walls of the host plant assume a dark colour : they are for the
most part confined to the intercellular spaces, and especially
those round about the aecidia ; but it is stated that occasionally
they penetrate the cells of the host, and though this is not easy
to see, examples of it should be looked for. Turning to the
aecidium observe —

i. Its cup-like form.

2. The dense felt of hyphae at the base of it.

3. Immediately above this is the hymenium, a layer com-
posed of closely packed, parallel, rod-like cells (basidia),
arranged perpendicularly to the outer surface of the leaf.

4. The rows of spores, which have been successively ab-
stracted from the basidia : observe the hexagonal form, thickened
wall, and orange colour of the spores, and the way in which the
spores of contiguous rows fit together.

5. The peridlum, consisting of a single layer of cells en-
veloping the mass of spores : the form and arrangement of the



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234 PRACTICAL BOTANY

cells resemble that of the spores themselves though not so
regular : note the thickened and striated outer wall.

Returning to the spermogonia, observe —

i. The closely packed, parallel, rod-like hyphae converging to
the centre (sterigmata).

2. The minute oval bodies (spermatia) abstricted from them,
and escaping through the narrow pore on to the outer surface
of the leaf.

3. The brush of hyphae which protrude through the narrow
pore.

VI. It is known that the aecidium-spores of this fungus will
not infect the Barberry plant afresh, but will only germinate so
as to infect a Grass plant ; thus the fungus is an example of
" Hetercecism." The spores retain their germinating power
only for a short period.

Take some fresh spores from an aecidium, and place them in
a drop of water on the surface of a fresh leaf of some Gramin-
eous plant : after keeping it in moist air for about 48 — 60 hours,
strip off a part of the epidermis, or better, cut tangential sec-
tions of that part on which the spores have been placed : mount
in water with the outer surface of the epidermis uppermost,
and examine under a medium power : observe that the secidinm
■pores have produced tubular hyphse, which make their way,
through the pores of the stomata, into the tissues of the Grass
plant.

VII. Infect a Grass plant with secidinm spores and keep it
in a moist atmosphere : in about a week reddish swellings will
appear about the points infected, and the epidermis will be
ruptured.

Cut transverse sections so as to traverse one of these ruptured
spots : mount in water, and observe under a medium power :
note —

1. The branched mycelium ramifying in the tissue of the
Grass.

2. The ruptured epidermis.

3. The closely packed uredo-spores of simple oval form,
borne on thin pedicels (basidia). Observe further the exospore,
rough with small outgrowths : the endospore, with four



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PUCCINIA 235



germinal pores, arranged equatorially ; here the inner wall
is wanting : note the protoplasmic contents with reddish
granules.

The infected Grass plants which have produced uredo-spores
should be kept till the autumn, when the patches which before
produced uredo-spores only will, on investigation as above
directed, be found to bear teleutospores intermixed with them,
and finally to assume the winter condition of containing teleuto-
spores or winter-spores only, in which condition the winter is
passed : with this stage the study of the Fungus, as above
directed, was begun.



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236 PRACTICAL BOTANY



D. CLEISTOCARPOUS ASCOMYCETES
EUBOTIUM ASPERGILLUS GLAUCUS

1. Keep a slice of dry bread under a bell-glass, until it
becomes mouldy. Even a superficial examination of it will
show in most cases that more than one kind of Mould is present.
Among the rest the most prominent will probably be one which
bears roundish, white or pale green heads closely aggregated,
and borne on stalks of about one-sixteenth of an inch in length :
this is the conidial form of Eurotium Aspergillus glaucus,
and the branches bearing the heads are styled the conidio-
phores.

% Shake some of these gently with the point of a needle : numer-
ous minute powdery bodies (the conidia) will be liberated, and
will float away as a fine cloud.

II. From a pure patch of this green Mould remove a small
portion with a needle, avoiding mechanical roughness as much
as possible : lay it on a slide, moisten with a single drop of
alcohol, then add water, and cover gently with a cover-slip.
Examine it under a low power, and observe —

i. The stalked conidiophores, with large, mop-like heads.

