John Swett

SCIENCE PRIMERS, edited by

PROFESSORS HUXLEY, RoSGOE, and
BALFOUR STEWART.

VIII
BOTANY.

BOTANY.

BY

J. D. HOOKER, C.B., P.R.S.

WITH ILLUSTRATIONS.

NEW YORK :
D. APPLETON AND COMPANY,

549 AND 551 BROADWAY.

i877.

Q.K4

PREFACE.

THE object of this Primer is to supply an elementary
knowledge of the principal facts of plant-life, together
with the means of training beginners in the way to
observe plants methodically and accurately; and in
the way to apply the knowledge thus obtained to
the methodical study of Botany.

It is hoped that by its means the teacher may
convey a sound elementary knowledge of the number,
nature, relative positions and uses of the principal
organs of plants, of the order and way in which they
grow, and in which plants multiply, and of those
resemblances which exist amongst them, by a com-
parison of which their true relationships are known
and themselves classified.

In using this Primer the plants indicated are, when-
ever possible, to be put into each pupil's hand.
Hence, to facilitate its use, I have placed at the end
an Index of the plants referred to in it. These may
be procured in the country, or from any intelligent
nurseryman. Many of them should be grown in every
school-garden, and arranged in it systematically, so
that the teacher may have the same means of dis-
playing to his pupils the principles of classification
that the great founder of the natural classification of
plants, Bernard de Jussieu, had after he had thus

vi PREFACE.

arranged the Garden of the Palace of Trianon after
its establishment by Louis XV.

The teacher should further have a copious supply
of dried flowers, and other parts of these plants so
preserved as that the pupil can, after -moistening
them in warm water, separate their organs. Much
may thus be learnt when fresh plants cannot be
obtained, and a rehearsal of the summer's lessons
upon such dried specimens is a most improving
exercise. He should also have a supply of preserved
fruits, seeds, sections of stems, and of mounted pre-
parations of the tissues and minute parts of plants
adapted for exhibition under the microscope.

Each pupil should have a pocket-lens magnifying
three or four times, a sharp pen-knife, and a pair of
forceps ; and he should be taught to preserve between
sheets of paper the specimens he has examined, with
a descriptive ticket attached ; and also be exercised
in the habitual use of the schedules described at
pp. 112, 113.

In using the Primer the pupil should be taught
first, the contents of sections I. and II. ; after which
he may either take the other sections in order, or go
on to section VI., taking sections III. to V. after-
wards. Sections XIX. and XXV. are too difficult for
beginners.

After mastering its contents the pupil may proceed
to the use of Professor Oliver's " Lessons in Elemen-
tary Botany," which goes over the same ground in
more detail.

CONTENTS.

SECT. PAGE

I. — INTRODUCTORY i

II. —GENERAL CHARACTERS OF FLOWERING

PLANTS 8

III. — THE TISSUES OF PLANTS ic

IV. — THE GROWTH OF CELL-TISSUE, AND NATURE

OF THE CELL 13

V. — THE FOOD OF PLANTS 20

VI. — THE GROWING SEED 23

VII.— THE ROOT 28

VIII.— THE STEM 33

IX.— THE BUDS AND BRANCHES 38

X. — THE LEAVES 40

XI.— THE INFLORESCENCE 45

XII. — THE FLOWER 47

XIII.— THE CALYX 62

XIV.— THE COROLLA 63

XV.— THE DISK 66

XVI. — ^ESTIVATION 67

XVII.— THE STAMEN 68

XVIII.— THE PISTIL 72

XIX.— THE OVULE 74

XX. — FERTILIZATION 76

XXI.— THE FRUIT 80

XXII.— THE SEED 89

XXIII. — SURFACE COVERINGS AND APPENDAGES . . 93

XXIV. — GYMNOSPERMOUS PLANTS 95

XXV. — CLASSIFICATION . 97

XXVI. — PHYSIOLOGICAL EXPERIMENTS 102

XXVII. — A SCHOOL-GARDEN OF FLOWERING PLANTS 107
XXVIII — SCHEDULES FOR EXERCISES ON LEAVES

AND FLOWERS in

INDEX 114

LIST OF ILLUSTRATIONS.

PAGE

Fig. i. — Cellular tissue of rounded cells 10

„ 2. — Cellular tissue of rather long cells .... 10

„ 3. — Thick-walled cells from a leaf of Stone-pine . 1 1

,, 4. — Spiral-vessels with cellular tissue on each side . 12
„ 5. — Growing point of stem of Stonewort showing

formation of new cells by division .... 13

„ 6. — Starches 17

jj 7> 8, 9. — Crystals of oxalate of lime, as found in

cells 19

„ 10. — Pea "24

„ ii. — Germination of Mustard 25

„ 12. — Wheat germinating 26

„ 13. — Vertical section of tip of root-fibre of

Hyacinth 29

„ 14. — Root^hairs 30

„ 15. — Tubercles and root-fibres of Orchis .... 31

„ 16. — Creeping stems and roots of Couch-grass . . 32
„ 17. — Transverse section of vascular bundle from

stem of a Dicotyledon 35

,, 1 8. — Transverse section of stem of a Dicotyledon . 35

„ 19. — Transverse section of stem of a Monocotyledon 37

„ 20. — Leaf-buds and vertical section of ditto ... 38

„ 21. — Fragment of epidermis with a stomate ... 43

„ 22. — Vertical section of Buttercup flower .... 51

„ 23. — Vertical section of Bramble flower .... 52

„ 24. — Vertical section of Wall-flower 52

„ 25. — Stamens of Wall-flower 52

„ 26. — Vertical section of flower of Mallow. ... 53

„ 27. — Section of flower of Pea 54

„ 28. — Vertical section of flower of China Primrose . 54

„ 29. — Transverse section of ovary 54

„ 30. — Vertical section of Dead-nettle flower ... 55

„ 31. — Vertical section of Rose 56

„ 32. — Vertical section of Apple flower 56

„ 33. — Vertical section of head of Daisy 57

34. — Inner flower from head of Daisy 57

35. — Vertical section of Daphne flower .... 58

36: — Vertical section of Tulip flower 59

37. — Vertical section of Daffodil flower .... 59

38. — Male flower of Willow 60

39. — Female flower of Willow 60

40. — Spikelets of Wheat 6 1

41. — Dandelion fruit with pappus 63

LIST OF ILLUSTRATIONS.

PAGE

Fig. 42. — Thistle fruit with pappus 63

43. — Spotted orchis- flower 64

44. — Honey glands of Buttercup and Barberry . . 66
45. — Disks of Orange and Mignonette .... 67

46. — Estivations 68

47. — Stamens of Pea 69

48. — Stamens of Bilberry, Heath, Barberry, and

Mistletoe 70

49. — Transition from stamen to petal, and to sepal,

in double rose 70

50. — Pollen grains of Orange, and of Buttercup
upon the stigma with their tubes descending

to the ovule 71

51. — Pollen grains of Evening Primrose, and Cherry,

both emitting pollen tubes 71

52. — Axile ovules 73

53. — Parietal ovules 73

54. — Growth of ovule of Celandine 74

55. — Longitudinal section of ovule of Heartsease . 75
56. — Corolla of long-styled and short-styled Prim-
rose 77

57. — Section of flower of Orchis, showing a bee
standing upon the lip with its head touching
the sticky gland to which the pollen masses
are attached ; bee's head with the pollen
masses as removed ; the same with the pollen
masses after they have moved forwards . . 79

58. — Aggregate fruit of Mulberry 82

59. — Fruit of Pig cut vertically; male and female

flowers 82

60. — Section of fruit of Nettle ; section of seed of

the same, showing the embryo 83

61. — Fruit of Pea splitting into two valves ... 84
62. — Fruit of Buttercup, cut open showing the seed ;
seed of the same cut open showing the small
embryo within the small albumen .... 84
63. — Fruit of Bramble with stamens and calyx be-
neath it 85

64. — Fruit of Strawberry with calyx and bracts

beneath it 85

65. — Fruit of Mallow surrounded with the calyx . 86

66. — Fruit of Apple cut across 87

67. — Pod of Wallflower with one valve coming off . 88
68. — Experiment with bottle in basin 103

SCIENCE PRIMERS.

BOTANY.

I.— INTRODUCTORY.

THE study of Botany is best commenced with the
careful observation of the different parts of living
plants, their positions and arrangement in reference
to one another, the order in which they make their
appearance, and their uses to the plant itself. It is
hence often called a science of observation, in con-
trast to Chemistry and other subjects of which the
study must necessarily commence with experiment.
But Botany is also an experimental science ; only the
experiments by which we investigate the growth of
plants, their modes of living and multiplying, and
their relations to the air and soil, require much to have
been learnt first by observation alone. Such experi-
ments require also for the most part a previous know-
ledge of Chemistry and Physics; those, however,
described in this Primer will need no more knowledge
of these subjects than is to be found in the Primers
devoted to them.

Plants are living things ; they form the Vege-
table Kingdom as animals form the Animal King-
dom. Like animals, plants pass through the stages

2 V J I 'SCIENCE PRIMERS. [i.

of inrancy,;ihatur;fy, arid death ; they also feed, grow,
and multiply. Unlike the higher animals, during the
ordinary processes of growth (with the exception of
germination and flowering) they have no proper heat,
not being warmer than the air or water in which they
live.

Duration of Plant-life. — Some plants have
limited lives, flowering but once and dying soon after;
others have unlimited lives, throughout which they
flower periodically. Plants with limited lives are: i.
Annuals, which live but for one year or season, as
wheat, peas, &c. ; 2. Biennials which live for two
years, as the cabbage, turnip, foxglove, &c. ; and 3.
plants which grow for many years without flowering
(for example many palms), flower but once, and
then die. Those with unlimited lives are Perennials,
and may be either trees and shrubs which, like the
oak and hawthorn, have stems and branches increasing
in size from year to year ; or herbs like the primrose
and snowdrop, having underground root-like stems
which annually send up leaves or branches that die
off in the same year.

Distribution of Plants.— Plants are found on
nearly all parts of the surface of the globe, but no
two countries have all their plants alike. They are
found in the greatest luxuriance and variety in hot
and damp climates. They are not found in the
very coldest or very dryest regions, nor at very great
depths in lakes, or the ocean. As a rule, they
diminish in size, as well as in number of kinds in pro-
ceeding from the tropics to the frigid zones ; as regards
size there are exceptions, as the gum-trees of South
Australia and the wellingtonia of California, which

I.] BOTANY.

are amongst the most gigantic of known plants ; the
seaweeds of cold seas are also far more bulky than
those of tropical regions.

Besides the plants now growing upon the surface of
the earth, the remains of many others that are no
longer living anywhere, are found in rocks at various
depths beneath it. Of these, those that lived most
recently and are hence found in the more newly
formed rocks, are like existing plants ; those that
lived longer ago are less like existing ones, and are
sometimes very different looking indeed. In short,
the longer ago the plants lived the less like they were
to plants now living : but however different are the
plants that lived longest ago, they all seem to have
grown much in the same way, to have depended on
similar conditions of light, heat, and moisture, and to
have followed the same general course of life.

The Forms of Plants are infinitely varied.
As trees, shrubs, herbs, grasses, ferns, &c., they are
familiar to all ; but only a small proportion of the
Vegetable Kingdom consists of such plants. The
bright green covering of banks, tree-trunks, damp
walls, and cottage roofs, and the carpeting of forests
and wooded valleys, chiefly consist of mosses and moss-
like plants, of which several hundred kinds grow in
Britain alone. The ocean's surface sometimes swarms
with extremely minute plants, to such an extent as to
give the water a distinct colour ; and its shores within
and beyond the tide level are covered like gardens
with sea-plants of many forms and colours. As green
and purple slimes, plants also stain damp walls, and
the rocks and stones in the bottom of fresh-water
streams and along the seashore; as leathery or
2

4 SCIENCE PRIMERS. [i.

powdery crusts they cling to the hardest rocks and
stoniest soils of mountains and moorlands ; as moulds
they spoil articles of food, books, leather-work, woollen
and other fabrics ; as dry-rot, and under many other
forms, they utterly destroy trees, wooden houses and
ships ; as smut, rust, bunt, potato- and vine-blight,
they prey upon the living tubers, stems, leaves, and
fruits of the most valuable crops, and some even
invade the organs of living animals.

Things Necessary to the Life of Plants are
air, heat above the freezing point, light, water, and
earthy (inorganic) matter in some shape. The ex-
ceptions to this are few ; amongst them are the Red-
snow plant, a most minute vegetable, which 'tinges the
surface of melting snow with a rosy hue ; and fungi,
of which some grow or are cultivated in total dark-
ness. No plants, except these, continue to live in
health in the absence of light, as a few blind animals
can do (fishes and insects) which inhabit caves, as
well as many deep-sea animals, and those that live in
the interior of others.

The Division of Labour in Plants. — During
their life-time plants perform various kinds of work
which are essential, some to sustain them in life and
health, others to reproduce their kind. These kinds
of work being very different from one another are not
accomplished by any portion of the plant indiscrimi-
nately but are carried on by particular parts specially
fitted for the purpose (called organs).

In the case of flowering plants, for example, the
principal Organs are, i. The Root, by which the
plant is fixed to the ground, and absorbs /nourishment
from it; 2. The Stem, which supports the buds,

I.] BOTANY.

leaves, flowers, and fruit; 3. The Leaves, which are
usually thin and so placed as to receive as much
light as possible upon one surface ; 4. The assem-
blage of organs called the Flower; a part of this
grows into the Fruit, which contains the Seeds.

The purposes which organs are specially fitted to
serve are called their Functions. The most im-
portant of these in all plants are nourishment and
reproduction. Plants have no organs of locomotion,
or of the senses.

In Flowering Plants Nourishment is effected
by means of the root and leaves. Unlike animals,
such plants have no special stomach to receive the
food, no heart or blood-vessels to distribute it, and
no special organs to carry off what is not used as
nutriment.

The Food of plants is liquid and gaseous, never
solid. The root absorbs water, in which both gaseous
and mineral matters are dissolved ; and this fluid
ascends and enters the leaves, which also take in
carbonic acid gas from the air. By the action of
light on the water and carbonic acid in the leaves a
substance called Starch is formed, which is distri-
buted throughout the plant, supplying in great mea-
sure the material for adding to its parts.

The excess of water taken up by the root is ex-
haled by the leaves, and this tends to keep them cool.
From the starch produced in the leaves and nitro-
genous compounds taken up by the roots and dissolved
in the fluids which permeate the plant, albuminoids
are formed, which are very essential in producing
growth. These fluids further supply the materials
from which are manufactured by the plant various

6 SCIENCE PRIMERS. [i.

substances, such as resin, sugar, oil, wax, and colouring
matters,

The Reproduction of Plants takes place in
two ways. First, and principally, by seeds ; secondly
by buds that separate and grow into independent
plants. Seeds are produced by the interaction of
special organs of two kinds, and are inclosed in a
covering called the fruit. Buds that separate them-
selves and become new plants are formed on various
parts of plants, as where the leaf is attached to the
stem in the tiger-lily and the tubers or underground
branches in the potato plant.

Many plants may be artificially increased by divi-
sion ; that is, by cutting off a twig with a bud on it,
and sticking it into damp ground, when the twig will
send forth roots. Or the twig may be inserted into a
slit in the branch of a similar tree, with which it will
unite, and the bud thus nourished will grow, and pro-
duce leaves, flowers, and fruits.

The Tissues of Plants. — The substance of
plants is not, like a piece of stone, made up of
particles in which no definite form or structure is
visible, but is built up of minute bags called cells, and
of tubes called vessels (which also consist at first of
rows of cells), packed more or less closely together.

The Chemical Constituents of Plants. —
Plants, like animals, contain a far greater weight of
water than of anything else. Besides the elements
of water (oxygen and hydrogen), the tissues contain
carbon (which is the charcoal left after burning), and
some also contain nitrogen. Plants obtain the water
principally by their roots; the carbon by their leaves
.rom the carbonic acid gas absorbed from the air, and

I.] BOTANY.

the nitrogen in solution by the roots, from salts of
ammonia (or nitrates). Most plants contain moreover
small quantities of one or more mineral substances,
also absorbed in solution by the roots.

The green colour which prevails amongst plants
depends on the presence of a peculiar matter (Chloro-
phyll) within the cells, especially those near the surface
of the plant. This matter is coloured green only by
the action of light, consequently plants grown in quite
dark places are never green, nor are those parts of them
which are not exposed to the light (such as the roots).
The lustrous hue and glossy appearance of most leaves
is due to the fact of the coloured matter not being
superficial, but inclosed in cells whose sides are
usually as transparent as glass, and whose surface
reflects the light.

The Primary Divisions of Plants. — Plants
do not present a disorderly mass of living things,
having no degrees of relationship one with another,
like children's letters or numerals emptied out of
a box ; nor are they related to one another equally,
differing in similar degrees, as one does from two,
two from three, &c. ; but they fall into groups variously
related to one another, some like brothers, others like
cousins, and so forth ; whence arises the classification
of the vegetable kingdom into sub-kingdoms, classes,
orders, genera, and species.

There are two primary groups, or Sub-kingdoms of
plants; the Flowering and the Flowerless, which
differ very much indeed ; the Flowering having,
amongst other characters, usually very conspicuous
structures commonly known as flowers, which pio-
duce seeds ; and these seeds invariably contain an

8 SCIENCE PRIMERS. [n.

independent plantlet (embryo). The Flowerless plants
(ferns, mosses, seaweeds, &c.) have no such flowers,
nor such seeds : instead of seeds they have spores
which contain no plantlet, but themselves grow into
new individuals.

Plants purify the air that is being habitually
rendered unfit to breathe by animals having already
breathed it. They provide the animal kingdom with
food, and often with shelter. They protect the
surface of the earth from being too much scorched
by the sun's rays by day, and too rapidly cooled by
radiation at night. They prevent the too rapid
evaporation of the rain-fall; and they supply man
with fuel, medicine, and many materials for arts and
manufactures.

II.— GENERAL CHARACTERS OF FLOWERING
PLANTS.

1. The Vegetable Kingdom as stated above pre-
sents two quite distinct Sub-kingdoms, which the most
superficial observer rarely confounds : that of flower-
ing plants, to which trees, shrubs, and herbs belong;
and flowerless plants, such as ferns, mosses, sea-
weeds, lichens, and fungi.

The pupil is recommended to begin with the
flowering plants, not only because the two sub-
kingdoms are so different that they cannot be studied
together advantageously by a beginner in Botany, but
because the flowerless plants require for their study
high magnifying powers of the microscope and great
skill in using them.

2. Flowering plants present the following organs or

ii.] BOTANY.

parts : root, stem, leaves, flowers, which latter
are succeeded by fruit, containing seed. Most
flowering plants have roots ; all have stems, though
these may be reduced to a mere knob on the top of
the root : some few have no proper leaves, as the
dodder, and plants which, like it, feed on the juices
of others : many never have but one bud, which is a
flower-bud : but all must have a flower or flowers,
though these may be of a very simple nature.

