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THE STRUCTURE AND DEVELOPMENT
OF MOSSES AND FERNS

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The Structure and Development

Mosses and Ferns

{Archegon'iatae)

THIRD EDITION, REVISED AND ENLARGED

DOUGLAS HOUGHTON CAMPBELL, Ph.D.

Professor of Botany

IN THE

Leland Stanford Junior University

THE MACMILLAN COMPANY
London: Macmillan & Co., Ltd.

1928

hec up and electrotyped

Published. September, 1905

Reprinted July, 101.I

PREFACE TO THE SECOND EDITION

Since the first edition of the present work was pub-
lished, the number of important investigations on the struc-
ture and development of the Archegoniatse has been so
great that it has been found necessary to recast entirely
certain portions of the work, this being especially the case
with the chapters dealing with the eusporangiate Ferns.
The whole book, however, has been carefully revised, and a
good deal of new matter introduced, including tv/o special
chapters on the geological history of the Archegoniates,
and the significance of the alternation of generations.

Some of the new material incorporated in the present
work is published for the first time; but much of it is based
upon papers published by the writer since the first edition
was published. The work of other investigators has been
freely drawn upon, and acknowledgment has been made in
all cases where statements or illustrations have been bor-
rowed from other sources than the writer's own inves-
tigations.

The large number of recent books and papers on the
Archegoniates has involved an entire revision of the bibli-
ography, which has been materially augmented. It is
hoped that it will be found to be a fairly complete list of
the more recent works bearing upon the structure of the
Archegoniates.

The results of more recent investigations have necessi-
tated, in some cases, a modification of certain views ex-
pressed by the author in the earlier edition. In other
cases, however, his views have been confirmed as the result
of more complete knowledge of certain forms.

7->

■RE FACE

In view of the decidedly unsettled state of nomenclature
at the present time, it has seemed best to maintain a some-
what conservative attitude in this matter, and this will ex-
plain the retention of some familiar names, which perhaps
are not in accord with a strict law of priority.

The author is especially indebted to Professor E. C.
Jeffrey and to Dr. W. R. Shaw, for valuable preparations
which were of great assistance in the preparation of the
chapters on the Ferns. Thanks are also due one of my
students, Mr. H. B. Humphrey, for the preparation of the
drawings for figures 43, 44 and 47.

The author also would express his thanks to Professor
D. S. Johnson of Johns Hopkins University for kindly re-
vising a portion of the bibliography, and to Professor G.
J. Peirce of Stanford University for valuable assistance in
reading part of the proof.

DOUGLAS HOUGHTON CAMPBELL.

Stanford University,
April, 1905.

PREFACE TO THE THIRD EDITION

In the second edition of the ''Mosses and Ferns," the original
text was carefully revised, and a good deal of it was rewritten.
At the same time considerable new matter was added. In
preparing the present edition of the book, it has not seemed
necessary to change the body of the text, the new material being
given in the form of an appendix.

Since the publication of the last edition, as might be expected,
numerous contributions have been made to the literature of the
Morphology and Classification of the Archegoniates. Among
these contributions are several publications by the writer. These
are for the most part based upon collections of tropical Liverworts
and Ferns made by the writer, including some new and rare
species of the Indo-Malayan region.

A summary of the more important results of these studies as
well as those of other investigators is added to the text in the
form of an appendix, in which the new material is arranged
under the Chapter headings which deal with the allied topics
in the main text. In the appendix, also, certain errors of state-
ment and reference in the original text have been corrected.

The numerous additions in the literature on the subject have
necessitated a complete revision of the bibHography, which has
been very considerably enlarged.

It is hoped that with the appendix and augmented bibliog-
raphy the book will prove a satisfactory statement of our present
knowledge of the structure and development of the Archegoniate

Plants.

DOUGLAS HOUGHTON CAMPBELL.

Stanford University,
January, 1918.

CONTENTS

CHAPTER I
Introduction » » c i

CHAPTER H
MusciNiLE (Bryophyta) — Hepatic^ — Marchantiales 8

CHAPTER HI
The Jungermanniales c. .. 72

CHAPTER IV
The Anthocerotes « c . . c . . . 120

CHAPTER V
The Mosses (Musci) : Sphagnales — Andre^ales 160

CHAPTER VI
The Bryales « 18S

CHAPTER VII
The Pteridophyta — Filicine^ — Ophioglossace^ 229

CHAPTER VIII
Marattiales 27^

CHAPTER IX
FiLiciNE^ Leptosporangiat^ 305

CHAPTER X
The Homosporous Leptosporangiat^ (Filices) 346

CHAPTER XI
Leptosporangiat^ Heterospore^ ( Hydro pterides) 396

CHAPTER XII
Equisetine^ , 443

CHAPTER XIII
LYCOPODINE.E 483

CHAPTER XIV

ISOETACE^ c 536

CHAPTER XV
The Nature of the Alternation of Generations 562

CHAPTER XVI
Fossil Archegoniates 576

CHAPTER XVII
Summary and Conclusions 592

r-k ^^

CONTENTS

Appendix ^7

Bibliography ^45

Index ^^^

CHAPTER I

INTRODUCTION

Under the name Archegoniatae are included a large number
of plants which, while differing a good deal in many structural
details, still agree so closely in their essential points of
structure and development as to leave no room for doubting
their close relationship. Besides the Bryophytes and Pteri-
dophytes, which are ordinarily included under this head, the
Gymnospermse or Archespermae might very properly be also
embraced here, but we shall use the term in its more restricted
meaning.

The term Archegoniatae has been applied to these plants
because the female reproductive organ or archegonium is
closely alike, both in origin and structure, in all of them. This
is a multicellular body, commonly flask-shaped, and either
entirely free or more or less coherent with the tissues of the
plant. In all cases there is an axial row of cells developed, of
which the lowest forms the egg. The others become more or
less completely disorganized and are discharged from the
archegonium at maturity. Among the Algae there is no form
at present known in which the female organ can be certainly
compared to the archegonium, although the oogonium of the
Characeae recalls it in some respects.

The antheridium or male organ of the Archegonlatae, while
it shows a good deal of similarity in all of them, still exhibits
much more variation than does the archegonium, and is more
easily comparable w^ith the, same organ in the Algae, especially
the Characeae. Like the archegonium it may be entirely free,
or even raised on a long pedicel ; or it may be completely sunk
in the tissue of the plant, or even be formed endogenously. It
usually consists of a single outer layer of cells containing

2 MOSSES AND FERNS chap.

chlorophyll, and these enclose a mass of small colourless cells,
the sperm cells, each of which gives rise to a single ciliated
spermatozoid. The development of the latter is very uniform
throughout the Archegoniatae, and differs mainly from the
same process in the higher green Alg?e, especially the Characese,
in the larger amount of nuclear substance in the spermatozoids
of the former.

Fertilisation is only effected when the plants with ripe
sexual organs are covered with water. The absorption of
water bv the mature sexual organs causes them to open, and
then, as the spermatozoids are set free, they make their way
through the water by means of their cilia and enter the open
archegonium. into which they penetrate to the &gg. The
sexual cells do not differ essentially from those of the higher
AlgcT, and point unmistakably to the origin of the Arche-
goniatcT from similar aquatic forms. Indeed all of the
Archegoniat?e must still be considered amphibious, inasmuch
as the gametophyte or sexual plant is only functional when
partially or completely submerged.

Non-sexual gonidia are known certainly only in Ancnra,
one of the lower Liverworts, but special reproductive buds or
gemmae, both unicellular and multicellular, are common in
many forms.

A very marked characteristic of the whole group is the
sharply-marked alternation of sexual and non-sexual stages.
The sexual plant or gametophyte varies much in size and
complexity. It may be a simple flat thallus comparable in
structure to some Alg?e, and not superior to these in com-
plexity so far as the vegetative parts are concerned. In others
it becomes larger and shows a high degree of differentiation.
Thus among the Liverworts the Marchantiacere, w'hile the
gametophyte still retains a distinctly thalloid form, still show
a good deal of variety in the tissues of which the thallus is
composed. In others, e.g., the true Mosses, the gametophyte
has a distinct axis and leaves, and in the higher ones the tissues
are well differentiated for special functions. The gametophyte
itself may show two well-marked phases, the protonema and
the gametophore. The former is usually filamentous, and
arises directly from the germinating spore; and upon the
protonema, as a special branch or bud, the much more complex
gametophore is borne. Often, however, as in many thallose

I INTRODUCTION 3

Liverworts and Pteridophytes, the protonema is not clearly
distinguishable from the gametophore, or may be completely
suppressed. In the Pteridophytes the gametophyte is, as a
rule, much simpler than in the Bryophytes, resembling most
nearly the less specialised forms of the latter. In the so-called
heterosporous Pteridophytes the gametophyte becomes ex-
tremely reduced and the vegetative part almost entirely sup-
pressed, and its whole cycle of development may, in extreme
cases, be completed within twenty-four hours or even less.

The non-sexual generation, or "sporophyte," arises normally
from the fertilised tgg, but may in exceptional cases develop as
a bud from the gametophyte. In its simplest form all the
cells of the sporophyte, except a single layer upon the out-
side, give rise to spores, but in all the others there is developed
a certain amount of vegetative tissue as well, and the sporo-
phyte becomes to a limited extent self-supporting. In the
higher Bryophytes the sporophyte sometimes exceeds in size
the gametophyte, and develops an elaborate assimilative system
of tissues, abundantly supplied with chlorophyll and having an
epidermis with perfect stomata ; but even the most complex
moss-sporogonium is to a certain extent dependent upon the
gametophyte with which it remains in close connection by
means of a special absorbent organ, the foot. In these highly
developed sporogonia the sporogenous tissue occupies but a
small space, by far the greater part of the tissue being purely
vegetative.

In the Pteridophytes a great advance is made in the sporo-
phyte beyond the most complex forms found among the
Bryophytes. This advance is twofold, and consists both in an
external differentiation and a more perfect development of the
tissues. The earliest divisions of the embryo resemble very
closely those of the Bryophyte sporogonium. but at an early
stage four distinct organs are usually plainly distinguishable,
viz., stem, leaf, root, and foot.- The last corresponds in some
degree to the same organ in the moss-sporogonium, and like it
serves as an absorbent organ by which the young sporophyte
is supplied with nourishment from the gametophyte. In short,
the young sporophyte of the Pteridophyte. like that of the
Bryophyte, lives for a time parasitically upon the gametophyte.
Sooner or later, however, the sporophyte becomes entirely
independent. This is effected by the further growth of the

4 MOSSES AND FERNS chap.

primary root, which brings the young sporophyte into direct
communication with the earth. The primary leaf, or cotyle-
don, enlarges and becomes functional, and new ones arise
from the stem apex. Usually by the time this stage is reached
the gametophyte dies and all trace of it soon disappears. In
some of the lower forms, however, the gametophyte is large
and may live for many months, or even years, when not
fecundated, and even when the sporophyte is formed, the
prothallium (gametophyte) does not always die immediately,
but may remain alive for several months. The spore-forming
nature of the sporophyte does not manifest itself for a long
time, sometimes many years, so that spore-formation is much
more subordinate than in the highest Bryophytes. With few
exceptions the spores are developed from the leaves and in
special organs, sporangia. In the simplest case, c. g., Ophio-
glossuni, the sporangia are little more than cavities in the tissue
of the sporiferous leaf, and project but little above its surface.
Usually, however, the sporangia are quite free from the leaf
and attached only by a stalk. These sporangia are in the
more specialised forms of very peculiar and characteristic
structure, and are of great importance in classification.

Corresponding to the large size and development of special
organs in the sporophyte of the Pteridophytes, there is a great
advance in the specialisation of the tissues. All of the forms
of tissue found in the Spermaphytes occur also among the
Pteridophytes, which indeed, so far as the character of the
tissues of the sporophyte is concerned, come much nearer to
the former than they do to the Bryophytes. This is especially
true of the vascular bundles, which in their complete form are
met with first in the sporophyte of the Pteridophyta. In size,
too, the sporophyte far exceeds that of the highest Mosses ;
while in these the sporogonium seldom exceeds a few centime-
tres in extreme height, in some Ferns it assumes tree-like pro-
portions with a massive trunk lo to 15 metres in height, with
leaves 5 to 6 metres in length.

In the formation of the spores all of the Archegoniatse
show great uniformity, and this extends, at least as regards
the pollen spores, to the Spermatophytes as well. In all cases
the spores arise from cells which at first form a solid tissue
arising from the division of a single primary cell, or group of
cells (Archesporium). These cells later become more or less

I INTRODUCTION 5

completely separated, and each one of these so-called ^'spore
mother cells,'' by division into four daughter cells, forms the
spores. The young spores are thin walled, but later the wall
becomes thicker and shows a division into two parts, one inner
layer, which generally shows the cellulose reaction and is called
the endospore (intine), and an outer more or less cuticularised
coat, the exospore (exine). In addition a third outer coat
(perinium, epispore) is very generally present. As the spore
ripens there is developed within it reserve food materials in
the form of starch, oil, and albuminous matter, and quite
frequently chlorophyll is present in large quantity. Some
spores retain their vitality but a short time, those of most
species of Eqiiisctum and Osmunda, for example, germinating
with difficulty if kept more than a few days after they are
shed, and very soon losing their power of germination com-
pletely. On the other hand, some species of Marsilia have
spores so tenacious of life that they germinate perfectly after
being kept for several years.

From the germinating spore arises the gametophyte bear-
ing the sexual organs. Both archegonia and antheridia may
be borne upon the same plant, or they may be upon separate
ones. From the fertilised tgg within the archegonium is pro-
duced the sporophyte or non-sexual generation, and from the
spores which it produces arise the sexual individuals again,
thus completing the cycle of development.

On comparing the lower Archegoniates with the higher
ones, it is at once evident that the advance in structure consists
mainly in the very much greater development of the sporophyte.
In the Bryophytes, as a class, the gametophyte is more impor-
tant than the sporophyte, the latter being, physiologically,
merely a spore-fruit, which in many forms, e. g., Sphagnum, is
of relatively rare occurrence. The gametophyte in such forms
is perennial, and the same plant may produce a large number of
sporogonia, and at long intervals. The sporophyte in such
forms is small and simple in structure, and its main function
is spore formation, as it has but little power of independent
growth. In the Pteridophytes, on the other hand, the gameto-
phyte (prothallium) rarely produces more than one sporophyte,
and as soon as this, by the formation of a root and leaf, becomes
self-supporting, the gametophyte dies. In short, the sole

6 MOSSES AND FERNS chap.

function of the latter in most of them is to support the sporo-
phyte until it can take care of itself.

When the lower Pteridophytes are compared with the more
specialised ones, a similar difference is found. In the lower
forms, like the ]\Iarattiacere and Equisetace^e, the gametophyte
is relatively large and long-lived, and closely resembles certain
Liverworts. In these forms a considerable time elapses before
sexual organs are produced, and in artificial cultures of the
Marattiace?e a year or more sometimes passes before archegonia
are formed. These prothallia, too, multiply by budding, much
as the Liverworts do. In case no archegonia are fecundated
the prothallium may grow until it reaches a length of three or
four centimetres, and resembles in a most striking manner a
thallose Liverwort. In such large prothallia it is not unusual
for more than one archegonium to be fecundated, although
usually only one of the embryos comes to maturity, and the
prothallium may continue to live for some time after the
sporophyte has become independent. Usually, however, as
soon as an archegonium is fertilised, the formation of new ones
ceases, and as soon as the sporophyte is fairly rooted in the
ground the prothallium dies.

In most of the lower Pteridophytes the prothallia are
monoecious, but in the more specialised ones are markedly
dioecious. When this is least marked the males and females
differ mainly in size, the latter being decidedly larger; in the
more extreme cases the difference is much more pronounced
and is correlated with a great reduction in the vegetative part
of the gametophyte of both males and females. This reaches
its extreme phase in the so-called heterosporous forms. In
these the sex of the gametophyte is already indicated by the
character of the spore. Two sorts of spores are produced, large
and small, which produce respectively females and males. In
all of the heterosporic Pteridophytes the reduction of the vege-
tative part of the gametophyte is very great, especially in the
male plants. Here this may be reduced to a single quite
functionless cell, and all the rest of the plant is devoted to tlie
formation of the single antheridium. In the female plants the
reduction is not so great ; and although sometimes but one
archecronium is formed, there mav be in some cases a consider-
able number, and owing to the large amount of nutritive
material in the spore, in case an archegonium is not fertilised,

I INTRODUCTION 7

the prothallium, even if it does not form chlorophyll, may grow
for a long time at the expense of the food materials that nor-
mally are used by the developing embryo. In strong contrast
to the slow growth and late development of the reproductive
organs in the homosporous forms, most of the heterosporous
Pteridophytes germinate very quickly. The Marsiliacese, in
which the female prothallium is extremely reduced, show the
opposite extreme. Here the whole time necessary for the
germination of the spores and the maturing of the sexual
organs may be less than twenty-four hours, and within three or
four days more the embryo is completely developed.

That heterospory has arisen independently in several widely
separated groups of Pteridophytes is plain. The few genera
that still exist are readily separable into groups that have
comparatively little in common beyond possessing two sorts of
spores ; but each of these same forms shows much nearer
affinities to certain widely separated homosporous groups.

In some of the heterosporous forms the first divisions in the
germinating spore take place while it is still within the sporan-
gium, and may begin before the spore is nearly fully devel-
oped. In other cases the sporangia become detached when
ripe, and the spore (or spores), still surrounded by the spo-
rangium, falls away from the sporophyte before germination
begins. In these respects the heterosporous Pteridophytes
show the closest analogy with the similar processes among the
lower Spermatophytes, where it has been shown in the most
conclusive manner that the ovule with its enclosed embryo-sac
is the exact morphological equivalent of the macrosporangium
of SelagineUa or AzoUa, for example, and that the seed is
simply a further development of the same structure.

CHAPTER II

MUSCINAE (BRYOPHYTA)— HEPATICAE— MARCHANTIALES

The first division of the ArchegoniatcX, the Muscineae or
Bryophyta, comprises the three classes, Hepaticae or Liverworts,
the Musci or Mosses and the Anthocerotes. In these as a rule
the gametophyte is much more developed than the sporophyte,
and indeed in many forms the latter is very rarely met with.
They are plants of small size, ranging in size from about a milli-
metre in length to 30 centimetres or more. A few of them are
strictly aquatic, i. e., Riclla and Ricciocarpus among the Hepat-
ic3e, and Fontinalis of the Mosses; but most of them are
terrestrial. A favourite position for many is the trunks of
trees or rocks. Many others grow upon the earth. They
vegetate only when supplied with abundant moisture, and
some forms are very quickly killed if allowed to become dry;
but those species which grow in exposed places may be com-
pletely dried up without suffering, and some of those that
inhabit countries where there are long dry periods may remain
in this condition for months without losing their vitality,
reviving immediately and resuming growth as soon as they are
supplied with the requisite moisture.

The germinating spores usually produce a more or less
well-marked "protonema," from which the gametophore arises
secondarily. The protonema sometimes is persistent and
forms a dense conferva-like growth, but more commonly it is
transient and disappears more or less completely after the
gametophore is formed. No absolute line, however, can be
drawn between protonema and gametophore, as the former
may arise secondarily from the latter, or even from the sporo-
phyte. With very few exceptions, e.g., Biixbauiuia, the game-
tophyte of the Muscineai is abundantly supplied with chloro-

CH. II MUSCINEJB— HEPATIC^— MARCHANTIALES 9

phyll, and therefore capable of entirely independent growth.
No true roots are found, but rhizoids are generally present in
great numbers, and these serve both to fasten the plant to the
substratum and also to supply it with nutriment.

The form of the gametophyte varies much. In the simplest
Hepaticce, like Aneiira and Pcllia, it is a flat, usually dichoto-
mously branched thallus composed of nearly or quite uniform
cells, without traces of leaves or other special organs. From
this simplest type, which is quite like certain Algre, differentia-
tion seems to have proceeded in two directions; in the first
instance the plant has retained its thallose character, but there
has been a specialisation of the tissues, as we see in the higher
Marchantiace^. In the second case the differentiation has
been an external one, the thallose form giving place to a dis-
tinct leafy axis. This latter form reaches its completest
expression in the higher Mosses, where it is accompanied by a
high degree of specialisation of the tissues as well. The
growth is usually from a single apical cell, which varies a good
deal in form among the thallose Hepaticge, but in the foliose
Hepaticse and Mosses is with few exceptions a three-sided

pyramid.

The gametophyte of the Muscineae frequently is capable of
rapid multiplication, which may occur in several ways. Where
a filamentous protonema is present this branches extensively,
and large numbers of leafy axes may be produced as buds from
it. Sometimes these buds are arrested in their development
and enter a dormant condition, and only germinate after a
period of rest. Another very common method of multiplica-
tion is for the growing ends of the branches of a plant to
become isolated by the dying away of the tissues behind them,
so that each growing tip becomes the apex of a new plant.
Very common in the HepaticcX, but less so in the Mosses, is the
formation of gemmae or special reproductive buds. These are
produced in various ways, the simplest being the separation of
single cells, or small groups of cells, from the margins of the
leaves. In the case of Aneura mnltifida they are formed within
the cells and discharged in a manner that seems to be identical
with that of the zoospores of many Alg?e. Again, multicellu-
lar gemmae of peculiar form occur in several of the Hepatic?e,
e.g., Blasia, Marchantia, where they occur in special receptacles,

MOSSES AND FERNS chap.

and among the Mosses similar ones are common in Tctraphis
and some wiher genera.

The archegonia of all the MuscinecX agree closely in their
earlier stages, but differ more or less in the different groups at
maturity. In all cases the archegonium arises from a single
superficial cell, in which three vertical walls are formed that
intersect so as to form an axial cell and three peripheral ones.
From the axial cell develop the ^gg, canal cells, and cover cells
of the neck, and from the peripheral cells the wall of the venter
and the outer neck cells. In all IMuscinCcne except the Antho-
cerotes the archegonium mother cell projects above the sur-
rounding cells, but in the latter the mother cell does not project
at all, and the archegonium remains completely sunken in the
thallus. In all other forms the archegonium is nearly or quite
free, and usually provided with a short pedicel. This is espe-
cially marked in the Mosses, where the lower part of the arche-
gonium is as a rule much more massive than in the Hepaticae.

The most marked difference, however, between the arche-
gonium of the Hepaticse and Mosses is in the history of the
cover cell or uppermost of the axial row of cells of the young
archegonium. This in the former divides at an early period
into four nearly equal cells by vertical walls, the resulting cells
either remaining undivided, or undergoing one or two more
divisions ; but in the Mosses this cell functions as an apical cell,
and to its further growth and division nearly the whole growth
of the neck is due.

The antheridia, except in the Anthocerotes, also arise from
single superficial cells, and while they differ much in size and
form, are alike in regard to their general structure. The
antheridium always consists of two parts; a stalk or pedicel,
which varies much in length, and the antheridium proper, made
up of a single layer of superficial cells and a central mass of
small sperm cells. The former always contain chloroplasts,
which often become red or yellow at maturity. The sperm
cells have no chlorophyll, but contain abundant protoplasm and
a large nucleus, which latter forms the bulk of the body of the
spermatozoid found in each sperm cell of the ripe antheridium.
The spermatozoids are extremely minute filiform bodies,
thicker behind and provided with two fine cilia attached to
the forward end. Adhering to the thicker posterior end there
may usually be seen a delicate vesicle, which represents the

II MUSCINE^— HEPATIC^— MARCH ANTI ALES II

remains of the cell contents not used up in the formation of
the spermatozoid.

When the ripe sexual organs are placed in water their
outer cells absorb water rapidly and become strongly distended,
while the central cells, i.e., the canal cells of the archegonium,
and the sperm cells, whose walls have become mucilaginous,
have their walls dissolved. The swelling of the mucilage
derived from the walls of the central cells, combined with the
pressure of the strongly distended outer cells, finally results
in the bursting open of both archegonium and antheridium.
In the former, by the forcing out of the remains of the canal
cells an open channel is left down to the tgg, which has been
formed by the contracting of the contents of the lowest of the
axial cells. In the antheridium the walls of the sperm cells
are not usually completely dissolved at the time the anther-
idium opens, so that the spermatozoids are still surrounded
by a thin cell wall when they are first discharged. This soon
is completely dissolved, and the spermatozoid then swims
away. The substance discharged by the archegonium exer-
cises a strong attraction upon the spermatozoids, which are
thus directed to the open mouth of the archegonium, which
they enter. Only a single one actually enters the ^gg, wdiere
it fuses with the egg-nucleus, and thus effects fertilisation.
The tgg immediately secretes a cellulose wall about itself, and
shortly after the fusion of the nuclei is complete the first
segmentation of the young embryo takes place.

The origin of the sexual organs is from a single cell, but
the position of this cell varies much. In the thallose Hepaticse
it is a superficial cell, formed from a segment of the apical cell
either of a main axis or of a special branch. In most of the
foliose Hepatic^ and the Mosses, the apical cell of the shoot
becomes itself the mother cell of an archegonium, and of course
with this the further growth of the axis is stopped. The
antheridia in the foliose Hepatic?e are usually placed singly
in the axils of more or less modified leaves, but in most Mosses
the antheridia form a terminal group. Mixed with the sexual
organs are often found sterile hair-like organs, paraphyses,
often of very characteristic forms. In the foliose Hepaticse
and most Mosses, the archegonia are often surrounded by
specially modified leaves, and in the former there is also an
inner cup-like perichsetium formed from the tissue surrounding

12 MOSSES AND FERNS chap.

the archegonia. In the thallose HepatiCcX, both antheridia and
archegonia are generally enclosed by a sort of capsule, similar
to the perichaetium of the foliose forms formed by the growth
of the tissue of the thallus immediately surrounding them.

The Asexual Generation
(SporopJiyfc, Sporophorc, Sporogonium)

The sporophyte of the ]\Iuscine?e is usually known as the
sporogonium, and, as already stated, never becomes entirely
independent of the gametophyte. After the first divisions are
completed there is at an early period, especially in the
HepatiCcT, a separation of the spore-producing tissue or arche-
sporium, all the cells of which may produce spores, as in Riccia
and the Mosses, or a certain number form special sterile cells
which either undergo little change and serve simply as nourish-
ment for the growing spores, as in SpJiccrocarpus, or more
commonly assume the form of elongated cells, — elaters, which
assist in scattering the ripe spores.

Classification
Class I. Hepaticcc {Liverworts)

The protonema is either rudimentary or wanting, and
usually not sharply differentiated from the gametophore. The
gametophore is, with the exception of Haplomitrhim and Calo-
hryum, strongly dorsiventral, and may be either a (usually
dichotomously) branched thallus or a stem with two or three
rows of leaves. Non-sexual multiplication of the gametophyte
by the separation of ordinary branches, or by special reproduc-
tive bodies, gonidia (Aucura mnltifida) or gemmce — (many
foliose JungermanniacCcT, Blasia, Marchantia, etc.). The
sporogonium (except in Anthocerotes) remains within the
enlarged venter (calyptra) of the archegonium until the
spores are ripe. Before the spores are shed the sporogonium
generally breaks through the calyptra by the elongation of the
cells of the stalk or seta. All the cells of the archesporium
may produce spores, or part of them may produce sterile cells
or elaters.

II MUSCINE^— HEPATIC^— MARCH ANTI ALES 13

Class II. Anthocerotcs.

Gametophyte, a simple thallus, or sometimes showing a
trace of leaf- formation in Dcndroceros; a single large chloro-
plast, containing a pyrenoid, in each cell ; archegonium sunk
in the thallus, the antheridium endogenous; sporophyte large,
with long continued basal growth ; sporogenous tissue derived
from the outer tissue (amphithecium) of the embryo.

Class III. Miisci (Mosses)

The gametophyte shows a sharp separation into protonema
and gametophore. The protonema arises primarily from the
germinating spore, and may be either a flat thallus or more
commonly an extensively branching confervoid growth.
Upon this as a bud the gametophore arises. This has always
a more or less developed axis about which the leaves are
arranged in two, three, or more row^s. A bilateral arrange-
ment of the leaves is rare, and the stems branch monopodially.
The asexual multiplication is by the separation of branches
through the dying away of the older tissues, or less commonly
by special buds or gemmae. Both stem and leaves have the
tissues more highly differentiated than is the case in the
Hepaticce. The archesporium is developed as a rule later
than is the case in the Hepaticse, and within is a large central-
mass of tissue, the columella, wdiich persists until the capsule
is ripe. In most cases there is a large amount of assimilative
tissue in the outer part of the capsule, and the epidermis at its
base is provided with stomata. The growing embryo breaks
through the calyptra at an early stage, and the upper part is
in most cases carried up on top of the elongating sporogonium.
In very much the greater number of forms the top of the cap-
sule comes away as a lid (operculum).

THE HEPATIC^

The Hepaticse show many evidences of being a primitive
group of plants, and for this reason a thorough knowledge of
their structure is of especial importance in studying the origin
of the higher plants, as it seems probable that all of these
are derived from Liverwort-like forms. On comparing the

14 MOSSES AMD FERNS chap.

Hepaticse with the Mosses one is at once struck with the very
much greater diversity of structure shown by the former group,
although the number of species is several times greater in the
latter. On the one hand, the Hepatic?e approach the Alg?e,
the thallus of the simpler forms being but little more compli-
cated than that of many of the higher green Algse. On the
other hand, tliese same simpler Liverworts resemble in a most
striking manner the gametophyte of the Ferns. The same
difference is observed in the sporophyte. This in the simplest
Liverworts, c. g., Riccia, is very much like the spore-fruit of
Colcochccte, one of the confervoid green Algae; on the other
hand, the sporogonium of Anthoccros shows some most
significant structural affinities with the lower Pteridophytes.
The simplest form of the gametophyte among the Hepaticae
is found in the thallose Jungermanniaceae and Anthocerotes.
In such forms as Ancura (Fig. 38) and Anthoceros (Fig. 55)
the thallus is made up of almost perfectly uniform chlorophyll-
bearing tissue, fastened to the earth by means of simple
rhizoids. In forms a little more advanced, e. g., Metzgeria,
Pallavicinia (Fig. 38), there is a definite midrib present.
From this stage there has been a divergence in two directions.
In one series, the Marchantiaceac, there has been a specialisa-
tion of the tissues, with a retention of the thallose form of
the plant. In Riccia (Figs. 1-9) we find two clearly marked
regions, a dorsal green tissue, with numerous air-spaces, and a
ventral compact colourless tissue. In the higher Marchantia-
ceae (Fig. 16) this is carried still further, and the air-chambers
often assume a definite form, and a distinct epidermis with
characteristic pores is formed. In the Marchantiaceae also
ventral scales or leaf-like lamellae are developed, and rhizoids
of two kinds are present. Starting again from the flat, simple
thallus of Ancura there has been developed the leafy axis of the
more specialised Jungermanniaceae. Between the latter and
the strictly thallose forms are a number of interesting inter-
mediate forms, like Blasia and Fossomhronia, where the first
indication of the two dorsal rows of leaves is met with ; and in
Blasia at least the rudiments of the ventral row of small leaves
(amphigastra) usually found in the foliose forms are present.
The tissues of the Liverworts are very simple, and consist
for the most part of but slightly modified parenchyma. Occa-
sionally (Prcissia) thickened sclerenchyma-like fibres occur,

n MUSCINE^—HEPA TIC^— MARCH ANTIALES 15

but these are not common. Mucilage cells of various kinds
are common. The secreting cells may be hairs on the ventral
surface, and especially developed near the apex, where the
mucilaginous secretion serves to protect against drying up ; or
they may be isolated {Marchantia) or rows of cells {Cono-
ccphahis) within the tissue of the thallus.

The growth of the gametophyte is usually due to the
division of a single apical cell. In some of the thallose forms,
e.g., Ivlarchantiace?e, Anthocerotes, a single initial cell is not
always to be recognised in the older thallus, Imt in these forms
a single initial always appears to be present in the earlier stages.
In the Jungermanniacege, how^ever, a single apical cell is always
distinguishable, but varies a good deal in form in different
genera, at least among the thallose forms, or even in the same
genus. Among the foliose Jungermanniacese it always has
the form of a three-sided pyramid. From the apical cell seg-
ments are cut off in regular succession, and the first divisions
of the segments also show much regularity, and often bear a
definite relation to the tissues of the older parts.

The Sexual Organs

The archegonium is always traceable to a single cell, but
the position of the mother cell is very different in different
genera. In the simplest cases, e.g., Riccia, Splicer ocarpiis
(Figs. 2, 29), the mother cell is formed from a superficial cell
of one of the youngest dorsal segments of the apical cell, close
to the growling point of an ordinary branch of the thallus,
whose growth is in no way affected by the formation of arche-
gonia. In such forms the archegonia stand alone, and about
each is developed a sort of involucre by the growth of a ring
of cells immediately surrounding the archegonium rudiment.
In other cases the archegonia are found in groups, e, g., Palla-
mcinia (Fig. 38), separated by -spaces where no archegonia are
found. Here each group of archegonia has a common invol-
ucre. In Aneura and most of the higher Marchantiacese the
archegonia are found in the same way, but upon special modi-
fied branches. In the foliose Jungermanniacese the origin of
the archegonia is somewhat different. Here they are formed
upon short branches, where, after a small number of perichaetial
leaves have been formed, the subsequent segments of the apical

i6 MOSSES AND FERNS chap.

cell develop archegonia at once, and finally the apical cell itself
becomes the mother cell of the last-formed archegonium, and,
of course, with this the growth in length of the branch ceases.
With the exception of the Anthocerotes, where the arche-
gonium mother cell does not project at all, it quickly assumes
a papillate form and is divided by a transverse wall into a basal
cell, and an outer one from which the archegonium itself
develops. The divisions in this outer cell are remarkably
uniform. Three vertical walls are first formed, intersecting so
as to enclose a central cell (Fig. 2, G). In this central cell a
transverse wall next cuts off a small, upper cell (cover cell)
from a lower one. Subsequently the three (or in the
Jungermanniaceae usually but two) first-formed peripheral
cells divide again vertically, and by transverse walls in all of
the peripheral cells, and somewhat later in the central one also,
the young archegonium is divided into two tiers, a lower one
or venter, and an upper one, the neck (Fig. 2, F). The middle
cell of the axial row, by a series of transverse walls, gives
rise to the row of neck canal cells, and the lowermost cell
divides into two an upper one, the ventral canal cell, and a
larger lower one, the egg.

The antheridium shows very much greater diversity in its
structure, and equally great difference in its position. The
origin in the thallose forms is usually the same as that of the
archegonium, and indeed where the two grow mixed together,
as in many species of Riccia, it is sometimes difficult to
distinguish them in their earliest stages. Usually, however,
the antheridia are borne together, either on special branches
{MarcJiantia, species of Ancura), or they are produced in a
special part of the ordinary thallus, which usually presents a
papillate appearance (e.g., Fiinhriaria). In the foliose Junger-
manniace?e the antheridia are often borne singly in the axils
of slightly modified leaves, but in no case does the apical cell
of the shoot become transformed into an antheridium. The
antheridium, like the archegonium, arises from a single super-
ficial cell. The first division usually divides the primary cell
into a stalk cell and the body of the antheridium. The first
may remain very short and undergo but few divisions, or it
may develop into a stalk of considerable length. The first
division in the upper cell may be either transverse (Marchan-
tiaceae, Sphccrocarpus) or vertical (Jungermanniace^e).

II MUSCINEJE—HEPA TIC^— MARCH ANTI ALES 17

Later, by a series of periclinal walls, a central group of cells is
separated from an outer single layer of cells. The latter divide
only a few times, and develop chlorophyll, which sometimes
changes into a red or yellow pigment at maturity. The inner
cells give rise to a very large number of sperm cells, which in
most Hepaticse are extremely small, and consequently not well
adapted to studying the development of the spermatozoids. In
a few forms, however, they are larger ; and in Pcllia especially,
where the sperm cells are relatively large, the development has
been carefully studied by Guignard ( i ) , Buchtien ( i ) , and
others of late years, as well as by many of the earlier observers,
and a comparison with other Hepaticae shows great uniformity
in regard to the origin and development of the spermatozoid.
After the last division of the central cells the nuclei retain their
flattened form, and thus the sperm cells or spermatids remain
in pairs, an appearance very common in the ripe antheridium
of most Liverworts. Just before the differentiation of the
body of the spermatozoid begins, the nucleus has the appearance
of an ordinary resting nucleus, but no nucleolus can be
seen. The first change is an indentation in the edge of the
discoid nucleus, and this deepens rapidly until the nucleus
assumes a crescent form. One of the ends is somewhat sharper
and more slender than the other, and this constitutes the
anterior end. As the body of the spermatozoid grows in
length it becomes more and more homogeneous, the separate
chromosomes apparently fusing together as the body develops.
The body of the spermatozoid increases in length until it forms
a slender spiral band coiled in a single plane, lying parallel with
the one in its sister cell. The full-grown spermatozoid in
Pellia cpiphylla has, according to Guignard ((i), p. 67) from
three to four complete coils. Usually when the spermatozoid
escapes, it has attached to the coil a small vesicle which swells
up more or less by the absorption of water. This vesicle is
the remains of the cytoplasm of the cell, and may, perhaps,
contain also some of the central part of the nucleus. Gui-
gnard ((i), p. 66) asserts that sometimes the cytoplasm is all
used up during the growth of the spermatozoid, and that the
free spermatozoid shows no trace of a vesicle.

In the Ricciaceas and in Sphccrocarpus new archegonia
continue to form even after several have been fertilised, so that
numerous sporogonia develop upon the same branch of the

i8 MOSSES AMD FERNS chap.

thallus; but in most Liverworts the fertilisation of an arche-
gonium checks the further formation of archegonia in the same
group, and only those that are near maturity at the time reach
their full development ; and even if more than one archegonium
of a group is fecundated, as a rule but one embryo comes to
maturity.

The Sporophyte

Unquestionably the lowest type of sporogonium is found
in Riccia (Fig. 6). Here the result of the first divisions in
the embryo is a globular mass of cells, which a little later shows
a single layer of peripheral cells and a central mass of spore
mother cells, all of which produce spores in the usual way.
The sporogonium remains covered by the venter of the arche-
gonium until the spores are ripe, and never projects above the
surface of the thallus. The spores only escape after the thallus
(or at least that part of it containing the sporogonia) dies and
sets them free as it decays. In the genus Sphccrocarptis (Fig.
30), which may be taken to represent the next stage of develop-
ment, we notice two points in which it differs from Riccia. In
the first place there is a basal portion (foot), which is simply an
absorbent organ, and takes no part in the production of spores.
Secondly, only a part of the archesporium develops perfect
spores. A number of the spore mother cells remain undivided,
and serve simply to nourish the growing spores. In the
majority of the Hepaticas the sporogonium shows, besides the
foot and the capsule, an intermediate portion, the stalk or seta,
which remains short until the spores are ripe, when, by a rapid
elongation of its cells, the capsule is forced through the calyptra
and the spores are discharged outside. In these forms, too,
some of the cells of the archesporium remain undivided, and
very early are distinguished by their elongated shape from the
young spore mother cells. These elongated cells later develop
upon the inner surface of the cell wall peculiar spiral thickened
bands, which are strongly hygroscopic. These peculiar fusi-
form cells, the elaters, are found more or less developed in all
the Hepaticce except the lowest ones.

The dehiscence of the sporogonium is different in the
different orders. In the RicciacCcC and some Marchantiaceae
the ripe sporogonium opens irregularly; in a few cases (species
of Fimbriaria) the top of the capsule comes off as a lid; ir

II MUSCINE^—HEPA TIC^— MARCH ANTI ALES 19

most Jungermanniales the wall of the capsule splits vertically
into four valves.

The spores are always of the tetrahedral type, i.e., the
nucleus of the spore mother cell divides twice before there is
any division of the cytoplasm, although this division may be
indicated by ridges projecting into the cell cavity, and partially
dividing it before any nuclear division takes place. The four
nuclei are arranged at equal distances from each other near the
periphery of the mother cell, and then between them are formed
simultaneously cell w^alls dividing the globular mother cell into
four equal cells having a nearly tetrahedral form. These
tetrads of spores remain together until nearly full grown, or in
a few cases until they are quite ripe. In the ripe spore two,
sometimes three, distinct coats can be seen, the inner one
(endospore, intine) of unchanged cellulose, the outer one
(exospore, exine), strongly cutinized and usually having upon
the outside characteristic thickenings, ridges, folds, spines, etc.
Where these thickenings are formed from the outside they
constitute the third coat (perinium, epispore). The exospore
is especially well developed in spe'cies wdiere the spores are
exposed to great heat or dryness, and w^hich do not germinate
at once. In those species that are found in cooler and moister
situations, especially where the spores germinate at once, the
exospore is frequently thin. The nucleus of the ripe spore is
usually small. The cytoplasm is filled with granules, mostly
albuminous in nature, with some starch and generally a great
deal of fatty oil that renders the contents of the fresh spore
very turbid. Some forms, especially the foliose Junger-
manniaceae, have also numerous chloroplasts, but these are lack-
ing usually in those forms that require a period of rest before
germination. In Pellia and Conocephalus the first divisions in
the germinating spore take place while the spores are still
within the sporogonium.

The germination of the spores begins usually by the forma-
tion of a long tube (germ-tube, "Keimschlauch" of German
authors), into which pass the granular contents of the spore.
At the same time there may be formed a rhizoid growing in
a direction opposite to that of the germinal tube, although quite
as often the formation of the first rhizoid does not take place
until a later period. If the spore does not contain chlorophyll
before germination, it is developed at an early stage, before any

20 MOSSES AND FERNS chap.

cell-divisions occur. Often the formation of a germ-tube is
suppressed and a cell surface or cell mass is formed at once,
and all these forms may occur in the same species. The
germination only takes place when the light is of sufficient
intensity, and tlie amount of light is a very important factor
in determining the form of the young plant. Thus if the light
is deficient, the germ-tube becomes excessively long and slender,
and divisions may be entirely suppressed. An excess of light
tends to the development at once of a cell surface or cell mass.
In the simpler thallose forms the first few divisions in the
young plant establish the apical cell, and we cannot properly
speak of the gametophore as arising secondarily from a
protonema ; in other cases, however, the young plant does arise
as an outgrowth or bud from a protonema, which only rarely
has the branching filamentous character of the Moss protonema.

Classification of the Hepaticae

The Hepaticae are readily separated into the two following
well-marked orders :

Order I Marchantiales.
Order II. Jungermanniales.

The following diagnoses are taken, with some modifica-
tions from Schiffner ((i), p. 5) :

Order I. MarcJiaiitialcs.

Gametophyte always strictly thallose, composed of several
distinct layers of tissue, the uppermost or chlorophyll-bearing
cells usually containing large air-spaces. The dorsal epidermis
usually provided with pores, ventral surface with scales ar-
ranged in one or two longitudinal rows. Rhizoids of two
kinds, those with smooth walls, and papillate ones; sexual
organs, except in the lowest forms, united in groups which
are often borne on special stalked rece])tacles. The first
divisions of the embryo are arranged like the quadrants of a
sphere. Sporogonium either with or without a stalk, and all
the inner cells forming spores, or some of them producing
elaters. No columella present.

II MUSCINE/B—HEPA TIC^— MARCH ANT I ALES 21

Fam. I. Ricciacccc

Chlorophyll-bearing tissue with or without air-chambers,
and, where these are present, they never contain a special assim-
ilative tissue. Epidermal pores wanting or rudimentary.
Sexual organs immersed in open cavities upon the dorsal
surface. Sporogonium without foot or stalk, and remaining
permanently w^ithin the venter of the archegonium. All the
cells of the archesporium produce spores.

Fam. 2. CorsiniacecB.

Air-chambers well developed; epidermis with distinct
pores; sexual organs in distinct groups, but the receptacles
always sessile; sporogonium with a short stalk, producing
besides the spores sterile cells, which may have the form of
very simple elaters.

Fam. 3. MarchafitiacecB

Air-chambers usually highly developed, and the chambers
often containing a loose filamentous assimilative tissue. Pores
upon the dorsal surface always present (except in Diimortiera
and Monoclea) and highly developed, ring-shaped or cylin-
drical. Sexual organs always in groups, usually upon special
long-stalked receptacles. Sporophyte stalked and when ripe
breaking through the calyptra, opening by teeth or a circular
cleft, more seldom by four or eight valves. The archesporium
develops sterile cells, in the form of elaters, as well as spores.

The Marchantiales constitute a very natural order of
plants, all of whose members agree very closely in their funda-
mental structure. The separation of the RicciacecX as a group
co-ordinate with the Jungermanniales and Marchantiales is not
warranted, as more recent investigations, especially those of
Leitgeb ( (7), vol. iv.) have shown that the two groups of the
Marchantiacese and Ricciacese merge almost insensibly into each
other.

They are all of them strictly thallose forms, the thallus
being unusually thick and fleshy, and range in size from a few
millimetres in some of the smaller species of Riccia, to 10 to 20
centimetres in some of the larger species of Dumortiera and
Conocephahis. In most of them branching is prevailingly

MOSSES AND FERNS

CHAP.

dichotomous, and as this is rapidly repeated, it often causes the
thallus to assume an orbicular outline. Some forms, however,

Fig. I. — Marchantiales. A, B, Male plants of Finibriaria Californica, A, from above;
B, from below; (^, antheridial receptacle; /, ventral lamellae, X4; C, Riccia glauca,
X6; sp, sporogonia; D, Conocephalus conicus, X4; E, Targionia hypophylla, X2;
(^, antheridial branch.

e.g., Targionia (Fig. i, E), may fork comparatively seldom,
and the new branches are for the most part lateral. The thallus

II MUSCINE^—HEPA TIC JE— MARCH ANTI ALES 23

is fastened to the substratum by rhizoids, which are unicellular
and usually of two kinds, those with smooth walls and those
with peculiar papillate thickenings or teeth that project inward
(Fig. 12). The cells of the lower layers of tissue are usually
nearly or quite destitute of chloroplasts, which, however, occur
in large numbers in the so-called chlorophyll-bearing layer, just
below^ the dorsal epidermis. This chlorophyll-bearing layer
contains air-spaces in all forms except some species of
Diimorticra and MonocJca, and these spaces are either simple
narrow- canals, as in Riccia glaiica, or they may be large cham^
bers separated by a single layer of cells from their neighbors.
Such forms occur in most of the higher Marchantiacese.

The growth of the thallus is due to the division of a small
group of cells occupying the bottom of the heart-shaped indent-
ation in the forward part of the thallus. Sections parallel to
the surface, cutting through this group, show a row of mar-
ginal cells that appear very much alike, and it is impossible
always to tell certainly w^hether or not there is a single definite
initial cell. Such a single initial is unquestionably present in
the earlier stages, and it is quite possible that it may persist, but
owing to its small size and its close resemblance to the adjoin-
ing cells, this cannot be positively asserted. In vertical sections
the initial cell (or cells) appears nearly triangular, with the
free outer wall somewhat convex. From this cell two sets of
segments are cut off, the dorsal segments giving rise to the
green tissue, and the lower segments producing the ventral
lamellae and colourless lower layers of cells of the thallus.

The plants multiply asexually either by the older parts of
the thallus dying away and leaving the growing points isolated,
or lateral branches, which are often produced in great numbers
from the lower surface of the midrib, become detached and each
branch forms a separate plant. The well-known gemmae of
Marchantia and Lmmlaria are the most striking examples of
special asexual reproductive bodies.

The sexual organs are always derived from the dorsal
segments of the apical cell, either of the ordinary branches or
of special shoots. The archegonium is of the typical form, and
the antheridium always show-s a series of transverse divisions
before any longitudinal walls are formed in it.

While the gametophyte may reach a very considerable
degree of specialisation, the sporophyte is relatively insignifi-

24 MOSSES AND FERNS chap.

cant even in the higher forms, and has the foot and stalk poorly
developed. While the Marchantiales grow for the most part
in moist situations, and some of them, e.g., Marchantia poly-
morpha, are very quickly killed by drying, some species, e.g.,
Riccia frieJioearpa, a common California species, grow by pref-
erence in exposed rocky places exposed to the full force of the
sun. This latter species as well as several others of the same
region, e.g., F'unhriaria Californica, Targionia JiypopJiylla, do
not die at the end of the rainy season, but become completely
dried up, in which condition they remain dormant until the
autumn rains l^egin, when they absorb water and begin to grow
again at once. In these cases usually only the ends of the
branches remain alive, so that each growing tip becomes the
beginning of a new plant.

The Ricciace^

As a type of the simplest of the Marchantiace?e, we may
take the genus Riccia, represented, according to Schiffner
((i), p. 14), by 107 species, distrilmted over the whole earth.
Most of them are small terrestrial plants forming rosettes upon
clay soil or sometimes in drier and more exposed places. A
few species, e.g., R. fluitans, are in their sterile condition sub-
mersed aquatics, but only fruit when by the evai)oration of the
water they come in contact with the mud at the JDOttom.

The dichotomously branched thallus shows a thickened
midrib, which is traversed upon the dorsal surface by a longi-
tudinal furrow which in front becomes very deep. At the
bottom of this furrow, at the apex of the thallus, lies the grow-
ing point. A vertical section through this shows a nearly
triangular apical cell which lies much nearer the ventral than
the dorsal surface (Fig. 2, ,r). From this are cut off succes-
sively dorsal and ventral segments. Each segment next
divides into an inner and an outer cell. From the outer cells
of the dorsal segments the sexual organs arise, and from those
of the ventral segments the overlapping lamella? upon the lower
surface of the thallus, and also the rhizoids. The rapid
division of the inner cells of the segments, especially those of
the dorsal ones, causes the thallus to become rapidly thicker
back of the apex. Sections made parallel to the surface of the
thallus, and passing through the growing point (Fig. 3), show

MUSCINE^—HEPA TIC^—MARCHANTJALES

that the margin is occupied by a group of cells that look very
much alike. Sometimes one of these cells is somewhat larger
than the others, but more commonly it is impossible to decide
with certainty that a single initial is present. From a com-
parison of the two sections it is at once evident that the initial
cells have nearly the form of the segment of a disc, and that in
addition to the dorsal and ventral segments lateral ones are cut
off as well. In the region just back of the apex the tissue of

Fig. 2. — Riccia glauca. Development of the archegonium, XS25- A, Vertical section
through the growing point; x, apical cell; ar, young archegonium; //, ventral
lamellae; B-F, successive stages in the development of the archegonium, seen in
longitudinal section; G, cross-section of young archegonium (diagrammatic).

the thallus is compact, but in the older parts a modification is
observable both on the dorsal and ventral surfaces. In the
former, a short distance from the growing point, the superficial
cells project in a papillate mariner above the surface. This
causes little depressions or pits to be formed betw^een the adja-
cent cells (Fig. 3, C). The subsequent divisions in the papillre
are all transverse, and this transforms each papillate surface cell
into a row of cells w^hich, as it elongates, causes the pits
between it and the adjacent ones to become deep but narrow
air-channels, so that in the older parts of the thallus the upper
portion is composed of closely-set vertical rows of chlorophyll-
bearing cells separated by narrow clefts opening at the surface.

MOSSES AND FERNS

CHAP.

In Riccia glauco, as well as other species, the uppermost cell of
each row often enlarges very much, and with its fellows in the
other rows constitutes the epidermis. According to Leitgeb's
researches this epidermal cell is formed by the first division in
the outer cell of the segment, and either undergoes no further
division, or by dividing once by a transverse wall forms a two-
layered epidermis ( R. BischofFii). On the ventral side the
outer cells of the segments project in much the same way, 1>*«

Fig. 3. — Riccia glauca. Horizontal sections of the growing point. A, B, XS25; C,
X about 260. C shows the dichotomy of the growing point; x, x', the two new
growing points; L, the lobe between them; ar, a young archegonium.

they remain in close contact laterally with the neighboring cells,
so that instead of forming isolated rows of cells, transverse
plates or lamelLx, occupying the median part of the lower sur-
face of the thallus, are formed. These remain but one cell
thick, and grow very rapidly, and bend up so as to completely
protect the growing point. With the rapid widening of the
thallus in the older parts these scales are torn asunder, and the
two halves being forced apart constitute the tw^o rows of ventral
scales found in the older parts. Later these scales dry up and

n MUSCINE^—HEPA TIC^— MARCH ANTI ALES 27

are often scarcely to be detected except close to the growin
point.

In the case of Ricciocarpus natans (Leitgeb (7), iv., p. 29)
instead of a single scale being formed, each cell of the horizon-
tal row, which ordinarily gives rise to a single scale, grows
out independently, much as do the dorsal surface cells in the
other species, and the result is a horizontal series of narrow
scales, each one corresponding to a single cell of the original
row. These later are displaced by the subsequent growth of
the thallus, and their arrangement in transverse series can only
be seen in the younger parts. The very rapid increase in length
of the dorsal rows of cells as they recede from the growing
point soon causes them to overarch the latter, which thus comes
to lie in a deep groove ; indeed not infrequently the end cells of
the rows on opposite sides of the groove actually meet, so that
the groove becomes a closed tube.

R. iiuitans (Leitgeb (7), iv. p. 11) and R. crystallina differ
in some respects from the other forms. In these, owing to a
greater expansion of the tissues of the older parts of the thallus,
the air-spaces are very much enlarged. In the former they are
almost completely closed above, as the epidermal cells, by
repeated vertical divisions, keep pace with the growth of the
thallus and form a continuous epidermis, with only a small
central pore over each of the large air-chambers. In R. crys-
tallina, however, there is no such secondary growth of the
epidermal cells, and in consequence the cavities are completely
open above, so that the surface of the thallus presents a series
of wide depressions separated by thin lamellae. These two
species also show some difference as to the ventral scales.
Those of R. Uiiitans are small and do not become separated into
two, and in R. crystallina they are wanting entirely.

Most of the Ricciaceae multiply by special adventive shoots
that arise from the ventral surface of the midrib. These
become detached and form new individuals. According to
Fellner ( i ) the rhizoids develop at the apex a young plant in a
manner entirely similar to that by which the young plant arises
from the germ tube of the germinating spore.

By far the commonest method of branching in most species
of Riccia is a true dichotomy. The first indication of this
process is a widening of the growing point and a correspond-

28 MOSSES AND FERNS chap.

ing increase in the number of the marginal cells. The central
cells of the marginal group now begin to grow more vigorously
than the others and to project as a sort of lobe (Fig. 3, C, L),
and this lobe divides the initial cells into two groups lying
on either side of it. As soon as this is accomplished each
new group of initial cells continues to grow in the same manner
as the original group, and two new growing points are estab-
lished, each of which develops a separate branch. The growth
of the middle lobe is limited, and it remains sunk in the fork
between the two new branches.

The thallus is attached to the substratum by rhizoids of
two kinds. The first are smooth-walled elongated cells, with
colourless contents, the others much like those of the higher
Marchantiacere. Their walls are undulating, and projecting
inward are numerous more or less developed spike-like protu-
berances. The rhizoids arise from large superficial cells of
the ventral part of the midrib. They are readily distinguished
from the adjacent cells by their much denser contents, even
before they have begun to project.

The arrangement of the tissues of the fully-developed
thallus is best seen in vertical cross-sections. In R. glaiica and
allied forms four well-marked tissue zones can be readily
recognized in such a section. The lowest consists of a few
layers of colourless rather loose parenchyma, from which the
rhizoids arise, and to which the ventral lamellae are attached.
Above this a more compact, but not very clearly limited region,"
the midrib. The elongated form of the midrib cells, which
contain abundant starch but no chlorophyll, is, of course, not
evident in cross-section. Radiating from the midrib are
closely-set rows of chlorophyll-bearing cells with the charac-
teristic narrow air-spaces between. The median furrow is very
conspicuous in such a section, and extends for about half the
depth of the thallus. Terminating each row of green cells is
the enlarged colourless epidermal cells, often extended into a
beak-like appendage. In some species, e.g., R. fricJwcarpa,
some of the surface cells grow out into stout thick-walled
pointed hairs.

The Sexual Organs

In Riccia the sexual organs are formed in acropetal suc-
cession from the younger segments of the initial cells, and

II MUSCINEJE—HEPA TICJE— MARCH ANTI ALES 29

continue to form for a long time, so that all stages may be met
with upon the same thallus. While both antheridia and arche-
gonia may be found together, in the two species R. glauca and
R. trichocarpa, mainly studied by myself, I found that as a rule
several of one sort or the other would be formed in succession,
and that not infrequently antheridia were quite wanting upon
plants that had borne numerous archegonia. Both archegonia
and antheridia arise from single superficial cells of the younger
dorsal segments of the initial cells. In their earliest stages
they are much alike, the mother cell of the antheridium being,
however, usually somewhat larger than that of the arche-
gonium. The cell enlarges and projects as a papilla above the
surface, when it is divided by a transverse wall into an outer
cell and an inner one. The latter divides but a few times and
forms the short stalk ; the outer cell, which has dense granular
contents, develops into the archegonium or antheridium as the
case may be. In the former case the divisions follow the
order already indicated for the typical Liverwort archegonium.
In the outer cell, which continues to enlarge rapidly, a nearly
vertical wall is formed (Fig. 2, C), which divides the cell into
two very unequal parts. This wall is curved and strikes the
periphery of the mother cell at about opposite points (Fig. 2,
G, i). A second wall of similar form is next formed in the
larger cell (G, 2), one end of which intersects the first wall,
and finally a third wall (3) intersecting both of the others is
formed. The young archegonium seen in vertical section at
this stage (Fig. 2, D) shows a large central cell bounded by
two smaller lateral ones; in cross-section the central one
appears triangular. Each of the four cells of which the arche-
gonium rudiment is now composed divides into two. The
outer ones each divide by radial walls into equal parts, and the
central one divides into an upper smaller cell (cover cell) and
a lower larger one (Fig. 3, E).-^ The next divisions are hori-
zontal and divide the young archegonium into two tiers of cells.
The lower one forms the venter, and the upper one the neck,
and next the cover cell divides into four nearly equal cells by
intersecting vertical walls. The archegonium at this stage
(Fig. 2, F) is somewhat pear-shaped, being smaller at the
bottom than at the top, and the basal cell is still undivided.
It now rapidly increases in length by the transverse division
and growth of all its cells, and there is at the same time a

MOSSES AND FERNS

CHAP.

marked increase in diameter in the venter, which finally becomes
almost globular (Fig. 4). The axial cell of the neck, the neck
canal cell, divides, according to Janczewski (i), always into
four in R. Bischoffii, and the same seems to be true for R. tricJio-
carpa (Fig. 4, A), and probably is the same in other species.
The number of divisions in the outer neck cells is various, but
is most active in the lower part, but in the central cell of the
venter there is always but a single transverse division which

Fig. 4. — A, Archegonium of Riccia trichocarpa, showing the ventral canal cell (f),
XS2s; B, ripe archegonium of R. glauca, longitudinal section, X260.

separates the ventral canal cell from the Qgg. The four
primary cover cells enlarge a good deal as the archegonium
approaches maturity, and divide by radial walls usually once,
so that the complete number is normally eight — Janczewski
gives ten in R. BiscJwifii. The basal cell finally divides into a
single lower cell whicli remains undivided, completely sunk in
the thallus, and an upper cell which divides into a single layer
of cells forming part of the venter, and continuous with the
other peripheral cells. The mature archegonium (Fig. 4)

n MUSCINE^— HEPATIC^— MARCH ANTI ALES 31

has the form of a long-necked flask with a much enlarged base.
The canal cells are completely indistinguishable, their walls
having become absorbed and the contents run together into a
granular mass. The nuclei of the neck-canal cells are small
and not readily recognisable after the breaking down of the
cell walls, but from analogy with the higher forms it is not
likely that they completely disappear in the ripe archegonium.
The cytoplasm of the central cell contracts to form the naked
globular ^gg. The cytoplasm is filled with granules, and the
nucleus, which is of moderate size, shows a distinct nucleolus,
but very little chromatin. A special receptive spot was not
certainly to be seen.

Almost coincident with the first cell division in the arche-
gonium rudiment there is a rapid growth of the cells imme-
diately surrounding it. These grow up as a sort of ring or
ridge about the archegonium, which is thus gradually immersed
in a cup-shaped cavity, and the growth of the cells about this
keeps pace with the increase in length of the archegonium, so
that even when fully grown only the very extremity of the
neck projects above the level of the thallus. The whole process
is undoubtedly but a modification of the ordinary growth of
the dorsal part of the thallus, and the space about the arche-
gonium is the direct equivalent of the ordinary air-spaces.

The first division in the primary antheridial cell is the
same as in the archegonium, but the later divisions differ much
and do not show such absolute uniformity. The first division
wall in the upper cell (Fig. 5, B) is always transverse, and
this is followed by a second similar wall, but the subsequent
divisions show considerable variation even in the same species.
After a varying number of transverse walls have been formed,
in most cases the next divisions, which are formed only in the
middle segments, are vertical, "^and divide the segments into
quadrants of a circle when seen in transverse section. Occa-
sionally a case is met with where the division walls are inclined
alternately right and left, and the divisions strongly recall
those of the typical Moss antheridium (Fig. 5, D).

The separation of the sperm cells is brought about by a
series of periclinal walls in a number of the middle segments,
by which four central cells in each segment (Fig. 5, Ti) are
separated from as many peripheral cells. These central cells

MOSSES AND FERNS

CHAP.

have, as usual in such cases, decidedly denser contents than the
peripheral ones.

The lower one or two segments and the terminal ones do
not take part in the formation of sperm cells, but simply form

Fig. s. — A-F, Development of the antheridium of R. glauca, seen in longitudinal
section; G, cross-section of a young antheridium of the same; H, antheridium of
R. trichocarpa; I, sperm cells of R. glauca. Figs. E, F, Xiso; I, X6oo, the
others X300.

part of the wall of the antheridium. The central cells now
divide with great rapidity, the division walls being formed
nearly at right angles to each other, so that the central part of
the antheridium becomes filled with a very large number of
nearly cubical cells. The divisions are formed with such
regularity that the boundaries of the original central cells
remain very clearly marked until the antheridium is nearly
mature. The basal cell of the antheridium rudiment in R.
glauca divides once by a horizontal wall (Fig. 5, B, D) and
forms the short stalk of the antheridium, which, however, is
almost completely sunk in the thallus. Between this stalk
and the central group of cells there are usually two layers of
cells, so that the wall of the antheridium is double at the base,
while it has but a single layer of cells in the other parts. The

n MUSCINE^—HEPA TIC^— MARCH ANTI ALES 33

Uppermost cells are often, although not always, extended into
a beak. The spermatozoids do not seem to differ either in
their method of development or structure from those of other
Hepaticae, but their excessively small size makes it extremely
difficult to follow through the details of their development.
When ripe the w^all cells are much compressed, but are always
to be distinguished.

Like the archegonia, the antheridia are sunk separately in
deep cavities, which are formed in exactly the same way.
Unlike the archegonia, however, the antheridium does not
nearly reach to the top of the cavity, wdiose upper walls are in
many species very much extended into a tubular neck, which
projects above the general level of the thallus, and through
which the spermatozoids are discharged.

The Sporophyte.

After fertilisation is effected the ^gg develops at once a
cell-membrane and enlarges until it completely fills the cavity
of the venter. The first division w^all is more or less inclined
to the axis of the archegonium, but approaches usually the
horizontal. The lower of the tw^o cells thus formed divides
first by a wall at right angles to the first formed, but this is
followed in the upper half of the embryo by a similar division,
so that the embryo is divided into nearly equal quadrants. In
each of the quadrants a wall meeting both of the others at
right angles next appears (Fig. 6, C, III), and the embryo at
this stage consists of eight nearly equal cells. The next walls
are not exactly alike, but the commonest form is a curved w^all
(Fig. 6, C) , striking two of the others, usually walls II and III,
and intersecting the surface of the embryo. This wall divides
the octants into two cells, wdiich appear respectively triangular
and quadrilateral in section. By the next division the arche-
sporium is separated from, the wall of the sporogonium. These
walls are periclinal, and by them a single layer of outer cells is
separated from the central mass of cells which constitutes the
archesporium (Fig. 6, B, D).

At first the cells of the embryo are much alike, but as it
grows the inner cells increase in size and their contents become
densely granular, while the outer cells grow only in breadth,
and not at all in depth, assuming more and more a tabular

MOSSES AND FERNS

CHAP.

form, and for the most part undergo divisions only in a radial
direction so that the walls remain but one cell thick in most
places. As the sporogonium increases in diameter the central
cells begin to separate and round off. llieir walls become
partially mucilaginous, and in microtome sections stain
strongly with Bismarck-brown or other reagents that stain
mucilaginous membranes. With this disintegration of the
division w^alls the cells separate more and more until they lie
free within the cavity of the sporogonium. Each of these
spore mother cells is a large globular cell with thin membrane

Fig. 6. — A, B, Young embryos of R. glaiica in longitudinal section, showing the
venter of the archegonium, X260; C, transverse section of a similar embryo,
X260; D, longitudinal section of the archegonium and enclosed embryo of R.
trichocarpa at a later stage, X220; m, the sterile cells of the sporogonium.

and densely granular contents. The nucleus is not so large as
is usually the case in cells of similar character, and, except the
nucleolus, stains but slightly with the ordinary nuclear stains.
In the fresh state these spore mother cells are absolutely opaque,
owing to the great amount of granular matter, largely drops of
oil, that they contain. In embedding these in paraffine,
however, the oil is dissolved and removed, and microtome
sections show the fine granules of the cytoplasm arranged in a
net-like pattern, the spaces between probably being occupied
by oil in the living cells.

MUSCINE^— HEPATIC^— MARCH ANTI ALES

Fig. 7, A shows the nucleus of the mother cell under-
going the first division. The small size of the nuclei, and the
small amount of chromation in them, make the study of the
details of the nuclear division difficult here, and as there was
nothing to indicate any special peculiarities these were not
followed out. After the first nuclear division the daughter
nuclei divide again, after which the four nuclei arrange them-

Fig. 7. — Riccia trichocarpa. A, Section ot a spore mother cell undergoing its first
division, X600; B, section of young spore tetrad, X300; C, section of ripe spore,
X300; D, surface view of the exospore of a similar stage, Xsoo-

selves at equal distances from each other, the division walls
form simultaneously between them, dividing the spore mother
cell into the four tetrahedral spores! A section through such
a young spore-tetrad is shown in Fig. 7, B, wdiere one of the
cells is somewhat shrunken in the processof embedding. The
cell walls at this stage are very delicate and of unchanged
cellulose ; but as they grow older the wall soon shows a separa-
tion into endospore and exospore. The latter in R. tricho-
carpa, which was especially studied, is very thick, at first
yellowish in colour, but deepening until when ripe it is black.
Sections parallel to the surface show in this species what
appear to be regular rounded pits, but vertical sections of the
spore-coat show that this appearance is due to a peculiar fold-

36 MOSSES AND FERNS chap.

ing of the exospore, which also shows a distinct striation, the
outer layer being much thicker and denser than the inner ones.
The nucleus of the ripe spore is remarkably small, and it is
evident that the dense contents of the ripe spore are largely oil
or some similar soluble substance, as in microtome sections
there is very little granular matter visible.

At the same time that the first division wall forms in the
embryo, the outer cells of the venter begin to divide by
periclinal walls, so that the single layer of cells in the wall of
the unfertilised archegonium becomes changed into two, and
the basal portion becomes still thicker; the neck takes no part
in this later growth. The cells of the venter develop a great
deal of chlorophyll, which is quite absent from the sporogonium
itself, and before the spores are ripe the inner layer of cells of
the calyptra (venter) becomes almost entirely absorbed, so that
only traces of these cells are visible when the spores are ripe.
The wall of the sporogonium also disappears almost completely
as the latter matures, but usually in microtome sections traces
of this can be made out in the ripe capsule, although the cells
are very much compressed and partially disorganised. The
contents of these cells, as well as the inner calyptra cells, no
doubt are used up to supply the growing spores with nourish-
ment. Thus, when ripe, the spores practically lie free in the
cavity surrounded only by the outer layer of calyptra cells.
The neck of the archegonium persists and is made conspicuous
by the dark brown colour of the inner walls of the cells.

Hitherto the germination of the Ricciace?e was only known
in R. glauca (Fellner (i) ). The account here given is based
upon observations made upon R. trichocarpa — a very common
Californian species. It fruits in winter and early spring, and
the spores remain dormant during the dry summer months.
If the spores are sown in the autumn they germinate within a
few days by bursting the massive black exospore, through
which the colourless endospore enclosing the spore contents
projects in the form of a blunt papilla. This rapidly grows
out into a long club-shaped filament (Fig. 8, A), much less in
diameter than the spore, and into this the spore contents pass.
These now contain albuminous granules and great numbers of
oil-globules, and some chlorophyll bodies, which at first are
small and not very numerous. They, however, increase rapidly
in size, and divide also, so that before the first cell division

MUSCINEA^— HEPATIC JE—MARCHANTI ALES

takes place the chloroplasts are abundant and conspicuous.
The formation of the first rhizoid does not take place usually
until a number of divisions have been formed in the young
thallus. The first rhizoid (Fig. 9, r) arises at the base of the
germinal tube, and is almost free from granular contents. It,
usually at least, is separated by a septum from the germ-tube.
The first wall in the latter is usually transverse, although in
exceptional cases it is oblique (Fig 8, C), and this is followed
by a second one parallel to the first (Fig. 8, C). In each of
these cells a vertical wall is formed, and then a second at right
angles to this, so that the nearly globular mass of cells at the

Fig. 8. — Riccia trichocarpa. Germination of the spores, X 190. In E the figure at
the left represents a surface view, the one at the right an optical section; K,
germinal tube.

end of the germ-tube is composed of eight nearly equal cells or
octants. As these divisions proceed the oil drops which are so
abundant in the undivided germ-tube disappear almost com-
pletely, and are doubtless used up by the growing cells.

According to Leitgeb's view, and that of other authors, the
eight-celled body at the end of the germ-tube is a sort of pro-
tonema, from which the gametophore arises as a lateral out-
growth. I have seen nothing in the species under consideration
which supports such a view. Here the axis of growth is con-
tinuous with that of the germ-tube, and in some cases at least,

MOSSES AND FERNS

CHAP.

and probably always, a single apical cell is developed at the
apex at a very early stage. Probably this initial ^ell is one of
the four terminal octant cells resulting from the first divisions.
This cell sometimes has but two sets of segments cut off from
it at first, alternately right and left, but whether this form is
constant in the young plant I cannot now say.

Fig. 9. — Riccia trichocarpa. Later stages of germination. A, from below, X260;
B, optical section of A, showing apical cell x, X520; C, X85; r, rhizoids. inter-
cellular spaces have begun to develop.

The four lower quadrants also divide, at first only by
transverse walls, and these cells lengthening give rise to a
cylindrical body composed of four rows of cells, terminated by
the more actively dividing group of cells at the summit. The
single apical cell is soon replaced by the group of initials found
in the full-grown gametophyte, and the method of growth from

ji MUSCINEAi—HEPA TIC^— MARCH ANTI ALES 39

now on is essentially the same. The growth of the cells in the
forward part of the dorsal surface of the young thallus is more
active than that of the ventral side, so that they project over
the growing point (Fig. 9), and as the outer cells of the lateral
segments of the apical cell (or cells) also increase rapidly in
size as they recede from the growing point, the forward margin
of the thallus, seen from below, is deeply indented, and the
forward part of the thallus is thus occupied by a deep cavity, at
the bottom of which, toward the ventral side, lies the growing
point. This cavity is the beginning of the groove or furrow
found in the older thallus.

At first the cells of the young thallus are without inter-
cellular spaces, but at an early period (Fig. 9, C) the outer cells
of the young segments separate and form the beginnings of the
characteristic air-spaces. In R. trichocarpa some of the dorsal
cells about the same time form short pointed papillae, the first
indication of the pointed hairs characteristic of this species.
As the plant grows, new rhizoids are formed by the growing
out of ventral cells into papillae, which are cut off by a partition
from the mother cell. These first-formed rhizoids are always
smooth-walled, and it is only at a much later stage that the
other form develops, as well as the ventral lamellae, which are
quite absent from the young plant.

Classification of the Ricciace^

Besides the genus Riccia, which includes all but three species
of the family, there are two other genera, each represented by
a single species, which undoubtedly belong here. Of these
Ricciocarpiis nafans is of almost world-wide distribution. It
is a floating form, like Riccia Huitans. Leitgeb ( (7), vol. iv.)
has made a very careful study of the structure and development
of the thallus, which differs a good deal from that of Riccia, in
which genus this plant was formerly placed. The apical
growth is essentially the same, and the differentiation of the
tissues begins in the same way, but the chlorophyll-bearing
tissue is extraordinarily developed. The air-spaces are formed
in the same way as in Riccia, but they become very deep, and
at an early stage, while still very narrow, are divided by cel-
lular diaphragms into several overlying chambers, which, nar-
row at first, later become very wide, so that the dorsal part of

MOSSES AND FERNS

CHAP.

the thallus is composed of a series of large polyhedral air-
chaml>ers arranged in several layers, and separated by walls
but one cell thick. The upper chambers communicate with
the outside by pores, quite like those of the Marchantiacese.
The ventral tissue and midrib are rudimentary, and the very
long pendent ventral lamellae are produced separately in trans-
verse rows, which, however, become displaced by the later
growth of the thallus, so that their original arrangement can
no longer be made out. Oil lx)dies like those found in the
Marchantiacese occur. The terrestrial form, which grows on
the margins of ponds, etc., where the floating form is found,
is much more richly branched and more vigorous than the
floating form (Fig. lo). The ventral scales become shorter,

and numerous wide but unthick-
r^^^ B ened rhizoids are formed, which

are almost completely lacking in
the floating form. The structure
of the reproductive organs and
sporogonium are essentially the
same as in Riccia.

Garber ( i ) , who has recently
studied the development of Riccio-
carpus, finds that it is not dioecious,
as has been frequently asserted.

Fig. .o.-Ricciocarpus natans. A, ^ut rather protcraudrous— that is,
Floating form; B, terrestrial numcrous authcridia are formed,

°^"^' ^^' but some time before the first arch-

egonia develop. Occasionally no archegonia are formed.

While the settling of the plant upon the mud is not a neces-
sary condition for Ihe development of the reproductive organs,
as has been asserted by Leitgeb, still none are formed as a rule
upon plants growing in permanent ponds, while those growing
in temporary ponds regularly develop abundant reproductive
organs. In permanent bodies of water, vegetative multipli-
cation may be very rapid, and it has been found that after these
are frozen over, a certain numl)er of the plants survive, some-
times sinking to the bottom, and resuming growth again in
the spring.

The third genus, TcsscUna (Oxyniitra), represented by the
single species, T. pyrainidata, is much less widely distributed,
belonging mainly to Southern Europe, but also found in Para-

n MUSCINE^—HEPA TIC JE— MARCH AN TI ALES 41

guay. This interesting form has also been carefully examined
by Leitgeb ((7), iv., p. 34), who calls attention to its inter-
mediate position between the RicciacCce and the Marchantiacese.
The thallus has all the characters of the latter : air-chambers
opening by regular pores, usually surrounded by six guard-
cells; two rows of ventral scales, independent from the begin-
ning; and the sexual organs united into groups upon special
parts of the thallus. The sporogonium, however, is entirely
like that of Riccia, so that it may properly be placed in the same
family. The plants are dioecious and strictly terrestrial.

A third genus, Cronisia, represented also by a single species,
C. paradoxa, is placed provisionally with the RicciacCcC by
Schiffner ((i), p. 15), but the structure and development have
not been investigated with sufficient completeness to make this
certain. It has been found only in Brazil. Schiffner says of
this form : 'Tt belongs perhaps to the Corsinie?e, and forms
a direct transition from the Ricciaceae to that family."

The C0RSINIACE.E {Schiffner (i), p. 26),

The family Corsiniacese comprises but two genera, Corsinia
and Ftmiciilaria (Boschia). Each genus contains but a single
known species. Structurally they are intermediate in character
between the Ricciace?e and Marchantiacese. Corsinia differs
from all the higher Marchantiacese in the character of the ven-
tral scales, which are formed in more than two rows, like those
of Ricciocarpns. Boschia, the other genus, has two rows of
scales of the ordinary form. The archegonia are borne in a
group in a depression upon the dorsal surface of the thallus, but
are not formed upon a special receptacle, although after fertili-
sation the cells at the bottom of the cavity multiply actively and
form a small prominence upon which the young sporogonia are
raised, and this may perhaps be the first indication of the arche-
gonial receptacle in the other forms.

The sporophyte resembles that of the Marchantiacese, but
the sterile cells in Corsinia do not develop into true elaters, and
in both genera the foot is less developed than in the true Mar-

chantiaceae.

March ANTiACE^.

Comparing the Marchantiaceae with the Ricciaceae, the close
similarity in the structure and development of the thallus is at

MOSSES AND FERNS chap.

once apparent, but the former are more highly developed in all
respects. The development of definite air-chambers in the
green tissue, and a continuous epidermis with the characteristic
pores, is common to all of them with the exception of the
peculiar genera Dumorticra and Monoclca, where the develop-
ment of the air-chambers is partially or completely suppressed.
The genera Ricciocarpus and Tcssaliua on the one hand, and
Corsinia and BoscJiia on the other, connect perfectly Riccia
with the Marchantiacere as regards the structure of air-spaces
and epidermis, as they do in other respects. The epidermal
pores in the Marchantiaceae are sometimes simple pores sur-
rounded by more or less symmetrically arranged guard cells
(Fig. 1 1, D), or they are, especially upon the female receptacles,
of a most peculiar cylindrical form, which arises by a series of
transverse walls in the primary guard cells (Fig. ii, C).
There is a good deal of difference in the character of the air-
chambers in different genera. In RchouUa and Fimhriaria,
for instance, they reseml:)le a good deal those of Ricciocarpus,
a. more or less complete division of the primary chambers being
produced by the formation of diaphragms or laminae, which
give the green tissue an irregular honey-combed appearance,
and in these forms there is not a sharp separation of the
green tissue from the ventral colourless tissue. In other
genera, Marchantia, Targionia (Fig. ,i8), Conoccphalus, the
dorsal part of the thallus is occupied by a single layer of very
definite air-chambers, each opening at the surface by a single
central pore. Seen from the surface the boundaries of these
spaces form a definite network which in Conoccphalus (Fig. i,
D) is especially conspicuous. The bottom of these chambers is
sharply defined by the colourless cells that lie below, and the
space within the chamber is filled by a mass of short, branching,
conferva-like filaments, which in the centre of the chamber have
free terminal cells, but toward the sides are attached to the
epidermal cells and are more or less confluent with the adjacent
filaments.

As in Riccia rhizoids of two kinds are present, but the
thickenings to the tuberculate rhizoids (Fig. 12) are much
more pronounced, and these are not infrequently branched, and
may extend nearly across the cavity of the hair. The ventral
scales are not produced by the splitting of a single lamella, as
in Riccia, but are separate from the first and usually arranged

II MUSCINE^—HEPA TIC^— MARCH ANTI ALES 43

in two rows. Leitgeb ((7), iv., p. 17), recognises two types
of these organs. In their earhest stages they are ahke, and
both arise from papilke close to the growing point. In both
cases this papiha is cut off from a basal cell, but in the first
type {Smitcria, Targionia, Dnmortiera) it remains terminal,
usually forming the tip of a leaf-like terminal appendage of
the scale. In the second type, represented by most of the
other genera, this originally terminal papilla is forced to one
side by the development of a lateral appendage to the scale,
which, arising at first from a single cell, rapidly increases in

rmm>

Fig. II. — Fimbriaria Californica. Development of the pores upon the archegonial
receptacle, X260. A, B, C, in longitudinal section; D, view from above.

size, and forms the overlapping dark purple marginal part of
the scale so conspicuous in many species.

In different parts of the thallus are found large mucilage
cells, which are usually isolated ; or in Conocephahis, according
to Goebel's (i) investigations, and those of Cavers (6), they
may form rows of cells which become confluent so as to form
mucilage ducts. In the earlier stages these cells have walls
not differing from those of the adjacent cells, but as they grow
older the whole cell wall is dissolved, and the space occupied
by the row of young cells becomes an elongated cavity filled
with apparently structureless mucilage. These cells are recog-
nisable at an early period, as their contents are much denser
and more finely granular than those of the adjacent cells.

MOSSES AND PERNS

CHAP.

Small cells, each containing a peculiar oil body, are found
abundantly in most species, both in the body of the thallus
and in the ventral scales. The structure and development of
these curious bodies, which are found also in many other
Hepaticae, have been carefully studied by Pfeffer (2). The
oil body has a round or oval form usually, and in the Mar-
chantiCcX usually is found in a special cell which it nearly fills.
It is brown or yellowish in colour, and has a turbid granular
appearance. The extremely careful and exhaustive study of
these bodies by Pfeffer has shown that the oil exists in the
form of an emulsion in water, and that in addition to the oil
and water more or less albuminous matter is pres-
ent, and tannic acid. The latter is especially
abundant in the oil bodies of Lunidaria, less so in
Marchantia and Frt'/^^/a( Cavers (6) ; Kiister ( i ) ).
The thallus of the Marchantiace?e is made up al-
most entirely of parenchyma, but Goebel (3)
states that in Prcissia coinimitata there are elon-
gated sclerenchyma-like cells in the midrib. The
walls of the large colourless cells of the lower lay-
ers of the thallus are often marked with reticulate
thickenings, which are especially conspicuous in
Marchantia.

Most of the Marchantiaceai have no special non-
sexual reproductive organs, but in the genera

Fig. 12. — Mar- ,, , ,. . j ,. .,

chantia poly- Marcliautia. and Liuiulana special gemmae are pro-
nto r p h a . {[^-^qqq[ Jii enormous numbers; and in the latter
tubercuiate form, which is extremely common in greenhouses,
rhizoid , tiie plant multiplies only by gemmae, as the plants
are apparently all female. These gemmae, as is
well known, are produced in special receptacles upon the dorsal
side of the thallus. The receptacles are cup-shaped in Mar-
cJiantia, and crescent-shaped in Lunuhiria, where the forward
part of the margin of the cup is absent. These cups are appar-
ently specially developed air-chambers, which, closed at first,
except for the central pore, finally become completely open.
The edge of the fully-developed receptacle is fringed. The
gemmae arise from the bottom of the receptacle as papillate
hairs, and their development is the same in the other two genera
where they occur. Fig. 13 shows their development in M.
polymorpha.

M USCINE^—HEPA TIC^—MARCHANTIALES

One of the surface cells of the bottom of the receptacle
projects as a papilla above the surface, and is cut off by a
transverse wall from the cell below. The outer cell next
divides again by a transverse wall into a lower cell, which
develops no further, and a terminal cell from which the gemma
is formed. This terminal cell first divides into two equal cells
by a cross-wall (Fig. 13, B), and in each of these cells a similar
wall arises, so that the young gemma consists of four nearly

Fig. 13. — Marchantia polymorpha. A, Plant with gemma cups {k, k), Xz; B-F,
development of the gemmae, Xs^s; G, an older gemma, X260; v, v' , the two
growing points.

equal superimposed cells (Fig. 13, D). The wall III in Fig.
13, D, arises a little later than wall II, and is always more or
less decidedly concave upward. Each of the four primary
cells of the gemma is divided into two by a central vertical wall,
and this is followed by periclinal w^alls in each of the resulting
cells. At first the gemma is but one cell in thickness, but
later walls are formed in the central cells parallel to the sur-
face, so that it becomes lenticular. As it grows older there

46 MOSSES AND FERNS chap.

is established on opposite sides (Fig. 13, G, v, v') the grow-
ing points, which soon begin to develop in the manner found in
the older thallus, and come to lie in a depression, so that the
older gemnicT are fiddle-shaped. The gemma stands vertically,
and there is no distinction of dorsal and ventral surfaces. The
cells contain chlorophyll, except here and there the cells with
oil bodies, and an occasional large colourless superficial cell.
Among them are small clul>shaped hairs, which secrete a
mucilage that swells up when wet, and finally tears away the
gemmae from their single-celled pedicels.

The further development of the gemmae depends upon their
position as to the light. Whichever side happens to fall down-
ward becomes the ventral surface of the young plant, and the
colourless cells upon this surface grow out into the first rhi-
zoids. The two growing points persist, and the young plant
has two branches from the first, growing in exactly opposite
directions. As soon as it becomes fastened to the ground the
dorsiventrality is established, and upon the dorsal surface the
special green lacunar tissue and the epidermis with its charac-
teristic pores are soon developed, while the ventral tissue loses
its chlorophyll, and soon assumes all the characters found in
the mature thallus.

The branching of the thallus is in most cases dichotomous,
as in Riccia, but occasionally, as in Targionia (Fig. i, F), the
growth is largely due to the formation of lateral adventitious
branches produced from the ventral surface.

In structure and development the sexual organs correspond
closely to those of the Ricciaceae, but they are always formed
in more or less distinct groups or "inflorescences." As might
be expected, this is least marked in the lower forms, especially
the Corsinieae (Leitgeb (7), vol. iv.), where the main distinc-
tion between them and the lower Ricciaceae is that in Corsinia
the formation of sexual organs is confined to a special region,
and that the archegonia do not have an individual envelope as
in Riccia, but the whole group of archegonia is sunk in a com-
mon cavity, which is of exactly the same nature as that in
which each archegonium is placed in the latter. In most of
the Marchantieae, however, both antheridia and archegonia
are lx)rne in special receptacles, which in the case of the latter
are for the most part speciallv modified branches or systems of
branches, raised at maturity upon long stalks (Fig. 21). The

II MUSCINEJE— HEPATIC^— MARCHANTIALES 47

antheridial receptacles are sometimes stalked, but more com-
monly are sessile, and often differ but little from those of the
higher Ricciacese.

The sporogonium shows an advance upon that of the
Ricciacese by the development of a lower sterile portion, or foot,
in addition to the spore-bearing portion or capsule, and in the
latter there are always sterile cells, which in all but the lowest
Corsinieas have the form of elaters. At maturity, also, the ripe
capsule breaks through the calyptra, except in the Corsiniese,
wdiere, too, the sterile cells do not develop into elaters, but
seem to serve simply as nourishing cells for the growing
spores. The stalk of the capsule is usually short compared
with that of most Jungermanniacese, and the wall of the capsule
remains intact until the spores are ripe.

The spores vary much in size, and in the development of
the outer wall. In Marchantia polyinorpha and other species
where the spores germinate promptly, the ripe spore contains
chlorophyll, and the exospore is thin and slightly developed.
In such cases there is no distinct rupture of the exospore, but
the whole spore elongates directly into the germ-tube. In
Conocephalus, where the spores are very large, the first divi-
sions occur in the spores before they are scattered. In species
where the spores do not germinate at once the process is much
like that of Riccia, and the thick exospore is ruptured and
remains attached to the base of the germ-tube.

The apical growth of the Marchantieae is very much like
that of Riccia. In Fimbriarta Calif ornica (Fig. 14) the apical
cells seen in vertical section show the same form as those of
Riccia, and the succession of dorsal and ventral segments is
the same; but here the development of the ventral segments
is much greater, and there is not the formation of the median
ventral lamellae as in Riccia, but the two rows of ventral scales
arise independently on either side of the midrib, very near the
growing point, and closely overlap and completely protect the
apex. The formation of the lacunae in the dorsal part of the
thallus begins earlier than in Riccia, and corresponds very
closely to what obtains in Ricciocarpus. The pits are at first
very narrow, but widen rapidly as they recede from the apex.
In the epidermal cells surrounding the opening of the cavity,
there are rapid divisions, so that the opening remains small
and forms the simple pore found in this species. As in Riccio-

MOSSES AND FERNS

CHAP.

carpus, the original air-chambers become divided by the devel-
opment of partial diaphragms into secondary chambers, which
are not, however, arranged in any regular order, and communi-
cate more or less with one another.

In Targionia (Figs. i8, 19), where the archegonia are
borne upon the ordinary shoots, the growth of the dorsal seg-
ments is so much greater than that of the ventral ones that the
upper part of the thallus projects far beyond the growing point,

which is pushed under
toward the ventral side.
A similar condition is
found in the archegonial
receptacles of other
for m s, where this in-
cludes the growing point
of the shoot (Fig. 21).
In Targionia the lacun?e
are formed much as in
Fiinhriaria, but they are
shallower and much wid-
er, and the pores corre-
spondingly few. The as-
similative tissue here re-
sembles that of Mar-
thantia and others of the
higher forms. It is
sharply separated from
the compact colourless
tissue lying below it, and
the cells form short con-
fervoid filaments more
or less branched and an-
astomosing, and except in the central part of the chamber united
with the epidermal cells. Under the pore, however, the ends
are free and enlarged with less chlorophyll than is found in
other cells.

All of the ]\Iarchantie?e except the aberrant genera Dumor-
tiera and Mnnnclca correspond closely to one or the other of the
above types in the structure of the thallus, but in the latter the
air-chambers are either rudimentary or completely absent, and
the ventral scales are also wanting. Leitgeb ( (7), vi., p. 124)

Fig. \^.— Fimbriaria Californica. A, Vertical sec-
tion through the apex of a sterile shoot, show-
ing the formation of the air-chambers ; x, the
apical cell, X300; B, similar section through
an older part of the thallus. cutting through a
pore, X 100.

n MUSCINE/E—HEPA TICJE— MARCH ANTIALES 49

investigated D. irrigua, whose thallus is characterised by a
pecuhar areolation composed of projecting cell plates, and
came to the conclusion that these were the remains of the walls
of the air-chambers, whose upper parts, with the epidermis,
were thrown off while still very young. He had only herba-
rium material to work with, but in this he detected traces of the
epidermis and pores in the younger parts. I examined with
some care fresh material of D. trichoccphala, from the Hawa-
iian Islands, and find that in this species, which has a perfectly
smooth thallus without areolations, that no trace of air-cham-
bers can be detected at any time. Vertical sections through
the apex show the initial cells to be like those of other Marchan-
tiace?e, and the succession of segments the same, but no indi-
cations of lacunae can be seen either near the apex or farther
back, the whole thallus being composed of a perfectly contin-
uous tissue without any intercellular spaces, and no distinct
limit between the chlorophyll-bearing and the colourless tissue.
As Duinortiera corresponds in its fructification with the higher
Marchantie.x, the peculiarities of the thallus are probably to
be regarded as secondary characters, perhaps produced from
the environment of the plant, and species like D. irrigua would
form transitional stages between the typical Marchantiaceous
thallus and the other extreme found in D. trichoccphala.

Sexual Organs

The structure and development of the sexual organs are
very uniform among the Marchantiaceae. In Fimhriaria Cali-
fornica, which is dioecious, the antheridial receptacle forms a
thickened oval disc just back of the apex. Not infrequently
(Fig. I, A), when the formation of antheridia begins not long
before the forking of the thallus, both of the new growing
points continue to develop antheridia for a time, and the recep-
tacle has two branches in front corresponding to these. The
receptacle is covered with conspicuous papilke which mark the
cavities in which the antheridia are situated. Vertical longi-
tudinal sections through the young receptacle show antheridia
in all stages of development, as their formation, like those of
Riccia, is strictly acropetal. The first stages are exactly like
those of Riccia, and the primary cell divides into two cells, a

pedicel and the antheridium proper. The divisions in the lower
4

MOSSES AND FERNS

CHAP.

cell are somewhat irregular, but more numerous than in Riccia,
so that the stalk of the ripe antheridium is more massive
(Fig. 1 6). In the upper cell a series of transverse walls is
formed, varying in different species in number, but more than
in Riccia, and apparently always perfectly horizontal. In
Marchantia polyinorpha Strasburger (2) found as a rule but
three cells, before the first vertical walls were formed. In an
undetermined species of Fimbriaria (Fig. 15) probably F.
Bolmidcvi, the antheridia were unusually slender, and fre-
quently four, and sometimes five transverse divisions are formed
before the first vertical walls appear. Sometimes all the cells
divide into equal quadrants by intersecting vertical walls, but
quite as often this division does not take place in the uppermost

Fig. 15. — Fimbriaria sp. (?). A, Part of a vertical section of a young antheiidial
receptacle, showing two very young antheridia ((^), X420; B-E, older stages.

and lowest cell of the body of the antheridium, or the divisions
in these parts are more irregular. The separation of the cen-
tral cells from the wall is exactly as in Riccia, and the lower
segments do not take any part in the formation of the sperm
cells, but remain as the basal part of the wall. In Fimbriaria
the top of the antheridium is prolonged as in Riccia, but in
Marchantia this is not the case. The wall cells, as the anther-
idium approaches maturity, are often much compressed, but
in Targioiiia hypophylla, where Leitgeb states that this com-
pression is so great that the cells appear like a simple membrane,
I found that, so far from this being the case, the cells were
extraordinarily large and distinct, and filled the whole space
between the body of the antheridium and the wall of the cavity,
which in Leitgeb's figures ((7), vi., PI. x., Fig. 12) is repre-

MUSCINE^—HEPA TIC^— MARCH ANTI ALES

sented as empty. The antheridium becomes sunk in the thallus
precisely as in Riccia. The sperm cells are nearly cubical and
the spermatozoid is formed in the usual way. The free
spermatozoid (Fig. 16, D) shows about one and a half com-
plete turns of a spiral. The cilia are very long, and the vesicle
usually plainly evident.

According to Ikeno (4), in Marchantia polymorpha the
final division, resulting in the pair of spermatids, is unaccom-
panied by a division wall, and this seems also to be the case in

Fig. 16.— Fimbriaria Californica. A. Longitudinal section of a fully-developed male
receptacle, X8; B, longitudinal section of a nearly ripe antheridium, Xioo; C,
young sperm cells, X6oo; D, spermatozoids, X1200.

Fimbriaria. In the earlier divisions of the sperm-cells, each
cell shows two centrosomes (Fig. 17, i), and Ikeno does not
recognise any difference between these and the so-called
''blepharoplast" of Webber and other recent students of sperma-
togenesis, who look upon the blepharoplast as a different organ
from the centrosome. After the final division, each spermatid
is provided with a single centrosome (blepharoplast), from
which, later, the cilia arise.

MOSSES AND FERNS

CHAP,

The young spermatid (Fig. 17, 3) is triangular in section,
and the blepharoplast is situated in the acute angle which later
forms the anterior end of the spermatozoid. The blepharoplast
becomes somewhat elongated, and from it grow out the two
cilia before any marked change is observable in the nucleus.
(Fig. 17, 5). Before the cilia can be seen, there appears in the
cytoplasm a round body which stains strongly, but whose origin
is not clear. This body Ikeno calls the chromatoid ''Neben-
korper," and says that it does not participate directly in the
development of the spermatozoid, but ultimately disappears.
His figures 30 and 31, however, look as if the portion of the
spermatozoid between the blepharoplast and the nucleus was
derived from this "nebenkorper," and not from the cytoplasm,
as he states is the case.

Fig. 17. — Marchantia poly)norfha. Development of the spermatozoid, i. Sperm-cells
from the young antheridium; 2, final division of the sperm-cell to form the two
spermatids; 2-7, development of the spermatozoid; b, blepharoplast; p, "neben-
korper"; (All figures after Ikeno).

Owing to the very small size of the spermatozoids in
Marchantia, it could not be positively demonstrated whether
there is a cytoplasmic envelope about the nuclear portion of the
spermatozoid, but it was concluded that such probably is the
case.

When the antheridia are borne directly upon the thallus,
the apical growth continues after antheridia cease to be formed,
and the receptacle is thus left far back of the growing in point.
In forms like Targionia, however, where there are special
antheridial branches, the growth of these is limited, and gener-
ally ceases with the formation of the last antheridia. The most

II MUSCINEJE— HEPATIC JE— MARCH ANTI ALES S3

specialised forms are found in the genus Marchantia and its
allies, where the antheridial receptacle is borne upon a long
stalk, which is a continuation of the branch from which it
grows, and the receptacle is a branch-system. The growing
point of the young antheridial branch forks while still very
young, and this is repeated in quick succession, so that there
results a round disc with a scalloped margin, each indentation
marking a growing point, and the whole structure being equiva-
lent to such a branch system as is found in Riccia or Anthoccros,
where the whole thallus has a similar rosette-like form. The
antheridia are arranged in radiating rows, the youngest one
nearest the margin and the eldest in the centre. In some
tropical species, e.g., M. geminata, the branches of the receptacle
are extended and its compound character is evident.

The discharge of the spermatozoids from the ripe anther-
idium may take place with great force. In the case of
Fimbriaria Calif ornica, Peirce (i) found they were thrown
vertically for more than fourteen centimetres. The mechanism
involved includes not only the tissues of the antheridium itself,
but also the cells below the antheridium, and those forming the
walls of the chambers in which the antheridia are situated.
These cells, becoming strongly distended with water, exercise
great pressure upon the antheridium, whose mucilaginous con-
tents are also strongly distended. The upper wall of the
antheridium is finally burst, and the contents expelled violently
through the narrow, nozzle-like opening of the antheridial
chamber.

This explosive discharge was first noted by Thuret (i) in
Conoccphaliis coniais, and has been recently studied in that
species by King (i) and Cavers ( i), as well as in several other
genera. It is much more marked in the dioecious species.

The archegonia are never sunk in separate cavities, but
stand free above the surface of the thallus. The simplest form
may be represented by Targionia. Here the archegonia arise
in acropetal succession from the dorsal segments of the initial
cells of the ordinary branches. A superficial cell enlarges and
is divided as in Riccia into an outer and an inner cell. The
latter undergoes irregular divisions and its limits are soon lost.
In the outer cell the divisions occur in the same order as in
Riccia, but from the first the base of the archegonium is broad
and not tapering. Strasburger (2) states that in Marchantia

MOSSES AND FERNS

CHAP.

there is a division of the outer of the two primary cells by a
wall parallel to the first, and that the lower one forms the foot
of the archegonium, and Janczewski ( i ) gives the same account
of the young archegonium of Preissia commutata. This cer-
tainly does not occur in Targionia, and to judge from the later
stages of Fiinhriaria Calif ornica, this species too lacks this

Fig. i8. — Targionia hypophylla. A, Longitudinal section of the thallus, Xioo; ar,
archegonia; / /. ventral scales; B, median section through a pore, showing the
assimilating cells (c/) below, X300.

division. The full-grown archegonium is of more nearly
uniform thickness than in Riccia, as the venter does not become
so much enlarged. The neck canal cells are more numerous,
about eight being the common number, but in Targionia the
formation of division walls between these is sometimes sup-

MUSCINE^—HEPA TIC^— MARCH ANTI ALES

pressed (Fig. 19, C), so that this may account for Janczewski's
error in stating that the number was always four, as the nuclei
in unstained sections might very easily be averlooked. The
cover cells are somewhat smaller than in Riccia and do not
usually undergo as many divisions, there being seldom more
than six in all. In Targionia (Fig. 23, A), and Strasburger
((21), p. 418) observed the same in Marchantia, the ripe ^gg
shows a distinct "receptive spot," that is, the upper part of the
unfertilised Qgg is comparatively free from granular cytoplasm,
while the lower part, about two-thirds in Targionia, is much
more densely granular. The nucleus is not very large and has
very little chromatin. The nucleolus is large and distinct and

/ A,

Fig. 19. — Targionia hypophylla. A, Longitudinal section of the apex of the thallus,
with young archegonia {ar), X525; x, the apical cell; B, young, C, older arche-
gonium in longitudinal section; D, cross-section of the archegonium neck, X52S.

Stains very intensely. As the archegonium of Targionia
matures, its neck elongates rapidly and bends forward and
upward, no doubt an adaptation to facilitate the entrance of
the spermatozoid. A similar curving of the archegonium neck
is observed in other forms where the archegonium is upon the
lower side of the receptacle.

After an archegonium (or sometimes several of nearly
equal age) is fertilised, the growth in length of the thallus stops.

MOSSES AND FERNS

THAP.

but there is a rapid lateral growth with results in the formation
of two valves, which meet in front much like the two parts of
a bivalve shall, and this involucre completely encloses the devel-
oping sporogonium.

In the simplest cases, where the archegonia are borne upon
a receptacle^ whicli is raised upon a stalk, e.g., Phgiochasma,
Clcvca (Fig. 20, A), the receptacle does not represent, accord-
ing to Leitgeb ( (7), vi., p. 29), a complete branch, but is only a
dorsal outgrowth of the latter, which may grow out beyond' it,
or even form several receptacles in succession. Tlie first indi-
cation of tlie recep-

tacle is a dorsal prom-
inence whicli soon be-
comes almost hemi-
spherical, and near the
_ .— v: hinder margin the first
archegonium arises,
without, apparently,
any special relation to
the growing point.
On the lateral margins
are then formed two
other archegonia, not,
however, simultane-
ously; and finally a
fourth may be formed
in front : three or four
archegonia in all seem
to be the ordinary

Fig. 20.-A. Chvea sp. A, longkudinal section of 'l^^nil^er. TllC Stalk of

the thallus showing the dorsal origin of the fc- tllC rCCCptaclc is alsO

male receptacle ($) ; r, the growing point (dia- .1^,-,,^1 nnnpnrHo-p ni

gram after Lcitgcb) ; B, Reboulia hemisphwrica ^ < 'Ol ^ai appCnCiage OI

(Radd.), longitudinal section of very young re- tllC tlialluS, aud UOt 1

ceptacle with the first archegonium (Q) ; x, the i • - .• .•

apical cell. X300 (after Leitgeb). ^ d 1 r C C t COntinUatlOU

of it.
The next type is that whicli Leitgeb attributes to GriiuaJdia,
Reboulia, Fimbriaria, and some others, but it is not tlie tvpe
found in Fimbriaria Calif ornica. In this type tlie structure of

"The sporongotiial receptacle of the Alarchantierc is sometimes known as
the Carpocephalnm.

MUSCINEJE— HEPATIC^— MARCH ANTI ALES

the receptacle and the origin of the archegonia are the same
:is in that just described; but here the growing point of the

Fig. 2i.—Fimhriaria Californica. A, Plant with two fully-grown sporogonial recep-
tacles, natural size; B, single receptacle, X4; C, the same cut longitudinally,
showing the sporogonium {sp), enclosed in the perianth {per); D, nearly median
section of a young receptacle, showing one growing point (..r) and an arche-
gonium (or); L, air-spaces; st, a pore; r, rhizoids, X40; E, the growing point of
the same with an archegonium, X300; x, the apical cell.

Dranch forms the forward margin of the receptacle, and the
stalk is a direct continuation of the axis of the branch, Upon

58 MOSSES AND FERNS chap.

its ventral surface it shows a furrow in which rhizoids are
produced in great numbers, and this furrow^ continues along
the ventral surface of the thallus.

The highest type is that of Leitgeb's "Composit?e." In this
form the female receptacle is a branch system similar to that
of the male receptacle of Marchantia. The branching is usually
completed at a very early period, while the receptacle is almost
concealed in the furrow in the front of the thallus. A simple
case of this kind is seen in Fimbriaria Calif ornica (Fig. 21).
In this case there are four growing points that have arisen from
the repeated dichotomy of the primary growing point of the
branch, and each of these gives rise to archegonia in acropetal
succession, much as in Targionia, but the number of archegonia
is small, not more than two or three being as a rule formed from
each apex. The development of the dorsal tissue is excessive
and the ventral growth reduced to almost nothing, and the
growing apices are forced under and upward and lie close to
the stalk, and the archegonia have the appearance of being
formed on the ventral side of the shoot, although morphologic-
ally they are dorsal structures. In the common Marchantia
polymorpha the branched character of the receptacle is empha-
sised by the development of the "middle lobe" between
the branches. These lobes grow out into long cylindrical
appendages between the groups of archegonia, and give the
receptacle a stellate form. Usually in M. polymorpha there
are eight growing points in the receptacle, and of course as
many groups of archegonia, which are more numerous than in
any other genus, amounting to a hundred or more in one recep-
tacle. In Marchantia, as well as some other genera with com-
pound receptacles, there are tw^o furrows in the stalk, showing
that the latter is influenced by the first dichotomy. While the
archegonia, before fertilisation, are quite free, the whole group
of archegonia, and indeed the Avhole receptacle, is invested with
hairs or scales of various forms that originate either from the
epidermis of the dorsal side, or as modifications of the ventral
scales.

The peculiar American genus Cryptoniitriuiu has been
investigated by Abrams ( i ) and Howe (3), who finds the devel-
opment of the carpocephalum to agree essentially with that of
Fimbriaria Californica. Cavers (6, 7, 8), has recently investi-
gated that of Conoccphalus {Fcgatclla) , Rcboiilia and Prcissia.

n MUSCINE^— HEPATIC^— MARCH ANTI ALES 59

The lacunar tissue is very much developed upon the
receptacles, as are to an especial degree the peculiar cylindrical
breathing pores. The formation of these begins in the same
way as the simple ones, being merely the original opening to
the air-space. This seen from the surface shows an opening
with usually five or six cells surrounding it. Vertical sections
show that very soon the cells surrounding the pore become
deeper than their neighbours and project both above and below
them. In these cells next arise (Fig. 11, A, B) a series of
inclined walls by which each of the original cells is transformed
into a row of several cells, and these rows together form a
curious barrel-shaped body surrounding the pore. The upper
cells converge and almost close the space above, and this is still
further diminished by the cuticle of the outer cell wall of the
uppermost cells growing beyond the cells and leaving simply
a very small central opening. The rows of cells also converge
below, and in Fimhriaria Calif ornica the lowermost cells are
very much enlarged, and probably serve to close the cavity
completely at times, and act very much like the guard cells of
the stomata of vascular plants. In Leitgeb's group of the
Astroporae, the simple pores of the thallus have the radial walls
of the surrounding cells strongly thickened, so that the pores
seen from the surface appear star-shaped. The most special-
ised of the Marchantieae, /. c, Marchantia, Prcissia, etc., have
the cylindrical pores upon the vegetative part of the thallus as
well as upon the receptacle, but in the others they occur only
upon the latter.

The Sporophyte.

The first divisions in the embryo of the Marchantiacese and
Corsiniacea^ are the same as in the Ricciaceae, but only the
upper part (capsule) of the sporogonium develops spores,
while the rest becomes the stalk and foot. The simplest form
of capsule is found in the genera Corsinia and Boschia, which
have been carefully studied by Leitgeb ((7), iv., pp. 45-47).
In these the embryo, instead of remaining globular as it does in
Riccia, elongates and very early becomes differentiated into a
nearly globular upper part, or capsule, and a usually narrower
basal portion, the foot (Fig. 22). In the capsule at a very
early period a single distinct layer of outer cells is separated
from the central group of cells, and forms the wall of the

6o MOSSES AND FERNS chap.

capsule, which in Bosch ia at maturity develops upon the inner
cell walls thickened bars. Only a portion of the cells of the
central part produce spores ; the remainder do not divide after
the spore mother cells are formed, but remain either as simple
slightly elongated nourishing cells (Corsiiiia) or elaters
(Boschia).

The other Alarchantiacene are much alike, and as Targioiiia
was found to be an especially satisfactory form for study, on
account of the readiness with which straight sections of the
embryo could be made, it was taken as a type of the higher
Marchantiales. The first division wall (basal wall) is trans-
verse, and divides the embryo into two nearly equal parts.
This is followed in both halves by nearly vertical walls
(quadrant walls), and these and the basal wall are then
bisected by the octant walls, so that as in Riccia the young

embryo is formed of eight nearly equal
cells. In Targionia, even at this
period, the embryo is always somewhat
elongated instead of globular. The
next division walls vary a good deal in
different individuals. Fig. 23, C
shows a very regular arrangement of
cells, where the first divisions were
much the same in all the quadrants.
Here all the secondary walls were
nearly parallel with the basal wall, and
intersected the quadrant and octant
walls; but quite as often, especially in
the upper half of the embryo, these
secondary walls may intersect the basal
wall. In no cases seen was there any
indication of a two-sided apical cell
such as Hofmeister figures for Tar-

FiG. 22. — Corsinia march an- . . . 111 1 •

tioicics. voun« sporogo- gjoiiia, aud probably his error arose
nium. optical section. X300 from a studv of foHTis Avhcrc the quad-

(Leitgeb). „ ' ,.,.,.

rant walls were somewhat mclmed, m
which case the intersection of one of the secondarv walls with
it might cause the apex of the embryo to be occupied by a cell
that, in section, would appear like the two-sided apical cell of
the Moss embryo. The regular formation of octants was ob-
served by me in Fimbriaria Calif ornica, and by Kienitz-Gerloff

MUSCINE^— HEPATIC^— MARCH ANTI ALES

(i, 2) and others in Mar chant ia, Gr'wialdia, and Preissia, and
probably occurs normally in all Marchantiacese.

After the tirst anticlinal walls are formed in the octants, no

Fig. 23.—Targiorna hypofhylla. A, Longitudinal section of the venter of a ripe
archegonium, X500; B-E, development of the embryo, seen in longitudinal
median section— B, two-celled, D, four-celled stages, X500 except E, which is
magnified 150 times; F, median section of the upper part of an older embryo,
X250.

definite order could be observed in the succeeding cell divisions,
especially in the lower half of the embryo. In the upper part

MOSSES AND FERNS

;hap.

pericllnal walls appear, but not at any stated time, so far as
could be made out, and the first ones do not, as Leitgeb asserts,
necessarily determine the separation of the archesporium, as in
the Corsinieae. The growth now becomes unequal, the cells in
the central zone not dividing so actively, a marked constriction
is formed, and the young sporogonium becomes duml>bell
shaped. By this time a pretty definite layer of cells (Fig.
2^, F) is evident upon the outside of the capsule, but the cells
of the globular lower part, or foot, are nearly or quite uniform.
They are larger than those of the capsule, and more transparent.

Fig. 24. — Targionia hypophylla. A, Median longitudinal section of older embryo
enclosed in the calyptra (cal), X8o; B, a portion of the upper part of the same
embryo, X480; the nucleated cells represent the archesporium; C, part of the
archesporium of a still later stage; el, elaters; sp, sporogenous cells, X480.

In the latter the wall becomes later more definite, and remains
but one cell thick until maturity. The arrangement of the cells
of the archesporium is very irregular, and until the full number
of these is formed they are all much alike. Just before they
separate, however, careful observation shows that two well-
marked sorts of cells are present, but intermingled in a perfectly
irregular way A part of these cells are nearly isodiametric,
the others slightly elongated, and the nuclei of the former cells

MUSCINE^—HEPA TIC^— MARCH ANTI ALLS

are larger and more definite than those of the latter. At this
stage the cells hegin to separate by a partial deliquescence of
their cell walls, and when stained with Bismarck-brown these
mucilaginous walls colour very deeply, and the cells are very
distinct in sections so treated. They finally separate com-
pletely, and the much-enlarged globular capsule now contains
a mass of isolated cells of two kinds, globular sporogenous
cells and elongated elaters. The former now divide into four
spores, but before the nucleus divides the division of the spores
is indicated by ridges which project inward and divide the
cavity of the mother cell much as in the Jungermanniacese.
With the first divisions in the embryo the venter of the

Fig. 25. — Fimhriaria Californica. A, Young, B, older embryo in median section. A,
X300; B, Xioo; C, upper part of a sporogonium, after the differentiation of the
archesporium, X 200.

archegonium. which before was only one cell thick, divides by
a series of periclinal walls into two layers of cells, which later
undergo further divisions, so that the calyptra surrounding the
older capsule may consist of four or more layers of cells. The
neck of the archegonium remains unchanged, but the tissue of
the thallus below the archegonium grows actively, and sur-
rounds the globular foot, which has grown down into the thallus
for some distance, and only the capsule remains within the
calyptra. This large growth of the foot is at the expense of
the surrounding cells of the thallus, which are destroyed by its

MOSSES AND FERNS

CHAP.

growth, and through the foot nourishment is conveyed from
the thallus to the developing capsule. That is, the sporogo-
nium is here a strictly parasitic organism, growing entirely at
the expense of the thallus.

The further growth of the spores and elaters was studied in
Finihriaria Calif ornica. The spores remain together in tetrads,
until nearlv ripe. In sections parallel to the surface of the
younger spores (Fig. 26, C) the outer surface of the exospore
is covered with very irregular sinuous thickenings, at first
projecting but little above the surface, but afterward becoming
in this species extraordinarily developed. In sections of the

Fig. 26. — Fimbriaria Californica. A, Young elater X6oo; B, a fully-grown clater,
X300; C, surface view of the wall of a young spore, showing the developing
episporic ridges, X6oo; D, section of a wall of a ripe spore, X300.

ripe spore (Fig. 26, D) three distinct layers are evident, the
cellulose endospore, the thick exospore, and this outer thick-
ened mass of projecting ridges which has every appearance of
being deposited from without, and must therefore be charac-
terised as epispore (perinium) ; Leitgeb ((7), vi., p. 45) dis-
tinctly states that thickenings of this character do not occur in
the MarchantiecT, but that the thickenings are always of the
character of those in Riccia.

II MUSCINE^— HEP ATICM— MARCH ANTI ALES 65

The elaters are at first elongated thin-walled cells with a
distinct although small nucleus, and nearly uniformly granular
cytoplasm. As they grow the cytoplasm loses this uniform
appearance, and a careful examination, especially of sections,
shows that the granular part of the cytoplasm begins to form
a spiral band, recalling somewhat the chlorophyll band of
Spirogyra. This is the beginning of the characteristic spiral
thickening of the cell wall, and while at first irregular, the
arrangement of the granular matter becomes more definite, and
following the line of this spiral band of granules in the cyto-
plasm, there is formed upon the inner surface of the wall the
regular spiral band of the complete elater. This band, which
is nearly colourless at first, becomes yellow in the mature elater,
and in Targionia, where there are generally two, they are
almost black. Not infrequently branched elaters are found,
but these are unicellular, and no doubt owe their peculiar form
to their position between the spore mother cells in the young
archesporium. An axial row of granules, which seem to be
of albuminous nature, remains in the elaters of Fimhriaria
until maturity.

The differences in the structure of the sporogonium in
dift'erent genera of the Marchantiere are slight. In Marchantia
polymorplia, the young sporogonium is nearly globular, and
even when full grown it is ellipsoid with the stalk and foot
quite rudimentary. Most forms, however, have the foot large,
but the stalk, compared with that of most Jungermanniacere, is
short. • In most of them the whole of the upper half of the
young embryo develops into the capsule, but in Fimhriaria
Calif ornica I found that the archesporium was smaller than in
other forms described, and that sometimes the apical part of
the sporogonium Avas occupied by a sort of cap of sterile cells
(Fig. 25, C).

When ripe, the cells of the capsule-wall in Targionia de-
velop upon their walls dark-colored annular and spiral thicken-
ings much like those of the elaters. These thickenings are
quite wanting in Fimhriaria.

The dehiscence of the capsule is either irregular, e.g..
Targionia, or by a sort of lid, e.g., Grimaldia, or by a number
of teeth or lobes, e.g., Liimilaria, Marchantia. In some forms
after fertilisation there grows up about the archegonium a cup-
shaped envelope, "perianth, pseudoperianth," which in Fim-
5

MOSSES AND FERNS

CHAP.

hriaria especially is very much developed, and projects far
beyond the ripe capsule (Fig. 21).

The germination of the spores corresponds in the main with
that of Riccia. Except in cases where the exospore is very
thin, in which case it is not ruptured regularly, the exospore
either splits along the line of the three converging ridges upon

Fig. 27. — Targionja hypophylla. Germination of the spores, X about 200. In B two
germ tubes have been formed; C and E are optical sections; x, apical cell; r,
primary rhizoid; sp, spore membrane.

the ventral surface, and through this split the endospore pro-
trudes in the form of a papilla, as in Riccia; or in Targionia
(Fig. 2^) the exospore is usually ruptured in two places on
opposite sides of the spore, and through each of these a filament
protrudes, one thicker and containing chlorophyll, the other
more slender and nearly colourless. The first is the germ tube,
the second the first rhizoid. In Finihriaria Californica the
first rhizoid usually does not form until a later period. In
Targionia a curious modification of the ordinary process is
quite often met with (Fig. 27, B). Here, by a vertical divi-
sion in the very young germ tube, it is divided into two similar
cells, which both grow out into germ tubes. Whether
both of these ever produce perfect plants was not determined,
but the first divisions in both were perfectly normal. The
first divisions in the germ tube are not quite so uniform as in

II MUSCINE^—HEPA TIC^— MARCH ANTI ALES 67

Riccia trichocarpa, but resemble tbem very closely in the com-
moner forms.

In Fimbriaria especially, and this has also been observed
in Marchantia (Leitgeb (7), vi., PI. ix., Fig. 13) and other gen-
era, a distinct two-sided apical cell is usually developed at an
early period, and for a time the growth of the young plant is due
to the segmentation of this single cell. Finally this is replaced
by a single four-sided cell (Fig. 29, C), very much like the
initial cell of the mature thallus. The young plant, composed
at first of homogeneous chlorophyll-bearing cells, grows rapidly
and develops the characteristic tissues of the older thallus.
The first rhizoids are always of the simple form, and the

papillate ones only arise later,
as do the ventral scales. Tar-
gionia shows a number of pe-
culiarities, being much less
uniform in its development
than Fimbriaria. While it
often forms the characteristic
germ tube, and the divisions
there are the same as in Riccia
and Fimhriaria, the formation
of a germ tube may be com-
pletely suppressed, and the

Fig. zS.—Targionia hypophylla. Germ f^j-g^ rCSUlt of gCrminatioU is
plant in which the thallus (T) has . ., /• i • t.

been formed secondarily, X260. oftCU a CCll maSS, from whlCh

later a secondary germ tube
may be formed with the young plant at the apex (Fig. 28).
Such cases as these are the only ones where it seems really
proper to speak of the plant arising secondarily from a proto-
nema, for in other cases, as in Riccia, the growth is perfectly
continuous, and the axis of the young thallus is coincident
with that of the germ tube, and^n no cases observed by me
could it in any sense be looked upon as a secondary lateral
growth.

Biology of the Marchantiaceae

While the Marchantiaceae are, as a rule, moisture-loving
plants, still some of them are markedly xerophilous. Most of
the commoner Californian species, e.g., Fimhriaria Californica,
Targionia hypophylla, Cryptomitrium teneritm, dry up com-

Fig. 2g.—Fimbriaria Californica. A, B, Young plants in optical section, showing the

single two-sided apical cell (.r;, X260; C, horizontal section of an older plant

with a single four-sided initial (jr), X425; D, E, two young plants, D from
below, E from the side, X8s.

n MUSCINE^—HEPA TIC^— MARCH ANTI ALES 69

pletely during the long rainless summer, and revive imme-
diately with the advent of the autumn rains. In these species,
the growing point of the thallus, with a good deal of the
adjacent tissue, survives, and at once becomes fresh and active.
The scales and mucilage-cells found about the apex are doubt-
less water conservers, and according to Cavers (3, 6, 7), the
tuberculate rhizoids are also concerned in holding water. In
Finihriaria Calif or nica, even the young antheridia survive the
long summer drought.

It has been shown (Cavers (6, 7)), that the large hyaline
cells terminating the green assimilating filaments in the air-
chambers of such forms as Conocephalus and Targionia are the
principal agents in the transpiration of water from the under-
lying tissues.

Besides the formation of definite gemmae like those of
Marchantia and Liinnlaria, the thallus in most Marchantiacese
is capable of extensive regeneration, even from small frag-
ments. In Conocephalus there have also been found tuberous
outgrowths, which are formed under certain conditions and
are doubtless for propagation (Cavers (6)).

The Marchantiaceae are readily separable into two sub-
families, the Targionieae, and the Marchantiese. Leitgeb
has made a further division of the latter family, but some of
the characters given are not sufficiently constant to warrant
his division, and for that reason it has been thought best not
to accept them. Thus Fimhriaria Californica, wdiich is, in
regard to its fructification, typical, has the female receptacle
of the composite type, a character which, according to Leitgeb.
not only does not belong to the genus Fimhriaria, but is not
found in any genus of the group (Operculatae) to which he
assigns it. This species too does not have the capsule opercu-
late, but opens irregularly.

The Targionieae include the two genera Targionia, which
has been already described at length, and Cyatlwdiuin (Leitgeb
(7), vi., p. 136), whose development is not sufficiently known
to make its systematic position quite certain. In the position
of the sexual organs, and the formation of the two-valved
involucre about the fruit, as well as the position of the latter, it
corresponds closely to Targionia, but the structure of the thallus
is extraordinarily simple, there being practically but two layers
of cells with large irregular air-chambers between. While two

TO MOSSES AND FERNS chap.

sorts of rhizoids are present, those that represent the papillate
type of the other IMarchantiacese, while thicker walled than
the others, do not dev^elop the projecting prominences. Indeed
the whole structure of the plant is curiously reduced, and
Leitgeb describes it as resembling the young plants of Mar-
chantia or Prcissia. The development of the sexual organs is
but imperfectly known, and the suggestion of Leitgeb's that
possibly the antheridium is reduced to a single cell, seems hardly
probable in view of the structure of the rest of the plant. The
sporogonium has the stalk and foot exceedingly rudimentary,
but the upper part of the capsule shows a zone of cells whose
walls are marked by peculiar ring-shaped thickenings, and opens
regularly by a number of teeth, which on account of the thick-
ened bars upon the cell wall offer a superficial resemblance to
the peristome of the Bryales. As in Targionia the archegonia
arise near the apex of the ordinary shoots, and no proper
receptacle is formed.

All of the other forms have the archegonia borne upon a
special receptacle, which, as the sporogonia develop, is raised
upon a stalk. Here belong, according to Schiffner ( i ) sixteen
genera with about 150 species. The receptacle may be, as we
have seen, strictly dorsal in origin, or it may include the grow-
ing point of the archegonial branch, or finally it may be a
branch system arising from the repeated dichotomy of the
original growing point.

MONOCLEA

The genus Monoclca includes two known species, M.
Forsteri, found in New Zealand and Patagonia, and M.
Gottschei, of Tropical America, said also to occur in Japan.
This genus has been usually associated with Jungermanniales
(Leitgeb (7), vol. iii., Schiffner (i)), but a more complete
study of the plant has shown that its affinities are undoubtedly
more with the simpler Marchantiacese. The structure and posi-
tion of the sexual organs, especially the antheridia, and the
development of the sporophyte, so far as it has been made out
(Cavers (7), Johnson (3)), all point unmistakably to a rela-
tionship with the Alarchantiaceae.

Two kinds of rhizoids are present, although not so marked
as in the typical Marchantiaceae, but the thallus lacks the char-

II MUSCINEJE—HEPA TIC^— MARC HAN TI ALES 71

acteristic lacunar tissue of these forms. In the latter respect
Monoclca closely resembles Dtiinorticra, and as in that genus,
the absence of the air-chambers may be attributed to the semi-
aquatic habit of the plant. Monoclca evidently belongs to the
lower series of Marchantiaceae, and may perhaps be compared
to Targionia. See Ruge (i), Cavers (7), Campbell (19).

Resume of the Mar chant ialcs

Comparing the different members of this order, one is struck
by the almost imperceptible gradations in structure between the
different families, and this accounts for the dift'erence of opinion
as to where certain genera belong. That the Ricciaceae cannot
be looked upon as a distinct order is plain, and they may perhaps
be best regarded as simply a family co-ordinate with the Cor-
siniese and Targioniege, and not a special group opposed to all
the other Marchantiaceae. The gradual increase in complexity
of structure is evident in all directions. First the thallus passes
by all gradations from Riccia — with its poorly defined air-
chambers with no true pores and single ventral lamellae,
through Ricciocarpns and Tcssalina, where definite air-cham-
bers are present, opening by pores of the same form as those of
the lower Marchantieae, and separate ventral scales occur — to
forms like Marchantia, where the air-chambers are very definite
and contain a special assimilating tissue, and the pores are of
the cylindrical type. With this differentiation of the thallus
is connected the segregation of the sexual organs and the devel-
opment of special receptacles upon which they are borne.
Finally, in the development of the sporogonium, while there is
almost absolute uniformity in the earlier stages, we find a
complete series of forms, beginning with Riccia, where no stalk
is developed and all the cells of the archesporium develop spores,
ascending through Tcssalina, with a similar absence of a stalk,
but the first indication of sterile cells, through the Coi'siniccc, to
forms with a massive foot and elaters fully developed. It
may be said, however, that there is no absolute parallelism be-
tween the development of the gametophyte and that of the
sporophyte; for in Marchantia, the most specialised genus as
to the gametophyte, the sporogonium is less developed than in
the otherwise simpler Targionia and Finihriaria.

CHAPTER III

THE JUNGERMANNIALES

A VERY large majority of the Hepatic?e belong to the
Jungernianniales, which show a greater range of external dif-
ferentiation than is met with in the Marchantiacere, Ixit less
variety in tlieir tissues, the whole plant usually consisting of
almost uniform green parenchyma. In the lowest forms, e.g.,
Aneiira and Mctzgeria, the gametophyte is an extremely simple
thallus, in the former composed of almost perfectly similar
cells, in the latter showing a definite midrib. Starting with
these simplest types, there is a most interesting series of transi-
tional forms to the more specialised leafy ones, where, however,
the tissues retain their primitive simplicty. All of the Junger-
manniales grow from a definite apical cell, which differs in
form, however, in different genera, or even in different species
of the same genus. Rhizoids are usually present, but always
of the simple thin-walled type.

The gametophyte, with the exception of the genera Haplo-
mitriuiu, and Calohrynni, is distinctly dorsiventral, and even
when three rows of leaves are present, as in most of the foliose
forms, two of these are dorsal and lie in the same plane, while
the third is ventral. In the thallose forms, while the bilaterality
is strongly marked, there is not the difference between the
tissues of the dorsal and ventral parts which is so marked in
the Marchantiales. In the lowest forms the gametophyte is a
simple flat thallus fastened to the substratum by simple rhizoids,
and develops no special organs except simple glandular hairs
which arise on the ventral side near the apex, and whose muci-
laginous secretion serves to protect the growing point. In
Blasia and Fossombronia we have genera that while still retain-
ing the flattened thalloid character, yet show the first formation

Ill THE JUNGERMANNIALES 72

of lateral appendages which represent the leaves of the true
foliose forms. In the latter the axis is slender, and the leaves
usually in three rows and relatively large.

The archegonia correspond closely in their development to
those of the Marchantiace?e, and in the lower (anacrogynous)
forms arise in much the same way from surface cells of the
dorsal part of the younger segments, and the apical cell is not
directlv concerned in their formation. The archesfonia in these
thus come to stand singly or in groups upon the dorsal surface
of the thallus, whose growth is not interrupted by their develop-
ment. In the higher leafy forms (Jungermanniacese acro-
gynse) they occur in groups at the end of special branches,
whose apical cell finally itself becomes the mother cell of an
archegonium, and with this the growth in length of the branch
ceases.

The antheridia in most cases dififer essentially in their first
divisions from those of the Marchantiaceae. After the first
division in the mother cell, by wdiich the stalk is cut off from the
antheridium itself, the first wall in the latter, in all forms inves-
tigated except Sphccrocarpiis, Riella and Geothalhis, is
vertical, instead of horizontal, and the next formed walls are
also nearly vertical. The ripe antheridium is usually oval in
outline and either nearly sessile or provided with a long pedicel.
The spermatozoids are as a rule larger than in the Marchan-
tiales, and show more numerous coils, but like those of the lat-
ter, are ahvays biciliate.

The embryo differs in its earliest divisions from that of the
Marchantiacese. The first transverse wall divides the embryo
into an upper and lower cell, but of these the lower one usually
takes no further part in the development of the sporogonium,
but either remains undivided or divides once or twice to form a
small appendage to the base of the sporogonium. In the upper
cell the first wall may be either vertical {c. g., PelUa and most
anacrogynous forms), or it may be transverse. From the
upper of the tT\'o primary cells not only the capsule but the seta
and foot as well are formed. The development of these differ-
ent parts varies in different forms, and wall be taken up when
considering these.

All of the Jungermanniales, except the Anelaterese, possess
perfect elaters, but in the latter these are represented merely by
sterile cells that probably serve simply for nourishing the grow-

74 MOSSES AND FERNS chap.

ing spores. The sporogonium remains within the calyptra
until the spores are ripe, when by a rapid elongation of the cells
of the seta it breaks through the calyptra, which is left at its
base, and the capsule then opens. The opening of the capsule
is usually effected by its walls splitting into four valves along
lines coincident with the first formed vertical cell walls in the
young embryo. These valves, as well as the elaters, are
strongly hygroscopic, and by their movements help to scatter
the ripe spores. The latter show much the same differences
observed in the Marchantiace?e. When the spores germinate
at once they have abundant chlorophyll and a thin exospore, but
where they are exposed to drying up, they have no chlorophyll
and the exospore is thick and usually wnth characteristic thick-
enings upon it. From the germinating spore the young
gametophyte may develop directly, or there may be a well-
marked protonemal stage. This latter is always found in the
foliose forms, and is either a flat thallus, like the permanent
condition of the lower thallose genera, or sometimes (Proto-
cephalozia) it is a branched filamentous protonema, very much
like that of the JMosses, and sometimes long-lived and produc-
ing numerous gametophores.

Non-sexual reproductive bodies in the form of unicellular
gemnicX are found in many species, and in Blasia special
receptacles with multicellular gemmae something like those of
AlarcJianfia occur.

The Jungermanniales naturally fall into two well-marked
series,^ Anacrogyuce and Acrogynae, based upon the position
of the archegonia. These in the former are never produced
directly from the apical cell of a branch, in the latter group
the apical cell of the archegonial branch always sooner or later
becomes transformed into an archegonium. The Haplomitrie?e
show some interesting intermediate forms between the two
groups, but all the other Jungermanniales examined belong
decidedly to one or the other. As a rule the Anacrogynae are
thallose (the "frondose" forms of the older botanists), but a
few genera, especially Fossouibrouia, show a genuine fonnation
of leaves. All the Acrogynae have a distinct slender stem with
large and perfectly developed leaves.

' Prof. L. M. Underwood proposes the name ^Metzgeriacere for the Ana-
crogynre, reserving the name Jungermanniace<e for the Acrogyn^e. These
two groups he considers co-ordinate with the Marchantiales and Antho-
cerotes.

Ill THE JUNGERMANNIALES 75

ANACROGYN^

Jungermanniales Anacrogynae. Apical cell of female axis
never becoming transformed into an archegonium.

A. Anelatere?e. No true elaters, but sterile cells repre-
senting these. Capsule cleistocarpous. Four genera,
Thallocarpiis, Sphccrocarpiis, Riella, Gcothalhis.
E. Elatereae. Capsule opening either by four valves or
irregularly. Elaters always developed.

a. Gametophore always dorsi ventral, either strictly
thallose or with more or less developed leaves. Fam-
ilies,— Metzgerie.x, Leptothecese, Codoniese.

b. Gametophore upright with three rows of radially ar-
ranged leaves. Fam. I., Haplomitriese.

Anelatere^

The simplest form belonging here is Splicer ocarpns, a genus
that shows certain affinities with the Ricciaceae, but on the
whole seems to be more properly placed at the bottom of the
series of the Jungermanniales.

Sphccrocarpus terrestris occurs in Europe and the south-
eastern United States. In California it is replaced by two
species, ^. Californicus and 5^. cristatns, which until recently
(Howe (3)) were not recognised as distinct, and were con-
sidered to be a variety of .S'. terrestris. They are small plants
growing upon the ground, usually in crowded patches, where,
if abundant, they are conspicuous by the bright green colour of
the female plants. The males are very much smaller, often less
than a millimetre in diameter, and purplish in colour, so that
they are easily overlooked. The thallus is broad and passes
from an indefinite broad midrib into lateral wings but one
cell in thickness (Fig. 30). The forward margin is occupied
by a number of growing points formed by the rapid dichotomy
of the original apex, and separated only by a few rows of cells.
From the lower side of the thallus grow numerous rhizoids
of the thin-walled form. The whole upper surface is cov-
ered with the sexual organs, each of which is surrounded by
its own very completely developed envelope.

A vertical section passing through one of the growing
points (Fig. 30, C) shows a structure closely like a similar
section of Riccia. The apical cell (,r) produces dorsal and

MOSSES AND FERNS

CHAP.

ventral segments, and from the outer cells of the former the
sexual organs arise exactly as in Riccia. On the ventral sur-
face the characteristic scales of Riccia are absent, and are re-
placed by the glandular hairs found in most of the anacrogy-
nous Jungermanniales.

The development of the archegonium shows one or two
peculiarities in which it differs from other Hepaticae. The
mother cell is much elongated, and the first division wall, by

Fig, 30. — SphccrocarpHs Calif amicus (?). A, Male plant, X40; (^. antheridia; B,
median section of a similar plant, X8o; C, the apex of the same section, X240;
h, ventral hair.

which the archegonium itself is separated from the stalk, is
some distance alx)ve the level of the adjacent cells of the
thallus, so that the uj^per cell is very much smaller than the
lower one. The upper cell has much denser contents than the
lower one, which instead of remaining undivided as in Riccia,
divides into two nearly equal superimposed cells, this division

Ill

THE JUNGERMANNIALES

taking place about the same time as the first division in the
archegonial cell (Fig. 31, B). The divisions in the latter are
the same as in Riccia, and the general structure of the arche-
gonium offers no noteworthy peculiarities. The number of
neck canal cells is small, probably never exceeding four, and in
this respect recalls again Riccia. The central cell is relatively
large, and the ventral canal cell often nearly as large as the
egg. As the archegonium develops, its growth is stronger on
the posterior side, and it thus curves forward. At first the
young archegonium projects free above the surface, but pres-

FiG. 31. — Sphccrocarpus sp. (?). Development of the archegonium. A-C, Longi-
tudinal sections, X6oo; D, X300.

ently an envelope is formed about it exactly as in Riccia, but
arising at a later stage. After this has begun to form, its
growth is very rapid, and it soon overtakes the archegonium
and grows beyond it, and finally forms a vesicular body, plainly
visible to the naked eye, at the bottom of which the arche-
gonium lies. The formation of this involucre is quite inde-
pendent of the fertilisation of the archegonium, and as these
peculiar vesicles cover completely the whole dorsal surface of
the plant, they give it a most characteristic appearance. Usu-
ally each archegonium has its own envelope, but Leitgeb ( (7),

78 MOSSES AND FERNS chap.

iv., p. 68) states that two or even more may be surrounded
by a common envelope. When ripe, the venter of the arche-
gonium is somewhat enlarged, but not so much as in Riccia.
The egg-cell is very large, oval in form, and nearly fills the
cavity of the single-layered venter.

The first wall in the embryo is transverse, and divides the
egg cell, which before division becomes decidedly elongated,
into two nearly equal cells. Ordinarily in each of these cells
similar transverse walls are formed before any vertical walls
appear, so that the embryo consists of a simple row of cells.
As in the Marchantiace?e the first wall separates the future
capsule from the stalk, and in this respect SpJiccrocarpus
approaches the Marchantiales rather than the Jungermanni-
ales. Following the transverse walls there are formed in all
the upper cells nearly median vertical ones, which are inter-
sected by similar ones at right angles to them, so that in most
cases (although this is not absolutely constant) the upper half
of the young sporogonium at this stage (Fig. 32, A) consists
of two tiers, each consisting of four cells. The lower part of
the embryo is pointed, and the basal cell either undergoes no
further division or divides but once by a transverse wall, and
remains perfectly recognisable in the later stages (Fig. 32, B,
C). The other cells of the lower half divide much like those
of the upper half, but the divisions are somewhat less regular.

There next arise in all the cells of the upper half periclinal
walls, which at once separate the wall of the capsule from the
archesporium. This wall in the later stages (Fig. 32, C, D) is
very definite, and remains but one cell thick up to the time the
sporogonium is mature. The further divisions in the capsule
are without any apparent order, and result in a perfectly glob-
ular body composed of an outer layer of cells enclosing the
archesporiuin, which consists of entirely similar cells with
rather small nuclei and dense contents. While these chancres
are going on in the capsule, the lower part of the embryo loses
its originally pointed form, and the bottom swells out into a
bulb (the foot), which shows plainly at its base the original
basal cell of the young embryo. This bulb is characterised by
the size of the cells, which are also more transparent than those
of the other ])arts of the embryo.

Owing to the development of the stalk of the archegonium,
after fertilisation the whole embrvo remains raised above the

Ill

THE JUN GERM ANN I ALES

level of the thallus, instead of penetrating into it, as is usually
the case. The stalk or portion l^etween the capsule and foot
remains short, and in longitudinal section shows about four

Fig. 32. — Spharocarpus sp (?). A, B, Median longitudinal sections of the arche-
gonium venter, with enclosed embryos, X260; C, an older sporogonium in median
section, X260; D, a still later stage, showing the large space between the arche-
sporial cells and the wall, X85.

rows of cells. As the calyptra grows the upper part becomes
divided into two layers, the part surrounding the foot into
three. Instead of breaking through the calyptra at maturity.

8o MOSSES AND FERNS chap.

the capsule grows faster than the calyptra long before it is
mature, and the upper part of the calyptra is first compressed
very much and finally completely broken through by the en-
larging capsule.

Leitgeb calls attention to the fact that soon after the
cells of the archesporium begin to separate, the whole mass
of cells becomes completely separated from the wall of the
capsule, which grows rapidly until the cavity within is much
larger than the group of archesporial cells, which thus float
free in the large cavity. Fig. 32, D shows a section through
a sporogonium at this stage. The cells making up the central
mass are apparently alike, but in the living sporogonium part
of the cells have abundant starch and chlorophyll, while in the
others these are wanting or present in much less cjuantity,
while their place is taken by oil, but no rule could be made
out as to the distribution of the two sorts of cells. The latter
are the spore mother cells, while the others are gradually used
up by the developing spores. The spores in .S'. tcrrcstris remain
united in tetrads, and escape from the capsule by the gradual
decay of its wall and of the surrounding tissue of the gameto-
phyte.

The male plants are very much smaller than the females,
with which they grow and under which they are at times
almost completely hidden. The cell walls of the antheridial
envelopes are often a dark purple-red colour, and this makes
them much harder to see than the vivid green female plant.
The apical growth and origin of the antheridium is the same
as in Riccia. The first division in the primary antheridial
cell is the same as in that of the archegonium, but the basal
cell is smaller, and does not divide again transversely, and
takes but little part in the formation of the stalk. In the an-
theridium mother cell are next formed two transverse walls,
dividing it into three superimposed cells. The two uppermost
divide, as in the MarchantiacCcX, by vertical median walls into
regular octants, the lower by a series of transverse walls into
the stalk, which consists of a single row of cells sunk below the
level of the thallus. After the division of the body of the
antheridium into the octant cells, periclinal walls are formed
in each of these, so that the body of the antheridium consists
of eight central cells and eight peripheral ones, and the stalk
of two cells, of which the upper one forms the base of the

Ill

THE JUNGERMANNIALES

antheridium body (Fig. 33, D). At this stage and the one
preceding it Sphccrocarpus recalls the structure of the anther-
idium of the Characese, although the succession of walls is
not exactly the same. The divisions of the central cells are ex-
tremely regular, walls being formed at right angles, so that
the sperm cells are almost perfectly cubical, and the limits of
the primary central cells are recognisable for a long time.

The development of the antheridial envelope begins much
earlier than that about the archegonium, but in exactly the
same way. By the time that the wall of the antheridium is
formed the envelope has already grown up above its summit,
and as the antheridium develops it extends far beyond it like
a flask, at the bottom of which the antheridium is placed, and
through whose neck the spermatozoids escape. These are

A B £

Fig. 33. — Sphccrocarpus sp (?). Development of the antheridium. A-D, Median lon-
gitudinal sections, X450; E, an older one, X225; F, a spermatozoid, killed with
osmic acid, X900.

very much like those of the other Hepaticse, and in size exceed
those of most of the Marchantiaceae, but are smaller than is
usual among the Jungermanniales.

Leitgeb studied the germination of the spores in vS. terres-
tris, which remain permanently united in tetrads. He found
that all the spores of a tetrad were capable of normal develop-
ment, which does not differ from that of Riccia or other thal-
lose Liverworts. A more or less conspicuous germ tube is
found at the end of which the young plant develops, one of the
octants of the original terminal group of cells becoming, appar-
ently, the apical cell for the young plant. The latter rapidly

grows in breadth and soon assumes all the characters of the
6

MOSSES AND FERNS

CHAP.

older plant. Leitgeb (Fig. 17, PI. IX.) shows a condition
that looks as if at an earlier stage a two-sided apical cell had
been present, but he says nothing in regard to this. The
sexual organs appear while the plant is extremely small. Leit-
geb says he observed the first indications of them on individ-
uals only one millimetre in diameter, and before the first papil-
late hair on the ventral surface had been formed.

In the commonest Calif ornian species, wS'. crista fits the
spores separate completely at maturity. The early stages of
germination are like those in vS. ferrcstris. There is usually
a two-sided apical cell at first, which later is replaced by the
type found in the adult thallus.

Fig. 34. — Geothallus tuberosus. A, Male plant, X15; B, section of female plant, X15;

t. young tuber.

Where there is an excess of moisture the thallus may be-
come much larger than usual, this being especially noticeable
in the male plants. There is often, under these conditions,
a development of leaf-like marginal lobes. This excessive
vegetative development of the thallus is accompanied by a
marked diminution in the number of the sexual organs.
(Campbell (17)).

Geothallus.

