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CONVERSATIONS
ON
VIE GE TABLE PHYSIOLOGY:
COMPREHENDING
THE ELEMENTS OF BOTANY,
WITH
'I' HEIR A PPLICATION TO A G RICULTURE.
BY THE AUTHOR OF
oxvrnsations on chexistry,” “NATURAL Philosophy,”
&c. &c.
WITH COPPERPLATE ENGRAVINGS.
iſºtim 390th :
PRINTED BY SLEIGHT & ROBINSON, No. 26 WILLIAM ST.
*In my whits, GALLAhr R AND white ; g. Ann c. And H. carvili.; E. Briss ;
‘ol.11ns Ann Hannay ; w. B. gillsy ; collins AND co. ; o. A. Rooksach; c. s.
*Rancis; J. Likavitt; J. P. Haven; williams murgess, Jr.-Hartford; it. And
I. HUNTINGTON-PHILADELPHIA ; John Grigg; ToweR AND HOGAN.
1830.
Science library
PREFACE.
•=sº
THE ſavourable reception which the former works of
the Author have met with, encourages her to offer this
volume to the public. In doing so, she cannot but feel
diffident of success, as the subject of the present work is
one with which she has but recently become acquainted.
Yet the source from which her knowledge of the vegeta-
ble creation is derived, makes her hope that this new
mode of studying Botany may be found interesting and
useful.
The reader will perceive that the facts and opinions
contained in the following pages, are almost exclusively
taken from the lectures of a distinguished professor of
Geneva. To him, indeed, whatever merit may be found
in this work, is due. The instruction and amusement
which the Author derived from his lectures, led her to
think that she might, under the form of Conversation,
convey a part of that interest to the minds of others. All
she can lay claim to, is having arranged the subject in
that form which has always appeared to her to possess
great clearness and advantage in fixing the attention of
young people.
In acknowledging her obligations for the encourage-
ment and assistance which that friend has so kindly
given her, she must, at the same time, consider herself
responsible for any errors or inaccuracies which, either
through inattention or want of knowledge, may have
crept into the work.
TABLE OF CONTENTS.
CONVERSATION I.
INTRODUCTION.
Distinction between Minerals and Organised Beings.—Dis-
tinction between the Animal and Vegetable Kingdoms.-
Effect of Vegetable Poisons on Plants.-Irritability and
Contractability of Plants.—Properties of Plants, relative to
Structure and to Vitality.—Organs of Plants of four kinds:
1. Cellular System. 2. Vascular System. 3. Tracheae.
4. Strangulated Vessels.-Fibres of Plants.--Layers of
Wood.—Cuticle. x - gº * * wº * Page 13
CONVERSATION II.
ON ROOTS.
Six Periods relative to the Nutrition of Plants : 1. Absorp-
tion by the Roots; they also fix the Plant in the Ground.—
Spongioles; suck up whatever is sufficiently minute to
enter their pores.—Fibrous Roots.—Creeping Root.—
Spindle-shaped, Tap, or Pivot Root.—Abrupt Root.—
Bulbous Root.—Tuberous or Knotted Root. - ſº 25
CONVERSATION III.
ON STEMS.
Subterranean Stems.-Willow Grass.-Neck of a Plant.—En-
dogenous Plants, or Monocotyledons.---Exogenous Plants, or
Dicotyledons.—Acotyledons.—Structure and growth of En-
dogenous Stems.--Ditto of Exogenous Stems.-Wood.—
Pith.-Medullary Rays of Cellular Tissue.—Perfect Wood.
—Alburnum, or new Wood.—Bark.-Rise of Sap. 34
CONVERSATION IV.
ON LEAVES.
Expansion of Leaves.—Sessile and articulated.—Pores or
Stomas.—Leaves divided into five classes: 1. Permated.
1*
vi
CONTENTS.
2. Palmated. 3. Peletated. 4. Pedalated. 5. Simple
Ribs.-Dissected Leaves.—Compound Leaves. -Stipula.
—Succulent Leaves.—Seminal Leaves, or Cotyledons.—
Primordial Leaves.—Bracteas, or Floral Leaves.—Radical
Leaves.—Arrangement of Leaves on the Stem.—Of Buds:
scaly or naked; of three descriptions of Germs; various
modes in which the Leaves are folded within the Bud.
—Deciduous Leaves.—Evergreens.—Fall of the Leaf. 49
CONVERSATION V.
ON SAP.
Sap absorbed by the Roots.—Bonnet's experiments on the
Ascent of Sap through the Stem.—Spring Sap to feed the
Buds.—Exhalation by the Leaves.—Quantity of Water
exhaled.—Chemical changes which take place in the
Leaves.—Purification of the Air by Plants.-Sennebier's
and De Saussure's Experiments.-Oxygen given out, and
Carbon retained, by Plants. - tº a tº - - 64
CONVERSATION VI.
ON CAMBIUM, AND THE PECULIAR JUICES OF PLANTs.
Cainbium descends through the Liber: its descent accelerated
by agitation.—Mr. Knight's Experiment.—Effects of Stakes
and Ligatures.—Of the Annular Incision.—Composition of
Cambium.—Water combined in Plants.—Internal Secre-
tions from Cambium.–Milk.-Resins.—Gum.—Gum Resin.
—Manna.—Essential Oil.–Fixed Oil.—Excretory Secre-
tions from Cambium.—Vapour of Fraxinella.—Odours of
Plants.-Bloom of Fruits.—Glands of Excretory Organs. 77
CONVERSATION VII.
