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ALBERT R. MANN
LIBRARY

AT

CORNELL UNIVERSITY

3 1924 057 348

165

Cornell University

Library

The original of this book is in
the Cornell University Library.

There are no known copyright restrictions in
the United States on the use of the text.

http://www.archive.org/details/cu31924057348165

THE

NATURAL HISTORY OF PLANTS

THEIR FORMS, GROWTH,
REPRODUCTION, AND DISTRIBUTION

FROM THE GERMAN OF

ANTON KERNER von MARILAUN

PROFESSOR OF BOTANY IN THE UNIVERSITY OF VIENNA

BY

F. W. OLIVER, M.A,, D.Sc.

QUAIN PROFESSOR OF BOTANY IN UNIVERSITY COLLEGE, LONDON

WITH THE ASSISTANCE OF

MARIAN BUSK, BSc. anp MARY F. EWART, BSc.

WITH ABOUT 1000 ORIGINAL WOODCUT ILLUSTRATIONS AND SIXTEEN PLATES IN COLOURS

HALF-VOLUME IV.

NEW YORK

HENRY HOLT AND COMPANY
1895

A. g05 se

CONTENTS OF HALF-VOLUME IV.

LIST OF ILLUSTRATIONS.

PuateE XV. FRONDOSE AND FRutIcOosE LICHENS, - - -
» XVI. Evcatyprus GRovE AND GRASS-TREES IN AUSTRALIA,

Illustrations in the Text—Fig. 357 to Fig. 482.

THE HISTORY OF SPECIES (Continued),

2, Alteration in the Form of Species (Continued)—
The Influence of Mutilation on the Form of Plants, - - -
Alteration of Form by Parasitic Fungi, -
Alteration of Form by Gall-producing Insects,- - - -
The Genesis of New Forms as a result of Crossing,

3. The Origin of Species—
The Genesis of New Species, - BR So us
Derivation of Existing Species, ‘- - : 2
The Subdivisions of the Vegetable Kingdom, - 5

4, The Distribution of Species—

The Distribution of Species by Offshoots, -
The Dispersion of Species by Means of Fruits and Seeds,- —-
Limits of Distribution, 3 = =
Plant Communities and Floras, - < s

5. The Extinction of Species, - - e.g

to face

PAGE

694
730

514
518
527
554

576
595
600

790
833
878
885

899

ERRATA.

Vou. I.

Plate I., fly-sheet, q, for Cress read Summer Savory (Satureja hortensis).
p. 336, line 15, for Daffodil read Lily.
p. 547, line 16, for 16°1° read — 16°1°.
p. 663, line 27, for repens read reptans.
p. 685, line 24, delete cownter-.
» line 28, for clockwise read cownter-clockwise.

Vou. II.

Pp. 69, line 4, for Lycopodiacece read Lycopodiales.
p. 89, line 12, for 213’ and 213 ? read 213? and 213 *,
p. 120, line 7 from bottom, for acer read acris.

p. 121, line 1, for Leguminous read Oruciferous.
p. 280, line 2 from bottom, for Lentibulacee read Lentibularincee.
p. 612, line 11 from the bottom, for calcination read calcification.
p. 633, line 1, after though insert not.
p. 641, line 12, for not read -net.
p- 648, line 7, for the read some.
» line 16, for allimetes read akinetes.
p. 696, line 25 from bottom, for Antherocerotacee read Anthocerotacew.
p. 698, line 1, for Antherocerot read Anth ti
p. 704, line 14, for Pteridophyte read Pteridophyta.

INFLUENCE OF THE SUBSTRATUM. 497

Under these circumstances it is a matter of indifference whether 10 per cent
or only traces of lime or silica can be demonstrated in the soil, and the hypothesis
that plant-species which grow on limestone fail to grow on slate because they
are not able to supply their need of calcium, or that the plants growing on slate
cannot flourish on limestone mountains because they cannot obtain the necessary
amount of silica, must be abandoned, as well as the assumption that these substances.
when absorbed as food serve as a stimulus to change of form.

I strongly supported this latter hypothesis at the time, and thought I should be
able to strengthen and confirm it by careful cultural experiments. Seeds of several
species which demand lime were sown in soil containing hardly perceptible quanti-
ties of lime, and the seedlings were watered with water devoid of calcium; in
another place seeds of species demanding a silica-containing substratum were placed
in soil which contained much limestone, and the seedlings were watered with lime-
water. At first it seemed as if an alteration of form had actually taken place in

-some individuals. But this was a mistake, or rather, the alteration only consisted
in the greater or less luxuriance of the foliage, lengthening or shortening of the
stem, abundant or scanty development of flowers and the like. But no actual
change of form which would be retained by their descendants could be obtained.
The species of plants accustomed to lime, grown on a soil devoid of lime, presented
a miserable appearance, with scanty flowers which ripened only a few seeds,
whilst the silica-demanding species grown on lime-containing soil soon withered
and died without flowering at all. The change of form, indeed the actual inter-
change I had anticipated between the closely allied species which grow on the
two rocky substrata in a state of nature, did not occur at all.

If we still take the case of siliceous and calcareous plants, and regard the soil
as the source of free inorganic substances which influence the plants, we are
forced to assume that greater quantities of one substance will be injurious to one
or other of them. The absorbent cells have the capacity of choosing between the
substances at their disposal, but this capacity has a definite limit in every species.
The cells can absorb as much as they require from a very weak solution of
common salt, soda, gypsum, calcium bicarbonate, &., but a concentrated solution
of these salts may injure and destroy their structure and function. If it
is allowed to act for any length of time on the cells whose function is to absorb.
inorganic nutriment, the death of the whole plant will inevitably result. If the
Moss which grows on blocks of granite is ‘watered with a saturated solution of
gypsum; if the soil into which our Meadow-grasses send their roots is watered
with a saturated solution of common salt; or if the humus in which the plants of an
upland moor grow is mixed with sodium carbonate or calcium bicarbonate, the plants
invariably perish, and the same mineral substances, which in a very weak solution
are needful, or at any rate harmless, become poisonous when the solutions are
concentrated. The fact that one species of plant prefers this and another that
mineral substance (see vol. i. p. 73), however, renders it probable that the injurious

effect of materials in large quantity in the soil varies, that a large quantity of
Vou. IT. 82

498 DEPENDENCE OF PLANT FORM ON SOIL AND CLIMATE.

common salt would be injurious to one species, and an abundance of sodium or
potassium salts to another. From the present standpoint of our knowledge
concerning the absorption of inorganic materials by plants, therefore, Unger’s
classification, especially the expressions silica-demanding and silica-preferring, is no
longer suitable, and it would be more to the purpose to speak of plants which are
injured by lime, potash, &c.

The difference in the vegetation on the closely adjoining limestone and slate
mountains met with in so many places in the Al,s, and so well seen in the neigh-
bourhood of Kitzbithel, where the climatic influences on the two ranges are identical,
can be accounted for most satisfactorily in the following way. Plant-species which
demand or prefer a siliceous soil are absent from limestone mountains wherever
their roots would be exposed to more free lime than is beneficial; if present they
would be weakened, and thus vanquished in the struggle with their fellows, to
whom the larger quantity of lime is harmless, and they would eventually perish.
These plants flourish luxuriantly, however, on slate mountains, because there the
soil does not contain an injurious amount of lime. The absence of species, demand-
ing or preferring lime, from slate mountains can be explained in the same way.
When seeds are brought thither by the wind from the neighbouring limestone
mountains and germination commences, their further development is visibly
retarded; they dwindle wherever there is not much lime, and are overgrown
and suppressed by the siliceous species which flourish there so luxuriantly. The
brown or black mass formed by the decomposition of dead plant residues, known as
humus, plays a very important part in the contrasting vegetation on limestone and
slate mountains. To obtain a true idea of its significance it must first be pointed
out that three distinct stages can be distinguished in the development of a
continuous and intricate plant-covering. To the first stage belong the plants
which settle down on the bare earth content with a substratum wholly devoid of
humus; in the course of time they conquer the-most barren rock, the barest
boulders, and the dreariest shifting sands. The species of this group belong chiefly
to the Lichens, Mosses, Grasses, Pinks, Crucifers, House-leeks, Saxifrages, and
Composites, whose spores, seeds, and fruits are exceptionally well adapted for wind
distribution, and can be transferred with ease to the steepest slopes and the most
uncompromising crags. The second stage includes plants which require a moderate
amount of soil mixed with humus; they establish themselves on the ground pre-
pared by the first settlers, wresting it from them and taking possession, and then
suppressing and overgrowing them entirely. These plants belong to very different
families, whose distribution and establishment are effected in very many ways to
be described subsequently. The third stage of development consists of plants for
which the abundant humus stored up successively by the plants of the second stage
is absolutely indispensable. Bog-moss, Lycopodiums, Sedges, and Heaths form the
chief part of this stage. In the course of years the amount of inorganic materials
in the soil which supports the plants of the third stage continuously diminishes.
Plants which require a large quantity of inorganic salts languish, and are, moreover,

INFLUENCE OF THE SUBSTRATUM. 499

overcome by saprophytes which find a suitable habitat there and flourish in
abundance, The decayed portions of Saprophytes contain relatively little inorganic
material. No trace of lime (in particular) is to be found in their ash. In this way
a superficial layer of humus is formed which actually excludes a large number of
plants. The next deeper layer may contain a considerable quantity of inorganic
salts, but they are valueless to plants rooted in the upper (humus) layer, as they
cannot penetrate it. It has been shown by experiment that pure humus possesses
the power of holding back materials which are soluble in water. It possesses this
property to such an extent that if salt solutions are filtered through a layer of
humus the water which escapes below is almost pure. It is therefore impossible
for inorganic substances from the deeper layers of the soil, much less from the
underlying rock, to reach the surface layer of humus in solution by diffusion; and
if some mineral ingredients are not introduced by irrigation or flooding, the upper
layer of soil consists of pure humus on which only saprophytic plants can flourish.

The formation of such layers of humus occurs much more easily and quickly on
slate mountains than on limestone, because in the former the rock and the products
of its decomposition retain water much better, and a uniform saturation promotes
the development of humus, and also because on slaty soil the second stage of the
development of the plant-covering consists of plants which require very few inor-
ganic food-substances, and accordingly very few inorganic materials are yielded
by the humus, which originates at the cost of the decaying portions of these plants.
But a thick stratum of pure humus may also arise in course of time on lime-
stone mountains. Only the soil must be uniformly moist in that spot, and
neither sand nor mud must be deposited on it. If these conditions are fulfilled a
deep humus will gradually spread itself over limestone rocks and débris in the
third stage of development, the superficial layer of which will contain no trace
of lime, but will afford an excellent soil for silica-loving plants (2.e. for those to
which lime is injurious). The isolated occurrence of so-called siliceous or slate-
plants on limestone mountains, even in the middle of a patch of plants which are
characteristic of a limestone soil, may be naturally explained in this fashion.

The water which moistens the rock and soaks the soil has, apart from its
mechanical action, the important function of opening up mineral substances and
of forming solutions from which the absorbent plant-cells may take their choice.
The atmospheric water which penetrates into the earth from above is especially
valuable as a solvent on account of the carbonic acid gas it contains. It is
immeasurably more valuable to every part of the soil which is riddled by the
roots of living plants than the soil-water, so poor in carbonic acid, which collects on
impervious strata of the soil and soaks upwards through the superficial layers.

The power of the soil to retain water depends mainly on the extent of breaking
up undergone by the rock whose disintegration has formed the soil and upon the
amount of clay which has arisen from this disintegration. But the amount of
humus which in course of time has mixed with the disintegration and the decom-
position products of the underlying rock is also an important factor, and thus very

500 DEPENDENCE OF PLANT FORM ON SOIL AND CLIMATE,

complex conditions arise which render the estimation of the soil’s capacity for
retaining water very difficult. If permeable sandy soil, poor in humus, is deprived
of ground water and is dependent for its moisture solely on the atmosphere, the
plants growing in it will be retarded in their development if rain and dew are
absent for any length of time, and their outward appearance will be altered by this
restriction of growth. Annual plants subjected to a lack of moisture in the soil
just at the time when their growth should be at its maximum, show best how far
these alterations will go. The stem-structures remain short, the foliage-leaves
shrink to their smallest extent, and no lateral shoots are developed. Only a few,
or perhaps only one, of the flower-buds mature; it is small, opens comparatively
very early, and the whole plant has a dwarfed aspect. Annual plants of the Poppy
(Papaver Rheas, somniferwm), Pheasant’s Eye (Adonis estwwalis, flammea), Corn-
cockle(Agrostemma Githago), Cornflower (Centawrea Cyanus),and common Groundsel
(Senecio vulgaris) grown on a dry soil differ from plants grown in the same place,
but in a damp year, to such an extent in the size of all their parts that at first sight.
they might be mistaken for other species. A clay soil which retains water is less.
exposed to danger of too great dryness, but if it is not mixed with humus, and
therefore loosened, it has the disadvantage that the water it contains cannot take-
up the inorganic foods quickly enough and in sufficient quantity for the require-
ments of the plants. This drawback explains the surprising fact that plants grown.
on heavy wet clay soils have a dwarfed appearance exactly like plants growing on
dry sandy soil. In regions liable to flooding by streams and rivers where not.
infrequently sandy and clay soils, in all degrees of porosity and admixed with
humus in all possible proportions, are to be met with within a few yards of one
another, certain species of plants are to be found growing near together in all imagin-
able degrees of size, e.g. Aster Tripolium, Bidens cernua and tripartita, Polygonum
lapathifolium, Rumea maritimus, Veronica Anagallis. In places where the
seedlings cannot find enough free mineral foods, in spite of the abundant moisture
in the soil, the stem rises to some 3-8 cm.; in places which favour the absorption of
food, to some 50-80 cm. We will describe only one species, Veronica Anagallis,
more in detail. Plants of this species are found with stems 3-5 cm. high and 0°5
mm. thick, with foliage-leaves 6-12 mm. long and 5-6 mm. broad when fully
developed. The number of flowers in one inflorescence is about 4-5, the calyx and
ripe capsular fruit measure 3 mm. in length. Contrasting with these are plants
with stem 30-50 cm. high and 7-8 mm. thick, whose fully-formed leaves are 80 mm.
long and 85 mm. broad. There are 40-50 flowers in each inflorescence, and the
calyx and ripe capsule measure 4-5 mm. in length. Generally speaking these
plants are about ten times as large as the others. If the soils which give rise to:
such surprising differences in size are examined it will be noticed that the dwarfed
specimens are rooted in a heavy soil devoid of humus, while the large luxuriant.
plants flourish in a clay soil which is mixed with plenty of humus, and is
therefore very open. Obviously the plants could not obtain from the heavy clay
soil what they required for the structure of a vigorous plant, even although the

INFLUENCE OF THE MEDIUM. 501

ground was well moistened and warmed; but this they could obtain in abundance
from the saturated clay soil containing the humus.

It has been already stated that the ground water is less favourable for vegetation
than rain and dew on account of its paucity of carbonic acid. But the moistening
of the ground by water which wells up from below brings other evils in its train.
By this means the soil is over-saturated for a long time, a condition which the roots
of most land-plants will not tolerate. When it remains stationary for a long while
potassium and sodium salts, and, under certain conditions, humous acids pass into it
from the wet earth in quantities anything but advantageous to the plants. Vege-
tation, therefore, exhibits a scanty growth in places where the ground water
influences the stratum of soil penetrated by roots, and it usually consists of
comparatively few species.

In low-lying regions, where the ground water rises to the surface, we have the
formation of lakes and ponds with variable water-level. Sometimes the plants
growing in such places are quite submerged, while at other times their stem
and leaves are above water. Land plants do not take kindly to this. Most of them
cannot survive very long immersion; they become suffocated, die, and decompose
under water in a few days. Only a few species have the remarkable power of
growing equally well below or above water, and these are, of course, extremely
interesting on account of their form. In accordance with the great contrast
presented by the external conditions of life to which these species are temporarily
exposed we have a fundamental change both in their outward appearance and in
the internal structure of their several organs. In order that the stem and leaves
should be held in the best position by the flowing water, the mechanical tissue in
submerged varieties of these species is much reduced (see vol. i. pp. 424 and 665).
They are also devoid of the contrivances which usually regulate transpiration, since
no evaporation occurs under water. Stems grown under water consequently appear
limp and flaccid when taken out of it; their leaves, when compared with those
growing in the air, are much weaker and more delicate. They have no gloss, but
are brighter green in colour, and in the air they collapse and dry up in a very
short time. A vertical section through the leaf shows that the number of cells
between the upper and lower epidermis is much reduced, and that the cells are
shortened in a direction perpendicular to the leaf surface. The foliage-leaves of
Veronica Beccabunga, when grown under water, are hardly one-third as thick as
those grown in the air, and between the upper and lower epidermis there are only
4-5 layers of short cells, while in corresponding leaves of aérial plants there are
10-12 cell-layers and a distinct division into palisade and spongy parenchyma (see
vol, i. p. 279). The shape of the leaf is also much changed under water. In
Veronica Beccabunga the difference in aérial and submerged leaves is very slight,
consisting only in the shortening of the petiole and in the marginal teeth becoming
less marked. In Veronica Anagallis, likewise, the alteration in shape is incon-
siderable, but in many others it is very noticeable, and we shall return to it when
speaking of the influence of light.

502 DEPENDENCE OF PLANT FORM ON SOIL AND CLIMATE.

Plants rooted in the mud of a river-bed, the stems and leaves of which are
surrounded by rapidly-flowing water, must possess corresponding strength if
they are not to be torn. In comparing two plants of the same species, the one
growing in the still water of a deep lake, the other in a rapidly-flowing stream,
it will be noticed that the walls of the superficial cells of the latter have become
strongly thickened, and that strong bundles of bast-fibres have developed in the
cortex of the stem, while in the former only the weakest traces of bast-fibres
can be seen. The extraordinary length of stem, petiole, and leaf-blade is also
very surprising in plants which grow in rapid water. The Pondweed Potamogeton
fluitans, the Rushes Juncus lamprocarpus and swpinus, the Grasses Agrostis
stolonifera and Glyceria flwitans are very instructive examples. A plant of
the last-named Grass growing on damp soil on the edge of a stream over the
water had linear, bluntly-pointed leaves, whose sheaths were on the average 15 cm.
long, the blades 23 em. long and 85 mm. broad. After this plant had been sub-
merged under rapidly-flowing water in the following year, leaves unfolded, which
tapered gradually to a point, with a sheath having a mean length of 47 em., and
blades 73 em. long but only 5 mm. broad. The blades produced in running
water were three times as long and actually rather narrower than in the air.
There was no difference in the number of strands traversing the blade, but they
were nearer to one another than in the aérial leaves. The Arrow-head (Sagittaria
sagittifolia), which usually grows on the muddy bottom of shallow lakes, raising
its leaves above the still water, has gained its name from the likeness of its
leaf-blade to an arrow. If it is planted in the bed of a rapid stream so that
the leaves during their development are exposed to a vigorous current, the
leaf-blade is almost entirely suppressed. What still remains has the form of a
spade, but not infrequently all trace of lamina is wanting. The petiole, however,
lengthens to 70 cm., and forms a limp, flat, pale-green ribbon 1-2 em. broad,
which might easily be mistaken at first sight for the leaf of Vallisneria.

Another remarkable change which is effected by submerging growing plants
is the non-development of the epidermal structures called hairs, so that the leaves
and stems of submerged plants always appear smooth. The suppression of hair-
structures is very noticeable in the aquatic variety of Polygonum amphibium.
In aérial plants of this species the leaves have short petioles, are lanceolate in
shape, and are covered thickly with short hairs, which are rough to the touch;
while the aquatic plants have long-stalked, broadly-linear leaves completely smooth
on both sides.

The humidity of the atmosphere has a marked effect on the form of land
plants. Transpiration, which is so deeply concerned in all the vital processes,
is carried on very slowly in air which is almost or quite saturated with water-
vapour. If plants of a species which usually grows in dry air come into a humid
atmosphere, they must be furnished with means for aiding evaporation, On
the other hand, plants which grow in dry air must be protected against excessive
transpiration. The aids and protective measures were so minutely described

INFLUENCE OF TEMPERATURE. 503

in vol i. pp. 284 and 307, that it is needless to repeat them here; but it should
be noted that the capacity of plants to construct their tissue as need requires,
either for aiding transpiration or for protection against excessive evaporation,
is very limited. It must also be pointed out that it is very difficult to distinguish
clearly between the direct effect of the humidity of the air and the effects of
other influences. Heat and light, as well as the amount of moisture in the soil,
are intimately connected with the humidity of the air, but the relations are
difficult to estimate. To a certain extent they are interchangeable, and therefore,
in most instances, it is impossible to say which extermal influence is the cause of
any particular alteration in the tissue concerned in transpiration. For the answer
to the chief question, whether it is possible for a change in the conditions of
life to cause an alteration of form in the sense of an adaptation, it is really a
matter of indifference which influence causes the visible effect. Only here, as in
so many other cases, matters are simplified if a certain partiality is permitted in
experiments for solving these difficult questions, and if the interwoven influences
of soil and climate are treated separately.

The effect of heat on growing plants was discussed at vol. i. p. 523. It only
remains to say here that the formation of starch and other reserve-foods, as
well as the formation of sugar in fruits, is largely connected with heat. Fruits
of the same species which ripen under a higher temperature differ greatly in the
amount of sugar they contain from those ripening at a lower temperature. It is
generally accepted that the size also of the stem, foliage, flowers, and fruit is
influenced by heat. The changes which occur when plants in flower, after being
for some time in a very warm room are transferred into a cooler room, the
other conditions remaining the same, are in particular now recognized. When a
large-flowered bulbous plant, eg. the Belladonna Lily (Amaryllis Belladonna),
is transferred to a cold greenhouse after opening its first flowers in a warm one,
the flowers it here develops at a lower temperature are almost a third smaller
than those produced in the warm house. But when the first flowers open in
the cold, and the later ones in a warm atmosphere, the former remain small
and the latter are larger in size. It is important to emphasize this circumstance
in order that the phenomenon here exhibited may not be mistaken for another,
in case we should be led to think that the flowers of a plant which first unfold
are larger than those which succeed them even when there has not been the
slightest alteration in the conditions of light, heat, humidity, &c.

It is particularly instructive, when examining the effect of heat on the form
of a species, to compare plants grown in water of different temperatures but
under conditions otherwise similar. In mountainous districts the springs on the
same mountain slope have a different temperature according to their elevation,
and yet the same species of plants may be found growing in springs at the foot
and high up on the mountain. Let us take as examples plants of Cardamine
amara, Myosotis palustris, Pedicularis palustris, and Veronica Beccabunga.
These species grow at the foot of the Patscherkofel, near Innsbruck, in the bed

504 DEPENDENCE OF PLANT FORM ON SOIL AND CLIMATE.

of streams with a mean temperature of 102 °C., but they also flourish in a stream
above the tree-line, at a height of 1921 metres above the sea-level, known as the
“Kreuzbrunnen”. Comparing plants of the same species growing under the
influence of these different temperatures, the following differences are to be noted :—
Plants of Veronica Beccabunga growing in spring water at a temperature of
102° C. were 20-50 em. high, and displayed 4-6 internodes between the bottom
in which they were rooted and the level of the first inflorescences. The internodes
of the stem were 60-120 mm. long and 5 mm. thick; the leaves springing from
the middle of the plant were 40-60 mm. long, 20-25 mm. broad, and each of the
flower racemes had 12-16 flowers. Plants growing in the spring water at a
temperature of 42° C. were 10-15 em. high with 4-6 internodes between the
ground and the level of the first inflorescences. The internodes were 15-30 mm.
long and 10-12 mm. thick, and each inflorescence had 12-16 flowers. Cardamine
amara, Myosotis palustris, and Pedicularis palustris behaved similarly. There
seemed to be no alteration in the form of the leaves and flowers; the corollas
assumed a rather deeper tint in the Kreuzbrunnen; Myosotis palustris, which
was 20 cm. high at the foot of the Patscherkofel, was 4-5 cm. high in the Kreuz-
brunnen, and closely resembled the Eritrichiwm nanum of the Southern Alps
in the deep blue of its corollas. Cardamine amara, in the same cold spring, in
addition to the shortening of its internodes and diminution of its foliage-leaves,
displayed a red colour on the outside of its white petals which was not present
in plants at lower levels.

The powerful influence of light on the development of plants was discussed at
vol. i. p. 371. The question now before us is how far bright and subdued light are
able to alter the size, form, and colour of plants. The following is a general review
of what has been ascertained in the matter from experiments and direct observa-
tion of nature. When plants of a species develop in subdued light they always
have higher stems and longer leaves than when grown in bright light, provided,
of course, that the conditions of moisture and temperature have been as far as
possible identical. This difference is especially noticeable in comparing two plants
of a species, one of which has developed in the dim light of a greenhouse in the
short days of winter, the other in an unshaded place in the open country during
the summer when the light lasts for 16-17 hours every day. The former has a
lank thin stem, delicate yellowish-green leaves, and either none of its flowers
unfold or else they have a weak appearance and their corollas are pale and flaccid.
The illuminated plant has, on the other hand, a compact vigorous stem, dark green
leaves, and unfolds a multitude of bright-hued flowers. One only of the large
number of experiments which have been performed for the purpose of determining
this matter definitely will be mentioned here—one indeed which shows how far
the form of the flowers also may be affected. Seeds of a biennial Saxifrage,
Samifraga controversa, which were sown in several flower-pots filled with similar
soil, produced numerous young plants. A pot with six of these young plants
was taken in the autumn into the hot-house; another, likewise containing

INFLUENCE OF LIGHT. 505

six young plants, passed the winter under a thick coat of snow in the open.
At the beginning of December the six plants in the hot-house sent up from
the centre of their small leaf-rosettes slender stalks 10 em. high, whose upper
internodes were 22 mm. long and 1 mm. thick. The stem-leaves were yellowish,
entire, elongated, 6-7 mm. long and 2 mm. broad; calyx-tube 4 mm. long, 13 mm.
broad; calyx-teeth 2 mm. long, 15 mm. broad; petals 35 mm. long, 2 mm.
broad; stamens 1 mm. long. It was noted that lateral axes only developed in
the axils of the upper stem-leaves, and that the buds of the lateral shoots in the
lower leaf-axils atrophied. In the following May strong stems 6 cm. high were
sent up from the leaf-rosettes of the plants which had wintered under the deep
snow in the open; their upper internodes were 12 mm. long and 2 mm. thick.
The stem-leaves were somewhat broadened in front with dentate margin, red in
colour, 5 mm. long and 3 mm. broad. The measurements of the parts of the
flowers were:—Calyx-tube, 2 mm. long, and 2 mm. broad; calyx-teeth, 15 mm.
long, 1 mm. broad; petals, 2°3 mm. long, and 2 mm. broad; stamens, 1 mm. long.
From the axils of the stem-leaves flower-bearing shoots developed, which, like the
parts of the main stem exposed to the sun, were coloured red. Here then the
alterations which certainly are due to the various light influences consist not only
in the lengthening and shortening of the stem- and foliage-leaves, but the flowers
are correspondingly changed. The petals of the flowers which opened at the New
Year when the days were shortest were not only relatively but actually narrower
than those which belonged to flowers which opened in the early summer when the
days were longest.

It has already been stated that the elongation of the leaves and the division of
the leaf-lamina into long narrow segments in submerged leaves is associated with
the diminution undergone by the light in passing through the water (see vol. i.
p. 665). The elongation of submerged leaves is very well seen in the water Star-
wort (Callitriche) and Mare’s-tail (Hippuris). In the latter the linear submerged
leaves are thirty times as long as they are broad, while the length of the aérial
leaves is only 7-9 times their width. In Rorya amphibia the leaves which
develop under water are deeply cleft compared with those produced in the air.
The aérial leaves of this Crucifer are linear-lanceolate, about ten times as long as
broad, with finely toothed margin. Under water the leaves have an elliptical
shape, are 2-3 times as long as broad, and the lamina is cleft almost down to the
midrib in narrow segments 2-3 cm. long, like a comb or feather. The aérial
leaves of the whorled Waterwort (Llatine Alsinastrwm) are grouped in whorls of
three. They have an ovate shape, and their margins are finely notched. Lach is
traversed by 3-5 veins. The leaves developed under water are divided almost
their whole length into 3-4 narrow linear segments, and each whorl looks as if it
were composed of twelve leaves. Each segment is smooth round the edge, and
traversed only by one central vein. The difference between the aérial and sub-
merged leaves of the white-flowered Crowfoots (belonging to the Batrachiwm
section of the genus Ranunculus) is even more surprising. Plants of these Crow-

506 DEPENDENCE OF PLANT FORM ON SOIL AND CLIMATE.

foots which have developed on muddy but not inundated ground display three-
or five-cleft leaves whose segments are light green in colour, shiny, and almost
fleshy, and spread out flat. When these plants are grown under water the leaves
appear quite different; they become divided into numerous thread-like or hair-
shaped segments which have a dark-green colour, and the polished surface has
entirely disappeared.

The shade afforded by stones, loose earth, undergrowth, and neighbouring
bushes and shrubs acts on growing stems, foliage-leaves, and flowers just in the
same way as the light-subduing layer of water. In a place near my country house
which was formerly used for storing wood and dry twigs, but which had remained
unused for a long time, the Creeping Thistle (Cirsiwm arvense) had established itself
and formed an intricate growth. The crowded stems attained a height of 80 cm.
at the time of flowering and fruit ripening. In the winter of 1885 wood was
again stored there in piles 150 cm. high. When, early in the following summer,
the new shoots of the Thistle began to spring up they were obliged to content
themselves with growing through the dark chinks between the blocks of wood.
Many were thus forced to bend and twist, and finally came against some insur-
mountable obstacle so that they dwindled in the crevices of the wood-stack without
ever reaching the light. Others again which were able to find a fairly straight
road through the crevices grew up until they reached the surface of the wood-heap,
they then continued to grow 50 cm. higher and unfolded large foliage-leaves on
this upper portion. They also developed branches with flower-heads, and from
a distance it looked as if a group of Thistles had grown on the top of the wood-
stack. The stems had attained a height of 2 metres. The lower internodes were
twice as long as usual, the foliage-leaves which sprang from the stalk inside the
dark crevices were small, yellowish green, and the buds in their axils did not
develop. The Cow-berry (Vaccinium Vitis-Idewa) behaves similarly when its
shoots are obliged to grow up to the light through dead tree-trunks. Shoots which
force their way in the dark between the bark and the wood of the trunk may
reach the height of a metre, while neighbouring ones, springing directly from the
soil of the forest are only 15 cm. high. The shoots inside the bark have a reddish
colour, and they bear small pale scales instead of dark-green foliage-leaves.

From the creeping stems of the White Clover (Lrifoliwm repens) spring erect
petioles terminating in three leaflets, and an erect angular stem bearing a flower-
head. In sunny places, especially where no neighbouring plants cast a shade, the
petioles reach a length of 8 em, and the stem of 10 em. But if dense bushes
overshade the Clover, the petiole and stem elongate until the leaflets and capitulum
they bear reach the light. Under these conditions petioles 28 cm. long have been
found, and stems attaining a height. of 55 em. An extraordinary elongation also
occurs in the radical leaves of the Dandelion (Taraxacum officinale) in places
where high Grasses and thick bushes shade the moist soil. In the open the leaves
reach a length of 20 cm., but in the shade they become twice or three times as
long. The lower part of the leaf lengthens most, the free end is comparatively

INFLUENCE OF LIGHT. 507

very little altered, and in the central portion the only change is that the lobes and
teeth become shorter and less clearly marked.

In order to ascertain the effect of covering plants with earth, numerous bulbs
of a species of Tulip (Tulipa Gesneriana) were planted at the same depth in one
garden bed, and in another some corms of the Spring Crocus (Crocus vernus).
Earth was heaped over these bulbs und corms in successive heights of 5, 10, 15, 20,
25, 30, 35, 40, 45, and 50 cm. Naturally the leaf-tips and flower-buds were first.
seen in the places where the bulbs were only covered with 5 cm. of soil; in both
beds the development was delayed—in the other cases in proportion to the height.
of the soil above the bulbs. Some flower-buds of the Crocus appeared above the
20 em. of soil, one of the Tulip above the 30 cm. Numerous leaf-tips of the
Crocus appeared above the 35 cm., and a few of the Tulip above the 40 em. of soil.
The perianth-tube, the peduncle and the foliage-leaves were almost twice as long as
those which had developed under only 5 em. of soil. The flowers were smaller, and
unfolded just above the soil; the leaves were narrower and pale yellow in colour
as far up as they were covered with the soil. Neither the Crocus nor the Tulip
raised their leaves higher than 40 cm. Apparently the reserve-materials stored in
the corm and bulb-scales were not sufficient for a further elongation. The stems
and leaves of the Crocus and Tulip thus exhibit alterations similar to those
observed in the sprouts of Potato-tubers in a dark cellar.

We should expect that if moisture and lack of light produce elongation of
shoots and various alterations in leaves, a brilliant illumination would have the
opposite effect on growing plants. This is indeed the fact. Plants which have been
for a year in the shade and have been placed at the beginning of their development.
in the following year in the sun display shorter internodes and firmer leaves; they
blossom more abundantly, the flowers are of a deeper hue, and in many cases a
covering of hairs is formed over the green portions. It is not necessary to mention
how far transpiration, which is much more active in the sun than in the shade, is
concerned in this; these alterations are certainly produced in the end by sunlight.

The effect of brilliant illumination is best seen by comparing plants grown from
similar seeds at different elevations, but under identical conditions in other respects.
The results obtained in my experimental garden near the summit of the Blaser in
the Tyrol, at a height of 2195 m., during the years 1875-1880 illustrate this very
fully, and I will briefly recount them here. The seeds of some annual plants were
sown in September. The beds were covered with a layer of snow a metre thick
throughout the winter. The germination of the seeds took place in the following
year soon after the snow melted between the 10th and 25th June. The seedlings
therefore developed during the time when the sun was highest and the days longest,
and the young plants were exposed to a temperature not lower but rather higher
than that enjoyed by plants from similar seeds which began to develop in the
experimental beds of the Vienna Botanic Garden in March, when the daylight
lasted about 12 hours. The seedlings of several species (e.g. Gilea tricolor, Hyos-
cyamus albus, Plantago Psyllium, Silene Gallica, Trifolium incarnatum) were

508 DEPENDENCE OF PLANT FORM ON SOIL AND CLIMATE.

killed by the isolated frosts which occurred in each of the six years of the experi-
ment, not only in the last week of June, but during July and August; but others —
(eg. Agrostemma Githago, Centaurea Cyanus, Ibveris amara, Lepidium satiwum, |
Satureja hortensis, Senecio vulgaris, Turgenia latifolia, Veronica polita, Viola
arvensis) only underwent a short temporary stoppage of growth from this cause,
and opened their flowers at the end of August and beginning of September. In
the plants of some species (e.g. Senecio vulgaris, Veronica polita, Viola arvensis)
ripe seeds capable of germinating were formed in September. The flowering speci-
mens, in comparison with those which had grown during the short days of the
spring exposed to numerous night-frosts in the Vienna gardens, displayed extremely
shortened internodes. The number of internodes was also lessened, or rather,
fewer were developed. For example, where 10 internodes developed in an experi-
mental plant in Vienna, in the Alpine garden a corresponding plant would only
have 5-6. The same was true of the development of the flowers. While in a plant
of Viola arvensis in Vienna the axillary buds of the first six foliage-leaves were
suppressed and flowers were not produced until the seventh and eighth leaves,
flowers grew from the third and fourth axillary buds in the same species of plant
grown in the Alpine experimental garden. The number of flowers on a plant was
less, the petals were smaller on the average, and, generally speaking, the annual
plants in the Alpine garden had the same appearance as those grown in the plain
on dry, sandy soil described on p. 500. It has already been stated on p. 453 that
some of the species which are annuals in the valley and on the plain do not die
in the autumn in the Alpine garden, but remain alive through the winter and in
the following year develop new shoots from the stem.

To describe the alterations undergone by biennial species in Alpine regions we
will take Libanotis montana (an Umbeilifer) as an example. Its stem in the
Alpine garden was 16-24 em. high and developed 5 internodes which were 2-5 cm.
long. From the axils of the 5 green stem-leaves sprang lateral shoots which did
not branch but terminated in a single umbel, so that the plant only bore 5 umbels
altogether. The plants grown from similar seeds in the Vienna Botanic Garden
exhibited a stem more than a metre high with 10 internodes each 10-20 em. long.
No lateral shoots were produced from the axils of the lower stem-leaves. Those
from the axils of the middle and upper leaves were branched and bore several
umbels, On an average a plant had about 20 umbels altogether.

Over 300 species of perennial plants were grown in the Alpine experimental
garden. Only 32 of them blossomed, however. Those whose flowers usually pre-
cede the foliage-leaves were in full blossom at the beginning of July, the others,
which had to develop a leafy stem before their flowers appeared at the top or
in the axils of the leaves of this stem, did not flower until the end of August and
beginning of September. Three species of the latter kind will be more particularly
treated of here; one species whose stem bears only a single leaf and is terminated
by a single flower (Parnassia palustris), one whose stem is beset with decussate
leaves and terminates in a loose inflorescence composed of small cymes (Lychnis

INFLUENCE OF ELEVATION. 509:

Viscaria), and a third whose stem bears alternate leaves and whose flowers are
grouped in capitula (Pyrethrum corymboswm).

The Grass of Parnassus (Parnassia palustris) from the Alpine garden, when
compared with plants grown in the experimental beds of the Vienna Botanic
Garden, showed the following measurements:—

Vienna Botanic Garden, Experimental Garden on the Blaser.

Height of stem ...........00606 20-27 cm. 5-9 cm.
Dimensions of leaf............... 3°3 cm. long, 2°4 cm. broad. 10 cm. long, 0°6 cm. broad.
Diameter of flower ...........0.. 2°8-3°4 cm, 1:8-2°0 cm.

In the Alpine regions, therefore, the plant was only 4 or }{ as high and the leaves
only }-} as large as in Vienna, whilst the flowers in the Alpine region had a much
smaller diameter than in Vienna.

Comparing the hermaphrodite plants of Lychnis Viscaria in the experimental
garden of the Blaser with those of the same species at Vienna, we obtain the
following :—

Vienna Botanic Garden. Experimental Garden on the Blaser. |.

Height of the stem, includin :

ihe axis of the indbrescenice: ; Se OW ait: 250-20 Dae,
Dimensions of lower leaves...... 80 mm. long, 4 mm. broad. | 50 mm. long, 3 mm. broad.
Inflorescence............ceeeeeeeeeeeee 80 , , 50 ,, 55 60 ,, » 40 5 53
Reh ecati eoccncarencmls 15 4 oy BB ys 135 Ge ye Be
Lamina of petals ............0cceees 10> ss Be | 45 53 fae 68 ,, a
Claw of petals.........:cccceecereeees 8 mm. long. 7 mm. long.

Plants from the Alpine garden, therefore, when compared with those from the
Vienna Botanic Garden, exhibit smaller measurements of stem, leaves, and flowers.
The following points were also noted: the number of internodes in plants from
the Vienna Garden was 9, of which 5 were on the axis of the inflorescence; each
cyme consisted of 3-5 flowers, and the whole inflorescence bore 33-40 flowers.
Plants from the Alpine Garden had only 6-7 internodes, of which 3 belonged to
the inflorescence; the cymes composing the inflorescence were only occasionally
3-flowered; in most of them only the central flower developed, the two lateral ones
being suppressed. The whole inflorescence included only 5-11 flowers.

Plants of Pyrethrum corymbosum, from the Alpine Garden, compared with
those from the Vienna Botanic Garden (all raised from one batch of seeds) showed
the following differences:—

Vienna Botanic Garden.

Experimental Garden on the Blaser.

Height of the stem,...............
Dimensions of leaves,............
Diameter of the capitulum,....
Ray-florets,.......:ccsceeseeeeeeenes

950 mm.

170 mm. long, 50 mm. broad.

26 mm.
8 mm. long, 4 mm. broad.

250 mm.
45-50 mm. long, 20 mm. broad.
20 mm.
7 mm. long, 3 mm. broad.

510 DEPENDENCE OF PLANT FORM ON SOIL AND CLIMATE.

In this case, again, plants from the Alpine Garden, when compared with those
of the Vienna Botanic Garden, had smaller stems, leaves, and flowers. The lobes
of the foliage-leaves from the middle of the stem of plants from the Alpine Garden
were pinnate, and the pinne were either entire or beset with two small teeth
on each side, near the apex. The stem had ten foliage-leaves, the four uppermost
of which were much reduced and served as scale-leaves for the lateral shoots
arising from their axils. These lateral axes were not branched, and each bore
only a single capitulum. There were five capitula altogether. On plants from
the Vienna Botanic Garden the lobes of the foliage-leaves from the middle of
the stem were more divided, and the pinne were beset on each side near the
top with 3-5 teeth. The stem bore 25-27 foliage-leaves, of which the 6-8 upper
ones were much reduced in size, and functioned as scale-leaves for the lateral
shoots in their axils) These lateral shoots were branched, and each branch
terminated in a capitular inflorescence. The total number of capitula was 20-80.

From these examples it will be seen that all the parts of plants grown in
the Alpine experimental garden were much hindered in their growth. The
foliage- and floral-leaves were smaller, the stems shorter, the number of internodes,
foliage-leaves, inflorescences, and flowers was diminished. The flowers were
relatively nearer the earth, and this was due not only to the diminished number
and length of the internodes of the stem, but principally to the fact that the
flowers sprang from the axils of the lower stem-leaves.

Plants growing in Alpine regions derive a great advantage from these altera-
tions, which are chiefly produced during their development by the influence of
the long and bright daylight of June, July, and August. If these plants had
to produce the same under-structure as their fellows in the Vienna Botanic
Garden, 2015 metres lower down, much time would be lost, and the earliest
flowers would hardly open before October, at a time when the winter snow is
already beginning to fall. But since the number of internodes is restricted, and
flowers are developed from the lower stories, it is possible for the plants to blossom
at the end of August and beginning of September, and perhaps to ripen their
fruits—one of the chief aims of the plant’s existence. To this modification in
their mode of development is also due in part the repeatedly-mentioned fact
that many alpine plants blossom earlier than those in lower regions. But in
order to avoid misunderstanding, it must be expressly stated that in not one of
the thirty-two perennial, nor in the biennial and annual species which blossomed
in the Alpine experimental garden, was the early flowering hereditary; con-
sequently these plants must be carefully distinguished from the so-called asyn-
gamic species, which will be spoken of in one of the last chapters in this book.

The relation of light to the colouring matters of plants has been repeatedly
the subject of careful investigation. All observers agree that the amount of the
pigment known as anthocyanin increases and diminishes with the stronger or
weaker sunlight enjoyed by the parts of the plant in question, and that the
yellow colouring matter of flowers holds a similar relation. Chlorophyll, however,

COLOUR AT DIFFERENT ELEVATIONS. 511

is actually destroyed by bright light in plants which are not properly screened,
and the green tissue is then blanched and assumes a yellow tint. Since the
intensity of the sun’s rays increases with the elevation in mountain districts
(see vol. i. p. 525), we should expect that this effect of light would be shown
particularly well in plants of high elevation. And this is certainly the case.
The flowers of species grown in the Alpine garden on the Blaser at a height
of 2195 metres above the sea exhibited, as a rule, brilliant floral tints, and some
were decidedly darker than the flowers grown in the Vienna Botanic Garden.
Agrostemma Githago, Campanula pusilla, Dianthus inodorus (sylvestris), Gypso-
phila repens, Lotus corniculatus, Saponaria ocymoides, Satureja hortensis,
Taraxacum officinale, Vicia Cracca, and Vicia sepiwm are good examples of this.
Several species, which produced pure white petals in the Vienna gardens, eg.
Inbanotis montana, had petals coloured reddish-violet by anthocyanin on their
under sides in the Alpine garden. The glumes of all the Grasses which were
green, or only just tinged with violet at a low level became 2 dark brownish-
violet in the Alpine garden. The abundant formation of anthocyanin in the
green tissue of the foliage-leaves and sepals, and in the stem, was particularly
apparent. The leaves of the Stonecrops, Sedum acre, album, and sexangulare
became purple-red, those of Dracocephalum Ruyschianum and Leucanthemum
vulgare violet, those of Lychnis Viscaria and Satureja hortensis a brownish-
red, and the foliage-leaves of Bergenia crassifolia and Potentilla Tvroliensis,
even in August, had the scarlet-red colour which they usually assume in sunny
spots in the valley in late autumn. I must not omit to mention that, according
to some of my zoological friends, many animals, especially spiders and snails, which
have been transferred from the plains to the mountain-heights, assume a darker
tint in alpine regions.

A considerable number of plant species, especially those which grow in the
valley in shaded or half-shaded places, as, for example, Arabis procurrens, Digitalis
ochroleuca, Geum urbanum, Orobus vernus, Valeriana Phu, and V. simplicifolia,
Viola cucullata, developed more or less yellowish leaves in the Alpine garden,
where they were exposed to the full sunlight. It was mentioned in vol. i. p. 393,
that the Flax (Linum usitatissimum), which flourishes in mountain valleys
at a height of 1500 metres, where its chlorophyl! is uninjured, nevertheless
turns yellow in the Alpine garden at a height of 2195 metres.

From this general review of the modifications in plant-form obtained by
culture-experiments, a series of important conclusions may naturally be drawn.
In the first place we must point out that two kinds of characters are to be observed
in plants, those which are the result of certain conditions and properties of soil
and climate, and those which appear independently of these external influences.
This distinction is so important that we shall illustrate it by two examples.
The white Water-lily, Nymphwa alba, develops scale-leaves of ovate or lanceolate
shape with no separation into petiole and lamina. The foliage-leaves, however,

512 DEPENDENCE OF PLANT FORM ON SOIL AND CLIMATE.

have a rounded petiole and a disc-shaped lamina. These characters are always
present whether the seed which produced the plant germinates in a deep lake
or in the mud of a marshy meadow. In the marshy meadow the scale-leaves
remain short, and the walls of their epidermal cells thicken in a remarkable
way; the petioles of the aérial foliage-leaves become about a span long, and, in
order to increase their resistance to bending, a strong layer of bast arises, the
thickness of these bast-layers amounting to 0°17 mm. The walls of the epidermal
cells are thickened, 5-9 layers of collenchymatous cells are formed under the
epidermis with walls 007 mm. thick, and the air-spaces in the centre of the leaf-
stalk are much narrowed. But if this species of Water-lily grows under water,
the scale-leaves elongate into long and flaccid ribbons, and the petioles of the
foliage-leaves continue to grow until their blades are raised to the surface of the
water. According to its depth they attain a length of 30, 40, 50-100 ecm.
Resistance to bending is but little required by the petioles, which are surrounded
by water, and the bast is therefore only slightly developed. The strings of
bast which traverse the leaf-stalk are only 0°11 mm. thick, the walls of the
epidermal cells are only half as thick as in the aérial leaves, only 3-5 layers of
collenchyma are developed below the epidermis and the air-spaces in the centre
of the leaf-stalk have a diameter of over half a millimetre. These petioles are
consequently flexible, and cannot support the leaf-blade if taken out of the water.
The general form of the scale- and foliage-leaves, the segmentation of the latter
into petiole and blade, the configuration of the blade and the distribution of
the bundles in it are all the result of internal forces due to the specific constitution
of the protoplasm; but the thickness of the epidermal cells, the strength of the
mechanical tissue, and the length of the leaf-stalk, are determined by the depth
of the water-covering. The same thing is seen in the flowers; their structure
depends upon the specific constitution of the protoplasm, but the size of the
petals is determined by the temperature of the water.

The Meadow-grass Poa annua has a rapid growth; its haulms and leaf-sheaths
are round, the leaf-lamina is traversed by seven strands, the lower branches of the
inflorescence are single or paired but never whorled, and the spikelets of the
panicle are much compressed and egg-shaped in outline. These characters are
unalterable and are observed in Poa annua under all conditions. But when the
haulms growing in the gardens in the plain project beyond the short upmost leaf
the spikelets become 6-7-flowered, and have a pale green colour. When the plants
become perennial in alpine regions the haulms bend towards the ground and remain
so short that they do not reach above the highest foliage-leaf; the spikelets
develop only 3-4 flowers, and their glumes are dark violet on the surface and
brownish-yellow at the edge; thus these modifications are in relation to peculiarities
of situation (in the plain and alpine regions) as effect to cause, and are to be
ascribed to the influences of heat, light, and moisture, which act in various ways
according to the situation.

These alterations are always to the advantage of the plant. They make the

ARE THESE CHANGES IN FORM PERMANENT? 513

individual more resistant, support and protect its organs, and render it possible
for the separate parts to perform their work in spite of the necessarily altered
conditions. They seem to have the task of keeping the plant alive under very
different vital conditions, of promoting growth and the formation of offshoots
and fruit with the smallest possible expenditure, and they may therefore be
regarded as adaptations to the particular conditions of soil and climate.

The capacity for adaptation is of course founded in the specific constitution of
the protoplasm, and is very different in different species. One species may adapt
itself by appropriate alterations to the influence of bright light, submersion under
water, a dry atmosphere, &c., while another cannot do so. If the protoplasm of the
Flax (Linum usitatissimum) could manufacture as much anthocyanin in its green
tissue as the Summer Savory (Satureja hortensis) it would blossom and ripen its
fruits in alpine regions as this plant does, and would not succumb to the effect of
the strong light. If the protoplasm of the Common Bent-grass (Agrostis vulgaris)
were able to continue its constructive activity under water it would not perish as
soon as it is submerged, but would maintain itself like the stoloniferous species
(Agrostis stolonifera) by green stalks and leaves adapted to an aquatic habitat.
In short, the adaptability of each species is restricted within definite limits which
depend upon the specific constitution of the protoplasm and cannot be overstepped.

It is a matter of great import in the history of species whether modifications
in form effected by change of soil and climate are transmitted to the descendants,
and whether they can be inherited. This of course can only be ascertained by
experiments, and by experiments in which all possible sources of error have been
eliminated. This last remark is made advisedly, for the sources of error in such
experiments are very numerous. I will briefly indicate two which interfered with
some experiments I carried out in the years 1863 and 1864. It is not enough to
be careful that the seeds sown in the prepared experimental beds are all from the
same plant; care must also be taken to see that they are not the result of a hybrid
cross-fertilization. Some seeds taken in 1863 from a plant of Dianthus alpinus
growing in the Botanic Garden at Innsbruck, and sown in different soil in two
experimental beds, produced plants in soil free from lime, which, in their external
appearance, agreed with Dianthus deltoides. It seemed as if Dianthus alpinus, a
lover of limestone rock, had become transformed into Dianthus deltoides when
grown without lime. The seeds of the plant so like Dianthus deltoides were again
sown in soil without lime, but the resulting plants no longer resembled this species;
they showed themselves to be constant in their characteristics. The whole
experiment with Dianthus alpinus was then repeated, but this time the plants
on the clay soil without lime did not change, and I was obliged to conclude that.
the plant I had regarded as a stage in the transformation of Dianthus alpinus
into Dianthus deltoides was a hybrid of these two species. In order to be certain
about this a crossing between the two species was effected artificially. From the
resulting seed plants were actually grown which were exactly like those I had

regarded as transformations, and there was no longer any doubt that some of the
Vou. IT. 83

514 THE INFLUENCE OF MUTILATION ON THE FORM OF PLANTS.

stigmas of the Dianthus alpinus which had yielded the seeds for the first experi-
ment had been pollinated by insects with the pollen of Dianthus deltoides.

Mistakes often arise also from the fact that the young stages of many plants
are very different from the fully-grown specimens. Young Birches grown from the
seeds of Betula verrucosa bear leaves which are simply serrated, thickly covered
with hairs, and soft to the touch. They are deceptively like the leaves of adult
plants of Betula alba or pubescens. The leaves of the adult Betula verrucosa have
quite a different form; they are doubly serrated, smooth, and harsh to the touch.
These latter are the only form of leaf described in Botanical books for Betula
verrucosa. Anyone sowing the seeds from a grown tree, and watching them grow
up, with leaves of a different shape and surface, might easily think an actual
fundamental change had occurred, and might be tempted to regard the transforma-
tion as the direct effect of a change in external influences.

It is perhaps superfluous to state that due regard was paid to these possible
sources of error in the later series of cultural experiments, carried out during six
years in the Alpine garden on the Blaser (2195 metres), and for comparison in my
Villa Marilaun in the high-lying Tyrolese Gschnitzthal (1215 metres), in the
Botanic Garden at Innsbruck (569 metres), and in the Botanic Garden of the Vienna
University (180 metres); in no instance was any permanent or hereditary modifi-.... .
cation in form or colour observed.

Seeds of a plant grown in the valley when sown in the Alpine region produced
plants which exhibited the modifications described above. They were also mani-
fested by the descendants of these plants but only as long as they grew in the same
place as their parents. As soon as the seeds formed in the Alpine region were
again sown in the beds of the Innsbruck or Vienna Botanic Gardens the plants
raised from them immediately resumed the form and colour usual to that position.
The modifications of form and colour produced by change of soil and climate are
therefore not retained in the descendants; the characteristics which appear as the
expression of these changes are not permanent, and the individuals are to be there-
fore regarded as varieties, of which Linneus says in his Philosophia Botanica:
“Varietates tot sunt, quot differentes plantee ex ejusdem speciei semine sunt pro-
ducte. Varietas est Planta mutata a caussa accidentali: Climate, Solo, Calore,
Ventis, &e., reducitur itaque in Solo mutato.”

THE INFLUENCE OF MUTILATION ON THE FORM OF PLANTS.

When Birches and Firs grow up side by side in a wood-clearing, the crowns
of the Birches will overtop the Firs in some twenty years’ time, and this will
seriously interfere with the growth of the latter. With every blast of wind the
whip-like branches of the Birch strike against the upper shoots of the Firs, so
that these gradually wither and die off. A lateral branch of a Fir tree altering
its direction of growth and replacing the dead leader will, in its turn, soon be
scourged to death. The top of the Fir is permanently mutilated, and the injury

THE INFLUENCE OF MUTILATION ON THE FORM OF PLANTS. 515

can be recognized years after by the flattened form of the crown, so different
from the usual appearance, when the offending Birches have perhaps long dis-
appeared. Many other trees wage the same war with one another, the result
in each case being the mutilation and alteration of the form of the summit of
one of the trees. The Maple, for example, is either put quite hors de combat by
the long thorny branches of a neighbouring Gleditschia (Gleditschia triacanthos)
or else the crown becomes lop-sided owing to the destruction of the branches
on the side facing the Gleditschia.

The way in which the appearance of Firs, Larches, Beeches, and Ling is
altered by the attacks of ruminants, especially goats, was described in vol. i.
p. 445, and we may add here that Pines and Junipers are mutilated in the same
manner. The consequence is that lateral branches, which would not otherwise
develop, grow out in the following year from the base of the twigs which have
been bitten off Apparently no other alteration takes place in these plants.
But when huge boughs are broken off close to the ground by storms and the weight
of snow, when the tree-trunks of the forest are sacrificed to the wood-cutter’s
hatchet, and the stems of seedling trees and shrubs in the meadow to the mower’s
scythe, when all the young shoots are frozen by a night’s frost in spring, or when
all the leaves are devoured by caterpillars and the branches are left bare as in
winter—then the consequences are much more serious. In these cases new shoots
make their appearance either from “eyes” in the stem or from the reserve-buds
of the branches and twigs, or by buds produced by the roots below the ground.
The leaves of these shoots, or suckers, as they are called, differ very much from
those of the branches which have been broken, eaten, cut, or frozen off. The
leaves from the crown of the Aspen (Populus tremula) are stiff and smooth in
their adult condition; the circular blade is borne on a long petiole, and its margin
is coarsely notched and undulated. The lateral veins traversing the blade are
lost in a network near the edge in which no strong curved ribs occur. The leaves
of a sucker from the base of a mutilated stem, or from the root, are soft and
thickly covered on both sides with downy hairs; the heart-shaped blade is borne
on a short stalk, and the margin is beset with numerous upwardly-directed notched
teeth. The lateral veins of the blade merge near the edge of the leaf into a
network, in which strong curved ribs are plainly visible. The leaves from the
crown of the Oak (Quercus pedunculata) are deeply lobed and furnished with
two so-called auricles at the base; those of the suckers are quite entire or very
slightly lobed, with no auricles at the base. The leaves of the sucker of the
eommon Beech (Fagus sylvatica) are more or less plainly serrated at the edge,
while those of the topmost branches of the tree are quite entire. In the Black
Mulberry (Morus nigra), and in the Paper Mulberry (Broussonetia papyrifera),
the leaves of the sucker have a sinuous margin and are more or less deeply lobed,
but those of the tree-top are heart-shaped with notched margins and no lobes.
The leaves of the sucker of the Birch (Betula verrucosa) are simply serrated,
with velvety hairs; those on the crown of the tree are doubly serrated and

516 THE INFLUENCE OF MUTILATION ON THE FORM OF PLANTS.

smooth. The leaves on the suckers of the Round-eared Willow (Salia awrita)
are broadly ovate, fairly smooth, and the veins in the blade form a wide-meshed
reticulum; the leaves on non-mutilated branches are widened in the upper third,
strongly wrinkled, and covered with grey hairs, whilst the reticulum of the veins
is narrow-meshed. In Saliva rosmarinifolia, the leaves of the suckers are twice
or three times as broad as those of the normal branches, and they are smooth,
while those of ordinary branches are covered with silky hairs, and gleam like
silver. Hundreds of trees and shrubs might be mentioned in which there is a
distinct difference between the foliage of the suckers and of the normal branches
of the crown. But these few examples will suffice, and we will only mention
the Norway Maple (Acer platanoides), because the difference in the foliage-leaves
can be seen from the illustrations in vol. i. The leaves of the summit (see vol. i.
fig. 106, p. 416, and fig. 109, p. 419) are borne on long petioles, the blade is 5-7
lobed, and the lobes are short and beset with several pointed, tapering teeth.
The leaves of the suckers in this same Norway Maple are short-stalked, the blade
is slightly 3-lobed, and each lobe is triangular and without the elongated pointed
teeth. They exactly resemble the first foliage-leaves shown in vol. i. p. 9, fig. 1%

a
ta

This is also true of the leaves on the suckers of other woody plants. The shoots - -

developed from reserve buds, “eyes”, and the like, repeat to a certain extent the
beginning of the leafy stem, so that the phenomenon is only an exhibition of the
usual metamorphosis of the foliage-leaves. The difference between the older and
younger, 7.¢. lower and upper foliage-leaves, only seems strange because the two
kinds of leaf-forms are not usually seen simultaneously on one and the same
plant. By the time the crown of a tree has developed, the first (oldest) leaves
which adorned the young sapling have long disappeared. Many descriptive
Botanists, as a rule, only consider the foliage-leaves of the fully-grown trees
and bushes; some of them have hardly ever seen the first leaves of the commonest
trees, and when they do happen to come across them they regard them as an
extraordinary phenomenon, declare the shoots bearing them to be “bud variations”,
and draw bold and bewildering hypotheses from their appearance. This alteration
in form, however, has nothing to do with the formation of varieties, nor is it
dependent either upon the influence of the soil or upon the effect of climate.
Moreover, the form of leaf characteristic of the sucker is not possessed by the
secondary shoots which arise from the suckers; these are adorned with the same
foliage which occurs on the topmost branches of the tree.

Alterations in the scale-leaves as well as in the foliage are brought about by
mutilation of the branches. When the upper portions of Willow boughs with
their foliage-buds are cut off, leaving the lower portions with the buds of the
flower-catkins on them, the small pale scales at the base of the catkins change
into green foliage-leaves; the axis bearing these leaves elongates, and the catkins
then form the termination of a leafy shoot. Many Willows, e.g. Salia cinerea
and S. gramdifolia, by this metamorphosis assume a very unusual appearance.
In the following year the branches bearing the flower-catkins, if they are

seve eee

THE INFLUENCE OF MUTILATION ON THE FORM OF PLANTS. 517

not mutilated afresh, will again put out short catkin-stalks with small pale
scales.

Mutilation of herbaceous plants is caused by herbivorous animals, viz. insects
and mammals, and on a large scale by man when he mows the meadows and
cuts the crops and makes other necessary invasions on the natural vegetation in
the interests of husbandry. The alterations caused by these mutilations of the
foliage-leaf region are in the main the same as in woody plants. From the
remaining stumps of the stem lateral shoots arise whose first leaves are like the
first leaves of the seedling. Usually they are less divided and have fewer hairs
than the leaves on shoots of normal plants, and on this account they have a very
different character. In the floral region the effects of mutilation are twofold—
first the peduncles or the lateral axes which are terminated by inflorescences
elongate, and then the flowers become smaller. For example, when a vigorous
stalk of the Ox-eye Daisy (Chrysanthemum Leucanthemum) bearing a capitulum
is cut off close to the ground, long lank lateral stems develop from the axils of the
lowest remaining leaves, each one ending in a capitulum. The main stem is now
seen to be branched at its base, which is never the case in normal plants. If about
half the stalk of the common Foxglove is cut off in the spring long flower-racemes
will arise from the axils of the leaves just below the cut, but the flowers will be
only half as large as those which would have developed on the uncut main stem.
The stem of Althwa pallida rises a metre above the ground if its development is
not hindered, and forms fascicles of short-stalked flowers in the axils of the upper
leaves. If the stem is broken off lateral axes develop from the axils of the
remaining leaves, and bear little long-stalked flowers. Particularly good examples
are furnished by the annual weeds Delphiniwm Ajacis, Nigella arvensis, Stellera
Passerina, and the like, which grow up amongst cereals. Their main stems are
broken off when the corn is cut, and they then develop comparatively long
branches with small flowers from the remaining stumps. If only single flower-
buds, and not the whole inflorescences, are removed from a herbaceous plant whose
main stem terminates in a long raceme, so that each flower is cut away in turn
from below upwards just before it opens, the rachis of the raceme elongates
enormously and flower-buds are developed at its end which would certainly not
have unfolded had there been no mutilation. In the Red Foxglove, for example,
the rachis of the raceme which has been damaged in this way will grow to twice
its ordinary length, and twice as many flowers will be developed. The last and
highest flowers in such racemes, however, are only half the size of those which
arise on normal racemes.

We must now consider certain perennial meadow plants which when mown

‘down are stimulated by the mutilation to develop flower-stalks in the same year,

which would, in the normal course of things, not have flowered till the year follow-
ing. In Alpine valleys it is a very common thing for the flowers of the spring
plants Anemone vernalis, Geraniwm sylvaticum, Gentiana verna, Polygonum
Bistorta, Primula elatior and P. farinosa, Trollius Europeus, &e., to appear in

518 ALTERATION OF FORM BY PARASITIC FUNGI.

the autumn in meadows which have been mown in the spring. The flowers appear-
ing under these circumstances are remarkable for their small size. Their diameter
is at least a third smaller than that of the spring flowers. In conclusion we may
refer to the gardener’s artifice which has already been described (p. 453) of pro-
ducing perennial plants with wocdy stems from an annual Mignonette plant by
mutilation, We might also mention the dwarf shrubs and trees produced by
combined mutilation and grafting, especially the strange-looking little Ivy trees
obtained by grafting a flowering branch of Ivy on an erect stem a span high, and
the dwarf Conifers so much in favour with the Japanese.

Gardeners and descriptive Botanists have frequently determined and described
mutilated plants as other species, hybrids, or varieties. They are neither the one
nor the other. The peculiar appearance of the altered members resulting from
mutilation is exactly determined beforehand in each species; it is due to the specific
constitution of the species, and thus is part of its being. It is not produced by the
external influences ‘which lead to the formation of varieties, but is brought about.
by inherent necessity, quite independent of the influences of climate and soil.

ALTERATION OF FORM BY PARASITIC FUNGL

A considerable number of the trees and shrubs of Central and Southern Europe
bear bristling, much-branched structures on some of their boughs which, from a
distance, look like large birds’ nests or brooms, and which have been popularly
termed “witches’ brooms”. They are the outward and visible signs of a disease
from which the plants in question suffer, and, as their name testifies, their origin
was thought to be connected with witches. Traditionally witches have the power
of “wishing” harm to mankind, animals, and plants; and superstitious people, at
the sight of these peculiar pathological structures on the trees, may have started
the idea that the disease was caused by witches that they might have brooms
ready at hand for their midnight ride on the Brocken. Other plant diseases have
been ascribed to unusual conditions of weather, especially to long-continued rain
or great drought. It is not long since the discovery was made that most of the
diseases attacking trees, shrubs, and herbs are caused by Fungi, and that atmos-
pheric conditions are only concerned in the matter in so far as they hinder or
favour the establishment and development of these parasites.

All the Fungi in question are parasites. They penetrate into the tissues of the
host-plant and sooner or later cause the death of the affected part, and frequently
of the entire host-plant. The living protoplasm in the cells and tissues of the host
which is influenced by the parasite undergoes fundamental changes in its com-
position. Some of the cells are drained, their living protoplasm being consumed,
so to speak, and these cells are obviously marked for destruction. Others are not
killed, but changed. The metamorphosis occurs, in the first place, in the consti-
tution of the living protoplasts which have not yet completed their development,
the change much resembling that known as fermentation in fluid substances

TYPES OF FUNGAL GALLS. 519

(cf. vol. i, p. 508). In fermentation the chemical composition of the fluid is
altered, its chemical compounds are shaken, decomposed, and split up and new
compounds are formed by the action of the living Yeast cells. The same thing
happens here in the interior of the living plant in its turgid, meristematic tissue—
that is to say, in a group of protoplasts which still have the power of growing
at the expense of materials supplied them, of increasing in size, and of multiplying
by division. But these cells no longer behave as—in the absence of the parasite—
they would have done. Profoundly modified under the influence of the parasite,
but yet not killed, these cells, by their continued division, form tissues and organs
of new and unusual form; in other words, that part of the host which is invaded
but not killed by the parasite will continue to grow and increase in size, and in
consequence of the change which its protoplasm has experienced will assume a
different outward form.

These altered tissue-bodies produced by parasitic Fungi are called gall-structures.
They are usually characterized by an excessive growth known as hypertrophy, as
well as by their altered shape. The hypertrophy is without doubt caused by a
stimulus proceeding from the parasite. We may conclude that the significance
of the increased growth lies in the abundant supply of nourishment thus placed
at the disposal of the parasite, since the large quantity of food-material brought
for the excessive development of the hypertrophied growth connotes a large supply
for consumption by the parasite. In many cases, however, the hypertrophied tissue
merely forms a wall protecting the host against the further depredations of the
intruder. It then contains no nourishment for the use of the parasite, being built
up chiefly of corky cells, which the latter cannot consume or destroy. Such a tissue
might be compared to the so-called callus which grows up in plants in parts de-
prived of epidermis after an injury, or in other wounds, and gradually covers them
over with a protective layer.

The formation of the gall is often restricted to only a small portion of the
afflicted plant; in other cases whole leaves and branches, and sometimes even ex-
tensive shoots, become modified in shape. To get a general idea of the four types
of hypertrophied growths it will be best to take them one after the other in the
order mentioned, commencing with the simplest.

The simplest of these galls consist of a few degenerate and metamorphosed cells
in the centre of an extensive and unaltered tissue. They are produced chiefly by
parasites of the genera Rozella, Synchytriwm, Exobasidiwm, and Gymnosporan-
gium. Rozella septigena, one of the Chytridiex, develops swarm-spores which
attack the various species of the fungal genus Saprolegnia. They settle on the
tubular branches of the Saprolegnia at a place where it was just about to divide
and to produce swarm-spores of its own. In consequence of the invasion of the
parasite this does not take place, but the tubular cells which would have formed a
Saprolegnia-sporangium divide instead into short barrel-shaped cells, each of which
becomes a sporangium of Rozella septigena. In addition to this the infected cells
develop lateral outpushings which swell up spherically, and each contains a resting-

520 ALTERATION OF FORM BY PARASITIC FUNGI.

spore of the parasite. Parasitic species of Synchytrvwm cause a vesicular enlarge-
ment of single cells of the epidermis in the leaves of phanerogamic host-plants.
The not uncommon species Synchytrium Anemones and S. Taraxact produce only
a slight overarching, and the enlargement of the cells is hardly more than four
times, often only twice the usual size. But, by the influence of Synchytriwm
Myosotidis, hypertrophied epidermal cells rise up from the leaves of the Forget-
me-not (Myosotis) in the form of comparatively large, club-shaped, bottle-like, or
egg-shaped bladders of golden or reddish yellow colour, and each contains the
parasite, or rather its spores. The parts of the leaf attacked by Synchytrium
Myosotidis are also much thickened, the palisade cells and the air-containing
lacune of the spongy parenchyma (cf. vol. i. p. 279) disappear, and the tissue
consists entirely of large similarly-shaped cells which fit close to one another,
leaving no spaces between. In the gall caused by Synchytrium pilificwm on
Potentilla Tormentilla the much-enlarged cells in which the parasite settles are
overgrown by the adjoining hypertrophied cells, some of which rise up in the form
of hairs, and the whole new structure resembles a hairy wart.

A curious gall is produced by Exobasidium Vaccinit on a sharply-defined
portion of the folsage-leaves of the Alpine Rose (Rhododendron hirsutum and
ferrugineum). A spherical spongy body rises from a restricted portion of the
leaf, usually from the under side of the somewhat projecting midrib, sometimes
only as large as a pea, sometimes as big as a cherry, and occasionally even attaining
the dimensions of a small apple. It is yellow, but rosy-cheeked like an apple on
the side turned to the sunlight, and it reminds one of this fruit by its succulent
tissue and sweet taste. Indeed, these galls are sometimes called “Alpine Rose-
apples”. Their surface is covered with a bloom which is caused by the numerous
spores developed there and does not consist of wax like the bloom on an apple
rind. The neck joining the gall to the leaf is not more than 1-2 mm. across, and,
what is still more remarkable, except for this sharply-defined place of connection
the infected leaf is unaltered.

Galls produced by the Gymnosporangia on the leaves of the Mountain Ash,
Pear-tree, Rock-medlar, and other Pomez exhibit strange forms. One of them,
caused by Gymnosporangiwm conicum, on the foliage of the Rock-medlar (Aronia
rotundifolia), is represented in fig. 3577. It resembles a tubercle furnished with
horns projecting from the lower surface of the leaf. Microscopic examination
shows that the knob consists of the strangely metamorphosed spongy parenchyma
of the leaf. The intercellular spaces which normally contain air are quite filled
with the mycelial threads, and in the projecting portion of the tubercle, which
is very hard and almost cartilaginous, tubes are inserted which terminate blindly
below, where the spores of the parasite are developed, whilst above they are open
and fringed, thus allowing the spores to escape. These tubes look like horns to
the naked eye. Usually several galls occur together on the same leaf. They are
conspicuous at some distance on account of their colour. The chlorophyll is
destroyed wherever the mycelium of the parasite extends and a reddish-yellow

FUNGUS-GALLS ON STEMS. 521

colour takes its place, so that orange spots appear on the surface of the foliage,
contrasting vividly with the green of the unaltered portions of the leaf.

Galls rising from sharply defined parts of the stem are comparatively rare.
One of the most remarkable is produced on the stems of a Laurel (Laurus
Canarvensis) by the parasitic Hxobasidium Lauri. When it appears above the
bark it looks like an aérial root, but rapidly grows into a branched spongy body
8-12 cm. long similar in appearance to one of the Fungi belonging to the family
Clavariez (cf. fig. 195', p. 21). The galls produced by Entyloma Aschersonii and
Magnusii on the Composites Helichrysum arenariwm and Gnaphaliwm luteo-album

Fig. 357 —Fungus-galls.

1 Gall on the stem of the Juniper (Juniperus communis) produced by Gymnosporangium clavarieforme. 2 Gall on the leaves
of Aronia rotundifolia produced by Gy 3p gi i

take the form of outgrowths, varying from the size of a pea to that of a walnut,
developed from special spots on the root. Whether the spherical tubercles growing
on the root-fibres of many Leguminose, especially those of the Bird’s-foot Trefoil
(Lotus corniculatus), the Fenugreek (Trigonella fenwm-grecum), Lady’s-Fingers
(Anthyllis Vulneraria), Lupin (Lupinus variabilis), and the Liquorice (Glycyrrhiza
glabra) are to be regarded as true galls caused by the Bacteria-like organisms
invariably to be found in their interior is questionable. According to the most
recent investigations they are the outward expression of a case of symbiosis and
not of pure parasitism.

Gall developments which involve whole roots or rootlets are found on the Alder
(Alnus glutinosa), and on the Cabbage (Brassica oleracea). The gall which is
produced on Alder roots by Frankia Alni attains the size of a walnut and has a

522 ALTERATION OF FORM BY PARASITIC FUNGI.

curious gnarled appearance; all the fibres of the root-branch thicken in a club-like
or tuberous manner and become twisted and entangled with one another. The so-
called “ Fingers and Toes”, caused by the Myxomycete (Plasmodiophora Brassice),
is a gall-like hypertrophy on the root of Brassica oleracea, which not uncommonly
grows to the size of a man’s head.

Many woody plants have galls which alter the internal structure as well as the
outward appearance of large tracts of the stem. The parasites settle in the corti-
cal parenchyma, producing hypertrophy there, and afterwards the most varied
distortions and alterations in the wood of that region of the stem. The trunk,
branch, or twig becomes much swollen or knotted and the cortex rent and torn.
Resin or a gummy mucilage sometimes runs out of the rifts in the gall. As such a
parasite exercises its metamorphosing faculty for several years, the canker (as it
may be termed) increases in size continually. Sporangia of varied form and colour
appear annually on the affected places, and again disappear when they have shed
their spores. The part of the stem or branch above the cankerous cushion dwindles
and dies off sooner or later. It rarely happens that the tree or shrub is able to rid
itself of the parasite. Occasionally a growth of wood and cork from the adjoining
healthy part walls in the cankerous spot so that the parasite is destroyed. The
gall produced by Gymmnosporangium clavarieforme on the trunks and branches
of the common Juniper (Juniperus communis) is an example of this form (see
fig. 357"). From the hypertrophy there project in the early spring golden-
yellow tongues (shown in the figure) consisting of masses of spores embedded in
mucilage. Other similar growths are produced on species of Juniper by Gymno-
sporangvum conicum, G. Sabine, and G. tremelloides, but it would take too
long to describe their differences in detail. It is important to mention, however,
that each of these parasites has two stages of development, living on different
hosts, the hypertrophies as well as the associated spore-producing organs of the
parasite being different in the two cases. The “ Aicidium stage” produces carti-
laginous swellings (see p. 520) in definite spots on the foliage of various Pomer
(Aronia, Crategus, Pyrus, Sorbus), the “ Teleutospore stage” thickenings and
tuberous outgrowths on the trunks of Junipers (Juniperus communis, excelsa,
Sabina), and these parasites can travel from one host to the other in turn. (The
two stages on different hosts are shown in fig. 357; these are not of the same fungus,
but of nearly allied ones, and illustrate the point mentioned.)

The parasite Peziza Willkommii attacks the trunks and branches of the Larch
(Larix Europea), and produces the well-known Larch-disease or “Larch-canker”.
The parasite having gained access at some point on the stem or branch first pene-
trates the cortical parenchyma, and affects the cambium so as to prevent the
further development of wood in that place. The development of the wood on the
opposite side of the stem, ie. the formation of annual rings, may proceed for
several years, and in this way the attacked spot on the trunk takes the form of a
depression, which is rendered the more conspicuous should the wood and cortex
surrounding the parasite have undergone a greater thickening than usual. In

ENTIRE LEAVES AFFECTED BY FUNGI. 523

time the patch becomes a sunken, blistered hole from which resin flows; and every
year the fructifications appear above the cortex in the form of numerous little
cup-like structures which are white outside and scarlet-red in the concavity. As
the disease progresses the infected patch gradually spreads, and infected trunks and
branches can be easily distinguished at a distance. Towards the end of summer
the needles on the twigs above the canker turn yellow, while those on the healthy
branches are still a beautiful green. This premature discoloration is a sure sign
of the speedy death of the whole bough. A similar canker is produced on the

Fig. 358.—Various Galls.

1G@all on the bract-scales of the pistillate flowers of the Gray Alder (Alnus incana) produced by Exoascus Alni-incane.
2 Inflorescence of Valerianella carinata. % The same inflorescence with galls produced by a gall-mite, +4 Leaf rosette of
the House-leek (Sempervivwm hirtum): 5 Leaf rosette of the same plant which has been attacked by the fungus Endo-
phyllum Sempervivi and has become hypertrophied.

Silver Fir (Abies pectinata) by Acidiwm elatinwm, but instead of being only on
one side of the branch, as in the Larch, it forms a uniform swelling all round it.
Cankers of this kind are produced by a Bacterial organism (Bacillus amylovorus)
on fruit-trees (Apple, Pear, &c.), and on various trees belonging to the Amentifere
(Beeches, Hornbeams, Oaks, &c.) by the Fungus Nectria ditissima.

When whole leaves undergo hypertrophy of the kind we have particularly
remarkable changes of form. For example, the normal leaves forming the rosettes
of the House-leek (Sempervivum hirtwm; see fig. 358*) are broadly obovate in
form, being little more than twice as long as they are broad. The leaves of the
same plant after they have been attacked by the parasitic Endophyllum Semper-

524 ALTERATION OF FORM BY PARASITIC FUNGI.

wivi (see fig. 358°) are seven times as long as broad and linear in shape. They
stand erect, and are of a much paler colour than the healthy leaves. The Wood
Anemone (Anemone nemorosa) affords another example (see fig. 259, p. 229). It
spreads by creeping stems under the surface of the ground, and forms small
colonies in light thickets and in meadows. The plants consist partly of flowering
lateral shoots, and partly of foliage-leaves, which emerge above the ground from
the creeping underground stem. In normal leaves the erect petioles are all the
same length, and the leaflets are extended at about the same level. But when the
Aicidium stage of Puccinia fusca has settled on them this becomes altered. The
blades of the infected leaves tower over their healthy neighbours in consequence of
the elongation of their petioles, whilst their leaflets are smaller and less divided.
The length of the petiole in normal leaves is some 12-13 em., in hypertrophied
leaves 15-18 cm.; but the size of the altered segments, compared with those of
normal leaves, is as 5:7. Similar changes are observed in leaves of Soldanella
alpina when attacked by Puccinia Soldanelle. The petioles of the infected
leaves are 2-4 times as long as the normal ones, the blade is smaller and
hollowed like a spoon instead of being flat, and the colour is an ochreous yellow
instead of a dark green. The same alterations in the length of the petiole,
and, in the size and colouring of the- leaf-lamina, are produced in the leaves of
Alchemilla vulgaris by Uromyces Alchemille and in those of Phytewma orbi-
culare by Uromyces Phytewmatum. To this class belongs also the so-called
“curl” disease of Peach and Almond trees, produced by Exoascus deformans, and
rendered conspicuous by the considerable enlargement, undulation, and bladder-
“like expansion of the infected leaf-surface, which acquires generally a very brilliant
coloration.

Floral-leaves are comparatively seldom metamorphosed by Fungal parasites.
In the Alder (Alnus glutinosa and incana) the bracts of the pistillate flowers are
changed by Exoascus Alni-incane (=E. amentorum) into elongated purple-red
spatulate lobes much twisted and bent (see fig. 3581); Peronospora violacea some-
times causes the stamens to change into petal-like structures in the flowers of Knautia
arvensis, so that they then seem to be “double”; Ustilago Maydis causes a growth
of tissue in the pistillate flowers of the Maize, the result being that instead of grains
irregular cushion-like structures 7 cm. in diameter are produced. Taphrina awrea,
which settles on the pistillate flowers of Poplar (Populus alba and tremula) causes
the ovaries to form golden-yellow capsules more than twice the usual size. The
galls produced by Exoaseus Prwni on the ovaries of wild Plum, Bullace, Sloe, and
Bird Cherry (Prunus domestica, insititia, spinosa, Padus) belong also to this class.
The tissue of the ovary increases in size, but not in the same way as in fruit forma-
tion. The resulting body is flattened on two sides, brittle and yellow; the seed
inside is abortive, and a hollow space is left in its stead. The gall produced from
the ovary of Prunus domestica has the form of a rather curved pocket, which
looks as if it had been powdered outside with flour at the time the spores ripen.
These hypertrophies, which are popularly termed “pocket-plums”, “ bladder-plums”,

ENTIRE SHOOTS AFFECTED BY FUNGI, 525:

&e., fall off the trees at the end of May. They are eaten in many districts, but
have an insipid, sweetish taste.

Galls consisting of whole shoots, both the stem and its leaves being altered by the
parasite, are found principally on trees and shrubs, and only rarely on herbaceous
plants. Examples of the latter, however, are furnished by the metamorphosed
shoots of the Shepherd’s Purse (Capsella Bursa-pastoris) produced by Cystopus
candidus and Peronospora parasitica. Here the leaves, especially the floral-leaves,
as well as the ground-tissue of the stem undergo pronounced hypertrophy. The
petals, which measure only 2 mm. in length in a healthy plant, may become even
15 mm. long; the sepals also elongate, become fleshy and brittle, and are distorted
and crumpled in all manner of ways. Only six stamens are developed in normal
flowers, but in hypertrophied specimens there are often eight. The metamorphosis
produced by Uromyces Pisi in one of the Spurges, Huphorbia Cyparissias, is even
more remarkable. The stem elongates far beyond its usual dimensions, and the
leaves, which are crowded together on normal shoots, are thus separated by con-
siderable intervals. The distance between two adjoining successive leaves in the
healthy Huphorbia Cyparissias is only 0°5 mm., but in the hypertrophied specimens.
it becomes 2-3 mm. Infected shoots on an average are twice as high as healthy
ones. The foliage-leaves, which are thin, flexible, linear, and twelve times as long
as they are broad in the healthy plant, become, in the infected specimens, thick,
brittle, elliptical, and only 2-3 times as long as they are broad. The bluish-green
colour of the normal plant is changed into a yellow-ochre tint, and this contributes
not a little to the odd appearance of the plant. Affected plants are not uncommon
in Switzerland; a locality in which this disease has been very prevalent in recent
years being Saas-Fée in the Saas-thal. The metamorphoses produced on the shoots
of Periwinkles (Vinca herbacea, major, and minor) by the Uredospore-stage of
Puccinium Vinee and on shoots of Cirsiwm arvense by the Teleutospore-stage of
Puccinium suaveolens are very like those of the Ewphorbia just mentioned, since
the stem becomes much elongated and the leaves shorter, broader, yellow, and brittle.
When flowers are developed on these affected shoots, they are more or less abortive
and sickly, and no fruits or fertile seeds arise therefrom. Frequently the shoots
‘blossom prematurely. For example, we can at once detect by its elongated rosette-
leaves when Primula Clusiana and minima are infected by Uromyces Primule
imtegrifolic, and it may be observed when this is the case that the shoots do not
wait until the next spring to develop the flowers laid down in the summer, as usual,
but open them in the autumn of the same year instead.

The Cowberry (Vacciniwm Vitis-Idwa) is especially worthy of notice among
low woody plants, because two kinds of parasite attack its shoots. Melampsora
Geppertiana, in the Teleutospore-stage, causes a marked, gouty thickening in the
cortical parenchyma, which is converted into a spongy tissue; at first it is flesh-
coloured, but soon assumes a chestnut-brown tint. The stems elongate very much
and grow vertically upwards; and when several of them close together are thus
attacked they present a besom-like appearance. The foliage-leaves are much

526 ALTERATION OF FORM BY PARASITIC FUNGI.

farther apart than in the healthy plant on account of this stretching of the stem.
The lower leaves of the shoot are transformed into small fringed scales, and the
upper ones are so much shortened that their outline becomes almost circular. The
second parasite to which the Cowberry shoot is subject is Exobasidiwm Vaccinia (a
near ally of the already mentioned Hxobasidiwm Lauri, p. 521). The stem becomes
pale rose-red colour, and rather thickened and spongy, but it does not elongate
much more than usual; the leaves become blistered and curiously convex on the

under surface. The substance of the infected leaves becomes brittle and loses its
chlorophyll. A red tint appears in place of the green, especially on the upper
surface of the leaf, whilst the lower surface, on which the spores develop, looks as if
it had been dusted over with flour. Usually the buds develop prematurely on these
shoots, 7.¢. the buds which, under ordinary circumstances, would not develop until
the next year push out and form new shoots shortly after they have been laid down.
The axes of these shoots, however, remain short; their leaves are closely crowded,
red in colour, and sessile. From a distance the premature shoots look like large
double red flowers inserted in the dark green of the non-infected Cowberry bush.
The shoots which develop prematurely on the shrubs of the Bog Whortleberry
(Vaccinium uliginosum) by the action of Exobasidium Vaccinti are often met
with in alpine regions, and are even more noticeable on account of their fiery-red

ALTERATION OF FORM BY GALL-PRODUCING INSECTS. 527

colour. The Bearberry (Arctostaphylos Uva-wrsi), Ledum palustre, and the Marsh
Andromeda (Andromeda polifolia) are subject to similar metamorphoses at the
hands of Haobasidiwm Vaccinit, so that Vaccinium Vitis-Idea may be regarded
as typical of them.

When the shoots of the larger shrubs or trees are metamorphosed by parasitic
Fungi attacking their branches, we have the formation of the structures popularly
termed Witches’ brooms, which were mentioned at the beginning of this chapter.
The stimulus necessary for their formation is afforded in different plants by
different parasites; on Barberry bushes (Berberis vulgaris) by dicidiwm Magel-
henicum (to be distinguished from the common . berberidis), on the Gray
Alder (Alnus incana) by Exoascus epiphyllus, on the Hornbeam (Carpinus
Betulus) by Exoascus Carpini, on the Bullace (Prunus insititia) by Exoascus
imsititie, on other species of the genus Prunus by Exoascus Cerasi, on the
Birch (Betula verrucosa) by Eaoascus turgidus, on the Weymouth Pine (Pinus
Strobus) by Peridermiwm Strobi, and on the Silver Fir (Abies pectinata) by
Hediwm elatinum. Witches’ brooms also occur on the Mastic tree (Pistacia
Lentiscus), and on Beeches, Pines, Larches, Spruce Firs, &c., although hitherto
we have not been able to ascertain definitely what parasitic Fungi are the
cause in these cases. The Witches’ broom of the Silver Fir has been selected
and figured (see fig. 359) as a type of these peculiar structures. It always
grows on one of the horizontally projecting lateral branches of the Fir, and
raises its erect or curved twigs from the upper side, resembling, as it were, an
epiphyte growing on the bark of the horizontal bough. The twigs are grouped
in whorls and not in two rows, as usually happens in the lateral shoots of the
Silver Fir. They are all shortened and thickened, and remarkably soft and
pliable, because the cortical parenchyma has become spongy and the wood is
only slightly developed. The buds, which in healthy tissue are egg-shaped,
are almost spherical here. As in other instances of hypertrophied plant-members,
we have a precocious development, a so-called “prolepsis”, in these Witches’
brooms. The buds swell earlier and unfold earlier than those of healthy twigs.
The leaves remain short, yellow, somewhat crumpled, and fall off when a year
old, while those of normal twigs are long, linear, straight, dark green on the
upper side, and remain in position from 6-8 years. The growth of the twig
is restricted; it dies off in a few years, and then, inserted on the dark green
branches of the Silver Fir, remain the dry, bristling brooms, whose appearance
has stimulated the imagination of the peasantry and given rise to the superstitions
alluded to at the beginning of this chapter.

ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

“Certain members of the Arachnoidea, Diptera, and Hymenoptera, which
attack and penetrate the tissues of living plants and incite the formation of
peculiar excrescences, are known as gall-mites, gall-gnats, and gall-wasps. The

528 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

growths, like small rosy-cheeked apples, which occur on the foliage of Oaks,
popularly known as “oak-apples”, are amongst the best known. The terms
“gall” and “gall-apple” were used by writers in the sixteenth century, and (like
the Old English word galle, the French gaille, and the Italian galla) are derived

from the Latin word galla, used for these outgrowths by Pliny in his Natural

History. The sixteenth-century writers distinguish between “gall-nuts” and
“gall-apples”, meaning by the former the small hard outgrowths on the leaves
of Beech-trees. Afterwards the word gall was used for all the outgrowths
produced by animals on green living plants. More than that—the hypertrophies
described in the preceding chapter, produced in green host-plants by the various
families of Fungi, are also included under the term. It has been proposed recently
to substitute the word cecidium for gall, and to distinguish the excrescences as
myco-cecidia, nemato-cecidia, phyto-cecidia, diptero-cecidia, &c., according as they
owe their origin to Fungi, Thread-worms (Nematodes), Gall-mites (Phytoptus),
Gnats (Diptera), &c. A systematic classification of this sort, on the lines of
the classification of animals, might be of use to Zoologists, but to the Botanist its
value is only secondary. He must, as in other similar cases, keep to morphology as
the primary ground of classification, and has to arrange the structures according
to their agreement in development. Moreover, in a general review, it is necessary
to consider whether a whole group of plant-organs or one alone undergoes metamor-
phosis; and the starting-point of the outgrowth must also be ascertained; ie.
whether it is the foliage-leaves, floral-leaves, stems, or root-structures, &¢., which
are the head-quarters of the excrescence.

When the gall originating as the nest or temporary habitation of a single
animal or colony of animals is limited to a single plant organ it is said to be
simple; if, on the other hand, several plant organs are concerned in its production
it is said to be compound.

Simple galls may, for convenience of description, be divided into (1) Felt-
galls, (2) Mamtle-galls, and (8) Solid galls. The Felt-galls are chiefly due to
hypertrophied epidermal cells growing out into hairy coverings of various sorts
and shapes; Mantle and Solid galls, however, are rather more complicated.
In both cases insects are present in swellings of various descriptions, but there
is this essential distinction: The Mantle-gall is a hollow structure which,
though it may arise in various ways and assume a multiplicity of forms, always
has a portion of the surface of the affected organ for its lining—in other words,
it is a chamber formed by hypertrophied growth around the place occupied
by the insect. In the Solid gall, on the other hand, some spot is pierced by an
insect and the eggs deposited im the tissues (not on the surface), the punctured
spot forms a swelling with the larva inside, but the lining of the chamber is
in no sense a portion or development of the original surface of the organ affected.
Again, whilst in most mantle-galls the cavity of the gall is in Open communication
with the outside, and the insect can escape by this aperture (though this is not
invariably the case), in the solid gall there is not such opening, and the insect

FELT-GALLS. 529

has to bore its way out. Needless to say, of both these types there are numerous
modifications, but they fall into the two classes (of mantle and solid galls) according
to their mode of development.

The majority of felt-galls are produced by gall-mites. They form cottony or
felted growths on limited and sharply defined areas of green leaves and stems,
the surface of which is otherwise smooth, or possesses but few hairs. Some-
times they have the form of small tufts, bands, or stripes, sometimes of large spots
with irregular contour. In most instances the felt is situated on the under side
of the foliage-leaf, and the gall-mite usually prefers the projecting veins to the
green surface. In the Lime, Alder, Hornbeam, and Horse-Chestnut, the mites
usually establish themselves in the angles formed by the lateral strands where
they arise from the midrib, the projecting veins forming the framework for the
felted hairs. In the Bramble (Rubus) and the Burnet (Poteriwm) it sometimes
happens that the felt is continued down from the lamina to the leaf-stalk, and
occasionally the green cortex of the succulent twig is covered with felted bands
and spots. In some Brambles and Cinquefoils the sepals become furred by the
action of gall-mites, the usual consequence being that the outline also becomes
distorted. A swelling or slight hollowing of the green leaf-tissue very frequently
accompanies the formation of felted galls, in which case the hairy covering is
only visible on the concave side whilst the other remains smooth. This is most
remarkable in the foliage of the Avens (Gewm), Vine (V2tes), and Walnut-tree
(Juglans), where a dozen white or brown-felted pit-like depressions are sometimes
to be seen on the under side of a single leaf. The colour of the felted hairs is
white in the leaves of Beeches, Limes, Bird Cherry, Brambles, Cinquefoils
and Burnets, green in the common Maple, yellow in the Spindle-tree (Zuonymus
verrucosus), sulphur-yellow in Alnus orientalis and Black Poplar (Populus nigra),
carmine red at first and then violet in Alnus viridis and in the Birches (Betula
alba, carpatica, &c.), and brown in the Avens (Geum macrophyllum), Horse-
Chestnut (Zisculus Hippocastanwm), and in the Aspen (Populus tremula). The
felted galls which are light in their young stages usually take on a brown tint
afterwards. Microscopic investigation has shown that in the formation of felted
galls, the epidermal cells, originally tabular in shape and closely fitting, swell
out and become transformed into bent and twisted tubes generally shaped like
a club or retort, the stimulus being afforded by a minute gall-mite (Phytoptus).
These cells look like short hairs to the naked eye, and as they stand side by
side in large numbers the covering has a velvety or felted appearance. The mites
which produce the felt, deposit their eggs in the juicy hair-shaped cells, and their
young live on the materials contained in them. It should be mentioned that
formerly these velvety and felted coverings were regarded as Fungi, and were
described as distinct genera under the names Hrinewm and Phyllerium (e.g. the gall
known as Erinewm quercinum on the leaves of Quereus Cerris). To this group
belongs also the gall occurring on the Wood Meadow Grass (Poa nemoralis) con-

sisting of cells which resemble root-hairs, which is produced by the gnat Hormo-
Vo. IL. 84

530 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

myia Pow. The hair-shaped cells are epidermal, and spring from the stem above
the nodes; they break through the leaf-sheath which proceeds from the adjacent
node, and are arranged in two groups, which grow in opposite directions, so as to
wrap round the stem from the two sides. The whole hairy mass looks as if it had
been parted into two. At first the hairs are white; later they become light brown,
and when the gall is fully developed they have the form of brown felted strands,
wound round the stems and firmly inclosing the larva of the gnat in question.

A large number of simple galls are grouped together under the name of Mantle-
galls. The insects which give rise to them spend their lives on the surface of the
leaves, where they multiply and attach their eggs to the epidermis. A growth is
excited in certain layers of the cell-tissue by the stimulus which the animals
exercise on their place of settlement. Cavities are thus formed which serve as
dwellings for the animals and their brood, and which surround them like a pro-
tecting mantle. Mantle-galls may be divided according to their structure into
scroll-, pocket-, and covering-galls. Scroll-galls are caused by gall-mites, leaf-lice,
tree-hoppers, and flies, and usually occur on the blades, rarely on the petioles of the
leaves. The surface inhabited by these animals, which, in the ordinary course
of things would have spread out flatly, grows more luxuriantly on one side than
on the other, and the result is the formation of a scroll, ¢.e. of a chamber in which
the animals are hidden. It is always the side on which the animals live which
becomes concave, and the leaf is usually curled up lengthwise. In the Alpine
Rose (Rhododendron), Crane’s-bill (Geranium sanguinewm), and Orache (Atriplex
hastata, oblongifolia, &c.), it is the upper side of the leaf which is tenanted by the
insects, and is therefore the one to roll up; it is the lower side, however, in the
Buckthorn (Rhamnus cathartica) and the non-climbing species of Honeysuckle
(Lonicera alpigena, &.). In many instances the whole leaf-lamina is rolled up,
but more frequently the alteration is restricted to the edge of the leaf when the
margin appears to be bordered with a swollen hollow cushion often corrugated or
undulating. In the Alpine Rose (Rhododendron ferruginewm and hirsutwm) both
halves of the leaf-blade are rolled round (see figs. 3602 and 360°), but usually the
rolling is so slight that the gall has the form of a boat or hollow trough. Some-
times an alteration in the shape of the leaf accompanies the rolling. For example,
the foliage of the Abele (Populus alba) on which Pachypappa vesicalis establishes
itself when the leaves are very young, exhibits in addition to the rolling a deep
hollowing of the blade. Instead of the short blunt lobes, long pointed segments
are formed, which stand side by side when they are rolled up, and cross over one
another in many ways so that the mantle-gall on the hollow side is shut in by a
veritable lattice-work. The parts of the tissue brought into contact by the rolling
do not fuse together, and therefore the cavity in which the gall-producing insects
live is always in open communication with the exterior. In most cases the tissues
concerned are thickened, brittle, more or less devoid of chlorophyll, and yellow in
colour. Not infrequently a red pigment is formed in them, so that the outside of
the gall has a yellowish-red colour. The scroll-gall produced by the hemipterous

FORMS OF MANTLE-GALLS. 531

Trioza Rkamni on the margin of Buckthorn (Rhamnus cathartica) leaves is very
hard and thickened like cartilage. In many plants the epidermal cells lining the
gall elongate into hairy structures, as in the felt-galls previously described. Their
juicy contents are used as food by the young gall-mites. This is the case, for

. example, in the Alpine Rose (Rhododendron ferrugineum, ef. fig. 360°). Pocket-

galls are closely allied to the scroll-like forms. The tissue of the leaf-lamina or

Fig. 360.—Galls.

! Covering-galls on the petiole of the Black Poplar (Populus nigra) produced by Pemphigus spirotheca. 2 Scroll-galls on the
leaves of an Alpine Rose (Rhododendron ferruginewm) produced by gall-mites. % Transverse section of one of these galls.
#and 5 Bud-galls on the branchlets of the Wild Thyme (Thymus Serpyllum) produced by gall-mites. © Blister-like
galls on the leaf of the Red Currant (Ribes rubrum) produced by Myzus ribis. '7 Part of the leaf seen from below.
8 Vertical section of a portion of this gall. 9 Solid gall on the leaf of the Gray Willow (Salia incana) produced by Nematus
pedunculi, 10 The same gall cut open. 1 Part of the wall of this gall in vertical section. 1, 2, 4, 6, and 9 natural size;
Sand 6x 4; 8and7 x 8; 8 and 11 x 50.

petiole and sometimes that of the cortex in young twigs is subjected to a stimulus

where the animals (gall-mites, leaf-lice, diptera) settle, with the result that a hollow

protuberance arises whose excavated cavity serves as a temporary dwelling for the
insects. The protuberances exhibit a great variety of form and shape, and they
differ considerably in their internal structure. The following are the most notice-
able forms. First, the plaited galls. They form deep, plaited, sometimes twisted

channels in the leaf-tissue which open on the upper side by a narrow hole, and

532 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

project like weals on the lower surface of the leaf. The growing tissue which
forms the floor of the channel is yellow and often lined with short hairs. The
channel usually follows the course of the larger veins of the lamina, and some-
times actually traverses one. Plaited galls are produced by gall-mites. The best
known are those on the foliage of Carpinus Betulus, Clematis Flammula and C.
recta, and Ribes alpinum. Wrinkled galls come next to the plaited form. The
protuberance is here limited to the green tissue shut in by strong rib-like
projecting veins, and is only shallow; the upper side of the leaf has bulgings
and protuberances and the lower pits and cavities. The protuberances are
always developed in numbers close together, so that the leaf looks very
much wrinkled in that region. Examples of this form are furnished by the
wrinkled galls on the Elm (Ulmus campestris; see fig. 361 *) produced by the leaf-
louse Schizoneura Ulmi, and on the Red Currant (Ribes rubrum; see figs. 360 ® 7 8)
by another leaf-louse, Myzus ribis. In the latter several wrinkles are usually
united into large blister-like protuberances, red on the outside, and covered with
jointed cellular structures bearing glands which look to the naked eye like short
hairs. This form, though resembling certain felted galls, is distinguished from
them by the different form of the hairs arising in consequence of the stimulation.
In the Mouse-ear Hawkweed (Hieractwm Pilosella) leaf-fleas (Psyllodes) produce
minute protuberances with narrow mouths, which stand out from the lower side
turned towards the ground like small warts, and when they occur close together
give a corrugated appearance to the leaf. Hollow protuberances of this sort
arising upon restricted areas of the leaf-surface, and growing very actively, give
rise to bag or sack-like structures attached by a very narrow neck. From their
resemblance to a head such galls are sometimes termed capitate galls (Cephalonion).
In others, where the outgrowth is fairly thick-walled and in form horn-like, the
designation horn gall (Ceratonion) has been given. Between these forms numerous
intermediate forms exist which may be compared to pockets, bags, nails, &e.
Many of these galls project from both the upper and lower side of the leaf, as
though a nail had been driven through it—hence the last-mentioned name. The
capitate-gall of the Sloe (Prunus spinosa), caused by a gall-mite, projects almost
as much from the under as from the upper side, whilst the similar gall on the
foliage of the Bird Cherry (Prunus Padus) rises on the upper side as a long
pocket, but below only projects like a small wart. Many capitate and horn-like
galls are developed only on one side, and here again there is a very great variety.
When the protuberances are due to mites the cavity always opens on the lower
side of the leaf. Both the inner wall and mouth of the cavity are covered with
hairs, and sometimes the aperture seems to be actually plugged up by them. In
the bag-shaped protuberances produced by the leaf-louse Tetraneura Ulmni on
Elm leaves, a relatively large slit is formed just at the narrow part of the bag at
the moment when the insects leave the cavity (see fig. 361°), The external surface
of the protuberances caused by mites on the foliage of Alders (Alnus), Maples
(Acer), and Limes (Tilia) is smooth, in those of the Bird Cherry (Prunus Padus),

FORMS OF MANTLE-GALLS. 533

and Wayfaring Tree (Viburnum Lantana) ciliated, whilst in the inflated galls of
the Elm caused by the white woolly leaf-louse (Schizoneura lanuginosa), it is
covered with fine hairs like velvet. The capitate galls on the foliage of Maples,
Alders, and Limes, of the Guelder-rose and Strawberry, are scattered abundantly
over the whole lamina; in the Sloe they stand out chiefly from the margin of the
leaf, and in Elms they occur singly or in groups on its central portions. The size of
these galls depends upon their distribution. Those which rise in hundreds from the

Fig. 361.—Galls.

18 Solid galls on a Rose-leaf; 1 of Rhodites Rose, 2 of Rhodites Eglanteric, 3 of Rhodites spinosissime. 4 Wrinkled galls on
an Elm-leaf (Ulmus campestris) produced by Schizoneura Ulmi. 5 Purse galls on the same leaf, produced by Tetraneura
Ulmi. 6 Covering gall on the same leaf, produced by Tetraneura alba. 7 Solid galls on the leafof the Purple Willow
(Salix purpurea), produced by Nematus gallarum. 8 Solid galls on the leaves of the same Willow, produced by Nematus
vesicator.

same lamina have a diameter of 1-3 mm., while those which occur singly or in
small groups, often attain a diameter of 2-3 em.

Contrasting with these embossed or pocket-galls are the covering galls, forming
a third type of mantle-gall. In these, as in the embossed forms, the insects pro-
ducing the galls live in their cavities, but the course of development is quite
different in the two cases. The tissue round the place where an animal has settled
or where an egg has been fastened to the epidermis in this type begins to grow,
rising up in the form of a fleshy mound or wall which continues to grow until the
animal is wholly roofed in. The cavity in this case does not arise from an excava-
tion (as in the embossed or “pocket” type), but from an overarching of the tissue. The

534 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

external appearance of these galls is very varied. One of the simplest forms occurs
on the leaves of the Ash (Fraxinus excelsior, see fig. 362°), where it is produced
by the gall-gnat Diplosis botularia. The insect having laid its eggs in the chan-
nelled depressions above the leaf-veins, fleshy cushions arise on either side of the
groove which meet above and roof them over. The cushions of tissue forming the
roof do not fuse; their succulent edges merely meet, and when the time comes for
the gall-gnats to leave their temporary abode the tissue dries up and shrivels,

8

( pally
| D\\

Fig. 362.—Galls.

‘ Pine-apple gall on twigs of the Spruce Fir produced by the S i ieti:

; : pruce-gall Aphis (Chermes abietis). 2 Coverin

aoe of the se a sae oe. byramidalis) produced by Pemphigus bursarius, 3 oa galls rene jal
unus excelsior) produced by Diplosis botularia. 4 Covering gall on Pistacia (Pistacia Lenti:

r a ; e tiscus) produced by Pem-
phigus cornicularius. 5 Solid galls on the cortex of Duvaua longifoli rioaey

I ngifolia produced by Cecidoses Eremii 6 itudi
section of one these galls. 7 Capsule galls on the leaf of the Turkey Oak (Quercus Cerris) praduien segaaroee sce.

leaving a gaping slit as shown in fig. 362°. The same thing happens on the leaves
or rather leaf-veins of the Stinging-nettle (Urtica dioica) and of the Alder (Alnus
glutinosa), where the galls are produced by gall-gnats (Cecidomyia urtice, alni)
and on the midrib of Elm leaves (Ulmus campestris; see fig. 361°), where the alls
are produced by a leaf-louse (Tetranewra alba). :

The so-called turpentine gall-apples (Carobe di Giude; see fig. 3624), which

SOLID GALLS. 535

are caused by leaf-lice on various species of Pistacia, also belong to the covering
class. The rudiment of a foliage-leaf, which in the normal course of events would
have developed into a pinnate leaf with dark-green elliptical leaflets, grows out
into a pod-like structure not unlike a locust-bean (fruit of Ceratonia Siliqua).
These galls are longitudinally grooved, and it can be seen more or less distinctly
that the furrows correspond to the edges of the leaflets, only here the leaflets
have become wrapped in, very much thickened and elongated, and fused with one
another. In the cavity inclosed by the fused leaflets lives a colony of leaf-lice
(Pemphigus cornicularius) which have developed under the protection of the gall.
When it is time for them to leave the cavity the top of the pod opens by the
separation and bending back of the tips of the fused leaflets which form the wall
of the cavity (see fig. 362‘). The Chinese galls of commerce, produced also by
Aphides (on Rhus semialata), develop much in the same way. They are hollow,
irregularly pear-shaped structures with thin walls covered externally with a gray
down. Two other covering galls which deserve special mention on account of their
form arise on the petioles of the Poplar, particularly on the species Populus nigra,
pyramidalis, and dilatata. The one, caused by a leaf-louse, Pemphigus bursarius
(see fig. 362 *), consists of a smooth expansion, red in colour externally, on the upper
side of the grooved petiole. If the local swelling be cut through it is seen to be
hollow, the cavity in which the leaf-lice live being shut in by thick fleshy walls.
The fleshy tissue of the walls is formed by a growth of the cells round the place
where the gall-producing insect has settled. A hole is formed at a point remote
from the petiole (where the growing tissue met and formed a dome) as soon as
the time comes for the inhabitants to make their exit. This is bordered by thick
lips as shown in fig. 362* The other gall which appears on Poplar petioles, pro-
duced by Pemphigus spirotheca, is formed by the thickening of the edges of the
grooved petiole, which rise up as fleshy cushions and meet above the depression.
At the same time the petiole undergoes a spiral twisting, and a gall is thus pro-
duced whose cavity is spirally twisted like the interior of a snail’s shell. The
thickened edges of the petiole do not fuse; at first they fit close to one another,
but later on they separate, and a spiral hole out of which the white, downy leaf-
louse can creep is the result (see fig. 360’, p. 531).

We will now leave the mantle-galls and pass on to a consideration of the solid
or tubercular galls. These are of the nature of swellings of limited size on single
plant-organs, and are produced by insects which pierce the plant-tissue and lay
their eggs in the wound. In this way either the epidermis of the chosen spot alone
is injured, or the egg is inserted into the deeper-lying tissues. In both cases an
active cell-division is incited in the neighbourhood of the injury. If, however, the
egg has only been deposited in the epidermis, the larva which arises from it must
penetrate into the interior of the now swollen tissue; when the egg is laid at once
deep down this farther penetration on the part of the larva is of course unnecessary.
The cavity in which the larvee dwell may be called the larval chamber, and this sort
of gall can be classified according to the number of chambers which it contains,

536 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

whether only one or several (uf. figs. 363° and 363 7), A great variety is met with
in the structure of the wall of the larval chamber. It always has a layer of juicy,
thin-walled cells immediately surrounding the egg, known as the medulla or pith
of the gall, and an outer layer which surrounds the inner like a skin or bark
(see fig. 3607). In most instances a third layer is inserted between them which
consists of very hard cells forming a protective layer. It should also be noted that
the layers of the wall of the gall separate in many instances, so that it is possible
to distinguish an “inner” and an “outer gall”. The gall-pith furnishes the larva
with food when it emerges from the egg, and for this purpose the cells are stored
with nourishing substances. The development of the pith takes place with great
rapidity, and begins as soon as the egg has been laid in the tissue. The larva when
hatched finds the inner wall of the chamber which has been fitted for its temporary
abode always provided with the necessary food, and it immediately attacks and
devours the juicy tissue with great avidity. The cells which are demolished,
wonderful to relate, are replaced almost at once. The cells of the gall-pith remain
capable of division as long as the larva in the chamber requires food, and the
surface cells which have been devoured in the gall-chamber are soon replaced by
new cells from below, just as grass which has been mown down or cropped by
cattle in a meadow sends up new stems and leaves. The spheroidal gall arising
on the leaves of Salia incana (ef. fig. 360°) has only one chamber, and here the
larva lives at the expense of the starch and other food-materials contained in the
extremely thin-walled cells which constitute the gall-pith (fig. 360"). The larva
traverses the chamber in a circle, beginning the destruction of the cells at a certain
place and eating on as it continues its peregrination (fig. 3601°). New cells have
already been formed for its nourishment by the time it again reaches the place
from which it started.

The hard and cortical layers are modified in very many ways as protective
measures against the drying up of the gall in summer on the one hand, and
against the attacks of birds and larger animals on the other. For the latter
purpose the cortical layer is often fashioned like the pericarps of fruits which
have to protect the seeds (cf. p. 442). This also explains the bitter substances,
hard skin, furry coat, bristling processes, and numerous other protective structures
which are developed in and on galls just as on pericarps, and which contribute
not a little to the remarkable similarity between galls and fruits. Many peculiar
developments on the surface of these fruit-like galls cannot indeed be explained
in this way, but, as in so many other cases, we conclude that they must afford
some other advantage concerning which our understanding is still at fault.

The external similarity between fruits and solid galls affords us useful points
for classifying the latter into groups, which we may name berry-like, plum-like,
apple-like, nut-like, capsule-like, &. The currant gall produced by Spathegaster
baccarum on the male catkins of the Oak has not only the form and size of a Red
Currant berry, but is also succulent and coloured red, and when several of these
galls are formed on the same inflorescence it looks at first sight just as if racemes

SOLID GALLS. 5387

of red currants had been borne by some chance or other on Oak twigs. The galls
produced by the Beech-gall gnat (Hormomyia fagi) on the foliage of the Beech
resemble small plums, being surrounded by a hard layer which consists of a stone
kernel and a layer of cells which might be compared to the fleshy part of a plum.
The galls caused by gall-wasps of the genus Aulaz on the nutlets of many
Labiatz, especially on Nepeta Pannonica and Salvia officinalis also assume the
form of stone-fruits. The insect lays its eggs in one of the four nutlets developed
at the base of each flower; and within a week this grows into a smooth greenish-
yellow ball which has the external appearance of an unripe cherry. A section
through it shows that it possesses also the same structure as a cherry, plum, or
stone-fruit in general. The succulent outer layer surrounds a hard stony kernel,
but in the cavity of the kernel there lies the white larva of the gall-producer
instead of the seed. These galls fall off just like fruits in July, and lie on the
ground during the winter; and the mature insect does not bite an opening in
the wall of the gall through which it can emerge until the following year. It
has been already remarked at the beginning of this section how strong is the
resemblance between apple-fruits and the spherical oak-galls, known as oak-apples,
which are produced by various Cynipedes (see fig. 364°), together with the small
red-cheeked galls produced by Rhodites Eglanterie and Nematus gallarwm (see
figs. 361? and 3617) on Rose and Willow leaves respectively. Pith-galls which
resemble certain dry fruits are very common. Those produced on the green cortex
of young Oak twigs by Aphilothria Sieboldi (see fig. 3641) remind one of the
fruits of species of Metrosideros, those produced by Neuroterus lanuginosus and
Spathegaster tricolor on the leaves of the Turkey Oak (Quercus Cerris; see figs.
364" and 364714) have a decided similarity to the indehiscent fruits of the Wood-
ruff and of the Goose-grass (Asperula odorata and Galium Aparine). The
“spangle” galls produced on Oak-leaves by the gall-wasps Newroterus fumi-
pennis and numismatis resemble the fruits of Omphalodes (see figs. 364" and
36418), and the galls on the leaves of Duvauwa longifolia produced by an insect
Cecidoses Eremita have the form of a capsule which opens by an operculum (see
figs. 362° and 362°). Like fruits these galls may appear in all imaginable con-
ditions with smooth, warted, or rugged surfaces, or covered with woolly or velvety
hairs, with bristles or spines, fringes or claws, or even with moss-like outgrowths.
The galls with moss-like covering occurring on the Wild Rose have been known
from remote times as Bedeguars. They are caused by the Rose-gall wasp (Rhodites
Rose), which deposits its pointed, sometimes hooked eggs early in the spring in
the substance of an undeveloped leaf while it is still folded up in the bud. The
growth of the leaf becomes altered, the first sign being the development of
numerous hairs. The larvee, when they creep out of the eggs, penetrate deeper
into the tissue of the leaf, and it swells out into a solid gall contaming as many
chambers as there are larve. Hairs and fringes continue to form on the exterior
till those curious structures are formed which were said to have the power of
inducing a peaceful sleep when laid under the pillow. Usually the stalks of the

538 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

young bud-leaves are pierced and then the upper portion of the leaf becomes
atrophied. More rarely is the egg laid in the epidermis of one of the leaflets,
in which cage the leaves attain their normal size and only this particular leaflet
is decorated with little bedeguars, as shown in fig. 3611. When the petioles of
three young leaf-rudiments are pierced simultaneously, as often happens, three
single galls are produced close together on a shortened axis, and the whole structure
may then attain the size of a pine-cone. ;

The portion of meristematic tissue which is pierced’ by the insect when it
deposits its eggs sometimes remains an open passage; but more often a corky
tissue is formed at the wounded spot which quite closes the chamber wherein the
larva dwells. Under these circumstances the insect when it emerges must itself
make an exit-passage from the gall, and this it does by biting a hole through
it with its mandibles (see fig. 364°). The gall-wasps (Cynipedes) invariably leave
the chamber which has hitherto served them both as a safe habitation and as
an inexhaustible storehouse in this way. This does not occur, however, in some
of those solid galls which owe their origin to gall-gnats of the genera Hormomyia,
Diplosis, and Cecidomyia, for example, in those on the leaf-blade and petiole of
the Aspen (Populus tremula) produced by Diplosis tremule and on the leaves
of Willows (Salia Caprea, cinerea, grandifolia) by Hormomyia Capree. Here
the exit-passage is formed during the development of the pith. The gall consists,
as in most other solid galls, of a pith, a hard layer, and an epidermis, but the
enormously developed pith and the hard layer do not quite entirely surround the
small larval chamber, they leave a small aperture on the part of the gall which
is most arched. As long as the epidermis stretches over this place the mouth
of the passage is of course not evident, but when the time comes for the insect
to quit the chamber a gaping slit is spontaneously formed in the tense epidermis.
In many instances the insect or the pupa as it pushes forward may break through
the thin skin. A peculiar closure which might be compared to a lid is formed
in the common solid galls which are produced so abundantly on Beech leaves
by Hormomyia fagi and which have been already alluded to. Just as the pupa
of many Lepidoptera projects out of the hole in the cocoon which the caterpillar
has spun for it far enough to allow the insect to fly away uninjured when it
emerges, so that of Hormomyia fagi presses through the lid-like closure at the base
of the gall, and the winged insect comes out leaving the chrysalis-case behind it.

The opening of some solid galls, which resemble operculate capsules, and which
may be termed capsule-galls, is especially remarkable and requires a more de-
tailed description. As long as the larva or grub can remain and obtain food in
the larval chamber the gall is completely closed, but when the time approaches
for it to move its quarters and to enter the pupal stage in the ground a circular
line of separation is formed in the tissue, and the part of the wall within the
circle comes away as a lid. The process is seen very prettily in the gall produced
on the leaves of the Turkey Oak (Quercus Cerris) by the gall-gnat Cecidomyia
cerris (see fig. 362"). In its closed condition the gall is a firm rounded chamber

DEHISCENCE OF CERTAIN GALLS. 539

so embedded in the leaf that it projects on the upper side as a small pointed
cone, and on the lower side as a disc covered with a thick coating of hairs. In
the autumn a circular piece like a lid becomes detached from the lower side of
the chamber. It corresponds exactly with the extent of the hairy disc, and is
so sharply defined that it looks as if it had been cut out with a knife (see figs.
362° and 362°). The operculum falls off, and the larva which had emerged from
the egg and which has lived all the summer in the gall-chamber tumbles out
and makes its way into the ground, where it begins to spin. By the next spring
it has entered the pupal stage, and the gall-gnat creeps out of the chrysalis
about May.

Still more peculiar are the galls produced by Cecidoses Eremita on the green

Fig. 363.—Solid Galls.

1 Capsule-like galls on a leaf of the Broad-leaved Lime (Tilia grandifolia) produced by Hormomyia Réaumuriana. 2 Longi-
tudinal section through one of the galls, showing the maggot in the interior; x 2. 8% Longitudinal section through a
capsule gall from which the inner gall is just being extruded; x 2. 4 Outer gall after the extrusion of the inner gall; x2.
5 Inner gall at the moment when the operculum is thrown off; x 2. § Capsule-galls on the leaf of a Brazilian species of
Celastrus. 7 Longitudinal section through one of these galls; x 2. 8 The same after the inner gall has fallen out; x 2.
1 and 6 natural size. :

cortical tissue of young twigs of Duvaua longifolia, a South American represen-
tative of the Anacardiacee (see figs. 362° and 362°). The gall is quite spherical
and very hard, and its large cavity conceals the caterpillar which has been
hatched from the egg. When the time draws near for the formation of the pupa,
a plug with a projecting rim is developed on the side of the gall furthest from
its point of attachment. When the plug is pushed out a circular hole is left
which leads into the gall-chamber through which the caterpillar escapes from its
dwelling. People who have not seen these galls with their own eyes might almost
think this description was the work of imagination. And yet there are still more
wonderful forms in this class of gall-structures. On the foliage of the Lime (Tilia
grandifolia) a growth arises round the eggs of the gall-gnat Hormomyia Réau-
muriana which at first has the form of a flat lens inserted in the green tissue of
the blade, but which gradually enlarges until it projects from the upper side like a

540 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

blunt cone and from the lower as a hemispherical wart. The gall-chamber is
inhabited by the maggot of the gall-gnat. The top of the conical part loses its
colour in July and becomes yellow and brown, and a rim is formed around its
summit. On cutting a vertical section through the gall at this stage it is seen that
the tissue forming the wall of the chamber consists of two parts (see figs. 363”).
The inner layer, which contains the maggot, is surrounded by an outer one which
gradually passes into the green substance of the leaf and extends up to the rim just
mentioned. The whole structure has separated into an “outer” and an “inner”
gall, the inner gall resembling an egg lying in an egg-cup (¢/f. fig. 363”). During
the summer the inner gall separates completely from the outer and is actually
thrown off by it. For the accomplishment of this the tissue of the outer gall swells
up very much, so that it exercises a pressure on the inner gall which is shaped not
unlike a cone, somewhat narrower below than at the top (see fig. 363%). The
extruded inner gall falls on the ground below the Lime-tree and assumes a dark-
brown colour; the outer gall remains as a little crater embedded in the leaf-blade
and ultimately shrivels up (cf. figs. 363! and 3634). The detached inner gall is
smooth at the blunt and previously upper extremity, and striated at the other; it is
not unlike a detached composite-fruit. The gall-gnat within feeds for a little time
longer on the succulent lining, and then rests through the winter; in the spring it
makes its escape. To do this it bites a ring-shaped groove below the conical top of
the gall and presses against the roof, which, owing to the breaking of the tissues
around the ring, comes away like a lid (see fig. 363°). A similar state of affairs
prevails in a gall formed on the foliage of a Brazilian species of Celastrus (see
figs. 363 ® 7 §), but here the inner gall (which comes away) has several chambers, and
the outer gall has the form of a cup set in the green blade.

The place of origin of all these solid galls depends of course upon the insects
producing them. These are usually very fastidious about the place where they
will lay their eggs, and it is truly astonishing with what care they search out spots
difficult of access, and at once favourably situated as regards food supply and
likely to afford a safe habitation for their offspring during the larval stages. The
small gall-wasp Blastophaga grossorwm lays its eggs in the ovaries of the “ gall-
flowers” in the interior of the figs of Ficus Carica (see p. 160 and figs. 240 * and
2407, p. 157). The gall-wasps Andricus amenti and Neuroterus Schlechtendali
deposit them in the stamens of the Turkey Oak; the gall-wasp Cynips caput-
medusce lays hers in the side of the bract-scales which surround the pistillate
flowers of the Oak (Quercus sessiliflora and pubescens), and so produces a gall with
innumerable stiff-pointed fringes entangled with one another which ward off the
attacks of other animals (see fig. 364"). Countless gall-producing insects deposit
their eggs on the lower side of foliage leaves, some preferring the lamina, others
the veins. Andricus cwrvator prefers the margin of Oak leaves, Diplosis tremule
the petiole of the Aspen at its junction with the blade. Several gall-wasps, as, for
example, Andricus estivalis and Andricus grossularice, seek out the floral recep-
tacle in the male catkins of the Turkey Oak for the deposition of their eggs, whilst

ALTERATION OF FORM BY GALL-PRODUCING INSECTS. 541

several Cynipedes, e.g. Aphilotrix Sieboldi (see fig. 364) lay their eggs in the green
cortex of the young twigs. Solid galls are very rare on roots, but they do occur

Fig. 364.—Various Oak-galls.

1 Solid galls on the cortex produced by Aphilothria Siebolut. 2 Bud-gall from a foliage-bud produced by Cynips Hartigii.
8 Solid galls on an Oak twig produced by Cynips Kollari. 4 One of these galls cut in half. 5 Bud-galls from foliage-buds
produced by Cynips lucida. §& One of these galls cut in half. 7 Leafy bud-galls produced by Aphilothria gemme.
8 Bud-galls from foliage-buds produced by Cynips polycera. 9% Longitudinal section through one of these galls. 10 Gall
on the pericarp of Quercus pubescens produced by Cynips caput-meduse. 11-14 Spangle galls on a leaf of the Turkey Oak
(Quercus Cerris); 11 produced by Neuroterus lanuginosus; 12 by Neuroterus numismatis; 18 by Neuroterus fumipennis ;

14 by Spathegaster tricolor.

in this situation in the oak, being produced by the gall-wasps Aphilothria radicis
and Biorhiza aptera.

542 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

When several organs of a plant immediately adjacent to one another are con-
cerned in the production of a gall it is said to be compound. Compound galls are
for the most part produced from buds, and they are all comprehended under the
general name of Bud-galls. They are extraordinarily varied in their characters,
some being merely abbreviated axes clothed with scale-like leaves, in others only
the base of the shoot is involved and above the gall it continues its growth quite
normally, whilst in others again the axial portion of the structure is much swollen,
and the leaves hardly represented at all. It is difficult to give any satisfactory
classification of these bud-galls; still, for the sake of arranging our facts, we may
distinguish these types, viz.:—the ordinary bud-gall, the cuckoo-gall, and cluster-
gall. Ordinary bud-galls involve several, often all, the members of a shoot. The
axis of the shoot is always deformed and abnormally thickened. The swollen portion
contains in its interior one or several larval chambers surrounded by a pith-like
layer. Two varieties of ordinary bud-gall may be distinguished. The first is leafless;
no leaves are present, or, more correctly, they are transformed into tubercles, pegs,
and knobs which merge insensibly into the swollen axis which contains the larval
chamber. The second possesses leaves, the gall being covered with scale-like bracts
or more or less fully developed green foliage-leaves. Amongst the leafless bud-galls
the most interesting are those which are armed with special means of protection
against the attacks of animals on the watch for the larve of the gall-wasps. The
gall shown in figs. 364° and 364°, produced by Cynips polycera on the leaf-buds of
Quercus pubescens and sessiliflora, which to a certain extent affects a whole lateral
shoot, has the form of a young Medlar fruit, and on it may be seen 3-5 metamor-
phosed leaf-structures projecting as stiff-pointed pegs which gradually pass into the
tissue of the shoot axis. This gall is one-chambered, and the tissue of the wall has
separated into an outer layer and an inner spherical pithy gall. The gall shown in fig.
364? is produced by the gall-wasp Cynips Hartigii which lays an egg in the middle
of the leaf-bud of the Oak (Quercus sessilaflora). The bud does not develop into a
leafy shoot, but into a small one-chambered gall with large tooth-like or club-like
processes which represent metamorphosed leaves. The thickened angular ends of
these projections fit closely to one another so as to form a sort of second outer coat
to the gall-chamber through which hostile ichneumon-flies cannot penetrate. The
gall much resembles the cone-fruit of a Cypress in the arrangement and form of its
superficial processes. The galls produced from the buds of various Oaks (Quercus
pendulina, sessiliflora, pubescens) by the gall-wasp Cynips lucida are still more
peculiar (see figs. 364° and 864°). They contain several larval chambers with
abundant pithy tissue, whilst innumerable slender processes resembling limed twigs
in being very sticky on the capitate thickened end project from their exterior.
Ichneumon-flies and other animals hostile to the gall-producers take good care not.
to come into contact with these spikes which are to be regarded probably as trans-
formed leaves springing from the swollen axis. Among the galls produced, from
leaf-buds belonging to this group there are some in which the leaves are merely
indicated as tubercles. This is the case, for example, in the many-chambered,

BUD-GALLS. 543

spongy gall, red-cheeked on the sunny side but pale elsewhere, which is produced
on the tips of the branches of the Oak by the gall-wasp Dryoterus terminalis, and
looks very like a potato in shape. The leaves are only represented by small ill-
defined knobs and ridges, just as in the potato. To this class of galls belongs
also that to which the term “nut” is popularly applied, and even in commerce, the
name has been transferred from this to the whole of the first group of compound
galls (bud-galls). The “nut” is produced on the Oak by Cynips calicis as an
angular and irregularly-grooved gall which originates at the end of a flower axis,
and the cupule formed of several bract-scales as well as the ovaries are concerned
in the growth. This class of galls also includes the irregular blunt swellings on
Aspen twigs (Populus tremula), which are caused by the larva of a beetle (Saperda
populnea), and in addition the many-chambered woody “canker cushions” as large
as a nut which are produced on the branches of Willows by Nematus medullaris.

The gall shown in fig. 3647, which arises on various Oaks (Quercus pedunculata,
sessiliflora, pubescens) by the action of the gall-wasp, Aphilothria gemma, may be
selected as a type of leafy bud-galls. It resembles the cone of a Hop or Larch,
and is developed from a foliage-bud. It has a much-abbreviated swollen axis, whose
tissue separates into an inner and outer gall, beset with numerous dry, brown lan-
ceolate hairy scales having the form of bract-scales. Bud-galls which are covered
with green foliage-leaves are produced by the gall-wasp Andricus inflator on the
Oak, but they are more commonly met with on herbaceous plants, e.g. by Urophora
cardui on Cirsiwm arvense, by Diastrophus Scabiose on several Knapweeds (Cen-
taurea alpestris, C. Badensis, C. Scabiosa), by Aulax Hieracw on various Hawkweeds
(Hieracium murorum, sylvaticum, tridentatum, &c.). Usually the foliage-leaves
are stunted, and not infrequently the blades of some of them are quite obliterated,
so that the gall in that region is only furnished with scaly leaf-sheaths. A Sage
growing in the Isle of Crete so often bears leafy bud-galls resembling a small
Quince-apple, produced by a species of Aulax, that Linnzus called it Salvia pomt-
fera. The stem of this Sage is swollen out like a ball, and the spherical mass,
covered with a gray felt of hairs on the exterior, is surmounted at the top with a
group of small wrinkled leaves, which look like the persistent calyx of a Quince-
apple. The best known and most widely distributed of these forms, found on the
Hawkweeds named above, consist of knob-like swellings of the stem. The larval
chamber is situated inside the enlarged pith, the ring of vascular bundles, which has
undergone much shifting, forms the protective layer, and the cortex of the affected
region of the stem forms the cortical layer of the gall. The epidermis is densely
covered with hairs.

Leaving the galls which consist of modified foliage-buds, we pass on to such as
consist of metamorphosed flower-buds. They arise from flower-buds in which small
gall-gnats have laid their eggs. The larva hatched from the egg lives in the cavity
of the ovary, or.in one of its loculi when there are several, and this space, therefore,
becomes the larval chamber. The corolla, which envelops the ovary in the flower-
bud, remains closed, like a cap on the top of the larval chamber. The calyx becomes

544 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

inflated, enlarged, and sometimes fleshy. The whole gall resembles a bud or small
bulb; it is not unlike one of those bulbils which so often arise instead of flowers
on the flowering axis of certain species of Allium. They occur especially on the
Bird’s-foot Trefoil (Lotus corniculatus), where they are produced by the gall-gnat
Cecidomyia Loti, on the various species of Mullein (Verbascum Austriacum,
nigrum, Lychnitis, &e.) by Cecidomyia Verbasci, on several species of Germander
(Teucrium montanum, Scordiwm, &ec.), caused by Lactomelopus Tewerri, and on
the Rampion (Phytewma orbiculare), where they are produced by Cecidomyia

phytewmatis.
Closely allied to these bud-galls are those remarkable gall-structures which are
commonly known in Austria as “cuckoo-buds”. The cuckoo is supposed to be

concerned in their formation, just as it is in that of the frothy saliva-like masses
deposited by the Cicada on the Cuckoo-flower (Cardamine pratensis). The name
“euckoo-galls”” may be employed for the whole of this sub-group. They are char-
acterized by their pale whitish colour, soft spongy tissue, and especially by the fact
that they only involve the base of the shoot, while the upper end can continue its
growth unaltered. In this respect they may be compared to a Pine-apple fruit,
where the axis rises above the fleshy collective fruit (cf. p. 436) as a green leafy
tuft, which does not lose its growing power even with the ripening of the fruit.
The history of the development of cuckoo-galls is probably like that of covering
galls; and the main distinction lies in the fact that in the former the gall is pro-
duced not merely from a single organ or some part of it, but from a whole group of
adjoining plant-members. The best known and most widely distributed gall of this
group is produced by the pine-apple aphis Chermes abietis on the twigs of the Spruce
Fir (Abies eacelsa, see fig. 3627, p. 534). Early in the spring, before the foliage-leaves
have begun to unfold, the parthenogenetic females, the foundresses of the colony,
attach themselves each to the base of a young leaf and lay a mass of eggs at the
spot to which they have adhered. The larve, hatching, penetrate the surrounding
parts of the shoot with their beaks; the shoot swells, as do the bases of the
needles, and a growth, the Spruce gall or Pine-apple gall results. The gall somewhat
resembles a small Fir-cone about an inch long, with the surface divided into small
convex areas, each bearing a short needle-like projection in the middle; these are
the deformed needles, which, becoming swollen, touch each other on the outside of
the gall. They are separate inside, so that the gall contains a series of cavities or
chambers. In these chambers the larve live in numbers, either entering the
chambers during the growth of the gall or being inclosed by the swelling of the
surrounding needles—this point is not certainly determined. They remain in the
small cavities so formed and feed, cast their skins, and multiply there. In August
the gall begins to dry up, each of the small cavities opens by a slit in front of the
green needle-point surmounting the cushion (see fig. 3621, p. 584), and the winged
insects now leave the place in which they have passed the spring and summer.
Cuckoo-galls are met with almost as frequently on Stellate, viz. on various
species of Bedstraw (Galiwm Austriacum, boreale, wliginosum, &¢.) and Woodruff

BUD-GALLS. 545

(Asperula galioides, tinctoria, &.) as on Fir-trees. The infected parts of the shoot
remain stunted, and white spongy cushion-shaped growths, which are somewhat
grooved, arise at the bases of the leaves. Since the growing tissues of neighbouring
leaves touch one another the grooves or channels form small cavities in which live
the larves of the gall-producing gnats (Cecidomyia Galii and Asperulw). In the
common Bedstraw (Galiwm Mollugo) these spongy growths arise, not from the
bases of the leaves, but from the green cortex of the stem round the insertion of the
leaves and lateral branches. They rise up as cushions and lobes, and several join
together to form a sort of dome, under which the larve of the gall-gnat dwell. The
foliage-leaves are scarcely altered in form, and when lateral twigs arise from the
place they also are unchanged. It not infrequently happens that short lateral
axes terminated by flowers spring up quite unmodified above the spongy white
cuckoo-gall. Cuckoo-galls also occur on Crucifere, viz. on Barbarwa vulgaris,
Nasturtvwm palustre, sylvestre, and Sisymbriwm Sophia. They are produced by
Cecidomyia Sisymbrvi, and originate principally at the bases of the flower-stalks
half-way up the inflorescences. They look like spongy white bodies which surround
_ the pedicels like the brim of a hat. As the growths from neighbouring pedicels
meet together they roof over chambers which serve as habitations for the larve of
the gall-genats. Viewed from outside the galls appear like irregular white bodies
inserted in the inflorescence, which remind one of the fruit of the white Mulberry-
tree.

The term cluster-gall is reserved for that type of bud-gall in which the axis is
much restricted or stunted and covered with densely crowded leaf-structures; it
is in the chinks and recesses between the crowded leaves of these galls that the
insects concerned pass the whole or a portion of their lives. The animals which
cause the galls belong to very different classes. Gnats, leaf-fleas, leaf-lice, and mites
are the commonest varieties. The gnats only live in the galls during the egg and
larval stages, but the others pass their whole life there. They invariably settle
on the end of a shoot while it is still undeveloped in the bud. The axis of the
shoot remains more or less stunted in consequence of the influence the animals
exercise on it and its leaves undergo fundamental alterations. The blade or sheath
of the leaf is deepened and hollowed to afford sufficient space to the animals which
have established themselves between them, and as these parts of the leaves touch
one another recesses are formed not unlike those which are developed in fir-cones
for the growing seeds. The sheathing part of the leaf is often rather thickened,
and its succulent cells serve as food for the animals living in the gall; in other
instances the hollowed leaf-blades are thickly covered with hairs, and this coat
then has the same significance with regard to the insects as the felt of hairs on
isolated leaves already described. Very different forms of galls are produced
according as to whether the free ends of the leaves turn back or remain in contact,
and whether the axis from which the leaves spring is more or less contracted.
Sometimes they remind one of open rosettes, sometimes of closed balls, bunches and

tufts, sometimes of pig-tails and witches’ brooms.
Vou. I. 85

546 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

Clustered galls may be divided into two classes, those which develop in the
region of the flowers and those in the foliage region respectively. The most
noticeable and best known forms of the galls occurring in the foliage region on
rudimentary leafy shoots are the following:—First, those peculiar structures on
the tops of Willow twigs (Salia awrita, Caprea, grandifolia, &e.) which are popu-
larly termed “Rose Willows”. They are caused by the gall-gnat Cecidomyia
rosaria. The leaf-bud from which they arise keeps its axis quite short and
develops on it numerous green leaves arranged like the petals of a double rose.
The lowest leaves of the “rose” differ but slightly from the normal foliage of
the particular species of Willow. Usually there seems to be only a shortening
and broadening of the petiole and leaf-sheath, the green blade being almost un-
altered. In the upper inner leaves, however, the sheath-like part of the leaf is
much increased in size, and nearer the centre of the “rose” the leaves become
scale-like, The leaf-blade has entirely disappeared, and the end of the contracted
axis possesses only the remains of leaf-sheaths. It is worth noting that the
number of leaves in a Rose Willow is always greater than would be found on
an unaltered shoot of the same species. For example, if the number of leaves
on the one-year-old shoot of the Sallow (Salia Caprea) is 25, the number in
a “rose” on the same species would be at least twice as large. This can only
be explained by supposing that a “prolepsis” has occurred, 2.¢. that not only the
shoot laid down for the current year has developed, but also one originating from
a bud of this shoot, which, under normal conditions, would not have developed
until the following year. When autumn comes the rosette-shaped galls on the
Willow bushes show up conspicuously at a distance because the leaves forming
them do not fall off like the rest, but remain behind as brown dried structures
at the ends of the branches. They are also found associated with the catkins.
The rosette-shaped galls produced by the gall-gnat Cecidomyia crategi at the
tips of Hawthorn twigs (Crategus Oxyacantha and monogyna) also claim atten-
tion, They are full of bristles and resemble tiny birds’ nests. The stimulus of
the gnat larvae excites a deeper and more frequent segmentation in the leaves
and stipules. Narrower points and fringes which are much bent and which
resemble the antlers of reindeers replace the broad lobes. Also soft spines with
capitate ends rise up from the green cortex of the twigs and from the tissue of
the leaf-blade, especially above the vascular bundles, and 3-5 of them often fuse
together into cock’s-comb-like structures. These bristling rosettes on Hawthorn
branches also remain long after the time the ordinary foliage falls off.

In marked contrast to the rosette-like cluster-galls are others whose leaves
all fold together in a ball something like the leaves of a cabbage, the whole
gall having a button-like appearance. The outer leaves are round and hollowed
on their upper side, and they usually fold together like mussel-shells, The inner
leaves have a similar form, but they are much smaller and more concave, and
they have become succulent and paler in colour. The galls produced by Cect-
domyia genisticola on Genista tinctoria and those which Cecidomyia Veronice

BUD-GALLS. 547

gives rise to on Veronica chamedrys, and which gall-mites produce on the Wild
Thyme (Thymus Serpyllwm; see figs. 360+ and 360%, p. 531), form white buttons
on the ends of the shoots which show up conspicuously from the dark green
of the surrounding foliage. The white colour is due to the fact that the outer
leaves, which fold together like mussel-shells, are thickly covered on the outside
with white hairs. Cecidomyia Artemisie produces on the branches of Artemisia
campestris a closed cluster-gall which is cased in white wool like a shroud. On
the other hand, the large, button-shaped, closed cluster-galls which are produced
by Cecidomyia rosaria on Willows (Salia purpurea, &c.) and by a gall-mite on
the spikes of the Brome-grass (Bromus) are green and smooth, or at least they
have not more than the usual number of hairs.

On the shoots of the Yew (Taxus baccata), the Flax (Linum usitatissimum),
Euphorbia Cyparissias, the Moss Campion (Silene acaulis), and several Ericas
(Erica arborea, carnea, &c.) the influence of various gnats (Cecidomyia Taxi,
Euphorbie, Erice, scoparice, &c.) produces galls with linear erect leaves crowded
together into tufts. The base of the crowded leaves and the axis of the gall are
usually rather thickened, so that it looks as if the linear leaves were set on
a rounded button, and this is particularly marked in Huphorbia Cyparissias.
This division includes the gall formations occurring on Juniper twigs (Juniperus
communis), which are caused by the gall-gnat Lasioptera jwniperina. The
acicular leaves of the Juniper are arranged in whorls of three on normal shoots.
By reason of the influence of the gall-enat Hormomyia juniperina the whorls
at the top of the twig become so changed that the last but one represents a cup
bordered with three teeth in consequence of the broadening of the needles, while
the terminal whorl is metamorphosed into a dwelling surrounded by three short
leaflets. This gall closely resembles the cone of the Arbor Vite (Thuja occidentalis,
orientalis, and plicata) in form.

An insect, Livia Juncorum, produces galls on various Rushes (Juncus), espe-
cially Juncus alpinus and lamprocarpus, which look like knots or tassels. The
axis of the shoot is contracted, the sheathing portions of the leaves which cover
one another are much widened, and the colour is pale except where it is reddened
by exposure to the sun; their appearance is like the outer covering or top of
a tassel. The stunted green blades which spring from the sheathing portions
are thread-like and arranged as the loose strands of the tassel. Not infrequently
short lateral shoots arise in the axils of some of the leaves, and then the whole
structure looks like a bunch of tassels.

Closely allied to these cluster-galls on the stems of Rushes are such as re-
semble tufts and witches’ brooms, produced by mites on the branches of hairy
Willows, especially on the white Willow (Salix alba). Instead of the long leafy
Willow rod which would have emerged under ordinary circumstances from a
foliage-bud, a confused mass of twigs with short leaf-scales is developed which
at first seems a perfect mystery. By careful examination it is seen that the
axis of the shoot laid down in. the bud has remained stunted, and that lateral

548 ALTERATION OF FORM BY GALL-PRODUCING INSECTS,

shoots have developed from the axils of its leaves. These lateral shoots again
develop lateral axes in the axils of their leaves, and so on to the third, fourth, and
fifth degree. Thus, in the course of a month, shoots have unfolded, which, except
for the influence of the gall-mites, would not have followed one another for three,
four, five, or even six years, and therefore these galls afford us another instance
of what has been termed “prolepsis” or precocious development of structures
which would not yet arise. Of course all the axes of these shoots are dwarfed
and the leaves which clothe them are diminished in size. The shortening and
diminishing increase gradually, so that the axes and leaves of the fourth and
fifth degree are much smaller than those of the second and third. ‘The last
lateral shoots remain bud-like, and their small scaly leaves fold over one another
like the bracts in the involucre of a Composite. The “ witches’ brooms” which
are caused by gall-mites on Lilac (Syringa vulgaris) and Privet (Ligustrum vul-
gare) bushes are similar in nature to these closed galls on the Willows. Frequently
the metamorphosis of the leaves on the axes of the third, fourth, and fifth degree
includes those’ of the floral region, and such cases form to some extent a bond of
union between cluster-galls on foliage and on floral regions, respectively.

One of the most remarkable changes exhibited by the gall-structures just men-
tioned, viz. the abbreviation of the axis, is of course not to be noted in cluster-
galls in the floral region. The part of the axis which forms the floral receptacle
does not grow into an elongated shoot, but always remains short, and the floral-
leaves it bears stand close to one another, forming whorls in whose niches and
recesses numerous small animals can hide. But these animals effect other very
marked alterations by their stimulus. In some flowers, instead of the norma’
red, blue, white, or yellow petals, green leaflets appear which resemble foliage-
leaves in character, and then we say that the flowers have become “green” or
“leafy”. In other plants the stamens are transformed into petals, and the flowers
are said to be “double”. Finally, it may happen that the carpels which are usually
united together to form a syncarpous ovary stand on the receptacle as distinct
structures, and that to a certain extent their union has been dissolved. In these
cases we speak of “antholysis” (ef. p. 80). The influence of gall-mites also produces
metamorphosed flowers which may be both green and double, and in which the
pistil may have separated into its individual carpels.

The best flowers for observing these metamorphoses in all imaginable degrees
are the small-flowered species of the Chickweed genus (Cerastiwm macrocarpwum,
trwviale, &c.), several Caryophyllacese (Lychnis Viscaria, Saponaria officinalis,
&e.), Crucifere (Cardamine uliginosa, Camelina sativa, Lepidiwm Draba),
Gentians (Gentiana acaulis, rhetica), Speedwells (Veronica officinalis, saxatilis)
and Milfoils (Achillea Millefolium, nana). In Speedwells the petals come to
resemble leaves. The bunches, rosettes, and balls of small green leaves replacing
the flowers are set close together on the rachis of the inflorescence and form green
racemes and tufts, sometimes even small witches’ brooms. In Veronica sawatilis
the rachis of the raceme, the pedicels, and the bracts are covered with hairs, which

COMPOUND GALLS IN FLOWERS. 549

is not the case when the plants are free from the mites; the foliage-leaves in the
neighbourhood of the raceme are also lobed and deeply indented, which again is
not the case in uninfected plants of this species. In the capitula of the above-
named Milfoils the peripheral ray-florets as well as the central tubular ones become
leaf-like, and this gives rise to the most peculiar forms. <A capitulum is often sepa-
rated into several stalked sub-capitula, the flowers being metamorphosed into green
funnels with jagged mouths, and into small flat-lobed and toothed foliage-leaves,
whilst short, green, scale-like leaflets rise from the midribs of these leaves repre-
senting the metamorphosed stamens. A very remarkable “doubling” produced by
gall-gnats is to be observed in flowers of the Alpine Rose (Rhododendron ferru-
gimewm). The stamens and carpels are changed into red petals by their influence.
Since Rhododendron flowers have ten stamens and five carpels, there should be
only fifteen red leaflets in the centre of each, but as a matter of fact there are
double and treble as many, and there has been not merely a metamorphosis but
also a multiplication of the leaves. The flowers of some plants which belong to
the Valerians, especially of the Corn-salad (Valerianella carinata), of which a
small umbellate cyme is shown in fig. 358%, p. 523, are doubled by the influence of a
gall-mite, but without any multiplication of the petals. The doubling is restricted
to the transformation of the stamens into a whorl of petals. But we also have
another peculiar alteration. The petals become enlarged to more than fifty times
their normal size, and change into fleshy lobes which are fused with one another
into a disc. As all these lobes bend back, and become concave below, cavities
are formed under the flowers in which the gall-mites can dwell (see fig. 358%,
p. 528).

The axis of the inflorescence and the stalks of single flowers are often thickened
and fleshy in these cluster-galls, and they are also stunted and bent in the most
varied manner. If several neighbouring pedicels fuse together, structures like
cocks’-combs, or like a compressed and flattened branch, arise; to these the term
fasciation is applied. Sometimes when numerous pedicels arranged in the form of
umbels fuse together we have structures like coral-colonies, or irregular clumps
which are beset with green flowers usually much reduced in size. This is the case
in the fasciations of the Ash (Fraxinus excelsior and Ornus), which are caused by
a gall-mite (Phytoptus), and which occur so abundantly that it looks as if the tops
of the trees had been sown with them.

The enumeration, here, of various forms of galls commenced with the incon-
spicuous felt-galls on the under side of isolated foliage-leaves, and it ends with the
complex cluster-gall, in which hundreds of flower-stalks and leaves are frequently
concerned. Of course, only types of the individual groups which have been mentioned
in this long series could be instanced, and we cannot make any attempt to describe
all the gall-structures at present known, about 1600 in number. Whether the
extension of gall-researches in tropical regions will yield new forms which stand
outside the pale of the classification given it is difficult to say. Apparently this will
not be the case. Perhaps thousands of hitherto unknown galls might be added

550 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

to the list, but we should expect that they would fall under one or other of the
above-mentioned groups.

Gall-structures have a peculiar significance for the section of the Natural His-
tory of Plants which deals with the question of the origin of species, since they
show most distinctly how fundamental deviations from the original plan of con-
struction may occur in the adult condition of a portion of a plant.

We must be careful to remember always that the immense variety of structures
which we call galls would not have existed except for the effect produced on the
plants by mites, leaf-lice, gnats, wasps, &c. The foliage of Rhododendron would not
have been rolled up, but quite flat, if gall-mites had not been present; the branches
of Pistacia Lentiscus would have borne pinnate foliage with shining dark-green
leaflets and not fleshy-red pods if they had not been attacked by leaf-lice; the leaf-
bud of Quercus pubescens would have developed into a long leafy shoot instead of
a body like a medlar if the gall-wasp Cynips polycera had not provoked the
change; the foliage of Veronica saxatilis would not have been lobed like a hand,
but would have had a slightly sinuous margin; and the upper leaves of Thymus
would have been green, spoon-shaped, and smooth on the surface instead of circular
and covered with white hairs, had no gall-mites settled on them. The flowers of
Rhododendron ferruginewm, Lychnis Viscaria, Veronica, Cardamine, &c., would
not have “doubled”, and the stamens would not have changed into petals, if they
had not been under the influence of gall-mites.

Of course, the influence of the animals can only produce these effects on parts
of plants which are in an embryonic condition, Mature stems and leaves may
be eaten and destroyed by insects, but they can no longer be metamorphosed. But
the undifferentiated rudiments upon which the influence is effective are, so to speak,
formless, Leaves, stems, and fruits arise from tissue-masses having the form of
tubercles and cushions, and each tubercle or cushion originates from a few cells
which give no indication of what is to develop from them. Nevertheless, experi-
ence teaches us that the plan of construction for the plant-member proceeding from
these primitive forms is definitely laid down from the beginning for each species,
and the idea that the plan of construction is rooted in the specific constitution of
the protoplasm of the plant—i.e. in the cell or cells which form the primitive stage
or rudiment of the developing leaf, stem, &., is confirmed. If an alteration in
this plan of construction is produced by these animals, it can only be by some
alteration of the specific constitution of the protoplasm.

How the alteration is effected is just the puzzle which is at present occupying
the attention of naturalists. Once it was thought that the formation of galls was
the result of injuries caused in the growing tissue by the ovipositor or sucking
organ of insects, but recent investigations have not confirmed this view. The cells
actually injured by the insect in laying its eggs perish, and consequently lose the
power of metamorphosis or of producing modified daughter-cells. Cork, closing
over the wound, is always formed from the adjoining living tissue, but for a long

THE ORIGIN OF GALLS. 551

time no gall is produced. The eges deposited in the tissue, or attached to it, are
also incapable of directly inciting gall-formation. There is no marked alteration
in the neighbourhood until the grub or larva leaves the egg and exeretes a fluid
substance. Then growing cells of the most varied description are formed adjacent
to the larva, and these rapidly assume the peculiar forms which have just been
described. This, of course, applies also to cases where the larva has been hatched
from the egg at some distance from the spot and has had to seek out a tissue
suitable for its dwelling, as also to instances where adult gall-mites and leaf-lice
choose out a suitable place for the deposition of their eggs and then secrete a fluid
round them when they lay them. If the animal dies, the growth and renewal of
the tissue immediately ceases. The cells round the dead body turn brown and die,
so that we may conclude the formation of the gall to be due solely to the substance
excreted by living animals.

Those who investigate galls consider that it is chiefly the acrid “saliva”
excreted by the larve to liquefy their food which acts on the cell-tissue of the
dwelling they have selected, but there is no doubt that other excretions may also
take part. The chemical composition of this substance is unknown, but we shall
hardly be wrong if we include it in the group of nitrogenous compounds called
enzymes which were discussed at vol. i. p. 464. Enzymes have the power of
altering and decomposing substances, even through the cell-wall, and in this way
we can account very simply for a whole series of otherwise inexplicable phenomena
in the formation of galls. Moreover, urea or closely-allied nitrogenous compounds
may be excreted, so that there is nothing to be said against the view that some
of the substances diffuse into the interior of the plant-cells. It is at least certain
that the fluid substances excreted by the gall-producing animals, in whatever way
they influence the protoplasm in the plant-cells, do not kill it, but actually
stimulate it to an extraordinary new activity directly demonstrated by the pro-
duction of tissues with a definite external form.

Observation shows that these tissues are formed and fashioned differently
from what they would have been without the influence of this substance. It
follows, therefore, that the substances excreted by the animals have the capacity
of affecting in some way the specific constitution of the protoplasm which deter-
mines the species in the plant-cells influenced by them. It is specially interesting
to note in this connection that it not only is the protoplasm of the cells directly
acted on by the excretion which is stimulated to an altered form of constructive
activity, but that this stimulus is transmitted from cell to cell in ever-widening
circles. The spruce-fir aphis Chermes abietis attaches itself firmly by its beak to
the scale of a Fir bud, and can directly influence only a few cells of the young
shoot hidden in the bud. Nevertheless thousands of cells on this shoot soon begin
to assume an altered form, a proceeding which reminds us strongly of the action
of a ferment (cf, vol. i. p. 505), and also brings to our mind the influence exerted
by the spermatoplasm on the ovary. The spermatoplasm is only directly concerned
with a few cells in the ovule, but these propagate the influence on all sides to

552 ALTERATION OF FORM BY GALL-PRODUCING INSECTS.

the carpels and to the receptacle, and sometimes even to the flower-stalk. All these
parts would not have developed as they have done had it not been that the minute
quantity of spermatoplasm of a pollen-grain had united with a minute cell in the
ovule.

It will be convenient to consider here the already mentioned similarity between
galls and fruits. If the leaf-rudiments in the bud of a Pistacia shrub are not
affected by leaf-lice they develop into shining green pinnate foliage-leaves; but
if the protoplasm in some of the cells has been altered by the excretions of
Pemphigus cornicularius this same rudiment will assume the form of a carpel,
and become fashioned into a hollow body deceptively like a pod. The fact that
the Pistacia shrub bears plum-fruits and not pods makes it still more remarkable,
for the structure arising from the effect of the animal’s excretion, when mature,
is not like the fruit of the Pistacia, as we should naturally have expected, but like
that of a completely different plant species, viz. the Carob (Ceratonia Siliqua).
The same is true of the metamorphosis caused by the excretion of a gall-gnat
(Lasioptera juniperina) on the uppermost leaves of the Juniper (Juniperus
communis) which assume a form very like the fruit of the Arbor Vite (Thwa),
and many other instances might be mentioned in which galls are produced in
certain species of plants by animal excretions, looking outwardly very like the pods,
capsules, nuts, drupes, and berries of other species. This resemblance to certain
fruits is rendered the more pronounced by the development upon the galls of pig-
ments, wax-like excretions, and hairy coverings, but of course they contain no seeds
in their interior—only the larve of the animals whose excretions produce the
changes of form. The wonderful thing is that the metamorphosis of the growing
tissue into a fruit-like body is always of the greatest advantage to the animal
which has settled in it, since the tissue serves not only for dwelling and food but
also for protection against unfavourable weather and against the attack of foes.

It is also a fact of great importance that different animals produce differently
shaped galls on the same plant. The Bedeguars produced by Rhodites Rose, the
pea-like galls produced by Rhodites eglanterie, and the clustered protuberances
produced by Rhodites spinosissime may all occur side by side on the same rose-
leaf (see figs. 361+%* p. 533). On the same elm-leaf Schizonewra Ulmi produces a
wrinkled gall, Tetranewra Ulmi a pocket-gall, and Tetraneura alba a covering gall
(see figs. 3614°% p. 533). The spherical gall of Nematus gallarwm and the bladder-
like gall of Nematus vesicator occur close together on the foliage of the Purple
Willow (see figs. 361’ and 3618), and one sees Oak-leaves on which the small
spangle-galls of four different gall-wasps, viz. Newroterus lanuginosus, numis-
matis, fumipennis, and Spathegaster tricolor are all present together (see
figs. 3644 1218,14 5.541). It has been shown that some Oaks, for example, Quercus
pedunculata, may bear as many as 20-30 different forms of gall produced by as
many kinds of gall-wasps. The characteristic shape, colour, and hair-covering of
these forms of gall is so constant: that we can state with certainty what gall-wasps
have given rise to them. These facts force us to the conclusion that the fluids

GENERAL CONSIDERATIONS, 553

excreted by different gall-producing insects are specifically distinct. It is only in
this way that we can account for the fact that the same vegetable protoplasm is
incited in one case to produce a fleshy covering gall, in another a hollow pocket, and
in a third a closed gall-apple as dwellings for the particular insects concerned.

It should also be mentioned that the same species of insect produces very similar
but slightly different galls on different plants. For example, the gall produced
by Nematus pedwneuli on the lower side of the white-haired leaves of Salix
vcana is covered with a white felt of hairs, that which the same gall-gnat pro-
duces on the smooth leaves of Salia purpwrea is smooth; the gall produced by
Rhodites Rose on the light green leaves of Rosa canina is pale yellow and some-
what reddened on that side turned towards the sun; that on the violet leaves of
Rosa rubrifolia produced by the same insect-species is dark violet, &. These
distinctions, though only insignificant, show how certain external characteristics
founded in the specific constitution of the protoplasm of different plant-species find
expression even in the gall-structures.

These facts confirm the view that the fluids excreted by different species of
insects, as well as the protoplasm of each plant species, have a peculiar composition.
It is then quite obvious that the alteration which the protoplasm of a species of
plant undergoes under the influence of a specific fluid will be subject to definite
laws. The protoplasm of the particular plant-cell receives by reason of the
alteration, as it were, a new definite constitution with tendencies not the same
as before; but since this constitution determines the outer form of the tissue
derived from these cells, the tissue itself will become shaped into a particular specific
form. These conclusions are of importance with respect to the question of the
origin of new species, inasmuch as they throw some light on the processes which
lead to the origin of new forms. We can now say that the alteration in the form
of a plant only occurs if the constitution of the protoplasm which forms the starting-
point of the plant is itself first altered.

The structures known as galls have not the power of maintaining and multi-
plying themselves, but when their task is ended they perish. In other words, the
progeny arising from the seeds of a plant beset with galls exhibits none of the
alterations shown by the members or shoots of the parent plant. If, for example,
an Oak which is covered with galls is propagated by seeds, the offspring show
no trace of the structural alterations exhibited by the branches, foliage, or flowers
of the mother-plant. The only change which is perhaps sometimes retained
in the offspring is the metamorphosis of the stamens into petals, which has long
been known as doubling, and perhaps also the formation of fasciations, &. in the
floral region, as in Cabbages (where it is known as a Cauliflower). Few attempts
have yet been made to investigate this matter. My own knowledge of the subject
is restricted to some observations made on the Speedwell Veronica officinalis.
Plants of Veronica officinalis which in consequence of the settlement of gall-mites
on them produced double flowers in 1877 in the garden of my country house were
planted close beside others free from gall-mites and with normal flowers. In the

554 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

following year the gall-mites settled on the latter also, and the greater part of their
flowers then became double. The same result was obtained after living gall-mites
were transferred by me to isolated plants of Veronica officinalis with single
flowers. These in the following year also bore some double flowers. Fruits with
ripe seeds were only produced from the flowers which had remained single amongst
the double ones; and the plants which grew up from these seeds always bore single
flowers only. The gall-mites disappeared for some unascertained reason—probably
they died in the winter. Veronica officinalis has only two stamens in each flower,
and in the double flowers both these and the two carpels are changed into petals
so that of course we could not expect fruit and seeds from them. It would not
be impossible, however, that flowers of other plant families which are provided
with a large number of stamens might behave differently. It might happen,
for example, that only some of the stamens would be changed into petals by the
gall-mites, and that the carpels would remain capable of fertilization. If on such
plants fruits and seeds capable of germination should ripen, the latter might
perhaps produce plants with completely and half double flowers. This would be
explained by supposing that the alteration undergone by the protoplasm of the cells
in the outer part of the flower had extended to the inner, especially to the ovules
and seeds, and further to the plants proceeding from these seeds. I would there-
fore not undertake to state that the Stocks (Matthiola annua and incana), the
Wallflower (Chetranthus Cheiri), the Pinks (Dianthus Caryophyllus, plimarius,
&c.), the Poppies (Papaver Rheas and somniferum), various Ranunculacee
(Delphiniwm, Peonia, Ranunculus), and many other plants which have long been
cultivated in gardens with semi-double flowers, and which produce such flowers
when propagated by seeds, had not gained this characteristic in the first place
by the influence of gall-mites. It is less probable, though not beyond the range
of possibility, that by the grafting of Hawthorn branches whose uppermost leaves
have been deeply segmented by the influence of the gall-gnat Cecidomyia Crategi,
a Hawthorn bush might be produced which would exhibit these deep segmentations
and slits on all its foliage. However, these last remarks are the merest suppositions;
at present we have not the data on which to base any definite conclusions.

THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

The aim of agriculturalists has always been so to cultivate their land as-to rear
plants likely to grow luxuriantly, to bear good fruit, and thus to afford an abun-
dant harvest in return for their pains. Gardeners similarly have made it their
endeavour to produce from wild plants races whose flowers are superior to those
of the ancestral stock in form, colour, and scent; and the results of their labours
are the delight and admiration of all lovers of beauty. In both cases the idea has
been to perfect and “ennoble”, and the means adopted have been successful to a
degree calculated to amaze anyone who studies the history of cultivated plants with
attention. The methods which led to these results have not always been deliber-

LARGE PRODUCTION OF NEW GARDEN FORMS. 555:

ately adopted, nor have they depended on scientific researches. On the contrary,
chance observations made by growers in the course of their dealings with vegetable
life as it occurs in nature have been the means of suggesting the first unaided
attempts to make crops more productive, fruits and vegetables more palatable, and
flowering-plants more pleasing to the eye.

The most important method adopted has been the artificial crossing of the
species which are brought under cultivation. When we consider that, from time
immemorial, Chinese and Japanese gardeners have produced Asters, Chrysanthe-
mums, Camellias, Pinks, Peonies, and Roses, of which the majority are the results of
crossing, we may assume with certainty that the practice of dusting flowers of one
species with the pollen of another species first came into use in those countries. It
is true that in Europe the contrivance was known to rose-growers at the time of
the Roman Empire, but it was not employed on an extensive scale till the seven-
teenth century, when the fashion for breeding Tulips and Auriculas became the
rage. The gardeners of that day still made a great secret of their mode of pro-
cedure, and it was not till the latter half of the eighteenth century that the
production of new forms of plants by the aid of artificial crossing was carried on
at all generally. For some decades the rearing of these new forms, which are
called hybrids, has been one of the most important parts of a gardener’s duties, and
we shall not exaggerate if we put the number of hybrids hitherto produced in
gardens in the course of the nineteenth century at 10,000. Many hybrids which
were great favourites only a short time ago have disappeared from our gardens
and have been replaced by others. As in so many other matters, the fashion
changes; new forms are in constant request, and horticulturists endeavour to meet
the demand by introducing wild plants from the most various regions and crossing
them with those already under cultivation. It is now no longer uncommon for
gardeners, in advertising some plant which has been brought from distant parts, to
recommend it to the trade, not on the ground of its own beauty, but because it
possesses flowers of an exceptional colour or leaves of a peculiar cut, and will there-
fore, in all probability, if crossed with other species, yield handsome new hybrids.
Rose-growers always welcome the discovery of any instance of variation in the Wild
‘Rose as an important event, because, by crossing this Rose with others, they are
able to produce a large number of new forms, and there is always the chance that
one or other of them may find favour with the public. On an average, 60 newly-
bred Roses come into the market yearly; in the year 1889 the number even
amounted to 115! A Rose cultivator at Meidling, near Vienna, grows in his garden
nearly 4200 different kinds of Rose, and yet he is still far from possessing all the
forms which have been produced in recent times (chiefly by French growers) by
crossing one with another. According to his estimate, the number of Tea and
Indian Roses alone is nearly 1400, and the total number of all the different Roses
which the trade has produced up to the present day amounts to 6400.

The plant-forms which are called into existence by the operation of crossing are,
in the case of Roses, reproduced largely by means of brood-bodies (cuttings and

556 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

layers) as well as by budding and grafting (see vol. i. p. 213); but the first origin
of the new forms is always to be traced to crossing. This statement applies also to
many other plants of which gardeners have taken possession, and especially to cases
where propagation by seed requires more time and trouble than multiplication of
brood-bodies. The kinds of Tulip, Gladiolus, and Lily produced by crossing are
propagated most easily by means of bulbs, and the tuberous Begonias, Dahlias, and
Gesneracee by tubers, whilst Pinks, Pelargoniums, Cactuses, and many others are
most rapidly reproduced by cuttings. Moreover, these methods ensure the preser-
vation of the peculiarities of the new forms unchanged, and such perpetuation of
characteristics would be much more difficult to achieve if the plants were propa-
gated by means of seeds. On the other hand, a number of new forms which have
originated as the results of crosses effected in gardens, such as those of Petunia,
Portulaca, and Viola, are reproduced with less trouble and greater rapidity by
seeds, and that method is in such cases preferred to the cultivation of brood-bodies.

The statement that new forms of plants are bred originally in gardens by any
other method than that of crossing is incorrect; it is sometimes made in ignorance,
but sometimes also with the intention of deceiving. In former times gardeners
believed that, in order to produce new forms, it was sufficient to plant different
species in close proximity to one another. The idea was that if the seeds of such
plants were taken and sown in good soil, there would always be found amongst the
seedlings a few forms differing from the parent; these were to be selected for
especial care in cultivation, and were to be treated as starting-points of new forms.
The gardeners who acted on this assumption had not, it is true, themselves crossed
the flowers; and if this was all they meant, there was no falsehood in the state-
ment. The operation of crossing was, however, performed without their knowledge
by hive- and humble-bees and other insects, and the planting together of the
different species was only of advantage inasmuch as it facilitated the conveyance
of pollen from one species to the stigmas of another. A celebrated grower of the
old school once assured me, in all seriousness, that he did not himself cross the
plants he reared, but that he had repeatedly observed that early in the morning,
soon after a flower opened, it put forth infinitesimally fine threads which radiated
in all directions and reached across to the flowers of other plants, forming in a short
time a web like that of a spider! I would not have mentioned this statement were
it not for the importance of pointing out the unreliable character of so many of the
statements made by gardeners, especially in the past; and I repeat that the person
responsible for the above communication is a well-known and much-esteemed horti-
culturalist. Gross inventions such as the above would, of course, be at once seen
through and rejected by any thoughtful man; nevertheless, in some instances,
reports of growers, likewise untrue or inaccurate, but not bearing the stamp of
improbability so plainly upon the face of them, have been credited and have even
found their way into books, particularly into those whose authors have omitted to
confirm the reports by watching the garden-experiments from beginning to end
themselves. The statements are then not infrequently quoted as “results obtained

THE PRODUCTION OF HYBRIDS. 557

by trustworthy experiments made by gardeners” and relied upon for the foundation
of “laws based upon facts”; theories are then built up upon them, and are copied
from one book to another. It becomes very difficult afterwards to get rid of such
propositions, especially if they afford support to the hypotheses of distinguished
savants,

An instructive example of the kind of thing referred to is afforded by the
following statement which for a long time obtained currency in works on Botany:
“Hybrids resulting from the crossing of two species exhibit two forms, in each
case, according as the pollen employed in generating them belongs to the one or
to the other species.” There are, of course, two ways in which a pair of species,
which may be represented by the letters A and B, may be crossed. In one case the
pollen from A is transferred to the stigma in B, whilst in the other case the pollen
is taken from B and transferred to the stigma in A. Now, it has been asserted
that it is possible to determine from the form of the hybrid which of the two.
parent-species supplied the pollen. The hybrid is said to resemble that parent more
closely from which the pollen was derived so far as its flowers are concerned, but
to show greater affinity to the fertilized stock in respect of its foliage. This is,
however, absolutely untrue. All careful experiments, made without prejudice have
pointed to the conclusion that it makes no difference to the forms, either of the
leaves or of the flowers, whether the pollen has been taken from the one parent-species.
or from the other. Besides this, in most instances the approximation of the hybrid-
form to one or the other stock affects all parts of the hybrid plant in an equal
degree, and not the flowers or the foliage only. In the rare cases where a hybrid
has flowers more like those of one parent and leaves more like those of the other,
it is just as likely for one stock as the other to have yielded the pollen used for the
cross.

But it would be a thankless task to attempt to correct all the hasty, careless,
and erroneous statements, past and present, and it will probably be of greater
utility to give a general survey of what has been ascertained concerning the form
and temperament of hybrids by impartial observers who have taken into account
all the concurrent circumstances, and have allowed for the sources of error inci-
dental to the experiments.

The formation of a hybrid plant presupposes two stock-plants as parents which
have different properties and characters. A cross must take place between the two
—that is to say, the stigma of the one must be dusted with pollen from the other;
the pollen must put forth pollen-tubes and an effectual union between spermato-
plasm and ooplasm must be effected. For the sake of brevity, the plant from which
the pollen, and therefore also the spermatoplasm, is derived is called the paternal
stock or father-plant, and that which has its stigma dusted and its ooplasm ferti-
lized is called the maternal stock or mother-plant. As a plant’s external marks and
characteristics, which are perceptible to our senses, are an expression of its internal
organization and of the specific constitution of its protoplasm, it may be assumed
that the plant-individual which owes its existence to the union of two protoplasts:

558 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING,

of different constitutions possesses marks and attributes, some of which are charac-
teristic of the father and others of the mother. As a matter of fact, the individuals
which growers call by the various names of hybrids, mongrels, and bastards answer
to this supposition. Some of their attributes and external characters are derived
from the paternal, some from the maternal stock. If the relative admixture of the
two stocks were to be determined in the case of a hybrid by summing up the
characteristics transmitted from each source, the share of each parent would in
many cases be found to be a half. In such a case it is usual to say that the hybrid
is a mean between its parents. Examples are afforded by Geum hybridum, which
originates from crossing Gewm montanum and G. rivale, Hreraciwm stoloniflorum,
derived from Hieracium aurantiacum and H. piloselleforme, and Nuphar inter-
medium, a cross between Nuphar luteum and N. pumilum. But it also happens
sometimes that the proportion of characters inherited by a hybrid from one of the
parent-stocks amounts to about two-thirds, leaving only one-third as the propor-
tion inherited from the other, and in that case the hybrid is said to exhibit an
approximation to one of the parent-species. The Saxifrage hybrids are very
instructive examples of this class. The stigmas in a flower of Sawifraga aizoides
were dusted with the pollen of S. cesia. Fertilization was successfully effected, .
and a capsule containing fertile seeds came to maturity. The plants reared from
these seeds resembled in some cases the intermediate form described by Botanists
- under the name of Saaifraga patens; others approximated more closely to the
paternal stock, and a third group to the maternal stock. A similar result was
obtained by crossing a flower of Sawxifraga aizoides with the pollen of S. mutata.
From seeds of the same capsule were produced two different kinds of hybrid,
of which one was intermediate between the parents (Saxifraga Hausmann),
whilst the other (Saaifraga inclinata) approximated more closely to S. mutata.
These experiments point to the conclusion that the share which each parent
has in the form of a hybrid depends upon the quantity of its spermatoplasm
or ooplasm, as the case may be, used in the production of the seedling relatively
to the quantity derived from the other parent; and in the case of hybrids issuing
from the same fruit we are forced to suppose that the variability of the degree in
which a particular form is inherited is caused by the existence of quantitative
differences between the several spermatoplasmic and ooplasmic nuclei (or cells)
which coalesce in pairs in the interior of the same ovary.

Important evidence in support of this supposition is derived from experiments
made in connection with the crossing of various composites of the Thistle genus
(Cirsiwm). In these plants each ovary contains a single ovule only, and therefore
each fruit can only produce a single individual. On the other hand, each capitulum
is composed of a large number of florets, and when a head is in full bloom nearly a
hundred mature stigmas project from it in close proximity to one another. If pollen
from another species is transferred by means of a paint-brush on to these stigmas,
wholesale crossing, so to speak, ensues; and it may be confidently expected that a
proportion of these simultaneous crosses will be effectual, The harvest of fruit

DIVERSITY OF HYBRIDS FROM SAME PARENTS. 559

from the capitula selected for the experiment was not, it is true, very plentiful, but
some fruits invariably came to maturity. If these one-seeded fruits, all of which
have originated at the same time and under similar conditions, are sown, the indi-
viduals produced from them are but seldom like one another. The attributes and
external marks of the paternal and maternal stocks respectively are in some repre-
sented in the proportion of about 2:1, in others in the proportion of 1:2, and ina
third class in practically equal proportions; cases are even known where four, five,
or more distinct forms of hybrid have developed from the fruits of a single
capitulum. I found the most striking differences amongst the hybrids obtained by
crossing a capitulum of Cirsiwm oleracewm with the pollen from a capitulum of
Cirsium heterophyllum. Those produced by crossing a head of Cirsiwm Pannoni-
cum with pollen from a head of Cirsiwm Erisithales were scarcely less conspicuously
diverse. As it must be presumed that the spermatoplasm and ooplasm—or rather
the spermatoplasmic and ooplasmic nuclei—which have been formed in the adjacent
florets of a capitulum are alike in composition and ultimate structure, the variety
of the hybrids springing from such florets must depend solely on the relation
between the masses of ooplasm and spermatoplasm respectively which coalesce in a
flower, and the ratio between these masses must be in the one case 1:2, in a second
1:1, and in a third 2:1. Of course these ratios give but an approximate measure
of the degree in which each parent has participated in the generation of the inter-
mediate forms. Where five kinds of intermediate forms occur the series would be
approximately represented by the ratios 1:4, 2:38, 1:1, 3:2, and 4:1. The first
time flowers of a head of Cirsium Hrisithales were crossed with pollen from
Cirsium palustre they produced two different forms of hybrid, one of which
approximated to the paternal, the other to the maternal stock; but no form exactly
midway between the two parent-stocks was obtained. A second trial of the same
experiment resulted in the production of a single form which did occupy this inter-
mediate position. These observations show that there is no definite law governing
the form of hybrids; one might even say that irregularity is here the rule. On one
‘ oceasion all the individuals which are the result of a cross between two species are
alike, on another occasion they constitute more or less numerous links in a chain of
intermediate forms.

Hybrids which do not stand midway between the parent-species but approximate
to one or other of them are called goneoclinic (yores=parent, «vw=I lean). That
such hybrids may arise from a first cross is established beyond question by the
experiments above recorded; but there is also another process whereby they are
produced, and that is the crossing of a hybrid with one of its parent-stocks. These
crosses are effected in great numbers, and all observers agree that in general the
results are better in such cases than where two species are crossed; that is to say, if
a hybrid’s stigmas are dusted with the pollen of one of the parent-species a larger
number of fertile seeds may be looked for than if the plants crossed were of distinct
species. The individuals resulting from the cross of a hybrid with one of the parent-
stocks also occupy, as might be expected, a position as regards marks and attributes

560 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

intermediate between their progenitors; here again, however, forms are not always
alike, and sometimes several intermediate forms make their appearance. If the
hybrid derived from Cirsiwm Erisithales and C. Pannonicum, which inherits equally
from both parents, be crossed with pollen from Cirsium Erisithales, the resulting
individuals have a stronger resemblance to the latter species and are instances of
goneoclinic hybrids. But when Cirsium Hrisithales and C. Pannonicum are
crossed for a first time hybrids are also produced which are not exactly midway
between the parents but are more like C. Hrisithales. These naturally resemble
the goneoclinic hybrid derived from crossing the offspring of C. Erisithales and C.
Pannonicum with C. Erisithales, and if one were not in a position to follow the
history of the origin of the hybrid in question its characteristics alone would not
furnish sufficient data for a judgment as to the mode of production of the goneo-
clinic hybrid.

Hybrids which are the offspring indirectly of three different species are called
ternary hybrids. The word “indirectly” must be specially emphasized here, lest
the reader should fall into the error of supposing it to be possible that pollen-tubes
from two or more species should simultaneously fertilize a single ovule. Such an
occurrence never happens, not even if a mixture of pollen belonging to two or more
different species be placed upon the stigma of a particular flower. On the other
hand, it has been ascertained by numerous experiments that if the hybrid-offspring
of two species is crossed with the pollen of a third species, or vice versd, another
hybrid is produced. Thus, for instance, if the hybrid of Linaria genistifolia and
L. purpurea is crossed with the pollen of L. striata the result is a ternary hybrid.
In one experiment the stigmas in a capitulum of Cirsium Linkianwm (the hybrid
offspring of C. EHrisithales and C. Pannonicum) were dusted with pollen taken
from C. palustre. A considerable number of fruits ripened, and the hybrids which
arose from them were ternary hybrids, exhibiting marks and characteristics of
C. Erisithales, C. Pannonicum, and C. palustre respectively. These hybrids, more-
over, were not all alike; some of them bore striking resemblance to Cirsiwm aquilo-
nare, the hybrid produced by crossing C. palustre and C. Pannonicum, and exhibited
very few of the peculiarities of C. Hrisithales, whilst other individuals were ex-
tremely like Cirstwm ochroleucwm, the hybrid obtained by crossing C. Erisithales
and C. palustre, and only showed slight indications of its relation to O. Pannon-
cwm. Growers of garden-flowers have achieved great success in producing orna-
mental ternary hybrids in a number of genera (Achimenes, Begonia, Dianthus,
Gladiolus, &¢.). Ternary hybrids of various Willows are also met with in
gardens; one of these is obtained by crossing Saliw Cremsensis, a hybrid of Salix
Caprea and 8. daphnoides, with 8. viminalis, another by crossing Salia Wichure:
(the hybrid-product of S. incana and S. purpurea) with S. cinerea, and so forth.
Willows have been also used for the prosecution of still further experiments. The
crossing of two hybrids of different parentage on both sides resulted in the genesis of
hybrids combining four species of Willow. Indeed, six different species of Willow
have on one occasion been combined by successive crossing— Wichura having

COMBINATION OF PARENT-CHARACTERS. 561

succeeded in producing in Breslau a compound hybrid in which were united Sali«
Caprea, 8S. daphnoides, 8. Lapponum, S. purpurea, 8. Silesiaca, and S. viminalis.

It need hardly be said that the characteristics of the six ancestral species in such
a case as that of the last-mentioned hybrid are not easily identified. Even where
a hybrid is the offspring of a single cross between two species it is not always easy
to determine its origin from its external appearance, and in the absence of any
knowledge of the history of its production. The characteristics of the parent-stocks
are not combined in all hybrids according to a single definite rule. Sometimes the
combination seems to amount to a complete fusion, so that the form produced might
be compared to an alloy of two metals. Very often a new form is generated which
combines in a definite geometrical ratio the characteristics of the parents in respect
of the position and direction as well as the shape and size of its separate parts. In
that case there is said to be a union of the parental characters. The structural
characters of both stocks are represented unmodified, but are so closely bound
together as to suggest a composite crystal founded upon two different crystalline
forms. Just as in definite combinations of crystals the faces of one component form
are dominant, and determine the general aspect in one case and those of the other
component form in another case, so in many hybrid plants sometimes the attributes
of the one parent, sometimes those of the other, are most conspicuously reproduced.
Other hybrids again are analogous to combinations in which both crystalline forms.
are equally represented. Again, in addition to the above classes of hybrids
wherein the parental characters are either completely merged together or intimately
united there are many. cases where those characteristics are present almost un-
changed, and subsist side by side like the particles of a rock. The most common
case of this mixture or juxtaposition of properties occurs where the hybrid displays.
hairs, glands, or prickles of two forms interspersed together, one of which is identical
with the form of the structure in question exhibited by the maternal stock, whilst
the other has been inherited unchanged from the paternal stock. Or, one part of
the hybrid’s flower may be coloured like one parent and another like the other
parent. Hybrids are also known in which the foliage is almost indistinguishable
from that of one parental stock whilst the flowers are like those of the other, so that
at first sight a hybrid of the kind looks as if it were a plant of the former species
with flowers of the second species affixed to it for a joke. On closer inspection some
slight differences may be perceived between the leaves and flowers of the hybrid and
those of the parent species respectively, but this does not alter the fact that hybrids
exist whose leaves resemble far more closely those of one parent, whilst their
flowers are more like those of the other. Probably it was the occurrence of such
a hybrid which suggested the proposition referred to on p. 557 that in the product
of a cross between two species the flowers reveal the paternal and the foliage the
maternal stock. But this statement is incorrect, as was said before, for some
hybrids approximate to the maternal stock in respect of their flowers, and to the
paternal stock in respect of their leaves.

Of the three ways in which the parental characters may be combined in a
Vor, I. 86

562 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

hybrid—i.e. by fusion, by union, or by mixture—one alone sometimes prevails in all
the parts; but usually, on the contrary, there is an incalculable degree of variation
in this connection. There are, for example, Rose hybrids in which the outline of
the leaves exhibits a union, the colour of the flowers a fusion, and the hairs a mix-
ture of the corresponding characters in the parents.

A brief account will now be given of a few examples to illustrate the manner in
which the combination of parental characters in a hybrid is manifested throughout
the structure of the plant and particularly in the forms of the stems, leaves, and
flowers, and in those of thorns, bristles, hairs, and other epidermal appendages. The
species of Willow known as Salix Caprea grows in the form of a little tree, with
thick, straight, erect branches, each of which bears about 25 leaves; Salix repens,
on the other hand, is a low shrub with a procumbent stem and slender, rod-like
branches ascending in curves from it, and each bearing about 40 leaves. The
hybrid of these two is a small tree with a bent stem and ascending branches, which
in length, thickness, curvature, and direction are intermediate between the Salia
Caprea and Salia repens, and which are furnished with some 30 leaves apiece.
Again, the foliage-leaves of Prunella vulgaris have their margins entire, whilst those
of P. laciniata are deeply cut, and their hybrid Prunella intermedia has lobed
leaves. The leaves of Potentilla sterilis (or P. Fragariastrum) possess three
leaflets, each leafiet being furnished on either side with from four to five serrate
indentations. The leaves of Potentilla micrantha likewise possess three leaflets,
but each leaflet has from seven to ten serrate teeth on each side. In the hybrid
of these two species the leaflets have from six to eight indentations on each side.
The shape of the leaf is, as is well known, intimately connected with the course,
ramification, and disposition of the bundles called nerves. Now, if the net-work of
strands in the leaves of the parent-species is compared with that in the leaves of
the hybrid, it is astonishing to find how the union of the two systems may be
traced in the minutest details. No group of plants lends itself better to this sort
of investigation than the Willows. Even if a single leaf of the hybrid offspring
of two species of Willow is submitted for inspection, it is possible in most cases to
determine, from the number and distribution of the nerves, the identities of both
its parents. Salia purpurea produces one hybrid when crossed with Salia grandi-
Jolia, and a second when crossed with Salix Caprea. Salia grandifolia has twice
as many lateral nerves in each leaf as Salia Caprea, and this difference is repro-
duced in the corresponding hybrids, whose leaves in all other respects resemble one
another closely.

The involueral leaves of Composites are well known to be extremely diverse in
shape, and systematic Botanists have always attributed great importance in the
discrimination of species to the size, shape, and margination of these leaves and to
the peculiar appendages at their apices. Now, the hybrids of Composites not
infrequently have involucral leaves which differ widely from the forms character-
istic of the parent-stocks. Thus, for instance, each leaf of the involucre in a
capitulum of Centaurea rupestris terminates in a long yellow prickle, whilst the

COMBINATION OF PARENT-CHARACTERS, 563

corresponding structure in Centawrea Scabiosa is bordered by a broad, membranous,
fringe-like edge of a dark-brown colour. In Centawrea sordida (Grafiana),
the hybrid offspring of these two species, each involucral leaf is edged with a
narrow, light-brown membranous and fringed border, and terminates in a short
yellowish prickle. A very instructive example of the union of parental characters
affecting all the different parts of the floral region is afforded also by the Labiate
Marrubiwm remotum, which is produced by crossing Marrubiwm peregrinum and
M. vulgare. The small tuft-like inflorescences in the leaf-axils of Marrubiwm
peregrinum include from 10 to 18 flowers, those of M. vulgare from 4 to 5, and
those of the hybrid M. remotwm from 5 to 10. The calyx of M. peregrinum is
grey and covered with felted hairs, and its margin is provided with five large
subulate teeth which terminate in straight points. The calyx of M. vulgare is
green and sparsely clothed with hairs, and its edge has ten small teeth which
terminate in stiff reflexed points like hooks. Five of these teeth are rather longer
than the rest. The calyx of M. remotuwm is greyish-green and clothed with a
loose felt; its edge is furnished with five big subulate teeth which terminate in
stiff out-curved points, and have from two to five very small teeth interspersed
between them. The three lobes of the under-lip of the corolla are almost of equal
length in Marrubium peregrinum, whilst in M. vulgare the middle lobe is three
times as long as the two lateral lobes. In the hybrid Marrubiwm remotum the
middle lobe of the lower lip is half as long again as the lateral lobes. An excellent
example is also afforded by Dianthus Enipontanus, a hybrid Pink resulting from
across between Dianthus alpinus and D. superbus. In D. alpinus the bract-like
scales at the base of the calyx are almost as long as the tube of the calyx itself,
whilst in D. superbus their relative length is only a quarter or a third; in the
hybrid D. Enipontanus these bracts are half as long as the tube. The petals of
D. alpvnus have broad lamine beset at the margin with short triangular teeth,
those of D. swperbus have their lamine slit up into a number of narrow strips, and
those of D. Enipontanus have deeply-incised laminz, the margins being divided
into linear segments. The dimensions of the various parts of the flower in a hybrid
also exhibit in most cases a combination of the corresponding parental character-
istics. Thus, for instance, the perianth of the Orchid Gymnadenia conopsea has a
long spur—that is to say, the segment of the perianth known as the labellum is
produced backwards into a saccate protuberance supposed to resemble a spur, and
this portion of the petal in Gymnadenia conopsea is 15 mm. in length. In Nigri-
tella nigra, on the other hand, the spur is very short, measuring about 2mm. The
hybrid of these two Orchids, Nigritella suaveolens, has a spur varying from 5 to
7mm. in length. In Willow hybrids the number of stamens in each flower of the
hybrid is invariably between the corresponding numbers in the two parent-
species. For example, the number of stamens in a flower of Salix alba is 2,in
Salic pentandra 5-12, and in their hybrid Salia Ehrhartiana 3-4.

The cellular structures produced from the epidermis of the stem and leaves
which are differentiated as hairs, bristles, scales, glands, &c., and are classed together

564 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

under the name of investments (indumentum), are very constant characters in most
species of plants. The occurrence of stellate hairs, in particular, is looked upon by
systematic Botanists as an important point in assisting them to distinguish between
similar species, and so also is the presence of glandular hairs composed of simple
rows of eells, and terminating in globular bladders full of ethereal oils. Hybrids
exhibit the most varied combinations of the indumenta of their parents. In the
majority of cases the characteristics of the two stocks in this respect are mixed, but
less frequently are they united, and in the latter case the shape, size, and number of
hairs, bristles, scales, and glands are intermediate between those of the same appen-
dages in the two parent-species. The Lungwort genus (Pulmonaria), which has a
special tendency to hybridization, includes only a few species, but each one may be
recognized by the nature of its indumentum. Thus, Pulmonaria officinalis is dis-
tinguished by the thousands of short unicellular prickly hairs, scarcely perceptible
to the naked eye, which are interspersed amongst the long scattered bristles on the
upper surfaces of the leaves. In Pulmonaria angustifolia the leaves are destitute
of these minute prickles, but bear on their upper surface a more abundant quantity
of straight appressed bristles of equal length. The leaves of the hybrid derived
from the two preceding species, viz. Pulmonaria hybrida, are richly supplied with
long bristles, and interspersed amongst these may be seen a large number of shorter
bristles which are about two or three times as long as the prickly hairs of Pul-
monaria officinalis. A very instructive example is also afforded by the hybrid
Rhododendron intermediwm, which is easily produced by crossing the two Alpine-
Roses (Rhododendron ferruginewm and Rhododendron hirsutum). The upper
faces of the leaves of R. ferrugineum are dark-green, smooth, and shining, whilst
their backs are rusty and dull owing to the presence of a dense crowd of tiny scales.
The margins are not ciliate. The leaves of R. hirsutwm are light-green and beset
with scattered whitish glands (see vol. i. p. 232, figs. 54° and 54°), and their margins
are fringed with long hairs. In Rhododendron intermedium both kinds of epider-
mal appendage are displayed side by side. The under surface of the leaf is furnished
with brown scales, though not so profusely as in Rhododendron ferrugineum, and
its edge is fringed with hairs, but not so thickly as in R. hirsutum. The same sort
of thing occurs in Roses, Cinquefoils, Blackberries, Drabas, Hawkweeds, and many
other plants. Where one parent Rose bears only non-glandular and the other only
glandular hairs the hybrid is sure to be clothed with a mixture of the two kinds
of hairs. Several species of Cinquefoil (Potentilla) have stellate or tufted hairs,
whilst others are entirely free from them and bear none but simple hairs on their
leaves. In hybrids derived from two of these species—one with compound and the
other with simple hairs—stellate or fasciculated hairs are invariably intermixed with
a large number of simple hairs. A few species of the perennial Whitlow-grasses
(Draba), which are indigenous to mountainous districts in Central Europe, have
rectilinear anvil-shaped hairs, whilst others have three- or four-rayed stellate hairs.
In the hybrids which spring from these different species rectilinear and stellate
hairs grow together on the same leaf. If the hairs of two parent-species are of the

MINUTE STRUCTURE OF HYBRIDS. 565

same form but of unequal length, those of their hybrid offspring have a length
which corresponds approximately to the mean between the lengths in the parent-
species. Thus the length of the hairs on the backs of the leaves is 03 mm. in
Salix aurita, 12 mm. in Salia repens, and 0°6 mm. in their hybrid Salia plicata.
The hairs in Salia Caprea measure 0°8 mm., in Salia viminalis 03 mm., and in
Salix acuminata, their offspring, 0'5 mm. Whenever one stock is glabrous and the
other hairy, one may be quite sure that the corresponding parts of their hybrid will
be furnished with hairs, but less profusely than the parent-species from which that
particular characteristic is derived. This is the case, for instance, with Primula
Sturvi, the hybrid produced by crossing the glabrous Primula minima with Pri-
mula villosa, which has glandular hairs. The leaves of the latter are thickly
covered with these hairs, which vary from 0°7 mm. to 1 mm. in length, and Primula
Stwria has scattered glandular hairs which measure 0°3 mm. The hybrids obtained
by crossing the Purple Willow (Salix purpurea) with the Common Osier (Salix
vuminalis) are distinguished by Botanists into two sections, one of which—Salia
rubra—approximates to the Purple Willow and the other—Salia eleagnifolia—to
the Common Osier. The leaves of the Purple Willow when mature are glabrous at
the back, those of the Common Osier have small glistening hairs lying appressed to
their under surfaces, parallel to the lateral nerves, and measuring 03 mm. There
are about 1800 of these hairs on a square millimetre. The hairs of the hybrid
Salix eleagnifolia are of the same length as those of S. viminalis, but there are
only about 800 of them to the square millimetre, whilst the hairs of the hybrid
Salix rubra are somewhat shorter, and there are only 400 to the square millimetre.

Recently the discovery has been made by Wettstein that the form and dis-
position of the cells and tissues in hybrids is also a combination of the corresponding
characteristics in the parent-species. The various species of the Pine genus
(Pinus) may be distinguished with certainty by the anatomical structure of their
needle-shaped leaves, in particular by the thickness of the epidermal cells, the
number of the stone-cells lying beneath the epidermis, and the number of the resin-
ducts. In the hybrids the anatomical characters of the parents in these respects
are united, and the result is indeed often an exact arithmetic mean between the
two. Thus a needle of the Scotch Pine (Pinus sylvestris) contains from 6 to 10
resin-ducts, that of the Mountain Pine, Pinus Mughus (montana), contains from
3 to 5, and that of the hybrid offspring of the two from 5 to 7 such ducts. The
Junipers (Juniperus) afford a similar instance. In their case the leaves are dis-
tinguished by the various thickness and length of the layer of sclerotic-cells which
covers the back of each leaf, by the width of the resin-duct running through the
middle of the leaf, and by the number of the cells encasing that duct. In the
hybrids, such as Juniperus Kanitzii, which is produced by crossing Juniperus
communis and J. sabinoides, there is evidently a union of the parental attributes
in the corresponding cellular structures in the leaves. It has also been shown by
Hildebrand that in the Wood-Sorrel (Oxalis) hybrids also the anatomical characters
of the parents are united, but by far the most comprehensive study which has

566 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

been made in recent times into the minute structure of plant-hybrids is by Mac-
farlane. He selected a number of hybrids, and worked through their anatomy
from base to apex in the most painstaking manner. He dealt with roots, stems,
leaves, and the various portions of the flower, always comparing their various
tissues (both as regards size, form, and distribution) with those of their parent-
forms. And his result is to confirm what has been written above, though it is
obvious he had never read these pages. Amongst the more interesting of his
results may be mentioned those on starch-grains. Of course in a great many of
the parent-forms uniting to form a hybrid there is no recognizable difference in the
size or structure of the starch-grains. But in the genus Hedychiwm (belonging
to the family Zingiberaces) exceptions to this rule were found. Thus, those of
Hedychiwm Sadlerianum are intermediate in form and size between those of its
two parents, H. Gardnerianum and H. coronariwm; and those of a hybrid between
H. elatwm and H. coronarium exhibited similar intermediate characters.

It is important to note also that the aromatic substances and colouring matters
produced in the cells of a hybrid are inherited partly from the maternal, and partly
from the paternal stock. As we have several times already had occasion to mention,
the various species of the Rose genus may be recognized at once by their peculiar
scent. The perfume of Rosa Centifolia is the one which in particular is understood
by the rose-scent, but it is very different from that of Rosa alpina, and the latter in
its turn is unlike any of the scents emitted by Rosa arvensis, R. Gallica, R. Indica,
&e. Rosa Nasterana has a scent strongly resembling that of Pinks, whilst Rosa
lutea and R. punica are notorious for their disagreeable smell. Now the hybrid
Roses emit odours in which the scents of the parent-species are merged together in
a great variety of ways. Usually the scent of one stock predominates, and there is
only a suggestion of the other. Sometimes, however, an entirely new scent is
evolved from the fusion of the two, as is the case, for instance (according to Mac-
farlane), in Hedychiwm Sadlerianwm, the hybrid between H. Gardnerianum and
H. coronarvum,; and, again, in other cases, one of the component odours is inten-
sified and the other is extinguished. The same statement applies to the aromatic
substances to which the scent of the foliage is due. The hybrids of Rosa
glutinosa, Rosa rubiginosa, and R. rugosa, with Rosa Gallica and R. Centifolia,
are very interesting in this connection. The aromatic substances which are con-
tained in fruits and excite our nerves of taste are also inherited, partly from the
maternal and partly from the paternal stock. Owing, however, to the difficulty of
naming the various sensations of smell and taste it is of little use to discuss the
subject more fully.

As regards the colouring-matters reproduced in hybrids the first point to notice
is that in cases where the foliage is of different shades of green in the parent-species
the leaves of the hybrid exhibit a shade intermediate between the two. Conspicuous
instances of this are afforded by the hybrid Willows derived from Salia nigricans
and 8. purpwrea. In both these species the foliage becomes black when it withers,
and this characteristic is transmitted, though not in its full strength, to the hybrids

COLOURS IN HYBRIDS, 567

which S. nigricans and S. purpwrea form with other Willows whose foliage turns
brown when it dries up. The colour of the flowers in hybrids is usually the result
of a fusion of the colours in the parent-species; less frequently it is a mixtwre of the
original colours. The cases of fusion occur especially amongst the hybrids of
Orchids, Louseworts, Anemones, Pulsatillas, Medicagos, and Mulleins. If the tone
of the red or blue petals in one parent-species is dull and in the other bright, the
same colour reappears in the hybrid, but of a medium tone. Thus the colour of the
petals in Gymnadenia conopsea is rose-red and in Nigritella nigra dark blood-
red, whilst in their hybrid, Vigritella suaveolens, it is bright carmine. The corolla
of Pedicularis incarnata is of a subdued carmine tint, and that of P. recutita of a
dark reddish-brown, whilst their hybrid, P. atrorubens, has a dark purple corolla.
Where the floral colour of one parent-species is white and that of the other a full
yellow, red, or blue, the hybrid’s flower usually exhibits a pale yellow, red, or blue
coloration. The flowers of Anemone nemorosa are white, those of A. ranunculoides
golden-yellow, and those of their hybrid, A. intermedia, sulphur-yellow. The colour
of the flowers in a hybrid whose parents have yellow and violet, or blue flowers,
respectively, is very remarkable. Medicago media, which is the hybrid offspring
of the yellow-flowered Medicago falcata, and the blue-purple flowered M. sativa
very often has green corollas. The hybrids (Verbascwm commutatum, V. rubigi-
nosum, V. Schunidtit, V. versiflorwm, &e.) obtained by crossing the yellow-flowered
Mulleins with Verbascwm phenicewm, whose flowers are a conspicuous purple, all
display a bright brown tint in their corollas. The colour in question is just the
same as that which is produced by mixing gamboge with the purple prepared from
carmine and indigo. Quite a different tint is exhibited by the corolla of Verbascwm
pseudophenicewm, the hybrid generated by crossing V. Blattaria and V. pheni-
ceum. One of the parent-species (V. Blattaria) in this case has pale yellow and the
other (V. phoenicewm) violet-purple corollas, and in the hybrid (V. pseudophani-
cewm) the corolla is pale crimson. Nor are cases wanting in which hybrids have
been produced from forms with red and blue flowers respectively. The brilliant
scarlet-flowered Delphiniwm nudicaule has been crossed in the Edinburgh Botanic
Garden with the dark blue-flowered D. cashmirianum, the hybrid product being of
a lurid purple-red hue. Darwin obtained by crossing the red and blue Pimpernels
(Anagallis) a progeny some of which were blue, some red, and some intermediate
in colour. As a final instance of this colour-fusion may be cited the hybrid Pitcher-
plant Nepenthes Mastersiana. This hybrid is produced from N. sanguinea, the
pitchers of which are of large size and vary in colour from greenish-scarlet to
crimson, and of N. Kharsiana, which bears long narrow pitchers, varying from
yellowish-green to dull red-green. The hybrid (says Macfarlane) presents a
corresponding latitude in colour effect, though on the average it is greenish-crimson.

The hybrids which originate from crosses between Primula Auwricula, whose
flower is all of one colour, and Primula Carniolica, P. hirsuta, P. Oenensis,
P. villosa, &c., which have bi-coloured flowers, are also of great interest in this con-
nection. P. pubescens, the hybrid produced by crossing P. Auricula and P. hirsuta,

568 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

is the stock from which the garden Auriculas are derived. The colour of the corolla
in P. Auricula is a uniform golden-yellow excepting that at the throat, ae. at the
junction of the tube with the expanded limb, there is a floury efflorescence which,
like that covering the calyx, pedicels, and bracts, is due to a peculiar modification of
the epidermis. The corolla of P. hirsuta is bi-coloured; the segments of the limb
are violet-red, whilst the throat is white. The two tints are sharply marked off
from one another, and in consequence a white five-rayed star is seen in the middle
of the flower. There is in this case no trace of a floury efflorescence. In the
hybrid offspring of these two Primulas both the violet-red of the limb and the
white of the throat are blended with yellow; the former exhibits a touch of brown,
and in the middle of the flower is a pale-yellow star.

It is much less common for those floral colours which are inherited by a hybrid
from the parent-species to be displayed in juxtaposition than in a blended condition.
Since the time of the Roman Empire gardeners have crossed the red-flowered Rosa
Gallica and R. Damascena with the white-flowered Rosa alba and obtained thereby
hybrids in which the petals are striped and spotted longitudinally with red and
white (so-called “York and Lancaster” roses). Similar cases occur amongst hybrid
Calceolarias, Pinks, Petunias, and Wood-Sorrels, and instances of Tulip and Iris
hybrids are also known where the perianths exhibit the two different colours of the
parent-species side by side in streaks and patches. A hybrid of Iris Florentina and
I. Kochwi is especially deserving of notice. The perianth in £. Florentina is milk-
white and that of J. Kochii is dark violet. The hybrid of these two species was
first obtained in May, 1871, in the Botanic Garden at Innsbruck; one of the indivi-
dual plants thus produced had two of the outer and one of the inner members of the
perianth shaped like those of I. Kochii and of a deep violet colour, and one of the
outer and two of the inner members shaped like those of J. Florentina and milky-
white in colour. This arrangement of colours re-appeared year after year until in
1877 a single flower, in which the lower white members had some dark violet
streaks widening out from the middle to the edge of the perianth also made its
appearance. A second plant of the same hybrid developed flowers which only
differed from those of I. Florentina in that a few of the white petals had dark
violet streaks widening out towards the circumference. An equally noteworthy
case is that of a hybrid reared in the Botanic Garden at Florence from I. Ger-
manica and I. sambucina, of which a specimen was sent to me in 1872. One
inferior and two superior perianth-members displayed on one half of their surfaces
the colour and pattern peculiar to I. sumbucina, and on the other half those charac-
teristic of I. Germanica. The rest of the perianth could not be distinguished
except by its smaller size from that of Iris Germanica.

It must not be supposed, however, that the presence of variegated stripes,
patches, or speckles on petals is always an indication of hybridity. Véola poly-
chroma, a very common Alpine species, not infrequently produces simultaneously
two, three, or four open flowers, every one of which presents a different mixture of
tints, and amongst plants of this species covering only a small patch of ground it

GRAFT-HYBRIDS, 569

would be easy to find 100 blossoms with corollas differing from one another in the
distribution of their colours and in the arrangements of the spots and streaks upon
them. Similar phenomena are exhibited by Iris pumila and Polygala amarella.
The flowers in Polygala amarella are equally blue and white or sprinkled with
blue and white, and it is also no rare thing for plants to bear white flowers
interspersed with a few which are sprinkled with blue. In the same way several
species of Anthyllis, Euphrasia, Galeopsis, Linaria, Melittis, Ophrys, Orchis,
Saxifraga, &¢., exhibit considerable variation in the colours and markings of their
petals, which yet is not to be attributed either to hybridization or to the influence
of soil or climate. Reference must also be made here to the large number of species
(already mentioned on p. 194) in which the floral coloration is by turns blue and
white, red and white, blue and red, yellow and white, and soon. Heterochromatism,
ae. the change in the coloration and marking of petals, serves, in fact, in some
plants as a specific character. Contrasting with these heterochromatic species are
those with homochromatic flowers, which, as far as experience has shown, invari-
ably present the same colour and pattern, and only exhibit a slight variation in the
depth of the colour when subjected to the influence of light of varying degrees of
intensity. Jris Kochii and I. Florentina, Primula Auricula, and P. hirsuta,
together with other pairs of species referred to above as the progenitors of hybrids
of special interest, belong to the category of plants possessing homochromatic flowers,
and it is obvious that in the hybrid offspring of such plants the floral coloration
would be an important sign of identity.

This will be the most convenient place in which to introduce a few words
concerning the Bizzaria of Italian gardeners, and also concerning so-called graft-
hybrids. The name of Bizzaria has been given by the Italians to an extremely
curious Orange. Gallesio (1839) states that this Orange-tree produces at the same
time foliage, flowers, and fruit identical with the Bitter Orange (Citrus Aurantiwm)
and with the Citron of Florence (Citrus medica), and likewise compound fruit,
with the two kinds either blended together, both externally and internally, or
segregated in various ways. In the fruits of the Bizzaria which I have seen, five
longitudinal stripes of the colour of a Citron were interpolated in the fruit of the
Orange. Other fruits were, on the whole, like Oranges, excepting as regarded an
eighth of their mass, which in form, colour, and taste resembled a Citron, and was
also peculiar for its extreme convexity. This anomalous segment stretched in the
form of a light-coloured cushion from one pole of the spherical fruit to the other.
Growers maintain that the Bizzaria is the result of a cross between Citrus medica
and Citrus Awrantiwm, though the gardener who, in 1644, in Florence, raised this
tree, declared it was a seedling which had been grafted, and after the graft had
perished the stock sprouted and produced the Bizzaria (according to which
account it would be a graft-hybrid). In other similar cases of Citrus hybrids, how-
ever, such as the Bergamot Orange, alleged to be a hybrid of the ordinary Lemon
and the Bitter Orange, one finds the characteristics of the parent-species do not

570 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

reappear in juxtaposition (as in the Bizzaria), but are united or fused together.
Whether the case of Bergamot Pears, which are striped green and yellow, and that
of the half dark- and half light-coloured grapes, of which a few occur occasionally
in otherwise ordinary bunches of the fruit, are to be looked upon as parallel
phenomena to that of the Bizzaria must remain uncertain until it has been ascer-
tained to what particular crosses of the various species of Pyrus and Vitis the
innumerable Pear-trees and Vines now cultivated owe their origin.

Over and over again gardeners have asserted that hybrids may also be pro-
duced by budding and grafting, and in order to distinguish plants so arising from
those which are the result of a cross (i.e. from true hybrids), they are called graft-
hybrids. One of these plants, a Laburnum named Cytisus Adanvi, which exhibits
a curious mixture of the characteristics of Cytisus Laburnwm (the ordinary yellow
Laburnum) and Cytisus purpureus in the same individual, has been the subject of
lively discussion in scientific circles. It is indeed difficult to imagine anything
more curious than a plant of Cytisus Adamt. Most of the flowers derive their
characters equally from both parent-forms; the calyx is not so thickly clad
with silky hairs as in C. Labwrnwm nor so smooth as in C. purpureus, and the
corollas are of a dirty-red colour, compounded of the purple of C. purpureus
and the yellow of C. Laburnwm. But the curious thing is that on many of the
racemes a few blossoms of different appearance are interspersed amongst these red
flowers, some having yellow corollas and silky-haired calices as in C. Laburnum,
and others, still more remarkable, having half their petals like C. purpwreus and
half like C. Laburnum, or a third of their petals like C. pwrpureus and two-thirds
like C. Laburnwm, or some one of many other combinations. According to
Schnittspahns, this anomalous form of Cytisus was first produced at Vitry, near
Paris, in the year 1826, by a grower named Adam, who inserted a bud of C. pur-
pureus into a stock of C. Laburnwm. The shoot which sprang from the bud was
not a pure branch of C. purpureus, but had characteristics derived both from
C. purpureus and from C. Laburnwm. Buds for propagating C. Adami were sent
from Vitry to gardens all over Europe, and were in some cases inserted into stocks
of C. Laburnum, and in other cases into stocks of C. Jacquinianus and OC. alpinus.
In many cases gardeners grafted buds of C. purpwreus in addition to those of
C. Adami on to the same stocks, and thus produced shrubs of most extraordinary
appearance, Of the branches some resembled C. Laburnum, CO. Jacquinianus, or
C. alpinus, others Cytisws Adami, and others again C. purpureus; and amongst
the racemes were many which bore the ordinary flowers of C. Adami, interspersed
with a few blossoms of C. Laburnwm, and others in whose flowers a mixture of
the properties of C. Laburnwm and 0. purpwreus was apparent. The fact of main
interest, however, is that cuttings from Adam’s original plant (the alleged graft-
hybrid of C. Laburnwm and C. purpureus) should bear not only flowers of an
intermediate type (as might be looked for in a hybrid), but that on certain branches
the flowers break back (or revert) to the pure form of one or other of the parents,
or that a single flower should exhibit on one half the characters of one parent and

GRAFT-HYBRIDS, 571

on the other those of the other parent. Thus the alleged graft-hybrid bears three
distinct sorts of flowers, and often parti-coloured combinations of the two parent
forms. The anatomical details of the tissues of the Adami-forms have been
examined and compared with those of the two parent-forms by Macfarlane. It
appears that the tissues show a remarkable mingling of the two parent-forms. In
some the one, in others the other parent-form predominates. Though in the
flowers (ze. the pure Adami-flowers) the mingling is quite consistent with its being
a well-balanced seed-hybrid, in the vegetative regions the strikingly diversified
intermixture of tissues is unlike that met with in any seed-hybrid hitherto
examined. It should be mentioned that where the Adami-plant bears Laburnum
or purpwreus shoots and flowers the anatomical characters of these shoots is
identical with the normal C. Laburnum and C. purpwreus, respectively. Finally
the Adami-flowers never ripen seeds (the ovules being malformed), though when
the parent-forms occur upon it they ripen fruit and seed.

As a general rule the relations of the graft to the substratum (or stock) are very
different from those manifested in the case of Adam’s experiment. The shoot de-
veloped from the ingrafted bud makes the same use of the substratum in which it
is imbedded as a parasite makes of its host-plant (see vol. i. p. 213). It procures
from the substratum a supply of “crude sap”, and this material is absorbed and
worked up by the protoplasts of the cells of the graft in the same way as the liquid
substances of the soil which are sucked up by roots. It must be premised that those
cells of the graft which take up the crude nutrient sap are adapted to their work in
very much the same way as are the suction-cells of roots, that is to say, they are able
to exercise a selective power, and only admit such substances as are good for the
species to which the scion belongs. Any influence that the substratum might have
on the graft could scarcely be other than such as would be exercised by soils of
various composition. At the most we should expect variations in shape and colour,
which have no permanence, and are not retained by the scion’s posterity. As a
matter of fact, if, for instance, cuttings are taken from an Apricot-tree and grafted
on to various other Amygdalex, or are transferred from a Pear-tree to Quinces,
White-thorns, and other Pomacex, they do not exhibit the slightest alteration in
fruit, flowers, or foliage after entering into organic union with the stock. Again,
when hybrid Roses produced by crossing are propagated by budding and grafting,
the result is the same whatever species of Wild-rose is taken for the substratum or
stock. In all the thousands of cases of propagation by these means none has been
observed in which the stock has had any essential influence upon the form of the
scion.

In 1876 and 1877 certain experiments were made in the Botanic Garden at
Innsbruck on the genus Iris. They were suggested by the fact of the production
of the hybrids of that genus already referred to, and consisted in grafting buds
from the root-stock of one species of Jris on to that of another species of the same
genus. The experiment was attended with perfect success, but the shoots and
flowers developed from the ingrafted buds showed no trace of any influence on the

572 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

part of the substratum. Buds of Iris Kochii grafted on I. Florentina produced
unaltered plants of J. Kochii, and buds of I. Florentina grafted on I. Kochu
developed simply plants of J. Florentina. In the Botanical Garden at Vienna
there is a male Ginkgo-tree (Ginkgo biloba) which, more than a hundred years
ago, was the subject of an important experiment. When the tree was still quite
small the bud of a female tree was grafted upon it by Jacquin, and a lateral branch
was developed from this bud. What we have now is a mighty tree with a number
of branches bearing male flowers, and one large branch bearing female flowers. The
notable thing about the tree is that the grafted branch follows a course of develop-
ment which is obviously different from that of the stock. Every year in the spring
it puts forth foliage about fourteen days later than the male branches, and in the
autumn its leaves are still green long after the rest have turned yellow and, for the
most part, fallen off. From this instance we may infer that the shoots developed
from the grafted bud adhere with the greatest tenacity even to individual charac-
teristics, and do not suffer the substratum to affect them even in respect of their
annual development.