Evidently closely allied to Sphccrocarpns is a remarkable
Liverwort, as yet found only near San Diego, in Southern

Ill

THE JUN GERM ANN I ALES

California (Campbell (18)). Gcothallus tiibcrosus (Figs.
34, 35), differs from Splucrocarpus in its much larger size,
the development of leaf-like organs, much like those of Fos-
somhronia and by the very much larger size of the spores.
There are also some minor differences in the structure of the
reproductive organs, the antheridia having a more massive
pedicel than that of Sphccrocarpiis. The plants are perennial,
and at the end of the growing season the younger parts of the
thallus become changed into a tuber with- a thick black cover-
ing. The tubers are buried in the earth during the dry season.

Fig. 35. — Geothallus tuberosus. A, Archegonium, X200; B, ripe antheridium, X about
65; C, a four-celled embryo, X200; D, ripe spore; E, sterile cells, Xioo.

The apex of the shoot persists and resumes growth as soon
as the conditions are favorable.

Riella.

•

The peculiar genus RicUa (Goebel (17), Leitgeb (7), Por-
sild (i)), while it closely resembles Sphcurocarpus in the struc-
ture of the reproductive organs and sporophyte, differs very
much in the habit of the gametophyte. Until very recently
( Howe and Underwood ( 3 ) ) , all the species known were
from the regions adjacent to the Mediterranean, but one species
has since been found in the Canary Islands, and another in the
United States. They are all submersed aquatics. The thal-
lus shows a cylindrical axis, from w^hich grows a thin vertical

MOSSES AND FERNS

CHAP.

dorsal lamina or wing, which may be more or less spirally
placed, owing to torsion of the axis, but this torsion was much
exaggerated in the early figures of the original species, R.
hcUcophylla. According to Goebel's investigations, the grow-
ing point is formed secondarily, and this statement is con-
firmed by Howe's studies. The latter writer has studied the
germination of the spores and has described the formation of
gemm?e in R. Americana.

The latest contrilmtion to our knowledge of RicIIa is that
of Porsild (i). He confirms Howe's statements and has

Fig. 36. — A. D, Riclla Americana; B, C, R. hcUcophylla; A, Apex of female plant, X8;
B, C, lateral and ventral view of the growing point, X500; x, apical cell ; Z,, leaves.
D, male plant, Xi%; (A, D, after Howe ; B, C, after Leitgeb.)

further investigated the question of the growing point. He
finds that while an apical cell is absent in the younger stages,
it is formed later in normal plants.

Both archegonia and antheridia resemble those of SpJiccro-
carpiis very closely, and the structure of the sporophyte is also
the same, no true elaters being developed, but instead there
are simply sterile cells.

Ill

THE JUNGERMANNIALES

Elatereae

Aneiira and Metzgeria represent the simplest of the typical
anacrogynous Jungermanniales. In the former the thallus
is composed of absolutely similar cells, all chlorophyll-bearing,
and in each cell one or more oil bodies, like those of the Mar-
chantiacese. In Metzgeria (Fig. 37) the wings of the thallus
are but one cell thick, and there is a very definite midrib, usu-
ally four cells thick. The apical growth in both genera is

Fig. 37. — Metzgeria pubescens. A, Surface view of the thallus in process of division,
X80; B, growing point of a branch showing the two-sided apical cell (.r) and the
ventral hairs (h), X240; C, the growings point in process of division, x, x', the
apical cells of the two branches, X480.

the same, and is effected by the growth of a ''two-sided"
apical cell.^ The segmentation is very regular, especially in
Met!:geria (Fig. 37), where each of the segments divides first
into an inner and an outer cell, the former by subsequent divi-
sions parallel to the surface of the thallus producing the thick-

^Leitgeb (7), vol. iv.

MOSSES AND FERNS

CHAP.

ened midrib, the outer cells dividing only by perpendicular
walls, forming the wings. From the ventral surface of the
young midrib papillae project, which curve up over the grow-
ing point, in the form of short two-celled hairs, whose end
cells secrete mucilage for its protection. In Aiieura the growth
is very similar, but all of the cells divide by walls parallel to
the surface of the thallus, and no midrib is formed, and the
thallus is several cells thick in all parts. In both genera numer-
ous delicate colourless rhizoids are developed from the ven-
tral surface, especially of the midrib, when that is present.

Aneura is of interest as showing the only case among the
Bryophytes of structures that may be compared to the zoo-

Fig. 38. — A, Symphyogyna sp.; B, Hymenophyton liabcllatum, XiJ^; sp., young
sporophyte; b, young shoot.

Spores of the Green Algae. In A. mulfi/ida Goebel ((8), p.
S37), discovered that the two-celled gemmre which had been
described as formed simply by a separation of the cells of the
thallus, were really formed within the cells and expelled from
them through an opening, after which they divided into two
cells and ultimately developed a young plant, much as an ordi-
nary spore would do. The absence of cilia from these cells,
which probably are the last reminiscences of the ciliated go-
nidia of the aquatic ancestral forms, is to be accounted for by
the terrestrial habit of Aneura.

The branching is dichotomous, and is brought about by

Ill

THE JUNGERMANNIALES

the formation of a second apical cell in one of the youngest
segments. This apical cell is formed by a curved wall, which
strikes the outer wall of the segment (Fig. 2i7y C). Thus
two apical cells arise close together, and as segments are cut
off from each, they are forced farther and farther apart, and
serve as the growing point of two shoots, which may continue

Fig. 39. — Aneura pinnatifida. A, Part of a thallus with two antheridial branch, s
slightly magnified; B, an archegonial branch, X40; C, cells from the margin cx
the archegonial branch showing the oil bodies (o), Xsoo-

to grow equally, when the thallus shows a marked forking
(M. f areata), or one of the branches grows more strongly than
the other, which is thus forced to one side and appears like a
lateral branch {Aneura pinnatiiida, Fig. 41, B).

In certain species of Pallavicinia and Symphyogyna, and
especially in Hymenophyton (Fig. 38, B), the gametophyte
shows a differentiation into a prostrate rhizome-like sterj,

MOSSES AND FERNS

CHAP.

from which arise upright flattened shoots which are repeatedly
forked, so that there is a remarkably close superficial resem-
blance to the fan-shaped leaves of certain Ferns, especially
some of the smaller Hymenophyllaceae. This resemblance is
heightened by the very distinct midrib traversing each thallus-
segment.

Sexual Organs.

The sexual organs in both Aueura and Metzgeria are borne
on short branches, which in the latter arise as ventral struc-

FiG, /^o.-—Aneura pinnatifida. A, Horizontal section of the apex of a young antheridial
branch, X565; x, the apical cell; ^, antheridia: B, transverse section of a young
archegonial branch, passing through the apical cell (.r) ; ^, young archegonia,
X525; C, longitudinal section of a nearly ripe archegonium, X262; D, E,
spermatozoids of Pcllia calycina, X1225 (D, E, after Guignard).

tures, but in Aueura are simply ordinary branches that are
checked in their growth by the production of the sexual or-
gans, and not infrequently may grow out into ordinary
branches after the formation of the sexual organs has ceased.
In A. pinnatifida (Fig. 39, B), archegonia and antheridia are
usually produced upon separate branches, but may occur to-
gether.

The origin of the antheridia can be readily followed in

Ill

THE JUNGERMANNIALES 89

sections made parallel to the surface of the male branch. The
apex is occupied by an apical cell of the usual form, and the
cell divisions in the young segment are extremely regular.
The segment first divides into an inner and an outer cell, and
the former probably next into a dorsal and a ventral one. The
dorsal cell divides by a longitudinal wall into two nearly equal
cells, of which the inner one, dividing by a wall perpendicular
to the first, gives rise to the primary cell of the antheridium
(Fig. 40, A<^). This cell now projects above the surface of
the thallus, and divides into a single stalk cell, which under-
goes no further divisions, and the antheridium mother cell.
The divisions in the latter correspond to those in the other
Jungermanniales. First a vertical wall is formed, dividing
the young antheridium into two equal parts. Next, in each
of these, two walls arise intersecting each other as well as the
median wall, and dividing each half of the antheridium into
three cells, two peripheral ones and a central one. (A some-
what later stage than this is shown in Fig. 40, A.) The per-
ipheral cells do not reach to the top of the antheridium, and
next a periclinal wall is formed near the top of the central cells,
by which a third peripheral cell is formed in each half of the
antheridium, which now consists of two central cells and six
peripheral ones. The further divisions were not followed in
detail, but seem to correspond with those in the higher forms.

Of the two first cells into which the dorsal cell divides, the
one which does not produce the antheridium together with the
inner of the two into which that cell first divides, form a par-
tition which rapidly increases in height with the growth of
the antheridia, and separates each from its neighbour by a
single layer of cells, so that the antheridia are sunk in cham-
bers, arranged in two rows, corresponding to the two series
of segments of the apical cell.

In the other thallose anacrogynous forms, e. g., Palla-
vicinia (Fig. 41, A), the sexual organs are borne upon the
dorsal surface of the ordinary shoots, usually surrounded by
a sort of involucre. In most of these forms the apical cell is
of a different type from that of Anciira, but is variable even
in the same species. Thus in PaUavicmia cylindrica, while
the commoner form is nearly wedge-shaped, appearing four-
sided seen from the surface, and triangular in vertical section,
it may approach very nearly the two-sided type (Fig. 42, C).

MOSSES AND FERNS

CHAP.

In the ordinary form four sets of segments are cut off, — dorsal
and ventral, as in Riccia or Sphccrocarpus, and two sets of
lateral ones. In Pcllia calycina the apical cell shows a similar
form, but in P. cpiphylla (Fig. 42, D, E), another type is
seen. Here, while the surface view is the same as in P. caly-

FlG. 41.— A, Pallavicinia cylindrica, X4; per, the elongated perianth; B, Ancura pin-
natitida, X6; J, archegonial branches; C-E, Fossombronia longiseta, X4; 1'. Blasia
pusilla, X4.

cina, in vertical section the cell is nearly semicircular, i. e., here
there are but three sets of segments, two lateral ones and a
basal one, extending the whole depth of the thallus, and only

Ill

THE JUNGERMANNIALES

Fig. 42. — A, Vertical, B, C, horizontal sections through the apex of Pallavicinia
cylindrica; x, apical cell. A, X225; B, C, X450; D, E, Pellia epiphylla; D, ver-
tical section; E, horizontal (optical) section, X450.

MOSSES AND FERNS

CHAP.

later showing a division into ventral and dorsal cells. Prob-
ably this type has been derived from the former by a gradual
increase in the size of the angle formed by the dorsal and ven-
tral walls of the apical cell, which finally became so great as
to practically form one plane.

The antheridium of PcUia is larger than that of Aneura,
but its development is very similar except that the stalk is
multicellular, as it is in the other Anacrogynre. The sperma-
tozoids of PcUia (Fig. 40, D, E), are much larger than those
of Aneura, but are exceeded in size by those of the allied genus
Makinoa (Aliyake (2)).

Fig. 43.— Fw^om&roMia longiseta; early stages in the development of the antheridium,
X525; drawings made by Mr. H. B. Humphrey. D, cross-section.

In Fossomhronia (Fig. 43), which in several respects re-
calls SphccrocarpMS or Geothallus, the first divisions in the an-
theridium are median ones, so that in both longitudinal and
transverse sections the antheridium appears to be divided into
equal quadrants. The first division, however, is vertical, as it
is in Aneura.

The archegonia are borne upon similar but shorter
branches and their development also is very regular. In Fig. 40,
B, a vertical section through the end of a young female branch
is shown with the apical cell {x). Segments are here, too, cut

Ill

THE JUNGERMANNIALES

off alternately right and left, and from each segment an arche-
gonium develops. The segment is first divided, probably, as
in the male branch and the vegetative ones, into an inner and
an outer cell, but I did not succeed in getting satisfactory longi-
tudinal sections parallel to the surface, so cannot speak posi-
tively on this point. The youngest segment, in which the
archegonium mother cell is recognisable, shows in vertical sec-
tion three cells, a small ventral one, a middle larger one, and
a dorsal one — the archegonium mother cell. The latter does
not form any stalk, but divides at once by the three intersect-
ing walls, as in other Hepaticae, and the further development
corresponds with these, except that the base of the archegonium

Fig. 44. — Fossomhronia longiscta. Development of the archegonium, longitudinal sec-
tion, X525; drawings made by Mr. H. B. Humphrey.

is not free, and the central cell is below the level of the super-
ficial cells of the thallus. The archegonium neck is short, and
the basal part as wxll as that part of the venter which is free,
two cells thick (Fig. 40, C). The number of neck cells is
small (apparently about four), but whether the number is con-
stant cannot be stated positively. The female branch remains

^ MOSSES AND FERNS chap.

very short, and the archegonia, which are only produced in
small numbers (usually not more than six to eight), are close
together and surrounded by an irregular sort of envelope
formed by the more or less incurved and very much laciniated
margins of the branch. Secondary hair-like growths are also
formed, so that to the naked eye the archegonial receptacles
appear as densely fringed and flattened tufts upon the sides of
the larger branches.

The archegonium of Fossombronia (Fig. 44) closely re-
sembles that of Sphccrocarpiis, but it ordinarily has but five
peripheral rows of neck-cells, as in most of the Jungerman-
niales. Occasionally, however, there may be six rows, as in
Sphccrocarpiis.

Janczewski ( i ) followed very carefully the development of
the archegonium in Pcllia cpiphylla, which differs a good deal
from that of Aneiira. The archegonia are formed in groups
just back of the apex, but he does not seem to have been able to
detect any relation between them and the segments of the
apical cell such as obtains in Anciira, but it seems probable that
such a relation does exist. After the archegonium mother
cell is cut off, it does not at once divide by vertical walls, but
there is first cut off a pedicel, after which the upper cell under-
goes the usual divisions. Of the three peripheral cells one is
much smaller and does not as a rule divide longitudinally, so
that the neck has normally but five rows of cells instead of six,
as in the Marchantiaceae. Owing to the formation of the
pedicel, the archegonium is quite free at the base, and like that
of Anciira the wall of the venter is two-lavered. The neck
becomes very long, and, according to Janczewski, the number
of neck canal cells may reach sixteen or even eighteen.

The Sporophyte

The earliest stages in the embryo are not perfectly known.
Kienitz-Gerloff ( i ) investigated Met::gcria furcata and Leit-
geb ((7), III) species of Anciira. In both of these the first
division in the embryo separates an upper cell, from which
capsule and seta develop, from a lower cell, which forms a
more or less conspicuous appendage at the base of the foot.
The earliest divisions in the upper part are not known, but it
soon becomes a cylindrical body consisting of several tiers of

Ill

THE JUN GERM ANN I ALES

cells, each composed of four equal quadrant cells. According
to Leitgeb ( i ) , the upper tier, from which the capsule develops,
is formed by the first transverse wall in the upper part of the
embryo. This upper tier is next divided by nearly transverse
walls into four terminal cover cells, and four larger ones below,
and these latter are again divided each into three cells, an inner
one and two outer ones, so that the capsule consists of four
central cells, the archesporium, and twelve wall cells (Fig. 45,
A). A similar division in the lower tiers results in the forma-
tion of four axial rows and a single outside layer of cells in
the stalk. In the lowest tiers the divisions are much less regu^
lar, and the foot, which is not very largely developed, shows

Fig. 45. — A, Young embryo of Ancura multifida, optical section, X235 (after Leit-
geb); B, median longitudinal section of an older sporogonium of A. pinguis, X35;
C, upper part of B, X200; sp, sporogenous cells; el, young elaters; m, apical group
of sterile cells.

no definite arrangement of the cells. The part of the wall of
the capsule formed from the four cover cells later become two-
layered, but the rest remains but one cell thick. In Metzgeria
(Leitgeb (7), III.) the wall becomes later two-layered. The
archesporium divides first into two layers. In the upper
cells the divisions are more regular than in the lower one,
and later the archesporium is made up of cells arranged in
more or less regular lines, starting from just below the apex
and radiating from this point, extending to the base of the
capsule. These cells are at first of similar form, and with

MOSSES AND FERNS

CHAP.

the growth of the capsule become elongated with pointed
ends that fit together without any spaces between. Some
of these cells, however, divide rapidly by transverse walls
and give rise to rows of isodiametric cells (Fig. 45, sp),
wedo-ed in between others that have remained undivided (el).

The former are the young
A . sporogenous cells, the

latter the elaters. A mass
of cells lying just below
the apex, and belonging
to the archesporium, re-
mains but little changed,
and forms the point of
attachment for the elaters
after the capsule opens
(Fig. 45, B, C, m). See
also Goebel ((21), pp.

325-327-

The further develop-
ment of spores and ela-
ters is similar to that in
the higher Marchantia-
cese, and when the cap-
sule is mature it opens by
four valves which extend
its whole length.

The first division-wall
in the embryo of Fos-
somhronia lougiseta is
transverse and divides it
into two somewhat un-
equal cells, of which the

Fig. 46. — Fossombronia longiscta. A, Section JQ-yygj- and Smaller OUC

through a young tetrad of spores; B, surface . • - .1 r i. 1

view of the wall of a young spore; C, two glVCS nse tO the tOOt, and

young elaters, X600; D, two ripe spores; E, j^^^ merely tO the appCUd-

elaters, X300. . , ^ ' j.u^

age of the foot, as is the
case in Ancura. From the upper cell arise the seta and the
capsule. A second transverse wall (Fig. 47, II.) is formed
before any longitudinal walls appear. The upper of the three
cells gives rise, not only to the capsule, but to part of the seta
as well. The separation of the primary archesporial cells is

THE JUNGERMANNIALES

brought about by a periclinal wall in each of the four terminal
cells, dividing each into an inner archesporial cell, and an
outer wall-cell. (Fig. 47, D.)

The capsule wall in Fossombronia is tw^o cells in thickness,
except at the apex, where it may be three cells thick. The
inner layer of cells, when the capsule is ripe, have irregular
thickened bars developed upon the surface of the radial cell-
walls.

The development of the sporogonium is best known in
Fellia epiphylla (Kienitz-Gerloff (i), Hofmeister (i) ). Here
the first wall, as in Aneura, separates a lower cell, which sim-
ply forms an appendage, from the upper cell, from which the

Fig. 47. — Fossombronia longiseta. Development of the embryo, XS^SJ B, E, cross-
sections; D, shows one of the primary, archesporial cells. Figures drawn by
Mr. H. B. Humphrey.

Stalk and capsule develop. In the latter the first wall is ver-
tical, and is followed in each of the resulting cells by horizontal
walls, by which the separation of the capsule from the seta is
effected. These four cells are now divided by vertical walls,
so that two layers of four cells each are present. The first
periclinal walls in the apical group of cells separate the arch-
esporium from the wall of the capsule.

98 MOSSES AND FERNS chap.

The differentiation of the capsule and seta follows as in
Aneiira, and the arrangement of the cells of the archesporium
is much the same except that the rows of cells radiate from the
base of the capsule and not from the summit. The foot is
very distinct and forms a pointed conical cap, whose edges
overlap the base of the seta.

Spore-division in Anacrogyncs

According to Farmer (4), in Pallavicinia dccipicns there is
formed, previous to the division of the nucleus, a ''quadripolar"
nuclear spindle, extending into each of the four lobes of the
spore mother-cell. Then follows a double division of the
chromosomes, resulting in sixteen, of which four move to each
pole of the spindle to form at once the four nuclei of the spore
tetrad. In Aneura miiltifida the formation of a quadripolar
spindle was also found, but there were subsequently two suc-
cessive nuclear divisions of the usual type. From his study of
Pellia epiphylla, Davis (3) has questioned the accuracy of
Farmer's statements, and Moore's (i) studies on Pallavicinia
Lyalii show that in this species, although a structure which
might be interpreted as a quadripolar spindle is present, there
are two successive divisions of the nucleus with bi-polar spin-
dles. However, the second mitosis follows without an inter-
vening resting stage of the nucleus.

The growth of the seta after the spores are ripe is ex-
tremely rapid, but consists entirely in a simple elongation of
the cells. Askenasi (i) has investigated this in Pellia epi-
phylla, and states that in three to four days the seta increases
in length from about i mm. to in some cases as much as 80
mm., and that this extraordinary extension is at the expense
of the starch which the outer cells of the young seta contain
in great abundance, but which disappears completely during
the elongation of the seta. The growing sporogonium here as
well as in other species is strongly heliotropic.

The calyptra in the thallose Anacrogynre is usually massive,
and in addition there is formed about the growing sporogo-
nium a special envelope inside the involucre, which in Palla-
vicinia especially (Fig. 41, A) becomes prolonged into a tube
which completely encloses the sporogonium until just before its
dehiscence.

Ill THE JUNGERMANNIALES 99

The further development of the spores and elaters corre-
sponds with that of the Marchantiacese (Fig. 46), and
there is the same method of the development of the thicken-
ings upon the walls of the elaters and the spores. In cases
where the spores germinate immediately, chlorophyll is devel-
oped and no proper exospore is formed, although the outer
layer of the cell wall is more or less cuticularised.

In the germination of the spores Pcllia offers an exception
to the other Jungermanniales, in that the spores divide into
a multicellular body before they are discharged from the cap-
sule. The presence of centrospheres in the dividing nuclei
has been demonstrated by Farmer ( 5 ) , and recently Chamber-
lain (2) has studied these bodies very thoroughly in Pellia.
The ripe spore here is an oval body which consists of several
tiers of cells, the end cells being usually undivided, and the
middle ones each consisting of four equal quadrant cells.
There is some disagreement as to the earliest stages in the
germination and the establishment of the apical growth. Hof-
meister ((i), p. 21) states that in P. epiphylla one end cell
of the spore grows out into the first rhizoid, while the other
develops into the growing point of the young plant. Miiller,
N. J. C. ( (i), p. 257), on the other hand, states that in P. caly-
cina both ends of the spore develop rhizoids while the growing
point, which at first has a two-sided apical cell, like that of
Metzgeria, arises laterally.

The germination of the spores of Aneiira has been studied
by Kny (i) in ^. palmata, and by Leitgeb ( (7), III., p. 48) in
A. pinguis, which agrees in all respects with the former. The
spores, as is usual in the Jungermanniales, have a poorly-de-
veloped exospore, and contain chlorophyll when ripe. Before
any divisions take place, the spore enlarges to two or three
times its original volume, and then elongates and by repeated
cross-walls forms a filament of varying length. In the end
cell next an inclined wall arises, which is met by another nearly
at right angles to it, and thus the two-sided apical cell is
established, and the thallus gradually assumes its complete
form (Fig. 48, A).

Connecting the strictly thallose anacrogynous Hepaticas
with the foliose acrogynous ones, are a number of most in-
structive intermediate forms. Of these Blasia (Fig. 41, F) is
perhaps the simplest. Here the margin of the thallus is lobed,

100

MOSSES AND FERNS

CHAP.

and these lobes, according to Leitgeb's view, are very simple
leaves. In Fossomhronia (Fig. 41, C, D), while the general
thallose form is more or less evident, the leaves are unmistak-
able, and as their development shows, morphologically the
same as the leaves of the acrogynous forms. The most re-
markable form, however, is Trenhia insignis, a very large
foliose Liverwort discovered by Goebel in Java. This has all
the appearance of a very large acrogynous form, and also the

typical three-sided apical
cell ; but in regard to the
position of the sexual or-
gans it is typically ana-
crogynous. These and the
Haplomitrie?e form a per-
fect transition from the
Anacrogynae to the Acro-
gynae.

The multicellular gem-
mae of Blasia have been al-
luded to. They are pro-
duced in long flask-shaped
receptacles, and when ma-
ture form nearly globular
brownish bodies whose
cells contain much oil, an^l
whose stalk consists of n
simple row of cells. Anion?;
them are glandular hair?,
which secrete mucilage, by
the swelling of which the
gemmae are loosened from
their pedicels, as in Mar-
chantia. Similar but sim-
pler gemmae having usually
three cells occur in Trcubia
(Goebel (13)). Blasia is also characterised by the presence
of colonies of Nostoc within the thallus. These occupy cavi-
ties in the bases of the leaves and are normally always present.

TJie HaplomitriecB
The two genera, Haplomitrium and Calohryum, which con-

Fig. 48. — A, Young plant of Aneura palmata

X265 (after Leitgeb) ; B, three views of
a young plant of Pellia calycina, X420
(Leitgeb).

Ill

THE JUNGERMANNIALES loi

stitute this family, differ from all other Hepaticse in having
the leaves radially arranged, and not showing the dorsiventral
form that characterises all the others. The plants are com-
pletely destitute of rhizoids but possess a rhizome-like basal
part, from which the leafy axes arise. The latter have well-
developed leaves arranged more or less distinctly in three rows.
The stem grows from a tetrahedral apical cell, as in the acrog-
ynous forms, but in Haplomitrhtm at least the apical cell does
not develop into an archegonium. The archegonia are in this
genus borne at the end of ordinary shoots, but in Calobryum
the end of the female branch becomes much broadened and
the numerous archegonia stand crowded together. In this
case it is possible that the apical cell of the stem may finally
produce an archegonium. Much the same difference is ob-
servable in the arrangement of the antheridia.

The Acrogyn^

Treubia and Haplomitriimi, as we have seen, connect al-
most insensibly the anacrogynous with the acrogynous Jun-
germanniales. The latter are much more numerous than the
former, but much more constant in form, and are doubtless a
later specialized group derived from the former. While dif-
fering in the form and arrangement of the leaves and other
minor details, they are remarkably constant in their method of
growth and in the position of the sexual organs, especially
the archegonia. These are always formed upon special
branches, where, after a varying number of segments are cut
off, the apical cell becomes the mother cell of an archegonium.
The study of any typical form will illustrate the principal
characters of the group. The species selected, Porella (Ma-
dotheca) Bolanderi, is very like the common and widely dis-
tributed P. platyphylla, which corresponds with it in all struct-
ural points.

The plant grows upon rocks, especially, but also upon the
trunks of trees, and forms dense mats closely covering the
substratum. It branches extensively, but always monopodi-
ally, dichotomous branching never occurring in the acrogynous
Jungermanniales. The slender stem is completely hidden
above by the two rows of closely-set, overlapping, dorsal
leaves. Upon the ventral side, which is fastened by scattering

102

MOSSES AND FERNS

CHAP.

rhizoids to the substratum, there is a row of much smaller
leaves (amphigastria), more or less irregularly disposed. The
dorsal leaves, seen from above, are nearly oval in outline, but
each has a smaller ventral lobe, pointed at the tip, and closely
appressed to the lower surface of the much larger dorsal lobe.
The ventral lobes closely resemble the amphigastria, both in
form and size, and with the latter form apparently three rows
of leaves upon the ventral side of the stem. The structure of
the leaf is of the simplest character, consisting of a single layer
of polygonal cells containing numerous chloroplasts.

The plants grow
where they are exposed
to alternate wetting and
drying up. They may at
any stage become com-
pletely dried up, and on
being moistened will re-
sume at once their ac-
tivity. In the dried con-
dition, the species under
consideration often re-
mains for several
months without appa-
rently being injured in
the least, and this power
is shared to a consider-
erable degree by most of
the acrogynous forms,

mum, X4; C, a male plant, X4; r^, the an- , , ^-^ . , , .

theridial branches. WllOSC laVOUrite habitat

is the trunks of trees.
The apical growth of the stem is extremely regular, and as
in all the other acrogynous Hepaticse, the apical cell is a three-
sided pyramid (Fig. 50, A). In longitudinal section it is
much deeper than broad, and its outer face is almost flat. In
cross-sections (Fig. 50, B) it has the form of an isosceles tri-
angle, the shorter side turned toward the ventral surface of the
plant. From this cell three sets of lateral segments are cut off,
two dorsal and one ventral, and each of these gives rise to a
row of leaves, a leaf corresponding to each segment of the
apical cell. The first division wall in each segment is at right
angles to its broad faces and divides it into two cells of some-

--.S.

Fig. 49. — Porella Bolanderi. A, Female plant, X4;
^, archegonial branches; B, an open sporogo-

Ill

THE JUNGERMANNIALES

103

what unequal size. The next wall formed divides the larger
of the two primary cells into an inner and an outer cell (Fig.
50, A), so that the young segment now consists of three cells,
an inner one and two outer ; the latter in the dorsal segments
correspond to the two lobes usually found in the dorsal leaves.
The two outer cells now divide by walls in two planes, and
rapidly grow out above the level of the apical cell and form

Fig. so. — Porella Bolanderi. A, Median longitudinal section of a vegetative axis;
B, a cross-section of the apex of a similar one, X500; x, the apical cell; h, hair;
d, dorsal surface; v, ventral surface; C. male; D, female branch.

lamellae which remain single-layered, and undergo but little
further modification beyond an increase in size. From the
base of the young leaves simple hairs develop, but remain small
and inconspicuous. The inner of the three first formed cells
of the segment, by further division and growth in all direc-
tions, produces the axis of the plant. This in cross or longi-
tudinal section shows almost perfectly uniform tissue. No
distinct epidermis, or central strand, like that found in most
Mosses, can be seen.

I04

MOSSES AND FERNS

CHAP.

The branching is monopodial and the branch represents
the ventral lobe of a leaf. After the first division by which
the two lobes of the leaf are separated, only the dorsal one
develops into the lamina of the leaf, which is thus in the seg-
ment from which a branch is to form, only one-lobed. Tn the
ventral cell three walls arise (Fig. 51), intersecting so as to
cut out a pyramidal cell of the same form as the apical cell of
the main axis, and the cell so formed at once begins to divide

Fig. 51. — Diagram showing the ordinary method of branching in the acrogynous Jun-
germanniacese (after Leitgeb). D, Dorsal; V, ventral side of stem; X' X", apical
cells of the branches. The segments are numbered.

in the same way, and forms a lateral axis of precisely the same
structure as the main one.

The genus Physiotiiim differs from all other known Acrog-
ynae in having a two-sided apical cell, instead of the typical
tetrahedral one — (Goebel (21), p. 287).

The Sex-organs

The plants in Porella are strictly dioecious and the two sexes
are at once recognisable. The males are smaller, and bear
special lateral branches which project nearly at right angles
from the main axis, and whose closely imbricated light greeii

THE JUNGERMANNIALES

105

leaver make them conspicuous. i\t the base of each of the
leaves is a long-stalked antheridium, large enough to be readily
seen with the naked eye.

The development of the antheridium may be easily traced
by means of sections made parallel to the surface of the branch.
At the apex (Fig 50, C) is an apical cell much like that in the
sterile branches, but with the outer face more convex. The
divisions in the segments are the same as there, but the whole
branch remains more slender, and the hairs at the base of the
leaves are absent. The antheridia arise singly from the bases

Fig. 52. — Porella Bolanderi. Successive stages of the young antheridium in median

longitudinal section, X6oo.

of the leaves, close to where they join the stem, and are recog-
nisable in the fourth or fifth youngest leaf (Fig. 50, C, <^).
The antheridial cell assumes a papillate form, and divides by
a transverse wall into an outer and inner cell, and the former
divides by a similar wall into two cells, of which the upper one
is the mother cell of the antheridium, and the other the stalk.
The first wall in the antheridium itself is vertical (Fig. 52, B),
and divides it into two equal parts. Each of these is now
divided by two other intersecting walls, best seen in cross-sec-

io6

MOSSES AND FERNS

CHAP.

tion (Fig. 53, A), which separate a central cell, nearly tetra-
hedral in form, from two outer cells. In the complete separa-
tion of the central cell by these first two walls, Porclla appears
to differ from the other Jungermanniace?e examined, (Leitgeb
(7), ii., p. 44), where these first two peripheral cells do not
reach to the top of the antheridium, and a third cell is cut off
before the separation of the central part of the antheridium
from the wall is complete. It is possible, too, that in Porella
this may be sometimes the case. The antheridium in cross-
section at this stage shows two perfectly symmetrical halves

( 1 .

Fig. S3. — Porella Bolanderi. A. B. Cross-sections of young antheridia, X600;
C, longitudinal section of nearly ripe antheridium, Xioo; D, ripe antheridium in
the act of opening, X50; E, F, spermatozoids, X1200.

(Fig. 53, A). The two central cells form a rhomboid sur-
rounded by six cells, the first of the primary peripheral cells
being in each case divided into two. Tlie divisions proceed
rapidly in both the central cells and in the peripheral ones. In
the latter they are for a long time always radial, so that the wall
remains but one cell thick ; but as the antlieridium approaches
maturity periclinal walls also form in the lower part, which
thus becomes double, and at places even three cells thick.
After the division of each primary central cell into equal

Ill THE JUNGERMANNIALES 107

quadrants, a series of curved walls intersecting the inner walls
of the peripheral cells arise, and then periclinal walls (Fig.
53, B), but beyond this no definite succession of walls could be
traced.

The development of the spermatozoids is the same as in
other Liverworts. The slender body shows about two com-
plete coils; the vesicle is small, but always present, and the
cilia somewhat longer than the body (Fig. 53, F). The stalk
of the antheridium is long and at maturity composed of two
rows of cells. Before the central cells of the antheridium are
separated from the peripheral ones, the stalk shows a division
into tw^o tiers of two cells each (Fig. 52, B), but it is only the
lower one that forms the real stalk ; the other forms the base
of the antheridium itself. The cells of the walls have numer-
ous chloroplasts, but the great mass of colourless sperm cell?
within make the ripe antheridium look almost pure white. If
one of these is brought into water it soon opens in a very char-
acteristic way. The cells of the wall absorb water with great
avidity, and finally the upper part bursts open by a number of
irregular lobes which curl back so strongly that many of the
marginal cells become completely detached. The whole mass
of sperm cells, with the included spermatozoids, is forced out
into the water, and if they are perfectly mature, the spermato-
zoids are quickly Hberated and swim away (Fig. 53, D.)

The female plants are decidedly larger, than the males, but
the archegonial branches are much less conspicuous than the
antheridial ones. The older ones, which either contain a
young sporgonium or abortive archegonia, are readily distin-
guished on account of the large perianth (Fig. 49, A), but
those that contain the young archegonia are situated very near
the apex of the main shoot, and are scarcely to be distinguished
from the very young vegetative branches. However, a plant
with the older perichsetia, or very young sporogonia, will usu-
ally show young archegonial branches as well.

The archegonial branch originates in the same w^ay as the
vegative branches, and the first divisions of its apical cell are
the seme ; but only two or three segments develop leaves, after
which each young segment divides into an inner and an outer
cell; the latter becomes at once the mother cell of the young
archegonium. The inner cell divides further by a transverse
wall, and the outer of the two cells thus formed gives rise to

io8

MOSSES AND FERNS

CHAP.

the short but evident pedicel of the archegonium. The latter
is very like that of the anacrogynous Liverworts. Of the three
first walls (Fig. 54, C), the last formed one is much shorter,
so that one of the three peripheral cells is much smaller, and
does not divide by a vertical wall and the neck has but five
rows of cells, as in Pcllia. This appears to be universal
among the acrogynous Jungermanniales examined. Often in
Porella the three primary walls converge at the bottom so as
to almost meet, in which case the central row of cells is nar-
rower at the base (Fig. 54, D). The rest of the development

Fig. 54. — Porella Bolandcri. Development of the archegonium. X6oo; C, cross-section
of young archegonium; G, cross-section of the neck of an older one. The others
are longitudinal sections; b, ventral canal cell; o, the egg.

is exactly as in the other Hepatic^e. The number of neck
canal cells in the full-grown archegonium is normally eight.
The archegonium (Fig. 54, F), at maturity is nearly cylin-
drical, with the venter but little enlarged. The canal cells are
broad, but the Q^g small. The venter has a two-layered wall.
The first-formed archegonia arise in strictly acropetal sue-

Ill

THE JUNGERMANNIALES

109

cession, and finally the apical cell divides by a transverse wall,
and the outer cell so formed becomes transformed into an
archegonium. In a numljer of cases observed, young arche-
gonia were noticed among the older ones, apparently formed
secondarily from superficial cells between them, and not from
the younger segments of the apical cells.

A perianth is formed about the group of archegonia, much
as in the anacrogynous forms.

Gayet ( i ) has asserted that in the Liverworts, as well as
in the true Mosses, the growth of the archegonium is largely
apical. This point has been examined again by the writer
(Campbell (21)), but Gayet's conclusions were not verified.

Fig. 55. — Porella Bolanderi. Development of the embryo. A-D, in longitudinal sec-
tion; E-G, transverse sections. B and C are sections of the same embryo, and
E, F, G are successive sections of a single embryo, X525.

The Sporophyte

The early divisions in the embryo of Porella are less regu-
lar than those in some others of ^the foliose Liverworts. The
embryo at first is composed of a row of cells, of which the
lowest, cut off by the first transverse wall, undergoes here no
further development. Li Jungennannia bienspidata (Hof-
meister, Kienitz-Gerloff, Leitgeb) this lower cell undergoes
further divisions to form the filamentous appendage at the base
of the sporogonium. The next divisions in the upper part of
the embryo correspond closely to those described in Pellia and
Anenra, but the succession of the walls is more variable and

MOSSES AND FERNS

CHAP.

the limits of the primary cells more difficult to follow. The
number of the cells, too, that contribute to the formation of
the capsule, cannot be determined exactly, and there is evi-

FiG. s6.—Porclla Bolandcri. A, Nearly median longitudinal section of an advanced
embryo, X260; B, the upper part of a similar embryo, XS25; C, sporogenous cells
and elaters from a still older sporogonium, X52 5-

dently some variation in this respect, as there is in the time of
the separation of the capsule wall from the archesporium.

Ill

THE JUNGERMANNIALES m

Both longitudinal and transverse sections of the sporogonium
at this stage (Fig. 55, D) show a good deal of irregularity in
the arrangement of the cells, and the first periclinal walls form
at very different distances from the surface, so that it is clear
that the wall cannot be established, as in Radiila for instance,
by the first periclinals.

The cells of the older archesporium are arranged in more
or less evident rows radiating from the base (Fig. 56, A).
No definite relation of spores and elaters can be made out, the
two sorts of cells being mingled apparently without any regu-
lar order. Some of the cells cease dividing and grow regu-
larly in all directions, while others may divide further and
grow mainly in the plane of division, so that they become
elongated. The former are the young spore mother cells, the
latter the elaters (Fig. 56, C). The division of the spores
begins while the cells of the archesporium are still united,
although at this time the swollen and strongly striated cell
walls of the mother cells (Fig. 56, C) show that they are be-
coming mucilaginous. At this stage sections through the
archesporium show the deeply-lobed spore mother cells with
the elongated elaters packed in between them, the pointed ends
of the latter fitting into the interstices between the spore
mother cells. The latter are somewhat angular and the wall
distinctly striated. It is the inner layer only of the wall that
projects into the cavity of the cell and forms the characteristic
lobes marking the position of the four spores. The cell cavity
is filled with crow^ded granules, some of wdiich are chloroplasts.
The nucleus, which is of moderate size, and rich in chromatin,
has a distinct nucleolus. The elaters have thinner walls than
the spore mother cells, and the contents are more finely granu-
lar. A distinct nucleus staining strongly with the usual
reagents is present. The further history of spores and elaters
corresponds closely with that of ^the forms already described.
The ripe spores have only a thin wall, which is coloured brown,
and has delicate granular thickenings.

In a paper by Le Clerc du Sablon (3) the statement is
made, and figures are given, showing that at an early stage in
the development of the spores and elaters of a number of He-
paticse the walls of the cells are completely destroyed, so that
the young spore mother cells and elaters are primordial cells.
A great many carefully stained microtome sections of a large

112

MOSSES AND FERNS

CHAP.

number of Liverworts belonging to all tbe principal groups
have been examined by me, and invariably the presence of a
definite cell wall could be demonstrated at all stages.

Many of the foliose Hepaticae show much greater regu-
larity in the early divisions of the embryo, and in the establish-
ment of the archesporium and the arrangement of its cells.
This is especially marked in Fnilhuiia (Leitgeb (7), II.)-

Here, after the upper part of
the embryo has divided into
three tiers of cells, these under-
go the usual quadrant divi-
sions, and the four terminal
cells only, form the capsule, in
which the archesporium is es-
tablished by the first periclinal
walls (Fig. 58). The divi-
sions in the archesporium are
also extremely regular, so that
the spores and elaters form
regularly alternating vertical
rows. In Fnillania the lower
cell of the embryo, instead of
remaining undivided, or form-
ing simply a row of cells, di-
vides repeatedly, and the cells
grow out into papilLx, so that
it probably is functional as an
absorbent organ, like the foot
of the Anthocerotes. Radula
(Hofmeister (i)) ^Lwd Jiingcr-
mannia, while more regular in
the divisions than Porclla, still

Fig. 57. — Porclla Bolandcri. Longi- ... ,

tudinai section of a sporogonium after are Icss SO than Fnillania, and

the final division of the archesporial jj-j tllCSC UlOrC than the Upper

^^ ^' ^ ^' tier of cells take part in the

growth of the capsule. The degree to which the seta and
foot are developed varies. In Porclla there is not a distinctly
marked foot, the lower part of the seta being simply somewhat
enlarged, but in others, like Jiuigcnnannia biciispidata, there
is a large heart-shaped foot, very distinct from the seta. In
Porclla the seta is short, projecting but little beyond the

ill

inn JUNGERMANNIALES

lt3

perianth ; but in others it may reach a length of several centi-
metres.

The development of the perianth is quite independent of
fertilisation, and not infrequently it contains, although fully
developed, only abortive archegonia. It is not always formed,
but when present, according to Leitgeb, it is the product of the
older segments of the apical cell from which archegonia are
formed, and arises as a sort of wall about the whole group of
archegonia. In Porella, as well as most of the foliose He-
patic^, the capsule opens by four equal valves, the lines of
splitting corresponding, according to Leitgeb, to the first
quadrant walls in the young embryo.

The germination of the spores shows a great deal of varia-
tion, and has been studied in a large number of forms by
several observers. Recently a number of tropical species have

Fig. 58. — Frullania dilatata. Development of the embryo, X300 (after Leitgeb); x, x,
the archesporial cells. The numbers indicate the primary transverse divisions.

been investigated, especially by Spruce (2) and Goebel (12),
and some extremely interesting variations have been discov-
ered. In these forms and when the exospore is not strongly
developed, it is simply stretched by the expanding endospore,
and finally becomes no longer discernible ; but when it is clearly
differentiated, it splits with the swelling of the endospore and
then remains unchanged at the base of the young plant. The
germinating spore may give rise to a cell mass immediately,
which develops insensibly into the leafy axis, or it may form a
simple or branched protonema of very different form, which
sometimes reaches a large size and upon which the leafy axis
arises as a bud.

The simplest form may be illustrated by Lophocolea, in
which the germinating spore divides by a transverse wall into
two equal cells, one of which continues to grow and divide
8

114

MOSSES AND FERNS

CHAP.

until a short filament is formed. After a varying number of
transverse divisions an oblique wall is formed in the terminal
cell, and a second one nearly at right angles to it. By these
divisions the dorsiventral character is established, the first-
formed segment being ventral. A third oblique wall now
arises, intersecting both of the others, and the three include a
tetrahedral cell which is the permanent apical cell of the young
plant. The ventral segments do not at first form any trace of
leaf-like structures, and in the dorsal segments the leaves are at
first simple rows of cells; but a little later the leaves show
plainly their two-lobed character, each being made up of two
rows of cells united at the base. From the ventral segments
the amphigastria develop gradually, being quite absent in the
earlier ones. CJiiloscypJins closely resembles Lophocolca, but

Fig. 59. — A, Germination of Lejeiinia serpyllifolia; B, young plant of Radula com-
planata; x, the optical cell (all the figures after Goebel).

the filamentous protonema is longer, and is often branched. A
similar filamentous protonema is present in Ccphalozia (Jiin-
gcrmannia) bicuspidafa and other species.

Lejcunia (Goebel (13) ) shows a most striking resem-
blance in its early stages to the simi)le tliallose Jungerman-
niacese. The germinating spore forms either a short filament
or a cell surface (Fig. 59, A). In either case, at a very early
stage, a two-sided apical cell is established, and for a time the
young plant has all the appearance of a young Metzgeria or
Aneura. This two-sided apical cell gives place to the three-
sided one found in the older gametophyte, and the leaves and
stem are gradually developed as in Lophocolca.

In Radula (Hofmeister (i), p. 55), and according to

Ill

THE JUNGERMANNIALES

115

Goebel, much the same condition occurs in PorcUa, the first
divisions of the spore give rise to a disc, and the formation of
a filament is completely suppressed. This disc is nearly circu-
lar in outline, and at its edge a single large cell appears (Fig.
59, B), whose relation to the primary divisions of the spore is
not quite clear. This cell forms the starting-point for the

Fig. 60. — A, Lejeunia metzgeriopsis, showing the thalloid protonema with terminal
leafy buds (&), X14 (after Goebel). B, Gemma of Cololejeunia Goebelii.

growing apex of the gametophore. As in the other forms, the
first leaves are extremely rudimentary, and only gradually is
the complete gametophyte developed.

How far this variation in the form of the protonema is of
morphological importance is a question, as the same species
may show both a filamentous protonema and the discoid form.

ii6 MOSSES AND FERNS chap.

According to Leitgeb this is the case in several species of
Jnngcnnannia, and he suggests that the conditions under which
germination takes place probably affect to a considerable extent
the form of the protonema. This is well known to be the case

in Ferns.

The very peculiar modifications observed in certain tropical
HepaticcT, especially by Spruce and Goebel, should be men-
tioned in this connection. In these forms the protonema is
permanent and the leafy gametophore only an appendage to it.
In Protoccphalo::ia cphcnicroidcs, a species discovered by
Spruce in A'enezuela, the plant forms a dense branching fila-
mentous protonema much like that of the true Mosses, which it
further resembles by having a sul^terranean and an aerial por-
tion. Upon this confervoid protonema are borne the leafy
gametophores, which are small and appear simply as buds.
Among the other remarkable forms is Lcjiinia mctzgcriopsis, a
Javanese species discovered by Goebel growing upon the leaves
of various epiphytic Ferns. It has a thallus much like that of
Mctzcgcria, and like it has a two-sided apical cell. This thallus
branches extensively (Fig. 60, A), and propagates itself by
numerous multicellular gemmse. This thallose condition is,
however, only maintained during its vegetative existence.
Previous to the formation of the sexual organs, the two-sided
apical cell of a branch becomes three-sided, as in the young
plant of other species of Lcjcuuia, and from this three-sided
apical cell a short leafy branch, bearing the sexual organs, is
produced.^

Consideral:ile variety is exhibited by the leaves of the
Acrogyucx as to their form and position, but all agree in their
essential structure and early growth. The two lobes may be
either equal in size or unequal. In the latter case either
the dorsal or ventral lobe may be the larger, when the leaves
are overlapping, as occurs in most genera. \Miere the dorsal
half is the larger it covers the ventral lobe of the leaf in front
of it, and the leaves are said to be "incubous" ; where the
reverse is the case, the leaves are "succubous." These differ-
ences are of some importance in classification.

In many species, especially the tropical epiphytic forms, one

lobe of the leaf frequently forms a sac-like organ, which ap-

* For a complete account of these forms as well as others, see Goebel's
papers in the Annals of the Buitcncorg Botanical Garden, vols. vii. and ix.,
and in Flora, 1889 and 1893

Ill

THE JUNGERMANNIALES

117

pears to serve as a reservoir for moisture. These tul3ular
structures sometimes have the opening provided with valves,
which open readily inward, but not from the inside, and thus
securely entrap small insects and crustaceans which find their
way into them. Schiffner ( ( i ) , p. 65) compares them to the
pitchers of a Sarracenia or Darlingtonia, and suggests that
they may serve the same purpose.

The branching of the foliose Jungermanniacere has been
carefully investigated by Leitgeb, and will briefly be stated
here. Two distinct forms are present, terminal branching
and intercalary. The former
has already been referred to,
but it shows some variations
that may be noted. In most
cases the whole of the ventral
part of a segment, which or-
dinarily would produce the
ventral lobe of a leaf, forms
the rudiment of the branch,
so that the leaf, in whose axil
the branch stands, has only
the dorsal lobe developed. In
the other case, only a part of
the cell is devoted to forming
the branch, and the rest forms
a diminished but evident

ventral leaf-lobe in whose ^'^- (>^--Mastigohryumtrilohatum. Longi-
Ventrai leai-lOOe, m \\nObe tudinal section of the stem, showing

axil the young branch is situ- .the endogenous origin of the branches;

, ^ rr-i r ^- r .1 ;r, the apical cell of the branch, X245

ated. ihe formation ot the ^^^^^^ Leitgeb).
intercalary branches, which

are for the most part of endogenous origin, may be illustrated
by Mastigobryuiii, where the characteristic flagellate branches
arise in this manner. The apical cell of the future branch
(the branches in this case arise in strictly acropetal order)
springs from the ventral segment, and exactly in the middle.
It is distinguished by its large size, and is covered by a single
layer of cells (Fig. 6i). In this cell the first divisions estab-
lish the apical cell, which then grows in the usual way. The
young bud early separates at the apex from the overlying cells,
which rapidly grow, and form a dome-shaped sheath, between

ii8

MOSSES AND FERNS

CHAP.

which and the bud there is a space of some size. Later the
young branch grows more rapidly than the sheath and breaks
through it.

The non-sexual reproduction of the acrogynous Hepaticae
may be brought about either by the separation of ordinary
branches through the dying away of the older parts of the
stem, or in a few cases observed (Schiffner (i), p. 67) new
plants may arise directly from almost any point of a leaf or

stem. Gemmae are known in a
large number of species. These
in most of the better known
cases are very simple unicellular
or bicellular buds arising often
in great numbers, especially
from the margins and apices of
leaves. Curious discoid multi-
cellular gemmae have been dis-
covered in a number of species,
especially in several tropical ones
investigated by Goebel (16).
Gemmae upon the thallus of Le-
jeunia mctzgcriopsis are of this
character, and similar ones are
found in CoJolcjeimia GochcUi.
In the latter (Fig. 60, B) the
gemma is a nearly circular cell
plate attached to the surface of

Fig. 62. — A, Lcjemiia sp., showing the ,1 i r i .11 1 r

ventral leaves, or amphigastria. am the Icaf by E Stalk COUipOSCd of

(X about 40). B, a West Indian a siuglc CCll. The first Wall iu
Leieunia, the lower leaf-lobes. X, , 1 ^• ' ^ ' j.

modified as water-sacs (X75). ^}^^ ^^^^^^ gCmUia dlVldcS it

into two nearly equal cells, in
each of which a two-sided apical cell is formed, so that like the
gemma of Marchantia there are two growing points. There
are usually four cells that differ from the others in their thicker
walls and projecting on either side of the gemma above the
level of the other cells. These serve as organs of attachment,
perhaps by the secretion of mucilage, and by them the young
plant adheres to the surface of the fern leaf upon which it
grows. The development of the gemmae, whether unicellular
or multicellular, resembles very closely that of the germinating
spores.

Ill

THE JUNGERMANNIALES

119

Representatives of the Acrogynse are found in all parts of
the world, and many of the larger genera are cosmopolitan.
It is in the wet mountain forests of tropical and subtropical
regions that they reach their greatest development, both as
to size and numbers. In these regions they replace to a great
extent the Mosses of the more northern forests. Some of
them are extremely minute, and grow as epiphytes upon the
leaves and twigs of trees and shrubs, or even upon the leaves
of ferns, or of larger Liverworts. Some of the larger forms,
like species of Bazzania or Schistochila (Fig. 63) are conspicu-
ous and characteristic plants.

Classification of the Acrogynce

In attempting to subdivide
this very large family, numer-
ous difficulties are encountered.
Their affinity with the Ana-
crogynse is unmistakable, but it
is highly improbable that the
family, as a whole, has had a
common origin. It is much
more likely that different types
of leafy Liverworts have origi-
nated quite independently from
different anacrogynous proto-

FiG. es.-schistockiia Ippendicuiata. A. typcs. While thc Acrogyuae
plant of the natural size; B, two sliow a good deal of Variation,

dorsal and one ventral leaf (v), X.. ^^^ differences are UOt COUStaut,

and the different groups or sub-families merge so into each
other as to make a satisfactory division of the family almost
hopeless. According to Schiffner ( i ) , the only one of the sub-
families which he recognizes, which is clearly delimited, is
the Jubuloidese. He recognizes the following sub-families
(Schiffner (i), p. 74) :

I, Epigonianthese; ILTrigonanthese; III, Ptilidioideae ;
IV, Scapanioide^e ; V, Stepaninoidese ; VI, Pleurozioideae ;
VII, Bellincinioide^; VIII, Jubuloideae.

CHAPTER TV

THE ANTHOCEROTES

Tins group contains but three genera, AnfJioccros, Dcndro-
ccros, and Notothylas, and differs in so many essential particu-
lars from the other HepaticcX that it may be questioned whether
it should not be taken out of the Hepatic?e entirely and given
a place intermediate between them and the Pteridophytes. All
the members of the class correspond closely in the structure
of the gametophyte, and while showing a considerable varia-
tion in the complexity of the sporophyte, there is a perfect series
from the lowest to the highest in regard to the degree of de-
velopment of the latter, so that the limits of the genera, are
sometimes difficult to determine. The Anthocerotes are of
extraordinary interest morphologically, as they connect the
lower Hepaticse on the one hand with the Mosses, and on the
other with the vascular plants. Leitgeb ( (7), v., p. 9) has en-
deavoured to show that they are sufficiently near to the Jun-
germanniales to warrant placing them in a series with that
order opposed to the Alarchantiales, but a careful study of
both the gametophyte and the sporophyte has convinced me
that this view cannot be maintained; and that while probably
the affinities of the Anthocerotes are with the anacrogynous
Jungermanniales rather than with the IMarcliantiales, never-
theless the two latter orders are much nearer each other than
the former is to either of them.

The gametophyte in all the forms is a very simple thallus,
either with or withcxit a definite midrib. Of the three genera
Dcndroceros is confined to the tropical regions, while the other
genera occur in the temperate zones, but are more abundant in
the warmer regions, where they also reach a greater size. The

species of Anthoceros and Notothylas grow principally upon

120

IV.

THE ANTHOCEROTES 121

the ground in shady and moist places, and are usually not
well adapted to resist dryness.

The chloroplasts in the Anthocerotace?c resemble those in
certain confervoid Algas, e. g., Stigeoclonium, Colcochccte.
Each cell in most species shows a single large chloroplast con-
taining a pyrenoid. In sterile specimens of an undetermined
species of Anthoccros from Jamaica, two chloroplasts were
found in each cell, and a doubling of the chloroplast is not un-
common in the more elongated thallus-cells of other species,
while in the sporophyte there seem to be regularly two chloro-
plasts in each cell. Simple thin-walled rhizoids are formed
abundantly upon the ventral surface, where there are in many
species curious stoma-like clefts which open into cavities filled
with a mucilaginous secretion, and in some of which, in all
species yet examined, are found colonies of Nostoc which form
dark blue-green roundish masses, often large enough to be
readily detected with the naked eye, and which were formerly
(Hofmeister (i), p. 18) supposed to be gemmae.

The sexual organs are very different from those of the
true Hepaticae, and are more or less completely sunk in the
thallus from the first. While the first divisions in the
archegonium are much like those in the HepatiCcX, the subse-
quent ones are much less regular except in the axial row of
cells, and the limits of the outer neck-cells are in the subsequent
stages difficult to determine, and the archegonium projects
very little above the surface of the thallus, even when full
grown. The divisions in the axial row of cells correspond to
those in the other Archegoniatse.

The origin of the antheridium is entirely different from
that of all other Bryophytes, but shows, as will be seen later,
certain suggestive resemblances to that of the lower Pteri-
dophytes. Instead of arising from a superficial cell, as in all
of the former, the antheridium, or in most cases the group of
antheridia, is formed from the inner of two cells arising by the
division of a superficial one. The outer one takes no part in
the formation of the antheridia, but simply constitutes part of
the outer wall of the cavity in which they develop.

While the gametophyte is extremely simple in structure,
being no more complicated than that of Aneiira or Metsgeria,
the sporophyte reaches a high degree of complexity. Here,
instead of the greater part of the sporophyte being devoted to

122 MOSSES AND FERNS chap.

Spore formation, and dying as soon as the spores are scattered,
the archesporium, especially in the higher forms, constitutes
but a small part of the sporogonium, which develops a highly
differentiated system of assimilating tissue, with complete
stomata of the same type as those found in vascular plants;
and in addition a central columella is present whose origin and
structure point to it as possibly a rudimentary vascular bundle.
In all of them this growth of the sporophyte is not concluded
with the ripening of the first spores, but for a longer or shorter
time it continues to grow and produce new spores. This reaches
its maximum in some species of Anthoccros, where the sporogo-
nium may reach a length of several centimetres, and continues
to grow as long as the gametophyte remains alive. In these
forms the foot is provided with root-like processes, which are
closely connected with the cells of the gametophyte, from
which nourishment is supplied to the growing sporophyte.

The archesporium produces spores and elaters, but the
latter are not so perfect as in most of the Hepatic?e. They
often show a definite position with regard to the spore mother
cells; this is especially marked in Notothylas. The arche-
sporium in all forms that have been completely investigated
arises secondarily from the outer cells of the capsule. Leitgeb's
( (?)» V- P- 49) conjecture that in NotofJiylas the whole central
part of the capsule is to be looked upon as the archesporium, is
not confirmed by my observations on N. valvata ( orbicular is ) ,
where the formation of a columella and the secondary develop-
ment of the archesporium are exactly as in Anthoccros} It is
hardly likely that in the other species there should be so essen-
tial a difference as would be implied by such an assumption.
The development of the spores and their germination show
some peculiarities which will be considered when treating of
these specially. The sporogonium shows no clear separation
into seta and capsule, all except the foot and a very narrow
zone above it producing spores. At maturity it opens longi-
tudinally by two equal valves, between which the columella
persists. The splitting is gradual and progresses with the
ripening of the spores.

The genus Anthoceros includes about twenty species,
widely distributed, but most abundant in the warmer parts of

* See also Mottier (2).

IV.

THE ANTHOCEROTES 123

the world. The species that lias been most frequently studied
is A. Icrvis. The related A. Pcarsoni has been carefully in-
vestigated by the writer, and also the larger A. fiisiformis, a
common Calif ornian species allied to A. ptinctatiis.

The gametophyte in all species is a dark green or yellowish
green fleshy thallus, branching dichotomously so that it may
form orbicular discs not unlike those of the Marchantiaceae in
shape; but owing to the rapid division of the growing point,
and the irregular margin of the thallus, the separate growing
points are not readily made out. The surface of the thallus
may be smooth asm A. lcEvis,ox much roughened, with ridges
and spines as in A. fiisiforinis. The thallus may be quite com-
pact, or there may be large intercellular spaces or chambers.
The latter are not filled with air, as in the similar chambers of
the Marchantiaceae, but with a soft mucilage. Here and there,
imbedded in the thallus, are small dark blue-green specks,
which a closer examination shows to be colonies of Nostoc,
which are invariably found in the thallus. Colourless rhizoids
fasten the thallus to the ground. Sometimes the yellowish
antheridia can be detected with the naked eye, but there is no
indication visible of the archegonia, which are very inconspic-
uous and completely sunk in the thallus, and their presence can
only be detected by sectioning.

The sporophytes are relatively large and may be produced
in great numbers, this being especially conspicuous in A.
fusiforiiiis, where they may reach a length of six or seven
centimetres, and stand so close together that a patch of fruit-
ing plants looks like a tuft of fine grass.

Both of the common Californian species, A. Pearsoni and
A. fusiformis are perennial. The growing point of the shoot,
with a certain amount of the adjacent tissue, remains alive and
persists through the summer, after the rest of the plant has
dried up. Probably the great ^amount of mucilage in the
thallus helps to check the loss of water, and enables the plant
to survive the long summer drought.

Growth begins promptly with the first autumn rains, and
by mid-winter, or sometimes earlier, the reproductive organs
mature. The sporophyte continues to grow in length as long
as the thallus receives the necessary moisture. New sporog-
enous tissues develops at the base of the sporophyte long after
the first spores have been shed. With the cessation of its

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IV.

THE ANTHOCEROTES 125

water-supply through the drying up of the thallus, the sporo-
phyte finahy dies.

' In order to study the apical growth satisfactorily, young
plants that show no signs of the sporogonia should be selected.
In A. fusifoniiis such a plant will show the margin of the
thallus occupied by numerous growing points separated by a
greater or smaller number of intervening cells. It is some-
what difficult to determine positively whether one or more
apical cells are present. In sections parallel to the surface the
initial cells are seen to occupy the bottom of a shallow depres-
sion (Fig. 65, C). In the case figured, x probably is the single
apical cell, and it seems likely that this is usually the case, al-
though Leitgeb was inclined to think that there w^ere several
marginal cells of equal rank. The outer w^all of the cells
shows a very marked cuticle. A vertical section passing
through one of the growing points (Fig. 66) shows that the
apical cell is much larger than appears from the horizontal
section. On comparing the two sections it is evident that its
form is the same as in the ]\Iarchantiace?e or Pallavicinia. Two
sets of lateral segments, and two sets of inner ones, alternately
ventral and dorsal, are cut off, and the further divisions of
these show^ great regularity, this being especially the case in
the dorsal and ventral segments. Each of these first divides
into an inner and an outer cell. The former divides repeatedly
and in both segments forms the central part of the thallus. It
is these cells that, according to Leitgeb, later show thickenings
upon their w^alls somewhat like those met with in many Mar-
chantiace^. From the outer cells are developed the special
superficial organs both on the ventral and dorsal sides. From
the former arise the colourless delicate rhizoids and peculiar
stoma-like organs, the mucilage clefts, first described by
Janczewski ( i ) , who also pointed out the true nature of the
Nostoc colonies found within the thallus. These mucilage
clefts, especially in their earlier stages, resemble closely the
stomata of the higher plants. They arise by the partial sep-
aration of two adjacent surface cells close to the growing
point, and often at least, the two cells bounding the cleft are
sister cells. However, the same division of the neighboring
cells frequently occurs without the formation of a cleft, and
there is nothing to distinguish the two cells bounding the cleft
from the adjacent ones, and a homology with the real stomata

126

MOSSES AND FERNS

CHAP.

on the sporogonia is not to be assumed. The mucilage sht
becomes wider, and beneath it an intercehular space is formed
which widens into a cavity whose cells secrete the abundant

Fig. 65. — AntJioccros fusifonnis. A, Young plant with single growing point (.r), X85;
B, horizontal section of the growing point of a similar plant, Xs^s; x, the single
apical cell; C, similar section of a growing point from an older plant, with pos-
sibly more than one initial cell, X260; D, a mucilage slit from the ventral side of
the thallus, X525.

mucilage filling it. This mucilage escapes through the clefts
and covers the growing point in the same way as that secreted
by the glandular hairs in the Jungermanniacese.

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128 MOSSES AND FERNS chap.

Each cell of the thallus contains a single chloroplast which
may be either globular or spindle-shaped, or more or less
flattened. The nucleus of the cell lies in close contact with
the chloroplast, and usually partly or completely surrounded
by it. There is no separation of the tissues into assimilative
and chlorophylless, as in the Marchantiacese, and in this respect
Anthoccros approaches the simplest Jungermanniacea?, as it
does in the complete absence of ventral scales or appendages
of any kind, except the rhizoids.

The infection of the plant with the Nostoc has been care-
fully studied by Janczewski and Leitgeb ( (7), v., p. 15). The
infection takes place while the plant is young, and is usually
brought about by a free active filament of Nostoc making its
way into the intercellular space below the mucilage slit, through
whose opening it creeps. Once established, the filament
quickly multiplies until it forms a globular colony. The
presence of the parasite causes an increased growth in the cells
about the cavity in which it lies, and these cells grow out into
tubular filaments which ramify through the mass of filaments,
and becomes so interwoven and grown together that sections
through the mass present the appearance of a loose par-
enchyma, with the Nostoc filaments occupying the interstices.
Other organisms, especially diatoms and OsciUarccc, often
make their way into the slime cavities, but according to Leit-
geb's investigations their presence has no effect upon the
growth of the thallus.

Sexual Organs.

The plants are monoecious in A. fusiformis, and this is
true of other species observed. In the former, however, the
antheridia appear a good deal earlier than the archegonia. I
o])served them first on young plants grown from the spores,
that were not more than 3 mm. in length. The exact origin
of the cell which the antheridia develops could not be made
out, as none of my sections showed the youngest stages.
Waldner's (2) observations upon A. larris, however, and my
own on A. Pcarsoni and Notothylas valvata, as well as a study
of the older stages in A. fusiformis, leave no doubt that in this
species as in the others the antheridia are endogenous, and the
whole group of them can be traced back to a single cell. They
arise close to the growing point, and the cell from which they

IV.

THE ANTHOCEROTES

129

arise is the inner of two cells formed by a transverse wall in a
surface cell. The outer cell (see Figure 67, B) divides almost
immediately by another wall parallel with the first, so that the
group of antheridia is separated by two layers of cells from
the surface of the thallus. The inner cell in A. Pearsoni at
once develops into an antheridium; but in most species the
cell divides first by a longitudinal wall into two, each of which

Fig. 67. — Anthoceros Pearsoni. Development of the antheridium: A, apex of the
thallus, with very young antheridium, X about 500; B, a somewtiat older stage;
C, still older stage, somewhat less highly magnified; D, an older, but still im-
mature antheridium, X about 200.

generally divides again, so that there are four antheridium
mother cells, all, however, unmistakably the product of a single
cell, and if a comparison is to be made with the antheridium of
any other Liverw^ort, the antheridium in the latter is homol-
ogous, not with the single one of Anthoceros, but with the
whole group, plus the two-layered upper wall of the cavity in
which they lie.

. The first divisions in the antheridium are the same as those
in the original cell, i.e., the young antheridium is divided longi-
tudinally by tw^o intersecting walls, and the separation of the
9

I30

MOSSES AND FERNS

CHAP.

stalk from the upper part is secondary ; indeed in the earhest
stages it is difficult to tell whether these longitudinal divisions
will result in four separate antheridia or are the first division
walls in a single one. Secondary antheridia arise later by
budding from the base of the older ones, so that in the more
advanced conditions the antheridial group consists of a varying
number, in very different stages of development (Fig. 68, A).

A .-w^<- /^ C,

I D.

Fig. 68. — Anthoceros fusiformis. Development of the antheridium; D, E, drawn from
living specimens, the others microtome sections; D, i, shows the single chloroplast
in each of the wall cells, and the secondary antheridium (s) budding out from
its base; 2 is an optical section of the same; E, surface view of full-grown antherid-
ium; F, cross-section of a younger one. Figs. A, E X225, the others X45o-

After the first transverse walls by which the stalk is separated,
the next division in each of the upper cells is parallel to it, so
that the bo<ly of the antheridium is composed of nearly equal
octant cells. Then by a periclinal wall each of these eight cells
is divided into an inner and an outer cell, and the eight central
ones then give rise to the sperm cells, and the outer ones to
the wall. The four stalk cells by repeated transverse divisions
form the four-rowed stalk found in the ripe antheridium. The
uppermost tier of the stalk has its cells also divided by vertical
walls and forms the l)asal part of the antheridium wall. The
transverse and vertical division walls in the central cells alter-
nate with great regularity, so that there is little displacement
of the cells, and up to the time of the separation of the sperm

IV. THE ANTHOCEROTES 131

cells the four primary divisions are still plainly discernible, and
the individual sperm cells are cubical in form. In the per-
ipheral cells hardly less regularity is observable. Except near
the apex none but radial walls are formed after the first trans-
verse wall has divided the body of the antheridium into two
tiers, and when complete the wall consists of three well-
marked transverse rows of cells, the lower being derived from
the uppermost tier of stalk cells. At the apex the cells are not
quite so regular (Figs. D, E). In its younger stages the
antheridium is very transparent and perfectly colourless. In
each peripheral cell a chloroplast is evident, but at this stage
it is quite colourless and the nucleus is very easily seen in close
contact with it. As the antheridium grows the chloroplasts
develop with it, becoming much larger and elongated in shape,
and at the same time develop chlorophyll. The mature chloro-
plast is a flattened plate that nearly covers one side of the cell,
and its colour has changed from green to a bright orange as in
the antheridium of many Mosses. The sperm cells are dis-
charged through an opening formed by the separation of the
apical cells of the antheridium. These cells do not become
detached, but return to their original position, so that the
empty antheridium has its wall apparently intact. The sperma-
tozoids are small and entirely like those of the other Hepaticse.

Leitgeb ((7), v., p. 19) found in abnormal cases that the
antheridia may arise superficially, as in the typical Hepaticae.
Lampa (i) describes a similar exogenous origin for the
antheridium, but How^e (5) has questioned the accuracy of
her statements, and thinks that the supposed antheridia were
tubers, as Frau Lampa's figiu-es do not agree with the structure
of the typical antheridium. Whether this exogenous develop-
ment of the antheridium is a reversion to a primitive condition
is impossible to decide, but it is possible that such is the case.

At first the cell from which the antheridial complex arises
is not separated from its neighbours by any space. About
the time that the first divisions in it are formed, the young
antheridial cells begin to round off and separate from the
cells above them. With the growth of the surrounding cells
this is increased, so that before the divisions in the separate
cells begin, the group of papillate cells is surrounded by a
cavity of considerable size. To judge by the readiness with
which the walls of the cavity stain, it is probable that the

132 MOSSES AND FERNS chap.

separation of the cells is accompanied by a mucilaginous
chano-e in their outer layers.

The first account of the archegonium was given by Hof-
meister, who. however, overlooked the peripheral cells and only
saw the axial row. Later Janczewski (2) showed that Antho-
ccros did not differ essentially in the development of the
archegonium from the other HepaticcC, and his observations
were confirmed Ijy the later researches of Leitgeb and Wald-
ner (2). The formation of archegonia does not begin until
the older antheridia are mature, and very often, especially in
A. Pcarsoni, few or no antheridia were found on the plants
with well-developed archegonia. After the formation begins,
each dorsal segment gives rise to an archegonium, so that they
are arranged in ciuite regular rows, in acropetal order. After
the transverse wall by which the segment is divided into an
inner and an outer cell is formed, the outer cell becomes at
once the mother cell of the archegonium, much as in Aiiciira.
In this cell next arise three vertical intersecting walls, by
which a triangular (in cross-section) cell is cut out as in the
other HepaticcT. Sometimes it looks as if one of these walls
was suppressed, but even in such cases the triangular form of
the central cell is evident. The main difference between the
archegonium at tliis stage in Anthoccros and the HepaticcX
lies in the complete submersion of the archegonium rudiment
in the former. In this respect Anciira, where the base of the
archegonium is confluent with the cells of the thallus, offers an
interesting transition between the other Hepatice, where the
base of the archegonium is entirely free, and Anthoccros.

The archegonium rudiment divides into two tiers as in the
other Liverworts, and the peripheral cells divide longitudinally,
and the neck shows the six vertical peripheral rows although
it is completely sunk. Later, the limits of the neck become
often hard to determine, although l)y later divisions the central
:ell is surrounded by a pretty definite layer of cells. The
axial cell divides into two of nearly equal size, but the inner one
soon increases in breadth more tlian the upper one. The latter
divides again by a transverse wall into an outer cell corre-
sponding to the cover cell of the ordinary he])atic archegonium,
the other to the primary neck canal cell. The cells of this cen-
tral row soon become clearly different from the other through
their more granular contents. The lower cell grows much

IV.

THE ANTHOCEROTES

133

faster than the others and divides into the tgg cell and the
ventral canal cell. The cover cell divides by a vertical wall
into two nearly equal cells, and these usually, but not always,
divide again, so that four cells arranged cross-wise form the
apex of the archegonium. In A. fiisiformis in nearly ripe
archegonia I have sometimes been able to see but two of these
cover cells, but ordinarily four are present. The neck canal
cell divides first into two, and these then divide again, so that
four cells are formed. This was the ordinary number in A.
fiisiformis. In a nearly ripe archegonium of A. Pearsoni five
neck canal cells w^ere seen, but in no cases so many as

Fig. 69. — Anthoceros fusiformis. A two-celled embryo within the archegonium venter,
X600; B, C, two longitudinal sections of a four-celled embryo, X600.

Janczewski describes for A. Iccvis, where he says as many as
twelve may be present.

If the earlier divisions in the archegonium of Anthoceros
are compared with those of the other Hepaticae, the most strik-
ing difference noticed is the separation of the cover cell. In
the latter the first division of the axial cell separates the cover
cell from an inner one, and by the division of the latter the
primary neck canal cell is cut off from the central cell. In
Anthoceros the neck canal cell is cut off from the outer, and not
from the inner cell.

134 MOSSES AND FERNS chap.

As the archegonium approaches maturity the cover cells
become very much distended and project strongly above the
surrounding cells. In stained microtome sections their walls
colour very strongly, showing that they have become partially
mucilaginous. This causes them to separate readily, and they
are finally thrown off, so that in the open archegonium no trace
of them is to be seen. The walls of the canal cells and the
central cell undergo the same mucilaginous change, but here it
is complete, and before the archegonium opens the partition
walls of the canal cells completely disappear, and the neck con-
tains a row of isolated granular masses corresponding in num-
ber to the canal cells. The ventral canal cell is quite as large
as the Qgg, which consequently does not nearly fill the cavity at
the base of the open archegonium (Fig. 66, D) after the canal
cells have been expelled. The egg did not, in any sections
studied, show clearly a definite receptive spot, but appeared to
consist of uniformly granular cytoplasm with a nucleus of
moderate size. The upper neck cells in the open archegonium
become a good deal distended, and the canal leading to the
egg is unusually wide. Surrounding the central cavity the
cells are arranged in a pretty definite layer.

Miss Lyon ((2), p. 288) states that she has frequently
found archegonia in A. Icevis, produced upon the ventral side
of the thallus.

The SporopJiyte

Hofmeister was the first to study the development of the
embryo in Anthoceros, and described and figured correctly the
first divisions, but his account of the apical growth, which he
supposed was due to a single apical cell, and the differentiation
of the archesporium, was shown by the careful investigation of
Leitgeb ((7), v.) to be erroneous. The following account
is based upon a large series of preparations of A. Pearsoni and
A. fusiform is, which seem to agree in all respects. After
fecundation the egg at once develops a cellulose wall and be-
gins to grow until it completely fills the centre cavity of the
archegonium. As it grows the uniformly granular appear-
ance of the cytoplasm disappears, and large vacuoles a're
formed, so that the whole cell appears much more transparent.
The granular cytoplasm is now mainly aggregated about the
nucleus, which has also increased in size (Fig. 66, E). The

IV. THE ANTHOCEROTES I35

first division wall is parallel with the axis of the archegonium
and divides the embryo into two equal parts, in which the
character of the cells remains much as in the undivided tgg.
Here too the granules are most abundant about the nucleus,
from which radiate plates that separate the vacuoles. The
next divisions are transverse and divide the embryo into two
upper large cells and two lower smaller ones. The embryo at
this stage is oval and more or less pointed above. In each of
the four primary cells vertical walls arise that divide the
embryo into octants, but the upper octants are decidedly larger
than the lower. Next, in the upper cells, transverse walls are
formed and the embryo then consists of three tiers of four cells
each. Of these the cells of the upper tier are decidedly the
larger. At this stage, in neither species examined by me,
were any traces present of the projection of the basal cells
figured by Leitgeb (1. c. PL I.)- As his drawings were made
from embryos that had been freed from the thallus, probably
with the aid of caustic potash, it is quite possible that this ap-
pearance was due in part at least to the swelling of the cell
walls through the action of the potash. At any rate in micro-
tome sections of both species in these early stages, the basal
cells do not project in the least (Fig. 70, A). The next di-
visions are very uniform in the upper tier of cells, from which
the capsule develops, but less so for the two lower ones. In
the upper tier, seen in cross-section (Fig. 70, B i), a slightly
curved wall running from the median wall to the periphery
forms in each quadrant, which thus viewed is divided into an
inner four-sided and outer three-sided cell. In the former a
periclinal wall next forms, which cuts off an inner square cell
(Fig. 70, D). In longitudinal section these periclinal walls
are seen to be concentric with the outer walls of the cells, and
to strike the median and quadrant walls at some distance below
the apex of the sporogonium so as to completely enclose the
central cells (Fig. 70, C). By the formation of these first
periclinal walls the separation of the columella from the wall
of the capsule is completed, and this is not unlike what obtains
in the sporogonium of many other Hepaticse ; but an essential
difference must be observed. In the latter the central group
of cells forms the archesporium ; here these cells, as we shall
see, take no part in spore formation. In the lower tiers of
cells similar but less regular divisions occur (Fig. 70, D 2),

136

MOSSES AND FERNS

CHAP.

and the outer cells begin to grow out into root-like processes
which push down among the cells of the thallus and obviously
serve the purposes of haustoria. Leitgeb states that tlie foot
arises only from the lowest of the primary tiers of cells, but in
most of my sections of the earlier stages the fact that the foot
was composed of two distinct layers of cells, corresponding in
position to the two lower tiers of cells in the embryo, was very
obvious (Fig. 70, E).

Fig. 70. — Anthoceros Pearsont. Development of the embryo X300; A, C, E, median
longitudinal sections; B and D, successive cross-sections of embryos of about the
age of A and C respectively. In E the archesporium is differentiated.

The origin of the archesporium in Anthoceros was in the
main correctly shown by Leitgeb, but I find that the extent of
the archesporium is less than he represents. In PI. I. Figs. 3
and 10 of his monograph on the AnthocerotCcX, he figures the
archesporium as extending completely to the base of the
columella. A large number of sections were examined, and
in no case was this found to be so. Instead, it was only from
the cells surrounding the upper half of the columella tliat the
archesporium was formed. Previous to the differentiation of

IV. THE ANTHOCEROTES I37

the archesporium the four primary cells of the columella divide
by a series of transverse walls until there are about four cells
in each row. Radial walls also form in the outer cells so that
their number also increases, and the young capsule consists of
the central columella composed of four rows of cells and a
single layer of cells outside. The archesporium now arises
by a series of periclinal walls in the peripheral cells of the upper
half only of the capsule, and is thus seen to arise from the
peripheral cells of the capsule, and not from the central ones.
Fig. 70, E shows a longitudinal section of the sporogonium at
this stage. Three parts may be distinguished — the foot, the
capsule, and an intermediate zone between. The latter is
important, as it is from this that the meristematic part of the
older sporogonium is formed. With the separation of the
archesporium the apical growth ceases, and the future growth
is intercalary.

In the capsule cell divisions proceed rapidly in all its parts.
The original four rows of cells forming the columella increase
to sixteen, which is the normal number in the fully-developed
sporogonium. The archesporium, by the formation of a sec-
ond series of periclinal walls, becomes two-layered, and the
wall outside the archesporium becomes about four cells thick,
the outermost layer forming a distinct and well-developed
epidermis.

The foot grows rapidly in size, but the. divisions are very
irregular, and finally it forms a large bulbous appendage to the
base of the sporogonium. The cells are large and the outer
ones develop still further the root-like character of those in
the young foot. The tissues of the thallus about the base of
the sporogonium grow rapidly with it, and the connection
between the surface cells of the sporogonium foot and the
adjacent cells of the thallus is very intimate.

The subsequent growth of the. capsule is entirely dependent
upon the activity of the zone of meristem at its base. This
divides very actively, and the divisions correspond exactly with
the primary ones in the young embryo, so that the completed
portions of the older parts of the capsule are continuous with
the forming tissues at the base. A series of cross-sections at
different points, compared with a median longitudinal section,
shows in a most instructive way the gradual development of the
different parts of the mature capsule (Fig. ^2). The centre

138

MOSSES AND FERNS

CHAP.

of the sporogonium is occupied by a columella composed of
sixteen rows of cells, which in cross-section form a nearly per-
fect square. At the base these cells are thin-walled and show
no intercellular spaces, but farther up their walls begin to
thicken and the rows gradually separate until in the upper part
the columella has somewhat the appearance of a bundle of
isolated fibres. The archesporium is constantly growing from
below, and the new cells are cut off from those surrounding the

columella in the same way as at first.
The archesporium, as well as the colu-
mella, can be traced down nearly to the
base of the capsule, and its cells are very
early recognisable both by their position
and by their contents. At first but one
cell thick, the archesporium soon be-
comes double, but does not advance be-
yond this condition. As the archespo-
rium is followed from the base towards
the apex of the capsule the cells begin
to show a differentiation. Up to the
point where the archesporium becomes
divided into two layers the cells appear
alike; but shortly after this their walls
begin to separate, and two distinct
forms are recognisable, arranged with
much regularity in many cases, although
this arrangement is not invariable.
Pretty regularly alternating are groups
of oval, swollen cells, with large nuclei
and abundant granular cytoplasm, and
much more slender ones, that may un-
dergo secondary longitudinal divisions.
The latter have smaller nuclei and more
transparent contents. Examination
higher up shows that the former are
the spore mother cells, the others the elaters, which here have
the character of groups of cells, and do not develop the spiral
thickenings found in most Hepaticc-e. As these two sorts of
cells grow older they separate completely, and the spore mother
cells become perfectly globular. The sterile cells remain more

Fig. 71. — Antjioceros Pear-
soni. Median longitudinal
section through the base
of the sporogonium. The
archesporium is shaded,
F, Foot; V, V, basal
sheath of calyptra, X 100.

IV.

THE ANTHOCEROTES 139

or less united, and form a sort of network in whose interstices
the spores He.

The development of the spores can be easily lollowed, at
least in most of the details, in fresh material, and on this
account it w^as among the first plants in which cell division was
studied. The mother cells in all stages can be found in the
same sporogonium, and on account of their great transparency
show the process of cell division very satisfactorily. The
nucleus, however, is small, and its behaviour during the cell
division is not so easy to follow. The mother cell, just before
division, is filled with colourless cell sap, and the cytoplasm is
confined to a thin film lining the cell wall. This cytoplasmic
layer is somewhat thicker on one side, and here the nucleus is
situated (Fig. 73, A). Lying close to the nucleus is a round-
ish body, of granular consistence and yellowish green in colour.
This is a chloroplast, which at this stage is less deeply col-
oured than later. The chloroplast contains a number of
granules, some of which are starch. The cell increases rapidly
in size, and the nucleus, together with the chloroplast, move
away from the wall of the cell tow^ard the centre, where they
are suspended by cytoplasmic threads. The chloroplast next
divides into two equal portions, wdiich move apart (Fig. 73,
B), but remain connected by the cytoplasmic filaments. They
approach again, and each dividing once more, the four result-
ing chloroplasts remain close together with the nucleus, in the
centre of the cell.

Davis (i) has made a very complete study of the spore
division in A. Icevis. In this species the archesporium is less
massive than in A. Pearsoni or A. fiisiformis, and the ar-
rangement of the sporogenous and sterile cells less regular.
Davis found that the sporophytic nuclei had regularly eight
chromosomes, those of the gametophyte four.

Owing to the small amount ^of chromatin in the nucleus,
the karyokinetic figures are small and the changes difficult to
follow satisfactorily. Enough can be easily made out, how*
ever, to show that the process is in no way peculiar. There is
first a nuclear spindle of the ordinary form, and the resulting
nuclei assume the resting stage before dividing again. Each
then divides, and the four nuclei move to points equi-
distant from each other, and which are already occupied by the
four chloroplasts. After this is accomplished, cell walls arise

C3 ,

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IV.

THE ANTHOCEROTES

141

simultaneously between the four nuclei dividing the mother cell
into four tetrahedral cells, — the young spores. The wall of the
mother cell becomes thicker, and in the later stages swells up
on being placed in water, so that it interferes a good deal w^th
the study of the spores in the fresh condition. As the spores
ripen they develop a thick exospore, which is yellow in colour
and irregularly thickened in A. Pcarsoni, and in A. fiisiformis
black and covered with small tubercles. The chlorophyll disap-
pears and the spore becomes filled with oil and otlier food
materials. The spores remain together until nearly ripe. The
elaters, if this name can properly be applied to the sterile cells,
at maturity consist of

simple or branching
rows of cells, wdiich in
some cases arise from
the division of a single

one ; but
monly, at
Pearsoni,
branch, it
that thev

more com-
least in A.
where they
is probable
are to be
looked upon as merely
fragments of the more
or less continuous net-
w^ork of sterile cells.
The contents mainly
disappear from the
older elaters, and their
walls become thick and

Fig. 73. — Spore division in A. fiisiformis ; optical
sections of living cells, X600.

in colour like the wall

of the spores. In A. fiisiformis they are longer and more
symmetrical than in A. Iccvis, and in one group of the genus,
according to Gottsche (2), the elaters, which consist of a row
of five to six cells, have a distinct spiral band as in Dendroceros.
Leitgeb thinks, however, that this group is more nearly related
to the latter genus than to Anthoccros proper, inasmuch as in
addition to the peculiar elaters the epidermis of the capsule has
no stomata, which are always present in typical species of
AiitJioceros.

If the epidermis from the young capsule is examined it is
seen to be composed of elongated narrow cells much like those

142

M0SSE9 AND FERNS

CHAP.

in the epidermis of elongated leaves of Monocotyledons. In
the older parts some of these cells cease to elongate, and be-
come more nearly oval (Fig. 75, A). These are the young
stomata, and exactly as in the vascular plants, each divides
longitudinally by a septum which later separates in the middle
and forms the pore surrounded by its two guard cells. The
walls of the other epidermal cells become much thickened and
distinctly striated. Each epidermal cell contains two large
chloroplasts like that in the cells of the gametophyte, and be-
tween the cells are well-developed air-chambers communicat-
ing with the stomata, so that there is here a typical assimilative
system of tissues.

The doubling of the chloroplast in the cells of the sporophyte
has been noted by Schimper (A. F. W. Schimper (2)), and

Fig. 74. — Ripe spores and elatcrs oi A. Pearsoni, X6oo.

this was observed by the writer in both A. fitsifoniiis and A.
Pearsoni.

About the base of the growing sporogonium is a thick
tubular sheath representing in part the calyptra of the other
Hepatic?e, but involving, besides the archegonium venter, also
the surrounding tissue of the gametophyte. This sheath keeps
pace with the growth of the sporophyte for a long time, but
finally the sporogonium grows more rapidly and projects far
beyond it, and this remains as a tube surrounding its base.
The growth of the sporogonium continues as long as the
gametophyte remains alive, and in A. fusiformis is often 6

IV.

THE ANTHOCEROTES

143

centimetres or more in length, and reaches nearly this length
before the first spores are ripe and the capsule opens. This it
does by splitting at the top into two equal valves between
which the dried-up columella protrudes. The split deepens as
the younger spores ripen, and may finally extend nearly to the
base. It is quite possible, although this point was not investi-
gated, that the line of dehiscence
corresponds to the primary verti-
cal wall in the embryo, as is the
case in the Jungermanniacese.

The germination of the
spores^ has hitherto been ob-
served only in A. Icevis. A study
of the germination in A. fiisi-
formis shows a general corre-
spondence with the results of
other observers, but certain points
were brought out that do not
seem to have been observed in
A. Iccvis. The spores oi A. fiisi-
formis are protected by a per-
fectly opaque black exospore,
which is covered with small spines or tubercles. These spores
will not germinate readily wdien fresh, but after resting for a
few months grow freely. As in other similar spores, the ex-
ospore is ruptured along the three ridges upon the ventral side
(i. e., that with which it was in contact with the other spores
of the tetrad), and through this cleft the endospore protrudes
as a papilla which sometimes grows into a very long germ
tube, or more commonly divides before it reaches a great
length. Into this tube passes the single chromatophore which,
during the early period of germination, has resumed its green
colour, and with it the oil drops and other contents of the
spore. A good deal of variation was observed here in the
first divisions, as is the case in A. Iccvis. The first division
wall is, in most cases at least, transverse, and is usually followed
by a second similar one, before any longitudinal walls appear.
Then in the end cell two intersecting walls and the formation
of four terminal quadrant cells are often seen (Fig. y6, D), as
in other Hepaticse. Variations from this type are often met

•^Hofmeister (i) ; Gronland (i) ; Leitgeb (7), vol. v. p. 29.

Fig. 75.— a, Young ; B, fully developed
stoma from the epidermis of the
sporogonium of A. Pearsoni, X250.

144

MOSSES AND FERNS

CHAP.

with, and some of these are shown in the figures. V^ery
commonly a second cell is cut off by an oblique wall from the
germ tube subsequent to the first transverse wall, but this does
not, at least in the early stages, develop into a rhizoid, the
first rhizoid being met with only after the young plant has
become a cell body of considerable size (Fig. yy).

Whether the young plant regularly grows from a single
apical cell is difficult to say, but it seems probable, and numerous
forms like Fig. y6, B were encountered where there certainly
seemed to be a two-sided apical cell, such as occurs so often in

Fig. 76. — Anthoceros fusiformis. Germination of the spores, X2S0. A shows a form
with very long germ tube; in B there seems to be a definite apical cell; Fig. D,
2, is an apical view of D, i.

Other Hepaticse. At a later stage (Fig. 77, B) a single apical
cell of the form found in the mature thallus is unmistakably
present. By this time the marginal lobes that give this species
its peculiar crimped appearance begin to develop. They arise
close to the growing point, and grow rapidly beyond it, but do
not show any definite apical growth. The plant at this stage
has a striking resemblance to the prothallium of Equisctuiu.
With the appearance of the marginal lobes, the first of the
mucilage slits appears upon the vental surface (Fig. //), and
from time to time surface cells grow out into the delica-te

IV.

THE ANTHOCEROTES

145

rhizoids, and a little later the first dichotomy of the growing
point takes place. Up to this time the young plants appeared
entirely free from Nostoc, but soon after they were found to
be infected, which no doubt was connected with the formation
of the mucilage slits through which the Nostoc enters the
thallus.

In several species of Anthoceros, especially those inhabiting
regions with a marked dry season, tubers are developed by
means of which the plants are perennial. Howe (3) finds such
tubers developed in A. phymatodcs, of California, and they are
found in A. dicJiotofmiSj of Southern Europe, and in A. tuber-

sp.

Fig. 77. — Anthoceros fusiformis. A, Young plant showing the first rhizoid (r) ; B,
upper part of an older one with the first mucilage cleft (st) ; x, the growing
point, X215.

osus of Australia (see also GoebeL (22), p. 293). The struc-
ture of these tubers has been studied by Ashworth (i), in
A. tuber osus.

Dendroceros

Dendroceros includes about a dozen species of tropical Liv-
erworts, which are distinguished at once from Anthoceros by
the very characteristic form of the thallus. This has a massive
midrib, projecting below, but the rest of the thallus is but one
cell thick and forms lateral wings which are much folded and
lobed, so that the aspect of the plant is somewhat like a Fossom-
bronia. As in Anthoceros, some species have a perfectly com-
10

146 AIOSSES AND FERNS chap.

pact thallus without intercelluar spaces (D. cicJioraceus) , while
in others these are very much developed and the thallus has a
more or less spongy texture, c. g., D. Jaz'aiiiciis. The develop-
ment of the thallus and sporogonium has been studied by Leit'
geb ((/), v., p. 39), and in the main corresponds very closely
to Anthoccros. A difference may be noted, however, in some
details. Thus the form of the apical cell is like that of Pcllia
epiphylla, where the inner segments extend the whole depth
of the thallus, and the division into dorsal and ventral seg-
ments is secondary. The formation of the wings begins near
the apex and is the result of the growth of the marginal cells,
which project strongly and divide rapidly by vertical walls
only. The walls of the cells are thickened at the angles, and
the surface view is curiously like a cross-section of the collen-
chyma of ntany vascular plants. As in Anthoccros mucilage
slits are formed, sometimes on both surfaces of the thallus, and
through these the plant is infected with Nostoc, as in the other
Anthocerotes. In Dcndroccros the Nostoc colonies are very
large and cause conspicuous swellings upon the thallus. All the
species of Dcndroccros that have yet been examined are monoe-
cious.

The antheridia of Dcndroccros (Campbell (20)), which
are larger than those of the other two genera, are developed
singly in strict acropetal succession, forming a row on each side
of the midrib. The youngest ones occur very near the apex of
the shoot. The mother cell arises exactly as in Anthoccros and
Notoihylas, and the periclinal division of the cell lying outside
it takes place \-ery early, so that almost from the beginning-
there are two layers of cells above the antheridial chamber. In
all the younger stages met with by the writer, the antheridium
lay horizontally nearly parallel with the axis of the shoot, and
was attached to the back of the antheridal chamber, instead of
at its base, as in the other genera. (Fig. 78, D.)

The first division in the antheridium is transverse, and sep-
arates the upper part from the stalk. The next divisions may
be alike in both of these cells, being vertical walls intersecting
so as to divide both cells longitudinally into four similar cells.
In the stalk, however, one of these divisions may be suppressed,
and in such cases, the stalk has but two rows of cells instead of
four. In the ripe antheridium the stalk becomes very long, and
is coiled up in the large antheridial chamber.

IV.

THE ANTHOCEROTES

The archegonium of Dendroceros is much Hke that of the
other genera, perhaps more nearly approaching that of Antho-
ceros.

The embryo of Dendroceros resembles more nearly that of
Anthoceros than it does Notothylas. The archesporium is less

a. b.

Fig. 78. — Dendroceros Breutelii. A, Thallus with sporophyte attached, X4; B, apex
of the thallus X600; C, archegonium, X600; D, E, young antheridia, X600.

developed than in either species of Anthoceros that were studied
by the writer, showing only an imperfect division into two lay-
ers when seen in section. No stomata are developed in the epi-

148

MOSSES AND FERNS

CHAP.

dermis of the mature sporophyte, which otherwise closely
resembles that of Anthoceros.

The spores may remain undivided, as in Anthoceros, or in
some species, c. g., D. crispus, they become multicellular before
they are discharged. In this respect these species of Dcndro-
ceros recall Conoccphahis and PcUia, where germination begins
before the spores are set free.

Notothylas

The third genus, Notothylas, is of especial interest, because
it was largely upon the results of his investigations upon this

Fig. 79. — Dciidroccros Brcutclii- A, section of young spororhyte, X2S0; B, section of
mature sporophyte showing spores and elater-like, sterile cells; C, single elater,
X 250.

plant that Leitgeb ( (7), v., p. 39) based his theory of the close
relationship of the Anthocerotes and Jungermanniales. All
of Leitgeb' s observations on the young capsule were made from
herbarium material, and, as he himself admits, were in all cases
embryos that had not fully developed. The writer has made
a very complete examination of the commonest American spe-
cies, A^. orbicularis (z'ahata), and the results of the study of the
development of the sporogonium differ so much from those of
Leitgeb that they will be given somewhat in detail. Mottier

IV.

THE ANTHOCEROTES

149

(2) has also studied this species, and his results agree entirely
with those of the writer.

The thallus much resembles a small Anthoccros, and sec-
tions through it show that in its growth and the development
and structure of the sexual organs there is close correspondence.
The thallus contains very large lacun?e, which are formed in
pretty regular acropetal order, and vertical sections show these
large cavities increasing regularly in size as they recede from
the apex. Similar but less regular lacunse occur in A. fusifor-
mis. The antheridia arise as in Anthoccros, endogenously.
The youngest stage found is shown in Fig. 80, A. Here evi-

F\G. 80. — Notothylas orbicularis. Development of the antheridium. D, cross-section,
the others longitudinal sections; E, nearly ripe antheridium, X300, the other fig-
ures X600; f^. A, the primary antheridial cells.

dently the young antheridia {^) have been formed by the longi-
tudinal division of a single hypodermal cell, whose sister epider-
mal cell has divided again by a transverse wall to form the outer
wall of the antheridial cavity (Figs. A, B). The commonest
number of antheridia formed is four.

Less regularity is found in the next divisions than in Antho-
ccros, although in the main they are the same. This is observ-
able both in longitudinal and cross-sections (see Fig. 80, D).

150

MOSSES AND FERNS

CHAP.

The full-grown antheridium is more flattened than in either
species of Anfhoccros examined by me, and the stalk shorter
and thicker, but otherwise closely resembles it, although the
extremely symmetrical arrangement of the cells, especially of
the wall, is much less noticeable.

The archegonia correspond very closely, both in position
and structure, with those of the other genera, the most marked
peculiarity being the more nearly equal diameter of the cover
cell and central cell, and a corresponding increase in the breadth

Fig. 8i. — Notothylas orbicularis. Development of the archegonium, X6oo; x,

the apical cell.

of the neck canal cell. Subsequently the central cell becomes
much enlarged and the appearance of the fully-developed arche-
gonium is very much like that of Anthoccros (Fig. 8i, A).
As in A. fnsifonnis, the usual number of neck canal cells seems
to be four, and in no case did the number exceed five. The
cover cells were four in number in all the archegonia studied,

IV.

THE ANTHOCEROTES

151

and are larger than in Anthoceros. As in that genus, they are
thrown off when the archegonium opens.

Tlie youngest embryo found was composed of four cells,
and presented quite a different appearance from the corre-
sponding stage in Anthoceros. It is impossible from this stage
to tell whether the first wall in the embryo is vertical or trans-
verse. This embryo consisted of four nearly equal quadrants,
instead of having the two upper cells larger than the lower
ones. By comparison with the older stages there is little doubt
that here the first transverse wall separates the foot from the
capsule, as in Sphcerocarpus, and that the upper cell develops
directly into the capsule instead of the latter being determined
by the second transverse walls. In the next youngest stages

Fig. 82. — Notothylas orbicularis. A, B, Horizontal sections of the growing point with
young archegonia; C, cross-section of the apex of an archegonium, showing the
arrangement of the cover cells; D, longitudinal section of a nearly ripe arche-
gonium, X400.

found (Fig. 83, B) the archesporium was already differentiated.
A comparison of this with the corresponding stage of Antho-
ceros shows conclusively that the two are practically identical
in structure. The columella, evidently formed as in Antho-
ceros, and as there made up of four rows of cells, is surrounded
by the archesporium cut off from the peripheral cells. Leit-
geb's surmise that the columella is a secondary formation is,
therefore, for N. orbicularis at least, entirely erroneous, and it
is extremely likely that when normal specimens of the other
species are examined from microtome sections, in the young

152

MOSSES AND FERNS

CHAP.

Stages at least, a similar columella will be found. The single
embryo that Leitgeb (1. c. PI. IV., Fig. y/) figures of A^. orbi-
cidaris (z'oh'ata) is at once seen to be abnormal, and as his con-
clusions were drawn from a study of similar dead embryos in
the other species, they cannot be accepted without more satis-
factory evidence. While in the main corresponding to the em-
bryo of Anthoccros there are some interesting differences which
are closely associated with the structure of the older sporogo-
nium. The foot is smaller than in Anthoccros and derived only
from the lowest tier of cells. The columella is decidely smaller,
and the archesporium, as well as the young sporogonium wall,
relatively much thicker. As in Anthoccros, the archesporium
does not extend to the foot, but is separated by the zone of

Fig. 83. — Notothylas orbicularis. A, Four-celled embryo; B, C, older embryos, in
longitudinal section. The archesporial cells are shaded. A, X4S0; B, C, X225.

cells which there give rise to the meristem at the base of the
capsule. The form of the embryo is different too. It is pear-
shaped and more elongated than in Anthoccros.

As the embryo develops these differences become more
apparent and others arise. Fig. ^^^^ C shows a stage where
the division of the archesporial cells has begun, and it is at once
apparent how much more conspicuous they are. It is seen too
that the outer cells of the upper ])art of the capsule are also
dividing actively, and that, compared with Anthoccros, the

IV. THE ANrilOCEROTES 153

apical part of the capsule retains its meristematic character for
a much longer period. Corresponding with this, the growth
at the base of the capsule is much less marked. The divisions
in the archesporium are much more active than in Anfhoccros,
and the apical part of the capsule retains its meristematic char-
acter for a much longer period. Corresponding with this, the
growth at the base of the capsule is much less marked. The di-
visions in the archesporium are much more active than in An-
thoceros, and also less regular. At first divisions occur in the
upper portion in all directions, so that above the columella there
is a mass of archesporial tissue much thicker than that below,
and occupying very much more space than the corresponding
tissue in Anthoccros. Longitudinal sections through the basal
part of the older sporogonium show an arrangement of tissues
similar to those in Anthoccros, but there are differences corre-
sponding to those in the young stages. The foot (Fig. 84, A)
is much smaller and flatter, and sometimes shows a very regular
structure. The central part is composed of a compact mass of
rather large cells, between which and the base of the capsule is
a narrow zone of meristematic tissue. The superficial cells do
not always grow out into the root-like processes found in
Anthoccros and Dcndroccros, but may remain short and project
but slightly. The cells are characterised by abundant granular
cytoplasm and conspicuous nuclei, showing that they are prob-
ably not only absorbent cells, but also elaborate the food mate-
rials taken in from the gametophyte. The gradual transition
of the differentiated tissues above into the meristem at the base,
is precisely as in Anthoccros, and sections at that point in the
two genera can scarcely be distinguished from one another.
The columella (in longitudinal section) in both shows four par-
allel rows of cells, outside of which lies the single row of arche-
sporial cells, and four rows of cells belonging to the wall of the
capsule.

As the section is examined higher up, however, there are
marked differences, especially in the divisions of the arche-
sporium. The first divisions in the archesporium of Nofothylas
are periclitial, and for a short distance it is two-layered, as it is
permanently in Anthoccros; but still further up it widens very
rapidly by the formation of repeated periclinal walls, and soon
comes to be much thicker than either the columella or the capsule
wall. A further study of the developing archesporium shows

154

MOSSES AND FERNS

CHAP.

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IV.

THE ANTHOCEROTES

ISS

that the divisions occur with a good deal of regularity. The
archesporial cells are divided Ijy alternating vertical and trans-
verse walls into four layers of cells instead of two, as in Antho-
ceros, and these cells are arranged in regularly placed transverse
rows. At first the cells appear alike, but later there is a separa-
tion into sporogenous and sterile cells as in Anthoceros. Each
primary transverse row of cells becomes divided into two. The
upper row grows much faster, and its cells become swollen and
the cytoplasm more granular, while the lower row has its cells
remaining flattened and more transparent, i. e., there is a sep-
aration of the archesporium into alternate layers of sporogenous
and sterile cells as in Anthoceros, but here the
number of cells is double that in the latter, and
the longer axis of the cells is transverse instead
of vertical. In the portion of the archesporium
above the columella these alternate layers of
spore mother cells and sterile cells extend com-
pletely across, and Leitgeb has correctly fig-
ured this, although he probably was mistaken
in assuming that this arrangement extended to
the base of the capsule.

The further development of the capsule is
much like that of Anthoceros, but the division
of the chloroplast takes place before the spore
mother cells are isolated, and the primary chlo-
roplast is evident almost as soon as the sporog-
enous cells are recognisable as such. The
cells of the columella do not become as elon-
gated as in Anthoceros, and develop thicken-
ings much like those of the sterile cells of the
archesporium; and it was this partly that led
Leitgeb to the conclusion that even where a
definite columella was present it probably arose
as a secondary formation in the archesporium,
similar to the formation of the axial bundle of
elaters in Pellia, and that in Notothylas as in
the Jungermanniales, the archesporium arose
from the inner of the cells formed by the first
periclinal walls, and not from the outer ones. That this is not
true for A'', oribictilaris is shown beyond question from sections
of both the older and younger sporogonium, and it w^ould be

S^i

lq2

Fig. 85. — Longitu-
dinal section of a
nearly ripe sporo-
gonium of A'', or-
bicularis, X50.

156 MOSSES AND FERNS chap.

extremely strange if the other species should differ so radically
from this one as would be the case were Leitgeb's surmise
correct.

The wall of the capsule does not develop the assimilative
apparatus of the Anthoccros capsule, and stomata are com-
pletely absent from the epidermis. The inner layers of cells
are more or less completely disorganised, and they probably
serve to nourish the growing spores, which here, of course, are
correspondingly more numerous than in Anthoccros. As in the
latter the sterile cells from a series of irregular chambers in
which the spores lie. At maturity these sterile cells separate
into irregular groups. Their walls are marked with short
curved thickened bands, yellowish in colour like the wall of the
ripe spores. At maturity the capsule projects but little beyond
its sheath, and opens by two valves. In some species, c. g., N.
melanosporaj the capsule often opens irregularly.

The Evolution of the Anthoccrotes

The Anthocerotes form a most interesting series of forms
among themselves, but are also of the greatest importance in
the study of the origin of the higher plants. Unquestionably
Notothylas represents the form which most nearly resembles the
other Liverworts, but until the other species are investigated
further we shall have to assume that the type of the sporo-
gonium is essentially different from that of the lower Hepaticse,
and corresponds to that of the other Anthocerotes. The pri-
mary formation of the columella and the subsequent differentia-
tion of the archesporium occur elsewhere only in the S]:)hagna-
ceae. From NototJiyhis, where the archesporium constitutes
the greater part of the older sporogonium, and the columella
and wall are relatively small, there is a transition through the
forms with a relatively large columella to Dcndroccros, wdiere
the spore formation is much more subordinated and a massive
assimilative tissue developed. Tn NotothyJas the secondary
growth of the capsule at the base, while it continues for some
time, is checked before the capsule projects much beyond its
sheath. In Dcndroccros the growth continues much longer,
although it does not continue so long as in Anthoccros. The
assimilative system of tissue in the latter Is finally completed
by the development of perfect stomata, and the growth of the

IV. THE ANTIIOCEROTES IS7

capsule is unlimited. All that is needed to make the spore
phyte entirely independent is a root connecting it with the
earth.

The Inter-relationships of the Hepatiecu

From a review of the preceding account of the Liverworts,
it will be apparent that these plants, especially the thallose
forms, constitute a very ill-defined group of organisms, one set
of forms merging into another by almost insensible gradations,
and this is not only true among themselves, but applies also
to some extent to their connection with the Mosses and
Pteridophytes. The fact that the degree of development of
gametophyte and sporophyte does not always correspond makes
it very difficult to determine which forms are to be regarded as
the most primitive. Thus while Riccia is unquestionably the
simplest as regards the sporophyte, the gametophyte is very
much more specialised than that of Anenra or Sphceroearpns,
The latter is, perhaps, on the whole the simplest form we know,
and we can easily see how from similar forms all of the other
groups may have developed. The frequent recurrence of the
two-sided apical cell, either as a temporary or permanent con-
dition in so many forms, makes it probable that the primitive
form had this type of apical cell. From this hypothetical form,
in which the thallus was either a single layer of cells or with an
imperfect midrib like Sphceroearpns, three lines of development
may be assumed to have arisen. In one of these the differenti-
ation was mainly in the tissues of the gametophyte, and the
sporophyte remained comparatively simple, although showing
an advance in the more specialised forms. The evolution of
this type is illustrated in the germinating spores of the Mar-
chantiacese, where there is a transition from the simple thallus
with its single apical cell and smooth rhizoids to the complex
thallus of the mature gametophyte. In its earlier phases it re-
sembles closely the condition wdiich is permanent in the simpler
anacrogynous Jungermanniacese, and it seems more probable
that forms like these are primitive than that they have been de-
rived by a reduction of the tissues from the more specialised
thallus of the Marchantiaceae. Sphceroearpns, showing as it
does points of affinity with both the lower Marchantiales and
the anacrogynous Jungermanniales, probably represents more
nearly than any other known form this hypothetical type. Its

iD'

8 MOSSES AND FERNS chap.

sporogonium, however, simple as it is, is more perfect than
that of Riccia, and if our hypothesis is correct, the Marchanti-
ales must have been derived from Sphcerocarpiis-Yike forms in
which the sporophyte was still simpler than that of existing
species. Assuming that this is correct, the further evolution
of the Marchantiales is simple enough, and the series of forms
from the lowest to the highest very complete.

In the second series, the Jungermanniales, starting with
Spliccrocarpus, the line leads through Anciira, PcUia, and simi-
lar simple thallose forms, to several types with more or less
perfect leaves— ^.^.^ Blasia, Fossoinhronia, Trcubia, Haplomit-
rium. These do not constitute a single series, but have evi-
dently developed independently, and it is quite probable that
the typical foliose Jungermanniace?e are not all to be traced
back to common ancestors, but have originated at different
points from several anacrogynous prototypes.

The systematic position of the Anthocerotes is more diffi-
cult to determine, and their connection with any other existing
forms known must be remote. While the structure of the thal-
lus and sporogonium in Noiofhylas show-s a not very remote
resemblance to the corresponding structures in Sphccrocarpus,
it must be remembered that the peculiar chloroplasts of the
Anthocerotes, as well as the development of the sexual organs,
are peculiar to the group, and quite different from other Liver-
worts. To find chloroplasts of similar character, one must go
to the green Alg?e, where in many Confervacere very similar
ones occur. It is quite conceivable that the peculiarities of the
sexual organs may be explained by supposing that those of
such a form as Sphccrocarpus, for example, should become co-
herent with the surrounding envelope at a very early stage, and
remain so until maturity. In Ancnra we have seen that the
base of the archegonium is confluent with the thallus, in which
respect it oft'ers an approach to the condition found in the An-
thocerotes; but that this is anything more than an analogy is
improbable. The origin of the endogenous antheridium must
at present remain conjectural, but that it is secondary rather
than primary is quite possible, as we know that occasionally the
antheridium may originate superficially. In regard to the
sporogonium, until further evidence is brought forward to
show that Notothylas may have the columella absent in the early
stages, it must be assumed that its structure in the Anthocerotes

iv. THE ANTHOCEROTES I59

is radically different from that of the other Liverworts. Of the
lower Hepaticse Spliccrocarpus perhaps offers again the nearest
analogy to Nototliylas, but it would not be safe at present to
assume any close connection between the two. Of course the
very close relationships of the three genera of the Anthocerotes
among themselves are obvious.

On the whole, then, the evidence before us seems to indicate
that the simplest of the existing Hepaticse are the lower thallose
Jungermanniales, and of these Sphcerocarpiis is probably the
most primitive. The two lines of the Marchantiales and Jun-
germanniales have diverged from this common ancestral type
and developed along different lines. The Anthocerotes cannot
certainly be referred to this common stock, and differ much
more radically from either of the other tw^o lines than these
do from each other, so that at present the group must be looked
upon as at best but remotely connected with the other Hepaticse,
and both in regard to the thallus and sporophyte has its nearest
affinities among certain Pteridophytes. The possibility of sep-
arate origin of the Anthocerotes from Coleochcete-Wkt ancestors
is conceivable, but it seems more probable that they have a com-
mon origin, very remote, it is true, with the other Liverworts.
They may probably best be relegated to a separate class, coordi-
nate with the Hepaticse and Musci.

CHAPTER V

THE MOSSES (MUSCI) : SPHAGNALES— ANDRE.EALES

The ]\Iosses offer a marked contrast to the Hepaticae, for
while the latter are pre-eminently a generalised group, the
Mosses with a very few exceptions form one of the most
sharply defined and specialised groups of plants known to us.
Although much outnumbering the Liverworts in number of
species, as well as individuals, the differences in structure be-
tween the most extreme forms are far less than obtain among
the Liverworts. While the latter occur as a rule in limited
numbers, and for the most part where there is abundant
moisture, the Mosses often cover very large tracts almost to
the exclusion of other vegetation, especially in northern
countries. In more temperate regions, the familiar peat-bogs
are the best known examples of this gregarious habit. Mosses
are for the most part terrestrial, and are found in almost all
localities. Some grow upon organic substrata, especially de-
caying wood, and are to a greater or less extent saprophytic.
Haberlandt (4) first called attention to this, and investigated
a number of forms, among them Rhynchosteghnn niuralc,
Eurynchiuin prcclonguin, JVcbcra nutans, and others, and in
these found that the rhizoids had the power of penetrating the
tissue of the sul)stratum, much as a fungus would do. The
most remarkable case, however, is Bnxbaumia, where the
leaves are almost completely absent and the saprophytic habit
very strongly pronounced. Most of the Mosses, however, are
abundantly provided with assimilative tissue, and grow upon
almost every substratum, although most of them are pretty
constant in their habitat. A number of species are typically

aquatic, c. g., Fontinalis and many species of Sphagmun and

160

CH.v. MOSSES (MUSCI): SPHAGNALES—ANDRE.EALES i6i

Hypiiuui; others grow regularly in very exposed situations on
rocks, e. g., Andrecea. Very many, like Fiinaria hygrometrica
and Atrichiim iindiilatum, grow upon the earth; and others
again, like species of Mnium and TJmidiuin, seem to grow
exclusively upon the decaying trunks of trees. Indeed Mosses
are hardly absent from any locality except salt water. With
the exception of the Sphagnaceae and Andreceacese, and pos-
sibly Archidium, the type of structure found among the Mosses
is extraordinarily constant, and they may all be unhesitatingly
referred to a single order, the Bryales, which includes within
it an overwhelming majority of the species.

The gametophyte of the Musci always shows a well-
marked protonema, which in most cases has the form of an
extensively branching alga-like filamentous structure, from
which later a distinct leafy axis arises as a lateral bud. In
Sphagnum this protonema is a flat thallus, and the same is true
of Tctr aphis and a few other forms, but the filamentous proto-
nema is very much more common. The gametophore arises
from this protonema as a lateral bud, which develops a
pyramidal apical cell, from which three sets of segments are
cut off, each segment producing a leaf. The only exception
to this, so far as is known at present, is the genus Fissidens
(Leitgeb (2)), where the apical cell is wedge-shaped, and
only two sets of segments are formed. Upon these leafy
branches the sexual organs are borne. The relative degree of
development of the protonema and the gametophore differ
much in different forms. Thus in the Phascaceae the proto-
nema is permanent, and the gametophore small and poorly
developed. In the higher Mosses the protonema disappears
more or less completely, and the assimilative functions are
entirely assumed by the large highly developed gametophore,
which is capaljle of reproducing itself by direct branching
without the intervention of the protonema. The commonest
type of gametophore is the upright stem with the leaves ar-
ranged radially about it, but in many creeping forms, such as
some species of Mnium, Hypmim, etc., the gametophore is
more or less dorsi ventral ; but in these the apical cell is pyram-
idal, and produces three rows of leaves. Growing out from
the base of the stem in most Mosses, and fastening it to the
substratum, are numerous brown rhizoids which are not, how-
ever, morphologically distinct from the protonema. Thus if

i62 MOSSES AND FERNS chap.

a turf of growing Moss is turned upside down, the rhizoids
thus exposed to the hght very soon develop chlorophyll, and
grow out into normal protonemal filaments.

In most of the Mosses the leaves show a one-layered lamina
traversed by a midrib, which may be quite small or very
massive. This midrib is made up in part of elongated thick-
walled sclerenchyma, and contains a conducting tissue. The
highest grade of development of the leaf is met with in the
PolytrichacecOj where the midrib is very massive and peculiar
vertical laminae of chlorophyll-bearing cells grow out from the
surface of the leaf. In Buxhaumia the leaves are almost en-
tirely abortive. The peculiar leaves of Sphagnum will be re-
ferred to later, as well as the details of structure of the leaves
of other forms.

The stem, except in the lowest forms, is traversed by a
well-defined central strand of conductive tissue, and in a few
of the highest ones, e. g. Polytrichuni, there are in addition
smaller bundles, continuations of the midribs of the leaves,
recalling the "leaf-traces" found in the stems of Spermato-
phytes.

The types of non-sexual reproduction among the Musci
are extraordinarily various, and a careful study of them shows
that the morphological connection between the protonema and
gametophore is a very intimate one, as they may arise recip-
rocally one from the other. With the exception of certain
resting buds developed from the protonema it appears (Goebel
(lo), p. 170) that the formation of the leafy stem is always
preceded by the protonema. The latter arises primarily from
the germinating spores, but may develop secondarily from
almost any part of the gametophore or even in exceptional
cases from the cells of the sporophyte (Pringsheim (2) ;
Stahl (i)). From these protonemal filaments new gameto-
phores arise in the usual way. The gametophore itself, es-
pecially where it is large and long lived, by the separation of
its branches rapidly increases the number of new individuals.
This is especially marked in Sphagnum, where this is the
principal method of propagating the plants. Special organs
of propagation in the form of gemm?e also occur, and these
may develop from the protonema or from the gametophore
Tctraphis pcUitcida (Fig. 118) is a good example, showing
these specialised gemmae which after a time germinate by

MOSSES (MUSCI): SPHAGNALES—ANDRE^ALES 163

giving rise to a protonema upon which, as usual, the gameto-
phore arises as a bud. In size the gametophore of the Mosses
ranges from a milHmetre or less in height in Buxhamnia and
Ephementm to 30 to 50 cm. in the large Polytrichacese and
Fontinalis. The branching of the gametophore is never
dichotomous, and so far as is known the lateral branches arise,
not in the axils of the leaves, but below them. Underground

Fig. 86. — Climacium Americanum, showing the formation of stolons, X2»

Stems or stolons, which afterwards develop into normal leafy
axes, are common in many forms, e. g., Climacium (Fig. 86).
The sexual organs are borne either separately or together
at the summit of the gametophoric branches. Where the
plants are dioecious, it sometimes happens that the two sexes
do not grow near together, in which case, although archegonia

i64 MOSSES AND FERNS chap.

may be plentiful, they fail to be fecundated and thus no cap-
sules are developed. This no doubt accounts for the extreme
rarity of the sporogonium in many Mosses, although in other
cases, c. g., SpJiagJiiiui, it would appear that the formation of
the sexual organs is a rare occurrence. These resemble in gen-
eral those of the Hepaticae, but differ in some of their details.
The leaves surrounding them are often somewhat modified,
and in the case of the male plants (Atrichuin, Polytridiuni)
different in form and colour from the other leaves, so that the
whole structure looks strikingly like a flower. As a rule, the
archegonial receptacles are not so conspicuous. The early
divisions of the archegonium correspond closely with those of
the Liverworts, but after the ''cover cell" is formed, instead
of dividing by cross walls into four cells, it functions for some
time as an apical cell, and to its activity is largely due the fur-
ther development of the neck. The venter is usually very
much more massive than in the Hepatic?e, and the egg small.

The antheridia, except in Sphagnum, are borne also at the
apex of the stem, whose apical cell does not always, at any rate,
become transformed into an antheridium, as we sometimes find,
especially in species of Atrichum and Polytrichiun, that the
axis grows through the antheridial group and develops a leafy
axis, which later may form other antheridia at its apex. Where
the plants are dioecious the males are usually noticeably smaller
than the females. The antheridia, except in Sphagnuin, are
very uniform in structure, and like the archegonium exhibit a
very definite apical growth (Fig. 102). The wall remains
one-layered, as in the Liverworts, and often the chromatophores
in its cells become red at maturity, as in some Liverworts, e. g.,
Anthoccros. The ripe antheridium is in most Mosses clul>
shaped, and the sperm cells are discharged while still in con-
nection, the complete isolation of the sperm cells only taking
place some time after the mass has lain in water. Li SpJiag-
num the antheridia are much like those of certain leafy Liver-
worts, and stand singly in the axils of the leaves of the male
branches.

Holferty (i) describes and figures a number of interesting
abnormalities in Muiuui cuspidatuin in which organs are some-
times developed which are intermediate in character between
archegonia and antheridia.

The sporophyte of the Mosses reaches a high degree of

V. MOSSES (MUSCI): SPHAGNALES—ANDREJEALES 165

development in the typical forms, and shows great uniformity,
both in its development and in the essential structure of the
full-grown sporophyte. With the exception of Sphagnum,
which will be referred to more specially later, the early growth
of the sporogonium is due to the segmentation of a two-sided
apical cell. The separation of the archesporium takes place at
a late period, and like that of Anthoceros it occupies but a very
small part of the sporogonium, which in all the higher forms
attains a considerable size and complexity. All the archesporial
cells form spores, and no trace of elaters can he found.

In all but the lower types, the sporogonium becomes
differentiated into a stalk (seta) and a capsule. This differ-
entiation is gradual, and the elongation of the seta is not a
rapid process, due simply to an elongation of the cells, but is
caused by actual growth and cell division. In SpJiagnnm
and Andrecca, where no seta is present, the axis of the gameto-
phore elongates and forms a sort of stalk (pseudopodium),
which carries up the capsule above the leaves.

The formation of the capsule and seta takes place by a
rapid enlargement of the upper part of the very much elongated
embryo about the same time that the archesporium becomes
recognisable. This enlargement is accompanied by a separa-
tion of the cells of two layers of the wall, by which an inter-
cellular space is formed which later may become very large
(Figs. 109-112). A second similar space may be developed in-
side the archesporium, but this is found only in the Polytrich-
acege. In the Sphagnaceae and the Andreseaceae this space is
not developed. These lacunae are traversed by protonema-like
filaments of chlorophyll-bearing cells, and the cells of the mass-
ive wall of the capsule also contain much chlorophyll, so that
there is no question that the sporogonium is capable of assimila-
tion. Stomata, much like those of Anthoceros or the vascular
plants, occur upon the basal part of the capsule in many species,
but are not always present.

In Sphagnum and all the higher Bryales the capsule opens
regularly by means of a circular lid or operculum. This in the
latter group is a most characteristic structure, and with its
accompanying structures, the "annulus" and ''peristome," form
some of the most important distinguishing marks of different
genera and species. When ripe, the operculum falls off and
the ripe spores are set free. The teeth of the peristome, by

i66 MOSSES AND FERNS chap.

their hygroscopic movements, play an important part in scat-
tering the spores, and physiologically take the place of the
elaters of the Hepaticoe.

Some ^Mosses live but a few months, and after ripening
their spores, die. This is the case with Fiinaria hygromctrica,
at least in California. Other IMosses are perennial, and some
species of peat or tufa-forming IMosses seem to have an un-
limited growth, the lower portions dying and the apices g^'-row^
ing on until layers of peat or tufa of great thickness result,
covered over with the still living plants whose apices are the
direct continuation of the stems which form the basis of the
mass.

\\^ith the exception of a very few forms all the Mosses are
readily referable to three orders. The first two, the Sphagnales
and the Andreseales, are represented each by a single genus, and
are in several respects the types that come nearest the Liver-
worts. All the other Mosses, except perhaps Archidhim and
Buxhaiimia, conform to a very well-marked type of develop-
ment, and may be referred to a common order, the Bryales.
The Phascaceae or cleistocarpous Mosses are sometimes sep-
arated from the higher Bryales as a distinct order, but a study
^f their development shows that they belong to the same series,
and only differ in the degree of development from the more
specialized stegocarpous forms.

Order I. — Sphagnales

The Sphagnales, or Peat-Mosses, are represented by the
single genus Sphagnum. They are Mosses of large size,
which, as is w^ell known, often cover large tracts of swampy
land and about the borders of lakes, forming the familiar peat-
bogs of northern countries. Owing to the empty cells in the
leaves and outer layers of the stem, they suck up water like a
sponge, and the plants when growing are completely saturated
with water. The colour is usually pale green, but varies much
in depth of colour, and in many species is red or yellow. When
dry the colour is much duller, largely owing to the opacity of
the dry, empty cells which conceal to a great extent the colour
of the underlying tissues. They branch extensively, and, ac-
cording to Schimper, a branch is always formed corresponding
to every fourth leaf; but Leitgeb has shown that although this

MOSSES (MUSCI): SPHAGNALES—ANDRE^ALES 167

is the rule numerous exceptions to it occur. In sterile plants
the branches are of two kinds, long flagellate branches which
hang down almost vertically and are applied to the stem, and
much shorter ones that are crowded together at the apex and
have only a limited growth. The leaves are inserted on the

Fig. ?>7. ■^Sphagnum (sp) ; A, B, Young protonemata, X262; C, an older protonema
with a leafy bud (A:), X about 40; r, marginal rhizoids.

Stem by a broad base, and taper to a more or less well-marked
point. According to Schimper, the divergence of the leaves
of the main axis is always two-fifths, but on the smaller
branches variations from this sometimes occur. The leaves

i68

MOSSES AND PERNS

CHAP.

show no trace of a midrib. As the axis elongates the leaves
become separated, as well as the lower branches, but upon the
smaller branches they remain closelv imbricated. Rhizoids
are present only in the earlier stages of the plant's growth, and
are only occasionally found in a very rudimentary condition in
the older ones.

The spores of Sphagiium on germination form first a very
short filament, which soon, at least when grown upon a solid
substratum, forms a flat thallus, which at first sometimes grows

by a definite apical cell (C.
Muller (3)). It first has a spatu-
late shape (Fig. 87, A, B), which
later becomes broadly heart-shaped,
and closely resembles in this condi-
tion a young Fern prothallium, for
which it is readily mistaken. The
older ones become more irregular
and may attain a diameter of sev-
eral millimetres. The thallus is
but one cell thick throughout its
whole extent, and is fastened to the
earth by colourless rhizoids. Later
similar filaments grow out from the
marginal cells of the thallus, and a
careful examination shows that
they are septate, and closely re-
semble the protonemal filaments of
other Mosses. Like those, the

Fig. B8. — sphagnum squarrosum. gepta, CSpCciallv iu tllC COlourlcSS
Leafy shoot with sporophytes "^ '

(sp), borne at the end of leaf- oucs, are strougly obliquc. J licse
less branches, or "pseudopodia," marginal protoucuial threads may,

according to Hofmeister (i) and
Schimper (i), produce a flattened thallus at their extremity,
and thus the number of flat thalli may be increased. Schimper
states that if the germination takes place in water, the forma-
tion of a flat thallus is suppressed and the protonema remains
filamentous, but Goebel disputes this.

Li the few cases observed by mc, only one leafy axis arose
from each thalloid protonema, and although this is not expressly
stated by Hofmeister and Schimper, their figures would indi-
cate it. At a point, usually near the base, a protuberance is

^W^

V. MOSSES (MUSCI): SPlIAGNALES—ANDRE/liALES 169

formed by the active division of the cehs, in a manner probably
entirely similar to that in other Mosses, and this rapidly as-
sumes the form of the young stem. The first leaves are very
simple in structure, and are composed of perfectly uniform
elongated quadrilateral cells, all of which contain more or less
chlorphyll. Like the older ones, however, they show the char-
acteristic two-fifth divergence. Schimper states that the fifth
leaf, at the latest, shows the differentiation into chlorophyll-

Fig. 89. — Sphagnum cymbifolium. A, Median longitudinal section of a slender branch;
X, the apical cell; B, part of a section of the same farther down, showing the
enlarged cells at the bases of the leaves, and the double cortex {cor) ; C, cross-
section near the apex of a slender branch; D, glandular hair at the base of a
young leaf — all XS25.

bearing and hyaline cells, found in the perfect leaves. The
first leaves in which this appears only show it in the lower part
the cells of the apex remaining uniform.

170 MOSSES AND FERNS chap.

At the base of the young plant very deHcate colourless
rhizoids are developed, and these show the oblique septa so
general in the rhizoids of other Mosses. As the plant grows
older these almost completely disappear.

The apex of the stem and branches is occupied by a pyram-
idal apical cell with a very strongly convex outer free base.
From the lateral faces of the apical cell, as in the acrogynous
Liverworts, three sets of segments are formed. The whole
vegetative cone is slender, especially in the smaller branches.
The first division in the young segment is parallel to its outer
face, and separates it into an inner cell, from which the central
part of the axis is formed, and an outer cell which produces the
leaves and cortex.

The second wall, which is nearly horizontal, divides the
outer cell of the segment into an upper and a lower cell, the
former being much broader than the latter, which is mainly
formed from the kathodic half of the segment, which is higher
than the anodic half (Leitgeb (i)). The next wall divides
the upper cell into an upper and a lower one, the former being
the mother cell of the leaf, the lower, with the other basal cell,
giving rise to the cortex. Growth proceeds actively in the
young leaf, which soon projects beyond the surface of the stem,
and by the formation of cell walls perpendicular to its surface
forms a laminar projection. The position of the cell walls in
the young leaf is such that at a very early period a two-sided
apical cell is established, which continues to function for a long
time, and to whose regular growth the symmetrical rhomlx)idal
form of the cells of the young leaf is largely due (Fig. 90).
The leaves do not retain their original three-ranked arrange-
ment, but from the first extend more than one-third of the cir-
cumference of the stem, s"o that their bases overlap, and the
leaves become very crowded, and the two-fifth arrangement is
established. The degree to which the central tissue of the stem
is developed varies with the thickness of the branch. In the
main stem it is large, but in the small terminal branches it is
much less developed, as well as the cortex, which in these small
branches is but one cell thick. Later the cortex of the large
branches becomes two-layered (Fig. 89, B), and is clearly sep-
arated from the central tissue, whose cells in longitudinal sec-
tion are very much larger. In such sections through the base

V. MOSSES (MUSCI): SPHAGNALES—ANDREMALES 171

of very young leaves characteristic glandular hairs are met
with. They consist of a short basal cell and an enlarged ter-

minal cell containing a densely granular matter, which from
its behaviour with stains seems to be mucilaginous. The form

172 MOSSES AND FERNS chap.

of the secreting cell is elongated oval (Fig. 89, D), and the
hair is inserted close to the base of the leaf, upon its inner sur-
face.

The young leaf consists of perfectly uniform cells of a
nearly rhomboidal form (Fig. 90, A), and this continues until
the apical growth ceases. Then there begins to appear the sep-
aration into the chlorophyll-bearing and hyaline cells of the
mature leaf. This can be easily followed in the young leaf,
where its base is still composed of similar cells, but where
toward the apex the two sorts of cells become gradually differ-
entiated. The future hyaline cells grow almost equally in
length and breadth, although the longitudinal growth some-
what exceeds the lateral. These alternate regularly with the
green cells, which grow almost exclusively in length, and form
a network with rhomboidal meshes, whose Interstices are occu-
pied by the hyaline cells. The latter at first contain chloro-
phyll, which soon, however, disappears ; and finally, as is well
known, they lose their contents completely, and in most cases
round openings are formed in their walls. The protoplasm is
mainly used up in the formation of the spiral and ring-shaped
thickenings upon the inner surface of the wall, so characteristic
of these cells (Fig. 90, D). The chlorophyll cells are some-
times so crowded and overarched by the hyaline ones that they
are scarcely perceptible, and of course in such leaves the green
colour is very faint. Cross-sections of the leaves show a char-
acteristic beaded appearance, the large swollen hyaline cells
regularly alternating with the small wedge-shaped sections of
the green cells (Fig. 90, E). Russow (4) has shown that the
leaves of the sporogonial branch retain more or less their primi-
tive character, and the division into the two sorts of cells of the
normal leaves is much less marked. He connects this with the
necessity for greater assimilative activity in these leaves for
the support of the growing sporogonium. From his account
too it seems that the stem leaves lose their activity very early.

The degree of development of the thickenings upon the
walls of the hyaline cells varies in different species, and in dif-
ferent parts of the leaf. Jt is, according to Russow, best de-
veloi)ed in the upper half of the leaf, where these thickenings
have the form of thin ridges projecting far into the cell cavity.

The development of the central tissue of the stem varies.

V. MOSSED' (MUSCI): SPHAGNALES—ANDREJEALES i73

The central portion usually remains but little altered and con-
stitutes a sort of pith composed of thin-walled colourless par-
enchyma, which merges into the outer prosenchymatous tissue
of the central region. The cells of the latter are very thick
walled, and elongated, and their walls are usually deeply stained
with a brown or reddish pigment. In their earlier stages, ac-
cording to Schimper ((i), p. 36), the prosenchyma cells have
regularly arranged and characteristic pitted markings on their
w^alls, but as they grow older and the walls thicken, these be-
come largely obliterated. Cross-sections of these prosenchyma
cells show very distinct striation of the wall (Fig. 90, G),
which become less evident as they approach the thinner-walled
parenchyma of the central part of the stem. No trace of a cen-
tral cylinder of conducting tissue, such as is found in most of
the Mosses, can be found in Sphagmun, and this is correlated
with the absence of a midrib in the leaves.

The cortex at first forms a layer but one cell thick, but is
from the first clearly separated from the axial stem tissue. In
the smallest branches it remains one-layered (Fig. 89, C), but
in the larger ones it early divides by tangential walls into two
layers, wdiich at this stage are very conspicuous (Fig. 89, B).
Later there may be a further division, so that the cortex of the
main axes frequently is four-layered. While the cells of the-
young cortex are small, and the tissue compact, later there is
an enormous increase in the size of the cells, which finally lose
their protoplasmic contents and resemble closely the hyaline
cells of the leaves. Like the latter, the cortical cells are per-
fectly colourless, and usually have similar circular perforations
in their walls. The resemblance is still more marked in 5^.
cymhifolmm, where there are spiral thickened bands, quite like
those of the hyaline leaf cells. On the smaller branches the
cortical cells (Schimper (i), p. 39), have been found to be of
two kinds — the ordinary form and curious retort-shaped cells
with smooth w^alls and single terminal pore.

The Branches

Leitgeb ( i ) has studied carefully the branching of Sphag-
num, which corresponds closely to the other Mosses investi-
gated. The branch arises from the lower of the two cells into

174 MOSSES AND FERNS chap.

which the outer of the two primary cells of the segment is
divided. In this cell, which ordinarily constitutes part of the
cortex, walls are formed in such a way that an apical cell of the
ordinary form is produced. These lateral branches themselves
branch at a very early period, and form tufts of secondary ones.
Schimper was unable to make out clearly what the nature of
this branching was, but suggested a possible dichotomy. Leit-
geb, however, concludes that it is monopodial, and that each
branch corresponds to a leaf, as do the primary branches. The
growth of all the lateral branches, both the descending flagellate
ones and the short upright ones at the top of the stem, is limited,
and lasts through one vegetative period only. This, however,
is not true of the branches that are destined to continue the axis
These are apparently morphologically the same as those whose
growth is limited, but they continue to grow in the same man-
ner as the main axis.

The Sexual Organs

The sexual organs in Sphagnum are produced on branches
that do not differ essentially from the sterile ones. The leaves
of the antheridial branches are usually brightly coloured, — red,
yellow, or dark green, and are closely and very regularly set
so that the branch has the form of a small catkin (Fig. 91, A).
The antheridia stand singly in the axils of the leaves, and Leit-
geb states that their position corresponds with that of branches,
with which he regards them as homologous, having observed
in some cases a bud occupying the place of an antheridium. He
studied in detail their development, which differs considerably
from that of the other Mosses. The antheridium arises from
a single cell whose position corresponds to that of a lateral bud
on an ordinary branch. This cell grows out into a papilla and
becomes cut off by a transverse wall. The outer cell continues
to elongate without any noticeable increase in diameter, and a
series of segments are cut off from the terminal cell by walls
parallel to its base, so that the young antheridium consists of
simply a row of cells, comparable to the very young anther-
idium of the Marchantiaceae. Intercalary transverse divisions
may .also arise, and later some or all of the cells, except the ter-
minal one, divide by longitudinal walls, usually two intersect-
ing ones in each cell, so that the antheridium rudiment at this

MOSSES (MUSCI): SPHAGNALES—ANDRE^ALES i75

stage is composed of a long stalk composed of several rows of
cells, usually four, and a terminal cell which later gives rise to

Fig. 91. — A, Male catkin of Sphagnum cymbifolium, X50; B, young antheridium of
S. acutifolium, X350; C, opened antheridium of the same species; D, spermatozoid,
Xiooo (about); E, female branch with sporogonium of S. acutifolium, slightly
magnified; cal, calyptra. A, C, E, after Schimper; B, after Leitgeb.

the body of the antheridium. The first divisions in the body
of the antheridium only take place after the stalk has become

176 MOSSES AND FERNS ' chap.

many times longer than the terminal cell, and is divided into
many cells.

The account of the development of the antheridium given
by Hofmeister and Schimper is incomplete, and differs in some
respects from that of Leitgeb. Neither of the former observ-
ers seems to have clearly recognised the presence of a definite
apical cell from the first. Schimper ((i), p. 45), states that
after the stalk has been formed four rows of segments arise
from the terminal cell; to judge from the somewhat vague
statements of Hofmeister ((i), p. 154), it appears that he re-
garded the terminal growth as taking place by the activity of
a two-sided apical cell, as in other Mosses. Leitgeb states that,
while this form of growth does frequently occur, usually the
divergence of the segments is not exactly half, and the segments
do not stand in two straight rows, but some of them are inter-
calated between these, forming an imperfect third row. Each
segment is first divided by a radial wall into nearly equal parts,
and these are then divided into an outer and an inner cell, and
from the latter by repeated divisions the sperm cells are formed.
The body of the full-grown antheridium is broadly oval, and
both in its position and shape recalls strongly that of such a
foliose Liverwort as Porella.

The development of the spermatozoids has been carefully
followed by Guignard ((i), p. 69), and corresponds in the
main with that of the Hepatic?e. A peculiar feature is the
presence of a pear-shaped amylaceous mass, firmly attached to
the posterior coil. This becomes evident at a very early stage
in the development and remains unchanged up to the time the
spermatozoids are liberated (Fig. 91, D). The vesicle in
which it is enclosed collapses, leaving only the large starch
granule, which finally becomes detached. The free spermato-
zoid has about two complete coils, and in form recalls that of
CJiara. The cilia are two and somewhat exceed in length the
body.

The ripe antheridium is surrounded by a weft of fine
branching hairs, which Schimper suggests serve to supply it
with moisture.^ It opens by a number of irregular lobes (Fig.
91, C), precisely as in Porella, and, like that, the swelling of
the cells is often so great that some of them become entirely

^ These are probably the hyphae of a fungus.

V. MOSSES (MUSCI): SPHAGNALES—ANDRE^ALES \77

detached. Schimper states that antheridia may be formed at
any time, but they are more abundant in the late autumn and
winter.

The archegonia are found at the apex of some of the short

'>^^\yU}^

Fig. 92. — Sphagnum acutifoUum. Development of the embryo (after Waldner). A-D,
Median optical section; E, F, cross-sections. A, D, E, F, X360; C, X315; D,
X153.

branches at the summit of the plant, which externally are indis-
tinguishable from the sterile branches. The development of
the archegonia has not been followed completely, but to judge
from the stages that have been observed and the mature arche-

178 MOSSES AXD FERNS chap.

gonium, its structure and development correspond closely to
that of the other Mosses. As in these, and the acrogynous
Hepaticse, the apical cell of the branch becomes an archegonium,
and a varying number of secondary archegonia arise from its
last-formed segments. The mature archegonium has a mass-
ive basal part and long somewhat twisted neck, consisting of
six rows of cells. As in the other Mosses, the growth of the
young archegonium is apical, and probably as there the neck
canals are formed as basal segments of the apical cell, and the
ventral canal cell is cut off from the central cell in the usual
way. The venter merges gradually into the neck above and
the pedicel below, and at maturity its wall is two or three cells
thick. The egg (Waldner (2)) is ovoid, and the nucleus
shows a distinct nucleolus. AMiether a receptive spot is present
is not stated. Mixed with the archegonia are numerous fine
hairs like those about the antheridium. The leaves immedi-
ately surrounding the group of archegonia later enlarge much
and form a perichcXtium. By the subsequent elongation of
the main axis both archegonial and antheridial branches are
often separated by the growth of the axis between them, al-
though at first they are always crowded together at the top of
the main stem.

The Sporophyte

Waldner (2) has recently studied carefully the develop-
ment of the embryo of Sphagnum, which differs essentially from
all the other Mosses, and has its nearest counterpart in the
Anthocerotes. In the species ^S. aaitifoUnm, mainly studied by
Waldner, the sexual organs are usually mature in the late au-
tumn and winter, and fertilisation occurs early in the spring.
The ripe sexual organs are found in a perfectly normal condi-
tion in mid-winter, under the snow, and apparently remain in
this condition until the first warm days, when they open and
fertilisation is effected. The first embryos were found late in
February, and development proceeded from that time.

The first division in the embryo is horizontal and divides it
into two cells. In the lower of these the divisions are irregu-
lar, but in the upper one the cell walls are arranged with much
regularity. The upper cell is the apical cell of the young em-
bryo, and from it, by walls parallel to the base, a series of seg-

V. MOSSES (MUSCI): SPHAGNALES—ANDRE^ALES i79

ments is formed (Fig. 92, A). These are usually about seven
in number, and each of these segments undergoes regular divi-
sions, these beginning in the lower ones and proceeding toward
the apical cell, which finally ceases to form basal segments and
itself divides in much the same way as the segments. The
latter first divide by two vertical divisions into c[uadrants, and
in each quadrant either directly by periclinal walls, or by an
anticlinal wall followed by a periclinal wall in the inner of the
two cells (Fig. 92, E), four central cells in each segment are
separated from four or eight peripheral ones. The terms en-
dothechim and aniphithccium have been given respectively to
these two primary parts of the young Moss-sporogonium. By
the time that the separation of endothecium and amphithecium
is completed, a division of the embryo into two regions becomes
manifest (Fig. 92, C). Only the three upper segments, in-
cluding the apical one, give rise to spores ; the lower segments
together with the original basal cell of the embryo form the
foot, which in Sphagnum is very large. The cells of the foot
enlarge rapidly and form a bulbous body very similar in appear-
ance and function to that of Notothylas or Anthoceros. The
next divisions too in the upper part of the sporogonium find
their nearest analogies in these forms. The central mass of
cells, both in position and origin, corresponds to the columella
in these genera, and the archesporium arises by the division of
the amphithecium into two layers by tangential walls, and the
inner of these two layers, in contact W'ith the columella, becomes
at once the archesporium. By rapid cell division the upper
part of the sporgonium becomes globular, and is joined to the
foot by a narrow neck, much as in Notothylas (Fig. 93). The
single-layered wall of the young sporogonium becomes six or
seven cells thick, and the columella very massive. The one-
layered archesporium also divides twice by tangential walls,
and thus is four-layered at the time the spore mother cells sep-
arate. All the cells of the archesporium produce spores of the
ordinary tetrahedral form. The so-called ''microspores" have
been shown conclusively to be the spores of a parasitic fungus
(Nawaschin (i)). The layer of cells in immediate contact
with the archesporium on both inner and outer sides has more
chlorophyll than the neighbouring cells, and forms the
*'spore-sac."

i8o

MOSSES AND FERNS

CHAP.