ON THE ACTION OF LIGHT AND HEAT ON PLANTS.
Light enables Plants to decompose Carbonic Acid; produces

their Green colour; increases Absorption ; increases
Evaporation.—Effects of Intensity of Light.—Effects of
Deficiency of Light.—Action of Heat on Plants.---Effects
of Deficiency of Heat.---Freezing of Plants. - 9:0
CONVERSATION VIII.
ON THE NATURALISATION OF PLANTS.
Plants more affected by change of Temperature than by change
of Air, Moisture, or Soil.---Habits of Foreign Plants....
CONTENTS. vii
Directions for transplanting delicate Plants from a warmer
climate.---Ditto from a colder climate.---Construction of
Hot-houses and Green-houses. - * > tº a & 105
CONVERSATION IX.
on THE Action of the ATMospher E ON PLANTs.
Temperature of the Atmosphere.---Molsture.---Fogs.---Va-
pours. --- Wind.---Elevation and Teimperature at which
different trees will grow.- - - - - - 113
CONVERSATION X.
ON THE ACTION OF WATER ON PLANTs.
Water a vehicle of Food; dilutes Plants; is a vehicle for the
conveyance of Air.---River water preferable to that of Lakes
or Springs, for watering Plants.---Rich manure of Stagnant
Waters.---Watering Plants.---The Seed when Germinating,
when in Flower, ºft. in Fruit.--Seeds when Ripening.---
Natural means of Watering---Rain.---Dr. Well's Theory
of Dew.---Melted Snow. - - - - - 120
CONVERSATION XI.
ON THE ARTIFICIAL MODES OF WATERING PLANTS.
Watering Pots applicable only to Garden culture.---Watering
Green-house plants.---Watering by Infiltration, applicable
to delicate Plants and to meadows.---Watering by Irrigation.
---Meadows.---Rice Fields. The Pelagra.---Draining Land.
---Pontine Marshes.---Marshes of Holland and of Tuscany.
---Valley of Chiana. - - - - - - 130
CONVERSATION XII.
on the Acrion of soil on PLAnts.
Origin of the Formation of Soil.---Argillaceous Soil.---Sandy
Soil.---Sandy Deserts.---Sand of Rivers.---Steppes.---Sand
Hills.---Belgic Cultivation.---Campine.---On the Improve-
ment of Soil by Tillage.---Instruments of Agriculture.---
Of Ploughing. - tº gº tº gº tº us 141
CONVERSATION XIII.
THE ACTION OF SOIL, ON PLANT'S CONTINUED.
Improvement of Soil by Amendements; by Manure. 152
viii CONTENTS.
CONVERSATION XIV.
THE ACTION OF SOIL, ON PLANT'S CONTINUED.
Assolements.--System of Cropping, Simultaneous or in Ro-
tation.---Exudation of Plants.---Natural Forests.--Diffe-
rence of Annual and Perennial Plants.---Hoed Crops.---
Assolements of Trees.---Assolements of Belgium and of
Tuscany. - - - - - - - - 161
ON THE MULTIPLICATION OF PLANT8.
CONVERSATION XV.
ON THE PROPAGATION OF PLANT'S BY SUBDIVISION.
Two Modes of multiplying plants: by Seed, and by Subdivi-
sion.—Slips or Layers preserve the peculiar Qualities of
the Fruit, tend to diminish the Quantity of Seed, and to in-
prove the Fruit.—Germs.—Three Modes of subdividing
plants: 1. By Layers, various Modes of producing them.—
2. Layers above Ground.—3. Multiplication of Plants by Slips.
179
CONVERSATION XVI.
ON GRAFT ING,
The Graft or Scion.—Stock.-Grafting improves the Quality
of the Fruit.—Plants of the same Family can alone be graft-
ed on each other: other circumstances requisite.—Grafting
accelerates the period of bearing of Seedling Trees.—Me-
chanical part of the process.-Three Classes, Unitiges,
Omnitiges, Multitiges.—Various Modes of Grafting: 1.
By approach; 2. By Scions; 3. By Bourgeons or Buds, 8
*
CONVERSATION XVII.
on THE MULTIPLICATIon of PLANTs by see D.—THE FLOWER.
Organs of the Flower : Calyx, Corolla, Petals, Nectary,
Ovary or Seed Vessel, Carpel, Style, Stigma, Pistil, Sta-
mens, Filaments, Anthers.-Palm Trees.—Pedunculus.--
Torus, Pedicels, Receptacle, Inflorescence.—Calendar of
Flora.—Period of Flowering.—Mode of advancing or re-
tarding it.—Annular Section.—Fructification of the Seed
prevented by Rain. . - - - - - 195
CCNTENTS, ix
CONVERSATION XVIII.
ON COMPOUND FLOWERs.
A Head, or Capitate.—Receptacle.—Involucrum.—Compound
Flowers.-Calyx.—Elongation of Tuft or Pappus.-Coma.
—Akene.—Description of the Florets of a Compound
Flower. - - - - - - - - 206
CONVERSATION XIX.
ON FRUIT.
Conversion of the Flower into Fruit.—Pericarp.–Pea Pod.—
Legumen.—Epicarp.–Mesocarp.—Endocarp.--Fruits com-
posed of one Carpel.—Drupa, or Stone Fruits.-Fruits
composed of several Carpels resulting from a single Flower.
—Poeony.—Raspberry.—Fruits formed of several Carpels,
with the Calyx adhering.—Pome: Apple, Pear, Quince,
Medlar.—Bacca or Berry: Gooseberry, Grape, Currant,
Strawberry, Mulberry. — Fir Cone.—Akene. — Magnolia
("one.—Spanish Chesnut.—Horse Chesnut. tº- - 213
CONVERSATION XX.