2. Attached to these, the colourless tangled mycelium from
which they spring.

3. The innumerable detached conidia which will be found
thickly distributed throughout the preparation.

Having selected one of the largest of the conidiophores,
examine it in detail under a high power, noting especially —

1. The robust stalk, usually without septa : its wall is clearly
defined, and the protoplasmic contents granular and vacuo-
lated.



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EUROTIUM 237



2. The transversely septate, branched mycelium, from which
the conidiophores arise as vertically growing branches, usually
from a point immediately behind one of the septa : in this as
in other cases of branching of the mycelium, the branch grows
out at right angles from the hypha which bears it.

3. The swollen spherical head of the conidiophore, with its
conidia in radiating rows inserted upon it. Examine carefully
the way in which the conidia are produced, noting —

a. The aterigmata, which are peg-like radiating outgrowths
from the head of the conidiophore.

b. The series of conidia, in successive stages of development,
which have been successively formed by abatriction from the
sterigmata.

c. The oval form, and spiny surface of the mature conidium.
In order to observe the successive stages of development of

the conidiophore, small portions of the Fungus should be taken
from the white patches, where the growth is younger, and be
treated as before. In these specimens the following points are
to be observed —

1. The conidiophore as a club-shaped thick erect hypha.

2. The swelling of the head, though it at first remains quite
smooth.

3. Minute papillar outgrowths appear on the surface of the
head— these are the young sterigmata.

4. The sterigmata elongate, and become attenuated at the
tips.

5. The successive stages of abstriction of the conidia from the
apices of the sterigmata.

III. In order to trace the germination of the conidia, they
should be cultivated under microscopic observation on the
slide. For this purpose a moist chamber is to be prepared as
directed in Appendix A. It will be necessary to take certain
precautions to reduce the probability of access of foreign spores
to a minimum, and so insure as nearly as possible a pure
culture. Prepare a nutritive solution by boiling French plums
in water : this decoction is to be used very dilute, and is to be
boiled immediately before starting the culture, so as to kill
any foreign spores which may be already present : with the



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238 PRACTICAL BOTANY

same object, the glass slide, cover-slip, and needles are all to be
heated in a spirit-lamp, and the porous pad for the moist
chamber is to be well boiled in water.

Having made these preparations, place a single drop of the
dilute, sterilized decoction on the cover-slip : then with a
needle, moistened with the sterilized fluid, remove from as pure
a tuft of Eurotium as can be found a small number of conidia,
and place them in the single drop on the cover-slip : examine
under a low power to see that the number of conidia is small,
then quickly invert the cover-slip and place it over the round
hole punched in the porous pad. Keep the preparation thus
made under a bell-glass, and observe it from time to time under
the microscope : if the culture be successful, the successive
stages of germination and of further development of the Mould
may be watched in detail.

IV. The perithecla, and the archlcarps (female organs)
which give rise to them, are to be sought for on a mycelium
which has already produced mature conidia : the ripe perithecia
{Eurotium fruits) may be readily recognized in old cultures on
dry bread, as minute yellowish spherical bodies, easily distin-
guished by the naked eye.

A. Remove a small piece of mycelium which has already
borne mature conidiophores, and is thus likely to bear young
archlcarps: moisten it with alcohol, and then wash off in a
watch-glass in water as many of the conidia as possible : tease
it out with needles, and, mounting in water, examine under a
high power. Observe —

i. That the same mycelium which bears the conidiophores
also produces relatively thin whip-like branches, with highly
refractive contents.

2. That some of these branches become coiled, at first
loosely, but later in a tightly packed spiral of four or five coils,
and consisting of several cells : these spirals are the archlcarps.

3. That first one, and subsequently several hyphal branches
appear below the closely coiled archicarp, forming an invest-
ment round it : the first formed branch is called the pollin-
odlum (male organ), and comes in close contact with the apex
of the coiled archicarp.



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EUROTIUM 239



B. From a culture of some six weeks' duration on dry bread
pick off with a needle some of the minute spherical perithecia :
mount them in water and examine under a low power; ob-
serve —

1. The round or oval form of the perithecia.

2. That they are composed of a small-celled pseudo-paren-
chymatous tissue.

3. Their yellow colour.

4. Their insertion, each being borne on a single filament of
mycelium.

The yellow colour is due to an oily substance, which is
soluble in alcohol, or in potash solution.