The ripe capsule opens by a circular lid which is indicated
long before it is mature. The epidermal cells where the open-
ing is to occur grow less actively than their neighbours, and
thus a groove is formed which is the first indication of the oper-
culum. The cells at the bottom of the groove have thinner

walls than the other cells
of the capsule wall, and
when it ripens these dry
up and are very readily
broken, so that the oper-
culum is very easily sep-
arated from the dry cap-
sule. Stomata, according
to Schimper, always are
present, sometimes in
great numbers ; but Hab-
erlandt ((4), p. 475 )>
states that these are al-
ways rudimentary, and
he regards them as re-
duced forms. No seta is
formed, but its place is
taken physiologically by
the upper part of the axis
of the archegonial branch,
which grows up beyond
the perichaetium, carrying
the ripe sporogonium at
its top (Fig. 91, E). The
upper part of this "pseu-
dopodium" is much en-
larged, and a section through it shows the bulbous foot of the
capsule occupying nearly the w^hole space inside it. The ripe
capsule breaks through the overlying calyptra, the upper part
of which is carried up somewhat as in the higher Mosses, while
the basal part together with the upper part of the pseudopodium
forms the *'vaginula."

The disorganised contents of the canal cells, which are
usually ejected from the archegonium, in Sphagnuin remain in
a large measure in the central cavity, and on removing the

Fig. 93. — Median longitudinal section of a
nearly ripe sporogonium of 5". acuti foli-
um, X24; ps, pseudopodium; sp, spores;
col, columella (after Waldner).

V. MOSSES (MUSCI): SPHAGNALES—ANDRE^ALES i8i

young embryo from the venter of the archegonium, this muci-
laginous mass adheres to it and forms a more or less complete
envelope about it, in which are often found the remains of
spermatozoids.

The species of Sphagnum are either monoecious or dioecious,
but in no cases do archegonia and antheridia occur upon the
same branch.

The Andre^ales

The second order of the Mosses includes only the small
genus Andrecca, rock-inhabiting Mosses of small size and dark

Fig. 94. — Andrecsa petrophila. A, Plant with ripe sporogonium, Xio; B, median sec-
tion of nearly ripe capsule, X8o; ps, pseudopodium; col, columella.

brown or blackish colour. In structure they are intermediate
in several respects between the Sphagnales and the Bryales,
as has been shown by the researches of Kiihn ( i ) , and Wald-
ner (2), to whom we owe our knowledge of the life-history of
Andrecea. They all grow in dense tufts upon silicious rocks,

i82 MOSSES AND FERNS chap.

and are at once distinguished from other Mosses by the dehis-
cence of their small capsules. These, like those of Sphagnum,
are raised upon a pseudopodium, and are destitute of a true
seta. The capsule opens by four vertical slits, which do not,
however, extend entirely to the summit (Fig. 94). This
peculiar form of dehiscence recalls the Jungermanniaceae, but is
probably only an accidental resemblance. The closely-set stems
branch freely; the leaves, with three-eighth divergence, are
either with a midrib {A. riipcstris) or without one {A.
pctrophila).

The growth of the stem is from a pyramidal apical cell, as
in Sphagnum, and probably the origin of the branches is also
the same as in that genus. The growth of the young leaves is
usually from a two-sided apical cell, but another type of growth
is found where the apical cell is nearly semicircular in outline,
and segments are cut off from the base only. These two forms
of apical growth apparently alternate in some instances in the
same leaf. The originally thin walls of the leaf cells later be-
come thick and dark-coloured, whence the characteristic dark
colour of the plant.

The stem in cross-section shows an almost uniform struc-
ture, and no trace of'the central conducting tissue of the higher
Mosses can be found. The outer cells are somewhat thicker-
w^alled and darker-coloured, but otherwise not different from
the central ones. Numerous rhizoids of a peculiar structure
grow from the basal part of the stem, and from these, new
branches arise, which replace the older ones as they die away.
These rhizoids are not simple rows of cells as in the Bryales,
but are either cylindrical masses of cells or flattened plates.
They penetrate into the crevices of the rocks, or apply them-
selves very closely to the surface, so that the plants adhere
tenaciously to the substratum (Ruhland (2)).

Spores and Protoncma

The germination of the spores and the development of the
protonema show numerous peculiarities. The spores may
germinate within a week, or sometimes remain unchanged for
months. They have a thick dark-brown exospore and contain
chlorophyll and oil. The first divisions take place before the
exospore is ruptured, and may be in thrae planes, so that the

MOSSES (MUSCI): SPHAGN ALES— ANDRE JEALES 183

young protonema then has the form of a glohular cell mass
(Fig. 95, A). This stage recalls the corresponding one in
many of the thallose HepaticcX, e. g., Pellia, Radiila, and is
entirely different from the direct formation of the filamentous
protonema of most Mosses. Some of the superficial cells of
this primary tubercle grow out into slender filaments, either
with straight or oblique septa, and these later ramify exten-
sively. Where there are crevices in the rock, some of these
branches grow into them as colourless rhizoids. but, as in the
Bryales, there is no real morphological distinction between
rhizoid and protonema. Most of the filamentous protonemal
branches do not remain in this condition, but become trans-
formed into cell plates or cylindrical cell masses, like the stem-

-S^^fe

Fig. 95. — A, B, Germinating spores of A. peirophila, X200; C, protonema with bud
(fe) ; D, young archegonium in optical section; E, i, 2, two views of a very young
embryo of A. crassinerva, X266; F, somewhat older embryo of A. petrophila ; G,
older embryo showing the first archesporial cells; H, I, cross-sections of young
embryos, X200. A-D, after Kuhn; E-I, after Waldner.

rhizoids. The flat protonema recalls strongly that of SpJiag-
nwn, and is probably genetically connected with it. All of the
different protonemal forms, except what Kiihn calls the ''leaf-
like structures," vertical cell surfaces of definite form, can give
rise to the leafy axes. The development of these seems to cor-
respond exactly with that of the other Mosses, and will not be
further considered here.

i84 MOSSES AND FERNS chap.

The Sexual Organs *

The species of Andrccca may be either moncecious or dioe-
cious. Archegonia and antheridia occur on separate branches,
but their origin and arrangement are identical. The first-
formed anthericHum develops directly from the apical cell of the
shoot, and the next older ones from its last-formed segments,
but beyond this no regularity can be made out. In the first one
the apical cell projects, and its outer part is separated from the
pointed inner part by a transverse wall. This is followed by a
second wall parallel to the first, so that the antheridium rudi-
ment is composed of three cells. Of these the l(^wer one takes
little part in the future development. Of the two upper cells
the terminal one becomes the body of the antheridium, the other
the stalk. In the former, by two inclined walls, a two-sided
apical cell is developed, and the subsequent growth is the same
as in the Bryales. The middle cell of the antheridium rudi-
ment divides repeatedly by alternating transverse and longi-
tudinal walls, and forms the long two-rowed stalk of the mature
antheridium. On comparing the antheridium with that of the
' other Alosses, we find that it approaches Sphagnum in the long-
stalk, but in its origin and the growth of the antheridium itself,
it resembles closelv the hio-her Mosses.

The first archegonium also is derived immediately from the
apical cell of the female branch, and the first divisions are the
same as in the first antheridium. Here, too, the subsequent
development corresponds exactly with that of the higher
Mosses, and will be passed over. The ripe archegonium shows
no noteworthy peculiarities, and closely resembles in all respects
that of the other Mosses.

The Sporophyte

The more recent researches of Waldner (2) on the develop-
ment of the sporogonium of Andreara have shown clearly that
in this respect also the latter stands between the Sphagnacese
and the Bryales. The first division in the fertilised ovum is
transverse and divides it into two nearly equal parts. The
lower of these divides irregularly and much more slowly than
the upper one. In the latter (Fig. 95, E), the first division
wall is inclined, and is followed by a second one which meets
it nearly at right angles, and by walls inclined alternately right

V. MOSSES (MUSCI): SPHAGNALES—ANDRE^ALES i8s

and left — in short, has the character of the famiHar ''two-sided"
apical cell. The number of segments thus formed ranges from
eleven to thirteen. Each segment is first divided by a vertical
median wall into equal parts, so that a cross-section of the
young embryo at this stage shows four equal quadrant cells.
The next divisions correspond to those in Sphagunuh and result
in the separation of the endothecium and amphithecium. The
formation of the archesporium, however, differs from Sphag-
mini, and is entirely similar to that of the higher Mosses. In-
stead of arising from the amphithecium as in the former, the
archesporium is formed by the separation of a single layer of
cells from the outside of the endothecium. All of the segments
do not form spores, but only three or four, beginning with the
third from the base. The two primary segments of the upper
part of the embryo, like the corresponding ones in SpJiagmim,
go to form the foot, which is not so well developed, however,
as in the latter. The originally one-layered archesporium later
becomes double, and as in Sphagnum extends completely over
the columella, which is thus not continuous with the tissue of
the upper part of the sporogonium. As in Sphagnum also, no
trace of the intercellular space formed in the amphithecium of
the Bryales can be detected. A section of the nearly ripe cap-
sule shows the club-shaped columella extending nearly to the
top of the cavity. With the growth of the capsule the space
between the inner and outer spore-sacs becomes very large to
accommodate the growth of the numerous spores. The pseu-
dopodium is exactly the same as in Sphagnum, and the vaginula
and calyptra are present. The latter is much firmer than in
Sphagnum, and like that of the Bryales.

Archidium

The genus Archidium is one.whose systematic position has
been long a subject of controversy. It has usually been associ-
ated with the so-called cleistocarpous Bryales, but the researches
of Leitgeb (8) seem to point to a nearer affinity with Andrccca.

The species of Archidium are small Mosses growing on the
earth, and especially characterised by the small number, but
very large size, of the spores contained in the sessile globular
sporogonium. Hofmeister ( ( i ) , p. i6o) , was the first to study
the development, and his account agrees in the main with Leit-

1 86

MOSSES AND FERNS

CHAP.

geb's, except as to the relation of the columella and outer spore-
sac. The first divisions in the embryo correspond exactly to
those in Andrccra and the Bryales, and for a time the young
embryo grows from a two-sided apical cell. The secondary
divisions in the segments, however, are quite different from that
observed in any other Moss, and are like those in the anther-
idium. Instead of the first wall dividing the segment into
equal parts, it divides it very unequally. The second wall
strikes this so as to enclose a central cell, triangular in cross-

FiG. 96. — Archidium Ravcnclii. A, Median section through a nearly ripe sporogonium,

X90; B, base of the sporogonium, X270.

section, which with the corresponding cell of the adjacent seg-
ment forms a sc^uare. This square, the endothecium, does not
therefore at first show the characteristic four-celled stage found
in all other Mosses. The amphithecium becomes ultimately
three-layered, and between the second and third layers an inter-
cellular space is formed, as in the Bryales, but this extends com-
pletelv over the top of the columella. The most remarkable
feature, however, is that no archesporium is difYerentiated, but
any cell of the endothecium may apparently become a spore

V. MOSSES (MUSCI): SPHAGNALES—ANDRE^ALES 187

mother cell. The number of the latter is very small, seldom
exceeding five or six. They become rounded off, and gradu-
ally displace the other endothecial cells, which doubtless serve
as a sort of tapetum for the nourishment of the growing spores.
Each spore mother cell as usual gives rise to four spores, which
are very much larger than in any other Moss. A section of
the ripe sporogonium (Fig. 96), shows that only one of the
primary three layers of amphithecial cells can be recognised
except at the extreme apex and base. No seta is present, and
a foot much like that of Andrecca, and penetrating into the tis-
sue of the stem apex, is seen.

Leitgeb is inclined to look upon Archidium as a primitive
form allied on the one hand to Andrecca and on the other to
the Hepaticce, possibly Notothylas. However, as his assump-
tion that the latter has no primary columella has been shown to
be erroneous, his comparison of the whole endothecium of Ar-
chidium with that of Nofothylas cannot be maintained, as we
have shown that in the latter, as in Anthoceros, the arche-
sporium arises from the amphithecium, and not from the en-
dothecium, as is the case in Archidiiim. Inasmuch as the game-
tophyte and sexual organs of Archidium are those of the typical
Mosses, it seems quite as likely that the older view that Ar-
chidium is a degenerate form is correct. At any rate, until
more convincing evidence can be brought forward in support
of a direct connection between it and the Hepaticae than the
formation of the spores directly from the central tissue of the
sporogonium, it cannot be said that the question of its real affin-
ities is settled.

CHAPTER VI

THE BRYALES

Under the name Brvales may be included all the other ]\Iosses ;
for although the so-called cleistocarpous forms are sometimes
separated from the stegocarpuus Mosses as a special order, the
Phascaceae, the exact correspondence in the development of
both the gametophyte and sporophyte shows that the two groups
are most closely allied, the former being either rudimentary or
degraded forms of the others.

With few exceptions the protonema is filamentous and
shows branches of two kinds, the ordinary green ones with
straight transverse septa, and the brown-walled rhizoids with
strongly oblique ones, but the two forms merge insensibly into
one another, and are mutually convertible. In a few forms,
notably the genus TcfrapJiis, the protonema is thalloid, and as
in SpJiag]iuj]i these flat thalli give rise to filamentous proto-
nemal threads, which in turn may produce secondary thalloid
protonemata. The genus Diphysciuin (C. ]\luller (3), pp.
169, 170), develops upon the protonema solid, trumpet-shaped
bodies. In some of the simpler forms, c. g., Ephcincniin, the
protonema is permanent, and the leafy buds appear as append-
ages of it ; but in most of the larger Mosses the primary proto-
nema only lives long enough to produce the first leafy axes,
which later give rise to others by branching, or else by second-
ary protonemal filaments growing from the basal rhizoids.
The early stages of development of the primary protonema are
easily traced, as the spores of most Mosses germinate readily
when placed upon a moist substratum. The ripe spores usually
contain abundant chlorophyll and oil, and the thin exospore is
brown in colour. The spore absorbs water and begins to en-
large until the exospore is burst, when the endospore protrudes

188

CH. VI.

THE BRYALES

189

as a papilla which grows out into a filament ; or the endospore
sometimes 'grows out in two directions, and one of the papill?e
remains nearly destitute of chlorophyll and forms the first rhi-
zoid. The growth of the protonemal filaments is strictly
apical, no intercalary divisions taking place except those by
which lateral branches arise. If abundant moisture is present,
the protonema grows with great rapidity and may form a dense
branchinof al^'a-like growth of considerable extent. Sooner or
later upon this arise the leafy gametophores. The develop-
ment of the latter, as we have seen, also takes place abundantly

Fig. 97. — Funaria hygrometrica. A, Fragment of a protonemal branch with a young
gametophoric bud; r, rhizoid; B, median optical section of the bud; C, older bud — •
I, surface view; 2, optical section; .v, apical cell; U, protonema with a still older
gametophore {gam) attached. A-C, X-225; D, X36.

from the secondary protonemal filaments which may be made to
grow from almost any part of the gametophore.

The development of the bud is as follows. From a cell of
the protonema a protuberance grows out near the upper end.
This is at first not distinguishable from a young protonemal
branch, but It very soon becomes somewhat pear-shaped, and
instead of elongating and dividing simply by transverse walls,
the division w^alls intersect so as to transform it into a cell mass.

iQO MOSSES AND FERNS chap.

After the cell is separated it is usually divided at once by a
strongly oblique wall, which is then intersected by two others
successively formed and meeting each other and the first-formed
one at nearly equal angles, so that the terminal cell of the young-
bud (Fig. 97, A), has the form of an inverted pyramid; that
is, by the first divisions in the bud the characteristic tetrahedral
apical cell of the gametophore is established. From now on
the apical cell divides with perfect regularity, cutting off three
sets of lateral segments. From the base of the young gameto-
phore the first rhizoid (Fig. 97, A, r), is formed at a very early
period. The first two or three segments do not give rise to
leaves, and the leaves formed from the next younger segments
remain imperfect. Thus in Funaria hygrometrica these earliest
formed leaves show no midrib. The young leaves rapidly
elongate and completely cover up the growing point of the
young bud, and are at first closely imbricated. Later, by the
elongation of the axis, the leaves become more or less completely
separated (Fig. 97, C, D). In Funaria, as well as in many
other Mosses, buds are often met with that have become arrested
in their development, lost their chlorophyll, and assumed a dark-
brown colour. This arrest often seems to be the result of un-
favourable conditions of growth, and under proper conditions
these buds probably always will develop either directly or by
the formation of a secondary protonema into perfect plants.

Apical Grozvfh of the Stem

The growth of the stem of the fully-developed gametophore
is better studied in one of the larger Mosses. The growth of
the gametophore is so limited in length in Funaria that it is
not so well adapted for this. Perhaps the best species for this
purpose is the well-known Fonfinalis antipyretica, which has
already been carefully studied by Leitgeb ( i ). Anihlysfcgiuni
ripariuni, var. fliiitans, was examined by me and differed in
some points from Leitgeb's figures of Fontinalis. Fig. 98, A
shows an exactly median longitudinal section through a strong
growing point. Compared with Leitgeb's figures the apical cell
is much deeper than in Fontinalis, and in consequence the young
segments more nearly vertical. Here, as in Sphagnum, the first
wall in the voung^ secrment divides it into an inner and an outer
cell, from the latter of which alone are formed the lateral

VI.

THE BRYALES

191

appendages of the stem. The inner cehs of the segments by
repeated longitudinal and transverse divisions form all the tis-
sues of the axis. The second division wall in the segment, like
that in Sphagnum, is at right angles to the first, but in Ambly-
stegium it extends the whole breadth of the segment. By this
division the outer of the two primary cells of the segment is
divided into an upper cell, from which the leaf develops, and a
lower one from which the outer part of the stem and the buds
are formed. The leaves grow from a two-sided apical cell

Fig. 98. — Amhlystegium riparium, var. fluitatts. A, Median longitudinal section of a
strong shoot; x, apical cell; x', initial of a lateral branch, X250; B, transverse
section through the apex, X250; C, similar section through a young branch, X500.

(Fig. 99), as indeed they seem-to do in all Mosses, and the
divisions proceed with great rapidity and the young leaves
quickly grow beyond and surround the growing point. In
Amhlystegium, as in all the typical Bryales, the leaf has a well-
developed midrib. The formation of this begins while the leaf
is very young and proceeds from the base. In the middle row
of cells (Fig. 99, C), a wall first arises parallel to the surface
of the leaf, and this is followed by a wall in the cell on the lower
side of the leaf (Fig. 99, D). By further divisions in all the

192

MOSSES AND FERNS

CHAP.

cells of this central strand the broad midrib found in the mature
leaf is developed. In Amhlysteguun all the cells of the midrib
are alike and have thickened walls. The midrib projects on both
sides of the leaf, but rather more strongly upon the lower side.
In Funaria (Fig. loo), the structure of the midrib is more
definite. Here two rows of cells take part in the formation of
the midrib. Each of these first divides as in Ainhlystcginm by
a wall parallel to the surface of the leaf, so that in cross-section
the central part of the leaf shows a group of four cells, those

Fig. 99. — Amhlystcgium riparium, var. iluitans. A, Longitudinal section of the stem
passing through a young lateral branch (A-) ; U, hair at the base of the subtending
leaf; B, horizontal section of a very young leaf, showing the apical cell (.r) ; C,
D, transverse sections of young leaves, showing the development of the midrib.
All the figures XS2S.

on the outer side being larger than the others. In the former
the next wall is a periclinal one and divides the cell into an inner
and an outer one. From the two inner cells by further division
is formed the group of small conducting cells that traverse the
centre of the midrib, while the outside cells toe:ether with those
on the inner side of the midrib become much thickened and
serve for strengthening the leaf. As in Aiuhlystcgimn the
lamina of the leaf remains single-layered, and its cells contain
numerous large chloroplasts which, as is well-known, continue

VI.

THE BRYALES

.193

to multiply by division after the cells are fully grown. The
marginal cells in the leaf of Funaria are much narrower than
those between them and the midrib, and their forward ends

Fig. 100. — Funaria hysrometrica. A, Transverse section of the apex of a young shoot,
X515; B, C, cross-sections of young leaves, X515; D, cross-section of the stem,
X257.

often project somewhat, giving the margin of the leaf a serrate
outline, which is also common in many other Mosses.

The Branches

For the study of the branching of the stem, Amblysteginm
again is much better than Funaria, whose short stem and infre-
quent branching makes it difficult to find the different stages.
In Amhlystegium, however, every median section will show
some of the stages, and it is easy to follow out all the details,
as has already been done in Fontinalis by Leitgeb. The lateral
shoot originates from a basaf cell of the segment below the
middle of the leaf. It is very easily seen that it belongs to the
13

194 MOSSES AND FERNS chap.

same segment as the leaf standing above it, and therefore is
not axillary in its origin. The mother cell of the young branch
projects above the surrounding cells, and in it are formed in
succession three oblique intersecting walls which enclose the
narrow pyramidal apical cell (Figs. 98, 99). The secondary
divisions in the first set of segments are not so regular as in
the later on^s, but the bud rapidly grows, and very soon the
perfectly regular divisions of the young segments are estab-
lished. So far as investigations have been made upon other
genera, they follow the same line of development as Aiiibly-
stcgiuui, Fojitiiialis, and SpJiagniDii.

\Miere the growth of the main axis is stopped by the form-
ation of sexual organs, a lateral branch frequently grows out
beyond the apex of the main axis, as in SpJiagnuDi, and thus
sympodia arise. In other cases, where the growth of the lat-
eral branches is limited, characteristic branch systems arise,
such as we find in Thuidhiui or Cliniaciuni (Fig. 86).

Compared with Aniblystcgiuni, the growing point of
Fuuaria and other flosses of similar habit is much broader,
and the apical cell not so deep. The arrangement of the
segments is much the same, except that the original three -
ranked arrangement of the segments which is retained in Fonti-
nalis^ is replaced in most Mosses by a larger divergence, owing
to a displacement like that in SpJiagJium.

A cross-section of the older stem (Fig. 100, D), shows in
most Bryales a central cylinder of small thin-walled cells sur-
rounded by a large-celled cortical tissue, which in the older
parts of the stem often has its walls strongly thickened and
reddish brown in colour. An epidermis, clearly recognisable
as such, cannot usually be detected. The outer cells contain
chlorophyll, which is wanting in the central cylinder.

The rhizoids in Funaria grow mainly from the base of the
stem, and the first ones arise very soon after the young bud is
formed. Their growth, like that of the protonemal branches,
is strictly apical, and they branch extensively. The young ones
are colourless, but as they grow^ older the walls assume a deep
brown colour. Usuallv the division walls in the rhizoids are
strongly oblique. Their contents include more or less oil, and
where they are exposed to the light, chlorophyll.

^This is only strictly true in the smaller branches.

VI.

THE BRYALES

195

The Sexual Organs

Funaria is strictly dioecious. The male plants (Fig. 1 01,
A) are easily distinguished by their form. They are about i
cm. in height, with the lower leaves scattered, but the upper

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ones crowded so as to present much the appearance of a flower
whose centre forms a small reddish disc. These male plants
either grow separately or more or less mixed with the females.

196

MOSSES AND FERNS

CHAP.

Whether the first antheridium, as in Andrccca and Fontinalis,
arises from the apical cell is doubtful, and it is impossible to
trace any regularity in the order of formation of the \ery
numerous antheridia. Except in old plants, all stages of de-
velopment are found together, and the history of the anther-
idium may be easily followed. A superficial cell projects above
its neighbours, and this papilla is cut off by a transverse wall.

Fig. 102. — Funaria hygrometrica. Development of the antheridium. A-D, Longitudinal
sections of young stages, X600; D is cut in a plane at right angles to C; E, optical
section of an older stage, X300; G, F, cross-sections of young antheridia, X600;
H, diagram showing the first divisions in the antheridium; I, young spermatozoids,
X 1200.

The outer cell either becomes at once the mother cell of the
antheridium, or other transverse walls may occur, so that a
short pedicel is first formed (Fig. 102, A). Finally in the
terminal cell, as in Andrecea, two intersecting w^alis are formed
enclosing a two-sided apical cell, from which two ranks of seg-
ments are cut off in regular succession (Figs. A, B, C). The
number of these segments is limited, in Funaria not often ex-
ceeding seven, and after the full number has been formed, the

VI.

THE BRYALES J97

apical cell is divided by a septum parallel with its outer face
into an inner cell, which wath the inner cells of the segments
forms the mass of sperm cells, and an outer cell which produces
the upper part of the wall. Before the full number is com-
pleted, the secondary divisions begin, proceeding from the base
upward. These are very regular, and correspond closely to
those in the antheridium of the Jungermanniaceae, and can only
be clearly made out by comparing transverse and vertical sec-
tions of the young antheridium. Fig. 102, H, shows a diagram
illustrating this: i is the wall separating two adjacent seg-
ments, and 2 the first wall formed in the segment itself. The
wall 2, it will be seen, starts near the middle of the periphery
of the segment and strikes the wall i far to one side of the
centre, so that the segment is thus divided into two cells of very
unequal size, although their peripheral extent is nearly equal.
The next wall (3) strikes both the wall i and 2 at about equal
distances from the periphery, and thus each segment is divided
into an inner cell wdiich in cross-section has the form of a tri-
angle, and two peripheral cells. The latter divide only by
radial walls, and give rise to the single-layered wall of the
antheridium. The inner cells of the segments by further di-
vision in all directions form the mass of sperm cells. The first
division wall in the central cell starts from near the middle of
the segment wall and curves slightly, so that the two resulting
cells are unequal in size. From this first division wall usually
two others having a similar form extend to the peripheral cells,
and these are next followed by others nearly at right angles
to them. After this transverse and longitudinal walls succeed
with such regularity that the limits of the primary segments
remain perfectly evident until the antheridium is nearly full
grown.

The central cells in the fresh antheridium are strongly re-
frin^ent and in stained sections ^show a much more granular
consistence than the outer ones. The nucleus, as in other cases
studied, loses its nucleolus before the formation of the sperma-
tozoids begins. The latter in their structure and development
correspond with those of Sphagnum, but owing to their smaller
size are not favourable for studying the minute details of de-
velopment.

In the peripheral cells are numerous chloroplasts which in
the ripe antheridium lie close to the inner wall of the cell. As

198

MOSSES AND FERNS

CHAP.

the antheridium ripens, these gradually assume a bright orange-
red colour. The development of the stalk varies in different
cases. Sometimes it consists of a row of several cells, some-
times the antheridium is almost sessile. The lowermost see-

Fig. 103. — Funaria hygrometrica. A, Antheridium that has just discharged the mass
of sperm cells (B), X300; C, spermatozoids, X1300; D, paraphysis, X300; E,
male "flower" of Atrichum undulatum, X6.

ments of the apical cell help to form the upper part of the
stalk, and sometimes the two lowest seem to take no part in the
formation of the sperm cells. There is no absolute uniformity
in the cell divisions of the stalk, which varies in the arrange-

n. THE BRYALES I99

ment of the cells in different individuals in the same inflor-
escence.

The ripe antheridium opens promptly when placed in water.
At the apex there is usually present a single cell decidedly
larger than its neighbours (Fig. 103, A), or sometimes there
are two opercular cells (Goebel {22), p. 239). All of the
parietal cells become strongly turgescent and this is especially
the case in the terminal cell, which finally bursts and forms a
narrow opening through which the mass of sperm-cells is forced
out by the pressure of the distended parietal cells, and the swell-
ing of the mucilage derived from the disintegration of the walls
of the sperm-cells. The opercular cell in Fiinaria is not de-
stroyed, as a rule, and is still very conspicuous after the sperm-
cells have been discharged, so that the empty antheridium, ex-
cept for a slight contraction of its lower part, looks very much
as it did before the escape of the sperm-cells. In some other
Mosses, e. g., Polytrichum, Catharinia, the opercular cap con-
sists of several cells (Goebel, 1. c). The whole mass of sperm-
cells is thrown out without separating the cells, and in this
stage the walls of the sperm-cells are still very evident. It
sometimes happens that the mass is thrown out before the
spermatozoids are complete, in which case they never escape.
If, however, the spermatozoids are mature, they show active
motion within the sperm-cells while these are still in connection,
and are set free by the gradual dissolution of the mucilaginous
walls. The free spermatozoid is much like that of Sphagnum,
but the body is somewhat shorter. The cilia are relatively
very long and thick, and as in all Bryophytes but two in num-
ber. A small vesicle can usually be seen attached to the pos-
terior end.

Growing among the antheridia are found peculiar sterile
hairs, or paraphyses. These in Funaria are very conspicuous,
and consist of a row of cells tapering to the base, and very
much larger at the apex. The terminal cell, or sometimes two
or three of them, are almost globular in form and very much
distended. All the cells of the paraphyses contain large
chloroplasts, which in the globular end cells are especially con-
spicuous and are often elongated with pointed ends.

The archegonia are formed while the female plant is still
very small, and it is much more difficult to recognise the female
plants than the males. The archegonia are ripe at a time when

200

MOSSES AND FERNS

CHAP.

the female plant is still but a few millimetres in height. In this
case there is no doubt that the apical cell forms an archegonium
directly, but not necessarily the first one, which arises usually
from one of the last-formed segments. The elongation of the
axis of the female branch is but slight, even in the later stages,

Fig. 104. — Longitudinal section through the apex of a male plant of F. hygrometrica,

X300; L, leaf; (^, anther idia; p, paraphyses.

and the plant remains bud-like even after the sporogonium is
developed. In regard to the development of the leafy axis, or
gametophore, therefore, Funaria offers a very marked contrast
to Fontinalis or Sphagmiin, where the gametophore reaches
such a large size and has practically unlimited growth.

The young archegonia are quite colourless, and the details

VI.

THE BRYALES

201

of their structure may be made out without difficulty. The
first division separates a basal cell from a terminal cell, which
is the mother cell of the archegonium. In the latter three walls

now arise, as in the Hepaticse and AndrecBa, but in Funaria
these do not all reach to the basal wall, but intersect at some
distance above it, so that they enclose a tetrahedral cell, pointed

202 MOSSES AND FERNS chap.

below instead of truncate. The tetrahedral cell now divides
by a transverse wall into an upper cell, corresponding to the
''cover cell" of the Liverwort archegonium, and an inner one
(Fig. 105, A), which gives rise to the primary neck canal cell,
the Qgg, and the ventral canal cell. From this point, however,
the development proceeds in another way, and follows the
course observed in Andrccca. The cover cell, instead of divid-
ing by quadrant walls, has a regular series of segments cut off
from it, and acts as an apical cell. These segments are cut off
parallel both to its lateral faces and base, and thus form four
rows of segments, the three derived from the lateral faces
forming the outer neck cells, and the row of segments cut oft'
from the base constituting the axial row of neck canal cells.
Each row of lateral segments is divided by vertical walls, and
forms six rows, which later divide by transverse walls as well
so that the number of cells in each row exceeds the original
number of segments. This is not the case with the canal cells,
which, so far as could be determined, do not divide after they
are first formed. The wall of the venter owes its origin en-
tirely to the three peripheral cells formed by the other primary
walls in the archegonium mother cell. This becomes two-lay-
ered before the archegonium is mature, and is merged gradu-
ally into th.e massive pedicel, which in the Mosses generally is
much more developed than in the Hepaticse. In the older
archegonia the neck cells do not stand in vertical rows, but are
somewhat obliquely placed, owing to a torsion of the neck dur-
ing its elongation. From the central cell the ventral canal cell
is cut off, as usual, but is relatively smaller than is usual among
the Hepaticae. The ^gg shows a distinct receptive spot, which
is not, however, very large. The rest of the tgg shows a
densely granular appearance, and the moderately large nucleus
shows very little colourable contents, beyond the large central
nucleolus. The terminal cells of the open archegonium diverge
widely, giving the neck of the archegonium a trumpet shape
(Fig. 105, F). Usually some of the cells become detached and
are thrown off.

Holferty (i) has made a careful study of the archegonium
in Mniiiiu cuspidatum and finds that the archegonium in its
earliest stages grows from a two-sided initial cell like that of
the antheridium. This is later replaced by the usual tetra-
hedral apical cell found in other species. After a more or less

VI.

THE BRYALES 203

massive pedicel is formed, the apical cell divides, as in Fiinaria,
into an inner and an outer cell. The former, as usual, gives
rise to the central cell, from which later arise the egg and ven-
tral canal cell, and a second cell, which is the primary neck
canal cell. The latter, according to Holferty, undergoes fur-
ther divisions and the secondary canal cells, cut off from the
base of the apical cell, also undergo further divisions. There
may be as many as ten neck canal cells finally developed.

Holferty also describes and figures several abnormal struc-
tures, intermediate in character between the archegonium and
antheridium.

While in Fimaria and Polytrichiim the plants are regularly
dioecious, in many Mosses this is not the case. Both antheridia
and archegonia may occur in the same ''inflorescence," or they
may be in separate groups upon different parts of the same
plant. Some doubt has been thrown upon the nature of the so-
called hermaphrodite inflorescences, and it is possible that they
are really composed of distinct but closely approximated inflor-
escences. (Satter (2) ; see Ruhland (i), pp. 204, 205.)

The Sporophyte

The first (basal) wall in the fertilised ovum divides it into
an upper and lower cell, as in Sphagnum and Andrecua, and the
next divisions correspond closely to those in the latter. In both
cells a wall is formed intersecting the basal wall, but not at
right angles. This is especially the case in the upper cell, where
a second wall strikes the first one nearly at right angles, and
establishes the two-sided apical cell by wdiich the embryo grows
for a long time. In the low^er cell the divisions are somewhat
less regular, but here also it is not uncommon to find a some-
what similar state of affairs, so that the embryo may be said to
have two growing points, although the lower end shows neither
such regiflar nor so active growth as the upper one. In the lat-
ter the divisions follow each other w^ith almost mathematical
precision. There seems to be no rule as to how many segments
are cut off from the apical cell before it ceases to function as
such, but there are more than in Andrecoa, and the embryo
soon becomes extremely elongated. A series of transverse
sections of the young sporogonium shows very beautifully the
succession of the first walls in the young segments. In a sec-
tion just below the apex (Fig. 107, A), each segment is seen to

204

MOSSES AND FERNS

CHAP.

Fig. io6. — Funaria hygrometrica. Development of the embryo. A, Optical section
of a very young embryo; B, C, surface view and optical section of an older one,
X6oo; C, D, longitudinal sections of the apex of older embryos, X6oo; en, endo-
thecium; am, amphithecium.

VI.

THE BRYALES

205

be first divided by a median wall into two equal cells. In
Funaria usually the next division wall is periclinal, and at once
separates endothecium and amphithecium. In most other
Bryinese that have been examined, however, and this may also
occur in Funaria (see Fig. 107, A), the second walls formed in
the young segments are anticlinal, and it is not until the third
set of walls is formed that the separation of endothecium and
amphithecium is complete. The next divisions (Fig. 107, C),
are in the amphithecium, and separate it into two layers. In
the endothecium a series of walls is next formed, almost exactly
repeating the first divisions in the original segment (Figs. D»

Fig. 107. — Five transverse sections of a young embryo of F. hygrometrica. A, Just
below the apex, the others successively lower down; en, endothecium, X450.

E), and transforming it into a group of four central cells and
eight peripheral ones. Each of the latter divides twice by in-
tersecting walls, so that a group of about sixteen cells (Fig.
108, A), occupies the middle ot the endothecium. The eight
peripheral cells divide by radial walls, after which each of these
cells is divided by a periclinal wall into an outer and an inner
cell (Fig. 108, B), and the outer cells divide rapidly by radial
walls and form the archesporium. The single layer of cells
immediately within, and therefore sister cells of the primary
archesporial ones, is the inner spore-sac.

The account of the development of the endothecium here
given differs slightly from the account of Kienitz-Gerloff (2).

206

MOSSES AND FERNS

CHAP.

It was found first that there was not the absolute constancy in
the number of cells given by him; thus in Fig. io8, A there
are only fourteen cells in the inner part of the endothecium,
and although there are sixteen cells in the outer row their
position is not perfectly symmetrical. Again the periclinal
division of the cells of the inner spore-sac takes place later than
he states is the case.

In the eight primary cells of the amphlthecium there first
arise periclinal walls that divide each cell into an inner small
cell in contact with the endothecium, and an outer larger one.

Fig. io8.— Three transverse sections of an older sporogonium of F. hygrometrica, X400;

ar, archesporium; t, intercellular spaces.

This first division separates the wall of the capsule from the
outer spore-sac. The latter next divides by radial and trans-
verse walls, and later by periclinal walls into two layers (Fig.
108). Almost coincident with the latter, the rows of cells
lying immediately outside it show a very characteristic appear-
ance. They cease to divide, and with the rapid growth in
diameter of the capsule become much extended both vertically
and laterally, but are compressed radially. It is between these
cells and the spore-sac that the characteristic air-space found
in the capsule is formed. This is first evident shortly after
the enlargement of the base of the capsule begins. The devel-

VI. THE BRYALES 207

opment can be very easily followed in longitudinal sections
made at this stage. The formation of the space begins at the
base of the capsule and proceeds toward the top. The line of
cells bordering on the spore-sac is very easily followed, owing
to their being so much larger than the neighbouring ones. As
this is followed down, it is found that at the base of the capsule
the cells are separated by large intercellular spaces, which be-
come less marked toward the apex. With the rapid enlarge-
ment of the capsule these spaces become very large, and sec-
tions made a little later show that during this process the cells
remain in contact at certain points, and form short filaments
that extend across the space and unite the wall of the capsule
with the outer spore-sac. At the base of the capsule the for-
mation of intercellular spaces is not confined to the single layer
of cells but involves the whole central mass of tissue, which be-
comes thus transformed into a bundle of filaments connecting
the columella with the basal part (apophysis) of the capsule.
The innermost of the two layers of cells between the arche-
sporium and the air-space finally undergoes a second periclinal
division, and in the full-grown sporogonium the archesporium
is bounded on the outside by three layers of cells.

The differentiation into seta and capsule takes place late
in Ftinaria, and the first indication of this is the enlargement
of a zone between the two, forming the apophysis, which at
this stage (Fig. 109), is much greater in diameter than the
upper part of the capsule. Sections through the apophysis
and seta show a less regular arrangement of the cells than in
the sporiferous part of the capsule, but the general order of
cell-succession is the same, except for the formation of the
archesporium. Almost as soon as the capsule is recognisable,
the first indication of the operculum or lid becomes evident.
About half-way between the extreme apex of the sporogonium
and the top of the apophysis, a shallow depression is noticed
extending completely round the capsule and separating the
sharply conical apex from the part below. An examination of
a longitudinal section at this point shows that at the point of
separation the epidermal cells of the opercular portion are much
narrower than those immediately below. Examining the tis-
sues farther in, the archesporium is seen to extend only to a
point opposite the base of the operculum, and the same is true
of the row of large cells where the air-space is formed. If a

Fig. 109. — Funarta hygrometnca. A, LongitiuHnal section of a sporogonium showing
the first differentiation of its parts, X about 96; B, the upper part of the same,
X600; r marks the limits of the theca and operculum; C, basal part of the cap-
sule of the same, X600. The intercellular spaces are beginning to form; ar,
archesporium; col, columella.

VI.

THE BRYALES

'20^

similar section is made through an older capsule (Fig. no),
it is evident at once that the enlargement takes place mainly
below the junction of the operculum, and there is also a similar
but less pronounced increase in diameter in the operculum itself ;
but there is a narrow zone at the junction of the operculum and
capsule, where the epidermal cells increase but little in depth,
while those above this point become very much larger and pro-
ject beyond them. This narrow zone of cells marks the point
where when ripe the operculum becomes detached. The latter,

Fig. no. — Longitudinal section of an older capsule of F. hygrometrica; i, intercellular
spaces; sp, archesporium; r, cells between operculum and theca, X52S-

up to the time the sporogonium- is ripe, is composed of a close
tissue without any intercellular spaces. The epidermal cells,
seen from the surface, are seen to be arranged in spiral rows
running from the base to the apex. Its central part is made up
of large thin-walled parenchyma, continuous with the tissue of
the columella. The archesporium, therefore, is not continuous
over the top of the columella, as in Sphaguum and Andrecea,
but is cylindrical. The archesporium forms simply a single
layer of small cells, and occupies a very small part of the sporo-
14

2ia

MOSSES AND FERNS

CHAP.

gonium, much less, relatively, than in any of the forms hitherto
described. Before the final division of the spores it divides
more or less completely into two layers. The cells resulting
from this last division are the spore mother cells, which separate
soon after their formation and lie free in the space between the
inner and outer spore-sacs, where each one divides into four
tetrahedral spores.

In the operculum, as the capsule approaches maturity, the
differentiation of annulus and peristome takes place. The
annulus consists of five or six rows of cells that occupy the

Fig. III. — A, Longitudinal sections of a nearly ripe capsule of F. hygrometrica, X260;
per, peristome; r, annulus; t, thickened cells forming the margin of the theca; B,
the sporogenous cells shortly before the final divisions; i, inner; o, outer spore-
sac, X525'

periphery of the broadest part of the operculum. The upper
rows of cells are very much compressed vertically, but are
greatly extended radially and have their walls thicker than those
of the neighlxmring cells. These thickened annulus cells form
the rim of the loosened operculum. The two lower rows of
annulus cells — th.e annulus proper — have thin walls and finally
become extremelv turs:escent. It is the destruction of these

VI.

THE BRYALES

211

cells, when the capsule is ripe, that effects the separation be-
tween the operculum and theca.

The peristome arises from the fifth layer of cells from the
outside of the operculum. If a median longitudinal section of
a nearly ripe capsule is examined, the row of cells belonging
to this layer (Fig. iii, per), is at once seen to have the outer
walls strongly thickened, and this thickening extends for a
short distance along the transverse walls. The inner walls of
the cells also show a slight increase in thickness, but much less
marked than the outer ones. A similar thickening of the cell
walls occurs also in about three rows of cells w^hich run from

Fig. 112. — Longitudinal section of a fully-developed sporogonium of Funaria hygro-
metrica, X about 40; s, seta; a, apophysis; sp, spores; col, columella; r, annulus;
0, operculum.

the outside of the capsule to the base of the peristome, and form
the rim of the "theca" or urn.

The epidermis of the whole capsule has its outer w^alls very
much thickened, and upon the .apophysis are found stomata
quite similar to those found upon the sporogonium of Antho-
ceros or upon the leaves of vascular plants. Haberlandt ( (4),
p. 464), showed that while the form of the fully-developed
stoma in Funaria differs from that of most vascular plants,
this difference is secondary, and that in its earlier stages no
difference exists. This can be easily verified, and with little
difficulty all the different stages found. The young stoma
(Fig. 113), has the division wall extending its whole length,

212

CHAP.

MOSSES AND FERNS
as is the case in stomata of the ordinary form. As the stoma

Fig. 113.— FMMana hygromctrica. A, Young; B, older stoma, from the base of the

capsule; C, vertical section, X360.

grows larger, however, the median wall does not grow as fast
as the lateral walls, and a space is left between its extremities,

Fig. 114. — Funaria hygromctrica. A, Part of the peristome; o, an outer tooth; t, one
of the inner teeth, X85; B, section of the seta, X260; C, cross-section of upper
part of calyptra, X525.

so that the two guard cells have their cavities thrown into
communication, and the division wall forms a cellulose plate

VI. THE BRYALES 213

extending- from the lower to the upper surface of the stoma,
but with its ends quite free. The formation of the pore by
the sphtting of the middle lamella of the division wall takes
place in the ordinary way. Later the walls of the epidermal
cells become very thick and show a distinct striation (Fig.
113). By the formation of the stomata the green assimilat-
ing tissue of the apophysis and central part of the capsule is
put into direct communication with the external atmosphere.

The lower part of the seta grows downward and penetrates
the top of the stem of the gametophyte, from which, of course,
it derives a portion of its sustenance. The centre of the seta
is traversed by a well-marked central cylinder, whose inner
cells are small and thin-walled, and are mainly concerned in
conducting water; immediately outside of this is a circle of
thick-walled brown cells (leptome of Haberlandt), and the
rest of the seta is made up of nearly similar thick-walled cells
which grow smaller toward the periphery.

At maturity, as the supply of water is cut off from below,
the capsule dries up, and all the delicate parenchyma compos-
ing the columella and inner part of the operculum, as well as
that between the spore-sac and the epidermis of the theca, com-
pletely collapses, leaving little except the spores themselves, and
the firm cell wells of the peristome, and the cells connecting
the latter with the wall of the capsule. By the breaking down
of the unthickened lateral and transverse walls of the peri-
stomial cells, the outer and inner thickened walls are separated
and form the two rows of membranaceous teeth that surround
the mouth of the urn (Fig. 114). By the drying up of the
thin-walled cells between the annulus and the margin of the
theca the operculum is loosened and is very easily separated.
The teeth of the peristome are extremely hygroscopic, and
probably assist in lifting off the operculum as well as removing
the spores from the urn. Whea wet they bend inward, extend-
ing into the cavity of the urn. As they dry they straighten
out and lift the spores out. The marked hygroscopic move-
ments of the seta also are no doubt connected with the dissem-
ination of the spores.

The calyptra in the Bryales is very large and is carried
up on the top of the sporogonium in the form of a conspicuous
membranaceous cap. As in other forms it is the venter alone
that shows secondary growth. In Funaria it increases very

214 MOSSES AND FERNS chap.

much in diameter at the base, where it is widened out Hke a
bell, and far exceeds in diameter the enclosed embryo. Above
it is narrow and lies close to the embryo. After a time the
embryo grows more rapidly in length than the calyptra, which
then is torn away by a circular rent about its base, and is
raised on top of the elongating sporogonium. The lower por-
tion remains delicate and nearly colourless, but the upper part
has its cells thick-walled and dark-brown in colour (Fig. 114,
C). Tipping the whole is the persistent dark-brown neck of
the archegonium.

Classification of the Bryales

Cleistocarpcu

The simplest of the Bryales are the Clcistocarpcc or those
in which there is no operculum developed, and in consequence
the capsule opens irregularly. If Archidinni is removed from
this group the simplest form known is Ephemenim. In this
genus, from a highly-developed filamentous protonema are pro-
duced the extremely reduced gametophores. According to
Miiller, (2) who has studied the life-history of this genus,
both male and female branches arise from the same protonema,
and are only distinguishable by the smaller size of the former.
The axis of the branch is scarcely at all elongated, and the leaves
therefore appear close together. The sexual organs corre-
spond closely in origin and structure to the other Bryales. The
development of the sporogonium in its early phases is also the
same, and the differences only appear at a late stage. The
separation of endothecium and amphithecium is apparently ex-
actly the same as in other Bryales, and from the former is de-
rived the archesporium, which like that of Funaria has the form
of a hollow cylinder through which the columella passes. Be-
tween the outer spore-sac and the wall of the sporogonium an
intercellular space is also formed, but the separation of the cells
is complete, and there are no filaments connecting the spore-sac
and the sporogonium wall as in Fiinaria. The cells of the
archesporium are few in number and correspondingly large
(Fig 115, E), and before the division into the spores takes
place all the central tissue of the columella is absorbed, and
the spore mother cells occupy the whole central space, where
the division of the spores is completed, and at maturity the

Wl.

THE BRYALES

215

Fig. 115. — A, Longitudinal section of the young sporogonium of Pleuridium suhulatum,
X80; B, part of the same, X600; sp, archesporium; C, young embryo of Phascurn
cuspidatum, optical section, X175; D, cross-section of an older embryo of the
same, X350; sp, archesporium; E, longitudinal section of the central part of the
young sporogonium of Ephemerum phascoides, X350; sp, archesporium. C, D,
after Kienitz-Gerloff; E, after Miiller.

210

MOSSES AND FERNS

CHAP.

whole of the capsule is filled with the large spores, and no trace
of the columella remains.

Nanoiuitriuni ( Goebel (22), p. 374), closely resembles
Ephoiierum in the development of the sporophyte.

The highest members of the Cleistocarpae, such as Phasciim
and rieiiridiiDu (Fig. 116), approach very closely in structure
the stegocarpous Bryales. In these the gametophore is much
better developed than in Ephcmcriun, and the protonema not
so conspicuous. The leaves also frequently have a well-
developed midrib which is wanting in the leaves of Ephcmeriim.
Kienitz-Gerlofif (2) has carefully studied the embryogeny
of Phascwn cuspidatnm, and except in a few minor details it

corresponds verv closely to that of
Fnnaria, except, of course, as re-
gards the operculum and peristome,
which are absent. In Phascum,
however, the archesporium is dif-
ferentiated earlier than in Fnnaria.
In each of the four primary cells of
the endothecium, as seen in trans-
verse section, a periclinal wall
arises which at once separates the
archesporium from tlie columella
(Fig. 115, D). The outer spore-
sac has but two lavers of cells, and
the capsule wall three, and between
them the large lacuna is formed as
in Fnnaria; but in Phascum as in
Ephcmcrnm, the separation of the
cells is complete. In the seta a
slightly-developed central cylinder of conducting tissue is de-
veloped, derived, as in Fnnaria, from the endothecium, but in
Phascnm it is much less conspicuous. Plenridinm (Fig.
115, A) in its later stages corresponds exactly to Phascnm, ex-
cept that the capsule is more slender. In both of these genera
the seta remains short, but is perfectly evident. Whether the
absence of a distinct operculum in the cleistocarpous Mosses is
a primitive condition, or whether they are reduced forms, it is
impossible to determine positively from a study of their em-
bryogeny.

Fig. 116. — PleuriJium
X20.

subulatum.

VI. THE BRYALES 217

Stegocarpce

Very much the larger number of Mosses belong to this
group, which is primarily distinguished from the foregoing by
the presence of an operculum. Of course among the 7000 or
more species belonging here there are many differences in struc-
ture ; but these are mainly of minor importance morphologically,
and only the more important differences can be considered here.

As we have already seen, there is great uniformity in the
growth of the stem, which, with the single exception of Fis~
sidens, has always a three-sided pyramidal apical cell. In
Fissidens this is replaced by a two-sided one, but even here it
has been found (Goebel (8), p. 371) that the underground

Fig. 117. — Cyathophorum pennatum, showing three rows of leaves; sp, sporophytes,

stems have a three-sided initial cell, which is gradually replaced
by the two-sided one after the apex of the shoot appears above
ground. In Fissidens the leaves are arranged in two rows cor-
responding to the two sets of segments, and are sharply folded,
so that the margins of the leaf are covered over by those of the
next older ones, leaving only the apex free. A similar arrange-
ment is found in the genus Bryoziphion (Eiistichia) , but here
there is a three-sided apical cell, and the two-ranked arrange-
ment of the leaves is secondary. In Cyathophorum (Fig. 117),
there are two rows of large dorsal leaves and a row of much

2i8 MOSSES AND FERNS chap.

smaller ventral ones, so that the plant resembles very closely a
foliose Liverwort. The curious genus Schistosfega shows also
a two-ranked arrangement of the leaves of the sterile branches,
but here they are placed vertically and the bases connivent, so
that the effect of the whole is that of a pinnatifid leaf. The
fertile branches, however, have the leaves spirally arranged,
and in the sterile ones the three-sided apical cell is found. The
leaves, with few exceptions, c. g., Foiitinalis, have a w^ell-
marked midrib, and the lamina is single-layered. Leucobryum
(Fig. 121, A) has leaves made up of two or three layers of
cells, large hyaline ones, somewhat as in Sphagiuun, and small
green cells. The hyaline cells, as in Sphaguuiu, have round
holes in the walls, but no thickenings. The midrib may be
narrow, as in Fuiiaria, or it may occupy nearly the whole
breadth of the leaf, as in the Polytrichaceae, where, owing to
the almost complete suppression of the lamina, secondary ver-
tical plates of green cells are formed (Fig. 121, B).

The one-third divergence of the leaves found in Fontinalis^
is replaced in most other genera by a larger divergence.
(Goebel (8) ). Thus in Funaria hygromctrica it is f ; in Poly-
trichuni coiniminc -rs\ in P- formosum H-

As the archegonia are borne upon lateral branches, or upon
the main axis, the stegocarpous Bryine?e are frequently divided
into two main divisions, the Pleurocarp?e and the Acrocarpae,
which are in turn divided into a number of subdivisions or
families. How far the division into acrocarpous and pleuro-
carpous forms is a natural one may be doubted, as probably the
latter are secondary, and it is quite conceivable that different
families of pleurocarpous forms may have originated inde-
pendently from acrocarpous ones.

The simplest of the stegocarpous Mosses, while having the
operculum w^ell marked, have no peristome. Thus the genus
Gyinnostomiim has no peristome at all, and in an allied genus,
Hymenostomum, it is represented by a thin membrane covering
the top of the columella. In nearly related genera, however,
e. g., Weista, a genuine peristome is present.

The Tetraphidere, represented by the genus Tefrophis
(Georgia) (Fig. 118), are interesting as showing the possible
origin of the peristome, as well as some other interesting points

^This seems to be strictly the case only in the smaller branches; in the
larges axes the leaves are not exactly in three rows.

VI.

THE BRYALES

219

of structure. Tetraphis pcllncida is a small Moss, which at
the apex of its vegetative branches bears peculiar receptacles
containing multicellular gemmae of a very characteristic form.
The leaves that form the receptacle are smaller than the stem
leaves, and closely set so as to form a sort of cup in v^hich the
gemmae are produced in large numbers. These arise as slender
multicellular hairs, the end cell of which enlarges and forms a
disc, at first one-layered, but later, by the walls parallel to the
broad surfaces, becoming thicker in the middle, and lenticular

Fig. 118. — Tetraphis pellucida. A, Plant with gemmae, X6; B, upper part of the
same, X50; C, young gemma, X600; D, a fully-developed gemma, X300.

in form. The arrangement of the cells in the young gemmae
looks as if the growth of the bud was due to a two-sided apical
cell (Fig. 118, C), but this point was not positively determined.
These gemmae give rise to a protonema of a peculiar form, from
which in the usual way the leafy stems develop. The proto-
nemal filaments grow into flat thalloid expansions that recall
those of Sphagnum and Andre cbq.

220

MOSSES AND FERNS

CHAP.

The sporogonium of TctrapJiis has a peristome of peculiar
structure, and not strictly comparal)le to that of any of the
other Mosses. After the operculum falls off the tissue lying
beneath splits into four pointed teeth, which, however, are not,
as in Funaria, composed simply of the cell walls, but are masses
of tissue.

All the other higher Bryales, with the exception of the
Polytrichacese, have the peristome of essentially the same struc-
ture as that described for Funaria. Sometimes the teeth do not
separate but remain as a continuous membrane, c. g., the inner

AAAVMk
'f '■SI.*'

Fig. 119. — A, BarbuTa fallax, upper part of the capsule, showing the slender twisted
peristome teeth X about 20. B, Fontiualis antipyretica, showing double
peristome (after Schimper). C, Polytrichum commune, peristome and epiphragma
X8. D, P. commune, ripe capsule; i, with, 2, without the calyptra X3.

peristome of Biixbaumia, or a perforated membrane, as in Fon-
tiualis (Fig. 119, B).

The base of the capsule, or apophysis, which Haberlandt
(4) has shown to be the principal assimilative part of the sporo-
gonium, and which alone is provided with stomata, sometimes
becomes very large, and in the genus Splachuum (Vaizy (i))
especially forms a largely-developed expanded body, which
must be looked upon as a specially-developed assimilating ap-
paratus.

VI.

THE BRYALES

221

Undoubtedly the Polytrichaceae represent the highest stage
of development among the Musci. This is true both in regard
to the gametophore and the sporogonium. The former reaches
in some species, e. g., P. commune, a length of 20 centimetres
and sometimes more. The stem is usually angular and the
closely-set leaves thick and rigid. The numerous rhizoids are
often closely twisted together and form cable-like strands. The
structure of the leaves is very characteristic, and differs very
much from that of the simpler type found in Fiinaria.

Fig. 120. — Dau'sonia superba. A, upper part of female plant bearing a sporogonium,
Xi; B, a leaf, slightly enlarged; C, section of leaf, X about 70; D, part of the
same more highly magnified; E, two views of the capsule, Xi/^.

In the Polytrichacese (Fig. J2i) the midrib of the leaf is
very broad and only at the extreme margin of the leaf is the
lamina developed at all. A cross-section of the leaf shows that
the midrib is greatly thickened in the centre, and gradually
merges into the rudimentary lamina. In Dazvsonia (Fig. 120),
the leaf is almost flat, in Polytrichiim (Fig. 121), usually
more or less incurved at the margin.

The outer, or dorsal, surface of the leaf is covered with a
well marked epidermis, whose outer cell-walls are strongly

222 MOSSES AND FERNS chap.

thickened, and have a conspicuous cuticle. Within this epi-
dermis are closely set, small sclerenchymatous elongated cells,
among which are found more or less definite rows of large,
thin-walled elements, strongly suggesting the tracheary tissue
of the vascular plants, and without much question, true water-
conducting structures. From the inner ventral surface there
arise numerous parallel, thin, vertical laminae (cl.) composed
of green cells. These extend nearly the whole length of the
leaves and in section appear as rows of short cells, the outer-
most ones being somewhat enlarged.

The axis of the shoot in the Polytrichace?e shows a decidedly
complex structure and many reach a relatively large size.
Thus in Dazvsonia siipcrba (Figs. 120, 122) it is about 1.5 mm.
in diameter, and forms an erect, densely leafy shoot 40 to 50
centimetres in height. The cross-section of the shoot in the
latter species (Fig. 122) is triangular in outline. \\'ithin the
firm epidermis there are several layers of somewhat similar,
but more compact cells, which like the epidermal cells are thick-
walled, and dark coloured. This compact hypodermal tissue
passes somewhat gradually into a colourless, parenchymatous
ground-tissue, which makes up the bulk of the shoot-axis.
There is a very conspicuous central cylinder composed of two
tissue-elements — small, dark-colored sclerenchyma or fibrous
tissue, especially compact toward the centre of the cylinder ; and
very much larger, thin-walled cells, appearing almost destitute
of protoplasmic contents, and closely resembling the vessels of
true vascular plants, and like them, no doubt, true water-con-
ducting organs. Traversing the ground tissue are slender
strands of elongated cells — leaf-traces, which are structurally
like the central cylinder of the shoot, but with the water-
conducting cells less conspicuous. Most of the cells in the
stem of Dozvsonia, except the large tracheary cells of the central
cylinder, contain starch, which it is stated by Goebel (8) is not
abundant in the tissues of PolyfricJium, where its place is taken
largely by oil. Starch has been noted in Polytrichum in the
outer cells of the stem and in the leaf-traces.

The leaf-traces, or continuation of the central tissue of the
midribs of the leaves, bend down into the stem, and finally
unite with the axial cylinder of the latter, in a manner
quite analogous to that found in the stems of many vascular
plants.

VI.

THE BRYALES

223

Bastit ((i), p. 295),
who has made a compar-
ative study of the subter-
ranean and aerial stems of
P. jiiniperimnn, divides
the outer tissue of the lat-
ter into epidermis, hypo-
derma, and cortex. In
the subterranean stems he
finds the construction
quite different from that
of the leafy branches.
The section of the former
is trian,^ular, and its epi-
dermis provided with
hairs which are absent
from the epidermis of the
aerial parts. Rudimen-
tary scales, arranged in
three rows, are present,
and corresponding to
these are strands of tissue
that represent the leaf-
traces of the aerial stems.
The central cylinder is
much larger relatively
than in the leafy branches,
and its cross-section is not
continuous, but is inter-
rupted by three "pericyclic
sectors," composed of
cells whose walls are but
little thickened. The
point of each sector is at
the periphery of the me-
dulla, or central cylinder,
and the broad end toward
the centre. As might be
expected, intermediate con-
ditions are found where
the rhizome begins to grow upward to form a leafy branch.

Fig. 121. — A, Transverse section of the leaf of
Leucobryum; B, similar section of the leaf of
Polytrichum commune; cl, chlorophyll-bear-
ing cells (after Goebel).

224

MOSSES AND FERNS

CHAP.

The male inflorescence of the Polytrichacese is especially
conspicuous, as the leaves immediately surrounding the anther-
idia are different both in form and colour from those of the
stem. They are broad and membranaceous, and more or less
distinctly reddish in colour. A well-known peculiarity of
these forms is the fact that the growth of the stem is not
stopped by the formation of antheridia, but after the latter have
all been formed the axis resumes its growth and assumes the
character of an ordinary leafy shoot. This, of course, indi-
cates that, unlike most of the Mosses, the apical cell does not
become transformed into an antheridium, and the researches of

Fig. 122. — Dazi-sonia superba. A, Transverse section of the stem, XSS; B, part of the
central cylinder, showing water-conducting elements, t, X200; C, outer tissues
of the stem, X200.

Hofmeister (2), Leitgeb (9), and Goebel (7) have shown
that this is the case. The antheridia form groups at the base
of each leaf of the inflorescence, and Leitgeb thinks it probable
that each group represents a branch, i. c, the inflorescence is a
compound structure, and not directly comparable to the simple
male inflorescence of Fnnaria. The sporogonium in Foly-
trichum has a large intercellular space between the inner spore-
sac and columella as well as the one outside the outer spore-sac.
In both cases the space is traversed by the conferva-like green
filaments found in the other stegocarpous Mosses. The apoph-
ysis is well developed, especially in Polytrichum, and the

VI;

THE BRYALES

225

calyptra very large and covered with a dense growth of hairs
(Fig. 119, D).

The structure of the peristome in the Polytrichacese is
entirely different from that of the other Mosses. It is com-
posed of bundles of thickened fibrous cells arranged in crescent
form, the ends of the crescent pointing up, and united with the
adjacent end of the bundle next it. The tops of the teeth thus
formed are connected by a layer of cells stretching across the
opening like the head of a drum. This membrane is known
technically as the ''Epiphragm" (Fig. 119, C).

The Buxbaumiace^

The last group of Mosses to be considered is the very
peculiar one of the Buxbaumiacese. In these Mosses the

Fig. 123. — A, Protonema of Buxbaumia indusiata, with the anthreidial shoot, X17S;
B, antheridium, seen in optical section; C, sporophyte of B. sp., X4. (A, B, after Goebel.)

gametophyte is extraordinarily reduced, although the sporo-
gonium is large and well developed. So simple is the sexual
plant, that Goebel (i6) has concluded that these ought to be
taken away from the rest of the Mosses, and removed to a dis-
tinct order. According to Goebel's account, the antheridia,
which are long stalked, are borne directly upon the protonema,
and subtended by a single colourless bract (Fig. 123). The
female branches are also verv rudimentarv, but less so than the
male. On the strength of the extreme simplicity of these,
Goebel thinks that Biixhaiimia is a primitive form allied to some
alga-like progenitor of the Mosses. There are, however, two
very strong objections to this. First the sporogonium, wdiich
15

226 MOSSES AND FERNS chap.

is extremely large, and complicated in structure, and essentially
like that of the other stegocarpous Mosses; secondly, Biix-
bauuiia has been shown by Haberlandt ((4)' P- 4^0) to be
distinctly suprophytic in its habits, and the extreme reduction
of the assimilative tissue of the gametophyte is quite readily
explicable from this cause.

Fossil Muscine^

The remains of Muscinece in a fossil condition are exceed-
ingly scanty ; so much so indeed as to practically throw no light
upon the question of their origin and affinities, as nearly all of
the forms discovered belong to the later formations, and are
either identical with living species or closely allied forms. No
doubt the great delicacy of the tissues of most of them, espe-
cially the HepaticcX, accounts in great measure for their absence
from the earlier geological formations.

The Affinities of the Musci

It is perfectly evident that the Mosses as a wdiole form a
very clearly defined class, and that their relationship with other
forms is at best a somewhat remote one. Sphagnum, however,
certainly shows significant peculiarities that point to a connec-
tion between this genus, at least, and the Hepaticae. It will be
remembered that the protonema of Sphagnum is a large flat
thallus, and not filamentous, as in most Bryales. It it note-
worthy, however, that from the margin of this flat thallus later
filamentous branches grow out which are apparently identical
in structure with the ordinary protonemal filaments of the
Bryales. In Andrccca similar flat thalloid protonemata occur,
but not so largely developed as in Sphagnum, and finally in
Tctraphis a similar condition of affairs is met with. As this
occurs only among the lower meml:)ers of the ]\Ioss series, the
question naturally arises, does this have any phylogenetic mean-
ing? While it is impossible to answer this question positively,
it at any rate seems probable that it has a significance, and
means that the protonema has been derived from a thalloid
form related to some thallose Liverwort, and that by the sup-
pression of the thalloid portion, as the leafy gametophore
became more and more prominent, the filamentous branches,

VI. THE BRYALES 227

which at first were mere appendages of the thallus, finally came
to be all that was left of it. The view of Goebel and others that
the filamentous form of the protonema is the primitive one, and
indicates an origin from alga-like forms, might be maintained
if the question were concerned simply with the protonema ; but
when the structure of the sexual organs, especially the arche-
gonium, is considered, and the development of the sporophyte,
the difficulty of homologising these with the corresponding
parts in any known Alga is apparent, while on the other hand
the resemblance between them and those of the Hepaticae is
obvious. It is quite probable that the development of the fila-
mentous protonema is a provision for the production of a
greater number of gametophoric branches.

As to which group of the Hepaticae comes the nearest to
the Mosses, the answer is not doubtful. The remarkable simi-
larity in the development and structure of the sporogonium
of Sphagnum and the Anthocerotes leaves no room for doubt
that as far as Sphagnum is concerned, the latter come nearest
among existing forms to the ancestors of Sphagnum. Of
course this does not assume a direct connection between
Sphagnum and any known form among the Anthocerotes.
There are too many essential differences between the two to
allow any such assumption : but that the two groups have come
from a common stock is not impossible, and the structure of the
capsule in Sphagnum points to some form which like Antho-
ceros had a highly-developed assimilative system. This is
indicated by the presence of stomata, which, although function-
less, probably were once perfect, and make it likely that with
the great increase in the development of the gametophyte the
sporophyte has lost to some extent its assimilative functions
which have been assumed by the gametophyte.

Andrecea, both in regard to the gametophyte and the sporo-
phyte, is in many ways intermediate between Sphagnum and the
other Mosses. The resemblance in the dehiscence of the
sporogonium to that of the Jungermanniacese is probably acci-
dental. It may perhaps be equally well compared to the split-
ting of the upper part of the capsule into four parts, in Tetra-
phis, although in the latter it is the inner tissue and not the
epidermis which is thus divided.

If this latter suggestion proves to be true, then there would
be a direct connection of Andrecea with the ste^ocarpous

228 MOSSES AND FERNS ciiap.

Bryales, and not through the cleistocarpous forms. These
latter would then all have to be considered as degraded forms
derived from a stegocarpous type, unless, with Leitgeb, we
consider them as a distinct line of development leading up to
the higher Bryales, entirely independent of the Sphagnacese,
and with Archidhim and Ephemcnmi as the simplest forms.
His comparison of these forms with Notothylas, however, can-
not be maintained with our present knowledge of that genus,
and more evidence is needed before his view can be accepted ;
but the possibility of some such explanation of the cleistocarp-
ous Bryales must be borne in mind in trying to assign them
their place in the system.

The objections to considering Buxbaiwita a primitive type
have been already given, and it is not necessary to repeat them.

CHAPTER VII

THE PTERIDOPHYTA-FILICINE^-OPHIOGLOSSACE^

In tracing the evolution of the Bryophytes from the lowest to
the highest types the gradual increase in the importance of the
second generation, the sporophyte, is very manifest. This may
or may not be accompanied by a corresponding development of
the gametophyte. In the line of development represented by
the higher Mosses, in a general way the two have been parallel,
and the most highly differentiated gametophyte bears the most
complicated sporophyte, as may be seen in PoIytricJimn, for
example; but in the Hepatic^e this is not the case, and among
the Anthocerotes much the most highly organised sporophyte,
that of Anthoceros, is produced by a very simple gametophyte:

In this evolution of the sporophyte, it approaches a condition
where it is self-supporting, but in no case does it become abso-
lutely so. A special assimilative tissue, it is true, is developed,
and in some of the true Mosses, such as Splachmim, this goes so
far that a special organ, the apophysis, is formed ; but, as w^e
have seen, the sporogonium is dependent for its supply of w^ater
and nitrogenous food upon the gametophyte, with which it
remains intimately associated, and upon which it lives as a
parasite.

The type of structure found in the gametophyte of the
Muscinese seems to be imperfectly fitted for a strictly terres-
trial life. The gametophyte of all Archegoniates is more or less
amphibious. Free water is essential for the act of fecundation,
and the gametophyte seems never to have solved satisfactorily
the problem of an adequate water supply, except by returning

to the aquatic condition.

229

230 MOSSES AND FERNS chap.

Many Bryophytes can exist only in damp, shady localities,
and those which have adapted themselves to a xerophytic habit,
have acquired the power of becoming completely dried up with-
out being killed, reviving promptly when supplied with water,
but remaining completely dormant during the period of
drought. These plants do not depend upon their rhizoids for
absorbing water, but, like Algae, can absorb water at all points
of their surface. Where the plant depends largely upon the
rhizoids for water absorption, as in the Marchantiacese, the
plant is a flat, prostrate thallus, which offers a large surface for
the development of the rhizoids. In the upright stems of the
larger Mosses, the rhizoids are multicellular, and sometimes
twisted into root-like strands, which are of relatively large size,
and are undoubtedly efficient organs for water-absorption.
Still it is evident that even such strands of multicellular rhizoids
would not suffice for providing the water necessary to make
good the loss by transpiration in a large terrestrial plant.
It is this failure to develop an adequate root system which prob-
ably explains the fact that no Bryophyte has attained the dignity
of a successful upright terrestrial plant.

Among the Pteridophytes the gametophyte is equally in-
capable of a strictly terrestrial existence; but in these plants,
the sporophyte, developing still further along lines indicated in
many Bryophytes, has finally attained to the condition of an
independent plant. It may be conjectured that from part of
the foot, the absorbent organ of the embryo in the bryophytic
sporophyte, there was developed a root, with a permanent grow-
ing point, and capable of indefinite growth in length. This,
penetrating through the tissues of the gametophyte, put the
sporophyte into direct communication with the water in the
earth, and thus completely emancipated it from its former status
of dependence upon the gametophyte.

The true root differs essentially from the rhizoids in being
a massive organ capable of indefinite growth and division,
which can thus keep pace in its development with the increasing
size and complexity of the sporophyte. The latter from this
time assumes more and more the principal vtAe in the life-
history of the organism, while the gametophyte becomes corre-
spondingly reduced. With the development of an independent
sporophyte, there appeared a plant adapted from the first
to a terrestrial existence and not a modification of an originally

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACE^E 231

aquatic organism like the gametophyte of all Muscineae. In the
few cases where true roots are absent their plice is taken by
other structures that perform their functions. The assimilative
activity is restricted to special organs, the leaves, except in a few
cases where these become much reduced, as in Psilotum or Eqiii-
sctum. A main axis is present upon which the leaves are borne
as appendages, and this continues to form new leaves and
roots as long as the sporophyte lives.

The differentiation of these special organs begins while the
sporophyte is still very young. The earliest divisions in the
embryo correspond closely to those in the embryo of a Bryo-
phyte, but instead of forming simply a capsule, as in all the
Bryophytes, there is established more than one growing point,
each one forming a distinct organ. In the typical Ferns there
are four of these primary growing points, giving rise respect-
ively to the stem, leaf, root and foot. The latter is a tem-
porary structure, by which the young sporophyte absorbs food
from the gametophyte, but as soon as it becomes independent
the foot gradually withers away, and soon all trace of it is lost.

The originally homogeneous tissues of the embryo become
differentiated into the extremely complicated and varied tissues
characterising the mature sporophyte. The most characteris-
tic of these is the vascular system of tissues. This is hinted at
in the central strand of tissue in the seta of many Mosses, and
the columella of the Anthocerotes ; but in no Bryophyte does
it reach the perfect development found in the Ferns and their
relations, which are often called on this account the Vascular
Cryptogams.

The gradual reduction in the vegetative parts of the game-
tophyte, from the large long-lived prothallium of the Marat-
tiace?e to the excessively reduced one found in the heterosporous
Pteridophytes, has already been referred to in the introductory
chapter.

The structure of the sexual organs of the Pteridophytes
appears at first sight radically different from that of the
Bryophytes, but a careful comparison of the lower forms of the
former with some of the Hepaticse, and especially with the
Anthocerotes, shows that the difference is not so great as it at
first sight appears. A further discussion of this point must be
left, however, until we have considered more in detail the struc-
ture of these parts in the different groups of the Pteridophytes,

2Z2 MOSSES AND FERNS chap.

where they are remarkably uniform. In all of them the arche-
gonium has usually a neck composed of but four rows of per-
ipheral cells, instead of live or six, as in the Bryophytes, and the
antheridium, except in the leptosporangiate Ferns, is more or
less completely sunk in the tissue of the prothallium. The
spermatozoids are either biciliate, as in Mosses, or multiciliate,
a condition which, so far as is known, does not exist among the
Bryophytes.

The formation of spores is very much more sulxDrdinated
to the vegetative life of the sporophyte than is the case among
the most highly organised of the Bryophytes. Indeed it may be
many years before any signs of spore formation can be seen.
The spores are always born in special organs, sporangia, which
are for the most part outgrowths of the leaves, but may in a
few cases develop from the stem. In the simplest cases the
spores arise from a group of hy])odermal cells, generally trace-
able to a single primary cell. The cell outside of these divides
to form a several-layered wall, but the limits of the sporangium
are not definite, and it may scarcely project at all above the
general surface of the leaf. From this ''eusporangiate" condi-
tion found in Ophioglossimi, there is a complete series of forms
leading to the so-called leptosporangiate type, where the whole
sporangium is directly traceable to a single epidermal cell, and
where a very regular series of divisions takes place before the
archesporium is finally formed.

With very few exceptions all of the existing Pteridophytes
fall naturally into three series or classes of very unequal size.
The first of these, the Ferns or Filicine?e, is the predominant
one at present, and includes at least nine-tenths of all living
Pteridophytes. The Equisetinese are the most poorly repre-
sented of the modern groups, and include but a single genus
with about twenty-five species. The third class, the Lyco-
podine?e, is much richer both in genera and species than the
Equisetineae, but much inferior in both to the Filicine?e. The
disproportion between these groui)s was much less marked in
the earlier periods in the world's history, as is attested by the
very numerous and perfect remains of Pteridophytes occurring
especially in the coal-measures. At that time both the
Equisetineae and Lycopodine?e were much better developed
bntli in regard to size and numbers than they are at
present.

\ II PTERIDOPHYTA—FILICINEAI—OPHIOGLOSSACE^ 233

Class I. FilicinetE (Filicales)

The Filicineae or Filicales, as already stated, include by far
the greater number of existing Pteridophytes, and are much
more extended in range and abundant in numbers than either of
the other classes. A marked characteristic of all Ferns is the
large size of the leaves, which are also extremely complicated
in form in many of them. In a few of these the leaves are
simple, c. g., Ophioglossum, Viftaria, Pihilaria, but more com-
monly they are pinnately compound and sometimes of enormous
size. The stem varies a good deal in form and may be very
short and completely subterranean, as in species of Ophioglos-
sum and Botrychium, or it may be a creeping rhizome, or in
some of the large tropical Ferns it is upright, and grows to a
height of 8 to 10 metres, or even more.

While some forms of the Ferns are found adapted to almost
all situations, most of them are moisture-loving plants, and
reach their greatest development in the damp mountain forests
of the tropics. A few, e. g., Ceratopteris, Azolla, are genuine
aquatics, and still others, e. g., species of Gymnogramme, live
where they become absolutely dried up for several months each
year. These latter will quickly revive, however, as soon as
placed in water, and begin to grow at once. In the tropical
and semi-tropical regions many Ferns are epiphytes, and form
a most striking feature of the forest vegetation. With few ex-
ceptions the sporophyte is long-lived, but a few species are
annual, e. g., Ceratoptcris, and depend mainly upon the spores
for carrying the plant through from one season to another.
The sporophyte may give rise to others by simply branching in
the ordinary way, or special buds may be developed either from
the stem or upon the leaves (Cystopteris hulhifcra).

Besides the normal production of the gametophyte from
the spore, it may arise in va^rious ways directly from the
sporophyte (apospory) ; and conversely the latter may develop
as a bud from the gametophyte without the intervention of the
sexual organs (apogamy).

The Filicineae include both eusporangiate and leptospo-
rangiate forms, — indeed the latter occur only here. The former
comprise the homosporous orders, Ophioglossales and Maratti-
ales, and possibly the heterosporous order Isoetales, whose sys-
tematic position, however, it must be said is still doubtfuL The

234 MOSSES AND FERNS cum\

Leptosporangiatae include the single great homosporous order
Filices, and the two heterosporous families, closely related to
it, the Salviniacese and the Marsiliacese. These are usually
classed together as a distinct order, the Hydropterides or
Rhizocarpeae.

The Filicine.e Eusporangiat.e

The two orders, Ophioglossales and Marattiales, show
many evidences of being very ancient forms, and in several
respects seem to approach more nearly to the Hepatic?e than any
other Pteridophytes. While they are different from each other
in many respects, still there is sufficient evidence to indicate
that they belong to a common stock to warrant placing them
near each other in the system.

The Ophioglossales

The three genera belonging to this order may all be united
in a single family, Ophioglossacea^.

TJic Gamctophyte

Our knowledge of the gametophyte of the Ophioglossacese
has been very much augmented during the past ten years. Jef-
frey ( I ) has described very fully the gametophyte of Botry-
cJiiuin Virginianuin, and Lang (4) and Bruchmann (5) have
made out the most important facts in that of Ophioglossum and
Hchninthostachys. Our earlier knowledge was based entirely
upon the fragmentary observations of Hofmeister ( i ) upon
Botrychiiiin lunaria, and those of Mettenius (2) upon Ophio-
glossum pcdunculosinn.

The writer has succeeded in securing the earliest phases of
germination in two species, viz., Ophioglossum (Ophio-
derma) pendulum and Botrychium Virginiamim, as well as the
older prothallia of the latter. The germination in both cases
is extremely slow, especially in the former, where a year and a
half after the spores were sow^n the largest prothallia had but
three cells. Probably under natural conditions the growth is
more rapid. The spores of both forms show much the same
structure. The tetrahedral spores contain granular matter,

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACE^ 235

with numerous oil-drops, and a central large and distinct
nucleus. The exospore is colourless, and upon the outside
presents a pitted appearance in Ophioglossum, and irregular
small tubercles in Botrychium. The perinium or epispore is not
clearly distinguishable from the exospore. In both cases
chlorophyll is absent in the ripe spore. The first sign of ger-
mination is the absorption of water and splitting of the exospore
along the three radiating lines on the ventral surface of the
spore. The spore enlarges considerably before any divisions
occur, but remains globular in form, and no
chlorophyll can be detected. In this con- -g
dition, which was observed within two
w^eeks after the spores were sown in Ophio-
glossum, it may remain for several months
unchanged. The first division wall is
usually at right angles to the axis of the
spore, and divides it into two nearly equal
cells, of which the lower has more of the
granular contents than the upper one. The
endospore is noticeably thickened where it
protrudes through the ruptured exospore.
The next w^all, in all cases observed, is at
right angles to the first, and always in the
lower cell, which it divides into equal parts
(Figs. 124, 125). In Botrychhnn at this
stage a few large chloroplasts were seen in
both upper and lower cells, but Ophioglos-
sum showed no positive evidence of
chlorophyll, although it seemed sometimes
as if a faint trace of chlorophyll could be
detected. As growth proceeds, the oil
partially disappears, and the cells become
much more transparent than at first.

Lang (4) found the prothallia of Ophioglossum pendulum
buried in the humus collected about masses of epiphytic ferns
among which the sporophytes of the Ophioglossum were grow-
ing. The youngest ones discovered were nearly circular in out-
line, the older specimens more or less branched (Fig. 125, C).
The branches are cylindrical and grow from a single initial cell
which has the form of a four-sided pyramid. The lower half
of the prothallium is infested by an endophytic fungus, while

Fig. 124. — Germinating
spore of Ophioglossum
(Ophiodertna) pendu-
lum. A, Surface view;
6, optical section,
X600.

22>6

MOSSES AND FERNS

CHAP.

from the upper side of the thalkis the reproductive organs are
developed. Numerous rhizoids grow from the superficial cells.
Mettenius (2) has described the gametophyte in O. pedun-
culosum, which agrees in the main with that of 0. pcjidulujii.
In this species, however, there is first- developed a ^'primary
tubercle" (Fig. 125, B), and the branches were observed in
some cases to grow above the ground, where they became flat-
tened and developed chlorophyll.

Fig. 125. — A, 1', Prothallia of Ophioglossum pedunculosum, X i J^ ; B, shows the
young sporophyte, with the cotyledon and first root, r; t, the primary tubercle.
C-F, O. pendulum. C, An old prothallium, X6; D, nearly ripe antheridium; E,
surface view of antheridium, showing the opercular cell; F, nearly ripe arche-
gonium; D-F, X about 275; (A, D, after Mettenius; C-F, after Lang).

The Sex-Organs

The antheridium arises from a superficial cell which divides
by a periclinal wall into an inner cell, from which by further
divisions the mass of sperm-cells is derived, and an outer one,

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACE^ 2^

from which the cover of the antheridium is formed. The outer
wall of the antheridium remains for the most part but one cell
thick, in this respect more resembling- Marattia than it does
BotrycJiium. The antheridium also opens by a single, nearly
triangular opercular cell (Fig. 125, E), as it does in Marattia.
The spermatozoids were not seen, but probably resemble those
of Botrychiiim or Marattia.

The first division of the young archegonium is the same as in

^ ..$

Fig. 126. — A, Longitudinal section of a large prothallium of Botrychium Virginianum,
X15; B, transverse section of a somewhat younger one, showing the antheridial
ridge, and the archegonia; C, prothallium of Helminthostachys Zeylanica, X?',
D, young antheridium of Helminthostachys, X22S. (C, D, after Lang.)

the antheridium. From the inner cell, after it divides into a
basal and a central cell, is formed the axial row of cells — the
egg cell and the canal cells. No division of the neck canal cell
was observed beyond the division of the nucleus, and the ventral
canal was not seen ; but the latter is doubtless formed before the
archegonium is mature.

The neck of the archegonium remains very short, scarcely

238 MOSSES AND FERNS chap.

projecting at all above the surface of the prothallium, and
closely resembling in form the archegonium of the Tvlarattiacese.
Each of the four rows of neck cells contains three or four cells.
The basal cell may undergo divisions, but its limits remain
clearly visible in the ripe archegonium.

According to Mettenius ((2) PL xxx, Figs. 18, 19), O.
pedunculosum differs from O. pendulum in having the outer
wall of the antheridium double, as it is in Botrychhim. The
neck of the archegonium is also somewhat longer than in
O. pcndidmn. Bruchmann's account of O. viilgatnm agrees
closely with that of Lang for O. pendulum.

Botrychhim

In July, 1903, the writer found at Grosse Isle, Michigan, a
number of old prothallia of Botrychhim Virghhanum, with the
young sporophytes still attached, but nevertheless showing the
older stages of the sexual organs. In 1896, Jeffrey (i) was
fortunate enough to secure abundant material of this species,
including young prothallia, and succeeded in tracing very com-
pletely the development of the reproductive organs and embryo.
Owing to the kindness of Professor Jeffrey, who sent preserved
material, as well as prepared slides, I have been able to confirm
the results of his investigations.

The prothallium (Figs. 126, 127) is a subterranean, tuber-
ous body, much like that of B. lunaria described by Hofmeister,
but is very much larger. The specimens collected by the wTiter
were buried several centimetres below the surface, in rather dry
woods ; Jeffrey's material was in part found in a sphagnum bog,
partly in dryer localities.

The youngest specimens found by Jeffrey were oval, slightly
flattened bodies, which bore only antheridia. These occupied
the middle line of the upper surface, which later develops a
median ridge upon w'hich the antheridia are borne, while arche-
gonia appear later on either side of the antheridial ridge. (Fig.
126, B). In B. lunaria, according to Hofmeister ((i), p.
308), the archegonia are mostly formed upon the ventral
surface.

A section of the prothallium shows that the superficial tis-
sues are composed of relatively transparent cells, while the inner
tissue, especially toward the ventral side of the thallus, has very
dense contents, there being an oily substance present, as well as

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACE^ 239

granular matter. In these cells is found an endophytic fungus,
which probably acts as a mycorhiza. Multicellular hairs are
found growing from the upper surface of the prothallium.

The growth of the prothallium is distinctly apical, and a
single definite apical cell seemed to be present, although it is
possible that there may be more than one initial.

The infection of the thallus by the mycorhizal fungus Is
chiefly through the short rhizoids upon the inferior surface of
the thallus. Jeffrey concludes that the affinities of the fungus
are \N\\h the genera Pythium or Completoria.

Fig. 127. — Botrychium Virginianum. A, B, Germinating spore, X6oo; C, pro-
thallium (pr), with young sporophyte attached, X2; D, longitudinal section of the
prothallium, showing the foot of the embryo (F), X4; E, first (?) leaf of a
young sporophyte, X2.

As the prothallium grows older — it may evidently live for
several years — it becomes irregular in outline. It may finally
reach a length of twenty millimetres, and occasionally shows in-
dications of a dichotomy of the apex.

Scr-Organs

The first antheridia form a small group upon the upper sur-
face of the prothallium while it is still very young. The later
ones form only upon the median ridge already referred to.

240

MOSSES AND FERNS

CHAP.

Still later the archegonia appear along the base of the anther-
idial ridge (Fig. 126, B).

The development of the antheridium (Fig. 128) is much
like that of Ophioglossnm, but the outer wall of the antheridium
has normally two layers of cells. The spermatozoids, accord-
ing to Jeffrey, probably correspond with those of the true Ferns.
In a few cases observed by myself (Fig. 128, C) the primary
division walls of the central part of the antheridium were not
broken down by the separation of the sperm cells, but formed a
number of chambers.

The complete spermatozoid has about one and a half coils,

Fig. 128. — Botrychium I'irgintanum. Development of the antheridium, X about 450;
in C, the primary division walls within the antheridium have persisted, forming
large chambers, from which the ripe sperm-cplls are ejected successively.

and closely resembles that of the true Ferns and Equisetum,
like them having numerous cilia. They swarm within the
antheridium, and according to Jeffrey's account, escape through
on opening formed by the destruction of two superimposed
cells of the outer wall. They do not all escape at once, but are
ejected in separate swarms. It is possible that the formation
of the separate chaml>ers, noted by the writer, may have some-
thing to do with this phenomenon.

The development of the archegonium (Fig. 129) is much
like that of Ophioglossnm, but the neck of the archegonium is
much longer and projects conspicuously above the surface of

VII PTERIDOPHYTA—FILICIME^—OPHIOGLOSSACE^ 241

the thallus. The basal cell also divides more extensively, but
the group of cells derived from it is easily recognisable in the
ripe archegonium.

The central cell divides transversely, the low^er cell forming
the Qgg, and the ventral canal cell, the upper one giving rise
to the single neck canal cell, w^hose nucleus later divides as in
Ophioglossnm.

The mature Qgg cell contains dense cytoplasm, but has a
vacuole within it. Jeffrey observed a spermatozoid in the act
of penetrating the tgg, which showed an extension toward the
entering spermatozoid. The details of fertilisation, however,

Fig. 129. — Botrychium Virginianum. Development of the archegonium, X about 450.

were not made out, but they probably correspond closely with
those observed in other Ferns. "^

Helmin th osfachys

The gametophyte of Helminthostachys (Lang (4)), the

third genus of the Ophioglossaceae, does not differ essentially

from the other genera, being also subterranean. It is nearly

cylindrical in form (Fig. 126, C). The lower part, which is

brown, and covered with rhizoids, is sterile, and contains an
16

242

MOSSES AND FERNS

CHAP.

endophytic fungus. The upper portion, Hghter in colour, bears
the reproductive organs. Some of the prothaUia bear only
antheridia; the others have archegonia as well. As usual, the
first antheridia appear before any archegonia are formed. Both
archegonia and antheridia resemble those of BotrycJihim more
than they do those of Ophioglossnm.

The Embryo

The fertilised tgg, or oospore, becomes invested with a cell-
membrane and enlarges to several times its original bulk before

Fig. iT,o.—Botrych{um Virginianum. A, two-celled embryo within the archegonium
venter, X about 300; B, two sections of an 8-celled embryo; C, large embryo
showing the primary organs, X about 2$.

the first division wall is formed. This primary (basal) wall is
in most cases transverse, but may be somewhat oblique. The
two cells are generally more or less unequal in size, the upper or
epibasal cell being larger than the lower (hypobasal) one.
Each primary cell is next divided by a median vertical wall, and
the young embryo shows thus a regular quadrant formation.
The next divisions occur in the epibasal quadrants and are also
approximately transverse; at this stage, to judge from Jeffrey's
figures 43, 44, the embryo presents a striking resemblance to a
corresponding stage in Anthoceros.

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACEM 243

The subsequent divisions apparently show great irregu-
larity, and the embryo does not exhibit the early development
of apical initial cells so marked in the typical Ferns.

The whole epibasal part of the embryo is devoted to the for-
mation of the foot, in this respect showing an analogy, at least
with Anfhoceros. From the epibasal region arise the shoot and
the root, both of which later develop a definite apical cell. The
initial cell of the root at once begins to form periclinal cells,
which cut off the segments of the root cap from its outer face,
and the apical cell thus becomes deeply sunk beneath the surface
of the root-apex, which projects but little beyond the other parts
of the very massive embryo-sporophyte. The primary leaf, or
cotyledon (Fig. 130 cot.), unlike that of the true Ferns, arises
secondarily from the shoot.

In one instance, Jeffrey found small tracheids present in a
prothallium, but the young sporophyte had been destroyed, and
there was no means of determining wdiether this formation of
tracheids was associated with apogamy, as in all other similar
cases that have been observed.

The tissues adjacent to the venter of the archegonium grow
rapidly, keeping pace with the developing embryo, which
becomes very large before it breaks through the overlying
tissues (calyptra), which protect it. At this time, the very
large foot is especially conspicuous. The root is already some-
what elongated and shows a very definite arrangement of its
tissues, which resembles that of the later roots. A tetrahedral
apical cell is covered by a root-cap composed of several layers
of cells, and the axis of the root is occupied by a strand of nar-
row cells, which later develop into the vascular cylinder or
''stele" of the root.

The cotyledon, at this time, is relatively inconspicuous, and
forms a short, incurved, conical protuberance, between which
and the root lies the very slightly conical apex of the shoot.
Both stem and leaf show a fairly distinct apical cell, but these
apparently cannot be traced back to the original embryo-octants,
as is the case in the more specialised Ferns. A very short
procambium cylinder can somewhat later be seen in the axis
of the stem, and from it extends a similar strand into the cotyle-
don. The central cylinder of the stem (Jeffrey (i), p. 21)
becomes fully developed below the point of origin of the
cotyledon. From the first it is a hollow cylinder with a well-

244 MOSSES AND FERNS chap.

marked pith. The vascular ring is broken by a gap above the
first leaf-trace (cotyledonary stele), and the pith is thus thrown
into communication with the outer ground tissue, or cortex.

The first tracheary tissue appears shortly after the root has
broken through the calyptra, at which time the root has the
length of 5-20 millimetres. The development of the tracheary
tissue in the root begins at two, or more commonly three,
points, i. c, the root is either "diarch" or *'triarch." The in-
nermost layer of the fundamental tissue forms the "endoder-
mis" or bundle-sheath. As is usually the case, the endodermal
cells are characterised by the peculiar thickening or foldings of
the radial walls, which appear as elongated dots in transverse
sections. A similar endodermis can be made out, surrounding
the stelar tube of the stem.

The primary tracheids, or ''protoxylem," have reticulately
sculptured walls, and, except in size, closely resemble the secon-
dary tracheary elements, or "metaxylem," which are formed
centripetally, and meet in the centre of the vascular cylinder.
Between the xylem masses are as many masses of phloem, or
bast, made up in part of sieve-tubes with which are mingled
elongated paranchyma cells. Surrounding the circle of xylem
and phloem masses is the pericycle, composed of one or two
layers of parenchyma.

After the young root has broken through the calyptra and
penetrated the ground, the cotyledon grows upward and finally
makes its appearance above the surface of the ground. It
becomes differentiated into a slender, nearly cylindrical stalk
(stipe) and a much-divided lamina (Fig. 127, E). The single
primary vascular bundle of the leaf-rudiment divides into two
within the stalk, and passes into the two lateral lobes of the
lamina. From one of them a strong branch is developed which
constitutes the midrib of the central segment of the lamina.
The vascular bundles of the stipe approach the collateral type,
rather than the concentric structure found in the later formed
leaves.

Sometimes two or three roots are developed before the
cotyledon unfolds, and the young sporophyte remains for a long
time — probably two or three years — attached to the gameto-
phyte, the superficial cells of the foot remaining active during
this period. These cells show the dense cytoplasm and con-
spicuous nuclei of active cells.

VII PTERIDOPHYTA—FILICINEJE—OPHIOGLOSSACE^ 245

According to Mettenius, the cotyledon in OpJiioglossuni
pediinculosum develops much earlier than is the case in
Botrychiujji. It appears above the ground while the primary
root is still but little developed. (Fig. 125, B.)

In Botrychium hinaria, according to Hofmeister, the first
three leaves are rudimentary and the first green leaf does not
appear above ground until the second year.

Mettenius' account of the development of the embryo in
O. pediinculosum is less complete. The earliest stage seen by
him was already multicellular, and the young embryo had the
form of an oval cell mass in which the primary divisions were
not recognisable. The upper part, i. e., that next the arche-
gonium. neck, grows up at once into the cotyledon, while the
opposite part gives rise to the first root. These grow respect-
ively upward and downward*, and break through the overlying
prothallial cells. Later, at a point between the tw^o, the stem
apex is developed. The first leaf becomes green, and develops
a lamina similar to that of the later-formed ones. Usually but
one embryo is developed from the prothallium, but occasionally
two are formed, especially where the prothallium forks.

The Adult Sporophyte

Ophioglossum (Ophioderma) pendiilwn, an epiphyte com-
mon in the Eastern tropics, may be taken as a type of the sim-
plest of the Ophioglossacese. Its short creeping stem grows
upon the trunks of trees, especially tree-ferns, from which the
long flaccid leaves hang down. The lamina of the leaf merges
insensibly into the stout petiole whose fleshy base forms a sheath
about the next younger leaf. Corresponding to each leaf is a
thick unbranched root, which penetrates into the crevices of
the bark and holds the plant secure. These roots are smooth,
and show no trace of rhizoids. The petiole is continued up into
the lamina as a very broad and thick midrib, which in the spo-
riferous leaves (sporophylls) is continued into the peculiar
elongated spike which bears the sporangia.

The petiole if cut across shows a number of vascular bundles
arranged in a single row, nearly concentric with the periphery
of the section. As these enter the lamina they anastomose and
form a network with elongated meshes (Fig. 133, C) and no
free ends. Sections of the spike cut parallel to its broad

Fig, 121.— Op hioglossiim pendulum. A, Leaf with sporangiophore, natrual size; B,
cross-section of the petiole, X6; C, section of the sporangiophore, parallel to its
broad surface, X6.

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACE^ 24.9

diameter show a somewhat similar arrangement of the vasculai
bundles, but here there are free branches extending between the
sporangia. The relations of the bundles of the fertile and sterile
parts of the leaf are best
followed in the smaller
species. Prantl ((7), p.
155) describes it as fol-
lows for O. Lusitaniciim,
and states that it is essen-
tially the same in other
species. 'The primary
bundle given off from the
stem branches just after it
enters the petiole. The
main bundle gives off two
smaller lateral branches
right and left. The latter
branch again near the base
of the sporangiophore,and
the upper branches from
each unite to form the sin-
gle bundle that enters the
latter."

The sporangia are
sunk in the tissue of the
sporophyll, and scarcely
project at all above the
surface, where the position
of each one is indicated
by a faint transverse fur-
row which marks the
place where it opens.
Seen in sections parallel to
the flat surface these ap-
pear perfectly round, but
in transverse section are-^
kidney-shaped (Fig-
140, C).

The apex of the stem forms a blunt cone, which, however, is
not visible from the outside. A longitudinal section through
the end of the stem shows that it is covered by a sheath com-

FiG. i22.—'Ophioelossum vulgatum, Xi«

248

MOSSES AND FERNS

CHAP.

posed of several layers of cells, and this encloses a cavity in
which are the growing point of the stem and the youngest leaf.
The leaves here form much more rapidly than in the species of
the temperate regions, as the growth continues uninterruptedly
throughout the year. The real apex of the stem forms an in-
clined nearly plane surface, slightly raised in the centre, where
the single apical cell is placed (Fig.T34,A,B). This cell is by no
means conspicuous, and not always readily found, but probably

is always present. It has
the form of an inverted
three-sided pyramid, but the
lateral faces are more or less
strongly convex, and the
apex may be truncate. From
the few cases observed it is
not possible to say whether
in addition to the three sets
of lateral segments basal seg-
ments are also formed, but it
is by no means impossible
that such is the case. Ac-
cording to investigations of
Rostowzew ( ( I ) , p. 45 1 ) »
the apical cell of the stem
of OpJiioglossimi viilgatum
shows considerable variation,
and may be either a three or
four-sided prism, i. c, it ap-
parently also may have the
base truncate. Holle's (i)

Fig. 133. — Ophioglossum pendulum. A, Me-
dian longitudinal section of stem apex, X4;
X, the growing point; B, young sporophyll, description agrCCS Avith this
X2; sp, the sporangiophore; C, an older ^ *-

leaf, showing the venation, X2.

except that he states that he
always found the cell pointed
below, not truncate. The segments cut off from the lateral
faces are large, and the divisions irregular. They are appar-
ently formed in very slow succession, and the irregularity of the
succeeding divisions in the segments themselves soon makes it
impossible to trace their limits. Each segment apparently gives
rise to a leaf, but this is impossible to determine with certainty.
The first wall in the young segment proba1)ly divides it into an
inner and outer cell, but the next divisions could not be deter-

VII PTERIDOPHYTA—FILICINE^—OPIIIOGLOSSACEJE 249

mined positively. Probably, as in Botrychimn, the outer cell is
next divided by a vertical w^all, perpendicular to the broad
faces of the segment, into two cells, in which divisions then
take place in both transverse and longitudinal direction without
strict regularity.

The stem in O. pendulum is mostly made up of thin-walled
parenchyma, and the vascular bundles are much less developed
than is the case in the underground stem of O. zntlgafum or
Botrychiiim. The bundles are of the collateral form, i. c, the
inner side is occupied by the xylem, the outer by the phloem,

Fig. 134. — Ophioglosstim pendulum. A, Longitudinal section of stem apex, X6o; B,
the central part of the same section, Xi8o; D, longitudinal section of very young
sporangiophore, Xi8o; E, cross-section of young sporangiophore, X6o.

and there is no evident bundle-sheath developed. The bundles
form a very irregular wide-meshed cylinder, not differing essen-
tially from that in O. Z'ulgatiH

Van Tieghem (7) states that in Ophioglossiim vtilgatum
each vascular strand is completely invested with a distinct
endodermis and pericycle ; but Bower (16) found the endoder-
mis very poorly developed in the species studied by him,
especially O. Bergianiun, a small and simple species. The stem
of this form shows in transverse section two strands which may

250

MOSSES AND FERNS chap.

either be separate, or partly coherent, so as to form a single
crescent-shaped bundle, when seen in section. There may be,
however, even in this species, more than two strands present.
Poirault (2) found a definite endodermis in the lower part of
the stem, which disappears in the upper portion.

Van Tieghem asserts (see Bower (16), p. 67) that in the
young sporophyte of O. vulgatum, there is at first a solid axial
stele, with pericycle and endodermis, and that only above the
insertion of the first leaf does a pith appear.

In the bundles of the stem of O. pendulum, the xylem of the
collateral bundle is mainly composed of short irregular
tracheids, with close reticulate markings on the walls. The
phloem is composed of short, thin-walled cells with large nuclei.
No true sieve-tubes could be recognised.

The Leaf

The voung leaf is completely concealed by the sheath formed
at the base of the next older one. It is at first a conical pro-
tuberance arising close to the stem apex, around which its base
gradually grows and forms the sheath about it and the next
leaf rudiment. It is probable that here, as in O. vulgatum,^
the young leaf grows at first by a definite apical cell. After
the plant has reached a certain age, each leaf gives rise to a
sporangial spike, which becomes evident while the leaf is still
very small. The first indication of this is a conical outgrowth
upon the inner surface of the leaf, about halfway between the
apex and base. A longitudinal section of this shows it to be
made up of large cells, especially toward the top ; but although
there was sometimes an appearance that indicated the presence
of a single apical cell, this was by no means certain, and if there
is such an initial cell, its divisions must be very irregular.

Bower (16) found that in O. vulgatuin the young spo-
rangial spike grows from a single apical cell, which in less robust
specimens persists for a long time as a four-sided, initial cell,
but in the larger specimens seems to be replaced by four similar
initials.

The subsequent growth of the leaf is for a long time mainly
from the base, and the young sporangial spike is much nearer
the apex in the next stage (Fig. 133, B). No distinct petiole

^ Rostowzew (i), p. 45 1-

VII PTERIDOPHYTA—FILICINEJE—OPHIOGLOSSACEJE 251

has yet developed, but the centre of the young leaf, up to the
point of attachment of the spike, is traversed by the thick mid-
rib, above which the lamina is still very small. Indeed in this
stage it looks as if the spike were really terminal and the lamina
a lateral appendage. The young spike now forms a beak-
shaped body curving inward and upward, and sections of
slightly older stages than the one figured show the first indica-
tions of the developing sporangia. Later still the base of the
leaf becomes narrowed into the petiole, and the spike also
becomes divided into the upper sporiferous portion and the
short slender pedicel.

The anatomical structure of the leaf is extremely simple.
The epidermis is composed of
rather thick-walled cells, irreg-
ularly polygonal in outline,
with large stomata at intervals,
about which the cells are ar-
ranged concentrically, and fre-
quently with a good deal of
regularity. The stomata them-
selves (Fig. 135), seen from
above, have an angular outline,
but from below are perfectly
oval, and cross-sections show
that this appearance is due to a
partial overarching of the
guard cells of the stoma by the

surrounding epidermal cells. ^^^ ,^,,JZoma from the leaf of ophio-
The upper walls of the guard giossum pendulum, X260.

cells are thickened unequally,

giving them the appearance of being folded longitudinally.
There is no distinct hypoderma formed, and the bulk of the leaf
is made up of a uniform mesophyll composed of nearly globular
cells with much chlorophyll, and separated by numerous inter-
cellular spaces. In the petiole the tissues are similar, but more
compact, and the walls of the ground tissue are all deeply pitted.
The vascular bundles are nearly circular in section and show
a compact mass of tracheary tissue (Fig. 136, t), surrounded
by nearly uniform cells with moderately thick colourless walls.
The limits of the bundle are not, as in the higher Ferns, marked
by a distinct bundle-sheath, but are indicated simply by the

252 MOSSES AND FERNS chap.

somewhat smaller size of the cells of the bundle itself — indeed
it is not always easy to say exactly where the ground tissue
begins. The xylem is composed of pointed tracheids \vhose
walls are marked with thick reticulate bands. This mass of
tracheary tissue is situated near the inner side of the bundle,
which like that of the stem is collateral. The rest of the
bundle is composed of sieve-tubes mingled irregularly with
smaller cambiform cells. Whether or not sieve-tubes occur
upon the inner side of the bundle could not be positively deter-
mined. The sieve-tubes have transverse walls, and in O. viil-

FiG. 136. — Vascular bundle of the petiole of O. pendulum, X260; t, t, the xylera

of the bundle.

gatiiui lateral sieve-plates have been observed. The spo-
rangiophore has much the same anatomical structure as the rest
of the leaf, but stomata are quite absent from its epidermis.
In this respect 0. pendulum differs from O. vulgatum and
allied species, where stomata are developed upon the spo-
rangiophore as well as upon the rest of the leaf.

The Root

The roots are formed singly near the bases of the leaves,
and are light yellowish brown in colour, and so far as could be

VII

PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACEJE 253

seen, entirely unbranched. Sections show that here, as in most
vascular plants, the growing point of the root is not at the apex,
but some distance below and protected by the root-cap. The
growth of the root in Ophioglosstuu can be traced to a single
apical cell (Fig. 137), which is of large size, and, like that of
the stem, approximately pyramidal in form. While the divi-
sions show greater regularity than in the stem, still they are
very much less so than in the leptosporangiate Ferns. Seg-
ments are cut off not only from the lateral faces of the apical
cell, but also from its outer face. These outer segments help
to form the root-cap, which, however, is not derived exclusively

YiG. 137. — Ophioglossum pendulum. A, Longitudinal; B, transverse sections of

the root apex, X21S.

from these, but in part also from the outer cells of the lateral
segments. Each of the latter is first divided by a nearly ver-
tical wall, perpendicular to its broad faces, into two ''sextant
cells," but beyond this no regularity could be discovered in the
order of division in the segments, and the tissue at the growing
point, especially in longitudinal section, presents a very con-
fused arrangement of the cells. A little lower down two
regions are discernible, a central cylinder fplerome), w^hose
limits are not very clearly defined, and the periblem or cortex,
A definite epidermis is not distinguishable.

The first permanent tissue in the plerome cylinder or stele,
which is elliptical in section, arises in the form of small tracheids

254

MOSSES AND FERNS

CHAP.

near the foci of the elhptical section. From here the formation
proceeds towards the centre, and in the full-grown root the
tracheary tissue forms a continuous band occupying the larger
axis of the section, the last-formed tracheids being the largest.
On either side of this tracheary plate is a poorly defined mass
of phloem, similar to that of the stem and leaf bundles. An en-
dodermis or bundle sheath can be made out, although it is much
less prominent than in most roots. The endodermis is derived
from the innermost cortical layer, and the radial cell-walls are
characterised by a thickening, or folding of the wall. In O. vul-

gatitiu the bundle of
the root is diarch to
begin with, but by the
suppression of one of
the phloem masses it
becomes monarch.

The Sporangium

The development
of the sporangium has
been studied by
Goebel ((17), p.
390), in O. vidgatmn,
and recently by Bower
(16) in this species
and in 0. pendulum.
The latter has been
carefully examined by
the writer, and the re-
^'°' ii^-"^-/"'/,"'"'"-. \^T\^' ^""'^'f °^ '^" '°°*' suits confirm that of

X05, Ihe phloem is shaded; en, endodermis.

the latter investigator,
except that it seems possible that the archesporium may be
traced to a single cell, as Goebel asserts is probably the case in
O. vulgatum.

According to Bower (16), in all species examined by him,
the sporangia arise from a continuous band of superficial tissue,
on each side of the spike. To this he gives the name, ''sporan-
giogenic band." The sporangia arise from the sporangiogenic
band, at more or less definite intervals, separated bv intervals
of sterile cells. In the sporangial areas, periclinal walls sep-

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACEJE 255

arate an inner archesporium from the outer cells, destined to
form the wall of the sporangium. Between the young spo-
rangia the cells form sterile septa. The cell-groups which form
archesporia, and those which develop into sterile septa, are
sister-cell groups.

All of the sporogenous tissue cannot be traced back to the
primary archesporial cell, as later secondary sporogenous tissue
may be formed by further periclinal divisions in the outer cells
of the sporangium.

A transverse section of the very young sporangiophore is

Fig. 139. — A, Very young; B, older sporangia of O. pendulum,

X^6o.

transverse sections,

somewhat triangular, the broader side corresponding to the
outer surface of the sporangiophore. The cells are very irreg-
ular in form, and no differentiation of the tissues is to be
observed. Sections of somewhat older stages show in some
cases, at least, a large epidermal cell occupying nearly the
centre of the shorter sides of the triangular section. This cell
has a larger nucleus than its neighbours, and is decidedly
broader. The next stage was not observed, but a somewhat
more advanced one shows a small group of inner cells (shaded
in the figure), which appear to have arisen from the primary

256

MOSSES AND FERNS

CHAP.

cell by a transverse wall, although this point is exceedingly
difficult to determine on account of the great similarity of all
the cells (Fig. 139). This group of inner cells (or the single
one from which they perhaps come) constitutes the arche-
sporium, and by rapid division in all directions forms a large
mass of cells whose contents become denser than those of the

Fig. 140. — Ophioglossum pendulum. A, Section of a young sporangium, the arch-
esporial tissue is shaded, the inner cells with dark nuclei being the definitive
sporogenous cells, X200; B, transverse section of an older sporangium; sp,
sporangeous cells; t, tapetum, X about 35; C, a portion of B more highly magni-
fied; D, section of nearly mature sporangial spike, X8.

surrounding ones, between wdiich and these, however, the limits
are not very plain. Later, when the number of cells is com-
plete, the difference between them and the sterile tissue of the
sporangiophore is much more evident.

The cells lying outside of the archesporium divide rapidly
both by longitudinal and transverse walls, and form the thick
outer wall of the sporangium. In longitudinal sections, two

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACEJE 25?

rows of cells may be seen extending from the mass of arche-
sporial cells to the periphery. In these rows the vertical walls
have been more numerous than in the adjacent ones, so that
the number of cells in these rows is greater. It is between
these rows of cells that the cleft is formed by which the ripe
sporangium opens. The outer cells of the sporogenous tissue
do not develop into spores, but constitute the "tapetum" (Fig.
140, B, t), which serves to nourish the developing spores.

After the full number of cells is reached in the archesporium,
their walls become partially disorganized, and the cells round
off and separate, exactly as in the sporogonium of a Bryophyte,
and each cell is, potentially at least, a spore mother cell.
Bower (16) states that only a part of the cells produce spores,
and that the rest remain sterile and serve with the disorganised
tapetal cells to nourish the growing spores. The final division
of the spore mother cells into four spores is identical with that
of the Bryophytes.

At maturity the sporangium opens by a cleft, whose position
is indicated as we have seen in the younger stages, and as the
cells shrink with the drying of the ripe sporangiophore the
spores are forced out through this cleft.

OpJiioglossum milgatum and the other terrestrial forms
show some points of difference when compared with O. pen-
dulum. These grow much more slowly, and longitudinal sec-
tions of the upper part of the subterranean stem show several
leaves in different stages of development. Each leaf rudiment,
as in O. pendulum, is covered by a conical sheath, formed at
the base of the next older leaf, and these sheaths are open at the
top, so that there is direct communication between the outside
air and the youngest of these sheaths which encloses, as in the
latter species, the youngest leaf rudiment and stem apex (Ros-
towzew (i), p. 451). In these terrestrial forms, also, the
sporangiophore is longer stalked, and the lamina of the leaf
more clearly separated from the petiole, which is not continued
into it. The lamina is relatively broader and the venation more
complex, in some species showing also free endings to the ulti-
mate branches. The sporangia, too, project more strongly
and are very evident (Fig. 132). Branching of the roots
occurs occasionally, and according to Rostowzew may be either
spurious or genuine. In the first place an adventive bud, which
ordinarilv would develop into a stem, develops a single root and

2S8 MOSSES AND FERNS

CHAP.

then ceases to grow. This root appears to be formed directly
from the main root, and as the latter continues to grow the effect
is that of a true dichotomy. The latter does occur, but not
frequently.

The formation of adventitious buds upon the roots is the
principal method of propagation of some species of Ophioglos-
sum, whose prothallia, as we have seen, are apparently very
seldom developed. Rostowzew states that these are not de-
veloped from the apical cell of the root, but arise from one of
the younger segments, and the apical cell of the bud is produced
from one of the outer cells of the young segment, but is covered
by the root-cap, through which the bud afterwards breaks.
The sheath covering the first leaf of the bud is formed from the
cortex of the root and the root-cap.

Differing most widely from the other species in general
appearance is the curious epiphytic 0. (Chciroglossa) paUna-
tion. In this species the leaf is dichotomously branched, and
instead of a single sporangiophore there are a number arranged
in two row^s along the sides of the upper part of the petiole and
the base of the lamina.

According to Bitter ( ( i ) p. 468) , O. pendulum also has the
sterile leaf segment dichotomously divided, but this was never
the case in the specimens collected by the writer in various parts
of the Hawaiian Islands. These invariably had an undivided,
strap-shaped leaf.

In O. Bcrgianum the plant is very small and the sporangia
are reduced in number to a dozen or less. The sterile segment
is inserted very far down. A most remarkable form has been
recently described from Sumatra (Bower (20) ). This species,
O. simplex, is described as having no sterile leaf-segment, or the
merest rudiment of one, the sporophyll being a flattened slender
body, with the sporangia closely resembling those of O. pen-
dulum, to which 0. simplex seems to be allied. O. simplex
may be considered to represent the most primitive type of the
genus yet discovered.

BOTRYCHIUM

The genus Botryehium includes several exceedingly variable
species, the simplest forms, like B. simplex (Fig. 141, A, B),
being very close to Opiiioglossum, while leading from these is a

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACEM 259

series ending in much more complicated types, of which B. Vir-
giniannm is a good example. In B. simplex the lamina of the
leaf is either entirely undivided, as in most species of Ophioglos-
sum, or once pinnatifid. From these there is a complete series
to the ample decompound leaf of B. Virginianiim. When the
other parts of the plant are studied we find that this greater com-
plexity extends to them as well. Thus the sporangiophore is
also decompound, and the sporangia entirely free, showing an
approach to those of such Ferns as Osmnnda; and the venation,
which in the simpler forms is dichotomous, approaches the
pinnate type in B. Virginiamun. The tissues, especially the
vascular bundles, are also more highly differentiated in the
larger species.

Under favourable conditions well-grown plants of B. Vir-
ginianiim reach a height of 50 cm. or more, and the sterile
lamina of the leaf, which is triangular in outline, may be 30 to
40 cm. in breadth, and from three to four times pinnate. The
texture of the leaf is membranaceous and not fleshy like that
of OpJiioglossnm and most species of Botrychium. The sporan-
giophore is twice or thrice pinnate. The plant sends up a single
leaf each year from the underground stem, which is upright and
several centimetres in length in old specimens. The roots are
thick and fleshy, and much smaller at the point of insertion. As
in Ophioglossnm each root corresponds probably to a leaf, but
the roots branch frequently, so that the root system is much
better developed than in Ophioglossnm. The secondary roots
of B. Virginianiim arise laterally, and in much the same way as
those of the higher Ferns. As in the terrestrial species of
Ophioglossnm, the development of the leaves is very slow.

In most species of Botrychium the relation of the leaf base
to the young bud and stem apex is the same as in Ophioglossnm,
except that the sheath is more obviously formed from the leaf
base ; but in B. Virginianiim the. sheath is open on one side, and
more resembles a pair of stipules. Fig. 142, A shows the stem
and terminal bud of a plant of this species with all but the base
of the leaf of the present year cut away, and B the same with the
bud cut open longitudinally. At this stage the parts of the
leaf for the next year are well advanced, and the formation of
the individual sporangia just begun. The leaf for the second
year already shows the sporangiophore clearly evident, and the
leaf which is to unfold in three years is evident, but the sporan-

Fig. 141.— a, B, Botrychium simplex, slightly enlarged; C, B. tertwtum, X 5^ : D, leaf
segment of B. lunaria; E, leaf segment of B. I'irginianum, natural size; F, portion
of sterile leaf segment of Hclmintliostachys Zeylanica; G, fragment of the sporan-
giophore of the same enlarged. A, B, C after Luerssen; D, F after Hooker.

VII PTERIDOPHYTA—FILICINEJE—OPHIOGLOSSACE^ 261

giophore not yet differentiated. At the base of the youngest
leaf is the stem apex. The whole bud is covered in this species
with numerous short hairs, which are also found in B. ternattwi
and some other species ; but in B. simplex and the other simpler
species it is perfectly smooth, as in Ophioglossiim. The young
leaves in B. Virginiamim are bent over, and the segments of the
leaf are bent inw^ard in a way that recalls the vernation of the
true Ferns. The sporangiophore grows out from the inner
surface of the lamina, and its branches are directed in the
opposite direction from those of the sterile part of the leaf.

Fig. 142. — Botrychium Virginiamim. A, Rhizome and terminal bud of a strong plant,
the roots and all but the base of the oldest leaf removed, X i ; B, longitudinal sec-
tion of the bud, X3; st, the stem apex; I. II. III., the leaves; C, transverse sec-
tion of the petiole, X4; D, transverse section of the rhizome, X about 16; P,
the pith; m, medullary rays; x, xylem; c, cambium; ph, phloem; sJi, endodermis.

The vascular bundles of the stem are much more prominent
than in Ophioglossiim, and form a hollow cylinder, with small
gaps only, corresponding to the leaves. This cylinder shows
the tissues arranged in a manner that more nearly reseml^les the
structure of the stem in Gymnosperms or normal Dicotyledons
than anything else. Surrounding the central pith (Fig. 142, P)
is a ring of woody tissue {x) w^ith radiating medullary rays
(w), and outside of this a ring of phloem, separated from the

262 MOSSES AND FERNS chap.

xylem by a zone of cambium (c), so that here alone among the
Ferns the bundles are capable of secondary thickening. The
whole cylinder is enclosed by a bundle-sheath (endodermis)
consisting of a single layer of cells.

The cortical part of the stem is mainly composed of starch-
bearing parenchyma, but the outermost layers show a formation
of cork, which also is developed in the cortical portions of the
roots.

The free surface of the stem apex is very narrow, and the
cells about it correspondingly compressed. The apical cell
(Fig. 143, A, B), seen in longitudinal section, is very deep and
narrow, but as comparison of cross and longitudinal sections
shows, has the characteristic pyramidal form, and here there is
no doubt that only lateral segments are cut off from it. Holle's
((i) PL iv., Fig. 32) figure of Botrychium rntccfolhun closely
resembles B. Virginiamim, and probably the other species will
show the same form of apical cell. The divisions are decidedly
more regular in the segments of B. Virginiamim than in Ophio-
glossum, and can be more easily followed, although here, too, as
the division evidently proceeds very slowly, it is difficult to trace
the limits of the segments beyond the first complete set, which
in transverse section are sufficiently clear. The first division
divides the segment into an inner and an outer cell, the former
probably being directly the initial for the central cylinder. The
outer cell by later divisions forms the cortex, and the epidermis
which covers the very small exposed surface of the stem apex.
As in Ophioglossum, it is impossible to determine exactly the
method of origin of the young leaves, one of which probably
corresponds to each segment of the apical cell, but as soon as the
leaf can be recognised as such it is already a multicellular organ.
It grows at first by an apical cell which seems to correspond
closely in its growth with that of the stem. From almost the
very first (Fig. 143) the growth of the leaf is stronger on the
outer side, and in consequence it bends inward over the stem
apex.

The arrangement of the tissues of the fully-developed stem
shows, as we have seen, a striking similarity to that in the
stems of many Spermatophytes. The xylem of the strictly
collateral bundle is made up principally of large prismatic
tracheids (Fig. 144), whose walls are marked with bordered
pits not unlike those so characteristic of the Coniferse, but some-

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACEM 263

what intermediate between these and the elongated ones found
in most Ferns. The walls between the pits are very much
thickened, and the bottoms of corresponding pits in the walls of
adjacent tracheids are separated by a very delicate membrane.
At intervals medullary rays, one cell thick, extend from the pith
to the outer limit of the xylem. The cells are elongated radially,
and have uniformly thickened walls and granular contents.

The phloem consists of large sieve-tubes and similar but
smaller parenchymatous cells. No bast fibres or sclerenchy-
matous cells are present. The whole cylinder is bounded by

Fig. 143. — Botrychium Virgtnianiim. A, Longitudinal section of the stem apex of a
young plant, X260; B, cross-section of a similar specimen; L, the youngest leaf.

a single layer of cells somewhat compressed radially, forming
the endodermis or bundle-sheath. Between the xylem and
phloem is a well-defined layer of cambium by whose growth the
thickness of the vascular cylinder is slowly but constantly added
to, and as a result there is a secondary growth of the stem
strictly comparable to that of the Dicotyledons.

The outer layer of the cortex (the epidermis is quite absent)
develops cork, but not from a definite cork cambium (Holle,
(i), p. 249). These cork cells arise by repeated tangential
divisions in cells near the periphery, and have in consequence
the same regular arrangement seen in similar cells of the higher
plants.

264

MOSSES AND FERNS

CHAP.

A cross-section of the petiole of the earhest leaves of the
young plant shows but a single nearly central vascular bundle,
but as the plant grows older the number becomes much larger,
and may reach ten (Luerssen (8), p. 58). In leaves of mod-
erate size there are usually about four, and these are arranged
symmetrically. The ground tissue is composed mainly of
large thin-walled parenchyma and a well-marked epidermis.
The fibrovascular bundles are arranged in two groups, right and
left, and where there are four of them the inner ones are the

QStDQx

Fig. 144. — A, Part of a cross-section of the stem bundle of B. Virginianum, X200, —
lettering as in Fig. 142; B, a portion of the tracheary tissue, showing the peculiarly
pitted walls, X400.

larger, and in cross-section crescent-shaped. The xylem occu-
pies the middle of the section, and is completely surrounded by
the phloem, i.e., the bundle is concentric, like that of the true
Ferns. In B. lunaria the bundle has the phloem only perfectly
developed on its outer side and approaches the collateral form.
B. tcrnatinn and B. lunaria, while having concentric bundles,
also have the phloem more strongly developed on the outer side.
The tracheary tissue is much like that of the stem, but the
tracheids are smaller and the walls thinner. The smaller tra-
cheids show reticulate markings.

VII

PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACE^ 265

The phloem is composed also of the same elements, large
sieve-tubes, arranged in a pretty definite zone next the xylem,
and smaller cells of similar appearance, but not showing the
multinucleate character or perforated transverse walls of the
latter. The sieve-tubes are large (Fig. 145), and in longi-
tudinal section are seen to consist of rows of wide cells with
either horizontal or oblique division w^alls. The transverse
walls separating two members of a sieve-tube are somewhat
swollen and show small perforations, which are not always

U^'

Ph..

-••X^

Fig. 145. — Part ot a vascular bundle from the petiole of B. Virginiamim, X245; xy,
xylem; ph, phloem; s, s, sieve-tubes; B, two sieve-tubes in longitudinal section,
X490; sp, sieve-plates; n, nuclei.

easily demonstrated. According to Janczewski (4) these pits
do not penetrate the membrane betW'Cen the cells, but Russow's
(5) assumption that there is direct communication betw^een the
cells is correct, although difficult to prove. Russow also states
that callus is present in the sieve-plates of Botrychhim, although
poorly developed. According to Janczewski the pores are not
confined to the transverse walls, but may also occur, but much
less frequently, in the longitudinal walls. The contents of the

266

MOSSES AND FERNS

CHAP.

sieve-tubes consist of a thin parietal layer of protoplasm in
which numerous nuclei are imbedded. Little glistening glob-
ules are also found, especially close to the openings of the pores
of the sieve-plates.

The lamina of the sterile segment of the leaf is composed
of a spongy green mesophyll, more compact on the upper sur-
face. The epidermal cells show the wavy outlines characteristic
of the broad leaves of other Ferns, and develop stomata only
upon the lower side of the leaf.

Fig. 146. — Botrychium Virginiannm. A, Longitudinal; B, transverse sections of the

root apex, X-200; pi, plerome.

The Root

The roots arise singly at the bases of the leaves, and in
older plants branch monopodially. Like those of Opliioglossum
they have no root-hairs, but the smooth surface of the younger
roots becomes often strongly wrinkled in the older ones. Sec-
tions either transverse or longitudinal, through the root tip,
when compared with those of Ophioglossiun, show a very much
greater regularity in the disposition of the cells. This is less
marked in B. tcrnatnm, and probably an examination of such
forms as B. simplex will show an approximation to the condi-
tion found in Ophioglossnin, although Holle's figure of B. lunor-

VII PTERIDOPHYTA—FILICINE^—OPHIOGLOSSACE^ 267

ria shows even greater regularity in the arrangement of the
apical meristem than is found in B. Virginianmn, A careful
examination of this point is much to be desired.

The first wall in the young lateral segment is the sextant
wall, as in the higher Ferns, and divides the segment into two
cells of unequal depth. The next wall divides the larger of
these cells into an inner and an outer one, the former becoming
the initial of the central plerome cylinder, the outer one, to-
gether with the whole of the smaller semi-segment, giving rise
to the cortex, in which the divisions are very similar to, but

Fig. 147. — Tetrarch vascular bundle of the root of B. Virginianum, X85; en, endo-

dermis; ph, phloem; x, xylem.

somewhat less regular than in Equisetum and the leptospo-
rangiate Ferns. As usual in roots of this type, segments are
also cut off from the outer face of the apical cell, but I have never
seen, either in B. Virginimtum or B. tcrnatiim, any indica-
tion that the growth of the root-cap w^as due exclusively to the
development of these segments, as Holle states both for B.
Innaria and Ophioglossum znilgaHim. In both species of Bofry-
chium examined by me the growth of the root-cap was evidently
due in part to the division of cells in the outer part of the lateral
segments, so that in exactly median sections there was not the

268 MOSSES AND FERNS chap.

dear separation of the root-cap from the body of the root that
is so distinct in Equisctum, for example.

The central cylinder of the root is bounded by an endoder-
mis whose limits, however, are not so clearly defined as in the
more specialised Ferns. The number of xylem and phloem
masses varies, even in the same species. In B. Virginiamim
the larger roots show three or four xylem masses (Fig. 147).
B. tcrnatiini^ has usually a triarch bundle, while B. lunaria is
commonly diarch (Holle (i), p. 245). The elements both of
the xylem and phloem are much like those in the stem and do
not need any special description. The roots increase consider-
ably in diameter as they grow older, but this enlargement does
not take place at the base, where the root is noticeably con-
stricted. The enlargement is due entirely to the cortical tissue,
and is mainly simply an enlargement of the cells. The diameter
of the central cylinder remains the same after it is once formed.
In the outer part of the root, as in the stem, there is a develop-
ment of cork.

The Sporangium

In the simplest forms of B. simplex the sporangia, wdiich
are much larger than those of B. Virginianum, form two rows
very much as in Ophioglossum; but in all the more complicated
forms the sporangiophore branches in much the same \vay as
the sterile part of the leaf, and the ultimate segments become
the sporangia. In B. Virginianum the development of the
individual sporangia begins just al30Ut a year previous to their
ripening, and if the plants are taken up about the time the
spores are shed, the earliest stages may be found. The sporan-
giophore is at this time thrice pinnate in the larger specimens,
and an examination of its ultimate divisions will show the
youngest recognisable sporangia. These form slight elevations
growing smaller toward the end of the segment (Fig. 148),
and exact median sections show that at the apex of the broadly
conical prominence which is the first stage of the young sporan-
gium there is a large pyramidal cell with a truncate apex.
Holtzman (i) thinks the sporangium may be traceable to a
single cell, and that the divisions at first are like those in a
three-sided apical cell. I was unable to satisfy myself on this

^ B. tcrnatum = B. obliqiium (Underwood (5) p. 72).

VII PTERIDOPHYTA—FILICINEJE—OPHIOGLOSSACEJE 269

point, but the youngest stages found by me in which the
sporangial nature of the outgrowths was unmistakable, would
not forbid such an interpretation, although there was no doubt
that the basal part of the sporangium is derived in part from the
surrounding tissue.

From the central cell, by a periclinal wall, an inner cell,
the archesporium, is separated from an outer one. The outer
cell divides next by cross walls, and this is followed by similar
divisions in the inner cells (Fig. 148). The succeeding divi-

FiG. 148. — Botrychium Virginianum. Development of the sporangia. A, i, 2,
Very young sporangia; B, a somewhat older one, X480; C, older sporangium,
X240; all median longitudinal sections, the sporogenous cells are shaded.

sions in the outer cells are now mainly periclinal, and transform
the four cells lying immediately above the archesporium into
as many rows of tabular cells. Growth is active in the mean-
time in the basal part of the sporangium, which projects more
and more until it becomes almost spherical. To judge from
the account given by Goebel (3) and Bower ( 16) of B. hinaria,
this species corresponds closely in its early stages to B. Vir-
ginianum. The later divisions in the archesporium do not
apparently follow any definite rule, but divisions take place
in all directions until a very large number of cells is formed.

270

MOSSES AND FERNS chap.

The cells immediately adjoining the sporogenous tissue divide
into tabular cells, some of which contribute to the tapetum,
which is to some extent, at least, derived from the outer cells of
the sporogenous complex, as in OpJiioglossum. (See also
Goebel {22) p. 758). The sporangium shortly before the
isolation of the spore mother cells (Fig. 148 C) is a nearly glob-
ular body with a thick, very short stalk. The central part of the
upper portion is occupied by the sporogenous tissue surrounded
by a massive wall of several layers of cells. The central cells,
as usual, have larger nuclei, and more granular contents than the
outer ones. The stages 1)etween this and the ripe sporangium
were not seen, so that it cannot 1)e stated positively whether all
the cells of the definitive sporogenous tissue (which seems
probable) or only a part of them, as in OpJiioglossiiin, develop
spores. The wall of the ripe sporangium has 4-6 layers of cells,
and sometimes the place of dehiscence is indicated, as in Ophio-
glossiuji, by two rows of smaller cells (Fig. 148, C).

The stalk is traversed by a short vascular bundle, which is
first evident about the time that the number of sporogenous
cells is complete, and joins directly with the young vascular
bundle of the leaf segment (Fig. 148, C) . The ripe sporangium
opens by a transverse slit, as in Ophioglossum.

The presence of fungous filaments in the roots of the
Ophioglossace?e has been repeatedly observed, and has been the
subject of recent investigations by Atkinson (2), who is inclined
to regard them as of the same nature as the mycorhiza found
in connection with the roots of many Dicotyledons, especially
CupulifercT. Atkinson asserts that he finds them invariably
present in all the forms he has examined ; but Holle ( i ) states
that, while they are usually present in Ophioglossuiii, he has
found strong roots entirely free from them, and that in Botry-
chiiim nitccfolinm they were mainly confined to the diarch roots,
and that this is connected with a weakening of the growth of
the root through the growth of the fungus, by which the triarch
bundle of the normal fully-developed root is replaced by the
diarch form of the weaker one.

Helminthostachys

The third genus of the Ophioglossace?e, Hehninthostachys,
with the single species H. Zcylanica, is in some respects inter-

VII PTERIDOPHYTA—FILICINEAl—OPHIOGLOSSACEM 271

mediate between the other two, but differs from both in some
particulars. The sporophyte has a creeping tleshy subterranean
rhizome, with the insertion of the leaves corresponchng to Ophio-
glossum pendulum. According to Prantl (7), w^ho has made a
somewhat careful study of a plant, the roots do not show any
definite relation to the leaves, as Holle claims is the case in the
other genera. The plant sends up a single leaf, which may
reach a height of 30 to 40 cm. or more, and as in the Ophio-
glossujH viilgatum and B. Virginianum, the sporangiophore
arises from the base of the sterile division of the leaf. The
latter is ternately lobed, and the primary divisions are also
divided again. The venation is different from that of the other
Ophioglossaceae, and is extremely like that of Angiopteris or
Dancca. Each pinnule is traversed by a strong midrib, from
which lateral dichotomously branched veins run to the margin.
In regard to the structure of the sheath that encloses the young
leaf and stem apex, Helrninthostachys resembles Botrychmm.

The apex of the stem, as in the other genera, grows from a
single initial cell. The stem has a single axial stele, with the
form of a hollow cylinder, interrupted upon the upper side by
the leaf-gaps. In the youngest stems, the stele is solid. There
is an imperfect inner, and a distinct outer endodermis. The
xylem is mesarch — i. e., it begins to develop in the center of the
bundle — and its differentiation goes on very slowly. There is
no formation of secondary wood as in .the larger species of
Botrychmm. (Farmer (6)).

The sieve-tubes have sieve-plates on their lateral faces, and
similar sieve areas occur upon the walls of the adjacent phloem
cells. The metaxylem has tordered pits, apparently similar to
those of Botrychium Virginianitin.

The roots resemble those of Botrychium. There are from
three to seven xylem masses.

The sporangiophore is long-stalked and in general appear-
ance intermediate between that of the other genera, but a careful
examination shows that it is much more like that of Botrychmm.
It is pinnately branched, but in an irregular way, and the small
branchlets bear crowded oval sporangia, which open longi-
tudinally on the outer side, and not transversely as in the other
genera. The tips of the branches, instead of forming sporangia
as in Botrychium, develop into green leaf-like lobes, which upon
the shorter branchlets are often arranged in a rosette of three or

272

MOSSES AND FERNS chap.

four together, with the sporangia close below them (Fig. 141,
D). This at first sight looks as if the sporangia were produced
upon the lower side of these, like Equisetum, but a very slight
examination shows at once that this is only apparent, and the
sporangia are undoubtedly outgrowths of the branches as in
Botrychium. The green lobes are seen to be only the vegetative
tips of the branches, or perhaps better comparable to such sterile
leaf segments as are not uncommon in Osmunda Claytoniana.
(Bower (17), Goebel (22), p. 664.)

The sporangiophore in Helminthostachys originates as in
the other genera, and is bent over and protected by the sterile
leaf-segment, very much as in Botrychium. There is a certain
correspondence between the early stages of the sporangiophore
of Helminthostachys and that of Ophioglossiim, but in the
former there are later developed short lateral outgrowths, or
secondary sporangiophores, which bear clusters of sporangia
more like those of Botrychium, but the pinnate form of the
sporangiophore is much less evident.

The young sporangia project less than those of Botrychium,
but otherwise closely resemble them. The archesporium is
referable to a single mother-cell, but the tapetum is derived from
the surrounding tissue, and not from the primary archesporium,
as in Ophioglossum. Some of the sporogenous cells, as in
Ophioglossum., become broken down.

CHAPTER VIII

MARATTIALES

The Marattiace^

The Marattiacese, the sole existing family of the order, at the
present time includes five known genera, with about twenty-
five species of tropical and sub-tropical Ferns. Many fossil
types are known which evidently were related to the Marat-
tiacese, and they seem to comprise the majority of the Palaeo-
zoic Ferns.

Recently a good deal of attention has been paid to these
Ferns, and our knowledge of their life-history and structure is
fairly complete. Some of them are plants of gigantic size.
Thus the stem of Angioptcris cvecta is sometimes nearly a metre
in height and almost as thick, with leaves 5 to 6 metres in length,
and some species of Maraffia are almost as large. The other
genera, Kaiilfussia, Archangiopteris and Dancua, include only
species of small or medium size. While in the structure of the
tissues and the character of the sporangia these show some
resemblances to the Ophioglossacese, their general appearance is
more like that of the true Ferns, with which they also agree in
the circinate vernation of their leaves. The sporangia are borne
upon the lower surface of ordinary leaves, as in most lepto-
sporangiate Ferns, but the sporangia themselves are very differ-
ent, and are more or less completely united into groups or
synangia, which open either by longitudinal slits or, in Dancea,
by a terminal pore. The base of the leaf is provided with a
pair of fleshy stipules, which possibly correspond to the sheath
at the base of the petiole in Bofrychmm.
18 273

274

MOSSES AND FERNS chap.

The Gamctophyte

The germination of the spores and development of the
prothalhum were first investigated by Luerssen (5) and Jonk-
man (i) in Angioptcris and Marattia, and later by the latter
investigator for Kaiilfiissia (2). More recently Brebner (i)
has described the prothallium and embryo in Dancca.

The spores are of two kinds, bilateral and tetrahedral, but
the former are more common. They contain no chlorophyll,
but oil is present in drops of varying size, as well as other
granular bodies. The nucleus occupies the centre of the spore
and is connected with the wall by fine protoplasmic filaments.
The wall of the spore is colourless and shows three coats, of
which the outer one (perinium) is covered with fine tubercles.

Germination begins within a few days and is first indicated
by the development of chlorophyll. This does not, as Jonkman
asserts, first appear in amorphous masses, but very small,
faintly-tinted chromatophores are present between the large oil-
drops, and rapidly increase in size and depth of colour as ger-
mination proceeds, their number increasing by the ordinary
division. In the bilateral spores the exospore is burst open
above the thickened ventral ridge found in these spores, and the
growing endospore slowly protrudes through this. The spore
enlarges to several times its original diameter before the first
division occurs, and forms a globular cell in which the large
chloroplasts are arranged peripherally.

The first division takes place about a month after the spores
are sown, and is perpendicular to the longer axis of the cell,
dividing it either into two equal parts, or the lower may be
much smaller and develop into a rhizoid. In the former case
each cell next divides by walls at right angles to the first, and
the resulting cells are arranged like the quadrants of a circle, and
one of these cells becomes the two-sided apical cell from which
the young prothallium for a long time grows (Fig. 149), much
as in Ancura. This type of prothallium, according to Jonkman,
is commoner in Marattia than in Angioptcris^ where more com-
monly a cell mass is the first result of germination. This latter
is usually derived from the form where a rhizoid is developed
at first. In this case only the larger of the primary cells gives
rise to the prothallium. In the larger cell, divisions take place
in three directions and transform it into a nearly globular cell

VIII

MARATTIALES

275

mass, terminated by four quadrant cells, one of which usually
becomes the apical cell, much as in the flat prothallium. In
exceptional cases the first divisions are in one plane and a short
filament results.

As soon as the apical cell is established it grows in precisely
the same way as the similar cell in the thallus of a Liverwort,
and produces a thallus of much the same form and structure.
As the prothallium growls older, however, a cross-wall forms in

Fig. 149. — Angiopteris evecta. Germination of the spores, — A, B, X220; C, X175;
sp, spore membrane; x, apical cell (after Jonkman).

the apical cell, and this is followed by a longitudinal wall in the
outer one, forming two similar cells which, by further longi-
tudinal divisions, may produce a row of marginal initials, and
the subsequent growth of the prothallium is due to the divisions
and growth of this group of initial cells (Fig. 150, A).

At first the prothallium has a spatulate form, but before the
single apical cell is replaced by the group of marginal initials,
the outer cells of the segments grow more rapidly than the
inner ones, and the segments project beyond the apical cell,

2y(i

MOSSES AND FERNS

CHAP.

which comes to He in a depression between the two lobes formed
by the outer parts of the segments, and the prothalhum assumes
the heart-shape found in most homosporous Ferns. The sec-
ondary initial cells vary in number with the width of the inden-
tation in which they lie. Seen from the surface they are oblong
in shape, but in vertical section are nearly semicircular (I'ig.
150, B). Basal segments are cut off by a wall that extends
the whole depth of the prothallium, and the segment is then
divided by a horizontal wall into a dorsal and ventral cell of
nearly equal size. The divisions are more numerous in the

ventral than in the dorsal
cells of the segment, this
difference first being mani-
fest some distance back of
the apex. Owing to this, a
strongly projecting, nearly
hemispherical cushion - like
mass of tissue is formed
upon the ventral surface.
The superficial cells of both
sides of the prothallium have
a well-marked cuticle. Nu-
merous brown rhizoids,
which, like those of the sim-
pler Liverworts, are uni-
cellular and thin - walled,
grow out from the cells of
the lower surface, especially
from the broad midrib. The
full-grown prothallium in
M. Douglasii is sometimes a
centimetre or more in length
(Fig. 151), and tapers from the broad heart-shaped forward
end to a narrow base. In Angioptcris (Farmer (3) ) it is more
nearly orbicular. In both genera it is dark-green in colour,
looking very much like the thallus of Anthoceros Iccvis, and like
this too is thick and fleshy in texture. A broad midrib extends
for nearly the whole length of the thallus and merges gradually
into the wings, which are also several-layered, nearly or quite
to the margin.

The prothallium of Dancra (Brebner (i)) resembles more

Fig. 150. — Marattia Douglasii. A, Horizon-
tal section of prothallium apex, with two
initials, Xi6o. B, Longitudinal section
of a similar growing point; d, dorsal; v,
ventral segment.

VIII

MARATTIALES

277

closely that of Angioptcris, than that of MarafticL The rhizoids
are multicellular, recalling those of the gametophyte of

Botrychium.

The very old prothallia sometimes branch dichotomously
(Fig. 151, B, C), and the process is identical with that in the
thallose Hepaticse. The two growing points are separated by
a median lobe in the same way, and the midrib with the sexual

FiG. 151.— Mora«ta Douglash. A, ProthalHum about one year old, X2; B, the same
prothallium about a year later, showing a dichotomy of the growing point; C, the
same seen from below, showing two archegonial cushions ($) ; D, prothallium with
young sporophyte, X4; E, a somewhat^ older one, seen from the side; r. the pri-
mary root.

organs upon it forks with it, exactly as we find, for example,
the antheridial receptacle forking in Fimbriaria Californica
(Fig. I, A). Besides this form of branching, which is not
common, adventitious buds are produced upon the margin of
the thallus very frequently. These grow in precisely the same
way as the main prothallium, and after a time may become

278 MOSSES AND FERNS chap.

detached and form independent plants; or they may develop
sexual organs (mainly antheridia) while still connected with
the mother plant. The duration of the prothallium is apparently
unlimited, so long as it remains un fecundated. The writer
kept prothallia of Marattia Douglasii for nearly two years,
during which they grew continuously and finally reached a
length of over two centimetres. At the end of this time they
were growing vigorously, and there was nothing to'indicate the
slightest decrease in their vitality.

