining a number of conspicuous starch-grains ; those of adjacent cells
lying usually or invariably in the same plane. Vegetative propagation
takes place by the breaking up of a filament into its constituent cells ;
sexual reproduction by a process of conjugation, which may take place
either between cells of the same or of different filaments.

The ordinary mode of conjugation in the Mesocarpaceae is that
termed scalariform, viz. between the several cells of two different fila-
ments. In most species of Mesocarpus (Hass.) this takes place in the
following way. When two filaments lie very near one another side by
side,- each cell of each filament puts out a short protuberance on the
side facing the other filament.- While these are forming, the greater
part, but not the whole, of the endochrome in each cell passes into the
protuberance thus formed, a portion being apparently always left behind
As soon as the two protuberances meet, the cell-wall becomes absorbed
at the extremity of each, and an open tube is thus formed in which the
protoplasm of the two conjugating cells coalesces, with expulsion of cell-
sap and consequent contraction into a globular zygosperm. The zygo-
sperm is not formed in the centre of the short tube, but at one extremity
of it, in contact with what may possibly be regarded as the female fila-
ment, although the differentiation is doubtful, and in any case exceed-
ingly slight. The zygosperm may be the result of the coalescence of
three cells instead of two. The zygosperm is at once separated from
the rest of the conjugating tubes, or from the mother-cells, by a septum on
either side. In Staurospermum (Ktz.), where the cells are very long and
narrow, four cells take part in the formation of each zygosperm. Two of
the slender filaments, lying side by side, bend towards one another con-
vexly so as to bring a part of each filament where there is a septum in
contact. Both the septa and the longitudinal bounding-walls become
absorbed at this spot, and the greater part of the contents of the four
cells coalesce into a zygosperm, which is often of a more or less quadrate
form, and is again sharply marked off from the four mother-cells by septa
at the truncated corners. Lateral conjugation also takes place in some
species of Mesocarpus between two adjacent cells in the same filament.
In this process each of the two cells puts out a horn-like protuberance at
the end adjacent to the other cell ; these protuberances bend towards one

CONJUGATE c6i

another and meet ; the septum between them disappears ; the endo-
chromes of the two cells draw towards one another and coalesce, with
condensation of the protoplasm, in the connecting tube thus formed (fig.
235). In M. neaumensis (Bennett, Journ. Micr. Soc., 1886, p. 15) the

FIG. z^.—Mesocarpus panmlus Hass. ;
stages in the formation of zygosperm
( * 750). (After de Bary.)

FIG. 234. — Staurospennum gracillimuin
Hass., with quadrate zygosperms, showing
axile plate of chlorophyll in the cells which
have not conjugated (x 400). (From)
nature.)

zygosperm is not formed in the connecting tube, but in one of the con-
jugating cells. In Gonatonema (Wittr.) parthenosperms are said to
be formed closely resembling zygosperms, but not resulting from the

coalescence of the contents'of two cells. Several species of Mesocarpus
frequently put out long connecting tubes between two filaments, which
assume a barrel-shaped form, but without any formation of zygosperms.
In this condition they closely resemble Mougeotia (de By.).

The most important point in which the Mesocarpaceae differ from
the Zygnemaceae is in the processes which take place after the formation
of the true zygosperm. Immediately after its formation, it divides into
two, three, or more cells, the central one only of which is fertile, ger-
minating after a period of rest ; the other sterile cells, which are separated
from the fertile cell by septa, taking no part in the germination. The
germinating cell is therefore here a resting-spore or hypnospore, produced
non-sexually, and the whole structure is, as Pringsheim points out, a
rudimentary sporocarp, indicating an approach to the higher classes of
Algae ; while the family is, on the other hand, con-
nected with the Zygnemaceae through the species of
Zygnema in which the zygosperm is formed in the
connecting tube; and the best writers are by no means
agreed as to the limits of the two orders.

Wittrock has described the formation of the ' spo-
rocarp ' as taking place in three different ways in the
Mesocarpaceae, viz.: — (i) By the tripartition of the
zygosperm into a hypnospore and two sterile cells;
when the conjugation is lateral, the sterile cells are
not separated from one another by the hypnospore,
FIG. 235.— Mesocarpus but are permanently united with one another. (2)

pleurocarpus de by. ; _. , . . . ", , 1-11

lateral conjugation -By quadnpartition of the zygosperm ; this has been
tie!?* (Fr°m na~ observed only in the case of scalariform conjugation,
the sterile cells being arranged two on one side and
one on the other side of the hypnospore. (3) The zygosperm is cruci-
form or H -shaped, and the sporocarp is formed from it by quinqueparti-
tion, two sterile cells bounding the hypnospore on each side ; this
mode also only takes place in scalariform conjugation. Although these
characters have been used by Braun and others for the separation of
the genera of Mesocarpaceae, Wittrock regards them as of very little
systematic value, since in one species, Mougeotia calcarea (Wittr.), he
observed all three modes of reproduction on one and the same fila-
ment. In this same species Wittrock also records the formation of
parthcno sperms, precisely resembling the normal zygosperm?, but not
resulting from any act of conjugation. An outgrowth springs from
a filament, but is not met by any corresponding outgrowth from an-
other filament. It is, however, cut off by a septum, and divides into
sterile cells and a hypnospore, just as if fecundation had taken place.

CONJUGA T.-E 263

In Gonatonema notabile (Wittr.) parthenogenetic hypnospores are formed
by tripartition of the contents of an ordinary cell which swells up into
the form of a cask.

The phenomenon of reproduction in the Mesocarpaceae is regarded
by some as a rudimentary appearance of an 'alternation of generations.'
The sexual generation or oophyte is completed by the production of the
zygosperm as the immediate product of fecundation. This does not
germinate directly, but its- formation is immediately followed by cell-
division, or the development of the non-sexual generation or sporophyte ;
the sporocarp consists of the germinating hypnospore — in the immediate
formation of which no process of impregnation took part — and the in-
vesting sterile cells or ' pericarp.' Pringsheim, regarding the process of
conjugation in the Mesocarpaceas as representing a distinctly higher type
than that in the Zygnemaceae, divides the process in the former family
into two stages. The first stage, to which he applies the term ' copula-
tion,' consists in the simple union of two cells by the absorption of the
dividing cell-wall ; the second stage is an intimate coalescence of the
protoplasmic contents of the conjugating cells, effected by the motility of
the chlorophyll-bodies; and this stage he terms 'connubium.' The
hypnospore might, indeed, be correctly termed a ' carpospore,' and we
have here a point of departure in the direction of a much more highly
specialised type of structure. But the complete similarity of the two
conjugating cells before conjugation necessitates the retention of the
Mesocarpaceae among the Conjugatae.

Limiting the order in accordance with the above-named characters,
the genera which the Mesocarpaceae comprise are Mesocarpus (Hass.),
Staurospermum (Ktz.), Craterospermum (Br.), and Gonatonema (Wittr.).
Several species of Mesocarpus and Staurospermum are not infrequent in
stagnant water, especially in moor pools and among Sphagnum. The
filaments are not so copiously invested with mucilage and not of so
bright green a hue as those of the Zygnemaceae ; Staurospermum
capucinum (Ktz.) has a beautiful violet tinge.

LITERATURE.

Wittrock — Algologiska Studier, Upsala, 1867 ; Orn Gotlands och Oelands Sotwas-
seralger, 1872 (Quart. Journ. Micr. Sc., 1873, p. 123); On the Spore-formatioa
of the Mesocarpece, 1878.

264

ALG^F.

ORDER 2. — ZYGNEMACE^E.

The individual consists, as in the Mesocarpaceae, of a filament of
cells placed end to end, which is almost always simple and unbranched.
The filaments are cylindrical, and the cells of which it is composed often
of comparatively large size ; those of Spirogyra crassa (Ktz.) as much as
.g.^ of an inch (125 //.) in diameter, and twice as long as broad. The
chlorophyll is arranged in one or more straight (Siro-
gonium, Ktz.) or more commonly spiral (Spirogyra, Lk.)
bands, or in stars placed in pairs in each cell (Zygnema,
Ktz.), or occasionally in an axile plate (Mougeotia,
deBy.), and encloses large starch-grains and a nucleus,
often very large and easily discernible even without the
use of staining reagents, connected with the parietal
protoplasm by radiating threads. In some species ot
Zygnema the characteristic appearance of the endo-
chrome is assumed only when the cells are about to
conjugate. The ease with which some members
of this family, especially species of Spirogyra and
Zygnema, are .. cultivated in fresh-water aquaria, and
the beautiful arrangement of the endochrome, not only
make these algae extremely striking objects under the
microscope, but afford especially good opportunities for
observing, in their details, the processes of division
of the nucleus and of the cell.1 It is also in this
family that the interesting process of conjugation is
most easily followed.

The filaments increase in length by ordinary cell-
division ; and single cells, which become very easily
detached, are able to develop in this way into new
individuals, corresponding, therefore, functionally to
the non-sexual spores of fungi. Like the Desmidiaceae
and other floating algae, they can obtain their nourish-
ment entirely from the water, and increase without
any attachment to the substratum. The formation of
resting-cells and of cysts has already been mentioned. The only other
known mode of reproduction is by conjugation ; but the reproductive
organs of other algae or fungi, which are sometimes parasitic upon or

FIG. 236. — Spirogyra
por tic alls Vauch. ;
stages in the forma-
tion of zygosperm
( x 100). (From
nature.)

1 See Strasburger, Ueber Zellbildung und Zelltheilun^
Botany ', 2nd English cd. 1882, p. 16.

also Sachs, Text-book cf

CONJUGA T^E

265

'endophytic in species of Spirogyra and Zygnema, have been mistaken
for zoospores.

The usual mode of conjugation is the scalariform, between the cells
of two filaments lying side by side. The first stage is the putting out of
lateral protuberances at right angles to the axis of growth, from the cells
in each filament towards the corresponding cells in the other filament.
The protuberances put out by opposite cells at length meet ; the proto-
plasm-mass of each of the two cells has by this time begun to contract,
withdrawing itself from the cell-wall, and rounding itself off into an ellip-
soidal form, with expulsion of some
of its cell-sap, the chlorophyll-
bodies at the same time losing
their characteristic arrangement.
The cell-wall then opens between
the two protuberances, and the
whole of the protoplasmic con-
tents of one of the two cells
passes through the connecting
tube thus formed, and glides
slowly through it into the other
cell-cavity, coalescing with its pro-
toplasm-mass. After complete
union the combined protoplast is
again ellipsoidal or spherical, and
scarcely larger than each of the
two before coalescence, further
expulsion of water and conse-
quent contraction having taken
place. In some species of Zyg-
nema the zygosperm is formed,
not in either of the conjugating
cells, but in the connecting tube,
as in the Mesocarpaceae. In Sirogonium no connecting tube is formed,
but conjugation takes place by genuflexion ; the two filaments are brought
into contact by a knee-like bend in each ; at the point of contact the
adjacent cells of the two filaments are placed in communication by the
disappearance of the cell-walls, and a zygosperm is formed in one of the
two cells by the coalescence of the two protoplasts.

A second mode of conjugation, not nearly so frequent, is the lateral,
between two contiguous cells of the same filament. Protuberances
formed near the adjacent ends of contiguous cells bend towards one
another till they meet ; the cell- wall between them then disappears,:

FIG. 237. — Zygnema pecti-
natnm Ag., in conjugation
(x 100). (After Cooke.)

FIG. 238. — Spiro-
gyra be His Hass. ;
lateral conjuga-
tion ( x 100).
(From nature.)

266

and conjugation is effected though the curved tube thus formed by the
coalescence of the protoplasts of the two cells. The zygosperm is never
formed, as irt the Mesocarpaceae, in the connecting tube, but in one of
the two cells. Lateral conjugation frequently takes place with groups
of four cells, the zygosperms being formed in the two central ones.

The protoplast formed by either mode of conjugation finally secretes
a cell-wall of cellulose, and becomes a zygosperm. Germination some-
times takes place while still within the mother-cell ; but most commonly
both filaments perish after conjugation, with the exception of the
numerous zygosperms, which fall to the bottom, the green endochrome
having in the meantime turned to a brick-red colour. It then remains
dormant through the winter as a resting-cell or hypnospe rm, germinating
in the spring. Whether the axis of growth of the new individual is
parallel or at right angles to that of the old individual is differently
stated by different observers. On the commencement of germination,
one end of the zygosperm of Spirogyra attaches itself like a root to a
stone or to some other alga, so that in the earliest stage of the new
individual there is a differentiation between base and apex ; but this
soon disappears. The innermost of the three layers of which the cell-
wall of the hypnosperm is composed bursts through the other two, and
protrudes like a bag. The chlorophyll then arranges itself in spiral
bands, with starch-grains within them, and the cell divides by transverse
septa into a filament, all the cells being from this time precisely alike.
Instances are recorded of filaments persisting through the winter.
Hofmeister states that the growth of Spirogyra is intermittent, and that
the filaments exhibit a nutation, due probably to differences in the
rapidity of growth of different sides of the same cell. Where branching
takes place, it appears to be confined to the barren portion of a filament
in which zygosperms have been formed.

Although the view is contested by some writers, the process of
conjugation is regarded by most as a sexual process, but one of the
most rudimentary character, the differentiation of the two conjugating
elements being exceedingly slight. As de Bary has pointed out — and
his statement is confirmed by nearly all more recent observers — the
direction of conjugation is clearly governed by some physiological law,
the movement of the protoplasm between the two filaments almost
invariably taking place in one direction only, so that one of the two
conjugating filaments is entirely emptied, while the other is filled with
zygosperms.1 Designating the former as the male and the latter as
the female filament, it is frequently the case that the cells of the

1 Hassall, however, asserts and figures the contrary (British Fresh -water Algcs,
i,, p. 130).

CONJUGATE 267

female are both longer and broader than those of the male filament ;.
and the contraction of the protoplasm has been observed to begin
earlier in the male than in the female filament. It is also stated that
the protuberance from the female cell is shorter but broader than that
of the male cell, the latter fitting into the former as into a socket. The
chief argument against the sexuality of the filaments is the occurrence
of lateral conjugation ; and when this takes place a sexual differentiation
can be assumed only of the individual cells and not of the filaments ;
but that there is some differentiation of this kind would appear from the
fact that when lateral conjugation takes place in a group of four cells
the zygosperms are formed in the two centre cells, which may be
regarded as female. The phenomena may then be compared to those
in Sphaeroplea. Bessey states (in lit.) that scalariform and lateral conju-
gation may sometimes be seen in different parts of the same filament.
The female filaments are, as a rule, very much more abundant than the
male ; and it is not uncommon for conjugation to take place between
one male and several female filaments, while the reverse is at all events
much more rare. Occasionally one cell will conjugate with two others,,
the zygosperm being then the product of one female and two male cells.
Several instances are recorded of hybridism between two different species
of Spirogyra. Parthenogenesis, or the formation of parthenospe nhs
capable of germination, and in all respects resembling zygosperms, but
formed out of the contents of a single cell without any previous process
of conjugation, is also stated to occur.

The genera included in the Zygnemaceae with the above characters
are Zygnema (Ktz.), Spirogyra (Lk.), Mougeotia (de By.), Sirogonium
(Ktz.), and Zygogonium (Ktz.). Several species of Spirogyra and
Zygnema are among the commonest of fresh-water Algae in both stagnant
and running water, forming dense bright green masses, often with a
slimy feel, owing to the well- developed mucilaginous sheath in which
each filament is enveloped. While conjugation is in active progress,
which is mostly in the early summer, the filaments of Spirogyra assume
a dull green or even brown colour, easily recognised by the naked eye..
The other genera are more frequent in moor pools.

LITERATURE.

Pringsheim — Flora, 1852, pp. 465 et seq.

Cleve — Monografi Zygnemaceae, 1868.

Hofmeister — Wiirtemb. naturw. Jahresheft, 1874, p. 211.

Overton— Ber. Deutsch. Bot. Gesell., 1888, p. '68.

(For fuller bibliography see Bennett, Journ. Linn. Soc. , xx. , 1884, p. 430).

268 ALGsE

ORDER 3. — DESMIDIACE^:.

The Desmids are unicellular organisms, for the most part solitary,
and inhabiting almost exclusively fresh water, especially stagnant, where
they occur in very large numbers; a very few species are brackish.
They always float free without any attachment to the bottom or to other
algae," and many species possess a power of apparently spontaneous
motion through the water similar to that of diatoms, though not so
strongly marked. In several genera, as Desmidium (Ag.) and Hyalotheca
(Ehrb.), the individuals are united into long filaments ; and either the
separate individuals or the filaments are invested by a more or less
dense mucilaginous envelope, species of Desmidium and Hyalotheca
frequently forming a green slime on the surface of moor pools. The
origin and structure of the mucilaginous sheath appear to be the same
as in the Zygnemacese. According to Hauptfleisch, the cell-wall of
desmids always consists of two distinct layers, sometimes of more, which
are then provided with a girdle-band similar to that of diatoms. He
also states that in nearly all species the cell-membrane is perforated,
and that through these pores proceed threads of protoplasm, connecting
the protoplasm in the interior of the cell with the gelatinous envelope
which is excreted through the pores from the cell-contents. In the
filamentous species the protoplasm is probably in connection throughout
the filament.

The cells vary greatly in size and form in different species, the
largest (Cosmarium, Cord., Micrasterias, Ag.) being just visible to the
naked eye. The individual is usually divided by a deep constriction into
two symmetrical halves ; and even where this is not the case, the cell-
contents— chlorophyll-bodies and starch-grains — are symmetrically
arranged in the two halves of the cell. The cell-wall is smooth, or
punctated, warty, or even elevated into spines, but has no (or very little)
deposit of silica. The cells contain a large quantity of chlorophyll of a
bright green colour, never concealed by any pigment, often arranged in
bands or stars, and containing much starch. Each genus has its own
general form of cell, often of very great beauty. In Docidium (Breb.),
Penium (Breb.), and Tetmemorus (Ralfs) the individual or ' frustule '
is elongated, cylindrical, and usually divided by a constriction into two
halves placed end to end; in Closterium (Nitzsch) it is crescent- shaped;
in Micrasterias it is very thin and flat, usually with a more or less orbi-
cular or elliptical outline, deeply divided into two symmetrical halves,
and each half more or less deeply lobed ; in Euastrum (Ehrb.) the indi-
vidual is usually smaller than in Micrasterias, often very minute, and

CONJUGATE

269

the half-cells have a smooth, sinuate, or beaked margin, with circular in-
flated protuberances ; in Cosmarium the half-cells are quite undivided,
and the whole outline often nearly orbicular; in Xanthidium (Ehrb.)
and in most species of Staurastrum (Mey.) the surface is elevated into
prominent tubercles or spines.

The transparency of the cell- wall in desmids enables the rotation of
the protoplasm to be distinctly seen ; and at the colourless spaces at
the extremities of some species of Closterium and Docidium the dancing
'brownian' movement of particles suspended in the cell-sap is very

FIG. 239.— A, Desmidium Siuartzii Ralfs ; B, Micrasterias rotata Grev. ; c, Euastrum ro stratum
Ralfs ; D, Cosmarium ccelatum Ralfs; k, Xanthidium cristatum~&r€b. \ F, Staurastrum Arachne
Ralfs ; G. Closterium DiattaEhrb. ; H, Docidium baculum Br£b. (All after Ralfs and variously-
magnified.)

evident. Klebs describes four kinds of movement in desmids, viz. : —
(i) A forward motion on the surface, one end of each cell touching the
bottom, while the other end is more or less elevated and oscillates
backwards and forwards ; (2) an elevation in a vertical direction from
the substratum, the free end making wide circular movements ; (3) a
similar motion, followed by an alternate sinking of the free end and
elevation of the other end ; and (4) an oblique elevation, so that both
ends touch the bottom — lateral movements in this position ; then an
elevation and circular motion of one end, and a sinking again to an
oblique or horizontal position. These movements are, according to this
observer, all due to an exudation of mucilage, and the first two to the.

270

ALG.-E

formation, during the motion, of a filament of mucilage by which the
desmid is temporarily attached to the bottom, and which gradually
lengthens. The movements of desmids are especially vigorous when
they are in the act of dividing. Stahl found that, like the movements
of zoospores, they are affected by light.

Vegetative propagation takes place by division or fission, a process
which can be easily followed out in species of Cosmarium or Staurastrum,
the whole being completed in the course of a few hours. When cell-
•division is about to commence, the endochrome retreats slightly from
the band or ' isthmus ' which connects the two half-cells with one an-
other; and the two halves then separate from one another, retaining
their connection only by a transverse band formed by the gradual
broadening of the isthmus ; this is after a time divided into two by

a septum along the length of
the isthmus, midway between the
two half-cells and parallel to the
constriction between them. The
endochrome now passes out of
each original half-cell into the
half of the band in connection
with it, and at the same time the
half-band bulges, and, growing
rapidly, assumes the form and
appearance of an original half-
cell. Fresh formation of chloro-
phyll is at the same time taking
place in it, and the half-band becomes a complete half-cell, but some-
times slightly larger. We have now two individuals attached to one an-
other by their larger halves ; these frequently remain in contact for a
•considerable period, but at length separate. In the spiny species of
Staurastrum the spines are developed very rapidly on the half-bands
while their development into half-cells is progressing.

A sexual process of conjugation takes place in the following way
in the genera where the individuals are quite distinct. Two individuals —
which cannot in any way be differentiated as male and female — lay them-
selves either parallel to or across one another, and the pair become en-
veloped in a common mucilaginous coating. In each individual the
outer of the two layers of which the cell-wall is composed gives way, and
a circular opening is formed at the constricted part ; the inner layer of
the cell-wall of each individual protrudes through the opening in the
form of a bladder, and these two protrusions come into contact. The
outer cell-wall is then thrown off, and the wall separating the two con-

FIG. 240. — Staurastrum teliferum Ralfs, dividing
(x 400). (From nature.)

CONJUGA T.'E

271

jugating protrusions disappears. The two protoplasmic bodies then
unite in the conjugating tube thus formed into a nearly spherical zygo-
sper?n, enclosed in a cell-wall which ultimately becomes differentiated
into three layers, the innermost and outermost of which are colourless,
while the middle one is firmer and brown. The outer surface remains
in some species smooth, while in many it becomes, when mature,
covered with warts or spines, which are not unfrequently barbed. In
those genera where the individuals are associated into filaments, conju-

FIG. 241.— Zygosperms of desmids. A, Euastrum pectinatrim Br£b. (x 400). B, Penhtm
margaritaceum Brdb. (x 300). c, Closterium rostratuin Ehrb. early stage ( x 200). D,
Desmidiutn. Swartzii Ralfs ( x 600), (All after Ralfs.)

gation takes place between the cells of different filaments, and a
large number of zygosperms may frequently be seen in the same fila-
ment. In Gonatozygon (de By.), where the cells are very long and
slender, the process is very similar to that in Zygnema. The state-
ment of the occurrence of zoospores in the Desmidiacese is founded on
erroneous observation, the antherozoyis of parasitic fungi having pos-
sibly been mistaken for zoospores.

After remaining for a considerable time at rest, the zygosperm ger-
minates by the bursting of its two outer coats, the protoplasmic contents
escaping still enveloped in the very thin innermost coat. In this embryo.

2/2 ALG^E

as it may be termed, the protoplasm and chlorophyll-corpuscles are
already distributed symmetrically into two half-cells, which contract
somewhat, and the whole becomes invested by a new cell-wall. A con-
striction has in the meantime made its appearance between the two
halves, and the new individual rapidly assumes its mature form, but is
at first of small size. It soon divides repeatedly, and each generation
gradually increases in size until the full size is attained.

The number of known species'of desmids is not large compared with
that of diatoms ; they are found in great abundance in the midst of
larger algae in fresh water, especially in moor-pools, sometimes forming
a green scum on the surface.

LITERATURE.

Ehrenberg — Die Infusionsthierchen, 1838.
Ralfs— British Desmidiese, 1848.
Nageli— Gattungen einzelliger Algen. 1849.
Stahl— Verhandl. Phys.-med. Gesell. Wiirzburg, 1880, p. 24.
Fischer — Bot. Zeit., 1883, pp. 225 et seq.
Wolle— Desmids of the United States, 1884.
Klebs— Biolog. Centralblatt, 1885, p. 353.

Cooke — British Desmids, 1887 (which see for farther bibliography).
Hauptfleisch — Zellmembran u. Hiillgallerte der Desmidiaceen, 1888.

Class XV.— Confervoideae Isogamae.

In this class the individual still consists of a filament of cylindrical
cells, placed end to end, which may be branched or unbranched. As
in the Conjugate, the only known sexual mode of reproduction is an
isogamous one between two masses of protoplasm, which are not clearly
differentiated beforehand into a male and a female element ; but the
conjugating bodies are not the contents of stationary cells, but are
motile ciliated swarm-spores or zoogametes, produced by free-cell forma-
tion in ordinary or in slightly differentiated cells of the filament, hence '
termed gametanges, their conjugation resulting in the production of a
zygosperm. The filament increases in length by the repeated transverse
septation of successive apical cells, or less often of intercalary cells.
The ordinary mode of multiplication is a non-sexual one, by means of
~naked ciliated zoospores, closely -resembling the zoogametes, but often
larger, and formed singly or in pairs in a cell. Vegetative propagation
also takes place by the formation and detachment of cysts or resting-
cells, which may be either akinetes or aplanospores. The cells very
frequently display a plurality of nuclei, but this is not nearly so strongly

CONFERVOIDE^: ISOGAM&

273

marked as in the unicellular Multinucleatae. The class includes one
large order, the Confervacece, and three smaller ones, the Ulotrichacta,
Pithophoracece, and Chroolepidece, though the boundaries between them
are not in all cases well denned. In the Confervacese and Ulotrichaceos
the filament which springs from the germination either of a zoospore
or of a zygosperm resulting from the conjugation of zoogametes, attaches
itself to the substratum — a stone, another alga, or some other aquatic
plant — by a rhizoid, which may consist of a single cell, or may branch
into a number of cells. As in the higher algae, the rhizoid is not a
nutritive organ, but simply an organ of attachment. These algae may,
however, continue to grow and retain their vitality for a long period in
water without any attachment to the substratum.

ORDER i. — CONFERVACESE (i

The term Confervacese has been very
vaguely applied to a variety of green fresh-
water organisms, but is now limited to a
comparatively small number of genera of
fresh-water, and a few brackish and salt-
water algae, in which each individual
consists of a segmented branched or un-
branched filament of cylindrical or disc-
shaped cells, invested by a mucilaginous
sheath, and in which multiplication takes
place non-sexually by megazoospores, or
sexually by the conjugation of smaller
zoogametes. Both kinds of swarm-cell have
two cilia, or the former in some cases
four ; Lagerheim describes, in Conferva
bombycina (Ktz.), megazoospores with a
single cilium. From each parent-cell are
produced either one or two megazoospores.

In only a few species has the process
of conjugation of zoogametes been actually
observed, and the systematic position of a
large number of the species is therefore
at present only conjectural. Areschoug has FIG. w.—Microsporajio
followed both the conjugation of the zoo-
gametes and the direct germination of the
megazoospores in Urospora (Aresch.). In
Conferva (L.), Chaetophora (Schr.), Draparnaldia (Ag.), and some other

§ 2t

zoospores (x 30o)'

274

ALGsE

FIG. -z^.—Cladophora. gracilis Ktz. a, natural size
l>, upper, c, lower portion (x 200). (After Hauck.)

genera, vegetative propagation
takes place by means of resting-
spores or cysts, usually found
in swollen barrel-shaped cells.
In Conferva the resting-cells
may be either akinetes or apla-
nospores ; and Wille believes
that they are produced espe-
cially under circumstances un-
favourable for the formation of
zoospores. The resting-spores
of Confervacese are formed in
three different ways: either (i)
by rejuvenescence, and the for-
mation of a new cell-wall round
the contracting contents; or (2)
by separation of a portion of the
cell-substance so as to form a
swollen part of the mother-cell,,
and the thickening of the cell-
wall at this portion; or (3) by
the simple thickening of the
wall of the mother-cell. In the
formation of aplanospores, one,
two, or four proceed from • a
single cell by the cell-contents
rounding off and enclosing
themselves in a cell-wall while
still within the parent-cell. They
hibernate within the parent-cell,
and germinate in the spring.
Resting swarm - cells^ naked
masses of protoplasm endowed
with an amoeboid power of mo-
tion, are formed in the same
way.

The mucilaginous sheath of
the Confervaceae appears to
have the same construction as
in the classes of algae already
described, but is often but feebly
developed. Wille states that the

CONFERVOIDE^E ISOGAMsE

275

spores put out an organ of attachment even before they germinate. In
Chsetophora and other genera which make up the Chaetophoraceae of
Hassall, the terminal cell of the main axis or of its branches is prolonged
into a colourless hyaline bristle. These are especially well developed
in Draparnaldia, an exceedingly beautiful organism not uncommon in

FIG. 244. — Draparnaldia gloinerata Ag. (x 100). (From nature.)

freshwater, which exhibits a somewhat higher type of development than the
other genera, being differentiated into an axis or central tube, and smaller
secondary branches arranged in regular whorls ; the zoospores being
produced in the latter only. Maupas states (Compt. Rend., Ixxxix., 1879,
p. 250) that the cells of Cladophora contain a large number of nuclei ;
and Schmitz (Sitzber. Niederrhein. Gesell., 1879) finds four nuclei in a

276 ALG.-E

cell in certain conditions of Conferva. In this, and in the possession of
proteinaceous crystalloids (Klein, Bot. Zeit, 1880, p. 782), these genera
show an affinity to Siphonocladaceae. Binuclearia ( Wittr. ) (Bot. Centralbl.,
xxix., 1887, p. 60) appears to have always two nuclei in each cell.

There are still many points to be cleared up in the life-history of
the Confervaceae, although some of the genera are among the most
abundant of fresh-water organisms ; and the bounds and systematic
position of the family are still uncertain. According to some observers,
many of the species are connected genetically with forms at present
placed under the Protophyta ; to this view further reference will be
made hereafter. Andersson (Bot. Centralbl., xxxv., 1888, p. 351) believes
Palmella uvaeformis (Ktz.) to be a resting condition of Draparnaldia.
Among the genera now included in the order are Conferva (L.), Micro-
spora (Thur.), Cladophora (Ktz.), Rhizoclonium (Ktz.), Stigeoclonium
(Ktz.), Chaetomorpha (Ktz.), Draparnaldia (Ag.), Chaetophora (Schr.),
Urospora (Aresch.), and Binuclearia (Wittr.). Phseothamnion (Lagerh.)
(see under Syngeneticae) ought possibly to be included here; as also
Spongocladia (Aresch.) (see p, 290). Several species of Cladophora,
Chaetomorpha, and Rhizoclonium grow in brackish or even in salt water.

LITERATURE.

Vaucher — Hist, des Confervas d'eau douce, 1803.

Areschoug - Nova Act. Reg. Soc. Upsala, vi., 1868, and ix., 1874.

Reinhardt— Arb. Naturf. Gesell. Charkoff, 1876.

Wille — Bot. Centralbl. , xi., 1882, p. 113; and Pringsheim's Jahrb. wiss. Bot., 1887,

PP- 437> 459. and 492.

Lagerheim— Ber. Deutsch. Bot. Gesell., 1887, p. 409.
Murray and Boodle — (Spongccladia) Ann. of Bot., ii., 1888, p. 169.

ORDER 2 (?). — PITHOPHORACE^E.

The Pithophoraceae must be admitted as a distinct order only with
very great doubt, both because the mode of sexual reproduction is at
present unknown, and because of their strong resemblance to the Con-
fervaceae. The family, consisting of a single genus, was founded on
Pithophora Kewensis Wittr., an inhabitant of warm tanks in the
Botanic Gardens at Kew, Oxford, and elsewhere ; other species have
since been found in tropical America. The thallus is composed of
branching 'filaments of cells resembling Cladophora, but increasing only
by bipartition of the terminal cell, and presenting here and there barrel-
shaped cells very rich in chlorophyll, in which are formed resting-spores
of non-sexual origin. These germinate directly, and in opposite direc-
tions, from the two apices. There is another mode of non-sexual pro-
pagation by ' prolific cells ' ; but no zoospores nor any sexual mode of

CONFERVOIDEsE ISOGAMAZ

277

reproduction have as yet been detected.
They are distinguished by the remarkable
development of their rhizoids or organs of
attachment.

LITERATURE.

Wittrock— On the Development and Systematic
Arrangement of the Pithophor<xce0e, 1877.

ORDER 3. — ULOTRICHACE^E.

This small order includes the genera
Ulothrix (Ktz.), Hormiscia (Aresch.), and
perhaps one or two others, not uncommon .
in fresh and occasionally in brackish water.
The life-history of U. zonata (Ktz.) and
other species has been investigated by
several observers. They exhibit consider-
able affinity both to the Confervacese and
to the Hydrodictyeas. Each individual
is composed of an unbranched filament of
short cells, broader than long, and nearly
uniform in length. Some of the cells are
megasporanges, giving birth to 2, 4, or 8
megazoospores with 4 cilia; others are
microsporangesmgametanges, producing 16
or 32 biciliated microzoospores or zooga-
metes. From the non-sexual megazoo-
spores to the zoogametes there is, however,
a gradual transition, the only constant dif-
ference between them being the number
of cilia. Those microzoospores which do
not conjugate, as well as the megazoo-
spores, germinate directly, germination
sometimes taking place even within the
mother-cell. Their escape is, however,
sometimes arrested, when they lose their
cilia, invest themselves with a thick cell-
wall, and assume a palmelloid condition.
The plants which spring from the germina-
tion of the megazoospores are larger than
those which spring directly from the micro-

(After wi"rock.)

278

ALGsE

zoospores, as also than those which spring from the zygosperms resulting
from the conjugation of the zoogametes. The escape of the swarm-spores
was observed by Cramer to take place, usually in the morning, even in
water which froze on the surface every night, conjugation following
quickly afterwards. The two kinds of swarm-spore are never produced
in the same cell, but in different cells of the same filament, and Cramer
believes that conjugation takes place between zoogametes from the same
filament. The megazoospores use up in their formation the whole proto-
plasmic contents of the mother-cell, while in the production of the
*

FIG. -2i£>. — Ulothrix implexa Ktz. a, vegetative filament (x 480); b, portion of the
same ( x 800) ; c, palmella-condition ( x 480) ; d, escape and conjugation of zoogametes
( x 800). (After Dodel-Port.)

microzoospores or zoogametes a portion of the contents forms a bladder
which escapes with them, but soon perishes. According to Wille (Bot.
Centralblatt, vol. xi., 1882, p. 113) Ulothrix also produces cysts or rest-
ing-spores, which may be either aplanospores or akinetes. In some
other members of the order the filament is branched. Schaarschmidt
points out that a state closely resembling the microsporiferous filaments
of Ulothrix occurs in the development of the Confervaceae ; and

CONFERVOIDEsE

279

Hansgirg (Bot. Centralblatt, 1885) believes that the filamentous genera
placed in this genus are connected genetically with forms classed under
the Chaetophoraceae, Siphonocladaceae, and Ulvaceae. To this order
belong also Hormidium (Ktz.) and Schizogonium (Ktz.).. Wildeman
(Bull. Soc. Bot. Belg., 1886, p. 7) traces a genetic connection between
Ulothrix and Pleurococcus.

LITERATURE.

Cramer — Vierteljahrschrift Nat. Gesell. Ziirich, 1870.
Cier.kowski— Mel. biol. Bull. Acad. St. Petersbourg, 1876, p. 531.
Dodel-Port— Pringsheim's Jahrb. wiss. Bot., 1876, p. 417; Bot. Zeit., 1876, p. 177.
Gay— Bull. Soc. Bot. France, 1888, p. 65.
Hansgirg— Flora, 1888, p. 259.

ORDER 4. — CHROOLEPIDE^E.

This order, as constituted by Borzi, comprises a small group of
algae found on damp walls, the trunks of trees, and similar situations,
not unfrequently imbedded in the thallus of lichens, or constituting their
gonidial element. The thallus consists of a branched or unbranched
filament of cells, usually
somewhat rounded or mo-
niliform in outline, and is
distinguished by the mask-
ing of the colour of the
chlorophyll by a golden
yellow, orange, or red oily
pigment, soluble in alcohol
and imparting a strong
odour of violets. This pig-
ment, which occasionally
occurs also in other lowly
organised algae and proto-
phytes, has been examined
by Rostafinski, and found
to be a derivative of chlo-
rophyll to which he gives
the name chlororufin.
Microzoospores or zooga-

. __„. _, Bleischii Rbh. A, filament with

ITieteS and megaZOOSpOrCS swollen cells in which the zoogametes are formed (game-

, - .. tanges), g; £, stages in the conjugation of the zoogametes

are produced in gametanges ( x 33o). (After wiiie.)

or zoosporanges, which are

indistinguishable from the vegetative cells except by their somewhat larger

size, and which are either terminal or intercalary. Conjugation of the

280 ALGsE

smaller swarm-spores has been observed in Chroolepus (Ag.), but they can
also germinate without conjugation. Chroolepus also produces resting-
spores. Of this genus one species, C. aureum (Ktz.), is common on walls
and rocks, and another, C. umbrinum (Ktz.), occurs on the bark of trees.
C. lolithus (Ag.) is one of the few algae that grow in perfectly dry situations
on gneiss &c., and on a siliceous rock in the Hartz Mountains known as
' violet-stone.' The genus Trentepohlia (Mart.) is now merged by many
writers in Chroolepus. Wille has pointed out that the organism de-
scribed as Gongrosira de Baryana (Rbh.), which grows attached to the shell
of fresh-water molluscs as a green velvety coating, is a form of Chroolepus
or Trentepohlia.

The genera included under the Chroolepidese by Borzi in addition to
Chroolepus and Trentepohlia are Microthamnion (Nag.), Acroblaste
(Reinsch), Leptosira (Borz.), Chlorotylium (Ktz.), and Pilinia (Ktz.).
Acroblaste grows in salt water attached to mussel-shells, but its position
here is doubtful. Leptosira produces zoospores, some of which germi-
nate directly, while others are said to conjugate, but in a manner different
from other zoogametes, by the end which does not bear the cilia. To
this family probably belongs also Trichophilus (Weber), a remarkable
alga parasitic on the hairs of a sloth, which produces two kinds of
zoospore (Bot. Centralblatt, vol. xxxiv., 1888, p. 161).

LITERATURE.

Caspary — Flora, 1858, p. 579.
Hildebrand— Bot. Zeit., 1861, p. 81.
Gobi— Bull. Acad. Sc. St. Petersbourg, 1872.

Schnetzler— Bull. Soc. Vaud. Sc. Nat., 1879, p. 267 ; 1880, p. 13 ; and 1883, p. 53.
Borzl — Studi Algologici, 1883.

Wille — Pringsheim's Jahrb. wiss. Bot., 1887, pp. 426 and 484.
Wildeman— C. R. Soc. Roy. Bot. Belgique, 1888, p. 140.
De Toni— Notarisia, 1888, p. 581.

Class XVI.— Multinucleatae.

In this newly-constituted group are included the four orders of
Siphoneae, Botrydiaceae, Dasycladaecea, and Siphonocladaceae, the near
relationship of which to one another is scarcely doubtful, although the
first displays sexual reproduction of a high type, with strongly differ-
entiated antherids and oogones, which are not found in the other
orders. All the orders nre also propagated non-sexually by zoospores.
Their common characteristic is. the extraordinary development in size

MUL TJNUCLEA T& 28 1

of the single cell, which nowhere else in the vegetable kingdom attains
anything like so great dimensions. Under ordinary conditions the in-
dividual is entirely unseptate, except where it is about to form repro-
ductive bodies, whether sexual or non-sexual. The very large number
of nuclei is universal in the Siphonocladaceae ; and, although their
occurrence in the Siphonese rests chiefly on the evidence of Schmitz,
there can be little doubt that this order also shares in the peculiarity, which
does not lead on to cell-division, as in the groups of algae already
described ; and this must clearly be regarded as indicative of a lower or
more ancestral type of structure. Whether the Siphonocladaceae and
Dasycladaceae are an earlier form leading up to the Siphoneae, or
whether they have been derived from the latter by retrogression, indi-
cated by the suppression of the sexual organs, is uncertain, though the
probability appears to be in favour of the latter hypothesis.

ORDER i. — SIPHONED (CCELOBLASTTE).

The thallus is in this family ordinarily unicellular, although often
copiously branched, until the commencement of the formation of the
organs of vegetative propagation or of sexual reproduction.

In the genus Vaucheria DC, which alone represents this order, the
plant consists, when in a non-reproductive state, of a single elongated cell
of a pale green colour, branching in various ways, sometimes as much
as a foot in length, increasing by apical growth. Maupas (Comptes
Rendus, I.e.) and Schmitz (Sitzber. Niederrhein. Gesell., 1879) state
that each tube contains a large number of nuclei. The non-sexual
organs of propagation are of two kinds, motionless resting-spores and
motile zoospores. The former are produced simply by the abstriction of
ends of particular branches, which swell up to an oval form, become
cut off from the rest of the tube by a septum, contract, and finally
develop a new cell-wall within the old one, thus affording an illustration
of the formation of a new cell by rejuvenescence. This process takes
place especially as a result of injury to the thallus. In some cases
the newly-formed spore is set free simply by the absorption of the
original cell-wall, and falls off with the remains of the mother-cell still
attached to it, germinating after a few days ; or it is thrown out with a
jerk, and goes through a period of rest as a hypnospore before germinat-
ing. Another method is the swelling up to a considerable size of
certain branches, which separate at the base, and put out at once one
or more germinating tubes. The zoospores are among the most beauti-
ful of those of any class of Algae, being of considerable size, and entirely
surrounded by a fringe of fine cilia. In their formation the extremity

282

ALG&

of a branch is cut off by a septum as a zoosporange\ the dark green en-
dochrome in it gradually contracts into an ellipsoidal form, finally forcing
its way out by the rupture of the cell-wall at the apex of the branch.
The rotatory motion imparted to the zoospore by its fringe of cilia
begins even within the mother-cell. During its escape it sometimes
gets nipped in two by the pressure of the cell-wall, and each half then
becomes a zoospore, one inside, the other outside, the wall of the
mother-cell. The zoospores are formed in the night and escape in the
morning ; their spontaneous motion lasts for a period varying from less
than a minute to several hours. As soon as they have come to rest they

Off

E

osp

FIG. 248. — Vaucheria sessilis Vauch. A, J>, formation of antherids and oogones ; /i, male
branch ; a, antherid ; og, oogune. C, oogone opening and ejecting drop of mucilage, si.
D, antherozoids. £, antherozoids entering oogone. F : a, empty antherid ; osp, oogone
with fertilised oosperm (magnified). (After Pringsheim and Goebel.)

lose their cilia, and become invested by a cell- wall of cellulose ; their
germination begins during the same day or the following night. The
spore puts out either one or two germinating tubes, formed by its inner
roat or endospore bursting through the outer coat or exospore ; and
the new plant usually fixes itself by a rhizoid- or root -like organ of
attachment.

The sexual reproductive organs of Vaucheria, oogones and antherids,
originate as lateral protuberances on a filament, sometimes even on

MUL TIN UC LEA T.E

283

the germinating tube which springs directly from a zoospore. Most of
the species are monoecious, and the oogones and antherids are usually
found very near together. The antherids are the terminal portions of
slender branches, in some species straight, in others curved and more
or less resembling horns or hooks. They contain but little chlorophyll,
and the protoplasm breaks up into a large number of biciliated anthero-
zoids, which escape through the ruptured apex. The two cilia are of
unequal length, and point, one backwards, the other forwards. The
oogones arise as thick swellings, often somewhat resembling a bird's
head in shape, and are densely filled with chlorophyll ; they are finally
cut off from the rest of the tube by a septum. The coarsely-granular
green protoplasm collects in the centre of the oogone, leaving a colour-
less portion at the apex which corresponds to the beak of the bird.
Here the oogone opens, and a colourless drop of mucilage is sometimes
expelled. When the greater part
of the contents has contracted
into an oosphere, a number of
.antherozoids force their way in
through the open mouth of the
oogone, and impregnate the
oosphere by coalescing with it.
The oosperm, resulting when the
impregnated oosphere has be-
come invested by a cell-wall of
cellulose, assumes a red or brown
•colour, and passes through a
period of rest as a hypnosperm.
On germination several non-
sexual generations are pro-
duced, ending in the formation
of sexual organs. The formation of antherids and oogones begins
in the evening and is completed the next morning ; fertilisation being
usually accomplished between 10 A.M. and 4 P.M. It is most usual for
zoospores to be formed on parts of the thallus which are completely
submerged in water ; while the sexual organs are more commonly found
when the plant grows on moist ground or on the margin of a ditch.

Several species of Vaucheria are frequent in fresh, while some occur
.also in brackish or salt water ; others abound on moist or shady ground,
being especially common in flower-pots or on neglected gravel-paths,
where they form light green tufts or thick mats. The normally uni-
cellular thallus is liable to segmentation as the result of injury ; and,
even when uninjured, has a tendency to become septated by thick

FIG. 249. — Vaucheria dichotoma Lyng. A,
oogone; £, germinating spore (x 200). (After
Woronin.)

284

ALGsE

gelatinous walls. In this condition it was formerly described as a
distinct organism under the name Gongrosira. These gongrosira-cells,
when isolated, develop into ordinary plants ; or sometimes their proto-
plasm breaks up into fragments which escape from the cell-wall and
move about with an amoeboid motion. These invest themselves after
a time with a cell-wall and remain in this condition as spherical resting-
cells or hypnospores, finally developing into ordinary filaments. Wille
has, however, shown (Bot. Centralblatt, vol. xvi., 1883, p. 162) that
the organisms formerly grouped under Gongrosira are states of algae
belonging to a number of widely separated genera, such as Trentepohlia

(Chroolepus), Botrydium, Stigeoclo-
nium, &c. In some species of Vau-
cheria the filaments have a tendency
to branch copiously at the extremity,
the branches interweaving into a
ball. Several species are liable to<
the formation of singular galls caused
oy the attacks of a rotifer belonging,
to the genus Notommata (Benko,
Bot. Centralbl., vol. xiv., 1883, p. i).
Phyllosiphon (Kiihn) is a truly-
parasitic chlorophyllous alga occur-
ring in the south of Europe within the
leaves of Arisarum vulgare, the posi-
tion of which appears to be near this
family. The single cell contains a
large number of nuclei ; the mode of
reproduction is unknown (Kiihn, Sitz-
ber. Naturf. Gesell. Halle, 1878 ; Just.,
Bot. Zeit., 1882, p. 2 etseq. ; Schmitz,
id., 1882, p. 523 et seq. ; Franke,
Jahrber. Schles. Gesell., 1883, p. 195).
Endodonium (Franke) (Cohn's
Beitrage, 1883, p. 365), Chlorochy-
trium (Cohn), Endosphcera (Klebs),
and Phyllobium (Klebs) (Bot. Zeit.,,
1 88 1, p. 249 et seq.} are green parasitic algae found within the cells of the
leaves of various land and aquatic plants ; and, in the case of Chloro-
chytrium, also on animals (Bot. Zeit, 1885, p. 605). They are stated to
produce megazoospores, which germinate directly, and microzoospores
or zoogametes, which germinate only after conjugation ; but their exact
position is altogether uncertain.

FIG. 250. — Botrydium grannlatuin Wallr.
s, vesicular portion ; ~7t', rhizoids ( x 30).
(After Woronin.)

MUL TINUCLEA T^E 285

LITERATURE.

Thuret— Ann. Sc. Nat. (Bot.), xiv., 1850, p. 214.
Pringsheim — Member. Akad. Berlin, 1856, p. 225 (Quart. Journ. Micros. Sc., 1856,

p. 63).

Schenk— Wurzburg Verhandl., viii., 1858, p. 235.
"Walz— Pringsheim's Jahrb. wiss. Bot., 1866, p. 127.
Solms-Laubach— Bot. Zeit., 1867, p. 361.
AVoronin- Bot. Zeit., 1869, p. 137 et seq.
Nordstedt— Bot. Notiser, 1878, p. 176; and 1879, p. 177 ; and Scottish Naturalist,

1886.
Stahl— Bot. Zeit., 1879, p. 129.

ORDER 2.— BOTRYDIACE^E.

This order consists at present of only a single genus, Botryditim Wallr.,
represented by the single species B. granulatum (Wallr.), differing widely
from Vaucheria in its mode of reproduction. This remarkable organism
forms minute green blobs on wet clayey ground or in dried-up pools, and
is attached to the soil by branching root-like rhizoids. The young plant
consists of a single nearly spherical cell, branched hyaline prolongations
of which constitute the rhizoids, while in the upper swollen part the proto-
plasm forms a hyaline parietal layer containing chlorophyll. From this
protoplasm are ultimately produced a number of zoospores, each pro-
vided with only a single cilium, which germinate directly on the damp
soil after becoming invested with a double cell-wall of cellulose. If the
zoosporange is exposed to drought, the vesicular portion shrivels up and
the chlorophyll is driven into the underground portion, which then divides
into a number of green cells. These may germinate in three different
ways: — (i) Each cell becomes an underground zoosporange, producing
zoospores of the ordinary kind ; or (2) each cell may develop into an
ordinary vegetative plant; or (3) each cell becomes a hypnosporange,
closely resembling the ordinary vegetative plant, with a vesicular portion
above the surface, and hyaline rhizoids, but of an olive-green colour;
these may retain their vitality for a whole year and then produce zoo-
spores. The ordinary vegetative plant may also, under certain con-
ditions, break up into a number of resting-spores, of a brownish red
colour, which have been described as species of Protococcus. These
may either give birth to zoospores of the ordinary kind or to biciliated
zoogametes which conjugate in pairs, or sometimes in larger numbers.
The resulting zygosperm ('isospore' of Ros*tafinski) soon rounds itself

off and germinates.

LITERATURE.

Janczewski et Rostafinski— Mem. Soc. Sc. Nat. Cherbourg, 1874, p. 273.
Janczewski u. Woronin— Bot. Zeit., 1877, p. 649 et seq.

286

ALGsE

ORDER 3. — DASYCLADACE/E.

The Dasycladaceae are clearly distinguished from the other orders of
the class by their verticillate branches and their external sporanges. In
Acetabularia Lmx. the thallus has the form of a small hymenomycetous
fungus with a hemispherical or
funnel-shaped cap or ' pileus '
at the summit of a cylindrical
* stipe ' or stalk. From the
lower end of the stalk proceed
a number of root-like branches
which fix the plant to the sub-
stratum. The whole plant con-
sists of a single ramifying cell,

FIG. 251. — Acetctbnlaria mediterranea.
Lmx. (natural siza).

the walls of which are, when
mature, permeated by calcium
carbonate. The cap is divided
by regular radial projections
into a large number of cham-
bers of nearly equal size, which
are in communication with one
another above the insertion of
the stalk. The upper part of
the thallus perishes at the end of the season, while the lower portion
is perennial. After a number of sterile thalli have been produced, a
fertile thallus appears, similar in structure to the sterile ones. In the
chambers of the cap of this thallus are produced the zoosporanges, a large
number in each chamber, of an ellipsoidal form, and furnished at one
end With a lid, which subsequently becomes detached. When mature
the protoplasm of the sporange breaks up into a number of swarm- spores,

FIG. 252. — A. mediterranean 7, cap (magnified) ;
«, scars of branches ; r, rudimentary whorl of branches ;
?v, ring above the cap ; v, depressed apex ( x 4).
//, sporange with lid (x 120). ///, the same, show-
ing the escape of the swarm-spores (x 120). IV,
conjugation of zoogametes. V, VI, lower part of
stem, showing rhizoids, b. VII r, plant germinating
from a zygosperm. VIII, origin of branches at
summit of the stem(x 120). IX, at a later stage
(x 90). (After de Bary and Strasburger.)

MUL TIN UC LEA T^E

287

which escape into the surrounding water by the removal of the lid. It

would appear from de Bary and Strasburger's observations that some

of these swarm-spores germinate directly, while others conjugate to form

a zygosperm; but that conjugation never takes place between zooga-

metes from the same spo-

range. One species of Ace-

tabularia is a native of the

Mediterranean ; the rest are

tropical. In Dasycladus Ag.

the spherical zoosporanges

stand singly at the apex of

verticillate branches, and are

surrounded by branchlets of

the second order. The bicili-

ated zoospores or zoogametes

are of one kind only, and are

flattened and heart-shaped.

Those from the same plant show no disposition to conjugate ; but as

soon as those from different plants are brought together, true zygosperms

are formed. In Neomeris Lmx. the surface consists of a large number

of usually hexagonal facets, and is covered with deciduous hairs. The

FIG. 253. — Dasycladus clav&formis Ag. a. natural size ;
b, piece of branch of a whorl with a zoosporange ( x 50).
(After Hauck and Derbes and Solier )

FIG. 254. — Neomeris Kelleri Cram. ; transverse section through tube, a, insertion of
the branches ; b, £, primary branches ; c, central secondary branch or zoosporange ;
d, elongated lateral secondary branches (x 40). (After Cramer.)

very large axial cell is always simple ; the lateral branches again divide
into three branchlets, of which the central one is ovoid and fertile, the
two lateral ones greatly elongated and sterile. The fertile branch is a

288

ALG^E

zoosporange, no conjugation of swarm-spores having been observed.
Klein (Bot. Zeit, 1880, p. 782) has detected fine proteinaceous crystal-
loids in Dasycladus (Ag.) and other allied forms. To this family belong
also Polyphysa (Lmx.), Cymopolia (Lmx.), and some other genera.

FIG. 255. — Polyphysa penlculits R. ,
Br., with whorl of zoosporanges, sp
(magnified). (After Agardh.)

FIG. 256. — Caulerpa prolifera. Lmx. (natural size). (After Reinke.)

ORDER 4. — SIPHONOCLADACE^E.

This order comprises a number of very remarkable green algae, mostly
inhabitants of warm and shallow seas, characterised by the thallus con-
sisting of a single cell which is often of very great size and much branched,
differentiated into a root-like and stem-like portion. The undivided cell
very commonly contains a large number of nuclei ; and the cell-wall is

MUL T1NUCLEA T.-E

289

iU.

often strongly encrusted with calcium carbonate. In several of the
genera of Siphonocladaceae, but little is at present known as to the mode
of reproduction ; and until this has been more fully ascertained, their
true affinities are uncertain ; and it is possible that the order, as at
present constituted, includes forms which are not nearly allied to one
another. In none of the genera is a fertilisation of oogones by anthero-
zoids known, similar to that of Vaucheria. The ordinary mode of re-
production appears to be by zoospores which germinate directly without
conjugation. Other modes of non-sexual propagation occur in some of
the genera, by 'propagules' or by ' prolification.' The following are
some of the more remarkable forms included in the group.

The CAULERPE^E include the single genus Caulerpa Lmx., cha-
racterised by its greatly-branched thallus of
remarkably leaf-like appearance. Very little is
known about the mode of reproduction. The
ordinary process of propagation appears to be
by ' prolification ' from all parts, the so-called
'roots,' ' stem,' and 'leaves.' Within the tube
are solid branched layers of cellulose stretching
from wall to wall, and forming a closed net. It
often covers enormous tracts of the shore
between high and low water marks with a green
coating.

The VALONIACE^E (Valonia, Gin., Siphono-
cladus, Schr., Struvea, Sond., Anadyomene,
Lmx., &c.) are an ill-defined family, in which
the cell is frequently swollen up into a bladder-
like structure ; the mode of propagation is ap-
parently by non-sexual zoospores. To these
are closely allied the UDOTEACE^E (Avrainvillea,
Dene., Penicillus, Ktz., Udotea, Lmx., Halimeda, Lmx., &c.). Halimeda
has a remarkable Opuntia-like appearance, from the single cell consisting
of a large number of pear-shaped branches, each connected with the
one below it by a narrow base, and the whole encrusted by calcium
carbonate.

In the BRYOPSIDE^: (Bryopsis, Lmx., Derbesia, Sol.) and SPON-
GODIE^E (Codium, Stackh.) the thallus is not encrusted with calcium
carbonate. Codium forms a spongy spherical or cylindrical floating mass,
of considerable size, consisting of branched tubes. It is apparently pro-
pagated by zoospores. In Bryopsis Lmx. the thallus has a branched
root-like colourless portion, and an erect cylindrical stem, the upper half
of which branches into pinnate leaf-like ramifications with limited apical

U

FIG. 257. — Valonia macrophysa-
Ktz. (natural size). (After
Hauck.)

290 ALG&

growth ; in these branches zoospores are formed ; conjugation between
them has not actually been observed. External organs of reproduction
known as ' conceptacles ' have also been described on several species
of Bryopsis, which have been conjectured to be true sexual organs,
whether male or female, but their true structure and functions are alto-
gether obscure. If, as is probable, some of the swarm-spores of Codium

FIG. 258. ~ Halimeda. Tuna Lmx. a, natural size ; b, portion with zoosporanges ( x 50).
(After Derbes et Solier.)

and Bryopsis are in reality conjugating zoogametes, this would bring
these two families into close relationship to the Botrydiaceae ; and this
is probably the nearest affinity of the latter group. Spongocladia
(Aresch.), described >by Zanardini as belonging to the Siphoneae, appears
to be a genus more nearly allied to Cladophora, in which the filaments
are remarkably infested with sponge-spicules.

LITERATURE.

(Dasycladaceo: and Siphonocladacea. )

Nageli— In Zeitschr. wiss. Bot. , 1844.

Derbes & Solier— Ann. Sc. Nat. (Bot.), 1850, p. 240.

M UL T1NUCLEA T^E 291

Braun—Verj tingung in der Natur, 1851, p. 136 (Ray Soc., Bot. and Phys. Mem.,

Woronin— Ann. Sc. Nat. (Bot.), xvi., 1862, p. 200.

Pringsheim — Member. Berlin Akad., 1871, p. 240.

Arcangeli — Nuov. Giorn. Bot. Ital., 1874, p. 174.

De Bary u. Strasburger — (Acetabularia) Bot. Zeit., p. 713 et seq.

Cornu — Compt. Rend., Ixxxix., 1879, p. 1049.

Schmitz — Sitzber. Niederrhein. Gesell., 1879 and 1881.

Berthold— Bot. Zeit., 1880, p. 648 ; and Mittheil. Zool. Stat. Neapel, 1880, p. 72.

Murray — (Rhipilia Ktz. =Avrainvillea Dene.) Trans. Linn. Soc., ii., 1886, p. 225

Wakker— (Caulerpa), Versl. Akad. Weten. Amsterdam, 1886, p. 251 ; and 1887,

p. 251.

Agardh — Till Algernes Systematik, Siphoneae, 1887.

Cramer — Ueber die verticillirten Siphoneen (Neomeris und Cymopolia), 1887.
Noll— Bot. Zeit., 1887, p. 473.
Murray and Boodle — (Struvea) Ann. of Bot., ii. , 1888.

Class XVII.— Ccenobieae.

In this class are included a small number of minute (mostly micro-
scopic) fresh-water organisms, characterised by the cells being associated
together into a cxnobe, i.e. into a colony of more or less equivalent cells
resulting from the division of a common mother-cell. As this division
always takes the form of repeated bipartition, the number of cells con-
stituting a colony is necessarily, when perfect, a power of 2, viz. 4, 8, 16, 32,
64, &c. The cells constituting the coenobe are more or less imbedded
in a gelatinous envelope, which is sometimes enclosed in a membrane
common to the whole colony ; in the higher forms the cells, or some of
them, are ciliated, the cilia protruding through the enveloping mem-
brane, and the colony moves about in the water with very great activity ;
the lower forms are not ciliated, but the colony is nevertheless endowed
with a very considerable power of motion. The ccenobe is always of
an exceedingly beautiful regular form, spherical, or less often discoid
or cubical, or, in the Hyo^rodictyeae, in the form af a net. The five
orders of which it is composed, the Sorastreae, Pandorineas, Pediastreae.
Hydrodictyeae, and Volvocineae, form a series of ascending develop-
ment. Very little is known about the reproduction of the first ; the
Pandorineae, Pediastreae, and Hydrodictyeae multiply by the conjugation
of zoogametes ; while in the Volvocineae, which represent the highest
type attained by organisms of the coenobe type, the mode of sexual
reproduction is much more complicated, the male and female reproduc-
tive cells being separately formed in distinct antherids and oogones.

U 2

292

ORDER i. — VOLVOCINE^E.

The well-known Volvo x glob ator L. may be taken as a type of this
interesting family. This organism is not uncommon in clear pools, and
is visible to the naked eye as a minute pals-green globule, about ^
inch in diameter, rolling through the water, the motion being due to
numerous colourless cilia projecting from its surfa'ce. It is one of the
most beautiful objects that can be observed under the microscope.

Under a sufficiently high power of the microscope, Volvox is seen to
be a membranous transparent hollow sac studded with green points ;
in the interior are darker green globules, the original number of which
is apparently always eight. The green peripheral corpuscles or swarm-
cells are each provided with a pair of vibratile cilia, which protrude
through the enveloping sac ; they vary in form, but are usually some-
what pear-shaped, and contain a starch-granule, a reddish-brown
pigment-spot, and one or two contractile vacuoles, the cilia being borne
at the narrow anterior hyaline end. The internal green globules are
young individuals formed within the parent, which thus constitutes a
colony or cainobe ; but all the cells which make up the colony are not
equivalent as respects their reproductive power. The larger number of
the cells are sterile or purely vegetative, while a much smaller number,,
developed at particular spots in the colony, are generative, these again
being differentiated into non-sexual propagative and male and female
reproductive cells. The sterile cells are the peripheral or swarm-cells,
2-3 mm. in diameter, which precisely resemble in structure Chlamydo-
coccus, the motile stage of Pleurococcus, or the zoospores of many
algae. The gelatinous membrane which envelopes each of these swarm-
cells is pierced by a number of canals, which lie nearly in one plane,
and which are filled by green or colourless extensions of the proto-
plasmic interior. Since the canals of adjoining swarm-cells correspond
in position, they appear as if they were all connected together by a
network of fine reticulations. The membrane is also perforated by two
pores, through which the vibratile cilia protrude into the surrounding
water. These bodies present the unusual pl^nomenon of cells endowed
with spontaneous power of motion, which have, nevertheless, as far as is
known, no reproductive function, and are therefore not properly called
zoospores. The non-sexual propagative cells, zoospores or partheno-
spores, are similar in structure to the sterile swarm-cells, but from two
to three times their diameter. Very early in the development of the
young colony the contents of the mother-cells of the zoospores begin
to divide by repeated bipartition, all in the same colony being usually
at the same stage of development at one time ; the daughter-colonies,,

CCENOBIEsE 293

or zoosporanges thus formed have the form and appearance of the
parent-colony, each segment possessing a single chlorophyll-body, which
contains starch. Ultimately, while still within the parent-colony, vibra-
tile cilia are developed in its peripheral segments, which cause it to
rotate, clothed at first by a transparent mucilaginous envelope, which
it at length breaks through. The number of colonies of zoospores thus
produced within the parent-colony is normally eight, resulting appa-
rently from the eight cells into which the parent-colony breaks up on
its third segmentation. The young colonies complete their growth in a
few days, attaining a diameter of from 100 to 150 mm., and have by
this time absorbed the greater part of the chlorophyll and starch of the
parent-colony, from which they finally escape.