3, The organs of flowering plants may be classed
according to their relation to one another under two
divisions : (a) an axis, of which the root is the
descending and the stem the ascending part; and
(b) appendages of the axis, which are the leaves,
and the parts of the flowers.

4. They may also be classed according to their
uses (functions) as follows : (a) for support, the
root and stem ; (b) for nourishment, the root and
leaves; (c) for reproduction, seeds, buds that
separate from the plant, flowers, fruit.

This division is evidently a very rough one ; for
while the root is often the sole organ of support,
fixing the plant to the ground and holding it upright,
other plants are supported wholly or in part by their
climbing or twining stems (convolvulus), by tendrils
(vine), by twisting leaf-stalks (clematis) and even
flower-stalks, by hooked prickles' (brambles), by sticky
glands, and in the case of water-plants by floats
containing air.

The root and leaves are the chief organs of nutri-
tion, but all green parts of the plant are so to
some extent.

The seeds are the principal means of reproducing

SCIENCE PRIMERS.

[in.

plants, but, as already pointed out, this process is also
often effected by bulbs that separate themselves (tiger-
lily) ; or by the budding of underground bulbs (onion) ;
or by tubers covered with buds (potato).

III.— THE TISSUES OF PLANTS.

5. The substance or material of which a plant con-
sists is called its tissue ; and there are several kinds
of tissue. Their nature cannot be made out without
a microscope ; but as a low power will show the
most important of them, these should be learned at
once.

6. The chief is cellular tissue (parenchyma),

FIG. i — Cellular tissue of rounded
cells, many times the real size.

FIG. 2. — Cellular tissue of rather
long cells, many times the real size.

which forms the principal substance of most plants.
It consists of minute oval sacs, called cells, crowded
together and often becoming angular by pressure
(Figs i and 2). Orange-pulp is an example of cells
loosely packed together ; cork and elder pith of cells
crowded together which have always been cohe-
rent by their sides. The walls of the sac consist

in.] BOTANY. II

usually of a very thin and transparent membrane,
which may contain air only, when the cells are dead
(as in pith) ; or a fluid, as in the cells of orange-pulp ;
or, besides fluid, granules of protoplasm (Par. n),
coloured by substances which are green in leaves, and
of other tints in many flowers; or granules of starch.
Sometimes the cell-wall is very thick and hard, as in
the stone of the cherry and other stone-fruits, and the
leathery surface of leaves such as those of the stone-

FIG 3. — Thick- walled cells from a leaf of stone-pine as seen in a cross-cut,
many times the real size.

pine (Fig. 3). Some plants are formed wholly of
cellular tissue (mosses, fungi, seaweeds, lichens), and
almost all plants have more cellular than any other
tissue. Fluids can pass through the walls of the cells,
and the nourishment which is sucked up by the roots
in the fluid state, is distributed through the plant chiefly
by passing from cell to cell. The celte which cover
the surface of the plant are a good deal flattened, and
form a layer called the epidermis.

7. Wood-tissue, of which in addition to vessels

12

SCIENCE PRIMERS.

[in.

wood is principally formed, consists of long cells, or
rather tubes, tapering and closed at both ends, with
thick walls, and which lie side by side and form wood.

8. Bast-tissue consist of very long flexible cells,
or rather tubes, also closed at both ends. It occurs
chiefly in the inner bark, and supplies the materials of
many useful fabrics. Hemp and flax are bast-cells
of the plants of those names ; and the Bast, used by
gardeners for tying, is the inner bark of the lime-tree.

9. Vascular tissue consists of long, unbranched
tubes, with thin walls, which are often dotted or

FIG. 4. — Spiral-vessels with cellular tissue on each side, many times the
real size.

barred, and sometimes thickened internally by spiral
threads, easily seen in the leaf of the hyacinth, if
broken across. These are called spiral vessels (Fig.
4). All such tubes are formed from rows of super-
posed cells, the partitions which separate them having
been absorbed.

The tissues 7, 8, and 9 usually occur together in the
form of bundles which traverse the cellular tissue, as
the veins (or nerves) of the leaves, and are called
fibre-vascular bundles.

IV.]

BOTANY.

IV.— THE

GROWTH OF CELL-TISSUE, AND
NATURE OF THE CELL.

10. To understand how plants grow, and how such
products as sugar, starch, oils, resins, and medicinal
substances are formed in them, it is necessary to ex-
amine further cellular tissue ; for it is by the addition
of cell to cell that plants grow, and by chemical
changes taking place within the cell, that the above-
named and other substances are formed.

11. The cell consists of a wall (cell- wall) and its

FIG. 5. — Growing point of stem of stonewort showing formation of new
cells by division, many times the real size.

contents (cell-contents). The cell-wall is a thin (rarely
thick) transparent bag of inert or dead matter called
cellulose ; it contains when young a viscid granular
substance endowed with life and sometimes exhibiting
motion, called protoplasm. Cellulose is composed

14 SCIENCE PRIMERS. [iv.

of oxygen, hydrogen, and carbon ; protoplasm of
these together with nitrogen.

12. When cells are very young they are smaller
in size, the cell- wall is thinner, and they are completely
filled with the protoplasm ; a darker rounded portion
of this is generally to be noticed in the centre and is
called the nucleus. As the cells grow in size their
cavity becomes larger than the mass of protoplasm
which originally filled it. The cell-wall is always
lined by a layer of protoplasm, but in the interior of
the cell, cavities are formed in the protoplasm which
are filled with a watery fluid called the cell-sap. Later
on the protoplasm is reduced to a thin film, in which
the nucleus is placed and which lines the cell-wall ;
strings of protoplasm pass from the nucleus across the
cell-cavity. In old wood and cork cells the proto-
plasm has completely disappeared, and the cavity of
the cell contains nothing but water or air.

13. New cells are formed by the protoplasm of
some which are still quite young dividing into halves,
between which a wall of cellulose is then formed.
The original cell-cavity is thus divided into two. It
is supposed that this breaking up of the protoplasm
commences by the division of the nucleus seen in the
protoplasm of most cells, and that the protoplasm
collects round each half of the nucleus ; but this is
not certain.

14. The rate at which cells thus multiply is asto-
nishing, and is most conspicuous in mushrooms, toad-
stools, &c., which are formed wholly of cellular tissue.
The giant puff-ball grows in one night from the size of
a marble to that of a child's head, by the growth and
increase of cells, which individually are but a few

iv.] BO 7^ ANY. 15

thousandths of an inch in diameter, and of which three
millions are estimated to be formed in twenty-four
hours.

15. Cells which have ceased to divide gradually
grow into their permanent form, which in various cases
is very different.

(a) Those of cork and pith do not alter very much
in shape, and finally, losing their protoplasm and cell-
contents which are absorbed into more active adjacent
cells, simply contain air.

(b) Wood and bast-cells grow very much in length.
The protoplasm continues to secrete cellulose which
is added to the cell-wall and gradually makes it very
thick (see Par. 6). These, too, lose eventually their
living contents and contain only air or water. Other
cells may have their walls thickened in the same way
without becoming elongated. Vessels (Par. 9) are
formed by the partitions between rows of superposed
cells becoming absorbed.

(c) In many cases the protoplasm, instead of
secreting thickening material which is added to the
cell-wall, forms various substances out of the fluids
which permeate through the cell-wall and mix with the
cell-sap. These remain imbedded in the protoplasm,
as in the case of starch grains, oily and fatty matters,
or grains of albuminoids ; or they are dissolved in the
cell-sap, as in the case of sugar and the substances
(alkaloids, &c.) which give so many plants useful or
noxious properties.

(d) These substances often seem to fill the cell-
cavity to the exclusion of everything else, but the
remains of the protoplasm can generally still be traced,
though in a, very shrivelled state.

3

1 6 SCIENCE PRIMERS. [iv.

(e) In the green parts of plants the protoplasm
undergoes a peculiar change, by which it is broken up
into granules which contain the green colouring
matter (chlorophyll). These granules are accordingly
termed chlorophyll granules.

1 6. Chlorophyll granules, consist then of proto-
plasm coloured green by a pigment called chloro-
phyll. They abound in the superficial cells of plants,
and their colour being seen through the thin cell-walls,
give the green hue to leaves ; similar granules tinged
with other colours give in some cases the bright
tints to flowers. Chlorophyll under the influence
of sunlight brings about changes in the cells of the
leaf that result in starch being formed and distributed
all through the plant, as required. In so doing, it
is supposed that the chlorophyll separates the carbon
from carbonic acid taken from the air, gives back
the oxygen to the air, and supplies the carbon (which
at the same time combines with the components of
water to form starch) to the plant. It is a curious
fact that chlorophyll is not developed, and there-
fore that this process will not go on, except the
plant be supplied with iron ; and as all soils contain
iron> the plant can always take this substance up
by its roots. In the absence of sunlight also, the
green colour of chlorophyll does not appear, hence
celery is covered up to make it white, otherwise it is
a very green plant.

17. Starch. — This compound of carbon, hydrogen
and oxygen abounds within the cells of many parts
of many plants, as the potato and all cereal grains,
arrow-root, tapioca, sago, &c. It consists of white
granules, differing in form in different plants (Fig. 6),

IV.]

BOTANY.

often marked* with concentric rings, and is tinged
bright blue with iodine. It is found in greatest quan-
tity in the parts of plants intended to be deposits
of food during winter, for the growth of the plant
in the following spring. Seeds and roots, as they
grow, use up the starch which the cells contain.

FIG. 6. — Starches. Granules of a Potato, b Wheat, c Oats, d Maize ai d
Rice, e Bean and Pea, f Parsnip, g Beet ; all very many times their real size.

18. Oils and fats are composed of the same
elements as starch, from which they are probably
manufactured by the plant, and as deposits of food
serve the same purpose. Oils prevail in seeds and
fruits, as linseed oil (from the seed of the flax -plant),
cocoa-nut-, almond-, olive-, colza-, and castor-oils.

19. Sugar, formed also of the same elements,
differs from all the preceding in being soluble in
water, and existing only in solution. It abounds in
the cells of sugar-cane, beet, parsnip, and all sweet
fruits. It is formed out of the starch manufactured
in the leaves.

20. Albuminoids. — These are compounds con-
taining nitrogen in addition to carbon, hydrogen, and

1 8 SCIENCE PRIMERS. [iv.

oxygen. Gluten, the most common oY them, occurs
in granules in the outer cells of wheat and other
grains. The viscid matter left in the mouth after
chewing wheat, especially hard wheats, is gluten.

21. Alkaloids. — These are very remarkable sub-
stances, which all contain nitrogen; many of them
are medicines, as quinine and morphia ; others are
poisons, as strychnine and nicotine ; still others have
stimulating properties, as theine and caffeine, to which
tea and coffee owe their refreshing qualities.

22. Other substances, of a mineral character,
enter into the composition of the cell and cell-
contents ; as sulphur, which is a constituent of the
albuminoids ; iron which, as already stated, is indis-
pensable for the production of chlorophyll; silica,
which is found deposited in the insoluble state
within the cell-walls ; compounds of phosphoric acid,
which are associated in some way not understood
with the formation of albuminoids; and lastly, salts
of potash, which are concerned in a manner equally
unknown with the production of starch and sugar.
Other mineral constituents are found in the plant,
often in considerable quantity, such as salts of soda
in seashore plants. But this is due to their acci-
dental presence in the soil ; and marine plants
grown inland will usually flourish with very little
soda. Calcium, again, is very commonly present in
plants, being taken up from the roots as sulphate of
calcium. This, however, is decomposed by oxalic acid,
and oxalate of calcium, which is not readily soluble, is
formed, and this is deposited in the plant in the form
of crystals, while the sulphuric acid yields its sulphur
for the formation of albuminoids : these occur in

IV.]

BOTANY.

the cells of a walnut leaf (Fig. 7), and in rhubarb
(Fig. 8), and beet (Fig. 9).

FIG. 7. FIG. 8. FIG. 9.

Crystals of oxalate of lime, as found in cells, many times the real size.

23. The great importance of the nitrogenous sub-
stance protoplasm, as the only living matter which the
plant contains, cannot be too firmly insisted upon.
It is of the same nature as the protoplasm of which
some of the lowest animals (those nearest the plants)
wholly consist, and which forms the living substance
of the bodies of the higher animals, including man
himself.

Like animals, plants cannot live without oxygen.
The activity of the protoplasm in both cannot be kept
up without it. The protoplasm of all living things
wastes and would die altogether unless it were
nourished. This process of nourishing involves
respiration, i.e. getting rid of superfluous carbon,
which combines with oxygen taken in from the air,
and is given off as carbonic acid (Par. 158).

20 SCIENCE PRIMERS. [v.

V.— THE FOOD OF PLANTS.
ABSORPTION, TRANSPIRATION, ASSIMILATION.

24. The food of plants is partly gaseous and partly
liquid; and is derived from the earth or water in
which they grow, and from the air. The liquid food
is taken into the plants chiefly by their roots, the
gaseous chiefly by their leaves.

25. The gaseous food of plants consists of car-
bonic acid gas, supplied chiefly by the atmosphere.
The liquid food is water, in which various saline
substances are dissolved, the principal components of
these being nitrogen, phosphorus, sulphur, potash,
and iron. The above-named matters are found in
most soils in which plants grow, but cannot be taken
up by the roots except they be dissolved in water.

26. Absorption. — The taking in of liquid food
by the roots is called absorption, and the liquid
absorbed becomes part of the sap in the plant. The
sap ascends through the stem and branches, and so
reaches the cells of the leaves, or the cells near the
surface of plants that have no leaves. In mounting
up it passes both from cell to cell through their walls
and along some of the tubes of the vascular tissue.

The taking in of carbonic acid gas from the air is
another process of absorption. It is performed by
the leaves, in the cells of which a chemical process
goes on under sunlight, by which the carbon is broken
up. the carbon being retained by the plant, and the
oxygen given back to the air. The carbon being at
the same time combined with the oxygen and hydrogen

v.] BOTANY.

of water as already explained (Par. 15, c\ the substance
known as starch is formed.

27. Transpiration. — The sap, on reaching those
surfaces of plants that are exposed to the light, parts
with a great deal of its water as vapour, either
through minute pores in the leaves, or through the
walls of the superficial cells, as in the case of plants
that have no leaves. These pores are called stomates
(Par. 72) • they exist in very great numbers, chiefly on
the underside of the leaves; an apple-leaf presents
upwards of 100,000 of them. This process of evapo-
ration, called transpiration, keeps plants cool in the
hottest weather, and is so rapid that a sunflower plant
has been found to give off a quart of fluid in twenty-
four hours, and an oak or beech-tree must give off
many gallons in the same space of time.

28. Assimilation. — The process by which the
carbonic acid absorbed by the leaves and the water
absorbed by the roots are combined together in the
leaves under the influence of sunlight to form starch,
free oxygen being at the same time given off, is called
assimilation. The starch so formed appears to be
dissolved in the cell-sap during darkness, and to be
distributed from cell to cell all over the plant. It is
used up wherever growth is taking place, furnishing
the material for the formation of the cellulose of the
new cell-walls, or it is stored up again in the solid
form as a reserve of material for future use, as in seeds.
Besides conversion into cellulose, starch is capable of
being transformed under the influence of protoplasm
into oily and fatty matters, and also into sugar.

The soluble starch in its downward passage through
the tissues of the stem, meets with various saline

22 SCIENCE PRIMERS. [v.

matters containing nitrogen, such as nitrates or salts
of ammonia. From these in some way or other not
yet understood, but under the influence of protoplasm,
the nitrogen is abstracted, and from this, together
with the constituents of starch, albuminoids are
manufactured.

These albuminoids are the necessary food of proto-
plasm. It is important to remember that their
formation depends upon the manufacture of starch in
the green parts of plants, and this depends upon expo-
sure to sun-light. We see, therefore, why without light
plants starve; their protoplasm ceases to be nourished.

29. The effect of plants requiring mineral sub-
stances for their nourishment is, that one kind of crop
cannot be grown continuously on the same piece of
ground, if it is periodically cut and carried away.
This has led to the use of manures containing the
substances taken away in the crop, for rendering the
exhausted soil fit for another crop of the same kind.
In a state of nature, on the contrary, the plants of
each piece of ground die where they grow, and by
decay give back to the soil what they took from it.

30. The above-mentioned plant-foods are all
inorganic substances ; and until quite recently plants
(except fungi and parasites) have been supposed to be
incapable of deriving nourishment from organic sub-
stances except these be completely decayed. It is
now, however, ascertained that some plants can derive
nourishment from raw meat, insects, and other animal
and even vegetable matter, such plants being provided
with organs for the purpose of digesting such matters.
The leaves of the nepenthes, side-saddle flower,
venus's fly-trap, and sundew, are instances. In all

vi.] BOTANY. 23

these cases where the meat is laid on the digesting
surface, a fluid is poured out from its cells which
acts as a solvent on the animal substance, enabling
the plant to absorb it and use it for its nourishment.

31. Except in cases of accident, plants in a state
of nature either die a natural death, that is, one that
comes after the functions of all its organs have been
fulfilled, or are eaten by animals. Those that die
a natural death undergo chemical changes which
constitute decay, and in so doing return to the air
and earth the materials of which they were con-
structed. Those that are eaten by other animals
undergo quite a different set of chemical changes in
the animal's body, and which may be said to result
in the several constituents of the plant supplying
nitrogenous substances to the animal's muscle, carbon
to its fat, mineral matter to its bones. These, or
some of these, are necessary to the life and health
of every animal, and are what it cannot obtain from
simple inorganic substances except these have been
first taken up by plants and united together into more
complicated compounds.

VI.— THE GROWING SEED.
GERMINATION.

32. It is well to commence the actual study of
plants by that of the growth of the seed, as it is very
easily observed, and a right understanding of the early
history of the plant as studied in its seedling state is
a great help to the learner of its later history.

33. Take seeds of pea, mustard, and wheat, and
place them on dry earth. So long as earth and seeds

SCIENCE PRIMERS.

[vi.

remain dry the seeds will not grow. Moisten them
and put them where the temperature does not rise
above freezing ; still they will not grow. Place them
in a vessel from which all air is excluded • still they
will not grow. Lastly, place them where the tem-
perature is considerably above freezing, and where
air has access to them, and keep them moist, and
they will grow, whether in light or shade. This
growth of a seed is called its germination.

34. From these experiments we learn that to produce
germination in a live seed, water, air, and a heat con-

FIG. 10. — T Pea, 2 Radicle pushing through Integument, 3 Embryo with

Radicle elongated, 4 the same with one Cotyledon removed, 5 the same

further advanced ; all twice the real size.

siderably above the freezing point are all required.
And what is thus proved of the seed applies to plants
throughout their lives — namely, that to grow they

VI.]