ON THE SEED,
Structure of the Seed.—Spermoderm.—Testa.—Mesosperm.
—Endopleura.—Amnois.—Embryo Plant.—Cotyledons.—
Eye, or Hilum.—Cicatrix.-Albumen.—Nucleus, or Ker-
nel.–Germination.—Embryo, consisting of the Radicle,
Plumula, and Cotyledons.—Seeds in germinating require
Moisture and Subtraction of Carbon.—Oxygen required for
that ...-kº. injurious to Germination.—Tempera-
ture requisite.—Of sowing Seed.—Knight's Experiment on
the Direction of the Roots and Stems.-Modes of Sowing.
—Advantage of sowing thin.—Sowing in Gardens.—Hot-
beds, Garden-pots, &c.—Transplantation. º - 226
CONVERSATION XXI.
ON THE CLASSIFICATION OF PLANTS.
Necessity of some Mode of Classification.—Species.—Genera.
—Nomenclature.—Character of Genera. . . 239
CONVERSATION XXII.
on THE ARtificial systEts of classification of PLANts.
Analytic Method.—Flore Francoise.—System of Linneus,
245
M. GONTENTS.
CONVERSATION XXIII.
ON THE NATURAL SYSTEMS OF CLASSIFICATION.
Method of Tatonnement.—Method of general Comparison of
Mr. Adamson.—Method of Subordination of M. De Jussieu
and M. De Candolle—Comparative Importance of Organs,
—Organs of Reproduction and of Nutrition. - - 254
CONVERSATION XXIV.
ON BOTANICAL GEOGRAPHY.
Geographical Distribution of plants.—Difference of Habila-
tion and Station of plants.—Botanical Regions.—Their
Boundaries.—Various Modes of conveying Seed from one
region to another.—Proportion of Monocotyledons in the
Vegetable Kingdom.—Dycotyledons increase towards the
equator, Acotyledons towards the pole.—Ligneous plants
increase towards the equator, Herbaceous plants towards
the pole.—Annuals most common in Temperate Climates.—
Greater variety of plants in hot than in cold Climates.—
Social plants. - & ſº tº a gº * 264
CONVERSATION XXV.
ON THE INFLUENCE OF CULTURE ON VEGETATION.
Races.—Varieties and Variations, derived from Species.—
Influence of Culture in producing these Modifications.—
Hebrides.—Dutch Tulips.—Hydrangia.—Effect of Soil on
Variations.—Of Grafting.—Of Lopping.—Of Pruning Trees.
-Resinous Trees.—Green-house Plants.---Fruit Trees.
272
CONVERSATION XXVI.
ON THE DEGENERATION AND THE DISEASES OF PLANTS,
Degeneration of Organs producing Monstrosities.—Monope-
tals.—Failure of Seed.—Double-blossomed Flowers.-Con-
version of Petioles into Leaves.---Acacia of Arabia.---
Conversion of Petioles into Tendrils, of young Shoots into
Thorns.—Difference of thorns and prickles.—Diseases of
plants ranged under Six Heads: 1st Class, Constitutional
Diseases–Variegated Leaves.—2d Class, Diseases pro-
duced by Light, Heat, Water, Air, or Soil, improperly ap-
plied.—3d Class, Diseases from Contusions and external
Injury—Loss of Leaves and of Bark—Flagellations—Un-
skilful Pruning---Pollarding. - - - - 27°
CONTENTS.
CONVERSATION XXVII.
THE DISEASES OF PLANT'S CONTINUED,
4th Class, Diseases arising from the Action of Animals on
Plants---Devouring of Leaves by Quadrupeds or Insects, &c.
---5th Class, Action of Plants on each other---Parasitical
Plants---True and False Parasites, External and Internal---
Creeping Plants--- Rhizomorpha --- Mistletoe--- Cuscuta---
Orobanche---Fungi--- Erishe---Rhizotonia---Smut--- Rot---
Ergot-Rust—-6th Class, Diseases resulting from Age, and
causing the Death of Plants. tº º º - 289
CONVERSATION XXVIII.
ON THE CULTIVATION OF TREES.
*
Greatest Variety of Trees in tropical Climates.---Natural
Forests, tolerant and intolerant.---Thirty-four Species of
European Forest Trees, divided into Four Classes.---Various
Modes of felling Forests.---Wood for Fuel.---Cultivation of
single Trees.---Of lopping Trees.---Transplanting.---Sir
Henry Stewart's process.---Hedges.---Fruit Trees. T- 299
CONVERSATION XXIX.
ON THE CULTIVATION OF PLANT's WHICH PRODUCE FER-
MENTED LIQUORS.
Fermentation.---Of Sap.---Of Fruits.---Of Grain, producing
W. Beer, Cider, Perry.---History and Culture of 3.
IIlê. tº { . tº- tº- tº º tº gº
CONVERSATION XXX.
ON THE CULTIVATION or GRAssEs, TUBEROUS Roo'Ts,
AND GRAIN.