The prothallia are monoecious, although not infrequently
the smaller ones bear only antheridia. The latter always
appear first, and are mainly found upon the lower side of the
midrib, but may also occur upon the upper side. The arche-
gonia are confined to the lower surface of the midrib, and as
they turn dark brown if they are not fertilised, they are visible
to the naked eye as dark brown specks studding the broad thick
midril). Both antheridia and archegonia resemble closely those
of Ophioglossum.

The Sex-organs

The antheridium arises from a single superficial cell which
first divides into an inner cell, from w^hich the sperm cells are
derived, and an outer cover cell (Fig. 152, A). The latter
divides by several curved vertical walls (Figs. E-G) Avhich
intersect, and the last wall cuts off a small triangular cell (o),
which is thrown off when the antheridium opens, and leaves
an opening through which the sperm cells are ejected. The
inner cell, by repeated bipartitions, gives rise to a large number
of polyhedral sperm cells. Before the full number of these is
complete, cells are cut off from the adjacent prothallial cells,
which comi)letely enclose the mass of sperm cells. As in other
Archegoniates, the nucleus of the sperm cell, after its final
division, shows no nucleolus. The first sign of the formation
of the spermatozoid that could be detected was an indentation
upon one side, followed by a rapid flattening and growth of the
whole nucleus. The cytoplasmic prominence which, according
to Strasburger, is the first indication of the formation of the
spermatozoid, could not be certainly detected. The main part
of the spermatozoid, stains strongly with alum-cochineal, and
is sharply differentiated against the colourless cytoplasm, and

VIII

MARATTIALES

279

for some time shows the characteristic nuclear structure. The
origin of the ciha was not clearly made out, but there is little
question that they arise from a blepharoplast as in other cases
that have been more recently investigated. The free sperma-
tozoid (Fig. 152, I), is a flattened band, somewhat blunt behind
and tapering to a fine point in front ; attached to a point just
back of the apex are several fine cilia. The body shows only
about two complete coils.

Fig. 152. — Marattia Douglasii. Development of the antheridium. A-D, Longitudinal
section, X515; E-G, surface views, X257; H, ripe sperm cells; I, free spermato-
zoids, X1030; o, operculum.

The youngest archegonia are met with some distance back
of the growing point, and apparently any superficial cell is
potentially an archegonium mother cell. The latter divides
usually into three superimposed cells (Fig. 153, A), of which
the lowest (b) forms the base of the archegonium. The basal
cell, however, may be absent in Marattia Douglasii, as is also
the case in Angioptcris and Dancca. From the middle cell by a
transverse division are formed the primary neck canal cell and

28o

MOSSES AND FERNS

CHAP.

the central cell. Each of these divides again transversely. In
the upper one this division is often incomplete and confined to
the nucleus; but in the central cell the division results in the
separation of the ventral canal cell from the ovum. Before the
separation of the primary neck canal cell from the central cell,
the cover cell divides as in the Liverworts into four cells by
intersecting vertical walls, and each of these cells by further
obliquely transverse walls forms a row of about three cells, and
these four rows compose the short neck. The canal cells are

Fig. 153. — Marattia Douglasti. AD, Development of the archcgonium, X450; E, sec-
tion of the fertilised egg, showing the spermatozoid (sp) in contact with its nu-
cleus, X485; F, successive longitudinal sections of a young embryo, X225; b, b,
the basal wall; the arrow points towards the archegonium.

very broad and the egg cell small, so that after the archegonium
opens it occupies but a small part of the cavity left by the
disintegration and expulsion of the canal cells. Before the
archegonium is mature, flat cells are cut off from the adjacent
prothallial tissue as in the antheridium (Fig. 153, D). The
neck of the ripe archegonium projects but little above the
surface of the prothallium, and in this respect recalls both the
lower OphioglossacccX and the Anthocerotes. The ripe ovum
is somewhat elliptical, and slightly flattened vertically. Its

VIII

MARATTIALES

281

Upper third is colourless and nearly hyaline. This is the
''receptive spot," and it is here that the spermatozoid enters.
The nucleus is of moderate size, and not rich in chromatin; a
small but distinct nucleolus is present. The spermatozoid
retains its original form after it first enters the egg, and until it
comes in contact with the membrane of the egg nucleus. It
afterwards contracts and assumes much the appearance of the
nucleus of the sperm cell previous to the differentiation of the
spermatozoid. The two nuclei then gradually fuse, but all the
different stages could not be traced. Before the first division

Fig. i54.-yMarattia Douglasii. Embryogeny. A, Longitudinal; B, transverse sections
of embryos, X215; C, vertical section of an older embryo, showing its position in
the prothallium, X72; st, the stem; pr, prothallium; D, upper part of the same
embryo, X215.

takes place, however, but one nucleus can be seen, and this
much resembles the nucleus of the unfertilised egg. It is prob-
able that the nucleus of the spermatozoid really penetrates the
cavity of the egg-nucleus as has been shown to be the case in
Onoclea. ( See Shaw ( i ) ) •

The Embryo — (Farmer (3); Jonkman (3))

After fertilisation the egg enlarges to several times its
original size before dividing. The first (basal) wall is trans-

282

MOSSES AND FERNS

CHAP.

verse and is followed in each half by two others, the median and
octant walls. The nearly globular embryo is thus divided into
eight similar cells, each having the tetrahedral form of a globe
octant. The next divisions are not perfectly understood, and
evidently are not absolutely uniform in all cases. All the
octants at hrst show nearly uniform growth, and the embryo
retains its nearly oval form (Figs. 153, F, 154, A). The first
division in the octants is essentially the same, and consists in a
series of anticlinal walls, before any periclinal walls appear, so
that we may say that for a short time each octant has a distinct
apical growth, and there are eight growing points. The older

Fig. 155. — Marattia Douglasii. A, Cross-section of the young sporophyte at the junc-
tion of the cotyledon and stem; st, the apical meristem of the stem, X215; B, the
stem apex of the same, X430; C, longitudinal section of the stem apex of a plant
of about the same age, X215; tr, the primary tracheary tissue; r^, the second
root.

embryo shows an external differentiation into the first leaf,
stem, and root, but the foot is not clearly limited at first. The
basal wall separates the embryo into two regions, epibasal and
hypobasal. From the former the cotyledon and stem apex
are derived, from the latter the root and foot.

The cotyledon arises from the anterior pair of epibasal
octants, which are in the Marattiacere, unlike all the other Ferns,
turned away from the archegonium opening. In the earliest
stages where the cotyledon is recognisable, no single apical cell
could be made out, and later the growth is very largely basal.

^III

MARATTIALES

283

At first the growth is nearly vertical, but it soon becomes
stronger upon the outer side, and the leaf rudiment bends
inwards. At this stage the different tissues Ijegin to be dis-
tinguishable. Somewhat later the tip of the cotyledon becomes
flattened, and still later there is a dichotomy of this flattened
part which thus forms a fan-shaped lamina (Fig. 157). The

Fig. 156, — Marattia Douglasii. A, B, C, Three transverse sections of a root from the
young sporophyte; A shows the apical cell (.r) , X215; D, longitudinal section of a
similar root, X260; E, vascular bundle of the root, X260.

first tissue to be recognised is the vascular bundle which
traverses the centre of the petiole and at first consists of uni-
form thin-walled elongated cells (procambium). This forma-
tion of procambium begins in the centre of the embryo and
proceeds in three directions, one of the strands going into the

284 MOSSES AND FERNS chap.

cotyledon, one in an almost opposite direction to the primary-
root, and a very much shorter one to the young stem apex,
Avhich lies close to the base of the cotyledon. The outer layer
of cells of the cotyledon forms a pretty clearly defined epidermis
separated from the axial procambium strand by several layers
of young ground-tissue cells.

The apex of the young stem is occupied in some cases, at
least, by a single apical cell, which probably is to be traced back
directly to one of the original octants of the embryo. Whether
this is always the case in the youngest stages cannot be de-
termined until further investigations are made. Farmer (3)
was unable to make out a single initial in Angiopteris, which
otherwise agrees closely with Marattia. Dancca, according to
Brebner ( i), shows a single initial cell at the stem-apex, as well
as that of the primary root.

The studv of the root w^as confined mainly to the older
embryos, and although some variation is noticed, it is pretty
certain that there is a single apical cell, not unlike that found
in the Ophioglossacea^. \\niether this can be traced back to
one of the primary hypobasal octants, it is impossible now to
say; but Farmer's statement that in Angiopteris there is at first
a three-sided apical cell would point to this. Unfortunately
my own preparations of Marattia were too incomplete to decide
this point in the latter. In the older root the form of the apical
cell was usually a four-sided prism, from all of Avhose faces
segments were cut off, although sometimes an approach to the
triangular form found in the Ophioglossacese was observed.

The foot is much less prominent than in Botrychinm, and
in this respect the Marattiace?e are more like Ophioglossum
(Mettenius (2), PI. xxx). In Marattia all the superficial cells
of the central ree^ion of the embrvo become enlare^ed and act as
absorbent cells for the nourishment of the growing embryo.

As the embryo grows, the surrounding prothallial tissue
divides rapidly, and a massive calyptra is formed which com-
pletely encloses the young sporophyte for a long time. Owing
to the position of the cotyledon and stem, which grow up
vertically through the prothallium, a conspicuous elevation is
formed upon its upper side, through which the cotyledon finally
breaks. A similar elevation is formed by tlie calyptra upon
the lower side, through which the root finally penetrates, but nol
until after the cotyledon has nearly reached its full development.

/Ill

MARATTIALES

285

The proihallium does not die immediately after the young
sporophyte becomes independent, but may remain ahve for
several months afterwards, much as in Botrycliiuui.

The first tracheary tissue arises at the junction of the bun-
dles of the cotyledon, stem, and root. These primary tracheids
are short and their walls are marked wath reticulate thickenings.
From this point the development of the tracheary tissue, as v^ell
as the other elements of the bundles, proceeds toward the apices
of the young organs. The formation of the secondary
tracheids is ahvays centripetal.

Fig. 157. — A, Young sporophyte of Danaca siinplicifolia, still attached to the gameto
phyte, pr; X3; B, an older sporophyte of the same species; C, gametophyte of
Angiopteris evecta, with the young sporophyte. (A, B, after Brebner; C, after
Farmer.)

Jeffrey (3) states that in the young sporophyte of several
species of Dancca examined by him, the stele has the form of a
tube with both internal and external endodermis and phloem.
Both internal endodermis and phloem tend to disappear in the
later-formed part of the stem. The tubular central cylinder is
interrupted by the foliar gaps, and later there are formed
medullary vascular strands, and the vascular system gradually
assumes the very complicated form met with in the older
sporophyte. Brebner (3) states that in Dancca simplicifolia the

286 " MOSSES AND FERNS chap.

primary vascular axis is a simple concentric stele, which is later
replaced by a cylindrical stele like that of D. alata.

Short hairs with cells rich in tannin, and staining strongly
with Bismarck-brown, occur sparingly upon the leaves and
stem of the young sporophyte.

The fully-developed cotyledon has the fan-shaped lamina
somewhat lobed, and the two primary veins arising from the
forkino; of the orii^inal vascular bundle usuallv fork once more,
so that the venati(Mi is strictly dichotomous in character. The
nearly cylindrical petiole is deeply channeled upon the inner
side, and the single axial vascular bundle is almost circular in
section. \Miile the crescent-shaped mass of tracheary tissue is
completely surrounded by the phloem, the latter is much more

strongly developed
upon the outer side,
and the bundle ap-
proaches the collateral
form of OpJiioglos-
sum. Indeed, if the
tannin cells, which are
found here, belong to
the cortex, as Farmer
asserts to be the case
in Angioptnis, the
bundle would be truly
„ . , r , , • f *, collateral, as these tan-

FiG. 158. — Horizontal section of the lamina of the ' ^

cotyledon of M. Dougiasii. X260. uiii cclls are mimcdi-

ately in contact with
the tracheids. The lamina of the cotyledon is similar in struc-
ture to that of the later leaves, and differs mainly in the smaller
development of the mesophyll. The smaller veins have the
xylem reduced to a few (1-3) rows of tracheids upon the
upper side of the collateral bundle. Stomata of the ordinary
form occur upon the lower side of the leaf.

In Angioptcris (Fig. 157, C) and Dancca (Fig. 157, A),
the cotyledon is spatulate in outline with a distinct midrib.

As the root finally breaks through the calyptra and pene-
trates into the earth, numerous fine unicellular root-hairs
develop from the older parts, but the tip for some distance
remains free from them. Owing to the numerous irregularities
in the cell divisions, the exact relation of the tissues of the

VIII

MARATTIALES

287

'Z^

X^"^F

older parts of the root to the segments of the apical cell is

impossible to determine, and evidently is not always exactly

the same. The root-cap is derived mainly from the outer

segments of the apical cell, but also to some extent from the

outer cells of the lateral segments; and the central cylinder,

where the base of the

apical cell is truncate, is ^ "^ St A.

formed mainly from the

basal segments, but in

part as well from the

inner cells of the lateral

segments.

The vascular cylin-
der of the root is usually
tetrarch. At four points
near the periphery small
spiral or annular
tracheids appear, and
from them the formation
of the larger secondary
tracheids proceeds
toward the centre. The
phloem is made up of
nearly uniform cells with
moderately thick colour-
less walls. A bundle-
sheath is not clearly to be
made out (Fig. 156).

The cotyledon is des-
titute of the stipules
found in the perfect
leaves of the Marat-
tiacese, but they are well
developed in the third
leaf, where they form
two conspicuous append-
ages clasping the base

of the next youngest leaf. The edges of these stipules are
somewhat serrate, and the edges of the two meet, much like two
bivalve shells. The strictly dichotomous character of the
cotyledon is gradually replaced in the later leaves by the pinnate

Fig. ISO- — Marattia Douglasii. A, Longitudinal
section of the young sporophyte, showing the
distribution of the vascular bundles, X6; /,
leaves; st, stem apex; r, a root; f, the foot;
B, young sporophyte with the prothallium
{pr), still persisting.

288

AIOSSES AND FERNS

CHAP.

arrangement, both of the divisions of the leaf and the venation.
This is brought about in both cases by an unequal dichotomy,
by which one branch develops more strongly than the other,
so that the latter appears lateral. With the assumption of the
pinnate form the leaf also develops the wings or appendages
upon the axis between the pinn?e. In the fully-developed leaves
of the mature sporophyte, the last trace of this is seen in the
ultimate branching of the veins, which is always dichotomous.
The second root arises close to the base of the second leaf,
and at first there seems to be one root formed at the base of
each of the young leaves ; in the older sporophyte the roots are

Fig. i6o. — A, Longitudinal section; B, transverse section of roots from older sporo-
phyte of M. DoHglasii, showing apparently more than one initial cell, X200.

more numerous. Holle states that this is not the case in
Marattia, where only one root is formed for each leaf, in
Angioptcris two. This, however, requires confirmation in the
older plants. As the roots become larger it is no longer pos-
sible to distinguish certainly a single initial cell. The adjacent
segments themselves assume to some extent the function of
initials, and thus in place of the single definite apical cell a group
of apparently similar initials is formed, which takes its place
(Fig. 160). This seems to be in some degree associated with
die increase in size of the roots. ^

^ It is possible that a single initial may be present even here, but the
great similarity of the central group of cells makes this exceedingly difficult
to determine.

VIII

MARATTIALES

The Adult Sporophyte

289

According to Holle (1. c. p. 218) the four-sided apical cell
found in the stem of the young sporophyte of Marattia is re-
tained permanently, but in Augiopteris this is not the case, as
in the older sporophyte a single apical cell is not certainly to be
made out. Bower ((11) p. 324) comes to the same conclusion

A. C.

Fig. 161.— a, Section of the stipe of Angiopteris evecta, natural size; B, section of the
rachis of the ultimate division of the leaf of Marattia alata, XiS; '». mucilage
ducts; C, collenchyma from the hypodermal layer of the rachis, X250; D, part
of the vascular bundle of B, X250; t. tannin cells.

as Holle, although in an earlier paper (2) he attributes a single
apical cell to the stem of Angiopteris. The stem in both genera
becomes very massive, but its surface is completely covered by
the persistent stipules.

The structure of the stem in Angiopteris has recently been
carefully investigated by Miss Shove ( i ) who has also reviewed
19

290

MOSSES AND FERNS

CHAl

the earlier literature upon the anatomy of the Marattiacese. In
the stem of Angioptcris there is a reticulate vascular cylinder
like that of Opiiioglossiim, but within this are three or four
similar concentrically arranged "meshed zones," and a single
central strand. In the specimen examined by Miss Shove the
stem was oblique, and the meshes of the vascular cylinders were
much closer upon the dorsal than upon the ventral side.

The majority of the roots originate from the inner zones,
but thev may also arise from the outer ones. The leaf-traces
all come from the outer zone — at least such w^as the case in the
specimen studied by Miss Shove. It is stated that Mettenius
(3), found that the leaves also received strands from the second
vascular zone. The concentric vascular cylinders are connected
by branches ("compensating segments"), wdiich pass out to

Fig. 162. — Dancea alata. A, Transverse section of vascular bundle of the petiole, X17S',
X, tracheary tissue; t, tannin cells. B, Cross-section of a mucilage duct, Xi75-

the gaps formed by the departure of the leaf-traces. Marattia
(Kiihn (2)), closely resembles Angioptcris in its stem struc-
ture, but it has but two vascular cylinders outside the central
strand, while Kanlfussia has but a single one. The bundles,
are, according to Holle ( (2), p. 217) concentric, but the phloem
more strongly developed upon the outer side.

The thick petioles of the full-grown leaves are traversed by
very numerous vascular bundles, which at the base give off
branches that supply the thick stipules within which they
branch and anastomose to form a network. These bundles in
Angioptcris (Fig. 161, A) are arranged in several circles, or
according to I)e \'riese ( i ) and Harting, the central ones form
a spiral. In the rachis of the last divisions of the leaves, how-

\^III

MARATTIALES

291

ever, both of Maraffia and Angioptcris, there is but a single
axial bundle, as in the petiole of the cotyledon.

Fig. 167, B shows a cross-section of a pinnule from a large
leaf of A. evccta, which has much the same structure as that of
Marattia. The central vascular bundle is horse-shoe shaped in
section, and shows a central mass of large tracheids with retic-
ulate or scalariform markings, surrounded by the phloem made
up of very large sieve-tubes much like those of Botrychhim,
and with these are the ordinary protophloem cells and bast
parenchyma. A distinct bundle-sheath is absent, as, according
to Holle, it is from all the bundles in both Marattia and An-
giopteris, except those of the larger roots. The bulk of the

Fig. 163.— a, Section of a large root of Angioptcris evecta, X14; m, mucilage duct;
B, part of the central cylinder, X about. 70; en, endoderrnis.

ground tissue is composed of large parenchyma cells, but on
both sides just below the epidermis is a band of colourless cells
which resemble exactly the collenchyma of Phanerogams. In
the base of the petiole this becomes harder and forms a colour-
less sclerenchyma, which in Dancca is replaced by brown scleren-
chyma like that of the true Ferns. In the lamina of the leaf in
Angiopteris too, the arrangement of the tissues is strikingly like
that of the typical Angiosperms. A highly-developed palisade
parenchyma occupies the upper part of the leaf beneath the epi-
dermis, which bears stomata only on the lower side of the leaf.
The rest of the mesophyll is composed of the spongy green
parenchyma found in the other Ferns. The smaller veins both
here and in Marattia have collateral bundles.

292 MOSSES AND FERNS chap.

Short hairs occur upon the young sporophyte, and upon the
older plant there may be developed scales (paleae) similar to
those found in the leptosporangiate Ferns.

The base of the stipe, as well as that of the rachis of the leaf-
segments, is enlarged, closely resembling the "pulvinus" of a
leguminous leaf. The stalk breaks at this place, leaving a clean
scar. The smaller leaflets separate in the same way from the
rachis.

The Marattiacese all develop conspicuous mucilage ducts
(Figs. 162, 163, m) and gum canals, very much like those
occurring in the Cycads (Brebner (2)). These ducts are of
two kinds. The first type is *'schizogenic," i. e., of intercellular
origin, the secretory cells surrounding the intercellular canal.
The ducts of the second type are formed from the breaking
down of rows of tannin-bearing cells, which thus form irregular
ducts, not unlike certain milk-tubes of the higher plants.

Upon the stipules and stipe there are often present lenticel-
like structures ("Staubgriibchen" of German authors). These
originate beneath stomata, in much the same way as the ordi-
nary lenticels ; but the cells below the opening of the lenticel are
not cork-cells, but small, thin-walled cells, which separate and
dry up, forming a dusty powder.

Intercellular rod-like organs, composed mainly of calcium-
pectate, are of common occurrence. There may also occur
silicious deposits, and crystals of calcium-oxalate have been ob-
served in Angioptcris (See Bitter ( i ) ).

The Sporangium

The sporangia of the Marattiaceae differ most markedly
from the Ophioglossaceae in being borne on the lower side of the
ordinary leaves, and not on special segments. Except in
Angioptcris, they form synangia, whose development has been
especially studied in Marattia. Luerssen (7) describes the
process thus : 'Tn Marattia the first differentiation of the spo-
rangium begins while the young leaf is still rolled up between the
stipules of the next older one. The tissue alK)ve the fertile vein
is more strongly developed than the adjoining parenchyma, and
forms an elevated cushion parallel with the vein. This is the
receptacle, which develops two parallel ridges, separated by a
cleft. These two ridges grow up until they meet, and their
edges grow together and completely close the cleft which lies

VIII

MARATTIALES

293

between. In each half there are (Hfferentiated the separate
archesporial groups of cells corresponding to the separate
chambers found in the complete synangium." The whole
process takes, according to his account, about six months.
Luerssen was unable either in Marattia or Angiopteris to trace
back the archesporium to a single cell, which Goebel (3) claims
is present in the latter.

In Angiopteris the process begins as in Marattia, but at a
period when the leaf is almost completely developed and

Fig. 164. — Angiopteris cvecta. Development of the sporangium. A, Vertical section
of very young receptacle; B, similar section of an older sporangium in which the
archesporium is already developed (after Goebel) ; C, longitudinal section of an
almost fully-developed sporangium, showing the persistent tapetal cells (0; r, the
annulus, X75.

unfolded. The first indication of the young sorus is the
formation of an oblong depression above a young vein, and
about the border of this are numerous short hairs, which as a
rule are absent from the epidermis of the leaf (Fig. 164, A).
The placenta is formed as in Marattia, but instead of the two
parallel ridges that are found in the latter, the young sporangia
arise separately, much as in Botrychiiim. As in the latter too,
Goebel states that the archesporium can be traced to a single

^94

MOSSES AND FERNS

CHAP.

hypodermal cell in the axis of the young sporangium. This
cell divides repeatedly, but apparently without any definite
order, and the division of the spores follows in the usual way.
From the cells about the archesporium tapetal cells are cut off,
but these do not disappear, as Goebel (3) asserts, but persist

until the sporangium is mature. The growth is

greater

upon the outer side, which is
strongly convex, while the
inner face is nearly flat.

A section of the nearly
full-grown sporangium ( Fig.
164, C) shows that the wall
upon the outer side is much
thicker, and is composed for
the most part of three layers
of cells, of which the outer
in the ripe sporangium have
their outer walls strongly
thickened. The top of the
sporangium and the inner
wall are composed of but one
layer of cells (exclusive of
the tapetum), which are flat
and more delicate than those
upon the outer side. Near
the top on its outer side is a
transverse line of cells with
thickened darker walls, which
project somewhat above the
level of the others. This is
T, ^ ,, ■ . ■ . ^ the annulus or rinqf. and re-

iMG. 165. — Marattia fraxinea. A, Transverse ^

section of young synangium, X225; B, SCmblcS closclv that of Os-
similar section of an older synangium. ^„;^;; J^^ Lining tllC Wall is a

X112; X, X,
Bower.)

the tapetal cells.

(After " ^

layer of very large thin-

walled cells which form the
tapetum. This in Augiopfcris remains intact until the spores
are divided. Whether it disappears before the dehiscence of
the sporangium was not determined. The contents of these
cells, which are very much distended, and evidently actively
concerned in the growth of the forming spores, contain very
few granules, but are multinucleate in many cases. Whether

VIII

MARATTIALES

295

this condition is due to a coalescence of originally separate cells,
or what seems more likely, arises simply from nuclear division
in the young tapetal cells, without the formation of cell walls,
was not decided. The young spore tetrads, at this time, are
embedded in an apparently structureless mucilaginous matter,
which stains uniformly with Bismarck-brown. This mucilage
apparently is secreted by the tapetal cells for the nourishment
of the spores.

Bower (17) has recently made a very complete study of the
development of the sporangium in all the genera except

Fig. 166. — A, Transverse section of three synangia of Danaa alata, X15; B, horizontal
section of a synangium, showing the numerous loculi, X15; C, vertical; D, hori-
zontal section of a synangium of Kaulfiissia cesculifolia, XiS- (C> D. after
Bower.)

Archangiopteris. He finds in all of them that the sporogenous
tissue of each sporangium (or loculus), can usually be traced
to a single mother-cell, although .there may be exceptions to this

rule.

In all cases the tapetum arises from the tissue adjacent to
the archesporium, and not from the outer cells of the sporog-
enous complex. In this respect the Marattiacese resemble more
nearly Helminthostachys or Botrychimn than they do Ophio-

glossiim.

In Dancra and Kmilfitssia there is no mechanical tissue rep-
resenting an annulus. The dehiscence is accomplished by a

296

MOSSES AND FERNS

CHAP;

t) •

•M

~f q3

t-i

/-^

•i^

«J

•^

»1

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VIII

MARATTIALES

297

shrinking of the cells on either side of the opening slit. The
latter in Dancra is short, and finally appears like a circular pore,
but is really not essentially different from that in Kaulfiissia and
Marattia. In the latter there is a mechanical tissue which
causes the two valves of the synangium to gape widely at ma-
turity, and the dehiscence of the individual loculi is effected by

Fig. i68.—Archang{opteris Henryi. A, Entire sterile leaf, reduced; B, base of stipe,
showing the stipules; C, part of a ^fertile pinna, of the natural size. (After
Christ & Giesenhagen.)

the contraction of thinner walled cells surrounded by firmer

tissue.

The number of spores produced in each loculus is approx-
imately 1750 for Dancra, 7500 for Kanlfussia, 2500 for Marat-
tia, and 1450 for Angiopteris.

Bower's account and figures of Angiopteris differ from the
specimens examined by the writer in the greater thickness of

298

MOSSES AND FERNS

CHAP.

the sporangium wall. This may have been due to different
conditions under which the plants were grown, or to a possible
difference in the species.

There is frequently found surrounding the synangium, hairs
or scales which form a sort of indusium (Fig. 165). In
Dancra, the leaf tissue between the synangia grows up as a
ridge, with expanded top overarching them. This ridge in sec-
tion appears T-shaped (Fig. 166, A).

Fig. 169. — A small plant of Dancca alata, XV2; st, stipulei.

Classification of the Marattiace^

The living Marattiaceje (Bitter (i)) may be divided into
four sub-families, of which the first, Angiopterideae includes
two genera, Angioptcris and Archangioptcris, while the others,
Marattiese, Kaulfussiese, and Danaease, contains each but a
single genus.

VIII

MARATTIALES

299

Marattia includes about twelve species of tropical and sub-
tropical Ferns, both of the Old World and the New. Kaiil-
fiissia includes but a single species, belonging to southeastern
Asia. The synangia are scattered over the lower surface of
the palmate leaf, and are circular, with a central space into
which the separate loculi open by a slit, as in Marattia. Kaitl-
fussia is characterised by very large pores upon the lower side
of the leaf. A study of the development of these shows that at
first they are perfectly normal in form, and that the large round
opening is a secondary formation, the two guard cells of the
young stoma being torn apart, and disappearing almost entirely
in the older leaf.

Fig. 170. — Datiwa alata. A, Sterile; B, fertile pinna, X i '/4 ; C, cross-section near the
base of the petiole, X6; set, selerenchyma; m, mucilage ducts; vb, vascular bundles.

The genus Dancea is exclusively American and comprises
about fourteen species of small or middle-sized Ferns. D. sim-
plicifoUa has a simple lanceolate leaf, the others have once-
pinnate leaves. The fleshy stipe is often characterised by con-
spicuous swellings. The venation of the leaves (Fig. 170) is
much like that of Angioptcris and some species of Marattia.
The fertile pinnae are decidedly contracted, and the elongated
synangia almost completely cover their lower surface.

The stem (Fig. 169) is a horizontal fleshy rhizome, the
leaves arranged in two ranks upon the upper side. The leaf-

300

MOSSES AND FERXS chap.

base has a pair of conspicuous stipules like those found in the
other genera.

Kaiilfussia ccsculifolia is the sole representative of the family
Kaulfussiej?e, and differs very much in habit from the other liv-
ing Marattiaceae. The rhizome and leaf arrangement are not
unlike those of Dancca, but the leaf is palmately divided, and the
venation is reticulate, while the synangia are scattered. The
synangium is circular, or broadly oval in outline. (Fig. i66).

The recently discovered Archangiopteris, (Fig. i68) is a
small Fern from southern China, which in habit resembles
Dancca. The sporangia, however, are more like those of
Angiopteris.

The Affinities of the Ensporangiate Filicinece

In attempting to determine the affinities of the members of
this group, many difficulties are encountered. First, and
perhaps most important, is the small number of species still
existing, which probably are merely remnants of groups once
much more abundant. This is certainly true of the Maratti-
aceae, and presumably is the case with the Ophioglossaceae as
well. In the former this is amply proven by the geological
record ; but in the others the fossil forms allied to them are
very uncertain, and as yet poorly understood. In the Ophio-
glossace?e the series from Ophioglossum through the simpler
species of Botrychiiiin to the higher ones, such as B. Virgin-
ianiini, is complete and unmistakable, but when points of con-
nection between these and other forms are sought, the matter
is not so simple.

Our still somewhat incomplete knowledge of the gameto-
phyte of the Ophioglossacea^ makes the comparison doubly
difficult. From the development of chlorophyll in the germi-
nating spore of B. Virginianuni, as well as from analogy with
other Ferns, it seems probable at any rate that the subterranean
chlorophylless prothallium is a secondary formation, but this
cannot be asserted positively until the development is much
better known than at present, and its relation to the green pro-
thallium of the IMarattiales and the thallus of the Hepaticae
must remain in doubt. The structure of the sexual organs and
development of the embryo point to a not very remote connection
with the former order, and in some respects also to the Antho-
cerotes.

VIII

MARATTIALES 30i

Ophioglossiun beyond question shows the simplest type of
sporangium of any of the Pteridophytes, and may be directly
compared to a form like Anthoccros. In both cases the arche-
sporium is hypodermal in origin, and is formed without any
elevation of the tissue to form separate sporangia. In Antho-
ccros, alternating with the sporogenous cells, are sterile cells
which divide the archesporium into irregular chambers contain-
ing the spores. A direct comparison may be drawn between
this and the origin of the archesporium in Ophioglossum,
especially in connection with Prof. Bower's discovery of a con-
tinuous band of sporangiogenic tissue in the latter. In some
species of Ophioglossum, too, the epidermis of the sporangium
has stomata as in Anthoccros. A comparison of these remark-
able points of similarity in the structure of the sporophyll of
Ophioglossum and the sporogonium of Anthoccros, together
with the very simple tissues of the former, led the writer
(Campbell (7) ) to express the belief that Ophioglossum, of all
living Pteridophytes, seemed to be the nearest to the Bryo-
phytes. Subsequent study of the eusporangiate Ferns has
strengthened that belief, and from a comparison of these with
Ophioglossum on the one hand and the Anthocerotes on the
other, it seems extremely likely that the latter represents more
nearly than any other group of living plants the form from
which the Pteridophytes have sprung, and that in the series of
the Filicinese at any rate, Ophioglossum comes nearest to the
ancestral type. Of course the possibility of Ophioglossum
being a reduced form must be borne in mind, and the sapro-
phytic habit of the prothallium may perhaps point to this ; still,
whatever may be its real character, there is little doubt that it
is the simplest of the Filicinese. The recent discovery of the
interesting O. simplex strengthens this view.

The resemblances between Ophioglossum and the Antho-
cerotes are not confined to the sporophyte. The sexual organs
— and this is true of all the eusporangiate Pteridophytes — show
some most striking similarities that are very significant. It
will be remembered that in the Anthocerotes alone among the
Bryophytes the sexual organs are completely submerged in the
thallus — the antheridia being actually endogenous. It will be
further remembered that in the eusporangiate Filicinese a
similar condition of things exists.

302

MOSSES AND FERNS chap.

In all the HepatiCcC the axial row of cells of the archegonium
terminates in the cover cell, which by cross-divisions forms the
group of stigmatic cells of the neck. In the Anthocerotes this
terminal group of cells is the only part of the archegonium neck
that is free, the lateral neck cells being completely fused with
the surrounding tissue. This arises from the archegonium
mother cell not projecting at all, but we have seen that in cross-
section a similar arrangement of the cells is presented to that
found in the young archegonium of other Hepatic?e. In the
Filicinese a similar state of affairs exists, but the divisions in the
mother cell are, as a rule, not so irregular. Still, c. g., Marattia,
it is sometimes easy to see that the mother cell (so-called) of
the archegonium is triangular when seen in cross-section, and
cut out by intersecting walls in exactly the same way as the
axial cell in the Bryophyte archegonium. In short, what is
ordinarily called the mother cell of the archegonium in the Ferns
is really homologous with the axial cell only of the young
archegonium of a Liverwort. A comparison of longitudinal
sections of the young archegonium of Marattia, for instance,
with that of Notothylas, will show this clearly. From this it
follows that the four-rowed neck of the Pteridophyte arche-
gonium does not correspond to the six-rowed neck of the
Bryophyte archegonium, but only to the group of cells formed
from the primary cover cell, and is a further development of this.
The relatively long neck of the archegonium in the more special-
ised forms, e. g., Botrychhim Virginianum, and especially the
leptosporangiate Ferns, must be regarded as a secondary de-
velopment connected probably with fertilisation. The shifting
of the archegonium to the lower surface of the gametophyte has
probably a similar significance. In B. Virginianum, however,
the archegonia are borne normally upon the upper side of the
thallus, as in the thallose Liverworts.

It is possible that a similar relation exists between the
antheridia of the eusporangiate Ferns and that of the Antho-
cerotes. In both cases the formation of the antheridium begins
by the division of a superficial cell into a cover cell and a central
one. The former divides only by vertical walls in the Marat-
tiaceae, but in Botrychiuin and the Anthocerotes it becomes
two-layered. In the latter the central cell may form a single
antheridium, or it may produce a group of antheridia, but in
the others it divides at once into a mass of sperm cells. By the

VIII

MARATTIALES 303

suppression of the wall in the antheridium of an Anthoceros
where only one antheridium is formed, there would be produced
at once an antheridium of the type found in Botrychiiun, and
by a further reduction of the division of the cover cell, by which
it remains but one cell thick, the type found in Marattia would

result.

Such an origin of the antheridium of the Filicineje is, at
any rate, not inconceivable, while not so obvious perhaps as the
resemblances in the archegonium, and is simply suggested as a
possible solution of a very puzzling problem.

The Marattiacese agree closely among themselves, and the
structure of the gametophyte is like that of the Ophioglossacese,
so far as the latter is known, and also offers most striking
resemblances to the Hepaticse. The long duration of the pro-
thallium, and its persistence after the sporophyte is independent,
as well as the long dependence of the latter upon the game-
tophyte, are all indications of the low rank of this order. The
sporophyte, while showing many points of resemblance to the
Ophioglossacese, still differs very much also, and in general
habit as well as the position of the sporangia comes nearer the
leptosporangiate Ferns. Of the Ophioglossacese, Helmintho-
sfacJiys on the whole approaches nearest to the Marattiacese, so
far as the general character of the sporophyte is concerned.
The venation of the leaves and dehiscence of the sporangia are
very similar to Angiopteris, and the green sterile tips to the
sporangial branches hint at a possible beginning of the lamina
of the sporophylls in the Marattiacese.

The synangia of Dancca show a certain analogy, at least,
with the sporangial spike of Ophioglossuni, and it is possible
that a comparison might be made between the leaf of 0.
pahnatiiin, with its numerous sporangial spikes, and a
sporophyll of Dancca (see Campbell (26) ) . Both archegonium
and antheridium of Ophioglos^sum pendulum are strikingly
similar to those of the Marattiacese.

While any relationship between these orders is necessarily a
remote one, nevertheless there are too many agreements in struc-
ture to make it at all probable that the Ophioglossacese and
Marattiacese have had an entirely independent origin.

In seeking a connection with the leptosporangiate Ferns
there are two points where this is possible. The higher species
of Botrychhun show an unmistakable approach to the leptospo-

304 MOSSES AND FERNS chap.

rangiate type. The archegonium neck projects much more than
in the other Eusporangiatae, and the vascular bundles in the
petiole are truly concentric. The venation of the leaves also
becomes that of the typical Ferns. The sporangia are com-
pletely free and smaller and more delicate, although truly
eusporangiate in development. In all these respects there is an
approach to Osniunda, unquestionably the lowest of the
leptosporangiate series. Hchninthostachys too may be almost
as well compared to Osinunda as to Angioptcris.

On the other hand, in the circinate vernation of the leaf as
well as the histology, in the roots and in the sporangia, the
Marattiaceae, especially Angioptcris, approach quite as close or
closer to the Osmundaceae than does Botrychium or Hehnintho-
sfacliys.

We may conclude, then, from the data at our disposal, that
the living eusporangiate Filicineae consist of a few remnants of
wide]}- divergent branches of a common stock, which formerly
was predominant, but has been supplanted by more specialised
modern types. From this primitive stock have arisen on the
one hand the leptosporangiate Ferns, and Cycads, on the other,
through Isoctcs, or some similar heterosporous forms, the
Angiosperms.

CHAPTER IX

FILICINE.E LEPTOSPORANGIAT^

The Leptosporangiatse bear somewhat the same relation to the
eusporangiate P^erns that the Mosses do to the Hepaticse, but
the disproportion in numbers is much greater in the former
case. While the whole number of living Eusporangiatse is
probably less than 50, the Leptosporangiatse comprise about
4000 species. In the former the differences between the
groups are so great that there is some question as to their near
relationship, while all the leptosporangiate Ferns show a most
striking similarity in their structure, and except for the presence
of heterospory in two families, might all be placed in a single
order. Carrying our comparison still further, we may com-
pare the Polypodiacege, which far outnumber all the others, with
the Bryales among the Mosses. Both groups are apparently
modern specialised types that have supplanted to a great extent
the lower less specialised ones.

The distribution of the leptosporangiate Ferns, too, offers
some analogy with the Mosses. While the eusporangiate
Ferns are few in number of species, they are for the most part
also restricted in numbers of individuals. The Leptosporan-
giates, on the other hand, occur in immense numbers, especially
in the tropics, where they often form a characteristic feature of
the vegetation. This is true to a limited extent in temperate
regions also, where occasionally a single species of Fern, e. g.,
Pteris aqiiilina, covers large tracts of ground almost to the ex^
elusion of other vegetation. A somewhat prevalent idea that
the Ferns of to-day form merely an insignificant remnant of a
former vegetation is hardly borne out by the facts in the case.
Any one who has seen the wonderful profusion of Ferns in a
20 305

3o6 • MOSSES AND FERNS chap.

tropical forest, and the enormous size to which many of them
grow, is very quickly disabused of any such notion.

The fossil record is also extremely instructive as bearing on
this point. According to Solms-Laubach (2) there is but one
certainly authentic case from the Carboniferous rock which can
be regarded certainly as a leptosporangiate form, all of the
other sporangia discovered being of the eusporangiate type. In
the later formations the Leptosporangiates increase in number,
but according to Luerssen ((7) II, p. 574) undoubted Poly-
podiacese are not found before the Tertiary, where a number of
living genera are represented.

Potonie (3) cites several examples of Palaeozoic Ferns
probably allied to the lower leptosporangiate families, but the
number is very small compared to the eusporangiate types.

Except in the few heterosporous forms there is, on the
whole, great uniformity in the gametophyte. The most
marked exception to this is the filamentous protonema-like pro-
thallium of some species of TricJioniancs and Sclii:;cca. Except
in these, however, the germinating spore, either directly or after
forming a short filament, produces normally a flat, heart-
shaped prothallium, growing at first by a two-sided apical cell,
the prothallium being at first one cell thick, but later producing
a similar cushion to that found in Maraffia but less prominent,
and the wings always remain one cell thick. Upon the lower
side of the cushion are produced the archegonia, which have
always a projecting neck, sometimes straight, but more com-
monly bent backward. The antheridia are produced upon the
same prothallium as the archegonia in most forms, but a few
species of Ferns are dioecious, and usually there are small male
prothallia in addition to the large hermaphrodite ones. The
antheridia, like the archegonia, always project above the surface
of the prothallium.

The first divisions in the embryo always divide it into
regular quadrants, and the young members always grow from
a definite apical cell, which, with the possible exception of some
of the Osmundaccte, is also found at the apex of the later roots
and always in the stem. In size the sporophyte varies ex-
tremely. In some of the smaller Hymenophyllace?e the creep-
ing stem is not thicker than a common thread, and the fully-
developed leaves scarcely a centimetre in length. The other
extreme is offered by the giant tree-ferns belonging to the Cya-

IX FILICINEM LEPTOSPORANGIAT^ 307

theacese, e. g., Alsophila, Cyathea, Cibotium. The leaves are
in most cases compound, and either firm and leathery in texture,
or in the delicate Hymenophyllace?e have the lamina reduced to
a single layer of cells, so that in texture it recalls a moss leaf.
With the single exception of the Salviniacece the leaves are
always circinate in the bud. The surface of the stem and leaves
is frequently provided with various epidermal outgrowths,
scales and hairs, which show a strong contrast to the mostly
glabrous Eusporangiat^e. The vascular bundles are, both in
the stem and petioles, of the concentric type with a very distinct
endodermis, and in the older parts of both stems and leaves
parts of the ground tissue are often changed into thick-walled
and dark-coloured sclerenchyma. In the liner veins of the leaf
the vascular bundles are reduced in structure and more or less
perfectly collateral.

The sporangia are extremely uniform in structure through-
out the group. They can be traced back to a single epidermal
cell, in most cases developed from the lower side of the un-
modified sporophylls, as in the Marattiacese. They are always
more or less distinctly stalked, and grow for a time from a
pyramidal apical cell, wdiose growth is stopped by the formation
of a periclinal wall (Fig. 190). The central tetrahedral cell
has first a layer of tapetal cells cut ofT from it, and the inner cell
then forms the archesporium. No sterile cells are formed in
the archesporium, but all the cells (except in the macro-
sporangium of the Hydropterides) develop perfect spores.*
The ripe sporangium is provided, except in the Hydropterides,
with an annulus or ring of thickened cells, which assists in its
dehiscence, and forms the most characteristic structure of the
ripe sporangium.

Non-Sexual Reproduction

In a few of the Ferns special non-sexual reproductive
bodies, buds of different kinds, occur upon the prothallium,
which thus may have an unlimited growth. Such buds may
have the form of ordinary branches, or they are of a special
form. Buds of the latter class occur, sometimes in great num-
bers, in certain Hymenophyllaceae, where they are formed upon
the margin of the prothallium, to which they are attached by
short unicellular pedicels from which they readily become de-

3o8

MOSSES AND FERNS

CHAP.

tached. In this way, as well as by the separation of ordinary
branches, the prothallia of some species of Hymenophyllum
form dense mats several inches in diameter, which look exactly
like a delicate Liverwort. A most remarkable case is that of
Anogrmiinic Icptophylla, examined by Goebel (i). The pro-
thallium multiplies extensively by buds, some of which form
tuber-like resting bodies, by which the prothallium becomes
perennial. The sporophyte in this species is annual and dies as
soon as the spores ripen. The archegonia are borne on special
branches of the prothallium, which penetrate into the ground
and lose their chlorophyll. Goebel ((lo) p. 245) suggests

Fig. 171. — A, Prothallium of Pteris crettca, with the sporophyte, sp, arising as a veg-
etative bud; B, apex of the root of Asplenium esculentum, developing into a leafy
shoot. (A, after De Bary; B, after Rostowzew.)

what seems very probable, that the subterranean prothallium
of the Ophioglossaceae may be of this nature, and the fact that
in Botrychium Virginiamim the germinating spore develops
chlorophyll would point to this.

Apogamy and Apospory

Apogamy, or the development of the sporophyte from the
prothallium as a vegetative bud, was first discovered by Farlow
(i) and later investigated by De Bary (2), Leitgeb (13), and
Sadebeck (6). It is known at present in Pteris Cretica, As-

FILICINE^ LEPTOSPORANGIATJE

309

a... s.

pidium aiix-mas var. cristafuin, Aspidiiiin falcatitm, Todea
Africana, and several others. Sometimes archegonia are pro-
duced, or they may be absent from the apogamous prothalhum,
but antheridia usually are found. When archegonia are
present they do not appear to be functional. In Pteris Cretica
(Fig. 171, A), where usually no archegonia are developed, the
cushion of tissue which ordinarily produces them is formed as
usual ; but instead of forming archegonia it grows out into a
leaf at whose base is formed the stem apex, which soon pro-
duces a second leaf. The first root arises endogenously near
the base of the primary leaf, and the young plant closely resem-
bles the sporophyte produced in the normal way. Previous to
the development of the bud there
is formed in the prothalhum it-
self a vascular bundle which is
continued into the leaf, but
is entirely absent from normal
prothallia.

The opposite state of affairs,
where the gametophyte arises di-
rectly from the sporophyte with- \,
out the intervention of spores, is
known in a number of species,
and has been especially investi-
gated by Bower (6). He found

that there were two types of F^^. i72.-Pinna from the leaf of C^;^

apospory, as he named the
phenomenon, one where the pro-
thallium was produced from a

sporangium arrested in its normal growth, and by active multi-
plication of the cells of the stalk and capsule wall forming a
flattened structure, which soon showed all the characters of a
normal prothalhum with sexual organs. In the second case the
prothallia grew out directly from the tips of the pinnae, and
there was no trace of sporangia being formed previously. The
first observations of these phenomena were made upon two
varieties, Athyrimn Ulix-focmina var. clarissima and Poly-
stichum angulare var. piikherrhmim , but since, Farlow (2) has
discovered the same phenomenon in Pteris aqiiilina. In the
latter the prothallia were always transformed sporangia. The
phenomenon of apospory was first observed by Druery (i, 2).

topteris bulbifera, with a bud ik)
at the base, X2; s, the sori (after
Atkinson).

310 MOSSES AND FERNS chap.

The production of secondary sporophytes as adventitious
buds upon the sporophyte is a regular occurrence in some
species. Asplenium bulbiferum and Cysfoptcris bulbifera are
famihar examples of such sporophytic budding. In these large
numbers of buds are formed which soon develop all the charac-
ters of the perfect sporophyte. Very early a definite apical cell is
established from which all the other parts are derived. In
Camptosorus rhizophyllus, the "walking fern" of the Eastern
United States, a single bud is formed at the tip of the slender
leaf which bends over until it takes root. From this terminal
bud another leaf grows and roots in the same way.

Classification of the Lcptosporaugiatce

The Leptosporangiatae fall into two groups, which may be
termed orders, although the tw^o families in the second order
(Hydropterides) are not closely related to each other, but each
has nearer affinities w^ith certain of the homosporous forms.

I. Homosporous Ferns with large green prothallium, usu-
ally in its early stages growing from a single apical cell ; more
commonly monoecious, but sometimes dioecious. Leaves always
circinate in vernation. Sporangia with a more or less de-
veloped annulus, either borne upon ordinary leaves or on
specially modified sporophylls. Usually, but not always, each
group of sporangia (sorus) covered by a special covering, the
indusium.

Order I. Filices. (Eufilicinese. Sadebeck (7)).

Family i. Osmundaceae.
Family 2. Gleicheniacese.
Family 3. Matoniaceae.
Family 4. Hymenophyllaceae.
Family 5. Schizcxacese.
Family 6. Cyatheaceae.
Family 7. Parkeriaceae.
Family 8. Polypodiacese.

II. Heterosporous forms, either aquatic or amphibious ; the
prothallia are always dioecious, the female prothallium with
chlorophyll and capable of more or less independent growth
when not fertilised; male prothallium always without chloro-
phyll, the vegetative part reduced to one or two cells, besides
the antheridium. Leaves either circinate (Marsiliaceae) or

IX FILICINE^ LEPTOSPORANGIAT^ 311

folded (Salviniaceae) ; sporangia without an annulus and borne
in special ''sporocarps," which are either modified branches of
ordinary leaves (Marsiliaceae) or a very highly developed
indusinm.

Order II. Hydropterides.

Family i, Marsiliaceae.

Family 2. Salviniaceae.

Order I. Filices

•

The eight families of the Filices form an evidently very
natural group, but there has been a good deal of disagreement
as to their relative positions. The Osmundacese are generally
recognised as approaching most nearly the eusporangiate Ferns,
and the Gleicheniacese come next to these. The Hymeno-
phyllacese are usually considered at the other extreme of the
series, but there are a number of reasons why this seems doubt-
ful, and I am inclined to assign them an intermediate position.
Their structure and development give evidences of their being
a specially modified group adapted to living in very damp
situations, and they probably cannot be regarded as connecting
any of the other families, but rather as a side branch which has
developed in a direction away from the type. They come near-
est the Gleicheniaceae and Osmundacese in the structure of the
sexual organs, and the sporangium shows points in common
with the former family. The sporangium, however, also re-
sembles that of the Cyatheacccne, and the strongly-developed In-
dusium is much like that of the latter. The SchizgeacCci^: also
may possibly form a side branch from the ascending serie?
which ends in the Polypodiacese.

Professor Bower (19), who does not recognize the Ophio-
glossacege as belonging to the Filicinese, divides the other hom-
osporous Ferns into three suborders, based upon the develop-
ment of the sporangia. His first suborder, "Simplices," includes
the Marattiacese, Osmundacese, Schiz?eacese, Gleicheniaceae, and
Matoniaceae. In these families all the sporangia in a sorus are
developed simultaneously, and the output of spores is rela-
tively large. The second suborder, '"Gradatse," comprises the
Hymenophyllaceae (inc. Loxsomaceae) , Cyatheaceae (inc. Dick-
sonieae — in part), and one sub-family, Dennstaedtineae, belong-
ing to the Polypodiacese. In these the sporangia arise in

312

MOSSES AND FERNS chap.

basipetal succession on the receptacle. The remaining sub-
famiHes of the Polypodiaceae constitute the suborder, ''Mixt^e,"
in which sporangia of very different ages are mixed together in
the same sorus.

The well-known Ostrich-Fern, Onoclea stnithiopteris
(Strnthioptcris Gcnnanica) illustrates very satisfactorily the
germination of the spores and the development of the gameto-
phyte and embryo in the Polypodiace^e, the typical modern
Ferns. O. scnsibilis, which may probably be better separated
•generically from Strnthioptcris, agrees closely with the latter in
the development of the gametophyte.

The large oval spores contain, besides much oil and some
starch, numerous small crowded chloroplasts. The three walls
of the spore are plainly demonstrable, especially as the brown
perinium is often thrown off by the swelling of the spore, and
the transparent exospore can then be seen, with the delicate
endospore lying close to its inner face. A large nucleus
occupies the centre of the spore. Contrary to the statements
usually made that spores containing chlorophyll quickly lose
their vitality, these will germinate after a year or more, although
not so well as those of the same season, but they normally
remain from autumn until spring before they germinate. O.
sensibilis acts in the same way, and spores of other Ferns con-
taining chlorophyll have been germinated after an equally long
period.

The spores germinate promptly, varying from two or three
days to about a week, depending upon the temperature. The
exospore is ruptured irregularly near one end, and through this
a short colourless papilla protrudes and is shut off by a trans-
verse wall (Fig. 173, B). This papilla contains little or no
chlorophyll and rapidly lengthens to form the first rhizoid,
which undergoes no further divisions. The large green cell
alone produces the prothallium. The divisions in the pro-
thallial cell vary somewhat, but in the great majority of cases a
series of transverse walls is first formed, and the young pro-
thallium (Fig. 173, C) has the form of a short filament.
Sooner or later, in normally-developed prothallia, the terminal
cell of the row becomes divided by a longitudinal wall, which
may be straight, but more frequently is oblique and followed
by another similar wall in the larger of the two cells, meeting it
so as to include a triangular cell, which is the **two-sided" apical

FILICINE^ LEPTOSPORANGIAT/E

313

Fig. 173. — Onoclea struthiopteris. A, B, Germinating spores with the perinium re-
moved, X300; C, young prothallium, Xioo; D, E, older prothallia with two-sided
apical cell (;r), X300; F, small female prothallium seen from below, X25; G,
very young prothallium with the two outer spore-coats, X300; r, primary rhizoid;
ar, archegonia; p, perinium; ex, exospore.

314

MOSSES AND FERNS chap.

cell of the next phase of the prothallium's growth. The
divisions up to this point correspond exactly with those of
Ancura or Metzgcria, and are also much the same as in Alarat-
tia, except that in Onoclea the prothallium only in very rare
cases assumes the form of a cell mass at first.

By the regularly alternating segments of the apical cell
the young prothallium soon assumes a spatulate form, which
becomes heart-shaped by the rapid growth of the outer cells of
the young segments, which grow out beyond the apical cell.
Sooner or later the single ajMcal cell is replaced by two or
more initials formed from it in the same way as in the Marat-
tiacCcT, and from this time on the growth is from a series of
marginal initials. This change is connected with the formation
of the thickened archegonial cushion, which, so far as I have
observed, does not form in Onoclea so long as the single two-
sided apical cell is present.

As the prothallium grows new rhizoids grow out from the
marginal and ventral cells and fasten the prothallium firmly
to the ground. These hairs, colourless when first formed, later
become dark brown.

In the genus Onoclea, as well as some other Polypodiaceae,
the prothallia are regularly dioecious, and only a part of them
develop the archegonial meristem. The others remain one-
layered, and are often of very irregular form, and may be
reduced to a short row of a few cells. In Athyriuni filix-
farmina these may even be reduced to a single vegetative cell
besides the root-hair, and an antheridium. Cornu ( i ) records
similar reduced prothallia in Aspidiuni fiUx-mas. All of the
''a-meristic" prothallia, as Prantl ((4), p. 499) calls them, are
males. In the majority of the Polypodiaceae these occur more
or less plentifully, and are often the result of insufficient nutri-
tion; but in Onoclea it is something more than this, as not only
the small prothallia are male, but the large ones are exclusively
female, and not hermaphrodite, as in most Ferns.

The Sex-Organs

The first antheridia appear within three or four weeks under
favourable conditions, and are formed either from marginal or
ventral cells of the prothallium. The very young antheridium
is scarcely to be distinguished from a young rhizoid. Like it,

FILICINE^ LEPTOSPORANGIAT^

315

it arises from a protrusion of the cell which is cut off by a wall,
w^iich is usually somewhat oblicjue. The papilla thus formed
enlarges and soon becomes almost hemispherical. It contains
a good deal of chlorophyll and a large central nucleus sur-
rounded by dense cytoplasm. The first wall in the young an-
theridium (Fig. 174, A) is very peculiar. It has usually the
form of a funnel, whose upper rim is in contact with the wall of

Fig. 174. — Onoclea struthiopteris. Development of the antheridium. A-C, Vertical
section, X6oo; D, two nearly ripe sperm cells; E, free spermtatozoid, X about

1200.

the antheridium cell, and whose base strikes the basal wall of
the antheridium. Sometimes this first wall does not reach to the
base, in which case it is simply more or less strongly concave,
and the basal cell cut off by it from the antheridium is discoid
instead of ring-shaped (Fig. 174, B). The second wall is
hemispherical, and is nearly concentric with the outer wall of
the antheridium. The dome-shaped central cell produces the

3i6 MOSSES AND FERNS chap.

mother cells of the spermatozoids, and has much more dense
contents than the outer cells, but all the chloroplasts remain in
the latter. A third wall now forms in the upper peripheral
cell, much like the first one in form, and cuts off a cap cell at
the top. The young antheridium at this stage consists of four
cells — a central dome-shaped one surrounded by three others,
the two lower ring-shaped, and the terminal one discoid. These
outer cells are nearly colourless and contain very little granular
contents, except the small chloroplasts, which are mainly con-
fined to the surface of the inner walls.

The divisions in the central cell are at first very regular.
The first one is always exactly vertical, and is followed by a
transverse wall in either cell which strikes it at right angles,
and next a third set of walls at right angles to both of these,
so that whether seen in cross-section or longitudinal section,
the central cells are arranged quadrant-wise. Successive bi-
partitions follow in all the cells until the number may l^e a
hundred or more, but the number is usually much less, about
thirty-two being the commonest. The regular arrangement of
the sperm cells soon becomes lost, and they form a mass of
polyhedral cells with dense granular cytoplasm, and large nuclei.
A nucleolus is visible until the last division, after which it can
no longer be distinguished ; otherwise the nuclei show no pe-
culiarities. The transformation of the nucleus into the body of
the spermatozoid proceeds here as in other Ferns that have been
examined, but I was unable to satisfy myself that so large a part
of the forward end of the spermatozoid is of cytoplasmic origin,
as Strasburger ((ii), IV, p. 115) asserts. The fully-
developed spermatozoid describes about three complete coils
within the globular sperm cell, and does not lie coiled in a
single plane, as in the Hepaticse, but in a tapering spiral (Fig.
174, D). The very numerous long cilia are attached at a
point a short distance back from the apex, and as Buchtien
((i), p. 38) showed, cover a limited zone, although hardly
so restricted as he figures.

From the investigations of Shaw (2) and Belajeff (5, 6, 7),
it is evident that the cilia arise from a blepharoplast. Belajeff
considers the blepharoplast in the Pteridophytes, as well as in
the Bryophytes, to be a centrosome; but Shaw believes that the
blepharoplast is an organ siii generis, and of quite different
nature from the centrosome.

FILICINE^ LEPTOSPORANGIATTE

317

Mottier (3) lias recently examined the structure of the sper-
matozoid in Stnithioptcris. He could detect no cytoplasmic
envelope investing the posterior coils, which seemed to be of
exclusively nuclear nature. The vesicle showed a fine cyto-
plasmic reticulum in which the larger granules were imbedded.

The separation of the sperm cells begins at about the time
the development of the spermatozoids commences. The muci-
laginous walls stain now very strongly, and in a living state
appear thick and silvery-looking. The inner layer of the
cell wall, however, remains intact, so that when the sperma-

FiG. i7S-—Onoclea struthiopteris. A, Longitudinal section of the apex of a female
prothalHum, showing the apical cell (x) and a nearly ripe archegonium, X215;
B-D, development of the archegonium; longitudinal sections, X430; h, neck canal
cell.

tozoids are ejected, they are still enclosed in a delicate cell mem-
brane, which swells up as the water is absorbed and finally
dissolves completely. The vesicle derived from the remains
of the cytoplasm is very conspicuous here, and the granular
contents usually, but not always, show the starch reaction.
The body of the free spermatozoid has the form of a flattened
band with thickened edges, which tapers to a fine point at the
anterior end, but is broader and blunter behind. The peripheral
cells of the antheridium become so much compressed by the
crowding of the sperm cells that they are scarcely perceptible.

3i8

MOSSES AND FERNS

CHAP.

but after the antheridium is burst open, the two lower ones
become so distended that they nearly fill the central cavity. The
opening is effected either by a central rupture of the cover cell,
or less commonly by a separation of this from the upper ring

cell.

The development of the archegonium is intimately connected
with the apical growth of the large female prothallium. As
soon as the single apical cell has been replaced by the marginal
initials, the divisions in the latter Ijecome very definite. Com-
parison of cross and longitudinal sections shows that these are

much like those of Marattia or,
among the Hepaticse, Dendroceros
or PclUa cpiphylla. Each initial cell
has the form of a semi-disc (Fig.
175, A), and the growth is both
from lateral segments, which mainly
go to form the wings of the pro-
thallium, and basal, or inner seg-
ments, which produce the projecting
archegonial cushion. If this begins
to form very early, it may develop a
midrib extending nearly the whole
length of the prothallium ; but usually
it does not form until relatively late.
Each basal segment of the initial cells
divides into a dorsal and ventral cell
(semi-segment), the latter the larger
of the two, and with much more
active growth. The latter alone is
concerned in the growth of the pro-
jecting cushion. Each ventral semi-
segment is first divided by a wall parallel with the primary
segment wall, and from the anterior of these cells, almost
exactly as in Notothylas, the archegonium is developed. It is
not possible to make out any definite succession of walls by
w^hich the axial cell of the archegonium is cut out, but it soon
is recognisable by the granular cytoplasm and large nucleus.
As in Marattia, the first transverse wall separates the inner cell
from the cap cell, and the inner one then divides into the basal
and the central cells. The cover cell divides into the four
primary neck cells, and the central cell arching up between these

Fig. 176. — Ripe archegonium of
O. struthiopteris in the act
of opening, X300; 0, the
egg.

IX FILICINE^ LEPTOSPORANGIAT^ 3I9

has the pointed apex cut off by a curved wall from the central
cell. The primary neck canal cell, so formed, is noticeably
smaller than that of Marattia. The neck cells, which in the
eusporangiate forms all grow alike, here show a difference, and
the two anterior rows develop faster than the posterior ones, so
that these row^s are longer and the neck is strongly bent back-
ward. In Onoclea there are usually about seven cells in each
anterior row and about two less in the posterior ones. The
neck cells are almost colourless, with distinct nuclei, and a few
small, pale chloroplasts. From the central cell is now cut off
the ventral canal cell, which is quite small, and separated from
the Qgg by a strongly concave wall. The nucleus of the neck
canal cell always divides, but no division wall is formed, and
the two nuclei lie free in the cell. The basal cell divides by
cross-walls into four, and with similar cells cut off from the
adjacent prothallial tissue constitutes the venter of the ripe
archegonium. The disintegration of the division walls of the
canals cells, and the partial deliquescence of the inner walls of
the neck cells, offer no peculiarities.

When the archegonium opens, the terminal cells diverge
widely and the upper ones are often thrown off.

The opening of the sexual organs and the entrance of the
spermatozoids may be easily seen by simply allowing the plants
to remain slightly dry for a few days until a number of sexual
organs are mature. If these are now placed upon the slide of
the microscope in a drop of water, in a few minutes the sexual
organs will open, and the spermatozoids will be seen to be
attracted to the archegonia in large numbers, and with care
some of them may be followed into the neck and down to the
central cell. The actual entrance of the spermatozoid into the
egg has been observed, but is difficult to demonstrate in the
Hving condition. Pfeffer (3) has shown that the substance
which attracts the spermatozoids in the Polypodiace?e is malic
acid, and that an artificial solution of this, of the proper
strength, will act very promptly upon the free spermatozoids of
these Ferns.

Buller ( I ) has found that in addition to malic acid and its
salts, many salts, both organic and inorganic, which occur in
the cell-sap, may exert a positive chemotactic stimulus upon the
spermatozoids of Ferns. However, none of them react so
strongly as malic acid and its salts.

320

MOSSES AND FERNS

CHAP.

Buller also showed that the starch which is usually present
in the vesicle of the spermatozoid, when it escapes from the
antheridium, disappears completely in species where the period
of activity is prolonged. Thus in Gymnograinmc Mcrtcnsii,
the swarm-period lasted about two hours, and during this time
the starch disappeared completely.

Fertilisation

Shaw (2) has made a careful study of the fertilisation in
Striithioptcris and in Onoclca. He states that before the arche-

FlG. 177. — A, Osmunda cinnamomea, section of a recently fertilised archegonium,
X450. A spermatozoid has penetrated the nucleus of the egg, and several are
in the space above the egg. B, Onoclca sensibilis. Egg fourteen hours after the
penetration of the spermatozoid, which is still recognizable within the egg nucleus,
X900. (B, after Shaw.)

gonium opens, the egg is depressed above, and the nucleus
flattened. As soon as the archegonium opens, and the dis-
organised contents of the neck cells are expelled, the egg
becomes turgid, and the depressed upper part forms the recep-
tive spot. (Fig. 177.)

The mucilaginous matter ejected from the archegonium
retards the movements of the spermatozoids, and detaches the
vesicle. As the spermatozoid penetrates the neck, it becomes
much stretched out, and forces its way through to the central
cavity of the archegonium, by a slow screw-like movement.
Having penetrated into the ventral cavity, the coils draw
together again, and the movements are much more rapid.

After a spermatozoid has entered the egg at the receptive

IX FILICWEM LBPTOSPORANGIATJE 321

spot, Shaw states that the tgg then cohapses, and suggests that
this prevents the penetration of more than one spermatozoid.
Mottier ((3) p. 139) expresses some doubt whether the
collapsed appearance of the tgg, usually found in microtome
sections, is really normal.

The spermatozoid soon penetrates into the nucleus of the
Qgg^ where for some time it remains with little change of form.
Presumably the cilia and the cytoplasmic part of the sperma-
tozoid remain in the egg-cytoplasm as they do in Cycas and
Zam ia ( Ikeno ( i ) , Webber ( i ) ) .

The body of the spermatozoid, after it penetrates the egg-
nucleus, gradually loses its homogeneous appearance, and the
nuclear reticulum becomes more and more apparent. The
spiral form becomes less evident, and the nucleus passes through
much the same changes, except in reverse order, that are seen
in its development from the nucleus of the sperm-cell. Finally
the reticulum of the male nucleus becomes indistinguishable
from that of the egg-nucleus, and the fusion is complete. Dur-
ing this fusion the egg nucleus retains its original form.
The process of fusion is slow. In one instance, sixty
hours after fertilisation, the sperm-nucleus was clearly recog-
nisable.

As soon as the egg is fertilised it develops a membrane,
and soon after undergoes its fir^t segmentation. The inner
walls of the neck cells almost immediately turn dark brown,
and the cells of the ventral part l^egin to divide actively and
form the calyptra, which here, as in the Bryophytes, is formed
from the venter alone, and is tipped with the remains of the
neck cells.

The position of the archegonium depends largely upon the
light. If both sides of the prothallium are about equally
illuminated, archegonia will develop from both sides. As soon
as an archegonium is fertilised, no new ones form, but it fre-
quently happens that a very large number prove alxirtive before
finally fertilisation is effected.

The Embryo

The first division wall in all Polypodiacese yet investigated
is vertical and nearly coincident with the axis of the arche-
gonium. This basal wall (Fig. 178, A) at once divides the
21

322

MOSSES AND FERNS

CHAP.

embryo into the anterior epibasal half and the posterior hypo-
basal. The former produces the stem and cotyledon, the
latter the primary root and foot. The early divisions are
extremely regular, and offer a marked contrast to those in the
eusporangiate embryo. The second wall is the transverse
(quadrant) wall, separating the leaf and stem in the epibasal
part, and the root and foot in the hypobasal. The next walls
are the median or octant walls, but they do not correspond

Fig. 178. — Onoclca sensibilis. A, two-celled embryo, X about 500; B, an eight-celled
embryo, longitudinal section; C, two longitudinal sections of an older embryo, X
about 250; D, E, two horizontal sections of a still older embryo; F, longitudinal
section of an advanced embryo; the cotyledon is beginning to project beyond the
other organs; co^ cotyledon; r, root; st, stem; f, foot. (All figures drawn from
sections made by Dr. W. R. Shaw.)

exactly in all the quadrants. \Miile in the cotyledon and stem
they are almost exactly median, in the root especially, the octant
wall diverges often a good deal from the median line, and the
two resulting octants are unequal in size. The following
divisions correspond for a short time in all the octants, but
soon show characteristic differences. For a short time each
octant shows a definite apical growth, the segments being cut
off by walls formed successively parallel to the three primary

IX FILICINEAL LEPTOSPORANGIATJE 2,22>

divisions in the embryo, so that each octant may be said to
have a three-sided apical cell. When the octant wall in the
root quadrant is decidedly oblique this is not always evident in
the smaller octant, and the larger one in this case at once
becomes the definitive apical cell of the primary root.

The first of these walls is usually parallel to the basal, the
second to the quadrant wall. Sometimes this order is reversed,
but never, apparently, is the first wall parallel with the octant
wall. Before the third segment is cut off from the octant, each
of the two first ones divides by a periclinal wall into an inner
and an outer cell. Each octant now consists of five cells, two
inner and three outer ones, of which one is the primary octant
cell, which still retains its original tetrahedral form. The
outer cell of each segment divides by a radial wall, but beyond
this the succession in the walls differs. Of the eight original
octants, one in each quadrant persists as the apical cell respect-
ively of cotyledon, stem, root, and foot, but in the latter it
becomes very early obliterated by the formation of a periclinal
wall and further longitudinal divisions, which is the case also
with one of the octants in the leaf and root. In the stem both
octants persist, one becoming the permanent stem apex, the
other forming the apical cell of the second leaf.

Shaw ((2), p. 280) found in one instance an embryo in
which the first wall in the hypobasal part of the embryo was
the median w^all instead of the usual transverse wall.

The Cotyledon

Of the two primary octants of the cotyledon, one very early
ceases to grow and soon becomes indistinguishable, and the
subsequent growth is due almost entirely to the activity of a
single octant. The apical cell is at first like that of the other
members, tetrahedral, but after about two sets of segments
have been cut off from it no more are usually cut off from the
side of the apical cell parallel to the basal wall, and the three-
sided cell thus passes over into a two-sided one with segments
cut off alternately right and left. By the suppression of the
growth in the sister octant, the apical cell gradually assumes a
nearly median position. By the change to the two-sided form
of the apical cell, the originally conical leaf rudiment becomes
flattened, and a little later this is followed by a dichotomy of

324

MOSSES AND FERNS

CHAP,

the growing point and the production of two apical cells like
the original one (Fig. 179, C). The division is first brought
about by a nearly central longitudinal division of the apical
cell, and on either side of this, by a curved wall running to the
outer wall of each cell, two new apical cells, separated by two
elongated central cells, result. Each of these new growing
points develops one of the lobes of the cotyledon, which undergo
one or more bipartitions before the cotyledon breaks through

Fig. 179. — Onoclca struthioptcris. A, Longitudinal section of young sporophyte still
connected with the prothallium (Pr), X6o; B, the apex of same, Xi8o; C, surface
view of the young cotyledon showing the first dichotomy; D, central region of A,
showing the primary tracheary tissue, Xi8o; E, young sporophyte \'ith nearly
full-grown cotyledon and primary root, X3; st, stem; L^, cotyledon; L^, second
leaf; F, foot; Fr, prothallium.

the prothallium. As in Marattia the growth is much stronger
upon the outer side and the leaf is strongly curved over. It
very early grows beyond the stem apex, and the embryo loses its
oval form much earlier than is the case with any of the
Eusporangiatse.

The Stem

The early segmentation of the stem apex is much the same
as in the cotyledon ; but later the divisions in the segments arc
-somewhat different, and the first wall is a radial one, instead of

^'^ riLICINEAi LIlPTOSPORANGIATAi '325

periclinal. The stem is very short at the time the young
sporophyte breaks through the prothahium, and its apex more
pointed than is afterwards the case.

The Root

At first the segmentation of the apical cell of the root is
almost exactly like that of the stem, and it is not until several
lateral segments, usually about two series of them, have been
formed that the first periclinal wall, cutting off the first cell of
the root-cap, is formed. There is a good deal of difference,
however, as to the time this occurs, and there is probal)ly some
connection between it and the different period at wdiich the
primary root breaks through the calyptra. In most Poly-
podiaceae, the root is the first of the organs to penetrate the
calyptra, but sometimes in Onoclca it is still short at the time
the cotyledon is nearly developed, and in this recalls Marattia,
where this is regularly the case. As soon as the first segment
of the root-cap is formed, the segmentation of the root Is
extremely regular, and corresponds essentially to that found in
the later roots.

The Foot

All definite divisions cease very soon in both of the foot
octants, and this part of the embryo forms a more or less pro-'
jecting hemispherical mass of cells, closely appressed to the
prothallial cells. As usual in such cases the outer cells are
large and distinct.

Shortly before the embryo breaks through the calyptra,
which takes place much earlier than in Marattia, the first traces
of the vascular bundles are seen as strands of procaml^um cells
occupying the axis of each of the primary organs, and united in
the centre, so that the four bundles together form a cross. Of
these the one going to the foot is.short, and ends blindly within
that organ, but the others continue to grow with the elongation
of the members to which they belong. The first permanent
tissue to be recognised forms, as in Marattia, a bundle of short
irregular tracheids at the junction of the young bundles (Fig.
179, D). These primary tracheids in Onoclea are scalariform,
but the pits are shorter than in the later ones. Throughout
the life of the sporophyte no vessels are formed, but only
tracheids, as in nearly all Ferns. In the cotyledon the tracheids

32(5 MOSSES AND FERNS chap.

are all spiral, and occupy the centre of the concentric bundle,
and from these growth proceeds centrifugally. The elements
of the phloem are poorly differentiated, and in this stage no
true sieve-tubes could be detected. While a definite bundle-
sheath can scarcely be made out, the limits of the bundle are
clearly defined. The venation of the cotyledon is dichotomous,
corresponding to the dichotomous branching of the lamina.

The vascular cylinder of the young stem is solid, and is
mainly composed of short and broad scalariform tracheids, but
in the centre of the bundle are some small spiral and reticulate
ones. The phloem at this stage is not well developed, and does
not show perfect sieve-tubes. The bundle sends a branch to
the second leaf, but is continued beyond the point of contact,
and develops tracheids above the point of union before the first
ones are formed in the leaf. In this early otage the bundle-
sheath is very poorly differentiated in the stem, but becomes
better marked as the plant develops.

The primary root is monarch, and the tracheary tissue com-
posed of short pointed tracheids with irregular scalariform
markings. These are surrounded by one or two layers of
narrow cells with oblique transverse septa. The calyptra is
soon penetrated by the cotyledon, which, instead of growing
straight up through the prothallium, as it does in Marattia,
breaks through upon the ventral side and then bends upward
l>etween the lobes in front (Fig. 179, E). The root l>ends
down and penetrates the earth, and very soon after, the pro-
thallium dies. The epidermis of the cotyledon produces small
glandular hairs, and that of the root numerous root-hairs.

The second leaf is directly traceable to one of the primary
stem octants, and may be either regarded as one of the primary
members of the embryo, or as the first segment of the stem.
Its development corresponds exactly to that of the cotyledon,
as it does in its fully-developed state. The second root arises
endogenously. like all the later ones, and its apical cell is formed
close to the point of union of the bundles of the leaf and stem,
and probably, as in the later roots, is derived from a cell of the
endodermis.

The new leaves arise in regular succession from the segments
of the apical cell of the stem and up to the fifth or sixth, and
possibly later the first division of the leaf is dichotomous, and
the pinnate form of the later leaves is gradually attained, as in

FILICINE^ LEPTOSPORANGIATJE

2>^7

Marattia. As the stem grows, the central stele, which at first
is solid C'protostelic"), becomes a hollow cylinder ("siphonos-
tele"), which, according to Jeffrey (3) in most Polypodiacese
shows a concentric structure, i. c, there is a central mass of
wood, with both outer and inner phloem, and an external and
internal endodermis. Sometimes, however, c. g., Davallia
stricfa, both internal endodermis and phloem are absent, and
this would seem to be the case
also in Struthiopteris (Camp-
bell (0).

A cross-section of a plant
of the latter species with three
fully-developed leaves showed
the vascular cylinder to be oval
in outline, and consisting of the
follow^ing parts. A central pith
of elongated parenchymatous
cells, surrounded by a thick ring
of short spiral and reticulate
tracheids, outside of which was
a zone of phloem, the whole
enclosed by a distinct endoder-
mis. The latter is continuous,
with the endodermis of the bun-
dles going to the leaves and
roots, and the xylem of these
also connects with that of the
stem bundle. The apex of the
stem becomes more and more
hidden by the development
of scales from the epidermis, Fig. l8o.-.4./m«/^^^«/^rfa/«»^. a. Rhizome

- . , ^ ,, , , . , . with young leaf. /. and the base of an

which hnally completely hide it older one: ^r. stem-apex. B. leaf-seg-

and form a very efficient prO-^ ment.showing venation, and sori.^y.

tection.

The petioles of the first three leaves have a single axial
vascular bundle, but in the fourth, as in all subsequent ones,
there are two. They separate very soon after leaving the stem
bundle, which is deeply cleft where they issue from it. These
bundles are typically concentric in structure, and have a well-
developed endodermis. The number of roots in the young

328

MOSSES AND FERNS

CHAP.

plant exceeds the leaves. In a plant with the fourth leaf still
unfolded, there were six fully-developed roots.

The gaps in the vascular cylinder become more and more
prominent as the sporophyte develops, and there is finally
formed the wide-meshed reticulate cylinder found in the adult
sporophyte.

In some Ferns, e. g., Ptcris aquUina, there are developed
medullary steles which arise from the inner surface of the
primitive stelar tube. (See Jeffrey (3), pp. 133, 134)-

Fig. 181. — A, Vertical longitudinal section of the apex of a rhizome of Adiantum
emargitiatuni, X25; B, the central part of the same, X180; L, a young leaf; C,
cross-section of a similar stem apex, X180; D, apex of a young leaf of Onoclea
struthioptcris, showing the apical cell {x).

The Mature Sporophyte

The Stem

The stem in most of the Polypodiace?e is either an erect or
creeping rhizome which, unlike that of the Eusporangiatae, often
branches freely. These branches are almost always formed
monopodially, and are usually of the same structure as the main
axis; but in O. struthiopteris great numbers of peculiar stolons

IX FILICINE^ LEPTOSPORANGIAT^ 329

are formed that are quite different at first in appearance from
the ordinary shoots. The main axis in this species is an
upright rhizome about 2 cm. in diameter, but appearing much
larger on account of the thick persistent leaf-bases which cover
it. The stolons arise from the bases of these leaves, apparently
as adventitious buds. They may remain dormant for a long
time, as very many more of the very small ones are found than
those that are fully developed. They finally bend upward,
and the scattered scale-like leaves give place to the perfect green
ones. The main rhizome is occupied by a central cylinder com-
posed of a netw^ork of anastomosing bundles. Inside of this
cylinder is a medulla made up of large parenchyma cells, and
communicating with the cortex by means of the foliar gaps, or
spaces between the bundles.

Fig. 181, A show^s a longitudinal section of the apex of a
stem of Adiantiun emarginatmn, which shows the typical ap-
pearance in the Polypodiaceae. The apex of the stem forms a
slight cone, whose centre is occupied by the large initial cell,
which is deeper than broad. In cross-section it shows much
the same form. Divisions occur, evidently, only at compara-
tively long intervals, and each segment presumably gives rise to
a leaf. The first division in each segment is longitudinal and
perpendicular to its broad faces. Each of the six semi-segments
is then divided into an inner and an outer cell, and the latter
again by a longitudinal wall parallel to its inner and outer faces,
so that each original segment is divided into two inner cells
and four outer ones. From the inner cells the pith and vascular
bundles arise, from the outer ones the cortex and epidermis,
but after the first divisions there is great irregularity in the
succession of the cells. The young vascular bundles can be
traced nearly to the apex, and first appear as bundles of pro-
cambium cells, wdiich lower down unite and are joined by others
from the leaves and roots.

In O. struthiopteris characteristic air-chambers are formed
in the young medulla at an early period. At certain points
the cells become longer and their contents more transparent.
These cells divide less rapidly than the surrounding tissue, and
large intercellular spaces are formed. The loose cells about
ihese form masses of trichomes, either hairs or scales, w^hich
later dry up and leave a large empty space, which may or may
not communicate with the exterior through the foliar gaps.

330

MOSSES AND FERNS

CHAP.

In Onoclca struthioptcris, as in most leptosporangiate Ferns,
the outer cortical cells become changed into sclerenchyma.
The sclerenchyma forms several hypodermal layers, distinctly
separated from the inner cortical parenchyma. These scler-
enchyma cells are much elongated ; their lateral walls are some-
what uneven, and in their younger stages swell up more
strongly under the action of potassic hydrate than do the cortical
cells. Their walls become thick, are first pale yellow, and later
a dark reddish brown. The walls are very markedly striate,
and the central lamella distinct. Deep pits extend down to the
latter.

The bundles in the stems of the Polypodiace?e are very
uniform in structure. They are usually elliptical in section,
and the first tracheary tissue formed is a strand of small spiral
or reticulate tracheids at the foci of the bundle. From there
the formation of the very large scalariform ones, so character-
istic of the leptosporangiate Ferns, proceeds towards the centre
of the bundle, where the last-formed ones are situated. The
young tracheids have thin walls and abundant protoplasm, but
as the wall thickens, the contents gradually disappear, and

Fig. 182. — Polypodium falcatum; A, Transverse section of the rhizome, X6; B, a sin-
gle vascular bundle, X175; ^"* endodermis.

finally no living protoplasm remains in them. Faint elongated
transverse pits become evident, and the spaces between these
rapidly thicken at the expense of the cell contents until all the
protoplasm is used up. The thickened bars between the pits
give the characteristic ladder-like appearance to the older

FILICINEJE LEPTOSPORANCIAT^

331

tracheid (Fig. 184, B). In cross-section these bars are nearly
rhomboidal, and give the famihar beaded appearance to sections
of the tracheid wall.

Sieve-tubes of very characteristic form are found in the
bundles of all the Polypodiaceae. In O. striithioptcris they
occupy an irregular area at each end of the bundle. Their
differentiation begins shortly after that of the large scalariform
tracheids, and in some respects resembles it. The procambium
cells from which they arise are uniform in diameter, and have
squarer ends than the young tracheids. Their contents are
more colourless and finely granular than those of the tracheids,
and the nucleus not so evident. The formation of the sieve-

u III

Fig. iS3.—Woodu.'ardia radicans. A, Part of a transverse section of a vascular bundle
of the rhizome, X 400 (about); B, transverse section of a root, X70; t, tracheids;
s, sieve-tubes; en, endodermis.

plates begins by transverse thickened bars on the lateral \valls,
less regular than in the tracheids,, and the bars more or less
anastomosing so as to enclose thin areas, the sieve-plates (Fig.
184, D, E). These occur all over the lateral walls, as well as
the transverse ones. While it.could not be positively shown, it
is extremely probable that the pores, afterwards formed, pene-
trate completely the thin membrane of the sieve-plates, and
throw the adjacent sieve-tul3€S into communication.

While it is usually supposed that there are no nuclei in the
adult sieve-tubes, in several instances, evidences of the presence
of a number of small nuclei were met with. A further inves-
tigation of this point is desirable.

With the tracheary tissue is mingled more or less wood-

332

MOSSES AND FERNS

CHAP.

parenchyma, and in the phloem the sieve-tubes are accompanied
by bast parenchyma.

Outside the phloem is a layer of cells, which may be double
in some places, and which usually contain a good deal of starch.
According to Strasburger ( (ii). Vol. 3, p. 446) these cells do
not constitute a true pericycle, l^ut belong to the cortex. They
are sister-cells of the endodermis, which is thus, not the inner-
most cortical laver, but the next but one. The endodermal cells

show the characteristic thickenings on their radial walls.

par

Fig. 184. — Woodwardia radicans. A, Tracheids, t, and wood-parenchyma, par., irow
the rhizome, X225 (about); B, longitudinal section of two tracheids, more strong-
ly magnified; C, section of the wall between two tracheids; D-F, sieve tubes.

The Leaf

While the leaf in a few of the Leptosporangiatse is simple,
in much the larger number it is compound, either dichotomously
branched {Adiantuin pcdatuin) or more commonly pinnately
divided. Owing to the great irregularity of the divisions and
slow formation of new segments in the stem apex, it is exceed-
ingly difficult to determine positively whether each segment of
the stem apex produces a leaf, but this seems probable. The
leaf appears as a blunt conical emergence, whose apex is occu-
pied by a single large apical cell, which in nearly all forms
examined is wedge-shaped and forms two rows of segments.
As the leaf grows it assumes the form of a flattened cone with a

IX FILICINE^ LEPTOSPORANGIAT^ 333

broad base, more convex on the outer side, and very soon show-
ing the circinate vernation. The petiole grows much more rap-
idly than the lamina, which remains small until the close of the
season before which it unfolds. In most species of colder cli-
mates the development of the leaves is very slow, and may oc-
cupy three or four years. The last stage of growth consists
merely in an expansion of the leaf, with comparatively little cell
division. This latter phase of growth often goes on with great
rapidity, in strong contrast to the excessively slow growth
during the early stages.

The first wall in the young segment of tlie apical cell
divides it into an inner and an outer cell, and the latter then
divides into two by a longitudinal wall, and each of the latter
into two more by a transverse wall. Of these five cells, the
inner ones, in the lamina of the leaf, produce the rachis, the
outer ones the lamina itself. The outer cells of the segments
form the pinnae. Soon after the separation into lamina and
petiole, the development of pinnae begins in those Ferns which,
like 0. stnithioptcris, have pinnate leaves (Fig. i8i, D). Their
formation is strictly monopodial, and begins by an increase in
growth in the outer cells of the young segment, which thus
forms a lobe. The marginal cells divide rapidly by longitudinal
walls, so that at first the young pinna does not grow from a
single apical cell, but sometimes two of the division walls inter-
sect and an apical cell is formed. Whether this always happens
could not be absolutely determined. As each pinna corresponds
to a segment of the apical cell of the leaf, it follows that they
alternate with each other on opposite sides of the rachis.
Where they grow from an apical cell, the divisions follow
those in the apex of the leaf. From the inner cells of the
segments the rachis of the pinna is developed. The midrib of
each lobe of the pinna bears the same relation to it that the
rachis does to the pinna itself. The secondary veins arise in
acropetal succession, and at first form a strand of procambium
reaching from the midril^ to the margin. Where dichotomy of
the veins occurs, as it so frequently does in their ends, this is
connected with a dichotomy of the marginal group of meriste-
matic cells (Sadebeck (6), p. 270). Each marginal cell, like
the segment of the apical cell of the leaf, divides into an inner
and an outer cell. The latter then divides longitudinally, and
the dichotomy is thus inaugurated. These secondary marginal

334

MOSSES AND FERNS

CHAP.

cells now repeat the same divisions, and the two diverging rows
of inner cells form the beginning of the young veins.

Except the smallest veins, which are collateral, the bundles
are typically concentric, and differ only in minor particulars
from those of the stem. The ground tissue of the petiole shows
much the same structure as that of the rhizome in most Ferns,
and usually develops several layers of hypodermal sclerenchyma.
In the lamina, the cells of the ground tissue, or mesophyll, as the
leaf expands, separate and form large intercellular spaces be-

FiG. 185. — Adiatitum emarginatum. Development of the stomata, X525; v, accessory

cell; st, stoma mother cell.

tween them. The cells are in many places connected by pro-
longations or protrusions of the wall. On the upper side, in
cases where no stomata are developed, an imperfect palisade
parenchyma may form, but in none of the forms examined by
me was it nearly so distinct as in Angioptcris. The fully-de-
veloped epidermal cells are very sinuous in outline, and always
contain numerous chloroplasts.

In Onoclca strnthioptcris stomata are developed only upon
the lower side of the lamina, but sometimes these also are found

IX FILICINE^ LEPTOSPORANGIAT^ 335

Upon the upper surface. Usually, but not always, the devel-
opment of the young stoma is preceded by the formation of a
preliminary cell (Fig. 185, v), horse-shoe shaped, and cut-
ting off a small cell from one corner of an epidermal cell. A
similar wall forms within this small cell, parallel to the first
one (Fig. 185, B, st) , and the cell thus separated is the stoma
mother cell. A longitudinal wall next divides this, and then
splits in the middle to form the pore of the stoma (Fig. 185,
C). This wdien complete is exactly in structure like those of
other vascular plants, and like them communicates with the air-
spaces of the mesophyll. The accessory cell enlarges very
much with the expansion of the leaf, and its walls have the same
sinuous outline that the other epidermal cells exhibit. A curi-
ous variation of the ordinary form is seen in Ancimia (De
Bary (3), p. 42), where the mother cell of the stoma is cut out
by a perfectly circular wall, very much like the funnel-shaped
one in the antheridium, and the stoma is apparently free in
the centre of an epidermal cell. It seems that this also occurs
In Poly podium lingua (De Bary, 1. c).

Most of the Leptosporangiatse are characterised by numer-
ous epidermal outgrowths, either hairs or scales. These are
especially abundant upon the younger parts, and are largely
protective. The hairs are either simple or glandular ones. In
the latter case the gland is usually a terminal, pear-shaped cell,
which secretes mucilaginous matter, or less frequently (Onoclea
struthiopteris) this secretion may be resinous. In the common
Californian ''gold-back" Fern, Gynmo gramme triangularis, the
yellow powder upon the back of the leaf is a waxy secretion,
derived from epidermal hairs. Of similar nature are the large
chaffy scales (palese) which occur in such numbers upon the
bases of the petioles of so many Ferns. This development of
hairs, however, is most marked in the large tree-Ferns, Dick-
sonia, Cihotium, etc., where the young leaves are completely
buried in a thick mass of brown w^ool-like hairs, which are
sometimes utilised as a substitute for wool in stuffing mat-
tresses, etc.

The Root

The roots arise in large numbers in most Ferns, and appar-
ently bear no definite relation to the leaves. The primary ones
are first visible very near the apex of the stem (Fig. 181, A, r),

336

AIOSSES AND FERNS

CHAP.

and Van Tieghem (5), who has made a very exhaustive study
of the subject, states that they ahvays arise from an endodermal
cell. This divides into a basal cell and a terminal one, and by
the former the young root is directly connected with the xylem
of the stem bundle. In the outer cell the three walls defining
the pyramidal apical cell now arise, and the latter at once be-
gins its characteristic divisions.

The segmentation in the apex of the roots of the Lepto-

sporangiatae is exceedingly regular.
Corres])onding to each set of lateral
segments an outer segment forms
as well. Van Tieghem does not
apparently recognise the root-cap
as distinct from the epidermis, but
all other observers consider the root-
cap as a distinct structure. The
first division wall in the lateral seg-
ments is the sextant wall, which is
perpendicular to the broad faces of
the segment and curves somewhat
so as to strike one of the lateral
walls a little above the base, and
thus makes the two sextant cells of
unequal size (Fig. 188, C). The
next wall is transverse and sepa-
rates an inner from an outer cell,
and with this divides the plerome or
stele from the cortex. After this
in the outer of the primary cells
there is a separation of an outer
from an inner cell, the former giving rise either directly or l)y a
subsequent division to a single layer of cells upon the outside
of the root, which is usually regarded as the epidermis, and the
inner cells from the cortex. The inner layer of the cortex,
which can be traced back almost to the summit, is the endo-
dermis.

According to Strasburger (10) in Ptcris Crctica the cap

cells divide only by perpendicular walls, and the older layers of

the cap remain but one cell in thickness. Van Tieghem states

((5)' P- 53-) ^"^^ I ^^^""'^ verified this in Adiantum cmargina-

tuui and Polypodium falcatitm, that with the exception of the

Fig. 186. — Scale from the stipe of
Cystoptcris fragilis, X^S-

FILICINE^ LEPTOSPORANGIATJE

337

first- formed cap cell (or "epidermal segment," to use his termin-
ology), there is, in the central part, always a doubling of the
cells by periclinal walls, so that each layer of the older root-cap
is normally double, except sometimes at the extreme edge.

There is very little displacement of the cells for a long time,
and cross-sections of the root, made some distance below the
summit, still show the limits of the original sextant walls, which
form six radiating lines with periclinal walls arranged with
great regularity. In the centre the divisions proceed with great
rapidity, and the plerome soon shows the elongated narrow pro-
cambium cells. In the centre are four much larger cells, which
develop later into tracheids, and three of these can be traced
back to the central cells
of the three larger sex-

tants (Fig. 1 88, D) ; the
fourth arises from the in-
ner cell of one of the smal-
ler ones. This central
group of cells marks the
position of the plate of
tracheary tissue, found
later in the root. By this
time the parts of the com-
plete root are all indicated.
The bundle is bounded
externally by the endo-
dermis, w^hose cells are
much elongated trans-
versely, and clearly dis-
tinguishable from the peri-
cambium (pericycle), which consists of one or two rows of
cells. Inside this is the mass of procambium cells, the large
tracheids of the central part of the xylem being very evident
(Fig. 1 88, E). The masses of procambial cells on either side
of this central line of cells constitute the young phloem.

The primary tracheids (protoxylem) arise simultaneously
at the foci of the section, and consist of a single line of narrow
pointed tracheids, with fine spiral markings, very closely set at
first, but later pulled apart somewhat with the increase in length
of the root. These are formed a long time before any other
permanent tissue elements can be distinguished. Around these

Fig. 187. — Pteris cretica. Origin of lateral
rootlet from the endodermis of the root; en,
endodermis of the main root; x, apical cell
of the rootlet; p, "digestive pouch." (After
Van Tieghem.)

338

MOSSES AND FERNS

CHAP.

primary tracheids are formed a group of similar ones, and from
here the formation proceeds towards the central group of large
tracheids, which are the last to have their walls thickened and
lignified. The large secondary tracheids are scalariform, like
those of the stem. The cells of the pericycle remain nearly
unchanged, but in the two phloem masses, according to Poir-
ault (i) sieve-tubes are always present. These tubes are of
two types, those with horizontal transverse walls, and those
with inclined ones. The perforations in the sieve-plates were

Fig. i88. — Adiantum emarginatum. A, Longitudinal; B-E, a series of transverse sec-
tions of the root, X200; x, apical cell; s-s, sextant walls; en, endodermis.

demonstrated, and lateral perforations, either isolated or in
groups, also occur. His statement that the sieve-tubes have no
nuclei requires further proof. The walls of the sieve-tubes are
of cellulose, but in the sieve-plates callus is found. The rest of
the phloem is composed of conducting cells, with thin walls and
oblique septa. The endodermis often becomes dark-coloured
and its walls lignified, and when the root dries the vascular
cylinder becomes separated from the ground tissue by the trans-
verse splitting of the endodermal cells.

IX FILICINEJE LEPTOSPORANGIAT^ 339

The secondary roots arise in regular succession in two lines,
corresponding to the ends of the xylem plate in the diarch
bundle. They themselves generally branch further, and thus
very extensive root systems are formed. The origin of the
lateral roots of the Ferns has been exhaustively studied by
Lachmann (7), but their position seems to be of very little im-
portance systematically, and except in a few cases like
Osmunda, where two roots regularly arise from each leaf, there
is little relation between roots and leaves. In creeping rhi-
zomes they arise either mainly from the ventral side or from
all parts indifferently. As yet the only forms in which com-
plete absence of roots is known among the Leptosporangiatse
are Salvinia, species of Trichomancs, and Stromatoptcris
(Poirault (2), p. 147), one of the Gleicheniacese. In all of
these, however, there are substitutes either in the form of modi-
fied leaves {Salvinia) or root-like rhizomes.

The formation of buds from the roots, such as occur in
Ophioglossum, has been also observed in some Leptosporan-
giatse. This was first discovered by Sachs in Platyccriuin
Wallichii, and later described by Rostowzew ( i ) ; and Lach-
mann (7) also describes it in Anisogoniuui Scnnainporcnse.
In all these cases the apex of the root appears to become trans-
formed directly into the apex of the bud (Fig. 171, B).

The Sporangium

The development of the sporangium of all the Leptosporan-
giatse is much the same, but the position of the sporangia, and
the character of the indusium when present, vary much, and
will be discussed later as the different families are treated sep-
arately.

In the Polypodiaceae the sporangia, as is well known, arise
usually in groups (sori) upon the backs of leaves that differ
but little from the ordinary ones. Sometimes, however, e. g.,
Onoclea, they are very different, the sporangia being produced
in great numbers, and the lamina of the leaf is much contracted.
One of the simplest cases is seen in Polypodiuni. Here the
sporangia develop late upon ordinary leaves, and form scat-
tered round sori, bearing, however, a definite relation to the
veins — in this case forming above the free end of one of the

340

MOSSES AND FERNS

CHAP,

small veins. AMiere there are special sporophylls, the develop-
ment of the sporangia begins before the leaves begin to unfold.
In Poly podium (Fig. 190) the first evidence of the forma-
tion of sporangia is a series of minute depressions upon the
lower side of the leaf, much as occurs in Angioptcris. The
bottom of this depression is occupied by a low elevation, the
placenta, and upon this the sporangia form in an analogous

St.

Fig, 189. — Polypodium falcatum. A, Cross-section of a sterile leaf, cutting across one
of the smaller veins, X260; st, section of a stoma; B, similar section of a sporo-
phyll, showing the position of the sorus above the vein, X85.

way, but are not all developed at the same time, so that a single
sorus may contain nearly all stages of development. The spo-
rangium here can be readily traced back to a single epidermal
cell.

The sporangial cell protrudes until it is nearly hemispher-
ical, when it is cut off by a wall level with the surface of the

FILICINE^ LEPTOSPORANGIATAL

341

placenta. The basal cell takes no further part in the develop-
ment of the sporangium, and after a time becomes indistin-
guishable. The outer cell now divides by a wall, occasionally
transverse, but much more commonly strongly inclined (Fig.
190, A), and striking the basal wall. This is now followed by
two others, also inclined, and meeting so as to enclose a pyram-
idal apical cell, from which a varying number of lateral seg-
ments are cut off. These form three rows, corresponding to
the three rows of cells found in the stalk, which is not sharply
separated from the capsule, as stated by Goebel ( ( 10), p. 218),
and formed from the lower of two ])rimary cells, but is merged

Fig. igo.—Polypodium falcatum. Development of the sporangium. A-E, from living
specimens; F, G, microtome sections; A, B, C, optical sections; D, E, the same
■ sporangium, showing respectively the surface cells and central optical section; t, t,
tapetum. A-E, X400; F, G, X200.

gradually into the capsule, and owes its three-rowed form to a
primary and not a secondary division. The upper part of the
young sporangium enlarges, so that it becomes pear-shaped
(Fig. 190, B), and a periclinal wall is then formed in the apical
cell. The cells of the stalk undergo no longitudinal divisions,
;=and it remains permanently composed of three rows,
rrrr!; Kiindig (i) first called attention to the real state of affairs,
;and since, C. Miiller (2) has investigated the matter further.

342 MOSSES AND FERNS chap.

The central tetrahedral cell of the young sporangium (arche-
sporium) has cut off from it, by periclinal walls, the primary
tapetal cells (/), and in the meantime the wall of the capsule
forms repeated radial divisions but no periclinal ones, and, un-
like that of the eusporangiate Ferns, always remains single-
layered. A surface view of the sporangium at this stage shows
the last-formed lateral segment to still retain its triangular
form, and the cell divisions in it are very regular. After two
or three transverse divisions, a median vertical wall follows,
and in each of the resulting cells a transverse w^all. Of the two
upper cells, one, according to Miiller, remains undivided, the
other divides again by a vertical wall, and the inner of the two
cells thus formed by further transverse divisions forms the
stomium or mouth of the sporangium.

The cells of the young sporangium contain but little gran-
ular contents, and the divisions are very evident. As soon
as the archesporium is formed its contents begin to assume a
more granular appearance, and become more highly refractive
than those of the surrounding cells. The contrast between the
archesporial cells and those of the wall increases as the sporan-
gium grows older.

The first division in the central cell begins soon after the
separation of the primary tapetal cells. The direction of this
first wall is usually transverse, but may be more or less inclined,
or even vertical. In each of these cells a wall is formed at
right angles to the first-formed, and the quadrant cells are
again divided into equal octants. Each of these eight cells
divides once more (Fig. 190, G), and the sixteen spore mother
cells, found in most Ferns, are complete. In Onoclea struthi-
opteris I found twelve as the ordinary number, but at what
point the division is suppressed was not made out. During the
division of the central cells the tapetal cells also divide, first by
radial walls only, but later by one set of periclinal walls. This
doubling of the tapetum, while it occurs in the majority of
PolypodiacCcX, does not seem to l3e universal (Goebel (10),
p. 218). The cells of both sporogenous cells and tapetum have
dense granular cytoplasm, and large nuclei. Soon after the
divisions in the sporogenous complex are completed, the walls
of the tapetal cells become broken down, and their contents
dispersed through the large central cavity. The sporangium
continues to enlarge rapidly after this, and the spore mother

TX FILICINEM LEPTOSPORANGIAT^ 343

cells, still united, float in a large cavity, which in the living
sporangium seems to be filled with a structureless mucilaginous
fluid, but wdien fixed and stained is seen to contain the un-
changed nuclei of the tapetum, as well as its cytoplasmic con-
tents. Gradually the connection between the sporogenous cells
is lost, and the isolated cells, each surrounded by a very delicate
membrane, float in the large central cavity. Here they divide
into four cells, as usual, and the division may be simultaneous,
resulting in tetrahedral spores, or successive (Onoclea), in
which case bilateral spores are formed. Strasburger ((12),
p. 239) states that during the division of the spores in Osmnnda
there is a reduction of the chromosomes to one-half their orig-
inal number, but in a later paper (14) he reports that although
there is a reduction in the number of chromosomes, the ratio of
twelve to twenty-four, which was first given, is not absolutely
constant. Stained microtome sections of sporangia during the
formation of the spores show that the spore mother cells, and
afterwards the spores themselves, are embedded in a granular
matter, evidently the product of the disorganised tapetum, and
that the nuclei of the latter are collected about them, evidently
intimately associated with the growth of the young spores, and
in the later stages, wath the formation of the perinium. The
latter is rarely smooth, but shows spines, ridges, and folds of
characteristic form in different species.

When chlorophyll is present in the ripe spore it only arises
at a late period. In Onoclea striithiopteris, about the time that
the perinium begins to form, numerous small colourless gran-
ules appear near the nucleus, and with the ripening of the spore
these increase rapidly in size and number, and an examination
shows that the increase in number is the result of division.
These are young plastids, and as they enlarge, chlorophyll is
formed in them and they become very much crowded, so that
the green colour of the ripe spore is very pronounced.

The further history of the sporangium wall is somewhat
complicated. The stomium, as we have seen, arises from a
special cell of the last-formed lateral segment. The segment
on the opposite side (next older but one) shows a quite similar
arrangement of cells, and, according to Miiller, the cell corre-
sponding to the stomium by two transverse walls forms the
first segment of the annulus. The cells immediately below also
divide similarly, and give rise to a second section. The rest of

344

MOSSES AND FERNS

CHAP.

the annulus arises from the upper or cap segment of the spo-
rangium wall, and extends from the stomium over the top of
the sporangium, and joins the part of the annulus upon the
other side. The walls of all the cells are at first alike, but those
of the annulus begin to thicken, this being confined to their
inner and radial walls, the outer walls remaining thin. In most
species the cells of the annulus are the same for the whole ex-
tent, but in Polypocliimi falcatum (Fig. 191), which is figured
here, the cells of the annulus immediately above the stomium

are larger and thinner-
T walled. The stomium
cells are more extended
laterally than the other
cells of the annulus, and
between them the spo-
rangium opens by a wide
horizontal cleft

Atkinson ((3), p. 68)
describes the process
o| thus for the Polypodi-
ace?e. "While the open-
ing of the stomium be-
tween the lip cells is aid-
ed by their peculiar form,
it seems possible that at
maturity the line of un-
ion is less firm than be-
tween the other cells.
The fissure once started
proceeds across the lat-
eral walls of the sporan-
g i u m , usually in a
straight line, thus split-
ting in half the cells of the middle row, their frailty favouring
this. The drying of the annulus brings about the unequal ten-
sion of its cell walls. During this process it slowly straight-
ens, carrying l)etween the distal portion of the lateral walls
of the sporangium, which remain attached to the free extrem-
ity, the greater part of the spores. When straight, it continues
to evert, and this usually proceeds until the two ends of the
annulus nearly or quite meet, when with a sudden snap it

Fig. 191. — Surface view of a nearly ripe sporan-
gium of Folypodium falcatum, X175; -^^
stomium; r, annulus.

IX FILICINEAi LEPTOSPORANGIATJE 345

throws the spores violently away and returns to nearly its
normal position."

Paraphyses, in the form of pointed hairs, often with a
glandular terminal cell, sometimes occur with the sporangia.
These in some Ferns, e. g., Aspidium filix-mas, are direct
outgrowths of the sporangium itself.

CHAPTER X

THE HOMOSPOROUS LEPTOSPORANGIAT^ (FILICES)
FaM. I. OSMUNDACE^ {Dicls (j))

The Osmundace?e, which in many respects form a transition
from the eusporangiate to the leptosporangiate FiHcineae, are
represented by two genera, Todca (inc. Lcptoptcris), with four
species, mostly confined to Australasia, one species only
being found in South Africa; Osinunda, with six or seven
species, belonging mainly to the temperate and warm temper-
ate regions of the northern hemisphere. The widely distrib-
uted species O. regalis is found also in South Africa, but other-
wise they belong exclusively to the northern hemisphere. Os-
iiiiDida has the large sporangia borne on very much modified
sporophylls, which recall strongly those of Botrychium or Hcl-
ininthostachys; Todea, while its sporangia are like those of
Osniiinda, has them borne upon the backs of ordinary leaves.

The Gamctophyte

The development of the gametophyte is completely known
in Osmunda (Kny (5); Campbell (12)) and somewhat less
perfectly in Todea (Luerssen (3)), which does not, however,
seem to differ essentially from Osinunda. In the latter there
is considerable difference in the species examined. In all of
them the spores contain chlorophyll at maturity, and quickly
lose their power of germination. Sown as soon as ripe, they
germinate very promptly, and the first division of the spore
often takes place within twenty-four hours. The early stages
show great variation, even in the same species, and these seem
to be often quite independent of external conditions. The un-

346

THE HOMOSPOROUS LEPTOSPORANGIAT^

347

germinated spore has an exceedingly delicate endospore, which
is difficult to demonstrate, but after the exospore bursts along
the three ventral ridges, and the endospore is exposed, it be-
comes very evident.

The first division takes place after the spore has elongated
slightly, and is usually transverse, separating the small rhizoid

sp D

Fig. 191. — Osmunda Claytoniana. A, Ungerminated spore; i, ventral surface; 2,
optical section, X550; B, germinating spores, X275; r, primary rhizoid; C-E, older
stages, X275; sp, spore membrane; x, apical cell.

from the large prothallial cell (Fig. 191, B). The young rhi-
zoid contains chlorophyll, but not so much as the larger cell.
As germination proceeds the chloroplasts separate and increase
in size. They are often arranged in lines extending from the
large nucleus to the periphery of the cell. As a general thing,

348

MOSSES AND FERNS

CHAP.

the growth of the prothahium is exactly opposite to that of
the first rhizoid (bi-polar germination), and Kny ((5), p. 12)
lays a good deal of stress upon this, as distinguishing Osmiinda
from the Polypodiacere ; but it is not at all uncommon for 0.
Claytoniana, especially, to have the axis of growth of the rhi-
zoid almost or quite at right angles to that of the prothallium,
exactly as in the Polypodiace?e. Where the germination is
truly bi-polar the exospore is pushed up with the growing pro-
thallium, and appears like a cap at its apex, but if the rhizoid is
lateral, the exospore remains at the base.

In 0. Clavfojiiaua there are usually several transverse walls

Fig. 192. — Osmunda cinnamomea. A, Young prothallia; B, an older prothallium, X260.

formed before any longitudinal ones, but in O. cinnamomea
and O. rcgalis it is quite common to have the first transverse
wall followed by a longitudinal wall in each cell, so that the
four primary cells are arranged quadrant-wise (Fig. 192, A,
c). Rarely the first wall in the prothallial cell is longitudinal,
as is often the case in Equisetum, and sometimes the first divi-
sions are in three planes, so that a cell mass is formed at once,
as so often occurs in the Marattiacese. Where a filamentous
protonema is formed, a two-sided apical cell is soon established
in exactly the same way as in Onoclca. AMiere the four quad-
rant cells are formed, one of the terminal ones becomes at once
the apical cell.

X THE HOMOSFOROUS LEPTOSPORANGIAT^ 349

As soon as the apical cell is established, growth proceeds
as in Onoclca, and a heart-shaped prothallium is formed. One
difference, however, may be noted. Each segment cut off from
the apical cell divides first by a transverse wall into an inner
and an outer cell, but the inner cell from the first undergoes
divisions by horizontal walls, so that a central midrib is formed,
very much as in Met::geria, and the prothallium becomes more
elongated than is common in the PolypodiacCce. The single
two-sided apical cell persists for a long time, but is finally
replaced either by a single cell, much like that of PcUia
cpiphylla, or more commonly by a series of marginal cells, as
in the Marattiaceae or Polypodiaceas. The subsequent growth
of the prothallium is the same as in those forms, but no definite
relation could be made out between the archegonia and the
segments of the initial cells. Among the Hepaticae Dendro-
ceros offers almost an exact analogy in the form of the apical
cells and the divisions of the segments.

According to Luerssen (3), in Todea a distinct apical cell
is often wanting, and the growth throughout is due to the
activity of several similar initials. His figures, however,
hardly bear out his statement, and further information is de-
sirable on this point.

As the prothallia grow older the midrib becomes conspicu-
ous, and projects strongly from the ventral surface. In O.
cinnarnomca and O. rcgalis even at maturity it is very little
broader where the archegonia are formed; but in 0. Claytoni-
ana it forms a cushion in front, much like that of Marattia or
the Polypodiacese, and in this respect, as wd\ as in the form of
the apical cells, seems to approach the latter. In this species
the prothallium is lighter coloured, and the rhizoids not so
dark, while in its dark green colour and fleshy texture 0. ci}i-
iiamornea recalls Anthoccros Iccvis or Marattia.

Where a cell mass is formed at first, this condition is tem-
porary, and an apical cell is established which gives rise to the
ordinary flat prothallium. The small male prothallia, which are
produced in large numbers, exhibit various irregularities and
quite commonly do not show any definite apical growtli, and in
O. Claytoniana especially often branch irregularly, or in some
cases tiiere is a true dichotomy (Fig. 193, A.) Slender fila-
mentous prothallia are especially common in this species (Fig.
194, C), and recall somewhat those of some species of Trich-
omanes.

350

MOSSES AND FERNS

CHAP.

The prothallia of the Osmundacese often form adventitious
buds, much hke those of the ^larattiacese. These secondary
prothahia (Fig. 194, B) generally arise from the margin, but
may be produced from the ventral surface. An apical cell is
usually early established, and the subsequent growth is closely
like that of the primary one.

Fig. 193. — A, Apex of a young prothallium of O. Claytoniana, with two similar initials,
X, X, X560; B, longitudinal section of an advanced prothallium of O. cinnamomea,
X260; C, horizontal section of a similar one, showing two initials, X260.

The prothallia are long lived if they remain unfertilised,
and Goebel ( (16), p. 199) states that in O. regalis they may
reach a length of four centimetres. He also records a genuine
dichotomy of the older prothallia of this species.

The Anthcridlum

Under favourable circumstances the first antheridia appear
after about a month in O. Claytoniana, and continue to form

THE HOMOSPOROUS LEPTOSPORANGIATM

351

for a year or more. In O. cinnamomea they first appeared
about two weeks later. While they are almost always present
upon the large female prothallia/ numerous exclusively male
plants are always met with. These latter are usually irregular
in form, and even filamentous, especially wdien crowded. Upon
the latter the antheridia are either terminal or marginal ; in the
flattened prothallia they occur mainly upon the margin and

Fig. 194. — A, ProthalHum of O. Claytoniana, about two months old, X about 30; B,
base of an older prothallium of the same species with a secondary prothallium
ipr-) growing from it, X8o; (^, antheridia; C, small branching male prothallium
of the same species, X7S.

lower surface of the wings. ^The development corresponds
closely in all forms that have been examined, and differs con-
siderably from that of the Polypodiacese.

The mother cell is cut off as usual but the second wall is
not funnel-shaped, but plane and inclined, so that it strikes the
basal cell. In the larger of the two cells thus formed a vary-

1 Luerssen (/. c. p. 449) states that they are often absent from very vig-
orous prothallia. i

352

MOSSES AND FERNS

CHAP.

ing number of divisions occur, cutting off a series of lateral
segments, much after the fashion of a three-sided apical cell.
The segments thus cut off form the basal part of the anther-
idium, and when the number is large a pedicel may be formed.
When the full number of basal segments is complete, a dome-
shaped wall arises in the apical cell, as in the Polypodiaceae, and
the central cell has much the same form (Fig. 195, A). This
has no chlorophyll, and as usual the large distinct nucleus is
embedded in dense highly refractive cytoplasm. There are

Fig. 195. — A-D, Development of the antheridium of O. cinnamomea, in longitudinal
section, X425; E, F, G, three surface views of ripe antheridia of O. Clay-
toniana; E, from above, the others from the sifle; o, opercular cell, X425.

next developed in the outer dome-shaped cell two or three w^alls,
running more or less obliquely over the apex; either at the top
or at one side the last-formed wall encloses a small cell, which
is thrown off when the antheridium opens (Fig. 195, o). This
opercular cell, both in form and position, recalls strongly that
found in the T^Iarattiaceae.

The divisions in the central cell correspond closely to those
in Onoclca, but the number of sperm cells is larger, being usu-
ally 100 or more. The development is also the same, and will
not be entered into here.^ After the final division of the sperm
cells the nuclei remain slightly flattened in the plane of division,

^ For details see Campbell (12), p. 61.

THE HOMOSPOROUS LEPTOSPORANGIAT^

353

as in the Hepaticae, and the mature spermatozoids are coiled
more flatly than in the Polypodiacese. The free spermatozoid
recalls that of Marattia or Equisetiim rather than that of the
Polypodiacese. There are but about two complete coils, and
the hinder one relatively larger than in the latter forms. In
swimming there is peculiar undulating movement, suggestive
of the spermatozoid of Equisctnm.

The Archc^onimn
The archegonia are only borne upon the large heart-shaped

o._

Fig. 196. — A, Ripe antheridium of O. Claytoniana, just ready to open; B, the same
discharging the sperm cells, X600; C, two spermatozoids, X1200; o, operculum.

prothallia, and occupy the sides of the projecting midrib, where,
if the earlier ones are not fertilised, they may continue to form
indefinitely ; but no correspondence can be made out between
them and the initial cells, and while developed for the most part
in acropetal order, new ones may arise among the older ones.
23

354

MOSSES AND FERNS

CHAP.

The mother cell of the archegoniuni is scarcely distinguishable
from the neighbouring cells, either in size or contents, and can-
not always be identified until after the first transverse divisions.
The development is much as in the other Ferns, but there are

some differences that may
be noted. The first trans-
verse division, as in these,
separates the cover cell from
the inner cell, and the latter
may divide into a basal and
:entral cell, but sometimes
chis division is omitted, and
the basal cell is absent. The
cover cell divides by the usual
cross - walls into the four
primary neck cells, which
here all develop alike, and the
neck remains straight. The
complete neck has about six
tiers of cells. The separation
of the neck and ventral canal
cells follows in the usual
manner, but occasionally the
former may be divided by a
transverse cell wall (Fig.
197, A), although ordinarily
the division is confined to the
nucleus. The neck cells have
small nuclei, and in the liv-
ing state are almost trans-
parent, with little chloro-
phyll. Small glistening bod-
ies, apparently of albumin-
FiG. 197.— A, Young ^ archegonium of o. ous uature, are ofteu present,

cinnatnomea, with the neck canal cell ^,-,(| ^^^ especially COUSpicU-
divided by a cell wall; B, a nearly ripe . * 1 r; 1 'j-I,

archegonium of the same species, X525. OUS 111 matCl lal tlXeCl Wltn

chromic acid. Kny and
Luerssen both speak of the quantity of starch in the axial row
of cells in O. regalis, but in neither O. cinnaniouica nor O. Clay-
toniana was this noticeable. As the egg approaches maturity
the nucleus becomes large and distinct, and one or two nucleoli

X THE HOMOSPOROUS LEPTOSPORANGIATJE 355

are present. The chromosomes are not conspicuous, a con-
dition that we have seen before is not uncommon in the o^gg
nucleus.

A curious appearance was noted several times just before
the archegonium seemed about to open, and after the formation
of the ventral canal cell. This was the separation from the
upper part of the tgg of a small body containing what looked
like a nucleus. Whether this is something analogous to the
"polar body" found in animal ova could not be determined.

When the archegonium opens, the four rows of cells bend
strongly outward, and frequently some of the terminal cells
become detached. A large receptive spot is present, and the
nucleus is smaller than in the younger ^gg, and contains more
chromatin, and usually but a single nucleolus.

Fertilisation

The horizontal position of the archegonia, as they project
from the sides of the midrib, makes it easier to follow the en-
trance of the spermatozoid than is the case in most Ferns. The
spermatozoids collect about the mouth of the freshly-opened
archegonium, and soon one finds its w^ay in. With the ciliated
end down, it revolves rapidly, not seeming to be much impeded
by the mucilage thrown out by the archegonium. Suddenly,
with a quick movement, quite unlike the slow worm-like move-
ment seen in most Ferns, it slips through the neck into the cen-
tral cavity, where its movement is resumed. After about three
or four minutes it disappears, and has presumably penetrated
the tgg. Other spermatozoids may make their way into the
central cavity, but only one penetrates the ovum. The lower
neck cells now approach, but not enough to prevent the entrance
of other spermatozoids. Within a few hours the inner walls
of the neck cells begin to show the brown colour that indicates
that fertilisation has been accomplished.

The ^gg quickly secretes a cellulose membrane, which pre-
vents the entrance of the other spermatozoids. The o^gg nu-
cleus moves towards the receptive spot at the time of fertilisa-
tion, where the spermatozoid may be seen but little altered in
form. It almost at once comes into contact with the female
nucleus, and the two then move toward the centre of the ovum.
Here the spermatozoid gradually loses its coiled form and con-

356

MOSSES AND FERNS

CHAP.

tracts until it becomes oblong, and in close contact with the egg
nucleus, in some cases looking as if it had penetrated the egg
nucleus as it does in Onoclca (Shaw (2)). The process is a
slow one, and in one case twenty-four hours after the entrance
of the spermatozoid the two nuclei were still recognisable.
Finally they are completely fused, and a single nucleus, with
usually, perhaps always, two nucleoli is seen. No sign of a
separation of the chromosomes of the copulating nuclei was
observed.

The Embryo

The first division of the ovum is the same with respect to
the archegonium as in Onoclca, i. c, the basal wall is parallel

Fig. 198.— a, Vertical section of an eight-celled tmbryo of O. Claytoniatta, X260.
Median longitudinal section of an older embryo of the same species, X260; C,
two transverse sections of a somewhat younger embryo of O, cinnamomea, X.26o;
St, stem apex; L, cotyledon; r, primary root; F, foot.

wnth its axis; but the quadrant wall is also parallel with this
instead of transverse, although its position with reference to the
axis of the prothallium is the same : so that the embryo-quad-
rants, and the organs derived from them, are situated like those
of the polypodiaceous embryo, with reference to the prothal-
lium, but not to the archegonium.

THE HOMOSPOROUS LEPTOSPORANGIAT/E

357

As in Onoclea the primary organs are established by the
first two walls, and the next divisions form octants, but there is
somewhat less regularity in the later divisions, in which respect
Osniunda is intermediate between the Polypodiaceai and the
Eusporangiatse. As in the former, the two epibasal quadrants
develop stem and cotyledon, the hypobasal ones, root and foot.
At this stage the cells of the young embryo contain but little
granular cytoplasm, and there are large vacuoles. As the
embryo growls older the granular cell contents increase in quan-
tity. The subsequent divisions follow very closely those in the
embryo of Onoclea, but are less regular, and the embryo retains
for a longer time its original nearly globular form.

Fig. 199. — Three sections of one embryo of O. cinnamomea in which the root (r) is
especially well marked, X260. Lettering as in the last.

The direction of growth of the cotyledon is determined in
part by the first walls in its primary octants. The outer octant
usually becomes at once its apical cell, and if its first segment
is formed on the side next the octant wall, this throws the axis
of growth very much to one side, so that the axis of the leaf
may be almost at right angles to the median line of the embryo.
Otherwise it nearly coincides wath this. The original three-
sided apical cell persists for a long time, and it could not be
positively shown whether or not it was afterwards replaced by

358

MOSSES AND FERNS

CHAP.

a two-sided one. The further development of the cotyledon
corresponds almost exactly with Onoclca. It does not break

Fig. 200. — A, Horizontal section of an advanced embryo of O. Claytoniana, passing
through the cotyledon and foot, X230; B, longitudinal section of the stem apex
in a somewhat older embryo of O. cinnamomea, X460; C, transverse section of
the apex of the primary root of the same, X460.

through the calyptra until later, and in this respect shows its
primitive character. The single vascular bundle of the petiole

Fig. 201. — Transverse section of a prothallium of O. Claytoniana, showing the lateral

position of the embryo (etn), X7S-

approaches the collateral type, and is much like that of the
cotyledon of Marattia. Stomata of the usual type occur on

X THE HOMOSPOROUS LEPTOSPORANGIATJE 359

both sides of the lamina. The development of the stem offers
no peculiarities. The apical cell is of the tetrahedral form
found in the mature sporophyte.

The root is bulky, and the apical cell relatively small, with
large segments, dividing less regularly than in Onoclea, and on
the whole approaches most nearly to Botrychiiun. The form
of the apical cell is like that of Onoclea or Botrychium, and is
interesting because in the later roots this is replaced by another
type, so that this would indicate that the three-sided form
found in so many cases is the primitive condition. The vas-
cular bundle is diarch.

The foot is very large, and while formed originally from
the upper hypobasal quadrant, it encroaches more or less upon
all the others. Very early its
cells cease to show any regular
order in their divisions, and di-
vide more slowly than the other
cells of the embryo, so that they
become decidedly larger. The
cells lose much of their proto-
plasm as they increase in size,
and serve simply as absorbent
organs. They are in close con-
tact with the prothallial cells,
and crowd upon them until the ^^^^ ^o^.-Young sporophyte of o.

foot penetrates deep into the Claytoniana, still attached to the

,1 11- 1 11 -i prothallium, X6.

prothallium, whose cells it par-
tially destroys. It Is upon the large development of the foot,
whose outer cells are sometimes extended into root-like exten-
sions like those in Anthoceros, that the young embryo is main-
tained so long at the expense of the prothallium.

Frequently more than one embryo begins to develop, and
sometimes a number of archegonia may be fertilised; but no
cases were met with where more than one embryo came to
maturity, although it Is quite possible that this may occur.

In all the Osmundacese the mature stem Is a stout rhizome,
which In the genus Todea may form an upright caudex, a metre
or so In height. The bases of the stipes are broadly winged
and these sheathing leaf-bases persist for many years, com-
pletely covering the surface of the stem. According to Faull
(i)^ who has made a very thorough study of the anatomy of

36o

MOSSES AND FERNS

CHAP.

the Osmundaceae, the stem usually bifurcates once, into branches
of equal size, which may rarely fork once more.

A section of the rhi-
zome (Fig. 203, B),
shows a massive cortex
composed largely of dark
sclerenchyma, but the in-
ner cortex is parenchym-
atous. The central cyl-
inder is bounded by an
endodermis, w i t h i n
which are from one to
four layers of cells con-
stituting the pericycle.
Faull ( ( I ) , p. 7) was un-
able to verify Strasburg-
er's statement, that both
the endodermis and peri-
cycle in Osiniinda, as in
the other Ferns examined
by the latter ((11), p.
449), are of cortical or-
igin.

Inside the pericycle is
a continuous cylinder of
phloem, whose outer cells
constitute the proto-
phloem. The phloem
proper consists mainly of
sieve-tubes of large size
and with conspicuous
sieve-plates upon their
lateral faces. The so-
called "quergestreckte-
zellen" of Zenetti (Fig.
204, qu) are considered
by Faull to be sieve-tubes.
The woody strands form a reticulate cylinder, and in cross-
sections of the stem appear as a circle of horse-shoe shaped
masses of wood lying inside the phloem, and separated from
each other by the medullary rays. The tracheary tissue con-

FiG. 203. — upper part of a sp^iophyll of O. Clay-
toniana, X2; sp, sporangia; B, section of the
rhizome of O. regalis, showing the arrange-
ment of the vascular bundles, X4 (after
De Bary).

THE IIOMOSPOROUS LEPTOSPORANGIAT^

361

sists of small ringed and spiral elements constituting the proto-
xylem, and larger scalariform metaxylem tracheids. In O.
cinnamonica, Faull found an internal endodermis and traces of
internal phloem, which are quite absent in the other species,
where the xylem-masses are in direct contact with the pith.
Faull considers the condition in O. cinnamornea as the primitive
condition from which the type found in the other species has
been derived by a suppression of the inner phloem and endo-
dermis.

A. B.

fe o

iecs

'<a

F13. 204. — Osmunda rcgalis. A, Part of the central cylinder of the rhizome, X250;
B, a sieve-tube, more highly magnified. (After Zenetti.)

The leaf traces (Faull (i), p. 20) pass very obliquely
through the cortex into the leaf base. They are concentric in
structure. The protoxylem is situated on the inner face of the
xylem strand and is continuous with that of the stem. Each
leaf trace is surrounded by a sheath of colourless cells.

The Leaf

The origin of the leaves is the same as in the Polypodiaceae,
but the young leaf grows from a three-sided apical cell much

Z'02 MOSSES AND FERNS chap:

like the stem (Bower (ii), Klein (2)), and the young leaf is
more conical than in the Polypodiaceae. In the very young
leaf, according to Bower, one side of the apical cell is always
directed toward the stem apex, and never one of the angles.
In the presence of a three-sided apical cell, as well as its more
cylindrical form, there is an approach to BotrycJiiimi. The
further development of the leaf is like that of the pinnate leaves
of the Marattiacese or Polypodiaceae, with which they agree
also in the strongly circinate vernation. The leaves are always
pinnately divided, and are similar in all the species, and the type
of venation is the same. While in all species of Osmunda and
in Todca harhara, the structure of the leaf is quite like that of
Polypodiaceae, the other species of Todea (Lepfopteris) have
the lamina of the leaf reduced to two or three lavers of cells, and
there are no stomata. The texture of the leaves in these forms
is filmy, like that of Hymenophylliim.

The petiole is traversed by a single large vascular bundle,
which in section is crescent-shaped and in structure concentric,
with the elements like those of the Polypodiaceae, but the endo-
dermis is not so clearly differentiated; and close to the inner
side of the bundle are numerous mucilage cells, recalling the
tannin ducts of Angioptcris. A further point of resemblance
to the Marattiaceae is the presence of stipular wings at the base
of the petiole. The chaffy scales (paleae) so common in the
Polypodiaceae are quite wanting, but hairs are developed, often
in great numbers. Thus in O. cinnamomea the young leaves
are covered completely with a felted mass of hairs, recalling
those in some of the Cyatheaceae. Some of these are gland-
ular. The sterile leaves and sporophylls are either very much
alike, as in Todca, or the sporophylls may be very different.
An extreme case is seen in O. cinnamomea, where the whole
sporophyll is devoted to the development of sporangia. In
this species, as well as O. Claytoniana, the sporophylls develop
first and form a group in the centre of a circle of sterile leaves.
In O. cinnamomea the sporophylls develop no mesophyll, and
die as soon as the spores are scattered.

The Root

The roots of the mature sporophyte differ very markedly
from those of the other Leptosporangiatae, and have been the

THE HOMOSPOROUS LEPTOSPORANGIAT^

363

subject of numerous investigations, but there still is a good
deal of diversity of opinion as to their exact method of growth.
Bower ( (11), p. 310) states that in O. regalis there may be a
single apical cell, such as exists in the first root of O. Claytoni-
ana and O. cinnamomea, but that it never shows the regular
segmentation of the typical leptosporangiate root, and it may
be replaced by two or three similar initials. In Todea harhara
he found four similar initials, and in no case a single one,
although Van Tieghem and Douliot ((5), p. 378) ascribe to
this species a single three-sided apical cell.^

Fig. 205. — A, Longitudinal section through the root apex of O. cinnamomea ; t, young
tracheids, X200; B, cross-section of root apex of O. Claytoniana, X200.

Osmunda cinnamomea (Fig. 205, A) shows a single very
large initial, more or less triangular in form when seen in pro-
file, but with the point sometimes truncate. Transverse sec-
tions show that it is really a four-sided pyramid. The young
segments are very large, and it is possible that these may some-
times assume the role of initials. Owing to the slowness and
irregularity of cell division it is difficult to trace the limits of
the segments beyond the youngest ones. They usually form

* Lachmann (i) asserts, however, that he found a group of initials such
as Bower describes.

364 MOSSES AND FERNS

CHAP.

a spiral, but cases were sometimes encountered where the seg-
ments were apparently cut off in pairs from opposite sides of
the initial cell. The root-cap arises in part from special seg-
ments cut off from tlie outer face of the apical cell, but also in
part from the outer cells of the lateral segments, as in the Eu-
sporangiatse. The separation of the tissue system follows
much as in Botrychiuni. The central cylinder is large and oval
in section, but witli poorly-defined limits, and it is not possible
to state positively whether it owes its origin exclusively to the
innermost cells of the segments. The large central tracheae,
as in Adiantuin, are very early distinguishal)le. O. Claytoni-
ana agrees on the whole with O. cinnanwmea, but the divisions

Fig. 206, — Osmunda regalis. A, Section of young sporophyll passing through three
very young sporangia; B, longitudinal section of an older sporangium; t, the
tapetum, X325 (after Bower).

are much more regular, and it approaches nearer the typical
leptosporangiate type, both in the arrangement of the young
tissues and in the structure of the fully-developed vascular
bundle, which closely resembles that of the PolypodiacCcT, and
differs from the investigated species of Osmunda and Todea in
the better development of the endodermis, and in having the
pericycle of but one or two layers. The vascular cylinder of the
root is typically diarch like that of the PolypodiacCcX, but ex-
ceptionally (Faull (i), p. 22), it may be triarch.

The roots arise regularly, two at the base of each leaf
(Lachmann (7), p. 118), and their bundles connect with those
of the stem near the bottom of the elongated foliar gap in its
vascular cvlinder.

THE HOMOSPOROUS LEPTOSPORANGIATJE

365

The Sporangium

The sporangia in Osmund a are produced upon sporophylls
that closely resemble those of Bofrycliinm or H elminthostachys ,
but in Todca they occur upon the backs of the leaves, as in
most Ferns. In structure and development they are intermedi-
ate between the true leptosporangiate type and the eusporangi-
ate. So far as they have been investigated they all correspond
very closely. The origin of the sporangia is almost identical
witli that in Botrychhim, and more than one cell may take part

Fig. 207. — A, Pinnule of a fertile leaf of Todea (Leptopteris) hymenophylloides, X2;
B, fertile pinnule of Osmunda Claytoniana, X3; C-E, three views of the ripe
sporangium of O. cinnarnomea, X40; F, G, sporangia of Todea Iiymenopliylloidcs,
X40; r, annulus.

in their formation (Bower (ii); Goebel (17)). Bower
says: "In all cases, however, one cell distinctly takes the lead,
and this we may call the initial cell (Fig. 206, A) ; but the
arrangement of its division wall does not, as in the true lepto-
sporangiate Ferns, conform to any strict plan ; the initial cells
are oblong, seen in vertical section, and the first divisions are
longitudinal, so as to meet the basal wall : both in the segment
thus cut off and in the central cell, periclinal or sometimes
oblique divisions may take place, so that a considerable bulk of

366

MOSSES AND FERNS

cha:\

tissue is formed, in the projecting apex of which a single large
cell occupies a central position." As in BotrycJihim the arche-
sporium is derived from a single hypodermal cell, which ap-
proaches more or less the tetrahedral form of the true Lepto-
sporangiates, but shows a good deal of variation. As in these
the wall of the sporangium is only one-layered, and the tapetum
ordinarily two, but occasionally three-layered. The fully-de-
veloped sporangium is in shape much like that of Botrychhim
Virginianuin, and has a very short massive stalk. Like Hcl-
ininthostachys and Angioptcris, it opens by a vertical cleft, and
like the latter there is a rudimentary annulus consisting of a
group of thick-walled cells (Fig. 207, r).

The Gleicheniace^

These comprise about twenty-five species of tropical and

sub - tropical Ferns,
which may be all placed
in two genera (Diels
( I ) ) — Stromatopteris,
with a single species S.
monilifor m i s and
GleicJienia with about
25 species. The best
known is G. dichotoma,
an extremely common
Fern of the tropics of
the whole world. It has
very long leaves, which
fork repeatedly, and

Fig. 20?,.—Glcichcnia pcctinata. ProthaIHa, X4; may bc prolifcrOUS from

B, a large prothallium seen from below, show- , 4-1^111

ing a dichotomy of the apex; C, the young ^^^^ grOWtll OI DUCiS Cle-

sporophyte attached to the prothallium. VCloped ill the axils of

the forked pinnae.

The Gamctophytc

The development of the prothallium has been studied by
Rauwenhoff ( i ), and shows some interesting points in which it
is intermediate between the Osmundace^e and the other Lep-
tosporangiatse. The spores of Gleichenia are usually tetra-

THE HOMOSPOROUS LEPTOSPORANGIATJE

367

hedral, and contain no chlorophyll. When the ripe spores are
sown, after a few days the oil-drops become much smaller but
more numerous, and the first chloroplasts become evident.
The latter increase in number and size, and small starch grains
are developed. The exospore is ruptured in from tw^o to three
weeks from the time the spore is sown, and the spore contents
surrounded by the intine project through the opening. The
first wall usually separates the first rhizoid, which, like that of
Osmiinda, often contains a good deal of chlorophyll, from the
larger prothallial cell. As a rule the development of the pro-
thaliium corresponds closely to that of the Polypodiacese, but

Fig. 209. — Gleichenia pectinata. A, Ripe archegonium; B, nearly ripe antheridium ; i,
surface view; 2, optical section; C, apex of open antheridium, showing the method
of dehiscence; D, section of very young antheridium. All figures X about 250.

it may have a midrib like that of Osmunda. The growth is
normally from a two-sided apical cell, which is replaced later
by marginal initials. A point of resemblance to Osmunda is
the abundant production of adventitious shoots, which are
formed in numbers upon the margin or from the ventral sur-
face, and may develop into perfectly normal prothallia.

Rauwenhofif's account of the sexual organs is not as com-
plete as might be wished, but is sufficient to show some inter-
esting points of resemblance to the Osmundacese. The first wall
in the antheridium cuts off a basal cell, and the next wall is
somewhat like the funnel-shaped wall in the Polypodiaceae.

368

MOSSES AND FERNS

CHAP.

The dome-shaped wall next formed is here not so marked,
being nearly flat.^ No definite cover cell is cut off, but the
upper cell appears to divide by a single wall running obliquely
over the apex, somewhat as in Osniunda. The divisions in
the central cell offer no peculiarities, and the spermatozoids
resemble those of other Ferns. The archegonia are formed on
the forward part of the midrib, but are not confined to the
sides, as in Osiuuuda. Apparently a basal cell is not always
formed, but as to this and the much more important point, the
number and character of the canal cells, Rauwenhoff says noth-
ing definite. The neck is long and straight, like that of Os-
miinda and the Hymenophyllace?c.

Fig. 2IO. — A, Diagram of the tissues of the rhizome in Glcichenia Habellata, X8; B,
section of the stele (somewhat diagrammatic) of G. pectinata, X26; C, part of
the stele of G. dichotoma, X3S0. (All figures after Boodle.)

In G. pectinata (Fig. 209) the resemblance of the anther-
idium to that of Osmunda is much more striking than in the
species studied by Rauwenhoff. The archegonium in this
species showed a division of the nucleus of the neck canal cell.

* Rauwenhoff's statement that the central cell of the antheridium con-
tains chlorophyll, to judge from his Fig. 58, which illustrates this, is based
upon a pathological case. The absence of chlorophyll from the central cells
of the antheridium is a very constant character in all Archegoniates.

THE HOMOSPOROVS LEPTOSPORANGtAT^.

369

The Embryo

To judge from the few rather vague statements made by
Rauwenhoft* in regard to the embryo, this more nearly re-
sembles the typical leptosporangiate type than it does Osnmnda.
The primary root has a large and definite three-sided apical cell,
and the divisions in the segments are very regular.

The Adult Sporophyte

Poirault ( i ) and Boodle (3) have made a study of the stem
of various species of Gleichenia, which differs a good deal from

Fig. 211. — Gleichenia flabellata. Development of the sporangium; A, B, X300; C,

X150. (After Bower.)

that of Osmiinda, and approaches that of the Hymenophyllacese
and Schizgeaceae. A single axial bundle traverses the stem, and
is separated from the sclerenchymatous cortex by a distinct en-
dodermis. Within the latter is a pericycle of several layers
of cells, within which is a continuous zone of phloem containing
large and small sieve-tubes, and phloem parenchyma. Within
the phloem are also secreting cells. The whole central part of
the stem, except in G. pectinata, is occupied by bundles of large
scalariform tracheids separated by parenchyma (Fig. 210, C).
The single bimdle traversing the petiole is much like that of

370

MOSSES AND FERNS

CHAP.

Osmiinda, and the lamina of the leaf does not show any peculi-
arities. In G. pcctinata (Boodle (3) ) , the stele is a hollow cyl-
inder with both internal and external phloem and endodermis
(Fig. 210, B).

The Sporangmm

The development of the sporangium has been studied by
Bower (19). The young receptacle begins to develop while
the leaf is still tightly coiled. From the margin of the circular
receptacle, and in some cases also from its upper surface, the

Fig. 212.— a, Pinnule of Gleichenia dichotoma, showing the position of the sori (5),
X4; B, ventral; C, dorsal view of the ripe sporangium, X85.

young Sporangia arise as small conical outgrowths. Each spo-
rangial outgrowth undergoes a series of regular segmentations
resulting in a central, nearly tetrahedral, sporangial cell, from
which successive segments are cut off which give rise to the
short, massive stalk of the sporangium. Finally a periclinal
wall is formed resulting in the archesporium. The further de-
velopment is much like that of Osiminda, except that the inner of
the two layers of tapetal cells become very large and their nuclei

THE HOMOSPOROUS LEPTOSPORANGIAT^

371

may divide (Fig. 211). At this stage there is a marked re-
semblance to the sporangium of Angioptcris, and Bower calls
attention to the similarity in form between the sorus of Gleich-
enia and that of the Marattiaceae. The walls of the inner
tapetal cells are finally absorbed. The number of sporogenous
cells is large, the number of spores in G. Hahcllata amounting
sometimes to over 800.

In G. dichotoma (Fig. 212) the sporangia form rounded
naked sori above the terminal branch of a lateral vein. They
are pear-shaped, with a very short stalk, and upon the outer
surface is a nearly complete very distinct annulus composed of

Fig. 213. — Matonia pectinata. A, Base of fertile pinna, X3; B, section of the sorus;
C, open sporangium, X35; D, section of rhizome, Xio. (A, B, after Diels; D,
after Seward.)

a single row of large thick-walled cells. This is interrupted
at the top of the sporangium by three or four narrow thin-
walled cells, and starting from this point and extending along
the median line of the ventral surface are two rows of narrow
cells, between which the sporangium opens.

The Matoniace^

The family Matoniaceae is represented by the single genus
Matonia (Fig. 213), with two species, M. pectinata and M. sar-

Z72 MOSSES AND FERNS chap.

mentosa, both of limited range, and confined to the Malayan
region. The affinities of Matonia are probably with the
Gleicheniacese, rather than with the Cyatheace?e, with which
they were formerly associated. The large flabellate leaves of
M. pcctinata are much like those of some species of Glcichenia,
and the arrangement of the sori is much the same. There is,
however, a conspicuous umbrella-shaped indusium of firm tex-
ture, and in their form and dehiscence the sporangia are more
like those of the Cyatheace?e. The development of the spo-
rangium, according to Bower (19), is much like that of
Glcichenia.

The structure of the stem in Matonia pcctinata (Seward
(2) ) is very much like that of Glcichenia pcctinata, but there is
a second and sometimes a third cylindrical stele within the
primary stele (Fig. 213, D).

Zeiller (i) from a comparison of Matonia with the fossil
genus Laccopteris, which occurs in early Jurassic beds, con-
cludes that the two genera are very closely related, if not actu-
ally identical, and represent the earliest forms of the Cyathe-
acege, and that Matonia is the last remnant of a family now in
process of extinction.