BOTANY.

must have warmth, air, and moisture. Further on it
will be shown that to grow to maturity light is also
wanted ; but at present we are concerned only with
the germinating seed.

35. From experiment now proceed to observation.
All seeds consist of two principal parts — a dead part
outside and a living part within it. The living part
is the plantlet, or embryo, and is in fact an im-

FIG. ii.— Germination of Mustard, i Seed, 2 Embryo removed from Integu-
ment, 3 Radicle pushing through Integument, 4 Cotyledons and Radicle after
throwing off Integument, 5 Young Plant ; all twice the real size.

mature plant, having a separate existence from that of
its parent : the dead parts are its coverings (integu-
ments), together with sometimes a nourishing matter
(albumen) provided for the plantlet, and like it con-
tained within the integuments. The pea and mustard
have no albumen ; the wheat has.

26

SCIENCE PRIMERS.

[VI.

36. The plantlet consists of several parts, which
serve different purposes. In the pea (Fig. 10) it
consists of two thick masses (cotyledons) placed
face to face and united at one point of their margins.
A small cylindrical body lies between the cotyledons
where these unite, and is attached to them about
its middle. It is conical at one end, and blunter

FIG. 12.— Wheat germinating : i Seed cut vertically, showing— a the in-
tegument, b the albumen, c the embryo ; 2 the same further advanced ; 3 back
view of grain, with d plumule, and e sheathed rootlets ; 4 the same further
advanced ; all twice the real size.

at the other. When the seed grows, the conical
end (the radicle), which lies below the point of
junction with the cotyledons, elongates downwards
and gives origin to the root of the plant. The
blunter end (the plumule), which lies above that
point, elongates upwards and becomes the stem of

vi.] BOTANY. 27

the plant; the scales are undeveloped leaves. To
ascertain which is the radicle and which the plumule
of the plantlet, the seed must sometimes be examined
soon after it has germinated, when they are easily
distinguished, whether by their form or by the direc-
tions they take.

37. This elongation of plumule and radicle is the
first growth made by both the pea and the mustard
but after this they follow quite different modes of
development.

In the case of the pea the cotyledons do not grow
at all, but supply nourishment to the growing radicle
and plumule, which absorb it through the points of
union ; after which, their nourishing matter being ex-
hausted, the cotyledons shrivel and dry up, or rot.
The plantlet thus feeds on the same substance as is
eaten at table, and in so doing it empties the cells of the
cotyledons of the starch, oils, albuminoids (Sect. 17 to
20) which they contained. Here, then, the cotyledons
nourish the plumule and radicle from the very first.

In the case of the mustard, on the other hand,
whilst the radicle plunges into the soil, the coty-
ledons are carried up above ground, where they
spread out to the light, become green, and assimilate
for the plantlet, as leaves do for full-grown plants.

38. In the wheat (Fig. 12), the plantlet lies on one
side of the seed, between its integument and the albu-
men, which is white and floury. It has not two oppo-
site thick cotyledons, but one, which forms a sheath
around the other leaves of the plumule. When germi-
nation begins, the plumule and radicle absorb nourish-
ment from the albumen by contact, and not through a
connecting structure such as that which unites the

4

28 SCIENCE PRIMERS. [vii.

plumule and radicle of the pea to its cotyledons.
The plantlet here feeds on the flour of which we make
bread, just as the pea plantlet fed on the part of the
pea which we eat.

The radicle of the wheat does not elongate upon
germination, as that of the pea and mustard did, but
rootlets grow out from it with sheaths at their base.

39. These great differences between the cotyledons,
the growth of the root, and the mode of germination
of the pea (or mustard) and of the wheat, are most
important, being characteristic of the two great divi-
sions (classes) of flowering plants, called Dicotyle-
dons (plants with two cotyledons or seed-leaves) and
Monocotyledons (plants with one cotyledon or
seed-leaf), which divisions are further to be recognized
by other characters hereafter to be described.

VII.— THE ROOT.

40. The root is formed by one or more pro-
longations of the radicle of the embryo (Sect. 36).
Its uses to the plant are, to fix it to the ground, to
absorb nourishment from the latter, and sometimes
to store up and retain nourishment during winter for
the food of the plant during its growth in the following
spring.

41.. Roots are known from stems by their growing
downwards from the plantlet (Sect. 36), and usually
afterwards avoiding the light ; by their not, or very
rarely, bearing buds; and by their structure and mode
of growth.

42. When only a single prolongation of the radicle
is formed this is called a tap-root. This bears at its

VII.]

BOTANY.

29

side numerous slender branches or root-fibres.
Sometimes the tap-root is very insignificant and not
easily distinguished from its fibre-like branches ; the
whole root is then distinguished as fibrous. Root-
fibres are usually so slender that it is not easy to
see their nature ; but this can be done in the hyacinth
root, the tip of which, if cut down the middle shows

FIG. 13. — Vertical section of tip of Root-fibre of Hyacinth, many times the
real size.

under a microscope that a sheath of soft flattened cells
envelops the tip, within which is a mass of denser
cells which form the growing point.

43. Root fibres do not push themselves into the
soil as one thrusts a stick into it ; but they push their
way through interstices in the soil as they elongate
at the point As the root fibre elongates, the front
part of the sheath decays, and the back part, which
is constantly renewed by the growing point, takes
its place ; thus advancing and displacing water in
the case of the hyacinth, and earth in other cases.

In shrubs and trees the root-fibres as well as the
tap-root thickens as it grows, becomes woody, and
displaces the earth laterally as well as in front ; and

SCIENCE PRIMERS.

[VII.

with such force does growth go on that it is common
to see stones of walls displaced by roots. In tropical
countries the destruction of buildings is universally
caused by the power of growing roots ; and neither
conquering nations, nor earthquakes, nor fires, nor
tempests, nor rain, nor all put together, have de-
stroyed so many works of man as have the roots
of plants, which have all insidiously begun their work
as slender fibres.

44. Nourishment is taken in by the root-hairs,
but not by the growing-point. Root-hairs are delicate
long cells, that stand out from the surface of the
elongated radicle and of the root-fibres, and may be
seen on the first formed root of the pea and mustard
plants in great quantities.

FIG. 14. — Root-hairs, many times the real size.

4.5. Roots may be roughly classed under two heads
— those that simply nourish the plant as it grows, and
those that lay up a store of nourishment to assist the
growth of the plant during the second year.

To the first class belong (a) the very simple annual

yii.] BOTANY. 31

roots that consist wholly of simple fibres (hyacinth; ;
(b) annual roots of much branched fibres (grasses,
groundsel, shepherd's purse) ; (c) branched roots whose
fibres become woody in the second year (trees, shrubs,
and herbs with woody roots).

To the second class belong (a) such roots as
are fleshy and globose or spindle-shaped (turnip,
carrot, radish, beet). These produce leaves the first
year, and in the second, leaves, flowers, and fruit,
after which the whole plant dies. They are nourished
by slender fibres from their sides and tip. (b} Roots
with many fleshy branches, called tubercles (ficaria,
dahlia), (c) Roots with only two fleshy tubercles like
the orchis, which deserves a separate description.

46. The root of an orchis consists of two distinct
fleshy tubercles, one large, the other small. Both

FIG. 15. — Tubercles and Root-fibres of Orchis.

grow at the bottom of the stem, below the stout root-
fibres which spread horizontally from just above them.
When an orchis is in flower, the flower-stem proceeds
from the top of the large tubercle, which bears the
smaller tubercle attached close to its neck. Later in

SCIENCE PRIMERS.

[vii.

the year, when the orchis is seed-bearing, the large
tubercle will be found withered, and the little tubercle
to have grown large and plump, and have a bud at
its top. Still later, the whole plant dies, except the
smaller tubercle with its bud, which latter will grow
up as the orchis stem of the next year. An English
orchis plant is thus a travelling store of food, which
makes a little journey annually; but in Australia certain
orchises make a much longer annual journey, for the
new root-tubercle, instead of being attached to the
base of the stem close to the old root-tubercle, is
attached to the latter by a root-fibre sometimes six
inches long; and such orchises make comparatively
rapid marches under the ground.

47. Adventitious Roots. — Root-fibres may in
some cases be thrown out from the stems of plants.

FIG. 16 — Creeping stems and roots of Couch-grass.

Such rootlets are called adventitious, and are found
on mature plants of both Monocotyledons (stem of
couch-grass near the ground), and of Dicotyledons
(wall-roots of ivy), and they form the supports of the
branches of the banyan-tree of India.

VIIL] BOTANY. 33

VIII.— THE STEM.

48. The stem is formed by the elongation of the
plumule of the embryo (Par. 36); its uses are to
support the leaves, buds, and flowers, and to form a
channel of communication by which the water absorbed
by the roots is conveyed to them, and the starch
formed in the leaves is distributed over the plant.

49. The stem usually seeks the light, but not always;
for many stems grow underground, elongating, and
even branching horizontally; such stems (cowslip,
potato) are often mistaken for roots, from which they
differ in their mode of growth, and in bearing leaves,
buds, and flowers.

50. A fully developed stem may be simple (most
palms) or branched. It consists of nodes and
internodes : the nodes are the points from which
leaves arise ; the internodes are the intervening por-
tions of the stem or branch. The nodes are swollen
in many plants (pinks, grasses); in grasses the inter-
nodes are usually hollow while the nodes are solid.

51. The chief modifications of the stem besides
the common erect one are —

The twining stem (hop, honeysuckle, convol-
vulus), of which some turn to the right, some to the
left; but very rarely does one kind of plant turn
either way indifferently. This twining habit is the
effect of an inherent disposition in the tips of all
elongating stems to bend successively towards all the
points of the compass; a movement which is very
obscure in plants with straight stems, but very marked
in those that climb. The tip of such a stem, as it
elongates, describes a wider and wider sweeping circle,

34 SCIENCE PRIMERS. [vin.

till the stem strikes a support, when the portion
above the point of contact with the support continuing
to revolve as it lengthens, naturally twines round and
ascends it. Such stems, if they find no support,
become weak as they lengthen, and fall on the ground.

52. The principal underground forms of stem are —
(a) The bulb, a very short, usually underground

stem, with excessively crowded, overlapping leaves.
These leaves are wrapped round one another in the
onion, but simply overlap in the tiger-lily.

(#) The rhizome or root-stock, a woody under-
ground stem, which sends root-fibres from its lower
side, and buds and leaves from its upper side (iris).
The corm is a very short fleshy rhizome (colchicum).

(<:) Bulbils are small bulbs or corms formed at
the side of old ones, and are hence analogous to
branches, under which they will be further noticed.

53. The tissues of the stem of flowering plants are
arranged on two plans, one characteristic of Dicotyle-
dons, the other of Monocotyledons (Par. 39). These
plans must be understood by the pupil, and can be so
by a little patience and practice with specimens ; they
are best illustrated by three such examples as the flax,
lime, and butcher's broom, or asparagus.

54. The flax plant (a Dicotyledon) has an erect her-
baceous stem of many internodes (Par. 50), with leaves
all the way up, and flowers at the ends of the branches.

A magnified cross-cut of the stem shows that it
consists of a cylinder of cellular tissue (Par. 6), traversed
vertically by a ring of wedge-shaped fibro-vascular
bundles (Par. 9), which are separated from one
another by the cellular tissue. The central cellular
tissue is the future pith, that at the circumference is the *

VIII.]

BOTANY.

35

future outer bark, and that between the fibro-vascular
bundles is the future silver-grain of wood. The
fibro-vascular bundles are in part future inner bark
and in part future wood, and consist of wood-tissue
(Par. 7) mixed with vascular tissue (Par. 9) towards
the centre, and of bast-tissue (Par. 8) towards the
circumference. Of these components of the vascular
bundle the bast-tissue forms the inner bark; the
wood and vascular tissues form the wood of the plant.
Such is the origin of outer bark, inner bark, wood,
pith, and silver-grain.

A cross-cut of a one year's old twig of lime shows
the same arrangement of tissues as the flax; but
whereas the flax stem dies the same year as that
in which it is formed, the lime twig lives through the
winter, and is added to during the following summer,
increasing thus in thickness.

FIG. 17. — Transverse section of vas-
cular bundle from stem of a Dicoty-
ledon.

FIG. 18.— Transverse section of stem
of a Dicotyledon.

55. This increase of thickness is caused by new
tissue being added between the bast and wood formed
in the previous year. This new tissue consists at first
of soft, tender, cellular tissue, produced by the growth

36 SCIENCE PRIMERS. [vm.

of the cambium layer (which lies between the bast
and the wood) in spring, in the position indicated;
and which after the leaves expand, and are acted upon
by light and heat, gives rise to an additional layer of
new bast-tissue inside the old bark, and new wood-
tissue with vascular tissue amongst it outside the old
wood.

56. Omitting details (such as the formation of layers
of cellular tissue outside the bast-tissue), this is the
plan upon which the stem and branches of all plants
with- two cotyledons are formed. It has been called
Exogenous growth, because the bulk of the stem is
increased by additions to the outside of the wood.
Exogenous plants are hence synonymous with Dicoty-
ledons (Pars. 39, 53).

57. The branch or stem of a dicotyledonous tree
or shrub (as the lime) if more than one year old, hence
consists, proceeding from the centre, of (a) pith ;
(b) layers of wood (with a little vascular tissue), of
which the oldest layers are next the pith ; (c) layers
of bast-tissue, of which the oldest are next the cir-
cumference ; (d) layers of cellular tissue, of which the
oldest are next the circumference ; (<?) rays of cellular
tissue stretching from the pith to the circumference.

58. The pith of the centre never grows after the
first year ; but the cellular tissue of the outside of the
bark often grows by annual additions between it and
the bast layers, and of that the barks of the cork,
plane and birch trees afford conspicuous examples.

59. The stem or branch of the butcher's broom,
or asparagus (Monocotyledons), has a totally different
structure. A cross-cut shows that the whole consists
of a cylinder of cellular tissue, traversed by isolated

viii.] BOTANY. 37

bundles of nbro-vascular tissue (Pan 9), not arranged
in a ring, or in concentric rings, but scattered without
order through the cellular tissue, and much crowded
at the circumference of the stem. Each of these
isolated bundles consists outwardly of bast-cells and

FIG. 19. — Transverse section of stem of a Monocotyledon.

inwardly of wood-cells, exactly as in the first year's
stem of flax or lime (Par. 54). These bundles do
not, however, increase by the addition of bast-cells
and wood-cells.

60. Commencing at the bases of the leaves, all the
fibro-vascular bundles of a Monocotyledon may be
traced downwards, first arching inwards towards the
centre of the stem, then gradually outwards to its cir-
cumference, where they are closely crowded. There
is hence no true bark, though sometimes the cellular
tissue surrounding the vascular bundles forms a separ-
able outer layer, as in the dragon-tree (Dracaena), in
which also new bundles are formed which are disposed
in concentric rings as in Dicotyledons (Par. 56). In
all cases, however, the individual bundles are not
added to as in Dicotyledons, and they are hence called
definite bundles.

SCIENCE PRIMERS.

6 1. The arrangement of vascular bundles above de-
scribed is characteristic of Monocotyledons (Par. 39).

IX.— BUDS AND BRANCHES.

62. Buds are formed in autumn, either at the ends
of stems and branches, or at the angle where the leaf
or leaf-stalk meets the stem, and remain dormant till
spring. They have wood, pith and bark continuous
with those of the stem, with which their union is
hence complete. They are usually protected from
cold and wet by scales that are often covered with
gum or with hairs.

'Fie. 20. — Leaf-buds and vertical section of ditto.

Some plants increase only by terminal buds (willow,
elm); others by both terminal and axillary buds (horse-
chestnut, ash, and most trees).

63. Buds become leafy branches by the develop-

ix.] BOTANY. 39

ment of their internodes (Par. 50), and may produce
leaves only, or flowers, or both ; or they may in some
rare cases fall away from the plant (tiger-lily), and
form new plants, sending roots downwards and stems
upwards.

If the terminal bud produce only an inflorescence
(Par. 75) its onward growth is stopped, and lateral
buds form below it and are developed into.permanent
branches. This takes place in the horse-chestnut
and lilac, and gives an angular character to their
branching. In many half-woody plants, the branches
grow on indefinitely till killed by the winter's cold,
when buds form low down on the stem which develop
similar branches in the following spring.

64. Buds may, instead of simply elongating into
branches, grow in width and form short fleshy tubers,
of which the potato is an example. A careful exami-
nation of a potato plant shows that it consists of an
underground branched ascending stem, which bears
root-fibres, and shortened fleshy tuberous branches
(the potatoes), covered with eyes, which are buds in
the axils of undeveloped leaves. The bulbils at the
side of the bulb of a hyacinth or crocus are buds.

65. The tendrils of the Virginia creeper are modi-
fied branches whose divisions expand at their tips
into glue-tipped suckers, that fix the branches to the
wall. The tendrils of the grape-vine are also branches
with spirally-twisted thread-like divisions, which on
finding a support twine round it, following the same
course as twining stems (Par. 51). The spines of
most plants are stiff shortened branches (hawthorn,
sloe). (Prickles are quite different things, and will be
explained in Par. 138 (e).)

5

40 SCIENCE PRIMERS. [x.

66. The branching of trees forms a most admirable
winter study, and one full of interest. It is sufficient
to allude to the zigzag branchlets of the oak, with
rounded terminal buds ; the graceful, straight twigs of
the beech, with lancet-shaped buds ; the bold stout
branchlets of the horse-chestnut, with ovoid buds; and
the exquisite subdivided sprays of the elm, like lace-
work against the sky. All these characteristic fea-
tures are due to the form, direction, and setting on of
terminal twigs and buds, and are objects of equal
interest to the botanist and the artist. Leafless
branches of the common English trees suspended
against a white wall are capital studies for pupils, and
reveal characters that escape the observation of
teachers whose attention has not been called to them.

X.— LEAVES.

67. Leaves are expansions of the cellular-tissue of
the stem traversed by nbro-vascular bundles (Sect. 9).
Their use is to afford a large surface for exposing to
the action of sun-light and heat the food absorbed
by the plant and thus cause assimilation (Par. 28) ;
they also provide for evaporation (Par. 27) ; and they
absorb the carbonic acid of the air (Pars. 26, 28).

68. The external characters of leaves are very
various indeed, and are characteristic of whole groups
as well as of individual kinds of plants. The following
principal facts regarding the leaves of some common
plants should be observed by the pupil :—

(a) As to duration. Whether they are deciduous,
falling annually; or persistent, continuing a year or
longer.

x.] BOTANY. 41

(b) As to position. Whether in opposite pairs
(dead-nettle, maple, horse-chestnut); or alternate (lime,
ivy, grasses) ; or whorled (woodruffe, bed-straw) ; or
tufted (larch, cedar, pine).

(c) As to insertion. Whether by a stalk (petiole)
(lime, &c.). or not (sessile), or by a sheath (grasses) ;
and whether the petiole is inserted at the bottom of
the blade, as in most plants, or in the centre, as in
the penny-wort

(d} As to division. Whether simple (lime, ivy,
oak), or compound — that is, formed of separate
pieces (leaflets), (ash, horse-chestnut, rose, pea,
bean).