Treat some perithecia with a weak potash solution, mount
them in glycerine, and examine under a high power : note —

1. The wall of the perithecium, consisting of a single layer
of somewhat flattened cells.

2. The cavity surrounded by that wall, filled with bodies of
oval form — the asci.

In order to be able to examine the asci in detail, mount fresh
perithecia in glycerine, press with a needle on the cover-slip so
as to burst them, and note —

1. The ruptured wall, as before.

2. The oval asci, each of which contains eight aacospores,
of oval shape when young, and biconvex-lens shaped when
mature.

3. Other cells may also be found which belong to the pseudo-
parenchyma ; this is derived by ingrowth from the wall of the
perithecium, and is only to be found in young perithecia : at the
period of maturity it is completely absorbed.

Among the Moulds which appear with constancy on bread
kept under a bell-glass, as also on other organic bodies, is
Penicillium : it may be readily distinguished from Aspergillus
by its lower growth, more velvet-like appearance, and blue-green
colour, while the latter shows a higher growth, so that the
individual conidiophores may be seen with the naked eye, and
its colour is an olive-green.

Remove a small piece from a pure patch of Penicillium which
has been recognized by the above characters : tease it out with



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240 PRACTICAL BOTANY



needles, then moisten it with alcohol, and mount in water.
Examine it under a high power, and observe the branched,
septate mycelium, which frequently forms a very dense mat :
this is especially the case if it be grown on Pasteur's solution
with sugar. Note that certain branches, which grew up from
the substratum, end in a brush of closely arranged parallel
branches, and that each branch is terminated by a string of
conidia : these are formed by basipetal abstriction, in the same
way as in Aspergillus.

The conidia may be germinated in the same way as those of
Aspergillus, and with suitable precautions pure cultures may be
grown on various nutritive substrata.



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PYTHIUM 241



IV. PERONOSPORE^E
PYTHIUM DE BAETANUM

I. Sow seeds of the common garden Cress {I^pidium sativum)
thickly in a flower-pot : cover it over with a glass plate, and
keep it well watered, so that the young seedlings grow up in an
atmosphere saturated with water. After a few days the head
of some of the seedlings may be seen to have bent over, owing
to insufficient support of the stem : examination will show that
the curvature is a sharp one, so that it is not due to general
weakness : further that the stem is thin and flabby at the point
of curvature : while fungal filaments may be observed in close
contact with the stem at that' point, and it is this Fungus
{Pythium de Baryanum) which is the cause of the disease
termed by gardeners " damping off": it is of common occurrence
in propagating pits which are kept too warm and moist.

If the Cress cultures be kept damp for some days longer, a
thick felt of hyphae will be formed, which will bind the seedlings
together : and finally the disorganization, which usually begins
near the base of the hypocotyledonary stem, will spread through-
out the seedlings, causing complete rotting.

II. Mount part of a stem of one of the collapsed seedlings in
water, and examine under a low power : observe —

1. That the tissues show an abnormal appearance at the
point of curvature, their colour is yellowish, and the individual
cells show signs of having lost their turgidity.

2. That numerous colourless branched hyphse extend along
the surface of the seedling, being most numerous at the point
of curvature, and less frequent further up.

R



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242 PRACTICAL BOTANY



III. Tease out a portion of the infected part, as well as of the
healthy part above, with needles in water, and mount so that a
part at least of the epidermis' shall be seen in external surface
view ; or sections may be cut, the infected part being held
between pieces of pith : in such preparations. observe —

1. The healthy part of the epidermis with elongated cells, and
occasional stomata.

2. The branched, highly refractive, and for the most part non-
septate hyphue, running with an irregular, but mostly longitudinal
course along the outer surface.

3. Mark especially the points of entry of the Fungus into the
host-plant : this may be either —

a. By perforation of the outer wall of a cell of the epidermis ;
and this is by far the more common : or —

b. By passage of the hypha through the pore of a stoma : this
is the less common mode.

4. Trace the further course of the hypha through the trans-
parent tissues of the host-plant, noting the rarity, or complete
absence of septa.