Volvox may multiply by this non-sexual mode of propagation for
several successive generations, and these are succeeded by a sexual mode
of reproduction. The male and female reproductive cells are formed
either in the same or in different colonies ; or, according to other ob-
servers, the so-called * dioecious ' species are in reality proterandrous,
producing antherids at an earlier, oogones at a later stage. While the
non-sexual propagation by zoospores goes on through the whole year, the
sexual cells appear to be produced only in the autumn. The oogones are
at first quite indistinguishable from the non-sexual cells except in size,
but are much more numerous, and soon manifest a distinction from the
fact that they do not divide. On their first appearance they are about
three times the size of the sterile cells ; their protoplasm increases
rapidly, and becomes of a dark-green colour, from copious production
of chlorophyll. They have at first a frothy appearance from the forma-
tion of vacuoles, but afterwards appear to be densely filled with the
dark-green endochrome. They soon become flask-shaped, the narrow
end touching the periphery of the colony, and the larger end hanging
free inside ; but, when ready for impregnation, round themselves off
into a spherical form, their contents being an oosphere enveloped by a
gelatinous membrane. The antherids present at first sight a still closer
resemblance to zoospore-colonies at an early stage, but are lighter in
colour from containing a smaller quantity of chlorophyll. Their con-
tents soon begin to divide, but in two directions only, the young colony
thus developing into a plate instead of a sphere of segments enveloped
in a gelatinous coating. The colony ultimately resolves itself into a
bundle of antherozoids, naked fusiform masses of protoplasm, each
consisting of a thicker but elongated body, in which the chlorophyll has
been transformed into a yellow-brown pigment, and a slender colourless
beak, with a pigment-spot at its base, where also are attached on one
side two very long cilia. About the time when the oogones, with their

294

©

FIG. 259. — Volvox globafor_ L. A, colony, sexual generation; a, antherids; b, oogones ; c,
oospheres. B, ciliated peripheral cells. D, antherid. £, F, antherozoids. G, oogone containing
mature oosphere and antherozoids. ff, mature oosperm. C, mode of division of parent-cell of a
zoosporange (all highly magnified). (After Cohn.)

C&NQB1EM 295

oospheres, are mature, the movement of the cilia begins to set the entire
antherid in motion ; but it shortly breaks up, and the separate anthero-
zoids are seen in rapid motion within their gelatinous envelope, which
they ultimately break through, and then move about rapidly in all
directions within the cavity of the parent-colony. They assemble in
large numbers round the oogones, and some of them finally penetrate
through the gelatinous membranes of these organs, and coalesce with
the oospheres. The number of sexual reproductive colonies within a
parent-colony varies greatly ; Cohn has observed five or six male and
about forty female. The impregnated oosphere now becomes an oosperm
by the development of a cell-wall of cellulose, which is at first single
and smooth, but becomes subsequently differentiated into three distinct
layers, of which the two inner ones are smooth, while the outermost
becomes ultimately covered with conical or warty elevations, giving it
on section a stellate appearance. The chlorophyll of the oosperms
gradually disappears, and is replaced by an orange-red pigment dissolved
in oil, giving a red tinge to the entire organism as seen by the naked
eye. Soon after the maturity of the oosperms, the parent-colony breaks
up, and the peripheral swarm-cells escape from the combination and
swim about freely in the water ; their further history has not been traced.
The orange-yellow oosperms sink to the bottom, and there hibernate as
hypno sperms. Their contents are said to break up into eight Volvox-
colonies, which ultimately escape by the rupture of the outer and absorp-
tion of the inner coats of the oosperm, and swarm about in the water.

In Eudorina Ehrb. the ccenobe is a hollow ellipsoid body, consisting
of usually 16 or 32 cells enclosed in a gelatinous envelope, each pro-
vided with two long cilia which protrude through canals in the envelope,
and a red pigment-spot. Daughter-colonies are formed non-sexually
within the parent-colony by repeated bipartition of its cells, the cells of
the daughter-colony being arranged in a disc. The male and female
reproductive bodies are formed in special daughter-colonies which may
be termed antherids and oogones respectively ; the oospheres contained
in the oogones are each provided with two cilia, and are therefore true
zoospheres ; the antherozoids, which closely resemble those of Volvox,
swarm round the oogones until their cilia become entangled in those of
the zoospheres ; they then force their way into the gelatinous envelope
of the oospheres, and finally coalesce with them.

Volvox and Eudorina are regarded by Ehrenberg and Stein as
belonging to the Flagellate Infusoria.

Under the name of Scyamina, Van Tieghem (Bull. Soc. Bot. France,
1880, p. 200) describes a singular blackish organism found on the surface
of ponds, which he regards as a genus of Volvocineae destitute of
chlorophyll.

296 ALG^E

LITERATURE.

Ehrenberg — Die Infusionsthierchen, 1838.
Busk — Trans. Micros. Soc., 1853, p. 31.
Cohn— Jahrber. Schles. Gesell., 1856, p. 237 ; and Beitrage, i., 1875, Heft 3, p. 93

(Pop. Sc. Rev., 1878, p. 225).

Carte.r-(Eudorina) Ann. Nat. Hist., 1858, p. 237 ; and 1859, p. i.
Braun — Bot. Zeit., 1875, p. 189.

Stein — Der Organismus der Infusionsthiere, part iii., 1878.
Henneguy— Journ. d. Micrographie, 1878, p. 485.
Maupas— Compt. Rend., Ixxxix., 1879, p. 129.
Kirchner in Conn's Beitrage, iii., 1879.

ORDER 2. — HYDRODICTYE^:.

The relationship of the Hydrodictyeae to the other families of Cceno-
bieae is somewhat obscure. They differ from them in the form of the
ccenobe, which, instead of being minute and globular, ellipsoidal or tabu-
lar, is of considerable size, and presents the appearance of a net. The
only known mode of reproduction is by the conjugation of zoogametes.

As here constituted the order is limited to the single genus Hydro-
dictyon Roth, one species of wh'ich is moderately common in ponds
and ditches, and is known under the name of * water-net.' When the
plant is mature, the ccenobe consists of a sac-like net several centimetres
in length, composed of a great number of cylindrical cells united at their
ends so as to form a 4- or 6-cornered mesh. The ordinary mode of pro-
pagation consists in the protoplasm of one of the cells breaking up into
from 7,000 to 20,000 megazoospores, each furnished with four cilia, which
move about with a trembling motion within the zoosporange, come to
rest in the course of half an hour, and then arrange themselves in such
a way that, by their elongation, they again form a net of the original
kind, which is set free by the absorption of the wall of the mother- cell,
and attains, in the course of three or four weeks, the size of the mother-
colony. In other cells of the mature net the protoplasm breaks up into
from 30,000 to 40,000 smaller swarm-cells or zoogametes, furnished
with only two cilia, which at once leave the garnet ange and swarm
about for some hours. Conjugation between these has been observed to
take place even within the gametange, more than two sometimes uniting
together. The resulting zygosperm retains its green colour, and invests
itself with a firm cell-wall. After remaining for several months at rest
as a hypnosperm, it begins to grow slowly, and, when it has attained
a considerable size, its contents break up into two or four mega-
zoospores, which come to rest after a few minutes, and assume a pecu-
liar angular form when they have attained a considerable size, putting
out horn-like appendages. In each of these polyhedra the green parietal

CCENOBlEjE

297

protoplasm again breaks up into zoospores, which swarm about for twenty
or forty minutes within a sac which protrudes out of the protoplasm.
When they come to rest, they arrange themselves within the sac into a
small net consisting of from 200 to 300 cells, which gradually grows to

FIG. 260. — Hydrodictycn ntricu?atum Roth. A, net (natural size). B, mesh (x 10), C, megazoo
sporange (x 300). D, megazoospores (x 600). £, gametange with zocgametes(x 300). (After
Cohn.)

one of the ordinary size. In some of the polyhedra smaller and more
numerous microzoospores are formed ; but they also appear to unite
again into a net without displaying sexual functions.

LITERATURE.

Nageli— Gattungen einzelliger Algen, 1849, p. 92.

Braun— Verjiingung in der Natur, 1851 (Ray Soc. , Bot. and Phys. Mem., 1853) ; and

Algoe unicellulares, 1855.
Pringsheim— Monber. Berl. Akad., 1860, p. 775 (Quart. Journ. Micr.'Sc., 1862, pp.

54 and 104).

298

ALGsE

ORDER 3. — PEDIASTRE^E.

The Pediastreae are most nearly allied to the Hydrodictyeae in their
mode of reproduction. Of the typical genus Pediastrum Mey., several
species are very common in fresh water, whether stagnant or running,
attached in the form of minute (usually microscopic) discs to other algae
or water-plants, or swimming free. Each disc is of a regular symmetrical

FIG. 261.— Pediastrum integrnm Nag. ~A, younger, 8, older ccenobe (x 300). C, portion
of older coenobe showing resting -cell, r ( x 600). (From nature.)

form, usually elliptical, and consists most often of 8, 1 6, or 32 cells, or
some larger number which is probably always, when perfect, a power of
two. The ccenobe is invested in a very thin gelatinous envelope, and
the peripheral cells have commonly horn-like or crescent-shaped appen-
dages. Pediastrum is multiplied either by non-sexual propagation or

by sexual reproduction. In the former
case one of the ordinary vegetative cells

>*^ ^ *? — i ^

vV5^ f B \ becomes a zoosporange, its protoplasm

Jifjf I \\ \ breaking up into a number of nearly

^^•^ I \( I globular megazoospores each furnished

with two very fine and inconspicuous
cilia, which, after swarming about for a
time, lose their cilia and arrange them-
selves in the form of a plate, which
then escapes from the zoosporange in-
vested in mucilage, and develops into

a new Pediastrum-disc. Others of the cells become gametanges, the
contents dividing in the same way into zoogametes of an ovoid or
pear-shaped form, which conjugate after escaping separately from the
mother-cell, but apparently only with those from other gametanges. The
peripheral cells of the ccenobe appear to have a tendency to develop
into resting-spores.

FIG. 262. — A, polyhedra of Pediastrnm
( x 55°)' -B, formation of Pediastrum-
disc within polyhedra (x 550). (After
Askenasy.)

CCENOBIE^E 299

Askenasy has observed the development of the Pediastrum-coenobe
by another method from the polyhedra form, previously regarded as
a distinct genus under the name Polyedrium (Nag.). In this form each
individual consists of a minute flat angular cell often provided with
spines or hook-like processes. From this a Pediastrum-disc is developed
in precisely the same way as from a Pediastrum-cell. The cell-contents
break up into a number of megazoospores, which escape in the form of
a plate after swarming about for a time ; then, losing their cilia, and
placing themselves in a plane side by side, develop into an ordinary
Pediastrum. Reinsch, on the other hand (Notarisia, 1888, p. 493),.
regards Polyedrium as the type of a separate family of Palmellaceae.

LITERATURE.

Nageli— Gattungen einzelliger Algen, 1849.

Braun — Verjiingung in der Natur, 1851 (Ray Soc., Bot. and Phys. Mem., 1853) ; and

Algae unicellulares, 1855.
Lagerheim — Bot. Centralbl. , xii., 1882, p. 33.
Askenasy— Ber. Deutsch. Bot. Gesell., 1888, p. 127.

ORDER 4. — PANDORINE^:.

In the higher genera of this order, Pandorina (Ehrb.), Gonium (Mull.),
and Stephanosphsera (Cohn), the individual is a spherical or tabular
ccenobe, the cells of which are united together by a gelatinous matrix
with a definite bounding-wall. With them are associated also some
unicellular organisms, Chlamydococcus (A. Br.) and Chlamydomonas
(Ehrb.), which may possibly be connected with them by a process of
degeneration. Whether isolated or associated, each cell possesses a
pair of whip-like vibratile cilia attached to the anterior pointed end, by
means of which it is rapidly propelled through the water ; in the case
of the social genera these cilia project through the common gelatinous
envelope of the colony. Multiplication takes place either non-sexually
by simple subdivision of the cells of a colony, or sexually by the union
of two (or occasionally more than two) zoogametes into a resting zygo-
sperm. A characteristic feature of the family is the formation of a
colony of cells within each cell in the mother-colony. The organisms
here included were described by Ehrenberg as constituting a family of
Infusorial Animalcules. They live, associated with larger algae, in fresh
water, running or stagnant, often in such quantities as to impart to it a
green colour. The family closely approaches Volvocineoe through
Eudorina.

Of the unicellular Pandorineae Chlamydomonas Ehrb. may be taken
as a type. In the form in which it is known under this name, it

300 ALGsE

consists simply of a single motile primordial cell, in other words, of a
zoospore or swarm-cell. These are megazoospores, half as long again
as broad, each with two contractile vacuoles, a lateral red pigment-spot,
and two long cilia ; in the posterior half is a nucleus. After the con-
clusion of the period of swarming, these zoospores become invested
with cellulose, and, after a long period of rest as hypnospores, multiply
non-sexually by division into four — less often into two. According to
Rostafinski sexual reproduction takes place by one of these mega-
zoospores dividing, by successive bipartitions, into eight daughter-cells,
which are then microzoospores — or, more correctly, zoogametes. These
have a longish almost elliptical form, and a light green colour, one
nucleus, a red pigment-spot, and four cilia. They are distinguished
from the true zoospores, not only by their smaller size, but also by the
large colourless extremity in place of the two contractile vacuoles. They
swarm out, and soon begin to conjugate in pairs, coming into contact
by their colourless extremities, and coalescing into a single cell, the
ends which bear the cilia at the same time rounding off and approxi-
mating. This body has now eight cilia and two lateral pigment-spots ;
ultimately the eight cilia disappear, and a zygosperm is formed, which
multiplies by simple division without swarming. Dangeard finds in
Chlamydomonas pulvisculus (Mull.) a differentiation of male and female
gametes, the latter being considerably larger than the former. In C.
Morieri (Dang.) he describes a peculiar mode of conjugation of zooga-
metes, which he compares to that of Spirogyra.

Chlamydococcus A. Br. presents a similar life-history ; and, according
to some observers, the organisms known as Pleurococcus, Glceocystis,
and others usually included under Protococcaceae, are identical with the
resting conditions of Chlamydomonas ; and, under suitable conditions,
can be made to produce biciliated zoospores with two contractile
vacuoles and a nucleus.

Under the Volvocinese, and near to Chlamydomonas, Dangeard
(Ann. Sc. Nat., vii., 1888, p. 105) and Stein include also Chlorogonium
(Ehrbl);

Among the most interesting of the social Pandorineae is Pandorina
Ehrb.. Each family or ccenobe consists of sixteen cells closely crowded
together, and surrounded by a thin gelatinous envelope through which
the cilia protrude. Non-sexual multiplication is preceded, after the
colony has come to rest, by the absorption of the cilia in the sixteen
cells, each of which then breaks up into sixteen smaller cells ; and these
sixteen daughter-families are set free by the absorption of the gelatinous
envelope of the parent-colony; each becomes itself invested by a
gelatinous envelope, and grows to the size of the original parent-colony,

CCENOB1E&

having in the meantime developed two cilia from each of its cells.
Sexual reproduction takes place in the following way. Sixteen daughter-
families are first of all formed in the same manner, but the gelatinous
envelopes of the young colonies deliquesce, and the separate 256 (= 16
x 1 6) swarm-cells are set free as zoogametes. These vary in size, but
are always rounded and green at the posterior end, pointed hyaline and
with a red pigment-spot in front, where they bear two cilia. Among
the crowd of these swarm-cells — now swimming about freely — some,
irrespective of their relative size, approach one another in pairs, their
pointed anterior apices coming into contact, and they finally coalesce
into a body which has at first somewhat the shape of an hour-glass, but
gradually contracts into a sphere, in which the two pigment-spots and
the four cilia are still to be seen for a time, but soon disappear. This
whole process occupies about five minutes. The resulting zygosperm
is then a spherical cell enclosed in a cell-wall, which remains at rest for
some time as a hypnosperm, its green colour becoming changed to-
brick-red. If the dried-up hypnosperms are placed in water, they begin,
to germinate after about twenty-four hours. The outer layer of the
cell-wall is ruptured, an inner layer becomes gelatinous and swells up,
and the protoplasmic contents escape in the form of one, two, or three
large zoospores. Each of these, after a short period of swarming, loses
its cilia, surrounds itself with a
gelatinous envelope, and breaks
up, by successive bipartitions,

into sixteen portions, which
develop cilia, and form them-
selves into a new ccenobe.

A still more remarkable
succession of phenomena is
exhibited by Stephanosphcera
Cohn, a rare organism occur-
ring occasionally in the rain-
water which collects in the
hollows of large stones in
mountainous countries. In
addition to the process of
vegetative or non-sexual pro-
pagation, the cells belonging to a family, each of which possesses a red
pigment-spot, divide repeatedly into zoogametes, which ultimately
become free, and coalesce into resting zygosperms or hypnosperms.
Motionless balls, which are probably the result of this conjugation,
accumulate at the bottom of the water, and assume a red colour. After

FIG. 263. — Pandorina morum Fhrb. <z, swarming
coenobe ; b, c, swarm-cells ; d, e, coniugation of
zoogametes ; f, zygosperm ( x 500). (After Prings-
heim.)

302 ALG^E

these resting-cells have lain for some time dry, and then again been
flooded, the contents breakup into four or eight zDospores, which invest
themselves with a cell-wall, and, in the course of a single day, divide, by
successive bipartitions, into an eight-celled coenobe, which again, during
the next night, gives birth to eight motile families. The enclosed
primordial cells of Stephanosphaera are of a bright green colour, fusi-
form, and are attached to an equator of the investing membrane at
both ends by branched strings of protoplasm. The whole family
rotates on an axis at right angles to the plane which passes through
them all.

In Gonium Mull, the ccenobe is a tabular aggregation of cells moving
rapidly through the water by the aid of vibratile cilia. Its life-history
has not been fully followed out, and very little is known of its mode of
reproduction.

LITERATURE.

Henfrey— Trans. Micros. Soc. , 1856, p. 49.

Cohn& Wichura— (Stephanosphtera) Nova Acta Acad. Nat. Cur., xxvi. , Suppl. 1857,

p. i (Quart. Journ. Micros. Sc., 1858, p. 131).
Archer— Quart. Journ. Micros. Sc., 1865, pp. 166, 185.
Cienkowski— Bot. Zeit., 1865, p. 21.

Pringsheim— Monber. Berlin Akad. , 1869, p. 721 ; and Bot. Zeit., 1870, p. 265.
Yolten— Bot. Zeit., 1871, p. 383.

Rostafinski - Bot. Zeit., p. 785 ; and Mem. Soc. Sc. Nat. Cherbourg, 1875.
Goroshankin — Nachr. Gesell. Naturf. Moskau, 1875.
Hieronymus - Oesterr. Bot. Zeitschr., 1874, p. $i$etseq,
Reinhard- Arbeit. Naturf. Gesell. Charkoff, 1876.
Breal-Bull. Soc. Bot. France, 1 386, p. 238.
Dangeard— (Chlamydomonas) Ann. Sc. Nat., vii., 1888, p. 105.

ORDER 5. — SORASTRE^.

In this order are included a few genera distinguished by the ccenobe
being unciliated. In Sorastrum Ktz. the colony consists of a more or

FIG. 264. — Sorastrum spinu-
losum Nag. ( x 400). (After
Cooke.)

FIG. 265. — Ccclastrum citbicitm Nag.
(x 600). (From nature.)

less spherical aggregation of closely-packed, horned or bind, somewhat

CCENOBIE.-E 303

wedge-shaped cells ; in Selenastrum Reinsch the cells are crescent-
shaped ; in Calastrum Nag. the coenobe is spherical or cubical, com-
posed of a single layer of cells, and hollow in the centre. The species
are found occasionally in bog-pools ; although unciliated, the coenobe
swims freely in the water with a kind of rolling motion. Very little is
known with regard to the mode of reproduction ; no formation of zoo-
spores has been detected. Lagerheim describes the mode of formation
of a coenobe of Selenastrum by cell-division within the mother-coenobe.
The affinities of this very beautiful family are clearly with Botryococcus
among the Protococcaceae, and upwards with the Pandorineae. Scene -
desmus Mey. is very probably a primordial or a retrogressive member
of this family.

LITERATURE.

Nageli — Gattungen einzelliger Algen, 1849, p. 97.
Reinsch — Algen-Flora Mittel-Franken, 1867.
Lagerheim — Bot. Centralbl., xii. , 1882, p. 33.
Bennett— Journ. Micr. Soc., 1887, p. 13.

FOSSIL ALG.E.

All that we know of the relationships between the animal and vege-
table kingdoms leads us to the conclusion that the appearance of animal
life, both in fresh and in salt water, must have been preceded by that
of aquatic vegetation ; and it is almost certain that these primeval
vegetable organisms must have had a structure and mode of life which
would classify them under the head of Algae or of Schizophyceae.
But, since even the largest of these organisms would probably consist
entirely of cellular tissue, it is not to be anticipated that their remains
could be handed down to us in the fossil state except in those cases where
the cell-walls were either silicified or impregnated or coated with lime.

As far back as the Laurentian period, beds of graphite occur which
must undoubtedly have been the result of the decomposition of vegetable
matter, but all traces of the structure of the organisms from which it
has been derived are lost. The structures from the Russian coal-fields
described by Reinsch as the remains of algae allied to the Scytonemaceae,
are either the spores of Vascular Cryptogams, or, in many cases, are
inorganic crystallisations. Even the very earliest argillaceous deposits,
whether from fresh or from salt water, display long rounded trailing
impressions, which are believed by some writers to be the remains of
algae ; but it is exceedingly difficult to distinguish between these and

304

the trails of aquatic animals, or even ripple-marks. Carruthers is disposed
to regard the structure which he has called Nematophycus, from the
Lower Erian or Upper Silurian beds of Canada, as the earliest algoid
remains or impressions which have come down to us. The true nature
of the tracings in the still earlier Laurentian rocks known as Eozoon
canadense is still a subject of controversy with palaeontologists and
petrologists.

Coming down to more recent periods, the organisms described as
Chondrites and Confervites, found in the Cretaceous beds, were possibly
algae allied to the Confervaceae, and are thought by some to have had
a large effect in the precipitation of chalk from sea water, from the great
quantity of carbonic acid which they removed. From nodules in the
Pleistocene of Canada, Dawson obtains remains which he places under
genera allied to Ulva or Fucus, and possibly also to Laminaria. Various
other remains, sometimes of gigantic size, found in strata extending
over a very wide geological range, are referred by Saporta and others to
algae allied to the Laminariaceae and Fucaceae ; but the evidence is
generally too imperfect to justify a settled conclusion on the subject.

Of the calcareous remains of algae which have come down to us, the
most remarkable are those described by Munier-Chalmas, including
more than fifty genera, which he refers to the Siphonocladaceae, mostly
found in the Triassic, Jurassic, Cretaceous, and Tertiary strata. The
calcareous skeleton contains hollow chambers and canals where the rays
and the organs of reproduction were seated in life, rendering them very
. liable to be mistaken for the remains of Foraminifera, under which
class of animals many of them have been placed by palaeontologists.
Among these is the genus Ovulites from the Eocene.

LITERATURE.

Balfour— Introduction to Palaeontological Botany, 1872.

Carruthers - (Nematophycus) Monthly Microscopical Journal, 1872, p. 208.

Munier-Chalmas — Comptes Rendus, 1877, P- 814; Bull. Soc. Geol. France, 1881,

p. 661.

Saporta — Les organismes problematiques des anciennes mers, 1884.
Reinsch — Micro-paleeophy tologia, 1 884.
Nathorst— Nouvelles observations sur des traces d'animaux et autres phenomenes

d'origine purement mecanique decrits comme Algues fossiles, 1886.
Delgado— Etudes sur les Bilobites, 1886, 1888.
Dawson— Geological History of Plants, 1888.
(See also under Fossil Vascular Cryptogams.)

FIFTH SUBDIVISION.
FUNGI.

UNTIL recent years Fungi were looked upon as a great group embracing
all Thallophytes which do not vegetate by means of intrinsic chloro-
phyll. With the advance of research and the widening of knowledge, a
new classification of Thallophytes . was established, mainly by Sachs,
which was based on the characters of the sexual organs, and under it
groups were constituted composed of Algae and Fungi alike, in recogni-
tion of the principle that a mere physiological attribute, such as the
presence or the absence of chlorophyll, should be no bar to the bringing
together of organisms associated with each other by morphological
characters. With the analogy before their eyes of the relationship of
flowering parasites devoid of chlorophyll with green Flowering Plants,
morphologists readily accepted the proposed grouping, and until a
few years ago it was generally adopted. It then became apparent
that this step, though in the right direction, exceeded due bounds ;
and, with the first publication by de Bary of the classification of Fungi
used in this treatise, a new movement, which cannot, however, be justly
called a reaction, took place. This classification recognises a main
group of Fungi branching off from the Algae (Chlorophyceae), and defi-
nitely marked by morphological relationship. This main group differs
from the old group of Fungi not only in its internal disposition, but in
the exclusion from it of Mycetozoa and Bacteria, though it resembles
the old group in its latter days in the inclusion of lichen-forming fungi.
As clearly characterising and delimiting the group, the words of de Bary
(' Lectures on Bacteria,' p. 2) may here be quoted :—

' The term Fungi denotes a group of lower plant-forms, distinguished
by definite characteristics of structure and development, and recognised
at once when we see a mushroom or a mould. The members of this
group are all, as a matter of fact, devoid of chlorophyll, but they might
contain chlorophyll and yet belong to this group, just as a bird may
have no apparatus for flight, and yet be allowed to be a bird. To these
Fungi, as defined by natural history, and not by physiological characters

x

3o6

FUNGI

only, Bacteria are as little related in structure and development as bats
are to birds ; the relationship is even less, because there are a few,
though only a few, true Bacteria which contain chlorophyll and decom-
pose carbon dioxide, and which are therefore not Fungi in the physio-
logical sense.'

HlSTOLOGICAL CHARACTERISTICS.

The thallns of fungi consists of one or more cylindrical hyphce
branching in monopodial fashion, rarely dichotomously, and increasing
by apical growth. In numerous instances the hypha remains, for a
period at least, unsegmented, but most frequently transverse septa are
formed either in the apical cell or in segment-cells of the first order,
The thallus of the simple filamentous fungi consists of one hypha with
its ramifications. The so-called compound thallus of larger fungi is
formed of hyphae of which the branches meet and remain in close
contact. While all fungi have the filamentous habit to begin with,

FIG. 266. — Clamp-connec-
tions : mycele of H\-
pochnu* centrifugiis Tul.
(X39o). (After de Bary.)

FIG. zf.-j. — Pseudo-parenchyme brea ng up at end
into separate hypha; : Xectria cinnabarina Fr.
(highly magnified). (After Reinke )

some remain so throughout their whole development, and others are
characterised by both habits in different periods of their life-history.
It should also be mentioned that the whole thallus of a fungus may be
reduced to a single globular cell. Clamp-connections take place, especi-
ally in the Basidiomycetes, between adjoining segment-cells of the same
hypha by means of a protuberance emitted from the one nearer the
growing-point. This protuberance issues immediately above the trans-
verse wall, and effects a junction with the cell beneath. By this means
open communication is maintained between the cells for a time, but it is

FUNGI

307

eventually closed by the formation of a transverse wall in the protube-
rance. Cross-links, loops, &c., are frequently formed between branches
of the same hypha, or between originally distinct hyphae, by the resorp-
tion of the membranes at the point of contact. The coherence of the
compound thallus is most commonly effected by the more or less dense
interweaving of the hyphae, and by the cementing of them together in
many cases by an intercellular substance. The union of the component
hyphse may proceed so far, and the conditions of pressure, &c., be so
favourable, that a tissue
is formed resembling the
parenchyme of higher
plants. Being thus diffe-
rent from it in mode of
formation, the tissue in
question is \&rcs\£&pseudo-
parenchyme.

The form of hypha
•described is not universal
among fungi. Sprouting,
as it is called, is cha-
racteristic of the thallus
•of the yeast-fungus Sac-
•charomyces, and it occurs
in certain stages of other
fungi, such as Mucor.
This process consists in
the production of ovoid
•or globular cells, by means
of excrescences which
remain connected by a
narrow base with the pa-
rent cell, and are eventu-
ally cut off at or before
maturity by a cross-parti-
tion. This process, on being repeated again and again undisturbed,
exhibits in the result the appearance of a copiously-branching hypha
formed of bead-like cells. This connection, however, is very easily
broken, and the usual appearance presented is that of small aggregates
of sprouting cells.

Cell-contents. — The cells of fungi are characterised rather by the
absence of certain cell-contents than by the presence of peculiar sub-
.stances. The absence of chlorophyll and of starch-grains is most note-

FIG. vf&.—Saccharoinyces cerevisicz Meyen. a, single cell
of beer- yeast ; b, c, stages of sprouting ; d, colony of sprout-
cells ; e, cell with four ascospores ; f, one with two ; g, group
of ascospores with one sprouting ; h, further development of
a similar group (Ji x 750, the others much more), (e — h
after Reess.)

3o8 FUNGI

worthy, and the physiological substitution for the latter of fatty matters
Glycogen is found in the asci of Uiscomycetes and Tuberacese, and in the
vegetative cells of these and other fungi. Crystalloids of albuminoid
substance occur in the sporophores of Mucorini. Nuclei are of frequent
occurrence in the cells of the reproductive system of many fungi, and in
the vegetative cells of the Saprolegniese and other groups, though abso-
lutely satisfactory evidence has not been produced with regard to their
common presence in the thallus of fungi, apart from the reproductive
system. Unsegmented hyphae resemble the Siphoneous Algas in their
multinucleate condition, though single cells of segmented hyphae also
sometimes contain several.

Cell-membrane. — The typical cell-membranes of fungi consist of a
substance differing from cellulose in its behaviour to the usual reagents,
which is therefore known by the special name of Fungus-cellulose. Richter
contends that this difference is more apparent than real, since he found
that after prolonged maceration in a 7-8 per cent, potash solution, mem-
branes exhibited the ordinary cellulose reaction which had refused the
reaction after treatment of the usual kind with boiling potash solution,
&c. De Bary, who originally gave the name of Fungus-cellulose to the
membranes of fungi, welcomes these observations as confirming the un-
doubted near affinity of such membranes to ordinary cellulose, but
points out that it merely proves that the membranes of the fungi
operated on by Richter are altered by maceration with potash in the
way described. ' Whether 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 pos-
sible' (* Comp. Morph.,' p. 13). It is specially noteworthy that the
membranes of certain filamentous fungi (Saprolegnieae, &c.) exhibit the
ordinary blue reaction with iodine.

The membranes of fungi undergo thickening and stratification, but
are rarely pitted. The capillitium-threads of Lycoperdon are pitted, for
example, and spiral and annular thickening occurs in the corresponding
structure in Batarrea. Membranes very frequently become coloured
with age, and undergo sclerosis ; while in contrast to that condition
other membranes often occur, which, though hard and horny in a dry
state, swell up enormously by absorption of water, and acquire a gela-
tinous consistency.

Calcium oxalate, though of common occurrence in various forms
in fungi, is of extreme rarity within their cells ; Russula adusta (Fr.) and
Mutinus caninus (Fr.) are the only recorded instances known to us.

FUNGI

309

DIFFERENTIATION OF THE THALLUS.

It is usually possible to draw a fairly sharp distinction between the
vegetative part of the thallus, the mycele, and that portion specialised
for the bearing of propagative bodies, the sporophore. In reduced
forms, however, such distinction will be seen to be arbitrary, since
propagative cells are formed in such cases from otherwise undifferen-
tiated hyphal cells. The mycele, which serves the same physiological
purposes as roots in point of the absorption of nutriment and of attach-
ment, occurs in a variety of forms. The simplest and the typical form
is a loose filamentous condition, spreading on or in the substratum, and
.sometimes provided with

special branches termed d B

haustoria, which pene-
trate cells of living
plants and act as special
organs of nutrition and
of attachment. Such are
the haustoria of Perono-
sporeae and Erysipheae,
&c. A denser condition
of mycele is represented
by a membranous state
to be found in forms
vegetating on the sur-
face of fluids and in fungi
which attack wood, such

dry-rOt (MeruliuS FlG. 269. — Intercellular mycelial hypha: (;«), with haustoria
r ^ anH vprv penetrating into cells (z), A, tfCystopus ccindidns Lev. ; B, of
r.; ana Very Peronospora calotheca de By. ( x 390). (After de Bary.)

many others. Strands

of mycele are formed frequently in the Gasteromycetes and other
fungi possessing compound sporophores. The strand-mycele of Aga-
ricus melleus (L.), formerly known as Rhizomorpha, possesses a
highly-developed structure, in which a cortical and a medullary region
may be distinguished. Most compact of all forms of mycele are those
known as sderotes — densely compacted tuberous bodies. These con-
sist of a central medullary tissue composed of very compact uniform
hyphae, sometimes pseudo-parenchymatous, enclosed by one or more
layers of cortical cells with sclerosed walls. They are resting states of
mycele, and act as stores of reserve material. With sclerotes may be
classed such sclerotioid bodies as Pachyma and Mylitta, the develop-

3io

FUNGI

ment of which is quite unknown. Sclerotes were formerly classed to-
gether under the generic name of Sclerotium before it was recognised
that such bodies are mere growth forms, or rather resting forms, of
myceles of different fungi. Such a strand-mycele as that of Agaricus
melleus (L.), formerly considered an independent fungus (Rhizomorpha),
noticed above, has been aptly called a sclerote with a growing-point.
B. Frank (Ber. Deutsch. Bot. Gesellsch., 1885) has described masses
of fungal hyphae having a dense sclerotioid structure investing the roots
of trees (Cupuliferae, Salicaceae, Coniferse) and intimately associated with
the superficial cells of the root. To these bodies, termed mycorhiza, a
symbiotic relationship with the trees in question is attributed, viz., the

FIG. 270. — Agaricus mellens L. Longitudinal section through apex of rhizomorph-strand
(x 250). (After de Bary.)

absorbing function of root-hairs, the formation of which mycorhiza
suppresses.

The sporophores of fungi are either simple or compound. They
arise from the mycele, and produce the spores or definite organs
of propagation. Simple sporophores are commonly erect branches
of the mycele which either remain unbranched or branch again.
The spores are borne at the extremities, and with the production of
these bodies the growth of the sporophore either ceases altogether, or
it may be renewed with farther production of spores. The modes of
branching and the forms of sporophore are characteristic of species of
fungi. Comoound sporophores are structures often of considerable size, of

FUNGI 311

varying external appearance, and of a certain degree of differentiation of
tissue. This differentiation is exhibited in the formation of layers, some-
times pseudo-parenchymatous, adapted for special functions. They are

FIG. 271. — Section through sclerote of Sclerotima Sclerotioniin Lib., showing its cortical
medullary tissue (x 375). (After de Bary.)

commonly characterised by the bearing of spores, or special spore-
mother-cells, on definite regions and in more or less definite arrange-
ment. They form, as a rule, that portion of the whole organism which

FIG. 272.— Simple sporophores of Phytophthora infcstans de By. a, formation of first
spores (zoosporanges) at ends of branches ; b, two ripe spores on each branch and a third
being formed (x about 200). (After de Bary.)

is popularly termed a fungus, such as the stalk and cap of mushrooms,
the peridium of puff-balls, and the like. The structure of these is, as
has been said, very diverse, and it will be found described in more or

3I2

FUNGI

less detail under the different groups of fungi. It may be well to note
that transition-forms occur between the simple and compound types of

FIG. 273. — Agaricns dryophilns Bull. «, compound sporophore, longitudinal section showing
the course of the hyphae, a very young complete specimen 1*3 mm. in height, first beginnings
of pileus ; b, older specimen with pileus 2*5 mm. in breadth : /, piece of a lamella (slightly
magnified). (After de Bary.)

sporophore : for example, Penicillium, though commonly simple, some-
times produces tufts of sporophores formerly supposed to belong to a
different fungus under the generic name of Coremium.

SPORES.

The prevailing mode of spore-formation is by acrogenous adjunction.
The terminal portion of the mother-cell or a special protuberance formed
on it is cut off by a transverse wall, and this daughter-cell then drops off
as a spore. The basidiospores of Basidiomycetes may be taken as an
example. Finely pointed processes are formed on the summit of the
basid, and these swell into ball-like form at the apex. The globular
body is then abjointed and set free as a spore. Series or chains of
spores are successively formed in like fashion in Cystopus, Penicillium,
Uredinese, £c. Spores are also endogenously formed within mother-
cells — sporanges — and these are of two kinds, motile and non-motile.
Examples of non-motile spores thus formed are to be found in Mucor,
and in the ascospores of Ascomycetes. Such spores are either set free by
the disappearance of the sporangial wall or by internal causes effecting
their ejection. Motile spores or zoospores (swarm-spores) possess the
power of moving freely in water by means of fine whip-lashes or cilia,
and examples of these are to be found in the Saprolegniese and Perono-
sporeae, the groups presumably most nearly related to Algse. That the
phenomenon of the production of swarm-spores is one nearly akin to that

Frc. "274. — Pnccinia graminis
Pers. t, teleutospores ; u, ureclo-
spores ( x 390). (After Sachs.)

FIG. 275. in, mycelial branch of Cystopus Portulaceez
Lev. producing two basids abjointing spores, in series ;
b, sporophore of Enrotium het bar iorit HI Lk. with
sterigmata ; 5 and t, portions showing sterigmata,
/, p, with their spores, n being the youngest (a. x 390,
the rest x 300). (After de Bar}*.)

FIG. 276. — Pcziza (JPyroncina) conjJuens^e.rs. a, small portion of hymenium : J>, paraphyse attached
to, not originating in, hyphal branches from which the three asci spring; 111, young asci ; r u>,
successive stages, according to letters, in the development of ascospores within asci (x 390). (After
de Bary.)

FUNGI

of simple germination by the emission of a germ-tube is manifest. The
example of Phytophthora infestans (de By.) illustrates this. The acro-

genously-formed zoosporange pro-
duces zoospores in pure water

& MffnB /. e> containing free oxygen in fair

1 _ ^ amount. In nutrient solutions, on
the other hand, no zoospores are
formed, and the potential zoospo-
range simply emits germ-tubes.
Germination of spores, however,
takes place characteristically in

spores ; c. free zoospores \d -spores come to rest fungi by the emission of germ-
and germinating ( x 390). (After de Bary.) .

tubes under 'conditions of tempe-
rature, moisture, and the like presently to be discussed. Germination
by the formation of sprout-cells, however, occurs in a number of forms.

SEXUAL REPRODUCTION.

This subject is incidentally so fully discussed under the different
groups, that nothing need be said here beyond calling attention to the
fact that it falls under the same types as in Algae. Such a form as
Polyphagus may, however, be' mentioned since it exhibits a type apart
from ordinary isogamous or oogamous reproduction.

CONDITIONS OF GERMINATION.

Spores may be divided into
two categories with reference
S, to their power of germination,
viz. those, by far the majority,
which are capable of germina-
tion from the time of maturity,
and those which must undergo
a period of rest. Of the first
kind a considerable number,
generally speaking thin-walled
watery spores, sporids, or zoo-
spores, do not retain this power
for more than a period measured

FIG. 278. — Ascospores of Ht-fcella esculent a. Pens, i v ji T>U A'

Stages of germination in order of letters (x 39o). by hOUrS Or QayS. 1 he COnCil-

tions under which they are kept

are, as will be expected, of importance in this respect. Many spores
retain the power of germination for a long period if kept in an air-dry

FUNGI 315

state. This time extends in numerous instances to one or two years, and,
in the case of spores of Ustilagineae especially, to longer periods. The
spores of Tilletia caries (Tul.) germinated after eight and a half years, and
those of other species after shorter intervals varying from seven an'd a half
downwards. Resting-spores, or those of the second category, generally un-
dergo more or less definite periods of rest corresponding to periods of vege-
tation. While germination cannot be procured before the lapse of this
time, they frequently exhibit inability to survive the occasion presumed
to be favourable. Such are hibernating spores like the teleutospores of
Uredineae, and the oosperms of Peronosporese. Resting-cells belonging
to saprophytes again, e.g. the zygosperms of Mucorini, while they undergo
a necessary period of rest of varying duration, yet display no partiality
for seasons of the year, and this also is intelligible in view of their mode
of life.

The power of resistance of spores to external agencies operating
against their vitality is in many instances very great. The spores and
zygosperms of several Mucorini withstand mechanical injury and re-
pair slight wounds while preserving the power of germination. Short-
lived spores and those of aquatic fungi do not bear desiccation : but
a great number of spores retain the power of germinating, as has been
stated, for considerable periods in an air-dry state. Spores adapted for
hibernation in temperate climates, and, it may be assumed, long-lived
spores, withstand very low degrees of temperature, ranging below zero
C. ; while such long-lived spores, on the other hand, are very sensitive
to high temperatures. The capacity for germination after exposure to
high temperatures is maintained or not within certain degrees, according
to the dryness or humidity of the environment. Thus it has been
shown that while no spores are known to withstand a temperature of
100° C. in water or watery vapour, and many perish under these circum-
stances at much lower temperatures, the same spores can endure a
considerably higher temperature in a dry state. Dry spores of some
fungi have been found to withstand temperatures up to 120° C.
and beyond, but it is probable that 130° C. marks the death-point of
all. Others, again, perish at degrees considerably below 100° C. It
must, of course, be borne in mind that the duration of the exposure is
an important factor in such experiments, and that spores which support
a high temperature for a few minutes or an hour are killed by longer
exposure. It is probable that much individual variation exists in
regard to this matter and to the duration of life under ordinary circum-
stances, and that in this lies the explanation of conflicting results ob-
tained by different experimenters.

There is not much known as to the maximum, minimum, and

3i6 FUNGI

•optimum temperatures at which the actual germination of spores takes
place. According to Wiesner. the minimum for the spores of Penicil-
lium glaucum (Lk.) is from 1-5° C. to 2°, the optimum about 22° C, and
the maximum 40° C. to 43°. This may be taken as fairly illustrative of
other fungi in temperate countries in the open. Those which germinate,
like many Mucorini and fungi inhabiting excrement, in the digestive
tract of warm-blooded animals, have a much higher minimum, and an
optimum agreeing with the body temperature. A supply of water and
of oxygen must accompany the favourable temperature in all cases, and
of nutrient substances in some. Speaking generally, parasites germinate
freely in pure water or vapour, and saprophytes in nutrient substances,
but the spores of many fungi germinate in both.

CONDITIONS OF VEGETATION.

Under this head it will be necessary to consider little else than
the nutritive adaptation of fungi, since they resemble other plants in
the general conditions of vegetation, in their dependence on tempe-
rature, light, &c. The optimum temperature varies, as might be ex-
pected, in the cases of fungi which flourish at different seasons of the
year, and in different climates. The optimum temperature for the
growth of mycele in Penicillium glaucum is about 26° C., while that
of spore-formation is the same as that of germination, about 22° C.
These figures may be taken as fairly illustrative.

Luminosity 1 is exhibited by a considerable number of fungi — Agari-
cus olearius (DC.) and the rhizomorph form of A. melleus, Polyporus
annosus (Fr.), and P. sulphureus (Fr.) .(Europe), Agaricus igneus (Tul.)
(Amboyna), A. noctilucens (Lev.) (Manilla), A. Gardneri (Berk.) (Brazil),
A. lampas (Berk.) (Australia), A. Emerici (Berk.) (Andaman Islands), a
species of Didymium (Jamaica), and probably by a number of other forms,
the evidence as to which is doubtful. It is a phenomenon dependent upon
the life of the organism, and the progress in it of destructive metabolism.

As regards nutrition, the absence of chlorophyll and the consequent
inability to decompose carbon dioxide drive fungi to seek for organic
carbon-compounds. In taking up food, fungi cause chemical changes
in the organic bodies which furnish the food, e.g. fermentation. The
well-known ferment-fungi need only be mentioned. It is in the highest
degree probable that the solvents secreted by such fungi as penetrate
dense woody and other structures are ferments. All fungi may be

1 Vines, Lectures on the Physiology of Plants, p. 317 ; see also Phillips, Proc.
Woolhope Chil>, 1888.

FUNGI 317

divided primarily into such as feed on the decaying bodies of plants
and animals and dead organic substances —saprophytes — and those which
attack living bodies— ^arasi/es. Between the two extremes of strict
saprophytes and strict parasites there are intermediate forms. Some
saprophytes, which ordinarily live throughout their course of develop-
ment as such, have the power of living as parasites either wholly or
during a part of their course of development. Such are called faculta-
tive parasites. Similarly some parasites which ordinarily live as such
have the power of passing at all events a part of their lives as sapro-
phytes. Such are facultative saprophytes. The lichen-forming fungi
which live socially with algae may be placed in another category. Most
fungi are saprophytes, and it is obvious, from the fact that so many are
confined to specific substrata, that there is much variation in the nutri-
tive adaptations of such forms. These adaptations are, however, more
clearly marked in the case of the smaller number which lead parasitic
lives. Some are confined to single species of host-plants ; many range
over allied species, some of them attacking plants outside the group
mostly affected, or exempting from attack certain species within the
group. Others, again, may be said to be omnivorous parasites, attack-
ing plants or animals of diverse groups. With regard to the predisposi-
tion of the host to the attack of the parasite, it is impossible for the
most part to say exactly wherein it lies. Reference may be made to the
case of species of Pythium which as facultative parasites attack Phanero-
gams, £c. The amount of water present in the host determines there
the degree of predisposition to attack. While a sickly condition may
constitute a predisposing cause to the attack of a parasite in some
cases, it is by no means so in the majority of instances. It has been
asserted that certain cultivated plants, such as cereals and the potato-
plant, have by cultivation acquired an 'inherent tendency ' to certain
parasitic diseases, whereas it is obvious that the growing together
of vast numbers of these plants furnishes opportunity for the spread of
diseases which, in the absence of other evidence, may be taken to
account for extensive outbreaks. Parasites commonly attack their hosts
by the penetration of the membranes of the uninjured host, though
cases are numerous where the entry is made by means of the stomates,
or of wounded surfaces only. Most are endophytes, but a small number
— e.g. Erysiphe— are epiphytes, which send haustorial branches into the
body of the host. The result of attack is either the destruction of the
host, or the production of deformities by anomalous processes of growth
in the parts affected.

FUNGI

LICHEN-FORMING FUNGI.

These are strictly parasitic fungi which, without the aid of algal
hosts, do not develop beyond the earliest stage of germination. Their
nutritive inter-relations with their hosts, however, mark them off from
other parasites. The hyphae of the lichen-fungus embrace the algal
cells, and the two elements together compose a thallus of definite form.
The algal cells form by means of their chlorophyll-contents organic
•carbon-compounds by which the fungal cells benefit ; but here the

resemblance to true parasitism
ceases. The host exhibits no
sign of exhaustion, since a reci-
procal accommodation exists be-
tween the two elements. The
rhizoid filaments of the fungus
draw from the substratum mineral
substances, the raw material of
food. The hyphal cells are fed
by the exosmose of starch and
the like from the algal cells, and
the inference is justifiable that
the algal cells receive in exchange
by endosmose the waste products
of the fungal protoplasm. There
thus exists a lasting consortism or
symbiosis between the elements,
and the result is a thallus which
may be treated from the point
of view of the systematist as an
autonomous organism. It must
never be forgotten, however, that
it is fundamentally two organisms, one of which, the fungal, cannot live
without the other, while the latter can and does exist separately and
independently in nature. It is a question not definitely decided whether
certain algal forms thus living in consortism can or cannot live separately,
and it is also doubtful whether the fungal portion of such lichens as live
on the bark of trees or substrata rich in humus, does not live partially
as a saprophyte. Evidence certainly points in this direction. The sym-
biotic relations existing in lichens are comparable with those described
by Geddes, Brandt, and others, as in operation in Radiolarians and
other animals, the ' yellow-cells ' of which are actively vegetating algas.

FIG. 279. — Algal cells of Lichens. A, spore of
Physciaparietina Nyl. germinating on Protococ-
cus 'z'iridis Ag. B, Synalissa symphorea Nyl.
with Glccocapsa. C, Cladonia /ztrcata. Hoffm.
with Protococcus. D, Stereocaulon rainuiosum
Ach. with Scytonema. (A, B, and C, x 950,
D x 650.) (After Bornet.)

FUNGI

319

By far the greater number of lichen-forming fungi are Discomycetes
or Pyrenomycetes. A few small tropical genera, Cora (Fr.), Rhipidonema
'(Mattir.), Dictyonema (Mont), and Laudatea (Johow.), are Basidiomyce-
tous, and two other tropical forms, Emericella (Berk.) and Trichocoma
(Jungh.), have recently been declared by Massee(Phil. Trans. Roy. Soc.
Lond., vol. 178, p. 305) to be Gasteromycetous
Lichens. The two last-named cases are by no (
means satisfactorily established, and much more ?
and better evidence must be forthcoming before

FIG. 280. — Coccocarpia inolybdia Pers. Transverse section of
thallus. or, upper, and nr, under cortical layer. ;«, so-called
medulla ; g, algal cells ; r, rhizoids (x 6_o). (After Bornet.)

they can be adopted as lichen-forming fungi.
Propagation is effected by the spores of the fun-
gal thallus, and an adaptation exists in certain
lichens examined by Stahl for the supply of algae
to the new lichen. Algal cells, the offspring of
the thallus algae, which have been carried up into the hymenium, are cast
out along with the spores, so that, both falling in the same neighbourhood,
the germ-tubes of the spores find suitable hosts at once. This primary
synthesis, however, probably takes place comparatively rarely in lichens as
a whole. Propagation is very abundant by means of soredes or brood -buds

FIG. 281. — Ephebe pubescens
Fr. Branch of thallus with
two young lateral branches
(*) I £"> algal cells ; h, hypha;
(x 500). (After Luerssen.)

320

FUNGI

consisting of one or more algal cells surrounded by hyphce which separate
from the parent-thallus. As a rule one species of alga furnishes all the
algal cells of a lichen ; more rarely two, and then one prevails in abundance

FIG. •i&z. — Usnea barbata Fr. Development of soredes. a, group of eight algal cells attached to
hypha ; b, similar group with branching hypha ; c, sorede with algal cell in optical section ; d, sorede
with algal cells divided ; e,f, germinating soredes ( x 500—700). (After Schwendener.)

over the other. The same species of alga, however, may be found in
consortism with different species of fungus, and taking part in the com-
position, therefore, of differently formed thalli — different lichens in short.

FIG. 283. — Cctraria islandica, Ach., a fruticose lichen (natural size).

Stahl experimentally proved this in his successful attempts at lichen
synthesis. The algae which furnish the hosts belong to different groups,
and both unicellular and filamentous forms occur.

The thallus of lichens is of two sorts, the heteromerous and the

FUNGI 321

homoiomerous. The heteromerous thallus mainly consists of the fungus
body of the lichen differentiated into a cortical layer and a medullary
layer, the algae occurring either as a definite layer where the cortical
and the medullary hyphae join, or they are scattered throughout the
medulla, or form a dense mass in it. Such thalli exhibit considerable
variety in forms of growth, and are &£&.£.& foliaceous,fruticose, crustaceous^

FIG. 284. — Roccella tinctoria DC. A filamentous lichen. Small plant (natural size).

&c., in descriptive works. The homoiomerous thallus consists of algal
cells and hyphae more or less equally distributed and alike in bulk.
Collema, referred to below, is a gelatinous lichen, exemplifying this
structure. Though the fungus does not actually prevail in bulk, it
modifies the form of the thallus.

Until comparatively recent times, lichens were considered ' to be

Y

322 FUNGI

independent organisms, the algal portion, the so-called 'gonidia,' being
regarded as only specially developed cells arising from the colourless cells
of the thallus. In 1868 Schwendener first accurately determined their
dual nature, though de Bary had two years before indicated the possibility
of this state of things in the case of the Collemaceae, &c. The dis-
covery so far, though sufficiently convincing, was based on anatomical
considerations only, but the matter was finally proved, as well as a thing
can be proved, by the experiments of Bornet, Treub, Reess, and Stahl.
Reess succeeded in producing the thallus of Collema by synthesis, and
Stahl went a step farther, and effected the formation of no less than
three species of lichen. His observations on the relations of the algal
and fungal elements of the lichen-thallus crowned the work of demon-
stration of its dual nature. Many systematic lichenologists who have
been unable to shake off the traditions of their study still cling to the
old view of the independent nature of lichens. It is hardly necessary
to point out that the judgment of morphologists on such matters is the
one to be trusted, especially as the matter has once and for all passed
beyond the state of trust in authoritative opinion into the perfect state
of complete proof.

LITERATURE (BOOKS OF GENERAL REFERENCE).

DC Bar}'— Vergleichende Morphologic u. Biologic der Pilze, Mycetozoen u. Bacterien
(Leipzig, 1884). [Translation by Garnseyand Balfour, Oxford, Clarendon Press,
1887, referred to in text as de Bary, Comp. Morph., &c.]

(In- the above book a complete guide to the detailed morphological literature
will be found.)

Systematic.

Saccardo — Sylloge Fungorum (1882, in progress). This work is intended to include
all known Fungi.

The student should also consult the numerous works of Fries, dealing
chiefly with Basidiomycetes ; Corda's Icones Fungorum (Prag, 1837-54) ; and
for British Fungi, Berkeley's Outlines of British Fungology (1860) ; Cooke's
Handbook of British Fungi (1871); the same author's Illustrations of British
Fungi (1881, in progress) ; Stevenson's Hymenomycetes Britannici (Edinburgh,
1886) ; and Phillips' Handbook of British Discomycetes (London, 1887).

Diseases of Plants caused by Fungi.
Frank — Krankheiten der Pflanzen (Breslau, 1880-81).
Sorauer — Handbuch der Pflanzenkrankheiten (Berlin, 1886).
Smith, W. G. — Diseases of Field and Garden Crops (London, 1884).

Literature of Lichen-thalhis.

This literature is too vast to be quoted here in detail, but the reader is re-
ferred to the following essential papers.

Bornet — Recherches sur les gonidies d. Lichens (Ann. Sc. Nat., ser. 5, xvii. and xix.).
Johow — Ueber Westind. Hymenolichenen (Sitzber. Berl. Acacl., 1884).

OOMYCETES

323

JReess — Ueber d. Entstehung d. Flechte Collema glaucescens (Monber. Berl. Acad.,

1871).
Heess — Ueber d. Natur d. Flechten (Samml. wiss. Vortrage von Virchow u. v.

Holtzendorff, 1879).

Schwendener— Die Algentypen d. Flechtengonidien (Basel, 1869).
Schwendener — Erorterungen z. Gonidienfrage (Flora, 1872).
Schwendener — Die Flechten als Parasiten d. Algen (Verb. d. Basel, naturf. Ges.,

1873).

Stahl — Beitr. z. Entwickel. d. Flechten, ii. (Leipzig, 1877).
Treub— Lichenencultur (Bot. Zeit., 1873).
Treub — Onderzoek. over d. Natuur d. Lichenen (Diss.) (Leiden, 1873).

SPECIAL literature is quoted tinder each groiip.

GROUP L— PHYCOMYCETES.

Class XVIII.— Oomycetes.

ORDER i. — PERONOSPORE.E.

The thallus of the Peronosporeae consists of irregularly and copiously
branched hyphae inhabiting for the most part the living, and especially
the chlorophyll-bearing, tissues of terrestrial flowering plants of different
natural orders. The
mode of life in this case
is parasitic, and the
hyphae usually follow
the intercellular spaces,
and in many cases send
short processes termed
haustoria into the ad-
joining cells. These
haustoria are variously
formed according to the
species. They are gene-
rally branched in Pero-
nospora (Corda) and glo-
bular in Cystopus (Lev.).
The hyphse of other
species (Phytophthora,
de By.) traverse the cells
of the host- plant. Trans-

FIG. 285. — Intercellular mycelial hyphae (;«), with haustoria
penetrating into cells (z), A , of Cystopus candidrts LeV. ; B, of
Peronospora calothcca de By. ( x 390). (After de Bary.)

verse walls do not commonly appear in the hyphae until the period of the
formation of reproductive organs. The effect of this parasitic mode

324

FUNGI

of life on the host is extensive destruction of the tissues, usually ending
in death. Hypertrophy is produced in other cases, especially at the
time of the formation of oosperms, leading to swellings and distortions
of the parts affected.

Of the species of Pythium (Pringsh.) transferred to this order by
de Bary (Bot Zeit, 1881) from the Saprolegnieae, some are saprophytes
inhabiting the dead bodies of both plants and animals, while others
are both parasites and saprophytes.

The oogones are globular cells with either a smooth or a granulated
wall of some thickness, situated, as a rule, terminally, or more rarely
interstitially. Soon after separation by a transverse wall from the hypha
which bears it, the protoplasm of the oogone, which is rich in drops

FIG. 286. — Fertilisation of Peronosporeae. 7. — VI., Pythium gracile Schenk. Successive stages accord-
ing to numbers ( x about 800). VII.,Peronospora arbores>cens de By. Oosphere is in vested with a
thick membrane, outside of which is the periplasm contracting to form outer coat of oosperm ( x 600).
(After de Bary.)

of fatty matter, begins to collect into a central mass containing the
drops and bounded by a hyaline layer. Outside this central body
(oosphere] there is left over a clear mass of protoplasm (periplasvi], which
fills up the space between it and the wall. While the oogone is thus
developing, the antherid arises, either from the pedicel-cell of the oogone
itself, or as the terminal cell of a neighbouring branch. It has commonly
the form of an irregularly bent tube with an unthickened cell-wall, and
at first ordinarily granular protoplasm. It applies itself closely to the
wall of the oogone, and sends through it a delicate straight impregnating
tube, which penetrates to the surface of the oosphere. The protoplasm
of the antherid also undergoes about this period a differentiation into
two masses ; one, threadlike but irregular, and occupying the middle..

OOMYCETES 325

contains the more granular particles, and is termed the gonoplasm, while
the other (periplasvi) surrounds it. The gonoplasm enters the oosphere
through the impregnating tube of the antherid, and thus accomplishes
the act of impregnation. Sometimes two, rarely more, antherids arise
and apply themselves to the oogone, and this varies both with species
and individuals. After impregnation the oosperm assumes a cellulose
membrane, and gradually ripens. The fatty contents collect into one
body occupying the middle, and the membrane becomes thicker and
differentiated into two cellulose layers, the extine and the intine. The
periplasm develops into a brown, often granulated and warty membrane,
the extine, enclosing the oosperm, while the original wall of the oogone
generally breaks up, but may in some cases persist.

The oosperms germinate in water after a period of rest generally
lasting throughout the winter ; and this takes place either by the emission
of a germ-tube which gives rise directly to a new thallus like the parent
one, or the protoplasm divides into a number ofzoospores, which, extruded
together within a globular sac and escaping from it, swim for a short
time, and, after settling down, push out each a germ-tube which pro-
duces a new thallus. In other species, again, both methods of germina-
tion occur, some of the oosperms directly emitting germ-tubes, while in
the others the production of zoospores intervenes. In certain species,
the oosperms of which produce a germ-tube directly, a short mycele
(promycele) is formed, which, after bearing a few conidiospores, dies, and
these conidiospores in turn propagate new thalli.

The non-sexual organs of propagation (conidiospores) are borne upon
.special branches of the thallus (sporophores) in a variety of ways cha-
racteristic of the genera and in a minor degree of the species. These
germinate either by means of a germ-tube directly produced, or the
contents break up into zoospores, which, after swarming, settling down,
and becoming invested with, a membrane, also produce germ-tubes.

The usual course of life is the production upon the thallus of vast
numbers of conidiospores, which propagate the species extensively
throughout spring and summer, followed in autumn by the bearing of
sexual organs, with which the generation terminates. De Bary points
out('Comp. Morph.,'&c., 1 884) that only in the instances above mentioned
of the production from the oosperm of a promycele bearing'a few coni-
diospores, can a distinct alternation of generations be recognised. There
is indeed merely the succession of one oosperm-bearing generation to
another, the propagating spores being only accessory products of the
thallus. In such cases as Pythium vexans (de By.) and Artotrogus
(Mont.), for example, there are no such organs of propagation at all, or
at least long-continued research, has failed to discover them. Other

326

FUNGI

species appear again to have lost the power of producing sexual organs,
and this is notably the case in Phytophthora infestans (de By.), the
potato-disease fungus, which succeeds in hibernating by means of a
perennial mycele. In such a case the species is entirely dependent
upon the propagating spores for distribution.

Cystopus (Lev.). — The thallus consists of hyphae inhabiting the
intercellular spaces of the tissue of flowering plants, and provided with
haustoria. The oosperms are resting-cells which ger-
minate in spring by means of the production of zoo-
spores in the usual way. The propagating zoospores
are borne in zoosporanges at the end of cylindrical or
club-shaped zoosporangiophores in vertical series. A
small broad swelling first appears at the apex, and
then a transverse wall cuts off the \ipper portion,
which rounds off and thus becomes the first and
oldest zoosporange of the series. Then another is
cut off in the same fashion, while the sporangio-
phore elongates. A series or chain is thus produced,
each zoosporange joined to its neighbour by a very
short and slender connecting stalk. The first cell
at the top of the series has a thicker wall than the
others, is yellowish in colour, and is, at least in the
vast majority of cases, incapable of germination. If
germination does take place, a germ-tube is said to
be produced, while all the other members of the series »
give rise to zoospores. These chains of zoosporanges
arise in dense masses stde by side below the epiderm
of the host, which is gradually ruptured, permitting
their escape, the thick wall of the top member of the
FIG. 287.—;«, myceiiai series serving as a shield in bursting the epiderm.
j^rtuiaceaiJv^pm- When the zoospores germinate, their germ-tubes enter
phoi-ef, A beSSngn?oo- the host by way of the stomates, by this means attain-
ing directly the intercellular spaces. The disease thus
set up in the host is not so active as in the case of
species of Peronospoja, and the parts affected do not perish so rapidly.
During the formation of oosperms in Cystopus candidus (Lev.), regions
of the host undergo acute hypertrophy. The commonest species of the
genus is C. candidus (' white rust '), which attacks a large number of
Cruciferae. Cabbages and the Shepherd's Purse (Capsella bursa-pas-
tqris) suffer conspicuously from ft, while the latter is often affected by
Peronospora parasitica (de By.)" in company with it; Other well-known
species are C. Portulaceas (Lev.) and £. cubicus (Lev.).

sporanges, *
.)