These facts have of recent years led many people to the opinion that the genesis
of graft-hybrids is simply a gardener’s story, and that even the most famous of the
supposed graft-hybrids—Cytisus Adami—does not owe its origin to budding, but
to a cross between Cytisus Laburnum and C. purpwreus. Still, in view of the
curious mixing of the parent-characters in Cytisus Adami, as revealed by Mac-
farlane’s investigations, it would perhaps be well to suspend our judgment. It is
true that even in true seed-hybrids (eg. the Iris hybrids mentioned on p. 568) a
mixing (not a fusion) of the parental characters of the flowers was observed. Fresh
observations in this field are wanted, directed especially with a view to showing
whether or not the sum-total of the characters of Cytisus Adami are absolutely
unique amongst hybrid-plants of whatsoever origin.

A further instance of the same nature may be mentioned, as it has been the
subject of careful scientific investigation and experiment. In 1876 a Jerusalem
Artichoke (Helianthus tuberosws) was grafted upon a Sunflower (Helianthus
annuus) in the neighbourhood of Bristol, and it was alleged that as a consequence
the Sunflower stock had acquired from the Artichoke the property of producing
tubers on its subterranean portions. Quite lately a series of buds of the Artichoke
were grafted on Sunflower stalks by Véchting, and the results carefully followed.
Tt was not found that the properties of the one were in any instance transmitted to
the other, although scion and stock grew together in perfect harmony.

The importance of this subject is so great that I cannot refrain from trespassing
for a moment on the domain of Zoology in order to refer to a case which shows that
the animal world also sometimes affords instances of the characteristics of both
parents being manifested in juxtaposition in their hybrid-offspring instead of being
merged together or united in close combination. Tetrao medius is well known to
be a hybrid produced by a crossing between the Black grouse (Tetrao tetrix) and
the Capercailzie (Tetrao Urogallus). This hybrid is so common in Tyrol that the

GRAFT-HYBRIDS. 573

poulterers in Innsbruck receive for sale on an average six specimens every year
from huntsmen in the immediate neighbourhood. The plumage of some individual
examples of Tetrao medius is curiously striped with alternate groups of feathers
inherited from 7. tetria and T. Urogallus respectively. In 1879 a huntsman brought
me from the remotest part of the Gschnitzthal in Tyrol a hen of Tetrao medius
whose plumage exhibited a mixture of the feathers of 7. tetrix and T. Urogallus,
irregularly distributed in stripes and patches all over the body. The case of this
hybrid affords valuable confirmation of the results of the experiments made on
Iris hybrids, and there can no longer be any doubt of the fact that there are hybrids
generated by crossing in which the parental characters reappear in juxtaposition.

In spite of all this, however, I should not like to deny the possibility of the
existence of graft-hybrids, for there are certain considerations which tend to a con-
trary conclusion. In most cases the relation to the substratum of those cells of the
ingrafted shoot or bud which take the crude nutrient sap from the stem of the
stock-plant is just the same as that of a parasite’s suckers; they are clearly marked
off from the cells of the substratum and are not influenced thereby either in their
shape or in their ultimate structure, whilst, conversely, no essential modification is
undergone by the substratum through the presence of the graft. There is nothing,
however, to exclude the possibility of a fusion between the protoplasmic contents of
adjacent cells taking place at the spot where stock and graft unite, and the con-
sequent development of a tissue which is composed of cells arising from a division
of the cells containing the mixed protoplasms, and which unites the characteristic
features of the tissues belonging to the stock and to the graft respectively. In fact,
something of the kind has been observed in the case of the parasitic Balanophoresze
(see vol. i. p. 194). Now supposing such an intermediate tissue were to be formed
at the junction between a graft and its substratum, one or more shoots might spring
from it and they would doubtless combine the characteristics of the two species.
employed as stock and scion.

In relation to the genesis of new forms of plants in nature, the question of the
possibility of the existence of graft-hybrids is of secondary importance; but it is of
no small moment in connection with the comprehension of the processes involved in
hybridization; for, the researches suggested by this problem have led to the con-
clusion that the marks and attributes of a particular species which are percep-
tible to our senses are an outward sign corresponding to the ultimate structure
and molecular composition of a specific protoplasm, and that wherever the special
characters of two species are united in a single plant-form, that form is built up
from protoplasm which owes its origin to a combination of the protoplasms of two
parent-species.

It is only by adhering to this train of thought that one is able to understand
how it is that, also in the matter of chronological development, the vital manifesta-
tion connected with the shape, anatomical structure, scent, and colour occupy in
hybrids a position intermediate between the corresponding manifestations in the
parental species. In the Botanic Garden at Vienna there has been for many years

574 THE GENESIS OF NEW FORMS AS A RESULT OF CROSSING.

a Buckthorn-shrub, named Rhamnus hybrida, which sprang from a cross between
Rhamnus alpina and Rhamnus Alaternus. One of the parent-species, R. alpina,
has deciduous foliage, i.e. leaves which are green in the summer and wither and drop
in the autumn; the other, R. Alaternus, has evergreen leaves, which last through
the winter and remain on the branches for two years. The hybrid, R. hybrida,
possesses leaves which do not fall off in the autumn, nor yet last fresh and oer for
two years, but which maintain their verdure through one winter and fall in the
spring when new shoots are sprouting from the buds. The behaviour of hybrids
as regards their season of flowering is also very remarkable. From vis to 1874 I
kept notes concerning the flowering of some fifty different kinds of Willow, growing
in the Botanic Garden at Innsbruck, and each year made an entry of the day on
which the first flower opened in each plant, whether a pure species or a hybrid.

EARLIEST DATE OF FLOWERING OF A NUMBER OF WILLOWS GROWING IN THE
BoraNiIc GARDEN AT INNSBRUCK.

(The date given is the average for 12 years.)

Salix Cremsensis March 17 | Salix Caprea March 16 | Salix daphnoides | March 18
» Mauternesis » 23 » Caprea » 16 »» purpurea ml. 7
» attenuata » «=—-25 » Caprea - » 16 » grandifolia- | March 27
» Wimmeri » 26 » daphnoides » 18 » Incana April 17
, Austriaca April 3 » grandifolia - a 2a » purpurea 3 7
» Seringeana 4 3 » Caprea » 16 » Incana » 17
» capnoides 4 5 » cinerea - April 10 » incana ee Wi
» Intermedia i" 6 » grandifolia - March 27 » Incana Pee)
» rubra - ) 6 » viminalis April 3 »» purpurea - 7
» Kerneri » LO » Viminalis , 3 » Incana Bon ale
» Oenipontana » 12 » purpurea 3 7 » incana ay Oe
» auritoides » 14 » purpurea » 7 » aurita » 19
» Fenzliana » 2 » retusa 3 21 » glabra - sg
», retusoides 3 «0s 2. » retusa 5 2k » vacquiniana ae
» alpigena - » 238 » retusa 3 ol » hastata 3 Oot
» excelsior - » 23 » fragilis » 18 » alba - - » 27
» Ehbrhartiana » 29 » alba - 3. 2h » pentandra- |May 6

The name in the first column is that of a hybrid in each case, and the names on the same line in the second and third
columns are those of its parent-stocks.

The above table, which gives the means of the dates recorded in 12 years of the
first opening of the male flowers in 15 species and 17 hybrids produced from them
by a variety of crosses, shows that the hybrids invariably flower on days between
those on which the parent-species enter upon that stage of development. It will be
observed that the two alpine Willows, Salix retusa and Salia J acquiniana, flowered

on an average in the 12 years on the same day, and that their hybrid Salix
retusoides kept also to that date.

We have hitherto dealt with those of the marks, attributes, and vital phenomena
manifested by hybrids which are derived partly from the one parent-species and
partly from the other, and we must now pass to the consideration of such character-
istics as cannot be attributed to inheritance from those species. There is, in the
first place, the fact that the majority of the hybrids produced from crosses develop

CERTAIN CHARACTERS OF HYBRIDS. 575

with striking rapidity and exuberance; they not uncommonly flower the very first
year after they are sown, whereas the seedlings of the parent-species may not attain
to the flowering stage for two or three years; and in respect of the size of the
foliage, and still more that of the flowers, hybrids often exceed both parent-species.
The latter circumstance is indeed one of the chief reasons why growers make such
frequent use of the process of crossing. They are thus enabled to meet the demands
of connoisseurs, who prefer to have plants with conspicuous flowers in their gardens.
The augmentation in the size of the flowers usually ceases after the first, or at any
rate after the second year. Subsequently, the flowers of hybrids become smaller
again. On this account gardeners are in the habit of producing such hybrids as are
especially valued for their large flowers over and over again by the original method.
Of the large number of observations recorded on this subject we will here mention
one as an example. Isoloma Decaisneanwm of the order Gesneracee is the product
of a cross between Isoloma Tydewm and Isoloma sciadocalyx. The seeds obtained
after crossing germinate early, and the seedlings develop rapidly into exceptionally
robust plants. The foliage-leaves are three times as large and the flowers twice as
large as those of the parent-species; in addition, the flowers are much more numerous
than on the parent-plants, and in consequence the hybrid has a much more imposing
and showy appearance than either of its progenitors.

Many plants which grow on soil rich in humus in mountainous regions, such as
the Lungworts (Pulmonaria) and Primulas (Primula), do not thrive particularly
well in gardens, and certain species die after a short time even when cultivated
with the greatest care. Yet the hybrids of such species flourish wonderfully well
under similar circumstances. They blossom luxuriantly, and may be kept in a
state of vigorous growth for many years. Examples of this are afforded by
Primula pubescens and Primula Venzoi. One of the parent-stocks of P.
pubescens, viz. Primula hirsuta, can only be reared if the soil used is expressly
prepared for itself, and if several other special precautions are taken, whereas the
hybrid, P. pubescens, grows exuberantly in ordinary garden-soil. The case of P.
Venzoi, the hybrid-offspring of Primula tyrolensis and Primula Wulfeniana, is
still more remarkable. Although both the parent species are reared with difficulty,
even when the greatest care is bestowed upon their cultivation, Prumula Venzor
will flourish with extreme luxuriance if planted close to them in the same soil and
under the same external conditions.

Another phenomenon sometimes exhibited by hybrids is a change in the dis-
tribution of the sexes. It often happens, for instance, that hybrids produce
pseudo-hermaphrodite female flowers and pseudo-hermaphrodite male flowers (ef.
p. 294), even: where both parent-species have true hermaphrodite flowers. In
Willow hybrids a partial transformation of male into female flowers, and vice
versd, has been not infrequently observed, and we then have moncecious catkins
bearing flowers, half of which are female and half male. This change also occurs
in true species, but only as a rare exception, whilst in the case of hybrids it is by
no means uncommon.

576 THE GENESIS OF NEW SPECIES.

Hybrids also exhibit the phenomenon known as the “doubling” of flowers,
which depends upon the transformation of stamens into petals, independently of
the action of tiny gall-mites, which are the frequent cause of doubling in other
plants (cf. p. 548). Several hybrid Roses, Pinks, and Camellias are only known
with double flowers.

It is difficult to explain the fact, repeatedly confirmed by observation, of the
appearance in hybrids of characters which are not present in either parent-species,
or rather which cannot be traced to inheritance from either of those species. Thus
it sometimes happens that individual plants of a hybrid develop sinuate foliage-
leaves with wavy outline, though in both of the parent-species the leaves are either
entire or only slightly toothed. The hybrid Salvia sylvestris occasionally exhibits
deeply sinuate radical leaves, whilst Salvia nemorosa and Salvia pratensis, the two
species to which it owes its origin, never do so. Another instance of the same kind
is that of a Stock, the hybrid of Matthiola incana and Matthiola Maderensis.
Neither the one nor the other parent-species has sinuate leaves, yet here and there
plants of the hybrid display foliage with the margins so deeply cut as to remind one
at first sight of Matthiolu sinuata. Again, in Primula pubescens the leaves are
sometimes more deeply sinuate than in either Primula Auricula or Primula
hirsuta. In hybrids of the Foxglove genus (Digitalis), flowers not infrequently make
their appearance wherein the corolla is produced underneath into a spur as in the
Toad-flax (Linaria). One hybrid produced by crossing two species of Water Lily,
Nymphea Lotus and Nymphea dentata, displayed dark violet lines on its sepals
which are not to be seen in either parent-species. Reference must also be made to
the comparative frequency with which hybrids bearing white flowers spring from
species with blue, violet, red, or yellow blossoms whose non-hybrid offspring only
produce colourless flowers on very rare occasions. Lastly, we may mention the fact
that as from species so also from hybrids varieties may be formed; but they
have no permanence amongst the descendants of a race, passing into other varieties
whenever it undergoes the restrictive influence of a change in external conditions.

3. THE ORIGIN OF SPECIES.

Genesis of New Species.—Derivation of Existing Species.—The Sub-divisions of the Vegetable
Kingdom.

THE GENESIS OF NEW SPECIES.

It is now more than forty years since I discovered, on an island on the Danube
not far from the little town of Diirenstein, a Willow which had till then remained
unknown to Botanists. The plant in question was growing on the island in com-
pany with a number of other Willow-trees and Willow-shrubs belonging to the

THE GENESIS OF NEW SPECIES. 577

species known as Salix incana and Salix daphnoides respectively, and it was
apparently intermediate in form between those two species. The hairs, the system
of ramification, the foliage, and the flowers resembled those of S. incana in some
respects and those of S. daphnoides in others, and a single glance would have
led any unbiassed observer to conjecture that he had to deal with the product of
a cross between these two species.

This discovery,' made in one of the first years of my career as a student of
Botany, chanced upon a time when Botanists were beginning to take a particularly
keen interest in all cases of intermediate forms observed growing in a state of
nature. Some of the leading men at that time refused to believe in the existence
of any wild hybrids, and were of opinion that the supposed cases were varieties of
species whose presence was to be explained by a tendency in the plant itself to
change its form. They also held the view that all plants between which one or more
intermediate forms had been found to exist were to be included in a single species,
and, in accordance with this, they not infrequently treated three, four, or more kinds
of plant previously classed as distinct species as being really “varieties” of a single
species, because forms obviously intermediate between them, ‘.e. so-called “transitional
forms”, had been discovered. This practice was carried so far that several systematic
Botanists of that day included in one species 5, 10, and even 15 distinct Hawk-
weeds which had been previously described as separate species, the reason for the
change being that they were all linked together by transitional forms. Another
school of Botanists, on the other hand, recognized in most of the so-called transi-
tional forms the results of natural crossing, but they did not deny the existence in
plants of a capacity to form varieties in the Linnean sense in response to changes.
of soil or climate.

To my mind even at that time there could be no doubt which of the two oppos-
ing theories concerning the genesis, significance, and position of intermediate forms.
was to be preferred. The discovery of the hybrid Willow referred to led to my
paying particular attention to plant-hybrids, and in the course of the last forty
years I have made extensive series of experiments to clear up many obscure points,
and to correct the prejudices which then prevailed.

One misconception as to the nature and significance of hybrids, which had great.
weight and found expression in the name of “bastard” assigned to them, consisted
in the idea that they were contrary to nature. The German word “bastart” is defined
by Grimm as a base and useless species. This prejudice was carried so far that.
Kant positively denied their independent existence, and believed they must neces-
sarily die out with the first generation. Connected with this notion was another,
according to which hybrids were destitute of the power of producing fertile seeds
and propagating their kind sexually. It probably arose from observation of the
hybrids of the Mullein genus (Verbascwm), which in Central Europe are so common

1The little paper recording the finding of this Willow, with some additional remarks, by Anton Kerner, was
published in 1852 (Vienna, Zool. Bot. Ver. Verhandl. II., 1852), This seems to have been Kerner’s second

definite contribution to science; what would appear to be his first is printed in the same publication a few

months previously.
Vou. II. 87

578 THE GENESIS OF NEW SPECIES.

and conspicuous that they were accepted as the results of crosses between two
species even by those amongst the earlier Botanists who were most disinclined to
recognize the existence of plant-hybrids. Now, these Mullein hybrids do not for
the most part mature any seeds. The pistil itself is usually incompletely developed,
and even if one or other of the fruit-capsules does develop, the ovules in it are
abortive and infertile. Nevertheless it would be erroneous to say that no Mullein
hybrid has ever produced seeds capable of germination. Two such hybrids were
artificially generated in my garden, viz.:—Verbascum rubiginosum, by crossing
Verbascum Austriacum with the pollen of Verbascum pheniceum, and Verbascum
pseudophaniceum, by crossing Verbascum Blattaria with V. phanicewm. The
former of these hybrids, it is true, never produced seeds capable of germination;
but in the case of the second, although most of the capsules were empty and
abortive, a few containing fertile seeds ripened; so that even the hybrids of
Mulleins are not invariably sterile.

Anyone who will look beyond the limited range of that particular genus will be
convinced that in respect of their capacity for sexual reproduction hybrids do not
differ essentially from plants which have been admitted to be “true”, permanent
species by Botanists of all periods. For the case of a few of these true species, as,
for instance, Cochlearia Armoracia, Crambe tataria, Lilium bulbiferwm, Lysimachia
Nummularia, Rubus odorus and R. Nutkaensis, it has long been known that if the
stigmas are dusted with pollen from the stamens in the same flowers very few seeds,
if any, are set, whilst pollen from other flowers is obviously preferred by them. On
the other hand, there are true species whose flowers are pseudo-hermaphrodite, 1.¢.
they have the appearance of being bisexual, but are really unisexual (cf. p. 294).
In one individual we find that the ovaries are fully developed, as also the stamens,
but that no pollen capable of fertilizing ovules is produced in the anthers; in
another plant the ovaries are imperfectly developed, whilst the anthers are filled
with effective pollen. For seeds to be set in such circumstances two individuals at
least are requisite, and pollen from a plant bearing pseudo-hermaphrodite male
flowers must be transferred to the stigmas of the pseudo-hermaphrodite female
flowers. Now hybrids with pseudo-hermaphrodite flowers also exist, and in their
ease, as in that of true species, two kinds of individual are requisite to produce
seeds capable of germination. Supposing, however, in such a case that the two
kinds of plant necessary for reproduction do not grow close together or do not
flower simultaneously, or that one of them is altogether absent—a contingency which
must often occur—fertilization cannot be effected, and consequently no seeds can be
formed. It is scarcely necessary to amplify the proposition that dicecious hybrids
behave in this respect in the same manner as true species, and that pollination and
fruit-formation may in them be impeded likewise by dichogamy or by hetero-
stylism. In many hybrids, again, as in true species, the relative positions of
stamens and pistil, the height of the stigma, the length of the filaments, and other
conditions of the kind are not conducive to autogamy, and consequently no trans-
ference of pollen from the anthers to the stigmas in the same flower can take place

THE FERTILITY OF HYBRIDS. 579

either at the beginning or at the end of the period of bloom. Such hybrids are
dependent upon foreign pollen, and if none is brought at the right time by wind or
insects no pollination or fertilization takes place, and no seeds are developed.

Even these brief references to recently-discovered phenomena connected with
fertilization are sufficient to indicate that the suppression of the function of fruit-
formation in hybrids is due in most cases to the same causes as.operate on true
species. Innumerable experiments have proved that if at the proper time pollen of
the right sort is placed upon the stigmas of hybrids fertile seeds are developed as in
the case of true species.

We must now consider a statement which for long held its place in Botanical
works owing to the positive manner in which it was enunciated by an eminent
authority. The proposition in question, whilst admitting the fertility of hybrids,
asserted that it was conditional on the stigmas being supplied with pollen from one
or other of the parent-stocks, and that no fruit was formed as a result of autogamy.
This assumption rested partly on certain series of experiments performed on garden-
Plants by the Botanist Koelreuter in the second half of the eighteenth century.’
By crossing two species of Tobacco-plant (Nicotiana rustica and Nicotiana pani-
cuwlata) Koelreuter produced a hybrid which in its characteristics was an exact
mean between the two parent-species. The stigmas in the flowers of this hybrid
were then dusted with pollen from one of the parents, and the result of this second
cross was another hybrid, the characters of which resembled those of the species
which supplied the pollen more closely than was the case with the first hybrid. The
same treatment was applied to the second hybrid, and thus, after three generations,
a plant was evolved completely resembling the male progenitor. The first hybrid
had, therefore, in a sense, “reverted” to that particular parent-species. The “rever-
sion” of the hybrid to the other parent-species was similarly procured after three
generations. Such a result could naturally not have ensued if the action of the
pollen of the parental stocks on the hybrid had not been entirely effectual. It is
accordingly quite true that hybrids are fertile when the pollen used to fertilize
them is taken from either of the parent-species, but the further assertion that they
are sterile if their own pollen is employed for the purpose is incorrect, at any rate
a8 a universal proposition. Koelreuter’s own conscientious experiments show con-
clusively that it is possible for hybrids to bring fruits to maturity as a result of
autogamy, and that, as a matter of fact, the majority do develop such fruits. We
may also refer to the large number of plants with ornamental flowers, such as
Begonias, Pansies, and Pinks, which every year in our gardens produce seeds auto-
gamously, and are reproduced in great numbers by means of those seeds (see p. 556).
Some interesting experiments have also been made on Medicago media, the hybrid
of Medicago falcata and M. sativa. This plant, which is, in many places, cultivated
on a large scale for fodder, is propagated continuously by seeds which are in a very

1 Joseph Gottlieb Koelreuter (1733-1806) was the first to investigate the question of hybridization scientifically
and thoroughly. His work, which ranks with the best of modern times, is contained in his Vorldéujige Nachricht
von einigen das Geschlecht der Pflanzen betreffenden Versuchen und Beobachtungen (published 1761-1766) ; a convenient
reprint was issued in 1893.

580 THE GENESIS OF NEW SPECIES.

subordinate degree, if at all, dependent on the parent-species for their production.
Nay more, it would be prejudicial were one of those species to supply the pollen
seeing that the fertility of this hybrid is diminished thereby. We have here a case
of a hybrid manifesting enhanced fertility as compared with one of its parents ; for
Medicago falcata is one of those Papilionacez in which autogamy is attended with
very small result. It has been ascertained that in cases where the flowers of that
species are thrown upon their own resources for pollen, out of every 30 flowers
only two or three fruits containing seeds capable of germination are matured. If
flowers of Medicago falcata are crossed with pollen belonging to another species,
such as Medicago sativa, a much larger number of fruits is produced, and it is
stated that the number of seeds is almost doubled. Medicago media usually sets
from six to eight pods in each raceme if the flowers depend upon their own pollen
for fertilization. If, however, pollen is brought to them from Medicago falcata
the degree of fertility is strikingly reduced; the flowers so crossed either remain
quite empty or develop pods whose seeds are not capable of germination. Medicago
media is therefore an instance of a hybrid which is actually injured by being
crossed with one of the parent-species, but is successfully reproduced by autogamy.
The upshot of all these experiments is that the results of autogamy are no different
in hybrids from what they are in species.

We may infer from the same experiments in what way reversions of hybrids to
their parent-species should be regarded. Botanists possessed with the idea that
every hybrid was the product of some process contravening the laws of nature
imagined that this anomaly must be counteracted, and that this was effected by a
tendency existing in the hybrid’s descendants to approximate sometimes to one and
sometimes to the other parent-species, so that in the course of a few generations
they would completely revert to the form of a true species. As the accounts given
by gardeners seemed to confirm the fact of the occurrence of such reversions, no
doubt was raised as to the soundness of this view. The reports of gardeners on the
subject were, however, founded on inaccurate observation, want of knowledge, and
self-deception. In former years the phenomena of pollen-transport in the case of
pseudo-hermaphrodite, dichogamous, and heterostyled flowers, and many other
things connected therewith, were not appreciated at their full value; to most
gardeners they were altogether unknown, and it was only in the rarest instances
that any measures were taken to preserve the species and hybrids reared in gardens
from extraneous pollen. The majority of growers had no suspicion that the fruit
formed on a particular cultivated hybrid might be due to the effect of pollen con-
veyed by the wad or by insects from one of the parent-species flourishing in the
vicinity, Bad if they noticed that the seedlings arising from that fruit exhibited
characteristics approximating to either of the parent-species they were in the habit
of calling the phenomenon a reversion. But if a gardener takes care that the flowers
of a hybrid newdes cultivation are only supplied with pollen developed in flowers of
their own kind whilst that of other species is excluded, the plants which arise from
the seeds of the hybrid exhibit the characters of that hybrid unaltered. Thus,

SPECIES AND RACES, 581

hybrids prove true to seed, to use a gardener’s expression, and there is no truth in
the assertion that they have an innate tendency to revert to one of the parent-
forms.

At one time the attempt was made to distinguish two sorts of hybrids—those
arising between species, which were regarded as sterile, and those arising between
races, which were regarded as fertile. By “races” are understood forms which, whilst
not differentiated by characters of sufficient importance to rank as species, are yet
reproduced by seed and transmit their characters to their offspring. They seem to
stand midway between what are called varieties and sub-species. Forms arising by
the crossing of species were termed hybrids, those arising by the crossing of races
“blendlings”. But in this matter Botanists argued in a hopeless circle. Firstly, it
was said that if races were crossed the intermediate forms were fertile; whilst those
springing from species were sterile; and, secondly, the distinction between races and
species was defined as consisting in the fact of the fertility of the intermediate
forms produced by crossing races, as compared with the infertility of those derived
from crosses between species. A distinction founded on such reasoning as this is, of
course, destitute of any value or meaning. What, then, is the difference between
races and species? There are certain forms which have a similar physiognomy, an
agreement in certain striking particulars. They are bound together by these common
characteristics into a single group, and it must be supposed that they are nearly
allied in respect of their origin also. But no more than affinity can be predicated
by characters which, though perhaps less striking than the others, are yet trans-
mitted unmodified to descendants and prove themselves to be constant attributes.
It has been sought to apply the term “races” to nearly akin forms of the kind. But
the degree of variation has nothing to do with the conception of a species; the
essential point is that the characters wherein the variation is manifested are trans-
mitted unchanged to the descendants, and this happens as a fact in all the cases to
which the name of race has been affixed. The use of the term would obviously
imply quite a different connotation of the name of species from that which Linnezus,
with logical exactitude, attached to it. According to him a species was not an
assemblage of individuals of the same form, but an assemblage of individuals of
different forms, constituting a group of units and not itself the unit of the system.
If, like the French system, we were to distinguish the groups of nearly allied
Species as “petites espéces ” from those exhibiting more marked differences and less
nearly akin to one another, which would be known as “grandes espéces”, that
would involve quite sufficient recognition of the difference which exists in various
degrees between members of the two categories in question; but the introduction of
the word “race” side by side with the word “species” suggests the idea of some line
of demarcation between the two such as does not in reality exist. Again, if there is
no definite boundary between race and species the separation of blendlings from
hybrids also fails, and with it the proposition that only those hybrids are fertile
which are the offspring of races.

In respect of fertility, then, there is no difference between hybrids and species.

582 THE GENESIS OF NEW SPECIES.

In the one as in the other we find those floral contrivances for bringing about cross-
fertilization in the first place and autogamy in the second, of which an account was
given in the first part of this volume; in the one case as in the other cross-fertiliza-
tion often takes place as a result of those contrivances, and both categories include
forms which are incapable of self-fertilization, and only develop fruits and fertile
seeds in consequence of geitonogamy or xenogamy. Seeing that it has been ascer-
tained also that, provided the pollen from other species is excluded, hybrids transmit
their form unchanged to their posterity, and that the substitution of brood-bodies
for fruits as a means of reproduction and the enhancement of the development of
those bodies in the event of there being no fruit, are phenomena common to species
also, we come to the conclusion that no line of demarcation between hybrids and
Species exists in respect of the function of propagation.

The consideration of all these facts led me years ago to raise the question
whether hybrids could originate species,) and to answer it in the affirmative.
Looked at from this point of view, the hybrids which have been and are being
produced in nature acquire a special significance, and it becomes important to form
a correct notion as to their existence, behaviour, and distribution in localities where
the life of plants is untrammelled and undisturbed. Only the vegetation of Europe
has been thoroughly studied in this connection, yet this alone affords a fund of
information, and we may take it for granted that what is true for Europe will
apply likewise to the other quarters of the globe,

We shall be rather below than above the mark if we estimate at a thousand the
number of wild hybrids belonging to the Flora of Europe which have been brought
to light during the last forty years. Of these only a small proportion are of the
class of Cryptogams, but this circumstance is due to the fact that it is only lately
that Botanists have paid any attention to hybrid Cryptogams. Future researches
will no doubt establish the hybrid nature of many so-called “transitional forms”.
Amongst Mosses in particular, several hybrids arising from species which grow in
ditches and marshy places (Hypnum aduncum, H. fluitans, H. lycopodioides, &e.)
have been discovered. A few hybrids of the genera Orthotrichum, Grimmia,
Physcomitriwm, and Fwnaria have also been identified. Fern hybrids are known
in the genera Aspidiwm, Asplenium, Ceterach, Polypodium, and Scolopendriwm.
Scolopendrium hybridum, which was observed in Istria, is especially remarkable
as being the result of a cross between two species possessing widely different forms
and included in different genera. The parent-species of this hybrid are, firstly,
Scolopendriwm officinarum, which is glabrous and grows in clefts in damp, shady
rocks and walls; and, secondly, Ceterach oficinarwm, which has the under surfaces
of its fronds thickly covered with brown scales and flourishes in the crevices of dry
walls exposed to the sun. Amongst the Horse-tails we may mention Hquisetum
anundatum, a rather common hybrid, which owes its existence to the crossing of
Equisetum arvense and E. limoswm.

In the division of the Conifere no less than seven hybrids have been recently

1Oesterreich. botanische Zeitschrift xxi. p. 34 (1871).

NATURAL HYBRIDS. 583.

identified, and this fact is of no little significance when taken in connection with
the circumstance that Europe only possesses 41 species of Conifers. Juniperus
Kanitzi, the hybrid offspring of Juniperus communis and J. sabinoides, is a very
instructive instance owing to the great diversity in the form of the two parent-
species.

Comparatively few hybrids occur amongst Grasses. The majority belong to the
genus Calamagrostis. Strangely enough, most hybrid grasses have arisen from crosses
between species of different genera, as, for instance, Festuca and Lolium, Triticum
and Elymus, Triticum and digilops. The hybrid derived from Myilops ovata and
Triticum sativum, and known by the name of Aigilops triticoides, and the hybrid
4igilops spelteformis, obtained by crossing Agilops triticoides with Triticum
satwwwm, have been the subject of lively discussion in their time, and have contri-
buted not a little to clearing up our ideas concerning hybrids. As a set-off to the
Grasses, the groups comprising Reeds, Rushes, and Sedges include a comparatively
large number of hybrids. For example, in the genus Carex instances have been
discovered in the most widely different localities.

Amongst Lilifloress and Iridex only a few wild hybrids have been found, but
on the other hand a large number occur amongst Orchidacee all over Europe. It
is striking how many of these Orchid hybrids spring from species which are placed
by Botanists in different genera. Hybrids are known, for instance, which are derived
respectively from Aceras and Orchis, from Anacamptis and Orchis, from Colo-
glossum and Orchis, from Gymnadenia and Orchis, from Himantoglossum and
Orchis, from Serapias and Orchis, from Gymnadenia and Nigritella, and from
Epipactis and Cephalanthera. The hybrid Epipactis speciosa, lately discovered in
the Erlafthal of Lower Austria, is the result of a cross between Epipactis rubigi-
nosa and Cephalanthera alba, and is of special interest on account of its manifesting
characters strongly resembling those of species indigenous to regions at a great
distance from the place where the hybrid occurs, for at first sight Epipactis speciosa
might easily be taken for Epipactis gigantea, which is a native of North America,
or for the Japanese species named Epipactis Thunbergit.

Hybrids are comparatively numerous amongst the Pond-weed group (Potamo-
geton). These are aquatic plants which discharge their pollen in the form of clouds
of dust, and at the season of pollination raise their flowers above the surface of the
water. Owing to their being completely protogynous (see p. 310), autogamy is out
of the question. The crossing of pairs of species is especially promoted by the
circumstance that the different species flower in definite succession, so that always
just at the time that one species is terminating its period of bloom another is
coming into flower.

Plants which have their flowers in catkins (amentaceous), such as Oaks, Birches,
Alders, Poplars, and Willows, produce an uncommonly large number of hybrids.
In Willows pollination is effected by insects, in the other genera by the wind. This
gives occasion for us to raise, in connection with this group, the question whether
hybrids originate more frequently from entomophilous or from anemophilous plants.

584 THE GENESIS OF NEW SPECIES,

The fact that many more than a hundred Willow hybrids are known looks as if the
agency of insects were the more favourable to hybridization. At the same time we
must bear in mind that the number of species of Willow in Northern and Central
Europe is very large, whilst the number of different Birches, Alders, and Oaks is
small. Taken in relation to the number of species, the hybrids belonging to the
plants last mentioned are no less numerous than those of Willows, and it appears,
therefore, that hybrids occur as frequently amongst plants whose pollen is dispersed
in the form of dust as amongst plants with adhesive pollen which is transported by
insects. The prevalence of hybrids amongst Pond-weeds points to the same conclu-
sion. A comparison between the Docks and Polygonums even indicates that in
anemophilous plants, such as the Docks, hybrids come into existence more readily
than in the case of entomophilous plants as represented by the Polygonums, for in
scarcely any genus is the number of hybrids so great in proportion to the number
of species as in the Dock genus, and the ratio is certainly higher than it is with the
Polygonums.

As regards the Caryophyllaces it is remarkable that Dianthus has many hybrids
and Silene few, although these two genera resemble one another in the distribution
of their sexes and in being chiefly visited by lepidopterous insects. In the genus
Viola hybrids are extremely common. It has been shown that many Violas which
were formerly designated as “transitional forms” are in reality hybrids, and thus
the grounds upon which systematic Botanists treated whole series of species as one
only are removed. As with the Violas in Central Europe so also with their allies
the Cistuses in the South, hybrids are numerous; several kinds of Cistus hybrid occur
so commonly that they were described as species by the Botanists of former times.

It is noticeable in the Cruciferee that no hybrids are formed in nature between
the numerous annual species of this family. There are also only a few hybrids
known which are derived from the perennial species. The genera Roripa and
Draba are, however, exceptional in this respect. The case of Ranunculacez is
similar. In the comprehensive genera Aconitum, Helleborus, and Ranunculus,
only a few hybrids have been identified with certainty, whilst in Anemone and
Pulsatilla there are almost as many hybrids as species. The case of the hybrid
Water-lily Nuphar intermediwm will be discussed later on.

Many hybrids are known in the genera Tilia, Hypericum, Malva, Rhamnus,
Pistacia, Acer, Euphorbia, and Epilobiwm, the last alone including fifty different
kinds. This makes it all the more remarkable that so varied a family as the
Umbelliferee yields very few hybrids. Of the numerous hybrids-belonging to the
Saxifragaceee we may mention as specially noteworthy those derived from species
which differ exceedingly from one another in form and size. One cannot easily
imagine two plants in the limits of a single genus which present a greater contrast
to one another in respect of flowers, leaves, and general mode of growth than is
exhibited in the following cases:—Sawifraga cesia and S. mutata, S. Aizoon and
8. cuneifolia, S. arzordes and 8. squarrosa, and yet hybrids have sprung from the
crossing of these species.

NATURAL HYBRIDS, 585

About two hundred hybrids, for the most part fertile, have come into existence
in nature within the family of the Rosacew. The genera Gewm, Potentilla, Rubus,
Rosa, and Sorbus are inexhaustible in the formation of hybrids. On the other
hand, the Papilionacex, a family allied to the Rosacex, is peculiarly wanting in
hybrids.

This discrepancy between nearly-related families in respect of the number of
their hybrids is again noticeable in the class of plants known as the Monopetale.
The Labiate, e.g. the genera Ajuga, Prunella, Calamintha, Lamium, Marrubium,
Mentha, Salvia, and Stachys include numbers of hybrids, whilst the Boraginacez
have very few. Of the latter only one or two hybrids are known, and these belong
to the genera Pulmonaria and Symphytwm. The Scrophulariacee and Rhinanthacez
have long been noted for the great variety of their hybrids; the genera Pedicularis
and Verbascum in particular exhibit a great wealth of forms, Pedicularis in alpine
regions and Verbascwm on the shores of the Mediterranean. Verbascwm alone
includes more than fifty. In the case of Gentianacez, also, the products of a great
number of different crosses are found in the Alps, the chief parent-species being the
long-stalked Gentiana lutea, G. Pannonica, G. punctata, and G. purpurea. Pri-
mulacesw, whether growing on the upper or the lower levels of mountains, are
famous for the abundance of their hybrids. In the genera Androsace, Primula,
and Soldanella the number of hybrids identified by Botanists surpasses the number
of the species from which they have sprung. The Ericacex, although comparatively
poorly represented in Europe, exhibit several hybrids derived from the genera Erica,
Rhododendron, and Vaccinium.

Hybrids are also specially numerous in the family of the Rubiacee, the genus
Galiwm being the most prolific in this respect. But the greatest number of all is
to be found amongst the Composite. More than two hundred hybrids have been
identified in the genera Achillea, Carduus, Centaurea, Cirsium, Hieraciwm, Inula,
and Lappa alone. Of hybrid Composite the following are particularly worthy of
notice: —Hrigeron Hiilsenii, which is the result of a cross between Hrigeron
Canadense, an annual species brought into Europe from America, and Hrigeron
acer, a perennial species indigenous to Europe, and, secondly, the Cudweed hybrids,
Filago miata, F. neglecta, F. subspicata, &c., which spring from crosses between
annual species, and are, therefore, exceptional, for annual species in general rarely
produce hybrids.

In many cases only a few individual instances of these natural hybrids have
been observed; in some, indeed, one single specimen alone has as yet been discovered.
The majority, however, grow by the hundred or by the thousand in the localities
proper to them, and many are represented by immense numbers of plants, and
possess a wide area of distribution. Salvia betonicifolia, a hybrid derived from
Salvia nemorosa and S. nutans, occurs as commonly as its progenitors in places on
the grassland in the central parts of Siebenbiirgen (Hungary); Marrubvum remotum,
a hybrid of Marrubiwm peregrinwm and M. vulgare, is to be found everywhere on
the pleins of South-Eastern Europe, especially in the flat country by the Theiss and

586 THE GENESIS OF NEW SPECIES.

the lower Danube; Roripa anceps, the hybrid of 2oripa amphibia and R. sylvestris,
is met with all over the district forming the basin of the Baltic; Promula digenea,
a hybrid derived from Primula vulgaris and P. elatior, grows in its thousands in
the upland meadows of the Eastern Alps; Betula alpestris, produced by the crossing
of Betula alba and B. nana, is met with in great abundance in the Jura, in Scandi-
navia, and in the North of Russia, and here and there entire copses are composed
of it; Nigritella suaveolens, a hybrid produced from Gymnadenia conopsea and
Nigritella nigra, is so common in the Central Alps, for instance, in the Pusterthal
of Tyrol, that hundreds of specimens are sometimes encountered in a single meadow;
Primula Salisburgensis, the hybrid of Primula glutinosa and P. minima, is repre-
sented by a host of plants on the Tyrolese Alps, as, for instance, on the Muttenjoch
and the neighbouring mountains which separate the Gschnitzthal from the Obern-
bergthal.

Several hundreds of other cases of the kind might be mentioned, but the limits
of this book will not allow me to do more than give the following names selected
from the long list that lies before me:

HYBRD. PARENTS.
Asplenium Germanicum.....ccccccere Asplenium Ruta-muraria x A, septentrionale.
Calamogrostis acutiflora.... C. arundinacea x C. epigetos.
Carex Benninghausiana.... C. paniculata x C. remota.
Scirpus Duvalit........c0008. S. lacustris x S. Pollichit.

TUncus AfUsuser.ccccccccccccceseccceees J. effusus x J. glaucus.

Orchis Dietrichiandu....ccceeecceees O. tridentata x O. ustulata.
Potamogeton spathulatys..........00+ P. polygonifolius x P. rufescens.
Populus CONESCENS......cccescccceecnere P. alba « P. tremula.

Salix Austriaca........cccceceeeccseeees S. grandifolia x 8. purpurea.
Rumer MARUMUS oo. ccieecccecceeereees R. aquaticus x R. Hydrolapathum
Polygonum Mite... ivcecccccereeeeees . PB. Hydropiper x P. Persicaria.
Cistus Florentinus ........cccceeceeceeee C. monspeliensis x C. salvifolius.
Drab, Hoppeandiscrcccccccccseveecceees D. Fladnizensis x D. Carinthiaca.
Roripa stenocarpa .........ceceeceeseees R. palustris x R. sylvestris.
Pulsatilla Hakelit........cccccceeeeee P. patens x P. pratensis.

Drosera Ob0vata...........cceceeeseneeees D.z longifolia x D. rotundifolia.
Epilobium salicifoliwm.........cccceces £. alsinifolium x E. montanum.
Sorbus latefolta, .....ecccccseseereerenees S. Aria x 8. torminalis.
Potentilla procumbens........0.0.ccee0 P. erecta x P. reptans.

Mentha nemor ose ....iecceccccccevses i. AL aquatica x M. sylvestris.
Pedicularis atrorubens......ccceeccceee P. incarnata x P. recutita.
Verbascum rubtginosum ..ecccccccveces V. Austriacum x V. pheniceum.
Acanthus spinulosus u...ccceecceceeee A. mollis x A. spinosissimus.
Gentiana Charpenttert..cccccccseave G. lutea x G. punctata.

Primula pubescens oo... eccecesevveees P. Auricula x P. hirsuta.
Vaccinium intermedium .......c.ccc00 V. Myrtillus x V. Vitis-idaea
Erica, Mach Qyt.....icccccccecccccccseeaee E. ciliaris x E. Tetralix.

Cirsium tatarieumrcccccccccccerccees C. canum x C. oleraceum.

Lappa pubens 0. ceccceeceseeeees L. minor x L. tomentosa.
Mieracium stoloniflorum.......ccccc... A. aurantiacum x H. piloselleforme.

The fact that hybrids exhibit every conceivable degree of frequency of occur-
rence might lead one to suppose that the rare hybrids were those that had been most
recently produced, and that they exist only as isolated plants because they k-ve not

PERMANENCE OF HYBRIDS. 587

yet had time to disperse and multiply. This conception would not, however, accord
with the actual condition of affairs. In point of fact, the floral contrivances which
exist for promoting crosses between different species occasion a constant origination
of hybrids, but it is certainly not the case that they all have the prospect of becom-
ing new species. Many are called, but few are chosen. In only a fraction of the
total number of fresh plant-forms produced yearly by inter-specific crosses do we
find the power to survive and multiply. The first condition that must be fulfilled if
a hybrid is to become a species is that it be fertile, ¢.e. that its flowers yield seeds
capable of germination as a consequence of fertilization with their own pollen. By
“their own pollen” is here meant not only that which is developed in the same
flower as the stigma which receives it, or in some flower on the same plant, but also
pollen belonging to other plants provided they belong to the same hybrid-formation.
To this condition another is added in the case of dicecious, pseudo-hermaphrodite,.
and completely dichogamous flowers, viz.: that several individuals of the hybrid
must make their appearance at the same time, and that of these at least one must
bear male flowers and one female flowers. If we suppose the case of a Willow
hybrid, of which all the individual-plants bear catkins of male flowers only,.
obviously no propagation by means of fruits is possible. If none but female flowers
are borne, these may be crossed with the parent-species and give rise to goneoclinic
hybrids (cf. p. 559), and perhaps, in addition, ternary hybrids may be produced, but
no unmodified descendants can be expected from the fruits of a Willow of the kind.
The same thing applies in the case of Cirsvwm, the separate individuals of this genus
being differentiated into those bearing pseudo-hermaphrodite male flowers and those
bearing pseudo-hermaphrodite female flowers (see p. 294). This affords sufficient
explanation of the fact that although Willows and Cirsiums are continually develop-
ing numberless hybrids, few instances are known which one can affirm to be the
beginnings of new species. It usually happens, in fact, in the case of these hybrids,
that all the plants which arise together at a particular spot are furnished exclusively
either with true or pseudo-hermaphrodite male flowers, or else with true or pseudo-
hermaphrodite female flowers. The goneoclinic hybrids produced from the latter
are for the most part represented by greater numbers of individuals. Moreover,
amongst those individuals both sexes much more frequently make their appearance;
hence, they have a far better prospect of being preserved.

The development of a hybrid into a species is also dependent on the conditions.
determined by the habitat. When a species thrives well at a particular place, is
represented by a large number of individual plants, and renews itself in descendants
which are in the main unchanged, it may be assumed that the organization of that
species is suited to the soil and climate of the habitat in question. If there were no
such harmonious relation there could be no question of the species flourishing, but
on the contrary is would sooner or later die out. This suitability of the climate and
soil to the organization manifested in the plant’s external form must also exist in
the case of the newly developed hybrid if the few individuals which spring up at
any particular place are to survive in their original settlements, and to give rise to

588 THE GENESIS OF NEW SPECIES.

a numerous progeny. Sometimes such suitability does exist, but sometimes also it
does not. In the latter case the hybrid is suppressed as soon as it sees the light.
But even if its organization is adapted to the soil and climate of the place of origin,
it has to enter upon a struggle with the species already established there, and
especially with its own parent-species. If the latter grow luxuriantly and in large
numbers at the spot, it is not easy for the new form to take possession of the
ground, In two cases only is there any prospect of the place of origin becoming a
permanent home for the hybrid’s descendants: firstly, where the hybrid, in virtue
of its particular attributes, is equally well, or perhaps even better adapted to the
habitat of the parent-species than are the plants already established there, and
secondly, when the hybrid originates at a spot more or less removed from the place
where the parent-species grow and encounters conditions of soil and climate which
agree with it better than with the parent-species.

That these conditions of the origin of species from hybrids are sometimes
fulfilled will now be shown by a few examples. In the Tyrolese Alps, to the
south of Innsbruck, at the head of the valleys known as the Stubaithal and the
Gschnitzthal, there are certain mountains which rise steeply to a height of from
2500 to 3000 metres. The base of these mountains is composed of crystalline
schist; midway up their ascent mixed strata of schist and limestone are encoun-
tered; and above these strata there is limestone and also dolomite, rising abruptly
and forming the peaks and ridges. Half-way up the sides, where the soil exhibits
great variety, an extraordinarily rich flora is developed. Plants which are, except
in this instance, peculiar to schist formations, and others usually only found on
limestone, here grow close together. Amongst other species the Alpine Roses,
Rhododendron ferrugineum and R. hirsutum, grow side by side on the same soil
and on the same slopes. Associated with them is a third species of Alpine Rose,
Rhododendron intermedium, which has sprung from the crossing of R. ferru-
gineum and R. hirsutwm. At several places, eg. on the eastern and northern
slopes of the Hohe Burgstall, in the Stubaithal, and on the Padaster Alp in the |
Gschnitzthal, Rhododendron intermediwm occurs more commonly than either of
the parent-species. Like the latter, it grows on soil rich in humus, flowers
abundantly, develops fruits with fertile seeds, and transmits its characteristics
unaltered to its descendants. Here and there isolated plants are found which must
be ranked as goneoclinic hybrids, but plants of Rhododendron intermedium form
the larger proportion of the Alpine Roses which clothe the mountain-sides. This
form accords in every particular with the requirements demanded of a species, and
is quite as much a systematic entity as either R. serruginewm or R. hirsutum.
The following is the explanation of how this has come to pass: The colour of the
flowers is a little lighter than in R. ferruginewm and richer than in R. hirsutum;
it is a brilliant carmine tint, and enables one even at a distance to identify every
plant of the hybrid. Hive- and bumble-bees hovering about in search of honey
are more attracted by flowers of R. intermediwm than by the others, owing to
the superior brilliancy of their coloration, and the result is that these flowers are

INSTANCES OF SUCCESSFUL HYBRIDS, 589:

erossed with pollen of their own kind. If no insects appear upon the scene, auto-
gamy takes place. In either case fertile seeds are developed, and give rise to plants
which do not differ from the parent-form. In places where detritus from the
adjacent limestone and dolomitie cliffs is mixed with the humus of the soil the
seedlings thrive distinctly better than those of R. ferruginewm and no less well
than those of R. hirsutum. Thus, so far as the soil is concerned, R. intermedium
has an advantage over R. ferruginewm, and in respect of insect-visits it is better
off than either of the parent-species. These advantages, though apparently insig-
nificant, are not merely sufficient to prevent R. intermediwm from yielding to the
parent-species in the struggle for existence at the places in question, but even give
it rather a better chance of prevailing.

As a second instance, we will take Salvia sylvestris, the hybrid offspring of
Salvia nemorosa and Salvia pratensis. This plant grows in dry meadows all over
the low country to the south of Vienna, as, for instance, on the banks of the river
Leitha, which separates Austria proper from Hungary. The landscape there is
slightly undulating, the elevations are composed of boulders and clay, and wherever
the latter is present in great quantities, especially on the gentle slopes of the rising
ground, Salvia nemorosa constitutes an important item in the vegetation. The
hollows are full of a dark moist earth, with a rich admixture of humus, and there
we find meadows in which Salvia pratensis grows luxuriantly. These two kinds.
of habitat usually pass quite gradually into one another, and the parts common to
both consist of dry meadow-lands. Salvia nemorosa does not thrive in the intri-
cate grass-carpet of these meadows, and is rarely to be seen there, whilst for Salvia
pratensis the soil is too dry, so that that species also is but poorly represented on
the areas in question. On the other hand, these dry meadows are the most suitable
ground for the hybrid Salvia sylvestris, and it thrives exceedingly upon them.
Its flowers are much visited by insects; its fruits ripen in as large numbers as
in the case of S. nemorosa or S. pratensis, and have been found by experiment to
be fertile in a proportion of more than 60 per cent. Salvia sylvestris has
therefore scattered itself all over this dry meadow-land, and manifests all the
characteristics essential to our conception of a species.

A third example is Nuphar intermedium, a hybrid derived from Nuphar
lutewm and Nuphar pumilum. This plant grows in lakes in the Black Forest
‘and in the Vosges. It is also scattered over North Germany, and occurs with
increasing frequency in Central and Northern Russia and in Sweden. It has been
found as far north as Lapland. At the northern extremity of this large area of
distribution Nuphar intermediwm is more abundant than the species from which
it is derived; indeed in many places it occurs in their absence, and in fact passes
beyond the northern limits of their area of distribution. In these situations there
is, of course, no possibility of the hybrid’s crossing with either of the parent-
species or of the formation of goneoclinic hybrids. Nuphar intermediwm subsists
independently there, multiplies without change of form, and has in fact established
itself as a species. This phenomenon is explained as follows: The northern limit of

590 THE GENESIS OF NEW SPECIES.

the distribution of each of the three Water-lilies in question is determined by their
not being able to ripen fruits beyond that limit. Of the three, Nuphar lutewm flowers
the latest, and therefore its fruits are also the latest to ripen, whence it follows
that it is the first to fall behind; that is to say, it reaches the northern limit of
distribution sooner than the others, and ceases to ripen fruit in regions where the
others are still able to do so. But Nuphar pumilum and N. intermediwm are also
different from one another in this respect. In Norbotten and Lapland Nuphar
intermedium ripens its fruits a little earlier than NV. pumilum, and it is conse-
-quently able to extend rather further north than NV. pumilum. The further north
plants go, the shorter becomes the time allotted for the performance of their annual
work; and those which ripen their fruits early have a great advantage over those
which ripen later. Concerning Nuphar intermedium, it has also been ascertained
that the individual plants produced in nature are more fruitful than those
reared in gardens from artificial crosses. In the case of plants obtained in this
manner in the Botanic Gardens at Kénigsherg each capsule contained from 15 to
18 fertile seeds, whilst capsules ripened in the small lakes of the Black Forest
contained from 38 to 63, and others taken from plants growing in Lapland con-
tained from 41 to 72 such seeds. From these data we may infer, in the first place,
that WV. intermediwm is most prolific in situations beyond the range of the parent-
Species; and, secondly, that it would be wrong to suppose that because a hybrid
may be comparatively infertile or actually sterile in a particular locality, such
infertility is a characteristic of the plant wherever it may occur.

As may be gathered from the above account of these three examples, the advan-
tage which a hybrid may possess over the parent-species, whereby it is enabled
to subsist and multiply side by side with those species, is not always of the same
kind. In one case it is the more vivid coloration of the flowers, in another the fact
of the hybrid being better adapted to a particular state of the ground, whilst in
the third the earlier ripening of the fruits, which enables the hybrid to stand a
more rigorous climate, gives the requisite advantage. These do not, of course,
exhaust, by a long way, the possible sources of superiority, and there are many
instances of hybrids which thrive better than the parent-species when the climate
becomes milder, moister, or drier, as the case may be. It is obvious that of all the
different advantages which may come into play those connected with climatic con-
ditions are the most important, and the genesis of hybrids is probably most fre-
quently due to the operation of this kind of advantage.

Far too little significance has been attached to the fact that the greater number
of hybrids are not found in districts where the parent-species grow together with
equal luxuriance, but occur where one or other of those species is meagrely repre-
sented, owing to the climate not being favourable to its distribution, Again, large
numbers of hybrids are found in parts where the boundaries of several species
coincide. In Europe such regions exist in the strips of land where the advance-
posts of the Floras of the Baltic and Black Sea, and the Floras of the Baltic and
the Mediterranean, respectively, encounter one another, and particularly in the

acacia

THE DISTRIBUTION OF HYBRIDS. 591

lower limits of the Alpine Flora. Another characteristic of these borderlands is
the fact that the separate hybrids growing on them are almost always represented
by a large number of individuals, and the consequence is that there is no great
chance of their crossing with the parent-species and gradually reverting, in succes-
sive generations, to those species. If isolated individuals belonging to a particular
hybrid grow in the midst of thousands of plants of the parent-stocks, their stigmas
will, in all probability, be dusted with pollen from the latter species. This proba-
bility diminishes, however, as the number of individuals of the parent-species
flowering in the same locality as the hybrid diminishes; if that number is small
the hybrid is thrown mainly upon its own resources for fertilization, and, provided
it is self-fertile, there is nothing to prevent its multiplying and becoming dispersed. .

Connected with the above is the further fact that in the neighbourhood of a
hybrid which has become a species there is sometimes no trace of one of the parent-
species, it having completely died out. The slightest change in climatic conditions
may cause the plants of a particular stock to succumb at the confines of the stock’s
area of distribution, where they are only present in small numbers, and are anything
but strong; and when this happens we find the other parent-species alone growing
side by side with the hybrid, and even that species is possibly not so well adapted
as the hybrid to the altered conditions. Of cases in point we will select two from
the East of Europe and two from the West.

When Epilobium alsinefoliwm and Epilobiwm palustre are crossed a hybrid is
obtained which, when fertilized with its own pollen, yields a large quantity of fertile
seeds. The plants reared from these seeds exhibit the same characteristics as
the plant from which the seeds were taken. This hybrid grows together with
the parent-species in the Riesengebirge, and has received the name of Hpilobvum
scaturiginum. It is likewise a native of the Bihar Gebirge, on the confines of
Hungary and Transylvania, and is of very common occurrence in the springs and
rivulets in the vicinity of the Hochkamm (a mountain of this chain). Yet, of the
two parent-species, only one, viz. Hpilobium palustre, grows amongst these moun-
tains. Again, Prunella hybrida is a hybrid springing from Prunella laciniata
and Prunella vulgaris. It is widely distributed in the Wienerwald district, and in
some places is commoner than the parent-species, whilst in Moravia and Bohemia it
occurs in places where one of the latter, viz. Prunella lacvniata, is entirely absent.
A third instance is afforded by Primula brevistyla, called also Primula variabilis,
a hybrid derived from Primula vulgaris and P. officinalis. This plant is true to
seed, and is met with everywhere throughout almost the whole of Europe in
company with both parent-species. In some districts of France it is found also in
places where one or other of the latter species does not grow at all, and even where
both are absent. Our fourth example, Linaria stricta, is the hybrid of Linaria
striata and Linaria vulgaris. It occurs in many places in the West of Europe,
together with its progenitors, but in the South of France, in the neighbourhood of
Montpellier, it is found growing with Linaria striata alone, whilst the other parent-
‘ stock, LZ. vulgaris, is never found in the district.

592 THE GENESIS OF NEW SPECIES.

We shall have another opportunity of describing the way in which the lines of
demarcation of the ranges of entire floras become displaced in consequence of the
changes which the climate of a region is liable to undergo in course of time. These
displacements of floral regions are, as a rule, the result of very slow and inconspicu-
ous migrations on the part of the plants constituting the floras in question. The
direction of migration is invariably towards the places whose climatic conditions
agree best with the organization of the plants, and is, in the case of any one species,
either an advance or a retreat, according to the nature of the circumstances which
impel the species to migrate. The different plants of a flora do not all migrate in
a host together. Some species abandon their former home entirely and establish
themselves in a new locality more or less remote from it; others leave a few of
their kind behind in the old settlement at isolated spots which happen to be in
peculiarly favourable situations, and many succumb to the effects of the new con-
ditions or to the hardships incidental to the migration, and so die out. These
changes in the range of floras are naturally accompanied by all sorts of alterations
in the social relationships of the plants concerned especially with regard to the
co-existence of hybrids and their progenitors. It may happen that one or both
parent-species are left behind, whilst the hybrid advances, or the hybrid may
remain behind, whilst one of the parent-species advances; or, again, one of the
parent-stocks or both may die out. The facts concerning these local displacements
explain the phenomenon that species which, from their characteristics, may be
looked upon as hybrids of two other species, oocupy in each case a district which
is separated, and often at a considerable distance, from the areas inhabited by the
species supposed to be their progenitors. The characteristics of the kind of Sorrel
named Rwmesx Patientia lead one to the conclusion that it is a hybrid derived from
Rumen aquaticus and Rumex crispus. It is found, however, growing wild in
Hungary and in Bosnia in parts where neither Rumex aquaticus nor R. crispus
oceurs at all. In Herzegovina there grows fairly commonly a Micromeria which
has been named by one of my friends Micromeria Kerneri. So far as its charac-
teristics are concerned it must be considered to be a hybrid of Micromeria greca
and Micromeria Juliana; yet neither of these two species grows in Herzegovina at
the present time, and they are not met with at any nearer spot than the part of
Dalmatia which stretches westward from Herzegovina, and belongs to the area of
distribution of the Mediterranean flora. In the little upland valleys of Planail and
Plawen, which run down from the mountains of the Oetzthal into the valley of the
Adige, there grows a Pulsatilla named Putsatilla nutans. If it occurred in company
with Pulsatile vulgaris and Pulsatilla montana, all Botanists would be unanimous
in looking upon it as the product of a cross between those two species. Yet Pulsa-
tila Calgaran and P. montana do not grow in the high valleys in question, but are
first met with Bt a distance of many miles from them, the former in the Unterinnthal
and the latter in the Vintschgau (a portion of the Adige valley).

Inasmuch as the last-mentioned cases have to do with processes which have
taken place long ago they partly belong to the next chapter, where the genesis of

THE GENESIS OF NEW SPECIES. 593

species in the past will be discussed. They here bring to a natural conclusion a.
series of examples adduced to show in what manner a genesis of new species may
ensue in the present, and may have taken place in the past. No sharp line of
demarcation is to be found between different epochs in this connection any more
than in the case of any of the other phenomena which, in the aggregate, constitute.
the history of species.

Now that it has been shown how new species arise from hybrids, or, in other
words, from the crossing of species in pairs, the question presents itself whether, in
addition to this one method, there are not also others leading to the same result.
In answering this question we must bear in mind that every permanent change in
external form which is inherited by a plant’s descendants must be preceded by a
change in the constitution of the protoplasm, and that so far as investigation has.
elicited the facts, the centre of the change is located exclusively in a particular.
protoplast which lies hidden in the ovary and there receives the spermatoplasm.
The stimulus which causes the change in this protoplast can only proceed from the
spermatoplasm, and every speculation concerning the formation of new species must.
therefore be associated with the question whether in the intercrossing of plants of
one species and in autogamy the protoplasm in the course of its journey to the
ooplasm may, as a result of its exposure to new external conditions, undergo modi-
fications of so fundamental a kind that its influence on the ooplasm is subject to:
corresponding variations. In the first place, it might be imagined that the pollinated
stigmas do not always act in the same way upon the spermatoplasm of the pollen-
cell. Reference has already been made to the fact that a stigma may sometimes be
almost simultaneously dusted with the pollen of very different plants (see p. 404),
but that it has the power of exercising a selection, and that in every case only one
kind of pollen is induced to put forth tubes by which a real fertilization is accom-
plished. The other kinds of pollen upon the stigma are not known to have a direct.
effect upon the ovule. But that there is some interaction between them and the
protoplasm in the cells of the stigma is evidenced by the fact that they swell up:
wherever they are in contact, and (as has been shown, p. 414) are frequently found
developing pollen-tubes. Now it is possible that the reciprocal action of the contents.
of these pollen-cells and the contents of the stigmatic cells may produce some change
in the latter, which is transmitted to the contents of those other pollen-tubes which
are to enter into combination with the ooplasm. Such modification might conceiv-
ably affect the nature of the stimulus imparted to the ooplasm, and this alteration
in the stimulus might be manifested in a change in the form of the individual
arising from the fertilized ooplasm. The likelihood of all these possibilities and
assumptions being satisfied is extremely small, but as no researches have yet been
instituted into the matter, it cannot be dismissed with an unconditional negative.

In artificial crosses between different species of Cirstwm it has often been noticed
that pollen-cells taken from a single capitulum vary in their effects upon the stigmas.
of a second capitulum, inasmuch as the seeds produced by the different florets,

though all fertilized with the same kind of pollen, yield dissimilar plants when
Vou. II. 88

594 THE GENESIS OF NEW SPECIES.

they germinate. The variation is limited, it is true, to the different degrees in
which the seedlings resemble one or other of the parent-plants. If the cross is
between two plants of the same species no such variation can occur, seeing that the
plants crossed are alike in form. But there is still the question whether differences
in the age, size, and luxuriance of growth of the individuals which cross may not
have some influence on the result. So far as my experiments show, these differences
have no effect on the genesis of new forms, and have no prospect of becoming per-
manent characters in the offspring. A poor stunted plant growing on dry soil may
produce seeds which, on being planted in a good moist soil give rise, under favour-
able conditions, to well-developed plants capable of flowering luxuriantly. As is
well known, the first flowers of an inflorescence are always much larger than those
which subsequently open at the apices of the spike or raceme, or on the ultimate
ramifications of the cyme as the case may be. Now, if the large earliest flowers
are crossed one with another, and likewise the small latest flowers, and the seeds so
obtained in each case are kept separate but reared under similar conditions, the
plants produced from them do not differ in the slightest degree from one another,
but in their turn bear flowers, of which the first are the largest and the last the
smallest. Notwithstanding these results, however, I should not like, without
further investigation, to deny the possibility of the specific constitution of the
spermatoplasm undergoing some change as a result of external influences in the
course of its development, whether during its imprisonment in anthers or antheridia
or on its way to the ooplasm, or to say such change might not cause the descendants
of the plants concerned to differ in form from the individual from which they
sprang.

It has been established beyond all doubt that modifications of form directly
induced by conditions of soil or climate are not hereditary, and that every change
of form which persists in the descendants is only brought about as the result of a
process of fertilization, or, in other words, that new species can only arise through
fertilization. Herein lies also the solution of the marvellous phenomenon known as
the alternation of generations, and of the question why plants in general flower and
undergo fertilization. To these processes is due the genesis of new species. The
propagation of plants, their multiplication and dispersal, may also be effected by
means of brood-bodies, and as a matter of fact these processes are ‘continuously
operating on a vast scale. But the plants reproduced by brood-bodies retain the
form of their ancestors unaltered, and no new forms arise in this way. Suppose
that a locality is occupied exclusively by plants which multiply by brood-bodies
only and do not change their form, and that in consequence of a change in the
climate such species as are not adapted to the new conditions abandon their homes,
or else languish and die out, the probability is that many of the vacated spots will
remain unoccupied owing to there being no recruits in the neighbourhood, or from
out its confines, that are better adapted to the new conditions. If, on the other
hand, the area in question is inhabited by plants which reproduce sexually and
which, by crossing one with another, produce descendants of diverse forms, there is

DERIVATION OF EXISTING SPECIES, 595

every probability that amongst the assemblage of new forms some will be better
adapted to the new conditions when a change of climate occurs than those of the old
species which are driven out thereby, and that these new forms will therefore be
able to take the place of the latter.

It is only from this standpoint that we can properly understand the phenomena
of the alternation of generations, the separation of the sexes, dichogamy, and all
the rest of the wonderful floral contrivances, the object of which is to facilitate the
crossing of two species during the first stage of flowering and only to allow of
crossing between plants of one species, or of geitonogamy, autogamy, or cleisto-
gamy in the event of no inter-specific crossing taking place. As a result of these
contrivances, numberless new forms are continually being generated which are
respectively adapted to all the most various conditions of soil and climate. So
long as no change in climatic conditions takes place, the majority of these forms
have very little chance of surviving and of naturalizing themselves as species
-amongst the plants already established in the same locality. But when, in conse-
quence of a change of climate, the ranks of the species in possession of the ground
are thinned through ‘the abdication of many of those best adapted to the condi-
tions of life previously existing, the real significance of the new forms which have
arisen as a result of the sexual process is manifested in the fact of those which are
best adapted to the new conditions taking possession of the spots vacated and
settling down there as new species.

DERIVATION OF EXISTING SPECIES.

The plants preserved as fossils in former ages are not only the forerunners
but the ancestors of the existing vegetation of to-day. There was no general
rejuvenescence and extinction of organisms coincident with the beginning and end
of the several “periods” of the history of the earth, The changes in the organic
world, like those in the inorganic crust of the earth, were accomplished gradually by
slow degrees, and the organisms of the present day are a continuation of, and have
been slowly evolved from, those of former ages.

So far, there is little difference of opinion amongst naturalists; but as to the
causes of the differences in form between the vegetation of the present and the past,
the most various theories are held. Nor is this surprising, seeing how largely our
conclusions are based on conjectures. And when the flood-gates of speculation are
rolled back it is not always that the proven is clearly distinguished from the
unproven. An import is attached to isolated facts which they do not merit, and—
most mischievous of all—the existence of wide lacune in our knowledge is con-
cealed, or these lacunz are dexterously bridged over with unmeaning, high-sounding
words and hollow phrases which, while astonishing us for the moment, leave us
chastened and confounded. The confirmed mistrust aroused by these extravagances
which obtains concerning all that bears on the derivation of species demands that
we should devote a brief consideration to the prevailing theories, and especially to

596 DERIVATION OF EXISTING SPECIES,

such as bear upon the conversion of species of former times into those of the exist-
ing vegetation.

A change in the conditions of life has, according to a widely-spread view, been
the immediate cause of a change in-the vegetation. The altered conditions of life
provoke new wants in the plant, and these new requirements have led to a trans-
formation of their organs. Stimulated by use, the organs in question become
enlarged and further developed; others, no longer of service, become smaller,
atrophy, and disappear. It is the cumulative result of these small and almost
imperceptible changes that in course of time becomes apparent. These structural
changes are transmitted to the progeny, and with an increasing tenacity, the
greater the number of generations which have been exposed to the altered condi-
tions. This, the theory of adaptations, has provoked wide discussion and criticism.
It is urged against it that, whether wild or cultivated plants be considered, it is
only isolated or a few individuals, never the whole of the members of a species,
which exhibit these variations and transmit them to their offspring. If these new

characters are immediately due to the soil or climate, then all the individuals of a - -

species, exposed to like conditions of growth (environment), should exhibit them
and hand them on to their offspring. The permanence of the influence—and to
this many naturalists and others attach great importance—is without significance
in this matter. When a change is called forth—be it by an altered source of
nourishment, by the influence of heat or cold, light or darkness, moisture or dry-
ness—it must become apparent upon the growing plant, since a change in the plant
stands to a change in the environment as effect to cause. If the cause ceases, so
also does the effect, equally after the lapse of a year or a hundred years. But a
much more potent criticism of the theory of adaptation is the result of a series
of experiments which were carried out for the solution of these questions. From
them we see that an altered environment calls forth certain changes in the plants
submitted to it, but that these are not transmitted to the offspring, are not heredi-
tary, and that the influences of soil and climate do not provoke a fundamental
change in the constitution of the protoplasm. Influences of this sort can induce a
diseased condition in a plant and can even kill it, but they cannot bring about a
change which can be transmitted to the next generation. Though soil and climate
play a most important part in the struggle of species and varieties for existence,
and though the environment has a great influence on the origin of varieties and on
the distribution and migration of plants—as the immediate stimulus to the origin
of new and transmissible characters, and thus to the modification of species, change
of environment is without significance.

Another theory dealing with the origin and modification of species is that
known as the theory of progressive transformation by inherent forces. According
to it, the impulse to change resides in the inherent tendency of all species to
perfect themselves. This theory transcends all experience and depends on premises
and draws conclusions essentially metaphysical in nature; it deals only in part
with the results of scientific observation. It presupposes a creation of living

VARIOUS THEORIES, : 597

protoplasts endowed with the capacity to alter their constitution on their own
initiative; and, further, that these alterations take place along predetermined lines
in 4 direction leading from a lower to a higher platform; consequently the
imperfect organism necessarily, in course of time, passes over into a highly
developed, perfect one. Against this theory the following may be urged: The
first assumption involves creation. The question is: Is it possible for a living
protoplast to be formed from inorganic matter without the co-operation of already
existing living beings? The question obviously concerns the present and future
as well as the past, for what has happened once may again take place, for the
forces of nature, according to the laws of the conservation of matter and energy,
remain the same for all time. The discussion of this question resolves itself into
this: whether a little bit of protoplasm can arise from inorganic matter, and after
its origin can acquire the capacity of growing by the absorption of food from its
environment, &c.; in a word, whether it can exhibit those changes and movements
which we term life. When first organic compounds (formic acid, urea, sugar, &c.)
were synthesized in chemical laboratories from inorganic substances like ammonia,
carbonic acid, and water—compounds which formerly had only been produced as a
result of the activity of living protoplasm—naturalists began to think that these
things might take place in nature independent of already existing plants. It
seemed possible that these substances might, under the uncontrolled forces of
nature, unite and arrange themselves in the same manner as occurs within a
vegetable cell. The tendency of matter to combine, which plays so important
a part in nature, was pointed out, and especially the similarity between the
structure of crystals and that of certain cells; the properties of finely-divided
soil also were called to mind, how it absorbed gases, took up water in varying
quantities, altered salt-solutions, separating certain of their constituents, and what
was especially noteworthy, increased the capacity of many simple substances to
combine. This was at a time when chief importance was attached to the chemical
properties of protoplasm; it was thought that, once given the substance, it would
form itself into cells like crystals. Of the ultimate structure of protoplasm and
of the nucleus knowledge was as yet very incomplete. The tendency of that time
was to explain all those phenomena which constitute life as,the resultant of the
various forces which form inorganic bodies, and to deny the existence of any wide
gulf between the living and non-living world.

The experiments to produce living matter had all of them negative results.
But this of course is no proof of its impossibility; for it can always be urged that
wrong methods were followed, and improper conditions imposed. Nor, on the
other hand, does it follow from the fact that hitherto living matter has never
been known to originate independently of existing organisms, that its production
is impossible. Since we cannot arrive at definite results by experiment, the in-
vestigator must depend on other considerations.

The second assumption of the theory of transformation from internal causes,
that plants have the inherent capacity to modify their internal constitution and,

598 DERIVATION OF EXISTING SPECIES.

similarly, their external form spontaneously, has been so fully met by the obser-
vations recorded in the last chapter that it is hardly necessary to deal with it
now at great length. I shall content myself with pointing out that it is impossible
to give a natural explanation of such a phenomenon. Every variation presupposes
a corresponding disturbance; for the acquirement of any new structural character
the plan of construction must undergo some fundamental alteration. The naturalist
is unable to grapple with the phrases “internal causes”, “internal force”, “force
of transformation”, “tendency to differentiate”, “principle of progressive trans-
formation”, when attempting to explain variation in a natural manner upon
mechanical principles. Nor is the likening of this transformation to the meta-
morphosis which every individual passes through at various periods of its existence
at all to the point, since metamorphosis repeats itself with great constancy in
every species according to the plan of construction which is laid down in the
specific constitution of the protoplasm. That the protoplasm of any species should,
in the absence of any impulse or stimulus from outside, be able spontaneously to
alter its plan of construction contradicts all our experience of the normal action
of natural forces. Even should we conceive vital force, the dormant energy of
the protoplasm, to be converted into an active form, it could only give rise to
movements which have their origin in the specific constitution of the protoplasm.
And now we come to the assumption that this inherent force of transformation
is a progressive one, that it leads to a higher or more perfect development. But
what is to be regarded as a higher development amongst plants? A tree with
its brightly coloured flowers and luscious fruits seems more highly developed to
the non-botanist than a low herb with inconspicuous flowers, or than the green
filaments of a Spirogyra destitute of flowers. The supporters of the theory under
discussion assert that the highest development is that which exhibits the greatest
complexity of form, and in which division of labour is carried furthest. And in
this assertion they do not essentially differ from the popular view. Complexity
of form and division of labour are undoubtedly carried further in an Apple-tree
than in the Spirogyra of the ponds and ditches. But it must not be forgotten
that the differentiation of a plant-body into various tissues, the production of
wood, bast, and cork in its stem, of cuticle, stomates, and hairs on its leaves, of
various colouring-matters and aromatic substances in its petals, and of sweet juices
in its fruits, stands in harmonious relation to the environment of the plant in
question. Change the conditions, and imagine the Apple-tree submerged in a pond;
it is no longer in harmony with its surroundings, its complexity of tissues, its
wood, stomates, &., are not so well adapted for these conditions as are the Spiro-
gyras and Water-weeds equipped with organs of another type. The size of a
plant is often—in the popular estimate—the indication of its high organization.
A big plant gives the impression of possessing a more perfect development than
a small one. But this criterion leads to no satisfactory result; it is sufficient to
instance the case of certain huge sea-weeds (Macrocystis) of the southern seas, which
exceed our greatest forest trees in height. Many Thallophytes, only visible under

VARIOUS THEORIES. 599

the microscope, show a greater complexity of structure of their constituent cells
than do many Flowering Plants; and, should especial importance be attached to this
character, Diatoms and Desmids must be regarded as more highly organized than
many small annual Composites. The idea of progressive development implies a
recognition of that species of plant which is most highly developed and which
stands upon the apex of the pyramid, or, at any rate, of the group of plants which
has already reached the furthest point—is it the Aristolochiaces, Cannacex, Mag-
noliacex, the Orchids, the Composites, the Ranunculacezx, the Papilionacex, or the
Pomegranates? Any one who has studied carefully the structure of these plants
knows well that it is impossible to make an estimate of this kind. In a book
of Botany one group must be treated first and another last, but this does not
necessarily imply that the last is the most highly developed; indeed the various
writers of systematic works begin and end with the most various groups. Like the
theory of adaptability, that of progressive transformations from inherent forces fails
to give us a reasonable explanation of the variations which plants have undergone
in process of time.

A third theory, based on the observations of modern times, is as follows: That
variations of form in the offspring arise through crossing, from the union of two
dissimilar protoplasts. This theory, based on the union of unlike forms, has been
fully sketched out in the last chapter. It assumes the existence in former times of
a vegetation rich in forms—an assumption amply justified by the fossil remains
which have been preserved. New forms arose, not by a progressive development
such as has been alluded to, but by a transformation or metamorphosis of those
already in existence. It was from the union of existent types that incipient new
species were produced. By the periodic recurrence of changes in climatic con-
ditions the areas of plant-distribution have received continual displacements, and it
was then that these incipient species or varieties were put to the test. Those well-
suited to the fresh conditions settled down into new species. They replaced their
less well-adapted ancestors in the plant-community, and they played the same part
as these had formerly done. A change indeed is brought about; but not (on the
lines of the theory of adaptability) as a direct result of climatic influences, nor from
an inherent tendency to progressive development. It arises rather from a change
in the specific constitution of the protoplasm in consequence of the crossing of
unlike forms. In basing the transformation of species on a crossing of this nature
we are relieved the necessity of picturing lacunz in a vegetation as a result of
climatic changes, or of any serious disturbance of the inter-relations of its various
component forms. Bacteria and Moulds, Mosses and Lichens, Ferns, Grasses, Palms,
and Coniferous Trees, have all of them a special function to fulfil in the great
community of plants, and they are to a certain degree dependent on one another.
Were one removed the whole would be affected, and it might well happen, did a
given group come to speedy extinction, that the whole community of plants might
suffer. But in every group at all times and in all places a reserve of new forms
continually arises by crossing, so that this danger is averted. With climatic

600 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

changes, of the older, less fit forms some are extinguished, whilst young, new
forms step into their places. Thus we see also that the conversion of Mosses
into Ferns, of Ferns into Conifers, and of Grasses into Pinks, &c., as assumed
by the theory of progressive transformation, would be a positive disadvantage
to plants as a community, and that its tendency would be in the direction of
anything but real progress.

It is important to recognize the fact that in the production of new forms by
crossing, it is not especially such forms as are constituted to resist an anticipated
change of climate that are produced. Of the forms which arise, some are fitted
for a more inhospitable, others for a milder climate; but it cannot be said of any
that they possess an assured future. Such only are able to maintain, propagate,
and establish themselves, as are from their internal organization and external form
in harmony with the prevailing climatic conditions of the moment. Those so
constituted that they are unable to thrive under the given external conditions
linger and become extinct; they are outstripped and overgrown by such as find
the environment to their liking. Hence we speak of the struggle for existence.
Plants in harmony with their surroundings are the victors, and they establish
themselves upon the arena of this encounter. This, briefly, is Darwin’s theory of
Natural Selection, a theory which marks an advance upon all other theories of the
origin of new species. Though many views may be held as to the precise manner
of origin and transformation of forms, there can be no difference of opinion as to
the significance of the struggle for existence and of the survival in this struggle
of those forms best fitted by their organization to the circumstances of the environ-
ment.

THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

The fact that the savants of ancient times made no attempt to classify plants
according to their structural characters is explained by their limited botanical
knowledge. Their interest was restricted to such plants as were in use as drugs,
poisons, and charms, to vegetables, fruits, and cereals, finally, to such as were
of value for decorative purposes and as symbols of religious observances. Nor
was the number of these plants considerable. Some five hundred forms were
known to Theophrastus (800 B.c.), whilst Pliny (23-79 .p.) records about twice that
number. The characters of these few plants could be retained in the memory
for the purposes of comparative investigations, and their recognition depended in
large part upon the general impression gained in the ordinary intercourse with
nature. Enumerations of plants were based far more on their medicinal or
economic uses, on their hurtfulness and beneficence for mankind, than on any
structural characters they might possess in common. Even in the herbals of the
sixteenth century, containing, as they did, new descriptions and incomparable
woodcuts, were the medicinal and economic properties of the various plants still

especially emphasized; Botany was still almost exclusively the handmaiden of
medicine and agriculture.

OLDER SYSTEMS OF CLASSIFICATION, 601

The first botanical writer to break with these old traditions was Clusius
(1526-1609); he described plants as he observed them, quite apart from their
value to man. Clusius, though a Belgian, spent many years of his life at Vienna,
and thoroughly explored the Flora of Austro-Hungary; previously he had investi-
gated the plants of Spain and Portugal. To England he paid more than one
visit, and received many exotic plants from Sir Francis Drake, the voyager. In
his Rariorwm Plantarum Historia, published originally in 1576, we find the
first attempt to classify plants according to their similar characters. In separate
books he deals with trees, shrubs, and under-shrubs, bulbous plants, sweet-smelling
flowers, scentless flowers, poisonous, narcotic, and acrid plants, with plants having a
milky juice, and with Umbellifers, Ferns, Grasses, Leguminose, and certain Crypto-
gamic plants. In those days some 4000 plants were distinguished by Botanists,
and the want of some system of classification was gradually felt. The groups
of Clusius and his contemporaries were inadequate, and the system of Cesalpino
(1519-1603), published in the first book of his De Plantis Libri XVI (1583),
failed to obtain the recognition it undoubtedly deserved—perhaps because it
was only sketched out in outline and lacked a full and detailed rendering.
Cesalpino was the first to convert observation into real scientific research; he
drew attention to the more hidden organs of plants, to the position of the seeds,
the number and mode of insertion of the cotyledons, &c., to the presence or absence
of flowers.

It is to Tournefort (1656-1708), a Frenchman, that we owe the first complete
review of known plants in synoptical form. In his Institutiones Rei Herbarie
(published 1700) 10,146 species of plants are distinguished and arranged in 698
genera, which again are assembled under 22 classes. Classes 1-15 include herbs
and under-shrubs, 16 and 17 flowerless plants (Cryptogams), and 18-22 shrubs
and trees. The herbs, shrubs, and trees are distinguished by the form of their
flowers, especial importance being attached to the presence of calyx and corolla,
to the regularity or irregularity of the flower, and to the petals—whether they
are free or united with one another. Not long afterwards Linneeus produced
a classification of plants based on the distribution of the sexes, and especially upon
the number of the stamens in the flowers. The terms species and variety, genus
and class, were more clearly and intelligibly defined than heretofore, and his 1050
genera were included under the 24 classes already enumerated (p. 288). The
Linnean classification, known as the Sexual System, enjoyed an unprecedented
recognition. It constituted a well-arranged summary of a great mass of scattered
observations, and made it possible for species to be identified by means of concise
descriptions. It was not the fault of this accomplished and renowned naturalist
if a greater importance were attached to his system than he himself ever intended.
Linneus never regarded these 24 classes as real and natural branches of the
vegetable kingdom, and expressly says so; it was constructed for convenience of
reference and identification of species. A real natural system, founded on the
true affinities of plants as indicated by their structural characters, he regarded

602 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

as the highest aim of botanical endeavour. He never completed a natural system,
leaving only a fragment (published 1738).

The credit of actually founding a natural system of plants is usually attributed
to Bernard de Jussieu (1699-1777) and his nephew Antoine Laurent de Jussieu
(1748-1836). For many years this system only found expression in the laying
out of the beds in the Botanic Garden of Trianon (at Versailles); it first became
generally known some thirty years after its inception, when the younger de
Jussieu published his Genera Plantarwm (1789). A hundred families of plants
are distinguished and grouped under fifteen classes, which, in their turn, fall
under three main co-ordinated divisions (Acotyledones, Monocotyledones, Dicoty-
ledones). The three main divisions! are founded upon the structure of the
embryo at germination. In the Acotyledones the embryo consists of but a
single cell and is destitute of cotyledons, in the Monocotyledones it is multicellular .
and provided with one cotyledon, whilst in Dicotyledones there are two cotyledons.
The Acotyledones are equivalent to the Cryptogamia of Linnzus (his 24th class,
cf. p. 290) and constitute the Ist class of the new system. The Monocotyledones
fall into three classes according to the relative position of the stamens to the
ovary (Monohypogyne, Monoperigyne, Monoepigyne). The Dicotyledones are
first subdivided into three groups according to the structure of the perianth,
viz., into those destitute of petals (Apetale); those with distinct calyx and corolla,
the petals being united (Monopetalz); and those also having calyx and corolla,
with all the petals free from one another (Polypetalz). Each of these groups is
subdivided into three classes, based on the relative position of stamens to ovary
(in the case of the Monopetale of corolla to ovary). Since in the Dicotyledones
with unisexual flowers it was impossible to indicate the relative position of
stamens and ovaries, a special class (Diclines irregulares) was set aside for them.
The institution of this last class does not mark an advance towards a natural
system; whilst the limitations of the other classes in respect of the relative positions
of stamens to ovary is cumbrous and unnatural, still they are less artificial than
those of the Linnean Sexual System. The distinctive features of the system of
de Jussieu are the broad characters upon which the families are based—the whole
structure of the plant being taken into consideration—and especially the recogni-
tion of Monocotyledons and Dicotyledons as equivalent groups of Flowering

1A. L. DE JUSSIEU’S SYSTEM OF 1789.

Acobyledomes 2.4 scx cansnyael sissies cdageuasen sgevany Serie sick 4. yee chp hoeaa shiaisvau bebe icevse aden eiwuuoraey oT
Stamina hypogyna....
Monocotyledones ..............ccccceeseceseeee perigyna, .... TH
epigyna .... :
Stamina epigyna............eeceeee Vv
Apotale we. MPOVIS YA se Sins inuandutseen neragaaiascacaneacndesind we [.
hypogyna ‘
Corolla hypogyna ............ . VIII
: M Pata cas. perigyna....... X.
Dicotyledones onopevale apievna ae connatis A
Le. pisy distinctis. .. XL
AMMA CPIQYNA..........ccceeecccecesceeeeeeeeenescecurseeceusceuns
Polypetalee.............. HY POD YMA a cearscomsn de ates aintaeeipurertiahnd “accumkacseece ait

erigyna.. 4
Diclines irregulares si Nich eaeimes ee NN cee cess gees aoe

OLDER SYSTEMS OF CLASSIFICATION, 603

Plants. A. P. De Candolle! (1778-1841) in his Théorie Elémentaire de la Botanique,
ou Exposition des Principes de la Classification naturelle (published 1813), dis-
tinguished between cellular and vascular plants (Cellulares and Vasculares). The
former are constructed of cells alone, whilst in the latter vessels also are
met with. The cellular plants were divided into those without leaves (Cellu-
lares aphylle) and those provided with leaves (Cellulares foliacesw). The
vascular plants were divided according to anatomical views current at the
time into those in which the vascular bundles were scattered through the stem
and were supposed to originate from within (Endogens), and into those in which
the vascular bundles were arranged in a ring and were added to from without
(Exogene). The group Endogene included the Vascular Cryptogams (Endogene
cryptogame), forms destitute of flowers, and the Monocotyledons of de Jussieu
(Endogene phanerogame). The Exogene, the equivalent of de Jussieu’s Dicoty-
ledones, were divided into those with a simple perianth (Monochlamydez), and
those with a distinct calyx and corolla (Diplochlamydez). The latter are further
subdivided into three groups: the Corolliflore, in which the petals are united
into a continuous corolla; the Calyciflore, in which the petals are inserted upon
the calyx; and the Thalamiflore, in which the petals are free and inserted upon
the floral receptacle. Although De Candolle based his system upon characters
essentially different from those used by de Jussieu, and although in both systems
there are many deviations in the limitations of the classes and families, there is
on the whole an agreement in many essential particulars. Especially may we
note the recognition of Monocotyledons and Dicotyledons (though under different
names) as the two contrasting main divisions of Flowering Plants. And further,
that the Cellular and Vascular Cryptogams are sharply distinguished from
one another. The main groups, the Cellular and Vascular Cryptogams, the Mono-
cotyledons and Dicotyledons, are met with (under various names) from this time
onwards in all later schemes of classification; and, so far as we can tell, appear
to constitute so many natural groups—groups, that is, of which the members
are all more nearly allied by descent to one another than to the members of the
other groups.

Following De Candolle many Botanists elaborated schemes of classification
during the first half of the nineteenth century; these included Reichenbach, Oken,
Agardh, Martius, Brongniart, Bartling, Endlicher, Lindley, and many others. To
the non-botanist, recognizing the fact that there can be but one real natural system

14, P, DE CANDOLLE’S SYSTEM.

I. VASCULAR OR COTYLEDONOUS PLANTS. VASCULAR OR COTYLEDONOUS PLANTS
1. Exocena or DIcoTyLEDONs. (continued).
a. Perianth double (calyx and corolla). 2, EnDocuNa OR MONOCOTYLEDONS.

Thalamiflore (petals distinct, inserted on A, Phanerogams (=true Monocotyledons).
the receptacle). B. Cryptogams (=Vascular Cryptogams and

Calycifloree (petals free and inserted on Naiadacez).
the calyx). II. CELLULAR OR ACOTYLEDONOUS PLANTS.
Corolliflorse (petals united together). A. Foliacese (leafy=Mosses and Liverworts).

B. Monochlamydee (perianth simple). B. Aphylle (not having leaves=Thallophytes.)

604 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

of plants, this great variety of specialist opinion is somewhat surprising, and tends
to shake his confidence in all botanical systems. But it must be remembered that
in the development of a natural system the imagination plays a much more im-
portant part than in the elaboration of an artificial one, nor can prevailing currents
of thought, or the particular habit of mind of the observer, be without their in-
fluence. Very prominently does this appear in the case of the Botanists who came
under the influence of what has been termed nature-philosophy during the early
portion of this century. Thus Reichenbach and Oken proposed systems which can
only appear to us absurd; but it would be wearisome and useless to follow their
absurdities in detail.

The system of classification proposed by Endlicher? (1805-1849), and published
in his Genera Plantarum secundum ordines Naturales disposita (published 1836-
1840) is based on the systems of de Jussieu and De Candolle. In it 6838 genera,
arranged in 277 families or orders, are included. Here for the first time are the
Coniferz and Gnetaces distinguished as a special group, and designated as Gymno-
sperms. Here also is that group of cellular plants known as the Thallophyta care-
fully distinguished into three series, the Algw, Lichens, and Fungi. But we still
find these groups treated as equivalent to the Horse-tails, Ferns, Lycopods, &.; so
also with the Gymnosperms, they are not treated as a distinct subdivision, but only
as a class of Dicotyledons (Acramphibrya), the other classes of which are the
Apetala, Gamopetala (= Monopetale), and Dialypetala (= Polypetale).

In fairly recent times Bentham and Hooker, in their well-known Genera Plant-
arum (published 1862-1883), follow essentially the systems of De Candolle and
Endlicher. They assemble all flowering plants (100,220 species) into 8417 genera,
and these under 210 families or orders. Of these orders 3 belong to the Gymno-
sperms, 35 to the Monocotyledons, 36 to the Monochlamydez, 46 to the Gamopetale,
and 90 to the Polypetale.

1 ENDLICHER’S SYSTEM.

I. THALLOPHYTA (no opposition of stem and root). Il, CORMOPHYTa—Continued.
PRoroPpHyYta. AMPHIBRYA (stem growing at the circum-
Alge. ference).
Lichenes. Includes Monocotyledons,
HYsSTEROPHYTA,
Fungi. ee rene acts aes at both point
a and circumference).
II. CORMOPHYTA (opposition of stem and root). Gymnosperma (ovules naked, fertilized
ACROBRYA (stem growing at the point only), directly from the micropyle).
Anophyta (Liverworts and Mosses), Apetala (Perianth 0, rudim. or simple).
Protophyta (Vascular Cryptogams and Gamopetala (Perianth double, petals
Cycads). ; united),
Hysterophyta (certain parasites, Bala- Dialypetala (Perianth double, petals
nophorez, Rafflesiaceze, &c.), free).

*THE MAIN DIVISIONS OF BENTHAM AND HOOKER’S SYSTEM
(For FLOWERING PLants ONLY).

DIcoryLEeDongs, DicoryLeponrs— Continued,
Polypetale, Monochlamydez,
Gamopetale, Gymnosperme,

MonocotyLepoyes,

CLASSIFICATION OF THALLOPHYTES. 605

Though the grouping of Dicotyledons (according to the characters of the
perianth) into Monochlamydew (= Apetale), Gamopetalz (= Monopetale), and Poly-
petal (= Dialypetale), is very generally recognized to be an unnatural one, it is
no easy task to replace it by a better one. The families belonging to the great
group Dicotyledons show the most multifarious relations to one another. An
arrangement, based on the assumption that these families have been developed one
from another, is not discoverable; whilst an arrangement in linear series is as
unnatural as one resembling a tree with its branches. Very appropriate was
Linneus’s comparison of the limitations of these families with the dovetailing of
the frontiers of countries on a map. One family stands in touch with two, another
with three, others again with four or more allied families. This contact or rela-
tionship occurs on the most various sides. Some families are extremely large and
comprehensive, others relatively small, and, as it were, jammed in between them;
whilst others resemble scattered islands off the coast of a continent.

Well worthy of consideration is the system of Alexander Braun,! published in
1864 in Ascherson’s Flora der Provinz Brandenburg. Though the division of
Dicotyledons into Apetale, Sympetale, and Eleutheropetale suggests at first sight
the classifications of de Jussieu and Endlicher, there is a difference, and an important
one. A large number of the families included by the older Botanists in the Apetale
are here placed in the Eleutheropetale. With the Eleutheropetale are ranked
those plants “in which calyx and corolla are typically present, the latter consisting
of separate petals”. They are ranged in 24 Alliances or Cohorts—Hydropeltidine,
Polycarpice, Rhceadine, Parietales, Passiflorine, Guttifere, Lamprophylle, Hes-
perides, Franguline, Aisculine, Terebinthine, Gruinales, Columnifere, Urticine,
Iricoce, Caryophylline, Saxifragine, Juliflore, Umbelliflore, Myrtiflore, Thy-
melinz, Santalinz, Rosifloree, Leguminose. In recent times we have the systems
of Kichler and Engler. They follow the lines laid down by Alexander Braun, but,
carrying his method further, the group Apetale (or Monochlamydez) is entirely
abolished, its members being referred in part to the Sympetale, and in part to the
Eleutheropetale (=Archichlamydez of Engler).

During the last fifty years our knowledge of the Cryptogams constituting the
group Thallophyta (founded by Endlicher, ¢f foot-note, p. 604) has increased by
leaps and bounds. Several attempts have been made to bring together the results
of the various researches upon this group, and to utilize them for classificatory

1 ALEXANDER BRAUN’S SYSTEM.

I. BRYOPHYTA. Ill ANTHOPHYTA (Flowering Plants).
1. Thallodea (Algz, Lichens, and Fungi). A. big neecmen sae exposed).
2. Thallophyllodea (Characez, Mosses, and » Mrondeas (Cycais),

2. Acerose (Conifers).

B. ANGIOSPERM4 (seeds in an ovary).
1. Monocotyledones.
2. Dicotyledones.

1. Phyllopterides (Ferns and Equisetums). a. Apetale.

2. Maschalopterides (Lycopods), 6. Sympetale.

8. Hydropterides (Rhizocarps). ¢. Eleutheropetale.

Liverworts).

II, CORMOPHYTA.

606 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

purposes. The old division into Algew, Fungi, and Lichens, based on the presence or
absence of chlorophyll and on the mode of life of the forms in question, has been
by many authors abandoned. Cohn in 1872 divided the Thallophytes, according to
their methods of reproduction, into seven groups: Schizosporex, Zygosporee, Basidio-
spores, Ascospores, Tetrasporex, Zoosporeze, and Oospore. Sachs, in 1874, follow-
ing somewhat similar lines, made four classes: Protophyta, Zygosporee, Oosporee,
and Carposporee, in each of which groups both chlorophyll-containing (Algz) and
colourless forms (Fungi) occur, as may be seen by a perusal of the classification
quoted below.! Gebel (1882) returns in part to the older method and distinguishes
between Alge and Fungi; but with these as groups of equal systematic importance
he ranks the Myxomycetes, Diatomacex, and Schizophyta. The Alge he divides
into Chlorophyces (Green Algz), Pheophycee (Brown Alge), and Rhodophyces
(Red Sea-weeds); and the Fungi into Chytridiacex, Ustilaginee, Phycomycetes,
Ascomycetes, Acidiomycetes, Basidiomycetes. Warming (1884) returns completely
to the older method, dividing the Thallophytes into Algz and Fungi, ranking the
Myxomycetes with the Fungi, and the Diatoms and Schizophycez with the Alga.
The balance of opinion at the present time, largely swayed by the views and
researches of Brefeld upon the Fungi, favours a grouping of the bulk of Thallo-
phytes into Algw and Fungi. Brefeld regards the various families of Fungi as
more intimately related amongst themselves than are these families to corresponding
families of Alge. That Fungi have arisen from Alge at some remote period, and
have then amongst themselves undergone development along various lines, is very
generally held; but the view that the different families of Fungi stand in near
relationship to the several algal groups—as indicated, for instance, in the system of
Sachs, (cf. foot-note below)—is not at present the prevalent one. And amongst the
Algz, also, the attempt to classify the various forms into families according to the
relative simplicity or complexity of their organs of reproduction (as Sachs suggested)
no longer finds general favour. Amongst the Algw we find a number of extensive

1SACHS’S CLASSIFICATION OF THALLOPHYTES.
I. Proropuyta.

Containing Chlorophyll. Not containing Chlorophyll.
Cyanophycez. Schizomycetes.
Palmellaceze (in part). | Saccharomycetes,
II. ZyGosPoREs.
Conjugating Cells Motile.
Pandorinez Myxomycetes.
(Hydrodictyez).

Conjugating Cells Stationary.
Conjugatz, | Zygomycetes.
II. Oosporea,

Sphzroplea.
Vaucheria ... ... (Coeloblastee), es ha a

: Peronosporese.
Volvocines.
Gdogones,
Fucoidez.

IV. CarposPores,

Coleochsetem, Ascomycetes (including Lichens).
Floridez. Aicidiomycetes (Uredinez).
Characeze, Basidiomycetes.

THE EVOLUTION OF PLANTS. 607

groups, within the limits of each of which all stages of complexity in reproduction
occur. The attempt to string together forms agreeing in reproductive methods
makes it necessary to break up groups which on general grounds seem to be natural
families. And as it is a natural system that we are striving after, systems like that
of Sachs (which may be compared to the artificial sexual system of Linnzeus) must
be abandoned. That the publication of the Sachsian system in his widely-read
“Text-book” has done great service to Botany there can be no doubt; it has stimu-
lated thought and observation, and has led more speedily than would otherwise
have been the case to the establishment of broad and probably sound views as to
the relations of the Thallophytes. However, the Myxomycetes, approaching as they
do certain groups of the animal kingdom, are kept apart from the rest of the
Thallophytes in the most recent system.

The classification of plants according to their similarity of structure—species
into genera, genera into families or orders, families into alliances or cohorts, these
into classes, and classes into two chief branches or phyla, the Cryptogams and
Phanerogams—leads to the presumption that these two chief branches have arisen
from a common stock, have diverged from a common stem. A consideration of all
animal and plant forms similarly leads us to the belief that the main stems of
the Animal and Vegetable Kingdoms, respectively, meet at their points of origin.
By studying systems of classification drawn up on paper and restricted to two
dimensions of space, we involuntarily conceive the classes and orders of the vegetable
kingdom, as a tree which continually branches, finally ending in thousands of twigs
which represent the various species. Such is, rightly or wrongly, the conception of
all Botanists who have concerned themselves with the construction of a natural
system. They only differ in so far that some regard the Thallophytes as standing
at the base, and derive from these the Liverworts and Mosses, from these the
Ferns, &c., and so on to the Gymnosperms and Angiosperms; whilst others make a
subdivision of the main trunk at once into Cryptogams and Phanerogams, each of
these continually branching according to the various classes and families. Others
again, whilst conceiving the whole vegetable kingdom as having a common origin,
regard this as the centre of a sphere, and that the several phyla and classes radiate
out from this, producing numerous branches and twigs at the surface of the sphere.
Each of these hypotheses presupposes, in the first instance, the existence (or spon-
taneous generation) of a few Thallophytes of extremely simple structure which have
become differentiated, i.e. given rise to more complex offspring which form the
beginnings of the branches of the tree. To this kind of development of a tree-
structure, the terms Phylogenesis or Phylogeny (from gu, a tribe; and yerdw,
to produce) is given. Obviously, not only the original forms possess the capacity
of differentiating, but their offspring also, and so on through the entire tree. But
views are divided as to whether this continued differentiation follows a predeter-
mined plan, is due to definite inherent forces, or whether it may not be restricted in
this sense and due to other and external causes.

608 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

That a natural system has been evolved along lines resembling the ramifications
of a tree, which commenced with simply organized structures and terminated with
the most complex ones, finds a certain confirmation when the history of develop-
ment of the individual (ontogeny, from a», ros, being; and yerdw, to produce) is
compared with its position upon the phylogenetic tree. As we know, the greatest
of all flowering trees begins its existence as a single protoplasmic mass. This
surrounds itself with a cell-wall and increases in size and complexity at the expense
of nutriment derived from its environment. Gradually cells and tissues arise and
the young organism becomes segmented into an axis and appendages. These, again,
assume the most varied forms corresponding to a subdivision of labour. Ultimately
the uppermost and last-produced members of the plant are transformed into flowers
and fruits. It is thought that, just asa plant is gradually differentiated in this way
so have all plants undergone a similar transformation, step by step. The egg-cell,
the starting-point of the individual, may be compared to a Myxomycete, the cell-
complex which arises from the egg-cell after fertilization to a Thallophyte, the
segmented axis and appendages of the seedling to a Vascular Cryptogam, and the
complete plant-body, finally, to a Flowering Plant.

This comparison, like so many others which captivated the imaginative faculties
in the days of the speculations of nature-philosophy, has found many adherents;
indeed, it has served as dogma and guiding light in many investigations. But it
is difficult to harmonize it with other theories well-proved by experience. The
main burden of this comparison (known as the “ Recapitulation-theory ”) is that
the vegetable kingdom as a whole has undergone a developmental history and
transformation resembling that of a single member of the group of Flowering
Plants. But first it must be asked, what is the meaning of metamorphosis in the
individual, and what object has been attained by it? Though the actual processes
taking place in the living protoplasm in metamorphosis are unknown, this much
seems certain: That these changes occur along lines sufficiently well indicated;
that the fashioning of the successive stages of any given species is accomplished
according to a definite plan; that external influences, such as soil and climate, do
not permanently affect this plan; and that consequently the plan of construction
of these successively appearing stages is laid down in the protoplasm itself. The
ultimate object of metamorphosis in plants is the production of fruit; and with
the formation of an ovary the metamorphosis ends, the fertilized egg-cell beginning
the metamorphosis all over again, 7.e. it is the starting-point of a series of trans-
formations along identical lines. And this applies equally to the Apple-tree and
to the Palm, to the Pine, the Horse-tail, the Moss, the Bladder-wrack, Stonewort, to
the Mould, and to the simplest of green Algew. Only in the last-named forms are
the intermediate stages fewer than in the first-named. But it will hardly be sug-
gested that the latter have not on this account attained the end in view. Simple
plants whose fertilization and fruit-formation is accomplished under water, whether
it be on inundated land, in the mud of a river, or at the bottom of a lake, attain
this end without a complex metamorphosis of petals and stamens; whilst many

THE EVOLUTION OF PLANTS. 609

of the denizens of the ocean have no need of segmentation into stem and leaf.
Indeed, such a metamorphosis for this purpose would be a disadvantage, anything
but a progressive development. Similarly is it inconceivable, from all we know
of the relations between external conditions and the form of an organism, that
a Fern (for instance), unable to accomplish its fertilization in dew or rain-water,
should in consequence depart from its usual habit and strike out a new line of
metamorphosis. Thus we may conclude! that the development of the individual
(Ontogeny) cannot be regarded as an epitome of the ancestral history or line of
descent of that individual, and, further, that ontogeny gives no support to the
assumption of a ramifying phylogenetic tree starting with simple forms and ending
with complex much-differentiated ones.

The results of developmental investigations showing a marked similarity in the
form of organs serving similar purposes in the most different groups of plants have
been brought forward in support of the assumption that Flowering Plants have
arisen from simple Cellular Plants by a series of progressive transformations.
Though these organs are in some groups of more simple, in others of more complex
structure, their similarity is unmistakable; it is upon this that the view is widely
based that organisms exhibiting similar organs have been derived from one another.
But this inference is inadmissible. The similarity in question finds a simpler ex-
planation as the expression of the attainment of a common object. Thus fertiliza-
tion consists in the coming together and uniting of two portions of protoplasm
which have originated at a distance from one another; the similarity of ways and
means in attaining this object are obvious. In one case water is employed as a
means, in another the air. There is, truly, a difference in detail, but the general
similarity remains. From this general similarity all we are justified in inferring is.
that the organisms in question all reproduce themselves by fertilization, not that
they have a common origin.

This conclusion leads to the question whether, in view of the diversity of the
organs of fertilization, several distinct stems of plants may not have co-existed
all along. We know from observation and experiment that new forms do not
as a rule arise from offshoots, but from fruits. New groups of plants might thus
(so it was said) arise from existing ones solely by the sexual method. Complex
Thallophytes might arise from the fruits of simpler ones, Ferns from the fruits
of Mosses, and soon. Assumptions of this kind belong to a period at which the
phenomena of fertilization and fruit-production, especially in the Cellular Plants,
were only very imperfectly understood. No Botanist nowadays would suggest the
possibility of a Spirogyra or a Ulothria, or an Hdogonium, or a Stonewort, arising
from the fruit of a Vaucheria. It might well happen that a new species could
arise by the crossing of two dichogamous species of Vawcheria, but this new form
would be essentially a Vaucheria, and its methods of fertilization would be essen-
tially similar to that of its parent-forms. It is likewise as impossible for the male
protoplasm of a Vawcheria to enter the chamber in which the conjugation of the

1See editorial note prefacing this volume.
Vou. I. 89

610 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

sexual cells of Spirogyra takes place (cf. vol. i. Plate I. fig. 1), or for this spermato-
plasm to fuse with the gametes of Ulothria (cf. p. 49), as for the gametes o
Ulothria to enter and fuse with the egg-cell of a Vaucheria, no new group of
plants could have arisen in this way. We may conclude then that plants belonging
to groups with a marked diversity in their sexual characters have not arisen from
one another, but belong to stems which have co-existed as distinct types from
the first.

Nor must we omit to notice the observations which have been made in regard to
symbiosis and the inter-relations of green and non-green plants. It has already
been pointed out (vol. i. pp. 263, 264) how that the continuation of plant-life, and
indeed all life, is dependent on the activity which saprophytic plants exhibit in the
decomposition of dead organisms. Green plants could not exist independent of
colourless saprophytes, nor these latter without green plants. This must ever have
been the case, and
it must so remain.
We may then draw
another conclusion,
viz. that those colour-
less plants which by
their activity bring
about the decomposi-
tion of green plants

Fig. 365.—Spirophyton from the Upper Devonian. cannot have arisen
from green planis,
but that from the beginning they have belonged to a distinct stem.

It is to Paleontology that we must look for the most trustworthy solution
of the question as to whether numerous plant-stems have existed side by side from
the first, or whether the groups which at present co-exist have in process of time
branched forth from a single stem. Were it a fact that those forms which show
a far-reaching division of labour, and a complex structure of organs, which we term
“higher plants”, have arisen from others of very simple mode of life and possessing
a simple structure and which are known as “lower plants”, then should we expect
the earth to have been covered formerly by lower plants alone. And then, fol-
lowing this epoch, would have come a time when plants would have existed which
might have served as the starting-points of the later-appearing distinct groups. We
should expect to find in those strata of the earth’s crust regarded by geologists
as the oldest of all nothing but the remains of very simple Thallophytes, then,
following these, Wracks, Red Sea-weeds, and Lichens, and after these Stoneworts
(Chara), Mosses, or some other type of plant which, having given rise respectively
to Stoneworts and Mosses, has, after this differentiation, become extinct.

From the graphite, which is looked upon as the oldest trace of vegetable life
on the earth, unfortunately we obtain no conclusive evidence on this matter. From
its presence on slate mountains together with crystalline limestone and pyrites

THE VEGETATION OF FORMER TIMES. 611

we might conclude that it originated from plants adhering to the limestone reefs
formed by animals or from sea-plants which lived on the borders of these limestone
cliffs. Where graphite is found in greatest quantity one is tempted to think it
might have been derived from peat moors. As we have said, all these are merely
suppositions, for since the carbon, lime, and silicates have become crystalline all
the points for the determination of the families to which the graphite-forming
plants belonged are lacking. It might be noted here, by the way, that although
graphite does indeed furnish the oldest traces of plant-life on the earth this does
not prove that the plants which gave rise to it were necessarily the first which

: aie Tie
Fig. 366.—Riella helicophylla growing under water. Enlarged. [ Bibrarc

existed there. It is doubtful whether the rock which is associated with graphite
formed the first hard crust of the earth. Much more probably this rock was com-
posed of other broken rocks just as it has itself been again demolished, furnishing
the material for new strata.

The shapes of vegetable remains from paleozoic formations are fairly easily
recognizable. Those which were formerly regarded as fossil Sea-wracks have
indeed been more recently interpreted as the trails of worms and medusa, but
some of them are without doubt the remains of Sea-wracks. The only other
known lowly plant which at that time had an aquatic habit is the curious
Spirophyton, the so-called Cock’s-tail Alga (see accompanying fig. 365). This,
though some regard it as of purely inorganic origin, may perhaps be regarded
as a submerged Liverwort; at any rate it is not without resemblance to Riella
Reuter, which at the present time lives in the Lake of Geneva, and to the
Algerian Riella helicophylla (see fig. 366). No trace is to be found of Thallo-

612 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

phytes which may have existed on land, but we have huge tree-like Vascular
Cryptogams with trunks, fronds, and leaves which are to be placed side by side
with our present-day Equisetums, Ferns, and Lycopods. Cycads and Conifers
also are not absent from the Coal Measures. No Angiospermous flowering plants
have hitherto been demonstrated in these strata, but it would be foolish to
regard this fact as a proof that neither Thallophytes nor Angiosperms flourished
at this period. That which has been preserved to us from this time certainly
forms but a small fraction of the old vegetation, and is restricted apparently to
the flora of peat-moors which were just as poor in species and just as monotonous
as they are to-day. The plants which at the presené time predominate on the
moors are still the Equisetums, Ferns, Lycopods, and Conifers, and, in tropical
regions, the Cycads; only a few species from each group, but standing in thousands
side by side and aggregated into dense communities. Anyone who has worked
out the history of these moors knows that the soil must have been prepared
for these plants by other growths. Hquisetwm limosum, Aspidium Thelypteris,
Lycopodium imundatum, &., do not flourish in soil poor in humus; in order
to obtain their requisite food and to develop they require soil which is saturated.
with the dead remains of earlier settlers. Experience tells us that the plants
which appear as the first inhabitants belong to widely different groups (see vol. i.
p. 268). Now if we hold to the view that the formation of peat-moors in long-
past ages occurred just as in the present day, we must assume that the colonies
of Equisetums, Ferns, Lycopods, and Cycads were preceded by other plants which,
as the first settlers, prepared the soil. We cannot indeed determine from the
surviving remains to which groups these first settlers belonged; but, looking back
on the history of our present peat-moors, it seems not improbable that among
them were both Thallophytes and Angiospermous flowering plants.

The fact that the fossil remains of Equisetums, Lycopods, and Cycads, which
spread so widely over the peat-moors of paleeozoic times, have reached us in such
good condition is explained by the presence of humus-acids, which are formed
universally in the peat (see vol. i. p. 263). There are four conditions which render
it possible for a plant to be preserved as a fossil: humus-acids form the first; the
second is the resin which exudes from the pine-wood and forms amber; the third is
mud and sand brought by floods; and the fourth the silicification and calcination of
the cell-wall or the formation of a lime incrustation which is precipitated from
calcareous water on to the various parts of the plant. It is certain that these four
conditions have always been effective, but it is doubtful whether all the fossils
formed in the fourth manner at all periods have remained. For many older strata
have long been destroyed and used in the building up of younger layers, and many
risings and sinkings of these strata have taken place. It would indeed be difficult
to find a single place on the earth’s surface which has not been repeatedly above
and under the sea. Much that might lead us to definite conclusions at present lies
inaccessible to us, covered with immense masses of water at the bottom of the sea,
and the view has actually been suggested from studies made on the few accessible

THE VEGETATION OF FORMER TIMES. 613

and closely investigated spots on the earth’s surface that the fossil remains found
there are not more than a minute fragment of the vegetation of periods long
elapsed.

With these remarks we might mention that it is not beyond the range of possi-
bility that, in addition to the Vascular Cryptogams, Cycads, and Conifers growing on
peat-moors, plants of other habitats, especially those of fresh and salt water, or
perhaps of sand-dunes and river-banks, might be found in the strata of paleozoic
times. But no one would doubt that among these would be Angiospermous Phane-
rogams, and this throws some light on plant remains which have come to us from
the mesozoic period. For example, in the upper layers of the chalk we find, in
addition to the plants of peat-moors, the inhabitants of a luxuriant forest-flora of
Angiospermous flowering plants. There are Planes, Birches, Beeches, Oaks, Poplars,
Willows, Fig and Laurel trees, Maples, Ivy and other Araliacesw, Bread-fruit trees,
Tulip-trees and Magnolias, Cherry-trees, and Leguminose of the division Czsal-
pines, Palms, Rushes, and Grasses. If we do not believe in the theory that these
Angiosperms were first created in the mesozoic period, and still less in the greater
marvel that they have sprung from the Vascular Cryptogams, Cycads, and Conifers,
we are forced to the conclusion that they too must have existed as far back as the
paleozoic time. It is to be specially noted that not the slightest trace of inter-
mediate or transitional forms which might connect the aforesaid Angiospermic
Phanerogams with the Gymnosperms or with the Vascular Cryptogams has been
found. One leaf is immediately recognized as belonging to a Tulip-tree, a second to
Maple, a third to a Fig-tree, a fourth toa Palm, &., but no plant has been discovered
anywhere which would perhaps form a connecting link between the Palms or Figs
and the Conifers or Vascular Cryptogams.

Even a cursory glance at the plant-forms named shows that they were members
of mixed forests. It may be assumed, however, that other plant communities peopled
the earth at the same time as these forests. The rocky terraces and boulders, as
well as the flat dry land, were certainly not destitute of vegetation. Nor is it
surprising that no fossil remains of the inhabitants of these places have remained.
The under-shrubs and herbs of a dry soil decompose immediately after their death,
and leave behind only formless humus, which mixes with the soil. Just as little
fossil remains will reach posterity of the Lichens and Mosses, Pinks and Composites,
Saxifrages and succulent plants which inhabit the rocks on the dry mountain-
slopes at the present day, as of the Tulips and Irises, Umbelliferze and Saltworts of
the steppe-flora; and a great mistake would be made if, millions of years afterwards,
it were reasoned from the lack of fossil remains of these. plants that they could not
have existed in our time. It would be just as wrong for us to argue from the
absence of such plants in the strata of earlier periods that they had never existed
in those times. The same thing applies to most fresh-water and marine Alge, and
to the numberless saprophytes which effect the destruction of dead animal and
vegetable: bodies above and under water, and thus maintain the eternal cycle of life
as a whole. Of the first-mentioned the only fossil remains which can be recognized

614 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

are those of Diatoms, whose cell-wall is transformed into an imperishable siliceous
frustule, together with those Floridese which provide themselves like corals with a
calcareous skeleton, and some tough Sea-wracks. It is, however, a very significant
fact that the innumerable fossil Diatoms which come to us in so-called tripoli-powder
and Diatom-earth, and the many calcareous Floridez which come down to us as
Nullipore banks are deceptively like those living at the present day, that these
groups have remained unaltered for eons, and that no form has been discovered in
any of the older strata which could be regarded as a link with another group. No
fossil remains are known beyond doubt to exist of the numerous aquatic plants
with delicate cell-walls which perish as rapidly as they develop, of the Spherella
species which give a red colour to rain-water and to the snow-field, of the micro-
scopic Desmids, of the green filaments of Spirogyra, of the remarkable green tubes
of Vaucheria pictured in plate I, &c. Some woody Polyporus species of Fungi have
reached us, but in forms which look very like those at present growing on old
tree-trunks. Some species of Moulds have been preserved in amber. I have before
me a piece of amber in which insects are imbedded; from one of them spreads a
web of mycelial threads which doubtless belonged to some mould-like Fungus such
as to-day attacks various insects. The myceliums of various Fungi, also, are found
penetrating the tissues of many of the fossil cryptogamic stems of the Coal Measures.
This fact is very instructive, since it shows that in the tertiary period, and in much
earlier periods also, the relation of saprophytic plants to the dead bodies of
animals and plants were the same as they are to-day. All these results taken
together prove that delicate Thallophytes whose cells do not become siliceous or cal-
careous, or which are not inclosed in resin, cannot be preserved in a fossil condition.
But no one would conclude from this that the groups to which such delicate
growths belong were not represented in earlier periods.

On comparing the past and present of the Vegetable Kingdom from these points
of view, more especially with regard to the question whether existing groups
stood side by side in earlier periods also, or whether, in the course of time, they
have sprung from a single individual or from a few spontaneously-generated indi-
viduals, we are obliged to decide in favour of the former. The so-called “ higher”
plants are not derived from the so-called “lower”; the groups of higher and lower
plants co-existed from the beginning side by side. But variations within the limits
of each group have always taken place. New species, i.e. new groups of species,
arose in consequence of the crossing of the species already in existence. Of these
the species which were best suited to the climatic conditions of the time being
survived. But the variation in the formation of new species never went so far as
to do away with the characteristics of the group. We immediately recognize in
the fossil Laurel-trees, Magnolias, Oaks, Palms, Grasses, Pines, Equisetums, Ferns,
Lycopods, Floridex, Diatoms, and Moulds the ancestors of the now existing species.
This would be impossible if the group-characteristics had disappeared in the modifi-
cations which the species have undergone.

When I now attempt the task of stating in detail what has been furnished by

THE SUBDIVISIONS OF THE VEGETABLE KINGDOM. 615

theoretical considerations, and of bringing forward the various groups which have
from the beginning existed side by side, distinguishing them by the enumeration
of their peculiar characteristics, I am not blind to the enormous difficulties of the
undertaking. Although Paleontology, Morphology, and Physiology afford valuable
results, they are not enough, and neither of the three sciences gives sufficient data
for the complete solution of the problem. One of the greatest obstacles is the afore-
said incompleteness of the geological record. From the existing remains we may
indeed conclude on the whole that numerous groups stood side by side in the
mesozoic and palsozoic periods, but the evidence of many groups which exist at
the present day without transitional forms is wanting, and when we assume their
existence we make use indeed of a justifiable hypothesis, but have no proof what-
ever. The danger, on the other hand, of establishing homologies from the similarity
of an organ which is observed in groups of species now living has already been
mentioned (see p. 609). Up to a certain point all organs which have similar work
to perform agree with one another. This agreement is the more pronounced the
greater the similarity of the conditions under which the organs have to do the
work. Species of very different groups which live under water exhibit many
characteristics in common; plants whose pollen-grains are transported by the wind
show a great agreement in the structure and position of the parts of the flower.
In the same way the form of flower-visiting insects necessitates a number of similar
characteristics in the flowers visited. For example, we might instance the sweep-
ing hairs on the style of the Proteaces and of the Composites, as well as certain
developments which are met with in the flowers of Aroids, which are visited by
small flies, and also in the Aristolochiacez. In spite of this consideration, however,
the similarity in the structure and form of organs, both of those serving for pro-
pagation and for nourishment and growth, must obviously be kept to the forefront;
similarity must always be an important factor in the limitation of groups.

As we have in the preceding chapter established the fact that each species is
built up by protoplasm with a specific constitution, the question might be pro-
pounded whether each plant-group has not something in common in this respect.
Many observations argue differently for this view. It has been repeatedly stated
that the Moulds, Oscillatories, Sea-wracks, Stoneworts, &e. give off a scent which,
although it differs according to the species, is yet very similar upon the whole, and
that one is justified in assuming a specific constitution of the protoplasm in each of
these groups on this account. Moreover, the scent which the Mosses exhale is
found in no other group of plants. The same is true of Ferns. The delicate fronds
of the tropical Filmy Ferns exhale the same peculiar scent as the larger Ferns of
our forests. The Conifers, Umbelliferee, Labiatese, Leguminose, and Cruciferse
exhibit similar conditions. Is it not also a striking phenomenon that the parasitic
Fungus Cronartiwm asclepiadewm should settle on Cynanchum Vincetoxicum, as
well as on Gentiana asclepiadea, t.e. upon two plants which the Botanist certainly
places in different families, but which he regards as belonging to the same alliance?
To these facts many others might be added, especially with regard to the choice of

616 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

vegetable food by animals. But our knowledge in this respect is so fragmentary
and uncertain that for the present we cannot make use of these conditions in the
limitations of the groups.

The capacity for sexual union is of the utmost importance in defining plant
groups. Species which can unite sexually belong undoubtedly to the same group.
Nothing can be urged against this principle, and if it could be universally applied,
the division of the groups would be settled. But in this matter there are very
many pros and cons. The converse of the proposition requires consideration. It
will not do to say that all plants which cannot unite sexually belong to different
groups. It has been shown that crossings can be successfully effected in Orchids
which all Botanists regard as members of different genera, but, on the other hand,
it is demonstrated that crossings between very similar species of the Umbellifer
family lead to no fruit formation. No one, however, would conclude from this
that these Umbellifers belonged to different groups. On reflecting in what a small
number of flowering plants the fertilizing process has hitherto been observed, and
remembering that the fertilization of many Thallophytes is still totally unknown,

_the hope of being able to utilize these conditions in limiting the groups becomes
very much lessened.

In the review of the various groups of the vegetable kingdom which follows?
no attempt is made to present the groups in the form of an ideal natural system.
So far as the Thallophytes, Bryophytes, Pteridophytes, and Gymnosperms are con-
cerned, there is a very general consensus of opinion amongst Botanists, and the
serial arrangement here followed is in harmony with it. But as regards the Angio-
spermous flowering plants, and in particular the Dicotyledons, it is as yet too early
in a book of this nature to embody all the most recent suggestions as to the affinities
of the various families. Attention was drawn on p. 605 to the system of Alexander
Braun, and it was pointed out that he was the first to try and break up the large
and unsatisfactory class Monochlamydee or Apetale, and to relegate its families in
part to their true position. This attempt has been very fully carried out by Kichler
(1883), and by Engler (1892); these two Botanists admitting only two classes of
Dicotyledons (Choripetalz or Archichlamydez and Sympetale). But as yet many of
their placings of individual families are but tentative, and we may well wait a few
years for a system on these lines to settle down into more or less permanent form. An
instance of too hasty rearrangement of a natural system to meet recently discovered
facts may be quoted here. In 1891 Treub discovered that Casuarina possessed chala-
zogamic fertilization, and in 1892 Engler (following Treub) separated Casuarina from
all other Angiosperms as the sole genus in a new class Chalazogamex. Since then
it has been found (see p. 413) that chalazogamic fertilization is much more general
than was at first supposed, and that in the group Amentaces it is widely spread,
though by no means of universal occurrence. To break up the Amentacesw in the
drastic manner involved, if the class Chalazogame be maintained, seems a most

1Cf. editorial note at commencement of this volume.

THE SUBDIVISIONS OF THE VEGETABLE KINGDOM. 617

undesirable and unnatural thing to do; it will on the whole be best to abolish a
special class of Chalazogams, and, if thought necessary, to rearrange the families
which constitute the Amentace, but not to sever them from one another. For the
Angiosperms we shall in the main follow the arrangement of the well-known
Genera Plantarum of Bentham and Hooker, though we reserve our freedom to
deal with certain families as seems well to us.

The vegetable kingdom we divide first into four main divisions or phyla: (1) The
Myxothallophyta, including the Myxomycetes only, a group standing apart from
(2) the Thallophyta, which include the various classes of Algee and Fungi. Then
follows (8) the Archegoniatz, forms possessing archegonia and fertilized by motile
spermatozoids, and including the Liverworts and Mosses, and the series of the Ferns
(Phyla (1) (2) and (8) constitute what are usually referred to as “Cryptogains”), and
(4) the Phanerogamia or flowering plants, fertilized by means of pollen-tubes. They
fall into two sub-phyla, Gymnosperms and Angiosperms, and the latter mto two
classes, Monocotyledons and Dicotyledons. Finally we have the 3 sub-classes of
Dicotyledons—Monochlamydex, Monopetale, and Polypetale. Here, in outline, is
the system :—

(1) MYXOTHALLOPHYTA, containing 1 class only.

(2) THALLOPHYTA, containing 5 classes.
I. Schizophyta.
II. Dinofagellata.
Ifl. Bacillariales,
IV. Gamophycec.
V. Fungt.

(3) ARCHIGONIATA, containing 2 classes.
I. Bryophyta.
II. Pteridophyta.

(4) PHANEROGAM, containing 2 sub-phyla,
A. GYMNOSPERMZ.
B. ANGIosPERM#, containing 2 classes.

I. Monocotyledones.

II. Dicotyledones, containing 3 sub-classes.
a. Monochlamydee.
b. Monopetale.
ce. Polypetale.

Each class (or sub-class) is further divided into a number of cohorts or alliances,
and each of these alliances into orders or families. The alliances will be taken one
by one in the following pages, their main characters generally indicated, and the
families which they comprise enumerated. It will not be possible within the limits
of this book to deal with the several families in at all a comprehensive manner,
though the endeavour will be made to point out structural and other characters of
interest, and where certain genera or groups of genera have a special interest these
will be alluded to. No attempt is made to observe any due sense of proportion in
treating of the different alliances. Thus a small alliance containing but few mem-
bers of especial interest will receive more detailed consideration than one vastly

618 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

larger, the numerous representatives of which are unrelieved in their monotony.
This method, truly, is an unconventional one, but in view of the restrictions of
space, perhaps better suited to our purpose than any other.

PHYLUM 1.—MYXOTHALLOPHYTA.

Organisms destitute of chlorophyll, whose vegetative state consists of a mass of naked proto-
plasm*(plasmodium). Reproduction by spores, from which arise swarm-spores or myx-
amcebee, which unite again into plasmodia.

Alliance I—Myxomycetes, Slime-Fungi.

For the most part saprophytic upon dead organic and especially vegetable sub-
stances; they occur chiefly on accumulations of the dead parts of plants—leaves,

Fig. 367.—Myxomycetes.

1 A group of sporangia of Stemonitis fusca. 2A single sporangium; iti i
a Ca, gium;, x 6. 8 Dendritic mass of sporangia of Spumaria alba on
- Grass leaf. ; 4 Sporangium of Dictydium cernuum; xX 25. 5 A group of sporangia of the sane, 6 ae 7 Sporangia of
eld minutum, ® x 25, 8 Sporangia of Arcyria punicea. 9% Asingle sporangium; x10. 10 Part of the net-like
capillitium of the same; x160. 11 Fructification of Lycogala epidendrum on a piece of wood. 1 Leocarpus fragilis; a
plasmodium on the right; several sporangia on the left. ane

tan, rotting wood, and the like; they are rarely parasitic. Their life-history is as
follows:—On the germination of the spores the membrane bursts, and a slimy,
nucleated mass of protoplasm escapes, which either swims in water by means of a

THALLOPHYTA. 619

single flagellum, or creeps about on a damp substratum; these motile bodies are the
mycamebe. These amoebe increase at the expense of absorbed nutriment, and
undergo repeated division. Ultimately they fuse together into masses of naked
protoplasm—the plasmodiwm-stage—which creep about until spore-formation sets
in. The plasmodium is transformed into the reproductive stage, numerous sporangia
arising all over its surface. This stage in different cases shows the most varied
structure, as may be seen by reference to fig. 367. Either the whole plasmodium is
transformed into a single sporangium, as in Lycogala epidendrwm (fig. 367"), or a
number of sporangia arise. A portion of the protoplasm becomes hardened to form
the wall of the sporangium, whilst the contents is resolved into a mass of dust-like
spores. In addition there arises in the majority of forms a sort of internal skeleton,
the capallitvwm, which may consist either of a number of elongated tubes with
characteristic thickenings on their walls, or these tubes may be united together into.
a continuous network (fig. 367’). On the bursting of the sporangium the spores
are scattered and carried away by currents of air. They germinate when they
reach a moist substratum, and the life-cycle is passed through anew. Under un-
favourable conditions a plasmodium may become encysted, forming a transitory
resting-stage. If placed in water, the plasmodium escapes from the cyst, and
continues its life-history even after a lapse of several months. The substance of
the membrane, whether of the sporangial wall, spores, or capillitium, does not seem
to consist of cellulose, but rather of a congealed protoplasm. We see, then, that the
life-history of a Myxomycete is divided into a nutritive stage consisting of naked,
membraneless, protoplasmic masses, and a sporangial, spore-producing stage. In
respect of their nutritive stage the Myxomycetes very nearly resemble certain
groups of the Protozoa, and on the strength of this resemblance they are regarded
by many Botanists and Zoologists as belonging rather to the animal than to the
vegetable kingdom. In their manner of reproduction they certainly show analogies
to many of the Fungi however.

Plasmodiophora Brassice is a parasitic Myxomycete which attacks the roots of
the Cabbage, causing the disease known as “ Fingers and toes” (cf. p. 522).

Fossil Myxomycetes are not known. About 450 species have been distinguished.

PHyLum 2.—THALLOPHYTA.

A large and very heterogeneous collection of plant-forms is included under this
term. The word (Greek gars, and ¢vrév) literally means plants with undifferentiated
shoots, and includes practically all plants standing below the Mosses and Liverworts
in complexity of organization. It is impossible to characterize positively a group,
or rather a collection of groups, which shows so wide a range of organization as we
find among the Thallophytes. They are often characterized negatively as plants
whose bodies show no distinction between axis and appendages (stem and leaves).
To such a plant-body the name thallus is given. But though this definition holds
good for the great majority of the Thallophytes, yet there are forms (e.g. Bryopsis,

620 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

the verticillate Siphones, Draparnaldia, many of the Brown Sea-weeds) which
do show a distinction between axis and appendages, though the distinction is not
usually so marked as that between the stem and leaves of a higher plant. Simi-
larly, though for the most part possessing a relatively low organization, some
Thallophytes (especially the higher Fungi and certain of the Brown Sea-weeds)
show considerable differentiation of structure. The Thallophyta consist of many
divergent and more or less sharply characterized groups. These include the Green
Alge (Chlorophycec, which includes the alliances Protococcoider, Siphonez, Con-
fervoidex, Conjugate, and Charales), the Brown Sea-weeds (Phawophycec), the Red
Sea-weeds (Rhodophycee or Floridew), the Blue-green Alge (Cyanophycee or
Schizophycece), the Bacteria (Schizomycetes, here included with the last-named
group in one class, the Schizophyta), the Diatoms (Bacillariales), and the Fungi.
Some Botanists consider that the Myxomycetes (or Mycetozoa), and the Dino-
flagellata (Peridinew) are also plants. These last groups are almost certainly
branches of the Protozoa; and though possessing certain plant-like characters (as
indicated above), they show no near affinity with other plant groups. Whether
they should be considered as plants or animals must therefore remain a matter of
opinion.

The same may be said of certain other organisms regarded by zoologists as
Flagellate Protozoa, but showing undoubted affinities with the lower forms of
Green Alge. There exists, in fact, an unbroken series of forms, connecting un-
doubted Protozoa, having mouths by which they eat solid food, with undoubted
green plants depending entirely on soluble inorganic food. The dividing line
between animals and plants is here obviously an artificial one, and is naturally
drawn by different authorities at different points in the series.

The name Thallophyta, then, is given to all plant-forms below a certain grade
of organization, and includes many separate and widely divergent lines of descent.
The Thallophytes may be pictured as the shrubby growth around the base of the
phylogenetic tree representing the plant kingdom. The lower part of the main
trunk of the tree, that is to say, the line of descent by which the higher plants
have originated, is probably represented by certain of the Green Alge,

Class I—SCHIZOPHYTA.

For the most part exceedingly small organisms, which propagate entirely by
asexual methods. They consist of isolated cells, cell-filaments, surfaces, or masses.
Though till recently regarded as without nuclei, these bodies have been found ina
number of forms, and this view is being abandoned. They include both coloured
and colourless forms; but the coloured forms never exhibit pure chlorophyll.

THALLOPHYTA, 621

Alliance Il.—Cyanophycew, the Blue-green Algw.
Families: Chroococcacee, Nostocacec.

Includes pigmented forms in which in addition to chlorophyll phycocyanin is.
present, giving the cells a bluish, violet, or reddish tint. They occur in water or
in moist places, and their cells may be united together into aggregates of various
kinds. The cell-walls are usually mucilaginous, so that the cells or filaments cling
together in colonies, or they are inclosed in special sheaths. The simpler forms.
included under the Chroococcacee are unicellular; the products of their division
may either remain united into colonies or become quite free from one another.
The rest are filamentous, and are included under the Nostocacer, whose filaments.
can become segmented into small portions which move away by a peculiar motion
not yet fully understood (cf. vol. i. p. 40). At times also certain cells become
resting-spores and can endure climatic vicissitudes. They are widely dispersed
over the globe, and are met with in cold glacier-streams and have been found
living in hot springs at a temperature of even 85° C. Some 800 living species are:
distinguished.

Chroococcacec.—Includes the unicellular forms. Gleocapsa (vol.i., Plate I. n, 0)
forms little mucilaginous colonies, often found on the moist window-panes of hot-
houses. Merismopedia forms films on stagnant water, and Clathrocystis like
certain of the Nostocaceew (alluded to below) arises in quantity in water. A
form probably referable to this group (Dermoglea Limi) developed in 1874 in
such quantities: off the Adriatic coasts as to seriously interfere with the fishing
industry. A commission was appointed to investigate the matter, but in six weeks.
the Dermoglea vanished as suddenly as it had appeared.

Nostocacew are, for the most part, filamentous, though in some forms the cells.
may become isolated. Nostoc itself is common, and takes the form of irregular
gelatinous colonies, which contain numerous interwoven necklace-like filaments.
In some districts, owing to its sudden appearance after rain, it has received the
name of “Falling Stars”. This explains the allusion in the following lines from

Dryden’s Edipus:—
“The tapers of the gods,
The sun and moon, run down like waxen globes;
The shooting stars end all in purple jellies,
And chaos is at hand ”.

A species common in China, NV. edule, is used as a thickening for soup, and an
allied form, Hormosiphon areticus, abounds in the Arctic regions upon floating ice.
Anabena Flos-aque, Aphanizomenon Flos-aquee, &¢., appear in fresh and brackish
water—sometimes in enormous quantities, and to considerable depths. The Tricho-
desmium Erythrewm—another of these “flowers of the sea”—referred to at vol. i.
p. 389, belongs also to this group. Very little is really known about the life-
histories of these interesting plants, which so frequently appear in great quantities
at or near the surface of the water and then as mysteriously disappear. But now

622 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

that systematic observations are being made of the organisms which occur at the
surface (eg. at the Biological station on the Pléner See, Schleswig-Holstein) we may
hope that these lacune in our knowledge may be filled up. Recent investigations
(by Klebahn) upon several of these “flowers of the sea” (Glototrichia echinulata,
Anabena Flos-aque, Aphanizomenon Flos-aque, Trichodesmiwm, &c.) seem to
indicate that they possess special organs of flotation designated “ gas-vacuoles”.
It would appear that these natant forms have in consequence a smaller specific
gravity than the surrounding water, and if the surface be quite unruffled tend
to float, whilst any disturbance, such as waves, &., is sufficient to cause their
distribution through the upper layers of the water. Whether these “flowers” pass
another stage deep down in the water is not fully ascertained. Their spores, so
far as they have been observed, do not seem to possess “ gas-vacuoles”, and sink to
the bottom. The phenomenon here indicated is not unlike that occurring in the
Protozoon Areella, the protoplasm of which is able by secreting a bubble of gas to
rise to the surface, and, by absorbing .it, to cause the organism to sink. The
Oscillarias consist of filaments of disc-like cells; they exhibit curious gliding
movements, which have been already alluded to (cf. vol. i. p. 40). Rivularia is
distinguished by the fact that its filaments are whip-like, ending in a fine point,
whilst in Scytonema this distinction of base and apex is not found. They generally
-occur in more or less mucilaginous masses.

A number of the Schizophycez are associated with certain Fungi to form
Lichens (¢f. later, and vol. i. p. 244); and certain of them occur embedded in the
tissues of other plants. Thus species of Vostoc are met with in certain Liverworts
(Anthoceros) and in the roots of Cycas; and Anabena in special cavities in the
leaves of the Rhizocarp Azolla, It is not known what may be the exact physio-
logical relations between these Blue-green Alge and the plants they inhabit—
whether they are parasitic or symbiotic.

Alliance ITI —Schizomycetes, the Bacteria.

On the whole, in the matter of their structure and aggregation, present many
characters in common with the Blue-green Alge. They are, however, destitute of
the characteristic pigment of that group, and pass their lives as parasites and
saprophytes, obtaining their food from ready-formed organic matter. Nuclei have
been distinguished in some few forms, and the cells are inclosed in a membrane
which, though often mucilaginous, does not consist of cellulose. In size the cells
reach very small dimensions, and may be regarded as the smallest of all plant-
forms. A number of different forms are distinguished; the Cocci, consisting of
minute round cells; short rod-like forms, the Bacteria; longer rod-like forms, the
Bacilli; various spiral forms known as Spirillum, Vibrio, and Spirochzte; filamen-
tous forms, Leptothrix and Crenothrix. A very common mode of occurrence of the
various forms is in gelatinous masses, to which the name Zoogloea has been applied
(cf. fig. 368"). Propagation takes place vegetatively by cell-division so long as the

THALLOPHYTA. 623

conditions remain favourable for further growth. When the substratum is
exhausted, &., spores are formed which can remain for long periods—until, indeed,
circumstances are again favourable for renewed development. These spores may
arise either inside the bacterial cells (=endospores), the protoplasm contracting
somewhat and forming a new wall around itself, or the cells may become trans-
formed entirely into spores (=arthospores), the wall becoming specially thickened.
In no case is there any sexual process. Whilst many Bacteria are only known
under certain forms and are regarded as species of the genera Micrococcus, Bac-
terium, Bacillus, Spirilum, &e., others are known which, in the course of their
development, pass through several such forms, and are termed pleomorphic. That
all Bacteria are thus pleomorphic seems improbable, though the discovery that
pleomorphism existed at one time led to the wildest generalizations. Large
numbers of Bacteria display an active movement which, though formerly attri-
buted to various contractions of their bodies, are now known to be due to cilia.
These cilia may be borne in tufts of 5 or 6 at the two ends of the organism, as in
Spirilum Undula, or they may be solitary at one extremity, as in the Cholera
Bacterium (Spirochete cholere: asiatice), or they may be scattered over the surface
of the organism, as in the Hay-bacillus, Bacillus subtilis. It is due to the extreme
fineness of these cilia that they were not recognized long ago.

Though the forms under which Bacteria occur are relatively few, their mode of
life and special activity is exceedingly varied. The interest attaching to Bacteria
rests largely on their effects on the substratum from which they draw their food.
Taking, first, the saprophytes. These split up their substratum into simple sub-
stances. In some cases there is a complete oxidation, with production of carbon
dioxide and water; in others this is only partial, as in some of the cases of
fermentation, e.g. when alcohol is oxidized into acetic acid by the activity of the
vinegar organisms Bacillus and Micrococcus aceti (cf. figs. 368° and 3684). Or
there may be a decomposition unaccompanied by simple oxidation, as in many
cases of fermentation, ¢.g. as when sugar is split into alcohol and carbon dioxide.
Often these operations are accompanied by the development of a foul-smelling gas,
when we speak of putrefaction. The number of saprophytic Bacteria which excite
characteristic splittings in their substrata is considerable. In addition to those
already quoted, we may mention Bacillus Amylobacter, the organism of butyric
acid fermentation; Bacillus lacticus, which causes milk to become sour; Leuconostoc
mesenterioides, which has the power of converting large quantities of sugar into a
gelatinous mass in a very short space of time. Again, in a number of forms. the
production of a special colouring matter is associated with the activity of the
organisms, as is the case with Micrococcus prodigiosus (cf. fig. 3681), the “blood-
portent” which makes its appearance on various starchy food-stufts, and Beggiatoa
roseo-persicina, found on decaying vegetable matter in water, and known as
“peach-mud”. Many Bacteria are parasitic in the bodies of animals, and some
among them are harmless. This is the case with Sarcvna ventriculi (fig. 3681),
known only in the human alimentary canal in the form of packets of cells. Harm-

624 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

less also are a number of Bacteria found on the mucous membrane of the mouth.
On the other hand, many are associated with definite diseases. Spirochete Ober-
meiert (fig. 368°) is found in the blood in great quantities during relapsing fever;
Bacillus anthracis (figs. 3687 and 368%) causes anthrax in cattle, &c.; and a great
many other diseases—diphtheria, cholera (figs. 368° and 368 °), tuberculosis, leprosy,
&c.—are associated with the activity of specific bacterial organisms. Nor must we
omit to mention the numerous forms which occur in the soil, some of which are
concerned in the process of nitrification, 1.e. which oxidize ammonia into nitric acid,
thus rendering this source of nitrogen available to higher plants, whilst others

~ /
SN®
on 5) 7
‘@ uns oe
F AIK ®
ay \\Ge
my Ny SS
i .

Fig. 368.—Bacteria.

1 The “‘blood-portent,” Micrococcus prodigiosus. 2 Zoogloea-form of same. % Bacterium acett. 4The same more highly
magnified, 5 Spirochcete choleree asiatice. 6 The same more highly magnified. 7 Bacillus anthracis and red blood-
corpuscles. ® The same more highly magnified. % Spirocheete Obermeieri and red blood-corpuscles. 10 Sarcina ventriculi.
1, 2, 4, 5,7, 9 x 300; 10 x 800; 4 6 8 x 2000.

actually fix free nitrogen, as is the case with the organism occurring in the root-
tubercles of many leguminous plants (ef. p. 521). There is no doubt this organism
(Rhizobiwm, as it has been called) can store up free nitrogen, and that leguminous
plants, when associated with it, obtain nitrogen not to be accounted for as combined
nitrogen obtained from the soil. Curious also is the activity of the sulphur and
iron Bacteria. The former (eg. Beggiatoa alba) have the power of reducing the
sulphates contained in the waters which they inhabit and of storing up sulphur-
grains in their protoplasm; whilst the latter (e.g. Crenothria Kihniana), not
uncommon in water-pipes, where they often develop in enormous quantities, store
up iron in the gelatinous sheaths of their filaments.

That Bacteria existed in former times, and were then, as now, the agents of
decomposition, seems probable in view of the condition revealed by residues of dead

THALLOPHYTA. 625

plants in the coal measures. It is thought that Bacillus Amylobacter has been
identified in a silicified state.
Of living Bacteria a very large number have been distinguished.

Class I1.—DINOFLAGELLATA, Peridinex.
Alliance IV.

This compact group of unicellular organisms is, as has been said above, a
branch of the Flagellate Protozoa. They have therefore no very near affinities with
other plant groups, though the nutrition of many is thoroughly plant-like. They
would come nearest to the motile (Flagellate) forms of Protococcoidez (see p. 628).

The great characteristic of the group is the possession of two flagella, one directed
longitudinally and attached to the anterior end of the body, the other transversely
directed and often situated in a circular transverse groove. There is sometimes also
a longitudinal furrow. It is this transverse flagellum which is specially concerned
in movement.

There is often a cell membrane of cellulose, and the cell possesses green or
brownish chromatophores containing chlorophyll and a single large nucleus.

Reproduction is effected by binary fission, usually during a resting stage of the
cell.

Most of the forms are marine, and some are the cause of sea-phosphorescence.

The group is divided into two sections—the Adinida without, and the Dinifera
with a transverse furrow.

Ceratvum and Peridinium are two well-known genera.

Class ITI.—BACILLARIALES.,
Alliance V.

Family: Diatomacee, Diatoms.

These are a large group of unicellular plants which grow both in fresh and salt
water and upon moist soil. As a rule they occur together in large numbers. The
protoplasm is coloured brown by a brown pigment, diatomin, which masks the
chlorophyll which is also present. The colouring matter is restricted to special
chromatophores, which may be few or numerous. The cell-wall is incrusted with
silica, and is a very characteristic feature of the Diatom. The wall consists of two.
halves or valves (frustules) which fit into one another like the lid on to a pill-box.
These valves are smooth or variously sculptured, dotted, ribbed, &., and enjoy a
wide popularity as microscopic objects on account of the beauty and delicacy of
their tracery. Some idea of the variety and form of Diatom-cells may be obtained
from the accompanying figure 369. In the colonial forms the cells are attached
to the substratum directly (fig. 3691) or by means of branching filaments (fig. 369 “*).
Others are attached to one another in zigzag chains or continuous ribbons (figs.

369 and 369%), Others, again, are embedded in mucilage. Many of the forms
Vou. ID. 90

626 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

exhibit a curious creeping movement, which is explained as being due to an
external sheath or to filaments of protoplasm; the median line (or “raphe ”) shown
by certain forms (e.g. Navicula, fig. 869 *) is interpreted as a narrow slit at which
this external protoplasm is extruded. Diatoms propagate by continuous longitudi-
nal division; the valves are slightly separated, and division takes place parallel to
the faces of the valves. Each daughter-cell thus possesses one of the valves of the
mother-cell, and they complete their integument by secreting another on the side
away from it. The new valve is always slightly smaller than the other one and

2 3 17

WS

MS

CNN
UT i

We

TM

Fig. 369.—Diatoms.

1 Several individuals of Synedra Ulna attached to a cell of an aquatic plant. 2A single individual of Synedra Ulna more
highly magnified. %and4 Navicula Liber, seen from the side and from in front. 5 and ¢ Similar views of Navicula
tumida. 7 Triceratium Favus. 8% Campylodiscus spiralis. 9% Pleurosigma angulatum. 10 and 11 Grammatophora ser-
pentina. 12 and 18 Two views of Gomphonema capi 14 Gomph ypi on branched stalks which are
attached to some algal filament. 15 Diatom vulgare; the cells hang together into a zigzag band. 16 and 1’ Fragillaria
virescens, showing an individual from two aspects and a row of six joined together into aribbon. 18 Cocconema Cistula.
19 Two individuals of Cocconema Cistula inclosed in a mucilaginous envelope preliminary to auxospore-formation. 2 The
two auxospores have elongated, and the old cases are seen to right and left; there is no conjugation in this instance. All
highly magnified.

fits under its rim, so that the Diatoms arising in this way become smaller and
smaller till a certain minimum is reached. When this diminution has gone on for
a certain period an enlargement is attained by the formation of what are termed
aucospores. The contents of the cell gather themselves together, they become free
from. the valves, enlarge, and then put on new valves. In other cases an actual
conjugation takes place, two individuals uniting into an auxospore; or each may
divide into two daughter-cells, which fuse in pairs, forming two auxospores. Fig.
369” shows two cells of Cocconema Cistula embedded in mucilage previous to
auxospore-formation; in fig. 369° each cell has escaped from its valves, and has
doubled its original length. In this instance, however, there is no accompanying
conjugation.

Diatoms are very widely distributed over the globe, and occur in quantities in

THALLOPHYTA, 627

the surface layers of the sea; some 30 species have been found amongst the inor-
ganic dust of the snow-field. There are some 2000 species of living forms.

Considerable deposits of Diatoms occur in various parts of the world; of these
the most remarkable is that of Richmond, Virginia, U.S.A. It is said to extend for
many miles and to be 40 ft.deep. They are found in secondary, tertiary, and more
recent rocks. Siliceous marl consists entirely of the tests of Diatoms. A block
of such a Diatom-deposit some two cubic feet in bulk from a fresh-water lake in
Australia is exhibited in the Botanical Department of the British Museum; the
number of Diatoms contained in it (there are 21 different species) is estimated as
exceeding 12 billions (12 x 10”),

Class IV.W—GAMOPH YCEA,

Sub-class I.—Cutoroppycsa, the Green Alege.

There can hardly be a more fascinating group of plants than this, whether to
‘the strictly scientific botanist or to the more catholic lover of nature. In the first
place, the Green Algz are among the most widely diffused of plant-forms. They
grow practically in every place where enough moisture, together with light and air,
are to be had. Between tide-marks on almost every coast, floating on the surface of
the deep sea, covering damp earth, walls, palings, and tree trunks, sticking to the
surface of leaves in the moist atmosphere of tropical forests and jungles, and
inhabiting almost every river, brook, pond, ditch, or casual pool of rain-water in all
quarters of the globe, are members of this ubiquitous group to be found. Nor are
they wanting from more extraordinary situations. In Switzerland, Norway, and
other countries where snow is more or less permanent, the bright red patches on its
surface, known as “red snow”, are formed by the microscopic Alga (Spherella niva-
lis) shown in Plate I of the first volume. Other forms, not so far removed from
Spherella, live in the intercellular spaces of higher plants, such as the Ivy-leaved
Duckweed (Lemna trisulca), the Moneywort (Lysimachia nummularia), and
others. Yet other Alge are found inhabiting the jelly of certain fresh-water
sponges in the East Indies, where they seem to live in a regular symbiosis with
their hosts. But perhaps the most curious dwelling-places of all are the hollow
hairs of the Three-toed Sloth (Bradypus tridactylus), which are inhabited by an
Alga called Trichophilus.

In the second place, many of the Green Algz (and among these some of the
very commonest) are the most beautiful forms of life imaginable, and the main
features of their structure canbe made out with quite low powers of the microscope.

But perhaps the greatest claim on our interest is made by the fact that we must
look among the Green Alge not only for indications of the origin of all plant life,
and of the forms from which the whole of the higher plant world arose, but also for
hints towards the solution of some of the most difficult and fundamental problems
with which Biologists are occupied, questions as to the real nature and origin of
sexual reproduction, as to the distinction between gametes and asexual reproduc-

628 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

tive cells, as to the physiological conditions which determine their formation, and
finally, questions as to the division of labour in the protoplast itself, the function
of the nucleus and its relation to the protoplasm, and how far the latter can be
resolved into separate, but mutually co-operative parts.

The framework of our knowledge on the former group of questions has been, and
is being, built up largely from a study of the Green Algz; of the latter—and even
more fundamental—we know, as yet, very little, but the same group of plants is
already beginning to yield important results, and we have every reason to expect
an even richer harvest in the immediate future.

We shall now proceed to a brief review of the groups into which the Chloro-
phyces may be divided, mention being made of the more interesting forms in each
group.

The sub-class Chlorophycee may be defined as follows:—Thallus of very various
form, one- or many-celled, coloured green by chlorophyll which is contained in
chromatophores of very various shape: the green colour rarely masked by other
pigments. Reproduction by motile zoospores, and by gametes, which either resemble
small zoospores, and are equal in size (1soplanogametes), or are differentiated into
two categories; first, relatively small, active male gametes—called spermatozoids
when they are very highly differentiated—and secondly, relatively large, passive
female gametes—known as eggs or oospheres when they are quite passive. The cell
produced by the fusion of the bodies of two gametes is called the zygote, and gives
rise to a new plant either mediately or immediately. When the gametes are
sexually differentiated, the zygote (now called a fertilized egg or oospore) is pro-
duced only by the fusion of a male with a female gamete.

Other reproductive cells are known as aplanospores and akinetes. Aplanospores
are formed by the protoplasm of a cell of the thallus rounding itself off and putting
on a new cell-wall, or dividing into several parts, each of which acquires a separate
cell-wall. Akinetes are simply single cells of the thallus, whose original walls
thicken directly, the cells becoming separated from the rest of the thallus. These
two categories of reproductive cells germinate at once to form new plants. The
Chlorophyce comprehend the following alliances:—Protococcoidee, Siphonee,
Confervoidex, Conjugatze, and Charales.

Alliance VI.—Protococcoider.

Families: Chlamydomonadec, Volvocece, Pleurococcaceee, Endospheracee,
Hydrodictyacee.

Unicellular forms, actively swimming, floating, or fixed in habit, living either
singly or united into colonies.

Family Chlamydomonadew. This family consists of minute green (sometimes
red) organisms which spend the greater part of their life actively swimming about
in water. Several species of the genus Chlamydomonas are very common in
stagnant water. Each Chlamydomonas-cell consists of a roundish mass of proto-

THALLOPHYTA. 629

plasm covered by a delicate cell-wall of cellulose. At first sight the whole body
appears green, but on careful examination it will be seen that the green colouring-
matter is really confined to a layer on the surface of the body. This chlorophyll-
layer or chromatophore is specially thickened at one end (the posterior end) of the
body, and a small, clear, spherical body (the pyrenoid) is often to be seen inclosed
in this thickened portion. Round the sides of the body the chromatophore is
thinner, and towards the anterior end it stops, leaving a small area of colourless
protoplasm to occupy the front extremity of the organism. This is in connection
with another small mass of colourless protoplasm which occupies the hollow of the
cup-shaped chromatophore.

A minute red speck is visible at one side of the body, situated sometimes on the
surface, sometimes at the limit between the chromatophore and the central colour-
less protoplasm. The rotation of the Chlamydomonas about its antero-posterior
axis, which accompanies the jerky, forward movement (cf. vol. i. p. 29) can be well
traced by the aid of this eye-spot, which can be seen to be carried round and
round as the organism turns on its axis. The means by which the Chlamydomonas
moves are not at first sight apparent. But when the cell has come to rest, and
especially if it has been killed and its protoplasm fixed with a dilute solution of
iodine, a pair of very delicate protoplasmic filaments, called flagella, can often be
seen projecting from the colourless anterior spot of protoplasm. It is by the con-
tinual lashing of these flagella that the Chlamydomonas is pulled through the
water. The iodine will also bring into view a small sphérical nucleus, stained dark
brown, situated in the colourless central protoplasm, and will stain the neighbour-
hood of the pyrenoid a dark blue. This last phenomenon is due to the formation
of starch by the protoplasm round the pyrenoid. The exact part played by the
pyrenoid is very obscure, but there can be no doubt that it influences in some way
the formation or deposition of starch by the protoplasm.

The movements of Chlamydomonas are often in direct relation to light, the
organisms moving towards a source of light of moderate intensity. Thus if a glass
vessel filled with water containing Chlamydomonas be placed in a sunny window,
there will be a general movement of the swarming cells to the sunny side of the
vessel, causing the water to become much greener on that side. There is some evi-
dence that it is the eye-spot which enables the organism to perceive the direction
from which light is proceeding. Nearly all the motile Protococcoidez, as well as
zoospores and gametes which are sensitive to light, possess an eye-spot, and it has
been thought that the eye-spot-pigment (a substance called hematochrome) may act
in the same way as the visual purple in the retina of the eye.

If specimens of Chlamydomonas be kept for a day or two in water, some of them
will often be found to have divided to form daughter individuals, which still remain
inclosed within the cellulose membrane of the mother. This division is preceded by
the drawing in of the flagella. The protoplasm of the body then withdraws itself
from the wall, and divides transversely to form two roundish masses.. Each of the
latter may either at once put on a cell-wall and develop flagella, or it may divide

630 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

again, so that four daughter individuals instead of two are formed. Eventually the
daughters escape from the membrane of the mother, leaving it quite empty.

The process of reproduction by simple division of all the protoplasm of an indi-
vidual’s body into parts, each of which forms the body of a daughter individual, is
an example of almost the simplest type of reproduction known. It is true that in
the lower Protozoa, which have no rigid cellulose membrane, we find an even simpler
type. Since the entire organism consists of protoplasm, there is nothing left of the
parent individual after division has taken place. The body of the parent simply
becomes the body of the offspring. In the type of Chlamydomonas we have the
dead cellulose membrane representing all that is left of the body of the parent. In
many of the higher Alge, and in all plants above the level of Thallophytes, only a
part of the protoplasm of the plant-body is used in the formation of the reproductive
cells. The rest must then eventually die. But in these lower forms, where all the
protoplasm of the body is used in the production of new individuals, death, as a
necessary event, can hardly be said to occur.

Gametes are formed in Chlamydomonas in exactly the same way as daughter
individuals. They are, however, smaller and have no cell-wall. In one species at
least the gametes are of two sizes. Of the smaller (microgametes) eight are produced.
from a parent individual, while only two of the larger size (megagametes) are formed
from the parent cell. In the process of conjugation a microgamete and megagamete
come into contact at their anterior colourless ends, the flagella are drawn in, and a
thick cellulose membrane is secreted round the bodies of both. The protoplasm of
the microgamete then passes over into the space inclosed by the part of the mem-
brane belonging to the megagamete, and completely fuses with the protoplasm of
the latter. A wall is then formed, cutting off the empty shell of the microgamete.
The contents of the zygote eventually divides to form two or four new individuals
which escape from its membrane. In the conjugation of most species where there
is no distinction in size between the gametes, a cell-wall is only acquired after the
foundation of the zygote. This is the regular course of events in the conjugation of
the motile gametes of Green Alge.

The genus Spherella resembles Chlamydomonas in the fundamental points of its
structure. The main distinction is the existence of a considerable space separating
the membrane from the main body of the protoplasm of Sphewrella. This space is
bridged by fine strands of protoplasm, which radiate from the central mass and end
in fine branches under the membrane. The anterior colourless protoplasm is drawn
out into a beak, and to the extremity of this the two flagella are attached. The
flagella often pass through two very delicate cellulose tubes, which in the common
species, S. pluvialis, diverge from the extremity of the beak, and end on either side
at the membrane. In another species (S. Biitschlii) the beak runs right up to the
membrane, and the flagella-tubes, which are short and slightly curved, lie on the
outer surface of the membrane. ‘

Spherella plurals is a very well-known microscopic object, being extremely
common in pools of rain-water. Its protoplasm often contains a good deal of the red

THALLOPHYTA, 631

pigment hematochrome, which may almost completely mask its green colour. It
was from this circumstance that it received its name of Hawmatococcus pluvialis.
Hematochrome is even more constantly present in Sphwrella nivalis, the “red snow”,
whose appearance and life-history have already been described (vol. i. p. 39). 8S.
Bitschlia has its hematochrome concentrated in an eye-spot like that of Chlamy-
domonas.

The Volvocece differ from the Chlamydomonadew in consisting of motile colonies
of cells, the members of each colony being united in a common investment. The
bodies of the individuals composing the colony are also joined in some genera by
protoplasmic processes. The body of each individual is identical, in the fundamen-
tal points of its structure, with that of a Chlamydomonas or of a Spherella. The
Volvocece present us with an interesting series of forms, showing a gradually increas-
ing sexual differentiation of gametes, and, in the higher forms, an interesting sub-
ordination of the individual to the colony as a whole.

Gonium is a form in which the colony consists of (usually) sixteen Chlamydo-
monas-like cells arranged in a flat plate, which swims in a line at right angles to
its surface, the flagella of the central cells of the dise projecting forwards, those of
the peripheral cells obliquely outwards and forwards. All the cells are inclosed in
a general mucilaginous envelope, and are joined to one another by protoplasmic
processes.

Reproduction is effected by the division of the constituent cells of the colony in
two planes at right angles to one another and to the plane of the colony, so that each
mother colony produces sixteen daughter colonies, whose dises of cells all lie in the
same plane. Meanwhile, the mother cells are separated from one another by the
gradual liquefaction of the general mucilaginous envelope, and thus the daughter
colonies become independent.

Formation of isogametes also takes place, but is not thoroughly understood.

Stephanosphera is a very beautiful form, occurring especially in pools of rain-
water collected in rock hollows in hilly districts. It is often found in company with
Spherella pluvialis. The colony consists of a ring of (usually) eight Spherella-like
cells arranged in the equatorial plane of a spherical or ovoid cellulose membrane.

When reproduction is about to occur, the constituent cells draw in the protoplas-
mic processes by which they are attached to the general membrane; each secretes a
membrane of its own, and then its protoplasm divides in two planes to form eight
(sometimes seven) daughter-cells. When these have acquired flagella they begin to
swarm, and eventually escape by bursting the membrane of the mother colony.

Gametes are formed in the same way, but usually by more divisions, as many as
thirty-two being sometimes produced from a single cell. In most cases all the cells
of a colony divide at once to form gametes, but this is not invariably the case.
Each bundle of gametes produced from a single cell breaks up, and all the gametes
begin to swarm within the colony. The gametes are spindle-shaped, each with two
flagella and an eye-spot. They conjugate in pairs, usually inside the general mem-
brane, but conjugation never takes place between two gemetes derived from the

632 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

same mother cell. The actual process of pairing has been fully described, and it
may be taken as a type of the course of events, as it has been observed in all Alge
with isoplanogametes whose pairing has been fully investigated. Out of the crowd
of gametes swarming in all directions, two approach and stroke each other with
their flagella; in some cases the two separate and both become again lost in the
crowd, but, when pairing is going to take place, they become firmly fixed together
by their colourless anterior ends. The long axes of their bodies may then lie in one
straight line, or may diverge at a wide angle. A rotation of each of the pairing
gametes about its fixed anterior end now always occurs, the bodies becoming gradu-
ally approximated, so that their long axes come to lie nearly parallel. Fusion of the
protoplasm follows, beginning at the already joined anterior ends, and progressing
rapidly backwards till a single mass of protoplasm is formed. The four flagella still
move actively, and the Zygozoospore, as this active type of zygote is often called,
escapes from the general membrane of the mother colony, becomes spherical by
shortening of its long axis, loses its flagella, and puts on a cell-wall. The protoplasm
soon loses its green colour, becoming reddish, and the zygote enters on a resting
period. Eventually its protoplasm divides, producing zoospores, each of which gives
rise to a new colony.

The division of the cells of a colony to form zoospores or gametes begins in the
evening, and is finished soon after sunrise. In dull weather, however, its comple-
tion is delayed far into the day. This dependence of the formation of zoospores
and gametes upon the influence of light, if not invariable, is found very widely
among the Green Alga.

Pandorina is a fairly common form in ponds, &c. The colony consists of
sixteen wedge-shaped cells arranged in a sphere, and covered by a general invest-
ment, which is of considerable density at its external surface. The apex of each
wedge is directed towards the centre of the sphere, and there is little space left
between the adjacent cells. The formation of daughter-colonies is similar to that
obtaining in Goniwm and Stephanosphera. The young colonies escape by liquefac-
tion of the investing membrane. Colonies of gametes are formed in the same
way, but often consist of eight instead of sixteen cells, and the acquirement of
flagella and liquefaction of the mother membrane takes place more slowly. Event-
ually the membrane of each gamete-colony also becomes liquefied, and most of the
gametes swarm out into the water. A great number of mother colonies of different
sizes simultaneously take part in this production of gametes, so that the water
becomes filled with masses of swarming gametes of very variable dimensions. No
distinct size-categories are, however, to be distinguished. Conjugation now takes
place between pairs of gametes either of the same or of different sizes; with this
exception, that the largest gametes do not fuse with one another. They are rela-
tively inactive, sometimes, indeed, remaining fixed in their colonies, and are sought
out and paired with by the smaller and more active individuals. Here, then, we
have a most interesting stage in the evolution of sex. The largest, relatively
passive, gametes may fairly be called female, while the different sizes of smaller

\

THALLOPHYTA. 633

gametes, though sexually differentiated inter se, since conjugation is apparently
possible between any two, whatever their relative size, may perhaps be considered
as male in relation to the largest.

It is probable that fully-differentiated male and female gametes arose from
forms such as we find in Pandorina, by the suppression of the intermediate sizes,
the smaller and more active gametes taking on the function of actively seeking out
the larger passive individuals, which on their side contribute practically the whole
of the stock of food required by the zygote in germination. In correspondence with
this we find the chromatophore (chlorophyll-corpuscle), which may be considered as
the specially food-producing organ of the algal cell, much reduced and eventually
functionless or absent altogether in the more highly differentiated male gametes
(spermatozoids).

Eudorvna has a colony of sixteen or thirty-two almost spherical cells consider-
ably separated from one another, and inclosed in a general investment like that of
Pandorina. In the production of daughter-colonies Eudorina resembles the lower
forms of the volvocine series, but in the sexual differentiation of the gametes there
is a decided advance upon that obtaining in Pandorina. The perfectly passive
female gametes (oospheres) hardly differ from the ordinary cells of a vegetative
colony, while the active male gametes (spermatozoids) are formed in bundles of
sixty-four by successive divisions of similar cells. Here, then, we find the marked
difference in size between the two categories of gametes brought about, as it very
often is among the Algz (and, indeed, among many other plants and animals), by a
marked difference in the number of divisions occurring in their respective mother-
cells. The present case in which strictly comparable cells on the one hand directly
give rise to eggs, and on the other divide to form sixty-four spermatozoids each, is
rather extreme, but we have already met with a similar case in a species of
Chlamydomonas.

Each spermatozoid of Hudorina is club-shaped, with a colourless pointed
anterior end bearing two flagella and possessing an eye-spot, and a yellowish thick
posterior extremity representing the (reduced) chlorophyllous portion of the typical
volvocine cell. The spermatozoid bundle (male colony) escapes from its mother-cell-
membrane, and swarms as a whole towards a female colony. On reaching the latter
the spermatozoids get their flagella, become entangled in the thick mucilage, and
rapidly separating from one another, worm their way into the female colony. Some
succeed in fusing with the individual female gametes, and each zygote thus formed
will eventually give rise to a new Eudorina colony.

A form recently discovered almost at the same time in three different States of
North America, and known as Pleodorina, shows an important difference from the
‘ypes we have hitherto been considering. Each spherical colony consists of about

* 28 cells, but not all of these are capable of producing daughter-colonies, This
ower is confined to those cells which occupy the posterior half or two-thirds of the
sphere (it should be explained that the colony moves forward in relation to a
iefinite axis). The smaller anteriorly-placed cells are thus purely vegetative in

634 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

function, and necessarily die after the reproductive cells have given rise to daughter-
colonies. This is the first time we have met with such natural death among the
Algz, and it is very clearly seen to be connected with the separation of the assimila-
tive and reproductive functions. The formation of gametes in Pleodorina has
unfortunately not yet been observed.

The remarkable and beautiful organism called Volvow has been known for more
than two centuries, and has long been among the most favourite of microscopic
objects. The purely scientific interest which it has aroused has been as great as
the «esthetic admiration which it has excited. Long and animated controversies
have raged on the question as to whether it was to be regarded as an animal or a
plant, as an individual or as a colony of individuals. And although these ques-
tions have now lost much of their actuality through the gradual recognition by
naturalists that we have absolutely no criteria by which they can be settled, there
have arisen problems which promise quite as much interest and excitement for the
future.

Volvoz is much larger than the forms hitherto described. The colony is
spherical, and possesses a single layer of cells on its surface. In V. Globator the
sphere may be over a millimetre in diameter, but more usually its diameter is only
some three-quarters of a millimetre. A particularly large specimen may possess as
many as 22,000 cells (10,000 is a more usual number). Many of the cells, however,
as in Pleodorina, are simply vegetative, and take no part in the reproduction of
the colony. Usually, in fact, only a very small minority of the cells are repro-
ductive.

The two species of Volvow differ from each other in a great number of points,
but we have only space for a very brief description of some of the most interesting.

The cells of Volvow Globator are all united together by very stout processes.
Each cell, which is inclosed in a separate cell-wall, possesses all the ordinary features
of the Chlamydomonas type.

Daughter-colonies are developed from special cells, usually eight in number,
called parthenogonidia. They are always formed in the posterior part of the
mother-colony, early becoming larger than the ordinary vegetative cells. Each
divides repeatedly, and forms a hollow sphere of closely-packed cells, which, after
the last division, mostly acquire the characters of the adult vegetative cells, the
remainder gradually increasing in size to form the reproductive cells. The young
colonies then escape from the mother, apparently by pushing themselves against
and making rents in its posterior wall. Subsequently the cell-membranes swell a
good deal, separating the cell-bodies from one another, and the colony attains its
adult size.

In other cases gametes may be formed in a young colony. About five celis
(androgonidia), strongly resembling the parthenogonidia, divide to form dises or
hollow spheres of a hundred or more spermatozoids. The spermatozoids resemble
in a general way those of Zudorina, but are peculiar in having the pair of flagella
inserted laterally at the base of the colourless beak and near the eye-spot. In the

THALLOPHYTA, 635

same colonies, but a little later than the androgonidia, about thirty much larger
spherical cells, the oospheres, are developed, and these are duly fertilized, but by
spermatozoids derived from another colony. The zygote has a sculptured exine.
Parthenogonidia are not found in those colonies which produce gametes.

Volvox awreus (= V. minor), the commoner form, is usually much smaller than
V. Globator, and has rounded cells more widely separated and connected by very
delicate processes. But perhaps its most striking characteristic is the very great
variability in the number and distribution of the reproductive cells. The partheno-
gonidia, which vary in number from one to sixteen, may either occur alone or in
one colony with androgonidia or oospheres, or both. Most of the sexual colonies
are dicecious, though this is not always the case. The colonies containing androgo-
nidia unaccompanied by other reproductive cells often develop very numerous (up
to 1100) spermatozoid bund’es, the androgonidia forming one-third of all the cells of
the colony. The spermatozoids differ from those of V. Globator by their larger size,
by their terminal flagella at the end of a shorter beak, and by the possession of a
well-developed leaf-green chromatophore. We must, therefore, consider V. aureus
as not so highly developed, in some respects at least, as V. Globator.

A Volvox-colony always swims in the direction of a given axis passing through
its body, and at the same time rotates to the right or left about an axis which is
inclined obliquely to the antero-posterior axis. The eye-spots of the vegetative cells
are much better developed in the anterior half of the colony, and are always
situated on the side of the cell nearest the anterior pole. These facts tend to
support the view of the function of eye-spots in general suggested above.

Volvox stands at the head of the series of colonial (ccenobe-forming) organisms
which we have been tracing, a series diverging from a Chlamydomonas- or Sphe-
rella-like type, and whose successive forms gradually increase in size, complexity,
and sexual differentiation. Volvow itself has been well spoken of as “ the culmina-
tion of Nature’s attempt to evolve a higher organism out of a ecenobe”. It was an
attempt which failed, or rather which could not be carried any further than Volvox
itself. A delicate, easily-ruptured Volvox-sphere could certainly not continue to
exist if it were much more than a millimetre in diameter. As it is, the wall is often
split, and all sorts of smaller organisms get inside, resulting in the more or less
speedy collapse of the Volvox-colony.

. But there are other series diverging from the Chlamydomonadex, and some at
least of them have followed lines on which it was possible for higher and more
varied plant-forms to be developed.

At the first stage along one of these lines of descent we find ourselves among
forms in which the dominant phase of the life-history falls in a resting stage, either
fixed or freely floating in the water. From this resting stage motile forms (zoo-
spores), corresponding with the free-swimming Chlamydomonas individuals, are
directly developed. These zoospores, after a short period of swarming, come to rest,
often fixing themselves by their anterior end to some solid object. With little or
no change in the constitution and appearance of the cell the main portion of the

636 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

life cycle is passed in this fixed condition, and cell divisions take place, the products
eventually again developing flagella and being set free as zoospores. The genera
Chlorangiwm and Physocytiwm ave examples of the simplest form of this type of
life-history. Forms with a rather more complicated structure in the fixed stage are
found in the genera Mischococcus (a common form on the surface of threads of the
higher Algee), Euglenopsis (a newly-discovered American plant), and their allies
In these the protoplasm of the zoospore, after fixing itself and putting on a delicate
cell-wall, pushes out the surface of its membrane away from the substratum, thus
forming a tube of gradually increasing length, the apex of which is always occupied
by the protoplasm. Division of the protoplasm and subsequent pushing out of the
wall of the tube in different directions by the daughter-cells results in a branching
of the hollow stalk, and in this way quite a considerable branching plant-body
may be produced. Eventually some or all of the cells occupying the apices of the
various branches of the tube acquire flagella and escape into the water as zoospores,
which again settle on solid objects and give rise to new plants.

Other forms in which the cell derived from a zoospore multiplies by division, the
products eventually again giving rise to zoospores, are Schizochlamys, Botryococcus,
Dictyospheriwm and Tetraspora. In these, however, the immotile phase is not fixed,
but forms floating colonies of various conformation. Into this topic we cannot
enter further, except to remark that Tetraspora forms flat colonies of cells arranged
in one plane and held together by the swollen mucilaginous cell-walls. Cell division
takes place in planes at right angles to that of the colony. This type of colony is
specially interesting, as it suggests the form of thallus found in Ulvacew, which in
turn appears to lead on to the higher forms Confervoiden.

Plewrococcacec.—More or less closely allied to the above-mentioned genera are
others which do not form zoospores at all. These types with no motile phase in
their life-cycle may be conveniently classed together as Pleurococcacecw. The type-
genus Plewrococcus contains some of the most widely-distributed algal forms known.
P. vulgaris forms the bulk of the green coating of damp earth, tree trunks, palings,
&c., in all regions of the globe. It consists of roundish cells, dividing in three direc-
tions in space and thus forming solid masses of cells hanging together in multiples of
two, and often flattened by lateral contact. Each cell contains several parietal chro-
matophores which may, however, fuse together to form a single one. Resting aki-
netes are formed by the cells ceasing to divide, becoming spherical, and thickening
their walls. At the same time oil appears in the protoplasm. It is probably mainly
in this phase that Plewrococeus gets distributed by the wind from one place of growth
to another. Owing to the resemblance of the akinetes of some of the confervoid
Algee to those of Plewrococcus, it has often been stated, and indeed is still held by
some algologists that Plewrococcus itself is merely a growth-phase of these higher
Algw. But recent culture-experiments leave little room for doubt that Plewrococcus
is a perfectly autonomous form, although it may often be associated with pleurococcoid
stages of other Alge. Hremosphera is a pretty form, common in fresh water, with
single floating spherical cells. Each cell contains numerous separate chlorophy]ll-

THALLOPHYTA, 637

bodies, embedded in a parietal layer of protoplasm, and a nucleus suspended by
protoplasmic strands in the centre of the cell. Multiplication is effected by division
of the protoplasm into two daughter-cells which escape by rupture of the mother-
cell membrane. Scenedesmus is another motionless floating fresh-water form. It
consists of oblong cells united into groups of two, four, or eight, which lie side by
side, palisade fashion. Some or all of the cells often possess straight or horn-like
projections of their walls, which give the cell groups a very characteristic appear-
ance. The single solid chromatophore occupies nearly the whole cell cavity. Chlo-
rella is a genus whose cells are symbiotic with Radiolaria (yellow cells). Other
forms live in a similar relation with certain Ccelenterates and Platyhelminths.
Several help to form lichens. Since the various genera of Plewrococcacee differ
thus very widely in the form and structure of their cells, and indeed are only united
by the negative character of the absence of zoospores, it is almost certain that they
cannot be considered as forming a natural group. The various genera are very
probably allied to different neighbouring groups from which they have been derived
by the suppression of the habit of forming zoospores.

The Endospheracee are a small and very natural group of unicellular Alge,
characterized by their habit of living in the intercellular spaces of various higher
plants. They possess motile zoospores, or gametes, or both, but the motionless cells
produced from these do not undergo vegetative divisions. Very possibly they
represent a separate line of descent from the Chlamydomonadese, a line of descent
in which the motionless cell has become the dominant phase in the life-cycle, and
has been specially adapted to the new conditions of life, but differs from the motion-
less cells of the “ Tetrasporacee ” in directly forming zoospores without undergoing
purely vegetative divisions.

Two forms of Endospheraces may be taken as illustrations of this type of life-
history.

Chlorochytrium Lemne inhabits the intercellular spaces immediately under the
epidermis of the leaves of Lemna trisulca (the Ivy-leaved Duckweed). Each plant
consists of a single, thick-walled, oval cell with a parietal chromatophore containing
numerous pyrenoids and a large central vacuole. Very numerous pear-shaped
isogametes are formed by successive divisions of the protoplasm of the cell. Then
a layer of substance outside the mass of gametes (probably the ectoplasm of the
cell) begins to swell strongly, and bursts not only the cell-wall but also the super-
incumbent tissue of the Duckweed leaf, forming a sphere of mucilage in which the
gametes begin to swarm and to conjugate in pairs. Spherical zygozoospores are
thus produced; these escape from the mucilage, and after some free swarming in
the surrounding water, settle on the boundary between two epidermal cells of a
Duckweed leaf, draw in their flagella, put on a cell-membrane, and form a definite
parietal chlorophyll-body with a single pyrenoid. After two or three days a delicate,
colourless tube is put out, which forces its way between the two epidermal cells of
the leaf, and reaches an intercellular space. The contents of the zygote slowly pass
over into the apex of this tube, which gradually increases in size and assumes the

638 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

characters of a young vegetative cell, the original zygote-wall remaining on the
surface of the leaf as a mere cellulose knob.

The generations rapidly succeed one another during the summer months, the
last-formed cells of the season becoming packed with starch grains and passing the
winter in this state. These resting cells can withstand desiccation, in case the pond
in which the duckweed lives becomes dried up.

Phyllobium dimorphum forms large immotile cells between the tracheids of
the vascular bundles in the leaves of the creeping Moneywort (Lysimachia
nummularia). This plant lives in damp woods and other shady places. The Rhine
plain in the neighbourhood of Strasburg, where Phyllobiwm was first found in the
leaves of the Moneywort, is usually flooded during the month of June, partly by
the rising of the river, and partly by the thunderstorms which usually occur about
that time of the year. The Phyllobiwm-cells take this opportunity to form their
gametes, which are of two distinct sizes, each cell producing gametes of one size
only. After the escape of the gametes into the surrounding water conjugation
occurs. The zygozoospores produced have only two flagella, the body and flagella
of each microgamete being completely lost in the megagamete, just as the body of
a spermatozoid is completely lost in the substance of the egg. After coming to rest
on the surface of a Lysimachia leaf, and acquiring cell-membranes, the zygotes put
out delicate tubes which enter the stomata of the leaf. If a leaf is infected by a
few zygotes only, the tubes formed reach the vascular bundles, and forcing their
way between the elements of the wood, grow forward in the bundles, branching
when they branch, and attaining to a considerable length. Eventually, towards the
end of the summer, the protoplasmic contents of each tube becoming concentrated
in one spot, this part of the tube swells and is cut off from the remainder by the
formation of transverse partitions. The swollen part of the tube thus forms a large
cell which rests during the winter, and in the next summer will produce gametes.
If, on the other hand, the leaf is infected by a large number of zygotes, most of the
tubes never get any further than the intercellular spaces immediately under the
stomata. In this position they form small resting cells in large numbers. These
eventually form zoospores, which apparently behave, on germination, just like the
zygozoospores. The dimorphism of the resting cells of Phyllobiwm thus depends
directly on the amount of space at the disposal of the germ tubes. This conclusion
can be confirmed by cultivating the germ tubes apart from the leaves of the host.

The purpose of the germ tubes of Chlorochytriwm, Phyllobiwm, and their allies
in penetrating the leaves of their hosts, seems to be simply that they may gain the
advantage of a quiet protected place for their development. Just in the same way
Diatoms and other unicellular forms often live comfortably in the empty cells of
Algz, the intercellular spaces of the Bog-moss (Sphagnum), and similar situations.
Only in the case of these Endospherew the association of the Alga with its habitat
is invariable and adaptive, not merely casual and unrelated. But the Endospheerese
are not parasites in any sense. They take no food from their “hosts” nor do they
exercise any appreciable influence on the latter. This is sufficiently proved by the

THALLOPHYTA, 639

fact that Lemna trisulea lives quite happily and can flower when infested with
Chlorochytriwm, and that the germ tubes of Phyllobiwm dimorphwm usually enter
dead leaves of the Moneywort. Another form which always enters the living leaves
of a river-weed, continues its course of development whether the leaves die or re-
main alive. It is not, however, difficult to imagine how a form like Phyllobiwm,
living as it does in the vascular bundles of its host, might acquire a parasitic habit
by tapping the food supplies. As a matter of fact certain confervoid Algw are
known whose presence results in the death of the leaves they inhabit, though pro-
bably not by direct appropriation of the food of the host.

Resembling the Zndospheree in possessing motionless cells which form zoospores
but do not undergo vegetative divisions, are certain common fresh-water forms of
which Characiwm and Sciadiwm may be mentioned. A plant of Sciadiwm ori-
ginally consists of a single cylindrical cell whose contents breaks up into zoospores.
These zoospores have acquired the peculiar habit of settling on the rim of the
mother-cell, instead of seeking out fresh spots for their development. Each zoospore
produces a single cell like the mother, so that a whorl of cells of the new genera-
tion is formed on the top of the original cell. This process may be repeated for
two or three generations, after which the zoospores will settle on some other object
and start fresh “plants”.

The Hydrodictyacee are a group of Algew which form immotile colonies. The
cells of these colonies resemble the single cells of the forms we have just been con-
sidering in producing zoospores or gametes, but undergoing no vegetative divisions.
The colony is formed by the joining together in a definite way of the group of
zoospores formed in a single cell of the mother-colony. Each of these zoospores
then develops into an adult vegetative cell.

The recently discovered genus Huwastropsis (so called from its likeness to the
Desmid Euastrum) is the simplest type of the family. It consists of two mitre-
shaped cells joined to one another by their bases. Each cell contains a parietal
chromatophore with a single pyrenoid, and a single nucleus. The contents breaks
up by successive divisions into 2-32 zoospores, which escape from the cell surrounded
by a general membrane. After oscillating for about a quarter of an hour, the zoo-
spores become attached in pairs by their anterior ends. Each pair then takes on
the characters of the two-celled colony.

Pediastrum (fig. 370°) consists of a disc of cells, of which the marginal ones are
often drawn out into lobes or processes. The chromatophore is parietal with a
single pyrenoid; there are numerous nuclei. The formation of zoospores is like that
of Euastropsis, but their movement is more lively, and eventually all the zoospores
formed in a single cell join together to form a new Pediastrum-colony (figs. 3707
and 370°). Gametes are formed in the same way as the zoospores, but are smaller
and more numerous. They escape from the investing membrane, swim freely in
the water, and fuse in pairs to form zygotes. From these zygotes new Pediastrum-
colonies are produced indirectly, probably by a method like that obtaining in
Hydrodictyon.

640 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Hydrodictyon, the Water-net (figs. 3701 and 3702) is a beautiful organism
forming net-like colonies of cylindrical cells, which are joined end to end, forming
the sides of the polygonal meshes. Each cell may be as much as 1 centimetre in
length. A thin layer of protoplasm containing numerous small nuclei lines the
wall and incloses a large central vacuole. The chromatophore, or chlorophyll-layer
of the protoplasm, contains many pyrenoids, each surrounded by a sheath of starch
grains. Fine-grained starch is also scattered through the substance of the chro-

Fig. 370.—Hydrodictyacee.

1 The Water-net (Hydrodictyon utriculosum), nat. size. 2A portion of the same magnified 50 diameters. 8, 4, and 5 Formation
of zoospores in a cell of Hydrodictyon, showing their union together, and escape as a young net; x 300. 6 Pediastrum
granulatum; development and escape of zoospores, the lightly-dotted chambers already vacated. 7 and § Zoospores after
their escape arranged as a new Pediastrum plant; x 240.

matophore. This stroma-starch appears in great quantity when growth is checked
and assimilation remains active, disappearing again if assimilation is stopped. The
pyrenoid-starch, on the other hand, seerhs to be withdrawn from the ordinary meta-
bolism of the cell, since it is formed round each pyrenoid early in the life of the
cell, and remains there under all circumstances, unless the cell is on the point of
actual starvation in the dark, till the onset of reproduction. When zoospores are
about to be formed the pyrenoids together with their starch disappear, and abund-
ant stroma-starch appears. At the same time the nuclei multiply a good deal by
division, and eventually the whole of the protoplasm divides to form a great num-

THALLOPHYTA. 641

ber of zoospores. These zoospores, however, never become free like those of Pedi-
astrum, but remain joined together by strands of protoplasm, and after a certain
amount of shifting backwards and forwards, come to rest with their ends in contact.
Each then gradually assumes the characters of a Hydrodictyon-cell, the young
colony eventually escaping from the mother-cell (figs. 370% 45), Gametes are formed
in the same way as zoospores, but are smaller and more numerous. The spherical
zygote gradually increases in size, and its contents breaks up into 2-5 large zoo-
spores, which develop into large cells with pointed processes, the so-called poly-
hedre. In the interior of each polyhedron an embryonic Hydrodictyon-net is
developed from swarm-spores, and in the cells of this ordinary Hydrodictyon
colonies are found.

It has been shown experimentally that any Hydrodictyon not above a certain
size and age is capable of producing either zoospores or gametes, and that the
stimulus to the formation of one or the other is given by external conditions.
Thus bright light, fresh water rich in inorganic nutritive salts, and fairly high
temperatures, are favourable to the production of zoospores, while the reverse of
these conditions, and especially the presence of organic substances, such as sugar,
tend to make the cells of a net produce gametes. The conditions favourable to
zoospore-formation are also of course, favourable to active vegetative growth,
and no doubt the abundant formation of new protoplasm is a necessary preliminary
to the production of zoospores. A slight check to the processes of assimilation and
growth is apparently necessary in order to give play to the zoospore-forming forces.
Thus, experimentally, a change from a strong solution of nutritive salts to fresh
water will induce the formation of zoospores in nets which would simply have gone
on growing if left in the nutritive solution. A similar check is probably given by
the waning light in many Algz in which zoospores are produced at night. For the
production of gametes, on the other hand, an actual reversal of the conditions
favourable to growth is necessary. In nature this probably happens when by very
active growth the whole of the water of a pool is filled with nets, the inorganic
food and oxygen are exhausted, and the normal chemical processes of the cell
receive a check. The formation of gametes and zygotes under these conditions is
obviously adaptive, since the zygote can, although it need not, rest during several
months till the conditions are quite altered. We may therefore conclude that,
whereas zoospores are especially designed to multiply and distribute the species,
zygotes are intended to preserve it under unfavourable conditions. It is probable
that the production of large zoospores and polyhedra is a necessary part of the
life-cycle following the germination of the zygote, and cannot be altered by the
incidence of different conditions.

Alliance VII.—Siphonee.

Thallus consisting of a tube, often much branched, and containing many nuclei.
‘This tube is the production of a single cell, but in the more complicated forms is

often shut off into compartments by transverse septa. Reproduction hy Zosspores
Vou. II.

642 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

and planogametes, or spermatozoids and eggs: in very many forms no reproductive
cells are known. The higher forms of Siphonew often produce plant-bodies of very
definite and characteristic external form, and of considerable size. In some cases
these simulate the external form of various higher plants.

Families: Botrydiacee, Phyllosiphonacee, Vawcheriacece, Bryopsidacee,
Caulerpacee, Codiacee, Valoniacee, Verticellate.

Botrydiacece.—Botrydium granulatum is a little plant found growing espe-
cially on loam at the damp edges of ponds and ditches. It consists of a club-shaped
or balloon-shaped green shoot-portion, about 1-4 millimetres in diameter, continuous
with a simple or branched tubular colourless root-portion which is embedded in the
substratum. The entire plant consists of a single cell, that is to say, its cavity is
continuous throughout. The wall is lined with a thin layer of protoplasm, which
contains many nuclei, and, in the shoot, a net-like chlorophyll-layer.

Botrydium can reproduce itself in very various ways, according to the incidence
of external conditions. The simplest form of propagation is by budding, which
takes place under conditions favourable to the ordinary vegetation of the plant.
The shoot-portion of a small vegetative plant sends out a process which swells to
the size of the mother shoot, puts out a colourless root, and is then constricted off
to form a separate plant. But if the plants are covered with water they cannot
go on growing comfortably, and accordingly the protoplasm breaks up to form a
number of zoospores, each with a single flagellum and two lateral chromatophores.
The mass of zoospores is subjected to considerable pressure by the swelling up of a
ring-like area of the wall, and the tension becomes so great as to rupture the wall
in the centre of the ring and expel the mass of zoospores into the water. On damp
soil the zoospores come to rest, and germinate to form new plants. If a zoospore
cannot escape from the water it enters on a resting stage, which gives rise to a new
plant directly it finds itself on damp soil. Further, if a young plant is exposed to
bright sunlight, its protoplasm breaks up into a number of spherical cells, each of
which puts on a cell-wall. If now these spherical cells (gametangia) are placed in
water, the contents of each breaks up into spindle-shaped, biflagellate gametes,
which conjugate in pairs to form zygotes. These zygotes can rest for a longer or
shorter time, but if placed on damp earth they at once germinate to form new
plants. If, on the other hand, the gametangia are placed in water after being kept
for two years they give rise to biflagellate cells which rather resemble the gametes,
but which on damp soil germinate directly to form vegetative plants. Finally, if
the gametangia are at once placed on damp soil, their contents does not break up,
but the whole gametangium germinates and produces a plant. Supposing a large
Botrydiwm-plant, with a balloon-shaped shoot, be exposed to insolation (bright
light) its contents, instead of forming gametangia, travels down into the root, and
the protoplasm there divides to form rows of root-cells, each with an independent
cell-wall. If a root containing root-cells be placed in water, the protoplasm of each
cell breaks up into a number of zoospores: if the root be placed on damp earth each

THALLOPHYTA. 643

root-cell sends out a tube which grows into a young vegetative plant: if left in the
soil, the latter remaining damp, each root-cell germinates to form a peculiar thick-
walled plant called a hypnosporangiwm which can withstand desiccation, and which
in water gives rise to a number of zoospores.

The above facts may be briefly expressed by saying that any stage in the life-
history of Botrydiwm tends (1) on damp soil to form vegetative plants, (2) in water
to form zoospores or gametes, (3) in dry conditions to form resting cells. There
can, then, be no doubt that here, as in the case of Hydrodictyon, we are justified in
saying that the form which any given set of conditions tends to produce is adapted
to meet those conditions.

Phyllosiphonacece.—Phyllosiphon Arisari is an Alga living in the intercellular
spaces of the leaves of Arisarum vulgare in Southern France and Italy. Its
thallus consists of a much-branched tube, the parietal protoplasm containing many
nuclei and small disc-shaped chromatophores. Unlike the Hndosphwrew, the pre-
sence of Phyllosiphon has a considerable effect on its host, causing blotches of dead
tissue to appear in the leaves. As the Alga can presumably assimilate quite well
for itself, this destruction of tissue is probably caused by withdrawal of water from
the cells of the host. The only kind of reproductive cells which Phyllosiphon is
known to produce are aplanospores (non-motile spores). These are formed by the
division of the whole of the protoplasm of the thallus. They are extruded by the
swelling of the inner membrane of the tube which bursts the outer membrane just
under a stoma, shooting out a jet of mucilage in which the aplanospores are em-
bedded. The latter germinate directly, the germ-tubes entering the leaf between
two epidermal cells.

Vaucheriacece—This family includes only the well-known and widely distri-
buted genus Vaucheria. Different species of Vawcheria grow in brackish and fresh
water, both running and stagnant, or in the air in damp situations. The thallus
consists of relatively coarse branched tubes, quite visible to the naked eye. The
interior of the tube is lined by a layer of protoplasm containing numerous disc-
shaped chlorophyll-grains and many nuclei. The Vaucheria-plant is fixed to
its substratum by short-branched, colourless processes, but, except in connection
with the formation of reproductive cells, transverse septa are not formed in the
tubes.

The gametes of Vaucheria are formed in special organs, known as antheridia
and oogonia. The distinction of sex is very strongly marked, the male gametes or
spermatozoids being very small oval cells, each with two laterally inserted flagella,
while the female gametes or eggs are very large and quite motionless. The
antheridia are often spirally curved branches of the main tube, a transverse wall
separating the upper part of the spiral, the antheridium proper, from the lower part,
which is continuous with the cavity of the vegetative tube. Sometimes, however, the
antheridium is straight and club-shaped, and in other cases it may be separated
from the main tube by an intermediate cell. The thirty-five species of Vaucheria
are classified according to the characters of their antheridia. The oogonia are

644 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

ovoid or spherical, and usually possess a lateral beak. While the antheridium pro-
duces a large number of the small spermatozoids, the oogonium gives rise to a
single large egg. An account has already been given of the process of fertilization
(see p. 58, and figs. 204° and 204°, on p. 53).

Vaucheria also produces peculiar zoospores, whose development and subsequent
behaviour have been described on pp. 23 and 24 of vol. i. (see Plate L a-d). The
cilia with which the surface of the zoospore is clothed are arranged in pairs, and in
the colourless external layer of protoplasm just below each pair of cilia is situated a
single nucleus. This suggests that the zoospore of Vaucheria is to be regarded as
really equivalent to a great many zoospores which have not separated during
development, each nucleus, with its pair of cilia and a certain amount of chloro-
phyll and protoplasm, representing an ordinary zoospore. It has been found that
if, as often happens, the zoospore breaks into two during its struggles to escape
from the end of its tube, the front part rounds itself off and swims away, behaving
just like an entire zoospore. In some species of Vawcheria the zoospores are
only partially clothed with cilia and come to rest soon after their escape. In yet
others they have no cilia at all, and either escape by dissolution of the end of the
tube, or germinate im situ. Here then we have a transition from the formation
of active zoospores to the production of passive aplanospores.

The occurrence and form of reproduction is here even more entirely under the
control of conditions than is the case in Hydrodictyon. The age and size of the
plant are no longer factors, since sexual organs and zoospores can be formed on
quite short germ-tubes. Cultivation of the plant in a solution rich in inorganic
food-salts always gives it a tendency to produce zoospores, but the immediate
stimulus to their formation is given by a distinct change in the conditions, just as
is the case in the Water-net. In Vaucheria this change is especially necessary,
since each zoospore is formed in the apex of a tube, and apical growth must be
stopped in order to allow free play to the zoospore-forming forces.

The nature of the change, so far as regards the medium, is apparently im-
material—it may be a change from running water to still water, or from a damp
atmosphere to water, or in the temperature or concentration of the culture-solution,
but it is a change from light to darkness which is especially effective. This is quite
contrary to the case of Hydrodictyon. The presence of water and a temperature
between 3° and 26° C. are absolutely necessary conditions ef zoospore-formation.

The former condition is obviously adaptive. The formation of sexual organs
is specially induced by the replacement of inorganic salts by organic substances (e.g.
sugar), just as in the case of the gametes of Hydrodictyon, but antheridia and
oogonia, which are formed much more frequently and easily than are the Water-net
gametes, often appear in the presence of salts, and when growing in a damp atmos-
phere. Light and a temperature above 3° C. are absolutely necessary conditions.

The most striking point in the physiology of the reproduction of Vaucheria is
the prominent part played by the sexual organs. These are undoubtedly the princi-
pal means of propagation the plant possesses, the zoospores, which usually fulfil this

THALLOPHYTA. 645

réle, having fallen to a subordinate position. Only in forms like Vaucheria clavata,
adapted to life in rapidly-flowing water, have the zoospores a primary importance.
Sexual reproduction is here difficult, and zoospores are always produced in abun-
dance on the slightest change of conditions.

Bryopsidacece.—This family consists of marine, mostly tropical, forms. The
plant-body of Bryopsis has quite a definite form, and consists of a tube forming the
main axis, fixed below by short root branches, and bearing above in acropetal suc-
cession a series of branches, some of unlimited, some of limited growth. In these
latter are formed swarming cells which are of two sizes, the smaller being yellowish,
while the larger have each a green chromatophore. It seems very probable that
these are anisogametes, but their conjugation has not been observed.

Derbesia is a genus like Bryopsis in many respects, but with special zoosporangia
which produce curious zoospores, each with an anterior crown of cilia.

Caulerpacece.—The genus Caulerpa contains nearly one hundred species, which
present the most varied external forms, simulating those of many of the higher
plants, such as Mosses, Ferns, Mare’s-tails, Cactuses, Conifers, &. Each plant, how-
ever, consists simply of a single much-branched but uninterrupted tube, the branches
taking the forms of roots, leafy shoots, &c. The tube is supported internally by a
complicated system of “beams” of cellulose which run out from the walls.

The Caulerpas live mainly in tropical and subtropical seas. They often grow
together in large masses, forming great beds of sea-weed, their creeping stems or
“rhizomes” extending many yards. No reproductive cells have as yet been found
in any of them, multiplication taking place apparently solely by the breaking off of
parts of the thallus, which drift and fix themselves elsewhere.

Codiacee.—Under this name we may conveniently place together a group of
forms specially characterized by a thallus consisting of richly-branched tubes, which
are interwoven to form a mass of more or less solid character, which possesses in
each genus a definite and characteristic external conformation. Thus, Penicillus has
a long cylindrical “stalk” fixed below by “rhizoids” and bearing above a head of
free dichotomously branching radiating filaments. The older parts of the stalk are
strongly incrusted with calcium carbonate.

Udotea has a stalk often creeping and branching, bearing flat fan-shaped
fronds. Spherical bodies, the nature of which is unknown, are borne on short side
branches of the tubes of which the frond is built up. Halimeda possesses a thallus
mainly composed of series of heart- or kidney-shaped segments, which give many of
the species the appearance of an Opuntia. There is usually a considerable deposit
of calcium carbonate covering the thallus. Roundish structures, produced in grape-
like bunches on the edges of the segments, liberate swarming cells whose behaviour
has not been followed.

Codiwm has no well differentiated stalk or segments; the thallus is very various
in form, and is differentiated into a well-marked pith and cortex, the tubes being
mainly longitudinal and loosely packed in the former, while the latter consists of
club-shaped closely-packed branches arranged at right angles to the surface. In

646 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

certain branches of the latter swarmers of two sizes are produced. Analogy would
lead us to suppose that at least the smaller of these are gametes, but their behaviour
has not been observed. Some species of Codiwm (e.g. C. tomentosum, with a dichoto-
mously branched furry thallus) occur on our own coasts. The remaining Codiaceze
are largely tropical, but very widely distributed.

Valoniacece—We may include in this family an assemblage of genera whose
thallus consists of a branching tube, usually forming transverse walls, but with no
interweaving of the branches such as we get in Codiacez.

The simplest type is found in Valonia, a form which at first consists of a single
club-shaped cell, which produces a whorl of branches at its upper end. Each of
these may again produce a whorl of branches of the second order.

A group of very beautiful genera form leaf-like structures, the branching of the
thallus taking place in one plane. Struvea consists originally of a single cell, which
grows apically and becomes divided by transverse walls into a series of segments.
Each of these segments bears a pair of branches coming off right and left, and each
branch behaves like the main axis. The secondary and tertiary branches thus pro-
duced come into contact, fixing themselves one to another by means of curious little
rosette-like organs called tenacula, and the whole thus forms a net-like structure
with larger or smaller meshes between the branches. The definite usually oval form
of the “leaf”, of which the main axis forms the midrib, and the primary branches
the principal veins, is due to the latter, after they have attained a certain length,
ceasing to produce branches on the side towards the base of the thallus, and at the
same time bending forwards and inwards to join the primary branch next in front.

Struvea delicatula sometimes lives in the tissue of a Sponge belonging to the
genus Halichondria. There is a reciprocal effect on the form of the two organisms,
the Alga only taking on the characteristic Strwvea-form when part of its thallus.
grows out clear of the body of the Sponge. In consequence of this it was for some
time not suspected that this sponge-inhabiting Alga had any connection with
Struvea. Neither organism seems to suffer from the association, and there is some
evidence for regarding it as a case of true symbiosis.

Anadyomene is another very beautiful form resembling Struvea in the construc-
tion of its thallus, but with no meshes between the cells. It consists of two kinds
of cells, the more elongated form the “ribs” of the thallus, the smaller and more
rounded make up the intermediate tissue.

The genus Boodlea, in which the branching takes place in more than one plane,
forms a transitional form connecting these genera with Cladophora, which is usually
regarded as belonging to the Confervoides.

Verticillate.—In this group of the Siphonee the thallus consists of a long
cylindrical undivided stalk, fixed below by rhizoids, and bearing above acropetal
whorls of simple or branched appendages of limited growth. In some of these
appendages gametes may be produced; zoospores are apparently absent. It includes
two sub-families, the Acetabularies and Dasycladee.

Acetabulariece.—Fertile and sterile appendages distinct. Acetabularia mediter-

THALLOPHYTA. 647

ranea: the lower part of the long cylindrical stalk is incrusted with calcium car-
bonate, and fixed to its substratum by short irregularly branched rhizoids. The
rhizoid-bearing portion is called the foot, and below it there is a thin-walled branched
continuation of the stalk, called the basal division. Near the apex of the stalk are
borne 1-4 whorls of polychotomously branched sterile appendages, which soon
fall off.

Above these is an umbrella-shaped whorl of simple appendages in lateral contact,
whose cavities are not shut off from that of the stalk. The whole of the upper part
of the plant dies off each autumn, only the foot and basal division remaining alive
through the winter. In the spring a new shoot is produced. Apparently after
several years the contents of each simple appendage of the umbrella (which may
now be a centimetre or more in diameter) divides up into a number of oval bodies,
each surrounded by a fairly thick wall and containing chlorophyll and starch.
These are the gametangia. After their escape by the dissolution of the umbrella,
the contents of each divides up to form a number of gametes. Considerable pressure,
caused by swelling of the ectoplasm and osmotic tension in the vacuole of the game-
tangium, bursts off a lid at one end, and the gametes escape. Conjugation only
occurs between gametes derived from distinct gametangia.

Dasycladece—No distinction between fertile and sterile appendages. Dasycladus
has a single stalk-cell fixed below like Acetabularia, but bearing very numerous
whorls of appendages, which stand so close together as to give the entire plant
a resemblance to a minute fox’s brush. Each appendage bears a terminal whorl
of branches, and in the middle of these is a shortly-stalked, nearly spherical
gametangium. The gametes conjugate, but apparently only with those from
certain other plants. This fact at first led to the supposition that we had here
a physiological distinction of sex in gametes, which in external appearance are all
alike. This is, however, quite an unjustifiable and unnecessary assumption. We
have no right to predicate sexual differences between gametes which do not show
any of the well-recognized characters of male and female reproductive cells. The
tendency to avoid pairing with closely related gametes, which we may call exogamy,
is quite a distinct phenomenon, not only among isogamous Alge, but also among
many of the higher plants, where it coexists with strongly-marked sex. The pheno-
mena of self-sterility is an extreme case of this.

Neomeris and Cymopolia are two tropical and subtropical genera, whose thallus
is very strongly incrusted with calcium carbonate. -The arrangement of the
branches resembles that found in Dasycladus, but on the ends of the younger ones
hairs are borne, which serve to protect the growing apex of the plant. In Cymo-
polia, of which the main stalk branches, and the thallus attains a considerable size,
these hairs are borne by simple branches produced on special constricted and uncal-
cified zones of the stalk. The apices of the secondary branches are in both genera
swollen up, and in close lateral contact, thus forming a continuous surface on the
exterior of the plant. The calcium carbonate is deposited as a thick layer under-
neath these swollen ends.

648 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

A whole series of fossil forms from the chalk and tertiary deposits serve to con-
nect the various existing types of these and allied genera.

Alliance VIII.—Confervoider.

The Alge included under this alliance possess a type of thallus composed of dis-
tinct and separate cells. These cells are united usually into linear series, which form
branched or unbranched threads. In a few families, however, cell-division takes
place in two, or even three, dimensions, resembling the Protococcoides in the forma-
tion of cell-surfaces or cell-masses. Zoospores are produced by nearly all confervoid
forms. Aplanospores and akinetes are common, The gametes may be isogamous,
or they may show marked sexual differentiation.

Families: Ulvacee, Ulotrichacee, Cylindrocapsacee, Cdogoniacee, Clado-
phoracee, Gomontiacee, Spheropleacee, Cheetophoracee, Trentepohliacee, Mycot-
deacece, Coleochatacece.

Ulvacece.—This family is usually regarded as the lowest of the confervoid series.
It is characterized especially by forming cell-surfaces instead of filaments. Zoo-
spores with four flagella and isogametes with two, as well as allimetes, are
formed in the group. Monostroma very much resembles Tetraspora among the
Protococcoides, from which we may suppose the confervoid forms to have arisen
in evolution. The thallus consists of a single layer of roundish or angular cells. In
germination, the zygote divides to form a small hollow sphere, which splits, and
extends itself to form a flat plate. At first fixed by rhizoids, the thallus later floats
freely in the water. The chromatophore is a parietal plate, covering more or less of
the cell-wall, and contains a single pyrenoid. Gametes (which may develop without
conjugation), or zoospores may be formed in almost any cell of the thallus.

Ulva differs from Monostroma in possessing a thallus of two layers of cells,
those of each layer dividing independently of the other. The zygote germinates to
form a fixed cell thread, which later on produces the two-layered thallus. Ulva
latissima (the Green Laver or Sea-lettuce) is very common on the rocks of our
coasts near high-tide mark. It forms large green wavy fronds firmly fixed to the
substratum. It is sometimes used as an article of food.

Enteromorpha is a large genus, several species of which are common on our
coasts, and some in fresh water. The thallus forms a branched hollow tube, the
wall of which is one cell thick. Any cell of the thallus may act as the apical cell
of a branch. The apex of the branch is solid, but the cells soon round themselves
off to form the wall of the tube. The gametes and zoospores resemble those of
Monostroma and Ulva.

Litterstedtia is a Cape and Australian form much like Ulwa, but with a deeply-
lobed thallus. Zoospores are produced only in the cells of the lobes.

Ulotrichacece.—This family contains several genera common in fresh water, and
some marine forms. The thallus consists of an unbranched filament of cells seldom
much longer than they are broad. The chromatophore is single, parietal, and of

THALLOPHYTA. 649

very various form. Zoospores are formed in most genera. Gametes, where known,
are motile and isogamous. Aplanospores and akinetes are very commonly formed,
under unfavourable conditions.

Ulothria (fig. 871), the best-known genus, possesses cells of very variable length.
The chromatophore, which contains several pyrenoids, is an interrupted cylinder,
and may or may not occupy the whole length of the cell. When the conditions are
suddenly changed, zoospores or gametes are very readily formed, the former 1-4
the latter 4-32 in a cell. According to the size of the mother-cell and the number
of divisions taking place, the size of the zoospores and gametes varies greatly, the

Fig. 371.—Ulothriz zonata,

1 Two filaments of this plant. 2 Escape of gametes in packets. 2 Spherical packet of gametes free from the filament. 4Separa-
tion of the gametes. 5 Gametes swimming about and pairing. 6 Products of pairing of gametes (zygotes) attached to
substratum, 7-9 Zygote giving rise to zoospores. 1° Two zoospores. 1x 250; 2-10 x 400. (Partly after Dodel-Port.)

only constant distinction between them being the number of flagella, which in the
zoospores are four, in the gametes two (cf. figs. 871!° and 371°). The zoospores or
gametes escape from the mother-cell through a hole in the wall. They are surrounded
by a bladder derived, probably, from ectoplasm. The swelling of this in the water
helps to drag them out of the cell-cavity. The tension of the vacuole of the mother-
cell, which is visible among the zoospores or gametes as a smaller bladder, also assists
in pressing out the mass (figs. 371%**). The zoospore settles on some solid object,
and, after putting out a short root-process from its colourless anterior end, produces
a new cell-thread. Some of the gametes develop parthenogenetically, in which case
they germinate just like zoospores, but produce usually smaller and weaker plants.
The gametes which conjugate (see figs. 871° and 371°) produce zygotes which sink
to the bottom of the water, and after a period of rest grow into unicellular plants,
each of which forms 2-14 zoospores (figs. 371%7%°). These probably give rise te
ordinary plants.

650 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

The asexual generations of Ulothrix are produced during the autumn and
winter, gametes being formed in spring, and the zygote resting through the summer.
This course of events differs from that obtaining in most Algew with a similar life-
history. Ulothria seems especially adapted to life in cold water.

Hormidiwm is a genus whose members grow largely on damp earth, tree trunks,
&e. The chromatophore is solid, with radiating processes and a central pyrenoid.
The cells of some species divide longitudinally, so as to form threads two cells
broad.

Various other genera are common in fresh water.

Cylindrocapsacee.—Cylindrocapsa forms unbranched threads of short cells with
very thick walls, each thread being fixed in the young state by a cellulose foot.
The gametes show a considerable sexual differentiation. The males are pear-shaped,
elongated, yellow, with two flagella at the anterior end. They are produced two in
an antheridium, which is formed by the division of an ordinary cell into two or
four. The protoplasm of an ordinary cell rounds itself off directly to become an
egg, the wall swelling and bursting at one side to allow of the entrance of the
spermatozoids. Parthenogenesis also occurs.