The Hymenophyllace^

The Hymenophyllace?e have been the subject of much dis-
cussion on account of the assumption made by all the earlier
writers that they were the most primitive of the Pteridophytes.
This was based very largely upon the apparent resemblance
between the delicate sporophyte of many of them and the leafy
gametophore of the Mosses. More recent study of their de-
velopment, especially the gametophyte, has led to a modification
of this view, although it is still held by many botanists. It
seems more probable that the peculiarities of IxDth gametophyte
and sporophyte are due to the peculiar environment of these
plants, which grow only in very moist places, indeed are almost
aquatic at times. They are for the most part extremely deli-
cate Ferns of small size, and with few exceptions are tropical.
Many are epiphytes, and these have the roots very poorly de-
veloped or even entirely wanting. The leaves are, with few
exceptions, reduced to a single layer of cells, except the veins,
which gives them a striking resemblance in texture to the leaves

THE HOMOSPOROUS LEPTOSPORANGIATAi

373

of some of the larger Mosses, c. g., species of Mniiuii. Hooker
( I ) reduces them all to three genera, which, however, are often
further divided. Of these Loxsoma is represented by but one
species, L. Cunninghamii, a form which seems to be intermedi-
ate in general characters between the Cyatheacese and the other
Hymenophyllace?e, but its life history and anatomy are not
known. Of the other genera Hooker gives seventy-one species
to Hymenophylhim and seventy-eight to Trichomanes.^

The GametopJiyte

The gametophyte is known more or less completely in sev-
eral species of both Trichomanes and Hymenophylhim. The

Fig. 214. — Trichomanes Draytonianum. Germination of the spores, X52S; r, primary

rhizoid.

large spores germinate promptly, but their subsequent develop-
ment is very slow. They contain chlorophyll and often begin
to germinate within the sporangium, where they may often be
found divided into three equal cells by w^alls radiating from the
centre (Fig. 214). All of the cells begin to grow out into
filaments, but usually only one of them develops into the pro-
thallium, the others dividing only once or twice, and forming
short brown rhizoids. In some species of Trichomanes, e. g.

*The number of species known now considerably exceeds this.

374

MOSSES AND FERNS

CHAP.

T. pyxidiferuin (Bower (8)), the prothallium remains fila-
mentous, and forms a densely branching structure very much
like the protonema of some Mosses, but coarser in texture.
Other species, however, c. g., T. alatiim, produced flattened
thalloid prothallia from branches of the fllamentous forms, and
HymcnophyUiim always has a flat hepatic-like prothallium,
which in its earlier stages, according to Sadebeck ((6), p.
i6i), always develops a two-sided apical cell, and differs in no
wise from that of other Ferns. These prothallia, however,
remain single-layered throughout, although they reach an ex-
traordinarily large size, and branch much more freely than
those of most other Ferns (Fig. 215). The rhizoids are
always very short and dark-coloured, and generally occur in

....$

Fig. 215. — HymcnophyUum (sp). A, Large prothallium of the natural size; B, part of
the margin of one of the growing branches, showing two similar initial cells, Xi8o;
C, a filamentous male prothallium derived from a bud, X6o.

groups Upon the margin only. The branching of the prothallia
is either monopodial or dichotomous, and the latter method
may be repeated a number of times. They may live for an in-
definite time apparently. The writer has kept prothallia of
both Trichomanes and HymcnophyUiim for nearly two years,
at the end of which time they showed no diminution of vigour.
They form ordinary adventitious shoots, but there are also
special gemmae developed in many of them, often in great num-
bers. In an undetermined species of HymcnophyUiim col-
lected in the Hawaiian Islands (Fig. 216) these gemmre oc-
curred very abundantly upon prothallia that had ceased to form
sexual organs, A marginal cell grows out and curves upward,

THE HOMOSPOROUS LEPTOSPORANGIAT^

375

and the tip is cut off by a transverse wall from the basal cell-
In the terminal cell are next formed a series of vertical walls,
which transforms it into a row of cells extended at right angles
to the axis of the pedicel. One of the central cells now bulges
out laterally, and this papilla is cut off by an oblique wall and
forms the beginning of a short lateral branch, so that the fully-
developed bud has somewhat the form of a three-rayed star,
and in this condition becomes detached and grows into a new
prothallium. The prothallia formed in this way often do not

Fig. 216.— Hymenophyllum (sp). Margin of a prothallium with numerous gemmae k;
X85; B, a young gemma, X260; st, its stalk.

develop a flat thallus, but may remain filamentous, and each
ray may produce antheridia either terminally or laterally (Fig.
215, C). In case a flat thallus is formed, only one or some-
times two of the rays grow out in this form, the other having
only a limited growth, and terminating in a short rhizoid. In
short, the process is very similar to that in the germinating
spores.

37(3

MOSSES AND FERNS

CHAP.

The Sexual Organs

Bower (8) has investigated the structure of the anther-
idium in Trichomanes, and Goebel (lo) in both Trichomanes
and Hymenophyllum. My own study of their development
has been confined to an undetermined species of Hyuienophyl-
him from the Hawaiian Islands, but the results of my observa-
tions agree entirely with those of other observers. The anther-
idia arise mainly upon the margin of the prothallium, or upon
the ends of the filamentous ones. After the mother cell is cut

Fig. 217. — Hymenophyllum (sp). Development of the antheridium, X260. A, D,
From living specimens; E, microtome section; B i, C 2, D i, optical sections;
B 2, C I, D 2, surface view of the same.

off, there is usually formed another transverse wall, by which
a short pedicel is produced. A funnel-sha])ed wall does not
ever seem to be formed, but the next division walls are more
like those in Osmunda, and extend only part way round the
circumference of the mother cell. After a varying number of
basal cells are thus formed, a dome-shaped wall arises, separat-
ing the central cell. This wall is not so convex, as is usually
the case in the Polypodiacere, and in this respect, as well as the
form of the wall cells, the antheridium resembles that of Glcich-

THE IIOMOSPOROUS LEPTOSPORANGIAT^

Zll

enla. In the Hymenophyllacege no cap cell is formed, but as in
Osmunda and Gleichenia, the upper cell is divided l^y walls
running over the apex. The divisions in the central cell and
the structure of the spermatozoids, so far as these have been
studied, correspond with those of the other Leptosporangiatse.
A single archegonial cushion is not formed, Imt the arche-
gonia occur in small groups at different points upon the margin.
Goebel ( lo) has shown, however, that these archegonial groups
arise hrst near the growing point of the prothallial branch, and
that they are simply separated by the intervention of zones
of sterile tissue. At the point where they arise the prothallium
becomes more than one cell thick, and in all cases where the
development could be certainly followed, the archegonium
arose from one of the ventral cells, and never directly from a
marginal cell. The details of the development have not been

Fig. 2i8. — Part of the filamentous prothallium and archegoniophores of Trichomanes
rigidum. (After Goebel.)

followed, and whether there is any division of the neck canal
cell is not known. The neck is straight, as in Osmunda and
Gleichenia.

In Trichomanes the archegonial meristem (archegonio-
phore) may be formed as a short branch, directly upon the fila-
mentous prothallium.

The lateral walls of the prothallial cells are in all the species
thicker than is the case in most Ferns, and there are distinct pits
in them. In the rhizoids a parasitic fungus is frequently
found.

The embryogeny is almost unknown (Janczewski (2) ), but
the first divisions and the very young sporophyte correspond

3/8

MOSSES AND FERNS

CHAP.

closely with those of the other Leptosporangiatae. The coty-
ledon is simple with a single median vein, and a root is present
in all species yet examined.

The Mature Sporophyte

Prantl ( i ) has given a very complete account of the struc-
ture of the mature sporophyte, and Bower ( 1 1 ) has added to
this bv a careful studv of tlie meri stems of the different orsfans.
From the investigations of the latter it seems that here, as in
nearly all other Ferns, the stem apex has the usual three-sided

Fig. 219. — Pinna of the leaf of HymcnopJiyllum rccurfum, X3; B, part of rhizome (r)
and leaf of Trichomanes parvulum, X3; C, pinna of the leaf of Trichomanes
cyrtotheca, X3; D i, trumpet-shaped indusium of the same, X4; 2, section of the
indusium {id) with the central sorus, X5; ^, the sorus.

initial cell, but only a small part of the segments give rise to
leaves, which are arranged in two ranks.

The stem in all investigated Hymenophyllaceae is mono-
stelic, and one leaf-trace passes to each leaf. The cortex is
usually largely made up of sclerenchyma, especially the inner
cortex. In Hynnenophylhnn rccurvum (Fig. 220), the axial
vascular bundle is strictly concentric. Occupying the centre
is a curved band of tracheary tissue, the small central tracheids
being the protoxylem. Around the xylem is a continuous zone

THE HOMOSPOROUS LEPTOSPORANGIATM

379

of phloem, separated from the endodermis by a broad pericycle.
In other species of Hymcnophylhim, Boodle (i) found a dif-
ferent arrangement of the xylem and phloem. In some cases,
e g., H. scabriim, there are two xylem plates, with the proto-
xylem elements in the conjunctive tissues between them.

In Trichomanes there is also a good deal of variation. Fig.
220, B, shows the structure in T. vcnosmn, a small species from

Fig. 220.— a, Section of the rhizome of Hymenophyllum recurvum, X about 40; B,
rhizome of Trichomanes venosum, X about 75; C, stele of B, more highly mag-
nified; D, root of Hymenophyllum recurvum, X about 75; E, stele of the root
more highly magnified.

Australia and New Zealand. The structure of the stem dif-
fers from that of Hymenophyllum recurvum, mainly in its
greater delicacy. The sclerenchyma of the cortical region is
less developed, and the concentric axial cylinder corresponding
to its much smaller size has both the xylem and phloem reduced

in amount.

In the stouter species, like T. radicans, the amount of wood

38o MOSSES AND FERNS chap.

is much greater. According to Boodle (1. c. Fig. 24), there
are two or three protoxylems, accompanied by parenchyma
cells, surrounded by a massive ring of large tracheids. There
is an approach in this species, and still more in T. rcniforme,
to the form characteristic of Hyincnophylhnn scahrum and its
allies. In the small species, T. muscoidcs, apparently by reduc-
tion, the stele becomes collateral, and this, according to Prantl
( ( I ) , p. 26) , is the rule in the sub-genus Hcmiphlchium, where
the xylem lies on the ventral side of the stem, the phloem on the
dorsal side. The pericycle, at certain points, shows clearly its
common origin with the endodermis. Van Tieghem (3) con-
siders that there is a double endodermis, and that no true peri-
cycle is present. In T. labiafum {T. iiiicropJiylliim) Giesen-
hagen ( i ) found the bundle reduced to a single tracheid sur-
rounded by four or five parenchyma cells immediately within
the endodermis. The reduction is carried still further in T.
Motleyi, where tracheary tissue has entirely disappeared from
both stem and sterile leaf. In the sporophylls, however, trach-
eary tissue is present (Karsten (2), p. 135).

TJie Leaf

The observations on the earliest stages of the leaf are very
incomplete, but in some cases at least a two-sided apical cell is
present. In those with palmately lobed or entire kidney-shaped
leaves, the later growth is marginal, and of the same type found
in similar leaves among the Polypodiace?e. The venation in
these forms is exclusively dichotomous, in those with pinnate
leaves, c. g., Trichomancs radicans, this is only true of the last
formed veins.

\Y\\\\ the exception of a very few species, e. g., T. rcniforme,
H. dilatatuiu, where the mesophyll of the leaves is three to four
cells thick, the whole lamina, with the exception of the veins, is
single-layered, and of course stomata are completely absent.
The form of the leaf is either pinnate, as in the larger species
of Trichomancs and Hymcnophyllum (Fig. 219), reniform
(T. rcniforme), or palmately divided (T. parvulum. Fig. 219,
B). The smaller veins, as in other Ferns, have collateral vas-
cular bundles, and in the smallest ones the xylem may be re-
duced to a single row of tracheids. The latter may be spiral,
reticulated, or scalariform. In the phloem Prantl could not

X THE HOMOSPOROUS LEPTOSPORANGIATJE 381

distinguish any well-marked sieve-tubes, but it was mainly com-
posed of bast fibres and caml)iform cells, and in Honiphlcbium
{Trichomanes) Hookcri the phloem is absent from the very
much reduced smaller veins. This is possibly an intermediate
condition between the normally developed bundles of the veins
of most species and the so-called pseudo-veins, in which there
is no tracheary tissue developed, but which in their origin cor-
respond to the ordinary veins. The petiole always has a single
vascular bundle, usually of typical concentric structure, but in
the section Hciniphlcbium Prantl states that it is collateral.
The ground tissue of the petiole is largely composed of scleren-
chyma like that of the stem.

The Roots

The development of the roots has been studied only in a
very few species. Bower (11) states that in T. radicans and H.
demissiun it ''conforms to the normal type for the root of lep-
tosporangiate Ferns, as described by Nageli and Leitgeb," but
does not go into details, and Prantl makes an equally brief
statement. While lateral roots are completely wanting in the
section Hemiphlehium, where their place is taken by leafless
branches, in most of the other forms they are developed in
considerable numbers. There is, according to Prantl, great
variation in the arrangement of the parts in the vascular cyl-
inder. Thus while all the species of Hymenophylhim have
diarch bundles, that of Trichomanes pyxidifenim is monarch,
while in one species, T. hrachypus, as many as nine primary
xylem masses are found. The Marattiacese alone, among the
other Ferns, show such great variability.

Trichomes occur, but not so abundantly as in most of the
Leptosporangiatse. They have usually the form of hairs,
which are either temporary (those formed on the margins of
the young leaves) or persistent for a longer time, like those
that cover the end of the stem apex and bases of the petioles in
many species.

The Sporanghim

All of the Hymenophyllace?e agree closely in the position of
the sporangia, whose development has, however, been studied
in detail only in Trichomanes ; but from the close correspond-

382

MOSSES AND FERNS

CHAP.

ence in other respects it is not likely that Hymenophyllum dif-
fers essentially from the latter. The sorus occupies the free
end of a vein, which often continues to grow for a long time
in Trichomanes, and forms a long slender placenta or colum-
ella, upon which the sporangia arise basipetally. While the

sp.

Fig. 221. — Trichomanes cyrtotheca. Development of the sporangium, X225. A,
Longitudinal section of very young receptacle with the first sporangia (sp) ; B-D,
successive stages of development seen in longitudinal section; F, horizontal section
of nearly ripe sporangium; r, the annulus.

receptacle is still very young the tissue of the leaf immediately
about it forms a ring-shaped ridge, which grows up in the form
of a cup-shaped indusium, which either remains as a tube

X THE HOMOSPOROUS LEPTOSPORANGIAT^ 383

(Trichomancs) or is divided into two valves (Hymenophyl-
liun). Many species of the former genus, however, show an
intermediate condition, with the margin of the indusium deeply
two-lipped.

The first sporangia arise at the top of the placenta (Fig.
221), but the apex itself does not usually develop into a spo-
rangium. After the first sporangia have formed, new ones
continue to develop. Near the base of the placenta a zone of
meristem is formed, which constantly contributes to its growth,
and the young sporangia arise from the surface cells formed
from this meristem. The mother cell is very easily distin-
guished by its larger size and denser contents. About every
third cell seems to develop a sporangium, but this probably is
not absolutely uniform. The first wall is usually nearly vertical,
and cuts off a narrow segment from one side of the mother cell
(Fig. 221, A). This in most cases examined was next fol-
lowed by a wall almost at right angles, separating a small basal
cell. After these preliminary divisions, which form the very
short stalk, the next divisions are exactly as in the Polypodi-
acese, and give rise to the central tetrahedral cell with the four
peripheral ones. Prantl ( ( i ) , p. 39) states that the first divi-
sions of the cap cell are also spirally arranged. In T. cyrto-
theca (Fig. 221) the tapetum is massive, and composed
throughout of two layers. The archesporium divides into
eight cells, whose further history is the same as in other Ferns.
The annulus in the Hymenophyllacese is large, and situated
much as in Gleichenia. According to Prantl, it arises in part
from the cap cell and partly from numbers one and three of the
primary peripheral cells. Where the young sporangium is cut
longitudinally (Fig. 221), the annulus cells are at once recog-
nised by their larger size, especially upon the dorsal side.
Their radial and inner walls become very thick, and a horizontal
section (Fig. 221, F) shows that the annulus is not complete,
but is interrupted on the inner side where the stomium is formed.

Apogamy and Apospory

Both of these phenomena have been discovered by Bower
(8) to occur not infrequently in Trichouianes, and probably
further investigations will reveal other instances. Apogamy
was common in T. alatuni, in which species archegonia were

384

MOSSES AND FERNS

CHAP.

not seen at all, and the origin of the young sporophyte was un-
mistakal)ly non-sexual. Prothallia, arising directly from the
leaf, or from the sporangial receptacle, were found to be a com-
mon phenomenon in the same species.

The ScHiZyEACE.E (Dicls (i))

The SchizcTace?e include about sixty species Monging to
five genera. The very characteristic sporangia have a terminal
annulus, which forms a sort of crown at the apex. Some of
them, like Schizcca pnsilla and T radio ptcris clcgans, are very

^- B.

Fig. J-J2. — A, Prothallium of Ancimia Phyllitidis, Xi8o; B, female; C, male, prothallia
of Scliicaea pnsilla, X30 (A after Bauke, B, C, after Britton & Taylor.)

small and delicate plants. In the largest species of Lygo-
cliuiii the slender twining fronds may reach a great length. Ac-
cording to Hooker (2), the New Zealand species L. articu-
latiun, may reach a length of 50 — 100 feet.

The Gauictophytc

According to Bauke (2), the prothallium in Lygodium,
Aneimia, and Mohria is much like that of the Polypodiaceae,
except that in tlie two latter genera (Fig. 222), the growing
point is at one side. Tlie spores are tetrahedral, and contain
no chlorophyll until after germination has begun. The germ-

THE HOMOSPOROUS LEPTOSFORANGIAT^

385

ination is like that of the Polypodiaceae, and a filament is first
formed, after which the flat prothallium grows for a time by
a single apical cell, which is finally replaced by a group of mar-
ginal cells. In Aiicimia and Mohria the growing point lies on
one side, so that the prothallium is not heart-shaped. In L3;-
godiuin, however, the prothallium has the ordinary form.

The development of the antheridia has been studied by Kny
(4) in Aneimia Jiirta. The only difference between this and

Fig. 223. — Aneimia hirsuta. A, Section of the rhizome, X30; B, part of the central

region, X300.

the normal antheridium of the Polypodiacese is that in Aneimia
the first wall is always flat instead of funnel-shaped, and the
basal cell of the antheridium is therefore disc-shaped. The
archegonia appear to correspond exactly with those of the Poly-
podiacese.

The genus Schiscea, to judge from wS'. pnsilla (Britton and
Taylor (i)), and 6^. dichotoma (Thomas (i)), differs mark-

386

MOSSES AND FERNS

CHAP.

edly from the other genera in the form of the prothalHum,
which is filamentous and extensively branched, resembling very
closely that of certain species of Triclwmanes (Fig. 222, B, C).
The antheridia resemble those of Anciinia, but the archegonium
has the straight neck found in the lower Leptosporangiatre.

The Sporophyte

The tissues of the sporophyte in Lygodinni and Schhcca are
much like those of Glcichenia and the Hymenophyllace?e. As
in these the stem as well as the petiole is traversed by a single

Fig. 224. — Lygodium Japonicum. A, Pinnule, X3; s, the sporangial segments; B,
horizontal section of one of the latter showing the sporangia, sp, X14; C, a single
sporangium, showing the terminal annulus (r), X65; cross-section of the petiole,
X65.

concentric vascular bundle. In most species of Aneimia and
Mohria the bundles of the stem form a cylindrical network like
that of the Polypodiacese. The stem bundles are concentric,
as are those of the petiole and larger veins in all but Schizcca,
which Prantl ( (5), p. 23) states has collateral bundles through-
out, except in the stem. The small veins have collateral bun-

THE HOMOSPOROUS LEPTOSPORANGIATJE

387

dies as in other Ferns. Sclerenchyma is largely developed,
especially in the petioles, where the whole mass of ground tissue
in Lygodium (Fig. 224) is composed of this tissue.

In one section of Aneimia the stele (Fig. 223) has the form
of a continuous tube with both external and internal phloem
and endodermis (see also Boodle (2)).

The leaves are pinnate in all the forms except a few species
of Schizcca. Lygodium, as is well known, shows a continuous
growth at the apex of the leaf, something like Gleichenia, but
here the primary apex retains its meristematic condition, and
the extremely long and slender axis of the leaf twines about its
support like the stem of many climbing plants. The sporo-

FiG. 225. — Aneimia hirsnta. A, Sporophyll, showing the two fertile pinnse, sp.; B,
segment of the fertile pinna, enlarged; C, D, sporangia, X about 40.

phylls are usually smaller than the sterile leaves, or where only
portions of the leaf are sporiferous these are much contracted.
The anatomy of the leaf corresponds closely with that of the
other Ferns. The stomata, which are for the most part con-
fined to the lower side of the leaf, are always arranged in two
parallel row^s in Schizcca, and the peculiar stomata of Aneimia
have already been mentioned. The trichomes are for the most
part hairs. Only in Mohria do scales occur.

In Schizcca pusilla the sterile leaves are filiform, without

388

MOSSES AND FERNS

CHAP.

any distinct lamina. The fertile leaves are pinnately divided.
In other species, e. g., S. dichotoma, the leaves are dichoto-
mously divided, but the fertile leaf-segments are pinnate, as they
are in 6^. pusilla (Diels ( i ) ).

In Anehnia (Fig. 225) the two lower pinncX of the sporo-
phyll are fertile, and in most species become very Ic^ng-stalked
and more divided than the sterile pinnae. The leaves arise from
the dorsal side of the rhizome and in Lygodiuin, Prantl (5)
states that they form but a single row. He also says that the

Fig. 226. — A, Apex of a young, fertile leaf-segment of Ancimia Phyllitides, X200;

B, transverse section of young fertile leaf-segment of Scliicaca Pcnnula, Xioo;

C, part of a similar section oi a somewhat older leaf, Xioo; sp., young sporangia;
in, indusium. (All figures after ..^rantl.)

roots are always diarch, like the Polypodiace^e, but gives no
further details of their growth or structure.

The Sporangimn

The development of the sporangia has been carefully in-
vestigated by Prantl (5) and in origin and arrangement they
differ decidedly from the other Le|)tosporangiates, Imt approach
most nearly Osinnnda, and among the eusporangiate Ferns

THE HOMOSPOROUS LEPTOSPORANGIAT^

389

show a certain likeness to Botrycliiuui. The sporangia arise
always in acropetal order from the apex of the terminal seg-
ments (sorophore) of the sporophyll, and are strictly lateral in
origin, not originating from epidermal cells, but from marginal
ones. The young sporangium appears as a lateral outgrowth
of the margin, exactly like a young pinna upon the main axis,
and the young sorophore has the appearance of a young pinnate
leaf, and at this stage recalls strongly the similar one in Bo-
trychiiim. This is especially marked in Aneimia and Lygo-

FiG. 227. — Cibofium Mcnzicsii. A, Pinnule with the sori (s), X3; B, a single sorus
showing the two-valved indusium, X9', C, a single sporangium, X80; r, the
annulus; D, a paraphysis, X80.

dium, less so In Schizcca, where the sporangia are smaller, and
the mother cells project much more strongly. The early divi-
sions correspond closely with those of the Hymenophyllace?e,
and as there the tapetum is massive and two-layered, and the
stalk of the sporangium very short. The wall is derived in

The divisions in the wall are too complicated to be explained without
numerous figures. See Prantl's figures, Plate V.-VIII.

390

MOSSES AND FERNS

CHAP.

major part from the cap cell, which in all the forms becomes
much more developed than in any other Ferns, and from it
alone the apical annulus is derived. In Aiichjiia and Mohria
the tissue of the tip of the leaf adjacent to the sporangia grows
into a continuous indusium, which pushes them under to the
lower side. In Lygodiiiin (Fig. 224) each sporangium very
evidently corresponds to a single lobe of the leaf segment, and
has a vein corresponding to this. The pocket-like indusium
surrounding each sporangium grows up about it much as the
indusium of Trichomanes grows up about the whole sorus.

sp.

Fig. 228. — Alsophila Cooperi. A, section of the stipe, XiVz; B, cross-section of leaflet,
showing the sori, X20; C, open sporangium.

The Cyatheace^

These are all Ferns of large size, some of them Tree-Ferns,
10 metres or more in height. They occur in the tropics of
both hemispheres, and some of them, e. g., Dicksonia antarctica,
are also found in the extra-tropical regions of the southern
hemisphere. They correspond so closely in all respects with
the typical Polypodiacece that, except for the slightly different
annulus, they might be placed in that family. In some forms,

THE HOMOSPOROUS LEPTOSPORANGIAT^

391

e. g., Alsophila contaniinans, the trunk is quite free from roots,
and the leaves fall away, leaving very characteristic scars
marked by the vascular bundles. In others, like Dicksonia ant-
arctica, the whole trunk is covered with a thick mat of roots,
thicker than the trunk itself.

The prothallium is exactly like that of the Polypodiacere,
so far as it has been studied ( Bauke ( i ) ) , except that in some
species of Alsophila there are curious bristle-like hairs upon the
upper surface. In the structure of the antheridia the Cyathe-
aceae are intermediate in character between the Polypodiacese
and the Hymenophyllacese. The characteristic funnel-formed

Fig. 229. — A, Part of a sporophyll of Thyrsopteris elegans, X2; B, section of the
sorus, Xio; C, leaflet, with two sori, of Cyathea, microphylla. (A, B, after
Kunze; C, after Hooker.)

primary wall of the former occurs here, but not until one and
sometimes two preliminary basal cells are cut off, as in Os-
munda or Hymenophylhim. The following divisions corre-
spond exactly with those of the antheridium of the Polypodi-
acese, except that Bauke states that the cap cell, as well as the
upper ring cell, may divide again. The dehiscence is effected
either by the separation of an opercular cell or by the rupture of
the cap cell. The archegonia are like those of the Polypodi-
acese. In Cyathea medullaris Bauke figures a specimen, how-
ever, where the neck canal cell is divided by a membrane (1. c.
PI. IX, Fig. 8).

The first divisions in the embryo correspond with those of
the Polypodiacese, but the further development of the young
sporophyte is not known.

392

MOSSES AND FERNS chap.

The position of the sori is that of the typical Polypodi-
acese, and sometimes a decidedly elevated placenta is present.
The indusium is either cup-shaped {Cyatliea), or bivalve, e. g.,
Cihotium (Fig. 229), In the latter the outer valve fits closely
over the other like the cover of a box. The sporangia which
are either long or short-stalked, although their development
has not been followed, correspond so closely in the mature state
to those of the Polypodiace^e that there is little doubt that their
development is much the same. The annulus is nearly or quite
complete, but above the stomium in Cihotium Mcnzicsii the cells
of the annulus are broader but thinner-walled (Fig. 227, C),
and Atkinson shows much the same appearance in C. Chamissoi.
In the former species the stalk is long and composed of three
rows of cells, as in typical Polypodiace?e. With the sporangia
in this species are also numerous long paraphyses (Fig.
227, D).

The Parkeriace^ (Diels (i), Kny (6))

This family comprises but a single species, Ceratoptcris
thalictroides, a peculiar aquatic Fern of wide distribution in
the tropics. Unlike most Pteridophytes, Ceratopteris is char-
acteristically annual, although by the formation of adventive
buds it may become perennial.

The prothallia are usually dioecious, and the antheridia dif-
fer from those of the typical Polypodiacese in projecting but
little above the surface of the prothallium.

Except for the peculiarities due to its aquatic habit, in which
respect it differs from all other homosporous Ferns, the growth
of the organs and structure of the tissues is similar to those of
the Polypodiaceae, to which family Ceratoptcris is often as-
signed.

The development of the sporangium is essentially like that
of the PolypodiacCcC, but the annulus sometimes shows an in-
complete development, probably correlated with the aquatic
habit of the plant (Hooker (i), p. 174).

The Polypodiace;e

The Polypodiace?e may very aptly l>e compared to the stego-
carpous Bryinece among the Mosses, inasmuch as like that

THE HOMOSPOROUS LEPTOSPORANGIATJE

393

group they give evidence of being the most speciahsed members
of the order to which they belong, and comprise a very large
majority of the species. Most of them agree closely in their
structure, which has been given in detail, and will not be re-

FiG. 230. — A, Pinnule of Asftdium spinulosuvt, showing the sori (s) with kidney-
shaped indusium, X2>^; B, cross-section of a pinna from a young sporophyll of
Onoclea struthiopteris ; s, sorus, X25.

peated here. With very few exceptions the structure of the
prothallium and sexual organs is like that of Onoclea, but one
or two variations may be mentioned. In Vittaria (Britton and
Taylor (2)), is found a type of prothallium recalling that of

Fig. 231. — A, Polypodium falcatum. Pinna with sori, sp; natural size.

aquilina. C, Asplenium filix-foemina, X3'

B, Pteris

Hymenophyllum, both in its large size and extensive branching.
Its earlier stages show the ordinary development, but it later
branches extensively, and, like Hymenophyllum, numerous
groups of archegonia are formed upon one prothallium. Bod-

394

MOSSES AND FERNS

CHAP.

ies resembling the oil bodies of Liverworts are also met with in
this genus. The sexual organs closely resemble those of the
Polypodiaceae, but the antheridia have a well-marked stalk,
something like that found often in the Hymenophyllaceae.
Among the many genera and species aside from these, while
there is extraordinary variety, the differences are all of second-
ary importance, and consist mainly in the form and venation of
the leaves and the position of the sporangia. The leaves range
from the undivided ones of V iff aria or Scolopcndriiun to the

Fig. 22,2. — Platycerium alcicorne. A, Whole plant, much reduced; B, tip of a spo-
rophyll, showing the crowded sporangia. (A, after Coulter; B, after Diels.)

repeatedly divided leaves, usually pinnate, of such forms as
Pfcris aqnilina. In some tropical epiphytic species, such as
Asplcniuin nidus, Plafyccriiini, species of Polypodium, the
leaves are arranged so that they form receptacles for collecting
humus. In the two latter genera these leaves are very much
modified, the two forms of leaves being familiar to all botanists
m the common Plafyccriuin alcicorne, where the closely over-
lapping round basal ones are very highly developed.

X THE HOMOSPOROUS LEPTOSPORANGIAT^ 395

The sporangia may almost completely cover the backs of
the sporophylls, as in Platycerhim (Fig. 232), or more com-
monly form definite sori, which may or may not have an in-
dusium. Where the latter is present, it is either formed by the
margin of the leaf, as in Adiantuin or Ptcris, or it may be a
special scale-like outgrowth of the lower side of the leaf. In
such cases it is a membranaceous covering of characteristic
form. Thus in Aspidhim (Fig. 230, A) it is kidney-shaped,
in Asplenmm elongated, and free only along one side. Where,
as in Onoclea (Fig. 230, B), the margins of the sporophyll are
involute, so as to completely enclose the sori, the indusium is
wanting or very rudimentary.

CHAPTER XI

LEPTOSPORANGIAT.^i IIETEROSPORE.E (HYDROPTERIDES)^

The two very distinct families of heterosporous Leptospo-
rangiatcT have obviously but little to do with each other, but,
both of them being evidently related to the homosporous forms,
they may be placed together for convenience. Each of the two
families contains two genera, which in the Marsiliacese are
closely allied, but in the Salviniace?e not so evidently so,
although possessing many points in common. They are all
aquatic or amphibians plants, and the gametophyte, especially
in the ]\Iarsiliace3e, is extremely reduced.

Salviniace^

The two genera, Sahinia and AzoUa, contain a number of
small floating aquatics which differ very much in the habit of
the sporophyte from any of the other Filicine?e, but in the de-
velopment of the sporangia and the early growth and form of
the leaves show affinities with the lower homosporous Lepto-
sporangiatcT, from some of which they are probably derived.

The fully-developed sporophyte is dorsiventral, and the
leaves are arrane^ed in two dorsal rows in Azolla, four dorsal
and two ventral in Salvinia. The dorsal leaves are broad and
overlap, so that they quite conceal the stem. Roots are devel-
oped in Acolla, but are quite wanting in Sahinia, where they
are replaced physiologically by the dissected ventral leaves
(Fig. 233). The sporophyte branches extensively, and these
lateral shoots readily separate, and in this way the plants multi-
ply with extraordinary rapidity. The sporangia are enclosed
in a globular or oval "sporocarp," which is really an indusium,

'Also known as Rhizocarpeae.

396

LEPTOSPORANGIATM HETEROSPOREM

397

Fig. 233.—Salvinia natans. A, Small plant, X2, seen from above; B, a similar one
from below; w, root-like submerged leaf; C, fragment of a fruiting plant, X2; sp,
sporocarps; D, a macrosporangial (ma) and microsporangial (mi) sporocarp in longi-
tudinal section (slightly magnified); E, male prothallium with the single anther-
idium (an) from the side, Xiooo; F, a similar one seen from above; G. sperrna-
tozoid (Figs. C, D after Luerssen).

398 MOSSES AND FERNS

CHAP.

much like that of some of the Hymenophyllacese and Cyathe-
aceae.

TJw Gametophyte

The first account of the development of the sexual stage
of the Salviniaceae that is in the least degree accurate is Hof-
meister's ( i), who made out some of the most important points
in the development of the female prothallium. Pringsheim's
(i) classic memoir on Salvinia added still more, as well as
Prantl (4) and Arcangeli ( i ), but none of these observers w^ere
able to follow accurately the earliest divisions in the germinat-
ing macrospores. Berggren's (2) account is the only one on
the female prothallium of Azolla, except a paper by the writer,
but Belajeff (4) has given an excellent account of the germina-
tion of the microspores.

The Male Prothallium

The microspores at maturity are embedded firmly in a mass
of hardened protoplasm, which in Salvinia fills the whole spo-
rangium, but in Aizolla is divided into separate masses, "massu-
lae." The wall of the sporangium in Azolla decays and sets these
free in the water, but in Salvinia the wall of the sporangium is
still evident when the germination takes place. In the latter the
young prothallium grows into a short tube, whose basal part is
separated as a large vegetative cell, from whose base later, Bela-
jeff states, a small cell is cut off. The upper cell becomes the
antheridium. In it is first formed in most cases an oblique
wall, which Belajeff states is always followed by another similar
one, which forms a central sterile cell separating the two groups
of sperm cells. This cell, however, did not occur in the speci-
mens studied by me, where the two groups of sperm cells were
usually in immediate contact (Fig. 233, E). From each of the
upper cells peripheral cells are cut off, but they do not com-
pletely enclose the sperm cells, which are in contact with the
outer wall of the antheridium. A cover cell corresponding to
that in the ordinary Fern antheridium is more or less conspicu-
ous. Each of the central cells divides by cross-walls into four,
and there are thus eight sperm cells in the ripe antheridium.
The spermatozoids of Salvinia have about two complete coils.

LEPTOSPORANGIAT^ HETEROSPORE^

399

and a smaller number of cilia than is usually the case in the
Filicineae (Fig. 233, G).

In Aaolla the contents of the ungerminated microspore,
whose wall is thin and smooth, contain but little granular mat-
ter. The first indication of germination is the rupturing of
the exospore along the three radiating ventral ridges, and the
protrusion of a small papilla. This is cut off by a transverse
wall near the top of the spore cavity, and forms at once the
mother cell of the single antheridium (Fig. 234, C). Belajeff

Fig. 234. — A:;olla Uliculoides. A, Massula with enclosed microspores {sp) , X2S0; gl.
glochidia; B-D, development of male prothallium and antheridium, X560; o, oper-
cular cell; E, cross-sections of a ripe antheridium, X750; i, the top; 2, nearly
median section; x, second prothallial cell.

((3)' P- 329) says the next divisions are nearly parallel and
divide the antheridium into three cells, one above the other, and
of these only the middle ones divide further. For some reason,
which is not quite clear from his account, Belajeff does not re-
gard the whole upper cell as an antheridium, but says that the
latter is only formed after five vegetative cells have been cut off.
It seems much more in accordance with the structure found
in the related homosporous Ferns to regard the whole

400 MOSSES AND FERNS chap.

Upper part of the prothallium as the antheridium. In spite of
his statement that the development of the male prothallium has
little in common with the true Filices, his figures of Azolla are
extraordinarily like the simple male prothallia that sometimes
occur among the PolypodiacecX.

In my earlier studies of the male gametophyte, the second
prothallial cell (Fig. 234, x), described by Belajeff, was over-
looked, but subsequeni examination of my preparations showed
that it w^as present.

The subsequent divisions correspond to Belajeff's account.
In the middle cell of the antheridium two nearly vertical walls
are formed, which with the top cell (cover cell) completely
enclose the central one. The cover cell recalls in form and
position the same cell in the antheridium of the Polypodiaceae,
but is formed here previous to the separation of the central cell.
In one of the lateral cells a horizontal wall is formed, so that
the sperm cells are surrounded by five parietal ones. The cen-
tral cell now divides by a median vertical wall, and each of the
daughter cells twice more, so that eight sperm cells are formed,
as in Sah'inia. The prothallium remains embedded in the sub-
stance of the massula, and the spermatozoids probably escape
by the softening of the outer part of the latter. In Salvinia
the prothallia project beyond the sporangium w^all, and are
easilv detached.

The antheridium of the Salviniaceae does not closely re-
semble that of any other group. A::olla differs less from the
homosporous Ferns in this particular, and shows some resem-
blance to the Hymenophyllace^e in the arrangement of the
parietal cells. Occasionally a triangidar opercular cell occurs
in Azolla, which recalls that in Osiminda.

The Female Prothallhim

The macrospores of Azolla filicidoides are borne singly in
the sporangia. The spores only germinate after they have
been set free by the decay of the indusium, the upper part of
which, however, persists as a sort of cap. The decay of the
sporangium wall and indusium exposes the curious tuberculate
epispore, with its filamentous appendages, which serve to hold
the massulae, w^hich are firmly anchored to them by their
peculiar hairs (glochidia) with their hooked tips. This is evi-

XI LEPTOSPORANGIAT^ HETEROSPORE^ 401

dently of advantage in bringing the male and female plants

together.

The macrospores germinate most promptly in the early
autumn, and in California, where this species is abundant, this
is probably the natural time for germination. As the first
stages of germination take place within the completely closed
spore, it is difficult to tell precisely just when it begins. So
nearly as could be determined, the first division may take place
within two or three days, and the whole development be com-
pleted within a week.

A section of the ripe spore, still within the sporangium,
shows its contents to be nearly uniform, and much like that of
hoctes. The nucleus is here at the apex of the spore cavity
and not conspicuous. It is somewhat elongated and stains but
little. No nucleolus can be seen.

The first sign of germination is an increase in the size of
the nucleus, which becomes nearly globular, and a small nucle-
olus becomes evident. At the same time the cytoplasm about
it becomes free from large granules and indicates the position
of the mother cell of the prothallium. This upper part of the
spore cavity is now cut off by a nearly straight transverse wall,
and this small lenticular cell becomes the prothallium. The
granules in its cytoplasm are finer than those in the large basal
cell, and the nucleus stains strongly and shows a large nucleolus.
The nucleus of the lower cell remains in the upper part, and is
much like that of the prothallial cell.

The first division wall in the upper cell is vertical and di-
vides it into two cells of unequal size. In a prothallium having
but three cells, the second w^all was also vertical, but in others it
looked as if it were horizontal, which Prantl ((4), p. 427)
states is the case in Salvinia. From the upper of the cells
formed by the first horizontal wall the first archegonium arises.
If the horizontal wall forms ea^rly, the primary archegonium is
nealy central, but if two vertical walls precede it, its position is
nearer the side opposite the first cell cut off. In the few cases
where successful cross-sections of the very young prothallium
were made, the archegonium mother cell was decidedly tri-
angular, showing that it was formed by three intersecting walls,
as in Isoetes. It divides into an outer and inner cell, the latter,
as in Isoetes, giving rise at once to egg and canal cells, with-
out the formation of a basal cell.
26

402

MOSSES AND FERNS

CHAP.

Up to this point the exospore remains intact ; the central
cell of the archegonium is only separated from the spore cavity
by a single layer of cells, and the young prothallium agrees
closely with Prantl's account of the similar stage of Salvinia
(Fig. 235, A, B). Berggren's figures of A. CaroUniana, at a
stage presumably the same, are too diagrammatic to allow of a
satisfactory comparison.

Shortly after the first division in the archegonium a rapid
increase takes place in the size of all the cells of the prothal-
lium, by which it expands and ruptures the exospore, which
breaks open by three lobes at the top.

d-T-

Fig. 235. — Acolla filiculoides. A, Longitudinal section through the upper part of the
germinating macrospore, X220; b, b, the basal wall of the prothallium; ar, young
archegonium; n, free nuclei; B, similar section of a nearly developed female pro-
thallium, X220; C, D, archegonia, X375; fi, neck canal cell; v, ventral canal cell;
o, egg; E, two transverse sections of a prothallium with the three first archegonia,
X160; F, median section of a macrospore with large prothallium (/r), X65; in,
indusium; sp, remains of sporangium wall; ep, perinium.

The most remarkable difference between Azolla and the
other Hydropterides is the further development of the lower
of the two primary nuclei.^ In AcoIIa it undergoes repeated
divisions, and the resulting nuclei remain embedded in the
protoplasm in close proximity to the lower cells of the pro-

* Recently Coker (i) has observed a fragmentation of the nucleus in
Marsilia.

XI LEPTOSPORANGIATAi HETEROSPORE^ 403

thallium (Fig. 235, A). This nucleated protoplasm is free
from the large albuminous granules in the lower part of the
spore cavity, and in stained sections presents a finely granular
appearance, and is evidently concerned with the elaboration of
the reserve food materials in the large spore cavity. In ex-
ceptional cases indications of the formation of cell walls be-
tween these nuclei were seen, but usually they remained quite
free. Whether a similar state of affairs exists in Salviiiia re-
mains to be seen.

When the first archegonium is ripe, the prothallium is nearly
hemispherical, with the originally convex base strongly concave.
The central cell of the archegonium is separated by one, some-
times two, layers of cells from the spore cavity, and the neck
projects considerably above the surface of the prothallium.
The latter now pushes up between the softened episporic mass
at the top of the spore, and the archegonium is exposed. In
cross-section the prothallium is more or less triangular (Fig.
235, E), with one angle longer than the others. This longer
arm corresponds to the "sterile third" of the prothallium of
Salvinia, and represents the first cell cut off from the prothallium
mother cell.

If the first archegonium is fertilised, no others are formed;
but usually several secondary ones are present. The second
archegonium arises close to the primary one; indeed its cen-
tral cell is generally separated from it only by a single layer of
cells. The third arises near the base of the larger lobe (Fig.
235, E). In case all of these prove abortive, others develop
between them apparently in no definite order, and to the num-
ber of ten or occasionally more. In the older prothallia these
later archegonia are sometimes borne in small groups upon ele-
vations between the older ones.

The neck canal cell of the archegonium is formed much
earlier than Pringsheim describees in Salvinia, and is cut off
from the central cell about the time the first divisions take
place in the cover cell. Each row of the neck has four cells,
as in Salvinia, and the neck canal cell may have its nucleus
divide, as in Isoetes and the homosporous Filicineae. This has
not yet been observed in Salvinia.

In Salvinia (Pringsheim (i), Prantl (4)) the prothallium
is large and develops a good deal of chlorophyll. It has a very
characteristic appearance, and shows the same triangular form

404

MOSSES AND FERNS

CHAP.

that AzoUa does, but from two of the corners long wing-hke
appendages hang down, and the whole prothallium is saddle-
shaped. The side joining the two wings is the front, and the
primary archegonium occupies the highest point, as in A::olla,

f B. C.

Fig. 236.—Acolla HUculoides. Development of the embryo, X350. A, B, C, Young
embryos in median longitudinal section; D, two horizontal sections of a young
embryo; E, three transverse sections of a somewhat older one; x, x' , initial cells
of the cotyledon; F, two longitudinal sections of an advanced embryo; G, hori-
zontal section of an older one, with the rudiments of the second and third leaves;
b, h, basal wall of the embryo; st, stem; U, cotyledon; r, root; h, hairs; x, apical
cell of the stem; L^, L^, second and third leaves.

and the two secondary ones form a line with it parallel to the
forward edge, which develops a meristem and other archegonia
in rows parallel to the first ones, in case these fail to be fer-
tilised.

In Azolla the prothallium has but little power of independ-

XI LEPTOSPORANGIATJE HETEROSPOREJE 405

ent existence, and even when unfertilised develops but little
chlorophyll. No rhizoids occur (this seems to be true of Sal-
vinia also), and the growth only proceeds until the materials
in the spore are exhausted. To judge from Berggren's figures
A. Caroliniana has a larger prothallium but fewer archegonia
than A. HUciiloides.

The Embryo

The fertilised ovum, previous to its first division, elongates
vertically. The basal wall is usually transverse instead of
longitudinal, as in the other Leptosporangiates, although in
exceptional cases it may approach this position in Azolla.
From the epibasal half in the latter arise, as in the other Lep-
tosporangiat?e, the cotyledon and stem apex; from the hypo-
basal, foot and root. The quadrant walls do not always arise
simultaneously, but as soon as they are formed the primary
organs of the embryo are established and are arranged in the
same way as in other Ferns. Berggren asserts that the root
does not develop until later, and is derived from the foot ; but
in sections it is very evident from the first, and corresponds in
position exactly with that of other Leptosporangiates.

In all but the stem quadrant the octant walls are exactly
median, and this may be true of the latter; but in the stem
quadrant the octant wall may make an acute angle with the
quadrant wall, and the larger of the two cells then forms at
once the two-sided apical cell of the stem, and from now on
divides alternately right and left. Where the octant wall is
median, it is probable, although this could not be positively
proved, that the stem apex forms for a short time three sets of
segments instead of two.

In the cotyledon the median octant wall is followed by a
vertical wall in each octant, forming two cells that appear re-
spectively triangular and four-sided. The former have larger
nuclei and divide for a time after the manner of two-sided
apical cells, and perhaps the first division of the leaf quadrant
may be of the nature of a true dichotomy, and these cells are
the apical cells of the two lobes. In the four-sided cell, the
radial and tangential divisions succeed each other with much
regularity. By the growth of the two initials (Fig. 236, E,
X, ,r') the young cotyledon rapidly grows at its lateral margins

4o6 MOSSES AND FERNS chap.

and bends forward so as to enclose the stem apex. At the
same time the upper marginal cells divide rapidly by oblique
walls alternately on the inner and outer sides, so that the coty-
ledon also increases in length, and by this time it is about four
cells thick.

As soon as the apical cell of the stem is established, it grows
very much as in the mature sporophyte. Each segment divides
into a ventral and dorsal half, and each of these into an acro-
scopic and basiscopic portion. In case the stem octants are
equal at first it is not possible to say which is to form the stem
apex, but this is determined by the first division in each cell:
One of them divides by a vertical wall into equal parts and be-
comes the second leaf; the other forms the stem apex. If the
octants are unequal, the smaller one always forms the leaf. At
the base of the cotyledon, between it and the stem, is a group of
short hairs (Fig. 236, F, h).

The primary root of A::olla arises in exactly the same way
as that of the typical homosporous Leptosporangiatee, except
that here the two root octants seem to be always equal in size,
and as practically only one of them forms the root, the other
dividing irregularly and becoming merged in the foot, the root
is more or less decidedly lateral (Fig. 236, E). After one
complete set of lateral segments has been formed, the primary
cap segment is cut off from the outer face, but, unlike the other
Ferns, this is the only one formed. The cap cell divides later
by periclinal walls, so that there are two layers of cells covering
the apical cell, and these are continuous with the epidermis of
the rest of the embryo, and continue to grow at the base, so that
a two-layered sheath is formed about the young root. The
lateral segments are shallow and arranged very symmetrically,
and the divisions correspond to those in the other Ferns.

The divisions in the foot are more regular than is usually
the case, and this is especially noticeable in sections cut parallel
to the quadrant wall (Fig. 236, E). The general arrange-
ment of the cells is quite like that of the cotyledon, but the
divisions are fewer and the cells larger. Corresponding to
the upward growth of the cotyledon, the foot elongates down-
wards beyond the base of the root, which thus ai)pears as a
lateral growth from it, and no doubt led to Berggren's mistake
concerning its origin.

Salz'iiiia in its early stages is much like Azolla, but, accord-

LEPTOSPORANGIATJE HETEROSPORE^

407

ing to Leitgeb,^ the apical cell of the stem is always three-sided
at first, and only later attains its permanent form. The root
remains undeveloped, and no later ones are produced, but the
first divisions in what corresponds to the root quadrant in
Azolla are apparently very similar to those of that plant, and it
would perhaps be more correct to say that the primary root
remains undeveloped rather than to consider it as completely
absent (Dutailly (i)).

The second leaf in the embryo of AzoUa arises practically
from the first segment of the stem apex, and each subsequent
segment also produces a leaf. The early growth in length of

Fig. 237. — AsoUa filiculoides. Nearly median section of the young sporophyte after it
has broken through the prothallium, Xioo; B, an older plant with the macrospore
isp) still attached; m, massulae attached to the base of the macrospore; r, the
primary root, X40.

the primary root is slow, and it does not become conspicuous
until a late stage. The vascular bundles are poorly developed
and arise relatively late. No trace of them can be seen until
the second leaf is well advanced. Their origin and develop-
ment correspond to those in other forms described. The
tracheary tissue is composed entirely of small spiral tracheids.
The second root arises close to the base of the second leaf,
and like all the later ones is of superficial origin. As the coty-
ledon grows, large intercellular spaces form in it, and the young

*Leitgeb, see Schenk's "Handbuch der Botanik," vol. i. p. 216.

4o8

MOSSES AND FERNS

CHAP.

sporophyte breaks away from the spore or carries the latter
with it to the surface of the water. As the embryo breaks
though the episporic appendages at the top of the spore, these
are forced apart and the cap-shaped summit of the indusium is
thrown off. The cotyledon is funnel-shaped, with a cleft on
one side, and completely surrounds the stem apex. The root
is still inconspicuous, and forms only a slight protuberance
upon one side of the foot, which looks like a short cylindrical
stalk (Fig. 237).

Fig. 238. — Salvinia natans. A, Horizontal section of the stem apex, X4S0; L, young
leaf; B, a young leaf, showing the apical cell (x), X450; C, longitudinal section
of a segment of a ventral leaf, X450; D, section of a dorsal leaf; i, lacunae; h,
hair, X22S; E, cross-section of the stem, X50; F, the vascular bundle, X225.

The growth of the first root is limited, and it differs from
the later ones by forming peculiar stiff root-hairs. Tlie later
roots, except the second, do not seem to bear any definite rela-
tion to the succeeding leaves.

A careful examination of the ripe macrosporangium shows
a number of colourless small round bodies occupying the space

XI LEPTOSPORANGIATAL HETEROSPORE^ 409

between its upper wall and the indusium. These are the rest-
ing cells of a Nostoc-like alga — Anahcena AsoIIcb, — which is
always found associated with this plant. At the same time
that the embryo begins to develop, these cells become active, as-
sume the characteristic blue-green colour of the growing plant,
and divide into short filaments that at first look like short Oscil-
laricr. The cells soon become rounded, and heterocysts are
formed. Some of these filaments remain entangled about the
stem apex of the embryo, while others creep into special cav-
ities which are found in all the leaves except the cotyledon, and
here develop into a colony.

The first branch is formed after the plant has develope 1
about eight leaves, but whether its position is constant was net
determined

The Mature Sporophyte

Strasburger (6) has investigated very completely the tissues
of the mature sporophyte of A::olla, and Pringsheim ( i ) has
done the same in Salvinia, so that these points are very satis-
factorily understood.

The growing point of the stem in Azolla (Fig. 240, A) is
curved upward and backward, in Salvinia (Fig. 238, A) it is
nearly horizontal. In both genera there is a two-sided apical
cell from which segments arise right and left. Each segment
divides into a dorsal and ventral cell, and a transverse section
just back of the apex shows four cells arranged like quadrants
of a circle. In Azolla the dorsal cells develop the leaves, the
ventral ones the branches and roots. Each semi-segment is
divided into an acroscopic and basiscopic cell, and these are fur-
ther divided into a dorsal and lateral cell in the upper ones, into
a ventral and lateral one in the lower. The leaves arise from
one of the dorsal cells, which may be either acroscopic or basi-
scopic, but is always constant on the same side of the shoot, so
that the two rows of leaves alternate. The lateral buds, which
do not seem to appear at definite intervals, arise from one of the
upper cells of the ventral segment, and alternate with the leaves
on the same side of the stem.

The mother cell of a leaf is distinguished by its size and
position (Fig. 240, B, III, L), and the first division wall, as in
the cotyledon, divides it into two nearly equal lobes. No trace

410

MOSSES AND FERNS

CHAP.

of an apical cell can be found in the young leaf, and in this
respect, as well as the secondary divisions of the stem segments,
Azolla differs from Salvinia, where for a long time the young
leaves grow, as in most Ferns, by a two-sided apical cell (Fig.
238, B). Each leaf lobe in Azolla is divided into an inner small
cell and an outer larger one, and the latter is then divided by a
radial wall. This formation of alternating tangential and
radial walls is repeated with great regularity, and can be traced

---h

Fig. 239. — AzoUa filiculoides. A, Longitudinal section of a dorsal lobe of the leaf, X
about 40; ti, cavity with colony of Anahcoia; h, unicellular hairs; B, epidermis
with stomata, X150 (after Strasburger) ; C, longitudinal section of young root,
X225; sh, root-sheath.

for a long time. It is not unlike the arrangement of cells fig-
ured by Prantl ( (i), PI. I, Figs. 2, 3) in some of the Hymeno-
phyllacese.

The fully-developed leaves of Azolla are all alike. In A.
fiUculoidcs the two lobes are of nearly equal size, the lower or
ventral one, which is submersed, somewhat larger, but simpler
in structure. The dorsal lobe shows a large cavity near its base
(Fig. 239, A), which opens on the inner side by a small pore.
On the outer side the epidermal cells are produced into short

XI LEPTOSPORANGIAT^ HETEROSPORE^ 4"

papillate hairs, which in some species, c. g., A. Caroliniana, are
two-celled. Stomata of peculiar form (Fig. 239, B) occur on
both outer and inner surfaces. The bulk of the leaf is com-
posed of a sort of palisade parenchyma, and the cavity is partly
encircled by an extremely rudimentary vascular bundle. The
ventral lobe of the leaf is but one cell thick, except in the middle,
where there is a line of lacunar mesophyll, traversed by a
simple vascular bundle.

In Salvinia the leaves are of two kinds. The dorsal ones
are undivided, and traversed by a single vascular bundle. The
mature leaf shows two layers of large air-chambers, separated
only by a single layer of cells, whose w^alls are like those of the
epidermis. From both upper and lower surfaces, but especially
the former, numerous hairs develop. The ventral leaves are re-
peatedly divided, and each segment grows by a definite apical
cell ; the segments are long and root-like, and covered with
numerous long delicate hairs, looking like rhizoids. These sub-
mersed leaves doubtless replace the roots. The leaves in .^67/-
vinia are arranged in alternating whorls of three, correspond-
ing to the nodes, and this arrangement accounts for the six rows
of leaves previously referred to.

The mature stem shows a central concentric vascular bundle
(Fig. 238, E, F), whose tracheary tissue is somewhat more
compact and the tracheae in Azolla than in Salvinia. This is
surrrounded by a definite endodermis and one or two layers of
larger parenchyma cells, and radiating from the latter are plates
of cells separated by large air-spaces, and connecting the central
tissue with the epidermis (Fig. 238, E).

The lateral branches arise in acropetal order, but apparently
not always at equal intervals. Their development is a repetition
of that of the main axis. Like the branches, the roots in Azolla
arise acropetally, and their number is very much less than the
leaves. They arise from superficial cells and follow exactly in
their development the primary root of the embryo. The inner
layer of cells of the sheath, however, in these later roots be-
comes disorganised, and there is a space between this and the
root itself. A single root-cap segment only is formed subse-
quent to the primary one from which the sheath forms, and this
secondary cap segment undergoes division but once by periclinal
walls (Fig. 239, C).

Leavitt (i) found in the older roots of both A. filiciiloides

412

MOSSES AND FERNS chap.

and A. CaroJiniana numerous root-hairs, which arise from defi-
nite cells, evident while the ''epiblema" or superficial layer of the
root is still actively dividing — a condition which also occurs
in many other Pteridophytes. 'The initials for these root-hairs
arise within a belt of actively dividing cells lying immediately

under the inner root-cap, not far from the apex As

the root reaches the limit of its development, the hair-forming
impulse travels downward until the apical cell itself is split into
several parts, each one piliferous." (1. c, p. 416, 417-)

The Sporangia

The sporangia in both genera are contained in a so-called
sporocarp, which is really a highly-developed indusium. These
sporocarps always arise as outgrowths of the leaves, in Salvinia
from the submersed leaves, in AzoUa from the ventral lobes. In
Salvinia several are formed together (Fig. 233, C), in AzoUa
two, except in A. Nilofica, where there are four. Each sporo-
carp represents the indusiate sorus of a homosporous Fern.

In Azolla iilicidoides these sori arise, as Strasburger ( (6),
p. 52) showed, from the ventral lobe of the lowest leaf of a
branch. My own observations in regard to the origin differ
slightly from Strasburger's in one respect. Instead of only a
portion of the ventral lobe going to form the sori, the whole
lobe is devoted to the formation of these, and the involucre
which surrounds them is the reduced dorsal lobe of the leaf, and
not part of the ventral one.

The leaf lobe, as soon as its first median division is complete,
at once begins to form the sporocarps, each half becoming trans-
ferred directly into its initial cell. In this, walls are formed,
cutting off three series of segments (Fig. 240, D). Next a
ring-shaped projection arises about it, and this is the beginning
of the indusium {id) or sporocarp, which bears exactly the
same relation to the young sorus that it does in Trichomanes,
and Salvinia shows the same thing. From this point the two
sorts of sporocarps in Azolla differ. In the macrosporic ones
the apical cell develops directly into the single sporangium; in
the microsporangial sorus the apex of the receptacle, which prob-
ably represents an abortive macrosporangium (Goebel (22), p.
669) forms a columella from whose base the microsporangia
develop. (Fig. 241, A.)

LEPTOSPORANGIAT^ HETEROSPORE^

413

Fig, 240. — Asolla Uliculoides. A, Vertical longitudinal section of the stem apex, X600;
r, mother cell of a root; B, three successive transverse sections just back of the
apex; m, the median wall; L, mother cell of a leaf, X600; C, single lobe of a
young sterile leaf, X600; D, fertile leaf segments with two very young sporocarp
rudiments, X600; E, longitudinal section of young macrosporangium, showing the
young indusium (tW), X600; t, first tapetal cell; F, older macrosporangium com-
pletely surrounded by the indusium, X35o; n. Anab<rna filaments.

414 MOSSES AND FERNS chap.

The development of the sporangium follows closely that of
the other Leptosporangiat?e up to the final development of the
spores. The tapetum is composed of but a single layer of cells
in AzoUa, but in Sak'inia it usually becomes double (Juranyi
( I ) ) . In both genera the wall remains single-layered, and no
trace of an annulus can be detected.

In the macrosporangium of Azolla the archesporium pro-
duces eight sporogenous cells, the microsporangium sixteen.
In Sak'inia, according to Juranyi, both sporangia contain six-
teen spore mother cells. ^ Shortly after the divisions are com-
pleted in the central cell and tapetum the cell walls of the latter
are dissolved, but for a time the sporogenous cells remain to-
gether. Finally, they become isolated and round off before the
final division into the young spores takes place. In the macro-
sporangium only one spore finally develops. This is at first,
in AzoUa, a thin-walled oval cell lying free in the enlarged cavity
of the sporangium. Examination shows it to be surrounded by
a thick layer of densely granular nucleated protoplasm derived
from the tapetum. As the spore grows the surrounding proto-
plasm and the abortive spores are used by it as it develops, and
through their agency the curious episporic appendages of the
ripe spore are deposited upon the outside. The spore itself is
perfectly globular and surrounded by a firm yellowish exospore,
which in section is almost perfectly homogeneous. The epi-
spore covering this shows over most of the spore a series of
thick cylindrical papillae, from the top of which numerous fine
thread-like filaments extend. In section the epispore shows two
distinct parts, a central spongy-looking mass and an outer more
homogeneous part covering all but the tops of the papillae. At
the top of the spore are three episporic masses, composed entirely
of the spongy substance and surrounding a central conical mass
from whose summit extend numerous fine filaments like those
growing from the rest of the epispore. The name ''swimming
apparatus," which has been applied to this apical mass, is a mis-
nomer, as the ripe sporangium sinks promptly when freed from
the plant.

The indusium rapidly grows above the young macrospo-
rangium, or group of miscrosporangia, and its walls, which be-
come double, converge at the top and finally the opening is com-

' Heinricher (2), however, states that in the macrospangium there are
but eight, as in Azolla.

LEPTOSPORANGIAT^ HETEROSPORE^

415

pletely closed. In the former, before this happens, filaments of
Anahccna creep in and enter the resting condition. Thus they
remain until growth is resumed with the germination of the
spore, when the embryo is infected. The upper cells of the
indusium become very dark-coloured and hard, and remain after
the lower part decays. The wall of the macrosporangium does

Fig. 241. — A, Young microsporangial sorus of A. Uliculoides, X8o; col, columella; id,
indusium; B, nearly ripe microsporangium, X225.

not become absorbed, as Strasburger ((6), p. 71) states, but
remains intact, though very much compressed, until the spore

is ripe.

The sporocarps of Salvmia are like those of A::olla, but the
two layers of cells are separated by a series of longitudinal air-
spaces which correspond to ridges upon the surface of the sporo-
carp (Fig. 233, D).

The microsporangia of A::oUa have a long stalk, which is
composed of usually two, but, sometimes three rows of cells.
The sixteen sporogenous cells all develop, so that there are
normally sixty-four microspores in each sporangium. These
have the exospore thin and smooth, and are included in a kind
of common epispore, which here too owes its origin mainly to
the tapetal cells. This episporic substance is divided into
n-asses (massulae), which have the foamy structure of the
episporic apendages of the macrospore. This appearance is
apparently cue to the formation of vacuoles, which make these

4i6

MOSSES AND FERNS

CHAP.

Sp.

Fig. 242.—Azolla Mculoides. A, Mature sporophyte, X2; B, lower surface of a branch
with two microsporangial sori (,sp), X6; C, macrosporangial (ma) and microspo-
rangial (mi) sori, Xio.

LEPTOSPORANGIAT^ HETEROSPOREM

417

massulae look as if composed of cells. The tapetal nuclei are
confined to the outside of the massulae, and can be detected al-
most up to the time they are fully developed. Finally, upon
the outside of the massulse are formed the curious anchor-like
"glochidia" (Fig. 234, gl) , whose flattened form is due to their
formation in the narrow spaces between the massulae.

In Salvinia the microsporangia arise as branches from spo-
rangiophores which bud out from the columella, so that their
number much exceeds that of the macrosporangia, or of the
microsporangia of Azolla. There are no separate massulae.

Fig. 243. — Marsilia vestita. A, Fruiting plant of the natural size; sp, sporocarps; B,
a single sporocarp, X4; C, cross-section of the same, Xs; D, germinating sporo-
carp, showing the gelatinous ring by whkh the sori (s) are carried out, X3.

and in the macrosporangium the epispore is much less developed
than in Azolla.

The MarsiliacetE

The two genera of the Marsiliaceae, Marsilia and Pihdaria,

are much more closely related than Salvinia and Azolla, and at

the same time their resemblance to the homosporous Ferns is
27

4i8 MOSSES AND FERNS chap.

closer, and of the two genera Pilularia is evidently the nearer
to the latter. The development of both gametophyte and
sporophyte in the two corresponds very closely.

The sporangia are borne in ''sporocarps," which are mor-
phologically very different from those of the Salviniacese, be-
ing metamorphosed leaf segments enclosing several sori, and
not single sori enclosed simply in an indusium. The spores
germinate with extraordinary rapidity, especially in Marsilia,
and in M. Aigyptiaca the writer has found a two-celled embryo
developed within thirteen hours from the time the ungermi-
nated spores were placed in water.

The sporocarp of Marsilia is a bean-shaped body, which is
attached to the petiole of the leaf by a more or less prominent
pedicel. It is very hard, and unless opened artificially may
remain a long time unchanged, if placed in water ; but if a little
of the hard shell is cut away, the swelling of the interior muci-
laginous tissue quickly forces apart the two halves of the fruit.
As more water is absorbed, this gelatinous inner tissue con-
tinues to expand and forms a long worm-shaped body (Fig.
243, D), to wdiich are attached a number of sori, each sur-
rounded by a sac-shaped indusium in which the sporangia are
closely packed. IMacrosporangia and microsporangia occur in
the same sorus. The former contain a single large oval white
spore, the latter much more numerous small globular ones.
The indusium remains intact for several hours, if not injured,
but finally, with the sporangium wall, is completely dissolved,
and the spores are set free.

The Microspores and Male Prothalliiim

The microspores of M. vcstita (Fig. 244) are globular cells
about .075 mm. in diameter. The outer wall is colourless and
sufficiently transparent to allow the contents to be dimly seen.
Lying close to the wall are numerous distinct starch granules,
and in the centre the nucleus is vaguely discernible. Sections
through the ungerminated spore show that the wall is thick,
with an inner cellulose endospore, outside of which are the
exospore and the epispore or perinium, composed of closely-
set prismatic rods. The central nucleus is large and distinct,
with usually one or two nucleoli.

The first division takes place at ordinary temperatures.

LEPTOSPORANGIAT^ HETEROSPOREM

419

about 20° C, within about an hour after the spores are placed
in water. Previous to this the nucleus enlarges and moves to
one side of the spore, usually the point opposite the apex, and
the granular cytoplasm collects near the centre and is connected
with the peripheral cytoplasmic zone only by thin strands.
The first wall divides the spore into two very unequal cells, the

Fig. 244. — Marsilia vestita. Germination of the microspores, X450; x, vegetative pro-
thallial cell; m, basal antheridial cell; p, peripheral antheridial cells; A, an unger-
minated spore, ventral aspect; B, section of a similar one — all longitudinal sections
except E and F, which are transverse. In these the two groups of sperm cells are
separated by a large sterile cell.

smaller containing but little granular contents, and representing
the vegetative part of the prothallium, while the upper becomes
the antheridium. In Pilularia there is subsequently cut off a
small cell from the vegetative cell, and BelajefT (4) states that
this also is always the case in Marsilia, but it is less conspicuous

420

MOSSES AND FERNS

CHAP.

than in Pilularia (Fig. 245, A, y). The next division is not
always the same, but is usually effected by a wall nearly parallel
to the first one, but more or less concave (Fig. 244, D). Some-
times the antheridial cell divides at once by an oblique wall into
two nearly equal cells, from each of which a group of sperm
cells is later cut off. In no case was the central cell cut off by
a dome-shaped wall, such as is common in the homosporous
Ferns, and also in Pilularia. The formation of this wall is
apparently suppressed here, perhaps as the result of the ex-
tremely rapid development of the antheridium, and the separa-
tion of the sperm cells takes place by walls cut off from the
periphery of the two upper cells. A cap cell (Fig. 245, d) is
almost always present, as in Pilularia and the Polypodiacese.

From the two cells of
the middle part of the
antheridium a varying
number of sterile cells are
cut off, which are quite
transparent, while the
contents of the central
cells are very densely
granular. Not infrequent-
ly the two groups of
sperm cells are completely
separated by one of these
sterile cells (Fig. 244, F),

Fig. .45.-Marsnia vcstita. A, Longitudinal, B, ^nd Bclajcff COUSiderS

transverse division of the male gametophyte, that Cacll grOUp of SpCmi

X400; X, y, the two vegetative prothallial 11 rpnrPQPntQ n dktinrt

cells; C. two free spermatozoids, X800; v, ^CllS 1 eprCSeUtS d. CUStmCt

vesicle. anthcridium. In view of

the relationship between
the Marsiliacese and Schiza^acese, indicated by recent studies
on the structure and development of the two families (Camp-
bell (26)), this view has some support, as there is a cer-
tain resemblance between each of these cell groups and the
simple antheridium of Ancimia or Schizcca. The divisions in
the central cells are very regular, and the sixteen sperm cells in
each group are arranged very symmetrically (Fig. 245). The
whole number in M. vcstita is completed in about seven hours
from the time germination begins, and the formation of the
spermatozoids commences about an hour later and takes about

XI LEPTOSPORANGIAT^ HETEROSPOREJE 421

four hours for its completion. Piliilaria approaches much nearer
to the Polypodiaceae in the structure of the antheridium (Fig,
246). The first funnel-shaped wall is much more frequently
extended to the basal wall, and the two groups of sperm cells
are much less distinct than in Marsilia.

The spermatozoids of Marsilia are at once distinguished
by a great number of coils, sometimes thirteen or fourteen in
M. vestita. The cilia are very numerous, but are attached only
to the broad lower coils, the upper narrow ones being quite free
from them. The vesicle attached to the broad lower coils is
very conspicuous and contains numerous starch granules as
well as albuminous ones. In Pilularia the long upper part of
the spermatozoid is absent, and it apparently corresponds only
to the few broad basal coils of that of Marsilia, which are of
nuclear origin, like the
greater part of the body
in the spermatozoid of
Pilularia.

Shaw (3) and Belajeff
(7) have studied the de-
velopment of the sperma- ^^^^

tozoid in Marsilia, Shaw'sx-— \r J^^^;^^ /

studies on M. vestita be- ^^^^ ,^e.-R\^e antheridium of Pilularia globuli-

ing especially complete. fera, showing the two vegetative prothallial

At ihf- pInQf- nf thp QPr- ^^^^ (-^' ^>' X375; B, free spermatozoid,

At tne Close 01 tne^ sec showing the large vesicle {v) with the con-

Ond from the last division tained starch granules.

of the central tissue of the

antheridium, there appears at either pole of the spindle a small
body, the "blepharoplastoid," which seems later to divide, the
two halves increasing in size and remaining together near the
resting nucleus. These two blepharoplastoids seem to disap-
pear during the early stages of the next mitosis, but shortly
afterwards there is seen at either pole of the spindle a small
blepharoplast {h). At the close of the mitosis the blepharo-
plast lies near the nucleus of the cell (the secondary sperma-
tocyte of Shaw) . This blepharoplast divides, and the daughter
blepharoplasts increase in size, finally occupying a position near
the poles of the nuclear spindle (Fig. 247, B). This division
results in the formation of the spermatozoid mother cells, or
spermatids.

After the division into the spermatids is complete, the

422

MOSSES AND FERNS

CHAP.

blepharoplast increases in size, and shows several granular
bodies within it, and it is from these granules that the cilia-
bearing band is developed.

The blei^^iaroplast becomes much elongated and with the
nucleus moves toward one side of the sperm cell (Fig. 247, D).
The nucleus also elongates, but the l)lepharoplast extends far
beyond it. The blepharoplast finally forms a funnel-shaped
coil of ten or more turns, of which the three posterior coils,
which are much wider, are in contact with the slender coiled
nucleus, which does not extend beyond this point (Fig. 247, E).

The Macrospore and Female ProthalUnm

The macrospores of the Marsiliace?e are extremely complex
in structure, and are borne singly in the sporangia. In Mar-

FiG. 247. — Marsilia restita. Development of the spermatozoid, Xisoo- A-C, lasi
division preliminary to the formation of the spermatids; D-F, development of the
spermatozoid; n, nucleus of spermatid; h, blepharoplast (after Shaw).

sUia vestifa they are ellipsoidal cells about .425X750 mm- ^
diameter, ivory-white in colour, and covered with a shiny muci-
laginous coating. The upper part of the spore has a hemi-
spherical protuberance covered with a brown membrane, and
it is the protoplasm within this papilla that forms the prothal-
lium. The apex of the papilla shows the three radiating ridges
like those in the microspores, and indicates that, like them, the
macrospore is of the radial or tetrahedral type.

Sections of the ungerminated spore (Fig. 248, A) show a
structure much like that of the microspore, but more highly

LEPTOSPORANGIAT^ HETEROSPORE^

423

developed. A noticeable difference is the segregation of the
protoplasm containing the nucleus, which occupies the apical
papilla. This is filled with fine granules, but is entirely free
from the very large starch grains of the large basal part of the
spore. The nucleus is somewhat flattened. A similar arrange-
ment of the spore contents is found in Pilularia, but the apex
of the spore does not form a distinct papilla. The epispore is
of nearly equal thickness, except at the extreme apex, in Mar-
silia, but in Pilularia, especially in P. globulifcra, the epispore

Fig. 248. — Marsilia vestita. Germination of the macrospore; A, longitudinal section of
the ripe macrospore, X6o; n, nucleus; B-G, successive stages in the development of
the female prothallium and archegonium, X360; C, E, transverse sections, the
others longitudinal; n, neck canal cell; h, ventral canal cell; r, receptive spot of
the egg; k, remains of the nucleus of the spore cavity.

of the upper third is much thicker, and from the outside the
spore appears somewhat constricted below this.

Previous to the first division, w^hich in M. vestita takes
place about two hours after the spores are placed in water, the
amount of protoplasm at the apex increases, and the nucleus
becomes nearly globular and there is an increase in the amount
of chromatin. In Pilularia the first wall is always transverse
and cuts off the mother cell of the prothallium; but in Mar-
silia, while this is usually so, occasionally a lateral cell is cut

424

MOSSES AND FERNS

CHAP.

off first from the papilla. In Pilularia the next wall is parallel
to this transverse primary wall, and this may also occur in
Marsilia, but in the latter more commonly the first lateral cell
is first cut off by a vertical wall, and this is followed by two
others, which intersect it and include a large central cell (Fig.
248, E), from which a basal cell is subsequently separated. In
Pilularia, besides the formation of the basal cell by the second
wall, the central cell is, as a rule, cut out by two, and not three,
walls. The basal cell of the archegonium in Marsilia divides

by cross-walls into equal quad-
rants, and the lateral cells divide
both by vertical and horizontal
walls before any further divi-
sions take place in the arche-
gonium. This finally divides
into the cover cell and inner cell.
The neck is very short, especially
in Marsilia, and each row has but
two cells. These in Pilularia
(Fig. 249) are much longer.
Both neck and ventral canal cells
are very small, especially in Mar-
silia, and the former has its nu-
cleus undivided. In Marsilia
the prothallium grows gradually
as the divisions proceed, but in
Pilularia (Fig. 249) the young
prothallium increases but little in
size until the divisions are almost
Fig. 249.-Piiuiaria giobuiifera A. B. completed, whcu there is a sud-

Young female prothalha, longitu- ^

dinai section, X300; c, neck canal dcii enlargement. The complete

cell; C, section of a recently fer- development of the prothallium

tilised archegonium, X300; sp, / '^

spermatozoid within the egg. OCCUplCS about tWClve tO fifteen

hours in Marsilia vest it a, and in
Pilularia giobuiifera forty to forty-five hours.

Coker ( i ) states that in Marsilia Drummondii the nucleus
in the basal part of the spore subsequently becomes very large
and irregular in form and finally divides amitotically in several
parts which apparently remain active for some time.

The Qgg in both genera is large, but in Marsilia it is the
larger. In both, the receptive spot is evident. The nucleus

LEPTOSPORANGIATJE HETEROSPORE^

42s

IS unusually small in Marsilia, which otherwise resembles

Pihdaria.

The phenomena of fecundation are very striking in the
Marsiliace^. The mucilaginous layer about the macrospore
attracts and retains the spermatozoids, which collect by hun-
dreds about it. The mucilage above the archegonium forms

Fig. 250.— Mam/to vestita. Development of the embryo. A, Longitudinal section of
archegonium with two-celled embryo; B, similar section of a later stage; C, two
transverse sections of a young embryo; D, two longitudinal sections of an older
one; I, I, the basal wall; L, cotyledon; st, stem; r, root; F, foot. A-C, XS25;
D, X260.

a deep funnel, which becomes completely filled with the sperma-
tozoids. As these die their bodies become much stretched out,
so that they look very different from the active ones, with their
closely placed coils. The attractive substance here is not con-
fined to the material sent out from the open archegonium, as th^

426 MOSSES AND FERNS chap.

spermatozoids collect in equal numbers about those which are
still closed, and even about spores that have not germinated
at all. Marsilia did not prove a good subject for studying the
behaviour of the spermatozoid \vithin the egg, owing to the
difficulty of dififerentiating the spermatozoid after its entrance.
Pilnlaria is better in this respect, and shows that the changes
are the same as those described in Marattia and Osuiunda.

Coincident with the first divisions in the embryo, each of
the lateral cells of the prothallium (venter) divides by a peri-
clinal wall, but the basal layer of cells remains but one cell thick.
The prothallium grows with the embryo for some time, and in
its later stages develops abundant chlorophyll, and its basal
superficial cells grow out into colourless rhizoids. In case the
archegonium is not fertilised, the prothallium grows for a long
time, and reaches considerable size, but never develops any
secondary archegonia. In Pilnlaria, both prothallium and em-
bryo may develop chlorophyll in perfect darkness (Arcangeli

(0,p. 336).

The Embryo {Hanstein (2) ; Campbell (j, 13))

The two genera correspond very closely in the development
of the embryo, which shows the greatest resemblance to the
Polypodiacese. In Marsilia the development of the embryo
proceeds very rapidly. The first division of the tgg is com-
pleted within about an hour after the spermatozoid enters, and
in Pilnlaria after about three hours, as nearly as could be made
out. In both the basal wall is vertical and divides the some-
what flattened egg exactly as in Onoclea. The quadrant walls
next follow, and then the octant wall, as usual. Of the latter
the one in the root quadrant diverges very strongly from the
median line (Fig. 250, C), and that in the foot quadrant is
much like it. In the others it is nearly or quite median, and it
is impossible to say which of the leaf and stem octants is to
form the apical cell of those organs. The relative position of
the young organs is exactly the same, both with reference to
each other and to the archegonium, as in the Polypodiaceae.

The Cotyledon

The cotyledon grows for a time from the regular divisions
of one or both of the primary octant cells, but this does not

LEPTOSPORANGIAT^ HETEROSPORE^

427

usually continue long, and the subsequent growth is purely
basal. The cotyledon is alike in both genera, and is a slender
cylindrical leaf tapering to a fine point, where the cells are much
elongated and almost colourless. Its growth is at first slow,
but at a later period (in Pihilaria globulifera about the eighth
day) it begins to grow with great rapidity and soon reaches its
full size. This is largely due to a simple elongation and ex-
pansion of the cells, which are separated in places, and form a
series of longitudinal air-channels separated by radiating plates
of tissue (Fig. 251, i). The simple vascular bundle traversing

Fig. 251. — Longitudinal section of the young sporophyte of Pilularia globulifera, still
enclosed in the calyptra {cat), and attached to the macrospore {sp), X75; B, the
lower part of the same embryo, X21S; r, apical cell of the root; st, apical cell of
the stem; i, lacunae.

the axis is concentric, with a definite endodermis, but the
tracheary tissue is very slightly developed. This becomes first
visible about the time the leaf breaks through the calyptra.

The Stem

Of the two octants in the stem quadrant one becomes at
once the apical cell of the stem, the other the second leaf, as in
other Leptosporangiatae. The first wall in each octant meets
octant and quadrant walls, and cuts off a large cell from each

428 MOSSES AND FERNS chap.

octant, in contact with the foot. Hanstein and ArcangeH re-
gard these as part of the foot, and physiologically they no doubt
are to be so considered, but morphologically they are beyond
question segments respectively of the stem and second leaf. At
first these are not distinguishable from each other, but the divi-
sions in the latter are usually (in Pihdaria) less regular, and
the apical cell early lost. It may, however, develop a regular
three-sided apical cell, like that of the later leaves. The earlier
segments of the stem apex are larger than the subsequent ones,
and the broadly tetrahedral form of the primary octant is re-
duced to the much narrower form found in the older sporophyte.

The Root

The first wall in the root quadrant strikes the basal wall
at an angle of about 60°, so that the octants are of very unequal
size (Fig. 250, C), and the larger one, as in other similar cases,
becomes at once the initial cell of the root, which in both genera
shows the same regular divisions that characterise the Poly-
podiaceae. The segments of the root-cap do not form any peri-
clinal walls, and remain single-layered. The root, like the
cotyledon, is traversed by regular air-chambers, and its trans-
verse section resembles very closely that of the leaf. These air-
chambers appear while the root is very young, and at a point
between the endodermis and the cortex. The latter is at this
stage divided into but two cells, the outermost of which by a
further tangential division becomes two-layered, the outer
forming the epidermis, and the inner by similar divisions be-
comes three-layered. The two outer layers divide by radial
walls, but the inner ones divide only by periclinal walls, and
form one-layered lamellae separating the air-spaces and connect-
ing the endodermis with the outer cortex.

The Foot

The first divisions in the foot quadrant follow closely those
in the root, but this regularity soon ceases, and after the first
divisions no definite succession in the walls can be distinguished.
The foot remains small, but, as we have seen, the first segments
of the lower epibasal octants practically form part of it, and
doubtless all the lower cells are concerned in the absorption of

XI LEPTOSPORANGIAT^ HETEROSPORE^ 429

food from the spore. The vokime of the protoplasm in the
spore increases as the prothalhum grows, but loses more and
more its coarsely granular structure. In both Marsilia and
Pilularia the nucleus of the spore cavity soon becomes indis-
tinguishable, and in the former is from the first very small. In
Pilularia it is larger, and in the later stages bodies were ob-
served that looked as if they might be secondary "endosperm-
nuclei," like those of Azolla, but their nature was doubtful. A
further study of Marsilia vestita has shown irregular deeply
staining bodies in the protoplasm below the basal prothallial
cells, which may perhaps be nuclei like those described by Coker
( T ) in M. Drummondii.

The early leaves are at first alike in both genera, and the
earliest ones do not show any trace of the circinate vernation of
the later ones. In Pilularia the later leaves are essentially like
the cotyledon, but in Marsilia all the later leaves show a distinct
lamina. This is at first narrow and undivided, and spatulate
in form. In M. vestita this is succeeded by five or six similar
ones, with constantly broadening laminae, which finally divide
into two narrow wedge-shaped lobes, and these are then suc-
ceeded by others with broader lobes, which finally are replaced
by four lobes, the central ones being narrower than the outer
ones. All of these early lobed leaves are folded flat, and it is
not until about ten or twelve leaves have been formed that
finally the leaf attains the form and vernation of the fully-devel-
oped ones.

The divisions in the stem apex take place slowly, but appar-
ently a complete series of segments is produced in rapid succes-
sion, and there is an interval before any more divisions occur,
as there is always considerable difference in the ages of any
two succeeding sets of segments. The apical cell of Pilularia
in cross-section has the form of an isosceles triangle with the
shorter face below. Probably^ each dorsal segment at first
gives rise to a leaf, and each ventral one to a root. However,
the number of roots exceeds that of the leaves, but the origin
of these secondary roots was not further investigated.

The Mature Sporophyte

In both Marsilia and Pilularia the fully-developed sporo-
phyte is a creeping slender rhizome, showing distinct nodes and

430

MOSSES AND FERNS

CHAP.

Etc. 252. — Part of a fruiting plant of Ptlularia Americana, X4; sp, sporocarpa

LEPTOSPORANGIAT^ HETEROSPOREJE

431

internodes. At the nodes are borne the various appendages of
the stem, and the elongated internodes are, except for occa-
sional roots, quite destitute of appendages. Leaves and
branches arise from the nodes, and in Marsilia are much
crowded. The plants are aquatic or amphibious, and the habit
of the plant is very different, especially in Marsilia, as it grows
completely submerged, or partially or entirely out of water.
Some species, like M. vcstita, which grow where there is a

Fig. 253. — Marsilia vestita. A, Vertical longitudinal section of the stem apex, X8o;
L, leaves; st, stem apex; r, roots; B, the stem apex, X450; C, horizontal section of
very young leaf, X450; D, similar section of an older one, X4S0; E, cross-section
of petiole, X8o.

marked dry season, grow in shallow ponds or pools, which dry
up as the end of the growing period approaches, and the ripen-
ing of the sporocarps takes place after the water has evaporated.
In the first case the petioles are extremely long and weak, and
the leaf-segments float upon the surface. In the other case the
petioles are much shorter and stouter, and the leaves are borne
upright. The young leaves are circinate, as in the ordinary
Ferns, and in Pihilaria retain the same structure as the coty-

432 MOSSES AND FERNS chap.

ledon. In Marsilia they are always four-lobed. The sporo-
carps are modified outgrowths of the petiole, which are often
formed so near the base as to appear to grow directly from the
stem. They often are borne singly, but may occur in consider-
able numbers — twenty or more in M. polycarpa — and are glob-
ular in Pilularia, bean-shaped in Marsilia. The growth of the
stem and the origin of the various appendages are the same in
both genera.

A longitudinal section of the stem (Fig. 253, A) shows the
decidedly pointed apex occupied by a large and deep apical
cell with very regular segmentation. Each segment divides
into an inner and an outer cell, the former in all the segments
forming the central plerome cylinder, and the outer cells devel-
oping the cortex of the stem, and the leaves in the dorsal seg-
ments, the roots in the ventral ones. The young leaves are
separated by distinct intervals or internodes, and apparently
all of the dorsal segments do not give rise to leaves, but just
what the relation is between the nodes and internodes was not
determined. The roots arise in strictly acropetal order from
the ventral segments, but their number does not seem to be
constant. In Pilularia Americana the number of roots con-
siderably exceeds that of the leaves, as it does in the young
sporophyte of P. globulifera.

The single axial vascular bundle is truly cauline, and ex-
tends considerably beyond the base of the youngest leaf. The
later leaves in Pilularia, lx)th in their growth and complete
structure, correspond to the primary ones. They grow for a
time from a three-sided apical cell, in which respect they differ
from Marsilia} The development of the leaf of the latter has
been carefullv studied bv Hanstein in M. Driimmondii, and M.
vestita corresponds exactly with that species. A section of the
very young leaf (Fig. 253, C) parallel with the surface shows
a large two-sided apical cell. The leaf-rudiment assumes a
somewhat spatulate form, and on either side a projecting lobe
is formed, the rudiment of one of the lateral segments of the
leaf. The apical cell is now divided by a median wall, after
which periclinal walls are formed, and from this time the
growth of the leaf can no longer be traced to a single initial cell.
The first longitudinal wall in the apical cell establishes the two

^Pilularia globulifera, according to Johnson (2) and Meunier (i) has
the typical two-sided cell found in Marsilia.

XI LEPTOSPORANGIAT^ HETEROSPOREM 433

terminal lobes, which at first are not separated (Fig. 253, D).
The establishment of the veins follows exactly as in Ferns with
a similar venation, and is strictly dichotomous. The stem
branches freely in both genera, and the branches arise close to
the apex, and below a young leaf somewhat as in Azolla.

The roots correspond closely to those of the higher
homosporous Ferns. The segmentation of the apical cell fol-
lows the same order as in the Polypodiaceae. Goebel's figure of
M. salvatrix ( ( 10), p. 238) differs somewhat from the account
given more recently by Andrews ( i ) for M. qnach'ifolia. The
latter observer states that there are no periclinal walls in the
root-cap segments, which remain throughout one-layered, and
that the separation of the plerome takes place earlier than Goe-
bel indicates. Van Tieghem's ((5), p. 535) account of the
root of M. DrumiiiGndii confirms Andrews' observations upon
M. quadrifolia. The bundle of the root is diarch, as in the
Polypodiacese, and the lateral roots arise in the same manner.
The endodermal cells from which they spring are distinguished
from the others by their shorter and broader form, and are very
easily recognisable by this as wxll as from their position. They
form two vertical rows exactly opposite the ends of the xylem
plate, and the lateral roots therefore are also strictly tw^o-ranked.
Narrow lacunae are formed in the cortical tissue of the root,
and the cells surrounding these are connected by regular series
of short outgrowths, which connect them in a way that recalls
very strongly the connecting tubes between conjugating fila-
ments of Spirogyra, and produce a similar ladder-like ap-
pearance.

The solid vascular cylinder of the young stem is later usu-
ally replaced by a tubular one, but its structure is also con-
centric, with phloem completely surrounding the xylem, and it
has both an inner and outer endodermis. When the plants are
completely submerged the ground tissue is mainly parenchyma,
but in the terrestrial forms sclerenchyma may be developed in
the cortex of the stem and petiole. The latter is always trav-
ersed by a single axial bundle, which in the lamina in Marsilia
divides repeatedly near the base of the wedge-shaoed leaflets
into numerous dichotomous branches.

Luerssen ((7), p. 601) mentions as special reproductive
bodies, tubers found in M. hirsuta. These are irregular side
branches covered with imperfectly-developed leaves, and with
28

434

MOSSES AND FERNS

CHAP.

the cortical tissue strongly developed and full of starch. These
are supposed to survive long periods of drought, and to germi-
nate under favourable conditions. A condition somewhat
analogous to this appears in M. vestita (Fig. 243, A), but
whether these short lateral branches are of this nature was not
investigated.

The Sporocarp (Sachs (i) ; Gochcl (6) ; Meunier (i) ;

{Johnson (/, 2))

The development of the sporocarp is much the same in the

I ^

/' . \^i -r^ \

coqo

Fig. 254. — Pilularia Americana. Development of the sporocarp. A. \'ery young
sporophyll with sporocarp rudiment (sp), showing a distinct apical cell; B-D,
longitudinal sections of young stages, showing the formation of the "sorus canals"
(sc), X130; z', the original apex of the young sporocarp; L, secondary lobes or
leaflets; E, longitudinal section of an older stage, X about 130; s, s, young sori;
F, transverse section of an older sorus, X 180.

two genera, but is most easily followed in the simple sporocarp
of Pilularia. In P. Americana, the young fruit begins to de-
velop almost as soon as the leaf can be recognised, and while it
is still close to the stem apex. Growth is stronger upon the
back of the young leaf, and it very early assumes the circinatc

XI LEPTOSPORANGIAT^ HETEROSPORE^ 435

form. Before this curvature is very pronounced, however, in
the sporophyll, a protuberance arises upon its inner face, a short
distance above the base (Fig. 254, A). This originates from a
single cell, which functions for some time as an apical cell, and
causes the young sporocarp to project strongly from the leaf, of
which it is simply a branch, somewhat analogous to the spike in
Ophioglossiiju. It may, perhaps, be better compared to a fertile
leaf segment of Ancimia, as it has been shown by Johnson (2),
that the mother cell of the young sporocarp arises from the
margin and not from the face of the leaf.

It has at first the form of a blunt cone, but soon upon the
side turned toward the leaf a slight prominence appears (Fig.
254, B, L) , and about the same time two similar lateral ones are
formed. As in the sterile part of the leaf growth is stronger
on the outside, and the young sporocarp bends in toward the
leaf, so that the position of fertile and sterile segments is very
like that in the young sporophyll of Ophioglossum. The apex
of the sporocarp rudiment, together with the three lobes, en-
close a slightly depressed area, which becomes the top of the
sporocarp. The four prominences (including the original
apex of the fertile segment) are beyond question to be consid-
ered leaflets, which remain confluent except at the top. A little
later a slight depression or pit forms at the base of each lobe
and the central area at the top. These pits are separated later-
ally by the coherent edges of the leaflets, which extend to the
axis of the sporocarp and are continuous with it. As the
young fruit enlarges, the depressions deepen owing to the
elongation of both leaflets and the axial tissue, which forms a
sort of central columella (Fig. 254, D). Thus are formed
four deep cavities, separated laterally by the united margins of
the leaflets, and corresponding to the much more numerous
"canals" described by Russow and Johnson in the fruit of
Marsilia; like these they at first -open at the summit by a pore,
and a study of longitudinal sections shows clearly their strictly
external origin.

From his study of P. glohuUfcra, Johnson (2) concludes
that all four lobes of the sporocarp are of lateral origin. He
was able to trace the origin of each sorus to a single marginal
cell in each of the four segments of the young sporocarp. Sec-
tions of the young sporocarp of Marsilia at this stage (John-
son (i). Figs. 22, 23) resemble to an extraordinary degree

436

MOSSES AND FERNS

CHAP.

the young fertile segment of the leaf of Schizcoa, where the
relation of the sporangia to the leaf margin is very similar.

Up to the time the cavities begin to form, the young fruit
is composed of uniform tissue, but shortly after, the tissue sys-
tems become differentiated, and the peduncle of the sporocarp
is formed. At this time the vascular bundle of the peduncle
can be recognised, and joins that of the sterile segment near

Fig. 255. — Marsilia quadrifolia. A, Horizontal section of very young sporocarp, X500;
B, transverse section of an older sporocarp; s c, sorus canal; sp, young sporan-
gium, X about 340; C, horizontal section of young sorus showing the large apical
macrosporangium, and the lateral microsporangia, mi; in, the indusium. (After
Johnson.)

its base. The peduncle is much longer in P. Americana than
in the very similar P. glohulifera. The circinate coiling of
the sterile segment is repeated, though less conspicuously, here,
and the body of the sporocarp is bent at right angles to the
peduncle.

LEPTOSPORANGIAT^ HETEROSPORE^

437

The cavities rapidly become larger with the expansion of
the growing sporocarp, but the space between the inner surface
of the lobes and the columella remains narrow, owing to the
growth of the sorus, w^iich almost completely fills it from the
first. The sorus forms an elongated cushion, extending nearly
the whole distance from the apex to the base of the lobe, along
the median line of its inner face. In origin and position it
corresponds closely to that of the Schizseacese.

Fig. 256. — Transverse section of an older sporocarp of P. Americana, showing the four
sori (j); jh, vascular bundles, X85; B, section of the wall of a nearly ripe sporo-
carp, X255.

The vascular bundle of the peduncle divides into four
branches, where it enters the sporocarp, and one branch goes
to each lobe, of which it forms the midrib lying below the
sorus. From each of these two smaller branches are given
off near the base, following the margin of the lobe (Fig. 256,

438 MOSSES AND FERNS chap.

A). By this time the outer epidermal cells begin to thicken,
the first indication of the hard shell found in the ripe sporo-
carp.

The development of the sporangia corresponds most nearly
to that of the Schizaeace?e. The surface cells of the sorus pro-
trude as papillcX, in which the same divisions arise as in other
Leptosporangiat?e. The first division wall is usually strongly
oblique, but may be transverse. The formation of the arche-
sporium is the same, but the apical growth of the sporangia is
checked sooner in the earlier ones, which have consequently a
very short stalk. In the later ones, which arise between the
others, the stalk is longer. The first sporangia are formed at
the base of the sorus, and their development proceeds toward
the apex; but later secondary ones may arise at any point in
the sorus.

The tapetum is well developed, and, as in most homospo-
rous Ferns, consists of two layers, in some places of three.
The number of sporogenous cells is usually eight, but some or
all of these may divide again, so that the whole number ranges
from eight to sixteen. The dissolution of the tapetum walls
and subsequent division of the spores follow precisely as in
AzoUa. In stained sections the nucleated protoplasm of the
tapetal cells is very evident after the walls have disappeared.
At this point the difference in the two kinds of sporangia be-
comes manifest. Those in the lower part of the sorus, i. e.,
the oldest ones, form the macrosporangia, the upper ones
microsporangia. In the latter all the spores mature; in the
former, as in Azolla, one spore grows at the expense of the
others, and finally fills the sporangium completely.

It has l)een generally supposed that no trace of an annulus
could be detected in the Marsiliacese. The writer has found,
however (Campbell (26)), in Pilularia Americana, traces of
a terminal annulus like that of the Schiz?eace?e. The ripe spo-
rangium, moreover, is strongly oblique like that of Scliizcra.

As the sporocarp ripens the outer cells Ijecome excessively
hard, especially the first layer of hypodermal cells (Fig. 256),
whose walls become so thick as to almost obliterate the cell
cavity. The second hypodermal layer is also thickened, but
not so strongly. At maturity the sporocarp of P. Americana
forms a globular body about 3 mm. in diameter, covered with
hairs, and attached to a long peduncle which bends downward

XI LEPTOSPORANGIATJE HETEROSPOREM 439

and buries the ripe sporocarp more or less completely in the
earth. The statement^ that this species has but three cham-
bers is incorrect, and except for the longer pedicel of the fruit,
and a slightly thinner epispore in the upper part of the macro-
spore, it corresponds exactly to P. glohulifera. The sporo-
carp splits into four parts, corresponding to the four lobes of
the young fruit, and the membranaceous margins of the leaf
form a tough indusium surrounding the sporangia. This in-
dusium is not, at least in P. glohulifera, readily pervious to
water, and germination does not begin for a long time after the
valves separate, unless the indusium is artificially opened.
Except for the number and position of the sori, and the relative
position of the two sorts of sporangia, Marsilia agrees exactly
with Pilularia. The sorus canals form two longitudinal rows
along the sides of the elongated fruit rudiment, which may be
compared to a pinnate leaf. In Marsilia, occupying the middle
line of each sorus, is a row of large tetrahedral cells, which
form three sets of segments, like any three-sided apical cell.
Each of these cells produces a group of sporangia. The ter-
minal one, derived directly from the apical cell, is a macro-
sporangium ; the smaller lateral ones, derived from its earlier
segments, the microsporangia.

Fossil LeptosporangiatcB

Sporangia of undoubted Leptosporangiatae are exceedingly
rare in the earlier geological formations. Solms-Laubach (2)
cites Plymenophyllites as probably being a genuine leptospo-
rangiate Fern, and Zeiller (i) describes some isolated spo-
rangia that seem to be much like those of the modern Gleich-
eniacese. Forms like the Osmundacese have also been de-
scribed by various writers, but no traces of Cyatheaceae or
Polypodiace^ have been yet detected in PaLxozoic formations.
In the Jurassic, undoubted evidences of GleicheniacCcX, Os-
mundacese, and Schizseaceae are found (Raciborski (i)), but
the Polypodiacese do not seem to have appeared until still later.
The existence of the Hydropterides below the Tertiary is
doubtful, but in the latter formation occur undoubted remains
of the living genera Salvinia, Pilularia, and Marsilia.

' Goebel (10), p. 240; Underwood (4), 2nd ed., p. 127; "Botany of Cali-
fornia," vol. ii. p. 352.

440 MOSSES AND FERNS chap.

Affinities of the Leptosporangiat^

The Osmundaceae undoubtedly are intermediate between
the Eusporangiat?e and Leptosporangiatae, but with which
order of the former their affinities are closest is difficult to say.
Among the Ophioglossaceae, the larger species of Botrychium
and HchiiuitJwstacJiys show apparent close structural similar-
ity to the Leptosporangiatae; but, on the other hand, in the
distinctly circinate leaves and the character of the sporangia,
as well as the histology, the Marattiaceae are certainly quite as
nearly related. Apparently all of these forms are generalised
types, springing from a common stock, but no two of them
directly related.

Among the Leptosporangiatae themselves the relationships
are evidently much closer. A common type of prothallium
and sporangium prevails throughout, even in the heterospo-
rous forms. The four families, Osmundaceae, Gleicheniaceae,
Cyatheaceae, and Polypodiaceae, form a pretty continuous
series, of which the Polypodiaceae are with very little question
the latest and most specialised forms. This is evinced both by
the geological record, which, so far as yet examined, shows
that they were the latest to appear, and by the fact that at
present they greatly outnumber the other Ferns, probably in-
cluding at least 90 per cent, of all living species. The single
genus Polypodium has over 400 species, probably as many as
all the lower Ferns combined. These facts, together with the
specialised character of all the parts, indicate that they are
Ferns which have adapted themselves to modern conditions.

The Schizaeaceae and Hymenophyllaceae do not seem to
belong to this main line, but are somewhat peculiar types, ap-
parently belonging near the bottom of the series. The Hymen-
ophyllaceae, on the whole, approach most nearly the Gleichen-
iaceae, with which they agree in many points, both in the sporo-
phyte and gametophyte, but they also recall the Osmundaceae,
and possibly may form a branch somewhere between the two,
but nearer the former. The peculiarities of the gametophyte
are probably in large measure the result of environment, and
the filamentous prothallium of some species of Trichomanes
and Schizcca is beyond question a secondary and not a primary
condition, and the prothallium is typically like that of the other
Leptosporangiatae. The nearest affinities of the Schizaeaceae

LEPTOSPORANGIAT^ HETEROSPOREJE

441

seem to be with the Osmundacese, but in the structure and ar-
rangement of their vascular bundles they are more like the
Gleicheniacese.

Of the two families of the Hydropterides, the Salviniaceae
shows several points of resemblance to the Hymenophyllacese.
The development of the leaves is strikingly like those of Hy-
menophyllace?e with reniform or palmate leaves, and the struc-
ture of the sori almost identical. The absence of secondary

Salvinia

Azolln

Eiispora ngiattP

roots in Salvinla is suggestive also of the similar absence in
some species of TricJioinanes. The two-sided apical cell of
the stem is, however, different from that of the few Hymeno-
phyllacese examined, which all possess the pyramidal initial,
but possibly further examination may show forms with an
initial cell similar to that of Azolla or Salvinia.

The Marsiliacese, except for their marked heterospory, are
typical leptosporangiate forms. The writer has been inclined
to assign them a position near the Polypodiaceae, but recent

442 MOSSES AND FERNS chap.

work on these forms has led to a somewhat different conclu-
sion (Campbell (26) ) . Both the anatomical structure, and the
character of the sporocarp and sporangium point to a not very
remote afihnity with the Schiz?eaceae. This view would har-
monise better with Belajeff's views as to the structure of the
antheridium in Marsilia. The two genera of the Marsiliacece
are evidently very closely related, and of these Pihilaria ap-
proaches nearer the homosporous Ferns. The accompanying
diagram shows the relationship assumed here.

CHAPTER XII

EQUISETINE^

All of the living representatives of the second class of the
Pteridophytes may without hesitation be referred to die single
genus Equisehim, with about twenty-five species, some of which,
e. g., E. arvcnse, are almost cosmopolitan. In the largest
species, E. giganteum, the stems reach a height of lo metres or
more, but are slender, not more than 2 to 3 cm. in diameter, and
supported by the surrounding trees and bushes. The smallest
species is E. scirpoides (Fig. 281, B), whose slender stems are
seldom more than 15 to 20 cm. in length, and often one milli-
metre or less in diameter. In spite of these differences in size,
the structure is remarkably uniform, both in gametophyte and
sporophyte. The following account is based mainly upon a
study of E. tclmateia,^ but applies" to the other species that have
been studied.

The Gametophyte

The ripe spore of Equisetum is globular and shows no
trace of the ventral ridges usually evident in tetrahedral spores.
Four distinct membranes surround it, the inner one (intine)
being exceedingly delicate, but with care showing the cellulose
reaction (Buchtien ( i ) ) . Outside of this are the exospore and
the elaters, between which lies ^another layer, ''Mittelhaut" of
Strasburger ((11), p. 199), belonging to the exospore. The
well-known elaters (Fig. 257, A) form two strips attached in
the middle and terminating in spoon-shaped appendages. The
elaters are usually more or less spirally twisted, and when dry
show faint oblique striations, except on the expanded ends.
They are extremely hygroscopic, and respond instantly to any

^ E. maximum Lam.

443

444

MOSSES AND FERNS

CHAP.

changes in the moisture of the atmosphere. A careful study of
the dehiscence of the sporangium shows that as it dries the
expansion of the elaters assists very materially in opening it,
and their function is something more than that of keeping the
spores together, as has been asserted (Buchtien (i), p. 15).
The striation of the elaters is merely the result of wrinkling by
drying, and when moistened this disappears completely. The
elaters show the cellulose reaction except upon the upper surface,
which is cuticularised.

The spores contain much chlorophyll, which in the dry
spores appears amorphous and gives them a dark olive-green
colour. So soon as the spore is moistened, however, it increases

Fig. 257. — In this and all the following figures of Equisetutn, the drawings were made
from E. telmateia (£. maximum, Lam.), unless otherwise indicated. A, ripe, dry
spore with expanded elaters, Xi8o; B, a similar spore placed in water, Xi8o; C,
D, germinating spores, X360; E, older stages of germination, X180; r, primary
rhizoid.

in diameter by about one-half through the absorption of water,
and the numerous small round chloroplasts then become very
evident. The nucleus is large, and occupies the centre of the
spore. After a short time the elaters and the outer layer of
the exposore are thrown off, and probably the rest of the ex-
ospore, as no trace of this can be seen in the young prothallium.
The spores quickly lose their power of germination, and
should be sown as soon as they are discharged. If this is done
germination begins almost at once, and within ten to twelve
hours the first division wall may be completed. Tlie chloro-
plasts rapidly multiply by division and often show a distinct
radiate arrangement, extending in lines from the nucelus to the
periphery. The first division may occur before the spore has

XII EQUISETINE^ 445

changed form, and in this case (Fig. 257, C) a small cell is cut
off by a strongly curved wall. Both cells contain chlorophyll,
but the nucleus of the smaller cell is smaller than the other.
In other spores there is first an elongation, as in Os)minda, and
the smaller end, which like that has some chlorophyll, but not
so much relatively as the larger, is cut off, and forms the first
rhizoid, and within twenty-four hours, under suitable condi-
tions, this may reach a length considerably exceeding the diame-
ter of the spore. Sadebeck ( (6), p. 177) showed and Buchtien

^IG. 258. — Young protliania of Equisetum, showing the variation in form, X i8o. In A
there is apparently a definite initial cell; r, rhizoid.

((i), p. 29) confirmed this, that the first rhizoid is positively
heliotropic.

The first divisions in the prothallial cell are extremely vari-
ous, in this recalling the behaviour of the eusporangiate Fili-
cinese and the Osmundacese. The first wall may be either ver*
tical or transverse (Fig. 257), and sometimes, but not often,
there are several transverse walls, and a short filament is
formed. More commonly the first transverse wall is followed
by a vertical wall in one or both cells. In case the first wall is
vertical it not infrequently happens that the two cells, by re-
peated transverse divisions, form two parallel rows of cells,
which may diverge, so that the young prothallium becomes two-
lobed. In a number of cases a two-sided apical cell was seen
(Fig. 258), but its growth is very limited. Finally, a cell-mass

446

MOSSES AND FERNS

CHAP.

occasionally is the first product of germination. As a not
infrequent occurrence may be mentioned also the suppression of
the first rhizoid (Fig. 258, C). The development for some
time is so varied that it is impossible to give any rule for it, but
generally the prothallium at this stage, like that of the lepto-
sporangiate Ferns, consists of but one layer of cells, and does
not show a midrib. These prothallia also do not have a definite
apical growth, and are usually more or less branched. Often,

Fig. .^59. — A, Female prothallium with the nrst archegonium (ar), X70; B, male pro-
thallium, X70.

however, the prothallium while still small has a somewhat cy-
lindrical body composed of several layers of cells, and in these
the rhizoids are mainly confined to the base. The chloroplasts
which these at first contain are gradually changed into leuco-
plasts, and may be completely absorbed (Buchtien (i), p. 17).
A comparison of the gametophyte with that of Lycopodium
ccrmium has been made (Jeffrey (2), p. 186), but as Goebel has
pointed out ((22), p. 409) there is this radical difference, — in
Equisctum the prothallium is dorsi-ventral, as it is in the Ferns,
while in Lycopodium it is radially constructed. The more or
less evidently upright form assumed by the prothallium in
EquisctiDu is due to the amount of light. Normally the pro-
thallium of E. tclmatcia is not upright, but more or less decid-
edly prostrate, as it is in the Ferns. (See Fig. 259, A.)

XII

EQUISETINE^

447

The Sexual Organs

The prothallia of Equisctum are usually dioecious and, as is
usual in such cases, the males are smaller and the antheridia
develop first. The latter generally appear in about a month.
In E. telmateia there is not so much difference in the appear-
ance and size of the male and female plants, and they are not
always distinguishable by the naked eye.

The first antheridia in E. pratense (Buchtien (i), p. 21),
may appear within four weeks on vigorous prothallia, and are
found at the tip, or upon the forward margin of the prothallium.
After the first marginal antheridia are formed, there is inau-
gurated an active division in the cells immediately adjacent, and
a sort of meristem is developed from w^iich new antheridia

Fig. 260. — Development of the antheridium, XiQo. A, Longitudinal section through
the antheridial meristem showing antheridia of different ages; B, longitudinal sec-
tion of young antheridium, X375; C, two sections of a terminal, single antheridium,
nearly ripe, X190; D, three transverse sections of young antheridium, X190;
Oj opercular cell.

arise, much as is the case in E.Jclmatcia, While In the latter
species, as in others, the antheridia may arise at the ends of
the prothallial branches, they also may be formed upon a meris-
tem quite like the archegonia, and are usually in groups, so that
longitudinal sections show antheridia of very different ages, all
evidently derived from the activity of the meristem (Fig. 260,
A). The development shows a close resemblance to that of
the eusporangiate Ferns, and in connection with the other points
in the growth of the gametophyte and sexual organs, suggests

448

MOSSES AND FERNS

CHAP.

a nearer connection of these two groups than is usually admitted.
As in the eusporangiate Ferns, the antheridiuni mother cell is
divided into an inner and an outer cell of which the inner one
forms at once the sperm cells. When the antheridium arises at
the end of a filament, the divisions in the terminal cell are very
much like those in Osinnnda. In the mother cell three intersect-
ing walls enclose a tetrahedral cell, which then has the cover cell
cut off by a periclinal wall. In Ix^th forms of antheridium the
subsequent history is the same. The central cell divides first
by a transverse wall, followed by vertical walls in each cell, and
subsequently by numerous divisions which show no definite
arrangement (big. 260, C), and produce a very large number
of sperm cells. In the cover cell only radial walls are formed,

Fig. 261. — Development of the spennatozoids, Xiooo. A, Three of the central cells of
an antheridium before the final division; B-D, final nuclear divisions in the sperm
cells; E-J, de.velopment of the spermatozoid from the nucleus of the sperm cell;
K, two free spermatozoids; v, the vesicle; b, blepharoplast. (I. J., after Belajeff).

and it thus remains single-layered, as in Maraffia and Osinnnda,
There is often a triangular cell (Fig. 260, D, o), recalling the
opercular cell in these forms.

From the prothallial tissue adjacent to the sperm-cells, there
is usually cut off a mantle of tabular cells enclosing the sperm-
cells, much as is the case in Marat tia and Bofrychium. The
dehiscence of the antheridium is caused by the separation of the
cells of the outer-wall, but no cells are thrown off.

XII EQUISETINEJE 449

Development of the Spermatozoids

The large size of the spermatozoids of Equisetiun makes
them especially suitable for the study of their development, and
this was traced with some care in E. felniateia. Belajeff (6),
more recently, has studied the development of the spermatozoid
in E. arz'ense.

The nuclei of the sperm cells previous to their final division
are globular and show one, sometimes two, small but distinct
nucleoli, and numerous chromosomes. In exceptional cases the
two blepharoplasts could also be seen. Previous to the final
division the latter take their place on opposite sides of the now
somewhat flattened nucleus, whose nucleolus cannot be distin-
guished and whose chromosomes are very distinct, short, curved
bodies. Their number could not with certainty be determined.
The nucleus passes through the various karyokinetic phases,
and the blepharoplasts occupy the poles of the nuclear spindle.
The resting nuclei, as in other cases, show no nucleolus. Fig.
261, F, shows the earliest stage in the differentiation of the
spermatozoid, and this corresponds exactly with what I have
observed in various Ferns, and differs somewhat from Buch-
tien's figures of corresponding stages. The nucleus, which is
not noticeably lateral in position, shows a narrow cleft upon one
side. Seen in profile (Fig. 261, F, i), one side projects some-
what more than the other, and becomes the anterior end, which
later becomes thinner than the posterior part. I was unable to
see that this forward part behaved differently from the hinder
part with regard to the nuclear stain employed, nor could I sat-
isfy myself of the presence of the cytoplasmic anterior prom-
inence which Strasburger ((11), IV., PL iii) figures in the
Ferns.

In some cases the blepharoplast could be seen (Fig. 261, E-
H) and in the older stages this was much elongated, extending
beyond the pointed end of the ^nucleus ; but perhaps owing to
the fixing agent used — chromic acid — the formation of the cilia
from the blepharoplast did not show at all clearly, while Belajeff
indicates (Fig. 261, I) that they are very conspicuous. Per-
haps also due to unsatisfactory staining, my preparations did
not show at all clearly the cytoplasmic envelope about the nu-
cleus which is so conspicuous in Belajeff's figures. (See Fig.
261, J.)

The body rapidly elongates and becomes quite homogeneous,
29

450 MOSSES AND FERNS chap.

but this does not occur until a comparatively late stage. The
nucleus is here somewhat flattened to begin with, and the coils
of the spermatozoid lie nearly in the same plane and resemble
a good deal those of Marattia, except that they are larger. The
protoplasm enclosed within the coils is conspicuously granular,
and forms the large vesicle attached to the posterior coils of the
free spermatozoid. The mucilaginous change in the walls of
the sperm cells begins about the same time as the differentiation
of the spermatozoids.

The free spermatozoids consist of from two to three com-
plete coils, of which the forward one or two are very much
smaller than the very large and broad hinder one, which encloses
the vesicle. The cilia are much like those of the Fern sperma-
tozoid, but somewhat shorter. Tlie cover cells of the ripe an-
theridium are forced apart by the swelling of the mucilage from
the disorganised walls of the sperm cells, which are forced out
of the opening into the water, where the remaining wall of the
sperm cell is dissolved and the s-permatozoid set free. AMien
in motion a peculiar undulation of the large posterior coil is
conspicuous, a phenomenon which has also been observed in the
quite similar spermatozoids of Osiminda.

The young female prothallium is always a cylindrical mass
of cells with a series of thin lateral lobes. After the archesronia
begin to form and a definite apical meristem is established, the
formation of these lobes is almost exactly like the similar ones
in young plants of Anthoceros fusiforniis. The exact relation
of the growing point in the older prothallium to the primary
one could not be made out. In the former this arises, according
to Buchtien (i), upon the under side of the prothallium, with-
out any apparent relation to the primary growing point. This
much is certain, that just before the first archegonium appears,
there is formed a cushion not unlike that of the Ferns. In the
youngest condition this in profile (Fig. 262, A) shows an evi-
dent apical cell (probably one of several), not unlike that of the
Ferns; but the great difficulty of obtaining accurate sections
through it made it impossible to follow exactly its further de-
velopment. This much can be stated confidently, however,
that at the time when the first archegonia are produced, the
structure of the prothallium is essentially that of Osmunda
or Marattia, and consists of a central massive midrib and a
one-celled lamina, which is not continuous, but composed of

XII

EQUISETINE^

451

separate lobes. A similar condition exists in Osmnnda, where
in the older prothallia similar but much shorter and broader
lobes arise alternately from either side of the growing apex.

The development of the archegonium is intimately associated
with the formation of the lobes. The archegonium mother cell
is formed close to the base of the young lobe upon the ventral
side. By subsequent growth of the tissue between it and the
apical meristem, it is subsequently forced to tlie upper side, but
its origin is ventral, as in the Ferns. The lobe at whose base

Fig. 262. — Development of the archegonium. A, Optical section of the very young
archegonial meristem, X225; B-E, longitudinal sections of young archegonia, X4S0;
c, neck canal cell; v, ventral canal cell; 0, egg.

it is borne grows for some time by a definite apical cell, which is
very evident in horizontal section^ (Fig. 263, C).

The development of the archegonium most nearly resembles
that of the eusporangiate Ferns. Usually, but not always, no
basal cell is formed, and the first division in the inner cell sepa-
rates the neck canal cell from the central cell. Both neck and
ventral canal cells (Fig. 262, E) equal in breadth the central
cell, and in this respect are most like the Marattiacese. The
neck canal cell later grows up between the neck cells, but there
is usually a space between its summit and the terminal neck

452

MOSSES AND FERNS

CHAP.

cells, which here are much longer than the others. It subse-
quently divides by a transverse wall, as may happen in the
Marattiaceae and occasionally in Osmunda, but whether this
always takes place is not certain (Fig. 263, A). The four rows
of neck cells are all alike, and consist ordinarily of three cells

Fig. 263. — A, Longitudinal section of nearly ripe archegonium, with two neck canal
cells (r, c XSSo; B, section of an open archegonium, X27S; C, D, two cross-
sections of a young archegonium; L, the lobe at the base of which the arche-
gonium is formed, XS50.

each, the terminal ones being very long, and when the archego-
nium opens bending back strongly, but not becoming detached.
The central cell is surrounded by a single layer of tabular cells
cut off from the adjacent prothallium tissue, but these divisions
may extend to the lower neck cells (Fig. 263, A). The ^^g
is globular and shows no peculiarities of structure. Buchtien's
((i), p. 24) account of the further development of the mer-
istem, as well as his figures, point to something very much like
a repeated dichotomy of the growing point ; a further investiga-

XII EQUISETINEJE 453

tion of the exact origin of the primary meristem and its relation
to the secondary ones found in the branches is much to be
desired.

Jeffrey finds in E. arvense, E. hiemale, and E. limosum, that
the neck canal cell usually divides longtitudinally, and compares
it with the divisions in the archegonium of Lycopodhim
phlegmaria. This division may take place in E. tehnatcia, but
is exceptional. It may be mentioned that a similar division has
been observed in Mar ait ia Douglasii.

Each archegonium stands between two lobes, the one from
whose base it has itself developed, and the next younger one.
As these lobes in vigorous prothallia grow to a large size, and
branch, this gives the prothallium an extremely irregular out-
line, recalling very much that of Anthoceros pnnctafus or A.
fiisiformis. These branching lobes are not to be confounded
with the branches of the prothallium body due to the dichotomy
of the archegonial meristem. These latter are always short,
and project but little compared to the secondary branching lobes
produced from them. The entrance of the spermatozoids and
the changes subsequent to fertilisation seem to be exactly the
same as in Ferns.

The prothallia are normally dioecious, but this is not ex-
clusively the case. To a certain extent the external conditions
influence the production of males or females, as in the Ferns,-
and unfavourable conditions of nutrition tend to increase the
proportion of the former.

According to Hofmeister (i) the number of archegonia
upon vigorous prothallia varies from twenty to thirty. His
statement that this exceeds the number of antheridia in the
larger male prothallia is not confirmed by Buchtien, who found
as many as 120 of the latter in some cases.

Usually more than one archegonium is fertilised, Hof-
meister having found as many a3 seven embryos upon a single
prothallium. He does not state how many of these develop.
The embryo corresponds closely to that of the Ferns, and has
been carefully described by Sadebeck (6).

The Embryo

The fertilised tgg grows until it completely fills the ventral
cavity, and its granular contents become more separated, and

454

MOSSES AND FERNS

CHAP.

the nucleus is decidedly larger than l3efore fertilisation. The
lower neck cells approach and apparently become grown to-
gether, and as the divisions in the lower neck cells here contrib-
ute to the calyptra, the young embryo becomes more deeply
sunken in the prothallial tissue than is common in the Ferns.
The basal wall is transverse, as in the Marattiaceae, and the
formation of the quadrants takes place as usual. The position
of the quadrant walls is, however, sometimes slightly different,

Fig. 264. — A, Longitudinal section of the venter of a recently fertilised archegonium,
X300; B, a similar section of an archegonium with the young embryo; C, D, two
transverse sections of a somewhat older embryo, X300; st, apical cell of the stem;
r, apical cell of the root; E, longitudinal section of an older embryo, X300; I» I»
the basal wall.

being often decidedly inclined in both epibasal and hypobasal
halves (Fig. 264, E). In the former the larger of the two
primary cells is the initial for the stem, and its large size, com-
pared to the leaf quadrant, already points to the greater develop-
ment of the stem in the sporophyte compared to the leaves. Of
the hypobasal quadrants the larger becomes at once the root,
whose axis is nearly coincident with that of the stem.

Jeffrey ( (2), p. 169) thinks that in E. hicmale the root also
may be of epibasal origin, but his figures 7 and 8 are capable of

XII

EQUISETINE^

455

a different interpretation, and to judge from them it is quite as
likely that the root is hypobasal as in the other species examined.
The first two divisions in the stem quadrant establish the defini-
tive apical cell, which occupies nearly the centre of the epibasal
part of the embryo, and is surrounded by a circle of four cells,
two of which belong to the leaf quadrant (Fig. 225, C) , and two
are segments of the stem quadrant, the first one corresponding
morphologically to the second leaf of the Fern embryo. This

Fig. 265. — A, An advanced embryo of E. arvcnse, surface view, X360; B, optical
section of a similar stage of E. palustre, X360; older embryo of E. arvense, X160;
St, stem; R, root (all the figures after Sadebeck).

circle of cells forms the first sheath about the stem of the young
sporophyte. After one set of lateral segments has been cut off
from the root quadrant, the primary cap cell is formed as in the
Ferns. Unlike the latter, the divisions in the stem apex proceed
rapidly, and it soon projects in the centre of the embryo as a
broad conical prominence, terminating in the large tetrahedral
apical cell.

The three parts of which the primary leaf-sheath is com-
posed remain distinct and form the three teeth (Fig. 265, C),
which grow rapidly until they are about on a level with the
apex of the stem. This growth is mainly due to the activity
of the marginal cells. The root grows less actively at first than
either stem or leaves, and at the time the latter is nearly fully
developed forms but a small protuberance at the base of the
embryo (Fig. 265, C). The foot at this time is not conspicu-

456 MOSSES AND FERNS chap.

ous, but later enlarges more. Its cells are in close contact with
the prothallial cells. The root now grows rapidly downward,
penetrating through the prothallium until it reaches the ground.
The stem apex rapidly elongates and grows upward through the
calyptra. The embryo thus perforates the prothallium both
above and below, as in Marattia, although owing to the position
of the archegonium in the former, the relation of the embryo to
the archegonium is not the same.

The root in E. hieinalc and E. arvcnse (Jeffrey (2), p. 169)
penetrates the earth before the shoot breaks through the calv])-
tra, but in E. liinosum, the emergence of the root occurs at a
much later period. At the time the shoot emerges from the
calyptra, there is already developed the rudiment of the bud
that is to form the second shoot. This bud is formed above the
origin of the primary root, between two of the primary leaf-
traces. At this time there are already developed three or more
leaf-whorls about the shoot-axis. The second shoot does not
develop its first root until its first foliar sheath is well developed.

In most species that have been studied, the primary shoot
has the leaves of the whorls in threes, but in E. variegatiim
(Buchtien (i), p. no) there are regidarly but two leaves in
each whorl, and Jeffrey found that this was sometimes the case
in E. limosum.

The development of the primary axis, unlike that of the
Filicinese, is limited, and it ceases growing after producing ten
to fifteen sheaths, which, like the first one, are three-toothed.
The stem remains very slender, but shows the marked division
into nodes and internodes found in the later ones. This pri-
mary stem has irregular lacunae in the cortex, but does not show
the cavity so conspicuous in the central part of the older plant,
and in E. tcUnatcia, according to Buchtien, this is quite solid.
In this species he figures four vascular bundles, whose xylem is
relatively much better developed than in the later stems. The
bundles, like all of those in the stem and leaves, are collateral,
and the whole group is surrounded by a well-marked endo-
dermis. From the base of this primary shoot a second stronger
one develops. This second shoot is much more vigorous, and
its leaf-sheaths have four teeth. From the base of this others
arise in the same way and in rapid succession. Sometimes the
third, or one or more of the later formed basal shoots, bends
downward and penetrates the earth, producing the first of the

XII

EQUISETINE^ 457

characteristic rhizomes. The first of these have also four-
toothed sheaths, but the branches produced from them graduaUy
assume the characters of the fully-developed shoots, some of
which ultimately bear sporangia. The first shoots of the sporo-
phyte, even in such species as later branch very freely, produce
only an occasional branch, which breaks through the base of the
sheath.

In E. hiemalc, there is found, according to Jeffrey, a gradual
transition from the typical arrangement of the tissues of the
root, to those in the base of the young shoot. There is first
developed in the latter an unbroken tube of reticulate tracheids,
which Jeffrey considers to be a reversion to an originally cylin-
drical stele. However, as this same arrangement is repeated
in the succeeding nodes, it seems much more likely that this
ring of tracheary tissue merely represents the basal node.
Within the ring of tracheary tissue is a mass of parenchyma,
and outside a zone of phloem bounded by a typical endodermis.
The rudiment of the second shoot causes a break in the vascular
ring above its point of origin. In the internode there are three
vascular strands, corresponding to the three teeth of the foliar-
whorl. In short, the structure of the primary shoot is essen-
tially the same as that of the stouter shoots developed subse-
quently. Although Jeffrey speaks of a ''central-cylinder," there
is nothing in his account to show that the vascular bundles do
not originate from the primary cortical tissue, as they do in the
adult shoots.

The Mature Sporophyte

On comparing the sporophyte of Eqmsefiim with that of
most Ferns, the greatest contrast is in the relative importance
of stem and leaves. The stem in all the Equisetinese is extra-
ordinarily developed, while the leaves are rudimentary, in strong
contrast to their great size and complexity in most Ferns. All
species of Eqiiisetnm produce a more or less developed under-
ground rhizome, which often grows to a great length and rami-
fies extensively. This, like the aerial branches developed from
it shows a re^-ular series of nodes and internodes. The latter
are marked by longitudinal furrows, and about each node is a
sheath whose summit is continued into a number of teeth, vary-
ing with the size of the stem. Corresponding to each tooth

Fig. 266. — A, Upper part of a fertile shoot of E. tclemateia, X i ; T?, lower part of a
vegetative shoot, with young branches for the next season's growth, X i ; T, tubers;
C, cross-section of an internode of the fertile shoot, X4; L. cortical lacunae; D,
sporangiophores, X4; E, median section of a single sporangiophore, X6; sp,
sporangia.

XII

EQUISETINEM 459

of the sheath there is developed an axillary bud, which may
either at once develop into a shoot, subterranean or aerial, or
these buds may remain dormant for an indefinite period, being
capable of growing, however, under favourable conditions.
The surface of the rhizome in E. tclmatcia, especially at the
nodes, is covered with a dense dark-brown felt of matted hairs,
and a whorl of roots occurs at each node, corresponding in num-
ber to the number of axillary buds, from whose bases the roots
really grow. Sometimes the buds become changed into tubers
(Fig. 266), which are especially common in E. tclmateia and E.
arvcnse. These tubes are protected by a hard brown scleren-
chymatous rind, within which is a mass of starchy parenchyma,
traversed by the slender vascular bundles. In some cases these
buds form in chains and are then seen to be the swollen inter-
nodes of short branches.

The aerial stems are of two kinds, sporiferous and sterile.
In one group the only difference between the two is that the
former bear at the apex the sporangial strobilus ; in the second,
of which E. tclmateia is an example, the sporiferous branches
are almost entirely destitute of chlorophyll and quite un-
branched, while the green sterile shoots are extensively
branched. In such forms the fertile shoots die as soon as the
spores are shed, and usually appear before the green shoots are
developed.

The Stem (Rees (2) ; Sachs (i) ; Janczezvski {3) ; Jeffrey (2) )

A longitudinal section of one of the numerous subterranean
buds (Fig. 267) shows that the conical apex of the stem is
occupied by a large pyramidal cell whose segmentation is ex-
ceedingly regular. The youngest of the foliar sheaths is sepa-
rated from the apex by several segments, but below, the next
older sheath is very close to it,^and the internode, which in the
older stem is so conspicuous, is scarcely perceptible. The
closely-set sheaths grow very rapidly, so that all but the young-
est ones extend beyond the stem apex, which is thus very com-
pletely protected. They form a compact, many-layered cover-
ing about it, presenting very much the appearance of the leaf-
buds of many Spermaphytes. The apical cell shows the usual
three series of lateral segments. These are arranged in three
rows, but owing to a slight displacement in the younger ones,

460

MOSSES AND FERXS

CHAP.

the teeth of the sheaths alternate. Each cycle of three seg-
ments comes to lie practically in the same plane, and consti-
tutes a disc which later forms a node and internode of the stem.
Each segment is first divided by a wall nearly parallel to the wall
by which it was cut off from the apical cell, into two overlying
cells. The upper cells or semi-segments give rise to the nodes,
the lower to the internodes.

The next walls are like the sextant walls in the roots of
the Ferns, and a cross-section just below the apex presents
exactly the same appearance. Each cell now divides by walls,

Fig. 267. — A, Median section of a strong subterranean (vegetative) bud, X30; k,
lateral bud; B, the apex of the same section, X200.

apparently not always in the same order, parallel with the
primary and lateral walls, and very soon there are periclinal
divisions by wliich an inner cell is cut off from each segment
cell that extends to the centre. This primary group of central
cells is the pith, which later in the internodes is usually torn
apart and destroyed, leaving the large central hollow met with
in all the larger species of Equisctiim. From the outer cells
are developed the leaves, the vascular bundles, and cortex.

The annular leaf-sheaths begin as outgrowths of the super-
ficial nodal cells of each cycle of segments, and these form a
circular ridge or cushion running round the base of the apical
cone. The summit of this ridge is occupied l>y a row of mar-
ginal cells, which are the initial cells, and from these segments
are cut off alternately upon the inner and outer sides (Fig. 272,

XII

EQUISETINE^

461

A) . The growth is stronger at certain points, which, according
to Rees, have a definite relation to the early divisions. Thus in
E. scirpoidcs the teeth are always three, and correspond to the

Fig. 268. — Transverse section of a young vegetative shoot just below the apex, X260; B,
outer part of a section lower down, X260; pr, procambial zone; C, young vascular
bundle, X520; t, primary tracheids.

primary nodal cells; in E. arvense there are six or seven, in
the first case corresponding to the sextant cells, in the latter to
the sextant cells plus the first division in one of them. In the

462 MOSSES AND FERNS

CHAP.

large species, like E. tclmatcia, it is difficult to trace any such
relation. In most forms, by subsequent dichotomy of some or
all of the primary teeth, others are formed, so that the number
in the fully-developed sheath exceeds that first formed. As
soon as the young sheath begins to project, a section through
one of the teeth shows that it is divided into an upper and lower
tier of cells, the apical cell terminating the upper one. This
division no doubt corresponds to the first horizontal division in
the outer nodal cell from which the leaf-tooth originally comes.
In one a little older (Fig. 272, B), in this upper tier of cells a
line of cells occupying the axis is evident {fb), extending from
the base of the leaf nearly to the summit, and growing at its
outer end by the addition of cells derived from the inner part of
the youngest upper segments of the terminal cell of the leaf.^
This is the beginning of the single vascular bundle found in each
leaf. 1

Shortly after this first indication of the vascular bundle of
the leaf can be seen, the cells of the cortex immediatelv outside
the central pith begin to divide rapidly by longitudinal walls and
form a zone of cambiform cells completely surrounding the
medulla. In the primary central row of cells in the leaves
similar divisions occur, and a very evident procambium cylinder
is formed, bending in and joining the procambium zone of the
cortex. At the point of junction the cells are shorter and
broader, and the cortical cells lying outside are also much
broader, so that the cortical procambium is very conspicuous.
If cross-sections are examined about this time, in the procam-
bium zone are found a number of groups of cells where the
divisions are more rapid, and the resulting cells narrower than
the surrounding ones. These are the separate vascular bundles,
and are continuous with those in the leaves (Fig. 269). The
first permanent tissue consists of one or two small annular
tracheids upon the inner side of the bundle (Fig. 268, C).
These are followed by several others. They first form in the
internodal part of the bundle and only later in the foliar portion.
The nodal tracheids joining the xylem of the foliar and inter-
nodal bundles are very irregular short cells with annular thick-
enings upon their walls. Later two small groups of larger
spiral trache?e are formed at the sides of the xylem, but the

' Each tooth is here regarded as a leaf, the sheath as a circle of con-
fluent leaves.

XII

EQUISETINE^

463

greater part remains but little changed. By this time, in
E. teUnateia, numbers of cells with peculiar contents are noticed
scattered through the pith and cortex (Fig. 269). The con-
tents of these are dense, and stain deeply, indicating the presence
of mucilaginous matter, and probably tannin, their appearance
and behaviour being very much like the tannin cells of Angiop-

teris or Marattia.

In the older parts of the section the nodal cells remain short,
while the internodal cells elongate very much and separate the
nodes with their attached foliar sheaths. With this growth is
associated the formation of the characteristic lacunae. In all

Fig. 269.— Longitudinal section of the young stem, shov/ing the junction of the foliar
and internodal bundles; tr, the primary tracheids; x, x, tannin-bearing cells.

the large species the growth qf the medullary cells very soon
ceases to keep up with the expansion of the stem, and they are
torn apart and almost completely disappear, leaving a great cen-
tral cavity in each internode separated from the neighbouring
ones by a thin diaphragm,— all that is left of the medulla in the
fully-developed stem. The leaves of successive sheaths alter-
nate, and a study of the course of the vascular bundles shows
that at each node the alternating bundles of successive inter-
nodes are connected by short branches. Corresponding to the

464 MOSSES AND FERNS

CHAP.

vascular bundles are ridges upon the surface of the internodes
and foliar sheaths, due to greater growth at these points,
as a result of which a regular series of cortical lacunae (vallecu-
lar canals) is formed, alternating with them (Fig. 266, C),
and lying just outside of the cortical zone containing the vascu-
lar bundles. In some of the small species of Equiscfum, as in
the primary shoot, the central lacuna is absent.

A cross-section of the fully-developed stem of E. telmatcia
(Fig. 266, C) shows this very regular arrangement of the vas-
cular bundles and lacunae. In addition to the large cortical
ones, each vascular bundle has, on the inner side, a large air-
space, which like the other is formed by the tearing apart of the
tissues of the bundle. In this way the primary tracheids are
torn apart and often destroyed, so that all that remains of them
are the isolated thickened rings adhering to the sides of the
canal. The bundle is strictly collateral in structure, and very
much resembles that of many grasses and other simple Mon-
ocotyledons. The phloem is composed of sieve-tubes, which,
according to Russow (i), have only horizontal sieve-plates,
and no lateral ones as in the Ferns. These are mingled wnth
cambiform cells. In the species In question there is in addition
a zone of bast fibres at the outer limit of the phloem.

Surrounding the w^hole circle of bundles in E. telmatcia,
E. arz'cuse, and several other species, there is a common endo-
dermis (Fig. 270, cu). In others the arrangement is different
(Pfitzer (i) ; Van Tieghem (6)). Thus in E. limostun, each
separate bundle has its own endodermis; in E. hieiualc there is
a common inner as well as an outer endodermis in the aerial
stems, while the bundles of the rhizome are like those of E. limo-
suin. Inside the endodermis lies the single pericycle.

There has been some controversy as to the nature of the vas-
cular system in Equisctuin. Van Tieghem (6, 8) describes the
stem of Equisctuin as ''astelic"; Strasburger ((11), vol. 3)
considers it as monostelic. Jeffrey has attempted to reduce the
structures to his ''siphonostelic" type, /. c, he would compare
the complex of vascular bundles to the cylindrical stele of the
Ferns and Lycopods. The spaces between the vascular strands
of the internodes he considers as *'gaps" comparable to the foliar
gaps in the stele of the Ferns, or the ramular gaps in the stele
of the Lycopods. He is, moreover, of the opinion that the solid
stele C'protostele") found in the fossil Sphenophyllales is the

XII

EQUISETINE^

46s

prototype of the "siphonostele," which he thinks is the condition
found in Equisetum. He seems, however, to have overlooked
the fact that in the adult shoot, at least, of Eqiiisehim, the whole
vascular system of the stem originates from the primary cortex
or periblem, the original central tissue-cylinder giving rise only
to the pith. Moreover, his assumed 'Vamular gaps" are found
equally developed whether branches are developed or not, and
are obviously related to the leaf-traces of the internode.

All the cortical cells are separated by small intercellular
spaces, which are very conspicuous in the soft tissue of the

en.

Fig. 270. — Transverse section of the vascular bundle of a fully-developed vegetative
shoot, X75; i, i, lacunae; x, x, tannin cells; t, t, remains of the primary tracheids;
en, endodermis.

fertile stems of E. telmateia and E. arvense. In all of the inter-
nodes of the main axes of E. telmateia chlorophyll is absent,
but in most species the principal assimilative tissue is situated
here. It consists usually of isolated masses of transversely ex-
tended green cells separated by strands of colourless sclerenchy-
matous fibres, which form the ridges so prominent upon the in-

ternodes and foliar sheaths. Seen in cross-section the masses of
30

5>> '■ ^^

'^.

Fig. 271.— Development of the stomata. A-C, Surface views of very young stomata of
E. telmateia, X600; D, section of an older stoma of E. limosum, X 700 (after
Strasburger) ; E, outer surface of a complete stoma of E. telmateia, showing the
silicious nodules upon the epidermal cells; F, inner side of the same, showing the
silicious bars upon the inner walls of the guard cells; v. v, accessory cells; s,
guard cells.

XII

EQUISETINE^ 467

green cells are concave outwardly and lie beneath the ridges.
In secondary branches the amount of this tissue is much greater
and the lacunae less conspicuous, or indeed even wanting.

The epidermis, as is well known, contains great quantities of
silica, which gives it its very rough and harsh surface. This
is deposited either uniformly, as is usually the case in the lateral
cell walls, or in tubercular masses. Upon the inner surface of
the guard cells of the stomata it forms regular transverse bars
(Fig. 271). Upon the outer walls of the epidermal cells the
masses form either isolated bead-like projections or these are
more or less completely confluent.

The stomata are peculiar in structure, and their development
w^as first correctly described by Strasburger (i). In E. tel-
mateia these only occur usually upon the foliar sheaths, but in
species with green internodes they are found principally upon the
sides of the furrows over the green hypodermal tissue.^ Before
the stoma proper is formed, the cell divides twice by longitudinal
walls (Fig. 271), and the original cell is thus divided into a
central one (the real stoma mother cell) and two narrow lateral
accessory cells. The central cell now divides again, and the
division wall splits in the centre as usual. A cross-section of
the young stoma (Fig. 271, D) shows that the walls b}^ which
the accessory cells are cut off are inclined, so that the stoma
cell is broader at the bottom than at the top, and as develop-
ment proceeds the accessory cells completely overarch the stoma,
and in the older ones look as if they had arisen by horizontal
divisions in the primary guard cells. The accessory cells show
the same tuberculate silicious nodules upon their outer w^alls as
the other epidermal cells, and upon the inner face of the real
guard cells only are formed the regular bars. Stomata are quite
absent from the rhizome, and also from the colourless fertile
branches of E. tchiiafeia. Compared with the aerial stems, the
rhizome shows a smaller number of vascular bundles, and a cor-
responding reduction in the number of the lacunae.

The Branches

Until the researches of Janczewski (3) and Famintzin (i)
it was supposed that the lateral branches arose endogenously.

' Miss E. A. Southworth (i) found that in B. arvense they occur upon
the ridges, and upon the fertile as well as the sterile shoots.

468

MOSSES AND FERNS

CHAP.

Their researches, however, showed conclusively that this was
not the case, but that the origin is exogenous. In most species
they are produced abundantly, and a bud is formed in the axil
of each leaf, although it frequently happens that some of them
do not develop fully. In E. telmatcia they do not occur at all,
as a rule, upon the colourless sporiferous shoots, but are regu-
larly formed from all but the lowest nodes of the sterile stems.

Fig. 272. — Longitudinal section of a young vegetative shoot showing two young
leaves (L.), X200; B, section passing through the base of a somewhat older leaf;
fb, vascular bundle; C, section passing through a young bud (,k).

In E. scirpoidcs they are absent from all the aerial stems, but
whether rudiments of them are formed does not seem to have
been investigated.

Their development may be readily traced in a series of
median longitudinal sections through a vigorous sterile stem of
E. telmatcia or E. arvcnsc before it appears above ground. The
young bud (Fig. 272, C) originates from a single epidermal
cell just above the insertion of the leaf. This cell enlarges and
is easily recognisable. In it are formed three intersecting walls
cutting out the apical cell, w^hich at first is somewhat irregular,
but soon assumes its definite form, and the subsequent growth
of the branch resembles in all essential points that of the main

XII

EQUISETINEM

469

shoot. Very early the cells of the leaf-base immediately above
the young bud grow around it like a sheath, and finally become
grown together with the epidermal cells of the axis above the
bud, which thus lies in a completely closed cavity. As the bud
grows it gradually destroys the tissue surrounding the cavity,
and finally breaks through the base of the leaf, appearing from
the outside as if it had developed from below and not from the
axil of the leaf. In most species these branches remain simple,

Fig. 2y:i. — Section of a lateral bud, enclosed within the sheath formed by the leaf-base,

X175.

but in E. sylvaticiim and E. giganteum the secondary branches
also ramify.

The Roots

The formation of the roots is intimately connected with that
of the lateral buds. Each bud normally produces a single root
below the first foliar sheath, which in the buds derived from the
rhizome all develop, whether the buds themselves grow further

470

MOSSES AND FERNS

CHAP.

or not. According to Janczewski, certain of these rhizogenic
buds of the rhizome produce several roots, but the buds remain
otherwise undeveloped. In the aerial stems the roots remain
normally undeveloped, but may often be stimulated into growth
by keeping the stem moist and dark.

Van Tieghem ((5), p. 551) describes the roots of E. paliis-
fre as being exogenous, and says they can be traced to a definite
cell of one of the young segments. Janczewski ((3). p. 89),
however, was unable to recognise the young root until the first

Fig. 274. — A, Longitudinal section of the root apex, X200; x, x, the large central ves-
sel of the vascular bundle; B, C, two transverse sections passing through the apex,
X200. In C is shown the first divisions of the cap cell.

foliar sheath was well developed, and in E. tehnateia I could see
no trace of the root in still older buds, and they w^ere apparently
always of endogenous origin, although this point was not spe-
cially investigated.

The structure of the apical meristem is much like that of
the leptosporangiate Ferns, the main difference being the greater
development of the root-cap, in which periclinal walls are fre-
quent, so that the older layers, especially in the middle, are
several cells thick, and not clearly limited.

