same succession of tissues may be recognised, as has been
already described in the transverse section (III.) Starting
from the outside, they will be as follows : —
1. Epidermis "i these are hardly to be distinguished one
2. Outer cortex J from another : the cells of both are pros-
enchymatous, and thick-walled, and show a gradual transition
to—
3. The inner cortex, in which the walls are thinner, and
the form of the cells parenchymatous.
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154 PRACTICAL BOTANY
4. The lacunar tissue, the cells of which are elongated in a
radial direction.
5. The pericycle, consisting of elongated parenchymatous
cells, with cellulose walls, and often containing chlorophyll.
6. The phloem, the most prominent elements of which are
long narrow elements with cellulose walls and sparing con-
tents : these are regarded as the representatives of the siere-
tubes.
7. The zyiem, the most prominent elements of which are
spiral and scalariform tracheides, similar to those to be
described below as composing the xylem of the bundle in the
Ferns.
Observe the general arrangement of the stem, leaves, and
ligules.
In the lower part of the sections a mature sporangium may
be found in the axil of each leaf. The sporangium may have
lost its spores partially or entirely during the preparation of the
sections. It will consist of—
a. A short massive stalk.
b. A wall inclosing the central cavity : the wall will be found
under a high power to consist of three layers of cells —
i. The outer consisting of thick-walled cells, more or less
elongated radially.
ii. A layer of small, compressed cells.
iii. A layer of thin-walled cells, elongated radially : this is
the tapetum, which is here persistent until the spores are ripe.
Surrounded by the wall will be found —
c. Spores of two sorts, contained in different sporangia —
i. Microspores of relatively small size : these will be found
in large numbers in certain sporangia, which will accordingly
be recognized as microsporangia. When ripe they may be still
seen to cohere in groups of four : each spore is a single cell
with a brown wall.
ii. Macrospores of relatively large size : four only of these
will be found inclosed in a single sporangium, which is accord-
ingly termed a macrosporangium. Each spore consists of a
thick wall, with numerous external projections, surrounding a
large cavity filled with protoplasm, &c.
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SELAGINELLA GAMETOPHYTE 155
THE GAMETOPHYTE OR OOPHYTE
VI. Spores of both kinds may be obtained free by drying
branches which bear sporangia on sheets of paper. Pick out
the macrospores, and mount them in olive-oil : dissect off the
brittle outer coat of the spore with needles, and examine under
a high power. It will be seen that the chief contents of the
ripe spore are a protoplasmic matrix inclosing oil-globules and
aleurone-grains, while traces of the cells of the prothallitun may
be recognized even in these preparations.
If plenty of spores are to be had, embed a quantity of them,
and to cut sections, mounting them in glycerine. Observe —
1. The character of the wall, consisting of—
a. An outer thick, yellow exospore.
b. An inner thin endospore.
2. The contents as above described : the natural position
of the cellular tissue of the prothallitun may be seen to be at
the apex of the cavity of the spore.
VII. Spores of both kinds should be collected in considerable
quantity by drying on paper, and then be sown on moist soil
or sand, and left to germinate. In a few weeks young seedlings
will be seen with an erect axis, bearing small leaves. Note
that the axis of the seedling branches at an early period.
Remove some of these seedlings from the soil, and note the
monopodial branching of the root, and the macrospore still
attached laterally to the axis.
Longitudinal sections should be made through the young
seedling, so as to traverse also the macrospore attached to it :
in such sections it will be readily seen that a lateral outgrowth
(the foot) projects from the base of the axis into the cavity of
the macrospore : also that the latter is filled with a cellular
tissue of the prothallus, from which the nutritive substances
above noted in the mature macrospore will have been re-
moved.
A detailed description of work to be done on Lycofioctium
clavatum, as a homosporous Lycopod, is given in the larger
edition.
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B.— FILICINEiE
I. Homosporous Type
NEPHEODIUM FILIX-HAS (The Hale Shield Fern)
A.—MATURE SPOROPHYTE
I. — External Characters
I. Taking a well-grown plant of the common Male Fern in
summer, wash the soil away from the roots, and observe the
following external characters : —
A. The stem is oblique and ascending : it is not branched at
its apex : its surface is covered by the persistent bases of the
leares, which are densely covered by numerous brown scaly
hairs (palese or ramenta).