Edogoniaceee.—Gdogoniwm has a thallus consisting of an unbranched thread,
of rather long cells, of which the basal one is fixed to some solid object. The
chromatophore often forms a continuous parietal layer containing several pyrenoids.
All the cells, except the basal one, are capable of division. When division is going
to occur a rim of cellulose is formed inside the cell close to the upper transverse
wall. After the nucleus has divided, and the new transverse wall is formed, the rim
is opened, as it were, by a circular cut from without, and the tension of the cell
causes a pulling-out of the substance of the rim. The result is the intercalation
of a new cylindrical piece of cell-wall in the upper daughter-cell. The young
transverse wall now moves up to the lower edge of the intercalated piece of mem-
brane. The latter soon acquires the ordinary thickness of a side wall, but the
segment of the old cell-wall above the spot at which the rim was formed remains
projecting beyond the new piece like the eaves of a house beyond its side walls.
After the cell has divided again, another projecting piece will be left in the same
way, and the series of eave-like projections so formed are a very characteristic
feature of the cells of an @dogoniwm-thread. The zoospores of Edogoniwm are
formed singly in the cells of a thread. The entire cell-body, with the exception of
the ectoplasm, rounds itself off and escapes from the cell by a split in the wall.
An anterior circlet of cilia surrounds the colourless “mouth place,” of the zoospore.
In germination, the zoospore fixes itself by the mouth place, sending out short fixing
processes, puts on a cell-membrane, and then grows out to form a new thread.

The gametes of @dogonium are sexually differentiated.

The oogonium is formed by the swelling-up of the uppermost daughter-cell after
a division. The contents round off to form a single large oosphere. Either a round
hole appears in the wall, or a circular split is formed at the upper end of the
oogonium, the part of the filament above rotating through a few degrees so as to

THALLOPHYTA. 651

leave an opening. A certain amount of the protoplasm of the oosphere is extruded
at this spot, and forms a sort of canal of mucilage, through which a spermatozoid
passes in fertilization. The spermatozoids are produced one or two in an anther-
idium, which are short cells poor in chlorophyll, formed by the repeated division of
certain cells of a thread. The spermatozoids resemble small zoospores. In some
cases they are not produced directly from the cells of a thread, but the latter give
rise to special zoospores called androspores, which escape and settle either on or in
the immediate neighbourhood of an oogonium. The androspore then germinates,
producing a small structure called a dwarf male. This consists of a very few cells,
one or more of which become antheridia, and opening by a lid, gives rise to sper-
matozoids, one of which pierces the canal of the oogonium, and fuses with the
oosphere. The oospore, which is of a red or brown colour, produces four zoospores
in germination.

Bulbochete is a genus resembling Edogonium in its life-history, but consists
of a branched thread, only the basal cell being capable of dividing. The cells
bear characteristic hairs, swollen at the base, whence the name of the genus.

Species of Hdogoniwm and Bulbochete, which are both genera of considerable
size, are found in our ponds and ditches.

The next three families are distinguished from all other Confervoidee by pos-
sessing more than one nucleus in each cell.

Cladophoracece.—Cladophora is a very widely distributed genus, inhabiting both
fresh and salt water. A great number of species have been described, but it is
doubtful whether many of the forms are entitled to specific rank.

The thallus has a very characteristic habit. It is fixed below by an elongated
basal cell, and is profusely branched, sometimes forming a spherical mass. The
elongated cells possess parietal chromatophores, which cover the whole cell-wall,
and possess many pyrenoids. Sometimes the chlorophyll-layer is separable into
distinct angular plates. There are many nuclei in the layer of protoplasm imme-
diately within the chlorophyll.

Many zoospores are produced in each cell. The nuclei divide a good deal, the
pyrenoids disappear, and the protoplasm then divides into a number of separate
masses, each of which forms a single zoospore with either four or two flagella.
Gametes with two flagella are formed in many species quite like the zoospores.
The zygote germinates directly to form a new Cladophora-plant.

The Cladophoraceze show on the one hand a transition to the Siphonez, and on
the other, through certain genera with unbranched thallus and few nuclei in each
cell, to the Ulotrichacez.

Gomontiacee.—Gomontia polyrhiza is an isolated form which perforates the
shells of various marine molluscs, such as the whelk, the oyster, the mussel, &c.
The thallus radiates on the surface of the shell, and sends branches into the sub-
stance, gradually disintegrating it. Certain branches become zoosporangia or
aplanosporangia; these lose their attachment to the thallus and form fresh rhizoids.
The zoospores are pear-shaped, and germinate directly to form a new thallus.

1652 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Spheropleacec.—Spheroplea annulina is a curious Alga which appears occa-
sionally on flooded fields or in other situations. Its thallus consists of simple
threads of cells which are of very various length, sometimes enormously long. The
side walls are thin, but the transverse walls are often thick, and both are liable to
have curious thick and quite irregular projections of cellulose. The chromatophores
form irregular rings at intervals, and contain many pyrenoids. There are many
nuclei, and several variable vacuoles in each cell. All the cells may produce sexual
organs, the threads being either moncecious or dicecious. The contents of the cells
which become antheridia become yellow-red, and break up to form a great number
of elongated, pointed spermatozoids. These escape through small holes in the wall.
In the oogonia the protoplasm divides to form one or two series of spherical
oospheres, each with a colourless spot. The oospore has three membranes, of which
the outermost is folded so as to give the oospore a star-like appearance.

In germination the oospore produces 1-8 zoospores, which have a green posterior
and a pale-red anterior end. Each eventually stretches itself to form a spindle-
shaped cell, and a multiplication of nuclei and pyrenoids takes place before trans-
verse divisions occur and a new Sphceeroplea-filament is produced. Parthenogenesis
occurs, but apparently no zoospores are formed other than those produced in the
germination of the oospore.

Cheetophoracee.—This family contains forms with a branching thallus, the
branches often ending in fine hairs. The chromatophore is parietal, with one or
more pyrenoids. Zoospores with two or four, and gametes with two flagella are
produced.

Stigeocloniwm, Draparnaldia, and Cheetophora are three genera common in fresh-
water in this country, and all very slimy to the touch. In the first-named genus the
thallus is fixed by means of a basal disc of cells, the sole; the branching is simple
and irregular, the branches often ending in long multicellular hairs. Draparnaldia
shows a marked distinction between axis and appendages. The axial cells are
much larger, and at the same time poorer in chlorophyll than those of the branches.
The branches come off in bunches, and often end in many-celled hairs. The chro-
matophore possesses many pyrenoids varying in number according to the size of
the cell. Cheetophora possesses a thallus whose threads radiate and branch in all
directions. The whole is surrounded by a mucilaginous investment of considerable
firmness, sometimes almost leathery in consistence, so that a Cheetophora-plant has
the appearance of a slimy green ball.

There are several other genera belonging to this family, many of them being
epiphytic or endophytic. Entoderma lives in the cell-membranes of the Brown
Sea-weed Eetocarpus.

Trentepohliacew.—This family differs from the last in possessing no hairs, and in
forming its zoospores in special zoosporangia.

Trentepohlia is a fairly large genus containing forms mostly living in the air
on damp stones and similar situations. The thallus consists of rounded thick-walled
cells, and is dichotomously or irregularly branched, partly creeping, partly upright.

THALLOPHYTA, 653:

The chromatophores are many, disc-like, and angular, with no pyrenoids. The cell-
contents is usually much marked with hamatochrom. The zoosporangia and gamet-
angia are usually terminal, often swollen cells. The gametes and zoospores are
much alike. Trentepohlia Iolithus, growing on damp stones, is known as the
“Violet-stone ” from possessing a scent which recalls that of violets. 7. wmbrina is
often attacked by lichen-forming Fungi. 7. spongophila inhabits the jelly of
Ephydatia (Spongilla) fluviatilis in a certain volcanic lake in Sumatra. The
situation is very advantageous to the Alga, but the Sponge seems to suffer from
the piercing of its tissue by the guest. Trichophilus is a nearly allied form which
lives in the hollow hairs of the Three-Toed Sloth.

Mycordeacece.—These are epiphytic or parasitic forms nearly allied to the two
preceding families, and probably derived from one of them. They form regular
dises of cells often attached to the host by much-branched unicellular rhizoids. The
disc grows by regular divisions of its marginal cells. Zoospores and sometimes.
gametes are formed in all or some of the cells.

Cheetopeltis forms very regular discs of cells on fresh-water plants in Europe.

Mycoidea (Mycoidea parasitica) forms discs of cells between the cuticle and
epidermal cells of Camellias, Rhododendrons, &c. in the East Indies and South
America. In this position it withdraws a good deal of water from the tissue of the
leaf, and this leads to the dying of the leaf-cells in a gradually increasing area
round the parasite. Eventually a hole is formed right through the leaf, and the
Mycoidea-thallus occupying a position all round the area of dead tissue continues
to increase. Zoospores are only formed in the wet season, at which time alone have
they any chance of swarming and germinating on the surface of the leaf. In this
position primary (embryonic) discs are formed, many of which die, and others are
attacked by Fungi to form Lichens, but some succeed in sending processes through
the cuticle and establishing themselves below.

Coleocheetacee.—This family contains a single small genus, Coleochete, which
forms radiating, dichotomously branching rows of cells, usually on the surface of
other plants in fresh-water. If the cell-rows are in lateral contact, a close disc is
formed (C. scutata), if separate a looser one (C. soluta), or the branching may be
rather irregular (C. divergens). The chromatophore is parietal and disc-shaped,
and contains a single pyrenoid.

Zoospores can be produced in all or only the end cells of the rows. A single one
is formed from each cell. In germination a new plant is directly formed.

Coleocheete is oogamous, the plants being either moncecious or dicecious. The
oogonium is always formed from the end cell of a row. The cell swells and puts
out a narrow tube which opens at the end, and extrudes a drop of mucilage. The
protoplasm of the swollen basal part then rounds itself off. In the forms with a
dise-shaped thallus, the antheridia are produced by the division into four of the
members of certain cell-groups. Each daughter-cell (antheridium) then liberates a
single spermatozoid. In the branching forms certain end cells form flask-shaped
swellings (antheridia), which are cut off from the mother-cell by transverse walls.

654 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Each antheridium then liberates a spermatozoid. Fertilization has not been observed,
but there can be no doubt that a spermatozoid passes down the neck of the oogonium
and fuses with the oosphere. Subsequently the neck of the oogonium breaks off,
the oospore puts on a cell-wall, and the neighbouring cells branch so as to form a
closely investing cortex of cells round the oospore. The contents of these cortical
cells turn red-brown; and after a resting stage the cortex comes off, the oospore
having in the meanwhile divided to form a disc of cells, each of which gives rise to
a zoospore, which escapes and germinates to form a new plant.

The structure of the oogonium, and the formation of a cortex round the oospore,
as well as the formation of “carpospores” by the latter, recall the simpler Red
Sea-weeds, a group which some authorities consider to be derived from some form
like Coleocheete.

The indirect formation of new plants by the products of division of the zygote,
a phenomenon we have already met with in Pandorina, Hydrodictyon, Ulothria,
Edogonium, and other forms, is probably the means by which the sporophyte
generation of Mosses and Liverworts arose. At first the zygote gave rise at once
to spores, but later on a certain amount of sterile tissue was produced in addition,
and this formed the body of the sporophyte.

Alliance IX.—Conjugata.

Families: Desmidioidew, Spirogyracece, Zygnemacece, Mougeotiacece.

This is a very sharply characterized alliance of Green Algae. It is indeed
difficult to determine its affinities. The forms belonging to it are especially charac-
terized by never forming zoospores, and by possessing aplanogametes, 4. gametes
which, instead of escaping from the mother-cell and swarming freely, never leave
the cavities of the cells in which they are produced. When conjugation is about to
occur the two cells (gametangia), the contents of which will form gametes, approach
one another, and their walls come into contact, either directly, or by the putting out
from one or both cells of a short cellulose tube. The area of wall at the place of
contact breaks down, and the whole or part of the contents of each cell then fuses
with the corresponding protoplasm of the other to form a zygote.

The chromatophores of the Conjugate, though very various in the different
families, are all very different from the types met with among the other Green
Algee. 7

I. Desmidioidew. Cell-contents and outline symmetrically arranged on each
side of a given median plane which is often coincident with a more or less deep
constriction.. Often unicellular,

IL Zygnemoidee. Cells cylindrical, without median constriction, always form-
ing threads,

1. Spirogyracee. Chromatophores one or more, parietal, spiral,
2. Zygnemacee. Chromatophores two, axile, roundish,
8. Mougeotiacee. Chromatophore single, axile, plate-like.

THALLOPHYTA. 655

Desmidioidece—The Desmids are a large family of fresh-water forms numbering
over a thousand species. Perhaps their most favourite habitat in this country is
the water which collects and stands between mosses and similar plants on imper-
vious soils. Many of the Desmids are among the most beautiful of algal forms.

The great characteristic of the Desmid-cell is its almost invariable division into
two symmetrical halves, often separated by a circular constriction (cf. fig. 372).
The cell-membrane usually consists in fact of two distinct valves whose edges meet
in this median plane. In cell-division these two valves are forced apart, a new
cylindrical piece of membrane being intercalated between them. A transverse wall

Fig. $72. Desmids.

1 Micrasterias papillifera. % Micrasterias morsa. % Cosmarium polyg 4 Xanthide aculeatum. 5 Staurastrum
furcatum. § Euastrum oblongum, 7 Penium Brebi. ii. 8 Closterium Lunula. 9% Xanthidium octocorne. 1° Staur-
astrum alternans (two views). 11 Cosmarium tetraophthal 12 Aptog D tdi All the figures magnified

about 200 times.

is then formed at the equator, and each half of the new piece of wall gradually
assumes the characters of the old half-cell to which it belongs.

The actual form of the cell is very various; it is often lobed, and its wall
sculptured in various ways. A good idea of the shapes of some of the commoner
types can be obtained by an inspection of fig. 372; see also Plate i,k.

The chromatophores are also extremely various in form. A common type is an
axile rod bearing longitudinal plates which radiate in all directions. Each chroma-
tophore contains one or more pyrenoids. :

The cell-membrane is usually perforated by series of regularly arranged, very
minute pores which give exit to extremely delicate filaments of protoplasm. The
projecting end of each filament is surrounded by a mass of mucilage, and these
masses together form a complete sheath covering the entire cell, and sometimes even

656 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

groups of cells (¢f. similar phenomenon in Diatoms, p. 626). Many Desmids possess
the power of locomotion. Their movement is slow and creeping, and although the
means by which it is brought about are by no means fully understood, it has been
shown to have a connection with the excretion of mucilage, and to stand in relation
with light and gravitation. Some forms (e.g. Closteriwm and Penium, figs. 372°
and 3727) have a curious rotating movement, one end being temporarily fixed while
the other moves up towards the source of light.

Conjugation takes place as already described, the conjugating cells either
coming into direct contact, or putting out short tubes. The conjoined tubes are
known as the conjugation-canal. The zygote may be formed either in this or in
one of the conjugating cells.) The membrane of the zygote consists of three layers,
the outer one being sculptured in various ways. In germination, the outer, sculp-
tured membrane is burst open, and the protoplasm divides to form 2-8 cells which
gradually take on the characters of the adult individual.

The cells of the thread-forming Desmids (cf. fig. 872”) possess all the characters
of the unicellular types, the daughter cells simply remaining together after division
(which always occurs in one plane) has taken place.

Spirogyracee.—This family contains the single genus Spirogyra, many species
of which are amongst the commonest Algz in our ponds and ditches. They form
green or yellowish-green slimy masses on the mud at the bottom or’ floating at the
surface of the water. Such a Spirogyra-mass usually contains several species,
although the bulk of it is often formed by one.

The cells of the different species vary much in diameter, from the delicate S.
tenuissima which is only about one hundredth of a millimetre across, to S. crassa,
which forms coarse threads as much as one seventh of a millimetre thick. Roughly
speaking, the broader the cell, the greater number of chromatophores it possesses.
The smaller species possess only one spiral band in each cell (Plate I, 1), the largest
as many as eight or nine.

Each Spirogyra-cell is a cylinder, in most cases considerably longer than it is
broad (though the relation of length to breadth is variable even in one and the same
species), with a very delicate layer of protoplasm lining the wall, and a large central
vacuole. Each chromatophore forms a band embedded in the protoplasm, and
twisting spirally round and round the cell at an approximately constant angle.
When there are more bands than one they cross each other at regular intervals,
forming a beautiful lattice-work. In some species each band makes several com-
plete turns in its course down the cell (fig. 373); in others, it may be inclined at
such a small angle with the long axis that it makes less than a complete turn in the
length of the cell. In S. orthospira the bands are practically parallel with the long
axis, so that they do not follow a spiral course at all, but form straight bands.
Each chromatophore may be isodiametric, or, on the other hand, it may form a
flattened band. In the latter case its edges are usually irregularly scalloped. A
single row of pyrenoids at larger or smaller intervals is found in each chromato-
phore.

THALLOPHYTA. 657

Each cell contains a single nucleus which occupies approximately the centre of
the cell. In the larger species it is suspended in the middle of the vacuole by a
number of branching threads, many of which run into the peripheral protoplasm
opposite a pyrenoid. This can be particularly well seen in the large 8. crassa. It
suggests that the nucleus plays some active part in the function of starch formation.
In the smaller species when the breadth of the cell is perhaps not more than double
the diameter of the nucleus, the latter often lies in the concavity of, and in contact
with, a chromatophore. In this case the protoplasmic threads are not so obvious.

All the cells of a Spirogyra-thread are capable of division. After the nucleus
has divided, a rim of cellulose is secreted in the equatorial plane of the cell. This
is gradually added to from within, till a complete dise of cellulose is formed, sepa-
rating the two daughter-cells. Curious folds
are always formed on the transverse walls of
some species. Each fold forms a circular rim
near the periphery of the transverse wall and
projecting into the cell cavity. These folds are
sometimes completely evaginated, the transverse
wall thus having its surface considerably in-
creased and becoming strongly concave towards
the cell-cavity. This happens especially when
two cells are separating from one another, or,
when a gamete is formed from a neighbour-
ing cell.

Multiplication is often effected by the break-
ing up of a filament into segments consisting Fig. 873.—Spirogyra.
of a few cells each which go on dividing and Bie ait et a
form a new thread.

Conjugation takes place in two ways; a zygote being produced either from
gametes formed in two neighbouring cells of the same filament, or in two cells
belonging to distinct filaments. In the former case a small swelling is formed
opposite a septum, a small area of the septum breaks down, and the contents of one
cell, rounding itself off from the walls, passes through the aperture thus formed and
fuses with the contents of the other cell, also rounded off, to form a zygote, which
immediately puts on a membrane, and enters upon a resting stage.

In the second or “ladder-type” of conjugation (fig. 373, and Plate I, 1), two
filaments come to lie side by side, and the contents of some or all of the cells of one
thread round off, each cell-wall growing out into a short tube towards a cell of the
other thread. Each cell of the other thread then either swells up towards this tube
or puts out a similar tube, and the walls coming into contact are absorbed, an open
canal (conjugation-canal) thus being formed between the two cells. The con-
tents of the first cell then passes through the canal into the cavity of the second,
the contents of which has also rounded off, and fusion occurs between the two

gametes. The whole of the cells of two filaments frequently conjugate about the
Von. IL. as

658 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

same time, and the series of conjugation-canals thus formed give the appearance of
the rungs of a ladder. All the zygotes are formed in one filament, which we may
consider as physiologically female, its gametes being relatively passive compared
with those of the other (male), which initiate the process, and actively pass through
the canals, The relative behaviour of the two threads shows that an influence is
exerted by the male on the female cell, the former determining the outgrowth and
direction of the tube belonging to the latter, as well as the rounding off of the
female gamete. If the female tube is not put out opposite the male, the former
bends round to meet the latter, and if the male cell dies in the middle of the process,
the female tube goes on growing indefinitely, and the female gamete does not round
jtself off. The influence exerted is in all probability a chemical influence, a pheno-
menon which seems to occur in connection with the process of the conjugation of
gametes throughout the vegetable kingdom (cf. the remarks on pp. 68 and 413).

The chromatophore of the germinating zygote is formed from that of the female
gamete alone, the band belonging to the male gamete gradually disintegrating in
the zygote. This is an interesting example of the reduction of the specially vegeta-
tive portion of the male cell.

Zygnemacece—The cell of Zygnema differs from that of Spirogyra (Plate I, m)
in its remarkable and beautiful star-shaped chromatophores. There are two of
these in each cell, occupying positions equidistant from the centre of the cell. Each
possesses a rounded central portion, containing a single pyrenoid, from which thicker
or thinner processes radiate in all directions. The nucleus forms a bridge between
the two chromatophores.

Conjugation takes place much as in Spirogyra, the zygote being formed either
in the conjugation-canal or in one of the conjugating cells.

Mougeotiacew.— This family is characterized by the possession of single axile
plate-like chromatophores, and by the fact that part of the protoplasm of a con-
jugating cell does not enter into the formation of the zygote.

The chromatophore, which possesses a single row of pyrenoids, can alter its
position according to the strength of the light to which it is exposed. In moderate
light the plane of its surface is at right angles to the line of the incident rays, in
stronger light it places itself in the same plane as these rays, so that they only fall
upon its edge. In very strong light it contracts to form an irregular body in the
centre of the cell.

In conjugation the cells of two threads either put out tubes, and form spherical
zygotes in the conjugation-canals (Mesocarpus-type), or the two cells bend towards
one another, and form a four-sided zygote, one side of which occupies the centre of
each cell. The wall of the zygote thus cuts off the two ends of the two cell cavities,
so that the zygote appears as if it were surrounded by four empty cells (Stawro-
spermum-type). These, however, soon break off.

Gonatonema forms so-called aplanospores in the following way. A cell increases
to double its former length, its contents (chromatophore, &c.) dividing into two
parts. A swelling is formed in the middle of the cell, into which the two chromato-

THALLOPHYTA. 659

phores and the bulk of the protoplasm move from each end. A wall is now formed
round the contents of this swelling. Although the behaviour of the nucleus has
not been followed, this certainly suggests a reduced process of conjugation, each
half of the cell representing a gamete.

Mougeotiopsis is a genus whose chromatophore possesses no pyrenoids.

Alliance X.—Charales.

Family: Characee, the Stoneworts.

Are green submerged plants with segmented axes bearing whorls of leaf-like
appendages at the nodes, upon which the antheridia and oogonia are borne. The
antheridia are spherical and contain a large number of filaments, each cell of which
produces a spermatozoid with two long cilia. The oogonium consists of an egg-cell
inclosed in five spirally-twisted, tubular cells; on germination the egg-cell gives
rise to a simple segmented filament (the pro-embryo) from which the adult form
arises as a lateral bud. There are no swarm-spores. Vegetative propagation is by
bulbils, detached branches, &c. This alliance, though placed here in sequence with
the other alliances of Green Algz, is probably remote from them in actual affinity.
The Charales form an isolated and anomalous group, and various views are enter-
tained as to their true position.

Members of this group occur very commonly in ditches, ponds, &, and in
brackish water. In the Norfolk Broads very extensive growths of these plants
occur in the muddy bottom of the Broads, the living plants resting on the decom-
posing remnants of former generations; in this way the bottom level is being
gradually raised.

Chara fragilis (see fig. 874) is perhaps the commonest species of the group, and
is cosmopolitan in its distribution. The plant is some 12 inches high, dnd consists
of axis with whorled leaf-like appendages inserted at the nodes. The axis consists
of a number of long cells (the internodal cells) with which alternate the short
nodal cells. The former remain undivided, whilst the latter originate the append-
ages and also a number of tubes, which, growing both upwards and downwards,
everywhere cover in the internodal cells, forming a sort of cortex. The “leaves”
have a structure essentially similar to that of the stem; they are, however, of limited
growth (fig. 3743). They bear at their nodes tiny leaflets and the reproductive organs.
The oogonia and antheridia occur together in this species (figs. 374% and 374°),
the latter below the former. The antheridia are spherical orange-coloured bodies,
consisting of eight shields or plates whose edges dovetail into one another; each
bears a process (the manubrium) on its inner surface, and each of these manubria
bears a tuft of filaments (fig. 374°), in every cell of which a coiled spermatozoid is
produced bearing 2 long cilia at the tip (figs. 374° and 374”). The shields now dis-
articulate and the spermatozoids escape. The oogonia (or amphigonia) remotely
resemble the archegonia of Ferns (ef. fig. 3467, p. 472). Each contains a big oval egg-
cell inclosed in a sheath of 5 tubes spirally wound around it. The tips of these tubes

660 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

form a crown surmounting the oogonium (fig. 374°). At fertilization the spermato-
zoids penetrate between the cells of the crown, so reaching the egg-cell. The wlele
oogonium is soon detached and remains dormant through the winter. In the spring
it germinates, pushing out a tube which becomes transversely segmented. This :
the pro-embryo. From it, as a lateral bud, the adult sexual plant pulses. This
process resembles that of the Mosses, in which the leafy Moss-plant arises from

Fig. 374.--Structure and reproduction of Chara fragilis.

1 A portion of the plant. 2 A piece of the axis with appendages, upon which are inserted the sexual organs. $8 A single
appendage, showing the flask-shaped archegonia and spherical antheridia. 4 A single antheridium. 5 A plate of an
antheridium with manubrium and whip-like filaments of cells containing spermatozoids. & Several cells from one of the
whip-like filaments: the cells in the middle contain each a spermatozoid; the spermatozoid is escaping from the upper-
most cell; the lowest cell is already vacated. 7 A single spermatozoid. & Archegonium inclosing the egg-cell. 1 nat. size;
2x10; x15; 4x35; 5x100; §x300; 7x500; 8x50.

the protonema as a lateral bud. But the comparison with Mosses must not be
pushed too far, as in Chara there is no sporogonium. There are some 67 species of
Chara, of which C. foetida is also very common. Many of them are covered with
stiff hairs, and they are for the most part brittle owing to the incrustation of
carbonate of lime (¢f. vol. i. p. 260). The phenomenon of parthenogenesis in Chara
erinita has already been described in detail (pp. 463, 464).

In Chara stelligera (=Tolypellopsis ulvoides) the nodes of the stem become

THALLOPHYTA, 661

swelled out with starch, and assume a stellate form (starch-stars). They serve as
organs of vegetative propagation.

The other large genus of Characew is Nitella, It is especially distinguished by
the fact of its stems and leaves being destitute of cortex. There are 67 species of
Chara and 77 of Nitella.

Characeous fruits (Gyrogonites) are met with in large numbers in the lower
chalk and in tertiary formations. Only rarely are fragments of the stems, &.,
recognized.

Alliance XI.—Pheophycee.

Families: Ectocarpacew, Sphacilariacee, Cutleriacee, Laminariacee, Fucacee.

Includes the whole series of the Brown Sea-weeds, essentially characterized by
the fact that their chlorophyll-corpuscles include, in addition to chlorophyll, a brown
pigment, Phycophzein, which masks the green colour of the chlorophyll. The forms
included under this alliance are all multicellular, and range from simple threads of
cells to large complex forms showing a differentiation into a root-like attachment-
organ, stipe, and expanded leaf-like frond. In several of these larger forms the
internal structure almost rivals that of Flowering Plants in complexity. Within
the limits of the group we find sexual reproduction, in some cases by the fusion of
equivalent motile gametes (ef. p. 50), in others of well-marked egg-cells or sper-
matozoids. Fertilization and the complete life-history has been studied in relatively
few cases.

Ectocarpacee.—These are mostly filamentous and often branched. Attached to
the branches are the sporangia and gametangia. From the former motile zoospores
are liberated. From the latter similar bodies—the gametes—are liberated. These
possess two cilia, attached laterally to the gametes. The process of fertilization
has been followed in Ectocarpus siliculosus. Certain of the gametes come to rest
first, and these are approached by a number of other gametes, which swarm around
them. Ultimately one of the swarming gametes fuses with the resting gamete and
fertilizes it. This process has been thought to indicate the existence of a certain
sexual differentiation amongst the gametes, the gamete which comes to rest first
being the egg-cell. However, there is no demonstrable structural difference between
them.

Sphacelariacec.—The filaments consist of many layers of cells. Reproductive
organs agreeing in the main with the last-named family.

Cutlervacew.—Mostly branched, ribbon-like forms. The gametangia are arranged
in tufts, and the gametes differ in size, but both possess two cilia.

Laminariacee.—Perhaps the most interesting family of the alliance. Many
forms are known to liberate motile reproductive cells from various portions of their
surface, but the fate of these bodies has not been ascertained. They are large marine
forms, some of them attaining gigantic dimensions. Laminaria digitata, which
grows in quantities near low-water mark on our coasts (where it forms a regular
“Laminaria-zone”), has a tuft of powerful roots holding it to the rocks, a long

662 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

stipe, and a flat, expanded leaf, deeply lobed like a hand. It is often met with two
metres in length. The leaf is of a leathery consistency, and the flattened or cylin-
drical stalk has a wide parenchymatous cortex and central “medulla”, in which run
curious tubes (the “trumpet hyphe”) which swell out at intervals, the swelling
being traversed in a transverse direction by a delicate sieve-plate. The stem
possesses a peripheral cambium-like zone, which adds each year a new zone of tissue
to the cortex. The stems, which are sometimes found much thicker than one’s

Fig. 375.—Laminariacem, with perforated fronds. ‘ ,

1 Agarum Gmelini (after Riocreux), 2 Thallasiophyllum clathrum (after Postels and Ruprecht). Both much reduced.

thumb, show in section a series of rings, reminding one of the annual rings of a
dicotyledonous stem. A long ribbon-like form, L. saccharina, is also common on
our shores. In other forms the frond is branched and often curiously appendaged
at the base. In the two genera represented in the accompanying illustration (figs.
375? and 3757) Agarum (from the North Atlantic) has a simple, Thallasiophyllum
(North Pacific) a compound frond. In both the fronds are perforated or fenestrated.
Lessonia (Southern Pacific) attains to tree-like dimensions and is much branched;
it has a stem as thick as a man’s thigh. But the two most impressive genera are
Macrocystis and Nereocystis. The former, which occurs throughout the southern
oceans and on the western coast of N. America, consists of a long stalk, sometimes
attaining a length of 300 metres, but in thickness not exceeding a penholder. To

THALLOPHYTA, 663

this stalk are attached a series of long ribbon-like leaves, each of which, just at its
point of insertion upon the stem, swells into an air-bladder about the size of a
pigeon’s egg. Thus the stem, which is attached below, is buoyed up, and the long
leaves depend into the water. In structure the stem is not unlike that of a Lami-
naria; but it possesses in addition to the medulla, with its trumpet hyphe, a zone
containing large
sieve-tubes, which
resemble those con-
tained in the soft
bast of a Flower-
ing Plant (ef. vol. i.
fig. 104, p. 45, and
fig. 1257, p. 469).
Nereocystis, occur-
ring on the W.
coast of N. America,
consists of a long
stalk (attaining to
a length of nearly
100 metres), at-
tached at its lower
extremity and ex-
panding above into
a huge _ retort-
shaped air-sac,from
the surface of which
a number of fronds
(6-10 metres in
length) arise. Like
Macrocystis, its
stem contains well-
marked sieve-tubes.
It is used by the

Fig. 376.—Fucus vesiculosus.

1 Vertical section through a female conceptacle. 2A single oogonium from the conceptacle

Aleutians as fish- surrounded by sterile hairs, 8 A detached oogonium containing 8 egg-cells; the inner
: li O f L Jamella of the wall is much swollen. 4 Liberation of the egg-cells. 150; 2,8,4x160.
ing-line, a- (After Thuret.)

minariacese about
90 species have been distinguished (including 30 species of Laminaria).
Fucacee.—Includes a number of the larger common sea-weeds. They are
characterized—like the last family—by a segmentation into a well-marked shoot
and organ of attachment. The former is usually flattened and branched, and often
bears air-bladders. Reproduction is by means of spermatozoids and non-ciliated
egg-cells, which arise in flask-shaped hollows (conceptacles) on definite portions of
the shoot or frond. Asexual reproduction by detachment of fragments.

| Univers)

fi branes |

t

664 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

The Wrack-genus Fucus forms an exceedingly conspicuous feature of our sea-
shore flora. The shoot is flattened and ribbon-like, branching in one plane and
attached to stones, &., by a sucker-like disc. In many species there is a midrib, as
also air-bladders. The tips of many of the branches are studded with little rugosi-
ties—really indicating
the presence of pear-
shaped hollows, the con-
ceptacles. From the lin-
ing of these conceptacles
project the oogonia and
branched filaments bear-
ing antheridia respective-
ly. Asarule the male and
female organs occur on
distinct plants, though in
some species the anther-
idia and oogonia occur
side by side in the same
conceptacle. The struc-
ture of the sexual cells
and the act of fertiliza-
tion (which occurs out-
side the mouth of the
conceptacle) have been
fully described on pp. 51,
52; they are represented
in figs) 876 and 377.
Sixteen species of Fucus
are distinguished, and
they occur for the most
part in the seas of the
northern hemisphere.
Fucus vesiculosus and

Seer
goo.

Soares
= era :

ALEK

Co
bey

fins ;

f AVL

[Bierrie?|
eters |

1 Vertical section through a male conceptacle. 2A portion of one of the shrubby, F
branched hairs bearing antheridia. % Spermatozoids escaping from the anther- . serratus are the com-

ean Rr soe with spermatozoids attached. 1x50; 2x160; yonest. Several other
genera are represented

in Britain, Pelvetia, Ascophyllum, Cystoseira, Halidrys, and Himanthalia. The
last-named genus is altogether peculiar, and consists of a top-shaped body at-
tached by its pointed end, whilst from the upper surface of the “top” arise
several ribbon-like outgrowths which branch repeatedly and attain to a length
of several metres. It is upon these ribbons that the conceptacles are borne. Of
exotic forms a few may be mentioned. Durvillwa from the southern seas resembles

a thick, fleshy Laminaria in habit; from the summit of its thick stipe arise a

Fig. 377.—Fucus vesiculosus.

THALLOPHYTA. , 665

number of irregular fleshy lobes, which are produced into branching, whip-like
filaments. Its tissues possess a curious honey-combed structure. It is stated that
in Chili, &., D. utilis is used as an article of food. Sargasswm is distinguished by
its high differentiation. It has cylindrical stalks bearing leaf-like appendages, and
little stalked spherical air-bladders, and receptacles for the sexual organs. Some
150 species of this very varied genus are known, scattered over the warmer zones
of the world. Particular interest attaches to the Gulf-weed (Sargassum bacciferum,
fig. 378) which forms the chief component of the floating masses of Sargassum in
certain regions of the Atlantic.
The Sargasso Sea has received its
name from the enormous amounts
of this floating weed which are met
with there. It occupies an area in
the Atlantic perhaps equal to that
of the continent of Europe. There
are two main accumulations, the
larger south-west of the Azores, the
smaller situated between the Ber-
mudas and Bahamas, whilst connect-
ing them is a narrow belt. The exact
nature of these accumulations is not
ascertained. According to one view
the Gulf-weed actually lives a pelagic
life, growing and multiplying in this
huge eddy in mid-ocean, and is
thoroughly adapted to its special
environment; whilst, on the con-
tending hypothesis, the vegetation of :

the Sargasso Sea is purely ephem- sia saa le sid iia
eral, does not reproduce, and is con-

stantly renewed by ocean currents, which bring with them countless fragments
forcibly torn by tempests from the shores of Florida and the Bahamas. It is further
alleged that the floating Gulf-weed is met with only in a condition more or less
unhealthy (moribund) and in various states of decomposition.

The weak point in the latter hypothesis is the lack of convincing evidence to
show that S. bacciferwm grows attached in the region of the West Indies, &., in
quantity sufficient to supply the Sargasso Sea. Of another species, S. vulgare,
there is plenty, but this is not the prominent constituent of the Sargasso Sea—
indeed a trained algologist, in passing recently through this sea, examined samples
amounting to more than a ton, but it was only S. bacciferwm he found. Here,
evidently, is still matter for the leisured naturalist.

Over 300 species of Fucacez (including 150 Sargassums) have been distinguished.

666 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Alliance XII.—Dictyotales.
Family: Dictyotacec.

A small group of Brown Sea-weeds distinguished by the fact that both egg-cells
and spermatozoids are destitute of cilia. The sexual cells are contained in club-
shaped vesicles, inserted in tufts on the surface of the plants. Asexual reproductive
cells (“tetraspores”) are formed in sporangia in fours. They include the common
Dictyota dichotoma and the beautiful iridescent fan-like Padina pavonia.

Alliance XIII.—Floridee, Red Sea-weeds.

Aquatic, for the most part marine, plants, which contain in addition to chlorophyll
a red or purple pigment, phyco-erythrin; the pigment, as in the brown sea-weeds,
is confined to definite corpuscles. Reproduction is by means of asexual spores
(tetraspores), and sexually by non-ciliated spermatia and procarps.

With the exception of Batrachospermum, Lemanea, and one or two other
genera, the Floridex are marine organisms and inhabit on the whole a deeper zone
than any other sea-weeds. Several views prevail as to the significance of the red
pigment. As has been already indicated (vol. i. p. 390) the rays of light, useful in
ordinary chlorophyll-assimilation, are soon absorbed, as white light traverses con-
siderable strata of water. Such light as penetrates some distance from the surface
is preponderatingly blue, and, as is now known, such rays are actually destructive
of vegetable protoplasm. It may well be then that the red pigment serves to screen
the protoplasm from the action of these rays, permitting the chlorophyll to make
use of such of the red rays as filter to it; or—what is more probable—the red
pigment is itself an assimilating pigment, either directly absorbing the blue rays
and allowing the protoplasm of the chlorophyll-corpuscles to use their energy for
building up complex food-materials, or indirectly (as indicated at vol. i. p. 390) by
altering their wave-length they are made serviceable to the chlorophyll-corpuscles.

The Floridez exhibit an enormous variety of form, and-almost all of them are
attached. There are the delicate cell-filaments of the Callithamnions, the corticated
Polysiphonias and Ceramiums so common on our coasts, the fleshy cylindrical
Gracilarias and Polyides, the flat and lobed Chondrus and Gigartina, the leathery
Iridea, and a host of others. One of the most beautiful of British genera is
Delesseria, with its creeping stalk and crimson leaves with midribs and veins. In
some species the leaves are entire, in others their margins are sinuous and lobed.
Of all red sea-weeds perhaps the Australian Clawdea holds the palm for beauty with
its large latticed, rose-pink fronds. Certain groups, Corallina, Melobesia, Litho-
thamnion, &c., are encrusted with large amounts of carbonate of lime, and build
regular banks and reefs under the sea. In all there are some 280 genera and 1800
species of Floride.

Reproduction by means of asexual spores is a common phenomenon in the group.
These spores, though not invariably, are most frequently formed in clusters of four,

THALLOPHYTA, 667

and are termed tetraspores. In the simpler forms they arise in little projecting
sporangia, in other cases they are on specialized branches or embedded in the sub-
stance of the frond.

The sexual organs, however, are very remarkable, and differ from those of other
Thallophytes. The male cells arise from clusters of' cells (antheridia) at the tips of
branches or in groups upon the surface of the frond. Each antheridium liberates
a single, non-ciliated male cell termed a spermatium. The female organs or pro-
carps consist of a filamentous receptive organ, the trichogyne, and a basal part,
the carpogonium (ef. figs. 2047 and 204°, p. 53). Besides the carpogonium there are
auailiary cells, to be described directly. The process of fertilization has been
followed in detail in Nemalion since the earlier portions of this volume passed
through the press, and we now know that the suggestion of an osmotic fertilization
in the Floridee (ef. p. 60) is erroneous. The spermatium becomes attached to the
trichogyne, and at this point the wall of the trichogyne is absorbed. The nucleus
of the spermatium enters the trichogyne and travels down it to the carpogonium at
the base, where it fuses with the carpogonial nucleus. The carpogonium now divides,
giving rise to a mass of spores (the carpospores). In other cases the process is less
simple. As before there is a trichogyne and carpogonial cell, but associated with
the latter a number of auxiliary cells. The carpogonium when it is fertilized does
not give rise at once to a mass of spores, but enters into a process of conjugation
with these auxiliary cells, and from them the carpospores arise. This conjugation
may be an immediate fusion, or may be brought about by the instrumentality of
special tubes. Thus we may suppose the fertilizing influence to be transmitted.
In some cases (as in Dudresnaya) this may take place over considerable distances,
from branch to branch. In the simpler forms the procarps are modified branches
projecting freely into the water; in the more fleshy and ribbon-like forms they are
sunk in hollows on the thallus and often associated with a large number of auxiliary
cells. The trichogyne projects into the water through a small pore in the portion
of the surface which roofs over the procarp and auxiliary cells. As a result of
fertilization of the carpogonium and its conjugation with the auxiliary cells, a large
mass of carpospores arises, which raises up the surface like a blister.

Fossil remains of red sea-weeds occur under the name of Nullipores. These are
the calcareous incrustations of the Corallinas, Melobesias, Lithothamnions, &c., men-
tioned above. They occur in both the secondary and tertiary rocks. The Leitha
limestone, largely used for building purposes in Vienna, comes from extensive nulli-
pore banks in the Leitha Mountains, south-west of Vienna on the Hungarian
frontier, and, just as in Paris many of the finest buildings are constructed of the
* eonsolidated calcareous remains of Foraminiferz, so in Vienna are the incrustations

of certain red sea-weeds put to this purpose.

668 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Class V.—FUNGI.

Parasitic or saprophytic plants destitute of chlorophyll and for the most part
possessing a mycelium. Sexual reproduction known and generally admitted in
the Phycomycetes only. Asexual reproduction by means of spores and conidia.

Sub-class I.—PHYCOMYCETEs,

Mycelium for most part unicellular, tubular, and branched. Sexual reproduction
both by conjugation of equivalent cells and by egg-cells. LGo

Fig. 379.—Chytridiacez and Ancylistacee.

1,2,3 Lagenidium Rabenhorstii, parasitic upon Spirogyra. 4,5 Polyphagus Eugl 6 Rhizidi pophysatus, parasitic
on an oogonium of Saprolegnia.

Alliance XIV.—Oomycetes

Families: Peronosporece, Saprolegniaceee, Chytridiacee, Ancylistacee,
Entomophthorec.

Mycelium often very slightly developed; asexual reproduction by means of
swarm-spores; sexual reproduction by egg-cells. On the whole in this group we are
dealing with Fungi which very nearly resemble the Alge of the Alliance Siphonex
(e.g. Vawcheria) both as regards the structure of their mycelium and mode of repro-
duction. A loss of sexuality is to be noted in many members of this group.

THALLOPHYTA. 669

Peronosporec.—Are mostly parasitic upon Flowering Plants, and the cause of
many destructive diseases. They establish themselves by means of a branching,
tubular, non-septate mycelium which penetrates the intercellular system of the host-
plant (cf. p. 56). They propagate asexually by means of unicellular sporangia borne
on branched hyph which project from the stomates, &., of the host (cf. fig. 3817);
these sporangia (or spores as they are sometimes termed) liberate on a moist sub-
stratum a number of swarm-spores (figs. 3814%5°) which originate new plants.

Fig. 380.—Swarm-spores in Saprolegniacez and Chytridiacez.

1 Achlya prolifera. 2,8, 4 Successive stages of swarm-spore-formation in Achlya prolifera. 5 Chytridium Olla, parasitic on the
oogonium of the Alga Gidogonium; development of swarm-spores. 6 Saprolegnia lactea. 7 Development of swarm-spores
inthe same. (Partly after De Bary and Pringsheim.) 1x20; 2,8,4x400; 5x300; 6x100; 7x300.

Sexual reproduction also takes place by the formation of oogonia and tube-like
antheridia. The latter become attached to the former (fig. 381%), and, putting out
fertilizing tubes which penetrate to the egg-cell within the oogonium, transmit their
spermatoplasm. No spermatozoids are differentiated, but the spermatoplasm travels
en masse. The fertilized egg-cell enters on a resting stage, and when it germinates
may either give rise to swarm-spores (e.g. Cystopus) or grow at once into a new
plant (Pythiwm, Peronospora). To Phytophthora infestans is due the well-
known Potato-disease. The Fungus attacks the foliage and reproduces abun-
dantly asexually. Later, its mycelium penetrates to the tubers and passes into
a dormant state there. Consequently when stored these potatoes go bad, and if

670 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

used for planting are liable to reproduce the disease next year. Sexual reproduc-
tion is as yet not certainly known to occur in the life-history of the Potato-disease
Fungus. Phytophthora omnivora and Pythiwm de Baryanum attack and destroy
many young seedlings, causing them to “ damp off”. Various species of Peronospora
are known which attack large numbers of cultivated plants. P. parasitica works
havoe amongst the Crucifere; P. viticola (=Plasmopara viticola, fig. 381) has
been referred to as a deadly disease on the Vine; P. Vaciw on various leguminous

Fig. 381.—The False Vine-mildew, Peronospora viticola.

1A bunch of grapes attacked by the False Vine-mildew. 2 Spores or conidia on branched hyphe projecting from a stoma of
a Vine-leaf. 8 Fertilization, 4 A single conidium. & Swarm-spores arising within the conidium. 6 A single swarm-spore.
1 nat. size; 2x80; *5x350; ©x380. (86 after De Bary.)
crops; P. Hyoscyami on Tobacco-plants, besides which there are many others. The
effects of Cystopus candidus have already been mentioned (p. 525); it is common
upon cruciferous plants.
About 100 species of Peronosporee have been distinguished.
Saprolegniacee.—Are all aquatic and for the most part saprophytic; a few are
parasitic on fish. In structure they much resemble Peronosporesw. Swarm-spores
are liberated in large numbers from the enlarged ends of the hyphe (fig. 380).
see ae arise much as in Peronosporesx, but although the antheridia develop
ertilizi i i i i
ng tubes in several instances, no case has been observed in which an actual
transfer of spermatoplasm occurs. As a rule several or many egg-cells are produced

THALLOPHYTA. 671

in the oogonia (fig. 382), and these germinate parthenogenetically. Although the
sexual organs are still preserved in this group their function has been lost, leading
the way to their complete atrophy in many other groups of Fungi. Many members
of the group occur upon the bodies of dead insects and fish (e.g. various species of
Saprolegnia, Achlya, Aphanomyces). Aphanomyces phycophilus is parasitic upon
Alge (eg. Spirogyra) and Saprolegnia
Ferax upon Salmon, &c.

About 45 species have been distinguished.

Chytridiacee.—Small parasitic aquatic
Fungi whose mycelium is almost entirely
wanting; they produce characteristic spor-
angia which liberate uniciliate swarm-spores.
Polyphagus Euglenc develops a very delicate
mycelium, of which the branches become
attached to Euglena-cells (fig. 379°, two
Euglenas are thus attacked), and from the
central portion of the mycelium arises a
sporangium from which uniciliate swarm-
spores (fig. 379+) are liberated. These in
turn germinate, develop threads, and entangle
fresh Euglenas. Rhizidiomyces attacks the
oogonia of Saprolegnias, sending a branching
mycelium into their interior (fig. 379°) and
producing a pear-shaped sporangium at the
surface which liberates numerous swarm-
spores. Chytridiwm Olla (fig. 380°) pro-
duces its sporangia on the oogonia of Cdo-
goniwm; its swarm-spores escape by the

removal of a lid.
Over 180 species are known.

Fig. 382.—Achlya lignicola.

1 Oogonia with antheridia and fertilizing tubes; no fer-

Ancylistacew.—Very nearly resemble the tilization happens, however. 2An oogonium con-
se ie 5 si * * taining egg-cells which have put on cell-walls with-
Chytridiaceze in mode of life, but differ in out being fertilized. 1and2x400. (After Sachs.)

exhibiting sexuality. Lagenidiwm Raben-
horstii attacks cells of Spirogyra, &c. The spores become attached to the Spiro-
gyra-cells, and penetrate the wall (fig. 379") by means of a tube which branches
about within, forming a lobed, irregular body (fig. 379), which may open at the
outside, liberating swarm-spores (fig. 379*), or sexual organs may arise inside and
fertilization take place.

14 species have been distinguished.

Entomophthoree.—A group of forms almost all of them parasitic on insects.
They are adapted to non-aquatic life, and connect the Peronosporeew with the

Zygomycetes.
The tubes of these parasites having effected an entrance into the body of an

672 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

insect, bud and sprout there with great activity. Entomophthora radicans commonly
attacks caterpillars of the Cabbage-white (Pieris Brassicw). Having spread through
its interior, it sends out tufts of hyphz on the ventral side (fig. 383°), thus rooting
the caterpillar to the substratum. It now develops hyphe all over the body
wrapping up the caterpillar like a mummy (fig. 383 2), At the tips of these hyphe
conidia are abstricted and shot off to some little distance (figs. 383%*°). A con-

Fig. 388.—Entomophthoreex: Entomophthora and Empusa.

1 A caterpillar of the Cabbage-white Butterfly attacked by Entomophthora radicans. 2 The same caterpillar fully invested by
the Fungus. 3 Tufts of conidia-bearing hyphe from the back of the caterpillar. 4Conidia separating from the tips of the
hyphee. 5 Disarticulated conidia, 6 A Fly attacked by Empusa Musce. 7 Hyphe of Empusa Musce, from the tips of
which conidia are being shot off. §® Conidium inclosed in sticky mucilage. 1,2,6 nat. size; 3x80; 4 7800; §x 630
(After Brefeld.) , one : ,

Jugation of branches sometimes occurs, whilst in other cases fruits are formed
parthenogenetically. Hmpusa Musce produces a disease common amongst flies in
the autumn. The Fungus having effected an entrance into the body of a fly
gradually fills it up with its sprouts. In due time tubes penetrate the surface and
develop conidia at their extremities (fig. 3837). These are shot off as in the last
case, and one may often see flies stuck to the window-pane in autumn surrounded
by a halo of these conidia (fig. 383 °),
About 80 species of Entomophthorex are known.

THALLOPHYTA, 673

Alliance XV.—Zygomycetes.
Families: Mucoracew, Mortierellec.

Are mould-like saprophytes with a much-branched, non-septate mycelium;
sexual reproduction by conjugation; Swarm-spores never met with. The com-
mon Mucor Mucedo (fig. 384) may be regarded as typical of this group. Its
mycelium establishes itself on the substratum, and develops long-stalked sporangia
at various points on its sur-
face (fig. 3841). In each
sporangium (fig. 384%) numer-
ous spores are contained, and
these can germinate, producing
new mycelia on a_ suitable
substratum. A conjugation of
branches of the mycelium
leading to the production of a
fruit or zygospore (fig. 384°)
occasionally takes place, but
the sexual method of repro-
duction is much commoner in
other members of the group
(ef. pp. 58, 54). The zygospore
(or zygote) is invested in a
strongly thickened membrane
and can remain dormant for
a considerable period. The

hyphe in many of the Mucors |
can break up into continuous
chains of cells which disarticu-
late and propagate the plant;

1 Mycelium with stalked sporangia; x40. 2A single sporangium; x 260.
these offshoots are known as 3 A zygospore produced by conjugation; x160.

chlamydospores or gemme.
It often happens amongst the Mucors that although the conjugating branches are

produced, they do not conjugate but each produces a fruit parthenogenetically.
These, in contradistinction to zygospores, are called “azygospores”. Or, as in
Mucor tenwis, the “conjugating branches” no longer arise in pairs but isolated;
these also form azygospores. Thus in this group, as in the Saprolegniacee of the
alliance Oomycetes, we note a tendency for sexuality to become obsolete (cf. p. 670).
A good deal of variety exists in the Mucoracex in the arrangement of the sporangia.
In Thamnidiwm the sporangial branch ends in a large sporangium, and in addition
bears laterally a number of tiny sporangia (sporangioles) containing four spores each,

whilst in Chetocladiwm there is a further reduction, and the sporangioles contain
Vou. IL 93

Fig. 384.—Mucor.

674 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

but a single spore. Whilst the bulk of Mucoracex are saprophytes on animal ex-
creta, &c., a certain number are parasitic on Mucor itself as well as other Fungi.

The Mortierellew, though in general resembling Mucoracee, are distinguished by
the fact that their zygospores become invested in a plexus of mycelial hyphe which
form a sort of pericarp around the fruit. The base of the sporangial hypha also is
invested in a sort of bird’s-nest. This condition is of interest as it leads on to the
more complex fruits of higher Fungi.

The Zygomycetes include 125 species.

Sub-Class II].—Mzsomycetss,

Mycelium multicellular; asexual reproduction alone is known by means of
spores (not limited in number) developed in sporangia; or by conidia. They are
regarded as occupying an intermediate position between the lower Fungi and the
two large groups of higher Fungi, the Ascomycetes and Basidiomycetes respectively.

Alliance XVI.—Hemiasci.

Tube-like sporangia containing an unlimited number of spores. This alliance
leads on to the Ascomycetes.

Families: Ascoidec, Protomycetes, Thelebolew.

These are mostly simple forms of parasites characterized by the indefinite
number of spores contained in their sporangia. Some of them produce chlamydo-
spores freely. Thelebolus is interesting in that its sporangium is inclosed in a
cortex and may be compared with Mortierella of the Zygomycetes on the one hand,
and with the corticated Ascomycetes (carpo-asci) on the other.

There are about 20 species belonging to this alliance.

Alliance X VII.—Hemibasidii.

Parasites with a septate mycelium, which forms numerous chlamydospores.
From these spores a promycelium is developed on which conidia (sporidia) are

produced. No sporangia are formed. This alliance is thought to lead on to the
Basidiomycetes.

Families: Ustilaginacee, Tilletiacee.

These are all parasitic forms, and are known as the Smuts. The mycelium grows
in the living tissues of the host, and concludes its development with the production
of chains of chlamydospores (cf. p. 673), which are provided with a thick
membrane, and are usually dark in colour. It is in respect of this cheracter that the
name “Smut” has been given. Very often these chlamydospores are produced in
connection with the fruiting organs of the host-plant (various Grasses, &e.). The

THALLOPHYTA, 675

chlamydospores only germinate after they have been distributed, and in a very
characteristic manner. A short tube is formed, and from this (the promycelium or
basidiwm, ef. p. 674) conidia (=sporidia) are abstricted. In the Ustilaginacex this
basidium is septate and the conidia are abstricted laterally; in the Tilletiaceze the
basidium is non-septate, and the conidia are abstricted as a crown at the apex. This
is the main difference between the two families, The conidia, which are budded
off from the promycelium, have the power of budding in a suitable soil with enor-
mous facility, forming new conidia, and this may be continued for a considerable
time. In this way the soil becomes thoroughly infected, and should a young seed-
ling host-plant arise, it is almost certain to be penetrated and invaded by one of
these germ-like conidia.

Ustilaginacee.—These are the Smut-fungi properly speaking. Ustilago segetwm
(= Ustilago carbo), the common Smut of Wheat, Barley, Oats, &., has been very
fully investigated. The cereals in question become infected when quite young by
the tiny conidia, which put out delicate germinal tubes and penetrate the young
growing tissues. Should the young plants escape infection at this stage, they are
safe against the parasite, which cannot penetrate the hard, adult tissues. The tubules
of the Ustilago penetrate from cell to cell, and take up their position at the growing
point. Here they keep pace with the growth of the host, but the presence of the
parasite is not manifest externally until the grain begins to ripen. As the grains
begin to swell, the fungus increases rapidly, and occupies the greater portion of their
substance with its mycelium. It thrives, of course, at the expense of the food which
would otherwise have served in forming the embryo and reserve of food-material in
the seed. Finally, the Fungus resolves itself into masses of black chlamydospores—
the “smut”—which appear between the glumes of the ear. These chlamydospores,
as already stated, after a period of rest, produce their promycelia and bud off
conidia, which in turn bud off other conidia, and so the ground is kept infected. It
was formerly a matter of mystery how the Fungus got into the host-plant, as traces
of it were not recognized till it burst out in the ripening ear in the “smut” stage.
It is only comparatively recently that the period of infection has been recognized,
and the fact that the mycelium grew up, so to speak, with the host-plants was fully
realized. Ustilago Maydis produces hypertrophied growths on the Maize, and has
been alluded to in a former chapter (cf. p. 524). Ustilago violacea attacks the
stamens of many Caryophyllacex, developing its chlamydospores in place of pollen
in the anthers. Ustilago longissima is very common in the leaves of the aquatic
Grasses Glyceria aquatica and G. fluitans; it produces its chlamydospores as long,
parallel, black lines.

More than 60 Ustilagos have been distinguished ; a large number of them attack
cereals and other grasses.

Tilletvacee.—Have on the whole a life-history resembling the Ustilaginez ; their
main point of difference residing in the fact that the promycelium is unsegmented,
and produces its conidia in a crown at the apex. Tilletia Tritice attacks wheat. In
Urocystis the spores are clustered into little balls, the accessory spores forming a

676 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

sort of cortex around the central spore which germinates as in Tilletia. Urocystis
Viole is common on the leaf-stalks and blades of Violets.
About 100 species of Tilletiaceze have been distinguished. .

Sub-class III.—Mycomyrceres.

Mycelium many-celled. Reproduction asexual, either by spores of limited num-
ber in asci, or by conidia of limited number on basidia.

Alliance X VITI.—Ascomycetes.

Parasitic (or saprophytic) Fungi, producing spores in special] tubular sporangia,
the asci. These spores, termed ascospores, do not exceed 8 in number. In addition
to the asci there are subordinate conidial fructifications.

Families: Exoascacee, Perisporiacee, Pyrenomycetes, Discomycetes.

As stated, this alliance is characterized by the possession of sporangial fructifi-
cations, consisting of tubular asci containing as a rule 8 ascospores. A number of
such asci are shown in fig. 388° with sterile supporting hyphe, the paraphyses,
between them. In addition to these ordinary and typical ascus-bearing fructifi-
cations, secondary fructifications producing conidia or chlamydospores are largely
met with; consequently many of these Fungi appear under several forms in addition
to the ascus stage. The Ascomycetes are divided into families according to the
‘characters of the ascus-fruit. In the Emoascacewe the asci are borne freely and
exposed on the mycelium; in the other three families in special receptacles. In the
Perisporiacece the group of asci is contained in a nut-like or tuber-like body; in
the Pyrenomycetes the asci are produced in special pear-shaped excavations in a
solid tissue which open by a pore to the exterior; in the Discomycetes the receptacle
forms an open plate or cup, or sometimes an irregular body covered with the layer
of asci.

Exoascacece.—This family comprises the parasitic genera Exoascus and Taph-
rina, the gall-like deformations caused by which were so fully described on pp. 524
and 527. The tissues of the host-plants are penetrated by the mycelia of these
forms, and the asci are produced over the surface of the parts attacked, generally
bursting through the cuticle of the epidermis. Each ascus contains 8 spores, but in
many species many more than this number are often found; this is due to the fact
that the 8 original ascospores begin to bud whilst still within the ascus, producing
a large number of secondary spores (conidia). Ewoascus has a perennial mycelium,
and to its species are due a large number of the “witches’-brooms” and other
hypertrophies. &. Prwni produces the “ pocket-plum” (ef. p. 524); E. Alni-incanee
the curiously altered Alder catkins represented in fig. 3581 (p. 523); E. Carpini the
birds’-nest-like witches’-brooms of the Hornbeam; FE. deformans the “curl” of
Peach-leaves. Taphrina is largely a leaf-parasite, and its mycelium is not peren-
nial. T. carnew causes blisters on the leaves of the Birch.

THALLOPHYTA, 677

About 50 species of Exoascacew have been distinguished.

Perisporiacece——Here are included all forms in which the asci are inclosed in
fruit-like bodies, 4.¢. the Mildews, Moulds, and Truffles.

The Mildews are chiefly leaf-parasites, and spread their mycelium over the
surface of the foliage and send their suckers (or haustoria) into the epidermal cells
(cf. fig. 82%, vol. i. p. 165). In due time they produce their ripe ascus-fruits like
tiny black grains scattered over the surface of the leaf. Each of these fruits con-
sists of a shell-like investment inclosing one or more asci, each of which contains
8 spores. Sphcerotheca is the simplest form, there being but a single ascus in its
fruit. S. pannosa is the Rose-mildew, and S. Castagnei the Hop-mildew, a very
destructive parasite in Hop-growing districts. Erysiphe has several asci in its
fruits, and includes the well-known EH. Tuckeri, the true Mildew of the Vine (to
be distinguished from Peronospora viticola, figured on p. 670, which is the false
Mildew). A tropical genus of leaf-parasites allied to our Mildews is Meliola, which
is widely distributed.

The Moulds include several exceedingly common saprophytes which make their
appearance on the most various sorts of organic matter. The Blue Moulds, which
occur on jam, bread, leather, &., are probably the best known and most commonly
recognized of all the smaller Fungi. These forms spread their mycelia over any
suitable substratum, and penetrate it with their hyphe. Their usual fructification
is not the ascus-fruit, but clusters of conidia, borne on erect hyphe, which stand out
from the mycelium. Two common Moulds are represented in fig. 193, p.18. Asper-
gillus niger (figs. 193* and 193°) bears its conidia in spherical tufts on enlarged
aérial hyphe. The swollen end of an aérial hypha is densely set with cylindrical
cells, from which the conidia are abstricted one after another. Penicillium crusta-
ceum (figs. 193° and 193°) is very similar, but here the conidia are borne on a
hypha which branches near its extremity like a compound umbel. Another form,
Eurotium, is shown in fig. 3857, p. 679. The ascus-fruits of these Moulds are not
very conspicuous, nor are they always very plentifully developed. They arise on
the mycelium after the conidial stage is over, and when ripe are about the size of
small shot. They commence by the entwining of certain hyphal branches (Pent-
cillium, fig. 193%, p. 18; Hurotium, fig. 385°, p. 679) which have been regarded as
representing male and female organs (cf. p. 60). That fertilization takes place is
strenuously denied by many modern mycologists, and the sexual nature of the
entwining hyphe is not universally recognized. Be this as it may, the result of
the process in question (which also takes place in the Mildews) is the formation
of a sinuous hypha, which becomes embedded in a dense cortical sheath which
grows up from the mycelium close by the place of origin of the entwined hyphe.
This is the young fruit-body; that of Hurotiwm is shown in section in fig. 385 7°.
From the central hypha numerous asci, each containing 8 spores, are ultimately
developed (figs. 1937 and 385"), The ripe ascus-fruit, which frequently takes
several months to mature, consists of a hard outer shell containing numerous asci
(one of these fruits is shown in fig. 385’, in the right-hand bottom corner); it is

678 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

able to remain dormant over long periods. Aspergillus is sometimes parasitic,
and is stated to promote a diseased condition of animal tissues known as mycosis.
A. fumigatus is found growing spontaneously in the air-passages of birds and in
the human lungs.

Tuberacee.—These are subterranean saprophytes whose mycelia grow in humus.
Their fructifications are solid, tuber-like bodies of various sizes. The Truffles
(Tuber rufum, T. melanosporum, T. estivwm, &e.) are well-known, and several of
the species are esteemed as delicacies. In section the Truffle-fruit shows a curious
mottled appearance due to its irregular chambered character. The chambers are
filled with hyphe which produce numerous oval asci, each containing 4 spores
(of. fig. 3871, which represents an enlarged chamber); the spores are covered with
delicate spines. The wall of the fructification consists of a hard parenchyma-like
layer, and possesses a rough and warted exterior. As the fructification ripens the
mycelium disappears, the Truffles being found detached in the soil. The spores are
ultimately liberated by the decay of the fruit. Hlaphomyces produces fruits about
the size of a nut. The mycelium of species of this genus is concerned in the for-
mation of the fungal investment or mantle of the roots of Pine-trees known as
mycorhiza (cf. vol. i. pp. 249, 250); in the Amentaces, &c., neither the species nor
group to which the Fungi forming this mantle belong has been ascertained.

Pyrenomycetes—An extremely large and varied group, including both parasitic
and saprophytic forms. The essential character of the family is the presence of
flask-shaped chambers with a pore at the apex in which the asci are produced.
The chambers, the perithecia, may be either solitary upon the mycelium in the
simpler forms or embedded in receptacles of most varied form (the stromata) in the
more complex. Sections of perithecia are shown in figs. 385° and 386°. A great
many Pyrenomycetes possess conidial as well as ascus-fructifications. The conidia
may arise in tufts from the surface of the mycelium or in urn-shaped cavities—not
unlike perithecia—which have been termed pycnidia. As a rule, the conidial pre-
cedes the ascal stage. This variety in fruiting has led to the recognition of several
forms, which are only stages in the life-history of one Fungus. Consequently, as
knowledge extends, many of these supposed species have to be suppressed.

Among the simpler forms may be mentioned Podospora, which produces solitary
sessile perithecia upon its mycelium. Polystigma rubrum, which occurs on the
leaves of species of Cherry and Plum, produces a brilliant red spotting on the leaves.
The mycelium permeates the internal tissues, and during the summer the conidial
receptacles or pycnidia are formed. Later, usually in the following spring, in the
fallen leaves, the perithecia arise, and the ascospores now liberated infect the young
foliage in the vicinity. Nectria cinnabarina, another fairly simple form, occurs as
little red cushions on the branches of Horse-Chestnut, Elm, Sycamore, &.; these
cushions burst through the bark budding off conidia (this is the bright red stage),
whilst later, as tiny lobes, the perithecia arise upon them, each lobe containing a

single perithecium (this is the dull crimson stage). The number of simple parasitic
Pyrenomycetes is almost endless.

THALLOPHYTA, 679

Fig. 385. —Ascomycetes.

1 Cordyceps Taylori, a pyrenomycetous Furgu which attacks caterpillars; the branched antler-like stroma has developed
‘from the sclerotium, and its lower warted portion bears the perithecia. 2 Three perithecia; enlarged. % A perithecium
in section. +4 Two asci containing filamentous spores. * Vertical section of a perithecium of Xylaria Hypoxylon.
6 Ascus of same. 7 Mycelium of Eurotium bearing a conidial hypha (to right, above), a commencing fruit (to left), and
a ripe ascus-fruit (to right, below). 8 A conidium of the same being abstricted. 9% Entangled hyphe from which a fruit
arises; the spiral central hypha has been interpreted as a female organ, the tubes growing up the side as male. 190A
young fruit of the same in section; the asci arise Jater from the large coiled central hypha. 11 A single ascus of Eurotium.
Inat. size; 2,8,5x 50-90. 4,6x500; 7x190: 8-11 250.

680 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Of complex forms with stromata we may mention Cordyceps, Xylaria, and
Claviceps. Cordyceps militaris and other species attack caterpillars. The germ-
tube having once effected an entrance into the body of the caterpillar and estab-
lished itself in the superficial layers begins to sprout vigorously, these sprouts being
carried in the blood to all parts of the body. The sprouts now grow into hyphae,
and gradually the whole caterpillar is replaced by a dense fungal tissue which

1

Fig. 386.—The Ergot of Rye, Claviceps purpurea.

1 Ear of Rye showing two sclerotia of the Fun
8 Stalked stromata arising from the sclerot
thecia at the edge. 5 Vertical section thro:
spores. § Filamentous spores. 1,8 nat, s

gus. 2 Conidia arising from the mycelium which develops around the ovary.
ium. 4 Longitudinal section through the head of a stroma showing the peri-
‘ ugh two perithecia showing the asci. 6 Asci. 7 Ascus liberating its filamentous
ize; 2x 200; 4x40; 5x50; 6 and 7x 700; 8x 760. (Partly after Tulasne.)

maintains outwardly the form and appearance of the caterpillar, although of animal
substance but little traces are left. This fungal mass is known as a sclerotiwm, and
it can remain dormant for some time. Ultimately a branching stroma arises from
the sclerotium (Cordyceps Taylori, fig. 3851, p. 679), or, in C. militaris, several club-
shaped stromata. These remarkable stromata are covered with little papill on
their lower portion, and each of these papille corresponds to a perithecium
(figs. 385? and 385%). The spores in the asci are long and slender (cf. fig. 8854). A

iy

THALLOPHYTA. 681

Pyrenomycete which produces an antler-like stroma resembling that of Cordyceps
Taylori, and which is exceedingly common on old tree stumps, is Xylaria
Hypoxylon. Indeed, the stroma represented in fig. 3851 would almost do for that
of this Xylaria. It is purplish in colour below where the perithecia are borne; at
the tips it passes over into a glaucous grey colour, this bloom being due to the
conidia, which are abstricted in this region. Another curious fingered species, X.
polymorpha, is also met with in similar situations. Claviceps purpurea, the Ergot

1 6 4

5 &

Fig. 387.—Various Ascomycetes.

1 Section through part of a Truffle (Tuber melanosporum) showing a portion of the cortex (below) and a chamber containing
oval asci, each of which contains 4 spores, 2 Vertical section of the apothecium of a discomycetous Lichen, Physcia
siliaris (after Sachs). 8 The Yeast-plant, Saccharomyces cerevisew. 4,5,6 Single Yeast-cells showing development of a
sprout. 7 A cell containing two spores. 1x200; 2x60; 3x600; #7x1000. (Partly after Rees.)

of Rye and other grasses, is a very interesting form. The spores attack the ovaries
of Grasses and invest them with a mycelium from which conidia are abstricted in
large numbers (fig. 8867). These can at once infect new plants. Gradually the
whole ovary is replaced by a mass of fungal substance, the sclerotium. In the
autumn at the time of harvest the ears of Rye may be seen with these dark
sclerotia projecting from them (fig. 3861). Care has to be exercised that they do
not get mixed up with the grain, as the Ergot contains an alkaloid and other
poisonous substances, and if intermingled with food causes a disease which has
received the name of ergotism. The sclerotia remain dormant through the winter,

682 . THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

but in the spring give rise to their stromata, which consist of a number of orange-
coloured spherical bodies borne on purple stalks. A germinated sclerotium is shown
in fig. 386°, The head bears the perithecia at its periphery (figs. 3864 and 386°),
and in these are contained the asci with their filamentous spores (figs. 386 ® ” 8).

In addition to the forms enumerated above, a large number of pyrenomycetous
Fungi are found always associated with Alge into symbiotic communities known as
Lichens (cf. vol. i. p. 244). Though in a strict systematic review these forms should
be noted here, still, as Fungi from at least two other groups occur in similar
relations to Algz, it will be convenient to treat them all under one heading, rather
than scattered over the alliances with which they have a natural affinity (see
Luchenes, p. 691).

Discomycetes.—These, like the Pyrenomycetes, constitute a very extensive
family. They are characterized by the fact that when mature the structure bearing
the asci expands into a disc or cup, so that the ascal surface is exposed; or this
surface is spread over the outside of a fleshy receptacle.

As a good example of a Discomycete, the large genus Peziza may be cited.
They are met with chiefly on decaying vegetable matter, and in the various species
the dise or cup—the fertile receptacle—is sessile on the mycelium. Peziza vesi-
culosa (ef. fig. 388°) is one of the commonest British species, occurring in humus,
rotting leaves, &c. Its cups (the apothecia) attain a diameter of 2-3 inches, are
buff in colour, fleshy, and very fragile. The inside of the receptacle is everywhere
lined with the layer of asci, with sterile hairs, the paraphyses, between (it is similar
to fig. 388”). Another common species is P. scutellata; it forms little flat red discs
about the size of sixpenny-pieces upon rotting wood, and the margin is set with
hairs. Several of the Pezizas are stalked (cf. figs. 388° and 388%). P. eruginosa
is an interesting form; it also is stalked, and grows especially upon dead branches of
Oak. It permeates the wood with its mycelium, and this appears to excrete a green
pigment which stains the wood in its vicinity. The stalked apothecium is also
green in colour. This green-rotting wood is exceedingly common and is used in
the manufacture of “Tunbridge ware”; the actual Fungus, however, is by no means
so obvious, and from the majority of green-rotted branches not only has the apothe-
cium disappeared, but the mycelium also. Resembling a Peziza, but very gelatinous,
is Bulgaria inquinans, common on decaying trunks of trees. Peziza Willkommii,
causing the Larch-canker, has been already referred to (ef. p. 522). Nearly related
to the Pezizas, and causing parasitic diseases of plants, is Sclerotinia. It possesses
a well-marked sclerotium, from which stalked Peziza-like apothecia are produced.
A species not uncommon in this country is Sclerotinia tuberosa. It attacks the
underground parts of Wood Anemones and forms its sclerotia in the tubers of this
plant. In the spring, instead of Anemone-flowers coming up, the sclerotium gives
rise to a number of long-stalked apothecia which appear just above the surface of
the ground.

Other more complex Discomycetes are the Helvellas and Morels, forms purely
saprophytic. Helvella produces a stalked receptacle, curiously folded (see figs. 388 ®

THALLOPHYTA. 683

and 388") and plaited; the whole of the exposed surface of this receptacle is covered
with asci. The Morel ( Morchella esculenta, fig. 3881) possesses a thick stalk bearing
a large fleshy receptacle marked out in pitted areas. Nearly allied is the genus
Geoglossum, possessing club-shaped receptacles, black in colour, and covered with
asci. G. difforme, 2-4 inches high, is often met with among grass in the autumn.

The Lichenes belonging to this family are treated with the other Lichens
at p. 691.

Reference to a small group of forms, the Saccharomycetes or Veasts, may be

Fig. 388.—Discomycetes.

1 The Morel (Morchella esculenta). 2 Vertical section of the fertile surface of the Morel showing five asci with their spores
and filamentous paraphyses between the asci. 8 Peziza (Helotium) Tuba. + Anthopeziza Winteri. 5 Peziza vesiculosa.
6 Helvella infula. 7 Helvella jfistulosa. 1,4,5,6,7 nat. size; 3x4; 2x 120,

introduced here. They constitute a detached family with ascomycetous affinities,
and characterized by their very peculiar mode of life. For the most part they
do not form mycelia, but increase by budding and by the formation of spores.
Saccharomyces cerevisew is the well-known Brewer's Yeast. The cells are oval and
colourless, and provided with one or more conspicuous vacuoles; the cell-nucleus is
not readily demonstrable, though there is little doubt of its existence. Growth
here is by budding, little processes being pushed out at the periphery at one or more
spots and gradually enlarging (figs. 387+5°); ultimately they are cut off from the
parent-cell by the completion of the membrane across the point of union. In this

684 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

way groups of cells may hang together in chains (fig. 387°) for a short time, but
they disarticulate sooner or later. As the substratum becomes exhausted the cells
exhibit a tendency to form spores in their interior (2-8), the cell being as it were
transformed into an ascus (fig. 3877). The special physiological activity associated
with this and several other species is alcoholic fermentation (cf. vol. i. p. 506), 4.e.
the splitting up of sugar into alcohol and carbonic acid. S. cerevisew is used in
brewing, S. ellipsoideus causes the fermentation in the juice of the Grape.
S. mycoderma forms a scum on wine and beer, and is of
interest in that it produces mycelial tubes.
In all there are some 40 species of Saccharomyces.

Alliance XIX.—Basidiomycetes.

Parasites and saprophytes, reproducing by means of conidia
which arise on basidia in definite number. Besides these
characteristic conidia there are subordinate fructifications.:

Families: Uredinee, Auriculariacee, Tremellacew, Pilacracee,
Dacromycetes, Hymenomycetes, Gasteromycetes.

The Basidiomycetes are an exceedingly large alliance, and
include forms from the simplest to the most complex. They
all agree, however, in the production of conidia from a definite
basidiwm, a character which gives its name to the group. As

Big. 389,
‘Portion of a lamella of an has been already pointed out (p. 674) there are two families

Agaricus with a basidial =; : sqee a : 5 :
layer(fromwhichconidia. +12 the Hemibasidii, 2.e. the Ustilaginacese and the Tilletiaces.

are being budded off) x +45 eas
on tithe side san Im both families a promycelium or basidium arises from the

three basidia, more high- Chlamydospore; in the former it is septate and conidia are cut
ly magnified, from the .

basidial layer of the same off laterally, in the latter it is non-septate and the conidia are
cnbied soatwre produced in a tuth ab the extremity. In the Urediner a
ron oe saneriemata). —_basidium arises from each cell of the teleutospore (the probable
equivalent of a chlamydospore), and this basidium is trans-

versely septate, four cells being cut off at the end of the tube away from the spore.
Each of these cells produces a little process, and from each process a conidium is
abstricted. In all the other families of Basidiomycetes the teleutospore (or chlamy-
dospore) is suppressed, and the basidia are directly continuous with the hyphe of
the Fungus. Otherwise, the basidia of Auriculariacese, Tremellacess, and Pilacraces,
all belong to the type of the Uredinex, and are derivable from the Ustilago-form.
On the other hand, the basidia of Hymenomycetes and Gasteromycetes, and
probably also of Dacromycetes, belong to the Tilletéa type (¢f. p. 675). The conidia
do not arise laterally, but from four processes at the tip of an unsegmented basidium
(see figs. 389° and 3907). The very general restriction of the number of processes

arising on the basidium to four is without doubt a feature of some importance, and

THALLOPHYTA, 685

is a further justification for the inclusion of all these families—at first sight so
different—in a single alliance.

Uredinece.—These are the Rust-fungi, parasites for the most part on the foliage
of higher plants. They are outwardly manifest in the form of yellow or brown

alent
sy,

Fig. 390.—Basidiomycetes.

1Clavaria aurea, 2 Deedalia quercina. *®Marasmius tenerrimus. 4Marasmius perforans. § Craterellus clavatus. 6 Amanita
phalloides. 7 A portion of the basidial layer of the last-named Fungus showing the sterigmata and conidia. %* Hydnum
imbricatum. 9% Polyporus perennis. 7™X250; the rest nat. size.

spots and streaks, due to the spores, which are formed in masses on the surface.
The mycelium inhabits the intercellular system of the host-plant, and draws its.
nourishment from the living cells. The spores are regarded as chlamydospores, that
is to say, localized, thick-walled segments of the hyphe having the properties of
reproductive cells. These spores are met with in three forms in the Uredinew. The

686 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM

Telewtospores (from redevr}, an end), which are the type most universally present, arise
towards the end of the vegetative period. In the majority of cases they remain
dormant during the winter. On germinating they form a 4-celled basidium, from
each cell of which a conidium is abstricted. Commonly the teleutospores are in
rows of two, «.¢. constitute spindle-shaped, 2-celled bodies, each cell (spore) of which
can produce a basidium. Sometimes the teleutospores are in many-celled rows,
occasionally solitary. The Uredospores (from wro, to burn) as a rule precede the
teleutospores and germinate at once. They are oval and unicellular. The £cidio-
spores arise in chains in special receptacles (the ecidium-fruits) which are at first
closed. . Both uredospores and ecidiospores differ from teleutospores in that they
produce a mycelium at once on germination. They never form basidia and conidia.
A fourth sort of reproductive organ, a secondary conidial stage, is often found
associated with the ecidium stage; this is the pycnidium (cf. p. 678), a hollow
receptacle whose lining cells abstract tiny condia. The fate of these pyeno-conidia
and the part they play in the life-history of the Fungus is unknown.

There is thus in the Uredinee great variety in the kinds of reproductive cells.
Some species possess all of them and produce them one after another upon the same
host-plant (e.g. Puceinia gala and P. primule); others possess teleutospores only
or teleutospores and one of the other types, whilst in others again all the forms are
present, but they are not developed upon the same host-plant. This latter property
of developing the different stages on two host-plants (known as heterecism) is
by no means uncommon amongst the Uredines. It is remarkable enough to merit
a short description here, though, of course, any exhaustive account of the family as
a whole is impossible. The following are well-known cases of hetercecism. Coleo-
sporiwm senecionis, which produces its uredospores and teleutospores on the
Groundsel (Senecio vulgaris), its wcidiospores on Pinus sylvestris (the latter stage
formerly known as Peridermium pint); Puccinia graminis, which produces its
uredospores and teleutospores on Wheat and other grasses, its eecidiospores on the
Barberry (this stage formerly known as Acidium berberidis); Gymnosporangiwm
junipervnum, which produces its teleutospores on the J uniper, its ecidiospores on
the Mountain Ash (Pyrus aucuparia). These three may serve as types of a very
large number of similar forms. Puccinia graminis, the Rust of Wheat, is the most
famous of all. The xcidium-stage (accompanied by pycnidia) arises in spring on
the foliage of the Barberry and the ecidiospores here produced cannot germinate
on the same host, but only on Wheat, Oats, Rye, or some other Grass. Here a new
mycelium is established bearing first uredospores and later on teleutospores. The
uredospores can germinate at once on other grasses, but the teleutospores remain
dormant through the winter, and in spring give rise to basidia from which conidia
are abstricted; these conidia can germinate only on the Barberry—not on grasses—
and from the mycelium which arises from them fresh ecidium-fruits are developed.
In the absence of either host-plant (i.e. of the Barberry or of suitable Grasses) the
life cycle of the Puccinia is of course interrupted. For the extermination of the
Rust disease of cereals the removal of Barberry bushes is an obvious measure. In

THALLOPHYTA. 687

parts of Europe, however (¢.g. many upland valleys in Switzerland) this precaution
is not taken and the cidiwm-covered Barberries and rusted crops may be seen
standing side by side. It is true the rust does not destroy the wheat crop entirely
but it seriously diminishes the yield of grain. Long before the life-history of the
Rust-fungus had been scientifically traced the Barberry was known to have an
evil influence upon cereals. So long ago as 1760 the state legislature of Massa-
chusetts passed an Act’ compelling the inhabitants to extirpate all Barberry bushes.
The main facts connected with the life-history of Gymnosporangiwm have already
been mentioned (¢/. p. 522), and the two stages are represented on p. 521. The
projecting lobes on the Juniper (fig. 3571, page 521) consist of masses of teleuto-
spores embedded in mucilage. When wetted they swell up, the basidia are pro-
duced and the conidia abstricted; the latter are then blown away and, should they
alight upon the young foliage of a suitable member of the Pomacew, penetrate the
tissues and produce the Aicidiwm stage. The effects of various other members of
this group are referred to on pp. 524, 525. Between four and five hundred parasitic
Uredinez have been distinguished.

Auriculariacee. — Include the well-known Jew’s-ear Fungus (Auricularia
sambucina) not infrequent on dead branches of the Elder. From its fertile surface
basidia with conidia resembling those of the last family are produced, but the
basidia are continuous with the hyphe of the Fungus, no chlamydospores being
produced ‘

Tremellacece—Gelatinous forms found on rotting tree-trunks. Their substance
is curiously lobed and plaited; Tremella Mesenterica, which forms large gelatinous
orange masses on dead branches, is the commonest of them.

Pilacracee.—Include a single genus only, Pilacre; it grows on Beech-bark,
and consists of a spherical head mounted on a stalk. It is of interest because its
basidia (from which the conidia are abstricted) are inclosed in a loose layer of
hyphe—the outward continuations of the hyphe upon which the basidia are
borne—and it is thought to lead on the family of the Gasteromycetes, in which the
basidia are entirely covered in.

Dacromycetes.—Gelatinous forms resembling the Tremellacew. They approach
the Hymenomycetes in that their basidia are destitute of septa. The processes
from which the conidia are abstricted are very long. Dacromyces deliquescens is
common as a red-coloured tough gelatinous mass on wooden palings.

Hymenomycetes—An extensive family characterized by the production of a

1 THE BaRBERRY Law oF MAassAcHUSETTS.—Anno Regni Regis Georgii II. Vicesimo Octavo, Chap. X.
(published January 18, 1755).

An Act to prevent Damage to English Grain arising from Barberry Bushes.

Whereas it has been found by experience, that the Blasting of Wheat and other English grain is often
occasioned by Barberry Bushes, to the great loss and damage of the inhabitants of the Province :—

Be it therefore enacted by the Governour, Council, and House of Representatives, that whoever, whether
community or private person, hath any Barberry Bushes standing or growing in his or their Land, within any of
the Towns in this Province, he or they shall cause the same to be extirpated or destroyed on or before the
thirteenth Day of June, Anno Domini One Thousand Seven Hundred and Sixty. And so forth. (From Plow-
right’s British Uredinee. )

688 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

fertile surface (the hymeniwm) consisting of basidia with 4 processes (or sterig-
mata) from each of which a conidium (or basidiospore) is abstricted. Typical
basidia are represented in fig. 389°, p. 684, and fig. 390°. The hymenium in this
group is exposed at the time when the basidiospores are produced.

As in the Ascomycetes, so here, there is an extensive range of forms from simple
to complex. Simplest of all are the Haobasidew, mostly parasites on Ericacez.
Exobasidium Rhododendri, which causes the Alpine Rose apples, has already been
mentioned (p. 520), as also EZ. Vaceinit and E. Lawri (p. 526). The hymenium in
these simple forms is produced over the whole surface of the hypertrophy or
blister caused by the Fungus. In the Telephorew a definite tissue bearing the
hymenium is developed; this is termed the hymenophore or fructification. In the
simple Corticiwm this forms smooth sheets of waxy nature everywhere encrusting
the substratum. The basidia occur over the free surface. Sterewm; also very
common on old trunks, forms leathery plates usually attached laterally or stalked.
The hymenium is on the smooth under surface, whilst the upper surface of the
fructification is more or less velvety. Craterellus (fig. 390"), laterally attached, is
hollowed out above; the under surface is the fertile one. In the Clavariw the
fructification is club-shaped and fleshy, and covered externally by the hymenium—
as in the sulphur-yellow Clavaria inequalis very common on grass lawns and
pastures—or it is branched and coral-like as in Clavaria aurea (fig. 390"). In the
Hydnew there is a well-marked distinction into a stalk and cap (known as the
ileus); the hymenium is on the under surface, and-is in the form of a number of
crowded spines or teeth (e.g. Hydnum imbricatum, fig. 3908). The Polyporee form
a large and important group, characterized by the fact that the hymenium has the
form of a number of pits, tubes, or meshes, usually on the under surface of the
fructification. The simplest of these is the Dry-rot Fungus, Merulius lacrymans.
The mycelium of this Fungus penetrates the substance of ill-preserved woodwork
in houses, disintegrating it and reducing it to a brittle consistency. At places it
produces fructifications, flat irregular bodies whose under surface, the hymenium,
consists of a honeycombing of shallow depressions. The property which these
fructifications possess of excreting drops of water has given to this Fungus the
name lacrymans. In Polyporus the hymenium has the form of numerous fine
tubes lined with basidia. The fructification may be either bracket-like, as in
Polyporus fomentarius (growing on the Beech-trunk to the right hand of Plate
XIV.), or it may have the cap-like form of a mushroom mounted on a central
stalk, eg. P. perennis (fig. 390°) and the allied Boletus edulis (Pl. XIV. left-hand
bottom corner). To these Polyporuses belong some of the most destructive diseases
of timber, their myceliums penetrating the wood everywhere, softening and
disintegrating it (e.g. Polyporus igniarius, P. fomentarius, P. sulphureus, and
P. annosus—otherwise known as Trametes radiciperda). The last-named P.
annosus causes a well-known disease of coniferous timber, the wood coming out
in white spots before it is finally disintegrated. It is of interest because the
fructifications are produced on the roots of the trees attacked. Allied to Polyporus

THALLOPHYTA. 689

is Dedalia (fig. 390*) a bracket-like form in which the hymenium takes the form
of irregular branching slits on the under surface. The Agaricinew, which include
the very numerous mushroom and toadstool Fungi, are for the most part umbrella-
like in form, having a central stalk and expanded circular receptacle (the pileus).
The under surface of the pileus is occupied by lamelle or gills which radiate from
the insertion of the stalk to the margin of the pileus (¢f. figs. 3903+). The
basidia forming the hymenium are set upon the sides of these gills. Fig. 3891
shows an enlarged section through a part of a gill) In the more complex forms.
certain structures are present inclosing the young fructification, but they are
ruptured as the pileus expands, and in adult fructifications the gills are freely
exposed. Their remains may often be seen on the mature Fungus, as in Amanita
(fig. 390°). Just below the pileus there is a membranous ring (the annulus); at:
an earlier period it was attached to the margin of the pileus covering in the
hymenium, and forming what is termed the velwm partiale. In the same Fungus.
may be noted the remains of another sheath, the velum wniversale, which en-
wrapped the entire fructification. This is shown in fig. 390° as a ruptured sheath
(the volva) at the base of the stalk, whilst portions of the covering which invested
the pileus (and was continuous with the ruptured sheath alluded to) are to be seen
as white felty patches on the scarlet pileus of Amanita muscarius (cf. Plate XIV.).
The forms and varieties of the Agaricinexw are far too numerous even for mention.
Many of them are edible, notably the Mushroom, Agaricus campestris, and the
yellow-coloured Cantharellus cibarius (allied to the Agaricines, Plate XIV. on the
left). Others again are poisonous, as, for instance, the scarlet Amanita muscarvus
(Plate XIV.), which receives the name muscarius from the fact that decoctions of
this Fungus were formerly used for killing flies. Certain forms (Russula and
Lactarius) contain a latex of a white or yellow colour. A number are character-
ized by producing sclerotium-like bodies (cf. p. 681). Asa rule in the Agarics the
fructifications arise directly from the mycelium, but in Coprinus stercorarwus,
Lentinus, &¢c., tuber-like masses of fungal substance are formed, and it is from
these that the fructifications arise. These sclerotia, often attaining large dimen-
sions, have been found by travellers in various parts of the world, and the fructifi-
cation which arises from them is not in all cases known. Several of them, formerly
name Pachyma, &., are now known as belonging to the genus Lentinus. Very
curious are the string-like sclerotia of Agaricus melleus which, from their root-
like nature, were formerly termed “Rhizomorphs”. They are found especially in
Conifers, growing between the wood and bark, and having a ribbon-like form; from
them cylindrical branches may arise which penetrate the soil and attack the root of
some other tree. Ultimately the mushroom-like fructifications arise from these
rhizomorphs.

A few lichens derived from the Hymenomycetes are treated at p. 695.

Gasteromycetes.—These are characterized by the fact that the basidia arise in
closed chambers, which collectively constitute the gleba, and that this is covered by

a continuous cortex or peridiwm. They include the Puff-balls, Earth-stars, Stink-
Vou. IL. 94

690 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

horns, &. They are all of them more or less subterranean saprophytes, appearing
above the surface to discharge their spores. The arrangements for the accomplish-
ment of this purpose are very varied. The Puff-balls include the genera Lycoper-
don, Bovista, Scleroderma, &e. When young a large portion of the interior has a
chambered structure (the gleba), and in these chambers the spores are budded off.
At maturity the fructification appears above the surface of the ground, and the
whole of the substance of the walls of the chambers breaks down, except for certain
branching threads (the capillitiwm, see fig. 391 8), which persists along with the

Fig. 391.—Gasteromycetes.
1 Lycoperdon constellatum. %Tulostoma mammosum. 3 Capillitium and spores of Tulostoma, 4 Geaster multijidus. * Geaster

fornicatus. © Cyathus striatus. 7 Longitudinal section of same. § Clathrus cancellatus. %x80; 7 slightly enlarged; the
rest nat. size.

minute spores (Scleroderma has no capillitium). The latter escape by the peridium
becoming perforated. Lycoperdon (see fig. 3911) differs from Bovista in having a
sterile basal portion, which is sometimes considerably elongated. In Tulostoma
(fig. 3917) the outer layer of the peridium bursts and the sterile basal portion
elongates considerably, hoisting up the gleba inclosed in an inner peridium. The
Giant Puff-ball (Lycoperdon gigantewm) sometimes attains huge dimensions—
occasionally a metre in diameter. Allied to the Puff-balls is Geaster, the Earth-star
(figs. 391* and 391°). In this genus the outer peridium splits into segments and
folds back, the inner peridium becoming perforated and liberating the spores.
Earth-stars are met with now and then, but they are not usually very common.
In Cyathus (figs. 391° and 3917) we have a form resembling a little bird’s-nest

THALLOPHYTA. 691

containing eggs. Here the chambers, instead of being numerous and deliquescent
as in Lycoperdon, are few and provided with thick, hard walls; they arise in a
matrix which occupies the whole body of the Fungus, and when mature they
become isolated by the disappearance of the matrix. Each chamber is attached
by a string to the wall of the peridium (¢/. fig. 3917). The opening at the top
arises by the coming away of a membrane which previously closes it in. Perhaps
the most remarkable group of Gasteromycetes is the Phalloidew, which includes
the common Stink-horn Fungus and other forms. Whilst immature they are egg-
like, but at ripening the investment bursts and the remarkable gleba is hoisted up.
Clathrus (shown in fig. 391°) has its gleba spread over a hollow spherical lattice-
work; the gleba is red in colour and the appearance of the Fungus very striking;
it is rare in this country. The Stink-horn, Phallus impudicus, is less rare. When
the gelatinous investment bursts, a spongy, spindle-shaped stalk expands and raises
up the green, cap-like gleba. The Phalloidew depend upon insects for the dispersal
of their spores. Flies are attracted by the bright coloration and foul smell of these
Fungi, and they lick up the mucilage into which the gleba deliquesces with great
avidity. Perhaps the tropical Dictyophora phalloidea is the most remarkable of
the group. It resembles a Phallus, but unfolds around itself a delicate white
network which hangs expanded from below the gleba-cap like a crinoline. It is
thought that this appendage—like the white corolla of a night-flowering plant—
renders the Fungus additionally conspicuous after dark. The Phalloides, in re-
ference to their marked attraction for insects, are sometimes spoken of as the
“Flowering Fungi”.

ADDITIONAL GROUP OF FUNGI.

LICHENES.

In our review of the various alliances and families of Fungi the fact has been
from time to time noted that certain members of various groups live symbiotically
with Algz as Lichens. Though obviously all these Lichen-fungi do not constitute
a natural group or alliance, we propose treating them for convenience together.
The general characters of Lichens and their mode of life have been already indicated
in the chapter commencing at vol. i. p. 248; consequently little but an enumeration
of the groups of Lichens and their methods of reproduction is required now. Briefly,
a Lichen consists of a Fungus and an Alga upon which the Fungus lives parasitically.
But it is something more than a mere parasitic Fungus on a green plant. The
mycelium involves the Alga in the most complete manner (cf. fig. 392), but it doesn’t
kill it like an ordinary parasite. It lives upon the organic food which the Alga is
able to manufacture in virtue of its chlorophyll, but without obvious injury to the
Alga. Indeed, the algal cells often attain to a larger size and greater brilliance of
colour than when growing freely. On the other hand, the Alga is nowhere in contact
with the substratum (being inclosed in the substance of the Fungus), so that water

692 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

and dissolved salts are absorbed and supplied it by the Fungus. It is also protected
by the Fungus, and able to exist in places where it could not live alone. Thus,
for the Lichen, we speak of symbiosis, a living together. “Tis true the Fungus is
the predominant partner in this association, but it is not a parasite in the common
acceptation of that term. Further, as predominant partner it is the Fungus which
determines the form of growth and takes the initiative, the Alga following after.
But even to this rule an exception has been found, and very likely others exist.
For where two organisms live together, as in the Lichen, it may well happen that
conditions may exist under which the Fungus can only control the Alga with
difficulty, and that the Alga, attempting as it were to escape, compels the Lichen-
fungus to follow it, not to lead. This indeed seems to be the case in one of the
forms of that most remarkable of all Lichens, Cora pavonia, to be referred to
below.

The conception of the Lichen as a dual organism, compounded of Fungus and
Alga, is of relatively modern origin. Its establishment is due to the researches of
Schwendener, which date back some thirty years, and to those of Bornet, which
shortly followed them. Since those days the continued study of Lichens has tended
only to secure for the “Schwendenerian theory” (as it was formerly termed) a
more wide and universal recognition. Previous to the Schwendenerian epoch the
Alga was regarded as a definite portion of the Lichen-thallus, its cells as arising
from the hyphex of the Fungus; indeed the Alge were termed “ lichen-gonidia”.
And for many years was the new view opposed by the majority of professed
Lichenologists; but into this old controversy we have not space to enter here. It
is sufficient to say that the Alge of Lichens are referable to known genera and
species of free-living Algw, and that they have been determined for a number of
cases. The Alga freed from the Lichen-fungus pursues its normal mode of life, and
can then be identified; this is not always possible so long as it remains within the
Lichen, owing to the change which the Fungus calls forth in it. It is a noteworthy
fact that hitherto no Alga has been found so completely adapted to lichenism that
it could not attain to its normal development outside the Lichen-thallus. On the
other hand, Lichens have been raised from the spores of the Lichen-fungus allowed
to germinate on free-growing Alge. In this way a number of Lichens have been
synthesized; and it has been shown that one and the same species of Alga could
serve for several Lichens. Finally, the spores of Lichen-fungi have been grown on
nutrient solutions, and have attained to advanced stages of development. In
nature, however, with one exception (Cora, see below), it is not certainly known
that any Lichen-fungus can grow independent of its Alga as substratum. We
must regard the Lichen-fungi as being members of various Fungus-families which
have become so specialized to a peculiar form of nutrition that under ordinary
circumstances they do not develop upon anything except their Alga. The Fungus-
forms which occur in Lichens are vastly more numerous than are the Algw; indeed
the latter are drawn from relatively few families—from the Chroococcaceew and
and Nostoccacez of the Blue-green Algz, and from the Protococcoidex, Confervoidex,

THALLOPHYTA. 693

and Coleochestex of the class Gamophycew of Green Algw. Thus the same Alga
serves for many different Lichens.

Classifying Lichens according to the characters of the fungal constituent, we
find members of the following families: Discomycetes, Pyrenomycetes, Hymeno-
mycetes, and Gasteromycetes. We may therefore speak of 4 families of Lichens:

Discolichenes, Pyrenolichenes, Hymenolichenes, and Gasterolichenes.

Discolichenes.—All produce asci in apothecia after the manner of Discomycetes
(cf: p. 682), The apothecia arise in numbers on the surface of the Lichen-thallus
(ef. figs. 393°, 394, and 387°), and the spores are formed in the asci in the usual
way. In many genera the spores are multicellular. In not a few cases there are
arrangements for the simultaneous distribution of the Alga-cells along with the

Fig. 392.—Lichens.

1 Hyphe of Stereocaulon ramulosum enveloping filaments of the blue-green Alga Scytonema; x650. 2% Cladonia furcata with
Prot 5 x950. 38 Ci “pia molybdcea, section of thallus; x650. (After Bornet.)

ascospores, so that it shall not be left to chance for the spores to alight upon a suit-
able Alga. In these cases the algal cells bud actively below the layer of asci, and
some are pushed up between the asci at the time when the latter reach maturity.
Many Lichens possess also conidial fructifications, known as pycnidia (cf. p. 678).
These are flask-like excavations, into which tiny conidia are budded by the lining
cells. These receptacles were formerly termed spermogonia and the conidia sper-
matia; but the evidence that they have any such function as the terminology sug-
gests is of the most slender description. On the other hand, these conidia have been
caused to germinate and produce characteristic Lichen-thalluses in a number of
cases. Pycnidia may be easily seen in the Iceland Moss (Cetraria islandica); they
occur one in each of the tiny teeth on the margins of the ribbon-like thallus. Very
common is vegetative propagation by means of brood-bodies known as soredia.
These arise as little buds below the surface, and consist of an algal cell or two and
a weft of fungal hyphe. Being formed in quantities together they burst through
to the surface as a dust-like powder and constitute the “soredia-heaps”. They are
distributed by the wind or washed away by rain. Both constituents of the Lichen

694 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

being present, they readily grow into fresh Lichens. In the majority of Lichens
the Algee are arranged in a definite layer or stratum (ef. figs. 392° and 3877); rarely
are they distributed through the whole thickness of the thallus, as in the Gelatinous
Lichens (Collema, fig. 393°). Apart from these Gelatinous Lichens, the Discolichenes
may be divided, according to their form, into Crustaceous, Foliose, and Fruticose
Lichens. Crustaceous Lichens include such as are everywhere attached to their
substratum (stones, bark of trees, &c.) and cannot be removed without injury. As
examples may be mentioned the Lecidias, many of the Lecanoras, &c. The Foliose
Lichens are not thus firmly attached; the thallus forms a shield- or ribbon-like
expansion, readily separable from its substratum, as, for instance, the well-known
orange Lichen Physcia parietina, the green-hued Peltigera canina (Pl. XV.), with

Fig. 393.—Gelatinous Lichens.

1 Ephebe Kerneri; x450. 2 Collema pulposum; nat. size. 3 Section of thallus of Collema pulposum, with Nostoc as Alga; x 450.

projecting umber apothecia, common in moist places amongst moss and stones,
Umbilicaria, and many others. In the Fruticose Lichens the plant is only attached
at one place, and has a shrub-like, branched appearance. Here are included many
elegant and well-known forms, including Usnea barbata, the Old Man’s Beard
Lichen (Pl. XV.), which hangs in tufts and festoons from the branches of trees,
and sometimes produces large disc-like apothecia the size of sixpenny pieces.
Another of these epiphytic forms is Ramalina reticulata, a Californian form which
forms beautiful gray-green, ribbon-like nets. Nor must Cetraria islandica, the
Iceland Moss (Pl. XV.), and the Cladonias be omitted. The last-named are glaucous
and generally erect-growing and branched. They include Cladonia pywidata, the
familiar Cup-moss (Pl. XV.), C. rangiferina, the Reindeer-Moss (Pl. XV.), and C.
coccifera, growing on heaths with its scarlet, and C. macilenta (Pl. XV.), with orange
apothecia.

Pyrenolichenes.—In these the asci are contained in perithecia as in the Pyreno-
mycetes (cf. p. 678). Otherwise they are in general agreement with the last
group, and include crustaceous, foliose, and fruticose forms. There are only a

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FRONDOSE AND FRUTICOSE LICHENS

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THALLOPHYTA. 695

few genera of Pyrenolichenes, including Verrucaria, Eyphebe, Endocarpon, and
Spherophorus.

Basidiolichenes.—These occur only in tropical countries, and a number of genera
were formerly distinguished, including Cora, Dictyonema, and Laudatea. Cora
pavonia, the best-known form, consists of a greenish-yellow, fan-like, concentrically -
striated thallus which produces its basidia on the under surface and contains Chroo-
coccus-cells as its Alga; Dictyonema, on the other hand, consists of thin plates of
rather felty consistency, in which the radiating character of the strands is very
apparent; these delicate plates, blue-green in colour, stand out from the tree-branch
to which they are attached. Laudatea, though resembling Dictyonema, is a crus-
taceous form. Both the latter forms have Scytonema-filaments as Alge. Quite

Fig. 394.—Lecanora esculenta.

recently it has been shown by A. Miller, a naturalist who resided several years in
Brazil, that all these supposed distinct Lichens are different growth-forms of one
and the same Lichen. In addition to finding each of these forms in connection
with the other—so that there is no doubt of their continuity—he found attached to
the Cora-form the Fungus growing free from all trace of the Alga; this Fungus is
one of the Telephorez (cf. p. 688), and when it is supplied with Chroococcus-cells
grows into the Cora-form, This seems to be the only well-ascertained instance in
which a Lichen-fungus has been found growing wild independent of an Alga. The
Dictyonema- and Laudatea-forms consist of the same Fungus growing upon Scyto-
nema instead of Chroococcus. In the Lawdatea-form the Alga seems to get the
upper hand and to determine the growth of the thallus. Cora and its various
growth-forms is certainly the most interesting, as it is also the most beautiful of all
Lichens of which we have any knowledge.

Gasterolichenes——A Lichen from the Gasteromycetes has also been recognized; it
is a little, shortly-stalked, puff-ball-like form resembling a Lycoperdon (cf. p. 690).
The Alga (a Palmella) is restricted to the peripheral portions of the Lichen, which
is named Hmericella variecolor.

696 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

PuyLtum 3.—ARCHEGONIATA.

Plants showing a well-marked alternation of generations, that is of a sexual
(oophyte) and an asexual generation (sporophyte). The latter reproduces the
former by means of spores, the former the latter by means of egg-cells contained in
archegonia. Fertilization is by means of spermatozoids which swim in water.

Class I—BRYOPHYTA.

The sexual generation is in the greater number of cases a leafy shoot, arising
from a branched, filamentous protonema. The asexual generation, which arises
from the archegonium, is a stalked or sessile capsule containing spores; it is
destitute of leaves, and never becomes independent of the oophyte.

Alliance XX.—Hepatice, Liverworts.

Oophyte nearly always dorsi-ventral; either thalloid or leafy. Protonema incon-
spicuous. Sporophyte a stalked or sessile capsule containing spores and usually
elaters. A calyptra is not present.

Families: Ricciacee, Marchantiacee, Antherocerotacew, Jungermanniacee.

The oophyte generation in the first three families is a branched, ribbon-like, or
lobed thallus (cf. fig. 1961, p. 23), showing a distinction between its upper and lower
surfaces, 1.¢. is dorsi-ventral. In the Jungermanniacee it is likewise thalloid in some
forms, but in the great majority the oophyte has the form of a leafy shoot. The
oophyte communicates with the substratum by means of rhizoids. The complete
oophyte is preceded by an inconspicuous filamentous growth, the protonema, which
arises directly from the spore, but this stage is not so well marked as in the Mosses.
The sexual organs are borne usually in groups either in little depressions or upon
special outgrowths of the thallus, or, in the leafy forms, are collected together into
little “ flowers” at the tips of the shoots or in the axils of the leaves. The female
organs or archegonia are flask-shaped bodies with long necks, as in mosses. The
egg-cell is contained in the enlarged basal portion, and on fertilization develops into
the sporophyte or spore-capsule. The antheridia are delicate, stalked, oval or club-
shaped bodies in which the 2-ciliate spermatozoids are developed. They resemble
those of Chara, shown in fig. 3747 (p. 660). The spore-capsule develops within the
archegonium ; its lower portion (in all but the simplest cases) forming a “foot” or
sucker which remains imbedded in the substance of the oophyte, its upper portion
forming the capsule proper. In many forms, particularly in the Jungermanniaces,
a stalk is developed between foot and capsule, so that the latter is ultimately hoisted
up. The capsule does not burst through the archegonial wall until the spores are
ripe, nor is a portion of the archegonium raised up as a cap on the capsule as
happens in the Mosses. The capsule ultimately opens by splitting into valves. In
nearly all cases elaters are present with the spores. They are long thread-like cells
with spiral thickening of the wall, and as they dry become very hygroscopic and

BRYOPHYTA, 697

contractile. They assist in the dispersal of the dust-like spores in many cases,
though the details of their co-operation in this respect is not always the same.
Before the ripening of the spores the elaters play an important part in the nutrition
of the spores; they are sterile cells or filaments intermixed with the spores to which
they conduct food-substances during their development. Attention has been
already drawn to the brood-bodies or thallidia of Liverworts (of. p. 24).
Riccvacece—These are very simple little forms occurring in wet places or floating
in water (Riccia natans) like a Duckweed. The thallus is lobed or it may be
ribbon-like and branched. The sexual organs are sunk in little chambers on the
upper surface of the thallus; antheridia and archegonia may occur on the same or
on different individuals. The fertilized egg-cell is here entirely converted into a
spore-capsule, z..a sheath inclosing spores. No elaters are present in this family,

1 Vertical section through an air-chamber of the Liverwort Marchantia polymorpha showing the stomate-like pore and the
assimilating filaments. * Transverse section of a leaf of a Moss, Barbula alotdes, showing the projecting plates of cells.
1x 300; 2x 380.

nor is there a sterile base or foot. The genus Riccia includes 107 species; there are
110 species in the whole family.

Marchantiacew.—The oophyte is a lobed band-like thallus (cf. fig. 1961, p. 23)
with marked dorsi-ventrality. On the upper surface are a number of chambers each
opening to the exterior by a single stomate-like pore (Marchantva, fig. 395"). These
chambers are really excavations of the upper surface which become closed in
save for the pores in question. From the floor of each chamber sprout filaments of
chlorophyll-containing cells (fig. 3957); these form the main assimilating tissue of
the thallus. In Marchantia and Lunularia brood-bodies (or gemmee) are budded
off in cup-like receptacles (cf. fig. 1961, p. 28). The sexual organs in this family are
borne on special receptacles on the upper surface of the thallus. These may be
either shield-like or stalked and umbrella-like (as in Marchantia, Fegatella, &c.).
The male and female. organs respectively occur on separate receptacles and are
variously arranged. There are special sheathing structures associated with the
archegonia. The sporophyte generation or sporogonium has a sterile base or foot
which remains embedded in the archegonium. The spore-capsule is joined to the
foot by a narrow, isthmus-like neck. The capsule opens by splitting into teeth.
Elaters are present. Considerable variety is shown in this family in the form of the
receptacles of the sexual organs.

165 species have been distinguished.

.

698 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Antherocerotacee.—The oophyte has the form of a little lobed dise, in depres-
sions of the surface of which the antheridia and archegonia are sunk. The sporo-
gonium is long and cylindrical, and is invested in a circular sheath at its base. The
spore-layer has the form of a hollow cylinder, leaving a sterile, central strand of
tissue (the columella). Elaters are present amongst the spores, and serve as
nutritive tissue for them rather than as instruments of dispersal. In this group

Fig. 396.—Jungermanniacez.

1 Frullania dilatata growing on the bark of an Acer. 2 A small portion of this plant enlarged; it shows the stalked spore-
capsule burst into four valves; attached to the valves are the elaters. % A shoot of the same Frullania seen from the
under side; at the base of each leaf is a little pitcher containing a Rotifer. The little toothed scales lying on the stem are
the amphigastria. 4A single pitcher and its contained Rotifer. § The Rotifer (Callidina symbiotica) removed from the
pitcher. 1 nat. size; 2x20; 8x25; 4x30; 5x 100.

—alone amongst the Liverworts—stomates occur upon the spore-capsule. It
dehisces into two valves.

There are 103 species.

Jungermanniacee.—ineclude both thalloid forms, in which the oophyte genera-
tion has a general resemblance to that of a Marchantia, and creeping leafy forms
(cf. fig. 3961); the latter are by far the more numerous. The sporogonium in both
eases consists of a long-stalked capsule which splits into four valves (fig. 396).
Elaters are present, often attached to the capsule-wall. The Jungermanniaces
grow for the most part on damp earth, stones, and bark of trees. ‘

The thalloid forms include the very common Pellia—like a Marchantia, with

BRYOPHYTA, 699:

long-stalked capsules inserted on its thallus— Metzgeria, branched and ribbon-like,
the curious aquatic Riella with its spiral membrane (see fig. 366, p. 611), and the
rather complex Symphyogyna and Pallavicinia (chiefly tropical), with their
creeping rhizomes and stalked fronds; these two forms, almost unique amongst the
Liverworts, show a well-marked vascular system. The antheridia and archegonia
are scattered over the surface of the thallus and not on stalked receptacles as in the
Marchantiaces.

The leafy forms are very numerous and, as a rule, consist of branched axes.
which lie parallel to the substratum (e.g. Frullania dilatata, fig. 3961). There are
three rows of leaves, two towards the upper surface and one towards the lower.
These ventral leaves, which are termed amphigastria, are tiny and scale-like (see
fig. 396°), and sometimes are only represented by hairs. The archegonia are usually
borne in little groups at the tips of the main or lateral shoots, and are inclosed
in involucres. The antheridia occur in various positions. The sporogonium is.
always a long-stalked capsule as in the thalloid forms. Not a few of the leafy
Jungermanniaceze produce curious little appendages or “auricles” at the bases
of their leaves, and these are often developed into little pitchers (fig. 396°). In
other cases the amphigastria bear pitcher-like appendages of the same kind. These
structures seem to be receptacles for the holding of water by capillarity against
times of drought. In some forms Rotifers inhabit these pitchers (e.g. Frullania
dilatata, figs. 396 * and 396°), but there is no evidence to show that the Liverwort
uses their bodies as food like ordinary pitcher-plants, or that any special relations
exist between the Rotifers and the Liverwort. The pitchers are not gall-structures
directly produced by the Rotifer—they develop equally well with or without them.
They are probably formed by the plant simply for storing water, and are found by
Rotifers and other small animals to be convenient abiding-places.

There are more than 3500 species of Jungermanniaceze

Alliance XXJ.—Musci, Mosses.

The oophyte generation is the leafy moss-plant; it arises as a lateral bud from
the simple and generally filamentous protonema. The sporogonium has a seta and
spore-capsule, the latter usually possessing a central sterile mass of tissue, the
columella. The upper portion of the archegonium is often raised as a calyptra by
the elongating sporogonium.

Families: Sphagnacece, Andrecacew, Archidiacew, Bryacec.

Sphagnacece.—These are the Bog-mosses, and they include a single genus,
Sphagnum. The form of the protonema here depends on whether the spore ger-
minates in water or upon a solid substratum; in the former case it is branched and
filamentous, in the latter it is a cellular expansion, not unlike a fern-prothallium.
The leafy moss-plant arises by budding from the protonema, and is remarkable on
account of its water-retaining properties. The character of the leaves has been
already described and figured at vol. i. p. 219. The sexual organs arise on special

700 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

shoots at the apex of the plant (fig. 397"); these shoots are respectively male and
female, and may occur on the same or on different plants. The antheridia are
in the axils of the leaves of the male shoots, the archegonia in groups at the tips of
the female shoots. The fertilized egg-cell develops into the sporogonium, the lower
portion of which forms a large foot, whilst the upper part swells up into the spore-

emma: Be
ee gfe

fi

Fig. 397 —Mosses.

1 Polytrichum commune ; the spore-capsule to the left is concealed by the cap (calyptra), that to the right is exposed. 2 The
same moss in an earlier stage of development. % Spore-capsule of Polytrichum commune with its lid. 4 The same after
the falling away of the lid. 5 Brywm cespiticium. 6 Spore-capsule of same with its calyptra. 7 The same after removal
of the calyptra. ® The same after removal of the lid, showing the teeth (peristome). 9 A portion of the peristome
enlarged. - 10 Antheridia, archegonia, and paraphyses of Bryum spitict 11 Hyl i lend 12 Spore-
capsule of same. 18 Andreea rupestris with burst spore-capsule, 14 Sphagnum cymbifolium ; the spore-capsules are
An “ek in the left-hand specimen. 15 A single capsule of the same. 1, 25, 11, 14, natural size; % 4, 4, 7, 8, 12, 18, 15 x5;

capsule. The spore-layer in the latter has the form of a hemispherical shell. Ulti-
mately the archegonium is burst irregularly by the enlarging sporogonium, and the
spores are set free by the removal of a circular lid at the summit.

In Sphagnum a true seta is not developed, the region between foot and capsule
remaining quite short. The same result, however, is achieved by a considerable

BRYOPHYTA. 701

elongation of the axis of the female shoot taking place in the region immediately
below the group of archegonia. The capsule is thus hoisted up on a long stalk,
though this stalk is no part of the sporogonium (cf. fig. 897 }),

The remains of the Bog-mosses form an important constituent of peat.

Andreceacee.—A small family, including the single genus, Andrewa. They are
amongst the first settlers upon new and inhospitable rock-surfaces, and play an
important part as soil-formers (cf. vol. i. p. 266). In them the mode of bursting of
the spore-capsule is altogether peculiar amongst Mosses. Four longitudinal slits

Fig. 398.—Mosses.

1A germinating spore. 2 A Moss-protonema. % Protonema giving rise to a bud from which will arise a leafy moss-shoot.
4 Longitudinal section of the tip of a male shoot of a Moss; small, club-shaped antheridia are present between the scales:
5 Tip of a female shoot with archegonia; two of them containing sporogoniums have enlarged, and in the left-hand one
of these two the upper part of the archegonium (calyptra) has been torn from the basal portion. 6 Leafy female
shoot bearing a fully developed sporogonium; the calyptra is still in position. 1,2, 8 x 350-400; 4x 15; 5 x 80; 6x 5.

arise in its wall, and the four valves remain attached to one another at the apex
(ef. fig. 397 3°). :

Bryacew.—This family includes the vast majority of the Mosses. The germinat-
ing spore produces a simple, branching, filamentous protonema (figs. 398+ and 398 7)
on the surface of the ground, certain of its branches developing as colourless
rhizoids and penetrating the substratum. From the protonema the ordinary leafy
Moss-plant arises as a lateral bud (cf. fig. 398%). The curious properties of the
protonema of the Luminous Moss (Schistostega osmundacea) have been already
described (cf. vol. i. p. 385, and Pl. I. fig. p). The leafy shoots become rooted by the
development of rhizoids from their lower extremities, and bear their leaves, as a
rule, in three rows, though a slight twisting of the stem often disguises this fact.

702 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

The Luminous Moss just mentioned is an exception; in it the leaves are arranged in
two rows (ef. fig. 399°). The leaves of Mosses are generally simple, and (unlike the
Jungermanniaceee) provided with midribs. In many of the Polytrichee, and in
Barbula aloides, &c. (cf. fig. 3957), the upper surface of the leaf bears longitudinal
ridges of thin-walled chlorophyll-containing cells, thus adding to its assimilating and
transpiring surface. The Moss-plant can propagate freely by means of brood-bodies
and gemme. These sometimes take the form of modified leaves, sometimes of little
stalked bodies on the leaves; occasionally they are collected together into little recep-
tacles at the tips of the shoots, as in Tetraphis (cf. fig. 196, p. 23, where this and other
cases are illustrated). The antheridia and archegonia are collected into little recep-
tacles or “flowers” placed either at the tips of the shoots (in the acrocarpous Mosses,
of. figs. 8971 and 398°), or laterally in the leaf-axils (in the pleurocarpous Mosses, cf.
fig. 3977"). Occasionally both antheridia and archegonia are present together in the
same “flower” (cf. fig. 397°), but more frequently they are in separate receptacles
(ef. figs. 398 * and 398°). Mingled with them are sterile scales, the paraphyses. The
structural details of the sexual organs and the mode of fertilization in Mosses has
already been described (ef. pp. 64-66). After fertilization the egg-cell within the
archegonium divides and enlarges, and gradually fashions itself into the sporogonium,
the asexual generation of the Moss. For a time the archegonium stretches with the
growing embryo, but sooner or later it is ruptured (ef. fig. 398°), and its upper
portion raised aloft on the sporogonium as the calyptra. Sometimes the calyptra
forms a closely-fitting cap, entirely investing the capsule as in Polytrichum (fig.
397°), or it may be a little hood split down one side as in Brywm (figs. 3976 and
398°). After the raising of the calyptra by the elongation of the stalk or seta of
the sporogonium the apex swells and develops into the capsule. Though in almost
all cases the sporogonium consists of a capsule borne on a long smooth stalk (the
seta), which is embedded below in the tissues of the female shoot of the Moss-plant,
a very considerable amount of variety is met with in the structural details of the
capsule itself. The seta may pass gradually into the capsule as in Brywm (fig.
397°), or there may be a bulb-like enlargement (apophysis) at the base of the
capsule as in Polytrichwm (fig. 397%), or this enlargement may attain considerable
dimensions, exceeding the spore-producing part of the capsule, as in Splachnum
(fig. 399). This apophysis is of importance as an assimilating and transpiring organ,
and it is the only portion of the whole Moss which bears stomata. Within the
capsule is the spore-layer. This has the form of a hollow cylinder surrounding a
central sterile tissue, the columella. External to the spore-layer, and between it and
the wall of the capsule, is a lacuna generally traversed by chlorophyll-containing
filaments of cells. Above the spore-layer the columella expands into a mass of
tissue, which forms the lid of the capsule (operculum, ef. figs. 397° and 3977). At
the periphery of the lid, where it abuts upon the wall of capsule, a ring of cells
becomes marked out (the annulus); later, by the rupture of this ring the lid comes
away, and the mouth of the capsule is guarded only by a set of teeth, the peristome
(of. figs. 397°, 397 °, 3993, and 3998), By the time that the lid is ready to come

BRYOPHYTA. 7038

away the spores are ripe, and the columella, &., have dried up and collapsed. The
teeth of the peristome are exceedingly varied in pattern in the various genera of
Mosses; typically there are two series of them forming an outer and an inner peri-
stome (cf. fig. 397°), but they are differently thickened, fused, and divided, and one
or even both series (e.g. Gymnostomum), may be absent. They are very hygro-
scopic, and their function will be alluded to later on when we are discussing the

Fig. 399.—Spore-capsules of Mosses.

1 Splachnum lutewm. 2 An unripe capsule of the same. % A ripe and open capsule of the same, 4 Splachnum vasculosum.
5 Longitudinal section of a ripe capsule of this moss, showing the large apophysis below containing lacune, and traversed
in the middle by the columella; above is the capsule proper with persistent columella, spore-sac, and peristome.
8 Splach pull ‘ 7 An unripe capsule. 8A ripe capsule of the same. 9 and 10 Schistostega osmund
11 A ripe capsule of the same, 1, 4, 6, 10 natural size; 2, 3 x 2; 7,8, 9x10; 11x15; 5 x 100.

distribution of spores. In the Polytrichee the peristome is not quite the same as in
other Mosses. In this group the teeth are very numerous and quite short, and from
their apices a membrane (the epiphragm) remains stretched after the fall of the lid
(ef. fig. 397 *). The spores here tumble out between the teeth.

The position of the sporogonium is of course determined by that of the female
“flowers”; where these are terminal the sporogonium will be terminal (acrocarpous),
similarly where lateral (pleurocarpous). The number of genera of Bryacez is so

704: THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

numerous that it is hardly possible to mention even the most notable here. Fontin-

alis is of interest in being aquatic; Splachnum (ef. fig. 399) in having a very large

apophysis and being saprophytic on animal excreta (cf. vol. i. p. 118). Buabawmia

aphylla is an exceedingly simple form and vegetates in the protonema-stage. Leafy

shoots are only formed in connection with sexual reproduction, and even then they

are very rudimentary. This plant has been thought to be a primitive type of Moss.
Fossil Mosses are met with in Tertiary and more recent deposits.

Class II.—PTERIDOPHYTA, Vascular Cryptogams.

As in the Bryophyta, so here, a well-marked alternation of generations is ex-
hibited in the life-history. Whilst in the Liverworts and Mosses the oophyte is the
dominant stage (“the plant”) here the sporophyte constitutes “the plant”. The
oophyte is a mere prothallium of simple nature, the sporophyte is a complex struc-
ture with root, stem, and leaves, and a well-marked vascular system. It becomes
free from the prothallium at an early stage in development. The Pteridophyte
contain the following alliances: Filices, Hydropterides, Equisetales, Lycopodiates.

The plant or sporophyte generation attains to a wide diversity of form in the
Pteridophytes; thus, amongst the Ferns the stem is often short and bears a rosette
of fronds, or is elongated and rhizome-like with leaves at intervals; in the Equiset-
ales it is erect and jointed, and the leaves are reduced to toothed sheaths; and in
many Lycopodiales the stem is procumbent, much-branched, and covered with
simple scale-like leaves over the entire surface. Upon the leaves are borne the
sporangia which contain the spores. The sporangia may be either scattered over
ordinary leaves or on special leaves collected into cones. There is one feature con-
nected with the spores that must be described here. Though in the Ferns and in
many other Pteridophytes all the spores are of one kind and each gives rise to a
prothallium bearing both archegonia and antheridia, there are Pteridophytes in the
alliances Hydropterides and Lycopodiales in which two sorts of spores are produced.
The latter are known as heterosporous, the former as homosporous. Where the
plants are heterosporous the spores are of two sizes, and the larger ones (macrospores)
are contained in fewer numbers in the sporangia than are the smaller ones (micro-
spores). On germination the macrospore gives rise to a female prothallium only,
the microspore to a male prothallium; i.e. growths which bear respectively arche-
gonia and antheridia. The male prothallium is a very simple structure, and its part
is played so soon as it has liberated its spermatozoids. The female prothallium
having to nourish the young sporophyte for a while, until such time as it can live
independently, is larger, and is usually well-provided with food-material.

Contrasting the Pteridophytes and Bryophytes, the Fern-plant corresponds to
the sporogonium of the latter and the prothallium to the Moss-plant or Liverwort
thallus. In the former the sporophyte, in the latter the oophyte generation is the
more complex. But that a Fern-plant has been elaborated out of a Moss-sporo-
gonium, or that the Fern-prothallium is a reduced or degraded Moss-plant, is exceed-

PTERIDOPHYTA, 705

ingly improbable. It is more likely that the two groups have had a common
origin, and have then developed along entirely different lines

Alliance XXII.—Filices, Ferns.

Families: Hymenophyllacew, Polypodiacee, Cyatheacew, Gleicheniacce, Schizwacerr,
Muarattiacee, Osmundacee, Ophioglossacece.

With us for the most part Ferns have short underground stems bearing a rosette
of leaves as in the Male Fern (Aspidiwm Filix-mas) and Hart’s-Tongue Fern (Scolo-
pendriwm vulgare), or there may be an elongated horizontal underground rhizome,
as the Bracken Fern (Pteris aquilina) and Polypody (Polypodiwm vulgare), the
leaves being produced at intervals. In the tropics and sub-tropical regions, on the
other hand, Tree Ferns are common. They belong mostly to the genera Cyathea,
Alsophila, and Dicksonia. In these a considerable caudex is developed (cf. fig. 347,
p. 478, and vol. i. p. 714), which is often enveloped in a perfect plexus of aérial
roots. Many Ferns are epiphytic, especially in tropical forests (e.g. Platycerium
alevcorne, fig. 349, p. 475); with us Polypodium vulgare is often met with envelop-
ing the trunks and boughs of large trees. The tropical genus Lygodium is charac-
terized by its climbing habit, the long rachis of its compound leaf twining like the
stem of a twining plant. The view has been held, and is alluded to on p. 12, that
the fronds of Ferns are not really leaves but modified stem-structures, the scaly
structures that occur on the stem and fronds being regarded as the true leaves. It
is sufficient to say that this view is not very widely held amongst Botanists, and
that here the term leaf is used as synonymous with frond. Broadly speaking, Ferns
love moist and shady habitats; they grow especially in woods and forests, and on
humid rocks beside streams, &c. Generally their leaves are thin and delicate, and
ill-adapted to withstand prolonged desiccation.

Borne on the leaves of Ferns are the sporangia, tiny capsules in which the spores
are developed. The form of the sporangium and the arrangement of these bodies
varies in the different families of Ferns—indeed the sporangia afford characters
which are used for the grouping and classification of Ferns. In the commonest
Ferns (belonging to the predominant family Polypodiacez) the sporangium resembles
two watch-glasses placed together, the rim being occupied by a series of large, thick-
walled cells (the annulus), and the whole mounted on a little stalk (cf fig. 400 ™).
In other families the stalk may be absent, the annulus incomplete, oblique, trans-
verse or altogether wanting, &., as will be pointed out in treating the several
families. The sporangia are aggregated into clusters, the sori, and these are in
many cases protected by little outgrowths of the leaf-surface (indusia) or under the
infolded margins of the leaf. The form and arrangement of the sori and indusia
provide the characters according to which the large family Polypodiacee is sub-
divided.

Hymenophyllacec.—The Filmy and Bristle Ferns. There is generally a

rhizome which bears delicate fronds at intervals (cf. fig. 4007); the lamina of the
Vou. IL. 95

706 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

leaf is often only one cell thick, and stomata occur only in the genus Lowsoma (New
Zealand). The other genera, Hymenophyllum (the Filmy Fern) and Trichomanes,
are both met with in Great Britain. The former is not uncommon on the rocks
beside waterfalls, but the latter (Trichomanes radicans, the Killarney Fern) seems
to be almost restricted to the south of Ireland. In this family the sporangia occur
at the margins of the fronds on the excurrent veins (see fig. 400°). They are
sessile, and the annulus is transverse, 7.¢. at right angles to the axis of the sporan-
gium. The sorus is surrounded by an enclosure formed from the leaf-margin; this
investment is cup-shaped in T'richomanes and bivalved in Hymenophyllum. Often
in the former genus the axis on which the sporangia is inserted projects considerably
from the cup—hence the name Bristle Fern. In this family the prothallium is
unlike that of other ferns, being frequently filamentous and branched; the filaments
often bear local expansions, upon which the archegonia are inserted.

There are about 200 species of Hymenophyllacex.

Polypodiacew.—By far the largest family of Ferns; indeed this family includes
more than three times as many species as all the rest of the Pteridophytes together.
Almost all our familiar European Ferns belong to it. ‘The character which they all
have in common is a stalked sporangium (fig. 400"), with vertical annulus. The
distribution and form of the sori are exceedingly various, The Polypodiaces have
been separated into the following tribes:—Pteridew, Aspidiew, Aspleniew, Daval-
liec, Polypodiew, Grammitidee, Acrostichew. In the Pteridec the sori occur at
the margin of the leaf; in the Bracken Fern (Pteris aquilina) the frond is much
branched, and the sori are everywhere continuous on the pinnule-margin; they are
covered in by an indusium derived from the margin; in the Maiden-hair Fern
(Adiantum Capillis-Veneris) the tip of the pinnule is folded back over the sorus.
In the Aspidiew the sori are scattered, circular, and covered in by a circular or
kidney-shaped indusium. Aspidiwm Filix-mas (the Male Fern) belongs to this tribe.
The sorus is much elongated and linear in the Aspleniew, and the indusium is
inserted on one side of it (e.g. Asplenium Ruta-muraria, figs. 401° and 4017).
The Lady Fern (Athyrium Filix-femina), Hard Fern (Blechnum), Hart’s-tongue
(Scolopendriwm), &c., are members of this tribe. In the Davalliew, which include
the large tropical genus Davallia, the sorus is near the margin, and inclosed in a
pocket-like indusium. In the Polypodiew the sori are circular and scattered over
the under surface of the frond. There is no indusium (see fig. 400°). The Gram-
mitidew resemble the last-named in the absence of an indusium. The sori usually
follow the veins, frequently forming very elegant reticulations on the under surface
of the leaf, as in the tropical genus Hemionitis. The Gold and Silver Ferns (Gym-
nogramme) belong to this tribe. In the Acrostichew the whole under surface is
covered with sporangia, and there is no indusium. Examples are, Rhipidopteris
(fig. 400 *), Platyceriwm (fig. 349, p. 475), and Acrostichum.

Nearly 3000 species of Polypodiaceae are known.

Cyatheacee.—This family includes the: Tree-ferns (fig. 347, p. 473). The
annulus of the sporangium is slightly oblique; it is only indifferently represented in

PTERIDOPHYTA, 707

Fig. 400.— Various Ferns.

1 Nephrolepis Dufi. 2% Trichomanes Lyalliit, 3% Sorus of the same fern, with cup-shaped investment seen in longitudinal
section. 4 Rhipidopteris peltata. 5 Polypodium serpens. §& Portion of frond of Gleichenia alpina. 7 Schizcea sistulosa.
8 Botrychium lanceolatum. 9% Under side of a fragment of the frond of Gleichenia alpina; above the sporangia are
concealed by a tuft of scales, below they are exposed. 1° and 11 Fertile pinnule of Cyathea elegans. 12 Longitudinal
section of a sorus of Cyathea. 18 Sporangium of Cyathea. 14 8porangium of Polypodium. 15 Sporangium of Schizea.
16 Under side of the prothallium of Asplenium. 1, 2, 4, 5, 6, 7, 8 natural size; 8, 9, 10, 11, 12, 18, 14, 15, 16 x 5-20.

708 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

fig. 400%, In Cyathea (figs. 4001011) the indusium is cup-like, and closed
until the spores are ripe. In Dicksonia the sorus is marginal, with bivalved indu-
sium; in Alsophila the sori are scattered, and the indusium absent or rudimentary;
in Hemitelia the indusium is scale-like, and situated on one side of the sorus. Of
Cyatheaceze about 200 species are known.

1

Fig. 401.—Life-history of a Fern.

1A Fern-prothallium seen from the under side. 2 An archegonium in longitudinal section. 8 An antheridium. 4 Escape of
spermatozoids from antheridium. 5 Young sporophyte with first leaf arising from the prothallium. 6 Complete sporo-
phyte of Asplenium Ruta-muraria. 7 Under surface of pinnule of same, showing linear sori and lateral indusia, § A
young prothallium arising from a spore; the spore is below. 6 natural size; 1 x 8; 2, 3,4 850; 5x6; 7x3; 8x 240,

Gleichentacee.—Mostly tropical forms. The sporangia have a transverse annu-
lus, and are collected into little sori of 3 or 4 sporangia, often very closely packed
(of. figs. 400%, and 400°). The frond usually forks repeatedly. There is only one
genus, Gileichenia, which has some 40 species.

Schizceacew.—The members of this family are also for the most part tropical.

PTERIDOPHYTA. 709

The sporangium is sessile, and the annulus is situated at the apex like a cap (cf. fig.
400%). In Schizca (fig. 4007) the fertile pinnules bear two rows of sporangia
partly sunk in little pockets; in the climbing fern Lygodiwm the leaflets bear little
fertile spikes at the margin, and the sporangia are sunk completely in little pockets,
one row on either side of the spike. In Aneimia the frond divides into two
portions—a green vegetative portion, and several fertile branches whose ultimate
ramifications are beset with naked sporangia. In habit Aneimia is not unlike a
Botrychium (cf. fig. 400°). Of Schizeaceae there are some 70 species.

Marattiacece.—Tropical Ferns, many of them attaining considerable dimensions.
The fronds are distinguished by possessing a pair of stipules at their base. The
sporangia are more bulky than in the families hitherto enumerated, and in Angio-
pteris are arranged in rows very close together, whilst in Marattia, Kaulfussia, &c.,
all the sporangia of each sorus are joined together into little button or bean-like
bodies. There is no distinct annulus, though a little cap of cells possibly represents
one. There are 25 existing species, but this family was much more abundant, than
it now is, in paleozoic times; their remains are abundant in the Coal Measures.

Osmundacece.—Here also the sporangium is destitute of annulus, and possesses
a little cap of cells in place of it. In Osmunda regalis, the Royal Fern, the upper
pinnules of the frond alone produce sporangia, but in such quantity that their whole
surface is covered with them; thus the tips stand out in marked contrast to the rest
of the frond (hence the name “Flowering Fern”). The other genus of the family,
Todea, resembles a Filmy Fern in the delicate texture of its leaves. There are only
11 species altogether.

Ophioglossacece.—A small family including the Adder’s-tongue (Ophioglosswm)
and Moonwort (Botrychwwm). The frond here divides into a sterile and a fertile
portion, the latter seeming to arise from the base of the former. In the Adder’s-
tongue the sterile portion is unlobed, and the fertile portion spicate, the sporangia
being sunk in its substance. In the Moonwort (ef fig. 400%) both parts are
branched, the fertile portion resembling a panicle. The prothallium in this family
is a little subterranean tuberous body. The origin from it of the sporophyte
generation has not followed in any instance. There are twelve species of Ophio-
glossacez.

Alliance XXIII.—Hydropterides, Rhizocarps.

This alliance is nearly associated with the Filices and more particularly with the
earlier rather than with the last-mentioned families of that alliance. All the genera
are more or less aquatic in habit; but their distinctive feature is the fact that they
are heterosporous, i.e. that some sporangia contain macrospores (one in each
sporangium) the others microspores. The sporangia are collected into sori, which
are inclosed by metamorphosed leaf-segments into little fruit-like bodies.

Families: Salviniacew, Marsiliacew.

All the members of the alliance agree in their aquatic habit and in being hetero-
sporous. The macrosporangia are larger than the microsporangia, and contain one

710 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

big oval macrospore; the microspores are produced in numbers in the microspor-
angia. The macrospore, in addition to a hard wall, possesses an external gelatinons
layer with stratified structure. On germination, the macrospore develops its
(female) prothallium at one end, and, on the bursting of the spore-wall at the apex,
this prothallium and the archegonia developed on its surface, are exposed. Of the
contents of the spore, only a portion forms the prothallium, the rest remaining as a
reserve mass. The microspores, which are usually embedded in mucilage, undergo
several divisions (forming antheridia), and liberate spermatozoids, which fertilize

Fig. 402.—Hydropterides.

1 Salvinia natans, showing the floating and submerged leaves. 2 A portion of the same seen from the side, and showing the
sporocarps at the base of the submerged leaves. 3 A section through two sporocarps of Salvinia natans; that to the left
contains macrosporangia only, that to the right microsporangia. * Pilularia globulifera; one or two sporocarps are
shown at the base of the needle-like leaves. 5 Marsilia quadrifolia, showing sporocarps. % x 4; the rest, natural size.
(After Luerssen.)

the archegonia. From one of the archegonia the young sporophyte arises, and
gradually develops into the adult form.

Salviniaceee—Include two genera, Salvinia and Azolla, both of which are
floating plants. The former occurs in Southern Europe, the latter, though hardy
in Europe, is a native of America, Australia, &. Salvinia (figs. 4021 and 402)
has a stem which lies horizontally on the water, and develops both floating and
submerged leaves. The latter divide into numerous filaments, which hang down
like tassels in the water (cf. fig. 402%). They are the absorptive organs of the
plant, and play the part of roots. True roots, however, are wanting, even from the
embryo. The sporangia are borne on these submerged leaves close to the point
of attachment to the horizontal stem, generally in three groups or sori, each of
which is inclosed in a cup-like upgrowth arising from the submerged leaf (ef. fig.

PTERIDOPHYTA, . 711

402°). The arrangement of the sori is not unlike those in Trichomanes (ef. fig.
400%), except that the cup is closed round the sorus. In each sorus occur only
macrosporangia or microsporangia; but in each group of three sori usually one is
different from the other two. Each sorus with its investment constitutes a sporo-
carp. The other genus, Azolla, resembles a floating, leafy Jungermannia (cf. fig.
3967, p. 698); it is closely set with tiny leaves, and numerous true roots hang down
into the water. The macrospores are provided with a floating apparatus and hooks;
and the microspores which escape from their sporangia in packets have long barbed
appendages, which become attached to the hooks of the macrospores. Thus the
spermatozoids escape in the immediate neighbourhood of the female prothallia.

There are 9 species of Salviniacezx.

Fossil residues occur in the tertiary formations.

Marsiliacece—Containing the two genera, Pilularia and Marsilia. Both grow
in marshy or inundated ground, and spread their rhizomes horizontally, attaching
them by means of roots. The leaves in Pilularia (fig. 4024) are needle-like, and
each bears at the base a very short branch which develops into a sporocarp. In
Marsilia (fig. 402°) the leaves resemble those of Oxalis; near the base they give off
a branch which may bear several bean-like sporocarps. The sporocarps in both
these plants do not—as in the Salviniacezee—consist of mere sori with an investment;
but each is a leaf-segment in which a number of cavities develop (four in Pilularia,
many in Marsilia), cavities which ultimately are quite cut off from the exterior,
though they arise at first as pittings of the surface. In these cavities groups of
sporangia arise—both macro- and microsporangia in each chamber. The sporocarp
in this family is, therefore, in nature a leaf-lobe containing numbers of sporangial
cavities, and of much greater complexity than in the Salviniacee. The sporocarps
ultimately dehisce, the spores develop their prothallia, and fertilization takes place.
There are 32 species of Marsilia and 3 of Pilularia. P. Globulifera alone is
British. Fossils are found in tertiary formations.

Alliance XXIV.—Equisetales, Horsetails.

Possess jointed stems and small leaves inserted in whorls. The sporangia are
produced on special leaves arranged in cones. All living examples are homosporous,
but paleeozoic forms include heterosporous genera.

Families: Equisetacew, Calamarie.

The Equisetacew alone are represented by living plants, and include the solitary
genus Equisetwm, with about 40 species.

The habit of growth of the Equisetums is exceedingly characteristic. There is
a branching underground rhizome from which erect aérial shoots are produced each
year. From the nodes of the underground stems numerous fine roots arise (fig.
4032). The whole of the aérial shoot is green and assimilating, and the leaves are
represented by funnel-shaped sheaths bearing teeth inserted at the nodes. The inter-
nodes are ribbed and the whole structure harsh to the touch, and often brittle owing

712 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

to the large amount of silica contained in the epidermal mnprabrante. Tis early
spring shoots of many species are unbranched and terminate in spore-bearing cones
(eg. E. arvense, fig. 403%), whilst later on other branching shoots arise which me
sterile (fig. 4031). In other cases the fertile shoots are also branched (fig. 403”).

Fig. 403.—Equisetacez.

1Summer sterile shoot of Equisetum arvense. 2 Vernal, spore-bearing shoot of Equisetum arvense. 8% Fertile cone of
the same. 4A single sporangiferous scale (sporangiophore) of the same. 5 and 6 Spores with ‘‘elaters” expanded and
coiled. 7% Equisetum sylvaticum with cone. ® Prothallium of a Horse-tail with antheridia. 1, 2, 7 natural size; 8 x 3;
4x 6; 5,6 x 25; 8 x 30.

The branches arise from the main axis in whorls at the base of the leaf-sheaths,
and in most cases perforate the latter as they develop (fig. 4037). They repeat the
structure of the main axis, save that they are smaller and have fewer teeth to their
leaf-sheaths. E. maximum, common in this country in damp places, attains a
height of two metres, and is the largest British representative of the group, but

PTERIDOPHYTA. 713

£. gigantewm (Tropical America) is stated to reach as much as ten metres. The
Dutch Rush (2. hiemale) is largely used for polishing owing to the quantities of
silica it contains. Characteristic of the stems of Equisetums is the large central
air-space, which is only interrupted by diaphragms at the joints. Other spaces also
occur associated with the vascular bundles and in the cortex, alternating with the
bundles.

The spore-bearing cones (figs. 4032 57) consist of stalked, shield-like leaves borne
on the club-shaped termination of the axis. The scales bear numerous sporangia on
their under surface (fig. 403 +), and in these are the curious and characteristic spores.
The wall of the spore is three-layered, and the outmost layer splits away from the
one below it, forming four arms attached to the spore at one point (fig. 403°),
These arms, termed elaters (not to be confused with the elaters of Liverworts, cf.
p. 696) are extremely hygroscopic, and though at first coiled around the spores
(fig. 403°) become extended as the spores dry, and as their humidity fluctuates
contract and expand again. In this way the spores become entangled with one
another and are distributed in groups, arm-in-arm. The importance of this circum-
stance appears to be as follows:—The spores, though all of one sort (i.e. homosporous),
give rise to dicecious prothallia as a rule (of. fig. 4038, representing a male pro-
thallium ); consequently it is of advantage for promoting fertilization that a number
of prothallia should arise in the same neighbourhood. ‘This result is achieved by a
linking of the spores. The prothallia are richly lobed, but not unlike those of Ferns.

The Calamaric are found as common fossil remains in the carboniferous forma-
tions. They include casts of the medullary cavity, impressions of the surface, and
actual portions of the stems and cones in a petrified state. Many members of this
family attained gigantic proportions, and their stems underwent a well-marked
secondary increase in thickness. An examination of the cones shows that these
former Equisetales possessed both micro- and macrospores.

Alliance XX V.—Lycopodiales, Club-mosses.

Forms usually with elongated, branching stems and small leaves distributed over
them. The sporangia are borne on the upper surface of the leaf or in the leaf-axil;
the fertile leaves are in many cases aggregated into cones. Both homosporous and
heterosporous families occur.

Families: Lycopodiacece, Psilotacece, Selaginellacee, Lepidodendracece, Sigilla-
riacece, Isoétucec.

Whilst in the Filices and Equisetales several or many sporangia are present on
the fertile leaves, in this alliance there is only one, and this is situated on the upper
surface or in the leaf-axil. The sporangia in this group differ from those in many
of the Filices (e.g. Polypodiaceze) in being more massive and in having origin not
from single epidermal cells, but from a row or group. Their form also is in many
cases peculiar. The Lycopodiacez and Psilotaceze are homosporous, the other families
heterosporous. In the former the prothallia generally resemble those of Ferns, in

714 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

the latter their condition parallels that of the Hydropterides. Lepidodendracese
and Sigillariacee are represented by fossil forms only.

Lycopodiacece.—The Club-mosses proper include some 100 species, distributed
over various parts of the globe. The habit of a typical Lycopodiwm is indicated in
the accompanying figure of L. annotinum, with its branching stem closely set with
simple, scale-like leaves and terminal cones. The species common in mountain
regions in this country are L. clavatum, L. alpinum, and L. Selago; L. annotinum

——————

Fig, 404.—Lycopodium annotinum.

(fig. 404) is also met with. Of these L. Selago alone is devoid of cones, its sporangia
occurring on the ordinary leaves. The sporangium is generally large and kidney-
shaped, and is attached to the base of the upper side of the leaf (fig. 405‘); its
concavity is directed towards the axil of the leaf. Till recently the life-history of
Lycopodium was unknown, as difficulty was experienced in causing the spores to
germinate. It was first observed in certain tropical species, LZ. cernuum and others.
In this species the prothallium has the form of a tiny tuberous body, with a lobed
fringe on which the antheridia and archegonia are developed. The history of
development of the sporophyte from the egg has been followed and is of some
interest. In L. cernwwm the young plant consists of a tubercle bearing a tuft of

PTERIDOPHYTA, 715

leaves above. Gradually the stem elongates and the adult form is assumed. The
special interest attaching to this stage is that it is characteristic of the mature
Phylloglossum referred to below. It has been suggested that the last-named genus
is a primitive form which retains as adult character what is but embryonic in
Lycopodium.

The genus Phylloglosswm (found in parts of Australia and New Zealand) possesses,
in addition to its tubercle and tuft of leaves, a stalk which terminates in a cone of
sporangium-bearing leaves, There is only a single species.

Psilotacee—Includes two genera, Psilotum and Tmesipteris. Psilotwm is tropical;
it has delicate, angular, forking stems, and its leaves are reduced to tiny scales. It
is rootless and grows epiphytically. Its sporangia are three-chambered and are
borne on reduced leaves. Vegetative bulbils are frequently met with, especially on
those shoots which grow upon the substratum. Zmesipteris is also an epiphyte
(New Zealand and Australia). It has conspicuous, pointed leaves and long, trailing
stems. The ordinary leaves are simple, but the fertile ones fork like a V, and the
sporangium (which is two-chambered) is inserted on the upper surface at the junction
of the V. The prothallial stage is not known in either of these genera.

Selaginellacee.—A family of some 300 to 400 species, which are in large part
tropical, and all belong to the genus Selaginella. The shoots are forked and are
dorsiventrally flattened. The leaves are borne in four rows—two rows of smaller
overlapping leaves right and left of the median dorsal line, and two rather larger
ones along the edges of the stem (ef. fig. 1111, vol. i. p. 421). A very common
species in the alpine regions of Europe is Selaginella helvetica, whilst S. selaginoides
(=S. spinosa) is British. The last-named species, unlike the majority of Selaginellas,
is not flattened, and its leaves are distributed around the stem as in a Lycopodium.
A characteristic feature is the presence of a little tongue inserted in the median line
of the upper surface of the leaf near its point of insertion; this is known as the
ligule. The roots in most cases arise, not directly from the stem, but from special
branches termed rhizophores. Selaginella is heterosporous. The sporangia are
spherical and arise in the axils of the fertile leaves, which are collected into cones.
The macrosporangia contain four macrospores, and the microsporangia numerous
microspores. Both kinds of sporangia occur usually in one cone, the former below;
or they may be in rows along the sides of the cones; or, finally, the two sorts of
sporangia may be on different cones.

The product of germination of a microspore consists of a single, simple anther-
idium, containing spermatozoids, which are provided with two flagella attached to
the pointed end. The macrospore produces a small, green female prothallium at
one end (as in the Hydropteridex, p. 710), whilst the rest of the spore, which here
divides into large cells, serves as a reserve of food-material. The green portion
bears the archegonia, and is exposed. After fertilization, an embryo arises, and
gradually develops into the Selaginella-plant. The embryogeny presents various
features of interest. In particular may be mentioned the production of a suspensor
from that portion of the embryo which is towards the neck of the archegonium.

716 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

By the elongation of this suspensor the embryo proper is brought down into the
aforementioned food-reserve, where it continues its development. This process is
quite similar to the corresponding stage in Flowering Plants, where the suspensor
is almost universally found.

Lepidodendracee.—This family, represented only by fossils from the Devonian
and Carboniferous formations, consisted of large-growing Lycopod-like forms, with
huge stems clad with linear leaves. They exhibit a secondary growth in thickness
(wanting in recent Lycopods), and both micro- and macrospores were produced. in
the cones, Casts of Lepidodendron-stems bear characteristic rhomboidal areas
corresponding to the leaf bases, and upon these the actual leaf-scars may be seen.

Fig. 405.—Lycopodiales.

1 Isoétes lacustris. 2% Expanded base of leaf showing the sporangium immersed in its socket and partly hidden by the velum
and the ligule above. 8 Longitudinal section of base of leaf showing the strands crossing the sporangium and the inser-
tion of the ligule. 4 Leaf from the cone of Lycopodium clavatum showing the kidney-shaped sporangium. 5 A single
spore of L. clavatum. 6 Prothallium of L. annotinum with young plant attached. 1 natural size; 2, 3, 4,6x 10; 5 x 100.
(After Luerssen.) eae ,

Sigillariacee.—Another family which flourished in carboniferous times. Like
the Lepidodendracex, their stems are gigantic, thickened and scarred; they were
also heterosporous. The marks on the stems are not rhomboidal, but shield-like,
and they stand in vertical rows. The curious branching remains named Stigmaria
constitute the root (or rhizome) of Sigillaria.

Isoétacece.—Is a small family of aquatic mode of life, containing the single genus
Isoétes, which is represented by some 50 species in various portions of the globe.
Unlike the other members of the alliance Lycopodiales, Isoétes possesses an ab-
breviated stem, bearing a tuft of lance-like leaves. The common British species
Isoétes lacustris may serve as type of the genus (fig. 4051). It grows in quantity
in the mud at the bottom of upland tarns and lakes in the northern parts of the
country, and is attached by delicate roots which repeatedly fork. The very short

PHANEROGAMIA. 717

stem is furrowed on two sides, and from these furrows arise the roots. On rare
occasions it is branched. From this stem arise numerous pointed leaves, which
are slightly expanded below. Each leaf bears a sporangium, immersed in a socket
on its upper surface (fig. 405°), and partly covering the sporangium a membrane,
the velum. Immediately above the sporangium is the ligule, a little tongue-like
emergence of unknown function (figs. 405? and 405°), Macrosporangia, containing
several large macrospores, are generally found on the outer leaves, and micro-
sporangia, with very numerous microspores, on the inner ones, The sporangia are
crossed by strands of cells (cf. fig. 405%), termed trabecule, but these do not
partition them into chambers. The germination of the spores presents certain
resemblances to the same event in Selaginella, but it cannot be followed out in
detail here.

An interesting feature in the structure of Iscétes is the existence of a cambium-
like zone in the stem just outside the central bundle-cylinder. This adds new tissue,
both towards the inside and outside, but most abundantly towards the outside.
This latter secondary cortex is parenchymatous, but in time it becomes corky.
To its formation is due the curious form of the stem.

Though many species of Isoétes live below water, others are terrestrial or
semi-aquatic in habit. J. lacustris, as it grows at the bottom of a mountain tarn,
is very similar in general appearance to two flowering-plants which affect the same
situation, viz., Lobelia Dortmanni and Littorella lacustris; a closer inspection,
however, will readily distinguish it.

Phylum IV.—PHANEROGAMIA, Flowering Plants

The general characters of Flowering Plants have been so fully dealt with in
previous sections of this work that little more is needful here beyond a bare outline
of the classification of their divisions and alliances.

The Phanerogamia are characterized by the production of seeds. The macro-
sporangia of heterosporous Archegoniate are here represented by ovules, the macro-
spores by embryo-sacs, and the microspores by pollen-grains. The macrospore
(embryo-sac) remains inside its sporangium (ovule), and here produces the reduced
female prothallium (endosperm), which never has an independent existence. An
egg-cell is formed within the embryo-sac, and this is fertilized by the pollen-tube
which has arisen from a pollen-grain lodged upon a suitable receptive surface in
the vicinity of the ovule. Ultimately, after the embryo has attained a certain
differentiation, the whole macrosporangium, with contained embryo and food-
material, comes away, and is known as the seed.

The oophyte or prothallial generation is thus suppressed as an independent stage
in the life-cycle. The sporophyte, on the other hand, attains to a markedly more
complex development than in the groups already treated. Fertilization of archegonia
on free-growing prothallia by swimming spermatozoids is here replaced by a direct
penetration of pollen-tubes to the ovules. To the “flower” also new duties are

718 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

allotted. In the Pteridophytes, fertile “cones” are frequently met with. They are
assemblages of leaves bearing sporangia, and with the shedding of the spores
accomplish their function. But in the Phanerogams it is not so. The stamens,
having shed their pollen-grains (microspores), truly are done with. But the carpels
which bear the ovules persist in situ until the ripening of the seed. And in the
vast majority of Phanerogams, structures accessory to the stamens and carpels have
become associated with the flower. These, forming the perianth, promote the
transfer of pollen by attracting insects to the flowers in the innumerable ways
already fully indicated in this volume. A minority of species depend on wind, and
are destitute of attractive perianths. It is worthy of passing notice that wind-
pollinated plants, though relatively few in species, are well represented in number
of individuals in the various Floras of the globe. It is sufficient to instance the
Conifers, Grasses and Sedges, Palms, Amentacex, and Urticacez.

The phylum Phanerogamia is divided into two sub-phyla, Gymnosperme and
Angiosperme, which differ technically in that in the former the ovules are exposed
on scales and receive the pollen-grains direct into the micropyle, whilst in the latter
the ovules are borne in closed chambers, the ovaries, and the pollen is received on a
special organ, the stigma

Sub-phylum A.—GYMNOSPERM 2.

The pollen is received direct upon the nucellus of the ovule, whence the pollen-
tube penetrates to the egg-cell. The embryo-sac (macrospore) is filled with the
endosperm (prothallium) which bears archegonia sunk in its substance at. that end
which is directed towards the micropyle. In almost all cases the archegonia possess -
neck- and canal-cells in addition to the egg.

The phenomena accompanying fertilization and seed-production in the Gymno-
sperma having been described at pp. 418 and 437, brief statements of the general
external characters alone are given below.

The Gymnosperme are divided into 3 Classes: Cycadales, Coniferse, Gnetales.

Class 1—CYCADALES, Cycads,

Alliance XXVI.

Family: Cycadacec.

In habit the Cycads generally resemble the Tree-Ferns and Palms, They possess
for the most part unbranched columnar stems terminating in a crown of large pin-
nate leaves. The surface of the stem is scarred with the bases of the fallen leaves,
and recalls in appearance that of the fossil Lepidodendrons (cf. p. 716). In height
Cycads do not exceed about 12 metres, and usually they do not attain even these
dimensions. The flowers take the form of cones of closely aggregated scales, which
vary in number from 80 to 600. The cones are respectively male and female, and

GYMNOSPERM A. 719

(From a photograph.)

Fig. 406.—A group of Cycas revoluta.

720 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

are produced in close proximity to the apex of the plant, and sometimes (as in the
female cone of Cycas) are actually terminal in position. The scales (stamens) of
the male cones are usually boat- or shield-shaped, and bear very numerous pollen-
sacs on their under surfaces, often aggregated into little groups or sori. The female
cones are generally more massive than the male, and their scales (carpels) are shield-
like or seale-like in form. In Cycas revoluta (ef. fig. 2087, p. 74) the carpels more
nearly resemble the foliage-leaves, and the ovules are borne in the position of
leaflets. In other genera the number of ovules is restricted to two. Pollination is
accomplished by the wind, and the ovule as it ripens develops a hard shell enveloped
in a fleshy coat. The seed thus exhibits the superficial characters of a drupe (ef.
p. 428).

Cycads are restricted to the warmer regions of the globe, and are especially
characteristic of the Floras of Australia (Macrozamia, Bowenia, Cycas) and Central
America (Zamia, Ceratozamia, Dioon). There are nearly 80 species, belonging to
9 genera, and they have mostly a somewhat restricted distribution. Fossil remains,
from the Cretaceous onwards, are abundant, and show that in former times the
Cycads formed a much more important constituent of the vegetation than at the
present day.

A living collection of these interesting plants is cultivated in the Palm-house in
Kew Gardens; it is exceedingly rich in forms, all the genera, and a large number of
the species being represented.

Class II.—CONIFER &.
Alliance X XVII.

Families: Araucariacece, Abietinece, Taxodier, Cupressinew, Taxacece.

The Coniferze, which include the various Pines, Firs, Junipers, Cypresses, and
Yews, have characteristically branched stems. The leaves are usually linear and
needle-like or scaly, rarely possessing an expanded lamina. The flowers are
unisexual, and occasionally the sexes are on different individuals. In by far the
larger number of Conifers the flowers are cone-like, i.e. aggregates of scales set
upon a central axis and bearing respectively ovules and pollen-sacs. The stems of
Conifers thicken up in the manner characteristic of Dicotyledons, but the secondary
wood is composed entirely of tracheides (fibre-shaped elements), with peculiar
bordered pits (¢f. vol. i. figs. 10%%* p, 45); vessels are absent from it. In a great
number of forms resin-ducts are present.

The families above given fall into two groups. The first of these includes the
Araucariacexs, Abietines, Taxodies, and Cupressines, and is characterized by the
female flowers being cone-like. In the Taxacez, on the other hand, the female
flowers are rarely in cones.

Araucariacee.—This group is familiar to everyone in the widely cultivated
Chili Pine or “Monkey-puzzle” (Araucaria imbricata). The cones are made up
of scales spirally arranged, and the ovules are solitary on the scales of the female

GYMNOSPERM A. 721

cones. The only other genus is Agathis (Dammara). These two genera include
14 species, distributed in the Southern Hemisphere only.

Abietinew.—This family includes the majority of familiar Conifers of the
Northern Hemisphere. They are distinguished by the fact that the scales of the
female cones are divided into an upper ovule-bearing scale (the ovuliferous scale)
and a lower subtending bract scale. The ovules are borne in pairs on the former,

itt

)

=

Fig. 407,—Female Cone and Scales in Abietinez.

1 Cone of the Silver Fir (Abies pectinata). *% Bract scale and ovuliferous scale of the same seen from the outside (the bract
scale is pointed). % Ovuliferous scale of same seen from above, showing the two winged seeds, and the bract scale behind.
4 Longitudinal section of bract and ovuliferous scales, showing a seed in situ upon the latter. 5 A winged seed of the
same. 6 Longitudinal section of the seed. 7’ Ovuliferous scale of the Scotch Pine (Pinus sylvestris) seen from above; it
bears two ovules. § Single ovuliferous scale of Larch (Larix europea) showing two ovules on its surface and bract scale
- (with bristle) below it. 9 Longitudinal section of the ovuliferous scale of the Larch. 1 nat. size; the other figs. enlarged.

and on ripening into seeds are provided with membraneous wings in most cases.
The relations of the parts of the scales and of the ovules are fully illustrated in
the accompanying fig. 407. The pollen-grains also are characteristic, being in
nearly all cases provided with two sac-like appendages which promote transit by
wind (cf. fig. 217 8, p. 98).

Included here are the Pine (Pinus), Cedar (Cedrus), Larch (Larix), and the

Vou. II. 96

722 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

various kinds of Firs (Abies and Picea). All have needle leaves, but variously
arranged. In Pinus the needles are borne in tufts of two (figs. 4084 and 408°) or
three or five. The tufts are really short branches which arise in the axils of relatively

Fig. 408.—Mountain Pine (Pinus Pumilio).

1 A single polliniferous scale (stamen) seen from above. 2% Three polliniferous scales, one above the other, seen from the side.
The pollen falling from each anther alights on the upper surface of the stamen next below. % Two spikes of polliniferous
scales. 4 Branch with apical group of staminal fiowers from which pollen is being discharged. 5Female flower. 1,2 x10:
3x8; 5x2; 4 natural size,

inconspicuous scales (cf. fig. 408°) and though these branches are produced plenti-
fully, permanent long branches arise only at the yearly limits of growth. The

GYMNOSPERM A. 723

Fig. 409.—The Scotch Pine (Pinus sylvestris).

724 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Fig. 410.—The Arolla Pine (Pinus Cembra).

GYMNOSPERMA, 725.

Pines may conveniently be divided into 2- and 3-leaved forms on the one hand, and
5-leaved on the other. The former agree in possessing cones of the type shown in
fig. 337°, p. 448, in which the ends of the ovuliferous seales visible at the surface
of the cone are pyramidal, whilst the 5-leaved forms are without these terminal
pyramids, Among the 2-leaved Pines (20 Species) are included the Scotch Pine
(P. sylvestris, fig. 409), the Stone Pine (P. Pinea), the Mountain Pine (P. humilis
or montana, Plate X., and fig. 135, vol. i. p. 549), the Corsican and Aleppo or Shore
Pines (P. Laricio and P. halepensis), and many others. Of the 16 species of 3-
leaved Pines the majority are North American and Oriental. The Himalayan
P. longifolia has needles nearly half a metre long, and the Californian P. Coulteri
cones attaining a like length.

The 5-leaved forms include about 35 species, of which the beautiful Arolla Pine
(P. Cembra, fig. 410) is a European, and the Weymouth Pine (P. Strobus) a North
American example.

The genus Cedrus is represented by 3 forms, the Cedar of Lebanon (C. Libani),
common in Asia Minor, the Deodar (C. Deodara) of the Himalayas, and the Atlas
Cedar (C. atlantica). Some authorities regard these as but varieties of one species.

The Larch (Laria, ef. fig. 33871, p. 448, and fig. 354, p. 483) bears its needles,
which are deciduous, in tufts. The Firs which comprise the genera Abies, Picea,
and Tsuga, differ from the Pines, &., in that the leaves are borne directly upon
the elongating branches. Abies, typified by the Silver Fir (Abies pectinata, cf.
fig. 177, vol. i. p. 717), has erect cones (cf. fig. 4071, p. 721), with conspicuous bract
and ovuliferous scales; on ripening, the scales disarticulate from the axis of the cone.
Picea, typified by the Spruce Fir (Abies eacelsa, ef. fig. 105, vol. i. p. 415), has.
pendulous cones, with persistent scales, and, as a rule, the bract scale remains
relatively short. Tsuga Douglasir, the Douglas Fir, and the Hemlock Firs are in
certain respects intermediate between the Silver and Spruce Firs.

In all there are 120 species of Abietineze distributed over the cooler parts of
the Northern Hemisphere.

Taxodiece.—Are characterized by bearing more than two ovules on the scales of
their cones. They include the two big Sequota-species of North America, 8S.
gigantea, the Wellingtonia or Californian Mammoth Tree, and S. sempervirens, the
Red-wood, both of which attain to huge dimensions. Taxodiwm distichum, the
so-called Deciduous Cypress, interesting on account of the curious knee-like roots
which it produces above ground, Oryptomeria japonica, and Sciadopithys verti-
cillata, the Umbrella Pine of Japan, all cultivated in this country as ornamental
trees, are members of this group, which comprehends some 12 species in all.

Cupressinece.—Are characterized by the fact that their cones have their scales
in whorls, not spirals (cf. figs. 336° and 3367 on p. 442, and figs. 33734 p. 443).
They include about 80 species, amongst them the Cypress (Cupressus), Arbor Vite
(Thuja), Juniperus, and other ornamental genera.

Taxacece.—Have generally few scales in their female cones, and sometimes, as in
Taxus, the Yew (cf. fig. 234, p. 145, and figs. 336152345 p, 442), the ovule is

726 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

terminal on a little shoot of its own. The seeds in this group are frequently
embedded in a fleshy investment (often arillar in nature). Besides the Yews, there
are included several peculiar Australasian forms, and the Maidenhair Tree, Gingko
biloba (ef. fig. 3377, p. 443). There are about 70 species of Taxacee.

Class III.—_GNETALES.
Alliance XXVIII.

Family: Gnetacee.

This family which includes three very dissimilar genera, Hphedra, Gnetwm, and
Welwitschia, is by no means easy to define. In habit they are all of them quite
unlike the members of the two preceding classes, but yet they fall under the sub-
phylum Gymnosperme in view of the fact that the pollen-grain has direct access
to the nucellus of the ovule and from the resemblance (rather remote) which their
ovules and embryogeny presents to other Gymnosperms. They agree amongst them-
selves in possessing flowers with perianths, vessels in their wood, and in the absence
of resin-ducts from their tissues.

Ephedra is a good example of a switch-plant, having jointed assimilating shoots
with little scale-like leaves at the nodes, as in Casuarina or Equisetum. The
flowers which are borne in little clusters, are small and unisexual. The male flower
consists of a central columnar stamen bearing 2-8 anthers and inclosed in a 2-leaved
perianth. The female flower has an ovule with one integument and a little
perianth. As the seed ripens the bracts around the flower become red and fleshy.
There are some 20 species scattered over the warmer regions of the globe, including
the Himalayas, Mediterranean, and Mexico.

Gnetwm occurs as a liane or erect tree, and has expanded leaves like a Dicoty-
ledon, in decussating pairs. The flowers occur in clustered, catkin-like spikes, on
which they are arranged in whorls. The male flowers are very like those of
Ephedra, the female have a central ovule with 2 integuments inclosed in a flask-
shaped perianth. On ripening, the perianth becomes fleshy, and the outer integu-
ment of the ovule hardens to a stone. There are 15 species, distributed in the
tropics.

Welwitschia mirabilis is a plant altogether unique. Discovered some thirty-
five years ago by the botanical explorer Welwitsch, it has formed the subject of a
classical monograph by Hooker. It occurs in the desert regions of West Tropical
Africa (Angola, Damaraland, &.). The stem is dwarf and top-shaped (cf. fig. 411),
and may attain more than a metre in diameter. The summit of the plant never
reaches far above the surface, and it bears two huge leathery leaves which sprawl
on the sand on either hand. Actually 4 leaves are produced, the 2 cotyledons,
which fall away whilst the plant is still quite young, and an additional pair placed
at right angles to the cotyledons and persisting throughout the life of the plant.
These 2 leaves grow continually at the base whilst their apical regions become

GYMNOSPERM A, 727

14 NN HG

Fig. 411.— Welwitschia mirabilis in its natural surroundings (from a sketch by its discoverer),

ih

i IN i
be a

He
fc i

SASS
——-
Se

YS

as

Tod

Us

728 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

tattered and broken. Welwitschia, once established, does not increase much in
length but continually in thickness. From the edge of its disc, in the leaf-axils,
arise branches which bear cones (cf. fig. 411). The male cones are small, and in the
axils of their scales occur flowers consisting of 6 stamens united together into a
sheath and surrounding a central structure which resembles an ovary, and contains
a single ovule, which is, however, so far as is known, always abortive. This ovary-
like structure is provided with a trumpet-like “stigma”, and the occurrence of this
remarkable structure in the male flowers points to the fact that the ancestors of
this plant possessed hermaphrodite flowers. The fertile female flowers occur in the
axils of the scales of other much larger cones, which become bright red in colour.
Each flower consists of a perianth containing an ovule with 2 integuments, but
although the imner of these integuments is very long, there is no stigma-like
structure as in the male flower, and the pollen-grain reaches the nucellus. The
developmental history of the ovule and embryo is exceedingly peculiar—as it is also
in Gnetum—but we cannot enter into these matters here.

Sub-phylum B—ANGIOSPERM A,

Ovules contained in closed ovaries. Pollen received on a specialized portion of
the carpel known as the stigma, and fertilization achieved by means of pollen-tubes
which penetrate hence to the ovule.

Angiosperms fall naturally into two classes, Monocotyledones and Dicotyledones.

Class I—MONOCOTYLEDONES.

Includes Flowering Plants whose flowers typically have their parts arranged in
whorls of three, embryos with one cotyledon, vascular bundles scattered through the
stem and not thickened by a cambium, leaves usually parallel-veined.

The Monocotyledones may be divided into 6 alliances:—Liliiflore, Scitamines,
Gynandre, Fluviales, Spadiciflore, and Glumifilore.

Alliance XXIX.—Liliiflore.

Families: Juncacee, Liliacea, Amaryllidacece, Iridacece, Dioscoreacee, Brome-
lViacew, Commelynacee, Pontederiacece.

In this alliance the flowers are actinomorphic, and their parts arranged in whorls
of three, i.e. two whorls constituting the perianth, two (or one) whorls of stamens,
and a whorl of three carpels united together. This condition may be briefly repre-
sented by the following formula:—P3+3, A 3+3, G (3), in which P, A, and G stand
for perianth, andreecium, and gyneceum respectively. The bracket inclosing the
number of carpels indicates that they are united (syncarpous). The ovary is
3-celled, and may be either superior or inferior; the seeds contain endosperm.

The Liliflore are for the most part herbs with perennial underground bulbs,
corms, and rhizomes. In relatively few cases is a permanent above-ground system

ANGIOSPERMEZ, MONOCOTYLEDONES. 729

Fig. 412,—Liliiffore.

1Gagea lutea. 2 Galanthus nivalis. 8 Leucojum vernum. 4 Colchicum autumnale, in flower and in fruit. 5 Section of capsule
of Colchi 6 Bulbocodt 7 Convallaria majalis. 8 Stigmas and stamens of an Iris.

730 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

produced. With the exception of the Juncacew the flowers are conspicuous and
brightly coloured.

Juncacece—Plants of grass-like habit with inconspicuous glumaceous perianth,
six stamens, and superior ovary, which is 3- or 1-celled. Pollination by wind.
Pollen-grains united into tetrads. Two well-known genera represented in this
country are Juncus (with about 190 species), which includes the Rushes, and
Luzula, the Woodrush. In all there are some 250 species of Juncacez.

Liliacee.— Herbaceous plants with bulbs, rhizomes, and corms, conspicuous

Fig. 413.—Asphodelus ramosus at Paestum (Southern Italy). [i

flowers with petaloid perianth, stamens 6, carpels 3, united, ovary 3-celled superior.
Pollination by insects. Fruits are capsules or berries.

A number of tribes may be distinguished: (1) Colchicacee having usually
extrorse anthers, septicidal capsules, and distinct styles. They include Veratrum,
Colchicum wutwmnale, the Meadow Saffron (fig. 412 *), which sends up its flowers in
autumn, its leaves and ripening capsule next spring. Bulbocodiwm (fig. 412°) is
frequent in cultivation. The Bog Asphodel (Nartheciwm) also belongs to this
tribe. (2) Asphodeloidew include forms generally with rhizomes, rarely bulbs;
anthers introrse, fruits capsular. Examples are Asphodelus, eg. A. onans
(fig. 413), which covers considerable tracts of country in southern Europe, forming
regular plantations, and was supposed to carpet the Elysian fields; Paradisea

S i
a
So
i ge ee
5 :

\NY WA

? S
LZ = es

—— et

so
Qe

PLATE XVI
x I

EUCALYPTUS GROVE AND GRASS-TREES IN AUSTRALIA.

Printed from the originals by the BIBLIOGRAPHISCHES INSTITUT, Tiss

ANGIOSPERMZ, MONOCOTYLEDONES. 731

Likiastrum, a beautiful alpine plant; Hemerocallis, the Day Lily; Phormiwm
tenax, the New Zealand Flax (fig. 414), the leaves of which yield a valuable
fibre; Knephofia, whose dense spikes resemble a red-hot poker, cultivated in
gardens; the Aloes and their allies, chiefly African, with a permanent aérial
branch-system; finally, the Australian Grass-trees (eg. Xanthorrhaa hastilis, shown
in Plate XVI.), often a conspicuous feature in the landscape, and with its long
spicate inflorescence sometimes attaining a height of 3 metres or more. This
plant yields a valuable gum. (3) Allioidew, usually bulbous, and having flowers

Fig. 414.—Phormium tenaz, the New Zealand flax. |

in umbels, They include the Onion tribe (Allium, of. fig. 311, p. 886), of which
A. cepa the Onion, A. porrwm the Leek, A. ascalonicum the Shallot, A. sativwm
the Garlic, A. schenoprasum the Chive, and A. scorodopraswm the Rocambole, are
cultivated. Gagea (fig. 4121) also belongs to this group. (4) Lilioidee have
bulbs, anthers introrse, and loculicidal capsules. Styles generally united. They
include numerous familiar and beautiful plants: Liliwm (45 species), Fritillaria (40
species), Hrythroniwm the Dog-tooth Violet, Tulipa (50 species), Scilla, Hyacinthus,
Ornithogalum the Star of Bethlehem, Muscari, &c. (5) Dracenoidee is an
interesting tribe, as it includes the Yuccas and Dracenas, which possess a per-
manent aérial system, which exhibits what is very exceptional amongst Monocoty-
ledons, a secondary thickening of the stem. Dracwna Draco, the Dragon-tree of

732 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

the Canaries, attains huge dimensions and a great age, and is altogether peculiar
among this type of vegetation. The flowers of Yucca (fig. 415) are represented on
p. 157, and its pollination described. (5) Convallariacew have rhizomes and berries.

san

Fig. 415.—Yucca gloriosa (from a photograph). ie n

They include Convallaria majalis the Lily of the Valley (fig. 4127), Polygonatum,
Aspidistra, Asparagus, Trillium, Ruscus (vol. i. p. 383), and Herb Paris (Paris
quadrifolia)—the last-named with the parts of its flowers in fours, (6) Smila-
cordece, which include climbers with net-veined leaves, eg. Smilaw.

ANGIOSPERM, MONOCOTYLEDONES. 733

Heth

nt
oo
iy

‘i A J tup, s

MM

ae
oR: =e

as

Fig. 416.—Aichmea paniculata (after Baillon).

734 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Amaryllidaceae.—Resemble Liliaceae, but have inferior ovaries, and in many

cases a corona to the perianth. They include the Snowdrop (Galanthus nivalis,
fig. 4127), Snowflake (Leucojum vernum, fig. 412°), Clivia, Amaryllis, Crinum,
Narcissus (with well-marked corona, fig. 248, p. 177); also, Agave and Fowrcroya
(ef. vol. i. p. 657).
' Iridacew.—Resemble Amaryllidaceae, except that they have three stamens only,
with extrorse dehiscence. The stigmas are commonly very conspicuously developed.
They include the Iris (figs. 412° and 265), Crocus (fig. 228, p. 118), Gladiolus, the
flowers of the last-named being slightly zygomorphic, and many others.

Bromeliacew.—Possess distinct calyx and corolla. Ovary superior or inferior;
fruit a berry or capsule. The family is tropical American, and very many of its
members are epiphytes, showing interesting adaptations to this particular mode of
life. The accompanying fig. 416 of the Peruvian Aichmea paniculata gives a
good idea of their mode of growth, with rosette of tough, leathery, sword-shaped
leaves and dense, terminal inflorescence. Not infrequently the bracts which
accompany the flowers are very brightly coloured. Two of the chief tribes of this
family are Tillandsiew, with capsular fruits, hairy seeds, and entire leaves; and
Bromeliee, with baccate fruits and toothed leaves (cf. fig. 416). The former includes
the rather aberrant Tillandsia wsneoides (ef. vol. i. p. 614), a widely-distributed
American epiphyte which covers trees much in the same way as does the Lichen
Usnea barbata in temperate zones. To the Bromeliee belong numerous forms,
including the Achmea figured here, and the Pine-apple (Ananassa sativa), the
various portions of the fruiting-spikes of which become entirely succulent and con-
fluent, forming the collective fruits referred to on p. 436.

The family includes about 400, and the whole alliance over 4000 species.

Alliance XXX.—Scitaminee.
Families: Musacee, Zingiberacee, Cannacee, Marantacew.

This alliance includes tropical plants with rhizomes and large conspicuous
leaves. In the flowers there is more or less reduction of the andreecium, often com-
bined with a production of petaloid staminodes. The ovary is inferior, and usually
3-celled, and the seeds, which are often inclosed in arils, have perisperm. The
flowers are zygomorphic, or destitute of any sort of symmetry. As a whole this
alliance is one of the most remarkable amongst the Monocotyledons.

Musacece.—The flowers of this family agree most nearly with those of typical
Monocotyledons. Of the six stamens one only is absent or developed as a stami-
node. The flowers are zygomorphic. They include Musa sapientum (the Banana)
and M. paradisiaca (the Plantain), widely cultivated for their fruits; Strelitzia,
a remarkable South African genus, and Ravenala Madagascariensis, the Traveller’s
Tree, so named from the water which accumulates in the excavated sheaths of the
leaf-stalks. This plant attains a height of 10 metres, and has a remarkable appear-
ance (gf. fig. 417) owing to the fact that its huge leaves (amongst the largest in the

ANGIOSPERMA, MONOCOTYLEDONES. 735

Fig. 417.—The Traveller's Tree (Ravenala Madagascariensis). After a drawing by Selleny.

736 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

vegetable kingdom) are borne in one plane. The fruits are large capsules, and the
seeds are inclosed in arils with blue metallic lustre.

Zingiberacee.—One stamen, the posterior of the inner whorl, alone is fertile.
The two others of this whorl are joined together to form a petaloid structure—the
labellum. Here are included the Ginger (Zingiber), Alpinia (fig. 2831, p. 289), and
Hedychium, cultivated for the beauty of its flowers; also Globba and Mantisia (the
Opera Girl) with flowers altogether remarkable; M. saltatoria presents some resem-
blance to a ballet-dancer, hence the name.

Cannacee.—Flowers altogether asymmetrical. The fertile stamen possesses
only a half-anther and several petaloid staminodes are present forming the most
conspicuous portion of the flower. Canna indica, the Indian-shot, and other species
are much cultivated, and have given rise to numerous brilliantly-coloured hybrids.

Marantacee,—Have asymmetrical flowers and a fertile half-stamen only. The
other stamens are moditied into peculiar staminodes, and the family is nearly allied
to Cannaces. Arrowroot is obtained from the rhizomes of species of Maranta.

The Scitaminez: includes about 600 species.

Alliance XX XI.—Gynandre.
Families: Orchidacew, Burmanniacee.

Flowers with petaloid perianth and inferior ovary. The stamens reduced to
one, two, or three, and generally united with the gyneeceum to form a column
(hence the name Gynandre). The fruits are capsules, and the seeds exceedingly
small and numerous.

Orchidacee.—After the Composite, the largest family of flowering plants,
numbering some eight thousand or more species. Its members are chiefly tropical
epiphytes, and their mode of life has received frequent mention in vol. i. Very
characteristic of the Orchid flower is the median petal, developed as a labellum (cf.
fig. 258' p. 227, and fig. 268? p. 255). The family may be divided into two divi-
sions according to the number of stamens present.

Division 1. Diandre—Having usually two polliniferous stamens and a large
and conspicuous staminode (which corresponds to the single fertile stamen of the
Monandre). The Lady’s Slipper (Cypripedium, ef. figs. 267! and 2672, p. 249,
and description on p. 253) is the best-known representative of this division. A
little group of plants, the Apostasiaces, is also included here. To it belongs
Newwredia, with 3 fertile stamens (i.e. the two found in Cypripedium and the one
which is represented by the staminode).

Division 2. Monandre.—Includes the greater portion of the family, with one
stamen only united with the gynaceum into the column and producing pollen in
masses (pollen-masses). The single stamen is inserted above the stigmatic surface,
from which it is separated by the rostellum, and is on that side of it which is
away from the labellum, the usual alighting place for insects. The structure of the
monandrous Orchid flower having been fully described and figured (pp. 253-257),

ANGIOSPERM, MONOCOTYLEDONES. 737

repetition is not needful here. The Monandre may be divided into four tribes, the
Ophrydece, Neottiew, Vander, and Epidendrecee.
The Ophrydew include most of the British and European Orchids, which are not

SS :
a tree-trunk (Madagascar). ua

Fig. 418.—Angreecum eburneum epiphytic on

epiphytes but terrestrial, with swollen tuberous roots, including Orchis, Ophrys,
Gymnadenia, Habenaria, and the South African Disa.

The Neottiew also include some European forms, Cephalanthera, Listera ovata.
(the Twayblade), &., and a series of colourless forms of saprophytic habit, which
are destitute of foliage, including Epipogium aphyllum (fig. 257 p. 226), Neottia

7

VoL. II. 9

738 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Nidus-avis (the Bird’s Nest Orchid), and Corallorhiza (the Coral-root). To this
tribe belongs the climbing Vanilla-orchid (Vanilla planifolia) the capsules of
which yield the spice.

To the Vande and Epidendree belong the numerous tropical epiphytes of
which many genera are widely cultivated in greenhouses, such as Lelia, Epiden-
drum, Cattleya, Masdevallia, Phajus, Catasetwm, (figs. 275» 2% 456% p, 269), Stan-
hopea (Plate XIII.), Phalenopsis (fig. 2581, p. 227), Odontoglossum, (Plate XIIT),
Dendrobium (fig. 275°), Oncidiwm (Plate XIITL.), Angrecwm (fig. 418), and many
others besides (vol. i. Plate IIT.).

To give any idea of the enormous varieties of floral structure met with among
the Orchids would require a whole volume. In this family of all others do we
find adaptations to insect visits carried out on a gigantic scale, and in not a few
cases mechanisms of singular beauty and delicacy. For ‘full details Darwin's
Fertilization of Orchids should be consulted.

Burmanniacee.—A small family of some 60 species, largely represented in
Borneo and New Guinea, is of interest, as it seems to connect the highly specialized
Orchidacese with more typical Monocotyledons like Amaryllidacew. They have
curious flowers; with three or six stamens, and several of them are saprophytie.

Alliance XX XII.—Fluviales.

Families: Potamogetacew, Naiadacew, Aponogetacee, Juncaginacee, Alismacec,
Butomacee, Hydrocharitacec.

This alliance includes a large number of aquatic forms, some with narrow, some
with broad leaves. The gyneceum is superior, except in the Hydrocharitacee.
The stamens and carpels show a tendency to an increased number as compared
with typical Monocotyledons. On the other hand, many forms with reduced
flowers occur. Endosperm is generally absent.

Potamogetacece.—Include chiefly submerged forms, some of which raise their
inflorescences above the water-level, and are wind-pollinated (Potamogeton, fig. 419),
whilst the others, including the Sea-grass (Zostera marina), Zannichellia, &c., are
pollinated below the water. Potamogeton (Pondweed) is a large genus of some
50 species, met with in fresh and brackish water; Zostera: grows on sandy shores
between tide-levels, often forming extensive belts. The embryos in this family are
peculiar. They consist of a much-thickened hypocotyl with a relatively small
cotyledon inserted upon it. They are termed macropodous.

There are about 74 species of Potamogetacez.

Aponogetacec.—Contains two interesting genera, Aponogeton and Owvirandra.
The plant is submerged, and raises a spicate inflorescence (often forked) above the
water. The flowers are imbedded in the spike, and consist of some 6 stamens and
3 free carpels, and a small number of perianth-segments. A ponogeton distachus
is often cultivated in this country on account of its beautiful white flower-spikes,
Ouvirandra fenestralis is the Lattice-leaf plant of Madagascar.

ANGIOSPERMZ, MONOCOTYLEDONES, 739

There are 15 species in all.

Alusmacece.—Possess a 6-leaved perianth, and stamens with tendency to increase
by division; carpels numerous. Here are included Alisma Plantago, the Water
Plantain, and Sagittaria sagittifolia, the Arrowhead.

There are about 50 species.

Butomacec.—Includes Butomus wmbellatus, the Flowering Rush, interesting.
from the fact that it bears ovules all over the internal surface of its carpels.

Fig. 419.—Curled Pondweed (Patamogeton crispus). fT ibranc |

Hydrocharitacee.—Is distinguished from the foregoing families in that it
includes submerged forms with infericr ovaries. The flowers are frequently uni-
sexual, and in one form (Halophila) are pollinated under water, as in so many of
the Potamogetaceew. To this family belong Vallisneria (see fig. 155, vol. i. p. 667
and fig. 227, p. 182), Elodea, the American Water-weed (alluded to on p. 457),
Lagarosipon and Enalus (p. 183), Stratiotes aloides, the Water-soldier (vol. 1. p. 552)
and Hydrocharis Morsus-rane, the Frog-bit, with expanded floating leaves.

Contains about 60 species.

740 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Alliance XX XIII.—Spadiciflore.

Families: Palmacew, Aroidec.

Monocotyledons with small and usually unisexual flowers crowded on spikes or
spadices, and inclosed in one or more conspicuous sheaths, the spathes. The ovaries
are superior.

This alliance may be contrasted with the group Composite of Dicotyledons in
which also the individual flowers are merged in dense crowded inflorescences which
superficially resemble single flowers (cf. Arum and Chrysanthemum).

Palmacec.—Include plants with cylindrical, woody stems and tough fan-shaped
or feather-like leaves of large dimensions having a plaited vernation. The flowers
are borne in branched, fleshy spikes often inclosed in large sheathing leaves; they
are hermaphrodite or unisexual and actinomorphic; the parts are arranged in threes,
and are inconspicuous. The gynzceum consists of three carpels, each containing
one seed. Stamens six, pollen dust-like. Fruits are berries, drupes, and nuts, and
contain three, or by suppression, one seed. The endosperm is copious, and generally
hard and stony. The majority of Palms possess upright, columnar caudices sur-
mounted by a huge tuft of crowded leaves (cf. vol. i. p. 289, and Pl. VIII). In
several species the caudex attains a height of 30 metres, and in one (Ceroxylon
andicola) 57 metres, The Climbing Palms have slender branched stems, and by
the aid of the hooks on their leaves mount to the summit of trees and stretch like
lianes from crown to crown (¢f. vol. i. pp. 863, 675, and 676). The stems of these
Palms reach a length of 150-200 metres, and yield the rotang cane. The opposite
figure shows the interior of a forest penetrated by Climbing Palms and two natives
rolling the stems into a coil. Old Palm-stems are either smooth and show the scars
of the fallen leaves, or they still bear the disintegrated fragments of former foliage-
leaves. Others again are armed with spiny girdles and scales. The leaves are
folded in bud and undivided, and as they unfold they split along the creases, and
the blade is divided pinnately or like a fan; we may distinguish between the
feather-leaved and fan-leaved Palms. Often in young Palms the leaf splits at the
apex into two pointed lobes only, as in Areca disticha, represented the foreground
of fig. 420. The dimensions of Palm-leaves and the gigantic inflorescence of the
Talipot Palm (Corypha wmbraculifera) have already been alluded to (ef. vol. i. pp.
287 and 745). In Oreodowxa regia the sheathing base of the leaf attains a length of
2 metres and a half. The fruits of many species (e.g. Chamerops excelsa) are borne
in grape-like bunches; in others they attain to great size and weight. The Double
Cocoa-nut, the fruit of Lodoicea Sechellarum, is prominent in this respect (of.
p. 452).

Most Palms are eminently tropical in their distribution. Some genera are met
with throughout the tropics, others (eg. Mawritia, Oreodoxa, and Iriartea) are
confined to the New World; others again, as Borassus (B. flabellifornvis, Pl. VIIL).
Raphia, Caryota, and Calanws to the Old. Chamerops humilis, alone of the

ANGIOSPERMZ, MONOCOTYLEDONES, 741

f OWicte
Be Iversif

ibrar re

Fig. 420. —Primeval forest in Ceylon with Climbing Palms (Calamus) and Areca disticha in foreground to the right. (Drawn
from nature by v. Ransonnet.)

742 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Palms is indigenous to Europe; Cerowylon andicola, is found in the Andes growing
at a height of 270 metres. Fossil remains are found in the formations of the
secondary and tertiary formations. The number of living species is about 1100.

Aroidee.—Perennial vlants with tubers, rhizomes, and climbing stems which

Fig. 421.—Aroids.

1 Arum maculatum. 2%Spadix of A. maculatum, the spathe removed. % Fruiting spike of same. 4Inflorescence of Colocasia
antiquorum. 5 Basal portion of this inflorescence with part of spathe removed. Ovary of Colocasia antiquorum. 7The
same in longitudinal section. 8Columnar andrecium of same. ° Ariopsis peltata. 2, 6, 9 nat. size; 1, 3, +reduced;
67,8 enlarged. g

generally bear large foliage-leaves." The flowers are borne on unbranched, fleshy
spadices .which are inclosed in large, expanded spathes (cf. figs. 4211445°); they
are unisexual or hermaphrodite. The parts are inserted in whorls of 2 or 3; the
perianth-members being inconspicuous and often absent. The andrcecium is very
various. In Colocasia antiquorwm (fig. 421%) it consists of a whorl of stamens

ANGIOSPERMZ, MONOCOTYLEDONES. 743

THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

= = —= : Ss =) “
ig. 423.—Climbing Aroids (Philodendron pertusum and P. Iinbe) with cord-like aérial roots.

AUER
p n¢

ANGIOSPERME, MONOCOTYLEDONES. 745

united into a single abbreviated column. Endosperm is present in the seeds. The
tribe Pistee includes floating plants with leaves arranged in rosettes and propagat-
ing vegetatively by means of stolons. The Are, of which the Arum (figs. 4211} % ®)
may be taken as a type, have subterranean tuberous stems, from which arise the
leaves and spadices. Numerous representatives of other tribes, including Aviopsis,
Caladium, Dracontiwm, and Amorphophallus have tubers. Amorphophallus
titanwm, the giant of this family, has a tuber 50 centimetres in diameter, and
produces umbrella-like leaves on stalks 2-5 metres long and with segments in
proportion. The inflorescence is a huge spadix some 2 metres high, encircled by
a sheath of beautiful mottled green with purple lining and frilled edge. When this
plant flowered at Kew in 1890 (for the first and as yet only time in captivity) it
was one of the sensations of a London season. It is a native of Sumatra. A few
species of Montrichardia (M. linifera) and Philodendron (P. bipinnatifidum)
have erect cylindrical stems, whilst the Snake-root (Calla palustris). and Sweet
Flag (Acorus Calamus) have creeping rhizomes. Many tropical Aroids belonging
to the tribes Monsteree and Pothoideew climb up the stems of trees, fastening
themselves by their aérial roots, and pass from crown to crown like lianes. The
Himalayan Raphidophora decursiva (fig. 422) is an example of this type of growth.
Many of these climbing Aroids send down pendent aérial roots into the humid air
of the forest (fig. 423), and these not unfrequently reach the ground, take root, and
become stretched taut.

The majority of Aroids are tropical, less than 10 per cent of the species being
met with in temperate regions. Acorus Calamus, Arum maculatum, and Calla
palustris reach the furthest north. The curious Ariopsis peltata (fig. 421°) occurs
in the Himalayas to a height of 1600 metres.

There are about 900 species of living Aroids.

The Lemnaceew is a little family of reduced forms allied to Aroideew. The
flowers are unisexual, and consist of a stamen and a carpel respectively. They are
floating, flattened forms, and include Lemna (the Duckweed), and Wolffia, which is
destitute of roots.

Associated with the Spadicifloree are the Pandanacee, which include Pan-
danus utilis, the Serew Pine (ef. vol. i: fig. 186, p. 758); Cyclanthacez, climb-
ing and palm-like; Sparganiacee and Typhacee, marsh plants, which include
Sparganium, the Bur-reed, and Typha, the Bulrush.

Alliance XXXIV.—Glumiflore.
Families: Graminece and Cyperacee.

This alliance, which includes some 6000 species, consists exclusively of Grasses
and Sedges, forms with insignificant flowers destitute of coloured perianths and
pollinated by wind.

Graminec.—Annual and perennial plants with upright, jointed haulms, and in
the case of perennials, provided with creeping rhizomes. The leaves consist of an

746 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

undivided, linear, parallel-veined lamina (vol. i. fig. 150°), and a sheathing basal
portion. At the junction of blade and sheath is inserted a little scale—the ligule.
Flowers hermaphrodite and unisexual, arranged in spikelets (cf. fig. 231, p. 189).
Perianth absent, its place being taken in many cases by 2 tiny scales, the lodi-
cules, sometimes regarded as reduced perianth-leaves. Each flower is inclosed in a
sheathing scale known as a palea, whilst outside this and subtending the flower is a
bract-like structure, the flowering glume; this is often awned. Every flower is thus
inclosed in a palea and flowering glume, whilst the whole spikelet is inclosed in a
little 2-leaved involucre consisting of 2 outer glumes. The ovary bears 2 feathery
stigmas, and contains a single ovule. The stamens are generally 3 in number,
though variations are met with. The pollen is dust-like. Pollination has been
fully described on pp. 140-142. The fruit or grain is indehiscent, and is known
as a caryopsis. The seed contains a floury endosperm, and an embryo placed at
one side (ef. vol. i. figs. 141% 45, p. 599). The internodes of the haulm are in Zea,
Andropogon, Panicum, &e., filled with pith; in the majority of Grasses they are
hollowed. The Bamboos and numerous other tropical Grasses have upright
perennial stems, and form an arborescent vegetation (¢f. vol. i. p. 713). Bamboos
attain a height of 25 metres and a diameter of nearly half a metre. But the
majority of Grasses produce new haulms each year from their subterranean
rhizomes, and these die down at the end of the season. The female flowers of the
Maize (Zea Mars) are borne on thick spadices (cobs) inclosed in sheathing bracts.
Grasses are widely distributed over the globe, the tropics being richer in species
than the temperate regions, but poorer in individuals. Grasses are found extending
into arctic and alpine regions to the extreme limits of phanerogamic vegetation;
thus in the Alps Poa lava has been found at an elevation of 3000 metres. The
Bamboos are tropical and sub-tropical; in the Steppes certain Grasses are very pre-
dominant, e.g. the genera Stipa and Festuca (cf. Plate VI. vol. i. p. 616). In moist,
temperate climates, Grasses form a continuous carpet, the basis of meadow land. In
marshy places and by river banks reed-like Grasses occur in great quantities (eg.
Phragmites communis).
Graminez number about 3500 species.

_ Cyperacece.— Annual and perennial plants with upright, haulm-like stems,
jointed below and with long upmost segment. The leaves much resemble those of
Graminee, but the ligule is wanting. Flowers hermaphrodite and unisexual, aggre-
gated into spikelets, inclosed in bract-like scales. Perianth absent, or represented
by scales, bristles, or hairs. The ovary is 2- or 3-carpellary. Stamens in one or
two whorls of 3 each; pollen dust-like, pollination by wind. The seed contains
endosperm. In the Scirpew the leaf-blades are frequently obsolete, and assimila-
tion is carried on by the stems. Scirpus lacustris reaches a height of 1, Papyrus
antiquorum (or Cyperus Papyrus, fig. 424) of 3 metres and a diameter of 10 centi-
metres. The pith of the larger flowering stems of this plant cut into thin strips,
united together by narrowly overlapping margins, and then crossed under pressure
by a similar arrangement of strips at right angles, constituted the papyrus of

ANGIOSPERMA, MONOCOTYLEDONES. 747

|

| : ,

e

748 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

antiquity; it grows in the Upper Nile, Syria, Palestine, &. The stem of Papyrus
bears at the summit an umbel-like tuft of filamentous branches, upon which the
inflorescences arise. Cyperacess grow for the most part on damp moors, and by
the banks of streams and lakes, and in mountain regions. Many of them are social
forms, noteworthy in this respect being Carex stricta, which forms hummocks in
marshy places, standing up above the water, often thousands together. Several
Sedges, e.g. Carex sempervirens and C. firma, contribute largely to the turfy carpet
of alpine slopes (cf. Plate XII).

The family is distributed over the whole world. Carea, Eriophorum, and
Scirpus are found especially in cooler and northern zones; Cyperus and Papyrus in
warmer regions. About 2500 species are known.

Class II.—DICOTYLEDONES.

Flowering Plants whose flowers typically have their parts arranged in whorls
of four or five, embryos with two cotyledons, vascular bundles arranged in a ring
and undergoing a secondary increase in thickness, leaves more complex than in
Monocotyledones and usually reticulately veined.

The Dicotyledones may be divided into three Sub-classes: Monochlamydee,
Monopetale, and Polypetale. The Monochlamydex have a simple perianth, or in
some cases the perianth may be wanting. The Sub-class is an artificial one, as it
includes forms whose ancestors probably possessed a double perianth and others
which are primitively simple. The Monopetale and Polypetale possess both calyx
and corolla; in the former the parts of the corolla are united together, in the latter
free.

Sub-class I.—MonocuLamMyDE&,

Alliance XXX V.—Centrosperme.

Families: Piperacee, Polygonacee, Cynocrambacee, Urticacee, Chenopodiaceer,
Nyctaginacee, Amaranthacee, Paronychiacee, Caryophyllacece.

Annual or perennial herbs, shrubs, and trees. Venation of the leaf-blades
palmate or pinnate. Flowers solitary or in cymes; the cymes arranged in fascicles,
glomerules, or spikes. Flowers actinomorphic, hermaphrodite, pseudo-hermaphrodite,
moncecious, and dicecious. Floral-leaves in one or two whorls; all sepaloid, all
petaloid, or (in a few cases) the outer whorl sepaloid and the inner whorl petaloid.
Where a corolla is developed the petals are free. In the case of dicecious flowers
there is no difference between the male and the female flowers in respect of the
development of floral-leaves. The ovary is superior; 1-5-carpellary, unilocular.
The ovules are borne in the centre of the ovary on a stalk which rises from the
bottom of the ovary, and is sometimes long, sometimes short. Stamens 1-30, arranged
in one or two whorls, the outer ones inserted in front of the sepals or sepaloid
perianth segments. Fruit an achene, capsule, or berry. The seed contains an
abundant fariaceous or mucilaginous endosperm. Cotyledons not thickened.

ANGIOSPERM&, DICOTYLEDONES. 749

The Centrosperme are extremely rich in inorganic salts, and in the ease of many
of the species soda is extracted from the ash obtained by burning the plants. The
Piperacex contain aromatic and pungent substances; the Urticaces: secrete enzymes
in their stinging-hairs (see vol. i. p. 441). The leaves are lobed in Urticacee and
Chenopodiacew, in the rest they
are undivided and have entire
margins. In several Cheno-
podiacez the cauline leaves are
squamiform, and assimilation is (
then effected by the green cortex
of the branches, which are trans-
formed into phylloclades. The
Piperaceze are distinguished by
a peculiar distribution of the
bundles in the foliage-leaves.
The lateral strands do not branch:
off from the midrib in the usual
way, but are appressed to it and
can be traced to the base of: the
lamina. The Urticacez also,
particularly the genus Parie-
taria, exhibit a peculiar disposi-
tion of the bundles (see vol. i.
p. 629). The Chenopodiacez
are destitute of stipules, the
Paronychiacee have large mem-
branous stipules which protect
the foliage-leaves, the Poly-
gonacee are distinguished by
curious sheathing stipules. In
the Caryophyllacee and some
Paronychiacee the floral enve-
lopes are differentiated into
calyx a corolla; ad Nyetagin- Fig. 425.—Nyctaginacee, Mirabilis pang

acee, Amaranthacex, and most 1 Flowering branch. 2 Fruit inclosed in the persistent base of the peri-
Polygonaceze there is a petaloid anth. % Longitudinal section through the same; the true fruit is seen

within. (After Baillon.)

perianth, whilst in Chenopodi-

aceze and Urticacee there is a sepaloid perianth. The perianth in Nyctaginacee
resembles a corolla most strongly when the bracts are connate and form a
sepaloid envelope or involucre, as is the case, for instance, in the Marvel of
Peru (Mirabilis Jalapa, see fig. 425). The lowest portion of the perianth in
Nyctaginacez continues to grow after the flower has faded and forms a leathery
or woody investment to the fruit (see fig. 425%).. In several Chenopodiacee and.

~~ att,
Lgeriell
VEN IVERS
art

750 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Urticaceze also the perianth persists as a similar investment (eg. Morus). In
Amaranthacee the pedicels are furnished with bracts which resemble the perianth-
segments and, like them, envelop the fruit. In those Centrospermze which are
‘destitute of floral-leaves (achlamydeous), e.g. the Piperacee, the floral envelopes are
replaced by bracts. The Caryophyllacee have distinct calyx and corolla, and are
often placed in the sub-class Polypetale; they have, however, decided affinities with
the Centrosperme. The andrcoecium is composed of one whorl in Urticacee and
Chenopodiacez, and of two whorls in most of the other families. The filaments are
inflexed in the bud in Urticacez, but spring up when the perianth opens and so
eject the pollen from the anthers (see p. 306). Most of the Centrosperme have
dust-like pollen, but in Caryophyllacese and Nyctaginaces the pollen is adhesive.
In Urticaceze and in some Caryophyllacee the embryo is erect, in the rest it is
horse-shoe shaped or spirally curved (see fig. 425%). The copious farinaceous
endosperm of some Polygonaceze and Chenopodiacese (Polygonum Fagopyrum,
P. Tataricum, Chenopodium Quinoa) is used for flour. The Centrosperme are
distributed in every quarter of the globe. The Piperacew, Urticacex, Polygonaces,
Amaranthacee, and Nyctaginacee are developed in the greatest variety in the
tropics. Most Centrosperme, however, are found in the temperate zones. The
Mediterranean Flora is especially rich in Caryophyllacex, whilst Equatorial America
abounds particularly in Amaranthacee and Nyctaginaceew. The Polygonacer grow
chiefly on the banks of streams; the Chenopodiacee are very prevalent by the
sea-shore and on salt steppes, especially in Central Asia. Several Caryophyllacee
flourish also on the confines of perpetual snow. Silene acaulis (see Plate XII) is
one of the most remote outposts of the Phanerogamia and has been met with in
Franz Joseph’s Land at 81° north latitude, and in the Central Alps at a height of
3160 metres above the sea-level. Fossil remains of Urticaceee and Piperacez have
been recognized in the deposits of the Mesozoic and Tertiary periods. The number
of species now living amounts to about 4200.

Alliance XXX VI.—Proteales.
Family: Proteacee.

Perennial herbs, with underground stems which project but little above the
earth, or herbs and small trees with entire or variously lobed and incised stiff
foliage-leaves without stipules. Flowers in capitula or spikes (see fig. 426+); actino-
morphic or zygomorphic, hermaphrodite, pseudo-hermaphrodite, moncecious and
dicecious. Perianth 4-partite, petaloid; the four segments are connate at the base,
and, in the bud, have their free ends closed together like valves (see fig. 426°).
Ovary superior, free, unilocular. Number of ovules one to many. Placentation
parietal. Each ovule has a double integument; the micropyle is directed towards
the base of the ovary. The latter is surrounded by tissues which secrete honey.
The number of stamens is equal to that of the perianth segments; the short filament
is adnate to the perianth-segment behind it (see fig. 426°). Fruit a drupe, a nut,

ANGIOSPERM, DICOTYLEDONES. 751

a capsule or a follicle (see figs. 4264 and 4265, and fig. 324, p. 429). The seed
contains an embryo furnished with two large, thick, fleshy cotyledons, but no
endosperm.

The Proteales are for the most part much-branched shrubs. The arboreal

Fig. 426.—Proteales.

1 Banksia ericifolia. 2 Single flower of Banksia littoralis with the spoon-shaped perianth-segments still closed. 3 Longitudinal
section through the same flower; the style is in the form of a barbed hook, and the stigma rests between the anthers; the
filaments are adnate to the concave surfaces of the spoon-shaped périanth-segments. +4 Fruiting spike of Banksia ericifolia.
5 Fruit of Xylomelum pyviforme. 2 and % magnified; the rest nat. size. (After Baillon.)

species Knightia excelsa, a native of New Zealand, attains a height of 30 metres.
The foliage-leaves are sometimes glabrous and sometimes clothed with scales, and
they possess peculiar stomata (see vol. i. p. 296). The genus Hakea exhibits in

752 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

some of its species pinnate and bipinnate leaves, in others cylindrical and needle-
shaped leaves. The flowers, which are crowded together, are sometimes surrounded
by an involucre of many scales reminding one of the involucre of Composite. The
ovary is often borne on a special stalk. The style and stigma are very various. In
many species, as, for instance, in Banksia ericoides and B. littoralis (fig. 426°),
the style is hooked and breaks through the perianth-tube in consequence of the
excessive longitudinal growth of its lower region, but the capitate extremity remains
between the anthers, which are adherent to the spoon-shaped extremities of the
perianth. Only when the perianth segments disunite and open back does the top of
the style become free. The pollen is often deposited upon the end of the style with-
out, however, immediately reaching the stigmatic surface, and in many species there
are special hairs or brushes for collecting the pollen, whilst pockets and recesses for
its temporary reception also occur. The Proteales flourish chiefly in regions where
a short rainy season alternates a long rainless period. Australia and the south-west
district of the Cape are richest in species; the alliance is represented by many fewer
species in the tropical region of South America, in Chili, in New Caledonia, in New
Zealand, in the tropical parts of Eastern Asia, in Madagascar, and in the mountains
of tropical Africa. Fossil remains of Proteaces occur in strata of the Tertiary
Period. The number of existing species is about 1000.

Alliance XXX VII.—Daphnales.
Families: Elwagnacea, Thymelaceee, Lawracec.

Annual and perennial herbs, shrubs, and trees with green foliage, or leafless
parasites. Stipules absent. Flowers in fascicles (see fig. 427 1); actinomorphic, her-
maphrodite, pseudo-hermaphrodite, or dicecious. Perianth of one or two whorls of
2, 3 or 5 leaves each, sepaloid or petaloid. Gynaceum 1-3 carpellary. Ovary
unilocular. Style single, free, at the bottom of a cup-shaped receptacle from the
margin of which spring the perianth-leaves (see fig. 4272). Ovule solitary. An-
droecium 1-4 whorls with 2-4 stamens in each inserted on the inner margin of the
cup-shaped receptacle. Fruit a one-seeded berry, drupe, or nut. The seed contains
no endosperm. The embryo is furnished with large, fleshy cotyledons.

The Cassythx, belonging to the family Lauraces, are parasites poorly supplied
with chlorophyll, with thin twining stems and squamiform leaves. Most of the
Daphnales, however, develop woody stems with leafy branches. The leaves of
Hlxagnacee are clothed with scaly covering-hairs (see vol. i. p. 322, fig. 78°). The
foliage-leaves of most Lauracee exhibit a curious distribution of the strands in the
lamine (see vol. i. p. 631, fig. 1494, and accompanying fig. 4271). The majority of
Lauracee contain ethereal oils and aromatic substances. Especially to be mentioned
in this connection are the Bay-Laurel (Lawrus nobilis), the Cinnamon-tree (Cinna-
momum Zeylanicwm), and the Camphor-tree (Camphora officinarum). In the Sea
Buckthorn (Hippophae, see p. 109, fig. 220), the perianth is 2- and the andrcecium
4-membered; in Elwagnus the perianth and andrcecium are each composed of two

ANGIOSPERMZ, DICOTYLEDONES. 753

2-membered whorls; in Daphne the perianths has two 2-membered whorls, and the
andreecium two 4-membered whorls (see fig. 427%); in Lawrus the perianth consists of
two and the andreeciumn of four 3-membered whorls; in the genus Gnidiwm there are
two kinds of floral-leaves, the lower ones sepaloid the upper petaloid in colour, and
these are spoken of as calyx and corolla. The same arrangement is found in several
Lauracew. The anthers of Eleagnacess and Thymelaces dehisce by longitudinal
slits, those of Lauracew by valves (see fig. 427°). In the Eleagnacew the cup-
shaped receptacle persists as an envelope around the fruit, and becoming succulent

At

Fig. 427.—Daphnales.

1 Camphora oficinarum (Family Lauracee), flowering branch. 2% Longitudinal section through the flower of Cinnamomum
Zeylanicum (Family Lauracee). % Flower of Daphne Mezerewm (Family Thymelacex) cut open and rolled back
1 reduced: 2 and § magnified. (Partly after Baillon.)

outside and strong within, the result is a false drupe. In some of the Lauracee
also, as, for instance, in Nectandra, the receptacle continues to grow with the fruit,
and forms a cup-shaped envelope resembling the so-called cupule in the fruit of the
Oak. In Thymelacee and Lauracesw the ovule is pendulous (see fig. 4277), in
Eleagnacese it is erect. The Daphnales are scattered over all parts of the earth.
The Thymelacez are best represented in countries where the climate is temperate;
the Cape and Australia are particularly rich in species of that family. Daphne
striata attains its highest elevation in the Central Alps at 2500 metres. There is a
striking concentration of several species of the genus Daphne on a strictly limited
area in the mountainous parts of Southern Europe. One of these species is the

plant known in Carniola under the name of the Konigsblume (Daphne Blagayana).
Vou. IL 98

754 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

This name of King’s Flower was popularly accorded to the plant because, in 1838,
King Augustus of Saxony travelled to Carniola on purpose to see this rare species
flowering in its restricted habitat. The Lauracez are principally tropical and sub-
tropical plants; Eastern Asia, the Sunda Islands, and Brazil are especially rich in
species of this family. The Lauracez reach their northernmost boundary below
50° in Eastern Asia, below 46° in Europe, and below 45° in North America. In the
Southern Hemisphere the Lauraceew range as far as 43° S. lat. Fossil remains of
the Daphnales, especially of Lauraces, are found in the strata of the Mesozoic and
Tertiary Periods. The number of existing species hitherto discovered is about 1400.

Alliance XXX VIII.—Santalales.
Families: Santalacece, Viscacece, Loranthacece, Olacacee, Grubbiacew.

Herbs, shrubs, and trees, of which most are parasitic on the roots and stems of
other green-leaved Phanerogams, although they are themselves capable of assimila-
tion owing to the presence of chlorophyll in the foliage-leaves. The leaves have
entire margins; there are no stipules. Flowers actinomorphic, solitary or in cymes,
which are combined into spikes, racemes, umbels, and capitula; hermaphrodite,
pseudo-hermaphrodite, moncecious, and dicecious. Perianth composed of 2- or 3-
membered whorls; either sepaloid or petaloid. Gynzceum 2-3 carpellary; ovary
sunk in the discoid or cup-shaped receptacle, inferior or semi-inferior, unilocular.
Style single. Ovules 1-5, without integument. Stamens as many or double as
many as the perianth-segments; in the former case they are inserted in front of
those segments. Fruit usually a berry or drupe. Seed-coat either single or absent ;
the embryo either partially or entirely surrounded by fleshy endosperm.