Meadows, perennial, renovated chiefly by the Spreading of the
Roots, require a moist Climate.---Sustain the Soil on De-
clivities.---Artificial Grasses, not forming permanent Mea-
dows, but entering into a Course of Cropping.—Clover.---
Saintfoin.---Lucerne.---Leaves used as Forage for Cattle.---
Tuberous Roots : Beets, Parsnips, Turnips, Carrots, Pota-
toes.—Of Corn : Straw, Grain, Flour, Husk, Beard.---Corn
divided into Three Series: 1. Wheat, Fermentation of
Bread, Gluten, Yest, Leven, Rye, Barley; 2. Series: Oats,
Philares, Rice; 3. Series: Corn having the pistils and sta
©
mens in different Flowers. ſ º & gº gº - 322
xii CONTENTS,
ſ
CONVERSATION XXXI.
on ole Aginous PLANts AND CULINARY vegetAP***
Fixed Oils.---Valatile Qils.---Fixed Oils ranged under Three
Heads: 1. Olive Oil, the produce of Warm Climaº, 2.
Nut Oil, of Temperate Climates; 3. Oils obtained from
Herbs....Of the Olive Tree.—Of Nut oil.---Oleºgnous
Herbs enter into a Course of Cropping-Rape.--Fºy--
Flax...Subterranean Arichis.--Culinary ‘Vegetables---
Strong-Flavoured : Artichoke, Asparagus, hubarb, Prussic
Acid, Celery.---Insipid plants.--From the Cruciform Fa-
inily are obtained Cabbages, Brocoli, Cauliflower, Turnips,
º Water Cresses, and Sea Cale.---From the “gu-
minous Family, Peas, Beans, Lentiles, and Kidney: *---
From the Cucurbitaceae Family, Cucumbers, Melons, and
Pumpkins.---From the Umbelliferous Family, Carro”; Parse-
ley, Lettuces, and Hemlock.---From the Solanum. Family,
Potatoes, Tomarta, Belladona.---From the Fung! Family,
Mushrooms. - - - - ------ - - , º,

*
CONVERSATION Se
CONVERSATION I.
EMILY.—As I wander over these beautiful mountains.
and observe the variety of flowers they produce, how much
I regret my ignorance of botany!
Mrs. B.-It is, certainly, a science particularly adapt-
ed to Switzerland; but why should you suffer your regret
to be vain To wish to learn is the first, and often the
most difficult step towards the acquisition of knowledge.
EMILY.—I should certainly like to understand botany,
but I have no wish to learn it: there is such a drudgery
of classification to encounter, before one can attain any
proficiency to recompense one’s labours, that I confess
I do not feel courage to make the attempt.
CARolf NE.-And, after all, what is it one acquires 7–
A knowledge of the class in which a flower is to be placed,
according to the number of its stamens or its pistils; and,
perhaps, after hard study, one may go so far as to ascer.
tain its Latin name, though you may still be ignorant
how it is called in your own vulgar tongue. Botany ap-
pears to me a science of rules and names, not of ideas;
and is, therefore, devoid of interest. I am, for my part,
quite contented to gather a sweet-sinelling nosegay of
beautiful garden monsters, as botanists denominate them,
without troubling myself about their scientific names.
Mes. B.-I will frankly own, that, for many years, I
entertained the same prejudices against botany, if such
you will allow me to call them ; but having had the good
fortune, during a spring I passed at Geneva, to hear a
course of lectures on that science by Professor De Can-
dolle, I was entirely converted; and I am fully persua-
2
14 INTRODUCTION.
ded that no natural science is dry, unless it be dryly
treated. If people will attend more to the frame than to
the picture which it contains, and if they will even cut
and disfigure the picture, in order to make it fit into the
frame they have prepared for it, no wonder that the sub-
ject should lose its interest.
EMILY.—None can be more likely to succeed in con-
verting others, than those who have been converted
themselves; and if you would indulge us, my dear Mrs.
B., with relating what you learnt at these lectures, I make
no doubt that Caroline would be tempted to listen to you,
were it but from curiosity to discover whether her first
opinions on the subject were correct, or whether she
ought not at least to acknowledge that they were hastily
formed.
CARolisE.—Oh, I shall be very thankful to be allowed
to remain, provided I am at liberty to depart if I find I
do not take an interest in the study.
MRs. B.-I shall not be ambitious of retaining unin-
terested listeners; and though I was delighted with the
instruction I received myself, I am very sensible that I
shall not be able to communicate to you either the same
degree of pleasure or of information. I will, however, do
my best to relate to you what I can recollect of these
lectures.
Mr. De Candolle, so far from confining himself to the
classification of plants, examines the vegetable kingdom
in its most comprehensive and philosophic point of view.
In describing the structure he investigates the habits and
properties of plants, and shows, not only how wonderfully
they have been formed to answer the purpose of their
own multiplication and preservation, but how admirably
they answer the higher purposes which nature has assign-
ed them, of ministering to the welfare of a superior order
of beings—the animal creation; and more especially to
that of man. IIe turns his attention particularly to point
out the means by which the science of botany can pro-
mote that with which it is most intimately and importantly
connected—agriculture. He prepares the soil and sows
the seed for the husbandman; he extracts the healing
INTRODUCTION. 15
Juices and the salutary poisons for the physician; he pre-
pares materials for the weaver, colours for the dyer; in
a word, as he proceeds there is scarcely an art on which
he does not confer some benefit, either by pointing out a
new truth, or warning against an ancient error. Thus,
throughout his course, his principal aim is to promote, b
his vast stock of knowledge, the welfare of his fellow.
Creatures,
ExIILY.—Treated in this point of view, botany cannot,
I think, fail to interest us.
MRs. B.-It is rather the physiology of botany which
I propose teaching you ; and I shall merely give you
such an insight into classification as is necessary to en-
able you to understand the structure and character of
plants.