Bary.)

OOMYCETES 327

Peronospota (Corda). — The thallus and the sexual organs closely
resemble those of Cystopus. In both genera the passage of protoplasm
from the antherid into the oogone is not directly visible, and the
oogonial periplasm is more abundant than in the other genera. In
germinating, the oosperm produces a germ-tube, but the process of germi-
nation has not been observed in a number of species, and, as de Bary says
(Journ. Roy. Agric. Soc., 1876), it is quite possible that the species of
Peronospora which, like Cystopus, produce zoospores from their 'conidia'
(zoosporanges) present also the same phenomenon in connection with
the oosperms. The sporophores of Peronospora commonly issue from
the host-plant through the stomates, and are, for the jnost part, regu-
larly and copiously branched. At the fine points of the branches the
non-sexual propagating bodies are produced singly. These are rfi some
species conidiospores germinating by the emission of a germ-tube, and
in others zoosporanges producing zoospores. Conidiospores and zoo-
qporanges are borne in precisely similar fashion, and present the same
appearance up to the production of the germ-tube or zoospores, as the
case may be. The zoospores are formed within, and escape from the
original zoosporangial membrane and not from an extruded sac. Inter-
mediate between these forms are the plasmatoparous species (P. densa,
Rab., and P. pygmasa, Uhg.), in which the whole protoplasm escapes
from the spore in a mass through the opening of a papilla-like point in
the wall, and, at once becoming globular, secretes a cellulose membrane,
and subsequently germinates by the emission of a short thick germ-tube.
The germ-tubes both of zoospores and of conidiospores penetrate
directly the epiderm of the host and the cells underlying it, until an
intercellular space is reached. This genus contains a large number of
well-known parasites, such as P. viticola (de'By.) on the vine, P. nivea
(de By.) on . Umbelliferae, P. parasitica (de By.) on Cruciferse, P. Schlei-
deniana (Ung.) on onions ; P. Vicise (de By.), P. Trifoliorum (de By),
&c. Hypertrophy i$ frequently produced in the host at the time of
oosperm-formation, but not so acutely as by Cystopus. The oosperms
of several species are unknown, and of these P. Rumicis (Corda) and
P. Schachtii (Fiickel) hibernate by means of their perefinial mycele,
while P. Ficariae (Tul), the oosperms of which are known, passes the
winter in the same way.

Phytophthora (de By.). — This genus was founded for the reception
of P. infestans (de By.), which was formerly placed in Peronospora.
Industrious research has failed to discover thfc sexual organs and
oosperms of this species. Mr. Worthington Smith claims to have
found them, but the balance of evidence is distinctly against this.
The sexual organs of Phytophthora omnivora (de By.) have been

328

FUNGI

observed, however, and fertilisation takes place in the usual way. A
very small quantity of gonoplasm (not visibly differentiated) passes
over into the oosphere. The antherids and oogones arise together
in this species, and develop in close connection. The oosperms
form each a promycele, as described above. The sporangiophores of

each branch

FIG. 288. — Simple sporophores of Phytophthora infestans de By. a, formation of first
spores (zoosporanges) at ends of branches*: b, two ripe spores on each branch and a third
being formed (x about 200). (After de Bary.)

Phytoph|hora, which resemble those of Peronospora in general habit,
differ from them in the fact that each branch bears more than one pro-
pagating body — not in chains, like Cystopus, but at intervals on the
branch. In P. infestans a propagating cell is produced at the apex of
and as it ripens a papilla-like swelling arises beneath it ;
the branch grows on and turns
the cell aside. These propagat-
ing cells are usually zoosporanges,
but not unfrequently they are coni-
diospores, differing from them in
no other respect than the pro-
duction of a germ-tube directly
instead of zoospores. The zoo-
spores are formed within and
escape directly from the zoospo-
range itself, as in Peronospora.
Phytophthora infestans has a special economic interest, as the cause
of the well-known r&ta|D-disease. The "disease first appears, as a rule,
on the green leaves of the potato plant in July or August, the sporangio-
phores emerging through the stomates. Sporanges are formed, under
favourable conditions of temperature, moisture, &c., in a few hours, are

FIG. 289. — Zoosporanges of Phytophthora infestans
de By. a, division completed ; b, escape of zoo-
spores ; c, free zoospores ; d, spores come to rest
and germinating (x 390). (After de Bary.)

OOMYCETES 329

Avafted away, and, falling on other potato leaves, there produce zoospores,
or germ-tubes directly, in drops of water formed by dew or rain. The
germ-tubes penetrate the epiderm, setting up fresh growths of mycele in
new plants, and thus the disease is propagated. Countless numbers of
such propagating cells, each potentially the mother of a number of zoo-
spores, may thus be set free from a few diseased plants, and the spread
of infection and destruction of tissue in warm moist weather is almost
inconceivably rapid. The disease extends to all parts of the plant, in-
cluding the tubers, in which the mycele often remains in a resting con-
dition throughout the winter (as in certain species of Peronospora
mentioned above), and from which a fresh start is made in the following
year. The interest attaching to the subject is mainly economic, and an
extensive literature bearing upon it has grown up — by far the greater
part of it utterly worthless.

Pythium (Pringsh.). — Several species of this genus are saprophytes,
inhabiting the dead bodies of plants and animals, while others are true
parasites on fresh-water algae, on prothallia, and on flowering plants.
The thallus and sexual organs are of the type described, The oosperms
of P. proliferum (de By.), like those of Phytophthora omnivora, form a
promycele ; while of P. vexans (de By.) the oosperms only are known.
The formation of propagating spores occurs at the end of simple thallus-
hyphae. A terminal cell is cut off by a transverse wall, and usually becomes
a zoosporange. This body expands at the apex into a thin globular
sac, into which the whole of its protoplasm empties itself. There zoo-
spores are differentiated, and, bursting the sac, escape and germinate.
There is some variation according to species in the forms of the zoo-
sporanges ; sometimes they are round or oval and sometimes elongated.
They have not the definite arrangement which characterises the other
genera. P. intermedium (de By.) and P. de Baryanum (Hesse) some-
times form spores which emit a germ-tube instead of the usual zoospo-
ranges. P. gracile (Schenk), P. entophytum (Pringsh.), and P. Chloro-
cocci (Lohde) inhabit fresh-water algae, P. Equiseti (Sad.) and P.
circumdans (Lohde) attack prothallia, while P. de Baryanum infests
seedlings of different phanerogams and fern-prothallia. The last-named
is capable of attaining full development as a saprophyte on both dead
plants and animals. P. intermedium, also saprophytic, becomes a
parasite on fern-prothallia. It is worthy of note that these fungi are
parasitic only on seedlings, prothallia, &c., which contain abundance of
water ; and though P. de Baryanum causes local injury to grown plants,
'this power may be raised to one of destruction under water. Pythium
: vexans is found in diseased potato tubers.

330 FUNGI

FOSSIL FORM.

Peronosporites (W.G.S.). — This genus was founded by Mr. Worthing--
ton Smith for the reception of a fossil fungus Peronosporites antiquarius-
(W.G.S.), first detected by Mr. Carruthers in the axis of a Lepidodendron
from the coal measures. Mycele and bodies which may well be oogones
are visible in the preparations. The fungus is probably nearly related

to Pythium.

LITERATURE.

De Bary— Recherches sur le developpement de quelqnes Champignons parasites

(Ann. Sc. Nat., 4 ser., Tom. xx.). (Contains reference to older literature.)
De Bary— Zur Kenntnissder Peronosporeen (Beitr. zur Morph. u. Physiol. d. Pilze, ii.).
De Bary— Untersuch. liber die Peronosp. u. Saprolegn. (ibid., iv.).
De Bary — Research into the Nature of the Potato-fungus (Phytophthora infestans de

By.) (Journ. Roy. Agric. Soc., 1876, xii.).
De Bary— Zur Kenntniss der Peronosporeen (Bot. Zeit., 1881).
Cornu— Monogr. d. Saproleg. (Pythium) (Ann. Sc. Nat., 5 ser., Tom. xv.).
Hesse — Pythium de Baryanum, Halle, 1874.
Millardet — Le Mildiou (Paris, G. Masson, 1882 ; and Journ. d'Agric. pratique,

1 88 1, T. i., No. 6, and 1882, T. ii., No. 27).
Pringsheim — Die Saprolegnieen (Pythium) (Jahrb. wiss. Bot., i.).
Schroter — Peronospora obducens (Hedwigia, 1877, p. 129).
Schroter — Protomyces graminicola (ibid., 1879, p. 83).
\V. G. Smith — Resting-spores (so called) of Potato Disease (Gard. Chron., 1875, iv.,

N.S. ; and 1876, vi., N.S.).
W. G. Smith — Peronosporites antiquarius, W. G. S. (Gard. Chron., 1877). [See also

G. Murray, Academy, 17 Nov. 1877 and following numbers ; and Williamson,

Phil. Trans. Roy. Soc. Lond., 1881.]
A. Zalewski — Zur Kenntniss der Gattung Cystopus (Bot. Centralb., 1883, No. 33).

ORDER 2. — ANCYLISTE^:.

This order embraces a few genera which, so far as what is known of
them indicates, are related most nearly to Pythium. All the members
of the group are parasitic in fresh-water algae (Cladophora, Mougeotia,
Spirogyra, Mesocarpus, Closterium, &c.), and they are all farther charac-
terised by simplicity of structure. The thallus is represented by hyphae
at first undivided, which often extend from one end of the host-cell to
the other. Ancylistes Closterii (Pfitz.) displaces the chorophyll-plates of
its host, and ultimately causes the death of the cell. Lagenidium
(Schenk), found in filamentous algae, causes the separation of cell-contents
from cell-wall, and discolours the chlorophyll, which gathers together
into a mass.

The sexual organs are formed by the division into cells of the thallus-
hyphae by transverse walls. Of these cells, some swell and become
oogones, while others remain small and act as antherids (Myzocytium,.

OOMYCETES

33*

Schenk) ; or different individuals produce the oogones and the
antherids (Lagenidium, Ancylistes). A perforation having been made
in the oogonial wall, the whole of the protoplasm of the antherid empties
itself into the oogone (there being no periplasm), and the united mass
rounds itself off and becomes the oosperm. The germination of the
oosperm has not been observed.

Propagation takes place by means of zoospores (Lagenidium), and
to this end either the whole thallus-hypha becomes transformed into a
zoosporange, or it is divided into a series of such. Each zoosporange
sends out through the membrane of the host-cell to the surrounding
water a protuberance, through which the contents escape after the
fashion of Pythium, forming uniciliated zoospores, which ultimately
attack the fresh cells of other algae. In Ancylistes the only propagation
known is a process of extension of its hyphas from one host to another.

LITERATURE.

Cornu — Monogr. des Saprolegn. (loc. cit.).

Cornu— Note sur 1'oospore du Myzocytium proliferum, Schenk (Bull. Soc. Bot.

France, xvi., 1869, p. 222).

Pfitzer — Ein neuer Algen Parasit (Monatsber. Berl. Acad., 1872).
Schenk — Ueber das Vorkommen contractiler Zellen im Pflanzenreich (Wiirzburg, 1858).
Zopf — Ueber einen neuen parasitischen Phycomyceten, &c. (Lagenidium) (Bot. Zeit.,

1879, P- 350-

ORDER 3. — MONOBLEPHARIDE^E.

The single genus
Monoblepharis (Corn.),
like the preceding
group, is closely re-
lated to Peronosporeae
and especially to Py-
thium. The thallus-
hyphas bear both ter-
minal and interstitial
oogones, in which there
is no preliminary dif-
ferentiation of peri-
plasm, but the whole
protoplasm contracts
and forms the oo-,
sphere, while the apex
of the oogonial wall opens. The antherid (usually a cell adjoining an
oogone) produces several swarming antherozoids, which escape, one of

FIG. 290. — Monoblepharis sphcerica Cornu.
oogone, o, and antherid, a, antherozoid, s.
successive stages ( x 800). (After Cornu.)

Filament bearing an
The numbers indicate

332 FUNGI

them attaining and entering by the apical opening of the oogone, and
uniting with the oosphere. The resulting oosperm has not yet been
observed to germinate.

Propagation takes place by the formation of uniciliated zoospores in
-zoosporanges, from which they escape in the same way as those of

Phytophthora.

LITERATURE.

Cornu — Monogr. cles Saprolegn. (loc, cit.).

ORDER 4. — SAPROLEGNIEAE.

The Saprolegniese, as their name indicates, are saprophytes on the
•dead bodies of both plants and animals in water ; with at all events the
•exception of the Saprolegnia of the salmon disease, which is both sapro-
phyte and facultative parasite. The cause of the .predisposition to this
disease has not yet been exactly determined, as for example has been the
case with those species of Pythium which possess a similar mode of life.
Prof, de Bary points out with regard to them that susceptibility to disease
in the host is in relation to the amount of water present. The problem
in the case of the salmon disease has every appearance of being a more
.complex one. The Saprolegnieae bear in other respects much resem-
blance to the Peronosporeae, and especially to Pythium, which until
recently was included among the former. Pythium indeed presents
points of relationship with the types of Oomycetes in general ; and the
relationship is rendered the more striking by the union in some of its
species of both parasitic and saprophytic modes of life. The thallus-
hyphae of the Saprolegnieae are usually of relatively large size, springing
from slender rhizoids buried in the substratum.

The oogones arise, as in Peronosporeae, on branches of the thallus-
hyphae. In most cases, however, several oospheres are formed in each
oogone (sometimes as many as thirty or forty), and, no periplasm having
been differentiated, the whole of the oogonial protoplasm is included in
them. It happens in some cases that only one oosphere is formed,
but the number is variable according to species, and also partly according
to individuals. Pits arise, but by no means always, in the oogonial wall.

The antherids, which are commonly club-shaped, are produced on
slender branches of the thallus ; and each antherid is borne either on
the same hypha of the thallus as the oogone to which it is attached, or
on a hypha which bears no oogones. The remarkable point about
these antherids is their impotency, since no actual observation of the
transference of protoplasm from them to the oospheres has ever been
made, though they perforate the oogonial wall, and processes, like
impregnating tubes sent through, come in contact with the oospheres.
These processes grow from one oosphere to another, and may even

OOMYCETES

333

emerge again outside the oogonial wall, but they remain closed at all
points, and after a day or two perish. In the case of certain species, the
antherids never produce these pro-
cesses, or the oogones may be
without antherids. In other cases
antherids are never produced at all,
or only by way of rare exception.
In the meantime the oospheres ripen
into oosperms, while the antherids,
if present, perish. Pringsheim has
recently endeavoured to show that
impregnation takes place in certain
species by the transference into the
oospheres of minute portions of
antheridial protoplasm moving in
amoeboid fashion. De Bary points
out that, while Pringsheim has not
actually seen this, the sole evidence
trusted to is that of stained prepa-
rations, which appear to exhibit open
communication between antherid
and oosphere, &c. In any case the
observation does not affect those
cases where antherids are either want-
ing, or do not produce the penetrating
tubular processes.

The ripe oosperms thus parthe-
nogenetically produced germinate
after a period of rest varying from
a few days to several months. Ger-
mination takes place, as in the
Peronosporese, either by means of
a germ-tube, or zoospores are pro-
duced.

Propagation is effected by the
agency of zoospores produced in
special zoosporanges, and also excep-
tionally by means of certain resting-
cells formed by the- mycele after
transverse division of the hyphas
(Saprolegnia). These swell out into globular form, with thick mem-
branes and plentiful protoplasm, and germinate by the emission of a
germ-tube, or zoospores are formed in them ('resting sporanges' of

FIG. 5291. — A to C, Achlya racemosa Hildebr.
At the end of A is an empty zoosporange, j.
with empty zoospore membranes ; at a. b, and
c, are ocgones with antherids, a, in an early
stage, b and c as in £, oogone with two
oospheres and an antheridial tube applied
to one. C, ripe oosperm. Z>, £, Achlya.
polyandra Hildebr. D, oosperms germinat-

ing. E, germinating oosperm which has formed
a sporange with a head of spores. {A x 145.
B and C x 375, D and E x 225.) (After

334

FUNGI

Pringsheim). These resting cells or sporanges are formed only on

old myceles, and by no means regularly.

The zoosporanges vary in form with the
genus, and in a minor degree with the
species. The usual form is a large club-
shaped zoosporange containing a great
number of biciliated zoospores, which
escape from it through an opening at the
apex ; though in poorly developed indi-
viduals (and normally in Aphanomyces, de
By.), the zoosporange is more cylindrical,
and only one row of zoospores is formed.
In Saprolegnia (Nees ab Esenb.) the zoo-
spores are actively motile when they escape.
Their activity ceases for the most part
after a few minutes ; they settle down,
assume a thin cellulose-membrane, rest
for a short time, only to escape from this
membrane, and resume active movement
before final settling down and germina-
tion. The spores of individuals may on
the other hand omit the second period of
movement, and germinate directly on first
settling down. In Achlya (Nees ab Esenb.)
and Aphanomyces the spores escape from
the sporange without cilia and active
movement. They arrange themselves in
globular fashion outside the apex of the
sporange, assume each a thin cellulose-
membrane, within which they rest for a
few hours, and, escaping from it, swim
about, and, settling down, ultimately ger-
minate. In the sporanges of Dictyuchus
(Leitg.) the spores are each enclosed in

net-like cellulose walls, from which they escape, not by any special

orifice of the sporange, but by taking as it were the shortest cut through

the sporangial wall and empty spore -cases if they come in the way.

In Aplanes Braunii (de By.) the formation of propagating spores is

as a rule omitted. When produced they give rise to germ-tubes directly

without swarming.

The zoospores produced by oosperms behave, so far as is known

like those from the corresponding zoosporanges.

FIG. 292. — Zoosporanges of Achlya
N. ab E. A , with zoospores formed
but still enclosed. £, with zoo-
spores escaping. At a they are in-
vested with a cell-membrane, at c
they are free, empty membranes
at b (x about 300). (After de Bary.)

OOMYCETES 335

The modes of zoospore-formation in Phytophthora and Cystopus,
Pythium Achlya, and Aphanomyces, Dictyuchus, and lastly Saprolegnia,
express in an interesting way the relationships of these genera.

LITERATURE.

De Bary — Beitr. zur Kenntniss cler Achlya prolifera (Bot. Zeit., 1852).

De Bary — Einige neue Saprolegnieen (Pringsheim's Jahrb. wiss. Bot., ii.).

De Bary — Untersuch. liber die Peronosp. u. Saprolegn. (Beitr. zur Morph. u. Physiol.
der Pilze, iv.).

De Bary— Zu Pringsheim's Neue Beob. iiber d. Befruchtungsact cler Gattungen Achlya
und Saprolegnia (Bot. Zeit., 1883).

Cornu — Monograph, der Saprolegn. (Ann. Sc. Nat., 1872).

Hildebrandt — Mycolog. Beitrage, i. (Pringsheim's Jahrb. wiss. Bot., vi.).

Hartog— On the Formation and Liberation of Zoospores in the Saprolegnieae (Quart.
Journ. Micr. Sc., 1887).

Hartog — Recent Researches on Saprolegnieae (Annals of Botany, 1888).

Huxley and Murray — Salmon Disease (Reports of Inspector of Fisheries, 1882, 1883,
1884, 1885. See also Quart. Journ. Micr. Sc., 1882, and Journ. Bot., 1885).

Leitgeb — Neue Saprolegnieen (ibid., vii. ).

Lindstedt— Synopsis der Saprolegn., Berl., 1872.

Pringsheim — Entwickelungsgeschichte der Achlya prolifera (N. Acta Acad. Leop.-
Carol., xxiii., p. r).

Pringsheim— Beitr. zur Morph. u. Systematik d. Algen, ii. Die Saprolegn. (Jahrb.
wiss. Bot., i., ii., and ix.).

Pringsheim— Neue Beobacht. iiber d. Befruchtungsact von Achlya u. Saprolegnia
(Sitzber. Berl. Acad., 8 Juni, 1882). Nachtragliche Bemerk. zu dem Be-
fruchtungsact von Achlya (Pringsheim's Jahrb. wiss. Bot., xiv.).

Reinsch — Beobacht. iiber einige neue Saprolegn. (ibid., xi. ).

Thuret — Rech. sur les zoospores des Algues, 1851.

Ward — On Saprolegniere, and also on Pythium (Quart. Journ. Micr. Sc., 1883).
Contain histological details.

Class XIX.— Zygomycetes.

ORDER i. — MUCORINI. _

The Mucorini are for the most part terrestrial saprophytes, the re-
mainder being parasites on other Mucorini. The thallus consists of a
copiously branching hypha undivided up to the time of the production
of spores or sporanges, when transverse walls first appear. Sexual repro-
duction is effected by the formation of a zygosperm, while spores and pro-
pagating cells (like some of the resting-cells produced by the mycele of
Saprolegnia) are also borne, the former regularly and in characteristic
forms, the latter only in special cases and under certain conditions. The
production of a zygosperm is effected by the conjugation of two specially
differentiated cells, gametes, not to be distinguished from each other by
any mark or power of movement. The two cells thus contributing to

336

FUNGI

its formation either, by their simple fusion, themselves constitute the
zygosperm, or this body is the direct offspring (daughter-cell) of the
union. The spores are produced either in terminal sporanges or singly
at the apex of a sporophore, or again serially in like fashion to the last.
In a considerable number of cases the zygosperms are unknown, and it

FIG. 293. — B, Phycomyces nitens Kze. Plant grown on decoction of plums ; mycele, ;//, spo-
rophore, g. A,~ C, and Z>, Mucor Mucedo L. A, sporange in optical longitudinal section.
C, zygosperm (z) borne on suspensors. £, germ-tube ; g> sporange. D, conjugation.
a, a, gametes ; b, b, suspensors. (B slightly, A, C, and D more highly magnified.) (After
Brefeld.)

may be assumed, on the weighty authority of de Bary, that in certain of
these they do not occur, since industrious observation has failed to dis-
cover them. They are known, in fact, only in nineteen species, though
future research may bring a fair number more to light. Where they have
been observed the life-history proceeds as follows. The germinating

ZYGOMYCETES 337

zygosperm gives rise directly to a promycele bearing the characteristic
spores, and these in turn produce on germination a mycele which bears
spores again, and ultimately a zygosperm. It has been observed in an
artificially nourished individual, that the germinating zygosperm at once
produced a mycele which subsequently bore spores without the inter-
vention of the promycele stage. In another instance (Sporodinia grandis,
Link) zygosperms have been observed on a mycele which arose from a
spore, before the production of sporophores upon it ; while it sometimes
happens in this species that a zygosperm is produced on a mycele arising
directly from a zygosperm without the intervention of spores at all. But
in the great majority of cases the production of spores precedes the
formation of a zygosperm on the same mycele. In many species the
zygosperms are of rare occurrence, and an indefinite number of succes-
sive spore-bearing generations come between zygosperm and zygosperm.
Throughout the whole order spores are produced in vastly greater
numbers than zygosperms. Syzygites (Ehrenb.) is the generic name given
to certain forms of doubtful affinity which produce, so far as is known,
zygosperms alone.

Sub-order i : MUCORE^E. — The members of this group are for the
most part saprophytes on the excrement of animals, fruits, bread,
saccharine fluids, £c. The thallus-hyphse are relatively large and much
ramified. The conjugating hyphae arise either as branches of the
mycele or on special hyphae somewhat resembling sporangiophores,
their place of origin being, in different instances, in either morphological
or merely local approximation to each other. At an early stage of
development they come into contact by their apices, and a firm connec-
tion between the two is established. Thus joined the development of
each goes on, and soon a transverse wall cuts off the apical portion of
each. This portion is a gamete, and the rest of the hypha, generally
club-shaped, its suspensor. A pore next appears in the centre of the
original wall separating the two gametes, and gradually the whole wall
disappears and the contents conjugate. The zygosperm thus formed
increases in size, drawing upon the contents of the suspensors. The
protoplasm becomes dense, and the fatty contents gather into a large drop.
The wall commonly becomes covered externally with warts or spines at
all points except where the suspensors are attached. The form of the
whole is roundish or drum-shaped, the smooth walls adjoining the sus-
pensors corresponding with the sides of the drum. The wall is divided
into two coats, the outer one (extine} brown or black, and the inner one
(intine) stratified, and either entering the corrugations of the extine or
remaining smooth along the surface of contact with it. The suspensors
usually remain in statu quo, but in Rhizopus nigricans (Ehrenb.), where

z

338

FUNGI

one gamete is about half the height, though of the same breadth, as the
other, the suspensor of the smaller one becomes greatly enlarged after
conjugation, while the other remains as it was. In most cases the sus-
pensors eventually decay, but in others (Phycomyces, Kze., and Absidia,
Van Tiegh.) an outgrowth of darkly coloured hyphse takes place from
each suspensor and invests the zygosperm. In Mortierella (Coemans),
which has a smooth extine, this outgrowth arises from the hyphas bearing
the suspensors (as well as from the suspensors in one case), and forms a
compact integument of the zygosperm. In M. nigrescens (Van Tiegh.)
this outgrowth begins after conjugation, first from the suspensors, then
from the adjoining hyphas; while in M. Rostafinskii (Bref.) the outgrowth

FIG. 294. — Rhizopus nigricans Ehr. Formation of a zygosperm. Stages according to
1 tters ( x about 90). (After de Bary.)

takes place solely from the adjoining hyphae, and begins so early that an
investment is formed before actual conjugation takes place.

A phenomenon resembling that of the parthenogenesis of the Sapro-
legnieae is exhibited by a number of the Mucoreae in the formation vtazygo-
sperms. This occurs in Absidia, Sporodinia (Link), and Spinellus fusiger
(Van Tiegh.), and the formation of these bodies ensues when gametes
have failed 'to conjugate, and even when single gametes only are pro-
duced. They possess the structure and power of germination of normal
zygosperms, just as the parthenogenetic oosperms of Saprolegnia do.
Bainier states that Mucor tenuis (Link) forms only azygosperms, and
de Bary suggests that the (as yet little known) Azygites of Fries may be
found to exhibit this phenomenon.

On the germination of the zygosperm, as has been said, zpromycele
bearing sporanges is produced directly, and these sporanges have the

ZYGOMYCETES 339

same structure as those that follow them. They are globular sacs borne
at the end of sporangiophores, and the spores produced within them are
never endowed with the power of active movement. The different
forms of sporange and sporangiophore afford characters for the genera
of the group. Mucor (Michel.), Pilobolus (Tode), Sporodinia (Link),
Phycomyces, Rhizopus (Ehrenb.), Circinella (Van Tiegh.), and Absidia
possess a peculiar conformation of the basal wall of the sporange. It
bulges inwards in a conical or more or less oval form (see fig. 293 A), and
presents an appearance which has suggested the name of columel for
this peculiarity. Of 'the genera possessing a columel some are dis-
tinguished by a fugacious sporangial wall, others by a firm persistent
one, while the mode of branching of the sporangiophore (or the absence
of branching) and its general form, aiford other generic characters.
Morti.erella has a fugacious sporangial wall but no columel. Tham
nidium (Link), Chaetostylum (Van Tiegh.), and Helicostylum (Cord.)
have two kinds of sporange, the one kind like those of Mucor, and
the other smaller (sporangioles) with a persistent wall, no columel, '
and containing but a few spores, which however resemble the others in
function.

On old and on badly nourished myceles of some species, accessory
propagating bodies are formed (chlamy do spores, stylospores, &c.). All
such accessory spores are capable of giving rise to normal characteristic
myceles either at once or after a period of rest. In Mortierella single
acrospores are borne on slender mycelial hyphae. The old myceles and
even the sporangiophores of Mucor break up into resting-cells like those
of Saprolegnia with thick walls. The chlamydospores (Van Tieghem) of
Mortierella are such bodies, and where they occur terminally, de Bary
regards them as transitional forms to the acrospores of the same genus
just mentioned. Brefeld and Van Tieghem have described (Mucor
racemosus, Fres., &c.) another form of accessory propagating spores,
which are produced in series or chains through transverse division of
the mycelial hyphae. These either remain joined together in conferva
fashion, as Berkeley says, or they part company, and each such cell
exhibits a yeast-like vegetation.

Sub-order 2 : CH^TOCLADIE^E. — The mycelial hyphae of Chaetocladium
(Fres.) become attached to the hyphae of the Mucor-host, and, by the
resorption of the cell-wall at the place of contact, effect a direct com-
munication. At such places of attachment a large number of globular
protuberances are produced close together, forming a body of consider-
able size, which may be regarded as a food-reservoir. The act of con-
jugation and the formation of the zygosperm agree in all essential par-
ticulars with the corresponding processes in the Mucoreae. The intine

z 2

340

FUNGI

of the zygosperm has a smooth surface, not entering the external warts
of the extine. Azygosperms have not been observed. The sporophores
terminate in a fine hair-point, but below this give rise to a whorl of
branches nearly at right angles to each other, terminating again each in
a hair-point. These again branch more or less in like fashion. The
ultimate branches become swollen, and on these swellings fine short
sterigmata arise, each sterigma bearing a spore. The mass of spores
thus produced has a bunch-like aspect.

Cunningham's Choanephora, found by him on the flowers of Hibiscus,
appears to approach most nearly to Chaetocladium.

Sub-order 3 : PIPTOCEPHALIDE^E. — This very small group (Piptoce-
phalis, de By., Syncephalis, Van Tiegh.) is, like the last, composed of
parasites on the Mucoreae, and to this end the mycelial hyphae bear

haustoria, each of which
emits from its slightly
swollen base a small
crop of short delicate
rhizoids traversing the
Mucor-hypha affected.
The conjugating hyphas
of Piptocephalis are
arched somewhat like an
inverted D, the point
of contact being the
summit. Actual conju-
gation occurs, as in the

FIG. 295. — Piptocephalis Freseniana de By. and Wor. Con-
jugation and formation of a zygosperm, z. Stages in the
(After ~

order of the numbers ( x 650). (l

Brefeld.)

Mucoreae ; but when this
stage is reached, the pro-
duct of the conjugation

begins to swell at the point of union, and generally on the convex
side, into a globular body, which becomes echinulate as it swells.
When it has attained its full size and development at the expense of
the protoplasm of the united gametes, it becomes separated from them
by transverse partition, and remains seated, as it were, on the summit
of the arch. Though not the morphological equivalent of the zygo-
sperm of the Mucoreae, but rather the offspring of the original zygo-
sperm produced by the conjugation of the gametes, it will be most
convenient to regard it as the zygosperm. The sporophores bear at
their apices series or chains of spores produced by transverse partition.
In Piptocephalis the sporophore is dichotomously branched at the
summit, and each bifurcation bears a capitulum of chains of spores.
Accessory acrospores are sometimes produced by Syncephalis.

ZYGOMYCETES 341

De Bary ('Comp. Morph.,' p. 156) treats the incompletely known
Dimargaris and Dispira, both of Van Tieghem,' as at present doubtful
Mucorini, probably near Piptocephalideae. Another small group of
genera of doubtful position is formed by Kickxella(Coem.), Martensella

FIG. 296. — P. Freseniana. M, a mycelial tube of Mucor Mncedo, the host of Pipto-
cephalis. The mycele of the latter, m, penetrates M by haustoria, h. Z, zygosperm.
c, sporophore (x 300, the rest x 630). (After Brefeld.)

(Coem.), Coemansia (Van Tiegh. and Le Mon.); while Sorokin's Zygo-
chytrium, an aquatic saprophyte on dead insects, the account of which
needs confirmation, stands in a like uncertain position.

LITERATURE.

Bainier — Observ. sur les Mucorinees et sur les zygospores des Mucorinees (Ann. Sc.

Nat., 6 ser., Tom. xv., 1883).

De Bary und Woronin — Beitr. zur Morph. u. Physiol. der Pilze, i. and ii.
Brefeld — Bot. Unters. tiber Schimmelpilze, i. and iv.

342 FUNGI

Brefeld-Ueber Canning, iii. (Landvv. Jahrb., Thiel, v., 1876).

Coemans — Spicilege mycologique (Bull. Soc. Bot. Belg., i.).

Coemans— Quelques Hyphomycetes nouveaux (Bull. Acad. Roy. de Belgique, 2 ser.,

Tom. xv.).
Coemans — Recherches sur le polymorphisme et les different* appareils de reproduction

chez les Mucorinees (ibid,, Tom. xvi.).
Coemans — Monographic du genre Pilobolus (Mem. Couronn. de 1'Acad. Roy. d.

Belgique, Tom. xxx. ).
Cunningham— On the Occurrence of Conidial Fructification in the Mucorini, illustrated

by Choanephora (Trans. Linn. Soc. Lond., 2 ser., i., 1878).
Fresenius — Beitr. zur Mycologie, i. and iii.
Gilkinet — Mem. sur le polymorphisme des Champignons (Mem. Couronn. Acad.

Belg., Tom. xxvi., 1875).

Hildebrand — Ueber zwei neue Syzygites Formen (Pringsh. Jahrb., vi.).
Klein — Zur Kenntniss des Pilobolus (Pringsh. Jahrb., viii.).
Tulasne— Note sur les phenomenes de copulation, &c. (Ann. Sc. Nat., 5 ser., Tom.

vi., 1866).
Van Tieghem et Le Monnier — Rech. sur les Mucorinees (Ann. Sc. Nat., 5 ser., Tom.

xxvii., 1873).

Van Tieghem — Nouv. Rech. sur les Mucorinees (ibid., 6 ser., Tom. i., 1875).
Van Tieghem— Troisieme Mem. surges Mucorinees (ibid., 6 ser., Tom. iv., 1876).
Zimmermann — Das Genus Mucor (Chemnitz, 1871).

ORDER 2. — ENTOMOPHTHORE/E.

This small group of parasites inhabiting the bodies of insects agrees
with the Mucorini only in the formation of zygosperms. The mycele
vegetates within the body of the insect attacked, and consists either of
septate branching hyphae (Entomophthora, Fres.), or of a yeast-like mass
of cells (Empusa, Cohn). Zygosperms are formed, as described by
Nowakowski (Entomophthora ovispora, Nowak., and E. curvispora,
Nowak.), by the conjugation of adjacent hyphae which emit correspond-
ing lateral protuberances. These meet, become united in an H fashion
(somewhat as in Spirogyra), and enter thus into open communication.
As a result of this conjugation, there arises, either on the conjugating
branches or near them, a globular body, which develops at the expense
of the protoplasm of the united hyphae, and finally becomes cut off by
a wall. This must be regarded as a zygosperm, morphologically the
equivalent of that of Piptocephalis. Azygosperms occur in E. radicans
(Bref.) and certain species of Empusa, arising either as lateral out-
growths, or sometimes as terminal bodies. The cell-membrane of both
zygosperms and azygosperms -becomes much thickened and differen-
tiated into a thick extine, generally of regular outline, and a thin intine,
while • in the contents a large fatty drop appears. Zygosperms and
azygosperms both rest for a considerable period within the dead body

ZYGOMYCETES 343

of the host, the surrounding mycele disappearing. On germination,
which Nowakowski describes in Empusa Grylli (Fres.), a short pro-
mycele is emitted which bears a single spore.

Commonly, however, neither zygosperms nor azygosperms are
formed, and after the death of the insect, spores are produced on its
outer surface. In the case of Empusa — for example, E. Muscae (Cohn),
which attacks the common house-fly in large numbers in autumn— the
yeast-like mycelial cells, at the time of the death of the insect, send
forth each a tube, which bursts through the skin, and outside becomes
a short club-shaped sporophore bearing a single acrospore. Each
sporophore bears but one spore, and then perishes. The spores are
capable of germination at once, but the power lasts only for a few days.
Affected flies in this condition are common enough objects attached to
windows, &c., and surrounded by a whitish mass of spores. The
mycele of Entomophthora, which is septate, much branched, and often
anastomosing, sends branches through the skin to the outer surface,
where farther ramification takes place, investing the body of the insect.
These branches range themselves at right angles to the insect's body,
and terminate together at nearly the same elevation. Each such branch
is a sporophore, which, as in Empusa, forms a single acrospore. The
spores are capable of germination at once like those of Empusa ; and in
both genera either a very short tube is formed, bearing a secondary
spore, as in the promycele of the zygosperm, which, on germination, may
attack a fresh insect, or the germ-tube of the primary spore may do so
without the intervention of secondary spores.

Completoria complens (Lohde), found by Leitgeb in fern prothallia,
and Conidiobolus utriculosus (Bref.), described by Brefeld as a parasite
on Tremellini, are two forms placed here which, unlike the rest of the
group, do not attack insects. Brefeld, who has investigated the group
minutely, does not accept the conjugation as a real one, and brings
forward arguments against it based on the anastomosing of hyphae and
the situation of the zygosperms. His opinion, if accepted, would lead
to placing the group elsewhere ; but de Bary states (' Comparative
Morph.,' p. 159) that Nowakowski's and Brefeld's different observations
may be explained by the different behaviour of different species.

LITERATURE.

Brefeld Untersuch. liber die Entwickel. der Empusa Muscae und Empusa radicans

und die durch sie verursachten Epidemien der Stubenfliegen und Raupen.
(Abhandl. d. Naturforsch. Gesellsch. zu Halle, xii.).

Brefeld Ueber Entomophthoreen und ihre Verwandten (Sitzungsber. d. Gesellsch,

Naturforsch. Freunde zu Berlin, 1877). See also Bot. Zeit., 1877, p. 345.

Brefeld— Bot. Unters. liber Schimmelpilze (Ent. radicans), iv., 1881, p. 97.

344 FUNGI

Cohn — Empusa Muscae und die Krankheit der Stubenfliege (Nova Acta, xxv. , p. i).
Cohn — Ueber eine neue Pilzkrankheit der Erdraupen (Tarichium megaspermum)

(Beitrage zur Biologic der Pflanzen, Bd. i., Heft i, p. 58).
Eidam — Eine auf Excrementen von Froschen gefundene Entomophthoree (Bot.

Centralblatt, xxiv., 1885).
Fresenius— Ueber die Pilzgattung Entomophthora (Abhandl. d. Senkenberg. Ges.,

Bd. ii.).
Giard — Deux especes d'Entomophthora, &c. (Bull. Sc. du Depart, du Nord, 2 ser. ,

2 Ann., No. n).
Frey und Lebert — Die Pilzkrankheit der Fliegen (Verhandl. d. Naturf. Ges. zu

Zurich, 1856).
Leitgeb— Completoria complens, ein in Farnprothallien schmarotzende Pilz (Sit-

zungsber. d. Wien. Acad., Bd. 84, Abth. i).

Nowakowski — Die Copulation bei einigen Entomophthoreen (Bot. Zeit., 1877).
Nowakowski— Entomophthoreae (Abhandl. d. Acad. d. Wiss. zu Krakau, 1883).

Polish, see Bot. Zeit., 1882.
Sorokin— Zwei neue Entomophthora Arten (Cohn's Beitrage zur Biol. d. Pflanzen,

Bd. ii., Heft 3, p. 387).

ORDER 3. — CHYTRIDIACE^E.

The Chytridiaceae are a group of minute, more or less aquatic, parasitic
fungi, embracing forms which may, in the present state of our knowledge
of them, be thus classed together ; but whether it will eventually appear
that these are naturally related to each other, or are merely organisms
of different affinities presenting a similar appearance owing to similar
environment and ways of life, is but a subject for speculation. How-
ever, there are points in which all agree, and their life-history may be
briefly summarised thus : — Zoospores— mostly uniciliated ^the rest with
two cilia), and containing generally a drop of fatty substance, and, in
the larger forms at least, a nucleus — are produced in zoosporanges of
various forms and sizes. These escape from the apex of the zoosporange,
which is provided in some cases with a lid, either successively or in a
mass held together by a viscous substance, from which they are gradually
set free. An undulating alteration of outline, accompanied by amoeboid
movement, takes place in the zoospores of certain species towards the
end of the period of their activity. The zoospores give rise again to
zoosporanges. Resting-spores are known in certain cases, which like-
wise give rise to zoosporanges ; while in the Rhizidieas a process probably
intermediate between oogamous reproduction and isogamous con-
jugation takes place. Of the four sub-orders, the first (Rhizidiecz) is
manifestly nearly related to the Mucorini and the Ancylisteae ; the
second (Cladoehytrtece) may be regarded as allied to the Rhizidieae ; the
third (Olpidiece} and the fourth (Synchytriece) in all probability following
the second, De Bary suggests ('Comp. Morph.,' p. 169) that in

ZYGOMYCETES

345

this order the whole group may be looked upon as a lateral branch
of the Mucorini or Ancylisteae successively modified (degraded) by
aquatic parasitism, with its extremity represented by the Synchytrieae,
Woronina (Cornu), and Rozella (Cornu). De Bary also discusses (loc.
at.) the suggested relationship to such algae as Protococcaceae, Cha-
racium, Chlorochytrium, &c. Apart from the possession of chlorophyll,
the conjugation of zoospores in these algae separates them from the
Chytridiaceae, in which group such a process has not (at least as yet) been
discovered. Granting a relationship of the simpler Chytridiaceae with
Protococcaceae, &c., these might be regarded as leading up to Rhizidieae,
Ancylisteae, and Mucorini ; unless one regards the Chytridiaceae as com-
posed of two distinct sub-groups, Rhizidieas and Cladochytrieas, related
to Mucorini and Ancylisteae; and the Olpidieae and Synchytrieae to
Protococcaceae, &c. Only further research may determine these ques-
tions of affinity.

Sub-order i : RHIZIDIE^:. — The life-history of Polyphagus Euglenae

FIG. 297. — Polyphagus Englence Now. A, zoospore with drop of fatty matter and nucleus. £, young
plant attached to resting Euglena, e. C, zoosporange containing spores resting on empty pro-
zoosporange, a. D, conjugation : a, the receptive individual ; b, the supplying individual ; s, the
swollen end of conjugation tube (rudiment of resting-spore) ; e, e, e, the Euglenae. E, portion of
D five and a half hours later : b, empty, .y, mature; represent the same parts as in D. (A x 550,
-B, D, E, x 350, C x about 400.) (After Nowakovvski.)

(Nowak.), described by Nowakowski, furnishes us with the most highly
developed type of the whole group. The mycele consists of very slender
branching rhizoids, tapering each to a very thin point, and attaching
themselves to the Euglena-hosts. The original germinating zoospore

346 FUNGI

from which these arose remains, as it were, the centre of the system
of rhizoids, and, nourished by them, grows considerably in size. At
length, when it has attained full development, it becomes a pro%oosporange,
since from it there grows out a thick, cylindrical, thin-walled process,
into which all the protoplasm passes, and within which it breaks up
into zoospores. These, escaping, repeat the life-history. Zygosperms
(or oosperms) are produced by the conjugation of gametes, which play
unequal parts in the process. The one (supplying) individual is round
and larger than the other (the receptive) individual. A rhizoid from the
receptive individual places its apex in contact with the supplying indi-
vidual itself, and begins to grow in girth. The cell-wall at the place of
contact disappears, the protoplasm of both unites and passes into a
swelling which has arisen on the conjugating tube of the receiving indi-
vidual close behind the place of contact. This swelling then becomes
the zygosperm, which is provided with a thick wall, sometimes covered
with fine spines, appearing as early as the outset of the swelling process.
It happens— though rarely — that the tubes of two or three receptive in-
dividuals attach themselves to one supplying plant, and a corresponding,
number of zygosperms is thus formed. After a period of rest, the zygo-
sperm germinates by producing a zoosporange. Generation after gene-
ration of zoosporanges inteivene between zygosperm arid zygosperm.
* Which of the two should be called the male and which the female, is
not easy to determine. ... It is evident that we have before us an.
intermediate case between the ordinary forms of oogamous and iso-
gamous conjugation.' (De Bary, loc. cit., p. 163.)

A series of incompletely -known -forms may be placed beside Poly-
phagus (Nowak.), viz.: — Physoderma (Wallr.) (pro parte), Rhizidium
(A. Br.), Rhizophydium (Schenk), Obelidium (Nowak.), Chytridium
(A. Br.), Phlyctidium (A. Br.). Resting-cells of some of these have
been found, but their genesis is unknown.

Sub-order 2 : CLADOCHYTRIE^E. — This is a small sub-order, the
members of which mostly inhabit the tissues of marsh plants, and possess
copiously branching mycelial rhizoids, bearing terminal and interstitial
zoosporanges. The zoospores give rise on germination to a mycele like
the parent one. Resting zoosporanges occur. No process of conjuga-
tion is known either between filaments or zoospores. Cladochytrium
(Nowak.) and Physoderma (pro parte) compose the sub-order.

Sub-order 3 : OLPIDIE^. — The Olpidiese are wholly destitute of a
mycele, and the life-history, as described by Fischer for Olpidiopsis
Saprolegniae (Fisch.), and O. fusiformis (Cornu), which inhabits species
of Achlya, is a very simple one. The zoospores of O. Saprolegniae per-
forate the young mycelial hyphae of Saprolegnia, and, after a few days of

ZYGOMYCETES 347

growth in amoeboid fashion, a cell-wall is secreted, and each becomes a
zoosporange. Swellings arise on the mycele of the host as the result of
this parasitism. The zoosporange then sends forth a cylindrical process,
which perforates the wall of the Saprolegnia, and through it the zoospores
are discharged. The zoosporanges are either smooth and capable of
emission of zoospores at once, or are covered with fine spines and capable
either of emission at once or of resting. While the latter are generally
formed under adverse circumstances, it seems to occur with some regu-
larity that the zoospores of the smooth zoosporanges give rise to spiny
zoosporanges, and vice versa. The life-history of these two species may be
taken as typical, and the incompletely-known species of Olpidium (A.. Br.)
doubtless conform to it.

Sub-order 4 : SYNCHYTRIE^E. — The Synchytriese inhabit the epiderm
of terrestrial Flowering Plants, in which they excite the production of
small yellow or dark-red galls, owing to the abnormal swelling of the
epidermal cells affected. Like the Olpidieae, they have no mycele, but
they are distinguished from that sub-order by the formation of a sorus
of zoosporanges. From the germinating zoospore an initial cell is formed,
the contents of which break up into a sorus of zoosporanges. In
Pycnochytrium (de By.) ( = Chrysochytrium, Schroet., and Leuco-
chytrium, Schroet.) the initial cell is a resting-cell, which eventually
germinates by the gradual protrusion of its contents into a globular sac
seated upon the extine. Within this sac the sorus of zoosporanges is
formed by the division of the protoplasm. Each zoosporange pro-
duces a considerable number of zoospores, which again give rise to
resting-cells. In Eusynchytrium (Schroet.) an indefinite number of
sorus-forming generations, which at once produce zoospores, intervene
between resting-cell and resting-cell ; while in Synchytrium Taraxaci
(deBy.) the resting-cell produces a zoosporange without the intervention
of a sorus, a process suggestive of the Olpidieas. No conjugation of
zoospores nor any sexual process has been observed in any member of
the group.

WToronina and Rozella, which inhabit Saprolegniese, may be placed
with Synchytrieae.

De Bary (loc. at., p. 170) treats as doubtful Chytridiaceas (i) Tetra-
chytrium triceps (Sorok.), the zoospores of which are said to conjugate;
and (2) Hapalocystis mirabilis (Sorok.), the zoospores of which are
described as conjugating within the mother-cell. The observations,
however, require confirmation.

Beyond the general reference to Professor de Bary's ' Comparative
Morphology,' &:c., the student is specially referred to that source with
regard to this incompletely-known group.

348 FUNGI

LITERATURE.

De Bary — Beitr. zur Morph. u. Physiol. der Pilze, i. (Physoderma [Cladochytrium]).
De Bary und Woronin —Beitr. zur Kenntniss der Chytridieen (Ber. Naturf. Ges.

Freiburg, Bd. iii. ; and Ann. Sc. Nat., 5 ser., Tom. iii.).
Woronin — Neuer Beitr. zur Kenntniss der Chytridieen (Synchytrium Mercurialis)

(Bot. Zeit., 1868, p. 81).
Woronin- Chytridium Brassiere (in his paper on Plasmodiophora, Pringsheim's

Tahrb. wiss. Bot., Bd. xi.).

Braun — Ueber Chytridium, &c. (Monber. und Abhandl. Berl. Acad., 1855).
Braun — Ueber einige neue Arten der Gattung Chytridium und die damit verwandte

Gattung Rhizidium (Monber. Berl. Acad., 1856).
•Cienkowski — Rhizidium Confervas glomeratas (Bot. Zeit., 1857).
Cohn — Ueber Chytridium, &c. (Nova Acta Leop. -Carol., xxiv., Pt. i., p. 142).
Cornu — Chytridinees parasites des Saprolegniees (in Monogr. d. Saproleg., Ann. Sc.

Nat., 5 ser., Tom. xv., p. 112).

Fisch — Ueber zwei neue Chytridiaceen (Sitzber. d. phys. med. Soc. zu Erlangen, 1884).
Fischer — Ueber d. Stachelkugeln in Saprolegniaschlauchen (Olpidiopsis) (Bot. Zeit.,

1880).
Fischer — Untersuch. liber die Parasiten der Saprolegnieen (Pringsh. Jahrb., Bd. xiii.).

(Berlin Habilitationschrift, 1882).

Fischer — Zur Kenntniss d. Chytridiaceen (Erlangen, 1884).
Kny— Ueber Entwickelung des Chytridium Olla (Sitzber. d. Berl. Naturf. Freunde.

See also Bot. Zeit., 1871, p. 870).
Nowakowski— Beitrage zur Kenntniss d. Chytridiaceen (Cohn's Beitr. zur Biol. d.

Pflanzen, ii.).

Nowakowski — Polyphagus Euglense (ibid., ii. ).

Schenk — Algol. Mittheilungen (Verhandl. d. Phys. Med. Ges. zu Wiirzburg, Bd. viii.).
.Schenk — Ueber d. Vorkommen contractiler Zellen im Pflanzenreiche (Wiirzburg,

1858).
Schroeter— Die Pflanzenparasiten aus der Gattung Synchytrium (Cohn's Beitr. zur

Biol. d. Pflanzen, i.).
Schroeter — Uotersuch. liber die Pilzgattung Physoderma (Ber. d. Schlesischen Ges.,

1882).

Sorokin — Einige neue Wasserpilze (Tetrachytrium triceps) (Bot. Zeit., 1874).
.Sorokin — Uebersicht d. Gruppe Syphomycetes (Hapalocystis mirabilis) (Arbeiten d.

Naturf. Ges. an der Univ. Kazan, 1874, Bd. iv.). (See Just's Jahresbericht,

Thomas — Synchytrium cupulatum (Bot. Centralblatt, xxix.).

ORDER 4. — PROTOMYCETACE^E.

Protomyces macrosporus, Ung., to which there have recently been
.added a considerable number of species, many of them on insufficient
grounds, is a parasite on Umbellifers, especially ^Egopodium Poda-
graria, Meum athamanticum, and more rarely Heracleum sphondylium,
inhabiting the intercellular spaces of the leaf, petiole, stem, flower- stalk,
and pericarp. It possesses a branching septate mycele, at irregular
intervals on which there are formed interstitially large somewhat oval

ZYGOMYCETES

349

resting progametanges, with a stratified membrane and dense contents.
These persist when the mycele dies, and hibernate. After this period
of rest, and on liberation from the decaying tissues of the host (in
water), the intine, with the contents, bursts the extine, and, becoming
free, constitutes the gametange. Within it a large number of minute
short rod-shaped gametes are formed, while a portion of the proto-
plasm remains unused in the process. These gametes are ejected,
and, being without the power of spontaneous movement, they remain

FIG. 298. — Protomyces macrosporns Unger. a, a mature resting progametange ; b, gametange ; c, d,
and e, further stages of the same in the development of gamete?, c shows the parietal protoplasm,.
d the same divided into gametes, e the gametes rounded off and separated from the rest of the parietal
protoplasmic layer ( x 390). (After de Bary.)

in more or less proximity to each other. Where pairs of gametes
come together, they emit fine processes which conjugate, the whole
having the appearance of a dumb-bell or of the letter H. The germi-
nation of these has been observed on the epiderm of ^Egopodium ; it
takes place by the emission from one of the original gametes of a
germ-tube, to the nourishment of which the protoplasm of the united
gametes contributes. This germ-tube, on entering the tissues of the
host, repeats the life-history.

LITERATURE.

De Bary— Beitr. zur Morph. und Phys. der Pilze, i.
Von Thiimen — Eine neue Protomyces Species (Hedwigia, 1874).
Wolff — See footnote to de Bary's paper ' Protomyces microsporus und seine Ver-
wandten' (Bot. Zeit, 1874, p. 82).

Oilier literature of systematic interest in Saccardd's Sylloge.

ORDER 5. — USTILAGINE^:.

The parasites which are grouped together under this name affect
Flowering Plants of different natural orders, but are especially conspi-

350

FUNGI

<:uous as causing diseases of grasses. As a rule the attack of the para-
site is limited to one special region of the host, e.g. the ovary, or the
whole flower, or the leaf, or the stem, or even, in a few cases, the root ;
and when the fungus has attained its maturity, the result commonly is
that the part affected has been destroyed with the exception of the epi-
derm or integument and the remains of vascular tissue, and is replaced
by a powdery mass of brown or black resting-spores. The mycele sends
its long thin hyphae mostly along the intercellular spaces, in many cases
•emitting branched haustoria into the adjoining cells, and the resting-
spores are formed either on all parts of
the hyphae or on particular branches.
The life-history, briefly stated,
begins with the production from the
resting-spore of a promycele which
bears sporid-like gametes ; these
gametes conjugate in pairs, and the
united pair either directly produce
a new mycele, or sporids which do
so. This mycele then bears resting^
spores again in another host. Varia-
tions on this course of life-history
will be mentioned later on. Though
these conjugating gametes differ from
those of Protomyces in their acro-
genous origin on a promycele, they
may yet be considered homologues of
those, just as the acrogenous spores
of Chaetocladium are undoubtedly
homologous with the endogenous
spores of Mucor.

In Entyloma (de By.) the resting-spores are borne interstitially at
indefinite intervals on the mycele, as in Protomyces ; in Tilletia (Tul.)
they occur singly, and only terminally on the spore-bearing hyphae ;
while in Geminella (Schroet.) they are borne, two together, in series
throughout the length of the special hyphae. In Urocystis (Rabenh.),
Sorosporium (Rudolphi), and Tuburcinia (Berk.) they are united,
several together, into a kind of coil, which is invested with a transitory
or a persistent integument. With the exception, perhaps, of Graphiola
(Port.), the exact relationship of which to the Ustilagineae has yet to be
determined, Sphacelotheca Hydropiperis (de By.), formerly Ustilago
Hydropiperis, according to de Bary's description, affords the best
example of a well-developed stroma. This fungus attacks the ovule of

FIG. 299. — Tilletia caries Tul., germinating.
In «, gametes on promycele,/. In b, ga-
metes, s, conjugate in pairs. In c, a germ-
tube proceeding from pair of gametes, s.
A', a. sporid ( x 460). (After Tulasne.)

ZYGQMYCETES 351

Polygonum Hydropiper, and replaces it by a dense plexus of hyphse,
which exhibits a differentiation of a thick outer wall enclosing the
whole, a cylindrical columel, both colourless, and a dark-violet mass
of resting-spores filling up the space between. An undifferentiated
basal portion discharges the function, as it were, of a meristem, and
adds new elements to wall, columel, and spore-mass. The fungus
attacks only the ovule ; and as it grows thus in bulk, the unaffected
wall of the ovary is burst, and exposes the brittle wall of the sporal
mass, which breaks at the slightest touch, and sets the resting-spores
free.

The germination of the resting-spores, which are usually round or
many-sided, and possessed of both intine and extine, the latter often
covered with characteristic fine granulations, varies according as it takes
place in water merely or in a nutritive fluid. In water only the resting-
spores of Entyloma, Tilletia, Tuburcinia, and Urocystis produce a
short promycele-tube, which bears simultaneously on its blunt apex
a whorl, or ' crown ' of elongated gametes, varying in number. Many
species of Ustilago (Pers.) and Tolyposporium (Woron.) produce a
prornycele-tube which divides into a number of cells, from each of
which bud off laterally rod-shaped sporids or gametes, somewhat as a
yeast-cell buds off. The resting-spores of Thecaphora Lathyri (Kuhn)
and Ustilago longissima (Tul.) give rise to a short slender promycele-
tube, which bears an acrogenous sporid, or several serially ; while in
Thecaphora hyalina (Fingerh.), Ustilago carbo (Tul.), and U. destruens
(Tul.) it divides into several cells, each of which produces, if any,
only one sporid.

The conjugation of gametes in pairs takes place either before or
after separation from the promycele, by means of short or long cross
hyphse, according to the distance between them. The product of this
union is the outgrowth from the connected gametes of a mycelial germ-
tube, or, as occurs in Tilletia, Entyloma, Tuburcinia, and Urocystis,
sporids are produced on the outgrowth from the connected pair, and
these then emit mycelial germ-tubes. In a number of forms gametes
are constantly produced which do not conjugate, but give rise to
mycelial germ-tubes, as sporids do, while in Sorosporium Saponariae
(Rudolph.) the resting-spore itself emits the mycelial germ-tube directly,
without the intervention of promycele, gametes, and sporids. What
occurs regularly in these species may occur exceptionally in the case of
individuals the gametes of which ordinarily conjugate ; that is, they
may fail to produce gametes or sporids at all, or their gametes may fail
to conjugate, either all of them, or, where the number of gametes is. an
uneven one, the odd gamete. In such exceptional instances the

352 FUNGI

resting- spore or the single gamete, as the case may be, produces a
mycelial germ-tube, as a sporid does.

When the resting-spores germinate in nutritive fluids, as the ex-
periments of Brefeld show, the product is, according to the species, either
directly a mycele which bears spores, or an abundant yeast-like out-
growth from the promycele. In cases where the resting-spores failed to
germinate, they were permitted to do so in water, and the sporids so
formed, on being introduced into a nutritive fluid, gave rise to myceles
bearing acrospores, resembling, as the case might be, either the gametes
or the sporids.

Accessory acrospores resembling the sporids are borne on branches
of the mycele of certain species of Entyloma before the production of
resting-spores. The branches of the mycele which bear them protrude
through the stomates and epiderm of the host. They probably give
rise to new myceles, as the spends" do. The same thing occurs in
Tuburcinia Trientalis (Berk.), only here the accessory spores differ in
form from the promycelial sporids. They produce in this case un-
doubtedly each a mycele which bears resting-spores.

Brefeld regards the conjugation of the gametes as a merely vege-
tative process, and in no way analogous to any sexual act. De Bary
('Comp. Morph.,' p. 182) subjects Brefeld's arguments to destructive
criticism, while stating Brefeld's case in the fairest terms. While the
student is referred to the source quoted for the details, it may be shortly
stated that de Bary's arguments are broadly based on the regularity
with which conjugation occurs, and on the fact that it takes place
equally regularly in pairs, under the normal conditions of germination
in water. He shows, besides, conclusively how the process differs from
the well-known vegetative anastomosing of hyphae, £c.

De Bary regards the higher forms of Ustilagineae, such as the coil-
forming. Urocystis, Sorosporium, and Tuburcinia, and Sphacelotheca
with its well-developed stroma, as connected through the simpler forms
(e.g. Entyloma) with Protomyces. Both produce (in the one case acro-
genous, in the other endogenous) conjugating cells of equal value. The
next indicated ally is Cladochytrium, the spores of which are zoospores
(a matter not affecting the homology), but these fail to conjugate so far
as is known. At all events the nearest ally appears to be, in the present
state of our knowledge, that group of Chytridiaceae to which Cladochy-
trium belongs, through Entyloma and Protomyces.

The peculiarity is to be noted that in Protomyces and the Ustila-
gineae the act of conjugation takes place at a stage of the life-history
which bears no homology with the sexual states of other Phyco-
mycetes.

ZYGOMYCETES 353

LITERATURE.

De Bary — Untersuch. liber die Brandpilze (Berlin, 1853).

De Bary -Protomyces microsporus und seine Verwandten (Bot. Zeit., 1874) (Enty-

loma).

Brefeld— Botanische Untersuchungen, v. (Leipzig, 1883).

Cornu — Sur quelques Ustilaginees nouvelles (Ann. Sc. Nat., 6 ser., Tom. xv.).
Fischer von Waldheim — Beitr. zur Biologic und Entwickelungsgesch. der Ustilagi-

neen (Pringsh. Jahrb. , Bd. vii.).
Fischer von Waldheim— Les Ustilaginees et leurs plantes nourricieres (Ann. Sc. Nat.,

6 ser., Tom. iv. )t

Ed. Fischer — Beitr. zur Kenntniss der Gattung Graphiola (Bot. Zeit., 1883).
Kuhn - Die Krankheiten der Culturgewachse (Berlin, 1858).
Prillieux— Quelques observ. sur la formation et la germination des spores des Uro-

cystis (Ann. Sc. Nat., 6 ser., Tom. x.).
Schroeter— Bemerk. u. Beobacht. iiber einige Ustilagineen (Cohn's Beitrage zur

Biologic der Pflanzen, Bd. ii.).
Tulasne — Mem. sur les Ustilaginees comparees aux Uredinees (Ann. Sc. Nat., 3

ser., Tom. vii.).

Tulasne — Second Mem. sur les Uredinees et les Ustilaginees (ibid., 4 ser., Tom. ii.).
Ward — Entyloma Ranunculi, Proc. Roy. Soc., xli. (1886).
Winter— Einige Notizen iiber d. Fam. d. Ustilagineen (Flora, 1876).
Wolff — Beitr. zur Kenntniss der Ustilagineen (Bot. Zeit., 1873).
Wolff- Der Brand des Getreides (Halle, 1874).
Woronin — Beitr. zur Kenntniss der Ustilagineen (Tuburcinia). (De Bary und

Woronin's Beitr. zur Morph. u. Phys. d. Pilze, v.).