(e) Whether their margin is entire (privet) ; or
serrate, with teeth pointing upwards (lime) ; or
toothed, with teeth pointing outwards (holly) ; or
lobed (ivy, oak) ; or cut (hawthorn) ; or pinnati-
fied, cut on each side to the middle (dandelion) ;
or multifid, cut repeatedly into little segments
(parsley, milfoil).

(/) Whether stipulate — that is, having append-
ages at the base of the petiole (c) called stipules,
which may be persistent (rose, pea, heartsease), or
deciduous, that is, soon falling away (apple, oak,
beech; ; or if they are ex-stipulate, having no
stipules (privet, box).

(g) If compound (d}. Whether the leaflets (d) are
digitate, spread out like the fingers (horse-chestnut) ;
or pinnate, having the leaflets in opposite or alter-
nate pairs, in which case there is sometimes a terminal
leaflet (ash), and sometimes none (pea).

(/i) Other characters, relating to form, texture, sur-
face, colour, smell, are too numerous and detailed to

42 SCIENCE PRIMERS. [x.

be employed as exercises for the observation of the
beginner, who should be able to apply all those terms
mentioned above to the trees and shrubs of his
county.

69. The way in which leaves are folded together,
or doubled up, or rolled up in bud, is called their
vernation, and is an excellent subject for the pupil's
observation. Thus, in grasses and in the cherry they
are simply rolled round one another ; in the apple
they overlap in opposite pairs ; in the flag they are
sharply folded upon one another ; in ferns they are
rolled inwards from the top like a crozier \ in the
pear and apple the margins of each leaf are rolled
inwards, and in the rosemary and the willow the
margins are rolled backwards ; in the vine, beech, and
gooseberry, each leaf is plaited.

70. The chief substance of all leaves is cellular
tissue (Par. 7), continuous with that of the stem. The
cellular tissue is traversed by fibre-vascular bundles
(Par. 9), also continuous with those of the stem. The
leaf tissues are thus, like those of the bud (Par. 62),
in complete union with those of the stem.

71. A cross section of a leaf shows, beginning at
the upper surface (a\ a delicate skin (epidermis)
(Par. 6) of flattened transparent cells ; (b) a layer of
close packed cells full of green chlorophyll granules
(Par. 1 6); (c) several layers of loosely packed cells with
air-spaces between them ; (d] an epidermis similar to
that of the upper surface.

The vascular bundles consist of bast- tissue towards
the under surface of the leaf, and wood-tissue, with
vascular tissue, usually consisting of spiral vessels,
towards the upper surface.

X.]

BOTANY.

43

72. The epidermis is studded with breathing pores,
stomates (Fig. 21), which usually consist of two
sausage-shaped superficial cells inclosing an oval
orifice. The stomates of most plants open more
widely in the light than in the dark, and this must
have the effect of promoting evaporation (Par. 27).

nwn

FIG. 21. — Fragment of Epidermis with a Stomate.

The glass-like sheen of the surface of leaves is due
to the texture and transparency of the epidermis under
which the cells full of green chlorophyll granules are
seen (Par. 16).

73. The venation, or arrangement of the vascular
bundles in the leaf, is for the most part very different
in Dicotyledons and Monocotyledons. In the former,
one or more vascular bundles enters the petiole (or the
leaf itself if sessile), and usually either runs to the end
of the blade as a mid-rib, or sends a branch into each
division of the leaf ; while from each side of this mid-
rib branches are given off that branch again, and by
uniting form a network. In most Monocotyledons
either many vascular bundles enter the leaf and run

44 SCIENCE PRIMERS. [x.

lengthwise through the blade, meeting at its tip, or
one such bundle splits up at the base of the leaf into
many that run as above ; in most Monocotyledons
these main bundles are connected by straight trans-
verse bundles. To these rules there are exceptions,
but they are sufficiently constant to make it always
worth the while to examine the venation of a leaf
together with the characters given in Pars. 39, 53,
and 60, when referring a plant to one of these two
classes.

74. The death and separation of the leaf previous
to its fall from the parent plant are not accidental,
but due to the following causes : —

First, and chiefly, because there is developed at
the base of the leaf, or its stalk (if it has one), a
transverse layer of cells destined to die after the leaf
has performed its functions and before any other
part of the leaf does so. The leaf consequently falls
off, leaving a clean scar. Secondly, because the leaf
rapidly acquires in spring its full size, whilst the branch
on which it grows goes on thickening ; consequently,
the tissues at the point of union tend to become
disunited. Thirdly, because the fluids taken in by
the root go to the leaves ; these fluids contain earthy
matter, most of which is deposited in the leaf
tissues, choking them, preventing them from per-
forming their functions, and hastening their death.
This is proved by burning spring leaves, which yield
little ash, while autumn leaves yield more even than
wood does. It is however remarkable that the sub-
stances contained in falling leaves are those which
have ceased to be of value to the plant. The starch
and protoplasmic substances, together with the most

XL] BOTANY. 45

important mineral matters such as phosphoric acid
and potash, are transferred to the permanent parts of
the plant before the leaves fall.

XI.-INFLORESCENCE.

75. This term denotes the arrangement of the
flowers on the stem or branch of a plant, which
follows several very distinct plans.

76. The simplest inflorescence is that of a one-
flowered plant, like the tulip, whose flower-stalk,
peduncle, is terminal ; the next is such as the
pimpernel or dog-violet, whose single flowers spring
from the axils of leaves. When the peduncle is many-
flowered, the form of inflorescence depends on the
arrangement of the partial flower-stalks (pedicels)
upon the peduncle, and the order in which they open.

77. The order in which the flowers open on the
plant or on the branch that bears them is a very
important character to observe. In the butter-cup the
flower that terminates the axis of the plant opens first,
then that nearest it. and so on till the flower furthest
from the first has opened. The same order is observ-
able in the chickweed, stich-wort, pink, and sweet-
william, though in these the side-flowers grow on
pedicels that lengthen and over-top that which bears
the one that flowered first. Such inflorescences are
called centrifugal, the order of flowering being from
the central axis outwards ; or definite, because the
axis is terminated by a flower and does not elongate.

In the foxglove, wall-flower, and indeed most other
plants, the order of flowering is the reverse of this ; the

46 SCIENCE PRIMERS. [XL

flower furthest from the axis opening first, and that
terminating the axis last of all. Such are centripetal
inflorescences, also called indefinite, because the axis
goes on elongating after the first flower opens. When
the flowers are crowded this difference of order of
opening is quite as conspicuous. Thus the elder in-
florescence is centrifugal, the daisy and carrot centri-
petal. The teazle is a very rare exception ; in it the
middle flowers, those half-way up the head, open first,
and the order of opening is both upwards and down-
wards from these : this is called a mixed inflorescence.

78. The common sorts of inflorescence are —

(a) The spike, where the flowers are sessile on the
peduncle (plantain). A catkin is a spike that falls
away after flowering (walnut, oak, poplar, birch).

(b) The raceme is a spike with pedicelled flowers
(currant, foxglove, snapdragon, mignonette).

(c) In the head, the flowers are sessile and crowded
in a dense mass (daisy, teazle, scabious, clover).

(d) The panicle is a raceme in which each pedicel
branches again (oat, horse-chesnut, lilac).

(e) In an umbel all the pedicels start from one
point and the flowers reach about the same level;
(flowering rush, onion, cowslip) ; when the pedicels
of the umbel are again umbelled the umbel is called
compound (carrot, parsnip).

(/) In the corymb, the flowers reach the same
height, but their pedicels do not spring from the same
level; (elder, star of Bethlehem, hawthorn.)

79. The leaves of the inflorescence are modifica-
tions of the same organs as occur on the stem, but they
serve a different purpose, being usually protecting
organs to the young flower ; those at the base of or

xii.] BOTANY. 47

on the peduncles are called bracts, those at the base
of or on the pedicels bracteoles ; the bracts at the
base of or around a head or umbel or flower, are often
crowded together, and form an involucre, which may
consist of one whorl of leaves (carrot), or of many
overlapping bracts (daisy, acorn-cup).

XII.— THE FLOWER.

80. The use of the flower is to bring about the
multiplication of the plant by seed.

8 1. The flower consists of one or more series of
organs crowded round the tip of a peduncle or pedicel
(Par. 76), and called floral whorls. These differ
greatly in form, colour, and size ; but ell bear the same
relation to the stem as leaves do, and are modifica-
tions of the leaf-type. All foliar organs are developed
on one plan, but take different shapes and perform
different functions according to the requirements of
the plant.

82. Before describing the individual floral organs,
it will greatly facilitate the student's progress to fami-
liarize him with their number, form, and relative
positions, in flowers which differ very widely from
one another. Beginning from without, the floral
whorls are : —

(a) Calyx, a protective organ ; it forms the first or
outer whorl, is usually green, and its pieces, called
sepals, may be separate (free), or combined into
a cup or tube, wholly or in part only.

(b) Corolla, an attractive organ ; it forms the
second whorl; it is white or coloured (very rarely
green) in order to attract insects to the flower : honey

48 SCIENCE PRIMERS. [xn.

is often exuded at particular points within it. Its
pieces, called petals, may be free or combined into
a cup or tube, or into the form of a bell, a funnel, &c.

(c) Stamens, usually slender organs, form the
third whorl, they consist of a stalk (filament), sur-
mounted by a 2-lobed body, the anther, containing
a fine yellow-powder, the pollen, necessary to per-
fecting seeds. The filaments may be absent or com-
bined into a tube, or into bundles, or be altogether
free, as may the anthers.

(d) The Pistil, or central organ, forms the inner-
most or fourth whorl, and presents many more modi-
fications than any of the preceding. In its simplest
form (pea) it represents a leaf folded down the middle
with its edges united so as to form a hollow vessel
(ovary) ; the tip tapers into a stout or slender body
(style), which terminates in one or more rough or
moist, often swollen nobs or surfaces or points
(stigmas). The style may be absent, when the
stigma is sessile on the ovary.

The pistillar leaf is called a carpel, and its cavity
contains, attached to its inner surface, one or more
minute bodies, destined, after fertilization (by the
. action of the pollen on the stigma), to become
seeds. The pea-pod is one such carpel with several
ovules. The buttercup has many such carpels, each
with one ovule, style, and stigma. When there are
several carpels they may be free (buttercup), or com-
bined by their edges into a one-celled ovary (violet\
or by their sides into an ovary with as many cells
as carpels (lily). In these cases of united carpels the
styles may be free or combined; and when com-
bined, the stigmas may still be free. The number of

XIL] BOTANY. 49

carpels of which a pistil is formed, when these are
combined, may often be assumed from the number
of cells of the ovary, or of styles or of stigmas.

(e) The floral receptacle is the tip of the flower-
stalk which bears the floral organs. The disk is a
thickening of the receptacle between the pistil and
corolla or calyx ; it is often swollen (rue, lime), and
secretes honey ; or it is represented by scales or small
prominences. The stamens may be inserted around
it, or on it, or between it and the ovary.

83. If a flower contains all four floral whorls (Par.
81), it is called complete ; if fewer, incomplete.
The calyx and corolla together form the perianth ;
also when the calyx is undistinguishable from the
corolla, or when either of these is absent, the outer
floral whorl takes the name of perianth.

Of the floral whorls, the calyx is seldom absent, the
corolla less seldom. The stamens and pistil cannot
both be absent, but one may be : in this case the
missing whorl will be found in correspondingly in-
complete flowers borne on the same or some other
individual plant. Very few flowers have fewer than
two sepals or two petals, but many have either no
stamens or no pistil ; and a flower may consist of
a single stamen or a single pistil.

An irregular flower is one in which one or more
of the parts of the calyx or corolla is larger than
another (pea, snap-dragon). A regular flower is one
in which this is not the case, but the members of each
whorl are equal and similar.

A symmetrical flower is a regular one whose
sepals, petals, and stamens are equal in number
or multiples of one another.

50 SCIENCE PRIMERS. [xn.

84. The principal modifications of the flower de-
pend on (a) the absence of one or more of the above
whorls, and the form of those that exist ; (b) on the
members of each being free or combined ; (c) on
the members of one whorl being adherent to those
of the one next outside or inside of it ; (d) on the
position of each whorl upon the receptacle. Of these
modifications, the most obvious is that the ovary is
sometimes placed above the calyx (buttercup, Fig. 22),
and sometimes apparently below it (snowdrop, daffo-
dil, Fig. 37). In the latter case, the appearance is
caused either by the ovary being sunk in the top of
the flower-stalk, and becoming one body with it, or by
the lower part of the calyx adhering to the walls of
the ovary; in either case the corolla, disk, and stamens
are carried up above the level of the ovary, and are
as it were inserted upon it. The rose (Fig. 31) and
apple (Fig. 32) are obvious examples of the ovary
being sunk in the top of the flower- stalk.

85. The flowers enumerated below are now to be
examined, and the pupil taught to name the organs
of each and their uses ; this done, the organs should
be described according to their modifications. In
doing so, attention should first of all be given to the
following points : —

(a) Whether the flower is complete, (Par. 83);
if not, which whorls are absent.

(b) The number of members of each whorl, and
whether they are opposite or alternate with the
members of the whorl outside it.

(c) Whether the members of each whorl are free, or
combined together, and whether they adhere to those
of the whorl outside or inside of them.

XII]

BOTANY.

(d) Whether the flower is regular or irregular
(Par. 83).

(e) Whether the flowers are bisexual, having both
stamens and pistil (buttercup), or unisexual, having
one only of these; and if the latter, whether the
flowers that bear the stamens are monoecious, that
is, on the same individual with those that bear the
pistil (oak, nut), or diccecious, that is, on another
individual (willow, common nettle).

(/) Whether the calyx is above the level of the
ovary or below it.

A. — Complete flowers with inferior perianth (the
calyx and corolla being below the ovary).

Buttercup (Fig. 22). — Flower regular. Calyx of 5
free sepals. Corolla of 5 free petals alternate with the

FIG. 22. — Vertical section of Buttercup flower, enlarged.

sepals. Stamens many, seated on the receptacle.
Pistil of many free carpels.

SCIENCE PRIMERS.

[XII.

Bramble (Fig. 23). — Flower regular. Calyx of 5
sepals combined at the base. Corolla of 5 free petals.
Stamens many, seated on the calyx. Pistil of many
free carpels. (Note the different insertion of petals
and stamens of buttercup and bramble.)

FIG, 23. — Vertical section of Bramble flower, enlarged.

Wallflower (Fig. 24, 25). — Flower rather irregular.
Calyx of 4 free sepals, two inserted lower down than

FIG. 24.— Vertical section of Wall-flower,
enlarged.

FIG. 25. — Stamens of Wall
flower, enlarged.

XIL] BOTANY. 53

the others. Corolla of 4 free petals. Stamens 6, two
shorter than the others, and placed opposite the lower
sepals. Pistil of 2 carpels combined into a 2-celled
ovary with a very short style and notched stigma.

Pink. — Flower regular, with many bracts. Calyx
of 5 sepals combined into a 5-cleft tube. Corolla
of 5 free petals alternate with the sepals. Stamens
TO, five alternate with and five opposite to the petals.
Pistil of 2 combined carpels forming a i -celled ovary
with 2 styles.

FIG. 26. — Vertical section of flower of Mallow, enlarged.

Mallow (Fig. 26). — Flower regular, with 3 bracts.
Calyx of 5 free sepals. Petals 5, alternate with the
sepals, combined below. Stamens very many, fila-
ments combined into a tube which adheres at the
base to the petals. Pistil of many carpels combined,
with many combined styles with free stigmas.

54

SCIENCE PRIMERS.

[XII.

Pea (Fig. 27). — Flower irregular. Calyx of 5 com-
bined sepals. Corolla of 5 very unequal petals of
which the two innermost are combined. Stamens 10,
9 united and i free. Pistil of i carpel, with i style
and stigma.

FIG. 27. — Section of flower of Pea, enlarged

FIG 28. — Vertical section of flower of China
Primrose, enlarged.

FIG. 29. —Transverse sec-
tion of ovary, enlarged.

xii.] BOTANY. 55

Primrose (Fig. 28, 29). — Flower regular. Calyx
of 5 combined sepals. Corolla of 5 petals combined
into a tube below. Stamens 5, opposite the petals,
their filaments combined with these. Pistil with a
i -celled ovary having i style and stigma.

Deadnettle (Fig. 30). — Flower irregular. Sepals
5, combined into a cup. Corolla of 5 petals com-

FIG. 30. — Vertical section of Dead-nettle flower, enlarged.

bined into a tube with two lips ; lobes alternate with
the sepals. Stamens 4, 2 longer than the others.
Pistil of 2 carpels forming a 4-celled ovary with i
style and cleft stigma.

B. — Complete flowers with superior perianth.

Rose (Fig. 31).— Flower regular. Calyx of 5
sepals. Corolla of 5 free petals, alternate with the
sepals. Stamens many, seated on the calyx. Pistil

SCIENCE PRIMERS.

[XII.

of many separate carpels sunk in the hollowed top
of the pedicel.

FIG. 31. — Vertical section of Rose, enlarged.

Apple (Fig. 32). — Flower regular. Calyx of 5
sepals. Corolla of 5 free petals, alternate with the
sepals. Stamens many, seated on the calyx. Pistil
of 5 combined carpels, each with a style.

FIG. 32. — Vertical section of Apple flower, enlarged.

Gooseberry. — Flower regular. Calyx of 5 sepals.
Corolla of 5 free petals. Stamens 5, alternate with the
petals, seated on the calyx. Pistil of 2 carpels com-
bined, forming a i -celled ovary with 2 styles.

XII.]

BOTANY.

57

Campanula. — Flower regular. Calyx of 5 sepals.
Corolla of 5 combined petals alternate with the sepals.
Stamens 5, alternate with the petals, seated on the top
of the ovary. Pistil of 3 or 5 carpels combined into
a 3- or 5-celled ovary, with i style and 3 or 5 stigmas.

Elder. — Flower regular. Calyx of 5 sepals.
Corolla of 5 combined petals alternate with the sepals.
Stamens 5, seated on the corolla and alternate with
the petals. Pistil of 2 combined carpels with 2 cells
and i style and stigma.

Honeysuckle. — Flower irregular. Calyx with 5
minute teeth. Corolla of 5 petals combined in a tube.
Stamens 5 seated on the corolla, alternate with the
petals. Pistil of 3 combined carpels with 3 cells and
i style and stigma.

Daisy (Fig. 33, 34). — Flower of 2 forms in a
compact head surrounded by green bracts. Outer

FIG. 33. — Vertical section of head of FIG. 34.— Inner flower from
Daisy, enlarged.

FIG. 34. — Inner flower fron
head of Daisy, enlarged.

flowers unisexual, irregular, white. Corolla white, of
5 petals combined into a narrow long ray. Stamens o.