IV. Place an infected seedling in fresh water, in a flat watch-
glass, and examine it at intervals for a day or two under a low
power. Many of the filaments will be seen to form swellings at
certain points, which assume a spherical form, are filled with
granular protoplasm, and are divided off by a septum from the
parent filament, while the thin outer wall assumes a darker
colour : these swollen bodies are the asexual reproductive
organs, or resting conidia. Two types are to be dis-
tinguished —

1. Terminal conidia, at the ends of the filaments.

2. Interstitial conidia, which may appear at any other point
on the filament

It is characteristic of this species that the hypha should be
partially or completely emptied of protoplasm for a short dis-
tance below the conidium.

These conidia are capable of withstanding drought, or a
temperature below freezing, without losing their vitality.

V. From a culture containing numerous conidia, separate a
small portion, and expose it in a watch-glass to a relatively con-



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PYTHIUM 243



siderable bulk of fresh water : examine the culture at intervals
under a low power. Some of the conidia will be seen to
germinate by the formation of tubular hyphae similar to those
which produced them.

VI. Continue at intervals the observation of those cultures
which have already produced conidia : the formation of the
sexual organs will frequently be seen to succeed that of the
conidia.

a. The oogonium resembles at first the conidium in being
spherical, and about of equal size with it, and is partitioned off
by a septum ; a central spherical mass of protoplasm (the
ovum) is to be recognized.

b. The antheridium arises as a branch, either from the same
filament as the oogonium, or from another : its apex is cut o#
by a septum, and it comes in close contact with the oogonium :
a cylindrical process from it passes through the wall of the
oogonium, and gains access to the ovum.

c. In more mature specimens the oogonium contains a single
round, distinctly walled cell (the oospore), which lies freely
within it.

Observations may also be made on the Potato Fungus (Phyto-
phthora infestans) the mycelium of which permeates the tissues
of the Potato plant, while its branched conidiophores project
through the stomata.



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244 PRACTICAL BOTANY



V. MUCORINE^E
MUCOR MUCEDO, Free

1. If a slice of bread be soaked in water, and kept under a
bell-glass, various moulds will make their appearance upon it :
about the fourth or fifth day there will be seen a mould, which
at first appears white and flocculent, producing long unbranched
stalks, which terminate in round heads, white at first, and sub-
sequently becoming black : this will be Mucor Mucedo. It may
also be obtained on horse-dung kept under a bell-glass, and on
various other substrata.

II. Remove a very small piece of the bread bearing the
mould, and tease it out gently in water : mount and examine
under a low power : note —

i. Relatively thick, non-septate hyphae, which ramify in the
substance of the bread.

2. Relatively thin branches, which are produced from the
thick ones, and themselves, branching repeatedly, produce a very
extensive system of minute fibrils.

3. Hyphae similar to (1), which however grow erect in the air
(gonidophores), each bearing at its summit one spherical spor-
angium : this will certainly have been damaged in the process
of preparation.

III. Cut off a number of mature sporangia with scissors
from the flocculent growth, treating them very gently, so as to
avoid damage : mount them in alcohol, and examine them
quickly under a low power : observe —

1. The cylindrical gonldiophores, terminated by —

2. The spherical and dark-coloured sporangium; with its



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MUCOR 245



dense contents, and its very thin limiting wall, often bearing
small radiating projections.

3. Towards the point of attachment to the stalk a clearer
space may be recognized in the contents ; this indicates the
position of the columella.

Add a drop of water, and draw it under the cover-slip with
blotting-paper, watching the effect upon the sporangia : as the
water gains access to the sporangia, they burst suddenly, and
the wall may be torn to fragments so minute that it cannot be
recognized again. Meanwhile the contents, the swelling of
which caused the rupture, gradually distend, and may be
recognized as consisting of—

4. Numerous oval spores, with smooth walls.

5. An intermediate mucilaginous substance which is capable
of swelling, and thus effects not only the bursting of the sporan-
gium, but also the dispersal of the spores.

6. After the swelling and dispersal of the spores are complete,
there will be seen remaining a spheroidal body (the columella),
which is the distended septum of separation of the sporangium
from the gonidiophore : round its base the remains of the wall
of the sporangium may often be traced as a ragged fringe.