The older literatttre will be found quoted in Tulasne, Fischer von Waldheim, and in
de Barfs ' Brandpilze. '

GROUP II.— SPOROCARPE^E.

Class XX — Ascomycetes.

THE SPOROCARP.

This large class is distinguished by the universal formation of spores
in asci, for the most part tubular in shape, but sometimes broadly ovate
or roundish, and borne terminally on special hyphae termed ascogenous
hyphce. When an ascus has reached its full size, and only then, the
formation takes place within it of ascospores by free -cell formation. The
young ascus is at first filled with finely granular protoplasm, which con-
tains a nucleus, and within it a smaller body, probably a nucleole. The
protoplasm next gathers itself together at the upper part of the ascus,
while a watery fluid occupies the remainder of the cavity except a thin

A A

35*

FUNGI

layer of protoplasm coating the wall. At this stage the full growth of
the ascus is commonly reached, and the formation of ascospores begins
with the division of the nucleus into two ; then by the same process
four appear, then eight, which in the majority of cases represents the
number of ascospores. In many Ascomycetes, however, other numbers
typically prevail, e.g. one, or two, or four, or sixteen, forty, fifty, and so
on to over a hundred. Dothidea (Fr.), for example, has two to four, Sor-
daria (Ces. and De Not.) four, sixteen, sixty-four, and one hundred and
twenty-eight. Whatever the number, the nuclei always possess the same

FIG. 300. -Peziza (Pyroncma) confluens P. a, small portion of hymenium ; /, paraphyse attached'
to, not originating in, hyphal branches from which the three asci spring ; m, young asci ; r w,.
successive stages, according to letters, in the development of ascospores within asci ( x 390). (After
de Bary.)

structure in all stages of multiplication, but they become smaller in
size as the number advances. Round each nucleus there gathers a clear
mass of protoplasm, and ultimately this becomes enclosed by a mem-
brane, and, growing in size, thus develops into a spore. The ascospores
are arranged in a series, one over the other within the ascus. The
protoplasm left over within the ascus and outside the spores differs from
that within the spores in exhibiting a reddish or violet-brown colour
after treatment with iodine solution. De Bary originally proposed the
term * epiplasm ' for this portion of the contents ; but, Errera having^

ASCOMYCETES 355

shown that it contains a relatively large proportion of glycogen, he has
more lately (' Comp. Morph.,' p. 77) adopted for it the term glycogen-mass
or simply the glycogen. In certain cases the separation of the glycogen
from the protoplasm takes place before the formation of spores, the
former occupying the lower part of the ascus, and in some instances
both the apical and the basal portions on either side of the protoplasm
in which the nucleus is situated and the ascospores are formed.

Such are the asci which characterise the great class of Ascomycetes.
They are borne as a rule in considerable numbers mostly between hair-
like bodies, the paralyses, and united into hymenia within special sporo-
carps. The sporocarps are either seated on a fine mycele or they are
borne on a large stroma (thallus), which assumes in different genera
diverse characteristic forms. The whole body of the Ascomycetous
type is always built up of septate hyphse.

The sporocarps are composed of two main elements — of the asci with
the ascogenous hyphse, and of the envelope including paraphyses. These
two elements, though much interwoven with each other, are of dis-
tinct origin. The paraphyses, for example, are never borne by the asco-
genous hyphae, and the asci never by the cells of the envelope ; at all
events the one thing certain about so-called exceptions is their doubtful
character. According to the structure of the mature sporocarp, the
Ascomycetes may be classed in three divisions : the Discomycetes^ with
discocarps or apotheces (hymenia exposed) ; the Pyrenomycetes, with
pyrenocarps or peritheces (hymenia within flask- shaped bodies open at
the neck) ; and a third assemblage of forms with cleistocarps (enclosed
hymenia).

The hymenial disc of the apothece, consisting of asci and paraphyses
placed perpendicularly to the surface, is when ripe fully exposed. The
asci are imbedded, so to speak, in the paraphyses, and the whole mass
terminates in a regular surface. The paraphyses originate beneath from
a dense plexus of hyphae called the subhymenial layer or hypothecey
directly continuous with the outer envelope termed the exciple or with
the tissue of the stroma as the case may be. The paraphyses thus form
a part of the envelope-tissue as distinguished from the ascus-apparatus.
The ascogenous hyphae are interwoven with those hyphae of the hypo-
thece which bear the paraphyses. Terminating upwards in the asci
they are barely otherwise distinguishable in the mature apothece, unless
in certain cases by their greater size and the blue colour they assume
after treatment with potash. The asci grow up between the paraphyses^
and reach the surface, as has already been indicated, about the period
of ripening. As a rule the apothece exhibits a regular progressive
marginal growth, with, in a considerable number of cases, an intercalary

356 FUNGI

'growth in addition, giving rise to irregularities of shape. The basin-
shaped apotheces of Peziza (Discomycetes) and of the gymnocarpous
lichens are the characteristic forms, while with them may be placed
the large stromata of Morchella (Dill.) and allied genera, which are
club-shaped and in the form of stalked caps. The Hysterinese and
the Phacidiaceae, Ascobolus (Pers.), Pyronema (Fckl.), &c., which
show no marginal extension, approach the Pyrenomycetes in this
respect.

The perithece does not differ essentially from the apothece. As a
rule it is much smaller, rarely more than one millim. in diameter, and it
consists of an outer wall enclosing an ascogenous hymenium at all
points but one narrow opening, the ostiole. The whole perithece is
round or flask-shaped, and the ostiole is simply a pore in the wall or a
channel through the neck of the flask. In other words, while an
apothece is generally larger, it does not differ in any marked way from
a perithece, except that its hymenium has an open surface, while the
margin of the perithece is arched over, leaving only a narrow opening
for the escape of the spores. The asci arise from ascogenous hyphae,
either exclusively at the base of the perithecial cavity or at all points of
the inner surface, and in successive crops, producing in all a considerable
number of ascospores. The envelope consists of a wall which, when a
stroma is absent and the peritheces appear singly on the mycele, is com-
posed of a dense pseudo-parenchyme clothed sometimes externally with
hairs. Where the peritheces are borne on a stroma there is no sharp
differentiation of wall-structure. The neck, when present, is but a pro-
longation of the wall, and the ostiole arises (for at first the cavity is fully
closed) as an intercellular passage either schizogenously by the separation
of tissue through unequal growth, or lysigenously by the absorption of
the tract of tissue originally occupying its place. In many cases it is
hard to say by which process it arises, and it is likely enough that both
sometimes have a share in it. One distinguishes here between para-
physes which arise and stand in relation to the asci as in the apothece,
and periphyses, by which is meant other hairs of like origin arising from
the hymenium at places where there are no asci — for example, in the
region of the neck. Sometimes the periphyses protrude through the
ostiole. They are always present in greater or less numbers, except,
according to Fiiisting, in Massaria (De Not.) ; while paraphyses are absent
from a number of genera, both of fungi and of lichens. In Chaetomium
fimeti (Fckl.) the perithece remains closed, and this transition form leads
us to the division which possesses cleistocarps.

Just as the peritheces are essentially folded over apotheces, so the
cleistocarps may be described in general terms as peritheces which

ASCOMYCETES

357

remain wholly closed. The spores escape from them by the decay or
the rupture of the wall by external agencies. The Tuberaceae, which
possess undoubted asci of peculiar form, are necessarily included
among the Ascomycetes, and, since little more is known of them than
the structure of the sporocarps, they may be most fittingly dealt
with here at the conclusion of the consideration of the mature sporo-
carp.

The formation of ascospores within the asci of Tuberacece (truffle family)
differs from the typical mode already described. In Tuber (Mich.) the
asci are globular, and a differentiation of glycogen from protoplasm takes
place, the glycogen forming as it were a layer next the wall. In the proto-
plasm cavity, which is separated from the glycogen by a sharply outlined

FIG. ~$oi. — Tuber rnfnm Pico. «, section seen in reflected light. The white veins, /, contain air,
the dark ones, v, fluid ; h, hymenial tissue, b, a thinner section seen in transmitted light, lettering
as in a, white and dark appearance of veins reversed. (« x 5, b x 15.) (After de Bary.)

layer, the nuclei (4-6 in number) are formed, and young ascospores
appear — one or more only, however, developing, while the rest are
arrested and ultimately disappear. In Elaphomyces (Nees ab Esenb.)
the process is somewhat similar, though here no glycogen is dif-
ferentiated.

The sporocarps of the Tuberaceae, which are mostly large subter-
ranean bodies, are borne on a fine mycele, usually vanishing at the time
of maturity. They are either attached to the mycele only at their bases
or are completely invested by it. Very little is known as to the life-
history of any of the forms, but the structure of the sporocarps has been
accurately and exhaustively detailed. These are enclosed by zperidium,
the outer surface of which is frequently corrugated irregularly (Tuber)
or regularly (Hydnobolites, Tul., Genabea, Tul.), sometimes covered

358 FUNGI

with wart-like excrescences, or quite smooth. This peridium consists of
a pseudo-parenchyme of densely compacted hyphae, showing, in the
case of Stephensia (Tul.), separate layers. The external cells are denser
and thicker-walled than those within, but a gradual transition takes
place from one to the other, and again from the latter to the cells com-
posing the veins or seams of tissue which traverse the interior and
divide the spore-bearing tissue into chambers. The walls of such
chambers in Genabea (Tul.) possess a pseudo-parenchymatous structure
like the peridium, but in general such walls consist of a looser tissue.
Only by the perishing of this peridium or its rupture by external agencies
do the spores escape.

Certain authors divide the Tuberaceae into two families, the Tuberece,
containing Tuber, with an assemblage of allied genera mentioned below ;
and the Elaphomycec^ containing Elaphomyces, Onygena (Pers.), and
Penicillium (Link). Though the sporocarps of Elaphomyces and Peni-
cillium undoubtedly resemble each other, there is at all events as yet
hardly sufficient ground for going so far as to assume for Elaphomyces
'(or Onygena) the life-history of Penicillium. Onygena again, though
it may be placed beside Elaphomyces, is hardly near enough morpho-
logically to deserve other than a provisional juxtaposition.

Of the Tuberece, Hydnobolites is the simplest, with asci distributed
through the internal tissue, and the peridium represented only by the
outer layer of sterile hyphae. Genabea, with a regularly corrugated peri-
dium and asci arranged in groups imbedded in tracts of sterile hyphae,
forms another type with Terfezia (Tul.), in which the large masses of
fertile hyphae are separated by branching white seams of sterile tissue.
These sterile tracts or seams proceed inwards from the thick peridium.
There is a third type, characterised by a stout peridium enclosing an
internal mass consisting of thick plates of tissue, which proceed from
tthe peridium, and are separated by many narrow channels or chambers.
The wall of these chambers bears the hymenium. This type includes the
•remaining genera Tuber (truffles), Balsamia (Vitt.), Choiromyces(Vitt.),
Pachyphloeus (Tul.), Stephensia, Hydnocystis (Tul.), Hydnotria (B. and
Br.), and Genea (Vitt.).

Elaphomyces has a thick, hard, corky peridium consisting of two
distinct but united layers. The external one is thin, and either smooth
or warty ; the inner thicker, and composed of a dense plexus of thick-
walled hyphae. When ripe the internal substance consists of a dark
mass of spores traversed by a delicate cobweb-like capillitium which
arises from the inner surface of the peridium. Before maturity the asco-
genous hyphae may be recognised by their greater diameter than the
capillitium-hyphae, but they vanish with the ripening of the spores.

ASCOMYCETES

359

According to Boudier (Bull. Soc. Bot. France, xxiii., 1876), Elapho-
myces is probably parasitic on roots ; but this is not certainly esta-
blished.

In Onygena, which inhabits animal remains, the peridium is stalked,
and the ascospores (eight in each ascus) become free through the dis-
appearance of the ascus when ripe, and ultimately escape on the rupture
of the peridium.

ORIGTN OF THE SPOROCARP.

The following types, selected by de Bary (' Comp. Morph.,' p. 197)
as illustrating the origin of the sporocarp of the Ascomycetes, show
an amount of variation in this process which, it may be anticipated,
will be extended with farther research into the subject, while certain
gaps between these types
may be filled up. Taking
the most simple instance of
the origin of such a sporo-
carp, that of Eremascus albus
Eid. described by Eidam,
the sexual act preceding the
formation of the sporocarp
is manifestly the conjuga-
tion of two sexual elements
of identical structure. Two
cells of the septate mycele

Send forth, Close by the FIG. 302.— Eremascus albus Eidam. Fertilisation and
i'i ,1 formation of sporocarp. Stages in order of letters. In

Septum Which partS them, /the ascospores are formed ( x 900). (After Eidam.)

-each a short lateral tube,

the two tubes being not only exactly alike but in close contact from the
outset. They continue to grow outward, winding round each other in
a spiral course, performing three or four revolutions apiece. At this
stage a septum gro\vs across the base of each tube, and the apices con-
jugate. As a result of this act, a globular swelling arises at the apex,
the protoplasm of the tubes is withdrawn into it and enclosed by trans-
verse walls growing across the tops of the tubes. Within this body
(an ascus), which so strikingly resembles a simple zygosperm, there are
subsequently formed eight ascospores. [The carpogone itself becomes an
.ascus here.]

The next type embraces such forms as the Erysiphese, Eurotium,
Penicillium, Sordaria, Melanospora from among cleistocarpous and
pyrenocarpous forms ; and Gymnoascus, Pyronema, Ascobolus from
gymnocarpous and discocarpous fungi, and the Collemaceoe (discocarpous)

360 FUNGI

from the lichens. It is characterised by the production on the mycele
or the thallus-hyphcE of a body consisting sometimes of a cell, sometimes
of a chain of cells, called the carpogone, or with reference to its function the
ascogone, since from it there arise the ascogenous hyphce. (In Podosphaera,
' a genus of Erysipheae, a single stalked ascus only is formed.) In this
type the sexual act which precedes the farther development of the carpo-
gone is distinctly of a higher character. In such forms, as Pyronema and
Eurotium an antheridial filament is produced which fertilises the tricho-
gyne, as the special conjugating portion of the carpogone is called ; and
in the Collemaceae detached male cells, pollinoids, formed in special
antherids, often described as 'spermatia' and 'spermogones/are conveyed
passively to the trichogyne, and there, becoming attached, fuse their
contents into those of the trichogyne. There is a distinct difference here
between the sexual organs in the parts they play and in their structure ;
though in the Erysipheae, Penicillium, Sordaria, and Gymnoascus, the
actual process of fertilisation has not been observed, yet the constant
presence of the organs of sexuality justifies our regarding the function
as extremely probable. The case is not so strong with regard to-
Melanospora and Ascobolus, where the anftierid is either not constant
in its appearance, or with difficulty to be distinguished from the hyphae
of the envelope. A third type is that of Polystigma, which closely
resembles the Collemacese in the origin of the sporocarp. The carpo-
gone, trichogyne, and antherid with pollinoids are here very much the
same as in that group, only the sexual union has not been observed, and
there is present in the early development of the carpogone and surround-
ing it, a special coil of pseudo-parenchymatous hyphae which is ultimately
concerned in the formation of the envelope-tissue of the sporocarp.
Conforming also to the type represented by the Collemaceae, and more
especially allied^ to Polystigma in this respect, is the process as described
for Xylaria. Here too there is a special coil of hyphae, and in the
interior of it a chain of large cells (like the carpogone of Polystigma)
called by Fiiisting * Woronin's hypha.' This hypha vanishes, and no
connection has been discovered between it and the ultimate ascogenous
hyphae in the hypothece. Again no trichogyne has been observed to
arise from ' Woronin's hypha,' and therefore no union with it of pollinoids,
though bodies are recorded for Xylaria which resemble these male
organs. The difference in the origin of the sporocarp between this type
and Polystigma is essentially this : that here no distinct carpogone gives
rise to the ascogenous hyphae which have their origin in the special
coil mentioned, since ' Woronin's hypha ' disappears before this stage
in the development of the sporocarp. Sclerotinia sclerotiorum (de By.)
affords another type, since the ascogenous hyphae and those of the

ASCOMYCETES 361

envelope, which are unconnected with each other though interwoven
in the hypothece, may be traced down to the apparently uniform tissue
of the stalk. De Bary thinks, however, that these may have a distinct
origin — the ascogenous hyphse in those proceeding from the original
coil formed in the sclerote, and the envelope-hyphas in others springing
with them from the sterile tissue of the sclerote — that the coil in fact
may be (or may contain) a carpogone, though there is no sign of
antherid or pollinoids. The tracing of the continuity of these hyphae is
impossible throughout the long stalk with its uniform tissue. With this
type are to be classed the lichen-fungi investigated by Krabbe(Sphyridium,
Flot, Bseomyces, Pers., and Cladonia, Hill) the sporocarps of which
exhibit a clear distinction between ascogenous and envelope hyphae from
an early stage. The former, however, have not been traced to a carpo-
gone or other special initial organ, and neither antherid nor pollinoid
has been discovered. Such genera as Claviceps, Epichloe, Pleospora, &c.,
in which all that has been observed is a gradual specialisation of uniform
hyphae to the functions of ascogenous and envelope hyphae follow this
last type as the farthest removed from those forms described under the
second type.

COURSE OF DEVELOPMENT.

Within this large class several more or less distinct types of the
course of development may be recognised. Just as in the case of the
origin of the sporocarp, Eremascus albus is amorfg the simplest of all.
This remarkable type (the sporocarp of which is destitute of envelope-
tissue) possesses no other reproductive bodies than the ascospores pro-
duced in the single ascus which represents the sposocarp. That is to
say, the germinating ascospore gives rise to a thallus which directly bears
the sporocarp again. In the same case are also the Collemaceae with
probably all lichen-fungi, and Pyronema, Ascobolus, Gymnoascus, Hypo-
copra, and Sclerotinia sclerotiorum, which last, however, possesses other
propagating bodies in the shape of mycelial resting-cells comparable with
the soredes of lichens. Another type (to which Sclerotinia Fuckeliana,
de By. and Wor., belongs) is but one remove beyond this, since the
life-history may go directly from sporccarp to sporocarp, though in the
typical state acrospores intervene. Here the germinating ascospore
gives rise to a thallus which bears acrospores, or, as has been said, the
sporocarp again ; though never both together or successively on the same
thallus. The germinating acrospore in turn produces a thallus with
precisely the same properties and capabilities as that arising from the
ascospore, except that in some cases there appears to be a tendency to

362 FUNGI

go on producing other acrospore-bearing thalli. In a third type aero-
spores are always formed (so far as experience goes) on the primary
thallus produced by the germinating ascospore. This type de Bary
subdivides into two as follows : (a) the primary thallus arising from
the ascospore is only a promycele bearing sporids, which in turn
produce a definite thallus, which either bears a sporocarp at once, or
develops as sub-type (^). There is here then a necessary intervention of
acrospores (sporids) before the sporocarp is again formed. (/;) The
primary thallus arising from the ascospore is a definite one, which ulti-
mately bears the sporocarp, it is true, in all cases of complete develop-
ment, but not until acrospores have. been formed on it. The sub-type
to some extent suggests the first type, since the acrospores are not
morphologically a necessary intervention, though their appearance is
invariable. The thallus produced by the germinating acrospore
resembles the primary one in all respects. The development in this
type may stop short with the formation of acrospores, and this is often
repeated in succeeding generations.

The spores of such intervening states are invariably acrospores, and
they appear either singly or on hymenia on the free surface of the
thallus ; or they are produced in pycnids, bodies resembling peritheces.
The spores so produced are termed stylospores, or better, pycnospores,
as de Bary proposes. A species may produce only one of these kinds
of acrospore, e.g. Erysiphe ; or under favourable circumstances more
than one kind, e.g. Pleospora.

i. ERYSIPHE^E. — The mycele of the Erysipheae infests the surface
of green living plants, through the epiderm of which, it sends down
haustoria into the tissues beneath. The mycele is delicate and cob-web
like in appearance and consists of branching septate hyphae, and is
secured, so to speak, to the host-plant by means of the haustoria. In
the course of the branching of these hyphae they frequently cross each
other, and at such points of contact the sporocarp is formed. If Podo-
sphasra (Kze.), which has only a single ascus, be taken for the sake of
simplicity, its development may be described as taking place in this
fashion. From one of these crossing hyphae, at the point of contact
there springs an oval cell, the carpogone, which is separated by a
transverse wall from the hypha. From the other hypha, likewise at the
point of contact, there springs also a cell, longer and thinner than the
other, which is similarly cut off by a septum. It overtops the carpogone
to which it adheres, and the upper portion, which is slightly bent over
the carpogone, is farther cut off from the lower by a transverse wall,
The upper portion is the antherid and the lower its stalk. From the
hyphae at the base there now grow up a number of tubes, which envelop

ASCOMYCETES

363

the carpogone and form the single-layered outer perithecial wall. From
the inner surface of the cells composing this wall there subsequently
.arise a number of other cells forming an inner wall several cells thick.
The growth of these separates the antherid from the carpogone, and it
takes part in the formation of the outer wall. From the outer wall, the
cells of which have become larger and brown in colour, fine rhizoids are
produced near the base, and in some species a few fine hairs at the apex
termed appendicuke. Meanwhile the carpogone has divided into two
cells, one the ultimate ascus, and the other its pedicel-cell. Within the
ascus finally eight ascospores are formed.

In Erysiphe (Hedw.) the chief points of difference from Podosphaera

FIG. 303. — /, II, Podosphcera pannosa de By. and Wor. 7, chain of spores on sporophore and
mycele. //, ripe sporocarp with asous, a, emerging through wall of sporocarp, h. Ill— V, P.
Castagnei de By. and Wor., fertilisation. HJ , c, carpogone : p, antherid. IV, older state ;
h, hyphal branches of envelope. V, still older state in optical longitudinal section ; a, ascus
( x too). (I, II, after Tulasne, III— I', after de Bary.)

to be noted are these. The antherid winds spirally round the club-
shaped carpogone, which divides into a series of cells — produces a
number of asci — and the inner wall of the perithece is more developed.
The germinating ascospore gives rise to a mycele provided with
haustoria, on a suitable host, and from this thallus there spring short
sporophores which produce successively a series of acrospores. The
acrospores in turn produce a mycele exactly like the primary one from
the ascospore — which like it, if completely developed, ends by bearing
the sporocarp again. But owing to external conditions such as varying
weather, nutrition, and the like, this consummation is frequently not
reached, and acrospores only are then formed generation after generation.

364 FUNGI

For example, the acrospore form called Oidium Tuckeri (Berk.), which
occurs abundantly, and is well known as vine-mildew, never produces in
Europe, so far as is known, peritheces. These it is believed have been
found on native vines in North America, which is supposed to be the
home of the disease, the perithecial form being the fungus described as
Erysiphe (Uncinula) spiralis (Berk, et Curt.).

The Erysipheae are parasites infesting living flowering plants of many
natural orders. Among the best known and most destructive are the
above-mentioned vine-mildewr ; E. la*mprocarpa (Lk.) on Compositse,
Plantago, Verbascum, Labiatae ; E. graminis (Lev.) on grasses ; E.
Martii (Lev.) on Umbelliferae, clover, lucern, lupins, &c. ; E. communis
(Lk.) on Polygonum, Ruinex, Convolvulus, Dipsacus, Lathyrus,
Delphinium, Aquilegia, Ranunculus, &c. Podosphaera Kunzei (Lev.)
attacks species of Prunus, and Podosphaera Castagnei (de By.) is a well-
known mildew of hops, though it also attacks many other plants of
different natural orders.

2. EUROTIUM (Link). — The carpogone is formed by the rolling up
in corkscrew fashion of the tip of a mycelial hypha, the turns of which,
four or five in number, gradually come into closer contact till they pre-
sent the appearance of a hollow screw. It is then divided by transverse
walls into as many cells as there are turns in the screw. From the
bottom turn of the screw there grow up two or three branches of irregular
diameter, which take an irregular course towards the apex, but remain
in close contact with the outside of the carpogone. Sometimes one
ascends by way of the inside of the screw. One, however, climbs faster
than the others and reaches the apex first ; this is the antherid. Im-
pregnation by it having taken place at the apex of the carpogone after
the absorption of a minute portion of the wall, both the antherid and
the other branches of the basal turn of the carpogone which follow it
proceed to branch copiously, the hyphae being septate, until the carpo-
gone is completely enveloped. In this way the outer perithecial wall
is formed as in the Erysipheae. From it, as in the last type too, the
inner wall grows inward, filling up the space between the outer wall and
the carpogone with several layers, and pressing apart the turns of the
screw. The wall-cells are of a pseudo-parenchymatous appearance, and
the membrane of the outer wall becomes covered externally by a
golden-coloured substance. The whole of these envelope-cells, it should
be mentioned, increase in volume considerably. From the carpogone
there now proceed numerous ascogenous hyphae, which press among and
suppress the inner wall-cells, and, branching plentifully, bear at the ends
of the branches oval asci. These contain each eight ascospores. So
copiously does this take place that, of the ascogenous hyphae soon only

ASCOMYCETES

365

the traces may be seen, and by the time of maturity even the ascus-walls
disappear and the perithece contains little but ripe ascospores.

When the ascospore germinates it produces a mycele, on which there
shortly arise upright sporophores with round swollen apices bearing
numerous short sterigmata over the surface. On the sterigmata chains
of acrospores are formed successively, which, proceeding radially from the

FIG. 304. — Enrotium repens de By. A, branch of mycele with sporophore, c, and sterigmata, si;
early stage of carpogone at as. B '. spirally twisted carpogone, as, antherid, p, and an envelope-
hypha. C, older state with more envelope-hyphae. D, young sporocarp. E and F, young spo-
rocarps in optical longitudinal section. In E the inner wall is beginning to be formed ; iv , the

. outer wall ; f, the nner wall and other cells filling space between it and carpogone. G, ascus with
spores. //, ascospore of E. herbariorum Lk. (A x 190, the others x 600.) (After de Bary.)

apex of the sporophore, surround it with a globular mass of acrospores.
The course of development is the same here as in the Erysipheae, and
generation after generation of acrospores is usually formed in succession
without the myceles attaining to the formation again of the sporocarp —
this being the result of the external conditions of life of the fungus.

366 FUNGI .

The species of Eurotium are saprophytes, and are found inhabiting
decaying plants, fruits, &c., and forming in such situations a loose
mycele of delicate thin-walled cells. The common mould formerly
called Aspergillus glaucus (Link) is the acrospore stage of Eurotium
herbariorum (Link), and was believed to be an independent form before
de Bary discovered the pleomorphism of this fungus and identified it
with the sporocarp stage (Eurotium).

3. PENICILLIUM (Link). — The sporocarp of Penicillium takes its
origin in the winding round each other once or twice of two lateral
branches of mycelial hyphae. These are so like each other that it is im-
possible, from the observations. made on them, to say which is male and
which female — a question on which the ultimate development throws no
light, since it is uncertain whether the ascogenous hyphae proceed from
either or from both, and moreover, besides being alike in formation, they
are equal in activity. Neither has any observation been made of the
conjugation of these presumptive sexual elements— though their position
towards each other signifies a sexual union. Together with the out-
growths from these of numerous short asQogenous hyphae, there arises
from the neighbouring hyphae of the mycele a dense growth which com-
pletely envelops the presumptive carpogone and becomes interlaced
with the ascogenous hyphae proceeding from it— these being at first
thicker hyphae than those of the envelope-tissue. However, with the
growth of the whole body, the cells of the envelope increase considerably
in volume, especially the central mass, and acquire thickened pitted cell-
walls, while the layers nearer the circumference form themselves into an
outer wall the cells of which have yellowish-brown membranes. The
whole has a pseudo-parenchymatous appearance. The originally outer-
most cells are cast off, owing to their taking no part in the growth.
While this development of the envelope has been going forward, the
ascogenous hyphae have been pushing in between the interstices of the
cells, and sharing in the process of thickening of the cell-membranes.
At this stage of the history of the sporocarp a period of rest intervenes
lasting about six or seven weeks. This past, the ascogenous hyph?s
begin anew their growth in vigorous fashion, and, branching copiously at
the expense of the cells of the envelope, ultimately produce at the ends
of the branches short thick twisted terminal branches, which bear
serially strings of asci containing each eight ascospores. So far is this
process carried that finally not only is the whole interior envelope-tissue
used up, but the asci themselves disappear, leaving enclosed by the outer
wall only a dense mass of ascospores. De Bary compares the exist-
ence here of two forms of ascogenous hyphae — viz. the relatively slender
form which traverses and uses up the envelope-tissue, and the short

ASCOMYCETES 367

twisted thicker form which bears the asci — with the occurrence of the
two forms of hyphae in the ripening sporocarp of Elaphomyces. Some
authors, it may be remembered, place Penicillium and Elaphomyces side
by side.

The germinating ascospore produces a mycele in all respects like
that which bore the sporocarp, a much-branching anastomosing septate
flocculent mycele, which bears acrospores serially in succession at the end
of their characteristic sporophores. The sporophore arises from the mycele
in the form of an upright septate stalk, which bears at its summit cymose
branches ending in sterigmata of equal height. On the sterigmata are
the chains of acrospores. Such a sporophore has a brush-like appear-
ance, the stalk being the handle, and the branches, sterigmata, &c.,
the hairs. The sporophores arise in dense masses, and in all produce
enormous numbers of spores. So densely do they occur in exception-
ally favourable situations — in the case of Penicillium glaucum (Lk.)—
that they are sometimes bound together in bundles, fasciated as it
were, and bear at the summit a dense crown of chains of spores.
This form was originally described as a distinct genus by the name of
Coremium glaucum (Lk.). As in Erysiphe and Eurotiurn, so in Peni-
cillium, the course of development, after the production of acrospores,
may omit the formation of the sporocarp on the same thallus through
external conditions being unfavourable to its development. This, in
fact, is the usual case in Penicillium, and generation after generation
of thalli bearing acrospores only, and there stopping short, intervene as
a rule between sporocarp and sporocarp. Perhaps the commonest of all
moulds is Penicillium glaucum (Lk.), occurring on decaying fruits, or*
bread, &c., &c., in the acrospore-bearing condition. The sporocarp-
occurs, very rarely, in dark places where there is a poor supply of oxygen,,
and mostly on bread.

4. GYMNOASCUS (Baranetsk.) and CTENOMYCES (Eidam) do not
differ in any very striking peculiarity from types already discussed. The
origin of the sporocarp is characterised by the fact that while one sexual
hypha entwines the other, it is the entwining one which is the carpogone
— which subsequently produces the ascogenous hyphae — and the other,,
round which the carpogone winds, is the antherid. The relative posi-
tions of these certainly recall the case of Eurotium, where the antherid
occasionally ascends by way of the inside of the screw ; but here, on
the other hand, the carpogone takes, as it were, the active step, and
winds round the antherid. These have their origin as lateral shoots
either of the same hypha or of different hyphae ; or it may be that only
the entwining one (carpogone) is a lateral shoot, and the other merely
the intercalary portion of a hypha. The ascogenous hyphae branch.

368

FUNGI

•copiously, and ultimately bear at the ends asci containing each eight
.ascospores, and the envelope-tissue is contributed by shoots from the
neighbouring mycele and from the base of the carpogone.

As already mentioned above, no acrospore stage intervenes here
between sporocarp and sporocarp, i.e. the ascospore, on germinating,
produces a thallus, which again bears the sporocarp directly. Gym-
noascus is a saprophyte growing on dung.

5. ASCOBOLUS (Pers.). — The cafpogone arises on the mycele in the
form of a thick curved sausage-shaped lateral hypha, which becomes
•divided by transverse walls into six or seven cells, about as long as they

are broad. While in this stage the
farther end of it is clasped by the
branching end of a much thinner
hypha — like one of the ordinary my-
celial hyphae — which, it may be as-
sumed, is the antherid, from analogy
with those types already discussed.
At allx events, it soon loses its iden-
tity in the dense growth of envelope-
hyphae which,' immediately after
this stage has been reached, are
produced both from the ordinary
mycele and from the hyphae which
bear the carpogone and presump-
tive antherid. These envelope-
hyphae, which soon enclose the
carpogone in a round mass with
a differentiated rind, next proceed
to develop in the upper region over
the carpogone (which is situated
in the basal portion) the sub-

hymenial layer of a discocarp. From this subhymenial layer there
•rise upward the straight perpendicular paraphyses. By the time the
development has gone so far, the carpogone gives rise to a dozen or
more ascogenous hyphae from a cell near the middle of the row,
which has manifestly obtained from its neighbours contributions from
their contents. The ascogenous hyphae grow upward to the subhy-
menial layer, where they branch and spread about among the roots,
so to speak, of the paraphyses, and here bear asci. The asci grow
straight upward among the paraphyses to the hymenial surface. The
portion of the rind (envelope-tissue) immediately over the hymenial
surface is ruptured, in consequence of the expansion of this surface

FIG. 305. — Ascobolusfurfuraccus Pers. Young
sporocarp in longitudinal section (diagram-
matic), m. mycele ; A, hymenium ; c, car-
pogone with ascogenous hyphae, s, in the
subhymenial layer, and a, asci (shaded); /,
antherid ; p—r, tissue of envelope giving rise
to paraphyses. (After Janczewski.)

ASCOMYCETES

369

during growth, to permit the escape of the ascospores, and as new asci
are produced (mostly taking the place of older ones), the expansion often
continues till the hymenial surface becomes convex.

Ascobolus, like Gymnoascus, has no intervening acrospores, and the
germinating ascospore gives rise to a thallus which bears the sporocarp
directly. It is a saprophyte, and the species abound on dung.

6. PYRONEMA (Fckl.). — Pyronema confluens (Tul.) (or Peziza con-
fluens, Pers., as it was formerly called), which, when mature, forms a dis-
cocarp like Ascobolus, differs considerably from that genus in the struc-
ture of the carpogone and antherid, though both, doubtless, belong to

FIG.. 306. — Pyronema, conflrtens Tul.
chogyne marked / has not yet become

a, is in communication through t with ca
hypha; ( x about 300). (From de Bary, after

The tri-

'ne /, proceed-
the antherid,

one, c, which is swollen and emitting ascogenous
" "man.)

A : r, carpogones ; a, antherids ; t, trichogynes.
: united with a. B, older state. The trichogyne
ing from carpogone <r, and cut off by a transverse wall, is in open union with a. C : the antherid,

the same main type in this respect. On the mycele of Pyronemaycon-
fluens there arise clusters or rosettes of more or less club-shaped cells
by forked branching at the summits of erect hyphae, occurring generally
in pairs ; these pairs in turn having their origin in densely branched
groups of hyphae. The rosettes consist each of; three kinds of cell:
the broad club-shaped, slightly curved cells are carpogones, and are
usually borne on two pedicel- cells ; the antherids are also club-shaped, of
the same height, but of , about half the breadth ; and the third kind are
sterile cells of cylindrical form. Two or three pairs of carpogones and
antherids are included in each rosette. From the -top of the carpogone
there grows forth a slender curved trichogyne, with plentiful supply of

B B

370 FUNGI

protoplasm ; and this organ, instead of behaving passively in the opera-
tion, bends over till it touches the top of an adjoining antherid, to which
it adheres. When this has taken place, the trichogyne becomes separated
by a transverse septum at the base from the carpogone, and then,
through the dissolution of the intervening membrane, the contents of
trichogyne and antherid are mingled. After impregnation the carpogone
increases in volume, and from numerous points of its surface there are
emitted ascogenous hypha£. From the sterile cells and the whole basal
region of the rosette, the envelope-hyphae now grow forth and form a
large stroma enclosing the carpogones and antherids — the latter re-
maining almost unaltered, full of protoplasm, and taking no part in the
formation of the envelope— and upon the stroma a free hypothece
bearing the paraphyses. In the production of asci and the farther
development of the apothece, Pyronema agrees with Ascobolus.

Pyronema, like Ascobolus and Gymnoascus, produces no acrospores ;.
and sporocarp follows sporocarp without intervention on successive
thalli.

7. SORDARIA (Ces. and de Not.) and MELANOSPORA (Corda), both
Pyrenomycetous forms, are placed next Ascobolus by de Bary with
respect to the morphology of their sporocarps— of course excluding such
differences of form as are peculiar to their being Pyrenomycetes, while
Ascobolus is, as has been shown, a Discomycete. Fundamentally there
is little real difference in the mode of origin of the sporocarp ; and
Chaetomium and Ascotricha may eventually prove to belong to the same
series.

8. COLLEMACE^E. — In the Collemaceae, a group of discocarpous
lichens, the structure, development, and mode of behaviour of the male
sexual element is wholly different from any hitherto described, while
the carpogone remains of similar structure, though, of course, modified
to meet the requirements of the changed conditions. The male cells
are pollinoids formed in a flask-shaped antherid, somewhat resembling
a peiithece. It is sunk beneath the surface of the thallus, and opens
by means of a narrow neck. The flask consists of a wall of densely-
compacted hyphae, giving off towards the interior a layer of numerous
delicate hyphae (sterigmata), which converge towards the central portion
of the flask. These form at their apices successively in series numerous
pollinoids, which soon fill the central space. The pollinoids are thin-
walled rod-shaped cells, with an outer membrane of a gelatinous kind,
readily swelling and dissolving in water. In damp rainy weather water
gets access to the pollinoids, and through the swelling action mentioned
they are forced out through the neck of the antherid and dispersed
over the surface of the thallus. The development of the antherid

ASCOMYCETES

37i

generally somewhat precedes the origin of the carpogone. Under
the surface of the thallus a hypha not distinguishable from its neigh-
bours gives off a broader lateral branch, which coils itself up two or
three times, and then sends forth the tip of tha^coil, which, growing
upward, emerges through the surface of the thallus into the open. The
tube is commonly somewhat swollen as it passes through the superficial
tissue, and for some short distance above it, and attains a height above
the surface of four or five times its breadth. This is the trichogyne.
The coil as it grows is divided by transverse walls into about a dozen
thin-walled cells, and the trichogyne likewise into a similar number.
Its development having taken place, and the suitable conditions of
moisture having dispersed the pollinoids over the surface, these, wher-

B

FIG. 307. — A, Leptogium microphyllum Ach., section of thallus. a, point of trichogyne ;
g, algal cells ; /*, hyphae, B, Collema pulposum Bernh., young carpogone. C, tncho-
•gyne with pollinoids of L. microphyllum. D, a similar one showing union with polli-
noid. (A x 350, B, C, D x 750.) (After Stahl.)

ever they come into contact with a trichogyne, stick to it, sometimes in
considerable numbers, and an open communication between pollinoid
and trichogyne is established by means of a short minute process from
the pollinoid. When this has been accomplished the cells of the
trichogyne collapse, remaining distended only where a transverse septum
occurs in its course, while the cells of the coil increase in volume and
in number through the growth of fresh transverse walls. The neigh-
bouring thallus-hyphae then give out numerous shoots, which not only
grow round the coils, but press them asunder. The hyphae on the side
next the surface then give off branches in that direction, the end shoots
of which form the first paraphyses, after displacing the intervening tissue
in their course. The enveloping hyphae extend laterally until a basin-

B B 2

372

FUNGI

shaped pseudo-parenchymatous exciple is formed, the margin of which
reaches the surface. The interior of this basin is then soon filled with
upright paraphyses like those which originally attained the surface. The
turns of the original coil become unloosed, and eventually there are
given off from it ascogenous hyphae which, after branching in the sub-
hymenial zone like those of Ascobolus, finally produce successive asci
in the mature apothece.

In Physma Massal. the carpogone is produced from the hyphae
which form the wall of the antherid, and the trichogyne rises to the
surface outside the wall. Eventually the paraphyses and asci are pro-
duced in the place formerly occupied by the sterigmata of the antherid,

FIG. 308. — Leptogium microphyllnm Ach., young apothece in section, h, hyphae ; g, algal cells '
a, thalloidal exciple ; b, exciple proper ; c, hypothece. The apothece is filled with paraphyses,
among which may be seen bladder-shaped ascogenous hyphae with three young asci ( x 530). (After
Stahlj

and the antherid is thus transformed into the sporocarp. The species
of Collema (Ach.) have no acrospores, and resemble in the course of
their life -history Ascobolus, Pyronema, &c. For structure of lichen-
thallus, see p. 318.

9. POLYSTIGMA (Pers.) is a genus of parasitic fungi bearing a striking
resemblance to the Collemaceae in its sexual reproductive apparatus.
Antherids and pollinoids are formed differing in no material respect
from those of the Collemaceae — the pollinoids being in this case more
thread-like and bent. The genesis of the sporocarp is characterised
here, however, by the formation of a fundamental coil of hyphae smaller
than the thallus-hyphae. The carpogone appears among these, consisting
of a spirally-wound hypha of two or three turns, with broad short cells.

ASCOMYCETES 373

It traverses the fundamental coil, and its apex grows out as a trichogyne,
which protrudes through a stomate of the leaf of the host-plant. Pollinoids
have been observed attached to it, but so far no actual communication
has been detected. Accompanying the trichogyne are a few fine hyphae,
which, after the collapse of the trichogyne, protrude through the stomate
like the tip of a small brush. The farther development of the sporocarp
(the envelope-tissue arising from the fundamental coil) is like that of the
last type, with this difference, that, instead of an apothece, it is a perithece
which is here produced.

The ascospore produces on germinating a short promycelial tube,
the end of which bears a sporid. The sporid, on germinating in turn
on the leaf of a suitable host (Prunus), sends its germ-tube through the
outer wall of the epiderm, and branches within the epidermal cell,
these branches again penetrating into the parenchyme of the leaf. Here
a thallus is formed, which remains covered by the epiderm of the leaf of
the host until the sporocarp is again produced.

10. XYLARIE^E, &c. — In Xylaria (Hill), Hypoxylon (Bull.), Ustulina
(Tul.), Diatrype (Fr.), Stictosphaeria (Till.), Eutypa (Tul), Nummularia
(TuL), and Quaternaria (Tul.), we have the occurrence of a fundamental
coil preceding the formation of the peritheces, followed by the gradual
disappearance, as mentioned above for Xylaria, of ' Woronin's hypha,'
which is formed in it, without its taking part in the formation of the
ascogenous hyphae. These arise, together with the paraphyses, from
the perithecial wall. No trichogyne is formed from ' Woronin's hypha,'
and there are no antherids. Before the formation of the peritheces in
Xylaria there are borne on the same stroma in dense hymenia bodies
which resemble acrospores, or it may be pollinoids. In this genus they
have not been observed to germinate, though similar bodies germinate
freely in Ustulina, e.g., and other genera. In Xylaria at all events
they may be functionless pollinoids persisting in an organism in which
indications of a carpogone (in the form of 'Woronin's hypha ') also still
remain.

11. SCLEROTINIA (Fckl.). — The sporocarp of Sclerotiniasclerotiorum
(de By.) is in the form of a disc at first cup-shaped, borne at the summit
of a stalk arising from a sclerote. It takes its origin from an entangled
primordial coil of hyphse with gelatinous membranes situated just
beneath the dark peripheral cells of the sclerote. There are many such
coils in each sclerote, but they do not all attain this farther development.
The bundle of hyphae constituting the stalk of the sporocarp breaks
forth, as has been said, from this region of the sclerote, the central
portion of the hyphae arising from the coil, and the external hyphae from
the ordinary tissue of the sclerote. In the growth of the stalk it has

374 FUNGI

been found impossible to trace any anatomical distinction between these
elements, and therefore it amounts to no more than a probability that
the hyphae from the coil are the ultimate ascogenous hyphae ; while those
from the tissue of the sclerote may furnish the envelope-tissue of the
sporocarp. The main difference between the development of S. sclero-
tiorum and S. Fuckeliana in this respect consists in the primordial coil
of the latter originating not within the sclerote, but in the central portion
of the bundle of stalk-hyphae after it has reached the external surface.

S. sclerotiorum possesses, so far as is known, no intervening aero-
spores. The germinating ascospore produces a mycele on which sclerotes
are formed, and on these only the sporocarps again. S. Fuckeliana
sometimes does the same, and de Bary has observed a single instance of
the sporocarp being produced on the mycele without even the formation
of a sclerote. The sclerotes of this species, however, frequently produce
filamentous sporophores bearing acrospores, this stage being that
formerly known as Botrytis cinerea (Pers.). It never happens that a
sclerote bears both acrospores and sporocarps, either together or after
each other. The primary mycele may bear acrospores directly without
interfering with the subsequent production of sclerotes, but this does not
happen often. The mycele produced by the germinating acrospores is
similar in all respects to the primary one arising from the ascospore, with
the reservation that it has a greater tendency than the other to the pro-
duction of sporophores. In this species there are also often formed
certain abortive acrospores, or it may be pollinoids.

12. PLEOSPORA (Rabenh.). — In the origin of the perithece of Pleo-
spora herbarum (Rabenh.), the traces of sexuality disappear from view,
and indeed it is stated that the asci arise among the paraphyses as
branches of the basal cells of the latter. In the life-history of this
fungus a considerable number of forms are embraced. Besides the
ascospores, which are compound multicellular bodies, there are in the
second category acrospores of three sorts, viz. (a) Double or multicellular
acrospores of rounded short cylindrical form, previously taken to be an
independent species (Macrosporium Sarcinula, Berk.). Each such com-
pound spore appears as a rule singly on its sporophore. (<£) Conical pear-
shaped likewise compound spores appearing in series, often in branching
series. This was also formerly described as an independent species of
Alternaria (Nees ab Esenb.). (c) A small form of acrospore recorded by
Bauke, but not, according to de Bary, Cladosporium herbarum (Link),
which, though placed in genetic connection with Pleospora herbarum by
Tulasne, does not belong here. In the third category there are pycno-
spores formed in pycnids interstitially arising on mycelial hyphae. The
pycnids consist of a wall of several layers, from the inner surface of

ASCOMYCETES

375

which there converge series of cells producing successively (terminally
and laterally) pycnospores. These are about twice as long as broad, and
very thin-walled, but surrounded by a hyaline gummy substance. Not
only are all these forms on record, but the mycele shows a tendency to
pass into a resting state, and single cells or groups of cells becom-
ing detached add to the means of propagation. There is some
contradiction involved in the accounts of the occurrence of some of

FIG. 309. — Claviceps purpurea Tul. Longitudinal section of portion of sclerote, m, in Sphacelia
stage, producing conidiospores, c (much magnified). (After Tulasne.)

these forms and the order of their succession given by Bauke and by
Gibelli and Griffini, and further research may be expected to throw
light on the matters in dispute, as also on the question whether or not we
have here one species very rich in spore-forms or two species resembling
each other, but each less rich in forms.

13. CLAVICEPS (Tul.). — The peritheces of Claviceps purpurea (Tul.)
appear as it were in a kind of capitulum (immersed in the same stroma),

376

FUNGI

FIG. 310. — Ear of rye with two
mature sclerotes (ergot) of
Claviceps purpurea> (natural
size). (After Luerssen.)

borne on the summit of a stalk arising from a
sclerote (the well-known ergot of grasses) ; the
ascospores are filamentous in form, and on
germinating produce hyphae at several points.
When this takes place under suitable circum-
stances on the pistil of grasses, the tubes enter,
and, besides penetrating the tissue, form at
length a white hymenium on the surface. This
hymenium consists of numerous cylindrical ste-
rigmata, which bear acrospores at their apices.
(This stage was described by Leveille by the
name of Sphacelia.) These are given off in
drops of a sugary juice which oozes out be-
tween the flower-leaves in which the pistil lies.
This juice, ' honey-dew,' is eaten greedily by
insects, which doubtless eat the acrospores with
it. These propagate the Sphacelia state. At
the base of this acrospore-forming body the
formation of the sclerote proceeds, and it ulti-
mately replaces the ovary, emerging from the
flower of the grass with its base seated on the
floral receptacle. It gives rise in turn to the
sporocarp again.

The allied genera Cordyceps (Fr.) and
Epichloe (Fr.) agree with Claviceps in the de-
velopment of the sporocarp.

Besides the above distinctly marked types,,
the origin of the sporocarp and the life-history
of a considerable number of other forms have
been more or less completely investigated. It
would be entirely beyond the proportions of
the present book to enter into a description
of these, and a discussion of the controversies
that are bound up with the accounts of the
multitude of incompletely known forms. The
citation of the literature at the end of this
section will guide the student to original papers,
but he may also be referred here, as in so many
other cases of difficulty, to de Bary's ' Compara-
tive Morphology and Biology of Fungi,' &c.,
1887, as containing ah exhaustive and critical
treatment of these more or less obscure forms.

ASCOMYCETES

377

He will find there also more information on the development of
the sporocarps (both discocarpous and pyrenocarpous) of the types

FIG. 311. — Claviceps purpurea Tul. A, sclerote which has produced seven stromata.^ fB,
upper portion of a stroma in longitudinal section, cp, peritheces. C, longitudinal section
of perithece. cp, ostiole ; s/i, cortical tissue ; hy, inner tissue of stroma. D, ascus isolated.
sp, ascospores issuing. (A, natural size, B slightly, C and D highly magnified.) (After
Tulasne.)

quoted than it is possible to give in this place without burdening the
section beyond proportion with matter of no striking morphological
significance.

HOMOLOGIES OF THE ORGANS.

De Bary, the founder of the system of classification of fungi adopted
in the present book, calls attention to the striking parallelism between
Ascomycetous forms on the one hand and the Mucorini, Peronosporeae,
and Saprolegnieae on the other. From the oosperms and the spores of
the sporocarps there -arises a thallus which closes its development with
the formation of sexual organs and the oosperm and sporocarp resulting
from their union. In many cases the life-history is confined to this ;
for example, from the Phycomycetes, Pythium vexans, &c. ; from the

378 FUNGI

Ascomycetes, Eremascus, Pyronema, and Ascobolus. In most cases,
however, there intervenes the formation of non-sexual spores which may
be in a species all of one sort, e.g., Erysiphe, Peronospora ; or of several
sorts ; and such spores are, moreover, in many cases exceedingly alike.
Eremascus might almost belong to the Mucorini (Piptocephalideae),
while on the other hand it is not wanting in the essential attributes of
an Ascomycete. In the form of its sexual organs it completely resembles
Penicillium, Gymnoascus, Eurotium, &c. Again, great agreement is to
be recognised between the thallus, spores, and sexual organs of the
Erysipheae (Podosphaera especially) and those of the Peronosporeae.
The resemblance ceases with the farther development of the results of
sexual union, and at this point the groups diverge from the point of
contact of Eremascus and Podosphaera with the Mucorini and Perono-
sporeae. Of course the envelope-apparatus of the asci is not included in
any comparison, as being of purely secondary importance ; and since such
envelope is actually wanting in Eremascusx, the case is made the clearer.
It is also pointed out that though the oogones of the Peronosporeae have
no envelope, it is by no means impossible that such may be found, while
the zygosperms of Mucorini, as has been shown, are sometimes provided
with an envelope. On such evident grounds as these, cited from de
Bary ('Comp. Morph. and Biol. of Fungi,' p. 232), who enters minutely
into the matter (as well as the subject of the sexuality of the Ascomy-
<?etes), the relationship of these groups with each other is abundantly
established.

DOUBTFUL ASCOMYCETES.

i. LABOULBENIE^E. — The Laboulbenieae are a small assemblage of
remarkable parasites on insects, attacking mostly water-beetles, but also
other insects, including the house-fly. They possess no mycele, and
occur fixed on the chitin of the insect attacked by means of a short
process which serves as a haustorium, if that name may be applied to it.
Above this rises a stalk consisting usually of two cells, one above the
other, bearing at the summit a simple perithece and a few lateral hairs
(the appendage] composed of seriated cells sometimes having minute
round swellings at their apices. Before the complete development of the
perithece has been reached, there is emitted from its summit a short fine
process, which may be a trichogyne ; and according to Karsten (Stigma-
tomyces, Karst.) the minute round swellings on the hairs become free and
attach themselves to the trichogyne. Doubt, however, has been cast
upon the accuracy of this observation by the investigation of Peyritsch,
who also attaches no great value to the suggestion that the so-called

ASCOMYCETES

379

trichogyne is fertilised by the contact with it of one of the young hairs.
The perithece contains a number of asci, and these eight or twelve double
ascospores. The ripe double ascospore attaches itself to a fresh host by
one of its ends, and develops into the new plant.

FIG. 312. — A : b — h, Stiginatomyces Bacri Peyr. (St. Musca Karsten). A, optical longi-
tudinal section of ripe specimen with organ of attachment at base ; the asci are seen
through wall of perithece. a, everywhere the appendage ; />, an isolated ascus with spores ;
• c— h, stages of development of perithece and appendage in order of letters. £, Laboiil-
benia JJagellata Peyr. «, the appendage. (A, c, g, h X 350 ; b, d, e,f x 450 ; B x 125.)
(After Peyritsch.)

2. EXOASCUS (Fiickel). — The species of Exoascus mostly attack
fruits, and set up in them sometimes conspicuous deformities. While
some of them possess a mycele which penetrates the parenchyme of the
fruit, &c. (e.g. E. Pruni, Fckl., E. deformans, Fckl.), others extend no
farther than between the cuticle and the epiderm-cells. In the former
•case the terminal cells of the hyphae which emerge from the surface

FUNGI

become asci. In the latter case either certain cells become asci while
others remain sterile or the whole body of hyphae form asci. In E.
alnitorquus (Sadeb.) these asci havjs a pedicel-cell ; in E. aureus (Sadeb.)
there is nothing but asci left at maturity. When the ascospores ger-
minate they give rise to a yeast-like sprouting.

3. SACCHAROMYCES (Meyen). — The species of Saccharomyces occur
in fermenting substances, and are well known from theirpower of convert-
ing sugar into alcohol and carbonic acid. Among the familiar species

are S. cerevisiae (Meyen)
(ordinary yeast), S. el-
lipsoideus (Reess), S.
Pastorianus (Reess), al-
coholic ferments which
are apparently mere form-
species. With these
should be placed S. My-
coderma of Reess, and
Chalara Mycoderma of
Cienkowski ; and the
'thrush' fungus S. albi-
cans (Reess), which lives
parasitically on the mu-
cous membrane of the
human digestive organs,
but is also capable of ex-
citing a feeble alcoholic
fermentation in sugar
solutions. With the ex-
ception of the last-men-
tioned forms in which
a, single cell hyphae occur, the species
of Saccharomyces are
unicellular fungi which
increase by sprouting.
The cells, in which a nucleus has not been demonstrated, are round or
oval in . form, and the sprouting takes place in the form of a pro-
tuberance, which gradually swells and becomes constricted and finally
cut off by a wall at the point of origin. These new cells either separate
at once, or chains or groups remain united as they have been formed!
When such cells are cultivated, on the cut surface of a potato for
example, certain cells may form asci, each containing two to four
ascospores. These are at once capable of germination, which takes-

F'iG. 313. — Saccharomyces cerevisice Meyen.
of beer-yeast ; b, c, stages of sprouting ; d, colony of sprout-
cells ; e, cell with four ascospores ; f, one with two ; g, group
of ascospores with one sprouting ; A, further development of
a similar group (h x 750, the others much more), (e — h
after Reess.)

ASCOMYCETES 381

place by the sprouting process described, though they may retain the
power of germinating for a longer period.

This cell-increase by sprouting is, as has been seen, by no means
confined to Saccharomyces, but occurs in other groups of fungi (e.g.
Mucor), and the special character which entitles them to this place in
the classification of fungi is the production of asci, which they share
only with the Ascomycetes. They may therefore be regarded as much
degraded Ascomycetous forms — the other alternative, that they are early
forms from which typical Ascomycetes have developed, being disposed
of by the establishment of the connection of this great group with the
Phycomycetes as already described.

LITERATURE.

Barenetski— Entwickel. d. Gymnoascus Reessii (Bot. Zeit., 1872). ,

De Bary— Ueber d. Fruchtentwickel. d. Ascomyceten (Leipzig, 1863).

De Bary — Beitr. zur Morph. u. Physiol. d. Pilze, iii., 1870.

De Bary — Exoascus Pruni (Beitr., i.).

De Bary— Ueber einige Sclerotinien, &c. (Bot. Zeit., 1886).

Bauke — Zur Entwickelungsgesch. d. Ascomyceten (Bot. Zeit., 1877).

Bauke — Beitr. zur Kenntniss d. Pycniden (Nova Acta Leop., xxxviii., 1876).

Borzl— Studii sulla sessualita degli Ascomicete (N. Giorn. Bot. Ital., x., 1878).

Brefeld— Botan. Untersuch., ii. and iv. ; compare also v.

Brefeld — Mucor racemosus und Hefe (Flora, 1873).

Brefeld — Ueber Gahrung (Thiel's Landwirthsch. Jahrb., 1875, 1876).

Cienkowski — Die Pilze der Kahmhaut (Melanges Biol. Acad. St. Petersb., viii.).

Cornu— Reproduction des Ascomycetes (Ann. Sc. Nat., 6 ser., Tom. u).

Currey — On the Fructification of certain Sphoeriaceous Fungi (Phil. Trans. Roy.

Soc., 1858).

Eidam— Beitr. zur Kenntniss d. Gymnoasceen (Cohn's Beitr., iii.).
Eidam — Zur Kenntniss d. Entwickel. d. Ascomyceten (ibid.).
Eidam— Ueber Pycniden (Bot. Zeit., 1877).
•Engel — Les ferments alcooliques, 1872.

Fisch — Zur Entwickelungsgesch. einiger Ascomyceten (Bot. Zeit., 1872).
Fiiisting — De nonnullis Apothecii Lichenum evolvendi rationibus (Diss. inaug.

Berol., 1865).

Fiiisting — Zur Entwickelungsgesch. d. Pyrenomyceten (Bot. Zeit., 1867, 1868).
Fiiisting — Zur Entwickelungsgesch. Lichenen (ibid., 1868).

Gibelli — Sugli org. reprod. del gen. Verrucaria (Mem. Soc. Ital. di Scienc. Nat., i.).
Gibelli e Griffini — Sul polimorfismo della Pleospora herbarum (Arch. d. Laborat. di

Bot. Crittog. Pavia, i., 1875).

Gilkinet — Recherches sur les Pyrenomycetes (Bull. Acad. Belg., 1874).
Hansen — Oidium lactis, &c. (Medd. fra Carlsberg Laborat., Bd. i.).
Hansen — Untersuch. iiber d. Physiol. u. Morph. d. Alkoholfermente (ibid.).
Hansen— Untersuch. iiber d. Organismen welche sich zu verschiedenen Jahreszeiten

in d. Luft finden, &c. (ibid.).
Hansen — Untersuch. iiber d. Physiol. u. Morph. d. Alkoholgahrungspilze (ibid.,

Bd. ii.).

3S2 FUNGI

Hansen — Bemerk. liber Hefepilze (Allg. Zeitsch. f. Bierbrauerei, &c. , 1883; Bot.

Central bl., xvii.).

Hartig — Wichtige Krankheiten d. Waldbaume, p. 101.
Hartig — Untersuch. aus d. Forstbot. Institut_zu Mi.inch.en, i.
Janczewski — Morphol. d. Ascobolus furfuraceus (Bot. Zeit., 1871).
Karsten — Stigmatomyces (Laboulbeniaceen) in Chemismus der Pflanzenzelle, 1869.
Kihlman — Zur Entwickelungsgesch. d. Ascomyceten (Acta Soc. Sc. Fennicse, xiii.,.

1883).
Krabbe — Entwickel., Sprossung und Theilung einiger Flechtenapothecien (Bot. Zeit.,

1882).
Krabbe — Morphol. u. Entwickelungsgesch. d. Cladoniaceen (Ber. d. D. Botan.

Gesellsch., 1883).

Kiihn — Mittheil. d. Landw. Instituts Halle, i.
Lauder Lindsay — Spermogones and Pycnides of Lichens (Trans. Roy. Soc. Edinb. ,

xxii. ).

Low — Ueber Dematium pullulans (Pringsh. Jahrb., Bd. vi.).
Mattirolo — Sullo sviluppo e sullo sclerozio della Peziza Sclerotiorum Lib. (N. Giorn.

Bot. Ital., xiv.).

Millardet — Mem. Soc. d'Hist. Nat. Strasbourg, vi., 1868 (Myriangium, &c.).
Pasteur — Mem. sur la fermentation alcoolique (Ann. Chim. et Phys., Tom. Iviii.,

1860).

Pasteur — Etudes sur la biere (Paris, 1876).
Peyritsch — Ueber die Laboulbeniaceen, &c. (Sitzber. Wiener Acad., Bd. 64,

Abth. I, 1871 ; Bd. 68, Abth. I, 1873 ; and Bd. 72, Abth. 3, 1875).
Pirotta — Sullo sviluppo della Peziza Fuckeliana (N. Giorn. Bot. Ital., xiii.).
Rathay — Ueber d. Hexenbesen d. Kirschbaume (Sitzber. Wiener Acad., Bd. 83,

Abth. i).

Reess— Botan. Untersuch. liber d. Alkoholgahrungspilze (Leipzig, 1870).
Reess — Zur Kenntniss d. Exoascus d. Kirschbaume (Sitzber. d. Phys. Med.

Gesellsch. 'zu Erlangen, 1882).
Reess— Ueber den Soorpilz (ibid., 1877 and 1878).
Reess — Untersuch. ii. Elaphomyces granulatus (Deutsch. Naturf. u. Aerzte, Strass-

burg, 1885).

Reinke u. Berthold — Die Zersetzung d. Kartoffel durch Pilze (Berlin, 1879).
Schwendener — Ueber d. Entwickelung der Apothecien von Ccenogonium (Flora,

1862).
Schwendener — Ueber d. Apothecia primitus aperta u. d. Entwickel. d. Apothecien

im Allgemeinen (ibid., 1864).

Sorokin — Quelques mots sur PAscomyces polysporus (Ann. Sc. Nat., 6 ser., Tom. iv.).
Stahl — Beitrage zur Entwickelungsgesch. d. Flechten, i. (Leipzig, 1877).
Van Tieghem— Chsetomium (Comptes Rendus, 81).
Van Tieghem — Nouv. observ. sur le developpement du fruit, &c., des Ascomygetes

(Bull. Soc. Bot. France, xxiii., 1876). (See also Bot. Zeit. same year.)
Van Tieghem — Sur le developpement du fruit des Ascodesmis (ibid. ).
Van Tieghem — Nouv. observ. sur le developpement du perithece des Choetomium

(ibid.).

Van Tieghem — Sur le developpement de quelques Ascomycetes (ibid., xxiv.).
Van Tieghem— Monascus, genre nouveau de 1'ordre des Ascomycetes (Bull. Soc.

Bot. France, 1884).
Tulasne— Fungi hypogaei (Paris, 1851).