For a description of the sinkers and haustoria of the parasitic Santalacez see
vol i. p. 177 and pp. 205-213. Several of the Loranthacez have thin twining stems
which put out roots, i.e. sinkers, from their nodes. Such of the Loranthaces as
are destitute of green foliage-leaves have thickened and flat expanded branches.
In certain Santalaceze several bracts are united so as to form a cup-shaped
involucre. In Grubbiaceew and Olacaceze the lower portion of the ovary is
septate, at least in the first stage of development. In the Santalacee and some
Olacacez 1-5 pendulous ovules are borne upon a cellular structure which is either
adnate to the internal wall of the ovary or else rises freely in the cavity; in the
Loranthacez they completely fill the ovary, and are united with the carpels into a
solid mass. In Grubbiaceze the stamens of the outer whorl alternate with the
leaves of the perianth, and there are double as many stamens as perianth-segments.
The stamens of the Mistletoe (Viscum album, see p. 87, fig. 214") are adnate to the
perianth-leaves behind them, and their anthers have 6-20 loculi, each of which
liberates pollen through a pore. The Santalales are widely distributed. The
majority of the species are tropical and sub-tropical. The Olacacee only occur in
the tropical parts of South America and Africa, and the Grubbiacew only at the
Cape, whilst the Santalaceze are chiefly natives of Africa and Australia. The

ANGIOSPERM&, DICOTYLEDONES, 755

Mistletoe (Visewm albwm, found in Scandinavia as far north as 59° 30’) and several
species of the genus Thesiwm reach furthest north. Thesiwm alpinum attains its
highest limit in the Alps at 2400 metres. Fossil remains occur in the strata of the
Tertiary Period. The number of existing species is about 750.

Alliance XXXIX.—Rafflesiales,
Families: Rafilesiacee, Apodanthacew, and Cytvnacece.

Plants destitute of chlorophyll, parasitic on the roots of green-leaved woody
plants. . Flowering axis greatly thickened, fleshy, Flowers solitary or in racemes,
hermaphrodite or pseudo-hermaphrodite. Perianth 4-6 partite. Ovary inferior.
The cavity of the ovary is divided irregularly into chambers which are filled with
strands and ridges bearing the ovules. Above the ovary rises a columnar style
with a discoid thickening at the top, and upon the under margin of this dise the
stigmatic tissue is situated. The stamens are inserted underneath the stigmatic
tissue in a circle. The fruit is fleshy, baccate, and crowned by the persistent
column. The seeds have hard coats. The embryo consists of few cells, has no
cotyledons, and is surrounded by an oily endosperm. For a description of the
suction-organs see vol. i. pp. 199-204, and for the size of the flowers see vol. ii.
p. 185. The Rafflesiales live in the tropical and sub-tropical regions of both the
Old and the New World; two species of the genus Cytinus (see vol. i. p. 201) belong
to the Mediterranean flora. No fossil remains are known. The number of extant
species hitherto identified is 29.

Alliance XL.—Asarales.
Families: Aristolochiacee, Aswracec.

Perennial plants, some with subterranean tuberous or creeping rhizomes, some
with twining liane-like stems (see vol. i. fig. 951, p. 364). Foliage-leaves broad, with
entire margins, sometimes lobed. Venation apical (see vol. i. p. 633). Flowers
hermaphrodite, solitary, or in cymose inflorescences, especially in axillary fascicles.
Perianth of 3 petaloid leaves, united at the base. Gynaceum 4-6 carpellary; ovary
inferior or semi-inferior. Styles united into a column bearing a radiating stigma.
Andrcecium composed of 2-12 whorls of 3 stamens each. Ovules numerous in the
loculi of the ovary. Fruit a capsule (see p. 431, fig. 3255). The seed contains an
abundant endosperm, and a very small embryo with two cotyledons.

The perianth in Asaraceze is actinomorphic (see p. 279, fig. 2791218), whilst in
Aristolochiacee it is zygomorphic or else unsymmetrical, and the tube of the peri-
anth is variously curved and inflated (see p. 166, fig. 242, and p. 226, fig. 257 6 7:8 9),
These flowers are very striking, on account not only of their form, but also of
their dark-brown colour; moreover, in many cases they attain to an extraordinary
size. Mention has already been made of Aristolochia gigas (see p. 185), and
recently a Birthwort (Aristolochia Goldeana) has been found in West Africa which

756 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

has a perianth 66 cm. long and 28 cm. broad. In the Asaraces there are some-
times three small teeth alternating with the three perianth-segments, and these
are looked upon as reduced inner perianth-segments. The stamens of Aristolo-
chiacez are adnate to the stylar column (see p. 292, fig. 284"). The Aristolochiacese
are distributed in all parts of the world. The majority of the species are found in
tropical and sub-tropical regions. The genus Aswrwm reaches furthest north. The
northern limit of the Asarabacca (Asarum Europewm) and its highest elevation
are the same as those of the Beech. Fossil remains are found in the strata of the
Mesozoic and Tertiary Periods. The number of extant species hitherto identified is
about 200.
Alliance XLI.—Euphorbiales.

Family: Euphorbiacee.

Annual and perennial herbs, shrubs, and trees. Flowers in racemose’ or umbel-
late cymes; actinomorphic, hermaphrodite, pseudo-hermaphrodite, moncecious, and
dicecious. Floral-leaves differentiated into calyx and corolla. Calyx and corolla
3-12-merous. The corolla is often suppressed, and sometimes the calyx also is
wanting. In these cases the floral-leaves are replaced by bracts and involucral
leaves. The gynzceum is superior, and is composed of 3-20 carpels, which are
arranged in whorls round a central column. The carpels are joined together to
form a multilocular pistil. In the inner angle of each loculus are 1-2 pendulous
ovules. The stamens vary in number from 1 to over 100. At the base of the
flower are some peculiar glands, which are looked upon as outgrowths of the
receptacle. They are either in the form of separate cellular structures, arranged
in a whorl, or else are coherent in the form of a cup. In the cases where these
structures do not occur they are replaced by similar glands, which are seated upon
the margin of the cup-shaped involucre. The fruit is a schizocarp or drupe;
sometimes it is baccate. The embryo is imbedded in an abundant fleshy endosperm.

It is difficult to describe the Euphorbiales in few words on account of their
extraordinary variety. Some of them contain watery juices; the majority are full
of latex. Several of the laticiferous species are poisonous. Many have green
foliage-leaves; whilst some are destitute of foliage-leaves, and assimilation is then
effected by means of the green cortical tissue of switch-like or cactiform branches
and phylloclades. In many genera, especially in Huphorbia, the inflorescences
have the appearance of being single flowers. A large number of male flowers are
assembled together within a cup-like involucre, the free edge of which is furnished
with glands as though with petals. Each of these flowers consists, however, merely
of a bract and a stamen, and in the midst of them is a female flower, borne at the
end of a long stalk, and resembling a stalked ovary. In many species of the genera
Croton and Powsettia the inconspicuous flowers are surrounded by bright-coloured
bracts and involucral leaves. In the majority of instances three carpels are devel-
oped, which are remarkable for their rotundity. They are laterally coherent, and
usually separate when mature, and become detached from the central column. The

ANGIOSPERME, DICOTYLEDONES, 757

Euphorbiales are distributed in every quarter of the globe. The majority are
found in the tropics, and several arboreal species form entire woods in those
regions. Some grow in marshy lowlands, whilst others inhabit steppes and the
rocky declivities of mountains. Huphorbia capitulata grows on the mountains of
the Balkan Peninsula. Euphorbia Austriaca stretches as far as the alpine region
of the Eastern Alps. Mercwrialis perennis attains in the Alps an elevation cor-
responding to the upper limit of the Beech-forests. Several annual species of
Euphorbia are encountered as weeds in cultivated ground, as far as the limits of
the arctic region. Fossil remains have not been definitely ascertained to exist.
The number of extant species hitherto identified is about 4000.

Alliance XLII—Podostemales,

Family: Podostemacee.

Perennial herbs with creeping roots which are fastened to the substratum. The
shoots spring laterally from these roots, and are clothed by small scales arranged in
two or three rows; these leaves are either entire or pinnately lobed, and they are
sheathed at the base. Not infrequently the shoots are transformed into phylloclades,
and sometimes shoots and roots are fused together into a thalloid structure. In
these cases the assimilation of carbon is effected by the phylloclades as well as by
the green branches of the thalloid tissue clinging to the substratum. The branches
in question are ribbon-shaped or filiform, and are submerged. The flowers occur
singly at the ends of the shoots, or else are sunk in the margins of the phylloclades
in rows, and together form a sort of flat club. They are actinomorphic and zygomor-
phic, hermaphrodite, moncecious, and dicecious. The floral-leaves are small, greenish,
squamous, free, or connate, and are arranged in a 3-5-partite whorl. When the
floral-leaves are suppressed, they are replaced by sheathing involucral leaves. The
gyneceum is composed of 1-3 carpels; the ovary is superior, and either unilocular
or else divided by delicate partition-walls into three chambers. The ovules spring
from cushions of tissue which project from an axial column in the ovary. The
number of stamens varies greatly, the flowers being either monandrous, diandrous,
or polyandrous. In the last case the stamens are arranged in several whorls. The
anthers dehisce longitudinally. The fruit is a capsule. The seeds are very small,
and do not contain any endosperm. The embryo has two thick cotyledons.

The Podostemacesx are found in running water, especially in waterfalls, clinging
to rocks, loose stones, and stumps of trees which have been stripped of their bark.
Almost all of them inhabit the tropics, the only exception being one species in South
Africa and one in North America. No fossil remains have been found. The number
of existing species hitherto described amounts to 175.

758 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Alliance XLIII.—Viridiflore.

Families: Lettneriacee, Cannabinacee, Dorsteniacee, Artocarpaceee, Ficacee,
Conocephalacece, Moracece, Ulmacece

Annual or perennial herbs, shrubs, and trees. The laminz of the foliage-leaves
veined with pinnate or radiating bundles. Flowers in glomerate, fasciculate, or
spicate cymes; actinomorphic, hermaphrodite, pseudo-hermaphrodite, moncecious, and
dicecious. Perianth composed of 2-8 inconspicuous greenish segments. Gynzeceum
superior, 1-2 carpellary and unilocular. Ovule solitary, pendulous. Stamens as many
or double as many as the perianth-segments; all or those of the outer whorl are

SSS: ZZ

SS = Ye Za

Fig. 428.—“ Living bridge" formed of the aérial roots of the India-rubber and other kinds of Figs in Sikkim-Himalaya.
(After Hooker.)

inserted opposite the segments of the perianth. The pollen in dusty. The fruit is
a one-seeded achene or a drupe. The cotyledons of the embryo are not thickened.
The Ulmacew and Cannabinacex contain watery juices; the plants of the other
families produce milky juice in greater or smaller quantity. The milky juice of the
Indian Ficus elastica is used in the manufacture of caoutchoue, that of the South
American Cow-tree (Galactodendron utile) as an article of diet. The milky juice of
the Upas-tree (Antiaris toxicaria), native to Java, contains poisonous substances.
In the Hop (Humulus Lwpulus) and in the Hemp (Cannabis sativa) bitter and

ANGIOSPERMA, DICOTYLEDONES. 759

i
i H

/

a
=

EZS

Fig. 429,—Amentales.

! Birch (Betula alba) shoot with male and female catkins (the former at the apex). 2 Ripe female catkin of same. 8 Winged
nut of same. 4 Subtending scale of fruit of same. 5 Shoot of Hornbeam (Carpinus Betulus) with male and female catkins
(atter to right). 6 Scale of female catkin with flowers of same. 7 Scale from male catkin with stamens. 8 Scale of female
catkin with ripe fruit. 8, 4, 6, 7 enlarged; the rest nat. size.

760 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

aromatic substances (lupulin and hashish) are produced in special cells and groups of
cells, The curious tabular and columnar roots of the Ficacew have been described
in detail and illustrated in vol. i. pp. 7 55-757. Here is represented a Ficus (fig. 428)
with aérial roots, which Hooker saw used by the natives in the Himalaya as bridges.
“The property of the fig-roots, which inosculate and form natural grafts, is taken
advantage of in bridging streams, and in constructing what are called ‘living bridges’
of the most picturesque forms.” The axis of the inflorescence is thickened in many
cases, notably in the Dorsteniacex, Artocarpacez, Ficaces, Conocephalacese, and

gills

Fig. 480.—The Oak (Quercus sessilijlora).

4 Cluster of female flowers. 2 Single female flower. % Longitudinal section of a female flower showing the ovary with ovules,
small alee and the young cup orcupule. 4 Three male flowers. 5 Cluster of nuts (acorns) with their cupules. & The
seed, 7 Longitudinal section of seed. 8% Transverse section of seed. 1, 2, 3, 4 enlarged; rest nat. size.

Moracee; sometimes it is discoid, and sometimes hollowed out into the shape of an
urn (see p. 157). It also enters into the structure of certain fleshy succulent collec-
tive fruits, which afford such an important article of food in hot countries, viz. the figs
of Ficus, and the Bread-fruit of Artocarpus incisa. Sometimes the perianth also
takes part in the formation of the fruit, as, for instance, in the Mulberry (Morus),
where it is converted into a fleshy envelope inclosing the fruit. On the other hand,
in several other Viridifloree the perianth is almost completely suppressed. In
Dorsteniaceze and Moracee the stamen-filaments are inflexed in the bud, and spring
up after the perianth has opened, scattering the pollen-dust in the air (see fig. 229
P. 187). The filaments are straight in the flowers of the other families. The snaiego
is curved in most cases. There is either a very small quantity of endosperm or none
at all. The Viridifloree are found in all parts of the world. The Ulmacew extend

ANGIOSPERM#, DICOTYLEDONES. 761

Fig. 431.—The Beech (Fagus sylvatica).

762 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

beyond 66° north latitude and 36° south latitude. Representatives of Viridifloree
are most abundant in the tropics. Fossil remains occur in the deposits of the
Mesozoic and Tertiary Periods. The presence of leaves of a Bread-fruit tree (Arto-
carpus Dicksoni) in Greenland chalk, and of quantities of remains of Ulmacese
(Celtis, Zelkova, Ulmus) in the Miocene strata, are points of special interest. The
number of species ascertained to exist at the present day is about 1000.

Alliance XLIV.—Amentales.

Families: Betulacew, Corylacee, Cupuliferce, Juglandacee, Myricacece, Caswarinen,
Salicacec.

Are all large shrubs and forest trees, forming a very conspicuous feature in the
landscape in temperate climates. The flowers are unisexual and arranged in
catkins or heads. Pollination is by wind, and, in the majority of cases, a perianth
is wanting. In the Cupulifere, in which it is present, it is inconspicuous and con-
solidated with the ovary. The group is an exceedingly interesting one, owing to
the recent discovery of several instances of chalazogamic fertilization within its
limits; of this, full details were given at p. 413. In this alliance are included such
familiar trees as the Birch (Betula, figs. 4291234), Alder (Alnus, p. 135), Hazel
(Corylus, p. 147), Hornbeam (Carpinus, p. 483 and figs. 4295%78), Oak (Quercus,
p. 298 and fig. 430), Beech (Fagus, fig. 431), Chestnut (Castanea, p. 445), Walnut
(Juglans), Sweet-gale (Myrica), Casuarina, and the Willow (Salia, pp. 299 and 424)
and Poplar (Populus). Between 500 and 600 species have been distinguished.
Members of this alliance date far back amongst the secondary rocks, and they
are supposed by many to represent a primitive group of Angiosperms.

Alliance XLV.—Balanophorales.

Families: Hydnoraceee, Sarcophytaceee, Cynomoriacece, Balanophoracee,
Scybaliacece.

Plants destitute of chlorophyll, parasitic on the roots of green-leaved woody
plants, with tuberous, cylindrical, or angular stems with flowering lateral branches.
The flowering axes are thickened and fleshy; the flowers hermaphrodite or pseudo-
hermaphrodite, moncecious or dicecious. Perianth of 2-8 segments, sometimes
transformed into a cup on the top of the ovary, or absent and replaced by scaly
bracteoles and hairs. Gynzceum 1-3 carpellary; ovary inferior, unilocular, styles
either absent or 1-2 in number, filiform, and terminating in small stigmas. Stamens
1-60 inserted below the limb of the perianth. Fruit a kind of berry, nut, or drupe.
The embryo is very small, has no cotyledons, and is imbedded at the top of a fleshy,
oily endosperm.

For a description of the suckers and scale-leaves, see vol. i. pp. 186-198. The
flowers of Hydnoracee are solitary; those of Balanophoracez, Cynomoriaces, and
Scybaliacez are crowded in large numbers on unbranched clavately-thickened axes,

ANGIOSPERM#, DICOTYLEDONES, 763:

and those of Sarcophytacess on branched clavate axes. In Hydnoracee the cavity
of the ovary is occupied by numerous ridges which project from the walls and bear
the ovules; in Sarcophytacew, Scybaliaces, Cynomoriacer, and Balanophoracez the
placentation is parietal, and the number of the seeds is 3 in Sarcophytacem, 2 in
Seybaliacesw, 1-3 in Cynomoriacew, and 1 in Balanophoracew. In Hydnoracex and
Sarcophytaces there is no style, and the free upper extremities of the masses of
tissue which bear the ovules act as stigmas. The Cynomoriaceew and Balanophoracez
have one, and the Scybaliacez two, filiform styles with small papillose stigmas. In
Hydnoraces the stamens are inserted between the lobes of the perianth, and form a
fleshy ring; in the other families they stand in front of the segments of the perianth;
in the Balanophoracew the filaments are connate. Most of the Balanophoracez live
in the tropical parts of Asia and America; a few species inhabit South Africa and
New Holland. Cynomoriwm coccinewm, the only species of the Cynomoriacex,
grows in the Mediterranean area and in Western Asia (see vol. i. p. 197, fig. 42).
Fossil remains are not known. The number of extant species hitherto discovered is
about 45.

Sub-Class IIL—MONOPETALZ.

Alliance XLVI.—Caprifoliales.
Families: Rubiacee, Caprifoliaceee

Annual and perennial herbs, shrubs, and trees. The foliage-leaves are opposite,
stipules are present at their bases (see fig. 4321). The flowers are in cymes,
actinomorphic and zygomorphic, hermaphrodite and pseudo-hermaphrodite. The
floral-leaves are differentiated into calyx and corolla. The calyx is composed of
one 2-6-sepalous whorl. The calyx-tube clothes the inferior ovary, whilst the limb
consists of small green teeth. The corolla is a whorl of 3-6 connate petals (see fig.
432%). The gyneceum is composed of 2-5 connate carpels; ovary inferior, 2-5
locular. The placentas are axile. The androecium is a whorl of 3-6 stamens,
adnate to the corolla-tube. The pollen is either adhesive or powdery (see p. 265).
The fruit is a berry, drupe, schizocarp, or capsule. The seed contains endosperm.

Most of the Rubiaceze are herbaceous, whilst the species of the other families
are mostly shrubby and arboreal plants. In the roots of several Rubiacewe (e.g.
Rubia tinctorum and Galium boreale) there is a red colouring matter (madder-
red); the Coffeaceze and Cinchonacesx contain alkaloids (caffeine, quinine, &c.); the
sweet-scented Woodruff (Asperula odorata), the herb used to make the German
May-wine, is famous for the kumarin it contains. No laticiferous tubes or latex,
however, are contained in the tissues of any species belonging to this alliance.
The foliage-leaves are always opposite and in pairs, which are at right angles to
one another; the venation of the lamine is pinnate. In the Stellatz section of
Rubiacese the stipules are of the same size, colour, and form as the laminz of the
opposite leaves to which they belong, and are inserted between them. The conse-
quence is that at each node there is a whorl of leaf-structures arranged in the form

764 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

of a star. In the Cinchonacee and Coffeacee, the stipules are squamiform, and
sometimes lacerated (see fig. 4321). In the Caprifoliacez they are either very small
and in the form of stalked glands, or else they are adnate to the base of the petiole,
and have the appearance of being narrow sessile segments of the leaf. The cymose
inflorescences may be contracted into glomerules and fascicles, in which case each
is surrounded by an envelope of bracts, as, for instance, in the Ipecacuanha plant
(Cephaélis Ipecacuanha; see fig. 4327), or they may form pyramidal panicles, as in
the Cinchona, or, lastly, they may be flat cymes, as in the Elders (Sambucus nigra

Fig. 432,—Caprifoliales: Cephaélis Ipecacuanna (Family Rubiacez).

1 Entire Plant. 2Inflorescence. 8 Single flower. 1 reduced; 8 and 8 magnified. (After Baillon.)

and S. Hbulus). In the Caprifoliacese, especially in the genera Linnea and
Lonicera, two-flowered cymes also occur, and in several species of the genus
Lonicera, the ovaries of the two flowers in each cyme are connate. The flowers of
several Caprifoliacese (Linnea, Lonicera, &e.) are zygomorphic, whereas the other
members have actinomorphic flowers. In the Stellate the fruit is a schizocarp which
breaks up into two mericarps; in Cinchonacew, it is a capsule which dehisces from
the base upwards (see p. 481, fig. 325"). In Coffeacer, Sambucacew, and the genus
Linnea, the fruit is a drupe, and in Gardenies and some of the Caprifoliacez, a
berry. The baccate fruits of several species of the genus Lonicera (L. alpigena
L. coerulea, &c.), coalesce to form a collective fruit. Each chamber in the fruit of

ANGIOSPERM, DICOTYLEDONES 765

Rubiacex, Coffeacess, Sambucacesw, and of the genus Linnea, contains one seed,
in most Caprifoliaces, as in the genus Lonicera, several, and in the Cinchonacee,
many seeds. The seeds of Cinchonacew are winged (see p. 423, fig. 318").

The Caprifoliales are distributed over all parts of the earth. The Coffeaces and
Cinchonacese are chiefly tropical plants, whilst the Rubiaces, Sambucacex, and
Caprifoliacess belong principally to the North Temperate Zone. The Cinchona is
found wild only in the Cordilleras in South America (from 10° north lat. to 22°
south lat.). Tropical Africa is supposed to be the original home of the Coffee-tree
(Coffea Arabica). Linnea borealis, a plant named after the Swedish botanist,
Linneus, is scattered over the Alps, in the low-lying part of Germany adjoining
the Baltic, and in Scandinavia. Several species of the genus Galiwm, of the family
Rubiacez, belong to the flora of the extreme North and of high mountains. Fossil
remains have been preserved in the deposits of the Mesozoic and Tertiary Periods.
The number of extant species discovered up to the present time is about 4800.

Alliance XLVII.—Asterales.

Families: Valerianacee, Dipsacece, Calyceracee, Brunoniacee, Composite.

Annual and perennial herbs, shrubs, and trees. Foliage-leaves extremely various
in form but always destitute of stipules. Inflorescence a cyme or a capitulum.
Flowers actinomorphic and zygomorphic, hermaphrodite, pseudo-hermaphrodite,
monecious, and dicecious. Floral-leaves differentiated into calyx and corolla.
Calyx of 2-5 sepals; the limb, which crowns the inferior ovary, is in the form of
a pappus, bristles, scales, teeth, callosities, or membranous borders, and is destitute
of chlorophyll. The corolla is composed of 4-5 connate petals. The gyneceum
consists of 2-3 connate carpels. The ovary is inferior and contains only one devel-
oped loculus with a single ovule in it (see p. 73, fig. 207°). The andrcecium consists
of 1-5.stamens. The filiform filaments are adnate at the base to the corolla-tube.
The fruit is a unilocular, one-seeded achene.

The plants belonging to this alliance exhibit for the most part herbaceous growth,
but some Composite are shrubby (e.g. Baccharis), and some arboreal (e.g. Vanillos-
mopsis, Lychnophora). Several Valerianaceze and Composite, eg. the Dahlia
and Jerusalem Artichoke (Dahlia variabilis and Helianthus tuberosus), are distin-
guished by underground tuberous structures. The inflorescence in Valerianaces is a
much-branched cyme (see p. 305, fig. 289"). In Dipsacez also the arrangement of
the flowers is cymose, but the cymes are usually grouped together in capitula (see
p. 121, fig. 2255). In some genera, such as Morina, they are arranged in opposite
fascicles in the same manner as in Labiate. The flowers of Composite are situated
at the extremity of a thickened axis which is conical, hemispherical, or flat, and
compressed, as the case may be; they are spirally arranged and are grouped to-
gether in capitula (see p. 242). In many cases they spring from the axils of scales
(“pales”), or else their place of origin is surrounded by bristles. Not infrequently
they spring from little depressions, and then the axis is seen to be pitted when the

766 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

flowers have fallen off. The number of flowers in a capitulum varies greatly. In
many species several hundreds of flowers (florets) are crowded together, in Adeno-
styles and Ewpatorium (see p. 820, fig. 294+) there are only a few flowers in each
capitulum, and in Echinops it is limited to a single one. The capitulum is sur-
rounded by an involuere of bracts crowded together. The form of these involucral
leaves exhibits extreme variety. In Thistles their apices are transformed into
prickles, in the species of the genus Xeranthemum, Helichrysum, &., they are like
paper or parchment, dry, and distinguished by white, yellow, violet, and red colours.
They preserve these characteristics unchanged even when dried, and can therefore
be made up into bouquets and wreaths which do not fade. These composite flowers,
which are known as “immortelles”, are everywhere used as symbols of immortality
and as memorial tokens. The Cape is exceptionally rich in Everlasting Flowers;
among the species found there is Helichrysum eximium. The Edelweiss (Gnaphalium
Leontopodiwm, see vol. i. p. 315, fig. 76) may also be looked upon as an immortelle,
although here the bracts are not themselves dry and membranous, but are only
covered with a dry, white felt of hairs. In many species the capitula are themselves
grouped in capitula or glomerules. One of the most striking instances of this is
afforded by the species of the genus Haastia, which are shown on p. 188. In the
genus Echinops a large number of one-flowered capitula are grouped together in
spherical heads, usually of a steel-blue colour. The capitula often look like single
flowers, and in former times they were looked upon by botanists as compound
flowers (flores composite), whence the name of Composite. In many species, e.g. the
Sun-flower (Helianthus annuus), the capitula attain to a diameter of 40 centi-
metres. In the actinomorphic corollas a tube and a bell-shaped 5-partite limb may
be distinguished (see p. 360, figs. 302123). The zygomorphic flowers are either two-
lipped, the upper lip being composed of one or two petals, and the under lip of four
or three petals, or else ligulate, in which case the tube is greatly abbreviated and
the free end of the ligule usually exhibits five segments or teeth (see p. 121, fig. 2224,
and p. 236, fig. 261%). In Valerianacez the corolla is usually produced on one side
into a kind of sac, which in the genus Valeriana is short and blunt (see p. 289,
fig. 283%), and in the genus Centranthus is in the form of a long, slender, pointed
spur (see p. 240, fig. 263°, and p. 305, figs. 289%). In the capitula of Composite the
flowers with tubular, ligulate, and bilabiate corollas respectively are grouped to-
gether in a great variety of ways. It is not common for all the flowers of a capitu-
lum to have tubular flowers, but that is sometimes the case (eg. Hupatorium,
p. 320, fig. 2947); much more frequently all the flowers in a capitulum have ligulate
corollas (e.g. Hieraciwm, p. 112, fig. 2225), and in the majority of instances the
flowers in the middle of the capitulum are furnished with tubular corollas, and
those near the periphery with ligulate or bilabiate corollas (see p. 360, fig. 302 1).
The distribution of the sexes has been dealt with on pp. 295-297, and pp. 318-321.
In the Composite the anthers of the five stamens are united into a tube. The
anthers are not connate in the other families. In Dipsacese the andrcecium consists
usually of four stamens, and in Valerianaces usually of three stamens (see p. 289,

ANGIOSPERMAE, DICOTYLEDONES, 767

fig. 283°); the genera Morina and Fedia have two stamens in each flower, whilst
the genus Centranthus (Red Valerian) has only one (see p. 240, fig. 2637). For a
description of the pollen of Composite see p. 99. The gyneceum in Valerianacex is
composed of three carpels, and the ovary is originally 3-locular, but two of the
carpels are abortive, and only the third loculus is completely developed. In the
other families the ovary is unilocular from the first. The ovule and the seed result-
ing from its development is pendulous (see p. 178, fig. 249, and p. 240, fig. 263 ”) in
Dipsacee and Valerianacesw, basal (see p. 73, fig. 2075) in Composite. In most
cases the calyx remains adnate to the mature fruit and assumes the form of a crown
of hairs or bristles, which is termed a “pappus” (see p. 432), or else constitutes a
membranous limb. In a later chapter we shall deal with the significance of these
structures. In the Dipsacez the fruit is surrounded by a saccate involucre called
an involucel. The alliance is distributed over all parts of the earth; its members
flourish both in the tropics and in the arctic regions, and are met with on the sea-
shore and by the side of glaciers, in bogs and on arid ground, in shady woods and on
sandy steppes. The greatest number are natives of the North Temperate Zone. In
the Himalayas several Composites occur at an elevation of 4500 metres. Fossil
remains have been found in small quantities in the deposits of the Mesozoic and
Tertiary Periods. The number of extant species identified up to the present time is .
about 10,700.

Alliance XLVIII—Campanales,
Families: Campanulacew, Lobeliacece, Stylidiacee, Goodeniacee.

Annual and perennial herbs with entire exstipulate foliage-leaves arranged
spirally. Flowers in capitula or racemes, or else solitary; actinomorphic or zygo-
morphic, hermaphrodite or pseudo-hermaphrodite. Floral-leaves differentiated into
calyx and corolla, Calyx of one whorl of 3-8 sepals, corolla of one whorl of
3-8 petals. The calyx-tube clothes the inferior ovary, and the calyx-limb is in
the form of 3-8 comparatively large, green segments which crown the top of the
ovary. The petals are joined. The gynzceum is composed of 2-5 connate carpels;
the ovary is inferior and 2-5 locular. The ovules are numerous, and are. borne on
axile placentas. The andrcecium consists of one whorl of 3-8 stamens, which are
attached to the bases of the petals. The filaments are free; in the young flower
the anthers are in close contact, forming a tube surrounding the style (see p. 360,
figs. 3021911), Sometimes they are connate, and in that case the tube persists even
when the flower begins to fade. The pollen is adhesive. The fruit is a capsule
(see fig. 3401, p. 448). ;

All the Campanales have laticiferous tubes running through them, and in
several species the leaves and stems are copiously supplied with latex. The flowers
are actinomorphic in Campanulacexw, zygomorphic in the other families. In the
Stylidiacez, only two of the stamens develop pollen capable of effecting fertilization,
whilst three stamens are abortive; in the other families all the stamens produce

768 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

pollen, which ripens effectually. The Campanales are distributed over all quarters
of the globe. The Campanulacee are mostly natives of the North Temperate
Zone, the Lobeliacew of the South Temperate Zone and the Tropics. Some
Campanulacex are also found amongst the flora of the Arctic regions, and of high
mountains. The Stylidiacew and Goodeniacee are confined to Australia. No
fossil remains have been discovered. The number of identified species now living
is about 1300.
Alliance XLIX.—Hricales.

Families: Diapensiacew, Pyrolaceew, Monotropacee, Lennoacece, Arbutacee,
Rhodoracee, Ericacee, Epacridacee, Empetracee, Ebenaceee, Sapotacece.

Perennial herbs, shrubs, and trees. Flowers actinomorphic and zygomorphic,
hermaphrodite, pseudo-hermaphrodite, moncecious, and dicecious. The floral-leaves
arranged in two 3-5 partite whorls. The lower whorl constitutes a calyx, the
upper a corolla. The petals are free in Pyrolaceze and Monotropacee; in the other
families they are coherent, at any rate at the base. The gynzeceum is composed of
3-10 carpels; the ovary is superior, and 3-10 celled. The ovules arise from an
axile placenta. The andrcecium is composed of one or more whorls of 4-5 stamens
each. In many cases some of the stamens are metamorphosed into gland-like
structures. The fruit is a capsule, berry or drupe. The embryo is erect, and
imbedded in the fleshy endosperm.

The Diapensiacese and Pyrolacez (see figs. 277%* p. 273), are perennial herba-
ceous, or suffruticose plants, which grow in black humus, and have stiff, evergreen
foliage-leaves; the Monotropacee and Lennoacew are parasites or saprophytes
(see vol. i. p. 252), and are destitute of chlorophyll. The Arbutacez, Rhodoracee,
Ericacex, Epacridacee, and Empetracee are, for the most part, dwarf shrubs; only a
few are trees. Erica arborea, one of the Mediterranean Flora, when able to grow
without hindrance, attains the height of 8 metres. The branches of Ericacez, Epa-
cridacee, Empetracex,and of Lowseleuriaor Azalea procumbens, one of the Rhodoracee,
are thickly covered with stiff, rolled leaves (see vol. i. p. 8037). The species of the
genus Rhododendron have flat foliage-leaves (see Plate X.), as have also the
Arbutacez (see fig. 433"). The leaves of Arctostaphylos alpina, Azalea Pontica,
and A. mollis are green in the summer only, whilst most of the Arbutacese and
Rhodoracez have flat, evergreen foliage. The Ebenacee and Sapotacee exhibit,
in a large proportion of their species, arboreal growth and leathery foliage-leaves.
All the Ericales are distinguished for their solid timber. Some of the Rhodoracew
have zygomorphic flowers; the rest of the Ericales have actinomorphic flowers. In
Loiselewrva, and in the Empetraces and Epacridacex, the androecium is composed
of one whorl; in the others it consists of two or more whorls. The anthers of
Arbutacee and of many Ericaceze possess two peculiar horn-like appendages (see
figs. 433° and 4334, and figs. 2161.11, p, 91). In Epacridacese the anthers are
unilocular, and dehisce longitudinally; in Ericacese, Arbutacew, Rhodoraces, and
Pyrolace they usually open by terminal chinks or pores (see p. 91, figs. 216 & % 10 11,12),

ANGIOSPERMH&, DICOTYLEDONES, 769

The pollen is dusty in Ericacezx, but adhesive in most other cases, The pollen-cells
are united in fours in Ericacex, Rhodoracex, and Pyrolacex, and in the Rhodoracez
these groups are connected by tough threads (see figs. 219%34 p. 101). The fruit
is capsular in Diapensiacex, Pyrolaces, Monotropacess, Rhodoracesw, Ericacez, and
Epacridacee, and baccate in Arbutaces, Empetracese, Sapotacess, and Ebenacea.
In the Lennoaces the fruit resolves itself into 10-28 one-seeded portions. The
‘Ericales are distributed over the whole world; the Ebenacez and Sapotacez live
‘chiefly in the tropics; the Lennoacew are confined to the southern half of North
America, and the Epacridacee to Australia. The species of Ericacese are most
abundant at the Cape. Most of the species of the genus Rhododendron inhabit

Fig. 483.—Ericales: Arbutus Unedo of the family Arbutacez.

1 Flowering branch. 2 Three flowers magnified. § Longitudinal section through a flower. # Flower from which the corolla
has been removed. 5 Papillose berry. 2,3 and +4 magnified. (After Baillon.)

the mountains of Central Asia, e.g. the Himalayas. The genus Kalmia belongs to
the mountains of North America, The Diapensiacez live in the arctic regions, as
also do several Ericacew. Loiselewria or Azalea procumbens is widely distributed in
the arctic regions, and also occurs in exactly the same form on the mountains of
Central and Southern Europe; in the Central Alps it attains its maximum elevation
of 2700 metres above the sea-level. Most of the Ericales grow sociably on rocky
declivities in mountainous districts, and on sandy soil in plains. Many only
flourish on moorland, or when rooted in a deep layer of humus, and these play an
important part in the formation of peat. Fossil remains are found in the deposits
of the Mesozoic, Tertiary, and Diluvial periods. The number of extant species
known is about 2300.

Vou, II. 99

770 THE SUBDIVISIONS OF THE VEGETABLE. KINGDOM.

Alliance L.—Vacciniales.

Families: Vacciniacew, Oxycoccacec.

Woody plants, presenting all gradations in form, from that of delicate dwarf
shrubs lying upon the ground to that of stately trees. The foliage-leaves arranged
spirally, exstipulate. Flowers in racemes and fascicles, or solitary; actinomorphic,
hermaphrodite. Floral-leaves differentiated into calyx and corolla. The calyx is
composed of a whorl of 4-6 sepals. The calyx-tube clothes the inferior ovary; the
calyx-limb is in the form of short, green teeth, crowning the top of the ovary,
The corolla consists of a whorl of 4-6 petals; the petals are united or free. The
gynaceum is composed of 4-6 connate carpels. The ovary is inferior and 4-6-
locular. The placentas are axile. A honey-secreting tissue is situated on the
top of the ovary. The andrcecium consists of two whorls with 4-6 stamens in
each. The stamens surround the nectary, and are free from one another and from
the corolla. The members of the outer whorl are opposite the petals. The fruit
is a berry or a drupe. The seed contains a fleshy endosperm.

The Vacciniales have no laticiferous tubes or latex. In Vacciniacez the petals
are united, and the anthers are furnished with horn-shaped appendages, in Oxy-
coccaces the petals are free, and the anthers have no horns. The Vacciniales are
distributed in all quarters of the globe, and in all latitudes. The species which
belong to the Temperate Zones grow in peat-bogs and in the humus of woods and
heaths, the species native to the mountains of tropical regions are, in some cases,
epiphytic on the bark of old trees. Many are of social habit, and cover extensive
tracts of ground. This is the case, for instance, with the various species of the
genus Vacciniwm: the Cow-berry (Vacciniwm Vitis-Idea), the Bilberry (Vac-
cinium Myrtillus), and Vaccinium uliginosum. These species are also found
within the area of the Arctic Flora. Vacciniwm uliginosuwm ranges furthest to the
North, and in Greenland forms with the dwarf Birch (Betula nana) and dwarf
Willows, a low undergrowth which reaches to 73° N. Lat. They clothe the. moun-
tain sides in the Central Alps as far as 2400 metres above the sea-level. Fossil
remains have been found in the deposits of the Mesozoic, Tertiary, and Diluvial
Periods. The number of extant species hitherto recognized amounts to about 350.

Alliance LI.—Primulales.

Families: Primulacee, Plumbaginacee, Myrsinacea.

Annual and perennial herbs, shrubs, and small trees with alternate, opposite, and
verticillate foliage-leaves, Fowers solitary, or in spikes and racemes; actinomorphie,
hermaphrodite or pseudo-hermaphrodite. The floral-leaves are arranged in two
whorls of 4-8 segments each. The lower whorl constitutes a calyx, the upper a
corolla. The petals are coherent. The pistil is superior, 5-carpellary, unilocular.
The ovules are supported in the middle of the ovary on a column of varying length

ANGIOSPERME, DICOTYLEDONES. V1

rising from the bottom of the ovary. The stamens, five in number, are inserted in
front of the petals, and are adnate to them (eprpetalous). The fruit is a unilocular
capsule or drupe, The seeds contain an endosperm, in which the embryo is
embedded.

The ovary is surmounted by a single style in Primulacee and Myrsinacez, by
five styles in Plumbaginaces, The capsules of Primulacese are many-seeded, those
of Plumbaginacew are one-seeded. In the genus Glaua only one floral envelope is
developed. It has the appearance of a perianth, and resembles that of Polygo-
nacew. It is interpreted as being a petaloid calyx. The fact that in Glaua the
stamens occupy the same position in relation to the sepals as the petals do in other
cases warrants our supposing that what is usually designated as the corolla in
Primulaces is only a whorl of stamens with connate petaloid filaments. The
Primulaces are distributed mainly in the temperate zone of the Northern Hemi-
sphere. Most of the species of the genera Primula, Soldanella, and Androsace are
alpine plants. The Alps and the Himalayas are particularly rich in these species.
Androsace glacialis (see fig. 221%) occurs in the Alps in the neighbourhood of
glaciers at a height of 3160 metres above the sea-level. Primula pubescens, a plant
obtained by Clusius in 1582 from the Gschnitzthal in Tyrol, was the original species
from which Auriculas were derived during the fashion for their cultivation which
prevailed in the seventeenth century. The Plumbaginacex are represented by
large numbers of species on the shores of the Mediterranean and in the saline
steppes of the East. The Myrsinacem grow exclusively in the tropics. Fossil
remains of Myrsinace are known amongst the deposits of the Tertiary period.
The number of species now existing is about 1100.

Alliance LIT.—Tubiflore.

Families: Gentianacee, Asclepiadacee, Apocynacee, Loganiaces, Convolvulacee,
Polemoniacce, Hydrophyliacew, Boraginaceew, Nolanacee, Solanaceae,
Scrophulariacew, Lentibulariacee, Bignoniacee, Acanthacew, Gesneracee,
Orobanchacee, Globulariacee, Plantaginacee, Myoporacee, Verbenacece,
Labiate, Oleacec, Jasminacece.

Annual or perennial herbs, shrubs, and trees. Flowers actinomorphic and
zygomorphic, hermaphrodite and pseudo-hermaphrodite. Floral-leaves in two
4-5-partite whorls; the lower whorl in the form of a calyx, the upper in the form
of a corolla. Petals united. Gynzeceum 2- or more celled, ovary superior. The
ovules are developed either on the turned-in margins of the carpels or on an axile
placenta. The andrcecium is composed of a whorl of 2-5 stamens. The fruit is
either a succulent berry, a capsule with various modes of dehiscence, or a drupe.

The Solanacez, Scrophulariaceze, Loganiacee, and Asclepiadacez contain poison-
ous alkaloids, the Gentianaces contain bitter substances, and the Labiatee contain
etherial oils and aromatic substances. The majority of Tubifloree possess green
foliage-leaves. Some Scrophulariaces, e.g. the species of the genus Rehmannia, are

772 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

in the form of switch-shrubs, and several Asclepiadacew, e.g. the species of the genus
Stapelia, have cactiform stems. In these the assimilation of carbon is effected by
the green cortical tissue. The Orobanchacee are parasites destitute of chlorophyll
(see vol. i. p. 183). Amongst Convolvulacez, and more especially amongst Serophu-
lariacese, there are many species which live as parasites and saprophytes, and are
partially deficient in chlorophyll (see vol. i. pp. 171-183). An account has already

Fig. 484.—Acanthacew. pobrne.

Acanthus mollis on the coast of Dalmatia.

been given of the way in which the Lentibulariacez, eg. the species belonging to
the genera Utricularia and Pingwicula, derive a portion of their food from the
bodies of insects which are caught by them (see vol. i. pp. 120, 140). In Gentianacex,
Oleacess, Apocynacer, Asclepiadacess, Convolvulacez, and many Boraginacezs and
Solanacez the corolla is actinomorphic. The Labiate, Scrophulariacex, Verbenacex,
Acanthacee, Lentibulariacex, and some genera of Boraginacee and Solanacew bear
distinctly zygomorphic flowers. In the Ash genus (Fraainus), which belongs to the
family of Oleacez, the corolla is often entirely suppressed. Most Labiatz have four

ANGIOSPERMA, DICOTYLEDONES, 773

didynamous stamens, but some of them, eg. those of the genus Salvia (see fig. 271,
p. 262), have two stamens, as have also the species of the genus Veronica (see fig. 257,
p. 226) of the family Scrophulariacew, and the majority of the Jasminacew and
Oleaces (see fig. 283°). Most of the Tubiflore possess five stamens. The curious
modification of the androecium of Asclepiadacew has been fully described on p. 257,

Fig. 435.—Ranunculacee.

' Helleborus niger (reduced 3). 2 Muyosurus minimus, complete plant with fiowers and flower-buds (nat. size). 8A single
flower of Myosurus (magnified).

et seq. In the Apocynacee the two opposite carpels are separate at the base and
connate at the upper end only. The fruit of Labiatz and Boraginacez resolves
“itself when it is ripe into four one-seeded nutlets. The seeds of Apocynacee and
Asclepiadacez are furnished with a plume of hairs. In most of the Tubiflore the
base of the pistil is partially or completely surrounded by swollen tissue which

774 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

secretes honey. The Tubiflore are distributed in every quarter of the globe. Several
families, such as the Loganiacee and Bignoniacez, are confined to tropical and sub-
tropical regions. The Acanthacez also chiefly inhabit the warmer parts of the
earth, The genus Acanthus grows particularly in the region of the Mediterranean
Flora. The leaves of several species of Acanthus, e.g. Acanthus spinosissimus (see
vol, i, fig. 116, p. 437) and Acanthus mollis (see fig. 434), frequently served the
Greek and Roman sculptors as patterns for their ornaments, The genus Stapelia,
of the family Asclepiadacez, is confined to the Cape; the Labiate are most abundantly
represented in the Mediterranean Flora; the Gentianacew and Scrophulariacese
inhabit mountainous regions of the Old and the New World in large numbers of
different forms, and several species of the genera Gentiana, Veronica, Euphrasia,
and Pedicularis thrive best in proximity to glaciers both in mountain districts and
in the arctic regions, Fossil remains occur in the strata of the Tertiary period.
The number of species now living which have been identified up to the present
time is about 16,500.

Class III—POLYPETALA,
Alliance LITI.—Ranales,

Families: Ranunculacee, Dilleniacee, Calycanthacee, Magnoliacew, Anonacec,
Menispermacee, Berberidacew, Lardizabalacee, Nympheacee.

Stamens rarely definite. Carpels, free or immersed in the receptacle, very rarely
connate. Embryo minute, embedded in a fleshy endosperm. In the Ranunculaces
the petals are not infrequently modified into honey-glands, and the sepals petalline.
The carpels are free from one another, and sometimes indefinite and spirally ar-
ranged, sometimes definite and whorled. In Calycanthus, the parts of the flowers
are inserted in a continuous spiral upon a hollow receptacle, and pass gradually the
one into the other. In Berberidaces, the anthers open by means of valves. The
Nympheacez include marsh and water plants (e.g. Nymphaea, Ni uphar, Nelumbium,
of. fig. 436, Victoria Regia, Plate XI.). In several of these the carpels are united
together into a large ovary with shield-like stigmatic disc. In Nelwmbium (of.
fig. 334, p. 440), the carpels are borne in distinct sockets. The fruit in the alliance
is very varied, and includes achenes, follicles, berries. Fossil remains occur in the
Tertiary Strata. Total number of living species about 3000

Alliance LIV.—Parietales.

Families: Sarraceniacew, Papaveracew, Fumariacerr, Crucifere, Capparidacee,
Moringacece, Resedacece, Cistinece, Violaceew, Bixacec.

Annual and perennial herbs, shrubs, and trees,- Flowers solitary or in spikes,
umbels, racemes, and racemose cymes; actinomorphic and zygomorphic, herma-
phrodite and pseudo-hermaphrodite. Floral-leaves differentiated ‘into calyx and
corolla; the calyx composed of a 2-5-partite whorl, the corolla of two 2-partite

ANGIOSPERMA, DICOTYLEDONES, 775.

whorls or one 5-partite whorl. Petals free. Gynaceum composed of 2, 3, or several
carpels joined together to form a unilocular (or spuriously bilocular), free, superior
ovary. Ovules attached to the interior walls of the carpels on ridges, or springing
directly from the walls of the ovary (see fig. 4377). The andrcecium is composed
of either one whorl or many whorls of 2-5 stamens; the stamens are free, and
generally of equal length, and are not joined together or to the corolla (see fig. 243,
p. 168). The fruit, in most cases, is a many-seeded capsule (see fig. 4377); in the
genus Fumaria it is a small one-seeded drupe (see figs. 83221 and 322% p. 427),

In the Capparidaces, it is borne on a long stalk. The Resedacex are interesting,
in that in many of them the ovary is open from the beginning, the stigmatic tissue
being formed by the swollen lips. The Cruciferes form a large and. important
family of over 200 genera. For systematic purposes they are divided into the
following tribes:—Pleurorhizew, Notorhizezx, Orthoploces, Spirolobeze, and Diploco-
lobee. Annual or perennial herbs and suffrutices with the foliage-leaves in spirals,
venation pinnate. Flowers in racemes, hermaphrodite, pseudo - hermaphrodite,
actinomorphic and zygomorphic. Floral-leaves differentiated into calyx and corolla,
each of which is composed of two 2-merous whorls. Petals free. Ovary free,
superior. The carpels spring from below the end of the conical receptacle, and are
of two kinds: the two lower carpels bear no ovules, but form valves, whilst the two

gens a 4 if MVETATY)
i. *, * . . . . bs uf .:
Fig, 486.—Nelumbiwum speciosum, the Indian Lotus, growing in a marsh, near Pekin (from a photograph). pause.

776. THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

upper are transformed into ribs and form a framework to which the valves are

applied. The two superior carpels are separated by a thin membrane, and bear the

ovules in two rows (see p. 75). The andrcecium is composed of two short and four ,

long stamens (see p. 292, fig. 284°). The pollen is adhesive. The fruit is a siliqua

(see p. 75 and p. 431, fig. 325116), The seeds have no endosperm. The embryo
is curved. The cotyledons and also the foliage-leaves and.
roots of most Crucifere contain pungent and oily substances,
particularly Oil of Mustard, as is well known in the cases.
of the Mustard-plant, Water-cress, Garden-cress, Radish, and
Horse-radish.

The Cruciferze are distributed over the Northern Hemi-
sphere. They occur in greatest variety in the steppe-dis-
tricts of the Old World. The Mediterranean, Arctic, and
Alpine floras also include large numbers of these plants.
“Amongst those Phanerogams which survive at the very
confines of vegetation in the Arctic regions, and on moun-

’ tains, are to be reckoned several Crucifere. No fossil
remains are known. —

The Sarraceniacese are marsh- and water-plants, and
their leaves are adapted to the capture of insects (see vol. i.
p. 148 et seg.), whilst the rest of the Parietales grow chiefly
on rocky or sandy ground. The Parietales are distributed
over the warm and temperate parts of the Old and the New
World; the Cistacew belong especially to the flora of the
Mediterranean. The only known instance of fossil remains
is the fruit of a Poppy which was found in a deposit of
the Tertiary Period. The number of extant species hitherto
identified is about 3000.

Fig. 437.—Parietales.

Alliance LV.—Malvales.
1 Bixa Orellana (Bixacez). Lon-
gitudinal section through a
flower-bud which is about to
open. 2 Argemone Mexicana

Families: Malvacee, Sterculiacee, Tiliacee.

(Papaveracez). Longitudinal Flowers actinomorphic, parts in whorls of 5. Sepals
section through the ovary, ‘é .
(Magnified.) free or connate, often valvate in bud. Stamens various,

often united. Carpels 8 to indefinite, united. Placentation
axile; seeds with endosperm. The Malvacee often possess an epi-calyx; fruit
usually splitting into 1-seeded mericarps. They include the Mallows (Malva),
Cotton-plants (Gossypiwm), Hollyhock (Althea), &e. The Tiliacee are represented
by the Linden (Tilia), and the Sterculiacess include Theobroma Cacao, from which
chocolate is derived.
There are nearly 200 species in this alliance.

_ANGIOSPERMA, DICOTYLEDONES. 177

Alliance LVI.—Disciflorm.

Families: Linacew, Erythrowylacece, Oxalidacee, Humiriacee, Malpighiacee, Zygo-
phyllacee, Geraniacew, Balsaminee, Tropeolacece, Rutacee, Auriantiacee,
Diosmacece, Zanthoaylaceee, Simarubacew, Ochnacece, Burseracece, Meliacecr,
Ilicinew, Celastrinece, Rhamnacece, Ampelidec, Sapindacece, Acerinee,
Hippocastanece, Sabiacece, Terebinthacece.

Annual and perennial herbs, shrubs, and trees, with simple and compound
foliage-leaves. Flowers actinomorphic and zygomorphic, hermaphrodite, pseudo-
hermaphrodite, moncecious and dicecious; arranged in varying types of inflores-
cence. Floral-leaves in two 45-merous whorls; the lower whorl a calyx, the upper
a corolla. The gyneceumtis composed of a whorl of carpels- borne on a swollen
disc. Ovary superior. Each carpel has a separate loculus. In Aurantiaceew and
Ampelides the carpels are completely united so as to form a single pistil; in
Rutaces: and Zygophyllacew they are united at the base and form a lobed ovary,
whilst in Zanthoxylacee, Ochnacex, and Simarubaces, they are quite separate (see
fig. 438°). In Terebinthacez only one carpel is developed, but there are usually
traces of suppressed carpels close to it. The ovules are in the inner angles of the
loculi; in Aurantiacese, Rutacee, and Zygophyllacee their number exceeds two in
each loculus, in the other families it is only 1-2. The stamens are arranged in 1-2
whorls, and number 4-5 in each whorl; they spring from the edge or from the
surface of the floral receptacle, which is swollen and forms a ring round the ovary;
their place of origin is always lower than the base of the ovary (see figs. 438 2:57),
The pollen is adhesive. The fruit contains either few seeds or a single compara-
tively large seed.

The Discifloree are in most instances woody plants, containing etherial oils and
aromatic, resinous substances like turpentine. Amongst the Malpighiaces, Celas-
trinee, and Ampelides are many lianes. The foliage-leaves are undivided in
Erythroxylacez and Celastrinee (see fig. 4381), lobed in most Aceracee and
Ampelidex, and variously segmented and compounded in the other families (see
fig. 438°), The petals are usually small, and of a greenish-yellow colour. The
filaments in Melianthacew and Aurantiacez are connate all together, or in groups.
The fruits are extremely various. In Staphyleaceze and Diosmacee they are
follicles; in Celastracee and Rutaces, capsules (see fig. 825°, p. 431); in Ly go-
phyllacez, Aceracez, and Malpighiacez, schizocarps; in the Tree of Heaven, of the
family Simarubacee, winged achenes (samaras, see fig. 323’, p. 428); and in
Ampelidee and Aurantiaces, berries. The Disciflore are distributed over the
whole earth. The majority belong to the tropics, and several, eg. Burseraces,
Ochnacez, and Malpighiacex are exclusively tropical. The Diosmacez are confined
to South Africa, the Rutacesw to the districts of the Mediterranean and the Black
Sea. Comparatively few species occur in the Northern Temperate Zone, or in
corresponding situations on mountains. The Mountain Maple covers about the

178: THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

Fig. 438. —Discifors.

1 Euonymus Europeus (Family Celastrinen), flowering branch. 2 ‘Longitudinal section through a flower, 8 Quassia amara-
(Family Simarubacew), flowering branch. 4 Gyneeceum: and floral receptacle. 6 Ochna (Family Ochnacer), receptacle,
gyneceum, and onestamen. 6 Fruit of same, 7 sia segs section trong the flower of the Tree of Hear. ‘en (Ailanthus,
family Simarubacex), (Pattly after Baillin.) : ae 4 Oe ee M8

ANGIOSPERME, DICOTYLEDONES, 779

same ground as the Beech, and, in the Central Alps, even extends beyond the upper
limit of the Beech. Fossil remains are found in the Mesozoic and Tertiary strata,
The number of known species now living is about 9000.

Alliance LVII.—Crateranthey,

Families: Leguminose, Rosacece, Saxifragacee, Escalloniacee, Cephalotacee,
Francoacee, Crassulacece, Hydrangeacee, Ribesacee, Philadelphacece,
Styracacew, Hamamelidacee, Rhamnacee,

Annual and perennial herbs, shrubs, and trees, Flowers abundant; actino-
morphic and zygomorphic; hermaphrodite, pseudo-hermaphrodite, moncecious, and
dicecious. Floral-leaves in
two 4-5-merous whorls, the
lower whorl a calyx, the upper
a corolla. Both whorls spring
from the pitcher-shaped, bowl-
shaped, or. flat hypanthium,
the petals always from the
edge; the sepals, in part, also
from the base of the hypan-
thium. In -the last case the
tube of the calyx is adnate
to the external surface of the
hypanthium. The gyneceum
is in the middle of the hypan-
thium, and consists either of
a single carpel with a uni-. ¢
locularovary (seefigs. 438*1% 4), -
or of several separate unilocu-
lar carpels (see fig. 438* 2, and
p. 74, fig. 208), or of 2-many
united carpels inclosing a
multilocular ovary which may

be adnate to the surrounding Longitudinal sections through the flowers of: 1Cadia varia (Family
Leguminose, division Czsalpinee). 2 Agrimonia Eupatorium (Family

Fig. 488*,.—Crateranthe.

hypanthium at the base only, > Rosacex, division Agrimoniacee). % Chrysobalanus (Family Rosacez,
f h b t th division Chrysobalanacex), 4 Anthyllis Vulneraria (Family Leguminose,
or from the base to € division Papilionacer). (After Baillon.)

middle, or from .the base to
the top (see p. 74, fig. 20845), The ovules are situated on the ventral suture,

and therefore in the inner angles of the loculi. The stamens spring from the
edge of the hypanthium (see fig. 4388*), and are in 1-2 whorls of 3-5 members
each. The fruit is very various (pod, follicle, drupe, nut, berry, &c.), and the
diversity in this respect affords the best means of distinguishing the numerous
families belonging to this alliance. The hypanthium also varies considerably, and

780 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

the families above enumerated may be placed in several groups according to the
form of that structure. In the first group the hypanthium is short as compared
with the floral-leaves, and dries up or detaches itself when the fruit is ripe
(Papilionacew, Cesalpinese, Mimosex, Amygdalex, Rhamnacee); the pistil is simple.
In the second group the hypanthium is flat, and bears the floral-leaves and stamens
on its margin, and several separate unilocular carpels arranged in spirals in the
middle of its surface; it does not fall off when the fruit ripens. In the third group
the hypanthium undergoes further growth when the fruit ripens, and is converted
into an envelope surrounding the nut-fruits, which have developed from the
separate carpels in the interior of the pitcher-shaped cavity of the hypanthium
(Agrimonez, Rosez; see fig. 438*, and fig. 2081” p. 74). In the fourth group the
multilocular pistil is adnate to the hypanthium which surrounds it entirely, and is
converted into a fleshy pericarp (Pomacee; see fig. 20845° p, 74). In the fifth
group only the lower half of the 2-carpellary gynzceum is adnate to the hyp-
anthium, so that its upper half projects above the hypanthium, which is clothed by
the calyx-tube (some of the Saxifragacew). In the sixth and last group the short
hypanthium is only adnate at the base to the multicarpellary, actinomorphic
gyneceum (Crassulacee, Styracacee, &c.). These groups are by no means sharply
defined, and the links connecting them are again described as special families. It
is also worthy of note that honey-secreting tissues in the flowers exhibit extreme
variety of form and position; sometimes they constitute a fleshy lining to the inner,
ae. the upper-surface of the hypanthium (several Dryadesz), sometimes a swelling
round the base of the ovary (several Saxifragaceze), sometimes an annular ridge, or
a group of separate wart-like glands, which are seated on the edge of the extremely
short hypanthium, and are looked upon as metamorphosed stamens (Crassulacez).
Amongst Cesalpinez, Pomaceew, and Hamamelidaces are many species of
arboreal growth, and amongst Mimosex, Amygdalex, Rosez, Spirweex, Rhamnacer,
and Hydrangeacez are large numbers of shrubs and under-shrubs. The majority of
the herbaceous plants of this alliance occur in the families of Papilionaces, Dryader,
Agrimonex, and Saxifragacee. The Cesalpinee include several climbing lianes,
the Papilionacez afford numbers of instances of switch-shrubs, and the Mimosex
exhibit many shrubs with phyllodes. Amongst the Saxifragaces and Crassulaces
many species with thick leaves (see vol. i. p. 827) occur. Cephalotus is insec-
tivorous (see vol. i. p. 131). Compound pinnate or digitate foliage-leaves occur
especially in Rube, Dryadew, Roses, Papilionacez, Cesalpinese, and Mimosez
(see vol. i. p. 583), whilst entire foliage-leaves are found particularly in Amyg-
dale, Styracacess, Crassulacez, Philadelphacew, and Rhamnaces. The flowers of
Papilionaceee and Cesalpinex, and of some of the Saxifragacess and Chrysobalanezx,
are zygomorphie; those of the other families are actinomorphic. In some Mimoses,
Crassulacess, and Styracacew the petals are connate at the base. Small, incon-
spicuous, greenish petals are exhibited by some Agrimonee, Dryadew, Saxifragaces,
Crassulaceze, and by many Hamamelidaces and Rhamnaces; but most of the
species of the alliance Crateranthe have brightly-coloured petals. Dusty pollen has

ANGIOSPERMA, DICOTYLEDONES. 781

only been observed in a very few species (e.g. Poterium). In some Dryadacez and
Chrysobalanew the style springs in a curious manner from the base of the ovary
(see fig. 438**), The fruit is a pod (legume) in Papihionacem, Cesalpinew, and
Mimosew, and these three sub-families are hence often classed together by botanists
under the name of Leguminosw. The fruit of Amygdalew, Chrysobalanee and
Rubew is a 1-stoned drupe, that of Rhamnacezx a 3-stoned drupe. The Agrimoneze
and Dryadew are distinguished by small nut-like fruits, and the Spirwee, Saxi-
fragaceee, and Crassulacew have follicles which dehisce at the upper part of the
ventral suture. In most of the families above enumerated the seeds contain no
endosperm; on the other hand, the thick cotyledons are crammed with reserve
materials, and several of these seeds are used as important articles of human food
(eg. beans, peas, lentils, &.).

The Crateranthe are distributed in all quarters of the globe and in all latitudes.
Cesalpinese and Chrysobalanex belong chiefly to the tropics, whilst Dryadew and
Saxifragacex live principally in the arctic regions and on high mountains. The
Papilionacess are found most abundantly in the area of the Mediterranean flora
and in the steppes in the south-west of Asia. More than 800 species of the genus
Astragalus alone are known to exist in the last-mentioned districts. The Mimosez,
especially the species of the genus Acacia, are represented in Africa and Australia
by many characteristic forms. Roses and Rubew, eg. the genera Rosa and Rubus,
occur in an astonishing variety of species in Central Europe, whilst the Spireex
and Amygdalez are in like abundance in the west of Asia. Crassulaceze are most
abundant at the Cape and in Mexico, but they are also represented by a great
number of species of the genus Sempervivum in the mountainous parts of Southern
Europe. Rhodiola rosea, which belongs to this family, occurs in the arctic flora,
and Sedum repens is found in the Alps at a height of 3000 metres above the sea.
Of the Saxifragacee, Saxifraga oppositifolia reaches the furthest north, it having
been met with at the northernmost spot hitherto visited in Franz Joseph’s Land, at
81° N. Lat. In the Central Alps this Saxifrage is found at an elevation of 3160
metres. Fossil remains of Rosacee, Leguminose, and Rhamnacez have been identi-
fied in the deposits of the Tertiary Period. The number of extant species hitherto
discovered amounts to about 10,000.

Alliance LVIII.—Mprtales.
Families: Myrtacew, Granatacee, Onagracew.

Annual and perennial herbs, shrubs, and trees, with entire foliage-leaves. Vena-
tion consisting of a main axial strand, with sinuous lateral strands branching
pinnately from it. Flowers hermaphrodite, actinomorphic or zygomorphic. The floral-
leaves spring from an annular or tubular hypanthium, which is fused with the
inferior ovary; they are differentiated into calyx and corolla, each of which consists
of a 2-6-merous whorl. The stamens are in 1, 2, or more whorls of 2-6 members

782 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

each, and spring from the fleshy annular or tubular hypanthium which rises up
above the ovary. The fruit is baccate, drupaceous, or capsular.

The Granatacese and Onagracez contain watery juices, whilst the species, belong-
ing to the other families are more or less rich in aromatic substances and etherial
oils. Several are used as spices. Allspice is derived from Pimenta officinalis, and
cloves are prepared from the flower-buds of Eugenia caryophyllata. The Circewes
are small and delicate herbs, the Chamelaucee are dwarf shrubs; whilst the genus
Eucalyptus of the family Myrtacezw includes several species which are amongst the
highest trees in the world (see vol. i. p. 723). The flower in Circea exhibits two
sepals, two petals, and two stamens in order (see fig. 2618, p. 236). In nothera
and Epilobiwm the calyx and the corolla are composed of one 4-partite whorl each,
and the andreecium of 2 such whorls (see fig. 281, p. 282, and fig. 300, p. 354). In
Eucalyptus. Myrtus, and many other genera the number of stamens amounts to over

Fig. 439.—Myrtales,

1 Melaleuca, Longitudinal section through the flower. 2 Flower-bud of Eucalyptus glodulus; the connate sepals are detached
fromithe receptacle as a lid when the bud opens. 8 Fruit of Eucalyptus globulus. (After Baillon.)

100; in Melaleuca, (see fig. 2844, p. 292) the stamens are coherent in bunches. Where
the petals are suppressed, the filiform filaments are white or bright red and yellow.
In the Fuchsias the sepals are coloured like petals; in some species of the genus
Eucalyptus the sepals, which are joined together so as to form a lid, become detached
from the floral receptacle before the flower opens. This remarkable phenomenon
is shown in fig. 489%. The hypanthium which invests the ovary exhibits every
possible transition in form, from a shallow saucer to a long tube (see fig. 266, p. 247).
The ovary is in several families divided by septa, composed of tissue pertaining to
the receptacle, which extend from the central column to the wall of the ovary. In
Granatacex (Punica Granatum) the ovary is in addition divided by a plate of tissue
into an upper and a lower story, and placentas are developed in the chambers of
both stories. The fruits of several Lecythidaces, e.g. those of Lecythis, open with a
lid; those of Eucalyptus axe in the form of hard woody capsules, which dehisce at
the top by means of valves, pores, or slits (see fig. 439°). The fruits of Circwa are
indehiscent; those of Epilobiwm, &c., are capsular, and open by valves. Many
Myrtaces and the Fuchsias have baccate fruits. The fruit of the Pomegranate _
(Punica Granatwm) resembles an apple. The seeds of Bertholletia excelsa of the
family Lecythidacee are known as Brazil nuts, and have a coat as hard as stone;

ANGIOSPERMAE, DICOTYLEDONES, 783

those of the Pomegranate have a fleshy coat, and those of Epilobium are furnished
with hairs. The Myrtales are distributed over all quarters of the globe. The
Chamelauces and Leptospermacess are natives of Australia and the islands of
the Pacific Ocean. Several species of this family help to form Australian bush,
whilst others, especially species of the genus Hucalyptus, constitute entire forests
(see Plate XVI). The Lecythidacess grow chiefly in South America. The Myrtacez
are most abundant. in America, and occur also in Asia and Africa. Europe only
possesses one species, Myrtus communis, which belongs to the Mediterranean Flora.
The Fuchsias are indigenous to Central and South America. The Epilobiums and

Apel x
Fig. 440.—Melastomace, UE branes {
Melastoma Malabathricum. (After Baillon.)

Circzas live principally in the North Temperate Zone, and some species of the genus
Epilobiwm occur in the arctic regions and on mountain heights. Fossil remains of
Myrtaceze and Granatacee have been found in the strata of the Tertiary Period.
The number of species ascertained to exist at the present day is about 2500.

Alliance LIX.—Melastomales.
Family: Melastomacec.

Perennial herbs, shrubs, and trees, with opposite or whorled foliage-leaves.
Leaves entire, with 3-11 curved ribs connected by transverse anastomoses (see
fig. 440). Flowers hermaphrodite or pseudo-hermaphrodite; slightly zygomorphie.
Floral-leaves differentiated into calyx and corolla. The bowl-shaped or tubular

784 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

receptacle is covered externally by the tube of the 4-6-sepalous calyx, is surmounted
by the segments of the calyx-limb, and bears upon it the 4-6 petals which alternate
with those segments. The gynzceum is composed of 3-8 connate carpels. The
3-8-locular ovary is adnate to the hollowed receptacle at the base only, or from the
base to the middle, or from the base to the top. An axis rises up in the middle
of the ovary and bears the placentas, which project into the separate loculi. The
andreeeium is composed of 1-2 whorls of 4-5 stamens each. At the base of each
anther is a spur-like appendage; dehiscence is apical by 1 or 2 small holes (see
fig. 2165, p. 91). The pollen is powdery. The fruit is a berry or a capsule which
dehisces by valves. The seeds contain no endosperm.

The Melastomales belong chiefly to tropical America. Fossil remains have not
been identified with certainty. The number of species ascertained to exist at the
present time is about 2000.

Alliance LX.—Lythrales.

Families: Lythracece, Cupheacew, and Lagerstremiacee.

Annual or perennial herbs, shrubs, and trees with opposite or whorled foliage-
leaves. Lamine entire, with pinnate venation. Flowers hermaphrodite, actino-
morphic or zygomorphic, with calyx and corolla. The cup-shaped or tubular
receptacle is covered externally by the tube of the 3-16-sepalous calyx, the
segments of which project beyond it and alternate with the 3-16 petals which are
borne upon the receptacle. The gynaceum is composed of 2-6 connate carpels. The
2-6-locular ovary is free, and is situated at the bottom of the hollow receptacle.
An axial column rises up in the middle of the ovary and bears the placentas, which
project into the separate loculi. The andrcecium is composed of 1-2 whorls of 3-16
stamens each. The anthers have no appendages, and dehisce by longitudinal slits.
The pollen is adhesive. The fruit is a capsule coated by the cup-shaped receptacle.
The seeds contain no endosperm.

The Lythrales are distributed in all quarters of the globe. They exhibit greatest
variety in tropical America. In the North Temperate Zone they are represented
by the genera Lythrum, Peplis, and Didiplis. No fossil remains are known. The
number of identified species now living is about 400.

Alliance LXI.—Hygrobie.
Families: Hippuridacee, Callitrichaceew, Myriophyllacee, Gunneracee, Trapacee.

Herbs and under-shrubs living in water or in wet places. Flowers hermaphro-
dite, pseudo-hermaphrodite, moncecious, and dicecious; actinomorphic. Floral-
leaves inconspicuous, in 1-2 whorls of 2-4 leaves each. Gyneeceum of one carpel
or 2-4 connate carpels. The under half or the whole of the 1-4-locular ovary is
adnate to the sepals, which cohere so as to form a cup. Each loculus contains one
ovule in its inner angle. The andrcecium is composed of 1-8 stamens. The fruit is

e

ANGIOSPERMAE, DICOTYLEDONES, 785

a schizocarp (Callitriche; see p. 427, figs. 322° and 322 *) or a drupe covered with a
thin coat of pulp; it becomes detached from the receptacle. In the Water Chestnut
(Trapa natans; see vol. i. p. 607, fig. 144) the two whorls of two sepals each which
are adnate to the ovary become a part of the fruit, and their apices project in the
form of four stiff points. The Hygrobie are distributed in every quarter of the
globe, but belong especially to the North Temperate Zone. The Gunneraces
inhabit the Southern Hemisphere. Fossil remains of a plant resembling Myrio-

phyllwm have been found in strata of the Tertiary Period. The number of extant
species known is about 100.

Alliance LXII.—Passiflorales.

Families: Passifloracee, Loasacew, Datiscacec, Samydacee, Turneracece,
Papayacece.

Annual or perennial herbs, shrubs, and trees, with palmately-lobed foliage-leaves.
Venation palmate (radiating). Flowers hermaphrodite or pseudo-hermaphrodite,
and dicecious; actinomorphic. The floral-leaves spring from a cup-shaped hypan-
thium in one or two 4-5-merous whorls. The gynaceum is composed of 3 connate
carpels. The unilocular ovary is free, and is raised upon a more or less elongated
stalk from the bottom of the receptacle, or else it is sessile and adnate to the cup-
shaped receptacle either half-way from the base or from base to top. The ovules
are borne upon three placentas which project in the form of cushions from the
internal wall of the ovary. The andrcecium is composed of 4-5 stamens which
spring from the edge of the cup-shaped hypanthium. The fruit is a berry or a
capsule opening by valves. The seeds contain a fleshy endosperm, in which is
imbedded a straight embryo.

The Datiscaceze have a sepaloid perianth. In the Loasacez and Passifloraceze
the floral-leaves are in two whorls, both of which are petaloid. In the Passifloraceze
a many-membered corona is inserted between the andrcecium and the petals.
The Passiflorales belong chiefly to tropical America. Fossil remains have not been
identified with certainty. The number of extant species known is about 700.

Alliance LXIII.—Pepones.
Families: Cucurbitacee and Begoniacew.

Annual and perennial herbs and under-shrubs (suffrutices). Venation of the
foliage-leaves radiating (palmate). Flowers solitary or in cymes; actinomorphic;
pseudo-hermaphrodite, moncecious and dicecious. The uppermost part of the .
receptacle, which is deeply hollowed, is developed as a hypanthium, and from it
spring the floral-leaves in 1-2 whorls of 2-5 segments each. When two whorls are
present they are either both petaloid in colour or the under whorl is a calyx and the
upper a corolla. The petals are either free or partially coherent. The ovary is

inferior. The ovules are borne on thick pads which are split in two longitudinally,
Vou. IL 100

786 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

and project into the middle of the ovary. The andrecium is composed of 5 or
many stamens which spring from the hypanthium, and are joined at the base to the
corolla. The fruit is baccate or capsular. The seeds contain no endosperm.

The Cucurbitacee have symmetrical foliage-leaves—no stipules, but often
tendrils (see vol. i. p. 696, fig. 165); the Begoniacez have oblique, unsymmetrical
laminz, large lacerated stipules, and no tendrils (see vol. i. p. 420, fig. 110'). The
whorls of floral-leaves are 5-merous in Cucurbitaceee; in Begoniacee the floral-
leaves of the female flowers are arranged in two whorls of 3-5 segments each, and
those of the male flowers in two whorls of 2-5 segments each. Three winged
ridges project from the inferior ovary in Begoniacew. The stalks of the ovules of
Cucurbitacee fill the cavity of the ovary so completely that only small interstices
are left between them. In many Cucurbitacez these stalks are converted when
the seeds ripen into a succulent mass (e.g. in cucumbers, melons, and gourds). In
Begoniacez also they project from the walls into the middle of the ovary, and
the latter looks in consequence as if it were divided into loculi. The andrcecium
exhibits great diversity. In some Cucurbitacese the five stamens are free; in
others they are partially united, and in a third group they are all completely fused
together into a column. In Begoniaces, also, the stamens are connate and form a
column. In many cases the anthers are sinuous, and in the genus (Cyclanthera)
there is a continuous anther all round the column. The Pepones are mainly tropical
plants. The Begoniaceze grow especially in the tropical forests of America, where
they are not infrequently epiphytic. There is still some doubt as to the place of
origin of Melons, Gourds, and Cucumbers. The alliance is represented by the
Squirting Cucumber (Elaterium) in the South of Europe, and by Bryony
{Bryonia) in Central and Northern Europe. No fossil remains have been dis-
covered. The number of extant species hitherto identified is about 1100.

Alliance LXIV.—Cactales.
Families: Opuntiacece and Cactacec.

Perennial plants, whose stems are much swollen or flattened. Flowers solitary;
actinomorphic or zygomorphic; hermaphrodite. The ovary consists of a hollow,
cup-shaped floral receptacle, from the inner wall of which spring filiform stalks
bearing the ovules (see fig. 2091, p. 77). The external surface of the receptacle
is clothed by floral-leaves arranged in a spiral; the lower leaves are small and
inconspicuous, the upper petaloid and brightly coloured (see figs. 441 12345), Inside
the upper tubular prolongation of the receptacle are crowds of stamens arranged
spirally. The pollen is adhesive. The fruit is unilocular and succulent (see fig. 4411 ?).
The seeds contain no endosperm.

The genus Pereskia alone exhibits thick, green foliage-leaves; in the other
genera the leaves are replaced by small caducous scales or thorns, and assimilation
is effected by means of the green cortical tissue of the swollen stems (see vol. i.
pp. 827 and 440). The species of Rhipsalis and Phyllocactus, which are epiphytic

ANGIOSPERM&, DICOTYLEDONES, 787

on the branches of old trees, have much-branched and segmented phylloclades,
which often hang in curves; the segments of the stem in Opuntias are laterally
compressed, and more or less discoid (see vol. i. Plate IV.). The cylindrical stems
of the Queen of Night (Cereus nycticalus, vol. i. Plate VIL, in foreground) are
prismatic, and climb up rocks and the bark of trees by means of clinging roots.
Other species of Cereus, such as Cereus giganteus, which grows to a height of
20 metres, possess erect columnar stems (Plate VII, left hand, middle distance).
Another set of Cereus-species, including the many forms of Mamillaria, Melocactus,
Echinocactus, and Echinopsis, are spherical or truncate; they are covered either
with papille, each of which is crowned by a bunch of prickles (see fig. 441°), or

4 She

s
; (a ©) Ny v6

,

pion

Fig. 441.—Cactacex.

1 Flower. 2 Fruit of Cereus giganteus. ° Mamillaria pectinata. 4 Cereus dasy hus, 5 Echt tus hori: lis. All the
figures reduced.

with tubercles, which coalesce into crests and ribs (see figs. 441* and 4415). The
Cactuses are natives of the New World, and inhabit regions where a short, rainy
season is followed by a prolonged period of drought. The largest number of species
is found in Mexico. Some species also occur at high elevations in the Andes.
No fossil remains are known. The number of species ascertained to exist at the
present time is about 1300

Alliance LX V.—Ficoidales.
Families: Portulacee, Molluginacee, Ficoidacee, Mesembryanthemacece.

Annual and perennial herbs and under-shrubs, with entire fleshy foliage-leaves.
Flowers solitary or in fascicles and glomerules; actinomorphic, hermaphrodite.
The floral-leaves free or else connate at the base; in one, two, or several 2-5-
merous whorls. Either all the floral-leaves, or only those of the lowest whorl,
are sepaloid; in the latter case, the upper whorl or whorls are petaloid. The

788 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM.

gynzceum is composed of 3, 5, 8 or more connate carpels. The ovary is adnate
to the bowl-shaped receptacle at the base only or as regards the lower half of its
surface, or from the base to the top; it is crowned by a radiating stigma of 3-10
rays, and is uni- or multi-locular. A column rises up in the middle of the ovary,
and bears the ovules. In the case of multilocular ovaries, the ovules are borne on
ridges and strands which project from this column into the loculi. The andrceecium
is composed of one or several whorls of 3-10 stamens each. The anthers have no
spurs, and they dehisce by longitudinal slits. The pollen is adhesive. The fruit
is a capsule or an achene. The seeds contain a mealy albumen and a curved
embryo.

The Ficoidales chiefly inhabit dry localities. Only a few species (e.g. Montia
fontana) live in water and on marshy soil. They are distributed all over the globe.
Most of the Portulaceze belong to South America and the Cape. The Mesembryan-
themacez are developed in extraordinary variety in South Africa. There are over
300 species of the genus Mesembryanthemum alone at the Cape. No fossil remains
are known. The number of extant species hitherto identified is about 500.

Alliance LX VI.—Umbellales.
Families: Cornacew, Araliacee, and Umbellifere.

Annual or perennial herbs, shrubs, and trees which flower profusely. Flowers
in capitula, umbels, and cymes. Floral-leaves differentiated into calyx and corolla.
The calyx 4-5 sepalous, with its tube clothing the inferior ovary and the limb re-
presented by 4-5 small teeth, which surround the top of the ovary. The corolla is
likewise 4-5 petalous, the petals free and alternating with the sepals. The gyne-
ceum is composed of a whorl of connate carpels; ovary inferior, 2-5 locular. Every
loculus corresponds to a carpel, and contains a single ovule, which is suspended near
the upper end of the loculus (see fig. 4424), On the top of the ovary is a glandular
disc, which secretes honey (see figs. 442?:+7), The andrcoecium consists of a whorl
of 4-5 stamens. The stamens are quite separate, and stand in a circle round the
honey- secreting disc. The fruit in Umbellifere is a schizocarp (see p. 427;
fig. 8322567 and fig. 442%), in Cornaces and Araliacew a berry or drupe. The
seed contains an abundant endosperm, in which the embryo is imbedded.

The Cornacex are for the most part woody plants, with entire, opposite foliage-
leaves, possessing a venation of arched strands (see p. 231, fig. 260 and vol. i. p. 630).
The Araliacesw, of which the Ivy (Hedera Helix, see vol. i. p. 703, fig. 167) may be
taken as a type, are woody plants with climbing roots, or shrubs and herbs with
radiately-veined foliage, and the Umbelliferse, which are very rich in aromatic
substances, oils, and resins, are for the most part herbs whose stems in many species
reach a length of 3-4 metres, as, for instance, in Ferula communis and Huryangiwm
Sumbul. The foliage-leaves of Umbelliferee are usually much divided (see fig. 442%),
those of Hydrocotyle vulgaris, a plant which lives in swamps, are peltate (see

ANGIOSPERMA, DICOTYLEDONES. 789

fig. 442°). The calyx, corolla, and andrcecium are 4-merous in Cornacez, 5-merous
in Umbelliferee and Araliacew (see figs. 442? and 442° and p. 289, fig. 283 4).
The Umbellales belong chiefly to the North Temperate Zone, but the Araliacese are

Fig. 442, —Umbellales.

1 Heracleum Sphondylium (Family Umbellifere), flowering plant. 2Single flower. 8% Fruit. 4 Longitudinal section through
the fiower of Eryngium maritimum (Family Umbellifere). § Hydrocotyle vulgaris (Family Umbellifere), entire plant.
§ Cornus mas (Family Cornacez), inflorescence. 7 Longitudinal section througha flower. ® Fruit, lreduced; 2,8, 4, 5, 6,7,
and § magnified. (After Baillon.)

also represented by a number of species in the Tropics. Several of the Umbelliferze
are natives of the arctic area of vegetation and of alpine regions. Gaya simplex
occurs in the Central Alps as high as 2600 metres above the sea-level. Fossil
remains, belonging chiefly to the families of Araliaceze and Cornacez, have been

790 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

found in the deposits of the Mesozoic and Tertiary Periods. The number of extant
species identified hitherto amounts to about 1800.

4.—THE DISTRIBUTION OF SPECIES.

Distribution of Species by Offshoots.—Distribution of Species by Fruits and Seeds.—Limits of
Distribution.—Plant-Communities and Floras.

THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

When the dreaded Dry-rot spreads unhindered over the surfaces of wooden
beams, in a dark, damp cellar, its mycelium presents quite a strange appearance.
Grouped in a circle around a dark centre of dead, disintegrating, and crumbling
wood are a number of white spots, joined by indistinct lines to a centre. But this
was not always the case. That which now forms the dead and crumbling centre
was formerly the seat of the first development of the mycelium, then composed of
a coherent network of mycelial threads and appearing to the naked eye as a single
rounded white spot. The mycelial threads then crept out like rays all round the
periphery, and as the white spot increased in diameter its centre became proportion-
ately dark. The mycelial threads forsook their first settlement; they died off, and
the wood they had destroyed then appeared merely as the dark centre of a white
ring. In consequence of its continual widening the ring at length becomes segre-
gated into stars, and is gradually transformed into a wreath of isolated mycelia, or,
in other words, a group of separate but distinct mycelial spots arranged in a circle
arises from a single mycelium in consequence of its radiating method of growth.

The mycelium of Gasteromycetes, of many Fungi allied to Morels, and especially
of many Agarics growing in the forest mould or in meadow humus, also exhibit
under favourable conditions this ring and wreath formation. Although it is not
possible to see the subterranean growth directly, its results are readily recognizable,
since the receptacles rise above the ground from the separate portions of mycelium
and indicate their distribution; these receptacles occur in regular circles, and when
their colour contrasts with the surroundings they are especially conspicuous.
Rings of this kind are shown in fig. 443 formed by the Ascomycete Spathularia
flavida. The subterranean mycelium of this Fungus exercises no injurious influence
on plants in the immediate neighbourhood—at any rate, the mosses, grasses, and
weeds which compose the carpet of the meadow round about show no sign of weak-
ness, but are equally fresh and luxuriant within and without the rings. But it is not
so in meadows where Agarics of the genus Marasmius and others have settled. The
meadow-plants whose roots and root-stocks have been penetrated by their mycelia
die off, and the places can be easily recognized by the withering and discoloration
of their green aérial parts. On first looking at these spots one might easily suppose
that the foundations of old circular walls were lying close under the turf which had

RING-LIKE ARRANGEMENT.

791

Fig. 443.—Fairy Rings in a meadow near Trins in the Tyrol, formed by the ascomycetous fungus Spathularia flavida,
ig. 443.

792 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

in consequence dried up above the stones; that this is not so may be readily proved
by digging, and this shows us at the same time that the humus and roots in these
places are quite riddled and wrapped round by the mycelium of the Fungi named.
The brown and grey ring- and crescent-shaped stripes show up most clearly on
meadows because a parallel stripe of a specially vivid green is usually seen close to
them. The reason of this is that, after two years, new plants develop in all those
places which were formerly occupied by the mycelium, and have been abandoned
by it in its centrifugal growth. Strangely enough, these plants are not the same
species which were killed there in the previous year, but are herbs and grasses
which find a suitable nourishing soil in the places which have lain waste for 1-2
years. The roots and root-stocks of the plants killed by the mycelium have mean-
while decomposed, together with the remains of the mycelium and the receptacles of
the Fungi. The soil is thus manured, and plants which usually settle on fallow
ground grow there in abundance. They raise luxuriant stems and leaves, and thus
is produced on the inner side of each bare stripe a parallel one of a bright green
colour.

This phenomenon has long been noticed by country people, particularly in
regions where pastures are an important feature. It is associated with the
influence of ghosts, witches, and elves; hence the name of fairy rings. In Upper
Austria these bare dry spots are regarded as the rendezvous of the witches, and
Walpurgis Night (1st May) is supposed to be the time when they are produced. In
the Tyrol and other primitive countries the most varied superstitions are held to
account for these curious stripes and patches.

Fairy rings are sometimes formed by plants with underground rhizomes and
runners, although not so frequently as by the subterranean mycelia of the Fungi
named. Some Composites (for example Petasites niveus and P. officinalis,
Arnica Chamissonis, Achillea Millefoliwm), Labiates (Betonica grandiflora, Mentha
alpigena), Irises (Iris arenaria and I. Pallasii), Grasses, Sedges, and Rushes
(Hierochloa borealis, Sesleria cerulea, Carex Schreberi, Juncus trifidus), under
suitable conditions of soil form ring-shaped and garland-like colonies independently
of Fungi. The mode of growth in these plants is like that of the Dry-rot. Young
plants grow up with closely crowded shoots; these then spread out on all sides, and
the connecting links die off simultaneously. In this way the original settlement is
left a bare patch with dried remains surrounded by a circle of distinct and vigorous
offshoots. Though shoots are very numerous they still stand close together even
after they have severed connection, and if their annual growth is but slight it is
some time before an actual ring is formed. It is in this case, however, the more
striking, so that even a casual passer-by cannot fail to notice it. This happens
principally in the above-named Grass-like plants, and among them especially in
Sesleria caerulea, which has attained a certain celebrity in Sweden as the ring-
forming plant. It is there popularly termed elf dansar, and legend has it that the

elves are especially fond of holding their nightly dances on places where rings of
this Grass have been formed.

RING-LIKE ARRANGEMENT, 793

Of course good rings are only produced by the plants named if the foremost buds
produced by the subterranean internodes, i.e. those which form the terminations of
the radiating stock or rhizome, undergo further development, while the intervening
ones perish. This may not be the case under certain conditions, particularly if the
growth of the terminal buds is retarded or stopped. For this reason fairy rings are
formed much less frequently on stony, uneven ground than on flat homogeneous soils;
and the best lands for this kind of fairy rings are pastures stretching over a moun-
tain plateau, or the even floor of a valley.

If specimens of the plants here described are planted on smooth ground, in good
soil in a garden, in places where there is no obstacle to their spreading, they will
form the rings and wreaths in question within a few years. But in spite of this,
very few people are ever able to witness this interesting spectacle in gardens, because
gardeners will not leave the rings alone, regarding the bare patch in the centre as
unsightly and that the existence of a ring is a slur upon their craftsmanship. I
remember noticing this many years ago in the Botanic Gardens at Innsbruck. The
perennial plants were cultivated in certain beds close together, and to each species
was allotted a limited amount of space. When the spring came round the gardener
dug up the periphery of the circle, and planted it in the centre, to catch the escaping
plants, as he put it. In the spots where Mentha alpigena had stood the previous
year only a few withered stumps were to be seen, and not a single living shoot could
be found. But shoots with their tops above the ground could be seen in a circle in
the neighbouring beds, and also in the paths between the beds all round the space
set apart for this species of Mint. These shoots were ruthlessly dug up and planted
again in the forsaken spot. Every year or every second year this capturing of the
fugitives was repeated, not only in the case of the Mint, but in many other instances,
as, for example, Achillea asplenifolia and A. tomentosa, Betonica grandiflora, and
Lysimachia thyrsiflora.

Amongst aérial-sprouting plants. which form rings and wreaths may be numbered
the majority of Moulds, Lichens, and Mosses. The Mould, Penicillium glaucum,
which settles on the fruit rind of oranges, apples, and pears, at first makes its
appearance as a mere point, but later as a circular spot, and finally as a distinct ring
surrounding a brown and rotten centre.

The most striking of the ring-forming Lichens are those which stand out from their
substratum on account of their colour. Most noticeable in this respect are the white
Parmelia conspersa, which contrasts with the dark slate rock, and the saffron-yellow
species Amphiloma callopisma and Gasparrinia elegans. The gelatinous Lichens,
dark olive-green normally, but black when dried, especially Collema multifidum
and C. pulposwm, often form such regular wreaths on a light background of lime-
stone that they look as if they had been drawn with compasses, and the tiny
yellowish-red Physcia cirrochroa has a particularly elegant appearance when it
has radiated out from the hundreds of spots where it established itself on the flat
surfaces of a steep calcareous rock. One might almost think that the small orange
wreaths had been painted in with a brush. They also remind one of the fleecy

794 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

clouds in the evening sky, whose edges are reddened with the rays of the setting
sun; and if I am not mistaken, this Lichen has obtained its name on account of this
resemblance.

The chief Liverworts and Mosses which form rings and wreaths when they grow
on the flat surfaces of steep rock-faces and on the bark of old tree-trunks, are
Frullania dilatata, Radula complanata, Amblystegium serpens, Anomodon viti-
culosus, and Hypnum Halleri. When they first settle they are scarcely noticeable
on account of their minuteness, but they spread very rapidly, their firmly adherent
stems forking and radiating out in all directions, the whole plant at a little distance
now forming a greenish-yellow spot of circular outline. While growth proceeds in
this way round the periphery of the Moss-plant, covering the rock or bark like a
carpet by the multiplication of its outer forked branches, the older parts near the
original place of settlement become dry, disintegrate, and are blown away like dust
by the wind, the naked rock or bare bark thus again coming into view. In this
way 5, 10, or 20 new Moss-plants are derived from the original one, and stand in a
circle round the bare centre. This circle widens from year to year, until at last it is
interrupted by gaps, and then 20 or more specimens of the Moss are seen adhering
to the substratum arranged in a circle more than a span from the original settling
place.

In order that the ring or wreath arrangement of the offshoots above described
should obtain, it is necessary that the original plant should dry up and decompose,
and that the shoots which radiate from it should also die off behind in proportion
as their growing points travel away from the centre of the settlement, and, finally,
that no new ring-forming species should establish itself, or spread on the dead centre
for a considerable time. These conditions are only comparatively rarely fulfilled,
and this is the reason that ring and wreath formations are relatively so scarce.

It happens much more frequently that the plant forming the starting-point of a
colony, after it has sent out creeping threads of cells, runners, shoots, and the like
in all directions, does not itself perish, but remains living and active in the centre of
its separated shoots, even sending out new shoots year after year. In the same
way the separated shoots repeat the parent-method of growth, 2.e. they send out
shoots in all directions like the mother-plant, though perhaps less regularly, and
thus of necessity some of the young shoots come back to the bare centre and settle
down where the mother-plant originally stood. The following phenomenon may
also be observed: A plant gives off annually a pair of horizontal shoots on one side
only, let us say on the south; their buds in the course of time become independent
plants, and each again sends out a few horizontal shoots towards the south. Ina
few years’ time these offshoots give rise to 20-80 plants, which are more or less
distant from the starting-point, according to the length of the shoots. In all these
cases the offshoots are not arranged in a ring or wreath round an empty centre, but
in lines or clusters.

Like the ring- and wreath-forming colonies, the offshoots, forming lines and
clusters, may be underground or aérial. The receptacles of many Fungi emerge in a

LINEAR AND CLUSTERED ARRANGEMENT. 795

clearly lineal arrangement from the mycelial threads running below the surface of
the ground and in dead, rotten tree-trunks. Some Mosses form colonies in very
regular lines from their rhizoids and horizontal underground protonemas. The most
conspicuous, however, is the line formation produced by roots which run horizontally
below the soil, The Aspen (Populus tremula), the Sea Buckthorn (Hippophae
rhamnoides), Lycium barbarum, the Raspberry (Rubus Ideus), the Dwarf Elder
(Sambucus Ebulus), Asclepias Cornuti, various species of Linaria and Euphorbia,
and numerous other plants (¢f. p. 27) produce special horizontal underground roots,
which give off buds towards the upper side. The shoots arising from these buds
form separate independent plants after the root which formed them has died away.
Obviously the plants follow the direction of the roots, and are arranged in rows.
Even for years afterwards the line-like arrangement of the individuals in such
colonies can still be recognized. When the bud-forming roots are of considerable
length, the terminal offshoots are sometimes situated at some distance from the
mother-plant. I saw single offshoots from the root of an Aspen push up through
the ground 30 paces from the woody parent stem. Stems of Asclepias Cornuti
spring up from the thick horizontal roots deep under the ground, at intervals of
about 40 cm., and in them also can the linear arrangement be sometimes very
clearly seen. When the individual offshoots in their turn give rise to horizontal
roots, the line-formation is lost sight of more and more, and a scattered group
spread over a wide area is the result. Sometimes the older portions of the colony
die off completely, and as the individuals in one direction disappear, those in the
other grow more luxuriantly. One might almost suppose the whole group to have
taken a few steps forwards. This phenomenon can be seen particularly well in
Raspberry bushes. On suitable soil a group of Raspberries will move about 2 paces
every year, and therefore, after 10 years, they may have moved about 20 paces. If
Raspberry bushes are planted near an inclosed piece of ground along a fence or
hedge, it may happen that ten years later not a single one can be seen in the original
_ place, while on the other side of the fence, in the neighbouring piece of ground, quite
an assemblage of Raspberry plants has come into existence.

The clustered or linear colonies which spring from underground tubers have the
following very simple history. After a tuber has been fully formed on the under-
ground shoot of a plant the slender bridge-like connections which have hitherto
served for the conduction of food break down by the decay and decomposition of
their tissues. The new tubers thus separated from the mother-plant send out stems
from their buds, after the necessary period of rest these push up above the ground
and also give rise to new subterranean shoots with tuberous swellings. These
fresh tubers, after they have become disconnected, again form the starting-points for
tuber-forming plants. This goes on until after a few years the soil all round the
place where the first tuber had been is crowded with hundreds of separate tubers,
and corresponding to these above the ground is a group of hundreds of separate
leafy stalks. It depends of course on the number and length of the underground
tuber-forming shoots whether the group is crowded or scattered. In the Artichoke

796 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

(Helianthus tuberosus) the tuber-forming shoots are short; the colony is therefore
crowded, and only spreads slowly over a larger area. The Alpine Enchanter’s
Nightshade (Circwa alpina; see fig. 444%) forms elongated tubers at the end of
shoots 6 cm. in length, about 5 of them round the mother-plant, whilst each of the
new plants arising from these tubers repeats this formation in the same colony.
Since 6 cm. is a considerable length compared with the size of the Enchanter’s
Nightshade, the group is scattered and in a few years extends over a considerable
area. The tuber formation of Thladiantha dubia, a gourd-like plant growing in

Fig. 444.—Plants with tubers and bulbs whose mode of growth leads to the formation of colonies arranged in lines and
clusters. 1 Muscari racemosum. 2 Thladiantha dubia. 8 Cireea alpina.

Eastern Asia, is especially luxuriant; its shoot-formation ig shown in fig. 4447, In
this plant a whole series of tubers which are chained together by thin threads
4-8 cm. long is formed on each shoot. Usually they form series of 5-10, and such
a chain is about 50 cm. long. As a new plant grows from each tuber and again
produces chains of underground tubers, the Thladiantha in a few years may occupy
an area of 10 sq. metres, and will form a cluster which is both crowded and rapidly
increasing in circumference. A further excellent example of the same thing is
Glaua maritima which often spreads in the most diagrammatic manner in bare
sandy places near the sea-shore.

Many tuber-forming plants producing clustered colonies inhabit marshes, espe-
cially such as are liable to great alteration in the level of the water and are
exposed in years of drought to the danger of temporarily drying up. Many Pond-

LINEAR AND CLUSTERED ARRANGEMENT.

797

weeds (Potamogeton), e.g. Potamogeton pectinatus, form a large number of small
tubercles on their shoots which creep horizontally through the mud; Scirpus
tuberosus, like the Alpine Enchanter’s Nightshade, forms underground shoots 10-15
em. in length, each terminating in a tuber as large as a chestnut, and since the
plants to which these tubers give rise themselves repeat this formation of off-
shoots, the diameter of the clustered colony increases about 20-30 cm. every year.
The Arrow-head (Sagittaria sagittifolia) also develops peculiar tubers. In the
autumn, offshoots whose scale-leaves terminate in a sharp point not unlike those of
the Couch-grass spring from the knotty stems hidden in the mud. The leaf which
envelops the swollen end of the offshoot has a stiff point and plays the part of an
earth-borer or rather of a mud-borer, since it makes a path for the offshoot which
may elongate as much as 25 cm. The swollen end of the offshoot, which is about
the size of a hazel-nut, bears a small bud with greenish, closely-folded leaves, and
this, together with its tuberous support, remains alive during the winter, while the
plant to which the offshoots owed their origin perishes. In the following spring
cach of the small buds grows up into a new plant at the expense of the reserve-
materials stored in the tuber, and now instead of the old dead plant we have a small

group of young independent plants rising from the mud.

The colonies of offshoots arranged in lines and clusters, which are developed from
underground rhizomes and shoots, elongate horizontally, and form buds laterally
and at their growing point, and in the same proportion as they fork and divide in
front they die off behind, so that the individual sprouts become separated. To this
category belong several species of Dentaria, Anemone, Couch-grass (Agropyrum),
Mint (Mentha), Yarrow (Achillea), Willow-herb (Epilobium), Butterbur (Petasites),

and the Woodruff (Asperula odorata).

The length of the underground shoots.

which form the buds in these plants is very varied, as will be clearly seen from the

table we insert here.
Centimetres.

Anemone ranunculoides .
Monarda fistulosa. . . 5-10
Melissa officinalis . . ea
Origanum vulgare. .
Achillea Millefolium. .
Equisetum arvense .
Asperula taurina .
Oxalis corniculata.
Betonica grandiflora . .
Tanacetum Balsamita
Aster salignus . ar

‘ 15-20

10-15

Dentaria glandulosa
Carex arenaria. .
Juncus arcticus

Centimetres.
Epimedium alpinum. .
Silene alpestris . : }ro-20
Mentha viridis .

Asperula odorata .

Mentha piperita . .

Rubia tinctorum . . jo
Senecio Fuchsit

Mercurialis perennis. .

Mentha crispa . . | 26-30
Agropyrum repens ‘
Aigopodium Podagraria

Convolvulus arvensis. . \s0-3 ,
Saponaria officinalis . . J
Potentilla bifurca. . 35-45

Centimetres.

: lon.
3 fase

Hierochloa borealis
Urtica dioica
Carex pilosa

Glaus maritima .
Arnica Chamissonis

Daphne Philippi .

Senecio fluviatilis . 55-60
Tussilago Farfara :

Solidago canadensis . . }eo-rs
Petasites niveus a.

Mentha alpigena : } 15-85
Nardosmia fragrans .

Epilobium angustifolium } 5-200
Petasites officinalis 100-150

These numbers do not represent the lengths of single internodes, but those otf
the whole annual underground shoots which may consist of many internodes.
For example, the year’s underground shoot of the Umbellifer Zyopodiwm Poda-
graria has 8 internodes, of which the proximal one is the longest and the distal the

shortest.

798 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

The rapidity of the extension and the dimension of the colonies which are pro-
duced from rhizomes and runners depends upon the length of the annual shoot, and
upon whether or not the soil is favourable to the spreading of the offshoots, just as
it does in the linear or clustered colonies arising from underground roots and tubers.
In wood-clearings and on the banks of rivers many of these plants develop in a
surprisingly short time, as, for example, Calamagrostis Epigetos, Epilobium anguste-
folium, the North American Golden Rod and Rudbeckias (Solidago Canadensis
and Rudbeckia laciniata), and these also have the property of suppressing and
destroying all other vegetation in places where they have taken possession. This
fact is turned to practical account by farmers who use certain Grasses which form
linear and clustered offshoots to bind together loose soil, especially river sand. But
there are also plants in this category which are veritable plagues to the farmer, the
establishment and propagation of which he opposes by every means in his power.
Examples of these dreaded plants, which, when they establish themselves in the
fields and garden-beds, hinder the development of other plants, are furnished by the
Gout-weed (Agopodiwm Podagraria), the Stinging Nettle (Urtica dioica), and
the Fuller’s Thistle (Cirsiwm arvense). Wherever these have settled on cultivated
ground and penetrated the soil with their offshoots there is nothing for it but to dig
up the whole ground and to carefully remove all the shoots. Unfortunately even
this laborious task is not always rewarded with the desired result, for in spite of the
utmost care it may happen that small fragments remain, and these form the nucleus
of a new colony of weeds. In a short time a new group appears above the soil
which has been cleared with so much care, and. a fresh digging and still more careful
clearing of the ground is necessary. These clustered colonies have a characteristic
appearance when foliage-leaves spring from their underground stem-structures, the
large blades being borne on almost equally long erect stalks, as is the case, for
example, in the Butterbur (Petasites officinalis) and numerous tropical Aroids.
Wide tracts are then to be seen covered exclusively with their large luxuriant foliage-
leaves, all other vegetation being suppressed. The formation of offshoots and the
production of clustered colonies also occurs to a remarkable extent in the common
Reed (Phragmites communis). Once settled on suitable soil it will cover the
widest areas in uninterrupted and unhindered march, suppressing and destroying
all other plants. On the lower Danube there are many lowlands so thickly set with
Reeds that in several hours’ journey only a few small inconspicuous plants will
be seen beside the Reed haulms. This Reed is also interesting from the fact that its
offshoots can arise just as well under water as under the ground, and it may serve,
in some respects, as the type of a group of plants which, by reason of their
amphibious nature, play an important part in the transformation of submerged into
dry land.

On the other hand, the variety of the protonemal threads, runners, shoots, and
creeping stems which spread above-ground from the offshoots of these colonies is
almost inexhaustible. And this is readily intelligible. The processes which are
connected with their formation are much more varied in plant-members which grow

CLUSTERED ARRANGEMENT. 799

in the light and in open air than in those which develop under the water or the
soil, or, perhaps we should rather say, that above the ground the greater fluctuations
in light, moisture, and temperature bring about corresponding modifications in the
vital processes. Moreover, the substratum presents every imaginable gradation
from shifting quicksand to heavy clay, from steep rock-faces in one place to the
bark of old tree-trunks in another, all these having by no means the same effect on
the formation of offshoots. One of the most noteworthy processes occurring above
the ground leading to the formation of clustered offshoots is that exhibited by
Moss-protonemas. By protonema is meant a web of threads which spreads some-
times as a loose, open network, sometimes as a thick felt, over rock, clay, sand, earth,
humus, bark, and decayed wood, the individual cells becoming the starting-points

of new Moss stems. This protonema may be compared to a web of Strawberry
runners which has spread over the ground in a wood-clearing. Just as small plants
spring up from the thread-like runners in this case, so Moss-plants are produced
from the protonemal threads, and by the dying away of the latter become isolated.
In many Mosses the end comes with the formation of this clustered arrangement,
as, for example, in the tiny Mosses classed together as Pottiaces, of which one
species, Pottia intermedia, is shown in fig. 445. This plant has the following
remarkable history. During the period when most other plants are engaged in
active nutrition and reproduction it remains with its rhizoids and part of the
protonemal threads imbedded in the ground. Numerous scattered spores also
remain resting in the ground until at length the time for aérial development
arrives. Strangely enough, however, this is not until late in the autumn, when the
leafy trees have discarded their foliage and autumnal mists drift through their bare
branches. Then on the surface of the bare, cold, damp earth appear green threads
which at first look like algal filaments, and on these small buds are formed (see
fig. 445). In the course of a few weeks Moss-plants grow up from these buds

800 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

which become independent by the gradual withering and decomposition of the
connecting pieces of thread. They form spherical spore-capsules, and with the
scattering of the spores they wither and die. These plants are only a few milli-
metres high, but they are clustered together in such thousands that they form a
velvety carpet over the soil, their emerald-green colour being the more striking as
the last remains of the neighbouring vegetation have assumed the dull hues of decay.
The Luminous Moss (Schistostega osmundacea) growing in the holes and clefts of
slate mountains (already described in vol. i.), the protonema of which is depicted in
Plate I., also forms loose colonies of separate Moss-plants from the green threads
which creep over the clayey soil in the hollows. These plants die off after they
have ripened their fruits. Of course the development is in this case not so rapid
and does not occur in the late autumn as in Pottia intermedia.

A peculiar formation of offshoots may be noticed in epiphytes which climb over
the bark of old trees and possess only short ribbon-like roots adhering to the damp
bark, but none which grow down into the ground. Their stems and leaves invest
the substratum like a carpet, as, for example, in several tropical Aroids of the genus
Pothos, and in Maregravia. The growing stem forks, and later on by the dying
away of older portions behind the fork the two branches are separated and isolated.
Each in its further growth may go a different way, one climbing up this and the
other up that branch of the tree-trunk which serves as support; and, since this
process is repeated, several independent plants of Marcgravia and Pothos may be
found on the crown of the tree, all of which are to be regarded as natural offshoots.
The same thing occurs in numerous Ferns, which grow on the bark of trees and in
the humus-filled clefts of rocks, and in all those plants whose creeping aérial stems
grow and branch at one end while they die off to a corresponding extent behind, as
in many creeping species of clover, for example. As the annual increase in the stem
of these plants is but small, the separated individuals move very slowly from one
another, and several years elapse before the offshoots have formed a group which
extends over an area of a square half-metre.

The result is obtained comparativély much quicker when the offshoots are formed
by runners and shoots. In one section of these plants, of which the Saxifraga
flagellaris (fig. 446), a plant widely spread through the Arctic region and in the
high’ mountain districts of the Himalayas, Altai, and Caucasus, may be taken as a
type, only a single bud is developed at the end of a slender thread-like shoot. This
takes root where it touches the ground, and grows up into a rosette. Not until the
nourishment of the rosette by the rootlets which have been sent into the ground is
assured does the long thread, terminated by the bud, die off, the connection with
the mother-plant being thus severed, whilst the rosette now forms an independent
plant. Since the shoots are usually numerous and radiate outwards the mother-
plant in course of time becomes surrounded with an actual garland of rosette-shaped
offshoots, and in a few years a fairly large area is covered with hundreds of larger
and smaller rosettes, which, however, no longer show the circular arrangement, because
the shoots of neighbouring rosettes often cross, and consequently the circles intersect.

OFFSHOOTS ON RUNNERS. 801

Everyone knows the long runners of the Strawberry plant (Fragaria vesca).
Here buds arise at the intermediate nodes as well as at the tip of the runner, and these
develop into new plants after the thread-like connecting portions have perished.
Suppose a Strawberry stock sends out three runners during the summer; each takes
root at 5 nodes, and from each node a bud, i.e. an offshoot, develops, so that the
following year the mother-stock is surrounded by fifteen daughter-plants. It should
be noted that the length of the internodes in each runner is unequal. For example,

Fig. 446.—Formation of a clustered colony by means of aerial runners in Saxifraga flagellaris.

in one which had extended over the ground in the shade of the wood, the first inter-
node was 387, the second 34, the third 31, the fourth 30, and the fifth and last
22 cm.; thus the offshoots were the closer together the greater their distance from
the mother-plant. Next summer fifteen new offshoots were again formed from
each of the original fifteen, arranged in exactly the same way, and in the forest-
glade, where two years previously there had been only a single Strawberry plant
occupying a space of 50 sq. cm., there would now be 200 plants distributed over a
space of about 3600 sq. cm.

The lesser Spearwort (Ranunculus reptans), the Ground Ivy (Glechoma,

hederacea), and the creeping Cinguefoil (Potentilla reptans) display quite as
VoL, IT. 101

802 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

considerable an increase and distribution as Strawberries. The accompanying
table gives the length of runners and shoots of some well-known species in which
the formation and rapid distribution of offshoots is particularly noticeable on
suitable substrata.

Centimetres. Centimetres, Centimetres,
Saxifraga Aizoon . 4 Lycopodium annotinum. . 30-40} Vinca herbacea fg ge ae HO
= cunetfolia . . 6 Saxifraga sarmentosa . . 40 Fragaria Indica on A, Hen 28D
5 Geum . ‘ 8 Ranunculus Flammula . . Potentilla anserina ‘ 110
» flagellaris . . 10 Geum reptans . . - 750 Glechoma hederacea s « 126
Sempervivum stenopetalum . 12 Glyceria fluitans . . Potentilla reptans. . . . 130
Viola odorata oe 13 Ltthospermum purpureo- Rubus saxatilis . ve « 10
Arabis procurrens . 16 ceruleum . Se kn BE Fragaria vesca. . . . 150
Androsace sarmentosa . 18 Ranunculus reptans . . 60 Vinca major i kh ow 200
Ajuga reptans. . . . 20 Tiarella cordifolia é 65 Rubus Radula . . . . 3800
Hieraciwm flagellare. . 30 Vinea Libanotica. . . . 66 » Oijrons . . . 650

In those cases in which plants change their position by the development of
offshoots in any direction, whilst they die off in the opposite one, progress is always
restricted, The offshoots penetrate only by slow degrees in the surrounding soil,
and many years elapse before a space of 100 metres is traversed in this way. The
change of position is much more rapid when the offshoots become detached from
their place of origin and are carried to a new spot by special mechanisms of transit,
by currents of water, the wind, or finally by the help of men or animals. In this
way it may happen that single detached cells, cell-groups, buds, and shoots may be
carried vastly further than 100 metres in a few minutes, through long valleys, over
steep precipices, or even over high mountain ridges. This rapid distribution is not
indeed so certain in its result as the slower mode of progression. It may easily
happen that the wind or water current lands the detached offshoot on some spot
where further development is impossible, where it must inevitably perish. Appa-
rently, however, this disadvantage is compensated for by the immense quantity of
such detached offshoots. Again, there are plants which form two kinds of offshoots,
those which propagate slowly but surely, which are few in number, and others,
developed in large numbers, which are distributed rapidly but less certainly.

Only a very small proportion of plants develop offshoots which after they
become detached reach a new locality spontaneously, by means of special organs of
motility. This class of brood-body is always aquatic and of very small size, and
its development can only be followed under the microscope. The best-known
examples are Fungi, belonging to the Saprolegniacee and Chytridiaces, the
dark green Vaucherias, and other species of Algew. The Saprolegnias are sapro-
phytes growing in and on the bodies of animals which have died in the water—
not only fish, crustaceans, and insect larve, but also birds. They form delicate,
thread-like, tubular hyphe, which ramify repeatedly, and part of which penetrate
into the corpse like a root-plexus, while the rest rise up above the body in the form
of white or grey felt, which floats in the water. Single tubular erect hyphe
assume a knob or club-shaped form, and their protoplasm divides up into numerous
portions. Ultimately the club-shaped tube opens at the apex, and the little proto-

DISPERSAL BY WATER, 803

plasmic bodies (swarmspores) escape (cf. fig. 192, p. 17). What happens next differs
according to the species. In the genus Saprolegnia the individual swarmspores
have two cilia, by means of which they immediately swim away (see figs, 192° and
192"); in Achlya, on the other hand, the swarmspores group themselves into a
round ball in front of the opening of the tube as they escape (ef. fig. 1924234), and
at first possess no cilia. They surround themselves there with a delicate capsule,
which apparently consists of cellulose, but they do not remain long in this condition.
A few hours after, they leave the capsule and assume a bean-shaped form, being
now provided with cilia which enable them to swim about in the water. They only
swim about for a comparatively short time. When they have settled on some spot
they lose their cilia, surround themselves with a cell-wall, and become the starting-
point of a new plant; therefore they must certainly be regarded as offshoots. The
Chytridiacex have a similar offshoot formation. These too are devoid of chlorophyll,
but they are true parasites, not saprophytes like the Saprolegniaceew. They prefer
green water-plants for their hosts, penetrating into their cells, killing and destroying
the protoplasm, and then develop thick tubes which project beyond the host-plant,
and in which the protoplasm becomes divided up into numerous spherical portions.
The tubes open at their apex sometimes by the raising of an actual lid (see fig. 192°),
sometimes by the dissolution of a limited portion of the cell-wall, so that a hole
results from which the isolated protoplasts are expelled. On its escape each of
these offshoots is spherical or egg-shaped in form, and possesses a single long cilium.
This cilium serves as a swimming organ which in many species actually causes
a hopping and springing movement. In order to avoid repetition, we may refer to
the description of the swarmspore-formation given at vol. i. p. 29, in the case of the
Vaucherias and Spheerellas.

On the whole, as we have already stated, the formation of offshoots which swim
about independently in the water and seek out new spots suitable for settlement is
restricted to a very small section of water-plants. Offshoots which, after their
detachment from their place of origin, are carried passively by water currents with-
out exercising any directive influence, and are stranded at some distant spot, are of
much more frequent occurrence, Of these water-plants we might mention in the
first place the filamentous green Alge which cover with slimy masses the surface
of slowly moving water or stones at the bottom of rapid streams. In many of
these plants several times during the year do the dividing membranes between the
individual cells break down into mucilage so that the cells become free and are
carried away by the flowing water. Each of these cells may again give rise to a
new thread by repeated division. We cannot easily conceive a more simple method
of propagation and distribution than this. The offshoot-formation in the Floridex
is hardly less simple. Whether the whole plant is composed of rows or of open
networks of cells, four protoplasmic balls, the so-called tetraspores, are formed in
various situations on the plant; these are liberated into the surrounding water and
carried away by the current. They adhere to some firm spot under water and
there grow up into new plants. In most instances the protoplasm of the cell in

804 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

which the offshoot formation occurs is divided into four, more rarely two or eight
clumps are formed by the splitting and dividing of the protoplasm, and most rarely
of all is the whole undivided protoplasm of a cell transformed into a single offshoot.

The small group of water-plants known as the Hydrodictyacee display a peculiar
offshoot-formation. In the elegant Water-net (Hydrodictyon utriculatum, ef.
p. 640), whose cylindrical cells form a closed net with hexagonal meshes, the cells
each originate new plants as Water-nets in miniature. The protoplasm in one of

Fig. 447.—Frogbit (Hydrocharis Morsus-rane), The winter buds in process of detachment from the ends of the submerged
stolons,

the cells which is preparing for offshoot-formation divides into many thousand parts
which quiver in a remarkable way and pass between one another, and are said to
undergo the so-called swarming motion. This lasts about half an hour, then the
swarming portions, whose rod-like form can be recognized in spite of their minute-
ness, come to rest, arrange themselves into nets with hexagonal meshes (see
figs. 3703.45 p, 640), and now each cell contains a tiny Water-net. The outer layer
of the cell-wall in which this grouping has taken place is partially dissolved. The
little net, at first still inclosed in a pellicle of protoplasm, slips out and swims freely
in the water as an offshoot. In 3-4 weeks it has attained the size of the Water-net,
from one of whose cells it emerged, and in each of its own cylindrical cells the same
process may be repeated. A similar process is observed in the small water-plant

DISPERSAL BY WATER, 805

called Pediastrwm, which is closely related to the Water-net, and of which one
species is shown in figs. 370%7.8 p. 640.

The distribution of bud or sprout-like offshoots is seen especially in the Duck-
weeds, Alismacex, Potamogetons, Utriculariaces, Droseracezx, and Primulacez.
Most of the Duckweeds (e.g. Lemna polyrrhiza and L. arrhiza), which float during
the summer on the surface of still water, towards the autumn form organs on their
flattened stems which become detached from the summer plants, sink to the bottom

Fig. 448.—Frogbit (Hydrocharis Morsus-rane). 1 Winter buds rising to the surface in spring. 2 Young floating plants
which have developed from such buds. & Older floating plants.

of the lake, and stay there during the winter. Each of these organs is pocket-
shaped, and in the hollow the next year’s shoot is already laid down—of course, as
a minute structure whose semicircular free end scarcely projects above the closely-
adjoining edges of the pocket. These detached winter buds sink because their cells,
even those of the epidermis, develop large starch grains which are crowded together,
and literally fill up the lumens of the cells. There are no air-spaces like those which
cause the summer-plants to float on the surface of the water; the stomata as yet are
closed, and the whole body, hermetically sealed from the outer world, now has a
specific gravity which causes it to sink down to the bottom of the water, where it
is protected against the frost. There it remains in a resting condition during the
winter. At the beginning of the warmer season the bud wakes from its winter

806 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

sleep, the starch-grains are used up in the building of the young stem, and the
growing buds of these species of Lemna again rise to the surface of the water,
because the cells which had served as storehouses for the starch become empty, and
because air-spaces are formed in the new tissues.

The same change of position during the year is also observed in the offshoots of
the Frogbit (Hydrocharis Morsus-ran), which is common in still waters through
the whole of Europe and a great part of Asia. Although this plant is abundantly
provided with roots, it never fixes itself by them to the slimy bottom of the pool in
which it lives. Throughout the summer it remains floating on the surface, spreading
its foliage like the Water-lilies on the top, while its roots hang below in the upper
layers of water. Its propagation in the summer is very rapid by the formation of
offshoots. These arise in the axils of foliage-leaves from the very short, erect, floating
stem, and are rather long, resembling thick threads, which keep close to the surface
of the water, and grow in a horizontal direction. Each shoot terminates in a bud,
and this quickly opens, sending up green foliage to float on the water, and a bunch
of roots below. In a very short time the plant thus formed resembles the parent
which gave it origin, and is itself able to develop new shoots. Thus it comes about
that in a few weeks the surface of the water is covered with innumerable floating
plants of Frogbit, every 10-20 being connected together by horizontal strands. The
pretty flowers now rise above the surface from the stronger plants. The flowering
is, however, of short duration, and is seldom successful, ¢.e. fruits with fertile seeds
are rarely produced. As soon as the blossoming is over and autumn approaches,
new shoots ending in buds appear. They are shorter than those of the spring, and
they sink lower on account of the greater weight of the buds they carry. The buds,
too, have a rather different form. They are firm, and wrapped in closely-fitting
seale-leaves, and they almost attain the size of a small date-seed. As soon as the
bud is provided with the requisite amount of starch and other reserve food-substances,
it becomes detached from its filamentous support, and sinks down (see fig. 447) till
it rests on the mud at the bottom of the pond. The plants floating above, which
gave rise to them, die off completely and decay. It is high time indeed to quit the
field above, for the surface of the water is soon covered with a sheet of ice, which
renders all vital activity impossible for months. When spring again arrives, and
the ice vanishes from the pools and ponds, new life rises up from the mud below.
The buds of the Frogbit which have passed the winter there become spongy, the
cell-cavities fill with air, and the whole structure rises to the surface (see fig. 4481).
Arrived there the scale-leaves rapidly separate, green leaves expand their blades on
the sunlit surface, roots hang down into the water, and before long, shoots are again
developed as already described (fig. 4482). Obviously deviations of position and
sometimes considerable changes of place are brought about by the sinking and rising
of the buds in the water. It is observed, too, that the Frogbit is very variable in
regard to its position, and that sometimes a place whose surface was one year
covered with numberless plants will in the year following present no trace of them,
while new colonies will have developed at a distance.

DISPERSAL BY WATER. 807

The Bladderworts (Utricularia), Aldrovandias (Aldrovandia vesiculosa, see
vol. i, p. 151), and the Water Violet (Hottonia palustris), which desert the cold
upper strata of water as winter sets in, and sink down to the relatively warm
depths below, develop special wandering buds for this purpose; these are not
enveloped in scale-leaves like those of the Frogbit; they are in reality merely much
abbreviated shoots whose leaves are so crowded and folded so closely together, that
the whole shoot looks like a rounded green ball. These balls at first remain con-
nected to the piece of the floating stem which gave them origin. This attachment
is lost towards the end of autumn, and the little buds sink down to the bottom
of the pond and necessarily get distributed in various directions. Next summer,
when the balls leave their winter quarters and are again carried to the upper strata
of water, they expand into foliage-bearing plants. It has been already stated
(vol. i. pp. 76 and 658) that the Water Soldier (Stratiotes aloides), which is closely-
related to the Frogbit, undergoes similar changes during the year, and we need
here only draw attention to the fact that it sinks down to its winter quarters
at the bottom of the pond as an open rosette, and not in the form of buds, and rises
again the ensuing spring when the weather is more favourable.

The Pondweeds Potamogeton crispus, obtusifolius, pusillus, and trichoides
behave differently from the marsh and water plants hitherto described. Here,
as autumn approaches, buds are developed which become detached from the old
decaying stems (fig. 136, vol i. p. 551), and sink down to the bottom of the pond;
but in the following summer they remain sticking in the mud at the spot where
they fell, and do not rise again to the surface. They send out roots and develop
much-branched leafy stalks, and these rapidly grow up to the surface of the water.
These Pondweeds, firmly rooted to the bottom of the pond, multiply not only
by these free-swimming offshoots, but also by stolons which creep far and wide
through the mud; but of course the plants are distributed to much greater distances
by the sprouts or buds which are developed in the autumn on the upper internodes,
and which then become detached and float in the water, than would be possible by
the creeping stolons alone.

A very remarkable distribution of offshoots is to be observed in the marine
Cymodocea Antarctica, which is very common on the coast of Australia, south of
the Tropics. This plant has an erect stem, thickly covered with dull-green foliage-
leaves, arranged in two rows. The lower leaves fall off prematurely, and the bare
scarred stem then carries only a bunch of ribbon-shaped leaves at its summit.
Towards the close of the winter the end of the stem above these leaves is seen to
become peculiarly modified. Its internodes become much contracted, and at the
lowest node is developed a scale-leaf with four lobes, which surrounds the leaves
developed from the upper nodes, like a cup. Buds arise in the axils of one or two
of these leaves, while the leaves themselves die and decay. The parenchyma of the
four-lobed, cup-shaped scale-leaf also decays, and only its stiff veins remain, so that
instead of the cup, there are now only comb-like scales. After this alteration
has taken place, the tissue of the stem below the pectinate scales breaks across,

808 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

and the whole shoot-apex, separated from the lower part of the stem, which has
long been in a leafless condition, is carried away by the currents of the water.
How far and for how long the shoot is carried about depends upon the local con-
dition of the sea-shore. Sooner or later its career of wanderer is arrested by the
trailing comb-like scales assuming the réle of anchors. As soon as the anchor is
fast, some 2-4 roots develop from the lower internodes of the shoot; these pass
between the teeth of the comb-like anchor, and grow down into the muddy sub-
stratum, thus fixing the offshoot. All this happens at the end of winter. During
the following summer, the shoot, which is about 8 cm. long, and is anchored and
rooted in the mud, again grows up into a stem about a metre high, and next winter
its top again falls off just in the same way. It has already been mentioned (p. 457)
that this strange sea-plant very rarely blossoms or fructifies—a circumstance which
confirms the supposition that the boundless colonies of it round the coasts of
Tasmania owe their origin to the offshoots distributed by the sea currents.

The distribution of offshots by sea-water is a much simpler affair in the Sea-
wracks, Ulvas, and Florideew than in these other water-plants. When the sea is
stirred to its depths by violent storms and the spring-tide is higher than usual
the retreating waves leave any quantity of fragments of these plants behind
them. These have been torn by the raging water from the firmly-fastened
ribbons, nets, and threads below, and are then carried away by the billows. The
water drives them into clefts of the rocky coast or imbeds them in the sand and
mud of the shore, and, wonderful to relate, not a few of them flourish again, granted
of course that they are not speedily removed by subsequent tides and that the
circumstances are otherwise favourable.

Much the same kind of thing happens on the banks of rivers and streams. A
portion of the plant-fragments brought by floods and stranded on the mud of
calm inlets undergoes decomposition. A larger portion remains fresh and living,
sending out roots and vigorous shoots. In the bed of the Danube, in addition to the
abundant creeping shoots of the Reeds (Phragmites) and various Sedges, Bul-
rushes (Scirpus, Typha), broken twigs of Salia fragilis, bits of roots of the Sea
Buckthorn (Hippophae rhamnoides), fragments of the rhizomes of @nanthe Phel-
landrium and Acorus Calamus, leafy twigs and stolons of various species of
Pondweed, Water-Milfoil, and Water Ranunculus (Potamogeton, Myriophyllum,
Ranunculus aquatilis) are all distributed in this way. Sometimes these growths
settle in places where formerly no specimen of the kind had been seen for miles,
and the fact may be easily confirmed that the distribution of their offshoots is
actually brought about by flowing water in a very short time to great distances
and in great abundance.

The distribution of offshoots in little brooks which flow down between Reeds
and Rushes with a moderate fall, and scarcely ever overflow their banks takes
place more quietly. A rapid flow occurs only in the middle of the channel, but
near the bank, and especially in the small inlets, the water is almost as still and
calm as in a closed-in lake. Here in these quiet spots are also to be found floating -

DISPERSAL BY WATER. 809

plants brought by birds; their roots are either not fixed to the ground but sway
about in the water, or they may be altogether absent; examples are, Riccia
fluitans and R. natans, Lemna and Wolfia, and in tropical regions Azolla and
Pistia. All these multiply very rapidly. While they continually branch at one
end, forming spreading lobes and sprouts, they die away on the other, the result
being of course a separation into several pieces, 2.¢. into offshoots. These fragments
spread themselves like a green mosaic over the surface of the water. As the off.
shoots increase in numbers a certain number of them will extend beyond the calm
inlet by the bank into the flowing water in mid-stream. Here they are hurried
away by the current, and it often happens that they travel some distance before
they are again stranded in some calm spot near the bank to form again the starting-
point of a fresh aggregate of offshoots.

Rain-water also plays an important part in the distribution of offshoots, Those
of the widely spread Liverwort, Marchantia polymorpha, so frequently met with
on damp earth, are especially noticeable in this respect. Their development is
represented in fig. 196, p. 23. On the surface of the dark-green leaf-like thallus of
this Liverwort cups arise, at the base of which papillae give origin to plate-like
brood-bodies (gemme, ef. figs. 196% and 196%). Other papills behave differently,
and undergo only slight enlargement. The heads of these latter then swell up
forming a gelatinous mass, and as this swells up it raises the green gemmz higher
and higher out of the bottom of the cup (fig. 196%), At last they get close to the
edge and are washed out of it by the rain. The offshoots of other Liverworts are
also chiefly distributed by rain-water, as for instance the gemme which arise
in the crescent-shaped pockets of Lwnularia, and in the flask-shaped cavities of
Blasia pusilla. The pairs of cells which arise on the upper surface of Aneura
multiida, the single cells which become detached from the edge of the fronds of so
many Liverworts, the multicellular offshoots which are given off by Radula com-
planata so common on the bark of trees, the round cell-plates growing on the edge
of the leaf-like thallus of Metzgeria pubescens, and finally the ball- and dise-shaped
groups of cells which develop on the surface of the leaves of numerous Mosses
(eg. on various species of the genera Leucobrywm, Grimmia, Zygodon, Ortho-
trichum, Barbula, Calymperes). In many of these cases the small offshoots are
detached as well as distributed by the action of rain-water, but in others the loosen-
ing occurs before the rain begins, and in Blasia and Anewra, as well as in
Marchantia, the offshoots are first separated by mucilaginous membranes, and are
thus raised up from their attachment. Not until afterwards are they washed out
and distributed by the falling rain. These small offshoots can of course also be
carried away from their place of origin by strong gusts of wind. Even breathing
strongly on them is sufficient to detach the uppermost gemme of Marchantia, but
in dry air and in dry soil they rapidly shrivel up and perish. The distribution
by currents of air is therefore not attended by success, but the offshoots of the
Liverworts and Mosses washed out by showers of rain immediately begin to grow,
and quickly attain to further development. This mode of distribution plays an

810 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

important part in the covering of tree-trunks with Mosses and Liverworts. A
small patch of Radula, Metzgeria or similar plant having once taken hold, when
a downpour of rain beats upon the trunk quantities of tiny ball- and disc-like
offshoots float away to be caught again by projecting irregularities of the surface;
indeed the rapid covering of old trunks with green carpets and mantles of
Liverworts and Mosses is for the most part effected by rain-water.

It is comparatively seldom that bud- and sprout-shaped offshoots are distri-
buted by rain, But there is one very interesting example of this, viz. the widely-
spread Lesser Celandine (Ranunculus Ficaria), a single plant of which is shown in
fig. 343°, p. 460. In the axils of the foliage-leaves of this plant are developed off-
shoots which have the form of small tubers, and which are not unlike the youngest
stages of small potato-tubers (fig. 343°). When the leaves and stalk of the Lesser
Celandine begin to turn yellow and wither in the early summer, the tubers break
away from the stem and fall to the ground. There they usually escape observation,
since they are hidden by the yellowing foliage; but should there come a heavy
storm of rain the withered leaves are pressed down on to the soil by the force of the
rain-drops, and the scattered tubers become visible. Sometimes the impact of the
falling rain-drops hastens the detachment of the tubers from the mother-plant.
When the rain is so heavy that the water flows away in the form of small rivulets,
the loose tubers are washed off in abundance. A sudden downpour of rain in a
region abundantly overgrown with Lesser Celandine is sufficient to float away
numbers of the tubers, and heap them up on the borders of irrigation channels
when the rain disperses. In such places the quantity of tubers which have floated
together is often so large that one can hardly gather them in one’s hands. In this
way arose the idea that the tubers had fallen from heaven with the rain, and the
myth of a rain of potatoes.

The small tubers which arise in the axils of the leaves of Gagea bulbifera
(ef. fig. 3431, p. 460), a plant growing on the steppes of Southern Russia, are distri-
buted by rain-water just like those of the Lesser Celandine. This brings us to the
question of the much-discussed manna-rain in steppes and deserts, which in reality
is nothing but the distribution of the offshoots of a Lichen, viz. the Manna-lichen.
This Lichen, which was termed Lichen esculentus by the older Botanists, but in
recent times has been referred to the genera Urceolaria, Lecanora, Chlorangium,
and Spherothallia, and which apparently consists of three species, viz. Lecanora
esculenta, L. desertorwm, and L. Jussufit, is spread over an enormous region in
south-west Asia, and extends as far as the south-east of Europe and the north of
Africa. This Lichen is met with in the neighbourhood of Constantinople, in the
Crimea and Caucasus, in Persia (whence the illustration at page 695), also in
Kurdistan, Arabia, and the Anatolian high land from Bulgar Dagh in the Taurus
(where it is very often met with at a height of 2700 metres above the sea), and
finally in the Sahara and the deserts of Algeria. It first forms thick wrinkled and
warted crusts on the stones, preferably on small fragments of limestone lying about;
the outer colour of the crust is a grayish yellow, while on breaking it appears as

DISPERSAL BY WATER, 811

white as a crushed grain of corn. As they get older the crusts become rent, and
separate either partially or wholly from their substratum. When they first become.
loosened the edges of the detached portion become somewhat rolled back. The roll-
ing then continues, and ultimately the loosened piece forms an elliptical or spherical
warted body with a very much contracted central cavity. Small stones are some-
times imprisoned in this way within the cavity of the sphere, in which case the
weight of the loose Lichen is correspondingly increased, but as a rule the hole is
filled with air, and when dried the pieces weigh very little. Ten loose pieces of
Manna-lichen, each as large as a hazel-nut, weighed 3°36 grams, and the weight of
a single piece therefore was on an average only 84 grams. It is easy to see that
the loose portions will be rolled about by the wind, and that a storm will sometimes
sweep them up from the ground and carry them hither and thither through the air.
This method of distribution appears to be the prevailing one in regions where the
supply of water is not abundant in the rainy season, and where violent storms rage
from time to time. That this is so is confirmed by the circumstance that the Manna-
lichen after the storms lies chiefly piled up behind the low bushes and undergrowth,
we. just where the force of the storm has been to some extent broken, and where the
shifting sand has been heaped up into little hillocks. Where a period of heavy
rains succeeds the long dry summer, however, and where such a quantity of water
falls on the parched land that it cannot all be absorbed, some of the rain collects
into small rivulets.) These carry away with them everything which is movable
and capable of floating. The turbid rivulets flow down over the inclined soil to the
lowest parts of the country and there unite into larger streams, or if it can find no
outlet the water remains for some time in the hollows as small pools and puddles,
and deposits there the mud and vegetable débris it has carried with it. The latter
is more especially the case on the steppe soil overstrewn with small stones where
between the slight elevations there is a labyrinth of shallow channels and winding
depressions resembling ploughed land. In such regions the Manna-lichen is chiefly
washed into the depressions by the rain-water, and in some years in such quantity
that they form heaps a span high, and a single man can in a day collect 4-6
kilograms (about 12,000-20,000 pieces, varying in size from a pea to a hazel-nut).
This is especially the case in the steppe region and in the high lands of South-west
Asia, where the Manna-lichen is used as a substitute for corn in years of famine—
being ground in the same way and baked into a species of bread. That the rain-
water is the agent which transports the Lichen in these regions is beyond doubt,
because the pieces heaped up in the hollows are not in the least rubbed on their
outer surfaces as would certainly be the case if they had been rolled and dragged
even for only a short distance over stony ground. It is also remarkable that
all the great so-called rains of manna, of which news has come from the East
to Europe, especially those of the years 1824, 1828, 1841, 1846, 1863, and 1864,
occurred at the beginning of the year between January and March, de. at the time
of the heaviest rains. When we remember that the inhabitants of the district
actually thought that the manna had fallen from heaven, and quite overlooked the

812 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS,

fact that this vegetable structure grew and developed (although only in isolated
patches and principally as crusts on stones) in the immediate neighbourhood of the
spots where they collected it, we need not be surprised at the conclusion of our own
peasants who thought the tubers of the Lesser Celandine had fallen with the rain
from heaven, It should be mentioned that the manna sent to the Israelites on
their journey out of Egypt to the Holy Land is identical with the Lichen described
here and figured on page 695, and the older view that the manna of the desert
was the sap of a Tamarisk (Tamaria gallica mannifera) exuded under the influence
of a parasite is without any foundation.

Spores take the first place among the reproductive bodies which are distributed
by wind. Many Ascomycetes develop some of their spores by abstriction from the
free ends of special hyphe. These rise up into the air from the substratum, which
is permeated or covered by the mycelium. In this way the separated but loosely-
adhering spores can be carried away by the slightest atmospheric movement. In
the Moulds known as Aspergillus and Penicillium, whole series of spores are cut
off from the end of each hypha (see figs. 19345 ® 9, p, 18), and as they are crowded
closely together a single breeze carries off innumerable quantities of spores. By
breathing only lightly on the small forest-like colonies of supports the spores are
whirled as dust into the air, and as they are extremely light they not only remain a
long time suspended in it, but even in perfectly still air are carried sometimes up,
sometimes down, by the currents due to slight differences of temperature, again
being carried horizontally or whirled along until at last they settle, and become the
starting-point of a new Mould formation. The spores abstricted from the ends of
the so-called sterigmata in the Hymenomyecetes (see figs. 389 and 3907) may also be
detached and carried away by wind, but apparently most of the spores in these
Fungi separate spontaneously in calm air and fall to the ground, covering it with a
delicate layer of dust, to be afterwards carried away from this resting-place by
breezes.

The spores of Ustilaginese and those in the ecidia of Uredinez (see p. 686) are
at first covered with delicate membranes and sometimes inclosed in special receptacles.
As soon as they are mature they form a powdery mass, which bursts through the
covering membrane, and the now exposed spores are blown away as dust by the
wind. If they have developed in deep receptacles shaking is necessary before they
can be blown away. The spores then fall from the mouth of the receptacle into the
currents of air. In many Myxomycetes and Gasteromycetes (see fig. 3672, p. 618,
and fig. 391°, p. 690) delicate twisted threads called the capillitium are developed
simultaneously with the spores. The web of threads with the spores between them
is inclosed in a membrane (see fig. 4491), When this membrane bursts at maturity
and the receptacle is thrown open only the spores in the immediate neighbourhood
of the opening can be blown away by the wind, the deeper ones being held back by
the capillitium. The lower layers of the capillitium are then raised by the action
of dry winds, and thus quantities of new spores are continually carried from below
up to the opening. In this way it happens that the spores of these plants are only

DISPERSAL BY WIND, 813

distributed in small detachments, and only at a suitable time, i.e. when a dry wind
is blowing. A similar contrivance is exhibited by the Muscines in the Mar-
chantiaces, Anthocerotacess, and Jungermanniacesz. Peculiar filamentous, very
hygroscopic cells with spiral bands of thickening on the cell-wall, are found with
the spores in the receptacles of these plants (see p. 696). These have been called
elaters, because it was thought that their movements caused the ejection of the
spores. Their significance, however, rather lies in the fact that they serve to hold
the spores together after the opening of the receptacle, and only expose them by
degrees to the wind. They also help to burst open the receptacles, but that hardly
concerns us just now.

Only three of the most striking of the
varied contrivances for spore distribution by
wind in Mosses (which are destitute of elaters)
will be here described. First, those which are
observed in the Andremaceze (see figs. 4501 and
450%). Here the capsule opens by four longi-
tudinal clefts which, however, do not extend
quite to the free end, and the four pieces into
which the wall is thus divided may be com-
pared to the staves of a barrel joined together
at the top. In damp weather they become
approximated, so that the clefts are closed (fig.
4501). In dry weather the valves become
arched, the clefts widen, and the spores may be

Fig. 449.—Trichia clavata.

1 The membrane of the sporangium has burst, and

blown out from the interior of the capsule by the capillitium has bulged out raising up the
. 2 . . : spores embedded between its threads and expos-
the dry wind (fig. 450 3 The distribution of ing them to the wind; x20. 2 Threads of the

capillitium with the spores lying between them;
X 250.

the spores is effected quite differently in the
Polytrichums, one species of which is illustrated
in figs. 450345678 After the roof (operculum) which formerly surmounted the cap-
sule has fallen off a delicate whitish membrane comes into view, which is held fast by
the points of numerous sharp teeth, and is stretched like the skin of a drum over
the mouth of the capsule with its annulus. If rain and dew moisten the Moss the
teeth are seen to be much bent inwards, the membrane lying upon the annulus, and
completely closing the receptacle (fig. 450° and 450"). But in dry air, especially
when a dry wind is blowing, the teeth turn rather outwards, raising the membrane
above the annulus, and thus small holes are left between the teeth through which
the spores can escape (figs. 450° and 450%), The same dry wind which causes the
alteration in the position of the teeth now shakes the spores out of the capsule,
which is borne on an elastic seta. Grimmia ovata, one of the Bryacezx (see
figs. 450° and 4501), may be taken as the type of a third contrivance for ex-
posing the matured spores to the wind in dry weather, retaining them in the
receptacle when it is damp and protecting them there from the injurious effects of
_moisture. The circular mouth of the pipe-bowl-shaped receptacle is furnished with

814 HE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

teeth, each of which terminates in a free point. The tissue of these teeth is hygro-
scopic, and their direction and position alter to a surprising extent according to the
degree of humidity of the air. In damp weather the teeth are so close together
that they completely shut the capsule (fig. 450°), but in dry weather they bend
outwards (fig. 4501), and the spores are shaken out of the capsule and scattered by
the wind.

We shall have to describe presently how the sporangia of most Ferns dehisce

7
AC
\~

Oo

WH
<< i
ea .
IA AK

Fig. 450.—Dispersal of spores by wind.

1 Spore-capsule of an Andreea in damp weather. 2 The same in dry weather. 8 Spore-capsule of a Polytrichum in damp
weather. 4In dry weather. 5 The spore-capsule of a Polytrichum, the edge of the mouth beset with teeth and covered
with a membrane, in damp weather. 6In dry weather. 7A part of the peristome more highly magnified, in damp weather.
8In dry weather. 9% Spore-capsule of a Grimmia in damp weather. 1°In dry weather. 11 Racemose sporangia of a
Botrychium in damp weather. 12 In dry weather. 18 A single sporangium of this Botrychium enlarged, side and front
view, in damp weather. 14In dry weather. 8, 4, 11 and 12 nat. size; the others enlarged.

suddenly so as to scatter the spores. In such Ferns the sporangia are developed on
the under side of the frond, and this position protects them excellently against any
injury which might befall them from rain or dew. But there are some Ferns whose
sporangia are exposed to both rain and dew, and whose spores are not suddenly
scattered by the bursting of the sporangia. Among others, the Moonwort
(Botrychiwm) may be mentioned. Its branched spike of sporangia is represented in
figs 450" and 450. The elliptical sporangia of the Moonwort open by a trans-
verse slit, but the two valves thus formed only separate in dry weather (figs. 450”

DISPERSAL BY WIND. 815

and 450") when the spores may be shaken out and blown away. As soon as the
sporangia are moistened the two valves immediately shut together (figs. 450" and
4507) and obviously the spores can no longer be shaken out. A similar opening
and shutting of sporangia according to dryness or moisture may also be observed in
the Lycopodiaceae (see fig. 4054, p. 716),

A similar phenomenon may also be observed in the sporangia of the Horse-tails
(see fig. 403 4, p. 712). Here not only the sporangia but the spores themselves present
a very different appearance according as they are dry or damp. The wall of these
spores consists of several layers, of which the outermost splits up spirally to form
two arms which remain joined to the spore at one spot. In dry weather the two
spiral bands, which are arranged in the form of a cross, unroll (see fig. 4511) and
constitute four appendages which afford enough purchase to the wind to enable the
comparatively large and heavy spores to be carried away. If the spores fall on to

Fig. 451.—Spores of the Horse-tail Equisetum Telmateja. : ict

1In dry; 2 in moist condition; x25.

some spot of earth which, on account of its dryness, is not suitable for their
germination the wings remain widely outspread. The next gust of wind raises
them up again and carries them to another place. If, however, the resting-place is
moist, and if the conditions are favourable to the growth of the Equisetwm, the
bands roll up spirally (see fig. 451”). In this way the spores may become fastened
to a projecting object, and if this should not be the case at least the rolling up of
the bands produces a diminution in size, and the spores are not easily again blown
away from a suitable damp resting-place. Another explanation as to the function
of these structures has also been offered, namely, that by means of the repeated
expansions and contractions of these hygroscopic arms the spores are linked together
as it were arm in arm. Further reference to this will be found at p. 713.

The soredia of Lichens must also be mentioned as asexual reproductive bodies
which are distributed in enormous quantities by currents of air. To the naked eye
they look like a floury dust deposited in places on the Lichen thallus. These dusty
masses are built up of green cells, either solitary or in groups, which are wrapped

816 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

round by colourless hyphal threads. They arise in the interior of the Lichen body,
and are ultimately pushed out on the surface by the rupture of the pustules in
which they arise. The wind raises and carries them away, and if they happen to
fall into the cleft of a rock or into the crevices on the bark of a tree they
immediately grow up into a new Lichen body which agrees in every particular
with the parent plant and is itself able to again produce soredia. The genera
Stereocaulon, Evernia, and Pertusaria are especially noted for their abundant
formation of soredia. The shrub-like, branched Stereocaulon coralloides is often so
thickly covered with soredia that the whole Lichen looks as if it had been strewn
with coarse meal, and Evernia furfuracea, growing on the bark of old trees, owes its
name to the fact that it seems to have been overstrewn with meal.

It has already been stated that the multicellular offshoots (gemme or thallidia)
of Mosses and Liverworts may be distributed by wind as well as by rain-water. We
might mention as examples, Aulacomnion androgynum, Calypogeia Trichomanes,
Scapania nemorosa, Jungermannia bicuspidata, and Blasia pusilla, whose offshoots
are borne on special erect supports (see figs. 1961 1617 18 p, 23), or Syrrhopodon
scaber, which grows in Central America, and whose thallidia are formed on the apex
of the leaflets (figs. 19612 814). The Moss Tetraphis pellucida (figs. 196 * ® °), which
grows commonly on rotten tree-trunks in Pine forests in mountainous regions, might
also be mentioned. It develops multicellular disc-shaped gemme at the top of
certain erect shoots. The discs are supported on delicate filamentous stalks and are
embedded in a cup of closely crowded leaflets (figs. 1965%7 8). After the supporting
threads have withered and the small multicellular discs have become detached, a
slight shaking by the wind is sufficient to make the gemme fall out and to scatter
them. The.same breeze which shook the stem now whirls the tiny green dises far
over the forest ground and transports them to other places of attachment where
they continue their development.

In some Mosses whose little leaves are very brittle when dry, for example, in
Campylopus (see fig. 1961), the leaves themselves serve as offshoots. How the
detachment of these leaflets is brought about is to some extent an enigma; appar-
ently they separate and are thrown off spontaneously, not unlike the foliage-leaves
which fall from the branches of trees in autumn. This is immaterial to the question
under consideration here, however. This much is certain, that in the remotest
mountain ravines, and on inaccessible ledges in precipitous places where the dis-
turbance of passing animals is quite impossible, the turf-forming crowded stems of
Campylopus always carry detached and partially split leaflets which adhere loosely
to the support. When after a few dry days a storm rages through the ravines, these
loose leaflets are torn away, and do not again come to rest until they are far distant
from the spot from which they were taken. The offshoots of Mosses composed of
groups of cells, and the last-mentioned detached leaves which function as offshoots,
do not grow up immediately into new Moss-plants, but first of all develop protonema-
like cell-filaments, and it is from these that the young Moss-plants originate.

It also happens that whole Moss-plants with elongated axis, numerous leaves,

DISPERSAL BY WIND. 817

and abundant rhizoids are distributed by wind. This is observed in Mosses of very
different genera (e.g. Leucodon sciuroides, Thuidiwm abietinum, Hypnum rugosum,
Myurella julacea, Conomitrium Julianum, Anectangium Sendtnerianum). The
development of this form of offshoot is shown in figs. 156% and 156", p. 23, in
Leucodon sciwroides, which is common on the bark of old trees. In the angles made
by the leaves with the axis of old shoots, buds first arise which grow into miniature
Moss-shoots. These tiny shoots then become loosened at their base, and push up
towards the top of the leaves supporting them. This happens more especially in
rainy weather. When it is dry their leaflets lie close to the axis, but when saturated
with moisture they stand out and bend backwards, and thus raise themselves out of
the deep niche in which they have hitherto been concealed. Many of these loosened
shoots are without doubt carried away by rain-water, and so transported some
little distance, but most of them are whirled off by the wind, and carried far away
over mountain and valley.

Bud-shaped offshoots, which become detached from the aérial portions of plants,
and whose distribution is effected by wind, are comparatively rare. A remarkable
instance is furnished by the Club-moss Lycopodiwm Selago (see fig. 343%, p. 460).
This plant, which is found in mountainous districts in the Northern Hemisphere
of the Old and New Worlds, forms buds in the axils of its stiff, dark-green leaves,
especially near the top of the shoot, which might, at first sight, be mistaken for
small winged fruits. These buds are so provided with little leaves as to offer a
good purchase to the wind, and by this means they are transported (cf fig. 343°).
The North American Lycopodiwm lucidulum, L. reflecwm, L. Haleakala, L. ser-
ratum, L. erubescens, behave in just the same way as Lycopodium Selago, and
it is not improbable that many other allied species exhibit this kind of offshoot.

Most detached bud-like offshoots, which develop in the axils of foliage-leaves
and bracts on larger plants, ¢.g. on the bulbiferous Coral-wort (Dentaria bulbifera;
see p. 461), can hardly be said to be distributed by wind. They are spherical
or ovate, and not flattened like those of the Club-moss, and they are too cumbrous
for transport on the wings of the wind. And yet the wind plays an important
part in the distribution in such cases. The bulbils are borne on fairly stiff shoots,
and the nature of their attachment is very fragile. Thus, as the shoot rebounds
after the blast, many of the bulbils become detached, and are jerked away to a
considerable distance.

There are three types of offshoots which are jerked from the plant in the above-
mentioned manner. First, those which have the form of closed buds or small bulbs,
and which consist of a very much abbreviated stem or bulb-axis, and a few much-
thickened scale-leaves filled with reserve materials. These are found in the
bulbiferous Coral-wort, which grows commonly in Central European Beech forests,
and has been selected as typical; on the bulbiferous Saxifrage (Saaifraga bulbifera),
widely distributed in meadows in Eastern Europe; on several Lilies (e.g. Lilium
bulbiferum, tigrinum, and lancifolium); and on the Persian Gagea (Gagea Persica),

in the axils of the upper foliage-leaves; on Foucroya gigantea, growing on the
Vou. IT. 102

818 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

Antilles, and above the disc-shaped bracts on the top of the stalk on a considerable
number of species of Allium (e.g. Allium Moly, vineale, oleracewm, carinatum,
arenariwm, Scorodoprasum, sativum). A second type, growing in the axils of bracts
on the upper part of the stem, is shown by Polygonwm bulbiferum and viuiparum,
natives of the far north, and of the Alpine regions of Europe and the Himalayas (see
figs, 452128 45,648), These are not bulb-like structures, but small tubers or corms
with a minute terminal bud projecting like a little horn, and the tissue of the tuber
is abundantly filled with starch and other reserve materials (see figs. 452° and 452”),
The third type is observed in species of the genus Globba, belonging to the
Scitamines, more especially in the East Indian Globba bulbifera and in Globba
coccinea, which grows in Borneo. These rare plants develop offshoots in the axils
of bracts on the uppermost part of the rigid stem. They consist of a small bud,
from whose minute axis a thick, fleshy root filled with reserve materials grows
down, so that in reality the chief part of the offshoot consists of a root-structure.

When the closed bulb-like offshoots, tubers, or buds with thickened roots have
been thrown from the wind-swayed stem they remain unaltered in the spot where
they have found a resting-place through the whole winter, or the whole dry period
of summer. At length, when the most suitable time of year arrives, little
absorbent roots make their appearance (see fig. 452°) at the expense of the stored-
up reserve materials, and these fix the offshoots in the soil and convey fluid
nourishment to them. The axis of the offshoot elongates and grows into a stem,
putting out leaves and forming a new independent plant.

The entire sprouts, which are detached from aérial stems and become offshoots,
can obviously not be transported very far by wind. They are much too heavy, and
offer no suitable hold to the wind, which can only influence them by shaking the
stem on which they are supported, or by rolling them along after they have fallen
to the ground. In the former case the sprout-like offshoots are jerked off, and the
action of the wind is therefore only indirect. Some plants bear side by side on the
same stem tubers with undeveloped buds, and also some whose buds have begun to
grow into sprouts, and have developed green foliage-leaves. These-form a connect-
ing-link between the groups just described and those we are now about to consider.
One of them is the already mentioned viviparous Polygonwm (Polygonum viviparum,
fig. 452), in which it often happens that all possible stages of development occur
close together on a single spike.

In Grasses especially it is often the case that the offshoots when ready to be
detached have the form of developed, leafy sprouts. In the Grasses of the Arctic
flora belonging to the genera Poa, Festuca, and Aira, the formation of leafy sprouts
which become offshoots is so usual that in places the plants bearing offshoots are
more common than those bearing flowers in their panicles. On our high mountains
also there grows a grass (Poa alpina, ef. fig. 3428, p. 455), in which the panicles as
often bear offshoots as flowers. On the plains of Hungary flourishes a species of
Meadow-grass (Poa bulbosa), in which the same thing happens to such an extent
that in the many thousand plants which cover the ground all the panicles develop

DISPERSAL BY WIND. 819

offshoots exclusively. The detachment takes place in different ways in these
“viviparous” Grasses. Usually the sprouts loosen from the erect panicles of the

Fig. 452.—Polygonum viviparum.

1 Entire plant; one spike bears flowers only, the other carries tubers on the lower half and flowers above. 2A whole plant
whose spike bears tubers only. On some of the tubers small foliage-leaves have already developed. 3-8 Fallen tubers in
successive stages of development; nat. size. 9° A fallen tuber magnified. 1° The same in longitudinal section.

swaying haulm, and are scattered by the wind, but sometimes the separation does not
occur until the stem is bent down to the ground with the weight of the crowded
offshoots in the panicle. In this case the offshoots strike root where the panicle

820 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

touches the soil, and the result is that closely-crowded groups of new plants grow
up round it. The same thing may be observed in Chlorophytum comosum, a native
of the Cape often cultivated as a basket plant by gardeners under the name of
Cordyline vivipara. In this plant leafy shoots are very regularly developed in the
floral region instead of flowers, and as these increase in size and become heavier, the
long, comparatively slender and very supple stem which bears them sinks down
so that the sprouts are suspended on a green thread. If the ground below is
suitable the pendent shoots which have meanwhile developed roots may settle
there. If they do not come into contact with any suitable soil they remain a long
time swaying in the air, growing and themselves forming long, thin stalks in their
turn in whose floral region fresh, leafy sprouts with roots arise, and years after
three or four generations of shoots connected together by a slender green stalk may
be seen hanging down for the length of a metre. At length one or other of the
swaying and wind-tossed sprouts strikes firm ground and takes root, separating
itself from the old plant, or it falls like the fruit from a tree and rolls down below
until it finds a place of settlement possibly at a considerable distance from the old
plant.

Among the Rushes also there are many species which develop pendent sprouts.
In one species which is very widely spread over Northern Europe, viz. Juncus
supinus, it is much more usual to find sprout-like offshoots in the floral region than
flowers. In many of the Saxifrages of the far North, viz. in Saaifraga stellaris,
S. nivalis, and 8S. cernua, very reduced shoots with small rosettes of foliage-leaves
are formed on the terminal branches of the floral axis, or bulb-like buds arise in the
axils of the bracts on the upper part of the stalk which, like those of the viviparous
Polygonum, send out green foliage-leaves before they fall or become loosened (see
figs. 8424°34567 p, 455). Sedum villosum, which grows on moors, develops
short, leafy sprouts with thread-like axis in the axils of the stem-leaves. As soon
as the stem begins to wither these sprouts loosen and are carried to a short distance
by gusts of wind. They send out delicate roots as soon as they find a resting-place
and new plants are established.

A very peculiar mode of detachment and distribution of sprout-like offshoots
is found in many species of House-leek (Sempervivum). The Sempervivum
soboliferwm illustrated here may be taken as an example. The thick, fleshy leaves
of this plant are arranged, as in all House-leeks, like rosettes on abbreviated aXes,
and the new rosettes are always laid down as minute buds in the axils of the
rosette-leaves. From these buds proceed thread-like runners, furnished with small
adherent scales, ending in a reduced shoot. The crowded leaves of this reduced
shoot enlarge, forming a small rosette, the leaves being folded so closely together
that the whole structure has a spherical form. For some time the round rosette is
nourished by means of the filamentous runner from the old plant, but afterwards
the runner withers and dries up and the rosette breaks away from it. It is now
quite separated from the parent plant (see fig. 453). A gentle breeze is sufficient
to roll along the small detached balls; and as the House-leeks in question choose

DISPERSAL BY WIND. 821

as their habitat narrow ledges in rocky places, it is inevitable that some of the
separated rosettes should fall over the steep wall, and should not come to rest
till they have travelled a considerable distance from the mother-plant. Roots are
soon developed from the base of the detached rosettes, by which they become fixed
to the substratum. Usually a parent plant produces 2-3 rosettes, but frequently as
many as six, and the neighbourhood of the terraces overgrown with the species
of House-leek figured, and with other allied species (Semperviveum arenariwm,

SS
S SSS SSSS S SAS WW Sx \

Fig. 453.—Sempervivum soboliferum. On the lower step of the rock lie five ball-shaped offshoots which have become detached
from the upper rocky platform and have rolled down. The butterfly and snail are introduced into the picture to show
the true proportions of the offshoots.

S. Neilreichii, 8. hirtum) often looks as if it had been sown with the ball-like
rosettes, which have rolled down,

Sedum dasyphyllum (see fig. 4541), which grows in rocky crevices and in the
niches of old stone walls, develops offshoots partly in the floral and partly in the

foliage region. In the floral region the offshoots originate by the metamorphosis of .

floral-leaves into foliage. Instead of flowers there are small rosettes (fig. 454°) of
thick, ovate, green scales, like those which take the place of flowers in Saxifraga
nivalis and S. cernua (ef. p. 455). These rosettes in the autumn break away from
the flower-stalks, and behave just like those of Sempervivum. In the foliage region
the offshoots arise in three ways. In the axils of the uppermost leaves there is
formed a bud which is hardly perceptible to the naked eye. It is embedded in the

822 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

shallow depression on the upper side of the thick leaf, and possesses 2-3 leaflets
about ‘5 mm. in diameter (fig. 4542). In the axils of the lower foliage-leaves short
sprouts are formed, whose axes are furnished with fairly large crowded rosette-
shaped leaves (fig. 454°). In the axils of the lowest arise rudimentary sprouts,
with an elongated thread-like axis bearing 8-14 thickly-crowded leaflets at its end
(fig. 4544). As soon as the stem carrying the flowers begins to wither, the foliage-
leaves and the buds or sprouts in their axils loosen from it and fall to the ground.
The succulent, very turgid, almost hemispherical leaves are comparatively heavy,
and if the spot where they first fall is sloping they do not lie still, but roll down
until they are caught by some pro-
jecting ledge, or a mossy cushion,
or arrive on level ground. Since
they carry with them the buds and
sprouts formed in their axils, they
to a certain extent function as a
means of transport. As soon as the
offshoots come to rest, they develop
rootlets at their base at the expense
of the reserve materials of the de-
tached succulent leaf. Rootlets are
often formed even while the leaves
are still adhering to the decaying
stem. It is worthy of note that
the aqueous tissue of the fallen
leaves also plays a part in the
S establishment of these offshoots. If

Fig. 454.—The formation of offshoots in Sedum dasyphyllum. the spot where they have come to
‘Mat iferent teres nthe stom in the arie theta, tom, Te’ FS exceptionally dry, as is

shoots from the floral region. usually the case in places where

Sedum dasyphyllum grows, the
supporting leaf may for a long time provide the water necessary for the mainten-
ance of the offshoot, and so protect it from perishing.

The formation of sprout-like offshoots is very remarkable in the Kleinias,
natives of the Cape, which belong to the Composite. Some species of this genus,
viz. Kleinia neriifolia and K. articulata, remind one very much in their appear-
ance of certain Cacti. The fleshy, much-thickened cylindrical branches are connected
with one another by thin strands, and the whole plant looks as if it had been
constricted at intervals by ligatures. The strands joining the heavy cylindrical
branches break at the slightest pressure, and the upper shoots especially may be
broken offeven by a violent gust of wind. The result of the fracture at the constricted
places, however, is that the branches fall to the ground. If the plant grows on a
slope, the fallen cylindrical shoots roll down until they are stopped by a projecting
stone or some other obstacle. When they come to rest they develop numerous roots

DISPERSAL BY WIND, 823

where they touch the ground, and at the same time send up new lateral branches
from the opposite side, as shown in fig. 455. It should be mentioned that in KX.
articulata the roots often begin to develop before the branches have broken and

fallen off, always appearing on the side of the shoot which is turned towards the
soil. This also is shown in the figure.

Fig. 455.—The formation of offshoots in Kleinia articulata. L ofa

In all these instances the offshoots are detached by the force of the wind.
Another method by means of which the same end is attained depends on the
hygroscopic properties of the tissues concerned, and on the alternate swelling and
contraction from this cause. Several Fungi of the group Peronosporex, among others
the unwelcome Potato-disease Fungus, Phytophthora infestans, multiply by spores
formed on delicate hyphal threads, which are protruded from the stomata of the

824 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

host plant. These hyphal threads bifurcate, and the end of each branch swells up
into a spore. The supporting hyphal branch then grows out again below each
spore, elongates, and extends upwards, and pushes the spore on one side. The
result of this oft-repeated process is a structure which resembles a small much-
branched tree, with egg-shaped fruits hanging from the boughs. The hyphal
branches, on which the spores are set like fruits, are cylindrical, stiff, and turgid in
damp air, but in dry air, especially when they are ripening, they become ribbon-like
and spirally twisted so as to resemble cotton-cells. They are extremely hygroscopic,
and the slightest change in the humidity of the surrounding air is enough to
increase or diminish their spiral torsion. Even mere breathing on them produces
an alteration in the twisting, and if a rapid and marked alteration occurs in the
hygroscopic condition of the environment, the branches with their hanging spores
are whirled hither and thither, and the spores, which are only attached but slightly,
are scattered in all directions. This cannot of course be seen except under unusually
favourable circumstances, on account of the minuteness of the spores.

The shedding of the spores can be observed with the naked eye in the Mould
Pilobolus cristallinus, one of the Mucorines, shown in figs. 4561 and 456%. The
mycelium of this Mould consists of a colourless, much-branched tube, and grows on
the excrement of horses and other mammals. Enlargements arise on the mycelium,
and from each is produced a sporangial mechanism composed of two parts, a colour-
less, barrel-shaped, stalk-cell and a dark head. The latter contains a colourless
jelly, which swells up in water, together with numerous spores, and is to be regarded
as a sporangium. Its wall is covered with calcium oxalate, so that its elasticity is
completely lost and it becomes brittle. The cell-wall of the barrel-like swollen
stalk, however, remains soft and elastic. At the junction of the dark sporangium
with its colourless stalk a circular layer of separation is formed. When the
turgidity of the sporophore increases in consequence of the absorption of water
from the mycelium the tension at last becomes so great that it causes a rupture
round the circular line mentioned. At the same moment, however, the elastic wall
of the part of the sporophore immediately below contracts, and the fluid contents
are pushed out with great force. The push is transmitted to the dark sporangium
above the split, and both the fluid contents of the club-shaped support and the
entire sporangium are thrown off (see fig. 456). The force of the explosion is so
considerable that the dark mass is raised about a metre in height. The whole
process, which, as we have said, may be seen with the naked eye, usually occupies
18-20 hours. The development of the mechanism begins at mid-day; during the
night the spores are formed in the vesicle, and the next morning the explosion
occurs as soon as daylight appears.

A no less interesting spectacle is afforded by the scattering of the unicellular off-
shoots, 7.e, conidia, in species of the genera Empusa and Entomophthora. These live
on the dead bodies of caterpillars, flies, aphides, and other insects, the commonest
and best known being Empusa muscc, which lives on the common house-fly. When
a conidium of this Hmpusa falls on the body of the fly it puts out a tube which pene-

DISPERSAL BY EXPULSIVE MECHANISMS, 825

trates into the body-cavity, and there it divides up repeatedly, forming numerous
cells throughout the body. The infected fly, sickening under the injurious influence
of the Fungus and almost at the point of death, seeks for some quiet spot in which
to die. It frequently chooses for its last resting-place a window pane, in which
case it is possible to thoroughly investigate the further development of the Fungus.
After the death of the fly the round cells of the Empusa, hitherto hidden in the
body-cavity, grow out into long tubes which pierce the skin of the fly’s corpse and
appear as short club-shaped structures on the surface. A single egg-shaped conidium

Fig. 456.—Distribution of spores by expulsive mechanisms.

1 Pilobolus cristallinus before the sporangium breaks away. 2 The same at the moment when the sporangium is thrown
off. 3 Sporangium of Nephrodium Filix-mas closed. 4 and 5 The same in the act of splitting and scattering the spores.
6 Spheerobolus stellatus at the moment when the balls filled with spores are thrown off. 7 Peziza aurantia. 8 Longi-
tudinal section through this Peziza, The spores are escaping from two of the asci. All the figures magnified

is then cut off from each club-like end of the tube, and this is thrown off in exactly
the same way as the sporangium of Pilobolus (cf. fig. 3837, p. 672). Here, too, a
place is formed for the splitting, and here again the mucilaginous contents are—
thrown off simultaneously with the conidium by the sudden contraction of the club-
shaped end of the tube, and the conidium is thus always surrounded by a gelatinous
adhesive mass (fig. 383°). The distance of the projection may be as much as 2-3 em.,
which, considering the extraordinary minuteness of the conidia, is proof of great
power. The dead fly then appears to be surrounded by a veritable halo of detached
conidia which are firmly attached to the substratum (fig. 883°), This is to be accounted
for by the fact that, asjalready stated, a part of the sticky mucilaginous contents of
the club-shaped end of the tube are thrown out with the conidia. This serves as
an adhesive material, and causes the conidia to adhere particularly firmly to glass
window panes. If a living fly which happens to be near is struck by the projected

826 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

conidia, they stick to it so firmly that it cannot succeed in getting rid of them or
freeing itself in spite of all its attempts. Each adhering conidium then again sends
a tube into the body-cavity of the fly, and the development is repeated in the way
just described. The same thing happens in Entomophthora radicans, which lives on
the caterpillar of the Common White butterfly (Pieris Brassice). It is represented
in figs. 38342345, p. 672). Tufts of delicate thread-like hyphe come out of the body
of the caterpillar for the purpose of forming conidia (fig. 383°). These gradually
form a thick web round the dying caterpillar, and at a cursory glance one might
think it had woven its covering and changed into a chrysalis (fig. 383°). The tubes,
looking like fine threads, unlike those of Hmpusa, are here much-branched, and
actual tufts of hyphe arise from whose ultimate somewhat swollen ends the long,
sticky conidia are abstricted and scattered (figs. 383 * and 383°),

The scattering of the spores from the asci of Ascomycetes takes place in a
characteristic manner. They are developed in groups of 2, 4, 8, 16, or 32 in the
tubular asci, and numerous thread-like hyphal ends, the so-called paraphyses, occur
between the asci (see fig. 456%). In addition to the spores the asci contain proto-
plasm and cell-sap, and are considerably distended by the large amount of the
latter. As the dilatation increases the asci burst, and their cell-wall, which is at a
high tension, exercises a powerful pressure on the cell-contents, which are extruded
with great force. The place where the rupture of the wall of the ascus occurs is
determined beforehand, so that the extrusion of the cell-contents and spores always
takes place in the same way. In many species the top part of the ascus-wall is
raised like a lid, in others a transverse splitting occurs, and in others again the
spores are ejected through a small circular hole. A slight shake or a dry breeze is
quite enough to cause the ejection, and in Spatularia flavida, for example (figured
on p. 791), or in Peziza awrantia (see fig. 4567), it is easy to observe how small
clouds of extruded spores rise from the surface of the fructification as soon as these
Fungi are brought from a damp place into a dry atmosphere, or when a dry wind
-blows over them. In some species of Ascobolus, minute black or waxen yellow
Fungi living on the excrement of animals, the spores are not only ejected, but the
turgidity of the tissue surrounding the tubes is so great that the whole tubular
layer is extruded with the spores.

Some Gasteromycetes have special contrivances for scattering the spores. In
species of the genus Geaster (see figs, 391 * and 391°, p. 690) the threads of the capil-
litium and the spores imbedded between them develop within a tough, leathery,
bladder-like envelope which separates into two layers when the spores are ripe.
The inner layer has the form of a bladder, and opens only at a spot at the apex.
The outer layer, on the other hand, splits into 4-12 radiating lobes. The position of
the lobes alters remarkably according to the hygroscopic condition of the atmo-
sphere. In damp weather they fold together over the vesicle, but in dry weather,
especially in sunshine and when a dry wind is blowing, they bend back so forcibly
that some of the spores are shaken from the mouth of the vesicle. Travellers in
Central America tell us of the gigantic Puff-balls which literally explode on being

DISPERSAL BY ANIMALS, 827

shaken, sending such quantities of reddish spores into the air that it is impossible to
breathe in their vicinity. In Europe a minute Puff-ball, Spherobolus stellatus
(fig. 456°), grows on decaying stems, leaves, &c. The wall of the fruit divides,
as in Geaster, into two distinct layers: one remains closed and assumes the form of
a ball, but the outer one when the spores are ripe divides by radiating clefts into
several lobes. These bend back rapidly on drying, and as the central portion
round which the lobes are placed becomes strongly arched upwards, at the same
time the ball containing the spores is shot out with considerable force.

The dissemination of spores in some of the Ferns is illustrated in figs. 4563 45,
Sporangia are developed on the under surface of the frond, where they are arranged
in various ways. Those of the Nephrodiwm Filix-mas, which is here selected as a
type, consist of a stalk and a flattened bi-convex vesicle. Round the latter runs a
ring of darker-coloured cells, whose side-walls are much thickened, while their
outer walls remain thin and delicate. When the sporangium is ripe its bursting is
brought about by the contraction of the cells of the ring.

With regard to the distribution of offshoots by animals we may distinguish two
classes, those in which the offshoots are first conveyed to the animals by special
disseminating mechanisms, so that two methods of distribution are combined, and,
secondly, those in which animals alone effect the transport of the offshoots from
one place to another. We have already spoken repeatedly of the former class. Of
the latter the distribution of spores by food-seeking animals is the first to be
considered. The Pyrenomycetous Fungus known as the Ergot of Rye (Claviceps
purpurea) is a well-known instance. The thick web of hyphal threads which
invests the ovaries of the Rye is penetrated by labyrinthine passages, whose walls
are formed by the ends of hyphal threads arranged in rows and tufts (see fig. 386 ?,
p. 680). Spherical spores are abjointed from these somewhat club-shaped ends.
Simultaneously with this abjunction the outer layer of the cell-wall of both spores
and hyphex forms a sugary fluid by the absorption of water and subsequent breaking
down. This fills the winding passages, and the innumerable abjointed spores are im-
bedded in it. The sweet-tasting fluid gradually collects into drops on the exterior,
and even comes into view on the spikes of Rye between the glumes which surround
the infected ovaries. This is the “honeydew” by which the presence of the parasitic
Claviceps in the interior of the spike is recognized, and which is viewed with some
apprehension by the farmer. Insects, especially wasps and flies, eagerly seek out
these springs of sweet fluid and suck and lick up the juice, which is crowded with
numberless spores. It is therefore inevitable that small quantities of spores should
stick and remain hanging to portions of their bodies, and when they fly to the
spikes of other Rye-plants the spores are easily rubbed off, and in a very short
time may again grow up into a mycelium involving the ovaries there.

A similar phenomenon may be observed in the Phalloidex, belonging to the
Gasteromycetes, of which the best known species, the Stink-horn Fungus (Phallus
impudicus), may be taken as an example. The cap, borne on a white cylindrical
and spongy stalk, is bell-shaped and covered with a greenish-black viscous fluid in

828 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

which numerous spores are imbedded. This fluid gives off a far-reaching carrion
smell which allures many insects, especially carrion-flies. The fact that the fluid
contains sugar which serves as nourishment for the insects also contributes to the
allurement. A fly which alights on the cap of the Stink-horn cannot leave it
without spores adhering to its whole body. Some of them may, perhaps, fall off
while it is flying away, but the majority will not be brushed off until it again
alights and cleanses itself from the uncomfortable appendages (cf. also p. 691).

It is well known that the fleshy fructifications of Hymenomycetes provide food
for numerous insect-larve. Frequently as soon as the receptacles appear above the
soil the flesh of the stalk and cap are riddled by passages in which live the larvee
of various gnats and beetles. These leave their dwellings before the decay and
decomposition of the Fungi set in, and enter the chrysalis stage in the ground. In
this way numerous spores which have adhered to the animals are carried away
and disseminated. The spores of various Fungi, especially of the Hymenomycetes
and Truffles, are without doubt distributed by animals which eat the fleshy spore-
bearing portions. The spores pass unharmed through the alimentary canal and
then germinate in the deposited excrement. Earthworms and swine in particular
seem to take part in this distribution.

The dissemination of detached bud- and shoot-like offshoots is comparatively
seldom effected by animals. Of the cases known the following are the most note-
worthy. First, where the offshoots are taken up as food by animals, but are
again got rid of in an undigested condition, and grow up into new plants in the
place where they have been deposited. This has certainly been observed in Poly-
gonum viviparum, which grows commonly in the far North and on the high
mountains of Central Europe (see fig. 452). The bulbils of these plants are a dainty
morsel to ptarmigan, and are eagerly sought for by them. The ptarmigan seizes
the lower half of the spike of the Polygonum with its beak, and by a quick
movement of its neck passes the bill the whole length of the spike, and so puts
dozens of bulbils at a time into its crop. Numerous observations have shown that
the bulbils of Polygonum viviparum and cranberries are the commonest food
found in the crops of ptarmigan shot on the Alps, and I also always found these
bulbils in great quantity in the crops of Norwegian ptarmigan. The portion which
passes from the crop into the muscular gizzard is of course crushed and digested,
but it has often been noticed that part of the food so greedily swallowed by the
ptarmigan is thrown up again, and this is particularly the case with the bulbils
when they have been taken in excess. When thus extruded, they have the power
of further development; far from being destroyed, they grow up very rapidly into
new plants, and as the places where the superfluous food is thrown out are always
at some distance from the spot where the ptarmigan obtained the bulbils, this
process is really a mode of distributing the Polygonum viviparum.

The second method of distributing detached offshoots by animals is effected by
means of barbed bristles and hairs, such as are represented in fig. 457, in the
Mamillarias (Mamillaria placostigma and gracilis) of the high mountains of Mexico.

DISPERSAL BY ANIMALS. 829

Here some of the spherical, closely-crowded lateral shoots growing from the old
plant loosen spontaneously and fall to the ground; others again remain in situ
but adhere very slightly, so that a passing contact or a gentle touch is enough to
complete the separation from the old plant. Now bristles are formed at the top
of each papilla of these Mamillarias, some of which end in barbs, so that the
spherical shoots resemble burs. They adhere just like burs to the hairy paws or
fur of grazing animals, which carry them away unconsciously. Afterwards

srl

eee
Fig. 457.—Distribution of detached sprout-like offshoots by means of animals. saci:

1 Mamillaria placostigma, 2% Mamillaria gracilis.

the animals when resting seek to rid themselves of the inconvenient appendages,
brushing them off and leaving them behind on the ground. Here they may strike
root and grow up into new plants.

The third method of distribution of sprout-like offshoots by animals is seen in
aquatic plants, which fasten either entirely or in fragments to passing water-birds.
Certain species, which very rarely blossom or form fruit, but nevertheless occur in
innumerable widely distant spots and often appear unexpectedly in newly-formed
ponds, in artificial lakes, and in other waters, are for the most part distributed by
water-birds. Some of these water-plants, e.g. the Frogbit and Bladderwort (Hydro-
charis and Utricularia), develop peculiar slimy coverings round their buds, which

830 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

cause them to stick to the feathers of birds which come in contact with them as
they swim by. Others, such as the small Duckweeds (Lemna minor, gibba,
polyrrhiza), hang by their long, somewhat twisted, floating roots, and many
filamentous Alge, Aldrovandia, the delicate Riccias (Riccia natans and fluitans),
the Ivy-leaved Duckweed (Lemna trisulca), &c., become attached in their entirety
to the coot and duck swimming in the ponds and lakes. These fly away with them,
but as soon as they again enter other water the adhering plants fall off or are
cleaned off by the birds, and in this way they are distributed quite fresh and living
over great distances. We might also mention in this connection the peculiar distri-
bution of Ulvas, Floridez, and Sea-wracks by means of crabs, which was described
at vol. i. p. 77.

We will only allude in passing to the fact that many economic plants are propa-
gated and distributed by offshoots to a very great extent by man. Bananas whose
fruits contain no fertile seeds, Potatoes, Artichokes, and many other tuberous and
bulbous plants are continually multiplied by the help of slips, tubers, bulbs, &e.
The intentional artificial propagation by offshoots has of course no apparent
influence on the development of a natural method of distribution in such species.
Although planted and cultivated in large quantities they do not become naturalized;
and if it were not for the artificial maintenance and propagation by offshoots they
would soon vanish again from such places, leaving no trace behind. This is, how-
ever, not the case with the unintentional distribution of offshoots of certain plants
by man. The keels and bottoms of ships journeying over wide seas become, like
the stakes and buoys of the harbour and the sea-walls and rocks of the shore, quite
overgrown with sea-weeds. If these are removed by chance or intentionally from
their substratum they do not necessarily perish. They may remain alive in the sea-
water, and under favourable conditions may attach themselves to some other firm
spot of ground. In this way plants may be transmitted from one coast to another
over very wide distances. Another unintentional distribution of plant-offshoots by
man occurs on cultivated ground in vineyards, fields, and gardens. By ploughing,
digging, and throwing up the soil the bulbous or tuberous offshoots embedded in the
ground undergo a change of position. The offshoots of certain plants may in this
way be distributed so uniformly over a whole field by spade and ploughshare in the
course of a year that it almost looks as if they had been purposely planted there.
It is curious on journeying through the vine-planted districts of Northern Italy to
see one of two adjacent vineyards abundantly covered with wild Tulips, while not
one is visible in the other. In Central Europe the same thing happens with the
Gageas (Gagea arvensis, G. stenopetala) growing in the fields, and with the tuber-
forming Earth-nut pea (Lathyrus tuberosus). One field looks as if it had been sown
with Gageas and yet its neighbour is completely devoid of them. On the Giinsel-
hohe in the Lower Austrian Erlafthal I once saw a rectangular ploughed field over-
grown from one end to the other with plants of the Bulbiferous Lily (Lilium bul-
biferum), while only isolated specimens of this plant could be seen in the adjoining
fields. There is no doubt that here the bulbils thrown on to the ground from the

DISPERSAL BY ROOT-SHORTENING. 831

leaf-axils of a few plants had been distributed equally by ploughing over the whole
field, although this distribution had certainly not been intended by the ploughman,

It would of course be a mistake to explain the uniform distribution of bulbous
plants over a large stretch of land exclusively by the ploughing and overturning of
clods of soil full of bulb-like offshoots. In many instances the distribution of such
offshoots is also produced by the pulling action of the roots. This process is so
remarkable that we must describe it somewhat in detail. The multiplication of
subterranean bulbs is known to take place by the formation of buds in the axils of the
scale-leaves, and these, in the course of a few months, themselves grow up into small
bulbs. When mature, they may form the termination of a slender shoot which,
of course, never attains any considerable length, but which in many cases is thread-
like, as shown in Muscari racemosum (fig. 4441). The small bulbs are pushed by
this thread-like shoot out of the region of the protecting scale-leaf near the old
bulb, and there they develop long root-fibres in abundance. In other instances the
shoots remain extremely short, and the small bulbs are not pushed out, but the
protective scale-leaf, in whose axil they originated, decomposes, and they send out
their roots through the decomposing tissue into the surrounding soil. In both cases.
they become detached at the end of the vegetative period in which they originated;
they are then no longer connected with the old bulb, but are quite independent.
Many species form only one bud in the axil of a bulb-scale, others a whole series
which all grow up into bulbs; in the latter case the old bulb in the autumn is.
surrounded by a whole family of small young bulbs. There is a species of Garlic
called Allium pater-familias whose old bulb gives rise to about a hundred young
ones in a year. It is impossible for so many to develop properly when closely
crowded together round the plant from which they sprang; mutual pressure would
be unavoidable in their further growth, and if next year each of these bulbs should
in its turn form new offshoots, and again become the centre of young bulbs, it.
would become imperatively necessary to make room, and to thin and separate the
dense crowd. Since all the bulbs are placed with their apices pointing upwards.
they cannot be moved apart by the elongation of their stems; the mutual pressure
of neighbouring bulbs as they enlarge would certainly cause a trifling displacement,
but this would not prove an efficient remedy. The remarkable pull of the roots,
which was described in vol. i. p. 768, now comes into play. Only a few of the roots
arising from the base of a young bulb strike downwards; by far the greater number
grow out at a right angle to the axis of the bulb in a direction parallel with the
surface of the soil (see fig. 4441). When these very long roots have stopped grow-
ing they contract, and thus draw the young bulb to which they belong away from
the old one. The young bulbs now form a wide open wreath round the old one
(which has meanwhile disintegrated), and thus obtain sufficient room for further
development. ‘This happens not only in the Muscari described, but also in
Ornithogalum nutans, Tulipa sylvestris, and indeed in quite a number of bulbous.
plants. Since this process is repeated annually a fairly wide area of soil may in
the course of years be covered with the bulbs in spite of the slight distance through

832 THE DISTRIBUTION OF SPECIES BY OFFSHOOTS.

which they have been shifted under the ground. Some soil containing bulbs of
Tulipa sylvestris was once put in a garden in Vienna in the middle of a grass plot
shaded by Maple-trees. As the grass was mowed every year before the flowers
opened there was no formation of seed, and the Tulips could only multiply by
offshoots. After about 20 years the lawn was covered with Tulip-leaves, which
arose from subterranean bulbs occupying an area 10 paces in diameter. Thus in
the time mentioned the bulbs had spread for about 5 paces in all directions, in
consequence of the pull of the contracting roots. It is more than probable that the
offshoots of many perennial plants with erect stem and napiform or tuberous roots,
e.g. the blue-flowered species of the Monkshood (Aconitum Napellus, A. Ne eubergense,
A. variegatum) undergo a change of position by the pull of their horizontal root-
fibres; and that the clustered arrangement of these plants is the result of the root-pull.

A review of the very varied modes of origin and distribution of offshoots leads
to the conclusion that they may be formed on all parts of the plant, that the form
of the offshoot is constant for each species, or, in other words, that the form of the
individual parts of the offshoot in succeeding generations is repeated as exactly as
the flowers and fruit, but that one and the same species may frequently form two
or even three kinds of offshoots. The Fungus Claviceps purpurea develops
spores which are distributed by honey-sucking insects, also the sclerotia known as
“ergot”, which are scattered from the dry spikes by the swaying movement of the
stem, and thirdly, filamentous spores, which are extruded from asci, and distributed
by wind. The Liverwort Blasia pusilla, develops thallidia in special flask-
shaped receptacles on the surface of the thallus, and spores in the sporogonia. The
form of the offshoot is always adapted to the season and to the distributive agents
available where they are formed. In one case it is more suitable that the offshoots
should be distributed slowly, and step by step, in another quickly and by bounds.
In the spring it may be more advantageous if they are distributed by wind, by
animals in the summer, and by self-scattering mechanisms in the autumn. Steppe-
plants must develop different offshoots from those formed by plants living on the
damp, shady floor of the forest. It is just as obvious that offshoots, which creep
along, above, or under the ground without leaving the soil, must be equipped quite
differently from those which are detached from their place of origin, and either roll
along or are carried by wind, or have to travel long distances as the appendages
of wandering animals. In the former, it is all-important that they should be able
to overcome possible obstacles in the soil; in the latter, that they should not perish
during their journey for lack of food and water. When separated from the soil
they are greatly exposed to the danger of drying up, and even when they have
settled somewhere, the supply of water they require for the formation of organs of
attachment and absorption is by no means assured. Settlers of this kind must
either be so.organized that they can sustain a long-continued drought without
injury, like the offshoots of the Mosses and the soredia of Lichens, or they must
themselves bring with them the necessary water supply, and care must be taken

THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS. 833

that this supply is not lost prematurely by evaporation. As a matter of fact, such
detached offshoots, eg. those of Sempervivum, Sedum, Kleinia, or Mamillaria,
are not only provided with a special aqueous tissue, but also with a cuticle which
is very effective in preventing excessive transpiration. All offshoots, when liberated
from their place of origin, are also provided with the necessary reserves, i.e. con-
structive materials, so that immediately after settling, they can send out absorbent
roots and green leaves of their own initiative, obtain a firm footing in their new
locality, and extract nourishment from it. When the offshoots are distributed by
water-currents, they require neither an aqueous tissue nor protection against drying
up, and it may be due to this fact that detached offshoots are relatively more fre-
quent in aquatic than in land plants and lithophytes.

THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

On the heights of the Kahlenberg, at Vienna, at the edge of the wood, grows
an under-shrub which bears the name of Dorycniwm herbaceum. It is one of the
Papilionacess, and develops spherical one-seeded fruits, which ripen in October.
I once collected from this plant several twigs laden with fruit, for the purpose of a
comparative investigation on which I was engaged, and brought them home and
laid them on my writing-table. Next day as I sat reading near the table, one of
the seeds of the Doryeniwm was suddenly jerked with great violence into my
face. Shortly afterwards I saw a second, third, fourth, and ultimately about fifty
seeds let fly from the small clusters of fruit, and each time I heard a peculiar
sound which accompanied the bursting open of the fruits and ejection of the seeds.
The rays of sunshine from the window had evidently heated and dried the fruits,
and occasioned this surprising phenomenon. The incident reminded me of the
following passage in Goethe’s Travels in Italy:—“I had brought home several
seed-capsules of Acanthus mollis, and put them away in an open box, when one
night I heard a crackling noise, and immediately afterwards a sound like the
impact of small bodies against the walls and ceiling. I could not understand it at
first, but found afterwards that my pods had burst and scattered their seeds all
over the place. The dryness of the room had caused the fruits to ripen in a few
days to the requisite degree of elasticity.”

The fruits of Doryenium and Acanthus may be taken as types of a large
group designated by the name of Sling-fruits. It is found that when these fruits
are ripe, the tissue around the seeds becomes highly tense. The first result of the
tension is that the tissue is rent at particular spots, and this rupture is followed
by a sudden contraction of the segments, which double back and roll up, at the
same time expelling the seeds resting upon them. Sometimes the rolled parts of the
fruits, and, more rarely, the entire fruits themselves, are jerked off simultaneously
with the seeds. There is the greatest variety in this respect, but all the con-
trivances for expelling seeds resemble one another in the fact that through their

agency the seeds reach places beyond the range of the mother-plants.
Vou. IL. 103

834 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

In one class of expulsive fruits the high degree of tension which finally results
in the disruption and rolling up of particular tissues is caused by a swelling up of
the cell-membranes or by the turgidity of the cells. One of the most curious
instances is that of the Squirting Cucumber (Ecballium Elatertwm), which is shown
in fig. 4581, This plant belongs to the Cucurbitacez and its fruit resembles a small
fleshy cucumber beset with bristles and borne by a hooked stalk. The end of the
stalk projects into the interior of the fruit like a stopper. When the seeds are quite

Fig. 458.—Sling-fruits.

‘ Ecballium Elaterium; branch bearing flowers and fruits. 2A fruit detached from its stalk and with its seeds squirting out.
5 Oxalis Acetosella; entire plant with one unripe fruit on a hooked stalk, and ane ripe fruit on an erect stalk ejecting
its seeds; nat. size. 4 Unripe fruit of Oxalis Acetosella; x6. 5 Ripe fruit of Oxalis Acetosella ejecting the seeds; x6.

ripe the tissue surrounding them is transformed into a mucilaginous mass, Also
the tissue in the neighbourhood of the conical stopper just referred to breaks down
at the same time, and thus the connection between the stalk and the fruit is loosened.
In the wall of the fruit there is a layer of cells which is under great tension, and
endeavours to stretch itself out. As long as the fruit is unripe such expansion is
prevented by the tense tissue close to the stalk, but with the ripening of the fruit
this obstacle is removed. The fruit then severs itself from the conical end of the
stalk and at the same moment the expansion of the strained layer of tissue takes
place. The consequence is that the interior of the fruit is subjected to great
pressure, and the seeds, together with the surrounding mucilage, are squirted out

SLING-FRUITS, 835

with considerable force through the hole which was previously closed by the end
of the stalk (see fig. 458 ”),

The Dorsteniacess behave in a manner no less remarkable. As in the case of
Figs so also in these plants, numbers of small flowers are seated upon an enlarged
receptacle, which remains fleshy and succulent after the small one-seeded fruits have
developed from the flowers. The lower portion of each fruit has thick walls, and is
embedded in the receptacle like a hair-follicle in the human skin, whilst the delicate-

Fig. 459.—Sling-fruits.

1 Orobus vernus. 2and % Geranium palustre. + Viola elatior. 5 Card

Tand 8 Acanthus mollis. 9 and 19 Ricinus communis.
coated portion projects above the receptacle in the form of a papilla. When the
seed is quite ripe the turgidity of the outer cellular layer of the thick wall of the
fruit increases, the thin-walled top is torn, the thick walls suddenly close, and the
seed hitherto enveloped by them is violently ejected.

A special case of the expulsion of seeds as from a sling is also found in Oxali-
.dacez, of which the common Wood-sorrel (Oxalis Acetosella, see figs. 458% + °) may
be taken as an example. In this case it is the seed-coat that possesses a special
tumescent tissue adapted to the expulsion of the seeds. One of the deeper layers
of the seed-coat is composed of tense cells and is itself in a highly strained condition,

836 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

whilst the outer layers of cells of the seed-coat are not in a state of tension. When
the seed is quite ripe the cell-membranes in the strained layer of tissue swell up, the
outer layer of the seed-coat, being no longer able to withstand the pressure to which
it is subjected, is rent asunder and the edges of the slit thus formed roll suddenly
back. A violent jerk is given to the inclosed seed, in consequence of which it flies
out through the fissure in the capsule immediately in front of it (fig. 458 5). The
fact of the ejection of the seeds of Balsamacez also has long been known. The
fruit of Impatiens Nolitangere, one of the members of that family, is an oblong
capsule composed of five carpels (see fig. 459°), The walls of this capsule are con-
structed of three layers of cells. The layer lying immediately beneath the epidermis
consists of large and highly turgid cells, and is called the turgescent layer. It is in
a state of great tension, and when the seeds are ripe and the union between the five
carpels gives way along the lines of union, a relaxation of the tension takes place,
the loosened tissue of those lines is torn, the five carpels roll up, and their rapid
movements of involution result in the expulsion of the seeds contained in the fruit.
Cyclanthera eaxplodens and Thladiantha dubia, plants belonging to the Cucur-
bitacesze, as also several Crucifers of the genera Dentaria and Cardamine, in
particular the species shown in fig. 459° (Cardamine impatiens), exhibit similar
phenomena, except that in these cases the carpels do not roll inwards but outwards.

In the instances hitherto dealt with the cause of the expulsion is the turgidity
of cells or the swelling up of cell-membranes with a concomitant maintenance of a
state of extreme tension in a particular layer of tissue situated in the wall of the
fruit. In the next class of cases the phenomenon depends on the desiccation and
consequent contraction of a special layer of the fruit-wall which leads to a rupture
and subsequently to a bending over and rolling up of particular parts of the fruit.
This change is accomplished with great rapidity and has the effect of hurling away
” the seeds or the separate parts of the fruit or even the entire fruit itself. We will
only mention some of the best known instances of this kind.

The fruit of the Marsh Crane’s-bill (Geraniwm palustre; see fig. 4597) has a
5-angled column rising up in the centre of a circle of five carpels. The carpels are
hemispherically inflated at the base, and terminate above in long bristles or beaks.
Each contains a single seed. When the seeds are ripe, the tissue composing the
beaks undergoes desiccation, which, however, is not of uniform intensity throughout.
The outer layer, consisting of several plates of succulent cells, dries up more quickly
than the inner layer, which is composed of thick-walled cells. The result is that the
beak lifts itself away from the axial column, and curls up externally like a watch-
spring. No resistance to this movement is afforded by the delicate dried tissue
which has hitherto served to hold the carpels together, and as the cavity of each
carpel is open along the inner surface, and the seed lies in it simply as though it
were resting in the hollow of a hand, the rapid drawing up of the beak has the effect
of ejecting it in a wide curve away from the carpel (see fig. 459°), In the Marsh
Crane’s-bill, as also in the other large-flowered species of the genus Geranium, the
tops of the beaks continue attached to the axis, and the latter, together with the five

SLING-FRUITS. 837

empty and rolled-up carpels, resembles a chandelier in shape (shown to right of
fig. 459 *),

Those Violets which have aérial stems, such as Viola elatior (see fig. 459 *),
develop capsular fruits, each of which resolves itself into three valves when it bursts
open. The valves are boat-shaped, and the marginal parts which form the sides of
the boats are thin, whilst the keels are very thick and swollen. Inside each boat,
near and parallel to the line of the keel, are two rows of seeds. The valves them-
selves have an exceedingly complex structure. A cross section through one of them
shows a layer of thin-walled parenchymatous cells, a layer of elongated curvilinear
cells, and a layer of broad, greatly thickened cells. The unequal desiccation of these
layers is the cause of the curving up of the lateral walls of the valves, which at last
approach so near to one another as to exercise considerable pressure on the seeds in
the middle. The result of this pressure is that the smooth seeds are shot out with
about the same force as is imparted to a cherry-stone when it is flicked to a distance
by the finger and thumb. The seeds are ejected in regular succession. The foremost
seed of the first carpel goes first, and the seeds at the opposite extremity are dis-
charged last. It is not till the first carpel is quite empty that the second begins to
part with its seeds, and the third only comes into play when the second is finished.
The drawing together of the two sides of the valve always begins at the free
extremity of the valve, and lasts until all the seeds have been ejected.

In many Mimosex, Cesalpines, Papilionacess, Sterculiaces, and Acanthaces
the seeds are expelled by means of a spiral torsion of the valves of the fruit at the
moment that the legume or capsule opens. The wall of the fruit of these plants
includes a soft succulent layer of thin-walled parenchymatous cells, and a hard layer
of strongly-thickened elongated cells, which run obliquely from one edge to the other
in each valve. The rupture of the fruit, and the spiral torsion of its valves at the
moment of their separation, depend upon these diagonal cells of the hard layer,
Each one of these cells winds itself into a spiral as it dries, and consequently the
entire layer undergoes a corresponding torsion. The tissues composed of thin-walled
cells, which are in connection with the hard layer, offer no resistance to the move-
ment, and the rotation is therefore so sudden and violent that the seeds contained in
the pod are projected to a distance. If the fruit is short, the valvular torsion is
confined to 4-1 twists; if long, the spiral includes 2 or even 3 complete coils, and
the valves of the empty fruit are curled up like ringlets (e.g. Lotus corniculatus,
see p. 431, fig. 325%, and Orobus vernus, see fig. 4591). The force of projection
varies according to the thickness of the hard layer. In Castanospermum australe,
where the pod-valves attain to a thickness of 5 millimetres, the sudden torsion causes
the expulsion of spherical seeds, measuring 3°5 centimetres in diameter, and weighing
16 grams. In these cases the valves of the fruit persist upon the fruit-stalks after
the ejection of the seeds, and herein lies the essential difference between them and
those expulsive fruits of which the carpels break away from the stalks with the
seeds. To this class of expulsive fruits belong also several Papilionacez, such as the
Dorycnium mentioned at the beginning of this section, and besides them the genus

838 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

Kitaibelia of the family Malvacee, Alstremeria amongst the Liliacez, several
Acanthacee, including the Acanthus mollis (see figs. 4597 and 459°), which Goethe
has made familiar to us, the wonderful parasite, Lathrea clandestina, and many
Euphorbiacee (e.g. Euphorbia, Hura, Hyenanthe, Mercurialis, Ricinus, see figs.
459° and 459°), In all these plants the fruit-valves are comparatively short, and
the spiral torsion is therefore less clearly manifested. The impulse given to the
seeds by the twisting of the valves is supplemented by various other contrivances
which cannot here be described, and, as a matter of fact, the range of projection in
this group of sling-fruits is wide as compared with that of others.

A peculiar form of sling-fruit is found in several of the Diosmacex, Rutacee,
and Zygophyllacee. In these plants a complete separation of the hard from the
soft layer takes place. When the seeds are ripe the external soft layer dries, splits
along the ventral suture, and contracts strongly. In consequence of this contraction
the hard internal layer, which is in the form of a case inclosing the seeds, is forced
out of the slit. As soon as the hard case is thus set at liberty its two lateral walls
part asunder, assume the shape of the screw of a steamer, and eject the seeds to a
distance. Similar processes occur in the genus Collomia of the family Polemoniacew,
but in this instance it is not the soft outer layer of the valves but the calyx, which,
on drying, exercises pressure on the inclosed case, and the latter, which is extruded,
is not the hard layer only but the entire dry capsule. The liberation of the case is
here materially assisted by the circumstance that the three valves of the capsule
disunite at a time when they are still surrounded by the calyx, and hence exert a
counter-pressure upon the calyx, When once the capsule is freed from the grasp of
the calyx, its valves diverge still more widely from one another and eject their
seeds. In Eschscholtzia also the entire fruit is jerked off the receptacle, but here
the phenomenon depends on the fact that the two valves of the siliquose fruit attain
to a high degree of tension on desiccation and tend to curve outwards. When the
tension has reached a sufficient pitch to sever the connection between the fruit-
valves and the receptacle, the whole fruit is shot away from the stalk in a curve.
In the Stork’s-bill (Hrodiwm, see vol. i. p. 619, figs. 147% and 147+*), and in several
Umbellifers (e.g. Scandia), the entire fruit is not thrown off, but the constituent
parts of the fruit with their tightly inclosed seeds are jerked away from the central
axis,

This cursory survey is sufficient to give an idea of the great variety existing
amongst the sling type of fruit. Of course the fruits in question are always placed
in such a position as to render a free flight of the seeds possible. In every case
where the fruits before ejecting their seeds or being themselves jerked away are
for any reason hidden under foliage-leaves, or are borne by stalks which bend
downwards, as in the Wood-sorrel and the Violet (see figs. 458° and 4584), the
stalks straighten out just before expulsion takes place and lift the fruits up above
the leaves. In most instances the angle of projection is 45°, and, as is well known,
the greatest range of flight is thus attained. The ejected seeds are spherical, oval,
bean-shaped, or lenticular. In the last case they are expelled in such a manner as

SLING-FRUITS. 839

to cut edgewise through the air, and it is the invariable rule for seeds to be so
ejected as to encounter as slight a resistance from the air as possible whatever their
shape may be. Contrivances for determining the direction in which the expelled
body is to move are rare. A first indication of some such adaptation occurs in the
Wood-sorrel (see fig. 458°) and in Ricinus (see fig. 4591), where the seeds are thrust
through an opening of definite shape. In the Acanthaces (Justicia, Acanthus, &.),
the path of projection is determined by the circumstance of the seeds resting before
their expulsion against rigid curved bars springing from the partition-wall which
runs through the fruit (see fig. 459°). The act of expulsion is usually accompanied
by a characteristic noise like that of the bursting of a bladder, and the sound
amounts to a regular detonation in the case of the dehiscence of the fruits of Hura
erepitans. The range of projection is least when the seeds are small and light, and
greatest when they are large and heavy, as is shown by the following table:—

Longest Shortest ‘

Name of Plant. Shape of Seed. ee ee “wet ha projection

Millimetres. | Millimetres.| 728. | in Metres.
Cardamine tmpatiens .......ccccceeeee ellipsoidal 15 0O7 0-005 0-9
Viole CONTIN... iec cece ecceeenneseen ees oval 16 10 0-008 1:0
Doryenium decumbens ......cccccccceere spherical 15 15 0:003 10
Geranium columbinum .....c0ceccceee spherical 2°0 2°0 0:004 15
Geranium palustre ....ce.cceceseeeeeeee cylindrical 30 15 0:005 25
Lupinus digitatus cubical 70 70 0°08 70
Acanthus mollis bean-shaped 14:0 10°0 0-4 9°5
Hura crepitans ...... .. | lenticular 20°0 17-0 0O7 14:0
Barhinic Purpurea ..ccccecccrvecerccnes lenticular 30°0 180 25 150

It will be noticed that as a means of distribution the agency of expulsive fruits
is confined to a very restricted range. As compared with the distances to which
seeds are conveyed by other means, such as the wind, the range of projection
of the most powerful contrivances for expulsion, viz. 15:0 metres, is inappreciably
small. This may account for the facts, firstly, that expulsive fruits are produced
by comparatively few plants; and secondly, that such plants as do possess them are
for the most part denizens of localities that are sheltered from the wind, where,
therefore, the conditions are not favourable to dispersion by that agency. Carda-
mine impatiens, Dentaria, Impatiens, Lathroea clandestina, Mercurialis perennis,
Orobus vernus, Oxalis Acetosella, Viola canina, and V. sylvatica all inhabit retired and
shaded woodlands, whilst others, as, for instance, Geranium palustre and Lathyrus
sylvestris, climb over bushes and hedges on the borders of woods. Mention must
also be made of the fact that in many cases a second mode of dispersing fruits
and seeds acts conjointly with that of expulsion, as is indicated by the name of
Impatiens Nolitangere, i.e. “Touch me not”, Those sling-fruits, for instance,
in which the high degree of tension is due to the swelling up and turgidity of
particular layers of cells, are so constructed that the slightest touch on the outside
causes a relaxation of the tension and the ejection of the seeds in the direction of
the object that has touched the fruit. The animals which frequent the shady woods

840 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

where Impatiens, Cardamine, Dentaria, Oxalis, &c., grow, brush against the fruits
of those plants in the course of their wanderings, and at once receive a charge of
seeds, some of which are sure to be left sticking to the creature’s fur or feathers.
It has long been known that when animals pass over places that are overgrown by
Elateriwm (see fig. 4581) and brush against its fruits, which hang down from
hook-shaped stalks, they are bespattered with the mucilaginous mass in which the
expelled seeds are embedded, and that as soon as they reach a place of rest they
endeavour to get rid of the unpleasant encumbrance.

Several contrivances for the distribution of fruits and seeds remain to be
described which, so far as regards their results, exhibit the greatest resemblance
to the above sling-fruits, although the causes which determine the phenomenon in
their case are utterly different. In the last-named the forcible expulsion is due to
cellular turgescence, or to movements brought about by the drying up of hygro-
scopic cell-layers; in the cases now to be described the result depends solely on the
elasticity of stems and fruit-stalks. The stems and stalks in question are strongly
resilient, and are strained and curved by a force acting from without. The moment
the force ceases to act, their quality of resilience causes them to return to their
former position, and in doing so they jerk the fruits and seeds borne by them to a
distance. Of these contrivances, which are called balistic means of dispersion of
fruits and seeds owing to their analogy to catapults or balistas, we will here deal
with five forms. The simplest occurs in the Composite, whose fruit-capitula are
borne upon erect, comparatively long, elastic, flexible stems. The small fruits of
the capitulum are already detached from their short pedicels by the time they are
ripe and are deposited upon the central disc of the receptacle, which is surrounded
by involueral scales, or at the bottom of the basket-shaped fruit-capitulum into
which the floral-capitulum develops. They are so deeply bedded in this situation
that it is not possible for them to fall out unless subjected to some external impetus.
But the erect resilient stem which bears the capitulum has only to be bent to one
side by a gust of wind or by the touch of an animal for the fruits lying on the
fruit-capitulum (which is flat or excavated as the case may be) to be shot off by the
recoil which ensues. In many of the Composite the involucral scales which form
the enveloping basket bend towards one another at the top so as to constitute a
roof; they are, however, elastic and flexible and very smooth on the inner surface,
so that the fruits when ejected easily slip by them, and yet are to a certain extent
guided in the course they take by the tips of the scales. In other Composites, of
which the genus Telekia is an example, the floral receptacle is thickly clothed with
so-called pales, and the fruits to be ejected, which, it may be noted incidentally, have
no pappus, are embedded amongst these pales. The pales are erect and stiff, and
are edged with small, upturned teeth; the slightest shock sends the fruits a little
higher up amongst the scales, and they cannot then return to their former position,
as the stiff marginal teeth bar the way. The fruits thus seem to make their way
up the scales, step by step, as though they were ladders. If, when they have nearly
reached the top, there comes a gust of wind which sets the peduncles of the capitula

CATAPULT FRUITS, 841

rocking to and fro, the fruits are thrown out from between the elastic tips of the
scales and describe an open curve before they reach the ground, A third group of
Composites, which may be represented by Centawrea Pseudophrygia and C. steno-
lepis, exhibits the following arrangement: The receptacle is destitute of pales, but
the involucral scales form a sort of basket at the bottom of which are the fruits,
In damp weather the tips of the bract-scales close tightly together, and the short
bristles of the pappus crowning each fruit are applied closely to one another. In
warm, dry weather especially, under the influence of a dry wind and sunshine, the
scales part asunder and the basket stands wide open. At the same time the hairs

Fig. 460.—Catapult fruits.

land 2 Salvia verticillata. %,4,5and& Teucrium Euganeum. and 8 Teucrium flavum. % Monarda fistulosa. 10 and
1 Polygonum Virginicum. 1, 3 and 10 nat. size; the others magnified.

of the pappus bristle up, and in so doing raise the fruits to the open mouth of the
basket. If the peduncle supporting the capitulum is now set in motion, the fruits
are tossed out like shuttle-cocks. The bristly pappus-hairs are not in this case
organs of flight; they are short and stiff, and, besides raising the fruits, serve also
to determine the direction of their fall. Balistic apparatus very similar to that
just described is also found in several Iridacew, Liliacew, Caryophyllacee, Primu-
lacece, and Scrophulariacee, only in them the erect, resilient stem does not bear a
fruit-capitulum but a capsule, and the ejected particles are not fruits but seeds.
The seeds are comparatively large and heavy, and are destitute of membranous or
hairy appendages. In all these cases the capsule is situated with its orifice upwards
and only opens in dry weather. As its cavity is very deep, no ejection of the seeds
ensues except when the resilient stalk which carries it sways somewhat violently

to and fro.

842 THE DISPERSION oF SPECIES BY MEANS OF FRUITS AND SEEDS.

The manner in which the fruits of Labiate are thrown off is particularly
remarkable. The fruits in question are spherical, oval, or ellipsoidal nutlets, and
when ripe are still hidden at the bottom of the persistent calyx. The calyx is
either bell-shaped or tubular, and faces laterally; the pedicel supporting it is
resilient, and usually bowed (see figs. 4601%35), If-one presses upon the stiff
points of the calyx with some hard object such as a piece of wood (fig. 460°) the
pedicel is subjected to a strain, and as soon as the pressure ceases it springs back to
its former position, and the nutlets are shot out with great force (fig. 460°). The
path of projection is in this case determined by the two inferior calyx-teeth,
which curve upwards like sledge-runners (see fig. 460°). In many instances, as,
for example, in Teucriwm flavum, T. Euganeum, and Monarda fistulosa (see
figs. 4603456789), there is yet another contrivance for ensuring the proper
direction of flight. This consists in the presence of stiff though pliable convergent
hairs in the calyx-tube, and their function may be compared to that of the grooves
in arifle. Again, in Scutellaria the lobes of the calyx-limb, which is in the form
of a tilting helmet with the visor down, determine the path of the seeds after
expulsion. The result thus artificially attained by bending down the stalks of the
fruiting calyces and letting them fly up again is brought about in nature by gusts
of wind, by drops of rain, and most frequently of all by animals brushing against
the calyces. In the last-mentioned event one or other of the ejected nutlets may
stick to the animal’s coat and be carried to a much greater distance than would
otherwise be the case. This kind of apparatus rarely occurs in plants other than
Labiatw. The nearest analogy is found in the ejection of seeds from the fruits of
several species of the Chickweed genus, eg. Cerastiwm macrocarpum (see p. 448,
fig. 340 *), where the fruits are curved like the letter S, are borne on stiff stalks and
hold the ends that open upwards.

One of the most curious forms of mechanism of the catapult variety occurs in
the North American Polygonum Virginicwm (see figs. 460° and 460"). In this
plant the fruits are on short stalks, and are arranged in spikes on long switch-like
stems. The fruit-stalks are remarkable for the fact that the cells of the cortical
parenchyma, which is greatly developed, have their walls strongly lignified, though
only slightly thickened. It is also noteworthy that between the stalk and the fruit
there is a layer of separation which looks like a joint to the naked eye. The style
is transformed into a decurved beak, which is seated upon the fruit, and terminates
in two little divergent hooks. When one of these fruits is pushed by a passing
animal it is at once detached at the separation-layer and springs away to a distance.
The pressure applied to the fruit is apparently transmitted to the short stalk, and
gives rise to a condition of tension in the tissue of the stalk analogous to that of a
watch-spring. As soon as the pressure ceases the tension relaxes, and the fruit is
cast away with great force. For a long time it remained a mystery how these
fruits were thrown off in the absence of any animals to give the initial impulse.
A few years ago, however, I succeeded in observing the manner in which the long
fruiting switches are swayed backwards and forwards by a boisterous wind,

CREEPING MECHANISMS, 843

and how they brush against one another and against the branches of neighbour-
ing shrubs as they swing, and thus receive the stimulus necessary to cause them
to throw off the fruits. The contact of animals is, however, a more advantageous
means of dispersion, inasmuch as the fruits may be left hanging to their coats by
the hard styles and the range of distribution be greatly increased thereby. When
there is no assistance from animals, and the cast-off fruits simply fall to the ground,
the range of projection is not more than 2-3 metres, which is a comparatively small
distance from the spot where the fruits were ripened,

The limitation of the range of dispersion is still more marked in the case of
fruits which creep or hop along the ground than in those where the action is that
of a sling or of a catapult. The fruits in question have stiff and very hygroscopic
bristles projecting on one side from their external coats, and these bristles continually
change their position according to the varying state of the environment in respect

Fig. 461.—Creeping and hopping fruits.