Mr. De Candolle entered upon the subject by observ-
ing, that, in classing the various productions of Nature,
the first great line of demarcation is that which separates
the mineral kingdom from organised beings. How
would you make the distinction ?
CARoline.—Nothing more obvious : organised beings
have life, and minerals have not.
MRs. B.—Very true; yet I should be tempted to retort
upon you that this distinction is rather of names than of
ideas. I believe I have before observed to you, that we
know not what life is. We see its effects: they are suf.
ficiently apparent and numerous; and it is only by stu-
dying these effects that we are able to form any idea of
that state of being which we call life. The first distinc-
tion, therefore, to be made between minerals and beings
endowed with life is, that the latter are formed with or-
gans adapted to fulfil the several functions for which
they were destined by Nature. These organs differ, not
only in form and structure, but more or less in the mate-
rials of which they are composed : organised beings are
generally of a smooth surface, rounded, and irregular;
while minerals are rough, angular, and in their crystal-
line state of geometrical regularity.
One of the principal functions these organs have to
perform is nutrition. Unorganised matter may, in the
16 INTRODUCTION,
course of nature, be enlarged or diminished, either by
mechanical or chemical changes; minerals may be aug-
mented by the addition of similar particles, or by chemi-
cal combination with substances which are dissimilar,
but they have no power to convert them into their own
Inature.
Organised bodies, on the contrary, are increased in
size, by receiving internally particles of matter of a nature
different from their own, which they assimilate to their
own substance.
Exſily.—That is to say, that the food by which they
are nourished is converted into their own substance 1
MRs. B.-Yes; organised beings have also the power
of reproducing their species:—minerals may be broken
into fragments, but they are alike incapable of receiving
nourishment, of growing, or of reproducing.
Let us now proceed to inquire, what is the principal
distinction between the two classes of organised beings,
the animal and the vegetable creation.
CARoline.—Animals are endowed with a power of
loco-motion, while vegetables are attached to the soil.
MRs. B.-It would, perhaps, be more philosophical to
begin by ascertaining the cause whence this difference
arises. Animals are provided with a cavity called a
stomach, in which they deposit a store of food, whence
they are continually deriving nourishment. This organ
is essential to animals, as they are not constantly supplied
with food : they find it not always beneath their feet;
they must wander in search of it; and were they not fur-
mished with such a storehouse, in which to lay it up, they
would frequently be in danger of perishing.
ExILY.—Are we, then, in want of continual nourish-
ment? And should we dic if our stomachs were quite
empty?
MRs. B.-No, not immediately; for though the system
requires constant renovation, Nature is so careful of our
preservation, that she not only affords us the means of
subsistence, but provides resources in cases of accidental
interruption of the supply: after having consumed, ol
INTRODUCTION, 17
wº
rather, I should say, assimilated the food contained in the
stomach, the fat of animals is made to contribute to the
nourishment of their organs, and the support of life. In
some, such as the dormouse and the polar bear, this pro-
vision is carried to such an extent, that they pass several
of the winter months in a state of inanition; during which
period, the only sustenance their system receives is from
the abundant provision of fat which they had made during
the summer; and when they are roused from their lethar-
gy by the return of spring, they are lean and ravenous.
The food of animals is conveyed from the stomach to
the various parts of the body, by the function which is
ealled digestion. The food passes through small absorbent
vessels into the blood, and is thence circulated throughout
the system.
CARoline.—But, Mrs. B., one would think you were
going to give us the history of the animal rather than the
vegetable creation.
MRs. B.—Only so far as to enable me to point out the
distinction between them. p
Vegetables have no stomach; they do not require such
a magazine, since they find a regular supply of nourish-
ment at the extremity of their roots: with them, therefore,
there is no occasion for accumulation. In order to con-
ceive an idea of the form in which plants receive nourish-
ment, you must represent to yourself a very delicate
cobweb network, of such extreme tenuity as to render it
invisible until the interstices are filled and distended by
the nutriment lodged within them. The food of plants
is not, like that of animals, of a complicated nature ; but
consists of the simplest materials, water, and the solid
and gaseous matter contained within it.
The second distinction between the animal and vege-
table creation is, that the latter are not endowed with
sensibility.
ExIILY.—But the mimosa or sensitive plant, Mrs. B.,
when it shrinks from the touch, wears a strong appearance
of sensibility.
Mrs. B.-Yet I should doubt whether it is any thing
imore than appearance. Some ingenious experiments
2*
[8 INTRODUCTION,
have, indeed, been recently made, which tend to favour
the opinion that plants may be endowed with a species of
sensibility; and seem to render it not improbable that
there may exist in plants something corresponding with
the nervous system in animals.
CARoll NE.-The sensitive plant would then, no doubt,
be a nervous fine lady at the court of Flora. But, pray,
of what nature were these experiments 7
MRs. B.—There are certain vegetable poisons, such as
nux vomica, laurel-water, belladonna, hemlock, and seve-
ral others, which are known to destroy life in animals, not
by affecting the stomach, but merely by acting on the
nervous system. These poisons were severally adminis-
tered to different plants, either by watering them with, or
steeping their roots in, infusions of these poisons. The
universal effect was, to produce a sort of spasmodic action
in the leaves, which either shrunk or curled themselves
up; and, after exhibiting various symptoms of irritability
during a short time, became flaccid, and the plant in the
course of a few hours died.
EMILY.—I should have been curious to have seen an
experiment of this nature tried on the sensitive plant.