ASCOMYCETES 383

Tulasne — Selecta Fungorum Carpologia, i.-iii. (Paris, 1861-65).

Tulasne — Rech. sur 1'organisation des Onygena (Ann. Sc. Nat., 3 ser., Tom. i.).

Tulasne— Note sur 1'appareil reproducteur des Lichens et des Champignons (ibid.,.

3 ser., Tom. xv.).

Tulasne— Mem. pour serv. a 1'hist. organograph. et physiol. des Lichens (ibid., 3,

ser. , Tom. xvii. ).

Tulasne — -Discomycetes (ibid., 3 ser., Tom. xx.).
Tulasne — Mem. sur 1'Ergot des Glumacees (ibid.}.
Tulasne — Note sur 1'appareil reprod. des Hypoxylees et des Pyrenomycetes (ibid.,

4 ser., Tom. v. ).

Tulasne — Nouv. observ. sur les Erysiphes (ibid., 4 ser., Tom. i.). (See also Bot. Zeit.,.

18530

Tulasne — Note sur les Isaria et les Sphaeria entomogenes (ibid., 4 ser., Tom. viii.).
Tulasne — De quelques Spherics fongicoles (ibid., 4 ser., Tom. xiii.).
Tulasne — Note sur les phenomenes de copulation d. 1. Champignons (ibid., 5 ser.,.

Tom. v.).

Tulasne — Super Friesiano Taphrinarum genere (ibid.}.
Vittadini — Monographia Tuberacearum (Mediolani, 1831).
Vogel — Gymnoascus uncinatus (Bot. Centralblatt, xxix. ).
Wilhelm — Beitr. zur Kenntniss d. Pilzgattung Aspergillus (Diss. Berl., 1877).
Woronin — Entwickelungsgesch. d. Ascobolus pulcherrimus und einiger Pezizen

(Beitr. zur Morph. u. Physiol. d. Pilze, ii.),
Woronin — Sphaeria Lemaneae, Sordaria, &c. (ibid., iii. ).
Zopf — Zur Entwickelungsgesch. d. Ascomyceten (Chaetomium) (Nova Acta Leop.».

xlii.).
Zopf — Die Conidienfriichte von Fumago (ibid., xl.).

Class XXI.— Uredineae.

The Uredineae are a class of parasites on flowering plants and ferns*.
They resemble the Ascomycetes in many points, as will be seen from
this short account of them. The mycele is septate and much branched,
follows the intercellular spaces of the host-plants, and penetrates the.
cells themselves by means of short branches.

Puccinia graminis (Pers.) may be taken as a type of the course of
development followed by some of the forms. Owing to the change of
host involved in the course of development of this and other forms, and
to the different appearances presented by succeeding stages of the
organism, it was formerly supposed that these stages constituted distinct
fungi. Thus no less than three form-genera (^Ecidium, Pers., Uredo,
Pers., and Puccinia, Pers.) were established to denote the stages of the
life-cycle of Puccinia graminis, the well-known com mildew. The
sporocarp (^Ecidium) is formed in spring on the barberry. In its

FUNGI

FIG. 314. — A, diagrammatic transverse section of
barberry leaf with secidia, a, b, and antherids.
s (slightly magnified). B, uredospores, 11, and
teleutospore, t. C, germinating uredospore
(S and C x 390). D, teleutospores. £, germi-
nating teleutospore : promycele, /, and spo-
rids, sp ( x 400). (A , £, D, and E of Pnccinia
^graminis, C of P. straminis Fckl., F teleuto-
spore of A coronata Cord., X 300). G, teleuto-
spore of Phragmidium incrassatum Link,
(x 300). -04, .F and G, after Luerssen ; B — D,
after de Bary ; E, after Tulasne.)

earliest stage it appears to consist
of a densely interwoven mass of
hyphse situated in the subepi-
dermal parenchyme of the leaf.
This gradually increases in bulk
and displaces the surrounding
tissue. As it grows the hyphse in-
crease in size, and the shape of
the whole becomes more definitely
spherical. Within the base of this
sphere the hymenium is developed,
and consists of a continuous layer
of club-shaped basids, from the sum-
mit of each of which is produced in
basipetal succession a single series
of (Ztidiospores. Enclosing the
sporal mass is a single layer of
pseudo-parenchymatous cells aris-
ing from the margin of the hyme-
nium, and arching over the top of
the spores. The cells composing
the envelope are larger than the
spores, and possess thicker walls,
while their clearer contents contrast
with the orange-coloured spores.
The enlargement of the whole
body increases until the epiderm is
ruptured, while the tissues of the
host are pushed aside and com-
pressed. After the rupture of the
epiderm the envelope bursts at the
apex, and curves back, forming the
lip of a cup-shaped body ; the
sporal mass is farther elevated and
the spores escape. These sporo-
carps are situated on the under sur-
face of the leaf, but accompanying
them on the upper surface there are
to be found numerous flask-shaped
antherids containing pollinoids
produced at the apices of ste-
rigmata, and in all points recalling

UKEDINE&

385

those already described in Collema. They are orange-coloured like the
sporocarps, and the pollinoids have never been known to germinate.
No corresponding female sexual organ occurs in any Uredine, though
the early stages of the development of the sporocarp are not sufficiently
known. No such body as Woronin's hypha in Xylaria, for example, has
ever been observed in the Uredineae, and the only suggestion of a female
sexual organ is to be found in the occasional occurrence in some
Uredines of short obtuse hyphae, projecting through the stomates of the
host like the trichogynes of Polystigma. These may be traced, it is true,
to young aecidia, but there may well be nothing more in the suggestion
than the mere protrusion of mycelial hyphae, since observations connecting
such filaments with an act of fertilisation are
wholly wanting. Massee ('Annals of Botany,'
1888, p. 47) has recently published an ac-
count of observations of a supposed sexual
process in Uredineae, involving the fertilisa-
tion of a carpogone by an antheridial branch ;
but the subject stands in great need of farther
investigation.

The spores from the ripe sporocarp (aci-
diospores) germinate only on the leaves
or stems of grasses, and the germ-tubes
entering by way of the stomates give rise to
myceles, which attack the tissues of the host.
In the course of a week or more, cushion-
like masses of mycelial hyphae situated be-
neath the epiderm give rise to erect basids,
each of which bears a red uredospore (Uredo)
at the apex. On the rupture of the epiderm
the uredospores escape, and these alighting on
grass plants germinate, again enter by way of the stomates, and renew the
same generation. This process may and does go on indefinitely, and
thus much damage is annually caused by the attack of this fungus on
the corn crop.

Later on there are developed' on the same mycele, first side by side
with the uredospores, then gradually replacing them altogether, two-celled
spores called teleutospores, and with their production the development of
the fungus ceases for a period. In this condition the winter is passed.
With spring they germinate, each of the two cells of the teleutospore
(Puccinia) giving rise to a short promycele, the terminal cells of which
bear on slender stalks a single sporid apiece. These sporids germinate
in turn on the leaves of the barberry, the germ-tubes piercing the epi-

c c

FIG. 315.— Puccinia graininrs
Pers. t teleutospore ; it, uredo-
spores ( x 390). (After Sachs.)

386 FUNGI

derm, and giving rise within to the mycele which ultimately bears the
sporocarps and antherids.

Gymnosporangium (DC.) represents another type of the course of
development in Uredineae. The sporocarps (corresponding to aecidia,
but here denoted by the form-genus Roestelia, Reb.) appear in summer
on the leaves and fruits of Pomeae. No uredospores are formed.
The next generation (teleutospores) is produced in spring on juniper in
odd-shaped mucilaginous brown or yellow masses. Promyceles are formed
which bear sporids, and these again set up on the leaves, &c., of Pomese
the sporocarp generation.

A farther reduced type is to be found in Endophyllum (Lev.). In
this case the germ-tube of the spores of the sporocarp (aecidiospores)
becomes a promycele, and, dividing up into several cells, each of these
bears at the end of a sterigma a single sporid. The sporid on germi-
nating renews the sporocarp generation.

Two cases of exceptional structure may be noted. In Phragmidium
(Link) the sporocarps have no proper envelope, the place of the wall
being taken by a circle of club-shaped paraphyses surrounding the
margin of the hymenia. On the other hand the uredospores of Me-
lainpsora populina (Jacq.) and of Cronartium (Pers.) are enclosed in
an envelope resembling that of the sporocarp. The development of
the paraphyses in the one case and of the envelope in the other requires
investigation.

Besides the sporocarp-forming Uredineae there is another group
known as the tremelloid Uredinece, which do not possess a sporocarp
generation. These are not to be confounded with those Uredineae in
which presumably from want of investigation the sporocarps are un-
known. The course of development of the tremelloid Uredineae is per-
fectly well known in a number of cases (Leptopuccinieae and Leptochry-
somyxa, de By.), and consists of a teleutospore-bearing generation with
commonly softer and more gelatinous spore-membranes. These teleuto-
spores germinate as a rule at maturity and not after a period of rest.
The sporids formed on the promycele produce a mycele which again
bears teleutospores. Leptopuccinia malvacearum (Schroet), L. Dianthi
(Schroet), &c., bear the same relation in appearance, &c., to Puccinia
as Leptochrysomyxa Abietis (Ung.) bears to Chrysomyxa (Ung.), the
species of which form sporocarps, uredospores, and teleutospores.

Enough has been said in this brief account to indicate a probable
connection of the Uredineae with the Ascomycetes through their
sporocarps. Those .forms — the tremelloid Uredineae — in which the
sporocarp generation may be presumed to have been lost, sufficiently
resemble the complete types to be necessarily bound up with them ;

UREDINE^E 387

while on the other hand, as will be seen, they furnish a valuable link
with the next class.

LITERATURE.

De Bary — Untersuch. iiber die Brandpilze (Berlin, 1853).
De Bary — Rech. sur le developpement de quelques Champignons parasites (Ann. Sc.

Nat., ser. 4, xx.).

De Bary — Ueber Cseoma pinitorquum (Monatsber. Berl. Akad., 1863).
De Bary- Neue Untersuch. iiber d. Uredineen (ibid., 1865, 1866).
De Bary — Ueber d. Krebs u. d. Hexenbesen d. Weisstanne (Bot. Zeit., 1867).
De Bary— /Ecidium abietinum (ibid., 1879).
Dietel — Beitr. z. Morph. u. Biol. d. Uredineae (Bot. Centralblatt, xxxii., 1887, p.

54; ibid., 1888, No. 33).
Farlow— The Gymnosporangia or Cedar Apples of the United States (Mem. Boston

Soc. Nat. Hist., 1880).

R. Hartig — Wichtige Krankheiten der Waldbaume (Berlin, 1874).
R. Hartig — Lehrbuch der Baumkrankheiten (Berlin, 1882).

Leveille— Sur la disposition methodique des Uredinees (Ann. Sc. Nat., ser. 3, viii.).
Oersted- Orn Sygdomme hos Planterne, &c. (Kjobenhavn, 1863).
Oersted — On Podisoma and Roestelia (Oversigt k. Danske Vidensk. Selskab.

Forhandl., 1866 ; and K. Danske Vidensk. Selskab. Skrifter, ser. 5, vii. ).
Parker— On the Morphology of Ravenelia gUndulaeformis (Proc. Amer. Acad. Sc.

and Arts, 1886).
Rathay— Untersuch. iiber d. Spermogonien d. Rostpilze (Denkschr. d. \Vien. Akad.,

1883, Bd. xlvi.).
M. Reess —Die Rostpilzfonnen d. deutsch. Coniferen (Abhandl. Nat. Gesellsch.

zu Halle, Bd. xi.).
Schroter — Die Brand- u. Rostpilze Schlesiens (Abhandl. Schles. Ges. vaterland.

Cultur, 1869 [1872]).
Schroter— Entwickelungsges. einiger Rostpilze (Cohn, Beitr. i., Heft 3; ibid., hi.,

Heft i).

Schroter — Ueber einige amerikanische Uredineen (Hedwigia, 1875).
Schroter — Beobacht. iiber d. Zusammengehorigkeit von ^Ecidium Euphorbke u.

Uromyces Pisi (ibid., 1875).
Tulasne— Mem. sur les Ust'laginees et les Uredinees (Ann. Sc. Nat., ser. 3, vii. ;

ibid., ser. 4, ii.).
Ward— Researches on the Life-history of Hemileia vastatrix (Linn. Soc. Journ. Bot.,

xix.).
Ward — On the Morphology of Hemileia vastatrix (Quart. Journ. Micr. Sc., N.S.,

xxii., 1882).
R. Wolff — /Ecidium pini u. seine Zusammenhang mil Coleosporium Senecionis Lev.

(Festschrift, Riga, 1876).

In the above papers will be found references to older literature and farther
memoirs on the group. For a systematic account the student is specially referred to
Winter's Die Pilze Deutschlands, Oesterreichs und der Schweiz, in the new edition
of Rabenhorst's Kryptogamenflora von Deutschland, &c. ; and to Plo \\ light's British
Uredineaeand Ustilagineee (London, 1889).

C c 2

388 FUNGI

Class XXII.— Basidiomycetes.

The Basidiomycetes are a large class comprising forms of the utmost
diversity in appearance, mostly saprophytes living on humus, rotten wood,
or the old wood and the bark of trees. A small number are parasites.
They all agree in the production of spores (basidiosports) acrogenously
on basids, which are club-shaped and disposed as a rule parallel to each
other, thus forming hymenia. The spores produced on one basid are
two or four in number, more rarely eight, though divergences from these
numbers occur. They vary in shape, but consist, except in some Tremel-
lineae, of a single cell. Among the basids there commonly occur sterile
hyphal branches — paraphyses. Besides these spores thus borne on
definite hymenia there are also others produced more or less inde-
finitely on the myceles of certain members of the group, and their
character will be described below. The Basidiomycetes are divided
into two sub-classes, the HYMENOMYCETES with gymnocarpous, and the
GASTEROMYCETES with angiocarpous fructification.

Sub-class 1. — Hymenomycetes.

The Hymenomycetes are characterised by the possession of a
hymenium on the free exposed surface of the compound structure which
bears it — the sporophore. The forms embraced in this sub-class range
from very simple to highly complex structures, the latter being repre-

FIG. 316. — Tremella mesenterica. Retz. (natural size). (After Tulasne.)

sented by such types as the common mushroom and the like — in short
those fungi to which the name is popularly applied.

EXOBASIDIUM VACCINII (Woron.) may be taken as the simplest type.
Its mycele is parasitic on the leaves and stems of Vaccinium vitis-idaea,

BA S IDIOM YCE TES

389

and forms on the surface a hymenium of club-shaped basids each of
which produces four basidiospores. The spores divide at maturity trans-
versely into four cells, only the two end cells of which germinate, doubt-
less at the expense of the contents of the remaining two. The germ-
tubes penetrate the epiderm of the leaf of the host, and a new mycele is
formed which again bears basids. If, however, germination takes place
elsewhere than on the proper host-plant, and conditions for the vegeta-
tion of the fungus be otherwise favour-
able, the germ-tube begins to sprout in-
definitely by means of elongated sprout-
cells, giving rise to others only at the ends.
This condition has been maintained in nu-
trient solutions for a considerable time, but
the sprout-cells have never been observed
actually to give rise to a new mycele like
the one produced by the basidiospores.

The TREMELLINE^E (Tremella, Dill,
Exidia, Fr.) present another simple type.
They are gelatinous fungi of not very
definite form, commonly of wavy outline,
and are saprophytic on old and dead
wood. The hymenia are formed on
the surface of the gelatinous mass. The
basids vary in appearance, and are usually-
provided with fine elongated sterigmata
and reniform spores. Certain forms such
as Sebacina (Tul.) and Hypochnus (Fr.)
do not possess gelatinous membranes. The
course of development is much the same
as in Exobasidium. The germinating
basidiospore gives rise under ordinary con-
ditions to the compound sporophore
again. Under other conditions, it has been
observed in Dacryomyces, the germ-tubes
do not grow to any great length, but produce
secondary spores, or they form sprout-cells.

The basidiospores of the same form divide transversely at maturity, usually
into four cells, each of which may germinate. It should be added that
on germination these secondary spores give rise to myceles. The hyphae
of such myceles, moreover, as well as those proceeding from basidiospores,
sometimes give rise to tufts of rod-like cells, which in turn produce
myceles. Similar phenomena have been observed in other Tremellinege.

FIG. 317. — Exidia spiculosa Sommerf.
Longitudinal section of portion of
hymenium (much magnified). s,
spores ; b, basids : h, hyphae of
thallus. (After Tulasne.)

390

FUNGi

It is manifest therefore that in these simple types we have repeated
very much the same order of things as in the tremelloid Uredinese. It is
perhaps most striking in the case of Exobasidium, from which the transi-
tion is easy to the Tremellineae. The layer of basids and basidiospores may
be compared with the layer of teleutospores, while the transverse division

FIG. 318. — Coprinus stercorarius Fr. A, B, and C, germinating spore in successive stages. D
portion of mycele, *«, with five early stages of development of fungus. E and F, further stages.
(7, longitudinal section through germinating sclerote, s, with young fungus still within volva, t>.
//, fully developed fungus with sclerote, s, and rhizoids, r. (A—C x 300, D x 200, E x 120,
F x 50, G and H natural size.) (After Brefeld.)

of the basidiospores into four cells, two of which germinate, heightens the
resemblance. Farther the production of secondary spores on the short
germ-tubes of basidiospores recalls the formation of sporids on the

BASIDIOMYCETES

.391

promyceles from teleutospores.
From the Tremellineae another
easy step leads us on to the
Thelephoreae, and it may be
borne in mind in this connec-
tion that certain Tremellinese,
as mentioned above, do not
possess gelatinous membranes.

The THELEPHOREAE (Corti-
cium, Pers.) may be shortly
described as recalling in point
of simplicity of structure the
teleutospore-layer of Uredineae,
while they approach very closely
the club-shaped Hymenomy-
cetes such as the Clavariese, in
which the hymenium is dis-
posed on the outer surface of
erect club shaped cylindrical
and often much-branched com-
pound sporophores. Through
a series of intermediate forms,
the completeness of which may
be recognised from a systematic
study of the group, we proceed
to the more perfect types of
Hymenomycetes which possess
sporophores of more complex
structure.

In the higher forms of
Hymenomycetes, the sporo-
phore consists of a cap ex pileus
borne on the summit of a stalk
or stipe. The mycele com-
monly vegetates in a soil rich
in humus or on old wood or
the like, and though usually of
loose filamentous texture it is in

FIG. -$\<).—Agaricus mellens L., in diffe-
rent stages of development on branched
rhizomorph-strands. The upper portion
of rhizomorph represents that formerly
known as RhizomorpHa fragilis Roth,
while the lower strap-shaped portion is
var. subcor tic alls. (After Hartig.)

392

FUNGI

certain instances of more compact character. Such are the sderotes which
are resting states of Coprinus stercorarius (Fr.) (fig. 318), and the rhizo-
viorphs of Agaricus melleus (L.) (fig. 319), composed of root-like
branched strands of rnycelial hyphae, parasitic on the pine. The rhizo-
morphs are simply sclerotes with growing-points. From the mycele, of
^yhatever character it be, there arises the compound sporophore by the
continued apical or marginal growth of a bundle of hyphae. It is not
certain, but it may very well be, that intercalary growth also, in some

FIG. 320. — Agaricus campestris L. The common mushroom (natural size). Stages of development
from a to e ; b and c in section. (After Luerssen.)

cases at least, assists in the development. The hymenial surface, which
is commonly situated on the under surface of the cap or pileus, is
characterised in different genera by being spread over teeth-like projec-
tions (Hydnum, L.), radial plates in the numerous species of Agaricus
(L.), concentric plates in the small genus Cyclomyces (Kze.), reticulated
folds or pores (Polyporus, Mich. Boletus, L.) ; such typical characters
being united by a wealth of intermediate forms. As a rule these pro-
jections are very symmetrical and of regular occurrence, and on them the
chief generic characters are based in the classification of the group ;

BA SIDIOM YCE TES

393

FIG. 321. — Cogrinus stercorarius Fr. Longi-
tudinal section of the end of a gill in com-
plete spore-bearing. t, trama; /, sterile
palisade cells ; b, basids with spores ; e,
cystids (x 300). (After Brefeld.)

they are termed ^///y or lamella in the AGARICINI,/W^ or tubuli in POLY-
PORE^E, and teeth in the HYDNE^E. In many of the forms the hymenium
is exposed from the first ; in a series
of others a membrane (velum partiale]
connects the edge of the pileus all
round with the stalk, and on its rupture
by the extension of the pileus, part of it
is left attached to the stalk, when it is
termed the annulus or ring (fig. 320),
though this does not occur in all cases.
In a third series a membrane (velum
universale or volvci} (fig. 31 8) encloses
the whole sporophore, pileus and
stalk alike, and in the species be-
longing to Amanita, a sub-genus of
Agaricus, both velum universale and
velum partiale are present. In these
latter cases, therefore, in which a
membrane is present,
the sporophore differs
from the truly gymno-
carpous forms. The de-
velopment of Amanita
is especially noteworthy,
since the gills are not
developed on the free
inner surface of the
pileus, but during an
early condition from
tissue common to both
stalk and pileus.

Immediately beneath
the hymenium is a layer
of tissue called the sub-
hy menial layer, distin-
guished from the rest of
the tissue of the sporo-
phore by the greater
density of the ramifica-
tions of the hyphae and

by the more abundant FIG. 322. — Polyponis igniarhis Fr. Transverse section of the

under surface, h, the plexus of hyphae forming the walls be-
Contents. tween the pores ; s, the hymenium ( x 270). (After Luerssen.)

594

FUNGI

The trama is that portion of the projection which bears the subhyme-
nial layer, and consists of hyphae running parallel to the surface from
the insertion of the projection to its margin, which in many cases is un-
covered by the hymenium.

The hymenium itself consists of parallel rows of club-shaped basids
surmounted bysterigmata and basidiospores. The basids are the termi-
nations of the subhymenial hyphae, but the latter also frequently end
in sterile cells, which are termed paraphyses, from the fact that they
stand in the same relation to the basids as the paraphyses do to asci.
Large inflated cells, often of relatively great dimensions, called cystids,

FIG. 323. — Polyporus igniarius Fr. Upper surface (half natural size). (After Luerssen.)

are frequently found emerging from the hy menial surface (fig. 321). They
are very variable in form, club shaped, flask-shaped, cylindrical; pointed,
hooked, or knob-shaped at the tip. They may be regarded as merely
prominent hymenial hairs with the probable function of protecting the
basids, or of parting the appressed lamellae. They have been the
subject of much idle speculation, and among other erroneous views they
have been regarded as male organs.

In the sporophores of many Agaricini, notably of Lactarius (Fr.),
latidferous hyphce occur, which yield considerable quantities of milky,
generally acrid, juice when the tissue is bruised.

BA S IDIOM YCE TES

395

Sub-class 2. — Gasteromycetes.

The Gasteromycetes very closely resemble the Hymenomycetes in
the essential points of the structure of the basids. At all events the
agreement is close in this respect between the higher Hymenomycetes
with cap and stalk, and the Hymenogastreae, a section of the Gastero-
mycetes ; while other subordinate sections, such as the Lycoperdaceae
and Phalloideae, diverge from the Hymenogastreae only in minor points,
as, it was seen, the lower Hymenomycetes do from the higher forms.
The possession of a trama with a hymenial layer on either side of it may
be here noted. In the external conformation, however, of the members
of the group, a great variety is displayed, and, but for the existence of
numerous intermediate forms, the group would
appear to lack coherence in this respect, so great
is the range of variation.

The mycele is very frequently in the form of
root-like strands, though there is no constancy
in this respect, and the simple filamentous
mycele occurs abundantly. The compound
sporophores frequently grow to a great size in
some of the sections, but the character which
unites the whole is the possession of an invest-
ing membrane, the peridium, within which, and
springing from it, are plates of tissue dividing the
interior into chambers where the hymenium is
produced.

At the outset there may be noted the remarkable genus Gautieria
(Vitt.), which has no peridium. The peripheral chambers are therefore
exposed on the free surface. The peridia of other forms vary consider-
ably in thickness and other characters, and a tendency exists towards
excessive thickening in the basal region, which develops outwards,
forming a stalk in some instances, e.g. Lycoperdon (Tourn.) ; or inwards,
in which case either a cushion-like body is produced, e.g. Hymeno-
gaster (Vitt.), or a central column, e.g. Phalloideae. The whole cham-
bered structure is termed the glebe.

The HYMENOGASTREAE may be regarded as an assemblage of the
simplest forms of Gasteromycetes, possessing usually the simple structure
indicated, but including among its members Gautieria without aperidium,
and Secotium (Kze.), a genus with a central column traversing the body
of the fungus. These two forms but heighten the resemblance which it
lias been remarked exists between the Hy-menogastreae and the Hymeno-

FIG.

324

— A, Octa?>iana

asterosperma Vitt., in sec-
tion ( x 5). (From .Luerssen
after Tulasne.)

396

FUNGI

mycetes, the one being an approach to gymnocarpous forms, and the
other noteworthy in respect of its stalked and pileate appearance.
De Bary, in comparing the groups, says (' Comp. Morph. and Biol,'
P- 337) : 'If we could attribute a decisive value to the habit of the
plants, we should dwell upon the great resemblance between the stalked
Hymenogastreas, like Secotium erythrocephalum (Tul.), and a veiled
Boletus. . . . But among the Polyporese there is a remarkable form
Polyporus volvatus (Pk.), the Polyporus obvallatus (Berk, and Cooke),
which considered by itself must be placed with or close to the Hyme-
nogastreae. 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

FIG. 325. — Batarrea Steveni Fr., longitudinal sections.

a, a younger specimen, but with most of its spores ripe

b, a mature specimen, of which only apex and base are
shown, p and h, the outer, i, the inner peridium ; g,
the glebe (one-third natural size). (After de Bary.)

FIG. 326. — Batarrea Steveni Fr.
Isolated threads of the capillitium
( x 390). (After de Bary.)

covered with the hymenium of a Polyporus on the part next the sub-
stratum, and is sterile on the opposite side.'

In the LYCOPERDACE.E (Puff-balls) the peridia are often developed to
a colossal size, and in structure they agree in the main with the Hyme-
nogastreae. The chief distinction lies in the existence of two kinds of
hyphae in the trama ; slender segmented hyphae with dense protoplasmic
contents, the terminal members of which compose the hymenium, and
stouter hyphae running not only in the trama, but crossing the chambers.
Eventually the slender hyphae and the hymenium disappear, leaving only
the stout hyphae, now called the capillitium, and the masses of spores
between. As examples of the possession of both inner and outer peridium
in this section, there may be cit^d Geaster (Mich.), in which the outer one

BA S IDIOM YCE TES

397

becomes recurved after splitting longitudinally and acquiring a stellate
aspect, and Batarrea (Pers.), which possesses an axile column immedi-
ately beneath the middle of the inner peridium. It develops into a stout
stalk, which raises the closed inner peridium on its summit and ruptures
the outer one, which now resembles in appearance the velum universale
of Hymenomycetes. In Scleroderma (Pers.) the development of the
glebe is intermediate between Hymenogastreae and Lycoperdaceae.
While the trama is disorganised, and a portion persists as a fine network
together with the masses of spores, it yet forms no true capillitium.
The NIDULARIE/E, though very different in outward aspect from the

FIG. 327. — Crucibiilum vulgare Tul.
•A—C, longitudinal section through
ripening sporophores ; stages of deve-
lopment in order of letters (slightly
magnified). D, ripe sporophore in
which the epiphragm is beginning to
disappear (natural size). (After de
Bary.)

up

FIG. •$-2<&.—Cnicibulum vulgare. Section through upper
part of sporophore of about same age as B in Fig. 327
(more highly magnified), a/, the outer, ij>, the inner
peridium ; rf and of, its hairs ; «, funiculus ; t, the
layer which forms a sheath round it, and belongs to a
peridiolum divided through the middle. (After Sachs.,}

other sections, are yet readily comparable with them. The chambers
of the glebe possess very stout walls, and ultimately become separated
from each other. The wall of the peridium becomes transformed into
a gelatinous substance over the apical region, and on its disappearance
the chambers of the glebe (peridiola) are left exposed in the interior of
the bowl-shaped lower portion of the wall. Free and detached they
resemble comparatively large sporanges. In Crucibulum (Tul.) a thin
white membrane ternied the epiphragm temporarily covers the summit

(ng- 327)-

The PHALLOIDE^: are an assemblage of very remarkable and strange
forms, in which the Basidiomycetes find their highest development.

398

FUNGI

Great variety of external conformation exists within the group, as the
student will at once recognise on viewing such members of it as Phallus
(L.), Hymenophallus (Nees ab Esenb.), Clathrus (Mich.), Ileodictyon
(Tul.), Aseroe (La Bill.), &c.

Specimens of Phallus impudicus (L.) while yet enclosed within the
peridium exhibit the following structure : The peridium consists of an
outer white membrane and an inner white thinner one, and between these
two a thick layer of tissue which has become gelatinous. Immediately
within the inner membrane lies the glebe, situated in the upper capitate
portion, and bounded on its inner surface by a conical membrane

FIG. 329. — Mntittus caninns Fr. Young sporophore.
in, mycele ; stages of development in order of letters
it — y. y, a specimen with ripe spores, but before elonga-
tion of stalk, a, the outer wall ; /, the inner : g, gela-
tinous layer of peridium ; l>, the basal portion ; k, the
cone ; s, the stalk ; gb, the glebe (natural size). (After
de Bary.)

FIG. 330.— A nearly mature specimen of
Phallus impudicus L. before elonga-
tion of stalk, in longitudinal section.
/«, mycele ; a, outer, t, inner wall ; g,
gelatinous layer ; st, stalk ; h, its
cavity filled with mucilage ; t, lower
margin of pileus ; j/, glebe; », the
cup-shaped basal portion ; x, the spot
where the peridium bursts (two-
thirds natural size). (After Sachs.)

belonging to the central axis. This membrane gives off outwards into
the glebe numerous walls arranged honeycomb fashion and dividing
the glebe into compartments. The structure of the glebe itself recalls
that of the Hymenogastreae and Lycoperdacese. Below the glebe, and
surrounding the base of the central axis, is a cup-shaped mass of com-
paratively firm tissue, in which the base of the stalk is fixed. It
connects with the lower portion of the inner peridium, and sends a thin
projection of tissue of less consistency upwards between the conical mem-
brane and the stalk. The base rests on the outer layer of the peridium.
The stalk itself is hollow at maturity, and is composed of air-containing

BA S IDIOM YCE TES

399*

tissue, with numerous compartments. To scatter the spores the stalk
elongates enormously, while it increases- in thickness at the same time ;
the peridium bursts at the apex, and the glebe is separated from the
inner peridial membrane and ele-
vated on the summit of the stalk.
When the spores are scattered,
the conical membrane (so-called
pileus] remains with the honey-
comb-like structure on its outer
surface attached to the apex of
the spongy stalk.

In Clathrus the development
of peridium and glebe agrees
with Phallus, but instead of a
stalk a net-like structure serves to
burst the peridium and elevate
the glebe.

Such forms as Mitremyces
(Nees ab Esenb.), Tulostoma
(Pers.), Polysaccum (DC.), and Sphaerobolus (Tode) exhibit other and
remarkable types of development. Though they do not properly fall
under any of the sections dealt with, they may be regarded as more
or less divergent from the Lycoperdaceae.

FIG. 331.— Aseroe ritbra Berk. Mature specimen.
The peridium is attached below ; the glebe is in
the middle of the radiating expansion (half natural
size). (From de Bary, after Berkeley.)

LITERATURE.

De Bary— Zur Kenntniss einiger Agaricinen (Bot. Zeit., 1859).

Bonorden— Beobacht. li. d. Bau d. Agaricinen (Bot. Zeit., 1858).

Bonorden— Mycologische Beobacht. (Phallus, Sphserobolus) (ibid., 1851).

Bonorden— Die Gattungen Lycoperdon u. Bovista, &c. (ibid., 1857).

Brefeld — Bot. Untersuch. ti. Schiinmelpilze, iii. (Leipzig, 1877).

Brefeld— For further development of Brefeld's views on the classification, &c., of

Basidiomycetes (with much research on the lower forms) see Unters. aus dem

Gesammtgebiete der Mykologie, Heft vii., 1888.
Corda— Icones Fungorum Prag (1837-1854).
Eidam— Die Keimung der Sporen u. d. Entstehung d. Fruchtkorper bei d. Nidu-

larieen (Cohn's Beitrage, ii.).
Fischer — Zur Entwick. d. Gasteromyceten (Sphetrobolus, Mitremyces) (Bot.

Zeit., 1884).

Hartig— Wichtige Krankh. d. Waldbaurne (Berlin, 1874).
Hartig— Die Zersetzungserscheinungen d. Holzes d. Nadelholzbaume u. d. Eiche

(Berlin, 1878).
Hesse— Mikroskop. Unterscheidungsmerkmale d. typischen Lycoperdaceengenera

(Pringsh., Jahrb. x.).
Hesse— Keimung d. Sporen von Cyathus striatus (ibid., x.).

400 ' FUNGI

Murray — On the outer peridium of Broomeia (Journ. Linn. Soc. Bot., xx., 1884).
Murray— On two new species of Lentinus, one of them growing on a large sclero-

tium (Trans. Linn. Soc., 1886).
Nees v. Esenbeck —Plant, mycetoid., £c., Evolutio (Nova Acta Acad. Leop.-

Carol., xvi.).

Pitra — Zur Kenntniss d. Sphserobolus stellatus (Bot. Zeit., 1870).
Rossmann— Beitr. zur Entwickl. d Phallus impudicus (Bot. Zeit., 1853).
Sachs— Morph. d. Crucibulum vulgare Tul. (Bot. Zeit., 1855, p. 833). (Omitted

from index to vol. of Bot. Zeit. )
Schlechtendal— Eine neue Phalloidee, nebst Bemerkungen ii. d. ganze Familie

(Linnsea, 1862).

Schlechtendal u. Miiller— Mitremyces Junghuhnii (Bot. Zeit., 1844).
Schmitz — Mycologische Beobachtungen, £c. (Linnsea, 1842).
Schmitz — Ueber Entw., Bau u. Wachstum von Thelephora sericea u. Iiirsuta (ibid.,

1843)-
Schroter— Ueber d. Entwickl. u. d. systematische Stellung von Tulostoma (Cohn's

Beitrage, ii.).

De Seynes — L'organisation des Champignons su,perieurs (Ann. Sc. Nat., ser. 5, i.).
De Seynes — Rech. sur 1. vegetaux inferieurs, i. Des Fistulines (Paris, 1874).
Sorokin — Developpement du Scleroderma verrucosum (Ann. Sc. Nat., ser. 6, iii. ).
Tulasne — Carpologia, i. (Paris, 1861).
Tulasne— Fungi Hypogoei (Paris, 1851).

Tulasne — Obs. sur Porganisalion des Tremellinees (Ann. Sc. Nat., ser. 3, xix.).
Tulasne— Nouvelles notes sur les fungi Tremellini et leurs allies (ibid., ser. 5, xv.).
Tulasne — De la fructification des Scleroderma comparee a celle des Lycoperdon et

des Bovista (ibid., ser. 2, xvii.).

Tulasne — Sur les genres Polysaccum et Geaster (ibid., ser. 2, xviii.).
Tulasne — Rech. sur 1'organ. d. Nidulariees (ibid., ser. 3, i.).

Tulasne— Description d'une espece nouvelle du genre Secotium (ibid., ser. 3, iv.).
Tulasne — See Explor. Sc, d'Algerie, p. 434 (Clathrus).
Van Tieghem - Sur le developpement du fruit, £c., des Basidiomycetes, £c. (Bull.

Soc. Bot. France, 1876). (See also Bot. Zeit., 1876.)
Vittadini — Monographia Lycoperdineorum (Mem. Acad. Torino, v., 1842).
Woronin — Exobasidium Vaccinii (Ber. d. Naturf. Gesellsch. Freiburg, 1867).

Of historical interest is —
Micheli -Nova Plant. Genera, 1729 (Phallus, Clathrus).

The student is also referred for both morphological and systematic treatises to the
numerous papers of Berkeley— to be found especially in the Ann. and Mag. of Nat.
Hist, and Hooker's Journal of Botany — and to his separate books ; for systematic
information particularly to the works of Fries, Persoon, Hoffmann (Icones Analytics
Fungorum, Giessen, 1861-65), Saccardo, Sylloge, vols. v. -vii. ; and for British forms
to Cooke's Handbook of British Fungi, 1871, and to Stevenson's Hymenomycetes
Britannici, 1886.

40i

SIXTH SUBDIVISION.
MYCETOZOA.

THE Mycetozoa are a group of organisms separated by a great gulf
from the Thallophytes, but presenting certain points of resemblance to
the Fungi which may here be indicated, while the amount of that resem-
blance and the degree of their divergence will be more fittingly esti-
mated at the end of this chapter. Their nutrition is saprophyti.c, and the
organs of reproduction are sufficiently like those of the Fungi to justify
the use of the terms sporange, spore, swarm-spore. The vegetative body,
on the other hand, differs in structure toto ccelo from any form of thallus.
It consists of a naked protoplasmic body, either a plasmode formed by
the coalescence of peculiar swarm-spores, or an aggregation of such
swarm-spores. The first case is characteristic of one class, the Myxo-
mycetes ; the second case of the other smaller class, the Acrasieae.

Class XXIII.— Myxomycetes.

The ripe spores of Myxomycetes are capable of germination at once,
and many of them retain this power for considerable periods, some for
as long as several years. Most germinate at the ordinary spring
or summer temperature, and in pure water, while others require a
nutrient solution. The germination of the spores of Cribrariese and
Tubulinse has not been observed, and the failure of the attempts to pro-
cure it may be owing either to the supply of unsuitable media or to a
necessity for a period of rest — more likely the former. In structure
the spores resemble those of fungi, as has been said. The wall
is either smooth or sculptured on the outer surface, and the protoplasm
contains one, sometimes two, nuclei. The act of germination consists of
the emission of a swarm-spore. The membrane opens and the proto-
plasm escapes with a creeping motion. This naked protoplasmic body
or swarm-spore then exhibits amoeboid movements, protruding and with-
drawing irregular processes, becoming more or less elongated, and

D D

402

MYCETOZOA

acquiring a cilium at the end of a finely pointed process. Its movements
are of two kinds : a hopping movement, during which it commonly

rotates round its longi-
3 2 t

tudinal
outline

axis, while the
undulates ; and

FIG. 332. — Chondrioderma difforme Rost. i, a ripe spore ;
2, the same germinating ; 3-5, swarm-spores ; 6, 7, the same
in amoeboid state ; 8, two in close contact ; 9, the same
coalesced ; 10, three in contact ; n, two after coalescence, the
third still free ; 12, young plasmode which has taken up

two spores into its substance (x 350). (From Sachs,
Cienkowski.)

after

a creeping movement,,
which takes place on a
firm substratum with the
cilium in advance. The
creeping is also some-
times accomplished by
the protrusion and re-
traction of pseudocodes.
The same swarm- spore
often moves both by
hopping and by creeping
alternately. After passing
through this stage, during
which swarm-spores mul-
tiply by simple division
into two (such division
taking place in some cases
even before leaving the
spore), the formation of
plasmodes begins. The
swarm-spores taking part
in this process are such
as have withdrawn their
cilia and exhibit creeping
amoeboid movements.
Several come into con-
tact and coalesce, thus
forming the beginning of
theplasmode. Others are
drawn towards it — how,
no one has ever found
out — and successively
coalesce with it, until a
. comparatively large plas-

t IG. 333. — Didymmm serpnla v r. A and B, plasmodes (natural x J . .

size). C, margin of a moving plasmode ( x about 200). (After mode IS formed With the
Reinke.)

appearance and move-
ments of a huge amoeboid swarm-spore without cilia. This plasmode-

MYXOMYCETES

403

nourishes itself and grows, acquiring, in the case of some Physareae, great
dimensions, and forming reticulated masses which may be measured by
inches. Fuligo varians (Somm.) (or as it is more commonly called ^Etha-
lium septicum (Fr.) or * flowers of tan,' from its appearing during summer
on tan) is such a body, but the plasmodes of other families of Myxo-
mycetes, as well as of some Physareae, generally remain very small in com-
parison with this. The appearance of the strands or branches of the plas-
mode (under the microscope) is that of a turbid granular mass bordered
by a clearer hyaloplasm. The surface of the plasmode of Physareae is in-
vested with a soft shiny envelope of a substance different from protoplasm.
The plasmodes of certain other forms are similarly invested with en-
velopes, as to the nature of which not much is known. The larger portion
of the granules contained in the plasmodes of Physareae are of calcium
carbonate ; granules contained in other
plasmodes require investigation. Nuclei
are abundantly present. Many foreign
bodies such as spores, diatoms, &c.,
are often found included in plasmodes.
Constant movement is maintained, and
the most characteristic is that of the pro-
trusion and retraction of pseudopodes.
Since protrusion is commonly more
active on one side than on the other, an
advancing movement of the whole is thus
brought about. Internal streamings, more
or less copious, answer to the amoeboid
movements. The external causes of move-
ments are : with reference to (i) illumina-
tion, they are negatively heliotropic ; (2)
water — they are positively hydrotropic,
i.e., when not about to form spores they
leave comparatively dry spots and move
towards moist places ; ($)food — they are
positively trophotropic, i.e., they move
towards nutrient substances (as might
be expected) ; (4) heat — within certain
limits they move towards the warmer side
of a surface unequally warmed. These
movements are without reference to the
direction in space in which they may

have to be made. It may be stated here that the process of nutrition
takes place only in the amoeboid states — the swarm-cell and plasmode.

FIG. 334. — Stemonitis fusca Roth,
sporange (natural size). B, capillitium
(x about 100). (After Reinke.)

404

MYCETOZOA

Resting states may occur at all motile stages of the life-history. Micro-
cysts are the resting states of swarm-spores. They round themselves off,
and are invested with a delicate membrane or only with a firm border.
Young plasmodes similarly form thicker-walled cysts, and mature plas-
modes form multicellular bodies— sderotes.

The spores of Myxomycetes are formed either endogenously within
sporanges, or on the free surface of sporophores (Ceratieae). Sporanges
are formed either by the whole plasmode becoming one, or the plasmode
divides into portions, each of which becomes a sporange. Such as are
situated on stalks begin as small swellings on a strand of the plasmode,
and by degrees acquire their mature form as the protoplasm ascends into

FIG. 335.— a, Ccratinm hydnoidcs Alb. and Sch. Piece of sporophore in act of forming.
b, Ceratiiim porioides Alb. and Sch. Piece of the margin of a sporophore ; spore-
formation beginning; two spores which subsequently become slightly ellipsoid on their
stalks, (a x about 68, b x 120.) (After Famintzin and Woronin.)

them. While this process of formation goes on the solid contents of the
plasmode are expelled. The interior of the mature sporange is either filled
with spores only, or more commonly there is also present a capillitium
consisting of numerous filaments traversing the cavity in all directions.
They probably serve as supports to the wall of the sporange in the first
instance, and may further be connected with its rupture and the dispersal
of the spores.

There are only two known species of Ceratium (Link), a genus
which forms free spores, i.e. not within a sporange. In this case the*
plasmode before spore-formation consists of a network of innumerable
branches from which cylindrical processes arise. The whole protoplasm

MYXOMYCETES 405

flows into these processes and finally breaks up into numerous polyhedral
portions. Each of these portions grows outward into the form of a ball
connected with the surface by a short narrow stalk. This sphere
acquires a wall, and the process of spore-formation is completed.

Class XXIV.— Acrasiese.

So far as is known the spores of Acrasieae germinate only in nutrient
solutions. The swarm-spores are never ciliated, and move only by
creeping in amoeboid fashion. Under unfavourable conditions they
encyst themselves, and form temporary resting states. They unite in
great numbers for the purpose of forming spores again, but the union
never amounts to coalescence into plasmodes. They are heaped together
as it were, and compose bodies of more or less definite form. In this
condition each swarm-spore becomes invested with a thin membrane,
though no common sporangial wall is formed. Guttulina(Cienk.) forms
simple spore-heaps, but in Dictyostelium (Bref.) and Acrasis (Van Tiegh.)
a stalk is formed by the swarm-spores in the centre of the mass becoming
transformed into series of cells with firm walls, and up it the rest of the
swarm-spores climb and form spores at the top.

DOUBTFUL MYCETOZOA.

De Bary repudiates the attempt made by Zopf to bring together
under this group an ill-assorted assemblage of lower organisms exhibit-
ing amoeboid movements. He considers such forms as Bursulla (Sorok.),
Protomyxa (Haeck.), Vampyrella (Cienk.), Nuclearia (Cienk.), Monas
amyli (Cienk.), Monadopsis (Klein), Pseudospora (Cienk.), Colpodella
(Cienk.), and Plasmodiophora (Woron.) to be doubtful Mycetozoa.
Plasmodiophora Brassicae (Woron.), which is parasitic on the roots
of Cruciferae, on which it produces large swellings, is common. The
ciliated swarm-spores penetrate into the parenchymatous tissue of such
roots. The cells affected swell to a great size, and large amceboids
appear in them, but it is not certain whether these are single swarm-
spores or small plasmodes formed by the coalescence of several. The
whole protoplasmic contents of a cell then break up into spores.

AFFINITIES.

De Bary, to whose remarkable investigations we owe the bulk of
our knowledge of the Mycetozoa, considers that the group differs

406 MYCETOZOA

distinctly from the Fungi (and still more from other plants) ' in all such
characteristics as do not belong to all organisms alike. . . . The differ-
ence would not be less decided, if the Mycetozoa were without their re-
markable amoeboid movements, for such movements are observed in
other vegetable cells which have not a firm membrane. The character-
istic mark of separation lies in the formation of plasmodes or aggrega-
tion of swarm-cells ' (* Comp. Morph.,' p. 443). He farther remarks that
the highest forms of the group give no evidence of close affinity with
yet higher organisms, and seeks for their relationship with Amoeba.
Guttulina, he points out, differs from such forms only by the aggregation
of its spores. Guttulina protea (Fay.) (Copromyxa protea, Zopf) even
forms solitary spores. This form then links the Amoebae with the more
highly differentiated Acrasieae, and these connect with the Myxomycetes.
Taking together this connection with the animal kingdom, and the want
of connection on the other hand with Fungi (to which they have a merely
superficial resemblance) or other plants, we are justified in placing them,
as de Bary does, 'outside the limits of the vegetable kingdom.'

LITERATURE OF MYCETOZOA.

Baianetzki— Influence de la lumiere sur les Plasmodia des Myxomycetes (Mem. Sc.

Nat. Cherbourg, xix., p. 321).
De Bary — Die Mycetozoen (Zeitsch. f. wissensch. Zoologie, Bd. x., 1859; and 2nd

edition, Leipzig, 1864).

Brefeld — Dictyostelium mucoroides (Abh. d. Senckenberg. Naturf. Gesellsch., vii.).
Brefeld — Untersuch. aus der Gesammtgebiete der Mykologie (Leipzig, 1884).
Cienkowski — Zur Entwickelungsgesch. d. Myxomyceten(Pringsh. Jahrb. wiss. Bot. , iii. ).
Cienkowski — Das Plasmodium (ibid. , iii. ).
Cienkowski — Ueber einige protoplasmatische Organismen (Guttulina). See Just's

Jahresber. for 1873, p. 61.

Cienkowski — Beitr. zur Kennt. der Monaden (Schultze's Arch. f. micros. Anat., i.).
Lister — Plasmode of Badhamia and Brefeldia (Ann. of Bot., ii., 1888, p. i).
Rostafinski— Versuch eines Systems der Mycetozoen (Dissertat. Strassburg, 1873).
Rostafmski — Slucowce (Mycetozoa) (Paris, 1875). A monograph admirably illustrated,

but written in Polish. The system in Cooke's Myxomycetes of Great Britain

(London, 1877) is adapted from Rostafinski's monograph.
Stahl — Zur Biologic der Myxomyceten (Bot. Zeit., 1884).

Strasburger — Wirkungd. Lichtesund d. Warmeauf Schwarmsporen (Jena, 1878, p. 69).
Strasburger — Zur Entwickgesch. d. Sporangien v. Trichia fallax (Bot. Zeit., 1884).
Van Tieghem— Sur quelques Myxomycetes a plasmode agrege (Bull. Soc. Bot. de

France, 1880, p. 317).
Zopf — Die Schleimpilze, in Schenk's Handbuch der Botanik, iii. (1887).

For further literature see De Bary's Comp. Morph., p. 453, and Rostafinski's
monograph.

407

SEVENTH SUBDIVISION.
PROTOPHYTA.

WHETHER the Protophyta should be reckoned as a distinct subdivision
from the Algae, or only as the lowest members of that great series, is a
question rather of convenience than of principle. In an ideal system of
classification founded exclusively on genetic affinities, those organisms
•would be regarded as 'protophytes' which were the earliest heralds of
the appearance of vegetable life on the surface of the globe. But, from
the structure and conditions of life of such organisms, it is impossible that
they can have been preserved to us in the fossil state, and it is only from
the comparative simplicity or complexity in the structure of an organism
that we can conjecture whether it is an archaic or a derivative form. And
here, as was remarked in the Introduction, we are extremely liable to be
misled if we neglect to take into account the phenomenon of the constant
appearance of degeneration or retrogression in the vegetable kingdom.
An organism may be simple in its structure either because it has never
risen, through countless ages, above the simplicity of its primeval ances-
tors, or because it has fallen back from a more complicated condition.
The object of the scientific systematist should be to separate, so far as
possible, between these two sets of organisms, to include the former
among his lowest class of protophytes, and to relegate the latter in each
case to the class from which they have degenerated. But this task is
attended with great difficulties, and is often well-nigh impossible. An
organism may display degeneration of one set of organs, while another
set manifest no such degeneration and have even continued to develop.
We may take it indeed as a general law that wherever you have either
the vegetative or the reproductive organs strongly developed, while the
other set are very feeble or altogether wanting, you have prima fade
evidence of retrogression. But, on the other hand, degeneration may
take effect in all the organs of a plant, leading to retrogression in all lines
towards, it may be, the archaic form. As knowledge advances, the constant
tendency will be to transfer to this class of retrogressive members of
higher families forms previously regarded as protophytal.

4o8 PRO TOPH VTA

While the Schizophyceas or chlorophyllous Protophyta approach very
closely to the lowest forms of Algae, the Schizomycetes or non-chloro-
phyllous Protophyta exhibit greater affinities, as de Bary has shown, with
the chlorophyllous forms than with any family of Fungi, Grouping,,
therefore, all these lowest forms of vegetable life, whether containing
chlorophyll or not, into a single subdivision of Cryptogams, it will be
most convenient to discuss them under two heads, as distinct and to a
certain extent parallel series.

GROUP I.— SCHIZOPHYCEyE.

An attempt is here made to bring together those chlorophyllous;
forms which, in the present state of our knowledge, we must regard as-
primordial ; while others, almost equally simple in structure, have been
referred to the classes of which they appear to be retrogressive members.
The group now under consideration comprises the greater number of the
forms of vegetable life which are unicellular, which display no true pro-
cess of sexual reproduction, and which contain chlorophyll.

Limited in this sense, the Schizophyceae may be divided into three
well-marked classes, the Protococcoide^ the Diatomacecz, and the Cyano-
phycece. In the Cyanophyceae are included those forms in which the
pure green colour of the chlorophyll is masked by a blue-green pigment
dissolved in the cell-sap, an arrangement not found except in plants of
the very simplest structure. The position of the Diatoms has been a
subject of much controversy among systematists. They display in
some respects a similarity to the Desmids ; but, for reasons given below,
we are disposed to consider this resemblance as apparent rather than
real, and to regard the Diatomaceae, not as a family derived from the
Desmidiaceae by retrogression, but as a primordial type of great simplicity
of structure. In the Protococcoideae are included those forms in which
the pure-green of the chlorophyll is not concealed by the blue-green
colouring matter of the Cyanophyceae, nor by the brown colouring
matter of the Diatoms. It is unquestionably from them that all the
higher forms of vegetable life have been derived, and the boundary line
between the Protococcoideae and the lower forms of Algae is one that
cannot be accurately laid down.

LITERATURE.

The literature of the Schizophycese is included under that of Algae, or in the
works specially named when treating of the separate classes and orders.

PROTOCOCCOIDE/E 409

Class XXV.— Protococcoideae.

In this class, the Chlorophyllophyceae of some writers, are included
those simplest forms of vegetable life in which the endochrome consists
of pure chlorophyll of its natural green colour, sometimes replaced,
to a larger or smaller extent, by a red pigment, but the cell-sap never
pervaded, as in the Cyanophycese, by a soluble blue colouring-matter.
The individuals are of microscopic size, and may be either motile or
resting, and very commonly the same species occurs in both conditions.
The motile or protococcus form is, in the lower members, strictly unicel-
lular, consisting of chlorophyllous protoplasm either naked or invested
with a very delicate coat of cellulose or of a carbohydrate nearly allied
to cellulose, usually developing but little or no mucilage, and moving
freely through the water by means of a pulsating vacuole and two vibra-
tile cilia. In the resting condition the individuals are invested by a
much thicker cell-wall, and have a tendency to congregate or coalesce
i n to palmelloid families, and to enclose themselves in a common gela-
tinous envelope. In this state they multiply rapidly by repeated bipar-
tition. The palmelloid form may be derived directly from the proto-
coccoid, the protococcus-cells coming to rest, losing their cilia, and
investing themselves with a thicker cell-wall of cellulose ; or, in the
higher members, the individual consists of a number of gonids, chloro-
phyllous masses of protoplasm, enclosed in a common watery hyaline
envelope of mucilage, and propagation takes place by the escape of
these gonids from the envelope in the form of naked biciliated zoospores
or swarm-spores, closely resembling protococcus-cells, which, after going
through a motile period, come to rest, lose their cilia, invest themselves
with a coat of cellulose, and multiply by repeated bipartition in the
palmelloid form. In some cases these swarrn-spores are of two kinds, the
smaller ones being conjugating zoogametes. In no case is the individual
filiform and divided by transverse septa, as in the higher families of
the Cyanophyceae.

It cannot be too strongly insisted on that this class is a purely pro-
visional one. Many of the forms at present included in it are, in all
probability, nothing but stages in the development of algae of consider-
ably greater complexity of structure belonging to widely separated
families. The external resemblance between the Protococcaceae and the
Chroococcaceae, and 'the parallel series of forms in these two families,
does not probably represent any genetic affinity. There is, on the other
hand, an undoubted alliance with the Pandorineae, through Chlamy-
dococcus and Chlamydomonas, as well as with the Hydrodictyese and

4io PROTOPHYTA

Siphoneae through intermediate forms. The Protococcaceae converge
also on the boundary line between the vegetable and animal kingdoms ;
and, since it has been demonstrated that the power of forming chloro-
phyll and starch is not of itself sufficient to determine an organism to
belong to the vegetable kingdom, it is impossible to draw a hard and
fast line between the Protococcaceae and the Flagellate Infusoria, with
which they are connected by such forms as Euglena and the Peridinieae.
The Protococcoideae are divided into two orders, the boundaries of
which are very ill-defined : the Eremobice and the Protococcacece.

LITERATURE.

Ehrenberg — Die Infusionsthierchen, 1838.

Nageli — Neuern Algensysteme, 1847, pp. 123-132; and Gattungen einzelliger Algen,

1849.
Braun — Verjiingung in der Natur, 1851 (Ray Soc. Bot. and Phys. Memoirs, 1853) ;

and Algarum unicellularum genera, 1855.

(Also the Memoirs referred to under the separate genera, and the literature ot
Algre generally.)

ORDER i. — EREMOBL*: (including SCIADIACE^:).

In this ill-defined family, known by some writers as Characiaceae,
the limits of which are very difficult to assign, are included a number of
genera distinguished from the Protococcaceae by their greater complexity
of structure. They are mostly fresh-water, but comprise also a few
marine organisms, free-swimming or attached to algae. In the larger
number of genera each individual consists of a number of green proto-
plasmic bodies, pseudocysts or gonids — that is, masses of chlorophyllous
protoplasm of defined outline but not clothed with a definite cell-wall of
cellulose — sometimes of considerable size, enclosed in a common trans-
parent hyaline envelope, which may be simple or may branch in an
arborescent manner. In some genera the hyaline envelope is wanting.
Multiplication takes place by simple division, or by the transformation of
the gonids into zoospores, which sometimes display a differentiation into
larger megazoospores and small er microzoospores or zoogametes. Although
conjugation of these gametes has hitherto been observed only in a few
cases, this appears to be the earliest indication among chlorophyllous
organisms of a differentiation of sexual elements ; and the Eremobiae
clearly approach those algae which multiply by conjugation through
Botrydium, or through such forms as Endosphaera, Chlorochytrium, and
Phyllobium, or again through Hydrodictyon. Lagerheim (Ber. Deutsch.
Bot. Ges., 1884, p. 302) asserts the presence of chromatophores in
Glaucocystis (Itz.).

PRO TOCOCCOIDE&

411

In the following paragraphs only the more remarkable or better
Tmown genera are described.

In Sdffdium A. Br., made by some writers the type of a distinct
family SCIADIACE^E, the peculiar mode of germination of the zoospores
gives rise to a remarkably complicated structure. Each individual consists
at first of a single elongated cylindrical cell. The green protoplasmic
contents of this cell break up ultimately into a number of biciliated
zoospores, which are set free by the upper portion of the cell -wall be-
coming detached in the form of a cap.
The zoospores do not, however, escape,
but germinate while still attached to
the mother-cell, giving rise to a cluster
of smaller cylindrical cells springing
from the apex of the mother-cell. This
may go on until the colony consists of
as many as four generations, giving
the appearance of a minute branching
shrub. The zoospores of each genera-
tion are smaller than those of the pre-
ceding one, and it is probable that
those of the last generation, which escape
altogether from the parent-cell, are
conjugating zoogametes. It is pos-
sible that a form allied to Sciadium may have been the starting-point of
the Siphonocladaceae, with which family it shows a certain affinity, as, for
example, with Valonia.

Chlorothecium Bzi. (Malpighia, 1888, p. 250) occurs in the form of
palmeiloid colonies with a thick and firm cell-wall on aquatic plants.
From the cells of these colonies are developed zoosporanges, or rather
gametange:, without any alteration of their primitive form ; from each
gametange there escape from two to four swarm- spores, or occasionally
only one, each provided with a single cilium and a conspicuous red
pigment-spot. These swarm-spores are zoogametes, conjugating by
gradual fusion. After hibernating the contents of the zygosperm break
up into two masses, each of which escapes as a non-sexual zoospore, so
that the zygosperm is itself a zoos'porange. From these zoospores are
again formed the palmeiloid colonies, in which form Chlorothecium
may multiply itself non-sexually without producing zoogametes.

The position of Halosphara (Schmitz, Mittheil. Zool. Stat. Neapel,
1878, p. 61) is very doubtful. Each individual is a minute green globe,
just visible to the naked eye,, as much as 0-5 mm. in diameter, floating
on the surface of the sea, and bearing an external resemblance to Volvox.

FIG. 336. — Sciadium arbuscnla A. Br.
(magnified).

412

PROTOPHYTA

Each cell contains a nucleus and a vacuole ; the green protoplasmic
contents break up ultimately into zoospores of a very peculiar form,
conical, with two cilia attached to the nearly flat base, recalling those of
^^^.-^ Hydrurus (p. 256).

In Dictyosphcerium Nag.,.
which ought possibly to be
placed under the Ccenobieae, the
free-swimming colony is com-
posed of globular or kidney-
shaped green gonids connected
together by delicate threads of
mucilage. New colonies are
formed by repeated biparti-

B ^^^^^^^^ A N tion of the gonids, which fre-

FIG. w.~-Hapiosph*ra -viridis Schm. Globe ( x 80), quently exist for a time without

any enclosing cell-wall. Mis-

chococcus Nag. consists of minute globular gonids connected together
in an arborescent manner and enclosed in a hyaline envelope, the whole
colony attached to fresh-water algae. Borzi (Malpighia, 1888, p. 133)
describes also a palmelloid form of Mischococcus, the cells of which
give birth to megazoospores with only a single cilium. The dendroidal
form may spring either from these zoospores or directly from the
palmella- cells ; its cells also produce uniciliated swarm-spores, similar to
the zoospores but smaller. They are apparently zoogametes conjuga-

FIG. 338. — Dictyosphczrium rcniforme
Buln. (x 400). (After Cooke.)

FIG. 339. — Mischococcus confenncola Nag.
(X4oo). (After Cooke.)

ting to produce a biciliated zoosperm. Botrydina Breb., found on
moist ground, trunks of trees, &c., is composed of a number of minute
gonids enclosed in a pear-shaped or globular hyaline envelope, as much
as o-i mm. in diameter, and resembling Aphanocapsa among the
Chroococcaceae. It may possibly be allied to Botrydium.

Chararium A. Br. is a minute green organism attached by a gela-
tinous stalk to algae or other fresh-water plants, often in groups. It is

PROTOCOCCOIDEsE

ovate or pear-shaped, 0*02-0 025 mm. in diameter in the larger species,
often apiculate or spinous at the apex. The cell-contents divide, by
successive bipartitions, into zoospores, which commence swarming while
still within the mother-cell, indicating an approach
to Hydrodictyon. They escape through a lateral or
terminal fissure. Nearly allied to Characium are
Hydrocytium A. Br., also met with in fresh water,
and Hydrianum Rabh., found in similar localities.
In the last genus the zoospores also escape at the
apex. In Apiocystis Nag. a large number of gonids
are sparsely scattered through a stalked pear-shaped
gelatinous envelope attached to fresh- water algae.
They occur chiefly in the periphery, and are ulti-
mately converted into zoospores.

Codiolum A. Br. is a club-shaped marine organism, about 0*04 mm.
in diameter, and four to six times the length, attached to rocks or sea-
weeds. It is propagated by zoospores, or, according to some observers,
also by resting hypnospores. Hauckia Bzi. (Nuov. Giorn. Bot. Ital.,

FIG. 340. —Characium
ornithocephaluin A.
Br. (x 600). (After
A. Braun.)

FIG. 341. — Apiocystis Brauniana Nag.
( x 100). (From nature.)

FIG. 342. — Codiolum gregarium A. Br. (magnified).
(After Hauck.)

1880, p. 290) grows on rocks exposed to the sea. The gonids are placed
in pairs on a long hyaline stalk ; it produces zoospores of two different
sizes, but no process of conjugation has at present been observed.