1 Aigilops ventricosa, 2 Afgilops ovata. 8 Crupina vulgaris. 4 Trifolium stellatum

of moisture, and by so doing propel the fruit or seeds, as the case may be, in a
definite direction. The awns which project from the glumes of Grasses (e.g. Llymus
crinitus, Secale fragile, and various species of Agilops; see figs. 461+ and 461),
the strong bristles in which the bract-scales of the flowers in Restiacee terminate
(eg. the South African plant, Hypodiscus aristatus), the calyx-bristles and stiff
pappus-hairs in Scabiouses and Composites (e.g. Crupina vulgaris, see fig. 461 *), and
the divergent calyx-teeth in Papilionaces (e.g. Trifoliwm stellatum, see fig. 461 *)
constitute structures whereof the different parts alternately approach and recede
from one another and so cause a movement resembling that of creeping. In all
these cases the hygroscopic structures are furnished with small teeth. Sometimes
the teeth are on both sides, sometimes on one side, and sometimes only at the
tip (see figs. 4621%%4), The teeth render retrogression impossible, and to that
extent determine the direction in which the fruit moves. In Avena elatior,
Avena pratensis, and several other Grasses the awns which project from the base
of the enveloping glumes are bent elbow-wise. The part below the bend is
spirally twisted, and as the tissue is extraordinarily hygroscopic, the spiral relaxes
or contracts according to the amount of moisture in the air. This spiral motion
eauses the part of the awn which is above the bend to move like the hand of a
watch, but now to one side, now to the other. Of course this movement can only

844 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

take place provided the part of the awn which undergoes it is not fixed down
anywhere by an obstacle. If one of the lever-arms of the awn encounters a fixed
object on the ground the spiral motion of the lower arm sometimes has the effect
of forcing the tip of the awn over the obstacle, so that the whole structure shoots
obliquely upwards. This phenomenon is especially conspicuous in Avena sterilis,
In this case two glumes furnished with strong bent awns are to be seen on the
fruiting spikelet after it has fallen. An alteration in the environment in respect
of moisture causes the two awns to twist in opposite directions, so as to cross one
another. After pressing one upon the other, they ultimately slip apart with a
sudden jerk, which causes the whole fruit to spring up. This movement is much
more like hopping or jumping than creeping. *

The distance traversed by creeping, hopping, and bounding fruits is seldom
greater than a few decimetres. The movements generally land the fruits almost

Fig. 462.—Fruits which creep or hop along the ground.

1Awn of Aigilops ventricosa. % Awn of Aigilops ovata. 8 Bristles of the pappus of Crupina vulgaris. 4 Calyx-tooth of
Trifolium stellatum; all the figures magnified.

immediately in some cul de sac, where they remain, or else the awns gets entangled
with the above-ground stems and leaves, and in that case the result of the move-
ments is to imbed the seeds, which are concealed in the fruit-scales, in the earth
(see vol. i. p. 617). In such cases no doubt the most important function of the
movements in question is to fix the plants in the soil, but on the other hand it
cannot be denied that a limited form of dispersion may be and is as a fact achieved
by these movements.

The dispersion of fruits through the agency of water takes place in all plants
which undergo fertilization under water and detach their fruits when they are
quite ripe. To this class of fruits belong the Fungi of the family Saprolegni-
ace, and most of those Cryptogams which are known as Algew. Such facts as
have been ascertained by botanists concerning the distribution of the fruits of these
plants in the water have been recorded in previous pages (see pp. 49 and 64). This
method of dispersion is of less importance in the case of Phanerogams, which are
fertilized and ripen their fruits in the medium of the air. At first sight one might

1The hopping movements of the fruits of the Mexican plant named Sebastiana Pavoniana, and of those of
Tamarix Gallica, which belongs to the Mediterranean floral area, are not due to alterations in the tension of
particular parts of the fruit-coat, but are caused by insect-larvee which live inside the fruits. In the case of the
“Mexican Jumping Bean”, the larvae are those of the small lepidopterous insect named Carpocapsa saltitans, and
in Tamaria Gallica those of the beetle Nanodes Tamarisci. *

DISPERSAL BY WATER. 845

suppose that rain-water running off the plants and then trickling along the ground
would be a very effectual means of dispersing fruits and seeds, but closer observa-
tion convinces one that distribution is comparatively seldom effected in this manner,
and that wherever such dispersion does occur it is invariably supplemented by
some other means of dissemination. The best-known instances are afforded by two
plants which, on account of their extraordinary properties, were brought to Europe
from the East by pilgrims and crusaders in the Middle Ages. They were called
“Roses of Jericho”, and all sorts of marvellous tales were told concerning them. One
of these plants is Anastatica Hierochuntica, a Crucifer which grows on the Steppe-
lands of Egypt, Arabia, and Syria, and which has the peculiarity that its branches

Fig. 463.—Fruits which open upon being wetted with water.

1 Anastatica Hierochuntica, dry. 2% The same when wetted. 3 Fruit of Mesembryanth Candolli dry. +The same
when wetted. 5 Fruit of Mesembryanthemum annuum, dry. The same after being wetted.

curve inwards when the fruits are ripe in such a manner as to form a trellis round
the closed, pear-shaped siliquas, which are very numerous and are situated at the
extremities of the ramifications, and to protect them from being touched (see fig.
463"). The shape of the structure in this condition is something like that of an
unopened rose, and it remains unaltered so long as it keeps dry. When moistened
the branches at once open back and stretch straight out (see fig. 463°). The fruits
also open at the same time, and the seeds are then liable to be washed out of the
fruit-valves by falling rain. When growing wild Anastatica remains closed during
the long drought which follows the maturation of the fruits, and it is not till the
winter rains set in that the tangle of branches opens and the seeds are washed out
of the fruits. The second “Rose of Jericho”, Asteriscus pygmeus, is a small plant
of the Composite family, and ranges from the northern portion of the Sahara to
Palestine, being met with in especial abundance in the neighbourhood of Jericho.
In this case the branches do not close together when the fruits arrive at maturity,
but the involueral leaves, which are arranged in a rosette, close up over the capitula

846 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

of fruit and do not open until the winter rains set in and cause the “rose” to
unfold, whereupon the fruits are washed away.

Similar phenomena in connection with the rainfall are exhibited by the fruits
and seeds of the so-called Ice-plants (Mesembryanthemum) which occur in a great
variety of forms at the Cape. The capsular fruits of these plants remain closed in
dry weather; but the moment they are moistened the valves covering the ventral
sutures of the fruit-loculi open back, dehiscence takes place along the ventral
sutures, and the seeds, hitherto retained in a double shroud, are washed out of the
loculi by the rain (see figs. 4633456), Amongst plants belonging to the flora of
Europe, the Yellow Stone-crop (Sedwm acre) responds to the influence of rain in a
manner which reminds one strongly of the Ice-plants above referred to. The carpels
are arranged radially, and are furnished at the base with wing-like borders, whilst
the central part of the external surface of the fruit is in the form of a shallow basin,
In dry weather the five fruit-loculi are closed; but the moment a drop of rain falls
upon the concave centre they open wide, and the next few drops wash out the
seeds, which are of smali size, and convey them to the ground, As the rain trickles
into the tiniest crevices in rocks and walls, the seeds are carried into holes in
vertical or even overhanging cliffs where it would be scarcely possible for them to
be deposited by any other means of dispersion. In the case of Veronica Cymba-
laria, which grows on walls in the south of Europe, the fruits likewise remain
closed so long as the weather is dry and only open when they are thoroughly
soaked. The seeds are then carried, like those of the Stone-crop, into the holes
and crevices of vertical walls by means of the infiltration of rain. Similarly in the
cases of Veronica agrestis and Veronica serpyllifolia, species of Speedwell which
grow profusely on cultivated ground, the seeds are washed out of the gaping
capsules by rain and conveyed to spots where they find conditions favourable to
germination. It is worthy of note that the capsules of Veronica Anagallis, V.
Beccabunga, and V. scutellata, species which grow on banks and in running water,
also do not open until they are thoroughly wetted by rain. The explanation of
this curious fact must be as follows. If the wind were to act as the means of
dispersion there would be a risk of the seeds being deposited on dry places where
they would be doomed to perish. On the other hand, the rain carries the seeds on
to the wet soil of the marsh or into the shallow water of the brook or pond, as the
case may be, where the plant in question finds favourable conditions,

I must again repeat that actual contrivances with a view to seeds being washed
out of open fruits by rain are comparatively rare. This, of course, does not exclude
the possibility of fruits or seeds unprovided with such contrivances being dispersed
by rain, or by the little tributaries of rivulets, which result from showers of rain if
once they are transferred by any means into the channels in question. The rills of’
water which run swiftly down to join larger streams after a violent fall of rain
collect not only sand and earth, but also any seeds that may have been deposited on
the ground by the wind, and they subsequently set them down with the mud at the
edge of the stream. Those fruits and seeds also which fall by chance into running

DISPERSAL BY WATER. 847

water, during transportation by aérial currents, may be floated along, and finally
deposited by the stream. Numbers of fruits and seeds of the most various kinds of
plants are invariably found to have been deposited on the banks of sand by the
sides of mountain-torrents, and on the margins of rivers and rivulets after the water
has subsided from a state of flood. Many of them, it is true, have no chance of
developing, but perish, either because the conditions are unfavourable, or because
they have lost their capacity for germination in the transit; others do, however,
germinate, and some even thrive luxuriantly. But such seeds can only be said to
have been accidentally dispersed by running water, and must not be considered as
instances of adaptation to that method of dispersal.

The same statement applies generally to the chance deposition of the fruits or
seeds of land-plants in the sea. They may be carried away to a great distance by
ocean-currents, may float about for months, and finally be stranded on some remote
coast. Experiments have frequently been made with a view to ascertain which
fruits and seeds retain their power of germination notwithstanding prolonged
immersion in salt water. As a result of these experiments it has been established
that the seeds of Asparagus officinalis, Hibiscus speciosus, and several other plants
do not lose their capacity for germination after immersion in sea-water for a period
exceeding a year in duration, a fact which is in itself of great interest. But such
results are without significance in relation to the dispersion of fruits and seeds,
unless it be also ascertained that the fruits and seeds in question keep afloat upon
the surface of the water. For most fruits and seeds sink at once, and sooner or
later undergo decomposition at the bottom of the sea. The number of fruits or
seeds capable of keeping afloat on the surface for any length of time is extremely
small. Of the fruits which are found floating on the sea we may mention first the
hard-coated fruits of the group of Palms named Lepidocaryne. They have a
smooth, scaly, completely closed envelope which is impermeable to water, and looks
very like a coat-of-mail, and, owing to the fact that this envelope is not in im-
mediate contact with the fruit, but is separated from it by a layer of air, the fruits
are able to float on the surface of the water. The large fruit of the Cocoa-nut
.. Palm also is rendered buoyant by a substantial layer of fibres, which incloses a
quantity of air, and is itself coated by a layer with fatty contents which prevents
the infiltration of water. If fruits of this kind fall into the sea and are cast up by
the waves, the seedlings inclosed in them may develop and become denizens of the
shores to which they have drifted, provided the conditions, in respect of climate and
soil, are such as to permit it. As a matter of fact, fruits cast up by the sea on to
remote islands in the Tropics have been known to develop without any human
interference.

The phenomena connected with the dispersion of fruits and seeds in still water
are altogether peculiar. Currents arising from the slope of the ground do not occur
in such water, whilst currents set in motion by the varying temperatures of different
layers of water, for the most part, ascend and descend merely, and can occasion very
little horizontal displacement of fruits and seeds. The wind is the only agency in

848 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

these circumstances that can supply the propelling force necessary to drive such
fruits and seeds as can keep afloat from one shore to another. Special mention
must be made of three groups of fruits and seeds belonging to this category. These
are, firstly, dry fruits which are rendered buoyant by air-inclosing envelopes, as, for
instance, in the case of the marsh-plants known as Sedges (Carex ampullacea,
C. vesicaria, &e.), where the fruit is surrounded by an inflated utricle; secondly, the
fruits of Water-Plantains, Flowering-rushes, &. (Alisma, Butomus, Sagittaria,
Sparganium, &e.), which are furnished with a thick air-filled cortical parenchyma;
and, thirdly, the seeds of some Water-lilies. In the case of the white Water-lilies

464.—Dispersion of fruits and seeds by the wind.

1 Anthyllis Vulneraria; two fruiting calyces are falling from the plant. 2 Longitudinal section through a fruiting calyx
belonging to the same plant; the pod is visible in the interior. % Trifolium tomentosum; one head of inflated fruiting
calyces is detached, and another is still attached to the stalk. 4 Longitudinal section through a fruiting calyx belonging
to the same. 5 Medicago scutellata. § Ostrya carpinifolia; branch with two fruit-spikes. 7 Longitudinal section through
the saccate cupule which envelops the nut in this plant

(Nympheea), each seed is enveloped in a coat (arillus), which loosely clothes the
outer integument (testa) of the seed, so as to leave a layer of air between the two.
In the species of the genus Nuphar there is no arillus, but the carpels separate
when the fruit is ripe into two layers, of which the outer one is green and succulent,
whilst the inner one is white and charged with air, and incloses a large number of
seeds. In all these cases the seeds are enabled to float by their envelopes, and are
driven along on the surface of the water by the wind.

In a similar manner the wind causes certain detached as well as aggregated fruits
to roll along upon level ground. This phenomenon is observed particularly in regions
where a long period of drought follows the short summer season of development;
and accordingly the plants concerned are especially abundant in the vicinity of the
Mediterranean Sea and in Steppe-lands. Several Umbellifers indigenous to the high

DISPERSAL BY WIND. 849

Steppes of the East produce smooth, ellipsoidal fruits about the size of a hazel-nut
and so light that if one of them is laid on a person’s open hand when his eyes are
shut he does not perceive its presence. The extraordinarily small weight of these
fruits is due to the fact that their structure includes a layer resembling the pith of
the Elder. A fruit of Cachrys alpina measures 13 mm. in length and 10 mm. in
thickness and weighs 0:07 grm.; another Cachrys fruit from Shiraz is 15 mm. long
and 10 mm. thick and weighs only 0:06 grm. When fruits of this kind fall they
are rolled along over the Steppe by the wind and only come to rest when they are
caught in some crack in the parched clay soil or get lodged in a hole ina rock. A
few Papilionacee also produce rolling fruits of the kind. One of the groups of
species belonging to the Medick genus, of which Medicago scutellata (see fig. 464°)
may be taken as a type, has pods which are spirally curled into round balls and
which, when their seeds are ripe, detach themselves from their stalks and are rolled

Fig. 465.—Dispersion of fruits and seeds by the wind. Plantago Cretica,

a little way along the ground every time there comes a gust of wind. The same
thing happens in the case of Blwmenbachia Hieronymi, a native of South America,
belonging to the family Loasacea. Although the spherical fruit of this plant has
a diameter of 2°5 em. it only weighs 0°34 grm. when thoroughly dried. As soon as
the seeds are ripe the fruit-stalk withers and the round fruits, which are then left
lying loose upon the ground, are rolled away by the gentlest breeze. If their career
is stopped anywhere, and they get wetted by rain, the openings which are already
formed in them become enlarged and a quantity of wrinkled seeds fall out.
Paronychia Kapella (see fig. 468°), a plant of wide distribution in the floral area of
the Black Sea, where it grows on dry rocky soil, brings small fruits to maturity in
the height of summer, each of which is surrounded by silvery white membranous
bracts. When the season for the dispersion of these fruits arrives the entire tuft of
fruits, which is in the form of a spherical glomerule, becomes detached from the
branch on which it grows and lies lightly on the ground, where the least puff of
wind imparts to it a swift rolling motion. Sometimes if the ground is uneven the
rolling is converted into a hopping and springing motion, and occasionally such
masses of fruit are raised by powerful gusts of wind and carried considerable
distances through the air. In several species of Clover, such as Trifoliwm globosum,

T. subterraneum, and T. nidifiowm (see fig. 468") there are only a few perfectly
Vou. I. 104

850 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

developed flowers in the cluster growing at the end of the flower-stalk, whilst a
number of abortive flowers are crowded together in a tuft in the middle of the
inflorescence. At the season when the legumes are formed from the fertile flowers
the calyx-teeth of the abortive flowers increase in size and assume the shape of long
hairy bristles, which bend over outwards and form a loose globular inclosure round
the head of leguminous fruits. These balls afterwards become detached from the
stalk and are rolled away by the wind.

Even entire plants are in some cases uprooted or have their stems severed from
the roots at the base in the fruiting season, and are then rolled along like balls by
the wind. The most remarkable instance is that of Plantago Cretica, which is
shown in fig. 465. This is an annual plant possessing an abbreviated main axis from
which springs a tuft of stiff, erect flowering stems. When the fruits begin to ripen
the stems curve down in coils to the periphery of the plant, and by so doing give a
strong pull to the abbreviated axis and to the simple tap-root, which is inserted in
the earth in a vertical position. The soil on which Plantago Cretica grows bemg
completely dried up in summer is full of cracks, and the pull imparted in the
manner described is in consequence sufficient to uproot the plant. The plants
now in the fruiting stage have the form of flattened balls and are very light, so
that the entire structure is rolled along by gusts of wind. Plantago Cretica is also
a type of the so-called “Steppe-witches” and “‘ wind-witches”, which are a source
of so much wonder to travellers in the regions of Steppes. On the high table-land
of Persia there is a plant named Gundelia Tournefortii which grows in loose, round,
prickly sods, and has a tap-root deeply sunk in the earth. When the fruits are ripe
the neck of the root rots away and the round sod then rests simply with its stiff
lower branches in contact with the ground. Whenever the slightest wind begins to
blow innumerable quantities of these sods are set in motion, and are thus dispersed
over the plateau. The herbaceous plants of the Steppes of Southern Russia which
exhibit the phenomenon of a decay of the bases of the stems in the fruiting season
and a consequent liberation of the dry aérial portion of the plant belong to families
of the most various kinds. The most common are Alhagi camelorwm, Centawrea
diffusa, Phlomis herba-venti, Rapistrum perenne, and Salsola Kali. It often
happens that a number of these dry, branching herbs get hooked and entangled
together as they roll along, until at length they form a ball as big as a cartload of
hay. Such balls have also been seen lifted up by whirlwinds and driven bounding
over the plain. It is not surprising that this marvellous phenomenon has appealed
to the imagination of the inhabitants of the Steppes, and has even become a subject
for witch-lore whence have arisen the names Wind-witch and Steppe-witch.

It only happens in a small proportion of these cases of rolling fruits, wind-
witches, and the like, that the seeds are strewn out as they are bowled along; when
this does occur it is usually occasioned by some unevenness in the ground which
gives a sudden jog to the rolling body. In the majority of cases the seeds do not
escape until the fruits are brought to rest by encountering some insurmountable
obstacle, the reason being that the seed-vessels only open when they become wet.

DISPERSAL BY WIND. 851

This brings us back to the fruits of Mesembryanthemum and Anastatica, which were
described on pp. 845, 846. Sometimes these also play the part of rolling fruits.
The capsules of Mesembrianthemum detach themselves from their stalks, the plants
of Anastatica become partially uprooted, and lie during the dry season of the year
loose upon the earth. A puff of wind blows them into hollows in the ground or
cracks in rocks, where they are held prisoners. The seed-cases, however, still
remain closed. At last the winter rains set in, whereupon the capsules open, the
seeds are washed out, and after a short time they germinate on the saturated
ground, to which the rain has conveyed them.

Innumerable are the cases of wind-dispersed fruits and seeds which remain
floating in the air for a period of more or less duration after severance from the
mother-plant, and which have their fall retarded by special contrivances for the
purpose. The conformation of fruits and seeds of this category must be such that
the air offers great resistance to their fall, and it is important that they should
possess as small a weight as possible in relation to their size. It is well known that
the spores of Fungi often remain for a long time floating in the air as constituent
particles of the dust. Some seeds, too, are so extraordinarily light that they also
look simply like dust and are able to remain for a comparatively long period sus-
pended in the air. Amongst such dust-like seeds those of Orchids must be men-
tioned first. A single seed of Goodyera repens, for instance, weighs only 0:000002
grm. Several other plants, particularly parasites and saprophytes which live in
deep beds of humus, possess extremely light seeds, as is shown by the annexed
table :—

| ; Weight of Weight of
Name of Plant. _ Seed Name of Plant. _ Seed

in grams. In grams.

Stanhopea oculata........ccceeee 0000003 | Sempervivum acuminatum......... | 0°00002

Monotropa glabra.......cccccccceees 0:000003 | Parnassia palustris.......cccccceees 0°00003

Pyrola unsflor a... cicceccccvsenceves 0000004 | Sedum maximum......... iisaneanwes 000004

MBUU1CUS CTECEUS ...eeee ccc ceceneeees 0000006 | Lepigonum marginatum .......+. 000007

Gymnadenta cOnopsed............+++ 0000008 | Sprrea ArUncus .......ceseereeeeenes 0:00008
Orobanche 1onanthd.......s.ccereees 0-00001 eromicd Cphylla..cr.ccreeccereeeee 0°0001

To enable these seeds to float in the air for as long a time as possible they are
more or less flattened, and their centre of gravity is so placed that they always
present the broad side to the direction of descent. The same form of adaptation
occurs in seeds which are shaped like leaflets, scales, or delicate discs. A compressed
seed is usually surrounded by an attenuated margin, a membranous border, or a
radiating fringe of extremely fine processes, as Mm Funkia, Lilium, Tulipa, Fritil-
laria, Rhinanthus, Veronica, Lepigonum, Cinchona, Bignonia, Dioscorea, and
Heliosperma (see p. 423, figs. 318“ *7, and figs. 466*+5). In some cases the entire
pericarp is modified in this manner, as in Hymenocarpus, Mattia, Peltaria, Ptelea,
and Ulmus (see fig. 4674, and p. 148, fig. 282°). Amongst Umbelliferee, Mimosen,
Papilionacez, and Crucifere cases also occur in which the mericarps, the segments
of siliculas and lomenta, or the seed-studded valves of ordinary pods and siliquas,

852 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

according to the particular plant considered, are in the form of scales and leaflets
which become detached separately. Instances of this kind are afforded by Artedia

squamata, Megacarpea laciniata, Mimosa hispidula, Aschynomene glabrata, and
Lunaria rediviva (see figs. 467 + 5", and p. 445, fig. 3391, and fig. 466 *).

With these forms may be classed also such fruits and seeds as are furnished
with wing-shaped appendages. The wings are either produced from the seed-coat,
as in Pines and Firs (see p. 441, fig. 3355), or else arise from the carpels. A single
wing, which stands out to one side, is developed in the case of the pods of some
tropical Leguminosae (e.g. Securida virgata and Centrolobiwm robustum; see p. 445,
fig. 339°), and in the separate parts of the double fruit of the Maple and of the

Fig. 466.—Dispersion of fruits and seeds by the wind.

1 Siliquose fruit of Lunaria rediviva; the two valves of the fruit have become detached; seeds are fastened to the inside
of each valve. 2 Opened capsule of a Bignonia from which winged seeds are being carried off by the wind. 8 Capsule
of Heliosperma quadrifidum after dehiscence; the seeds are being shaken out by the wind. 4A seed of Heliosperma
quadrifidum magnified. 5 Capsule of a Di ‘ea after dehi , the winged seeds being blown away by the wind.

Banisterias, belonging to the Malpighiacee (eg. Acer Monspessulanum: and
Bamisteria Sinemariensis; see figs. 4677 and 467%), The achenes of Birches
and of the Tree of Heaven (e.g. Betula verrucosa and Ailanthus glandulosa; see
figs. 467? and 467”) bear two laterally placed wings in each case. The mericarps
of many Umbellifere (e.g. Opoponax Cretica and Laserpitium latifoliwm; see
figs. 467° and 467") have wings projecting from the back; the fruits of some
Polygonums (eg. Polygonum dumetorum and P. Sieboldi; see fig. 467°) are
furnished with three wings, and those of Triopteris bifwrca, one of the Mal-
pighiaces, with four wings, of which two are large and two small (fig. 467%). In
other cases some of the floral-leaves are transformed into wings for the fruit,
as, for instance, in Dryobalanops, of the family Dipterocarpes, in which five sepals
are in the form of long wings (see fig. 4685), and in Gyrocarpus, of the family
Combretacex, in which two of the 4-7 unequal segments of the calyx are similarly
adapted (see fig. 467°). It is of common occurrence for the fruits to become,winged

DISPERSAL BY WIND. 853

in consequence of the continuous growth after the flower has faded and the ultimate
desiccation of persistent bracts, as is seen in the Hop (Humulus Lupulus), the

Fig. 467.—Dispersion of fruits and seeds by the wind.

8 Polygonum Sieboldi. + Ptelea trifoliata. »% Alschynomene glabrata.

1 Megacarpea laciniata. 2 Ailanthus glandulosa.
Triopteris bifurca. 10 Acer Monspessulanum.

6 Opoponas Cretica. 7 Banisteria Sinemariensis. § Gyrocarpus Asiaticus. °
ll Artedia squamata. 12 Betula verrucosa. 18 Laserpitium latifolium.

Lime (Tilia intermedia) (see

Oriental Hornbeam (Carpinus Orientalis), and the
in the Tree of Heaven (Adan-

figs. 4681 and 4687). In many cases, as, for instance,

854 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

thus), the two wings exhibit a slight spiral twist resembling a propeller; this
occasions a peculiar gyratory motion of the fruit as it sails along in the air.
Wherever there is only a single wing which projects from one side, the centre of
gravity has an eccentric position, and the fruits and seeds of this class spin quickly

Fig. 468.—Dispersion of fruits and seeds by the wind.

1 Carpinus Orientalis, 2 Tilia intermedia. 8 Armeria alpina. 4 Melica altissi 5 Dryobalanops. §& Par
7 Briza maxima. 8 Scabiosa graminifolia. 9 Humulus Lupulus. 10 Trifolium nidiyicwm.

as they fall freely through the air. The motion in question is particularly well
marked in the half-fruits of the Sycamore and the seeds of Pines.

The same object as is attained in the above cases by the development of alate
processes is brought about in other plants by the transformation of dry bracts or
floral-leaves into light, loose, saccate, or inflated envelopes round the fruits or seeds.

DISPERSAL BY WIND. 855

When quite dry, these envelopes are extremely thin and delicate, and sometimes
their weight is still further reduced by a portion of the tissue being torn during
desiccation, in which case the whole assumes a sieve-like or latticed appearance.
The small fruit within the envelope defines the position of the centre of gravity,
and consequently determines also the attitude of the structure as a whole that best
adapts it to dispersion by the wind. In several Papilionacee, as in Callipeltis
cucullata and the yellow-flowered species of Clover (eg. Trifolium agrarium
and T. badiwm; see figs. 4691,%% 45), the dried petals of the corolla are fashioned
into an envelope which incloses the small 1-seeded legume, and in several species.
of Lady’s Fingers (e.g. Anthyllis tetraphylla and A. Vulneraria; see figs. 4641

Fig. 469.—Dispersion of fruits and seeds by the wind.

Trifolium badii —1 Inflor 2 Same with fruit ripened. 3 Flower. +4 Fruit enveloped in the dried petais.
5 Longitudinal section through the fruit in its envelope of petals.—Verticordia oculata. 6 Fruit. 7 Longitudinal section
through the fruit. 8 Five “feathers” from the fruit, 3%, 4, 5, and 8 magnified.

and 4647), and some species of Clover of the tribe Vesicastrum (eg. Trifolium
fragiferum and T. tomentosum; see figs. 464° and 4644), the inflated calyx plays
the same part. In many Labiates also (e.g. Calaminta, Salvia, Thymus), the calyx
is converted into a dry, saccate envelope, which is severed from its stalk by any
external stimulus, and then serves as a means of dispersing the ripe nutlets con-
tained in it. In the Hop-hornbeam (Ostrya, see figs. 464° and 464"), the small nut
is enveloped in the sac-like bract; and in many Grasses, as, for instance, Briza
maxima and Melica altissima (see figs. 4684 and 4687), the dry glumes constitute
a covering to the small fruit which adapts it to dispersion by the wind.

One of the commonest devices for keeping fruits and seeds suspended in the air
is of the nature of a parachute. This form of mechanism occurs in the shape either
of tufts of hairs or of membranous borders. In Willow-herbs (Epilobiwm; see
fig. 472°), Asclepiadaceee (e.g. Cynanchum, see fig. 471°), and several Bromeliacess

856 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

(eg. Tillandsia; see fig. 475*) only one pole of the seed is furnished with a tuft of
hairs, whilst in Adeniwm (see fig. 471°), belonging to the family Apocynaceze, both
poles are so provided. In Valerianaces (eg. Valeriana; see fig. 471°) and in
Composites (e.g. Senecio and Taramacwm; see figs. 4711%°) the tuft of hairs which
acts as a parachute springs from the upper extremity of the achene. Sometimes
the parachute and the body it keeps in suspension are connected by a slender stalk
(eg. in Tillandsia and Taraxacum); but usually the former is directly sessile on
one extremity of the seed or indehiscent fruit as the case may be. In Verticordia
(see figs. 469%".8), of the family Myrtacew, a strange and beautiful parachute is
formed by five petals which are in the form of little fans, each composed of ten

Fig. 470,—Dispersion of fruits and seeds by the wind.

Rom)

2A me sylvestris. % Gossypium Barbadense.

feather-like lobes, and in some Labiate, as, for instance, Micromeria nervosa (see
fig. 4717), the radiating, hair-studded segments of the fruiting calyx constitute a
similar apparatus. On the other hand, in several other Labiate (eg. Ballota
acetabulosa), in many Plumbaginaces (e.g. Armeria; see fig. 4685), and in several
Dipsacez (e.g. Scabiosa; see fig. 468°) the parachute is developed from the delicate,
dry membranous calyx or from the epicalyx. Nor must reference to the Cape
Silver Tree (Leucadendron argentewm, one of the Proteaces) be omitted. The
fruits here are produced in large cones not unlike those of the Stone Pine (Pinus
Pimea) in form and dimensions. Each bract of the ripe cone subtends a fruit
consisting of a nut with persistent wiry style and stigma. The 4-lobed perianth
also persists as a membranous parachute, its originally free apices having become
connate above the nut and around the style. Ultimately the original attachment of
the perianth below the ovary becomes dissolved, and as the nut falls out of the cone

DISPERSAL BY WIND. 857

the style (with nut suspended below) slides out of the hole, around which the
perianth-lobes are connate, until its further progress is arrested by the button-like

Fig. 471.—Dispersion of fruits and seeds by the wind,

1 Senecio vulgaris. 2 Adenium Honghel, % Valeriana tripteris, * Typha Schuttleworthii. 5 Eriophorum angustifolium.
6 Cynanchum fuscatum. 7 Micromeria nervosa. §% and » Tarawacum officinale. 10 Salia Myrsinites,

stigma. The perianth here forms a beautiful parachute, with the nut hanging
freely below at the end of a string, like an enterprising balloon-gymnast.

From the fruits and seeds equipped with parachutes we pass to those which are
embedded in masses of wool or in envelopes of silky hairs, and are thereby enabled

858 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

to remain poised in the air. The hairs arise either from the surface of the seed-coat
(testa), as in the Cotton trees (Bomba and Gossypiwm; see figs. 4701 and 470%), or
else they spring from the base of the seed, as in Poplars and Willows (Populus
and Salix; see p. 423, figs. 318% and 3184; p. 424, fig. 319 and fig. 4717). In the
Bulrush (Typha; see fig. 471*) they take their rise from the pedicels of the fruits,
and in several Ranunculaceew (eg. Anemone sylvestris; see fig. 470°) from the
achenes themselves. In other cases they arise from the floral-leaves, as, for instance,
in the Cotton-grass (Eriophorum, see fig. 471°), where the structure which repre-

Fig. 472.—Dispersion of fruits and seeds by the wind.

1 Melica Balanse. 2 Calamagrostis Epigeios; nat. size. 3The same magnified. 4 Geum
speciosus, § Epilobium collinum. 7 Clematis Flammula. .

sents the perianth is transformed into delicate hairs, and in Trifolium plumosum,
where the fruiting calyx is wrapped in wool. In many Grasses the glumes are
beset with extremely fine hairs (e.g. Melica and Calamagrostis; see figs. 4721? 8),
in Micropus, of the Composite, long hairs project from the scales of the involucre
and envelop the entire capitulum in a flocculent mass, and in the Venetian Sumach
or Wig-plant (Rhus Cotinus) the stalks of abortive flowers are covered with a
woolly down, which serves for the dispersion of the fruits, whose stalks are usually
free from wool. Lastly, we have the cases where the fruits or seeds are kept
suspended in the air for a more or less prolonged period by means of special hairy
tails. Hither the seeds are tailed at both ends, as in Aschynanthus (see fig. 472°),
one of the Gesneracex, in which the tiny seeds are furnished with two long hairs,
one at each end, or else the style lengthens after the flower has faded and becomes
converted into a spirally-curved tail, which remains attached to one side of the

Set wa Kae<

DISPERSAL BY WIND, 859

achene, and acts like a parachute, as may be seen in Gewm, Atragene, Pulsatilla,
and Clematis (see figs. 4724 and 472 "). In some Grasses, such as Stipa (see vol. i.
p. 619, fig. 1471), an awn is developed in the form of a long feather, which soars
above the tightly-closed glumes inclosing the fruit.

Several of the fruits and seeds above described are directly exposed to the wind.
Owing to the fact that the desiccation of the envelopes and stalks of the fruits at
the time of ripening of the seeds renders certain layers of tissue brittle, a moderate
wind is sufficient to cause the fall of such fruits, and the same gust that brings about
their severance from the plant drives the fruit along
in a horizontal direction. The fruit does not fall to
the ground until the wind drops, or until its pro-
gress is arrested by some obstacle.

Many other fruits and seeds detach themselves
spontaneously from the mother-plant when they are
ripe, but are not directly exposed in consequence to
the full shock of the wind. In these we find many
contrivances for the purpose of ensuring that the
parts to be dispersed shall be brought out from their
shelter, and given over to the wind at the proper
time. In some tropical Orchids which are epiphytic
on the bark of old trees (viz. Aerides, Angreecum,
Sarcanthus, Saccolabium, &c.), the capsular fruits
contain, in addition to the small seeds, hair-like cells,
with spirally-marked and obliquely-pitted walls (see
fig. 473). Vanda teres (see fig. 4751) may be taken
as a type of this group. The hair-like cells in
question are woven together into a sort of felt.

Fig. 473.—Seeds of the Orchid Vanda teres,
which are moved from the interior to the

They are extremely hygroscopic, and twist and surface of the capsule by hygroscopic
‘ < - - hair-like cells, and are thus exposed to
turn about in a curious manner if the slightest the wind; x100.

change of condition in respect of moisture occurs.

When the valves of the capsules move apart under the influence of a dry wind, an
active movement is simultaneously initiated in the matted hairs. The felt becomes to
a certain extent puffed up, and consequently it squeezes out between the valves of the
capsule, and drags the seeds, which are imbedded amongst the hairs, from the interior
to the surface of the capsule, where they are liable to be blown away by the least
breath of wind. This happens, as was said, when a dry wind is blowing. In wet
weather the capsules close up, and conceal both hairs and seed once more in their
interior. Similar phenomena may be observed in the fruit-capitula of some Com-
posites whose fruits are spontaneously detached from the receptacle on ripening.
In damp weather the loose achenes lie hidden in the involucral cup, as though at
the bottom of a basket, and the hairy pappuses appended to the achenes are clubbed
together. When the atmosphere is dry, the involucre, which is composed of hygro-
scopic scales, opens, and the pappuses of the fruits within spring apart, and so act as

860 THE DISPERSION OF SPECIES BY MEANS -OF FRUITS AND SEEDS.

levers. The fruits are speedily raised by this means above the edge of the open
involucre to a sufficient height to expose them to the wind. In some other Com-
posites, such as the Dandelion (Taraxacum), the fruits do not detach themselves
spontaneously from the floral receptable when they are ripe. The segments of the
involucre close together in wet weather, as do likewise the hairs or plumes of the
pappus. In dry weather the involucre opens, whilst the feathers of the pappus
diverge so as to assume the form of a parachute, and in that condition offer a com-
paratively large surface for the wind to act upon. A moderate gust of wind is now
able to lift the fruits, with their expanded parachutes, off the receptacle and carry
them away (see fig. 471°). H no breath of wind stirs, they remain upon the
receptacle; the damp atmosphere of evening causes both parachutes and involucre

Fig. 474.—Dispersion of fruits and seeds by the wind. Fruits of a Thistle (Cirsium nemorale) floating in the air and becoming
detached from their parachutes and dropping to the ground whenever they encounter an obstacle in the course of their
flight.

to close up again, and the process of dispersion is suspended until next day, when
the air is dry once more and the sun shining. In Andropogon Ischemum, Avena
pratensis, and many other Grasses, the flowering glume has an awn composed of
spirally-marked and highly hygroscopic cells, and bent like an elbow, and this awn
undergoes a marked spiral torsion, accompanied by a slight downward flexure
whenever the air is dry. The distal arm of the awn is liable to get pressed against
objects in the course of these movements, and it then acts as a lever in raising the
fruits above the outer glumes. They are then easily blown away by a puff of dry
wind. In several Scabiouses, also, the breaking up of the fruit-capitulum, and the
raising of the fruits with a view to their dispersion by the wind, are occasioned by
. a bristling movement on the part of the hygroscopic sete of the calyx. Each fruit-
let in the Valerian is surmounted by a pappus of delicate feathery hairs, When the
air is damp these feathers are folded together; when it is dry they become unfurled
(see fig. 471°). In this condition of divergence, they present an ample surface to
the wind, and the slightest gust detaches the fruits and blows them away. A similar

phenomenon occurs in Dryas, and in some other plants; but we cannot now enter
into the details of these cases,

DISPERSAL BY WIND. 861

, In the case of Willow-herbs (Zpilobiwm) and of some Pines (Pinus nigricans,
P. sylvestris, &c.) the fruit-valves and fruit-seales which cover the seeds only open
back under the influence of the sun’s warmth, and when a dry wind is blowing,
and the same wind which thus operates on the valves and scales also carries off the
seeds the moment they are exposed, they being furnished with wings or tufts of
hair with a view to aérial dispersion. The reader must be referred to p. 447 for a
description of the manifold effects of a dry wind on the fruits and seeds in question.
First, the dry capsules open; secondly, the seeds, hitherto lying in the interior of
the fruits, where they are protected against moisture, are shaken out by the swaying
to and fro of the elastic fruit-stalks; and thirdly, these seeds are caught up and
scattered by the wind.

The distance to which fruits and seeds which are adapted to aérial transit by
means of wings, hairy tails, parachutes, inflated envelopes or woolly coverings, as the
case may be, are conveyed by the wind depends on the degree of perfection of their
mechanism, on the condition of the air in respect of moisture, and on the strength
of the current of air by which they are transported. When the weather is calm and
sunny, innumerable of the lighter fruits and seeds are carried up to a great height
by the ascending currents which are generated in the atmosphere; but they usually
descend again after sunset at a little distance from the spot where they were taken
up. Such excursions do not conduce so much to a dispersion of plants over large
areas as to their deposition on shelves and in crevices of steep walls of rock, where
seeds would not otherwise easily acquire a footing. Currents moving in a horizontal
direction may, it is true, convey their freight of fruits and seeds over extensive
tracts of country, but very exaggerated notions are usually entertained concerning
the distances thus attained. Amongst the numerous species of fruits and seeds
blown by storms of wind to the tops of the Alps and left upon the snowfields above
the glaciers, not a single one derived from distant parts (.e. from another district)
has been found after careful examination of the deposited matter; and from this
we may infer that, even on mountains, fruits and seeds are scarcely conveyed any
further by a raging wind than when they are blown from one side of a valley to
the other.

In many plants the wings or parachutes, as the case may be, only remain
attached to the seeds or fruits for the period of their journey through the air. If
the winged seed of a Pine gets stranded anywhere the membranous wing drops off,
and the seed is then no longer capable of flight. This phenomenon is even more
marked in the fruits of Thistles (e.g. Cardwus and Cirsium; see fig. 474). The
achenes, which are comparatively large, are supported by parachutes and float
quietly in the air, but the moment one of them strikes against any obstacle the
fruit severs itself from the parachute and falls to the ground. There can be little
doubt that to this mode of dispersion must be attributed the common occurrence of
Thistles at the foot of walls and in hedgerows, inasmuch as the floating fruits are
carried against such structures with especial frequency. In other cases the fruit or
seed maintains permanently a firm connection with the parachute, and the latter

862 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

serves to fasten it to some place where the conditions requisite for germination are
present. For instance, when the seeds of Tullandsia (see 475?) come into contact
with the boughs of old trees, as they are blown along in a horizontal direction, they
fasten on to the bark where they are able to germinate immediately. Thus the
pappus to which the seed owes its buoyancy serves subsequently to anchor it toa
substratum favourable to its development.

The modes of dispersion of fruits and seeds through the agency of animals are

3 I
\ M

)
\

|

Fig. 475.—Dispersion of fruits and seeds by the wind.

1 Capsule of Vanda teres, from which the seeds have been transferred to the air by means of hygroscopic hairs, and are being
blown away. 2 Open capsule of a Tillandsia; the seeds are being lifted out by the wind by means of their parachutes.
If a-seed is blown against the bark of a tree it is anchored there by the hairs of the parachute.

almost as varied as the different methods of dissemination by the wind. In many
cases such dispersion is brought about by the animals using the fruits and seeds in
question for food; the undigested parts are excreted, and any embryos which may
have survived the passage through the alimentary canal subsequently germinate. As
the fact of this mode of dispersion has been a matter of dispute amongst botanists,
and could only be established by experiment, 1 determined to feed various animals
with selected fruits and seeds, and to ascertain first of all whether the embryos
preserve their vitality after passing through an animal’s intestinal canal. Fruits
and seeds belonging to 250 different species of plants were used for the purpose, and

| ; \ ! ij ried
I Na Pins |

DISPERSAL BY ANIMALS, 863

the following birds were fed with them: blackbird, song-thrush, rock-thrush, robin,
jackdaw, raven, nutcracker, siskin, goldfinch, serin-finch, titmouse, bullfinch, cross-
bill, pigeon, fowl, turkey, and duck; and also the following mammals: marmot,
horse, ox, and pig. After each meal the feces were examined, to ascertain what
seeds they contained, and were then laid on a separate bed of earth, and at the same
time fruits and seeds of the same plants which had not been used for food were
planted in an adjoining bed. It would be out of place to set forth here all the
precautions which it was necessary to take in conducting these laborious researches,
and I shall confine myself to a statement of the most important results obtained
from 520 separate experiments.

As regards the mammals subjected to experiment very few words will suffice.
Almost all the fruits and seeds administered to them, whether they took them
voluntarily or unawares mixed with their ordinary food, were destroyed either at
once or upon being chewed with the cud. It is true that a few millet-seeds germin-
ated from the ox-dung, and must therefore have escaped being crushed during
rumination, and that one or two solitary specimens of lentil-seeds and oat-fruits
similarly passed uninjured through a horse, whilst Cornus alba, Hippophae rham-
nordes, Ligustrum vulgare, Malva crispa, Rhaphanus sativus, and Robinia
Pseudacacia all germinated after passing through a pig; but the number of the
seedlings so obtained was scarcely appreciable as compared with the number of
fertile seeds swallowed in the animals’ food, and the fruits and seeds of about 60
other species of plants completely lost all power of germination during their passage
through the intestines. The birds resolve themselves into three groups in relation
to the matter in question. The first group includes those which grind up even the
hardest fruits and seeds in their muscular and hard-coated “ gastric mills” which are
in addition usually filled with small stones and sand. Amongst these, some strip
the fruits and seeds when they first lay hold of them, and thereby condemn them to
destruction. To this group the following birds of those employed in the experi-
ments belong, viz. the turkey, the hen, the pigeon, the cross-bill, the bullfinch, the
goldfinch, the siskin, the serin-finch, the nutcracker, the titmouse, and the duck.
No seed capable of germination was found under ordinary conditions in the excre-
ments of these birds; only when on a few occasions food was forcibly administered
to the hen and to ducks, so that their crops must have been overloaded, were a few
seeds found to have escaped pulverization, and to still possess the power of develop-
ment. The seeds in question belonged to Arenaria serpyllifolia, Papaver Rheas,
Sisymbrium Sophia, Ribes rubrum, Ligustrwm vulgare, Fragaria Indica, and
other species. Ravens and jackdaws form a second group, in that the stones of the
drupes and hard-coated seeds of the berries which they ate passed uninjured through
the intestine, whilst soft-coated seeds and fruits were all destroyed. It is worth
mentioning in particular that after these birds had been fed with cherries their
excrements contained cherry-stones 15 mm. in diamater, every one of which was
able to germinate. Of the birds selected for experiment, the blackbird, the song-
thrush, the rock-thrush, and the robin belonged to a third group. Of these the

864 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

blackbird was the least fastidious about its food. It even swallowed the fruits of
the Yew without afterwards relieving its crop of the stony seeds, and it never
rejected a single fruit that was mixed with its food. The song-thrush refused all
dry fruits of 5 mm. diamater or more, even when they were mixed with the finely-
chopped meat with which the bird was fed. They also avoided certain strong-
smelling fruits, such as that of the Yarrow. On the other hand, the aromatic fruits
of Umbelliferes (e.g. Bupleurum rotundifolium and Carwm Carvi) were eaten with
great avidity. The seeds of the Tobacco-plant, Henbane, and Foxglove mixed with
the food were not rejected and caused no ill effects, and no more did the berries of
the Deadly Nightshade, which were devoured greedily. On the other hand, a song-
thrush sickened after eating berries of Phytolacca. When fleshy fruits with seeds
of diameter exceeding 5 mm., such as those of Berberis, Ligustrwm, Opuntia, and
Viburnum were introduced into the crop, the pulp passed thence into the gizzard,
but all the seeds were thrown up. Many seeds, as, for example, those of Lychnis
flos-Jovis, were carefully removed from the rest of the food with which they had
been mixed. The seeds of fleshy fruits which were greedily devoured were thrown
out of the crop if the stones which they inclosed measured as much as3 mm. The
interval of time between ingestion and evacuation was surprisingly short in the
birds of the third group. A thrush fed with Ribes petreum at 8 o'clock in the
morning excreted numbers of the seeds after the lapse of three quarters of an hour,
and seeds of Sambucus nigra were found to have passed through the alimentary
canal in half an hour. The majority of seeds took from 14 to 3 hours to perform
the journey. Curiously enough, the small smooth fruits of Myosotis sylvatica and
Panicum diffusum were retained for the longest period. Of the fruits and seeds
which passed through the intestine of one or other of these birds, 75 per cent
germinated in the case of the blackbird, 85 per cent in the case of the thrush, 88
per cent in the case of the rock-thrush, and 80 per cent in the case of the robin.
The germination of fruits and seeds that had undergone ingestion and excretion was
usually (.e. in from 74 to 79 per cent of the cases) tardy as compared with that of
similar fruits and seeds which had not been treated in this way but were only germi-
nated for the purpose of comparison. Only in the case of a few berries (e.g. Berberis,
Ribes, Lonicera) was the period of germination hastened. The seeds of such plants
as grow on richly-manured soil (e.g. Amaranthus, Polygonum, Urtica) after passing
uninjured through a bird’s intestine produced stronger seedlings than did those
which were cultivated without such preliminaries.

From these experiments it is evident that the dispersion of edible fruits through
the agency of thrushes and blackbirds is not, as was formerly supposed, an
exceptional phenomenon obtaining in the Mistletoe only, but one that may take
place in the case of many other plants, and other observations prove that, as a
matter of fact, it does take place. Plants possessing fleshy fruits are undoubtedly
often disseminated in this manner. The occurrence of such plants as epiphytes upon
trees, and also their unexpected appearance on the tops of high rocks and old walls
thus receives a natural explanation.

DISPERSAL BY ANIMALS, 865

The phenomenon in question also enables us to interpret the meaning of the
changes undergone by fleshy fruits at the season when their dispersion becomes
desirable, inasmuch as they serve the purpose of attracting animals, and the same
consideration applies to the contrivances whereby animals are discouraged from
taking the fruits before they are ripe. Mention has already been made of these
latter contrivances on p. 444; and as regards the attraction of animals with a view
to the dispersion of ripe fruits the following particulars are of especial interest:
Fruits and seeds that are still unripe are hidden amongst the leaves of the mother-
plant, have a green colour resembling that of the foliage, and are destitute of scent.
On ripening the fruits are exposed, the coats of the fruits acquire a conspicuous
coloration, and frequently emit a strong scent. In the cases where the seeds alone
are dispersed and the pericarps are left behind, as, for instance, in Pwonia Russi,
Euonymus verrucosus and Magnolia grandiflora, the capsules or follicles burst.
open, and the seeds are of a bright red or yellow colour, sometimes flecked with steel-
blue and black, which renders them visible from afar. In the above-named species
of Huonymus and Magnolia they emerge from the pericarps and hang at the ends.
of threads which renders them even more conspicuous. The particular colour assumed
by fruits and seeds at the time of maturity varies according to that of the foliage
by which they are surrounded. The different tones of red stand out best from a
green environment; therefore, for plants with evergreen foliage (eg. Ardisia,
Gaulteria, Ilex, Taxus, Arbutus Unedo, Arctostaphylos uva-ursi, Vacciniwn
Vitis-Idcea) a red coloration is the most advantageous. Also in the case of plants.
with foliage which, although not evergreen, does not acquire an autumnal tint at the
season when the fruits are ripe, e.g. the Strawberry, the Raspberry, the Currant,
the Wild Cherry, and the Red-berried Elder (Sambucus Hbulus) the red hue of the
fruits is of great value. On the other hand, red fruits would stand out but little
against a background of foliage that had already donned the red or yellow tints
of autumn by the time they ripened, and accordingly the fruits of Ampelopsis
hederacea, Cornus sanguinea, Prunus Padus, Arctostaphylos alpina, Vaccinium
Myrtillus and V. uliginoswm, &e., are, as a fact, blue or black. Sometimes the.
fruits are black and the fruit-stalks red, as in Sambucus nigra, or the fruits are only
coloured on the side exposed to view, as in the Apple and the Pear. The fruits of
the Quince and the Pine-apple are set off by their yellow colour from the blue-green
foliage. White berries, such as those of Cornus alba and Symphoricarpus, occur
principally in plants which cast their leaves before the fruit is ripe. Standing out
against the brown or gray background formed by the leafless branches and the
fallen leaves of late autumn these white fruits are clearly visible. The extent to
which fruits are advertised by their scents is a matter of common experience, and
we need only refer for illustration to the Strawberry, the Raspberry, the Quince, and
the Pine-apple.

Seeing that the seeds and stones containing seeds of the fleshy fruits eaten by
thrushes and blackbirds only remain a short time in the crop and intestine of the

bird, it is probable that the plants in question are disseminated by this agency to
Vou. I. 105

866 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

the distance of a few leagues at most, in the course of a single year, and that it
takes many years to distribute them, step by step, as it were, over large areas. We
may reasonably suppose that distribution is effected principally in the direction of
those parts of the world towards which thrushes and blackbirds are in the habit of
journeying by short daily stages when autumn, the season of the maturity of most
fleshy fruits, sets in,

It is well known that nutcrackers, jays, squirrels, and marmots, keep stores of
food in larders, which they fit up in holes in rocks or in the earth or in some other
secret hiding-place of the kind, and that such fruits and seeds as they conceal there
are liable to be left permanently for one reason or another. The hiding-place
may be forgotten, or, as is still more likely, the creature that occupied it may fall
a victim to a bird of prey. The fruits and seeds may then germinate in the place
of concealment, and, inasmuch as the latter is always more or less distant from
the spot whence the fruits were taken, this must also be accounted one of the modes
of dispersion of the plants in question. I have myself observed this curious
phenomenon also in the case of the dissemination of the Arolla Pine (Pinus Cembra)
by nuterackers, of Beeches, Oaks, and Hazels by jays, and of Hazels by squirrels.

The subject of the dispersion of seeds by insects may be most conveniently dealt
with in this connection. Otto Kuntze observed how ants fasten on to the pulp
which surrounds the seeds of Carica Papaya, and push the seeds before them in
companies of three, and Lundstrom narrates that the seeds of the Cow-wheat
(Melampyrum), after they fall out, are carried off to ant-hills. These statements
early directed my attention to the subject of the dispersion of seeds by ants, and I
found that the phenomenon occurs on a very large scale. The ant Tetramorium
cespitum, in particular, is indefatigably engaged throughout the summer in
dragging seeds to the ant-hill and storing them up there. Other species, which
live in holes in the earth, hollow trees, and such places (Lasvus niger, Formica
rufibarbis, &¢.), exhibit this form of activity, but they are much more fastidious
than Tetramoriwm. Many kinds of seed, which are at once pounced upon by the
last-named if they are scattered in the path of those insects, are left untouched
by other species. So far as my observations go, it is the seeds with smooth external
coats, but with large micropylar and hilar caruncles (see p. 425) which are conveyed
to the holes, as, for instance, those of Asarum Europeum and A. Canadense, Cheli-
donium majus, Cyclamen Europeum, Galanthus nivalis, Méhringia muscosa,
Sanguinaria Canadensis, Viola Austriaca and V. odorata, Vinca herbacea and
V. minor, and various species of the genus Huphorbia. The Tetramorium showed
a preference for the seeds of Sanguinaria Canadensis, which possess a very con-
spicuous hilar caruncle. These seeds being comparatively large and heavy, three
or four small ants join forces when one is to be transferred to a hole. There can
be no doubt that the caruncle, affording as it does an easily accessible supply of
food, constitutes the source of attraction to the ants, and induces them to carry off
those particular seeds, Neither the smooth coats of the seeds nor their contents
are touched by the ants. Only thus can we interpret the fact that the seeds

DISPERSAL BY ANIMALS. 867

dragged by ants under the ground, or into erevices in walls, germinate in those
situations in the following year. It sometimes happens also that here and there a
seed is left behind on the route of the ants, and in that case the caruncle is usually
eaten off. Such abandoned seeds likewise germinate in the following year, and this
explains the fact that the routes traversed by ants are regularly planted with
certain species of plants. For example, in the Botanic Gardens at Vienna, the
presence of Chelidonium majus is a constant feature of the ant-runs.

The transport of fruits and seeds to spots more or less remote from the localities
where the mother-plants grow, by animals which have a definite purpose in view
in so conveying them from one place to another, is on the whole a rare means of
dissemination, and is confined to comparatively few species. But the unintentional
dispersion of fruits and seeds by animals is of much more common occurrence.
The objects thus dispersed get stuck or hooked, or otherwise fastened to the animals
in the course of the latter’s wanderings, and sooner or later are got rid of by them
as being an unpleasant encumbrance. The places where such fruits and seeds are
deposited are, however, always more or less distant from the spot where they
ripened, and, as a general rule, they afford favourable conditions for germination.

The adhesion of fruits and seeds to the feathers of birds and to the skin or fur
of other animals is due either to the agency of water, mud, and moist earth, or to
that of special sticky substances secreted by the plants. In the case of many
aquatie and marsh plants, such as jthe genera Alisma, Butomus, Carex, Myriophyl-
lum, Phellandrium, Polygonum, Potamogeton, Sagittaria, and Sparganium, the
fruits and seeds are unprovided either with special organs of attachment or with
viscid secretions, but as was mentioned on p. 847 they have the power of keeping
afloat on the surface of the water. If one dips one’s hand into a pond covered with
floating fruits of this kind, and draws it out again quickly, a number of the fruits
always adhere to the skin by means of drops of water. The same thing happens
when water-fowl rise from the water after swimming about for a time. The beak,
legs, and feathers of a bird that has been shot not infrequently have the fruits in
question clinging to them after the water has run off. If the bird had settled upon
another pond the fruits would no doubt have been transferred to it. Adhesion
through the intervention of water is assuredly by no means an insignificant factor
in the dispersion of fruits to moderate distances.

The agency of mud and wet, boggy earth in affixing objects to animals is espe-
cially efficacious in the case of the numerous small fruits and seeds, which are by
this means caused to adhere to birds when they come to the water’s edge to drink.
Jackdaws, herons, and snipe are not very particular about cleanliness, and they are
invariably found to be smeared with mud. Swallows, particularly the rough-footed
species, are very important members of this category, as during their sojourn on the
banks of rivers and ponds they get bespattered with particles of mud. It is true
that they try to cleanse themselves from all such foreign matter, but when the
season for migration approaches they become restless and excited and forget the
morning toilet which, until then, is performed with great care. In the same manner

868 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

water-fowl when they migrate neglect their usual habit of assiduously removing all
traces of dirt, and we know from the investigations made by Darwin how great is
the number of seeds imbedded in the mud. From 6% ounces of mud 587 plants
germinated. In my own case the examinations of the mud obtained from the
beaks, feet, and feathers of swallows, snipe, wagtails, and jackdaws resulted in about
half as productive a yield of fertile seeds; but that is a sufficiently striking result;
and when it is remembered that pigeons and cranes traverse from 60 to 70 kilo-
metres in an hour, whilst swallows and peregrine falcons cover as much as 180
kilometres, it is clear that fruits and seeds affixed to these birds may be carried in a
very short time over several degrees of latitude. The number of species of plants
which are dispersed in this manner is, it is true, but small. For the most part they
are water-side and of these chiefly small annual species, as is evident from the
following list of those whose fruits and seeds I found most frequently in the mud
taken from birds:

Centunculus minimus. Heleocharis acicularis. Lythrum Salicaria.
Cyperus flavescens. Lsolepis setacea. Nasturtium amphibium.
» Suscus. Juncus bufonius. ” palustre.
Elatine Hydropiper. » compressus, ” sylvestre.
Erythrea puichelia. » lamprocarpus. Samolus Valerandi.
Glaux maritima, LTimosella aquatica, Scirpus maritimus.
Glyceria fluitans. Lindernia pymdaria, Veronica Anagallis.

Most of these species are distributed over all parts of the world, but they seldom
remain for a long time in any particular locality. They often start up quite unex-
pectedly at places where migrating birds have rested and gone to drink. The
extraordinary occurrence on the edges of ponds in Southern Bohemia of the tiny
Coleanthus subtilis, which is indigenous to India, and the sudden appearance of
the same species of grass in the West of France about twenty years ago may be
unhesitatingly attributed to the mode of dispersion in question, as may also the
occurrence of the tropical Scirpus atropurpureus on the shores of the Lake of
Geneva and that of the Southern native Anagallis tenella on the shores of the
Schwarzsee at Kitzbiihel in North Tyrol.

The instrumentality of rain-soaked earth on steppes, on ploughed fields, and on
roads in sticking numbers of fruits and seeds to animals’ feet, whether the latter be
in the form of hoofs, claws, or toes, or to their hair or feathers, as the case may be,
has been the subject of repeated investigation. In the hardened earth taken from
the feet of birds Darwin found a large number of seeds, of which many germinated.
Many weeds which grow on fields and roadsides (Prunella vulgaris, Malva rotun-
difolia, Potentilla anserina, P. reptans, P. supina, Ranunculus sardous, &c.)
depend mainly on this mode of dispersion. According to an informant, the suckers
of the Gecko (a kind of lizard adapted to running about on smooth rocks and walls)
are sometimes beset with fine seeds, and there can be no doubt that certain plants
may be disseminated by sucli means over steep declivities of rock.

The exeretion of sticky substances by fruits and seeds themselves must naturally

DISPERSAL BY ANIMALS. 869

promote their becoming attached to animals, Although the adhesive materials
mentioned in vol. i. on p. 615 as exuding from the fruits and seeds of various Com-
~ posites, Crucifers, Labiates, and Polygonaces when they are wetted may be primarily
devoted to fixing those structures to a substratum where they can germinate, they
also frequently serve a second purpose in sticking them to passing animals, The
best instance of this is afforded by the Meadow Saffron (Colchicum), whose seeds
stick to the feet of cows, sheep, and horses by means of a comparatively large
caruncle, which becomes viscid when it is wetted; in this manner the seeds are con-
veyed from one pasture to another. There is also an instance that has come under
my own observation of a small owl (Athene noctwa), which, in catching mice, brushed
against Wormwood bushes (Artemisia), and when it flew away was all besmeared
with the fruits, which had been rendered sticky by a previous shower of rain. The
succulent berries of Bryonia, Lyciwm, Solanwm, and various other Cucurbitaces
and Solanaceve burst on the slightest touch when they are over-ripe, and sometimes
their seeds stick to the hairs and bristles of passing animals, and it seems not impro-
bable, from the reports of travellers, that the fleshy Rafflesias, which are found
principally on the routes frequented by large pachyderms, are disseminated in the
same manner. The mode of dispersion of the seeds of Nuphar and Nymphea is
also very curious. Their dissemination by aqueous currents has been already dealt
with on p. 848, but they are besides conveyed from pond to pond by water-fowl.
In order to obtain the nutritious seeds these birds break open the fruits of Water-
lilies with their bills, and in so doing are almost sure to leave some of the seeds,
which are imbedded in a slimy mass, sticking to the feathers surrounding their
bills. If they are suddenly disturbed at their meal they have not time to clean
their bills before flying away, and so they carry the seeds with them, and do not
rub them off till they reach another pond. :

The fruits and seeds of several plants attach themselves to any animals that
happen to brush against them by means of special glandular hairs or stalked glands.
These latter consist of round cells or groups of. cells which are borne on stalk-like
structures springing from the epidermis, and which produce on their surfaces viscid,
slimy, and resinous substances (see figs. 476? and 476°). The most diverse parts
may be clothed with stalked glands. In Boerhavia, Adenocarpus, and Pisonia (see
fig. 476 4), it is the pericarp; in Salvia glutinosa (fig. 476+), and the various species of
the genus Plumbago, such as Plumbago Capensis (fig. 476°), it is the calyx; and in
Linnea borealis (figs. 476° and 4767) it is a pair of bracts elosely adherent to the
fruit that is beset with stalked glands. In all these plants an absciss-layer is
formed in the tissue of the fruit-stalk, and as soon as adhesion takes place the fruit
is severed from the plant at the region of this separating or absciss-layer. Many
plants—as, for example, the annual Cerastiwm glutimoswm—have glandular hairs
all over them, and when the seeds are ripe and the plants partially withered and
only loosely rooted in the ground, a touch is sufficient to cause leaves, stems, and
fruits to stick to the hair or feathers of any animal that may happen to pass.
We may add that, in the case of every plant above referred to for illustration, the

870 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

phenomenon in question is not merely a matter of conjecture, but has come actually
under observation.

About 10 per cent of all Flowering Plants possess fruits or seeds which are
dispersed by means of clawed or barbed processes. This mode of dissemination is
very like that whereby sticky fruits attain the same object. The part of the plant
which is provided with these structures hooks on to the hairs, bristles, or feathers
of any bird or other animal that happens to come into contact with it. The conse-
quence is that it is torn away and carried off by the animal. This act of depredation
is of course not intentional on the part of the creature that performs it; on the

contrary, such ms source of discomfort, and are got rid of as soon as

6

ete,

Fig. 476.—Sticky fruits.

1 Salvia glutinosa. 2 Stalked adhesive glands on the fruiting calyx of the same; x60. 8% Plumbago Capensis. * Pisonia
aculeata, 5 Stalked adhesive glands on the fruit of the same; x60. 6 Linnea borealis, 7 Fruit of the same; x5.

possible. But in many cases this is not accomplished until a considerable distance
has been traversed, and sometimes the troublesome objects remain for weeks in the
creature’s coat or mane. The organs of attachment are either hooked at the tip or
beset with barbs (see figs. 477? and 47718), In the latter case the barbs are borne
on special rigid bristles or needles, and are either collected together at the top, as in
a harpoon, or else are arranged in longitudinal rows as in a hackle for combing flax.
Only in a few instances (eg. in Polygala glochidiata, Stellaria glochidiata, and
Limnanthemum nympheoides) do these structures, which may be classed together
as hooked bristles and hooked prickles, occur on the seeds themselves; usually they
are appendages of the pericarp, and as such exhibit every degree of size possible,
from the delicate, hooked bristles on the small nutlets of the Enchanter’s Nightshade
(Curccea, see figs. 477 § and 477°) to the thick, firm claws on the fruits of the African
Harpoon Fruit (Harpagophytwm procumbens). The hooked spines of the latter
fruits attain to the size of crows’ feet, and are a notorious source of vexation to

DISPERSAL BY ANIMALS, 87k

ruminant animals, both wild and tame. In the Transvaal and on the Orange River
the spring-boks sometimes tread upon them unawares, and when that happens the
sharp claws grasp the hoof and the animal is driven to frenzy by the pain and
gallops madly away, but is unable to set itself free from the instrument of torture.
It is often several days before the capsule breaks up and falls off. The fruits, which

Fg. 477.—Fruits furnished with hooks.

1Galium Aparine. ® Hooked bristles of the fruit of the same. % Hedysarum Canadense, 4 A piece of the lomentum of the
same, 5 Hooked bristles of Hedysarum Canad 6 Cynog pictum. 7 Hooked prickles on the fruits of the same,
8 Circeea Lutetiana. ® Hooked bristles on the fruit of the same. 10 Torilis Anthriscus. 11 Single fruit of Torilis Anthriscus.
12 Curved prickles on this fruit. 13 Lappago racemosa. 14 Single fruiting spike of the same, 15 Setaria verticillata.
16 Fruit-bearing branchlet with involucral bristles from a spike of Setaria verticillata. 17 Bidens bipinnata. 18 Single
fruit of the same. 19 Fruit of Caccinia strigosa. 2° Hooked prickles on the fruit of Caccinia strigosa. 2, 4, 5,7, 9, 11, 12,
14, 16, 18 and 20 magnified.

are armed with hooked bristles or prickles, are so numerous that even a superficial
account of them cannot be undertaken here, and we must content ourselves with
mentioning a few of the most remarkable forms. Amongst these are the capsular
fruits of Krameria Ixina and Triwmfetta Plumieri (see figs. 478 and 4781), the
sheathed achenes of several species of Calligonum and Rumez, e.g. Rumex nepalensis
(fig. 478 °), the pods of many Papilionaces (e.g. Medicago agrestis and M. radiata,
Onobrychis equidentata and Hedysarwm Camadense; see figs. 478° and 478°, and

872 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

figs. 477 ® +5), the nutlets of several Boraginaces (e.g. Hchinospermum, Cynoglosswm,
and Caccinia; see figs. 477 ® 7 1 2°), the several segments of the lomenta of Zschyno-
mene patula, the jointed siliquas of Tauscheria lasiocarpa, the schizocarps of some
species of the genera Asperula and Galiwm (eg. Galiwm Aparine; see figs. 4771
and 4772), and the mericarps of many Umbelliferes (Caucalis, Daucus, Orlaya,
Sanicula, Torilis; see figs. 477 111,12, and figs. 478°). Other contrivances exist, but
are much rarer. Such are the bending of the sepals, when the fruit is ripe, so as to
convert the calyx into a claw, as in the genus Rochelia (see fig. 478°), the assump-
tion by the teeth of the fruiting calyx of the form of hooked prickles, as in
Valerianella echinata and V. hamata, Trifolium spumosum, Ballota rupestris, and
Marrubiwm vulgare (see fig. 4781), the presence on the achenes of Composites of
1, 2, 8, or 4 hooked prickles in the place of a feathery pappus, as in Bidens bipinnata
(see figs. 4771” and 47718), the barbed character of some perianth-bristles, as in Scirpus
lacustris, and the crowning of the hypanthium (expanded receptacle) with hooked
prickles, as in Agrimonia (see fig. 478°). As instances of the transformation of
involucral leaves into hooked bristles or prickles, we may mention Xanthium and
Lappa (see figs. 478 and 4781”); whilst Oryza clandestina, Paspalum tenue, and
Lappago racemosa (see figs. 47718 and 4771*) may be taken as representatives of
the Grasses whose glumes are furnished with similar appendages.

Sometimes the entire fruit has the appearance of a claw, or is armed with large
barbs, by means of which it attaches itself to passing animals. This form of adapta-
tion is especially striking in the pods of Krameria triandra, Ornithopus, Biserrula,
Coronilla scorpioides, and Scorpiurus sulcata (see fig. 478 *). The achenes of several
‘Composites (e.g. Rhagadiolus stellatus and Koelpinea linearis) are claw-shaped, and
Koelpinea linearis is provided in addition with a crown of sharp, curved barbs at
the free extremity of each limb of the claw. In several species of the genus Geum, .
of which Gewm wrbanuwm will serve as an example (see figs. 478 and 4781), the
terminal portion of the segmented style breaks off when the fruit is ripe, and the
remaining part becomes converted into a hooked spine which attaches itself to any
object that happens to touch it. Similarly, hooked structures are developed from
the styles of several Ranunculaces and Pedaliacesw. Of the latter the most note-
worthy are the fruits of Martynias (Martynia lutea, M. proboscoidea, &c.), which
detach themselves from the herbaceous stem when the fruit is ripe—the stem being
by that time in a decaying condition—and lie loose upon the ground. Two long
curved clasps, with sharp hooked ends somewhat like the horns of a chamois in
form, are developed from’ the styles, and by means of these the fruits cling to the
feet of animals which tread on them. Indeed the whole family Pedaliacex is of
interest on account of its multifariously hooked fruits. ‘In addition to Martynia
the already mentioned Harpagophytwm belongs here, and several other genera,
including a Chinese aquatic, Trapella sinensis. In this plant the fruit is provided
with 3 long appendages wound up like watch-springs, which must readily hitch
themselves on to the legs of aquatic birds—or possibly even to Fishes—and in
addition 2 shorter, sharp, stiff spines, which no doubt preserve the fruits against

DISPERSAL BY ANIMALS, 873

being eaten. Rogeria and Pedalium, mentioned on p. 875, also belong to this
family.

In other plants it is the fruit-stalk instead of the style which is transformed
into a claw-like structure. In Cyclamen Euwropewm, for instance, the fruit-stalk
undergoes spiral torsion and eontraction. Formerly it was supposed that the object
of this curious phenomenon was to draw the fruits into the earth, where the seeds
would be favourably situated for germination. But this idea does not correspond
to actual fact. The green capsules are drawn underground in the late autumn

Fig. 478.—Fruits with hooks,

' Marrubium vulgare. % Medicago agrestis. % Rumex nepalensis. 4 Scorpiurus suleata. 5 Agrimonia odorata. 6 Orlaya

grandiflora. 7 Pteranthus echinatus. 8 Rochelia Persica. » Onobrychis equidentata. 10 Triumfetta Plumieri. 11 Hooked

_ bristles on the fruit of Triumfetta Plumiert magnified. 12 Medicago radiata. 18 Xanthium spi 14 Ceratocephalus
faleatus. 15 Geum urbanum. 16 A single fallen fruit of Geum urbanum. 17 Lappa major.

when the seeds are still unripe. They pass the winter in the earth, and do not
attain to complete maturity until the following summer. The desiccation and
severance of the twisted fruit-stalk then has the effect of pulling the fruit out of
the ground again, the lower portion of the stalk rots, and the part which is left
forms a claw surmounting the capsule. The latter, which is still full of seeds, lies
loose on the ground, and adheres to the foot of any animal that treads on it. The
manner in which these seeds are besides dispersed by ants has already been referred

to on p. 866.

874 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

With this curious form of fruit we may associate those in which the claws or
hooked prickles are metamorphosed branches, or parts of abortive flowers situated
on special ramifications. It will be sufficient to adduce two examples of this group,
viz., Pupalia atropurpurea, of the family Amaranthacee, and Pteranthus echinatus
(see fig. 4787) of the family Paronychiaceew. In Pupalia atropwrpwrea short
branchlets spring from the axils of the bracts; a few of them bear fruits, whilst the
majority are modified into hooked prickles and form a tuft which easily fastens on
to foreign bodies, and becomes detached from the main axis, Pteranthus echinatus
has several short branchlets in each inflorescence situated close to the fruit, and
bearing at their extremities abortive flowers with hooked sepals.

A) ARGH
Fig. 479.—Fruits which hook on to or stick into passing objects.

) Carex microglochin. 2Single fruit of the same. 2% Galium retrorsum. 4 i
; : . . 4A piece of the stem of the same. 5 Carex
Pseudocyperus. 6 Single fruit of the same. 7 Triglochin palustre. ®Single unripe fruit of the same. 9 Transverse
section through the same fruit. 10 Single ripe fruit with its component valves separated, 2, 4, 6, 8, 9 and 10 magnified.

All the clawed or prickly fruits and clusters of fruit above enumerated
easily come away from the mother-plant when pulled by the objects to which they
have attached themselves. But there are other cases where the hooks and claws are
firmly attached to the axis of the plant as a whole, so much so indeed that if the
object to which they are fastened gives a pull a large piece of the stem is torn away,
and sometimes even the entire plant is uprooted and carried bodily away. To this
class belong the fruits of several Rubiacex, of which Galiwm retrorsum (see figs, 479%
and 479 *) may be taken asa type. The fruit-bearing stem of this plant is at once
broken off or uprooted when its barbed bristles catch in the coat of a passing animal.
The species of the genus Uncaria also are examples of the kind. The long, creeping
stems develop here and there clusters of fruit and at other spots abortive peduncles,
which are metamorphosed into strong, sharp claws. When these claws get hooked
to an animal’s foot, a more or less large piece of the stem is torn away, and with it

DISPERSAL BY ANIMALS, 875

the fruits developed upon it. Again, in Specularia falcata, Valerianella echinata,
Cornucopia cucullata, and Ceratocephalus falcatus (see fig. 4781) the fruits do not
sever themselves from the stems when their claws become attached to animals, but
the entire plant is uprooted and carried away. A similar phenomenon is observed
when a fruiting plant of Setaria verticillata is touched by one of the larger birds
or some other animal. The fruits of this Grass are wrapped in awnless glumes
and surrounded by involucral bristles furnished with very sharp barbs (see figs.
477° and 477"). When the bristles get fastened to an animal, not only the fruiting
spike, but often a piece of the haulm as well, is dragged away, and sometimes the
entire plant is uprooted and taken off Such fortuitous appendages are very
troublesome to the animal, and are got rid of as soon as possible. In many instances
this is achieved without great difficulty by rubbing the coat against fixed objects,
or by using the feet, snout, or beak, as the case may be, to disembarrass the body.
Sometimes, however, the sharp claws and barbs of the fruits are so firmly imbedded

Fig. 480. — Fruits with needle-like spines.

1 Pedalium Murex. 2 Tribulus orientalis.

or entangled in the hair or feathers that their extrication is attended with much
difficulty and suffering.

A mode of fruit-dispersion involving still greater pain to animals is that which is
accomplished by means of straight, smooth prickles projecting from the fruit, and so
situated as either to bore into the foot of any animal that treads upon it, or to stick
into the coat of one that merely brushes by. Two groups of these fruits may be distin-
guished. The first group comprises those which lie loose upon the ground when they
are ripe. To it belong Acicarpha, Ceratocarpus, Salsola, and Spinacia, in which the
tips of the fruiting calyx harden and are transformed into spines standing straight
up, and also Rogeria, Pedalium, and Tribulus (see figs. 4801 and 4807), in which
the spines project from the fruit-walls. One of the species of the last-named genus,
viz., Tribulus orientalis, is of common occurrence in the lowlands of Hungary, and
is an object of dread to the shepherds of that region. The fallen segments into
which the fruit resolves itself are armed with hard, sharp, comparatively long
spines, and are often so covered with drifted sand that only the tips of the spines
project above the surface (see fig. 4807). These prickles pierce deep into the hoofs
and soles of animals that tread upon them, and are broken off the fruit by the
efforts of the latter to rid themselves of the impediment. They are thus left sticking
in the skin, and cause very painful, festering wounds. As examples of the second
group of fruits furnished with sharp prickles as instruments of dissemination we

876 THE DISPERSION OF SPECIES BY MEANS OF FRUITS AND SEEDS.

may take those of Carex pauciflora and Triglochin palustre (see figs. 479 1, % 7, 8 % 10)

These fruits are borne on a stiff, erect axis, and when ripe are pointed obliquely
downwards. They easily become detached from their stalks and are left sticking
like needles in the skin or fur of animals that touch them.

Straight or slightly curved bristles and prickles may take part in another way
in the dispersion of fruits. When they are set in rows like the teeth of a comb on
the surface of a fruit or stand out in pairs from it, as, for instance, in Carex
Pseudocyperus (see figs. 479° and 479°), the woolly hairs and delicate feathers of
some animals are liable to get entangled in them, and they are then dragged from
their stalks, The same thing happens where the prickly processes projecting from
the fruit cross one another, as in Pterococcus, Sycios, and many species of the Medick
genus (eg. Medicago ciliaris, M. littoralis, M. spherocarpa, M. tentaculata, and
M. tribuloides), and where the surface of the fruit or of the fruiting calyx is
covered with stiff bristles forming acute angles with it, as in Asperugo, Myosotis,
Parietaria, Physocaulis, and Torilis (see figs. 47719”). In many Grasses the
awns which project from the backs of the glumes act as instruments for catching
the hair of animals as they pass, and the latter is also liable to get caught between
the nut and the hardened perianth-segments which surround it in several Chenopo-
diaces. It is not necessary for this that the bristles, prickles, or awns should be
pointed, but it is advantageous for their surfaces to be rough or jagged, as in Torilis
(see fig. 477), We must not omit to mention also that the tufts of hair which
clothe some fruits and seeds, and act as parachutes and wings, often get entangled in
the hair or feathers of animals, and thus play an additional part in dissemination.
The rough coats of sheep, goats, oxen, and horses are always found to have such
hairy fruits and seeds affixed to them after they have passed over ground on
which herbaceous Composites, shrubby Willows, &., grow at the season when those
plants are in fruit. I have myself removed from the coats of animals of the above-
mentioned kinds fruits and seeds of Anemone sylvestris and of various species of
the genera Calamagrostis, Crepis, Cynanchum, Epilobiwm, Eriophorum, Lactuca,
Lagecia, Micropus, Populus, Salix, Senecio, Sonchus, and Typha.

Anyone who has forced his way through a thicket of poplars and willows in
early summer or through a clearing overgrown by Calamagrostis, Epilobiwm, and
Senecio in late summer can bear witness to the manner in which fruits and seeds of
the sort in question adhere to the clothes. Sticky and hooked fruits are also found
upon one after such excursions, and it is perhaps not superfluous to remark that
what has been said concerning the dispersion of seeds by animals must be taken to
apply also to dissemination by men. Of course we are here referring to wninten-
tional dissemination by human agency. We are here concerned with the cultivation
of corn, vegetables, garden-flowers, edible fruits, forest-trees, &c.—i.e. with the
purposeful dispersion of plants by men—in so far as many of the species in ques-
tion establish themselves beyond the limits of the fields or gardens, where they have
been sown or planted by man, through the operation of their natural means of dis-
semination and without human assistance, and further, inasmuch as weeds are often

RETROSPECT, ‘877

introduced into the soil unawares with the seeds of other plants, and so grow in

places where they would scarcely ever obtain a footing without the interference of
mankind.

Looking back over this chapter we are struck by the following points:—In the
first place, the commonest contrivances and adaptations are those which confer some
other benefit in addition to that of dispersing fruits and seeds. The kind of struc-
ture most often encountered in this connection serves first as a means of protecting
the flowers against unbidden guests of the animal kingdom and against injurious
climatic conditions, subsequently as a means of scattering the fruits, and lastly, is
instrumental in attaching them to a substratum and in promoting germination.
Moreover, it appears from what has been said concerning pappuses and tufts of hair,
that it is no rare thing for contrivances to be adapted equally well to the dispersion
of fruits and seeds by the wind, by water, or by animals. It is also of great
moment to observe that most, and perhaps all, Phanerograms exhibit two methods
of disseminating their fruits and seeds, one of which is adapted to considerable dis-
tances, whilst the other is confined to the immediate vicinity of the mother-plant.
The former may and does, as a fact, take place on a vast scale, but it depends upon
the circumstances of the environment over which the plant itself has no control. It
may, therefore, in some circumstances, be completely suppressed; in other words,
dispersion to a great distance may take place but does not necessarily take place.
Just as the best-made machine stands still unless its wheels are set in motion by an
impulse from without, so the development of the most perfect flying apparatus is of
no avail if there is an entire absence of wind at the time when the winged fruit is
ripe; nor do the strongest hooks serve as means of dispersion if no animals come
upon the scene. On the other hand, dissemination within short distances of the
mother-plant always takes place if wider dispersion fails. Supposing the fruits of
a Maple-tree, when ripe, are not blown far away by a strong gust of wind, they are
ultimately detached spontaneously, and drop with a gyratory motion to the ground
close by the tree which produced them. Again, in the case of the Squirting
Cucumber, should the expulsion of the seeds from a fruit be caused by the touch of
an animal, and the seeds stick to the latter’s coat, they may be carried to a distance
of many miles, but if no animal happens to pass the spot where the Cucumber is
‘growing at the time when the seeds are ripe the latter are spontaneously ejected,
and the dispersion so effected does not exceed a few paces in distance. In the event
of the fruits of Cyclamen (see p. 873), which are borne on twisted claw-shaped
stalks, not being carried away by animals, they remain lying on the ground in
immediate proximity to the mother-plant and the seeds germinate in that situation.

These examples, to which might be added many others, show that the same
law governs the contrivances adapted to the dispersion of fruits and seeds as was
found to apply to the pollination of stigmas (see p. 390). Every species of plant
exhibits some mechanism designed to bring about a cross with another species, or,
at any rate, with another individual. If such mechanism is unsuccessful, other

878 LIMITS OF DISTRIBUTION.

contrivances are brought into play, the aim of which is to accomplish autogamy.
The open flowers of Viola sepincola are adapted to cross-pollination through the
agency of bees; should no cross take place, and no fruits be produced from the open
flowers which bloom above the ground, cleistogamous flowers, hidden under-
ground, develop and bring forth a number of fertile seeds as a result of the auto-
gamy which inevitably takes place within their closed floral envelopes. Viola
sepincola may also be taken as a type of those plants in which the fruits ripen
underground and produce seeds which germinate at the spot where they were
formed. Such plants have always been a source of wonder to botanists, and their
number is not large. The best-known examples are Arachis hypogea, Cardamine
chenopodiifolia, Linaria Cymbalaria, Phryniwm micans, Trifolium subterranewm,
and Vicia amphicarpa. If these plants were only to bring fruits to maturity
underground, or were to draw all their fruits below the ground as soon as the
seeds were mature, in order that germination and the development of new plants
might ensue at that spot, their behaviour would imply a renunciation of dispersion
to any distance, and the phenomenon would be highly enigmatic. The puzzle is,
however, satisfactorily solved when we take into account the fact that all these
plants invariably have the chance of being dispersed to great distances either
before the fruits become concealed in the earth, or by means of a second form of
fruit which ripens above ground, and is evidently adapted to being scattered abroad
through the agency of animals, or by means of aérial or aqueous currents.

LIMITS OF DISTRIBUTION.

The results of careful computations of the numbers of seeds produced yearly
by a few selected plants show that on an average a plant of Sisymbriwm Sophia
yields 730,000, one of Nicotiana Tabacwm 860,000, one of Erigeron Canadense
120,000, one of Capsella Bursa-pastoris 64,000, one of Plantago major 14,000,
one of Raphanus Raphanistrwm 12,000, and one of Hyoscyamus niger 10,000.
Each of these seeds may give rise in the following year to a new plant, which,
in its turn, may produce a corresponding number of seeds. Accordingly, if a
Henbane-plant developed 10,000 seeds in one year, and 10,000 plants sprang from
those seeds next year, and themselves produced 10,000 seeds each, by the end of
five years ten thousand billions of Henbane-plants would have come into existence.
Now, as the entire area of the dry land on the earth is approximately one hundred
and thirty-six billion of square metres, and there is room for about 73 Henbane-
plants on one square metre, if all the seeds referred to in our hypothesis ripened,
the whole of the dry land would, at the end of five years, be covered with the
plants in question. In the case of Sisymbriwm Sophia, the normal multiplication,
if unchecked, would, in the course of three years, cover an area 2000 times as great
as the surface of the dry land with plants.

Any such exclusive occupation of the entire earth by one or a few species is
prevented by a variety of causes. As regards land-plants, the sea, separating,one

PHYSICAL CARRIERS, 879

country from another, constitutes an important barrier to unrestricted distribution.
Even narrow straits form an insuperable obstacle to any mode of dispersion which
proceeds step by step, whilst broad seas also interfere with the dissemination per
saltwm, which is accomplished by roving animals and by currents of air and water.
The number of species capable of being transported across the sea by birds is so
small, that the dispersion of plants as a whole is not appreciably affected by this
process. The same remark applies to dissemination by water. It is well known
that fruits and seeds of American plants are occasionally conveyed to Europe by
the Gulf Stream, and Linnzus tells us how the seeds of the West Indian Filbert
(Entada Gingolobium) germinated after being stranded on the coast of Norway.
There is no need to point out that tropical plants of the kind would not be able to
establish themselves permanently in Western Europe were it only for the nature of
the climate. But even amongst other American plants to which the climate would
be no drawback, not a single species is known to have come to Europe by water
without human intervention. Nor has any fruit or seed achieved the crossing of
the ocean to Europe through the medium of the air. America possesses a large
number of Willows, Composites, and Onagracee of her own, which have their fruits
and seeds exquisitely adapted to aérial flight, and are themselves well fitted to
thrive under the climatic conditions of Europe. Nevertheless not a single instance
is recorded of such a plant migrating from America to Europe through the agency
of the wind. The Composite and Onagracee, which have become naturalized in
Europe since America was discovered (e.g. Hrigeron Canadense, Galinsoga parvi-
flora, Solidago Canadensis, Stenactis bellidiflora, Enothera biennis, &e.), were
introduced in other ways, and would neither have established themselves nor have
been disseminated in Europe without human intervention.

The fact that a considerable number of American plants have found a home in
Europe through the agency of man alone, and independently of the movements
of birds or currents, is of great interest in connection with the present subject,
inasmuch as it shows that the limits of distribution imposed by the sea are only
temporary, that is to say, they are only maintained so long as the present distribu-
tion of land and water remains unaltered. If Europe and America were to become
connected by a bridge of land, the possibility would arise of a gradual or sudden
migration across the bridge, and such plants as have been conveyed from America
to Europe by human agency would be able to immigrate without such assistance,
and to disseminate themselves over Europe. The external conditions would offer no
impediment to their naturalization in Central Europe any u.e than they now do
to the installation of the same species when introduced by man. As the sea limits
the distribution of land-plants, so the dry land restricts the dispersion of marine
plants. The larger the expanse of land between two seas, the more difficult is it for
the plants which inhabit them to exchange their homes. But here again the barrier
is merely temporary; for were the land to sink in any part so as to become sub-
merged, and the two seas thus become confluent, there would be nothing to prevent
the plants living in them from passing from one to the other.

880 LIMITS OF DISTRIBUTION.

The nature of the soil may constitute an insuperable obstacle to a permanent
occupation of a particular district by plants, and so act as a check to dispersion.
Everywhere localities with sandy, loamy, or rocky subsoils alternate with loose, wet,
‘and porous argillaceous earths. And yet how utterly different are the conditions
under which plants growing on these two kinds of soil respectively must exist. Let
us consider the case of a particular species, whose seeds are uniformly scattered
over a district which includes areas with different kinds of soil. In the parts where
the ground possesses the requisite properties for the maintenance of the species in
question, the seedlings are able to establish a firm footing, whilst those seeds which
fall on uncongenial soil perish. If millions of fertile seeds belonging to-a marsh-
denizen were scattered over a dry tract of land, not a trace of them would be found
at the end of a twelvemonth. The extent to which the chemical in addition to
the physical properties of the soil operate, in producing this result, and the part
played by competition between different plants for possession of the ground, have
been already dealt with (p. 495 et seqg.). From these observations it is obvious
also that the distribution of species, even within a district of restricted area, is
materially influenced by the soil, and that the spots in such a district where a
particular species thrives and multiplies are divided from one another by tracts
where it does not exist. Those restricted sites in a locality, which offer favourable
conditions to the progress of a particular species, and allow of its posterity main-
taining possession of the soil, where, indeed, the species is permanently established
are called the habitats of that species. The botanists of former times distinguished
such habitats into a large number of different classes, from which we may select the
following as the most important: fresh-water springs ( fontes), salt springs (salina),
brooks (amnes), torrents (torrentes), rivers ( fluviz), pools (stagna), lakes (lacus), the
sea (more), shores of rivers and lakes (ripe), sea-coasts (littora), marshes (uliginosa),
swamps which dry up in the summer (paludes), peat-bogs (twrfosa), places that are
periodically flooded (inundata), pastures (cami), steppes (pascua), deserts (deserta),
sunny hills (colles), stony places (Lapidosa), rocky places (7upestria), sands (arena),
argillaceous soil (argilla), loam (lutwm), débris (ruderata). Sufficient has been said
to prove the fact that these habitats undergo various displacements, and are some-
times entirely lost, in consequence of changes effected in the soil in course of time
through the action of running water and aérial denudation, or in consequence of
the accumulation of humus,

The most potent influence affecting the dissemination and distribution of plants
is that exercised by climate. The length of the days and corresponding duration of
the sun’s illumination, the temperature of air, ground, and water at the different
seasons of the year, the condition of the atmosphere in respect of moisture, the
quantity of water deposited by the atmosphere, and the times at which such deposi-
tion occurs in each year, the strength and direction of prevailing winds—not only
are all these circumstances in general of the greatest moment to plant life, but each
climatic factor stands in a definite relation to each species. If the fruits or brood-
bodies of a plant are carried by any of the usual agencies of dispersion to a place

CLIMATE AS A BARRIER. 881

where the soil is favourable, but where the intensity of light, of warmth, or of
moisture exceeds or falls short of the right measure for that particular species, the
development of the species is arrested at the outset, and the plants die without
leaving any offspring behind them. In this manner an absolute barrier is opposed
by climatic conditions to the dispersion of each species. It must be added that the
check may be given in one direction by one factor and in another direction by another
climatic factor, and that not infrequently many conditions, collectively classed under
the name of climate, exercise a simultaneous influence on the distribution of species.

The limits to the range of plants towards the Arctic and Antarctic regions and
towards the summits of high mountains are imposed by the diminution of tempera-
ture and the increasing length of the winter, whilst the opposite boundary is
encountered where the duration of daylight is still too short at the time of year
when the temperature begins to be sufficient to cause the plants in question to
sprout. The continental climate, which is distinguished by slight degrees of mois-
ture, high summer temperatures, and low winter temperatures, checks those plants
which suffer from dryness in summer or which cannot endure the cold of winter.
On the other hand, in the case of species whose transpiration is unduly checked by
a high degree of atmospheric moisture and which require an elevated temperature
in summer in order to bring their seeds to maturity, bounds are set to dispersion by
the climate of the sea-coast where comparatively slight variations of temperature
occur during the year and where the summers are cool and the air damp. Meteoro-
logists show us on special charts the distribution of the climatic factors by connecting
all places having the same mean winter temperature, the same mean summer tem-
perature, the same mean annual deposition of moisture from the atmosphere, and so
forth, by lines which are termed isocheimal, isotheral, and lines of like mean annual
rainfall respectively. The distribution of plants, in so far as it depends on climatic
conditions, may be shown in the same manner by drawing lines connecting all the
places at which any species is checked by climatic conditions. Such lines are called
lines of vegetation, and when they run along the slopes of a mountain they coincide
with the contour-lines. As each species of plant is checked in its progress towards
the different quarters of the compass by different factors of climate, lines of vegetation
may be drawn corresponding to the limits of range for each species to the north,
north-east, east, south-east, south, &c. When all these vegetation-lines of a species
are connected we obtain a curve which returns upon itself and is called a line of
distribution. In most cases this line resembles an ellipse with the longer axis lying
in the direction of the parallels of latitude. It is, however, not infrequently modi-
fied by influence of the nearest lines of sea-coast. The proximity of mountains also
may cause variations which are principally of the nature of sinuses or bulgings.

The line of distribution incloses therefore the entire area of distribution in which
the species in question finds suitable conditions and in which as a fact it grows and
multiplies. Emphasis must be laid on the latter circumstance, because experience
has shown that a plant-species does not necessarily grow in all the places where the

conditions are favourable to its existence. Only the boundary-lines of the area of
Vou, II. 106

882 LIMITS OF DISTRIBUTION.

distribution are dependent at the present day on climatic conditions; the manner in
which the species has come to occupy that area has not been determined by the
existing climate, but by geological processes which have always been the cause of
the migrations of plants on a large scale. It also becomes a question in each
individual case to what extent under past and present conditions the means of
plant-dispersion would have free play.

The different areas of distribution vary greatly in size. Many species are only
encountered on a single mountain, or in a particular valley, or on one island, as the
case may be. These are called endemic species. As examples of such endemic
species from the regions of Southern and Central Europe we may mention the
following: Iberis Gibraltarica (Gibraltar), Huzomodendron Burgeanwm (Central
Spain), Dioscorea Pyrenaica (Central and Eastern Pyrenees), Sawifraga florulenta
(Liguria and Piedmont), Saponaria lutea (South-western Alps), Heracleum alpinum
{the Jura), Hieraciwm Grisebachii (the Oetzthal in the Central Alps of Tyrol),
Daphne petrwa (Val Vestino), Rhizobotrya alpina (Fassa and Belluno), Gentiana
Frélichwa (Carniola and Carinthia), Wulfenia Carinthiaca (Carinthia), Sempervivum
Pittoniz (Serpentine mountains in Upper Styria), Schiverekia Podolica (Podolia),
Viscaria nivalis (Roduna Gebirge, in Northern Transylvania), Pedicularis lamnogena
(Bihar Mountains), Hepatica Transsylvanica (Southern Transylvania), Haberlea
Rhodopensis (Rhodope Mountains in Roumelia), Jankea Heldreichit (Thessalian
Olympus), Helichrysum virginewm (Mount Athos), Campanula Aizoon (Mount
Parnassus), Hypericum fragile (Kubcea), Globularia stygia (Mount Khelmos),
Genista Melia (Melos), Cephalanthera cucullata (Crete), Centawrea crassifolia
(Malta), Petagnia saniculifolia (Sicily), Lereschia Thomasii (Calabria), Batatas
sinuata (Ischia), Helichrysum frigidwm (Mountains of Corsica).

The species contrasting with the endemic as regards distribution, .¢. those whose
range extends over almost the whole of the plant-inhabited earth, are called cosmo-
politan. Their number is very small.

Only in the case of endemic species occupying an extremely restricted area do
we sometimes find the plants evenly distributed over the whole area. They are
more usually scattered unequally over the district in question. The spots where
they grow in large numbers close together are separated by tracts where they do not
grow at all, but where other species have taken possession of the soil, and the line
of distribution then incloses separate habitats which are often at a considerable
distance from each other. In such cases we speak of the area of distribution as
sporadic. How far this depends on properties of the soil has been explained on
pp. 495-500, and we need here only add that in mountainous or hilly countries
the degree and direction of the inclination of the ground may have an important
influence. Owing to the fact that a slope receives very different amounts of light
and heat according as it faces north or south, different parts of a single mountain
may exhibit diversities in respect of temperature and moisture as great as exist on
flat ground between places separated by a degree of latitude. Also the differences
in meteorological conditions between slopes facing east and west respectively, and

PLANT-MIGRATIONS, 883

particularly those with south-east and south-west aspects, are much greater than is
commonly supposed, and species are known, for example, which in a particular
district invariably have their habitats on south-east slopes, whilst others occur only
on slopes facing south-west.

Tt has been stated that the geological phenomena, and the changes of climate
connected therewith, have at all epochs exercised an important influence on the
migrations of plants, and have consequently had much to do with the displacements
that have occurred in the lines of distribution. If a change occurs which results in
the climatic conditions of 48° north latitude becoming such as previously prevailed
at 46° north latitude, those species of plants whose range extended northwards as
far as 46° proceed to take possession of suitable habitats beyond that limit and the
northern line of vegetation of those particular species is sooner or later shifted north-
wards. On the other hand, the species which had up to that time enjoyed favourable
conditions at 48° north latitude, but can no longer flourish under the new conditions,
establish themselves on more suitable habitats lying further north, so that their
southern line of vegetation undergoes displacement northwards. The eastern and
western lines of vegetation may also be shifted in accordance with such alterations
of climate as occur when an inland locality is converted into a maritime site or vice
versa. These displacements may assume the aspect of a progression or of a retro-
gression, but in every instance the abandonment of the area of settlement will
take the form of a migration of the plant-species concerned.

These migrations of plants which are accomplished independently of human
influence take place as slowly or as quickly as the changes of climate to which they
are due. In the case of species only capable of flourishing on particular habitats
colonization must naturally proceed by leaps and bounds, whilst retrogression also
cannot possibly take place uniformly.

The numerous habitats occupied by a species within the limits of its area of
distribution are scarcely ever exactly alike in respect of the conditions which
influence plant-life. Some habitats are pre-eminent on account of their advantageous
position. The species in question develops most robustly, and multiplies most

‘abundantly in that habitat. In the event, too, of a change of climate the species
continues to live there longer than elsewhere, and may succeed in clinging to such
isolated spots under fundamentally altered climatic conditions long after it has died
out from hundreds of other habitats in the neighbourhood. If the species has
meanwhile transplanted itself to adjoining territory and established there a fresh
area of distribution, the spots where it has managed to survive in the old country
appear like lost outposts wrested from the main area of distribution, or like islands
lying off the shores of a continent. Such a state of things is by no means uncommon,
and we are able to deduce therefrom facts not only concerning the former condition
of the vegetable world, but also concerning the climatic conditions which used to
prevail and as to the directions in which, in due course, plant-migrations have taken
place. We shall have an opportunity to return to these interesting cases in the last
chapter of this volume.

f

884 LIMITS OF DISTRIBUTION.

It is of great interest to note that the so-called “petites espéces” (see p. 581) of a
particular genus often suppress and replace one another in adjacent regions and
climatic zones. The first idea which suggests itself to one observing this phenomenon
is that the differences of form exhibited by these races in neighbouring districts are
the direct result of the diverse conditions of soil and climate under which they exist,
and in former times this was the general opinion of botanists. Even at the present
day many botanists hold the view that when a plant-species reaches a place where
the climatic conditions differ from those of the home it has till-then inhabited, it is
able to adapt itself to the new environment, that such adaptation takes the form of
an alteration of form, that the change is inherited by the plant’s offspring, and that
in this manner new species arise. But the results of experiments made on purpose
to determine this matter do not justify any such opinion. No success has attended
efforts to bring back various “ petites espéces” to one and the same form by cultiva-
tion under precisely similar conditions, nor has any one of those species undergone
the anticipated transformation on being transferred to the external environment
which was looked upon as the cause of the variation in question. Hither the species
subjected to the new conditions succumbed thereto and perished without leaving
any offspring, or else it underwent such alterations in form as are usually considered
to be indicative of varieties merely (see pp. 508-514). These changes were not
inherited by the offspring, and no “petite espéce” has ever arisen from a variation
caused by properties of soil or climate. Such characteristics as are preserved by
heredity, and constitute the essence of a species can therefore only have made their
appearance, even in the case of “petites espéces”, as a result of crossing. Whenever
characteristics produced by a cross were in harmony with the climatic conditions of
a district, the survival of the form which possessed those characteristics was assured.
Such a form would be able to acquire through its offspring an area of distribution
exactly co-extensive with the appropriate conditions of soil and climate. The two
old species from which the new one sprang may both remain in the neighbourhood;
it is, however, possible for one only of them to survive, and it is also conceivable
that both should have died out. We must not forget in dealing with this question
that the age of most species is much greater than was formerly considered possible,
that in the case of the majority of species repeated displacements of the area of
habitation have taken place since the species arose, that in the course of these
displacements the species which belong to a single original stock, and are therefore
allied in respect of the history of their evolution, have often been separated from
one another, and that a proportion of them have perished and vanished altogether
from the scene.

So long as two areas of plant-distribution, formed in adjacent zones or regions,
do not touch anywhere, intercrossing between the denizens of those areas is very
difficult, if not impossible, and even the “ petites espéces” persist unchanged under
such circumstances, and preserve their specific characteristics in their offspring. But
even where the areas of distribution adjoin one another, and the distance between
their native species constitutes no hindrance to cross-pollination, it is still possible

*

PLANT COMMUNITIES AND FLORAS. 885

for two or more species to remain sharply marked off from one another owing to the
fact of their flowering at different seasons. If the flowers of one species are already
over when the other begins to bloom, no cross can take place between them under
natural conditions. This obstacle to cross-pollination, which has been termed
asyngamy, is the cause which enables very similar species sometimes to live close
together without producing hybrids, and thus prevents the origin of new inter-
mediate forms. For example, when Aster Amellus begins to bloom the flowers of
the similar plant known as Aster alpinus are already over in the same locality, and
again, at the season when Solidago Virgawrea unfolds its earliest blossoms, the
flowers of the allied species Solidago alpestris, growing in the same neighbourhood,
have already set their fruits. Such asyngamic species, of which mention has already
been made on p. 510, are therefore found even in localities where their areas of
distribution are contiguous, and even where those areas dovetail into one another,
and where the various “petites espéces” grow together and transmit their specific
characters unaltered to their descendants.

PLANT COMMUNITIES AND FLORAS.

Wherever the reign of nature is not disturbed by human interference the different
plant-species join together in communities?, each of which has a characteristic form,
and constitutes a feature in the landscape of which it is a part. These communities
are distributed and grouped together in a great variety of ways, and, like the lines
on a man’s face, they give a particular impress to the land where they grow. The
species of which a community is composed may belong to the most widely different
natural groups of plants. The reason for their living together does not lie in their
being of common origin, but in the nature of the habitat. They are forced into
companionship not by any affinity to one another but by the fact that their vital
necessities are the same. It may perhaps be true that amongst the many thousands
of plants inhabiting the earth no two are to be found which are completely alike in
their requirements in respect of the intensity and duration of solar illumination, the
concurrence of a particular duration of daylight with a certain amount of heat, the
composition and quantity of the nutrient salts available at the places where the
plants live, the amount of moisture in the air and in the ground, or, lastly, the
character of the rainfall. This does not, however, exclude the possibility that in
particular places similar demands may be met, and that different species with similar
needs may flourish undisturbed side by side as men live together in one house or in
one town, and, although their customs and their needs may not be exactly the same,
yet form a society which is permanent and thrives, and wherein each member feels
at home, because it rests upon common usages and is adapted to the local conditions.
Nor is it impossible that each one may derive an advantage from the common life,

1¢f. A, Kerner von Marilaun “‘ Oesterreich-Ungarns Pflanzenwelt”, in Dre Oesterreichisch-Ungarische Monarchie
in Wort und Bild. Vol. i. p. 185 (1887).

886 PLANT COMMUNITIES AND FLORAS.

that the associated individuals may support one another in the conduct of their
lives, and that they may even be dependent upon one another.

A knowledge of the communities which exist within the realm of plants is of
great, importance in many ways. It throws a strong light, not only on the mutual
relations of the different species which are associated by common or similar needs,
but also on the connection of plant-life with local and climatic conditions and with
the nature of the soil. It may fairly be said that in the various zones and regions
of our earth no kind of phenomenon so thoroughly gives expression to the climate
and the constitution of the soil as the presence of particular plant-communities
which prevail, and, accordingly, the determination and description of such communi-
ties constitutes an important part of geography. Hitherto, it is true, only a few
investigators have paid attention to this subject, and even they have given it but
moderate study, the reason being probably that for the determination and description
of plant-societies comprehensive data concerning all the species which flourish in the
district under investigation are requisite, and the acquisition of such data has been
greatly neglected of late years owing to the paramount attractions of other depart-
ments of Botany. The small progress of our knowledge in that direction is due also
in part to the circumstance that a uniform method of investigating, describing, and
classifying plant-communities has not up to the present time been successfully
instituted.

The first thing that strikes anyone who takes up this subject is the fact that the
different species of plants play very unequal parts in the formation of communities.
Certain species predominate in respect of the number of their individuals. They
determine the general character of the community, and form the groundwork of the
vegetation as a whole, whilst the rest only make their appearance here and there,
and look as though they were merely intercalated in the groundwork. It stands to
reason that such dominant species, as they are called, belong chiefly to those which
by nature grow together in numbers, and that those in particular are the most
conspicuous which are aggregated together on a large scale.

Having regard to the dependence of plants upon soil and climate, the nature of
which has been fully set forth in the first volume of this work, it might be expected
that all plants living under identical conditions would have a common aspect or
physiognomy. But this idea is only confirmed in the case of dominant species.
The subordinate species may differ from the dominant ones, and also amongst
themselves. One of the most usual causes of such differences of form is that the
subordinate species of a community pass through the processes of budding, flowering,
and fruiting at different seasons relatively, and that one species is adapted to the
conditions which prevail in the spring, another to those of summer, and a third to
those of autumn. It may also happen that certain reciprocal advantages accrue to
neighbouring members of a community from the variety in the forms of their stems,
foliage, and flowers. If one species affords at the right moment the shade required
by another, or serves as a support for it to climb up, or protects it from high winds,
such assistance not only does no harm to the community, but, on the contrary, con-

TYPES OF PLANT-COMMUNITIES. 887

tributes materially to its preservation; and the same may be said of the cases where
. contrast: between the colours of the flowers of adjacent species promotes visits from
insects, or where any other mutual help is afforded by plants growing side by side
in a community. The general aspect of a community is scarcely influenced at all
by diversities in the nature of the subordinate species, but depends solely on the
dominant species which enter into its composition. These stamp their characteristic
aspect upon the entire community, and determine the general impression conveyed
to the observer.

This fact is.of great moment when we come to the task of identifying, classi-
fying, and naming the various communities: formed by plants. Not only must the
gregarious dominant species afford the basis of description in the case of each
separate community, but their external appearance is the most important means of
classifying in groups, according to similarity of aspect, the numerous communities
which have been formed in the present period of the earth’s history. Observations
made under natural conditions, and extending over many years, have led to a
division of plant-communities into the following nine groups:—

I. Forests—The dominant species are plarits with standard stems (see vol. i.
p. 712). In accordance with the common notion of a forest, the stems which con-
stitute its substructure are destitute of branches or leaves up to a certain height.
Where this height is not much above that of a man, we speak of a copse; but if
the standard stems remain branchless and leafless to a greater height, the assem-
blage of plants is called a forest proper. We might call these two kinds of forest
(for the purposes of this chapter) high forest and low forest, though the terms
are not in all ways free from objection; further, the circumstance that high forest
has been low forest in the younger stages of its development is an additional reason
against their adoption. If the trees of which a wood is composed are so close
together that their top leaves and branches are in contact and form a sort of roof,
the wood is said to be crowded or dense; whilst, if the trees are so formed and
situated relatively to one another as to allow the rays of sunlight to penetrate
between them and reach the ground, the wood is said to be thin.

II. Scrub.—The dominant species are shrubs, semi-shrubs, and cactiform plants
growing in thickets, and never developing standard-stems, but branching from the
very base, even when full-grown. The transition is quite gradual from erect scrub,
reaching to a height of 2 or 3 metres, to those in which the stems lie upon the

ground, and only lift their woody branches a few decimetres above it. It is the
nature of shrubs and semi-shrubs to form thickets. Most of the bigger shrubs are
impenetrable if not modified by human agency. In special situations, and under
certain annually recurring conditions, woody plants of a kind, which usually develop
into trees and exhibit standard-stems, may be dwarfed and assume the form of tall
shrubs. For example, in the Alps, where trees growing near the boundary-line,
beyond which their existence is impossible, are liable to be loaded with heavy masses
of snow, and again, in the valleys annually exposed to avalanches, the Beech grows
in regular thickets. They are, nevertheless, to be looked upon as forests which have

888 PLANT COMMUNITIES AND FLORAS.

been dwarfed by peculiar circumstances to the level of low forest. If the uncon-
genial conditions referred to were to cease, a forest with standard-stems would grow
up on the spot.

IIL. Plains—The dominant plants are perennial and profusely-flowering herbs
and undershrubs of gregarious growth. The form, direction of growth, and mode of
ramification of the aérial herbaceous stems is always conspicuous, and may even be
recognized when the foliage-leaves are of considerable size. Innumerable grades of
this form of plant-community exist between Thistles and Umbellifers, reaching a
height of 2 metres, which flourish on the Steppes, and the undershrubs scarcely
2 centimetres high, which grow on the débris-slopes in high mountain regions. No
sharp line of demarcation can be drawn between them. Nor can any exact distinc-
tion be maintained between those Plains in which annuals and biennials and those
in which perennial growths predominate. It is, however, possible within certain
limits to distinguish between the different types of vegetation under this heading.

IV.—Another type, which may be termed the frondose type, has as its dominant
plants such as have their stems either entirely subterranean, or else rising but
slightly above the ground, whilst from their extremities are developed a crowd of
fronds, branch-like leaves, or leaves with large lamin. The stems are completely
hidden by these leafy structures, so that their form and direction and the nature of
their ramifications are never clearly visible. This type is conspicuously wanting in
flowers. Where flowering-plants also form a constituent part, such plants either
have precocious flowers, which have already passed into the fruiting stage by the
time the mass of foliage has unfolded, and which subsequently disappear without
leaving any trace (e.g. Saaifraga peltata, Tussilago, Petasites), or else their flowers
are so lost amid the innumerable large foliage-leaves that they do not occasion any
material alteration in the general aspect of the plant-community (eg. Funkia,
Nelumbium; see fig. 436, p. 775, and most Aroidew). A special form of this type is
exhibited on the surfaces of stagnant or gently flowing water, where discoid foliage-
leaves rest upon the water and cover the surface completely. Of it there are several
varieties depending on the dimensions of the constituent parts; ¢f., for instance,
Water Lilies and Duckweed.

V. Ribbon-growths.—The dominant plants are social hydrophytes with submerged
stems and foliage-leaves, or with stem-like or foliaceous thalli. Sometimes forms
possessing foliaceous thalli and long, flaccid, ribbon-shaped foliage-leaves predo-
minate, sometimes forms which look like submerged leafy or leafless shrubs, but
which differ from real shrubs in that they are herbaceous throughout. A gregarious
growth of species with thalli or foliage-leaves which are split up into long narrow
segments, or of species whose thalli exhibit a whorled system of ramification may
also be present. Ribbon-growths may be separated into various subdivisions,
according as one or other of these different sorts of plant predominates.

VI. Reeds.—The type is afforded by plants which grow in quantities together
and have herbaceous stems of the kind called haulms and scapes. The stems are
destitute of foliage-leaves (Horse-tails, Rushes, &c.), or else they bear long, narrow

TYPES OF PLANT-COMMUNITIES, 889

leaves. Shoots bearing inconspicuous flowers spring up from the species which
grow in tussocks, whilst the non-tussock-forming, but more continuously crowded
types, develop haulms and scapes bearing an abundance of leaves. The tufted
sedges afford an example of the former, and arundinaceous plants of the latter. A
reed-like vegetation is developed both on marshy and on dry ground; instances of
the latter occur in the Tropics and in Steppe-regions.

VIL. Carpet.—The typical character is given by low, perennial plants, which
form a close mat covering the ground. According as plants with narrow, stiff,
grass-like leaves predominate, or such as form a soft, swelling carpet, two types
may be distinguished; further, according to the nature of its most important
constituents the community may be spoken of as a grass-carpet, herbaceous carpet,
moss-carpet, &c. Carpets may grow either on dry or on marshy ground. Sometimes
they are restricted to the immediate vicinity of springs or form merely a coating to
slabs of rock, but they also spread over wide areas on mountain-slopes and basins.
They belong especially to high mountains and to the Arctic regions.

VII. Incrustment—The dominant species are Thallophytes, which become
rigid and brittle when dry or as a consequence of being incrusted with lime. The
aggregations of these plants either form solid banks and reefs or else spread in the
form of a loose covering over the earth, or they appear as incrustations on rock,
earth, or sand. They develop both in the air and under water.

IX. Felts—The dominant species are plants possessing thalli composed of
delicate filaments which are more or less entangled together. They may grow in
water either in a flocculent form or in coherent felted masses, and they also appear
as a thin coating to stones or earth, in which form their characteristic colours render
them visible from afar.

The names applied to the above nine classes or types of plant-communities are
purposely devoid of reference to the particular alliances, families, or genera
concerned in the formation of the communities, because the origin of the latter
has nothing to do with the existence of any affinity amongst their constituent
plants. Nor has it been possible to take into account the nature of the habitats or
the situation of the zones and regions of the earth’s surface where the communities
grow. This is not the case, however, when we come to name the separate com-
munities which belong to the above classes. For this purpose the use of a name
which refers to the habitat, zone, or region where the particular community
flourishes, or to the ruling species, genera, or families of which it is composed, is
not only inevitable but actually desirable. The most convenient system of nomen-
clature to adopt here is that which has proved the best in all other descriptive
sciences. In accordance therewith each plant-community is designated by two
names, one denoting the class to which the community belongs and the other
indicating its special characteristics.

In the present state of our knowledge it is impossible to name even approxi-
mately the plant-communities which are formed by the aggregation in various
ways of some or other of the many thousands of species inhabiting the earth. I

890 PLANT COMMUNITIES AND FLORAS.

SESS

Fig. 481.—Bamboo Forest in Ceylon (from nature by von K6nigsbrunn). t

TYPES OF PLANT-COMMUNITIES.

891

Fig. 482 —Mangrove Forest in India (from nature by von Ransonnet).

892 PLANT COMMUNITIES AND FLORAS.

will therefore only make a few observations on the subject, and draw attention to
the most striking cases of plant-communities.

The greatest interest naturally attaches to forests which impress the observer
by their size, and it is easy to understand why these have always been chosen for
the most thorough investigation and description. As regards the species which aré
either the only constituents of the community, or at any rate its ruling members,
we must first distinguish forests of deciduous Conifers and those of evergreen
Conifers. A Larch forest (see fig. 354, p. 483) may be taken as an example of the
former. Of the evergreen variety there is an extremely large number, owing to the
fact that most true Conifers grow in dense forests. A forest of Spruce Firs is
represented on p. 415, vol. i, a forest of Silver Firs on p. 717, vol. i, of Scotch Pines
on p. 723, vol. ii, and of Arolla Pines on p. 724, vol. ii. Forests composed of
Angiosperms are likewise differentiated into deciduous and evergreen. Amongst
deciduous forests of this kind the Beech-woods (see p. 761), Birch-woods (see p. 721,
vol. i.), and Oak forests (see vol. i. p. 716, fig. 173) of the North Temperate Zone
are especially noticeable on account of the characteristic aspect exhibited in
each case. Angiospermous evergreen forests manifest their greatest variety in
tropical and sub-tropical regions. To the Tropics belong also a number of other
special kinds of forest, such as those composed of Euphorbias, Casuarinas, Bamboos
(see vol. i. p. 718, fig. 172), of Mangroves (see vol. i. p. 605, fig. 143, and p. 759,
fig. 187), and of Palms (see vol. i. Plate VIII. opposite p. 712), respectively. Drawings
from nature in the Tropics represénting Bamboos and Mangroves are also given in
figs. 481 and 482.

Scrubs, which are, so to speak, repetitions of woods or forests in little, may be
similarly divided into groups. We distinguish between those in which the shrubs
and semi-shrubs, which are predominant or in exclusive possession, are leafless and
those where the shrubs are provided with foliage. Amongst the social plants of the
first group switch-plants and certain cactiform plants play a prominent part (see
vol. i. p. 331, fig. 80, and Plate IV. p. 446). The social plants of the second group are
either evergreen or deciduous. The former are furnished with acicular or squami-
form leaves which are appressed to the branches (shrubby Conifers and Heaths), or
else are clothed with flat, expanded leaves. The case of Alpine Roses (see Plate X.)
will serve as an example of the second variety. Amongst deciduous shrubs and semi-
shrubs which grow sociably and form extensive scrubs we may mention Tamarisks,
Spirzas, Roses, Dwarf-Almonds, Dwarf-Birches, Dwarf-Willows, Proteaces, Labiate,
Broom, and Mimosas. ,

As regards plains we must first distinguish those where the predominating
perennial plants have no foliage-leaves, but are furnished instead with green, fusi-
form shoots and branches of a foliaceous nature (e.g. Salicornia). Of leafy plants
which occur as predominant members of plains we may mention Umbellifers,
Thistles (see vol. i. p. 486, fig. 115), Agaves and Pine-apples (see vol. i. p. 657,
fig. 153), and the Asphodel (see fig. 413, p. 729), as the most striking examples.
The rest of the social suffrutices may be placed in three groups. The species

TYPES OF PLANT-COMMUNITIES, 893

belonging to the first group, to which belong in particular many Composites,
Caryophyllaces, Chenopodiacen, Papilionacers, and Cruciferss, are multifariously
branched from the very base (e.g. Artemisia, Gypsophila, Salsola, Melilotus, Crambe);
the species of the second group have upright stems which are unbranched up to
the region of the flowers and bear entire leaves (e.g. many species of Verbascum,
Epilobium, Enothera, Euphorbia), and the species of the third group possess
erect stems which have few branches, or none at all, but bear variously lobed and
compound leaves (e.g. Glycyrrhiza, Eupatorium, Tanacetwm, Sambucus Ebulus).

As regards the fourth or frondose type (cf. p. 888), we have already indicated
certain varieties. In describing the different communities of this kind special
emphasis must be laid also on the circumstance of the green laminz being entire, as
in Petasites, Tussilago, Nelumbium, Asarum, Scolopendriwm, and Saxifraga peltata,
or divided and incised, as in most Ferns, several Aroids, and a few Hellebores.
We must also take into account whether the fronds or foliage-leaves are deciduous
or evergreen, as in Hedera and Helleborus niger.

Ribbon-plants occur in great variety in both flowing and stagnant waters, be
they fresh, brackish, or salt. The general aspect of any particular aggregate of these
ribbon-like forms varies according to the area and shape of the foliage or thallus of
the species concerned, and particularly according to whether the stems or the stem-
like parts of the thallus are lax or packed close together so as to form a dense,
pulpy matrix. The most conspicuous examples of social species are Myriophyllum
with pectinate leaves, the Pond-weeds (Potamogeton) and Zannichellias with filiform
leaves, the Pond-weeds with broad, translucent leaves (see vol. i. p. 551, fig. 136),
the Grass-wracks (Zostera), Vallisneria (see vol. i. p. 667, fig. 155), and Cymodocea,
also a few of the Mosses (e.g. Fontinalis), various species of Fucus, Laminaria (see
vol. i. p. 588, fig. 139), Sargasswm, Macrocystis, and Cystosira amongst Brown
Seaweeds, species of the genera Ceramium, Callithamnium, Polysiphonia, and
Lemanea amongst Floridee, the species of Bryopsis and Cawlerpa amongst the
Siphonez, and the several species of Chara and Nitella amongst Stoneworts.

The points whereon the classification of Reeds is based have been already
indicated on p. 888. A number of distinct forms may be distinguished according
as particular species of Horse-tail, Sedge, Rush, Restiacez, Scirpus, Calamagrostis,
&e., prevail. The drawing of a Papyrus-swamp on p. 747 may be taken as
typical of this class of vegetation. In the North Temperate Zone, of those which
grow on dry ground the most prevalent species are those of the genus Calama-
grostis. A great many Reeds occur in the Tropics and in the Steppe regions of both
the Old and the New World, especially in the pampas, llanos, &c.

The plants which constitute the dominant members of carpet include both
Phanerogams and Cryptogams. Of the former the most important are the inter-
weaving and tussock-forming Grasses, Sedges, and Rushes, the interlacing, grass-
leaved Caryophyllacee (e.g. Alsine Rosani, Cherleria sedoides, Silene acaules), the
species of Houseleek (Sempervivum) which form rosettes, the Saxifrages of the
Aizoon group, the loosely-woven delicate Saxifrages which grow near springs, and

894, PLANT COMMUNITIES AND FLORAS.

lastly, Montias. Of the Cryptogams almost all are Mosses, the chief species being
the Sphagnums, Polytrichums, the species of Dicranwm and Gymnostomum which
grow in dense aggregates, and the Hypnums which cling together in loose mesh-
work (eg. Hypnum Schreberi, Hylocomiwm splendens, and Hylocomiuwm tri-
quetrum).

Only Lichens, Floridex, and a few Stoneworts take part in the formation of
incrustments. Extreme variety is exhibited by Lichens which combine to form
crusts closely appressed to the substratum. The chief dominant plants are various
species of Acarospora, Amphiloma, Lecanora, Lecidella, Pertusaria, and Verru-
caria. The best-known and most widely-distributed incrustment is that which is
formed by Lecidea geographica or Rhizocarpon geographicwm, and imparts a
characteristic colour to the blocks of stone on slaty mountains. A looser type of
incrustment is composed of various fruticose Lichens, principally of Cladonias and
Cetrarias, and are most striking in high mountains and in the Arctic tundra. A
less important form is one composed of submerged Characez and Floridez incrusted
with lime, e.g. by species of Corallina. The lime-incrusted species of Lithothamniwm
and Lithophyllwm which combine to form solid bank-like incrustations known as
nullipore-banks only occur in the sea.

Felts are formed by filamentous Alge. The dominant plants are Scytonemaces,
Conjugate, Ulotrichacess, (Edogoniacer, Vaucheriaces, anda few others. The
Conjugates, such as the various species of the genus Spirogyra, fill stagnant ponds
with their green filaments; several of the Vaucheriacese grow in closely felted masses
in water-courses or on damp earth, and several Scytonemacexw and Confervoides
weave themselves into thin mantles over stones. Felts are but seldom of very con-
Spicuous appearance. The best known is the thin felt formed by Trentepohlia
Lolithus, to which is due the red coloration of blocks of stone (“ Violet-stone”) seen
in mountain regions.

It is only in rare cases that a plant-community is composed of a single species
alone. For the most part two, three, or even more species of similar aspect are
jointly predominant. At the same time it may happen that at one spot one species,
at another spot another species is kept in check without any material alteration
being thereby incurred in the general appearance of the particular community.
Thus, for instance, the slopes of the schistose mountains of the Central Alps are
clothed with carpets in which Carex curvula, Juncus trifidus, and Oreochloa
disticha are dominant species. Here and there these three species share equally
in the composition of the carpet, but in many places one is paramount, whilst the
others sink into the background, so as to be scarcely noticeable at first sight. No
further explanation is requisite to show that in such cases the community must not
be named after one only of the dominant species.

As regards the subordinate species of a community it would be a great mistake
to suppose that their occurrence is subject to no sort of rule. Though they seldom
have any striking influence on the tout ensemble of the community their importance
in it must not be under-estimated. Many of them are so constantly associated with

PLANT COMMUNITIES, 895

certain gregarious species that, where a plant of the one kind occurs, the presence of
its companion species of the other kind may be inferred with certainty, and obviously
due regard must be paid to such constant companions in any description of par-
ticular communities. A further circumstance which must not be overlooked is that
up to a certain point the subordinate species may replace one another. Thus, for
instance, that variety of carpet in which the Mat-grass (Nardus stricta) forms
the dominant species, includes as subordinate species both in the Alps and the
Carpathians Homogyne alpina, Hieracium alpinum, Campanula Scheuchzeri, &e.
Certain other subordinate species, e.g. Potentilla awrea, Hypocheris Helvetica and
Campanula barbata, which are almost invariably present in the community in
question when it grows in the Alps, are, however, replaced in the Eastern Carpathians
by Potentilla chrysocraspeda, Scorzonera rosea, and Campanula abietina.

Special attention must be drawn to the fact that species which are gregarious in
one plant-community occur as a mere sprinkling in another. When this observation
is first made in Nature it is apt to lead one to suppose that it is a vain task to
attempt to arrange the different communities in groups, and to define and describe
each separate kind. But more careful study soon convinces one that the pheno-
menon in question, far from interfering with the scientific treatment of the subject,
actually assists it, and that the history of plant-communities is elucidated thereby.
It has been repeatedly remarked that mud newly deposited by water, exposed soil,
and naked rock do not forthwith deck themselves in their permanent mantle of
vegetation, but that first of all small Algz, Lichens, Mosses, and various annual
Phanerogams establish themselves and prepare the way in the course of time for
other plants. This preparation, which was described in vol. i. pp. 257-268, consists
not only in mechanical changes in the ground, but also in the admixture of humus
derived from the parts of the first settlers which die off. The only species which
take possession of ground so modified are such as differ entirely from the first
colonists, and, curious to relate, the latter are gradually ousted by the new arrivals
and driven from the field. But the second settlement has no permanence either.
The quantity of humus arising from the death of plants increases from year to year,
the soil becomes too rich for the plants in possession, and the process of eviction is
now undergone by them at the hands of fresh species, which thrive on the rich soil,
and gradually possess themselves of it. At least three successive series of settlers
may thu: be traced on every spot, and not infrequently the number is four or five.
Now, if each of these groups corresponds to a particular community, which is as a
matter of fact the case, the phenomenon described must produce the same impression
as though the communities became transformed into one another in course of time. It
is therefore necessary to recognize the existence of the incipient and decadent stages
as well as that of predominance. In the incipient stage relics of the community
which previously occupied the same spot are still to be found, and in the stage of
decadence the first pioneers of the community that is to succeed make their appear-
ance. When, for example, a carpet is invaded here and there by individual plants
belonging to species indicative of communities which pertain to some other type,

896 PLANT COMMUNITIES AND FLORAS.

such as scrub or plain, the occurrence does not in the least confuse the definition and
description of the carpet. It only shows that for purposes of determination and
description, whilst attending primarily to the stage of the community when develop-
ment has reached its zenith, we must also take into account in each case the stages
of incipience and decadence, and the relations to other communities.

Wherever the configuration and composition of the ground favour the formation
of various kinds of habitat within narrow limits of space, there the particular plant-
communities which correspond to those habitats develop in great variety close
together. The boundary-lines of adjacent communities are disposed in a multitude
of different ways in such cases. In lowlands where gentle hills alternate with
shallow depressions, and where from sand one passes to clay, and thence, perhaps, to
ground covered with saline efflorescence, the communities are not infrequently pieced
together like the components of a mosaic. In other places those which cover a small
area are interspersed like islands in the midst of the more extensive communities;
and, again, in other cases the different areas are in the form of contiguous strips
and zones. The last mode of distribution occurs chiefly along the margins of still
or running water, and is explained by the uniform diminution of moisture in the
ground as the distance from the water's edge increases, and in the case of still water
also by the tendency of plants to advance from the margins towards the middle of
the expanse of water where they grow, or, in other words, from the continuous trans-
formation of the ribbon types which flourish in water into reeds, of reeds into plains,
and of plains into carpets or into forests.

It very often happens that two or more plant-communities are intermingled, and
that the whole exhibits a kind of stratification. A pine forest may exist by itself,
that is to say, it may include nothing but dominant pines with, perhaps, a sprinkling
of a few other kinds of tree, and the ground may be bare except for a bed of dry
fallen needles. On the other hand, a carpet may have developed on the forest floor,
whilst, in addition, a Bilberry scrub, a low scrub of Calluna vulgaris or Erica
carnea, and a high scrub of Juniper may have obtained a footing, all of which
communities are capable of existing independently without the shelter of the pines,
and are often met with thus alone. But although the presence of the one com-
munity is not indispensable to the existence of the other, the fact of their occurring
together shows that no injury is suffered on either side in consequence of the com-
panionship, and it is much more likely that communities growing on the same
ground are mutually helpful and protective. In many cases there is no doubt of
this, as, for example, when a community of tall plants develops on soil previously
prepared by a community of low plants without completely ousting them. We
gather, then, that the conjunction of several communities is by no means fortuitous,
that the association is always between certain particular communities, and that even
here we find strict orderliness and subjection to definite laws.

Unions of communities formed in the manner above described have been termed
plant-formations, probably from analogy with the combinations of strata of earth
and stone which geologists call formations. The selection of this name is not quite

PLANT-FORMATIONS, 897

fortunate, but having been once introduced into the science, it must remain, and it
is only necessary to point out that the communities united in a formation do not
always exhibit any obvious stratification. Thus, for instance, in many tropical
forests (see fig. 420, p. 741) communities are interpolated which belong to the most.
widely different types, and exhibit all possible grades in respect of the height to
which their component plants grow. These communities occupy sometimes only a
restricted area, sometimes a considerable expanse either down on the ground or
midway between the ground and the tops of the trees; and, moreover, in all such
formations there is always a sprinkling of climbing-plants and epiphytes, which
make it quite impossible to discover distinct strata. In many other cases, it is true,
the communities constituting a formation are in obvious strata. If we may compare
the plant-formation to a building, the communities may be said to form the stories
rising one above the other. Sometimes only two communities are superimposed on.
one another, sometimes it is possible to distinguish three or more strata or stories.
There are formations in which each story belongs to a different class of community,
but others exist also where two or three of the stories are of the same class, as, for
instance, where several scrubs rise one above another, or where two forests are
united, so that the crown of one species of tree forms an upper tier, and that of
another species a lower tier.

The names of the different plant-formations should be chosen with regard to the
community which forms the roof of the entire edifice of plants in each case, and
which, therefore, projects above, and, in a sense, prevails over all the other com-
munities.

At the beginning of this chapter stress was laid on the fact that every region
receives a characteristic impress from the nature of the plant-communities inhabiting
it, and that a knowledge of the latter is consequently of great importance in descrip-
tive geography. The remark has also been made more than once that the particular
conditions of soil and climate in a locality find expression in plant-communities, as.
it must be presumed that the species characteristic of each community can only grow
in masses at places where the composition of the soil and the conditions of illumina-
tion, temperature, and humidity are in harmony with the specific organization as a
whole. But if the local conditions of the ground and climate are reflected in the
plant-communities, it is equally the case that the distribution of the plant-communi-
ties and formations constitutes an important and perhaps the only available basis
for a division of the earth into natural floral areas. We proceed on the principle
that every district possessing a series of plant-communities which are peculiar to
itself is to be treated as a floral area, and that a limit to such area occurs at every
place where the characteristic communities of a particular floral area are threatened
with destruction, and, therefore, encounter the natural boundary of their range,
where other communities better adapted to the altered external conditions make
their appearance, and where there is consequently a change in the aspect of the
whole landscape. This also supplies the scheme for a scientific geography of plants.

Unfortunately we are still far from possessing any such science. We have only a
Vor. IL 107

898 PLANT COMMUNITIES AND FLORAS,

scanty knowledge of the plant-communities of Central and Northern Europe, and in
many extensive tracts as good as nothing is known concerning the most important
of all the data required for a demarcation of floral areas. There is nothing for it,
therefore, for the present but to grope along with the help of the little that has been
ascertained, and in the case of many districts to retain the demarcations laid down
by earlier investigators, notwithstanding the fact that they are based upon altogether
different foundations.

According to this system, the various Floras may be roughly distinguished as
follows:—

1. Arctic Flora. The northern parts of Europe, Asia, and North America, extending south-
wards about as far as to the Arctic Circle.
2. Baltic Flora. Scandinavia, Great Britain, North-German Lowlands, Western Russia encroach-
ing to the south on the Floras of the Mediterranean and Black Sea.
3. Flora of the Black Sea. South-eastern Europe, Asia Minor with the exception of its southern
and western shores, the Caucasus, Kurdestan, Persia: environs of the Caspian Sea.
4, Mediterranean Flora. Shores of the Mediterranean: Southern Europe, the western and
southern shores of Asia Minor. Coasts of Syria, Egypt, Tunis, and Algiers.
5. Atlantic Flora. Azores, Canary Islands, western shores of the Spanish Peninsula, Morocco.
6. Siberian Flora. The plain extending from the river Obi and its sources to the Stanovoi
Mountains. ;
. Kamschatkan Flora. North-east Asia as far south as the region of the Amur River.
. Amur Flora. Amur district, Manchuria.
. Chinese Flora. China, Japan, extending nearly as far south as the Tropic of Cancer.
10. Flora of Central Asia. Mongolia, Thibet, bounded to the west by the Steppe-region of the
Sea of Aral, and to the south by the Hindu Kush and the Himalaya.
11. Flora of South Arabia and Mesopotamia. Northern shores of Somali, South Arabia,
Mesopotamia; shores of the Persian Gulf.
12. Sahara Flora. The Sahara to about 15° N. Lat., Northern Arabia.
13. Soudanese Flora. Bounded on the north by the Sahara, on the south by 10° N. Lat., to the
east by the mountainous region of Abyssinia.
14, Flora of Guinea. From 10° N. Lat. to 10° S. Lat., eastwards to 35° E. Long.
15. Zambesi Flora. From 10° S. Lat. to the Orange River on the south, and bounded to the
east by the Drakenberg Mountains and Lake Nyassa,
16. Abyssinian Flora. Abyssinia and the mountains adjoining it on the south.
17. East African Flora. From the shores of the Indian Ocean to the East African Mountains,
northwards as far as 8° N. Lat.
18. The Cape Flora. The south-western part of the Cape, bounded to the north by the Great
Karroo Desert.
19. Madagascan Flora. Madagascar.
20. Indian Flora. Bounded to the west by the Indus, to the north by the Himalaya and the
Yunnan mountains, and extending eastward as far as the Straits of Lomboc and Macassar.
21. Pacific Flora. Pacific Islands from the Moluccas to the Marquesas Islands on the one hand,
and from the Sandwich Islands to New Zealand on the other.
22. Tasmanian Flora. Victoria, Tasmania, New South Wales, and adjoining regions,
23. Australian Flora, Interior and Western Australia.
24, Canadian Flora. Bounded to the north by the Arctic Flora, and reaching westward as far
as the Rocky Mountains, and southward as far as the North American Lakes,
25. Columbian Flora. Bounded on the north by the Arctic Flora, on the east by the Rocky
Mountains, on the south by 50° N. Lat.
26. Mississippi Flora. Extending northward to the Lake region, southward to Florida, exclusive
of the southern third of that Peninsula, and bounded to the west by 95° W. Long.

oon

THE EXTINCTION OF SPECIES, 899

27. Missouri Flora. Region of the Missouri River and of the high land between the Rocky
Mountains and the Cascade Mountains,

28. Flora of the Pacific Slope. Coast region west of the Cascade Mountains, California.
29. Texas Flora. Arizona, Texas, North Mexico,

30. Mexican Flora. Mexico as far as N icaragua,

31. Antilles Flora. The Antilles and the Bahamas, southern extremity of Florida.

32. Brazilian Flora. Bounded to the west by the Andes from the Gulf of Guayaquil to Tucuman,
extending southward to 30° S. Lat.

33. South American Flora. Coast land west of the Andes and the part of South America be-
tween 30° and 50° S. Lat.

34, Magellan Flora. The extremity of S. America from 50° 8. Lat., excluding the high mountains.

35. ee Flora, Antarctic Islands, high mountains of the southern extremity of South
merica.

In this outline only a passing reference has been made to the Floras which
at present occupy the higher regions of mountain chains, and which are restricted
to comparatively small areas. Yet there is often far more difference between these
and the Floras of the lower parts of the mountains and of the adjacent plains than
there is between Floras which exist side by side in the lowlands, and are usually
scattered over wide areas. Thus, for example, the Flora of the high mountains
of Central Europe, commonly known as the Alpine Flora, differs so utterly from
the Baltic Flora developed to the north of the Alps, and from the Mediterranean
Flora flourishing to the south on the shores of the Mediterranean Sea, that it could
not be classed either with the one or with the other. The same phenomenon is
observed in other regions where lofty mountains occur, and, probably in addition
to the thirty-five Floras above mentioned, as many more high-mountain Floras
might be distinguished. The importance of these mountain Floras in relation to
the formation of the Floras of the plains and to the general history of the plant-
world will be set forth in the next section.

5. THE EXTINCTION OF SPECIES.

In the portion of this work which dealt with the origin of species, the view was
taken that the new species which make their appearance in the course of ages are
the products of cross-breeding between previously existent species. Valuable
support is given to this opinion by facts relating to such genera as are repre-
sented in one district by a large number of species, and in another by a single
species only. In many cases the wealth of forms comprised by a genus is pro-
digious. It.is no easy matter to bring the numerous species of such a genus under
review in a single series, because they are connected not only lineally, but also
collaterally amongst themselves in all sorts of ways by intermediate forms. Within
these generic spheres new forms continue to spring up in our time, and these are
proved to be the results of crossings. For example, the multiplicity of forms
included in the Bramble-genus (Rubus) is extremely great in Central Europe.

900 THE EXTINCTION OF SPECIES.

Botanists of the old school supposed the reason of this to be that the species of
Rubus vary from some unknown cause—presumably from an intrinsic tendency in
themselves. At the present day no intelligent observer doubts that many of the
plants thus set down as the results of mere spontaneous variation are species which
arose by inter-crossing in comparatively early times. Such inter-crossing was
rendered possible by the fact that in the course of those displacements and altera-
tions affecting floras, to which the present distribution of plants must be attributed,
several species of Rubus, which had survived from previous periods, met and settled
down together in Central Europe. On the coasts of Dalmatia and Greece, where
only a single species, viz. Rubus ulmifolius, Schott (=R. amenus, Portenschlag),
established itself when the changes in question took place, there was no possibility
of any multiplication of forms. From that solitary species sprang descendants
which never changed; in other words, the specific marks of Rubus ulmifolius
remained permanent in the above-mentioned parts of the Mediterranean floral area.
The idea of the old school of Botanists was that this particular species of Rubus
had no inclination to evolve new species; or, to use the more erudite but still less
intelligible mode of expression, it was destitute of any tendency towards differentia-
tion. The proper explanation of the fact is, however, much simpler and more
natural. In the region where this particular species of Rubus is settled, there is no
possibility of new species of that genus arising by means of inter-crossing. Perhaps
some future displacements of floras will bring Rubus ulmifolius into proximity
with other species of Bramble, and in that case it is sure to take part once more in
the generation of new species. If, on the other hand, some event should cause
the extermination of the entire Bramble-flora in the adjacent districts, and Rubus
ulmifolius should remain isolated, no new species will spring from it any more
than hitherto. A completely isolated species may continue to reproduce and
multiply sexually and asexually for centuries without exhibiting any alteration,
provided that the conditions of climate and soil are congenial to it, but it cannot
take any part in the production of new species. If at length destruction befall such
a species—a by no means impossible contingency, as one change of climate succeeds
another, and causes fresh displacements of the limits of plant distribution—the
event would connote the extinction of the whole genus of which this species was
the sole surviving representative.

The result of comparative researches has been to show that the extinction of
single species frequently occurs, whereas such groups of species as Botanists designate
by the name of genera rarely die out. By far the greater proportion of the plants
whose remains have been preserved from former periods in a fossil condition
belong to genera which are represented by plants still living at the present day;
only many of the extant representatives differ specifically from those which existed
long ago. We conclude that the living types replace extinct ones and have entered
upon their parts in life. It is also worthy of note that the fossil remains are often

found at entirely different places from those inhabited by their nearest relatives in
modern times.

THE EXTINCTION OF SPECIES, 901

The most striking examples of genera that have become extinct are afforded by
the alliances to which the Club-moss and the Horse-tail respectively belong (see pp.
713 and 716). Those genera most exposed to the danger of extinction are such
as are only represented by a single species (termed monotypic genera). This risk
is intensified if the species in question only occurs in one district, as is the case,
for instance, with Welwitschia. The genus Rhodothamnus of which only one
species, 2. Chamocistus, lives at the present day, and the genus Azalea which is, so
far as we know, represented by the species A. procumbens (Loiselewria procumbens)
alone should, on the other hand, have a better chance of escaping extinction. For
the area of distribution of the former is broken into two sub-areas by the broad
stretch of land reaching from the Eastern Alps to the Altai Mountains, whilst the
Azalea grows not only on the high mountains of Central and Southern Europe but
also in the Arctic regions, leaving a great space between the two areas uninhabited
by its kind. Thus, presumably, even if such a species were to vanish entirely from
one of its sub-areas of distribution in consequence of changes in climatic conditions
it would still be represented by individuals growing at some spot which, being
remote from that sub-area, would in all probability not have been affected by the
alterations in question.

The number of species that have died out is extremely large. Every group of
species which comprises both living and fossil members affords instructive examples
in this connection. It is assumed that of species now living the endemic kinds have
their existence most seriously menaced, or, in other words, are exposed to the most
speedy extinction. If the restricted areas of the South-eastern Alps, where Wul-
jena Carinthiaca, the most famous of the endemic species, is native, were to
undergo a change of climate which no longer permitted the propagation of that
species either by sexual or asexual methods, and at the same time rendered its
migration impossible, it would be only a matter of time before Wulfenia Carinthiaca
disappeared completely from the face of the earth. The genus Wulfenia would not,
it is true, thereby become extinct, for a second species named Wulfenia Amherstia
occurs in the Himalaya. But as this species, too, is endemic it might easily be
overtaken by the same fate, and then the entire genus would have died out. It is,
however, conceivable that the change of climate supposed to affect the South-eastern
Alps, instead of causing the extinction of Wulfenia Carinthiaca, might result in the
expansion of its area of distribution, and that no such hindrances to its migration
as at present prevail should exist. The two species now inhabiting such widely
remote districts might then conceivably come together and cross with one another,
with the result that new species would be produced in the genus Wulfenia. It will
be seen from these examples that one cannot be too cautious in dealing with assump-
tions concerning the future destinies of species. Many endemic species are probably
doomed to extinction in the near future; but it is also not impossible that they may
instead be called upon to play an important part in days to come.

An account has already been given (pp. 590, 592) of the manner in which
nature affords compensation for the extinction of species, and how new species, the

902 THE EXTINCTION OF SPECIES.

products of crossing, take the place of the parent-stocks, so that the only remark that
need be added here is that when such substitution is observed in the case of plants
belonging to successive geological periods, it seemed as though a gradual re-casting
or moulding of the species had taken place, and was regarded as a phenomenon
determined by the direct effects of variations of climate until the time when the
great importance of crossing in relation to the genesis of new species began to be
recognized.

The partial extinction of a species, i.e. its disappearance from particular parts of
its area of distribution, must be distinguished from complete extinction. Of the
numerous instances of partial extinction within our knowledge some have been due
to intentional or unintentional extermination by mankind, but the majority are cases
where purely local extinction has resulted from natural causes independently of
human influence. Reference has repeatedly been made in these pages to cases of
plants which grow in the midst of now reigning floras and yet do not belong to
them, and they have been likened to outposts left behind by former occupants of
the soil, being apparently the remains of floras which formerly flourished on the
areas in question, but which have been turned out and forced to take refuge in
neighbouring regions. If their displacement were due to climatic vicissitudes it is
conceivable that separate species or even entire communities may have been left
behind here and there in especially favourable, though possibly very restricted
habitats, and such isolated spots then seem as though they had been wrested from
the main area of distribution which stretches over a wide expanse of country in the
vicinity. Interesting examples of this are afforded by several species which are
confined to isolated habitats in Carniola, of which the “Kénigsblume” (Daphne
Blagayana) may be selected as a type. This plant grows on the slopes of some,
mountains in the neighbourhood of Laibach. Before the flora of the Balkan Penin-
sula had been accurately explored it was believed that this species of Daphne
had no other habitat than that on the mountains above mentioned. More recent
botanical researches have, however, revealed the fact that the main area of distribu-
tion of Daphne Blagayana is really in the Balkan Peninsula, in Bosnia and Servia,
and that the habitat in Carniola is to that area as an island to the mainland.
When one sees by what a small number of individuals, amounting to some thousands
only, this curious plant is represented in Carniola, and how rare it is for even these
to bring fruits to maturity owing to the fact that autogamy is impeded and that
the supply of insect-visitors is insufficient, there is no escape from the conviction
that a series of very severe winters would be enough to cause its complete extermi-
nation in this district. Under such circumstances its existence in the main area of
distribution in the Balkan Peninsula might not be in any way imperilled, for it is
not likely that the particular causes to which the extinction of the species in the
small area in Carniola would be due would operate in all the habitats in the larger
area, which is hundreds of kilometres away.

That such phenomena as have here been suggested as possible and even probable
in the case of Daphne Blagayana do actually happen is evidenced by the plant-

THE EXTINCTION OF SPECIES, 903

species which in one district form a considerable part of the flora in possession at
the present day, whilst in another floral area they are only found in the fossil state
and under conditions which leave no doubt that they formerly lived there, but have
long died out. Rhododendron Ponticum, for example, is an important constituent
of the flora which now flourishes in the neighbourhood of the Black Sea, and is also
found far to the west in an unrestricted area in the South of Spain at a great
distance from the main area of distribution. It is encountered in the fossil state on
the southern slopes of the Solstein chain in Tyrol in the upper strata of the so-called
Hottinger Breccia, Thus this plant must have ranged formerly through Southern
and Central Europe to 47° N. Lat. In the South of Spain it has survived on an
isolated spot, whilst in the Northern Dolomites it has died out. A similar instance
is offered by the case of several Juglandacez which form part of the woods of North
America at the present day, and are only found as fossils in Europe.

The results of researches into the history of the separate species constitute the
foundation for a history of the entire plant-world. Formerly the discovery of fossil-
remains was looked upon as the most important means of eliciting that history, but
now the distribution of living plants is taken into account, and the significance of
such circumstances as the presence of endemic species and of species isolated in the
midst of a foreign flora is fully recognized. A study of endemic species and of
outlying sub-areas of distribution yields in particular most valuable information
concerning the conditions which prevailed in the earliest periods of the earth’s
history. The most noteworthy inference made in this connection is that over a
great part of central Hurope since the last ice-age a flora was evolved which was
only capable of existing under the influence of a continental climate of far greater
warmth than now prevails. For instance, plants whose main areas of distribution
at the present day are in the steppes of Southern Russia, in the Crimea, and in the
valleys of the Caucasus are found growing, sometimes alone sometimes in com-
munities, in Central Europe, in the region of the Baltic Flora, on warm, sunny
mountain-slopes, and in sequestered glens far from the modern lines of traffic, and
under circumstances which exclude all possibility of an immigration having taken
place in recent times. Such exceptional habitats of the plants in question occur on
hot, sombre rocks of serpentine in Lower Austria, on terraces of loess and mountains
of schist, situated on the eastern border of the Bohmer Wald and the Mahrische
Gebirge, in the interior of Bohemia and westwards on scattered spots as far as the
Harz Mountains, and, again, in the region of the Northern and Central Alps, from
the Wiener Becken to the Lake of Constance, as, for example, far away in the highest
parts of the valleys of the Adige and the Inn. These plants may be for the most part
described as Steppe-plants, and if, as can no longer be doubted, they are the remains
of a flora which once ranged in Central Europe as far as the Harz Mountains, we
may conclude that just before the establishment of the present climatic conditions
which suit the Baltic Flora, a Steppe-climate prevailed over the area referred to,
and the summer was hot and dry. There is good ground for supposing that the
various animals belonging to the Steppe-fauna (Steppe-antelope, Steppe-marmot,

904 THE EXTINCTION OF SPECIES,

&c., of. p. 462) which have been discovered in Central Germany are relics of this
period, that they lived with the Steppe-plants and withdrew eastward at the same
time in consequence of the change of climate. It is difficult to say when these
changes took place in Central Europe, but this much is certain, that the Steppe-
climate prevailed for an exceedingly long time, that the alteration of that climate
into the kind which now prevails took place quite gradually, and that accordingly
the migration of the Steppe-flora and fauna into the region now occupied by them
was performed very slowly.

As the very thing which is injurious to the members of one flora is usually
beneficial to those of a neighbouring flora the migrations of plants really take
the form of displacements of the boundaries of distribution. No sooner do the
species of one flora withdraw to escape a climate that has become unsuitable to them
than their place is taken by those members of the neighbouring flora which are
adapted to the new climate. In the case above referred to, an immigration of such
members of the Baltic flora as prefer a comparatively cool, moist summer would
inevitably take place synchronously with the retreat of the Steppe-plants. As
regards the situation of the previous home of these Baltic plants there can be no
doubt. They came from adjacent regions where the climatic conditions congenial to
them already existed, that is to say, from parts then forming the coast and from
those mountains which had not been ascended by the Steppe-flora. In advancing
inland from the coast and descending from the mountains these plants were only
in a measure retracing their steps to places where they formerly occupied the
ground, and from which they had been ousted by the Steppe-plants. In other
words, before the reign of the Steppe-flora of the Black Sea was established in the
valleys and lowlands of Central Europe another flora lived there which closely
resembled that which we now call the Baltic flora. No approximate estimate can
be given of the length of time, previous to the immigration of Steppe-plants, during
which the Baltic flora was in possession of the tract of country thus destined to fall
a second time under its dominion; but it has been established beyond question that
it was not as yet upon the scene at the period of the greatest prevalence of glaciers
in Central Europe, and that its first immigration cannot have taken place until after
the retreat of the large glaciers.

At the epoch when glaciers attained their maximum dimensions the places now
covered by the forests of Pines and Firs, which are so characteristic of the Baltic
flora, and by vast scrubs of heaths and broom, were occupied by low Alpine plants
which may for the sake of brevity be spoken of collectively as an Alpine Flora.
Formerly botanists were of opinion that this wonderful flora spread southwards like
a flowing stream from the Arctic Regions at the epoch in question. This view is not,
however, in harmony with more recent discoveries, It was based on the erroneous
assumption that the flora of the Arctic Regions was the same as that of the alpine
regions of Central and Southern Europe. When we compare the Arctic and the
Alpine floras merely by means of their records in books and herbaria, it does indeed
look as if the closest relationship existed between the two: for a not inconsiderable

ALPINE AND ARCTIC FLORAS, 905

number of species belong to both floras, and are only lacking at the present day in
the broad tract interposed between the Alps and the Arctic Regions. But of these
species common to both floras the majority are distinguished in the Alps by their
rarity, and only grow on particular spots here and there on black earth or peat, or
close to cold springs. Many must be the botanists who have rambled year after
year over the Alps collecting flowers without ever coming across such species as
Saxifraga cernua, Betula nana, Juncus arcticus, and Juncus castaneus, which are
common in arctic areas of vegetation but very rare in the Alps, though they may
have climbed all the summits high and low, and searched the most sequestered
valleys, and, moreover, may possess a thorough knowledge of Alpine vegetation.
Similarly, when a Botanist, who has acquired on the spot an accurate knowledge of the
Arctic Flora, pays his first visit to the Alps an entirely new world meets his gaze. Not
only is the number of species indigenous to alpine regions much larger than that
found in the extreme north, but the two floras differ widely in their composition.
The very species which are of most common occurrence in the Alps, and which con-
stitute the ground-work of the communities characteristic of that region, are alien
to the Arctic Flora, Such are the extensive meadows of Grasses and Sedges, the low-
growing forests of Mountain Pines, Alders, and Dwarf Medlars, the scrub of Alpine
Roses (Rhododendrons), and the carpet of prostrate woody plants (Rhamnus pumila,
Daphne striata, Salix retusa, 8. Jacquiniana), besides many other species which
are peculiarly adapted to a substratum of rock or débris, and constitute one of the
chief glories of the Alps. To this category we must also add the particular plants
which, next to the Alpine Roses, are the most commonly recognized representatives
of the Alpine flora, viz. Valeriana celtica, Mewm Mutellina, Primula Auricula,
Artemisia Mutellina, Gnaphaliwm Leontopodiwm (the Edelweiss). The alpine
species of more than 50 genera do not grow at all in the arctic regions, and in the
case of many other genera, though both districts possess a few of the species in
common, it is just those which are peculiarly characteristic of the Alpine Flora that
one seeks for in vain in the extreme north. It would thus be absurd to suppose
that such a flora has migrated from the arctic regions to the Alps, and there is much
more reason for concluding that the scanty flora of the arctic region was in part
derived from the high mountain areas of more southern latitudes.

Researches into the subject of the distribution of Alpine species and of the genera
to which they belong have revealed the fact that some alpine plants occur also in the
higher parts of the Carpathians, in the Caucasus, in the Altai Mountains, and even in
the Himalayas, whilst others are found in the Abruzzi and the Balkans, and upon these
data might be based the hypothesis that the alpine flora was derived from the east
and south, and migrated in the Diluvial Period from the Himalayas, the Caucasus
or the Abruzzi to the Eastern Alps. But the same facts might equally well lead any
one who made a similar investigation of the Alpine flora of the Caucasus or the
Himalayas to infer thati the plants in question had travelled thither from the Alps.
I believe that all such hypotheses involve one in a circle, and bring one no nearer to
the goal. If we wish to solve the question as to what was the place of origin of

906 THE EXTINCTION OF SPECIES.

the plants which took possession of the ground whence glaciers and snow-fields
retreated after the great diluvial ice-age, it is not necessary to look so far afield.
We need only bear in mind that in the period preceding that in which the glaciers
attained their maximum size in the higher mountains of the Alps, a flora must have
existed there, and that this flora would have been forced down from the higher to
the lower parts of the mountains and into the sub-alpine regions by the climatic
vicissitudes which occasioned the glacial condition. In the Tertiary Period the
diminution of temperature accompanying an increase of elevation was doubtless not
materially different from what it is at the present day. The general relief of the
Alps was the same in the Miocene period as it is now; also in the Eocene period, and
even in the more recent portions of the Cretaceous period the Alps were already a
considerable mountain region including probably some high peaks. The Limestone
Alps had their fjords, and the Central Alps were deeply cut into by cross valleys.
The vegetation clothing the lower slopes could not be the same as that of the higher
regions, but, as at the present day, there must have been several floras situated one
above the other. Glaciers must have existed in a latitude of from 46° to 48° at an
elevation of 3000 metres in the highest depressions in the mountains, and that at so
small a distance as 50 kilometres from the sea-coast, and subject to a yearly variation
in temperature of 8°-10° Centigrade; and even though woods of Laurels and Myrtles
flourished in the latter part of the Miocene period of South-eastern Europe on the
spurs of the Alps on the margin of the Wiener Becken, that does not exclude the
possibility of an Alpine flora having developed simultaneously on the snow moun-
tains of that neighbourhood, and on the Rax-alp and the Hochschwab (in the
mountains of Northern Styria). The Carniola Schneeberg to the north of the Gulf
of Fiume affords quite sufficient proof that even a mountain of only 1800 metres
may harbour Laurels and Evergreen Oaks at its feet, whilst alpine vegetation
flourishes on its summits.

The fossil remains of the Miocene flora that are known to us were all discovered
in lowland places, and they therefore only represent the plants belonging to gently
undulating ground or growing on quite low mountains, and no inferences can be
drawn from them as to the nature of the vegetation of the higher regions. I think
that we may fairly deduce the conclusion that the majority of the alpine species
lived on the heights of the Alps as long ago as in the Miocene period, and that the
Alpine Flora though repeatedly forced down to lower levels, always returned again.
As a matter of course the composition of the Alpine Flora underwent many changes
in the process. The partial intermixture of species belonging to adjacent floras
with the alpine species, which must inevitably have taken place in the course of
these displacements, led to inter-crossing and consequently to the production of
new species, whereof a proportion were no doubt adapted to the altered climatic
conditions and capable of preserving their existence. On the other hand, many
of the species which already inhabited the Alps in the Miocene Period have died
out there or have only survived at isolated spots of limited area, as, for instance,
Wulfenia Carinthiaca (see p. 882) in Carinthia, and Rhizobotrya alpina on the

ALPINE AND ARCTIC FLORAS. 907

Passa Alps in Tyrol. This holds especially in the case of the majority of those
species which belong both to the present Arctic Flora and to the present Alpine
Flora. Let us suppose the Alpine Flora driven as far as the North of Germany at
the time of the greatest distribution of the diluvial glaciers. Extensive glaciers had
also advanced far to the south from the north, and had caused a displacement of the
flora indigenous to the Scandinavian Mountains in the Tertiary period as far to the
south as Northern Germany. Thus the floras of the north and of the Alps must
have met there, and when later the climate again became milder a retreat of the
immigrants took place on the one side towards the north, on the other side towards
the Alps. On this occasion some species which previously did not occur in the
Scandinavian Mountains travelled northward, and some hitherto unknown in the
Alps travelled into the Alps. To that epoch must be ascribed the introduction into
Germany of several Arctic species, e.g. Alsine stricta, Sawifraga Hirculus, Pedi-
cularis Sceptrum, Statice purpurea, Salia depressa, Betula humilis, and Juncus
stygiws—which then became dispersed over the low lands lying at the foot of the
Alps in Salzburg and Bavaria, though they did not reach the Alpine region, but
remained behind on the northern border of the mountain area.

The remarkable relations above referred to as existing between the Alpine flora
of the Alps and those of the Carpathians, the Caucasus, the Altai, and the Himalayas,
and also those of the Pyrenees, the Abruzzi, the Dinaric Mountains, and the Balkans
cannot be explained by what took place in the Diluvial period. It has been
ascertained by geologists that the first glaciation of the Alps was not more recent
than, but was possibly even prior to, the third stage of the Miocene Period in the
south-east of Europe, and that during that epoch there could have been no connection
between the high mountain flora of the Alps proper and those of the Carpathians
and the Balkans, not to speak of the mountains lying further to the east or south,
even though the Alpine flora may have descended to a much lower level on the
eastern side. The high mountain floras have hardly met one another either in the
direction of east and west, or in that of north and south. If, therefore, in the
Alps, after the retreat of the glaciers, other species joined forces with those belonging
to the Alpine flora which returned once more to higher regions, these were species
belonging rather to hilly lowlands. Many such species are able to endure the alpine
climate without being injured, and they are represented even at the present day by
large numbers of individual plants both in the lowest parts of the valleys and on
the heights of the Alps. Thus Erica carnea, Globularia cordifolia, and Biscutella
levigata may be traced from the shores of the Adriatic and the banks of Lake
Garda, and from the less lofty heights on the border of the Wiener Becken up into
the alpine region, and may be looked upon as representatives of the plants which
naturalized themselves in that region after the last diluvial ice-age.

If the kinship of the floras growing on the crests and shoulders of the high
mountain chains which succeed one another from west to east and from north
to south is not explicable from what took place in the Diluvial period, we must go
back to an earlier time when either the mountain ranges now separated from one

908 THE EXTINCTION OF SPECIES.

another were continuous or an intermingling and exchange of species were rendered
possible by floral displacements occasioned by vicissitudes of climate. Before the
influx of the first Miocene sea through Servia into Hungary and Austria, the
Bakonyer Wald were joined to the Southern Limestone Alps; peaks of the height
of the Grossglockner lifted their heads where now only low crests surmount the
deposits of the Miocene sea, and those lofty peaks were no doubt clothed with
an alpine flora. Similarly there was then no lack of high mountains covered with
alpine vegetation between the Alps and the Carpathians. Geological information of
this character is certainly of great value when it is a question of explaining the close
relationships existing between the alpine flora of the Eastern Alps and that of the
Carpathians; but the presence of such mountains before the Miocene Period does not
suffice to explain the uniformity of the alpine species, the affinity existing between
the natural groups to which they belong, and the curious overlapping and interlacing
of the boundaries of their areas of distribution on the high mountain ranges which
run from west to east and from north to south. There must also have been at that
time some impelling cause to account for the intermingling of the floras in question,
and for the displacement of their boundaries. The only phenomena which can be
presumed to meet the case are alterations of climate of so drastic a nature as to
cause a simultaneous descent—and subsequently again a simultaneous return—of
the alpine species belonging to the two mountain-chains. These climatic changes
must have been the same as those which culminated in the successive formation and
advance and subsequent retreat of glaciers in those of the mountains which were
lofty enough and of suitable conformation.

In the most widely different strata of our earth’s crust, deposits occur which are
to all appearance moraine-débris, and are looked upon as glacial deposits by every
unbiassed geologist. There is, therefore, good ground for the hypothesis that an
alternate advance and retrogression of glaciers has taken place not only in the
Diluvial period, but also in the Tertiary period, and generally in all the periods dis-
tinguished by geologists. In my opinion the periodical return of a cold, wet climate,
manifested in suitable localities by an increase of glaciers, has everywhere and in
every age been the cause of migrations, and indirectly of inter-crossing, the formation
of new species and the extinction of old ones; and I think that, so far as it goes, it
accounts for the displacements, modifications of type, and other changes undergone
by the various floras in successive geological periods. Mountains have played an
important part in this history. They are able to produce an inexhaustible supply
of plants ever ready to colonize less elevated regions down to the plains below, for
their slopes are the camping-ground of plants adapted to every kind of climate.
When a slight diminution of temperature occurs, the denizens of the lower forest
region spread over the plains; a more considerable access of cold impels the plants
of the upper forest-region to become the invaders, and so on until it comes to the
turn of the vegetation which subsists close to the limit of perpetual snow, where the
snow vanishes for only about 50 days each year. And, just as on occasion of a fall
in temperature, the plants gradually descend the mountain sides and disperse: them-

PERIODIC GLACIATION. 909

selves over the lowlands, so also if the temperature rises they are able to retire to
the heights again. No more need be said to show that the advance and retreat of
vegetation has taken place, and does still take place, pari passu with the growth
and melting away of glaciers.

Very various notions concerning the cause of the periodical return of an ice-age
have prevailed from time to time. Several prominent experts of the present day
believe that alterations in the eccentricity of the earth’s orbit are the cause of the
phenomenon. When the eccentricity increases the earth’s surface is considerably
cooled, and as the eccentricity diminishes the heat increases. A period of great
eccentricity must have begun about 240,000 years before our era and have lasted
16,000 years. Similarly the great eccentricity which existed 850,000 and 2,500,000
years before our era must have brought about repeated glaciation. By others an
alteration of the position of the pole is considered to be the cause of the phenomenon
in question. Much may no doubt be urged against this explanation, but several
phenomena in the plant-world are more easily reconciled with it than with any
other. One example of these is the existence of lofty plants with large foliage in
the Arctic region during the Miocene, Cretaceous, and Carboniferous periods, as is
proved by the discovery of numbers of fossil remains. In the Miocene and Cretaceous
periods, Tulip-trees, Magnolias, Limes, Planes, Bread-fruit trees, and Water-lilies
flourished in North Greenland, Grinnell Land, Iceland, and Spitzbergen. None of
these plants can live there now, for the two following reasons. Firstly, the con-
ditions in respect of solar illumination which obtain there would not permit of their
healthy development; and, secondly, there is not sufficient warmth to enable them
to grow hardily. Since the most eminent geologists of the day have declared
against the idea of the interior of the earth being in a fiery, molten condition it will
not do to attribute to that source the high temperature necessary for great Planes,
Magnolias, and Bread-fruit trees to flourish in such high latitudes. On the other
hand, the presence of large-leaved Angiospermous trees in North Greenland,
Grinnell Land, Iceland, and Spitzbergen would be satisfactorily explained if it
were assumed that the spot which now forms the North Pole—and with it the
whole region now called Arctic—then occupied a different position relatively to the
earth’s orbit, and consequently received a different amount of light and heat.

As regards the history of plants prior to the Eocene and Cretaceous periods no
data are afforded by the investigation of the distribution of living plants, and we
are thrown back on the fossil remains derived from those older periods. These are
unfortunately comparatively scanty, and they no doubt represent but a small
proportion of the species which lived before the Cretaceous period. Two conclusions
may, however, clearly be drawn from these remains, viz.: firstly, that no single main
division existed at that time which is not still represented at the present day; and,
secondly, that some very conspicuous genera of particular groups have died out and
been replaced by other genera of the same groups. Specially noticeable in this
connection are the tree Club-mosses of the Carboniferous period and the Calamites,
species of Horse-tail which must have formed extensive forests in the Carboniferous

910 THE EXTINCTION OF SPECIES,

periods. The occurrence of these curious Calamites of the Carboniferous period
strikes one most when they are found in localities where the ground is now occupied
by low herbs, Mosses, and Lichens, and is covered with snow for three-quarters of
each year, as is the case in ‘Nova Zembla, Spitzbergen, and Bear Island. In the
region of the Alps, too, we encounter spots where this surprising phenomenon is
again presented. One of the most remarkable is the upland valley in the Tyrol
known as the Gschnitzthal. I have for many years passed the summer months in
that valley, and it is there that the greater part of this Natural History of Plants
has been written. The house which I occupy stands at an elevation of 1215 metres
above the sea-level, and is built upon a diluvial moraine in the middle of the valley.
The glaciers which made the moraine have retreated 15 kilometres, and now form
the head of the valley. On its débris, dating from the Diluvial period, now grow
Firs and Pines, Junipers and Heather, all of which are members of the Baltie Flora
Six hundred metres higher up, arboreal growth ceases and the sides and shoulders
of the mountains are clothed alternately with extensive Alpine meadows and scrubs
of Alpine Rhododendrons and carpets composed of Azalea procumbens and of creeping
Dwarf Willows. On the Steinacherjoch, one of the neighbouring ridges, at an
elevation of 2200 metres above the sea-level, the ground consists of dark fissured
slabs of schist, covered with Lichens and Mosses, and here and there overgrown also
by Saxifrages and Primulas. If one of these slabs be split open, the inside is found
to bear the impress of Calamites and giant Ferns of the Carboniferous period.
What an endless series of changes must the vegetation have undergone since the
time when groves of Calamites flourished here. Over and over again has the place
wherein they now repose been turned into the bed of a sea wherein were constructed
the coral reefs which now surmount the dark ancient schist in the form of pale grey
dolomitic peaks. Forest after forest of Coniferous or of Angiospermous trees has
spread its shade over the spot for a time and then passed away. Huge tracts of
ice have filled the entire valley, and upon the débris of the moraines deposited by the
glaciers in their progress now rests a carpet of Primulas, Saxifrages, and Gentians.

“Ebbe und Flut—so wechselt der Tod und das bltihende Leben,
Blumen pflanzet die Zeit auf das vergessene Grab.”

GLOSSARY.

Abscission, the natural cutting off of members by
means of a layer of separation.

Absciss-layer, a layer of separation. See above.

Acaulescent, stemless, or apparently so.

Accrescent, applied to the parts connected with the
flower, as the calyx, &c., which increase in size
after flowering.

Acerosez, Alex. Braun’s term for the Conifere.

Achene, a dry indehiscent 1-celled 1-seeded fruit.

Achlamydeous, used of flowering plants which have
no calyx or corolla.

Acicular, bristle- or needle-shaped.

Acotyledones, old term (De Jussieu) for non-flower-
ing plants.

Acramphibrya, Endlicher’s term for Dicotyledons
and Gymnosperms, regarded as plants growing
both at the apex and at the sides.

Acrobrya, Endlicher’s term for plants growing at
the apex only.

Acrocarpous, said of Mosses which produce their
fruit (sporogonia) at the tips of their shoots,

Acrodromous. See vol. i. p. 633, fig. 1501.

Actinomorphic, applied to flowers which may be
divided vertically into similar halves through two
or more planes,

Aculei, slender, rigid prickles, growing from the
bark, as in the Rose.

Adhesion, the union of parts normally separate.

Adnate, congenitally united or grown together.

Adventitious buds, buds produced out of their
regular order.

£cidium, in Uredinez, a cup-like collection of spores
which are budded off from the base of the cup.

Estivation, the folding of the parts of a flower in
the bud.

Aggregate fruit, a fruit formed by the crowding
together of distinct carpels; the product of a single
gyneeceum when that gynceceum is apocarpous,

Aggregation, the condition of extreme activity of
the stalk-cells of the tentacles of a Drosera-leaf,
resulting from mechanical or chemical stimulation.

Akinetes, in Green Alge, are single cells of the
thallus, whose original walls thicken, and which
separate from the rest of the thallus; they corre-
spond to the chlamydospores of Fungi.

Ale, descriptive term applied to the two lateral
members or wings of a papilionaceous corolla,

Albumen, any form of nutritive matter stored within
the seed and about the embryo.

Albuminous, containing albumen, as in the seeds of
grain, Palms, &c.

Aleurone-grains, grains of nitrogenous food-material
frequently stored in the reserve-tissues of seeds.

Alga, a chlorophyll-containing member of the Thallo-
phyta; one of the plants, the best known of which
are called Sea-weeds,

Alliance, a group of allied families or orders.

Amentaceous, having amenta or catkins; consisting
of or resembling a catkin,

Amentum, a catkin. See Cathkin.

Ameceboid movements, constant changes of shape
resembling those of the ‘Proteus animalcule”
Ameeba.

Amphibious, said of plants such as can live either in
the water or in the air.

Amphibrya, Endlicher’s term for the Monocoty-
ledons.

Amphicarpium, an archegonium when it persists,
after fertilization, as a fruit envelope.

Amphigastria, in Liverworts: certain small scales or
leaves on the ventral side of the oophyte generation.

Amphigonium, used sometimes by Kerner as a
synonym for archegonium.

Amplexicaul, nearly surrounding or clasping the
stem: used of the leaf base in certain cases.

Amylun, starch.

Anaphyte, an old term of the nature-philosophers
by which the potential independence of every
branch or shoot was indicated.

Anastomose, to inosculate or run into each other;
to communicate with each other like arteries and
veins,

Anatomy, the intimate structure of plants.

Anatropous, said of that form of ovule in which,
although the nucellus is straight, the micropyle is
bent down to the point of attachment of the funicle,
and in which the body of the ovule is united to the
funicle, which latter structure is known as the
raphe.

Andrecium, the collective term for the stamens of
a flower.

Androgonidia, the cells which in Volvox give rise to
spermatozoids.

Androspores, name given to the particular zoospores
which in (idogonium give rise to miniature plants,
termed dwarf-males.

Anemophilous, applied to flowers whose pollen is
conveyed by the agency of wind; having flowers
fertilized by wind-borne pollen.

Animalcule, a vague term applied to small motile
organisms in water.

Anisogametes, sexual cells, which show a differen-
tiation into male and female.

Annulus, (1) in Agarics: the ring which often remains
round the stalk (stipe), and was originally attached
to the edge of the pileus; the remains of the velum
partiale; (2) in the Moss-capsule: the ring of cells
which brings about the throwing-off of the opercu-
lum; (8) in the Fern-sporangium: a conspicuous
row of cells running vertically, obliquely, &c., around
the sporangium, by the contraction of which dehis-
cence takes place.

Anophyta, Endlicher’s term for the Muscinez,

912

Anther, the polliniferous part of a stamen; the sac
or cavity in which the pollen is contained.

Antheridium, a male sexual organ, usually producing
motile spermatozoids.

Anthocyanin, a purple sap-pigment frequent in
foliage and flowers.

Antholysis, literally a “loosened” flower, te a
flower in which the various parts have become more
or less foliacious, and from which inferences can be
drawn as to the morphological nature of the com-
ponent parts.

Anthophyta, Alex. Braun’s name for the Phanero-
gamia.

Anthoxanthin, the yellow pigment of flowers and
fruits.

Antipodal cells, a group of three cells at the chala-
zal end of the embryo-sac of Angiosperms.

Apetalz, Dicotyledons destitute of a corolla.

Aplanospore, a non-motile asexual reproductive cell
of the Green Alge.

Apocarpous, said when the carpels of a gynceceum
are separate.

Apophysis, a swelling under the base of the theca in
some Mosses.

Apothecium, the disc-like receptacle of an Ascomy-
cetous Fungus.

Arbor, a tree.

Arbuscula, a little or dwarf tree.

Archegonium, in the higher Cryptogams the flask-
shaped female sexual organ with neck and venter,
the latter containing an egg-cell, the former canal-
cells.

Archesporium, a cell or group of cells from which
spore mother-cells are produced.

Archichlamydez, a large group of Dicotyledons,
including the old groups Polypetale and Incom-
pletz.

Areolated, marked with little areas; divided into
small areas by intersecting lines.

Aril, an investment to a seed which arises after ferti-
lization. It is usually succulent.

Arthrospore, a form of spore produced in the Schizo-
mycetes by the segmentation of the tubes into cells.

Arundinaceous, reed-like.

Ascidiform, like a pitcher; pitcher-shaped.

Ascidium, a pitcher; an appendage somewhat re-
sembling a pitcher. See Pitcher.

Ascus, a form of sporangium characteristic of certam
Fungi. It is generally tubular and contains eight
spores, the ascospores.

Ash, the inorganic residue which is left after a plant
has been burned.

Assimilation, as used here, the building of a plant-
substance from the nutriment of the environment.
Often restricted to the manufacture of carbo-hydrate
from carbonic acid and water.

Asyngamic, used of plants which are prevented from
intercrossing by the fact of their non-simultaneous
periods of flowering. Nearly related species can
thus inhabit the same spot without hybrids ever
being formed.

“Attire ’’, an archaic term, applied by Grew to the
stamens,

Auricle, an ear-shaped appendage.

Autogamy, self-pollination, ultimately self-fertiliza-
tion.

Autonomous movements, spontaneous; originating
from inherent tendency,

GLOSSARY.

Auxospore, the reproductive cell of a Diatom. See
vol. ii. p. 626.

Awn, « bristle-like appendage, especially in the
glumes of Grasses.

Axis, essentially the stem. The root is also an axis.

Azygospore, term given to the “zygospore” when
it is formed parthenogenetically with conjugation.

Bacterium, one of the micro-organisms concerned in
putrefaction: a term rather widely applied to any
member of the Schizomycetes.

Barbs, the retrorse appendages of bristles, or the
teeth on leaf-margins.

Bark, the usually hard outer investment of a peren-
nial stem (or root) which has arisen in connection
with a cork-cambium ; actually it includes the
products of the cork-cambium and whatsoever is
external to it.

Basidium, a cell from which spores or conidia are
produced by a process of abstriction.

Bast, inner bark; a special tissue: soft-bast, the
phloem—includes sieve-tubes and other non-har-
dened phloem-elements; hard-bast, the thickened
prosenchymatous elements or bast-fibres.

Bastard, a term sometimes given to a hybrid.

Bedeguar, name given to the mossy red galls on
the common Wild Rose.

Berry, a fruit the whole pericarp of which is succulent.

Bilabiate, two-lipped.

Bizzaria, a fruit, part Orange, part Citron.
ii. p. 569.

Blendling, a name given to a hybrid arising by the
crossing of “races”.

Blossom, cf. vol. ii. p. 71.

Brachydodromous, used of leaf-veins.
p. 630.

Bract, a leaf subtending a flower.

Bract-scale, the lower member of the duplex scale
of the female cone of Pine, Fir, &c.

Break back, a term used by gardeners to convey the
idea of reversion. Thus flowers break back or revert
to an ancestral type.

Bud, the as yet unexpanded rudiment of a shoot; it
comprehends both axial and foliar portions.

Bulb (bulbus), a bud consisting of an abbreviated axis
with fleshy scale-leaves in which food-material is
stored. Usually subterranean.

Bulbil, a deciduous bud, usually formed on an aérial
part of a plant. Occasionally used for a little bulb.

See vol.

See vol, i.

Callus, the healing tissue which closes up the wounds
of plants. The same term is given to a mucilaginous
substance which arises on the sieve-plates of the
sieve-tubes, closing them. The latter is of course
quite a different structure, and to distinguish it
from the former may be called callose.

Calyptra, the hood which is raised up on the sporo-
gonium of a Moss. It is the ruptured upper portion
of the archegonium.

Calyx, the outer whorl of the perianth, consisting of
sepals.

Cambiform cells, cells resembling cambium cells;
thin-walled, tapering cells found in the phloem ac-
companying the sieve-tubes, companion-cells, and
bast-fibres.

Cambium, a layer of tissue formed between the wood
and the bark, and consisting partly of nascent wood,
partly of nascent bark,

GLOSSARY.

Campylodromous, applied to the manner in which
veins are distributed. See vol. i. p. 633, fig. 1503,
Campylotropous, used of an ovule or seed in which
the nucellus, with its integuments, is bent so that
the apex is brought near to the point of attachment.

Canker, a vague term applied to the disease or Fungus
which attacks plants and causes slow decay.

Capillitium, the thread-like fibres, often united into
a reticulum, which are developed within the spores
of Myxomycetes and many Gasteromycetes.

Capitulum, a head or globular cluster of sessile
flowers.

Caprification, the custom of hanging branches of the
wild Fig in the cultivated trees so as to ensure pol-
lination by means of the gall-insects thus introduced.

Caprificus, the uncultivated male form of the com-
mon Fig.

Capsule, a dry, dehiscent fruit.

Carobe di Giude, Turpentine Gall-apple, produced
on Pistacia Lentiscus by a Pemphigus.

Carpel, a single-celled ovary or seed-vessel, or a single
cell of an ovary or seed-vessel together with what
belongs to that cell; it may be regarded as a modi-
fied leaf.

Carpium, or Carp, the oogonium modified by fertili-
zation, which remains as an envelope around the
embryo. Cf. vol. ii. p. 47.

Carpo-asci, the more complex Ascomycetous Fungi
—all except the Exoascacez.

Carpophylla, the carpels.

Caruncle, a localized outgrowth of the seed-coat; a
sort of aril.

Caryophyllaceous, appertaining to the Pink family.

Caryopsis, an indehiscent one-seeded fruit, in which
the thin seed-coat adheres to the pericarp, as in all
cereal grains.

Catapult-fruits, fruits in which the dispersal of the
seeds or fruit-segments is due to the elastic reaction
of the resilient peduncles or pedicels.

Catkin, a pendulous inflorescence bearing flowers of
one sex only; an amentum.

Caudex, a trunk or unbranched stem.

Caudex columnaris, an erect columnar stem, as in
Palm-trees.

Caulescent, having an obvious stem rising above the
ground.

Cauline, appertaining to the stem.

Caulis, the stem or stalk.

Caulis herbaceus, a herbaceous stem.

Caulis suffruticosus, a suffruticose stem; the stem
of an under-shrub.

Caulome, a stem-structure, or the stem-like portion
of a plant.

Cecidium, a gall or hypertrophy on a plant-member,
due to the stimulating action of an insect or Fungus.

Cell, the structural unit in the formation of plants;
one of the individualized portions of which plants
are built up.

Cell-membrane, the cell-wall.

Cell-plate, used here of aggregates of cells in one
plane.

Cell-sap, the watery fluid contained in a cell.

Cellular, consisting of cells. Sometimes used of
plants which are destitute of vessels.

Cellulose, a carbo-hydrate of which cell-membranes
are composed ; the essential constituent of cell-walls.

Centrifugal, a term applied to such inflorescences as
develop from the centre outwards.

Vou, IT.

913

Centripetal, a term applied to such inflorescences as
develop from without inwards.

Cephalonion gall, a sac-like gall joined to the leaf
by a narrow neck.

Ceratonion gall, a hollow, thick-walled, horn-like
gall, belonging to the series of Mantle-galls.

Chalaza, the part of an ovule where nucellus and
integuments cohere; the base of the nucellus.

Chalazogamic, applied to fertilization in flowering
plants via the chalaza and not by the micropyle, e.g.
in the Hazel.

Chlamydospore, the reproductive organ in some
Fungi.

Chloranthy, the production of green flowers; a sup-
posed reversion of floral structures to a primitive
foliar condition.

Chlorenchyma, a term sometimes given to a green,
chlorophyll-containing tissue.

Chlorophyll, the ordinary green pigment of plants
which is the agent in the process of carbon assimi-
lation.

Chlorophyll-corpuscles, protoplasmic bodies distinct
from, yet imbedded in, the general cell-protoplasm
of the green parts of plants. The chlorophyll is
restricted to these corpuscles.

Chromatophore, a general term for any protoplasmic
body containing a pigment. Chlorophyll-corpuscles
are chromatophores.

Chromosomes. See Fibrils.

Cilia, delicate protoplasmic filaments serving as organs
of locomotion, as in zoospores, &c.

Cincinnus, a form of cymose inflorescence, a one-sided
cyme.

Cirrhus capreolus, a term for stem-tendrils, ie.
branch-tendrils and flower-stalk tendrils.

Cirrhus costalis, a projecting or excurrent midrib,
modified as a tendril.

Cirrhus foliaris, a leaf modified as a tendril.

Cirrhus peduncularis, a flower-stalk modified as a
tendril.

Cirrhus petiolaris, a petiole or leaf-stalk modified
as a tendril.

Cirrhus radicalis, a root modified as a tendril.

Cirrhus rameaneus, a tendril which is a modified
branch.

Cirrhus stipularis, a tendril which is a metamor-
phosed stipule.

Cladodes, leaf-like branches. See Phylloclade.

Clamp-cells, here used for the papilla-like cells by
which an epiphytic root adheres to the substratum.

Class, the highest grade or division of plants in the
system of Linneus. In our system a class is sub-
ordinate to a phylum, and the classes are subdivided
into alliances.

Clavate, club-shaped.

Claw, a name given to the stalk of a petal.

Cleistogamic, -ous, a term applied to the inconspi-
cuous flowers produced by many plants. These
flowers do not open, and are self-pollinated (autoga-
mous).

Cob, a term applied to the spike on which Maize
grows.

Ccenobe, or Ccenobium, a colony of separate organ-
isms united by a common investment, ¢.g. Volvox.

Coherent, used of the union of similar members.

Cohort, a group of families or orders which are
nearly related to one another ; is used here as syno-

nymous with Alliance,
= 108

914

Collective fruit, a fruit in which the products of a
number of separate flowers become so crowded to-
gether as to appear as though they had arisen from
a single flower, as the Pine-apple. Cf. Aggregate
fruit.

Collenchyma, a living tissue, consisting of prism-
shaped cells whose angles are much thickened. It
is a form of mechanical tissue.

Colony. See vol. i. p. 585.

Columella, in Muscinex, the sterile tissue in the
centre of the sporogonium around which the spore-
layer is formed.

Column, the body formed as a result of fusion of
stamens with style, as in Orchid flowers.

Conceptacle, the inclosing cavity in which the sexual
organs are produced in the Fucacez.

Cone, the aggregate of crowded scales which bear
ovules or pollen-sacs in the Gymnosperms ; applied
also to the sporangiferous branches in many Vascular
Cryptogams.

Conidium, in Fungi, a propagative asexual body.

Conifer, a plant producing cones; one of the Conifer.

Conjugation, the union of two gametes (or sexual
cells), the resulting organism being called a zygote. ,

Conjugation-canal, the bridge which is formed
between conjugating cells of Spirogyra, &c., and by
which impregnation is effected.

Connate, united congenitally.

Conopodium, a conical receptacle (used of flowers).

Contorted zstivation, used when the corolla appears
spirally twisted, the petals being so arranged that
one margin is external to a neighbouring petal
whilst the other is internal to the petal on the other
side.

Contractile cells, in the anther, form a layer in its
wall; their membranes are peculiarly thickened, and
by their hygroscopic contractions the anther opens,

Convolute, applied to a leaf which is rolled up longi-
tudinally in the bud.

Cordate, heart-shaped, as a leaf.

Corm, a bulb-like fleshy stem or base of a stem; a
“solid bulb”, as in Crocus, Colchicum, &c.

Cormus. See foot-note, vol. i. p. 665.

Corolla, the inner whorl of the perianth, composed of
petals,

Corona, in Narcissus, &c., a series of ligular struc-
tures on petals, which may be either free or united
together. It gives the appearance of an additional
floral whorl.

Corpuscle, a little mass of protoplasm which though
imbedded in the general protoplasm of the cell is
nevertheless an independent body, eg. chlorophyll-
corpuscle.

Corpusculum (of Asclepiad pollinium), the little body
connecting the pollen-masses and by means of which
they become attached to insects.

Cortex, the portion of a stem or root external to the
vascular tissues.

Corymbus, or Corymb, a, flat-topped inflorescence
belonging to the centripetal or indefinite series.

Cosmic dust, the minutely divided inorganic particles
suspended in the higher strata of the atmosphere ;
not necessarily of extra-terrestrial origin.

Cosmopolitan plants are such as range almost over
the entire globe; in contrast to plants that flourish
only in a certain locality (endemic plants),

Cotyledons, seed-leaves; the first leaf or leaves of
an embryo.

GLOSSARY,

Craspedromous, used of the lateral veins of a leaf
which run undivided from midrib to margin.

Crateriform, goblet- or cup-shaped.

Crenate, said of a toothed leaf-margin, the teeth being
rounded ; scalloped.

Cross-fertilization, the fertilization of an egg-cell
by a male cell borne on another individual ; fertili-
zation of the ovules of one flower by the pollen from
another individual, Occasionally used in error in
the text for cross-pollination (which see). Many
authors use the term as synonymous with cross-
pollination, but the practice is not good.

Cross-pollination, the deposition on a stigma of
pollen which has been brought from another flower.
Cross-pollination, though probably leading to cross-
fertilization, is not synonymous with this term.

Cruciferous, “cross-bearing”’, having cross-shaped
flowers: used of the characteristically flowered family
Cruciferze.

Cryptogamia, includes all plants exclusive of Flower-
ing Plants: opposed to Phanerogamia. An old
term, persisting from times when the reproductive
processes of these plants were less well-known than
to-day.

Crystalloid, a crystal-like mass of proteid; 2 common
form under which proteids are stored.

Culmus, or Culm, the jointed and usually hollow
stem of Grasses and similar plants.

Cupule, the bract-like cup which incloses the nut or
nuts in many Amentifere; it is the husk of the
hazel-nut, the cup of the acorn, the prickly envelope
of the Spanish chestnut, &c.

Cut, a term applied to the lobing of leaf-blades;
incised ; cleft.

Cuticle, a continuous film on the surface of a plant,
formed of the cutinized outer surfaces of the epider-
mal cells.

Cyma, or Cyme, a definite or centrifugal inflores-
cence: the laterals grow more strongly than the
primary axis and overtop it.

Cyma composita, or compound cyme; a definite or
centrifugal inflorescence, in which the ultimate parts
(cymes) are also arranged in a cymose manner.

Cystolith, a concretion of carbonate of lime, gener-
ally deposited on a little tongue or peg of cellulose
projecting into the cells of certain plants.

Cytoplasm, the protoplasmic body of a cell as op-
posed to the nucleus.

Daughter-cells, cells which arise by the division
of any cell,

Deciduous, non-permanent: used of parts of a flower
(petals, &c.) which fall after flowering, and of
leaves which fall in autumn, &c.

Decurrent, used of leaf-blades which have their bases
extending downward along the stem.

Decussate, applied to leaves which are arranged
in pairs alternately crossing each other at regular
angles,

Definitive nucleus, the nucleus which is formed in
the embryo-sac by the fusion of two, one from each
end; the endosperm originates from it after fertili-
zation has taken place.

Dehiscence, the act or mode of opening of a fruit,
anther, spore-capsule, &c. &c.

Dendritic, tree-like ; repeatedly branched.

Denizen, an inhabitant, a plant belonging to a cer-
tain district, Strictly (but not so used in K. and

GLOSSARY.

0.), @ plant resembling a native, but suspected of
having been originally introduced.

Dentate, of leaf margins; toothed—the teeth point-
ing outwards, not forwards or backwards.

Dermatogen, the embryonic cellular layer at the
apex of a stem or root from which the epidermis
is developed.

Desmid, one of the Conjugate. See vol. ii. p. 655.

Dextrorse, used of twining plants which turn from
west through south to east, &c.

Diadromous, having a fan-like arrangement of leaf-
veins, as in Gingko.

Dialypetalz, plants with petals separate from one
another (= Polypetale).

Diandria, the 2nd class of Linnean system; includes
all genera with perfect flowers having two stamens.

Diastase, a solid, white, soluble substance found in
Oats, Potatoes, &c., after germination.

Diastole, used of the rhythmic expansion of a con-
tractile cell or vacuole.

Diatom, a single organism inclosed in a bivalved
siliceous test or frustule. See vol. ii. p. 625,

Diatomin, the brown pigment of Diatoms.

Dichogamy, the maturing of pollen and stigma in a
hermaphrodite flower at different times, to prevent
self-fertilization.

Dicotyledon, plant with twoseed-leaves or cotyledons.

Dictyodromous, or reticulate venation, are terms
applied to lateral veins of leaves which break up
into a network before reaching the margin.

Didynamia, the 14th class of the Linnean system,
which includes flowers with four stamens, two long
and two short.

Didynamous, applied to flowers having four stamens,
one pair longer than the other.

Dicecious, unisexual; the male and female flowers
being on separate plants.

Diosmosis, the transfusion of a fluid through im-
perceptible openings in a membrane.

Diptero-cecidia, gall-structures, due to dipterous
insects.

Discoid, resembling a disc.

Discomycete, any Fungus belonging to the group
Discomycetes, z.e. an Ascomycete in which the fruit-
ing body is disc-shaped.

Discomycetous, pertaining to the group of Fungi
Discomycetes.

Discopodium, a disc-shaped floral receptacle.
Disintegration, a resolution of a tissue into its con-
stituent cells, or of any body into its constituents.
Displacement, in whorls, applied to the shifting of
places of insertion of members, so that successive
whorls are placed immediately above one another.

Divergence, applied to the angle between the inser-
tions of successive leaves on a stem.

Divided, used of leaf-blades to express the fact that
they are deeply lobed.

Dormant eyes or buds, or Reserve-buds; are buds
which arise in the leaf-axils in the usual way, but
which do not forthwith expand into shoots; they
remain—often many years—until stimulated into
activity by some special event.

Drupaceous, of the nature of a drupe.

Drupe, a succulent fruit with hard, stony endocarp,
which incloses a single seed. Many-seeded drupes
are rare.

Duct, a continuous tube, arising either by the run-
ning together of cells (fusion), or by the separation

915

of cells, when it is lacunar in nature; a canal formed
by a row of cells having lost their partitions.

Dwarf-male, of CEdogonium; the little few-celled
plant arising from an androspore which gives rise
to the spermatozoids, It is formed adjacent to the
oogonium.

Ectoplasm, the pellicle-like outmost layer of proto-
plasm in a cell. It is clear and hyaline, and less
fluid than the endoplasm.

Egg-cell, or Ovum; the female generative cell.

Elaters, (1) in Liverworts, filamentous cells, with
spiral thickenings, which are present with the
spores, and, owing to their hygroscopicity, assist in
their dispersal; (2) in Equisetum, arm-like append-
ages of the spores, by the contractility of which
the spores become entangled in groups.

Ellipsoidal,. having the form of an elliptical solid.

Embryo, the rudimentary plant; in seeds, that stage
of the young plantlet at which the resting-stage
supervenes.

Embryo-cell, the cell borne at the distal end of the
suspensor, which gives rise to the embryo, or to the
greater part of it.

Embryo-sac, the large cell in the nucellus of an
ovule, in which the egg-cell, and ultimately the
embryo, arises.

Endemic, restricted to a given region or locality.
Endophytic, living within the tissues of another
plant, though not necessarily parasitic upon them.
Endoplasm, the soft, inner granular protoplasm of a

cell.

Endosmosis, the transmission of fluids through
porous membranes from the exterior to the interior.

Endosperm, the tissue produced within the embryo-
sac of flowering plants, and which in many cases
becomes stored with food-materials for the embryo.

Endospores, asexual reproductive cells produced
inside the original cells in Bacteria.

Endothecium, in flowering plants, the layers of the
wall of the anther internal to the exothecium.

Ennobling, the art of transferring a branch or bud
of one plant to another, and causing them to unite.

Entire, untoothed: applied to the leaf-margin, petals,
&e,

Entomophilous plants, such as have flowers pollin-
ated by insect agency.

Enzyme, any of the unorganized ferments which
exist in seeds, as diastase, pepsin, &c.

Ephemeral, applied to flowers which endure only for
a few hours or for a day; opening but once.

Epicotyl, the portion of a plant above the cotyledons ;
restricted to embryos and seedlings.

Epidermis, that layer of cells which forms the envel-
oping mantle of multicellular plant-bodies. It may
be replaced in perennial plants by cork.

Epigeal, growing above the ground.

Epiphragm, of Mosses: the membrane remaining
after the fall of the operculum, stretched across the
mouth of the capsule in Polytrichacez.

Epiphyllous, applied to structures growing on leaves.

Epiphytes, plants growing attached to other plants
(or animals), but not parasitically.

Equitant, riding; folded around, as if straddling
over.

Erythrophyll, a red sap-pigment frequent in foliage-
leaves, especially in autumn.

916

Ethereal oils, oils of wide occurrence in plants, and
of various chemical composition ; to the presence of
these ethereal or volatile oils are due most of the
odours of plants.

Evolute, turned back.

Exalbuminous, applied to seeds which are destitute
of endosperm or perisperm, the food-material being
stored in the embryo itself. ;

Excoriation, of glandular hairs; applied to the act
of throwing off the cuticle as a blister.

Exfoliate, to come away in scales or flakes, as the
bark of a tree.

Exine. See Eaxtine.

Exogamy, the tendency often exhibited by closely
related gametes to avoid pairing.

Exosmosis, the passage from within outwards of
fluids through a membrane.

Exothecium, the outmost layer or epidermis of an
anther.

Exstipulate, without stipules: often used (though
erroneously) in cases where the stipules are early
deciduous.

Extine, the outer coat or membrane-layer of a pollen-
grain. It is, however, internal to the perine.

Extravasation, an escape from the proper vessels into
surrounding tissues: used of fluids.

Extrorse, applied to such anthers as open towards
the outer whorls of a flower, t.e. away from the
gynceceum.

Eye, of Potato, &c.; an undeveloped bud.

Eye-spot, in motile gametes and spermatozoids, a
little red pigment-body contained usually in the
anterior extremity, and supposed to be sensitive to
light. Cf. vol. ii, p. 629.

Fairy-ring, a phenomenon observed in meadows, and
due to the growth of certain Fungi. Cf. vol. ii.
p. 792.

Fasciation, used of monstrous expansions of stems,
which resemble several stems fused together in one
plane,

Fascicula, or Fascicle, « dense cluster of flowers,
leaves, roots, &c.

Father-plant, the stock from which the pollen is
derived: used in connection with hybrids.

Ferment, a substance produced by the protoplasm,
which induces chemical change or fermentation in
some substance without itself entering into or being
affected by the process,

Fertilization, the process by which the pollen reaches
and acts upon the ovules, and results in the produc-
tion of fruit; impregnation.

Fertilizing-tube, in Peronospora, the tubular out-
growth of the antheridium which penetrates the
oogonial wall and by which the male substance
passes to the egg-cell.

Fibre, any delicate filament; also, a thick-walled
tapering cell,

Fibrils of nucleus; the segments into which the
nuclear reticulum breaks up at division; they are
also termed chromosomes.

Fibrous layer, of anther: the specially thickened
portion of the wall which brings about dehiscence,

Filament, the stalk of an anther,

Filiform, slender, thread-like,

Fimbriate, fringed by fine subdivision of the margin;
having fine, hair-like marginal processes,

Fistular, hollow, reed-like,

GLOSSARY.

Flagellum, the whip-like process or filament of proto-
plasm which serves as an organ of motility; also a
shoot sent out from the bottom of a stem, as in the
strawberry ; a runner.

Floccose, composed of or bearing soft hairs or wool.

Flora, the aggregate of the plant-population of any
district; also, the term given to a systematic descrip-
tion of the same.

Floral, belonging to the flower.

Floret, « small flower in a cluster or in a compact
inflorescence, as in the Composite.

Flower, in Phanerogams the growth which comprises
the reproductive organs and their envelopes; a shoot
modified for the production of spores (pollen-grains
and embryo-sacs).

Flowering glume, the outer of the two chaffy scales
inclosing the several flowers of a grass; it is fre-
quently awned,

Folium fulcrans, the subtending leaf of a flower;
a bract.

Follicle, a monocarpellary dehiscent fruit opening
only down the ventral suture.

Foot, the sucker by means of which a young Fern-
plant is temporarily attached to.the prothallium.

Foreign, applied to pollen from another flower.

Frugivora, animals which live upon fruits.

Fruit, defined vol. ii. p. 47.

Frustule, the siliceous valve of a Diatom.

Frutex, a shrub.

Fruticose, pertaining to shrubs; shrubby.

Fruticulus, a little shrub.

Fuliginous, having the colour of soot.

Fundamentum, the hypocotyl, which see.

Fungus, a cellular Cryptogam, distinguished for its.
want of chlorophyll; it is either saprophytic or
parasitic.

Funicle, the stalk of an ovule or seed; a funiculus.

Furfuraceous, scurfy; covered with bran-like scales.

Fusiform, spindle-shaped: applied to roots, &c., which
taper both ways from the middle, as the radish.

Galeate, helmet-shaped; having a galea or helmet.

Gall, a vegetable excrescence produced by the deposit
of the egg of an insect in the bark or leaves of a
plant; a hypertrophied growth due to some irritat-
ing cause.

Gametangia, cells from which gametes are developed.

Gamete, a sexual cell,

Geitonogamy, crossing between separate flowers
growing on the same plant.

Gemma, a small undeveloped shoot; a shoot-bud.

Gemmation, the act or process of budding.

Generative cell, in pollen-grains, that cell which
ultimately fertilizes the egg-cell.

Genetic spiral, the spiral line passing through the
point of insertion of equivalent lateral members
(leaves) on an axis in order of age from older to
younger.

Genus, an assemblage of species; its name, together
with that of the species, gives the name to the
plant.

Geotropism, applied to the power or tendency of
some plants to grow towards the earth.

Germen, the ovary.

Germination, the act, process, or result of evolving
the embryo of a seed into a young plant. *

GLOSSARY.

Gills, the radiating plates on which the basidio-
spores of Agarics are produced.

Glabrous, without hairs; quite smooth,

Glandular, having the nature of a gland, bearing
glands,

Gleba, the chambered, sporogenous layer of a Gas-
teromycetous Fungus.

Globoid, the tiny mass of magnesium and calcium
phosphate which is often present in aleurone grains
(which see).

Glomerule, a cymose inflorescence formed into a
head, as in the Globe-thistle.

Glucoside, a compound consisting of glucose and an
aromatic body.

Glumes, the chaffy, bract-like scales on the inflores-
cences of Grasses and Sedges.

Goneoclinic, used of hybrids which approximate to
one or other parent-form rather than standing mid-
way between them.

Graft-hybrid, a hybrid supposed to have arisen by
budding or grafting.

Gynandria, the 20th class of the Linnean system.
Cf. vol. ii. p. 290.

Gynoeceum, the carpel, or aggregate of carpels, in a
flower; the female portion of a flower as a whole.

Habitat, the natural abode of a plant.

Hematochrome, the red pigment found in the eye-
spots of Chlamydomonadee and zoospores.

Halophytes, plants which flourish on soils rich in
salt; saltworts.

Haulm, the stalk of a grass of any kind.

Haustorium, the sucker of a parasitic plant.

Herbaceous, of the colour, texture, &c., of a herb.

Herbal, a book of descriptions of plants with especial
reference to their medicinal properties; herbals
were usually copiously illustrated.

Herbarium, a collection of dried plants systemati-
cally arranged. (Formerly it signified an illustrated
herbal.)

Hermaphrodite, applied to a flower which has both
stamens and carpels.

Heterochromatism. Vide vol. ii. p. 569.

Hetercecism, the act of passing through different
stages of development on different hosts; as in
Fungi.

Heterogamous, applied to plants that bear two
kinds of flowers which differ sexually. _

Heterogamy, the state or quality of being hetero-
gamous (which see); cross-pollination.

Heteromorphism, here used to designate the various
modifications of equivalent members in connection
with different functions, analogous to that existing
among the polyps of a coral.

Heterophyllous, bearing leaves of more than one
form on the same stem; applied especially in respect
of foliage-leaves.

Heterosporous, having spores of different kinds,
especially macrospores and microspores.

Heterostyled, when the flowers of a plant differ in
the relative length of their styles: opposed to homo-
styled.

Hilum, (1) of starch-grain; the centre around which
the stratifications are deposited ; (2) of a seed; the
scar or place of attachment.

Hirsute, bearing rather stiff hairs.

Holosericeus, covered with fine silky hairs.

917

Homochromatism. Vide vol. ii. p. 569.
Homosporous, having spores all of a kind.
Homostyled. See Heterostyled.

Hortus vivus, an old term for a dried collection of
plants, now called a herbarium (hortus siccus is also
used in the same sense).

Humus, vegetable mould; a soil largely composed of
decaying vegetable matter.

Hybrid, a plant resulting from the intercrossing of
more than one species,

Hybridization, the act of crossing different species
and so producing hybrids.

Hydrophytes, plants which live in water.

Hydrotropism, the particular irritability of plant-
members (especially roots) whereby they respond by
curvatures to moisture in the environment, turning
towards or away from it.

Hymenium, hymenial layer; the spore-bearing sur-
face of a fungal receptacle.

Hypanthium, a term given to any special enlargement
of the receptacle, as in the Rose.

Hypha, the filamentous element of the thallus of a
Fungus.

Hyphodromous, used when the veins of a leaf
run so that they are not visible on the surface.

Hypocotyl, the portion of the stem below the coty-
ledons.

Hypocrateriform, salver-shaped: used of corollas,
&c., which are tubular below and suddenly expand
into a flat limb.

Hypogeal, underground; growing beneath the surface
of the earth.

Hysterophyta, Endlicher’s term for the parasitic
flowering plants.

Idioplasm, name applied by Negeli to that portion
of the protoplasm in which the formative activity
was supposed to reside —the active, organizing
portions of the protoplasm.

Illegitimate union in heterostyled flowers. Vide
vol. ii. p. 405.

Imbricate zstivation. Vide vol. ii. p. 210.

Imbricating, overlapping like the tiles of a roof.

Incised, of leaves, cut irregularly and sharply.

Indumentum, a hairy covering or coating.

Indusium, the scale-like outgrowth of a Fern leaf
enveloping the sorus.

Inferior, (1) of the ovary; adherent to the calyx (cf.
also vol. ii. p. 79); (2) of the calyx, free from the
ovary; (3) in regard to the relation of parts of
flower to the axis; farthest from the axis.

Inflorescence, the mode of branching of the flower-
bearing part of a plant; or, the actual cluster of
flowers (the common use of the term).

Infundibuliform, Infundibular, funnel-shaped.

Innovatio, a new-formed shoot.

Insectivorous plants, plants which catch insects
and absorb their juices.

Integument, the envelope—single or double—of an
ovule.

Internode, the portion of a stem between the points of
insertion of leaves.

Intine, the internal layer of the wall of a pollen-grain.

Introrse, of the anther; dehiscing towards the centre
of the flower.

Intussusception, the taking up by a living organism
of new particles between those already in existence.

918

Invertin, a ferment which converts cane-sugar into
glucose.

Involucral, appertaining to the involucre.

Involucre, a circle of bracts inclosing a capitulum
or other crowded inflorescence.

Involute, rolled inward.

Isogametes, equivalent gametes or sexual cells.

Isoplanogametes, in Algz; motile sexual cells which
are equal in size.

Kamptodromous. See vol. i. p. 630.

Labellum, the median member of the inner perianth-
whorl in Orchids.

Laciniated, cut into narrow lobes.

Lacuna, a space, especially an intercellular space,
originating by the separation or breaking down of
cells,

Lamella, a thin plate as in the gills of Agarics. See
Gills.

Lanceolate, shaped like a lance-head; narrower
than oblong, and tapering towards the apex.

Latex, plant juice, often a milky juice.

Laticiferous, containing latex.

Leaf-axil, the angle formed by a leaf and the por-
tion of stem immediately above its point of inser-
tion.

Leaves, laterally -developed members of limited
growth, which spring in geometrical succession
from the outer layers of tissue below the growing
point of the stem.

Legitimate union, in heterostyled flowers.
vol. ii, p. 405.

Legume, or Pod; a monocarpellary fruit dehiscing
down both sutures.

Lepidote, -us, beset with scurfy scales.

Liane, Liana, a climbing plant with a woody, peren-
nial stem.

Libriform cells, strong, spindle-shaped cells with
inconspicuous pittings, thick walls, and usually
destitute of protoplasmic contents. They occur in
wood.

Lichen, an organism compounded of a Fungus and an
Alga living together symbiotically.

Lignin, an aromatic substance (or number of sub-
stances) present in the membrane of woody tissue.
To it are due the characteristic properties of wood.

Ligulate, provided with a ligule.

Ligule, Ligula, (1) the thin scarious projection from
the summit of the leaf-sheath in Grasses; (2) the
corolla of a ray-floret in the Composite; (8) a
tongue-like outgrowth on the leaf met with in Sela-
ginella and Isoétes just above the insertion of the
sporangium.

Linear, several times narrower than long, with the
margins parallel.

Linear-lanceolate, intermediate in form between
linear and lanceolate.

Lines of vegetation, for any species, are the lines
obtained by joining all the places in a given direc-
tion at which that species is checked in its distribu-
tion by climatic or other conditions; the resultant
figure obtained by joining all the lines of vegetation
covers the distribution of the species in question,
and may be termed the line of distribution.

Lithophytes, plants which grow on stones, and
derive their nutriment in the main from the atmo-
sphere.

Vide

GLOSSARY.

Liverwort, a term applied to any member of the
Hepatica. ae
Lobe, any division of an organ; a rounded projection
or division. ;
Lodicules, tiny scales, usually two in number, which
occur in the flowers of Grasses, and are supposed to
represent the perianth.

Lomentum, a legume which separates into 1-seeded
articulations or joints.

Macropodous, applied to embryos in which the
hypocotyl is enormously enlarged, constituting the
greater part of the embryo.

Macrospores, used of the larger (so-called female)
spores of heterosporous plants: opposed to micro-
spores.

Manubrium, the cell in the antheridium of Chara-
cee which projects inwards from the shield, and
ultimately bears the antheridial filaments.

Medulla, pith.

Megagametes, used of the larger, and presumably
female, motile sexual cells of certain Alge.

Melliferous, honey-bearing.

Mericarp, one of the achene-like fragments into
which a syncarpous, polycarpellary fruit (schizocarp)
breaks up. Used especially of Umbelliferz.

Meristem, embryonic tissue: growing cell tissue at
the ends of young stems, roots, &c.

Mesophyll; the whole of the internal ground-tissue
of a leaf-blade.

Metabolism, the chemical changes which take place
in the protoplasm and which it causes in other sub-
stances; the phenomena resulting from chemical
changes in the protoplasm.

Micelle, name given to molecular aggregates, just as
molecule is the name given to atomic aggregates.
Microgametes, used of the smaller, presumably male,

motile sexual cells of certain Algae.

Micro-millimeter (), the one-thousandth part of a
millimeter.

Micropyle, the aperture left in. the integument of
an ovule by means of which the pollen-tube gains
access (except in chalazogamic plants) to the
embryo-sac.

Microsomata, tiny granules of various nature em-
bedded in the protoplasm. Not a good term.

Microspores, the smaller or so-called male spores of
heterosporous plants: opposed to macrospores.

Midrib, the central or main vascular bundle of a leaf.

Monadelphous, when the stamens are all united
together by their filaments into a tube or column.

Monandria, the 1st class of the Linnean system. See
vol. ii. p. 288.

Moniliform, like a necklace or string of beads.

Monocarpellary, consisting of one carpel.

Monocotyledonous, having only a single cotyledon
or seed-leaf.

Moneecia, the 21st class of the Linnean system.
See vol. ii. p. 290.

Moneecious, having male and female flowers on the
same individual.

Monotypic, term used of genera which comprehend
but a single species, e.g. Welwitschia.

Morphology, that department of botanical study
which deals with the form of the plant-body,

including its development, the growth of its distinct
members, &c.

GLOSSARY,

Mother-plant, that parent of a hybrid upon which
the seed is matured.

Mycelium, the filamentous vegetative body of a
Fungus.

Myco-cecidium, a gall which owes its origin to the
attacks of Fungi.

Mycorhiza, a root invested by a fungal mantle:
supposed to be a case of symbiosis,

Mycosis, a diseased condition of animal tissues
alleged to be due to the presence of a Mould-fungus.

Myrmecophilous, used of plants which attract ants,
the latter often living altogether upon the plant
and affording it protection against certain enemies.

Nectary, a honey-secreting gland or part of a flower.

Neroli, Oil of, the ethereal oil yielded by the flowers
of the Orange-tree.

Neuter flowers, flowers destitute of functional
stamens or carpels.

Node, the part of a stem at which a leaf or whorl of
leaves is inserted.

Nodose, or Nodosus, knotty; having well-marked
nodes or knots.

Nodulated, having small knots: diminutive of nodose.

Nucellus, the central portion or body of an ovule,
containing the embryo-sac.

Nuclear plate, the assemblage of nuclear fibrils in
the equator of a nucleus during the division of the
latter.

Nucleus, (1) of starch-grain, same as hilum; (2) of
an ovule, an old term for nucellus; (3) the cell-
nucleus, a specialized portion of the protoplasm
of a cell exhibiting remarkable figures during divi-
sion and presiding over the chemical processes that
take place in the cell.

Nut, a hard, indehiscent, 1-seeded fruit resulting
from a polycarpellary ovary.

Nutation, spontaneous changes in position of growing
organs; a kind of oscillation or regular movement
in parts of plants.