58 SCIENCE PRIMERS. [xii.

Pistil with i cell i style and 2 stigmas. Inner flowers
bisexual, regular, of 4 or 5 petals combined into a
yellow tubular 4-5 cleft corolla. Stamens 4 to 5,
seated on the corolla, anthers combined. Pistil as
in the outer flowers.

C. — Incomplete flowers, having an inferior perianth.

Dock. — Flower regular. Perianth of 6 nearly free
pieces. Stamens 6, seated at the base of the perianth,
alternate with the perianth pieces. Pistil of 3 com-
bined carpels with i cell and 3 styles.

Daphne (Fig. 35). — Flower regular. Perianth of
4 combined pieces. Stamens 8, seated on the
perianth, 4 upper opposite, 4 lower alternate with the
perianth pieces. Pistil of one i -celled carpel with i
style and stigma.

FIG. 35.— Vertical section of Daphne Hower, enlarged.

Tulip (Fig. 36). — Flower regular. Perianth of 6
free pieces. Stamens 6, opposite the pieces of the
perianth. Pistil of 3 carpels combined into a 3-celled
ovary with i style and a 3-lobed stigma.

XII.]

BOTANY.

59

FIG. 36. — Vertical section of Tulip flower.

D. — Incomplete flowers having a superior perianth.

Daffodil (Fig. 37). — Flower regular. Perianth of
6 pieces with a raised crown. Stamens 6, seated on

FIG. 37. -Vertical section of Daffodil flower.

6o

SCIENCE PRIMERS.

[XII.

the base of the perianth opposite its pieces. Pistil of 3
combined carpels with 3 cells and i style and stigma.
Orchis (Fig. 43).— Flower irregular. Perianth
irregular of 6 pieces. Stamen i, combined with the
style. Pistil of 3 carpels combined into a i-celled
ovary.

E. — Flowers without an obvious -perianth.

Willow (Fig. 38, 39). — Flowers in catkins (78).
Catkins of two kinds on different plants, both formed
of overlapping scales ; those of one kind of catkin
overlying each one or more stamens ; those of the other
catkin overlying each a single pistil. Pistil of 2 carpels
combined into a i -celled ovary with 2 styles.

FIG. 38.— Male flower of Willow,
enlarged.

FIG. 39.— Female flower of Willow,
enlarged.

Wheat (Fig. 40). — Flowers in spikelets consisting
of 2 minute scales (the perianth), 3 stamens and i

XII.]

BOTANY.

61

pistil, the whole inclosed in two sets of green bracts.
Pistil with i cell and 2 styles.

FIG. 40. — Spikelet of Wheat, enlarged.

86. It has been already stated that the above organs
of a flower are all formed on the plan of leaves, but
modified for different purposes. The best evidence of
this is afforded by, (a) the calycanthus, which shows
the transition from leaves to bracts, from bracts
to sepals, and from sepals to petals ; by (<£), the white
water lily, which shows the transition from sepals to
petals, and from petals to stamens ; (c\ the garden rose,
and most double flowers, which show the transition
from petals to stamens ; (d), the double tulip, which
shows the transition from stamens to pistil ; (<?), the

62 SCIENCE PRIMERS. [xin.

double cherry, in which the carpels appear as green
leaves.

87. The number of sepals, petals, and stamens is
in Dicotyledonous plants, most frequently 4 to 5 each,
or a multiple of that number ; whereas 3 or a multiple
of that number prevails in Monocotyledons; which
is the fourth means of distinguishing plants of this
class (see Pars. 39, 53, 60, 73).

XIII.— THE CALYX.

SEPALS.

88. The calyx is formed of a whorl of free or com-
bined organs called sepals. It is usually green and
leaf-like in texture, and it often persists in the fruit.
Its use is to protect the parts of the flower within it.

89. Although the outermost of the floral whorls, the
calyx is sometimes placed at a higher level than the
ovary. This is because either the ovary is sunk in the
swollen top of the peduncle (rose, Fig. 31); or because
the surface of the sepals adheres more or less to the
sides of the ovary, their free parts spreading out above
it. Hence the employment of the terms calyx superior
and calyx inferior, which are equivalent respectively
to ovary inferior and ovary superior (Par. 84 d ).

90. The sepals of the calyx may be free from one
another, when the calyx is polysepalous (butter-cup,
Fig. 22) ; or combined, when it is monosepalous (prim-
rose, Fig. 28).

91. The most curious form of calyx that commonly
occurs is that of the dandelion, groundsel, thistle,

XIV.]

BOTANY.

and other plants with their flowers in heads (Par. 78*:).
Here the ovary is inferior, and the superior calyx is
represented by a tuft, of fine hairs, called a pappus.

FIG. 41. — Dandelion fruit with
pappus, enlarged.

FIG. 42. — Thistle fruit with pappus.

The valerian has a similar calyx. In these plants the
feathery calyx assists in the dispersion of the fruit.
The calyx may take some of the irregular shapes to
be described under the Corolla.

XIV,— THE COROLLA.
PETALS.

92. The corolla is formed of a whorl of free or
combined organs called petals. It is usually coloured
and thin, and much larger than the calyx ; it is often
scented, and soon fades, rarely persisting in the fruit
(which it does in the campanula). Its use is to attract
insects and birds to flowers for the purpose of fertilizing

64 SCIENCE PRIMERS. [xiv.

them (Sect. XX), and it also often protects the parts
of the flower within it. The many colours of flowers,
their various shapes and scents, and their honey, are
so many baits, for insects especially.

93. The corolla is inserted on the receptacle (Par.
82 e) in the butter-cup; on the calyx in the apple
(Fig. 32) and rose (Fig. 31); in flowers with a superior
calyx (campanula), apparently on the top of the ovary,
but really on the calyx or peduncle, where these
become free from the ovary.

94. The petals of the corolla may be free from one
another, when the corolla is polypetalous (buttercup,
Fig. 22) ; or combined, when it is monopetalous
(primrose, Fig. 29).

FIG. 43. — Spotted orchis-flower, enlarged.

95. The so-called irregularity or regularity of flowers
(Par. 83) depends mainly upon the form of the corolla,
and has reference to the visits of insects, &c. for the

xiv.] BOTANY. 65

purpose of fertilization. Of these irregular forms the
most common monopetalous one is the mask-like or
personate (snap-dragon, dead-nettle, Fig. 30); and the
most common polypetalous one is the butterfly-shaped
or papilionaceous (clover, pea, Fig. 27). The latter
is so characteristic of a very large family of plants
(pea family) that names have been given to its five
petals ; the upper being called the standard, the two
side ones wings, and two within them, which are
often combined by their lower margins, form the keel.
If the visits of bees to irregular flowers are watched,
it will be seen, in very many cases, that the form
of the corolla is singularly adapted to facilitate the
insect entering it in order to obtain honey for itself,
when it also carries away pollen from the stamens
(Par. 123).

96. The commonest regular monopetalous corollas
are the bell-shaped (campanula), funnel-shaped (con-
volvulus), salver-shaped (primrose), and wheel-shaped
(pimpernel) . In these, as in the regular polypetalous
corollas (apple, Fig. 32, buttercup, Fig. 22), there is
little or no relation between the form of the flowers
and those of the insects that visit them. In some
instances however of regular monopetalous flowers,,
there is a special adaptation of the organs of the
flower to those of the insect, as where the corolla has
a long tube and the insect a long proboscis ; the bee
and primrose is an example (Par. 122).

97. Petals are formed of a thin plate of cellular tissue
traversed by vascular bundles (Par. 9). Their colour-
ing follows certain rules. The corollas of few or no
plants present all the primary colours, and white alone
is found in all families of plants with coloured corollas.

66 SCIENCE PRIMERS. [xv.

White and various shades of yellow and red are found
in roses, tulips, and rhododendrons, but never blue.
Blue, yellow and white are found in gentians, but
very rarely red. Anemones are amongst the few plants
in the different kinds of which red, yellow, blue, and
white are found. Night-flowering plants have usually
large, white, very strong-scented corollas, on purpose
to attract moths. Certain lurid red or purple flowers
both look and smell like putrid meat, and hence
attract flies, which lay their eggs on them and fly away
with the pollen.

98. Honey when secreted on the corolla is usually
at its very base (honeysuckle, crown-imperial), and to
reach it the insect has to disturb or brush against
the stamens, and hence carry away pollen. In the
grass of Parnassus, the honey is secreted in the tips
of the branches of an elegant comb-like scale opposite
each petal. The glands that secrete the honey are
called nectaries.

FIG. 44. — Honey glands of, «, buttercup ; by barberry ; both enlarged.

XV.— THE DISK.

99. Usually at the base of the stamens and around
that of the ovary, there is a thickened ring of cellular
tissue, or a whorl of swellings, scales, or glands. It
very often secretes honey when the corolla does not,

XVI.]

BOTANY.

67

and is a part of the floral receptacle (Par. 82^). In
the buttercup (Fig. 22) there is no disk; in the bramble
(Fig. 23) it forms a thickened shining lining of the
base of the calyx ; in the orange (Fig. 45 a) and mig-
nonette (Fig. 45 £) it forms a distinct cushion; in the

FIG. 45.— Disks of, a, orange ; b, mignonette : both enlarged.

wallflower it appears as two moist honeyed glands
at the base of the short stamens ; and in the carrot
and similar flowers it crowns the ovary.

XVI.— AESTIVATION.

100. As the folding together of the leaves in bud is
called vernation (Par. 69), so that of the floral organs
is called aestivation. In this folding that of the sepals
never interferes with that of the petals, and these
often follow quite different plans. These plans are
constant throughout the flowers of any one kind of
plant, and the same plan prevails through many allied
plants ; in other words, aestivation is a guide to the
detection of relationships amongst plants.

1 01. There are four principal plans of estivation.
T. Imbricate, when one or more pieces are outside

68 SCIENCE PRIMERS. [xvn.

the others, which others may all overlap by one margin,
or one of them may be inside all the others (petals of
apple). 2. Twisted, when each overlaps by one
margin the contiguous margin of that next to it
(corolla of periwinkle, convolvulus). 3. Valvate,
when they meet by their edges without overlapping
(calyx of mallow). 4. Open, when they grow quite
apart, neither overlapping nor touching (petals of
mignonette).

FIG. 46. — ^Estivations : a, imbricate ; t>, twisted ; c, valvate, with the edges
turned outward.

102. The stamens usually grow straight from the
first, but are sometimes curved or rolled inwards
(myrtle and nettle), or backwards (kalmia).

XVII.— THE STAMEN.
ANTHER, POLLEN, FILAMENT.

103. The stamen consists essentially of the anther,
a 2-lobed, 2-celled organ filled with granules (the
pollen); its lobes are placed right and left to the
axis of the flower. The anther may or may not
have a stalk (filament), which contains a vascular
bundle (Par. 9) that terminates between the anther-
lobes. The use of the stamen is to form, contain, and
discharge the pollen.

XVIL] BOTANY. 69

104. Stamens are variously inserted, but always
within the calyx and corolla and outside the pistil, if
these be present. They vary in number, and may be
in one or more series ; when equal in number to the
petals or divisions of the perianth, they usually alter-
nate with these in Dicotyledons, but are opposite to
them in Monocotyledons ; when twice as many they
are alternate and opposite. They are inserted on the
receptacle in the buttercup (Fig. 22), on the calyx in
the bramble (Fig. 23), on the disk in the lime, on the
corolla in the primrose (Fig. 29), and are combined
with the pistil in the orchis (Fig. 43). The filaments
are free in most plants; more or less combined in
the mallow (Fig. 26) ; combined by bundles in St.
John's wort ; nine are united together and one is free

FIG. 47. — Stamens of pea, nine combined and one free ; enlarged.

in the pea (Fig. 47). The anthers are usually free,
but combined in the thistle and daisy, the filaments
being free.

105. The anther in its early state is a cellular
2-lobed body, with longitudinal rows of special cells
in the centre of each lobe. The contents of each of
these special cells (called mother-cells) divide into four,
which form as many pollen grains. These pollen grains
acquire first one and then a second cellulose- (Par. n)
coat, and finally escape from the mother-cell and lie
loose in the cavity of the anther.

SCIENCE PRIMERS.

[xvn.

1 06. When fully formed the anther-cells open to
allow the pollen to escape, in most plants by longi-
tudinal slits on the face (towards the pistil) ; but in
some by lateral slits (buttercup), or dorsal ones (iris).
In the heath order the anthers open by terminal pores
(Fig. 48 b\ which in the bilberry (Fig. 48 a) are at the
end of long tubes. In the barberry (Fig. 48^:) they open

Bilberry.

Heath.

Barberry.

Mistletoe.

FIG. 48.— Stamens of. a, bilberry; b, heath ; c, barberry; d, mistletoe: all
much enlarged.

by oblong lids that fall away ; and in the mistletoe
(Fig. 48^) by many holes, each of which is a pocket
full of pollen.

FIG 49. —Transition from stamen a, to petal />, and to sepal c, in double rose.

XVII.]

BOTANY.

107. The relation of the stamen to the leaf is not
so clear as are those of the sepals, petals, and carpels;
nevertheless the transition from petal to stamen is
obvious in the white waterlily, and in manv double
flowers, as the rose (Fig. 49).

FIG. 50. — a, pollen grains of orange ; b, pollen grains of buttercup upon the
stigma with their tubes descending to the ovule ; both very much
enlarged.

108. The pollen grains are usually globose, or ellip-
soid, or rounded with obtuse angles ; they are generally
free, but sometimes escape from the mother-cell con-
nected in fours (rhododendron). In orchis they escape
as club-shaped masses (Fig. 57). The surface of the
granules is smooth, sculptured, or prickly, and this and
their size and shape are wonderfully constant in each
kind of plant, and through many allied plants.

A pollen-grain consists of two cellulose coats and
fluid protoplasmic contents. When placed on the
stigma (Par. 112), one or more tubes formed of the
inner cellulose coat are pushed through slits or holes
in the outer, and descend through the stigma and

SCIENCE PRIMERS.

[XVIII.

style to the cavity of the ovary, finally conveying
protoplasmic fluid from the pollen to the ovule.

FIG. 51.— Pollen grains of, a, evening primrose ; and b, cherry ; both emitting
pollen tubes— very greatly enlarged.

XVIII.— THE PISTIL.

OVARY, STYLE, STIGMA.

109. The pistil is by far the most complicated organ
of the flower, and consists of one or more carpellary
leaves (Par. 82 d). If it is composed of many such
leaves, these may be so combined as to form a one-
or many- celled ovary. Its use is to produce within
its cavity ovules, destined to become seeds, and to
provide means for conducting the contents of the
pollen to the ovules.

no. The ovules are generally produced on the
edges of the carpellary leaf; which presents a spongy
thickening called the placenta, to which the ovules
are attached by a short or long cord or stalk called
the funicle.

The position of the placenta depends on the
composition of the pistil; if the latter is formed

XVIIL] BOTANY. 73

of one carpel (pea, Fig. 27) the placenta will be on
the walls of the cavity of the ovary (parietal); so also
if two or more carpels are united by their edges only
(Fig. 53), the ovules will still be parietal; but if two
or more carpels are closed by the infolding of the
edges of the carpel! ary leaves as far as the axis of the
pistil, and are combined by their sides into one,
the ovules will be on the axis of the pistil or on
placentas projecting from it (Figs. 36, 37, 52).

FIG. 52.— Axile ovules. FIG. 53.— Parietal ovules.

in. The style consists of a column of cellular
tissue continuous with the midrib and margins of the
carpellary leaf or leaves, enclosing a core of looser
cellular tissue amongst which the pollen tubes (Par.
1 08) descend to the ovary.

112. The stigma occupies the top, or the sides of
the top of the style ; or of the ovary if there is no
style, and is not covered with epidermis (Par. 6),
which would obstruct the descent of the pollen tubes.
It is frequently formed either of short loose cells
which exude a viscid fluid that holds the pollen grains,
and hastens the protrusion of their tubes ; or of long
cells, forming tufts of hair, amongst which the pollen-
grains become entangled.

74

SCIENCE PRIMERS.

[xix.

XIX.— THE OVULE.

113. The ovule is a minute body enclosed in the
ovary, and destined, after being fertilized by the pollen,
to become a seed, and to contain an embryo or
plantlet. There may be one, few, or many ovules in
an ovary; and if there are two or more, all, or a
few, or one only, of these may be fertilized and
become a seed.

114. In its earliest stage the ovule consists of a
nucleus, which is a most minute swelling of cellular
tissue formed on the placenta (Par. no). Next a ring
of cellular tissue grows up around the base of the
nucleus and all but envelops it, leaving a canal or hole
(micropyle). Often a second ring forms at the base
of the first, and is similarly developed into an outer
covering. A vascular bundle (Par. 9) runs from the
edge of the carpellary leaf through the placenta into

FIG. 54-— Growth of ovule of celandine : a, nucleus ; b, first formed covering ;
c, second covering— very greatly enlarged.

the ovule, reaching the base of the nucleus, and is
concerned in its nutrition and in that of the seed.

115. The ovule may be straight, or it may grow
obliquely, or it may as it were turn round on itself by
the greater growth of one side, so as to become com-

XIX.]

BOTANY.

75

pletely inverted, when the micropyle, instead of being
distant from the placenta, is brought into proximity to
it, and the base of the nucleus is at the top of the
ovule. In this last case the vascular bundles from the
placenta run up the side of the ovule to the base of
the nucleus.

1 1 6. In the axis of the nucleus, a cavity lined with
a delicate membrane (the embryo sac) containing
protoplasm, appears. Within this sac again near its
top a dark spot is seen (germinal vesicle), which,
after the application of the tip of the pollen tube to

FIG. 55.— Longitudinal section of ovule of heartsease : a, placenta; Z>, outer
coat ; c, inner coat ; d, nucleus ; e, embryo sac, with the germinal vesicle
at its small end ; ./", micropyle ; g, end of pollen-tube—very much enlarged.

the nucleus, acquires a cellulose coat, and becomes a
cell. This cell, by division (Par. 13), gives origin
to a filament, from the end of which the embryo Is
developed.

76 SCIENCE PRIMERS, [xx.

XX. -FERTILIZATION.

117. Though stamens and pistil frequently occur in
the same flower, it does not follow that the pistil of
such a flower is fertilized by its own stamens. On
the contrary, it has been proved by many careful
observations and experiments that nature has pro-
vided that pistils should be fertilized by pollen from
other flowers, or from the flowers of other plants.
Hence some plants bear stamens and pistils on
separate flowers of the same individual (oak, hazel);
others have stamens and pistils on different individuals
(willow) ; in others again, when stamens and pistil
occur in the same flower, they do not become mature
at the same time; and in still others, when stamens
and pistil do occur in the same flower and are mature
at the same time, they are so placed in reference to
one another or to the corolla &c., that the pollen
cannot reach the pistil.