MRs. B.-It was done. Two or three drops of prussic
acid, which, you know, is a most powerful poison, were
poured upon a sensitive plant: the leaſlets closed and
opened again at the end of a quarter of an hour; but
they did not regain their sensitiveness for at least six or
eight hours. . When we see plants thus acted upon by
vegetable poisons, which are known to be incapable of
destroying the animal fibre, or of injuring the frame but
through the medium of the nerves, we may be led to sup-
pose, that certain organs may exist in plants with which
we are totally unacquainted, and which bear some analogy
to the nervous system in animals.
It is certain that plants possess a power of irritability
or contractibility; for it is by alternate contractions and
dilatations of the vessels, that they propel the juices which
rise within them. Here is a slip of elder: when I cut it
in two, the fluid continues oozing from both of the sepa-
rated parts; were there no action going on within the
INTRODUCTION, 19
stem, only a single drop would flow out at each orifice.
There are some ſlowers, such as those of the Barberry,
whose stamens will bend and fold over the pistil, if the
latter be pricked with a needle; and there is one instance
of a plant whose leaves move without any assignable
cause: this is the Hedysarum gyrans, which grows only
on the banks of the Ganges; it has three leaflets on each
foot-stalk, all of which are in constant irregular motion.
EMILY.—I recollect seeing a plant called Sundew (Dro-
sera,) the leaves of which, near the root, are covered
with bristles bedeved with a sticky juice. If a fly settles
on the upper surface of the leaf, it is at first detained by
this clammy liquid, and then the leaf closes, and holds it
fast till it dies.
Mrs. B.—The Diona’a muscipula affords another ex-
ample of the same kind ; it grows in the marshes of
South Carolina. Its irritability is so great, that an insect
which settles on it is generally crushed to death by the
collapsing of the two sides of the leaf, which, like that
of the Drosera, is armed with bristles.
CARoLINE.-But all plants are endued with some de-
gree of irritability, if you will not admit of sensibility;
for we know that, in general, their leaves turn towards
the light, and, when growing in a room, they spread out
their branches towards the windows, as if they were sen-
sible of the benefits they derived from light and air.
MRs. B.-Light and air conduce to their well-being,
and they are so wisely constructed by Providence as to
seek them; but it is independently of all choice or pre-
ference. We must consider plants as beings in which
the principle of life is reduced to its state of greatest
simplicity. As we advance in the scale of creation, we
find that the lowest animals are directed by instinct; in-
telligence increases as we approach towards man, who is
guided by reason: but the vegetable world is influenced
merely by physical causes, which derive their energy
from the principle of life.
EMILY.—But since plants are so inferior in the scale
of existence, why is their form so much more delicate
and beautifully varied than that of animals? Is it not
20 INTRODUCTION.
singular that Nature should be most solicitous for the ap-
pearance of her simplest works?
Mrs. B.-The most curious details of the structure of
a plant are visible in its outward form ; while those of
the animal economy are concealed in the anatomical
structure of the internal parts. The organs of plants are
ehiefly external, and are ornamental at the same time
that they perform the several functions for which they
were formed.
Plants appear, also, to be susceptible of contracting
habits: the mimosa, or sensitive plant, if conveyed in a
carriage, closes its leaves as soon as the carriage is in
motion, but after some time it becomes accustomed to it,
the contraction ceases, and the leaves expand; but if the
earriage stops for any length of time, and afterwards re-
eommences its motion, the plant again folds its leaves,
and it is time only which can reconcile it to its new situa-
tion.
EMILY.—This evinces strong symptoms of sensibility.
One would suppose that the plant was alarmed at the new
and unknown state of motion; and that its apprehension,
like that of an infant, returned every time the novelty
recurred.
MRs. B.-You will, perhaps, consider plants as patri-
otic, when you learn that those which are brought from
the southern hemisphere, faithful to the seasons of their
native country, make vain attempts to bud and blossoin
during our frosty winter, and seem to expect their sultry
Summer at Christmas.
CARo1.JNE.—If you continue thus, Mrs. B., you will
certainly make me think that plants are not wholly devoid
of sensibility.
Mrs. B.-We cannot positively deny it; but the evi-
dence against that opinion is so strong as to aimount al-
most to proof. Had Providence endowed plants with the
sensations of pleasure and of pain, he would, at the same
time, have afforded them the means of seeking the one
and of avoiding the other. Instinct is given to animals
for that express purpose, and reason to man; but a plant
rooted in the earth is a poor, patient, passive being: its
INTRODUCTION, 21
habits, is irritability, and its contractibility, all depending
on mere physical causes.
The properties of plants may be separated into two
classes: first, those which relate to their structure; such
as their elasticity, their hygrometric power: these proper-
ties may continue after death. Secondly, those which
relate to their vitality; such as contractibility: which,
consequently, can exist only in the living state.
The organs of vegetables are all composed of a mem-
branous tissue, which pervades the whole of the plant;
they are distinguished by the name of elementary, and
are of three kinds.
1st. The cellular system, consisting of a fine tissue of
minute cells or vesicles, of a hexagonal form, apparently
closed and separated by thin partitions, somewhat similar
to the construction of a honey-comb; or, bearing, per-
haps, a still nearer resemblance to the bubbles formed by
the froth of beer.
EMILY.—This appears very similar to the cellular sys.
tem in the animal economy, which you described to us in
our lessons on Chemistry.
MRs. B.-One of the chief purposes of the cellular
system in the animal frame is to contain the fat, a sub-
stance to which there is nothing analogous in the vegeta-
ble kingdom.
These cells in plants are marked by small spots, which
have been conjectured to be apertures through which fluids
are transmitted from one cell to another; but these marks
are so very minute, as to render it hazardous to venture
on deciding for what purpose they are designed.