Obovate, ovate with the broader end at the apex.

Omphalodium, the scar at the hilum of a seed.

Ontogeny, the history of the individual development
of an organized being.

Oogonium, the cell in which the female sexual cell
or cells are produced; especially amongst Thallo-
phytes.

Oophyte, that stage in the life-cycle of a plant which
bears the sexual organs.

Ooplasm, the substance of which the female sexual
cell consists. Not a good term.

Ooplast, the female sexual cell. Not a very good
term.

Oospore, a fertilized egg-cell.

Operculum, the lid of a Moss capsule.

Order, a division of plants intermediate between class
and genus, consisting usually of a group of genera
related to one another by structural characters
common to all. Same as family as used in this
book.

Orthostichies, vertical ranks of leaves.
p. 897.

Orthotropous, applied to an ovule with straight
nucellus wherein the micropyle is at a point far
removed from the funicle.

Osmosis, the tendency of fluids to pass through

Cf. vol. i.

919

porous membranes; the phenomena attending the
passage of fluids through porous membranes.

Ostiole, the aperture of the conceptacle in the
Fucacee.

Ovary, the part of the pistil that contains the ovules
or immature seeds; the closed chamber-like portion
of w single free carpel, or the many chambers of
several united carpels in which the ovules are
produced.

Ovule, in Phanerogams is the macrosporangium or
nucellus with its integuments, and containing the
embryo-sac. The ovule is the immature seed.

Ovuliferous scale, the ovule-bearing scale of Conifers.

Palzo-botany, Fossil botany.

Palate, a projection in the throat of a personate
corolla (or corolla such as that of the Snapdragon).
Palea, the inmost of the glumes which inclose the
individual flowers of Grasses; a chaffy scale or

chaff-like bract.

Palisade-cells, the green assimilating tissue, consist-
ing of cylindrical cells, usually found towards the
upper surface of the leaf-blade.

Palmate (of leaf-blades), lobed so that the projections
radiate from the point of insertion.

Panicle, a loose branched cluster of flowers.
applied very strictly.

Papilionaceous, like a butterfly: a term applied to
the corolla of a section of Leguminosae, including
the Pea and Bean, &c.

Papilla, a minute nipple-shaped projection.

Papillose, bearing papille.

Pappus, the hairy or feathery development of the
calyx of a Composite plant, which promotes dis-
persal by wind ; thistle-down or the like.

Parallelodromous. See vol. i. p. 634.

Paraphyses, sterile filaments accompanying the
sexual organs in Mosses, the asci and basidia of
Basidiomycetes, and in other cases.

Parasite, a plant which lives upon and obtains or-
ganic nutriment from the tissues of a living plant
(or animal).

Parastichies, secondary spirals in the arrangement
of leaves.

Parenchyma, usually thin-walled tissue consisting of
cubical or polygonal cells, and forming the pulp of
leaves, fruits, &c. ;

Parthenogenesis, the development of an egg-cell
into an embryo without fertilization taking place.

Parthenogonidia, certain reproductive cells in a
Volvox-colony which propagate the plant asexually.

Partite, cleft, but not quite tc the base.

Patelliform, disc-shaped; circular with a rim.

Pedate venation. See vol. i. p. 633.

Pedicel, an ultimate flower-stalk bearing a single
flower.

Pedunculus, or Peduncle, a general flower-stalk
bearing either a single flower or a closely-crowded
cluster of flowers.

Peltate, shield-like: said of leaves when the petiole is
attached to the under surface of the blade and not
to the margin.

Perfoliate, appearing as if perforated by a stem:
said where a stem is so embraced by a leaf that the
former seems to pass through the latter.

Perianth, the floral envelopes, consisting of calyx or
corolla, or both: used especially when it is not easy
to distinguish between them.

Not

920

Periblem, the embryonic tissue at 4 growing point
from which the primary cortex arises,

Pericarp, -ium, the wall of an ovary that is developed
into a fruit.

Perichaztium, the sheathing structures in Muscinee
which envelop the clusters of archegonia and an-
theridia.

Peridium, the outer envelope investing the fructifi-
cation in certain Fungi.

Perine, the outmost layer of sculpturing on the mem-
brane of pollen-grains.

Perisperm, the tissue of the nucellus, in which, some-
times, food material is stored for the ultimate use
of the embryo. It is external to the embryo-sac.
In many old systematic books it is used for all
food-material of seeds which is external to the em-
bryo.

Peristome, the ring of teeth around the mouth of a
Moss capsule.

Perithecium, the flask-shaped cavity in which asci
are produced in certain Fungi.

Petal, a corolla-leaf.

Petaloid, -ine, like a petal.

Petiole, the stalk of a leaf.

“Petit grain”, name for the ethereal oil yielded by
the leaves of the Orange-tree.

Phenology, that branch of botanical investigation
which deals with the recording, tabulation, and
comparison of the times and seasons at which plants
open their flowers and perform other periodic func-
tions in various portions of the globe.

Phanerogamia, seed-bearing or flowering plants.

Phloem, soft bast; the soft outer portion of a vascular
bundle, of which sieve-tubes are the most charac-
teristic constituents.

Phrygana, an old term for a growth of stiff and
prickly under-shrubs.

Phycocyanin, the blue pigment of the Cyanophycee
or lowest Algae.

Phycophzin, the brown pigment of the Brown
Alge.

Phycoerythrin, the purple colouring-matter of Red
Sea-weeds.

Phylloclade, a branch assuming form and function
of a foliage-leaf: same as cladode.

Phyllode, a petiole assuming the form and function
of a leaf-blade.

Phyllotaxis, leaf-arrangement; the arrangement or
order of distribution of leaves on the stem.

Phylogeny, or Phylogenesis, the history of the
genealogical development of an organized being;
the race history of an animal or plant, as distin-
guished from ontogeny, the history of individual
development.

Phylum, a main division of the vegetable kingdom.

Pileus, the cap-shaped receptacle of a Basidiomyce-
tous Fungus ; the umbrella-like part of a mushroom.

Pili fasciculati, tufted hairs,

Pili stellati, stellate hairs,

Pinnate, when leaflets are arranged on either side of
@ common rachis or petiole,

Pistil, the female organ of a flower, consisting of
ovary (style) and stigma; if the carpels are apocar-
pous there are many pistils; if syncarpous, only
one.

Pistillate, said of a plant or flower containing a
pistil; most correctly, of one having no stamens.

GLOSSARY,

Pitcher, a tubular or excavated leaf, usually contain-
ing a liquid; an ascidium.

Pith, the central cellular part of a stem or root.

Pits, thin places or depressions on cell-walls.

Placenta, the part of the carpel which bears the
ovules; in Vascular Cryptogams, the portion of leaf-
surface bearing the sporangia. j

Plaited, folded; folded into plaits lengthwise ; plicate.

Plant-formation, a term used to indicate the pre-
sence of two or more types of plant-community in-
termingled together, often in obvious strata. Cf.
vol, ii. p. 896.

Plasmodium, in the Myxomycetes; a mass of naked
multi-nucleate protoplasm exhibiting amceboid
movements,

Pleomorphism, the occurrence of more than one
independent form in the life-cycle of a species,
especially in Fungi and Bacteria.

Pleurocarpous, used of Mosses in which the arche-
gonia are borne, not at the tips of the main but of
secondary shoots.

Plicate, of zstivation; folded lengthwise in plaits.

Plumule, the rudimentary shoot of an embryo.

Pod. See Legume.

Podium, a term for the torus or floral receptacle.

Polar nuclei, the two nuclei—one from each end of
the embryo-sac of Angiosperms—which approach
one another and fuse to form the definitive nucleus
of the embryo-sac.

Pollarding, the act of removing the crown of a tree
so as to induce it to throw out branches around the
place of amputation.

Pollen, the mass of fecundating cells or grains con-
tained in the anther.

Pollen-grain, one of the fecundating cells of the
pollen; the microspore in flowering plants.

Pollen-sac, the sporangium in which the microspores
or pollen-grains of flowering plants are developed.

Pollen-tube, the tubular outgrowth of a pollen-grain
by means of which fertilization is achieved.

Pollinia, masses of coherent pollen-grains.

Polycarpellary, having or consisting of a number of
carpels,

Polychotomous, branching repeatedly into equiva-
lent portions.

Polyembryony, the production of more than a single
embryo in an ovule,

Polyhedra, angular bodies which arise from the
zoospores into which the zygote of Hydrodictyon
breaks up. Ordinary Hydrodictyon-nets arise in-
side them,

Porogamic, used of flowering plants in which the
pollen-tube effects an entrance to the ovule by the
micropyle.

Porous, used of dehiscence of anthers, &c., by means
of holes.

Prickle, a sharp-pointed process of the epidermis or
cortex, but destitute of vascular tissue.

Primordial utricle, that portion of the cell-protoplasm
which forms a bag in contact with the cell-wall.
An old name which has persisted in the terminology.

Procumbent, lying along the ground.

Prolepsis, something of the nature of an anticipation,
See vol. i. p. 8

Pro-mycelium, the limited tubular growth arising
from the chlamydospores in Hemibasidii and Uredi-
new, from which conidia are abstricted,

Prostrate, lying flat on the ground.

2 GLOSSARY,

Protandrous, Proterandrous, used of flowers when
the anthers dehisce before the stigmas are receptive.

Proteid, a nitrogenous substance of complex constitu-
tion, generally of a viscid nature and rarely crystal-
lizable. The proteids include albumin, globulin,
peptone, &c.

Prothallus, -ium, the structure produced by the ger-
mination of the spore of Ferns, bearing sexual organs,
and from which the young plant arises and derives
nourishment for a time; also the homologue of this
in flowering plants.

Protogynous, Proterogynous, used of flowers in
which the stigmas are receptive before the pollen of
the same flower is discharged.

Protonema, the filamentous growth of a Moss from
which the leafy shoots arise by budding.

Protoplasm, the living and formative organic sub-
stance of plants and animals; living matter in its
simplest form, serving as the basis of both animals
and plants, and consisting of carbon, oxygen, hy-
drogen, and nitrogen, colourless, transparent or
nearly so, and somewhat viscid in consistence.

Protoplast, the protoplasmic cell-body; a simple one-
celled organism. ©

Pseudo-hermaphrodite flowers are such as have
been functionally unisexual by the suppressing of
either stamens or carpels.

Pseudomorph, a term borrowed from mineralogy ;
an unusual or altered form. Cf. vol. i. p. 185.

Pulverulent, powdery.

Pulvinate, cushion-like.

Pulvinus, the enlargement of a petiole or leaf-stalk
at its point of insertion on the stem, or of a second-
ary petiole at its point of insertion on the leaf-rachis,

Pycnidium, in Fungi; a receptacle or cavity of vary-
ing form, in which conidia (pyeno-conidia) are pro-
duced: especially in Ascomycetes.

Pyrenoids, refractive bodies imbedded in the chloro-
phyll of many Green Algz.,

Race, a variety or form not distinguished by characters
important enough to rank as a species, but repro-
duced by seed and transmitting its characters to
the offspring; also loosely used for a group of allied
individuals without regard to rank.

Racemus, Raceme, an indefinite or centripetal
inflorescence with pedicellate flowers.

Rachis, the axis of a compound leaf, or of a spike or
other indefinite inflorescence.

Radical, belonging to or arising from a root, or from
a root-like portion of the stem below the ground,

Radices adligantes, clinging roots.

Radices columnares, columnar roots.

Radices fulcrantes, stilt-like roots.

Radices parietiformes, or tabular roots. See vol. i.
p. 754.

Radices tuberosz, or tuberous roots; roots beset
with tuber-like enlargements.

Radicle, the root of an embryo; usually not separ-
able from the hypocotyl.

Radix, the root.

’Raphe, that part of the stalk of an anatropous ovule
which is fused with the body of the ovule; in Dia-
toms, the median line on the frustule, possibly a
slit.

Receptacle, of a flower; the abbreviated or flattened
axis upon which the various floral members are
inserted,

921

Reniform, kidney-shaped.

Replum, the framework, or frame-like placenta,
which remains in Cruciferous and other fruits after
the valves have fallen away.

Resilient, springing back, rebounding: used of fruit-
stalks, stamens, &c.

Resin-duct, an intercellular passage into which
resin is secreted and where it is stored.

Respiration, the term applied to the absorption by a
plant of free oxygen from, and evolution of carbon
dioxide into the air. It is the outward sign of a
destructive oxidative process going on within the
plant, by means of which latent energy is rendered

available.

Revert, Reversion, a sudden return or breaking back
to an ancestral form.

Revolver-flowers. See vol. ii. p. 249.

Rhizoids, the hair-like filaments of Mosses and
Liverworts, which perform the functions of roots.
Rhizome, an underground (or prostrate) stem of
root-like appearance from which roots and her-

baceous stems arise.

Rhizomorph, name given to the curious vegetative
phase of Agaricus melleus, which resembles a root.

Rhizophore, a leafless branch of peculiar construc-
tion which, in Selaginella, arises at the place where
ordinary branching takes place, and bears roots at
its free end. .

Rhizotomoi, a guild of herbalists in ancient Greece,

Ring, Annual, the zone of wood formed from the
cambium in the course of one season in a Conifer or
Dicotyledon.

Ringent, gaping, as the mouth of a bilabiate corolla.

Ringing, the act of removing from a branch or trunk
a circular zone of bark right down to the wood.

Root-cap, the cellular cushion produced at the apex
or tip of a root.

Root-stock. Same as rhizome.

Rostellum, the morphological apex of the gynceceum
of an Orchid; usually a beak forming the boundary
between the stamen and stigma in Orchids.

Rosulate, collected in form of a rosette.

Rotate, wheel-shaped; circular and_ horizontally
spreading.

Runner, a prostrate filiform branch which is disposed
to root at the end or elsewhere.

Samara, an indehiscent winged fruit, as the key of
the Ash or Maple.

Saprophyte, a plant which grows on dead and de-
caying organic matter.

Scabrous, rough to the touch.

Scape, or Scapus, a peduncle rising from the ground.

Scarious, thin, dry, and membranaceous, and not
green.

Schizocarp, a polycarpellary fruit which breaks into
1-seeded portions.

Sclerotic-cell, a hard, thick-walled cell, often of
irregular form; sclerotic cells may be united to-
gether into layers, or isolated in soft parenchyma.

Sclerotium, in Fungi a tuber-like mass of hyphe,
which, after remaining dormant for a while, ulti-
mately sprouts, producing fructifications. In the
Myxomycetes it is the resting-stage of the plas-
modium.

Scorpioid cyme, a definite inflorescence rolled up
towards one side like a crook: common in Boragi-
nacez.

922

Scutellum, the sucker or cotyledon of a Grass embryo.

Scutiform, having the form of a shield.

Seed, the fertilized and matured ovule.

Seed-coat, the integument of the seed, formed from
the investment or investments of the ovule.

Seedling, a young plant raised from a seed.

Semifrutex, or Semi-shrub, a shrub the shoots of
which become woody at the base only, this portion
alone being perennial.

Sepal, a leaf-member of the calyx.

Sepaloid, resembling a sepal.

Separation-layer. See Absciss-layer.

Septum, a partition; a thin wall separating compart-
ments.

Sericeus, silky ; clothed with soft straight hairs.

Serrate, of leaf-margins; beset with teeth pointing
towards the apex.

Sessile, destitute of stalk, petiole, or pedicel.

Seta, a bristle; the stalk of the spore-capsule in a
Moss or Liverwort.

Shoot, that portion of the plant which is differenti-
ated into stem and leaves and bears the reproductive
organs.

Sieve-cells, cells which have pores in their walls
causing a sieve-like appearance ; sieve-tubes.

Sieve-plates, areas in the walls of sieve-cells or
sieve-tubes perforated by pores.

Sieve-tube, an articulated tube whose contiguous
elements communicate by means of open pores
aggregated together upon sieve-plates. The sieve-
tube is the characteristic element of the phloem.

Siliqua, the fruit of a Cruciferous plant, a longish
pod or seed-vessel. Cf. vol. ii. p. 432.

Sinistrorse, used of twining stems which turn from
north through west to south, &c.: the opposite of
dextrorse.

Sinuous, Sinuate, used of a leaf-margin which is
strongly indented in a wavy manner.

Sling-fruit, a general term given to any fruit which,
in virtue of the possession of contractile tissues,
throws its seeds to a distance, or is itself so thrown.

Soboles, a thin creeping stem, often subterranean.

Soredium, the ‘brood-body’ or ‘brood-bud’ of a
Lichen, consisting of a few algal cells wrapt round
with a weft of fungal hyphe.

Sorus, a cluster of sporangia, such as those of Ferns.

Spadiciform, like a spadix.

Spadix, a fleshy spike.

Spathe, a large bract-like sheath inclosing an inflores-
cence.

Spatulate, like a spatula, oblong with the lower end
attenuated.

Species. Under this term may be included all indi-
viduals which possess in common such a number of
characters that they may be regarded as being
descended from a common ancestral form.

Spermatium, a male sexual cell which becomes free,
but is unprovided with special organs of locomotion.

ae ia the protoplasm of the male sexual
cell.

Spermatoplast, a male sexual cell.

Spermatozoid, a free-swimming male sexual cell
provided with cilia as organs of locomotion.

Spike, an indefinite inflorescence with flowers sessile
on an elongated axis.

Spine, a sharp-pointed body possessing vascular
tissue, commonly a branch or some portion of a leaf.

GLOSSARY,

Sporangiole, in the Fungi; a small sporangium,
usually containing few spores, and larger many-
spored sporangia being also present.

Sporangiophore, that which bears sporangia; a scale
bearing sporangia in Equisetum.

Sporangium, a sac within which spores are deve-
loped.

Spore, a reproductive cell which becomes free, and is
capable of developing into a new individual.

Sporidium, a spore abjointed from a pro-mycelium.

Sporocarp, a fructification, often the result of a
sexual act, in which spores are produced, as in Red
Sea-weeds and Fungi. Also used of the sporangial

receptacles of the Hydropteride.

Sporogonium, in Mosses; the so-called ‘moss-fruit’
with its appendages, consisting mainly of the capsule
and seta or stalk.

Sporophyte, that stage in the life-cycle of a plant
which bears the spores. Cf. Oophyte.

Spur, an excavated slender continuation of some
portion of a flower, usually containing nectar.

Squamiform, scale-like.

Squamigerous, furnished with scales.

Stamen, the male organ in a flower, which produces
pollen. It consists of the filament or stalk, and the
anther, in which the pollen is contained and which
is supported by the filament. The stamens collec-
tively form the andreecium.

Staminate, having stamens.

Staminiferous, bearing stamens.

Staminode, a sterile stamen.

Standard, in papilionaceous flowers, is the unpaired,
posterior petal.

Sterigma, the tube or stalk-like branch from which
conidia are abstricted. :

Stigma, that portion of the pistil which receives the
pollen.

eva paired foliaceous appendages of the leaf-

ase.

Stirps cirrhosa, a tendril-bearing stem.

pas clathrans, a lattice-forming stem. See vol. i.
p. 678.

Stirps fluctuans, a floating stem.

Stirps humifusa, a prostrate stem.

Stirps palaris, a standard-stem, ¢.c. an erect, un-
branched stem.

Stirps plectens, a weaving stem. See vol. i. p. 671.

Stirps radicans, a stem which climbs by means of
roots.

Stirps volubilis, a twining stem.

ae the parent forms from which a hybrid is de-
rived.

Stolon, or Stolo, a procumbent stem which bears
buds which take root; the buds are more frequent
and the internodes shorter than in the runner.

Stoma, an intercellular space or pore in the epider-
mis which, bounded by adjustible guard-cells, forms
the means of communication between the lacune of
the plant and the outside air.

Stratification, the layering of cell-walls or starch-
grains.

Stroma-starch, in certain Alge (e.g. Hydrodictyon),
the fine-grained starch deposited throughout the
chlorophyll-body, which plays a different part in the
economy of the plant from that deposited around
the pyrenoid. Cf. vol. ii. p. 640.

Style, the usually attenuated prolongation of an ovary
upon which the stigma is borne.

GLOSSARY.

Sub-capitulum, a secondary capitulum.

Suberin, a corky substance; the substance or group
of substances present in cuticularized or corky cell-
walls

Subex, a stem bearing scale-leaves.

Succulent, fleshy, pulpy.

Sucker. See Surculus.

Suffrutex, an under-shrub; a woody plant of quite
humble growth.

Suffruticose, somewhat shrubby.

Surculus, or Sucker, a shoot arising from a sub-
terranean base.

Suspensor, in Flowering Plants and in Selaginella;
the filament of cells at the lower extremity of which
the embryo arises.

Suture, a line of union, very frequently the line along
which dehiscence also takes place.

Swarm, a social aggregate of simple organisms which
live together but are not attached to any substratum,

Swarm-spore, a motile, ciliated, asexual reproductive
cell destitute of a cell-membrane.

Switch-plant, a plant with reduced or wanting
leaves, the shoots of which are green and subserve
the functions of leaves.

Symbiosis, the association of two organisms which
live together in intimate connection, both contri-
buting to their mutual welfare.

Syncarpous, said when the carpels of a gynceeceum
are united.

Synconium, the fleshy excavated inflorescence of «
Fig.

Synergidz, two naked cells situated at the micro-
pylar end of the embryo-sac, and assisting in the
passage of the male cell to the egg in porogamic
fertilization.

Syngenesia, the 19th class of the Linnean system.

Syngenesious, having coherent anthers.

Systole, the rhythmic contraction of a contractile
vacuole.

Tagmata, aggregates of micelle.

Tapetal cells, the layer of cells immediately external
to the archesporium, and becoming latterly dis-
organized with the maturing of the spores (or
pollen-grains).

Teleutospore, in Uredinee, a resting-spore which on
germinating gives rise to a pro-mycelium or basi-
dium.

Tenaculum, the clasping, rosette-like clamps of
Struvea, by means of which independent branches
are held together.

Tendril, a filamentous branched or unbranched organ,
usually sensitive to contact, by means of which a
plant climbs.

Tentacle, an irritable hair or emergence on a leaf,
as in Dionza, Drosera, &c.

Terete, round, «.e. circular in transverse section.

Ternary hybrid, the plant resulting from crossing a
hybrid with « species different from either of its
parent forms.

Ternate, used of compound leaves with three leaflets,
one terminal and two lateral.

Testa, the integument of a seed, often arising from
the outer of the two ovular coats.

Tetrad, a group of four cells (e.g. spores, pollen-grains),
usually arranged in the four corners of a 4-sided
pyramid (tetrahedon).

923

Tetradynamia, the 15th class of the Linnean sys-

em.

Tetradynamous, used of stamens when there are
six, of which four are longer than the other two—
as in Cruciferee,

Tetraspores, the asexual spores of Red Sea-weeds,
usually aggregated in clusters of four.

Thalamus, the floral receptacle.

Thallidium, » vegetative reproductive body, espe-
cially amongst Thallophytes and Muscinee.

Thallus, a vegetative body without differentiation
into stem and leaf.

Thermal constants of vegetation. See vol. i.
p. 557.

Tissue, a continuous aggregate of cells having «
common origin,

Tomentose, felty or invested in tomentum.

Tomentum, dense matted investment of woolly
hairs.

Torus, (1) the floral receptacle; (2) the thickening
on the pit-closing membrane of a bordered pit.

Trabecule, folds or ridges projecting into a cell from
the wall; the term also given to strings of fila-
mentous cells bridging intercellular spaces.

Tracheids, elongated, poiated, and more or less
lignified cells occurring in wood.

Transpiration, the act of exhaling aqueous vapour
from foliage or other portions of plants.

Trichoblasts, fusiform hard-walled cells. Not a
good term.

Trichogyne, the filamentous portion of the female
sexual apparatus of a Red Sea-weed, which receives
the spermatia.

Trichome, a hair-like or similar outgrowth of the
epidermis.

Truncate, appearing as if cut short at the tip.

Trunk, a main stem.

Tuber, a subterranean, somewhat fleshy shoot.

Tubercle, a small excrescence.

Tumescent, becoming enlarged, distended.

Turgescence, Turgidity, the state of tension set
up within a cell owing to the pressure of the osmo-
tic cell-contents upon the elastic cell-wall.

Turion, a subterranean budding shoot, especially in
perennials,

Umbel, an inflorescence in which a cluster of flower-
stalks arises all from the same point.

Unguiculate, narrowed at the base into a claw:
used of petals.

Urceolate, hollow and contracted at or below the
mouth like an urn.

Uredospore. See vol. ii. p. 686.

Utricle, an archaic term for a parenchyma-cell.

Vacuole, a cavity in the protoplasm containing cell-
sap.

Vagina, the sheathing portion of a leaf-base.

Valvate, having valves; opening by valves; also,
used of the arrangement of the parts of a flower-
bud when they just meet but do not overlap. Cf.
vol. ii. p. 210.

Valve, (1) in flowering plants, the pieces into which
a capsule breaks are termed valves; also the mov-
able flaps in the dehiscence of anthers; (2) in Dia-
toms, the valves are the halves of the silicified
membrane or shell, also called frustules.

924

Variegation, a term employed to designate the dis-
position of two or more colours in the petals, leaves,
and other parts of plants.

Vascular bundle, a continuous strand of vascular
tissue, consisting either of xylem or phloem, or
of both. Not infrequently sclerenchymatous ele-
ments are associated with the bundle, when it is
termed a fibro-vascular bundle.

Vascular elements, cells or vessels whose main
function is the distribution of water or formed
food-substances. The chief of them are the vessels
and tracheids of the wood, and the sieve-tubes of
the phloem.

Velum, in Isoétes; the indusium-like membrane
which covers the sporangium.

Velum partiale, in Hymenomycetes; the veil
stretching from the stipe to the edge of the pileus.
It often remains as the annulus.

Velum universale, in Hymenomycetes; the mem-
branous wrapper inclosing the whole fructification.

Venation, the arrangement or pattern of the vascular
bundles in a leaf.

Ventral canal-cell, the small cell which is cut off
from the central cell of an archegonium immediately
below the neck.

Ventricose, unequally swollen.

Vernation, the arrangement of the parts in the bud,
especially a vegetative bud.

Verrucose, covered with warts.

Versatile, turning freely on its support.

Verticillate, arranged in a whorl.

Vessel, a tube consisting of cells which have be-
come confluent by the partial or complete absorption

GLOSSARY.

of the intervening walls, They are common in the

wood of Angiosperms.
Viviparous, term applied to plants the seeds of
which germinate whilst still on the parent plant.

Volva, same as velwm universale.

Whorl, a series of appendages arranged in a circle
around an axis.

Witches’ Broom, a form of gall found on the Silver
Fir and other Conifers; sometimes applied to the
bird’s-nest-like hypertrophies on the Birch, &c.

Wood, the hard, lignified portion of the vascular
tissue otherwise known as the xylem. It contains
tracheids, woody fibres, and wood parenchyma,
though not all of these are necessarily found in the
wood of any given plant.

Xenogamy, pollination between flowers growing on
different individuals of the same species.

Xylem, the woody portion of vascular tissue. See
Wood.

Zoogleea, a solid gelatinous colony of Bacterial
organisms.

Zygomorphic, applied to flowers which are symmet-
rical about one plane only, or can be cut into similar
halves in only one plane.

Zygospore, a spore formed by the union of two
gametes.

Zygote, a general term for the product of fusion of
two gametes.

Zygozoospore, the motile stage of a zygote, the
product of fusion of two motile gametes.

INDEX.

The page numbers in bold type indicate illustrations.

Abano, Spheerotilus in hot springs at, i, 554.

Abele. See Populus alba.

Abies, and Witches’ Broom, ii. 526.

— axillary buds, ii. 29.

— fertilization, ii. 420.

— green cotyledons, ii, 622.

— needles, ii. 725.

— pollen storing and dispersion, ii. 145,

— protection of ovules, ii. 72.

Abies excelsa and galls of Chermes abietis,
ii, 544,

— — cone characteristics, ii. 725.

— — egg-cells, ii. 419.

— — embryo development, ii. 438.

— — flower-opening constant, i. 559.

— — Pine-apple Gall on twigs, ii. 534.

— — stamen, ii. 87.

—— various dimensions, i. 722.

— — vertical range, i. 527.

Abies orientalis, cotyledons, i. 621.

Abies pectinata, i. '717.

——and Acidium elatinum, ii. 523, 527.

—-— annual rings and sinkers of Mistletoe,
i, 210.

—— bract scale, ii. 440, 441, 721.

—— cone, ii. 441, 721, 725.

—— embryo development, ii. 438.

— — ovuliferous scales, ii. 441.

Abietiness, arrangement of scales, ii. 440.

— distinguishing feature, ii. 721.

— embryo development, ii. 438.

Abronia, unequal cotyledons, i. 622.

Absorbent cells, i. 765.

— — of cotyledons, i. 599, 600.

Absorption bands of chlorophyll spectrum, i.

372

Absorption-cells, i. 87, 217.

——capitate or glandular, of multicellular
hairs, mode of action, i. 229.

— — controlling influences, i. 90.

— — form of, i. 86.

—— fungal hyph a substitute for, i. 249.

——§in Leucobryum, &c., i. 86.

— — in Nepenthes pitcher, i. 135.

— — in special cavities and grooves in leaves,
i, 230.

— — of Bartsia, i. 180.

— — of Cuscuta, of Cassythe, i. 176.

—— of foliage-leaves, other than trichomes,
restricted action, i. 230.

— — of Lathrea, i. 182.

— — of leaves, conditions of action, i. 227.

— — of Mildews, i. 166.

—— of Orchid aérial roots, i. 223.

— — of Plagiothecium, i. 85.

— — of Rhinanthacer, i. 178.

— — of roots, permeability, &c., i. 226.

— — of Saprophytes, i. 114.

— — of Stellaria media, i. 228.

—— of Thesium, i. 177.

—— of Utricularia bladders, i. 121.

— — of water-receptacles, proof of acting as
such, i, 240.

— — on leaf-cuttings, ii. 42.

— — on leaves of Tamarisks, Frankenias, &c.,
mode of development, i. 236.

— — position of, i. 88.

—-— replaced by mycelium, i. 91.

——shape in relation to food-supply, &c.,
i, 90.

Absorption of food-salts, i. 85.

— of rain and dew, by foliage-leaves, i, 225.

— of water by foliage-leaves, i. 232.

Absorption-roots, of Saprophytes, i. 115.

Absorptive cavities and cups on foliage-
leaves, i. 233.

— organs, of some Plumbaginew, i. 234.

par aaa Arabia, shade temperature, i.
556.

Abutilon Avicenne, autogamy, ii, 355.

— — cross-fertilization, ii. 304.

Acacia. See also Robinia Pseud

Acaulescent Violas, cleistogamy, ii. 393.

Accessory organs, of flowers, ii. 71.

— substances, of plants, i. 460.

Acer and Gleditschia triacanthos, struggle for
existence, ii. 515.

— and Nectria, ii. 678.

—ar t of foliage-leaves, i. 92.

— colour of fiowers and flies, ii. 197.

— from chalk, ii. 613,

— green cotyledons, i. 622.

— hybrids in, ii. 584.

_ h 1 tissue arrar

t, i. 729.

— pollen-chambers, ii. 90.
— popularly so called, i. 534.
— reception of insects, ii. 230.
— root-slips, ii. 28.
— scent, ii. 201,
— true, diurnal positions of leaves, i. 534.
— unprotected pollen, ii. 107.
Acacia caffra, &c., hosts of Sarcophyte, i.
196.
Acacia lophantha, Australia, leaf, diurnal
positions, i. 534.
Acacia spadicigera, myrmecophilous, ii. 233.
Acacia spherocephala, myrmecophilous, ii.
233.
Acacias, Australian, coloured stamen fila
ments in, ii. 183.
— — distribution of stomata on phyllodes, i.
281.
— — leaf metamorphoses, i. 637.
— — phyllodes, i. 335.
— — wax on leaves, &c., i. 292, 312.
Acalypha, stamen, ii. 87.
Acanthacee, ii. 771.
— and cold, i. 545.
— inflorescence, i. 746.
— pollen-sprinkling apparatus in, ii. 271.
— scarlet flowers in, ii. 196.
Acantholimon, absorptive organs, i. 234.
— acicular leaves, i. 434, 437.
—and spiny Tragacanth-shrubs, Persian
steppes, i. 435.
— calcareous incrustation, i. 237.
— habitat, i. 235.
Acantholimon Senganense, absorptive or-
gans, &c., i. 235.
— — leaf, and section of part, i. 233.
—— lime incrustations, i. 235.
Acanthophyllum, leaves, i. 434.
Acanthus, and insect visits, ii. 223.
— colour-contrast in flower, ii. 191.
— cross-fertilization, ii. 304.
— emerging of leaves from soil, i. 639.
— honey protection, ii. 241.
— pollen-sprinkling apparatus, ii. 273.
— protection of pollen from wet, ii. 110.
Acanthus longifolius, flower, and pollen-
sprinkling apparatus, ii. 273.
Acanthus mollis, habit, ii. 772.
— — mildew of, i. 166.
— — seed-dispersal, ii. 833, 835.
Acanthus spinosissimus, i. 437.
Acanthus spinosus, pollen-sprinkling, ii. 273.
Acanthus spinulosus, hybrid of A. mollis x A.
spinosissimus, ii. 586,
Acarina, i. 138.
Acarospora glaucocarpa, habitat, i. 117.
Acarus, prey of Utricularia montana, i. 123.
Acaulescent Gentians, autogamy, ii. 387.

— roots, i. 753.

— texture of so-called mite-galls, ii, 532.
— vernation, i. 350.

Acer campestre, mite-galls, ii. 529.

Acer Monspessulanum, seed-dispersal, ii-
Acer platanoides, distribution of sexes, ii.

— — flower-opening constant, i. 559.

— — leafy twig, i. 416.

— — normal and sucker leaves, ii. 516.

— — seedling, i. 9.

——twig and elongation of leaf-stalks, i.

419.

— — venation, i. 631.

Acer Pseudo-platanus, distribution of sexes,
ii. 297.

—— imperfect flowers, ii. 295.

Acer rubrum, i. 488.

Aceras and Orchis, hybridization, ii. 583.

Aceros, of Braun, ii. 605.

Acetabularia, colonies, i. 585.

— marine lime accumulators, i. 261.

Acetabularia mediterranea, structure, &c.
ii. 646.

Acetabulariz, differentiation of thallus, it
646.

Acetic acid, from alcohol, i. 506.

Achene, embryo protection, ii. 450.

— nature of, ii, 429,

— of Gnaphalium alpinum, ii. 84.

Achenes, with pappus, ii. 432.

Achillea, hybrids, ii. 585.

— peripheral flowers, ii. 187.

Achillea Clavenne, habitat and hairiness, i.
316.

Achillea Millefolium, anthocyanin, i. 522.

—— gall-mites and flower metamorphosis,

ii. 548.

Achillea ochroleuca, i. Pl. VI.

Achimenes, ternary hybridization, ii. 560

Achlya, asexual zoospores, ii. 480.

— fruit, &., ii. 480.

— host for Saprolegniaceze and Chytridez, i.
170.

Achlya lignicola, sexual organs, ii. 671.

Achlya prolifera, on flies and fishes, i. 105.

— — sporangia, &c., ii. 17.

— — swarm-spore formation, ii. 669.

Achlya racemosa, host of Rhizidiomyces.
apophysatus, i. 170.

Achorion Scheenleinii, cause of ringworm,
i. 168.

Acid, acetic, from alcohol, i. 506,

— butyric, i. 463; ii. 623.

— caproic, ii. 202.

—carbonic. See also Carbonic acid.

—— dissociation by symbiotic Algz, i. 254.

926

Acid, carbonic, excretion by hyphe of Lichen,
action on calcium carbonate, i. 257.

— citric, i. 135, 463,

— formic, i. 135, 441, 463; ii. 233.

— gallic, from tannin, i. 507.

— humic, produced by decay, i. 101.

— in Dionza digestive secretion, i. 150.

— in secretion of Drosera glands, i. 144,

— — of Drosophyllum glands, i. 154.

— — of Pinguicula glands, i. 142.

— lactic, from milk, i. 506.

— malic, i. 135, 463.

—nitric, i. 64, 83, 263, 458,

— nitrous, i. 263.

— cnanthie, ii. 202.

— oxalic, i. 67, 458, 463.

— pelargonic, ii. 202.

— phosphoric, ferment action, i. 465.

— prussic, i, 462.

— silicic, occurrence in plants, i. 67, 261.

—— in Diatom frustules though no trace in

aqueous habitat, i. 70.

— sulphuric, reduction, i. 458.

— valerianic, ii. 202,

Acids, fatty, nature of, i. 463,

— humous, and preservation of fossil plants,
i, 262; ii. 612.

— organic, function, i. 463.

— volatile fatty, i. 263.

— water incorporated in, i. 216.

Aconitum, and field-mice, i. 763.

— and humble-bees, ii. 239,

— cross-fertilization, ii. 304.

— downward pull of roots, i. 767.

— follicles, ii. 430.

— hybrids in, ii. 584.

— insects and pollen, ii. 245,

—leaf-buds, emergence from soil, i. 639.

— nectaries, ii. 179.

— odourless, i. 431.

— pollen-sacs, ii. 89.

— protandrous, ii. 311.

— protection of pollen from wet, ii. 110,

— trabecule in green cells, i. 374,

Aconitum Napellus, i. 450.

—— colour of sepals, ii. 183.

— — gertination, i. 622.

— — stamen, ii. 87.

Aconitum paniculatum, temperature within
flower, i. 501.

Aconitum variegatum, re-erection of inflo-
rescence, i. 744.

Aconitum Vulparia, buds, emergence from
soil, i. 639.

Acorus Calamus, absorptive cells of, i. 91.

—- — fertility, dependence on insects, ii. 402.

— — native place, ii. 402.

— — rhizome, ii. 745.

Acotyledones, of de Jussieu, ii. 602.

Acramphibrya, of Endlicher, ii. 604.

Acrocarpous, applied to Mosses, ii. 703.

Acrocomia sclerocarpa, and Clusia alba, i.
680.

Acrodromous venation, i. 632, 633.

Acrostichez, sporangia, ii. 706.

Acrostichum, distribution of sporangia, ii.
706.

Acrostichum sphenopnyllum, venation, i. 635,

Actza, coloured stamen-filaments, ii. 183.

Actza spicata, filament of stamen, ii. 88.

— — protogynous, ii. 310.

— — stamen, ii. 87.

Actinomorphic symmetry, ii 229,

Aculei, i. 433, 439.

Adam, and reputed egraft-hybrid of Cytisus,
ii. 570,

Adansonia, flower, monadelphia, ii. 292.

— hermaphrodite, ii. 296.

Adansonia digitata, age, i. 720,

— — dimensions, i. 722.

Adaptation in plants, i. 567.

— to light intensity, i. 394,

Adaptations, theory of, ii. 596.

Adaptive mechanisms subserve several pur-
poses, ii. 128,

Adder’sTongue. See Ophioglossum vuigatum.

Adenium Hongdel, seed dispersal, ii. 857.

INDEX,

Adenocarpus decorticans, &c., fruit protec-
tion, ii. 447.

Adenostyles, autogamy, ii. 363,

Adenostyles alpina, re-erection of inflo-
rescence, ii. 744,

Adenostyles Cacalize, offshoot formation, ii.
454,

Adherent fruits, ii. 867.

Adhesion, i. 58.

Adhesive disc, of tendril, i. 699.

Adiantum, cilia of spermatozoid, i. 29.

Adiantum arcuatum, venation, i. 635.

Adiantum Capillus-veneris, indusium, ii. 706.

Adinide, group of Dinoflagellata, ii. 625.

Adonis, foliage and light, i. 412,

— nectarless, ii. 167.

— protogynous, ii. 311.

Adonis eestivalis, colour-contrast in flower,
ii, 189.

— — effect of dry soil, ii. 500.

— — persistent cotyledons, i. 622.

—— scentless, ii. 209.

Adonis flammea, colour-contrast in flowers,
ii. 189.

— — effect of dry soil, ii. 500.

—— scentless, ii. 209.

Adovis vernalis, autogamy, ii. 381, 382.

— — protection of pollen, ii. 120,

— — protogynous, ii. 310.

Adoxa, dehiscence of pollen-sacs, ii. 92,

— honey, ii. 173.

— pollen-sacs, ii. 89.

Adoxa Moschatellina, autogamy, ii. 335.

—— scale-leaves of epicotyl, i. 624.

— — subex of plumule, i. 651.

Adventitious bud, development, ij, 26.

— buds of Mistletoe, i. 209.

— root, i, 751.

— shoot of Loranthus Europzeus, i. 213.

Aichmea, honey-concealment, ii. 180.

— protective water receptacles, ii. 234,

Echmea paniculata, ii. 733.

Ecidiomycetes, ii. 606.

Aicidium fruit, ii. 686,

— of rust-fungus, ii, 522,

— stage of Gymnosporangium, ii. 522,

A®cidium berberidis, ii. 686.

AKcidium elatinum causing Witches’ Broom
on Abies pectinata, ii. 526.

AXcidium Magelhenicum and Berberis vul-
garis, ii. 527.

®gilops ovata and Triticum sativum, hybrid
of, ii. 583.

—— creeping fruits, ii. 843, 844.

Aigilops ventricosa, creeping fruits, ii. 843,
844.

Afgopodium, how protected, i. 451.

4Hgopodium Podagraria, farmers’ enemy, ii.
798.

Aérial roots, i. 752.

—— buds on, ii. 28.

—— of Aroides, ii. 745,

— — of Orchidew, i. 221.

Aerides, sugar crystals in honey, i. 172.

4®schynanthus speciosus, plumed seeds, ii.
858.

4Eschynomene glabrata, seed-dispersal, ii.
853.

##schynoniene Indica, and rain, i. 537.

— — sensitiveness, i. 535,

Afsculinee of Braun, ii. 605.

Aisculus and Nectria, ii. 678.

— arrangement of foliage-leaves, i. 92.

— cotyledons, i. 608.

— curvature of branches, i. 416,

— deciduous bud-scales, i, 626.

— flowers, sexual conditions, ii. 295, 296.

— roots, i. 753.

— stamens as insect platform, ii. 225.

Aisculus discolor, &c., branching, i. 749.

4isculus Hippocastanum and gall-mites, ii.

529.

— — deciduous protective woolly hairs, i. 354,
— — flower, heptandria, ii. 289.

— — leaf-fall, i. 361, 560.

— —scent, ii. 200.

— — separation layers, i. 360,

ZAsculus Hippocastanum, thermal constants,
j. 559.
— — unfolding leaves, i. 351.
Higculus macrostachya, coloured stamen-
filaments, ii. 123. .
ZEsculus neglecta, bud-scales, i. 626.
ZEstivation, sorts af, ii. 210.
‘Aithionema, colour-contrast in inflorescence,
ii. 192.
Athusa, protogynous, ii. 311.
ZEthusa Cynapium, autogamy, ii. 342, 344.
Bthusa segetalis, autogamy, ii. 344.
Affinity, chemical, i. 58,
— selective, extreme cases of, i. 71.
Africa, poverty in Balanophorez, i. 196.
Agardh, ii. 603.
Agaricinez, Brazilian, luminosity, i. 502.
— edible forms, ii. 689.
— structure and characteristics, ii. 689.
Agaricus, basidial layer, ii. 684.
— latex, i. 470.
— spore-formation, ii. 20.
Agaricus campestris, edible, ii. 689.
Agaricus Gardneri, &c., luminosity, i. 502.
Agaricus melleus, sclerotia, ii. 689.
Agaricus muscarius, Pl. XIV., ii. 689.
— — appearance, ii. 491.
—— respiratory heat, i. 498.
Agaricus vellereus, raising power, i. 514.
Agarum Gmelini, ii. 662.
Agate, construction through plants, i. 261.
Agathis, ii. 721.
Agave, ii. 734.
— contractile layers of
— leaf point, i. 438.
— Mexican uplands, i. 657.
Agave Americana, i. 658, 746.
— — flowering, i. 745.
—— sap extrusion, “pulque”, i, 272.
Age of trees, i. 720.
Aggregate fruits, ii. 436.
Aggregation in cell-contents of Drosera leaf,
i. 148.
Agrimonia, anther, ii. 90.
— fruit, ii. 343, 434.
Agrimonia Eupatoria, autogamy, ii. 343, 344.
—-— duration of flowering, ii. 213,
— — flower, ii. 779.
—— flower, dodecandria, ii. 293.
— — hermaphrodite, ii. 296.
— — persistent receptacle, ii. 435.
Agrimonia cdorata, hooked fruit, ii. 873.
Agropyrum, pollination, ii. 142.
Agropyrum repens, boring runners, i. 516.
Agrostemma Githago, i. 491.
— — absorbent cells, i. 600.
— — autogamy, ii. 336.
— — cotyledons, i. 610, 622,
— — course of pollen-tubes, ii. 410.
— — effect of dry soil, ii. 500.
— — elevation and coloration, ii. 511.
— — germinating seed, i. 599.
— — light and growth, ii. 508.
— — movements of cotyledons, i. 532.
—— pollen-grain, ii. 100.
— — seed fixation, i. 616.
Agrostis, pollination, ii. 142.
Agrostis alpina, habitat, i. 112.
Agrostis stolonifera, &c., adaptability, ii. 513.
— — habit and habitat, ii, 502.
Agrotis and Habenaria bifolia, ii, 256.
Ailanthus, flower, ii. '778.
— scent, ii. 200,
Ail: 1 glandul
i. 484.
— — dimensions, i. 722.
-- — fruit, ii, 428, 430.
— — radical shoots, fi. 27.
— — seed-dispersal, ii. 853.
— — separation layers, i. 360.
Air, dust in, i. 79.
— loss of constituents through plants not
directly observable, i. 258.
— moisture of, and size of leaves, i. 287.
Aira alpina, bulbils, ii. 454,
Aira ceespitosa, anthocyanin in glumes, i, 522.
— — pollination, ii. 142.

th

ii, 94

antho in buds,

Aira flexuosa, pollination, ii, 142.
Air-bladders of Macrocystis, ii. 633,
Air-chambers of Marchantia, ii. 697.
Air-spaces in aquatic plants, i. 424,

—— of mesophyll, i. 279.

Aizoon, group of Saxifrages, i. 233.
Aizoonia, antogamy, ii, 337,

Ajuga, ii. 40.

— hybrids, ii. 585.

a tae facultative perennial, ii.

Ajuga reptans, stolons, i. 663.

— — vitality of spermatoplasm, ii, 96.

Akebia quinata, Japan, nutation, i. 683.

Akinetes, of Chlorophycew, ii. 628.

— of Pleurococcus, ii. 636.

Albizzia, pollen-chambers, ii. 90.

Albuca, cross-fertilization, ii. 301.

— nectaries, ii. 175.

Albuca minor, pollen-grains, ii, 98,

Albumen, formation, i. 458.

— of seed, nature of, ii. 421.

— osmotic behaviour of, i. 59.

Albumens, coagulation, i. 553,

— composition, i. 457.

— decomposition and reconstruction, i. 464.

— putrefactive decomposition, i. 506,

— soluble and insoluble, i. 458.

Albuminoids, i. 72.

Albuminous, applied to seed, ii. 421.

— substances, conducting tissues for, i. 480.

Albumins, and respiration, i. 495.

Alchemilla, absorption of water collected in-
considerable, i. 240.

— dehiscence of pollen-sacs, ii. 92.

— honey, ii. 173.

— protection of pollen, ii. 124, 125.

Alchemilla vulgaris, i. 228.

—— and animals, i. 432,

— — autogamy, ii. 350.

—— effect of Uromyces Alchemilla, ii. 524,

—— unfolding leaves, i. 349.

—— vernation, i. 349.

Alcohol, production, i. 506.

Alder. See Alnus.

— Alpine. See Alnus viridis.

—gray. See Alnus incana.

Aldrovandia, i. 148.

— dispersal of offshoots, ii. 807.

— distribution, habitat, description, &., i.
151, 152, 153.

— floating habit, i. 668.

— pollen dispersion, ii. 105.

— trap mechanism, i. 150.

Aleochara and indoloid scents, ii. 207.

Aleochara fuscipes, and Dracunculus Creti-
cus, ii. 165.

Aleppo Pine. See Pinus halepensis.

Aleurone grains, i. 42, 457, 458.

Aleutians and fish-lines of Nereocystis, ii.
663.

Alfredia, absorption cells of hairs, i. 227.

Alfredia cernua, i. 97.

—— practical demonstration of irrigation,

i. 96.

Alge, and heat, i, 554.

— calcareous, marine, reef-forming, i. 261.

— dispersal, i. 246.

— distribution in lichen-thallus, i. 244; ii. 694,

— division of Thallophyta, ii. 604.

— partners in lichen-thallus, 1. 246.

— proper application of term, i. 246.

— sapropbytic, food-absorption, i. 113

— symbiosis with animals, i. 254,

— symbiosis with lichens, ii. 691.

Algeria, thistles, i. 438.

Alhagi Kirgisorum, spines, i. 443.

Alighting-platforms for insects, ii. 225.

Alimentary canal, seeds passed through, ii.
862.

Alisma, no special arrangement for rain-
water conduction, i. 98.

— protective isolation by water, ii. 234.

Alisma natans, sub-aqueous fertilization, ii.
391.

Alismacez, floral characters, &., ii. 739.

Alkalies, i. 83,

INDEX,

mee protective, of Atropa Belladonna,
i, 431,

Alkaloids, function, i. 462.

— poisonous, in roots, i, 763.

Alliance, subdivision of class, ii, 617,

Alliances, of Braun, ii. 605.

Alliaria, nectary, ii. 175,

Allioidez, characteristics, ii. 731.

Allionia, cross-fertilization, ii. 304.

— nectaries, ii. 177.

Allionia violacea, autogamy, ii. 357.

— — opening and closing, ii, 212.

Allium, cotyledon in germination, i. 606.

— epiphyllous buds, ii, 43.

— polyembryony, ii. 469.

Allium ascalonicum, &c., scent, ii. 488.

Allium Cepa, ii. 731.

— — absorbent cells of cotyledon, i. 600.

— — fistular leaves, i. 428.

— — germinating seed, i. 599.

Allium Chamzmoly, flowers and autogamy,

ii. 386.

— — nectaries, ii. 175.

— — plant, ii. 386.

—— scent, ii. 199, 203.

—— stamen movements, ii. 303,

Allium fistulosum, fistular leaves, i, 428.

Allium obliquum, leaf twist, i. 429.

Allium odorum, origin of accessory embryos,
ii, 469.

Allium pater-familias, numerous bulbs, ii.
831.

Allium porrum, ii. 731.

Allium rotundum, leaf twist, i. 429.

— — staminal stipules, ii. 89,

Allium sativum, cotyledon and germination,
i. 606.

Allium Schcenoprasum, ii. 488.

— — fistular leaves, i. 428.

Allium scorodoprasum, ii. 731.

Allium senescens, leaf twist, i. 429.

Allium Sibiricum, scent of flowers and
foliage-leaves, ii. 199.

Allium Spherocephalum, stamen, ii. 87.

~—— staminal stipules, ii. 89.

Allium suaveolens, scent of flowers and
foliage-leaves, ii. 199.

Allium ursinum, bud, emerging from soil,

i. 640.

— — habitat, i. 654.

Allium Victorialis, geitonogamy, ii. 327.

— — stigma, ii. 283. 4

Allium vineale, mechanical tissue arrange-
ment, i. 730.

Allosorus, protection of sporangia, ii. 13.

— two kinds of fronds, ii. 12, 476.

Allosorus crispus, i. 451.

Allurement, means of, in pitchers, i. 124,

Alluring substances, i. 460.

Almond oil, decomposition, i. 462.

Almonds, conglutin, milk of, i. 458,

Alnus and gall-mites, ii. 529.

— arr t of foliage-lea

— flowering, ii. 150.

— moneecious, ii. 297.

— phyllotaxis, i. 399.

— pollen-grain, ii. 102.

— pollen storing and dispersion, ii. 94, 148.

— pollination, ii. 133, 135.

— protection of pollen, ii. 119.

— protogynous, ii. 313.

— roots, i. 752.

— texture of mite-galls, ii. 532.

8, 1. 92.

927

Aloé, aqueous tissue, i. 328,

— caudex, i. 714.

Aloé denticulata, pollen-grains,ii. 97,
Aloes, ii. 731.

— Cape, mucilaginous juices, i. 329.

— germination, i. 604.

Alonsoa, scarlet flowers, ii. 196.
Alopecurus, pollination, ii. 142.

Alpine and Arctic floras, ii. 905.

— experimental garden, Kerner’s, i. 393.

— floras, autogamy in, ii. 400.

— flowers, multiplicity of colours, ii. 198.

— flowers in the Tyrol, ii. Pl. XII.

— plants, high, characteristics of, i. 315.

— Rose. See Rhododendron hirsutum.

— Rose-apples, ii. 520.

—Vine. See Atragene alpina.

— Willows, Tyrol, i. 524.

Alpinia, ii. 289, 736.

— hermaphrodite, ii. 296.

Alps, Central Europe, autumnal tints, i. 489.
— Central, lime incrusting Saxifrages, i. 71.
—— meadows, herbage, i. 451.

— early leaf-fall in, i. 357.

— protected vegetation, i. 450.

— red snow in, i. 38.

— Tyrolese, established hybrids in, ii. 588.
— — observations relating to ammonia, i. 65.
— — soil, temperature, and elevation, i. 525.
— winter cold, i. 547.

Alsike Clover. See Trifolium hybridum
Alsine Gerardi, autogamy, ii. 355.

Alsine mucronata, nectaries, ii. 176.

Alsine rubra, weather and autogamy, ii. 391.
Alsine verna, cross-fertilization, ii. 307.

— — nectaries, ii, 176.

Alsinex, autogamy, ii. 337.

Alsophila, ii. 4'73.

— caudex, ii. 705.

— sorus and indusium, ii. 708.

Alsophila excelsa, dimensions of caudex, i.

Alternation of generations, ii. 7.

— — advantage of, ii. 484.

— — among zoophytes, ii. 470.

—— and origin of species, ii. 594.

— — in Alga, ii. 481.

— — in Mosses, ii. 477, 479.

— —in Phanerogams, ii. 478.

— — in Thallophyta, ii. 480.

Altbza officinalis, stomatal protective hairs,
i, 292.

Althwa pallida, effect of mutilation, ii. 517.

— — sheltering of pollen, ii. 108.

Althea rosea, sheltering of pollen, ii. 108.

Alumina in cell-wall, i. 72.

— in dust, i. 81.

— rarely absorbed, i. 68.

Alyssum, nectaries, ii. 175.

— peripheral flowers, ii. 186.

Alyssum calycinum, autogamy, ii. 339,

—— colour contrast in inflorescence, ii. 192,

Alyssum cuneatum, umbellate raceme, ii.
184.

Alyssum montanum, i. 325.

—— scent, ii, 202.

Alyssum Wierzbickii, hairs, i. 321.

Alyssum Wulfenianum, peripheral flowers,
ii. 186.

Amanita muscaria. See Agaricus muscarius,

Amanita phalloides, basidia and spores, ii.
21, 685.

Amaranth, green. See Amarantus Blitum.

Amarantl bracts, ii. 750.

Alnus glutinosa and gall of Cecidomyia alni,
ii, 534,

—— &c., bracts and Exoascus Alni-incane,
ii, 524.

— — chalazogamic fertilization, ii. 413.

— — inflorescences, ii. 135.

— — root-galls, ii. 521.

Alnus incana and Exoascus epiphyllus, ii. 527.
— — two-coloured leaves, habitat, i. 293.
——with galls of Exoascus Alni-incana, ii.

523. Pm
Alnus orientalis, mite-galls, ii. 529,
Alnus viridis, and snow, i. 550.
— — mite-galls, ii. 529.

— leaf-rosettes, i. 412.

— perianth, ii. 749.

Amarantus Blitum, leaf-mosaic, i. 411.
Amaryllidacex, autogamy in, ii. 372.
— characteristics, ii. 734.

— epiphyllous buds, ii. 43.
Amaryllis, ii. 734.

— buds on carpels, ii. 44.

— cross-fertilization, ii. 301.

— incompletely protogynous, ii. 311.
— ovular tubers or buds, ii. 469.

— pollen-grains, ii. 99, 100.

— scentless, ii. 209.

928

Amaryllis aulica, size of flowers, ii. 185.

Amaryllis Belladonna, flowers and change of
temperature, ii. 503.

Amaryllis equestris, &c., size of flowers, ii. 185.

Ambras, castle of, in Tyrol, Lichens on pil-
lar, i. 247.

Amelanchier vulgaris, decid
woolly hairs, i. 354,

Amentaces, ii. 719.

— bracts and fruit, ii. 434.

— chalazogamic fertilization, ii. 412, 616.

— more than one embryo-sac in, ii. 478.

— numerous hybrids of, ii. 583.

— table of modes of fertilization, ii. 413.

Amentales, ii. 762. :

Ambherstia nobilis, scarlet flower, ii. 196.

Amide, formation, i. 458.

Amides, especial function, i. 464.

Aminoid scent, ii. 199,

— — insects attracted by, ii. 207.

Ammonia, i. 263.

— absorption by glandular hairs, i. 65.

— absorption from atmosphere, by plants
with water-receptacles, i. 241.

— absorption with atmospheric water, i. 156.

— sources of and relation to plants, i. 65.

Amcebe, i. 137.

— feeding of, i. 56.

— of Myxomycetes, specific individuality, ii.
490.

us protective

Amorpha fruticosa, &c., reserve-buds, ii. 32.

— — leaf, day and night positions, i. 533.

— — leaf-movements, i. 338.

Amorphophallus titanum, description, ii. 745.

Ampelidex, anthocyanin, i. 484.

— extra-axillary buds, ii. 28.

— protection of pollen, ii. 124,

Ampelopsis, Pl. V. i. 488.

— tendrils, i. 699.

Ampelopsis hederacea, crystals, i. 457.

Ampelopsis inserta. See Vitis inseria.

Ampelopsis quinquefolia, allurement of bees,
ii. 206.

— separation-layers, i. 360.

Amphibious plants. See also Plants.

— — characteristics, ii, 501.

Amphibrya, of Endlicher, ii, 604.

Amphicarpium, meaning, ii. 47.

Amphigastria, of Frullania, ii. 698.

— of Jungermanniacee, ii. 699.

Amphigonium, meaning, ii. 47.

— of Chara, ii. 63.

—of Muscinee, and Vascular Cryptogams,
ii. 62, 64, 67, 659.

Amphiloma, various species, situation on
column at castle of Ambras, i. 247.

Amphoridium Mougeotii, parthenogenesis,
ii, 464,

Amygdalin, decomposition, i. 462,

Amygdalus, nectary, ii. 174.

— petals after pollination, ii. 286,

— phyllotaxis, i. 400.

— pollen-grains, ii. 99.

— receptacle and carpel, ii. 76.

Amygdalus communis, ii. 202.

— — cotyledons, i. 608.

— — flower, ii. 77.

— — flower-opening constant, i. 559.

Amygdalus nana, reserve-buds, ii. 33.

Amygdalus Persica, evergreen in African
oases, i. 358.

—— impossibility of grafting on Salix, i.

15.

Anabrena Flos-aquee, habitat, ii. 621.

Auacamptis and Orchis, hybridization, ii.
583.

Anacamptis pyramidalis, flower-colour and
lovality, ii. 194. .

Anacardium occidentale, fruit, ii. 436.

Anacyclus officinarum, anthocyanin in ligu-
late florets, ii. 220,

Anadyomene, thallus, ii. 646.

Anagallis, colour of flowers, ii. 183, 567.

— corolla and autogamy, ii, 368.

— edible staminal hairs, ii. 170.

— germination constant, i. 558,

— prostrate, i, 664.

INDEX,

Anagallis, seed and embryo, ii. 422.

Anagallis arvensis, buds on hypocotyl, ii, 28.

— — latitude and opening, ii. 217.

— — origin of flower-stalk, i. 737.

Anagallis Philippi, withering of corolla and
pollination, ii. 286.

Anagallis phoenicea, protection of pollen, ii.
120.

—— seed and embryo, ii. 422.

Anamirta Cocculus, ieaf-stalk bundles, i.
649.

Ananassa sativa, collective fruit, ii. 436, 734.

— — inflorescence, i. 738.

— — seed and embryo, ii. 425.

Anaphyte, or shoot-member, ii. 470.

Anaphytes, application of term, ii. 6.

— sorts of, ii. 470.

Anastatica Hierochuntica, opening and clos-
ing due to hygroscopic changes, i. 344.

— — seed-dispersal, ii. 845.

Anatomy, influence of habitat on, ii. 511.

— of plants, Nehemiah Grew’s, i. 22.

Anatropous ovule, i. 644.

Anatto, See Bixa Orellana.

Anchusa, corolla and autogamy, ii. 367.

— cotyledon bristles, i. 623.

— pollen grains, ii. 99.

Anchusa officinalis, leaf and climate, i. 325.

Ancylistacee, ii. 668, 671.

Andrea, ii. 480, 701.

— collection of dust, i. 266,

— spore-dispersal, ii. 814.

Andrezea rupestris, ii. '700.

— — sporogonium, ii. 15.

Andrezacex, characteristics, ii. 701.

Andrena, pollination of Cypripedium Calceo-
lus, ii. 246, 249.

— sheltering in flowers, ii. 163.

Andricus, oviposition in various places, ii.
540.

Andricus inflator, bud-galls on oak, ii, 543.

Andreecium, meaning of term, ii. 86.

— of Colocasia antiquorum, ii. 742.

Androgonidia, of Volvox, ii. 634.

Andromeda, pollen tetrads, ii. 97.

Andromeda hypnoides, Arctic, absence of
hairs, i. 316.

Andromeda polifolia and Exobasidium Vac-
cinii, fi, 527.

— — wax on leaves, i. 302.

Andromeda tetragona, cuticular rods on
leaves, i. 302.

— — rolled leaf, transverse section, i. 301,

Andropogon, hermaphrodite and staminate
flowers, ii, 297.

— pith, ii. 746.

— pollination, ii. 142.

Androsace, heterostyly, ii. 302.

— hybrids, ii, 585.

— nectary, ii. 175.

— protection of pollen from wet, ii. 111.

Androsace elongata, &c., autogamy, ii. 341.

Androsace maxima, anthocyanin, i, 521.

Androsace obtusifolia, white flowers, ii, 198.

Androsace sarmentosa, Himalayas, runners,
i. 664.

Androsemum, twisting of internodes, i. 417.

Androspores, of GEdogonium, ii. 651,

Andryala, hairiness, i. 317

Aneimia, sporangia, ii. 709.

Anemone, zestivation, ii. 210,

— alluring petals, ii. 170. i

— hybrid flower, colour, ii. 567.

— hybrids, ii. 584.

— insect reception, ii, 229.

— insects and pollen, ii. 244.

— opening of flower, ii. 220.

— protection of pollen, several means, ii. 127.

— protogynous, ii. 311.

Anemone alpina, autogamy, ii. 382.

— — &c., anthocyanin in sepals, ii. 220,

— — flower-colour and locality, ii. 194,

— — habitat, i, 113.

— — nectarless, ii, 167.

Anemone baldensis, autogamy, fi. 381.

— — flowers, sexual conditions, ii. 303.

— — nectarless, ii. 167.

Anemone Hepatica, altitude and opening,
ii, 218.

——autogamy, ii. 345.

—— colour-contrast of flower, ii. 189.

—— nectarless, ii. 167.

—— protection of pollen, ii. 114, 127.
Anemone intermedia, hybrid, colour of
flowers, ii. 567. :
Anemone nemorosa and A. ranunculoides,
colour of flowers and hybrid, ii. 567.

— — attacked by Sclerotinia, ii. 682.

——carpels, ii. 229.

—— colour of sepals, ii. 183, 220.

—— complete plant, ii. 229. =

— — effect of Aicidium of Puccinia fusca, ii.

524.

— — flower, polyandria, ii. 292.

— — hermaphrodite, ii. 296.

— — protection of pollen, ii. 120.

Anemone Pulsatilla, autogamy, ii. 389.

Anemone sylvestris, dissemination, i. 615.

— — nectarless, ii. 167.

— — plumed fruits, ii. 855.

Anemone Transylvanica, autogamy, ii. 345.

Anemone trifolia, anthocyanin in sepals, ii.
220.

Anemone vernalis, autogamy, ii. 389.

— — effect of mutilation, ii. 517.

Anemophilous plants, ii. 129, 719.

— — and hybridization, ii. 583.

—— characteristics and number, ii. 133.

— — pollination, ii. 139. :

Anethum graveolens, foliage and light, i.
412.

Aneura, apical-cell, i. 578. 4

Angelica, water-receptacles, i. 240.

Angelica officinalis, scent, ii. 202.

Angelica sylvestris, fruit, ii. 428.

— — mericarp, ii. 430.

Angiopteris, sporangia, ii. 709.

Angiosperme, distinctive characters, ii. 719,
728.

— embryo development, ii. 420.

— fertilization, ii. 417.

— germination, &c., of pollen-grains, ii. 408.

— mesozoic, ii, 613.

— protection of ovules, ii. 72.

— two classes, ii. 728.

Angiospermous trees, healing of wounds, ii.
29.

Angreecum eburneum, epiphytic, ii. 737.

Angreecum funale, chlorophyll in roots only, .
i. 375,

Angrecum globulosum, chlorophyll in roots
only, i. 375.

Angrecum Sallei, chlorophyll in roots only,
i. 375.

Angreecum sesquipedale, length of spur, ii.
180.

Animal captors, with movement, i, 148.

Animals, agents in offshoot-dispersal, ii. 827.

— and colour sense, ii. 195.

— and plants, as a symbiotic community, i.
254.

— browsing, protection against, ii. 445.

— dispersal of seeds by, ii. 862.

— elevation and coloration, ii. 511.

— number captured by Utricularia, i. 122.

Anisogametes, of Bryopsis, ii. 645.

Annual plants, ii. 452,

— — and lack of moisture, ii. 500.

— — foliage stems, i. 656.

—— steppe and desert, heat-resisting seeds,

i. 556.

Annual ring, nature of, i. 476, 719.

Annulus, of Agaricines, ii. 689.

— of fern-sporangium, ii. 705.

— of moss-capsule, ii. 702.

— of Schizeeaces, ii. 709.

Anoda hastata, autogamy, ii. 355,

— — protection of pollen, ii. 120.

Anona, pollen tetrads, ii. 97.

Anonaces, aggregate fruits in, ii. 436, 487.

Antennaria alpina. See Gnaphalium alpinum,

Anthemis, foliage and light, i, 412.

— geitonogamy, ii. 322,

Auther, application of term, i. 642.

Anther, archesporium, ii. 95.
— contractile cells, ii. 93.
— extrorse position and protection of pollen
of, ii, 126.
— morphological value, ii. 88,
— variations in form, ii, 90.
Anthera, i, 642.
Anthericum, cross-fertilization, ii. 301,
— nectaries, ii. 175.
Antheridium, definition, ii. 47,
— of Achlya lignicola, ii, 671.
— of Bryum ceespitosum, ii. 700.
— of Chara fragilis, ii, 63, 660.
— of Coleocheete, ii. 653.
— of Dudresnaya, ii. 53.
— of Equisetaces, ii. 68.
— of Erysiphew, ii. 59.
— of Ferns, ii. 67, 275, 472, '708.
— of Florides, ii. 61.
— of Fucus vesiculosus, ii. 664.
— of Hepatics, ii. 696.
— of Hydropterides, ii. 710.
— of Marsilia, ii. 69.
— of Mosses, ii. 15, 65, 701.
— of Edogonium, ii. 651.
— of Peronospores, ii. 56, 669.
— of Salvinia, ii. 69.
— of Saprolegniaces, ii. 484, 670.
— of Selaginella, ii. 69, 715.
— of Vaucheria, ii. 643.
Anther-lids and insects, ii. 129.
Antherocerotacez, description, ii. 698,
Anthers and nocturnal radiation, i. 529.
—and stigmas, change of position, ii, 305.
— exsertion in grasses, ii. 140.
— in cleistogamous flowers, ii. 392.
— opening and closing, ii. 124.
Anthobium, pollen devourer, ii. 167.
—sheltering in flowers, ii. 163.
Anthoceros and Nostoc, ii. 622.
— chlorophyll bodies, i. 373.
Anthocyanin, and light, ii. 510.
— description, location, &c., i. 483.
— fluorescence and function, i. 379, 519, 522;
ii, 220,
— pigment, i. 460.
— use to floating leaves, i. 288.
— violet and red, i. 486.
Antholysis, caused by gall-mites, ii. 548.
— meaning of term, ii. 80, 82.
— of Delphinium cashmirianum, ii. 78.
Anthomyia and Dracunculus Creticus, ii.
165. i
Anthopeziza Winteri, ii. 683.
Anthophyta, of Braun, ii. 605.
Anthoxanthin, pigment, i. 460.
Anthoxanthum, pollination, ii. 142,
— scent, ii. 201.
Anthoxanthum odoratum, dichogamy, ii.
312.
Anthrax, cause of, i. 163.
Anthrenus, honey-sucker, ii. 179.
Anthriscus, geitonogamy, ii. 325.
— flowers, sexual conditions, ii. 296,
— how protected, i. 451.
Anthriscus sylvestris, arrangement of um-
bels, i, 740.
-Anthurium, scarlet spathe, honeyless, ii. 196.
Anthurium Scherzerianum, coloured bract,
ii, 184.
Anthyllis, pollen expulsion, ii. 260.
— variability of floral colour, ii. 569.
Anthyllis Vulneraria and Polyommatus
Hylas, ii. 156.
—— dispersed by wind, ii. 848.
—— flower, ii. '7'79.
-- — pollen-grains, ii. 99.
— — tubercles on root-fibres, ii. 521.
Antiaris toxicaria, ii, 758.
Antipodal cells and polyembryony, ii, 469.
—— of embryo-sac, ii. 416.
Antirrhinum, sstivation, ii. 211.
— and insects, ii. 210, 247.
— capsule, ii. 431.
— flower, didynamia, ii. 292.
— honey concealment, ii. 180.
.Antirrhinum, insect platform, ia. 228,

VoL, II,

INDEX,

ee cirrhosum, leaf-stalk tendrils,

i. 692.

Antirrhinum majus, attraction of foreign
pollen-tubes by ovules, ii. 414,

— — direction of flowers, ii, 225.

— — seed and embryo, ii. 422.

Antiseptics, effect on bacteria, i. 263.

Ants, allured by Sarracenia, i. 128,

— disperse seeds, ii. 866.

— in pitchers of Cephalotus, i. 131.

— protection of Serratula, ii. 242.

— symbiosis with plants, ii. 233, 243,

Apera, pollination, ii. 142,

ee spica-venti, dimensions of grain, ii.

Apetala, of Endlicher, ii. 604.

Apetale, of de Jussieu, ii. 602.

Aphanizomenon Flos-aque, habitat, ii. 621.

uaa phycophilus, parasitic on algz,
IL. i.

Aphid mimicry, by Eremurus, ii, 171.

Aphides and stamens, ii. 87.

Aphilothrix gemma, bud-galls on oak, ii.
541, 543.

Aphis, parthenogenesis, ii. 464.

Baca pi Monspeliensis, autogamy, ii.

1,

— — duration of flowering, ii. 213.
Apical-cell, division and nature, i. 578.
Aplanogametes, of Conjugate, ii. 654,
Aplanospore, formation in Gonatonema, ii.
658.
— of Chlorophycez, ii. 628,
— of Phyllosiphon, ii. 643.
Apocynaces, ii. 771.
— estivation in, ii. 210.
— cohering pollen-grains, ii. 97.
— decussate phyllotaxis, i. 398.
— soft bast, i. 477.
Apodanthacez, ii. 755.
Apodanthes, limited distribution, i. 204,
— size of flowers, i. 202.
Apodanthes Flacourtiana, mimicry of
Daphne Mezereum, i. 201.
Aponogetacex, characteristics, ii. 738.
Aponogeton distachyon, autogamy, ii. 335,
— — flower-spikes, ii. 738.
A ton le,
heat, i. 554,
— — habit, i. 666.
A sis, of moss le, ii. 702.
Aposeris foetida, milky juice, i. 451,
Apostasiacez, stamens, ii. 736.
Apothecia, of Peziza, ii. 682.
— true nature, ii. 20.
Apparatus, capturing, in Aldrovandia and
Dionza, i. 150.
——in Lathrea, Bartsia, Pinguicula, i. 137.
— for pollen transference, ii. 260.
Apple, section, ii. 74.
Apple-tree. See Pyrus malus,
— — host of Mistletoe, i. 205.
Apricot. See Prunus Armeniaca.
Aptogonum Desmidium, ii. 492, 655.
Aquatic plants, source of oxygen, i. 493.
Aquatic root, i. 752.
— — origin, i. 766.
Aqueous tissue, conduction of carbonic acid,
i, 330.
— — in offshoots, ii. 833.
— — of leaves, i. 312.
— — of succulent plants, i. 328.
Aqueous vapour, maintenance of free pas-
, sage for, in plants, i. 290.
Aquilegia, nectaries, ii. 178.
— protection of pollen, ii. 118.
— sticky species, ii. 235.
Arabia, gum-arabie, i. 458.
Arabian desert regions, hairiness of plants,
i. 318.
Arabis brassiceeformis, anthocyanin, i. 520.
Arabis coerulea, autogamy, ii. 335,
— —colour-contrast in inflorescence, ii. 192,
— — weather and autogamy, ii. 391.
Arabis procurrens, elevation and coloration,
ii. 511.
Arabis pumila, epiphyllous buds, ii. 43.

Mad and

929

Arabis Turrita, protection of pollen, ii. 121.

Arachnoidea, gall formation, ii. 527.

Aralia, colour and flies, ii. 197.

Aralia J: ica, flower, dria, ii. 289.

Aralia nudicaulis, flowers, sexual conditions,
ii. 296.

Araliacer, drinkable sap, i. 272.

— protection of pollen, ii. 124.

Araucaria, axillary buds, ii. 29.

Araucaria imbricata, cones, ii. 720.

Araucariacex, distinctive characters, ii. 720.

Araujia albens, moth-catching, ii. 259.

Arbor, i, 715.

Arbor vite, leaves and transpiration, i. 326.

— — twig, i. 410.

Arbuscula, i. 715.

Arbutacez, ii. 768,

Arbutus, mycorhiza in, i. 251.

— pollen sprinkling, ii, 274.

— pollen tetrads, ii. 97.

Arbutus Unedo, ii. 422, 769.

Arcella, gas bubble secretion, ii. 622.

Arcenthobium Oxycedri. See Viscum Oxy-
cedri.

Arched leaf, structure, i. 430.

Archegoniatz, ii. 617.

— characteristics, ii. 696.

Archegonium, of Bryum czspitosum, ii. 700.

— of Chara fragilis, ii. 660.

—of Characez, Muscines, and Vascular
Cryptogams, ii, 62.

— of Ferns, ii. 472, 475, 708.

— of Gymnosperms, ii. 419,

— of Hepatice, ii. 696.

— of Mosses, ii. 15, 64.

Archesporium, of anther, ii. 95.

Archichlamydez, of Eichler and Engler, ii.
616.

Arctic flora, autogamy in, ii. 400.

— regions, plants of, not hairy, explanation,
i. 316.

Arctostaphylos, and animals, i. 432.

— autogamy, ii. 379.

— honey protection, ii. 239.

— nectaries, ii. 177.

— pollen sprinkling, ii. 247

— pollen tetrads, ii. 97.

— sticky stigmas, ii. 282.

Arctostaphylos alpina, stamen, ii. 91.

Arctostaphylos Uva-Ursi, i. 490.

— — and Exobasidium Vaccinii, ii. 527.

— — flower, ii. 240.

— — procumbent habit, i. 662.

— — protogynous, ii. 310.

Arcyria, sporangia, ii. 491, 618.

Arcyria punicea, capillitium, ii. 491, 618.

Arex, characteristics, ii. 745.

Areca disticha, ii. 741.

Aremonia agrimonioides,
flowers, ii. 392.

Arenaria, pollen-grains, ii. 99.

Arenaria rubra, latitude and opening, ii.
212, 217.

Aretia, heterostyly, ii. 302.

—-nectary, ii. 175.

— protection of pollen from wet, ii. 110.

Argemone, corolla and autogamy, ii. 369.

— flower shape, &c., ii. 167, 168.

— insect platform, ii. 229.

Argemone Mexicana, flower and autogamy,
ii. 369.

—— ovary, ii. 776.

Aril, nature of, ii. 424.

— of Taxus, ii. 442.

Ariopsis, monoecious, ii. 297.

— tubers, ii. 745.

Ariopsis peltata, ii. '742.

—— sheltering of pollen, ii. 108, 110.

— — vertical range, ii. 745.

Arisarum vulgare and Phyllosiphon Arisari,
ii. 643.

Arisema, moneecious, ii. 297.

Arisema ringens, Japan, sheltering of pollen,
ii. 108.

Aristida, fruit, i, 620.

Aristolochia, allied to Nepenthes, i. 134.

— capsule, ii. 431.

cleistogamous

109

930

Aristolochia, colour and odour, ii. 197.
— imprisonment of insects, ii. 165. "
— insect platforms, ii. 225,
— nature of scents, ii, 199.
— perianth, ii. 165.
— stem, i. 364.
Aristolochia Clematitis, allurement of in-
sects, ii. 206, 222.
—— flower, gynandria, ii. 292.
— — food of Thais Hypermnestra, ii. 488.
— — insect platform, ii. 226.
— — odour, i. 431.
— — pollination, ii. 244.
— — venation, i. 633.
Aristolochia Gigas, scent, ii. 200.
——var. Sturtevantii, size and colour of
flowers, ii. 185.
Aristolochia ringens, flowers, ii. 166.
— — insect platform, ii. 225.
Aristolochia Sipho, leaf-blades, i. 649.
— — sinistrorse twining, i. 685.
Aristolochiacez, ii. 599, 755.
— American, size of flowers, ii. 185,
— protogynous, ii. 312.
— South American, i. 202.
Aristotle, biology of plants, i. 16.
Armeria, pollen-grain, ii. 100.
— stigma, ii. 281.
Armeria alpina, autogamy, ii. 358.
— — seed-dispersal, ii. 854.
Armeria vulgaris, autogamy, ii. 358.
Arnebia cornuta, fruit protection, ii. 442.
Arnica, flowers, sexual conditions, ii. 296.
— habitat, i, 112.
— pollination, i. 740.
Arnica montana and Campanula, colour con-
trast, ii. 193.
— — florets and autogamy, ii. 363.
— — flower-opening constant, i. 559.
— — peripheral flowers, ii. 187.
Arnoseris pusilla, persistent cotyledons, i. 622.
Aroidee, ii. 742.
— adherent roots, i. 108.
— adventitious roots, i. 751.
— aérial roots, i. 365, 753; ii. 745.
— arrangement of roots, i. 766.
— certain, resemblance to Leucobryum and
Sphagnum in water-absorption, i. 220.
— coloured bracts in, ii. 183,
— description, ii. 742.
— development of climbing roots, i. 705.
— epiphyllous buds, ii. 43.
— epiphytic, aérial roots, porous covering
and root-hairs, i. 223.
— extrusion of water from leaves, i. 271.
— geitonogamy in, ii. 325.
— geographical distribution, ii. 745.
— imprisonment of insects, &c., ii, 164.
— inflorescence, i. 501.
— insects and pollen, ii, 222, 244.
— leaf perforation, i. 413.
— leaves of, structure in relation to trans-
piration, i. 288.
— moncecious, protogynous, ii. 313.
— nature of scents, ii. 199.
— on ground of woods, i. 109.
— on trees, i. 106.
— origin of roots, i. 771.
— pericarp mucilage, i. 615.
— pollen-grain, ii. 100.
— sheltering of pollen, ii. 108.
— temperature within spathe, i. 501.
Arolla pine. See Pinus Cembra.
Aronia rotundifolia, Gymnosporangium gall,
ii. 521.
Aronicum glaciale, dichogamy, ii. 312.
Arrangements for reception of insects, ii.
226, 227.
— for retention of pollen, ii. 279.
Arrhenatherum, flowers, sexual conditions,
ii, 297.
Arrow-head. See Sagittaria.
Arrowroot, source of, ii. 736.
Artedia squamata, seed-dispersal, ii. 853.
Artemisia, as host of Orobanche, i. 185.
— hairiness, i. 317, 319.
Artemisia Absynthium, ii, 87.

INDEX,

Artemisia Absynthium, &c., hairs, i. 322.

Artemisia campestris, and gall of Cecido-
myia Artemisia, ii. 547.

Artemisia Mutellina, &c., geitonogamy, ii.
322.

— — habitat and hairiness, i. 316.

Arthrospore, of Bacteria, ii. 623.

Artichoke. See Cynara scolymus.

Artocarpaces, ii. 758.

— collective fruits in, ii. 436.

— laticiferous tubes, i. 470.

— pollen-grains, ii. 97.

Artocarpus incisa, flowering and fruiting
branch, ii. 438.

— — from chalk, ii. 613.

Artocarpus integrifolia, collective fruit, ii.
436.

Arum, moneecious, ii. 297.

— pollination, ii. 164.

Arum conocephaloides and Ceratopogon, ii.
165.

— — inflorescence, ii. 164.
Arum cordifolium, temperature within
spathe, i. 501.

Arum Italicum, fly visitors, ii. 165.

—— geographical distribution, habitat, i.
501.

— — temperature within spathe, i. 501; ii. 164.

Arum maculatum and Psychoda phalle-
noides, ii. 165.

— — habitat, i. 654.

—— leaf of, i. 286.

Arundinaria gl pre of sto-
mata from moisture, i. 294.
Arundo, arr tt for rail ter exclu-

sion between haulm and leaf, i. 98.

Arundo Donax, dimensions, i. 714.

— — reserve-buds, ii. 32.

A ida. See Scorod Asafatida,

Asarabacca. See Asarum Europeum.

Asaracez, ii. 755.

Asarum, eestivation, ii. 210.

— leaf, emerging from soil, i. 640.

— pollen-deposition, ii. 279.

— pollen-grain, ii. 100.

— variety of scent, ii. 488.

Asarum Canadense, creeping stem, i. 662.

Asarum Europeum, creeping stem, i. 662.

—— stages in blossoming, ii. 279.

— — venation, i. 633.

— — winter protection, i. 550.

Ascherson, Flora der Provinz Brandenburg,
ii. 605.

Asci, ii. 19.

— of Claviceps, ii. 680.

— of Cordyceps, ii. 679.

— of Erysiphe, ii. 60.

— of Morchella, ii. 683.

— of Moulds, ii. 677.

— of Tuber, ii. 678, 681.

Ascidia, i. 127.

— alluring, &c., contrivances, i. 128,

—as pitfalls, &c., i. 123.

Asclepiadacem, i. 470; ii. 77.

— cleistogamy in, ii. 393.

— corpusculum, ii. 257.

— insect-visitors, ii. 258.

— pollinia, &c., ii. 97, 257, 259.

— protective sticky latex, ii. 234,

—soft bast, i. 477.

— viscin of pollen-grains, ii. 101.

Asclepias, scent, ii. 202.

Asclepias Cornuti, clips on insect foot, ii. 259.

— — floral mechanism, ii. 258.

—— radical buds, ii. 28.

Ascoidew, ii. 674.

Ascomycetes, ii. 606.

— asci and spore formation, ii. 18.

— distinctive characters, ii. 676,

— various, ii. 679, 681.

Ascophyllum, ii. 664.

Ascosporez, ii. 606.

Ascospores, of Ascomycetes, ii. 19, 676, 693.

Ascus, of Podosphzera, ii. 60.

— of Xylaria, ii. 679.

Ascus-fruit, basis of classification in Asco-
tmaycetes, ii. 676,

Ascus-fruit of Eurotium, ii. 679.

—— of Moulds, ii. 677.

Asexual generation of ferns, commencement
of, ii. 472.

Asexual reproduction, in Mucorini

Saprolegniacez, ii. 480, 481.

— — in Saprolegniacez, ii. 484.

Ash, essential constituents of, ii. 66.

— of chlorophyll, i. 371.

—of Stratiotes aloides, Nymphza alba.
Chara foetida, Phragmites communis,
Biscutella levigata, Doryenium decum-
bens, i. 69.

— of Taxus baccata, i. 70.

Ash. See Fraxinus excelsior.

— mountain. See Sorbus Aucuparia,

Asparagin, i. 464.

— an amide, i. 458.

—and respiration, i. 495.

Asparagine, switch-plants in, i. 330.

Asparagus, ii. 732.

— phylloclades, i. 652.

Asparagus acutifolius, &c., weaving habit,
i. 674.

Asparagus horridus, &c., spines, i. 434.

Asparagus officinalis, distribution of sexes,

ii. 299.

— — imperfect flowers, ii. 294.

Aspen. See Populus tremula.

Aspergillex, fertilization and fruit-forma-
tion, ii. 60.

Aspergillus, fermentative action, i. 508.

— parasitism, ii. 678.

— sporangia, &c., ii. 18, 21.

Aspergillus fumigatus, habitat, ii. 678.

Aspergillus niger, conidial hyphe, ii. 677.

Asperula, stipules, i. 637. |

Asperula aparine, weaving habit, i. 674.

Asperula arvensis, artificially induced
drooping, ii. 123.

Asperula capitata, evening smell, ii. 209.

Asperula galioides, cuckoo-galls, ii. 545.

Asperula glomerata, opening of flower, ii.
212.

Asperula longiflora, &c., scent, ii. 200.

Asperula odorata, ii. 537.

— — effect of clearing wood, i. 391.

— — leaf and illumination, i. 286.

hanical tissue

— — stamens, ii. 86.

— — winter protection, i. 550.

Asperula taurina, behaviour of styles, i.
740.

— — geitonogamy, ii. 325,

— — sexual conditions, ii. 296.

Asperula tinctoria, cuckoo-galls, ii. 545.

Asphodel, Scottish. See Tofieldia borealis.

Asphodeloide, char istics, ii. 730.

Asphodelus, protogynous, ii. 311.

Asphodelus albus, roots, i. 760.

— — twisted leaves, i. 429.

Asphodelus ramosus, at Peestum, ii. 730.

Aspicilia calcarea, heat resistance, i. 554.

Aspicilia flavida, habitat, i. 117.

Aspidies, sorus and indusium, &c., ii. 706.

Aspidium, hybrids in, ii. 582.

Aspidium falcatum, apogamy, ii. 458.

Aspidium Filix-mas, winter buds, emergence
from soil, i. 639,

Aspidium Thelypteris, necessary soil, ii. 612

Aspleniez, sorus and indusium, ii. 706.

Asplenium, buds on fronds, ii. 39, 41.

— hybrids in, ii. 582.

— prothallus, ii, 11.

Asplenium Germanicum, hybrid of A. Ruta-
muraria X A, septentrionale, ii. 586.

— Ruta-muraria, sporophyte and prothal-
lium, ii. 472.

Asses, wild, and Melocactus, i. 447.

Assimilation and respiration, i, 492-495.

— theory of, i. 456.

Aster, and ancient crossing, ii, 555.

— autogamy, ii. 359.

— Blue. See Aster Amellus.

— colour-contrast in capitulum, ii. 191.

— flowers, sexual conditions, ii. 296.

— geitonogamy, ii. 321.

and

t, 1. 730.

Aster, pollination, &., i, 740; ii. 284, 286.

Aster alpinus, dichogamy, ii. 312.

— — florets and autogamy, ii. 360.

Aster Amellus, flower-opening constant, i.
559,

Aster urgophyllus, hairs, i. 321.

Aster Tripolium and flooding, ii, 500.

Asterales, ii. 765.

Asteriscus pygmeous, seed-dispersal, ii. 845,

Asteroides, autogamy in, ii. 359.

— geitonogamy, ii, 321,

Astragalus, alternating axes, i, 658.

— explosive flowers, ii. 267.

— hairs, i. 321.

— spines, i. 447,

Astragalus exscapus, i. Pl. VI.

Astragalus Onobrychis, i. Pl. VI.

Astragalus Tragacantha, spines, i. 447, 449.

Astragalus vesicarius, flower-colour and
habitat, ii. 194.

Astragalus virgatus, i. P). VI.

Astrantia, coloured bracts, ii. 183,

— geitonogamy, ii. 323.

— flowers, sorts of, ii, 296.

— protogynous, ii. 311.

Astrantia alpina, &c., protection of pollen,
ii, 120.

Astrantia major, artificially induced droop-
ing, ii. 123.

Asvhatta. See Ficus religiosa.

Asyngamy, examples, ii. 885.

Athamanta, geitonogamy, ii. 324.

Athamanta cretensis, flowers, sorts of, ii. 296.

Athens, time of flowering at, i. 518.

Atherurus ternatus, epiphyllous buds, ii. 43.

Athyrium Filix-foemina, sorus and indusium,
ii. 706.

Atlas Cedar. See Cedrus atlantica.

Atmospheric conditions, adaptation of plants

to, ii. 502.
——and opening and closing of flowers, ii.
116.

—— in habitat of epiphytic Orchids, i. 222.

—moisture as source of nitrogenous com-
pounds, i. 241.

— water, gases in, i. 368,

Atoms, aggregation of, i. 57.

— combination, i. 452, 492.

— re-arrangement through sunlight, i. 378.

Atractylis cancellata, cotyledons in germina-
tion, i. 613.

Atragene, protogynous, ii. 311.

— ringed tendrils, i. 694.

Atragene alpina, alpine liane, i. 671.

—— autogamy, ii. 349.

— — colour of sepals, ii. 183.

— — flower, ii. 174.

— — leaf-stalk tendrils, i. 691.

— — nectaries, ii. 176.

—~ — nectary concealment, ii. 181,

~-—- protogynous, ii. 310.

-- — stem section, i. 138

Atraphaxis, gec hical di

— reserve-buds, ii. 33.

Atriplex, ii. 468.

Atriplex hastata, &c., scroll-gall, ii. 530.

Atropa, cross-fertilization, ii. 305.

— honey protection, ii. 239.

— pollen deposition, ii. 278.

-~ protection of pollen, ii. 118,

— sticky stigmas, ii. 282.

Atropa Belladonna, berry, ii. 427.

— — flower-opening constant, i. 559.

— — leaf-mosaic, i. 421.

— — poisonous properties, i. 431.

— — protection of pollen, ii. 128,

~ — rapid fertilization, ii. 285.

Atropine, i. 462.

Attachment disc, of Loranthus Europzus, i.

ii, 33.

— — of Mistletoe, i. 207, 209.

Aubrietia deltoidea, hairs, i. 322.

Aucuba Japonica, propagation by leaf-cut-
tings, ii. 41.

Aulacomnion androgynum, thallidia, ii. 23.

Aulacomnion turgidum, parthenogenesis, ii.

INDEX.

Aulax galls on Labiate, ii. 537, 543.
Aulax Hieracii bud-galls on Hieracium, ii.
543.

Auricles of Jungermanniaces, ii. 699.

Auricula, artificial breeding, ii, 555.

— longiflora, dichogamous blossoming, ii. 312.

— scent, ii. 201.

Auricularia sambucina, habitat, ii. 687.

Auriculariacez, basidia, ii. 680.

— characteristics, ii. 687.

Australia, hairiness of plants, i. 317,

— phyllodous acacias, i. 335.

— shadowless forests, i. 336.

Australian bush, chief components, i. 432.

Austria, flora of, i. 6.

Austrian Oak. See Quercus Austriaca.

Autogamy and size of flower, ii. 396.

— artificially produced, ii. 406.

— by agency of corolla, ii. 365, 369, 372, 375.

— by bending of pistil, ii. 350.

— by bending of stamens, ii. 337.

— by bending of stylar branches, ii. 360, 363.

— by calyx elongation, ii. 366.

— by coiling of stamens and style, ii. 343,
347.

—by combined movements, ii. 380, 383, 385,
386, 388.

— by contraction of style branches, ii. 359.

— by elongation of pistil, ii. 349.

— by inclination of curved st ii, 342.

— by inflection of flower-stalk, &c., ii. 380.

— by lengthening of stamens, ii. 334.

— by movements of flower-stalk, ii. 378.

—by pollen abstraction from corolla hairs,
ii. 363.

— by shortening of pistil, ii. 347.

— —— of stamens, ii. 340.

— height of stamens and results of pollina-
tion, ii. 405.

— in heterostyled flowers, ii. 396.

— in sprinkling flowers, ii. 333,

— in Willow-herb, ii. 354.

— nature and occurrence, ii. 291, 331,

— prevalence of, ii. 399.

— probable causes of prevalence in Alpine
and Arctic regions, ii. 401.

— statistics, &., ii. 399.

— wide geographical range, ii. 339.

Autonomous movements of plants, ii. 221.

Autumn leaves, causes of variegation, i. 486.

Autumnal tints, Arctic flora, i. 489.

—— in Europe and N. America, i. 487.

—— on Lake Erie, i. Pl. V.

Auxospore, of Diatoms, ii. 623.

Avena and Puccinia graminis, ii. 686.

— fruit-dispersal, ii. 843.

— pollination, ii, 142.

Avena compressa, leaf-folding, i. 340.

Avena elatior, course of pollen-tubes, ii. 408.

— — pollination, ii. 139.

— — spikelets, ii. 139.

—— stigma and germinating pollen-grains,

ii. 409.

Avena flavescens, arched leaf, i. 429.

Avenapl Imis, hical distr
and leaf-folding, i. 340.

Avena sativa, flower-opening constant, i. 559.

— — host of Ustilago segetum, ii. 675.

Averrhoa Carambola, leaf, diurnal positions,
i. 534,

Awn of Feather Grass, functions, i. 617.

— of Graminee, ii. 746.

Axillary buds, distribution, &e., ii, 29.

Axis, Ieaf-bearing, sorts of, i. 650.

— of inflorescence, i. 737.

Azalea, hair-like cuticular filaments, i. 310.

— ovary, ii. 76.

— pollen-tetrads, ii. 104.

— pollination, ii. 130.

— viscin of pollen-grains, ii. 101.

Azalea Indica, scentless, op —

Azalea pontica, scent, ii.

Azalea procumbens, i. soe oa, 490, 662.

— — autogamy, ii. 337.

— — flower, ii. 279.

—— rolled leaf, vertical section, i. 303.

— — stigma, ii. 282,

931

Azalea procumbens, weather and autogamy,
ii, 391.

Azolla, adaptation to change of habitat, i. 76.

— and Nostog, ii. 622.

— description, ii. 710, 711.

— swimming habit, i. 669.

Azygospores,in Mucorini, ii. 673,

B.

Bacharis, water-collecting and absorbing
organs, i. 232,

Bacillariales, description, ii. 625.

-— group of Thallophyta, ii. 620.

Bacillus, i. 263,

Bacillus Amylobacter, fermentation, ii. 623,

— — supposed fossil remains, ii. 625.

Bacillus amylovorus, canker on fruit-trees,
if. 523.

Bacillus Anthracis, cause of anthrax, ii, 624.

— —'shape of, i. 163.

Bacillus lacticus and souring of milk, ii, 623.

Bacillus subtilis, cilia, ii. 623.

Bacteria, action on blood, i. 167.

— as cause of disease, i. 163,

— conditions of life, i. 506.

— description, ii. 622.

— dispersion, i. 263.

— evidences of antiquity, ii. 624.

— fermentative action, i. 505.

— general characteristics, i. 161.

— means of distinguishing, i. 163.

— movements and cilia, ii. 623.

— nature of, i. 505.

— putrefactive, beneficent action, &c., i. 264.

— —in water basins, of Dipsacus, i. 242.

— saprophytic, effect on substratum, ii. 623.

— symbiosis with root-fibres, ii. 521.

Bacteria-rods, of Beggiatoa, i. 105.

Bacterium aceti, ii. 624.

—— activity, i. 506.

Bacterium termo, i. 263.

Balanophora, replaces Langsdorfia and
Scybalia in eastern hemisphere, i. 189.

—seeds, development, inception of infio-
rescence, &o., i. 190.

Balanophora dioica, widely distributed in
the Himalaya, i. 190.

Balanophora elongata, prevalence in Java,
collected for its wax, i. 190,

Balanophora fungosa, discovery and distri-
bution, i. 190.

Balanophora Hildebrandtii, i. 189.

Balanophora involucrata, hosts, i. 190.

Balanophoracew, i. 762.

— African species, fewness of, i. 196,

— anthocyanin, i. 483.

— colour and odour, ii. 197.

— embryo, i. 596; ii. 450.

— European genus, i. 198.

— features used for classification, i. 186.

— formerly d ibed as fungi,
about, i. 190.

— genera, i. 186.

— geographical distribution, i. 186,

— habitat, i. 186.

— nature of ‘as ii. 199.

— ovule, ii.

er ie i 59) 191, 195.

— scaly stems, i. 652.

—seed, embryo, germination, &., i. 188,

Balanophorales, ii. 762.

Balanophorin, wax-like substance of Langs-
dorffia stem, i. 188,

Ballistic fruits, ii. 840.

Ballota, seed protection, ii. 446.

Ballota nigra, autogamy, ii. 364.

Balsam. See Impatiens.

Balsam, Yellow. See Impatiens noli-tangere.

Balsam and transpiration, i. 461.

— excretion of capitate hairs, composition,
restrictive of transpiration, i. 312.

—name given to varnish-like substance
excreted by certain leaves, i. 237.

Balsaminea, extra-floral nectaries, ii. 232,

Baltic flora, colour percentages, ii, 182.

932

Bamboo. See Bambusa.

— type of culm, i. 714.

Bamboo-forest, ii. 890.

Bambusa, habit of growth, ii. 746.

—in Java, i. 713.

— leaf, vertical sections, i. 296.

— peg-shaped projections of cuticle, i. 310.

— protection of stomata from moisture, i. 294.

— reserve-buds, ii. 32.

— venation, i. 633.

Bambusa nigra, mechanical tissue arrange-
ment, i. 731.

Banana, germination, i. 604.

— leaves of, structure in relation to transpi-
ration, i. 288.

— sheltering of pollen, ii. 108.

— venation, i. 634.

Bangia, where thrives best, i. 105.

Banisteria, fruit, ii. 428.

— pollen-grains, ii. 99.

Banisteria Si iensis, seed-di ii.

853.
Banksia, follicles, ii. 430.
— vertical leaf-blades, i. 336.
Banksia ericifolia, inflor
spike, ii. '751.
Banksia ericoides, style and stigma, ii. 752.
Banksia littoralis, single flower, ii. ‘751.
—— style and stigma, ii. 752.
Banksia serrata, fruiting branch, ii. 429.
Banyan-tree. See Ficus Indica.
Baobab. See Adansonia.
Baptisia australis, colour-contrast of flower,
ii. 190.
Barbareea vulgaris, and galls of Ci

and fruiting

yia

INDEX,

Basella alba, pollen-grains, ii. 99.

Basidia, of Atcidia, ii. 22.

— of Agaricus, ii. 684.

— of Amanita, ii. 21.

— of Hymenomycetes, ii. 688.

Basidial layer of Amanita phalloides, ii. 685.
Basidiolict hical distribution

geog

and characters, ii. 695.
Basidiomycetes, i. 159; ii. 21, 606.
— basidia, ii. 20.
— certain, on Populus, i. 256.
— characteristics, ii. 684.
— fermentation, i. 505, 508.
—suppression of teleutospore in most, ii.

— various, ii. 685.

Basidiospore, of Hymenomycetes, ii. 688.
Basidiosporee, ii. 606.

Basidium, nature of, ii. 20,

— of Hemibasidii, ii. 675.

Basil. See Ocymum.

Basins, water-collecting, position, i. 240.
Bast, i. 208.

— hard, function, i. 469.

— — in Scoparium, i. 331.

— — in switch-plants, i. 426.

— soft, constituents, i. 469.

Bastard Palm. See Mclittis,

Bast-cells, functions, i. 468,

Bast-islands, i. 477.

Bast parenchyma, i. 469.

Bast-tube, i. 469.

Bast-vessel, i. 469.

Batrachium, section of R lus, ii. 505.

Sisymbrii, ii, 545.
Barbed bristles, Opuntia buds, i. 446,
— fruits, ii. 870.
Barbs, i, 439.
Barbuila, absorptive felt, i. 86.
— folding of leaf, i. 346.
— phyllotaxis, i. 408.
— transpiring cells, i. 278.
Barbula aloides, absorptive mechanism of
leaf, i. 218,
— — assimilating plates, ii. 702.
— — plates of cells, ii. 697.
Barbula ambigua, absorptive mechanism of
leaf, i. 218.
Barbula fragilis, propagation from leaves, ii.
458.

Barbula muralis, collection of dust, i. 266.

Barbula recurvifolia, parthenogenesis, ii. 464.

Barbula rigida, absorptive mechanism of leaf,
i, 218.

Bardfield Oxlip. See Primula elatior.

Bark, application of term, i. 719.

— as nutrient substratum, i. 106.

—kind of, affected by Aroids and Orchids,
i. 108.

— protection by, i. 476.

— sorts of, i. 719.

Barley. See Hordeum vulgare.

Barley-corns, germinating, heat of, i. 497.

Barriers to seed-dispersal, i. 879.

Bartsch, naturalist, &., i. 139,

Bartsia, i. 180.

— absorbent cells, i. 766.

— capturing apparatus, i. 137.

— distribution, appearance, habitat, &c., i.
139,

— hibernation, i. 140,

— nectary, ii. 174,

— parasitic, i. 176.

— pollination, ii, 129.

— sticky stigmas, ii. 282.

— venation, i. 631.

Bartsia alpina, absorptive cells and food-

absorption, i. 114,
— — anthocyanin, i. 522.
—-—arctic perennial member of Rhinan-
th ers ; half. itic, half-

saprophytic, &., i. 180.
— — geitonogamy, ii. 331.
— — pollen-sprinkling, ii. 272.
—— threefold mode of food-at

om

Batract mum, epiphytic, i. 161.

— structure, i. 590.

Bauhin, Historia plantarum, ii. 1.
Bauhinia, movements of cotyledons, i. 532.
Bauhinia anguina, ribbon-shaped stem, i.

Bauhinia armata, pollen-grain, ii. 100.

Bauhinia furcata, pollen-grain, ii. 100.

Bay Laurel. See Lawrus nobilis.

Bean, French. See Phaseolus vulgaris,

— starch, i. 459.

Bearberry, evergreen.
Uva- Orsi.

Bedeguar, and Rhodites Rose, ii. 552.

— gall of Rose-gall Wasp, ii. 537.

Bed-straw. See Galium.

Bee, colour preference, ii. 195.

— parthenogenesis, ii. 464.

— pollen-collector, ii. 167.

Beech. See Fagus.

Beech, American. See Fagus ferruginea.

Beech-gall Gnat. See Hormomyia agi.

Bees’-wax, scent, ii. 202.

Beetles and indoloid scents, ii. 207.

— sheltering in Composita, ii. 163.

Beet-root. See Beta.

Beggiatoa, movement of, i. 40.

Beggiatoa alba, reduction of sulphates, ii. 624.

Beggiatoa roseo-persicina, ‘‘ peach-mud”, ii.
623.

See Arctostaphylos

Beggiatoa versatilis, habitat, &c., i. 105.
Begonia, anthocyanin, i. 520.

— arrangement of stomata, i. 280.

— buds on leaves, ii. 41.

— hybrids, autogamous propagation, ii. 579.
— root-forming leaves, i. 772.

— roots from leaf-cutting, i. 88.

— ternary hybridization, ii. 560.

Begonia Dregei, leaf-mosaic, i. 420.
Begonia fuchsioides, scarlet flower, fi. 196.
Begoniaces, on trees, i. 106.

— saprophytic, on steep rocks, i. 108.
Belladonna Lily. See Amaryllis Bellad

Bent-grass. See Agrostis.

——Northern. See Elymus mollis,

Bentham and Hooker, Genera Plantarum,
ii. 604.

Benzoloid scent, ii. 199.

Berberidaces, anthocyanin, in adventitious
buds, i. 484.

— dehiscence of pollen-sacs, ii. 93.

— protogynous, ii. 312.

Berberis and Puccinia graminis, ii. 686.

— dehiscence of polleu-sacs, ii. 93.

— extirpation by law, ii. 687.

— irritable stamens, ii. 263.

— nectaries, ii. 264.

— phyllotaxis, i. 400.

— protection of pollen, ii. 119.

— radical shoots, ii. 27.

— scent, ii. 200.

— spines, i, 448.

— transference of pollen, ii. 264.

— venation, i. 630.

— weaving stem, i. 672.

Berberis vulgaris and Aicidium Magelhe-

nicum, ii. 527.

—— berry, ii. 427.

— — dates of flowering, i. 519.

— — spines, i. 449.

— — therma] constants, i. 559.

Bergamot Orange, reputed hybrid, ii. 569.

Bergenia crassifolia, elevation and colora-
tion, ii. 511.

Berries shrivelling through loss of water, i.
216.

Berry, nature of, ii. 427.
—of Mistletoe, germination experiment, i.
205.

Beta, germination constant, i. 558,

— grooved leaf-stalk, i. 95.

Betel Pepper. See Piper Betle.

Betula, amount of pollen, ii. 151.

— avoided by Mistletoe, i. 205.

— chalazogamic fertilization, ii, 412.

— flowering, ii. 150,

— foliage-leaves, i. 92.

— from chalk, ii. 613.

— pollen storing and dispersion, ii. 148.

— pollination, ii. 133.

— protection of pollen, ii. 119.

— protogynous, ii. 313.

— storage of pollen, ii. 94.

— thin places of pollen-grain, ii. 102.

Betula alba, i. 721.

——and B. nana, hybrid of, ii. 586.

— — bark, i. 720.

—— catkins, ii. 759.

— — mite-galls, ii. 529.

— — similarity to young B. verrucosa, ii. 514.

Betula alpestris, hybrid, ii. 586.

Betula carpatica, mite-galls, ii. 529.

Betula nigra, i. 488.

Betula papyracea, i. 488.

Betula verrucosa, and Exoascus turgidus,
ii, 527,

—-—difference between young and old
plants, ii. 514,

— — normal and sucker leaves, ii. 515.

— — seed-dispersal, ii. 853.

Betulaces, chalazogamic fertilization in, il.

412.

Beverages, alcoholic, i. 507.

Bhotan Pine. See Pinus excelsa.

Bideus bipinnata, hooked fruit, ii. 871.

Bidens cernua, and flooding by rivers, ii. 500.

Biennial plant, nature of, i. 658.

— plants, light and growth, experiments, ii.
508.

— — of Medit peculiarity, i. 319.

Bell-flower. See Campanula.

Bellidiastrum, autogamy, ii. 359,

— flowers after pollination, ii. 286.

— hermaphrodite and pistillate flowers, ii,
296,

Bellidiastrum Micheli, dichogamy, ii. 312.

Bellis, opening of flowers and growth, ii. 220,

— protection of pollen, ii. 120, 127,

138.

Bellis , athe in, i, 523; ii, 220.
Beloperone involucrata, scarlet flower, ii, 196,

Bignonia, clinging roots, i. 754.

— seed-dispersal, ii. 852.

Bignonia argyro-violaces, peculiarity of
climbing, i. 706.

— — Rio Negro, i. '709.

Bignonia capreolata, tendrils, i. 699.

Bignonia unguis, i. 706,

Bignonia venusta, hooked tendrils, i. 698

Bignoniaces, ii. 771.

— climbing roots, i. 702,

Bignoniacem, peculiarity of climbing, i. 706,

— scarlet flowers in, ii. 196.

Bilberry. See Vacciniwn uliginosum, Vac-
cinium myrtillus.

eee protective water-receptacles, ii.

Bindweed. See Convolvulus,

Bindweeds, S. Europe, silkiness, i. 320.

Biological importance of Chlorophycete, ii.627.

Biorhiza aptera, gall on oak-root, ii. 541.

Birch. See Betula.

ie and Firs, struggle for existence, ii.
514.

Birch-tree, bulk compared to volume of solid
and gaseous nutritive space, i. 259.

Bird-lime, from Viscum album, i. 329.

Birds, dispersal of plants, i. 205, 463; ii. 863.

‘ Bird’s eyes”, cause of, ii. 35.

Bird’s-foot Trefoil. See Lotus.

Bird’s-nest Orchis. See Neottia Nidus-avis.

Birthwort. See Aristolochia Clematitis,

Biscutella laevigata, ash of, i. 69.

Bistort. See Polygonum Bistorta.

Bitter Orange. See Citrus Aurantium.

Bitter-sweet. See Solanum Dulcamara

Bitter Vetch. See Orobus,

Bixa Orellana, flower-bud, ii. 776.

— — flowers and fruit, ii. 442, 444.

Bizzaria, hybrid orange, ii. 569.

Black Forest, Silver Firs with Mistletoe, i.
205.

Black Grouse. See Tetrao tetriv.

Black Pine district, Wiener Wald, Mistletoe
on Corsican Pine, i. 205.

Black Poplar. See Populus nigra.

Blackwellia, pollen-grains, ii. 99.

Bladder-campion. See Silene inflata.

“Bladder-plums ”, cause of, ii. 524.

Bladder-senna. See Colutea arborescens.

Bladders, of Sea-wracks, Tapa, i. 425.

— of Utricularia, size, shape, &c., i.121.

Bladderworts. See Utricularia.

Blastophaga Brasiliensis and Ficus, ii. 162.

Blastophaga grossorum and Ficus Carica, ii.

161.

—— and gall-flowers of Ficus Carica, ii. 540.

— — fertilization of Ficus, ii. 157.

Blechnum, fronds, ii. 12.

— protection of sporangia, ii. 13.

— sorus and indusium, ii. 706.

Blechnum Spicant, dimorphic fronds, ii. 476.

—— situation of stomata, i. 293.

“Blendlings”, result of crossing of “races”,
ii. 581.

Blood, and mould cells, i. 507.

— nutrient medium for bacteria, i. 162.

Blood-corpuscles, red, ii. 624.

“ Blood-portent”, ii. 623.

Bloodwort. See Sanguinaria Canadensis.

Bloom, nature of, i. 291, 462.

Blossom, nature of, ii. 71.

Blossoming, and altitude, i. 526.

— and geographical position, i. 565.

— comparative table, i. 566.

— of sea, i. 389.

— order of, i. 739.

— twice in one year, i. 564.

Blue, colour of spring flowers, ii. 194.

— true colour of sea-water, i. 389.

Blue Moulds, ii. 677.

Blue Mountains, Jamaica, abundance of

Ferns, Mosses, and Liverworts, ii. 457.

of water, explanation, i. 389.

Blue pi t, chl hyll prc i i

Bocconia, stamen-filaments, ii. 88, 183,

Bocconia Japonica, pollen discharge, ii. 145.

Bock, Hieronymus (1498-1554), i. 4.

—— and propagation of Ferns, ii. 8.

— — herbal of, i. 5.

Boeehmeria, cause of white spots on leaves
i, 285.

Boehmeria nivea, bast-cells, i. 725.

Bog-bean. See Menyanthes trifoliata.

Bog-moss. See Sphagnum.

Bog-rushes. See Schenus.

Bog-whortleberry. See Vaccinium wligi-
nosum.

PR)

INDEX,

Bolbophyllum Beccarii, nature of scent, ii.
199,

Bolbophyllum minutissimum, main features
of, i. 299.

— — tuber, surface view and section, i. 300.

er Odoardi, tubers, leaves, i.

Boletus edulis, Pl. XIV., ii. 688.

— — appearanee, ii. 491.

— — respiration experiments, i. 498,

Boletus sanguineus, poisonous, i. 491.

Bombax, hairy seeds, ii. 855.

— prickles, i, 433.

Bombus lucorum, pollination of Epipogium,
ii. 225, 257. ‘

Bonapartea, leaf-teeth and termination, i.
438.

Bonds of union, chemical, i. 453, 454,

Bonifacius, St., i. 539.

Boodlea, thallus, ii. 646.

Boraginacee, ii. 771.

— autogamy in, ii. 367, 378,

— cross-fertilization in, ii. 301, 222.

— dichogamy in, ii. 311.

— floral change of colour, ii. 191, 194.

— heterostyly in, ii. 302, 398.

— hybrids few among, ii. 585.

— nectaries, ii. 174, 181.

— pollen and probosces of insects, ii, 248,

— pollen-grains, ii. 97, 99.

— pollen-sprinkling in, ii. 275.

— protection of pollen, ii. 118,

— protogyny in, ii. 310.

— venation, i. 630.

— why named, pointed bristles, i. 441.

Borago, cotyledon bristles, i. 623.

— nectary concealment, ii. 181.

— protandrous, ii. 311.

Borago officinalis, colour-contrast of flowers,

ii. 189,

—— cotyledons, i. 621.

— — flower, ii. 275.

—— pollen-grains, ii. 98.

—— pollen-sprinkling apparatus, ii. 275.

Borassus, geographical distribution, ii. 740.

Borassus flabelliformis, i. Pl. VIII.

— — height, i. 712.

Bordered pits, nature and function, i. 277.

— — structure, i. 45.

Bornet and symbiosis in lichens, ii. 692.

Botanists and general principles of classifica-
tion, ii. 607.

Botany, descriptive, scope of, i. 15.

— discussion of terminology, ii. 4.

— German fathers of, i. 4.

— ‘the loveliest of sciences”, i. 6.

Botrychium, frond, ii. 709.

— spore-dispersal, ii. 814.

Botrychium lanceolatum, ii. 707.

— — dimorphic fronds, ii. 11.

— — sporangia, ii. 12.

Botrychium Lunaria, habitat, i. 112.

Botrydiacez, ii. 642.

Botrydium, cilia of, i. 29.

— life-history, ii. 642.

— reproduction, ii. 482.

Botrydium granulatum, habitat, ii. 642.

Botryococcus, life-cycle, ii. 636.

Botrytis, fermentative action, i. 508,

Botrytis cinerea, i. 263.

Bottle-gourd. See Lagenaria.

Bouchea coluteoides, sticky foliage, ii. 237.

Boundary-line, absence of, between plants
and animals, i. 54,

Bovenia, Australia, ii. 720.

Bovista, ii. 690.

Boyle’s law, i. 571.

Brachydodromus, venation, i. 630.

Brachypodium, pollination, ii. 142.

Brachypodium sylvaticum, arched leaf, i.

429,

—— venation, i. 634.

Bracken Fern. See Pteris aquilina.
Bract, application of term, i. 641.

— colour, ii. 183, 187.

— honey-protection by, ii. 238.

— nature of, i. 737

933

Bract, secretion of honey, ii. 173.
Bractea. See Bract.
Bracteoles, y in fruit-formati ii,
433.
Bract-scale, of Abies pectinata, &c., ii. 441,
21,

721,
Bradypus tridactylus, and Trichophilus, ii.
627.

Bramble. See Rubus fruticosus.

Branch, curvature and light, i. 416.

— direction and light, i. 414.

— form and position of transpiring, i. 325.

— long and short, i. 597, 650.

— nature of, i. 591.

— of Pinus Pumilio, ii. 722.

Branching and inflorescence, i. 749.

Branch-tendrils, morphology, i. 693, 694.

Brassica, siliquas, ii. 431.

Brassica alba, unequal cotyledons, i. 622.

Brassica oleracea, epiphyllous buds, ii. 43.

— — root-galls, ii. 521.

—— stomata, i. 280.

— — wax on leaves, i. 292.

Brassica Rapa rapacea, root, i. 760.

Braun, Alexander, reclassification of Mono-
chlamydew, ii. 616.

— — system of classification, ii. 605.

Braya alpina, autogamy, ii. 335.

— — guides to honey, ii. 248.

Bread-fruit. See Artocarpus incisa.

Break back, use of term, ii. 570.

“Breaking”, from roots, ii. 27.

Breathing and living, synonymous, i. 493.

Bristle Ferns. See Hymenophyllacee.

Bristles, i. 439.

— barbed structure, i. 440.

— for retention of salt incrustations, i. 237.

— of Aldrovandia leaf, i. 152.

— of Dionza leaf, i. 150.

— stinging, structure and function, i. 441.

Briza maxima, seed-dispersal, ii. 854,

Briza media, anthocyanin in glumes, i. 522.

—— pollination, ii. 142.

Broad-bean. See Vicia Faba.

Brome-grass, See Bromus.

—— False. See Brachypodium.

Bromeliacez, centripetal inflorescences, i.

738.

— coloured bracts in, ii. 184.

— distinctive characters, ii. 734,

— epiphytic, i. 77, 106.

— furfuraceous appearance, i. 324.

— geographical distribution, ii. 734.

— habitat, i. 438.

— organic remains in cisterns of, i. 242.

— pollen-grains, ii. 102.

— scarlet flowers in, ii. 196.

— tropical epiphytic, thick cuticle, i. 309.

— water-receptacles, i. 156.

— — — absorptive cells, i. 231.

Bromeliex, characteristics, ii. 734.

Bromine, in marine plants, i. 68.

Bromus, and cluster-galls, ii. 547,

Brongniart, ii. 603.

Brood-bodies, and constancy of form, ii. 594,

— — hybrids perpetuated by, in Roses, ii. 555.

—— importance for propagation, ii. 70.

—— in ovule, resemble normal embryos, ii.
469.

—— nature of, ii. 6.

— — of Mosses, ii. 702.

—— possible origin from ooplast, ii. 467.
—— potential, ii. 46.

Broom. See Spartium scoparium.
Broom-rape. See Orobanche.

Broussonetia papyrifera, dicecious, ii. 299.

— — ejection of pollen, &c., ii. 137.

—— normal and sucker leaves, ii. 515.

—— stigma, ii. 251.

—— twig, i. 418.

Brown, on cell, i. 14.

Brownea coccinea, &c., scarlet flower, ii. 196,
Brugmansia, Borneo and Java, flowers, i.

- geographical distribution, i. 204.
— pollen-grain, ii. 98, 102.
— protection of pollen, ii. 118.

934

Brugmansia Tipellii, on Cissus root, i. 202.

Brunfels (1495-1534), i. 4.

Brunnichia africana, pedicel and fruit, ii. 435.

Brunoniacex, ii. 765.

Bryacezx, general description, ii. 701.

— seta, ii. 702.

— sexual organs, ii. 702.

Bryonia, i. 698.

— filament of stamen, ii. 88.

— tendrils, i. 696.

Bryonia dioica and Andrena florea, ii. 206.

— — stamen, ii, 87, 90.

Bryophylium calicinum, epiphyllous buds,
ii. 40, 41.

Bryophyta, ii. 617, 696.

— compared with Pteridophyta, ii. 704.

— of Brann, ii. 605.

Bryopsidacez, description, ii. 645,

Bryopsis, ii. 645.

— colonies, i. 585.

— differentiation of thallus, ii. 619.

— gemmation, ii. 575.

Bryum, ii. 480.

Bryum alpinum, parthenogenesis, ii. 464.

Bryum cespitosum, ii. 700.

—— peristome, &c., ii. 15.

— — reproductive organs, ii. 15.

Bryum concinnatum, vegetative propaga-
tion, ii. 458.

Bryum Duvalii, parthenogenesis, ii. 464.

Bryum Reyeri, vegetative propagation, ii.
458.

Buckbean. See Menyanthes trifoliata.

Buckthorn, Sea. See Hippophaé.

Buddha, and Sacred Fig-tree, i. 757.

Budding, compared to parasitism of Loran-
thus on Oak, i. 215.

— modus operandi, i, 214.

— perpetuation of crossings by, ii. 556.

Bud-gall, nature of, ii, 542.

—— on Thymus Serpyllum, ii. 531.

Bud-like offshoots, replacing flowers and
fruits, ii. 460.

Buds, adventitious, development of, ii, 26.

-— — of Mistletoe cortical roots, i. 209.

— and cold, i, 552.

— axillary, distribution, &., ii. 29,

— cauline, ii. 28.

— considered as brood-bodies, ii. 6.

— dormant, longevity, ii. 36.

— due to wounds, ii. 29.

— epiphyllous, ii. 37.

-~ extra-axillary, ii. 28.

-- first, of Orobanche, i. 184.

-- hibernating, in Aldrovandia, i. 152.

-- importance of situation, i. 596,

-- modes of breaking through soil. i. 639.

~ of Langsdorfiia, i. 186.

— of Rafflesiaceze, development, i. 200.

-on Fern fronds, ii. 39.

~— on floral-leaves, fi. 44,

— on foliage-leaves, ii. 41.

—on roots, i. 766.

— on scale-leaves, ii. 44,

-— position of unfolding leaves, i. 538.

— radical, ii. 27.

— respiration, i. 494,

— resting of, i. 563.

— structure, i. 591.

— subterranean, i. 651,

— — of Bartsia, i. 137, 139.

— winter, of Utricularia, i. 120.

Bud-scales, stipular, i. 637.

— structure and function, i. 623.

Bugwort. See Cimicifuga fetida.

Building materials of plants, i. 456

Bulb, application of term, i. 650.

— propagation of hybrids by, ii. 556.

— protective scales, i. 653.

— resting, of desert perennials, i. 556,

— scale-leaves, i. 624.

Bulbs, dispersed by root-shortening, ii, 831.

Bulbil, nature of, i. 591.

— of Poa alpina, &., mode of formation, ii.
454.

— of Psilotum, ii. 715.

— replacing flowers and fruits, ii. 445, 461.

INDEX.

Bulbocheete, structure, ii. 651.

Bulbocheete parvula, home of, i. 105.

Bulbocodium, flower, ii. 729.

— protection of pollen, ii. 125.

Bulbus, application of term, i. 624.

Bulgaria inquinans, habit and habitat, ii. 682.

Bulgaria polymorpha, habitat, i. 118.

Bullace. See Prunus insititia.

Bulrush, Lesser. See Typha.

Bundle-sheath, i. 471.

Bunium, germination, i. 622.

Buphthalmun, flowers, sorts of, ii. 296.

— geitonogamy, ii. 322.

Buphthalmum grandiflorum, pollen-grains,
ii. 99.

Bupleurum, coloured bracts, ii. 183.

Bupleurum falcatum, venation, i. 632, 633.

Bupleurum verticale, position of leaves, i.
337.

Burmanniacex, ii. 738.

Burnet-moths and honey scent, ii. 207

Burnet Saxifrage. See Pimpinella.

“Burning” of plants, i. 539, 553, 556.

Bur-reed. See Sparganium.

Bush-plants, i. 432.

Butcher’s-broom. See Ruscus.

Butomacee, ii. 739.

Butomus, anthocyanin, i. 520.

— germination, i. 604.

-- integument of ovule, ii. 81.

—no special arrangement for rain-water
conduction, i. 98.

— ovary, ii. 75.

— protective isolation by water, ii. 234.

Butomus umbellatus, flower, enneandria, ii.

289.

— — hermaphrodite, ii. 296.

——ovule, &c., ii. 78.

— — placentation, ii. 739.

Butter-bur. See Petasites.

Butterflies and pollination, ii. 156.

Butterfly Orchis. See Habenaria,

Butterwort. See Pinguicula.

Buttress-roots, i. 756.

Butyric acid, i. 463.

— — fermentation, ii. 623.

Buxbaumia aphylla, simplicity of form, ii.
704.

Buxus, honey, ii. 173.

— pollination, ii. 138,

— protogynous, ii. 313,

Bypblis, i. 148.

Byblis gigantea, carnivorous in minor de-
gree, i. 156.

©.

Cabbage. See Brassica oleracea,

Cabbage-white Butterfly. See Pieris Bras-
sice, ii. 672.

Cabomba aquatica, heterophyllous, i. 668

Cacalia, autogamy, ii. 363.

— pollination, i. 740.

Caccinia, cotyledon bristles, i. 623.

Caccinia strigosa, hooked fruit, ii. 871.

Cachrys, seed protection, ii, 450.

Cachrys alpina, rolling fruits, ii. 849.

Oachrys spinosa, ‘‘thistle-leaves”, i. 438,

Cactacez, calcium oxalate crystals, i. 570.

— course of pollen-tubes, ii. 410,

— cross-fertilization in, ii. 301.

— on trees, i. 106,

— ovary, ii. 77.

— protogyny in, ii. 310,

— spines, i. 446.

Cactales, ii. 786.

Cacti, geographical distribution, i. 327, 330.

— propagation of hybrids, ii. 556.

— size of flowers, ii. 185.

Cactiform plants, thick cuticle, i. 309.

— stem, i. 712.

Cactus, nectary, ii. 174,

— perianth-leaves, i. 641.

Cadia varia, flower, ii. 779.

Cesalpinex, from chalk, ii, 613.

— scarlet-flowered genera, ii, 196.

Caladium, i. 94.
Calamagrostis, boring runners, i. 516.
— hybrids in, ii. 583.
— pollination, ii, 142.
Calamagrostis Epigeios, seed-dispersal, ii.
858.
Calamagrostis Halleriana, arched leaf, i. 429.
Cal ize, fossil Equisetales, i. 636; ii. 713.
Calamintha, anther, ii. 90.
— distribution of sexes, ii. 298.
— hybrids, ii. 585.
— seed protection, ii. 446.
Calamus, ii. 741.
Calamus angustifolius, vessels, i. 362.
Calamus extensus, shoot apex and inflor-
escence, i. 676.
Calandrinia, allurement by petals, ii. 171.
Calandrinia compressa, autogamy, ii. 346, 391.
— — opening and closing, ii. 212.
——stamen, ii. 91.
Calcareous crust of hydrophytes preserved,
i 261.
Calcareous Floridez, fossil remains, ii. 614.
Calcareous strata, formation by plants, i. 261.
Calceolaria, hybridization and flower colours,
ii. 568.
—nectary, &c., ii. 228.
— sheltering of pollen, ii. 110,
Calceolaria amplexicaulis, &c., nectary, ii.178.
Calceolaria Pavonii, flower and autogamy,
ii. 380.
——stamen, ii. 91.
Calceolariz, pollen sprinkling in, ii. 274.
Calcification of hairs, i. 441.
Calcite, crystalline forms, ii. 493.
Calcium, how introduced, i. 67.
— in ash of plants, i. 66.
1 t by
— salts, i. 274.
Calcium carbonate, conversion into bicar-
bonate, i. 257.
—— crystal forms, ii. 493.
— — protective incrustation over absorption-
cells in Saxifraga Aizoon, i. 234.
Calcium chloride, in salt incrustations of
leaves, i. 236,
— — seed desiccation by, i. 554,
Calcium nitrate, liberation of nitric acid, i.
458.
Calcium oxalate, crystals in plants, i. 570
— — excess thrown off with leaf, i. 358,
— — formation of, i. 67. 7
—— in autumn leaves, i. 485.
Calcium sulphate, as food-salt, i. 67.
—— source of sulphur, i. 458.
Calendula, distribution of sexes, ii. 297.
— geitonogamy, ii. 321.
— imperfect flowers, ii. 295.
— opening of flowers and growth, ii. 220.
— protection of pollen, ii. 115.
Calendula arvensis, &c., resistance to cold,
ii. 489,
Calendula officinalis, dichogamy, ii. 312.
Calendula pluvialis, anthocyanin in florets,
ii. 220.
Californian Mammoth Tree,
gigantea, ii. 725.
Calla palustris, i. 708.
— — creeping stem, i. 662; ii. 745.
— — dehiscence of pollen-sacs, ii. 92.
—— geitonogamy, ii. 326.
—-— hermaphrodite and staminate flowers,
ii. 297.
—— stamen, ii. 91.
Calliandra, pollen-chambers, ii. 90.
Callidina symbiotica, on Frullania, i. 255; ii.
698.
Calliphora and indoloid scents, ii. 207.
Callistemon, coloured stamen-filaments, ii.
183.
— inflorescence, i. 738.
— unprotected pollen, ii. 107.
Callitriche, fruit, and section, ii. 427.
— leaf rosettes, i. 412.
— leaves and light, ii. 505,
— nut, ii. 429,
— pollen dispersion, ii, 105.

—r

i. 70.

See Sequoia

Caliophora utilis, Amazon, latex, i. 470.
Calluna, pollen tetrads, ii. 97.
Calluna vulgaris, and grazing animals, i. 445,
—— distribution and range, i. 305, 526.
~— — flower-opening constant, i. 559.
—— pollination, ii. 129,
— — sheltered pollen, ii. 107.
Callus, buds from, ii. 30.
— formation in leaf-cuttings, ii. 42.
Calothamnus, unprotected pollen, ii. 107.
Caltha, trabecul in palisade cells, i. 374.
Caltrop. See Tribulus.
Calycanthus, flower, icosandria, ii. 293.
— fruit, ii. 434.
— pollen-grains, ii. 99.
— scent, ii, 200.
Calyceraces, ii. 765.
Calyciflorze, of De Candolle, ii. 603.
Calyptra, of Bryum, &c., ii. 479, 700.
Calyx, accessory in fruit formation, ii, 433.
— estivation, ii. 210.
—and autogamy, ii. 366.
— application of term, i. 641.
— inflated, protection by, ii, 238.
Cambium, i. 469, 476.
— in Isoétes, is.717.
— of Laminaria, ii. 662.
Camelina sativa, gall-mites and floral meta-
morphosis, ii. 548.
— — germination constant, i. 558.
Camellia, and ancient crossing, ii. 555.
— double hybrids, ii. 576.
— host of Mycoidea, ii. 653.
Camellia Japonica, scentless, ii. 209.
Campanula and Arnica Montana, &c., colour-
contrast, ii, 193.
— and insect visits, ii, 222.
— autogamy, ii. 361.
— bell, as insect shelter, ii. 163.
— cleistogamy, ii. 393.
— diversity of pollen protection, ii. 128.
—nectary concealment, ii, 181.
— pollen-grains, ii. 100.
— protection of pollen, ii. 128, 118, 113
— seed-dispersal, ii. 447.
— storing of pollen, ii. 359,
Campanula barbata, autogamy, ii. 362.
—-— protection of pollen, ii. 118.
—— temperature within flower, i. 501.
Campanula carpatica, autogamy, ii. 362,
Campanula persicifolia, anthocyanin, i. 520.
—— flower and autogamy, ii. 360.
—-— pollen-grains, ii. 99.
sa patula, protection of pollen, ii.
1A.
Campanula pusilla, elevation and coloration,
ii, 511
—— leaf-mosaic, i. 410.
— — leaf-rosette, i. 411.
Campanula pyramidalis, autogamy, ii. 362.
Campanula rapunculoides, autogamy, ii. 362.
— — capsules in dry and wet weather, ii. 448.
Campanularotundifolia, protection of pollen,
ii, 128.
Campanula spicata, autogamy, ii. 362.
— — protection of pollen, ii. 113,
Campanula Trachelium, autogamy, ii. 363.
— — foliaceous stamen, ii. 86, 88.
— — white and blue-flowered individuals, ii.
193.
Campanula Zoisii, pull of roots, i. 768.
Campanulaces, ii. 767.
— protandrous, ii. 312.
— storage of pollen, ii. 94.
Campelia Zanonia, root-hairs of, i. 224.
Camphora officinalis, or C. officinarum, dehis-
cence of pollen-sacs, ii. 93, 753.
Camphor Tree. See Camphora officinalis.
Camponotus Atthiops and Jurinea Mollis, ii.
243.
Campylodiscus spiralis, ii. 626.
C: lodromous tion, i. 633, 634.
Campylopus, vegetative propagation, ii. 816.
Campylopus fragilis, brood-body, ii. 23.
— — propagation from leaves, ii. 458.
Campylotropous ovule, i. 644
— seed, ii. 425.

INDEX,

Canadian Golden-rod. See Solidago Cana-
densis,

Canadian Lianes, i. 670.

Canal, in cell-wall, i. 45.

oe of neck of amphigonium, ii. 64,

Candles, made from Balanophoras, i. 190,

Cane-sugar, alluring, i. 461.

Canker, causes of various sorts, ii, 522, 523.

Canna, pollen-grain, ii. 100.

— starch, i. 459.

— venation, i. 634,

— water-absorption by seeds, ii. 426.

Canna indica, ii. 736,

Cannabinacer, ii. 758.

Cannabis, amount of pollen, ii. 151.

— bast-cells, i. 725.

— dioecious, ii. 299.

— pollination, ii. 133, 143.

Cannabis sativa, filament of stamen, ii. 88.

— — fruit-protecting glands, ii. 447.

— — germination constant, i. 561.

— — pollen-grains, ii. 98.

—— protogyny, ii. 313.

— — vitality of spermatoplasm, ii. 96.

Cannacew, ii. 599.

— floral characters, ii. 736.

— leaves and rain conduction, i. 94.

— pollen-grains, ii. 97.

Cantharellus cibarius, appearance, ii. 491.

— — edible, Pl. XIV., ii. 689.

Caoutchouc, source of, i. 756.

Cap, of Hymenomycetes, ii. 688.

— of moss sporogonium, ii. 15.

Cape, hairiness of plants, i. 317.

—heaths of, number and variety; other
plants with rolled leaves, i. 306.

— spiny plants, i. 438.

Cape bulbs, cross-fertilization, ii. 301.

Cape of Good Hope, flora comparable to that
of Baltic lowlands, i. 305.

Capercailzie. See Tetrao Urogallus.

Capillarity, and ascent of sap, i. 269, 270.

Capillary action of porous cells in Leuco-
bryum and Sphagnum, i. 220.

Capillitium, mode of action, ii. 812.

— of Gasteromycetes, ii. 690.

— of Myxomycetes, ii. 619.

Capi cell, glandul: of Aldrovandia, i.
153.

— cells, secretory action in Pelargonium, &c.,
i. 229.

— galls on Prunus, ii. 532.

— hairs, advantage of, i. 230.

— — excretionof, restrictive of transpiration,

i. 312.

Capitula, of Helosis, i. 192.

Capitulum, i. 739.

— 1-flowered, i. 766.

— prevalence, i. 745.

Caprification, ii. 160-162.

Caprifoliacex, cross-fertilization in, ii. 301.

— geitonogamy in, ii. 325.

— protogynous, ii. 312.

Caprifoliales, ii. 763.

Caproic acid, ii. 202.

Capsella, pollen-grain, ii. 100.

Capsella Bursa-pastoris, galls on, ii, 525.

— — leaves and light, i. 410.

Capsella pauciflora, stem, i. 656.

Capsular envelope of spores in Floridez, ii.
62.

— fruits, ii. 431.

Capsule, inferior, dehiscence, ii. 79.

— nature of, ii. 430.

— of Bryacee, ii. 702.

— of Colchicum, ii. 729.

— of Lathrza and Orobanche, i. 181.

— of Marchantiacez, dehiscence ii. 697
— of Sphagnum cymbifolium, ii. 700.
— restricted sense, ii. 432.

Capsule-gall, ii. 539.

Capsules, seed protection and dispersal, ii.

Caragana, reserve buds, ii. 33.
Caragana microphylla, &c., stipular spines,
i, 448.

9385

Carbohydrate, conversion into albumen, i
457.

Carbohydrates, conducting tissues for, i. 479.

— formation of, i. 60, 456.

— oxidation, i. 378, 495.

— splitting up by Bacteria, i. 263.

Carbon, i. 258,

— chemical properties, i. 452.

— in albumen, i. 457.

Carbonate of lime. See Calcium carbonate.

Carbon-dioxide, i. 263.

— — absorption by cell-wall, conversion into
carbonic acid, i. 368.

—— in air, i, 79.

— — in nutrition, i. 60.

Carbonic acid, i. 235.

— — absorption by earth, &c., i. 83.

—— conduction by aqueous tissue, i. 330.

— — decomposition, i. 371, 455.

— — elimination by roots, i. 88.

— — evolution in fermentation, i. 506.

—— factors controlling absorption, i. 60.

— — food-gas, transmission, i. 367.

—-—Jin symbiosis of Hepatic with Roti-
fera, i. 255,

—— in water, effect, ii. 499.

—— reduction, and formation of carbohy-
drates, i. 378.

—— source of, for hydrophytes, i. 260.

— — source of, for lithophytes, &c., i. 61.

—— sources of, i. 83.

Cardamine, colour-contrast in inflorescence,

ii, 193.

— influence of gall-mites, ii. 550.

— rhizome and light, i. 484.

Cardamine alpina, autogamy, ii. 335.

—— food of grub of Pieris Callidice, ii.
488.

Cardamine amara, anthocyanin, i. 522.
—— habit and temperature, ii. 503.
Cardamine chenopodiifolia, cleistogamy, ii.
393.
Cara
453.
Cardamine impatiens, seed-dispersal, ii. 835.
Cardamine pratensis and cuckoo-spit, ii. 544.
— — artificially induced drooping, ii. 123
— — buds on leaves, ii. 41.
— — epidermal roots, i. 766.
—— flower, tetradynamia, ii. 292.
— — hermaphrodite, ii. 296.
—-— root-forming leaves, i. 772.
Cardamine trifolia, anthocyanin, i. 520.
Cardamine uliginosa, gall-mites and flower
metamorphosis, ii. 548.
— — vegetative propagation and its cause, ii.
459.

hirsuta, f tive perennial, ii.

Cardiospermum, tendrils, i. 694.
Cardopatium corymbosum, cotyledons in ger-
mination, i. 613.

—— germination, i. 611.

Carduus, hybrids, ii. 585.

— spinose leaves, i. 438.

Carex, ii. 719.

— hybrids in, ii. 583.

— pollination, ii. 133, 136, 142.

— protogynous, ii. 313.

— substratum, ii. 498.

— venation, i. 634.

Carex acuta, and cattle, i. 440.

Carex acutiformis, dichogamy and hybridiza-
tion, ii. 315.

Carex aterrima and CO. atrata, anthocyanin,
i. 522,

Carex Boenninghausiana, hybridof C. panicu-
lata x C. remota, ii. 586.

Carex canescens, &c., dichogamy and hybridi-
zation, ii. 315.

Carex curvula, habitat, i. 113.

Carex Davalliana, &c., dicecious, ii. 299.

Carex microglochin, hooked fruit, ii. 874.

Carex paludosa, leaf section, i. 295.

Carex pendula, protection of stomata from
mndisture, i, 295.

Carex stricta, barbs, i. 439.

—— protection of stomata from moisture,

i, 294.

936

Carex stricta, social form, ii. 748.

Carex vulgaris, seedlings, i. 607.

Carica Papaya, enzyme, i. 465.

Carinthe minor, pollen-grains, ii. 97

Carlina, spiny leaves, i. 438.

Carlina acaulis, anthocyanin, i. 522.

——as hygrometer and weather-glass, ii.

117.

— — coloured bract, ii. 183.

— — opening and closing, ii, 116.

—— pollen-grains, ii. 99.

— — protection of pollen, ii. 115, 117.

— — temperature within capitulum, i. 501.

Carmichelia australis, cladodes, i. 335.

Carniola, flora of, i. 6.

Carnivorous plants, movements, i. 140.

—— number of, classification of, i. 119.

— — spinous structures in pitfalls, i. 124.

— — with scale-like leaves, i. 135.

Carob. See Ceratonia Siliqua.

Carolina Allspice. See Calycanthus.

Caroway. See Carum carvi.

Carpathians, plants of, i. 316.

Carpel, morphology, ii. 89.

— of Cupressus, ii. 443.

Carpels, arrangement, &., i. 642.

— arrangement on receptacle, ii. 74,

— foliaceous, ii. 83.

— persistence, ii. 719.

Carpenter Bee and Spartium scoparium, ii.
267.

Carpet, type of community, ii. 889, 893.

Carpinus and gall-mites, ii. 529,

— bud-scales, i. 626.

—cupule, ii. 434,

— defoliation slow, i. 361.

— embryo-sacs, ii. 478.

— pollen-storing and dispersion, ii, 148,

— vernation, i. 350, 631.

Carpinus Betulus, ii. '759.

—— and Exoascus Carpini, ii. 527.

— — chalazogamic fertilization, ii. 412.

— — dimensions, i. 722.

— — fruiting branch, ii. 433.

— — height, i, 722.

—— pocket-galls, ii. 532.

Carpinus orientalis, seed-dispersal, ii. 854. |

Carpium, definition, ii. 47.

Carpophylla. See Carpels.

Carposporee, ii. 606.

Carpospores, of Coleocheete, ii. 654.

INDEX,

Caryophyllacez, protandrous, ii. 312.
— protandry and autogamy, ii. 336.
— stigmatic surface in, ii. 281.
— times of opening and closing, ii. 221.
Caryophyllinz, of Brana, ii. 605.
Caryopsis, nature of, ii. 429.
— of Gramines, ii. 746.
Caryota, caudex, i. 714.
— geographical distribution, ii. 740.
Caryota propinqua, i. 311.
— — fate of specimen cultivated at Vienna,
i. 310.
— — leaf-section, i. 312.
Casein, i. 458.
Cashew-nut. See Anacardium occidentale.
Cassia angustifolia, pod, ii. 431.
Cassia lenitiva, stamen, ii. 91.
Cassiope tetragona, rolled leaves, i. 304
Cassytha, i. 182, 687; ii. 752.
— affinities, i. 171.
— geographical distribution, i. 171.
— germination and mode of attack, i, 176.
— parasitism, i. 171.
— physiological roots of seedling, i. 750.
Castanea, cotyledons, i. 608.
— cupule, ii. 434.
— fertilization, porogamic, ii. 413.
— scent, ii. 200.
Cast: sativa,
560.
Castanea vulgaris, age, i. 720.
— — diameter, i. 722.
— — fruit protection, ii. 442, 445.
Castanospermum, seed-dispersal, ii. 837.
Casuarina, chalazogamic fertilization, ii. 412,
616.
Casuarina quadrivalvis, branch and cross
section, i. 299.
—— protection of stomata from moisture,
i. 298,
Casuarinez, Australian, switch-plants, i. 330,
376.

thermal cc

i. 559,

— chalazogamic fertilization, ii. 413.

— chlorenchyma, and stomates, i. 332,

— little shadow from, i. 336.

Catalpa, opening and closing of stigma, ii. 281.

— pollen deposition, ii. 280.

Catalpa syringzfolia, thermal constants, i.
559, 560.

Catananche, protection of pollen from rain,
ii, 112.

Carrion-beetles and Dr

Cat: he coerulea, duration of blossoming,

&e., ii. 165.

Carrion-flies, favourite colours and odours,
ii. 197.

Carrot. See Daucus Carota.

Cartharcus, preservation of colourin Egyptian
graves, i, 262.

Carthamus tinctorius, demonstration of irri-
gation, i. 96.

Carthusian Pink. See Dianthus Carthusian-
orum,

Cartilage, digestion of, by Pinguicula vul-
garis, i. 142.

Carum carvi, schizocarp, ii. 427, 430.

Caruncle, nature of, ii. 425.

Carya, mode of fertilization unknown, ii. 413.

Caryophyllaces, ii. 196.

— estivation in, ii. 210.

— autogamy in, ii. 335, 352, 355.

— capsules, ii. 432.

— carnivorous in minor degree, i. 155.

— course of pollen-tubes, ii. 410.

— crepuscular perfume, ii. 208.

— cross-fertilization in, ii. 307.

— distribution of sexes, ii. 298, 299,

— floral envelopes, ii. 749.

—gall-mites and flower metamorphosis in,
ii, 548.

— heterostyly in, ii. 398.

— hybrids among, ii. 584.

— insects and pollen, ii. 244.

— movements of stamens, ii. 250.

— nectaries, ii. 175, 176.

~— nocturnal flowering, ii. 154,

— pollen deposition in revolver-flowers, ii. 277.

— pollen-grains, ii. 99.

ii. 218.
Catapuit-fruits, ii. 840.
Catasetum, ii. 738.

Cataset’ tridentatum, di

linia, details, ii. 270.
—— pollination, flower and parts, ii. 269.
Caterpillars and Cordyceps, ii. 680.

— as hosts, i. 168.

— hosts of Entomophthorew, ii. 672.

— protection aguinst, ii. 445.

Cathartolinum, guides. to houey, ii, 249,

Catingas, of Brazil, i. 356.

Catkin, i. 739.

Cat’s-foot. See Gnaphalium dioicum.

Cattle, anthrax in, i. 163.

Cattleya, ii. 738.

Cattleya labiata, duration of flowering, ii, 214.

Caucalis daucoides, autogamy, ii. 342.

— — flowers, sexual conditions, ii. 296.

— — protogynous, ii. 311.

Caucasus, plants of, i. 316.

Caudex, i. 655, 710.

— characteristic examples, i. 712.

— thorns and leaf-sheaths, i. 714.

Caulerpa, habit, species, &., ii. 645.

— structure and light, i. 388.

Caul it Violas, cleist

Cauliflower, nature of, ii. 553,

Cauline buds, shoots, &c , ii. 28,

Caulis. See Stalk.

Caulis herbaceus, i, 715.

Caulis suffruticosus, i. 715.

Cauloma. See Caudex.

Caulomes, underground, of Saprophytes, and
food-absorption, i. 114.

of pol-

y, ii, 393,

Caulotretus, hosts of Rafflesiaceze in Venez-
uela, i. 200.

— undulation of stem, i. 735.

Cavanillesia tuberculata, Brazilian Catingas,
i. 656.

Cavern Moss. See Schistostega.

Cavities, grooves, &c., in leaves, for collection
of water, i. 230,

Caylusea, ovary, ii. 75.

Cecidium, proposed application of term, ii.
528.

Cecidomyia, escape of larve from galls, ii.
38,

— gall-gnats, ii. 534.

Cecidomyia Ar i
campestris, ii. 547.

Cecidomyia Asperule, galls on Asperula, ii.
545.

gall on Ar

Cecidomyia cerris, on leaf of Turkey Oak, ii.

i, galls on C ii.

Cecidomyia
546.

—— possibility of transmitting effects, ii. 554.

Cecidomyia Ericz, galls on Erica, ii. 547.

Cecidomyia Galii, galls on Galium, ii. 545.

Cecidomyia genisticola, galls on Genista
tinctoria, ii. 546.

Cecidomyia Loti, bud-galls on Lotus cornicu-
Tatus, ii. 544.

Cecidomyia phyteumatis, bud-galls on Phy-
teuma orbiculare, ii. 544.

Cecidomyia rosaria, cluster-galls on Salix, ii.
546.

Cecidomyia scoparia, ii. 547.

Cecidomyia Sisymbrii, galls on various Cru-
cifere, ii. 544,

Cecidomyia urtice, gall on nettle-leaf, ii. 534,

Cecidomyia Verbasci, bud-galls on Verbas-
cum, ii. 544.

Cecidomyia Veronice, galls on Veronica
chameedrys, ii. 546.

Cecidoses Eremita, escape of larva, ii. 539.

— — galls on Duvana, ii. 534, 537.

Cecropia peltata, myrmecophilous, ii. 233.

Cedrela, seed appendages, ii. 424.

Cedrela odorata, pollen-grains, ii. 99.

Cedrela Toona, ii. 423.

Cedrus, ii. 721.

Cedrus atlantica, ii. 725.

Cedrus Deodara, Asia Minor, ii. 725.

— — freezing, i. 546.

Cedrus Libani, ii. 725.

— — age and height, i. 722.

Celandine. See Chelidoniwm majus.

Celandine, Lesser. See Ranunculus ficaria.

Celastrinezs, aril in, ii. 425.

Celastrus, Brazilian, capsule-gall, ii. 539.

Celastrus scandens, weaving stem, i. 672.

Cell, laticiferous, i. 470.

— naked, unfortunate term, i. 26.

— observations of Brown and Mohl (1830-
1840), i. 14.

— original meaning, i. 22.

— partition-wall, i. 26.

— shapes, i. 374; cf. Pl. I.

— the, a minature chemical laboratory, i. 16.

— wall of, early views, i. 23.

Cell-aggregates, various comparisons of, i. 27.

Cell-cavities, ti bi i
i. 45.

Cell-chambers, i. 27.

Cell-complexes, sorts of, i. 586, 587.

Cell-contents, attraction of water by, i. 229.

Cell-division, i. 573.

—— details, i. 580 et seq.

— — in Spirogyra, ii. 657.

Cell-formation, free, nature of, i. 575.

Cell-membrane, a sieve, i, 57.

— — assumed structure, i. 57.

— — correct view of, i. 14.

— — diffusion through, i. 59.

— — elastic, i. 59.

—— imbibition of water, i. 58.

— — modifications of, i. 43,

— — of Diatoms, i. 40.

— — penetrability of, i. 58.

— — permeability in absorption-cells, j. 226.

Cell-membranes, action of iodine on, i. 73.
~—— behaviour in absorption, i. 85.
— — dead, swelling of, and retention of mud
particles, i. 267,
Cell-nucleus. See Nucleus.
Cell-plate, in cell-division, i, 581.
Cells, absorptive. See Absorption-cells.
—air-containing, as a protective covering,
experimental proof, i, 314.
— all from one, i. 48.
— capitate, of Lathraa, i. 137.
— chlorophyll containing, of Leucobryum
and Sphagnum, i. 219,
— development of new, i. 27.
— epidermal silicified, i. 329.
— glandular, of Aldrovandia, i. 153.
— — of Cephalotus pitchers, i. 132.
— many-armed, of mesophyll, i. 279.
— permanent, i. 582.
— pitted, reticulate, i. 194.
— size of, i. 43.
— special absorptive, for salt solutions, i. 85.
— suction, in grasses, &c., i. 115.
— transpiring, nature, situation and arrange-
ment, i. 278.
Cell-sap, acidity, i. 511.
—— acid reaction, i. 463.
—— chief contents, i. 41.
— — where secreted, i. 33.
Cell-tissues, sorts of, i. 586.
Cellulares, of De Candolle, ii. 603.
Cellulose, i. 216, 263, 458.
— changes undergone in walls of epidermal
cells, i. 309.
— iu starch, i. 460.
— occurrence and function, i. 573.
— percentage composition, i. 454,
— transformation, i. 601.
Cell-union, modes of, i. 585.
Cell-wall, adaptability, i. 573.
—-—and absorption of carbon dioxide, i.
368.
— — canals in, i. 45.
—— composition, &ec., i. 42, 43,
—— demolition of, i. 47.
—— part played in ascent of sap, i. 270.
— — passages for food-absorption, i. 57.
— ~— polarization, i. 568.
— — protoplasm in, i. 581.
— — stratification, i. 44.
— — striation and structure, i. 569.
—— structure and growth, i. 511.
—— structure in relation to absorption of
food-salts, i. 72.
Cell-walls, in three dimensions of space, i.
57.

—— in two dimensions of space, i. 577.

Celtis australis, food of Libythea Celtis, ii.
488.

Celtis occidentalis, asymmetrical leaves,

i. 420.
—— bud-scales, i. 626.
— — reserve-buds, i. 32.
Cement, of tendril adhesive discs, i. 699,
Centaurea, autogamy, ii. 361.
— decurrent leaves, ii. 336,
— hybrids, ii. 585.
— mcvements of stamens, ii. 252,
— protection of pollen, ii. 126.
Centaurea alpestris and bud-galls of Diastro-
phus Scabiose, ii. 543.
Centaurea alpina, protection by ants, ii.

Centaurea Badensis, and bud-galls of Dia-
strophus Scabiose, ii. 543,

Centaurea Balsamita, capitate hairs, i. 229.

—— Persian steppes, varnish-like covering,

i. 230, 313.

— — secretion, i. 237.

—— varnish coating of capitate cells, i. 230.

Centaurea Cyanus, effect of dry soil, ii, 500.

— — inflorescence, ii. 184.

— — light and growth, ii. 508.

— — movements of stamens, ii. 252.

— — peripheral flowers, ii. 187.

— — scentless, ii. 209.

Centaurea Grafiana, See Centaurea sordida.

INDEX,

Centaurea Jacea, pollen-grain, ii. 100,

Centaurca montana, florets and autogamy,
ii. 360.

Centaurea napuligera, roots, i. 760.

oe Pseudophrygea, catapult-fruits,
ii. 841.

— — stomatal protective hairs, i. 292,

Centaurea Ragusina, hairs, i. 321.

Centaurea rupestris and C. Scabiosa, hybrid
of, ii. 562.

aa Ruthenica, protection by ants, ii.

Centaurea Scabiosa and bud-galls of Dia-
strophus Scabiosw, ii. 543.

Centaurea sordida, hybrid, ii. 563,

Centaury. See Erythrea.

Centipede, in utricle of Sarracenia purpurea,
i. 126.

Centipedes, protection against, ii. 445,

Central cylinder of root, i. 762.

Centranthus, pollen deposition, ii. 277.

Centranthus ruber, change of position of
anthers and stigmas, ii. 305.

— — flower, ii. 240.)

—— honey protection, ii. 241.

— — inflorescence and flowers, ii. 305.

Centrifugal inflorescence, i. 377.

Centripetal inflorescence, i. 737.

Centrolobium robustum, fruit protection, ii.
443, 445.

Centrosperme, bracts of, achlamydeous, ii.

— families of, ii. 748.
Centunculus, opening of flower, ii. 212.
Centunculus minimus, alluring floral tissue,
ii. 170.
— — autogamy, ii. 332.
— — duration of flowering, ii. 213.
—— stem, i. 656.
— — weather and autogamy, ii. 391.
Century Plant. See Agave Americana.
Cephalanthera, ii. 737.
— habitat and foliage, i. 110.
Cephalaria, pollen deposition, ii. 278.
Cephalaria alpina, stigma, ii. 381, 283,
Cephalonion-galls, ii. 532.
Cephalotaxus, protection of pollen, ii. 124,
Cephalotus, i. 134, 638,
Cephalotus follicularis, leaves heteromorphic,
shape of traps, &c., i. 131.
Ceramium, where thrives best, i. 105.
Cerasin, cherry-gum, i. 458.
Cerastium arvense, autogamy, ii. 355.
Cerastium chlorefolium, protection of
pollen, ii. 120.
tium lanat: t y, ii. 355,
Cerastium longirostre, autogamy, ii. 338.
Cerastium macrocarpum, capsule in dry and
wet weather, ii. 448.
—— mites and flower metamorphosis, ii.
548.
Cerastium triviale, gall-mites and flower
metamorphosis, ii. 548.
Ceratium, ii. 625.
Ceratocephalus falcatus, hooked fruit, ii.

Ceratodactylis, protection of sporangia, ii. 13.

Ceratonia Siliqua, ii. 552.

— — fruit, ii. 535.

Ceratonion, term applied to horn-like gall, ii.
532.

Ceratophyllum, as lime accumulators, i. 260.

— embryo, ii. 450.

— food-absorption, i. 765.

— sub-aqueous, no roots, i. 76.

Ceratopogon, in Aristolochia Clematitis
flower, ii. 226.

— in inflorescence of Arum, ii. 164.

Ceratopteris, protection of sporangia, ii, 13.

Ceratopteris thalictroides, frond-buds, ii. 39,

Ceratozamia, Central America, ii, 720.

— cotyledon in germination, i. 606.

Cercis siliquastrum, anthocyanin in buds, i.

484.

—— leaf-blades, i. 408.
— — reserve-buds, ii. 32.
— — torsion of leaf-stalks, i. 418.

937

Cercis siliquastrum, venation, i. 632.
Cereals, positions of leaf-blades, i. 428.

— reared in artificial culture solution, i. 100.
Cereus, i. 327.

— and night visitors, ii. 196, 197.

— autogamy, ii. 347.

— climbing roots, i. 754.

— course of pollen-tubes, ii. 410.

— on trees, i. 106,

— spines, i. 446.

Cereus dasyacanthus, autogamy, ii. 347.

— — whole plant, ii. 787.

Cereus giganteus, flower and fruit, ii. 787.
Cereus grandifiorus, opening and closing, ii.

—— ovary, ii. 77.

—— ovules, ii. '77.

— — size of flowers, ii. 185.

Cereus nycticalus, Pl. VII., arrangement of

perianth-leaves, i. 641.

— — climbing roots, i. 702.

— — opening and closing, ii. 212.

—— size of flowers, ii, 185.

Cerinthe, autogamy, ii. 379.

— pollen sprinkling, ii. 275,

Ceroxylon andicola, height, i. 712; ii. 740.

—— vertical range, ii. 742.

Cesalpino, Italian botanist; views on struc-
tural variation, i. 8.

— system of classification, ii. 601.

Cestrum, protection of pollen, ii. 118.

Cestrum i corolla and aut >
ii, 367.

Ceterach, hybrids in, ii. 582.

Ceterach officinarum, rolling up of frond, i.
314. -

Cetonia, abode in flowers, ii. 163.

— and aminoid scents, ii. 207.

Cetraria islandica, fruticose lichen, Pl. XV.,

ii. 694.

—— pyenidia, ii. 693.

Cheerophyllum, geitonogamy, ii. 320, 324,

— how protected, i. 451.

Chzrophyllum aromaticum, flowers, sorts of,
ii, 296,

Cherophyllum bulbosum, germination, i. 622.

Cherophyllum Cicutaria, anthocyanin, i. 522,

— — flowers, sorts of, ii. 296.

Cherophyllum hirsutum, behaviour of sta-
mens, i. 740.

Cheetocladium, sporangioles, ii. 673,

Cheetopeltis, thallus, ii. 653.

Cheetophora, reticular, i. 586.

— thallus, ii. 652.

Cheetophoracez, characteristics, ii. 652.

Chaffweed. See Centunculus minimus.

Chalazogame, of Treub, ii. 616.

Chalazogamic fertilization in Alnus, ii. 413.

—— in Amentacew, ii. 614.

—— in Carpinus, ii. 412.

-— — in Casuarina, ii. 616.

Chalcididz and Ficus, ii. 160.

Chamecyparis, winter colour, i. 485.

Chameedorea, cotyledon in germination, i. 606,

Chameorchis alpina, allurement of insects,
ii, 206.

Chameerops excelsa, fruits, ii. 740.

Chamerops humilis, geographical distribu-
tion, ii. 740.

-— height, i. 712.

Chamomile, Wild. See Matricaria chamo-
milla.

Change of position of anthers and stigmas,
ii. 305.

Chantarelles. See Cantharellus cibarius.

Chantransia, epiphytic, i. 161.

Chara, a genus of stoneworts, i. 260.

— embryology, ii. 61.

— lime incrustation, ii. 660,

— structure, i. 590.

Chara ceratophylla, lime accumulator, i. 260,

Chara crinita, asexual fruit-formation, ii. 467.

— — parthenogenesis, ii. 464.

Chara foetida, ii. 660.

—— ash constituents, i. 68.

Chara fragilis, ii. 63.

— — life-history, ii. 659,

938

Chara fragilis, structure and reproduction,
ii. 660.

Chara rudis, great lime accumulator, i. 260.

Chara stelligera, starch stars, ii. 660.

Characee, i. 424; ii. 606.

—apical-cell, division, i. 578.

— fossil, fruits, ii. 661.

— lime deposition, strengthening, i. 425

— structure and reproduction, ii. 659.

Characium, nature of, ii. 639.

Charales, ii. 659.

Cheilanthus odora, rolling up of frond, i. 314.

Cheiranthus Cheiri, possible cause of doub-
ling, ii. 554.

—— scent, ii. 201.

—— vitality of spermatoplasm, ii. 96.

Chelidonium, autogamy, ii. 341.

— ovary, ii. 76,

Chelidonium majus, caruncle, ii. 425.

——epiphyllous buds, ii. 43.

—— latex, i. 470.

Chemical affinity, i. 58.

Chenopodiacez, ii. 468.

— andreecium, ii. 750.

— embryo, ii. 422.

— exstipulate, ii. 749.

Chenopodium Bonus-Henricus, i. 450. _

Chenopodium Quinoa, endosperm, ii. 750.

Cherleria sedoides, nectaries, ii. 176.

Chermes, parthenogenesis, ii. 464.

INDEX.

Chlorophyll, modus operandi, i. 379.
— presence in all members, i. 375.
— properties, composition, ash,
about, i. 372.
— protection, i. 390.
Chlorophyll-corpuscles, action on carbonic
acid, i. 60.
— — and decomposition of carbonic acid, &c.,
i. 63, 465, 371.
— — and streaming protoplasm, i. 34.
—— arrangement, i. 375.
—— changes in autumn leaves, i. 486.
— — composition and activity, i. 430.
— — function, general considerations, i. 377.
——§in motile protoplasts, i. 30.
——in protonema of Luminous Moss, i, 385.
—— movements, i. 380.
—— of Floridew, i. 390.
— — protean properties, i. 381.
——shape, &c., i. 42, Pl. I.
—— situation in cell, shape,
number, i. 371, 373.
— —starch-grains in, i, 459.
Chlorophytum comosum, vegetative propa-
gation, ii. 820.
Cholera, i. 162, 163, 265, 506.
Cholera Bacterium. See Spirochete choleree
asiatice.
Chondrilla, geitonogamy, ii. 319.
Chondrioderma difforme, life-history, i. 572.

theories

multiplication,

Chermes abietis, and gall for
544, 551.

Cherry, Dwarf. See Prunus Chamecerasus.

— protection, ii. 446.

Cherry-gum, source, i. 458.

Chervil. See Cherophyllum.

Chestnut. See Castanea.

Chickweed, common. See Stellaria media.

Chili Pine. See Araucaria imbricata.

Chinese, and artificial crossing, ii. 555.

— galls, ii. 535.

— Primrose. See Primula sinensis.

—Tree of Heaven. See Ailanthus glandu-
losa.

Chirita sinensis, epiphyllous buds, ii. 43.

ii. 534,

Christi: time of flowering, i. 518.

Chromatophore, behaviour in Mougeotiacez,
ii, 658.

— fate in male gamete of Spirogyra, ii. 658.

— of Chlamydomonas, ii. 629.

— of Hydrodictyon, ii. 640.

— of Pediastrum, ii. 639.

— reduction in male gametes, ii. 633.

Chromatophores of Conjugate, ii. 654.

— of Desmids, ii. 655.

— of Dinoflagellata, ii. 625.

— of Spirogyra, ii. 654.

Chroococcacez, as lichen-alga, ii. 692.

— characteristic genera, ii, 621.

Chroococcus, alga of Cora, ii. 695.

Chironomus and Aristolochia Cl ii,

Chroocc brick-red patck

244,

—and Arum Italicum, ii. 165.

Chitinous insects, protection against, ii. 237.

Chives. See Allium Schenoprasum.

Chlamydomonadez, description, ii. 628.

Chlamydomonas, reproduction, ii. 629.

— vacuoles of swarm-spore, i. 30.

Chlamydospore and teleutospore, ii. 684,

Chlamydospores, in Hemiasci, ii. 674.

— nature of, ii. 685.

— of Ascomycetes, ii. 676.

— of Hemibasidii, ii. 674.

— of Mucor, ii. 673,

Chlorangium, life-cycle, ii. 636,

Chloranthy. See Antholysis.

Chlorenchyma, of switch-plants, i. 331.

— transpiring tissue, i. 278.

Chlorine, i. 83.

— in ash of plants, i. 66.

Chlorochytrium Lemnz, habitat, life-history,
ii. 637.

Chlorophyces, ii. 606.

— alliances of, ii. 620.

— biological importance, ii. 627.

— description, ii. 627.

— reproduction, ii. 628.

Chlorophyll, i. 460.

— absence not essential character of sapro-
phytes, i. 103.

—and depth of water, i. 387.

— and light, i. 391; ii. 510.

— distribution in mesophyll, i. 279.

— fluorescence and function, i. 519.

— in aérial roots, i. 754.

— in Alga, i. 375.

— in cotyledons, i, 622.

— in cotyledons and endosperm of Mistlet

i. 105.

Chroolepidez, symbionts of Lichens, dis-
persal, i. 246.

Chrysanthemum and ancient crossing, i. 555.

Chrysanthemum Leucanthemum, effect of
mutilation, ii. 517.

Chrysobalanus, flower, ii. 293, 779.

Chrysosplenium, dehiscence of pollen-sacs,
ii, 92,

Chrysosplenium alternifolium, autogamy, ii.

Chytridez, microscopic parasites, i. 169.

— selection of host, i. 171.

Chytridiaceze, ii. 606, 668.

— characters, ii. 671.

— sporangia and spores, ii. 17.

Chytridium Olla, life-history, i. 170.

—— sporangia, &c., ii. 17.

— — swarm-spore development, ii. 669.

Ciboti protection of ia, ii. 13.

Cicada and cuckoo-spit, ii. 490, 544.

Cichorium, protection of pollen, ii. 114.

Cichorium Intybus, latitude and closing, ii.
217, 218.

Cicuta virosa, absorptive cells of, i. 91.

Cider, i. 507.

Cilia, fate of, i. 31.

— of Bacteria, ii. 623.

— of swarm-spores, ii. 17.

— of Vaucheria clavata, i. 24.

— sorts of, i, 29.

— vibratile, function of, i. 57.

Cilissa, sheltering in flowers, ii. 163.

Cimicifuga, coloured stamen-filaments,ii. 183.

— nectaries, ii. 179.

Cimicifuga foetida, scent, ii, 202.

Cinch le, ii. 431.

i. 206.
—inrelation to saprophytism, i. 102.
— in roots, i. 766.
— iron necessary for formation of, i. 67.

— seed, ii, 423.

Cincinnus, i. 738.

Cinclidotus riparius, as mud-collector, i.
267.

Cinnamomum, dehiscence of pollen-sacs, ii. 93.

— fossil, i. 636.

— protection of pollen, ii. 124.

— venation, i. 629.

Cinnamomum Zeylanicum, ii. 752.

Cinnamyl-alcohol, scent, ii. 200.

Cinnyride, and transference of pollen, ii. 247.

Cinquefoil. See Potentilla.

— Marsh. See Comarum palustre.

Cinquefoils, vernation, i. 350.

Cirexa, pollen-graing, ii. 99, 101, 102.

Circeea alpina, absorptive cells and food-

absorption, i. 114.

—— autogamy, ii. 343, 344.

— — flower, ii. 236.

— — fruit, ii. 343.

— — habitat, i. 110.

—— inflorescence and flowers, ii. 343.

—— pollen-grains, ii. 98.

—— tubers, ii. 796.

Circzea Lutetiana, hooked fruit, ii. 871.

Circumnutation, nature of, i. 684.

Cirrhus foliaris, &c., i. 692, 694.

Cirsium, distribution of sexes, ii. 299.

— hybrids, ii. 558, 585.

— imperfect flowers, ii. 294.

— results of various crossings, ii. 560.

— spinose leaves, i. 438.

— variation in hybrids, ii. 593.

Cirsium affine, vegetative propagation, ii.
459.

Cirsium aquilonare, hybrid, ii. 560.

Cirsium arvense, and bud-galls of Urophora

cardui, ii. 543.

— — and Puccinia suaveolens, ii. 525.

—— &c., scent, ii. 202.

—— shade and growth, ii. 506.

Cirsium Erisithales and C. palustre, hybrids,
ii. 559.

Cirsium heterophyllum and C. canum, two-
coloured leaves, habitat, i. 293.
——and C. oleraceum, hybrid between, ii.

459.
——and C. spinosissimum, hybrid from, ii.
459.

Cirsium Linkianum, ii. 560.

Cirsium nemorale, i. 436.

— — deciduous plumes, ii. 860.

—— pollen-grains, ii. 99.

Cirsium ochroleucuw, hybrid, ii. 560.

Cirsium oleraceum and OC. heterophyllum,
hybrids, ii. 559.

Cirsium Pannonicum and C. Erisithales, hy-
brids, ii. 559. :

Cirsium purpureum, vegetative propagation,
ii. 458.

Cirsium spinosissimum, i. 450,

—— coloured bracts, ii. 183.

Cirsium tataricum, hybrid of C. canum x C.
oleraceum, ii. 586.

Cissus, anthocyanin, i. 484.

— host of Rafflesias, i. 200.

— tendrils, i. 694, 697, 699.

— plants, used as vegetable springs, i. 271.

Cissus Veitchii. See Vitis inconstans.

Cistus, zstivation, ii. 210.

— conducting tissue for pollen-tubes, ii. 410.

— duration of flowers, ii. 214.

— hairs, i. 323,

— hybrids, ii. 584.

— nectarless, ii. 167.

— protection of pollen, ii. 124.

— shrubs, hosts of Cytinus Hypocistus, i.
204.

— sticky forms, ii. 235.

Cistus Clusii, &c., varnish-like coating, i. 312.

Cistus Creticus, opening and closing, ii, 212.

Cistus laurifolius, varnish-like coating, i. 312.

Citric acid, i. 463.

— — in Nepenthes pitcher, i. 135.

Citron, oil of, ii. 203.

—of Florence. See Citrus medica.

— scent, ii. 203.

‘Citrus, buds on leaf-cuttings, ii. 43.

-- hybrids, ii. 569.

— receptacle, i. 746.

| Citrus medica, ii. 569.

ai asa bordered pits compared to, i
277,

Cladode, i. 332, 333, 353.

— prickly, i. 434.

Cladonia, fruticose lichen, ii, 694,

Cladonia coccifera, ii. 694.

eee furcata and Protococcus, i. 245,

Cladonia macilenta, Pl. X'V., ii. 694.
Cladonia pyxidata, Pl. XV., ii. 694,
Cladonia rangiferina, Pl. XV,, ii. 694,
Cladophora, continual cell-division, i. 581.
— life-history, ii. 651.

— reticular, i. 586.

— wide distribution, ii. 651.

ae ees characteristic features, ii.

Cladrastis lutea, scent, ii. 201.
Clamp-cells, of Orchid roots, i. 220.
Clandestina, nectary, ii. 174.
_ z pollen sprinkling, ii. 272.
destina rectiflora, geitc y, ii, 331.
en viscin of pollen-grains, ii. 101.
Clarkia pulchella, abortive st li. 294.
Clary, Wild, Salvia Verbenaca, section of
petiole, i. 22.
Classification and evol
— basis of, i. 6.
— early methods, ii. 600.
— of De Jussieu (1789) and De Candolle (1813),
1.15; ii. 602, 603.
— of galls, ii. 528.
— of plants, basis of Linnean System, ii. 86.
— outline of, ii. 617.
— principles of, i. 15.
Clathrocystis, habitat, fi. 621.
Clathrus, gleba, ii. 691.
Clathrus cancellatus, ii. 690.
Clatroptychium, i. 573.
Clavaria, spore- formation, ii. 20.
— structure, i. 589,
Clavaria aurea, i. 112; ii, 21, 685, 688.
Clavaria inzequalis, ii. 688.
Clavarie, hymenium, ii. 688.
Claviceps, ii. 680.
—asci and ascospores, ii. 19, 680.
— spore-dispersal, ii. 827.
Claviceps purpurea, ii. 680.
— — localized attack, i. 168.
— — spore-dispersal, i. 461.
Claw, of petal, ii. 87.
Clay, i. 83.
Claytonia perfoliata, autogamy, ii. 365
Cleavage planes and striz, i. 568.
Cleistogamous flowers and habitat, ii. 394,
—— characteristics, ii. 392.
Cleistogamy, nature of, ii. 391.
Clematis, forced shoot, i. 564.
— liane-like, i. 670.
— protogynous, ii. 311.
— tendrils, i. 692, 694.
Clematis Flammula, plumed achenes, ii. 858.
— — pocket-galls on, ii. 532.
Clematis integrifolia, autogamy, ii. 349.
—— protection of pollen, ii. 118.
Clematis recta, pocket-galls on, ii. 532.
Clematis Vitalba, less, ii, 167.
—— protogynous, ii. 310.
—— scent, ii. 200.
Cleome ornithopodiodes,
minor degree, i. 156.
— — sticky foliage, ii. 236.
Clerodendron fistulosum, myrmecophilous,
ii. 233.
. Clerodendron sanguineum, colour-contrast
in flower, ii. 191.
Clianthus Dampieri, Australian, leaf, diur-
nal positions, i. 534,
— — colour-contrast in flower, ii. 190.
Clianthus puniceus, propagation by leaf-
cuttings, ii. 41.
Climate and distribution, ii. 1, 879.
— and opening and closing of anthers, ii. 124.
— and protection of pollen from wet, ii. 106.
— effect on fall of leaf, i. 355.
— in relation to hairiness, i. 319.
— negative in origin of species, ii. 594.

on of plants, ii. 607.

carnivorous in

INDEX.

a conditions and flower-production,

ii, 474,

— — great variability of, correlation of plant

structure to, i, 284.

Climatology and plant development, i. 564.

Climbers, perennial, mechanical tissue, i. 733.

Climbing aroids, ii. 744.

Climbing hooks of Hop, i. 688.

Climbing Palm. See Desmoncus.

Climbing Palms, ii. 741.

— — height, &c., ii. 740.

Climbing plants and lateral pressure, i. 475.

—-— formerly held to be parasites, i, 159.

—— leaf arrangement, i. 420,

Climbing stem, application of term, i. 671.

— — characteristics, i. 700.

Climbing stems, transitional condition, i. 708.

Clinging fruits, ii. 867.

Clinging roots, mechanical adaptation, i. 762.

Clinopodium vulgare, distribution of sexes,
ii. 300.

Clip-mechanism, of Asclepiad pollinia, fi.
258.

Clivia, ii. 734.
sake nobilis, vitality of spermatoplasm, ii.
6.

Clock, floral, of Linnzeus, ii. 215.

Closterium, Pl. L., ii. 55.

— movement, ii. 654,

— swarming granules in, Pl. I., i. 35.

Closterium Lunula, i. 35; ii. 492, 655.

Cloudberry. See Rubus Chamemorus.

Clover. See Trifolium.

Clover-Dodder. See Cuscuta Trifolii.

Cloves, oil of, ii. 200.

— origin of, ii. 782,

Clove-scent, ii. 201.

Club-moss, Alpine.
pinum.

Club-mosses, description, ii. 713.

Club-tops. See Clavaric.

Clusia alba, lattice formation, i. 680.

— — root-hairs and earth particles, i. 87.

Clusia rosea, recently considered a vampire,
i. 159,

Clusiacez, lattice formation, i. 678, 681.

— roots, i. 756, 761.

Clusius, a Belgian, first travelling botanist,
i. 5.

— Historie Plantarum, ii. 1.

— system of classification, ii. 601.

Cluster-gall, ii. 542, 545.

Clypeola Messanensis, autogamy, ii. 339.

Coat, of ovule, i. 644.

Cobzea, pollen deposition, ii. 278.

Cobzea scandens, autogamy, ii. 384.

— — cross-fertilization, ii. 304.

— — flower, ii. 240.

— — flower and autogamy, ii. 385.

—— pollen-grains, ii. $8, 100, 102, 127.

— — tendril, i. 697.

Cobalt, in dust, i. 81.

Cocain, i. 462.

Coccocarpia molybdea, ii. 693.

— — structure, i. 245.

Coccoloba platyclada, Solomon Islands, i. 334.

Cocconema Cistula, ii. 626.

Cochlearia Armoracia, heterogamy advan-
tageous, ii. 578.

Cochlearia fenestralis, Siberia, cold resist-
ance, i. 543.

Cochlearia Greenlandica, autogamy, ii. 339.

Cochlearia officinalis, cold resistance, i. 543.

Cock’s-foot Grass. See Dactylis.

Cock's-tail Alga. See Spirophyton.

Cocoa-nut, Double, ii. 740.

Cocoa-nut Palm. See Cocos nucifera.

Cocos nucifera, dimensions, i. 712; ii. 451.

Codiacex, characteristics of thallus in, ii. 645.

Codium, colonies, i. 585.

Codium tomentosum, British, ii. 646.

Coelanthe, autogamy in, ii. 372.

Coelebogyneilicifolia, parthenogenesis, ii. 466.

Ccelenterates and Pleurococcacee, ii. 637.

Cceloblasteze, ii. 606.

Coeloglossum and Orchis, hybridization, ii.
583.

See Lycopodium al-

939

Ocelogyne plantaginea, ovarian hairs, ii. 81.

—— ovary, ii. 83.

Coenobe, of Volvox, ii. 635,

Coffea, embryo, cotyledons, i. 600.

Cohesion, i. 58,

Cohn, classification of Thallophytes, ii. 606.

Cohort, of Braun, ii. 605,

— subdivision of class, ii. 617.

Colchicacex, characteristics, ii. 730.

Colchicum, autogamy, ii. 372.

— extrorse anthers, ii. 95.

— opening and closing, ii. 220.

— protection of pollen from rain, ii, 112.

— protogynous, ii. 311.

— styles, i. 645.

Colchicum autumnale, ii. 729.

— — autogamy and heterostylism, ii. 374.

—— depth of corms, i. 552.

— — flower-opening constant, i. 559.

— — nectaries, ii. 175.

—— odourless, i. 431.

— — opening of flowers and growth, ii. 220.

—— pollen-grains, ii. 99.

—— starch, i. 459.

Cold, effect on various plants, i. 543.

Coleochete, cilia of, i. 29.

— life-history, ii. 653,

— relationship to Florides, ii. €54.

Coleochzeteze, ii. 606.

— as Lichen-alga, ii. 693.

Coleosporium senecionis, hetercecism, ii. 686.

Coleus, and cold, i. 545.

Collective and aggregate fruits, ii. 437.

Collective fruit, ii. 436, 438.

Collema, distribution of alga in, ii. 694.

Collema pulposum, ii. 694.

—— a gelatinous Lichen, surface view and
section, i. 244.

Collemacez, nutrition, i. 81.

Collenchyma, in perennial twining stems, i.

733.
— nature and properties, i. 231, 726.
Colletia, leaves and phylloclades, i. 334, 335.
434,

Collinsonia Canadensis, autogamy, ii. 350.

Collomia, seed-cement, i. 615.

— seed-dispersal, ii. 838.

Colocasia, arrangement of foliage-leaves, i.
3.

Colocasia antiquorum, inflorescence, &c., ii.
742.

Colonies of plants, isolated, examples, i. 528.

Colony, application of term, i. 585.

Colour and elevation, ii. 511.

— of hybrids, ii. 566.

— of water, i. 388.

Colour-contrast in flowers, ii. 184, 189, 190,
191, 193.

Coloured fruits and seeds, ii. 865.

Columella, in Anthocerotacez, ii. 698.

— of Moss-capsule, ii. 702.

— of Splachnun, ii. 703.

Column, marble, near Castle of Ambras,
Lichens on, i. 247.

Column of Epipogium aphyllum, ii. 226.

— of Orchid as insect platform, ii. 225.

— of Orchid ovary, ii. 253.

— of Phalenopsis Schilleriana, ii. 227.

Columniferz, of Braun, ii. 605.

Colutea arborescens, isolated colonies, i.
528.

Comarum palustre, colour of sepals, ii. 183,

— — creeping stem, i. 662.

Combined girders, of stems, i. 728.

Comfrey. See Symphytum,

Comma-bacillus, of cholera, i. 163.

Commelyna ceelestis, autogamy, ii. 357.

Commelynacex, calcium oxalate crystals, i.

— cotyledon in germination, i. 606.
Compass plants, i. 337.

Complexity and higher development, ii. 598,
Composite, ii. 599, 765.

— absorbent leaf-teeth, i. 238.

— estivation in, ii. 210.

— as insect shelters, ii. 163.

— autogamy in, ii. 359, 363, 372.

940

Composite, calyx and fruit, ii. 434.

— catapult-mechanism, ii. 840.

— coloured bracts, ii. 183,

— decurrent leaves, i. 336.

— dichogamy and hybridization, ii. 316.

— division of sexes in capitulum, ii. 296.

— extrusion of pollen, ii. 359.

— flowers after pollination, ii. 286.

— flowers and radiation, i. 530.

— geitonogamy in, ii. 318,

— honey-protection, ii. 238.

— hybrids, ii. 585.

— insect guests, ii. 230, 245.

— integument of ovule, ii. 81.

— laticiferous tubes, i. 470.

— massing of flowers, ii. 186.

— number of species, ii. 318.

— offshoot formation in, ii. 453,

—of Mediterranean district, most remark-
able for hairy species, i. 317.

— ovary, ii. 78.

— pericarp mucilage, i. 615.

— “Phrygian”, i. 444.

— pollen, ii. 85, 99.

— pollen deposition in, ii. 278.

— position and kinds of leaves, i. 409.

— protandrous, ii. 312.

— — dichogamy in, ii. 311,

— protection against herbivorous beetles, ii.
233.

— protection of pollen, ii, 114, 120.

— radical buds, ii. 28.

— storage of pollen, ii. 94.

— stylar papille, ii. 285.

— sweeping hairs, ii. 615.

— use of involucral leaves in classification,
ii, 562.

— vertical leaves, i. 337.

— water receptacles, i. 156.

Compound leaves, movements of leaflets, ii.

— radicles, chemical, i. 454.

Concealment of honey, ii. 180, 181.

Conceptacles, of Fucus, ii. 663, 664.

Conducting apparatus, mutual relations of
two kinds, i. 473.

— cells of leaves, i. 472.

— organs, junction, i. 471.

— tissue, soft, necessity for protection, i, 478.

— tissues, division of labour, i. 479.

—— strengthening of, i. 474.

Conduction, of water, i. 366,

Cone, female, of Abietinez, ii. 721,

— fertile, of Lycopodium, ii. 476.

— of Conifers, ii. 440.

— of Cycads, ii. 718.

— of Equisetum arvense, ii. 476, '712

— of Juniperus, ii. 442.

Conferva, bleaching by sun, i. 391.

Confervoidee, as Lichen-alge, ii. 692

— description, ii. 648.

— reticular, i. 586.

Conglutin, of Almonds, i. 458

Conical receptacle, i. 746.

Conidia of Agaricus, ii. 684.

— of Amanita phalloides, ii. 685.

— of Claviceps, ii. 680.

— of Empusa Musca, ii. 672.

— of Entomophthora, ii. 672.

— of Hemibasidii, ii. 675.

— of Lichens, germination, ii. 693.

— of Peronospora viticola, ii. 670.

Conidial hypha, of Eurotium, ii. 679.

Conidium, from teleutospore basidium, ii.
684,

— of Eurotium, ii. 679.

Conifere, ii. 437, 719, 720.

— absorption-cells, i. 86.

— amount of pollen, ii. 151,

— anemophilous, ii. 133.

— contractile layer of anther, ii. 94.

— distribution of stomata on leaves, i. 281,

— dwarf, artificially produced, ii. 518,

— Endlicher’s grouping, ii. 604,

— evergreen, absorptive cells, i. 91.

— form of chlorophyll-containing cells, 1. 374.

— fruits and seeds, ii, 442, 443.

INDEX,

Conifers, hybrids among, ii. 582.

— inflorescences, position, ii. 136.

— long and short branches, i. 659; ii. 471.

— mycorhiza in, i. 251.

— Paleozoic, ii. 612.

— phyllotaxis, of shoots and cones, i. 402.

— pollen-grain, ii. 96.

— protection of pollen, ii. 117.

— scale-leaves and light, i. 412.

— secondary thickening, ii. 720.

— wax on under leaf-surface, i. 292.

Conium maculatum, odour, i. 431; ii. 199.

Conjugatie, ii. 606, 620, 654.

— fertilization, ii. 54.

Conjugation, chemical influence in, ii. 658.

— nature of, ii. 54.

— of Diatoms, ii. 626.

— of gametes, in Chlorophyces, ii. 630.

Conj i 1, of Desmids, ii. 654,

— of Spirogyra, ii. 647.

Connate, of leaves, i. 596.

— anthers, of Composite, ii, 115,

Connective, of anther, ii. 89.

Conocephalacez, ii. 758.

Conopodium, i. 746.

Continuity, liquid, between absorptive cells
and earth film, i. 85.

Contractile cells of anthers, ii. 93,

Contrivances, floral, correlation to insect
visits, ii. 256.

— for loading insects with pollen, ii. 246,
247, 249.

— for retention of rain-water, i. 156.

— for the exhalation of water-vapour, i. 226.

Convallaria, forcing, i. 564.

— protection of pollen, ii. 118.

Convallaria majalis, flower, ii. 729.

— flower-opening constant, i. 559.

— leaves and rain conduction, i. 94.

— protection of pollen, ii. 119.

— scent, ii. 200, 201.

— sheltering of pollen, ii. 109.

Convallaria polygonatum, habit in relation
to habitat, i. 286.

— scaly stem, i. 652.

Convallariacex, characteristics, ii. 732.

Convolvulacez, ii. 771.

— estivation, ii. 210.

— autogamy in, ii. 333, 335,

— include parasitic Cuscute, i. 171.

— nectaries, ii. 175.

Convolvulus, dehiscence of pollen-sacs, ii. 93.

— extrorse anthers, ii. 95.

— guides to honey, ii. 249,

— hairiness, i. 317.

— inflorescence, i. 746.

— nutation, i. 683,

— pollen-grain, ii. 98, 100, 102,

Convolvulus arvensis, cotyledons, i. 621.

— — insect reception, ii, 230.

— — opening of flower, ii. 212.

——- scent, ii. 201.

Convolvulus 1
301.

Convolvulus sepium, cross-fertilization, ii.

301.

cross-fertilization, ii.

— — pollen-grains, ii. 98.

— — sinistrorse twining, i. 685.

Convolvulus Siculus, autogamy, ii, 333,

— — insect reception, ii. 230.

sia ot a sylvaticus, cross-fertilization,
ii. 301.

Convolvulus tenuissimus, &c., silkiness, i,
320, 321.

Convolvulus tricolor,

flower, ii. 190.

— — opening and closing, ii. 212.

Coprinus, fructifies in a night, i. 117.

Coprinus stercorarius, origin of fructifica-
tion, ii. 689.

Cora pavonia, ii. 692, 695,

all as marine lime-accumulators, i.

colour-contrast in

— lime deposition and resistance, i. 425,
Corallorhiza, i. 184; ii. 738,

— absorbent cells, i. 766.

— germination, i. 750,

Corallorhiza innata, description, i. 110-114.
—— scaly stem, i. 652.
Corchorus olitorius, bast-cells, i. 725.
Cordyceps, life-history, ii. 680.
Cordyceps militaris, parasite on caterpillars,
&e., i. 168.
Cordyceps Taylori, ii. 679.
Coriander. See Coriandrum sativum.
Coriandrum, geitonogamy, ii. 325.
Coriandrum sativum, germination constant,
i. 558.
— — offensive odour of roots, ii. 99.
Coriaria myrtifolia, twisting of internodes,
i. 417.
Cork, i. 469.
— buffer action, i. 474.
— nature of, i. 719.
— protective, i. 164; ii. 519.
Corky layer, of epidermis=cuticle, i. 309.
Cormophyta, of Braun, ii. 605.
— of Endlicher, ii. 604.
Cormus, subdivision, i. 655.
Corn, extrusion of water by young blades,
i. 271.
Cornacez, ii. 788.
— geitonogamy in, ii. 325.
Corn-cockle. See Agrostemma Githago.
Cornel. See Cornus mas.
Cornflower. See Centaurea Cyanus.
Corn-salad. See Valerianella.
Corn Sow-thistle. See Sonchus arvensis.
Cornus, honey, ii. 173.
— twisting of internodes, i. 417.
Cornus florida, coloured bracts, ii. 183.
— — &., geitonogamy, ii. 326.
— — inflorescence, ii. 184, 231.
Cornus mas, diameter, i. 722.
— — flower, tetrandria, ii. 289.
— — flowers, ii. 789.
— — hermaphrodite, ii. 296.
—— thermal constants, i. 559,
— — venation, i. 631.
Cornus sanguinea, i. 487.
— — scent, ii. 200.
Cornus Suecica, coloured bracts, ii. 183.
Corolla, accessory in fruit formation, ii. 433.
— and antogamy, ii. 365.
— application of term, i. 641.
— as insect platform, ii. 225.
— ringent, eestivation, ii. 211.
Corolliflorse, of De Candolle, ii. 603.
Corona-like ring, in Rafflesia Arnoldii, i. 203.
Coronia, insect reception, ii. 228.
Coronilla, pollen expulsion, ii. 260.
Coronilla varia, leaf positions, i. 533.
— — prostrate shoot, i. 664.
Corpusculum with pollinia, ii. 258.
Correa speciosa, hairs, i. 322, 324.
Corrigiola, prostrate shoot, i. 664.
Cortex, i. 468.
Cortex of root, functions, i. 762.
Corticium, texture and basidia, ii. 688.
Cortusa, protection of pollen, ii. 118.
— protogynous, ii. 311.
— unfolding leaves, i. 351,
Coryanthes, honey, ii. 172,
Corydalis, and humble-bees, ii. 239.
— germination, i. 622.
— honey concealment, ii. 180.
— one-sided raceme, ii. 224,
— petiole, i. 93.
— pollination, ii. 228.
— sheltering of pollen, ii. 110.
— staminal filament, ii. 88.
Corydalis acaulis, &., explosive distribution
of pollen, ii. 266.
Corydalis capnoides, stamen, ii. 87.
Corydalis cava, &c., behaviour to own and
foreign pollen, ii. 406.
— — flower-opening constant, i. 559.
—— &c., habitat, i. 654.
— — &c., leaf and light, i. 286.
—— protection of tubers, i. 551.
— — scent, ii, 202.
Corydalis fabacea, luxuriant growth on
Monte Baldo, i. 287.
— — scale-leaf, i, 625.

Corydalis lutea, flower, ii. 226.

—-— pollen-grains, ii. 98.

Corydalis ochroleuca, behaviour to own and
foreign pollen, ii, 406.

Corylacew, chalazogamio fertilization, ii. 412,

Corylus, cotyledons, i. 608,

— cupule, ii. 434.

— flowering, ii. 150.

— monoscious, ii. 297.

— phyllotaxis, i. 399,

— pollen, ii. 85, 151.

— pollen-storing and dispersion, ii. 94, 148.

— pollination, ii. 133.

— protection of pollen, ii. 119.

— venation, i. 631,

Corylus Avellana, flowers and fruit, ii. 147.

— — thermal constants, i. 559.

Corymb, i. 739.

Coryna, affinities, i. 193.

— description of, i. 193.

— geographical distribution, i. 193,

Coryne pistillaris, structure, i. 589.

Corypha umbraculifera, ii. 740.

—— inflorescence, i. 745.

— — of Ceylon, i. 287, 289.

Cosmarium polygonum, ii. 492, 655.

Cosmarium tetraophthalmum, ii. 492, 655.

Cosmic dust, i. 81.

Cotton Thistle. See Onopordon.

Cotton Tree. See Canavillesia tuberculata.

Cotton Tree, West Indian. See Hriodendron
caribeeum.

Cotyledon, i. 596, 608.

— habitat and cylindrical leaves, i. 327.

Cotyledon, meaning of, i. 15.

— of Onion, &c., i. 606.

— of Rhizophora, i. 602.

— of Sedges, &., i. 604.

Cotyledons, absent in Cuscuta, i. 172.

— absorbent cells, i. 600, 601.

—and nocturnal radiation, i. 530.

— chlorophyll in, i. 376, 622.

— general description, i. 598 et seq.

— liberation of, i. 610, 611.

— of Agrostemma Githago, &c., i. 610.

— of Angiosperms, ii. 421.

— of Trapa, &c., i. 609.

— of Welwitschia mirabilis, ii. 726,

— protection in germinating, i. 613.

— various, i. 599, 621.

Couch-grass. See Agropyrum repens.

Coumarin, scent, ii. 200.

Covering-galls, ii. 530.

— — nature of, i. 533.

Covering hairs, i. 322, 319.

Cow-berry. See Vaccinium Vitis-Idea.

Cow-parsnip. See Heracleum.

Cowslip. See Primula.

Cow-tree. See Galactodendron utile.

Cow-wheat. See Melampyrum.

Crabs, protective algal covering, i. 77.

Crack-willow. See Salix fragilis.

Crambe cordifolia, flowering, i. 745.

Crambe maritima, wound buds, ii. 29.

Crambe tataria, heterogamy ad 18,

INDEX,

Crategus Oxyacantha, spines, i. 443,

Craterantha, ii. 779,

Craterellus, ii. 688.

— resembles Padina, i. 112.

Craterellus clavatus, ii, 21, 685.

Craterium minutum, sporangia, ii. 618.

— — sporangial form, ii. 490.

Creation, considerations concerning, ii. 597.

Creepers, not parasites, i. 159.

— protection against lateral pressure, i. 475.

Creeping Avens. See Geum reptans.

Crenate, i. 233.

Crenothrix, ii. 622.

Crenothrix Kiihniana, storing of iron, ii. 624.

Crepis, autogamy, ii. 372, 374.

— geitonogamy, ii. 319.

Crepis grandiflora, as insect shelter, ii, 163.

— — autogamy, ii. 361.

Crepis paludosa, ligulate florets, ii. 236.

Cresses and animals, i. 432,

Cretaceous flora, i. 636.

Crete, Thistles, i. 438,

Crinum, ii. 734.

— buds on carpels, ii. 44.

— ovular tubers or buds, ii. 469,

Crithmum maritimum, i. 327.

Crocus, autogamy, ii. 332.

— corms, depth in soil and growth, ii. 407.

— protective rolling of leaves, i. 428.

— rolled leaves, i. 348.

— stomates, &c., i. 348,

Crocus albiflorus, autogamy, ii. 332.

Crocus multifidus, protection of pollen, ii.
112, 113.

Crocus sativus, duration of flowering, ii. 213.

— — stigma, ii. 279, 282.

Cronartium asclepiadeum, two hosts, ii. 615.

Crops, rotation of, i. 75.

Cross- and self-pollination, alternation of, ii.
335.

Cross-fertilization, aimed at, i. 739.

—— and inflorescence, i. 741.

— — between neighbouring flowers, i. 740.

——vchange of position of anthers and

stigmas, ii. 303.

—— in Equisetacer, ii. 68.

—— in Muscinew, ii. 65.

— — nature, ii. 300.

Crossing, and origin of species, ii. 599,

— artificial, antiquity, ii. 555.

— conditions of, ii. 404.

— juxtaposition of parental characters in, ii.
573

— perpetuation of results, ii. 555.

Crossogaster, and Ficus, ii. 162.

Cross-pollination, in crowded inflorescences,
ii. 318,

Croton, flowers, ii. 293.

Croton, gray-haired species, in Brazil, &c., i.
317.

Crowberry. See Empetrum.

Crow Garlic. See Allium vineale.
Crucianella, nectaries, ii. 177.

Crucianella latifolia, pollen-grains, ii. 98, 99.
Crucianella stylosa, flowers and transference

ii, 578.

Cranberry. See Vaccinium Crycoccus.

Craspedromous venation, i. 630.

Crassula, ii. 327. 2

Crassulaceze, annual, formation of offshoots,
ii, 452.

— heterostyly in, ii. 398.

— movements of stamens, ii. 250.

— nectaries, ii. 175.

— sticky foliage in, ii. 236.

Cratzegus, American species, i. 444.

— radical shoots, ii. 27.

— scent, ‘ii. 200.

— — trimethylamine, i. 462.

Crateegus coccinea, spines, i. 444.

Crateegus Crus galli, &c., spines, i. 444.

Crateegus monogyna, &c., and galls of Ceci-
domyia crateegi, ii. 546.

Crategus Oxyacantha, flower-opening con-

stant, i. 559.
—— possibility of transmitting gall-mite
effects by grafting, ii. 554,

of pollen, ii, 265, 267.
— — geitonogamy, ii. 331.
— — Persia, ii. 331.
— — protandrous, ii. 311.
Oruciferz, alkali-loving, i. 74.
— annual, no wild bybrids, ii. 584.
— anthocyanin, i. 520.
—autogamy in, ii. 335, 339, 348.
— bending of filaments and anthers, ii. 250.
— cleistogamy in, ii. 393.
— colour-contrasts in inflorescences, ii. 192.
— cuckoo-galls on, ii. 545,
— dehiscence of pollen-sacs, ii. 93,
— duration of blossom, ii. 214.
— epiphyllous buds, ii. 43.
— flowers after fertilization, ii. 286.
— fruit, ii. 432.
— fruit-protection in, ii. 442.
— gall-mites and flower metamorphosis in,
ii. 548.
— green cotyledons, i. 622.
— guides to honey, ii. 248.

941

Crucifers, hairs, T-shaped, &c., i. 321, 323.

— leaves, position and kinds, i. 409.

— nectaries, ii. 174.

— of Steppes, waxy bloom of leaves, i. 312.

— oriental, flowering, i. 745.

— ovary, ii. 75.

— perennial, hybrids, ii. 584.

— “Phrygian”, i. 444.

— phyllotaxis of inflorescence, i. 402.

— pollen, ii. 85, 100.

— pollen deposition in, ii. 278.

— protection of pollen, ii. 117, 121.

— protogynous, ii. 310, 312.

— scent of, ii. 202,

— substratum, ii. 498.

— tribes of, ii. 775.

Orupina vulgaris, creeping fruits, ii. 843, 844.

Crust, of earth, preponderant constituents,
i. 83.

i. 83.

Crustacea, as hosts for hydrophytes, i, 77.

— on Mangrove roots, i. 756.

— prey of Utricularie, i. 122.

Crustaceous Lichens, ii. 694.

Crusts, calcareous. See Lime.

Cryoconite, snow-dust, i. 38, 262.

Cryptocephalus violaceus, sheltering in Com-
posite, ii. 163,

Cryptogam, meaning of term, ii. 48.

Cryptogamia, i. 6.

— absence of blossom, ii. 72.

— fertilization, ii. 49, 67.

— fertilized under water, ii. 71.

— fruit-formation, ii. 49.

— hybrids among, ii. 583.

— new term for, ii. 9.

— new world revealed, i. 14.

— simplicity of sexual organs, ii. 70.

— spores of, ii. 9.

— Vascular, Paleozoic remains, ii. 612.

Cryptomeria, winter colour, i. 485.

Cryptomeria japonica, ii. 725.

Cryptus and Listera, ii. 256.

Crystal-forms of calcium carbonate, ii. 493.

Crystal growth, i. 568.

Crystalloids, of plants, i. 457.

Crystals, of plants, i. 457.

Ctenomyces serratus, habitat, i. 118.

Cuckoo-buds, ii. 544,

Cuckoo-flower. See Cardamine.

Cuckoo-gall, ii. 542, 544.

Cuckoo-pint. See Arwm maculatum.

Cuckoo-spit and Cicada, ii. 490, 544.

Cucubalus baccifer, weaving habit, i. 674.

Cucumis Melo, pollen-grains, ii. 97.

Cucurbita, i. 217.

Cucurbita maxima, fruit, ii. 452.

Cucurbita Pepo, cotyledons, i. 622.

— — germination, i. 611.

— — germination constant, i. 558.

— — pollen-grains, ii. 97, 98.

— — size of flower, ii. 186.

— — tendrils, i. 698.

Cucurbitacese, ii, 785.

— anthers, ii. 90.

— distribution of sexes, ii. 297.

— fruits, dimensions of, ii. 452.

— movements of cotyledons, i. 532.

— pollen-grains, ii. 97, 100.

Cudweed. See Filago.

Culm, i. 710, 714.

Cultural experiments, sources of error, i.
513.

Culture solution, i. 100.

Cultures, artificial, i. 66.

Cuphea, autogamy, ii. 345.

— liberation of cotyledons, i. 612.

— nectary, ii. 177.

— pollen-grains, ii. 99.

Cuphea eminens, autogamy, ii. 346.

Cuphea micropetala, flower, ii. 237.

— — flower structure and pollination, ii. 235.

— — protection of honey, ii. 235.

— — sticky bristles of calyx, ii. 237.

Cuphea platycentra, pollen-grain, ii. 100.

Cup-moss. See Cladonia pyxidata.

Cupressinez, arrangement of scales, ii. 440.

— cone characteristics, &c., ii. 725.

942

Cupressus, egg-cells, ii. 419.

— embryo development, ii. 438.

— fertilization, ii. 420.

— pollen-storing and dispersion, ii. 146.

Cupressus fastigiata, dimensions, &c., i. 720.

Cupressus sempervirens, female flower, ii.
443.

— ripe cone, ii. 443.

Cups, of Peziza, ii. 682.

Cupule, of Oak, ii. 435.

Cupuliferz, fertilization, ii. 413.

— mycorhiza, i. 251.

Curculigo, epiphyllous buds, ii. 44.

Curl disease of Peach, &c., cause of, ii. 524.

Currant-gall, on Oak, ii. 526.

Curvispina, section of Rhamnus, ii. 299,

Cuscuta, i. 182, 687.

— affinities i. 171.

— autogamy, ii. 344.

— distribution, i. 171.

— embryo, i. 596, 648, 750; ii. 450.

Cuscuta, European species annual, i. 175.

— life on host, i. 172, 174.

— scaly stem, i. 651.

— seed, i. 647.

Cuscuta Europea, weather and pollination,
ii. 391.

Cuscuta Trifolii, i. 172.

Cuticle, i. 62, 78, 278.

— and animals, i. 432.

— functions in leaves, i. 226, 284.

— general texture, modifications, i. 310.

— in relation to water-absorption, i. 227.

— modifications of, in rolled leaves, i. 302.

—of epidermal cells, impermeability to
water, ii. 309.

— of stoma, function, i. 164.

— on particular cells of hairs, i. 228,

Cuticularized layers, i. 309.

Cutleriacez, thallus, ii. 661.

Cutting, morphological value, ii. 6.

Cuttings, perpetuation of crossings by, ii.
555, 556.

— propagation by, i. 250, 251,

— root formation, i. 772.

Cyanogen, i. 454.

Cyanophyces, ii. 606, 621.

Cyathea, caudex, ii. 705.

Cyathea elegans, fertile pinna, ii. 711.

Cyatheacex, characteristics, ii. 706, 708.

Cyathus, structure, ii. 690.

Cyathus striatus, ii. 690.

Cycad, caudex, i. 714.

Cycadacew, description, ii. 718.

— fossil remains, ii. 636, 720.

— number of species, ii. 720.

Cycadales, ii. 718.

Cycad-cone, i. 193.

Cycads, at Kew, ii. 720.

— dimensions, ii. 718,

— diccious, ii. 299.

— mode of growth, i. 659.

— ovules, development of, ii. 81.

— pollen-grain, ii. 96.

— protection of pollen, ii. 124,

— seeds and carpels, ii. 441.

— spinose leaves, i. 438.

— vitality of spermatoplasm, ii. 96.

Cycas and Nostoc, ii. 622,

— ovule, ii. 418.

— ovule quite exposed, ii. 72.

Cycas circinalis, size of leaf, i. 287.

Cycas revoluta, carpel and ovules, ii. 74.

— — carpels, ii. 720.

— — group of, ii. 719.

— — integument of ovule, ii. 81.

— — seed-coat, ii. 439.

Cyclamen, autogamy, ii. 333, 379.

— cause of flecked appearance of leaves, i.
285.

— dehiscence of pollen-sacs, ii, 92,

— nectary concealment, ii. 181,

— pollen-sprinkling, ii. 274.

— ripening of fruit, ii. 873.

Cyclamen europeum, &c., anthocyanin, ii,

519, 520.
—— — duration of flowering, ii, 213,

INDEX.

Cyclamen europzeum, &c., scent, ii. 200, 201.

——stamen, ii. 91.

Cyclanthacex, dehiscence of pollen-sacs, ii.
92, 745.

Cyclanthera ex seed-di

Cyclanthera pedata, tendril, i. 697.

Cyclops, i. 122, 138, 153.

Cyclostigma, group of Gentians, conceal-
ment of honey, ii. 182.

Cydonia, fruit, ii. 436.

Cydonia Japonica, root-slips, ii. 27.

Cylindrocapsa, reproduction and structure,
ii. 650.

Cymbalaria, sub-genus of Saxifraga, ii. 346.

Cyme, modifications, i. 738, 746.

Cymodocea, pollen and pollination, ii. 104.

Cymodocea antarctica, bulbils, ii. 457.

— — dispersal of offshoots, ii. 807.

Cymopolia, structure, ii. 647.

Cynanchum, cotyledons, i. 608.

— scent, ii. 202.

Cynanchum fuscatum, plumed seeds, ii. 857.

Cynanchum Vincetoxicum, as host of Cron-

artium asclepiadeum, ii. 615.

—— downward pull of roots, i. 767.

Cynara scolymus, i. 189.

— — fruit, ii. 432.

Cynipedes and Oak-apples, ii. 537.

— escape of larva: from galls, ii. 538.

Cynips caput-meduse, gall on pericarp of
Quercus pubescens, ii. 540, 541.

Oynips Hartigii, bud-galls on Quercus sessi-
liflora, ii. 541.

Cynips Kollari, galls on Oak twig, ii. 541.

Cynips lucida, bud-galls on various Oaks, ii.
542.

Jod.

|, ii. 836.

Cynips polycera, bud-galls on Oak, ii. 541,
542, 550.

Cynoglossum, honey concealment, ii. 180.

— protogynous, ii. 310, 311.

Cynoglossum pictum, flower, ii. 180.

— — hooked fruit, ii. 871.

Cynomoriacee, ii. 762.

Cynomorium, life-history, i. 198.

— medicinal use, i. 198.

—sole European species of Balanophoreze
hosts, i. 198.

Cynomorium coccineum, i. 197.

Cyperacex, ii. 142.

— description, ii. 746.

— habitats, number of species, &c., ii. 748.

— pollen-grain, ii. 102.

Cyperus, germination, i. 605,

— switch-plants, i. 330,

Cyperus Papyrus. See Papyrus antiquorum,

Cypress. See Cupressus fastigiata.

Cypripedium, ii. 736.

— anthocyanin, i. 520.

— edible fioral hairs, ii. 170,

— stamens, ii. 253.

— stigmas, ii. 253.

— transference of pollen to insects, ii. 245.

Cypripedium Calceolus, duration of flowers,

ii. 214.

— — flower and bee, ii. 249.

—— pollination, ii. 245.

Cypripedium caudatum. See Paphiopedil-
ium caudatum.

Cypripedium insigne, &., duration of flower-
ing, ii. 214.

Cypris, i. 122, 153.

Oyrtandrez, scarlet flowers in, ii. 196.

Cyst, of Myxomycete plasmodium, ii. 619,

Cystoliths, of Boehmeria, optical effect, i.
285.

Cystopus candidus, ii. 22, 56, 670.

—— and Capsella Bursa-pastoris, ii, 525.

Cystosira, ii. 664.

— as host-plant, i. 77.

— luminosity, i. 388,

— on crabs, i. 77.

— structure, i. 590,

Oystosira barbata, where thrives best, i, 105.

Cytinaces, ii. 755,

Cytinus hypocistus, a parasite, i. 197, 201-204.

Cytisus, i. 250, 298, 330,

— cold resistance experiments, ii. 489.

Cytisus, insects and keel movements, ii. 252.
Cytisus Adami, alleged graft-hybrid, ii. 570.
Cytisus albus, protection of stomata from
moisture, i. 298.
Cytisus alpinus, and buds of C. Adami, ii.
570.

—— scent, ii. 201.
Cytisus australis, &., resistance to cold, ii.
489,

—— Rovigno, ii. 489.

Cytisus candicans, protection of stomata
from moisture, i. 298.

Cytisus Jacquinianus, and buds of C. Adami,
ii, 570.

Cytisus Laburnum, alluring floral tissue, ii.

— — flower-opening constant, i. 559.

—~— preparation of flowers for insect visits,
ii. 223.

— — seedling, i. 9.

— — seeds and cold, i. 544.

Cytisus radiatus, chlorenchyma and stomata,
i, 332.

— — details, i. 299.

— — geographical distribution, &c., i. 297.

—— green tissue, position, i. 471.

—— pr ion of ita from
297.

Cytisus spinosus, spines, i. 443, 449.

Cytoplasm, formative importance, ii. 494.

— views regarding, ii. 493.

isture, i.

D.

Dabeocia polifolia, geographical distribution,
i. 307.

Dacryomyces, shrivelling through loss of
water, i. 216.

Dactylis, pollination, ii. 142.

Deedalea quercina, ii. 21, 689.

Deemonorops hygrophilus, shoot apex, i. 676.

Daffodil family. See Amaryllidee.

Dahlia, propagation of crossings, ii. 556.

Dais cotonifolia, propagation, by root-slips,
ii. 27.

Dame’s Violet. See Hesperis.

Dammara. See Agathis.

Damping-off, ii. 670.

Dandeli See Tar officinale.

Dandruff, due to Microsporon furfur, i. 169.

Daphnales, description, ii. 752.

Daphne, pollen-grain, ii. 102.

— protection of pollen from wet, ii. 111.

— stigma, ii. 281.

Daphne alpina, scent, ii. 201, 203.

Daphne Blagayana, ii. 240, 752.

—— geographical distribution, ii. 902.

—— scent, ii. 203.

Daphne Laureola, scent, ii. 201.

— — sheltering of pollen, ii. 108.

—— spongy tissue of leaf, i. 279.

Daphne Mezereum, ii. 289, 753.

—— berry, ii. 427.

—— cross-fertilization, ii. 301.

— — fruiting branch, ii. 426.

— — hermaphrodite, ii. 296.

—— leaf-size and vertical range, i. 287.

—-—resemblance of flowering Apodanthes,

with host, to, i. 201.

— — thermal constants, i. 559.