After the sextant walls are formed, each semi-segment is

XII

EQUISETINE^

471

divided at once into an inner and an outer cell, the former
giving rise directly to the plerome or central cylinder. The
next division (seen in longitudinal section) separates the epi-
dermis initials from the cortex. A cross-section of the young
plerome immediately after the first divisions have taken ])lace
(Fig. 275, A) shows that the three primary cells are of une(|ual
size, and that the two smaller ones divide first. From the larger
one, the first periclinal wall separates a central cell, w^hich occu-
pies almost exactly the middle of the section, and this stands
immediately above the corresponding one in the older segments,
so that in longitudinal sections (Fig. 274) these form a very
conspicuous axial row of cells {x, x), which together constitute

Fig. 375. — Three transverse sections of the young root, X200; en, endodermis; v, cen-
tral vessel.

the single large vessel wdiich occupies the centre of the older
bundle. The endodermis becomes separated by this time, and
a little lower down divides by periclinal walls into the two layers
found in the completely developed root. The tissues of the cen-
tral part of the young root are very regularly disposed (Fig.
275, B, C). In the centre is the large vessel already described,
around which are arranged at first a single row of usually six
or eight cells (Fig. 275, B). By these first divisions the sepa-
ration of the xylem and phloem of the bundle is complete. If
there are six of these primary cells the bundle will be triarch, if
eight, tetrarch. In somew^hat older sections of a tetrarch bun-
dle (Fig. 275, C) four of the primary cells are still recognis-
able and have divided but little. These form the four groups

472 MOSSES AND FERNS chap.

of tracheids of the older bundle. The intermediate cells divide
much more rapidly and constitute the phloem. The number
of endodermal cells in a cross-section corresponds generally to
the number of xylem and phloem masses. The peripheral
groups of tracheae early develop spiral thickenings upon their
walls, and sometimes there is but a single row of tracheae in each
xylem mass. Each of the three phloem masses of E. variega-
tum has three narrow sieve-tubes in contact with the inner endo-
dermis surrounded by thin-walled cambiform cells. The thick-
enings upon the walls of the large central vessel form only at a
late period.

Intercellular spaces arise at the angles of the outer endo-
dermal cell, and similar ones also between the outer cells of the
cortex, which becomes very spongy in the older roots. Numer-
ous brown root-hairs, like those upon the rhizome, cover the
surface of the root. A pericycle is quite absent, and the sec-
ondary roots arise from the inner endodermis in direct contact
with the tracheids. The latter, as will be seen from the figure,
lie between two endodermal cells, and the young root lies there-
fore not directly opposite, but to one side of the corresponding
xylem mass. The young roots may arise from either of these
endodermal cells, and consequently there is formed a double
row of rootlets corresponding to each xylem mass of the
bundle. Shortly after the rootlet is formed, the endodermal
cell outside it divides by a tangential wall, and this develops into
a double layer of cells completely enclosing the young rootlet
(Van Tieghem (5), p. 395). A similar ''digestive pouch" is
formed, according to Van Tieghem, in the roots of many Ferns,
but is in these derived from the cortex outside the endodermis.
The double endodermis of the bundle of the older root shows
the characteristic foldings of the radial walls only upon the outer
cells.

Cormack ( i ) has recently published a paper showing that in
E. maximmn (tehnafeia) there is a slight secondary increase in
thickness in the nodes of the stem, due to the presence of a
genuine cambium, not unlike that in the stem of Botrychium,

The Sporanghim {Bozvcr (15))

In all species of Equisctum the sporangia are formed upon
the under side of peltate sporophylls arranged in closely-set

XII

EQUISETINE^

473

circles about the upper part of the axis of the fertile shoots
(Figs. 266, 281). A section through the apex of the young
shoot shows much the same structure as a sterile one, but the
apical cell is smaller and the leaves do not arise so near the sum-
mit. Circular foliar sheaths are formed in the same way, but
the leaves form rounded elevations, either entirely separated or
but slightly joined (Fig. 276). These are at first nearly hemi-
spherical, but soon become constricted at the base, and about the
same time the first trace of the sporangia can be seen. A sec-
tion of the young sporophyll shows that the centre of the promi-

f^*

Fig. 276. — A, Longitudinal section of the apex of a young fertile shoot, Xi6; B, apex
of the same, Xi6o; sp, young sporangiophore; x, apical cell.

nence already has formed the .young plerome which, as in the
ordinary leaves, joins that of the internode beneath. Just above
the base a cell may sometimes be detected, which is larger than
its fellows, and has a larger nucleus. From a comparison with
slightly older stages there is no doubt that this is the sporan-
gium mother cell, or more correctly the axial sporangial cell, as
the adjacent tissue also takes part in its further growth. This
axial cell now becomes separated into an inner and outer cell,
as in Botrychium. The outer cell divides again. The inner-

474

MOSSES AND FERNS

CHAP.

most cell of the axial row is the archesporium, and gives rise to
the sporogenous cells by repeated divisions, at first at right
angles to each other, later in all directions. Bower ((15), p.
497) thinks that all the sporogenous cells are not to be traced
back to the single archesporial cell, but that the inner of the
two cover cells also takes part in spore-formation. The exact
limits of the archesporium are difficult to follow, as the contents
of the sporogenous cells are not strikingly different from the

Fig. 277. — A, IvOngitudinal section of younp: sporangiophore, showing the primary
sporangial cell Uf), X260; B, C, longitudinal sections of young sporangia, X260.
The archesporial cells are shaded.

inner tapetal ones. These are derived from the cells adjacent
to the axial row, and from the cells of the latter just outside the
archesporium. The wall of the sporangium is mainly formed
from the cells adjacent to the axial row of cells. All the cells
grow and divide rapidly, so that the sporangium soon projects
strongly from the margin of the sporophyll, whose upper part
becomes broad and flattened, while the stalk increases but little
in diameter. The wall of the sporangium at first is three or
four cells thick. Finally it is reduced to but a single complete

XII

EQUISETINEJE

A7S

layer by the absorption of the others, but the remains of a sec-
ond layer can be made out in stained sections of the ripe sporan-
gium (Fig. 280, E). The vascular bundles of the sporophyll
divide, one branch running to each sporangium.

Of the two species studied by Bower, E. arvense and E. li-
mosnm, the latter showed more slender and strongly projecting
sporangia, but otherwise they were alike. E. tclmateia has
even more massive sporangia than E. arvense. The sporophylls

Fig. 278. — Longitudinal section of an older sporangium, X260. The nuclei are shown

in the archesporial cells.

form a regular cone at the apex of the fertile branch, and are
arranged in regular whorls, which vary in number in propor-
tion to the size of the cone. The top of the sporophyll is al-
ways polygonal in outline, owing to the lateral pressure of its
neighbours, and very often they are regularly hexagonal, but
this bears no relation to the number of sporangia, which usually
exceed in number the angles of the sporophyll.

Development of the Spores

The development of the spores in Eqnisetitm, while agree-
ing in many respects with that of the eusporangiate Ferns, shows
some peculiarities that are noteworthy, and as this offers one
of the best cases for studying spore-formation, it was somewhat

476 MOSSES AND FERNS chap.

carefully followed in E. fehuafcia. After the complete num-
ber of cells has been formed in the archesporium, and before
the tapetal cells are broken down, the sporogenous cells are di-
vided into groups which begin to separate from each other.
With the enlargement of the sporangium and the breaking down
of the inner tapetal cells these masses l^ecome isolated, and are
very easily removed from the sporangium (Fig. 240, A).
They usually consist of four cells, which in water swell up some-
what. In a fresh condition they appear quite colourless, but
the cytoplasm is densely granular. The nucleus is very large
and appears quite transparent with one or two distinct nucleoli.
In microtome sections of about the same age the numerous rod-
shaped chromosomes were very evident, but their number could
not be determined. The nucleolus is conspicuous, and on one
side, in a slight depression in the nuclear membrane were seen,
in some cases what were taken to be two centrospheres. The
latter were not always very evident, and the radiations which
are usually present about centrospheres, were not seen. From
the later investigations of Osterhout (i) upon E. liiiwsuin, it
is probable that the interpretation of these bodies as centro-
spheres was not warranted, as he failed to find centrospheres in
that species, and their presence in many other cases, where it
was supposed they existed, has been disproved.

Osterhout has also shown that the bipolar spindle, observed
in E. fahiiafeia is a secondary condition. In E. limosum, he
found that about the time the spirem-filament had completely
separated into the individual chromosomes, a change was ob-
servable in the cytoplasm surrounding the nucleus. Up to this
time the cytoplasm in material treated with the Flemming triple
stain shows the characteristic orange or brownish coloration.
The cytoplasni immediately around the nucleus now stains a vio-
let color, and is supposed to assume the character of kinoplasm.
This kinoplasmic zone increases in size, and gradually assumes
more and more the appearance of a dense net of delicate fibres —
the future spindle-fibres. These begin to extend outward into
the orange cytoplasm and converge at numerous points, so as
to form a number of conical bundles radiating from the nucleus.
There is thus developed a multi-polar spindle, and as the nuclear
membrane gradually disappears, the free ends of these spindle
fibres penetrate into the nuclear cavity and come in contact with
the chromosomes, which gradually arrange themselves into the

XII

EQUISETINE^

477

characteristic nuclear plate. The separate nuclear spindles
finally converge more and more, until finally they unite into a
more or less definite large bipolar spindle with the nuclear plate
at the equator (Fig. 279, C). Before the final division takes
place, the sporogenous cells become completely rounded off,
and are embedded in a mass of nucleated protoplasm (Fig.
280, A) derived from the tapetal cells, but also in part from
some of the archesporial cells which do not develop into spores.
Fig. 279 show^s the successive stages in the process. During

Fig. 279.— a, Group of four sporogenous cells of E. tehnatcia, X400; B, C, first mitosis
in E. limosum (after Osterhout) ; B, shows the multipolar spindle; D, E, second
mitosis in E. telmateia.

the division of the primary nucleus there is an evident cell plate
formed, but no division wall. During this first division there
is probably a reduction in the number of the chromosomes, as
in Osmunda. At any rate the number is evidently much smaller
during the metaphases of the second nuclear divisions (Fig.
279, D). The second divisions are the same as the primary
one,' and the planes of the two nuclear spindles may either be
parallel or at right angles (Fig. 279, D). In either case the
resulting nuclei arrange themselves at equal distances from the

478

MOSSES AND FERNS

CHAP.

centre of the cell, and the connecting filaments are formed be-
tween them. In the connecting spindles there is formed be-
tween each pair of nuclei a cell plate, which soon develops into a
definite cellulose membrane, and the spores separate completely.
It is probable that the definitive cell-wall is formed in the
same way as in the spore- formation of other plants (Mottier
(3), p. 7,2). The cell-plate formed at the equator of the spindle
in the later stages of division, is split into two layers which thus

Fig. 280. — A, Group of sporogenous cells, just before the final division into the spores,
embedded in the nucleated protoplasm formed from the disintegrated tapetum, and
sterile archespurial cells, X500; B, optical section of young spore, showing the
three membranes; in, the middle lamella, X500; C, an older spore, showing the
splitting of the outermost coat to form the elaters, X500; D, surface view of the
dorsal cells ofthe wall of a ripe sporangium, X150; E, section of the wall, show-
ing the remains of the inner layers of cells it), X250.

separate completely the two protoplasts. In the space between
the protoplasts, the new cell-wall is then laid down.

The young spore has at first a very delicate cellulose mem-
brane, which thickens, and later has separated from the outside
the ''middle layer" (Fig. 280, B, in), which in spores placed in
water lifts itself in folds from the underlying endospore. The
outer perinium seems to be unquestionably formed through the
agency of the nucleated protoplasm, in which the young spores

XII EQUISETINE^ 479

lie. It is at first a uniform membrane, closely applied to the
middle coat, but when placed in water it swells up and separates
completely from tlie exospore, or remains attached to it at one
point only, which marks the point of attachment of the elaters in
the ripe spores. The elaters arise from the epi spore by its
splitting spirally into four bands (Fig. 280, C), due apparently
to thickening along these bands, leaving thin places between,
which are finally absorbed. The outside of the elaters becomes
cuticularised. The ripe spores contain numerous chloroplasts,
which only are evident in the latest stages of development. In
E. arvense the formation of the sporangia begins nearly a year
before the spores are shed, and they are completely developed
during the preceding autumn. The growth of the fertile
branch and the scattering of the spores take place very soon
after growth begins in the spring. Whether in cold climates
E. tchnatcia behaves the same way I cannot state ; but in Cali-
fornia, where growth continues all the winter, the development
of the sporangia is gradual, and the fertile stems grow up and
scatter the spores as soon as they are ripe. The ripe sporangia
are oblong sacs, w^hose wall is composed for the most part of a
single layer of elongated cells, marked with spiral thickened
bands upon the dorsal surface and rings upon the ventral cells,
where the longitudinal slit by which the sporangium opens is
placed (Fig. 280, D, E). The internodes in the strobilus are
very little developed, but as the spores ripen there is a slight
elongation, by which the sporophylls are separated.

Classification

Milde ( i) divides the genus into two, Eq\iisctum^ (Eqnisefa
phanopora), in which the accessory cells of the stoma are on a
level with the surface of the epidermis; and Hippochcctc (E.
cryptopora), in which the stomata are sunk in depressions of the
epidermis. In the former group are two divisions, those which,
like E. arz'cnsc and E. tclinatcia, have the fertile and sterile
branches different, and those where they are alike, e. g., E. limo-
stiiJi (Fig. 280, A). Some species, e. g., E. pratcnse, have the
fertile stems at first colourless, but afterwards forming chloro-
phyll and developing branches. In Hippochcctc, which includes
among American species E. hiemalc, E. rohiistiim, E. variega-
^ Euequisetum, Sadebeck.

Fig. 281. — A, Equisetum Hmosum, XVil B, E. scirpoides, Xai

XII

EQUISETINEAi 481

turn and E. scirpoides (Fig. 281, B), the aerial branches are all
similar and often are quite unbranched. The foliar sheaths
show considerable variation. In the fertile stems of E. tel-
mateia (Fig. 266) they are extremely large and the ribs very
prominent, but the separate leaves are not all distinct at the
apex, but the sheath splits into a few very deeply cleft pointed
lobes. In the sterile shoots, however, and in all the stems of
most species, the teeth are very distinct and the foliar sheath
much shorter. The number of teeth varies from three in
E. scirpoides, to thirty or forty, or even more, in E. telmateia
and E. rohustum. In E, silvaticum the branches produce
whorls of secondary branchlets.

Sadebeck (8) recognises 24 species of Equisetum. The
largest forms occur in tropical America, where some species,
c. g., E. giganteum, reach a height of 3 to 12 metres, but are
relatively slender, the stem usually not exceeding two or three
centimetres in diameter, and requiring support from the shrubs
and trees among which it grows. E. Schaffneri is described as
having a stem about two metres in height with a thickness of
10 centimetres, but with a very large central cavity, so that it
is not very strong. In some of the larger species, e. g., E. gi-
ganteum, cones may be borne at the end of the lateral branches,
as well as at the apex of the main shoot.

Fossil EqnisetinecB'

The living genus Equisetum is represented in a fossil condi-
dition by a number of closely allied forms, perhaps generically
identical, and usually united under the name Equisetites. Be-
sides these, there are several types differing materially from
Equisetum, but nevertheless undoubtedly related to the living
forms. The most important of these fossil forms are the char-
acteristic Palaeozoic fossils belonging to the Calamitacese and
Sphenophyllacese. A further discussion of these forms will
be left for a later chapter.

Affinities of the EquisetinecB

The Equisetineae, as will be seen from the account of the
fossil forms, are a very ancient group, and their relation to the
other Pteridophytes somewhat problematical. The modern
31

482 MOSSES AND FERNS chap.

forms being so restricted in numljer and type, offer but partial
means of comparison ; still a comparison of these with the sim-
pler Filicineae does indicate some affinity between the two
groups, although, as might be expected, a very remote one.
Van Tieghem (6) has shown that the structure and arrange-
ment of the vascular bundles in the stem of Ophioglossum and
Eqnisctnui have much in common. As we have seen, the pro-
thallium is not essentially different in Equisctnm and the euspo-
rangiate Ferns, and the spermatozoids are closely like those of
the latter, and not at all like those of the Lycopodineae. This
latter point I believe to be one of great importance.

If the EquisetinCcT do come from a common stock with the
Ferns, they must have branched off at a very remote period,
long l:)efore the latter had become completely differentiated.
The very different importance relatively of the stem and leaves
in the two groups points to this, as well as the extremely dis-
similar character of the sporophylls. The genus Equisctnm
is evidently but a reduced remnant of a once predominant type
of plants which has been crowded out by the more specialised
Ferns and Spermatophytes. The presence of heterospory in
some fossil forms is interesting, but from what we know at
present it never developed to the same extent as in the other
groups of Pteridophytes.

CHAPTER XIII

LYCOPODINE^

The Lycopodine^e, though far exceeding in number the species
of Eqiiisetum, are inferior in number to the Ferns. Baker (2)
enumerates 432 species, of which 334 belong to one genus,
Sclaginella, while another, Lycopodium, has 94. A more re-
cent enumeration of the two genera (Pfitzer (2), Hieronymus
( I ) ) indicates a considerably larger number of species, Sclagi-
nella alone possessing approximately 500 species. Like the
Equisetineae they are abundant in a fossil condition, and it is
very evident that these ancient forms were, many of them,
enormously larger than their living representatives, and more
complicated in structure. The living species are mainly trop-
ical in their range, but Lycopodhnn has a number of species
common in northern countries, and a few species of Selaginella,
e. g., S. rupcsfris, have a wider range; but the great majority
of the species are found only in the moist forests of the tropics.
The gametophyte of the homosporous forms is known best in
Lycopodium. Our knowledge of it was based mainly upon
the important researches of Treub (2), but these have been
added to by Goebel (18) in the case of L. imindatum, and
more recently Bruchmann (5) and Lang (i) have succeeded
in finding prothallia of several European species, and we now
have a very satisfactory account of all but their earliest stages.

The gametophyte in its earliest condition, so far as is cer-
tainly known, develops chlorophyll, and this condition may be
permanent,^, g., L. ccrmmm, but other forms have a chloro-
phylless prothallium, and are saprophytic in habit, like Ophio-
glossnm. The germination of these forms is at present un-
known.

The sporophyte has the axis strongly developed, and the

483

484

MOSSES AND FERNS

CHAP.

Fig. 282. Part of a fruiting plant of Lycopodium clavatum, X i ; B, sporophyll, with
sporangium isp) of L. dendroideum, X12; C, cross-section near the base of an
aerial shoot of L. dendroideum, X 12.

xiii LYCOPODINEJE 485

leaves, though usually numerous, are simple in structure and
generally small. The genera are all homosporous except
Selaginella, which is very markedly heterosporous, and has the
gametophyte very much reduced and projecting but little be-
yond the spore wall.

CLASSIFICATION
Order I. Lycopodiales

A. Homosporece

I. Roots always present ; sporangia alike, simple, in the
axils of more or less modified leaves, which may form a distinct
strobilus, or may be but little different from the ordinary ones
both in form and position ; prothallia either green or colourless,
monoecious.

Family I. Lycopodiace^
Genera 2. — (i) Lycopodhmi; {2) Phylloglossuni

II. Roots absent ; vegetative leaves much reduced or well
developed; sporophylls petiolate, bilobed; sporangia pluriloc-
ular; gametophyte unknown.

Family II. Psilotace^
Genera 2. — (i) Psilotnm; {2) Tmesipteris

B. Heterosporece

Characters those of Family L, but spores always of two
kinds.

Family III. Selaginellace^

Genus i. ^ Selaginella

THE LYCOPODIACE^

The Gametophyte

The Lycopodiacese include the two genera Lycopodium
and Phylloglossuni, the latter with a single species, P. Drum-
mondii. The gametophyte is known in a number of species
of Lycopodium, and recently (Thomas (i)), has also been

486 MOSSES AXD FERNS chap.

described for PJiylloglossiiiii. Tlie first investigator who suc-
ceeded in obtaining the germination of the spores was De Bary
(i), who studied the earhest stages in the germination in L.
imindatnm, but was unable to obtain the later ones. About
fifteen 3'ears later Fankhauser found the old prothallia of L.
annotiniun (i), but our first complete knowledge of the pro-
thallium and embryo is due to the labours of Treub (2), who
examined most thoroughly several tropical species of Lyco-
podiuin. Goebel (18) succeeded in finding a number of pro-
thallia of L. iniindatnni which correspond very closely to L.
ccrnmini, the first species examined by Treub. Other Euro-
pean species have more recently been investigated by Bruch-
mann (5) and Lang (i).

The germination of the spores in L. ccrnuuin and L. in-
iindatuin is much like that of the homosporous eusporangiate
Ferns. The tetrahedral spores contain no chlorophyll, but it
develops before the first division wall is formed. This may
be either vertical or horizontal, or more or less inclined. The
two primary cells are nearly equal in size, but one of them ap-
pears to normally remain undivided. The other enlarges and
becomes divided by an oblique wall (Fig. 283, A), and func-
tions for some time as an apical cell, from which segments are
cut off alternately right and left. Usually each segnient is then
divided by a periclinal wall into a central and a peripheral cell.
Up to this point the germination of L. ccniuum corresponds
exactly with De Bary's observations upon L. iniindatuin. The
ovoid body formed at first Treub calls the "primary tubercle,"
and this does not develop directly into the complete prothal-
lium, but the apical cell ceases to form two rows of segments
and elongates so as to produce a filament in which for a time
only transverse walls are formed (Fig. 283, B). The base
of this filamentous appendage, however, later develops longi-
tudinal walls and forms a thickened cylindrical mass, which
is the beginning of the prothallium body. Sometimes, but not
usually, a second filamentous outgrowth is formed from the
primary tubercle, which may produce a second prothallial body.

The growth of the prothallium proper does not seem to
show a definite meristem, but at the summit are produced a
number of leaf-like lobes which seem to arise in acropetal suc-
cession, and the grov/ch may ])e considered, in a general way
at least, as apical. The individual lobes are usually two cells

XIII

LYCOPODINE^

487

thick, and like those of Eqnisetiim show a definite two-sided
apical cell. This apical growth later disappears and all trace
of it is lost in the older lobes. Rhizoids are produced only
in small numbers from the cylindrical prothallium body, and
are usually entirely absent from the primary tubercle, whose
peripheral cells are always occupied by an endophytic fungus
which Treub refers probably to the genus Pythiiim. We have
seen that similar fungus mycelia occur in the chlorophylless

■pic. 283. A, B, very young prothallia of Lycopodium cernuum. A, X250; B, X200.

*P Primary tubercle; C, an older prothallium of the same species with the first
antheridium i^^), X7S; D, a fully-developed prothallium (pr) with the young
sporophyte attached, X12; pc, protocorm; R, primary root; E, section through an
antheridial branch of the prothallium of L. phlegmaria, showing anthendia
(^) in different stages of development; par, a paraphysis, X180; F, surface view
of the top of an antheridium of the same species; o, opercular cell, X180; G, a
spermatozoid, X410; H, section of the archegonium of the same species, X180
(all the figures after Treub).

prothallium of Botrychmm, and Goebel found the same in L.
inundatum. While in the primary tubercle the fungus occu-
pies the lumen of the cells, as it penetrates into the body of the
prothallium it confines itself mainly to the intercellular spaces,
where its growth causes more or less displacement of the cells.
It does not, however, seem to penetrate into the meristematic
tissues at the summit.

The fully-grown prothallium of L. cermium is a small up-

488 MOSSES AND FERNS chap.

right cylindrical body, seldom, apparently, exceeding about
two mm. in height. The base is more or less completely
buried in the ground, and contains but little chlorophyll. The
summit is surrounded by the lobes already spoken of, and these
have somewhat the appearance of leaves crowning a short stem.
The whole structure of the prothallium recalls in some respects
that of Eqiiisctum, but differs in the important particular that
it is radially constructed, and is not dorsi-ventral.

Besides the type of prothallium found in L. ccrnmun, with
which L. iniindatum closely agrees, Treub has also studied the
very different prothallium of L. phlcgmaria, and others of sim-
ilar habit. Tliese are only known in their mature condition, in
which they are saprophytes, growing in the outer decayed lay-
ers of bark upon the trunks of trees. In this condition they
are extremely slender branched structures, totally different
from those of L. cermnun, both in form and in the complete
absence of chlorophyll. Like the prothallia of many Hymeno-
phyllacese, they multiply by special gemmae and apparently may
live for a long time. Like those of L. cermmm they are always
infected by an endophytic fungus.

Bruchmann (4) finds that there is a good deal of differ-
ence among the European species. L. clavatiim (Fig. 284, A)
and L. annotinum represent one type. The gametophyte is
subterranean, and in appearance not very different from that
of Botrychhim, although its manner of growth is of an entirely
different type. In the earliest stages observed, it was an up-
right, top-shaped body, the upper surface of which was some-
what depressed below the margin, which forms an elevated rim
about the central area. There is no proper apical growth, but
a zone of cells between the rim and the central area is meriste-
matic, and to the growth of this zone the future development of
the gametophyte is due. The whole of the central area is de-
voted to the formation of the reproductive organs, and consti-
tutes the "generative tissue," and like the similar tissue in Bo-
trychium, its cells are almost destitute of granular contents.
Outside the colourless generative tissue is a layer of dense stor-
age-cells, and outside of these a layer of tissue in which is an
endophytic fungus. Unicellular rhizoids occur iii consider-
able numbers upon the under surface.

The gametophyte of L. complanatum (Fig. 284, C) is also
subterranean, but quite dift'erent in form from that of L. clav-

XIII

LYCOPODINE^

489

attim, although the essential structure is much the same. It is
a fusiform structure, with a terminal mass of short, irregular
lobes covered with the reproductive organs. Between the ter-
minal generative portion and the sterile fusiform body of the
prothallium, there is a meristematic zone, corresponding to that
in L. clavatimt. The oldest reproductive organs are at the
centre of the generative area, the youngest are next the zone of
meristematic tissue.

L. Selago closely resembles L. phlegmaria in the structure
of the gametophyte, and there are similar paraphyses formed
among the reproductive organs.

L. inundatum, as was pre-
viously shown by Goebel,. be-
longs to the type of L. ccr-
miiim, and Phylloglossurn
(Thomas (i)) seems to be
very much like L. cernuum,
in the structure of the game-
tophyte.

The gametophytes of all
species are normally dioe-
cious, but the antheridia
usually develop first.

The Sexual Organs

Fig. 284. — A, Lycopodium clavatum, gameto-
phyte, X3; B, L. annotinum, old game-
tophyte, with young sporophytes, sp, at-
tached, X3; C, gametophyte of L. com-
planatum, X3 (after Bruchmann).

The sexual organs of all
investigated species of Lyco-
podium are very similar, and
resemble those of the eusporangiate Ferns and Eqiiisetum,
As in these forms the antheridium mother cell divides first by a
periclinal wall into an outer and inner cell, the latter giving
rise immediately to the sperm <:ells. In the outer cell the divi-
sions are much like those in Marattia, but the opercular cell
does not become detached as in these, but is broken through
as in the Polypodiacese. In L. phlegmaria the outer wall is
often in places double, as not unfrequently is the case in the
Ophioglossaceae. The spermatozoids are almost straight ob-
long bodies with two cilia, like those of the Bryophytes (Fig.
283, G). The vesicle, which usually remains attached to the
spermatozoids of most Archegoniates, here is almost always

490 MOSSES AND FERNS chap.

free and often remains within the sperm cell after the escape
of the spermatozoids.

The archegonium in most species of Lycopodiiim differs a
good deal from that of the other Pteridophytes, especially in
the large number of neck canal cells that are usually found.
The cells of the axial row may be as many as ten in L. annoti-
nitin, and in L. coinplanatuin Miss Lyon (3) found 14-16 cells,
which in some cases had two nuclei in each cell, a condition
which is also found in L. phlcgmaria. L. ccrnnum, however,
according to Treub, has but a single neck canal cell.

In the remarkably large numl^er of canal cells, as well as
in the occasional development of five instead of four outer cell-
rows in the neck (Bruchmann (4), p. 34), Lycopodiuui un-
doubtedly resembles more nearly the typical Bryophytes than
does any other of the Pteridophytes.

The Embryo (Trciib (2); Bruchmann (-/))

Treub has traced the development of the embryo in L.
phlcgmaria through all its stages, and has shown that L. ccr-
nnum corresponds closely to it, and Goebel's investigations
upon L. inundatum show that this species does not differ essen-
tially from the others. The first division in the embryo is
transverse, and of the two primary cells the one next the arche-
gonium remains undivided, or divides once by a transverse
wall and forms the suspensor, which is characteristic of all in-
vestigated Lycopodinese, while the lower cell alone gives rise
to the embryo proper. In the embryonal cell the first wall is
a somewhat oblique transverse one, which divides it into un-
equal cells. In the larger of these a wall forms at right angles
to the primary wall (Fig. 285, A), and this is soon followed
in the smaller cell by a similar one, so that the embryo is di-
vided into quadrants. Of these the two lower form the foot,
while of the upper ones in L. phlcgmaria, the one formed from
the larger of the two primary cells (moitie convexe of Treub)
produces the cotyledon, the other the stem apex. The primary
root, which in Lycopodium arises very late, originates from
the same quadrant as the cotyledon.

In L. cernuum, while the early divisions correspond exactly
with those of L. phlcgmaria, the further development of the
embryo shows some noteworthy differences. As in that

XIII

LYCOPODINEM

491

species, the two lower quadrants form the foot, which here
remains completely buried within the prothallium. From the
upper part of the embryo is next developed what Treub calls
the "protocorm." This is a tuber-like organ (Fig. 283, D,

Fig. 285. — Embryogeny of Lycopodium phlegmaria (after Treub). st, Stem; cot,
cotyledon; susp, suspensor. A, X315; B, X235; C, X235; D, Xi75-

pc),, from which the leaves and stem apex are subsequently
developed. The cotyledon arises from the summit of the pro-
tocorm, and is followed by a number of secondary kaves which

492 MOSSES AND FERNS chap.

form successively from a group of meristematic cells, which
usually develop into the permanent apex of the stem. About
the time that the stem apex becomes recognisable as such, the
first root appears as a surface outgrowth of the protocorm,
and strictly exogenous in origin. Not infrequently the end
of the primary root gives rise to a tubercle similar to the proto-
corm.

An interesting case was seen by Treub, where, apparently
by a longitudinal division of the young embryo, two embryos
were formed, much as is normally the case in some Gymno-
sperms.

On comparing the two types of embryo found in L. phleg-
maria and L. cermium, the main differences are the almost
complete absence of the protocorm and greater development of
the suspensor in the former. L. inundatum, as might be ex-
pected, corresponds closely in the structure of the young sporo-
phyte to L. ccrnuum.

Corresponding with the late appearance of the roots is the
late development of the vascular bundles, which, according to
Treub, are often quite absent from the cotyledon and even
occasionally from the second leaf. The protocorm of L. cer-
uiiiim and L. inundatum Treub regards as the remains of a
primitive structure originally possessed by the Pteridophytes,
which replaced the definite leafy axis found in the more special-
ised existing forms.

Phylloglossuni, which has sometimes been regarded as the
most primitive of existing Pteridophytes, resembles closely the
young sporophyte of Lycopodium ccrnuum.

Bruchmann states ((4), p. 38) that the fertilised egg en-
larges very much before the first division w^all is formed, differ-
ing in this respect from Sclaginclla, and more resembling Ma-
ratfia or Botrychium. The first division is transverse. The
larger of the two cells, lying next the archegonium-neck, forms
the suspensor, and the smaller one develops into the embryo
itself.

Both L. clavahim and L. annotimim differ from the species
studied by Treub in the late development of the leaves (Bruch-
mann (4), p. 46). Moreover, in these species there are two
opposite cotyledons as in Sclaginclla.

The development of the young sporophyte is extraordi-
narily slow, and Bruchmann states that it sometimes does not

XIII

LYCOPODINE^

493

appear above the surface of the earth until several years have
elapsed. The leaves developed upon these subterranean shoots
are rudimentary. Sometimes more than one sporophyte is
borne by the prothallium (Fig. 284, B). The differentiation
of the vascular cylinder begins about the time that the root
breaks through the prothallial tissue. The hypocotyledonary
part of the stele is diarch, but higher up four or five protoxylem
groups are developed.

Fig. 286. — A, Lycopodium pachystachyon, XHl B, L. volubile, showing the two forms

of leaves, X2%.

The Adult Sporophyte

In all species of Lycopodium the sporophyte possesses an
extensively branched stem, which may be upright, as in L.
cernuum, or extensively creeping, as in L. clavatum and other
species, where the main axis is a more or less completely sub-
terranean rhizome with upright secondary branches. In the
tropics some species are epiphytes. The leaves are always
simple, and of small size. Each leaf has a single median vas-
cular bundle, which does not extend to the apex. The ar-
rangement of the leaves is usually spiral, and they are uni-
formly distributed about the stem, and all alike ; but in a few
species, e. g., L. complanatum and L. volubile, they are of two

494

MOSSES AND FERNS

CHAP.

kinds and arranged in four rows, as in most species of Sclagi-
ncUa. The branching of the stem is either dichotomous or
monopochal. The roots, which are borne in acropetal succes-
sion (Bruchmann found also in L. innndatiim adventive roots),
branch dichotomously, hke those of Isoctcs. The sporangia
are borne singly, in the axils of the sporophylls, which may
differ scarcely at all from the ordinary leayes (L. scIas[o, L.
htcidnltmi), (Fig. 287), or the sporophylls are different in
form and size from the other leayes and form distinct strobili,

Fig. 287. — Lycopodium selago. A, Longitudinal section of the stem apex, X120; F, F,
young leaves; i, i, initial cells; PI, plerome; B, surface view of the stem apex,
showing the group of initial cells, X260; C, longitudinal section of the root-tip; d,
dermatogen; Ph, periblem; PI, plerome; Cal, calyptrogen; h, h, root-hair initials,
X 120 (all the figures after Strasburger).

which are often borne at the end of almost leafless branches
(Fig. 282).

None of the inyestigated species of Lycopodhnn show a
definite initial cell at the apex of the stem, and Treub ( (2), V)
was unable to determine positiyely whether such a one exists in
the embryo. In L. phlcgniaria he describes and figures em-
bryos, where a single prismatic apical cell is apparently pres-
ent, but in others the presence of such a cell was doubtful, and
in L. ccrnuiDu in no case did he find any eyidence of a single
initial.

The yegetatiye cone of the mature sporophyte is usually

XIII LYCOPODINE^ 495

broad (Fig. 287) and only slightly convex. Its centre is occu-
pied by a group of similar initial cells, which in L. selago,
according to Strasburger ((10), p. 240), usually show two
initials in longitudinal section (Fig. 287, i). From these in-
itials are cut off lateral segments which, by further periclinal
and anticlinal walls, produce the epidermis and cortex, and sec-
ondarily the leaves. Periclinal walls also are formed from
time to time in the initial cells, by which basal segments are
cut off, which produce the large central plerome cylinder.

The leaves arise as conical outgrowths near the stem apex,
and owe their origin to the three or four outer cell layers of the
growing point. The separation of the epidermis does not oc-
cur until the leaf has formed a conspicuous conical protuber-
ance. The differentiation of the procambium in the young
leaf begins early, and the strand joins the central procambial
cylinder of the stem, which, however, is quite independent
of the leaf-traces. Each young leaf -trace joins an older one
at the point of junction with the stem cylinder, and thus the
complete stem possesses two systems of vascular bundles, the
strictly cauline central cylinder, and the system of common
bundles formed by the united leaf-traces.

The first elements of the vascular bundles to become recoof-
nisable are spiral tracheids, both in the stem and leaves, and
these are followed in the former by the much wider scalari-
form tracheids that occupy the central part of the tracheary
plates in the fully-developed bundles.

The fully-developed central cylinder of the stem (Russow
(i), p. 128; De Bary (3), p. 281 ; Strasburger (11), vol. iii.,
p. 458; Strasburger, /. c, p. 460; Van Tieghem (5), p. 553)
is undoubtedly to be considered as a group of confluent vascu-
lar bundles or as gamostelic. The oval or nearly circular cross-
section (Fig. 288, A) is sharply separated from the surround-
ing ground tissue by a clearly-marked endodermis, within
which is a pericycle which may be only one cell thick, but is
usually several-layered. According to Strasburger this peri-
cycle does not properly belong to the central cylinder, but is
of cortical origin. The cutinised band (''radial folding") of
the endodermal cells is only observal^le in the younger stages,
as later the whole wall of the endodermal cells become cutin-
ised. This cutinisation extends also through a number of the
succeeding cortical layers. The rest of the cortical region is

496

MOSSES AND FERNS

CHAP.

in most species occupied by elongated sclerenchyma cells, with
no intercellular spaces.

The central vascular cylinder contains, as is well known,
several, usually transversely placed, tracheary plates, alter-
nating with phloem masses, and surrounding these a varying
amount of parenchyma. In upright species the tracheary
plates are often more or less completely confluent, and in cross-
section have a somewhat star-shaped outline. In the dorsi-
ventral stems the tracheary plates are quite separate and per-
fectly transverse in position. Their outer angles are occupied

D.j,

•

• •

1 ^*

Fig. 288. — A-D, Lycopodium volubile ; A, transverse section of the stem, X18; /, leaf-
base; B, tissues of the central part of the stem, X about 200; C, sieve-tube show-
ing lateral sieve-plates, X about 600; D, section of the wall of a sieve-tube; E,
section of the leaf of L. lucidulum, X35-

by the small primary spiral or annular tracheids, from which
the centripetal formation of the large scalariform elements
proceeds exactly as in the leptosporangiate Ferns. The mass
of tracheary tissue is compact, and contains no parenchyma-
tous elements. According to Strasburger the oblique end
walls of the large tracheids show the same elongated pits as the
lateral walls, but in no cases could any communication between
adjacent tracheids be demonstrated. Each tracheary mass is

XIII LYCOPODIMEM

497

surrounded by a single layer of parenchyma, whose inner cell
walls show bordered pits, like those of the adjacent tracheids.

The phloem masses are, in the arrangement and develop-
ment of the parts, very like the xylem, and the formation of
the sieve-tubes begins at the outer angles and proceeds centrip-
etally. The large sieve-tubes in L. vohihile (Fig. 288, C) are
conspicuous, appearing nearly empty, and with delicate, colour-
less walls. Upon their lateral faces are numerous sieve-plates,
which in the smaller species are not easily demonstrated.

Where the branching is monopodial, the young branches
arise laterally close to the growing point, but without any re-
lation to the leaves. Where, however, as in L. selago (Stras-
burger (10), p. 242), there is a genuine dichotomy, it is in-
augurated by an increase in the number of initial cells, which
is then followed by a forking of the apex of the plerome cyl-
inder, and the two resulting branches are exactly alike. Inter-
mediate conditions between a perfect dichotomy and true mon-
opodial branching occur. In these there is a true dichotomy,
but one branch is stronger than the other, and continues as the
main axis, while the weaker one is pushed to one side and looks
like a lateral shoot. Bruchmann has described certain "pseu-
do-adventive" buds, which are young branches arrested in their
development at a very early stage, which may later develop.
Strasburger (7) has found adventive buds in L. aloifolium, L.
verticillatwii, L. taxifoliiim, and L. reflexiim, which possibly
may be of the same nature.

The Leaf

The leaves of all species of Lycopodium are relatively small,

and are usually lanceolate in outline with broad sessile base.

The margins of the leaves are often serrate, and in all cases

the leaf is traversed by a simple midrib, which, as already

stated, does not reach to the apex. Their arrangement varies,

even in the same species, and upon the same shoot. Thus in

L. alpinnm (Hegelmaier (i), p. 815) the leaves are regularly

arranged in pairs which arise simultaneously; in L. selago

they are usually in true whorls of four or five. The latter,

however, often shows a spiral arrangement of the leaves > with

a divergence of two-ninths, less often two-sevenths. In other

species, e. g., L. complanatum, L. vohihile (Fig. 286, B), the
32

498 MOSSES AND FERNS chap.

leaves are dimorphous and arranged in four ranks, like those
of most species of Selaginella.

The structure of the vascular hundle of the leaf is simple.
It is concentric in structure, with the central part composed
of a small number of spiral and annular tracheids, and the
peripheral portion made up of parenchyma, with a circle of
scattered narrow sieve-tubes. A definite endodermis cannot
be demonstrated. In the species with the leaves all alike both
surfaces bear stomata, but in those with decussate leaves the
greater part of the upper surface is destitute of them.

The Root

The roots of Lycopodium arise, as in other Pteridophytes,
in acropetal succession, but with no relation to the position of
the other organs. According to Bruchmann adventive roots
may arise in L. imindatuin, but they have not been observed
in other forms. L. sclago (Strasburger (lo), p. 259) may
serve to show the characters of the root in the genus. The
meristem of the apex is clearly differentiated into the initials
of the different primary tissues (Fig. 287, C). The dermat-
ogen ((/) completely covers the apex of the growing point as
a single layer. The periblem (pb) is three cells thick; the
plerome (pi) terminates in a group of special initials. As in
the stem, the plerome alone forms the central cylinder, the peri-
blem giving rise only to the cortex, and the structure of the
mature root corresponds closely to that of the stem, except for
the presence of the root-cap, which has its own initial group of
cells (calyptrogen, cal). From the older dermatogen cells are
derived, by special walls, the mother cells of the root-hairs (h).

Van Tiegliem ((5), p. 553) states that the secondary roots
arise from the pericycle instead of from the endodermis, as in
other Pteridophytes; but Straslxirger claims that the so-called
pericycle of Lycopodiiiui is really cortical, and does not belong
properly to the central cylinder, so that this difference is only
apparent. The endodermis itself is not readily recognisable
on account of the complete cutinisation of the walls.

The origin of the root-hairs is somewhat peculiar. From
the base of each dermatogen cell a wedge-shaped cell is cut off
(Fig. 287, C, h), and this afterwards is divided into two sim-
ilar cells, each of which grows out into a unicellular hair.
Thus the root-hairs are found in pairs.

XIII

LYCOPODINE^

499

The roots always normally branch dichotomously, as in
Isoetes, and the successive divisions usually are in planes at
rio-ht aneles to each other. As in Isoetes, the process is in-
augurated by a broadening of the apex of the root, which is
followed by a forking of the plerome and a subsequent division
of the other histogenic tissues.

The structure of the mature root (Russow (i)) in L.
clavatum, L. alpinum, and
mo'St species examined, is
much like the stem. The
hexarch to decarch fibrovas-
cular cylinder is radial in
structure, the xylem plates
often united at the centre, so
that in cross-section they
present a more or less regu-
lar stellate form. In L.
selago and L. imindatiim,
according to Russow, the
xylem is diarch and the two
masses united into a single
one, which is crescent-shaped
in section, with the phloem
occupying the space between
the extremities. As in the
stem the primary tracheids
are narrow annular and
spiral ones, and the large
secondary ones scalariform.

GemmcE

Fig. 289. — A, End of a shoot of Lyco-
podium hicidulum, with gemmae
(k) and sporangia (sp), X2; B, a
single bulblet, X4; C, germinating
bulblet of L. selago (after Cramer),
X4; >*, the primary root.

Special bulblets or gem- -
mse are formed regularly in
a number of species of Ly-
copodmm, and have been
the subject of several special

investigations (Cramer (i); Hegelmaier (i); Strasburger
C7)). These in L. lucidiihim (Fig. 289, A, k) are flattened,
heart-shaped structures composed of several thickened fleshy
leaves, and formed apparently in the axils of somewhat modi-

500 MOSSES AND FERNS chap.

fied stem leaves, from which they readily separate when fully
grown. The axillary origin of the bulblets is only apparent;
they are really, so far as can be determined, similar in origin
to the ordinary branches, and formed without any relation to
the leaves. Before the bulblet becomes detached, the rudiment
of a root can be made out at the base, and as soon as it falls off
and comes in contact with the earth the root begins to grow and
fastens the bulblet to the ground (Fig. 289, C). The axis of
the bulblet, which at first is very short, rapidly elongates, and
the leaves formed up it have the characters of the ordinary
ones. As the leafy axis develops the fleshy leaves of the bulb-
let lose their chlorophyll completely and finally decay.

Hegelmaier describes mucilage ducts in the stem and leaves
of L. inundatum and some other species, which are not unlike
those found in Angiopteris.

The Sporangium

The most recent and accurate account of the structure and
development of the sporangia of the Lycopodine?e is that given
by Professor Bower in his memoir upon this subject (15).
His investigations include a number of species of Lycopodium,
and the following account is taken mainly from his memoir.
The results of his investigations show that there is much more
variety shown than was before supposed, both in the form of
the sporangium itself and in the mode of origin and number of
the archesporial cells.

In L. sclago the sporangium originates upon the upper
surface of the sporophyll close to its base, and in radial section
the young sporangium appears to originate from a single cell ;
but this is really only one of a transverse row of cells, all of
which participate in its formation. Each cell of this primary
row divides first into a large central cell (Fig. 290, C, x) and
(in radial section) two peripheral ones. The central cell next
by successive periclinals forms a row of three cells, of which
the middle one is the archesporium, which, judging only from
radial sections, seems to consist only of a single cell; but com-
paring with the radial section a tangential one, it is seen that
the archesporium really consists of a row of similar cells (Fig.
290, F). The growth in the upper part of the sporangium is
stronger than below, so that a distinct, although short stalk is

XIII

LYCOPODINE^

501

Fig. 290. — A, Plant of Phylloglossum Drummondn, X about 3 (after Bertrand). sp.
Sporangia; R, roots; T^, protocorm; T^, secondary protocorm; B, longitudinal sec-
tion of the young strobilus of the same, showing the initial cell (0, young leaves
(/', /"), and young sporangium (^/j), X240; C-E, young sporangia of Lycopodium
selago, radial sections, X22S; F, tangential section of the same; G, radial section
of young sporangium of L. clavatum (Figs. B-G after Bower).

502 MOSSES AND FERNS chap.

formed. The archesporial cells rapidly divide, but show little
regularity in the divisions. All of the resulting cells separate
and produce four spores in the usual manner. The wall of the
mature sporangium consists regularly of three layers of cells,
of which the innermost is the tapetum. The tapetum bound-
ing the lower part of the archesporium is derived from the
cushion-like group of cells below it, to which Bower gives the
name "sub-archesporial pad." The tapetum does not become
disorganised, as in most Ferns and Equisctuui, but remains
as part of the sporangium wall. The fully-grown sporangium,
as in all species of Lycopodhun, is kidney-shaped.

Among the numerous other species investigated by Profes-
sor Bower, L. clavatiini represents the type most widely re-
moved from L. sclago. The differences between the two are
summarised by Professor Bower as follows :

"i. The sporangium is similar in position and in general
form to that of L. sclago, but its body is more strongly curved.

"2. The archesporium here consists of three rows of cells,
each row being composed of a large number (about twelve)
of cells ; thus the extent of the archesporium is much greater
than in L. sclago, occasional additions to it seem to be made
by cells cut off periclinally from the superficial cell at an early
stage.

''3. The tapetum is similar in origin to that in L. sclago.

"4. The sub-archesporial pad is much more developed, and
is at times extended as processes of tissue which penetrate the
sporogenous mass for a short distance.

''5. The stalk of the sporangium is much shorter and
thicker than in L. sclago.

"6. Arrested sporangia are frequently present, and may be
found either. at the base or apex of the strobilus.

"y. L. inundatuin may be looked upon as an intermediate
link between the type of sporangium of L. sclago and that of
L. clavatuju, both as regards form of the sporangium and com-
plexity of the archesporium."

Phylloglossum

The other genus of the Lycopodiacere contains ])ut the single
species P. DriDnmondii, from Australia and New Zealand.
This curious and interesting little plant has been carefully in-

XIII LYCOPODINE^ 503

vestigated by Bower (5) and Bertrand (3), and the former
regards it as the most primitive in structure of all the living
Pteridophytes.

The sporophyte resembles in an extraordinary degree the
young sporophyte of Lycopodium, especially L. ccrmnun. It
grows from a small tubercle (protocorm), which is regarded as
homologous with the same structure in the embryo of Lyco-
podium. This protocorm in small plants produces only sterile
leaves — from four to twenty — and a small number of roots,
often only a single one. In more vigorous plants a smaller
number of sterile leaves is formed, but the apex of the proto-
corm grows into an elongated axis, bearing a single small stro-
bilus at the apex (Fig. 290, A). The structure of the latter
is essentially as in Lycopodium. The roots are produced exog-
enously, as in the Lycopodium embryo, and are in structure
much the same. All of the tissues are very simple, and none
of the organs show a single apical cell, except possibly the apex
of the strobilus, w^here such a single initial seems to be some-
times present (Fig. 290, B, /). At the end of the growing
season a new protocorm is formed. This arises directly from
the apex of the old one, where no strobilus is developed, but in
the latter case grows out upon a sort of peduncle from near the
base of one of the leaves. The development of the sporangia
is essentially the same as in L. selago (Fig. 290, B).

The anatomy of the vegetative organs has been carefully
studied by Bertrand, and corresponds closely to that of Lyco-
podium, but the tissues are simpler. In the axis which bears
the strobilus there are about six xylem masses arranged in a
circle, but there is no definite endodermis limiting the central
cylinder. The root-bundle is diarch.

Recently the gametophyte of Phylloglossum has been dis-
covered and described by Thomas ( i ) . In its main features
it agrees with that of Lycopodium cermmm, having abundant
chlorophyll, and having much the same general structure. The
sexual organs and embryo also resemble those of L. cermmm.

Bertrand states that M. L. Crie found that the spores ger-
minated readily, and produced a colourless prothallium like
that of the Ophioglossaceas, both in form and in the structure
of the sexual organs, but that the spermatozoids are biciliate.

These observations do not agree with the results of
Thomas's investigations. The latter observer thinks that per-

504 MOSSES AND FERNS chap.

haps Crie may have obtained only the early stages of the pri-
mary tubercle. The differences between Phylloglossiiin and
Lyco podium do not seem sufficient to warrant the establishment
of a separate family, the Phylloglossese, as Bcrtrand proposes.

The Psilotace^ {Pritzcl (/))

The Psilotace?e include the two evidently related genera
Psilotiun and Tmcsiptcris, the former with two extremely vari-
able species (Baker ( i ) ) , the latter with but a single one. All
the species are tropical or sub-tropical, Psilotum being found in
all the warmer parts of the world; but Tmcsiptcris is confined
to Australia, New Zealand, and parts of Polynesia. The pro-
thallium is quite unknown in both genera, but the development
and anatomy of the sporophyte of both are now pretty well
known. The sporophyte (Bertrand (i, 2); Bower (15);
Solms-Laubach (i)), which in its mature condition is quite
destitute of roots, grows either upon earth rich in humus
{Psilotum triquctrum), and is evidently more or less sapro-
phytic, or it may be an epiphyte. Tmcsiptcris grows upon the
trunks of tree-Ferns, and Bertrand states that it is a true para-
site, which, however, like Viscum or Phorodendron, has not
entirely lost its chlorophyll. The plant always consists of two
parts, a lower portion consisting of branched root-like rhizomes,
which take the place of roots, and aerial green branches which
ramify dichotomously. The branching is especially marked in
Psilotum, much less so in Tmcsiptcris. The leaves are small
and scale-like in Psilotum, larger and lanceolate in Tmcsiptcris.
The sporangia (or synangia) are bilocular in the latter, trilocu-
lar in Psilotum and in both cases borne upon a smaller bilobed
sporophyll.

The development of the sporophyte has been carefully
studied by Solms-Laubach ( i ) , who discovered that it multi-
plied rapidly by means of small gemm?e (Fig. 292, k) produced
in great numbers upon the subterranean shoots. These buds or
bulblets are small oval bodies, but one cell in thickness, and
showing usually a definite tw^o-sided apical cell. Their cells
are filled with starch, and they sometimes remain a long time
dormant. These buds may produce others, but usually from
each one is produced one, or sometimes more, elongated shoots,
which develop into subterranean branches like those from

XIII

LYCOPODINE^

505

which the bud was originally produced. The young plant
arising from the gemma is at first composed of uniform paren-
chyma, but in the later formed portions a simple vascular bundle
is finally developed. No definite apical cell can be detected in

Fig. 291. — Part of a vigorous plant oi -^Psilotum triquetrum, about J^ ; u, u, Sub-
terranean shoots; a, a, the bases of aerial branches; sy, synangia; B, branch with
two mature synangia, slightly enlarged; C, a single opened synangium, showing
the two lobes of the sporophyll below it (after Bertrand).

the earlier stages, but later each branch of the rhizome shows
a pyramidal initial cell, much like that in the Ferns, but less
regular in its divisions, and it is not possible to trace back all
the tissues with certainty to this single cell. The branching is
a true dichotomy, but is not brought about by the division of

5o6

MOSSES AND FERNS

CHAP.

the original apical cell, but this becomes obliterated previous
to the formation of the two branches, and two new initial cells
are formed quite independently of it.

The tissues of the Psilotace?e are quite simple (Russow ( i),
Pritzel (i). Ford (i)). The most recent account is by Miss
Ford, who has made a very complete study of the tissues of
Psilotuin triquctrum.

The surface of the aerial shoot is strongly ribljed (Fig. 293,
A) in the stouter portions, but nearly triangular in section

Fig. 292 — Psilotum triqtietrum. A, Fragment of a subterranean shoot with a
young gemma {k), X120; B, longitudinal section of the apex of a subterranean
shoot, X185; C, transverse section of the apex of a subterranean shoot in the act
of forking, x, x, the apical cells of the two branches, X 185 (all figures after
Solms-Laubach) .

nearer the apex. Within the epidermis, in which are numerous
stomata, there is a zone of outer cortical cells, containing nu-
merous chloroplasts, and constituting the principal assimilating
tissue. The cells of this zone are irregular in outline, with
numerous intercellular spaces, like the mesophyll of many
leaves. Inside this assimilative cortex is a zone of scleren-
chyma forming the principal mechanical tissue of the shoot.
Within this zone is a mass of thin-walled parenchyma, bounded

XIII

LYCOPODINE^

$07

internally by the endodermis which limits the central cylinder.
Miss Ford finds that with proper treatment, the endodermis
can be readily differentiated, although ordinarily its presence
is not evident.

The central cylinder, or stele, has its axis composed of a
mass of sclerenchyma about which the radiating xylem-masses
form a more or less regular star-shaped mass, wdien seen in
transverse section. The number of xylem masses varies from
3 to 10. The protoxylem, composed as usual of narrow spiral
tracheids, occupies the points of the star-shaped section, the
larger secondary tracheids being developed centripetally. The
latter are scalariform. The phloem is very poorly differenti-
ated, and its boundaries are impossible to determine exactly.
Larger elements, probably representing sieve-tubes, are present

Fig. 293. — ^A, Section of the stem of Psilotitm tnquctnim, X20; B, part of the central
cylinder, X150; C, section of the stem of Tmesipteris tannensis, X20; D, part of
the central cylinder, X150.

but neither well-defined sieve-plates nor callus could be dem-
onstrated. Between the endodermis and protoxylem are sev-
eral layers of pericycle cells. In Psilohiiu the leaves have no
vascular bundle; in Tmesipteris a single bundle traverses the
leaf, as in Lyeopociinm.

The structure of the stem in Tmesipteris (Fig. 293, C) is
much like that of Psilotnm, but is simpler. There are 3 to 5
xylem-masses which are much less symmetrically arranged
than in Psilotnm. The leaves, however, possess a well-devel-

So8

MOSSES AND FERNS

CHAP.

oped vascular bundle, which is continued hito the stem as a
leaf-trace, and joins the axial cylinder.

The Sporangium (Bozver (13))

There has been much disagreement as to the morphological
nature of the sporangiophores of the Psilotaceae. The two
chief views are the following : ( i ) That the whole sporangio-
phore is a single foliar member; (2) that it is a reduced axis

Fig. 294. — Tmesipteris tannensls. A, Radial section of the young sporangiophore,
X112; sy, the young synangium; B, similar section of an older sporangiophore,
X112. The archesporial cells are shaded. C, Fully-developed synangium, show-
ing its position between the two lobes of the sporophyll, X3; D. a longitudinal sec-
tion of the synangium, showing the two loculi (all the figures after Bower).

bearing a terminal synangium and two leaves. The recent very
careful researches of Bower upon the origin of the sporangio-
phore and synangium confirm the former view. He describes
the development in Tmesipteris as follows : 'The apical cone

XIII LYCOPODINE^ 509

of the plant is very variable in bulk. ... In the large as well as
the small specimens a single initial is usually present, but its seg-
mentation does not appear to be strictly regular, and it is diffi-
cult to refer the whole meristem to the activity of one parent
cell. . . . When a leaf or sporangiophore is about to be formed,
certain of the superficial cells increase in size, and undergo both
periclinal and anticlinal divisions so as to form a massive out-
growth, the summit of which is occupied, as seen in radial sec-
tion, by a single larger cell of a wedge-like or prismatic form. . . .
In these early stages I find it impossible to say whether the part
in question will be a vegetative leaf or a sporangiophore, and
even when older it is still a matter of uncertainty. . . . Those
which are to develop as sporangiophores soon show an increase
in thickness, while they grow less in length ; an excrescence of
the adaxial surface soon becomes apparent (Fig. 294, A, sy),
in which the superficial cells are chiefly involved. . . . The super-
ficial cells at first form a rather regular series, which may be
compared with the cells which give rise to the sporangia in Lyco-
podiuin clavatiun, or in Isoctes: they undergo more or less regu-
lar divisions, which, however, I have been unable to follow in
detail : a band of tissue some four or more layers in depth is thus
produced. About this period certain masses of cells assume
the characters of a sporogenous tissue : but though they can be
recognised as such by the character of the cells, it is extremely
difficult to define the actual limits of these sporogenous masses."

In Tmcsiptcris there are normally two masses of sporog-
enous tissue corresponding to the two loculi in the mature synan-
gium; in Psilotiim, which correspond closely with Tmesipteris
in other respects, there are three. Whether additions are made
to the sporogenous tissue from cells outside the original arch-
esporium was not determined with certainty, but Professor
Bower thinks it not improbable. In PsiloHim the young arch-
esporium is more clearly defined than in Tmcsiptcris, and it
seems not unlikely that each sporogenous mass is referable to the
division of a single primary archesporial cell. In both genera
some of the sporogenous cells do not develop spores, but simply
serve for the nourishment of the others, as in Eqiiisctiim.

The fully-developed synangium has the outer walls of the
loculi composed of a single superficial layer of large cells, be-
neath which are several layers of smaller ones (Fig. 294, D).
The cells composing the septa are narrow tabular ones, with

510 MOSSES AND FERNS chap.

firm woody walls marked by numerous pits. Occasionally the
septum is partially absent and the loculi are thus thrown more
or less completely into communication. The spores are usually
of the bilateral form, like the microspores of Isoctcs, but may
also be of the tetrahedral type.

Bower regards the whole synangium as homologous with
the single sporangium of Lycopodhiin, and also calls attention
to its resemblance to the sporangium of Lepidodendron, with
which the Psilotacece also show resemblances in the structure
of the stem.

The Affinities of the Psilotacece (Bozver {21), Ford (i),

Seott {!))

\\niile the Psilotace?e are usually united with the Lycopods,
there has l^een of late a tendency to remove them from this class,
and to assume a somewhat near affinity with the fossil Spheno-
phyllales, whose relationships are usually considered to be with
the Equisetales. The undoubted anatomical resemblances be-
tween the PsilotacCcX and Lycopodiacese cannot be overlooked,
and the question then remains whether these resemblances are
anything more than analogies.

The anatomy of the smaller shoots of the Psilotacea^ un-
doubtedly recall the stem-structure of SphenophyUuin. and there
seems to be also important points of resemblance in the sporan-
gial structures. (Bower (21), Thomas (3)).

Miss Ford ((i), p. 603), whose work on Psilotum is the
most recent, considers the Psilotace?e to be much reduced forms,
probably owing to their saprophytic habit. They are ''some-
what closely allied to the fossil group of the Sphenophyllales."

The Selaginellace^

Unlike the FilicinCcX, the heterosporous Lycopodinere out-
number very much the homosporous forms, but all of the former
may be reduced to a single genus, SelagineUa, which contains
nearly five hundred species, and, except for the presence of
heterospory, approaches closely the genus Lycopodiuin, to which
it is clearly not very distantly related. The great majority of
the species of SelagineUa belong to the tropics, and form a

XIII

LYCOPODINE^

511

characteristic feature of the forest vegetation of those regions.
A few belong to the more temperate parts of Europe and Amer-
ica, and a small number, e. g., S. rupestris, S. lepidophylla,
grow in dry situations.

The Ganietophyte

Hofmeister ( i ) included Selaginella among the other Pteri-
dophytes he studied, but he was unable to make out the earlier

Pjq_ 295. A, B. C, Three views of the young antheridium of Selaginella Krausstana,.

'x45o; D, an older stage of the same, X480; E, F, two views of an older an-
theridium of S. stolonifera, X480; G, spermatozoids of S. cuspidata, X1170; x,
vegetative prothallial cell; s, central cells (after Belajeff).

Stages of development of the prothallium. Later Millardet ( i )
and Pfeffer ( i ) made further investigations upon the same sub-
ject, and added much to Hofmeister's account, but were also
unable to determine the earliest phases of germination.

Belajeff (i) has since given an accurate account of the
germination of the microspores, and during the past ten years
the development of the macrospores and female gametophyte
has been very thoroughly investigated.

512 MOSSES AND FERNS chap.

The Microspores and Male Prothallium

The microspores of all species of Selaginella are small and
of the tetrahedral type. According to Belajeff (i) they may
show either a distinct perinium, or the latter is not clearly sepa-
rated from the exospore. The spores contain no chlorophyll,
but include much oil as well as solid granular contents. At the
time that the spores are shed each one has already divided into
two very unequal cells, a very small lenticular cell (Fig. 295, x)
and a much larger one which, as in Isoetes, becomes the single
antheridium.

The first wall in the antheridium divides it into two equal
cells, each of which then divides into two others, a basal and
an apical cell. The latter divides twice more, forming three
segments, so that the young antheridium at this stage consists
of eight cells arranged in two symmetrical groups. Of the
three segments formed in each apical cell, the first and some-
times the second form periclinal walls, so that a central cell
(or two cells) is formed in each half of the antheridium, not
unlike what obtains in Marsilia, and the young antheridium
consists now of two (or four) central cells and eight peripheral
ones. Belajeff states that the cell walls do not show the cellu-
lose reaction, and that they are later absorbed. Where there are
four primary central cells, these by further divisions produce
a single cell-complex, which, after the disintegration of the per-
ipheral cell walls, floats free in the cavity of the spore. Where
but two primary central cells are formed, each produces a sepa-
rate hemispherical cell mass. Belajeff does not state the num-
ber of sperm cells formed. The spermatozoids (Fig. 295, G)
are extremely small and closely resemble those of many Bryo-
phytes, as well as Lycopodiiim. Like these they are always
biciliate.

Miss Lyon (2) has given a very different account of the
male gametophyte in S. apiis. She states that in this species the
cytoplasm of the germinating spore contains large vacuoles sepa-
rated by bands of cytoplasm, which radiate from the central
^'generative" nucleus. The latter, with its envelope of proto-
plasm, then divides into "two cells," but how the membranes
about these free cells are formed is not stated. These two cells
give rise to the two masses of sperm-cells, and in the radiating
vacuoles are formed granular masses which, to judge from the

xm LYCOPODiNE^ 513

figures, are astonishingly cell-like in appearance. Until it can
be conclusively shown that these are not really cells, the state-
ment must be accepted with a certain amount of reservation.

A recent examination by the writer of some of the germi-
nating stages of the microspore of S. Kraussiana has shown
beyond question that in this species at least, Belajeff's statement
as to the formation of a peripheral layer of cells about the sperm
cells is correct. There was no trace of any vacuoles, the granu-
lar cytoplasm filling the spore completely and the walls sepa-
rating the peripheral cytoplasm from the central area were clear
and unmistakable. No attempt was made to verify the exact
succession of the division walls.

The Macrospore and Female ProthaUhim

The formation of the female prothallium begins while the
spore is still within the sporangium, and long before it has
reached its full size.

At an early period, shown first by Fitting (i), but later
verified by Miss Lyon (2) and Campbell (25), the protoplast
of the young macrospore separates from the inner spore mem-
brane (Fig. 296, A), and the outer spore-membrane increases
rapidly in size, so that a wide space separates the protoplasmic
vesicle from the inner spore-membrane. The minute globular
protoplast was mistaken by all the earlier observers for the pri-
mary nucleus of the macrospore, as it is very evident through
the transparent membrane at this time. The real nucleus is
very small and divides very soon, but the cytoplasmic layer re-
mains extremely thin. As the spore develops, the cytoplasmic
vesicle rapidly increases in diameter and finally comes again into
close contact with the endospore, or inner cellulose membrane
(Fig. 296, B). There is a middle lamella or mesospore (ni),
which is very conspicuous in the early stages, as it is also, ex-
cept at the apex of the spore, quite free from the thick outer coat,
the exospore. The space between the mesospore and exospore
is filled with a substance which stains faintly, and undoubtedly
contains material which is used by the growing membranes.

The nuclei (n) are small, and while the cytoplasmic layer
remains thin, are flattened. Later they increase rapidly in num-
ber, and with the thickening of the cytoplasmic layer, become
globular in form. At first they are pretty uniformly distrib-
uted, but later are more numerous at the apex of the spore; but
33

514

MOSSES AND FERNS

CHAP.

at no time in 5^. Kraussiana are they confined to this apical
region, as Miss Lyon states is the case in 6^. apus.

With the increase in the amount of protoplasm, the very-
large central vacuole hecomes reduced in size, and finally, but
this does not occur until after the germination of the spore, is

Fig. 296. — A, Young macrospore of Selaginella helvetica. The vesicular protoplast,
with the primary nucleus, is much smaller than the spore membranes, X400; B-E,
S. Kraussiana, sections of the older macrospore, showing the development of the
gametophyte; B, X about 200, the others more highly magnified; e, exospore; vi,
mesospore; n, nuclei; D, E, show the first cell-formation; D, vertical; E, horizontal
section of spore-apex. (A, after Fitting).

completely obliterated. In microtome sections it appears en-
tirely empty, but Heinsen ( i ) states that in tlie living state it
is occupied by great quantities of fatty oil. Whether this is
the case in 5. Kraussiana was not investigated.

XIII

LYCOPODINEJE

515

The protoplasmic layer is somewhat thicker at the apex, and
here begins the first cell-formation (Fig. 296, D, E). There
is but a single layer of nuclei at this point in vS'. Kraiissiana.
In S. apus there may be, according to Miss Lyon, six or seven
layers ; but none at all in the basal region of the spore.

Cell-division begins in 5^. Kraussiana by the simultaneous
appearance of delicate cell-walls between the nuclei at the apex
of the spore. These walls cut out cells (areoles), each, at least
in the central region, containing but a single nucleus. These

^:;^^^Em^^'^'''^'^'^^'^-^

!/
n.

■;;;.,i-Si..;. o>^

^i-•;•.o^V•.•.^

Fig. 297. — Selaginella Kraussiana. A, Longitudinal section of a nearly ripe macro-
spore, with the primary prothallium (Fr) complete, but still showing a large
vacuole in the centre of the spore, X65; B, similar section of a younger stage,
before the diaphragm has been differentiated, X400; n, free nuclei.

areoles are at first open upon their inner side, and the first cell-
formation resembles to a remarkable degree the typical endo-
sperm formation in the Spermatophytes. Fig. 296, E shows a
cross-section of the apex of the spore shortly after the first cell
walls are complete. The extremely regular hexagonal form of
the cells toward the centre of the prothallium is very noticeable.
At the margin, and below, the cells are larger, and often contain
several nuclei.

The cell-formation does not extend at this stage to the base
of the spore, as in Isoctcs, but is confined to the apex, where a
definite cellular body is formed. This is three-layered in the
middle, but at the margins but one cell in thickness. The lower
cells have the w^alls which are in contact with the spore-cavity

5i6 MOSSES AND FERNS chap.

much thickened at a later stage, and thus is formed the dia-
phragm which is so conspicuous in most species, and which led
Pfeffer to suppose that the first division in the young prothal-
lium proper from the lower part of the spore, in which later the
"secondary endosperm" is formed.

Scattered through the protoplasm of the spore-cavity below
the diaphragm are numerous nuclei. The protoplasmic layer
becomes rapidly thicker (Fig. 297, A), and finally completely
fills the cavity of the spore. The thickenings upon the outer
spore-coat are very evident even before the primary nucleus
divides, and they increase rapidly in size, as the spore develops.
A very casual examination suffices to show that the tapetal cells
of the sporangium here play a most important part, not only
in the development of the spore-coat, but also in the growth
of the prothallium. The rapid increase in the amount of pro-
toplasm in the spore during the growth of the prothallium, as
well as the growth of the spore itself, can only be accounted for
bv the activity of these cells, which are in close contact with
the spore, and show every evidence of being active cells, through
whose agency the materials are conveyed to the spore for its
further development.

The first archegonia begin to form shortly before the spores
are shed, and soon after, the exospore splits along the three ven-
tral ridges and exposes the central part of the prothallium.
This, like that of Isoetcs, is quite destitute of chlorophyll, and
is entirely dependent upon the food materials in the spore for
its further development. About this time also begins the cell-
formation in the part of the spore below the diaphragm (Fig.
298). This is simply a continuation of the same process by
which the apical tissue was developed, but the cells are larger
and more irregular.

The archegonia are produced in considerable numbers, and
apparently in no definite order. Their development corre-
sponds with that of Lycopodhim, but the neck is very short,
like that of the Marsiliacese, each row of neck cells having but
two cells. No basal cell is formed, and the central cell is sepa-
rated from the diaphragm only by a single layer of cells. The
neck canal cell (Fig. 298) is broad, like that of Isocfes, but the
nucleus does not, apparently, divide again. The egg (Fig. 298,
E) shows a distinct receptive spot, and the nucleus is clearly de-
iined. At this stage the diaphragm is very evident and much

XIII

LYCOPODINE^

517

thickened, so that the archegonial tissue of the prothaUium is
very sharply separated from the nutritive tissue below.

Sometime after germination begins, the vacuole completely
disappears, and sometimes a spongy-looking mass was seen
filling it before it finally disappeared. In the later stages, the
nuclei in the cytoplasm immediately below the diaphragm are
much more numerous and correspondingly smaller than those
in the much more coarsely granular cytoplasm of the basal
region. The finely granular protoplasm and numerous nuclei

Fig. 298. — Selaginella Kraussiana. A, Nearly median section of a fully-developed
female prothallium, showing the diaphragm (d), X 180. One of the archegonia
has been fertilised, and the suspensor (,sus) has penetrated through the diaphragm
into the tissue below it; B-E, development of the archegonium, X360; F, two-
celled embryo, belonging to the suspensbr shown in A, X360; G, end of a sus-
pensor with two-celled embryo {em), X360.

show the region where the cell-formation begins which results
in the secondary prothallial tissue.

Arnoldi (i) states that in ^. cuspidafa there is a single
large primary nucleus near the apex of the spore which is com-
pletely filled with cytoplasm. It looks very much, however,
as if he had mistaken the protoplasmic vesicle of the young

5i8

MOSSES AND FERNS

CHAP.

spore for the nucleus — if his statement is correct, 5'. cuspidata
differs very remarkably from other investigated species in the
development of the gametophyte.

Miss Lyon (2) found in both 5. apiis and 6^. rnpcstris a:
much greater development of the primary prothallial tissue than
is found in S. Kraussiana. To judge from her figures 54 and
55, there are two types of prothallium in S. apus, one in which
the base of the primary prothallium is sharply delimited, and
the other without any clear boundary between the primary and
secondary prothallial tissues.

The Embryo .^

The first division in tlie fertilised ovum is transverse, and
as in Lycopodiiun, the cell next the archegonium neck becomes

Cot.

G ^ F

Fig. 299. — Sclaginella Martensii. Development of the embryo (after Pfeffer). A, B,
D, E, Successive stages in longitudinal section, X340; C, apical view of a young
embryo with four-sided apical cell (x), X340; F, longitudinal section of the primary
root, X205; G, apex of the young sporophyte, showing the first dichotomy, X340.

the suspensor. This in Sclaginella is much more developed,
however, and grows at first more actively than the lower cell
from which the embryo proper arises. The upper part of the

XIII LYCOPODINE^ 519

suspensor enlarges somewhat, and forms a bulljons body, which
completely fills the venter of the archegonium. The suspensor
grows rapidly downward, penetrating the diaphragm and push-
ing the young embryo dow^n into the mass of food cells which
occupy the space below it. The suspensor is very irregular
in form, and undergoes several divisions (Fig. 298, G).

The first division in the embryo proper is almost vertical
(Fig. 298, F), and divides it into nearly equal parts. Beyond
this the early stages ot ihe embryo were not followed by the
writer, but to judge from the later stages, they correspond to
those of vS. Marfensii, which has been most carefully, studied
by Pfeffer ( i ) , the substance of whose work may be given as
follows. After the first wall is formed in the embryo, there
arises in one of the cells a second, somewhat cvu-ved one, which
strikes the primary wall about half-way up. llie cell thus cut
off, seen in longitudinal section, is triangular, and is the apical
cell of the stem (Fig. 299, A). The tw^o other cells (leaf-
segments) now undergo division by a vertical w^all, which
divides each into equal parts, and each of these pairs of cells
develops into a cotyledon. The apex of the young cotyledon
is occupied by a row of marginal cells in which divisions are
formed, like those in the apical cell of the stem, and in longi-
tudinal section the apex of the cotyledon seems to have a single
apical cell, much like the stem (Fig. 299, E). From the larger
of the leaf-segments, by a more active growth of the cells next
the suspensor, the foot is formed, and by its growth the stem
apex is pushed to one side, and its axis becomes almost at right
angles to that of the suspensor. Each cotyledon develops upon
its inner side, near the base, an appendage, the ligula (Fig.
300, /), which is a constant character of all the later leaves.

The primary root, as in Lycopodiiim, forms late, and no
trace of it can be seen until the other parts are evident. It
arises in the larger leaf-segmetit, close to the suspensor, and
therefore is separated from the cotyledon by the foot. The
root-cap arises from a superficial cell, which divides early by
both periclinal and anticlinal walls, and thus becomes two lay-
ered. From a cell immediately below is derived the single
apical cell to which the subsequent grow^th of the root is due.
The further divisions in the primary root were not followed.

The axes of the stem and root soon develop a strand of
procambium which is continuous in the two, but to judge from

520

MOSSES AND FERNS

CHAP.

Pfeffer's figures, the cotyledons do not develop their vascular
bundles until later. The early growth in length of the root
is mainly intercalary, as the divisions in the apical cell for some
time are not very rapid, and for a long time the root-cap con-
sists only of the two original layers.

With the growth of the embryo the cell-formation in the
lower part of the spore continues until it is filled with a contin-
uous large-celled tissue, the contents of whose cells are much
less granular than the undivided regions of the spore, and as
the embryo develops, the foot crowds more and more upon them

until it nearly fills the
spore cavity.

On comparing Pfeffer's
account of vS. Martensii
with my own observations
upon 6^. Kraiissiana, the
main differences consist
first in the smaller devel-
opment in the latter of
the primary prothallium,
i. e., the prothallial tissue
formed before the spores
are shed, the archegonia
being only separated from
the diaphragm by a single
layer of cells instead of by
three or four, as in S.
Martensii. L. apus, which
was also examined by the
wTiter, is intermediate in
this respect between the
tw^o. A second difference
is the later period at which the cell division in the lower part of
the prothallium is completed in 6". Kraussiana. In this species,
too, no rhizoids were seen, while Pfeffer observed them in 6'.
Martensii. Finally, in the latter the suspensor is much shorter
and straighter than in .9. Kraussiana. Miss Lyon (2) found
that in S. apus no suspensor w^as formed, but the development
of the embryo is not described.

In 6'. Martensii, almost as soon as the cotyledons are esta1>
lished, the two-sided apical cell of the stem is replaced by a

Fig. 300. — Longitudinal section of a fully-
developed prothallium of S. Kraussiana,
with an advanced embryo (em), X77', I,
ligula.

XIII

LYCOPODINEJE

S2I

four-sided one, from which are then produced two similar ones
by the formation of a median wall, and a true dichotomy of the
primary axis thus takes place at once, the two new branches
growing out at right angles to the cotyledon. While this may
also occur in 5^. Kraussiana (Fig. 301, D), it is not always the
case, and frequently the young plant remains unbranched until
it has reached a length of a centimetre or more, and has pro-
duced numerous leaves.

.R.

Cot.

•1

-r^ N^^V^jiV/'i///^., /''

Si^^ &p.

Fig. 301. — Selaginella Kraussiana. A, Macrospore with the prothalHum (pr), X50; ^>
young sporophyte still attached to the spore (sp), X8; cot, cotyledons; R, root; C,
upper part of an older stage, X6; D, a still older one showing the first di-
chotomy, X4.

The embryo of vS. spimilosa (Bruchmann (4)) has a short
and massive suspensor, and no foot is developed.

Miss Lyon (2) found that in both vS'. apiis and vS. rupestris,
fertilisation occurred while the spores were still within the spo-
rangium, and the sporangium attached to the strobilus. ''The
strobilus of 6". rupestris retains its physiological connection

522 MOSSES AND FERNS chap.

with the plant until tlie embryo has produced the cotyledons
and root." (/. c, p. 183).

In S. apus, the strobili are shed in the early autumn, whether
fertilisation has occurred or not. 6^. ntpcstris retains the stro-
bili through the winter, and fertilisation is effected in the spring.

From some partial observations made by the writer upon
spores of a species (probably /.. Bigclovii) from the dry
region of southern California, it looks very much as if, in this
species, the spores became completely dried up after the embryo
had already attained some size, and that the spores remained
in this condition through the dry season, the embryo resuming
its growth again in the autumn.

The Adult Sporophyte

The genus SclagincUa is a very large one, but there is some
difference of opinion as to the number of species. Hierony-
mus (i) enumerates 559 species, while Underwood (4) says
the genus contains ''about 335" species. The genus is usually
divided into two subgenera, Eiiselaginclla {Hoinocophyllum
of Hieronymus) and Stachygynandniin {HetcrophyUum,
Hieronymus). In tlie first are included those species in which
the leaves are all alike and arranged radially about the shoot,
which is generally more or less completely upright. S. riipes-
tris, S. sclagiiwidcs and vS. Bigclovii are examples. Tn Stachy-
gynandniin, which comprises the majority of the species, the
shoot is dorsi ventral, and often prostrate. The leaves are
four-ranked, those of the two dorsal rows being much smaller
than the others (Fig. 302). The first type suggests the species
of Lycopodinm of the type of L. annotinuni, the second that of
L. coinplanafuni or L. I'olubilc. In many species there is a
creeping stem from which upright branches grow, much as in
many species of Lycopodinm, but in others there is no clear dis-
tinction between these parts. The roots may arise directly
from the ordinary branches, but in many species, c. g., S.
Kranssiana, they are 1x)rne at the end of peculiar leafless
branches or rhizophores (Fig. 305, A). These, like the stem,
show an apparently regular dichotomous branching, which,
however, is really monopodial. The leaves, like those of Lyco-
podinm, are small, more or less lanceolate in outline, and with a
single median vein. In the homophyllous forms the sporo-

XIII

LYCOPODINEJE

523

phylls differ but little in appearance from the ordinary leaves,
but in the heterophyllous ones they are smaller than the other
leaves, and form a strobilus much like that of Lycopodiuni, but
usually less conspicuous.

The strobilus (Hieronymus (i), p. 653) may be either
erect or horizontal ; much more rarely it is pendent, and there
appears to be a certain relation between the arrangement of the
sporophylls and the position of the strobilus. Where it is up-
right the sporophylls are all alike, and disposed radially about
the axis. Where the strobilus is horizontal it is more or less
markedly dorsiventral in structure. In .S'. selaginoides and S.
deflcxa there is a more or less perfect spiral arrangement of the

Fig. 302. — A, Part of a fruiting plant of Selaginella Kraussiana, X3; sp, sporangial
strobilus; R, young rhizophore; B, longitudinal section of the strobilus, Xs; nia,
macrosporangium; mi, microsporangium.

sporophylls, but in all the other species they are four-ranked.
Usually in the latter case the sporophylls are alike, but there
may be the same difference in the dorsal and ventral leaves of
the dorsi-ventral strobili that is found in the sterile shoots of the
same species.

The basal leaves of the strobilus may be sterile, but usually
each sporophyll subtends a sporangium. In 5. Kraussiana,
and many other species of the same section of the genus, there
is but a single macrosporangium developed — the first formed

524

MOSSES AND FERNS

CHAP.

sporangium of the strobilus. This is much larger than the
microsporangia, and the sporophyll correspondingly large.
In other species, c. g., S. apiis, there may l)e several macrospo-
rangia. According to Hieronymus the position of the stro-
bilus conditions to some extent the development of macrospo-
rangia, which are either basal, or in that part of the strobilus

Fig. 303. — Selaginella Kraussiana. Horizontal section of the apex of the stem, X77', B,
the apical meristeni of the same, X450; s, the apex of the main axis; s', a young
lateral branch; B, B, young leaves; L, lig\ila of the leaf; C, D, longitudinal sec-
tions of the base of older leaves, X450; i, i. lacuna surrounding the vascular bun-
dles of the stem; t, one of the trabeculae.

nearest the ground. Thus in dorsiventral strobili they are de-
veloped on the ventral side; in pendent ones they may form at
the apex of tlie strobilus. Aliss Lyon made some interesting
observations upon the development of the sporangia in ^. apiis
and vS'. rupestris. In the latter species the strobili begin to de-

XIII

LYCOPODINE^

525

velop in the late summer and autumn, producing at this time
only macrosporangia. In the spring the growth of the stro-
bilus is resumed, and microsporangia are developed, the game-
tophytes produced from the macrospores of the previous year
being fertilised by spermatozoids developed from the micro-
spores developed in the spring. In 6^. apiis there was evidence
that the embryos formed in the autumn passed through the
winter within the macrospore, completing their development in
the spring.

The leaves arise much in the same way that the branches
do, but do not develop a single apical cell. The growth is

Fig. 304.— Cross-section of a fully-developed stem of S. Kraussiana, showing the two
vascular bundles suspended in the large central lacuna by means of the trabeculae
(0, X75; B, a single vascular bundle, X450; x, x, scalariform tracheids; s, s,
sieve-tubes.

much the same as in the first leaves of the embryo, and as in
these the early growth is due mainly to a row of marginal
initial cells from which segments are cut off alternately above
and below.

526 MOSSES AND FERNS chap.

If we examine a longitudinal section of the stem a short
distance below the apex (Fig. 303, A), we find a regular inter-
cellular space formed between the central stele (or steles),
which completely surrounds it, and becomes very conspic-
uous as the section is examined lower down. The formation
of this lacuna is similar to that in the capsule of the Bryales,
and, as there, the central mass of tissue is connected by
rows of cells with the outer tissue. These rows of cells (tra-
beculcT) are at first composed of but a single cell, but later by
tangential walls become slender filaments by which the vascu-
lar cylinders are suspended in the large lacuna which occupies
the centre of the stem (Fig. 304, t). According to Stras-
burger ((7), p. 457) both the trabeculae, which are usually re-
garded as endodermal, and the pericycle, are of cortical origin.

The fully-developed bundle in S. Kraussiana (Fig. 304, B)
shows a pericycle composed of a single layer of rather large
cells, within which lies the phloem, which completely surrounds
the xylem, as in the Ferns. The sieve-tubes in this species
form a single circle just inside the pericycle, but according to
Gibson ( (2), p. 176) are absent opposite the protoxylem. He
states that there is but a single group of protoxylem elements
here, but my own observations lead me to think that there are
two, as Russow affirms is the case. The origin of the proto-
xylem was not traced, but the appearance of the mature bundle
in the specimens examined (Fig. 304, B) points to this con-
clusion. The protoxylem is made up of small spiral and an-
nular tracheids, the metaxylem (secondary wood) of larger
scalariform elements, as in Lycopodiuin. The sieve-tul^es
have delicate walls and numerous, but poorly developed, sieve-
plates upon their lateral walls.

While in tlie main the anatomical characters are essentially
the same in all species examined, there are a number of differ-
ences to be noted (Gibson (i, 2)). Thus the stem may be
monostelic (S. Martoisii), bistelic (S. Kraussiana) , polystelic
(S. Iccvigata). In the former species the presence of silica in
the inner cortex has been demonstrated by Strasburger, and
Gibson has shown the same thing in other species. In this
species, too, besides the simple trabeculse found in ^. Kraus-
siana, others occur in which the outer cells undergo divisions in
more than one plane, and form a group of cells with which the
endodermal cell is articulated. In all species examined these

XIII

LYCOPODINE^

527

cells show more or less marked cutinisation. The number of
protoxylems in most species is two, but there may be accessory
ones.

The cortex is composed in most species of delicate paren-
chyma, with few or no intercellular spaces, and most of the
cells contain chlorophyll. In species like vS'. Icpidophylla, which
grow in dry localities, the cortical cells are sclerenchymatous,
with deeply-pitted walls and no lacuucC are present in the stem.
In the creeping stems, even in polystelic species, there is but a
single stele, which gradually passes over into the separate steles
of the upright stems.

Fig. 305. — A, Rhizophore, with roots of S. Kraussiana, XiVz; B, cross-section of the
vascular bundle of a root, X430; C, median longitudinal section of the leaf, X215.

The Leaf (Gibson (4, 5); Hieronymiis (/))

The leaves of Sclaginella are always of simple structure,
much like those of Lycopodium. Gibson (4, 5) has made an
exhaustive study of their structure, and the following account
is based upon his studies.

The leaf may be perfectly symmetrical in outline, or may
have one side more developed than the other. In some species
there are characteristic basal appendages, or auricles.

A section of the leaf (see also Fig. 303) in most species
shows a definite upper and lower epidermis, which may be com-

528 MOSSES AND FERNS

CHAr.

posed of similar cells, e. g., S. riipestris, or of cells of somewhat
different form on the two surfaces of the leaf, c. g., S. Mar-
tcnsii. Some of the epidermal cells may have the form of
sclerenchymatous fibres (S. subcrosa). The mesophyll is com-
posed of a loose network of cells, which may be all alike (S.
rupcstris) or less frequently, there is developed below the upper
epidermis, a palisade parenchyma (S. Lyallii). As a rule
stomata are formed only upon the lower epidermis, but there
are some exceptions.

The single median vascular bundle is concentric in struc-
ture, and the leaf-traces join the vascular cylinder of the stem,
as they do in Lycopodiiiui. The xylem consists of a single row
of annular tracheids, and three or four spiral ones. The
phloem is mainly composed of elongated parenchyma cells, but
one or two sieve-tubes can usually be demonstrated. Sur-
rounding the bundle is a pericycle consisting of a single layer
of cells, or in some cases more, but no definite endodermis is
present.

There is always developed at the base of the leaf the char-
acteristic ligula (Fig. 303, /). This develops at an early
period, and seems to be an organ for retaining moisture, as its
young cells develop abundant mucilage. In its fully developed
condition it shows a basal portion (glossopodium) composed
of large cells which are surrounded by a sort of sheath which is
continuous with the epidermis of the leaf. It varies in form in
different species. Thus in ^. Vogclii it is tongue-shaped; in
S. Martcnsii, fan-shaped; \nS. cuspidata, fringed (for further
details of its structure and development see Gibson (4)).

Simple hairs are of frequent occurrence in various parts of
the sporophyte.

The Chloroplasts

The chloroplasts of Sclaginclla are peculiar, on account of
their large size and small numbers. A careful study has been
made of these by Haberlandt (9), who found that in each of
the meristematic cells of the stem apex a single i)lastid was
present. This in the assimilative cells of the leaves either re-
mains undivided (S. Martcnsii), or it may become more or less
completely divided into two {S. Kranssiana) . In 5^. Willde-
nowii there may be as many as eight. In the cortical paren-

XIII

LYCOPODINE^

529

chyma of the stem the chloroplasts are apparently of the ordi-
nary form, but a careful examination shows that they are all
connected, and are directly referable to the divisions of the
primary plastid in the young cell. In all cases the nucleus is in
contact with the chloroplast or group of chloroplasts (Fig.
306). The character of the chloroplasts here has its nearest
analogy in Anthoceros, where occasionally a division of the
chloroplasts is met with, especially in the elongated cells of the
sporogonium.

UJ ^ I d R A R y ^

rcc

vCJ>.

''^©-^^

'<i?^X^^'

Fig. 306. — A, B, Cells of the mesophyll of Selaginella Martensii showing the single
chloroplast (c/) and the nucleus (n) ; C, chain of connected oval chloroplasts from
the inner cortex of the stem of 5". Kranssiana, X640 (after Haberlandt).

The Roots

The roots in 6'. Kranssiana are borne upon the special leaf-
less branches or rhizophores, which in structure are much like
the stem. Previous to the formation of the first roots upon the
rhizophore (Sadebeck (6) ), the apical cell is obliterated and re-
placed by a group of initial cells. The apical cells of the (usu-

530

MOSSES AND FERNS

CHAP.

ally two) roots formed arise secondarily, and quite independ-
ently of each other, from cells lying below the surface, and
covered with one or two layers of cells. These cells soon as-
sume a tetrahedral form, and become the apical cells of the pri-
mary roots. The branching of the roots, like that of the stem,
is really monopodial. although apparently a true dichotomy.
The vascular bundle of the root is monarch (Fig. 305, B),
and does not show a distinct endodermis. The phloem sur-
rounds the xylem completely, but apparently sieve-tubes are

Fig. 307. — Selaginclla Kraussiana. Development of the microsporangium, radial sec-
tions. A-C, X500; D, X235. The nuclei of the archesporial cells are shown.
L, The leaf subtending the sporangium.

not developed opposite the protoxylem. The elements of the
bundle are in structure like those of the stem-bundles.

The Sporangium {Gochcl (16) ; Bower (13))

The development of the sporangium is much like that of Ly-
CO podium, and has been studied by Goebel and Bower in 5.
spinosa, and by the latter in 6^. Martensii also. In 5^. Kraus-
siana (Fig. 307, A) a radial section of the young sporangium
shows a very regular arrangement of the cells, with a single
central archesporial cell (the nucleated cell of the figure).
This evidently has arisen from a hypodermal cell of the central
row, and from it is already cut off by a periclinal, an outer cell.

XIII

LYCOPODINEJE

531

The whole closely resembles Goebel's figures of 5'. spinosa. A
comparison with older stages indicates that from this central
cell alone the sporogenous cells are produced, as in Lycopodium
selago. The outer row of cells does not divide by periclinal
walls, and from the first forms an extremely distinct layer.
The first cell cut off from the archesporium divides again by a
periclinal wall (Fig. 307, B), and the inner cell forms prob-
ably the first tapetal cell, although in some cases it looks as if
this cell took part in the formation of spores. The arche-

FiG. 2o8.—Selaginella Kraussiana. A, Radial section of a nearly ripe microsporangium,
Xioo; /, ligula of the subtending leaf; t, tapetum; B, section of young macro-
sporangium (about half grown), showing the papillate tapetal cells (0, X6oo; C,
section of the wall of a young macrospore from the same sporangium, X6oo.

sporium undergoes repeated divisions to form the sporogenous
tissue, and finally the layer of cells between this and the pri-
mary wall divides by periclinal walls to form the tapetum,
which here remains intact until the spores are nearly or quite
mature. The formation of the stalk is the same as in Lyco-
podium.

It is quite possible that the apparently single archesporial
cell of 5^. Kraussiana may be one of a transverse row of arche-
sporial cells, like those of 5^. Martensii.

532 MOSSES AND FERNS chap.

Miss Lyon (2) thinks that in both 5^. a pus and vS'. riipcstris
the whole sporangium may be traced back to a single super-
ficial cell, which she calls the archesporium.

Bower (15) considers it probable that in vS. spinosa and S.
Martensii the sporogenous tissue cannot be traced back always
to a single cell (in radial section), and has also shown that
when tangential sections are examined, as in Lycopodiuni, the
archesporium always is a row of cells.

In all species of Sclaguiclla yet examined, the sporangium
is not of foliar origin, but originates from the axis above the
insertion of the leaf by which it is subtended.

As in Lycopodiuni the tapetal cells do not become disorgan-
ised, but remain intact as the inner layer of cells of the three-
layered sporangium wall. They form an epithelium-like layer
of papillate cells, distinguished by their dense granular con-
tents, and it is evident that they are actively concerned in the
elaboration of nutriment for the growth of the young spores
(Fig. 308).

As in the other heterosporous Pteridophytes, the two sorts
of sporangia are alike in their earlier stages, and this in Scla-
ginclla continues up to the time of the final division of the spore
mother cells. In the microsporangium, all of the sporogenous
cells undergo the usual tetrad division ; but in the macrospo-
rangium only a single one normally divides. Occasionally
one of the divisions is suppressed so that but two macrospores
result. In the microsporangium all of the spores mature, and
the spores remain small. The single tetrad of macrospores in-
creases enormously in bulk, and finally completely fills the mac-
rosporangium, which is itself much larger than the microspo-
rangia, and by the crowding of the enclosed spore-tetrad, as-
sumes a four-lobed form. The cells of the wall remain green
and fresh up to the time that the macrospores are ripe, and
sections show that the tapetal cells are in close contact with the
wall of the spores. The episporic ridges are very evident be-
fore the spore has reached half its final diameter, and sections
of the spore wall at this time (Fig. 308, C) show the spine-like
section of the surface ridges. The wall rapidly increases in
thickness as the spores grow, and this increase is evidently due
almost entirely to the activity of the tapetal cells, as the spore
at this stage contains very little protoplasm. The first nuclear
division in the macrospore takes place when the spore is about

XIII

LYCOPODINE^ 533

half-grown, and by the time it has reached its full size the cell
divisions in the apical region are complete and the archegonia
have begun to form. (For details of the spore-development
in Selaginella see Fitting ( i ) ) .

The ripe sporangium opens by a vertical cleft, as in Lyco-
podiiim. Goebel (22) has recently descril^ed in detail the
mechanism involved in the dehiscence of the sporangium.

The Affinities of the Lycopodineco

Among the living Lycopodineae there are two well-marked
series, one including the Lycopodiacese and Selaginellacese, the
other the Psilotaceae. In the first, beginning with Phylloglos-
sum, the series is continued through the different forms of
Lycopodiiim to the Selaginellacese. The relation of the Psilo-
taceae to this series is doubtful, and must remain so until the
sexual generation of the former is known. The probable
saprophytic or parasitic life of these plants makes it impossible
to determine just how far their simple structure is a primitive
character rather than a case of degradation.

Of the first series, it seems probable that of the forms whose
life history is known, the type of L. cernmim represents the
most primitive form of the gametophyte. It is reasonable to
suppose that in all these forms the prothallium was green, and
that the saprophytic prothallia, like those of L. phlegmaria and
L. annotimim, are of secondary origin. The prothallium, of
the type of L. cernuum, may be directly connected with the
Bryophytes and resembles them also in the small biciliate
spermatozoids, in which latter respect all the Lycopodinese yet
examined agree. This latter point is perhaps the strongest
reason for assuming that the Lycopods represent a distinct line
of development, derived directly from the Bryophytes, and not
immediately related to either of the other series of Pterido-
phytes. The character of the archegonium, as well as the long
dependence of the embryo upon the prothallium and the late
appearance of the primary root, point to the genus Lycopodiiim
as a very primitive type, even more closely related to the Bryo-
phytes than are the eusporangiate Ferns. Phylloglossnm, at
least so far as the sporophyte is concerned, is the simplest liv-
ing Pteridophyte.

The close relation of Selaginella to Lycopodinm is suf-

534 MOSSES AND FERNS chap.

ficiently obvious. It is, however, interesting to note that Sel-
agiuella seems to have retained certain characters that are ap-
parently primitive. These are the presence of a definite apical
cell in the stem and root of most species, and the peculiar chlo-
roplasts, which are especially interesting as a possible survival
of the type found in so many Confervacece, e. g., Colcochcote,
from which it is quite likely that the whole archegoniate series
has descended. This form of chloroplast occurs elsewhere
among the Archegoniata^ only in the Anthocerotes.

In the characters of the sporangium and the early develop-
ment of the prothallium, SclagincUa undoubtedly shows the
closest affinity to the Spermatophytes, especially the Gymno-
sperms, of any Pteridophyte. The strobiloid arrangement of
the sporophylls and the position of the sporangia are directly
comparable to the strobilus of the Coniferse. The wall of the
sporangium is here not only morphologically, but physiologic-
ally comparable to the nucellus of the ovule, and the macro-
spore grows, not at the expense of the disorganised spo-
rogenous cells and tapetum alone, but is nourished directly
from the sporophyte through the agency of the cells of the
sporangium stalk and wall, until the development of the en-
closed prothallium is far advanced. The latter, both in its
development while still within the sporangium, as well as in
all the details of its formation, shows a close resemblance to
the corresponding stages in certain Conifers. The formation
of a ''primary'' and ''secondary" prothallium is, as we have
seen, only apparent, and the diaphragm in the prothallium of
Selaginella is not a true cell wall, marking a primary division
of the spore contents, but only a secondary thickening of the
lower walls of certain cells, indicating a temporary cessation in
the process of cell-formation. It is by no means improbable
that this cell-formation may sometimes go on uninterruptedly,
in which case no diaphragm would be formed, and, as in Isoetes,
there would be no distinct line of demarcation between the
archegonial tissue at the apex and the large-celled nutritive
tissue below.

The presence of a suspensor in all investigated Lycopodinese
is a character which distinguishes them at once from the other
Pteridophytes, and has its closest analogy again among the
Conifers.

The possibility that the Psilotacece may not be directly re-

XIII LYCOPODINE^ 535

lated to the other Lycopodine^e has been referred to. As noth-
ing is known at present of the gametophyte and embryo, this
point must, for the present, remain open.

Fossil Lycopodinece

Many fossil remains of plants undoubtedly belonging to the
LycopodinecX are met with, especially in the Coal-measures,
where the Lepidodendreae were especially well developed. Of
homosporous forms, it seems pretty certain that the fossils
described under the name Lycopodites are related to the living
genus Lycopodiiim, and certain fossils from the Coal-measures
have even been referred to the latter genus, some of these being
homophyllous, others heterophyllous. Solms-Laubach thinks
it somewhat doubtful whether the plants described by various
writers, and belonging to older formations, really are Lyco-

podinese.

In regard to the Psilotacese he says : "The statements re-
specting fossil remains of the family Psilotacece are few and un-
certain, nor is this surprising in such simple and slightly differ-
entiated forms. If Psilotites . . . does really belong to this
group, a point which I am unable to determine from the figures,
we should be able to follow the type as far down as the period
of the Coal-measures."

A discussion of some of the numerous characteristic fossil
Lycopods will be left for a special chapter.

CHAPTER XIV

ISOETACE^E

The genus Isoctcs, the sole representative of the family Isoe-
taceae, differs so much from the other Pteridophytes that there
has been a good deal of difference of opinion as to where it
should be placed. Isoetes is most commonly associated with
Selaginella, and there are undoubtedly marked resemblances be-
tween the two genera in certain anatomical details, and in the
development of the spores and gametophyte. On the other
hand, the embryo and the spermatozoids are much more like
those of the lower Ferns, with which they have sometimes been
associated. Whether the Isoetacere are assigned to the Fili-
cineae or Lycopodineae, they are sufficiently distinct to warrant
the establishment of a separate order, Isoetales.

According to Sadebeck (8), there are 62 species of Isoetes.
Of these sixteen are found in the United States.

Isoetes has been the subject of repeated investigation, Hof-
meister ( i ) being the first to study its development in detail.
The sporophyte is in most species either aquatic or amphibious,
but a few species are terrestrial. They are very much alike in
appearance, having a very short stem whose upper part is com-
pletely covered with the overlapping broad bases of the leaves,
which themselves are long and rush-like, so that the plant in
general appearance might be readily taken for an aquatic
Monocotvledon. The roots are numerous and dichotomouslv
branched. The stem grows slowly in diameter, and the older
ones show two or three vertical furrows that unite below, and
as the stem continues to grow these furrows deepen, so that the
old stem is strongly two or three lobed. In the furrows the
roots are formed in acropetal succession. The leaves are closely

set and expanded at the base (Fig. 309) into a broad sheath,

536

xrv

I SORT AC EM

537

with membranaceous edges. Just above the base of each per-
fectly-developed leaf is a single very large sporangium, sunk
more or less completely in a cavity (fovea), which in most

Fig. 309.— a, Plant of Isoetes Bolanderi, X 1 ; B, base of a leaf with macrosporan-

gium, X4; ^, ligula; v, velum.

Species is covered wholly or in part by a membranaceous indusi-
um (velum), and above the fovea is a scale-like outgrowth of

538

MOSSES AND FERNS

CHAP.

the leaf, the Hgula. The spores are of two kinds, borne in sepa-
rate sporangia. The outer leaves of each cycle produce micro-
spores, the inner ones macrospores, many times larger than the
former. The innermost leaves, which are not usually perfectly
developed, are sterile, and separate one year's growth from the
next. In some of the land forms, c. g., I. hystrix, these sterile
leaves are very much reduced, and form spine-like structures.

The Gametophyte

The germination of the microspores was studied by Hof-
meister (i), and later by Millardet (i) and Belajeff (i), the

Fig. 310. — A-G, Isoetcs echinospora, var. Braunii. Development of the antheridium,
X about 1000. H, Spermatozoid of /. Malinverniana (li, after Belajeff).

later writer differing in some essential particulars from the
earlier observers. The two former studied /. lacustris, the lat-
ter, /. sctacea and I. Malinverniana, which do not seem to differ,
however, from I. cchinospora, which was investigated by
the writer. The microspores of all the species are bilateral, and
are small l^ean-shaped cells with thick but in most species nearly
colourless walls. The epispore sometimes has spines «upon it,

XIV I SORT ACE JE 539

but in /. echinospora var. Braiinii the surface of the spore is
nearly smooth. In this species the spores begin to ripen in the
early autumn, and continue to do so as long as the conditions
permit of growth. The spores are set free by the decay of the
sporangium wall, which probably in nature is not completely
the case until winter or early spring, which seems to be the
natural time for germination. If they are set free artificially,
however, they will germinate promptly, especially if this is done
late in the autumn or during the winter. Thus spores sown in
December produced free spermatozoids in two weeks. The
spores do not all germinate with equal promptness, and all
stages of development may be met with in the same lot. The
ripe spore has no chlorophyll, but contains besides the nucleus,
albuminous granules, small starch grains, and oil.

The first division wall cuts off a small cell from one end,
which undergoes no further development, and represents the
vegetative part of the prothallium, which is here absolutely
rudimentary. The rest of the spore forms at once the single
antheridium. In the latter two, walls are formed so inclined to
each other as to include two upper cells and one loXver one (Fig.
310, C). This latter next divides into two by a vertical longi-
tudinal wall, and each of the resulting cells is further divided
by a periclinal wall, so that the antheridium consists of four per-
ipheral cells and two central ones. The latter finally divide
again, by vertical walls, making four central cells, which become
at once the sperm cells. According to Belajeff the walls of the
peripheral cells become dissolved finally, so that the sperm cells
float free within the spore cavity. Each sperm cell forms a
single coiled spermatozoid, which is more slender than that of
Marattia, but like it is multiciliate.

In microtome sections of the germinating spores of /. echino-
spora, the walls of the peripheral cells were evident after the
spermatozoids were completely -formed, and there seems some
doubt whether they are absorbed at all. Occasionally (Fig.
310, D) the sperm-cells were divided into two separate groups
as in Marsilia.

The macrospores are very many times larger than the micro-
spores, and are of the tetrahedral type instead of bilateral.
They are nearly globular in form and show plainly the three
converging ridges on the ventral surface. If the fresh spore
is crushed in water, its contents appear milky, and microscopic

540

MOSSES AND FERNS

CHAP.

examination reveals numerous oil-drops and some starch-
granules, mingled with roundish bodies of albuminous nature.
The latter absorb water and swell up so that they look like free

cells.

The wall of the spore is very thick. The perinium is thick

•/H*'

■••^:;- vh^:: ;.•:•••:• -V

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1^ ^

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^ O

u o

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u
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'S
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60

o u
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(I4

and transparent in appearance, and in the species under con-
sideration provided with short recurved spinules. The interior,
in microtome sections, is filled with coarsely granular cytoplasm,
which often appears spongy, owing no doubt to the dissolving

XIV ISOETACE^ 541

out of the oil. Scattered through the cytoplasm are round
starch granules with a central hilum. The large nucleus lies
in the basal part of the spore. It is broadly oval in outline,
and the cytoplasm immediately about it is nearly free from large
granules. Before germination begins there are few chro-
mosomes, and the nucleolus does not stain readily.

In /. lacustris (Farmer (2)) the primary nucleus is at the
apex of the spore, and this is also the case in /. Malinverniana
(Arnoldi (i)).

After the spores have lain a few days in water, the nucleus
increases in size, and then the nucleolus stains very intensely
and the chromosomes become more conspicuous. The nucleus
divides while still in its original position, and undergoes division
in the usual way. A very evident cell plate is formed in the
equator of the nuclear figure (Fig. 311, A), but no cell wall is
found, and the result of the division is two large free nuclei.
The next youngest stage observed (Fig. 311, B) had four free
nuclei, which now had moved to the ventral side of the spore.
These are very much smaller than the primary one, but are
relatively richer in chromatin. They continue to divide until
there are from about thirty to fifty free nuclei, but as yet no
trace of cell division can be seen. Most of the nuclei lie in
the ventral part of the spore, close to the outer wall, but an
occasional one may be detected elsewhere.

Cell division begins at the apex (ventral part) of the spore.
At this time the cytoplasm stains more deeply than before,
and sometimes extremely delicate threads may be detected,
radiating from the nuclei and connecting adjacent ones (Fig.
311, C). The first traces of the division walls appear simul-
taneously between the nuclei in the form of cell plates composed
of minute granules, probably of cellulose, which quickly coalesce
and form a continuous membrane. In this way the upper part
of the spore becomes transformed into a solid tissue (Fig. 312).

The formation of the cell walls closely resembles that in
Selaginella. The primary cells, or areoles, are open in their
inner faces, and it is not until the second nuclear division takes
place that the inner cell wall is developed. (Arnoldi ( i ), Figs.

5,6).

The cell formation proceeds quickly toward the base of the
spore, following the spore wall, so that for a time the central
space remains undivided. The whole process recalls most

542

MOSSES AND FERNS

CHAP.

vividly the endosperm formation of most Angiosperms. On
account of the extremely thin walls and dense contents of the

Fig. 31:2. — Isoetes ccJxinospora var. Braunii. A, Longitudinal section through tlie apex
of the female prothalliuni, showing the first cell formation, X300; B, similar sec-
tion of a prothallium with the divisions completed and the first archegonium (or)
already opened.

young prothallial cells it is not easy to determine exactly when
the whole spore cavity becomes filled up with cellular tissue.

XIV ISOETACE^ 543

Because of the greater number of free nuclei in the upper part
of the spore, and their consequent close proximity, the cells
are smaller than those in the central and basal parts of the pro-
thallium. Sometimes the transition from this small-celled tissue
to the large-celled tissue of the basal part is quite abrupt and
the more noticeable as the upper cells are more transparent ; but
there was nothing to indicate that this was in any way con-
nected with the early divisions of the primary nucleus, and more
often no such sudden transition was seen.

Hofmeister's account of the coalescence of previously sepa-
rate cells to form the prothallium was obviously based upon
incorrect observation, and is not borne out by a study of sections
of the germinating spore.

The first archegonium is very early evident, generally be-
fore the cell division is complete in the lower part of the spore.
It occupies the apex of the prothallium, and the mother cell is
distinguished by its large size and dense granular contents.
It is simply one of the first-formed cells that soon ceases to
divide, and as its neighbours divide rapidly the contrast between
them becomes very marked. Whether seen from above or in
longitudinal section, it generally is triangular, or nearly so. In
the structure of the mature archegonium, Ophioglossnin shows
strong points of resemblance, as do the Marattiacese, but the
egg cell is much larger in Isoetes.

The development of the archegonium corresponds almost
exactly with that of Maraffia, but the basal cell is always want-
ing, and the first transverse wall separates the central cell from
the cover cell. The first division in the inner cell is parallel
with the base of the cover cell, and divides it into the primary
canal cell and central cell. The contents of the three cells of
which the archegonium is now composed are similar, and the
nuclei large and distinct. The cover cell next divides into four
by transverse walls (Fig. 311, E), and from these, as in Marat-
tia, the four rows of cells of the neck are formed. The number
in each row is usually four in the mature archegonium. The
ventral canal cell, which like that of Marattia extends the whole
breadth of the central cell, is separated almost simultaneously
with the appearance of the first transverse divisions in the neck
cells. The neck canal cell has at first a single nucleus, which
later divides, but there is no division wall formed. Although
the number of cells in each row of the neck is usually greater

544

MOSSES AND FERNS

CHAP.

than in Marattia, the neck canal cell is shorter and extends but
little between the neck cells (Fig. 313, B).

The egg is very large, round or oval in form, and the
nucleus contains a large nucleolus that stains very intensely,
but otherwise shows little chromatin. The receptive spot is of
unusual size, and occupies about one-third of the tgg. It is

Fig. 313. — Tsoctes cchinospora var. Braunii. Development of the archegonium, Xsooj
o, the egg; v, ventral canal cell; h, neck canal cell; D, shows a two-celled embryo
within the archegonium.

almost hyaline, showing, however, a faint reticulate arrange-
ment of fine granules ; the lower portion of the egg is filled with
granules that stain strongly.

In /. laciistris, according to Hofmeister, only one arche-
gonium is formed at first, and if this is fertilised, no others are
produced; but in /. cchinospora, even before the first arche-
gonium is complete, two others begin to develop and reach ma-
turity shortly after the first, w^hether the latter is fertilised or

XIV

ISOETACE^ 545

not. In case all of these primary archegonia prove abortive, a
small number, apparently not more than five or six, may be
formed subsequently ; but so far as my observations go, the pro-
duction of archegonia is limited, as is the growth of the pro-
thallium itself.^

The development of the prothallium goes on without any
increase in size, until the first archegonium is nearly complete,
about wdiich time the spore opens along the line of the three
ventral ridges, and the upper part of the enclosed prothallium
is exposed, but projects but little beyond the opening. In case
all the archegonia prove abortive, the prothallium continues
to grow until the reserve food material is used up, but then dies,
as no chlorophyll is developed in its cells, and only in very rare
instances are rhizoids formed.

Miss Lyon (3) figures a longitudinal division of the neck
canal cell in /. lacnstris, and Arnoldi (i) states that a similar
division may occur in /. Malinverniana.

The Embryo

Besides the earlier account of Hofmelster, Kienitz-Gerloff
(6) and Farmer (2) have made some investigations upon the
embryogeny of /. lacustris, which correspond closely, so far as
they go, with my own on /. ecJiinospora.

The youngest embryos seen by me had the first division w^all
complete (Fig. 313, D). This is transverse, but more or less
inclined to the axis of the archegonium. The nuclei of the two
cells are large and contain several chromatin masses. The sec-
ond division in the epibasal and hypobasal cells does not ahvays
occur simultaneously, the lower half sometimes dividing before
the upper one, and at times the second walls are at right angles
instead of in the same plane. Of the quadrants thus formed,
the two lower form the foot, and the two upper ones the cotyle-
don and primary root. The stem apex arises secondarily at a
later period, and probably belongs to the same quadrant as the
root ; but as it does not project at all, and is not certainly recog-
nisable until after the boundaries between the quadrants are no
longer evident, this cannot be positively asserted.

Sometimes the quadrants divide into nearly equal octants,

*In old prothallia of /. lacustris according to Kienitz-Gerloff (6), there
may be 20 to 30 archegonia.

546

MOSSES AND FERNS

CHAP.

but in several young embryos examined, no definite octant walls
were present, at least in the upi)er octants, but whether this
is a common occurrence would be difficult to say. The next
divisions in the embryo resemble those in Marattia, and as in the
latter it may be said that the young members of the embryo
grow for a short time from an apical cell, inasmuch as the tetra-
hedral octants at first have segments cut off parallel with the
basal, quadrant, and octant walls, leaving an outer cell (Fig.
314, A) that still retains its original form; but very soon peri-

FiG. 314.— A, An embryo of I. echinospora var. Braunii, with unusually regular
divisions, X450; B, a much older one, still enclosed within the prothallium, X150;
ar, archegonia.

clinal walls arise in this cell in each quadrant, and it is no longer
recognisable as an apical cell, and from this time the apex of the
young memljer grows from a group of initial cells.

Up to this time the embryo has increased l)ut little in size,
and retains the globular or oval form of the Qgg. It now
elongates in the direction of the basal wall, and soon after, the
cotyledon and primary root l)ecome differentiated. The axis
of the former coincides with the plane of the basal wall, and it

XIV

ISOETACE^

547

approaches more or less the vertical as the latter is more or less
inclined. Occasionally the basal wall is so nearly vertical that
the cotyledon grows upright and penetrates the neck of the
archegonium at right angles to its ordinary position. At the
base of the leaf at this stage a single cell, larger than its neigh-
bours, may often be seen (Fig. 315, A, /). This is the mother
cell of the ligule, found in all the leaves. This cell projects,

Pig. 315. — Development of the embryo in I. ecUnospora var. Braunii. A, Median longi-
tudinal section of a young embryo; B, four horizontal sections of a younger one;
C, two vertical transverse sections of an older embryo; /, the ligula, X300.

and as the leaf growls divides regularly by walls in a manner
compared by Hofmeister to the divisions in the gemmae of
Marchantia. It finally forms a scale-like appendage about
twelve cells in length by as many in breadth.

Almost coincident with the first appearance of the ligule
a depression is evident, which separates the bases of the cotyle-
don and root. The base of the latter, which now begins also to

54«

MOSSES AND FERNS

CHAP.

grow in length, projects in the form of a semi-circular ridge that
grows rapidly and forms a sheath about the ligule and the base
of the cotyledon (Fig. 317, r). The growth of this sheath is
marginal, and continues until a deep cleft is formed. A num-
ber of cells at the bottom of the latter between the sheath and the
leaf base constitute the stem apex. As they differ in appear-
ance in no wise from the neighbouring cells, it is quite impossible

Fig. 316. — Three successive horizontal sections of a somewhat advanced embryo of
/, echinospora var. Braunii, X260; R, root; cot, cotyledon; st, stem; /, ligula.

to say just how many of them properly belong to the stem. So
far as can be judged, the origin of the growing point of the
stem is strictly secondary, and almost exactly like that of many
Monocotyledons.^

Longitudinal sections of the embryo, when root and leaf are

^ See Hanstein's figures of Alisvia, for example, in Goebel's Outlines,
Fig. 232.

XIV ISOETACE^ 549

first clearly recognisable, show that the foot is not clearly de-
fined, as the basal wall early becomes indistinguishable from the
displacement due to rapid cell division in the axis of the embryo.
It projects but little, and the cells are not noticeably larger than
those of the cotyledon and root.

As the cotyledon lengthens it becomes somewhat flattened,
and in the later stages its increase in length is due entirely to
basal growth. Even in very young embryos a distinct epi-
dermis is evident in the leaf, and about the time that the ligule
is formed the first trace of the vascular tissue appears. This
consists of a bundle of narrow procambium cells, which lie so
near the centre of the embryo that it is impossible to assign it

Fig. 317.— Median longitudinal section of an embryo~of the same species shortly before
the cotyledon breaks through the prothallium; lettering as in the preceding, X300.

certainly to either root or leaf; indeed it sometimes seems to
belong to one quadrant, sometimes to the other. From it the
development of the axial bundles of cotyledon and root pro-
ceeds, and by it they are directly united. The section of the
central cylinder of the leaf is somewhat elliptical, and it does not
extend entirely to the end. Its limits are clearly defined from
the periblem, in which the divisions are mainly transverse and
the cells arranged in regular rows.

The primary xylem consists of small spiral and annular
tracheids at the base of the leaf, and from these the formation
of similar ones proceeds tow^ards the tip. Their number is
small, even in the full-grown leaf, and they are the only differ-

550

MOSSES AND FERNS

CHAP.

entiated elements, the rest of the bundle showing only elongated
parenchyma, much like the original procaml)ium cells.

The axis of growth of the primary root usually coincides
with that of the cotyledon, but this is not always the case. In

Fig. 318. — A, Median section of a young sporophyte with the second leaf L- already
formed; r^, second root; st, stem-apex, X150; B, cross-section near the base of the
cotyledon, showing the intercellular spaces i and the second leaf U surrounded by
the sheath v at the base of the cotyledon; /, the ligule of the cotyledon, X300.

the very young root (Fig. 317, R) the end is covered with a
layer of cells continuous with the epidermis of the rest of the
embryo. Beneath are two layers of cells concentric with the

XIV ISOETACE^ 551

epidermis. From the inner one arises the initial cell (or cells?)
of the plerome, which soon becomes well defined and connected
with the primary strand of procambium in the axis of the em-
bryo. It is cjuite possible that here, as in the older roots, a
single initial cell is present in the plerome, but this is not cer-
tain. The layer of cells immediately below the primary epi-
dermis is the initial meristem for all the tissues of the root
except the plerome. The primary epidermis later divides into
two concentric layers which take no further part in the growth
of the root except as they join the outer layers of the root-cap.

From the layer above the plerome initial, additions are made
at regular intervals to the root-cap, and these layers remain one
cell thick, so that the stratification is very marked. At the
apex of the root there is no separation of dermatogen and peri-
blem, which are first differentiated back of the apex. The pri-
mary xylem consists of very delicate spiral tracheids formed at
the base of the root at the same time that the first ones appear
in the leaf.

The foot increases much in size as the leaf and root develop,
and its superficial cells become much enlarged and encroach
upon the large cells of the prothallium, whose contents are
gradually absorbed by it.

The cotyledon is at first composed of compact tissue, which
during its rapid elongation separates in places, and forms a sys-
tem of large intercellular spaces. There are two rows of very
large ones, forming two broad air-chambers extending the
whole length of the leaf, but these are interrupted at intervals
by imperfect partitions composed of single layers of cells. In
the root there are similar lacunae, but they are smaller and less
regularly arranged.

The growing embryo is for a long time covered by the pro-
thallial tissue, wdiich in the upper part continues to grow with
it; but finally cotyledon and root break through, the former
growing upward, the root bending down and anchoring the
young sporophyte in the mud. Owing to the large air-spaces
the cotyledon is lighter than the water, and always stands ver-
tically, whether the original position was vertical or horizontal.
In the latter case the plant appears to be attached laterally to the
prothallium, and the stem apex, which when first formed stands
almost vertically, now assumes the horizontal position which
it has in the older sporophyte.

552

MOSSES AND FERNS

CHAP.

About the time that the young sporophyte breaks through
the prothalhum, the second leaf begins to develop. The grow-
ing point (Fig. 318, st) now lies in the groove between the
base of the root and the cotyledon, and its nearly flat surface
is at right angles to the axis of the latter. The second leaf
(L^) arises as a slight elevation on the side of the stem directly
opposite the cotyledon. From the first it is multicellular, and
its growth is entirely like that of the cotyledon, which it other-
wise resembles in all respects. Almost as soon as the leaf is
evident at all, a strand of procambium cells is formed running
from the junction of the cotyledon and first root, and is con-
tinued into the second leaf as its plerome.

The second root develops
from the base of the second leaf
in the immediate vicinity of the
' common fibrovascular bundle,
and is formed about the time
that the leaf begins to elongate.
A group of cells here begins to
multiply actively, and very soon
shows a division into the initials
of the tissue systems of the
young root. From this time
the growth proceeds as in the
primary root, and it finally
breaks through the overlying
tissues.

The stem has no vascular
bundle apart from the common
bundle formed from the coales-
cence of the bases of the bundles from the leaves and roots. In
all the later-formed leaves and roots there is but a single axial
bundle. In the leaves this is decidedly collateral in form with
the poorly-developed xylem upon the inner (upper) side. Ex-
cept for their larger size, and their having usually four instead
of two air-channels, the later leaves resemble in all respects those
first formed.

The development of the young plant was not followed be-
yond the appearance of the third leaf, but it probably in its later
history corresponds to /. iacusfris. In the latter, according to
Hofmeister ((i), p. 354), the opposite arrangement of the

Fig. 319. — Longitudinal section of the
second root, X525; PI, pkrome.

XIV

ISOETACEJE

553

leaves continues up to about the eighth, when the i divergence
is replaced successively by ^, |, |, ^%, and /t, which is the con-
dition in the fully-developed sporophyte.

The Adult Sporophyte {Sadebeck (p))

The structure of the mature sporophyte has been the sub-
ject of repeated investigations, among the most recent being

Fig. 320.— a, B, Isoetes echinospora. A, Section of fully developed leaf, X15; B,
vascular bundle of the leaf, X about 200; C, part of a transverse section of the
stem of /, lacustris; sp, starch-bearing cortical cells; m, meristematic zone; h,
tracheids; hd, tissue of the central region (C after Potonie).

those of Farmer (2) and Scott (2), who made a most careful
examination of the vegetative organs in 7. lacustris and 7. hys-
trix. The thick, very short stem has a central vascular bundle;,
which as in the young plant is made up of the united leaf-traces,,
and there is no strictly cauline portion, as Hegelmaier (i) and

554 MOSSES AND FERNS chap,

Bruchmann (i) assert. Scott (2), however, states that in /.
hystrix, there is a short, cauhne stele distinct from the leaf
traces.

This central cylinder is composed of very short tracheids,
with spiral and reticulate markings, mixed with similarly-
shaped cells with thin walls. Surrounding this xylem cylinder
is a layer of cells, which Farmer calls the ^'prismatic layer."
This, according to Russow ((i), p. 139), is continuous with
the phloem of the leaf-traces, and he regards it as the phloem of
the stem hundle. Outside of this prismatic layer is a zone of
meristematic cells, which form the "camhium." The cells of
this zone are like those of the camhium of BoytrycJiium or of
the Spermatophytes, and like these new cells are formed on both
sides; but those formed upon the outside remain parenchyma-
tous and are gradually thrown off with the dead outer cortex.
Those upon the inner side develop into the prismatic cells,
mingled with which are cells very like the tracheids, except
that they retain to some extent their protoplasmic contents.
These cells are arranged in more or less well-marked zones, and
possibly mark the limits of each year's growth. It will be seen
from what has been stated that while a true secondary thick-
ening of the stem occurs in Isocfcs, it is quite different from
that in Botr\cJiiimi, which closelv resembles the normal thicken-
ing of the coniferous or dicotyledonous stem. It has been com-
pared to that found in Yucca or Draccrua, and this perhaps is
more nearly like it. However, as the development of cambium
and secondary thickening have evidently occurred independ-
ently in very widely separated groups of plants, it is quite likely
that we have here one more instance quite unconnected with the
same phenomenon elsewhere.

The leaves, as already stated, differ but little from those of
the young plant. The vascular bundle is somewhat better
developed, but remains very simple, with only a few rows of
tracheids fully developed. The vascular bundle of the leaf is
better developed at the base of the leaf, and especially behind
the sporangium (Smith (i)).

The phloem remains undifferentiated, and no perfect sieve-
tubes can be detected. The phloem lies upon the outer side of
the xylem, but shows a tendency to extend round toward the
upper side. Of the Filicine?e, Ophioglossuin comes the nearest
to it in the structure of the bundles. The air-channels are four

XIV

tSOETACEM

555

in number in the fully-developed leaf, and the diaphragms
across them more regular and complete. Instead of being
throughout but one cell thick, as in the first leaves, they are
thicker at the edges, so that in section they appear biconcave.
In the older leaves the broad sheath at the base is much better
developed, and the over-lapping leaf bases give the whole stem
much the appearance of the scaly bulb of many Monocotyledons.

Fig. 32i.—^Isoetes lacustris.

Section of root-apex, showing dichotomy, X about 190
(after Bruchmann).

In all the terrestrial species, and those that are but partially im-
mersed, the leaves are provided with numerous stomata of the
ordinary form ; but in some of the submersed species these are
partially or entirely wanting. The development of the ligule
also varies, being very much greater in the terrestrial species,
where it may possibly be an organ of protection for the younger

leaves.

The ligule in its fully developed condition (Smith (i))
shows four portions: i, a sheath of glandular appearing cells
at its base ; 2, the "glossopodium," consisting of a band of large
empty cells, above which is (3) the main portion of the ligule,
composed of small cells containing protoplasm; 4, the apex,
composed of dead cells.

556 MOSSES AND FERNS chap.

Hofmeister states that in /. lacustris the first sporangia are
not developed until the fourth year from the time the young
sporophyte is first formed. The sporophylls begin to form in
the third year, but it is a year more before the sporangia are
complete. From this time on, the regular succession of sporo-
phylls and sterile leaves continues.

There has been much disagreement as to the method of
growth in the root. The earlier observers attributed to it a
single apical cell, not essentially different from that of the true
Ferns ; this was shown to be incorrect by Bruchmann ( i ) and
Kienitz-Gerloff (6), but Farmer (2) claims that none of these
have correctly described the structure of the larger roots, which
differs somewhat from that of the earlier ones. According to
the latter observer there is always a single initial for the plerome,
and above this two layers of meristem, one giving rise to the
inner cortex, the other to the outer cortex, as well as to the epi-
dermis and root-cap. The fibrovascular bundle is monarch,
like that of Ophioglossiim vidgaUim, and the phloem becomes
differentiated before the xylem elements are evident.

The later roots arise much as the second one does in the
young plant, but the rudiment is more deeply seated. The
roots are arranged in /. lacustris in four rows, two correspond-
ing to each furrow (Van Tieghem (5)). According to
Bruchmann the first evidence of a forming root is a single cell
of the cortical tissue lying a short distance outside of the leaf-
trace. This, however, cannot be looked upon as the apical cell,
as it only gives rise to calyptrogen and dermatogen. The peri-
blem and plerome arise from the cells lying immediately
below it.

The branching of the roots is a genuine dichotomy, and has
also been carefully studied by Bruchmann (Fig. 321). He
states that the process begins by a longitudinal division of the
plerome initial, and each of the new^ initials at once begins to
form a separate plerome. The overlying tissues are passive,
and their divisions are governed by the growth of the two
plerome strands.

The Sporanghim

The development of the sporangium has been studied by
Goebel (3), and more recently by Bower (15), and Wilson-
Smith (i). Each leaf, except the imperfect ones that sepa-

XIV

ISOETACE^'

557

rate the sporophylls of successive years, bears a single very large
sporangium, situated upon the inner surface of the expanded

base.

According to Goebel (3) the young sporangium consists of
an elongated elevation composed of cells which have divided by
periclinal walls; but both Bower (15) and Smith (i) state that
it can be traced back to a small group of strictly superficial cells
which later undergo periclinal divisions.

Fig. 322. — Isoetes echinospora. A, section of young sporophyll, X32S; h ligule; the
sporangial cells have the nuclei shown. B, section of part of a young macro-
sporangium, X32S; the sporogenous cells have the nuclei shown. C, cross-section
of the base of a young sporophyll, with microsporangium, X25; v, the velum; vb,
vascular bundle; the trabeculae are left unshaded. (After Wilson-Smith).

The very complete account of the development of the spo-
rangium of /. echinospora made by Wilson-Smith ( i ) differs
in some important details from that of Goebel. The first peri-
clinal division, while it may separate a definite parietal layer,
does not, as a rule, do this; but there are further periclinal
divisions in the superficial layer of cells which add to the spo-
rogenous tissue, much as is the case in Eqiiisetuui and Ophio-
glossum. There is not, therefore, the early and definite segre-
gation of the archesporium described by Goebel, nor do the
archesporial cells remain independent, as Goebel states is the
case in /. laciistris.

Wilson-Smith finds a complete absence of the regular

558 MOSSES AND FERNS chap.

arrangement of the cells described by Goebel. He says (1. c,
p. 241 ), ''I am forced to conclude that the sporangium-of Isoetes
(at least of /. cchinospora and /. EngcUnanni) just as the
microsporangium of Angiosperms, grows as a unit, and not as
a number of individual segments."

The velum appears very early and is apparently developed
directly from a part of the sporangium-fundament — indeed it
looks as if in some cases it actually contrilnited to the sporoge-
nous tissue. The velum reaches its full development before the
rest of the sporangium does. In certain species, some of its
cells, as well as those of the adjacent leaf-tissues, may become
lignified and show spiral and annular thickenings.

In their early stages, there is no difference between micro-
and macrosporangia. Wilson-Smith could find no indication
in the species investigated by him, of the early differentiation
of the two kinds of sporangia described by the early investi-
gators. In both macro- and microsporangia, divisions occur
in all directions, resulting in a very large mass of potential spo-
rogenous tissue. There is later, however, a differentiation of
the archesporial tissue into fertile and sterile areas, the latter
forming later the "trabeculre."

About the time that the last cell-divisions are taking place in
the archesporial tissue, certain regions divide less actively and
react less strongly to stains. These relatively inactive regions
are the sterile ones, and from them are developed the sporan-
gium wall, the trabecular and tapetum, while the- rest of the
archesporial tissue, at least in the microsporangium, develops
spores.

The trabecul?e are more or less irregular masses of tissue,
not forming definite partitions, although they may anastomose
more or less freely (Fig. 2>^^^ C). The cells of the trabecula
become flattened and extended by the subsequent growth of the
sporangium, and lose to a great extent their protoplasmic con-
tents, so that they soon become clearly separated from the inter-
vening sporogenous cells. The trabeculre later undergo a fur-
ther differentiation into a layer next the sporogenous cells, this
outer layer constituting the tapetum, and an inner mass of much
larger and more colourless cells, the tral)ecular proper.

The young tapetal cells do not stain strongly, but later,
when they presumably become active in supplying the young
spores with food, they stain even more strongly than the spo-

XIV

ISOETACEJE 559

rogenous cells. As in Lycopodiiun and Sclaginclla, the tapetal
cells remain intact, instead of being broken down as they usually
are in the Ferns and Eqiiiscfuiii.

In the microsporangium all the sporogenous cells divide,
the divisions being successive and usually resulting in spores of
the ''bilateral" type, although tetrahedral spores are sometimes
formed. The number of spores in each sporangium is very
great. In /. echinospora, it ranges from 150,000 to 300,000.

The Macrosporangium

The earliest stages of both types of sporangium are alike,
but the macrosporangia are recognisable as such earlier than
the microsporangia. In the former, before any distinction of
fertile and sterile tissue is evident, certain cells become notice-
ably larger than their neighbours, and enter into competition, as
it were, to become the spore mother cells. There is apparently
no rule as to either the number or position of these potential
mother cells; but sooner or later some of them outstrip their
competitors, become very large, and ultimately divide into the
four macrospores.

The formation of the trabeculae and tapetum is essentially
the same as in the microsporangium ; but the trabeculae are fewer
and more massive, and the tapetum is several cells in thickness.-
The unsuccessful sporogenous cells probably are used up in the
further development of the growing spores.

The further development of the mxacrospore has been studied
in /. Diirieni by Fitting (i). Preliminary to the first nuclear
division in the mother cell, whose membrane consists of a pec-
tose-compound and not cellulose, there is a division of the starch
granules into two groups which divide again, and the four
starch masses arrange themselves tetrad-wise in a way that
recalls the behaviour of the cell .contents in the dividing spore
mother cells of Anthoccros. The four nuclei resulting from the
repeated division of the primary nucleus are in close contact
with the four starch masses, and there then follows the simul-
taneous formation of cell plates between the nuclei. The cell
plates are replaced by the cell walls which separate the four
young tetrahedral macrospores.

The protoplast of each young spore secretes about itself a
special membrane from which is later developed the characteris-

56o MOSSES AND FERNS chap.

tic perispore. Within the special membrane is d'*iveloped a sec-
ond membrane — exospore — which later shows a division into
three layers. Within the exospore the mesospore and endo-
spore arise very much as in Selaginella, which Isoetes further
resembles in the separation of the mesospore from the protoplast
and from the exospore, although this is less conspicuous than
in SclagincUa.

As the sporangium develops, the surrounding leaf tissue
grows up about it, somewhat as the integument of an ovule
invests the nucellus. Goebel calls attention to the resemblance
between the sporangium of Isoctcs, sunk in the fovea and par-
tially covered by the velum, and an ovule with a single integu-
ment.

Bower finds in the sporangium of Lepidodendron, structures
which resemble the trabeculae of Isoetes, and he is inclined to
consider the two genera as really related.

In /. lacustris the sporangium is sometimes replaced by a
leafy bud which may develop into a perfect plant. (Goebel:
"Ueber Sprossbildung aus Isoetesblatter," Bot. Zeit., 1879).

The relationship of Isoetes to the other Pteridophytes is not
entirely clear, and there has been a good deal of difference of
opinion on this point. In many respects it shows a nearer
affinity to the eusporangiate Ferns, than to the Lycopodinece,
in which the genus is usually included. The archegonium
closely resembles that of Ophioglossum or Marattia, and the
spermatozoids are multiciliate, which is never the case in any
known Lycopod, but is universal among the Ferns. The
anatomy of the sporophyte is quite peculiar, but may, perhaps
be quite as aptly compared to the Fern-type, as to that of the
Lycopodineae. The dichotomous branching of the roots has a
parallel in Ophioglossum, although it must be admitted that it
closely resembles the forking of the root in Lycopodiiim. The
sporangium may perhaps as well be compared to the spike of
Ophioglossum or the synangium of Dancca as to the single
sporangium of Lycopodiiim or Lepidodendron. It would be
rash to assert positively that the trabeculse correspond to the
partitions between the sporangia of Ophioglossum, and that
the sporangium is really compound, but this is not inconceivable.
The position and origin of the large sporangium of Isoetes are
certainly not very unlike those of the sporangiophore of
OpJiioglossum.

XIV ISO ET AC EM 561

The development of the spores and the early stages of the
female gametophyte certainly resemble those of Selaginella,
and form the strongest argument for assuming a relationship
between the two genera. The embryo, however, is very much
more like that of the eusporangiate Ferns, resembling, perhaps,
most nearly that of BotrycJiiuni, and in connection with the
structure of the mature gametophyte and sexual organs, makes
it not improbable that there is a real, but extremely remote rela-
tionship between Isoetes and the Eusporangiatae.

As to the affinities of Isoetes with the Spermatophytes, it
more nearly resembles them in the formation of the female
prothallium than any other Pteridophyte except Selaginella, and
the reduction of the antheridium is even greater than there.
The embryo resembles very much that of a typical Monocotyle-
don, and the histology of the fully-developed sporophyte, the
leaves with their sheathing bases surrounding the short bulb-
like stem, and the structure of the roots, all suggest a possible
relation to the Monocotyledons directly rather than through the
Gymnosperms.

There is, however, a great interval between the flower of
the simplest Angiosperm and the sporophylls of Isoetes, and
more evidence must be produced on the side of the former
before it can be asserted that this relationship is anything more
than apparent.

CHAPTER XV

THE NATURE OE THE ALTERNATION OF GENERATIONS

The origin and significance of the phenomenon of the alterna-
tion of generations, so characteristic of the Archegoniates, and
its bearing npon the origin of the leafy sporophyte of the higher
plants, have been the snl)ject of mnch discussion.

Among the lower plants the phenomenon is not uncommon,
but it is in none of these so prominent as it is among the Arche-
goniates. If the views of Oltmanns (2) are accepted, the
cystocarp of the Rhodophyceae represents a neutral generation,
comparable in a way to the sporophyte of the Archegoniates,
and like the sporophyte of the i\Iuscine?e is parasitic upon the
gametophyte. The fruiting body resulting from the fertilisa-
tion of a carpogonium or archicarp in many Ascomycetes also is
very similar to the cystocarp of the Rhodophyce?e, and might
perhaps with equal propriety be denominated the sporophyte.

The method of development of the sporophyte in these
forms, however, is very different indeed from that of the Arche-
goniates, and does not suggest even a remote homology.

Among the Chlorophyce?e, the alternation of generations is
not conspicuous, but it is nevertheless in this group and not
among the Rhodophyceae that we are to seek the progenitors of
the Archegoniates.

The presence of sexual and non-sexual plants among the
Green Algae is in no way comparable to the alternation of game-
tophyte and sporophyte in the Archegoniates. The same indi-
vidual in Ocdogonium or ]\mchcria may produce either zoo-
spores or gametes, and the production of sexual or non-sexual
cells is largely due to external conditions. (See Klebs (i)).
The product of the fusion of the gametes in these plants is a

resting spore, which on germination, either directly or by the

562

XV NATURE OF THE ALTERNATION OF GENERATIONS 563

preliminary formation of zoospores, gives rise to the new gen-
eration. The primary function of the resting spore (zygote)
is to carry the plant over a period of stress — drought or cold.

The Confervoide?e among the Green Algae are for good
reasons considered to be among living forms the nearest to the
progenitors of the Archegoniates. The germinating zygote in
these plants usually develops several zoospores, each of which
gives rise to a new plant, thus quickly increasing the number
of individuals resulting from a single fertilisation. This is
obviously an advance upon the condition where the zygote gives
rise to but one plant, and this preliminary division of the zygote
probably was the first step in the evolution of the sporophyte or
neutral generation which becomes so conspicuous in the Arche-
goniates.

Among the Confervoidere, Coleochccfe most nearly approxi-
mates the condition found in the lower Bryophytes. Alone
among the Algae the germinating zygote forms a cellular body
or embryo directly comparable to that of Riccia, for example.
Each cell of this embryo-sporophyte then produces a zoospore
which develops into a new plant (gametophyte).

Whether the protective envelope formed about the fertilised
oogonium of Colcochcctc may be considered to be in any way
comparable to the outer cells of an archegonium is doubtful —
at best the resemblance is very remote — and in the character of
the sexual organs there is a very great gap between Coleochccte
and the simplest Liverw^ort.

The zygote of the Green Algse is evidently a provision for
carrying the plant over periods of cold and especially drought —
that is, it is in a sense an adaptation to terrestrial conditions
which the growing plant cannot withstand. From this dormant
unicellular sporophyte (oospore) there has gradually been
evolved the complex, independent sporophyte of the vascular
plants.

The first step in the elaboration of the sporophyte was the
production of several zoospores. The next step is that shown
in Colcochcctc, where there is marked growth of the germinat-
ing zygote and its transformation into a cellular body, or
embryo, previous to the formation of the zoospores. No form
is known among the Chlorophyceae in which the development of
the sporophyte is carried any further.

The transition from the typically aquatic life of the algal

564 MOSSES AND FERNS chap.

ancestors of the lower land plants to the terrestrial mode of life
was probably very gradual. We may still find forms among
the simpler Algse which are to a greater or less degree adapted to
a terrestrial life. Such types as Plcurococcxis, Botrydhim, and
species of Vaucheria may be cited. In Plcurococcus no special
organs for water absorption are developed, and the cells simply
vegetate as long as the surrounding atmosphere is sufficiently
moist, becoming dried up and dormant when the necessary
moisture is lacking. Botrydinm, however, is provided wath a
relatively extensive system of roots, which penetrate the moist
earth and enable the plants to live for a considerable time as a
genuine land plant, since the loss of water due to transpiration
is made good so long as there is an adequate supply of water in
the soil. These Alg?e, however, have no efficient check against
the loss of water in the parts exposed to the air, and very quickly
die w^hen the supply of water from the earth is suspended.

Such Schizophyce?e as Nostoc and similar terrestrial forms,
by the development of the massive gelatinous or mucilaginous
envelope, are protected against rapid loss of water. The gel-
atinous tissues of many sea-weeds, which are exposed for short
intervals to the air, no doubt serve a useful purpose in holding
water. None of these forms, how^ever, can be considered as
verv well equipped for a strictly terrestrial existence.

To judge from the life-history of certain aquatic Liverworts,
such as Ricciocarpus, it seems not unlikely that the primitive
Archegoniates arose from some aquatic Algse, probably not very
unlike Coleochcute. These may have become stranded upon the
mud by the subsiding water, and by the development of rhizoids
which are often induced by such contact with a solid medium,
the activity of the plant would be prolonged until the rhizoids
were unable to extract sufficient moisture from the soil to supply
the needs of the plant. To judge from the analogy of Riccio-
carpus, this contact wnth the soil is a stimulus to a much more
vigorous growth than is the case when the plant is floating, and
we can conceive that the vegetative vigour of the Alga might
have l)een enhanced by its new terrestrial mode of life.

The direct origin of the simple gametophyte of such a Liver-
wort as Ancura or Anthoceros, from some confervoid type is
readily conceivable, but the very great difference in the com-
plexity of the reproductive organs between even the simplest

XV NATURE OF THE ALTERNATION OF GENERATIONS 565

Liverwort and any known Alga forbids the assumption of any
but a very remote connection between them.

In all typical Liverworts w^hich are characteristically terres-
trial plants, in addition to the rhizoids for absorbing water,
there is also a more or less perfect cutinisation of the superficial
cells which materially checks the loss of water from transpira-
tion. In addition to this there are often special provisions for
protecting the plants from injury by drought. Most species
have mucilage secreting organs of some kind, and the hairs and
scales frequently developed upon the plant are usually associated
with water storage. Like some Algae, certain Liverworts can
become dried up without injury, reviving promptly when sup-
plied with water. Less frequently special tubers are formed,
these being especially marked in some species from dry regions,
like those about the Mediterranean or in Southern California.