IV. With similar precautions to those taken in the case of the
spores of Eurotium Aspergillus (p. 237), sow spores of Mucor
in a drop of a sterilized decoction of horse-dung, or of French
plums, or other suitable solution : the swelling and germination
of the spores and the formation of the branched, non-septate
mycelium are to be watched ; and drawings may with ad-
vantage be made at intervals, so as to record the progress of
the cultures.



SPORODINIA GEANDIS, Link

V. Mucor mucedo also reproduces itself by means of zygo-
spores, which are of such size that they may be detected with
the naked eye as black bodies which project slightly from the
substratum ; but they are not of constant occurrence, and may
frequently be looked for in vain. Accordingly it will be found



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246 PRACTICAL BOTANY

more convenient and successful to study the development and
structure of the zygospores in an allied form, in which they are
produced in profusion, viz. in Sporodinia grandis, Link. (»
Syzygites megalocarpus % Ehr.).

Sporodinia is a fungus which may frequently be found in
autumn, growing parasitically on many of the larger, fleshy
Hymenomycetes, especially on Russula, or Boletus : it appears
as a greyish or brown flocculent growth, and the zygospores are
of such a size that they can readily be seen as reddish-brown
bodies with the naked eye. While a part of the mycelium
ramifies in the tissue of the host, the zygospores are borne on
aerial branches : they may thus be easily recognized as brown
bodies, visible to the naked eye.

Tease out a small piece of the flocculent mycelium gently in
water : examine under a low power, and observe —

i. The branched hyphee, which are light-coloured, and rarely
septate when young, but assume a brown colour, and form
numerous transverse septa at irregular intervals as they grow
old.

2. The large brown zygospores, each supported by two
thicker, club-shaped hyphae {Syzygites form).

3. The relatively small sporangia borne on branched gonidio-
phores, and having a structure similar to those of Mucor
{Sporodinia form).

Compare a number of zygospores in various stages of deve-
lopment, and observe in them the following points —

1. The swelling of two neighbouring mycelial filaments
(suspensors), and their assumption of a position with their two
swollen ends opposite one another.

2. The formation of transverse septa cutting off the apical
part of each suspensor, thus forming the two gametes.

3. The two gametes in close contact with one another, while
the walls at the point of contact are gradually absorbed, the
absorption beginning at the central point : the two protoplasmic
bodies thus coalesce to form the zygote or zygospore.

4. The increase in size of the zygospore, its contents becoming
dense and oily, while the wall at the period of maturity consists
of the following successive layers —



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SPORODINIA 247



a. The primary membrane of the gametes, which remains
thin, but persistent as an external covering.

b. The epispore, which is a dark-coloured firm or brittle
layer with hemispherical wart-like outgrowths from the surface.

c. The endospore, which is thicker and more transparent.
Note how numerous though irregular are the septa in

the mycelium which has produced zygospores.

It is not an uncommon thing in Sporodinia to find that the
two gametes may not come in contact, and no zygote be found ;
but still each gamete may develop into a body resembling a
zygospore in the character of the wall, the contents, and in the
mode of germination. These bodies are called ayygospores,



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by Google



APPENDIX A.



The following list of reagents is not intended to be an
exhaustive catalogue of the various substances in use in the
Botanical Laboratory : it includes, however, those reagents
which are considered to be of the greatest importance, in
elementary teaching, together with notes on their proper pre-
paration, and uses.

Acetate of Potash. A strong solution in water is used as a
mounting medium for preparations of green parts of plants :
in this solution they retain^their green colour for a long time.
Aluminium acetate may also be used for the same purpose.

Acetic Acid. This is usually used as a dilute solution in
water (i per cent.) : it dissolves calcium carbonate with evolu-
tion of bubbles of C0 2 : it brings out the nuclei very clearly,
and with this object in view it is used with methyl-green : it
may also be employed as a corrective after treatment of a pre-
paration with potash, if the tissues have become too transparent.
Glacial acetic acid is also sometimes used in the preparation of
the apex of Fucus.

Alcohol is of universal use as a solvent, precipitant, and
hardening agent. Absolute alcohol is the best, but for most
ordinary work strong methylated spirit will do. It dissolves
chlorophyll and other colouring- matters, resins, ethereal oils,