B. The leares, the most prominent of which are —
i. The fully developed green leaves of the current year : of
these the following parts may be recognized : —
a. A long almost cylindrical leaf-stalk, which is traversed by
two longitudinal, lateral ridges or reduced wings. This leaf-
stalk supports —
b. The numerous plnnee, which are arranged in two lateral
rows, corresponding in position to the lateral ridges above
mentioned : note that the arrangement of the nerves in the
segments of the pinnae is based upon repeated bifurcation of
the stronger nerves. On the under side of the pinnae will
frequently be found—
c. sort, which are roundish brown groups of small stalked
bodies (sporangia), covered by a kidney- shaped indusium.
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NEPHRODIUM SPOROPHYTE 157
ii. The bases of the leaves of previous years will be seen,
covering the lower part of the stock or stem externally :
observe that lateral buds are frequently to be found connected
with these, being attached to their ab-axial side, near to
their point of junction with the stem.
iii. Nearer the apex of the stem than the expanded leaves of
the current year, and completely covering it, are young leaves,
densely covered with ramenta: these, together with the axis,
constitute the apical bud. Note that the apex of each such
leaf is rolled up like a crozier (oiroinate vernation).
C. The roots are rather thin and brown, with transparent
apices : they are inserted on the bases of the leaves, close to
their junction with the stem : the branching of the roots is mono-
podia!, and their branches appear in acropetal succession.
II.— Anatomical Characters to be observed with the naked eye.
II. Having observed the above external characters, remove
the roots, keeping the transparent apices of the young roots, as
well as the thickest parts of the old roots : these should be
preserved in alcohol for further treatment.
III. Remove from the apical bud the large quantities of scaly
hairs (ramenta), so as to lay bare —
1. The young leaves, with their circinate vernation.
2. The broad apex of the stem with leaves in various stages
of development around it.
3. The young roots which will be found already present on
the bases of the young leaves.
4. The young buds which may be observed at a very early
stage on the posterior side of the leaves.
Starting from the older end of the stock, cut off successively
the persistent bases of the old leaves about half an inch above
their insertion on the stem. Observe the lateral bud borne by
some of the leaves on the ab-axial side of the leaf-stalk near its
base : observe also that the roots spring from the bases of the
leaves, close to their insertion on the stem.
If the specimen be a large one, with a stock 5 or 6 inches in
length, cut off about 2 inches of the older end of the stem
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158 PRACTICAL BOTANY
exposed as above, and boil it in dilute hydrochloric acid till the
parenchyma is soft : for further treatment of this see below.
Meanwhile smooth the cut end of the remainder Of the stock
with a razor, so that it may present an even surface of trans-
verse section, and observe —
a. The great irregularity of outline, due to the close crowd-
ing of the bases of the leaves.
b. The dark brown band of â– clerenchyma bordering the
periphery of the section.
c. The great bulk of the stem consisting of yellowish
parenchyma, with very bulky central pith,
d. Round the latter are a number of isolated, large vascular
bundles, forming an interrupted ring.
e. Outside these, and running out into the leaves, are
numerous smaller bundles of the leaf-trace, which appear to
be less regularly arranged.
IV. Divide the stock, including the apical bud, into two
symmetrical halves by cutting it in a median longitudinal
plane: smooth one of the cut surfaces with a razor, and
observe —
a. That the stem is of almost equal thickness throughout its
length, i.e. it is roughly cylindrical.
b. That its external conformation is very irregular by reason
of the closely crowded insertion of the leaves.
c. The bulky central pith as before.
d. The large vascular bundles (d above), which are not con-
tinuous in direct longitudinal lines, but form an interrupted
series.
e. The smaller bundles of the leaf-trace (e above), which
in some cases may be followed, after a little careful dissection
of the parenchyma which surrounds them, from one of the
larger bundles of the central system into the base of one of the
leaves.
Slice away carefully the external tissues of the posterior part
of the stock, so as to lay bare the central system of larger
bundles : it will then be seen that these form a continuous
network with large meshes, and that each mesh is opposite the
point of insertion of one of the leaves, hence it is called a
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NEPHRODIUM SPOROPHYTE 159
foliar sap. Observe also that the vascular bundles, which pass
out into any individual leaf, are given off from the margin of its
own mesh.