In passing from an aquatic to a terrestrial habitat, another
change of structure must be noted, namely, the development of
mechanical tissues for giving the plant body the necessary sup-
port in the much rarer medium of the atmosphere. In studying
the evolution of the gametophyte in the Bryophytes, it becomes
at once evident that the development of mechanical tissues is
largely obviated in the lower types by their never attempting to
stand upright, but they lie prostrate upon the ground as we may
assume was done by their algal prototypes. This prostrate
position, while doing away with the necessity for skeletal tissues
also has the advantage of offering a much larger surface for
the development of the rhizoids, and also exposes a smaller sur-
face directly to the air and consequently reduces the loss of water
by evaporation. Most of the lower HepaticcT and all the
Anthocerotes have retained this primitive type of gametophyte.
In the Mosses, however, the prostrate thallus is replaced by a
definite leafy axis, which is often upright and may develop a
fairly complete system of skeletal tissues. This type realises
its most perfect expression in such large Mosses as Polytrichum
and Dawsonia. We find in these that in addition to the
mechanical elements, there are also water-conducting tissues,
comparable to the tracheary tissue of the vascular plants,
although in one case we have to do with gametophytic struc-
tures, in the other with sporophytic ones. In these large
Mosses, the rhizoids are multicellular, and may be twisted into

566 MOSSES AND FERXS chap.

cable-like strands, which simulate true roots, but are less
efficient than these.

The size to which the gametophyte may grow depends
largely upon the water supply, which must be regarded as the
most potent factor governing the development of the plant
body. It is evident that the delicate rhizoids alone are insuf-
ficient to supply with water a plant of any but the most modest
dimensions. Indeed, in many Bryophytes, the rhizoids play
but a minor part in supplying water, as the whole plant may
absorb water much as an Alga does. So also we find very few
Bryophytes in which the development of mechanical tissues is
sufficient to make the plants (except small ones) stand firmly
upright. Either the plant is prostrate, or it maintains its up-
right position by virtue of the mutual support offered by its
neighbours, most of the large Mosses growing in dense tufts

or mats.

It is evident that the size to which a terrestrial gametophytic
structure can grow is necessarily limited, owing to its inade-
quate means of obtaining water. Either the plant must grow
where there is a permanent and abundant water supply, or else
it must dry up and completely cease its activity during periods
of drought. It would seem as if the originally aquatic gameto-
phyte could never adapt itself perfectly to terrestrial conditions,
and upon the sporophyte devolved the development of a differ-
ent plant-type adapted from the first to life in the air. As the
sporophyte assumed the character of an independent plant, it
gradually replaced the gametophyte as the predominant struc-
ture of the higher plants.

The origin of the sporophyte of the Archegoniates, as w^e
have seen, is to be sought in the zygote of some Green Alga.
This in its simplest form is a single thick walled resting spore,
adapted to resisting drought, and changes of temperature which
are fatal to the growing plant. Erom its very nature, it is
primarily the terrestrial phase, so to speak, of these typically
aquatic organisms. The embryo-like cell mass developed in
Colcochcutc mav very properly be compared to the embryo-
sporophyte of Riccia, or of any Liverwort. However, each
cell of tiie rudimentary sporophyte of Colcnchcrfc produces but
a single spore, and this is a zoospore like those of other Algae,
and is-clearly associated with the normally aquatic habit of these
plants.

XV NATURE OF THE ALTERNATION OF GENERATIONS 567

In the simplest sporophyte of the Liverworts as ihustrated
by Riccia, there is first the separation of the superficial layer of
sterile cells, about the central mass of sporogenous tissue, and
each cell of the latter produces four thick-walled resting spores,
corresponding physiologically to the single resting spore of the
Alga. The retention of the zygote within the archegonium and
the parasitic habit of the embryo developed from it enables the
sporophyte to reach a much larger size than is possible where
the germination is entirely at the expense of the food-materials
stored up within the spore, as is necessarily the case where the
zygote becomes free before germination, as it does in all the
Chlorophycese. When to this is added the division of each spo-
rogenous cell into four spores, it is clear that the output of
spores resulting from a single fertilisation is very much
increased, a great advantage for a terrestrial plant in w^hich the
conditions for fertilisation may not occur very often.

The formation of the spores in tetrads is common to all
Archegoniates, and it is preliminary to this division that there
occurs the reduction in the number of the chromosomes v^hich
has been observed in a number of cases. While this reduction
is not always strictly definite, it is found that the spore has
approximately one-half the iiumber of chromosomes which are
found in the vegetative cells of the sporophyte, and this reduced
number, of course, is transferred to the tissues of the gameto-
phyte w^hich arises from the germination of the spore. When
the gametes fuse, the zygote-nucleus receives the combined
chromosomes of the gametes, and the sporophytic cells de-
scended from it contain the double number of chromosomes.

We must assume that in its primitive form the sporophyte
of the first Archegoniates was composed exclusively of spo-
rogenous tissue, as it is in Colcochcctc. Riccia show^s the first
indication of the sterilisation of the outer layer of sporogenous
tissue. Professor Bower (16) has called attention to the great
importance of the principle of sterilisation of potentially spo-
rogenous tissue in the evolution of the sporophytic structures
among the Archegoniates

The next step in the evolution of the sporophyte, as it is
seen in the Liverworts, is one of great importance in the further
evolution of the sporophyte. This is the sterilisation of the
whole of the basal part of the sporophyte, which assumes the
important role of a special organ of absorption, or haustorium.

568 MOSSES AND FERNS chap.

The foot is an absorbent organ of great efficiency, and through
it the growing embryo is nourished at the expense of the
gametophyte, upon which the embryo hves much as a parasitic
Fungus does upon its host. This development of a special
absorbent organ at once allows a longer period of growth for
the embryo, and a correspondingly greater development of spo-
rogenous tissue.

The next evidence of progressive sterilisation in the tissues
of the sporophyte is the development of an intermediate region,
the seta, and the sterilisation of some of the sporogenous tissue
to form elaters. Both of these developments, however, are
concerned solely with the dissemination of the spores. In the
more advanced sporophytes of most Liverworts, the cells
develop more or less chlorophyll, and to this extent the sporo-
phyte is capable of self-support. The sporophyte, however,
remains dependent to a great extent upon the gametophyte,
from which, by means of the massive foot, it receives most of
its nourishment.

The first marked evidences of a capacity for independent
existence in the sporophyte are found among the Anthocerotes
and the Mosses. In these classes, the sterilisation of the spo-
rogenous tissue is carried much further than in any of the
Hepaticse, and much the greater part of the sporophyte is com-
posed of sterile tissue. In such forms as Anthoccros and
Funaria, the sporogenous tissue forms but a small fraction of
the whole sporophyte, which grows for several months and
develops an extensive and efficient system of tissues for photo-
synthesis. Conducting tissues are also present, and in the
Mosses the seta and capsule have conspicuous mechanical tissues
as w^ell. The sporophyte, nevertheless, receives its water sup-
ply from the gametophyte through the foot, as it does in the
Liverworts.

With the establishment of a true root putting the sporophyte
into direct communication wnth the earth, the independence of
the sporophyte is completed. Whether the direct contact w^ith
the earth acted as a stimulus to vegetative activity, as it seems
to have done in the case of the transference of the gametophyte
from water to land, of course we can only conjecture ; but the
extraordinary complexity of the sporophyte wdiich is found in
all Pteridophytes indicates that this is not improbable. With
the establishment of the sporophyte as an independent, typically

XV NATURE OF THE ALTERNATION OF GENERATIONS 569

terrestrial plant, the gametophyte becomes more and more sub-
ordinated, finally serving merely to develop the reproductive
organs and to nourish the young sporophyte until it can take
care of itself.

While it must remain conjectural just how^ the first true
root arose, the most probal)le explanation is that it was a modi-
fication of part of the foot. The foot is from its first inception
peculiarly an absorbent organ, acting much as the haustorium of
a parasite would do, and taking from the gametophyte the water
and food necessary for the growth of the sporophyte. The
foot, like the true roots developed later in the history of the
sporophyte, is a very difTerent organ from the delicate rhizoids
of the gametophyte, and much more efficient for supplying a
massive structure like the sporophyte with the water necessary
for its growth. Moreover, as soon as a true root was estab-
lished, provided with an apical meristem for prolonged growth,
it could keep pace with the increasing size of the sporophyte,
and by the subsequent development of similar secondary roots
of increasing size and complexity, a root S3^stem was established,
to whose further development there was no apparent limit.

So soon as the sporophyte was emancipated from its depend-
ence upon the gametophyte, a new plant-type, essentially ter-
restrial in its nature, was established. This was not a trans-
formed aquatic organism, like the gametophyte, but the elabora-
tion of a structure essentially adapted to an aerial existence from
the beginning. To the zygote of some Alga, a resting spore
developed to carry the plant over a period of drought, can be
traced, step by step, by growth and specialisation, the complex
sporophyte as it exists among the vascular plants.

This view of the origin of the leafy sporophyte from the
zygote of some aquatic algal ancestor is the so-called Anti-
thetic theory of alteration of generations. It assumes that the
two generations are essentially distinct, the gametophyte rep-
resenting the primitive aquatic phase, the sporophyte the sec-
ondary terrestrial condition, arising from the germinating
zygote. The sporophyte in its earliest condition was simply a
spore-bearing structure for the multiplication of the gameto-
phyte ; later is gradually assumed the character of an independ-
ent plant, of essentially terrestrial habit.

Opposed to this view is the theory of Homologous Alterna-
tion. This theory was first championed by Pringsheim (3),

5/0 MOSSES AND FERWS chap.

but more recently has been advocated l)y Scott (3), Coulter
(i), and others. This view maintains that the sporophyte
arose as a modification of the gametophyte, and not as an essen-
tially new structural type. The homologous theory of alterna-
tion is based largely upon the phenomena of apospory and
apogamy, and also, to a lesser extent, upon experiments in
regeneration. Pringsheim showed that the protonema of a
Moss might arise from the cut end of the seta, as well as from
the tissues of the gametophyte, a case of apospory, but as yet
there are no instances known of the converse, i. c, the origin
of the sporophyte in the Mosses by apogamy. Pringsheim
believed that the protonema is not essentially dififerent from the
vegetative tissues of the sporophyte from which it might be
made to develop, and that therefore no line can be drawn
between strictly gametophytic and sporophytic structures. It
must l)e remembered, however, that the protonema normally
develops from certain sporophytic cells (spores), and its devel-
opment under abnormal conditions from other sporophytic tis-
sue is not inexplicable. It is, moreover, a significant fact that
the cells of the seta, from which the protonemal filaments arise,
a fact which Pringsheim himself recognises, correspond in posi-
tion to the sporogenous tissue of the capsule, and are probably
homologous with them. The phenomenon of apospory in cer-
tain Ferns is comparable, to that in the Mosses, and recently Lang
(4) has been able to induce in Anthoceros a development of
structures which seem to be rudimentary gametophytes. The
origin of these in all cases was not clear, but they seemed usually
to arise from the outer tissues of the sporophyte. and not from
the sporogenous layer. Stahl ( i ) also found that protonema-
formation might arise from the parietal region of the capsule
in Ccratodon.

The strongest argument in favor of homologous alterna-
tion is the phenomenon of apogamy, or the origin of the sporo-
phyte as a vegetative bud upon the gametophyte, and apospory,
or the origin of the gametophyte by budding from the sporo-
phyte. Apogamy has been observed in a number of species
of Ferns belonging to the PolypodiacetT, Hymenophyllaceae,
and Osmundacece. How far apogamy may be considered a
natural phenomenon, and how far it is a pathological condition
induced by artificial means, needs further elucidation. It
undoubtedly in some species like Ptcris crctica entirely super-

XV NATURE OF THE ALTERNATION OF GENERATIONS 57i

sedes the sexually formed sporophyte, as in this species, appar-
ently, archegonia are never formed. (Sadebeck (8), p. 34.)
In other cases, both apogamous and normal sporophytes are
known. Lang (3) has found that exposure to strong sunlight
will sometimes induce apogamy. Apospory (Bower (6) ) may
consist of the transformation of sporangia into prothallia, or in
some cases the latter may arise from sterile leaf-tissue, even
from leaves which bear no sporangia.

Bower has pointed out that all known cases of apogamy
occur among the leptosporangiate Ferns, admittedly the most
recent and specialised members of the class. If apogamy is to
be looked upon as a reversion to a primitive condition, it is hard
to understand why it should be absent in the other more primi-
tive Pteridophytes. It must be admitted, of course, that these
forms have not received the same amount of study as the higher
Ferns, and it is quite possible that apogamy may be shown to
occur in some of them.

Lang (1. c.) has suggested that the origin of the sporophyte,
assuming the homologous theory of alternation, may have been
something as follows: The primitive gametophyte of the
Pteridophytes was probably a flat thallus that under stress of
circumstances, owing to an insufficient water supply, may have
given rise to spores, the spore stage following the sexual stage,
but being an integral part of the gametophyte. and not produced
from the ovum. In connection with this special spore-produc-
ing function, the structure gradually assumed the character of
a leafy shoot, and later became replaced by a similar structure
which arose from the fertilised ^gg.

It is not made clear, however, how the originally apogamous
sporophyte came to be transferred to the archegonium, nor why
the spores produced from it should so exactly resemble those
developed from the sexually produced sporophyte of the Bryo-
phytes, which according to the "homologous theory of alterna-
tion has nothing to do with the sporophyte of the Ferns.

Although many Bryophytes normally are subjected to all
the conditions which should, according to Lang s theory, induce
apogamy, no instances are known among them of such
apogamous production of spores, or anything resembling in
the remotest degree the normal sporophyte. Either the whole
gametophyte dries up and revives when water is applied, or
else special tubers are developed which survive the dry period.

572 MOSSES AND FERNS chap.

In the few Ferns in which perennial prothallia are formed, e. g.,
Gymnogranunc triangularis, G. {Anogranunc) leptophylla, the
behaviour of the gametophyte is precisely the same as in the
Liverworts.

Coulter has suggested that the determining factor in the
development of the leafy sporophyte has been photosynthesis or
''chlorophyll work." He sees no reason why such a structure
as the leafy sporophyte may not have arisen non-sexually in
response to the need for increased chlorophyll activity, quite
apart from the production of spores. The spores would find
more favourable conditions upon a leafy shoot than upon the
thallus.

It is doubtless true that the production of a large leafy
shoot would be advantageous in increasing the output of spores ;
but why this leafy shoot should not have developed gradually
from the sexually produced sporophyte of some bryophytic
prototype, as there is the strongest evidence that it has done,
is not made clear. The development upon the leaves of the
sporophyte of spores of the same type as those of the lower
Archegoniates is entirely comprehensible if it is admittted that
the sporophyte of the Fern is descended from the leafless sporo-
phyte of some ancestral Bryophyte; but it is very hard to
explain if we assume that there is no genetic connection between
the spores of Bryophytes and Pteridophytes.

According to Coulter's hypothesis, the leafy sporophyte
originated by budding comparable to that of the leafy shoot of
a Moss from the protonema, or the apogamously produced spo-
rophyte of a Fern. The leaves were originally purely vegeta-
tive organs, and the development of sporangia was secondary.
The germination of the asexual spores and the zygote are
assumed to have been the same, each giving rise to a thallus
upon which arose secondarily the leafy shoot.

If such were really the course of development, it is strange
that no trace of the thallus-stage has persisted in the embryo-
sporophyte. The only structure which could possibly be so
interpreted is the suspensor in Lycopodium and SclagincUa,
which most morphologists would hesitate to consider of such
nature.

The statement (Coulter (i), p. 56), 'Terhaps such a tend-
ency (/. e., the elimination of the thallus portion of the zygote
product) is no more difficult to understand than the fact that

XV NATURE OF THE ALTERNATION OF GENERATIONS 573

the spore produces a gametophyte .... and a zygote produces
a sporophyte ....," can hardly be admitted. The spores of
all Archegoniates, if we admit the antithetic theory of alterna-
tion, are the direct descendants of those produced by the germi-
nating zygote of the ancestral form, where also the product of
germination is not directly a new gametophyte, but spores from
which the latter arises secondarily, as is the case in the Arche-
goniates. This is readily demonstrable, while on the other
hand, the development of any type of spore in the least resem-
bling those of the sporophyte is absolutely unknown in any
gametophytic structure.

If it is admitted that the leafy sporophyte originally arose
as an apogamous bud, it would necessarily follow that the foli-
age leaves are more primitive than the sporophylls. and that
there is no genetic connection between Bryophytes and Pterido-
phytes; at present, however, it seems to the writer that the
weight of evidence is very much against such a supposition.

That chlorophyll activity has been a very potent factor in
the evolution of the plant-body is of course beyond dispute, but
its bearing upon the origin of the higher land plants is not so
clear. All green plants, whether aquatic or terrestrial, must
provide for photosynthesis, and we find the arrangements for
the most favorable exposure of the green tissue brought about
in various ways. Leaves are by no means confined to land
plants, many Algae, especially the large Laminariace?e and
FucacCcT having large and perfect foliar organs, which, al-
though of simple structure, are very efficient organs for photo-
synthesis. The independent development of the leaves in sev-
eral groups of Bryophytes shows no evident connection with
adaptation to a terrestrial environment.

If one were seeking among the Bryophytes a structure which
most nearly simulated the leafy Fern-sporophyte, it would be
found in such thallose Liverworts as Symphyogyna or Hymeno-
phyton, whose repeatedly forked thallus resembles superficially
to an extraordinary degree the fan-shaped leaf of a small Fern.
It is conceivable that when the sporophyte first developed a
leaf, the latter might tend to assume the dichotomously
branched form so common in the gametophyte of the lower Liv-
erworts and of the Ferns also which presumably have arisen
from similar forms.

Looking at the evidence from all sides, it seems to the writer

574 MOSSES AND FERNS chap.

that the weight of evidence is very much in favour of the
antithetic theory of the aUernation of generations, and that
there is a real genetic connection between Bryophytes and
Pteridophytes. The sporophyte of the latter is directly
descended from some bryophytic ancestral form, although it
is quite probable that the existing Pteridophytes may have
been derived from more than one ancestral type. All of the
Archegoniates agree closely in their most important structural
details. The sexual organs and method of fertilisation, and the
early divisions of the embryo, are very much alike in all of
them. There is evident in all of the higher Bryophytes a tend-
ency to a subordination of the sporogenous function to the
vegetative existence of the sporophyte, with the development of
conducting and assimilating tissues comparable to those in the
sporophyte of the vascular plants. Finally, the spores produced
by the sporophyte are identical in structure in the two series of
archegoniate plants.

The really weighty argiunent on the other side is the occur-
rence of apogamy and apospory. As to the significance of
these phenomena, they may probably be compared to the adven-
titious budding, so common in many of the higher plants. In
both Pteridophytes and Spermatophytes, the whole sporophyte
may arise by budding from almost any portion of the plant-
body. Thus in Campfosorns or Cystoptcris bulbifcra, the
young sporophyte arises from the leaf, as it does in Begonia or
Bryophyllum among the Spermatophytes. In OphiogJossuin it
may arise from the root-apex, a condition paralleled among the
Spermatophytes by the production of root-buds or suckers in
Popuhis or Anemone. Certain supposed cases of parthen-
ogenesis in the Spermatophytes have been shown to be rather
cases of budding from the nucellar (sporangial) tissue, and
many other instances could be cited showing similar conditions.

No morphologist has ever regarded such adventitious origin
of the sporophyte as indicating in any sense of the word a rever-
sion to a primitive condition. It is not argued that because the
sporophyte may arise as a bud from a root, that therefore the
sporophyte originated first as a modification of a root. In the
same wav, it does not seem reasonable to aro-ue from the doubt-
fully normal phenomenon of apogamy that the sporophyte
developed in the first place as a vegetative modification of the
gametophyte.

XV NATURE OF THE ALTERNATION OF GENERATIONS 575

Farmer's recent remarkable studies on apogamy (Farmer
(10)), show that nuclear fusions occur, indicating that a stim-
ulus, equivalent to fertilisation, is necessary for the develop-
ment of apogamous structures.

It would seem then, that the adaptation to strictly terrestrial
conditions, and the consequent necessity for providing an ade-
quate water supply, is the real clue to the causes for the develop-
ment of the leafy sporophyte. All Bryophytes retain to some
extent the character of aquatic plants, most of them being able
to absorb water at all points, and relying only to a limited extent
upon the rhizoids. Moreover, the latter are entirely inadequate
to supply a plant-body of large size, which could not, of course,
absorb sufficient water for its growth from the atmosphere.
Nature has apparently made numerous attempts to adapt the
essentially aquatic gametophyte to an aerial existence, with only
partial success.

The sporophyte, at first purely a spore-producing structure,
was from its inception essentially an aerial organism. Its
water supply from a very early period was furnished through
the agency of the massive foot, which drew upon the gameto-
phyte for its supply, and formed a much more efficient haus-
torium than the rhizoids of the gametophyte. Later was
developed a true root, probably a modification of the foot, but
unlike the latter, connecting the sporophyte with the earth.

With the appearance of the first true root, the emancipation
of the sporophyte is complete, and as the root system develops
to keep pace with the aerial parts of the sporophyte, a true ter-
restrial type of plant is encountered for the first time. The
appearance of the first genuine green land plants may be con-
sidered the most momentous epoch in the whole history of the
Plant Kingdom.

CHAPTER XVI

FOSSIL ARCHEGONIATES

While the geological record is necessarily very incomplete,
nevertheless a study of the fossil forms has been of great assist-
ance in understanding the relationships of the existing Arche-
goniates.

Unfortunately the simpler, and presumably the older, types
are too delicate in structure to have left any recognisable fossil
remains, except in a very few cases ; and this is true also of
the more perishable structures, such as the gametophyte of the
higher forms.

In spite of the very fragmentary nature of the fossil re-
mains, some of these are so complete that our knowledge, even
of the internal structure of some of the extinct types, is extra-
ordinarily accurate, and the researches of the past two decades
have thrown much light upon the geological history of the
higher Archegoniates.

The fossil remains are of two kinds — casts and petrifac-
tions. The former, of course, can give information only as to
the external characters, but these impressions are in many in-
stances beautifully clear, and the nature of the plants unmis-
takable. True petrifactions are of much rarer occurrence, but
where they do occur, the internal structure of the petrified plant
can often be made out with great exactness. The infiltration
of mineral substances completely replaces the cell walls, and
thin sections of such petrifactions show most beautifully the
character of the tissues. Silica, calcium-carbonate, iron pyrites
among other substances are the causes of these petrifactions.
This petrifaction may take place on a large scale, as is seen in
the petrified forests of Arizona and California. For a full ac-
count of the conditions under which fossils have been formed,

576

XVI

FOSSIL ARCHEGONIATES S77

the reader is referred to Professor Seward's "Fossil Plants"
(Seward (i), Chap. IV). By grinding thin slices of these
petrified tissues, they may be examined microscopically with as
much ease as sections taken from living plants, and it is largely
to a critical study of such petrified tissues that the affinities of
many doubtful forms have been determined.

In some of the later formations delicate plants, like Mosses
and Liverw^orts, have been preserved in amber, and of course
in these cases, there is no question of the nature of the plants ;
but no such fossils occur in the older formations, and none of
those discovered are essentially different from their existing
relatives, and of course throw no light upon the early history
of the Archegoniates.

The fossil remains of the lower plants are for the most part
extremely meagre, and throw little light upon the evolution of
the Archegoniates. Presumably the progenitors of the lower
Archegoniates were simple Green Algae, but such extremely
perishable organisms can hardly be expected to have left recog-
nisable remains in the older rocks. Some of the calcareous
Algse like the Characese, certain Siphoneae and Corallines, are
know^n from very old strata, and there is every reason to be-
lieve that the less specialised Confervoidese, which probably are
nearer the lower Archegoniates, were also abundantly repre-
sented in the earlier geological epochs, although they have left
no recognisable fossil traces. The delicate nature of the prim-
itive Hepaticse fully explains their absence from the earlier
strata, and the same is true of the gametophyte of the Pterido-
phytes.

Fossil MusciNE^ {Seward {i), Chap. VIII)

The fossil remains of Bryophytes are too scanty in number
and of too doubtful authenticity in most cases to be of much
value in determining the geological history of the group.
Liverworts are too delicate to leave fossil traces except under
most exceptional conditions. In the Tertiary and later forma-
tions they are occasionally met with, but all the forms discov-
ered are closely allied to existing species, and throw no light
upon the origin ot the Hepaticse. Of the few unmistakable
fossil Hepaticse, may be mentioned Marchanfifes Sczannensis,
of Oligocene Age. This is evidently close to the living genus
2>7

5/8 MOSSES AND FERNS chap.

Marchantia — perhaps identical with it. From the amber of
North Germany, also of the Oligocene, a number of Liverworts
have been described, all being referred to living genera, e. g.,
FruUania, Jiiiigcnnannia.

The higher I^Iosses might be expected to leave more evident
traces than the more delicate Liverworts; but although many
moss-like fragments have been described, the real nature of
most of them is doubtful, as they are for the most part merely
impressions and might very well belong to other plants than
Mosses. While it is extremely probable that some of the
species of ''Muscitcs" are real Mosses, and that Mosses were
present in the Palaeozoic formations, it cannot be said that our
knowledge of these forms is very satisfactory.

Some of the larger Alosses, like Polytricluini and Hypnum,
might very well be preserved fossil; but unfortunately their
resemblance to the shoots of small Lycopods, or even of some
Conifers, is so close that their identification from impressions
is practically impossible. Except in the later formations no
trace of the characteristic sporogonium has been found, and
even in the few instances from the later formations, the real na-
ture of the fossils is not beyond question. While it is reason-
able to suppose that both Liverworts and Mosses occurred in
the Palaeozoic formations, there is no certain evidence of this
from the geological record, and such fragments as do occur in
the Palaeozoic rocks are too uncertain to throw any light upon
the origin of the JNIuscineae.

Fossil Pteridophytes

The firm tissues of the sporophyte in the Pteridophytes are
much more resistant than the soft tissues of most Bryophytes,
and consequently far better fitted to be preserved in a fossil con-
dition. Remains of undoubted Pteridophytes occur from the
Silurian, and in the Devonian and the succeeding Palaeozoic
formations they constitute the predominant ])lant types. It is
evident from a study of the fossil remains that all the existing
classes were well differentiated as far back as the record ex-
tends: but in addition to these, there were a number of types
which have become- extinct, the exact affinities of some of which
are not entirely clear.

XVI FOSSIL ARCHEGONIATES 579

Filicinecu (Potonie (j); Scott (/))

The great majority of the fossil remains of Ferns are in the
forms of impressions, but these are frequently of great clear-
ness, the numerous Carboniferous fossils being especially beau-
tiful, and showing all the external characters most perfectly.
As these impressions are usually of sterile leaves, the first at-
tempts to classify them were based upon the venation. While
the venation is a diagnostic character of importance, it cannot
be relied upon exclusively, as it sometimes happens that two
nearly related forms, c. g., Onoclca scnsibilis and O. striithi-
opteris, have a very different type of venation. On the other
hand, the Cycad, Stangcria, has a venation so much like that of
a Fern that the sterile plant was at first described as a species

of Lomaria.

The more recent students of fossil plant remains have relied
much more upon a study of the sporangia and of the tissues as
disclosed by sections of petrifactions, and the results of these
studies have added very materially to our knowledge of the
affinities of the Ferns as gathered from a study of the structure
of the living species, and have throwai much light upon the his-
tory of the fossil forms.

The earliest undoubted remains of Ferns occur in the Si--
lurian. Of the few fossils of this age which can with reason-
able certainty be assigned to the Filicinese may be cited the
genus Rhodea, a Fern with finely dissected leaves, not closely
resembling any existing type. In the Devonian a number of
characteristic genera occur. Among these may be mentioned
Cardiopteris, Sphcnopteridium, Adiantites and Archcuopteris

(Palcuopteris.)

During the Carboniferous the Ferns increase rapidly in
number and variety, and constitute with the other Pterido-
phytes the predominant vegetation of the period. In the Sec-
ondary and Tertiary formations, they become less prominent,
giving way to the rapidly increasing Spermatophytes ; but
they have persisted to the present time in large numbers, and
have held their own much better than the other two classes.

In studying the venation of the earliest Ferns, especially
the Arch^opteridse of Potonie, it is found that they all corre-
spond to a type found at present in comparatively few Ferns

58o MOSSES AND FERNS chap.

The leaflets show no midrib, and are usually more or less fan-
shaped with radiating, dichotomously branched veins.

A similar type of leaflet is found in some existing species
of Botrychium, e. g., B. hinaria, and also in species of Schhcca,
Trichomanes, Aneimia, and Adiantnm. This type of venation
occurs in the cotyledon of most Ferns, and is probably to be
considered a more primitive one than the pinnate venation of
the typical Ferns. Two other characteristic types are the 'Tc-
coptcris" and the ''Sphcnoptcris" types, which are represented
in many recent Ferns. The first, which differs from the others
in having the pinnules sessile, by a broad base, is especially
common in the Cyatheacece, which includes most of the living
tree-Ferns,

The netted venation seems to be the most recent type of all,
and Potonie states that it is first met with in Mesozoic fossils.

The dichotomous branching of the leaf itself also seems to
be a primitive condition, and is relatively more common among
the Palaeozoic types than in those of the present. There are,
however, many examples among existing species, and it is the
usual form in the cotyledon. Glcichcnia, ScJii:;<ra, TricJio-
mancs, Matonia, Adiantnm, are among the modern genera in
which this occurs. The Palaeozoic Ferns also show not infre-
quently a condition intermediate between dichotomous and pin-
nate leaves.

Another peculiarity of these ancient Ferns is the frequent
development of subsidiary pinnae between the ordinary ones.
These are rare in modern Ferns, but are known in a few cases,
e. g., Gleichcnia gigantea, Hcmitclia capcnsis.

In the oldest fossils in which the sporangia have been de-
tected, these are confined to special leaves, or leaf-segments, as
they are in the living Ophioglossaceae and Osmundaceae.
These fertile leaf-segments are quite destitute of a lamina, and
are completely covered by the sporangia. This condition of
things is an interesting confirmation of the view which con-
siders the Ophioglossaceae as the most primitive existing type
of Ferns. This view holds that the primitive Fern type must
have developed the sporangial portion of the leaf before the
lamina appeared, a condition now known to exist in the curious
Ophioglossnm simplex.

The Devonian genus Archccopteris, for example, closely re-
sembles Botrychium, except that the fertile part of the leaf is

XVI FOSSIL ARCHEGONIATES 581

terminal instead of arising from the face of the leaf. In Ophio-
glossiim, however, a study of the earlier stages of the fertile
leaf makes it not improbable that the spike may be interpreted
as a truly terminal organ, and the sterile segment as a lateral
appendage of it, comparable to the condition in Archcuopteris.
Dimorphic leaves are of common occurrence also in the later
Palaeozoic Ferns.

From the numerous studies that have recently been made
upon the stem-structure of the fossil Ferns, it appears (Scott
(i), p. 303) that the monostelic stem is relatively commoner
among the Palaeozoic Ferns than it is at present. Among the
existing Ferns, monostelic stems are especially characteristic
of the Gleicheniaceae, Hymenophyllaceas, and most Schizseaceae.
There were, however, many Palaeozoic Ferns in which the stem-
structure closely resembled that prevailing among living Ferns.
Some stems closely resembling those of modern tree-Ferns have
been described under the name Psaronius. A study of the
leaves and sporangia of these shows that their affinities were
with the Marattiaceae rather than with the Cyatheaceae, to which
family belong nearly all the living tree-Ferns.

The characteristic sporangia of Ferns are the most certain
means of determining their affinities, and unless these are
known, the identification of the fossils must be more or less
doubtful. While fossil sporangia are of comparatively rare
occurrence, still enough has been made out concerning the na-
ture of the sporangia of the fossil Ferns to make perfectly clear
the affinities of many of these with the living forms.

As might be expected from a comparative study of the ex-
isting Filicineae, it is found that the Eusporangiatae, while
showing every indication of being more primitive than the
Leptosporangiatae, are really much older geologically. While
at the present time these constitute probably less than two per
cent, of the living Ferns, among.the Palaeozoic fossils they far
outnumber all others, if they do not actually include all Palae-
2oic Ferns.

Of the two living families, Ophioglossaceae and Maratti-
aceae, it is the latter which is especially abundant in a fossil
condition. Whether the scarcity of the Ophioglossaceae as
fossils is due to their lack of firm tissues in the leaf, or whether
the living forms have become more modified than the Maratti-
aceae, it is not possible to decide. The former view seems to

582 MOSSES AND FERNS chap.

the writer the more probable, as there are very strong reasons
for considering the type of sporangium found in OpJiioglos-
sum as the most primitive occurring in the Fihcineae.

Very few fossils have been found that can be referred with-
out hesitation to the Ophioglossace?e. The early Palaeozoic
genera Rhacoptcris and Archccoptcris were apparently very
much like BotrycJiiitui, but it is by no means agreed by all
Pal?eobotanists that they really were related to the Ophioglos-
saceae. There are also other Paheozoic genera, which perhaps
are quite as much like Botrychhim as they are like the Marat-
tiacece, with which they are usually associated, but all of these
forms are very doubtful. OpJiioglossifcs oiifiqua from the
Permian is said to resemble closely the spike of Ohiloglossiim,
and Chiroptcris digit at a from the upi)er Triassic has been com-
pared to O. paUnatuin. In a later formation (Eocene) there
has been found a species of Ophioglossinn, O. ococenum
(Potonie (3), p. 91).

If the existence of the Ophioglossaceae during the earlier
geological epochs is somewhat doubtful, this cannot be said of
the second family of the Eusporangiatse, the Marattiacese.
These evidently comprised the greater part of the Palaeozoic
Ferns, and many of them were very much like their living de-
scendants. The few existing Marattiaceae are mostly tropical
Ferns, some of great size, such as most species of Marattia and
Angioptcris.

The ]\Iarattiaceae have much firmer leaves than the Ophio-
glossaceae, with distinct and conspicuous venation, admirably
fitted to leave a clear impress in the rocks, and indeed the casts
of these, in many cases, might almost have been made from
leaves of the living species. The close relationship of many of
these fossil IMarattiaceae with the living ones is perfectly evi-
dent. Of these undoubted Alarattiaceae may be mentioned the
following genera : Ptychocarpus, Astcrothcca (Scott (t) Figs.
91, 92), Scolecoptcris and Danccitcs (Potonie, (3), Figs. y6,
79). The two former genera resemble in the form of the sori
(synangia) the living genus Katilfussia. .Danccitcs resembles
so closelv the jjenus Daucca that it mav verv well be considered
identical. All of the genera mentioned occur in the Carbonif-
erous rocks, but also are found in the early Mesozoic. The re-
cent genus Marattia has been found in the latter formations;
and of about the same age are Dancca-Yike forms which have

XVI FOSSIL ARCHEGONIATES 583

been described under the name Danccopsis. The other hving
genera are not known as fossils, although certain fossil genera
seem to be related to them. Thus Asterotheca and Scolecop-
teris have been placed in the Angiopteridese, PtycJwcarpus in
the Kaulfussieae.

Besides the forms which are unquestionably to be referred
to the Marattiales, there are a good many types of Palaeozoic
Ferns which show apparent resemblances to the true Maratti-
acese in the structure of the sporangium, but which have the
individual sporangium entirely distinct, instead of more or less
united w^ith its neighbours as in the typical synangium of most
Marattiacese. This free sporangium is structurally like that
of such forms as Angioptcris, in which the sporangia are nearly
separate, and not improbably represents a Marattiaceous type
in which this tendency is carried further than in any of the liv-
ing genera. In still other forms of supposed Marattiaceous
affinity, c. g., Uniatopteris (Potonie (3), Fig. 68), the spo-
rangia are borne upon sporophylls, which are completely cov-
ered w^ith them, as in the fertile fronds of Osmunda or Bo-
trychium. In all of the living Marattiaceae except Dancea, the
synangia are borne upon unmodified leaves. In Dancea, how-
ever, the segments of the sporophyll are much contracted, and
the large synangia almost completely cover the lower surface
of the pinnae, and in this respect it suggests an approach to'
those Palaeozoic types in which the lamina of the fertile leaves
is entirely wanting.

It is not unlikely that some of the Carboniferous Maratti-
ales were more or less synthetic types, connecting the typical
Marattiacece with the later developed Leptosporangiates. The
genus Senftenhergia (Potonie (3), Fig. 86), for example,
seems to resemble to a certain extent both Marattiaceae and
Schizaeaceae, while Renmiltia (Stnriella) has been compared
with both the Osmundaceae and Schizaeaceae.

The Marattiaceae seem to have maintained their ascendency
well into the Mesozoic. Raciborski (see Scott (i), p. 303)
found in upper Triassic beds about 70 per cent, of the Ferns to
be Marattiaceae ; but in lower Jurassic beds there was a remark-
able falling off in their number, only about 4 per cent, being
referable to the Marattiaceae. At the present time their num-
ber is less than one per cent, of the living species of Ferns.

While there is some evidence of the presence of leptospo-

S84 MOSSES AND FERNS chap.

rangiate Ferns during the Palaeozoic, none of these forms are
beyond dispute. That there were Ferns whose sporangia pos-
sessed a well-marked annulus seems certain, but the character
of these sporangia is somewhat doubtful. Of forms perhaps
allied to the Gleicheniaceoe, may be mentioned the genus Oligo-
carpia (Scott (i), Fig. 92). Sporangia have also been found
wnth a transverse annulus not unlike that of the Hymenophyl-
laceae, and described as Hymenophyllitcs, and not infrequently
sporangia are encountered which suggest the Osmundaceae, and
there is also evidence for the existence of forms allied to the
Schizaeaceae.

While the Marattiaceae were still predominant at the begin-
ning of the Mesozoic, by the time the Jurassic formations are
encountered, they are largely replaced by the lower leptospo-
rangiate Ferns. Osmundaceae and Cyatheaceae appear to have
been the predominant families at this period (Scott (i), p.
304). There were also Schizaeaceae, Gleicheniaceae, and per-
haps Hymenophyllaceae, but no true Polypodiaceae have been
found in the earlier Mesozoic formations.

A characteristic family of the Mesozoic is that of the Ma-
toniaceae, which combines characters of the Gleicheniaceae and
Cyatheaceae and was represented by very many forms. At
present only two species of Matonia survive, rare Ferns of the
Malayan region.

The Polypodiaceae first appear in the later secondary for-
mations, and from that time have formed the prevailing Fern
type.

The remains of the Hydropterides, the heterosporous
Ferns, are too meagre and uncertain to throw much light upon
their origin.

Cycadofilices (Scott (/), Potonie (j))

One of the most important results of the work of Palae-
botanists during the last decade has been the discovery that
many of the supposed Ferns of the Palaeozoic were really forms
which were intermediate between the true Ferns and Cycads,
and hence they have very appropriately been named Cycado-
filices. Some of the Cycadofilices were evidently nearer to tlie
Ferns than to the Cycads. Of these may be cited the genera
hyginodendron and Heteranginm, which have been very fully

XVI FOSSIL ARCHEGONIATES 585

studied by Scott ( i ) . These had Fern-hke foHage, and the
structure of the stem was also hke that of the Ferns, but there
was a marked secondary thickening of the stem, such as is rare
in Hving Ferns, but is known in the larger species of Botrychi-
imi. The structure of the stem in Lyginodcndron has been
compared to that of OsmiDida and the Gymnosperms (Scott,

/. c, p. 314).

Hctcrangium has a monostelic stem, which agrees closely
with that of Gleichenia, except for the secondary thickening.
Both Lyginodcndron and Hctcrangium had leaves like those of
a typical Fern. Unfortunately practically nothing is known
about their sporangia.

Of the more Cycad-like forms may be mentioned Cycado-
xylon and Mcdullosa. While the sporangia of these forms is
not certainly known, it is possible that they may have been het-
erosporous, or even seed-bearing. (For a full account of these
important forms, the reader is referred to Prof. Scott's work
(Chap. X, XI).

During the past few years there have been found associated
with the Fern-like leaves of the "Nciiroptcris" and "Alcthop-
tcris'' types, structures which appear to be real seeds, showing
that some, at least, of the Cycadofilices were seed-bearing
plants. For this reason it has been suggested that the name
Pteridospermeae be applied to the Cycadofilices (Grand
'Fury (I)).

The peculiar genus Nocggcrathia (Potonie (j), Fig. 158)
is one of the few spore-bearing fossils, which has been referred
to the Cycadofilices.

Equisetine.^ (Scott (i) ; Sczvard (i))

To this class are usually assigned two groups of fossil plants,
one belonging to the Equisetace^e, and represented by the genus
Eqiiisetitcs, which evidently was very close to the genus Eqni-
sctum, if not identical with it. The other group, the Calama-
riacese, differed in some respects from the living forms, and
there is much diversity of opinion about their real affinities.
The best known members of this order are the Calamitege,
whose anatomical structure is well known. Cormack (i) has
made a comparison of the structure of these with Equisctnm,
and comes to the conclusion that the type of structure is essen-

586 MOSSES AND FERNS chap.

tially the same. The general points of difference are the com-
pletely separate leaves of the Calamites, the frequent absence of
diaphragms at the nodes, and the marked secondary thickening
of the vascular bundles. Cormack has shown that a slight
thickening of the same character occurs in the nodes of Eqni-
setum maxiimun, and in the Calamites this thickening seems to
begin in the nodes and to extend later to the internodes. He
concludes that all the Calamites possessed this secondary thick-
ening of the stem. The two groups Annularieae and Aster-
ophylliteae, wiiich have slender stems with regular whorls of
leaves at the nodes, have been found to be to some extent, at
least the smaller branches, of indubitable Calamiteae; but it is
questionable whether this is always so.

The most important remains of this group are the fossils
known under the name CalaniostocJiys. These are cone-shaped
structures, whose close affinity with Equisctnm is beyond ques-
tion. The whorls of sporophylls, which are peltate, like those
of Eqnisctum, and bear four sporangia upon the lower surfaces,
are separated by alternating wdiorls of sterile leaves. Through
the kindness of Dr. D. H. Scott I have had an opportunity of
examining a beautiful series of sections of C. Binncyana. The
structure of the axis and sporangia correspond in the closest
manner to those of EquiscUun, but a most interesting difference
is the fact that this genus was heterosporous. Macrospo-
rangia and microsporangia occurred in the same strobilus, but
the difference in the size of the spores is much less than in the
living heterosporous Ferns and Lycopods.

The oldest known fossil belonging to the Equisetine?e is
Asterocalamitcs (Archcuocalamitcs), which has been made the
type of a special family Protocalamariacese. Asterocalamitcs
was structurally very much like Equisctnm, from which it dif-
fered, however, in the leaves, which were much better devel-
oped, and not united into a sheath. The leaves were repeat-
edly forked, and of considerable size (Scott ( i), Figs. 28, 29).
The cones are not certainly known, but a cone quite similar to
that of Equisctnm has been found which perhaps l>elongs to
Asterocalamitcs, and has been attributed to that genus.

The name Equisctitcs has been given to those fossil Equise-
tacCcT which closely resemble the living genus Equisctum. In
the Triassic and Jurassic were numerous arborescent Equise-
taceae which closely resembled the living genus Equisctum, but

XVI FOSSIL ARCHEGONIATES 587

showed a secondary growth in thickness which is almost en-
tirely wanting in all the living species. These great horse-
tails rapidly disappear from the later formations.

The genus Equisetites has also been reported from the later
Palaeozoic formations, but there seems some question whether
these are not more nearly allied to the Calamariacese.

Two other Mesozoic genera have been described, which
probably are allied to the Equisetacese, but they are too imper-
fectly known to make this at all certain. These are PJiyllo-
tJieca and Schizoncura. Both had the characteristic jointed
stems with the leaves more or less completely united into sheaths
about the nodes, as in Equisetum, but the leaves were better
developed than in that genus. (See Seward (i), Figs.
68, 69).

The oldest known member of the class, Aster ocalamites,
has been found in the middle Devonian. In the later Devonian
the true Calamites appear and increase rapidly in numbers dur-
the Carboniferous, disappearing before the Trias, when their
place is taken by forms closely allied to the living Equisetaceae.

Sphenophyllales

The Sphenophyllales comprise a small number of extremely
peculiar fossils, belonging mainly to the Palaeozoic, but extend-
ing- into the earlier Mesozoic also. Aside from the fructifica-
tions which have been attributed to them, and some of which
have been described under other generic names, they have all
been referred to a single genus, S phenophylhim. They w^ere
plants with slender, jointed stems, resembling more nearly
those of the Equisetaceae than any other living Pteridophyte.
About the nodes were whorls of wedge-shaped leaves, in some
cases dichotomously divided, and not unlike those of Archceo-
calamites. (Potonie (3), Figs; 172-75).

The anatomy of the stem is very different from that of the
true Equisetales, having a single central vascular cylinder, in
some respects like that of the typical Lycopods. It has been
compared to that of Psilotiim or Tmesipteris. (Scott (i),
T^igs. 34, 35).

The fructifications of undoubted species of Sphenophyllum
have been found, and the fossils described under the names
Botimianites and Cheirostrobus are supposed to have been the

588 MOSSES AND FERNS chap.

cones of Sphenophyllacese. These cones (Scott, (i), Figs. 33,
39-44) on the whole most nearly resemble those of the Cala-
mariacCcTe, having whorls of sterile bracts between the whorls
of sporangiophores. Prof. Scott, to whose researches is due
the account of the very peculiar CJieirostrobus, thinks that this
combines the characters of the Equisetinea^ and Lycopodineae,
and indeed looks upon the Sphenophyllales as a synthetic
group, intermediate between Equisetinere and Lycopodineae.

Potonie ((3), p. 204) considers that the Sphenophyllaceae
represents an off-shoot from the Protocalamariaceae, and are
in no way allied to the Lycopods.

According to Potonie (/. c, p. 182) it is probable that
Sphfuophylhim existed for the Silurian, but Seward ((i), p.
413) says that all of the fossil Sphenophylla of pre-Carbon-
iferous age, are of doubtful authenticity, although he thinks
they probably date from the Devonian.

Lycopodine^ {Potonie (s) ; Scott (i) ; Solms-Laubach (2))

Many fossils undoubtedly belonging to the Lycopodineae
are found in Palaeozoic formations, being especially abundant
in the Coal Measures, where many arlx)rescent types are con-
spicuous features of the flora. Of the* smaller fossil forms, it
seems pretty certain that several described under the generic
name Lycopodites are closely related to the living genus Lyco-
podhim. Like the living species, some of these fossil forms
are homophyllous, others heterophyllous. In many instances,
these fossil Lycopodiaceae have the strobili preserved, so that
there is no doubt of their real nature, although it cannot l^e cer-
tainly shown, whether they were homosporous or heterosporous,
and it therefore is doubtful in many cases whether they are
more nearly allied to Lycopodium or SclagincUa. It is quite
possible (Potonie (3), p. 259) that Ly-copoditcs Stockii, from
the lower Carboniferous, and L. elongatus, for example, may
be proj^erly referred to the genus Lycopodunn.

The arborescent Lycopods, belonging to the families Lepi-
dodendraceae and Sigillariaceae are among the most character-
istic of all fossils, and occur in great numbers, especially in the
Coal-measures.

The Lepidodendraceae were plants of large size, which must

XVI FOSSIL ARCHEGONIATES 589

have closely resembled, except for their much greater dimen-
sions, such species of Lyco podium as L. cernuum or L. den-
droideum. The branching was prevailingly dichotomous, and
the shoots thickly set with acicular leaves of a size correspond-
ing to the dimensions of the shoots. SigiUaria seems to have
been much less freely branched than Lcpidodciidron, and it
has even been supposed that in some species branching was en-
tirely suppressed. Of the living species of Lycopodiiim, L.
inundatum or L. sauriirus may be compared in habit to Sigil-
laria. Trunks of Lcpidodendron a hundred feet in length have
been found, showing the genuine tree-like proportions of these
giant Club-mosses.

The base of the stem in both Lcpidodendron and SigiUaria
is often found connected with forking structures, which were
originally described as distinct fossils under the name Stig-
viiavia. It is clear, however, that these were the underground
parts of Lepidodendron and SigiUaria, probably rhizomes
rather than true roots. The name Stigmaria is given them be-
cause of the very regular scars upon the surface, and these have
been shown to be the points of attachment for roots — or root-
lets, if the main Stigmaria branches are true roots and not rhi-
zomes (see Scott (1), Fig. 82). •

The slender pointed leaves were often of considerable
•length, 15 centimetres or more, and resembled those of Selagi-
ncUa rather than Lycopodiiim in having a ligule near the base.
(See Scott (i), Figs. 48, 58).

The internal structure is w^ell known in a good many forms,
especially among the Lepidodendracese (Scott (i)), and it is
evident that there was a good deal of difference among them,
especially in the degree of secondary thickening which occurred.

In all known species of Lcpidodendron (Scott (i), p. 123)
there is always a single stele with centripetally developed pri-
mary wood. There may or may not be a central pith. In the
larger stems there is usually a central medulla about which the
primary wood forms a ring. Probably the phloem, which is
rarely W'cll preserved, formed a ring outside the xylem. The
cortex is relatively very thick, as it is in the living Lycopo-
dinese, and through it passed obliquely the leaf-trace bundles,
one being given off from the central stele of the stem to each
leaf-base.

While in some species, c. ^., L. parvnlum, there w^as appar-

590 MOSSES AND FERNS chap.

ently no formation of secondary wood, in the majority of the
known species a zone of cambium arose outside the primary
wood, and from this were developed zones of secondary xylem
and phloem, precisely as in the Conifers and Dicotyledons.
The structure of the secondary wood, with the conspicuous
medullary rays, is strikingly like that of the wood of the Conif-
ers (Scott (i), Figs. 53, 56).

In addition to the secondary increase in thickness in the
stem due to the activity of the cambium, there was also a sec-
ondary thickening in the cortical region due to the formation
of a periderm, or cortical cambium. This mode of thickening
has been compared to that in Isoetes, and it also is not unlike
that in arborescent Monocotyledons, such as Dracccna and
Yucca.

In SigiUaria, whose stem structures are seldom well pre-
served, there was in most cases a ring of separate vascular
bundles and a large central pith, and in the former respect the
typical Sigillaria stem is even more like that of the Conifers
than is that of Lepidodendron.

In both Lepidodendron and Sigillaria the structure of the
leaves was more complicated than that of the living Lycopods,
and in certain respects they recall those of the Conifers (Scott
(i), pp. 148,. 204).

The sporophylls of the Lepidodendraceae were arranged in-
cones or strobili, closely resembling those of their living rela-
tions. (Scott (i), Figs. 47, 48, 65). The strobili have been
described under the name of Lepidosfrobns. The sporangia
were very much larger than those of any living Pteridophytes,
in Lepidosfrobns Brownii reaching a length of two centimetres.
In their large size and. sessile position, they suggest the spo-
rangium of Isoetes, with which they agree also, according to
Bower (15) in the development of partial trabecul^e. The
structure of the sporangia has In many cases been preserved
with wonderful perfection, and the spores themselves are often
encountered. In some species, e. g., L. Oldharnius, spores of
only one kind are known ; in others heterospory is very evident.
Whether the former type is really homosporous, or whether, as
yet, only microspores have been found, is not certain.

Another type of lycopodiaceous cone has been found and has
received the name Spenccritcs (Scott (i). Fig. 71). The spo-
rangia In Spencerites were short-stalked, and evidently not very

XVI FOSSIL ARCHEGONIATES 59i

different in form from those of Lycopodium. The spores are
very pecuHar in having a sort of wing, suggesting the append-
ages of the pollen-spores of Pinus.

It seems extremely probable that in some of the Palaeozoic
Lycopodine^ seeds were developed. The fossil seed described
as Cardiocarpon has been shown to be borne upon a cone which
is almost identical with Lepidostrobiis.

PSILOTACE^

Certain fossil remains have been classed with the Psilotaceae,
but there is much doubt as to the accuracy of these conclusions.
Solms-Laubach (2) says: 'The statements respecting fossil
remains of the family Psilotaceae are few and uncertain, nor is
this surprising in such simple and slightly differentiated forms.

If Psilotites does really belong to this group, a point which

I am unable to determine from the figures, we should be able
to follow the type as far down as the period of the Coal-
measures."

The genus Psilophyton, which has been found in the upper
Silurian, is regarded by Dawson as related to the Psilotaceae,
but there seems to be much question about the accuracy of his
conclusions.

CHAPTER XVII

SUMMARY AND CONCLUSIONS

The Interrelationships of the ArchegoniatcB

It is pretty generally conceded that the origin of the whole
archegoniate series is to be sought somewhere among the green
Algae, and that on the whole Coleoehccfe is, perhaps, the
form which is nearest to the simplest Muscine?e. While the
Characeae, as we have seen, approach the latter more nearly in
the structure of the sexual organs, yet the character of the vege-
tative parts is so different from that of any of the Muscineae, and
the sporophyte is so simple, that any close relationship of the
two groups is hardly probable. At best, the connection be-
between any known Alga and the Muscineae is a very remote
one.

From a study of the facts presented in the foregoing pages,
the conclusion has been reached that the Liverworts are not only
the most primitive of the existing Archegoniatae, but are also
the forms from which all the other groups have descended.
When, however, the question arises as to which of the existing
groups of Liverworts is the most primitive, the matter is not so
easy to settle. Thus while Riceia undoubtedly has the most
primitive sporophyte, the gametophyte shows a much higher
degree of differentiation than is found in most anacrogynous
Jungermanniaceae or in the Anthocerotes. The latter group,
while retaining an extremely simple type of gametophyte, has
the sporophyte developed beyond that of any other Liver^vorts.

It will be remembered that in the germination of most
thallnse Liverworts (and occasionally in the foliose forms as
well) the occurrence of a single two-sided apical cell is quite
general, although this may be absent from the fully-developed

592

XVI

FOSSIL ARCHEGONIATES 593

gametophyte. This suggests the possibihty of a derivation of
all of them from some type in which this two-sided apical cell
was permanent. Anenra and Metzgcria, among living genera,
have retained this condition, and in this respect are possibly
to be considered as representing the simplest type of the thallus.
The peculiar gemmae of the former, which may properly be
compared to the zoospores of Coleochate, strengthen this view.

The peculiar chromatophores of the Anthocerotaceae, as well
as the structure of the sporophyte, make it conceivable that they
have originated independently from forms lower than any exist-
ing Liverworts. It is quite possible, however, that the
Hepaticse and Anthocerotes represent two branches from a com-
mon stock, the multiple chromatophores of the true Hepaticae
being secondary, while Anthoceros has retained the primitive
single chromatophore, which has been replaced by the multiple
type in the other Archegoniates.

Starting from the primitive type, found in Anenra or Metz-
geria, we have endeavoured to show that development proceeded
along two lines — the Marchantiales and the Jungermanniales,
In the first one the differentiation consists mainly in the speciali-
sation of the tissues, while the gametophyte retains its strictly
thallose character; in the Jungermanniaceae it is rather in the
direction of the development of appendicular organs, while the
tissues remain nearly uniform. In both of these groups the
sporogophyte is comparatively simple, in strong contrast to
the Anthocerotes. The great preponderance of the foliose
Liverworts indicates that they are comparatively modern types,
which have adapted themselves to present conditions, and show
no indications of being connected directly with any higher

forms.

Whether the Anthocerotes are considered to have been
derived from the lower Hepaticae, or whether they have origi-
nated independently of these, the differences are too great to
consider the group merely an order of the Hepaticae, coordinate
with the Marchantiales or Jungermanniales. Aside from the
peculiarities of the gametophyte, especially the primitive type
of chromatophore, the structure of the sporophyte of all the
Anthocerotes is radically different from that of the true He-
paticae, and forbids a direct association with any of them.

Just as the simplest Jungermanniales may have served as
a starting-point for the two main lines of development in the
38

594 MOSSES AND FERNS chap.

Liverworts, so the Anthocerotes suggest the course of develop-
ment which resulted in two other lines, the Mosses and the
Pteridophytes. Whether the former class constitutes a con-
tinuous series, beginning with Sphagnum, or whether the
Sphagnaceae and the higher Mosses represent two branches
from a common stock, it seems extremely likely that the thalloid
protonema of Sphagnum is the primitive condition derived
from some Liverwort-like form similar to Anthoceros, and
that the alga-like protonema of the higher Mosses is a sec-
ondary development from it. The extensively branched proto-
nema is probably an adaptation associated with the rapid propa-
gation of the gametophyte, as the number of leafy shoots pro-
duced from such a protonema, is far greater than is possible
from a thallose protonema like that of Sphagnum.

In tracing the gradual evolution of the sporophyte among
the Muscineae we have seen how, starting with the simple spo-
rogonium of Riccia, which, physiologically, is only a spore-
fruit and quite incapable of independent growth, it gradually
becomes more and more independent by the development of a
special system of assimilative tissues, which reaches its extreme
in Anthoceros. It is true that the sporogonium always remains
to some extent parasitic upon the gametophyte, but this para-
sitism is very slight in Anthoceros, where the formation of a
root would make the sporogonium quite self-supporting. This
increase in the vegetative tissues of the sporophyte is at the
expense of the sporogenous tissue, which becomes more and
more subordinated to the assimilative and conductive tissue of
the sporogonium, as is seen in the Bryales among the Mosses,
and in Anthoceros.

In most of the Liverworts the sterile tissues of the sporo-
gonium are mainly concerned with the protection and dissemi-
nation of the spores. Only the foot, usually, can be properly
considered as an organ concerned in the nourishment of the
growing embryo. The seta, capsule wall, and elaters are
merely adaptations for facilitating the dispersal of the ripe
spores. In all of the Hepaticae, the whole of the central tissue
of the capsule constitutes the archesporium, all of whose cells
are devoted to the formation of spores or elaters. In the
Anthocerotes, however, the origin of the archesporium is quite
different, and it arises not from the central cells, but by a sec-
ondary division of the parietal ones. As yet there is no clear

XVII SUMMARY AND CONCLUSIONS 595

evidence of a direct connection with either of the series of the
Hepaticse, and it is probable that the Anthocerotes should form
a class coordinate with all the other Liverworts on the one hand,
and the Mosses on the other. It is possible that the axial bun-
dle of sterile cells found in the capsule of Pcliia and Anciira
may be homologous with the columella of the Anthocerotes,
and the latter therefore to be considered as derived directlv from
some simple form among the anacrogynous Jungermanniaceae ;
but as the sporogonium in all the Anthocerotes that have been
thoroughly investigated shows absolutely the same type of
structure, and in no case a secondary formation of the columella,
this is hardly probable. In the higher Anthocerotes, also, the
wall of the capsule, instead of simply serving for the protec-
tion of the spores, becomes a massive spongy green tissue com-
municating with the atmosphere by means of perfectly-
developed stomata of exactly the same type as those of the vas-
cular plants. This similarity in the assimilative system,
together wnth the basal growth of the sporophyte and the cen-
tral strand of conductive tissue, has of course suggested a rela-
tionship with the vascular plants. Indeed the sporogonium of
Anthoccros is much more like the spike of a small Ophioglos-
sum, for example, than it is like the sporogonium of Riccia.

The Mosses, like the foliose Liverworts, seem to represent,
a modern, extremely specialised type, with no direct connection
with higher forms. Probably related to the Anthocerotes
through Sphagnum, their further development has diverged
farther and farther away from the other Archegoniatse, until in
the Bryinese both gametophyte and sporophyte have little in
common with them. In both cases, an extreme specialisation
is attained which has no parallel among the Hepaticae; but
whether it is the highly developed leafy gametophoric shoot of
Polytrichum or Dawsonia, or the.equally complex sporogonium
of the same forms, the resulting structures are very different
from the corresponding ones in the vascular plants.

The complete emancipation of the sporophyte is first
attained in the Pteridophytes. The development of a true root
at once establishes the independence of the sporophyte, and
inaugurates a new era in the history of the Plant Kingdom, as
there is at last developed a plant type, essentially terrestrial in
its habit. Throughout the Pteridophytes it is the sporophyte,

596 MOSSES AND FERXS chap.

or neutral generation, which claims our principal attention,
and not the much reduced gametophyte.

The three classes of the Pteridophytes, while they differ
strongly in the form of the sporophyte, are yet so much alike
in the essential characters of the sexual generation, as to make
it inconceivahle that they can have originated from very widely
divergent ancestors. The more closely the gametophyte is
studied in all of them, the more evident hecomes the strong
resemblance to the Anthocerotes, whose sporogonium has
always been recognised as the nearest approach to the sporo-
phyte of the vascular Archegoniates. This is notably the case
when we consider the structure and development of the sexual
organs, which in the Anthocerotes differ so remarkably from
those of the other Muscine?e. Whether the submersion "of the
archegonia and antheridia in the thallus is the result of the cohe-
sion of an envelope, such as is formed about these in Sphccrocar-
piis or Riccia, it is impossible to say, but there is no trace of any
such process in the development of the sexual organs in any of
the investigated species.

The probable homology of the four-rowed neck of the arche-
gonium of the Pteridophytes with the cover cells only of the
Liverwort archegonium, has already been discussed at length
in a preceding chapter. It is quite possible that a similar cor-
respondence may exist between the antheridium in the lower
Pteridophytes and the Anthocerotes. It will be remembered
that in the latter the single antheridium, or group of antheridia,
arises from the inner of two cells formed from the division of a
superficial cell of the thallus, and that the inner cell may either
give rise to a single antheridium, or more commonly, by
repeated longitudinal divisions, a group of antheridial mother
cells is formed. The whole process is strikingly different from
the development of the superficial antheridia in the other groups
of Liverworts. In all of the homosporous Pteridophytes except
the leptosporangiate Ferns, however, the first division in the
antheridial cell is exactly as in the Anthocerotes ; but instead of
the inner cell developing into a distinct antheridium, the whole
of it is devoted to the formation of sperm cells. It seems not
improbable that this type of antheridium may have been derived
from one like that of the Anthocerotes by the suppression of
the parietal cells of the antheridium.

Aside from the forms without chlorophyll, which are prob-

XVII SUMMARY AND CONCLUSIONS 597

ably all secondary, the Pteridophytes show four types of gameto-
phyte. The first, represented by most homosporous Ferns, is
the familiar heart-shaped prothallium, which strongly recalls
the simpler anacrogynous Jungermanniaceae or Dendroceros;
the second is the lobed prothallium of EquiscHim, which resem-
bles most nearly among the Liverworts such forms as Antho-
ceros fiisifonnis, but has an analogy also in the lobed prothallia
sometimes met with in Osmiinda. In some species of Trich-
omancs and Schiz(Ta there occur the branched filamentous pro-
thallia, which some authors look upon as an indication of direct
relationship with forms intermediate between Algse and Musci-
neae. As other species of Trichomanes have the same type of
prothallium as the. other Ferns, and this is always true of the
closely related genus HyinenophyUnm, this view is open to
question. The green prothallium of Lycopodhun ccrmmm dif-
fers from the somewhat similar one of Equisehim, in the essen-
tial point that in the former we have to do with a radial
structure, in the latter with a dorsiventral one. The upright
gametophyte of Lycopodiiim, with its terminal circle of leaf-like
lobes, might be compared to a leafy Moss-shoot, although it is
hardly probable that this resemblance is more than superficial.

As far as the form and growth of the prothallium are con-
cerned, all forms except Lycopodium could be traced back to
the Anthocerotes ; the Fern type to forms like Dendroceros or
Anthoceros Iccvis, the Equisetnm type more resembling A. fiisi-
formis. The difference in the character of the chromatophores
is a very important one, and at present must forbid the assump-
tion of any immediate connection between the Anthocerotes
and existing Pteridophytes. Whether the occasional appear-
ance of very large plate-like chromatophores in the prothallium
of Osmiinda cinnamomea (Campbell (12)) is a reversion to a
primitive condition retained in the Anthocerotes, it is, of course,
impossible to say, but it is not" inconceivable, especially as the
same thing is found again normally in the sporophyte of Sel-
aginella. The regular doubling of the chromatophores in the
sporophyte of Anthoceros also suggests that the multiple chro-
matophores of most Archegoniates are secondary.

In the Anthocerotes the origin of the archesporium is differ-

^ent from that of the other Hepaticse, being hypodermal, as in

the lower Pteridophytes. The columella is in position similar

to the primary vascular bundles in the embryo of the Pterido-

598 MOSSES AND FERNS chap.

phytes, and in all probability is to be regarded as its homologue.
This central strand of conducting tissue, together with the
massive assimilative tissue system of the larger species of An-
thoceros, would make the sporogonium independent of the
gametophyte, were a root or some similar structure present by
which it could be connected with the earth. The alternation of
sporogenous and sterile cells in the archesporium, by which the
latter is divided into imperfect chambers containing the spores,
is, perhaps, the first indication of the separate sporangia of the
Pteridophytes. The most striking difference, then, between
the sporogonium of Anihoccros and the sporophyte of the sim-
pler Pteridophytes, such as Ophioglossum and Phylloglossiim,
aside from the absence of roots, which are, physiologically,
replaced by the massive foot, is the absence of a definite axis
with its lateral appendages (leaves) and sporangia. In Antho-
ceros the assimilative tissue forms a uniform layer over the
whole upper portion of the sporophyte, instead of being
restricted mainly to the special organs of assimilation or leaves,
and the archesporium is continuous instead of being divided
into definite sporangia. It has been claimed by Bower, how-
ever, that in Ophioglossum also there is originally a continuous
layer of sporogenous tissue, and the formation of the sporangia
is secondary.

Many attempts have been made to explain the origin of the
leafy axis of the sporophyte of the vascular Archegoniates from
the Bryophyte sporogonium. The latest theory is that of Pro-
fessor Bower (i6), who has brought forward much important
evidence to show that the simpler strobiloid Pteridophytes,
especially Phylloglossum, are the primitive forms from which
the others have sprung. His conclusions are based largely
upon a comparison of Phylloglossum with the embryonic con-
dition of Lycopodium, where the long dependence of the embryo
upon the prothallium, the rudimentary vascular bundles, and
the late appearance of the root are very striking, and certainly
indicate a very low rank for these forms in the pteridophytic
series. Another evidence of the close relation of the Lycopo-
dineae to the Bryophytes is the character of the spermatozoids,
which closely resemble those of the Liverworts, both in their
small size and the two cilia. Professor Bower's theory as to
the origin of the sporophytes is that these arose ''by a process
of eruption from a hitherto smooth surface." In this way

XVII SUMMARY AND CONCLUSIONS 599

he conceives that the smooth cyhndrical sporogonium became
transformed into a structure directly comparable to the strobilus
of Phylloglossitm. The sterile leaves, as well as the root, are
supposed to be outgrowths of the protocorm, which latter is
directly comparable to the massive foot in AntJwceros, whose
upper limit is the meristematic zone of cells at the base of the
capsule. Bower summarises his conclusions as follows : ''The
chief points which have been recognised thus far, and are be-
lieved to have been the important factors in advance, are : ( i )
sterilisation of potential sporogenous tissue; (2) formation of
septa; (3) relegation of the spore-producing cells to a super-
ficial position; and (4) eruption of outgrowths (sporangio-
phores) on wdiich the sporangia are supported."

Professor Bower's explanation of the origin of the Lyco-
podinese is certainly the most satisfactory that has yet been
given, and we may accept without much question his conclusion,
that Phylloglossitm is on the whole the simplest known Pterido-
phyte; but his further conclusion that the Ferns are also prob-
ably reducible to a strobiloid type is by no means convincing.

The conclusion reached by the author, after considerable
study of the subject, is that in the Ferns, and probably also the
Equisetineae, we have to deal with entirely distinct lines of
development. That is, while all three groups of the existing
Pteridophytes may perhaps be traced back to a common stock,
closely allied to the Anthocerotes, the three lines became differ-
entiated at a very early period, and the differences are so great
that it is difficult to see how any one of them could have been
derived directly from either of the others. In the Lycopo-
dineae and Equisetineae the axis is developed much more
strongly than the leaves, and the sporophylls are usually aggre-
gated into a more or less definite strobilus. The origin of the
strobilus in the Equisetinese may have been similar to that in
Lycop odium; but the sporangia themselves, as w'ell as the struc-
ture of the tissues and the prothallium, are more like those of
the Ferns, and make it extremely improbable that the strobilus
is homologous with that of the Lycopodineae. In the very defi-
nite apical growth of the stem and root, as w^ell as in the
structure and arrangement of the vascular bundles, Eqiiisetum
approaches much more nearly the condition found in Ophioglos-
sum than that of the Lycopodineae ; and the large multiciliate
spermatozoids, and the early divisions of the embryo, are also

6oo MOSSES AND FERNS chap.

suggestive of the Ferns rather than of the Lycopods. Of
course the fact that our knowledge of the Equisetineae is largely
based upon the single genus Equisctum, makes it unsafe to lay
too much stress upon conclusions drawn from a study of this
single type. However, such of the fossil forms as show unmis-
takable evidence of belonging to the Equisetinere, conform
closely in their structure, so far as it is known, to the living
types. The relatively large dichotomously branched leaves of
Archccocalamifcs, the oldest known member of the class, indi-
cate that the extremely reduced leaves of the later forms are
secondary. The form of the leaves in these ancient Equise-
tine^ is suggestive of filicinean rather than lycopodinean

affinity.

In the Filicinese the development of the leaves is usually
much greater than in either of the other classes, and the origin
of the sporophyll is probably different. Bowser considers the
sporophyll of Ophioglossnm, for example, as the homologue of
a single sporophyll of Lycopodinm, and the whole sporangial
spike as equivalent to a single sporangium. With this view the
author feels that he cannot agree, and it seems to him more
likely that the origin of the Eern-type of sporophyte w^as quite
different from that of the Lycopodinese, and that there is noth-
ing among the Eerns comparable to the strobilus of the latter.

If we could imagine the meristem at the base of the sporo-
gonium of Anthoceros to produce a lateral flattened appendage
or leaf, and the foot to develop into a root penetrating the
thallus into the earth, we should have a structure not very
unlike a small OpJiioglossum. In this case the sporangial spike
would represent, not a single sporangium of Phylloglossuiu,
but the whole strobilus, and the sterile segment of the leaf would
then be comparable rather to the sterile leaves (protophylls)
than to a single sporophyll. That the sporophyte in the Bryo-
phytes can develop a special assimilatory organ comparable to
a leaf, is seen in the apophysis of many Bryales. This is espe-
cially conspicuous in some species of Splachniim, where it might
almost be compared to a perfoliate leaf.

The recent discovery of the remarka1)le OpJiioglossum sim-
plex (Bower (20)) is especially important in this connection.
In this species there is no sterile segment to the leaf, and the
sporogenous spike must be considered a terminal structure. A
comparison of the younger stages of O. pendulum with O. sim-

XVII SUMMARY AND CONCLUSIONS 6or

plex, shows that in the former also it is not improbable that the
spike is really terminal, and the lamina of the leaf a lateral
appendage of it as it is assumed it must have been in the ances-
tral form.

While the Lycopodineae correspond closely to the Bryo-
phytes in the form of the spermatozoids, these in the other
Pteridophytes are large and multiciliate. Whether these pecul-
iarities have arisen independently in the Filicinese and Ecjuise-
tinese, or whether thev are inherited from some common ances-
tor, there is no means of deciding, but the latter view is prob-
ably the correct one, and it is likely that the two classes have
a common, but extremely remote origin. None of the
Muscinese, so far as is known, depart from the biciliate type, but
among Algae CEdogonhim offers a similar exception to the
usual biciliate form.

The Lycopodiacese and Selaginelleae constitute a sufficiently
direct series, but the exact affinity of the Psilotaceae to these is
by no means clear. Our complete ignorance of the sexual stage
of the latter, as well as their parasitic habit, makes it impossible
to judge just how far their simple structure is primary and how
much is due to reduction. More evidence also is required in
regard to their assumed affinity with the Sphenophyllaceae.

The reasons for regarding the eusporangiate Ferns as the
lowest of the Filicineae have already been given at length, but
may be summarised as follows: (i) The structure of the
gametophyte and sexual organs corresponds more nearly to that
of the Liverworts than do those of the Leptosporangiatae, and
the prothallium is larger and longer lived than in the latter; (2)
the embryo remains much longer dependent upon the gameto-
phyte, and the latter may live for a long time after the sporo-
phyte becomes independent; (3) the differentiation of the
organs and tissues of the embryo takes place later than in the
Leptosporangiates, and the tisslies of the mature sporophyte are
also simpler than in most of the latter ; (4) the sporangia of the
Eusporangiatae, especially Ophioglossum, are of a much less
specialised type than in the typical leptosporangiate Ferns, and
approximate more nearly the condition found in Anthoceros;
(5) the small number of species of the Eusporangiatae, but the
wide divergence of type shown, especially by the two groups of
the Ophioglossaceae and Marattiaceae, indicate that these are
remnants: of formerly more predominant forms. Finally, the

6o2 MOSSES AND FERNS ^ chap.

strong evidence of the geological record that the Eusporangiatse
were the prevailing types in the earlier formations, and have
been supplanted by the more specialised Leptosporangiatse in
more recent times, is reasonably conclusive.

Owing to the very small number of living Eusporangiat?e,
the relationships of these among themselves and to the Lepto-
sporangiatre are difficult to determine. From the frequent oc-
currence of dimorphic leaves among the older fossil types of
Ferns, as well as on grounds of comparative morphology, the
type of leaf in the Ophioglossace?e is probably to be considered a
more primitive one than that of the living Marattiace?e. Of
the existing genera of Marattiace?e, Dancca is the only one in
which the sporophylls differ in form from the sterile leaves,
and this dimorphism probably indicates that on the whole it is
the most primitive of the living genera. Whether the extreme
type of synangium found in Dancca is older than the nearly free
sporangia such as those of Angiopteris, has been questioned, as
both types are found among the Palaeozoic Marattiacese ; but
the greater specialisation shown in the latter type indicates that
it is of more recent origin. There is a possibility that the two
types represent two lines of development originating from dif-
ferent stocks comparable to Ophioglossum and Hclmintho-
stachys among the Ophioglossaceae. The occurrence of Ferns
of unmistakable Marattiaceous affinity, but wnth fertile leaf
segments completely covered with free sporangia like those of
Botrychium or Osninnda supports this view.

While in such species of Botrychium as B. Viginianum,
there is a strong resemblance in the tissues to the lower lepto-
sporangiate Ferns, it is not so marked, on the whole, as those
in the Marattiace?e, which probably are nearer the Leptosporan-
giat?e, and probably have given rise directly to them.

The homosporous Leptosporangiatae or Filices constitute a
very natural order. The Osmundaceae are without much ques-
tion the most primitive members of the order, this being indi-
cated both in the gametophyte and sporophyte. While they
show certain points of resemblance to Hclminthostachys and
BotrycJiiiuii, their affinities seem to be rather with the Marat-
tiaceae, and presumably they have arisen from some Palaeozoic
Marattiaceae with free sporangia borne upon special leaf seg-
ments. It is not impossible that two others of the lower fami«
lies the Schizaeaceae and Gleicheniaceae, may have originated

XVII SUMMARY AND CONCLUSIONS 603

separately from forms like the Marattiaceae, and not from the
Osmundaceae as is usually assumed, although there is evidence
of a not remote relationship with the latter.

The affinities of the Gleicheniacese Cyatheacese and Polypo-
diaceae are very apparent. The Hymenophyllaceae, while prob-
ably of pretty ancient origin, form an aberrant group which
has become a good deal changed on account of its peculiar habit
of life. The Polypodiaceae are par excellence the modern Fern
type.

The two heterosporous families, the Marsiliacese and Sal-
viniacese, are independent developments. The former are prob-
ably allied to the Schizaeaceae, the latter to Cyatheaceae or
Hymenophyllaceae.

The development of heterospory in the different groups of
the Pteridophytes is of especial interest, from its bearing upon
the question of the origin of the Spermatophytes. That hetero-
spory arose in a number of widely remote groups is unques-
tionable. While among the living Pteridophytes it is confined
to the Ferns and Lycopods, the very perfect fossil remains of
Calamostachys show that heterospory was also developed' in
the Equisetineae, although apparently the difference between
the two sorts of spores was less marked than obtains in the other
two classes. In the leptosporangiate families, the Marsiliaceae
and Salviniaceae, although there is great reduction in the size of
the prothallium, its development is essentially the same as in
their homosporous relatives, and the female prothallium, if
unfertilised, usually develops chlorophyll, and is capable of
independent growth ; but in the Isoetaceae and Selaginellaceae
the formation of the female prothallium is much more like that
in the Spermatophytes, and makes it extremely likely that from
some such forms the latter have been derived.

The microsporangia of the Spermatophytes do not differ
essentially from those of the heterosporous Pteridophytes, and
the microspores (pollen spores) are shed before germination.
The macrospore (embryo-sac), however, is retained within the
macrosporangium (ovule), w^here it remains during the whole
period of germination. Among the Pteridophytes Selaginella
approaches this condition, as the macrospore is retained within
the sporangium until germination is far advanced. The
integument of the ovule is, with very little question, homologous
with the indusium. The young macrosporangium of A::olla is

6o4 MOSSES AND FERNS chap.:

extraordinarily like a developing ovule, and the closely invest-
ing indusium has all the appearance of an ovular integument.
The velum of Isoetes is possibly of the same nature.

The development of heterospory in several unrelated groups
of Pteridophytes at once suggests the possibility of a multiple
origin for the Spermatophytes. The radical differences be-
tween Gymnosperms and Angiosperms, and the absence of any
truly intermediate forms, make it extremely probable that these
two great divisions have originated independently of one
another, probably from different stocks, and it is by no means
unlikely that the same may be said of the Cycads, Conifers, and
Gnetace?e.

The discovery of motile spermatozoids in Cycads and
Ginkgo (Ikeno (i, 2) ; Hirase (i) ; Webber (i)), and the re-
cent studies upon Palaeozoic seed-l)earing plants all make it cer-
tain that the seed-habit has developed quite independently in
several w^idely separated groups.

Except for their siphonogamic fertilisation, the Gymno-
sperms really are much nearer the Pteridophytes than they are
to the Angiosperms. As both the pollen tube and the seed-
formation are but further developments of heterospory, it is
quite conceivable that these might have arisen independently
more than once. The close resemblance between the Conifers
and the Lycopods, especially SclagincUa, probably points to a
real relationship. The strobiloid arrangement of the sporo-
phylls, as well as the development of the prothallium and
embryo, are extraordinarily similar, and it is not unreasonable
to suppose that this is something more than accidental. The
strong resemblance between the method of the secondary thick-
ening of the stem in the arborescent fossil Lycopodine?e, and
that of the Conifers, as well as the anatomy of the leaves sug-
gests a real affinity. It is known that some of these bore seeds,
which in structure and position may very well be compared to
those of typical Conifers. The prevailingly dichotomous
branching of Lepidodcndron, however, is very different from
the type of branching in the typical Conifers.

Recent studies on the Cycadofilices, and the discovery of
spermatozoids in the living Cycads, proves beyond a doubt the
origin of the latter from Fern-like ancestors.

The most recent evidence seems to support the old view that
Isoetes belongs in the series of the Lycopodineae ; nevertheless

XVII SUMMARY AND CONCLUSIONS 605

the gametophyte and embryo show characters that are more
Hke those of the Ferns, and the exact position in the system
of Isoetes must still remain somewhat doubtful.

The Angiosperms are in all probability all members of a
common developmental series, but just what is their relation to
one another and to the other vascular plants is not so evident.
It is usually held that they have been derived from the Gymno-
sperms through the Gnetacese, but it has also been suggested
that one or both of the divisions may have originated directly
from the Pteridophytes. Attention has been called more than
once to the close resemblance between the embryos of the Fili-
cineae and those of typical Monocotyledons, and this is especially
the case in Isoctcs, where, in addition, the. structure of the
mature sporophyte is much like that of the Monocotyledons.
It is possible that the surrounding of the sporangium by the
base of the sporophyll may be the first indication of the ovary
of the Angiosperms, but as this applies to the microsporangia
as well, much stress cannot be laid upon it. It is quite as easy
to trace back the embryo-sac of the Angiosperms to the macro-
spore of Isoetes as to the embryo-sac of the Gymnosperms ; and
when the great similarity between the sporophyte of the former
and the Monocotyledons is considered, the probability of the
origin of the latter from aquatic or semi-aquatic ancestors
resembling Isoetes is certainly considerable.

The essential similarity in the structure of the embryo-sac
in all Angiosperms yet examined, as well as the structure of the
flower, makes it almost inconceivable that the two branches,
Monocotvledons and Dicotvledons, could have arisen from dif-
ferent stocks. Strasburger's suggestion that the Dicotyledons
were derived directly from the Gymnosperms, and that the
Monocotyledons are a reduced branch of the former, is open
to objections both on morphological and palseontological
grounds, and we believe that the evidence we have at present
points to the Monocotyledons as the more primitive of the two
divisions of the Angiosperms, from which later the Dicotyle-
dons branched off. It is true that the researches of the past ten
years (Coulter (4)) show that there is less tmiformity in the
structure of the embryo-sac than was supposed to be the case;
but there is no question as to the essential similarity in struc-
ture in all Angiosperms. It is also becoming evident that the
dicotyledonous habit may have developed more than once.

6o6

MOSSES AND FERNS^

CHAP.

To summarise briefly: the conclusion reached is that the
Spermatophytes represent not one single line of development,
but at least two, and perhaps more, entirely independent ones,
having their origin from widely separated stocks. The Gymno-
sperms (at least the Conifers) are probably direct descendants
of some group of Lycopods allied to the Selaginellaceae, or
Lepidodendraceae, while the origin of the Cyads and Angio-
sperms is to be looked for among the eusporangiate Filicinese.

A ngiosperma

Coniferce

^arsih'acea^

Rrya}

Sphaznales

Salviniacece

Hepaticce

APPENDIX

CHAPTER II

P. g. The occurrence of gemmae of endogenous origin has also
been observed in other species of Aneura, and the multicellular gemmae
of Metzgeria have been found to originate also in much the same
manner. (Goebel (8), Cavers (9), Evans (3).) Recently Buch (i)
has described unicellular gemmae of endogenous origin in a leafy
liverwort, Haplozia ccespitica.

P. 10. A recent study of Sphagnum (Bryan (i) ) shows that in
this Moss the apical growth of the archegonium is very limited.
The terminal cell (cap cell), early undergoes a vertical division, and
no basal segments are cut off from it. In a number of Liverworts, on
the other hand, there is a Umited apical growth (Campbell (37, 39) )j
although none of the canal cells arise from the terminal cell. It is
thus clear that the differences between the archegonium in the
Liverworts and Mosses are less marked than has hitherto been sup-
posed.

'P. 12. The origin of the sexual organs of the Archegoniates is
very obscure. In some respects they resemble most nearly those of
the Characeae, but it is doubtful whether these resemblances indicate
any real relationship.

Perhaps the most plausible explanation of the origin of these
organs from those of the Algae is that of B. M. Davis (3), who thinks
that they most nearly resemble the plurilocular ''gametangia " of
certain Brown Algae. He does not think that there is any genetic
connection between the latter and tlie Archegoniates, but rather that
the connection is to be sought with some Green Algae which had
gametangia similar to those of the Phaeophyceae. There are still in
existence species of Schizomeris and Draparnaldia which show an
approach to these structures, but presumably the direct a-ncestors of
the Archegoniates are no longer in existence.

Davis thinks that the outer cells of the gametangium through
steriUzation became the wall of the antheridium or archegonium,

607

6o8 MOSSES AND FERNS

while each cell of the inner tissue gave rise to a gamete. In the
archegonium the fertile tissue formed a single axial row, only one
cell of which, the egg, normally was functional.

Schenck (i) has come to much the same conclusion as Davis, but
believes the Archegoniates have come directly from Brown Algae —
marine Phceophyceae.

In view of the many other obvious points of resemblance between
the Archegoniates and the fresh-water Green Algae it is highly im-
probable that there should be any genetic connection between them
and the strictly marine Phaeophyceae.

It has been argued by Goebel among other writers, that the arch-
egonium and antheridium of the Archegoniates are essentially
homologous organs, which would of course agree with the theory of
their derivation from some type of plurilocular gametangium. This
view is strengthened by work of Holferty (i) and others, who have
shown that in certain Mosses structures combining the characters of
archegonium and antheridium may occur.

P. 13. There may be some question as to the desirability of
removing the Anthocerotaceae from the Hepaticae. Thus Cavers
(9), who has made a very careful study of the inter-relationships of
the Bryophytes, believes that the differences between the Antho-
cerotaceae and the other Liverworts are not sufficient to warrant the
establishment of a separate class, but thinks that they merely represent
an order of Hepaticae, Anthocerotales, coordinate with the Marchan-
tiales and Jungermanniales.

P. 17. The development of the spermatozoid of the Hepaticae
has been the subject of numerous investigations during the past ten
years and while there is general agreement as to certain points,
there is a decided difference in others.

In all cases that have been recently examined, the final division of
the spermatogenous cells results in the formation of a pair of "sperma-
tocytes, " or sperm-cells, which may be separated by a deHcate division
wall, e.g. Pallavicinia, Calycidaria — or the division wall may be
suppressed, as in Marchantia and Fossoinhronia.

All authorities agree that after the final division into the sperma-
tocytes, there is always present a small body, the "blcpharoplast,"
but as to the nature of this body, the statements are not at all in
accord.

Ikeno (4), who studied the spermatogenesis especially in Marchantia
polymorpha, beheves that the blepharoplast is a centrosome, and that
it is of nuclear origin. Schaffner (i) supports this view, but other

APPENDIX 609

writers {e.g., Woodburn, Escoyez) deny the presence of centrosomes
and consider the blepharoplast to be an organ of cytoplasmic origin.
Ikeno also describes a peculiar body to which he gives the name
''Nebenkorper, " whose nature is problematical.

Humphrey (i) has studied the spermatogenesis of Fossomhronia,
where he decided that the bl«"Dharoplast arose de novo in the cyto-
plasm. In Fossombroma the hn. ■• division of the sperm-cells is
diagonal, as it is in Marchantia, and the spermatids appear triangular
in shape. In Fossombroma there is a structure suggestive of the
''Nebenkorper," but Humphrey states that in this case it forms part
of the spermatozoid. In other Hepaticae, e.g., Calycularia, Pellia,
the spermatids are nearly hemispherical.

In a recent paper, Wilson (2) states that he believes the blepharo-
plast in Pellia to be derived from a centrosome, and he also describes a
globular body " limosphere," and an '^ accessory body," as present
in the spermatid, but was not able to determine their origin.

All agree that the cilia arise from the blepharoplast, which very
early assumes a position at the periphery of the spermatid. Most
authors state that the elongated thread which connects the cilia with
the nuclear portion of the spermatozoid is formed by the elongation
of the blepharoplast itself ; but Wilson thinks that the greater part
of the thread does not belong properly to the blepharoplast.

The bulk of the body of the spermatozoid is undoubtedly lomied
from the nucleus of the spermatid which becomes homogeneous in
appearance and elongates to form a more or less coiled body.

P. 20. In his resume of the inter-relationships of the Bryophytes,
Cavers (9) proposes the establishment of a third order of Hepaticae
(exclusive of Anthocerotales), the Sphaerocarpales, which is to a cer-
tain extent intermediate in character between the Marchantiales and
the Jungermanniales. Spharocarpus (see Chap. Ill) is on the whole
the simplest known Liverwort, and Cavers' view is that the family
Sph^rocarpaceae is sufficiently different from the other two orders to
warrant the establishment of a third order, Sphaerocarpales, which is
more primitive than the other two.

P. 21. It has been proposed to recognize two other families
intermediate between the Corsiniaceae and the Marchantiaceae, viz.
the Targioniaceae, comprising Targionia and Cyathodium, and the
Monocleacese with the single genus Monoclea. The differences be-
tween these genera and the typical Marchantiaceae are probably sufh-
cient to warrant the establishment of these families. (See Cavers

(9).)

6 10 MOSSES AND FERNS

P. 23. Recent studies on Targionia (Deutsch (i) ), (O'Keefe (i) )
have shown the presence of a single apical cell, and it is by no means
unlikely that this will prove to be the case generally in the Marchan-
tiales.

P. 25. Barnes (2), after an examination of a number of Marchan-
tiales, states that invariably the formation of the air-chambers
begins by the separation of the cells below the superficial layer, and
thus the pits between the latter are secondary, being formed by a
splitting of the cell-wall. He examined only Riccia natans and R.
fluitans, neither of which conforms to the type found in most ter-
restrial species. The papers by Miss Hirsch (i) and Miss O'Keefe
(i) show that Leitgeb's account of the formation of the air spaces in
Riccia glauca, and other allied species, is entirely correct.

P. 32. The spermatogenesis in Riccia Frostii has been studied
in detail by Miss Black (i). It corresponds closely with that of other
Marchantiaceae. The final division of the sperm-cells is a diagonal
one without the formation of a division wall, and results in a pair of
triangular spermatids. There is no evident connection between
blepharoplast and a polar granule that might be considered to be a
centrosome. Eight chromosomes were noted in the sperm-nucleus.

P. 35. Beer (i) has made a critical study of the spore division in
Riccia glauca. His results agree entirely with the writer's studies in
this species, and in 7^. tricJiocarpa, so far as the details were examined.
In both of these species, the spore mother cells, previous to the final
division into the spores, completely fill the cavity of the sporogonium.
The walls between them are very delicate, but are readily demonstrable
by Bismarck-brown. The protoplasts are usually more or less con-
tracted in microtome sections, and where the division walls are not
stained, look as if they were completely isolated, but probably in
most cases the contraction is due in part to the efi"ect of reagents.

Beer states that the division walls do not show the cellulose
reaction. Sooner or later these walls become disintegrated and the
nearly globular protoplasts, which have developed new membranes,
become entirely isolated. No evidence of any intercellular nutritive
substance, such as Garber (i) and Lewis (i) describe in R. natanSj
can be demonstrated for either R. glauca or R. trichocarpa.

The nucleus of the spore mother cell contains a conspicuous deeply
staining body (see text, Figs. 6, 7), which Beer states is a nucleolus;
but from his description and figures of the early stages of mitosis it
looks as if this might be really composed of the closely united chromo-
somes. The latter, according to Beer, are probably seven or eight in

APPENDIX 6ii

R. glauca, while Garber and Lewis give but four chromosomes in the
spores of R. natans.

The primary division walls separating the young spores, according
to Beer, are a pectose-cellulose compound, while the secondary thicken-
ing of the walls shows the presence of callose.

The spore coat is composed of three parts, an outer coat which very
early shows cutinization ; a middle coat, also more or less cutinized,
and itself showing a differentiation into three laminae ; and finally the
inner coat, or endospore, which arises late in the development of the
spore, and which shows pectose and cellulose reactions.

Beer thinks that the materials necessary for the development of
the spore membranes is derived mainly from the disintegration of the
outer sterile cells of the sporophyte, and the inner cells of the calyptra,
but that there is probably a certain amount of nutritive matter
transferred from the vegetative tissues of the gametophyte.

P. 39. The more recent studies of Ricciocarpus (see Cavers (9) )
indicate that this genus should be united with Riccia, as was originally
done.

P. 40. Tesselina has recently been discovered in the Southern
United States (Howe (6) ).

P. 41. Corsinia marchantioides occurs in the south of Europe and
in the Canary Islands and Madeira. Stephani (i) states that it has
also been reported from Louisiana. Boschia Weddellii is known only
from Brazil.

P. 42. Barnes and Land (2) have made an extended study of the
origin of the air-chambers in the Marchantiales, and conclude that
in all cases these begin by the formation of an intercellular space just
beneath the epidermis, and that the superficial pores, or stomata,
are formed secondarily by the subsequent extending of the inter-
cellular space to the surface. From Deutsch's study of Targionia,
however (Deutsch (i) ), as well as from the writer's studies on Fim-
briaria, it appears that sometimes, at any rate, as in Riccia, the first
evidence of the air-chamber is a pit between the epidermal cells,
which later extends to the underlying tissue.

There are two well-marked types of air-chambers. In Fimhriaria
Calif ornica, for example (see Fig. 14), through the rapid enlargement
of the thallus, the air-chambers become very large and irregular in
form, and there is not a sharp distinction between this lacunar tissue
of the dorsal region and the solid tissue of the ventral region.

In the second type, which is seen in Targionia and Marchantia, as
well as in most other Marchantiaceae, the lacunar tissue consists of a

6i2 MOSSES AND FERNS

single tier of well-defined chambers, each opening at the surface by a
pore. In most of these (see Fig. i8') the green tissue consists for the
most part of short filaments growing from the floor of the air-chamber.
The free ends of these filaments, especially immediately under the
pore, are often colorless, and more or less enlarged. This is especially
conspicuous in Fegaklla (Cavers (6, 9) ).

The epidermal cells surrounding the pores keep pace with the growth
of the thallus, so that the pores remain of nearly their original size.

P. 49. Ernst (2) has more recently described the structure of the
thallus in Diimortiera trichocephala, collected in Java, and also of a
second species, D. vcliUina, in which the remains of the dorsal
lacunae are conspicuous. Wiesnerella is a genus evidently related to
Diimortiera, but having a well-developed epidermis with pores opening
into the air-chambers.

P. 56. Cavers has made a careful comparative study of the carpo-
cephalum in several genera of the Marchantiaceae and concludes that
in all of them, except Clevea and Plagiochasma, the carpocephalum is
of the composite type. He believes, however, that the Astroporae of
Leitgeb represent a natural group, and to a lesser extent this is true
of the Operculatae, although the limits between the latter and the
Compositae are not at all definite.

P. 58. Cryptomitriiim also occurs in the Himalayas.

P. 60. In a recent paper by Miss O'Keefe (i), the young embryo
Targionia is described as having two transverse divisions before any
longitudinal ones were formed — i.e., there was not the quadrant forma-
tion typical of the Marchantiales. The writer's preparations of the
young embryos showed the normal quadrant division (see Fig. 23),
and it would be interesting to know whether Miss O'Keefe's specimens
were abnormal, or whether possibly they were specifically different
from the California plant. Meyer (4) shows that in Plagiochasma
the young embryo consists of a row of four cells.

P. 65. In Diimortiera trichocephala, and in the allied genus Wies-
nerella, there is a very evident seta, and in Monoclea it is very much
elongated.

P. 69. Cyathodium is represented by several species in the warmer
parts of the world. The largest and least reduced species is C.
fcetidissimum, widely distributed through the Malayan region, where it
occurs sometimes in great abundance in shallow caves, or on deeply
shaded rocks. The delicate thallus appears to glow with a green
phosphorescence when seen at a certain angle, this being apparently
due to the form of the superficial cells, which reflect the light strongly.

APPENDIX 613

This species receives its specific name from its peculiar strong odor
when handled.

The archegonia occupy the same position as in Targionia, but the
envelope about the sporogonium is much less developed than in the
latter.

The antheridia are formed on very short ventral branches, on the
same plants that bear archegonia.

Lang (6) has made a careful study of this species as well as of a
second one which he refers provisionally to C. cavernarum.

The thallus consists mainly of a single layer of larger air-chambers,
bounded below by a single layer of cells, and opening above by well-
defined pores like those of Targionia, but there is no trace of the green
assimilating filaments found in the latter. In C. Ja^tidissimtim there
are several layers of ventral cells in the region of the midrib. The
cells of the superficial layer contain a few relatively large chromato-
phores, and this is the principal photo-synthetic tissue.

The archegonia and antheridia closely resemble those of Targionia.
As already surmised (see text, p. 70), Leitgeb's suggestion that the
antheridium is a single cell has proved incorrect. The early stages
of the embryo, as shown by Lang's investigations, resemble the Junger-
manniales rather than the Marchantiales. The first two divisions
are transverse (as Miss O'Keefe found in Targionia), and the lower-
most cells form a sort of haustorium, instead of the massive globular
foot found in Targionia. There is a slender but short seta, as in
SphcBrocarpus, and except for the presence of a small thickened disc
at the summit, the sporogonium more nearly resembles that of Sphccro-
carpus than it does Targionia. The wall cells, however, develop
thickenings like those found in Targionia, and true elaters are
present.

P. 70. Occasionally receptacles have been found which bear
both archegonia and antheridia (see Ernst (i). Cutting (i) ).

P. 70. Stephani (i) records 200 species of Marchantiaceae, and
since his summary was published ajiumber of new species have been
described, including several new genera. The Himalayan region is
especially rich in these new types (see Kashyap (2) ).

P. 70. Schiffner, in a recent paper (4), still asserts that Monodea
should be referred to the Jungermanniales ; but the arguments he
offers are not very convincing. It may be said, however, in view
of the recent work on the Targionia ceae and Pellia (Hutchinson (i) ),
that there is a possibility that Monodea may be in a sense intermediate
between the thallose Jungermanniales of the Pellia type, and the

6i4 MOSSES AND FERNS

Targioniaceae. The characteristic lobing of the spore mother cells,
found in the Jungermanniales, is conspicuous in Monoclea, but occurs
also in Targionia, though not so markedly. The long seta of the
sporophyte can be explained by the semi-aquatic habit of Monoclea

(see Cavers (9) ).

P. 71. Goebel (27) has recently described a very remarkable
Marchantiaceous type, Monosclcnium, which shows some striking
indications of reduction, comparable to those in Monoclea and Dumor-
tiera. Like these, there is a complete disappearance of the air-chamber,
but evidences of reduction are also showTi in the reproductive parts.
The sexual organs are similar to those of the higher Marchantiaceae,
and are borne on special receptacles of the same txpe ; but the sporo-
phyte is much simpler, approaching in structure that of Corsinia or
Boschia. The sterile cells may show the character of true elaters,
or they may be undifferentiated nutritive cells like those of Sphccro-

carpus. '

P. 71. Cavers (6) thinks that Leitgeb's division of the Marchan-
tiaceae into the three groups, Astroporae, Operculatae and Compositae,
is to some extent a natural one. The sporogonium wall in the first
and third groups shows (usually) fibrous thickenings of the cell-wall,
these thickenings being absent in the Operculatae. The apical cap,
or lid, found in the Operculatae, does not, however, seem to be essen-
tiallv diffen'nt from the similar apical cap which is formed in many
of the Compositae, e.g. Wiesfterella, Marchantia.

CHAPTER III

P. 73. Recent investigations have showTi that the differences
between the antheridia of the Marchantiales and Jungermanniales
are less marked than has been assumed. Thus in Fossombronia
(Humphrey (i) ), the early divisions in the anthcridium resemble
those of the Marchantiales, and in Pellia (Hutchinson (i) ) this is
also sometimes the case, although usually the divisions follow those
of the t\T)ical Jungermanniales.

P. 75. The classification of the Jungermanniales is still far from
satisfactory. Cavers (9) has proposed to remove the ''Anelatereae"
from their association with the other Anacrogynae, and to establish a
distinct order, Sphaerocarpales, intermediate between the Junger-
manniales and the IVIarchantiales ; and there is a good deal to be said
for this suggestion.

APPENDIX 615

P. 75. As to the Elatereas, there is great difficulty in dividing these
into distinct famiUes. Cavers recognizes four famiUes, viz., Aneu-
raceae (= Metzgerieae), Blyttiaceaj (= Leptothecea?), Codoniaceae,
and Calobryaceae ( = Haplomitrea?). Of these the first two are almost
inextricably interrelated, and it will probably be best to combine
them into a single family. The family Codoniaceae contains a number
of genera which are very doubtfully related, e.g.,Pellia, Fossojnhronia,
and it will probably be necessary to remove some of the members now
included in the family, and perhaps to establish a new one.

The Calobryaceae, comprising the genera Calohryum and Haplo-
mitrium, is a very natural one, but its relation to the other Jungerman-
niales is somewhat problematical.

Stephani (i) states that he examined the original material of
Thallocarpus, and found it to be a Riccia. See also McAllister (i).

P. 75. A recent revision of the genus Sphccrocarpus (Haynes (i) ),
shows that S. terrestris does not occur in the United States. The
plant from the Atlantic states hitherto regarded as this species is
apparently identical with S. Texanus, which in turn is not distin-
guishable from S. Californicus, which is united with that species. A
third species, S. hians, has been discovered in Washington. See
also Douin (i).

P. 86. Evans (3) has shown that in Metzgeria the gemmae arise in
essentially the same way as in Aneura, but the gemma remains
attached to the thallus until it has formed a multicellular body of
considerable size.

P. 88. The genus Aneura, which is the largest among the An-
acrogynae, shows a good deal of variation in the form of shoot. Some
of the species, e.g., A. maxima, have a quite undifferentiated thallus
rivalling in size the larger Marchantiales. Other species show a more
or less definite midrib, and still others, e.g., A. Tjibodensis, have much-
branched upright shoots arising from a prostrate rhizome, as in
Hymenophyton (Umbraculum) ; but the branching is monopodial
instead of dichotomous.

P. 88. In Pallavicinia the central portion of the midrib is
occupied by elongated fibre-like cells with markedly thickened cell
walls.

P. 89. The antheridia in Pallavicinia (Mittenia) Zollingeri are
borne on the midrib, each one being covered by a scale. In other
species, e.g., P. radiculosa, P. Levieri, they are in a row on either side
of the midrib, and are covered by a shelf -Hke outgrowth, which is
more or less continuous. (Campbell and Williams (37).) Calycularia

6i6 MOSSES AND FERNS

and Podomitrium (Campbell (34, 39) ) closely resemble Pallavicinia
Zollingeri in the arrangement of the antheridia ; but in Podomitrium
they occur on special ventral branches. In Makinoa the antheridia
are in chambers, very much as in Aneura. (Miyake (2).)

P. 94. The archegonium of Fossomhronia (Humphrey (i) ) some-
times regularly shows six neck canal cells. In Pallavicinia radiculosa
the writer found usually five or six, and in Calycidaria radiculosa and
Podomitrium Malaccense the number is a])out the same, but may
probably in some cases be eight. Eight neck canal cells were also
found in Treubia, although Griin states that he found sixteen in the
full-grown archegonium. (Griin (i), Campbell (40).)

In Pallavicinia radiculosa the cap cell of the young archegonium
sometimes has several lateral segments cut off before the final quadrant
division occurs. There may be thus a limited apical growth of the
archegonium, somewhat as in the true Mosses, but such growth is
confined entirely to the outer cells. Podomitrium Malaccense may
show the same phenomenon. (See Gayet (i).)

The archegonial receptacle in most Anacrog^Tiae, e.g.^ Pallavicinia,
Calycularia, Podomitrium, is surrounded by an involucre composed of
several usually laciniated scales. Sometimes, however, as in Sym-
phyogyna and Makinoa, the archegonial group is subtended by a
single scale.

Within the involucre there may be developed a second envelope,
the perianth (see Fig. 41, A. per.), which forms a tubular sheath
often very conspicuous. The perianth does not form until after
fertihsation. It arises as a ring-shaped ridge about the group of
archegonia, and elongates rapidly with the growth of the young sporo-
phyte which it encloses. The perianth has evidently been developed
quite independently in a number of genera, while it is wanting in
others.

P. 94. Aneura has been the subject of several embryological
investigations in later years. (Bower (22), Goebel (21), Clapp (i).)
Miss Clapp studied the earliest stages of the embryo and found they
agreed with Leitgeb's account. The very much enlarged basal cell
is a true haustorium.

P. 95. The wall of the capsule in Aneura is two-layered through-
out.

P. 96. The apical mass of sterile tissue is known as an elaterophore.

P. 96. The spore mother cells in Aneura become strongly four-
lobed before the nuclear division takes place. This is generally
characteristic of the Jungermanniales.

APPENDIX 617

P. 98. The writer has investigated the development of the sporo-
phyte in Pallavicinia, Podomitrium, Calycularia, and Treubia. (Camp-
bell (34, 37, 39, 40).)

In Pallavicinia (Campbell and Williams (37) ) the young embryo
develops a very conspicuous haustorium, which is composed of several
cells instead of being unicellular as in Aneura, and in Podomitrium
(Campbell (39) ) and Treubia (Campbell (40) ) the haustorium forms
a large mass of cells below the foot. In none of these genera is the
separation of the sporogenous area so early differentiated as in
Aneura.

There is a good deal of variation shown in the development of the
sporophyte in different species of Pallavicinia. Thus in P. Zollingeri,
which belongs to the section Mitteriia, the sporogenous area in the
young capsule is quite limited and forms a convex disc, which in
vertical section appears as an arc composed of narrow cells arranged
in vertical rows, the tissue below forming a sort of columella, which
later disappears with the increased growth of the sporogenous tissue.

P. radiculosa and P. Levieri show a larger amount of sporogenous
tissue in the young sporophyte and the capsule becomes very much
elongated, especially in the former species. These species belong to
the section Eupallavicinia. P. Zollingeri has a shorter capsule, which
is more clearly separated from the seta than is the case in any species
of Eupallavicinia that were examined ; and there is a distinct some-
what bulbous foot developed, while in Eupallavicinia the foot is much
less developed. In both respects Mittenia comes nearer to the genus

M'orkia.

In all of the species of Pallavicinia the apical portion of the capsule
wall is thicker than the lateral walls, this being most marked in
Eupallavicinia, where the apex is pointed and forms a beak some six
or eight cells deep, while the lateral walls of the capsule are composed
of but three or four layers of cells.

Podomitrium Malaccense (Campbell (39) ) much resembles Palla-
vicinia in the development of the- sporophyte, but there is a small
apical elaterophore like that of Aneura, and the foot is clearly marked
by a constriction as it is in M'orkia or Calycularia. (See Campbell

(34).)

P. 98. In many cases, e.g., Pallavicinia Levieri, the calyptra is
not wholly derived from the venter of the archegonium, but the
tissue below the archegonium is involved so that with its growth
the unfertilised archegonia are carried up to the summit of the
calyptra.

6i8 MOSSES AND FERNS

The outer cells of the capsule have their cell- walls thickened, some-
times uniformly, e.g., Pallavicima, Podomitrium; sometimes with
thickened bars or partial spirals, e.g., Calycularia radiciilosa, Pellia.
In the latter genus there is a well-marked basal elaterophore, which is
perhaps represented in some other genera by the presence of a few
attached elaters at the base of the capsule.

A quadripolar spindle, very much like that in Pallamcinia decipens,
occurs in Calycularia radiciilosa, but sometimes a bipolar spindle is
formed, followed by two others, and this is also the case in Palla-
vicinia radicidosa and P. Levieri (Campl^ell (37) ). In the latter there
is no evidence of a quadripolar spindle.

P. 99. The dehiscence of the capsule may be by a fragmentation
of the wall, e.g., Fossomhronia, or by splitting longitudinally into more
or less regular (usually four) valves. In Aneura and Metzgeria this
spUtting includes the elaterophore, which with the adherent elaters
forms four tufts at the free ends of the valves. In Pallamcinia the
valves are united at the tip, and the spores escape through four slits
between the valves. Cavers (9) states that in Podomitrium the
valves are also adherent at the apex, but the writer's studies on P.
Malaccense indicate that in this species the splitting extends to the
apex of the capsule, but there are only two valves instead of four.
Calycularia radiculosa (Campbell (34) ) sometimes has these valves
adherent at the apex, but occasionally separated completely. As in
the case of Podomitrium Malaccense there are but two valves, each of
which, however, is clearly formed of two coherent valves. According
to Schiffner the other species of Calycularia have the wall broken up
irregularly on dehiscence, as in Fossomhronia, and he thinks they
should not be associated, generically, with C. radiculosa.
P. 100. For Goebel (13), read (15).

P. 100. Cavers (9) has proposed the name Calobryaceai as a
substitute for Haplomitrea^. The best-known species of the family
is Calobryum Blumei, a very beautiful Liverwort, occurring in the
Indo-Malayan region. For details see Goebel (15).

P. loi. It seems almost impossible to clear up the relationships
of the Anacrogyna?. Cavers recognises two main lines of develop-
ment, which he thinks have diverged from the Sphccrocarpus type.
These he calls the Pellia line (comprising the Codoniaceae and Calo-
bryaceai) and the Blyttia line (Aneuraceai and Blyttiacea?). In both
of'these there has been the development of leaves, and the question
arises as to which of these leafy Anacrogynae is nearer to the leafy
acrogynous Liverworts.

APPENDIX 619

Two theories have been advanced. Cavers believes all of the
Acrogynse have arisen from the same type, and of the existing Anacro-
gynse he thinks Fossombronia represents most nearly this hypothetical
ancestor.

Spruce (2) has argued that there is good reason to separate the
Acrogynae into two series, one Jubuloideae (= Lejeuneacea^), which
perhaps arose from Metzgeria-like ancestors ; and the Jungermanneae
(including all the other Acrogynae), which have been derived from
forms like Fossombronia.

Fossombronia differs a good deal from the typical Codoniaceae, and
shows some suggestive resemblances to the Sphaerocarpales, especially
to Geothallus. Petalophyllum is another genus, usually referred to the
Codoniaceae, which is also perhaps related to Geothalhis. It is possible
that there is a distinct series of related genera leading from Geothalhis,
through Petalophyllum and Fossombronia, to Treuhia. The latter,
on the whole, probably comes nearest to the typical Acrogynae.

P. 10 1. The archegonia are not necessarily confined to special
branches, but in some genera, e.g., Plagiochila, Gottschea, are borne
at the apex of the main axis. In most genera several archegonia are
formed before the apical cell is transformed into an archegonium, but
in Lejeunia a single archegonium only is present, and in Frullania

usually two.

The archegonial group is usually surrounded by an outer sheath
(perichiEtium) composed of a whorl of more or less concrescent
leaves, within which is developed the second envelope, or perianth.

P. 106. The early divisions in the antheridium of Pallavicinia and
Podomitrium agree exactly with those in Porella, and further investiga-
tion will probably show that this method of division, in the anther-
idium, is more common than has been supposed to be the case.

P. 107. The spermatogenesis of Porella has been recently de-
scribed in detail by Woodburn (i).

P. 112. There is a second layer of cells in the wall of the capsule
in Porella, which is not clearly indicated in Fig. 57.

P. 112. The embryo of Frullania is so different from that of most
of the Acrogynae, that Spruce (2) has removed the family Lejeuneaceae,
to which it belongs, from the other Acrogynae and estabhshed a special
order, Jubuloideae.

P. 113. For Goebel (12), read (14).

P. 114. For Goebel (13), read (14).

P. 117. Evans (4) has recently made an exhaustive study of the
branching in the Acrogynae.

620 MOSSES AND FERNS

P. 119. The following classification of the Acrogynae is taken with
some slight changes from Cavers' recent resume of the Bryophytes
(Cavers (9) ). It is based upon Spruce's work (Spruce (2) ).

A. Leaves various as to form and insertion ; capsule usually long-
stalked ; elaters various but never attached or extending from the
apex to the base of the capsule ; each elater with two or more spiral
fibres ; archegonia always four or more in a group.

Families — Lophoziaceae (Epigonanthea}), Cephaloziaceae (Trigo-
nantheae), Ptilidiaceas, Scapaniaceae, Radulaceae, Porellaceae.

B. Leaves typically divided into a large upper and a small lower
lobe, the latter usually rolled up or saccate ; under leaves (amphi-
gastria) usually present ; elaters few, with a single spiral fibre, all fixed
by the upper end to the apex of the capsule and extending to the base
of the capsule cavity ; archegonia from one to four (rarely more) in
a group. Fam. i — Lejeuneaceae.

Cavers considers the Lophoziaceae to be the lowest forms, connect-
ing the other Acrogynae with Anacrogynae of the type of Fossombronia;
the Lejeuneaceae he places at the top of the acrogynous series.

Spruce, however, as already stated, regards the Lejeuneaceae
(Jubuloideae) as entirely unrelated to the other families of the Acro-
gynae.

CHAPTER IV

P. 120. A fourth genus, Megaceros, is based upon material collected
by the writer in Java. (Campbell (30).)

P. 121. In Megaceros there are several chromatophores in each
cell, sometimes a dozen or more in the large inner cells of the thallus.

In Anthoceros Pearsoni, which resembles Megaceros, also, in having
soUtary antheridia, there are usually two chromatophores in the inner
cells.

P. 128. Peirce (2) concludes from a study of Anthoceros grown
upon sterilized soil, and therefore free from Nostoc, that the presence of
the latter in the thallus is rather detrimental than otherwise.

P. 128. For Waldner (2), read (i).

P. 132. For Janczewski (2), read (i) ; for Waldner (2), read (i).

P. 141. The species of Anthoceros with spiral elaters should be
transferred to the genus Megaceros.

P. 145. For Goebel (22), read (21).

P. 145. The genus Megaceros was established by the writer, to
include a number of species which had been included in Anthoceros, but
which differ from that genus in certain important particulars.

APPENDIX 621

The species of Megaceros are mostly tropical, and they are especially
common in certain parts of the Malay Archipelago. The writer has
collected them at various stations in Java, Sumatra, Borneo, and
Luzon. Some of the species are very large and conspicuous, and occur
in masses covering the rocks in stream-beds and similar locaUties.
Others grow on rotten logs, and less commonly on the ground.

The thallus usually closely resembles that of the larger species of
Anthoceros, and the apical growth in the species investigated by the
writer is exactly the same. The most obvious difference is the
presence of several chromatophores in the cells, sometimes as many
as twelve having been observed in the inner cells. Usually no
pyrenoid can be recognized, and the chromatophores are much like
those of the higher plants.

The antheridia are large, and borne singly as in Dendroceros or
Anthoceros Pears oni.

The sporophyte in its earlier stages is most like that of Dendroceros^
but there is a much larger development of the sporogenous tissue,
which suggests the condition found in Notothylas. The spores at
maturity contain chlorophyll, a condition found also in Dendroceros,
but not in Anthoceros, and the elaters have spiral thickenings as in
Dendroceros. Like the latter, stomata are absent.

Megaceros is thus a sort of synthetic type, combining characters
found in all three of the other genera. (See Campbell (30).)

P. 148. The writer has investigated two species of Dendroceros
from Java (Campbell (30, II) ), which agree closely with the other
species that have been examined.

P. 156. Lang (7) states that in a species of Notothylas from Singa-
pore (probably N. Breutelii), while the early stages of the embryo
agree with the other Anthocerotaceae, and the primary sporogenous
tissue originates from the amphithecium, the upper portion of the
columella develops spores, so that the latter arise in part from the
endothecium. A similar condition, but less marked, was found by the
writer in A^. Javanicus. (Campbell (30, II).)

P. 159. While there are certain similarities between the young
sporophyte of the Anthocerotaceas and such Liverworts as Sphcero-
carpus, Cyathodium and especially Fossomhronia, the fact that the
primary sporogenous tissue in the Anthocerotales always arises from
the amphithecium, while in all other Liverworts it is developed from
the endothecium, would seem to be a radical difference. Cavers,
however, thinks that the differences between the Anthocerotaceae and
the other Liverworts are not sufficient to warrant removing the Antho-

62 2 AIOSSES AND FERNS

cerotaceae from the Hepaticae, and he regards the order Anthocerotales
simply as an order of Hepaticas co-ordinate with the Marchantiales
and Jungermanniales.

P. i6i. For Leitgeb (2), read (4).

CHAPTER V

P. 166. Cavers (9), in his review of the Musci, divides the Bryales
into four groups, which he thinks should have the rank of orders, viz.,
Tetraphidales, Polytrichales, Buxbaumiales, and Eu-Bryales.

P. 170. In submerged plants the whole stem consists of uniform
tissues, all the cells except the innermost ones having chlorophyll.

P. 173. Oltmanns (i) has made a careful study of the mechanism
by which water is taken up by Sphagnum. In most species this is
effected by capillary action, due to the numerous pendant branches,
which are closely appressed to the stem, and between which the water
ascends by capillarity. In species like S. cymbifolium, however, in
which the cortical cells contain pores and fibres on their walls, these
cortical cells play an important role in the absorption and conduction
of water.

P. 177. The development of the archegonium has been carefully
studied by Bryan (i). It shows some interesting suggestions of the
Liverwort-archegonium in having the apical growth much less
marked than in most Mosses, and in having all of the neck canal-cells
formed from the division of a primary canal-cell. There are eight or
nine canal-cells. "Abnormalities, such as double venters, multiple
eggs, etc., are of common occurrence."

P. 182. For (Ruhland (2) ), read (i) ).

CHAPTER VI

P. 195. The statement that Funaria is dioecious is incorrect. The
antheridial shoots develop first, and later, as lateral branches from
these, the shoots bearing archegonia arise. (See Boodle (7).)

P. 197. The spermatogenesis of the Mosses has received a good
deal of attention in recent years. The latest contributions are those
of Woodburn (3) and Allen (2), who investigated the spermato-
genesis in Mnium ajfine and Polytrichum jiinipcrinum.

The development of the spermatozoid is much like that of other
Bryophytes that have been examined. In Mnium there are six

APPENDIX 623

chromosomes in the nucleus of the sperm-cell, and there is often
present a vacuole, whose contents it is thought contribute to the growth
of the spermatozoid.

P. 199. For Goebel (22), read (21).

P. 203. The relation of the protonema to the spores in dioecious
mosses has been carefully investigated by Marchal (i, 2), in three
species, viz., Barbula unguiculata, Byrum argenteum, and Ceratodon
purpureus. The results obtained were the same in all species and
may be summarized as follows :

1. The spores in a capsule are of two kinds, as to their sexual
character.

2. The spores are "unisexual," i.e., some produce a protonema of
which all the shoots are male, while the protonema developed from
the others bear only female branches.

3. The sexual character is perfectly transmitted through the
medium of secondary protonemal filaments, and by buds of different
sorts, some of these giving rise to shoots of a different sex.

4. The action of environmental factors, within a single generation,
is incapable of changing the sex-character of the protonema.

P. 203. Bryan (2) has recently examined the development of
the archegonium in Catherinea angustata, which does not differ
materially from other species that have been investigated.

P. 214. The division of the Bryales into Cleistocarpae and Stego-
carpae is not a natural one, and probably should be abandoned. The
same may be said of the "Acrocarpi" and "Pleurocarpi," which do
not represent a natural division, both acrocarpous and pleurocarpous
forms sometimes occurring in the same genus, e.g., Fissidens.

P. 216. For Goebel (22), read (21).

P. 218. Tetraphideas = Tetraphidales (Cavers (9) ).

P. 221. Polytrichaceae = Polytrichales.

P. 225. Buxbaumiaceae = Buxbaumiales.

CHAPTER VII

P. 234. The writer, in 1906, discovered in Java the gametophytes
of several species of OpJnoglossum, including 0. Moluccanum (probably
identical with 0. pedunculosum) and 0. pendulum. In the former
species the gametophyte is subterranean, and apparently lives but one
season ; in the second, as Lang already found, it is buried in the mass of
humus collected between the leaf-bases of epiphytic ferns (in this case

624 MOSSES AND FERNS

Asplenium nidus). From the position of the older gametophytes, it
was clear that they had been growing for many years, and Bruchmann
(5), in his study of the prothalhum of 0. vulgatiim, found this was
also true in that species.

The spores of O. Moluccanum germinate in a few days, and divide
into three or four cells, growing at the expense of the food materials
in the spore, which is destitute of chlorophyll. Faint traces of chloro-
phyll were noted in a few cases, but after exhausting the food matter
in the spore, the young gametophyte, in all cases, finally died.

In O. pendulum, where the early divisions occur later than in O.
Moluccanum, in several cases the young gametophyte associated itself
with a fungus, as a result of which its growth was stimulated. It is
pretty certain that this association with the fungus is a necessary
condition for the further development of the gametophyte. (Camp-
bell (29, 7,3) -)

The fully grown gametophytes of O. Moluccanum are very delicate,
slender, cylindrical bodies, 5-10 millimetres in length. None of those
found by the writer were branched, and they were much smaller
than those of O. pedunculosum, figured by Mettenius ; but otherwise
they were very similar. In 0. vulgatum, also, the gametophyte is
larger, and may be branched (Bruchmann (5) ). Bruchmann found
that when the gametophyte in O. vulgatum was exposed to the light
it developed chlorophyll. The writer was unable to induce the forma-
tion of chlorophyll in the gametophyte of O. pendulum.

The gametophyte of O. pendulum is much more massive than that
of the other species, and is very variable in form. Usually there are
several stout branches radiating from a common centre. The largest
specimen found was about fifteen millimetres in breadth. The form
is determined by the position of the numerous roots of the host-fern,
among which the branches of the OpJiioglossum gametophyte ramify.
The branches are very easily broken off, but at once enter upon an
independent existence, and this power of reproduction accounts for the
very great age (probably more than twenty years) which some of the
prothallia show. Under special conditions buds may develop which
further facilitate the multiplication of the prothallia.

P. 235. The endophytic fungus, or "mycorrhiza," is especially
conspicuous in O. pendulum, where it is found in all but the youngest
parts of the branches of the prothallium. A cross-section of a branch
shows a broad zone of infected tissue, which lies between a central
pith and several layers of peripheral cells, which are nearly or quite
free from the fungus.

APPENDIX 625

As the mycorrhiza invades the cells of the young tissue, their con-
tents are mostly destroyed, except the nucleus, which remains intact.
In the earlier stages the hyphae are nearly uniform in thickness, but
later they undergo a sort of degenerative process, forming vesicular
thin-walled masses, which seem to be finally destroyed by the action
of the prothallium cells. "Symbiosis" thus would seem to be a case
of mutual parasitism, the fungus being active in the earlier stages, but
later being destroyed by the activities of the host-cells.

P. 236. The sex-organs in both O. Moluccanum and O. pendulum
arise in acropetal succession, the youngest ones being close to the
apex of the branch. There is no definite relation of antheridia and
archegonia, the two being irregularly intermingled.

P. 237. For details of the development of the antheridium, see
Campbell (29, ^t,).

P. 237. The spermatozoids are probably the largest known among
the Pteridophytes. Those of O. pendulum are larger than those of
O. Moluccanum, but the nuclear portion is less elongated.

Just before the final division of the sperm-cells, the nucleus shows a
small but distinct nucleolus, and in favorable preparations two small
rounded bodies, the blepharoplasts, can be distinguished. The
chromosomes are very numerous, but the number could not be deter-
mined.

After the final mitosis is completed, the nucleus shows a coarse
reticulum, but no nucleolus can be seen. Before any evident change
occurs in this nucleus, the blepharoplast becomes elongated, and forms
a delicate thread which stains strongly with gentian-violet.

The nucleus next elongates slightly, and the reticulate appearance
becomes very conspicuous. In the reticulum are large strongly
staining chromatin masses, which apparently arise from the coalescence
of several chromosomes. The nucleus now becomes indented on one
side and in profile appears crescent shaped. As it elongates it assumes
the form of a curved thickened band, tapering at the forward end,
which is sharply pointed. The chromatin masses become more and
more coalescent, until finally the elongated curved nucleus appears
almost perfectly homogeneous.

The blepharoplast now becomes a spiral band, which connects with
the nucleus, and with it forms the body of the spermatozoid. The
central part of the cell contents is enclosed in the coil of the spermato-
zoid, and probably, as in other Ferns, forms a vesicle attached to the
free-swimming spermatozoid.

The cilia begin to appear as short outgrowths of the blepharoplast,
40

626 MOSSES AND FERNS

before the nucleus has changed its form. They increase much in
length, and are very numerous.

P. 237. The writer found in O. pendulum that the neck canal-cell
not infrequently became completely divided into two cells. The
ventral canal-cell is difficult to demonstrate, and it often looks as if
no ventral canal-cell were formed. Probably it is formed just before
the dehiscence of the archegonium, and is very transient.

P. 238. Bruchmann (6) has given a very complete account of the
gametophyte of B. Lunar ia, which closely resembles the younger
stages of B. Virginiamcm. The archegonia are on the dorsal surface,
as in B. Virginianuni, and not on the ventral side, as Hofmeister
states is the case.

P. 242. The writer collected the older prothallia of HeJmintho-
stachys in Ceylon at the same station where Lang secured his material.
They were in forest land, which was subject to annual flooding, and
it is probable that this is necessary for the germination of the spores.
The gametophyte appears to be annual, dying after the establishment
of the sporophyte.

P. 242. The development of the embryo was investigated by the
writer in Ophioglossum Moluccamim and O. pendulum. (Campbell
(29, ^T,).) In both of these the first division is approximately trans-
verse and divides the embryo into two nearly equal cells, an
''epibasal" and ''hypobasal." From the hypobasal cell, in both
species, a large hemispherical mass of tissue is developed, the foot,
while from the epibasal half the other organs of the young sporophyte
ultimately develop.

Both species show an unexpected deviation from the usual fern-
type. In O. Moluccamim the epibasal portion develops into a
conical body, with a definite apical cell, and this later expands at the
summit into the lamina of the spatulate cotyledon, or primary leaf.

In the middle region, deep in the tissue near the base of the foot
(probably from the epibasal tissue), there arises a group of cells which
begin to divide actively, and form the beginning of the primary root,
which grows downward in the same plane as the cotyledon, and push-
ing through the tissue of the foot, breaks through it and the overlying
gametophytic tissue, and penetrates into the ground.

The root grows from a tetrahcdral apical cell, and there is soon
evident an axial strand of elongated cells, the ^' stele" or young
vascular bundle, and this continues without interruption into the
corresponding stele of the young cotyledon. All that remains of the
foot is a slight enlargement in the middle of the young sporophyte,

APPENDIX 627

which nov/ shows a markedly bipolar structure, the young plant con-
sisting of only the leaf and root, whose tissues are perfectly continuous.
At this stage, absolutely no trace of any stem-structure is present.

In O. pendulum the hypobasal part of the embryo, as in 0. Moluc-
camim, gives rise to the large foot ; but the epibasal portion, instead of
developing into the cotyledon either at once grows out into a
single root, or, after a vertical division, each half may form an in-
dependent root. These roots (or root) grow for a long time,
and may branch without any evidence of a leaf being seen. The
development of the leafy shoot is not known, but it is highly probable
that the first leaf arises from an endogenous bud upon the root.
Bruchmann (5) has studied the embryo in 0. vulgatum, but was
unable to find the youngest stages. It resembles more nearly that of
O. pendulum, than O. Moluccanum, in the early development of the
root, which makes up the greater part of the embryo before any trace •
of a leaf or stem-apex can be recognized. The stem-apex, according
to Bruchmann, arises near the base of the root, and is of superficial
origin ; but his figures suggest the possibility of an endogenous origin
similar to that of O. Moluccanum. In O. vulgatum the first leaves are
rudimentary, and remain permanently underground. It is several
years (8-10 according to Bruchmann) before the first green leaf
appears above ground.

In O. Moluccanum, at the time the first leaf is completely developed,
the young sporophyte consists simply of this leaf, whose lamina shows
the characteristic netted venation of the older plant and the root.
The slender petiole is continued directly into the root, it being im-
possible to determine where the petiole ends and the root begins.

In the stele of the leaf the single protoxylem arises on one side, and
the bundle at maturity has the "collateral form." The single xylem
of the leaf-stele is continued into the root as the single xylem of its
''monarch" bundle.

Mettenius's account of the development of the embryo in 0.
pedunculosum agrees closely with the writer's studies on O. Molucca-
num. Mettenius describes the origin of the stem-apex as a bud
upon the root, but did not investigate its exact origin, but it no doubt
is the same as in O. Moluccanum.

In the latter the first evidence of the permanent growing-point of the
sporophyte is the formation of a group of meristematic cells close to
the stele of the root, very much, indeed, like the origin of a secondary
root. From this meristem there are differentiated a leaf and the
stem-apex, apparently quite independently of each other. The

628 MOSSES AND FERNS

leaf grows quite rapidly, and soon ruptures the overlying tissues, and
appears on the outside of the root. It develops a vascular bundle
which joins directly with that of the primary root.

The stem-apex consists of a shallow mass of tissue with a conspic-
uous apical cell, but no indications of any vascular bundles, and
throughout the life of the sporophyte there are no cauline bundles, the
whole vascular system being composed of the united leaf and root traces.

P. 243. The writer's later studies on Botrychhim make it probable
that, as in Ophioglossum, there is no proper stele in the stem of Botry-
chium, but that all of the vascular tissue of the axis belongs to the
leaf-traces and roots. (See Campbell {^i).)

P. 243. Fourth line, for epibasal, read hypobasal.

P. 244. Lyon (2) found in B. obliquum a well-marked suspensor,
and Lang (9) states that a suspensor is also developed in Helmintho-
stachys. The early development of the latter is only imperfectly
known, but to judge from later stages (Campbell {t^t^) ), it is more like
Botrychium than like Op/iioglossiim.

For a detailed account of the development of the vascular system
in the young sporophyte of the Ophioglossaceae see Campbell (ss)-

P. 245. A full account of the general morphology of the Ophio-
glossales has been given by Bower (22).

P. 245. The genus Ophioglossum has been divided into three sub-
genera, perhaps better considered as distinct genera. Euophioglossum
includes the great majority of species, Cheiroglossa has but one species,
0. palmaliim, while Ophioderma has three: O. pendulum, O. simplex,
and O. intermedium.

P. 248. The apical cell in 0. Moluccanum and O. reticulatiun is
either a three-sided or four-sided prism, the apex of which is smaller
than the base.

P. 250. In O. Moluccanum, and probably in all species of Ophio-
glossum, the whole vascular system of the adult sporophyte (except
the root) is made up of the leaf traces, which join so as to make a large-
meshed hollow cylinder. There is no proper cauline stele.

The bundle from each young leaf can be traced to a junction with a
root-stele, and from the point of junction it extends through the tissue
of the axis, running almost horizontally until it joins the trace from
the next older leaf. In this way is built up the open, large-meshed
vascular cylinder. So far as could be determined, in O. Moluccanum
only one root is formed for each leaf. The tissues of the root-base are
continued upward to connect with the young leaf, and downward to
join the stele from an older one.

APPENDIX 629

No endodermis can be seen in O. viilgatum or O. Moliiccamwi, but
in some other species, e.g., O. Bergianum, there is, according to Poirault
(3), both an inner and an outer endodermis in the older part of the

rhizome.

For details of the stem-structure see Campbell (33).

P. 250. In 0. Moluccanum (see Campbell (33) ) the sporangio-
phore arises very early in the development of the sporophyll, and
there is virtually a dichotomy of the young sporophyll resulting in
the sporangiophore and the sterile lamina. Bruchmann (6) found
much the same state of affairs in Botrychium Lunaria.

P. 252. In all species of Eiiophioglossiim there is given off from
the vascular system of the rhizome a single leaf-trace, which divides
at the base of the petiole into two strands, each of which may divide,
or only one of them. In the larger species there are further divisions
so that a section of the petiole shows a ring of several bundles. In
some species there are large air-spaces in the petiole, while in others
these are absent. (For details see Campbell {^^).)

In O. pendulum the leaf-trace is composed of a number of strands
where it joins the vascular cylinder of the rhizome.

P. 254. For Goebel (17), read (9).

P. 254. In large roots of O. pendulum there may be three or four,
or even five, xylem masses, arranged radially.

P. 257. The tapetum is derived, not from the archesporium, but
entirely from the inner cells of the wall of the sporangium (Burlingame
(i) ). Bower, in a later study of the spore-formation, found that
all of the sporogenous cells developed spores.

P. 258. Specimens of O. pendulum collected by the writer in
Ceylon and Java, were much larger than the Hawaiian plants, some-
times upward of 1.5 meters in length. These usually had the lamina,
and sometimes the spike, dichotomously branched.

P. 270. For Goebel (22), read (21).

P. 272. It is probable that all of the sporogenous cells undergo the
normal tetrad-division in all the Ophioglossaceae. (See Bower (22),

P-457-)

CHAPTER VIII

P. 273. A sixth genus, Macroglossiun, has been recently described.
(Copeland (i).)

P. 274. The writer has also investigated the gametophytes of
several species of Dajiced, Kaulfussia, and Macroglossum. (Campbell
(33, 36).)

630 MOSSES AND FERiVS

P. 276. The prothallium of Anglo pter is (see Campbell (33) )
not infrequently has the usual heart-shape, or may even be consider-
ably elongated. Where fertilization is prevented, it may reach a
very large size. Gametophytes of three centimeters or more in
length have been observed by the writer in Dancea, and almost as large
ones in Kaiiljiissia and Macroglossum. These large prothallia are
often branched, four growing points being noted in one case. (For
details see Campbell (33).)

P. 280. The archegonium of the other genera closely resembles
that of Marattia. In Kauljnssia it is rather larger, and in DancBa
the ventral canal-cell is very difficult to demonstrate, indeed, it looks
as if it were absent in many cases. In this respect, DancBa recalls the
behaviour of Ophioglossum.

P. 281. The writer has investigated the development of the embryo
in all of the genera except Archangiopteris. (See Campbell {t^t^, 36).)
There are some marked differences shown in the different genera. In
all cases the primary (basal) wall is transverse, and in Marattia,
Kauljnssia, and Angiopterls the whole of the egg takes part in the
development of the embryo ; but in DancEa and Macroglossum there
is a suspensor formed. In the former the fertilised egg elongates be-
fore the basal wall is formed, and the cell next the opening of the
archegonium, i.e., the lower or hypobasal cell, develops into a short
suspensor, while the whole of the embryo proper is derived from the
epibasal portion of the two-celled embryo.

In Macroglossum (Campbell (36) ) the suspensor is much larger,
but its origin is not quite clear.

P. 282. In Marattia, Angiopteris, and Kaulfussia the basal wall
divides the embryo into two nearly equal parts, the hypobasal cell
(that next the archegonium neck) giving rise to a large, nearly hemi-
spherical foot ; from the inner or epibasal cell the cotyledon is
developed, and later the stem-apex. The young embryo is decidedly
flattened at first, but later becomes almost globular, and then elon-
gated vertically. At this stage the embryo is bi-polar, as it is in
Ophioglossum.

No trace of a root can be recognised until the embryo has reached
a considerable size. Then there may be seen near the junction of
the foot and cotyledon, near the centre of the embryo, a group of
active cells, which it is soon evident constitute the growing point of
the primary root, which is thus seen to originate in exactly the same
way as it does in Ophioglossum Moluccanum'. A single apical cell is
present, which is somewhat variable in form. The root finally pushes

APPENDIX 631

through the foot, which thus becomes practically obUterated, and
breaking through the overlying prothallial tissue penetrates into the
earth.

From the epibasal region there is developed the cotyledon, whose
axis is almost coincident with that of the primary root. Close to the
base of the cotyledon, which comprises the major part of the epibasal
half of the embryo, a second inconspicuous prominence arises, the
stem-apex. A single apical cell is probably present in all cases.
Tt is somewhat variable in form, usually four-sided in cross-section, but
sometimes triangular. The base is usually, but not always truncate.

Both cotyledon and root elongate rapidly, and the young sporo-
phyte now closely resembles the corresponding stage of Ophioglossum
Mohiccamim, except for the presence of the stem-apex, which however,
is very inconspicuous. As in Ophioglossum the primary vascular
bundle extends as an uninterrupted strand from the cotyledon into
the root, and there is no stele developed in the stem region. In
Dancea the vascular bundle of the cotyledon is collateral as in Ophio-
glossum, but in the other genera it is concentric, although the phloem
is less developed on the inner side, and the bundle may approximate
the collateral type.

As the second leaf develops it also shows an axial bundle which is
continued downward as the second leaf-trace, and unites with the
primary bundle to form the beginning of the vascular system of the
axis. No stelar tissue is developed in the stem region above the junc-
tion of the leaf- traces.

P. 286. The cotyledon in Kaulfussia closely resembles that of
Ophioglossum, being oval in form and with reticulate venation. The
cotyledon in Dancea is similar in form to that of Kaulfussia, but the
venation is more or less completely dichotomous, with free veins.
In the other genera, the cotyledon is usually fan-shaped, with dichoto-
mous venation, but in Angiopteris and Macroglossum the venation
may be more or less pinnate in character.

P. 287. The statement that the primary root of Marattia is
tetrarch is erroneous. It is usually diarch in all the genera, but may
be, exceptionally, triarch.

P. 288. The development of the vascular system was critically
studied by the writer in Dancea and Kaulfussia, and to some extent
also in Marattia and Angiopteris (see Campbell {^3) ). All of the
genera agree as to the essential points of development.

The vascular system of the young sporophyte begins as a single
axial strand which is continuous through the cotyledon and root. At

632 MOSSES AND FERNS

a very early period a second vascular bundle or stele is formed in the
second leaf, and this stele joins the primary axial bundle of the young
sporophyte. In Dancea, which was especially studied, a similar
single stele is formed in each succeeding leaf, up to about the seventh.
Up to this time, except for the steles of the secondary roots, the whole
vascular system is built up of united leaf-traces, and there is no cauline
stele in the strict sense of the word, although one may speak of the
bundle or stele of the stem, as soon as there is a solid central strand
formed by the junction of the early leaf-traces. This primary stele
never has the character of a true protostele, as the xylems belonging
to the component leaf-traces can be clearly recognized, and the com-
pound nature of the stele is unmistakable.

At a later stage, about the time the seventh leaf is formed, there
arises a single axial ("commissural") strand, which is really of cauline
origin, and the only part of the vascular system which strictly belongs
to the stem. The leaf-traces formed subsequent to the appearance
of the commissural strand are double.

In the older sporophyte the vascular system of the axis has the form
of an open wide-meshed cylinder (''Dictyostele"), within which is the
commissural strand (or strands).

P. 290. The "meshed zones," are really built up of the very
complicated leaf-traces from the gigantic leaves, which sometimes
measure 5-6 metres in length.

P. 291. The statement of Holle (2), that sclerenchyma is present
in the stem of DancBa, was based upon an error, the plant examined by
him not being a Dancea, or any Marattiaceous fern. Dancea, like
all the other Marattiaceae, has no sclerenchyma in the stem.

P. 292. For Brebner (2), read (i) ; for Luerssen (7), read (6).

P. 292. Archangiopteris and Macroglossum, like Angiopteris, have
separate sporangia.

P. 297. An examination, by the writer, of sections of sporangia of
several forms of Angiopteris, showed a structure corresponding to that
given by Professor Bower.

P. 298. In Macroglossum (Campbell (36) ) the elongated sori are
separated by an elevated ridge, not unlike that found in Dancea.

P. 298. Probably the four sub-families given may better be
considered as families, viz., Angiopteridaceai, Marattiacea;, Kaul-
fussiaceae, Danaeaceae. The Angiopteridacea? now includes also
Macroglossum.

P. 299. KaidjHssia = Christensenia. A second species, C. Cumin-
giana, has recently been discovered in the Philippines.

APPENDIX 633

P. 298. All of the forms of Angiopteris have been referred by some
writers to a single species, A. evecta, but there is no question that
there are a number of well-marked species, although probably some
of the species recognised by De Vriese (i), should be eliminated.

P. 300. The genus Macroglossum was first described by Copeland
(i), from material sent from Sarawak in Western Borneo, where it
has been collected at several points. A form of this, probably a
second species, has been cultivated in the Botanical Garden at Buiten-
zog, Java, under the name Angiopteris Smithii. Macroglossum has
also recently been reported from Sumatra. Macroglossum, unlike
Angiopteris, has simply pinnate leaves, and the structure of the sporan-
gium is more like that of Archangiopteris, to which it is more nearly
related than it is to Angiopteris. (See Campbell (35, 36).) The
type, M. AlidcB, is a large fern with leaves sometimes nearly four
metres in length.

P. 300. Some species of Dancea, e.g., D. elliptica, have an upright
rhizome, and the leaves arranged spirally.

P. 300. Chlorophyll may develop under certain conditions in
the gametophyte of Ophioglossum (see Bruchmann (5), Mettenius

(2)).

P. 301. The young embryo of Ophioglossum Moluccanum, re-
sembles very closely that of Anthoceros.

P. 303. The recent studies of the writer on the embryology of the
Marattiaceae and Ophioglossaceae show a much greater similarity
between them than was supposed to be the case. (See Campbell

(33).)
P. 304. The reasons for the assumption of a direct relationship

between the Ophioglossaceae and Marattiaceae have been given at

length elsewhere. (See Campbell {t,^).) The conclusions reached

may be briefly summarised. "From some form allied to the existing

species of Ophioglossum the whole Fern-series is descended. In this

series the leaf is the predominant organ, the stem, at first, being of

quite subordinate importance. This ancestral Fern was monophyllous

and the original leaf was a sporophyll, perhaps without any definite

sterile segment.

From this central type it may be assumed that several divergent
lines of development arose, of which only isolated fragments have
persisted to the present time.

The Marattiace^, as they now exist, probably do not represent a
single unbroken line of descent, but show evidences of a multiple
derivation from the primitive stock. The point of contact with the

634 MOSSES AND FERNS

Ophioglossales is probably in the neighbourhood of Helminthnstachys,
which, on the whole, most nearly resembles the Marattiales ; but it
is improbable that the solid synangium which characterises most of
the living Marattiaceae was derived from a group of distinct sporangia
like those of Botrychium or Helminthostachys; and it is more likely
that it originated from some structure more nearly resembling the
spike of Ophioglossum.

Angiopteris is, with little question, the most specialised of the
Marattiales, and has apparently departed furthest from the ancestral
type; while, on the other hand, Kaidfussia is probably the most
primitive of the existing genera.

On the whole, the Marattiales are nearer the Leptosporangiatae than
the Ophioglassales are, and it is likely that the Leptosporangiates are
derived directly from some ancient Fern-types, related to the living
Marattiales, but differing from any of the existing forms."

CHAPTER IX

P. 305. The number of species of the Eusporangiatae is much
larger than the figure given. Christensen (i) recognises 192 species
of Ophioglossaceae and Marattiaceae, but probably some of these
should be reduced.