CARoline.—If it is the cellular system which trans-
mits the sap, it should with more propriety be compared
to the veins and arteries of animals. But are not plants
furnished also with a vascular system?
Mrs. B.-Yes; and this forms the second set of ele-
mentarv organs. It consists of tubes open at both ends:
these are always situated internally, and are, besides,
guarded from injury by being lodged in a thick coating of
the cellular integument. Some of these vessels assume
the form of a necklace, their coats being at intervals
22 INTRODUCTION,
drawn tight together, or strangulated, so as to appear to
stop the passage of the fluid they contain.
CARolls E.-It is doubtless through the vascular sys-
tem that the sap rises?
Mrs. B.-The organs of plants are so extremely small,
that, though aided by the most powerful microscope, it is
frequently difficult to examine the structure of their parts
with a sufficient degree of accuracy to be able to ascertain
their functions. It has long been a disputed point,
whether the sap ascended through the vascular or the
cellular system of organs; but the latest opinion, and
that which Professor De Candolle is inclined to favour, is,
that it passes through neither; and that it rises through
interstices which separate the different cells.
ExILy.—Indeed . It seems to me very extraordinary
that the sap, which performs so essential a part in the
economy of vegetation, should not flow freely through
appropriate vessels, but be left to find its way as it can
between them.
MRs. B.-The sap, when first pumped up by the roots,
consists of little more than water, holding various crude
materials in solution ; it is, therefore, more important
that the regular organs should be reserved for its elabo-
ration, and its conveyance after that process, to the seve-
ral parts of the plant.
The third system of elementary organs is the tracheae;
so called from their conveying air both to and from the
plant: they are composed of very minute elastic spiral
tubes.
CARolisE.--But, surely, plants do not breathe, Mrs. B. ?
Mrs. B.-Not precisely in the same manner that we
do; but air is so essential an agent, both chemically and
mechanically, in promoting their nourishment and growth,
that it is scarcely less necessary to their existence than
to that of animals. Indeed, it is the opinion of Professor
De Candolle, that the function of transmitting air is not
confined to the tracheae, but extends to the whole of the
vascular system.
The whole of the vegetable kingdom consists of masses
of these several elementary organs, with the exception
INTRODUCTION. 23
of fungi, mosses, and lichens, whose vessels are all of a
cellular form ; they have no vascular system whatever.
Exily.—That affords a strong argument against the
passage of the sap through the vascular system.
MRs. B.-Certainly ; the fibres of plants are com.
posed of collections of these vessels and cells closely
connected together. The root and stem of plants consist
of such fibres : if you attempt to cut them transversely,
you meet with considerable resistance, as you must force
your way across the tubes, and break them; while, if
you slit the wood longitudinally, you separate the vessels
without breaking them, and have only to force your way
through the elongated cellular tissue which connects them.
ExIILY.—The difference is very observable; but I won-
der that the cells, being formed of a delicate membrane,
are not squeezed and crushed to pieces in the stems of
plants, especially when they become hard wood.
MRs. B.-The cells, by the growth of the stem, are
frequently drawn out of their original form, and elon-
gated; but the vascular system, which is of the greatest
importance, is internal, and lodged in a bed of cellular
integument, so that the pressure of the bark or surround-
ing parts is not sufficient to crush it.
The layers of wood which you may have noticed in
the stem or branch of a tree cut transversely, consist of
different zones of fibres, each the produce of one year's
growth, and separated by a coat of elongated cellular tis-
Bue, without which you could not well distinguish them.
The cuticle, which is the external skin or covering of
the plant, consists of an expansion of the cellular tissue ;
and is furnished with pores for evaporation.
CARoll NE.-This is, I suppose, neither more nor less
than what is commonly called the bark?
Mrs. B.-On the contrary, it is both more and less than
the bark. More, because the cuticle is extended over
every part of the plant; it covers the leaves and flowers,
with the exception of the pistil and anthers, as well as
the stem and branches; less, because the bark consists
of three distinct coats, of which the cuticle forms only
that which is external. The cuticle of a young shoot,
24 INTRODUCTION,
after it has been for some time exposed to the atmo.
sphere, becomes opaque, dries, and distended by the late-
ral growth of the branch, splits, and after a year or two
falls off. A second membrane is then formed by the de-
siccation of the external part of the cellular integument;
but it differs from the former in being thicker, and of a
eloser texture. It is not furnished with pores, having no
other function to perform than to enclose a layer of air,
and preserve the internal parts from injury. This enve-
lope is distinguished from the former by the name of epi-
dermis.
These general, thqugh, perhaps, rather desultory ob-
servations will, I hope, prepare you for our next interview ;
when I propose to take a full-grown plant, examine its
structure, and explain the nature of those organs by
which it is nourished and preserved. We shall begin
with the roots, and then proceed up the stem to the
leaves.
EMILY.—I should have expected that you would have
commenced by the birth of the plant, that is to say, the
germination of the seed.
Mrs. B.-If the plant derives life from the seed, the
seed equally owes its origin to the parent plant; and as
the preparation of the seed, by that beautiful and delicate
system of organs, the flower, is one of the most curious
and complicated operations of the vegetable economy, I
think it more eligible to reserve it for the latter part of
our studies.
CARo11NE.—That is very true so far as regards the
formation of the seed; but its bursting, and the sprout-
ing of the young plant, appears to be the natural com-
mencement of the history of vegetation.
MRs. B.-The germination of the seed is a process so
intimately connected with its formation and composition,
that it is a reciprocal advantage to treat of them together,
or, rather, in immediate succession, instead of separating
them by the intervention of the whole history of vegeta.
tion.