PROTOPHYTA

(Trans. Irish Acad., 1881, p. 27) is also a marine genus,.
allied to Characium and Hydrocytium ; but the zoospores escape
through a terminal instead of a lateral fissure.

Of free-swimming forms occurring in fresh water, Nephrocythnn
Nag. consists of kidney-shaped gonids enclosed
in a hyaline envelope. Although the production of
zoospores has not been detected in this genus, its
position is probably here, though its true place
may possibly be among the Sorastreae. Dangeard
(Bull. Soc. Linn. Normandie, i., 1888, p. 196) has
observed a mode of propagation by the formation
of daughter-colonies within the membrane of the
parent-colony. In Ophiocytium Nag., the origi-
na^y cylindrical individual becomes curved in .a
serpentine manner, and produced at one extremity
into a hyaline spine. The zoospores escape by the detachment of the
cap-like apex of the hyaline envelope.

In Hormospora Breb. the free-swimming individual or colony con-
sists of a very elongated straight or bent cylinder, sometimes branching,
the gonids arranged in a single or double row within a dense hyaline
envelope. No formation of zoospores has been observed. Cylindro-
capsa (Reinsch) (see p. 227) is placed here by some authorities.

FIG. w.-Ncphrocytium
(Affer cSke") ( x 30o)'

FIG. 344-— Hormospora mntabilis Bn;b. ( x 200). (From nature.)

Although in the majority of the genera named above only one kind
of swarm-spore has hitherto been observed, it is highly probable that
some or all of them produce both megazoospores and zoogametes with
a sexual function.

LITERATURE.

Fresenius— Abhandl. Senckenberg. Naturf. Gesell., iii., 1856-8, p. 237.

Archer — Microscop. Journ., 1866.

Zukal — Oesterr. Bot. Zeitschr., 1880, p. u. *

Holmes — Journ. Linn. Soc., xviii., 1881, p. 132.

Borzl — Nuov. Giorn. Bot. Ital., 1882, p. 272 ; and Studi Algologici, 1883.

Lagerheim— Bot. Centralbl., xii., 1882, p. 33 ; and. Oefv. Vetensk. Akad. Forhandl.,

Stockholm, 1885, p. 21.

Klebs— Unters. Bot. Inst. Tubingen, i., 1883, p. 233.
Bennett— Journ. Micr. Soc., 1887, p. 9; and 1888, p. 2.

PRO TOCOCCOIDE.E 4 1 5

ORDER 2.— PROTOCOCCACE.E (including PALMELLACE^E).

In this family are included a number of organisms of very simple
structure, many of which occur both in the free-swimming (protococcus}
and in the resting (palmella] condition. In the former state they bear
a very close resemblance to the zoospores of the higher algae. Other
forms are known in one condition only, in which they have a free-
swimming motion without the aid of cilia.

Protococcus Ag. is one of the commonest objects in fresh water,
especially stagnant rain-water, forming masses of a bright green colour,
either floating free or attached to a submerged or floating object, but
destitute in this state of any spontaneous power of motion. In this
palmella-condition each individual consists of a nearly spherical cell,
varying between forty and fifty microns (= '04-'o5 mm.) in diameter,
which multiplies rapidly by repeated bipartition of its contents. The
bright green endochrome has usually
intermixed with it a larger or smaller
quantity of a red pigment, the propor-
tion varying according to the conditions
of life, &c. The change to the active
condition takes place in the following
way. The protoplasm withdraws itself
from the cell- wall, and escapes in the

FIG. \4$.—Protocecciu pluvialis Ktz.

form Of an OVOld maSS provided With A, motile condition; B, palmella condi-

, j , , ., ., .,. tion(x25o). (After Cohn.)

two very long and slender vibratile cilia

and a pulsating vacuole, by the agency of which it is driven rapidly through
the water. The pulsation of this vacuole has been explained by the
alternate absorption from the water, through the agency of the chloro-
phyll, of carbon dioxide, and the expulsion of free oxygen resulting from
the process of assimilation. In some cases the contents of the mother-
cell do not escape as a single zoospore, but break up before escaping
into eight or more smaller zoospores. The motile protococcus may
be either entirely without cell-wall of cellulose, or may have a very
delicate one, through orifices in which the protoplasmic cilia pro-
trude. Some observers state that there are two kinds of zoospore in
Protococcus — microzoospores and megazoospores, and that conjuga-
tion takes place between the latter ; but this last statement at all
events requires confirmation. After swimming about rapidly for a
time in all directions with an apparently spontaneous movement, the
motile protococcus comes to rest, loses its cilia, becomes encysted, or in-
vested with a thick cell-wall of cellulose, and again enters the palmella-

4i 6 PROTOPHYTA

condition in the form of resting-spores, which may become dried up and
retain their vitality for years as a dry powder, resuming their activity when
again placed in water. McNab (Ann. & Mag. Nat. Hist, 1883, p. 124)
has, by the use of osmic acid and carmine, detected a nucleus in the
free ciliated state of Protococcus, and also in individuals in which cell-
division is going on.

When in an active condition in sunlight, Protococcus gives off into
the surrounding water large quantities of oxygen, the result of the activity
of its chlorophyll, thus contributing to render it habitable for animal
life. The amount of the red pigment varies greatly. It is often con-
fined to a small spot near to the point of attachment of the cilia, the
* pigment-spot,' bearing a close resemblance to the ' eye-spot ' of the
Flagellate Infusoria. If present in larger quantities, so as to give a red
tint to the entire organism, this is known as Hasmatococcus (Ag.). In
the palmella-condition this form frequently presents the structure and
appearance of a blood-red incrustation on rocks and stones, when it has
been described as Palmella cruenta (Ag.) and Porphyridium cruentum
(Nag.). Very closely allied are the Palmella prodigiosa (Mont.) (Monas
prodigiosa, Ehrb.), which forms blood-red spots on bread, potatoes, &c.,
and the Palmella nivalis (Hook.) (Protococcus nivalis, Ag., Chlamydo-
coccus nivalis, A. Br.), which, under the name of ' red snow,' frequently
covers large tracts of snow in arctic and alpine regions in a very short time.
Phipson (Compt. Rend., Ixxxix., 1879, pp, 316, 1078) has examined
the red colouring-matter of Palmella cruenta, and finds it to consist of
minute globules about four microns (-004 mm.) in diameter, closely
resembling those of the hsemaglobin of blood, but somewhat smaller.
He proposes for the pigment the name palmellin. It is soluble in
water, but insoluble in alcohol, ether, and carbon bisulphide. Like
haemaglobin it contains traces of iron. Other lowly-organised snow and
ice plants besides Palmella nivalis are brightly coloured, and appear to
perform an important function in melting the snow by their strong
absorption of the rays of heat. In addition to palmellin, Palmella
contains also xanthophyll, and a small quantity of another substance of
the nature of camphor and possessing a marshy odour, which Phipson
calls characin^ and which is present in other terrestrial and fresh-water
algae, and especially in Chara. In the haematococcus-condition it is
sometimes impossible to detect directly the presence of chlorophyll ; but
experiments by Engelmann (Rev. Internat. Sci. Biol., 1882, p. 468, and
Bot. Zeit., 1882, p. 663) seem to show that there is always a certain
amount of chlorophyll present, though it is possible that the power
which Haematococcus undoubtedly has of decomposing carbon dioxide
may be due to the presence of other substances allied to chlorophyll,
but differing from it in colour.

PRO TOCOCCOIDE&

417

It is impossible to distinguish between the genera Protococcus (Ag.),
Pleurococcus (Meneg.), and Palmella (Lyngb.) ; but it is doubtful
whether Chlamydococcus (A. Br.) and Chlamydomonas (Ehrb.), which
undergo much more complicated changes of form, and in some condi-
tions very closely resemble Protococcus, have been rightly identified with
it (see p. 299). Haematococcus Butschlii (Blockmann, Ber. Heidelberg
Naturh. Ver., 1886) probably belongs to Chlamydomonas. Schnetzler

FIG, 346. — Glochiococcns anglicus Benn.
( x 200). (From nature.)

FIG. 347.— Chlorococcum gigas Griin. (x 300).
(After Cooke.)

(Bull. Soc. Vaud. Sc. Nat, 1882, p. 115) regards Palmella uvaeformis
(Ktz.) as a stage in the development of a Stigeoclonium ; while Ander-
sson identifies it with Draparnaldia.

Glochiococcus (Lagerh.) (Acanthococcus, Reinsch, Ber. Deutsch. Bot.
Ges., 1886, p. 237) differs from Palmella in the cell- wall, which is thick
and lamellated, being in most of the species furnished with warts,
spines, or other prominences. The cells, which closely resemble the
zygosperms of desmids, divide into eight or sixteen daughter-cells, which
remain but a short time in connection, being set free by the deliques-
cence of the outer membrane.

Chlorococcum (Fr.) is analogous to Chroococcus among the Chroo-
coccacese. Several species are common in pools or on moist walls or
rocks. In C. gigas (Griin.) the cells are as much as
o'0 1-0-015 mm. in diameter, and either a single cell
or a colony of cells is enclosed in a very thick lamel-
lated hyaline envelope. In Glaocystis (Nag.), corre-
sponding to Gloeocapsa among the Cyanophyceae,
the cells are associated in families of two, four, or
eight, each family being enclosed in a lamellated gela-
tinous envelope, in addition to the similar envelope which encloses each
cell. In Schizochlamys (A. Br.) the cells escape from the surrounding
envelope by the latter splitting into two or four equal parts. Eremosphcera
(de By.) is a beautiful bright green globe, 0-1-0-15 mm- m diameter,
floating free in bog-pools, and enclosed in a thin hyaline envelope.

E E

FIG. 348. — Schizochlamys
gelatinosa A. Br. (x
600).

4J8 PROTOPHYTA

Botryococcus Ktz. consists of mulberry-like masses of thick-walled
cells united together into colonies, with no investing membrane, or only
a very slight one ; it is found in bog-pools, and is endowed with a

rotating as well as a free-swimming
motion. It has possibly a genetic
affinity with the Coenobieae.

In Urococcus Hass. the endo-
chrome is bright red, and the cell-
walls throw off successive layers of
FIG. w.-Botryo- ^^^^ mucilage, which form together a

' FIG. 350. -Urococcus cylindrical or fusiform stalk, cora-

POSed> in SOme Species, of a large

number of distinct annular segments.
Tetraspora Lk. is composed of cells associated together in large
numbers in a single layer imbedded in a copious gelatinous envelope.
It has no spontaneous motion, and is possibly allied to Merismopedia,
and also appears to have affinities with the Ulvaceae. Gay (Bull. Soc. Bot.
France, 1886, Sess. Extraord., p. 41) records in T. gelatinosa (Desv.) the
formation of biciliated zoospores, one being produced from the contents
of each cell, and afterwards becoming encysted into a resting-spore.
In Palmodictyon Ktz. the gelatinous envelope is filiform and branched,
and cell-division takes place chiefly in two directions only.

The position of the following genera is very uncertain. Very
little is known of their mode of reproduction, and they lack the
copious gelatinous envelope which is characteristic of the family gene-
rally. They are mostly but feebly endowed with spontaneous move-
ments, and may probably be a resting
condition of algae or protophytes classed
under entirely different groups.

Raphidium Ktz. includes several
species very common in fresh water,
and consisting of very narrow fusiform
acuminate cells, usually curved, solitary
FIG. 352.— Scene- or joined together in bundles, the cells

desmus obtusus , - . , , • j i_ i •

Mey. (x 4oo). being in the latter case united by their
(From nature') middle, Cell-division takes place in one

Ktz. (x 800). j- • i «

(From nature.) direction Only.

Under the class Palmellaceae are

usually placed also the genera Scenedesmus Mey. and Polyedriuin
Nag., but their rank as independent organisms is exceedingly doubtful.
Their probable position has already been discussed under the heads of
the Sorastreae and the Pediastreae respectively (see pp. 303 and 299).

PRO TOCOCCOWEsE 4 1 9

Reinsch unites Polyedrium with three other genera to make up a sepa-
rate family, POLYEDRIACE^E, belonging to Palmellaceae.

Richter connects Glceocystis with the Chroococcaceae, and hence
genetically with higher forms of algae. Cienkowski regards Pleuro-
coccus, Glceocystis, and probably other genera of Protococcaceae, as
resting conditions of Chlamydomonas, or of similar organisms classed
among the Ccenobieae which multiply by conjugation. Under suitable
conditions he states that they can all be made to produce biciliated
zoospores with two contracting vacuoles and a nucleus. The part taken
by some Protococcaceae in the development of lichens has already been
discussed on p. 318.

LITERATURE.

Cohn — (Protococcus) Nov. Act. Akad. Cses. Leop.-Carol., xxii., 1850, p. 605 (see

Ray Soc., Bot. and Phys. Mem., 1853, p. 515).
Cienkowski — Bot. Zeit., 1865, p. 21.

Rostafinski — (Hsematococcus) Mem. Soc. Sc. Nat. Cherbourg, 1875, P- J42-
Lagerheim — Oefv. Svensk. Vetensk. Akad. Forh., Stockholm, 1882, p. 47 ; and

1883, p. 37 (Bot. Centralbl., xii., 1882, p. 33).

Richter— Hedwigia, 1880, pp. 154, 169, 191 ; 1884, p. 65 ; and 1886, p. 249.
Dangeard — (Chlamydococcus) Ann. Sc. Nat., vii., 1888, p. 105.
Reinsch —(Polyedrium) Notarisia, 1888, p. 493.

Class XXVI.— Diatomaceae.

The family of Diatoms — called by the older writers Bacillariacese —
includes a very large number of genera and species, all microscopic,
some of them extremely abundant in running, stagnant (but not putrid),
and salt water. The individuals are strictly unicellular, and are either
free-swimming and isolated, or attached to one another in a linear series
or in zigzag chains, adhering to one another by means of small annular
cushions, or fixed to some solid object by a simple or compound
gelatinous stalk. They are, with very few exceptions, characterised
by the presence in the cell-wall of a deposit of silica, by which it becomes
converted into a hard but thin and perfectly transparent shell ; and this
is always invested in a thin gelatinous envelope. Some species are
closely adherent to submerged plants by the whole of one side ; in
other cases whole colonies are enclosed in a common gelatinous en-
velope, which assumes the form of a simple or compound tube, flattened
plate, or globular mass. This is especially the case with the marine
species.

Each individual or frustule consists of two more or less symmetrical

EE 2

420

PROTOPHYTA

halves known as valves ; the silicified cell- wall of the older of these
halves is slightly the larger of the two, fitting on to the younger one
like the lid of a cardboard box. The cell-wall is composed of an
organic matrix closely allied in composition to cellulose, impregnated
with silica or a compound of silica ; either of these two ingredients can

be removed and the other left behind,
the former by calcination, the latter
by the action of hydrofluoric acid. In
those species which are fixed by a
gelatinous stalk, this stalk is also com-
posed of a substance allied to cellu-
lose. The overlapping edge of one of
the two valves over the other is called
the girdle or hoop ; this girdle may be
simple, or there may be several. In
many species — and probably in all,
if examined with a sufficiently high
power — each valve is marked with a
number of rows of very fine perfora-
tions, which, except under the very
highest microscopic powers, appear
as if confluent into striae or furrows.
There may be two or three sets of
these apparent striae, but they do not,
as a rule, reach to the centre of the
valve. So constant is the arrange-
ment and the fineness of these stria-
tions in some of the more abundant
species, that they furnish an admirable
test for the definition and angular
aperture of microscopic lenses. Some
species of Navicula (Bory) and Pleu-
rosigma (Sm.) are especially used for
this purpose. Some marine genera
in particular (Triceratium, Ehrb.,
Coscinodiscus, Ehrb., &c.) are cha-
racterised by the beautiful honeycomb-like areolation of the cell-wall,
due to the presence in it of actual chambers, which may or may not be
covered by a thin membrane. The membrane at the bottom of these
chambers is also most minutely perforated, constituting what is known
as the secondary markings. In describing diatoms, the aspect in which
the girdle is turned towards the observer is spoken of as fae front, girdle,

h

FIG. 353. — Pinnularia viridis Sm.
valve-view ; B, girdle-view (diagrammatic).
r, furrows ; m, raphe ; g, central node ;
A-, terminal nodules ; v*, outer and older
valve ; z, inner valve ; «, secondary lines
( x 800). (After Pfitzer.)

DIATOMACE^

421

FIG. 354 A.— Anom&neis spherophora. a, c, girdle-
view ; b, valve- view. The endochrome- plates are
shaded ( x 900). (After Pfitzer.)

tir zonal view ; the aspect in which the surface of the valve is turned to-
wards the observer is the side or valve view. In many diatoms the
central space on the valve view
not occupied by transverse
striae shows at its middle and
at each end a strongly refractive
thickening known as a node or
nodule ; and these nodules are
connected with one another by
a longitudinal line or rib — the
raphe or suture. The primary
classification of the genera of di-
atoms usually adopted depends
on the presence or absence of
this raphe.

Each diatom-cell contains a
nucleus and a nucleole. The
chlorophyll occurs in the form
of plates or bands arranged
with more or less symmetry, and there are usually also drops of oil,
especially when conjugation is about to take place. A very few di-
atoms are green ; but in the great majority of cases the colour of the
chlorophyll is obscured by a
characteristic brown pigment
known as diatomtn, readily
soluble in alcohol, forming a
brownish-yellow solution which
is only slightly or not at all
fluorescent. With concentrated
sulphuric acid it assumes a
beautiful blue-green colour.
Petit (Brebissonia, 1879-80,
p. 81) has very carefully in-
vestigated the chemical and
physical properties of the
colouring matter of diatoms.

.. ,. . FIG. 354 B. — Gompkonema constrictum Ehrb. s,

He regards diatOmm aS a valves, side view, showing nucleus ; g,, glt, girdle-

views ; q, transverse section through middle of cell,

f 3'

showing silicified cell-wall, one half overlapping the
other ; k, nucleus ; />, dense protoplasm ; <f ., g,,,
girdle surfaces (magnified). (After Pfitzer.)

compound of chlorophyll -and
phycoxanthin, and as- having
a great analogy with the chlo-
rophyll of the higher plants, the two spectra being very similar.

Many of the solitary species of diatom, such as those belonging to

422

PROTOPHYTA

the genus Navicula, possess, the power of propelling themselves through
the water with considerable rapidity backwards and forwards in the
direction of their longer axis, often with a jerking motion, or of creeping
along the bottom on some submerged substance. The cause of this
motion is a subject on which a large amount of attention has been be-
stowed. Nageli attributed it to osmotic currents passing through the
cell-wall. Ehrenberg believed that he had actually seen, in some cases,
the extrusion through the raphe of vibratile cilia, in other cases of a

' foot ' or pseudopode ; but
his observations have not
been confirmed by others.
The explanation of the mo-
tion now generally accepted
is that of Schultze— that it
is due to the contractility
of the protoplasm which is
exuded outside the cell-wall.
Mereschkowsky (Bot. Zeit.,
1880, p. 529) states the
arguments in support of the
various views with regard
to the causes of the mo-
tion, and sums up in favour
of the theory that it is the
result of osmotic currents
within the siliceous cell-wall.
Hallier, again (Unters. iiber
Diatomeen, 1880), considers
it due to a contractile layer
of protoplasm, and asserts
that at an early stage di-
atoms have no true cell-
wall of cellulose. Onderdonk
(Microscope, 1885, p. 205) also attributes it to ' external cyclosis.'

Diatoms have three modes of multiplication : — by simple division,
by auxospores, and by a kind of conjugation which is regarded by some
as sexual ; but the three modes pass gradually one into another. Simple
division always commences with the bipartition of the nucleus. When
it is about to commence the two valves separate from one another, the
contents divide into two daughter-cells, and new siliceous valves are
formed inside the old ones, and therefore necessarily smaller than they.
The valves of the new individual are formed necessarily one after the
other, the one formed later being smaller. The individuals produced in

FIG. 355.— Stages in the formation of the auxospore of
Frnstnlia saxonica Ag. s, valves ; ///, gelatinous en-
velope ; c, endochrome-plates ; a, auxospore (x 1,200).
(After Pfitzer.)

DIATOMACE& 423

this way constantly diminish in size, until the original size is restored by
the formation of an auxospore, resulting from the concents leaving the
siliceous valves, which fall away from one another, and increasing in
size, either by simple growth or by the coalescence of two auxospores
produced in the same mother-cell. In other cases two distinct auxo-
spores appear to be produced from the contents of a single mother-cell.
The auxospore finally becomes invested in a new siliceous cell-wall. In
those cases in which the process has been most carefully followed out,
the auxospore does not appear to owe its origin to any process of true
sexual union.

In some genera what is regarded by some as a true process of con-
jugation has been observed, a zygosperm being produced as the result of
the coalescence of the protoplasmic contents of two different individuals.
The conjugating diatoms are here placed
side by side enclosed in a common gela-
tinous sheath ; the contents of each escape
by the falling apart of the two valves, and
unite into a single zygosperm. In other
cases two zygosperms result from the con-
jugation of a pair of cells. The protoplasm
of each cell, as it escapes from its siliceous
wall, puts out two protuberances ; these
meet in pairs, and the whole contents of
the pair of mother-cells finally pass into
the two zygosperms, which complete their FlG- -,

J ,A turn khrb. attached by gelatinous

development in precisely the same way as stalks to a fresh-water aiga

i -i-» /v-i /T (greatly magnified).

the auxospores. Buffham states (Journ.

Quek. Micr. Club, 1885, p. 131) that in the conjugation of Rhabdomena
(Ktz.) the 'male' frustule is always smaller than the 'female' frustule,
and that the union is effected by the 'male' frustules attaching them-
selves in numbers to any part of the girdle of the 'female' frustule.
De Bary and Pfitzer do not regard the fusion of the cell-contents
of diatoms as in any sense a true process of sexual conjugation. De
Bary (Bot. Zeit., 1858, Supplement, p. 61) thus summarises the four
modes in which diatoms are reproduced by means of auxospores or
zygosperms : — (i) Two products of conjugation are formed by the union
of the contents of two distinct individuals; (2) a similar process results
in the formation of a single product of the same nature ; (3) a single
act of conjugation (production of auxospore) takes place between two
portions of the contents of the same individual ; (4) two such acts of
conjugation take place simultaneously between different portions of the
contents of the same individual. In all cases the formation of a new in-
dividual is completed by the simple division of the product of union

424 PROTOPHYTA

{auxospore or zygosperm) into two symmetrical halves with or without
the intervention of a period of rest.

Still another mode of reproduction is described by Count Castracane
and by some other observers, in Mastogloia (Thw.) and a few other
genera, in the production of endogenous spores within the frustules.

It will be seen that, notwithstanding the great abundance of diatoms,
some important points in their life-history still remain unsettled. On
the minuter details of the modes of reproduction, the spontaneous
motion of diatoms and its causes, the structure of the siliceous cell-wall,
and the chemical and physical properties of diatomin, the reader is
referred to the very extensive literature of the subject ; only the most
important memoirs are referred to below. The number of described
species certainly exceeds 10,000 ; but this has been unduly increased
by want of attention to the necessary variations in size in the same
species. Not unfrequently diatoms form a gelatinous yellow scum
on the surface of the water, or completely encrust submerged algae
and other water-plants; they abound on the surface of wet walls
and rocks, and are not unfrequently present in the air. Some species
are cosmopolitan ; the marine forms are especially remarkable for their
size and beauty. Various deposits found on the surface of the globe,
often of very considerable thickness, known as tripoli, ' Kieselguhr,'
&c., consist almost entirely of the fossilised siliceous shells of diatoms,
and they enter largely into the composition of a variety of earths
used for manufacturing purposes. In some countries, such as China,
Japan, Siberia, Lapland, &c., they form, cemented together by salts
of lime, the edible earths which are mixed with meal to make a kind
of flour. They occur also in large quantities in guano.

As has already been stated, the position of the Diatomaceae in the
natural system is a point on which there has been much controversy.
Those who regard the mode of reproduction already described as a true
process of conjugation place them in the class of Conjugatae, near to the
Desmidiaceae, with which family they present many points of resemblance
in external form, phenomena of spontaneous movement, &c. ; and it is
possible that the diatoms may be derived from the desmids by retro-
gressive metamorphosis. But we are, on the whole, disposed to the
conclusion that they have a totally different origin ; their very wide dis-
tribution in time and space, the sharp differentiation of the family, and
the enormous number of species, favouring the view that they represent
a comparatively small ascent from an archaic type which has never
attained any higher degree of development.

Illustrative genera : — Eunotia (Ehrb.), Diatoma (DC.), Melosira
(Ag.), Gomphonema (Ag.), Navicula (Bory), Rhabdonema (Ktz.),

ft

DIATOMACE&

425

FIG. 357 — Diatomaceae : A, Eunotia monodon Ehrb. ; .Z?, Tricerattum Favus Ehrb. ; C, Surirelia
splendida Ktz. ; /), SynedraArcus Ktz. ; ^, Naviciila rhomboides Ehrb. ; ^', Pleurosigma lacustre
Sm. ; G, Cocco-nema lanceolatnm Ehrb. ; //, Meridian constrictnm Rlfs. ; /, Achnanthes breiripes
Ag. ; JiT, Diatvma elongatum Ag. (variously magnified). (After W. Smith.)

426 PROTOPHYTA

Nitzschia (Hass.), Pleurosigma (W. Sm.), Achnanthes (Bory), Meridion
(Leibl.), Biddulphia (Gray), Amphora (Ehrb.), Campylodiscus (Ehrb.),
Cymbella (Ag.), Epithemia (Breb.), Pinnularia (Ehrb)., Stauroneis
(Ehrb.), Surirella (Turp.)", Synedra (Ehrb.), Mastogloia (Thw.),
Amphipleura (Ktz.), Fragillaria (Lyng.), Tabellaria (Ehrb.), Aulacodiscus
(Ehrb.), Coscinodiscus (Ehrb.), Licmophora (Ag.).

LITERATURE.

Agarclh — Conspectus Diatomacearum, 1830.

Ehrenberg —Die Infusionsthierchen, 1838.

Kiitzing — Die kieselschaligen Bacillarien, 1844.

Rabenhorst— Die Slisswasser-Diatomaceen Deutschlands, 1853.

Rylands — (Marking of diatoms) Quart. Journ. Micr. Sc., 1860, p. 25.

Grunow— Oesterreichische Diatomaceen, 1862.

Heiberg— Kritisk Oversigt Danske Diatomaceer, 1863.

Cleve— Svenska och Norska Diatomaceer, 1868.

W. Smith— Synopsis of British Diatomacese, 1872.

Hamilton L. Smith — Conspectus of the Diatomaceae, Lens, 1873, P- 63.

Habirshaw — Catalogue of the Diatomaceae, 1877..

Mereschkowsky- (Movements of diatoms) Bot. Zeit., 1880, p. 520.

Hallier — Untersuchungen iiber Diatomeen, 1880.

Brun— Diatomacees des Alpes, 1880.

Van Heurck —Synopsis des Diatomacees de Belgique, 1881.

Pfitzer — Die Bacillariaceen, in Schenk's Handbuch der Botanik, ii., 1882.

Castracane — Diatoihaceae of the Challenger Expedition, 1886.

Also numerous papers by Wallich, Thwaites, Carter, Liiders, Millardet and Kraus,
Schultze, Schmitz, Askenasy, Borzcow, Cox, Schaarschmidt, O. Miiller, Flogel,
Schiitt, Nelson and Karop, Deby, Brun, Cleve, Grunow, Janisch, F. W. Lewis,
Greville, O'Meara, Petit, Gregory, Donkin, Ralfs, Walker-Arnott, Castracane,
Brebisson, Kitton, Leuduger Fortmorel, Pfitzer, Rattray, Yan Heurck, Grove and
Sturt, and others.

For the preparation of diatoms as microscopic objects see H. L. Smith, Lens,
1873, p. 209 ; Kitton, Science Gossip, 1877. For detailed bibliography see Deby
and Kitton, Bibliography of the Microscope, pt. 3, the Diatomaceae, 1882.

Class XXVII.— Cyanophyceae.

In the Cyanophyceae or Phycochromaceae are included all those
unicellular chlorophyllous organisms in which the cell-sap is uniformly
pervaded by a blue-green pigment which masks the pure green of the
chlorophyll. This pigment can be separated, giving, in its aqueous
solution, a beautiful blue colour in transmitted, a blood-red in reflected

CYANOPHYCEAE 427

light, and is known as phycocyanin. This colour is, in a few cases, re-
placed by a red, and, in some Scytonemaceae, by a brown endochrome,
the scytonemin of Nageli.

Although the Cyanophyceae are described as unicellular, this term
must be used with some limitation in the sense employed with respect
to the Protococcoideae, in comparison with which some of the blue-
green algae display greater differentiation in their vegetative structure.
In several families, notably the Oscillariaceae and Rivulariaceae, the
protoplasm of the very long filament is broken up transversely into a
large number of imperfect cells known as pseudocysts, which are, how-
ever, never invested with a true cellulose cell-wall. In the Nostocaceae,
the breaking up of the filament into cells is much more complete ; but
even here it is doubtful whether the very thin membrane in which they
are invested is composed of true cellulose. It displays the strongest
tendency to deliquesce into a hyaline jelly, and, not unfrequently, as in
the Scytonemaceae and some Nostocaceae, this gelatinous envelope
becomes strongly coloured. Chromatophores with enclosed pyrenoids
and nuclei are stated to have been detected in some species ; while
other authorities assert that neither starch nor a true nucleus is found
in the Cyanophyceae.

Multiplication by ciliated zoospores is, with a few doubtful excep-
tions, unknown in the Cyanophyceae. The ordinary mode of propaga-
tion in the lower families is by simple cell-division. Quiescent resting-
spores or cysts, with thicker cell- walls, are also produced in several
families. In the filiform orders, portions of the filament known as
hormogones, consisting of a varying number of pseudocysts, become
detached ; these hormogones are endowed for a time with a power of
spontaneous motion, after which they come to rest, and develop into
new filaments. In the Oscillariaceae this power of motion extends to
the entire individual. In the Rivulariaceae, Scytonemaceae, and Nosto-
caceae, a further differentiation is exhibited, of special cells within the
filament known as heterocysts ; but their function is unknown.

The life-history of many of the Cyanophyceae is still but imperfectly
known, and their classification into families is very obscure. Some of
those who have most closely investigated their structure and develop-
ment are of opinion that a large number of the apparently distinct forms
are but stages in the development of the same pleomorphic organism,
often really belonging to a higher type. This will be further discussed
under the separate families. They may be conveniently divided into
two groups : the Chroococcacece, which are strictly unicellular, and the
Nostochinea, embracing those families in which the aggregation of cells
or pseudocysts assumes more or less of a filiform character.

428 PROTOPHYTA

Sub-class 1. — Nostochinese.

It is convenient to group together under this head those families of
Cyanophyceae, the Nostocacetz, Rivulariacea, Scytonemacea, and Osdl-
lariacece, which are characterised by the individual consisting of a cel-
lular or pseudocellular filament, reproduced by motile hormogones, and,
in some of the families, forming heterocysts.

i Borzi, who has closely examined the structure and life-history of the
Nostochineae, considers that they display only a rudimentary cell-structure.
The cell-wall is extremely thin, is inseparable from the contained proto-
plasm, and not sharply differentiated from it in its chemical reactions.
The cells do not contain true starch, its place being taken, in spores
and in the constituent elements of the hormogones, by a substance to
which he gives the name cyanophycin — of a granular nature, apparently
formed from the substance of the cell-wall, possibly a carbohydrate, and
identical with the gelatinous substance of which the sheath which
encloses the filaments is composed. The only indication of a nucleus
is a local fragmentation and concentration of proteinaceous matter.
Borzi states that in all the families of Nostochineae the cells of a fila-
ment are in communication with one another by pores in their transverse
walls, through which pass strings of protoplasm, or of a substance allied
to cellulose. When heterocysts are about to be formed, this intercellular
communication is suspended, and the pores are closed by a thickening
of the cyanophycin or other cell-contents. In the Nostocaceae, Scyto-
nemaceae, and Rivulariaceae, the filaments are enclosed in a gelatinous
sheath, which is much thinner in the Oscillariaceae, and altogether want-
ing in Borzia (Cohn). This mucilaginous sheath may be continuous or
septated, and may be composed of a single layer or of several ; in the
latter case it not unfrequently assumes the form of a funnel at the end
of the filament. Gomont differs to a certain extent from these conclu-
sions, previous observers having, according to him, confounded the
envelope proper of the cell with the mucilaginous sheath of the trichome.
By the action of chromic acid he was able to separate the one from the
other, and finds the very thin perfectly transparent envelope proper of
the cell to possess properties intermediate between those of "fungus-
cellulose and of vegetable cutin. Bornet and Flahault call the string
of cells or pseudocysts the trichome^ the trichome with its envelope the
filament.

When in a purely vegetative condition, all the cells of a filament are
alike in form and size, and multiply by repeated bipartition. Scott and
Wille have been able to demonstrate the presence of a nucleus in

CYANOPHYCE^ 429

several species of Oscillaria (Bosc.) and Tolypothrix (Ktz.). The
hormogones consist of a number of cells, often considerable, but usually
variable in the same species. Only in a few species is the number
constant, and then usually two, three, or four. Their contents are
generally of a yellowish -green colour. According to Borzi, the hormo-
gones of the Nostochineae are of two kinds, straight and spiral. The
latter kind occur only in the Oscillariacese, and are confined to the
terrestrial species of Oscillaria, Microcoleus (Desm.), and Spirulina
(Lk.). They are invested in a thin gelatinous sheath, and their movement
is of a spiral nature, lasting much longer than that of the straight
hormogones. These latter occur in all the families ; they are not in-
vested in a gelatinous sheath ; their motion is rectilinear and of short
duration. The cells have excessively thin cell-walls, and contain
abundance of cyanophycin, slightly coloured by phycocyanin. The
cells of the hormogones are in communication with one another in the
same way as the ordinary vegetative cells.

The spores of Nostoc and other Nostochineae are, according to
Borzi, formed as follows. The cells which become transformed into
spores cease dividing transversely and increase somewhat in size. The
gelification of the outer layer of the cell-walls ceases at the same time
and a new cell is formed inside the old one by a process of rejuvenes-
cence, the wall of the mother-cell ultimately disappearing altogether.
The membrane of the spores thus constituted is formed out of their
protoplasmic contents, and is homogeneous, without differentiation into
exospore and endospore. The spore is, therefore, not homological with
those of the higher Cryptogams, but is regarded by Borzi as partaking
more of the nature of a cyst. Gomont, on the other hand, finds that
the spores of the Nostochineae, which are always the result of the
encysting of ordinary vegetative cells, possess a distinct exospore and
endospore, the former being again composed of two distinct layers, the
outer of which is frequently warty or otherwise marked.

LITERATURE.

Thuret— Mem. Soc. Sc. Nat. Cherbourg, 1857, p. 29 ; and Classification des Nosto-

chinees, 1875.

De Bary — Beitr. zur Kenntniss d. Nostocaceen, Flora, 1863, pp. 553 and 577.
Bornet and Thuret — Notes Algologiques, 1876-1880 (especially Fasc. ii.).
Borzi— Nuov. Giorn. Bot. Ital., 1882, pp. 272 and 384 ; and Malpighia, 1886.
Bornet and Flahault— Ann. Sc. Nat., iii.-vii., 1886-1888; and Mem. Soc. Sc. Nat.

Cherbourg, 1887, p.,195-
Gomont— Morot's Journ. de Bot., 1888, p. 43; and Bull. Soc. Bot. France, 1888,

p. 204.

43o PROTOPHYTA

ORDER i. — NOSTOCACE/E.

The Nostocaceae are distinguished from all the other families of fila-
mentous Cyanophyceae by the less close connection with one another of
the pseudocysts of which the filament is composed, giving it always more
or less of a moniliform or necklace-like appearance. In most of the
genera these pseudocysts are spherical or elliptical ; but in Nodularia
(Mert.) they are disc-shaped, and more closely connected with one
another than in the other genera. The extent to which the filaments
are enveloped in mucilage varies greatly. In some genera (Nodularia)
each filament is enclosed in a distinct hyaline sheath. In others
(Anabsena, Bory, Aphanizomenon, Morr., Sphaerozyga, Ag., Cvlindro-
spermum, Rlfs.) this sheath is obscure or wanting ; in Aulosira (Kirch.)
the filaments are either naked, or enclosed in a dry membranous sheath.
In most species of Nostoc (Vauch.) a single filament or a number of
filaments are enclosed in a hyaline jelly, often of considerable size and
definite outline, formed from the more or less complete coalescence of

the separate sheaths, which can
still sometimes be indistinctly
made out. Such a jelly-like mass,
which sometimes floats freely in
the water of bog-pools, but is
more often found on damp soil, is
sometimes called a ' thallus ' or

FIG. 358.-.V^jr^=L. (natural size). < fo^, jt may yary in ^ fj.Qm

0*2 mm. to that of a small plum ;

is often of a green, violet, or blue colour, and, in the larger terrestrial
species, the outer layers of the integument are more or less hardened,
forming what is known as a ' periderrn.'

The Nostocacese display no differentiation of the two extremities of
filament. In nearly all the genera some of the cells are here and there
replaced by heterocysts — cells incapable of further division, of a slightly
larger diameter, and with a somewhat thicker cell-wall, which is often
yellow, the green protoplasmic endochrome being replaced by a watery
colourless cell-sap. These heterocysts, the function of which is unknown,
may be terminal, basal, or intercalary. Others of the cells, always in this
case intercalary, are, in most species, replaced by resting-spores, also dis-
tinguished from the ordinary cells by their larger size and thicker cell-
wall, but containing a green endochrome. They are often formed more
or less in connection with the heterocysts. In Cylindrospermum the
terminal cells of the filaments become heterocysts, and the spores, some-

CYANOPHYCEJE

43*

times associated in chains, are formed immediately beneath them. Thfe
cell-wall of the resting-spores is often coloured yellow or brown, and is
sometimes warty. After a period of rest they germinate by the bursting
of the cell-wall and protrusion of the protoplasm. The hormogones are
strings of from four to eight or twelve ordinary cells, situated between
two heterocysts, which detach themselves from the rest of the filament,
escape from their mucilaginous envelope, move about with a creeping
motion, then come to rest, and develop into new individuals.

Bornet describes the motion of the hormogones of Nostoc as a
creeping movement along a solid substratum at a rate of i p (*ooi mm.)
per second. After some hours they come to rest, large refringent
globules which had previously been formed in the cells disappear, and
they assume the appearance of ordinary filaments. Sometimes they

FIG. 360. — A nabcena jlos-aqu<z Fr. ( x 400).
(After Cooke.)

FIG. 359. — N. hyalinum Benn. A, 'frond' (x 200) ;
/>', portion of trichome with heterocyst, c ( X 600).
(From nature.)

invest themselves with a mucilaginous sheath, and are transformed
directly into spores, but usually the filament lengthens, displaying at the
same time more or less sinuosity. The heterocysts do not appear at
regular intervals. A new filament is thus formed altogether resembling
those which spring directly from the germination of the spores. Once
formed, it is subject to intermittent periods of growth, a second genera-
tion of spores, with thinner cell-walls, being sometimes formed after the
first. In other cases the filament springing directly from a hormogone
assumes a zigzag form, in consequence of some of the cells dividing in
the transverse, others, in the longitudinal direction. In N. muscorum
(Ag.) all the cells except the heterocysts are sometimes transformed into
spores. The spores will occasionally germinate while still within the
' frond.' The filaments of Nostoc are ultimately serpentine, and often

432

PROTOPHYTA

intricately interwoven, owing to the heterocysts maintaining their position
when once formed, while the portions of the filament between them
continue to lengthen by cell-division.

Most of the Nostocaceae inhabit fresh, usually stagnant, water, bog-
pools, &c. ; a very few grow in salt water. Several species of Anabcena
Bory, Aphanizomenon Morr., and some other genera, frequently collect
as a bright bluish-green scum on the surface of bog-pools ; Aphanizo-
menon flos-aquae (Rlfs.) is one of the organisms which contribute to the
phenomenon know as the ' breaking of the meres.' The
decay of species of Anabaena has a large share in causing
the foul odour and injurious properties of stagnant water.
Of the numerous species of Nostoc Vauch., a few
only swim freely in water ; these are usually minute with

a colourless * thallus ' more
or less nearly spherical and
distinctly lamellated, with
a spontaneous power of
active motion in the water.
The larger number are
terrestrial, growing on wet
rocks, among moss on
damp soil, or even on the
comparatively dry ground,
forming conspicuous jelly-
like masses, often as much
as from one to two inches
in diameter, usually of a
green, yellow, brown, or
sometimes red colour, the
'frond' enclosing a large
number of bright blue-
green filaments (fig. 358). It is not uncommon for other chlorophyl-
lous protophytes or algae, the mycele of fungi, and the protoneme
of mosses, to become enclosed, and even to continue growing, within
their gelatinous envelope. Species of Nostoc and Anabaena are found
in hot springs, and several species of the same genera are frequently
to be met with within the cells of living aquatic or land plants, where
they carry on an epiphytic existence (see pp. 28, 165, 171). They
occur with especial frequency in Lemna, causing yellow spots in the
leaves.

Isocystis Bzi. is probably the simplest form of the Nostocaceae. It
consists of delicate moniliform filaments, which do not form colonies, but

FIG. 361. — Aphani-
zomenonJJos-aqucE
Morr., with spore
( x 400). (After
Cooke.)

FIG. 362. — Cylindrospermnm macro-
spermutn Ktz., with heterocysts
and spores ( x 400). (After Cooke.)

CYANOPHYCE^E 433

float freely on the surface of the water, solitary or in interwoven masses,
forming but little mucilage, and destitute of heterocysts.

Hansgirg (Bot. Centralbl., xxii. and xxiii., 1885) regards the genera
Nostoc, Anabaena, Cylindrospermum, and Sphaerozyga as stages of
development — analogous to certain zoogloea-conditions of the Schizo-
mycetes— of various species belonging to the Oscillariaceae, Rivulariaceae,
and Scytonemaceae. The relationship of Nostoc with Drilosiphon will
be alluded to under this last family (see p. 440). The Nostocaceae appear
also to approach the Schizomycetes through Leuconostoc (Van Tiegh.).

Among the Nostocaceae are included, in addition to the genera
already mentioned, Nodularia (Mert)., Cylindrospermum (Ktz.), Sphae-
rozyga (Ag.), and Aulosira (Kirch.).

LITERATURE.

Meneghini — Monogr. Nostoc. Ital. , 1843.

Thuret— Mem. Soc. Sc. Nat. Cherbourg, 1857, p. 23; Ann. Sc. Nat., 1875, p. 372-

Janczewski — Ann. Sc. Nat., 1874, p. 123.

Bornet and Thuret— Notes Algol., fasc. i., pp. 2-3 ; fasc. ii., pp. 78-132.

Borzl— Flora, 1878, p. 465 ; and Nuov. Giorn. Bot. Ital., 1878, p. 236.

Fischer — Beitr. zur Kenntniss der Nostocaceen, 1853.

ORDER 2. — RIVULARIACE^:.

In the Rivulariaceae — including also the Calotrichaceae — the cells
or pseudocysts of which each filament is composed are not connected
together in a necklace-like form, but constitute a continuous thread
divided by transverse septa which are exceedingly thin and often
scarcely perceptible. Many of the species are extremely minute, the
individual filaments being quite microscopic, and grow attached in tufts
to a solid substratum, some water-plant or floating body, from which they
radiate in a star-shaped manner, forming small green discs or cushions,
often imbedded in copious mucilage. Each filament displays a distinct
differentiation of the two apices, the distal extremity being elongated and
attenuated into a hyaline hair, while at the base a portion is marked off
into a more or less globular colourless basilar cell, the rudimentary cell-
division being exhibited by the portion intermediate between the basilar
cell and the terminal hyaline hair. The terminal hair is, according to
Gomont, in perfect continuity with the rest of the true membrane of the
filament, and is distinguished only by having fewer transverse septa, and
by the entire absence of granular protoplasm. The outer layers of the
walls of the filaments have a very strong tendency to become transformed
into mucilage, from which is formed not only the copious jelly in which

F F

434

PROTOPHYTA

the colony is usually invested, but in most species also a separate delicate
membranous sheath to each individual, often of a yellowish colour, which
ultimately becomes open at the apex. In Microchaste diplosiphon
(Gomont, Bull. Soc. Bot. France, 1885, p. 209) this sheath is double.
The common gelatinous envelope of the
colony sometimes becomes at length calca-
reous. In other species, which float on the
surface of the water, the development of
mucilage is much feebler.

The filaments of the Rivulariacese branch
in a peculiar way. A small portion of the
green tract between the basilar cell and the ter-
minal bristle becomes rounded off, loses its
endochrome, and forms a heterocyst resembling
the basilar cell. This heterocyst now assumes
the part of a basilar cell ; the terminal por-
tion of the filament beyond it detaches itself,
and applies itself laterally to the heterocyst,

FIG. ^.—Rivularia^olyotis Hauck. a, invested in its gelatinous envelope (natural size).
6, vertical section (x I2). c, filament ( x 150). (After Hauck.)

forming a ' pseudo-ramulus ' or false branch ; the original filament then
develops a new apical portion in a direct line above the heterocyst.
Heterocysts have not yet been observed in all the genera ; they some-
times occur interstitially in the filament without giving rise to a pseudo-
ramulus ; their function is obscure. The terminal hyaline bristle is of

CYANOPHYCE^E

only temporary duration ; when it
disappears it leaves the membra-
nous sheath open at the extremity.
This is especially well seen in
Calothrix (Ag.).

The ordinary mode of multi-
plication of the Rivulariaceae is
by means of hormogones, frag-
ments of the green portion
which become detached from the
rest of the filament, escape from
the gelatinous envelope, move
about with a creeping motion,
eventually come to rest, invest
themselves with a gelatinous
sheath, and develop into a new
filament in which the differenti-
ation of the basal and apical
extremities is soon manifested.
The formation of hormogones
is confined to the lower and
central portions of the filament,
and commences only after the
disappearance of the terminal
hyaline hair. They vary greatly
in length, being composed of
from two to fifty pseudocysts.
When fully formed, they glide
slowly out of the sheath, several
often attached to one another.
At the period of detachment of
the hormogones the whole fila-
ment displays a slow movement ;
otherwise it is quiescent, the
power of motion which in the
Oscillariacese belongs to the entire
filament being in the Rivulariaceae
restricted to the hormogones.
Beck (Verhandl. zool.-bot. Gesell.
Wien, 1886, p. 47) describes a
peculiar mode of formation of the
hormogones in Glceotrichia natans

FIG. 364. — Calothrix Crustacea Thur. (x 160).
(After Bornet.)

436

PROTOPHYTA

(Thur.) while still within the sheath, the cell-contents passing from a
heterocyst into the basal cell of a hormogone.

Multiplication by quiescent resting-spores has been observed in some
species of Rivulariaceae. The lower portion of the green part of a fila-
ment immediately above the basilar cell is transformed into an elliptical
thick-walled spore, which escapes from its investing membrane, and,
after, a period of rest, either develops directly into a new filament, or

breaks up into a number of hormo-
gones. The spores of Glceotrichia
punctulata (Thur.) are rough.
Under the name ' conids ' Bornet
and Flahault also describe special
propagative cells which become
detached from the lower part of the
filament.

By far the larger number of
species of Rivulariaceae grow in
fresh water, especially stagnant, also
on damp soil and on wet rocks.
The species of the typical genus
Rivularia Roth are especially
abundant in both running and
standing water ; R. fluitans (Cohn,
Hedwigia, 1878, pp. i and 33) floats
free on the water, forming a blue-
green scum which enters largely
into the composition of what is
known as ' flos aquae.' Some species
have a red tinge. Calothrix .^Ag.,
though placed by Rabenhorst among
the Scytonemaceae, has all the cha-
racteristics of the Rivulariaceae.
The filaments of some species are
comparatively thick, as much as

o'oi mm. in diameter, and are invested in a copious, often coloured,
mucilaginous sheath. Microchcete Thur. is nearly allied to Calothrix,
as is Glceotrichia Ag. to Rivularia. Several species of Rivularia
and Calothrix grow in salt or brackish water, and Isactis Thur. is ex-
clusively marine. In Hormactis Thur., which is also marine, the fila-
ments are curved in a serpentine manner, and this character, together
with the interstitial heterocysts, appears to indicate an approach to the
Nostocaceae. Other genera included in the Rivulariaceae are Leptoch^ete

FIG. 365. — 1 sactis plana Thur. (x 160).
(After Bornet.)

CYANOPHYCE& 437

(Bzl), Amphithrix (Ktz.), Dichothrix (Zanard.), Sacconema (Bzi.),
Brachytrichia (Zan.), and Polythrix (Zan.), the last being marine.

Hansgirg (Bot. Centralblatt, xxii. and xxiii., 1885) considers the
genera ordinarily placed under Rivulariaceae as being higher develop-
ments of organisms belonging to the Oscillariaceae.

LITERATURE.

De Bary— Flora, 1863, p. 577.
Bornet and Thuret — Notes Algol., fasc. i., 1876, pp. v.-viii. ; and fasc. ii. , 1880,

PP- I57-I7S.

Bornet and Thuret— Etud. Phycol., 1878, pp. 1-6.
Bornet and Flahault— Ann. Sc. Nat., iii. (1886), p. 337; and iv. (1886), p. 341.

ORDER 3. — SCYTONEMACEAE
(including STIGONEME.E and SIROSIPHONE^E).

The Scytonemaceae resemble the Rivulariaceae in consisting of
branched filaments, often comparatively stout, enclosed, either singly or
in numbers, in a mucilaginous sheath ; but differ from that family in dis-
playing no differentiation of the two extremities. The filament termi-
nates at each end in a large thin-walled apical cell, by the repeated
division of which the greater part of the growth in length takes place.
The filaments display no oscillation or other spontaneous motion. The
mucilaginous sheath which invests one or more filaments is of consider-
able thickness, except over the apical cells, where it is very thin ; else-
where it is generally lamellated, the lamellae decreasing in number
towards the apex, which gives the appearance of a number of funnels
inserted one in another. It is often coloured by a deep yellow or brown
pigment known as scytonemin, and becomes dry and pulverulent with
age, Jbut in younger filaments the sheath is sometimes altogether wanting.
The filaments are not septated laterally, but the contents are divided
into * gonids ' or pseudocysts, of a spherical or elliptical form, and arranged
in a single row in the thinner, often in two parallel rows in portions of the
thicker, filaments. These pseudocysts are at first green, but frequently
become subsequently dark brown ; and the filament exterior to the
pseudocysts is commonly filled by endochrome coloured brown by
scytonemin ; the entire plant being therefore distinguished by its brown
or orange colour. In Tolypothrix (Ktz.) and Plectonema (Thur.) the
filaments generally retain permanently a green colour.

The Scytonemaceae' may multiply by the individual filaments,
enclosed in a common sheath, which have no genetic connection with
one another, escaping separately from their sheath, and then investing
themselves in a new mucilaginous envelope. But the ordinary mode of

438

PROTOPHYTA

propagation is either by resting-spores or by hormogones. In the former
case, at the end of the season of growth, the disc-shaped pseudocysts
towards the end of a filament assume a roundish or ovate form, the gela-
tinous sheath disappears, and the spores thus formed remain for a time
united together in masses. These resting-spores are capable of resisting a
high degree of cold and drought ; they germinate after a period of rest,
when the membrane bursts transversely. In the formation of hormogones
the sheath also becomes absorbed, beginning from the apical cell, and

the filament breaks up into
a number of hormogones,
each consisting of many
pseudocysts. In the Sti-
gonemeae the hormogones
are formed only in the
lateral branches, which con-
tain only a single row of
pseudocysts. The hormo-
gones move slowly in the
water in a straight line ; in
some cases an entire fila-
ment may be converted
into a motile hormogone.
During germination the
hormogone, enclosed in a
delicate transparent mucila-
ginous sheath, breaks up
into portions of various
lengths, or it becomes a new
individual without breaking
up ; and at this period one
of the apical pseudocysts
usually becomes a hetero-
cyst.

The branching of the Scytonemaceae takes place in two different
ways, characteristic of the two sub-orders into which they are divided—
the Scytoneme<z and the Sirosiphonece. In the Scytonemeae, which in-
clude the genera Scytonema (Ag.), Petalonema (Berk.), Tolypothrix
(Ktz.), Plectonema (Thur.), and Drilosiphon (KA.z.\ pseudo-ramuli are
formed somewhat in the same way as in Rivularia, but the branches are
much stouter, and stand out at right angles to the main axis. In
Scytonema Ag. two contiguous pseudocysts separate at indefinite spots
on the filament, and each of these then acts as the terminal pseudocyst

FIG. 366. - Stigonema minutum Hass. A , outline of fila-
ment ( x 100) ; B, portion of primary filament ( x 200) ;
C, ditto with branch ( x 200). (From nature.)

CYANOPHYCE&

439

to a lateral branch ; the branches therefore spring in pairs at a right
angle from the main axis. Thick-walled heterocysts may be formed
at any spot in the filament. In Tolypothrix Ktz. the false branches
spring singly from beneath heterocysts. In the Sirosiphoneae, including
Stigonema (Ag.), Sirosiphon (Ktz.), Fischera (Schw.), Capsosira (Ktz.),
Hapalosiphon (Nag.), Mastigocladus (Cohn), and Mastigocoleus
(Lagerh.), the formation of a false branch is preceded by a change in

FIG. 367. — Hapalo siphon byssoideus Kirch, (x 200). (From nature.)

the direction of cell-division. Two or three contiguous pseudocysts in
an older portion of the filament divide in a direction parallel to the
axis of growth of the filament, and one of the new pseudocysts thus
formed now becomes the basal pseudocyst of a lateral branch, which
generally consists of a single row of pseudocysts at right angles to the
axis. In Plectonema Thur. the branches protrude outside the mucila-
ginous sheath. Heterocysts are formed in all parts of the filament, but
their function is unknown.

440 PROTOPHYTA

Coleodesmium Bzi. appears to be one of the simplest forms of the
Scytonemaceae. No pseudo-ramuli are formed ; the filaments increase
by fission only, and a number remain united in a bundle within a
common envelope. Mazcza (Bornet, Bull. Soc. Bot. France, 1881,
p. 287) is, on the other hand, a genus in which the development is
carried to its highest point. The gelatinous ' fronds ' are about 25 mm.
in diameter ; the heterocysts are borne on pedicels consisting of from
one to three cells, and the whole appearance is that of a Rivularia, the
filaments being immersed in a homogeneous jelly, and spreading from
a central spot. No distinct sheath has been observed, nor any resting-
spores or hormogones. In Petalonema Berk, the mucilaginous sheath
forms a kind of broad coloured wing to the filament. Mastigocoleus
(Lagerheim, Notarisia, 1886, p. 65) is a marine genus growing attached
to the shells of molluscs, with both terminal and lateral heterocysts ;
the filament sometimes ends in a hair, as in the Rivulariaceae. Drilo-
siphon Julianus Ktz., frequent on the damp walls of greenhouses, is
characterised by an outer calcareous sheath, and is a remarkably pleo-
morphic organism. According to Zukal (Oesterr. Bot. Zeitschr., 1883,
p. 73) it forms two kinds of hormogones, and displays a kind of alterna-
tion of generations. The ordinary hormogones produce only more and
more slender filaments, which gradually assume a moniliform character,
and are then known as Nostoc parietinum (Rabh.). Eventually the
cells of these nostoc-filaments separate, and assume the character of
an Aphanocapsa, or, in other cases, become the organism known as
Glceocapsa fenestralis (Ktz.) ; or very slender filaments are produced,
constituting the Leptothrix parasitica and muralis (Ktz.), which forms
are distinctly connected genetically with Drilosiphon. These leptothrix-
filaments may again break up into vibrio- and bacillus-forms. The
second kind of hormogone has a fusiform shape, and consists usually of
from four to eight pseudocysts. It may remain dormant for a time,
and, on germinating, reproduces the ordinary thick filaments.

Wille (Ber. Deutsch. Bot. Gesell., 1883, p. 243) and Scott (Journ.
Linn. Soc., xxiv., 1887, p. 188) have determined the presence of a cell-
nucleus in Tolypothrix. Wille states also that in Stigonema compactum
(Kirch.) the necklace-like pseudocysts are in direct communication
with one another through perforations in their cell -walls. AVhen this
species passes into the Glceocapsa-condition, the perforations disappear,
in consequence of the gelification of the common sheath, and the
separate cells then carry on their existence as distinct individuals.
Under the name Tolypothrix amphibia, Zopf (Ber. Deutsch. Bot.
Gesell., 1883, p. 319) describes an organism having both an aerial and
an aquatic form, the latter being a true Tolypothrix with its filaments

CYANOPHYCE^E 441

enclosed in sheaths and breaking up into hormogones, from which is
derived the aerial form with the nature of a Chroococcus, and dividing
in three directions.

Rabenhorst and Cooke regard Stigonema, and the latter authority
also Hapalosiphon, as genera of lichens ; and Bornet and Flahault
state that several organisms described as species of Sirosiphon and
Stigonema are really lichens in a more or less advanced stage of deve-
lopment. Hansgirg (Oesterr. Bot. Zeitschr., 1884, and Bot. Centralbl.,
xxii. & xxiii., 1885) considers the genera placed under Scytonemeae to be
the highest forms of development of various organisms hitherto mostly
placed under Oscillariacese. In the same way, from Tolypothrix and
Scytonema may arise, by further development, the corresponding forms
of Hapalosiphon, Mastigocladus, Sirosiphon, Stigonema, Fischera, and
other genera usually placed under Sirosiphoneae.

With the exception of Mastigocoleus, the Scytonemaceae are found
only in fresh water, in bog-pools, or very commonly on wet rocks or
trunks of trees, or among moss. They may form mats of considerable
thickness, but the individual filaments, including the sheath, seldom
exceed o'04-o*c>5 mm. in thickness. Several Scytonemaceae are known
to enter into the composition of lichens (see fig. 2790.)

LITERATURE.

Bornet— Notes Algol., fasc. I, 1876, pp. iv.-v. ; fasc. 2, 1880, pp. 135-156.
Bornet and Flahault — Ann. Sc. Nat., v., 1887, p. 51.

ORDER 4. — OSCILLARIACESE (including CHAM^SIPHONACE^E).

The Oscillariaceae or Oscillatorieae, in which the Lyngbyeae are also
included, consist of delicate blue-green threads, occurring singly or in
large floating masses in fresh running, or more abundantly in stagnant,
less often in salt, water. The filaments are cylindrical and unbranched,
straight, or (Oscillaria princeps, Vauch.) with the terminal portion bent
at an obtuse angle with the rest of the filament ; in Spirulina (Lk.) the
whole filament is coiled in a corkscrew-like manner. The filament is
divided by very delicate transverse septa into disc-shaped pseudocysts ;
there is no differentiation between the two extremities. The cell-wall has
the property of transforming its outer layers into copious mucilage, which
forms a gelatinous sheath investing either single filaments, as in Lyngbya
(Ag.)and Symploca ('Ktz.), or a number of filaments, as in Inactis (Ktz.)
and Microcoleus (Desm.). In most species of Oscillaria (Bosc.) and
Spirulina a distinct sheath is either wanting or it is extremely thin and
delicate, but the filaments are often imbedded in structureless jelly.

442

PROTOPHYTA

The blue-green colour of phycocyanin is sometimes replaced by a red
or violet pigment. Scott finds a cell-nucleus in several species of
Oscillaria.

The only certainly known mode of multiplication of the Oscillariaceae
is by a filament escaping from its mucilaginous
sheath, and breaking up into hormogones, each
composed of a small number of pseudocysts,
which round themselves off at both ends and
develop into new filaments.

The family derives its name from the
oscillating or wavy motion with which the
filaments are endowed. This consists in a
creeping movement in the direction of the
length of the filament, now backwards and
now forwards, accompanied by a curvature of
the filament and rotation round its own axis ;
but, according to Borzi, this power of motion
is limited to the reproductive period. The
filaments of the Oscillariaceae have a remark-
able power of resistance to both cold and
desiccation, to which they are adapted by the
encysting of the filament and hardening of
the mucilaginous sheath.

The movements of the Oscillariaceae are
greatly influenced by temperature and light,
being much more active in warmth and sun-
shine than in cold and shade, but their cause
is involved in considerable obscurity. Cohn
(Arch. mikr. Anat., 1867, p. 48) observed that
the oscillating movements take place only
when the filament is in contact with a solid
substratum. Siebold (Zeitschr. wiss. Zcol., 1 849,
p. 284) states that if the water in which they
grow is coloured by indigo, the particles collect
round the filaments of Oscillaria up to their
apex, whether they are in motion or not. Some-
A§- times creeping spiral lines of pigment begin to
be formed at both ends of the filament and
meet in the middle, where the particles become heaped up into little balls ;
or sometimes this begins in the middle and advances to both ends. The
mode in which the particles of indigo adhere to the filament and to one
another appears to indicate the excretion of mucilaginous protoplasm.

CYANOPHYCE& 443

Engelmann (Bot. Zeit., 1879, P- 49) claims to have detected this external
secretion in the case of Oscillaria dubia (Ktz.). Zukal compares the
motion of Spirulina to that of a growing tendril, and asserts that it is
intimately connected with the growth of the filament. It consists of a
slow torsion of the entire helix round its own axis, and is the result of
the more rapid growth in length of the filament than of the ideal axis of
growth. If the motion is suddenly interrupted, the filaments become
for a moment quiescent, and then retreat towards the central point of
the movement, forming a dark green lump. Hansgirg, on the other
hand (Sitzber. Bohm. Gesell. Wiss.,see Bot. Centralbl., xii., 1882, p. 361),
considers the twisting and nodding movements to be due, not to the
growth of the filament, but to osmotic changes in the cell-contents ; the
separate cells exhibiting motion when the envelope itself is at rest. He
regards the movements as of the same nature as those of the sarcode in
the pseudopodes of Rhizopods and other Protozoa. The same observer
states further (Bot. Zeit., 1883, p. 831) that in the protoplasm which had
escaped from the broken end of a filament of O. princeps, he has observed

FIG. 369.— Oscillaria princeps Vauch. (x 200). (From nature.)

a number of amoeboid cells from 9 to 12 /j in diameter, nearly spherical
in form, and putting out colourless pseudopodes about twice the length
of the central body, and to these he attributes the motile properties of
the protoplasm. He believes the cause of the oscillating motion to be
that the internal protoplasm takes up water more rapidly, and conse-
quently swells to a greater extent, than the enveloping sheath, causing
the filament, to move slowly backwards and forwards within the sheath.
In those species in which each filament is not invested in a separate
sheath, variations in the turgidity are also brought about by variations
in the endosmotic and exosmotic currents. Finally Schnetzler (Arch.
Sc. Phys. etNat., 1885, p. 164) describes the movements in O. aerugineo-
coerulea (Ktz.) as of six different kinds, viz. : (i) rotation of the filament
or of its segments round its axis ; (2) creeping or gliding over a solid
substratum ; (3) a swimming change of position in the water ; (4) rota-
tion or flexion of the entire filament ; (5) sharp tremblings or concus-
sions ; and (6) a radiating arrangement of the entangled filaments.