Daphne Philippi, scent, ii. 201, 203, 209.

— — sheltering of pollen, ii. 108.

Daphne pontica, scent, ii, 201.

Daphne striata, scent, ii. 201, 203.

Darkness, germination and growth in, i. 518.

Darlingtonia Californica, general account,
i, 127.

Darwin and cross-fertilization, ii. 331.

— compares root-tip to simple brain, i. 776.

— Fertilization of Orchids, ii, 738.

— his influence on the study of botany, i. 16.

— theory of natural selection, i. 600.

yactis, circular mo’ ts, i. 684,

— habit, i. 248, 589.

— lime incrusted, i. 260.

Dasyclades, characteristics, ii, 647.
Dasylirion, habitat, i. 438.
— leaf, teeth and apex, i. 438.
Dasytes, honey-sucker, ii. 179,
— pollen devourer, ii. 167,
Date Palm. See Phenia dactylifera.
Date-plum. See Diospyros Lotus.
Datura, opening and closing, ii. 116.
— scent, i, 202.
Datura ceratocaula, size of flowers, ii. 185.
Datura Knightii, size of flowers, ii, 186.
Datura Metel, time open, ii. 213.
Datura Stramonium, fruit protection, ii, 442.
— — inequality of leaves and use, i. 422.
— — leaf-mosaic, i. 411.
— — night visitors, ii. 196.
—— odour, i. 431.
— — opening of flower, ii. 212, 213.
— — protection of pollen, ii. 113.
Daucus, peripheral flowers, ii. 186.
— umbel, day and night positions, i. 531.
Daucus Carota, downward pull of roots, i. 767.
—-— protection of stomata from moisture,
i, 295.
—— root, i. 760.
Daughter-cells, i. 578.
Davallia, protection of sporangia, ii, 13.
— sorus and indusium, ii. 706.
Day-lily. See Hemerocallis flava.
Deadly Nightshade. See Atropa Belladonna.
Dead Sea, blueness, i. 389.
De Candolle, i. 15.
— — table of classification, ii. 603.
Decay, putrefactive, a necessary condition
of life, i. 264.
Deciduous Cypress.
tichum.

Deciduous leaves, i. 347.

—— change of colour, i. 485.

— shrubs, anthocyanin, i. 520,

— stipules, i. 351,

Decurrent, leaf, i. 596.

— leaves, transpiration, i. 336.

Decussate leaves, i. 398.

Definitive nucleus, and endosperm forma-
tion, ii. 421.

Defoliation, i. 361.

Dehiscence of anthers in Grasses, ii. 91, 140.

Dehiscent dry fruit, ii. 429.

Deilaphila Euphorbie, victim of Araujia, ii.
260.

De Jussieu, A. L. and B., natural system of
classification, ii. 602.

De l’Ecluse, Charles (1526-1609). See Clusius.

Delphinium, foliage and light, i. 412.

— follicle, ii. 430.

— integument of ovule, ii. 81.

— morphological value of ovule, ii. 82.

— possible cause of doubling, ii. 554.

— preservation of colour in Egyptian graves,
i. 262.

Delphinium Ajacis, effect of mutilation, ii.

See Taxodium dis-

Delphinium cashmirianum, antholysis, ii.

Delphinium elatum, antholysis, ii. 83.

— — re-erection of inflorescence, i. 744.

Delphinium nudicauleand D. cashmirianum,
colour of flowers and hybrid, ii. 567.

Delpino, and difference of pollen in hetero-
styled flowers, ii. 405.

Dendrobiun, ii. 738.

—fimbriatum, discharge of pollinia, ii. 269,
270.

Denizen, application of term, i, 243.

Dentaria, peripheral flowers, ii. 186.

— scaly stem, i. 652.

— waxy coating, ii. 237.

Dentaria bulbifera, bulbils, ii. 460, 461.

—— habitat, ii. 110.

~—-— rhizome and light, i. 484.

Dentaria digitata, &c., leaf and light, i. 286.

— — habitat, ii. 110.

Dentaria enneaphyllos, habitat, ii. 110,

Dentate, i. 233.

De Plantis Libri, by Cesalpino, ii, 601.

Deposition of pollen, ii. 280.

INDEX,

al gy zoosporangia and zoospores, ii.
5.

Derivatives, of hydro-carbons, i. 454,

Dermatogen, and leaf origin, i. 649,

sia a and Dracunculus vulgaris, ii.
5.

— and indoloid scents, ii. 207.

Dermestes undulatus, and Dracunculus
Oreticus, ii. 165,

Dermogleea, ii. 621.

De Saussure, discovers red-snow, i. 38.

ve anoual and perennial plants in, i.

Desiccation, protection from, by salt incrusta-
tions, i. 236.
— protection of fruits from, ii. 449.
Desmanthus natans, swimming apparatus,
i. 669.
Desmid, division, ii. 655.
Desmids and specific constitution of proto-
plasm, ii. 492.
— cell-division, Pl. I., i. 576, 581.
— conjugation, ii. 55.
— habitat, i. 76; ii. 655.
— nutritive cycle, Pl. I., i. 466.
— sculpturing of wall, i. 577.
— striz of cell-walls, i. 568.
— swarms of, i. 585,
— various species, i. 492.
— zygospores, ii. 492.
Desmodium penduliflorum, leaf, diurnal posi-
tions, i. 534,
Desmoncus, spathe, i. 641.
Desmoncus polyanthus, shoot apex, i. 676.
Deterrent substances, i. 461.'
Development, highest, views concerning, ii.
598.
— of individual, and phyllogeny, ii. 608.
Dew, accumulation on under surface of
leaves, i. 291.
— and diurnal positions of leaves, i. 535,
— carbonic and nitric acid in, i. 370.
— on steppes and deserts, i. 235.
Dew-cup. See Alchemilla.
Dew-leaf. See Drosophyllum.
Dextrin, from starch, i. 465.
— from sugar, i. 506.
— osmotic behaviour of, i. 59.
— percentage composition, i. 454,
Diacalpe, protection of sporangia, ii, 13,
Diadromous venation, i. 633.
Dialypetala, of Endlicher, ii. 604,
Diandra, andreecium, ii. 736.
Diandria, Linnean class, ii. 86.
Dianthecia albimacula, pollinating Silene
nutans, ii. 155.
Dianthus, zstivation, ii. 210.
— and ancient crossing, ii. 555.
— and Campanula, colour-contrast, ii. 193,
— double-flowered hybrids, ii. 576.
— double flowers, ii. 80.
— favoured guests, ii. 230.
— honey protection, ii. 238,
— hybridization and flower colours, ii. 568,
— hybrids, ii. 584.
— — autogamous propagation, ii. 579.
— massing of flowers, ii. 186.
— nectaries, ii. 176.
— of Mediterranean, waxy bloom of leaves,
i. 312.
— pollen-grains, ii. 99, 102.
— propagation by cuttings, i. 251.
— substratum, ii. 498.
— transition from stamens to petals, ii. 86.
Dianthus alpinus and D. superbus, hybrid
of, ii. 563,
— — cultural experiments, ii. 513.
Dianthus Carthusianorum, pollen-grains, ii.
98.
—— thermal constants, i. 559.
Dianthus Caryophyllus, mechanical tissue
arrangement, i. 730.
— — possible cause of doubling, ii. 554.
— — scent, ii. 200.
Dianthus deltoides, cultural experiments,
sources of error, ii. 513.
Dianthus glacialis, zestivation, ii. 210.

943

Dianthus glacialis, autogamy, fi. 337, 364.

— — distribution of sexes, ii. 298.

Dianthus inodorus (sylvestris), elevation and
coloration, ii. 511.

Dianthus neglectus, eestivation, ii, 210.

— — autogamy, ii. 364.

Dianthus (Enipontanus, hybrid, ii. 563.

Dianthus plumarius, possible cause of doub-

ling, ii. 554.

—— scent, ii. 200.

Dianthus polymorphus, Pl. VI.

Dianthus prolifer, distribution of sexes, ii. 298.

~— — duration of flowering, ii. 213.

Dianthus superbus, scent, ii. 200.

Dianthus viscidus, source of specific name,
ii. 235,

Diapensia Lapponica, Arctic, absence of
hairs, i. 316.

Diapensiacez, ii. 768.

Diastase, action on starch, i. 459, 465.

— distribution in plant, i. 483.

Diastole. See Vacuole.

Diastrophus Scabiose, bud-galls on Cen-
taurea, ii. 543.

Diatom, description, i. 261; ii. 625.

Diatom-deposits, ii. 627.

Diatom-earth, ii. 614.

Diatomacez, as prey of Aldrovandia, i. 153.

— cell-membrane of, i. 40.

— conjugation, ii. 55.

— epiphytic, non-parasitic, i. 77, 160.

— geographical distribution, ii. 626.

— movements of, i. 39; ii, 626.

— preparation of siliceous skeletons, i. 67

— propagation, &c., ii. 626.

— resistance to cold, i. 542.

— silicic acid in, i. 67, 70.

— social groups, i. 585.

— some attached, some free, i. 40.

— structure and light, i. 388.

— swarms and filaments, i. 585, 586.

Diatomin, pigment of Diatoms, ii. 625.

Diavolezza, Switzerland, soil and air tem-
peratures, i, 525.

Dichogamous flowers, ii. 307, 310.

Dichogamy and hybridization, ii. 314.

— in Saxifraga rotundifolia, ii. 308.

— nature of, ii. 134, 309.

Dicksonia, aérial roots, i. 753,

— caudex, ii. 705, 714.

— sorus and indusium, ii. 708.

Dicksonia antarctica, aérial roots, i. 714.

Diclines irregulares, of de Jussieu, ii. 602.

Dicotyledones, ii. 728.

— definition of, earlier subdivisions, i. 15.

— distinctive characters, ii. 748.

— of de Jussieu, ii. 602.

— sub-classes, ii. 748.

Dicotyledons, ii. 617.

Dicranodontium aristatum, vegetative pro-
pagation, ii. 458,

Dicranodontium longirostre, habitat, i. 109.

Dicranum, absorptive felt, i. 86.

Dicranum congestum, habitat, i. 109.

Dicranum elongatum, habitat, i. 113.

Dicranum Sauteri, exclusive habitat, i. 119.

Dicranum scoparium, habitat, i. 109.

Dictamnus, stamens as insect platform, ii.
225.

Dictamnus fraxinella, scent, ii. 203.

Dictydium cernuum, sporangia, ii. 491, 618.

Dictydium umbilicatum, life-history, i. 572.

Dictyodromous, venation, i. 630.

Dictyonema form, of Cora, ii. 695.

Dictyophora phalloidea, ii. 691.

Dictyospherium, life-cycle, ii. 636.

Didymium, i. 573.

Didymodon ruber, parthenogenesis, ii. 464.

Diervilla, twisting of internodes, i. 417.

Diervilla Canadensis, erect and pendent
twigs, i. 417.

Diervilla rosea, ovules and attraction of pol-
len-tubes, ii, 414.

Diffusion, through membrane and free, i. 59.

Digestion, by Nepenthes pitcher, i. 135,

—in Aldrovandia, i. 153.

— of prey, by Dionza, i. 150,

944,

Digitalis, and insect visits, ii. 222.

— as insect shelter, ii. 163.

— bees and pollen, ii. 247.

— corolla and autogamy, ii. 367.

— effect of mutilation, ii. 517.

— one-sided raceme, ii. 224.

— ovary, ii. 76.

— protandrous, ii. 311.

— protection of pollen, ii. 118.

— spurred hybrids, ii. 576.

Digitalis grandiflora, attraction of foreign
pollen-tubes by ovules, ii. 414.

Digitalis lutescens, sheltering of pollen, il.
110.

Digitalis ochroleuca, elevation and colora-
tion, ii. 511.

Digitalis purpurea, duration of flowering, ii.
213.

— — flower-opening constant, i. 559.

— — temperature experiments, i. 502.

Dimorphic fruits, ii. 878.

Dinifera, group of Dinoflagellata, ii. 625.

Dinoflagellata, animal affinities, ii. 620.

— description, ii. 625.

Dicecious flowers, and wind-fertilization, ii,
134.

— plant, type, ii. 299.

— plants and hybridization, ii. 314.

—— majority protogynous, ii. 313.

—— pollination, ii. 136.

Dionea, advantage of carnivorous habit
questioned, i. 157.

— leaf compared to that of Drosera, i. 151.

— ovary, ii. 75.

Dionza muscipula, i. 148, 150, 340, 536.

Dioon, Central America, ii. 720.

Dioscorea, mechanical tissue, i. 732.

— pollen-grains, ii. 99.

— seed-dispersal, ii, 852.

Dioscorides, i. 4.

Diospyros Lotus, imperfect flowers, ii. 294.

Diphtheria, i. 163, 506; ii. 624.

Diplochlamydex, of De Candolle, ii. 603.

Diplosis, escape of larve from galls, ii, 538.

Diplosis botularia, gall on Ash leaf, ii. 534.

Diplosis tremule, gall on Aspen petiole, ii.
540

Diplotaxis, dehiscence of pollen-sacs, ii. 93,

— twisting of anther, ii. 250.

Dipsacee, ii. 352, 765.

— distribution of sexes, ii. 298.

— insects and pollen, ii. 244.

— pollen deposition in, ii. 278.

— water receptacles, i. 156.

Dipsacus, protective water basins, ii. 234.

Dipsacus laciniatus, water-receptacles, i.
239, 242.

Diptera, gall formation, ii. 527.

Diptero-cecidia, gnat-galls, ii. 528.

Disa, 8. Africa, ii. 737.

Disciflore, ii. 777.

Discolichenes, characters, ii. 693.

— subdivision, ii. 694.

Discomycetes, i. 168; ii. 19, 676, 682, 683.

— as lichen-fungi, ii. 693.

— mode of attack, i. 163,

Discopodium, i. 746.

Disc-shaped receptacle, i. 746.

Disease, due to bacteria, i. 163.

of plants, ition,

— — general remarks, ii. 832.

Displacement, of leaf, by torsion, i. 407.

— of whorls, i. 397.

Dissemination and germination, i. 614.

—of respective partners of Lichen-thallus,
i. 246.

Distribution and climate, ii. 879.

— conditions affecting, ii. 2.

— of plants, and heat, i. 527.

Divergence of leaves, i. 397, 403.

Division, of cells, i. 576.

— of labour, i. 251, 367, 561, 594.

Doctrine of prolepsis, i. 8.

Dodder. See Cuscuta.

Dodecatheon, autogamy, ii. 333.

INDEX.

Dog’s Mercury. See Mercurialis perennis.

Dog’s-tooth Violet. See Erythroniwm Dens-
Canis.

Dogwood. See Cornus sanguinea.

Dolomite, attacked by Lichens, i. 257.

— prevalence of, i. 83.

Doria, pericarp mucilage, i. 615.

Dormant buds, ii. 30.

— eye, nature of, ii. 30, 34.

Doronicum, artificially induced drooping, ii.
123,

— protection of pollen, ii. 120.

Dor cordat dick y, ii, 312.

Doronicum glaciale, geitonogamy, ii. 322.

Doronicum Pardalianches, opening
flowers and growth, ii. 220.

Doronicum scorpioides, geitonogamy, ii.

of

Dorsal suture, of follicle, &., ii. 430.

Dorsteniaceae, ii. 758.

— on trees and rocks, i. 156, 108,

— seed-dispersal, ii. 835.

Dorycnium decumbens, ash of, i. 69.

— — isolated colonies, i. 528.

Dorycnium herbaceum, seed-dispersal, ii. 833.

Doryphora, stamens, ii. 87, 89.

— staminal stipules, ii. 89.

Double flowers, i. 646.

—— abortive pollen, ii. 403.

— — due to gall-mites, ii. 548,

— — long fresh, ii. 287.

— — origin, ii. 86.

Douglas Fir. See Tsuga Douglasii.

Doum Palm. See Hyphene thebaica,

Draba, hybridization, ii. 584.

— indumenta of hybrids, ii. 564.

— nectary, ii. 175.

Draba aizoides, autogamy, ii. 337.

— — colour-contrast in inflorescence, ii. 192.

— — protection of pollen, ii. 121.

Draba alpina, absence of hairs, ii. 316.

Draba borealis, autogamy, ii. 339.

Draba Hoppeana, hybrid of D. Fladnizensis
x D. Carinthiaca, ii. 586.

Draba repens, unfruitful artificial autogamy,
ii. 406.

Draba stellata, habitat and hairiness, i. 315.

Draba Thomasii, hairs, i. 321.

Draba tomentosa, habitat and hairiness, i.
315.

Draba verna, autogamy, ii. 339.

— — colour-contrast in inflorescence, ii. 192.

Draceena, mode of growth, i. 660.

Draczena Draco, geographical distribution,

&e., ii. 731.

——of Orotava, age and dimensions, i. 714,
720.

Dracocephalum, pericarp mucilage, i. 615.

Dracocephalum Ruyschianum, elevation and
coloration, ii. 511.

Dracontium, tubers, ii. 745.

Dracunculus creticus, and carrion-flies and

beetles, ii. 208.

—— &c., insect visitors, ii. 165.

Dragon-tree. See Dracena Draco.

D naldia, differ ion of thallus, ii.
620.

— swarm-spores, i. 29, 30.

— thallus, ii. 652.

Drimys, pollen tetrads, ii. 97.

Dropwort. See Spirea Filipendula.

Drosera, Pl. II., i. 154, 158, 237, 536.

— arrangement of leaves, &c., i. 144.

— autogamy, ii. 356.

— comparison of leaf with that of Dionsa,
i. 151.

— digestion of prey, i. 146.

— duration of blossoming, ii. 214.

— glands, i. 144.

— great number of species, i, 143, 148.

— nectaries, ii, 178.

— ovary, ii. 75.

— ovule, ii. 82.

— pollen-sacs, ii. 89.

— stigma, ii. 282.

— tentacles and their movements, i. 145.

Drosera intermedia, antholysis, ii. 83.

Drosera longifolia, duration of blossoming,
ii. 214.

— — flower, ii. 279.

— — opening and closing, ii. 212.

— — stigma, ii. 279.

— — weather and autogamy, ii. 391.

Drosera obovata, hybrid of D. longifolia x
D. rotundifolia, ii. 586.

Drosera rotundifolia, carnivorous, habitat,
i, 143.

Droseraceze, genera of, i. 148.

— movements of stamens, ii. 250

Drosophyllum, i. 148.

— description, i. 154.

— epiphyllous secretory glands, i. 157.

— ovary, ii. 75.

— used as lime-twigs, i. 155.

Drosophyllum lusitanicum, i. 155; ii. 237.

Drupaceous nut, nature of, ii. 429.

— — of Fumaria, ii. 427.

Drupe, nature of, ii. 428.

Dryadex, protection of pollen, ii. 118.

Dryandra, inflorescence, ii. 230.

— pollination, ii. 230.

Dryandra floribunda, protection of stomata
from moisture, i. 296, 298.

Dryas, receptacle and carpels, ii. 76.

Dryas octopetala, i. 303, 304.

— — autogamy in, ii. 381.

—— distribution of sexes, ii. 298

—— procumbent habit, i. 662.

Dryness, preventive of decay, i. 262.

— seed protection against, ii. 447.

Dryobalanops, seed-dispersal, ii. 854.

Dryoterus terminalis, bud-galls on Oak, ii.
543.

Dry-rot, i. 508,

Dry-rot Fungus. See Merulius lacrymans.
Du Bois Raymond, compares dynamical
with morphological description, i. 17.

Duckweed. See Lemna.

Ducts, for collecting water, in foliage-leaves,
i. 231

Dudresnaya coccinea, antheridia, &c., ii. 61.

— — fertilization and fruit formation, ii. 53.

Dulcite, alluring, i. 461.

Dung- beetles, and colour and odour of
flowers, ii, 197.

Durmast. See Quercus sessiliflora.

Durvillea, habit, ii. 664.

Durvillza utilis, edible, ii. 665.

Dust, aérial, chemical substances in, i, 81.

— circulation of, i. 81.

— collection by Mosses and Lichens, &c., i.

— in snow and air, i. 79.

— meteoric, nature of, i. 80.

— organic, food of rotifers, ii. 255.

Dutch Rush. See Equisetum hiemale.

Duvaua longifolia, and gall of Cecidoses
Eremite, ii. 534, 537, 539.

Dwarf Elder. See Sambucus Ebulus.

— Leek. See Allium Chamemoly.

— male, of @dogonium, ii. 651.

— Palm. See Chamerops humilis,

E.

Earth, properties and structure, i. 82-84.

Earth-stars. See Geaster.

Earwigs, protection against, ii. 445.

East Indian Archipelago, Henslowia in, i. 204.

Ebenacex, ii. 768.

Ecballium Elaterium, seed-dispersal, ii. 834.

Echeveria, epiphyllous buds, ii. 40.

— leaf-rosettes, i. 410.

Echeverias, and cold, i. 543.

— Mexican, aqueous tissue, i. 328.

Echinocactus, i. 327.

—and night visitors, ii. 196.

— cross-fertilization, ii. 301.

— spines, i, 446,

Echinocactus horizontalis, ii. 787.

Echinocactus oxygonus, &c., size of flowers,
ii, 186.

Echinocactus Tetani, scent, il. 201,

— — time open, ii, 213,

Echinophora spinosa, ‘'spinose leaves ”, 1,438,
Echinops, spiny leaves, i, 438.

Echinopsis, autogamy, ii. 347.

Echinopsis cristata, size of flowers, ii, 185,
Echium, bristles, i. 441.

— cross-fertilization, ii. 301.

— insects and pollen, ii. 245,

— protandrous, ii, 311.

— stamens as insect platform, fi. 225.

— unfolding of inflorescence, i. 744.

Echium Italicum, bristles, i, 439.

Echium vulgare, pollen-grains, ii. 97,
Ectocarpaces, structure, &e., ii, 661.
Ectocarpus, host of Entoderma, ii. 652.
Ectocarpus siliculosus, fertilization, ii, 661.
Ectoplasm, i. 34, 57, 72, 569.
Edel See Ar isia Mutelti
Edelweiss. See Gnaphalium Leontopodium.
Edelweiss of Himalayas, i. 316.
Egg-apparatus=archegonium, ii. 478.

—— constituents, ii. 416.

Egg-cell, behaviour in fertilization, ii. 417.
—— of Fern, ii. 472.

—— development after fertilization, ii. 475.

INDEX,

Embryogeny, of Selaginella, ii. 715,

Embryonic cell, ii. 417,

Embryo-sac, i. 598,

— and contents, ii, 416.

— homology, ii. 478, 717.

— of Gymnosperms, ii. 418,

— of Monotropa, ii. 417.

Emericella variecolor, a gasterolichen, ii. 695,

“Empalement” or calyx, ii. 210,

Empetraces, ii, 768,

Empetrum, and animals, i. 432,

— mycorhiza, i. 251.

— rolled leaf of, i. 300.

Empetrum nigrum, i. 305, 490.

— — cuticular rods on leaves, i, 302.

Empis, sheltering in flowers, ii, 163.

Empleurum serrulatum, stamen, ii. 87.

Empusa, spore-dispersal, ii. 824.

Empusa Musee, life-cycle, ii. 672.

— — mould on flies, i. 168,

Enmulsin, i. 465.

Enalus, ii. 739.

Enalus ie geographical distribution,
ii. 133.

—— pollination, ii. 133,

E halartos, cotyledon in germination, i.

—— with spermatozoids, of Fucus vesicu-
losus, ii. 664.

Egg-cells, in Gymnosperms, ii, 418.

— — of Fucus vesiculosus, discharge, ii. 663.

Eggs, of Chlorophyces, ii. 628.

Egyptian desert regions, hairiness of plants,
i, 318,

— graves, preservation of fruits, &., in, i.
262,

Eichler, ii. 605, 616.

Eisménuer, of May, i. 539.

Elzagnus, hair-scales, i. 322, 324; ii. 752.

— scent, ii. 209.

Elaphomyces, forms mycorhiza, ii. 678.

— fruit, ii. 678.

Elaters, of Anthocerotaces, ii. 698.

— of Equisetum, ii. 712, 713.

— of Hepaticw, function, ii. 16, 696, 813.

Elatine Alsinastrum, aérial and submerged
leaves, ii. 505.

Elbe, self-purification, i. 265.

Elder. See Sambucus nigra.

— Dwarf. See Sambucus Ebulus.

— Red-berried. See Sambucus racemosa.

— scent, ii, 202.

Eleanthus, flour-like coating on lip, ii. 169.

Electric phenomena, in Dionzea, i. 151.

Elephant, agent in dispersion of Rafflesia
seeds, i. 199.

Eleutheropetale, of Braun, ii. 605.

Elevation and colour, ii. 511.

—and date of blossoming, &c., i. 525, 526,

Elm. See Ulmua.

Elodea, i. 77, 665; ii. 739.

— effect of heat on, i. 553.

Elodea Canadensis, pollination, ti. 133,

—— propagation by offshoots, ii. 457.

Elvend Kuh, features of vegetation, ii. 457.

Elymus, pollination, ii. 142.

Elymus mollis, and cold, i. 547.

Embryo, detachment from parent, ii. 450.

— development in Phanerogams, ii, 420.

— differentiation, i. 596, 750.

— equipment for journey, ii. 423.

— meaning of term, ii. 47.

— nutrition, i. 598 et seq.

— of Aspergillez, ii. 60.

— of Centrospermss, ii. 750.

— of Chara, ii. 64.

— of Cynomorium, i. 198.

— of Erysiphes, ii. 59.

— of Ferns, ii. 68.

— of Graminea, i. 604.

— of Orobanchez, i. 184.

— of parasitic Phanerogams, i. 176, 183.

—of Rhizophora, nutrition, germination,
&e., i, 602.

— protection and climate, ii. 447.

— protective coverings, i. 601.

— undifferentiated, i. 647.

Embryo-cell of Angiosperms, ii, 421.

Vou. IT.

945

Ephedra, i. 376.

— chlorenchyma, i. 332.

— description and details, ii. 726,

— dicecious, ii, 299.

— egg-cells and fertilization, ii. 418,

— flowering at Kew, ii. 474.

— ovule and fertilization, ii. 415.

— reserve-buds, ii. 33.

— seed envelope, ii. 441.

—various species, protection of stomata
from moisture, i. 296.

Ephemeral flowers, ii. 212,

— — protogyny in, ii. 310.

Ephydatia (Spongilla) fluviatilis and Trento-
pohlia spongophila, ii? 653,

Epicotyl, i. 596.

Epidemics, cause of, i. 506.

Epidendrez, ii. 738.

Epidendrum elongatum, amount of water-
absorption in moist air, i. 222.

Epidendrum Lindleyanum, duration of flow-
ering, ii. 214.

Epidermis, i. 469.

— as conducting apparatus, i. 369.

—cells, adaptation to function, i. 369

— functi in bifacial leaf, i. 370.

606.

— spinose leaves, i. 438,

Encysted plasmodium of Myxomycetes, ii.
619.

Endemic diseases, cause of, i. 506.

— species, examples, ti. 882.

— — importance of, ii. 903.

—— liability to extinction, ii. 901,

Endlicher, system of, ii. 603, 604.

Endocarpon, a pyrenolichen, ii. 695.

Endocarpon miniatum, situation on a marble
column, i. 247.

Endogenz, of De Candolle, ii. 603.

Endophyllum Sempervivi, on House-leek, ii.
523.

Endoplasm, i. 34.

Endosmosis. See Osmosis.

Endosperm, i. 598.

— absence in Gourd, i. 610.

— homology, ii. 717.

— of Gymnosperms, ii. 418.

— origin and nature, ii. 421.

Endosphzracex, description, ii. 637, 638.

Endospore, of Bacteria, ii. 623.

Energy and fermentation; i. 509.

— conversion of, by plant, i. 378.

— kinetic, i. 492.

— of respiration, measurement, i. 495,

— potential, i. 492.

— transformation by plant, i. 492.

England, flora of, i. 6.

Engler, ii. 605.

Ennobling, application of term, i. 213.

— methods of, i. 214.

— success in, ii. 554,

Entada gingolobium, stranded in Norway,
ii. 879.

Enteromorpha, range, i. 390.

— structure, &c., ii. 648.

Entoderma, endophytic, ii. 652.

Entomophilous Arctic and other plants,
percentage of autogamous species, ii. 400.

— plants, ii, 129, 583.

Entomophthorez, ii. 672.

Entyloma Aschersonii, gail on Helichrysum,
ii. 521.

Entyloma Magnusii, gall on Gnaphalium, ii.
521.

Environment and origin of species, ii. 596.

Enzyme-like poison of stinging hairs, i. 441.

Enzymes and gall formation, ii. 551,

— nature, function, &c., i. 464, 465.

Epacridaces, pollen tetrads, ii. 97.

Epacrides, i. 306; ii. 768.

—and animals, i, 432.

— mycorhiza on, i. 91, 251.

— symbiosis with different Fungi in different
localities, i. 252.

Epacris, pollen tetrads, ii. 97.

Ephebe Kerneri, ii. 694.

—— a gelatinous Lichen, i. 244.

— in rolled leaves, i. 302.

— many-layered, i. 369.

— of leaf, wettable and non-wettable parts, i.
230.

— of leaves, in relation to transpiration, i.
226, 280, 309.
— of succulents, i, 329,
— of young stem, i. 719.
— transmission of carbonic acid, i. 368.
Epilobium, alternation of cross- and self-
pollination, ii. 335,
— autogamy, ii. 335, 352.
— grooving of stem, i.'95.
— hybrids, ii. 584.
— pollen, ii. 104,
— seed-hairs, ii. 424,
— thin places of pollen-grain, ii. 102.
Epilobium alsinefolium and E. palustre,
established hybrid of, ii. 591.
Epilobium angustifolium, autogamy, ii. 354.
—— inflorescence, ii. 309, 354.
—— nectary concealment, ii. 181.
— — opening of flower, ii. 212.
—— ovary, ii. 77.
—— pollen deposition, ii. 278.
——pollen-grains with viscin threads, ii.
101.
— — protandrous flowers, ii. 309.
—— re-erection of inflorescence, i. 744.
— — subterranean runners, ii. 453.
— — visited by bees, ii. 195.
Epilobium collinum, duration of flowering,
ii, 213.
— — opening of flower, ii. 212.
—— plumed seeds, ii. 858.
Epilobium hirsutum, cohering pollen-grains,
ii. 97. :
—— colour-contrast of flowers, ii. 189.
—— protection of pollen, ii. 121.
Epilobium montanum, anthocyanin, i. 520.
—— cohering pollen-grains, ii. 97.
—— colour-contrast of flower, ii. 189.
—— protection of pollen, ii. 121.
Epilobium parviflorum, autogamy, ii. 335.
Epilobium roseum, protection of pollen, ii
121.
Epilobium scaturiginum, an established
wild hybrid, ii. 591.
Epimedium, anthocyanin, i. 484.
— dehiscence of pollen-sacs, ii. 93, 95.
— flower and autogamy, ii. 349.
— nectaries, ii. 178.
Epimedium alpinum, autogamy, ii. 347.
— — flower, ii. 236.
Epipactis, habitat and foliage, i. 110,
—nectary, ii. 176.
Epipactis and Cephalanthera, hybridization,
ii. 583.
Epipactis latifolia, abortive stamens, ii. 253.
— — pollination, ii. 254, 255, 283.
Epipactis microphylla, radical buds, ii. 28.

110

946

Epipactis speciosa, and other hybrids,
583.

=H

Epiphragm, of Polytrichum peristome, i
703.

Epiphyllous buds, ii. 37, 40, 44.
— shoots, ii. 37.
Epiphyte, meaning of term, i. 56.
Epiphytes, adventitious roots, i. 751.
— aérial roots, i. 753.
— favourite bark, i. 720.
— formerly treated as parasites, i. 159.
— mode of growth of roots, rhizoids,
hypha, i. 115.
— nutrition, i. 116.
— on epiphytes, i. 416.
Epiphytism, among Marine Alga, i. 161.
Epipogium, i. 184, 655.
— absorbent cells, i. 766.
— nectary, ii. 176.
— pollen deposition and retention, ii, 284.
— position of labellum, ii. 224.
— scaly stem, i. 652.
Epipogium aphyllun, ii. 201.
—— absorptive cells and food-absorption, i.
114,
— — description, i. 111.
—— flower, &c., ii. 226.
—— habit, ii. 737.
—— habitat and foliage, i. 110.
—— pollination, ii. 257.
—— rapid growth of flowering stem, i. 118.
Episcia bicolor, epiphyllous buds, ii. 43,
Epithemia, cold resistance, i. 542.
Equisetacex, alternation of generations, ii.
476.
— antheridia and fertilization, ii. 68,
— apical-cell, i. 579.
— description, ii. 711.
— Paleozoic, ii. 612.
— prothallium, ii. 68.
— sporangia and spore-formation, ii. 14.
Equisetales, ii. 711.
— fossil remains, ii. 713.
— sporophyte characteristics, ii. 704.
Equisetum, and animals, i. 432.
— arrangement of stomata, i. 280.
— elaters, function of, ii. 815.
— number of species, ii. 711,
— silica in, ii. 712,
— silicic acid in, i. 67.
— switch-plants, i. 330.
Equisetum arvense and E. limosum, hybrid
of, ii. 582.
— — fertile shoot, ii. 712.
— — spores with elaters, ii. '712.
—— sterile and fertile shoots, i. 653; ii. 14,
476.
Equisetum giganteum, &c., height, ii. 712.
Equisetum hiemale, commercial use, ii. 713,
Equisetum inundatum, hybrid, ii. 582.
Equisetum limosum, necessary soil, ii. 612.
Equisetum sylvaticum, ii. 14, 712.
Equisetum Telmateja, shoot, kinds of, i. 653.
Equitant leaves, i. 336.
Eranthis, colour of sepals, ii. 183,
— germination, i. 622.
— movements of stamens, ii. 250.
— nectaries, ii, 179. :
— opening of flower and growth, ii. 220.
— protection of pollen, ii. 112, 114.
Eranthis hiemalis, duration of flowering, ii,
213.
Eremospheera, ii. 636,
Eremurus, aphide mimicry, ii. 327.
— behaviour of styles, i. 740.
— geitonogamy, ii. 326,
Eremurus altaicus, &c., alluring tissue, ii.
171.
Eremurus Caucasicus, inflorescence, ii. 309.
Ergot of Rye. See Claviceps purpurea.
Ergotism, ii, 681.
Erica, dispute about name, i. 5.
— hybridization in, ii. 330, 585.
— pollen sprinkling, ii. 275,
— pollen tetrads, ii. 97, 104.
— sticky stigmas, ii. 282. y
~— suitable substratum, i. 250; ii, 498. !

i

INDEX.

Erica arborea and galls of Cecidomyia
Ericz, ii. 547.

—— distribution in Istria, i. 306.

Erica caffra, details of leaves, i. 301, 302.

Erica carnea and galls of Cecidomyia Ericz,

ii. 547.

— — depth of flower, ii. 180.

—— geitonogamy, ii. 328, 329.

— — inflorescence and flowers, ii. 329.

— — pollination, ii. 129.

— — stamen, ii. 329.

Erica cinerea, i. 305.

Erica Mackayi, hybrid of E.
Tetralix, ii. 586.

Erica Tetralix, i. 305.

Erica vestita, rolled leaves, i. 301.

Ericacee, ii. 768.

— Cape, number and variety, i. 306.

— dichogamy in, ii. 312.

— geitonogamy in, ii. 328.

— hair-like cuticular filaments, i. 310.

— heterostylism in, ii. 398.

— hybrids among, ii. 585.

—in Alps, i. 489.

— mycorhiza in, i. 91, 251.

— pollen tetrads, ii. 97.

Erigeron, autogamy, ii. 359.

— natural hybrids, ii. 585.

Erigeron alpinum, dichogamy, ii. 312.

Erineum quercinum, former gall-name, ii.
529.

Eriodendron, fruit and seed, ii. 423, 424.

Eriodendron caribzsum, buttress-roots, i. 756.

Eriophorum, ii. 748.

Eriophorum angustifolium, plumed fruits, ii.

ciliaris x E.

Eriophorum vaginatum, difficulty of culti-
vation, i. 113.
Eristalis arbustorum, on Phlox and Solidago,
ii, 166.
Erodium, fruit-anchoring, i. 616.
— fruit-planting, i. 619.
— nectaries, ii. 175.
Erodium Cicutarium, cotyledons, i. 621.
— — opening and closing, ii. 212.
Ervum, behaviour to own and foreign pollen,
ii. 407.
— tendrils, i. 692.
Eryngium, geitonogamy, ii. 323.
— pollen deposition, ii. 278.
— protogynous, ii. 311.
Eryngium alpinum, coloured bracts, ii. 183,
Eryngium amethystinum, at Trieste, i. 451.
— — coloured inflorescence stalks, ii. 185.
— — spinose leaves, i. 438.
Eryngium bre lizefolium, &c., gec
distribution, i. 438.
—— leaves, i. 438.
Eryngium campestre and cattle, i. 451.
Eryngium creticum, coloured inflorescence
stalks, ii. 185.
Erysimum, hairs, i. 321.
Erysimum odoratum, scent, ii. 202.
Erysiphe, development of embryo, ii. 60.
Erysiphe Tuckeri, destructive vine parasite,
i. 166; ii. 677.
Erysiphes, asci and ascospores, ii. 19,
— description, ii. 677.
— fertilization, &c., ii. 59.
Erythrea, alluring petals, ii, 170.
— dehiscence of pollen-sacs, ii 93,
— grooving of stem, i. 95.
— opening of flower, ii, 212.
— protection of pollen, ii. 113.
— stigma, ii. 281.
Erythreea Centaurium, duration of flowering,
ii, 213,
——stamen, ii. 91.
Erythreea pulchella, corolla and autogamy,
ii, 366.
— — duration of flowering, ii. 213.
Erythrina crista-galli, &c., scarlet flower, ii.
96.

hical

Erythronium, ii. 731.
— protogynous, ii. 311.

| — cactiform, i. 327,

Erythrophyll, of Floridez, fluorescence, ii.
388.

Erythrynez, prickles, i. 433.

Eschscholtzia, flower shape, ii. 167

— heterostyly, ii. 303.

— seed-dispersal, ii. 838,

Eschscholtzia Californica, cotyledons, i. 621.
—— duration of flowering, ii. 213,

, — — heterostyly, ii. 302.
| —— protection of pollen from ‘rain, ii. 112,

114.

“Espigo de sangue”, Brazilian name of
Helosis, i. 193.

Ethane, i. 453.

Ether and radiation, i, 518,

Ethereal oils, i. 461.

Euactis, circular movements, i. 684.

— habit, i. 589.

— lime-incrusted, i. 260.

Euastropsis, structure and reproduction, ii.

9,

Euastrum oblongum, ii. 492, 655.
Eucalyptus, bark, i. 720.

— capsule, ii. 431, 432, 449.

— unprotected pollen, ii. 107.

— vertical leaf-blades, i. 335.
Eucalyptus amygdalina, i. 723.
Eucalyptus coriaceus, cotyledons, i. 621.

| Eucalyptus globulus, flower-bud and fruit,

ii. 782.
—— variety of foliage, ii. 471.
Eucalyptus orientalis, cotyledons, i. 621.
Eudorina, life-history, ii. 633.
Eugenia, venation, i. 631.
Eugenol. See Oit of cloves.
Euglena and Polyphagus Euglena, ii. 671.

| — saprophytic, i. 103.

Euglenz, i. 63.

— food-absorption, i. 113.

— various habitats, i. 105.

Euglenopsis, life-cycle, ii. 636.

Eulalia japonica, protection of stomata from
moisture, i. 294.

— — weather-cock leaves, i. 427.

Euonymus, aril, ii. 425.

— honey and pollination, ii. 173, 179.

Euonymus Europeus, i. 487; ii. 173.

—— flowering branch, ii. 778.

Euonymus yerrucosus, i. 487.

— — mite-galls, ii, 529,

Eupatorium cannabinum, &., geitonogamy,
ii. 319, 320.

Euphorbia, axillary buds, ii. 29.

— filament of stamen, ii. 87.

— hybrids, ii. 584.

— laticiferous tubes, i. 470.

— nectaries, ii. 173.

— ovary, ii. 76.

— pollen-grain, ii. 100.

— protection of pollen, ii. 124,

— protogynous, ii. 313,

— starch, i. 459.

Euphorbia amygdaloides, in, i. 520,

Euphorbia ccerulescens, spines, i. 446,

Euphorbia Cyparissias, and galls of Ceci-
domyia Euphorbia, ii. 547.

—— and Uromyces Pisi, ii. 525.

—— radical buds, ii. 28.

—— scent, ii. 202.

Euphorbia dulcis, scaly stem, i. 652.

Euphorbia Peplus and vulgaris, buds on

hypocotyl, ii. 28.
Euphorbia spinosa, spinosity, i. 444.
Euphorbia splendens and polychroma, col-
oured bracts, ii. 183.
Euphorbiacess, ii. 756.

\

— — geographical distribution, i. 328.
— — habitat, i. 328.

— — organization, i. 328.

— — oxalate of lime, i. 328.

— dehiscence of pollen-sacs, ii, 92.

— distribution of sexes, ii, 297.

— moncecious, protogynous, ii. 313.
— odourless, i. 431.

Erythronium Dens-Canis, leaf-bud,

— part is in, ii. 465.

from soil, i. 640.

— “Phrygian”, i. 444,

Euphorbiaces, phyllocladous, i. 334.
— spines, i, 446,

— staminal filaments, ii, 88,

— stinging hairs, i. 441.

Euphrasia, abundance in mountainous dis- |

tricts, i. 178.
— geographical distribution, i, 176,
— injury to pastures, i. 179.
— parasitic, i. 176, 243,
— protection of pollen from wet, ii 110.
— variability of floral colour, ii. 569.
— venation, i. 631.
Euphrasia minima, autogamy, ii. 253, 351.
‘Euphrasia officinalis, sheltering of pollen, ii.

Euphrasia Rostkoviana, &c., corolla and auto-
gamy, ii. 366.
Euriops, pericarp mucilage, i. 615.
European lianes, i. 670.
Eurotium, i. 263, 677.
— fermentative action, i. 508.
— mycelium and reproductive organs, ii. 679.
Evryangium Sumbul, geographical distribu-
tion, flowering, i. 745,
chanical tissue ar
—— musk-scented leaves, ii. 199.
Evaporation, in plants, general considera-
tions, i. 226.
Evax, hairiness, i. 317.
Evergreen leaves, preparation for resting
period, i. 485.
Evergreens, cuticle usually thick, i. 310.
Evolution, discussion on, ii. 609.
— of plants and classification, ii. 607.
Ex-albuminous, applied to seed, ii. 421.
Excoriation of capitate celis during imbibi-
tion of water, i. 229.
Excretion, by discoid glands, of Alpine Rose,
i, 232.
— from water-absorbing apparatus of Aspen,
i, 238,
Excretions, viscous,
plants, i. 461.
Exidia, appearance, i. 112.
Existence, struggle for, ii. 600.
Exoascacez, description, ii. 676.
Exoascus Alni-incane, galls, ii. 523.
Exoascus amentorum. See E. Alni-incane.
Exoascus Carpini and Witches’ Brooms of
Hornbeam, ii. 527, 676.
Exoascus Cerasi, and Prunus, ii. 527.
Exoascus deformans, and ‘‘curl” disease, ii.
524, 676.
Exoascus epiphyllus, and Alnus incana, ii.
527.

t, i. 730.

of caryophyllaceous

Exoascus insititize on Prunus insititia, ii. 527.

Exoascus Pruni, and pocket-plum, ii. 524, 676.

Exoascus turgidus, and Betula verrucosa, ii.
527.

Exobasidex, hosts, ii. 688,

— hymenium, ii. 688.

Exobasidium, gall-formation, ii. 519,

Exobasidium Lauri, ii. 521, 688.

Exobasidium Rhododendri, ii. 688.

Exobasidium .Vaccinii, ii. 526, 688.

— — gall-formation, ii. 520.

Exocarpus, switch-plant, i. 330.

Exogamy, nature of, ii. 647.

Exogenz, of De Candolle, ii. 603.

Exosmosis. See Osmosis.

Exostemma longiflorum, flowers after pol-
lination, ii. 222.

Exothecium, of anther, ii. 94.

Experiments, cultural, difficulties of, ii. 513,

— questions addressed to nature, i. 18.

Explosive apparatus for pollen dispersal, ii.
260, 264, 265, 266, 267, 269.

Exposure, and opening of flowers, ii. 219.

Expulsive-fruits, range of, ii, 839,

Extinction, incomplete, ii. 902.

Extine, of pollen-grain, ii. 100.

Extrorse, of anthers, ii. 95.

Eyebright. See Euphrasia.

Eye-spot, of Chlamydomonas, function, ii.
629.

— of spermatozoid, ii. 52.

Eye-spots, of Volvox, ii. 635

INDEX.

“Byes”, leaf characteristics of shoots from,
ii, 516.

'— of potato, i. 651.

F,

Fading of corolla and pollination, ii. 286.

Fagus, i. 263; ii. 761.

— and galls of Hormomyia fagi, ii. 537.

— and Witches’ Broom, ii. 527.

_ of leaves from different localities, i.

— avoided by Mistletoe, i. 205,

— bud-scales, i. 626.

— cupule, ii. 434.

-— effect of grazing animals, i. 445,

— fertilization porogamic, ii. 413.

— host of Pilacre, ii. 687.

— hybrids of, ii. 583.

— mite-galls, ii. 529.

— phyllotaxis, i. 399.

— pollen-grains, ii. 99, 102.

— pollination, ii. 133, 135.

— protogynous, ii. 313.

— root-tip with mycelial mantle, i. 250.

Fagus sylvatica, cotyledons, i. 621.

— — deciduous hairs, i. 354,

— — dimensions, i. 722.

— — fohage constant, i. 559,

— — leaf-unfolding, i. 353.

— — liberation of cotyledons, i. 613.

—— normal and sucker leaves, ii. 515.

—— vernation, i. 350.

— — vertical range, i. 527.

Fairy rings, ii. 792.

Falearia ravini,
umbels, i. 530,

Fall of leaf, i. 347.

Falling Stars. See Nostoc.

False Indigo. See Amorpha.

Families, mutual relationships, ii. 605,

— of flowering plants, number, ii. 604.

Family, subdivision of alliance, ii. 617.

Fan-palms, spines, i. 433; ii. 740.

Fasciation, due to gall-mites, ii, 549,

Fascicle, i. 738.

Fascicled roots, i. 751.

Fat, in endosperm, ii. 421.

— transformation, i. 601.

Father-plant, in hybridization, ii. 557.

Fats, i. 216.

—vegetable, functions and composition,
i. 462.

Fatty acids, nature of, i. 463.

Favus, medical name for ringworm, i. 169.

Feather-foil. See Hottonia.

Feather-grass, See Stipa capillata.

Feather-grasses on a Russian Steppe, Pl.
VI.

Feather-leaved Palms, ii. 740.

Fegatella, receptacles, ii. 697.

“Fel de terra”, ¢.¢. earth-gall, native name
of Lophophytum mirabile tubers, i. 196.

Felspar, i. 80, 83.

— attacked by lichens, i. 257.

Felt, of hairs, i. 324.

— type of community, ii. 889, 894,

Felt-galls, ii. 528, 529.

Felt-hairs, and animals, i. 442.

Felt-like mycelial mantle on Phanerogam
roots, i. 249.

Fennel. See Faniculum.

Fenugreek, See Trigonella fenum-grecum.

Ferment action, hypothesis, i. 509,

—— of Bacteria, i. 162.

— of Pinguicula, action on milk, i. 142, 143.

— secreted by Drosera glands, i. 144,

Fermentation, alcoholic, i. 506,

— and enzymes, i. 464.

— and Moulds, i. 507.

—and respiration, mutual replacement, i.

» 509.

periodically pendulous

— and Saccharomyces, ii. 684.
— by Bacterja, i, 623.

— nature of, i. 505; ii. 519.
Ferment-fungi, i, 505.

947

Ferments, nature, function, &c., i. 464,
Fern, life-cycle, ii. 476,

— life-history, ii, 708.

— young sporophyte, ii. 472.

Fern-leaves, membranous scales, i. 355.
Fern-prothallium, i. 88, 384; ii. 67, 472, 708.
Terns, ii. 61.

— alternation of generations, ii. 472.

.— amphigonium, ii. 67.

— antheridia, ii. 67.

‘— apical cell, i. 579.

— as saprophytes, i. 100.

— buds on fronds, ii. 39.

— certain, which roll up their leaves, i. 314.
4 climate and distribution, ii. 457.
— effect of strong light, i. 391.

‘— fertilization, ii. 71, 475.

— fossil, i. 636.

— fronds and light, i. 413

— fruit, ii. 7.

+ habitats, ii. 705.

— hybrids among, ii. 582,

— not eaten by animals, i. 432,

— on, ground of woods, i. 109.

— on trees, i. 106.

— Paleozoic, ii. 612.

‘— propagation by offshoots, ii. 458.

— — historical review, ii. 8.

— rarely attacked by parasitic fungi, i. 168.
— rolling of young fronds, i. 348,

— saprophytic, on steep rocks, i. 108.

— scent, ii. 615.

—sori, ii. 11.

— spore formation, ii. 10.

— sporophyte, ii. 704.

‘— stem, varieties of, ii. 476.

— two generations distinct, ii. 474.
~\ various, ii, 107.

— wax on fronds, i. 292.

Ferraria, equitant leaves, i. 336.
Fertilization, ii. 415.

— and mucilage in Ferns, ii. 68.
— and order of blossoming, i. 739.
— and origin of species, ii. 594.

‘— and pendulous flowers, i. 530.

— changes initiated by, ii. 422.

— conditions in Phanerogams, ii. 72.

— essence of process, ii. 46.

— essential difference between Cryptogams
and Phanerogams, ii. 418.

— in Ferns, ii. 475.

— in Floridez, ii. 60.

— in Helianthemum marifolium, ii. 411.

—in Marsilia, Salvinia, and Selaginella, ii.
69.

— in Moulds, doubted, ii. 677.

— in Muscinew, ii. 65.

— in Peronospores, ii. 669.

— in Phanerogamia, ii. 717.

— of inclosed ooplast, ii. 54.

— of Orchids, by Darwin, ii. 738.

— resemblance in Muscinez and Characez,
ii. 66.

— twelve typical processes, ii. 48.

— unsolved problems, ii. 415.

Fertilizing-tube of Peronosporez, ii. 56.

— — of Saprolegniaces, ii. 484.

Ferula, flowering, i. 745.

‘Ferulago, geitonogamy, ii. 325.

Fescue-grasses. See Festuca.

Festuca, ii. 746.

— and Lolium, hybridization, ii. 583,

— leaf-closing, i. 340.

— pollination, ii. 142.

— stomata, i. 340.

‘— vascular bundles of leaf, i. 343.

Festuca alpestris and cattle, i. 436.

—— leaf, section, i. 342.

Festuca alpina, bulbils, ii. 454.

Festuca arundinacea, barbs, i. 439.

Festuca nigrescens, anthocyanin in glumes,
i, 522.

Festuca Porcii, leaf, section, i. 343.

Festuca punctoria, leaf, section, i. 345.

- — stomata on upper leaf-surface, localiza-

tion of wax, i. 292.
Festuca rupicaprina, bulbils, ii. 454.

948

Festuca vaginata, i. Pl. VI.
Festucas, poisonous, i. 341.
Fibres, fleshy, of seedling Orobanche, i, 185.
Fibrils, nuclear, i. 581.
Fibrin, i. 458.
Fibrous bark, i. 720.
— layer, of anther, ii. 96.
Ficacee, ii. 758.
Ficoidales, ii. 787.
Ficus, i. 193.
— buds on aérial roots, ii. 28.
— clasping roots, i. 702, 705.
— clinging roots, i. 754.
— flowers, ii. 159.
— formerly considered parasitic, i. 159.
— from chalk, ii. 613.
— gall-flowers, ii. 160.
— Indian species, climbing peculiarities, i.
709.
— inflorescence, receptacle and fruit-forma-
tion, ii. 435.
— insects and pollen, ii. 244.
— latex, i. 470.
— lattice-forming climbing roots, i. 711.
— number of species, ii, 162.
— pistil, ii. 160.
— pollen-grains, ii. 97, 102.
— protective stipules, i. 626.
—- relation to insects, ii. 159, 162.
— roots form living bridges, ii. 758, 760.
— synconium, ii. 159.
Ficus Benjamina, incrusting climbing roots,
i, 707.
Ficus carica and Blastophaga grossorum, ii.
161, 540.
— — gall-flowers, ii. 157.
— — inflorescences, ii. 157.
Ficus elastica, i. 755.
—— inflorescence, ii. 160.
—— roots, i. 756.
Ficus Indica, stem and roots, i. 755.
Ficus nitida, roots, i. 757.
Ficus pumila, flowers, ii. 157.
Ficus religiosa, roots, i. 757.
Ficus scandens, leaf-mosaic, i. 420.
— — unsymmetrical, unequal leaves, i. 422.
Ficus stipulata, climbing roots, i. 702.
— — foliage, i. 708.
Field-mice and plants, i. 763,
Field Pansy. See Viola arvensis, ?
Fig. See Ficus.
Figwort. See Scrophularia.
Filago, hairiness, i. 317.
Filago mixta and other hybrids, ii. 585.
Filament of ovule, i. 644.
— of stamen, i. 642; ii, 86, 88,
Filamentous cell-complex, i. 586.
il ts, protoplasmic, in Lath
cells, i. 136.
—— prey capturing, i. 135.
Filamentum, i.
Filices. See Ferns,
Filmy Ferns. See Hymenophyllacee.
Filtration of food-sap, from cell to cell, i. 270.
“Fingers and Toes”, cause of, ii, 522.
Fir-tree, wood perforated by sinkers of
Mistletoe, i. 209.
Fir-trees, curvature of branches, i. 416.
Firs. See Abies and Picea.
Firs and Birches, struggle for existence, ii.
514.
— vertical range, i. 527.
Fission-fungi. See Schizomycetes.
Fissured bark, i. 720,
Fistular leaf, i. 428.
Flagella of Chlamydomonas, ii. 629.
— of Dinofiagellata, ii. 625,
Flagellaria Indica, tendrils, i. 692.
Flamingo Plant. See Anthurium Scher-
zerianum,
Fleabane. See Inula.
Flecking, white, of leaves, cause of appear-
ance, i, 285.
Flies and Empusa Musee, i. 168; ii. 672.
—and finely-marked petals, ii. 131,
— and indoloid scents, ii. 207.
— and scroll-galls, ii. 530.

INDEX.

Flinty armour, i. 323.

Floatation of fruits, ii. 847.

Floating contrivances, i. 638.

Flora, application of term by Linnzus, i. 6.

— Arctic, general absence of hairs, i. 316.

— of north coast of Africa, spinose, i. 434.

— of Spain, spinose, i. 434,

— scope of term, ii. 1.

— why rich in rock-cracks, i. 109.

Flora der Provinz Brandenburg, Ascherson's
& Braun’s system, ii. 605.

Floral Biology, treatise by Loew, ii. 399.

Floral clock, Linnzeus’s, ii. 215.

Floral leaves, i. 597.

— — and fungal parasites, ii. 524.

— — arrangement, ii. 73.

— — division of labour, i. 645.

—— nature and succession, i. 640.

—— nectaries, ii. 176.

Floral receptacle, meaning, i. 736, 746.

— stem, adaptation to function, i, 749

—— nature and parts, i. 736.

Floras, ii. 885.

— migration of range, ii. 592.

— of Lapland, Sweden, England, Piedmont,
Carniola, Austria, &c., 18th century, i. 8.

— the chief, enumerated, ii. 898,

Florets, of Composite, protection of pollen,
ii. 116.

Florides, i. 161, 169, 246; ii. 606, 620.

— absence of wood and stomata, i. 284.

— alternation of generations, ii. 481.

— as epiphytes, i. 77.

— behaviour in distilled water, i. 78.

— favourite habitat, i. 105.

— fertilization and fruit-formation, i. 53, 61.

— fossil remains, ii. 614.

— fruit, ii. 7.

— habits, i. 587.

— luminosity, i. 388.

— pigment, i. 388.

— range, i. 390,

— seasonal development, i. 563,

— ‘‘sporangia” and spore-formation, ii, 22.

— structure, i. 590.

— tetraspores, ii. 24.

Flower, actinomorphic, ii. 229,

— application of term, i. 640.

— double, ii. 80.

— duties of, ii. 717.

— female, of Cupressus, ii. 443.

—— of Juniperus, ii. 442.

—— of Pinus Pumilio, ii. 722.

— largest in world, i. 202.

— lateral, i. 641.

— of Rafflesia Padma, i. 203.

— of Scybalium fungiforme, i. 189,

— protandrous, ii. 307.

— protogynous, ii. 307.

— size and autogamy, ii. 396.

— temperature variation, i. 502.

— terminal, i. 641.

— zygomorphic, ii. 229.

Flower-buds, respiratory heat, i. 498.

“ Flower-dust ”, ii, 85,

“Flower fidelity ” of insects, ii. 206.

Flower-opening, thermal constants, i. 559.

Flower-production and climatic conditions,
ii. 474,

Flower-stalk, in fruit formation, ii. 435.

—— origin, &c., i. 736.

—— tendrils, i. 693.

Flowering and elevation, i. 526.

— and sunshine, ii. 474,

— premature, caused by parasitic fungi, ii.
525.

— table of dates, i. 519.

Flowering Ash. See Fraxinus Ornus.

Flowering axes, protective waxy coatings, ii.
237.

Flowering Fern. See Osmunda regalis.

“Flowering Fungi”, applied to Phalloides,
ii. 691.

Flowering-rush. See Butomus.

Flowers, alpine, colour of, ii. 198,

— and animal visits, ii. 153.

— and insects, i. 743.

Flowers as insect shelters, ii. 163. .

— behaviour of perianth-leaves after fertili-
zation, ii. 222.

— cause of opening, ii. 219.

— change of colour, i. 376.

— classification according to sex, ii. 295.

— cleistogamic, ii. 391, 392.

— closing, ii. 215.

— colour, ii. 182.

— colour-contrasts, ii. 184, 189.

— cross-fertilization, ii. 300.

— double, and vegetative propagation, ii. 459.

—— long fresh, ii. 287,

— duration, ii. 214.

— ephemeral, ii. 212.

— gradations from hermaphrodite to uni-
sexual, ii. 295.

— heterostyled, ii. 302.

— honey secreting, ii. 171.

— imprisonment of insects, ii. 164.

— incompletely dichogamous, ii. 309.

— metamorphoses through gall-mites, ii. 548.

— mutual accommodation, i. 743.

— of Mosses, ii. 702.

— of Orobanche, i. 183.

— opening and closing, ii. 116, 212, 215.

— pendent, and insect visits, ii. 222.

— periodic bending, i. 531.

— — movements and protection of pollen, ii.

120.
— preservation through dryness, i. 262.
— protection against snails and slugs, ii.
238

— — by sticky glands, ii. 236.

— — from loss of heat, i. 529,

— seasonal colour-curves, ii. 197.

— size, ii. 185.

— —and temperature, ii. 503.

— structural correlation to insects, ii. 152.

— temperature within, i. 500.

Flowers of Tan. See Fuligo varians.

“Flowers of the Sea”, gas-vacuoles, i. 389;
ii. 621, 622.

Fluorescence, of chlorophyll solution, i. 372.

— of erythrophyll, i. 388.

Fluorescing pigments, of plants, i. 379.

Fluorine, in plants, i. 68.

Fluviales, general characters, ii. 738.

Fly-agaric. See Agaricus muscarius.

Fly-catcher. See Drosophyllum lusitanicum.

Fly-trap. See Dionea.

Feeniculum, foliage, i. 413.

— geitonogamy, ii. 325,

Feeni

um arc ticum.

P, ii. 427.

Féhn-wind, velocity, i. 525.

Folding, of grass-leaves, i. 341, 342, 343, 345.

— of Moss-leaves, i. 346.

Folia connata, i. 596.

— decurrentia, i. 596,

— perfoliata, i. 596.

— sessilia, i. 595.

Foliaceous carpels, ii. 83.

— Lichens, i. 245; ii. 694.

Foliage, sticky, ii. 236.

— variety, cause of, i. 396,

— wrinkled and grooved, i. 326.

— young, and frost, i. 545.

— — sensitiveness, i. 539.

Foliage-leaf, variety of functions, i. 627.

Foliage-leaves, i. 597.

—— position in relation to absorbent roots,
i. 92,

— — position relatively to horizon, i. 92.

—— transitions from water-catching to
animal-catching, i. 157.

Foliage-production, thermal constants, i.

Foliage-stem, i. 650, 655, 660, 710.

Foliar structures, ideas of origin, i. 8.
Folium=leaf=leaf-blade, i. 596.

Folium fulerang, i, 641.

Follicle, nature of, ii. 430.

Fontanesia, reserve-buds, ii. 33.
Fontanesia jasminoides, freezing, i. 546.
Fontinalis, aquatic Moss, ii. 704.

Food, conduction of, i. 269.

— selective absorption by Fungi, i. 166, 167.

Food-absorption, by coral-like and tuberous
caulomes, i, 114,
—— by Mildews, i. 166.
—— by water, marsh, &c., plants, i. 75,
— — general consideration of, i. 55.
— — movements related to, i. 56,
— — of Monotropa, i. 253.
— — osmosis in, i. 59.
——similarity of, in Moulds, Toad-stools,
and Discomycetes, i. 163,
—— theory of, i. 57.
Food-gases, transmission, i. 367.
Food-material, gaseous, i. 367.
—— ultimate destination, i. 371.
Food-salts, absorption by water-plants, i. 78.
—— absorption of, i. 67. %
——accumulation in uppermost layers of
earth, through action of plants, i, 259,
—— application of term, i. 66.
— — cause of movement, i. 72.
—— conduction, i. 513.
—— dilute solutions best, i. 73.
—— examples of selection by plants, i. 69,
—— in liquid of water-receptacles, i, 242.
—— raw, mechanics of movement, i. 269,
—— theory of absorption, i. 85.
— — transport, i. 366.
Foot, of Acetabularia, ii. 647.
— of Liverwort sporophyte, ii. 696.
— of young Fern sporophyte, ii. 475.
Force, due to growth and ice formation, i.
517.
— of growing cells, i. 513.
Forcing, of plants, i. 564.
Foreign pollen and stigma, ii. 404.
Forest flowers, characteristics, i. 655.
Forests, type of community, ii. 887, 892.
Forget-me-not. See Myosotis.
Fork-mosses, White leaved. See Leucobryum.
Form, in plants, on what it depends, i. 50.
Formic acid, i. 463.
——in Nepenthes pitcher, i. 135.
— —in stinging hairs, i. 441.
— — offensive weapon of ants, ii. 233.
Formic aldehyde, formation in assimilation,
i, 456.
Formica exsecta, protection of Serratula, ii.
242.
Forsythia viridissima, Japan, reserve-buds,
ii. 32,
Fossil Palms, ii. 742.
— plants, agents in preservation, ii. 612.
—— ancestors of modern plants, ii. 595
——and modern distribution, ii. 2.
— Mosses, occurrence, ii. 704.
— Myxomycetes, ii. 619.
— Vascular Cryptogams, cause of preserva-
tion, ii. 612.
Fossores and Asclepiads, ii. 258.
Foster, discoverer of Balanophora fungosa,
i. 190.
Foster-parent, selection of, by Orobanchew,
i, 185,
Foster-root, of Lophophytum, i. 194,
Foster-soil, on trees, i. 106.
Fourcroya, ii. 734.
— cohering pollen-grains, ii. 97.
Foxglove. See Digitalis.
— force of root-pressure in, i. 273.
Fox-tail Grass. See Alopecurus,
Fragaria, i. 708.
—nectary, ii. 174.
— persistent receptacle, ii. 435,
— procumbent, i. 661.
pull of roots, i. 767.
— runner, i. 664.
— specific scents, ii. 488.
Fragaria grandiflora, runner section, i. '735.
Fragaria vesca, fruit-ripening constant, i. 559.
— — vegetative propagation, ii. 801.
Fragillaria virescens, ii. 626.
Fragrzea obovata, lattice on palm-stem, i. 681.
— — supporting roots, structure, i. 761.
France, South-west, plants with evergreen
rolled leaves, i. 306.
Francisia eximia, leaf section, i. 279, 285.
Frengulins, of Braun, ii. 605.

INDEX,

Frankenia, habitat, extreme aridity of, 1. 237.
— salt on leaves and stem, i. 236.

Frankia Alni, gall on Alnus roots, ii. 521.
Fraxinella, See Dictamnus fraxinella.
Fraxinus, arrangement of foliage-leaves, i. 92,
— bark, i. 720,

— bud-scales, i. 626,

— flowering, ii. 150,

— leaf, grooved rachis, i, 232.

—— section, i. 232.

—— peltate group of cells, i. 232.

— pollarding, ii. 37.

— pollination, ii. 138,

Fraxinus excelsior, age, i. 722.

—-— and gall of Diplosis Cotularia, ii. 534.
— — dimensions, i. 722,

— — distribution of sexes, ii. 298,

—— &c., fasciation, ii. 549.

— — fruit and seed, ii. 428.

— — inflorescences and flowers, ii, 138,

— — protogynous, ii. 312.

Fraxinus nana, callus, ii. 30.

Fraxinus ornus, imperfect flowers, ii. 294,
—— scent, ii. 200,

Free cell-formation, nature of, i. 575,
Freezing of plants, i. 539.

—— modern views, i. 540.

— protection from, i. 546.

— theoretical considerations, i. 556,
Fritillaria and insect visits, ii, 222.

— autogamy, ii. 332,

— epiphyllous buds, ii. 43.

— nectaries, ii. 177.

— protection of pollen, ii. 118.

— waxy coating, ii. 237.

Fritillaria cirrbosa, &., tendrils, i, 692.
Fritillaria imperialis, ii. 731.
—— anther, ii. 90.

—— bulb scales, i. 624.
eee, hrodite and st:

e flowers,

ii. 297.

Fritillaria meleagris, duration of flowering,
ii, 213.

Frogbit. See Hydrocharis.

Frond, of Fern, characteristics, ii. 705.

—— morphological value, ii. 12,

— — functions, ii. 476.

Frondose, of Braun, ii. 605.

Frondose community, ii. 888, 893.

Frost, and leaf-fall, i. 359.

— and young foliage, i. 545.

Frozen, gardeners’ use of word, i. 356.

Fructification, of Fungi, colour, i. 165,

— of Loranthus Europzeus, i. 211.

Fruit, accessory structures, ii. 433,

— and seed of Conifera, ii. 441.

— boring, i. 618.

— botanical definition, ii. 47,

— broad sense, ii. 6, 427.

— green, i. 376.

— of Dudresnaya, ii. 50.

— of Erysiphee, ii. 60.

— of Ferns, ii. 68, 475.

— of Fucus, ii. 53.

— of Muscinee, ii. 66.

— of Penicillium, ii. 60.

— of Peronospores, ii. 56.

— of Vaucheria, ii. 58.

— ripening and allurement, ii. 446.

— types of, ii. 427.

Fruit-formation, essential conditions, ii. 70.

—— in Aspergillus and Penicillium, ii. 18.

—— in Eurotium, ii. 679.

Fruitful and unfruitful years, ii. 471.

Fruiting spike, of Arum maculatum, ii. 742.

Fruit-production, result of interference with,,
ii. 453.

Fruit-ripening of Characea, ii. 62.

— — of Equisetaces, ii. 68.

— — of Florides, ii. 62.

——of Marsilia, Salvinia, and Selaginella,

ii. 69.

— — of Muscinex, ii. 64.

— — thermal constants, i. 559.

Fruit-sugars, formation, i. 465.

Fruits, aggregate and collective, ii. 436.

Fruits and birds, i. 463.

949

Fruits and seeds of Conifer, ii. 442, 443.

— attachment to substratum, i. 615.

— boring of, i. 619.

— dry, subdivision, ii. 429.

— indehiscent, ii. 427.

— preservation through dryness, i. 262.

— protection from desiccation, ii. 449.

— size and weight, ii. 452.

— 80 called of Ascomycetes, ii. 20.

— with cupules, ii. 435.

— with modified receptacle or pedicel, ii.
436.

— with persistent receptacles, ii. 434.

Frullania, pitchers on leaves, i. 255.

Frullania dilatata, ii. 698.

—— mode of adhering to bark, i. 106.

Frustule, of Diatoms, ii. 625.

Frutex, i. 715.

Fruticose Lichens, ii. 694,

Fruticulus, i. 715.

Fucacez, as host plants, i. 77.

— characteristics, ii. 663.

— reproductive protoplasts, ii. 50.

Fuchs (1501-1566), i. 4.

Fuchsia, flowers after pollination, ii. 286.

— viscin of pollen-grains, ii. 101.

Fuchsia coccinea, &c., scarlet flower, ii. 196.

Fucoidea, i. 169; ii. 606.

— size compared to attachment, i. 78.

Fucus, fruit, ii. 53.

— no alternation of generations, ii. 481.

— oosphere and spermatozoids, i. 29.

— structure, i. 590; ii. 51, 664.

Fucus vesiculosus, fertilization, ii. 52.

Fuligo varians, colour of, i. 32.

Fuller's Thistle. See Cirsium.

Fumaria, behaviour to own and foreign
pollen, ii. 407.

Fumaria claviculata, branch-tendrils, i. 694.

— drupaceous nut, ii. 427, 429.

— honey concealment, ii. 180.

— leaf-stalk tendrils, i. 692.

Fumaria officinalis, cotyledons, i. 621.

—— flower, diadelphia, ii. 293.

Funaria, hybrids, ii. 582.

— spermatozoid, i. 29.

Funaria hygrometrica, chlorophyll-granules,
change of shape, i. 381.

Function, double, of various plant mechan-
isms, i. 308.

Fundamentum. See Hypocotyl.

Fungal hyphe, modes of growth, i. 589.

Fungi, i. 161; ii. 617, 620.

— advantage of luminosity, i. 504,

— as disintegrating agents, i. 99, 263.

—at home, ii. Pl. XIV.

— characteristics, ii, 668,

— division of Thallophyta, ii. 604.

— effect on cells attacked, ii. 518.

— ferment, i. 505.

— fleshy, loss of bulk through loss of water,
i, 216,

— fossil remains, ii. 614.

— hyphe in bark, i. 106.

— of Lichen community, i. 244.

— on ground of woods, i. 109.

— parasitic, alteration of form by, ii. 518.

— — cause of skin-diseases, i. 168.

—— extent of attack, i. 164.

— — hyphe of, i. 165.

—— numbers on one host, localized attack,

&e., i. 168.

— peat, unsuitable soil for, i. 102.

— plasmoid, feeding of, i. 56.

— rapid development of fructification, i. 117.

— reason of abundance in woods, i. 252.

— respiratory heat, i. 497.

— saprophytic, i. 99.

— specific scents, ii. 488.

— variety of appearance, i. 110.

Fungus-flies, i. 504.

Fungus-galls, ii, 521.

Fungus melitensis, apothecaries’ name for
Cynomorium coccineum, i. 198.

Fungus- mycelium, importance to roots of
plants, i. 250.

Funiculus, of ovule, i. 644; ii. 81.

950

Funkia, cross-fertilization, ii. 304.

— grooved leaf-stalk, i. 95.

— insects and pollen, ii. 245,

— pollen deposition, ii. 277.

— polyembryony, ii. 469.

— stamens as insect platform, ii. 225.

— venation, i, 633, 634.

Funkia ovata and other species, seed dis-
persal, ii. 449.

Furfuraceous, texture, i. 324.

Furze. See Ulex.

G.

Gagea, colour of flower, ii. 183.

— dispersal of bulbils, ii. 810.

— epiphyllous buds, ii. 43.

Gagea Bohemica, bulbils, ii. 462.

Gagea lutea, ii. 729.

—— dehiscence of pollen-sacs, ii. 93.

—— flower, hexandria, ii. 289.

— — habitat, i. 654.

— — hermaphrodite, ii. 296.

—— protection of bulbs, i. 551.

~—— weather and autogamy, ii. 391.

Gagea Persica, plant and bud-like offshoots,
ii. 460.

Galactodendron utile, Venezuela, latex, i.
470.

Galanthus, autogamy, ii. 333.

— double flowers, ii. 80.

— germination, i. 604.

— habitat, i. 654.

— pollen, ii. 85, 99, 118, 274.

Galanthus nivalis, ii. 734.

— — and loss of heat, i. 529.

—— duration of flower, ii. 214.

— — flower, ii. 176, 729.

—— nectaries, ii. 176.

—— stamen, ii. 91.

— — winter rest of bulb, i. 562.

Galega, and insect visits, ii. 223.

Galeobdolon luteum, cause of flecked ap- |
pearance of leaves, i. 285.

Galeopsis, roots, i. 772.

— transference of pollen, ii, 252,

— variability of floral colour, ii. 569.

Galeopsis angustifolia, pollen and insects, ii.

129, i

— — stamen, ii. 91.

Galeopsis grandiflora, flower, ii. 226.
Galeopsis ochroleuca, autogamy, ii. 356.
Galeopsis pubescens, cotyledons, i. 621.
Galeopsis tetrahit, autogamy, ii. 356.
—— insect platform, ii. 227.

INDEX.

| Gall-mites, ii. 527.
|, — — and doubling of flowers, ii. 548.

—— and fasciation, ii. 549.

Fees? cluster-galls on Thymus Serpyllum, ii.
547.

| _ — position of galls, fi. 529.

Gall-producing insects, ii. 527.
Gall-structures and origin of species, ii. 550.
— — cause and characteristics, ii, 519.

— — known number, ii, 549.

| Gall-wasps, ii. 527.

Gallesio, statements about Bizzaria, ii. 569.
Gallic acid, from tannin, i. 507.

| Galls, animal, ii. 533, 534.

— — classification according to form, &c., ii.
526, 528,

—— escape of larva, ii. 538.

— — fruit-like forms, ii. 552.

— formation, i. 255. 5

— of Gymnosporangia, ii. 520.

— origin, puzzling features of, ii. 550.

— parasitic nature, i. 255.

— solid, places of origin, ii. 540.

— — protective structures, ii. 526.

—— structure, &c., ii. 535.

— transmission of effects, ii. 553.

— various, ti. 523.

Gametangia, of Acetabularia, ii. 647.

— of Botrydium, ii. 642.

— of Conjugate, ii. 654.

Gamete, eye-spots, ii. 629.

Gametes, of Botrydium, ii. 642.

— of Chlorophyces, ii. 628.

— of Hydrodictyon, ii. 641.

— of Ulothrix, ii. 50, 648.

— of Vaucheria, ii. 643.

Gamopetalw, of Bentham and Hooker, ii.
604.

— of Endlicher, ii. 604.

Gamophycez, ii. 617.

— description, ii. 627.

Garcinia, dehiscence of pollen-sacs, ii. 93.
— stamen, ii. 91.

Gardeners and “‘ennobling”, ii. 554.
Gardeners’ fables, ii. 556.

| Gardenia, scent, ii. 203.

Gardens, Vienna and Blaser, experimental
culture in, ii. 407, 508.

Garlic, Broad-leaved. See Allium ursinum.

— seeds and heat, i. 555.

Garlics, scent of flowers and foliage-leaves,
ii, 199.

— specific scents, ii. 488.

‘| Gases, nutrient, i. 60.
‘| Gasterolichenes, one known form, ii. 695.

Gasteromycetes, as Lichen-fungl, ii. 693,
— capillitium, ii. 22.

Galinsoga parvifiora, size of infl ii.
186.

Galium, hybrids, ii. 585.

— stipules, i, 637.

Galium Aparine, ii. 537.

—— hooked fruit, ii. 871.

—-— prickles, i. 677.

Galium Austriacum and cuckoo-galls, ii. 544.

Galium boreale, &c., galls on, ii. 544, 545.

Galium Cruciata, flowers, sexual conditions,
ii. 296.

—— scent, ii. 202,

Galium infestum, duration of flowering, ii.

Galium mollugo, weaving habit, i. 674.

Galium retrorsum, dispersed by animals, ii.
874.

Galium uliginosum, prickles, i. 677.

Galium verum, scent, ii, 202.

Gall, compound, ii. 528, 542.

— derivation of word, ii. 528.

— of Nematus pedunculi, section, fi. 531.

— simple, ii. 528.

— solid, on root, ii. 541.

Gall-apple, use of term, ii. 528,

Gall-flowers, nature of, ii. 295.

— — of Ficus, ii. 160.

Gall-gnats, ii. 527.

Gall-like deformations caused by Exoas-
caces, ii. 676. :

, ii. 689.

— dispersal of spores, ii. 826.

— resemblance of Balanophores to, i. 190.
— respiratory heat, i. 498.
— spore-formation, ii: 22.

-| — various, ii. 690.

Gastri th

juice, tion of Ni
compared to, i. 135.

pitcher.

‘) Gaura, viscin of pollen-grains, ii. 101.

Gean. See Prunus Avium.
Geaster, appearance of, i. 112,
Geaster fornicatus, ii. 690.
Geaster multifidus, ii. 690.

Genera Plantarum of Bentham and Hooker,
ii, 604, 617.

— — of Endlicher, ii. 604.

Generation, sexual, of Ferns, ii. 67.

— spontaneous, of simplest forms, ii. 607.

Generations, advantage of alternation of, ii.

Generations, alternation of, ii. 7.

— — in zoophytes, ii. 470.

— of plants, succession and crowding out, i.
268.

— sexual and asexual relations, ii. 474.

Generative cell, of pollen-grain, ii. 420.

Genetic spiral, i. 398.

Genetyllis tulipifera, coloured bracts, ii. 183.

—— sheltering of pollen, ii, 108.

Genista, i. 330, 376.

— explosive flowers, ii. 267.

— mycorhiza, i. 251.

— protection of stomata from wetting, i. 298.

Genista Anglica, &c., spinose, i. 443, 445.

Genista pilosa, geographical distribution, i.

298,

—— peculiar feature, i. 298.

—— procumbent stem, i. 661.

—— protection of stomata from moisture, i.
298.

Genista tinctoria, and galls of Cecidomyia
genisticola, ii. 546.

— — phyllotaxis, i. 408.

Genlisea, geographical distribution, i. 124.

—utricle, structural details, i. 124. -

Gentian, Dwarf. See Gentiana acaulis.

Gentiana, autogamy, ii. 372, 387.

— — in stemless forms, ii. 386, 396.

— cross-fertilization, ii. 301, 304.

— guides to honey, ii. 248.

— hybridization in, ii. 585.

— introrse anthers, ii. 95.

— long-stalked, and hybridization, ii. 585.

— nectaries, ii. 175, 178.

— odourless, i. 209, 431.

— opening and exposure, ii. 219.

— opening of flower, ii. 212, 220.

— pollen deposition, ii. 277.

— protection of pollen, ii. 113.

— stigma, ii. 282.

— storing of pollen on style, ii. 359.

Gentiana acaulis, i. 228.

—— abode for beetles, ii. 163.

— — blue flower, ii. 198.

— — favourite soil, ii. 496.

—~gall-mites and flower metamorphosis,

ii, 548.

—— section of leaf-base, i. 232.

— — temperature within flower, i. 500.

—— water-collecting grooves of leaves, i.
231.

Gentiana angustifolia, ii. 387.

Gentiana asclepiadea, i. 451.

—~— autogamy, ii. 372.

— — insect reception, ii. 229.

— — opening of flowers, ii. 219.

—— protandrous, ii. 311.

— — twisting of internodes, i. 417.

Gentiana Austriaca, suction cells of roots, i.

115.

Gentiana Bavarica, flower, ii. 181.
— — habitat, i. 113.

— — honey concealment, ii. 182.
and exposure, ii. 219.

Geitonogamy, in Eupatorium, d
320.

— in hybrids, ii. 583.

— in Umbellifera, ii. 323.

— nature of, ii. 301, 317 et seq.

— with adherent pollen, ii. 320.

— with dust-like pollen, ii. 329.

Gelatinous Lichens, i. 244, 694.

Gelidium, where thrives best, i. 105.

Gemma, i. 596.

Gemme. See also Thallidia.

— of Mosses, ii. 702.

— of Mucor, ii. 673,

Gemmation, i. 573, 575.

Genera, of flowering plants, number, ii. 604.

Genera Plantarum, of A. L. de Jussieu, ii.
602.

—— protogynous, ii. 311.

— — scentless, ii. 209,

— — stigma, ii. 282.

Gentiana campestris, corolla and autogamy,

ii. 366,

—— weather and autogamy, ii. 391.

Gentiana Charpentieri, hybrid of G. lutea x
G. punctata, ii. 586.

Gentiana, ciliata, abode for beetles, ii. 163.

— — anther, ii. 90.

.| —— distribution of sexes, ii, 300.

—— pollen-grain, ii. 100.

—— protandrous, ii. 311.

—— scent, ii, 201.

—— suction cells of roots, i. 115.

:| Gentiana Clusiana, pull of roots, i. 768.

Gentiana Clusii, favourite soil, ii. 496.

— — flowers and autogamy, ii. 388.
Gentiana cruciata, protandrous, ii, 311.
Gentiana germanica, grooving of stem, i. 95.
— — heterostyly, ii. 302.

— — protogynous, ii, 311.

— — suction cells of roots, i. 115.

Gentiana glacialis, corolla and autogamy, ii. |

— — guides to honey, ii. 248.
— — habitat, i. 112.
— — protogynous, ii, 311,
— — weather and autogamy, fi. 391.
Gentiana lutea, and field-mice, i. 763,
— — and hybridization, ii. 585.
Gentiana nana, anther, ii. 90.
— — habitat, i. 112.
— — shortest stem, i. 660.
Gentiana nivalis, cross-fertilization, ii. 301.
— — opening and closing, ii. 116, 220,
Gentiana Pannonica, and field-mice, i, 763.
— — insect reception, ii. 229.
— — protandrous, ii. 311. i
Gentiana Pneumonauthe, abode for beetles, ;
ii. 163.
—— insect reception, ii. 229.
—— protandrous, ii. 311.
Gentiana prostrata, habitat, i. 112.
— — protandrous, ii. 311.
—— weather and autogamy, ii. 391.
Gentiana punctata, and field-mice, i. 763.
—— insect reception, ii. 229.
—— protandrous, ii. 311.
Gentiana purpurea and hybridization, ii. 585.
Gentiana Rhetica, gall-mites and flower-
metamorphosis, ii. 548.
— — grooving of stem, i. 95.
—— heterostyly, ii. 302.
— — opening of flowers, ii. 219.
—— pollen-grains, ii. 98.
— — protogynous, ii, 311.
—— suction cells of roots, i. 115.
Gentiana verna, blue flower, ii. 198.
—— effect of mutilation, ii. 517.
— — protogynous, ii. 311,
—— scentless, ii. 209.
Gentianacex, ii. 771.
— autogamy in, ii. 366.
— dichogamy in, ii. 311.
— grooving of stem, i. 95.
— heterostylism in, ii. 302.
— hybrids among, ii. 585.
Gentianex, Ashes, &c., habitat in relation to
water-collecting habit, i. 240.
— water-collecting arrangement of leaves, i. |
156, 231.
Geoglossum, i. 112; ii. 683.
Geographical areas, enumerated, ii. 898.
— position and blossoming, i. 565.
Geometrical arrangement, of cells and leaves, '
i. 405.
Geotropism, positive, i. 88.
—— neutralized in roots of certain plants, .
i. 90.
Geraniacex, autogamy in, ii. 335.
— nectaries, ii. 176. '
Geranium, alternative cross- and self-polli- |
nation, ii. 336.
— venation, i. 632.
Geranium argenteum, cross-fertilization, ii. |
306.

—— &e., dichogamy, ii. 311.

Geranium columbinum, &c., autogamy, ii. 336.

—— &c., protogynous, ii. 311.

Geranium divaricatum, weaving habit, i. 674,

Geranium lucidum, autogamy, ii. 336.

—— sexual conditions, ii. 296.

Geranium nodosum, weaving habit, i. 674.

Geranium palustre, seed-dispersal, ii. 835.

— — weaving undershrub, i. 673.

Geranium pratense, cross-fertilization, ii. 306.

— — duration of flowering, ii. 213.

Geranium pusillum, autogamy, ii. 332.

Geranium Pyrenaicum, leaf-mosaic, i. 410.

Geranium Robertianum, guides to honey, ii.
249.

— — pollen-grains, ii. 97.

| — cotyledons, i, 622.

| — propagation by leaf-cuttings, ii. 41.

| Geum, hybrids, ii. 558, 585.
'| — mite-galls, ii. 529.

| Gilea tricolor, and frost, ii. 407.

| Ginger.

| Gingko biloba, i. 633; ii. 726.

| Glacial epoch, supposed cause, ii. 909.
| Glacier-fleas.

| Glaciers, seeds blown on to, ii. 861.

INDEX,

Geranium Robertianum, protection of pollen,
ii. 120.
Geranium sanguineum, scroll-gall, ii, 530.
sible sylvaticum, cross-fertilization, ii.
306.

— — effect of mutilation, ii. 517.

— — protandrous flowers, ii. 307.
Germander. See Teucrium.

Germen. See Ovary.

Germinal vesicle. See Ooplast.
Germination, Githago, &e., i. 610.

— modes of, i. 602 et seq.

— of pollen-grain, ii. 407.

— thermal constants, correction, i. 558, 561.

| Gesneraces, ii. 575, 771.

— buds on leaf-cuttings, ii. 43.

— nectaries, ii, 174,

— propagation of hybrids, ii. 556.
— scarlet flowers in, ii. 196.

Geum coccineum, autogamy, ii. 381.
Geum macrophyllum, mite-galls, ii. 529.
Geum montanum, &c., autogamy, ii. 381.
— — — distribution of sexes, ii. 298.
—— — flowers, sexual conditions, ii. 303.
—— plumed achenes, ii. 858.

Geum reptans, runner, i. 664.

Geum rivale, autogawy, ii. 390.

| —— protection of pollen, ii. 118,

Geum urbanum, elevation and coloration,
ii. 511.

—— hooked style, ii. 873.

— — undershrub, i. 715.

Giant Puff-ball. See Lycoperdon giganteum.

Gilea, corolla and autogamy, ii. 367.

— seed mucilage, i. 615.

Gills, of Agaricinez, ii. 689.

See Zingiber.

Gingko, compared to oviparous animal, ii. 450.
— dicecious, ii. 299.

—-—at Vienna, female graft on male tree, :
ii, 572. :

—— branch and young fruit, ii. 443.

— — defoliation rapid, i. 361.

—— embryo detachment, ii. 480.

—— flowering at Kew, ii. 474.

— — seed-coat, ii. 439.

— — seeds, ii. 440.

—— venation, i. 635.

Girder, form of mechanical tissue, i. 727, 728. ,

Girders, fused into tubes, i. 730. :

— secondary, i. 731. :

See Poduras.
Glacier Pink. See Dianthus glacialis,

Gladiolus, ii. 734.
— bees and pollen, ii. 247.

| — eross-fertilization, ii. 304.
| — equitant leaves, i. 336.

— nectary, ii. 176.

—nectary concealment, ii. 181.

— pollen deposition, ii. 278.

— propagation, ii. 556.

— ternary hybridization, ii. 560.

Gladiolus segetum, hermaphrodite and pis-.
tillate flowers, ii. 297.

— — stigma, ii. 279, 282.

Gland, of Drosera, i. 144, 145.

— of Sarracenia pitcher, i. 126, 150.

Gland-cells, in Nepenthes, i. 135.

— — of Drosera, behaviour when stimulated,
i. 147. i

Gland-like organs, water imbibing, i156. |

Glands, and fruit protection, ii. 447.

— behaviour in Pinguicula vulgaris, i. 141.

— in leaf of Dionzea, i. 149.

— of Aldrovandia, i. 150, 153.

— of Drosophyllum leaf, i. 154,

— protective secretory, ii. 234. |

— secretory, gradations in differentiation, i. |

157.

951

Glands, stalked, of Bartsia, i. 139.

— viscid, double function of, i. 156.

— water-absorbing, of Alpine Roses, i. 232.
Glandular hairs, classificatory value, ii. 564.
Glauber’s salts, i. 50.

| Glaucium, flower shape, ii. 167.

Glaucium corniculatum, &c., recurrent open-
ing, ii. 213.
Glaucium luteum, cross-fertilization, ii. 301.

'| — — protogynous, ii. 310.
'| Glaux, morphology of flower, ii. 71.

Glaux maritima, ovary, ii. 76, 79.

| Gleba, of Gasteromycetes, ii. 689.

Glechoma, distribution of sexes, ii. 298.

Glechoma hederacea, runner, i. 664.

Gleditschia, and Acer, struggle for existence,
ii, 515.

— reserve-buds, ii. 31.

| — spines, i. 433.

Gleditschia Sinensis, scent, ii. 202.

| Gleditschia triacanthos, scent, ii. 202, 209.
| Gleditschias, American, leaf, diurnal posi-

tions, i. 534.
— leaf movements, i. 338.
Gleichenia, ii. 707, 708.
— buds on frond, ii. 39.
Gleichenia alpina, sporc
Globba, ii. 736.

pinna, ii. 11.

'| Globe-animatlcule, oldname for Volvoxz,which

see.

Globe-flower. See Trollius.

Globoid, i. 457.

Globularia, dehiscence of pollen-sacs, ii. 89,

92, 124.

— protogynous, ii. 312.

Globularia cordifolia, procumbent stem, i.
661, 662. ;

——stamen, ii. 91.

Globulariacez, ii. 771.

.| Glosocapsa, appearance and occurrence, ii.
621

— habit, i. 587.
Glosocapsa sanguinea, reproduction, Pl. L,, i.
575.

| Gloiotrichia echinulata, ii. 622.

Gloriosa superba, tendrils, i. 692.

‘| Glow-worm, luminosity, i. 386.

Gloxinia, bees and pollen, ii. 247.
— velvety appearance, i. 320.

| Glucose, from tannin, i. 507.

Glucosides, conducting tissues for, i. 479.
— decomposition, i. 463, 465.

— function, i. 462.

— poisonous, of unripe fruit, ii. 446.
Glume, flowering, ii. 746.

Glumes, anthocyanin in, i. 522.

‘| Glumiflore, characteristics, ii. 745.
‘| Glutamin, i. 464,

Glutin, composition, i. 458.

‘| Glyceria, orientation of unfolding leaves, i.

350.

| Glyceria aquatica, &c., and Ustilago, ii. 675.

Glyceria fluitans, habit and habitat, ii. 502.

Glyceria spectabilis, protection of stomata
from moisture, i. 294, 295.

Glyceride, of a fatty acid, in cuticle, i. 309.

Glycérine, production, i. 507.

Glycine Chinensis, scent, ii. 202.

—— supports at Miramare, i. 680.

Glycocoll, absorption of, i. 104.

Glycyrrhiza, leaf, diurnal positions, i. 534.

‘| Glycyrrhiza echinata, fruit protection, ii. 442.

Glycyrrhiza glabra, tubercles on root-fibres,
ii. 521.
Gnaphalium, i. 489.
Gnaphalium alpinum, distribution of sexes,
ii, 299.
—— &., parthenogenesis, ii. 465.
— — parthenogenetic fruit, ii. 84.

|| Gnaphalium carpaticum, ii. 465.

—- distribution of sexes, ii. 299.

| Gnaphalium dioicum, ii. 465.
| —— distribution of sexes, ii. 299.
| Gnaphalium Leontopodium, i. 315.

— — coloured bracts, ii. 183.
—— dichogamy, ii. 312.
— — distribution of sexes, ii. 297.

952

Gnaphalium Leontopodium, hairiness and
habitat, i. 316.

— — hairs, i. 321.

Gnaphalium luteo-album, gall of Entyloma
Aschersonii, &c., ii. 521.

Gnaphalium tomentosum, hairs, ii. 330, 321.

Gnetacez, description, ii. 726.

— embryo development, ii. 437.

— Endlicher’s grouping, ii. 604.

— seed-coats of, ii. 441.

Godetia, viscin of pollen-grains, ii. 101.

Goebel, classification of Thallophytes, ii. 606.

Goethe, i. 6.

— attitude towards Linnean system, ii. 287.

— his typical plant, i. 12.

— on seed-dispersal, ii. 833,

— treatise on metamorphosis, i. 10.

Gold Ferns. See Gymnogramme.

Gold of Pleasure. See Camelina sativa,

Golden Rod. See Solidago.

Golden Saxifrage. See Chrysosplentum.

Gomontia polyrhiza, life-cycle, ii. 651.

Gomphonema capitatum, ii. 626.

— colonies, i. 585.

Gonatonema, aplanospore formation, ii. 658.

Goneoclinic hybrids, ii. 559, 587.

Gongora galatea, twisting of ovary, ii. 224.

Gonidia, of Lichens, ii. 692.

Goniolimon, absorptive organs, i. 234.

Gouium, structure, &., ii. 631.

Goodeniacew, ii. 767.

Goodyera repens, habitat and foliage, i. 110,

Gooseberry. See Ribes Grossularia.

Gorteria ringens, colour-contrast in flower,
ii. 190.

Gossypium Barbadense, hairy seeds, ii. 855.

Gossypium herbaceum, fruit and seeds, ii.
423.

Gourd. See Cucurbita Pepo.

Graft, relation to stock, ii. 571.

Graft-hybrids, ii. 569, 572.

Grafting, i. 213, 214.

Grafting, perpetuation of hybrids by, ii. 556

— resemblance to parasitism in Loranthaces,
i. 213.

Graminez, ii. 719.

— attacked by Smut-fungi, ii. 674.

— brood-bodies, ii. 29,

— caryopsis, ii. 746.

— cleistogamy in, ii. 392.

— course of pollen-tubes, ii. 408.

— dehiscence of pollen-sacs, ii. 93.

— descriptive details, ii. 745, 746.

— dichogamy, ii. 140, 312.

— elevation and coloration, ii. 511.

— embryo of, ii. 422.

— from chalk, ii. 613.

— germination, i. 604.

— glumes, ii. 434.

— hybrids among, ii. 583,

— pollen-grains, ii. 99.

— pollination, ii. 133, 140, 141.

— substratum, ii. 498.

— venation, i. 634.

Grammatocarpus volubilis, nutation, i. 683,

G jtophora serpentina, ii. 626.

Grammitidez, tribe of Polypodiaces, ii. 706.

Grammoptera, and Listera, ii. 256.

“Grandes espéces”, ii. 581.

Granite, i. 83.

Granulose, formation, i. 459, 460.

Grapes, and Peronospora viticolo, ii. 670.

Grape-sugar, decomposition by yeast, i. 506,

Graphite, origin of, ii, 610.

Grasses. See also Graminec.

— anthocyanin and elevation, i. 522,

— aqueous mantle of assimilating tissue, i.
369.

— localization of wax, i. 292.

— Mediterranean, hairiness of, i. 318.

—perennial, time of appearance in dry
regions, i. 318.

— periodic folding of leaves, i. 339,

—- reed-like, adaptation to wind. i. 427.

— silicic acid in, i. 67.

— stomata on leaves, i. 280.

— trabecule in green cells, i. 374.

INDEX.

Grass-leaves, folding of, i. 341, 342, 343.
Grass-tree, Australian. See Xanthorrhea
hastilis, Pl. XVI.
Grass Wrack. See Zostera.
Gravitation, force to be overcome in ascent
of crude sap, i. 269.
Grayness, of shore vegetation, i. 390.
Grazing animals and young trees, i. 445,
Greek flora, general grayness of, i. 317.
Green, intensity of, and illumination, i. 381.
—Algx. See Chlorophycee.
— — zone in sea, i. 390.
Greenland, winter temperatures, i. 547.
Green Laver. See Ulva latissima.
Green-rot, of trees, i. 263.
Green tissue, production of, i. 426.
—tissues, behaviour towards light, i. 383,
384.
Gregoria, heterostyly, ii. 302.
Grevillea, vertical leaf-blades, i. 336.
Grew, Nehemiah, figures of plant anatomy,
i. 22.
—— on crumpled estivation, ii. 210.
Grimmia,. hybrids in, ii. 583.
— renders limestone friable, i. 258.
— vegetative propagation, ii. 458.
Grimmia apocarpa, absorption of carbonic
acid, i. 62.
Grimmia Hartmanni, parthenogenesis, ii. 464.
Grimmiz, collection of dust, i. 266.
— nutrition, i. 81.
— special absorptive cells of, i. 218.
— spore-dispersal, ii. 814.
Grindelia squarrosa, varnish-like covering,
i. 313.
Gromwell. See Lithospermum,
Grooves ou stem, and rain-water, i. 95.
Ground Ivy. See Glechoma hederacea.
Groundsel. See Senecio vulgaris.
Ground water, inefficiency, &c., ii. 501.
Growth and heat, i. 512, 518, 557.
— and light, i, 518,
— and periodic movements, ii. 220.
— and snow-pressure, i. 523.
— dependence on water, i. 510.
— geometrically considered, i. 405,
— hypothetical mechanism, i. 512.
— influence of elevation on, ii. 407, 508, 509,
523.
— nature of, i. 55.
—period of, in wettest season in certain
localities, i. 306.
Grubbiacess, ii. 754.
Gschnitzthal (Tyrol), i. 65.
— changes in flora of, ii. 910.
— Kerner’s experimental garden, ii. 453,
— mechanical force of roots, i. 514.
Guard-cells of stoma, i. 280.
—— — function and structure, i. 308.
Guelder-rose. See Viburnum Opulus,
Guepinia, appearance of, i. 112.
— shrivelling through loss of water, i. 216,
Guests of plants, bidden and unbidden, ii, 221.
Gulf Stream, blueness, i. 389.
Gulf-weed. See Sargassum bacciferum.
Gum-arabic, source, i. 458.
Gum-resin, water retention, i. 330.
Gum-tragacanth, source, i. 458.
Guttiferve of Braun, ii. 605,
Gymnadenia, ii. 737.
—and Noctue, ii. 256.
— hybrids, ii. 563, 583.
— pollen deposition and retention, ii. 284.
— spur and honey, ii. 255.
Gymnadenia Conopsea, and Nigritella nigra,
colour of flowers and hybrid, ii. 567.
— — capsules in dry and wet weather, ii. 448.
— — scent, ii. 201, 203.
—— seed, ii, 451,
Gymnoascus uncinatus, habitat, i. 118.
Gymnocladus, i, 488.
— bud-scales, i. 626.
Gymnocladus canadensis, leaf, diurnal posi-
tions, i.
— — reserve-buds, ii. 32.
— — separation-layers, i. 360.
Gymnogramme, sorus, ii. 706.

Gymnospermz, absence of fossil connecting
links with Phanerogams, ii. 613.

— classes, ii. 718. Y

— development of embryo, ii. 437.

— distinctive features, ii. 719,

— fertilization, ii. 418.

— fruits, ii, 437.

— homology of embryo-sac and contents to
germinated macrospore, ii. 478.

— of Endlicher, &., ii. 604.

— pollination, ii. 419.

— protection of ovule, ii. 72.

Gymnosporangi ] ores, &c., ii. 687.

Gymnosporangium clavarizeforme, &c., ii. 519,
521.

Gymnosporangium juniperinum,hetercecism,
ii. 686.

Gymnostomum, absence of peristome, ii. 703.

Gymnostomum curvirostre, lime incrusted,
i. 260.

Gynandre, floral characters, ii. 736.

Gynerium argenteum, pollination, ii. 142

Gypsophila, autogamy, ii. 345.

— nectaries, ii. 176.

Gypsophila paniculata, inflorescence, i. 738.

Gypsophila repens, anthocyanin, i. 522.

— — elevation and coloration, ii. 511.

Gypsum, good for clover, i. 74.

— in cell, i. 72.

— on leaves, i. 236.

Gyrocarpus Asiaticus, seed-dispersal, ii. 853.

Gyrogonites, fossil characeous fruits, ii. 661.

Gyrophoras, absorption of water, i. 218.

H.

Haastia, distribution and appearance, ii. 188.

Habenaria, ii. 737.

— pollen deposition and retention, ii. 284.

— specific differences and insect visits, ii.
256.

— spur and honey, ii. 255.

Habenaria bifolia, flower and pollination,

ii. 225, 227.

— — nocturnal perfume, ii. 208.

—— pollinia, ii. 256.

—— scent, ii. 201, 204.

Habenaria chlorantha, rostellum, ii. 255.

Habenaria Hookeri, specific distinction from
H. montana, ii. 256.

Habenaria montana, pollinia, ii. 256.

—— scentless, ii. 204.

Haberlea, nectary, ii. 175.

Haberlea rhodopensis, direction of flowers,
ii 225.

Habitat and greenness, i. 384. ‘

— and influence on plant form, ii. 497.

— and permanence of hybrids, ii. 587.

— and variation, i. 394.

— influence on anatomy, ii. 511.

— of epiphytes, i. 222, 325.

—of tamarisks, frankenias, &c., extreme
aridity of, i. 237,

Habitats, sorts of, ii. 879, 883.

Hacquetia, behaviour of stamens, i. 740.

— geitonogamy, details, ii. 323.

— protogynous, ii. 311.

Hadena and Habenaria bifolia, ii. 256.

Heematochrome, of eye-spot, ii 629.

Heematococcus, reason of name, ii. 631.

Hematococcus pluvialis. See Spherella.

Hairiness of plants, in relation to habit and
climate, i. 316.

Hair-mosses. See Polytrichum.

Hairs, absence of, in plants with incrusta-
tions, i. 313.

— actinia-like, i. 324,

— air-containing, protective functions, i. 314.

— articulated, i. 320.

— branched, i. 323.

— capitate or glandular, i. 229.

— cauline of Stellaria media, i. 229.

— clayey appearance due to, i. 324.

— covering, i. 321.

— dry, air-containing, chief means of protec-
tion from undue evaporation, i. 317.

Hairs, edible, of flowers, ii. 169,

— floccose, i. 324,

— glandular, absorption of ammonia, i, 65,

— — of Sarracenia, i. 126.

— multicellular, i. 320,

— of Aldrovandia leaf, i. 153.

— of leaves, in relation to water-absorption,
i, 227.

— on Erodium fruit, i. 620.

—on foliage, abundance in Mediterranean
district, &., i. 317.

— protection of chlorophyll, i. 392,

—— stomata from wetting, i. 292.

— protective secretory, ii. 234,

— protect young foliage-leaves, i. 353,

— scaly, i. 324,

— silicic acid in, i. 67.

— silicified, i. 440.

— soft felted, and grazing animals, i. 442.

— stellate, i. 322; ii. 564.

— stinging, mode of action, i. 439, 442,

— T-shaped, i. 321.

— tufted, i. 323,

— unicellular, i. 319,

— vesicular, i. 324,

— which retain moisture, i. 228.

Hairy covering and anthocyanin, i. 487.

Hakea, leaves of, ii. 751.

Hakea florida, Australia, protection of
stomata from moisture, i. 296,
——stomata, surface view and section, i.

297.
Halantium Kulpianum, stamen, ii. 87.
Hales, Stephen, work on vital phenomena of
plants, i. 16.
Halesia, propagation by root-slips, ii. 28,
Half-parasitic, i. 180.
Half-saprophytic, i. 180.
Halichondsia and Struvia delicatula, ii. 646.
Halictus, sheltering in flowers, ii. 163,
Halidrys, ii. 664.
Halimeda, relation to light, i. 388.
— thallus, ii. 645.
Hali coloured st
ii. 183.
— pollen and pollination, i. 645.
Halimocnemis gibbosa, stamen, ii. 87.
Halimocnemis mollissima, inflorescence, &.,
ii. 184.
Haller, Historia Plantarum, ii. 1.
Halophila, pollen and pollination, ii. 105.
— sub-aqueous pollination, ii. 739.
Halophytes, application of term, i. 74.
Haltica Atropx, beetle on Deadly Night-
shade, i. 431.
Haminia, stamen, ii. 87.
Hanburya mexicana, tendril, callus-like
growths of, i. 697.
Haplophyllum, honey protection, ii. 241.
Haplophyllum Biebersteinii, autogamy, ii.
337.

filaments,

Hard bast, i. 469, 474.

Hard Fern. See Blechnum Spicant.

Hare’sear. See Bupleurum.

Harpagophytum procumbens, hooked fruit
of, ii. 870.

Harpoon fruits, ii. 870.

Hart’s Tongue Fern.
vulgare.

Haustoria, and external stimulus, i. 771

— application of term in Fungi, i. 164,

— forms, origin, &&., i. 754.

— of Cuscuta, i. 174.

— of Erysiphes, ii. 59.

— of Mildews, ii. 677.

— of Mistletoe, death, i. 210.

— of parasites, i. 115.

— of Peronosporex, ii. 56,

Hawk-moth, ii. 153,

Hawk-moths, and flower-colour, ii. 196,

——and Honeysuckle scent, ii. 207. _

——and laterally directed flowers, ii. 225.

Hawkweed, Hairy. See Hieracium villoswm.

Hawthorn. See Crategus Owyacantha.

Hay-bacillus. See Bacillus subtilis.

Hazel. See Corylus.

Hearts’-ease, See Viola tricolor.

See Scolopendrium

INDEX,

Heat, action of, i. 58,

—and distribution of plants, i, 527,
— and dried seeds, i. 555,

— and growth, i. 512,

— and growth, estimation, i. 557,

— and opening of flowers, ii, 219.

— distribution in germination, i. 560,
— effect on growth, &c., ii, 503.

— effect on protoplasm, i. 553.

— evolution in respiration, i. 497,

— latent, i. 492.

— nature of, i. 58, 513.

— protection from loss, i, 528,

— sensible, i, 492.

— source of, i. 518,

— transformation by plant, i. 492,
Heath. See Erica.

Heath, Irish. See Dabeocia polifolia.
— vegetation, indigestibility, i. 432.
Hedera, colour and flies, ii. 197.

— easy vegetative propagation, i, 251,
— honey, ii. 173, 179.

— leaf-mosaic, i. 423.

— roots from leaf-stalks, i. 772.

— scent, i. 200.

yHedera Helix, climbing roots, i. 702, 705, 754.
—— embryo and cotyledons, i. 600,
—— erect stems as cuttings, i. 709.
— — flower-opening constant, i. 559.
— — grafting and dwarf trees, ii. 518,
—— on Oak, i. 703.

— + resistance to cold, ii, 489,

—-— scent, ii, 209.

—— variety in asexual shoots, fi. 471.
Hedera poetarum, and resistance to cold, ii.

Hedge-shrubs, mode of growth, i. 673.

Hedychium, ii. 736.

— hybrids and starch-grains, &c., ii. 566.

Hedychium angustifolium, ovary and fruit,
ii. 77.

Hedysarum Canadense, hooked fruit, ii. 871.

Heliamphora nutans, habitat, ascidia, &c.,
i. 124, 125.

Helianthemum, cleistogamy, ii. 393.

— conducting-tissue for pollen-tubes, ii. 410.

— duration of blossoms, ii. 214,

— elevation of leaf-stalks, i. 419.

— flowers follow the sun, ii. 123,

— hairs on, i. 317, 323.

—nectarless, ii. 167.

— pollen-grains, ii. 99.

— protection of pollen, ii. 127.

— stigma, ii. 281.

Helianthemum alpestre, protection of pollen,

ii. 120.

— — protogynous, ii. 310.

Helianthemum grandiflorum, erect and pro-
cumbent twigs, i. 417.

Helianthemum marifolium, fertilization, ii.
411.

Helianthemum Tuberaria, Mediterranean,
i. 319.

Helianthus, ovary, ii. 73, 78.

Helianthus annuus, germination constant,

i. 558,

—— movements of cotyledons, i. 532.

Helianthus tuberosus, alleged effect of graft
on Helianthus annuus, ii. 572.

Helichrysum, coloured bracts, ii. 187.

— decurrent leaves, i. 336.

— hairy covering in summer, i. 319.

— hermaphrodite and pistillate flowers, i. 297.

Helichrysum annuum, germination, i. 611,
613.

Helichrysum arenarium, &c., coloured bracts,
ii. 187.

— — flower-opening constant, i. 559.

— — with gall of Entyloma Aschersonii, ii.
621.

Helichrysum virgineum,Mount Athos, ii. 187.

Helicodiceros, pollination, ii. 164. :

Heliosperma quadrifiduin, seed-dispersal, ii.

852.
Heliotropium, scent, ii. 200.
Hell-bind, name for Cuscuta, i. 175,

Hellebore, White. See Veratrum album.

953

Helleborine. See Epipactis.

Helleborus, cross-fertilization, ii. 305.

— hybrids in, ii. 584.

— movements of stamens, ii. 250.

— nectaries, ii. 179.

— pollen deposition, ii. 278.

Helleborus niger, colour of sepals, ii. 183.

— — habit, ii. 773.

—-— nectaries, change of colour in floral

leaves, i. 376.

— — odourless, i. 431.

Helosis, leaf-scales, i. 191, 196.

Helotium Tuba, ii. 19.

Helvella, asci and ascospores, ii. 19.

Helvella fistulosa, &., i. 589; ii. 19, 83,
683.

Helwingia rusciflora, flowers on leaves, ii.
38

Hemerocallis, ii. 731.

— cross-fertilization, ii. 301.

— geographical distribution, ii. 402.

— latitude and opening, ii. 217,

— scentless, ii. 209,

— stigma, ii. 281.

Hemerocallis flava, duration of flowering, ii.
213.

— — roots, i. 760,
Hemerocallis fulva, latitude and closing, ii.
218,

— — opening and closing, ii. 212.

—— sterility under cultivation, ii. 402.

Hemibasidii, distinctive characters, ii. 676.

Hewionitis, sori, ii. 706.

Hemitelia, indusium, ii. 708.

Hemlock. See Conium maculatum.

Hemlock Firs, ii. 725.

Hemp. See Cannabis sativa.

Henbane. See Hyoscyamus.

Henbit Dead-nettle. See Lamium amplexi-
caule.

Henslowia, parasitic, i. 204.

Hepatica triloba, anthocyanin, i. 520.

—— cause of flecked appearance of leaves,

i. 285,

— — dates of flowering, i. 519.

—— duration of flowering, ii. 213,

— — flower colour and habitat, if. 194.

—— winter protection, i. 550.

Hepatic, absorption cells of, i. 86.

— absorption of carbonic acid, i. 62,

— absorption of water, i. 218.

— afford home to Podifersz, i. 225.

— and Nostoe, ii. 622,

— apical-cell, i. 578.

— cell-complexes, i. 591.

— description, ii, 696.

— forming rings, ii. 794.

— in cascades, i. 79.

— offshoots dispersed by rain, ii. 809.

—on mouldered dust of dead trees, i. 109.

— origin of sporophyte, ii. 654.

— pressure exerted by rhizoids, i. 514,

— saprophytic, on steep rocks, i, 108.

— structure, i. 590.

Heracleum, habitat and greenness, i. 384.

— peripheral flowers, ii. 186.

— water-receptacles, i. 240.

Hi eum palmat organic r
inflated vagina, i. 242.

Heracleum Sphondylium, flowering shoot, ii.

in

—— scent, ii. 202,
Herbaceous plants, effect of mutilation, ii.

— shoot, i. 656,

— stem, i. 715.

Herbe, i. 715.

Herbals, early, i. 4.

Herbarium, i. 5.

Herbivora, power of discrimination, ii. 488.

Herb Paris. See Paris quadrifolia.

Herbs, perennial, foliage-leaves and rain, i,
93.

Hercules-club. See Coryne pistillaris,

Hereditary modification, negative results of
experiments, ii. 514.

Hermannia, propagation by root-slips, ii. 28,

954

Hermaphrodite flowers, and wind fertiliza-
tion, ii. 134.

—— crossing in, ii. 301.

— — Linnean view, ii. 291.

Herminium, scent, ii. 202.

Herminium Monorchis, pollination, ii. 256.

Herniaria glabra, perennial, ii. 453.

Herpes tonsurans, due to Tricophyton ton-
surans, i. 169.

Hesperides, of Braun, ii. 605.

Hesperis matronalis, attraction of pollen-
tubes by foreign ovules, ii. 414.

— — opening of flower, ii. 212, 221.

—— scent, ii. 201, 209.

Hesperis tristis, night visitors, ii. 197.

—— opening of flower, ii. 212.

—— perfume, ii. 201, 208, 242.

Heterochromatism of flowers, ii. 569.

Hetercecism, of Uredinex, ii. 686.

Heterogamy, and autogamy, ii. 340, 390.

—various forms, and origin of species, ii.
595. :

Heteromorphism, application of term, ii.

Heterophyllous plants, i. 668.

Heteropogon, fruit, i. 620.

— moncecious, ii. 297.

Heterosporous Lycopodine, ii. 477.

Heterosporous Pteridophyta, ii. 704.

Heterospory, in Equisetales, ii. 711.

— of Hydropterides, ii. 709.

Heterostyled flowers, ii. 302, 396, 398, 405.

Hibernating shoots, of Potamogeton crispus,
i. 551.

Hibiscus, stigma, ii. 281.

Hibiscus ternatus, pollen-grains, ii. 99.

Hibiscus Trionum, autogamy, ii. 355.

—-— floral markings, ii. 190.

—— opening and closing, ii. 212.

— — vitality of spermatoplasm, ii. 96.

Hieracium, autogamy, ii. 372, 374.

— capitula closing and pollination, i. 741.

— geitonogamy, ii. 319.

— hybrids, ii. 585.

— indumenta of hybrids, ii. 564.

— leaves and light, i. 410.

Hieracium aurantiacum and H., pilosellz-
forme, hybrid, ii. 558.

Hieracium Auricula, stolons, ii. 663.

Hieracium gymnocephalum, Dalmatia, i.
319

Hieracium murorum, and bud-galls of
Aulax Hieracii, ii. 543.

Hieracium Pilosella, and gall of Psyllodes,

ii, 532.

—— anthocyanin in florets, ii. 220.

— — procumbent, i. 661.

— — protection of pollen, ii. 112, 114

— — rolling up of leaves, i. 314.

— — stolons, i. 663.

Hieracium staticefolium, flowers after
pollination, ii. 286.
Hieracium stoloniflorum, hybrid of H.

aurantiacum x H. pilosellaforme, ii. 586.

—— mean cross, ii, 558.

Hieracium sylvaticum, and bud-galls of
Aulax Hieracii, ii. 543.

Hieracium tenuifolium, anthocyanin, i. 520.

Hieracium tridentatum, and bud-galls of
Aulax Hieracii, ii. 543.

Hieracium umbellatum, autogamy, ii. 361.

Hieracium villosum, protection of stomata
by hairs, i. 292.

Hierochloa, hermaphrodite and staminate
flowers, ii. 297.

— scent, ii, 201.

Hierochloa australis, dichogamy, ii. 312.

High Alpine plants, autogamy in, ii. 399,

Higher plants not derived from lower, ii.
614.

Hilar caruncle, &c., ii. 425.

INDEX.

Himalayas, Edelweiss of, i. 316.

.— sun and: shade temperatures, i. 525,

Hi halia, thallus dif iation, ii. 664,

Himantoglossum and Orchis, hybridization,

i ii. 583.

. Hippocrepis, pollen expulsion, ii. 260.

Hippophae, dicecious, ii. 300.

| — hair-scales, i. 324.

|, — perianth and andrcecium, ii. 752.

:— pollen storing and dispersion, ii. 148, 150.

— radical shoots, ii. 27.

— weaving stem, i. 672.

| Hippophae rhamnoides, phyllotaxis, i. 400.

, — — protection of pollen from wet, ii. 109.

| — — spines, i. 443.

Hippuris, aérial and submerged leaves, ii.
505.

| — integument of ovule, ii. 81.
— stamens, ii. 86.
' Hips, of Roses, dispersal, ii. 444.
Historia naturalis, Pliny, ii. 1.
Historia plantarum, use of term, ii. 1.
Holcus, hermaphrodite and staminate
flowers, ii. 297.
— pollination, ii. 142.
Holly. See Ilex Aquifolium.
Holosericeus, texture, i. 320.
! Homochromatism of flowers, ii. 569.
| Homogyne, hermaphrodite and pistillate
flowers, ii. 297.
Homogyne alpina, geitonogamy, ii. 321.
Homogyne discolor, i. 303.
Homologies, danger of establishing, ii. 615.
Homosporous, ii. 478.
Homosporous Pteridophyta, ii. 704.
Honesty. See Lunaria.
Honey, alluring, i. 461.
— concealment, ii. 180, 181.
— guidance to, ii. 248.
— in Nepenthes pitchers, i. 134,
— secretion, ii. 172, 173.
Honey-bee, colour preference, ii. 195.
Honey - indicators, name applied to floral
markings, ii. 190.
Honey-leaves of Berberidacez, ii. 178,
—— of Droseracez, ii. 178.
— — of Ranunculaces, ii. 178.
Honeyless alluring contrivances, ii. 167 et seq.
Honey protection by intra-floral hairs, ii, 239.
— — various devices, ii. 241.
— scent, ii. 202, 207.
Honeysuckle scent, ii. 201.
Hooke, Robert, confirms Leeuwenhoeck’s
observations, i. 21.
Hooked seeds, rare, ii. 870.
— tendrils of Cobeea, i. 697.
Hooker, Bentham and, Genera Plantarum,
ii. 604.
— Himal
704.
— monograph on Welwitschia, ii. 726.
Hookeria splendens, leaf structure and
greenness, i. 387, 590.
Hop. See Humulus lupulus.
Hop-hornbeam. See Ostrya carpinifolia.
Hordeum, glumes, ii. 434.
— host of Ustilago segetum, ii. 675.
— pollination, ii. 142.
Hormidium, cromatophore, ii. 650.
— habitats, ii. 650.
Hormidium murale, habitat, i. 105.
Horminum, honey protection, ii. 241.
Hormomyia, galls caused by, ii. 529, 537, 538,
539.
Hormosiphon arcticus, habitat, ii. 621.
Hornbeam. See Carpinus.
Hornblende, i. 83.
—and lime in slate, ii. 496.
. Hornwort. See Ceratophyllum.
Horse-chestnut. See Aisculus.
Horse-shoe Vetch. See Hippocrepis.

tot]

qd

Journal on

it trees, i.

of

c See Ei

Hildebrand, and lL ck

Oxalis hybrids, ii. 565.
Hildenbrandtia, cell arrangement, i. 577.
Hildenbrandtia Nardi and rosea, incrusting,

L he
Hilum, of starch-grain, i. 460.

ef
Hortensia, of horticulturists, ii. 187.
Hortus siccus, i. 5.
Host, action of Bacteria on, i, 162.
‘—and parasite, intimacy of connection

‘between, in Lophophytum, i. 194,

Host, appearance after death of Mistletoe, i,

10.
— application of term, i. 161. ;
— behaviour towards parasites, i. 167.

\— effect of Euphrasia on, i. 179.

— how attacked by Cuscuta, i. 174.

— of Lathrea squamaria, i. 181.

— partial destruction by fungi, i. 168.
Host-root, effect of Langsdorfiia tubercle ou,

i, 187.
—— how affected by Orobanche, i. 183, 185.

) Hosts, contrivances for protection, i. 164.

— of Bartsia, i. 180.

/—of Cynomorium, chiefly maritime plants,

i i. 198.

' — of Lathrea, i. 182.

| — of Viscum album, i. 205.

Hottonia, food-absorption, i. 765.
— heterostyly, ii. 302.

. — pollen dispersion, ii. 105.

! — protective isolation by water, ii. 234.
Hottonia palustris, roots absent, i. 76.
House-leek. See Sempervivum.

Houstonia, pollen-grains, ii. 99.
Hovenia dulcis, pedicel and fruit, ii. 435.
Hoya carnosa, aids to climbing, i. 687.

p ion by leaf. i ii. 41

Humble-bee, and pollen, ii. 167.

——and Salvia glutinosa, ii. 262.

— — colour preference, ii. 195.

Humble-bees, as honey stealers, ii. 239.

Humic acid, produced by decay, i. 101.

—— some properties of, i. 101.

idity, continued, of
ous effect on plants, i. 283.

Humming-birds and honey, ii. 180.

— — and laterally-directed flowers, ii. 225.

——and pollen-sprinkling flowers, ii. 271
Humous acids, and preservation of fossil

plants, i. 262; ii. 612.

Humulus, dicecious, ii. 299.

— pollen dispersion, ii. 143.

— pollination, ii. 133.

— prickles, i. 687.

Humulus Lupulus, attacked by Sphzerotheca

Castagnei, ii. 60.

— — dextrorse twining, i. 685.

— — fruit-protecting glands, ii. 447.

—— nutation, i. 683.

—— protogyny, ii. 313.

— — seed-dispersal, ii. 854.

| — — shoots and climbing hooks, i. 688.

— — stem with Cuscuta, i. 175.

— — twining, i. 682.

Humus, constitution and facies of vegeta-

tion, ii. 498.

— limitation of availability to plants, i. 113.

— moisture retention, i. 775.

— nature of, i. 84.

of mineral suk ii. 499.
Hundred Years’ Aloe. See Agava americana.
Hungarian plains, hairiness of plants, i. 318.
—— scarcity of Mosses and Ferns, ii. 457.

lands, protected v tion, i, 451.
Hura crepitans, detonation, ii. 839.
Hutchinsia alpina, autogamy, ii. 339.

—— &c., favourite soil, ii. 496.

Hutchinsia petra, anthocyanin, i. 521.
Hyacinthus, ii. 731.

— alluring petals, ii. 170.

— epiphyllous buds, ii. 43.

= leaf-bud, emerging from soil, i. 640.

— leaves, and rain conduction, i. 94.

— roots, i. 753,

— scent, ii. 200.

| Hybridization, formative importance of cyto

plasm, ii. 494.
— general discussion, ii, 317.
— nature of, ii. 301.

'— realization of factors in, ii. 573.

. Hybrids, and origin of species, ii. 583.
— and reversion, ii. 580.

, — and season of flowering, ii. 574.

— and “transitional forms”, ii. 584.

'— artificial, number of, ii. 555.

— change in sexual conditions, ii. 575
— colours in, ii. 566. :

1 injuri-

—r

Hybrids, conditions of formation, ii. 404.
— doubling of flowers, ii. 576.
— factors in sterility; ii. 578.
— from races and species, ii. 581.
— goneoclinic, ii. 559.
— indumenta, characteristics of, ii. 564.
— in relation to grafting, i. 215.
— juxtaposition of parental characters in, ii,
561, 573.
— minute structure, ii. 565.
— misco tions ec ing, ii, 577.
— misstatements concerning, ii. 557.
— natural occurrence and distribution, ii.577,
_ 582, 585.
— non-inherited characteristics, ii. 574,
— parent proportions in, ii. 558,
— permanence of, ii. 587,
— potential fertility, ii. 579.
— produced by grafting, ii. 569.
— pseudo-hermaphrodite flowers in, ii. 578.
— starch-grains in, ii. 566.
— tendency to vegetative propagation, ii. 458.
— ternary, ii. 560.
— variation, ii. 576.
Hydnew, appearance of, i. 112,
—hymenium, &c., ii. 688.
Hydnora Africana, South Africa, i, 199.
Hydnora Americana, South Brazil, i. 199.
Hydnora triceps, South Africa, i, 199,
Hydnoraces, ii. 762.
— anthocyanin, i. 483.
— nature of scents, ii. 199.
Hydnum, raising power, i. 514.
Hydnum imbricatum, ii. 21, 685.
—-— respiratory heat, i. 498.
Hydra, symbiosis with plants, i. 254.
Hydrangea Japonica, sterile flowers, ii. 187.
Hydrangea quercifolia, protection of pollen ,
from wet, ii. 111, 112.
— — sterile flowers, ii. 187.
Hydrilla, attachment, i. 77.
— spiny leaves, i. 438.
Hydrilla verticillata, pollination, ii. 133.
Hydrocarbons, nature of, i. 453.
Hydrocharidacez, ii. 105.
— distinctive characters, ii. 739.
— pollination, ii. 133.
Hydrocharis Morsus-rane, ii. 739.
—— anthocyanin, i. 521.
—— formation of winter-buds, ii. 804.
— — habit, i. 666.
— — leaf and transpiration, i. 288.
— — leaf-rosettes, i. 412.
— — position of stomata on leaves, i. 280.
— — protective isolation by water, if. 234.
— — sprouting of winter-buds, ii. 805.
—— venation, i. 633.
Hydrocotyle Asiatica, venation, i. 631.
Hydrocotyle vulgaris, entire plant, ii. 789.
Hydrodictyacee, ii. 640.
— description, ii. 639,
Hydrodictyez, ii. 606.
Hydrodictyon, Klebs’ observations on repro-
duction, ii. 482.
— life-history, ii. 640.
— multiplication, i. 588,
— reproduction, i. 574. 1
— thallidium, ii. 23.
Hydrodictyon utriculatum, ii. 24, 640.
— — swarming of protoplasm, i. 36.
Hydrogen, combined with carbon, i. 453,
Hydropeltiding, of Braun, ii. 605,
* Hydrophyllacez, ii. 771.
HydrophyLium, emerging of leaves from soil,
i, 639, i
— unfolding leaves, i. 351.
Hydrophytes, absorption of carbonic acid, i.
367.

|
— ash of, i. 66.

—as lime accumulators, i. 260.

— attachment in relation to nutrition, i. 77. |
— floating contrivances, i. 638. !
— free and submerged, i. 76.
— mechanical tissue, i. 735.
— nutrition, i. 77. ‘
— parasites on, i 169.

— require large supply of food-salts, i. 78. |

'| — hybrids, ii. 584.

| _ — of Entomophthora, ii. 672.
| —— of Erysiphez, ii. 59.
| ——prey upon cell-walls, &e., i. 167.

INDEX,

Hydrophytes, saprophytic, non-green, at-
tacked by species of same group, i. 170,

— swelling of dead cell-membranes and
retention of mud, i. 267.

— unicellular, movements and light, i. 382.

— venation, i. 636.

— where very abundant, i. 104,

Hydropterides, ii. 709, 710.

— of Braun, ii. 605.

— sorts of spores, ii. 704.

Hydrotropism, in roots, i. 775.

Hydroxyl, i. 454,

Hydrurus, in cascades, i. 79.

— structure, i. 590.

Hygrobie, ii. 784.

rie mericarp of Erodium used as,
1 .

Hylocomium, ii. 480.

Hylocomium splendens, ii. 15, 700.

— — habitat, i, 109.

Hymenial layer, and respiration, i. 498.

Hymenium, luminous, i. 503.

— of Amanita, portion, ii, 21.

— of Hymenomycetes, ii. 688.

Hymenocystis, protection of sporangia, ii. 13.

Hymenomycetes, as Lichen-fungi, ii, 693.

— basidia, ii. 680.

— characteristics, ii. 687,

— luminous, i. 502.

— range of forms, ii, 688.

— respiration experiments, i. 498,

— similarity of spawn, dissimilarity of fructi-
fications, ii. 491,

| Hymenophyllacez, absorption-cells in, i. 86.

— description, &c., ii. 705.

— greenness of prothallia and habitat, i.
384,

— in Blue Mountains, Jamaica, ii. 457.

— sori, 11. 10.

Hymenoptera and aminoid scents, ii. 207.

— and Calceolaria Pavonii, ii, 379.

— eaters of pollen, ii. 167.

— gall-formation, ii. 527.

Hyoscyamus, calyx and fruit, ii, 434,

— corolla and autogamy, ii. 366.

— cross-fertilization, ii. 305.

— pollen deposition, ii. 278.

Hyoscyamus albus and frost, ii. 407.

Hyoscamus niger and cattle, i. 451.

— — odour, i. 431.

Hypanthium, forms of, ii. 780.

Hypecoum, corolla and autogamy, ii. 369.

— nectaries, ii. 178.

Hypecoum grandiflorum, autogamy, details,

ii. 370

| —— lower, ii. 181, 369.

Hypecoum pendulum, weather and auto-.
gamy, ii. 391.

Hypecoum procumbens, honey concealment,

ii, 182
Hypericinez, pollen-grains, ii. 102.
Hypericopsis persica, salt on leaves and stein,
i, 236. °
Hypericum, alluring floral tissue, ii. 170.
— autogamy, ii. 340.

— staminal insect platform, ii. 230.
— twisting of internodes, i. 417.

| Hypericum humifusum, weather and auto-.

gamy, ii. 391.

'| Hypericum olympicum, stamen, ii. 87. t
‘| Hypericum perforatum, autogamy, ii. 340,

Hypertrophy, caused by Fungi, ii. 519.
Hyphe, fungal, attacking plants, i. 165.
—— attraction by ovules, ii. 414.

'| ~— constitute mycelium, i. 99.

—— development from spore, i. 163.
—— mechanical changes due to, i 265,
— — mechanical force, i. 513.

— — modes of growth, i. 589.

—— of Empusa Muse, ii. 672.

—— symbiosis with roots of Phanerogams,
i. 249,
—— tips of, decomposing power, &c., i. 164.

955

Hyphe of Lichen, chemical and mechanical
action, i. 257.

— of Zygomycetes, ii. 673.

Hypheene coriacea, caudex, i. 714.

Hyphzene thebaica, inflorescence, i. 745.

— — Nile, caudex, i. 714.

Hypheothrix, schizomycetous member of
sub-aqueous Lichen-like plants, i. 248.

Hyphodromous venation, i. 636.:

Hypnosporangium, of Botrydium, ii. 643.

Hypnum cordifolium, home of, i. 105.

Hypnum falcatum, lime incrusted, i. 260.

Hypnum fiuitans, &c., and hybridization, ii.
583.

Hypnum giganteum and H. sarmentosum,
home of, i. 105.

Hypnum molluscum, absorption of aqueous
vapour, i. 218,

Hypnum rugosum, parthenogenesis, ii. 464.

Hypnum triquetrum and H. Crista-cast-
rensis, habitat, i. 109.

Hypnum uncinatum and H. reptile, habitat,
i. 109.

Hypocheris, autogamy, ii. 372, 375.

— maculata, opening and closing, ii. 218, 217.

Hypochlorin, from chlorophyll, i. 372.

Hypocotyl, i. 655.

— and cotyledon-stalks, relative proportions,
i. 621.

— buds on, ii. 28.

— functions, i. 650.

+ of Rhizophora, i. 602, 604.

Hypocrateriform, applied to flowers, ii. 111.

Hypoderma Lauri, habitat, i. 118.

Hyssopus officinalis, colour and bees, ii. 195.

Hysterophyta, of Endlicher, ii. 604.

I.

Iberis amara, light and growth, ii. 508.

— — peripheral flowers, ii. 186.

—— umbellate raceme, ii. 184.

Iberis gibraltarica, peripheral flowers, ii.
186.

Iberis umbellata, peripheral flowers, ii. 186.

Ice, as preservative agency, i. 262.

— in frozen plant, i. 540.

— melting by plant growth, i. 500.

Iceland Moss. See Cetraria islandica.

Ice-plant. See Mesembryanthemum cristal-
linum.

Ichneumon, pollinates Listera, ii. 256.

Ichneumon-fly, protection of bud-gallagainst,
ii. 542.

Ichthyosoma. See Sarcophyte sanguinea.

Idioplasm, views regarding, ii. 493.

Dex Aquifolium, bristle-like teeth, i. 433.

—— cuticle of leaf, i. 310.

Ilecebrum, prostrate shoot, i. 664.

Iecebrum verticillatum, sub-aqueous fer-
tilization, ii. 391.

“Tlegitimate union”, in crossing, ii. 405.

‘| Illicium anisatum, follicle, ii. 431.

Hllicium religiosum, poisonous, ii. 488.

.| Iumination, adaptation to, i. 394,

— bright, effects on plants, ii. 407.

— effect of varying intensity, i. 381.

— varied adaptation of leaves to, i. 423.

Imagination, value of, i. 17.

Imbibition, freedom of, i. 88.

Immortelle. See also Helichrysum arenarium.

Immortelles, ii. 766.

— hairy, time of appearance in dry regions,
i. 318.

— hairy covering in summery, i. 319.

Impatiens, and insect visits, ii. 223.

— cleistogamy, ii. 393.

— pollen deposition, ii. 277.

— root-hairs, i. 91.

Impatiens glanduligera, i. 656.

| —— cross-fertilization, ii. 306.

Impatiens Noli-tangere, cleistogamy, ii. 394.
— — cross-fertilization, ii. 306.

— — leaf and illumination, i. 286.

— — seed-dispersal, ii. 835.

— — sheltering of pollen, if. 108, 109.

956

Impatiens parviflora, inequality of leaves,
and use, i. 422.

— — leaf-mosaic, i. 411.

Impatiens tricornis, cross-fertilization, ii. 306.

— — protection of honey, ii. 232.

—— stem, i. 656.

Imperfect flowers, ii, 294.

Imprisonment of insects by flowers, ii. 164.

Incrustment, type of community, ii. 889,
894.

Indehiscent dry fruit, ii. 429.

Indian Banyans, i. 758.

— Ocean, reddened by Trichodesmium, i. 389.

Indian Shot. See Canna.

India-rubber, latex of Ficus, i. 470.

India-rubber Fig. See Ficus elasti

INDEX.

Internodes, twisting of, i. 417.

Intine, of pollen-grain, ii. 100.

Introrse, of anthers, ii. 95.

Intussusception, i. 44.

Inula, decurrent leaves, i. 336.

— hairiness, i. 317.

— hermaphrodite and pistillate flowers, ii.
296.

— hybridization, ii. 316.

Inula viscosa, varnish-like coating, i. 312.

Invertin, enzyme of yeast, i. 465.

Investments, of plants, ii. 564.

Involucres, and nocturnal radiation, i. 530.

Iodine, effect on plants, i. 73.

— in plants, i. 66, 68, 71.

I ha plant, ii. 764.

Indigofera, explosive flowers, ii. 267.

— freezing, i. 546.

— leaf, diurnal positions, i. 534.

Individual, meaning in Botany, ii. 5.

— development, and phyllogeny, ii. 608.

Indol, nature of, ii. 199.

Indoloid scent, ii. 199, 207.

Indumenta, of hybrids, characteristics, ii.
564,

Indumentun, or investment, ii. 564,

Indusium, nature of, ii. 13.

— of Fern sorus, ii. 705.

Infertility, of plants under cultivation, ii.
402.

Inflorescence, application of term, i. 641.

— detachment, i. 748.

— nature of, i. 737.

— sorts of, numerical relations, i. 745.

— sympathetic movement of various parts,
i. 744,

Inflorescences, and nocturnal radiation, i.

—of Balanophora, resemblance to Fungi, i.

— periodic bending, i. 531; ii. 120.

Infusoria, derivation of term, i. 21.

— prey of Utricularia montana, i. 123,

Inga, pollen-chambers, ii. 90.

Innovatio, i. 596.

Tansbruck, floral clock for, ii, 216.

Inorganic subsvances, absorption of, i. 60.

Insectivorous plants, and pepsin, i. 465.

—— habitat in relation to supply of nitrogen,

i, 158.

—— with pitchers or ascidia, i, 123.

Insect-galls, ii. 527 et seq.

Insect-visitors of Asclepiads, ii. 258,

Insect visits and duration of flowers, ii. 214.

Insects, absence of, and vegetative offshoots,
ii, 459,

— and anther-lids, ii. 129.

— and colour sense, ii. 195.

— and mixed pollination, ii. 403.

—and plants, mutual interdependence, i.
255.

—and pollen-sprinkling flowers, ii. 271,

— and pollination, i. 461; ii. 95.

— and scents, ii. 207.

= ts for reception, ii. 226, 227.

— as hosts of parasitic Fungi, i. 168.

— imprisonment by flowers, ii. 163, 164.

—in Alps, ii. 400.

— method of visiting flowers, i. 742.

— olfactory organs, ii. 204,

— parasitic, and stamens, ii. 87.

— pollen-collecting and devouring, ii. 133,

— probosces and honey, ii. 179.

— smearing with pollen, ii. 245,

— structural correlation to flowers, ii. 152.

Insolation and elevation, i. 525.

Instinct, examples of operation of, i. 53.

Tustitutiones Rei Herbariw, by Tournefort,
ii, 601,

Integument, of Gymnosperm ovule, ii. 438.

— of ovule, i. 644; ii, 72, 81, 84.

— of seed, in Cuscuta, i. 173.

Intercellullar spaces, ice in, i. 540.

Interchange, of materials between root-hairs
and substratum, i. 88,

Internode, bairs on, in Stellaria media, i, 227.

— of stem, i. 396, 658.

Ipomea, pollen-grain, ii. 100.

Ipomea muricata, prickles, &c., i. 687.

Ipomea purpurea, autogamy, ii. 336.

—— opening of flower, i. 212.

Iriartea, geographical distribution, ii. 740.

Iridacez, autogamy in, ii. 372.

— characteristics, ii. 734.

— heterostylism, ii. 398.

Iridez, equitant leaves, i. 336.

— hybrids among, ii. 583,

Tridescence, of Phyllocladia, i. 388,

Iris, extrorse anthers, ii. 95.

— germination, i. 604.

— grafting experiments at Innsbruck, ii.

o71,

— green cells, arrangement, i. 471.

—humble-bees and pollen, ii. 247.

— hybridization and flower colours, ii. 568.

— nectary, ii. 176.

— leaf twist, i. 429.

— pollen deposition, ii. 280.

— pollen-grains, ii. 99.

— protection of pollen from wet, ii. 111.

— stigma, i. 645; ii. '729.

Tris arenaria, opening and closing, ii. 212.

Iris Florentina and 1. Kochii, ii. 568, 572.

Tris Germanica and I. sambucina, colour of
flowers and hybrid, ii. 568.

— — flower, ii. 246.

— — wax on leaves, i. 192.

Iris Kochii, graft on I. Florentina, ii. 572.

Iris odoratissima, scent, ii. 201.

Iris pallida, wax on leaves, i. 292.

Iris pumila, variability of floral colour, ii.
569.

— — wax on leaves, i. 292.

Tris sibirica, sheltering of pollen, ii. 109.

Iris variegata, Pl. VI.

Iron, i. 73, 83, 258, 261.

— in chlorophyll, i. 371.

— oxide of, in dust, i. 81.

— relation to chlorophyll, i. 67.

— salts, i. 274.

— storing by Bacteria, ii. 624.

Tron hydroxide,accumulation through plants,
i. 261.

Tron-ore, accumulation through plants, i.

Irrigation of rain-water, i. 97.

Ismene, scent, ii. 201.

Isoétacew, descriptive details, ii. 716.

Isoétes, cambium-like zone, ii. 717.

Isoétes lacustris, whole plant, &c., ii. 716.

Isogametes, of Chlorochytrium, ii. 637,

— of Gonium, ii. 631.

Isoloma, hybrids, ii. 575.

Isoplanogametes, of Chlorophyces, ii, 628.

~— typical conjugation in Stephanosphera,
ii, 632.

Isopyrum, movements of stamens, ii. 250.

— nectaries, ii. 179,

Isopyrum thalictroides, leaf andillumination,

i, 286.

— — protection of pollen, ii. 120.

Istria, Calluna vulgaris on coast, i. 526.

Istria, flora of, i. 306,

— interior, absence of heaths, i. 307,

— Spartium scoparium in, ii. 330.

Italian flora, general grayness of, ii. 317.

Ivy. See Hedera.

Ivy-leaved Duckweed. See Lemna trisulca,

J.

Jack-fruit. See Artocarpus integrifolia.

Jacquin, grafting experiment with Ginkgo,
ii, 572.

Japanese and artificial crossing, ii. 555.

— Maidenhair Tree. See Ginkgo biloba.

— Paper Mulberry. See Broussonetia papy-
rifera.

—Saxifrage. See Saxifraga sarmentosa.

Jasminacee, ii. 771.

Jasminum, freezing, i. 546.

Jasminum nudifiorum, weaving stem, i
672.

Jasminum officinale, scent, ii. 200.

Jatropha, stinging hairs, i. 441.

Jew’s-ear Fungus. See Auricularia sambu-
cina,

Judas Tree. See Cercis Siliquastrum.

Juglans, bud-scales, i. 626.

— cotyledons, i. 608.

— fertilization porogamic, ii. 413.

— fossil, i. 636.

— mite-galls, ii. 529.

—monecious, ii. 297.

— poll and di

— pollination, ii. 133.

— protection of pollen, ii, 119.

— protogynous, ii. 313.

Juglans regia, anthocyanin in buds, i. 484.

— — inflorescences, i. 742.

— — pollination, i. 741.

—— seed protection, ii. 446.

—— stamen, ii. 87.

— — unfolding leaves, i. 349.

—— vernation, i. 350.

Juliflore, of Braun, ii. 605.

“‘ Jumping Bean”, ii. 844.

Juncacee, distinctive characters, ii. 730.

— from chalk, ii. 613.

Juncus, cleistogamy, ii. 392.

— germination, i. 604.

— hybrids in, ii. 583.

— pollination, ii. 133.

— protogynous, ii. 312,

— switch-plants, i. 330.

— venation, i. 634.

Juncus alpinus, &c., and galls of Livia Jun-

corum, ii. 547.

— — bulbils, ii. 454.

Juncus bufonius, cleistogamy, ii. 394.

Juncus castaneus, anthocyanin, i. 522.

Juncus diffusus, hybrid of J. effusus x J.
glaucus, ii. 586.

Juncus glaucus, mechanical tissue arrange-
ment, i. 731.

Juncus Jacquinii, anthocyanin, i. 522.

— — pollen tetrads, ii. 97.

Juncus lamprocarpus, habit and habitat, ii.
502.

ii. 94, 148.

Juncus monanthos, &c., favourite soil, ii. 496.

Juncus supinus, bulbils, ii. 454.

— — habit and habitat, ii. 502.

Juncus trifidus, anthocyanin, i. 522,

— — habitat, i. 113.

Junger various
i. 591.

Jungermannia polyanthos, structure, i. 590.

Jungermanniacex, description, ii. 698.

Junghuhn, discovers several Balanophores
in Java, views concerning, i. 190.

Juniper-Mistletoe. See Viscum Oxycedri.

Juniperus, ii. 725.

— and Gymnosporangium, ii. 686.

~ dicecious, ii. 299.

— egg-cells, ii. 419,

— embryo development, ii. 438.

— fertilization, ii. 420,

— fleshy cone, ii. 440.

— mutilation by ruminants, ii. 515.

— pollen-sacs, ii. 89,

— pollen storing and dispersion, ii. 146,

— protection of ovules, ii. 72.

— protection of pollen, ii. 117,

— specific value of leaf anatomy, ii, 565.

shoots of,

Juniperus chinensis, variety of foliage-leaves
on successive shoots, ii. 471.

Juniperus communis, i. 487.

——and galls of Lasioptera juniperina, ii,

547, 552.

—-—and J. sabinoides, hybrid, ii. 565, 583,

—— branch with cones, ii. 442,

— — gall of Gymnosporangium, ii, 521.

—— &c., waxy stripes on upper leaf-surface,

i, 292.

Juniperus excelsa and J. japonica, &c.,
variety of foliage-leaves on successive
shoots, ii, 471.

Juniperus Kanitzii, hybrid, ii. 565, 583,

Juniperus nana, and snow, i. 550.

— — &ce., resistance to cold, ii. 489.

Juniperus Oxycedrus, host of Viscum Oxy-
cedri, i. 210.

Juniperus phoenicea, and resistance to cold,

ii. 489.
Juniperus Sabina, host of Gymnosporangium,
ii, 522.

— — offensive odour, i, 431.

—-—stamen, ii. 87.

Juniperus Virginiana, pollen-storing and

dispersion, ii. 146.

—— protection of pollen, ii. 125,

Jurassic flora, i. 636.

Jurinea mollis, Pl. VI.

— — protection by ants, ii. 243,

Jussieu, De, and natural system of classifica-
tion, i. 15; ii, 602.

Jussieua, pollen tetrads, ii, 97.

Jute. See Corchorus olitorius,

K.

Kalmia, pollen tetrads, ii. 97.
Kamptodromous, venation, i. 630.
Kangaroo, pollination by, ii. 230.
Kant, views on hybrids, ii. 571.
Kaulfussia, sporangia, ii. 709.
Keel, of papilionaceous flower, ii. 94, 228.
Kernera saxatilis, bending of stamen-fila-
ments, ii. 250.
— — flower, ii. 249.
—— inflorescence, ii. 184, 193.
—-— pollen deposition, ii. 278.
Kew, Cycads at, ii. 720.
— flowering of Amorphophallus, ii. 745.
— flowering of Ephedra and Gingko biloba,
ii. 474,
Killarney Fern. See Trichomanes radicans.
Kitzbiihel, classic work of Unger at, ii. 495.
Klebabn, observations on “Flowers of the
Sea”, ii. 622.
Klebs, experiments with Vaucheria, ii. 482.
Kleinia articulata, vegetative propagation,
ii. 823.
Knautia arvensis, distribution of sexes, ii.
298.
——stamens and Peronospora violacea, ii.
524,
Knawel. See Scleranthus.
Knightia excelsa, height, &., ii. 751,
Kniphofia, appearance of spikes, ii. 731,
Knotweed. See Polygonum.
Keeleria, pollination, ii. 142.
Keelreuter, early experiments on hybrids, ii.
579.
Keelreuteria paniculata, scale-leaves, i. 626.
— — seedling, i. 9.
Koniga spinosa, hairs, i. 321.
—— spinosity, i. 444.
K6nigsblume, why so called, ii. 753.
Kurdistan, steppes of, hairiness of plants, i.
318,

Kurosiur, blueness of water, i. 389,

L.

Labellum of Cypripedium calceolus, ii. 249.
— of Orchidaces, ii. 253, 736.

— of Zingiberacem, ii. 736.

Labiate, ii. 71.

INDEX.

Labiate, autogamy in, ti. 356,
— bees and pollen, ii. 247.
— calyx and fruit, ii, 434,
— coloured bracts in, ii. 183,
— decurrent leaves, ii. 336.
— dehiscence of pollen-sacs, il. 92.
— dichogamy in, ii, 313.
— direction of flowers in, ii. 225.
— distribution of sexes, ii, 298.
— flowers and nocturnal radiation, i. 530.
— fruit-dispersal, ii. 842.
— grooving of stem, i. 95.
— hybrids among, ii. 585.
— massing of flowers, ii. 186,
— “Phrygian”, i. 444.
— pollen deposition, ii. 277.
— pollen-grains, ii. 99.
— seed protection in, ii. 446.
— specially hairy genera, i. 317,
Labour, division of, i. 367.
—-— and higher development, ii. 598.
— — in associated protoplasts, i. 27.
—— protective, i. 443.
Labrador felspar and lime in slate, ii, 496.
Laburnum, phyllotaxis, i. 400.
Lactarius, latex, i. 470, 689.
Lactarius deliciosus, non-poisonous, ii. 488.
Lactarius scrobiculatus, raising power, i. 514.
—— respiration experiments, i. 498.
Lactarius torminosus, poisonous, ii. 488,
Lactic acid, from milk, i. 506.
Lactuca, geitonogamy, ii. 319.
Lactuca muralis, anthocyanin, i. 520.
Lactuca sativa, latitude and closing, ii. 218.
— — protective sticky latex, ii. 234,
Lactuca scariola, position of leaves, i. 337.
—— protective sticky latex, ii. 234,
Lactuca virosa, laticiferous tubes, i. 471.
Lacune, in mesophyll, i. 279.
Ladder-type of conjugation, ii. 657.
Lady Fern. See Athyrium Filix-fomina.
Lady’s-fingers. See Anthyllis Vulneraria.
Lady’s Mantle. See Alchemilla vulgaris.
Lelia gracilis, porous cells of root, i. 219.
Lelia Perrinii, ovary, ii. 83,
Lagarosiphon, pollination, ii. 133, 739.
Lagenaria, fruit, ii. 452.
Lagenidium Rabenhorstii, life-history, i.169.
— — life-cycle, ii. 671.
— — on Spirogyra, ii. 668.
Lamelle, of Agaricinez, ii. 689,
Lamina, of leaf, i. 595.
— — and transpiration, i. 595.
Lamine, vertical, extra Australian, i. 336,
Laminaria digitata, thallus differentiation,
ii. 661.
Laminaria saccharina, ii. 662.
Laminaria-zone, ii. 661.
Laminariacez, habit, i. 587.
— reproductive cells, ii. 661.
— with perforated fronds, ii. 662.
Lamium album, anthocyanin, i. 523.
— hanical tissue t, i, 729.
Lamium amplexicaule, cleistogamy, ii. 392.
Lamprococcus, coloured bracts, ii. 184.
Lamprococcus miniatus, scarlet flower, ii. 196.
Lampsana, time of closing, ii. 221.
Lampsana communis, altitude and opening,
ii. 218.
Land-breeze and dispersion of pollen, ii. 134.
Land-plants, absorption of food-salts, i. 82.
—— adaption to absorption of carbon-diox-
ide, i. 62.
——and water-plants, nutrition compared,
i. 78.
—— relative number, i. 56,
Langsdorffia, balanophorin, “‘siejos”, &., i.
188.
— intimate connection with host, i. 188.
Langsdorffia hypogea, i. 187.
—— geographical distribution and habitat,
i. 186.
Lapland, flora of, i. 6.
Lappa, hybrids, ii. 585.

| Lappa major, hooked capitulum, ii. 873.

Lappa pubens, hybrid of L. minor x L. to-
mentosa, ii. 586.

957

Lappago racemosa, fruits and dissemination,
i. 615.
— — hooked fruit, ii. 871.
Larch. See Larix.
Larch-disease, ii. 522.
Larch root, elevating block of stone, i. 515.
Larix, and grazing animals, i. 445.
—arrangement of foliage-leaves, ‘short
branches”, “long branches”, i. 93; ii. 471.
— effect of Peziza Willkommii on, i. 168.
— needle-tufts, ii. 725.
Larix europzea, ii, 483.
— — age, i. 722.
— — bract and ovuliferous scales, ii. 441.
—— branch and cone, ii. 443.
— — dimensions, i. 722.
— — host of Peziza Willkommii, ii. 522.
— — ovuliferous scale, ii. 721.
Larkspur. See Delphinium.
Larve, in solid galls, food-supply, ii. 526.
— of moths, feed on seeds of Yucca, i. 255.
Laserpitium, geitonogamy, ii. 323.
Laserpitium latifolium, anthocyanin, i. 522.
— — flowers, sexual conditions, ii. 296.
—— seed dispersal, ii. 853.
Lasiagrostis, boring runners, i. 516.
Lasiagrostis Calamagrostis, folding of leaf,
i. 344.
—— isolated colonies, i. 528.
—-— leaf, vertical sections, i. 343.
Lasioptera juniperina, cluster-galls on Juni-
perus communis, ii, 547.
Laterally-directed flowers and insect visitors,
ii. 225.
Lathra, anthocyanin, i. 483.
—a parasite, i. 138.
— capturing apparatus, i. 137.
— colour and surroundings, ii. 195.
— pollen sprinkling, ii. 272.
— scaly stem, i. 652.
Lathrea clandestina, geographical distribu-
tion, i. 183.
—— suckers, i. 183.
Lathra Squamaria, as parasite, &c., i. 181.
— — geitonogamy, ii. 330.
—— inflorescence and flowers, ii. 329.
— — relationships and description, i. 135.
— — stamens, ii. 329.
Lathrophytum, Peckoltii, leafless, i. 196, 597.
Latbyrus, how protected, i. 451.
— keel movements and pollen-brush, ii. 252.
— phyllodes, i. 335.
Lathyrus Aphaca, leaf-tendrils, i. 693.
— — stipules, i. 637.
Lathyrus odoratus, colour-contrast of flower,
ii. 190.
—— scent, ii. 203.
Laticiferous tubes, connection with palisade-
cells, Pl. I., i. 472.
— — functions, i. 470.
— — Lactuca, i. 471.
Latitude, and dates of flowering, i. 519.
—and retardation of vegetation, i. 565.
Lattice-forming stem, i. 678.
Lattice-leaf plant. See Ouvirandra fenes-
tralis.
Laudatea, form of Cora, ii. 695.
Lauracez, dehiscence of pollen-sacs, ii. 93.
— pollen-chambers, ii. 90.
— protection of pollen, ii. 124,
Laurel-tree. See Laurus nobilis.
Laurus, cotyledons, i. 608.
— protection of pollen, ii. 125.
Laurus nobilis, dehiscence of pollen-sacs, ii.
93.
— — distribution of sexes, ii. 298,
Lavandula, hairiness, i. 317,
— scent, ii. 203.
Lavandula pedunculata, &c., alluring bracts,
ii. 188.
Lavandula Stoechas, flower spike, ii. 184.
Lavender, oil of, ii. 203.
— Cotton, i. 5.
— scent, ii. 203.
Law of form, of plants, i. 567.
Layers, perpetuation of hybrids by, ii. 556.
Leaf, adaptation to illumination, i. 286, 394.

958

Leaf, adaptive modifications, i. 637.

— arrangement of channels, i. 93.

— botanical definition, i. 595.

— compound, and nocturnal radiation, i. 532,

— distinctive features, i. 649.

— effect of climate on, i. 325.

— electric currents in, of Dionza, i, 151.

— evolution of meaning, i. 593.

— fistular, advantage of, i. 428,

— fleshy, i. 327.

— hairy covering on upper surface in relation
to habitat and climate, i. 315.

—metamorphosis of. See Metamorphosis
and also Leaves.

— movement in Pinguicula, i. 142.

— of Aldrovandia and Dionza, i. 150.

— of Drosera, i. 145.

— of Drosophyllum, i. 154.

— of Pinguicula, structure, i. 141.

— of Saxifraga Aizoon, mechanism for pre-
vention of desiccation, i. 234.

— palmate, vascular bundles, i. 649.

— peltate, vascular bundles, ii. 649,

— pinnate, diurnal positions, i. 534,

—— vascular bundles, i. 649.

— position and wind, i. 427.

— regarded as fundamental organ, i. 10,

— scabrous, i. 440.

— spiral twisting, i. 429.

— stomata, chiefly on under side, i. 290.

— strengthening of, i. 426,

— subtending, i. 641.

— venation, i. 631, 633.

— young, position, i. 538.

Leaf-blade, change of inclination, i. 418.

—— change of position, i. 338.

—— perforation and light, i. 413.

—— shape, i. 627 et seq.

—— vertical, in Myrtacez, &c., i. 335.

Leaf-cuttings, propagation by, ii. 41.

Leaf-fall, changes correlated with, i. 358,

— — effect of frost, i. 359.

—— effect of habitat, i. 357.

—— excretory nature of, i. 486.

—— Horse-chestnut, i. 361.

—— separation-layer, i. 359.

—— thermal constants, i. 560.

Leaf-green=chlorophyll, i. 375.

Leaflets, movements, i. 533.

Leaf-like structures on leaves, i. 649,

Leaf-mosaics, i. 410, 411.

— — unequal-sized leaves, i. 421.

— — unsymmetrical and unequal-sized leaves,

i. 422

— — unsymmetrical leaves, i. 420.

Leaf-movements, of Mimosas, i. 339.

—— various causes and advantages, i. 538,

Leaf-position, displacement by torsion, i. 407. | |

Leaf-prickles, i. 439.

Leaf-shape and phyllotaxis, i. 408.

Leaf-sheath, i. 595,

— — of Grasses, i. 427.

Leaf-skeletons, i. 628.

Leaf-stalk, and twisting of internodes, i. 417.

—— chief duties, i. 637.

— — elastic, advantage of, i. 428,

— — tendril, i. 692.

— — — sensitiveness to contact, i. 695.

Leaf-tendril, i, 692.

Leaf-unfolding, Beech, i. 353.

— — Tulip-tree, i. 352.

Leaf-veins, protective arrangement in young
leaves, i. 351.

Leaves, absorption of rain and dew, i. 370.

— asymmetrical, advantage of, i. 421.

— autumnal colour, meaning of, i, 485.

— bi-lateral structure, i. 279.

— change of direction during development,
i. 326.

— change of function, i. 450.

— channelling of stalks and rain conduction
i. 93.

— compound, mo of 1

+ fat:

i, 533.

INDEX.

| Leaves, development of, i. 648.

— diurnal movements, i. 532.

— erect, need for protection, i. 428.

— floating, necessity for increased transpira-
tion, i, 288,

—— position of stomata on, i. 280.

— floral, i. 640.

— foliage, water-absorbing structures of, i. |
231.

— form and position of transpiring, i. 325.

— in tropics, size of, in correlation to mois-
ture of the air, i. 287.

— metamorphoses of, i. 11.

— — and division of labour, i. 594,

— motile, distribution of stomata on, i. 281.

— mutual accommodation, i. 395.

—of Palms, structure in relation to trans-
piration, i. 288.

— of Water-lilies, shadows of, i. 289.

— of Welwitschia mirabilis, i, 726.

— old and young, i. 347.

— opposite arrangement, i. 399.

— position and inclination of twigs, i. 416.

— position to light, i. 409.

— protection against crushing, i. 428.

— rolled, protection of stomata from mois-

ture, i. 300.

| —— transverse sections, i. 301.

—— wide distribution of plants with, i. 303.
— segmentation and light, i. 412.

— spiral arrangement and rain conduction,

i. 96,

——— examples, i. 398,

— submerged, cause of elongation, ii. 505.

— succession in cones, &c., i. 402,

—succulent, loss of bulk through loss of
water, i, 216. -

—ternate, diurnal positions, i. 534.

— unfolding, i. 347, 34u.

— upright, distribution of stomata on, i. 281.

— variety of weapons, i. 434.

— which retain dew and rain, i. 228.

| — whorled and radical, rain conduction of,

i. 95.
Lecanora esculenta, ii. 695.
—— in desert, i. 555.
— — the Manna-lichen, ii. 810.

| Lecidea, situation on a marble column, i.
7.

Lecidea geographica, a Crustaceous Lichen,
i, 244,

Lecideas, Crustaceous Lichens, ii. 694.

Ledum, pollen tetrads, ii. 97.

| Ledum ‘palustre, and Exobasidium Vaccinii,

ii, 527.

| —— fading of flower, i. 743.
| —— felt-work of leaves, i. 302.

Leeuwenhoeck, observations of, i. 21.

| “Legitimate union” in crossing, ii. 405,

Legume, nature of, ii. 432.

Legumin, of pulse seeds, i. 458.

Leguminosz, ii. 780.

— fruit protecting glands in, ii. 447.

— seed-dispersal, ii. 837.

— stipules, i. 448,

— tubercles and Bacteria, ii. 624.

Leh, Kashmir, temperature in sun, i, 525.

Leitneriacez, ii. 758.

Lemanea, in cascades, i. 79.

Lemanea fluviatilis, as mud-collector, i. 267.

Lemua, rarity of flowers, ii. 457.

— seeds and heat, i. 555.

— swimming habit, i. 669,

Lemna gibba, roots, i. 754,

Lemna minor and L. polyrrhiza, adaptation
to change of habitat, i. 76.

— ~ chlorophyll in roots, i. 766.

Lemna polyrrhiza, anthocyanin, i. 521.

—— roots, i. 754,

Lemna trisulca, absorbent cells, i. 766.

—— and Chlorochytrium, ii. 637.

—— chlorophyll granules, positions, i. 382.

L distinctive characters, ii. 745,

— crumpled and rolled, i. 349.
— cylindrical, i. 327.

— deciduous, i. 347.

— decussate arrangement, i. 398.

Lennoace, ii. 768.
Lentibulariaces, ii. 171.

— autogamy in,.ii. 356,

— deposition of pollen in, ii. 280,

| Lentil.

Lentibulariacez, epiphyllous buds, ii. 43,
See Ervum.

Lentinus, origin of fructification, fi. 689.
Lenzites sepiaria, in wooden conduits, i. 117.
Leocarpus fragilis, external coating, i. 569.
—— plasmodium, ii. 618, 491.

| —— sporangia, ii. 491.

Leontice, germination, i. 622.
Leontodon, geitonogamy, ii. 319.

| Leontodon hastile, autogamy, ii. 361.

—— capitula and radiation, i. 530.

| Leonurus heterophyllus, guidance to honey,

ii. 248,
Lepidium campestre, autogamy, ii. 335.
Lepidium crassifolium, and animals, i, 432.
Lepidium Draba, and animals, i. 432, ~
——gall-mites and flower metamorphosis,
ii, 548.

1 Lepidium latifolium, radical buds, ii. 28.
| Lepidium sativum, cotyledons, i. 621.

—— light and growth, ii. 508.

| —— seed cement, i. 615.

| Lepidodendracez, characteristics, ii. 716.
| Lepigonum marginatum, seed, ii. 423.

| —— seed appendages, ii. 424.

Lett
648.

Leucadendron, vertical leaf-blades, i. 335.

Leucadendron argenteum, mechanism for
dispersal, ii. 856.

Leucanthemum vulgare, colour-contrast in

capitulum, ii, 191.

—— elevation and coloration, ii. 511.

Leucin, i. 263,

— an amide, i. 458.

— nature of ii. 199.

Leucobryum, absorptive apparatus, its struc-
ture, modes of action, purpose, i. 220.

— porous cells, i. 219.

Leucodon sciuroides, eee bodies, ii. 23,
458.

Leucojum, sntoeyouse ii. 311.

Leucojum vernum, ii. 729.

—— colour-contrast in flower, ii. 190.

— — flower, ii. 170.

—— juicy cushion of style, ii. 170.

—— pollen sprinkling, ii. 274.

—— scent, ii. 201.

Leuconostoc mesenteroides, fermentation,
ii. 623,

Leucopogon, pollen-tetrads, ii. 97.

Leucopogon Cunninghami, venation, i. 633.

Lianes, i. 364.

— adaptative modifications, i. 476.

— autumnal preparation for coming spring,
i. 282.

— general description, i. 670.

— hosts of Rhopalocnemis, i. 193.

— portion of stem, i. 689.

— ribbon-shaped, i. 475, 734.

— stem sections, i. 477.

— thickness of supports, i. 680.

— twisting of internodes, i. 417.

Libanotis montana, anthocyanin, i. 522.

— — elevation and coloration, ii. 511.

— — light and growth, ii. 508.

Libocedrus, winter colour, i. 485.

Libriform cells, nature of, i. 726.

Lichen, controlling element in, ii. 692.

—edible. See Lecanora esculenta.

— Graphic. See Lecidea geographica.

— modern views of nature, ii. 692.

Lichen-alga, determining growth in form of
Cora, ii. 695.

Lichen-fungus, growth independent of Alga,
ii, 695,

Lichen-thallus, ranging power of partners
of, i, 245.

Lichens, absorption of aqueous vapour, &.,
i. 218.

— absorption of carbonic acid, i. 62, 368.

— corrosion of iron, i. 258.

— Crustaceous, Istria and Dalmatia, heat

resistance, i. 554,

—— nature of, i. 244.

—dependenceon aoe 217.

— dispersal, ii, 693, 816.

dtia, geographical distribution, ii.

Lichens, dissemination of spores, i. 246,

— epiphytic, i. 77.

— — formerly treated as parasites, i, 159,

— etching of marble pillar by, i. 257.

— families of, ii. 693.

— Foliaceous, habit of, i. 244,

— force of hyphal threads, i. 513.

— forming rings, ii. 793.

— Fruticose, characteristics of, i, 245.

— gelatinous, i. 244; ii. 694.

— hyphe and Algas, ii, 693.

— on Loranthus, i. 212.

—part played by constituent members,
sensitiveness to environment, &c., i, 247.

— soredia, ii. 24,

—— dispersal, ii. 816,

— substratum, ii. 498.

— symbiotic nature, i. 244; ii. 682,

Life, cycle of, i. 264.

— discussion of origin, ii. 597.

— ever-interesting question of, i. 21.

Life-history of a Fern, ii. 476, '708.

Light, affects geographical distribution, i.
394.

—and anthocyanin, ii. 510.

— and form of leaves, i. 430.

— and direction of branching, i. 414.

—and habit of plants, ii. 504,

— and opening of flowers, ii. 219.

—and position of leaves, i. 409.

— and retardation of growth, ii. 407.

— and sexual organs of Vaucheria, ii. 644.

— avoiding tendrils, i. 699.

— bright, effect on chlorophyll, ii. 511.

— effect of varying intensity, i. 381.

— influence on formation of zoospores and
gametes, ii. 632.

— transformation into heat, i. 519.

Light-waves, length, i. 571.

Lignification, of hairs, i, 441,

— use of, i. 474,

Lignin, formation, i. 458.

Ligulate florets and nocturnal radiation, i.
530.

—— of Composite, ii. 114.

Ligule, function in arundinaceous plants, i. 98,

— of Grasses, i. 427; ii. 746.

— of Isoétes, ii. 716, 717.

— of Selaginella, ii. 715.

Ligustrum vulgare, dates of flowering, i. 519.

— — Witches’ Broom galls, ii. 548,

Lilac. See Syringa vulgaris.

Lilac scent, ii. 201.

Liliacez, dehiscence of pollen-sacs, ii. 93.

— geitonogamy in, ii. 325,

— general characters, ii. 730.

— incompletely protogynous genera, ii. 311.

— polyembryony in, ii. 468,

Liliflorezs, hybrids among, ii. 583.

— various, ii. 729.

Lilioidex, distinctive characters, ii. 731.

Lilium, pollen-grains, ii. 99,

— propagation, ii. 556.

Lilium album, bulb scales, i. 624,

—— cross-fertilization, ii. 301.

—— duration of flowering, ii. 213.

Lilium auratum, size of flowers, ii. 185.

Lilium bulbiferum, bulbils, ii. 461.

— — cross-fertilization, ii. 301.

— — heterogamy advantageous, ii. 578.

— — unfruitful artificial autogamy, ii. 406.

Lilium candidum, dates of flowering, i. 519.

— — flower-opening constant, i. 559.

— — protection of pollen, ii. 119.

Lilium Carniolicum, nectaries, ii. 176.

Lilium Chalcedonicum, nectaries, ii. 176.

Lilium croceum, absence of vegetative pro-
pagation, ii. 461.

Lilium Martagon, bulb scales, i. 624.

—— course of pollen-tubes, ii. 408.

—— downward pull of roots, i. 767.

— — leaf-movements, i. 339.

— — nectaries, ii. 176.

— — protogynous, ii. 311.

— — seed dispersal, ii. 447.

—-— stigma and germinating pollen-grains,

ii. 409.

INDEX,

Lilium Martagon, stomata, i. 339,

mer tigrinum, stamen of green flower, ii.

Lily-of-the-valley. See Convallaria majalis.

Lime. See Tilia.

Lime, accumulation by snails and hydro-
aia solution and reprecipitation, i.

— amount formed by Potamogeton lucens,
admixed mineral substances, i. 261.
Lime, bicarbonate, excretion by water-
absorbing organs, conversion into mono-
cabonate, i. 234.

— importance of, in nutrition, i. 67.

Lime incrustation, and preservation of fossil

plants, ii. 612.

—— in Chara, ii. 660.

—— in Codiacew, ii. 645.

—— of Hydrophytes, i, 61.

—— restrictive of transpiration, i. 313.

— oxalate of, i. 42.

— protective incrustation over absorption-
cells in Saxifraga Aizoon, &c., i. 234.

— protective incrustations on leaves, i. 235,

Limestone, corrosion by plants, i. 258.

— humus on, ii. 499.

— limits of vegetation, vertical, i. 527.

Limnanthemum, habit, i. 666.

— protective isolation by water, ii. 234.

Limnobium molle, habitat, as mud-collector,
i, 267.

Limosella aquatica,sub-aqueousfertilization,
ii, 391.

Linaria, estivation, ii. 211.

— and mode of entrance of insects, ii. 210.

— axillary buds, ii. 29.

— cleistogamy, ii. 393.

— honey concealment, ii. 180.

— insect platform, ii. 228,

— results of various crossings, ii. 560.

— sheltering of pollen, ii. 110.

— storing of honey, ii. 172.

— variability of floral colour, ii. 569.

Linaria alpina, flower, ii. 180.

Linaria cymbalaria, fading of flowers, i. 743.

— — flowering and seeding, i. 53.

Linaria gevistifolia, ii. 560.

Linaria littoralis and L. minor, behaviour to
own and foreign pollen, ii. 407.

Linaria Macedonica, capsule in dry and wet
weather, ii. 448.

Linaria pallida, radital buds, ii. 28.

Linaria striata and Linaria vulgaris, estab-
lished hybrid of, ii. 591.

Linaria stricta, established hybrid, ii. 591.

Linaria vulgaris, and animals, i. 432,

— — buds on hypocotyl, ii. 28.

—— radical buds, ii. 28,

Lindley, ii. 663.

Lindsaya, protection of sporangia, ii, 13.

Ling. See Calluna vulgaris.

Linnea borealis, cross-fertilization in, ii, 301.

— — flower, ii. 236.

—— scent, ii. 201.

—— sticky bracts, ii. 870.

Linnzus and hermaphrodite flowers, ii. 300.

— definition of a species, ii, 486.

— floral clock, ii, 215,

—on varieties, in Philosophia Botanica, ii.
514.

— (1707-1778), revolutionizes the study of
botany, i. 5.

— system of classification, i. 6; ii. 601.

Linnean system and Goethe, ii. 287.

— — classes 11, 12, 17, 21, ii. 293.

— — classes 13, 14, 15, 16, 18, 20, ii. 292.

— — first ten class, ii. 289.

—— table of classes, ii, 288.

Linum, heterostylism, ii. 399,

— seed cement, i. 615.

Linum catharticum, opening and closing, ii.
220.

Linum grandiflorum, withering of corolla
and pollination, ii. 286.

Linum perenne, opening of flower, ii. 212.

Linum tenuifolium, recurrent opening, ii.

213,

959

‘Linum usitatissimum, cluster-galls on, ii. 547,
— — non-adaptability, i. 393,
Linum viscosum, duration of flowering, ii.

— — guides to honey, ii, 249.
Liquidambar, pistillate flower, moncecia, ii.

—staminate flower, moncecia, ii. 293.

Liquorice. See Glycyrrhiza.

Liriodendron, fossil, i. 636.

— protection of pollen, ii, 124.

Liriodendron tulipifera, leaf-unfolding, i.

352.

—— pollen-grains, ii. 99.

— — protective stipules, i. 626.

— — stipules, i. 351.

Listera, insect-visitors, ii. 256.

— labellum, ii. 254,

Listera ovata, allurement of insects, ii. 206.

Lithium in plants, i. 68.

Lithophytes, i, 267,

— absorption of carbonic acid, i. 367.

— dust-catchers, i. 82.

— heat resistance, i. 554,

— rapid water surrender, i. 555.

— source of food salts, i. 79.

— what include, i. 56.

— whence obtain ammonia, i. 65.

— whence obtain carbonic acid, i. 61.

Lithospermum, protogynous, ii. 311.

Lithospermum arvense, autogamy, ii. 332.

— — protogynous, ii, 310.

Lithospermum purpureo-cceruleum, stolons,
i. 663.

Lithothamnes, lime deposition and resis-
tance, i. 425.

Lithothamnia, as marine lime-accumulators,
i, 261.

Littorella lacustris, offshoots, ii. 456.

— — resemblance to Isoétes lacustris, ii. 717.

Liverworts. See Hepatice.

Livia Juncorum, galls on Juncus, ii. 547.

Lizard Orchis. See Orchis hircina.

Loasacee, stinging hairs, i. 441.

Lobelia Dortmanni, resemblance to Isoétes
lacustris, ii. 717.

Lobelia splendens, scarlet flower, ii. 196.

Lobeliaceze, ii. 767.

Lobularia nummularia, autogamy, ii. 339.

Lobularia nummulariefolia, flowers and
young fruits, ii. 184.

Locust-bean, fruit of Ceratonia Siliqua, ii.
535.

Lodicule, of Gramines, ii. 746,

Lodoicea Sechellarum, fruit, ii. 452, 740.

Loew, E., Bliitenbiologische Floristik, ii.
399.

Loganiacee, ii. 771.

Loiseleuria, geographical distribution, i. 302.

— rolled leaves, i. 302.

Loiseleuria. See also Azalea procumbens.

Lonicera and Hawk-moths, ii. 207.

— and insect visits, ii. 223.

— cyme, i. 738.

— nectaries, ii. 177, 178.

— opening of flower, ii. 212.

— pollen-grain, ii. 100.

— twining stem, i. 681.

— twisting of internodes, i. 417.

Lonicera alpigena, flower-opening constant,

i. 559,

— — nectary, ii. 178.

—— pollen deposition, ii. 278.

Lonicera caprifolium, dextrorse twining, i.

—— nocturnal perfume, ii. 208.

— — opening of flower, ii. 211.

—— scent, ii. 201.

—— scent and Sphinx Convolvuli, ii. 208.

— — twining, i. 689.

Lonicera ciliosa, example of non-parasitic
creeper, i. 160.

Lonicera coerulea, cyme, i. 746.

— — reserve-buds, ii. 32,

Lonicera Etrusca, flower, ii. 227.

— — nocturnal perfume, ii. 208.

Lonicera fragrantissima, reseyve-buds, ii. 32.

960

Lonicera grata, ii. 177.

Lonicera implexa, ii. 177.

Lonicera nigra, honey protection, ii. 239.

Lonicera Periclymenum, autogamy, ii. 377.

—— nocturnal perfume, ii. 208.

— — twining, i. 689.

Lonicera Xylosteum, pollen deposition, ii.
278.

Lopezia, hammer-apparatus, ii. 263.
Lopezia coronata, stamen, ii. 263.

Lopezia racemosa, stamen, ii. 263.
Lophophytum, colouring of inflorescence, i.

— description, i. 194.
Lophophytum Leandri, superstitions about
tubers, i. 196,
Lophophytum mirabile, Brazil, i. 195.
—— tubers, native name, i. 196.
——— quack use of, &., i, 196.
Loranthacez, ii. 754.
— self-parasitism compared to grafting, i.
213.
Loranthus, and callus shoots, ii. 30.
— green cotyledons, i. 622.
— root, mode of growth, food-absorption, i.
212.
Loranthus buxifolius, parasitic on L. tetran-
drus, Chili, i. 213.
Loranthus Europzus, attachment to host, i.
209.
Loranthus Mutisii, flowers, i. 213.
Lotus, behaviour to own and foreign pollen,
2? 4k, 407.
— Indian, ii. 775.
7 — insect reception, ii, 228. “
_~ — leaf, diurnal positions, i. 534. i
— movements of cotyledons, i. 532. €
Lotus corniculatus and bud-galls of Cecido-
myia Loti, ii. 544.7
- —-— flower and pollen-pumping apparatus,
ii. 261.~
2 —— inflorescence, ii. 261. -
> —— bods, ii. 431. ~
— — tubercles on root-fibres, ii. 521.-
Lotus Lily. See Nelumbium speciosum.
Lousewort. See Pedicularis.
Lowlands, of North and Baltic Seas, plants
with rolled leaves on, i. 304.
Loxosoma, stomata, ii. 706.
Luminosity, advantage to Fungi, i. 504.
— cause of, in protonema of Schistostega, i.
386.
— in plants, i. 502.
— of Glow-worm, i. 386.
— of mycelium, i. 386.
— of Sea-weeds, i. 388.
Luminous Moss. See Schistostega osmun-
dacea.
Lunaria rediviva, seed-dispersal, ii. 852.
Lungwort. See Pulmonaria officinalis.
Lupinus, pollen expulsion, ii. 260.
Lupinus variabilis, tubercles on root-fibres,
ii, 521.
Luzula, ii. 730.
Luzula uivea, protogynous, ii. 311.
Luzula vernalis, pollen tetrads, ii. 97.
Lychnis alpina, autogamy, ii. 355.
Lychnis diurna, capsules in dry and wet
weather, ii. 448.
— — distribution of sexes, ii. 300.
— — duration of flowering, ii. 213,
— — imperfect flowers, ii. 295,
Lychnis flos-jovis, artificially induced droop-
ing, ii. 123.
Lychnis Viscaria, distribution of sexes, ii.
298.

— — elevation and coloration, ii. 511.
——gall-mites and flower metamorphosis,
ii, 548.

— — illumination and growth, ii. 508,

— — influence of gall-mites, ii, 550.

—— source of name, ii. 235.

Lycium, corolla and autogamy, ii. 366,

— honey protection, ii. 239,

— weaving stem, i. 672.

Lycium barbarum, corolla and autogamy, ii.
366,

INDEX,

Lycogala Epidendron, colour, i. 32.
— — fructification, ii. 618,
— — sporangia, ii. 491.
Lycoperdon, structure, i. 589.
Lycoperdon celatum, respiratory heat, i.
498.
Lycoperdon constellatum, ii. 690.
Lycoperdon giganteum, ii. 690.
Lycopodiacezx, as saprophytes, i. 100.
— root-tendrils, i. 694.
— structure, ii. 476.
Lycopodiales, ii. 716.
— description, ii. 713.
— sporophyte characters, ii. 704,
Lycopodium, alumina in, i. 68.
— bulbils dispersed by wind, ii. 817.
— life-history, ii. 714.
— phyllotaxis, i. 402. _
— prothallium, ii. 477.
Lycopodium alpinum, habitat, i. 112.
Lycopodium annotinum, prothallium and
young plant, ii. '716.
— — shoots, ii. 476.
Lycopodium cernuum, prothallium, ii. 714.
Lycopodium clavatum, leaf withsporangium,
ii. 716.
—— spore, ii. 716.
Lycopodium inundatum, difficulty of cultiva-
tion, i. 113.
Lycopodium Selago, Palzozoic, ii. 612.
— — plant with bud-like off-shoots, ii. 460.
Lycopods. See Lycopodiacee.
Lygodium, protection of sporangia, ii, 13.
— sporangia, ii. 709.
Lysi ciliata, ti
118.
Lysimachia nemorum, autogamy, ii. 341.
Lysimachia nummularia, and Phyllobium
dimorphum, ii. 638.
— — heterogamy, advantageous, ii. 578.
— — stolons, i. 663.
Lysimachia thyrsiflora, geitonogamy, ii. 326,
—— ovarian juicy warts, ii. 170.
—— protection of stomata from moisture,
i 294. |
Lythrales, ii. 784.
Lythrum Salicaria, heterostyly, ii. 303.
— — heterostyly and fertilization, ii. 405.

of pollen, ii.

M.

Macaw Tree. See Acrocomia sclerocarpa.

Mace, of Nutmeg, ii. 425.

Macfarlane and Cytisus Adami, ii. 571.

Maclura aurantiaca, radical shoots, ii. 27.

Macrocystis, size, ii. 598.

— thallus differentiation, ii. 662.

Macrocystis pyrifera, geographical range, i.
388,

—— size, i, 388,

Macropodous embryo, ii. 738.

Macrosporangia, of Isoétes, ii. 717.

— of Marsilia, ii. 711.

— of Pilularia, ii. 711.

— of Salvinia, ii. 711.

— of Selaginella, ii. 715.

Macrospore, of Azolla, ii. 711.

— of Hydropterides, ii. 710.

— of Pteridophyta, ii. 704.

— of Selaginella, ii. 477.

Macrozamia, Australia, ii. 720.

Madder. See Rubia.

Magnesium, in ash of plants, i. 66,

Magnesium chloride, in salt incrustations, i,

236.

—— in sap of succulents, i. 329,

Magnesium sulphate, in salt incrustations of
leaves, i, 236.

Magnolia, insects and pollen, ii. 244.

— stipules, i. 351.

Magnolia Campbellii, Sikkim, size of flowers,
ii. 185.

Magnolia obovata, abode for Beetles, ii. 163,

Magnolia Yulan, scent, ii. 203,

Magnoliacesx, anther, ii. 90.

Mahaleb. See Prunus Mahaleb.

Mahogany-tree. See Swietenia Mahogoni.

Mahonia, anthocyanin, i.

— protection of pollen, ii. 119.

Maianthemum bifolium, venation, i. 633.

Maize. See Zea Mais.

Malachium aquaticum, autogamy, ii. 338.

Malaxis monophyllos, epipbyllous buds, ii. 43.

Malaxis paludosa, brood-body and ovule, ii.
84.

— — buds on leaves, ii. 41.
Malcolmia Africana, guides to honey, ii. 248.
Malcolmia maritima, flower, ii. 249.
Male-fern. See Aspidium Filix-mas.
Malic acid,‘i. 463.
—~— in Nepenthes pitcher, i. 135.
Malpighiacee, cleistogamy in, ii. 393.
Malt, nature of, i. 497.
Malva, dehiscence of pollen-sacs, ii. 92.
— hybridism in, ii. 584.
— schizocarp, ii. 430.
Malva borealis, antogamy, ii. 355.
Malva rotundifolia, autogamy, ii. 355.
— — pollen-grains, ii. 99.
Malvacezx, autogany in, ii. 352.
— course of pollen-tubes, ii. 410.
— insect platform, ii. 230.
— pollen-grains, ii. 100.
— protandrous, ii. 312.
— stigmatic surface in, ii. 281.
— stomatal protective hairs, i. 292.
Malvales, ii. 776,
Mammillaria, autogamy, ii. 347.
— cross-fertilization, ii. 301.
— nectary concealment, ii. 181.
— offshoots dispersed by animals, ii. 829.
— protection of pollen, ii. 113.
Mammuillaria glochidiata, flower, ii. 174.
—— withering of corolla and pollination, ii.
286.
Mammillaria pectinata, whole plant, ii.'787.
Mammoth Tree. See Sequoia gigantea.
Man, protection of plants, i. 431.
Mandragora, cross-fertilization, ii. 305.
— pollen deposition, ii. 278.
— scent, ii. 202.
Mandragora (Atropa) officinalis, leaves and
rain conduction, i. 95.
Mandragora vernalis, protection of pollen,
ii, 128.
— — stages in blossoming, ii. 279.
Manganese, in plants, i. 68.
Mangrove. See Rhizophora,
Mangrove-forest, ii, 891.
Mangroves, columnar roots, i. 759.
— elevation by roots, i. 771.
— no root-cap in marsh-inhabiting, i. 164.
Manna, a Lichen, ii. 810.
Mannite, alluring, i. 461.
— from sugar, i. 506.
Mantisia saltatoria, flower, ii. 736.
Mantle-galls, ii. 528,
Manubrium of Chara fragilis, ii. 660.
Mauure, application of artificial, i. 75.
— of Rotifers, beneticial to certain Liverworts,
i, 255.
Maple. See Acer.
— Red. See Acer rubrum.
Maranta, venation, i. 634.
— yields arrow-root, ii. 736.
Marantacee, floral characters, ii. 736.
Marasmius, sole habitat of certain species,
i, 118.
Marasmius tenerrimus, ii, 21, 685.
Marattiaces, abundance of Paleozoic forms,
ii. 709,
— characteristics, ii, 709.
Marcgravie, appearance on trunks, i. 108.
— vegetative propagation, ii. 800.
Marcgravia umbellata, transitional habit, i.
708,
Marchantia, absorption-cells, i. 86.
— offshoots dispersed by rain, ii, 809,
Marchantia polymorpha, air-chamber and
stomate-like pore, ii. 697.
— — thallidia, ii. 23.
— — transpiring cells, i, 278.

Marchantiaces, desoription, ii. 697.

Marine vegetation, limits, i, 387.

Marjoram, seeds and heat, i. 555.

Marrubium, distribution of sexes, ii. 298,

— hairiness, i, 317,

— hybrids, ii, 585.

Marrubium remotum, hybrid, ii. 563, 585.

Marrubium vulgare, hooked fruit, ii, 873.

Marsh Andromeda. See Andromeda poli-
Folia,

Marsh Cinquefoil. See Comarum palustre.

Marsh Crane’s-bill. See Geranium palustre.

Marsh gas, i. 453.

Marsh-plants, ‘adaptation to environment, i.

425.

— — floating contrivances, i. 638.

— — food-absorption, i, 75,

—— roots, i. 752.

Marsilia, leaves and sporocarps, ii. 711.

Marsilia quadrifolia, ii. 740.

— — leaf-movements, i. 339.

—— stomata, i. 339.

Martagon Lily. See Lilium Martagon.

Martynia, closing of stigma, ii, 281.

Masdevallia, ii, 738,

Mastic Tree. See Pistacia Lentiscus.

Mastichonema, filaments, i. 586.

— symbiotic nature and habitat, i. 248.

Maternal stock, in hybridization, ii. 557,

Mat-grass, See Nardus stricta.

Matricaria, geitonogamy, ii. 322.

Matricaria chamomilla, pericarp mucilage,

i, 615, j

— — pollination and rachis, i. 740.

Matter, decaying, in relation to life, i, 104.

— living, hypotheses of formation, ii. 597.

Matthiola annua, nectaries, ii. 174.

—— possible cause of doubling, ii. 554.

— — scent, ii. 201,

Matthiola bicornis, fruit protection, ii. 442.

Matthiola incana, possible cause of doubling,
ii. 554,

Matthiola tricuspidata, fruit protection, ii.
442, 445.

Matthiola varia, scent, ii. 201.

May, ‘ Hisminner”, i. 539,

— fall of temperature in, i. 539.

May Lily. See Maianthemum bifolium.

Meadow-grass. See Poa.

Meadow-rues. See Thalictrum.

Meadow-safiron. See Colchicum autumnale.

Meadows of Central Alps and herbage, i. 451.

Mechanical cells, nature of, i. 725.

Mechanical changes effected by plants in the
ground, i, 265,

Mechanical force, of growing organs, i. 514.

— — of roots, ii. 515.

Mechanical tissue, “distribution of, i. 729,
730, 731.

Mechanism, transition from water absorbing
to prey absorbing, i. 157.

Mechani for convey

siderations, i, 467.

— for prc i i
ii, 232,

— of removal, sorts of, i. 468,

— strengthening, i. 474.

Medeola asparagoides, extra-axillary buds,
ii, 28,

,» general con-

it unw

guests,

Medicago, explosive flowers, ii. 267.

— hybrid flower colour, ii. 567.

— leaf, diurnal positions, i. 534.

Medicago agrestis, hooked fruit, ii. 873.

Medicago falcata and M. sativa, colour of
flowers and hybrid, ii. 567.

——and M. sativa, hybrid, increased fer-
tility of, ii. 579.

Medicago media, hybrid, colour of flowers,
ii, 567.

—— hybrid, increase of fertility, ii. 579.

Medicago radiata, hooked fruit, ii. 873.

Medicago scutellata, wind dispersal, ii. 848.

Mediterranean flora, species with varnish-

like coating on leaves, i. 312.

— plants with evergreen rolled leaves, i, 306.

— Thistles, i, 438.

Medinilla, stamen, ii. 91.
Vou. II.

INDEX.

Medlar. See Mespilus Germanica.
Medulla, i. 469.

Medullary rays, i. 468.

— sheath, i. 469.

ae a laciniata, seed-dispersal, ii.

Megamete, of Chlamydomonas, ii. 630,

— of Phyllobium, ii. 638.

Melaleuca, flower, ii. 292, 782.

— hermaphrodite, ii. 296.

— inflorescence, i. 738.

— silky bark, i. 720,

— unprotected pollen, ii. 107,

— vertical leaf-blades, i. 336.

Melampsora Gceppertiana and Vaccinium
Vitis-Idesa, ii, 525.

Melampsora populina, on Populus leaves, i.
256.

Melampyrum, parasitic, seedling, i. 176,

— protection of pollen from wet, ii. 110.

Melampyrum arvense, colour-contrast in
flower, ii. 191.

Melampyrum cristatum, bract colour, and
locality, ii. 194.

Melampyrum grandiflorum, colour-contrast
in flower, ii. 191.

Melampyrum nemorosum, colour-contrast in
flower, ii. 191.

Melampyrum pratense, autogamy, ii. 253,

Melampyrum sylvaticum, autogamy, ii. 377.

Melanium, tribe of Violacez, ii. 386.

Melanoxylon decipiens, phyllode, i. 335.

Melastoma Malabathricum, ii. 783.

Melastomacez, explosive flowers, ii. 267.

— pollen-sprinkling in, ii. 274.

— soft bast, i. 469. ‘

— uniformity of venation, i. 635.

Melastomales, ii. 783.

Melianthus, odour of floral secretion, ii. 171.

— scent, ii. 200.

— storing of honey, ii. 172.

— Sun-birds and pollen, ii. 247.

— waxy coating, ii. 237.

Melianthus major, flower, ii. 227.

—— flower and Sun-birds, ii. 225.

Melica, pollination, ii. 142.

Melica altissima, arched leaf, i. 429,

—— dichogamy, ii. 312.

— — seed-dispersal, ii. 854.

Melica Balansz, plumed glumes, ii. 858.

Melic-grass. See Metlica.

Meligethes eeneus, sheltering in Composite,
ii, 163.

Melilotus, insects and keel-movements, ii.

— leaf, diurnal positions, i. 534.

Meliola, tropical Mildew, ii. 677.

Melissa officinalis, stamen, ii. 91.

Melittis, cotyledons, i. 608.

— variability of floral colour, ii. 569.

Melliferous flowers, protection of nectar, ii.
128.

Melocactus, and Wild Asses, i. 447.

— spines, i, 446.

Melon and cold, i. 545.

— seeds and heat, i. 555.

Melon-pumpkin. See Cucurbita maxima.

Members, protected by spines, i. 433.

Membranous bark, i. 720.

—scales, of Ferns, i. 355.

Menispermacew, leaf-stalk bundles, i. 649.

— liane-like, i. 670.

Menispermum Carolini
bundles, i. 649.

—— stem, i. 364.

Mentha, distribution of sexes, ii. 298.

— hybrids, numerous, ii. 588.

Mentha alpigena, forms rings, ii. 793.

Mentha sylvestris, spikes and radiation, i. 530.

Menyanthes, autogamy, ii. 396.

— dehiscence of pollen-sacs, ii. 93.

Menyanthes trifoliata, creeping stem, i. 662.

— — heterostyly, ii. 302.

— — protogynous, ii. 310, 311.

— — weather and self- and cross-pollination,

ii, 391.
Menziesia, pollen tetzads, ii. 97.

leaf-stalk

‘| — heterostyly, ii. 302.

961
Mercurialis, dicecious, ii. 300. &
Mercurialis annua, parthenogenesis, ii. 465.
Mercurialis perennis, downward pull of

roots, i. 767.

— — mixing of pollen, ii. 403.
Mericarp, nature of, ii. 430.
— of Erodium, hygrometer, ii. 619.
Merismopedia, habitat, ii. 621.
Meristem, diversity of products, i. 583.
— nature and activity, i. 582.
Mertensia, autogamy, ii. 396.

x
— protection of pollen, ii. 118. =)
Mertensia maritima, Arctic, absence of
hairs, i. 316.
Mertensia Sibirica, floral change of colour,
ii, 191,
Merulius lacrymans, i. 263.
— — hymenium, &c., ii, 688,
— — mode of growth, ii. 790.
Mesembryanthemum, protection of pollen,
ii. 113,
Mesembryanthemum annuum, seed-disper-
sal, ii, 845.
Mesembryanthemum Candolleanum, seed-
dispersal, ii. 845.
Mesembryanthemum crystallinum, colour-
contrast of flower, ii. 189.
— — resistance to drought, i. 329.
Mesembryanthemum foliosum, aqueous tis-
sue, i. 328.
Mesocarpus, chlorophyll plate, i. 373.
— conjugation, ii. 658.
Mesomycetes, distinctive characters, ii. 674.
Mesophyll, transpiring leaf-tissue, i. 278.
Metabolism, nature of, i. 455,
— variety and constancy of products, i. 491.
Metamorphosis, and division of labour, i. 594.
— doctrine of, gives origin to scientific study
of development, i. 13.
— Goethe’s explanation, i. 10.
— of flowers, due to gall-mites, ii. 548.
— of leaf, contractions and expansions, i. 12.
— views of Linnean school, i. 9.
Meteoric dust, nature of, i. 80.
Metrosideros, coloured stamen-filaments, ii.
183,
— inflorescence, i. 738.
— unprotected pollen, ii. 107,
— venation, i. 630.
Metzgeria, apical-cell, i. 578. '
Meum, geitonogamy, ii. 324.
Meum Mutellina, hermaphrodite and pseudo-
hermaphrodite male flowers, ii. 296.
—— scent, ii. 202,
Mexican Cedar. See Taxodium Mexicanum.
Mexico, hairiness of plants, i. 317,
— high plains, Cacti, i. 327.
— spiny plants, i. 438,
Mezereon. See Daphne Mezereum.
Miasmas, cause of, i. 506.
Mica, difficult to decompose, i. 83.
Micellz, groups of molecules, i. 57.
— of cellulose, in cell-plate, i. 581.
Micrasterias morsa, ii. 492, 655.
Micrasterias papillifera, ii. 492, 655.
Micrococcus aceti, fermentation, ii. 623.
Micrococcus diphthericus, disease gérm of
diphtheria, i. 163,
Micrococcus prodigiosus, ii. 624,
— — “blood-portent”, ii. 623,
Microcystis ichthyloba, home of, i. 105.
Mier te, of Chlamyd ii, 630.
— of Phyllobium, ii. 638.
Micromeria Kerneri, probable hybrid, ii. 592.
Micromeria nervosa, plumed fruits, ii. 857.
Micropus, distribution of sexes, ii, 297.
Micropylar caruncle, ii. 425.
— scar, ii. 425.
Micropyle, of ovule, ii. 81.
—— and pollen-tube, ii. 410.
— position in Abietines, ii. 438.
— position in Cupressinez, ii. 439.
Microscope, effect on ptudy of botany, i. 7.
— first discoveries, i. 21.
— limits of magnification, i. 571.
Microsomata, in cell division, i. 581.
lil

962

Microsomata in Desmidiez, i. 35.

— of protoplasm, i. 33, 569.

Microsporangia, of Azolla, ii. 711.

— of Hydropterides, ii. 710.

— of Isoétes, ii. 717.

— of Marsilia, ii, 711.

— of Pilularia, ii. 711.

— of Pteridophyta, ii. 704.

— of Rhizocarpezx and Selaginellez, ii. 69.

— of Selaginella, ii. 477.

— of Selaginella, germination, ii. 715.

Microspores of Azolla, ii. 711.

Midges in Aristolochia Clematitis flower, ii.
226.

Midrib tendril, i. 692.

“Milchdieb”, German name for Euphrasia,
i. 179.

Mildew, hyphe of, i. 165.

Mildews. See Erysiphee.

Milfoil. See Achillea.

Milium effusum, arched leaf, i. 429.

Milk, effect of Pinguicula ferment on, i. 143,

— of Almonds, i. 458.

— souring, i. 506.

‘*Milk-thief ”, name for Euphrasia, i. 179.

Millet. See Panicum.

— starch, i. 459.

Miltonia stellata, fruit, ii. 73.

Mimosa, pulvini, i. 308. *

Mimosa hispidula, fruit prot ii. 443.

INDEX.

Monochlamydex, of Bentham and Hooker,
ii. 604.

— of De Candolle, ii. 603.

Monocotyledones, distinctive characters, ii.
728.

Monocotyledones, of de Jussieu, ii. 602.

Monocotyledons, of Bentham and Hooker,
number of orders, ii. 604.

Moncecious plant, type, ii. 298.

Moncecious plants and hybridization, ii. 315.

— — protogynous, ii. 313,

Monoepigyne, of de Jussieu, ii. 602.

Monoperigynz, of de Jussieu, ii. 602.

Monopetala, floral characteristics, ii. 748,

— of de Jussieu, ii. 602.

Monostroma, thallus, ii. 648.

Monotropa, anthocyanin, i. 483,

— colour and surroundings, ii. 195.

— embryo, i. 596.

— embryo-sac, ii. 417.

— honey protection, ii. 241.

— life-history, ii. 253,

— nectaries, ii. 178.

— pollen-sacs, ii. 89.

Monotropacex, ii. 768.

Monstera egregia, Brazil, leaf, i, 413.

Monsterex, climbing habit, ii. 745.

Monstrous flowers, ii. 80.

Mont Blane, insolation, i. 525.

Mor equitant leaves, i. 336.

Mimosa Lindheimeri, leaf, day and night
positions, i. 533.
Mimosa polycarpa, fruit protection, ii, 443.
Mimosa pudica, day and night positions, i.
7.

— — fruit protection, ii. 443.

— — liberation of cotyledons, i. 612.

Mimosa sensitiva, and rain, i. 537.

Mimosez, Brazilian, spines, i. 444.

— leaf movements, i. 338, 339.

— movements of cotyledons, i. 532.

— pollen-sacs, ii. 90.

— position of stomata on leaves, i. 281.

— sensitiveness, i. 535.

Mimulus, dehiscence of pollen-sacs, ii. 93.

— movements of cotyledons, i. 532.

Mimulus luteus, closing of stigma, ii. 281.

— — flower and pollination, ii. 280.

Mimulus moschatus, pollen-grains, ii. 98.

Mineral constituents of soil, soluti dis-
placement, accumulation of, i. 257.

— salts, réle of, i. 510.

Mineralization, by Bacteria, simple illustra-
tive experiment, i. 265.

Minerals, retention by humus, ii. 499.

Mirabilis, movements of cotyledons, i, 532.

Mirabilis Jalapa, autogamy, ii. 357.

— — opening of flower, ii. 212.

— — pollen-grains, ii. 97.

— — protogynous, ii. 310.

— — stamen, ii. 87.

Mirabilis longiflora, flower and visitors, ii.

225.

— — opening and closing, ii. 212.

—— pollen-grains, ii. 97.

Mischococcus, life-cycle, ii. 636.

Mistletoe, the European. See Viscum album.

Mnium, phyllotaxis, i. 408.

Mock Orange. See Philadelphus.

Mohl, applies term protoplasm, i. 25,

Moisture, seed protection against, ii. 447.

Molecules, arrangement of, i. 567.

— forces affecting union of, i. 58,

— groups of atoms, i, 57.

— of albumen, i. 457.

— size, i, 571.

Molinia coerulea, mechanical tissue arrange-
ment, i. 730.

Moller, observations on Cora, ii. 695,

Molluscs, on Mangrove roots, i. 756.

Monandrse, floral characteristics, ii. 736.

Monarda fistulosa, colour and bees, ii. 195.

— — seed-dispersal, ti. 841.

Monkey Flower. See Mimulus,

Monkey-ladder. See Caulotretus.

Monochlamydesg, ii. 617.

— description, ii, 748.

Montia fontana, weather and autogamy, ii.
391.

Moonwort. See Botrychium.

Moor-grass, Thin-leaved. See Sesleria tenui-
Solia.

Moracew, ii. 758.

Morchella, asci and ascospores, ii. 19.

— structure, i. 589.

Morchella esculenta, ii. 19, 683.

—— receptacle, ii. 683.

Morel. See Morchella esculenta.

Morina, autogamy, ii. 352.

Morina Persica, autogamy, ii. 352.

— — behaviour of flowers after fertilization,

ii, 222,

— — flower and autogamy, ii. 351.

— — pollen-grains, ii. 98.

—— pollinated stigma, ii. 351.

— — time open, ii. 213.

Morphine, i. 462.

Morphology, comparative, aim of, i. 15,

Mortierellez, distinctive characters, ii, 674.

Morus, collective fruit, ii. 436,

— discharge of pollen, ii. 94.

— fruit, ii, 433.

— persistent perianth, ii. 750.

— pollination, ii. 133.

Morus nigra, normal and sucker leaves, ii. 515.

— — notched leaves, i. 413.

Mosaics, of leaves, i. 410.

Moschatel. See Adoxa Moschatellina,

Moss, analogy of protonema with pro-embryo
of Chara, ii. 660.

— germinating spore, ii. 477.

Moss Campion. See Silene acaulis.

Moss-capsule, structure, ii. 702.

Moss cushions, favourable site for germina-
tion of seeds, i. 266.

Moss-leaves, folding of, i. 346.

Moss-plant, ii, 477.

Moss-protonema, ii. 701.

—— and bud, ii. 477.

as absorption of carbonic acid, i. '62,

— absorption of water, mechanism of absorp-
tion, i. 218,

— alternation of generations, ii. 477, 4'79.

— apical-cell, i. 579,

—certain, give rise to a calcareous tufa in
streams, i. 260.

— climate and distribution, ii. 457,

— ee action, similarto thatof Lichens,
. 258,

— epiphytic, i, 77.

— — formerly treated as parasites, i. 156.

— fastidious, i. 118.

—- fertilization under water, ii. 71.

Mosses, formation of brood-bodies, ii. 25.

— forming rings, ii. 794.

— fossil, occurrence, ii. 704.

— general description, ii, 699.

— habitat and greenness, i. 387.

— hybrids among, ii. 583.

— in cascades, i. 79.

— leaf characters, ii. 702.

— lithophytic early stages, i. 82.

— not eaten by animals, i. 432.

— origin of sporophyte, ii. 654.

— parthenogenesis in, ii. 464.

— pressure exerted by rhizoids, i. 514.

— propagation by thallidia on Elvend Kuh,
ii. 457.

— rarely attacked by parasitic Fungi, i. 168.

— reproductive organs, ii. 701.

— saprophytic, i. 100, 103.

— sexual organs, ii. 478.

— spore-capsules, ii. 703.

— spore-dispersal, ii. 813, 814.

— sporogonium, ii. 473.

— various, ii. 700.

Moth Mullein. See Verbascum Blattaria.

Mother-plant, in hybridization, ii. 557.

Moths, night-flying, characteristics of floral

hosts, ii. 225.

M i h istic:

Moulds, and disease, i. 507.

— as agents in putrefaction, i. 263.

— description, ii. 677.

— fermentative, i. 505, 508.

— in amber, ii. 614,

— mode of attack, i. 163.

Mountain Ash. See Sorbus Aucuparia.

Mountain Pines, Tyrol, i. 549.

Mouse-ear Hawkweed. See Hieracium Pilo-
sella,

Movement, in relation to animals and plants,
i, 21

— of Diatoms, ii. 626.

— of sap, i. 362.

Movements, autonomous, ii. 221.

— of Chlamydomonas, and light, ii. 629.

— of chlorophyll-granules, i. 380.

— of cotyledons, i. 520 et seq.

— of Desmids, ii. 656.

— of flowers and loss of heat, i. 530.

— — and protection of pollen, ii. 120.

— of leaves, i. 532.

— of plants and sunlight, i. 380.

—of protoplasm and chlorophyll-granules,
i. 382.

— of roots, i. 772.

— of style, ii. 277.

— periodic, and growth, ii. 220.

—— puzzling nature, ii. 221.

Mucilage, i. 312.

— and fertilization, ii. 64.

— from cellulose, i. 458.

— from Pinguicula glands, i. 141.

— water retention, i. 329.

Mucor, fermentative action, i. 508.

— self-parasitism, ii. 674,

Mucor Mucedo, life-history, ii. 673.

— — sporangia and fruit-formation, ii. 18.

Mucor racemosus, respiration and fermenta-
tion, i. 509.

Mucor tenuis, conjugating branches, ii. 673.

Mucoraces, saprophytic and parasitic, ii. 674,

Mucorini, asexual and sexual reproduction,
ii. 481.

— fertilization and fruit-formation, ii. 53.

— parthenogenesis in, ii. 464.

Mucuna pruriens, fruit-protection and dis-
persal, ii. 444.

Mud, and preservation of fossil plants, ii, 612.

Mulberry. See Morus and Broussonetia.

Mulgedium, geitonogamy, ii. 319.

Mullein, Great. See Verbascum Thapsus.

Mullein tea, preparation of, i. 443.

Muller, Hermann, views on insect fertiliza-
tion in Alps, ii. 400.

Multicellular structures, formation, i. 576,

Musa, venation, i. 634.

Musa paradisiaca, ii. 734,

Musa sapientum, ii. 734,

ii, 658.

Muscardine, disease of Silk-worms, i. 168,

Muscari, neuter flowers, ii. 295,

Muscari comosum, raceme, ii. 184.

Muscari racemosum, bulbs, ii. 796.

Muscari tenuifolia, sterile flowers, ii. 187.

Musci, See Mosses,

Muscinex, archegonium, ii, 64.

— fertilization, ii. 65.

—— sporogenous generation, ii, 15.

— sporogonia, spore-formation, &c., ii. 16,

Mushroom, basidia, ii. 20.

— force of growth, i. 514.

Mushroom-spawn, a mycelium, i. 100.

Musk Orchis. See Herminiwm Monorchis.

Mutilation, effect on floral region, ii. 517.

— influence on plants, ii. 515.

Mutisia decurrens, tendrils, i. 692.

Mutisia hastata, tendrils, i. 692.

Mutisia subspinosa, tendrils, i. 692.

Mycelia, effects not always visible externally,
&e,, i, 165.

— fermentative action, i. 508.

— fossil remains, ii, 614.

— in salt-mine, i. 101.

-— in wooden pipes, i. 117,

— luminosity, i. 386, 502.

— mode of growth, ii. 790.

-- reticular, i. 586.

Mycelial mantle of Populus and Fagus roots,
i. 250.

Mycetozoa. See Myxomycetes.

Mycoidea, life-cycle, ii. 653.

Mycoidea parasitica, hosts, ii. 653.

Mycoideacex, reproductive bodies, ii. 653.

Mycomycetes, distinctive characters, ii, 676.

Mycorhiza Fungus of Pinus, ii. 678.

Mycosis, nature of, ii. 678.

Mycropyle, of ovule, i. 644.

Myoporacez, ii, 771.

Myosotis, colour-contrast in flower, ii, 190.

— cotyledon bristles, i. 623,

— galls of Synchitriun, ii. 520.

— heterostyly, ii. 302.

— venation, i. 630.

Myosotis alpestris, pollen-grains, ii. 97.

—— scent, ii. 202.

Myosotis palustris, venation, i. 631.

Myosotis sylvatica, autogamy, ii. 378,

—— re-erection of inflorescence, i. 744.

Myosurus minimus, ii. 773.

—— receptacle and carpels, ii. ‘73.

Myrica, porogamic fertilization, ii. 413.

Myriophyllum, as lime accumulator, i. 260.

— moneecious, ii. 297.

— protogynous, ii. 313.

Myriophyllum spicatum, stem section, i. '735.

Myristica moschata, seed and aril, ii, 425,

Myristicacex, aril in, ii. 425.

Myrmecophilous plants, ii. 233.

Myrrhis, how protected, i. 451.

Myrsinacez, ii. 770.

Myrtacez, ii. 781.

— coloured bracts in, ii. 183.

— coloured stamen-filaments in, ii. 183.

— position of leaf-blades in many, i. 335.

— uniformity of venation, i. 635.

— variety of foliage, ii. 471.

— venation, i. 630.

Mpyrtales, Australian, inflorescence, i. 738.

Myrtles, Australian, wax on leaves, &c., i.
292.

Myrtus, staminal insect platform, ii. 230.
Myxameebe, nature and behaviour, ii. 619.
Myxomycetes, absence of cellulose, i. 573.
— animal affinities, ii. 607.

— calcium oxalate crystals in, i. 570.

— description, ii. 618.

— formative activity of protoplasm, i, 572.
— fossil, ii. 619.

— nature of plasmodium, i, 585.

— sporangia, ii. 491.

— structure of external coating, i. 569,
Myzus ribis, gall on Ribes rubrum, ii, 531.

INDEX,

N.

Naiadacen, i, 424,

Naias, food-absorption, i. 765.

— pollen and pollination, ii. 105,

— spiny leaves, i. 438,

Narcissus, ii. 734,

— autogamy, ii, 332.

— germination, i. 604,

— leaf twist, i. 429,

— pollen-grains, ii. 99,

Narcissus juncifolius, autogamy, ii. 378.

Narcissus poeticus, colour-contrast in flower,

ii, 190.

— — dehiscence of pollen-sacs, ii. 93,

— — flowers and visitors, ii, 225.

— — protogynous, if, 311,

— — stigma, ii. 279.

Narcissus Pseudonarcissus, flower, ii. 177.

Nardosmia fragrans, scent, ii. 201.

Nardosmia frigida, offshoot formation, ii.
453.

Nardus, pollination, ii. 142.

Nardus stricta, absorption cells, i, 114,

—— and cattle, i. 436.

Narthecium, ii. 730,

— autogamy, ii. 334,

— equitant leaves, i. 336.

Nasturtium officinale, epiphyllous buds, ii.
43,

Nasturtium palustre, and galls of Cecidomyia
Sisymbrii, ii. 545,

Nasturtium sylvestre, and galls of Cecido-
myia Sisymbrii, ii. 544.

Natural selection, theory of, ii. 600.

Natural system, of classification, ii, 602.

Nature Philosophers, speculations about
Balanophorez, i. 190.

Nature-philosophy, of Oken and others,
i, 13,

Navicula, cold resistance, i, 542.

Navicula Liber, ii. 626.

Navicula tumida, ii. 626. :

Neckera Besseri, parthenogenesis, ii, 464,

Nectaries and position of anthers, ii. 95.

— in Ranunculace, ii. 250.