1 1 8. It has also been proved, that, as a rule, a pistil
fertilized by the pollen of another flower, or that of
another individual of its own kind, produces more and
larger seeds which grow into stronger plants, than if
it had been fertilized by the pollen of its own flower.

119. These and many other observations tend to
prove that the elaborate structures, colours, scents,
honeyed secretions, and other attractions of the corolla,
stamens and pistil, and their adjustments to one
another and to the forms and habits of insects, are all
intended to prevent flowers from being fertilized by
their own pollen, and to facilitate their being fertilized

XX.]

BOTANY.

77

by pollen brought from other flowers. This operation
is called cross-fertilization.

120. In respect of fertilization flowering plants may
be roughly classed under two heads, according as
the pollen is carried to the pistil by the wind or by
insects.

Wind-fertilized plants have, as a rule, stamens and
pistil in different flowers or individuals. Their flowers
are not bright-coloured, are scentless, and have no
sugary secretions, and their stigmas are covered with
hairs that retain the pollen ; in some the anthers hang
out of the flower (plantain, poplar, willow, oak); their
pollen is abundant, dry, and powdery (birch, alder,
pine).

121. Insect-fertilized plants, on the other hand, pre-
sent innumerable contrivances to ensure the fertiliza-
tion of the pistil by pollen from another flower or
plant, of which the following examples must suffice-

FIG. 56. — Vertical section of corolla of, a, long-styled, and b, short-styled
primrose.

122. The primrose has two sorts of flowers, which
never occur on the same plant ; one has the stamens

78 SCIENCE PRIMERS. [xx.

far down the corolla tube, and the stigma high up at
its mouth, the other has stamens high up the tube and
the stigma far down; both have honey at the very
bottom of the corolla tube. When a bee visits a
short-styled flower, it thrusts its proboscis to the
bottom and, withdrawing it, brings away some pollen
at its base. If it then visits another short-styled
flower it cannot fertilize it, and only takes more pollen
away ; but if it visits a long-styled flower it must de-
posit pollen on its stigma, that being at the mouth of
the corolla. If, on the other hand, the bee first visits
a long-styled form of primrose the operation is reversed,
it will then carry away pollen upon the tip of its
proboscis and deposit this on the stigma of the next
short-styled flower it visits.

123. In the common orchis the anther is placed
above the stigma, which is a hollow viscid cavity in
front of the flower, at the base of the lip, and the lip
is produced into a long tube full of honey. A bee
seeking honey thrusts its head against the anther, and
in so doing detaches one or both of the two sticky
glands to which two club-shaped masses of pollen are
attached ; these it carries away on its forehead, in
an erect position. So long as the pollen masses
are erect on the bee's head these do not reach the
stigma of any other flower that it visits ; gradually,
however, as the sticky gland contracts, the pollen
masses incline forward and assume a horizontal
position, in which they must touch the stigma of
the next flower the bee visits, when the greater
stickiness of the stigma detaches some or all the pol-
len from the bee's head and fertilizes the flower.
Further, in some cases it takes so long for the pollen

XX.]

BOTANY.

79

to assume the horizontal position, that by the time
this has taken place the bee has visited all the flowers
of the plant from which it took the pollen, and has
gone to another plant.

FIG. 57.— a, section of flower of orchis, shewing a bee standing upon the
lip with its head touching the sticky gland to which the pollen masses
are attached ; b, bee's head with the pollen masses erect, as removed ; c,
the same with the pollen masses after they have moved forwards :
all enlarged.

124. Birds with long slender bills, as humming-
birds, and also great moths, thus fertilize long-tubed
flowers ; in all which and many other cases the adjust-
ment of the parts of the flower to the form and habits
of the insect or bird, and of these to the flower, is so
accurate, that it is in vain to speculate whether the
plant was adapted to feed the animal, or the animal
adapted to fertilize the plant.

So SCIENCE PRIMERS. [xxi.

XXI.— THE FRUIT.
PERICARP, SEED.

125. The fruit consists of a covering (seed-vessel,
or pericarp) containing one or more ripe seeds, The
term should strictly apply to the result of the fertiliza-
tion of one pistil," but it is extended to crowded
masses^ of fruits belonging to several flowers on one
peduncle or branch (mulberry Fig. 58, pine-cone).
These are called aggregate fruits, or infructescences,
just as the aggregates of flowers are called inflor-
escences (Par. 75). Further, various organs of the
flower, or inflorescence, when retained on the fruit,
are considered parts of the fruit; as the acorn-cup,
which is formed of scale-like bracts (Par. 79); the flesh
of the apple, hip, and pear, which are all formed of
the swollen peduncle ; the strawberry (Fig. 64), which
consists of a fleshy receptacle covered with ripe
carpels ; and the fig (Fig. 59), which is a hollow fleshy
peduncle containing many ripe carpels.

126. The study of the fruit is more complicated than
that of any other organ of the plant, because : i. of
its composition, which can only be made out by an
examination of the pistil (Sect. XVIII.) ; 2. because
many parts visible in the pistil are often suppressed or
masked in the fruit ; 3. because the seed is not always
as distinguishable from the pericarp as the ovule
always is from the ovary ; 4. because accessory organs
are so often attached to it or envelope it; 5. because
carpels that are free in the pistil may become com-
bined in the fruit; 6. because the placentas (Par. no)

XXL] BOTANY. 81

sometimes grow out and form additional partitions in
the cavity of the fruit.

127. The simplest classification of fruits is into :—
r. pods; these are dry, and their pericarp splits open
along denned lines, or parts into separate pieces called
valves (pea Fig. 61, wallflower Fig. 67); such are
dehiscent fruits, their seeds fall out of the pericarp
after it splits open. 2. Dry fruits that do not open by
valves and are hence called indehiscent ; the seeds
of such do not fall out, but germinate within the peri-
carp, the embryo either throwing off the pericarp
(maple), or its cotyledons remaining within it (acorn) ;
of these there are two kinds, the nut, which is large
and hard, and the achene, which is small and usually
has a thin pericarp. 3. Indehiscent fleshy fruits, that
either rot on the ground and thus set the seeds free,
or are eaten by birds, which digest the flesh and reject
the seeds (apple, holly, mistletoe, gooseberry). The
chief kinds of these are the berry, which has a soft
pericarp, and the drupe, of which the inner walls of
the pericarp are hard and bony, or stony.

128. The above classification teaches nothing of the
real nature of the fruit ; the following does, and in-
cludes the chief kinds accessible to the student, who
by learning all will obtain a better knowledge of fruits
than he could by any other means. He should be
careful to observe whether the fruit is inferior or
superior (Par. 84 d], and further, in the cases of fruits
that are composed of many combined dehiscent carpels,
he should observe whether they split between the
carpels (septicidal), or down their backs (ioculicidal) ;
or by the carpels parting from their axes (septi-
fragal).

82

SCIENCE PRIMERS.

[xxi.

In the following enumeration the character of the
seed is added to avoid subsequent repetition.

A. — Aggregate fruits or Infructescences (Par. 125).

Mulberry (Fig. 58). — A head of fruits, each con-
sisting of a dry i-seeded little indehiscent nut, inclosed
in four juicy perianth pieces.

FIG. 58. — Aggregate fruit of
mulberry.

FIG. 59. — <7, fruit of fig cut vertically ;
by male, and c, female flowers ;
both much enlarged.

Fig (Fig. 59). — A hollowed-out fleshy peduncle,
with bracts at the top, containing innumerable fruits,
each consisting of a little i-seeded indehiscent achene,
together with the withered remains of a perianth.

Pine-cone. — A series of woody scales, each with
two seeds at its base (here there is no pericarp, see
Par. 139).

XXL] BOTANY. 83

B. — Simple fruits formed by the pistil of one flower,
(a) Indehis cent fruits of one carpel.

(i.) Plum, Cherry. — Fruit (a drupe) superior;
pericarp of an outer very fleshy, and inner stony coat.
Seed solitary, without albumen.

(2.) Wheat. (Fig. 12) — Fruit (an achene) superior;
pericarp very thin, adhering so closely to the solitary
seed that it cannot be separated. Seed albuminous.
— In oats and barley the fruit is of the same struc-
ture, but inclosed in the hardened bracts (chaff).

(3.) Nettle (Fig. 60). — Fruit (an achene) minute,
superior, flattened, dry, thin. Seed solitary, without
albumen.

FIG. 60. — a, section of fruit of nettle much enlarged ; b, section of sead of
the same, showing the embryo, still more enlarged.

(4.) Barberry. — Fruit (a berry) superior ; pericarp
fleshy. Seeds i or 2, basal, albuminous.

Thistle (Fig. 42). — Fruit (an achene) crowned with
a calyx formed of a tuft of silky hairs (pappus). Seed
i, basal, erect, without albumen. — In the dandelion
(Fig. 41) the top of the fruit is drawn out into a long
beak and crowned with a similar pappus. In the
daisy the top of the fruit is obtuse and there is no
pappus.

84

SCIENCE PRIMERS.

[xxi.

(b) Dehiscent fruits of one carpel (pods).

(5.) Pea (Fig. 61), Bean. — Fruit superior, divid-
ing into 2 valves, with inner and outer line of de-
hiscence. Seeds many, without albumen, attached to

FIG. 61. — Fruit of pea splitting into two valves.

the line of dehiscence which is nearest to the free
stamen (Fig. 47).

(6.) Willow. — Fruit superior, dividing into 2
valves. Seeds few, without albumen, basal, with long
hairs at their bases.

(c) I ndehiscent fruits of several free carpels.

Buttercup (Fig. 62).- Carpels many, dry (ache-
nes), seated on a dry elevated receptacle. Seeds
solitary in each achene, albuminous.

FIG. 62. — <7, fruit of buttercup, cut open showing the seed ; b, seed of the
same cut open showing the small embryo within the small albumen ;
both much enlarged.

xxii.] BOTANY. 85

Bramble (Fig. 62), Raspberry. — Carpels many,
fleshy (drupes), seated on a dry elevated receptacle.
Seeds solitary, without albumen.

FIG. 63. — Fruit of bramble with stamen and calyx beneath it.

Strawberry (Fig. 64). — Carpels many, dry (ache-
nes), seated on a fleshy elevated receptacle. Seeds
solitary, without albumen.

FIG. 64.— Fruit of strawberry with calyx and bracts beneath it.

Rose (Fig. 31). — Carpels few or many, dry (ache-
nes), seated within the hollowed- out fleshy top of the
peduncle. Seeds solitary, without albumen.

(d) Indehi scent fruits of several combined carpels.

Ash. — Fruit superior, dry, winged (a winged
achene commonly called a key), of 2 combined
carpels, i- celled, each cell i-seeded (one cell is
sometimes suppressed). Seeds solitary, albuminous.
— The maple fruit is of the same nature, but each

86 SCIENCE PRIMERS. [xxi.

carpel has a wing, and the two separate when ripe ;
they do not, however, open so as to let the seed
fail out.

Mallow (Fig. 65). — Fruit superior, a whorl of
many i -seeded carpels (achenes), combined by their
faces. Seeds solitary, albuminous.

FIG. 65. — Fruit of mallow surrounded with the calyx, enlarged.

Deadnettle. — Fruit superior, of 4 dry achenes,
each i-seeded. Seeds albuminous.

Holly. — Fruit (a drupe) superior, fleshy, of 4 com-
bined carpels, with four, i-celled, i -seeded stones.
Seeds albuminous.

Olive. — Fruit (a drupe) superior, fleshy, of 2 car-
pels, forming a single 2-celled stone ; cells i-seeded.
Seeds albuminous.

Potato. — Fruit (a berry) superior, of 2 fleshy
carpels, 2-celled, with many seeds in each cell. Seeds
albuminous.

Apple (Fig. 66). — Fruit 5-celled, of 5 carpels
enveloped in the fleshy swollen top of the peduncle,
each with a horny inner coat, and i or 2 seeds. Seeds

xxi.] BOTANY. 87

without albumen. — {This, the quince, pear, &c., are
called pomes.)

FIG. 66.— Fruit of apple cut across.

Gooseberry, Currant. — Fruit (a berry) inferior,
of 2 fleshy carpels, T -celled, with two placentas, and
several seeds immersed in pulp. Seeds albuminous.

Carrot, Parsnip. — Fruit inferior, of 2 combined
dry carpels (achenes) that finally separate, each i-
seeded. Seed albuminous.

Acorn. — Fruit (a nut) inferior, of 3 combined
carpels, contained in a cup-shaped involucre (Par.
79); of these carpels one alone ripens, the others may
be found as minute cavities at the top of the nut.
Seed solitary, without albumen. — In the beech,
the fruit is of the same structure, but three fruits
are together included in a woody, 4-valved in-
volucre, and each nut is 3-angled. — The sweet chestnut
has the same structure as the beech. (The horse-
chestnut is altogether different, see below.) — In the
hazlenut also the fruit is of the same structure,
but the pericarp is stony and the involucre green and
leathery.

(e) Dehiscent fruits of several combined carpels.

Horse-Chestnut. — Fruit superior, of 3 carpels,
combined into a globose, leathery, prickly, 3-celled

88 SCIENCE PRIMERS. [xxi.

pod, opening to the base by 3 valves. Seeds one in
each cell, without albumen ; cotyledons soldered
together.

Primrose, Cowslip.— Fruit (a pod) superior, dry,
of 5 carpels combined into a i-celled pod, opening at
the top by 5 valves. Seeds many, albuminous.

Violet (Fig. 53). — Fruit superior, dry, of 3 carpels,
forming a i-celled, 3-valved pod. Seeds many, al-
buminous.

Wallflower (Fig. 67). — Fruit superior, dry, of 2
carpels, forming a 2-celled pod, splitting to the base
into 2 valves, which fall away from a framework.
Seeds many, without albumen.

FIG. 67. — Pod of wallflower with one valve coming off.

Poppy. — Fruit superior, dry, of many carpels,
forming a i-celled pod, opening by small persistent
valves under the stigma. Seeds many, albuminous.

Heath. — Fruit superior, dry, of 5 carpels, forming
a 5-celled pod, the cells of which split longitudinally
down the back. Seeds many, albuminous.

XXL] BOTANY. 89

Rhododendron. — Similar to Heath, but the
carpels separate from one another and from the central
axis, and split longitudinally down the front (next the
axis).

Iris, Crocus. — Fruit inferior, of 3 carpels, forming
a 3-celled pod, the cells of which split longitudinally
down the back. Seeds many, albuminous.

Orchis. — Fruit inferior, dry, of 3 carpels, forming
a i -celled pod, with 3 valves, which fall away from a
framework. Seeds many, without albumen.

(f ) Dehiscent fruits of several free carpels.

Columbine, Aconite, Larkspur. — Fruit su-
perior, of 3 or more dry pods, splitting longi-
tudinally down the inner face. Seeds numerous,
albuminous.

129. The contrivances for the dispersion of fruits
and for their becoming fixed to the ground, are very
numerous, and afford most interesting studies. Many
have winged appendages belonging to the carpels
(maple, ash), or hooks by which they attach them-
selves to the fur of animals (cleavers), or wings formed
of accessory organs (bracts of lime), or hooks, or spines
(involucres of beech, chestnut, burdock). Others
have fine hairs (pappus), formed by the calyx, (dande-
lion, thistle) ; others have a sticky surface, or one that
gets sticky when the fruit falls on moist ground suitable
for its germination (groundsel); whilst still others attract
birds by their smell, colour, or sweetness, and are
hence transported by them. Lastly, a few burst open
with elastic force, the valves acting as pop-guns, and
scattering the seeds abroad (balsam).

90 SCIENCE PRIMERS. [xxii.

XXII.— THE SEED.
TESTA, ALBUMEN, EMBRYO.

130. The seed consists of the embryo (Par. 35)
and its coverings (integuments), and sometimes
albumen ; it is the ovule fertilized and arrived at
maturity, at which period it has become independent
of the parent plant ; it is attached to the pericarp by
a short or long cord, funicle (Par. no), through
which it derived nourishment from the parent.

131. The integuments are usually double, the two
coverings sometimes corresponding to the two coats
of the ovule (Par. 114); the outer (testa) is generally
the harder and thicker, and is sometimes, but very
rarely, juicy (pomegranate). Two points should be
carefully noted on the testa — the scar (hilum)
indicating its point of attachment, and a minute
hole (micropyle) by which the pollen-tube entered
the ovule (Par. 114). The radicle of the embryo
almost always points to this hole. In some seeds
a ridge (raphe) passes from the funicle to the
opposite end of the seed, indicating the position of
the nourishing vessels that go to the base of the
nucleus (Par. 114), where they sometimes expand into
a dark spot. In many palm seeds the raphe sends
branches of vascular bundles through the testa.

132. The embryo is a rudimentary plant (Par. 35)
with partially-developed organs. The radicle of the
embryo is developed first, and is hence to be found
next the micropyle (Par. 131). When fully formed the

xxn.] BOTANY. 91

embryo consists of a cotyledon or cotyledons, a
plumule, and a radicle; of these parts each cotyledon
represents a leaf, the plumule and radicle together
form an axis, of which the first is an ascending portion
and becomes a stem, the latter a descending portion,
giving origin to the root. The plumule is, in many
plants, not developed till after germination.

There are two principal kinds of embryo amongst
flowering plants, the mono- and di-cotyledonous; both
have cotyledon, plumule, and radicle, but they differ
most materially in their structure and mode of
growth.

133. The monocotyledonous embryo is often a
cylindrical body, of which the upper part is the
cotyledon, and usually presents a longitudinal slit or
depression in which the plumule lies, the lower part is
the short, blunt radicle. In germination the plumule
ascends, developing alternate, often sheathing, leaves;
whilst the radicle either elongates for a short time and
is then replaced by adventitious roots or is itself
entirely undeveloped, but gives 'off sheathed adven-
titious roots (wheat, Fig. 12).

134. The dicotyledonous embryo is more compli-
cated; its two cotyledons are often very large and equal
and are always opposite, whilst the radicle is small and
often short. The cotyledons maybe thick (pea, horse-
chestnut, acorn), or thin (maple), flat (castor-oil), or
folded (mallow, mustard), or crumpled (convolvulus),
veined with vascular bundles or not. The cotyledons
may remain underground and suffer no change till they
shrivel or decay (pea, bean, oak), or be carried up and
become green leaves (mustard, Fig. n) before the
plumule is well developed. In germination the plumule

92 SCIENCE PRIMERS. [xxn.

ascends, rarely developing sheathing leaves, and the
radicle elongates and branches.

135. The albumen consists of a mass of cells con-
taining starch, albuminoids (Pars. 17, 20), &c., provided
for the nourishment of such embryos as possess it.
It is usually formed within the embryo-sac (Par. 116).
There is no organic connection whatever between the
embryo and the albumen with which it is in contact,
but yet the growing tissues of the former withdraw
nourishing matter from the most distant part of the
latter.