Most of the species of the typical genus Oscillaria Bosc. grow in
dense slimy tufts attached to other algge or floating bodies, the filaments
being not more than from 2 to 6 /« in diameter ; in a few species,

444

PROTOPHYTA

such as O. princeps (Vauch.), the diameter is much greater, the separate
filaments, just visible to the naked eye, floating on the surface of the
water. Lyngbya Ag. is distinguished by its property of forming
' persistent cells,' the function of which is not known ; they may possibly
be propagative spores. The species have a much less active motion than
those of Oscillaria, and chiefly inhabit salt or brackish water. Symploca
Ktz. grows in tufts, frequently among grass with the habit of a Rivularia.
In Microcoleus Desm, and Inactis Ktz. a large number of filaments are
enclosed in the same gelatinous sheath.

The genera Chamaesiphon (A. Br.), Clastidium (Kirch.), Cyanocystis

(Bzi.), and Dermocapsa (Crouan) (to
which Thuret adds Xenococcus and
Sphaerogonium, Rostaf.) constitute
Borzi's family of Chamasipkona&a, dis-
tinguished, according to that author,
by the presence of coccogones, propa-
gative cells of the nature of sporanges,
in which conids are formed by repeated

FIG. 370. — Spirulina tenuissima Ktz.
( x 400). (After Cooke.)

FIG. 371. — Lyngbya (estuarii Liebm. (x 2co).
(After Hauck.)

division, the usual number in each coccogone being four, eight, or
sixteen. Clastidium (Jahrhft. vaterl. Naturk. Wiirtemberg, 1880, p. 135)
is characterised by each filament having a terminal bristle. Dermocapsa
and Xenococcus are epiphytic on Catenella, Lyngbya, and other marine
algae. The former genus has been placed among both Florideae and
Fucaceae, owing to its mode of propagation ; D. violacea (Crouan) has
a bright red colour.

Plaxonema Tangl (Sitzber. Akad. Wiss. Wien, 1882) is a fila-
mentous protophyte with the habit of an Oscillaria, but characterised by
the presence of a disc-shaped chromatophore in the blue-green proto-
plasm. Under certain conditions the filaments break up into zoogloea-
like colonies. J3orziaCo\\n (Jahrber. Schles. Vaterl. Cultur, 1883, p. 226)
is a genus of Oscillariaceae with the habit of a bacillus, consisting of

CYANOPHYCEsE

445

short oblong rods, which oscillate slowly and are not enclosed in a gela-
tinous sheath. In B. trilocularis (Cohn) each hormogone is composed
uniformly of three pseudocysts only.

Many of the Oscillariaceae enter largely into the composition of the
blue-green scum seen on the surface of stagnant ditches, &c. Together
with others of the Nostochinese they are said
to have the power of decomposing vegetable
matter, and to this is largely due the foul
stench of stagnant water. In addition to
many species of Lyngbya a few belonging
to other genera grow in salt or brackish
water. Several species of Oscillaria are
found in thermal springs.

The relationship of the genera of
Oscillariacese to one another, and even
to genera at present included in other
families, is still very obscure. Hansgirg
believes that many of the forms described
as species of Chroococcus result from the
breaking up of filaments of Lyngbya ;
while, on the other hand, most of Kiit-
zing's species of Leptothrix, and many
of Oscillaria, may be simply hormogones of species of Rivulariaceae,
Scytonemeae, and Stigonemese, propagating by frequent divisions, and
becoming invested in a more or less thick gelatinous sheath. Many
species of Lyngbya may be only the young stages of development of
those species of Calothrix and Scytonema to which they are found
attached. Oscillaria or Lyngbya antliaria (Hansg.) he now regards as in
reality an Aphanocapsa. The same author further states that in the

FIG. 372. — Symfiioca hydnoides Kt/.
(a, natural size ; b, x 200). (After
Hauck.)

FIG. w^.—Symploca violacea Hauck ( X 280). (After Hauck.)

Lyngbyese and other of the higher families- of Cyanophyceae, nuclei,
pyrenoids, and chromatophores occur, but only when they are in a con-
dition of retrogression from the filiform stale, and are breaking up into
the unicellular condition. Under the name Chroomonas Nordstedtii
Hansgirg describes (Bot. Centralbl., xxiii., 1885, p. 229) a biciliated

446

PROTOPHYTA

organism with blue-green endochrome which he regards as the swarm-
cell condition of a phycochromaceous alga which occurs normally in a
filamentous form, probably as Oscillaria tenuis (Ag.) or O. Frolichii

(Ktz.).

LITERATURE.

Fresenius — Ueb. d. Ban u. d. Leben d. Oscillarieen, 1845.
Braun— Bot. Zeit., 1852, p. 395.

Bornet and Thuret— Notes Algol., fasc. I, pp. iii.-iv.' ; and fasc. 2, pp. 132-135.
Zukal— Oesterr. Bot. Zeitschr., 1880, p. n.

Hansgirg— Oesterr. Bot. Zeitschr., 1884, pp. 313 et seq. ; and Ber. Deutsch. Bot.
Gesell., 1885, p. 14.

Sub-class 2 and ORDER 5. — Chroococcacese.

The Chroococcaceae share with the Schizomycetes the distinction
of being among the lowest forms of vegetable life. The separate
cells are always microscopic, and are filled with a blue-green or violet
endochrome which owes its colour to the phycocyanin dissolved in the
cell-sap ; they contain neither distinct chlorophyll-grains nor starch, nor,
except in Chroodactylon (Hansg.), a distinct nucleus. The cells are either
isolated, or are more often connected together
into colonies by a mucus formed from the
disintegration of the outer layers of the cell-
wall ; they are never united into a filament.
This gelatinous envelope is either colourless and
hyaline, or of a blue, brown, or olive colour,
and is often strongly lamellated. In Chroo-
coccus (Nag.) it is homogeneous and capable of
swelling greatly; in Glceocapsa (Ktz.) it is com-
posed of two successive layers, and becomes
eventually, in some species, crustaceous, and of
a very dark brown or even black colour. 1 he

. . 7 . , j j

internal pseudocysts or gonids are never endowed
with cilia, as in some Protococcaceae, and are

usually quiescent ; but in Microcystis (Ktz.) they have a constant
' swarming ' motion within the hyaline envelope. The entire organism
has usually a power of slow spontaneous motion. Multiplication by
swarm-spores or zoospores is unknown except in the doubtful case
of Merismopedia (Mey.) (Goebel, 'Outlines of Classification,' p. 22).
Resting-spores or cysts (akinetes) are formed in Glceocapsa by the
cells of which a colony is composed investing themselves, while still
within their common gelatinous envelope, in a rough or spiny coat of

FIG. 374.-Stages in the de-

veiopment of ckroococcus

turgidus Nag. (greatly mag-

nified). (After Reinke.)

CYANOPNYCE^E

447

cellulose ; the spiny resting-spores thus formed reproduce the colony by
division after a period of quiescence.

With the above exceptions the only mode of propagation in the
Chroococcaceae is by division — repeated repartition of the cell, which may
take place in one, two, or three directions. This is usually accompanied
by the disappearance of the separate gelatinous envelope of each indi-
vidual cell ; but in Glceocapsa these still remain, and as many as three
or four generations of families may be enclosed within the original
envelope, each surrounded by its own investment. In Chroococcus Nag.
it is not unusual for the individual cells to be entirely isolated within the
common envelope. In Synechococcus Nag. division' takes place in one
direction only, and the derivative cells remain attached to one another

FIG. 375. — Aphanothece microscopica.
Nag. (x 70). (From nature.)

FIG. 376. — Glaeothece granosa Rabh. A, gela
tinous colony (magnified) ; B, cells ( x 250}
(After Cooke.)

in a string * but the attachment is very loose, and soon ceases. In
Merismopedia, Tetrapedia Reinsch., and Glceochcete Lagerh. division
takes place in two directions, the result being the formation of a plate of
cells, often of great regularity. In Chroocoaus, Glceocapsa, Glceothece
Nag., Aphanocapsa Nag., Aphanothece Nag., Microcystis, and most
other genera, division takes place in all three directions. In Clathrocystis
Henf. the gelatinous envelope, which is of great extent, is broken up
into clathrate segments. In Ccelosphcerium Nag., a common organism
in bog-pools moving about with considerable rapidity, it is lobed at the
margin, the pseudocysts appearing like blue-green projections >on the
surface of the globe. Chroodactylon Hansg. (Ber. Deutsch. Bot.
Gesell., 1885, p. 14) is distinguished by the formation of cell-families
branching in an arborescent manner, by its distinct cell-nucleus, and

448 PROTOPHYTA

.

by the star-shaped chromatophores which enclose moderately large
pyrenoi^s. It has possibly been erroneously referred to this family.

Most of the genera and species of Chroococcaceas grow in moist
situations, as on damp rocks, where they frequently form large shining
blue-green mucilaginous masses ; others swim freely on the surface of
bog-pools ; a few are found in salt water, attached to sea-weeds. The
gonids or algal constituents of many lichens have been shown to be pro-
tophytal organisms belonging to the Chroococcaceae. As it is highly
probable that many forms at present included in the family are stages in
the history of development of more highly organised protophytes, or even
of algae, their place in a final system of classification is altogether un-
certain until their life-history has been more thoroughly investigated.
Many are closely analogous to corresponding forms among the Protococ-
caceae, as Chroococcus to Chlorococcum, Glceocapsa to Gloeocystis,

«N

FlG. yn.—Microcystis marginata Men. FIG. •$•]%.— Caiosphcerhim Kiitzingianum Nag.
(x 400). (After Cooke.) (x 400). (After Cooke.)

Aphanocapsa to Protococcus, Coelosphaerium to Botryococcus, and
Merismopedia to Tetraspora; but they are probably merely parallel
serie^ of forms without any direct genetic connection. Richter, however,
identifies Glceocapsa and Gloeocystis.

The same observer suggests also a genetic affinity lietween the
various genera usually included under the Chroococcaceae of the follow-
ing nature. The lowest form is the naked Aphanocapsa-condition,
corresponding to Palmella among the Protococcaceae. From this naked
or only slightly encysted condition is developed the Gloeocapsa- or
Gloeocystis-form, with several gelatinous envelopes, the Chroococcus-
condition, where the investment is altogether wanting, and the coenobe-
or Ccelosphaerium-condition, where there is only a slight vesicular
envelope. The Gloeocapsa -form is especially adapted for exposure to
air and growth upon a comparatively dry substratum ; the coenobe-type
is developed in wa^er or on a moist substratum in the air. With this
is connected the cylindrical form, a higher stage, because it displays
differentiation in the direction of growth, and a development towards

CYANOPHYCE& 449

the filiform condition. This cylindrical condition, when attained, is
usually unstable, but becomes stable in Synechococcus. Glceocapsa may
also pass into an encysted filiform condition in Sirosiphon (see p. 439).
Zopf insists on the close affinity between the blue-green Schizo-
phycese and the Schizomycetes. Hansgirg regards many of the forms
included under Chroococcus as resulting from the breaking up of fila-
ments of the higher Cyanophyceae such as Lyngbya, while Glceocapsa
may be derived in the same way from Stigonema, and Synechococcus from*
Calothrix. He believes, in fact, most if not all of the organisms hitherto
included in this family to be connected, by retrogressive metamorphosis,
with other more highly developed forms, and even possibly in some
cases (Flora, 1886, p. 291) with the protoneme of a moss. Microcystis
is regarded by Richter (Hedwigia, 1885, p. 18) as a resting-form of
Euglena. The Chroococcaceae, like the other Cyanophyceae and the
Protococcaceae, enter largely into the composition of Lichens. The
reader will find this subject amply treated by Bornet in his ' Recherches
sur les gonidies des Lichens ' (Ann. Sci. Nat., 5 Ser., xvii. and xix.).

LITERATURE.

Nageli- Gattungen einzelliger Algen, 1849.

Borzl— Nuov. Giorn. Bot. Ital., 1878, p. 369 ; and 1879, p. 47.

Richter— Hedwigia, 1880, pp. 154, 169, 191.

Zopf— Bot. CentralbL, x., 1882, p. 32; and Ber. Deutsch. Bot. Gesell., 1883,

P- 319'

Tangl — Anzeiger Akad. Wiss. Wien, 1883, p. 87.
Hansgirg— Oesterr. Bot. Zeitschr., 1884, pp. 313, 351, 389; and Bot. Centralbl.

xxii. and xxiii., 1885.

GROUP II. AND CLASS XXVIIL— SCHIZOMYCfTES
(BACTERIA).

Though this group has been the subject of a great deal of investiga-
tion and much speculation, it cannot be said that our knowledge of it
is in due proportion to the literature. The minute size of the cells pre-
cludes an exact study of their structure. This leads to errors of deter-
mination and to confusion of forms in culture experiments, and thus
renders difficult the study of the course of development. A large number
of the investigators have been and are unequipped with a knowledge
of natural history, and are unfitted to appreciate the significance of
phenomena observed, or, in other cases, are incapable of observation of

G G

45o PROTOPHYTA

the kind at all. Records of the successive occurrence of different
forms in the same situation have been substituted for direct observations
of continuity, while errors of even grosser kind abound in the vast
literature of the subject. Bacteria are the present refuge of those
who believe in ' spontaneous generation,' just as higher forms of organ-
ised beings were the subject of their speculations in former times, when
the instruments of investigation were less perfect.

Bacteria are either single minute cells of roundish form, or cylin-
drical and rod-like cells or rows of cells. As has been said, their very
minute sizetias prevented our attaining an exact knowledge of the cell-
structure. The cell-cavity*is ordinarily filled with homogeneous proto-
plasmic contents. Chlorophyll has been discovered tingeing the proto-
plasm in three forms — Bacterium viride and Bacillus virens of Van
Tieghem, and more faintly in Bacterium chlorinum of W. Engelmann.
A red colouring matter discovered by Lankester, and named by him
bacteriopurpurin, tinges the protoplasm of Beggiatoa roseo-persicina
(Zopf ), but though colours are often associated with masses of Bacteria,
it is difficult to discern in the magnified view the exact seat of it,
whether it occur in cell-contents, cell-wall, or substratum. In some
forms (which do not contain chlorophyll) a substance resembling starch
is round. No one has yet detected nuclei with absolute certainty. The
cell-membranes are very delicate, and in such cases as Spirillum
(Ehrenb.) highly elastic, but it happens to most Bacteria at one stage of
their development that gelatinous outer layers are formed, which either
inve|t single cells and cell-groups, or unite into masses large numbers
of cells. A great number of Bacteria have the power of free movement.
During such movement rotation takes place round the longitudinal
axis, while movements of oscillation also occur in other forms, Cilia or
flagella are found in some, but not all, of these moving Bacteria, and it
has not been proved that they are motile organs as one might too readily
infer. As a matter of fact it is not known, in many cases, whether
these flagella are parts of the membrane or of the protoplasm protruded
through it ; and since they are not always present in motile Bacteria,
they need not be regarded as essential organs of locomotion at all
events.

Various growth-forms occur which were at first associated with dif-
ferent Bacteria and received generic names. Individual Bacteria are
either roundish or in the form of straight rods, or of twisted rods. As
de Bary has remarked, ' a billiard ball, a lead pencil, and a corkscrew so
exactly illustrate these three chief forms,' that there is no need of models
to convey instruction in this respect. The round growth-forms are
termed Coccus \Micrococcus Cohn &c.) ; the rod-like forms include those

SCHIZOMYCETES

which have been termed Bacillus Cohn (long rods), and specially Bac-
terium Cohn (short rods) ; the shortly coiled forms acre kribwn as Vibrio
Cohn ; and the spiral forms have received the names of Spirillum
Ehrenb., Spirochceta Ehrenb., &c., and the very elongated filiform
forms are Leptothrix Ktz., Beggiatoa Trev. &c. Involution forms are
swollen bladder-like structures of irregular outline probably produced by
malnutrition. These growth-forms of cells or of individuals either occur
free, or in the form of filaments, or more seldom of flat surfaces or
cube-like packets. Large gelatinous masses called Zoogl&a, composed of
numerous individuals of these growth-forms, occur in various situations
such as the surfaces of fluids and solids, or they may be found
suspended in fluids.

O O O a

cos

FIG. 379. — Bacillus Fitzianus Zopf. Transition forms from round cocci to rods.
d, with spores ( x 4,000). (After Buchner.)

Such forms of Bacteria are grouped into two divisions, viz. those
which form their spores endogenously, the Endosporous Bacteria, and
those which have no su&i mode of forming spores, the Arthrosporous
Bacteria. This classification, which can hardly be regarded as finally
satisfactory, corresponds, at all events, with the state of our knowledge
of the course of development of Bacteria.

Endosporous multiplication is accomplished by the formation within
a cell of a minute, granule-like body, which gradually enlarges, whije
the surrounding protoplasm disappears until it reaches its mature form

G G 2

452

PROTOPHYTA

within the wall of the mother-cell. The mature spore is usually a highly
refringent body with definite outline, and of globular or ellipsoidal form.
The formation of spores commonly takes place when the substratum
yields no more nourishment, or vegetation is otherwise interrupted, and
it usually occurs in most of the cells, others remaining sterile. Arthro-
sporous reproduction is effected by the simple separation of members
which form the starting point of new growths.

The spores of Bacteria are capable of germination from maturity
onwards, often for considerable periods. They withstand the operation

of external agencies, such as ex-
treme degrees of temperature and
the like, with varying success, many
of^them exhibiting astonishing en-
durance. Such arthrosporous forms
as Beggiatoa, which vegetate in

/water, are probably incapable of
withstanding desiccation at a very
high temperature, but the spores
of endosporous Bacteria possess,
many of them, remarkable powers
of endurance. The spores of Ba-
cillus Anthracis (Cohn) (the cause
of splenic fever) remain alive in
absolute alcohol. They may be
kept for at least three years in an
air- dry state, and for at least one
year in water, and probably for
longer either in air or in water.
They were found by Brefeld to with-
stand boiling in a nutrient solution for
a quarter of an hour, the greater part
of them for half an hour, a smaller
number for one hour, but none
for three hours. And so with the
spores of other forms. The tempe-
ratures at*which germination takes

place, the minimum, the optimum, and the maximum, vary with different
forms ; but for the most part the minimum and certainly the optimum
may be said to be above the ordinary temperature of a room. Similarly
the optimum temperature for vegetation is usually high, being about
3o°C., speaking very generally.

With reference to their behaviour towards fhe supply or exclusion of

FIG. 380. — Bacillus Megaterimn de By. a,
outline of a motile chain of rods ; b, a pair of
same ; /, a quadricellular rod after treatment
with alcoholic solution of iodine ; c, a five-
celled rod before spore-formation ; d— f, suc-
cessive stages of pair of rods while forming
spores, about an hour interval between each —
state d was about two o'clock afternoon, and
the spores in f were ripe towards evening ; r,
a quadricellular rod with ripe spores ',' g1 a
five-celled rod with three ripe spores placed
in a nutrient solution after several days' desic-
cation at 12.30 ; g", same about 1.30 ; g*t the
same about 4 o'clock ; A1, two spores with
the walls of the mother-cells dried, and then
placed in a nutrient solution about 11.45 \ h~,
the same about 12.30; z, k, /, later stages of
germination ; m, a rod formed from a spore
placed eight hours before in a nutrient fluid,
and in the act of splitting transversely, (a x
250, the other figures x 600.) (After de Bary.)

SCHIZOMYCETES

453

FIG. 381. — Bcggiatoa alba Trev. i, group ol filaments. 2 — 5, filaments of varying thickness, 5
breaking up ; small dark circles in all cases grains of sulphur ; where such are abundant transverse
segmentation is indistinct. 6—8, filaments rich in sulphur showing transverse segmentation after
treatment with solution of methyl violet ; in 8 longitudinal division is shown (formation of cocci or
spores). 9, filaments which have broken up into spores. 10, mottle spores, (i x 540, other figures
x 900.) (After Zopf.)

454 PROTOPHYTA

oxygen, there ^s great variation among Bacteria. This variation extends
from those forms, called aerobiotic by Pasteur, which require a plentiful
supply of free oxygen for the purpose of vegetation (e.g. Bacillus sub-
tilis, Cohn), to others (anaerobiptic) in which vegetation is promoted by
its exclusion (e.g. Bacillus Amylobacter, Van Tiegh.). Intermediate
forms occur between such extremes ; and Nageli has shown that
aerobiotic forms continue to vegetate when the supply of free oxygen
ceases.

Speaking in general terms, what has been said already of the mode
of life of Fungi in other respects, e.g. nutritive adaptation, holds
good of such Bacteria as contain no chlorophyll. They are saprophytes
exciting fermentations and producing combustions of the substratum,
and putrefactive processes ; or parasites, though very rarely on living
plants, it may very well be on account of the acid reaction. As para-
sites in living animals they obtain the greatest share of our interest,
since, as everyone knows, it is sought to connect them with a large
number of diverse diseases. Thai this attempt is made with the
greatest rashness in many cases, on utterly insufficient data, often on
the mere presence of some vaguely determined form in diseased tissues,
is a scandal of medical literature. On the other hand it has been
thoroughly proved in certain cases that their presence and action have
the character of exciting causes of disease, and it cannot be doubted
that painstaking research will bring to light numerous other instances of
equal weight. Slipshod research will only retard progress in this direc-
tion. It has already done much in obscuring results, and in placing
obstacles in the path. The most noteworthy ijeature, as de Bary has
pointed out, in the parasitism of Bacteria in the living bodies of
animals is their facultative parasitism — (as illustrated for example in
the well-established case of Bacillus Anthracis in anthrax or splenic
fever), a matter of grave importance from the medical point of view.

Among saprophytes may be mentioned Bacterium Termo (Duj.),
an exceedingly abundant agent of putrefaction ; Bacillus Megaterium
(de By.) (fig. 380), and Beggiatoa alba (Trey.) (figs. 381, 382), the
' sewage-fungus ' of engineers, found in sulphuretted waters, the effluents
from manufactories and sewage-works, which has a remarkable power of
extracting sulphur fr^n the water, and storing it up in the form of minute
refringent globule^.

*As regards the position ofcBacteria, ' to say that they are offshoots of
the Fungi is to " contradict all trustworthy observations " so flatly, that
tri0 view need not be seriously discussed in this place' (de Bary, 'Comp.
Morph.,' &c., p. 474). ^They are only fungi in the very limited sense of
their b^ing 'thallophytes which contain no chlorophyll,' and indeed it

SCHIZOMYCETES

455

has been seen that certain Bacteria do contain chlorophyll. Looking
at their morphological characters, so far as these are at present known
to us, it cannot be doubted that the nearest allies of the Arthrosporous
Bacteria are those Protophyta, Nostocaceae, Oscillariaceae, Chroococcaceae,
&c., which contain chlorophyll. Leuconostoc (Van Tiegh.) has already
been mentioned (p. 433) as an intermediate form. A gap certainly
exists between Arthrosporous and Endosporous forms ; but so far as

FIG. 382.— Bcggiatoa alba Trev. Curved and spiral forms. A, attached filaments. B — H, por-
tions of spiral filaments ; H showing separate cells, E swarming (' spirillum ') with a cilium at each
end. Small dark circles are sulphur granules ( x 540). (After Zopf.)

can be seen the latter stand nearer to the former than to any other
group, and the interval which separates them may become narrower with
farther knowledge. On the other side a connection appears to be in-
dicated between Bacteria and the Flagellata ; but more than this one

456 PROTOPHYTA

can hardly say. In conclusion, and as summing the matter up, the
words of de Bary (' Comp. Morph.,' &c., p. 475) may be quoted. ' If we
assume for a moment a connection between the Bacteria and the
Flagellata, it is evident that as a consequence the following series of
forms converge to the Flagellata : firstly, the series of Bacteria and the
Nostocaceae ; secondly, that of the Mycetozoa ; thirdly, 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. . . . fourthly, and lastly, the Rhizopoda and the
Protozoa with the animal kingdom, which connects writh these in an
ascending line.'

LITERATURE.

De Bary— Vorlesungen tiber Bacterien (Leipzig, 1885 and 1886). (See English trans-
lation by Garnsey and Balfour, Oxford, 1887.)

The above contains an admirable guide to the literature of the subject. (See
also the same author's Comparative Morphology, &c.)

Cornil et Babes— Les Bacteries, &c., 2nd ed. (Paris, 1886). *

Crookshank— Introduction to Practical Bacteriology (London, 1886).

Duclaux — Chimie biologique (Paris, 1883).

Grove — A Synopsis of the Bacteria and Yeast Fungi (London, 1884).

Klein — Micro-organisms and Disease, 3rd ed. (London, 1886).

Hueppe — Die Formen der Bacterien (Wiesbaden, 1886).

Hueppe — Die Methoden der Bacterienforschung (Wiesbaden, 1885).

Zopf-Die Spaltpilze (Breslau, 1884).

The references to the vast literature of the subject in the above books will be a
sufficient guide to the most ardent student. At the same time it would be unpardon-
able to abstain from a special reference to the labour^ of Cohn, Pasteur, Koch, Lan-
kester, Brefeld, Van Tieghem, Prazmowski, Naegeli, and Lister, since these are of
fundamental importance.

INDEX.

figures in large type refer to Illustrations.}

AHIES, 3

Abjunction, 312, 275

Absidia (Van Tiegh.), 338, 339

Absorbing system, 138

Acanthococcus (Lagerh.), 417

Acetabularia (Lmx.), 286, 251, 252

— mediterranea (Lmx.), 251, 252
Achlya (Nees ab Esenb.), 335, 346, 291, 292

— polyandra (Hildebr.), 291

— racemosa (Hildebr.), 291
Achnanthes (Bory), 426

— brevipes (Ag.), dt>7
Acrasieae, 401, 405, 406
Acrasis (Van Tiegh.), 405
Acroblaste (Reinsch), 280
Acrocarpi, 149

Acrogynous Jungermanniaceae, 161
Acrospore, 330, 343, 352, 361, 362, 363, 364,

365, 367, 368> 369> 37°) 372, 373, 374, 376
Acrosticheae, 80, 83
Acrostichum (L.), 85
Adder's Tongue, 100
Adiantum (L.), 85, 44, 50, 58

— capillus-Veneris (L.), 44, 50
Adventitious bud, 77, 81, 100, 49
^Ecidia, 384, 385, 386, 314
^cidiospore, 6, 384, 385, 386, 314
j£cidium(Pers.). 3§3 .
yEgopodium Podagraria, 348, 349
Aerial leaf, 28, 7, 8
Aerobiotic Bacteria, 454
/Ethalium septicum (Fr.), 403
Agar-agar, 210

Agaricini, 393, 394, 270, 273, 318-321
Agaricus (L.), 4, 392, 393, 270, 273, 319, 320

., 4, 39

— campestris (L.), 3
ilus (Bull.)

— oryophilus (Bull.), 273

— Emerici (Berk.), 316

— Gardn- ri (Berk.), 316

— igneus (Tul.)» 3J6

— lampas (Berk.), 316

— melleus (L.), 309, 310, 3*6, 392, 270, 319

— noctilucens (LeV.), 316

— olearius (DC.), 316
Agarum (Grev.), 244
Aglaozonia (Zan.), 251

— reptans (Ktz.), 252

Air-bladder, 232, 236, 241, 244, 206, 207, 211

ANO

Air-cavity, 102, 105, 109, 147, 167, 169, 24, 110,

112, 153, 154

Akincte, 185, 258, 274, 446
Alaria (Grev.), 239, 244

— esculenta(L.), 244
Alcoholic ferment, 380
Algae, 2, 3, 4, 184,

Algal cells of Lichens, 318, 319, 370, 279-282,

307, 308

Alsophila aculeata (Klotzsch), 57
AIteinaria(Nees ab Esenb.), 374
Alternation of generations, 16, 182, 189, 214,

263, 325, 440
Amanita, 393
Amansia (Lmx.), 194, 209
Amoeba, 406
Amoeboid motion, 196, 199, 217, 274, 284, 344,

401, 402, 403, 405, 406
Amphigaster, 160, 138, 139
Amphipleura (Ktz.), 426
Amphiroa (Lmx.), 206
Amphithecium, 145
Amphithrix (Ktz.), 437
Amphora (Ehrb.), 426
Amylum-star, 176
Anabaena (Bory), 430, 432, 433, 360

— flos-aqu33 (Fr.), 360
Anacrogynous Jungermanniaceae, 161
Anadyomene (Lmx.), 289
Anaerpbiotic Bacteria, 454
Ancylisteae, 4, 330, 344, 345
Ancylistes (Pfitz.), 331

— Closterii (Pfitz.), 330
Andreaea (Ehrh.), 145, 150, 123, 124

— alpestris (Schmp.), 123, 124
Andreaeaceae, 136, 150, 123, 24
Androspore, 6, 225, 202
Aneimia (Sw.), 78, 90, 91, 43

— Phyllitidis (Sw.), 43
Aneura (Dum.), 164
Angiopteris (Hoffm.), 91, 94, 95, 71

— caudata (De Vriese), 71

— evecta(Hoffm.), 93
Angiosperms, 12, 13
Annularia(Brongn.), 126, 101

s, 74, 78, 86, 89, no
56, 83, 110, 112, 319,320
Anomceneis spherophora (Pfitz.), 354A

458

INDEX

ANT

Antherid, 7 (see also under Vase. Crypt., Muse.,
Char., Algae, and Fungi), 11, 30, 36, 43, 44, 65,
74, 78, 106, 108, 130, 141, 157, 163-165, 175-
177, 192, 199, 201-203, 208, 210, 248, 259, 286.
290, 291,303-306,314

Antheridial tube, 291

Antherozoid 7 (see also under Vase. Crypt.,
ungi), 11, 15, 17,
„,, , , , « i*n i"
210, 248, 259, 290

Muse., Char., Alga;, and Fungi), 1

20, 30, 44, 78, 108, 130, 157, 163, 199, 201,

Anthoceros (L.), 157, 165, 144, 145

— laevis (L.), 144, 145
Anthoceroteae, 159, 164, 144, 145
Antipodal cells, 15
Aphanizomenon (Morr.), 430, 432, 361

— flos-aquae (Morr.), 432, 361
Aphanocapsa(Nag), 412, 440, 445, 447 448
Aphanomyces (de By.), 334, 335
Aphanothece (Nag.), 447, 375

— microscopica (Nag.), 375
Aphlebia, 120, 92

Apical cavity, 179

— cell, 23, 41, 74, 90, 98, 102, 105, 156, 173, 174,
176, 191, 214, 228, 241, 437, 52, 162

— papilla, 179
Apiocystis(Nag.), 413, 341

— Brauniana (Nag.), 341
Aplanes Braunii (de By.), 334
Aplanospore, 185, 258, 274
Aplolepidae, 148
Apogamy, n, 52, 69, 86, 47
Apophyse, 148, 112, 124
Apospory, n, 69, 86, 48
Apothece, 355, 356, 370, 372, 373, 308
Appendage, 378, 379, 312
Appendiculce, 363

Aquilegia, 364
Archaeocalamites (Stur), 126, 99

— radiatus (Stur), 99

Archegone, 8 (see also under Vase. Crypt..

Muse., Char., and Alga), 4, 10, 14, 20, 29,

43, 45, 46,61, 74, 79, 80, 109, 131, 141, 142,

147, 148, 158, 164, 165, 166
Archegoniophore, 86, 61
Archespore, 13, 20, 36, 60, 80, 99, in, 134,

135, 144, 146, 159, 33, 56, 110 .
Archidium (Brid.), 145, 150
Areolation, 420
Arthrocladia (Duby), 245
Arthrodpnte33, 148
Arthropitys (Gopp.), 126
Arthrosporous Bacteria, 451, 452, 455
Artotrogus (Mont.), 325
Ascobolus (Pers.), 356, 359, 360, 361, 368, 369,

37°, 372> 378, 305

— furfuraceus (Pers.), 305

Ascogenous hyphae, 353, 355, 360, 364, 366, 367,
368, 369, 370, 372, 373, 374, 305, 306, 308

Ascogone, 360

Ascomycetes, 4, 312, 353, 383, 386, 267, 268,
271, 276, 278, 300-313

— course of development, 361

— homologies of the organs, 377
- (doubtful), 4, 378, 312, 313
Ascophylla (Stackh.), 235

Ascospore, 6 (see also under Ascomycetes), 268,

276, 278, 300, 304, 311, 312, 313
Ascotricha (Berk.), 370
Ascus, 353 (see also under Ascomycetes), 276,

300, 303, 305, 308, 311, 312
Aseroe (La Bill.), 398, 331

— rubra( Berk.), 331
Aspergillus glaucus (Lk.), 366
Asperococcus(Lmx.), 241, 245, 218

— bullosus (Lmx.), 218

BAT

Aspidieae, 83
Aspidium (Sw.), 85, 42, 55, 58

— filix-mas (Sw.), 72, 76, 77, 82, 42, 55
Asplenieae, 83

Asplenium (L.), 69, 85, 49, 51, 56, 58
-- Adiantum-nigrum (L. ', 51

— bulbiferum (Forst.), 81

— decussatum (Sw.), 49

— Trichomanes (L.), 56
Assimilating tissue, 138, 193
Asterophyllites (Rev.), 126, 130, 101
Asterotheca (Presl), 122, 94

— Sternbergii (Stur), 94
Astromyelon (Williams.), 126
Athyrium filix-foemina (Bernh.), 69, 76
Atrichum undulatum (P. B.), 102, 119
Attachment-disc, 228
Aulacodiscus (Ehrb.), 426
Aulacomnion (Schw.), 149

— androgynum (Schw.), 140
Aulosira(Kirchn.), 430, 433
Auricle, 92, 161, 140
Auxiliary cell, 203
Auxospore, 6, 422, 423, 355
Azolla (Lam.), 19, 26, 31, 115, 12, 13

— caroliniana (Willd.), 13

— filiculoides (Lam.), 12
Azygosperm, 338, 340, 342, 343
Azygites (Fr.), 338

BACILLARIACE^E, 419

Bacillus (Cohn), 44o, 451, 379, 380

— amylobacter (Van Tiegh.), 454

— anthracis (Cohn), 452, 454

— Fitzianus (Zopf), 379

— Megaterium (de By.), 454, 380

— subtilis (Cohn), 454

— virens (Van Tiegh.). 450
Bacteria, 305, 306, 449

— conditions of vegetation, 452

— growth-forms of, 450

— mode of life, 454

— movements of, 450

— spores of, 451, 452
Bacteriopurpurin, 450
Bacterium (Cohn), 451

— chlorinurn (Engelm.), 450

— Termo (Duj.), 454

— viride (Van Tiegh.), 450
Baeomyces (Pers.), 361
Balsamia (Vitt.), 358

Bangia (Lyngb.), 190, 191, 216, 193-195

— ceramicola (Chauv.), 193

-- fusco-purpurea (Lyngb.), 194, 195

Bangiaceae, 216

Barberry, 383, 384, 385

Barbula (Hedw.), 140, 147, 149, 105

Barilla, 190

Bartramia (Hedw.), 149

Basal cell, 68

Basid, 312, 384, 385, 388, 389, 390, 393, 394,

275, 317, 321
Basidiomycetes, 4, 306, 312, 388, 266, 270, 273,

316-331

Basidiomycetous Lichens, 319
Basidiospore, 6, 312, 388, 389, 390, 275, 317,

321, 322, 325, 329
Basilar cell, 433, 365
Batarrea(Pers.), 308, 397, 325, 326

— Steveni (Fr.), 325, 3iib
Batrachospermeae, 211, 189-191
Batrachospermum (Bory), 191, 211, 212, 213,

214, 189

— moniliforme (Roth), 189

INDEX

459

BEA

Beam, 226, 204
Beer-yeast, 268, 313
Eeggiatoa(Trev.), 4, 451, 452, 381, 382

— alba (Trev.), 454, 381, 382

— roseo-persicina (Zopf), 450
Biddulphia (Gray), 426
Binuclearia (Witt.), 276
Bladder-wrack, 230, 236
Blasia (Mich.), 156, 157, 164
Blechnum (L.), 85, 58
Blyttia(EndL), 160
Bog-mosses, 151

Boletus (L.), 392, 396
Bonnemaisonia (Ag.), 201
Bornetia(Thur.), 194, 209

— secundiflora (Ag.), 194
Bornia (Brongn.), 126
Borzia (Cohn), 428, 444

— trilocularis ((John), 445
Bothrodendron (L. and H.), 116
Botrychium (Sw.), 97, 98, 99, 100, 73-75

— Lunaria (Sw.), 97, 98, 100, 73-75
Botrydiaceae, 280, 285, 250
Botrydina (Breb.), 186, 412

Botrydium (Wallr.) 186, 284, 285, 410, 412, 250

— granulatum (Wallr.), 285, 250
Botryococcus (Ktz.), 186, 418, 448, 349

— Braumi(Ktz.), 349
Botryopteris (Ren.), 122
Botrytis cinerea (Pers.), 374
Brachytrichia (Zan.), 437
Bract, 173, 163-165
Bracteole, 173

Brake, 82

Breaking of the meres, 432
Brittle-worts, 181
Brownian movement, 269
Bruckmannia (Stbg.), 127
Bryaceae, 136, 146, 102-120
Bryum (L.), 145, 149, 115

— argenteum (L.), ii5
Bryopsideae, 289
Bryopsis (Lmx.), 289, 290

Bud, 133, 181, 196, 214, 250, 252, 162

Bulbil, 61, 67, 176

Bulbochaete (Ag.), 188, 222, 226, 202

- setigera (Ag.), 202

Bundle-sheath, 44, 109

Bursulla (.Sorok.), 405

Buxbaumia (Hall.), 149

CABBAGES, 326

Calamariese, 125. 130, 96-100

Calamites, 125, 126, 97

Calamitina (Weiss.), 126, 98

Calamocladus (Schmp.), 126

Calamodendreae. 125

Calamodendron (Brongn.), 125, 126

Calamostachys (Schmp.), 125, 127

Calcareous incrustation, 181, 195, 206, 211, 286,

3°4, 4°3> 44°> 167
Calcium oxalate, 85, 308
Callithamnion (Lyngb.), 4, 189, 191, 194,201,

204, 180

— caudatum (Ag.), 194

— seirospermum (Griff.), 204, 1 80

— versicolor (Drap.), 204
Callus, 240, 244, 217

Calothrix (Ag.), 435, 436, 445, 449, 364

— Crustacea (Thur.), 364
Calotrichaceae, 433
Calypogeia (Radd.), 162, 164, 134

— Trichomanis (Cord.), 134
Calypter. 134, 144, 110, 114, 117, 131,

Campylodiscus (Ehrb.), 426

Canal, 143, 109

Canal-cell, 69, 133, 45

Capillitium, 358, 396, 397, 404, 326, 334

Capitulum, 177, 163

Capsella bursa-pastoris, 326

Capsosira (Ktz.), 439

Carinal canal, 106, 108

Carpogenous cells, 176, 179

Carpogone, 8, 185, 199, 359, 360, 361, 362, 363,

364, 365, 366, 367,368, 369, 370, 37i, 372, 373,

385, 179, 303-50 '(
Carpomitra (Ktz.), 241
Carposperm, 185, 201, 203
Carpospore, 185, 201, 222, 263, 179, 199
' Carposporeae, 3
Carpostome, 201
' Carrageen moss,' 210
Casuarina, 113

Latharinea undulata (W. & M.), 102
Caudex, 71
Caulerpa (Lmx.), 289, 256

— prolifera(Lmx.), 266
Caulerpeae, 289, 256
Cell-cap, 222, 200
Cellulin, 176
Central bundle, 138

— cavity, 105, 81

— cell, 10, 14, 17, 26, 31, 69, 133, 143, 159, 109,
158

— node, 353

Ceramiaceee, 196, 204, 172, 179-181
Ceramidium, 201
Ceramium (Lyngb.), 204, 181

— stricturn (Grev.), 181
Ceratieae, 404
Ceratium (Lk.), 404, 335

— hydnoides (Alb. & Sch.), 335

— porioides (Alb. & Sch.), 335
Ceratodon (Brid.), 149

Ceratopteris thalictroides (Brongn.), 77, 81, 52

Ceterach (Adans.), 85

Cetraria islandica (Ach.), 283

Chaetangiaceae, 211

Chaetociadieae, 339

Chaetocladium (Fres.), 339, 340, 350

Chaetomium (Kze.), 370

— fimeti (Fckl.), 356
Chaetomorpha (Ktz.), 276
Chaetopeltis (Bert.), 222
Chaetophora (Schr.), 273, 275, 276
Chaetophoraceae, 222, 258, 273, 275, 279
Chaetopteris (Ktz.), 249

' — plumosa (Ktz.), 249
Chaetostylum (Van Tiegh.), 339
Chalara Mycoderma (Cienk.), 380
Chamaesiphon (A. Br.), 444
Chamaesiphonaceae, 441, 444
Chantransia(Fr.), 211, 213, 214, 216, 190, 191

— corymbifera (Thur.), 214, 191

— virgatula (Thur.), 190

Chara(L.), 174, 175, 176, 179, 181, 182, 160-
162, 164, 167, 168

— aspera (Willd.), 176

— crinita (Wallr.), 181

— fragilis (Desv.), 176, 160, 162, 164, 168

— hispida(L.), 176, 161,167
Characese, 15, 173, 160-168
Characiacea?, 410
Characin, 181, 416
Characium(A. Br.), 345, 412, 340

- ornithocephalum (A. Br.), 340
Charese, 173, 182, 160-162, 164, 167, 168
Cheilanthes (Sw.), 85, 58
Chiloscyphos (Cord.), 164

460

INDEX

CHL

Chlamydococcus (\. Br.), 186, 299, 300, 409,

— nivalis (A. Br.), 416
Chlamydomonas (Ehrb.), 186, 299, 300, 409,

417, 419

— Morieri (Dang.), 300

— pulvisculus (Miill.), 300
Chlamydospore, 6, 339
Crilorochytrium (Cohn), 284, 345, 410
Chlorococcum (Fr.), 417, 448, 347

— gigas (Grun.), 417, 347
Chlorogonium (Ehrb.), 300
Chlorophyceae, 305
Chlorophyllophyceae, 409
Chlororufin, 279
Chlorothecium (Brzi.), 411
Chlorotylium (Ktz.), 280
Choanephora(Cunn.), 340
Choiromycss (Vitt.), 358
Chondria (Ag.), 209
Chondrioderma diffbrme (Rost.), 332
Chondrites (Sternb.), 304
Chondrus (Grev.), 208, 185

— crispus (Stackh.), 210, 185
Chorda (Stackh.), 241, 216

— filum (Stackh.), 242, 216

— tomentosa (Lyngb.), 244
Chordaria (Ag.), 247, 220

— flagelliformis (Ag.). 220
Chordariaceae, 190, 247
Chromatophore, 194, 410, 427, 444, 445
Chromophyton (Wor.), 188, 257
Chroococcaceae, 409, 419, 427, 446, 455, 374-378
Chroococcus (Nag.), 417, 44i, 445, 446, 447,

448, 449, 374

— turgidus (Nae.), 374
Chroodactylon (Hansg.), 446, 447
Chroolepideae, 187, 258, 273, 279, 247
Chroolepus (Ag.), 280, 284

— aureum (Ktz.), 280

— lolithus (Ag.), 280

— umbrinum (Ktz.), 280
Chroomonas Nords-edtii (Hansg.), 445
Chrysochytriurn (Schroet.), 347
Chrysomyxa (Ung.), 386
Chylocladia (Grev.), 208

-Chytridiaceae, 4, 250, 344, 352, 297

— (doubtful), 347
Chytridium (A. Br.), 4, 249, 346
Cilia (of peristome), 135, 147, 111
Cinclidium stygicum (Sw.), 120
Cingularia (Wei-s), 128, 100

— typica (Weiss), 100
Circinate vernation, 72, 51
Circinella (Van Tiegh.), 339
Cladochytrieae, 344, 345) 346
Oadochytrium (Nowak.), 346, 352
Cladonia (Hill), 361, 279

— furcata (Hoffm.', 279
Cladophora (Ktz.), 275, 276, 330, 243

— gracilis (Ktz.), 243
Cladosporium herbarum (Lk.), 374
Cladostephus (Ag.), 249, 250
Clamp-connection, 306, 266
Clastidium (Kirchn.), 444
Clathrocysds (Henf.), 447
Clathrus (Mich.), 398, 399
Clavarieae, 391

Clavicep^ (Tul.), 361, 375, 309-311

— purpurea (Tul.), 375, 309-311
Cleistocarp, 355, 356

Closterium (Nitzsch), 259, 268, 269, 330, 239,

— Vianae (Ehrb.), 239

— rostratum (Ehrb.), 241

Clover, 364

Club-moss, 61

Coccidium, 201

Coccocarpia molybdia (Pers.), 280

Coccogone, 444

Cocconema lanceolatum (Ehrb.), 357

Coccus, 450, 379, 381

Codiolum (A. Br.), 413, 342

— gregarium (A. Br.), 342
Codium (Stackh.), 289, 290
Ccelastrum (Nag.), 186, 303, 265

— cubicum (Nag.), 265 •
Coeloblastae, 186, 281

Coelosphaerium (Naar.), 447, 448, 378

— Kiitzingianum (Nag.), 378
Coemansia (Van Tie^h. and Le Mon.), 341
Ccenobe, 184, 186, 291, 29?, 259-265
Coenobieae, 186, 291, 412, 418, 419, 259-265
Coleochaetaceae, 188, 190, 219, 220, 199
Coleochaete (Breb.), 189, 220, 199

— divergens (Prings.), 220

— pulvinata (A. Br.), 220, 199

— scutata (Breb.), 220

— soluta (Prings.), 220
Coleodesmium (Brzi.), 440
Collateral vascular bundles, 75, 89, 98
Collema (Ach.), 321, 322, 372, 385 307

— pulposum (Bernh.), 307

Collemaceae, 322, 359, 360, 361, 370, 372, 307

308

Collenchymatous tissue, 93
Colpodel'la (Cienk.), 405
Columel, 29, 86, 135, 145, 165, 339, 351, 110,

112

Commissure, 92

Completoria complens (Lohde), 343
Compositae, 364

Concentric vascular bundles, 18, 75, 98, 109
Conceptacle, n, 196, 199, 207, 232, 290, 182-184,

188, 208, 209

Conducting tissue, 138, 193
Conferva (L.), 185, 273, 274, 276

— bombycina (Ktz.), 273

Confervaceae, 185, 187, 190, 259, 273, 277, 278,

242-244

Confervites (Sch.), 304
Confervoideae, 237

— Heterogamae, 185, 188, 219, 199-204

— Isogamae, 185, 186, 272, 242^247
'Conid,' 327, 436, 444
Conidiobolus utriculosus (Bref.), 343
Conidiospore, 325, 327, 309
Coniferas, 13, 310, 3
Conjugatae, 185, 187, 258, 233-241
Conjugation, 185 (see also under Alga;,

Fungi, and Schizophyceae), 198, 222, 233-
238, 241, 246, 247, 252, 293-297, 299

Conjugation-tube, 346, 297

* Connubium,' 263

Consprtism, 318

Continuity of protoplasm, 66, 76, 192, 194, 230,
240, 428, 440

Contractile protoplasm, 422

— (pulsating) vacuole, 257, 292, 300, 409, 415
Convolvulus, 364

Coprinus stercorarius (Fr.), 392, 318, 321
• Copromyxa protea (Zopf), 406
' Copulation," 263
Cora(Fr.), 319
Corallina (L.), 189, 194, 206, 183, 184

— officinalis (L.), 206, 183

— rubens(L.), 184

Corallinacese, 196, 199, 203, 206, 182-184
Coralline, 195, 206
Cordyceps (Fr.), 376

INDEX

461

COR

Coremium (Lk.), 312
— • glaucum (Lk.), 367
Cork, 98

Cormophytes, 135, 156, 173
Corn-mildew, 383
Corpusculum, 14, 3
Corsinia (Radd.), 160, 166
Cortex, 173, 174, 221, 247, 39
Cortical lacuna, 81

— tissue, 76, 228, 242. 249, 321, 216, 271, 311
Corticium (Pens.), 391

Coscinodiscus (Ehrb.), 420, 426
Cosmarium (Cord.). 268, 269, 270, 239

— coelatum (Ralfs), 239

Cotyledon, 17, 28, 41, 55, 71, 105, 8, 9, 14
Craterospermum (A. Br.), 263
Cribrarieae, 401
Cronartium (Pers.), 386
Crouania (Ag.), 204, 172

— attenuata (Ag.), 172
Crown, 179, 164, 166
Cruciate (tetraspores), 195
Crucibulum (Tul.), 397, 327, 328

— vulgare (Tul.), 327, 328
Cruciferae, 326, 327
Cruoria (Fr.), 191, 193, 210
Crustaceous Lichens, 321
Cryptogramme crispa (R. Br.), 72
Cryptonemia (Ag.), 2c8
Cryptonemiaceas, 208
Crystalloid, 276, 288, 308
Ctenomyces (Eidam), 367
Cupule, 140, 157, 170, 155
Cupuliferss, 310

Cushion, 93, 115, 87

Cutleria (Grev.), 239, 241, 251, 26, 227

— adspersa (de Not.), 252

— multifida (Grev.), 252, 226, 227
Cutleriaceae, 187, 239, 251, 254, 226-229
Cyanocystis (Brzi.), 444
Cyanophyceae, 408, 409, 426, 358-378
Cyanophycin, 428

Cyathea (Sm.), 85, 124, 59

Cyatheaceae, 71, 73, 78, So, 81, 85, 123, 124, 57,

Cycadeae, 13, 1
Cyclomyces (Kze.), 392
Cyclopteris hibernica (Forbes), 121
Cyclosis, 175, 422, 163
Cylindrocapsa (Reinsch), 227, 414
Cylindrocapsacese, 228
Cylindrospermum (Ralfs), 430, 433, 362

— macrospermum (Ktz.), 362
Cymbella (As;.), 426
Cymopolia (Lmx.), 288

Cyst, 185, 258, 264, 272, 274, 278, 427, 429, 446

Cystid, 394, 321

Cystocarp, 201, 213, 169-171, 173, 174,176-178,

183, 184, 188, 189, 191
Cystopteris (Bernh.), 69, 85, 58

— bulbifera (Bernh.), 81

— fragilis (Bernh.), 67

Cystopus (Lev.), 312, 323, 326, 327, 328, 335,
269, 275, 285, 28 1

— candidus (Lev.), 326, 269, 285

— cubicus (LeV.), 326

— Portulacse (Lev.), 275, 287
Cystosira (Ag.), 235

DACRYOMYCES (Nees ab Esenb.) 389
Danaea (Sw.), 94, 95
Danaeites (Gopp.), 122
Dasya (Ag.), 196, 209, 174
— elegans(Ag.), 174

ECT

Dasycladaceae, 280, 281, 286, 251-255
Dasycladus (Ag.), 287, 288, 253

— clavaeformis (Ag.), 253
Davallia (Sm.), 85
Davallieae, 83
Delesseria (Grev.), 193, 208
Delesseriaceae, 208
Delphinium, 364
Derbesia (Sol.), 289
Dermocapsa (Crouan), 444

— violacea (Croua n), 444
Desiccation of spores, 315, 452
Desmarestia (Lmx.), 241

Desmidiaceae, 187, 190, 258, 259, 268, 239-241
Desmidium (Ag.), 187, 268, 239, 241

— Swartzii (Ralfs), 239, 241
Desmids, movements of, 269
Diaphragm, 31, 39, 105, 124, 125, 179, 9, 14
Diatoma (DC.), 424, 357

— elongatum (Ag.), 357
Diatomaceae, 187, 258, 408, 419, 353-357
Diatomin, 257, 421

Diatoms, movements of, 422
Diatrype (Fr.), 373
Dichothrix (Zanard.), 437
Dicksonia (L'Herit.), 71, 84, 85, 42

— antarctica (Lab.), 42
Dicranum (Hedw.), 138, 149
Dictyonema (Mont.), 319
Dictyopteris(Lmx.i, 254
Dictyosiphon (Grev.), 239, 241, 245

— hippuroides (Lyngb.), 247
Dictyosphasrium (Nag.), 412, 338

— reniforme (Buln.), 338
Dictyostelium (Bref.), 405
Dictyota (Lmx.), 254
Dictyotaceas, 188, 237, 254, 230, 231
Dictyuchus (Leitg.), 334, 335
Didymium (Schrad.), 316, 333

- serpula (Fr.), 333

Dimargaris (Van Tiegh.), 341

Diplolepidae, 148

Diploxylous bundles, 117

Dipsacus, 364

Disc, 170, 184, 220

Discocarp, 355, 369

Discomycetes, 308, 319, 355, 356, 370

Dispira (Van Tiegh.), 341

Diverticula, 209, 187

Docidium (Breb.), 268, 269. 239

— baculum(Breb.), 239
Doodia(R. Br.), 85
Dothidea (Fr.), 354
Draparnaldia,(Ag.), 273, 275, 276, 417, 244

— glomerata (Ag.), 244
Drilosiphon (Ktz.), 433, 438, 440

— Julianus (Ktz.), 440
Dry-rot, 309
Dudresnaya(Born.), 189, 202, 204, 179

— coccinea (Crouan), IV 9
Dulse, 210

Dumontia(Lmx.), 208
Dumontiera (Nees ab Esenb.), 171
Duriapa (Bor.), 166

Durvillaea (Bory), J^S, 228, 230, 235, 236
Dutch rushes, 113
Dwarf male, 225, 201, 202

ECKLONIA (Horn.), 244

Ectocarpaceae, 187, 239, 247, 212, 221, 222

Ectocarpus (Lyngb.), 187, 239, 241, 247, 221,

— investiens (Hauck), 221

— pusillus (Griff.), 249

462

INDEX

ECT

Ectocarpus siliculosus (Ktz.), 249, 222

Edible earths, 424

E'aehista (Duby), 247

Elaphomyceae, 358

Elaphomyces (Nees ab Esenb.), 357> 358, 359»

367
Elater, 102. in, 128, 134, 159, 163, 171, 84, 86,

158, 159

Elk's-horn-fern, 72
Embryo, n, 13, 17, 27, 40, 56, 105, 134, 180,

271, 21, 45, 158
Embryo-sac, 14, 3
Embryonic vesicle, n, 14, 3
Emeri'cella (Berk.), 319
Empusa (Cohn), 342, 343

— Grylli (Fres.), 343

— Muscae (Cohn), 343
Encalypta (Schreb.), 149
Encalypteae, 148
Encysted condition, 415
Endoclonium (Franke), 284
Endoderm, 76, 109
Endogenous spore, 424, 451, 379-381
Endophyllum (Lev.), 386
Endophytic Algse, 222

— Fungi, 317
Endosperm, 15, 39, 20
Endosphaera(Klebs), 284, 410

Endospore, 20. 47, 74, 80, 112, 134, 145, 160, 17
Endosporous Bacteria, 451, 452, 455
Endostome, 147
Endothecium, 145

Enteromorpha (Lk.), 217, 218, 219, 197
- intestinalis(Lk.), 197
Enterosora (Baker), 79
Entomophthora(Fres.), 342, 343
- curvispora (Nowak.), 342

— ovispora (Nowak.), 342

— radicans (Bref.), 342
Entomophthoreae, 4, 342
Entyloma(de By.), 350,. 351, 352
Envelope of plasmode, 403
Envelope-tissue, 355, 360, 361, 363, 364, 366,

368, 370, 373, 374;378,
Ephebe pubescens (Fr.), 281
Ephedra, 113
Ephemerum (Hampe), 150, 121

— serratum (Hampe), 121
Epichloe (Fr.), 361, 376
Epiderm, 39, 54, 153-155
Epidermal tissue, 10, 138, 193, 242, 216
Epiphragm, 146, 397, 112, ll7, 327
Epiphytic Algae, 237, 239, 248, 257. 444, 184, 221

— Fungi, 317
Epiplasm, 354

Epispore, 20, 22, 25, 36, 47, 14, 16

Epithemia (Br£b.), 426

Equiseta cryptopora, 107

- — phaneropora, 107

Equisetaceae, 19, 20, 100, 124, 2, 77-86, 96-101

Equisetites(Sch.), 124

— arenaceus (Brongn.), 124
Equisetum (L.), 102, 124, 2, 77-86

— arvense (L.), 106. 107, 109, no, 78, 79

— giganteum (L.), 113

— hyemale (L.), no, 113, 82

— limosum (L.), 109, in, 86

— littorale (Kuhl.), 109

— maximum (Lam.), no, 78, 81, 83

— palustre fL.), no

— pratense (Ehrh.), no
T- sylvaticum (L.), 77, 80
Eremascus (Eid.), 378, 302

— albus (Eid.), 359, 361, 302
.Eremobiss, 186, 410, 336-344

FON

Eremosphaera (de By.), 417
Ergot, 376, 309-311
Erysiphe (Hedw.), 317, 362, 363, 367, 378

— communis (Lk.), 364

— graminis (LeV.), 364

— lamprpcarpa (Lk.), 364

— Martii (Lev.), 364

— (Uncinula) spiralis (Berk. & Curt.), 36

Essential air-cavity, 106
Euastrum (Ehrb.), 268, 239, 241

— pectinatum (Breb.), 241

— rostratum (Ralfs), 239
Eucheuma spinosum (Ag.), 210
Eudorina (Ehrb.), 295
Euglena, 345, 410, 449, 297
Eunotia (Ehrb.), 424, 357

— monodon (Ehrb.), 357

Eurotium (Lk.), 359, 360, 364, 367, 378, 275, 304

— herbariorum (Lk.), 366, 275, 304

— repens (de By.), 304
Eutypa (Tul.), 373
Eusynchytrium (Schroet.), 347
Exciple, 355, 372, 308
Exidia (Fr.), 389, 317

— spiculosa (Sommerf.), 317
Exoascus (Fckl.), 379

— alnitorquus (.Sad.), 380

— aureus (Sad.), 380

— deformans (Fckl.), 379

— Pruni (Fckl.), 379
Exobasidium (Woron.), 389, 390

— Vaccinii (Woron.), 388

Exospore, 20, 47, 74, 80, 112, 134, 145, 160, 17,

20, 42
Extine, 166, 325, 337. 340, 347, 349, 351

FACULTATIVE parasites, 317, 454

— saprophytes, 317
False stomate, 107
Favella, 204, 181

Fegatella (Radd.), 168, 170, 171, 152

— conica (Cord.), 152
Female conceptacle, 232, 209

— filament, 266

— inflorescence, 151, 156

— prothallium, 15, 102, 103, 4, 79, 80
Ferment, 316, 380, 454

Ferns, 64, 119, 42-76, 92-95
Fertilising-tube, 202, 211, 179
Filament, 184, 428
Filamentous Lichens, 284
16, 17, 19, 2

Fiiices. 15,
92-95

64, 119, 42-71,

Filmy ferns, 71, 72, 88, 62-64

Fimbriaria (Nees ab Esenb.), 171

Fischera (Schw.), 439, 441

Fissidens (Hedw.), 137, 149

Fission, 185, 270, 240

Flagellate Infusoria, 410, 416, 455, 456

Float-corpuscle, 31

Floating apparatus, 31

Florideae, 185, 188, 191, 444, 169-198

Florideae-green, 194

' Flos-aquae,' 436

Flower, 134, 139, 141, 154, 104. 106, 129

' Flowering fern,' 73, 90, 66, 67

' Flowers of tan,' 403

Foliaceous Lichens, 321

Foliose Hepaticae, 135, 156, 160, 132-134, 137-

142

Fontinalis (L.), 145, 149, 111
— antipyretica (L.), Ill

INDEX

463

Foot, 17, 41, 71, 105, 144, 146, 154, 422, 14, 131
Fossil Cryptogams, 114, 172, 183, 303, 330, 424,

87-101
Fossombronia (Radd.), 156, 164, 135

— pusilla (Nees ab Esenb.), 135
Fovea, 50

Foveola, 51

Fragillaria (Lyngb.), 426

Fragmentation of nucleus, 176

Frond, 72, 191, 228, 239, 241, 242, 430, 432, 359

Frondose Hepaticse, 135, 156, 135, 136, 143-159

Front view (diatoms), 420. 353, 354

Fructification, 102, no, 5, 6, 77, 94, 96, 100, 101

Fruit, 180

Frullania (Radd.), 164, 139, 140

— dilatata (Nees ab Esenb.), 139

— Tamarisci (Bum.), 139
Frustule, 268, 419, 423, 353-355
Frustulia saxonica (Ag.), 355
Fruticose Lichens, 321, 283

Fucacese, 185, 188, 190, 228, 304, 444, 205-211

Fucoideae, 235, 237

Fucoxanthin, 230

Fucus (L.), 188, 235, 304, 207-210

' — amylaceus,' 210

— furcatus (Ag.), 228

— serratus (L.), 235, 207

— vesiculosus (L.), 232, 235, 236, 207-210
Fuligo varians (Somm.), 403

Funaria (L.), 149, 103, 106, 108-110
--- hygrometrica (L.), 103, 106, 108-110
Fundamental tissue, 10, 76, 39, 53, 54
Fungi, 3, 4, 305, 266-331

— cell-contents, 307

— cell-membrane, 308

— differentiation of thallus, 309

— histplogical characteristics, 306

— luminosity, 316

— nutrition, 316

— spores, 312

— conditions of germination, 314

— conditions of vegetation, 316
Fungus-cellulose, 308
Funictilus, 328

Funnel, 31, 36, 15

Furrow, 100, 106, 124, 129, 420, 353

GALAXAURA (Lmx.), 211

Galls, 284, 347

Gametange, 272, 277, 279, 296, 349, 411, 246,

247, 260, 298
Gamete, 259 335, 337, 338, 340, 346, 349, 350,

351, 293, 298, 299

Gasteromycetes, 309, 388, 395, 324-331
Gasteromycetous Lichen, 319
Gautieria (Vitt.), 395
Geaster (Mich.), 396
Gelatine, 190, 210
Gelatinous Lichens, 321