— morphological divisions, ii. 179.

— of flowers, ii, 174.

Nectariferous scale, of Parnassia, ii. 249.

Nectarinie, characteristics of floral hosts, ii.
225.

Nectarless alluring contrivances, ii. 167 et
seq.

— flowers, ii. 167.

Nectary, morphology, ii. 175,

— stipular, ii, 232.

Nectria cinnabarina, hosts, &., ii. 678,

Nelumbium, embryo, ii. 450.

— venation, i. 632.

Nelumbium luteum, size of flowers, ii, 185,

Nelumbium speciosum, ii. 439, 775.

— — flower, ii. 440.

—— size of flowers, ii. 185.

Nemato-cecidia, thread-worm galls, ii. 528.

Nematodes, gall production, ii. 528.

Nemanthus Guilleminianus, scarlet flower,
ii. 196,

Nematus gallarum, gall, ii. 533, 552.

Nematus medullaris, canker cushions on
Salix, ii. 543.

Nematus pedunculi, differences in galls, ii.

553.

—— gall on Salix incana leaf, ii. 531.
Nematus vesicator, gall, ii, 533, 552.
Neomeris, structure, ii. 647.

Neottia, colour and surroundings, ii. 195,
Neottia Nidus-avis, ii. 737.

——— absorption-root, i. 115.

—— — description, i. 111.

—— — radical buds, ii. 28,

Neottiex, characteristic genera, ii. 737.
Nepenthes, genera, i. 132.

— habitat, i. 132.

— leaves, 1. 132.

— pitcher-plants, narrow sense, i. 130.

963

Nepenthes, pitchers, i. 132!

—— size, i, 134,

— seedling, i. 132,

— tendrils, i, 692.

Nepenthes albo-marginata, pitcher, i. 134,

Nepenthes ampullaria, pitcher, i. 134,

— — shape of lamina, i. 123,

Nepenthes destillatoria, i. 133.

Nepenthes echinostoma, pitcher teeth, i.
134,

Nepenthes hybrida, fringe of spines at orifice
of pitcher, i. 124.

Nepenthes Mastersiana, hybrid and colour
of pitchers, ii. 567.

Nepenthes Rafflesiana, pitcher teeth, i. 134.

Nepenthes Rajah, pitcher, i, 134,

Nepenthes sanguinea and N. Kharsiana,
colour of pitchers and hybrid, ii. 567,

Nepenthes Veitchii, pitcher teeth, i. 134.

Nepenthes villosa, pitcher, i. 127.

— — teeth of pitcher, i. 136.

Nepenthes vitata, shape of lamina, i. 123.

Nepeta Pannonica and galls of Aulax, ii.
537. ,

Nepeta reticulata, coloured bracts, ii, 183.
Nephrodium, spore-dispersal, ii. 825.
Nephrodium Filix-mas, membranous scales,
i, 355.
—-—-— stomata, surface view and section,
i, 294.
Nephrolepis Duff, ii. '707.
— — fronds, ii. 11.
Ner tis, thallus diff jon, ii, 663.
Nerium Oleander, branching, i. 749.
—— epidermis, i. 369,
— — food of Sphinx Nerii, ii. 488.
— — habitat, i. 296.
— — laticiferous tubes, i. 470.
—— leaf, section, i. 310.
— — phyllotaxis, i. 397.
—-— protection of stomata from wetting,
i, 296,
— — seed hairs, ii. 424,
Neroli, from Orange flowers, i. 461,
— oil of, ii, 203,
Nerve, of leaf, i. 628,
Nerve-parenchyma, i. 468,
Neslia paniculata, seed fixation, i. 616,
Nettle-leaved Bell-flower. See Campanula
Trachelium.
Nettles, stinging hairs, i. 441.
Nettle-tree. See Celtis australis.
Net-work, of protoplasm, i. 511.
Neuroterus fumipennis, gall, ii. 552.
— — galls on Oak-leaves, ii. 537.
——spangle leaf-gall on Quercus Cerris, ii.
541,

Neuroterus lanuginosus, galls, ii. 552,

— — galls on leaves of Turkey Oak, ii. 537.

—-— spangle leaf-gall on Quercus Cerris, ii.

541.

Neuroterus numismatis, gall, ii. 552.

— — galls on Oak-leaves, ii. 537.

—— spangle leaf-gall on Quercus Cerris, ii.

541.

Neuroterus Schlectendali, staminal galls on
Quercus Cerris, ii. 540.

Neuter flowers, ii. 294,

Neuwiedia, stamens, ii, 736.

New World, hairiness of plants on savan-
nahs and prairies, i. 317.

New Zealand Flax. See Phormium tenax.

Nicandra, autogamy, ii. 346,

— nectary concealment, ii. 181.

Nicandra physaloides, rapid fertilization, ii.
285.

Nicotiana and cold, i. 545.

— corolla and autogamy, ii. 366,

Nicotiana affivis, night visitors, ii. 196, 225.

— — opening of flower, ii. 212.

—— scent, ii, 201.

Nicotiana rustica and N. paniculata, Koel-
reuter’s hybrids from, ii. 579,

Nicoting, i, 462.

Nidularia, coloured bracts, ii, 184,

Nigella, autogamy, ii. 354,

— movements of stamens, ii, 250.

964

Nigella, nectaries, ii. 179.
Nigella arvensis, effect of mutilation, ii.
517.
Nigella Damascena, styles, i. 645.
Nigella elata, honey-leaf, ii. 180.
Nigella sativa, honey-leaf, ii, 180.
Night-flowers, ii. 213,
Nightshade, Alpine Enchanter’s. See Circea
alpina.
— scent, ii, 202.
Nigritella, position of labellum, ii. 224.
Nigritella nigra, scent, ii. 201.
Nigritella suaveolens, hybrid, ii, 563, 586.
—— hybrid, colour of flowers, ii. 567,
Nipple-wort. See Lapsana.
Nissolia, phyllodes, i. 335.
Nitella, characteristic feature, ii. 661.
Nitella syncarpa, freezing, i. 540, 542.
Nitric acid, agent in weathering, i. 83.
—— earliest source, i. 64,
— — reduction, i. 458,
— — sources of, i. 83.
Nitrification of soil, by Bacteria, ii, 624.
Nitrogen, i, 258.
— fixation by Bacteria, ii. 624.
— in albumen, i, 457.
—non-accumulation from hydrophytes, i.
261.
— percentage in air, i. 64.
— replacing hydrogen, i. 454.
— sources of, i. 64, 457.
Nitrogenous compounds, not respired di-
rectly, i. 495.
—-— probably obtained by water-absorbing
aérial organs, i. 241.
Nitrogenous matter, effect on glands of
Drosera, i. 144.
Nodding of flowers, and protection of
pollen, ii. 119.
Nodes, of stem, i. 396, 658.
—relation of hairs to, in Stellaria media, i.
227.
Noéa spinosissima, spinosity, i. 444,
Nolanacee, ii. 771.
Nonnea, pollen-grains, ii. 99.
Non-saprophytes, on trees, i. 106.
Norway Maple. See Acer platanoides.
Nostoc and Collema, ii. 694.
— association with other plants, ii. 622,
Nostoc edule, ii. 621.
Nostocacez, as Lichen-algee, ii. 692.
— description, ii. 621.
— filaments, i. 586.
— habit, i. 589.
Nostocinez, lime incrusted, i. 260.
— loss of bulk through loss of water, i. 216,
Notochlena Marantz, rolling up of frond, i.
314.
Nottingham Catchfly. See Silene nutans.
Nucellus, of ovule, ii. 72, 81, 644.
Nucleus, of cell, and starch-formation in
Spirogyra, ii. 657.
— — central organ, i. 53.
—— composition, &e., i. 41.
— — functions, ii. 493.
— — importance of, i. 48.
— — in streaming protoplasm, i. 34.
— — structure, i. 569.
—— structure and division, i. 580, 581.
— of ovule, i. 644,
— of starch grain, i. 460.
Nullipores, fossil Floridez, ii. 614.
Nuphar, ovary, ii. 75.
— position of stomata on leaves, i. 280.
Nuphar intermedium, fertility, ii. 590.
— — mean cross, ii. 558,
Nuphar luteum and N. pumilum, hybrid,
ii, 558, 589.
Nutating tendrils, i. 696.
Nutation, of roots, i. 774.
— of twining stems, i. 683.
Nut, embryo protection, ii. 450.
— nature of, ii. 429,
“Nut-cracker” and Walnut, &c., ii. 446.
Nutmeg. See Myristica moschata.
Nutrition and gamete-formation, ii. 641.
— and sexual organs of Vaucheria, ii. 644,

INDEX.

Nutrition, mode of, best determined by
artificial cultures, i. 104.

— of plants, mutation, translocation, &c., of
substances concerned in, i. 258.

Nux-vomica, cells from seed, i. 45.

Nyctaginacez, calcium oxalate crystals, i. 570.

—- perianth, ii. 749.

— pollen-grains, ii. 97, 102.

Nyctaginez, ii. 196.

Nyctandra, dehiscence of pollen-sacs, ii. 93.

— stamen, ii. 91.

Nymphea, floating fruits, ii. 848.

— leaf and transpiration, i. 288.

— position of stomata on leaves, i. 280.

— protection of pollen, ii. 113.

Nympheza alba, ash of, i. 69.

——vcontrivance for getting rid of rain-

water, i. 288.

— — habit and habitat, ii, 511.

— — latitude and closing, ii. 218.

— — pollen-grains, ii. 99, 100.

Nymphea coerulea, scent, ii. 201.

Nymphza Devoniensis, size of flowers, ii.
185.

Nymphea gigantea, size of flowers, ii. 185.

Nymphza guianensis, epiphyllous buds, ii.
43.

Nymphea Lotus and N. dentata, hybrid and
sepals, ii. 576.

— — anthocyanin, i. 521.

Nymphea thermalis, anthocyanin, i. 521.

Nympheacee, anther, ii. 90.

0.

Oak. See Quercus.

Oak-apples, nature of, ii. 528.

Oak-galls, various, ii. 541.

Oak-leaves, galls on, ii. 552.

Oat. See Avena sativa.

Oats, pollination, ii. 142,

— starch, i. 459.

Obione halimifolia, ‘‘deaf” fruits, ii. 468,

Ochna, flower and fruit, ii. 778.

Ochrus, phyllodes, i. 335.

Ocymum and cold, i. 545.

Ocymum Basilicum, pericarp mucilage, i.
615.

Odontidium hiemale, in spring above Arzler
Alp, i 71. ~

Odontites, parasitic, i. 176.

Odontites lutea, culture experiment, i. 180.

Odontoglossum, edible fleshy growths, i. 170.

Odontoglossum Rossii, duration of flowering,
ii, 214.

Odour, and poisonous properties, i. 431.

Odours, variety in a genus, &c., ii. 487.

Cdogoniacess, ii. 650.

(Edogonium and Chytridium Olla, ii. 669.

— chlorophyll body, i. 373.

— life-history, ii. 650.

Cnanthic acid, ii. 202.

(nothera, and insect visits, ii. 223,

— downward pull of roots, i. 767.

— moths and pollen, ii. 247,

— opening of flower, ii. 212.

— stigma, ii. 283.

Cnothera biennis, autogamy, ii. 253.

— — flower, ii. 247.

— — inflorescence, ii. 282.

— — pollen-grains with viscin threads, ii.101.

Cnothera grandiflora, opening of flower, ii.

212,

Cnothera muricata, autogamy, ii, 253,

Offshoots, ciliated, ii, 802.

— dispersal by water, ii. 805.

— formation and climatic conditions, ii. 453.

— on runners, ii. 801,

— propagation by, ii. 790.

Oil, of bitter almonds, i. 462.

— of cloves, ii. 200.

— of Neroli, source, ii. 203.

— of turpentine, lavender, &c., i. 461.

Oken, nature-philosophy (1810), i. 13.

Olacacen, ii. 754.

Old Man’s Beard Lichen. See Usnea barbata.

Old World, hairiness of plants on steppes and
deserts, i. 317.

Oleaceee, ii. 771.

Oleander. See Nerium Oleander.

Olfactory organs, in man and animals, ii. 204,

Olive grove on the shores of Lake Garda, i.
275.

— oil, decomposition, i. 462.

Olive-tree, stomata, i. 280.

Ombrophytum, appearance and dimensions,
i. 196.

— Peruvian name, i. 196.

Omphalia, in salt-mine at Hallstatt, i. 101.

Omphalodes verna, flower colour and sur-
roundings, ii. 194.

Onagracer, ii. 781.

— pollen-grains, ii. 99, 102.

Oncidium, aérial roots, i. 222, 753.

— edible fleshy growths, ii. 170.

Oncidium Papilio, Pl. XIII.

— — animal mimicry, ii. 229.

Onion. See Allium.

Onobrychis, insects and keel movements, ii.

Onobrychis zquidentata, hooked fruit, ii. 873.

Onobrychis cornuta, spinosity, i. 444.

Ononis, pollen expulsion, ii. 260.

Onopordon, method of water-conduction, i. 96.

— movements of stamens, ii. 252.

— protection of pollen, ii, 126.

— spiny leaves, i. 438.

Onosma, bristles, i. 441.

Ontogeny and phyllogeny, ii. 608.

Oogonia, of Achlya lignicola, ii. 671.

Oogonium, definition, ii. 47.

— of Fucus vesiculosus, ii. 663.

Oomycetes, characteristics, ii. 668.

Oophyte, of Pteridophyta, characteristics, ii.
704.

Ooplasm, protection in Phanerogams, ii. 72.

Ooplast, of Phanerogams, ii. 81.

Oospheres, of Chlorophycez, ii. 628.

Oospore, of Chlorophycee, ii. 628.

Opegrapha lithyrga, habitat, i. 117,

Opera Girl. See Mantisia.

Operculum, of Moss capsule, ii. 702.

Ophelia, nectaries, ii. 178.

Ophiogl hb istics, ii. 709.

— two kinds of fronds, ii. 12.

Ophioglossum vulgatum, radical buds, ii. 28.

Ophrys cornuta, flower, ii. 226.

— — insect platform, ii. 227.

Opium, latex of Papaver somniferum, i. 470.

Opium Poppy. See Papaver somniferum.

Opoponax Cretica, seed-dispersal, ii. 853.

Opuntia, insect platform, ii. 229.

— irritable staminal filaments, ii. 264.

— opening of flower, ii. 212.

— protection of pollen, ii. 113.

— spines, i. 446.

— stem structure, i. 327.

Opuntia nana, recurrent opening, ii, 213.

— — stigma, ii. 279.

Opuntia Rafinesquii, barbed bristles, i. 439.

Orache. See Atriplex.

Oraches, and animals, i, 432.

— trimethylamine, i. 462.

Orange-flower scent, ii, 203.

Orange Lily. See Lilium croceum and L.
bulbiferum.

Orange-tree, odours, i. 461.

Orchid inflorescence, position of flowers to
axis, ii, 256,

Orchidacese, characteristic of flower, ii. 736.

— cleistogamy in, ii. 393.

— epiphyllous buds, ii. 43.

— hybrids among, ii. 583.

— ovary, ii. 77.

- pollination, details, ii, 253.

— subdivisions, ii, 736.

Orchids, anther, ii. 93.

— aqueous tissue, i. 328.

— chlorophyll in roots, i. 766.

— chlorophyll in seeds, &c., i. 376.

— conducting tissue for pollen-tubes, ii. 410,

— cross-fertilization, ii, 302.

— cylindrical leaves in, i, 327.

Orchids, depth of tuberous roots, i, 552.

— embryo detachment, ii. 450.

— epiphytic, i. 77.

— — protective function of water-absorbing
layers in drought, i, 223,

— — roots, clamp-cells, i. 220,

—— — double function of, i, 220.

=— ee apparatus for pollen-transfer, ii.

— flour-like coating on lip, ii. 169.

— good and bad flowering years, ii, 472.

— great variety, ii. 738.

— hybrid flower colour, ii. 567.

— labellum, ii. 253,

— leaf-bud, emergence from soil, i. C‘0.

— light seeds, ii. 851.

— mode of adhering to bark, i. 107.

— nectaries, ii. 176.’

— opening of flowers, ii, 212.

— origin of nucellus, ii. 84.

— pollen retention, ti. 283,

— pollen-sacs, ii. 90.

— roots, adventitious, i, 751,

—— aérial, i. 753.

—— origin, i. 771.

— saprophytic, on steep rocks, i. 108.

— structure of flower, ii. 253, 736.

— sugar crystals, ii. 172.

— terrestrial, downward pull of roots, i. 767.

—— roots, i. 760,

— tropical, chlorophyll in roots, i. 375.

—— epiphytic, thick cuticle, i. 309.

—— nature of scents, ii, 199,

— twisting of ovary, ii. 224.

— venation, i, 634,

— West Indian, Pl. XIII.

-- whose stomata lie in hollow tubercles, i.
300.

— withering of perianth and pollination, ii.
286.

Orchis, pollen deposition and retention, ii.
284,

— spur of labellum, ii, 255.
— variability of floral colour, ii. 569.
Orchis hircina, scent, ii. 202.
Orchis mascula, alluring spur, ii. 171.
Orchis pallens, scent, ii. 202.
Orders, of flowering plants, number, ii. 604.
Organic acids, function, i. 463.
— compounds, multiplicity of, i. 455,
—— primary, formation of, i. 455.
—— sources of, in water, i. 100.
— material, synthesis of, i. 378.
— matter, absorption of, i. 99.
—-— small amount required by most sapro-
phytes, i. 117.
— remains found in water-receptacles, i. 242.
— substances in clear springs, i. 101.
Organization, complexity, and higher de-
velopment, ii. 598.
Organs, change of function, i. 450.
— elementary early ideas of, i. 14.
— for removal of substances, i. 471.
— reduced, question of utility, i. 747.
— reproductive, protection from loss of
heat, i. 529,
—similarity of function and similarity of
structure, ii. 615,
Origanum, distribution of sexes, ii. 298,
Orlaya, peripheral flowers, ii. 186.
Oriaya grandiflora, hooked fruit, ii. 873.
— — inflorescence, ii. 184.
Ornithogalum, colour of flower, ii. 183,
— epiphyllous buds, ii. 43,
— nectaries, ii. 175.
— rolled leaves, i, 348.
— stomata, position of, i. 348,
Ornithogalum nutans, ovary and fertiliza-
tion, ii. 415.
— — staminal stipules, ii. 89.
Ornithogalum umbellatum, leaf-bud, emer-
gence from soil, i. 640.
— — protection of pollen, ii. 113.
— — protogynous, ii. 311.
Orobanchacew, ii. 771.
—embryo, &c., i. 184.
— establishment on host, i. 184.

INDEX,

Orobanchacess, features used for classifica-
tion, i. 186.

— general resemblance to Orchidew, i. 184,

— geographical distribution, &c,, i. 186.

— germination, i. 750.

— pollen-sprinkling appara'* in, ii. 271.

Orobanche, embryo, i. 596.

— former view regarding, i, 185.

Orobanche caryophyllacea, &c., scent, ii. 201.

Orobanche Epithymum, germination, i. 173.

Orobus, keel movements and pollen brush,
ii. 252.

Orobus Pannonicus, roots, i. 760.

aes venetus, floral change of colour, ii.

Orobus vernus, elevation and coloration, ii.
511.

— — seed dispersal, ii. 835.

Orpine. See Sedum Telephium.

Orthostichies, of leaves, i. 397.

— relation to divergence, i. 403.

Orthotrichum, hybrids, ii. 583.

Orthotrichum fallax, mode of adhering to
bark, i. 106.

Orthotropous ovule, i. 644.

Oryza clandestina, venation, i. 633.

Oscillaria, movement of, i. 39.

Oscillaria tenuis, verdigris-coloured films, i.

05.

Oscillarias and heat, i. 554.

Oscillatoriez, circular movements, i. 684,

Osier Willow. See Salix viminalis.

Osmia, pollen brush, ii. 168.

Osmosis, nature of, i. 59.

Osmunda regalis, frond, ii. 476.

— — sporangia, ii. 12.

Osmundacee, characteristics, ii. 709.

Ostracoda, resemblance of Utricularia
bladders to, i. 122.

Ostrya, cupule, ii. 435,

— mode of fertilization unknown, ii. 413,

— venation, i. 631.

— vernation, i. 350.

Ostrya carpinifolia, isolated colonies, i, 528.

— — wind-dispersal, ii. 848.

Ousting of plants by other plants, i. 268.

Outline of classification, ii. 617.

Ouvirandra fenestralis, Madagascar, ii. 738.

Ovaries, classification, ii. 75 et seq.

Ovaries, Phanerogamice, ii. '73.

Ovary and antholysis, ii. 79.

— discussion of structure, ii. 78 et seq.

— inferior, nature of, ii. 79.

— in Orchidacez, ii. 253.

— nature and modifications, i, 642.

— of Colocasia antiquorum, ii. 742.

Over-transpiration, prevention of in Grasses,
i. 344,

Ovule, a macrosporangium, ii. 478.

—chalazogamic fertilization in Carpinus,
ii. 412.

— homology, ii. 717.

— morphological considerations, i, 643,

— morphological value, ii. 84,

— of Gymnosperms, ii. 418,

— parts of, i. 644,

— sorts of, i. 644,

— structure, ii. 80, 416.

— transformation into tuber or bud, fi. 469,

Ovules, ii. 83.

—and nocturnal radiation, i. 529.

— arrangement on carpels, i. 644.

— attraction for pollen-tubes, ii. 414,

— of Cycads, ii. 720.

Ovuliferous scale, of Abietinex, ii. 721.

—— of Pinus sylvestris and other Conifers,

ii. 441.

— shoot of Taxus, ii. 442.

Oxalate of lime, formation, i. 458,

Oxalic acid, combination with calcium, i. 67.

— — function, i. 458, 463.

Oxalidacex, cleistogamy in, ii. 393.

Oxalis, estivation, ii. 210.

— capsule, ii. 431.

— drooping of flowers, artificially induced,
ii, 122.

— heterostylism, ii. 399.

965

Oxalis, opening of flower, ii. 212.

— protection of pollen, ii, 127.

Oxalis acetosella, leaf, diurnal positions, i.

534.

— — leaf movements, i. 339,

—— seed and embryo, ii. 422.

— — seed-dispersal, ii. 834.

— — unfolding leaves, i. 349.

Oxalis lasiandra, duration of flowering, ii.
213,

Oxalis rosea, movements of cotyledons, i.

Oxalis sensitiva, leaf, diurnal positions, i.
534.

— — movements of cotyledons, i. 532,

— — sensitiveness, i, 535 et seq.

Oxalis stricta, weather and autogamy, ii. 391.

Oxalis Valdiviana, movements of cotyledons,
i, 532,

Ox-eye Daisy. See Leucanthemum vulgare.

Oxidation, and blue rays, i. 390.

— by Bacteria, ii. 623.

Oxlip. See Prinwila elatior, ii. 404.

Oxyanthus tubiflorus, depth of flower, ii.
180,

Oxybaphus, seed, mucilage organs, i. 615.

Oxybaphus nyctagineus, pollen-grains, ii. 97.

Oxycoccacer, ii. 770.

Oxycoccus palustris, wax on leaves, i. 302.

Oxygen, and respiration, i. 293, 504.

— elimination of, i. 60.

— volume exhaled by plant, i. 455.

Oxythyrea funesta, and young capitula of
Composites, ii. 243,

Ps

Pachyma, sclerotia of Agaricinez, ii. 689.

Pachypappa vesicalig and mantle-gall on
Abele, ii. 530.

Pachypleurum, geitonogamy, ii. 324,

Pachysandra, coloured stamen-filaments, ii.
183.

— pollen and pollination, i. 645,

— scent, ii. 200.

Padina Pavonia, structure, i. 590.

Peederota, nectary, ii. 175.

— protogynous, ii. 311,

Peederota Ageria, cross-fertilization, ii. 301.

— — fertility, dependence on insects, ii. 402.

— — pull of roots, i. 768,

Peonia, anthocyanin, i, 484,

— protogynous, ii. 311,

Peonia pubens, vitality of spermatoplasm,
ii, 96.

Palzo-botany, importance of venation, i.
635.

Paleontology, bearing on evolution, ii. 610,

Palzozoic vegetable remains, ii. 611,

Palea, of Gramines, ii. 746,

Palisade-cells, i. 472.

—— movements of chlorophyll-granules, i,

381.
Palisade parenchyma, Pl. I.
— tissue, consumption of carbonic acid, i.

— — of leaves, i. 279.

— — varieties, i. 374.

Pallavicinia, vascular system, ii, 699,

Palmaces, description, ii. 740.

Palmella, Alga of Emericella, ii. 695.

Palmella cruenta, blood-red patches, i. 105.

Palmellaces, ii. 606.

Palms, climbing. See Rotang.

— fruit protection, ii. 445,

— germination, i. 604.

— leaves of, structure in relation to trans-
piration, i. 288.

— pollen-grains, ii. 99.

— temperature within spathe, i. 501.

— vitality of spermatoplasm, ii. 96. -

Palmyra Palm. See Borassus flabelliformis,

Pandanacew, ii. 745.

— weaving habit in, i. 677.

Pandanus, phyllotazis, i. 402.

— roots, i. 756.

966

Pandanus, stilt-roots, mechanical tissue, i.
761

Pandanus utilis, i. 758; ii. 745.

Pandorina, structure, ii. 632.

Pandorinee, ii. 606.

Pansy. See Viola tricolor,

Papaver, capsule, ii. 432.

— insect platform, ii, 229,

— nectarless, ii. 167.

— pollen-grains, ii. 99,

—preservation of stamens in Egyptian
graves, i, 262,

— protogyny in, ii. 310.

Papaver alpinum, protection of pollen, ii. 120.

Papaver Rheeas, effect of dry soil, ii. 500.

Papaver somniferum, abode for flies and

beetles, ii. 163.

— — floral markings, ii. 190.

—— possible cause of doubling, ii. 554.

—— size of flowers, ii. 185.

Papaveracez, epiphyllous buds, ii. 43,

— laticiferous tubes, i. 470.

Paphiopedilium (Cypripedium) caudatum,
size of flowers, ii. 185,

Papilionacez, zestivation of, ii. 210,

— and insect visits, ii. 210.

— cleistogamy in, ii. 393.

— floral structure, ii, 228,

— genera with explosive flowers, ii, 267.

— hairiness, i, 318,

— leaf-tendrils, i. 692.

—pollen expulsion by piston-apparatus, ii,
260.

— protandrous dichogamy in, ii. 311.

— storage of pollen, ii. 94.

— switch-plants in, i. 330.

— unfruitful artificial autogamy in, ii. 406.

Papille, protection of stomata from wetting
by, i, 293,

Pappus, nature and function, ii. 434,’

— of achenes, ii. 432.

— of Senecio viscosus and autogamy, ii. 364.

Papyrus, manufacture, ii. 746.

Papyrus antiquorum, Upper Nile, ii. 746.

Paracelsus, Bombastus, Swiss alchemist
(1493-1541), i. 2.

Parachutes, on seeds and fruits, ii. 855,

Parallelodromous venation, i. 634.

Parapbyses, of Ascomycetes, ii. 676.

— of Moss, ii. 15.

Parasite and host, intimacy of connection
between, in Lophophytum, i. 194.

— application of term and former views con-
cerning, i. 159.

— intimate union with host in Orobanchez,
i, 184,

Parasites, absorption of carbon-dioxide, i.
63,

— distinctive properties of, i. 161.

— non-green, nutrition, i, 466,

— on parasitic members of the same family
or genus, i. 213,

— sorts of, i. 161.

— source of carbon, i. 63.

Parasitic action, of Bacteria, i. 162.

— Bacteria, ii. 623.

— Fungi, and form alteration, ii. 518.

— Phanerogams, embryo, ii. 421.

— root, i. 752.

—thallophytes, formation of brood-bodies,
ii. 25.

INDEX.

Parmelia saxatilis, 4 Foliaceous Lichen, i.

Parnassia, nectaries, ii, 178,
Parnassia palustris, cross-fertilization, ii.
307.

— — duration of flowering, ii. 213.

— — flower, ii. 249.

—— illumination and growth, ii. 508.

—— movements of stamens, ii. 251.

— — scent during day, ii. 209.

—— structure of underground stem, i. 736.

— — venation, i. 633.

Paronychia Kapella, seed-dispersal, ii. 854.

Parsley Fern. See Allosorus crispus.

Parthenogenesis, a special case of offshoot
formation, ii. 468.

— discussion of true nature in Phanerogams,
ii, 467,

— in Mucorini, ii, 673.

— in Saprolegniacez, ii. 671.

— nature of, ii. 44,

Parthenogonidia, of Volvox, ii. 634.

Partners, of Lichen communities, i. 244.

Pasque Flower, See Pulsatilla,

Passifiora cirrhiflora, tendrils, i. 694.

Passiflora gracilis, tendril, i. 697.

Passiflora Kermesina, pollen-grain, ii. 100.

Passiflorales, ii. 785.

Path-finders, name applied to floral mark-

ings, ii, 190.

— — of flowers, ii. 232.

Paullinia, tendrils, i. 694,

Paulownia, scent, ii. 202.

Paulownia imperialis, inflorescence, i. 746.

Pavia, flowers, sexual conditions, ii. 296.

Pea. See Pisum.

Pear-trees, deciduous protective hairs, i. 354.

Peat, unfavourable for Fungi, i. 102,

Peat-moors,characteristic vegetation,ancient
and modern, ii. 612.

Pedalium murex, spinose fruit, ii. 875.

Pedate venation, i. 633.

Pediastrum, life-history, ii. 639.

Pediastrum granulatum, ii. 640.

— — thallidia, ii. 24.

Pedicularis, effect on host, &c., i. 179.

— heterogamy, ii. 377.

— hybrid flower colour, ii. 567.

— hybrids, ii. 585.

— nectary, ii. 174,

roots of parasitic species, i. 760.

Ped
Pp

is incarnata, anth min, i, 522,
— — autogamy, ii. 375.
Pedicularis recutita, anthc in, i. 522.

—— pollen-sprinkling apparatus, ii. 272.
Pedicularis rostrata, pollen-sprinkling, ii. 272.
Pelargonium, radical buds, ii. 28,

— thick cuticle of capitate cells, i. 230.
Pelargonium atrum, crepuscular perfume, ii.

—— periodio perfume, ii, 242.

—— scent, ii, 201.

Pelargonium heterogamum, leaves and rain
conduction, i. 95.

Pelargonium triste, and night visitors, ii. 197,

— — crepuscular perfume, ii. 208.

Peltaria alliacea, anthocyanin, i. 520.

Peltate leaf, venation, i. 632. "

Peltigera canina, Foliose Lichen, Pl. XV., ii.
694.

Pelvetia, ii. 664.

Parasitism, difficulty of determination, i, 243,

—of Monotropa roots, on fungal hyphe,
i, 253.

Parastichies, and torsion, i. 406.

Parenchyma, cortical, i. 469.

— spongy, functions, i. 473.

— — of leaves, i. 279.

Parietales, ii. 774.

Parietaria, cross-fertilization, ii, 306.

— distribution of sexes, ii. 298.

— ejection of pollen, ii. 137.

Parietaria officinalis, protogynous flowers, ii.
307.

Paris quadrifolia, autogamy, ii, 341,

—— stamen, ii. 87.

Parkia, pollen-chambers, ii. 90,

P higus bursarius, gallson Poplar petioles,
ii, 534.

Pemphigus cornicularius, gall on Pistachia,
ii, 534.

Pendent flowers and insect visitors, ii, 222.

Pendulous flowers and loss of heat, i, 529.

Penicillium, fermentative action, i. 508,

— spore-dispersal, ii, 812.

Penicillium glaucum, spores and heat, i. 554.

Penicillus, thallus, ii. 645,

Penium, chlorophyll bodies, cf. Pl. I., i. 373.

Pevium Brebissonii, ii. 492.

Pennywort. See Lysi hia Ni ia,

Penstemon, protandrous, ii. 311. .
Peperomia, buds on leaf-cuttings, ii. 43. F
Peperomia arifolia, situation of stomata, i.

Pepones, ii. 785.

Peppermint-tree.
ina.

Pepsin, action, i. 465.

— in Dionea digestive secretion, i. 150.

— secreted by Drosera glands, i. 144.

— solvent of legumin, i. 458.

Percussive apparatus, pollen distribution, ii.
260.

See Eucalyptus amygdal-

Perennials, foliage-stems, i. 656.

— light and growth, ii. 508.

— procumbent, i. 661.

— steppe and desert, heat resistance, i. 556.

Perfoliate, leaf, i. 595.

Perianth, as insect platform, ii. 225.

— functions, ii. 719.

Perianth-leaves, arrangement, i. 641.

Periblem, leaf origin, i. 649.

Pericarp, and dispersal, ii. 430.

— changes in ripening, i. 402.

Perichztium of Mosses, ii. 65.

Periderm, i. 469.

— buffer action, i. 474.

— characteristics, i. 719.

Peridermium pini, ii. 686.

— — nutrition of, i. 167.

Peridinez, description, ii. 625.

Peridium, of Gasteromycetes, ii. 689.

Perine, of pollen-grain, ii. 100.

Periodic movements and growth, ii. 220.

Perisperm, nature of, ii. 422.

Perisporiacez, distinctive character, ii. 676.

Peristome, of Moss capsule, ii. 702.

— of Moss sporogonium, ii. 15.

— of Splachnum, ii. 703.

Perithecia, of Claviceps, ii. 680.

— of Cordyceps, ii. 679.

— of Pyrenomycetes, ii. 678.

Per ra pari iti and C. 11

pastoris, ii. 525.

—— and Crucifersz, ii. 670.

Peronospora violacea and stamens of Knautia
arvensis, ii, 524,

Peronospora viticola, ii. 57, 670.

Peronosporew, ii. 606.

— life-history, ii. 56, 669,

— spore-formation, ii. 22.

Persian steppes, spinose shrubs, i. 435.

Persica vulgaris, cotyledons, i. 608.

Perspiring, of plants, i. 273.

Petals and autogamy, ii. 365.

— and nocturnal radiation, i: 530.

— chlorophyll in, i. 376.

— origin, ii. 86.

— withering after pollination, ii. 286.

Petasites, flowering and flowerless shoots, i.
652.

— imperfect flowers, ii. 295.

Petioles, twisting of, i. 417.

“Petites espéces”, replace one another, ii.
884,

Bursa-

Petit grain”, from Orange leaves, i. 461.

Petiveria, unequal cotyledons, i. 622.

Petroseli sativum, p, ii, 427.

Petunia, propagation of hybrids, ii. 556.

— scent, ii. 202.

Petunia violacea, nocturnal perfume, ii. 208.

Peziza, spore-dispersal, ii. 825.

Peziza eeruginosa, cause of green-rot in trees,
i, 263,

— — habitat, &c., ii, 682.

Peziza scutellata, ii, 682.

Peziza vesiculosa, ii. 19, 683.

Peziza Willkommii, effect on host, i, 168.

— — on Larix Europea, ii, 522.

Phaca, explosive flowers, ii, 267.

Phenology and climatology, i. 565.

Pr hycese, char: istics, ii, 661.

go of Thallophyta, ii. 620.

Penstemon, absorptive cells on root, i. 87.
— cross-fertilization, ii. 304.
— pollen deposition, ii. 278.

sis grandiflora, duration of flower-
ing, ii, 214.
Phalzenopsis Schilleriana, adherent roots, i.
107

Phalenopsis Schilleriana, clinging roots, i.

— — pollination, ii, 227.
Phalaris arundinacea, protection of stomata
from moisture, i, 294,
— — weather-cock leaves, i, 427.
ane shrivelling through loss of water, i.
16,

Phallus caninus, sphere-orystals, i. 457.

Phallus impudicus, ii. 691.

— — spore-dispersal, ii, 827.

Phanerogamia, absence of fossil connecting
links with lower groups, ii. 613.

— alternation of generations, ii. 478.

— analogies with Rhizocarpew and Sela-
ae in female reproductive organs,
ii, 69.

— aquatic, mode of attachment, i. 77.

— corrosive power of roots, experimental
illustration, i, 258.

—discussion of true nature of partheno-
genesis, ii, 467.

— embryo differentiation, ii. 450.

— fertilized in the air, ii, 71.

— general characters, ii. 717.

— homologies of reproductive organs, ii. 717.

— mechanical action of roots, i. 265.

— number and grouping in Genera Plant-
arum of B, and H., ii. 604.

— pollen and water, ii. 106.

— pollen-sac arrangement, ii. 89,

— saprophytic, in meadows, i. 112,

— sub-phylla, ii. 719.

Phanerogamic ovaries, ii. '77.

Phaseolus, leaf movements, i. 339.

Phaseolus vulgaris, nutation, i. 683.

Philadelphus, separation-layer, i. 361,

Phillyrea, pollination, ii. 138.

Philodendron, leaves cover air-roots, i. 225.

Philodendron bipinnatifidum stem, ii. 745.

Philodendron imbe, i. 365; ii. 744.

Philodendron Lindenii, root-hairs, i. 224.

Philodendron pertusum, i. 365; ii. '744.

— — aérial roots, i. 366.

Philosophia Botanica, of Linnzeus, definition
of varieties, ii, 514.

Phleum, pollination, ii. 142.

Phlomis, hairiness, i. 317.

Phlox, honey protection, ii. 241.

— protection of pollen from wet, ii, 111.
Phoenix dactylifera, absorbent end of coty-
ledon, i. 600.

—— germination, i. 607.
-- hanical tissue t, i. 729.
— — vitality of spermatoplasm, ii. 96.
Phosphorescence and light of Fungi, i. 503.
— of sea, caused by Dinoflagellata, ii. 625.
Phosphoric acid, ferment action, i. 465.
Phosphorus, in ash of plants, i. 66.

— necessary for nitrogen compounds, i. 67.
Phragmites communis, ash constituents, i.

t, i, 731.

1 tissue arr

— — spreading of, ii. 798.

“Phrygana”, of Theophrastus, i.e. semi-
shrubs, i. 444.

Phrygian form, produced by animals, i. 445.

Phycocyanin, pigment of Cyanophycez, ii.
621.

Phycoérythrin, i. 460,

— fluorescence, i. 379, 390.

— function, i. 390.

Phycomycetes, characters, ii. 668.

Phycophzin, pigment of Phzophycex, ii.
661.

Phygelius, protogynous, ii. 311.

Phygelius capensis, flower, ii. 181.

— — flowers and antogamy, il. 384.

Phyllanthus, phyllocladous plants, i. 334.

Phyllanthus cyclanthera, anthers, ii. 90.

Phyllanthus speciosus, i. 335.

Phyllobium dimorphum, life-history, ii. 638,

Phylloclades, in Chenopodiaces, ii. 749.

— leaf-branches, i. 333.

— of Colletia, &c., i, 334.

Phyllode, nature of, i. 335.

— of Acacia, i. 637.

INDEX.

Phyllodes, distribution of stomata on, i, 281.

Phylloglossum, general structure, ii, 715,

Phyllosiphon arisari, life-cycle; ii, 643,

Phyllostachys bambusoides, protection of
stomata from moisture, i. 294.

Phyllotaxis, and shape of leaves, i, 408,

— determination of, i. 403.

— of stamens, ii, 85,

— plan of whorled, i. 397.

— plans of spiral, i. 400.

— various series, i. 404.

Phylocladia, luminosity, i, 388.

Phylogenetic tree, ii. 620.

Phylogeny, of plants, ii. 607,

Physalis, corolla and autogamy, ii. 366,

— guides to honey, ii. 249.

— protection of pollen, ii. 118,

Physalis Alkekengi, calyx and fruit, ii. 434,

—— red pigment, i. 461.

Physcia ciliaris, apothecium, ii. 681.

Physcia parietina, Foliose Lichen, ii. 694,

Physianthus albens. See Araujia albens,

Physocytium, life-cycle, ii. 636,

Phyteuma, nectary concealment, ii. 181.

— opening of flower, ii. 211,

— storing of pollen on style, ii. 359.

Phyteuma orbiculare, autogamy, ii. 362.

— — bud-galls of Cecidomyia phyteumatis,

ii, 544,

Phyteuma spicatum, autogamy, ii. 362.

Phytolaca decandra, seed and embryo, ii.
422.

Phytophthora omnivora, on seedlings, ii.
670.

Phytoptus and fasciations in Ash, ii. 549.

—and formation of double flowers, ii. 459.

Pigment, chlorophyll-protecting, i. 392.

— of Floridew, i. 388.

Pigments, fluorescing, i. 379.

— from bacterial activity, i. 506.

— of plants, i. 460,

Pilacracez, distinctive features, ii. 687.

Pilea microphylla, ejection of pollen, ii. 137.

Pileus, of Agarics, ii. 491, 689.

— of Hymenomycetes, ii, 688.

Pilobolus cristallinus, dispersal of spores, ii.
825.

Pilostyles, distribution, i. 204,

Pilostyles Haussknechtii, mycelium-like tis-
sue in host, i. 200.

Pilularia, leaves and sporocarps, ii. 711.

Pimpernel. See Anagallis.

Pimpinella magna, anthocyanin, i, 522.

— — scent, ii, 202.

967

Pinus Cembra, dimensions, i. 722.

— — pollen-grains in snow-dust, i. 38,

—— protective resin of cones, ii. 446,

—— seed-coat, if. 439.

Pinus excelsa, cold resistance, i. 543,

Pinus Halepensis and cold, i. 543,

Pinus humilis, habit, habitat and snow, i.

548,

—— Tyrol, i. 549.

Pinus Pinea, and cold, i. 543.

— — seed-coat, ii. 439.

Pinus Pumilio, female flower, ii. 722.

—— male and female cones, ii. 144.

— — pollen-grains, ii. 98.

—— pollen storing and dispersion, ii. 145.

Pinus serotina, branch and cone, ii. 443.

Pinus Strobus and Peridermium Strobi, ii.
527.

Pinus sylvestris, age, i. 722.

— — and Coleosporium senecionis, ii. 686.

— — dimensions, i. 722.

—— ovule, structure, ii. 418.

—— ovuliferous scale, ii. 441, 721.

— — seed protection and dispersal, ii. 449.

Piper, root-forming leaves, i. 772.

— roots from leaf-cuttings, i. 88.

Piperacez, cause of white spots on leaves, i.
285.

— collective fruits in, ii. 436.

Piper Betle, collective fruit, ii. 437.

Pisonia and galls of Pemphigus cornicularius,
ii. 535.

Pisonia aculeata, sticky fruit, ii. 870.

Pistacia, pollination, ii. 138.

Pistacia Lentiscus and Witches’ Broom, ii.
527.

Pistez, characteristics, ii. 745.

Pistia, adaptation to change of habitat, i. 76.

Piston-apparatus, pollen distribution, ii. 260.

Pisum, fruit protection, ii. 446.

— keel movements and pollen brush, ii. 252.

Pitcher of Frullania, ii. 698.

Pitcher-plants, digestion of prey, i. 124.

Pitchers, i. 127.

— alluring, &c., contrivances, i. 134,

Pitfalls, advantage of, i. 158.

— structure, &., in Genlisea, i. 124.

— various shapes, i. 130.

Pith-galls, appearance, ii. 537.

Pits, bordered, of tracheides and trachee, i.

2

-— structure of, i. 45.
Pitted vessel, i. 469.
Placenta of ovary, i. 644; ii. 81.

Plagioth nekeroideum, absorption-

Pimpinella saxifraga, periodically dulous
umbels, i. 530.

Pine. See Pinus.

Pine-apple. See Ananassa sativa,

Pine-cone, phyllotaxis, i. 402.

Pinguicula, autogamy, ii. 356.

— capturing apparatus, i. 137.

— habitat, i. 140.

— nectary, ii. 178,

— number of species, &c., i. 140.

Pinguicula alpina, leaf section, i. 137.

Pinguicula vulgaris, capsule in dry and wet
weather, ii. 448.

— stamen, i. 91.

Pink. See Dianthus.

Pinus, ii. 721.

—and resistance to cold, ii. 489.

—and Witches’ Broom, ii. 527.

— branch, section, i. 22.

— cone protection, ii. 442.

— egg-cells, ii. 419.

— green cotyledons, i, 622.

— moncecious, ii. 297.

— mutilation by ruminants, ii. 515.

— mycorhiza Fungus, ii, 678.

— ovuliferous and bract scales, ii. 440.

— protection of ovules, ii. 72.

— specific value of leaf anatomy, ii. 565.

— stomata on leaves, i. 280.

— subdivision, ii. 725.

Pinus Cembra, ii. 727.

—— age, i. 722.

—— cold resistance, i. 543.

cells, i. 85,

Plains, type of community, ii. 888, 892.

Plan of whorled phyllotaxis, i. 397.

Plane-tree. See Platanus.

Plant, adaptation, i. 567.

— biennial, i. 658.

— — functions of roots, i. 751.

— — roots, i. 760.

—cycle of development and climatology, i.
564,

— division of labour, i. 367.

— fanciful comparisons of Nature-philoso-
phers, i. 12.

— moneecious, ii. 298.

— spines and prickles, i. 433.

— typical, Goethe’s, i. 12.

Plantaginacee, ii. 771.

Plantago, pollination, ii. 135.

— protection of pollen, ii. 123.

— seed-cement, i. 615.

Plantago cretica, dispersal, ii. 849.

Plantago major and animals, i. 432.

Plantago media, &c., leaves and rain conduc-

tion, i. 95.

— — spikes and radiation, i. 530.

Plantago recurvata, spikes and nocturnal
radiation, i. 530.

Plantain. See Musa paradisiaca.

Plant-body, nature of, i. 590.

— — simplest form, i. 591.

Plant communities, ii. 885.

— — types of, ii. 887.

968

Plant-formations, ii. 896.

Plant growth and crystal growth, i. 568.

Plant-lice, parthenogenesis, ii. 464.

Plant-: bers, fund tal forms, ii. 591.

Plant-migrations, nature of, ii. 904, 908.

Plants, absorption of organic matter, i. 99.

— adaptation to climatic conditions, i. 284.

— — to illumination, i. 384.

— — to life in rapidly-flowing water, ii. 502.

— — to life in very dry climate, i. 317.

— advantages of alpine habit, ii. 510.

— Alpine, absorptive cells, i. 90.

— — dwarf habit, i. 523.

—— flowering and flowerless shoots, i. 652.

—— protection of stomata by hairs, i. 292,

——with rolled leaves, reason for being
generally evergreen, i. 304.

— amphibious, characteristics, ii. 501.

— — transitional nature of, i. 75.

— anatomy of, Nehemiah Grew’s, i. 22.

— and animals as a symbiotic community, i.

254,

—and animals, difference between, i. 504,

——— no boundary-line, i. 54; ii. 620.

— and humble-bees as marauders, ii. 239.

—and injurious quantities of minerals, ii.

498.

— and selective food-absorption, ii. 497.

— anemophilous, ii. 129.

-- annual, and lack of moisture, ii. 500.

—— no scale-leaves, i. 623.

— — origin of flower-stalk, ii. 737,

— aquatic, characteristic of tissues, i. 424,

— — devoid of cuticle, i. 309.

— — nourishment of, i. 56.

—— pollen and pollination, ii. 105.

—— spiny leaves, i. 438.

— Arctic, with evergreen rolled leaves, i.
304,

—as agents in accumulation of various
mineral substances, i. 261.

— both anemo- and entomophilous, ii, 328,

— bulbous, and cold, i. 551.

— — arrangement of leaves for rain, i. 94.

— — distribution and habitats, i, 654,

—-—time of appearance in dry regions, i.

318,

— burning, i. 553,

— carnivorous in minor degree, i, 155,

—— number and classification, i. 119.

—— spinous structures in pitfalls, i. 124,

— — with adhesive apparatus, i. 153.

— classes, orders, and genera of, i. 6.

— classification, Linnean system, ii. 86.

— classified from habitat, i. 55.

— climbing, relative distribution, i. 671.

— composed of cell aggregates, division of
labour in, i. 269.

— considered from point of view of descrip-
tion and classification, i. 3.

— defenceless, protected by others, i, 451.

— distribution and heat, i. 527,

— division of labour, i. 567.

— effect of covering with earth, ii. 507,

— entomophilous, ii. 129,

— evolution, and classification, ii. 607,

— fossil, agents in preservation, ii, 612.

— freezing of, i. 539.

— glabrous in the North of Europe become
hairy in the South, i. 318.

— grouping according to substratum, ii. 496,

— heterophyllous, i. 668,

— heterostyled, ii. 302.

—influence of habitat on protection of
stomata, i. 293.

— — of mutilation, ii. 515,

— land, absorption of carbonic acid, i. 368,

—lithophytic. See Lithophytes,

— luminous, i. 502.

— main divisions, ii. 617.

—maintenance of free passage for water
vapour in, i. 290.

~— mechanical changes effected by, i. 265.

— metamorphosis of, compared to that of
insects, i, 12,

lticallular. ¢

i, 466,

ion of materials,

INDEX.

Plants, myrmecophilous, ii. 233.

— Natural History of, by Theophrastus, 300
B.C., i. 3,

— of Arctic regions, not hairy, explanation,
i, 316,

—of steppes and prairies,
covering, i. 313.

— on bark, nutrition of, i. 106.

— parasitic, no root-cap, i. 764.

— — seedlings of, i. 173.

— perennial, functions of roots, i. 781.

— phyllogeny, views concerning, ii. 607.

— poisonous, and odour, i. 431,

— preservation in snow and ice, i. 262.

— protection against animals, i. 430.

— — from freezing, i. 546,

— resistance to cold, ii. 489.

— resting condition, i. 512.

— selection of food-salts, i. 69,

— silica-loving, i. 74,

— sleep of, i. 534,

— spinose, i. 435.

— stinging, and grazing animals, i. 442.

— submerged, i. 668.

—— absence of hairs, ii. 502.

— succession and crowding-out of generation

after generation, i. 268,

——of forms in steppes, Mediterranean
district, and at Cape, with regard to
hairiness, i. 318,

—succulent, extrusion of water by leaves,

i, 271.

— — fewness of stomata, i. 280.

— — heat resistance, i. 554,

—— majority have thick cuticle, i. 309.

— — not eaten by animals, i. 432.

—-—time of appearance in dry regions, i.

318.

— summer sleep, i. 356.

— swimming, i. 669.

— symbiosis with ants, ii. 233, 243,

— synthetic activity, i. 378,

— thawing of, i, 542.

— tuberous, and cold, i. 551.

— — distribution and habitats, i. 654.

— two main subdivisions, i, 592,

— umbelliferous, water receptacles, i. 156.

— unicellular, absorption of food, i, 269,

— — transportation of materials, i. 466.

— utilitarianism, i. 421.

— utilitarian view of, i. 1,

— “viviparous”, ii: 445.

— wax on upper leaf-surfaces, i. 292,

— weapons of, i, 432.

— weaving, armature, i, 676.

— winter resting, i. 562.

— with cladodes, i. 333, 335.

— with evergreen rolled leaves, conditions of
life, i. 305,

— with explosive flowers, ii. 268,

— with rolled leaves, at Cape, localization of,
i, 306.

———-— wide distribution of, i. 303.

— with sticky foliage, ii. 236,

— with two-coloured leaves, habitats of, i. 293.

— woody, time of appearance in dry regions,
i. 318.

Plant-species, isolated colonies, i. 527.

Plant succession and substratum, ii, 498.

— world and its history, ii. 3.

Plasmodia, behaviour towards light, i. 32.

— food-absorption, i. 113.

Plasmodiophora Brassic, ii. 619.

— — galls on Brassica oleracea, ii. 522.

Plasmopora viticola. See Peronospora viti-
cola.

Plasticmaterials, solid, conduction and trans-

formation, i. 481,
— — storing of, i. 479.
—— withdrawal from leaves in autumn, i.

varnish-like

488.
Platanus, age, i. 720.
— pollen storing and dispersion, ii. 146,
— pollination, ii. 133.
— protection of pollen, ii, 117.
Platanus orientalis, dimensions, i, 722.
Plate, nuclear, i, 581.

Platycerium elniocs ii. 475.

— — epiphytic, ii. 705.

= cnle and fertile fronds, ii. 476.

Plectocomia elongata, inflorescence, i. 745.

Pleodorina, structure, ii. 633.

Pleurocarpous Moss, ii. 702.

Pleurococcacez, description, ii. 636,

— symbiosis with animal and vegetable or-
ganisms, ii. 637.

Pleurococcus vulgaris, structure, &c., ii. 636.

Pliny, Historia naturalis, ii. 1.

— plant-forms known to, ii. 600.

Pliner See, biological station, ii, 622.

Plum. See Prunus communis,

Plumbaginacee, ii. 770.

Plumbago capensis, sticky fruit, ii. 870.

Plumbago europea, flower, ii. 236.

Plusia chrysitis, victim of Araujia, ii. 260.

Plusia precationis, victim of Araujia, ii. 260.

Poa, bulbils, ii. 818.

— pollination, ii. 142.

Poa alpina, plant with bulbils, ii. 445.

Poa annua, anthocyanin in glumes, i. 522.

—— habit and elevation, ii. 512.

Poa laxa, vertical range, ii. 746,

Pocket-galls, structure, ii. 531.

Pocket-plums, cause of, ii. 524.

Pod, nature of, ii. 432.

Podophyllum, anthocyanin, i. 484,

Podophyllum peltatum, emergence of leaf

from soil, i. 639,

— — protection of pollen, ii. 127.

Podosphera, development of embryo, ii. 60.

Podostemacez, ii. 757.

—ada ion to envirc t, i, 424,

— in rushing water, i. 79.

Poison, of stinging hairs, i. 441.

Poisons, protective, i. 431.

Polar expeditions, temperature observations,
ae -

Polarization, and cell-wall, i. 568.

Polar nuclei, and endosperm formation, ii.
421.

Polemoniaces, ii. 771.

— autogamy in, ii. 384.

— dichogamy in, ii. 312.

Polemonium, nectary, ii. 175.

Pollarding, object of, ii. 37.

Pollen, abortive, ii. 403.

— amount in anemophilous plants, ii. 151.

— and guidance to honey, ii. 248.

— behaviour in cleistogamous flowers, ii. 392.

— collection by insects, ii. 133.

— contrivances for removal from anther, ii.
359,

— deposition, ii. 277, 280.

— dispersal, ii. 103.

— explosive ejection, ii. 137.

— expulsion in certain Papilionaces, ii. 260.

— foreign, possible influence in variation, ii.
593.

— insect food, ii. 167.

— mixing on stigmas, ii. 403.

~— morphological value, ii. 85.

— poverty in honey-bearing flowers, ii. 169,

— prepotency of, ii. 406,

— protection from rain and dew. ii. 107.

— protection from wet, ii. 109, 121.

— retention after deposition, ii, 282.

— storage of, ii. 94, 146, 147.

— times of discharge, ii. 142.

— transference in Asclepiadaces, ii, 257.

— — to insects, ii, 243, 247.

— transport, by egg-laying insects, ii. 157.

— — direction of, ii. 136,

Pollen-cell, division of contents in Conifers,

ii. 420.

— — effect of wetting, ii. 106,

Pollen-cells, differences in heterostyled
flowers, ii. 405.

Pollen-grain, functional adaptations, ii. 103,

— — germination in Gymnosperms, ii. 420.

— germination on foreign pistil, ii, 414,

—— =microspore, ii. 478,

Pollen-grains, ii, 98, 99.

— — dimensions, ii, 97,

— — formation, ii. 96,

Pollen-grains of Abietines, ii, 721.

—— oil on, ii. 101,

— — sculpturing, ii. 100.

— — specific differences, ii. 490.

—— viscin, ii. 101,

Pollen-masses, concealment and withdrawal,

ii, 252.

Pollen-mother-cells, ii. 96,

Pollen-sac=microsporangium, ii, 478,

Pollen-sacs, dehiscence, ii, 91.

Pollen tetrads and sticky stigmas, ii, 283,

Pollen transference, explosive apparatus, ii.
266, 267.

—— percussive apparatus, ii. 261.

—— sprinkling apparatus, ii. 271, 273, 275.

Pollen-tube, attraction by sugar-solutions, ii.
413,

—— course, ii. 408.

———in Rock-rose, ii. 411.

— — development of, ii. 106, 409.

—— nuclei and fertilization, ii, 416.

Pollination, adaptation to, i. 740 et seq.

— after results, ii, 285,

— agents in, ii. 129,

—and fertilization, interval bet

— and insects, ii. 95.

— and withering of corolla, ii. 286.

— by kangaroos, ii. 230.

— conditions of successful, ii. 405,

— of Vallisneria, ii. 132.

— relation to fertilization, ii. 401.

Pollinia, nature of, ii. 97.

— of Epipactis latifolia, ii. 255.

— of Epipogium aphyllum, ii, 226.

— of Phalzenopsis Schilleriana, ii, 227.

Polyembryony, in Angiosperms, ii. 468.

Polygala amara, stamen, ii. 87.

Polygalacex, cleistogamy in, ii. 393.

— staminal filament, ii. 88.

Polygonacez, phyllocladous species, i. 334.

— rolling of leaf, i. 348,

Polygonatum verticillatum,mechanicaltissue
arrangement, i. 730.

Polygonum amphibium, leaf-rosette, i. 412,

—— protection of stomata from moisture, i.

- 294,

n, ii, 285.

Polygonum Bistorta, effect of mutilation, ii.
517.

— — geitonogamy, ii. 327.

Polygonum bulbiferum, bulbils, ii. 454.

Polygonum Convolvulus, twining, i. 682, 685.

Polygonum Sieboldi, seed-dispersal, ii. 853.

Polygonum virginicum, seed-dispersal, ii. 841.

Polygonum viviparum, dispersal of bulbils,

ii. 454, 819.

— — ice-melting, i. 500.

—— rolling of leaf, i. 348.

Polyhedra, of Hydrodictyon, ii. 641,

Polypetale, floral characteristic, ii. 748.

— of Bentham and Hooker, ii. 604.

Polyphagus Euglenz, i. 169; ii. 668.

— — life-history, i. 170; ii. 671.

Polypodiacezs, description, ii. 706.

— sporangium, ii. 705.

Polypodium glaucophyllum, wax on fronds,
i, 292.

Polypodium serpens, sporogenous frond, ii.
11.

Polypodium vulgare, epiphytic, ii. 705.

Polyporez, hymenium, ii. 688.

— hyphe of, i. 165.

Polyporus, destructive nature, ii. 688.

— fossil remains, ii. 614.

Polyporus annosus, ii. 688.

Polyporus fomentarius, Pl. XIV. ii. 688,

Polyporus igniarius, ii. 688.

Polyporus perennis, ii. 685.

Polyporus sulfureus, behaviour of mycelium,
i. 167.

— — cause of mouldering in wood, i. 263.

Polysiphonia, luminosity, i. 388.

Polystigma rubrum, host, &c., ii. 678.

Polytrichaceze, epiphragm, ii. 703.

— teeth of peristome, ii. '703.

Polytrichum, apophysis, ii. 702,

— folding of leaf, i. 346.

— green absorptive cells, i. 85.

INDEX,

Polytrichum, mechanism for water-absorp-
tion, i, 218.

— phyllotaxis, i. 408.

— spore-dispersal, ii. 814.

Polytrichum commune, leaf, sections, i.

346.
— — sporogonium, &c., ii, 15,
Po persistent r le, ii. 435,
Pondweeds. See Potamogeton.

Pontederia crassipes, floats, i. 638, 669.
Poplar, suitability as host for Mistletoe, i.
9.

Poppy, in Egyptian tombs, i. 580.

— metamorphoses of the leaves, i. 11.

Populus, dissemination, i. 614.

— numerous hybrids, ii. 583.

— pollination, ii. 133. *

— porogamic fertilization, ii. 413,

— protection of pollen, ii. 119.

— water-absorption, direct from atmosphere,
i, 238,

Populus alba, age, i. 722.

—-— deciduous protective woolly hairs, i.

354.

— — dimensions, i. 722.
—— mycelial mantle of roots, i. 250.
— — pistillate flowers and Taphrina aurea, ii.
524,
Populus nigra, adventitious buds, i. 766.
——plants and animals which live upon,
within, or in association with, i. 256.
Populus pyramidalis, venation, i. 631.
Populus tremula and nut-galls of Saperda
populnea, ii. 543.
— — development of adventitious root-buds,
ii. 26.
— — elastic petioles, i. 428.
—— leaf, absorption-cups in surface view
and section, i. 233.
— — linear arrangement of offshoots, ii. 795.
—— normal and sucker leaves, ii. 515.
— — seed, ii. 423.
— — two kinds of leaves, i. 238.
— — variety in asexual shoots, ii. 471.
Porlieria hygrometri leaf mo
339.
Porogamic fertilization, ii. 412.
Porous cells, of Leucobryum, Sphagnum
and Lelia gracilis, i. 219.
— dehiscence of pollen-sacs, ii. 92.
—envelope of Orchid aérial roots, exfolia-
tion in soil, i. 223.
Porphyra, habit, i. 587,
Portulaca, pollen-grains, ii. 98.
— propagation of hybrids, ii. 556.
Portulaca grandiflora, &c., opening and
closing, ii. 212,
Portulaca oleracea, weather and autogamy,
ii. 391.
Posidonia, pollen and pollization, ii. 104.
Posoqueria fragrans, flower and visitors, ii.

7

i,

Potamogetacez, embryos, ii. 738.

— habit and pollination, ii. 738.

Potamogeton, adaptation to environment, i.
424.

— dichogamy, ii. 135.

— pollen dispersion, ii. 105.

— pollination, ii. 133.

Potamogeton crispus, ii. 739.

— — hibernating shoots, i. 551, 552.

—— pollination, ii, 148.

— — protogynous, ii. 311,

Potamogeton fluitans; habit and habitat, ii.

502. be

— — length, i. 388.

Potamogeton heterophyllus, &., heterophyl-
lous, i. 668. :

Potamogeton lucens, amount of lime forma-
tion, experimental determination, i. 261.

Potamogeton natans, position of stomata on
leaves, i. 280.

Potassium, in ash of plants, i. 66.

— salts of, accumulation through plants, i.
261. .

Potato, sprouting, i. 494, 562,

— starch, i, 459.

969

Potato-disease, due to Phytophthora infes-
tans, ii. 669,

“Potato-rain”, cause of, i. 651.

— — superstition concerning, ii. 810,

Potentilla, hybrids, inexhaustible, ii. 585.

— receptacles and carpels, ii. 76,

— Marsh. See Comarum palustre.

— nectary, ii. 174.

Potentilla atrosanguinea, autogamy, ii. 381.

Potentilla cinerea, hairs, i. 322.

Potentilla Clusiana, procumbent, i. 662.

Potentilla micrantha, flower, ii. 174.

— — nectary concealment, ii. 181.

Potentilla nitida, procumbent, i. 662.

Potentilla repens, autogamy, ii. 381.

Potentilla reptans, runner, i. 664.

Poterium, pollen discharge, ii. 145.

— protogynous, ii. 313.

Poterium polygamum, polygamous flower-
heads, ii. 294.

Pothoidew, climbing habit, ii. 745.

Pothos, vegetative propagation, ii. 800.

Pottia intermedia, protonema, fi. 799.

Prangos, seed protection, ii. 450.

Pressure and turgidity, i. 511.

Prickles, protective, i. 433,

— sorts of, i. 439.

Prickly Pear. See Opuntia.

Primeval forest, Ceylon, ii. 741.

— — Himalayas, ii. 743.

Primordial utricle, meaning of term, i. 25.

Primula, flowers after pollination, ii. 286.

— hcterostyly, ii. 302.

— hybrids, ii. 585.

— in cultivation, ii. 575.

— pull of roots, i. 767.

Primula Auricula and P. Carniolica, colour

of flowers and hybrid, ii. 567.

— — autogamy, ii. 396, 397.

— — dichogamous blossoming, ii. 312.

— — heterostyly and hybridization, ii. 316.

—— scent, ii. 200.

Primula Cashmiriana, protection of pollen
from wet, ii. 111.

Primula Clusiana and Uromyces Primule
integrifolia, ii, 525.

Primula denticulata, protection of pollen
from wet, ii. 111.

Primula elatior and hybridization, ii. 404.

— — effect of mutilation, ii. 517.

Primula farinosa, effect of mutilation, ii. 517.

—— wax on leaves, i. 291.

Primula glutinosa, autogamy, ii, 396.

— — hybridization, ii. 404.

—— sticky foliage, ii. 236.

Primula hirsuta, prey capturing, i. 155,

Primula japonica, antholysis, ii. 79.

— — green flower, ii. 86.

Primula longiflora, autogamy, ii. 396, 397.

Primula minima, autogamy, ii. 396.

Primula officinalis, heterostyly and differ-

ences in pollen-grains, section, ii. 405.

— — hybridization, ii. 404,

Primula sinensis, absorption of ammonia, i.
65.

Primula veris. See P. officinalis.

Primulacez, ii. 770.

—autogamy in, ii. 341.

— heterostyly in, ii. 302.

— hybrids among, ii. 585.

— pollen and probosces of insects, ii. 248.

— protection of pollen, ii. 118.

— rolling of leaf, i, 348,

— variety of venation, i. 635.

Privet. See Ligustrum vulgare.

Probosces of insects and pollen, ii. 248,

Procumbent stem, characteristics, i. 661.

Projection of seeds, range of, ii. 839.

Prolepsis, doctrine of, i. 8.

— in formation of ‘‘ Rose Willows”, ii. 546.

—in Witches’ Broom, ii. 527.

Promycelium, of Hemibasidii, ii. 675.

Pronuba yuccasella, pollination of Yucca, ii.
157, 245.

Propagation, artificial, from roots, ii. 27.

— by brood-bodies and fertilization respect-
ively, ii. 70.

970

Propagation by leaf-cuttings, ii. 41.

— by offshoots, ii. 790.

— kinds of, ii. 6.

Protandrous dichogamy, ii. 309.

— flower, ii. 307.

— plants and hybridization, ii. 317.

Proteacez, and animals, i, 432.

— Australian, summer sleep, i. 326.

— follicle, ii. 430.

— pollen-grains, ii, 99.

— position of leaf-blades in many, i. 335.

— storage of pollen, ii. 94.

— sweeping hairs, ii. 615.

Proteales, ii. 751.

— description, ii. 750.

Protea mellifera, Australia, protection of
stomata from moisture, i. 296.

— — cuticular ramparts, i. 310.

——stomata, surface view and section, i.
297.

Protection, from loss of heat, i. 528.

— of bulbs, i. 624.

— of chlorophyll, i. 391.

— of cotyledons in germination, i. 613.

— of embryo, ii. 442, 601.

— of flowers, by sticky glands, ii. 236.

—— by tufts of hair, ii, 240.

— of honey, by intra-floral hairs, ii. 239,

— — various contrivances, ii. 233.

— — various devices, ii. 241.

—of leaves, against mechanical injury, i.

428,

— of plants, against animals, i. 430.

—— by snow, i. 548.

—— by spines, &e., i. 433.

— of pollen, ii. 117.

— of pollen from wet, ii. 106, 109.

— of ripening seeds against animals, ii. 444.

— of seeds against wet, ii. 448.

— of spermatoplasm and ooplasm, ii. 72.

— of sporangia, ii. 13.

—of underground roots from vermin, &c.,
i. 762.

Protective contrivances, and distribution, i.

450.

—— and loss of heat, i. 529.

— — of developing leaves, i. 348.

— envelopes of young green leaves, i. 351.

— isolation of plants by water, ii. 233.

— poisons of plants, i. 431.

Proteid-granules, in endosperm, ii. 421.

Prothallium, female, of Hydropterides, ii.
710.

— of Equisetum, ii. 712.

— of Fern, ii. 472.

— of Lycopodium annotinum, ii. 716.

— young, arising from spore, ii. 472.

Prothallus, Fern, habit of, i. 88.

Protococcoidez, as Lichen-alge, ii. 692.

— description, ii. 628 et seq.

Protococcus atlanticus, reddening of sea, i.

Protozoa afford examples of simplest type
of reproduction, ii. 630.

— and Myxomycetes, ii. 619.

Protogynous dichogamy, ii. 309.

— flower, ii. 307.

— plants and hybridization, ii. 316.

Protomycetes, ii. 674.

Protonema, of Moss, ii. 701, 799.

— of Schistostega, Pl. I.

— — luminosity, i. 385.

Protoplasm, and freezing to death, i. 552.

— continuity, and transmission of stimuli,
i, 536,

— essential part of cell, i. 26.

— formative activity, i. 572.

— importance in assimilation, i, 456.

— in cell-wall, i. 581.

— inclosed in cells, i. 25.

— motion within cell-cavities, i. 32.

— movements and chlorophyll-granules, ii.
382.

— rate of current, i. 34,

— resisting capacity, i. 553.

—selective absorption due to specific con-
stitution, i. 73,

/

INDEX.

Protoplasm, specific constitution, ii. 487.

— structure, i, 511, 569.

— theories of origin, ii. 597.

— vehicle for oxygen, i. 495.

— vitality, i. 51.

—— and cold, i. 544.

Protoplasmic strands, conducting function,
i, 466,

Protoplast, definition of term, i. 26,

— division of labour within, i. 466.

Protoplasts, amceboid, i. 31.

— chlorophyll corpuscles in, i. 30.

— ciliated, general behaviour, i. 30.

— green, behaviour towards light, i. 30.

— mode of life, i. 27.

— mutual and external relations, i. 47.

— power of renovation, ii. 45.

— problem of mutual intelligence between,
i, 49.

— sorts of, i. 28.

Prunella, distribution of sexes, ii. 298.

— honey protection, ii. 241.

— hybrids, ii. 585.

Pruning, object of, ii. 37.

Prunus, host of Polystigma rubrum, ii. 678.

Prunus armeniaca, section, i. 22.

Prunus avium, dates of flowering, i. 519.

— — drupe, ii. 428.

Prunus cerasus, cotyledons, i. 608.

Prunus communis, nectary, ii. 174.

Prunusinsititia, &c., galls of Exoascus Pruni,
ii. 524, :

Prunus Mahaleb, reserve-buds, ii. 33.

Prunus Padus, ii. 524,

Prunus spinosa, drupe, ii. 428.

—— spines, i. 443

Prussic acid, i. 462.

Pseudo-hermaphrodite flowers and dichog-
amy, ii. 312.

Pseudomorphs, Orobanche formerly con-
sidered, i. 185.

Psilotacez, description, ii. 715.

— homosporous, ii. 713.

Ptarmigans, in Alps, i. 489.

Ptelea trifoliata, flowers, sexual conditions,

ii, 296.

— — seed-dispersal, ii. 853.

Pteranthus echinatus, hooked fruit, ii. 873.

Pteridex, tribe of Polypodiacez, ii. 706.

Pteridophyta compared to Bryophyta, ii. 704.

— general\description, ii. 704.

Pterocarya, mode of fertilization unknown,
ii, 413,

Pterocarya Caucasica, cotyledons, i. 621.

Pterogonium gracile, parthenogenesis, ii.
464.

Puccinia graminis, effect on Wheat crops, ii.

687.

— — life-history, ii. 686.

Puff-balls. See Lycoperdon.

Pulmonaria, autogamy, ii. 396.

— heterostyly, ii. 302.

— protection of pollen, ii, 118,

— venation, i. 630.

Pulmonaria hybrida, characteristic hairs, ii.

Pulmovaria Lithospermum, flower colour
and surroundings, ii. 194.

Pulmonaria officinalis, winter protection, i.
550.

Pulque, i. 507.

— fermented juice of Agave Americana, i.
272.

Pulsatilla, hybrids, ii. 584.

Pulsatilla patens, protogyny and hybridiza-
tion, ii. 316,

Pulsatilla pratensis, colour of sepals, ii. 183.

Pulsatilla vernalis, distribution of sexes, ii.
298.

— nectaries, ii. 179.

Pulvinus, of leaf, function, i. 532,

Purification, due to Bacteria, i. 264.

Purple Loosestrife. See Lythrum Salicaria.

Putrefaction, and Moulds, i. 507.

— by Bacteria, ii. 623.

— nature and causes of, substances gener-
ated during, i. 263.

Putrefaction, nature of, i. 506.

Pycnidia, of Lichens, ii, 693.

— of Pyrenomycetes, ii. 678.

Pyrenoid, function, ji, 629.

— of Chlamydomonas, ii. 629.

Pyrenoids, in Spirogyra, ii. 656.

— of Hydrodictyon, ii. 640.

Pyrenolichenes, characters, ii, 694.

Pyrenomycetes, as Lichen-fungi, ii. 693.

— distinctive characters, ii. 676.

Pyrola, dehiscence of pollen-sacs, ii, 92.

Pyrola chlorantha, capsules in dry and wet
weather, ii. 448.

Pyrola media, autogamy, ii. 364.

Pyrola secunda, pollen - sprinkling, ii. 273,
274,

Pyrola uniflora, flower and autogamy, ii.

383.

—— scent, ii. 202.

—— stamen, ii. 91.

— — water-receptacles, i. 239.

Pyrolacee, ii. 768,

Pyrus, carpels, ii. 76.

— hybridization in, ii. 570.

— scent, ii. 200.

Pyrus aucuparia, and Gymnosporangium
juniperinum, ii. 686.

Pyrus communis, dates of flowering, i. 519.

—— grafting on Crateegus Oxyacantha, &c.,

ii, 571.

— — Gymnosporangium gall, ii. 520.

—— persistent receptacle, ii. 435.

Pyrus cydonia, mucilaginous seed-coat, i. 458.

Pyrus malus, carpels, ii. 76.

— — host of Mistletoe, i. 205.

—— ovary, sections, ii. 74.

Pyrus salicifolia, erroneous assertions about
origin, i, 215.

Pythium, germination, ii. 669.

Pythium de Baryanum, on seedlings, ii. 670.

Q.

Quamoclit coccinea, cotyledons, i. 621.
Quartz attacked by Lichens, i. 257.
— difficult to decompose, i. 83, 266.
Quassia amara, flowering branch, ii. 778.
Queen of the Night. See Cereus nycticalus.
Quercus, i. 716; ii. 760.
—and bud-galls of Andricus inflator, ii. 543.
——— of Aphilothrix gemme, ii. 541.
— —— of Aphilothrix Sieboldi, ii. 537, 541.
——— of Cynips Hartigii, ii. 541.
—— — of Cynips lucida, ii. 541.
— — — of Cynips polycera, ii. 541.
— —— of Dryoterus terminalis, ii. 543.
——— of Neuroterus fumipennis, ii. 537.
— —— of Neuroterus numismatus, ii. 537.
— —— of Spathegaster baccarum, ii. 526,
— and grazing animals, i, 445.
— and Peziza eruginosa, ii. 682.
—and solid gall of Cynips Kollari, ii. 541.
— bark, i. 720.
— cotyledons, i. 608; ii. 421.
— curvature of branches, i. 416.
— defoliation slow, i. 361.
— fertilization porogamic, ii. 413.
— fossil, i. 636.
— from chalk, ii. 613.
— galls on roots, ii. 541.
— germination, i. 609,
hanical tissue arra
— moneecious, ii. 297.
— numerous hybrids, ii, 583.
— nut-gall of Cynips calicis, ii, 543.
— phyllotaxis, i, 399.
— pollen-grains, ii. 99, 102.
— pollination, ii. 133, 135.
— protogynous, ii. 313.
— scale-leaves of first bud, i, 624.
— stomata, i. 280.
_ bars of wood and nutrition of Mildew,
i. 166.
— variety in foliage, ii. 471,
— vernation, i. 350.
Quercus Austriaca, seedlings, i. 607.

t, i, 729,

Quercus Cerris and Erineum quercinum, ii.
529,

— — and gall of Cecidomyia cerris, ii, 534,538,

—— and spangle-galls of Neuroterus, ii, 541,

—— staminal galls, ii. 540.

Quercus pedunculata, age, i. 720,

— — dimensions, i, 722,

— — fruiting branch, ii, 435.

— — inflorescences and flowers, ii. 298.

— — normal and sucker leaves, ii, 515.

— — numerous galls on, ii. 552.

Quercus pendulina, bud-gallsof Cynips lucida,
ii, 542.

Quercus pubescens, and gall of Cynips caput-

meduse, ii, 541.

—— influence of Cynips polycera, ii. 550.

Quercus sessiliflora, dimensions, i, 722.

— — fruiting branch, ii, 435.

— — galls on bract-scales, ii. 540,

Quickset hedge, nature of, i. 673,

Quince, See Pyrus cydonia.

Quinine, i. 462.

R.

“Race”, meaning of, ii. 581.

Raceme, i, 738.

Rachis, application of term, i. 737.

— developed into spine, i. 447.

Radiation and leaf-movements, i. 532.

Radicle, behaviour in Mistletoe, i. 206.

Radiolaria and Chlorella, symbiotic, ii. 637.

Radiolariz, symbiosis with plants, i. 254.

Radix palaris, i. 760.

Raffia Ruffii, inflorescence, i. 745.

Rafflesia, colour and odour, ii. 197.

— mycelium-like tissue in host, i. 200.

Rafflesia Arnoldii, flower, description of, &c.,
i. 203.

Rafflesia Padma, Java, size and description
of flowers, i. 203.

Rafflesia Schadenbergiana, size of flowers,
ii, 185.

Rafiflesiaceze, ii. 755.

— anthocyanin, i. 483.

— flower-stalk origin, i. 736.

— nature of scents, ii, 199.

— only European representative, i. 204.

— parasitic on trunks and branches, i. 201.

Rafflesiz, disagreeable odour, i. 199.

— geographical distribution, mc Je of growth,
size of flowers, &c., i. 203.

Ragwort. See Senecio.

Rain, agent in dispersal of offshoots, ii. 809.

— and sensitive plants, i. 536.

— carbon dioxide, sulphuric acid, and am-
monia in, i. 79.

— carbonic and nitric acid in, i. 370.

— dust collector, i. 80.

Rain-water, contrivances for retention of, i.

— — irrigation of, i. 97.

—— various modifications of cauline leaves
for conduction, i. 95.

Ramalina reticulata, Fruticose Lichen, ii.694.

Ramondia, dehiscence of pollen-sacs, ii. 92.

— pollen sprinkling, ii. 274.

Ramondia pyrenaica, stamen, ii. 91.

Rampion. See Phyteuma.

Ranales, ii. 774.

Ranunculacex, autogamy in, ii. 345, 381.

— dichogamy in, ii. 311.

— distribution of sexes, ii. 298.

— hybrids among, ii. 584.

— movements of stamens, ii. 250.

— pollen-grains, ii. 99.

— protection of pollen, ii, 118.

— protogyny in, ii. 310.

— venation, i. 633.

— Water, leaf-rosettes, i. 412.

Ranunculus, aquatic, aérial and submerged
leaves, ii. 505.

—— pollen dispersion, ii. 105.

—carpellary insect platform, ii. 229.

— storage of pollen, ii. 94.

Ranunculus acris, protection of pollen, ii, 120,

INDEX,

Ranunculus alpestris, distribution of Sexes,
ii, 298.

— — nectaries, ii, 178,

Ranunculus aquatilis, heterophyllous, i. 668.

— — lime-incrusting, i. 260.

aay baldensis, distribution of sexes,
ii, 298.

Ranunculus Baudotii, heterophyllous, i. 668.

Ranunculus bulbosus, downward pull of
roots, i, 767.

aaa a Ficaria, bud-like offshoots, ii.

— — colour of flowers, ii, 183,
—— plant and tuber-like offshoots, ii. 460.
— — tubers, i. 651.
— — tubers dispersed by floods, ii. 810,
Ranunculus fiuitans, length, i. 388.
Ranunculus glacialis, distribution of sexes,
ii, 298,
— — flower, ii. 174.
— — nectaries, ii. 178.
—— nectary concealment, ii. 181.
Ranunculus hololeucus, heterophyllous, i. 668.
Ranunculus Neapolitanus, roots, i. 760.
Ranunculus pedatus, Pl. VI.
Raphanus, pollen-grain, ii. 100.
Raphanus sativus, cotyledons, i. 621.
Raphe, of ovule, ii. 81.
Raphia tedigera, Brazil, size of leaves, i. 287.
Raphides, i. 457.
Raphidophora decursiva, ii. 743.
— — climbing habit, ii. 745.
Rariorum Plantarum Historia, by Clusius,
ii. 601. -
Raspberry. See Rubus Ideus,
Ravenala, sheltering of pollen, ii. 108.
Ravenala Madagascariensis, ii. 735.
Rays, medullary, i. 468.
Rays of spectrum, absorption, transforma-
tion, i. 379.
Reaumuria, salt on leaves and stem, i. 236.
Recapitulation-theory, ii. 608,
Receptacle, floral, i. 746.
— honey secretion, i. 747.
— in fruit-formation, ii. 435.
— persistent, ii. 434.
Red Currant. See Ribes rubrum.
Red-rot, i. 264.
Red Sea, reddened by Trichodesmiun, i, 389.
Red Sea-weeds. See Floridee.
Red Snow, ii. 627.
Red-wood. See Sequoia sempervirens,
Reed. See Phragmites communis,
Reed-like Grasses, wax on leaves, i. 292.
Reed-mace. See Z'ypha latifolia.
Reeds, contrivances for irrigation, i. 99.
— type of community, ii. 888, 893.
Rehmannia, pollen deposition, ii. 280.
Reindeer-moss. See Cladonia rangiferina.
Rejuvenescence, of plants, i. 584,
Renovation without fertilization, ii. 45.
Replun, of siliqua, ii. 432.
Reproduction, kinds of, ii. 6.
— of Chara fragilis, ii. 660.
— very simple type in Chlamydomonas, ii.
0.

Reproductive organs, homologies in Phanero-
gams and Vascular Cryptogams, ii. 478.

— — protection from loss of heat, i. 529,

Reseda, ovary, ii. '73.

Reseda odorata, artificial tree production, ii.
453.

— — scent, ii. 200, 209.

Resedacez, ovary open, ii. 775.

Reserve-buds, characteristics, ii. 34.

— — distribution, ii. 31.

Reserve materials, i. 459.

— — and enzymes, i. 464.

Reserve-tissue, food-stores, i. 598.

— — of seeds, i. 599; ii. 422.

Reservoirs, water, in leaves, i. 156.

Residual substances in autumn leaves, i. 485.

Resilient fruit-stalks and dispersal, ii. 840.

Resin and preservation of fossil plants, ii.

— and protection of fruits, ii. 446.
Respiration and germination, i. 494.

971

Respiration, chemistry of, i. 497.

— heat development, i. 497.

— in absence of oxygen, i. 504.

— in dormant organs, i. 494.

— in Mushrooms, i. 498.

— measure of energy, i. 494.

— modus operandi, i. 495.

— of plants, impelling force, i. 492.

Respiratory cavity of stoma, i. 280.

— heat and germination of seeds, i. 560.

Retama, explosive flowers, ii. 267.

— protection of stomata from moisture, i.
298.

— protective coat of wax, i. 292.

Retention of deposited pollen, ii. 279.

Rettenstein, slate mountains and character-
istic vegetation, ii. 495.

Revolver-flowered Gentians, ii. 387.

Revolver-flowers, ii. 249.

Rhacomitrie, special absorptive cells of, i.
218.

Rhamnus, drupe, ii. 428.

— hybrids in, ii, 584.

— phyllotaxis, i, 399.

Rhamuus cathartica, distribution of sexes, ii.

299,

—— pollen-grains, ii. 97.

—— scroll-galls of Trioza Rhamni, if. 531.

Rhamnus hybrida, behaviour of foliage, ii.
574,

Rhamnus pumila, lattice-forming stem, i.

Rhamuus saxatilis, distribution of sexes, ii.

— — spines, i. 443,
Rhamnus tinctoria, distribution of sexes, ii.
299.

Rhamunus Wulfenii, venation, i. 630.

Rheum, i. 94.

— and Field-mice, i. 763.

— anthocyanin, i. 484,

— geitonogamy, ii. 328.

— scale-leaves and earthing up, i. 625.

Rhinanthacee, geitonogamy, ii. 331.

— hybrids among, ii. 585,

— many parasitic, i. 176.

— nectaries, ii. 174,

— pollination, ii. 129.

— relationships to Lathreea, i. 181.

— uniformity of venation, i. 635,

Rhinanthus, nectary, ii. 174.

— pollen sprinkling, ii. 272.

— protection of pollen from wet, ii. 110.

— venation, i. 631.

Rhinanthus angustifolius, flower, ii. 273.

— — pollen-sprinkling apparatus, ii. 273.

Rhipidopteris, distribution of sporangia, ii.
706.

Rhipidopteris peltata, Mexico, two kinds of
fronds, ii. 12.

Rhipsalis, on trees, i. 106.

Rhizidiomyces, life-cycle, ii. 671.

Rhizobium, fixation of free nitrogen, ii. 624.

Rhizobotrya alpina, autogamy, ii. 335.

Rhizocarps, description, ii. 709.

Rhizoids, absorption-cells of Mosses, &c., i.
86.

— mechanical changes due to, i. 265.

—of Grimmia apocarpa, disintegrating
power, i. 258,

— of Mosses, water absorbents, i. 219.

Rhizoma, application of term, i. 624.

Rhizome, nature of, i. 652.

Rhizomes, dimensions of, ii. 797.

Rhizomorphs, of Agaricus melleus, ii. 689

Rhizophora, columnar roots, i. 759.

— compared to viviparous animal, ii. 450.

— elevation by roots, i. 771.

— germination, &c., i, 602.

— habitat, i, 602.

— no root-cap in marsh-inhabiting, i. 164.

— roots, i. 756.

Rhizophora conjugata, embryogeny, &c., i.

602.

—— flower, fruit, seed and germination, i.

-- stilt-roots, structure, i. 761,

972

Rhizophora Mangle, branch with flowers
and fruit, ii. 451,
Rhizophore, of Selaginella, ii. 715.
Rhizophoree, polleu-chambers, ii. 90.
Rhizopoda, prey of Utricularia montana, i.
123.
Rhizopus nigricans, spores and heat, i. 554.
Rhizotomoi, ancient Grecian guild of herbal-
ists, i. 2,
Rhodiola rosea, distribution of sexes, ii. 299.
Rhodites eglanteriz, pea-like gall, ii, 552.
Rhodites Rose, and Bedeguars, ii. 552,
—— gall on Rose-leaf, ii. 533.
Rhodites spinosissima, gall, ii, 552.
Rhododendron, and animals, i. 432.
— pollen tetrads, ii. 97.
— protection of pollen, ii. 118,
— sticky stigmas, ii. 282.
Rhododendron Chamecistus, cross-fertiliza-
tion, i. 301.
— — insects and pollen, ii. 245.
-— — protogynous, ii. 311.
— — viscin of pollen-grains, ii. 101.
Rhododendron ferrugineum and R. hirsu-
tum, hybrid of, ii. 564.
—— doubling of flower through Gall-gnat,
ii, 549,
— — galls of Exobasidium, ii. 520.
—— honey protection, ii, 239.
— — influence of gall-mites, ii. 550.
— —nectaries, ii. 177.
—— scroll-gall, ii. 530.
Rhododendron hirsutum, and snow, i. 550.
—— and summer cold, i. 545.
— — galls of Exobasidium, ii. 520,
—— honey protection, ii. 239,
—— leaf, under side and section, i. 232.
— — nectaries, ii, 177.
— — pollen-tetrads with viscin threads, ii.101.
—— protandrous, ii. 311,
— — scroll-gall, ii. 530.
— — weather and self- and cross-pollination,
ii, 391,
Rhododendron intermedium, autogamy, ii.
589,
Rhododendron Lapponicum, cold resistance,
i, 543,
Rhododendron Ponticum, and cold, i. 543,
Rhododendrons, Alpine, Pl. X.
— — sheltered pollen, ii. 107,
Rhodophycewx, ii. 606, 620.
Rhodoracez, ii. 768.
Rhodotypus, reserve-buds, ii. 33.
Rhopalocnemis phalloides, geographical dis-
tribution, i, 193.
—— Java, i. 191.
Rhubarb. See Rheum.
Rhus Cotinus, anthocyanin in buds, i. 484,
—— distribution of sexes, ii. 297.
— — hairy flower-stalks, ii, 858,
Rhus semialata, Aphis galls, ii. 535,
Rhus Toxicodendron. Pl. V. i. 488,
Rhus Typhinum, Pl. V. i. 488,
Rhynchosia phaseoloides, stems, i. 475, 477.
Ribbon-growths, plant community, ii, 888,
893.
Ribbon-like stems of Liane, i. 475.
Ribes alpinum, distribution of sexes, ii, 299,
— — pocket-galls on, ii. 532,
Ribes aureum, scent, ii. 201.
Ribes Grossularia, flower, ii. 236.
Ribes rubrum, flower, ii. 173.
Ricciacew, description, ii. 697.
Rice, starch, i. 459.
Richardia, moncecious, ii. 297.
Richardia eethiopica, coloured bract, ii, 184.
Richmond, Virginia, U.S.A., Diatom de-
posit, ii. 627.
Ricinus, cotyledons in germination, i. 610,
—- protection of pollen, ii. 124,
— protogynous, ii, 313.
— seed, section, i. 599.
— staminal filament, ii, 88,
— venation, i. 632.
Riciuus communis, crystalloids, i, 457.
—— distribution of sexes, ii. 300.
—— pistillate flower, moncecia, ii. 293.

INDEX.

Ricinus communis, seed and embryo, ii. 425.

— — seed-dispersal, ii. 835.

— — spiral vessels and bundle-sheath, i. 471.

— — stamen, ii. 87.

— — staminate flower, moncecia, ii. 293.

— — stem, i. 656,

Riella helicophylla, ii, 611.

Ring, annual, i. 719.

Ringed bark, i. 720.

Ringed tendrils, i, 694.

Ringing, effect of, i. 480.

— experiment, and ascent of sap, i. 276,

“Ripened” wood, i. 552,

Rivers, self-purification, i. 265.

Rivina, pollen-grains, ii. 99.

Rivularia, ii, 622.

Robinia Pseudacacia, flowering and foliage,

i, 562.

— — leaf, diurnal positions, i. 534.

— — reserve-buds, ii, 31.

—— scent, ii. 200.

—— spines, i. 449.

Rochea, functions of hairs, i. 325.

— water-storing epidermis, i. 329,

Rochea falcata, epiphyllous buds, ii. 40.

—— flinty armour, i. 323.

Rochelia persica, hooked fruit, ii. 873.

Rock, substitute for tree-trunks, i. 108.

Rocks, decomposition-of constituents, i. 83,

— smooth steep, habitat for various micro-
scopic plants and Lichens, i. 117.

Reemeria, autogamy, ii. 341.

— stigma, ii. 279.

Reemeria violacea, opening and closing, ii. 212.

Rolling fruits, ii, 849.

Root, chief distinctive feature, i. 767.

— elevating power, i. 770.

— formation due to external stimulus, i. 771.

— hydrotropism, i. 775.

— movements, i. 772, 776.

— of Ferns, apical-cell, i, 579.

— origin, i. 766.

— protection from mice and insect-larva, i.
762

— shortening and downward pull, i. 770.

— sorts of, i. 750 et seq.

— supporting, i. 754,

Root-absorption, effect of cold on, i. 356.

Root-buds, i. 766.

Root-cap, absence in certain plants, i. 764.

— — formation, i. 579.

— — function and structure, i. 763.

Root-climbers and prostrate stems, i. 708.

Root-cortex, functions, i. 762.

Root-hairs, i. 87.

— — fungal hyph as a substitute for, i. 249.

— — length, i. 86.

— — of aérial roots of Tree-ferns, i. 224.

— — on what development depends, i. 89.

—— position and renewal, i. 90.

— — retention of earth particles, i. 87.

— — thickness of inner coat, i, 88.

Root-pressure, and transpiration, i, 281, 366,

— — elevation and extrusion of sap through,
i. 271,

—-— force of, experimental determination,
i, 272.

—-— in Aroid roots, i. 366.

— — limitation of, i. 273.

Root-shortening, disperses bulbs, ii. 831.

Root-stock. See Rhizome.

Root-stocks, resting of desert perennials,i.556.

Root-system of Mistletoe, shape, i. 209.

Root-tendrils, nature, i. 694.

Roots, acid juice of, corrosive power, i, 258,

— aérial, of Aroids, i, 366.

— — of Orchid, i. 221.

—— — — adhering to bark, i. 107.

— and oxygen, i, 493,

— aquatic, structure and function, i, 763.

— artificial propagation from, ii. 27,

— behaviour in Arctic regions, i. 774.

— chlorophyll in, i. 376, 766.

— climbing, characteristics, i, 701,

— dead, source of carbonic and nitric acids,

i. 266.
— forms of, i. 749 et seq.

Roots, functions and differentiation, i. 761,

— mechanical force, i. 515.

— of Ficus, i. 755.

— — form living bridges, ii. 758, 760.

— of Lathreea, i. 182.

— of Pedicularis, behaviour, i. 180.

— of Phanerogams, mechanical changes due
to, i. 265,

— poisonous secretions, i. 763.

— positive geotropism of, i. 88.

— primary, origin, i. 771.

— shape, determining factors, i. 757.

— stilt-like, of Mangroves, i. 759.

— strap-shaped, i. 107.

Roridula, i. 148.

Roridula dentata, carnivorous in minor de-
gree, i, 156.

Roridula muscipula, source of name, ii. 235.

Roripa, hybridization, ii. 584.

Roripa amphibia, aérial and submerged

leaves, ii. 505.

—— and R. sylvestris, hybrid of, ii. 586.

Roripa palustris, epiphyllous buds, ii, 43,

Rosa, aggregate fruit, ii. 436.

— and ancient crossing, ii. 555.

— and galls of Rhodites Rose, ii. 537.

— carpellary insect platform, ii. 229.

— double hybrids, ii. 576.

— effect of grafting, ii. 571..

— hips, protection against rodents, ii. 444.

— indumenta of hybrids, ii. 564,

— innumerable hybrids, ii. 585.

— leaf with various galls, ii. 533.

— opening of flower, ii. 211, 212.

— phyllotaxis, i. 400.

— pollen-grains, ii. 99.

— prickles, i. 433, 676.

— protection of pollen, ii. 113.

— radical shoots, ii. 27.

— seed dispersal by birds, ii, 444,

— specific scents, ii. 566.

— storage of pollen, ii. 94,

— vernation, i. 350.

— weaving stem, i. 672.

Rosa alpina, scent, ii. 204.

Rosa arvensis, duration of flowering, ii. 213.

—— scent, ii. 204,

Rosa Banksiz, myrmecophilous, ii. 233.

Rosa canina and galls of Rhodites Rose, ii,

553.

— — cotyledons, i. 621.

—— scent, ii. 204.

Rosa centifolia, scent, ii, 204.

Rosa cinnamomea, scent, ii. 204.

Rosa Gallica, scent, ii. 204.

Rosa pimpinellifolia, scent, ii. 204.

Rosa rubrifolia, ii. 553.

Rosa Schottiana, receptacle and carpels,ii.74.

Rosa Thea, scent, ii. 204.

Rosacez, ii. 779.

— autogamy in, ii. 390.

— dehiscence of pollen-sacs, ii. 92.

— distribution of sexes, ii. 298.

— geitonogamy in, ii. 325.

— Phrygian, i. 444.

— protogyny in, ii. 310.

Rose-chafers, sheltering in flowers, ii. 163.

Rose of Jericho. SeeAnastatica hierochuntica.

Rose-root. See Rhodiola rosea.

Rose-trees, wiuter treatment, i. 550,

‘Rose Willows”, nature of, ii. 546.

Roses, breeding of, ii. 555.

— double, pollination of, ii. 403.

— number, ii, 555.

— transition from stamens to petals, ii, 86.

Rosettes, of leaves, i. 410.

Ross, Captain John, observes Red-snow iu
Arctic America, i. 38.

Rostellum, of Epipogium aphyllum, ii. 226.

— of Orchids, ii, 253. .

Rotang, barbs, i. 677.

— climbing habit, i, 362.

— mechanical tissue, i. 732,

— shoot apices, i. 676.

Rotangs, in Java, i. 675.

— length, i. 676,

Rotifer, in Frullania pitcher, ii. 698.

Rotifer, resistance to cold, i. 542.

— symbiosis with Liverworts, i. 225.

Rotting, and Fungi, i. 508.

Rousseau, lectures on botany, i. 6.

Royal Fern. See Osmunda regatlis.

Rubia, stipules, i. 637.

Rubiacew, ii. 763.

Rubus, indumenta of hybrids, ii. 564.

— innumerable hybrids, ii. 585.

— many formns of, ii, 900.

— nectary, ii, 174.

— prickles, i. 676.

— weaving-stem, i. 672.

Rubus bifrons, rooting branches, i. 769.

Rubus Chameemorus, water-receptacles, i.
239.

Rubus fruticosus, protective function of air-
containing hairs, i, 314.

Rubus Ideeus, aggregate fruit, ii. 436.

—— autogamy, ii. 390.

— — flower, ii. 78.

—— phyllotaxis, i. 400.

— — radical shoots, ii. 27.

—— recurrent opening, ii. 213.

— — two-coloured leaves and habitat, i. 293.

Rubus squarrosus, branches, i. 677.

Rudbeckia fulgens, colour-contrast in capitu-
lun, ii. 191.

Rumex, anthocyanin, i. 484.

— dichogamy, ii. 135,

— geitonogamy, ii. 328.

— venation, i. 630.

Rumex Acetosella, radical buds, ii. 28.

Rumex alpinus, distribution of sexes, ii, 298.

—— imperfect flower, ii. 295.

—— pollen dispersion, ii. 143.

—— protogyny, ii. 312.

Rumex nemorosus and R. obtusifolius, dicho-

gamy and hybridization, ii. 315.

—— distribution of sexes, ii. 298.

—— imperfect flowers, ii. 295.

Rumex nepalensis, hooked fruit, ii. 873.

Rumex Patientia, probable hybrid, ii. 592.

Rumex scutatus, antholysis, ii. 83.

—— pollen dispersion, ii. 143.

Rumex tuberosus, roots, i. 760.

Runner, adventitious roots, i. 751,

— dimensions of, ii. 797.

— nature of, i. 663.

— production of offshoots by, ii. 802.

Ruppia, root origin, i. 766.

Ruscus, buds on cladodes, ii. 37.

Ruscus aculeatus, cladodes, i. 332.

— — shoot, i. 333.

—— spinosity, i. 434. .

Ruscus Hypoglossum, cladodes, i. 333.

Rushes, in Alps, anthocyanin, i. 522.

Russelia, scarlet flowers, ii. 196,

Russia, Southern, lowlands of, hairiness of
plants, i, 318.

Russula, laticiferous, i. 491; ii. 689.

Rust. See Uredinee.

Rust-fungus, teleutospores, ii. 24,

Ruta, capsule, ii. 431.

— cross-fertilization, ii. 306.

— pollen-grain, ii. 100.

Ruta graveolens, flower, ii. 306.

—— scent, ii, 202.

— — seed and embryo, ii. 422.

Rutacez, honey protection in, ii. 241.

— of steppes, waxy bloom of leaves, i, 312.

8.

Saas-Fée, and Uromyces Pisi, ii. 525,

Saccharomyces, development and ferment
action, i. 506,

Saccharomyces cerevisia, ii. 681.

— — life-cycle, ii. 683.

Saccharomyces ellipsoideus,
activity, ii. 684.

Saccharnm officinarum, mechanical tissue
arrangement, i; 731.

Sachs’s table of Thallophyte classification,
ii, 606.

Sagina Linnei, nectaries, ii. 176,

fermentative

INDEX,

Sagina saxatilis, autogamy, ii. 338, 339.

Sagittaria, moncecious, ii, 297.

— protective isolation by water, ii, 234,

Sagittaria sagittifolia, leaf and habitat, ii. 502.

Sainfoin. See Onobrychis,

Salicineze, porogamic fertilization, ii. 413,

Saliva, action on granulose and cellulose, i.
460.

Salix, and galls of Nematus gallarum, ii. 537.

— colour of anthers, ii. 183,

—dates of flowering of hybrids and their
parents, ii, 574,

— deciduous bud-scales, i. 626,

— galls, ii, 531, 533, 546, 552.

—habitat in relation to water-collecting
habit, i. 240.

— hybrids, ii. 583.

— insect pollination, ii. 583.

— hani 1 tissue arraa

— phyllotaxis, i, 399,

— pollarding, ii. 37.

— pollen-graing, ii. 99,

— porogamic fertilization, ii. 413,

— protogyny, ii. 313.

— roots, i, 752.

— ternary hybrids, ii. 560.

— water-pore of nectary, ii. 172,

Salix alba, and bud-galls produced by mites,
ii. 547,

Salix amygdalina, 8S. purpurea, S. pruinosa,
protective layer of wax on leaves, i. 291.

Salix aurita, normal and sucker leaves, ii, 516.

Salix caprea, foliaceous ovule, ii. 83.

— — hairs, ii. 565.

— — phyllotaxis, i. 408,

—— scent, ii, 202.

Salix daphnoides, scent, ii. 202.

Salix fragilis, inflorescences, ii. 299.

—— water-absorption,from atmosphere, 1.238,

Salix grandifolia, and galls of Cecidomyia

rosaria, ii. 546.

— — and galls of Hormomyia Caprez, ii. 538,

— — effect of branch mutilation, ii. 516,

Salix incana, gall of Nematus peduncuili, ii.

1.

i, 729,

Salix Myrsinites, plumed seeds, ii. 857.

Salix polaris, seeds escaping, ii. 424.

Salix pruinosa, wax-like bloom, i. 462; ii. 237.

Salix purpurea, and galls of Cecidomyia
rosaria, ii. 547.

— — and galls of Nematus vesicator, ii. 533.

— — dichogamy and hybridization, ii. 314,

——experiment with partially stripped
branch, i, 480.

Salix repens, staminal change of colour, ii. 191.

Salix reticulata, leaf, section, i. 301.

Salix rubra, hybrid, hairs of, ii. 565,

Salix viminalis, dichogamy and hybridiza-
tion, ii. 314,

— — hairs, ii, 565,

| Salsify. See Tragopogon.

Salsola, dichogamy, ii. 135.

Salt, incrustations, of leaves and stems, mode
of retention, i. 237.

— in sap of succulents, i. 329.

Saltness of water, and blueness, i. 389.

Salvia, direction of flowers, ii. 225.

— hairiness, i. 317.

— hybrids, ii. 585.

— pericarp mucilage, i. 615.

Salvia argentea, absorption-cells of hairs, i.
227.

Salvia betonicifolia, hybrid, ii. 585.

Salvia cardinalis, red flower, ii. 196.

Salvia cleistogama, flowers, ii. 394,

Salvia glutinosa, flower and pollen trans-

ference, ii. 262.

—— pollen-grains, ii. 98.

— — rocking connective, ii. 262.

— — sticky calyx, ii. 870.

Salvia officinalis, hammer-apparatus, ii. 263.

Salvia pratensis, hammer-apparatus, ii. 263.

Salvia splendens, coloured bracts, ii. 183,

Salvia sylvestris, hybrid, peculiarity of foli-
age, li. 576,

Salvia Verbenaca, the Wild Clary, petiole
section, i. 22.

973

Salvia verticillata, seed-dispersal, ii. 841.

Salvia viridis, alluring bracts, ii. 188.

Salvinia, protection of sporangia, ii, 13.

— sexual reproductive organs, ii, 69.

— swimming habit, i. 669. .

Salvinia natans, submerged leaves, i. 766,

Salvinia officinalis, stamen, ii. 87.

Salviniaceze, description, ii. 710,

Samara, nature of, ii. 430.

Sambucus Ebulus, scent, ii. 201,

Sambucus nigra, dates of flowering, i. 519.

—— drupe, ii. 428.

— — evergreen at Poti, i. 358,

— — reserve-buds, ii. 32.

—— scent, ii. 202,

Sambucus racemosa, anthocyanin, i. 484.

— — geitonogamy, ii. 326.

— — scent, ii. 200,

Sand, and preservation of fossil plants, ii. 612.

Sanguinaria Canadensis, latex, i. 470.

—— stamen, ii. 87.

Sanguisorba alpina, pollen discharge, ii. 145.

Sanicula Europea, winter protection, i. 550.

Santalacess, ii, 754.

— many parasitio, i. 176:

Sap, ascent of, theoretical considerations, i.
270.

— exudation in roses, maples, birches, rela-
tive volume, i. 272.

— raw, or crude, factors determining desti-
nation, i. 274,

Saponaria ocymoides, distribution of sexes,

ii. 300.

— — elevation and coloration, ii. 511.

Saponaria Vaccaria, duration of flowering,
ii, 213.

Saponaria viscosa, carnivorous in minor
degree, i. 156.

Saponin, in roots of Saponaria, i. 763.

Sapotacez, ii. 768.

Saprolegnia, ii. 671.

— offshoots, ii. 802.

Saprolegnia ferax, parasitic on salmon, ii. 671.

— parthenogenesis in, ii. 464.

— selection of host, i. 171.

Saprolegniacez, asexual and sexual repro-
duction, ii. 480.

— characters, ii. 670.

— on floating dead bodies, i. 105.

Saprophytes, absorption of carbon dioxide,
i. 63,

— absorption roots, i. 115.

— fastidiousness of, i. 118,

— favourable conditions for, i. 102.

— fossil remains, ii. 614,

— green, absorption of carbon, i. 103.

— in humus of meadows, i. 112.

— in water, i. 104.

—non-green, absorption of organic com-
pounds, i. 103.

— not sharply marked off from non-sapro-
phytes, i. 104.

— nutrition, i. 466.

— relation to decaying bodies, i. 99.

— substratum, ii. 499.

Saprophytic Bacteria, effect on substratum,
ii. 623.

Saprophytism, means of determining, i. 100.

Sarcanthus rostratus, aérial roots, i. 753.

—— strap-shaped adherent roots, i. 107.

Sarcina ventriculi, ii. 624.

Sarcophaga carnaria and flower-colour, ii.

Sarcophytaces, ii. 762.

Sarcophyte sanguinea, Cape, i. 195.

— — description, i, 196.

— — flowering axis, flowers, &c., i. 198.

Sargasso Sea, area, &c., ii. 665.

Sargassum, host for other Alge, i. 160.

Sargassum bacciferum, in Atlantic, ti. 665.

Sarothamnus, explosive flowers, ii. 267.

Sarothamnus scoparius. See Spartium sco-
parium.

Sarracenia, heteromorphic leaves, i. 130.

— storage of pollen, ii. 94.

Sarracenia Drummondii, honey, &c., i. 130.

— — pitchers and leaves, i. 130.

974

Sarracenia laciniata, pitcher, i. 127.

Sarracenia purpurea, geographical distribu-
tion, &c., i. 125.

—— pieces of pitcher, from orifice and lower
part, i. 124.

—— pistil and stamen, ii. 279.

—— scent, ii. 201.

Sarracenia variolaris, attractiveness, struc-
ture, size, &c., of pitchers, i. 128.

e— — utricle, secretion, &c., i. 127.

Satureja hortensis, adaptability, ii. 513,

— — elevation and coloration, ii. 511.

— — light and growth, ii. 508.

Saussurea alpina, scent, ii. 201.

Savory, Summer. See Satureja hortensis,

Saxifraga, bulbils, ii. 820.

— characters of hybrids, ii. 558,

— flower, monstrous, ii. 89.

— flowers, imperfect, ii. 294,

— — variability of colour, ii. 189, 569.

— honey, ii. 179.

— stolons, i, 663.

Saxifraga aizoides, absorptive cells of, i. 91.

—— fine markings and flies, ii. 191.

—— pollen-grain, ii. 100.

Saxifraga Aizoon, leaf-rosette, i. 410.

—— papilliform projections on leaves for re-
tention of lime iner ions, i. 235.

INDEX.

Scandinavian flora, autogamy in, ii. 400.

Scandix, protogynous, ii. 311.

Scandix Pecten-Veneris, flower and auto-
gamy, ii. 342.

— — — persistent cotyledons, i, 622,

Scape, nature of, i. 658.

Scarlet flowers, geographical distribution, ii.

196,

Scarlet Geranium. See Pelargonium zonale.

Scenedesmus, structure, ii. 637.

Scent, action at a distance, ii. 207.

—and specific constitution of protoplasm,
ii, 204,

— of hybrids, ii. 566.

— repellent, of stems, &c., ii. 198.

Scents, aminoid, insects attracted by, ii. 207.

— disagreeable, and seed protection, ii. 447.

— double, ii. 203.

— groups distinguished by, ii. 615.

— number, ii. 199,

— variety in a genus, &c., ii. 487.

Schistostega osmundacea, capsule, ii.479,703.

— —chlorophyll-granules, ef. Pl. I., i. 373.

— — habitat and luminosity, i. 385.

—— protonema, ii. 701.

Schizvea fistulosa, ii. 707.

— — fronds with sori, ii. 11.

Schi characteristics, ii, 708,

Saxifraga androsacea, protogynous, ii. 311.

Saxifraga bryoides, pollen deposition, ii. 277.

Saxifraga bulbifera, prey capturing, i. 155.

Saxifraga cernua, bulbils, ii. 454.

Saxifraga controversa, autogamy, ii. 337.

— — flower, ii. 236.

—— light experiments with, ii. 504.

Saxifraga flagellaris, vegetative propagation,

ii. 801.

— — with runners, ii. 801.

Saxifraga Geum, anthocyanin, i. 520.

—— pollen deposition, ii, 277.

Saxifraga hieracifolia, autogamy, ii. 379.

Saxifraga Huetiana, protection of pollen, ii.
120, 121,

Saxifraga japonica, arrangement of stomata,
i, 280.

Saxifraga juniperifolia, geitonogamy, ii. 326.

Saxifraga luteo-viridis, prey capturing, i. 155.

Saxifraga nivalis, bulbils, ii. 454.

Saxifraga oppositifolia, &c., lime incrusta-
tions, i. 71.

Saxifraga peltata, protogynous, fi, 311,

— — vernation, i. 350,

—— water-receptacles, i. 239.

Saxifraga rotundifolia, cross-fertilization, ii.

— — dichogamy, ii. 308.

Saxifraga sarmentosa, anthocyanin, i, 520.

— — procumbent, i, 661,

Saxifraga stellaris, bulbils, ii. 454,

— — green flower, ii. 86.

—-— pollen deposition, ii. 277.

Saxifraga tridactylites, anthocyanin, i. 521.

— — distribution of sexes, ii. 298,

— — prey capturing, i. 155,

— — sticky foliage, ii. 236.

Saxifragacez, autogamy in, ii, 335,

— chiefly protandrous, ii. 211.

— hybrids from extreme forms, ii. 584.

Saxifrageze, movements of stamens, ii. 250.

— lime-incrusted, habitat, i. 315.

Scabiosa, behaviour to own and foreign
pollen, ii. 407.

— hairiness, i. 317.

—protection from illegitimate removal of
honey, ii, 238,

Scabiosa cretica, hairs, i. 321.

Scabiosa graminifolia, hairs, i. 321,

— — seed-dispersal, ii. 854.

Scabiosa lucida, distribution of sexes, ii, 298.

— — periodically pendulous capitula, i. 530.

— — protection of pollen, ii. 121.

Scalariform vessel, i. 469.

Scale-leaf, food-reserve, i. 625,

Scale-leaves, and light, i, 412,

— — functions, i. 624,

— — of tubers, i. 651.

— — on aérial buds, i. 626,

Schizanthus primatus, explosive distribution
of pollen, ii. 266.

Schizocarp, nature of, ii. 429.

Schizocarps, ii. 427.

Schizochlamys, life-cycle, ii. 636.

Schizomycetes, application of term, i. 505.

— description, ii. 622.

Schizoneura Ulmi, gall, ii. 552.

——— on Elm leaf, ii. 533.

Schizophyceze. See also Cyanophycee.

— association with Lichens, &c., ii. 622.

Schizophyta, characteristics, ii. 620.

Schleiden, description of sea depths, i. 388.

Schnittspahns, and origin of Cytisus Adami,
ii. 570.

Schrankia, fruit protection, ii. 445.

Schrankia aculeata, leaf, diurnal positions,
i. 534,

Schwendenerian theory of Lichens, ii. 692.

Sciadium, life-cycle, ii. 639.

Sciadopithys verticillata, Japan, ii. 725.

Scientia amabilis, i. 7.

Scilla bifolia, flower colour and surround-
ings, ii, 194.

Scilla Sibirica, duration of flowering, ii, 213.

Scirpus, cleistogamy, ii. 392,

Scirpus itosus, hanical ti
ment, i. 731.

Scirpus lacustris, height, ii. 746.

— — protection of stomata from moisture, i.

294.

Scitaminez, distinctive characters, ii. 734,

— venation, i. 634.

Sclerotinia, characteristics, ii. 682.

Sclerotium, of Agaricinez, ii, 689.

— of Claviceps, ii. 680.

Scolopendrium hybridum, hybrid, ii. 582.

Scolopendrium officinarum and Ceterach
officinarum, hybrid of, ii. 482.

Scopolia, cross-fertilization, ii. 305.

Scorodosma Asa foetida, germination, i. 611.

Scorpioid cyme, i. 738,

Scorpiurus sulcata, hooked fruit, ii. 8'73.

Screw Pine. See Pandanus utilis.

Scroll-gall of Rhododendron ferrugineum,
section, ii. 531.

Scrophularia, cross-fertilization, ii, 305,

— honey, ii. 179.

— nectary, ii. 175.

— protogynous, ii. 311,

Scrophulariaceze, ii. 771,

— cross-fertilization in, ii, 301,

— hybrids among, ii. 585,

Scrub, type of community, ii. 887, 892,

Scurvy-grass, See also Cochlearia,

— — anther, ii. 90.

Scutellaria, seed-dispersal, ii. 842.

Scutellum of Graminee, structure, &c., i. 604,

— of Wheat, i. 599.

Scybaliaceze, ii. 762. P 2

Scybalium fungiforme, intimate connection
with host, &c., i. 189. 7

Scytonema, Alga of forms of Cora, ii. 695.

Sea, vertical limits of vegetation, i. 387.

Sea-anemones, symbiosis with plants, i. 254.

Sea-breeze and dispersion of pollen, ii. 134.

Sea-buckthorn. See Hippophae rhamnoides.

Sea-grass. See Zostera marina.

Sea Lavender. See Statice.

Sea-lettuce. See Ulva latissima.

Sea-phosphorescence and Dinoflagellata, ii.
625.

Season, and colour of flowers, ii. 197.

Sea-water, rich in organic substances, i. 104.

Sea-weeds, dispersal of offshoots, ii. 808,

—— Red and Brown, non-parasitic thougb

frequently epiphytic, i. 160.

Sea-wracks, fossil remains, ii, 614,

—— length, i. 388,

—— luminosity, i. 388.

Sebastiana Pavoniana, hopping fruit, ii. 844.

Secale cereale and Ergot, ii 681.

— — pollination, ii. 142.

Secretion, acid, of Cephalotus pitchers, i. 131.

— in pitchers of Darlingtonia and Sarracenia
variolaris, i, 129.

— of Dionza glands, i. 149.

— of Drosophyllum glands, i. 154.

— of Pinguicula glands, i. 142.

— of pitchers, i. 128.

— properties of, in Nepenthes pitcher, i. 135.

— viscid, not necessarily digestive, i. 156.

Sedum, cylindrical leaves, i. 327.

Sedum acre, elevation and coloration, ii. 511.

Sedum album, aqueous tissue, i. 328.

— — elevation and coloration, ii. 511.

Sedum annuum, formation of offshoot, ii. 452.

Sedum atratum, anthocyanin, i. 522.

— — autogamy, ii. 344.

— — duration of flowering, ii. 213.

— — nectaries, ii, 175.

Sedum dasyphyllum, aqueous tissue, i. 328.

—— autogamy, ii. 344.

— — offshoots, ii. 822.

Sedum glaucum, aqueous tissue, i. 328.

— — formation of offshoots, ii. 452.

Sedum refiexum, position of root-hairs in
suspended shoot, i. 89.

Sedum Rhodiola, cold resistance, i. 543.

Sedum sexangulare, elevation and colora-
tion, ii. 511.

Sedum Telephium, aqueous tissue, i. 328

— — roots, i. 760.

Sedum villosum, carnivorous in minor degree,

i. 156.

— — sticky foliage, ii. 236.

Seed, centre of gravity and position, ii, 426.

— dispersal by wind, ii. 447.

— of Gourd, germination, i. 610.

— of Taxus, ii. 442.

— water-absorption, ii. 425,

Seed-buds, meaning, ii. 84.

Seed-coat, functions, i. 601; ii, 450.

—— structure, ii. 424.

Seed-dispersal, ii. 833,

——and Ants, ii. 866,

—— and colour, ii. 865,

— — general observations, ii. 877.

— — limits of, ii. 879.

Seed-leaf. See Cotyledon.

Seedling and nocturnal radiation, i. 538,

— of Nepenthes, i. 132.

—of Orobanck growth, attach to
host, &o., i. 184,
— of Rhizophora, detach tandsubsequent

development, i. 603,

— respiration, i, 494.

Seedlings, i. 599.

— dicotyledonous and monocotyledonous, i,
607.

— of Beech and Fir, impossibility of rearing
in culture solutions, i. 251.

— of parasitic plants, i. 173.

Seeds, appendages, ii. 423.

— ash proportion, i. 66,

— chlorophyll in, i. 376,

Seeds, cold resistance, i. 544,

— defensive arrangements, ii, 442,

— dimensions of, ii, 839,

— dispersal by birds, ii. 444,

— germinating, i. 607.

— — force of, i, 516.

— — temperatures, i. 557; ii, 488,

— heat resistance, i. 555.

— lightness of, ii, 851.

— number produced, ii. 878,

— of Conifers, ii. 442, 443,

—— dispersal, ii. 439.

—of Orchids, structure, &c., i. 377.

— of parasites, germination, i. 171.

— propagation of hybrids by, ii. 556,

— protection against wet, ii. 448.

— resting of, i, 563.

— rugged, fixation, i. 616.

— size and weight, ii. 451.

— vitality of, i. 51.

— with reserve-tissue, ii, 422.

Selaginella, characteristics, ii. 477.

—chlorophyll-granules, i. 373.

— general structure, ii. 715.

— sexual reproductive organs, ii. 69.

Selaginella Helvetica, inequality of leaves,

i, 422.

—— leaf-mosaic, i. 421.

Selaginella selaginoides, British, ii. 715.

Selaginellaces, description, ii. 715.

Selection, natural, theory of, ii. 600.

Self-fertilization and dichogamy, ii, 314.

—— of flowers, ii. 291.

Self-pollination, occurrence, ii. 331.

Semi-shrubs, spines of, i. 444.

Sempervivum, and animals, i. 432.

— leaf-rosettes, i. 410,

— stolons, i. 663.

Sempervivum hirtum, attacked by Eudo-
phyllum Sempervivi, ii. 523.

Sempervivum montanum, autogamy, ii, 344,

—— cold resistance, i. 543.

—— prey capturing, i. 155.

— — sticky foliage, ii. 236.

Sempervivum soboliferum, vegetative propa-
gation, ii. 821.

Sempervivum tectorum, stomata, i. 280.

Sempervivum Wulfenii, cold resistance, i, 543.

Senecio erucefolius, cotyledons, i. 621.

Senecio nemorensis and 8. nebrodensis,
anthocyanin, i. 520.

Senecio viscosus, florets and autogamy, ii. 363.

Senecio vulgaris, effect of dry soil, ii. 500.

—— light and growth, ii. 508.

—— pericarp mucilage, i. 615.

—— seed-dispersal, ii. 857.

Sensation, in plants, i. 53.

Sensitive plants, i. 535.

— and nocturnal radiation, i. 530.

— change of colour and function, i. 376.

Separation-layer, formation, i. 359.

Sequoia gigantea, ii. 725.

—— dimensions, i. 722.

Serjania, extra-axillary buds, ii. 28.

Serjania gramatophora, branch - tendrils, i.
693, 694,

Serratula lycopifolia, protection by Ants from
Beetle, ii. 242.

Sesleria, leaf-folding, i. 340.

Sesleria coerulea, ring formation, ii, 792.

Sesleria tenuifolia, leaf, section, i. 341.

Setaria Italica, pollination, ii. 142.

Setaria verticillata, hooked fruit, ii. 871.

Sexual and asexual generations, mutual re-
lations, ii. 474.

Sexual System of classification, ii. 601.

Seychelles Palm. See Lodoicea Sechellarum.

Shade, effect on growth of plants, ii, 506,

Shepherd's Purse. See Capsella Bursa-
pastoris,

Shoot, acropetal development, i. 396,

— morphological value, i. 333.

Shoot-apices of Rotangs, i. 676.

Shoots, asexual, dissimilarity, ii, 471.

— epiphyllous, ii. 37.

— reserve, leaf characteristics, ii, 516.

— spinose, i, 443,

INDEX,

shoots underground, important function, i.

Shore Pine, See Pinus Halepensis,

Shrubs, foliage-leaves and rain, i. 93,

Sibbaldia, dehiscence of pollen-sacs, ii. 92.

— honey, ii. 173,

Sibbaldia procumbens, habit, i. 662.

— — stamen, ii. 91.

Siberian Crab. See Pyrus salicifolia.

Sideritis Romana, colour-contrast in flower,

ii, 191,

Sideritis scordioides, pollen-grains, ii. 99,

Sieve-plates, i. 469,

Sieve-tube, i. 469.

— — of Macrocystis, ii. 663,

— — of Nereocystis, ii. 663,

Sigillariacez, characteristics, ii, 716.

Signatures, doctrine of, i. 2.

Silene and Lychnis, pollen-grains, ii. 99.

— pollination experiments, ii. 404.

Silene acaulis, distribution of sexes, ii. 300.

— — vertical range, ii. 750.

Silene conica, autogamy, ii. 336,

Silene Elizabethe, and humble-bees, ii, 239.

Silene longiflora, and night visitors, ii. 196.

Silene noctifiora, behaviour to own and
foreign pollen, ii. 407.

—— opening of flower, ii. 212.

— — weather and autogamy, ii. 391.

Silene nutans, and night visitors, ii, 196.

— — capsules in dry and wet weather, ii. 448.

— — closed flowers, ii. 154.

— — distribution of sexes, ii. 300.

— — double protection of honey, ii. 242,

—— open flowers, ii. 155.

— — pollination, ii, 154,

—— scent, ii. 201.

—— seed protection and dispersal, ii. 447.

Silene Saxifraga, and night visitors, ii. 196,

— — cross-fertilization, ii. 307.

— — opening of flower, ii, 212.

Silene Vallesia, opening of flower, ii. 212.

Siiene vespertina, opening of flower, ii. 212. ’

Silene viscosa, carnivorous in minor degree,

i, 156.

Siler, geitonogamy, ii. 324.

Silica, in cell-wall of Diatoms, ii, 625.

— in Equisetum, ii. 712.

— in hairs of Rochea, i. 325,

Siliceous marl, composed of Diatoms, ii. 627.
Silicic acid, in Diatom frustules though no
trace in aqueous habitat, i. 70.

— — accumulation through plants, i. 261.

— — occurrence in plants, i. 67.

Silicification, and animals, i. 432.

— and preservation of fossil plants, ii. 612.

— of hairs, i, 441.

Silicon, in ash of plant, i. 66.

Siliqua, morphology, ii. 432.

Silk-worms, attacked by a Cordyceps, i. 168.

Silky hairs, i. 320. ‘

Silphium laciniatum, a ‘‘compass plant”, i.
337.

Silphium perfoliatum, mechanical tissue

arrangement, i. '731.

—— water-receptacles, i. 239; ii. 234,

Silver Fir. See Abies pectinata.

Silver Tree. See Leucadendron argenteum.

Silybum Marianum, method of water-con-
duction, i. 98.

Sinapis, pollen-grain, ii. 100.

Sinapis arvensis, autogamy, ii. 348.

— — duration of flowering, ii. 213.

Sinkers, of Mistletoe, i. 209.

Siphonacez, fertilization and fruit-forma-
tion, ii. 53.

Siphones, description, ii. 641.

— differentiation of thallus, ii. 620.

Sisymbrium Thalianum, protection of pollen,
ii. 121.

Sisyrinchium, nectary, ii. 176. u

Sisyrinchium anceps, colour-contrast in

flower, ii. 190.

— — weather and autogamy, ii. 391.

Skatol, nature of, ii. 199.

Skin-diseases, due to Fungi, i. 168.

Skull-cap. See Scutellaria.

975

Slate-rocks, humus on, ii. 499.

Sleep, of plants, i. 534.

Slime-fungi. See Myxomycetes.

Sling-fruits, ii, 833.

Slips, impossibility of propagating certain
plants by, i. 250.

Sloe. See Prunus spinosa.

Slugs, protection against, ii. 238,

Smell, sense of, ii. 204.

— — and poisonous plants, i. 432.

Smilacinez, phylloclades, i. 649.

— pollen-grains, ii. 99.

Smilacoidex, characteristic, ii. 732.

Smilax aspera, stipular tendrils, i. 690.

Smithia sensitiva, and rain, i. 537.

Smyrnium, coloured bracts, ii. 183.

Snails, as lime-accumulators in top layers of
soil, i. 259.

— elevation and coloration, ii. 511.

— protection against, ii. 237.

Snake-root. See Calla palustris.

Snow, as preservative agency, i. 262.

— dust-collector, i. 80.

— effect on foliage, i. 358.

— melting by developing flower-buds, i. 498.

— protection of plants, i. 548.

Snowdrop. See Galanthus nivalis.

Snow-fall and elevation, i. 523.

Snow pressure and growth, i. 523.

Sodium, in ash of plants, i. 66.

— in marine plants, i. 68.

— phosphate, as food-salt, i. 67.

—salts of, accumulation through plants, i.
261.

Soil and specific differences, experiments, ii.
496.

— changes, in, due to nutrition of plants,
i. 257 et seq.

— clay, conditions of growth on, ii. 500.

— effect on flowering, i. 9.

— factors determining nutrition, i. 102.

— on trees, i, 106.

— retention of water, ii. 499.

— sandy, conditions of growth on, ii. 500.

— temperature in Alps, i. 525.

Solanacez, ii. 771.

— estivation in, ii. 210.

— autogamy in, ii. 366.

— diversity of pollen protection, ii. 128.

— extra-axillary buds, ii. 28.

— nectary concealment, ii. 181.

Solanum Dulcamara, berry, ii. 427.

— — colour-contrast of flowers, ii. 189.

— — twining, i. 689.

Solanum Lycopersicum, anther, ii. 90.

— — movements of cotyledons, i. 532.

——stamen, ii. 91.

Solanum sisymbrifolium, fruit protection,
ii. 445.

Solanum sodomzeum, fruit protection, ii. 445.

Solanum tuberosum, autogamy, ii. 371.

—— colour-contrast of flower, ii. 189.

—— crystalloids and starch grains, i. 457.

—— diminished fruit formation, ii. 459.

— — protection of pollen, ii. 120, 128,

—— tuber, i. 651.

—— young fruit, ii. '73.

Soldanella, autogamy, ii. 333.

— honey concealment, ii. 180.

— hybrids, ii. 585.

— melting of snow by, i. 498.

— pollen-sprinkling apparatus, ii. 275.

— protection of pollen, ii. 118.

— sub-glacial blossoming, i. 499.

Soldanella alpina, flower, ii. 180, 275.

—— corolla and autogamy, ii. 368,

— — pollen-sprinkling apparatus, ii, 275.

— — stamen, ii. 87.

Soldanella montana, anthocyanin, i. 520.

Solfatara, Naples, and Alge, i. 554.

Sonchus arvensis, latitude and closing, ii

218.

— — protection of pollen, ii. 127.

Sonchus servicornus, spinosity, i. 444.

Sophora alopecuroides, leaf, diurnal posi-
tions, i. 534.

Sorbus, deciduous protective hairs, i. 354.

976

Sorbus aucuparia, bud-scales, i. 626.

— — Gymnosporangium gall, ii. 520.

Soredia, of Lichens, ii. 24, 693, 816,

Sori, of Ferns, ii. 11.

Sorus, nature of, ii. 10.

Sow-thistle. See Mulgedium.

Spaces, intercellular, i. 27, 63.

Spadiciflore, floral characters, ii. 740.

Spadix, of Arum maculatun, ii. 742.

Spangle-galls on Oak-leaves, ii. 537, 541.

Spanish flora, general grayness of, i. 317,

Sparganaces, ii. 745.

Sparganium, monescious, ii, 297.

— pollination, ii. 136.

— protogynous, ii. 312.

Sparmannia Africana, protection of pollen,
ii. 119.

Spartium, insect reception, ii. 228.

— protective coat of wax, i. 292.

— stomata, i. 331.

Spartium junceum, scent, ii. 201.

Spartium scoparium and Xylocopa violacea,

ii. 267.
—— flower and explosive distribution of
pollen, ii. 266.

—— green tissue, relative position, i. 471.

— — inflorescence, ii. 267.

— — reserve-buds, ii. 31.

Spathe, application of term, i. 641.

Spathegaster baccarum, gall on male catkins
of Oak, ii. 526.

Spathegaster tricolor, galls on the leaves of
Turkey Oak, ii. 537.

Spathularia flavida, fairy rings, ii. '791.

Spawn, of Mushroom, a mycelium, i. 100.

Species, essential feature, ii. 581.

— extinction by Humble-bees, ii. 239.

— extinction of, ii. 899.

— fertilization and origin of, i. 594.

— of flowering plants, number, ii. 604.

— origin of, ii. 486.

Specific constancy in offshoots, ii. 494.

— constitution, of plants, i. 567.

Spectrum, absorption, of chlorophyll, i. 372.

Specularia, colour of flowers, ii. 183.

— opening and closing, ii. 116.

Specularia speculum, protection of pollen,
ii, 128.

Spergula arvensis, autogamy, ii. 338.

—— weather and autogamy, ii. 391.

Spermatogenesis, in Ferns, ii. 67.

Spermatoplasm, influence on ovary, ii. 551.

— manifold differentiation, ii. 48.

— nature of, ii. 46.

Spermatozoid, nature of, ii. 48.

— of Chara fragilis, ii. 660.

— of Chlorophycee, ii. 628.

— of Coleochezte, ii, 653.

— of Dudresnaya, ii. 53.

— of Fern, escape, ii. ‘708.

— of Fucus vesiculosus, ii. 664.

— of Selaginella, ii. 715.

— of Volvox aureus, ii. 635.

Sphacelariacee, structure, &., ii. 661,

Spherella Butschlii, eye-spot, ii. 631.

Spheerella nivalis, discovery of, i. 38.

— — hematochrome, ii. 631.

— — killing degree of cold, i. 542.

Spheerella pluvialis, description, ii. 630.

— — habitat and food, i. 108.

—— sociability of swarm-spores, i. 584,

= — swarm-cells and light, i. 383.

Spherobolus, spore-dispersal, ii. 825.

Spheroplea, life-history, ii. 652.

Spherotheca Castagnei, fruits, ii. 60,

—— on Humulus, ii. 677.

Spherotilus thermalis, and heat, i. 554.

Sphagnacez, appearance, i. 219.

— description, ii. 699.

— leaves, minute structure i. 219.

— — water-absorption, i. 219.

Sphagnum cymbifolium, sporogonium, ii,

15.
Sphere crystals, i. 457.
Spiders, elevation and coloration, ii. 511.
Spiderwort. See Tradescantia.
Spindle, nuclear, i. 581.

INDEX.

Spines, arrangement in Cactiform plants, i.
446.

—as ‘‘path-finders ”, ii. 238.

— proof of protective nature, i. 436.

— transformed shoots, i. 443.

— used as needles, i. 434.

Spireea, weaving stem, i. 672.

Spireea Aruncus, distribution of sexes, ii. 300.

— — separation-layers, i. 360.

Spirea chamzdrifolia, scent, ii. 200.

Spireea crenata, reserve-buds, ii. 33.

Spirea Filipendula, roots, i. 760.

Spirzea ulmifolia, scent, ii. 200.

Spiral, genetic, i. 398, 403.

— phyllotaxis, plans, i. 400.

Spiranthes, cohering pollen-grains, ii. 97.

Spirochzte cholere asiatice, ii, 624.

Spirogyra, chlorophyll bodies, cf. Pl. I., i. 373.

— formation of zygote, ii. 657.

— occurrence, ii, 654,

Spirogyra-filament, structure, ii. 656.

Spirogyracee, ii. 654.

Spirophyton, ii. 610. ,

Splachnacez, true saprophytes, i. 103.

Splachnum, apophysis, ii. 702.

— saprophytic, ii. 704.

Splachnum ampullaceum, capsule, ii. 703.

— — saprophytic on dung of cattle, i. 103.

Splachnum luteum, capsule, ii. 703.

Sponge, symbiosis with Chlorophycee, ii. 627.

Spongy parenchyma, functions, i. 473,

— — chlorophyll-granules, i. 374.

—— movements of chlorophyll-granules, i.

381.
Spongy tissue, of leaves, chief function, i.

279.

Sporangiole, of Cheetocladium, ii. 673. -

— of Thamnidiun, ii. 673.

Sporangium, nature of, ii. 10.

— of Ferns, ii. 476.

— of Marattiaces, ii. 709,

— of Mucor, ii. 673.

— of Myxomycetes, mode of origin, ii. 619.

— of Ophioglossacez, ii. 709.

— of Polypodiacew, ii. 706.

— of Psilotum, ii. 715.

— of Schizeacez, ii. 709.

— of Tmesipteris, ii. 715.

— protection from moisture, &c., ii. 13.

Spore, of Equisetum arvense, ii. '712.

— of Lycopodium, ii. 716.

— places of origin, ii. 10.

— unicellular brood-body, ii. 6.

Spore-capsule, of Polytrichum, ii. '700.

Spore-capsules, of Mosses, ii. 703.

Spore-formation, by abstriction, ii. 20.

Spores, classification according to mode of
origin, ii. 10.

— dispersed by wind, ii. 812.

— of Fern, dispersal, &c., ii. 476.

— of Lichens, dissemination, i. 246.

— of Moss, dispersal, ii. 479.

— of Moulds, heat resistance, i. 554.

Sporocarps, of Marsilia quadrifolia, ii. '710.

— of Salvinia natans, ii. '710.

Sporodinia grandis, conjugation and fruit-
formation, ii. 53.

Sporogonium, of Bryacez, ii. 702.

— of Muscines, ii. 15, 477.

Sporophyte, of Hepatice, ii. 696,

— of Lycopodiales, ii. 704,

— of Phanerogamia, ii. 717.

— of Pteridophyta, characteristics, ii. 704.

— young, of Fern, ii. 708.

Spring flowers, probable reason for blue
colour, ii. 194.

Sprinkling apparatus for pollen transfer, ii.
273, 275. J

“Sprouting” of Rye, &c., ii. 454.

Spruce-fir Aphis. See Chermes abietis.

Spumaria alba, sporangia, ii. 491.

Spur, of Orchids, and honey, ii. 176.

Spurge. See Euphorvia.

Spurge-family. See Euphorbiaceae.

Spurge-laurel. See Daphne Laureola.

Spurges, of Mediterranean, waxy bloom of
leaves, i. 312.

Squirrels, disperse fruits, ii. 866.

Squirting Cucumber, ii. 834.

Stachys, hybrids, ii. 585.

Stalk, of ovule, i. 644.

Stamen, morphological value of parts, ii. 88.

— parts of, i. 642.

Stamens, ii. 87.

— arrangement, i. 641; ii. 85.

— as insect platform, ii. 225.

— constancy in number, ii. 86.

— division of labour, i. 645.

— metamorphosis, i. 646.

— of monstrous flowers, ii. 86.

Staminal filaments, turgidity in Grasses, ii.
140.

Staminiferous buds, of Vallisneria, ii. 105.

Staminode, application of term, i. 647.

Standard, of papilionaceous flower, ii. 228.

Stanhopea, duration of flowers, ii. 214.

— edible fleshy growths, ii. 170.

Stanhopea Devoniensis, Pl. XIII.

Stanhopea tigrina, opening of flowers, ii. 212.

Stapelia, colour and odour, ii. 197.

Star Anise. See Iilicium anisatum.

Starch, conducting tissues for, i. 480.

— decomposition by diastase, i. 465.

— formed by protoplasts, i. 61.

— percentage composition, i. 454.

— storing, i. 358.

Starch-grains, of plant hybrids, ii. 566.

— — various forms, i. 459.

Starch-granules, in endosperm, ii. 421.

Starch-stars, of Chara stelligera, ii. 661.

Star of Bethlehem. See Ornithogalum.

Statice, anthocyanin, i, 484.

— pollen-grain, ii. 100.

— salt on leaves and stems, i. 236.

Staurospermum, conjugation, ii. 658.

Stearin, in cuticle, i. 309. ”

Stellaria, massing of flowers, ii. 186.

Stellaria bulbosa, geographical restriction, ii.

2.

— — vegetative propagation, ii. 463.

Stellaria graminea, protection of pollen, ii.120.

Stellaria Holostea, autogamy, ii. 355.

Stellaria media, abortive anthers, ii. 294.

— — autogamy, ii. 338,

—— hairs on stem and petioles, i. 227.

— — movements of cotyledons, i. 532.

Stellatz, source of name, i. 637.

Stellate hairs, classificatory value, ii. 564.

Stellera passerina, effect of mutilation, ii. 517.

—— weathér and autogamy, ii. 391.

Stem, classification, i. 650.

— creeping, i. 652, 662.

— floating, characteristics, i. 665.

— foliage bearing, i. 655.

— geometrical arrangement of cells and
leaves, i. 405.

— grooving of, for water conduction, i. 95,

— lattice-form, i. 678.

— mode of climbing, i. 671, 686.

— morphological considerations, i. 648.

— nodes and internodes, i. 396.

— procumbent, mechanical tissue, i. '735.

— prostrate, i. 662.

— scaly, i. 651.

— subterranean, mechanical tissue, i. 735.

— tendril-bearing, i. 689.

— transverse and longitudinal sect. i. 469.

— weaving, nature of, i. 671.

— woody, i. 657.

Stemonitis fusca, sporangia, ii. 491.

Stephanospheera, structure, ii. 631.

Steppe-antelope, eastward retreat, ii. 462.

Steppe-fauna, eastward retreat, ii. 462.

Steppe-flora, eastward retreat, ii. 462.

—— previously in Central Europe, ii. 903.

Steppe-insects, probable eastward retreat, ii.
462,

Steppe-plants, &c., coloured stamen-fila-
ments in, ii. 183,

— — covered by glandular viscid hairs, i. 230.

— — reserve-buds, ii. 33.

— — seed protection, ii. 450.

— — sticky foliage in, ii. 236.

Steppe-porcupine, eastward retreat, ii. 462.

Steppe-witches, ii. 850.

Sterculiacew, seed-dispersal, ii. 837.
Stereum, texture and hymenium, ii. 688.
Sterigmata, of Basidiomycetes, ii. 20.
Sterility of plants under cultivation, ii. 402,
sil protection of pollen from rain,

Sternbergia lutea, autogamy, ii, 373.
Sticky bristles, and protection of flowers, ii,

237,

— fruits, ii, 869.

— secretions, and protection from marauders,
ii, 234,

Stigeoclonium, thallus, ii. 652.

oer adaptation to wind-pollination, ii.

—and wind-fertilization, ii. 134.

— as pollen-protector, ii. 111.

— attraction for pollen-tubes, ii, 413,

— changes after pollination, ii. 285,

— morphology, i. 645.

— pollen selection, ii, 404.

— sticky, ii. 282.

Stigmaria, nature of, ii. 716.

Stigmas and stamens of Iris, ii. '729.

Stigmatic chambers, of Asclepiads, ii. 259,

Stilt-roots, i. 758, 759.

— — Structure, i. 761.

Stimuli, acting on roots, i. 776.

Stimulus, propagation of, i. 151.

— transmission in sensitive plants, &c., i, 536.

Stinging Nettle. See Urtica dioica.

Stipa, fruit anchoring, i. 616.

Stipa capillata, folding of leaf, i. 344.

— — leaf, section, i. 342.

Stipa pennata, Pl. VI.

—— awn functions, i. 617.

— — dispersal, i. 617.

— — fruits boring into ground, i. 619.

— — isolated colonies, i. 528.

Stipular nectaries, ii. 232.

— spines, i. 448. .

Stipules, chief function, i. 637.

— chlorophyll protecting, i. 392.

— deciduous, i, 351.

— of Leguminose, i. 448.

— of Marattiacez, ii. 709.

— protective, i. 351.

Stipule-tendril, i. 692.

Stock. See Matthiola.

Stock, relation of graft to, ii. 571.

— wild, in grafting, i. 214,

Stolon, nature of, i. 663.

Stoma, description of, i. 63.

Stomata, and diurnal positions of leaves, i.
535.

— and honey secretion, ii. 172.

—and transmission of carbonic acid, i. 370.

— and water-pores, i. 366.

— arrangement in switch-plants, i. 332.

— exudation of saline solution from, i. 236.

— functions, opening and closing of, guard-
cells, i. 308.

— in pit-like depressions, i. 298.

—in the furrows of green stems, i. 299.

—of Knightia excelsa, ii. 751.

— of Moss capsule, ii. 702.

— over-arched, of Australian Proteaces, i.
297.

— protection from moisture by cuticular pegs,
i, 294, 296.

— protection from moisture by papilla-like
outgrowths, i. 295.

—protection from moisture by rolling of
leaves, i. 302.

— protection from wetting, i. 292.

— regulators of transpiration, i. 309.

— shape when open, size, i. 281.

— surface view and section, i. 294.

— within hollow tubercles, i. 300.

Stomate, of Marchantia, ii. 697.

Stomates, in Anthocerotacex, ii. 698.

Stonecrop. See Sedum.

Stone-fruit, ii. 428.

Stone Pine. See Pinus Pinea.

Storage of pollen, ii. 94.

Storm, effect on vegetation, i. 474,

Vou. ITI.

INDEX.

Stratificati See Cell-wail.
Stratiotes, protective isolation by water, ii.
234,

Stratiotes aloides, mode of life, i. 76.

—— roots, i. 752.

— — spiny leaves, i. 438.

— — winter sinking, i. 552,

Strawberry, Wild. See Fragaria vesca,

Strawberry-tree. See Arbutus Unedo.

Strelitzia, 8, African, ii, 734.

Streptocarpus polyanthus, cotyledons, un-
equal development, i, 622.

Striation, cause of, i. 569.

Stroma-starch of Hydrodictyon, ii. 640.

Struggle for existence, ii. 600.

Struthiopteris germanica, height, i. 714.

Struvea delicatula, habitat, ii. 646.

Style, attraction for pollen-tubes, ii. 414.

— morphology, i. 644.

— movements of, ii. 277.

Stylidiacess, ii. 767.

Styphnolobium japonicum, green cotyledons,
ii, 421.

Sub-alpine plants, autogamy in, ii. 400.

Suberin, chief component of cuticle, com-
position, i. 309,

— formation, i. 458.

Substance, intercellular, i. 26.

Sut ‘buds, charact: ics, ti. 34,
Suk ion and plant ii. 498.

Substratum, classification of plants accord-
ing to, ii, 496.

— effects of Bacteria on, ii. 623.

— influence on graft, ii. 571.

Subterranean fruits, ii. 878.

— roots, mechanical adaptation, i. 762.

Subularia aquatica, sub-aqueous fertilization,
ii, 391.

Succulent fruits, dispersal, ii. 864.

— plants, i. 327.

Succulents, compared to camels, i. 328.

— heat resistance, i. 554.

— not eaten by animals, i. 432.

— water-retaining substances in juices, i. 329.

Suckers, of Bartsia alpina, i. 180.

— of Lathra, i. 182.

— of Pedicularis, i. 179.

— of Rhinanthacez, i. 178.

Sugar, formed by protoplasts, i. 61.

— from formic aldehyde, i. 456.

— manufacturing of, i. 377.

— storing, i. 358.

— viscous fermentation, i. 506,

Sugars, conducting tisues for, i. 479.

— importance, i. 463.

Sugar solution and germination of pollen-
grains, ii. 407.

Sulphur, sources of, i. 458.

— necessary for proteid formation, i, 67.

Sulphur Bacteria, ii. 624.

Sulphuric acid, reduction, i. 458.

Sulphurous rain, ii. 151.

Sumachs. See Rhus Cotinus and R. Ty-
phinum.

Summer sleep, of plants, i. 356.

Suv-birds, pollen transference by, ii. 247.

Sun-dew. See Drosera.

Sunlight, and respiration, i. 496.

Sunshine, and flowering, ii. 474.

—and opening of flowers, ii, 219.

Suspensor, of embryo, ii. 421.

—— in Gymnosperms, ii. 438.

— of Selaginella, ii. 715.

Swammerdam, Dutch philosopher, i. 21.

Swarm-spores, behaviour towards light, i, 382.

— — in Chytridiacez, ii. 669.

— — in Saprolegniacew, ii. 669.

— — of Peronospores, ii. 57.

Sweeping-hairs of style, ii. 318.

Sweet Flag. See Acorus Calamus,

Sweet-sop. See Anona squamosa.

Sweet Vernal Grass. See Anthorwanthum.

Swertia, nectaries, ii. 178.

Swertia perennis, autogamy, ii. 341.

—— honey protection, ii, 241.

Swietenia Mahagoni, flower, ii. 285.

Swimming plants, characteristics, i. 669.

977

Switch-plants, chlorenchyma, i. 331.

— — green tissue, relative position, i. 471.

— — strengthening tissues, i. 426.

Switch-shrub, stem in section, i, 332.

Sycamore. See Acer Pseudo-platanus,

Symbiosis, and evolution, ii. 610.

— and nutrition, i. 466.

— case allied to that of Lichens, i. 268.

— essential conditions, of Lichens, i. 244.

— general considerations, i. 243.

— of Bacteria with root-fibres, ii. 521.

—of fungal hyphz with roots of Phanero-
gams, in relation to cultivation, i. 250.

— of Liverworts and Rotifere, i. 255.

— of plant and animal, i. 254.

— of plants with Ants, ii, 233.

— of Yucca with Moths, ii. 159.

Symphyogyna, vascular system, ii. 699.

Symphytum, bristles, i. 441.

— pollen-grains, ii. 97.

— unfolding of inflorescence, i. 744.

Symphytum officinale, pollen - sprinkling
apparatus, ii. 275.

Sympbytum Tauricum, floral change of
colour, ii. 191.

Synchitrium Anemones, &c., gall formation,
ii, 520.

Synconium, of Ficus, ii. 15'7.

Synedra Ulna, ii. 626.

Synergide, of egg-apparatus, ii. 81, 416.

Synthesis, of Lichen, ii. 692.

— in plants, hypotheses regarding, i. 378.

Syringa, autogamy, ii. 334.

Syringa vulgaris, hermaphrodite, ii. 296.

—— pollen-graing, ii. 97.

—— scent, ii. 201.

—— ‘Witches’ Broom” galls, ii. 548.

Syrrhopodon scaber, thallidia, ii. 23.

System, Linnean, i. 6; ii. 288.

— natural, of classification, ii. 602.

Syzygites, parthenogenesis, ii. 464.

Es .

Table Mountain, vegetation of, i. 306.

Table of Bentham and Hooker's main divi-
sions, ii. 604.

— of Braun’s classification, ii. 605.

— of De Candolle’s classification, ii. 603.

— of Endlicher’s classification, ii. 604.

— of Jussieu’s classification, ii. 602.

— of Linnzus’s classification, ii. 288.

— of Sachs’s classification of Thallophytes, ii.
606.

Tables of relative growth at different eleva-
tions, ii. 509.

Talinum fruticosum, i. 327.

Talipot, size of leaf, i. 287. ;

Talipot Palm. See Corypha wmbraculifera.

Tamarindus, flower, ii. 292.

Tamariscinez, i. 198.

Tamarisks. See Tamariscinee.

Tamarix, not true manna”, ii. 812.

— reserve-buds, ii. 35.

— salt on leaves and stems, i. 236.

Tamus, mechanical tissue, i. 732.

— pollen-grains, ii. 99.

Tannin, absorption by Mildews, i. 167.

— decomposition by Aspergillus niger, i. 507.

— taste, i. 462.

Tapetal cells, of anther, ii. 94.

Taphrina carnea, blisters on birch-leaves, ii.
676.

Tap-root, i. 760.

Taraxacum, zstivation, ii. 210.

— geitonogamy, ii. 319.

— laticiferous tubes, i. 470.

— protection of pollen, ii. 114.

Taraxacum officinale, duration of blossom-

ing, ii. 218.

—— elevation and coloration, ii. 511.

— — latitude and closing, ii. 218.

—— latitude and opening, ii. 217.

— — leaves and rain conduction, i. 95.

—— plumed fruits, ii. 857.

— — pollen-grains, ii. 99.

112

978

“Tatmidlk”, preparation of, i. 143,

Taxacez, cone characters, ii. 725.

Taxodieer, ii. 725.

Taxodium distichum, diameter, i. 722.

— — knee-like roots, ii. 725.

Taxodium Mexicanum, age, i. 720.

— — dimensions, i. 722.

Taxodium mucronatum, girth, i. 657.

Taxus, dicecious, ii. 299.

— ovule, ii. 725.

— protection of pollen, ii. 117.

Taxus baccata, age, i. 720.

—— and galls of Cecidomyia Taxi, ii. 547.

— — ashanalysis of branches with leaves,i. 70.

— — dimensions, i. 722.

—— foliage and rain, i. 92.

—— mucilage drops on ovules, ii. 419.

—— pollen discharge, ii. 145.

—— seed, ii. 440.

Tea and Indian Roses, number, ii. 555.

— Mullein, preparation, i. 443.

Teasel. See Dipsacus.

Tecoma, effect of ringing, i. 481.

Tecoma radicans, climbing roots, i. 701, 702,

706, 751, 754.

—— leafless branches, i. 479.

— — propagation by root-cuttings, ii. 27.

— — stem section, i. 477.

Teesdalia, seed-cement, i. 615.

Telekia, ejection of fruits, ii. 840.

— geitonogamy, ii. 322.

Telekia speciosa, floral change of colour, ii.
191.

Telephium Imperati,cross-fertilization, ii. 308.

—— duration of flowering, ii. 213.

—— nectaries, ii. 175.

Telephorex, and Fungus of Cora, ii. 695.

— hymenium and hymenophore, ii. 688.

Telephorus, honey-sucker, ii. 179.

Teleutospore, and chlamydospore, ii. 684.

— of Rust-fungus, ii. 24,

— of Uredinez, ii. 685.

— stage, of Gymnosporangium, ii. 522.

Tellima grandiflora, calyx and autogamy, ii.
366.

Temperature, and germination of seeds, i. 557.

— and growth, i. 512.

— and habit of plants, i. 523.

— and respiration, i. 496.

— and unfolding leaf-buds, i. 538,

— minimum for plants, i. 542.

— observations, winter, i. 547.

— of soil and air in Alpine regions, i, 525.

— shade, highest, i. 556.

— within flowers, i. 500.

Tenacula, of Struvea, ii. 646.

Tendril, adhesive discs, i. 699.

— characteristics, i. 689.

— mechanical tissue, i. 733.

— petiolar, i. 691.

— spiral twist, &c., i. 698.

— stipular, i. 690.

Tendril-bearing stem, i. 689.

— —stems, classification, i. 694.

Tendril-climbers, various a i, 697.

INDEX.

Tetraphis pellucida, habitat, i. 109.

Tetraplodon angustatum, saprophytic on
dung of carnivores, i. 103.

Tetraspora, life-cycle, ii. 636.

Tetraspore, of Floridez, ii. 24.

Tetrasporex, ii. 606.

Teucrium, zestivation, ii. 211.

— hairiness, i. 317.

Teucrium flavum, seed-dispersal, ii. 841.

Teucrium montanum, and bud-galls of Lacto-
melopus Teucrii, ii. 544.

Teucrium orientale, change of position of
styles and stigmas, ii. 305.

— — inflorescence and flowers, ii. 305.

Teucrium Scordium, and bud-galls of Lacto-
melopus Teucrii, ii. 544.

Teucrium subspinosum, spinosity, i. 444.

Thalamiflorze, of De Candolle, ii. 603.

Thalamus. See Floral stem.

Thalictrum,colouredstamen-filaments, ii.183.

— geitonogamy, ii. 328.

— protection of pollen, ii. 124.

Thalictrum alpinum, pollen dispersion, ii. 143.

Thalictrum aquilegifolium, pollen discharge,
ii. 145.

Thalictrum angustifolium, ii. 145.

Thalictrum flavum, ii. 145.

Thalictrum fcetidum, pollen dispersion, ii. 143.

Thalictrum minus, pollen dispersion, ii. 143.

Thallasiophyllum clathrum, ii. 662.

Thallidia, of Hydrodictyon, ii. 24, 482.

— of Muscinee, ii. 23.

— of Pediastrum, ii. 24.

Thallophyllodea, of Braun, ii. 605.

Thallophyta, alternation of generations, ii.480.

— classification, ii. 605.

— description, ii. 619.

— subdivision of Endlicher, ii. 604.

Thallophytes, nature of, i. 592; ii. 22.

— terrestrial, absence from Paleozoic strata,
ii. 611.

Thallus, application of term, i, 592.

— nature of, ii, 619,

— of Liverworts, ii. 696.

Thamnuidium, sporangia and sporangioles, ii.

Thelebolez, ii. 674.

Theobroma Cacao, stamen, ii. 91.

Theopt Jussieui, prc tion by leaf-
cuttings, ii. 41.

Theophrastus, i. 3; ii. 1.

— applies term “Phrygian undergrowth”, i.

— plant-forms known to, ii. 600.

Thermal constants, flower-opening, foliage-
production, fruit ripening, i. 559.

—— leaf-fall, i. 560.

— — of germination, correction, i. 561.

— — of vegetation, attempt to estimate, i. 557.

Thesium, autogamy, ii. 396.

— reterostyly, ii. 302.

— wany species parasitic, i. 176.

— nectary, ii. 176.

— pollen-grains, ii, 99.

— protection of pollen, ii. 124,

Tendrils, classification, i. 692.

Tentacle, structure of, in Drosera, i. 147.

Tentacles, movements in Drosera, i. 145.

Terminology, difficulties of, i. 593.

— discussion of, ii. 3.

— of leaf, i. 627 et seq.

Termites, and dead trunks, i. 704.

Terpenes, ii. 203.

Terpenoid scents, ii. 203.

Testa, modifications of, ii. 424.

Tetanus, and stinging hairs, i. 442.

Tetractium quadricorne, fruit-protection, ii.
442

Tetragonolobus siliquosus, leaf, day andnight
positions, i. 533.

Tetraneura alba, gall on Elm-leaf, ii. 5633.

Tetraneura Ulmi, gall, ii. 552.

——— on Elm-leaf, ii, 533.

Tetrao medius, hybrid, peculiarities of, ii, 572.

Tetrao tetrix and T. Urogallus, hybrid, char-
acteristics of, ii. 572.

Tetraphis, thallidia, ii. 23.

Thesium alpinum, absorption of water
through leaf-surface, i. 230.

— — closing of anthers, ii. 125,

—— pollen-grain, ii. 100.

Thesium rostratum, pollen-grain, ii. 100.

Thickening-bands, in porous cells of Sphag-
nace, i, 219.

Thistle, Carline. See Cariina acaulis.

— spiny leaves, i. 438.

Thistle-leaves, use of term, i. 438.

Thistles, group of, i. 436.

Thladiantha dubia, seed-dispersal, ii. 836.

— — tubers, ii. 796.

Thlaspi, nectaries, ii. 175.

Thlaspi alliaceum, &c., colour-contrast in
inflorescence, ii. 192.

Thlaspi arvense, autogamy, ii. 335,

Thlaspi rotundatum, ii. 192,

Thorn-apple. See Datura Stramonium.

Three-sided apical-cell, i. 578.

Thrift. See Armeria.

Thrips, eater of pollen, ii. 167.

Thrushes, chief agent in dissemination of
Mistletoe, i. 205.

Thuidium abietinum, parthenogenesis, ii. 464,

Thuja, arrangement of scale-leaves, i. 412.

— embryo development, ii. 438.

— pollen storing and dispersion, ii. 146.

— twig, i. 410.

—winter colour, i. 485.

Thuja orientalis, branch with cones, ii, 442.

Thunbergia, effect of ringing, i. 481.

— twisting of internodes, ii. 417.

Thunbergia grandiflora, stigma, ii. 279.

Thunbergia laurifolia, stem structure, i. 477.

Thymelacez, autogamy in, ii. 365.

— nectaries, ii. 174.

— protogynous, ii. 312.

Thymus, anther, ii. 90.

— distribution of sexes, ii. 298.

— influence of gall-mites, ii. 550.

— seed-protection, ii. 446.

— twisting of internodes, i. 417.

— various species, scent of foliage, ii. 488.

Thymus citriodorus, scent, ii. 203.

Thymus montanus, scent, ii. 203.

Thymus Serpyllum, bud-galls, ii. 531, 547.

— — stamen, ii. 87.

Tilia, bark, i. 720.

— bud-scales, i. 626.

— flower, ii. 292.

— fruiting branch, ii. 426.

— hermaphrodite, ii. 296.

— hybrids in, ii. 584.

— nut, ii. 429,

— phyllotaxis, i. 399.

— scent, ii. 202.

— scent at a distance, ii. 207.

— sheltering of pollen, ii. 108.

Tilia alba, scent, ii. 202.

Tilia Americana, scent, ii. 202.

Tilia argentea, bi-coloured leaves, i. 338.

— — flower and inflorescence, i. 646.

Tilia grandifolia, age, i. 722.

—— and galls of Hormomyia Réaumuriana,

ii. 539.

— — cotyledons, i. 621.

—— diameter, i. 722.

- ical tissue arr
— — unfolding leaves, i. 351.
Tilia intermedia, seed-dispersal, ii. 854.
Tilia parvifolia, scent, ii. 202.

— — unfolding leaves, i. 351.

Tilia, ulmifolia, stamen, ii. 87.

Tillandsie, characteristics, ii. 734.

— plumed seeds escaping, ii. 862.

— protective water-receptacles, ii, 234.

Tillandsia recurva, dissemination, i. 614

Tillandsia usneoides, di ination, i. 614.

Tilletiaceze, distinctive characters, ii. 675.

Timmia Norvegica, propagation from leaves,
ii. 458.

Timothy-grass. See Phleum pratense.

Tissue, cellular, unsuitability of term, i. 27.

— mechanical, arrangement, i. 729, 730, 731.

— meristematic, i. 582.

— of plants, i. 577.

— permanent, i. 582.

— systems, sorts of, i. 589,

Tmesipteris, habit and appearance, ii. 715.

Toadfiax. See Linaria.

Toad-stools, basidia, ii. 20.

— — resemblance of Balanophoras to, i. 190.

Tobacco. See Nicotiana.

Tobacco-plant, effect of cold soil, i. 356.

Todea, aérial roots, i. 753.

Todea barbata, aérial roots, i. 714,

— — experiments with air-roots, i. 225.

Tofieldia, autogamy, ii. 334,

— equitant leaves, i. 336,

— nectaries, ii. 175.

Tolypellopsis ulvoides. See Chara Stelligera.

Tomato. See Solanum Lycopersicum.

Tommasinia verticillaris, colonies, i, 528.

Tooth-cress. See Dentaria,

Toothwort. See Lathraa Squamaria.

Torchwood. See Verbascum thapsiforme.

Torenia, pollen deposition, ii. 280.

Torilis Anthriscus, hooked fruit, ii, 871.

t, i. 729.

Tornelia fragrans=Philodendron pertusum.

— — temperature within spathe, i, 501,

Torsion, and phyllotaxis, i i, 407.

— and twining, i. 683,

— of climbing stem, i. 686.

— of fibrous strands in nutating stems, i. 683,

— of leaf-stalks, i. 417, 418.

Torus. See Floral receptacle.

Tournefort, synoptical classification, ii. 601.

Tournefortia, buds on leag- -cuttings, ii. 43.

Toxicodendron, distribution of sexes, ii. 297,

Tozzia alpina, stamen, ii. 91.

Trabecul, of Isoétes sporangia, ii, 717.

Traches, name of wood-vessels given from
erroneous view of function, i. 276.

Tracheides, function of, i. 277.

— mode of sap conduction, &e., i. 277.

— name of wood-cells given from erroneous
view of function, i. 276.

—— nature of wall, i. 277.

— of Conifers, ii. 720.

Trachyte, i. 83.

— mountains, sand at base, i. 82.

Tradescantia, absorbent cells, i. 600.

—allurement by petals, ii. 171.

— anthocyanin, i. 520.

— cotyledon in germination, i. 606.

— edible staminal hairs, ii. 170.

Tradescantia crassula, cross-fertilization, ii

308.

— — duration of blossom, ii. 214.
Tradescantia Virginica, cross-fertilization,
ii. 308.
— — duration of blossom, ii. 214,
— — germinating seed, i. 599.
— — opening and closing, ii. 212.
Tragacanth bushes. See Astragalus.
Tragacanth-shrubs, spiny, i. 435.
Tragacanthacei, geographical distribution,
habitat, spines, i. 447.
Tragopogon, estivation, ii. 210.
— capitula closing and pollination, i. 741.
— flowers after pollination, ii. 286.
— geitonogamy, ii. 319.
— laticiferous tubes, i. 470.
— time of closing, ii. 221.
Tragus. See Bock.
one Azalea. See Azalea procumbens.
ition, attacks cell-walls, i. 167.
Trametesradiciperda. SeePolyporus annosus.
Transference of pollen, by explosive appa-
ratus, ii. 265.
— — by percussive apparatus, ii. 262.
Transformation, of reserve substances, i. 601,
— progressive, by inherent forces, ii. 596.
“Transitional forms” of Viola really hybrids,
ii, 584.
Transmission of water, centrifugal, i.94. -
—— centripetal, i. 94.
Transpiration, and fall of leaf, i. 355.
—and growth, i. 513.
—and root-pressure, i. 282, 366.
tary and supr y
action of, i. 281.
— and vascular tissue, i. 347, 362.
— by cortex of stem, i. 330.
— cessation for lengthened periods, i. 304.
— conditions of, in the case of plants with
rolled leaves, i. 305.
— contrivances for aiding, in plants with
rolled leaves, i. 303.
— current, i. 274.
—— path of, i. 276.
— effect on cell-contents, general considera-
tions, i. 274.
— extent of action, i. 282.
— factors in, i. 326.
— form and position of organs of, i. 325.
— knowledge of conditions regulating, neces-
sary for cultivation, i. 310.
— leaf movements in relation to, i. 338.
— mechanism of, compared to suction-pump,
i. 281.
—necessity for diminution, in high Alpine
plants, i. 315.
— necessity for means of increasing, in float-
ing leaves, i. 288.

INDEX.

Transpiration of cladodes, i. 334,

— of Lianes, i. 347.

— protection of stomata, i. 290,

— regulation, i. 284.

— — by stomata, i. 309,

— — in deciduous leaves, i. 347.

— seasonal, i. 347.

— signification of, i. 283,

— shape in relation to, i. 327.

— substitute for, in certain plants, i, 282.

979

Trifolium, behaviour to own and foreign
pollen, ii. 407.

— corollas after fertilization, ii. 286.

— floral change of colour, ii. 191.

— insects and keel movements, ii. 252.

— leaf, diurnal positions, i. 534.

— movements of cotyledons, i. 532.

— scent, ii. 203.

Trifolium agrarium, fruit, ii. 433,

Trifolium badium, fruit, ii. 433.

Transplanting, of plants, with symbi

ii. 184.

nfl.
— — infic

mycelia, i. 250.

Transport, of food materials, i. 466.

— of water, i. 366.

Trapa, air-bladders, i. 425.

— cotyledons, ii. 421.

— floats, i. 638.

— fruit anchoring, i. 617.

— heterophyllous, i. 668.

Trapa natans, calyx and fruit, ii. 434.

— — direction of roots on germination, i. 90,

—— resting of seeds, i. 563.

Trapella sinensis, hooked fruit, ii. 872.

Traps, advantage of, i. 158,

— animal, of Dionza, i. 149.

— — of Lathrza, i. 136.

— — of Lathrea and Pinguicula, i. 137

— of Bartsia, i. 138.

— of Utricularia neglecta, i. 121.

Traveller's Joy. See Clematis.

Traveller's Tree. See Ravenala Madagas-
cariensis.

Tree, habit, i. 718.

— phylogenetic, thallophytic part, ii. 620.

“Tree coustrictors”, i. 704.

Tree-ferns, ii. 473.

—— aérial roots, i. 714, 753.

—— caudex, i. 714.

—— mode of growth, i. 659.

—— root-hairs of, i, 224.

—-— tropical, delicacy of outer wall of epi-

dermal cells in certain, i. 284.

Tree of Chastity. See Vitex Agnus-castus.

Tree of Life. See Arbor vite.

Trees, age, i. 720.

— and struggle for existence, ii. 515.

— characteristics of inflorescences, i. 745.

— tables of dimensions, i. 722.

— trimming of, on transplanting, i. 92.

— various, and cold resistance, i. 544,

Tremella mesenterica, ii. 687.

Trentepohlia, structure, ii. 652.

Trentepohlia Iolithus, scent, ii. 653.

Trentepohlia spongophila, Sumatra, and
sponge, ii. 653.

Trentepohlia umbrina, and Lichen-fungi, ii.

53

Treub, and chalazogamic fertilization, ii. 616.

Trianon, Botanic Gardens, and natural
system of classification, ii. 602.

Tribulus orientalis, spinose fruit, ii. 875.

Triceratium Favus, ii. 626.

Trichia clavata, spore-dispersal, ii. 813.

Trichoblasts, of Mangrove stilt-roots, i. 761.

Trichocline, pericarp mucilage, i. 615.

Trichocolea tomentella, stem, i. 591.

ichodesmium Ery m, and ‘Flowers

of the Sea”, ii. 621.

— — reddening of sea, i. 389.

Trichogyne, of Dudresnaya, ii. 53.

— of Floridez, ii. 60.

Trichomanes Lyallii, ii. 707.

—— fronds and sorus, ii. 11.

Trichomes, dead, restrictive of transpiration,
i. 313.

Trichophilus, in hairs of a Sloth, ii, 627, 653.

Trichophyton tonsurans, cause of Herpes, i
169.

Trichostomum tophaceum, lime-incrusted, i.
260.

Tricyrtes pilosa, flower, ii. 181.

— — flower and autogamy, ii. 351.

— — honey concealment, ii. ae.

— — nectaries, ii. 176.

Tridactylites, autogamy, ii. 331,

Trientalis Europa, difficulty of cultivation,
i. 113.

Tr

— — seed-dispersal, ii. 855.

Trifolium fragiferum, creeping stem, i. 662.

Trifolium hybridum, change of colour, ii. 191.

Trifolium nidificum, seed-dispersal, ii. 854.

Trifolium pratense, downward pull of roots,
i. 767.

Trifolium repens, antholysis, ii. 83.

—— creeping stem, i. 662.

—— shade and growth, ii. 506.

Trifolium resupinatum, scent, ii. 203.

—— scent during day, ii. 209.

Trifolium spadiceum, change of colour, ii. 192.

Trifolium stellatum, creeping fruits, ii. 843,
844,

Trifolium tomentosum, wind-dispersal, ii.
848.

Triglochin, dichogamy, ii. 135.

— dichogamy and cross-fertilization, ii. 314.

— pollen storing and dispersion, ii. 148.

Triglochin Barellieri, flower, i. 646.

Triglochin palustre, flowers, ii. 149.

— — hooked fruits, ii. 874.

Trigonella foenum-grecum, tubercles on root-
fibres, ii. 521.

Trillium, autogamy, ii. 332.

— duration of flower, ii. 214.

— protogynous, ii. 311.

Trillium grandiflorum, scent, ii. 202.

Triopteris bifurca, seed-dispersal, ii. 853.

Triopteris brachypteris, pollen-grains, ii. 99.

Trioza Rhamni, scroll-gall on Rhamnus
catharticus, ii. 531.

Tripoli, construction through plants, i. 261.

Tripoli powder, and diatoms, ii. 614.

Tritelia, pollen-grains, ii. 98.

Trithrinax aculeata, aérial root spines, i. 433.

Triticum and Adgilops, hybridization, ii. 583.

— and Elymus, hybridization, ii. 583.

— and Puccinia graminis, ii. 686.

— pollination, ii. 142.

Triticum caninum, arched leaf, i. 430.

Triticum repens, boring scale-leaves, i. 653.

Triticum vulgare, absorbent cells, i. 600.

—— grain, scutellum, &c., i. 599.

Triumfetta Plumieri, hooked fruit, ii. 873.

Trixago, pollen sprinking, ii. 272.

Trixago apula, autogamy, ii. 353.

Trollius, colour of sepals, ii. 183.

— movements of stamens, ii. 250.

— nectaries, ii. 179.

— protection of pollen from wet, ii. 109.

Trollius Europzus, effect of mutilation, ii.517.

— — flower, section, ii. 249.

—— scent, ii, 201.

— — sheltering of pollen, ii. 110.

Tropolum, cotyledons, i. 608; ii. 421.

— fading of flower, i. 743.

— leaf-stalk tendrils, i. 692.

— nectary, ii. 177.

— pollen-grains, ii. 98.

— ringed tendrils, i. 694.

— venation, i. 632.

Tropzolum majus, seedling, i. 607.

Truffie. See Tuber.

Truffle-fruit, ii. 678.

Trumpet hyphe, of Laminaria, ii. 662.

Trumpet Tree. See Catalpa syringefolia.

Tschitscherboden, interior of Istria, absence
of Heaths, i. 307.

Tsuga Douglasii, intermediate characters, fi.
125.

Tuber, morphological value, ii. 6.

— nature of, i. 651.

Tuber melanosporum, ii. 681.

Tuberacez, description, ii. 678.

Tubercle, of Phylloglossum, ii. 715.

980

Tubercles, of Orchids, with internal stomata,
double function, i. 300.

Tubercular galls, ii. 535.

Tuberculosis, bacterial origin, ii. 624.

Tubers, propagation of hybrids by, ii. 556.

— replacing flowers and fruit, ii, 460.

— resting, of desert perennials, i. 556.

Tubular floret of Composite, ii. 115.

Tufa, calcareous, formed by the action of
Mosse, i. 260.

Tulip Tree. See Liriodendron tulipifera.

Tulipa, artificially induced drooping, ii. 123.

— dispersed by roots, ii. 832.

— double flowers, ii. 80.

— forcing, i. 564.

— hybridization and flower colours, ii. 568.

— insect platform, ii. 229.

— leaves and rain conduction, i. 94.

— opening and closing, ii. 220.

— opening of flower, ii. 212.

Tulipa Didieri, cross-fertilization, ii. 307.

Tulipa Gesneriana, depth in soil and growth,
ii. 407.

Tulipa sylvestris, autogamy, ii. 379.

— — flower, part of, ii. 240.

—— protection of pollen, ii. 120.

—— scent, ii. 203.

Tulostoma mammosum, ii. 690.

Tunbridge ware and Peziza zeruginosa, ii. 682.

Tundra, the, Lichens of, i. 218.

Turgenia, protogynous, ii. 311.

T ia latifolia, y, ii, 342.

— — flowers, sexual conditions, ii. 296.

—— light and growth, ii. 508.

Turgescence, i. 277.

Turgidity, and “burning”, i. 554.

—and growth, i. 511.

— and leaf-movements, i. 532.

— and opening of flowers, ii. 219.

— and organic acids, i. 464.

— and shortening of root, i. 770.

— nature of, i. 59.

— of staminal filaments, ii. 140.

Turion, application of term, i. 624.

— scale leaves of, function, i. 625.

Turkey Oak. See Quercus Cerris.

Turnip. See Brassica Rapa rapacea,

Turpentine Gall-apple, ii. 534.

Turritis glabra, anthocyanin, i. 520.

Tussilago, distribution of sexes, ii. 297.

— geitonogamy, ii. 321.

— imperfect flowers, ii. 295.

— protection of pollen, ii. 120,

Tussilago Farfara, dichogamy, ii. 312.

—— flowering and flowerless shoots, i. 652.

— — two-coloured leaves, habitat, i. 293,

Twayblade. See Listera.

Twining, accessory aids, i. 687.

— and torsion, i. 683.

— conditions regulating, i. 682.

— independence of external conditions, i.
685.

— plants, leaf arrangement, i. 420.

— stem, mechanical tissue, i. 732.

— stems, annual and perennial, i. 688,

Tylanthus ericoides, rolled leaf, section,i. 301.

Typha, absorbent cotyledon, i. 765,

— cotyledon in germination, i. 606.

— details of germination, i. 608.

— erect leaves, i. 428.

— moneecious, ii. 297.

— protogynous, ii. 313.

— wax on leaves, i. 292.

Typha angustifolia, leaf-twist, i. 429,

Typha latifolia, cohering pollen-grains, ii. 97.

Typha Shuttleworthii, germination, i. 607.

—— cohering pollen-grains, ii. 97,

— — plumed fruits, ii. 857.

Typhaces, ii. 745.

Typhus, relapsing, germ of, i. 163.

Tyrol, Castle of Ambras, Lichens on column
near, i. 247,

— mountain pines, i. 549.

— temperature observations, i. 547.

Tyrosin, i. 263.

— an amide, i. 458.

— nature of, ii. 199.

INDEX.

U.

Udotea, thallus, ii. 645.

Ulex, explosive flowers, ii. 267.

— protection of stomata from moisture, i. 298.

Ulex Gallii, &c., fruit-protection, ii. 445.

— — spines, i. 434.

Ulmaces, ii. 758.

Ulmus, bud-scales, i. 626.

— flowering, ii. 150.

— leaf-mosaic, i. 422.

— phyllotaxis, i. 399.

— pollen discharge, ii. 145.

— protogynous, ii. 313.

— roots, i. 752.

Ulmus campestris and gall of Schizoneura

Uimi, ii. 533.

— — and gall of Tetraneura alba, ii. 533.

— — and gall of Tetraneura Ulmi, ii. 532, 533.

—— diameter, i. 722.

— — flowers and fruits, ii. 143.

—— pocket-galls on, ii. 532.

—— protogynous, ii. 311.

Ulothrix, cilia of swarming protoplast, i. 29.

— life-history, ii. 648.

— vacuole of swarm-spore, i. 31.

Ulothrix zonata, ii. 648.

— — fruit-formation, ii. 50.

Ulva, chlorophyll bodies, i. 373.

— habit, i. 587.

Ulvacez, range, i. 390.

Ulva, on Crabs, i. 77.

Ulva lactuca, best situation, i. 105.

Ulva latissima, ii. 648,

Unmbel, i. 739.

Umbelliferz, ii. 788.

— estivation in, ii. 210.

—and Field-mice, i. 763.

— anthocyanin and elevation, i. 522.

— autogamy, ii. 342.

— behaviour of cotyledons, i. 600.

— buds on hypocotyl, ii. 28.

— coloured bracts in, ii. 183.

— fleshy leaves, i. 327.

— flowers, sexual conditions in, ii. 296.

— geitonogamy in, ii. 323,

— honey, ii. 179.

— hybrids few, ii. 584.

— insect guests, ii. 230, 243.

— integument of ovule, ii. 81.

— liberation of cotyledons, i. 612.

— massing of flowers, ii. 186.

— oriental, flowering, i. 745.

— periodically pendulous umbels, i. 530.

— pollen deposition in, ii. 278.

— pollen-grains, ii. 102.

— power of crossing, ii. 616.

— protection from grazing animals, i, 451.

— — of pollen, ii. 120.

— protogyny in, ii. 311.

— scent of flowers, stem, &c., ti. 199,

— schizocarp and mericarps, ii. 430.

— seed protection from dryness, ii. 450,

— sticky stigmas in, ii. 282.

— venation, i. 632.

Uwmbilicaria, Foliose Lichen, ii. 694.

Umbrella Pine. See Sciadopithys verti-
cillata.

Unbidden guests of plants, nature of, ii. 230.

Undershrubs, characteristics of inflores-
cences, i. 745.
1 tissue arr t, i. 729.

Underwood, promotion of growth, ii. 36,

Unfolding of Beech-leaves, i. 353.

— of leaves, i. 349.

Unger, Franz, botanical observations at
Kitzbithel, ii. 495.

— history of plants, ii. 3.

— work on development and its title, i. 13.

Unguiculate petal, ii. 250,

Unicellular organisms, green,
towards light, i. 382.

Unisexual flowers, ii. 291.

Unona, scent, ii. 202.

Upas-tree. See Antiaris towicaria,

behaviour

Upsala, floral clock, ii. 215.

Urania, caudex, i. 714.

Urea, absorption of, i. 104.

Uredinex, dispersal of spores, ii. 812,

— habit and characteristics, ii. 685.

Urocystis, spores, ii. 675.

Urocystis Viole, ii. 676.

Uromyces Alchemille, effect on Alchemilla
vulgaris, ii. 524.

Uromyces Phyteumatum,effecton Phyteuma
orbiculare, ii. 524.

Uromyces Pisi, and Euphorbia Cyparissias,

ii. 525.

‘ibomiyoes Primulzintegrifoli#, and Primula
Clusiana, &c., ii, 525.

Urophora cardi pud-galls on Cirsium
arvense, ii. 543.

Urpflanze, Goethe’s, i. 12.

Urtica, amount of pollen, ii. 151.

— bast-cells, i. 725.

— cotyledon stinging hairs, i. 623.

— ejection of pollen, ii. 94, 136.

— force of root-pressure in, i. 273.

— pollen-grain, ii. 102.

— pollination, ii. 133.

— species causing tetanus, i. 442.

Urticaces, ii. 719.

— andreecium, ii. 750.

— distribution of sexes, ii. 297.

Urtica dioica, and gall of Cecidomyia urticz,

ii. 534.

— — distribution of sexes, ii. 300.

— — stinging hair, i. 493.

Urtica urens, moncecious, ii. 297.

—— persistent cotyledons, i. 622.

—— protogynous, ii. 313.

— — stinging, i. 441.

Usuea barbata. Pl. XV.

— — Froticose Lichen, ii. 694.

Ustilagines, dispersal of spores, ii. 812.

Ustilago carbo. See U. segetum.

Ustilago longissima, hosts, ii. 675.

Ustilago Maydis, ii. 675.

Ustilago segetum, life-history, ii. 675.

Ustilago violacea, on Caryophyllacez, ii. 675.

Utricle, of Genlisea, i. 124.

— primordial, i. 25.

Utricularia, autogamy, ii. 356.

— dispersal of offshoots, ii. 807.

— embryo, i. 596.

— floating habit, i. 668.

| — leaves and bladders, i. 120.
| — pollen deposition, ii. 280.

— pollen dispersion, ii. 105.

| — protective isolation by water, ii. 234.

Utricularia Grafiana, i. 120.

Utricularia minor, i. 120.

Utricularia neglecta, traps, absorption cells,
i, 121,

Utricularia nelumbifolia, commensal with
Tillandsia, runners of, i. 123. %

Utriculariz, carnivorous plants, with trap-
bladders, i. 120.

— some nop-aquatic, i. 123.

Uvularia, autogamy, ii. 332.

— grandiflora, nectaries, ii. 177.

Vv.

Vacciniaces, ii. 770.

Vaccinium, hybrids, ii. 585.

— pollen tetrads, ii. 97.

— protection of pollen, ii. 107, 118.

— sticky stigmas, ii. 282.

Vaccinium Mpyrtillus, allurement of insects,
ii. 206.

— — dehiscence of pollen-sacs, ii. 92.

—— grooving of stem, i. 96.

——— mycorhiza, i. 251.

— —nectaries, ii. 175.

-— protogynous, ii. 310.

Vv: Oxy eae
sacs, ii. 92.

— — duration of flowering, ii, 214.

— — force of runners, i, 516.

—— stamen, ii. 91.

of polien-

Vaccinium Wiginosum, and Exobasidium
Vaccinii, ii, 526,
—-— autumnal tints, i. 490,
— — nectaries, ii. 175.
—-— Stamen, ii. 91.
Vaccinium Vitis-Idea, and animals, i, 432.
——— and Exobasidium Vaccinii, ii. 526.
——— and Melampsora Goeppertiana, ii.525.
——-— pollen-sprinkling, ii, 224,
—— —— shade and growth, ii. 506.
——— water-collecting and -absorbing or-
gangs, i. 231,
Vacuole, central, i. 41.
— systole and diastole, i. 30,
Vacuoles, pulsating, i. 31.
Vagina, of leaf, i. 595,
Valerian, Wild. See Valeriana officinalis,
Valeriana, imperfect flowers, ii. 294.
— leaf size and vertical height, i. 287,
— massing of flowers, ii. 186.
— scent, ii. 202, 488.
Valeriana dioica, imperfect flowers, ii. 295.
— — protogyny, ii. 312.
Valeriana globularizfolia, nectary, ii. 178.
Valeriana montana, anthocyanin, i. 520.
—— &c., distribution of sexes, ii. 298.
— — nectary, ii. 178.
Valeriana officinalis, cross-fertilization, ii, 307.
— — flower, ii. 178, 289.
— — fruit, ii. 432.
Valeriana Phu, elevation and coloration,
ii. 511.
Valeriana polygama, protogynous, ii. 312.
Valeriana saxatilis, scent, ii. 202.
Valeriana simplicifolia, elevation and col-
oration, ii. 511,
— — imperfect flowers, ii. 295.
Valeriana tripteris, anthocyanin, i. 520,
—— plumed fruits, ii. 857.
— — protogynous, ii. 312.
Valeriana tuberosa, store roots, i. 760,
Valerianacez, ii. 765.
— dichogamy in, ii. 312.
Valerianella Auricula, autogamy, ii. 351.
Valerianella carinata, autogamy, ii. 351.
— — doubling through gall-mite, ii. 549.
—— mite-galls, ii. 523.
Valerianella dentata, protogynous, ii. 310.
Valerianic acid, ii. 202.
Valerian scent, ii. 202.
Vallisneria, dicecious, ii. 299.
— flower-stalk, i. 53.
— pollen dispersion, ii. 105.
— venation, i. 636.
Vallisneria alternifolia, pollination, ii. 133,
Vallisneria spiralis, i. 667.
——and heat, i. ‘554.
—— flowers and pollination, ii. 132.
Valoniacex, thallus characteristics, ii. 646.
Valonias, colonies, i. 585.
Valvate dehiscence of pollen-sacs, ii. 93.
Vanda coerulea, duration of flowering, ii. 214,
Vanda teres, seed-dispersal, ii. 862.
—— seeds and hygroscopic hairs, ii. 859.
Vanessa Urtice, larve on nettles, i. 442.
Vanilla, scent, ii. 200.
Vanilla Orchid, ii. 738.
Variation, effect of habitat on, i. 394.
— possible factors in, ii. 593.
— structural, i. 8.
Variegation, causes of, i. 285.
Varnish excreting cells, distinctive features,
i, 237.
— protective coating, i. 353.
Varnish-like covering of epidermis, composi- |
tion, restrictive of transpiration, i. 312.
Vascular bundle, strengthening of, i. 725.
Vascular bundles, in leaf and stem, i. 649.
Vascular bundle-sheath, i. 469.
Vascular Cryptogams, alternation of genera-
tions, i. 709.
—— common characteristic, ii. 67.
— — Paleozoic remains, ii. 612.
— — sexual reproductive organs, ii. 62.
— — two generations distinct, ii. 474.
Vascular tissue and transpiration, i. 347, 362.
Vaucheria, Pl. I., ii. 57.

INDEX.

Vaucheria, chlorophyll granules, i. 373.
— cilia of, i. 29.
— colonies, i. 585.
— conditions favourable to development of
sexual organs, ii. 644,
— germination, i. 575.
— Klebs’ experiments, ii. 482.
— sporangium and spore, ii. 17.
Vaucheria clavata, as mud collector, i. 267.
— — motion of swarm-spore, i. 24,
-— ae and behaviour towards light,
i, 383,
— — zoospore-formation, ii. 645.
Vaucheria sessilis, fertilization, ii. 53.
Vaucheriacez, ii. 643.
Vega expedition, temperature observations,
i. 547.
Vegetable and animal bodies, analogies, i. 591.
— kingdom, divisions, ii. 617.
— mould, conditions of formation, i. 263,
Vegetable Sheep. See Haastia.
Vegetation, at mouths of drains, i. 105.
— characteristics on sea-shore, i. 390.
— coal period, i. 636.
— lines of, ii. 881.
— marine, vertical zone, i. 387.
— mountain limits, i. 527.
— of heaths and moors, indigestibility, i. 432.
Vegetative cell, of pollen-grain, ii. 420.
— propagation, ii. 790.
— — lengths of runners, ii. 802.
— — various causes, ii. 459.
Vella spinosa, spines, i. 444, 449.
Velum, of Isoétes, ii. 716.
— partiale, of Agaricines, ii. 689.
— universale, of Agaricines, ii. 689.
Velvety, texture, i. 320.
Venation, importance in Palzo-botany, i. 635.
— specific constancy, i. 635.
— of leaf, terminology, i. 629 et seq.
— of leaves, i. 631.
Venetian lagoons, tation, ii. 104.
Ventilation-canals, functions of, i. 63.
Ventral canal-cell, in Gymnosperms, ii. 419.
Ventral suture, of follicle, &c., ii. 430.
Venus’s Fly-trap. See Dionewa muscipula.
— Looking-glass. See Specularia speculum.
Veratrum, hermaphrodite and staminate
flowers, ii. 297.
Veratrum album, grooving of leaf, i. 96,
— — odourless, i. 431.
Verbascum, edible staminal hairs, ii. 170.
— hairs and animals, i. 442.
— hybrid flower colour, ii. 567,
— hybrids, ii. 585.
— leaves and light, i. 410.
— sterility of hybrids, ii. 571.
Verbascum <Austriacum, and bud-galls of
Cecidomyia Verbasci, ii. 544.
—— colour-contrast of flower, ii. 189.
Verbascum Blattaria, nectaries, ii. 177.
—— corolla and autogamy, ii. 367.
Verbascum Lychnitis, and bud-galls of Ceci-
domyia Verbasci, ii. 544.
Verbascum nigrum, and bud-galls of Ceci-
domyia Verbasci, ii. 544,
—— colour-contrast of flower, ii. 189.
Verbascum olympicum, hairs, i. 324.
Verbascum phlomoides, i. 97.
— — method of water-conduction, i. 96.
— — stomatal protective hairs, i. 292.
Verbascum pheenicum, nectaries, ii. 177.
Verbascum pulverulentum, deciduous pro-
tective branched hairs, i. 354.
Verbascum thapsiforme, hairs, i. 322.
Vert m Th y, ii. 350.
—— function of woolly hairs, i. 227.
—— stomatal protective hairs, i. 292.
—— tea, i. 443,
Verbascum verulentum, hairs, i. 324.
Verbena officinalis, honey protection, ii. 241.
Verbenacee, ii. 771.
Vernation, crumpled, i. 349.
— in relation to transpiration, i. 348.
— of pinnate leaves, i. 350.
— plaited, i. 349.
Veronica, opening of flower, ii. 212.

981

Veronica, protogynous, ii. 311.

— seed dispersed by rain, ii. 846.

— stamens as insect platform, ii. 225,

Veronica alpina, weather and autogamy, ii.
391.

Veronica Anagallis, extremes of growth, ii.
500.

—— leaves, aérial and submerged, ii. 501.

Veronica Beccabunga, habit and tempera-
ture, ii. 503.

Veronica bellidioides, weather and autoga-
my, ii. 391.

Veronica chameedrys and galls of Cecidomyia

Veronice, ii. 547.

— — elevation of petioles, i. 419.

— — inflorescence, ii. 226.

—— insects and pollen, ii. 245.

— — weather and autogamy, ii. 391.

Veronica hederifolia, origin of flower-stalk,
i. 737.

Veronica maritima, geitonogamy, ii. 326.

Veronica officinalis, elevation of petioles, i.

— — gall-mites and doubling of flowers, ii. 553,
—— honey protection, ii. 241.
Veronica pollita, light and growth, ii. 508.
Veronica preecox, anthocyanin, i. 512.
Veronica saxatilis, gall-mites and flower
metamorphosis, ii. 548.
Veronica scutellata, weaving habit, i. 674.
Veronica spicata, geitonogamy, ii. 326.
Veronica spuria, geitonogamy, ii. 326.
Verrucaria calciseda, heat resistance, i. 554.
Verrucaria purpurascens, heat resistance, i.
554.

Versatile anther, ii. 90.

— — of Grasses, ii. 141.

Verticillates, general characteristics, ii. 646.
Verticordia oculata, seed-dispersal, ii. 855.
Vervain. See Verbena officinalis.

Vessels, absence in seedling of Cuscuta, i. 172.
— in young Orobanche, i. 184.

— laticiferous, i. 470.

— nature of, i. 46,

— size, i. 362.

— spiral, i. 471.

— various, i. 469.

Vetch, Bitter. See Orobus vernus.

Vetches, S. Europe, phyllodes, i. 335.
Viburnum lantana, behaviour of stamens, i.

— — deciduous stellate hairs, i. 354.

— — geitonogamy, ii. 326.

—— scent, ii. 200.

— — texture of mite-gall, ii. 533.

— — unfolding leaves, i. 349.

Viburnum Lentago, i. 488.

Viburnum Opulus, geitonogamy, ii. 326.

— — peripheral flowers, ii. 187.

—— scent, ii. 200.

——water-absorption, direct from atmo-
sphere, i. 238,

Vicia, how protected, i. 451.

— keel movements and pcllen-brush, ii. 252,

— seeds and heat, i. 555.

— tendrils, i. 693.

Vicia amphicarpa, cleistogamy, ii. 393.

Vicia Cracca, elevation and coloration, ii. 511.

Vicia dumetorum, seed protection, ii. 446.

Vicia Faba, colour-contrast of flowers, ii. 189.

Vicia Melanops, ii. 190.

Vicia picta, ii. 190.

Vicia pisiformis, seed protection, ii. 446.

Vicia sepium, elevation and coloration, ii. 511.

Vicia sylvatica, seed protection, ii. 446.

Victoria regia, anthocyanin, i. 521.

—— colour contrast of flower, ii. 190.

——jinthe River Amazon. Pl. XI.

—— leaf and transpiration, i. 288,

—— position of stomata on leaves, i. 280,

—— prickles, i. 433.

—— protective isolation by water, ii. 234.

—— size of flowers, ii. 185,

— — venation, i. 636.

Vienna, time of flowering, i. 518.

Villarsia, allurement by petals, ii. 171.

— leaf-rosettes, i. 412.

982

Villarsia nymphoides, anthocyanin, i. 521.
~—— leaf and transpiration, i. 288.

Vinca, zestivation, ii. 210,

— stolons, i. 663.

Vinca herbacea, flower, ii. 240.

— — honey protection, ii. 241.

—— stigma, ii. 240.

—— style, ii. 240.

Vinca major, and Puccinia Viner, ii. 525,
— — vitality of spermatoplasm, ii. 96.
Vinca minor, and Puccinia Vince, ii. 525.
— — flower colour and surroundings, ii. 194.

Vine. See Vitis.

Vine-mildew, False. See Peronospora viti-
cola.

——True. See Erysiphe Tuckeri.

Vine-pruuing, varies with locality, ii. 37.

Viola, capsule, ii. 431.

— flower, day and night positions, i. 531.

— hybrids, ii. 584.

— nectary, ii. 178.

— pollen-sprinkling, ii. 276.

— propagation of bybrids, ii. 556.

— protection of pollen from wet, ii. 110.

— rhizome and light, i. 484.

— venation, i. 633.

Viola arvensis, autogamy, ii. 387.

— — cleistogamy, ii. 394,

— — light and growth, ii. 508.

Viola calcarata, colour and locality, ii. 194.

Viola collina, cleistogamy, ii. 393.

Viola cucullata, elevation and coloration,
ii. 511.

Viola elatior, seed-dispersal, ii. 835.

Viola mirabilis, cleistogamy, ii. 393.

—— scent, ii. 201.

Viola odorata, flower and parts, ii. 279.

—— ovary, ii. 73.

—— scent, ii. 200.

— — stamens, ii. 87.

Viola polychroma, scent, ii. 201, 204.

Viola sepincola, cleistogamous and other
flowers, ii. 395.

Viola tricolor, autogamous hybrids, ii. 579.

—— autogamy, ii. 387.

—— colour-contrast in flower, ii. 190.

—— periodically pendulous flowers, i. 530.

—— pollen-grains, ii. 97, 98,

——scentless, ii. 204,

—— seed and embryo, ii. 425.

— — stipules, i. 637.

— — vitality of spermatoplasm, ii. 96.

Violet. See Viola.

Violet-st See Tr

11a,

Tolithus,

Violet Willow. See Salix daphnoides.

Viper’s Bugloss, See Echium.

Virginian Creeper. See Ampelopsis heder-
acea,

Viridiflora, ii. 758.

Viscaces, ii. 754.

Viscin, of pollen-grains, ii. 101.

Viscum, green cotyledons, i. 622.

— watery pulp of berries, i. 329.

Viscum album, attachment to host, sinkers,
i. 209. -

— — berry, i. 427.

——best known and widely distributed4
member of Loranthacez, i. 204,

— — branching, i. 749.

—— cuticle of leaf, i. 310.

—-—effect of removing parent plant on
adventitious buds, i. 210.

— — evergreen, i. 212,

—— pari passu growth of root and stem, i.
209.

—— pollen grains, ii. 99.

— — radicle, mode of attachment, i. 207.

— — stamen, ii. 87.

Viscum moniliforme, parasitic on V. orien-
tale, India, i. 213.

Viscum Oxycedri, i. 210.

Vital force, i. 52, 509.

—— and respiration, i. 497.

Vitality, of protoplasm, i. 51.

— of seeds, i. 51.

‘Vitex Agnus-castus, reserve-buds, ii, 32.

Vitis, i, 488,

INDEX.

Vitis, anthocyanin, i. 484.

— hybridization in, ii. 570.

— mite-galls, ii. 529.

— opening of flower, ii. 211.

— used for experimental determination of
root-pressure, i. 272.

Vitis cordata, distribution of sexes, ii. 300. ~

Vitis inconstans, tendrils, i. 699.

Vitis inserta, tendrils, i. 699.

Vitis macrocirrha, distribution of sexes, ii.

et

Vitis Royleana, adhesive discs, i. 699.

Water, periodic surrender and resistance to
heat, i. 555.

— proportion to bulk of plant, i. 216.

— rapidly-flowing, effect on plants, ii. 502.

— removal, i. 216.

— réle in turgidity, i. 511.

— stilland running, relating to nutrition, i.78.

— supply of, i. 82.

Water-absorbing apparatus, localization of,
in Populus tremula, &c., i. 238.

——— special, structures of foliage-leaves,
i. 227, 231, 233.

Vitis sylvestris, distribution of sexes, ii, 298.“Water-absorption, by aérial organs in moist

Vitis vinifera, bark, i. 720.

—— berry, ii. 427.

— — flower-opening constant, i. 559.

—— imperfect flowers, ii. 294,

—— scent, ii. 207, 209.

— — separation-layers, i. 360.

Vittaria, protection of sporangia, ii. 13.

Viviparous, botanical use of term, ii. 454.

Véchting, grafting experiments with Helian-
thus, ii. 572.

Vochysia, seed, ii. 423.

Volva, of Agaricines, ii. 689.

Volvocines, movement of, i. 37.

Volvox aureus, life-history, i. 635.

Volvox globator, structure, ii. 634.

—— known to Leeuwenhoeck, i. 37,

Vordere Kaiser, limestone chain, character-
istic vegetation, ii. 495.

|

W.

Waldsteinia geoides, autogamy, ii. 381.

—— winter protection, i. 550.

Wall, of wood-cells and vessels, nature, i. 277.

Wall-Pellitory. See Parietaria.

Wall-rue Spl See Aspi
muraria,

Walls, partition, probable significance in
conducting cells, i. 482.

Warming, classification of Thallophytes, ii.
606.

Wasp of Chalcidid, and Ficus, ii. 159.

Wasps, and brown flowers, ii. 197.

Water, absorption and exhalation, general
considerations, i. 226.

— absorption by aérial organs, i. 156.

— agent in seed-dispersal, ii. 844,

— agent in weathering, i. 83,

—alternating absorption and expulsion by
epidermal cells, i. 370.

—and “burning” of plants, i. 554,

— and carbonic acid, joint effect, ii. 499.

— and freezing of plants, i. 545.

— and growth, i. 510.

— atmospheric, gases in, i. 368.

— centrifugal transmission of, i. 94.

— centripetal transmission of, i. 94.

— circulation of, i. 83.

—colour of, i. 388.

— conditions of plant life in, i. 665.

— conduction, i. 366.

—conduction and absorption by hairs of
Stellaria media, i. 228.

— conveyance, i. 513,

— depth, and chlorophyll, i. 387.

— excretion in freezing of plants and salt
solutions, i. 541.

— extrusion of, through root-pressure, i. 271.

— ferment action, i. 465.

— formation during putrefaction, i. 263.

— importance to plant as dynamic agent,
i, 216,

—loss of constituents through plants not
directly observable, i. 258,

— minimum quantity in seeds, importance
of, regulation of supply, &c., i. 217.

—obtained from tree-bark by epiphytic
orchids, i. 222.

— of imbibition, proportion to dry subst:

Ruta-

ort.

habitats, probable explanation, i. 241.

—— by aérial roots, i. 225.

— — by leaves not protected against wetting,
experimental evidence, i. 230.

—— by seed, ii. 425.

— — by special leaf-teeth in tall herbs, i. 238.

—-— in hydrophytes, lithophytes, epiphytes,
and land-plants, i. 217.

— —in Lichens, Mosses, Liverworts, i. 218.

Water-birds disperse fruits, ii. 867.

— — list of plants dispersed by, ii. 868.

Water-chestnut. See Trapa.

Water-crowfoots, See Ranunculus.

Water-hemlock. See Cicuta virosa.

Watering, object and result of, i. 225.

Water-lilies. See also Nymphea, Nuphar,
Victoria.

— — epiphyllous buds, ii. 43.

— — habit, i. 666.

—— pollen-grains, ii. 99.

— — shadows of leaves, cause of, i. 289.

— — stamens and perianth-leaves, i. 646.

— — venation, i. 632.

Water-lily, amphibious adaptation, i. 425.

Water Milfoil. See Myriophyllum.

Water-net. See Hydrodictyon.

Water Parsnip. See Sium.

Water-plantain. See Alisma.

Water plants, absorption of carbonic acid, i.
61.

—— and land plants, nutrition compared, i.

—— and offshoots, ii. 456.

—— and temperature, ii. 503.

— — food-absorption, i. 75.

—— groups, i. 666.

—— importance as mud-collectors, i. 266.

— — lime incrustation, i. 61.

— — pollination, ii. 130.

—-—rarely attacked by parasitic Fungi, i.
169.

— — seed-bearing, mode of attachment, i. 77.

— — whence obtain ammonia, i. 65.

‘Water-pore and honey secretion, ii. 172.

Water-pores, i. 366.

Water-receptacles, i. 239.

—— organic remains, &c., found in liquid of,
i. 242.

Water-retaining substances, i. 329.

Water-soldier. See Stratiotes aloides.

Water-star. See Callitriche.

Water-starwort. See Callitriche.

Water vapour, condensation by Orchid roots,
i. 223.

—— exbalation of, practically restricted to
spongy parenchyma, i. 285.

—— maint of free for, i. 290,

Water-violet. See Hottonia.

Waterwort. See Elatine.

Wax, coating of, as protection of stomata

from being wetted, examples, i. 291.

— in grafting, i. 214.

— in Langsdorfiias, i. 188.

— protective coating on leaves, i. 292.

Wax-like coating on leaves, use of, i. 226.

—-—excretions, protection from excessive
evaporation,experimental proof, i. 312.

Waxy coatings of flowering axes, ii. 237.

Weapons, of plants, i. 432, 439, 449.

Weather and heterogamy, ii. 390,

— seed protection against, ii. 447.

i. 217.
— on plants, a protection, i. 432.

— path and mode of ascent, ii. 277.

Weaving stem, mechanical tissue, i. 732.
— undershrubs, i. 673.
Webera nutans, habitat, i. 109.

,

Wedge-roots, of Loranthus Europsus, mode
of growth, &e., i. 211.

Wedge-shaped apical-cell, i. 578.

Weeping, of plants, explanation, i. 271.

— in Aroid roots, i. 366.

— of Vines, when most vigorous, i. 270.

Wellingtonia. See Sequoia gigantea.

Welwitschia mirabilis, in habitat, ii. 727.

— — geographical distribution, ii. 726.

West-Indian Sour-sop. See Anona muricata.

Wettstein, and anatomical characteristics of
hybrids, ii. 565.

Wheat, seeds and heat, i. 555.

— starch, i. 459.

White, visibility to insects, ii. 197.

White Hellebore. See Veratrum.

White Mustard. See Sinapis alba.

White-thorn. See Crategus Oxyacantha,

Whitlow-grass. See Draba.

Whorl, of perianth-leaves, i. 641.

Whorls, sorts of, i. 397.

Whortleberry, Common.
Myrtillus.

Wichura, hybridization of Willows, ii. 560.

Wigandia urens, stinging hairs, i. 441,

Wightia, clinging roots, i. 702, 754.

Wild Cress. See dithionema.

Wild Pear, spines, i. 433.

Will-o’-the-Wisp, and luminous mycelium, i.
503.

Willow. See Salix.

Willow, Gray. See Salix incana.

Willow-herb. See Epilobium.

Willows, Alpine, Tyrol, i. 524.

Wind, agent in spore-dispersal, ii. 812.

— and fruit boring, i. 618.

— and position of leaves, i. 427.

— and seed dispersal, ii. 447.

— and stunted growth, i. 524.

Wind Bent-grass. See Apera spicaventi.

Wind-fertilized plants, characteristics, ii. 133.

Wind-pollination,adaptation of stigma, ii. 151.

Wind-witches, ii. 850.

Wine-cask Fungus, i. 508.

Wine-flower scent, ii. 202.

Wings of Papilionaceous flower, ii, 228.

Winter-buds, of Aldrovandia, i. 152.

Winter Cherry. See Physalis Alkekengi.

Winter-green. See Pyrola.

Winter resting of plants, i. 562.

Witches’ Brooms and Exoascus, ii. 676.

— — caused by gall-mites, ii. 548.

—— cause of, ii. 518.

——on Abies pectinata, ii. 526.

— — on various trees, ii. 527.

Wolffia, rootless, ii. 745.

Wood, ascent of sap through, i. 274.

— changes due to attack of hyphe, i. 167.

— longitudinal splitting in twiners and
climbers, i. 733.

— “luminous”, i. 502.

— of host, effect of Langsdorffia on, i. 187.

Wood-ash, effect on Mosses, Grasses, Poly-
gonaceous and Cruciferous plants, i. 74.

Woodbine, Alpine. See Lonicera Alpigena.

Wooden Pear. See Xylomelum pyriforme.

Wood-parenchyma, i. 469.

Woodruff. See Asperula odorata.

Wood-sorrel. See Oxalis.

Wood-vessels and cell, views regarding func-
tion, i. 276.

Woody fibres, nature of, i. 726.

Woody stem, characteristics, i. 715.

Woolly hairs, nature of, i. 320.

See Vaccinium

INDEX,

Wormwood, Common. See Artemisia Ab-
synthium.

Wormwoods, hairy covering in summer, i. 319,

Woundwort. See Stachys.

Wracks. See Fucacee,

Wrangelia, luminosity, i. 388,

X.

Xanthidium aculeatum, ii. 492, 655.

Xanthidium octocorne, ii. 492.

Xanthium, protogynous, ii. 313.

Xanthium spinosum, and cattle, i. 451.

— — fruits and dissemination, i. 615.

— — hooked capitulum, ii. 873.

Xanthophyll, from chlorophyll, i. 372.

Xanthorrhea, caudex, i. 714.

— mode of growth, i. 659.

Xanthorrhea hastilis,‘height, Pl. XVL., ii. 731.

Xenogamy, in hybrids, ii. 583.

— nature of, ii. 317.

Xeranthemum, hairy covering in summer, i.
319.

Xeranthemum annuum, coloured bracts, ii.
183.

Xylaria Hypoxylon, ii. 679.

— — stroma, ii. 681.

Xylaria polymorpha, stroma, ii. 681.

Xylocopa violacea and Spartium scoparium,
ii, 267.

Xylomelum pyriforme, fruit, ii. 430, 431, 751.

—— protecting pericarp, ii. 449,

Ni.

Yakutsk, winter cold, i. 544,

Yeast fermentation, nature of, ii. 519.

— ferment of, i. 465.

Yeasts. See also Saccharomyces.

— fermentative, i. 505.

Yellow granules of autumn leaves, i. 485.

Yellow-rattle. See Rhinanthus Crista-galli.

Yellow Vetchling. See Lathyrus Aphaca.

Yew. See Taxus buccata.

Vilang perfume of Zaluzianskia, ii. 242.

“York and Lancaster” Rose, ii. 568.

Yucca, acicular leaves, i. 434,

— and insect visits, ii, 222.

— and night visitors, ii. 196.

— caudex, i. 714.

— cotyledon in germination, i. 606.

— fertilization by Moths and advantage to
the insects, i. 255.

— infertility in Europe, ii. 403.

— mode of growth, i. 660.

— phyllotaxis, i. 402.

— pollination by Pronuba y
245.

Yucca aloefolia, fertilization, ii. 158, 159.

— — fertilization, geographical distribution,

ii. 159.

Yucca angustifolia, pollen-grains, ii. 97.

Yucca gloriosa, i. 659; ii. 732.

Yucca Treculeana, fertilization and geo-
graphical distribution, ii. 159.

Yucca Whipplei, non-fruiting, ii. 158.

a, ii. 157,

983

Z.

Zaluzianskia lychnidea,
scent, ii, 202, 241.

Zamia, cotyledon in germination, i. 606.

— spiny leaves, i. 438.

Zannichellia, monoecious, ii. 297,

— pollen and pollination, ii. 105.

— root origin, i. 766.

Zanthoxylon, reserve-buds, ii. 32.

Zea Mays, and Ustilago Maydis, ii, 524, 675.

—— moneecious, ii, 297.

— — protogynous, ii. 313.

— — stilt-roots, mechanical tissue, i. 762.

—— vitality of spermatoplasm, ii. 96.

——&c., reared in artificial culture solu-

tion, i. 100.

Zero of growth, i. 561.

Zigzag stem, i. 658.

Zingiber, venation, i. 634.

Zingiberacez, stamens, ii. 736.

Zinnia hybrida, colour-contrast in capitulum,
ii. 191.

Zonotrichia, in waterfalls, i. 79.

— movement of, i. 39.

Zoogleea, bacterial condition, ii. 622.

— of Micrococcus prodigiosus, ii. 624.

Zoophytes, appropriateness of name, ii. 469.

Zoospore, eye-spot, ii. 629.

— of Botrydium, ii. 642.

— of Vaucheria, ii. 644.

Zoospore formation, in Hydrodictyon, ii. 641.

Zoosporesx, ii. 606.

Zoospores, ii. 17.

— behaviour towards light, i. 382.

— of Chlorophycew, ii. 628.

Zostera, i. 77.

— habit, &., i. 666.

— pollen and pollination, ii. 104, 105.

Zostera marina, ii. 738,

Zygena, and honey scent, ii. 207.

Zygnema, cell-division, i. 577, 581.

— characteristics, ii. 658.

— chlorophyll bodies, cf. Pl. I., i. 373.

— conjugation, ii. 658.

Zygnema pectinatum, Pl. I.

Zygnemacee, ii. 658.

— chromatophores, ii. 654,

— conjugation, ii. 55.

Zygnemesx, filaments, i. 586.

Zygnemoide, characteristics, ii. 654.

Zygogonium, nature of, ii. 54.

Zygomorphic symmetry, ii. 229.

Zygomycetes, characteristics, ii. 673.

Zygosporeinvestment, in Mortierellez, ii. 674

— of Mucor, ii. 673.

— of Mucorini, ii. 481, 484.

Zygote, nature of, ii. 54.

— of Botrydium, ii. 642.

— of Chlorochytrium, ii. 637.

— of Chlorophycee, ii. 628.

— of Conjugate, ii. 654.

— of Desmids, ii. 654.

— of Hydrodictyon, ii. 641.

— of Pediastrum, ii. 639.

— of Phyllobium, i.-638.

— of Spirogyra, ii. 658.

— of Volvox globator, ii. 635.

Zygotes of Ulothrix zonata, ii. 648.

Zygozoospore, formation, ii. 632,

Zygozoospores, of Chlorochytrium, ii. 637,

— of Phyllobium, ii. 638.

pollination and

— of Stephanosphera, &c., ii, 632.

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