P. 306. For Luerssen (7), read (6).

P. 308. A very careful study of Apogamy and Apospory has been
made by Farmer and Digby (12). It was shown that where gameto-
phytes arose by apospory, the nuclei contained approximately the same
chromosome number as the sporophytic tissues. In such cases, the
young sporophyte developed either as an apogamous bud or else arose
from an egg-cell which had not been fertilised.

In cases where the gametophyte arises in the normal way, i.e.,
from the germination of a spore having half the chromosome-number
of the sporophyte tissues, the formation of an apogamous sporophyte
is preceded by a migration of nuclei from one cell to another with sub-
sequent fusions of the nuclei, so that in this way the cells of the apoga-
mous sporophyte receive the double chromosome-number.

P. 311. Piliilaria Americana shows traces of a terminal annulus
like that of the Schizaeaceae (see Campbell (26) ).

P. 314. Mottier states that in Onoclea monoecious prothallia are
found occasionally, although dioecism is the rule (see Mottier (4) ).

P. 326. The origin of the stele of the young axis needs further
investigation. It is not at all unlikely that in the Leptosporangiate

APPENDIX 635

Ferns, as well as the Eusporangiatae, the vascular system of the axis
is composed entirely of united leaf-traces. Should this be so, the
bundle found in the stem-quadrant of the embryo would belong to
the second leaf and not to the stem itself.

P. 328. A very elaborate study of the vascular system of the
Ferns has been published recently by Tansley (2). This, like all of
the similar work of late years, is based on the assumption that the
stelar structures of the axis are of cauline origin.

P. 342. For "Goebel (10)," read ''(9)."

CHAPTER X

P. 346. Boodle (8) has observed much reduced male prothallia
of Todea, developed from spores which germinated within the closed
sporangium, where the latter were prevented from opening on
account of excessive moisture.

P. 360. The most recent study of the structure of the vascular
system in the Osmundaceae has been made by Sinnott (i). This is
principally concerned with the question of the formation of foliar
gaps. These were found to be present in all cases, although often
inconspicuous.

P. 366. The writer has investigated the gametophyte in several
species of Gleichenia, i.e., G. polypodioides, G. pectinata, G. dichotoma
(G. linearis), and G. Iccvigata. The first species belongs to the section
Eugleichenia, the others to Mertensia. G. polypodioides, which was
collected near Cape Town, has a smaller prothallium than the other
species, and one which more nearly resembles that of the Polypodiaceae
in form; while the other species have the prothallium often much
elongated, or with a conspicuous midrib, much as in Osmunda. In
these species, too, there are more or less conspicuous leaf-hke lobes,
so that the prothallium closely resembles such a Liverwort as Fossoni-
hronia. The larger prothallia are sometimes dichotomously branched.

The antheridia are usually confined to the ventral surface of the
gametophyte, but in G. Iccvigata they may also occur upon the dorsal
surface of the midrib.

In the older gametophytes there was always found an endophytic
fungus, like that occurring in the Marattiaceae and Ophioglossaceae.

The antheridium of Gleichenia polypodioides was found to correspond
most nearly with that of the species studied by Rauwenhoff ; in the
other species the antheridium is very much larger, and closely re-

636 MOSSES AND FERNS

sembles that of Osmunda. In G. lavigata the antheridium may reach
a diameter of 100 /u,, and contain several hundred sperm-cells.

P. 369. The cotyledon in G. pectinata, G. dicJwtoma, and G.
Icevigata shows a prolonged apical growth like that of the leaves of the
adult sporophyte. The early roots are diarch.

P. 372. Compton's work on M. sarmentosa (Compton (i) ) shows
that the anatomy of this species is somewhat simpler than that of
M. pectinata, but is not essentially different.

P. 372. Shreve (i) has made a special study of the physiology of
the Hymenophyllaceae.

P. 379. For Boodle (i), read (2).

P. 3S3. See the recent paper by Georgevitch (i).

P. 384. In a recent paper by Miss Twiss (i), it is stated that in
Aneimia Phyllitldis the two lobes of the heart-shaped prothallium are
of equal size.

P. 385. For Thomas (i), read (3).

P. 388. The sterile leaves of the majority of the species of Schizcca
are simple, as they are in S. pus ilia.

P. 388. The development of the sporangium in Aneimia and
Lygodium have been examined by Stevens (i), and Binaford (i).
Their results confirm the work of Prantl, but add some details to the
structure of the tapetum and spore-division. In both genera the
tapetum is two-layered. In Lygodium the cells often show two nuclei,
and only the inner layer of tapetal cells is broken down. In Aneimia
Phyllitldis, Stevens found that the w^hole tapetum becomes broken
down.

P. 395. The relationships of the families of the Filices to each
other, and especially the interrelationships of the Polypodiaceae, are
still by no means settled. Among the recent contributions to this
subject, may be mentioned especially the important series of papers
by Professor Bower on the phylogeny of the Filicales (27-31).

CHAPTER XI

P. 398. Two important contributions on the gametophyte of
Salvinia have recently been published: (Arnoldi (2); Yasui (i) ).

P. 398. Yasui's account of the development of the male gameto-
phyte confirms Belajeff's statement. He considers that there are
two antheridia formed, each containing four sperms. The results of
Axnoldi's investigation also confirm Belajeff's conclusions, Arn(»Mi

APPENDIX 637

studied the development of the spermatozoid, which does not differ
essentially from that of other Filicinea^.

P. 403. Both Arnoldi and Yasui found that the nucleus of the
spore cavity in Salvinia divides very much as in Azolla.

P. 407. Yasui (i) states that a primary root is present but it is not
functional, and soon ceases to be recognisable, becoming merged with
the foot.

P. 414. Yasui (i) confirms Heinricher's statement that the
tapetum in Salvinia is composed of a single layer of cells as in Azolla.
Like the latter there are but eight macrospore mother cells, instead
of sixteen as Juranyi states. According to Yasui there are sixteen
chromosomes in the spore mother cells, and the reduced number in
the spore is eight.

P. 414. For Juranyi (i), read (2).

P. 414. Footnote — " Macrospangium, " should be " macrosporan-
gium."

P. 426. For Arcangeli (i), read (2).

P. 435. The marginal position of the sporocarp is especially evident
in M. poly car pa (see Alhson (i) ).

P. 442. Some interesting experiments bearing on the origin of
heterospory have been made by Shattuck (i) on Marsilia.

P. 446. For Goebel (22), read (21).

CHAPTER XII

P. 446. The prothallium of Equisetum debile is described by
Kashyap (i) as being radial in structure, and resembling that of
Lyco podium cernuum; but the figures and descriptions are not very
convincing, and it is quite as likely that a more careful investigation
would show no radical difference between E. debile and the other
species that have been studied. The early stages resemble closely
those of E. telmateia, where (see text. Fig. 258) the young prothalUum
sometimes shows a condition corresponding to what Kashyap calls a
''primary tubercle."

P. 447. In E. debile (Kashyap (i) ) archegonia are formed first,
and later, on the same prothallium, the antheridia.

P. 447. The development of the spermatozoids has been very
exhaustively studied by Sharp (i). He states that the blepharoplast
at one stage becomes broken up into a series of bead-like fragments,
which later fuse into a continuous thread. He also states his beHef
that the blepharoplast is a further development of a centrosome.

638 MOSSES AND FERNS

P. 453. The extensive but interrupted marginal meristem noted
by Kashyap in E. debile, is probably the result of the repeated dichot-
omy of the primary apex. E. dcbilc has but a single neck canal-cell.

P. 454. Jeffrey's conclusions as to the origin of the root in the
embryo of E. hiemale and £. limosum are interesting, as they indicate
a resemblance to the Eusporangiate Ferns, especially Ophioglossum
and the Marattiales.

P. 457. E. debile agrees closely with E. hiemale in the early develop-
ment of the young sporophyte.

P. 459. For more recent investigations in the stem structure of
Equisctum see Fames (i), Sykes (i). Plant (i), Campbell (27).

P. 462. The development of the xylem in Equiselum has been
carefully examined by Fames (i).

P. 462. Miss Sykes (i) has described the presence of very large
reticulately pitted tracheids at the nodes in E. maximum. These
extend into the carinal canal of the internodal bundles, and it is
thought that their function is to conduct water from one internodal
bundle to another, as the carinal canals are interrupted at the nodes.

P. 464. The lacuna in the vascular bundle is known as the carinal

canal.

P. 467. The most elaborate study of the tissues of Eqiiisettim^
recently published, has been made by Plant (i).

P. 472. For Bower (15), read (14).

P. 476. Fig. 240 should be 279.

P. 478. Beer (3) states that the "middle layer" is formed through
the activity of the tapetal plasmodium. The membrane first formed
about the young spore is the exospore within which is later formed the
endospore. The middle layer is first deposited by the tapetal proto-
plasm, and later, outside of it is formed the perinium, from which,
by spUtting, the elaters arise.

P. 482. For a further discussion of the relationships of the Equise-
tales, see Campbell (27).

CHAPTER XTII

P. 483. For Goebel (18), read (10); for Bruchmann (5), read (4).

P. 483. Bruchmann (9) has succeeded in germinating the spores of
several European species of Lycopodium. See also Chamberlain (3),
Hollaway (2).

P. 485. It seems probable, from the more recent studies on the
Psilotacece, that the family should be made the type of a distinct

APPENDIX 639

order, Psilotales, and perhaps should even be removed entirely from
the Lycopodineae, and associated with the fossil order Sphenophyllales.
(See Lawson (i, 2).)

P. 486. Bruchmann succeeded in germinating the spores of three
European species, L. clavatum, L. amiotinum, and L. Selago. A
remarkable feature is the long period necessary for germination. In
L. Selago, the first signs of germination were seen in three to five years
after the spores were sown, while in the other species, six to seven
years passed before the spores began to germinate. Full-grown
gametophytes were first found in L. Selago, in six to eight years, in the
other species, twelve to fifteen years.

In all the species examined, the first division-wall cuts off a small
cell, which is apparently a rudimentary rhizoid. This is soon followed
by other walls, resulting in a globular or oval body composed of five
cells. There is then a long period of rest. This preliminary stage, or
"primary tubercle, " is reached at the expense of the food materials in
the spore, since the spores are without chlorophyll and the development
takes place underground.

As in the case of Ophioglossum, the further development is dependent
upon the symbiotic association of the young gametophyte with a
fungus. This takes place in the manner already described in Ophio-
glossum. (See note to p. 234.)

P. 489. For dioecious, read monoecious.

P. 492. Wernham (i), however, thinks that Phylloglossum "far
from being a primitive form is highly specialised."

P. 495. Holla way (i) has recently made an anatomical study of
several New Zealand species of Lyco podium.

P. 499. In a considerable number of species of Lycopodium
numerous roots are formed, which instead of emerging at once, grow
downward for a long distance through the cortical tissues of the stem,
emerging finally near the base. These were described by Strasburger
in L. Selago, and he enumerates about twenty species in which such
roots occur. They are especially conspicuous in L. pithy oides, an
epiphytic species.

P. 500. For Bower (15), read (14).

P. 502. The sporangium does not always, apparently, arise
directly from the leaf-base, but may be of axial origin. (Stokey
(2), Sykes (2).)

P. 503. The most recent work in Phylloglossum (Wernham (i) )
gives a detailed account of the structure. Wernham considers
Phylloglossum to be a much reduced form, and not a primitive

640 MOSSES AND FERNS

one. He calls attention to certain resemblances in its anatomy
to that of Isoetes and believes that the latter and Phylloglossum are

related.

P. 504. The gametophytes of both Psilotiim and Tmesipteris have
recently been discovered (Lawson, i, 2). The gametophytes are
much aUke, resembling in form that of Lycopodium Phlegmaria;
but the sexual organs are much more like those of the Ferns. The
spermatozoids are multiciliate. Lawson is inclined to accept the
view that the Psilotaceae are related to the Sphenophyllales.

P. 504. A study of the anatomy of P. flaccidum (Stiles (i) ) shows
a general agreement with P. triquetrum. In both species there is a
trace of secondary xylem in the stem-bundle. (See Boodle (6).)

P. 506. It is likely that Tmesipteris is saprophytic rather than
parasitic. As in other humus-saprophytes, there is always associated
with the plant a mycorrhizal fungus, similar to that found in the
Ophioglossaceae, and the subterranean gametophyte of Lycopodium.

P. 507. The Hterature on Tmesipteris has been carefully reviewed
by Miss Sykes (3), who also made a study of the structure of the
sporophyte. She considers the sporangiophore to be a branch having
two leaves, and terminated by a synangium composed of one or two
spongenous masses that have fused over the apex of the shoot. This
contradicts the view held by Bower.

P. 510. For Bower (21), read (20).

P. 510. Miss Sykes concludes that the evidence for associating
the Psilotales with either the Sphenophyllales or Lycopodiales is
inconclusive. ''They are better retained alone in the cohort Psilo-
tales."

P. 518. There is a good deal of difference in different species as
to the time of development of the gametophyte within the macro-
spore. (See Bruchmann (8).) Thus, in S. spinulosa and 5. Hel-
vetica the gametophyte is mostly developed after the spores are shed ;
while in S. rupestris the whole development of the gametophyte is
completed while the spores are still within the sporangium. Fertilisa-
tion may even occur while the spore is still within the sporangium
(e.g., S. apus), thus very closely approximating the condition found
in seed-bearing plants.

Bruchmann also asserts that in some species the germination does
not begin until after the spores are shed. He gives no figures of
sections of the spores, so that it is not quite clear whether or not he
implies that the spore when shed had but a single nucleus. This
seems highly improbable.

APPENDIX 641

Bruchmann also found that in some species, e.g., S. Martensii, S.
spinulosa, no diaphragm is developed, but that there is a gradual
transition from the small-celled archegonial tissue at the apex to the
larger-celled tissue of the basal region. In S. GaleoUei the cells are
arranged in concentric layers, but there is no diaphragm.

P. 518. Bruchmann's recent studies on the embryo show much
variation. In S. denticulata the first or basal wall divides the embryo
into a hypobasal and epibasal cell, as in 5. Martensii, but from the
former is developed not only the multicellular suspensor, but also the
foot and later the first rhizophore. In S. ruhricaulis the foot is also
of hypobasal origin, but the suspensor is very short.

P. 520. Bruchmann figures a prothallium of S. Kraussiana,
showing rhizoids. These are, however, much less conspicuous than
in some other species, e.g., S. GaleoUei, where there are large promi-
nences with a bunch of long rhizoids at the outer angles of the pro-
thallium. He states that rhizoids occurred in all the species examined.

S. GaleoUei shows a marked difference. A membrane is formed
about the fertilised egg, which then contracts and forms another
membrane, after which it divides into two cells. The young embryo
thus lies within a membrane, which now elongates and carries the
young embryo down into the endosperm, part of which has become
disintegrated. In a later paper (10) he states that this is also the
condition in S. Kraussiana. The elongated "suspensor," therefore,
figured in the text (Fig. 298, A. sus.) is this tube which bears within
it the young embryo shown in Fig. 298, F.

In two species, S. spinulosa and S. ruhricaulis, Bruchmann found
embryos developed parthenogenetically.

P. 524. A detailed study of the strobilus of Selaginella has been
made by Sykes (4) and Mitchell (i). From these investigations it
appears that there is a good deal of variation in several respects in
different species. The sporophyll itself may be quite simple, or it
may be provided with a dorsal flap, which acts as a protection for the
sporangium belonging to the next older sporophyll. This is especially
marked in 5. pumila (Sykes and Stiles (4), p. 524).

The distribution of the two sorts of sporangia, also, shows much
variation (Mitchell (i)). In S. spinosa, S. rupestris, S. Helvetica,
among others, are found several basal macrosporangia, followed by
numerous microsporangia. In S. atroviridis, S. gracilis, and others,
the cones are wholly macrosporangiate or microsporangiate. In
another category, e.g., S. Martensii, S. caulescens, etc., there is an
indiscriminate mingling of macrosporangia and microsporangia.
41

642 MOSSES AND FERNS

The difference in size between the two sorts of sporangia is most
marked in those where the macrosporangia are confined to the basal
portion of the cone.

P. 529. For a detailed discussion of the morphological nature of
the rhizophore see Worsdell (i).

P. 530. For Goebcl (16), read (9); for Bower (15), read (14).

P. 532. There is considerable variation in the number of mega-
spores that may be formed (Mitchell (i) ). While in most cases
there are four, the number may be reduced to two, e.g., S. rupestris, or
even a single one, e.g.j S. sulcata.

Conversely, cases have been observed where more than one mother
cell divides so that the number exceeds four. Miss Mitchell observed
twelve in a specimen of 5. Vogelii, and eight in one of S. involvens.
In 5. Helvetica Kainradt (i) found that not infrequently two spore-
tetrads were formed, and in one case four complete spore-tetrads
were seen in a macrosporangium.

CHAPTER XIV

P. 534. For Sadebeck (8), read (9).

P. 536. See Wernham's paper on Pkylloglosstmi (i), for a compari-
son of that genus with Isoetes.

P. 553. One of the recent accounts of the anatomy of Isoetes is
by Miss Stokey (i), who examined four species. Her account agrees
essentially with that of other observers. Her conclusion as to the
systematic position of Isoetes is that it should be placed in the Lycopo-
diales. Lang (14) has still more recently made an elaborate study
of the general morphology of the stock of /. lacnslris.

P. 554. The type of secondary wood in Isoetes has been compared to
that of the fossil Lepidodendreae. (See Stokey (i), p. 332.)

CHAPTER XV

P. 563. See Allen (i).

P. 569. The embryo of certain species of Ophioglossjim (e.g., O.
Moliiccaniim) probably resembles that of the ancestral Fern. It con-
sists at first simply of the large foot and the young primary leaf. At
this stage the embryo bears a marked resemblance to the young
sporophyte of Anthoceros. The root arises somewhat later, deep
down in the tissue near the junction of the leaf and foot. As this

APPENDIX 643

endogenous root develops, it penetrates the tissues of the foot and
also the overlying tissue of the gametophyte, and emerging, grows
downward into the ground.

P. 569. Tenth line from bottom; *' alteration" should read
*' alternation."

P. 570. For Scott (3), read (4).

P. 571. For Lang (3), read (2).

P. 571. A doubtful case of apogamy has been noted by Jeffrey
in Botrychium, one of the Eusporangiate Ferns. (Jeffrey (i).)

CHAPTER XVI

P. 576. Among the many contributions to a knowledge of the
fossil Archegoniates that have appeared in the last ten years, the
following may be noted :

Stopes (i), Scott (5, 6), Browne (i), Coulter (5), Kidston (i),
Seward (5), Bower (22), Chodat (i), Oliver (i), Jeffrey (4).

BIBLIOGRAPHY

Abbot, James. — Scalariform ducts in Prothalli. Quarterly Journal of

Microscopical Science, new ser., xiv: 401, 1874.
Abrams, L. R. — Structure and Development of Cryptomitrium tenerum.

Bot. Gazette, xxviii: 110-121, 1899.
Akerman, Ake. — Uber die Chemotaxis der Marchantia-spermatozoiden.

Zeitschr. f. Botanik, 11 : 94-103, 1910.
Allen, Charles E. — i. Die Keimung der Zygote bei Coleochaete. Ber.

der deutsch. bot. Gesellsch., xxiii: 285, 1905.

2. The Spermatogenesis of Polytrichum juniperinum. Ann. Bot.,
xxxi: 269-290, 191 7.
Allison, H. E. — Notes on the vascular connections of the Sporocarp of

Marsilia polycarpa. New Phytologist, x: 204-206, 191 1.
Ambronn, H. — Ueber Poren in den Aussenwanden der Epidermiszellen.

Pringsheims Jahrb. fiir wiss, Botanik, xiv: 82-109, 1884.
Andreas, J. — Ueber den Bau der Wand und die Oeffnungsweise des Le-

bermoossporogons, Flora, xxxvi : 161-213, 1899.
Andrews, W. M. — Apical growth of the roots in Marsilia quadrifolia and

Equisetum arvense. Botanical Gazette, xv: 174, 1890.
Arber, E. a. Newell. — The Past History of the Ferns. Ann. Bot.,

XX : 215-232, 1906.
Arcangeli, G. — I. Studi sul Lycopodium selago. Livorno, 1874.

2. Sulla Pilularia e Salvinia. Nuovo Giornale Botanico Italiano, viii :
320, 1876.
Archer, James. — ProthaUi with scalariform ducts. Q.J. M.S., new ser.,

XV : 106, 1875.
Arnoldi, W. — Die Entwickelung des weiblichen Vorkeims bei den hetero-

sporen Lycopodiaceen. Bot. Zeit., liv: 159-168,1896.

2. Beitrage zur Kenntniss der Keitnung von Salvinia natans. Flora,
C : 121-139, 1910.
AsHWORTH, J. H., On the Structure and Contents of the Tubers of Antho-

ceros tuberosus. Mem. and Proc. Manchester Literary and Philosophi-
cal Society, xli, No. 2, 1896.
Bancroft, N. — On the xylem elements of the Pteridophyta. Ann. Bot.,

XXV : 745-760, 1911.
Barnes, C. R. — Artificial keys to the genera and species of Mosses. Trans.

Wisconsin Acad, of Sciences, Arts and Letters, viii : 1890.

64s

646 MOSSES AND FERNS

Barnes, C. R., and Land, W. J. — 2. The origin of Air-chambers, Bot.

Gaz., xHv: 189-197, 1907. 3. The origin of the cupule of Mar-

chantia. Bot. Gaz., xlvi : 401-409, 1908.
De Bary, a. — I. Sur la germination des Lycopodes. Ann. des Sci.

naturelles, ser. 4, vol. ix : p. 30, 1858.

2. Ueber apogame Fame und die Erscheinung der Apogamie im

Allgemeinen. Bot. Zeit., 1878, p. 449.

3. Comparative Anatomy of the vegetative organs of the Phanero-

gams and Ferns. Oxford, 1884.
Bastit, E. — Comparison entre le rhizome et la tige feuillee des Mousses.

Bui. de la Soc. bot. de France, xxxvi: 295, 1889.
Bauke, H. — I. Entwickelungsgeschichte des Prothalliums bei den

Cyatheaceen. Pringsheims Jahrb. fiir wiss. Botanik, x: 49, 1876.

2. Beitrage zur Keimungsgeschichte der Schizaeacecn. Pringsh.

Jahrb. fiir wiss. Botanik, xi : 603, 1878.

3. Das Prothallium von Platycerium grande. Bot. Zeit., 1879, p. 433.

4. Einige Bemerkungen iiber das Prothallium von Salvinia natans.

Flora, Ixii : 209, 1879.

5. Aus dem botanischen Nachlass von H. Bauke. Bot. Zeit. (Beilag.),

1880.
Beck, G. — Einige Bemerkungen iiber den Vorkeim vo 1 Lycopodium.

Oesterreichische botanische Zeitschrift, 1880, p. 341.
Becquerel, p. — Germination des spores d'Atrichum undulatum et

d'Hypnum velutinum. Rev. gen. Bot. : 49-66, 1906.
Beer, R. — i. On the Development of the Spores of Riccia glauca. Ann.

Bot., XX : 293-300, 1906.

2. On the Development of the Spores of HeJminthostachys Zeylanka.

Ann. Bot., xx: 177-186, 1906.

3. The Development of the Spores of Equisetum. New Phytologist,

viii : 261-266, 1909.
Behrens, J. — Ueber die Regeneration bei den Sclagincllccn. Flora,

Erganzungsb., Ixxxiv: 159-166, 1879.
Belajeff, W. — I. Die Antheridien und Spermatozoiden der heterosporen

Lycopodineen. Bot. Zeit., 1885, p. 793.

2. Ueber Bau und Entwickclung der Spermatozoiden der Gefiisskryp-

togamen. Ber. der deutschen bot. Gcscllschaft, vii : 122, 1888.

3. Ueber Bau und Entwickclung der Spermatozoiden der Pflanzen.

Flora, Ixxix: Erganzsb., 1-48, 1894.

4. Ueber den Nebenkern in spermatogcnen Zellcn und die Sperma-

togenese bei den Farnkriiuter. Ber. der deutsch. bot. Gesell.,
XV : 337, 1897-

5. Ueber die Cilicnbildner in den spermatogcnen Zellcn. Ber. der

deutsch. bot. Gesell., xvi : 140, 1898.

6. Ueber die miinnlichcn Prothallicn der Wasserfarne (Hydropteri-

des). Bot. Zeit., Ivi: 141-19A. 1898.

BIBLIOGRAPHY 647

7. Ueber die Centrosomcn in den spermatogenen Zellen. Ber. der
deutsch. botan. Gesell., xvii : 199-205, 1899.
Benedict, R. C. — i. F>rn leaves, ferns, and fern-allies. American
Fern Journal, 1 : 1910.

2. The origin of New Varieties of Nephrolepis by orthogenetic salta-
tion. I. Progressive Variations. Bull. Torrey Bot. Club,
xliii : 207-234, 1916.
Bengt, L. — Ueber die Reizbewegungen der Marchantiaspermatozoiden.

Pringsh. Jahrb. fiir wiss. Botanik, xli : 65-87, 1,904.
Benson, Margaret J. — i. The Sporangiophore, a unit of structure in

the Pteridophytes. New Phytologist, vii: 143-149, 1908.
Berggren, S. — I. Entwickelung und Bau des Proembryo von Diphys-
cium und (Edopodium. Botaniska Notiser af Nordstedt, 1873, p. 109.

2. Om AzoUas prothallium och Embryo. Lund's Univer. Arsskrift,

vol. xvi.

3. Apogamie in Notochlaena. Botaniska Notiser, 1888. Bot. Cen-

tralblatt, xxxv: 183, 1888.
Berthold, G. — Studien iiber Protoplasmamechanik. Leipzig, 1886.
Bertrand, C. E. — I. Recherches sur les Tmesipteridees. Arch, bot, du
Nord de la France, 1882.

2. Le Type Tmesipteridee. Bull, de la Soc. bot. de France, xxx. :

p. 157, 1883.

3. Phylloglossum Drummondii. Archives botaniques du Nord de la

France, 1885, Nos. 30-33 ; also 1886, 34.

4. (and Cornaille, F.) — Les Characteristiques des Traces foliaires

Osmondeennes et Cyatheaceennes. Extr. des Proces Verbaux
de la Societe d'Histoire Naturelle d'Autun, 1902.
Bessey, C. E. — I. A Synopsis of Plant Phyla. University Studies,

vii: 99 pp., Lincoln, 1907,
Binford, R. — I. Development of the Sporangia of Lygodium. Bot.

Gaz., xliv: 214-224, 1907.
Bitter, G. — i, Marattiaceae. Engler and Prantl, Die Natiirlichen Pflan-

zenfamilien, i Th. iv Abt., 422-444, 1900.

2. Ophioglossaceae. I hid., 449-472.
Black, C. A. — i. The Morphology of Riccia Frostii. Ann. Bot., xxvii :

511-532, 1913.
Blackman, V. H. — I. Alternation of Generations and Ontogeny. New

Phytologist, viii: 207-218,1909.
Blakeslee, A. E. — I. Sexual condition in Fegatella. Bot. Gaz., xlvi:

384-385, 1908.
Blasius, W. — Ueber die americanische ''Auferstehungspflanze" (Selagi-

nella lepidophylla, Spr.). Jahresb. d. Ver. f. Naturw. zu Braunschweig,

1879, 1880. Bot. Centralblatt, ii: 966, 1880.
B olleter, Eugen. — i . Fegatella conica , eine morphologisch-physiologische

Monographie. Bot. Centrlbl. Beihefte, xviii, Abt., i: 327-408, 1905.

648 MOSSES AND FERNS

Boodle, L. A. — i. On some points in the Anatomy of the Ophioglossaceae.
Ann. of Bot., xiii : 377-394, 1899.

2. Comparative Anatomy of the Hymenophyllacea^, Schizaeaceae and

Gleicheniacea?.

I. On the Anatomy of the Hymenophyllaceae. Ann. of Bot.,
xiv: 455-496, 1900.

3. II. On the Anatomy of the Schizaeaceae. Ann. of Bot., xv : 359-

421, 1901.

4. III. On the Anatomy of the Gleicheniaceae. Ibid. : 703-747.

5. IV. Further Observations on Schizaea. Ann. of Bot., xvii : 511-

537, 1903-

6. Secondary tracheids in Psilotum. Ann. of Bot., xviii : 505-517,

1904.

7. The MonoccisTn of Funaria hygrometrica. Ann. Bot., xx: 321,

1906.

8. On the production of dwarf male ProthaHi in the sporangia of

Todea. Ann. Bot., xxii: 231-243, 1908.
Bower, F. O. — i. Note on the gemmae of Aulac omnium paluslre. Journal
of Lin, Soc, XX : 465, 1884.

2. Comparative Morphology of the leaf of the Vascular Cryptogams

and Gymnosperms. Proc. of the Roy. Soc, xxxvii : 61, 1884.
Phil. Trans., clxxv : 565, 1884.

3. Preliminary note on the apex of the root and leaf in Osmtinda and

Todea, Proc. Roy. Soc, xxxvi : 442, 1884.

4. Apex of the root in Osmunda and Todea. Q. J. Mic Sci., new

ser., XXV : 75, 1885.

5. Phylloglossum Drummondii. Royal Soc. Phil. Transactions,

clxxvi : Part II, 665, 1885.

6. Apospory and allied phenomena. Trans, of the Linnaean Soc.

Second ser., Bot., vol. ii : 301, 1887.

7. Preliminary note on the formation of gemmae in Trichomanes ala-

tum. Ann. of Botany, i: 183, 1887.

8. On some normal and abnormal developments of the Oophyte in

Trichomanes. Ann. of Botany, i: 269, 1888.

9. Antithetic as distinct from homologous alternation of generations

in plants. Annals of Botany, iv : 347, 1890.

10. Attempts to induce aposporous development in Ferns. Annals

of Botany, iv : 168, 1889.

11. The comparative examination of the IMeristems of Ferns as a

phylogenetic study. Annals of Botany, iii : 305, 1889.

12. Is the Eusporangiate or the Leptosporangiate the more primitive

type of Fern? Annals of Botany, vol. v : 109, 1891.

13. On the structure of Lcpidostrobus Brownii Sch. Annals of Botany,

vii: 329, 1893.

14. Studies in the IVIorphology of the spore-producing members.

BIBLIOGRAPHY 649

Equisetineae and Lycopodineae. Roy. Soc. Phil. Trans., vol.
clxxxv: 1894, 473.

15. A Theory of the Strobilus in Archegoniate Plants. Ann. of Bot.,

viii: 343, 1894.

16. Studies in the Morphology of Spore-producing Members, ii :

Ophioglossacea^, London, 1896.

17. Studies in the Morphology of Spore-producing Members, iii:

Marattiaceae. Phil. Trans. Roy. Soc, series B, vol. 189 : 35-81,
1897.

18. Address before Section K, British Association, Bristol, 1898. Na-

ture, lix : 66-88-112,1898.

19. Studies in the Morphology of Spore-producing Members, iv.

The Leptosporangiate Ferns. Phil. Trans., ser. B, vol. 192 : 29-
138, 1899.

20. Studies in the Morphology of Spore-producing Members, v.

General Comparisons and Conclusions. Phil. Trans., ser. B,
vol. 196: 191-257, 1903.

21. Ophioglossum simplex^ Ridley. Ann. of Bot., xviii : 205, 1904.

22. The Origin of a Land Flora, London, 1908.

23. Studies in the Phylogeny of the Filicales. i. Plagiogyria.

Ann. Bot., xxiv: 423-450, 1910.

24. Notes on the Morphology of Ophioglossum pahnatum. Ann. Bot.,

XXV : 277-298, 1911.

25. On the primary xylem and the origin of medullation in the Ophio-

glossaceae. Ann. Bot., xxv: 537-553, 1911.

26. On Medullation in the Pteridophyta. Ann. Bot., xxv: 555-

574, 1911.

27. Studies in the Phylogeny of the Filicales, ii. Lophosoria, and

its relation to the Cyatheoideae. Ann, Bot., xxvi: 269-
324, 1912.

28. Studies in the Phylogeny of the Filicales, iii. On Metaxya

and certain other relatively primitive ferns. Ann. Bot.,

xxvii: 443-477, 1913-

29. Studies in the Phylogeny of the Filicales, iv. Blechnum and

allied genera. Ann. Bot., :^xviii : 363-431, 1914.

30. Studies in the Phylogeny of the Filicales, v. Ann. Bot., xxix:

495-529, 1915-

31. Studies in the Phylogeny of the Filicales, vi. Ann. Bot., xxxi :

1-39, 1917.
Brebner, G. — I. On the Mucilage-canals of the Marattiaceae. Journ.
Lin. Soc, London, xxx : 444, 1895.
'2. On the Prothallus and Embryo of Dancea simplicifolia, Rudge.

Ann. of Bot., x: 109, 1896.
3. On the Anatomy of Danaea and other Marattiaceae. Ann. of Bot.,
xvi: 517-552, 1902.

650

MOSSES AND FERNS

Breeves, J. — On the development of the stem and leaves of Physiotium

gigantciim. Trimen's Journal of Botany, xxxii: t,^,, 1894.
Brixton, E. G., and Taylor, A. — i. The Life History of Schizaa pusilla.
Contributions from the N. Y. Bot. Garden, No. 11, 1901. Also Bull.
Torrey Bot. Club, xxviii : 1-19, 1901.
2. The Life History of Vittaria lineata. IVlem. Torrey Bot. Club,
viii: No. 3, 1902.
Brotherus, V. F. — Bryales. Engler and Prantl, Die Nat. Pllanzenf.

Theil i, Ab. 3: 288-1171+, 1902-1909.
Browne, Isabel. — i. The Phylogeny and Interrelationships of the
Pteridophyta. New Phytologist, vii, viii: 1908-1909.

2. A second contribution to our knowledge of the Anatomy of the

Cone and fertile stem of Equisetum. Ann. Bot., xxix: 231-
264, 1915.
Bruchmann, H. — I. Wurzeln von Isoetes und Lycopodium. Jenaische
Zeitschrift fiir Naturwissenschaften, 1874.

Die vegetativen Verhaltnisse der SelagineUeen. Giebel's Zeit-
schrift fiir die gesammten Naturwissenschaften, 1877.

3. Untersuchungen liber Selaginella spinulosa, A. Br. Gotha, 1897.

4. Ueber die Prothallien und die Keimpflanzen mehrerer Euro-
paischer Lycopodien. Gotha, 1898.

Ueber das Prothallium und die Keimpflanze von Ophioglossum vul-

gatum L. Bot. Zeit., Ixii : 227-247, 1904.
Uber das ProthalUum und die Sporenpflanze von Botrychium

Lunaria. Flora, xcvi : 203-230, 1906.
Das Prothallium von Lycopodium complanatum. Bot. Zeit.,
Ixvi : 1 69-181, 1908.
8. Vom Prothallium der grossen Spore und der Keimesentwickelung
einiger Selaginella-Arten. Flora, xcviii : 12-51, 1908.
Die Keimung der Sporen und die Entwickelung der Prothallien
von Lycopodium clavatum, L. annotinum und L. Selago.
Flora, ci : 220-267, 1910.
10. Zur Reduction des Embryotragers bei Selaginella. Flora, civ :
237-246, 1913.
Bryan, G. S. — The Archegonium of Sphagnum. Bot. Gaz., lix: 40-

56, 1915-

2. The Archegonium of Cathcrinea angustafa Brid. {Atrkhiim
angustatmn). Bot. Gaz., Ixiv : 1-20, 1917.
BucH, H. — 7. Uber die Brutorgane der Lebermoose. Helsingfors, 191 1.
BucHTiEX, O. — Entwickelungsgeschichte des Prothallium von Equisetum.

Bibliothcca botanica, vol. viii., Cassel, 1887.
BuLLER, A. H. R. — Contributions to our Knowledge of the Physiology of

the Spermatozoa of Ferns. Ann. of Bot., xiv : 543, 1900.
BuENGER, E. — Beitrage zur Anatomic der Laubmooskapsel. Botanisches

Centralblatt, vol. xHi., 1890, p. 193.

BIBLIOGRAPHY 651

BuESGEN, M. — Untersuchungcn iiber normale und abnormale Marsilien-

friichten. Flora, Ixxiii : 169,1890.

BuRCK, W. — I. Das Prolhallium von Aneimia. Bot. Zeit., 1875, p. 499-

2. Sur la devcloppement du prothalle d' Aneimia compare a celui des

autres fougeres. Archives Neerlandaises des Sciences exactes

et naturelles, t. x: 417, 1875.

BuRLiNGAME, L. L. —The Sporangium of the Ophioglossales. Bot. Gaz.,

Ixiv: 34-56, 1907-
Ca^ipbell, D. H. — I. The structure and development of the Ostrich
Fern. Mem. Boston Soc'ety of Natural History, 1887.

2. Zur Entwickelungsgeschichte der Spermatozoiden. Berichte der

deutsch. bot. Gesellschaft, vi: 120, 1887.

3. The development of Pilidaria glohulifera L. Annals of Botany,

ii : 233, 1888.

4. Einige Notizen uber die Keimung von Marsilia ^gyptiaca. Ber.

der deutsch. bot. Gesellschaft, v: 340, 1888.

5. The systematic position of the Rhizocarpeae. Bulletin of the

Torrey Bot. Club, xv: 258, 1888.

6. A study of the apical growth of the prothallium of Ferns. Ibid.,

xviii: 73, 1891.

7. On the affinities of the Filicineae. Bot. Gazette, xv: i,

1890.

8. Die ersten Keimungsstadien der Macrospore von Isoetes echino-

spora Durieu. Berichte der deutsch. bot. Gesellschaft, viii :
97, 1890.

9. Notes on the apical growth in the roots of Osmunda and Botryr

chium. Botanical Gazette, xvi : 37, 189 1.

10. Contributions to the Life History of Isoetes. Annals of Botany,

v: 231, 1891.

11. On the relationships of the Archegoniatae. Botanical Gazette,

xvi: 323, 1891.

12. On the Prothallium and Embryo of Osmunda Claytoniana L. and

O. Cinnamomea L. Annals of Botany, vi : 49, 1892.

13. On the Prothallium and Embryo of Marsilia vestita. Proceed-

ings of the California Acad, of Sciences, 2nd Ser. vol. iii: 183,
April, 1892.

14. The development of the sporocarp of Pilidaria Americana. Bui.

Torrey Bot. Club, xx: 141, 1893.

15. On the development of Azolla filiculoides, Lam. Annals of

Botany, vii : 155, 1893.

16. Observations on the development of Marattia Douglasii, Baker.

Annals of Botany, viii : i, 1894.

17. Notes on Sphaerocarpus. Erythea, iv: 73,1896.

18. The Development of Geothallus tuberosus, Campbell. Ann. of

Bot., ix: 489, 1896.

652 MOSSES AND FERNS

19. The systematic position of the Genus Monoclea. Bot. Gaz., xxv :

272, 1898.

20. On the Structure and Development of Dendroceros, Nees. Jour.

Linn. Soc, London, xxxiii : 467, 1898.

21. Recent work upon the Development of the Archegonium. Bot.

Gaz., xxvi: 428-431,1898.

22. Studies on the Gametophyte of Selaginella. Ann. of Bot., xvi :

419-428, 1902.

23. The Origin of Terrestrial Plants. Proc. A. A. A. S., lii : 463-484,

1903.

24. Antithetic versus Homologous Alternation. American Naturahst,

xxxvii: 153, 1903.

25. Resistance of Drought by Liverworts. Torreya, iv : 81-86, 1904.

26. Affinities of the Ophioglossaceae and MarsiHaceae. Am. Nat-

uralist, xxxviii : 761-775,1904.

27. Aflfmities of the Genus Equisetum. Am. Naturalist, xxxix:

273-285, 1905.

28. Studies on the Ophioglossaceae. Am. Naturalist, xli : 139-159,

1907.

29. Studies on the Ophioglossaceae. Ann. du Jardin Bot. de Buiten-

zorg, 2d Ser., vi : 138-194, 1907.

30. Studies on some Javanese Anthocerotaceae.

I. Ann. Bot., xxi: 467-486, 1907.
II. Ann. Bot., xxii : 91-102, 1908.

31. Symbiosis in Fern ProthaUia. Am. Naturalist, xlii: 154-165,1908.

32. The Prothallium of Kaulfussia and Gleichenia. Ann. du Jardin

Bot. de Buitenzorg, 2d Ser., viii: 69-102, 1908.

33. The Eusporangiatae ; the Comparative Morphology of the Ophio-

glossaceae and Marattiaceae. Carnegie Institution of Wash-
ington, Publication No. 141, pp. vi.-224, 191 1.

34. The Morphology and Systematic Position of Calycularia radi-

cidosa (Steph.). Dudley I^Iemorial Volume. Stanford Uni-
versity: 33-61, 1913.

35. The Genus Macroglossum Copeland. Philippine Joum. Sci.

ix. No. 3. Sec, Bot.: 219-223, 1914-

36. The Structure and affinities of Macroglossum AlidcB Copeland.

Ann. Bot., xxviii : 651-669, 1914.

37. (and Williams, Florence). — A Morphological Study of some

members of the Genus Pallavicinia. Stanford University Press:

44, pp. 1914.

38. Die Verbreitung gewisser Lebermoose der Malaischen Region.

Pfeffer Festschrift. Jahrbiicher fiir wissenschaftliche Botanik,

Ivi: 365-373, 1915-

39. The Morphology and systematic Position of Podomitrium. Am.

Journ. Bot., v: 199-210, 1915.

BIBLIOGRAPHY 653

40. The Archegonium and Sporophyte of Treuhia insignis, Goebel.
Am. Journ. Bot., vi : 261-273, 1916.
Cardiff, I. D. — The Development of the Sporangium in Botrychium.

Bot. Gaz. xxxix: 340-347, 1905.
Cavers, F.— I. Explosive discharge of Antherozoids in Fegatella conica.

Annals of Botany, xvii: 270-274, 1903.

2. On Saprophytism and Mycorrhiza in Hepaticae. New Phytologist,

ii: 30-35, 1903.

3. Some points on the biology of Hepaticae. " The Naturalist " : 1-15,

May, June, 1903.

4. Notes on Yorkshire Bryophytes, i. Petalophyllum Raljsii. "The

Naturalist": 327-334, Sept., 1903.

5. Notes on Yorkshire Bryophytes, ii. Pallavicinia Flotowiana. "The

Naturalist": Nov., Dec, 1903.

6. On the Structure and Biology of Fegatella conica. Annals of

Botany, xviii : 87-120, 1904.

7. Contributions to the Biology of the Hepaticae. Part I. Targionia,

Rehoulia, Preissia, Monoclea. Leeds and London, March, 1904.

8. Notes on Yorkshire Bryophytes, iii. Reboulia hemispherica.

"The Naturalist" : 1-15, July, Aug., 1904.

9. The Interrelationships of the Bryophyta. Reprint No. 4, New

Phytologist: pp. 203, 191 1.

Celakovsky, L. — Untersuchungen iiber die Homologien der generativen
Produkte der Fruchtblatter bei den Phanerogamen und Gefasskrypto-
gamen. Pringsheims Jahrb. fiir wiss. Botanik, xiv: 291, 1884.

Chamberlain, C. J. (see also "Coulter") — i. Winter Characters of
certain Sporangia. Bot. Gaz., xxv: 124-128, 1898.

2. Mitosis in Pellia. Bot. Gaz., xxxvi : 28-51,1903.

3. Prothallia and Sporelings of three New Zealand species of Lycopo-

dium. Bot. Gaz., Ixiii : 51-65, 1917.
Chandler, S. E. — i. On the Arrangement of the Vascular Strands in

the "Seedlings" of certain Leptosporangiate Ferns. Ann. Bot., xix :

365-410, 1905.
Charles, Grace M. — The Anatomy of the Sporeling of Marattia alata.

Bot. Gaz., 21 : 81-101, 1911.
Chodat, R. — Les Pteropsides des temps paleozoiques. Arch, des Sciences

physiques et naturelles, xxv: 44 pp., Geneva, 1908.
Christ, H. — Die Farnkrauter der Erde. Jena, 1897.

(and Giesenhagen, K.) — Pteridographische Notizen. Flora, Ixxxvi :
72-85, 1899.
Christensen, C. — Index Fihcum, Copenhagen, 1906.
Chrysler, M. A. — i. The nature of the fertile spike in the Ophioglos-

saceae. Ann. Bot., xxiv : 1-18, 1910.

2. Is Ophioglossiim palmatum anomalous? Bot. Gaz., Hi: i5i-i53)
1910.

654 MOSSES AND FERNS

Clapp, G. L. — The life history of Ancura pinguis. Bot. Gaz., Hv : 177-

193, 1912.
CoKER, W. C. — On the occurrence of two egg cells in the Arch-

egonium of Mnium. Bot. Gaz., xxxv : 136, 1903. The nucleus of

the spore cavity in Prothallia of JMarsilia. Bot. Gaz., xxxv: 137,

1903.

2. Selected Notes, ii. Liverworts. Bot. Gaz,, xxxvi: 225, 1903.
CoMPTON, R. H. — The anatomy of Matouia sarmcntosa. New Phytol-

ogist, viii: 299-307,1909.
CoNARD, H. S. — The Structure and life history of the Hay-scented Fern.

Carnegie Inst, of Wash. Publ. No. 94: Wash., 1908.
CoPELAND, E. B. — Ferns of the IMalay Asiatic Region. Philippine Jour.

Science, Sec. C. Bot., iv. 1909.
CoRAiACK, B. G. — On a cambial development in Equisetum. Annals of

Botany, vii : 63, 1893.
CoRNU, M. — Note on two-celled male prothallia of Ncphrodiiim filix-mas.

Bull, de la Soc. bot. de France, t. xxi : 161, 1874.
Coulter, J. M. — i. The Origin of the Gymnosperms and the Seed Habit.

Bot. Gaz., xxvi : 153-168, 1898.

2. The Origin of the Leafy Sporophyte. Bot. Gaz., xxviii : 46-59,

1899.

3. (and Chamberlain, C. J.) — Morphology of Spermatophytes,

Part I, Gymnosperms, New York, 1901.

4. Morphology of Spermatophytes, Part II, Angiosperms, New York,

1903.

5. (and Chamberlain, J, C.) — IMorphology of Gymnosperms :

Chicago, 1910.
Cramer, C. — i. Ueber Lycopodium Sclago. Pflanzenphysiologische
Untersuchungcn von Carl Nageli und Carl Cramer, vol. iii : p. 10.
2. Vorliiulige Mittheilung liber geschlechlloses Fortpllanzen des Farn-
prothalliums, namentlich mittels Conidien resp. Gemmen. Bot.
Centralb., Bd. i : 476, 1880.
Cutting, E. M. — On androgynous receptacles in Marchantia. Ann. Bot.,

xxiv: 349-357, iQio-
CzAPEK, F. — Zur Chemie der Zellmembranen bei den Laub- und Leber-

mooscn. Flora, Ixxxvi : 361-381,1899.
Dachnowski, a. — Zur Kenntniss der Entwickelungsphysiologie von

Marchantia polymorpha. Jahrb. der Wissenschftl. Botanik, xliv:

254-286, 1907.
Dangeard, p. a. — Essai sur I'anatomie des cryptogames vasculaires. Le

Botaniste, first series, 1889, p. 211

2. Memoire sur la morphologic et I'anatomie des Tmesipteris. Le

Botaniste, second series, p. 163, 1891.
Davenport, G. E. — Vernation in Botrychium. Bulletin of the Torrey

Botanical Club, viii: 100, 1881.

BIBLIOGRAPHY 655

Davis, B. M. — i. The Sporc-mothcr-cell of Anthoceros. Bot. Gaz.,
xxviii: 89-108,1899.

2. Nuclear Studies on Pellia. Ann. of Bot., xv: 147-180, 1901.

3. The Origin of the Archegonium. Ann. of Bot., xvii : 477-492, 1903.
Davis, R. C. — The Structure and Affinities of Peranema and Diacalpe.

Ann. Bot., xxvi: 245-268, 1912.
Deutsch, H. A. — A Study of Targionia hypophylla. Bot. Gaz., Hii :

492-503, 1912.
De Vriese, W. H., and Harting, P. — Monographie des Marattiacees,

1853.
DiELS, L. — Cyatheaceae, Polypodiaceae. Engler and Prantl, Die Nat.

Pflanzenfamihen, Th. I, Abt. iv: 112-336, 1899.

2. Polypodiaceae, Parkeriaceae, Matoniaceae, Gleicheniaceae, Schizae-
aceae, Osmundaceae. Ibid., 337-380, 1900.
DouiN, Ch. — I. Nouvelles observations sur Sphaerocarpus. Rev. Bryol.,

xxxvi : 37-41, 1909.

2. Le pedicelle de la capsule des Hepatiques. Bull. Soc. Bot. de
France, Iv: 194-202; 270-277,1908.
Druery, C. T. — I. Observations on a Singular Mode of Development in

the Lady-fern {Athyrium Filix-Joemina). Jour. Linn. Soc. Lond.

Botany, xxi: 354-358, 1884.

2. On a new instance of Apospory in Polystichum angular e var. pulcher-

rimiim. Ibid., xxii: 437-440,1887.

3. Notes on an Aposporous Lastrcea (Nephrodium). Ibid., xxix : 479-

482, 1893.

4. Notes upon Apospory in a Form of Scolopeiidrium vidgare, var;

crispum, and a new Aposporous Athyrium', also an additional
phase of Aposporous Development in Lastrcea pseudo-mas , var.
cristata. Ibid.,xxx: 281-284,1894.
DuRAND, E. J. — The development of the sexual organs and Sporogonium

of Marchantia polymorpha. Bull. Torrey Bot. Club, xxxv: 321-335,

1908.
DuTAiLLY, G. — Sur I'interpretation des differentes parties de I'embryon de

Salvinia. Comptes rendues des seances de la Soc. botanique de Lyon,

1881.
Duval- JouvE, J. — Histoire naturelle des Equisetum de France. Paris,

1864.
Fames, A. J. — On the occurrence of centripetal Xylem in Equisetum.

Ann. Bot., xxiii : 587-612, 1909.
Eaton, D. C. — Ferns of North America. Coloured plates by J. H.

Emerton and C. E. Faxon.
Ekstrakd, E. V. — Brutknospenbildung bei den foliosen Lebermoose.

Botaniska Notiser af Nordstedt, 1879, No. 2.
Ernst, A. — i. Uber androgyne Inflorescenzen bei Dumortiera. Ber.

Deutsch. bot. Gesellsch., xxv: 455-464, 1906.

656 MOSSES AND FERNS

2. Untersuchungen iiber Entwickelung Bau und Verteilung der In-
floresccnzen von Dumortiera. Ann. Jard. Bot. Buitenzorg,
ser. 2, vii: 153-223, 1908.
Evans, A. W. — i. A provisional list of the Hepaticae of the Hawaiian

Islands. Trans. Conn. Acad., viii : 253, 1891.

2. An arrangement of the genera of the Hepaticaj. Ibid., p. 262,

1892.

3. Vegetative reproduction in Metzgeria. Ann. Bot., xxiv: 271-

303, 1910.

4. Branching in the Leafy Hepaticae. Ann. Bot., xxvi: 1-37,

1912.

5. (and Hooker, H. D. Jr.) — Development of the Peristome in

Ccratodon piirpurcus. Bull. Torrey Bot. Club, xl : 97-109,

1913-
Famintzin, a. — Knospenbildung bei Equisetum. Melanges biologiques

tires du bulletin de I'Academie imperiale de St. Petersbourg, t. ix :

573, 1876.
Fankhauser, J. — Ueber den Vorkeim von Lycopodium. Bot. Zeit., 1873,

p. I.
Farlow, W. G. — I. Ueber ungeschlechthche Erzeugung von Keimpflan-

zen auf Farnprothallien. Bot. Zeit., 1874, p. 180; also Quarterly

Journal of Mic. Science, new ser., xiv: p. 266, 1874.
2. Apospory in Pteris aquilina. Annals of Botany, ii : 383, 1889.
Farmer, J. Bretland. — i. On Isoetes lacustris. Proc. Royal Soc,

vol. xlv : p. 306, 1889.

2. On Isoetes lacustris. Annals of Botany, v : 37,1890.

3. The Embryogeny of Angiopteris evecta, Hoffm. Ann. of Botany,

vi: 1892, 265.

4. Studies in Hepaticas. On Pallavicinia decipiens, Mitten. Ann. of

Botany, viii: 35, 1894.

5. (and Reeves, J.) — On the occurrence of Centrospheres in

Pellia epiphylla, Nees. Ann. of Botany, viii: 219-224,
1894.

6. On Spore-formation and Nuclear Division in the Hepaticae. Ann.

of Bot., ix: 469-523, 1895-

7. Spore-formation in Fegatclla conica. Ann. of Bot., ix : 666-668,

1895.

8. The Quadripolar Spindle in the Spore Mother-cell of Pellia epi-

phylla. Ann. of Bot., xv : 431, 1901.

9. (and Hill, T. G.) — On the Arrangement and Structure of the

Vascular Strands in Angiopteris evecta and some other Marat-
tiaceae. Ann. of Bot., xvi : 371-402, 1902.
10. (with Moore, J. E. S., and Digby, L.) — On the Cytology of
Apogamy and Apospory, i. Preliminary note on Apogamy.
Proc. Roy. Soc, Ixxi : 453-457, 1903.

BIBLIOGRAPHY 657

11. Sporogenesis in Pallavicinia. Bot. Gaz., xli : 67-70, 1906.

12. Studies in Apospory and Apogamy in Ferns. Ann. Bot., xxi:

161-199, 1907.
Faull, J. H. — The Anatomy of the Osmundaceae. Bot. Gaz., xxxii : 381-

420, 1901.

2. The Stele of Osmunda cinnamomea. Trans. Canadian Instit.,
vii: 515-534, 1910-
Fellner, Ferd. — Ueber die Keimung der Sporen von Riccia glauca.

Jabresber, der Akad. des naturwiss. Ve reins in Graz, 1875.
FiRTSCH, G. — Ueber einige mechanische Einrichtungen in anatomischen

Bau von Polytrichum juniperinum. Berichte der deutschen botan-

ischen Gesellschaft, i: ^2)i 1883.
Fitting, H. — i. Bau und Entwickelungsgeschichte der Macrosporen von

Isoetes und Selaginella, und ihre Bedeutung fiir die Kenntniss des

Wachstums pflanzHcher Zehmembranen. Bot. Zeit., Iviii : 107-165,

1900.
Ford, Miss S. O. — i. The Anatomy of Ceratopteris thalictroides. Ann.

of Bot., xvi : 95-120, 1902.
Garber, J. F. — The Life History of Ricciocarpus natans. Bot. Gaz.,

xxxvii : 161-177, 1904.
Gardner, W., and Tokutaro, Ito. — On the structure of the mucilage-se-
creting cell of Blechniim occidentale, L., and Osmunda regalis, L. Ann.

of Botany, i : 27, August, 1887.
Gar JEANNE, A. J. M. — i. Die Oelkorper der Jungermanniales. Flora,

xcii: 457-482, 1903.
Gayet, L. a. — Recherches sur le developpement de I'archegone chez les

Muscinees. Ann. des Science naturelles, Bot., ser. 8, 3 : 161-258,

1897.
Georgevitch, p. — Preliminary note on Apospory and Apogamy in

Trichomanes Kaulfussii. Ann. Bot., xxiv: 233-234,1910.
Gerard, R. — Recherches sur le passage de la racine a la tige. Ann. des

Sciences naturelles, sixth series, xi : 279, 1881.
Gibson, R. J. Harvey. — i. On the silicious deposit in certain species of

Selaginella. Ann. Bot., vii : 355,1893.

2. Contributions towards a knowledge of the anatomy of the genus

Selaginella. Ibid.,Y\\\: 13^3,1894.

3. Note on the diagnostic characters of the subgenera and species of

Selaginella, Spr. Transactions Biol. Soc. Liverpool, vol. viii.,
1894.

4. Contributions toward a Knowledge of the Anatomy of the Genus

Selaginella, i. The Stem. Ann. of Bot., viii: 355, 1904.

5. The Anatomy of Selaginella, ii. The Ligule. Ann. of Bot., x:

76-88, 1896.

6. The Anatomy of Selaginella, iii. The Leaf. Ann. of Bot., xi:

123-155, 1897.
42

658 MOSSES AND FERNS

GiESENHAGEN, C. — (See also Christ.) — Die Hymenophyllaceen. Flora,

Ixxiii: 411, 1890.
GiLTAY, E. — Ueber eine cigenthiimliche Form des Stereoms bei gewissen

Fame. Bot. Zeit., 1882, p. 694.
Glueck, G. — Die Sporophyllmelamorphose. Flora, Ixxx: 303-387,

1895.
GoEBELER, E. — Die Schutzvorrichlungen am Stammscheitel der Fame.

Flora, biix : 451, 1886.
GoEBEL, K, — I, Das Prothallium von Gymnogramme Icptophylla. Bot.

Zeit., 1877, p. 671.

2. Wachsthum von Metzgeria mid Ancura. Arbeiten des bot. Insti-

tuts, Wiirzburg, ii : 285, 1879.

3. Beitriige zur vergleichcndcn Entwickelungsgeschichtc der Sporan-

gien. Bot. Zeit., 18S0, p. 545, 1881, p. 681.

4. Zur Embryologie der Archegoniaten. Arbeiten des bot. Instituts

in Wiirzburg, ii : 437, 1880.

5. Zur vergleichenden Anatomie der Marchantiaceen. Ibid., p. 529.

6. Beitrage zur vergleichenden Entwickelungsgeschichtc der Sporan-

gicn. Pilularia globulifera. Bot. Zeit., 1882, p. 771.

7. Ueber die Antheridienstande von Polytrichum. Flora, Ixv: ^2^,

1882.

8. Die Muscineen. Schenks Handbuch der Botanik, vol. ii., 1882.

9. Vergleichende Entwickelungsgeschichtc der Pflanzenorgane.

Schenks Handbuch der Botanik, vol. iii., 1884.

10. Das Prothallium von Lycopodium inundatum. Bot. Zeit., 1887,

p. 161.

11. Morphologische und biologische Studien, i, 11. Annales du

Jardin botanique de Buitenzorg, vii : 1-119, 1887.

12. Outlines of Classification and special Morphology. (Translation

of the German Edition.) Oxford, Clarendon Press, 1887.

13. Ueber die Fruchtsprosse der Equiseten. Ber. d. deutsch. bot.

Gesell., iv: 184, 1886.

14. Ueber die Jugendstande der Pflanzcn. Flora, Ixxii : i, 1889.

15. Morphologische und biologische Studien, iv. Ann. du Jardin bo-

tanique de Buitenzorg, ix : 1-40, 1891.

16. Archegoniatenstudien. Flora, Erganzungsband, 1892, Bd. Ixxvi :

92. Also Flora, Bd. Ixxvii : S2, 1893.

17. On the simplest form of Moss. Ann. of Botany, vol. vi : 355,

1892.

18. Ueber Function und Anlcgung der Lebermooselateren. Flora,

Ixxx: 1-37, 1895.

19. Ueber die Sporenausstreuung bei den Laubmoosen. Flora, Ixxx:

459-486, 1895.

20. Hecistopteris, eine verkannte Farngattung Flora, Ixxxii : 67-

75, 1896.

BIBLIOGRAPHY 659

21. Organographie der Pflanzen. Four Parts. Jena, 1898-1901.

2d Edit., 1913-15.

22. Sporangien, Sporenverbreitung und Blutenbildung bei Selaginella.

Flora, Ixxxviii : 207-228,1901.

23. Ueber Homologien in dcr Entwickelung mannlicher und wcib-

licher Geschlechtsorgane. Flora, xc : 279-305,1902.

24. Archegoniatenstudien, x. Beitrage zur Kenntniss australischer

und neuseeliindischer Bryophytcn. Flora, xcvi: 95-202, 1906.

25. Archegoniatenstudien, xi. Weitcre Untersuchungen liber Kei-

mung und Regeneration von Riella und Sphaerocarpus. Flora,
xcvii: 192-215, 1907.

26. Archegoniatenstudien, xii. Uber die Brutknospenbildung und

iiber die systematische Stellung von Riella. Flora, xcviii :
308-323, 1908.

27. Archegoniatenstudien, xiii. Flora: 43~97> 1910-

28. Archegoniatenstudien, xv. Die Homologie der Antheridien und

Archegonien bei den Lebermoosen. Flora, cv: 53-70, 1913.
GoLENKiN, ]\I. — Die JMycorhizaahnlichen Bildungen der Marchantiaceen.

Flora, xc : 209-220, 1902.
Gordon, W. T., On the Prothallus of LepUodcndron Veltheimianiim.

Trans. Bot. Soc. Edinb., xxiii, 1908.
GoTTSCHE, C. M. — I. Anatomisch-physiologische Untersuchungen iiber

Haplomitrium Hookeri. Acta Acad. Caes. Leopold. Car. Nat. Cur.,

t. XX, pars i, p. 267, 1841.

2. Uebersicht und kritische Wiirdigung der Leistungen in der Hepat-
icologie. Bot. Zeit. (Supplement), 1858, p. 49.
Graham, Margaret. — The development of the Sporogonium and adjacent

tissues of the Gametophyte of Conocephalum conicum. Bull. Torrey

Bot. Club., xxxvi: 615-623, 1909.
Groenland. — Memoire sur la germination de quelques Hepatiques. Ann.

des Sci. nat., series iv., t. 1:5, 1854.
GuiGNARD, Leon. — i. Developpement et constitution des antherozoides.

Revue generale de botanique, 1889, t. i. liv. 1-4.

2. Sur les antherozoides des Marsihacees et Equisetacees. Bui. de la

Soc. bot. de France, xxxvi: 378, 1889.

3. Sur la constitution du noyau sexuel chez les vegetaux. Comptes

rendus, Paris, t. cxii: 1074, 1891.
G WYNNE- Vaughn, D. T. — i. Observations on the Anatomy of Soleno-
stelic Ferns, I. Loxsoma. Ann. of Bot., xv: 71-98, 1901-

2. Observations on the Anatomy of Solenostelic Ferns, Part II.

Ann. of Bot., xvii: 689-742, 1903.

3. On the real nature of the tracheae of Ferns. Ann. Bot., xxii : 401-

413, 1908. (See also Kidston.)

4. On the Anatomy of Archangiopteris Henryi and other Marattiaceae.

Ann. Bot., xix: 259-271, 1905.

66o MOSSES AND FERNS

Haberlandt, G. — I. Vergleichende Anatomic des assimilatorischen
Gewebesystems der Pflanzen. Pringsheims Jahrb. fur wiss. Bot.,
xiii: 74, 1882.

2. Ueber die physiologische Function des Centralstranges im Laub-

moosstammchens. Ber. der deutschen bot. Gescllschaft, i :
263, 1883.

3. Ueber Wasserleitung im Laubmoosstammchen. Ibid., ii : 467,

1884.

4. Beitrage zur Anatomic und Physiologic der Laubmoosen. Prings-

heims Jahrb. fiir wiss. Botanik, xvii : 359, 1886.

5. Das Assimiiationssystem der Laubmoosen. Flora, Ixi.x: 45,

1886.

6. Ueber Collateralc Gefassbiindcl im Laube der Fame. Sitzb. der

k. Akad. der Wiss. Wien, Ixxxiv., i Abt., p. 121, 1881.

7. Ueber das Assimiiationssystem. Ber. der deutschen bot. Gescll-

schaft, iv: 206, 1886.

8. Zur Kenntniss des Spaltoffnungsapparat. Flora, Ixx: 97,1887.

9. Die Chlorophyllkorper der SclagincUeen. Flora, Ixxi : 291, 1888.
Halft, F. — Die SchHcsshaut der Hoftupfel im Xylem der Gefasskrypto-

gamen. Inaug. Dissert., 31 pp., Bonn, 1910.
Hannig, E. — Ueber die Staubgriibchen an den Stammen und Blattsticlen

der Cyatheaceen und Marattiaceen. Bot. Zcit., Ivi : 9-33, 1898.
Hansel, V. — i. Keimung von Preissia commutata. Sitzungsberichtc der

kais. Akademie der Wissenschaften, Wien, Ixxiii, i Abthcilung:

89, 1876.
Hanstein, J. — I. Pilulariai globulifcrae generatio cum Marsilia com-

parata. Bonn, 1866.

2. Befruchtung und Entwickelung der Gattung Marsilia. Prings-
heims Jahrbiicher fiir wiss. Botanik, iv: 197, 1865.
Hawkins, L. A. — The Development of the Sporangium of Equisctum

hiemale. Ohio Naturalist, vii : 122-126, 1907.
Haynes, Caroline C. — Sphaerocarpos hians, Sp. Nov., with a revision

of the Genus — and illustrations of the Species. Bull. Torrey Bot.

Club, xxxvii : 215-230, 1910.
Heald, F. D. — I. Conditions for the Germination of the Spores of Bryo-

phytes and Pteridophytcs. Bot. Gaz., xxvi: 25-45, 1898.

2. A Study of Regeneration as exhibited by Mosses. Ibid., 169-210,
1898.
Hegelmaier. — Zur Morphologic der Gattung Lycopodium. Bot. Zeit.,

1872, 773.
Heim, Carl. — Untersuchungen iibcr Farnprothallien. Flora, Ixxxii :

329-386, 1896.
Heixricher, E. — I. Die jiingsten Stadien der Adventivknospen an der
Wedelspreite von Asplenium bulbiferum. Sitzber. der kais. Akad. der
Wissenschaften, Wien, Ixxxiv, i Abt.: 115, 1881.

BIBLIOGRAPHY 66i

2. Die naheren Vorgiinge bei der Sporcnbildung der Salvinia natans
verglichen der iibrigcn Rhizocarpeen. Sitzber. der k. Akad. der
Wiss., Wien, Ixxxvii, i Abt. : 494, 1882.
Heinsen, E. — Die Makrosporen und weibliches Prothallium von Selagi-

nella. Flora, Ixxviii : 466, 1894.
HiERONYMUS, G. (and Sadebeck, R.). — Selagincllaceae. Engler and

Prantl, Nat. Pflanzenfam. i Abt., iv : 621-715, 1901.
HiLDEBRAKD, F. — Brutkorper von Bryum annotinum. Flora, Ivi : 513,

1874.
HiRASE, S. (see also "Ikeno"). — i. Etudes sur la fecondation et I'embry-

ogenie du Ginkgo biloba. Journal Coll. Sci. Imp. University, Tokyo,

xii: 103-1491, 1898.
HiRSCH, Pauline E. — The Development of Air-chambers in the Ricciaceae.

Bull. Torrey Bot. Club, xxxvii : 73-77, 1910.
HoBKiRK, C. P. — On some points in the development of Osmunda regalis.

Journal of Botany, xi : 97, 1882.
HoFMEiSTER,W. — I. The Higher Cryptogamia. Ray Society, 1862. This

contains a translation of the " Vergleichende Untersuchungen," as well

as the later papers upon the Archegoniatae.

2. ijber die Zellenfolge im Achsenscheitel der Laubmoose. Bot.
Zeit., xxviii : 441,457,473-1870.
HoLFERTY, G. M. — The Development of the Archegonium of Mnium cuspi-

datum. Bot. Gaz., xxxvii: 106-126, 1904.
HoLLE, J. G. — I. Ueber Bau und Entwickelung der Vegetationsorgane

der Ophioglosseen. Bot. Zeit., 1875, 241.

2. Vegetationsorgane der Marattiaceen. Bot. Zeit., 1876, 215.
HOLLOWAY, J. E. — I. A comparative Study of the Anatomy of six New

Zealand species of Lycopodium. Trans, and Proc. New Zealand

Institute. New Issue, xlii : 356-370? iQOQ-

2. Studies in the New Zealand Species of the Genus Lycopodium.
Part I. Wellington, N. Z., 1916.
HoLTZMAN, C. L. — On apical growth of the stem, and the development

of the sporangium of Botrychiimi Virginiamim. Bot. Gazette, xvii :

214, 1892.
Hooker, Sir J., and Baker, J. G. — Synopsis Filicum. London,

1874.
HoRNE, A. S. — Discharge of Antherozoids in Fossombronia and Haplo-

mitrium. Ann. Bot., xxiii : 159-160, 1909.
Howe, M. A. — i. Gyrothyra, a new genus of Hepaticae. Bull. Torrey

Bot. Club, xxiv: 201-205, 1897.

2. Anthocerotaceffi of North America. Bull. Torrey Bot. Club, xxv:

1-24, 1898.

3. Hepatic£e and Anthocerotes of California. Mem. Torrey Bot.

Club, vii: 1899.

4. (and Underwood, L. M.) . — The Genus Riella, with Descriptions of

662 MOSSES AND FERNS

new species from North America and the Canary Islands. Bull.
Torr. Bot. Club, xxx : 214-224, 1903.

5. Exogenous Origin of the Antheridium in Anthoceros. Torreya, iv :

175, November, 1904.

6. Ox>'mitra (Tesselina) in the United States. Bryologist, xvii : 72-

75, 1914.
Humphrey, H. B. — i. The Development of Fossombronia longisda

Ann. Bot., xx: 83-108, 1906.

2. Studies in the Physiology and IMorpliology of some Californian

Hepaticae. Proc. Wash. Acad. Sciences, xix : 1-50, 1908.

Hutchinson, A. H. — Gametophyte of PcUia cpipJiylla. Bot. Gaz., Ix:

134-143, 1915-
Hy, F. — I. De la structure de la tige des mousses de la famille dcs Poly-

trichacees. Bull, de la Soc. bot. de France, t. xxvii : 106, 1880.

2. Recherches sur I'archegone et le developpement du fruit des Mus-

cinees. Ann. des Sciences Naturelles, series 6, t. 18: 105,

1884.
Ikeno, S. — I. The Spermatozoids of Cycas revoliUa (Japanese). Bot.
Mag., Tokyo: 10, 1896.

2. (and Hirase). — Spermatozoids of Gymnosperms. Ann. of Bot.,

xi: 344, 1897.

3. Untersuchungcn liber die Entwickelung der Geschlectsorgane und

den Vorgang der Befruchtung bei Cycas revoluta. Pringsh.
Jahrb. f. wiss. Bot., xxxii : 557-602, 1898.

4. Die Spermatogenese von Marchantia polymorpha. Beiheft z. Bot.

Centralbl., xv: 65-88,1903.
Janchen, E. — Neuere Vorstellungen liber die Phylogcnie der Pteridophy-

ten. Mitteil. Naturwiss. Ver., Wien, ix., 1911.
Janczewski, Ed. de. — i. Vergleichende Untersuchungcn liber die Ent-

wickelungsgeschichte des Archegoniums. Bot. Zeit., 1872, p. 377.

2. (and RosTAFiNSKi, J.). — Note sur le prothalle de I'Hymenophyl-

lum Tunbridgense. Mem. de la Soc. nationale des Sciences
naturelles de Cherbourg, t. xix, 1875.

3. Recherches sur le developpement des bourgeons dans Ics preles.

Mem. de la Soc. nationale des Sciences naturelles de Cherbourg,
t. XX., 1876.

4. Etudes comparees sur les tubes cribreux. Ann. Sci. Nat. Bot., ser,

6, xiv: 50, 1882.
Janse, J. M. — Les Endophytes radicaux de quelques Plantcs Javanaises.

Ann. du Jard. Bot. de Buitenzorg, xiv: 53-201, 1897.
Jeffrey, E. C. — i. The Gametophyte of Botrychmm Virginianum. Proc.

Canad. Inst., v., 1898.

2. The Development, Structure and Affinities of the Genus Equise-

tum. Mem. Boston Soc. Nat. Hist., v. No. 5, 1899.

3. The Structure and Development of the Stem in Pteridophytes and

BIBLIOGRAPHY 663

Gymnosperms. Phil. Trans. Roy. Soc, ser. B, vol. 195: 119-

146, 1902,
4. The Pteropsida. Bot. Gaz., 1: 401-414, 1910.
Johnson, D. S. — i. On the Development of the Leaf and Sporocarp in
Marsilia quadrifolia, L. Ann. of Bot., xii : 1 19-145, 1898.

2. On the Leaf and Sporocarp of Pilularia. Bot. Gaz., xxvi : 1-24,

1898.

3. The Development and Relationship of Monoclea. Bot. Gaz.,

xxxviii : 185-205, 1904.
JONKMAN, H. F. — I. La generation sexuee des Marattiacees. Arch.
Neerlandaises, etc., t. xv: 199, 1880. Also in Bot. Zeit., 1878, p. 129.

2. Over de Keimung van Kaulfussia aesculifolia. Nederland.

Kruidkdg. Archief, ser. 2, deel. 3, stuck 2, p. 262, 1879.

3. L'Embryogenie de I'Angiopteris et du Marattia. Archiv. Neerland.

t, xxx: 213-230. (Separate, not dated.)
JuEL, O. — Uber den anatomischen Bau von Riccia Bischoffii. Svensk

Bot. Tidskr., 160-166, 1910.
JURANYi, L. — I, Ueber den Bau und die Entwickelung des Sporangiums

von Psilotum triquetrum Sw, Bot. Zeit., 1871, p. 176.

2. Ueber die Entwickelung der Sporangien und Sporen von Salvinia

natans, Berlin, 1873.

3. Ueber die Gestaltung der Frucht bei Pilularia globulifera. Review,

Bot. Centralb., i : 207, 1880.

Kainradt, E. — Uber ein Makrosporangium mit mehreren Sporentetraden

von Selaginella helvetica, und entwickelungsgeschichtliche Unter-

suchungen iiber die Makrosporangien unserer einheimischen Selaginel-

leen. Sitzungsber. K. Ak. Wiss., Wien, 191 2.

Kamerling, Z. — Zur Biologic und Physiologic der Marchantiaceen.

Flora, Ixxxiv: 1-68, 1897, Erganzungsb.
Karsten, G. — I. Beitrage zur Kenntniss von Fegatella conica. Botan-
ische Zeitung, 1887, p. 649.

2. Morphologische und biologische Untersuchungen iiber einige Epi-
phytenformen der Molukken. Ann. du Jard. Bot. de Buiten-
zorg, xii: 1 17-195, 1895.
Kashyap-Shiv, R. — I. The Structure and Development of the Pro-
thallus of Equisetum dehile. Ann. Bot., xxviii : 163-181, 1914.
2. Morphological and Biological Notes on new and little known Hima-
layan Liverworts. I. New Phytologist, xiii : 206-225, 1914.
II. New Phytologist, xiii: 208-723, 1914. III. New Phy-
tologist, xiv: 1-18, 1915.
KiDSTON, R., and Gwynne-Vaughn, D. T. — On the Fossil Osmundaceae.

Trans. Roy. Soc. Edinb., xlvii : 19 10.
Kienitz-Gerloff, F. — i. Vergleichende Untersuchungen iiber die Ent-
wickelungsgeschichte des Lebermoossporogons. Bot. Zeit., 1874, 161 ;
1875, 777.

664 MOSSES AND FERNS

2. Untersuchungen iiber die Entwickelungsgeschichte der Laubmoos-

kapsel, und die Embryoentwickelung einiger Polypodiaceen.
Bot. Zeit., xxxvi: ^s, 49> 1878.

3. IMorphologische Bedeutung der Laubmooskapsel in Vergleich zur

Lebermoosfrucht. Sitzungsberichte der Gesellschaft. naturf.
Freunde, Berlin, 1876.

4. Genetische Zusammenhang von IMoose und Gefasskryptogamen.

Botanische Zeitung, 1876, 705.

5. Ueber Wachsthum und Zelltheilung in der Entwickelung des Em-

bryos von Isoetes lacustris. Bot. Zeit., 1881, 761.

6. Ueber die Bedeutung der Paraphysen im Anschluss an H. Leitgeb's

"Wasserausscheidung an den Archegonienstande von Corsinia."
Botanische Zeitung, 1886, 248.
King, C. A. — Explosive Discharge of Antherozoids in Conocephalum.

Torrya, iii : 60, 1903.
Klebs, G. — Die Bedingungen der Fortpflanzung bei einigen Algen und

Pilzen, Jena, 1896.
Klein, J. — Sprossung an den Inflorescenzstielen von Marchantia poly-

morpha. Botanisches Centralblatt, v : 26,1881.
Klein, L. — i. Bau und Verzweigung einiger dorsiventralgebauter Poly-
podiaceen. Nova Acta Acad. Caes. Leop. Carol. Nat. Cur. T. xlii :
335, 1881. Review, Bot. Zeit., 1882, 911.

2. Vergleichende Untersuchungen iiber Organbildung und Wachs-
thum am Vegetationspunkte dorsiventraler Fame. Bot. Zeit.,
1884, 577.
Kny, L. — I. Beitrage zur Entwickelungsgeschichte der laubigen Leber-
moosen. Pringsheims Jahrb. fiir wiss. Botanik, iv: 64, 1865.

2. Ueber Bau und Entwickelung der Riccien. Ibid.,v: 364.

3. Entwickelung des Vorkeims der Polypodiaceen und Schizaeaceen.

Sitzber. d. Gesellschaft. naturf. Freund., Berlin, 1868.

4. Ueber Bau und Entwickelung des Farnantheridiums. Monatsber.

d. Berlin. Akad., 1869, p. 416.

5. Beitrage zur Entwickelungsgeschichte der Farnkriiuter. I. Os-

munda rcgalis. Pringsh. Jahrb. f. wiss. Bot., viii : i, 1872.

6. Treppengefasse in Farnprothallicn. Verhandl. des bot. Vereins der

Prov. Brandenburg, Jahrg., xvi : 71, 1874.

7. Entwickelung der Parkeriaceen dargestellt an Ceratopteris thalic-

troides. Nova Acta Acad. Caes. Leop. Carol. Nat. Cur., T.
xxxvii : No. 4, 1875.

8. Durchwachsung an dem Wurzelhaare zweier Marchantiaceen.

Verhandl. des bot. Vereins der Prov. Brandenburg, Jahrgang 21,
1879, p. 2.

9. Entwickelung von Aspidium filix-mas., i Theil. Berlin, 1895.
Koch, L. — Ueber Bau und Wachstum der Wurzelspitze von Angiop-

teris evecta. Pringsh. Jahrb. f. wiss. Botanik, xxvii : 369, 1895.

BIBLIOGRjiPHY 665

Kruch, O. — I. Istolog a ed istogenia del fascio conduttore delle foglie di
Isoetes. Malpighia, An. iv. : 56,1890.

2. Appunti sullo sviluppo degli organi sessuali c sulla fecondazione
della Riella Clausonis. Malpighia, vol. iv : 403 i Genoa, 1890,
1891.
KuHN, R. — I. Zur Entwickelungsgeschichtc der Andreseaceen. Schenk
und Luerssen, Mitthl. aus dem Gesammtgebiete d. Botanik, vol. i.

2. Untersuchungen uber die Anatomie der Marattiaceen und anderen

Gefasskryptogamen. Flora, Ixxii : 457, 1889.

3. Ueber'den anatomischen Bau von Danaea. Flora, Ixxiii: 147,

1890.
KuNDiG, J. — Beitrage zur Entwickelungsgeschichtc des Polypodiaceen-

sporangiums. Hedwigia, xxvii, Heft i : i, 1888.
KuNDT, A. — Die Entwickelung der Micro- and Makrosporangien von

Salvinia natans. Beiheft. Bot. CentralbL, xxvii: Abt. i, 26-51, 1911.
KUPPER, W. — iJber Knospenbildung an Farnblatter. Flora, xcvi : 337-

408, 1906.
KuRSSANOW, L. — Eine Notiz zur Frage iiber die Phylogenie des Arche-

goniums. Bull. Soc. Nat. Moskva, xxii : 39-43, iQio-
KtJSTER, W. — Die Oelkorper der Lebermoose und ihr Verhaltniss zu den

Elaioplasten, Basel, 1894.
Laage, a. — Bedingungen der Keimung von Earn- und Moossporen.

44 pp., Halle, 1906.
Lachmann, p. — I. De Taccroissement terminale de la racine de Todea

barbara. Bui. de la Soc. botanique de Lyon, 1884, p. 42.

2. Sur I'origine des racines chez les fougeres. Bui. de la Soc. bot. de

France, XXX : 33,1884.

3. Sur le systeme libero-ligneux des fougeres. Bui. de la Soc. bot. de

Lyon, p. ss, 1884.

4. Recherches anatomiques sur les Davallia. Bui. de la Soc. botanique

de Lyon, 1886.

5. Sur la structure de la racine des Hymenophyllacees. Ibid.,

1886.

6. Structure et croissance de la racine des fougeres, et I'origine des

radicelles. Bui. de la Soc. bot. de Lyon, 1887.

7. Insertion des Racines. Ann. de la Soc. bot. Lyon, 1889.
Lamothe, a. — Le gametophyte des Marchantiales. De I'importance de

ses characteres anatomiques. Compt. rend. Paris, civ: 1093-1096,

1912.
Lampa, Emma. — i. Untersuchungen an einigen Lebermoosen. Sitzungs-

ber. der Kais. Akad. der Wiss., Wien, cxi : 477-489, 1902.

2. Uber die Beziehung zwischen dem Lebermoosethallus und dem
FarnprothalHum. Osterr. Bot. Zeitschr., lix : 409-414, 1909-
Land, W. J. S. (See also, Barnes). — A protocorm of Ophioglossum,

Bot. Gaz., lii: 478-479, 1911.

666

MOSSES AND FERNS

Lang, W. H. — i. Alternation of Generations in the Archegoniates.
Ann. of Bot., xii : 583-592, 1898.

2. On Apogamy and the Development of Sporangia upon Fern-pro-

thalli. Phil. Trans. Roy. Soc, ser. B, vol. 190, 1898.

3. On Apospory in A nthoccros lewis. Ann. of Bot., xv : 503-510, 1901.

4. On the Prothalli of 0 phioglossiim pendulum and Helminlhostachys

zcylanica. Ann. of Bot., xvi : 23-56, 1902.
On a Prothallus provisionally referred to Psilotum. Ann. of Bot.,

xviii: 571-577, i904-
On the Morphology of Cyathodium. Ann. Bot., xix: 411-426,

1905.
On the Sporogonium of Notothylas. Ann. Bot., xxi : 201-211,

1907.
8. A theory of Alternation of Generations, based on Ontogeny.

New Phytologist, viii : 1-2, 1909.
On a Suspensor in Helminthostachys. Ann. Bot., xxiv: 611,

1910.

10. On the Interpretation of the Vascular Anatomy of the Ophio-

glossaceai. Mem. Proc. Manchester Liter, and Phil. Soc,
Ivi : Part II. No. 12, 191 2.

11. Studies in the Anatomy of the Ophioglossaceae. I. On the

Branching of Botrychium Lunaria. Ann. Bot., xxvii : 203-
242, 1913.

12. The Embryo of Helminthostachys. Ann. Bot., xxviii : 19-37,

1914.

13. The Anatomy and Branching of the Rhizome of Helminthostachys.

Ann. Bot., xxix : 1-54, 191 5.

14. Studies in the Morphology of Isoetes, I. The Stock of Isoetes
. lacustris. Mem. and Proc. Manchester Lit. and Phil. Soc,

lix : 28 pp., 1915.
Lawson, a. a. — I. The Prothallus of Tmesipteris Tanncnsis. Trans.
Royal Soc. Edinb., li, Part III : 785-794, 191 7.
2. The Gametophyte Generation of the Psilotaceae. Ibid., hi. Part

i: 93-113, 1917-
Leavitt, R. G. — I. The Root-hairs, Cap and Sheath of Azolla. Bot.
Gaz.,xxxiv: 414-418, 1902.
2. Trichomes of the Roots in Vascular Cryptogams and Angiosperms.
Proc. Boston Soc. Nat. Hist., xxxi : 273-313, 1904.
Leclerc du Sablon. — I. Sur le sporogone des Hepatiques et le role
des elateres. Bulletin de la Soc. bot. de France, t. xxxii, pt. i : 30,

1885.

2. Sur la developpement du sporogone de Frullania dilatata. Bui. de

la Soc. bot. de France, t. xxxii, pt. 4 : p. 187, 1885.

3. Recherches sur la developpement du sporogone des Hepatiques.

Ann. des Sci. naturelles, ser. vii, t. ii : 126-180, 1885.

BIBLIOGILiPHY 667

4. Recherches sur le dissemination des spores chez les crypto-

games vasculaires. Ann. des Sci. naturelles, ser. vii, t. ii : 5,
1885.

5. Sur les anlherozoidcs du Cheilanthcs hirta. Bui. de la Soc. bot. de

France, t. xxxv : 238, 1888.

6. Reviviscence de Selaginella lepidophylla. Ibid., p. 109.

7. Sur Tendoderme de la tige des Selaginelles. Journal de Botanique,

1889, 207.

8. Recherches anatomiques sur la formation de la tige des fougeres-

Annales des Sci. naturelles, ser. vii, t. xi : i, 1890.

9. Sur les tubercules des Equisetacees. Rev. generale de

Botanique, t. iv : 1892,97.
10. Sur le developpement du sporogone des Mousses. Rev. gener.

Bot., xvii: No. 197, 193-197, 1905.
Leitgeb, Hubert. — i. Wachsthum des Stammchens von Fontinalis und
Sphagnum. Sitzb. d. kais. Akad. d. Wissenschaften, Wien, Bd. Ivii,
Abt. i: 308, 1868.

2. Entwickelung der Antheridien bei Fontinalis antipyretica. Sitz-

ber. der k. Akad. d. Wiss., Wien, Iviii, Abt. i: 525, 1868.

3. Ueber Schistostega. Mittheilung des naturwiss. Vereines, Graz,

1874.

4. Zur Kenntniss des Wachsthums von Fissidens. Sitzungsberichte

der kaiserlichen Akademie der Naturwissenschaften, Wien, Bd.
Ixix, Abt. i: 47, 1874.

5. Verzweigte Moossporangien. Naturwissenschaftliche Verein fiir

Steiermark, 1876.

6. Ueber Zoopsis. Naturwissenschaftliche Verein fiir Steiermark,

1876.

7. Untersuchungen iiber die Lebermoose, 1874-1881, 6 volumes.

Vol. i, Blasia pusilla; vol. ii. Die foliosen Jungermannieen ;
vol. iii, Die frondosen Jungermannieen; vol. iv. Die Ricceen;
vol. V, Die Anthoceroteen ; vol. vi. Die IVIarchantieen.

8. Das Sporogon von Archidium. Sitzber. der kais. Akad. der

Wiss., Wien, Ixxx, Abt. i: 447, 1879.

9. Ueber BilateraHtiit der Prothallien. Flora, Ixii : 317,1879.

10. Die Antheridienstande der Laubmoose. Flora, Ixv : 467,

1882.

11. Ueber Bau und Entwickelung einiger Sporen. Ber. der deutsch.

bot. Gesellschaft, Bd. i : 246, 1883.

12. Ueber Bau und Entwickelung der Sporenhaute und deren Ver-

halten bei der Keimung. Graz, 1884.

13. Wasserauscheidung an den Archegonienstande von Corsinia.

Flora, Ixviii: 327, 1885.

14. Sprossbildung an apogamen Farnprothallien. Ber. der deut-

schen bot. Gesellschaft, iii : 169, 1885.

668 MOSSES AND FERNS

15. Die Stellung der Fruchtsacke bei den geocalycen Jungermannieen.
Sitzber. der kais. Akad. der Wissenschaften, Wien, Bd. Ixxxiii, i
Abt. : 515, 1881.
Lesage, p. — I. Croissance du sporogone en dehors de la plante-mere

de Pellia epiphylla. Extr. du Bull. Soc. scientif. et med. de I'Ouest.,

xix : Rennes, 1910.

2. Croissance comparee du sporogone de Polytrichum formosum sur
la plante-mere et en dehors de la plante-mere.
Lewis, C. E. — The Embryology and Development of Riccia lutescens and

R. crystallina. Bot. Gaz., xli : 1 10-138, 1906.
Lieuwen-Reijnvaan, W. and J. Van. — Uber die Spermatogenese der

Moose, speciell mit Beriicksichtigung der Zentrosomen- und Reduc-

tionsteilungfragen. Ber. Deutsch. Bot. Gesell, xxvi : 301-309, 1908.
Lignier, O. — I . Equisetales et Sphenophyllales. Leur origine filicineenne

commune. Bull, de la Soc. Linn, de Normandie, ser. 5, vol. 7. Caen,

1903.

2. Sur I'origine des Sphenophyllales. Bull. Soc. Bot. de France,
Iv : 278, 1908.
LiLlENFELD, F. — Beitrage zur Kenntniss der Art Haplomitrium Hookeri.

Bull. int. Ac. Sc. Cracou, Ser. B : 315-339, 191 1.
LiMPRiCHT, G. — I. Ueber Tiipfclbildung bei Laubmoosen. Schlesische

botanische Gesellschaft, 1884, 289.

2. Ueber die Porenbildung in der Stengelrinde von Sphagnum. Ibid.,
199, 1885.
LORCH, W. — Die Polytrichaceen. Eine biologische Monographie. Ab-

handl. Kgl. Bayer. Akad. d. Wissensch. 2 Kl., xxiii : 445-546,

1908.
LoTSY, J. P. — Vortrage iiber botanische Stammesgeschichte. Band II.

Jena, 1909.
LuERSSEN, C. — I. Spaltoffnungen von Kaulfussia. Bot. Zeit., 1873,

625.

2. Dickenwachsthum innerer Parenchymzellen der Marattiaceen.

Botanische Zeitung, 1873, 641.

3. Zur .Keimungsgeschichte der Osmundaceen, vorziiglich der Gattung

Todea. JMittheilungen aus dem Gesammtgebicte der Botanik,
Schenk und Luerssen, Bd. i : 460.

4. Ueber Farnsporangicn. Ibid., Bd. ii : i.

5. Ueber die Entwickelungsgeschichte des Marattiaceenvorkeims,

Bot. Zeit, 535, 1875.

6. Handbuch der systematischen Botanik. Bd. i., Kryptogamen.

Leipzig, 1879.

7. Die Farnpflanzen oder Gefassbiindelkryptogamen (Rabenhorst,

Kryptogamcnflora). Leipzig, 1 884-1 889.
LuTZ. — Sur I'origine des canaux gommiferes des Marattiacees. Jour, de
Botanique, xii : 133-35, 1898.

BIBLIOGRAPHY 669

Lyon, Miss F. M. — i. A Study of the Gametophytes of Selaginella apiis.

and S. rupestris. Bot. Gaz., xxxii : 124-141, 170-194, 1901.

2. The Evolution of the Sex-organs of Plants. Bot. Gaz., xxxvii :
281-293, 1904.
Lyon, H. L. — i. Polyembryony in Sphagnum. Bot. Gaz., xxxix: 365-

366, 1905.

2. A New Genus of Ophioglossacea}. Bot. Gaz., xl : 455-458, i9o5-
MacMillan, C. — I. On the casting off of parts of the Aquatic Hairs of

AzoUa. Quart. Bull. Univ. of Minn., 1895.

2. Some Considerations on the Alternation of Generations in Plants.
Lincoln, Neb., 1896.
McAllister, F. — The Morphology of Thallocarpus Curtisii. Bull.

Torry. Bot. Club, xliii : 117-126, 1915.
McCoRMiCK, Florence A. — A study of Symphyogyna aspera. Bot.

Gaz., Iviii: 419-431,1914.
McFadden, Effie B. — The Development of the Antheridium of Targionia

hypophylla. Bull. Torr. Bot. Club, xxiii : 242-244,1896.
McNicoL, Mary. — On Cavity-parenchyma and Tyloses in Ferns. Ann.

Bot., xxii : 401-413, 1908.
Manning, Florence L. — Life history of Porella platyphylla. Bot. Gaz.,

xlvii: 320-322, 1914.
Marchal, El. and Em. — i. Recherches experimentales sur la sexuahte

des spores chez les mousses. Mem. couronnes, CI. Sc. Acad. Roy-

Belgiques. 2. ser. t. i, 1906.

2. Aposporie et sexualite chez les Mousses. Bull. Acad. Roy-

Belgique, 1907 : 765-789.

3. Marchal, Em. Recherches cytologiques sur le genre Amblystegium.

Bull. Soc. Roy-Belgique, U: pp. 15, 1912.
Marquette, W. — Concerning the Organization of the spore mother-cells

of Marsilia quadrifolia. Trans. Wiscon. Acad. Sc. Arts and Letters,

xvi: 81-106, 1908.
Mathuschek, Franz. — Die Adventivknospen an den Wedeln von Cys-

topteris bulbifera. Oesterreichische botanische Zeitschrift, 1894, 121-

124; 177-178.
Mettenius, Georg. — I. Beitrage zur Kenntniss der Rhizocarpeen.

Frankfurt-am-Main, 1846.

2. Filices Hort. bot. Lips., 1856.

3. Ueber Phylloglossum. Bot. Zeit., 1867, p. 97-

Meunier, Alph. — La Pilulaire. Etude anatomico-genetique du sporo-
carpe chez la Pilularia globulifera — La Cellule, iv : 319, 1887.

Meyer, K. — i. Untersuchungen iiber den Sporophyt der Lebermoose.
Bull. Soc. Imp. Nat. Moscow, 191 1.

2. Entwickelung des Sporogons der Corsinia marchantioides. Bull.

Soc. Imp. Nat. Moscow: 263-286, 1912.

3. Zur Frage von der Homologie der Geschlechtsorgane und der

670 AIOSSES AND FERNS

Phylogenie des Archegoniums. Biol. Zeitschr., xi: 177-187,
1912.

4. Untersuchungen iiber den Sporophyt der Lebermoose II. Die

Entwickelungsgeschichte des Sporogons bei Plagiochasma.
Bull, de la Soc. imper. des Nat. de Moscou. 597-615, 1913.

5. A Study of the Sporophyte in the Liverworts of the Group of the

Marchantiales. Moscow, 1916. (Russian.)
MiLDE, J. — I. ;Monographia Equisetorum. Nova Acta Acad. Caes.
Leopold Carol., Nat. Cur., xxxii, pars ii : p. i, 1867.

2. JMonographia generis Osmundae. Bot. Zeit., 1868, 800, and Flora,

lii : 54, 1869.

3. Monographia Botrychiorum. Verhandl. d. zool. bot. Gesell.,

Wien. Bd. xix : p. 55, 1869.
MiLL.\RDET, A. — Le prothallium male des cryptogames vasculaires.

Strassburg, 1869.
Mitchell, G. — Contributions toward a knowledge of the genus Sela-

ginella. Part V. The Strobilus. Ann. Bot., xxiv: 19-32,1910.
MiYAKE, K. — I. On the spermatozoid of Ginkgo. Bot. Mag., Tokyo,

xii: 337-339, 1898.

2. Makinoa, a New Genus of Hepaticai. Bot. Mag., Tokyo, xiii : 1-4,

1899.
MoNTEVERDE, N. A. — Ucber krystallinische Ablagcrungen bei Marattia.

Arbeiten der St. Petersburg Naturforscher-Gesellschaft, t. xvii., 1886.
;Moore, a. C. — I. The Mitoses in the Spore Mother-Cell of Pallavicinia.

Bot. Gaz., xxxvi: 384-388, 1903.

2. Sporogenesis in Pallavicina. Bot. Gaz., xl: 81-96, 1905.
MoRiN, F. — Anatomie comparee et experimentale de la Famille des

Muscinees. Review, Botanisches Centralblatt, Iviii : 164, 1894.
Mother, D. M. — i. Notes on the apical growth of Liverworts. Bot.

Gazette, xvi: 141,1891.

2. Contributions to the Life-History of Notothylas. Ann. of Bot.

viii: 391, 1894.

3. Fecundation in Plants. Carnegie Institute, 1904.

4. Notes on the sex of the Gametophyte of Onoclea Struthioptcris.

Bot. Gaz., 1: 209-213, 1910.
MuLLER, Carl. — i. Ueber den Bau der Commissuren der Equisetum-
scheiden. Pringsheims Jahrb. fiir wiss. Botanik, xix: 497, 1888.
2. Zur Kcnntniss der Entwickelungsgeschichte des Polypodiaceen-
sporangiums. Berichte der deutsch. botan. Gesellschaft, xi : 54,

1893.
MiJLLER, Carl (and Ritilaxd, W.). — 3. Die Laubmoose. Engler and

Prantl, Die Nat. Ptlanzenf., Theil i, Abt. iii : 152-243, 1898-1901.
MuLLER, Hermann. — Sporenvorkeim und Zweigvorkeime der Laubmoose.

Arbeiten des botanischcn Instituts zu Wurzburg, Bd. i : 475.
MiJLLER, N. J. C. — I. Das Wachsthum des Vegetationspunktcs von

BIBLIOGILiPHY 671

Pflanzen mit decussirter Blattstellung. Pringsh. Jahrb. f. wiss.

Botanik, V : 247,1866-67.

2. Die Entwickclungsgeschichte der Kapscl von Ephemerum.
Pringsh. Jahrb. fiir wiss. Bot., vi : 237, 1867-68.
Nawaschin, S. — Was Sind eigentlich die sogenanntcn Microsporen der

Torfmoosen? Bot. Centralblatt, xliii., p. 289, 1890.
Nemec, B. — I. Die Induktion der DorsiventraHtat bei einigen Moosen.

Bull, international de I'Academie des Sciences de Boheme, ix, 1904.

2. Die Symmetrieverhaltnisse iind Wachstumsrichtungen einiger

Laubmoose. Jahrb. f. Wissensch. Botanik, xliii: 501-579,
1906.

3. Die Induction der DorsiventraHtat bei einiger Moose. II. Bull.

internat. de I'Acad. Sc. Boheme, xi : 1-7, 1907.

4. Das Problem der Befruchtungsvorgiinge und andere cytologische

Fragen. Berlin, 1910.
Newcomb, F. C. — Spore Dissemination of Equisetum. Bot. Gazette, xiii :

173, 1888.
O'Keefe, Lillian. — Structure and Development of Targionia hypophylla.

New Phytologist, xiv: 105-116, 1915.
Oliver, F. W. — Pteridosperms and Angiosperms. New Phytologist, v :

232-242, 1906.
Oltmanns, F. — I . Zur Entwicklungsgeschichte der Florideen. Bot. Zeit.,

Ivi: 154, 1898.

2. Morphologic und Biologic der Algen. Jena, 1904.
Osterhout, W. J. V. — Ueber Entstehung der Karyokinetischen Spindel

bei Equisetum. Pringsh. Jahrb. f. wiss. Botanik, xxx: 159-168, 1897.
Pedersen, R. — Entwickclungsgeschichte des Polypodiaceenvorkeims.

Mittheilungen aus dem Gesammtgebiete der Botanik. Schenk und

Luerssen, Bd. ii, p. 130, 1875.
Peirce, G. J. — I. Forcible Discharge of Antherozoids in Asterella Calif ar-
nica. Bull. Torr. Bot. Club, xxix: 374-382, 1902.

2. Anthoceros and its Nostoc Colonies. Bot. Gaz., xlii : 55-59, 1906.

3. Studies of Irritability in Plants. The formative influence of light.

Ann. Bot. xx: 449-465, 1906.

Perrin, G. — Sur les prothalles d'Equisetum. C. R. Acad. Sc. Paris,
cliii : 197-199, 191 1.

Petry, Loren C. — The Anatomy of Ophioglossum pendulum. Bot. Gaz.,
xlvii : 169-192,1914.

Pfeffer, W. — I. Die Entwickelung des Keimes der Gattung Selaginella.
Botanische Abhandlungen, etc., herausgegeben von Dr. Johannes Han-
stein. Bonn, 1871.

2. Die Oelkorper der Lebermoose. Flora, Ivii: 2,1874.

3. Locomotorische Richtungsbewegungen durch chemische Reize.

Untersuch. aus dem bot. Institute zu Tubingen, Bd. i. 1884,

363.

672 MOSSES AND FERNS

Pfitzer. — Ueber die Schutzscheide der deutschcn Equisetaceen. Pringsh.

Jahrb. f. wiss. Bot., vi : 292, 1867-^8.
PiccoNE, A. — Notizic e osservazioni sopra 1' Isoetes Durieui. Nuovo Gior-

nale Botanico Italiano, viii : 1876.
Pickett, F. L. — The Development of the Prothallium of Camptosorus

rhizophyllus. Bot. Gaz., xlvii : 228-238, 1914.
PiETCH, W. — Entwickelungsgeschichte dcs vegetativen thallus, insbeson-

dere der Luftkammem der Riccicn. Flora, ciii : 247-284, 191 1.
Plant, iM. — Untersuchungen iil)er die physiologischen Scheiden der

Gymnospermeii, Equisetaceen und Bryophyten. Pringsh. Jahrb.

wiss. Bot., xlvii: 121-185, 1909.
PoiRAULT, G. — I . Recherches d'histogenie vegetale. Developpcment des

tissus dans les organes vegetifs des cryptogames vasculaires. Mem. do

I'Acad. imp. des sciences de St. Petersbourg, ser. vii., t. xxxvii, 1890.

2. Sur rOphioglossum vulgatum. Journal de Botaniquc, vi, 1891.

3. Recherches anatomiques sur les cryptogames vasculaires. Ann. dcs

Sciences naturelles, ser. vii, t. xviii : 113, 1893.
PoTONiE, H. — I. Anatomic der Lenticcllen der Marattiaceen. Jahrb. des
bot. Gartens, Berlin, 1881, p. 307, Bd. i.

2. Ueber den Bau der Leitbiindcl der Polypodiaceen und liber den Be-

griff des Leitbiindels bei den Gefasskryptogamen. Verhandl. des
Verreins fur Naturwiss. der Prov. Brandenburg, Jahrg. xxiv:
77, 1882.

3. Lehrbuch der Pflanzenpaltcontologie. Berlin, 1899.

4. Fossil Pteridophytes in Engler and Prantl, Die naturlichen Pflan-

zen familien. Theil i, Abt. iv.
Prantl, K. — i. Die Hymenophyllaceen. Untersuchungen zur Mor-
phologic der Gefasscryptogamen, vol. i. Leipzig, 1875.

2. Morphologischc Studien. Flora, Iviii : 537^1875.

3. Ueber die Anordnung der Zellen in flachenformigen Prothallien

der Fame. Flora, xxxvi : 497-511, 530-543. 545-556, 1878.

4. Zur Entwickelungsgeschichte des Prothalliums von Salvinia natans.

Bot. Zeit., 1879, p. 425.

5. Die Schiza^aceen. Untersuchungen zur Morphologic der Gefass-

kryptogamen, vol. ii : Leipzig, 1881.

6. Die Farngattungen Cryptogramme und Pella^a. Engler's bo-

tanisches Jahrbuch, ii : 403, 1882.

7. Helminthostachys Zeylanica in ihre Beziehung zu Ophioglossum

und Botrychium. Ber. der deutsch. bot. Gesellschaft, i: 155,
1883.

8. Systematisches Uebersicht der Ophioglosseen. Ihid., 348.

9. Beitrag zur Systematik der Ophioglosseen. Jahrbuch des bot.

Gartens, Berhn, Bd. iii : 297, 1884.
10. Die :vlechanik des Rings am Farnsporangium. Ber. deutsch.
botan. Gesellsch., iv : 42, 1886.

BIBLIOGRAPHY 673

Prescher, R. — Die Schleimorgane der Marchantien. Sitzungsber. der
Kais. Akad. der Wiss., Wicn, Ixxxvi : 132-158, 1882.

Pringsheim, N. — I. Zur Morphologie der Salvinia natans. Pringsh.
Jahrb. fiir wiss. Botanik, iii : 484, 1863.

2. Vegetative Sprossung der Moosfriichte. Monatsbericht der

koniglichen Akademie der Wissenschaften zu Berlin, 1876, p.

425-

3. Sprossung der Moosfrucht und Generationswechsel der Thallophy-

ten. Pringsheims Jahrbiicher fiir wiss. Botanik, Bd. xi : i,
1878.
Pritzel, E. — Lycopodiaceaj, Psilotaceae. Engler and Prantl, Nat. Pflan-

zenf., I Th. Abt. iv : 563-619, 1900.
Quelle, F. — Bemerkungen iiber die Rhizoideninitialen in der Ventral-

schuppen der Marchantiaceen. Hedwigia, xli : 176,1902.
Raciborski, M. — Ueber die Osmundaceen und Schizaeaceen der Juraforma-

tion. Engler, Jahrbuch fiir Systematik-Pflanzengeschichte und Pflan-

zengeographie, xiii : i, 1891.
Rauwenhoff, N. W. p. — I. Einiges iiber die ersten Keimungserscheinun-

gen der Kryptogamensporen, Bot. Zeit., 1879, p. 441.

2. La generation sexuee des Gleicheniacees. Archives Neerlandaises
des Sciences exactes et naturelles, t. xxiv: 157, 1891.
Reess, M. — I. Zur Entwickelungsgeschichte des Polypodiaceen-Sporan-

giums. Pringsh. Jahrb. fiir wiss. Botanik, vol. v: p. 217, 1866-67.

2. Zur Entwickelungsgeschichte der Stammspitze von Equisetum.
Pringsh. Jahrb. fiir wiss. Botanik, vi : 209, 1867-68,
Roll, J. — Ueber die Veriinderlichkeit der Stengelblatter bei den Torf-

moosen. Bot. Centralblatt, xli: 241, 1890.
RoSTOWZEW, S. — I. Beitrage zur Kenntniss der Gefasskryptogamen. I.

Umbildung von Wurzeln in Sprosse. Flora, Ixxiii : 155, 1890.

2. Recherches sur VOphioglossum vulgatum. Botanisches Central-

blatt, 1: 364, 1892.

3. Die Entwickelungsgeschichte und die Keimung der Adventivknos-

pem bei Cystopteris bulbifera. Ber. der deutschen bot. Gesell-
schaft, 45, 1894.
RozE, E. — Observations sur le prothalle des Fougeres. Bull, de la Soc. bot.

de France, xxviii : 135, 1881.
RuGE, G. — Beitrage zur Kenntniss der Vegetationsorgane der Lebermoose.

Flora, Ixxvii : 279-312,1893.
RuHLAND, W. (and Warnstorf, C.). — Sphagnales, Andreaeales, and Archi-
diaceai. Engler and Prantl, Die nat. Pflanzenf., Theil i, Abt. 3 : 244-
288, 1901.
Russow, E. — I . Vergleichende Untersuchuugen, betreffend die Histiologie
der vegetativen und sporenbildenden Organe und die Entwickelung der
Sporen der Leitbundelkryptogamen. Mem. de I'Acad. imp. des
Sciences de St, Petersbourg, ser. 7, xix : No. i, 1872.
43

674 MOSSES AND FERNS

2. Betrachtungen iiber das Leitbundel und Grundgewebe aus verglei-

chend morphologischem und physiologischem Gesichtspunkte.
Dorpat, 1875.

3. Ueber die Verbreitung der Callusplatten bei den Gefasspflanzen.

Review, Bot. Zeit., 1881, p. 723.

4. Developpement des tubes cribreux. Ann. des Sci. naturelles, ser. 6,

xiv: 167, 1882.

5. Zur Anatomic resp. Physiologic und vcrgleichendcn Anatomic

der Torfmoosen. Dorpat, 1887.
Sadebeck, R, — I. Ueber die Marchantiaccen. Verhandlungcn des bot-
anischen Vereins der Prov. Brandenburg, 1873.

2. Wachsthum der Farnwedel. Vcrhandl. des bot, Vereins der Prov.

Brandenburg, Jahrgang 15, 116, 1873.

3. Die Entwickelung des Farnblattes, Berlin, 1874.

4. Wachsthumsverhaltnisse von Osmunda regalis. Bot. Zeit., 1875,

p. 638.

5. Der Embryo von Equisetum. Bot. Zeit., 1877, p. 44. Also

Pringsheims Jahrb. fiir wiss. Botanik, xi : 575, 1878.

6. Die Gefasskr>'ptogamen. Schenks Handbuch der Botanik,

vol. i, 1882.

7. Pteridophyta, Hymenophyllaceai. Engler and Prantl, Nat. Pflan-

zenf., I, Abt. iv : 1-112, 1899.

8. Hydropteridinea^. Ibid., 381-421, 1900.

9. Equisetaceae. Ibid., 520-548, 1900.
10. Isoetaceae. Ibid., 756-779, 1902.

Satter, a. — I. Beitrage zur Entwickelungsgeschichte des Lebermoosan-

theridiums. Sitzber. der kais. Akad. der Wissenschaften, Wien, Bd. 86,

Abt. i: July, 1882.

2. Zur Kenntniss der Antheridienstiinde einiger Laubmoose. Ber.
deutsch. bot. Gesellsch. ii : 13, 1884.
Schaffner, J. H. — The Centrosomes of Marchantia polymorpha. Ohio

Naturalist, ix : 383-388, 1908.
ScHELLENBERG, H, C. — Zur Entwickelungsgeschichte der Equiseten-

scheide. Ber. deutsch. bot. Gesellsch., xiii : 165, 1895.
ScHENK, H. — Uber die Phylogenie der Archegoniaten und der Characeen.

Bot. Jahrb. f. Systcmatik, xxxii : Heft, i, 1-37, 1908.
ScHiFFNER, V. — I. Hepatica?. In Engler and Prantl, Die nat. Pflanzenf.,

I Th., 3 Abt., 1-141, 1893-95-

2. Morphologischc und biologische. Untersuchungen iiber die Gat-

tungen Grimaldia und Neesiella. Hedwigia, xlvii : 306-320,
1908.

3. Untersuchungen iiber die Marchantiaccengattung Buccgia. Beih.

3. Bot. Ccntrlbl., xxiii, 2 Abt. : 273-200, 1908.

4. Ibid. Phylogenctische Studien iiber die Gattung Monoclea.

Oesterr-Bot. Zeitschr., Ixiii, 1913.

BIBLIOGILiPHY 675

ScfflMPER, A. F. W. — I . Ucber Bau unci Lcbensweise der Epiphyten West
Indicns. Bot. Centralblatt, xvii : p. 192, 1884.

2. Untersuchungen liber die Chlorophyllkorper und die ihnen homo-
logen Gebilde. Pringsh. Jahrb. f. wiss. Botanik, xvi : 1-247,

1885.
SCHIMPER, Ph. W. — Versuch einer Entwickelungsgeschichte der Torf-

moose (Sphagnum) und einer Monographie der in Europa vorkom-

menden Arten dieser Gattung. Stuttgart, 1858.
Schneider, F. — Beitrage zur Entwickelungsgeschichte der Marsihaceen.

Berlin, 191 2.
ScHOENAU, Karl von. — Zur Verzweigung der Laubmoose. Hedwigia,

li: 1-56, 1911.
ScHOUTE, J. C. — Die Stelartheorie. Groningen, 1902.
ScHOTTLANDER, P. — Beitrage zur Kenntniss des Zellkerns und der Sexual-

cellen bei Kryptogamen. Cohn's Beitrage zur Biologic der Pflanzen,

Bd. vi: 267, 1892.
SCHOSTAKOWITSCH, W. — Ucber die Reproductions- und Regenerations-

erscheinungen bei den Lebermoosen. Flora, Ixxix, Erganzungsband :

350-384, 1894.
SCHRENK, J. — The dehiscence of Fern-sporangia. Bulletin of the Torrey

Botanical Club, xiii: 168, 1886.
ScHRODT, J. — Neue Beitrage zur Mechanik der Farnsporangien. Flora,

Ixx: p. 177, 1887.

SCHULZE, H. — Ein Beitrag zur Kenntniss der vegetativen Vermehrung der
Laubmoosen. Bot. Centralblatt, xxxi: 382,1887.

Scott, D. H. — i. Present Position of Morphological Botany. Presi-
dential address before Sec. K, B. A. A. S., 1896.

2. Studies in Fossil Botany. London, 1900. (Also many monographs

on fossil plants.)

3. (and Hill, T. G.).— The Structure of Isoetes hytrix. Ann. of

Bot., xiv: 413-454, 1900-

4. On the Origin of Seed-bearing Plants. Lecture before the Roy.

Inst, of Great Britain, London, 1903.

5. The Present Position of Palaeozoic Botany. Progressus Rei

Botanicae, i: Heft, i, 1907.

6. Ibid. Studies in Fossil Botany, 2d Edit., 1909.
Seward, A. C. — i. Fossil Plants. Vol. i, Cambridge, 1897.

2. On the Structure and Affinities of Matonia pectinata. Phil. Trans.,

ser. B, vol. 191 : 171, 1899.

3. (and Dale, E.). — On the Structure and Affinities of Dipteris.

Phil. Trans., Ser. B, vol. 194: 487-513, iQoi-

4. (and Ford, S. O.). — The Anatomy of Todea, with Notes on the

Geological History and Affinities of the Osmundaceae. Trans.
Linn. Soc. Lond., 2d ser.. Botany, vol. vi, pt. 5 : 237-260, 1903,

5. Fossil Plants, vol. ii., 1910-

676 MOSSES AND FERNS

Sharp, L. W. — i. Spermatogenesis in Equisetum. Bot. Gaz., liv: 89-

119, 1912.

2. Spermatogenesis in Marsilia. Bot. Gaz., Iviii : 419-431, 1914.
Shattuck, C. H. — The origin of Hcterospory in Marsilia. Bot. Gaz.,

xlix: 19-40, 1910.
Shaw, W. R. — i. Parthenogenesis in Marsilia. Bot. Gaz., xxiv: 114-

117, 1897.

2. The Fertilization of Onoclea. Ann. of Bot., xii : 261-285, 1898.

3. Ueber die Blepharoplasten bei Onoclea und Marsilia. Ber.

deutsch. bot. Gesellsch., xvi : 177-184, 1898.
Shreve, F. — Physiology of the Hymenophyllacea^. Carnegie Inst, of

Wash. Yearbook, No. 9.
SiNNOTT, E. W. — I. Foliar Gaps in the Osmundaceae. Ann. Bot., xxiv:
107-118, 1910.

2. The Evolution of the Filicinean Leaf-trace. Ann. Bot., xxv:
167-191, 1911.
Smith, R. Wilson. — The Structure and Development of the Sporo-
phylls and Sporangia of Isoetes. Bot. Gaz., xxix : 225-258, 323-346,

1900.
Solms-Laubach, H. Graf zu. — i. Der Aufbau des Stockes von Psilotum
triquetrum und dessen Entwickelung aus der Brutknospe. Ann. du
Jardin botanique de Buitenzorg, iv : 139, 1884.

2. Fossil Botany. Oxford, Clarendon Press, 1891.

3. Ueber ExormotJicca, erne wenig bekannte Marchantiaceengattung.

Bot. Zeitung, Iv : 1-16, 1897.
SoNNTAG, P. — Ueber Dauer des Scheitelwachsthums und Entwickelungs-

geschichte des Blattes. Pringsheims Jahrb. fiir \viss. Botanik, xviii :

236, 1887.
SouTHWORTH, Effie A. — Structure, development, and distribution of the

stomata oi Equisetum arvcnse. American NaturaHst, xvii : October, 1884.
Spring, A. — Monographic de la famille des Lycopodiacees. Mem. de

TAcad. roy. de Belgique, t. xxiv : pt. i., 1842 ; pt. ii., 1849.
Spruce, R. — i. The Morphology of the leaf of Fissidens. Trimen's

Journal of Botany, xix : p. 98.

2. Hepatica} of the Amazon and of the Andes of Peru and Ecuador.
Trans. Bot. Soc, Edinburgh, vol. xv, 1885.
Stahl, E. — Kiinsthch hervorrufene Protonemabildung. Halleschc Bot.

Zeitung, p. 680, L876.
Starr, Anna M. — A Mexican Aytonia. Bot. Gaz., Ixi : 48-58, 1916.
Stephani, F. — Species Hepaticarum. Bull, de I'Herbier Boissier. Ser.

I, vi-viii: Ser. 2, i-viii, Geneva, 1898-1908.
Stephenson, B. G. — Young Stages of Dicksonia and Cyathea. Tr. and

Proc. New Zealand Instit., xl : 1-16, 1907.
Sterns, E. E. — Bulblets of Lycopodium lucidulum. Bulletin of the Torrey

Botanical Club, xv : 317, 1888.

BIBLIOGILiPHV 677

Stevens, W. C. — On the Development of the Sporangia and Spores of

Aneimia Phyllitidis. Ann. Bot., xxv : 1059-1068, 191 1.
Stiles, W. — The Structure of the atrial shoots of Psilotum jlaccidum Wall.

Ann. Bot., xxiv : 373-387, 1910.
Stokey, Alma G. — i. The Anatomy of Isoetes. Bot. Gaz., xlvii : 311-

335, 1909.

2. The Sporangium of Lycopodium pithyoides. Bot. Gaz., 1: 218-
219, 1910.
Stopes, M. C. — Ancient Plants. London, 1910.
Strasburger, E. — I. Ein Beitrag zur Entwickelungsgeschichte der

Spaltoffnungen. Pringsh. Jahrb. f. wissen. Bot., v: 297, 1866-67.

2. Die Geschlechtsorgane und die Befruchtung bei Marchantia poly-

morpha. Pringsh. Jahrb. f. wissen. Bot. vii : 409.

3. Die Befruchtung bei den Farnkrautern. Ibid., 390.

4. Die Befruchtung bei den Coniferen. Jena, 1869.

5. Die Coniferen und Gnetaceen. Jena, 1872.

6. Ueber Azolla. Jena, 1873.

7. Einige Bemerkungen liber Lycopodiaceen. Bot. Zeit., 1873, P- 81.

8. Die Angiospermen und die Gymnospermen. Jena, 1879.

9. Zellbildung und Zelltheilung. Third edition, Jena, 1880.

10. Das botanische Practicum, second edition, Jena, 1887.

11. Histologische Beitriige, 6 vols., 1888-1900.

12. The periodic reduction of chromosomes in living organisms. Ann.

ofBot., viii: 281,1894.

13. Die Pflanzhchen Zellhaute. Pringsh. Jahrb. f. wiss. Bot., xxxi :

511-596, 1898.

14. Ueber Reductionsteilung. Sitzungsber. der Konigl. Preuss. Akad.

der Wissensch., xviii., 1904 (Sep. 28 p.).

15. Zeitpunkt der Bestimmung des Geschlechts, Apogamie, Partheno-

genese und Reductionsteilung. Histologische Beitriige, Heft. 7,
Jena, 1909.

16. Uber Geschlechtsbestimmende Ursachen. Jahrb. wiss. Bot.,

xlviii : 427-520, 1910.
Sykes, M. G. — I. Tracheids in the nodal region of Equisetum maxi-
mum. New Phytologist, V : 129-132,1906.

2. Notes on the Morphology of the Sporangium-bearing Organs of

the Lycopodiaceae. New Phytologist, vii : 41-60, 1908.

3. The Anatomy and Morphology of Tmesipteris. Ann. Bot., xxii:

63-89, 1908.

4. (and Stiles, W.). — The Cones of the Genus Selaginella. Ann.

Bot., xxiv: 523-536, 1910.

Tansley, a. G., and Chick, E. — On the Structure of Schizcea Malaccana.
Ann. Bot., xvii : 493-310, 1903.

Tansley, A. G. — Lectures on the Evolution of the Filicinean Vas-
cular System. (Reprint from New Phytologist.) Cambridge, 1909.

678 MOSSES AND FERNS

Terletzki, p. — Anatomie der Vegetationsorgane von Struthiopteris Ger*

manica, unci Pteris aquilina. Pringsheims Jahrbiicher fiir wiss. Bot-

anik, xv: 452, 1884.
Thistleton-Dyer, W. F. — Morphology of Selaginella. Nature, 1877,

p. 489.
Thom.¥, K. — Die Blattstiele der Fame. Pringslieims Jahrb. fiir wiss.

Botanik, xvii : 99, 1886.
Thomas, A. P. W. — i. Preliminary Account of the Prothallium of Phyllo-

glossum. Proc. Roy. Soc, Ixix : 285-291, 1901.

2. The affinities of Tmesipteris with the Sphenophyllales. Ibid.j

Ixix : 1902.

3. An Alga-like Fern-prothallium. Ann. of Bot., xvi : 165,1902.
Thuret, G. — I. Discharge of Antherozoids in Fegatella. Mem. de la

Soc. des Sciences Nat. de Cherbourg, t. iv : 216, 1856.

TiLDEN, Josephine E. — On the Morphology of Hepatic Elaters, with
special reference to branching elaters of Conocephalus conicus. Minne-
sota Botanical Studies, Bulletin 9: 43-53, 1894.

TowLE, Phebe M. — Notes on the Life-history of the Mniums. The
Bryologist, ix: 54-56,1906.

Treub, M. — I. Recherches sur les organes de vegetation de Selaginella
Martensii Spr. Musee botanique de Leide, t. ii.

2. Etudes sur les Lycopodiacees. Annales du Jardin botanique de

Buitenzorg, iv., v., vii., 1 884-1 890.
Twiss, E. M. — The Prothallia of Aneimia and Lygodium. Bot. Gaz.,

xlix: 168-181, 1910.
Underwood, L. M. — i . Hepaticoe. In Gray, Manual of Botany of North

Eastern United States, sixth edition, 1890.

3. Index Hepaticarum, part i. Bibliography. Memoirs of the

Torrey Botanical Club, Vol. iv., No. i, 1893.

4. The Evolution of the Hepaticae. Bot. Gazette, xix: 347, 1894.

5. Our native Ferns and their Allies. Sixth edition. New York, 1900.
Vaizey, J. Reynolds. — i. Transpiration of the sporophore of the Musci.

Annals of Botany, i : 73, 1887.

2. On the anatomy and development of the sporogonium of the Mosses.

Journal of the Linn. Society, xxiv: 262, 1888.

3. Preliminary note on the root of Equisetum. Annals of Botany, ii. :

123, 1888.

4. On the morphology of the sporophyte of Splachnum luteum. An-

nals of Botany, v : i, 1890.
Van Tieghem, Ph. — i. Sur quelques points de I'anatomie des crypto-
games vasculaires. Bull, de la Soc. bot. de France, xxv: 169, 1883.

2. (et Douliot). — Sur la PolysteHe. Ann. des Sci. naturellcs, ser. 7,

t. 3: 275, 1886.

3. Sur le dedoublement de I'endodermis dans les cryptogames vas-

culaires. Journal de Botanique, 1888, p. 404.

BIBLIOGRAPHY 679

4. Sur la limite du cylindre centrale et de I'ecorce dans les crypto-

games vasculaires. Journal de Botanique, 1888, p. 369.

5. (et Duliot). Recherches comparatives sur I'origine des membres

endogenes dans les plantes vasculaires. Ann. des Sc. naturelles,
ser. 7, t. viii: i, 1888.

6. Remarques sur la structure de la tige des preles. Journal de

Botanique, 1890, p. 365.

7. Remarques sur la structure de la tige des Ophioglossees. Ihid.y

p. 405-

8. Traite de Botanique, second edition. Paris, 1892.

Vaughn- Jennings, A. (and Hall, K. M.). — Notes on the structure of

Tmesipteris. Proc. Roy. Irish Acad., 1891.
Vines, S. H. — i. On the homologies of the suspensor. Q. J. Mic. Sci.,
xvii: 58, 1878.

2. The Systematic position of Isoetes. Annals of Botany, ii : 117,
1888.
VoCHTiNG, H. — Ueber die Regeneration der Marchantiaceen. Pringsheims

Jahrb. fiir wiss. Bot., xvi : 367, 1885.
VoiGHT, A. — Vergleichende Anatomie der Marchantiaceen. Botanische

Zeitung, 1879, p. 729.
VouK, F. — I. Das Sporogonium von Orthotrichum. Sitzungsber. der
kais. Akad. der Wissenschaften, Wien, Ixxiii : 385, 1876.
2. Die Entwickelung des Embryos von Asplenium Shepherdii. Sitz-
ber. der kais. Akad. der Naturwissenschaften, Wien, Bd. Ixxvi.,
Abt. 1 : 271, 1877.
Waldner, M. — I. Entwickelung des Antheridium von Anthoceros,
Sitzber. der k. Akad. der Wiss., Wien, Bd. Ixxv., Abt. i: 81, 1877.
2. Die Entwickelung der Sporogone von Andreaea und Sphagnum.
Leipzig, 1887.
Watson, W. — Xerophytic adaptations of Bryophytes. New Phytologist,

xiii : 14^-169, 1914.
Webber, H. J. — The Development of the Antherozoids of Zamia. Bot.

Gaz., xxiv: 22, 1897.
Wernham, H. F. — The Morphology of Phylloglossum Drummondii. Ann.

Bot., xxiv: 335-347,1910.
West, Cyril. — i. On the Structure and Development of the Secretory
Tissues of the Marattiaceae. Ann. Bot., xxix: 409-422, 1915.
2. On Stigeosporium Marattiacearum and the Mycorrhiza of the
Marattiaceae. Ann. Bot., xxxi: 77,1917.
Willl\mson, W. C. (and Scott, D. H.). — Further observations on the Or-
ganization of the Fossil Plants of the Coal Measures. Roy. Soc. Phil.
Trans., vol. clxxxv: 863, 1894.
Willis, J. C. — Flowering Plants and Ferns. Cambridge, 1904.
Wilson, M. — i. On spore-formation and nuclear division in Mnium
hornum. Ann. Bot., xxiii: 141-157, 1909.

68o MOSSES AND FERNS

2. Spermatogenesis in the Bryophyta. Ann. Bot., xxv: 415-457,
1911.
WojENOWic. — Beitrage zur Morphologie, Anatomie und Biologie der Se-

laginella lepidophylla. Inaugural Dissertation, Breslau, 1890.
WooDBURN, W. L. — I. Spermatogenesis in certain Hepaticae. Ann. Bot.,

xxv: 299-313, 1911.

2. Spermatogenesis in 5/(15/(7 />«5///a. Ann. Bot., xxvii : 93-101,1913.

3. Spermatogenesis in Mnium offiiie, var. ciliaris (Grev.) C. M. Ann.

Bot., xxix: 441-456,1915.

WORSDELL, W. C. — The Rhizophores of Selaginella. New Phytologist,
ix : 242-253, 1910.

WuiST, E. D. — The physiological condition for the development of monoe-
cious prothallia in Onoclca Struthiopteris. Bot. Gaz., xlix : 216-219,
1910.

Yamanouchi, Sh. — Spermatogenesis, Oogenesis and Fertilization in
Nephrodium. Bot. Gaz., xlv : 145-175, 1908.

Yapp, R. H. — i. On Two Malayan Myrmecophilous Ferns. Ann. Bot.,
xvi: 185-230, 1902.

2. Apogamy in Nephrodium. Bot. Gaz., xlv : 289-318,1908.
Ihid. Chromosomes in Osmunda. Bot. Gaz., xlix: 1-12, 1910.

Yasui, K. — On the Life-history of Salvinia natans. Ann. Bot., xxv : 470-
483,1911.

Yeates, H. R. — The means of distribution of Hepaticaj. New Phytolo-
gist, vii : 167-171, 1908.

Zacharias, E. — I. Ueber die Spermatozoiden. Bot. Zeit., 1881, p. 827.

2. Ueber den Nucleolus. Bot. Zeit., 1885, p. 289.

3. Beitrage zur Kenntniss des Zellkerns in den sexuellen Zellen. Bot.

Zeit., 1887, p. 281.
Zeiller, R. — Afhnites du Genre Laccopteris. Bull, de la Soc. bot. de

France, 1885, p. 21.
Zenetti, p. — Das Leitungssystem im Stamm von Osmunda regalis, L. Bot.

Zeit., liii: 53-78, 1895-
ZiELiNSKi, F. — Beitrage zur Biologie des Archcgoniums und der Haube

der Laubmoose. Flora, c : 1-36, 1909.
Zimmerman, A. — i. Scheitelzellen an den Adventivknospen einiger Fame.

Bot. Centralblatt, vi: 175, 1881.

2. Ueber die Einwirkung des Lichtcs auf dem Marchantieenthallus.
Arbeiten des bot. Instituts in Wiirzburg, Bd. ii., Heft iv., p. 665.

INDEX

Acrocarpae, 218, 623
Acrogynas, 73, 74, 99, 100, loi, 170,
619, 620
asexual reproduction, 118
branching, 104, 117
classification, 119
distribution, 119
gemmae, 118

germination of spores, 113
leaves, 116
traps in leaves, 117
epiphytic, 116
Adiantites, 579
Adiantum, 364, 395, 580

emarginatum, 329, 336; Figs.

181, 185, 188
pedatum, 332; Fig. 180
Adventitious budding, 574

of gametophyte, 277, 350
Adventitious buds, 258
Adventive shoots, 497

Ricciaceae, 27
Air-chambers,

Marchantiaceae, 23, 42, 48, 610,

611, 612
Ricciocarpus, 39, 40, 610
Struthiopteris, 329
Air-space (see Lacunae), 206, 207,^

216
Alethopteris, 585
Algae, I, 2, 9, 14, 121, 227, 230, 564,

56s, 566, 569, 573, 592
Alisma, 548
Alsophila, 307

prothallium, 391
contaminans, 391
Cooperi, Fig. 228

Alternation of generations, 2, 562
antithetic, 569, 574
homologous, 569, 570, 571
Amber, 577, 578
Amblystegium, 193, 194
apical growth, 191
leaf, 192
riparium var. fluitans, 190; Figs.
98, 99
Ameristic prothallia, 314
Amphigastrium, 14, 114

Porella, 102
Amphithecium, 13, 179, 185, 186,

205, 206, 214
Anabaena Azollce, 409, 415
Anacrogynae, 73, 74, 75, 85, 100,
109, 157, 158, 592, 595, 597,
614, 618, 619
calyptra, 98
elaters, 96, 99
germination of spores, 99
spore-division, 98
spores, 99
sporophyte, 94, 95
Andreaea, 161, 165, 187, 196, 201,
202, 203, 209, 219, 226,
227
leaves, 182
sex-organs, 184
sporophyte, 184, 185
stem, 182
crassinerva, Fig. 95
petrophila, Figs. 94, 95
Andreaeaceae, 161, 165
Andreaeales, 160, 166, 181
Androgynous receptacles,
Marchantiaceae, 613

681

682

INDEX

Aneimia, 335, 384, 385, 386, 387,
388, 389, 390, 420, 580, 636
antheridium, 385
hirsuta, Figs. 227,, 225
hirta, 385

phyllitidis, 636; Figs. 222, 226
Anelatereae, 73, 75, 614
Anemone, 574

Aneura, 2, 9, 14, 15, 16, 72, 85, ?>6,
88, 89, 92, 94, 96, 97, 98, 99,
109, 114, 121, 132, 157, 158,

274, 314, 564, 593, 595, 607,
617, 618
antheridia, 89
archegonia, 92, 93
embryo, 616
multifida, 12, 86, 95, 98; Fig. 45

gemmae, 86, 607, 618
palmata, 99 ; Fig. 48
pinguis, 95, 99 ; Fig. 45
pinnatifida, 87, 88, 90; Figs. 39,
40, 41
. Tjibodensis, 615
Aneuraceae, 615, 618
Angiopteridaceae, 632
Angiopterideae, 298, 583
Angiopteris, 271, 274, 276, 277, 279,
284, 286, 289, 290, 291, 292,
293, 297, 298, 299, 300, 304,
334, 340, 362, 366, 371, 582,
583, 602, 630, 631, 632, 634
leaf, 290, 291
stem-structure, 289
stipules, 290

vascular system, 290, 631, 632
evecta, 273, 291 ; Figs. 149, 157,

161, 163, 164, 167
Smithii, 633
Angiosperms, 291, 304, 558, 604,

605, 606
Anisogonium seramporense, 339
Annulariae, 586

Annulus, 165, 209, 210, 213, 294,
307, 343, 366, 371, 383, 392,
438, 584

Anogramme leptophylla, 308, 572
Antheridium,

Aneimia, 385

Anthoceros, 129, 130, 131

AzoUa, 399

Botrychium, 240

Cyatheaceae, 391

dehiscence, 53, 107, 199, 318

Dendroceros, 146

Equisetum, 447, 448

Funaria, 196, 197, 199

Gleichenia, 368, 635 ^

Hepaticae, 16

intermediate structures, 203

Jungermanniales, 73, 614

Lycopodium, 489

Marchantiaceae, 51, 614

Marsilia, 420

Muscineae, 10

Notothylas, 149, 150

Onoclea, 315

Ophioglossum, 236

Osmunda, 351, 352

Pallavicinia, 615

Pellia, 92

Pilularia, 421

Porella, 105, 106

Riccia, 31, 33

Salvinia, 398

Selaginella, 512, 513

Sphaerocarpus, 80

Sphagnum, 175, 176

thallose Hepaticae, 12
Figs. 5, IS, 16, 30, 7,7,, 35, 40, 52,
53, 67, 68, 80, 102, 103, 104,
125, 126, 128, 174, 195, 196,
217, 234, 244, 245, 246, 259,
260, 283, 295, 310
Antheridia, exogenous, 131
Antheridial receptacle,

Fimbriaria, 49

JVIarchantia, 53
Anthoceros, 14, 53, 120, 121, 122,
146, 147, 148, 149, 150, 151,
152, 153, 155, 156, 165, 179,

INDEX

6S3

187, 211, 227, 229, 301, 303,
359, 529, 564, 568, 570, 593,
594, 598, 599, 600, 601, 620,
621, 633, 642
antheridium, 129, 130
apical growth, 125
archegonium, 132, 133, 134
archesporium, 136
basal wall, 242
chloroplasts, 142, 158
dichotomy of thallus, 145
gametophyte, 123
germination of spores, 143, 144
mucilage-clefts, 125
sex-organs, 128
spore-development, 139
spore-division, 141
sporophyte, 134, 13 5, 136
stomata, 132
structure of thallus, 128
dichotomus, 145

fusiformis, 13, 123, 125, 128, 134,

139, 141, 142, 143, 144, 145,

149, 150, 450, 597; Figs- 64,

65, 66, 69, 73, 76, 77

laevis, 123, 133, 134, 139^ Hi,

143, 276, 349, 597
Pearsoni, 123, 129, 132, 133, 134,
138, 139, 140, 142, 143, 620,
621; Figs. 67, 70, 71, 72,

74, 75
phymatodes, 145

punctatus, 123
tuberosus, 145
Anthocerotaceae, 593, 608
Anthocerotales, 609, 622
Anthocerotes, 8, 10, 12, 13, 16, 74,
120, 148, 156, 158, 159, 227,
229, 231, 280, 300, 301, 302,
534, 565, 568, 592, 594, 595,
596
archegonium, 13
chloroplast, 13, 121
columella, 137
evolution of, 156

Anthocerotes — ■ Cont.

gametophyte, 13, 120

sexual organs, 121

sporophyte, 122
Antithetic alternation of generations,

569, 574
Apical cell, 81, 157

Anacrogynae, 89

Hepaticae, 15

Jungermanniaceae, 15, 102

Marchantiacece, 67

Muscineae, 9

Riccia, 38

root, 253, 266, 284, 325, 359

Sphaerocarpus, 82
Apical growth,

Amblystegium, 191

Aneura, 85

Anthoceros, 125

archegonium of Funaria, 202

Bryales, 190

embryo, 203

Jungermanniales, 72

Marchantiaceae, 47

Porella, 102, 103

prothallium, 314, 318

Sphagnum, 170

sporophyte of Mosses, 165

stem, 190, 459, 494
Apogamy, 233, 243, 308, 383, 570,

571, 573, 574, 634, 643
Apophysis, 207, 211, 213, 220, 224,

229, 600

Apospory, 233, 308, 309, 3^3, 57°,

571, 574, 634
Aquatic mosses, 160
Aquatic plants, 575
Archaeocalamites, 600 (see Astero-

calamites)
Archaeopterideae, 574
Archaeopteris, 580, 581, 582
Archaeopteris (Palaeopteris) , 579
Archangiopteris, 273, 295, 298, 300,

630, 632, 633
Henryi, Fig. 168

684

INDEX

Archegonial receptacle, 56, 57

Marchantiaceae, 48, 58, 613
Archcgoniala?, i, 121

fossil, 576

interrelationships, 592

Archegonium, i, 5, 6, 11, 17, 57,

113, 128, 132, 158, 164, 184,

203, 227, 279, 302, 309, 318,

319, 450, 451, 452, S32>, 544

Aneura, 92, 93, 94

Anthoceros, 132, 133, 134

Anthocerotes, 13

Azolla, 403

Botrychium, 240, 241

Dendroceros, 147

Funaria, 199, 200, 201

Gleichenia, 368

Haplomitrieae, loi

Hepaticae, 16

Hymenophyllaceae, 377

Isoetes, 543

Jungermanniales, 73, 74

Lycopodium, 490

Marattia, 280

Marchantiacea^, 46, 70

Mninum cuspidatum, 202

Notothylas, 150

Ophioglossum, 237, 238, 626

Osmunda, 353, 354

Pellia epiphylla, 94

Porella, 107, 108

Pteridophytes, 232, 596

Riccia, 29, 30, 31

Selaginella, 516

Spha?rocarpus, 76

Sphagnum, 177, 178, 181

thallosc Hepaticae, 12

Targionia, 53, 55
Archespermae, i

Archesporium, 5, 12, 13, 18, 21, 62,
80, 95, III, 122, 135, 136,

137, 138, 151, 165, 179, 185,

205, 207, 209, 214, 254, 255,

256, 269, 272, 293, 301, 307,
342, 474, 500, 531

Archidium, 166, 185, 214, 228
spore-formation, 187
spores, 185, 187
sporophyte, 186
Ravenelii, Fig. 96
Areolcs, 515, 541
Ascomycetes, 562
Aspidium, 395
falcatum, 309
filix-mas, 314, 345 (var. crista-

tum), 309
spinulosum. Fig. 230
Asplenium, 395
bulbiferum, 310
esculentum, Fig. 171
filix-fcemina. Fig, 231
nidus, 394, 624
Assimilating tissue, 122, 165, 227,

229, 465, 568, 594, 595
Astelic structure, 464
Asterocalamites, 586, 587 (Archaeo-

calamites)
Asterophylliteae, 586
Asterotheca, 582, 583
Astroporae, 59, 614
Athyrium filix-fcemina, 314 (var.

clarissima) 309
Atrichum, 164

undulatum, 161
Azolla, 233, 396, 398, 400, 409, 417,
603, 637
antheridium, 399
archegonium, 403
embryo, 405
female prothallium, 400, 401,

402
leaf, 409, 410
primary root, 406
roots, 411, 412
sporangium, 412, 414
sporocarp, 412
stem-apex, 406
stem-structure, 411
stomata, 411
Caroliniana, 402, 405, 412

INDEX

685

Azolla — Cont.

filiculoides, 405, 410; Figs. 235,
236, 237, 239, 240, 241, 242

Barbula fallax, Fig. 119
unguiculata, 623

Bast fibres, 464

Bazzania, 119

Begonia, 574

Bellincinioideae, 119

Blasia, 9, 12, 14, 72, 74, 99, 158
gemmae, 100
pusilla, 90; Fig. 41

Blepharoplast, 51, 52, 279, 316, 421,
422, 449, 608, 609, 625

Blepharoplastoid, 421

Blyttia, 618 — (see also Pallavicinia)

Blyttiaceae, 615, 618

Boschia, 42, 59, 60, 611, 614

Botrychium, 233, 235, 237, 238,
245, 249, 258, 272, 273,
277, 284, 285, 293, 295,
300, 303, 346, 359, 364,

365, 440, 554, 561, 564,
580, 582, 583, 602, 626,
628, 629, 634, 643

antheridium, 240

apical growth of stem, 262

archegonium, 240

cotyledon, 243, 244

development of first root, 244

embryo, 242, 243, 628

gametophyte, 239, 626

leaf, 264

root, 259, 266

secondary thickening, 262

sex-organs, 239

sieve-tubes, 266

spermatozoids, 240

sporangiophore, 259

sporangium, 268, 269

tracheids in prothallium, 243

vascular bundle of stem, 244

vascular bundles, 261, 265

venation of leaf, 259

Botrichium — Cont.

lunaria, 238, 245, 264, 267, 268,

269, 580, 626; Fig. 141
obliquum, 628
rutaefolium, 262, 270
simplex, 258, 259, 261, 266, 268;

Fig. 141
ternatum, 261, 264, 266, 267, 268;

Fig. 141
Virginianum, 234, 259, 261, 262,
267, 268, 269, 271, 300, 302,
304, 308, 366, 602, 626;
Figs. 126, 127, 128, 129, 130,
141, 142, 144, 145, 146, 147,
148
Bowmanites, 587
Branching,

Acrogynae, 14, 117, 619
Lycopodium, 494
Porella, 10 1
prothallium, 374
root, 499
stem, 497
Brown Algae, 607, 608
Bryales, 70, 161, 165, 166, 181, 182,
183, 185, 188, 213, 216, 220,
226, 228, 305, 594, 595, 600,
622, 623
apical growth, 190
branching, 193, 194
classification, 214
gametophyte, 188
germination of spores, 188
peristome, 220
stem-structure, 194
Bryineae, 184, 185, 186, 191, 205
^ Bryophyllum, 574
Bryophytes, i, 3, 4, 5, 8, 121, 229,
230, 257, 301, 321, 490, 563,
566, 572, 575
effect of drought, 571
gametophyte, 533
relation to Pteridophytes, 574
Bryoziphion, 217
Bryum argenteum, 623

686

INDEX

Budding, i6i, 560
adventitious, 574
adventitious of gametophyte,

277, 350
from roots, 339
sporophyte, 310
Buds, 233, 307, 308

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