Gelidiaceas, 209
Gelidium (Lmx.), 209, 210

Geminella (Schroet.), 350

Gemma, 61, 86, 133, 140, 157, 170, 185, 196,
208, 219, 250, 105, 114

Genabea (Tul.), 357, 358

Genea (Vitt.), 358

General bundle-sheath, 109

Genuflexion, 265

Geocalycese, 162

Geocalyx (Nees ab Esenb.), 164

Germ-cell, 179

Germ-filament, 20

Germ-tube, 314, 325, 326, 327, 328, 329, 333,
35i, 352, 373, 385, 389, 390, 293, 299

HAL
Gigartina(Lmx.), 208, 169

— mamillosa (Ag.), 169
Gigartinaceae, 203, 208, 169, 185
Gills, 303, 319-321

Giraudia (D. & S.), 239, 247, 212

— sphacelarioides (D. & S.), 249, 212
Girdle, 420, 353, 354
Girdle-band, 268

Girdle-view (diatoms), 420, 354
Gland, 76, 67
Glaucocystis (Itzig.), 410
Glebe, 395, 397, 398, 399, 325, 329-331
Gleichenia (Sw.), 77, 85, 60
Gleicheniaceae, 85, 60
Glochid, 30, 13

Glochiococcus (Lagerh.), 417, 346
- anglicus (Benn.), 346

Gkeocapsa (Ktz.), 417, 440, 446, 447, 448, 449,
279

— fenestralis (Ktz.), 440
Gloeochaete (Lagerh.), 447
Gloeocystis (Nag.), 300, 417, 419, 448
Glceothece (Nag.), 447, 376

— granosa (Rabh.), 376
Gloeotrichia (Ag.), 436

— natans (Thur.), 435

— punctulata (Thur.), 436
Glomerule, 213
Glossopode, 50
Glycogen, 308, 355, 357
Gomphonema (Ag.), 424, 354, 356

— constrictum (Ehrb.), 354B, 356
Gonatonema (Wittr.), 261, 263

— notabile (Wittr.), 263
Gonatozygon (de By.), 271
Gongrosira (Ktz.), 284

— de Baryana (Rabenh.), 280

Gonium (Mull.), 186, 299, 302

Gonoplasm, 325, 328

Gottschea appendiculata (Nees ab Esenb.), 133

Gracilaria (Grev.), 199, 201, 208, 178, 187

— compressa (Ag.), 178

— confervpides (Grev.), 209, 187

— lichenoides(L.), 210
Graphiola (Port.), 350
Grasses, 350, 364, 376, 385
Grateloupia (Ag.), 208
Griffithsia (Ag.), 199, 204
Grimmia (Ehrh.), 149
Gulf-weed, 232, 236, 211
Gum-cell, 58, 76, 123
Guttulina (Cienk.), 405, 406

— protea (Fay.), 406

Gymnoascus (Baranet.), 359, 360, 361, 367, 368,

369. 37°) 378

Gymnocarpous Lichens, 356
Gymnogramme (Desv.), 16, 67, 83, 85, 58
- leptophylla (Desv.), 65
Gymnomitrium (Neesab Esenb.), 164
Gymnopodal shoot, 176
Gymnosperms, 12, 13, 14, 15, 52, 1, 3
Gymnosporangium (DC.), 386
Gymnostomous, 135, 147
Gyrolith, 183

HADROME, 19
Haematococcus (Ag.), 416

— Butschlii (Blockm.), 417
Halidrys (Grev.), 232, 235, 206

— siliquosa (Lyngb.), 206
Halimeda (Lmx.), 289, 258

— Tuna (Lmx.), 258

464

INDEX

HAL

Halosphasra (Schm.), 411, 337
- viridis (Schm.), 337
Halymenia (Ag.), 208
Hapalocystis mirabilis (Sorok.), 347
Hapalosiphon (Nag.), 439, 441, 36Y

— byssoideus (Kirchn.), 367
Haplomitrium (Nees ab Esenb.), 156, 161
Haplospora (Kjellm.), 249

Hard Fern, 72

Hauckia (Brzi.), 413

Haustorium, 309, 323, 326, 340, 350, 362, 378,

269, 285, 296

Hawlea Miltoni (Stur),94
Hedwigia (Ehrh.), 149
Helicpstylum (Cord.), 339
Helminthocladia (Ag.), 211
Helminthocladiaceae, 189, 211, 175, 189-191
Helminthostachys (Kaulf.), 98, 99, TOO
Helvella esculenta (Pers.), 278
Hepatic'as, 135, 156, 132-159
Heracleum sphondylium, 348
Hermonitis (L.), 85

Heterocyst, 427, 430, 431, 434, 438, 359, 362
Hetercecism, 383
Heteromeronsthallus, 320
Heterophyadic Equisetaceae, 113
Heterosporous Vascular Cryptogams> J3, I5,

20, 21, 5-33

Hibernating spores (Fungi), 315
Hibiscus, 340
Hildenbrandtia (Nard.), 190, 191, 193,210,211,

188

— prototypus (Nard.), 188

— rivularis (Ag.), 211

Himanthalia (Lyngb.), 228, 232, 23?, 205

— lorea(Lyngb.), ^05
Homoiomerous thallus, 321
Homophyadic Equisetaceae, 113
'Honey-dew,' 376

Hookeria (Sm.), 149

Hoop, 420

Hops, 364

Hormactis (Thur.), 436

Hormidium (Ktz.), 279

Hormiscia (Aresch.), 277

Hormogone, 427, 429, 431, 435, 438, 442, 445

Hormospora (Brdb.), 414, 344

— mutabilis (Brdb.), 344
Horse-tails, 100, 113, 124
House-fly, 343, 378

Hyaline hair. 226, 275, 433, 199

Hyaloplasm, 403

Hyalrtheca (Ehrb.), 187, 268

Hybridism, 145, 235

Hydneas, 393

Hydnobolites (Tul.), 357, 358

Hydnocystis (Tul.), 358

Hydnotria (B. and Br.), 358

Hydnum (L ), 392

Hydrianum (Rabh.), 413

Hydroclathrus (Bory), 245

Hydrocytium (A. Br.), 413

Hydrodictyeae, 277, 291, 296, 409 260

Hydrodictyon (Roth), 186, 296, 410, 413, 260

— utriculatum (Roth), 260
Hydrolapathum (Rupr.), 193, 196, 208, 71

— sanguineum (Stackh.), 171
Hydropteridea;, 21

Hydrurus (Ag.), 188, too, 256, 257, 232

— penicillatus (Ag.), 232
Hygroscopic properties, 171
Hymenium, 355, 357, 368, 373, 376,

3^,393,394,395,396,-

Hymenogaster (Vitt.), 395

Hymenogastreae, 395, 396, 398
Hymenomycetes, 388, 395, 266, 270, 273, 319-

Hymenophallus (Nees ab Esenb.), 398
Hymenophyllaceae, 16, 17, 18, 19, 64, 66, 67,

70, 71, 73, 76, 80, 81, 86, 121, 122, 61-64, 93
Hymenophyllum (L.), 86, 87, 88, 62-64
'— tunbridgense (Sm.), 62
Hypertrophy, 324, 326, 327
Hypha, 228, 306, 208-210, 267, 273, 281, 282,

285, 300, 307, 308, 317, 322
Hypnea (Lmx.), 209
Hypneaceae, 208

Hypnosperm, 225, 227. 266, 283, 295, 296
Hypnosporange, 285
Hypnospore, 262, 281, 284, 300
Hypnum (Dill.), 149

— populeum (Ssv.), 113, 118
Hypochnus (Fr.), 389, 266

— centrifugus (Tul.), 266
Hypocopra (Fckl.), 361
Hypodermal tissue, 107
Hypothece, 355, 360, 361, 370, 308
Hypoxylon (Bull.), 373
Hysterinea;, 356

ILEODICTYON(TU!.), 398

Impotent antherids 332

Impregnating tube, 324, 332, 286

Inactis (Ktz.), 441, 444

Indusium, 24, 29, 50, 73, 79, 86, 121, 19, 32, 59,

63, 93
Inflorescence, 134, 158, 170, 104, 106, 109, 131,

150, 151, 156, 157

Infusoria, agents in fertilisation, 199
Innovation, 85, 133, 139, 151, 157
Intercalary growth, 241

— surface-growth, 222, 200
Internode, 102, 174, 81, 165, 168
Intine, 325, 337, 339, 349, 351
Involucre, 85, 94. no, 159, 165, 171, 59
Involution-forms (Bacteria), 451
Iodine, 190, 236, 244

' Irish moss,' 210
Isactis (Thur.), 436, 365

— plana (Thur.), 365
Isinglass, 210
Isocystis (Brzi.), 432
Isoe'tese, 21, 47, 119, 28-33
Isoetes(L.), 19, 38, 47, 52. 119, 28-33

— lacustris (L.), 28-33
Isoetites (Schmp.), 119
Isogamous reproduction, 272
' Isospore/ 285

Isosporous Vascular Cryptogams, 12, 15, 20,

53,34-85
Isthmus, 270

JAPANESE isinglass, 210
Jungermannia (L.). 164, 132, 138, 142

— barbata (Schreb'), 138

— bicuspidata (L.), 142

— nemorosa (L.), 132
Jungermanniaceas, 159, 160, 172, 132-142

KALLYMENIA (Ag.), 208
Kaulfussia (Bl.), 78, 92, 93, 94, 95
Kelp, 190, 236, 244
Kickxella (Coem.), 341
Kieselguhr, 424

INDEX

465

LAB

LABIAT.-E, 364
Labium, 51

Laboulbenia flagellata (Peyr.), 312
Laboulbenieze, 378, 312
Lactarius (Fr.), 394
:una, 105, 81

MAS

Laci

Lagenidium (Schenk), 330, 331
Lamella, 393, 394, 153, 273, 3" '
Lamina, 50, 230, 242

19-321

Laminaria(Lmx.), 239, 304, 215

— digitata (Lmx.), 244

— saccharina (Lmx.), 215
Laminariaceae, IQO, 230, 236, 239. 241, 242, 304,

213-217
Lamprothamnus (A. Br.), 182

— alopecuroides (A. Br.), 176
Lastrea (Presl), 85

Lateral conjugation, 260, 265, 235, 238
Lathyrus, 364
Laticiferous hyphae, 394
Laudatea(Johow), 319
Laurencia (Lmx.), 209
Laver, green. 219

— purple, 217

Leaf-sheath, 102, 105, 124, 81, 83
Leathesia (Gray), 241
Leiodermaria (Ren.), 117, 89
Leiodermarieae, 117, 89
Lejeunia (G. & L.), 164
Lejolisia(Born.), 201, 209, 177

— mediterranea (Born.), 177
Lemanea (Bory), 191, 196, 214, 192

— fluviatilis (Ag.), 216

— nodosa (Ktz.), 192
Lemaneaceae, 189, 195, 214, 192
Lemna, 432

Lenticel. 93

Lepidodendreae, 115, 87, 88
Lepidodendron (Sternb.), 115, 87, 88
Lepidophloios (Sternb.), 116
Lepidophyllum (Brongn.), 88
Lepidostrobus (Brongn.), 115, 116, 88

— Brownii (Schmp.), 116, 88
• — dabadianus (Schmp.), 116

— ornatus (Hook.), 88
Lepidozia (Dum.), 164
Leptochaete (Brzi.), 436
Leptpchrysomyxa (de By.), 386

— Abietis (Ung.), 386

Leptogium microphyllum (Ach.), 307, 308

Leptome, 19

Leptophloem, 146

Leptopuccinia Dianthi (Schroet. ), 386

— Malvacearum (Schroet.), 386
Leptopuccinieae, 386
Leptosira (Brzi.), 280
Leptothrix (Ktz.), 4, 440, 445, 451

— muralis (Ktz.), 440

— parasitica(Ktz.), 440
Leptoxylem, 146
Lessonia (Bory), 244, 214

— fuscescens (Bory), 214
Leucobryum (Hampe), 138, 139, 149
Leucochytrium (Schroet.), 347
Leucodon (Sch\v.), 149
Leuconostoc (Van Tiegh.), 433, 455
Liagora (Lmx.), 194, 211
Lichen-fungi, 317, 318, 361

Lichens, 222, 279, 318, 356, 419, 441, 448, 449,
279-284, 307, 308

— discocarpous, 370

— gymnocarpous, 356
Licmophora (Ag.), 426
Lid-cell, 17, 158
Ligulatae, 38, 44

.), 85, 58

Ligule, 38, 44, 51, 31, 32

Lindsaya (D

Lip-cell, 79,

Lithoderma (Aresch.), 190, 251, 225

— fatiscens (Aresch.), 225
Lithophyllum (Phil.), 206
Lithothamnion (Phil.), 206
Liverworts, 135, 156, 160
Lobospira (Thur.), 254
Lomaria(Willd.), 83,85

— spicant (Desv.), 72
Lomentaria (Gaill.), 209
Lomentariaceae, 209
Lophoclea (Dum.), 164
Loxsoma (R. Br.), 86, 87, 121
Lucern, 364

Luminosity of fungi, 316
Lunularia (Mich.), 157, 170, 171
Lupins, 364
Lychnothamnus (Leon.), 182

— stelliger (A. Br.), 176
Lycoperdaceae, 395, 396, 398, 399
Lycoperdon (Tourn.), 308, 395
Lycopodiaceae, u, 15, 16, 18, 19, 53, 34-41
Lycopodieae, 53, 118, 34-39
Lycopodites (Brongn.), 118

— Stockii (Kidst.), 118

Lycopodium (L.), 19, 20, 53, 56, 61, 34-37, 39

— albidum (Bak.), 59

— annotinum (L.), 54, 34, 39

— cernuum (L.), 54, 61, 35

— clavatum (L.), 56, 61, 37

— inundatum (L.), 53

— Phlegmaria (L.), 55, 118, 36
Lygodium (Sw.), 71, 77, 90, 91, 69

— palmatum (Sw.), 69
Lyngbya(Ag.), 441, 444, 445, 449, 371

— aestuarii (Liebm.), 37i

— antliaria (Hansg.), 445
Lyngbyese, 441, 445

MACROCYSTIS (Ag.), 239, 240, 244, 213, 217

— pyrifera (Ag.), 213, 217
' Macrosporange,' 7

' Macrospore,' 7

Macrosporium Sarcinula (Berk.), 374

' Macrozoospore,' 7

Madotheca (Dum.), 157, 164

Male conceptacle, 233, 208

' — fern,' 72

— filament, 266

— inflorescence, 104, 150, 152, 157

— prothallium, 15, 103, 78
Mantle-cells, 36, 80, 99, 104
Manubrium, 175, 177, 163
Marattia (Sm.), 91, 94, 95, 70, 71

— cicutsefolia (Kaulf.), 93, 95
Marattiaceae, 20, 21, 64, 65, 74, 77, 78, 79, 81,

91, 121, 122, 70, 71, 94
Marchantia (L.), 157, 170, 171, 149 -151, 153-

159

- polymorpha (L.), 157, 149-151, 153-159
Marchantiaceae, 133, 157, 160, 167, 149-159
Alarchesettia spongioides (Hauck), 210
Marsilea (L.), 33, 37, "4, 4, 6, 14, 15, 17, 19

— Drummondii (R. Br.), 38

— quadrifolia (L.), 34, 6

— salvatrix (L.), 14, 15, 17, 19
Marsileaceae, 12, 13, 25, 31, 4-6, 14-19
Marsilidium (Schenk), 114
Martensella (Coem.), 341
Massaria (De Not.), 356

Massula, 25, 30, 13

Mastigobryum (Nees ab Esenb.), 164

H H

466

INDEX

MAS

NOS

Mastigocladus (Cohn), 439, 441

Mastigocoleus (Lagerh.), 439, 440, 441

Mastogloia (Thw.), 424, 426

Mazaea (Born.)) 440

Mechanical system, 138, 171

' Medulla,' 118, 124, 280

Medullary system, 76, 228, 242, 249, 321, 271

Megasporange, 7, u, 22, 277, 7, 18, 19, 26, 27

Megaspore, 7, n, 15, 20, 22, 118, 155, 7-9, 14-

16, 1§: 20, 29, 125
Megazoosporange, 260

Megazoospore, 7, 218, 273, 296, 410, 196, 260
Melampsora populina (Jacq.), 386
Melanospermeae, 235, 237
Melanospora (Cord.), 359, 360, 370
Melobesia (Lmx.), 193, 194, 196, 206, 182, 184

— membranacea (Lmx.), 182

- Thureti (Born.), 184
Melobesiaceae, 191
Melosira (Ag.), 424
Meridion (Leibl.), 426, 357

— constrictum (Ralfs), 357
Merismopedia (Mey.), 418, 446, 447, 448
Merispore, 6

Mercensia (Willd.), 77, 85
Merulius lacrymans (Fr.), 309
Mesocarpacese, 187, 258, 259, 260, 233-235
Mesocarpus (Hass.), 260, 262, 263, 330,233, 235

— neaumensis (Benn.), 261
parvulus (Hass.), 233

— pleurocarpus (de By.), 235
Mesoglceaceae, 239, 247, 220
Metzgeria (Cord.), 164
Meum athamanticum, 348
Micrandres, 225, 201, 202
Micrasterias(Ag.), 268, 239

— rotata(Grev.), 239
Microchaete (Thur.), 436

- - diplosiphon (Gom ), 434
Micrococcus (Cohn), 450, 379
Microcoleus (Desm.), 429, 441. 444
Microcyst, 404

Microcystis (Ktz.), 446, 447, 449, 377

— marginata (Meneg.), 377
Microspora (Thur.), 276, 242

— floccosa.OThur.), 242

Microsporange. 7, n, 22, 277, 7, 11, 18, 19, 26,
32,33

licrospore, 7, n, 12, 2
7, 11, 18, 20, 30, 125
Microthamnion (Nag.), 280
Microzoospore, 218, 277, 410
Mildew of corn, 383
Mischococcus (Nag.), 412, 339

— confervicola (Nag.), 339
Mitremyces (Nees ab Esenb.), 399
Mnium (L.), 138, 140, 149
Mohria (S\v.), 90, 91
Monadopsis (Klein), 405

Monas amyli (Cienk.), 405
Monoblepharideas, 331, 290
Monoblepharis (Cornu), 4, 331, 290

— sphaerica (Cornu), 290
Monoclea (Hook.), 164, 143

— Forsteri (Hook.), 143
Monocleaceae, 164, 143
Monosiphonous, 192, 195
Monospora (Sol.), 196
Monostroma (Thur.), 217, 218, 219, 198

— bullosum (Thur.), 198
Moonwort, 100
Morchella (Dill.), 356
Mortierella (Coem.), 338, 339

— nigrescens (Van Tiegh.), 338

— Bostafinskii (Bref.), 338

Mosses, 135, 14:

Mosses, 135, 145

Mougeotia (de By.), 262, 264, 267, 330

— calcarea (Wittr.), 262
Moulds, 366

Mucilage, 69, 220, 221, 238, 256, 257, 263, 269,

283, 298, 398, 248, 330
Mucilage-cell, 58, 76, 89, 92, 168, 67, 154
Mucilaginous sheath, 259, 267, 268, 274, 298,

428, 430, 434, 437, 440, 441
Mucor (Mich.), 4. 307, 339,340, 350, 381, 293,

296

— Mucedo (L.), 293, 296

— • racemosus (Fres.), 339
- tenuis (Lk.), 338

Mucoreae, 337, 339, 340

Muccrini, 4, 308, 315, 316, 335, 341, 342, 344,

345, 377. 378, 293-296

Multilocular zoosporange, 187, 237, 212, 227
Multinucleatae, 186. 280, 248-258^
Musci, 135, 136, 102-131
Muscineae, 2, 132, 102-159
Mushroom, 311, 320
Mutinus caniniis (Fr.), 308, 329

m' 389' 275'

Mycetozoa, 305, 401, 456, 332-335

— doubtful, 405
Mycoidea (Cunn.), 222

— parasitica (Cunn.), 222
Mycorhiza, 310
Mylitta(Fr.), 309
Myrionema (Grev.), 241
Myxomycetes, 401,406, 332-335
Myzocytium (Schenk), 330

NARDOO, 38

Navicula (Bory), 420, 422, 424, 357

— rhomboides (Khrb.), 357

Neck, 16, 26, 39, 86. 68, 143, 179, 109, 148, 158
Neck-canal-cell, 16, 27, 39, 69, 159, 10
Neck-cell, 26, 68, 10
Neckera (Hedw.), 149
Nectria cinnabarina (Fr.), 267
Nemalieae, 192, 195, 199, 211, 175
Nemalion (Ag.), 211, 213, 175

— multifidum (Ag.), 175
Nemastoma (Ag.), 208
Nemathece, 196, 199, 202
Nematodonteae, 148

(Carruth.), 304

Nematophycus (Carru
Neomeris (Lmx.), 287,

254

— Kelleri (Cram.), 287, 254
Nephrocytium (Nag.), 414, 343

— Nagelii (Grim), 343
Nephrodium (RichA 85
Nephrolepis (Sch.), 77, 85
Nereocystis (Post.), 240, 242, 244
Neutral zone, 175, 163
Nidularieae, 397, 327, 328

Nitella (Ag.), 175, 176, 179, 182, 163, 165, 166
- flexilis (Ag.), 163, 165, 166
Nitelleae, 173, 182, 163, 165, 166
Nitophyllum (Grev.), 196, 208, 173

— punctatum (Harv.), 173
Xitzschia (Hass.), 426
Node, 102, 173, 421, 165, 168
Nodularia (Mert.), 430, 433
Nodule, 421

Nostoc (Vauch.), 28, 165, 171, 429, 430, 431,
43*, 433, 353 f 9

— commune (L.), ooo

— hyalinum (Benn.), 359

— muscoruin (Ag.), 431

— parietinum (Rabenh.), 440

INDEX

467

NOS

Nostocaceae, 185, 4*7, 428, 430, 455, 456, 358-362

Nostochineae, 186, 427, 428, 358-373

Nothoclama (R. Br.), 85

Notommata, 284

Nuclei, plurality of, 186, 187, 188, 194, 272, 275,

281, 284

Nuclearia (Cienk.), 405
Nullipore, 206
Nummularia(Tul.), 373

OBELIDIUM (Nowak.), 346

Octaviana asterosperma (Vitt.), 324

'Octospore,' 217

CEdogoniaceae, 188, 220, 222, 200-202

CEdogonium (Lk.), 222, 223, 226, 200, 201

— ciliatum (Mass.), 201

— gemelliparum (Hass.), 201
Oidium Tuckeri (Berk.), 364
Olfersia (Radd.), 80
Oligocarpia Lindsaeoides (Stur), 94
Olpidiese, 344, 345, 346, 347
Olpidiopsis fusitormis (Cornu), 346

— Saprolegniae (Fisch.), 346
Olpidium (A. Br.), 347
Onions, 327

Onoclea (L.), So, 85

Onygena (Pers.), 358, 359

Ooblastema-filament, 202, 211, 215

Oogamous reproduction, 188

Oogone, 185 (see also under Algae and Fungi),

199, 201, 202, 210, 228, 248, 249, 259, 286, 290,

291

Oomycetes, 323, 332, 285-292
Oophyte, 10, 16, 132, 135
Oosperm, n (see also under Vase. Crypt.,

Muse., Char., Algae, and Fungi), 203, 210,

229, 248, 259, 286, 290, 291
Oosphere, 8 (see also underVasc. Crypt., Muse.,

Char., Algae, and Fungi), 4, 10, 15, 45. 109,

148, 158, 201, 203, 210, 229, 259, 286, 291
' Oosporange,' 237
' Qospore,' 8
' Oosporeae,' 3
Opercule, 135, 112, 117, 131
Ophiocytium (Nag.), 414

Ophioglossaceae, 13, 16, 20, 21, 81, 95, 123, 72-76
Qphioglossum (L.), 97, 98, 99, 100, 72, 76

— pedunculosum (Desv ), 96

— vulgatum (L.), 98, 100, 72, 76
Orthotrichum (Hedw.), 149

Oscillaria (Bosc.), 429, 441, 442, 443, 445, 368,
369

— aerugineo-coerulea (Ktz.), 443

— antliaria (Hansg.), 445

— dubia (Ktz.), 443
- Frolichii (Ktz.), 446

— princeps (Vauch.), 441, 443, 444, 369

— tenuis (Ag.), 446,368

Oscillariaceae, 427, 428, 429, 433, 437, 441, 455,
368-373

— movements of, 442
Oscillatorieae, 441

Osmunda (L.), 66, 67, 75, 89, 90, 65-68

— cinnamomea (L.), 90

— regalis (L.), 73, 90, 65-67
Osmundacese, 66, 75, 76, 78, 80, 81, 88, 65-68
Osmundites (Carruth.), 123

Ostiole, 207, 356, 182-184, 208, 209, 311
Ovulites (Lam.), 304
Oxymitra (Bisch.), 166

PACHYMA (Fr.), 309
Pachyphloeus (Tul.), 35£

Padina (Adans.). 254, 230, 231

— Pavonia (Gaill.), ^30, 231
Palaeopteris hibernica (Schimp.), 121, 93
Palaeostachys (Weiss), 128

Pale, 72

Palisade-cells, 321
Palisade-parenchyme, 19
Palmella(Lyngb.), 415, 417, 448

— cruenta (Ag.), 416

— nivalis (Hook.), 416

— prodigiosa (Mont.), 416

— uvaeformis (Ktz.), 276, 417
Palmellacese, 257, 415, 418, 419
Palmellin, 416

Palmelloid condition, 277, 409, 411, 412, 415,

Palmodictyon (Ktz.), 418
Pandorina (Ehrb.), 186, 299, 300, 263

— morum (Ehrb.), 263
Pandorineee, 186, 291, 299, 409, 263
Paraphyse, 55, 79, 87, 134, 142, 196, 233, 237,

244, 354, 355) 356, 358, 3?o, 37i, 372, 373, 374,
386, 388, 394, 36, 50, 106. 208, 209, 27b, 300,

Parasites (Fungi), 316, 317, 329, 383
.— (Bacteria), 454
Parasitic Algae, 249, 280, 284
Parsley-fern, 72

Parthenogenesis, 181, 267, 333, 338
Parthenosperm, 261, 262, 267
Parthenospore, 292
Pecopteris arborescens (Schl.), 124
Pediastreae, 186, 190, 291, 298, 418, 261, 262
Pediastrum (Mey.), 298, 26i, 262

— integrum (Nag.), 261
Pedicel, 80

Pedicel-cell, 177, 179, 233, 369

Pell;ea(Lk.),85

Pellia (Radd.), 162, 164, 136

— epiphylla (Cord.), 136
Peltate leaf, 28, 8, 9

— scale, 102, no, 2, 83
Pelvetia (Dene.), 235

Penicillium (Lk.), 312, 358, 359, 360, 366, 378

— glaucum (Lk.), 316, 367
Penicillus (Ktz.), 289
Penium (Breb.), 268, 241

— margaritaceum ( Brdb. ), 241
Perianth, 134, 141, 142
Pericarp, 180, 201, 221, 263, 199
Pericentral tubes, 192

Perichsste, 134, 141, 162, 109, 129, 131

Periderm. 430

Peridinieae, 410

Peridiolum, 397, 328

Peridium, 311, 357, 358, 395, 396, 397, 398, 399,

325, 328-331
Perigone, 142, 106
Perigyne, 159, 163, 171, 142, 158
Perinium, 160
Peripheral growth, 241
Periphyse, 356

Periplasm, 324, 325, 327, 331, 332, 286
Peristome, 135, 147, 110-112, 114, 118
Perithece, 355, 356, 362, 365, 370, 373, 374, 375,

378, 379, 311, 312
Peronospora (Cord.), 4, 323, 326, 327, 328, 329,

3?8

— arborescens (de By.), 286

— calotheca (de By.), 269, 285

— densa(Rab.), 327

— Ficaria; (Tul.), 327

— nivea (de By.), 327

— parasitica (de By.), 326, 327

— pygmaea (Ung.), 327

468

INDEX

PER

Peronospora Rumicis (Cord.), 327

— Schachtii (Fckl.), 327

— Schleideniana (Ung.), 327

— Trifoliorum (de By.), 327

— Viciae (de By.), 327

— viticola (de By.), 327

Peronosporeae, 4, 309, 312. 315, 323, 331, 332,

333, 377, 378, 269, 272, 275, 277, 285-289
Peronosporites (W. G. S.), 330

— antiquarius (W. G. S.), 330
Persistent cell, 444
Petalonema (Berk.), 438, 440
Peyssonelia (Dene.), 210
Peziza (Dill.), 356

— (Pyronema) confluens (Pers.), 369, 276, 300,
306

Phacidiaceae, 356

Phaeophyll, 230

Phaeosporeae, 187, 190, 230, 237, 212-232

Phaeothamnieae, 258

Phseothamnion (Lagerh.), 258, 276

Phaeozoosporeae, 237

Phalloideae, 395, 397, 329-331

Phallus (L.), 398, 399, 330

— impudicus (L.), 398, 330
Phascaceae, 136, 150, 121, 122
Phascum (L.), 140, 150
Phloem-sheath, 18, 59
Phlyctidium (A. Br.), 346
Phragma, 125
Phragmidium (Lk.), 386, 314

- incrassatum (Lk.), 314
Phycochromaceae, 426
Phycocyanin, 427, 442
Phyco-erythrin, 194, 217
Phycomyces (Kze.), 338, 339, 293

— nitens(Kze.), 293

Phycomycetes, 4, 5, 323, 352, 377, 381, 285-299

Phycophaein, 230, 240, 256

Phycoseris (Ktz.), 217

Phycoxanthin, 230, 421

Phyllade, 51

Phyllitis (Ktz.), 245

Phyllobium(Klebs), 284, 410

Phylloglossum (Kze.), 19, 53, 56, 59, 60, 61, 38

— Drummondii (Kze.), 61, 08
Phyllosiphon (Kiihn), 284
Phyllotaxis, 59, 99, 106, 139, 151, 194
Phyllotheca (Brongn.), 124, 96

— equisetiformis, 96
Physareae, 403

Physcia parietina (Nyl.), 279

Physiotium (Nees ab Esenb.), 161

Physma (Massal.), 372

Physoderma (Wallr.), 346

Phytophthora (de By.), 323, 327, 328, 332, 335,

272 j 277 , 289
— infestans (de By.), 314, 326, 327, 328, 272,

277, 289

omnivora (de By.), 327, 329
Pigment-spot, 223, 292, 300, 416
Pileus 286, f39i, 392, 393, 398, 399, 251, 252,

Pilini'a(Ktz.), 280

Pilobolus (Tode), 339

Pilularia (L.), 19, 33, 37, 114, 5, 16, 18

— globulifera (L.), 36, 5, 16, 18
Pinnularia (Ehrb.), 426, 353
-viridis(W. Sm.),353
Piptocephalideae, 340, 378, 295, 296
Piptocephalis (de By.), 340, 342, 295, 296

— Freseniana (de By. and Wor.), 295, 296
Pithophora Kewensis (Wittr.), 276, 245
Pithophoraceae, 187, 273, 276, 245

Pits in oogonial wall, 332

POL

Placenta, 25, 29, 35, 80, 86, 201
Placental cells, 209, 287
Plagiochasma (L. & L.), 171
Plagiochila (Dum.), 164
Plantago, 364

Plasmatoparous Peronosporeae, 327
Plasmode, 401, 402, 403, 404, 405, 406, 332, 333

— movements of, 403

- resting states of, 404
Plasmodiophora (Woron.), 405

— Brassicae (Woron.), 405
Platycerium (L.), 83, 85

— alcicorne (Desv.), 72, 77
Plaxonema (Tangl), 444
Plectonema (Thur.), 437, 438, 439
Pleomorphy of Uredineae, 383
Pleospora (Rabenh.), 361, 362, 374

— herbarum (Rabenh.), 374
Plerome-sheath, 18, 109
Pleuridium (Brid.), 150, 122

— subulatum (H abenh.), 122
Pleurocarpi, 149
Pleurocladia (A. Br.), 247
Pleurococcus, 279, 300, 417, 419
Pleurosigma (W. Sm.), 420, 426, 357

- lacustre (W. Sm.), 35Y
Plocamium (Lmx.), 196, 208

— coccineum (Huds.), 209
Plumule, 41

Podosphsera (Kze.), 360, 362, 378, 303

— Castagnei (de By. and Wor.), 364, 303

— Kunzei (Le"v.), 364

— pannosa (de By. and Wor.), 303
Pollen-grain, n, 12, 14, 3
Pollen-sac, 13, 1

Pollen-tube, n, 14, 3

Pollexfenia (Harv.), 194, 209

Pollinoid, 7, 185, 198, 199, 207, 254, 360, 361,

Polyedriaceae, 419

Polyedrium (Nag.), 290, 418, 419

Polygonum, 364

— Hydropiper, 351
Polyhedra, 296, 298, 299, 262
Polyides (Ag.), 202, 209
Polyphagus (Nowak.), 314, 346, 297

— Euglenae (Nowak.), 345, 297
Polyphysa (Lmx.), 288, 255

— peniculus (R. Br.), 255
Polypodiaceae, 64, 67, 75, 78, 79, 80, 81, 83,

121, 123, 42, 44-56, 58
Polypodies, 83, 84
Polypodium (L.), 77, 84, 85, 53, 58
•— leiorhizum (Wall.), 53
Polyporese, 303, 396, 322, 323
Polyporus (Mich.), 392, 396, 322, 323

— annosus (Fr.), 316

— igniarius (Fr.), 322, 323

— obvallatus (Berk, and Cooke), 396

— sulphureus (Fr.), 316

— volvatus (Pk.), 396
Polysaccum (DC.), 399

Polysiphonia (Grev.), 192, 193, 194, 201, 209,
170

— opaca (Zan.), 170
Polysiphonous, 192
Polyspore, 6

Polystichum angulare (Willd.), 60, 48
Polystigma (Pers.), 360, 372, 385
Polythrix (Zanard.), 437
Polj-trichaceae, 146

Polytrichum (L.), 138, 139, 142, 148, 149, 104,
107, 112, 117

— commune (L.), 104, 107, 117

INDEX

469

POL

Polytrichum piliferum (Schreb.), 112

Polyzonia (Suhr), 194

Pomeae, 386

Pore, 154, 187

Pores of Polyporeae, 393, 322

Porphyra (Ag.), 189, 191, 199, 216, 219

— vulgaris (L.), 217

Porphyraceas, 189, 190, 196, 198, 199, 216, 219,

Porphyridium cruentum (Nag.), 416
Potato-disease, 328
Pottia (Ehrh.), 147, 149
Prasiola(Ag.), 217, 219
Preissia (Cord.), 169, 170, 171
Primary node, 180

— root, 180, 168

Procarp, 198, 199, 213, 176, 187, 192
' Proembryo,' 177, 180
'Proembryonic branch,' 176
Progametange, 349, 298
Prolific cells, 276

Prolification, 69, 139, 142, 196, 289, 104, 171
Promycele, 325, 328, 329, 337, 338, 350, 351.

352, 362, 373, 385, 386, 391, 299, 614
Propagation, 8

Propagule, 196, 237, 250, 289, 223, 224
Prothallium, 10, 339 (see also underVasc. Crypt. .

Muse., & Char.), 4, 8, 9,14, 15, 20, 29, 34-36'

42, 43, 50, 65, 74, 78-80, 126, 168
Prothalloid branch, 176

— growth, 70, 48

86' 345) 4°9' 4IO) 4I5' 448'

RHI

u —

Protococcoideae, 186, 408, 409, 449, 336-352
Protococcus (Ag.), 186, 285, 409, 417, 448, 279,
345

— pluvialis (Ktz.), 345
Protomyces (Ung.), 4, 350, 352, 298

— macrosporus (Ung.), 348, 298
Protomycetaceae, 348, 298
Protomyxa (Haeek.), 405

Prot°neme, 133, 135, 136, 140, 214, 449, 105,

Protophloem, 59

Protophyta, 2, 3, 4, 186, 276, 407, 336-382

Protosalvinia (Daws.), 115

Protozoa, 456

Prozoosporange, 346, 297

Prunus, 364, 373

Psaronieae, 124

Psaronius (Cord.), 124, 95

Pseudo-bulbil, 70

Pseudo-cortex, 192, 212

Pseudocyst, 410, 427, 437, 441, 446

Pseudo-parenchyme, 249, 251, 307, 356, 358,

360, 366, 372, 384, 267
Pseudopode, 151, 154, 402, 403, 422, 443, 131,

332

Pseudo-ramulus, 434, 438, 364, 366
Pseudospora (Cienk.), 405
Psilophyton (Daws.), 119
Psiloteae, 21, 53, 61, 119, 40, 41
Psilotum (Sw.), 17, 18, 19, 20, 53, 61, 63, 40

— triquetrum (Sw.), 61, 40
Pteris (L.), 85, 46, 47, 54, 58

— aquilina (L.), 75, 76, 77, 82, 54

— serrulata (L. fil.), 69, 46, 47
Ptilophyton (Daws.), 118
Ptilota (Ag.), 194, 204
Puccinia (Pers.), 383, 385, 386

— coronata (Cord.), 314

— graminis (Pers.), 383. 274, 314, 315
- straminis (Fckl.), 314

Puff-ball, 311, 396
Pulvinus, 93

Punctaria (Grev.), 187, 241, 245

Punctariaceae, 239, 245

Pycnid, 362, 374

Pycnochytrium (de By.), 347

Pycnophycus (Ktz.), 235

Pycnospore, 362, 374, 375

Pyrenocarp, 355

Pyrenomycetes, 319, 355, 356, 370

Pyronema (Fckl.), 356, 359, 360, 361, 369, 370,

372, 378, 276, 306
— confluens (Tul.), 276, 306
Pythium (Pringsh.), 317, 324, 329, 330, 331,

332,335,
— Chl<

^hlorococci (Lohde), 329

— circumdans (Lohde), 329

— de Baryanum (Hesse), 329

— entophytum (Pringsh.), 329

— Equiseti (Sad.), 329

— gracile (Schenk), 329, 286

— intermedium (de By.), 329

— proliferum (de By.), 329

— vexans (de By.), 325, 329,377

QUATERNARIA (Till.), 373

RADIOLARIANS, yellow cells of, 318
Radula (Dum.), 162, 164, 137, 141

— complanata (Dum.), 137, 141
Ralfsia (Berk.), 241, 251
Ralfsiaceae, 239, 251, 225
Ramentum, 72
Ranunculus, 364

Raphe, 421, 353
Raphidium (Ktz.), 418, 351

— falcatum (Ktz.), 351
Reboulia (Radd.), 171

Receptacle, 80, 170. 232, 246, 149-151, 154, 156,

157; 205, 207, 219 "
Receptive spot, 69, 227
' Red snow,' 416
Rejuvenescence, 223, 274, 281
Renaultia (Stur). 122
Reproduction, 8
Reserve-system, 139
Resting-cell, 213, 264, 335, 339, 346, 347
Resting-sporanae, 333
Resting-spore, 223, 258, 276, 278, 281, 285, 298,

315, 344, 345, 350, 351, 352, 416, 427, 430,

436, 261, 361, 362
Resting-swarm-cell, 274
Resting-zoosporange, 346
Retrogression, 4, 407, 449
Rhabdonema (Ktz.), 423, 424
Rhacophyllum adnascens (L. & H.), 120, 92
Rhipidonema (Mattir.), 319
Rhizidieae, 344, 345
Rhizidium (A. Br.), 346
Rhizocarpeae, 18, 19, 21, 114, 4-19
Rhizoclonium (Ktz.), 276
Rhizoglossum (Presl), 99
Rhizoid, 16, 132, 139, 156, 174, 180, 222, 228,

239, 241, 242, 273, 277, 282, 285, 332, 340,

345 346, 363, 14, 43, 50, 65, 102, 163, 168, 250,

252, 256, 280, 318
Rhizome, 51, 72, 81, 86
Rhizomorph, 392, 270, 319
Rhizomorpha (Roth), 309

— fragilis (Roth), 319
Rhizophore, 45
Rhizophydium (Schenk), 346
Rhizopoda, 456
Rhizopus (Ehrb.), 339, 294

- nigricans (Ehrb.), 337, 294

470

INDEX

RHO

SOR

Rhodomela (Ag.), 209
Rhodomelaceae, 209, 170, 174
Rhodophyll, 194
Rhodospermeae, 191
Rhodospermin, 194
Rhodosporeae, 191
Rhodymenia (Grev.), 208, 186

— binda(Ktz.), 196

— palmata (Grev.), 209

— Palmetta (Grev.), 186
Rhodymeniaceae, 208, 171, 186
Rhytidolepidae, 117

Riccia (L.), 165, 166, 148

— glauca (L.), 148
Ricciacex, 160, 165, 146-148
Ridge, 100, 106, 124, 129, 81

Riella (Mont.), 156, 159, 165, 166, 146 .

— helicophylla (Mont.), 146
Rivularia(Roth), 436, 363

— fluitans (Cohn), 436

— polyactis (Hauck), 363
Rivulariaceae, 185, 427, 428, 433. 445, 363-365
Roccella tinctoria (DC.), 284

Roestelia (Reb.), 386

Root-cap, 18, 78, 109

Root-hair, 18, 78

Rotation of protoplasm, 175, 163

' Royal Fern,' 73, 90, 66, 67

Rozella (Cornu), 345, 347

Rumex, 364

Russula adusta (Fr.), 308

Rye, 310

Rytiphloea (Ag.), 194, 209

SACCHAROMVCES (Meyen), 4, 380, 381, 268, 313

— albicans (Reess), 380

— cerevisiae (Meyen), 380, 268, 313

— ellipsoideus (Reess), 380

— Mycoderma (Reess), 380

— Pastorianus (Reess), 380
Sacconema (Brzi.), 437
Sacheria (Sir.), 214
Saddle, 51

Salicaceae, 310
Salmon-disease, 332
Salvinia(L.), 17, 18, 25, 31, 7-11

— natans (I..), 7-11
Salviniaceae, 12, 13, 20. 25, 114, 7-13
Saprolegnia(Nees ab Esenb.), 4, 332, 333. 334,

335, 338, 339, 346, 347
Saprolegmeae, 4, 308, 312, 324, 332, 338, 347,

377, 291, 292

Saprophytes, 315, 316, 317, 329, 366, 454
Sargasso Sea. 232
Sargassum (A?.), 230, 232, 235, 211

— bacciferum (Ag.), 232. 236, 211
Scalariform conjugation, 260, 265, 233,234, 236,

237

— tracheide, 18, 76, 98, 123
Scenedesmus(Mey.), 303, 418, 352

— obtusus (Mey.), 352
Schizaea(Sm.), 90, 91
Schizaeaceae, 64, 80, 81, 90, 122, 43, 69
Schizochlamys (A. Br.), 417, 348

— gelatinosa (A. Br.), 348
Schizogonium (Ktz.), 279
Schizomycetes, 433, 449, 379-382
Schizoneura (Schimp.), 124
Schizophyceae, 408, 336-378
Sciadiaceas, 410, 411
Sciadium (A. Br.), 411, 336

— arbuscula (A. Br.), 336
Sclerenchyme. 75, 123, 53, 54
Scleroderma (Pers.), 397

Sclerosis, 58, 309, 39

374' 376' 392' 4°4'

Sclerotinia (Fckl.), 373

— Fuckeliana (de By. and Wor.), 361, 374

— sclerotiorum (de By.), 360, 361, 373, 374,

Sclerotium (Tode), 310
Scolecopteris (Stur), 122, 94

— polymorpha (Stur), 94
Scolopendrium (Sm.), 81, 85, 58
Scutiform leaf, 28, 8, 9
Scyamina (Van Tiegh.), 295
Scytonema (Ag.), 438, 441, 445, 279
Scytonemaceae, 303, 427, 428, 433, 437, 366,

367

Scytonemeae, 438, 441, 445, 366, 367
Scytonemin, 427, 437
Scytosiphon (Ag.), 239, 241, 245

— lomentarium (Ag.), 246
Scytosiphonaceas, 245
Seaweeds, 184, 190, 191, 235, 237
Sebacina (Tul.), 389
Secondary capitulum, 178, 163

— embryo-sac, 14, 52, 3

— growth in thickness, 49, 116, 125

— markings, 420, 353

— prothallium, 39
Secotium (Kze.), 395

— erythrocephalum (Tul.), 396
Secreting system, 139
Seftenbergia (Cord.), 122, 94

— ophidermatica (Stur), 94
Seirospora Griffithsiana (Harv.), 204
Seirospore, 196, 204, 180

Selaginella (Spring), 19, 20, 38, 39, 47, 20-27

— caulescens Spr.), 20

— denticulata (Lk.), 24

— inasqualifolia (Spr.), 22, 23, 25-27

— Martensii(Spr.), 20, 21
Selaginellaceae, 12, 13, 18, 19, 38, 115, 130,

20^33, 87-91

Selaginelleae, 38, 39, 20-27
Selenastrum (Reinsch), 186, 303
Seta, 134, 144, 146, 110, 112
Sewage-fungus, 454
Sheath, 50, 428, 430, 434, 437
Shepherd's Purse, 326
Shield, 177, 163

Side-view (of diatoms), 421, 354
Sieve-hypha, 244
Sieve-plate, 240, 244, 217
Sieve-tube, 18, 58, 240, 244, 217
Sigillaria, 117, 118, 89, 91
Sigillariostrobus, 117, 118
Silica, 102, 107, 419, 420
Siphon, 192
Siphoneas, 186, 280, 281, 290, 308, 410, 248,

249
Siphonocladaceae, 186, 190, 279, 280, 281, 288,

304, 411, 256-258
Siphonocladus (Schr.), 289
Sirogonium (Ktz.), 264, 265, 267
Sirosiphon {Ktz.), 439, 441, 449
Sirosiphoneae, 437, 438, 439, 441
Solenites(L. & H.), 119
Sorastreae, 186, 291, 302, 414, 418, 264, 265
Sorastrum (Ktz.), 186, 302, 264

— spinulo^um (Nag.), 264

Sordaria (Ces. and De Not.), 354, 359, 360,

37°

Sorede, 319, 282
Sorophore, 37, 19
Sorosporium (Rud.), 350, 352

— Saponariae (Rud.), 351

INDEX

47i

Sorus, n, 20, 24, 72, 79, 94, 122, 196, 2^7, 244,

251, 347, 19, 58, 59, 71, 218
Spatoglossum (Ktz.), 254
Special bundle-sheath, 109
' Sperm,' 7, 8
' Sperm-cell,' 8
' Spermatia,' 7, 360
' Spermatozoid,' 8

Spermocarp, 180, 221, 165, 167, 168, 199
' Spermogone,' 7, 360
Spermothamnipn (Aresch.), 209, 176

— hermaphroditum (Nag.), 176
Sphacelaria (Lyngb.), 249, 223, 224

— cirrhosa (Ag.), 223, 224
Sphacelariaceae, 237, 239, 241, 249, 223, 224
Sphacele, 249, 223

Sphacelia (Lev.), 376, 309
Sphacelotheca (de By.), 352

— Hydropiperis (de By.), 350
Sphaerobolus (1 ode), 399
Sphserocarpus (Mich.), 160, 166, 147

— terrestris (Sm.), 147
Sphaeroccccaceae, 208, 178, 187
Sphaerococcus (Stackh.), 208
Sphaerogonium (Rostaf.). 444
Sphaeroplea (Ag.), 227, 203, 204

— annulina (Ag.), 226, 203, 204
Sphasropleacese, 188, 220, 226, 203, 204
' Sphaerosp re,' 195

Sphaerozyga (Ag.), 430, 433

Sphagnaceae, 132, 136, 139, 142, 144, 145, 151

125-131

Sphagnum (L.), 138, 156, 172,125-131
- acutifolium (Ehrh.), 125-127, 129-131

— cymbifolium (Dill). 128

— squarrosum (Pers.), 131
Sphenoglossum (Emm.), 114
Sphenophylleae, 129, 130, 101
Sphenophyllum (Brongn.), 129, 130, 101
Sphenopteris crenata(L. S: H.), 120, 92
Spherpcrystal. 93

Sphyridium (Plot.), 361
Spinellus fusiger (Van Tiegh.), 338
Spiral bands, 152
Spirillum (Ehrb.), 450, 451, 382
Spirpchaeta (Ehrb.), 451

Spirogyra (Lk.), 4, 264, 265. 266, 267, 330, 342,
2367238

— bellis (Mass.), 238

— crassa(Ktz.), 264

— porticalis (Vauch.), 236
Spirulina (Lk.), 429, 441, 370

— tenuissima (Ktz.), 370
Splachnidium (Grev.), 235, 236
Splachnum(B. & S.), 149

— ampullaceum (L.), 116
Splenic fever, 452, 454
Spongiocarpese, 209
Spongocladia (Aresch.), 276, 290
Spongodieae, 289
Spontaneous generation, 450

— movement, 415, 427, 431, 442

Spore-sac, 147, 112

SP°rid' 6, 314, 350, 35i, 352, 362, 373,385, 386

390, 299, 314

Sporiferous filaments, 192
Sporocarp, n, 353 (see also under Vase. Crypt.

Algat, and Sporocarpeae), 5-7, 12, 18, 19

Ol, ^\J) "T-Lj «J«J. UU, UU— VJW, Wy \J*~i, I AJ I t_j, I Wj I ^',

83, 93, 110, 111, 114-118, 122, 124, 131, 133,

134, 137, 145, 158, 293, 334
— dehiscence of, 79, 94, 135, i55» I59, 55
Sporangiole 339

Sporangiophore, 328, 337, 339, 28'
Sporangiospore, 6
Sporangites (Daws.), 115
Spore, 5 (see also under Vase. Crypt., Muse.,

Algae, Fungi, Mycet., and Prot.), 37, 84, 85,

158, 181, 245. 249, 272, 275, 303, 317, 318,

332, 335, 361, 362, 379-381

— origin of, 359
Sporocarpeas, 353, 300-331
Sporocarpon (Williams.), 114
Sporochnaceae, 245
Sporochnus (Ag.), 241, 246, 219

- pedunculatus(Ag.), 219
Sporodinia (Lk.), 338, 339

— grandis (Lk.), 337
Sporogenous tissue, 20. 46, 33

Sporogone, 134, 136, 144, 159, 163, 107, 110,

131, 142, 143, 145, 148, J.56, 158
Sporophore, 309, 325, 327, 328, 336, 337, 340,

343, 363, 365, 367, 374, 388, 389, 404, 272,

275, 288, 293, 296, 303, 304, 327-329, 33a
Sporophore (compound), 391, 392, 393, 395,

396, 397, 398, 273, 319, 320
Sporophyll, 46, 51, 72, 99, IIO, 116, 32, 72, 75,

76, 83, 88

Sporophyte, 10, 17, 132, 135, 159
Sporophytic budding, 69

SP0r°uti"g> 307, 3i4, 339, 352, 380, 381, 389,

268, 313

Spyridia (Harv.), 193, 209
Spyridiaceae, 209 ^

Squamariaceae, 189, 190, 191, 202, 210, 188
Stag's-horn-moss, 61
Staurastrum (Mey.), 269, 270, 239, 240

— Arachne (Ralfs), 239
teliferum (Ralfs), 240

Stauroneis (Khrb.), 426
Staurospermum (Ktz.), 260, 263, 234

— capucinum (Ktz.), 263

— gracillimum (Hass.), 234
Stemmatopteris (Cord.), 124, 95

— insignis (Cord.), 124
Stemonitis fusca (Roth), 334
Stephanosphsera (Cohn), 186, 299, 301
Stephensia (Tul.), 358
Stereocaulon ramulosum 'Ach.), 279
Sterigma, 86 340 367, 370, 372, 376, 384, 386,

389, 394, 2/5, 304
Stichid, 196, 174
Stictosphseria (Tul.), 373
Stigeoclonium (Ktz.), 276, 284, 417
Stigma, 133, 143
Stigmaria, 118, 90, 91

— ficoides (Brongn.), 118, 90
Stigmatic cell, 17, 27, 133, 143, I58, 15, 109
Stigmatomyces (Karst.), 378

- Baeri (Peyr-), 312

- Muscat (Karst.), 312
Stigonema (Ag.), 439, 441, 449, 366
- compactum (Kirchn.), 440

— minutum (Hass.), 366
Stigonemeae, 437, 438, 445, 366

Stipe, 230, 239, 241, 242, 286, 391, 319, 320

Stipule, 92, 174

Stcechospermum (Ktz.), 254

Stolon, 78, 133, 139

Stornate 19, 72, 78, 93, 107, 144, 169, 23, 82,

Stomium, 79, 55

Stoneworts, 181

Strand-mycele, 309

Streblonema (Derb.), 239

Stroma, 350, 352, 355, 356, 370, 375, 311

Struthioptens (L.); 66

— germanica (L.), 66, 69, 77
Struvea (Sond.), 289

472

INDEX

Stylospore, 339, 362
Stypocaulon (Ktz.),

STY
249

otypocauion ^ r^iz.), 249

Subhymenial layer, 355, 368, 372, 393, 394,

Submerged leaf, 28, 7, 8
Subsidiary cell, 107
Sulphur, 454, 381, 382
Surirella (Turp.), 426, 357

— splendida (Ktz.), 357
Suspensor, 41, 56, 337, 338, 21, 293-296
Suture, 421

Swarm-cell, 198, 218, 239, 292, 196, 259, 263

Swarming motion, 446

Swarm-spore, 312, 401, 402, 405, 252, 332

Sykidion (Wright), 414

Symbiosis, 318

Symploca (Ktz.), 441, 444, 372, 373

— hydnoides (Ktz.), 372

— violacea (Hauck), 373
Synalissa symphorea (Nyl.), 279
Synange, 94, 122, 71, 94
Syncephalis (Van Tiegh.), 340

By.), 347
Synechococcus(Nag.), 447, 449
Synedra (Ehrb.), 426, 357
— Arcus(Ktz.), 357
Syngeneticae, 188, 237, 256, 232
Syzygites (Ehrb.), 337

TABELLARIA (Ehrb.), 426

Tangle, 244

Tannin-cell 34, 76, 92

Taonia (Ag.), 254

Tapetal cells, 20, 25, 36, 60, 80, 33

Tapete, 20, 80

Targionia (Mich.), 171

Targionieae, 171

Tayloria (Hook.), 149

Teeth of Hydneae, 393

— peristome, 135, 145, 111

sheath, 102, 105, 124, 83

Teleutospore, 6, 385, 386, 390, 391, 274, 314,

315

Terfezia (Tul.), 358
Terminal nodule (diatoms), 353
Tetmemorus (Ralfs), 268
Tetrachytrium triceps (Sorok.), 347
Tetrapedia (Reinsch), 447
Tetraphis (Hedw.), 149

— pellucida (Hedw.), 140, 114
Tetrasppra (Lk.), 219, 418, 448

— gelatinosa (Desv.), 418
Tetrasporange, 195, 217, 254, 170, 172-174, 177,

182, 183, 186, 190, 230
Tetrasppre, 6, 185, 195, 217, 254, 195, 231
Thalassiophyllum (Post.), 244
Thalloid Hepaticae, 135, 156, 160, 135, 136,

143-159

Thallophytes, 2, 3, 4, 135, 156, 184
Thallus, 132, 184, 191. 306, 430, 432, 153, 188,

199, 212, 227, 230, 307, 358

— compound, 306
Thamnidium (Lk.), 339
Theca, 134

Thecaphora hyalina (Fingerh.), 351

— Lathyri (Kuhn), 351
Thelephoreae, 391
Thorea (Bory), 211
Thrush-fungus, 38
Tilletia (Tul.), 350, 351

— caries (Tul.), 315, 299
Tilopterideae, 249,
Tilopteris (Ktz.), 249

Tmesipteris(Bernh.), 61, 63, 41

— tannensis (Bernh.), 41
Tndea (Willd.), 89, 90

— superba (Col.), 90
Tolypella(A. Br.), 182
Tolyposporium (Woron.), 351
Tolypothrix (Ktz.), 429, 437, 438, 439, 440, 441

— amphibia (Zopf), 440
Tortula(Hedw.), 149
Trabecule, 41, 52,- 147, 23, 32, 33, 112
Tracheide, 18, 76

Trama, 394, 395, 396, 397, 321
Traquairia (Carruth.), 114
Tree-ferns, 71, 75, 78. 85, 57
Tremella (Dill.), 389

— mesenterica (Retz.), 316
Tremellineae, 343, 388, 389
Tremelloid Uredineae, 386
Trentepohlia (Mart.), 185, 280, 284, 247
- Bleischii (Rabenh.), 247
Triceratium (Ehrb.), 420, 357

— Favus( Ehrb.), 357
Trichocoma (Jungh.), 319

Trichoayne, 188, 199, 219, 220, 360, 369, 370,
573, 378, 379, 385, 175, 176, 179,

Trichomanes (L.), 70, 71, 86, 87, 88, 61

— alatum (Sw.), 86

— pyxidiferum (L.), 86, 61
Trichome, 428, 359
Trichophilus (Web.), 280
Trichophore. 199, 176, 179
' Trichpsporange,' 237
Tripoli, 424

Trochopteris (Gardn.), 91
Truffle-family, 357
Truffles, 358

Tuber, 56, 112, 38, 86
- - (Mich.), 357, 358

— rufum (Pico), 301
Tuberaceae, 308, 357
Tubereae, 358
Tubular organ, 161
Tubuli of Polyporeas, 393
Tubulinae, 401

Tuburcinia (Berk.), 350, 351, 352

— Trientalis (Berk.), 352
Tulostoma (Pers.), 399

UDOTEA (Lmx.), 289

Udoteaceae, 289, 258

Ulodendron (Sternb.), 116

Ulothrix (Ktz.), 185, 277, 278, 279, 246

— implexa (Ktz.), 246

— zonata (Ktz.), 277
Ulotrichaceae, 187, 273, 277, 246
Ulva(L.), 189, 217, 304,196

Ulvacea;, 189, 190, 195, 196, 198, 217, 218, 219,

279, 418, 196-198
Umbelliferae, 327, 348, 364
Unicellular plants, 184, 281, 284, 286, 288, 427
Unilocular zoosporange, 187, 237, 212, 219, 220,

223
Uredineae, 4, 312, 315, 383, 391, 274, 314, 315

— (tremelloid), 386, 390
Uredo (Pers.), 383, 385
Uredospore, 6, 385, 386, 274, 314, 315

Urococ3c4us (Hass.), 418, 350

— insignis (Hass ), 350
Urocystis (Rabenh.), 350, 351, 352
Urospora (Aresch.), 273, 276
Usnea barbata (Fr.), 282
Ustilagineae, 4, 315, 349, 299

INDEX

473

UST

Ustilago (Pens.), 35 1

— carbo (Tul.), 35 1

— • destruens(Tul.), 351

— Hydropiperis (Schm.), 350

— longissima (Tul.), 351
Ustulina (Tul.), 373

VACCINIUM VITIS-ID*:A, 388
Vagine, 134, 135, 144, 146 163, 131
Vallecular canal, 105
Valonia (Gin.), 289, 411, 257

— macrophysa (Ktz.), 257
Valoniaceae, 289, 257
Valve, 420, 353-355
Valve-view, 421, 353, 354
Vampyrella (Cienk.), 405
Vascular bundle-sheath, 18, 76, 39

— Cryptogams, i, 2, 10, 2, 4-101
cylinder, 58, 39

Vaucheria (DC.), 186, 281, 283, 284, 248, 249

— dichotoma (Lyngb.), 249
-sessilis(Vauch.), 248

Veil, 50

Velum partiale, 393

— universale, 393, 397, 318

Venter, 16, 39, 68, 133, 143, 159, 109, 158

Ventral canal-cell, 16, 27, 40, 69, 143, 159, 45

Verbascum, 364

Vesicle, 23, 17, 44

Vessel, 76

Vibrio (Cohn), 440, 451

Vidalia (Lmx.), 194, aoy

Vine, 327

— mildew, 364
Violet-stone, 280
Vittaria (Sm.), 67, 85
Volkmannia (Sternb.), 127
Volva, 393, 318
Volvocinea;, 291, 292, 259
Volvox (L.), 4, 292, 295, 259

- glpbator (L.), 292, 259
Vorticella, 199

WATER-BEETLES, 378

Watei-net, 296

Weissia (Hedw.), 149

' Wendungszellen,' 179, 166

Whip-shaped filaments. 178, 163

ZYG

Woocl*ia(R. I'.r.), 85,08
Woodwardia (Sm.), 85, 53
— radicaus (Sm.), 78
Woronina (Cornu), 345, 347
* Woronin's hypha,' 360, 373, 385
Wrangelia (Ag.), 209
Wrangeliaceas, 209, 176, 177

XANTHIDIUM (Ehrb.), 269, 239
— cristatum(Bre'b.), 239
Xenococcus (Rostaf.), 444
Xylaria(Hill), 360,373, 385
Xylariea;, 373

YEAST, 380, 268, 313,

YeHow cells of Radiolarians, 318

ZA.MIA, 1

Zanardinia (Nardo), 239, 251, 252, 228, 229

- - collaris (Crouan), 228, 229
Zippea (Cord.), 124

Zonal view (diatoms), 421

Zonaria (Harv.), 254

Zonate (tetraspores), 195

Zoogamete, 185 (see also under Alga; and

Prot.), 196, 222, 246, 247, 252, 260, 263
Zoogioea, 433, 444, 451
Zoosphere, 252, 295, 229
Zoosporange, 220 (see also under Alga;, Fungi-

and Prot.), 201, 252-255, 258, 259, 272, 277 1

287-289, 291, 297
Zoosporangiophore, 326, 275, 287
Zoospore, 6 (see also under Alga;, Fungi, and

Prot.), 199, 201, 232, 242, 259, 277, 289, 291,

292,297

Zygnema (Ktz.), 258, 259, 264, 265, 267, 237
— pectinatum (Ag.), 237
Zygnemacea;, 187, 258, 259, 264, 236 233
Zygochytrium (Sorok.), 341
Zygodon (H. & T.), 149
Zygogoniura (Ktz.), 267
Zygomycetes, 4, 335, 293-299
Zygosperm, 218 (see also under Alg;e and

Fungi), 222, 233-238, 241, 252, 263, 293-293

* Zygosporea,' 3
Zygosporites (VVillhms.), 114

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