Confirm these observations by the dissection of the stock :
the parenchyma may be easily removed, leaving the vascular
system as a network of stronger bundles, which gives off nume-
Fig. 10. — Vascular skeleton prepared by maceration and dissection from the stem of
Nephrodiutn Filix mas. (After Reinke.) (a : x.)
rous weaker bundles from the margins of its meshes ; these
weaker bundles run out into the leaves.
By careful dissection a skeleton may be prepared similar
to that shown in Fig. 10.
Ill . — Microscopic Investigation,
V. Cut transverse sections of the stock of Nephrodiutn : it
is hardly to be expected that a transverse section of so bulky a
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160 PRACTICAL BOTANY
stem as this could be cut so uniformly thin that the structure of
all the tissues could be well seen ; it is better therefore to cut a
number of sections, each extending over a comparatively small
area, and to study the various tissues separately. Mount some
in glycerine or glycerine jelly, others in chlor-zinc-iodine.
Examine under a low power, and observe successively the
following tissues, starting from the periphery of the stem : —
a. An epidermis, consisting of a single, somewhat irregular
and ill-defined layer of cells, with dark brown outer walls :
their arrangement is disturbed at the point of insertion of the
scaly hairs, which appear as plates of cells one layer of cells in
thickness, rising obliquely from the epidermis. Beneath this
is —
b. The ground-tissue, which is differentiated as —
i. An outer narrow band of tissue, with rather thick, colour-
less, pitted walls, and cell-contents with much starch : there are
no intercellular spaces.
ii. A band of sclerenchyma with thick, yellow, lignified,
obviously stratified, and pitted walls, cell-contents as in (i.j,and
no intercellular spaces. This merges gradually into —
iii. The bulky central mass of ground-tissue, in which the
vascular bundles are embedded. It consists of cells with
comparatively thin, pitted, cellulose walls, protoplasmic contents
with much starch, and with intercellular spaces. Internal
glandular hairs are also found in the intercellular spaces.
c. The vascular bundles of elliptical outline: they are
embedded in the ground-tissue, and are sharply circumscribed
by a narrow, light brown layer of cells without intercellular
spaces : this is the bundle-sheath or endo dermis. Among the
tissues inclosed by this sheath, note that a large central mass
may be distinguished as consisting for the most part of
elements with large cavity, no cell-contents, and rather thick
walls with a peculiar marking : this is the xylem. Between
this and the bundle-sheath is a broad band of tissue with thin,
bright-looking walls, and with protoplasmic contents: this is
the phloem. Since the xylem is surrounded by the phloem,
this bundle is said to be of the concentric type.
In the sections treated with chlor-zinc-iodine note that the
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NEPHRODIUM— SPOROPHYTE 161
walls of the inner ground-tissue stain blue, and that starch is
found in the cells ; that the bundle-sheath appears browner
than before ; that the walls of the phloem stain blue (cellulose),
and the contents yellowish ; that the walls of the chief con-
stituents of the xylem stain yellow (lignified).
VI. As the vascular bundles of the leaf-stalk are better fitted
for minute observation, and are better types of the concentric
bundle of the Fern than those of the stem, cut thin transverse
sections of the lower part of the petiole. Having previously
noted with a low power that in their main features the tissues
resemble those above observed in the stem, examine the
structure of one vascular bundle under a high power, and
starting from the periphery of it, note successively —
1. The bundle-sheath or endodermls, a single layer of cells,
with yellowish walls, and yellow granular contents : there are
no intercellular spaces in this layer, nor in any of the tissue
surrounded by it.
2. The phloem-sheath or pericycle, which is a band of tissue
of varying thickness at different parts of the bundle, being thin
at the poles of the elliptical bundle, and thicker at the sides :
it consists of cells of roundish form, with cellulose walls, and
protoplasmic contents, and starch.
3. At the inner limit of the pericycle are found elements
with thick cellulose walls and narrow cavity, these constitute
the protophloem.
4. Internally lies the broad band of true phloem, which is
composed of two tissue-forms —
a. Sieve-tubes, which appear polygonal in the transverse
section, with thin cellulose walls which are lined by a
delicate protoplasmic membrane dotted with numerous
highly refractive granules.
b. Cells of the conjunctive parenchyma, with thin walls
and protoplasmic contents.