136. Seeds, like fruits (Par. 129), are provided with
various means for aiding their dispersion, in the
shape of accessory growths, colour, juicy coverings,
&c. Many have the testa produced into a thin wing
(pine-seeds), or are covered with long hairs (cotton),
or have a tuft of hairs at one end (willow-herb), or at
the base (willow) ; others become mucilaginous when
moist, and thus adhere to the ground on alighting at
a fit spot for growth (cress) ; or are supposed to attract
birds by their brilliant colours, as certain tropical
plants of the pea tribe, the pods of which open so as
to expose the seeds ; others have a juicy testa (pome-
granate, magnolia, pseony) ; and still others, a fleshy
cup or covering (an aril) formed by a growth from
the funicle (Par. 130) (passion-flower and spindle-
tree). The nutmeg-tree has a i -seeded fruit like
a peach, that splits open and exposes the nutmeg,
surrounded by an aril of a brilliant scarlet colour :
this aril no doubt attracts pigeons, which swallow
the nutmegs, and transport them from island to island
of the Moluccas.

137. The vitality of seeds is very variable as to

xxiii.] BOTANY. 93

duration. Amongst instances of fugacious vitality are
acorns, which germinate at once, and maple-seeds.
As a proved instance of persistent vitality, the sacred
bean of India is the most authentic ; one such taken
from a herbarium upwards of one hundred years old,
having germinated. Wheat is said to keep for seven
years at the longest. The statements as to mummy
wheat are wholly devoid of authenticity ; as are those
of the raspberry seeds taken from a Roman tomb.
On the other hand, that seeds may remain buried
alive in the soil for many years is rendered most
probable by the fact of charlock and broom appearing
suddenly and in quantities in newly-turned-up soil
that had not been disturbed for long periods. It is,
however, difficult to believe that such a moist complex
substance as living protoplasm can resist chemical
change sufficiently long to favour the idea that seeds
have lain buried alive in the soil for many hundred
years.

XXIII.— SURFACE COVERINGS AND APPEN-
DAGES.

138. These are either exudations from the cells
of the epidermis (Par. 6), or modifications of the
epidermal cells, or cellular growths from them. They
serve very various and totally distinct functions, all
necessary to the health, growth, or propagation of the
plant. The principal of them may be most instruc-
tively classed under their apparent uses : —

(a) Protective.— The simplest of all is the bloom
of the grape, cabbage-leaf, pea-pod, &c. It consists
of a secretion of wax, which being insoluble in water is

94 SCIENCE PRIMERS. [xxin.

probably intended to prevent its injurious effects on
the subjacent tissues. Others are hairs and scales.

Hairs are either prolongations of epidermal cells,
or single long cells of the epidermis (cotton), or
strings of such cells (spider-wort). They are protec-
tions against wet, cold, and the effects of drought on
the subjacent tissue. They are often branched (mal-
low) or radiate from a point, like a star; when the
rays of such a star are combined the result is a scale
or scurf (elaeagnus.)

(b) Defensive. — The sting of the nettle is a single
awl shaped rigid cell, with a swollen base, in which an
irritating fluid is secreted. On piercing the skin the
point breaks off, and the fluid is deposited in the wound.

(c) Attractive. — Hairs that secrete a fluid which
is sugary or odorous are very common (sweet briar),
and are no doubt intended to attract birds and insects
for the purpose of fertilizing the flowers or carrying off
and thus dispersing the seeds.

(d) Nutritive. — The glandular hairs of the sun-
dew, which both retain the insects that visit the leaves
(thus acting also as detentive organs) and absorb
nutriment from them. The sticky stems of the catch-
fly, and many other plants, probably serve the same
purpose.

(<?) Scansorial (aids to climb). — Such are especi-
ally prickles, which are hooked cellular growths from
the epidermis. By their aid the bramble and many
roses climb bushes, and so get to the light. By their
aid the rope-like rattan-canes of the Indies ascend the
loftiest forest-trees, and expand their crown of foliage
and flowers in the sun. They must not be confounded
with spines (Par 65).

xxiv.] BOTANY. 95

XXIV.— GYMNOSPERMOUS PLANTS.

CONIFERS AND CYC ADS.

139. There is a small but well-known group of
flowering-plants that differs so much from all others
that it requires to be described separately. Its princi-
pal members are the coniferae, plants which include
pines, firs, larches, cedars, yews, cypresses, junipers,
araucarias, the wellingtonia, &c., and the cycads,
palm-like plants of warm or hot countries. All are
long-lived trees or shrubs, whose flowers have no
perianth, and are almost invariably produced in male
and female cones, consisting of scales, forming a close
spiral round a woody axis. They are believed to
have been inhabitants of the globe for a much longer
period than any other flowering plants.

140. Gymnosperms resemble dicotyledons in
the form and germination of the embryo, which
however has often three or more cotyledons, in the
exogenous growth of their stem (Par. 56), and they
resemble all other flowering plants, in having stamens
and ovules. They differ from dicotyledons in the
layers of wood which are formed after the first year
being destitute of vessels ; in the universal presence
of disks with central pores on the wood-tissue ; and
from all other flowering plants in the peculiar structure
of the pollen, in the ovules not being inclosed in
an ovary, and in the development of the embryo.

141. Their stamens for the most part consist of
one or more anther-cells without filaments, situated
on the under-surface of the scales of* the male cone.
Their pollen does not produce a tube from its inner

96 SCIENCE PRIMERS. [xxiv

membrane (Sect. 108), but does so from a group of
cells that form in its cavity.

142. Their ovules are borne on the upper surface
of the scales of the female cone, which scales con-
sist of an open carpellary leaf seated upon and com-
bined with a bract (these are undistinguishable in the
Scotch fir, but distinguishable in the larch). They
resemble the ovules of flowering-plants, and like them
may have one or two coats, and be straight or inverted
through the unequal growth of one side (Par. 115).
The embryo-sac becomes filled with cellular tissue at
an early period. Within this tissue, beneath the upper-
most layer of cells, forming the top of the sac, several
larger cells appear, and form as many secondary
embryo-sacs. At the same time, that one cell of
the uppermost layer which lies immediately above
each secondary sac, divides longitudinally into four,
leaving a canal between for the passage of the pollen
tube.

143. Fertilization takes place by a pollen-grain,
carried by the wind, alighting on the top of the nucleus
of the exposed ovule, and sending its tube through the
cellular substance of the nucleus, down to the primary
embryo-sac. There it reaches the passage between
the four cells above a secondary sac, traverses it, and
touches the latter. On this contact taking place
the contents of the secondary sac are divided by a
transverse partition into two portions, the lower of
which subsequently again divides and forms four
filaments that descend into the tissue of the primary
sac and nucleus. In the nucleus each filament begins
to form an embryo by cell-division at its extremity,
but only one embryo usually arrives at maturity.

xxv.] BOTANY. 97

144. Thus in gymnosperms, instead of the nucleus
of the ovule containing a simple embryo-sac with
one germinal vesicle which gives origin to an embryo,
several secondary sacs are formed within the primary
one, of which each gives origin to four embryos ; and
as some gymnosperms have eight or more secondary
embryo-sacs each producing four embryos, it follows
that in such cases out of thirty-two commencements of
embryos all but one are suppressed.

XXV.— CLASSIFICATION.

145. The objects of a classification of plants
are, to place before the mind, in a clear manner, the
relationships that exist between them, and to express
these relationships in precise terms, so that they may
be communicated orally or in writing, and thus facili-
tate and advance a knowledge of plants.

146. The idea carried out in all methods of
classifying plants is derived from the fact, that they
appear to be related to one another as are the
members of the human race, lineally and collaterally ;
and whatever theory may be accepted for the origin
of their kinds (species), the results obtained by
classifying plants, and the mode of reasoning followed
in detecting their relationships, are the same as what
would follow were they proved to have descended
from one or more common ancestors.

147. For the purposes of classification a nomen-
clature is essential, and that nomenclature is the best
which conveys briefly and in expressive terms some
distinguishing attribute of the plant or group of plants

98 SCIENCE PRIMERS. [xxv.

to which its terms are applied. For this purpose
Latin and Greek are much used, because they are
acquired by educated peo'ple in all civilized countries,
and because they lend themselves by their flexibility
and harmonious sounds to the compounding of
names.

148. The names in constant use for the purpose
of the classification of the members of the vegetable
kingdom are individual, variety, species, genus, order,
class, sub-kingdom. When referring to a plant, its
generic and specific names are both used, putting
the generic first if the Latin language is used, and
the specific first if the English (as Rosa canina, Dog
rose).

A species is an aggregate of individuals which
have been proved to have descended from a common
ancestor, or are so similar to one another that they
may be presumed to have done so. But as no two
individuals are exactly alike, and as the number of
instances of unlikeness to the parent form increase
with the number of individuals produced by seed, it
becomes often difficult to define the limits of a species.
These unlike individuals are called varieties (Par.
150); and the descendants of a well-marked variety
that propagates its peculiarities with much constancy
by seed is called a race, and sometimes a sub-
species.

A genus is an assemblage of species resembling
one another in most important points of structure, as
the various kinds (species) of oak, elm, willow, &c.

Orders, also called Families are assemblages of
genera agreeing in certain marked characters. These
agreeing characters are sometimes obvious to the com-

xxv.] BOTANY. 99

mon observer, as those of the carrot and parsnip, which
are two genera of one order ; at other times they depend
on characters of flower and fruit that are not recognized
without botanical knowledge, as those of the butter-
cup and larkspur, which, though so unlike, are members
of one order.

Classes are groups of a still higher value, as those
of monocotyledon and dicotyledon. All classes are
grouped under the two sub-kingdoms of flowering
and flowerless plants which constitute the vegetable
kingdom.

149. Individuality. Plants, especially perennial
ones, are often regarded as composite beings, or aggre-
gates of individuals, because their buds may be
detached and become separate individuals; because
many parts annually die, and are replaced by similar
parts ; and because much of the substance of a tree
or bush dies and remains as dead matter throughout
the future life of the plant, forming a support as it
were for the fresh buds developed from the living
tissues that surround it. But whereas it is only of
some plants that the buds are capable of becoming
separate individuals, there are others of which single
cells are capable of playing the same part ; so that if
the answer to the question of " What is an individual
plant?" is to depend on this power of its parts to
maintain a separate existence, it is a purely speculative
one, and we are reduced to accept the only alternative
of regarding each specimen as an individual, so long
as if remains an organic whole.

150. Origin of Varieties. — The result of cross-
fertilization (Par. 119) is that the qualities of two
distinct individuals are combined in the embryo and

10

ioo SCIENCE PRIMERS. [xxv.

appear in the future plant ; whence it follows that the
progeny of any individual plant which has been fer-
tilized by another individual must differ more or less
from that which bore it. Also seeds taken from dif-
ferent parts of the same plant being differently nourished
will produce plants showing different amounts of un-
likeness to the parent ; and these sources of unlikeness
are further affected by the conditions under which the
seeds germinate and the future plant grows.

151. Profiting by these facts, gardeners highly manure
certain plants, and cross-fertilize others, in order to
obtain new strains, as they are called ; and by raising
plants from all the seeds that ripen under these con-
ditions they obtain a large choice of individuals
differing in various degrees from their parents.

152. Nature proceeds more slowly: very few indeed
of the seeds shed in a state of nature produce plants
that arrive at maturity ; most perish from falling on
stony ground ; or from drought ; or are eaten by
beasts, birds, or insects ; or if they grow, the young
plants are choked or eaten, or otherwise killed. Of
those that survive, such as have their parents' con-
stitutions are the most numerous, and such will
most resemble their parents in outward character.
Hence marked variations, though so easily produced
in a garden, are comparatively rare in a state of
nature.

153. Origin of Species, — There are two opinions
accepted as accounting for this ; one, that of inde-
pendent creation, that species were created under
their present form, singly or in pairs or in numbers :
the other, that of evolution, that all are the de-
scendants of one or a few originally created simpler

BOTANY.

forms. The first doctrine is purefy^ speculative,
able from its very nature of proof \ &acfring nothing,
and suggesting nothing, it is the d^sjiair^m^estigajtqrs
and inquiring minds. The Other; 'whether C7dd V&ofly/
or in part only, is gaining adherents rapidly, because
most of the phenomena of plant life may be explained
by it ; because it has taught much that is indisputably
proved ; because it has suggested a multitude of pro-
lific inquiries, and because it has directed many in-
vestigators to the discovery of new facts in all depart-
ments of Botany. It regards as proved — i. That
the descendants of every plant departs (varies) more
or less in character from its parents. 2. That of these
variations some are better fitted than others, and
even sometimes than their parent was, to survive
in the area the plant inhabits. 3. That the con-
ditions of the area are, like the individuals, vari-
able. 4. That the number of deaths previous to
maturity amongst the descendants is enormously
greater than that of survivors, and that these deaths
are due to the conditions of the area not having-
suited them. 5. That the descendants (variations)
best fitted to thrive under the conditions of the area
will be the survivors. 6. That these variations will
hence ultimately in certain places supplant the parent
form. 7. That the difference between a species and
a variety being one of degree only, the variations ac-
cumulated through successive generations will become
specific, and these again by a like process generic,
and so on.

154. The chief apparent difficulty in accepting this
doctrine is to assign sufficient cause for the apparent
fixity of a species for even a limited period. This

102 SCIENCE PRIMERS. [xxvi.

difficulty is-met/foy the consideration that no great
departure from the parent form (which has itself sur-
vived) can, * as a rule, be suited to the conditions of
the area; and that variation can have but narrow
limits during any one or a few generations, just as
the changes in natural conditions are slight during
short periods.

155. Hybrids are the result of the ovules of one
species having been fertilized by the pollen of another.
' They are called mules, and are rare in nature but
easily produced by art. Many grow rapidly and
flower copiously, but do not fertilize their ovules,
owing to the imperfection of these or of their pollen ;
hence they rarely ripen seed. On the other hand,
they often seed abundantly when fertilized by the
pollen of one of their parents.

By hybridizing many more valuable results in a
horticultural point of view are produced than even
by cross-fertilizing (Par. 151); a scentless species, if
fertilized by the pollen of a scented one, may produce
a scented hybrid ; and by hybridizing, the qualities of
size, form, and colour of flower, fruit, and leaf, hardi-
ness, early or late flowering, &c., may be combined
in plants whose parents each possessed one only of
these qualities.

XXVI.— PHYSIOLOGICAL EXPERIMENTS.

156. Absorption and evaporation of water.

— Take up three plants of the buttercup, carefully by
the roots; leave one (No. i) on the table; place
another (No. 2) with its roots in water; hang the

BOTANY.

103

third (No. 3) upside down over a tumbler of water
with some of the leaves in the water, but the root
exposed. In due time No. i will have faded ; No. 2
will be quite fresh ; No. 3 will have the parts not in
the water faded. No. i shows that water contained
in the plant has evaporated from its surfaces ; No. 2
that the water has been absorbed by the root and
conveyed to the leaves ; No. 3 that the immersed
leaves have not supplied the emerged portion of the
plant with water.

157. Decomposition of the carbonic acid of
the air by plants in sunlight. — Take a bunch of

FIG. 68

fresh green leaves— water-cresses answer well— and
place them in a large bottle, then fill the bottle quite
full of fresh spring water, so that no bubble of air is
left in the bottle. Turn the mouth of the bottle, full
of water and leaves, downwards into a basin full of
water, and place the bottle and basin in the strong
sunlight for an hour or two. If the leaves be then
carefully examined they will be found to be covered
with small bubbles, and that more of these bubbles

104 SCIENCE PRIMERS. [xxvi.

have collected at the top of the bottle. These
bubbles consist of pure oxygen gas derived from the
carbonic acid contained dissolved in the spring water.
This shows that plants have the power in presence
of sunlight of decomposing carbonic acid, taking
the carbon to build up their stems, leaves, &c., and
setting free the oxygen as a gas. Now repeat the
experiment ; but instead of placing the bottle of spring
water containing the leaves in the light, put it in a
dark cellar. There will then be no formation of
bubbles of oxygen gas, even after standing for many
hours. This shows that sunlight is necessary in order
that green plants may decompose carbonic acid, and
is therefore necessary for their growth.

158. Respiration. — In the green parts of plants
the giving off of carbonic acid gas, which takes place
in the respiration of all living things, is 'not observed
owing to the action of chlorophyll in decomposing
carbonic acid. It becomes, however, very evident in
parts which are not green.

Fill one-third of a wide-mouthed stoppered bottle of
rather less than two quarts capacity with soaked peas,
or with the expanding flower heads of camomile or
daisy. If the bottle is carefully opened after several
hours the air contained will be found to extinguish a
burning taper. This is due to the presence of carbonic
acid gas.

By taking special precautions and using a very
delicate thermometer, it is possible to show that a
distinct rise of temperature takes place during the
evolution of the carbonic acid. An illustration on a
large scale of this rise of temperature is afforded by
malt during its manufacture.

xxvi.] BOTANY. 105

159. Transpiration. — Cut two branches of the
same plant. Put one in a warm, the other in a cool
place. Note that the former fades soonest. With a
sufficiently delicate pair of scales this may be shown to
arise from a larger loss of water. Evaporation proceeds
more rapidly in warm air than in cold, because the
former is able to hold a larger amount of moisture.

160. Germination. — Suspend an acorn or horse-
chestnut by a piece of twine in the neck of a wide-
mouthed bottle, and above the surface of some water.
Place the bottle in a warm place. The water will
evaporate and moisten the suspended seed, which will
germinate. The condensed water is necessarily pure,
and it is evident that this is the only material required
by seeds in order to germinate.

Repeat the experiment with two sets of bottles ;
place some in a warm, others in a cooler place.
Compare the time in which germination is effected.

161. Effect of light on chlorophyll. — Sow
some cress seed, and keep the pots in a dark place.
The seed-leaves will be pale. Remove part of the
germinating plants to the light ; the seed-leaves will
become green. Compare their progress in this respect
with those kept in the dark.

Press closely upon the surface of a geranium leaf
some pieces of tin-foil, and afterwards expose the leaf
for five to ten minutes to bright sunlight. The parts
covered with the tin-foil will be found to have a darker
colour than the rest. The lighter tint is due to the
movement of the chlorophyll granules under the in-
fluence of light from the upper and lower surfaces of
the cells to their sides.

162. Colour of flowers independent of light.

io6 'SCIENCE PRIMERS. [xxvi.

— Grow hyacinths of different colours in a completely
dark cellar. They will expand their leaves and
flowers. The former will be pale, but the latter will
develop their proper colours.

163. Heliotropism. — Place a pot of germinating
cress before a window. It will be found after a few
days that the stems are turned in the direction of the
light. This is due to the fact that light retards growth,
and therefore the sides of the stem turned to the light
and away from it come to have different lengths, and
the stem consequently bends.

It follows from this that if a pot of germinating
cress be shaded equally all round, the plants will grow
faster than if not so shaded.