5. Centrally lies the xylem, in which also two constituents
may be recognized —
a. Tracheides, which appear polygonal in section, and
have large cavities, with no cell-contents : the walls
are thick and lignified, and show a peculiar structure
M
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i62 PRACTICAL BOTANY
which will be better understood on comparison of their
appearance in longitudinal sections.
b. Cosjunctire parenchyma with cellulose walls, and
protoplasmic contents with starch : these cells are
distributed evenly throughout the xylem, and also
form a band surrounding it completely.
VII. As a preliminary to the study of longitudinal sections,
separate some pieces of the vascular bundles of Pteris or
Nephroctium from the surrounding tissue, and warm them gently
in a test-tube with a little potassium chlorate and nitric acid,
till the elements of the bundle may be separated easily one
from another ; then stop the action by diluting with water, and
mount in water or glycerine. By preparing them in this way
the tracheides, &c, may be subjected to separate examina-
tion, and their form and structure may be more exactly made
out.
Apply the same process to the sclerenchyma, and observe
the form and marking of the walls of its constituent ele-
ments.
Cut longitudinal sections of the stem of the Male Fern : first
take radial sections of the peripheral tissues, and treat as
above : note —
1. The epidermis with scaly out-growths.
2. The subjacent ground tissue, and especially the scleren-
chyma consisting of cells of short prosenchymatous form,
with brown pitted walls, and cell-contents : note the gradual
transtion from sclerenchyma to —
3. The colourless ground tissue, with short parenchymatous
cells, and large intercellular spaces.
VIII. Cut longitudinal sections so as to pass tangentially
through the central network of bundles : treat some sections
with chlor-zinc-iodine, and mount others in glycerine. Note
the several tissues observed in the transverse sections, and they
will show here the same position relatively to one another. By
reason of the frequent splittings and fusions of this bundle-
system the several elements will appear contorted and twisted,
but this does not materially affect their general arrangement,
which will be seen under a high power as follows : —
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PTERIS— RHIZOME 163
A. In the xylem of the bundle —
a. The scalarlform tracheides, which are the main con-
stituents of the xylem : they are elongated, prosenchy-
matous elements, with ladder-like marking of the
lateral walls : this is due to the presence of regularly
arranged, transversely elongated, bordered pits. (Com-
pare those of the pine, p. 138.) Take especial notice
of the appearance of the lateral walls as seen in
longitudinal section, where two tracheides are con-
tiguous with one another, and compare them with
parts of the wall which adjoin.
b. Cells of the conjunctive parenchyma interspersed
among the tracheides.
c. Tracheides with spiral marking: these are the first-
formed wood, or protoxylem.
B. In the phloem observe —
a. The sieve-tubes, which are also elongated elements with
pointed ends ; the surfaces of the walls which separate con-
tiguous sieve-tubes are covered with numerous sieve-plates
(best seen in sections treated with chlor-zinc-iodine), to which
round, highly refractive granules adhere : these stain yellow
with chlor-zinc-iodine. Note also the irregular beaded appear-
ance of the walls when seen in longitudinal section.
b. Cells of the conjunctive parenchyma, interspered among
the sieve-tubes.
As the vascular bundles of the rhizome of Pteris the (common
Bracken) are more regularly typical of the concentric bundle of
the Fern than those of Nefihrodium, thin transverse sections
should also be prepared from the rhizome of this plant ; mount
some of the sections in glycerine, others in chlor-zinc-iodine ;
or these sections may be stained with hematoxylin and mounted
in Canada balsam.
First examine the whole section under a low power, and note
its oval form, the upper and lower surfaces being flattened. It
is composed of the following tissues : —
1. A peripheral band of brown sclerenchyma, outside which
is a scarcely distinguishable epidermis.
M 2
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164 PRACTICAL BOTANY
2. Colourless, parenchymatous ground-tisane, in which are
embedded successively the following : —
3. An outer series of relatively small, sharply circumscribed
vascular bundles, arranged in an irregular ring : one larger
bundle is usually to be found opposite the lower flattened
surface.
4. An incomplete ring of dark brown sclerenchyma, com-
posed of two parts which are usually distinct, viz. an upper
strongly curved portion, and smaller flat portion which is
nearer the lower surface : small isolated patches of brown
sclerenchyma may also be seen dotted about in the ground-
tissue.