Grow some germinating cress in a closed box in
one side of which a piece of dark blue glass has been
introduced ; there will be no curvature in the growth.
Repeat the experiment substituting a piece of deep
red glass ; curvature will take place as with ordinary
daylight. This proves that the heliotropic effect of
light is due to the rays belonging to the red end of
the spectrum.

xxvii.] BOTANY. 107

XXVII.— A SCHOOL GARDEN OF FLOWERING
PLANTS.

The following is a list of such easily procured
and easily cultivated plants as will afford the teacher
ample materials for instruction in Elementary Botany,
will give an idea of the natural arrangements of
flowering plants, and will convey a practical know-
ledge of many useful vegetables cultivated in all
temperate regions.

This list is capable of indefinite extension according
to the knowledge of the teacher, the size of the
garden, the nature of its soils, the means at hand of
procuring roots or seeds, and the labour that can be
obtained for cultivating them. Abundant specimens
of each should be grown, so that every pupil may have
plenty to cut up and examine with the teacher.

The trees and shrubs marked with an asterisk (*)
cannot well be introduced into such a garden amongst
the herbaceous plants, but their names should be
introduced in their proper places, and the pupil's at-
tention should be directed to the plants themselves in
neighbouring woods and plantations.

SERIES I. — Angiosperms. Flowering plants having the
ovules inclosed in an ovary. Woody tissue containing
abundant vessels.

CLASS I. DICOTYLEDONS.

DIVISION I. — Flowers usually with both a calyx and a corolla
— the latter of free petals. Stamens inserted close under the
ovary (not on the calyx). Ovary always superior.

Order Ranunculacecs. — Clematis, anemone, butter-cup, hellebore,

ficaria, columbine, larkspur, aconite, pseony.
O rd er Bcrberidca. — Barberry.
Order Papaveracece. — Poppy, celandine.

io8 SCIENCE PRIMERS. [xxvu.

Order Fumariacea. — Fumitory

Order Crucifercz. — Stock, wallflower, arabis, cabbage, shepherd's

purse, honesty, mustard, cress, candy-tuft, sea-kale, radish,

charlock, turnip.
Order Resedacece. — Mignonette.
Order Cistinea. — Rock- rose, gum cistus.
Order Violaretz. — Heartsease, dog-violet.
Order Caryophyllea. — Pink, sweet william, catchfly, stitch wort,

spurrey, chickweed.

Order Hypericinetz. — Tutsan, St. John's-wort.
Order Malvacea. — Marsh mallow, lavatera, common mallow.

* Order Tiliacece. — Lime.
Order Linece. — Flax.

Order Geraniacece. — Crane's-bill, stork's-bill, pelargonium, tro-

pseolum, balsam.
Order Vites. — Grape-vine, Virginia-creeper.

* Order Ilicinea. — Holly.

DIVISION II. — Characters of Division I., but stamens inserted
upon the calyx and ovary either inferior or superior.

* Order Sapindacece. — Maple, horse-chestnut.

* Order Celestrtneiz. — Spindle-tree, buckthorn.

Order Leguminosce. — Furze, broom, * laburnum, clover, lucerne,

saintfoin, pea, bean, vetch.
Order Rosacece. — *Plum, * cherry, spiraea, bramble, raspberry,

strawberry, cinquefoil, dog-rose, sweetbriar, *pear, * apple,

* hawthorn.

Order Saxifragece.— London pride, gooseberry, currant.
Order Droseracetz.-— Sundew.

Order Crassulaceiz. — Orpine, stone-crop, house leek.
Order Onagrarietz. — Willow-herb, evening primrose, enchanter's

night-shade.

Order Lythracea. — Loose-strife.
Order Cucurbitacea . — Bryony, gourd.
Order Umbtlliferce. — Pennywort, hemlock, celery, caraway.

chervil, fennel, -parsley, coriander, fools'-parsley, carrot,

parsnip, cow-parsnip.
Order Arahacea. — Ivy.
Order Cornaccce. — Cornel, laurustinus.

DIVISION III. COROLLIFLORAL. — Flowers with both calyx
and corolla, the latter usually of combined pieces. Stamens
usually inserted upon the corolla.

SUB-DIVISION I. — Ovary inferior.

Order Caprifoliacece. — Guelder-rose, elder, honeysuckle.

xxvii.] BOTANY. 109

Order Rubiacea. — Madder, bedstraw, cleavers, woodruff.

Order Valerianea. — Valerian, corn -salad.

Order Dipracea. — Teazle, scabious.

Order Composites. — Cornflower, thistle, burdock, butter-bur, colts-
foot, single aster, daisy, golden rod, sun-flower, chamomile,
milfoil, corn marigold, tansy, wormwood, groundsel, chicory,
goatsbeard, lettuce, dandelion, sow-thistle, hawkweed.

Order Campanulacea. — Lobelia, rampion, campanula, Canter-
bury bell.

Order Vaccinieac. — Bilberry.

SUB-DIVISION 2. — Ovary superior.

Order Ericacece. — Arbutus, heath, ling, rhododendron.

Order Oleinea. — Privet, *ash, lilac, jasmine.

Order Apocynea. — Periwinkle.

Order Gentianea. — Centaury, gentian.

Order Polemonia^ece. — Jacob's ladder, phlox.

Order Convolvulacece — Convolvulus, dodder.

Order Boraginecz. — Bugloss, borage, comfrey, lungwort, forget-
me-not.

Order Solanea. —Henbane, nightshade, potato, deadly night-
shade, tobacco, thorn-apple.

Order Plantaginea. — Plantain.

Order Scrophularinea. — Mullein, toad-flax, snapdragon, mimulus,
fDxglove, speedwell, yellow rattle.

Order Labiata.— Mint, marjoram, thyme, balm, sage, prunella,
horehound, deadnettle, rosemary.

Order Verbenace<z. — Vervain.

Order Primulacea. — Primrose, cowslip, Lysimachia, pimpernel.

Order Plumbaginece. — Thrift, statice.

DIVISION III, — Flowers with a single perianth.

Order Polygonece. — Bistort, buckwheat, dock, rhubarb.

Order Che.nopodiaceit. — Beet, spinach, goosefoot, orache.

Order Thymelece. — Daphne.

Order Elceagnece. — Sea buckthorn.

Order Aristolochiea. — Asarabacca, birthwort.

Order Euphorbiacece. — Spurge, castor oil, dog's mercury, box

Order Urtic'tz. — Nettle, pellitory, *fig, * mulberry.

Order Cannabinece. — Hop, hemp.

Order Ulmacece. — Elm.

DIVISION IV. — Flowers usually without obvious perianth.

Order Salicinea. — Poplar, willow.

Order Cupuliferea \. — Oak, beech, hazel, hornbean, chestnut.

i io SCIENCE PRIMERS. [xxvn.

CLASS II.— MONOCOTYLEDONS.

DIVISION I. — Flowers with a distinct perianth.
SUB-DIVISION I. — Perianth superior.

Order Orchidea. — Orchis, helleborine, lis.era.
Order Iridece. — Crocus, iris, gladiolus.
Order Amaryllidecz. — Narcissus, snowdrop.
Order Dioscorea. — Black bryony.

SUB-DIVISION 2.— Perianth inferior.

Order Betulacea. — Birch, alder.

Order Alismacece. — Water plantain, flowering rush.

Order Liliacea. — Asparagus, butcher's broom, lily of the valley,
Solomon's seal, squill, star of Bethlehem, onion, fritillary,
tiger lily, tulip, colchicum, crown imperial, hyacinth.

Order Juncea. —Rush, wood-rush.

DIVISION II. — Flowers without a distinct perianth.

Order Aroidea. — Cuckoo-pint.

Order Typhacea. — Bur reed, reed mace.

Order Cyperacea. — Bulrush, cotton-grass, galingale, sedge.

Order Grammes. — Foxtail -grass, canary grass, vernal grass,
bent grass, millet grass, oat, reed, cocksfoot grass, couch
grass, meadow grass, quaking grass, fescue grass, broom
grass, wheat, barley, rye.

SERIES II. — Gymnosperms. Flowering plants with the
ovules naked. Woody tissue destitute of vessels (except that
of first year).

Order Cotoifertz. — Juniper. * pine, yew, cypress, arbor-vitse,
* cedar, * larch, * spruce.

XXVIII.]

BOTANY.

XXVIII.-

-SCHEDULES FOR EXERCISES ON
LEAVES AND FLOWERS.

The first of these schedules is similar to that de-
vised by the late Professor Henslow of Cambridge
as a means of training the children of a village school
in habits of accurate observation, by examining the
structure of flowers. I have added one for leaves,
which is even simpler and quite as useful for begin-
ners ; it is adapted for trees and shrubs, but may be
extended and modified so as to embrace herbs, in
which the stem- and root- leaves often differ in shape.

Blank schedules should be kept in great numbers
and freely used by the pupils.

NAME OF
PUPIL

FLORAL SCHEDULE.
BUTTER-CUP.

DATE AND PLACE WHERE
GATHERED.

Organ

No.

Insertion
whether free or
combined

Whether
superior or
inferior

Remarks

Calyx
Sepals

5

free

inferior

green, hairy

Corolla
Petals

5

free

inferior

yellow, shining

Stamens

many

free

inferior

crowded, with
filaments

Pistil
Carpels

many

free

superior on an
elevated
receptacle

crowded, in a
round head,
style o

Ovules or seeds
in each carpel

i

at the base of
the cavity

11

112

SCIENCE PRIMERS.

[xxvin

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INDEX.] BOTANY. 113

INDEX.

The plants enumerated below are, with few excep-
tions, easily procured, either from woods, fields, or
shrubberies, or from gardens ; they should be used in
a fresh state when possible, though many may be dried
flat between paper so as to shew their instructive parts.
Some, as wheat-ears, acorns, peas, &c., should be kept
dry in quantities to be used for exercises ; others, as
strawberries and such soft fruits, may be preserved in
alcohol diluted with water. Lastly, a few objects must
be had of a dealer who prepares slices of woods, starch
grains, &c., for the microscope — these are marked with
an asterisk (*).

Acorn: 125, 127, 128; cup, 179; seed in, 137; embryo, 134

Alder: fertilization of, 120

Apple : vernation, 69 ; stipules, 68 ; flower, 85 ; calyx, 93 ;

corolla, 96; aestivation, 101 ; fruit, 125, 127, 128
Artichoke : Jerusalem
Ash: buds, 62; leaves, 68; fruit, 128, 129
Asparagus: stem, 59
Balsam : fruit, 129
Barberry: stamens, 106; fruit, 128
Barley: fruit, 128
Bean: fruit, 128; embryo, 134
Bedstraw : leaves, 68
Beech: buds, 66; vernation, 68; stipules, 68; fertilization, 1 20;

fruit, 128, 129

Beet : root, 45 ; * crystals in, 22
Bilberry: anthers, 106
Birch: catkins, 78
Burdock: fruit, 129
Box : absence of stipules, 68
Bramble: prickles, 4, 138; flower, 83; disk, 99; stamens, 104;

fruit, 128

Broom : vitality of seed, 137
Butcher's broom : * stem, 53, 59
Butter-cup: inflorescence, 77; flower, 85; calyx, 90; corolla,

93> 96; petals, 94; stamens, 104, 105; fruit, 128

114 SCIENCE PRIMERS. [INDEX.

Cabbage: bloom on, 138

Calycanthus: flower, 86

Campanula: flower, 85; calyx, 93; corolla, 96

Carrot: root, 45; inflorescence, 77, 78; involucre, 79; disk, 99;

fruit, 1.28

Castor oil: embryo, 134
Catchfly: stickiness of, 138
Cedar : leaves of, 68
Celandine: ovule, 114

* Cellular tissue, 6
Charlock : vitality of seed, 137

Cherry : vernation, 69 ; double flowered, 86 ; pollen, 108 ; *stone,

6, 14

Chestnut: fruit, 128, 129
Chickweed: inflorescence, 77
Clematis : stem, 4

Clover: inflorescence, 78; corolla, 95
Colchicum: corm, 52
Columbine: fruit, 128

Convolvulus: stem, 4; corolla, 96; aestivation, 101 : embryo, 134
*Cork, 6, 14

Cotton: seed, 136; hairs of seed, 138
Couch-grass, 47

Cowslip: root-stock, 49; inflorescence, 78; fruit, 128
Cress: seed, 136
Crocus: corm, 64; fruit, 128
Crown-imperial: nectary, 98

* Crystals, 22

Cnrrant: inflorescence, 78; fruit, 128

Daisy: inflorescence, 77, 78, 79; flowers, 85; stamens, 104;

fruit, 128
Dahlia: root, 45

Dandelion: leaves, 68; calyx, 91; pappus, 128, 129
Daphne: flower, 85

Deadnettle: leaves, 68; flower, 85; corolla, 95; fruit, 128
Dock: flower, 85
Dodder: stem, 2
Dog-violet: inflorescence, 76
Dracaena: *wood, 60
Elaeagnus: * scales, 138

Elder: *pith, 6; inflorescence, 77, 78; flower, 85
Elm : branching of, 66

* Epidermis : 7 1
Evening-primrose: pollen, 108
Ferns: vernation of, 69

INDEX.] BOTANY. 115

Fig: fruit, 125, 128

Flax: *bast cells, 8; *stem, 53, 54

Flowering-rush: inflorescence, 78

Foxglove : inflorescence, 78

Gooseberry: vernation, 69: flower, 85; fruit, 127, 128

Grape: tendrils of, 65; bloom of, 138

Grasses : vernation of, 69 ; sheathes, 68

Hawthorn: inflorescence, 78; spines, 65

Hazel: fertilization, 117; fruit, 128

Heartsease: stipules, 68; ovule, 116

Heath: anther, 106; fruit, 128

Holly: leaves, 68; fruit, 128

Honey-suckle: flower, 85; nectary, 98

Hop: stem, 51

Horse-chestnut: buds, 63; leaves, 68; inflorescence, 78; fruit,

128 ; embryo, 134

Hyacinth: roots, 45; root fibres, 42; bulb, 64; * spiral tissue, 9
Iris: root-stock, 52; vernation, 69; anthers, 106; fruit, 128
Ivy: roots, 47; leaves, 68
Kalmia: stamens, 102
Larch: leaves, 68; cone, 142
Larkspur: fruit, 128
Lilac: inflorescence, 78
Lime: *wood, 54; bast * cells, S; leaves, 68 b, d; inflorescence,

78; stamens, 104; disk, 82; fruit, 129
Magnolia: seeds, 136
Mallow: hairs, 138; flower, 85; aestivation, 101 ; stamens, 104;

fruit, 128; embryo, 134

Maple: leaves, 68; fruit, 127, 128, 129; seed, 137; embryo, 134
Mignonette: inflorescence, 78; aestivation, 101; disk, 99
Millfoil : leaves, 68
Mistletoe: anthers, 106; fruit, 127
Mulberry: fruit, 125, 128

Mustard: germination of, 33, 35—39; root hairs, 44; embryo, 134
Myrtle : stamens, 102
Narcissus, 85
Nepenthes: pitcher, 30

Nettle: * sting, 138; stamen, 102; fruit, .128
Nutmeg: fruit, 136
Oak: branching, 66; leaves, 68; stipules, 68; inflorescence, 78;

fertilization, 117; fruit, see Acorn
Oats: inflorescence, 78; fruit, 128
Olive: fruit, 128
Onion: bulb, 52
Orange: pulp, 6; disk, 99

ii6 SCIENCE PRIMERS. [INDEX.

Orchis: roots, 46; flower, 85; stamens, 104; pollen, 108; fer-
tilization, 103; fruit, 128
Poeony: seed, 136
Palm: seed, 131
Parnassus : grass of, 98
Parsley: leaves, 68 <?; inflorescence, 68
Parsnip: inflorescence, 78; fruit, 128

Pea : leaves, 68 ; stipules, 68 ; flower, 83, 85 ; corolla, 95 ;
stamens, 104; fruit, 121, 117, 128; bloom on, 138; seed,
33; germination, 35—39

Pear: vernation of, 69; fruit, 125, 128; grits, 6, 14
Pennywort : leaf, 68
Periwinkle: aestivation, 101

Pimpernel : inflorescence, 76; aestivation, 101 ; corolla, 96
Pine: *wood, 13, 140; leaves, 68;* * pollen, 141 ; cone, 125, 128;

fertilization, 120; seed, 136
Pink: inflorescence, 77; flower, 85
Plantain: inflorescence, 78; fertilization, 120
Plum: fruit, 128
Pomegranate: seed, 131
Poplar : inflorescence, 78
Poppy: fruit, 128

Potato: stem, 49; tubers, 64; fruit, 128
Primrose : flower, 85 ; calyx, 9 ; corolla, 93, 96 ; fertilization,

122; fruit, 128
Privet: leaves, 68
Quince: fruit, 128
Radish : root, 45
Raspberry: fruit, 128

Rose: prickles, 138; leaf, 68; stipules, 68; flower, 85; double
flower, 86; calyx, 93; stamens, 107; fruit, 125, 128

Rosemary: vernation, 68

Sacred bean of India : germination of, 137

Sarracenia : pitchers of, 30

Scabious: inflorescence, 78

Shepherds-purse : roots, 45

Snapdragon : inflorescence, 78 ; flower, 83 ; corolla, 95

Spiderwort: * hairs of stamens, 137

Spindle-tree : seeds, 136

Spines, 68

St. John's wort: stamens, 104

Star of Bethlehem : inflorescence, 78

* Starch, 6, 17

Stitchwort : inflorescence, 77

*Stomates, 27, 72, 75

INDEX.] BOTANY. 117

Strawberry: fruit, 125

Sundew: 30; glands, 138

Sweet-briar : hairs, 138

Sweet-william: inflorescence, 77

Teazle: inflorescence, 77

Thistle: stamens, 104; fruit, 128, 129; pappus, 91

Tiger-lily: bulbs, 4; roots, 52; buds, 63

Tulip : inflorescence, 76 ; flower, 85 ; double, 86

Turnip: root, 45

Valerian: pappus, 91

Venus's fly-trap : leaf, 30

Vine : tendrils, 4 ; vernation, 68

Violet: fruit, 128

Virginian creeper : tendrils, 65

Wall-flower: inflorescence, 77; disk, 99; fruit, 127, 128

Walnut : inflorescence, 78

Water-lily: flower, 86; stamens, 107

Wheat: flower, 85; fruit, 128; vitality of, 137; germination of,

133—139
Willow: vernation, 68; fertilization, 117, 120; fruit, 128; seed,

*34

Willow-herb; seeds, 136
Wood-cells, 7
Woodruff: leaves, 68
* Yeast plant, 14

TA U4J6/

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rEOGRAPHYj GIOEGS GROVE,

NGUSH GRAMMAR; DR, R. MOREIS,
NGLISH. LITERATURE s REV. STOPFO&P
BROOKE,

PHILOLOGY: J. PEILE, M.A.

GREEK. LITERATURE? R. C, JEBB, M. A.