5. A central series of bundles, usually two or three in
number, and of larger size : they may sometimes be found to be
connected at their margin into one irregular ring-like mass.
Examine the sclerenchyma under a high power, and note the
thick, brown, stratified walls : the cells contain a somewhat re-
duced protoplasmic body.
Examine also the parenchymatous ground-tissue, which
will be found to consist of cells with thin cellulose walls, and
mucilaginous protoplasmic contents, with much starch. Note
especially small pegs and rods, which appear as superficial out-
growths from the walls adjoining the intercellular spaces.
Select a single elliptical vascular bundle for detailed observa-
tion under a high power, and recognize —
1. The bundle-sheath or endodermis, which is a definite, but
narrow layer of cells, with brown coloured contents.
2. The phloem-sheath or pericycle, which is not quite so
definite a layer of deeper cells, with cellulose walls, and
plentiful protoplasm.
3. Within this is a band of phloem, which is wider at the
flattened sides of the bundle, but narrower at the two poles : it
consists of —
a. Sieve-tubes, which may be recognized by their large
cavity, sparing contents, and cellulose walls : note where two
sieve-tubes are contiguous that bright yellow granules may be
seen adhering to the wall : these indicate the position of the
sieve-plates.
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*>TfeRIS— RHIZOME 165
b. Parenchymatous cells, which fall under the general term
conjunctive parenchyma.
4. An elliptical area of xylem occupies the centre of the
bundle, it is composed of —
a. Tracheides, which are large and of circular or polygonal
outline, with highly refractive lignified walls, and no cell-
contents. Towards the poles of the elliptical area tracheides
of small size, and circular outline may be seen : these are the
protoxylem.
b. Conjunctive parenchyma, distributed irregularly among
the tracheides.
Longitudinal sections should also be cut, so as to traverse
the vascular bundles of the central series : they may be treated
as above directed. Note in these the thin-walled ground-
parenchyma, and the brown sclerenchyma ; the latter consists
of fibrous cells with peculiar crossed pita in their walls.
a. The bundle-sheath, or endodermis, consists of narrow
oblong cells with square ends, and with brown contents.
b The phloem-sheath, or pericycle, is composed of wider
oblong cells, with colourless protoplasic contents : the ends are
square or oblique.
c. The sieve-tubes appear as wide tubes, with pointed ends,
and cellulose walls : the surfaces of the walls which separate
contiguous sieve-tubes are covered with numerous sieve-plates
(best seen in sections treated with chlor-zinc-iodine), to which
round, highly refractive granules adhere : the sieve-tubes are in
fact essentially similar to those of Nephrodium (p. 163). Note
especially the irregular outline of the wall when seen in
longitudinal section : this will be best seen in sections which
have been cut so as to pass through the phloem in a plane
parallel to the flattened side of one of the larger bundles.
d. The scalariform tracheides, which are the main con-
stituents of the xylem : they are similar in all their main
characters to those of Nephrodium (see p.. 163), being elongated
and pointed, while the walls are marked by transversely-extended
bordered pits, arranged regularly so as to give the ladder-like
appearance ; but they differ from them in one point, for by a
careful examination of fine sections it may be ascertained that
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166 PRACTICAL BOTANY
the pit-membrane which remains permanently in Nephrodtum y
is often broken down on the oblique terminal walls in Pteris :
this is, however, exceptional for Ferns.
e. The conjunctive parenchyma, distributed among both
sieve-tubes and tracheides.
IX. From around the apical bud of a well-grown plant of the
Male Fern remove successively the bases of the leaves of previous
years, those of the current year, and finally the larger circinate
leaves, which would have unfolded in the following year. Care-
fully remove the smaller ones with a scalpel, and then with
forceps gradually pull off the large mass of brown scales, which
completely cover the extreme apex. With a stiff camel's-hair
brush remove the bases of these scales, together with the
youngest of them, which will still remain round the punctum
vegetationis : after this treatment it will be easy to observe with
a pocket lens —
1. The apical cone {punctum vegetationis) , a rounded papilla,
occupying a central and terminal position in the flattened apical
region.
2. The young leaves, situated round the apical cone, and
successively larger the further they are from the apex. Note
the circinate curvature which appears at an early period in their
development.