CONVERSATION II.”
F.
25
ON ROOTS,
MRs. B.-We are now to examine the structure of
those organs, whose office it is to nourish and preserve
the plant. * , e.
In the nutrition of plants, six periods are to be distin-
guished :—
1. The absorption of nourishment by the roots.
2. The transmission of nourishment from the roots to
the different parts of the plant.
3. The developement of the nourishment.
4. The action of the air on plants.
5. The conversion of nourishment into returning sap
or cambium.
6. The secretion of various juices from the Sap.
Plants being deprived of locomotion, as we have ob-
served, cannot go in search of food : it is necessary,
therefore, that nature should provide it for them in their
immediate vicinity. Those simple elements, which are
almost every where to be met with, water and air, consti-
tute this food. Water not only forms the principal part
of it, but serves, also, as a vehicle to convey what solid
food the plant requires; and as a vegetable is unfurnished
cither with a mouth to masticate, or a stomach to digest,
solid food can be received only when dissolved in water.
In this state it is absorbed by the roots; for the root not
only supports the plant by fixing it in the soil, but affords
a channel for the conveyance of nourishment. If it does
not fulfil this double office, it is not a root, but a subter-
raneous branch.
CARoll NE.-But will not a branch, if placed under
ground, become a root, and absorb nourishment? I have
seen the gardener fasten down branches of laurel and
other shrubs, leaving only the extremity above ground;
and these layers strike root, and become, in the course
of time, separate plants.
MRs. B.-Striking root implies, that roots will (under
certain circumstances) grow from a branch, but the
branch itself cannot be converted into a root; for at the
3
26 ON R ſho'I'S.
extremity of each fibre of a root, there is an expansion
of the cellular integument called a spongiole, from its re-
semblance to a small sponge, being full of pores, by
means of which the roots absorb the water from the soil.
Now, a branch, being destitute of this apparatus, cannot
supply the plant with nourishment.
CARolrxE.—True : it cannot feed without a mouth ;-
but I thought that there were pores in every part of a
plant.
MRs. B.-The pores in those parts of a plant above
ground are almost wholly for the purpose of exhalation.
The roots have no pores except in the spongioles at their
extremities, which, as I have observed, are for the purpose
of absorption. It would be very useless for them to be
furnished with evaporating pores, since they are not ex-
posed to the atmosphere, where alone evaporation could
take place.
EMILY.—The tendrils of vines, then, and of other
climbing plants, which serve to fix them against a wall,
or the trunk of a tree, cannot be considered as roots;
since, although they answer the purpose of sustaining the
plant, they are unable to supply it with nourishment.
MRs. B.—Certainly, these plants are furnished with
roots which pump up nourishment from the soil; but
there are some parasitical plants, such at the Wiscum
album or misletoe, and the Epidendron Vanilla, which,
having no immediate communication with the earth,
strike their fibres into the stems or branches of a tree,
and derive their nourishment from this richly-prepared
soil; but as the absorption in this case is not carried on
by the regular mode of spongioles, these fibres are not
denominated roots.
A root is never green, even when exposed to the light,
an element which is essential to the developement of the
green colour in other parts of the plant.
The root, then, by means of the little spongioles at-
tached to its extremities, sucks up whatever liquid comes
within its reach; in proportion as it grows, its fibres
spread themselves over a greater extent of soil, and come
in contact with a greater quantity of moisture; and the
ON ROOTS. 27
plant, whose branches extend above ground, in propor-
tion as the root spreads beneath, requires a more abun-
dant supply of food.
EMILY.—And do the roots take up every kind of liquid.
or have they any means of selecting what is suited for
their nourishment 7
CARoline.—How would it be possible for them to
make a choice, having neither reason nor instinct to di-
rect them 1 For I conclude that the little spongioles are
not endowed with the sense of taste, to enable them to
discriminate between different sorts of food.
ExIILY.—True ; but without endowing the vegetable
creation with reason, instinct, or even sensibility, Nature
might possibly have so constructed the absorbent pores,
that, either by mechanical or chemical means they should
reject what was unfit, and receive only what was good for
the plant.
MRs. B.-The only provision which Nature appears to
have made with this view, is, to have formed the pores of
the spongioles of such small dimensions, that they are in-
capable of absorbing a liquid which is thick or glutinous ;
for if the fluid be loaded with particles not extremely mi-
nute, they cannot pass through the tubes which compose
the vascular system of the plant. I do not mean to say
that these pores have any power to reject a dense or
viscous fluid, but that they will be clogged and obstructed
by it, and the absorption consequently cease.
Water which has flowed through the manure of a farm.
yard, and abounds with nutritive particles, is much used
on the Continent for watering gardens; yet, unless copi-
ously diluted with pure water, it is found to be deleterious,
choking the plant with an excess of food. But when the
liquid is sufficiently limpid, the spongioles suck it up with
equal avidity, whether it contain salubrious nourishment
or deadly poison.
EMILY.—Oh, my poor plants! Why did not Nature
grant them some means of preservation from such dan-
gers ?
WRs. B.-Nature has bountifully diffused throughout
28 ON ROOTS.
the soil such fluids as are adapted for the nourishment of
the vegetable creation: no streams of poison flow within
their reach. It is unnecessary, therefore, to guard
against a danger which does not exist. It is merely from
the experiments of the chemist and the physiologist that
we learn that the roots of plants will absorb liquids, of
whatéver nature, presented to them, provided they be
sufficiently limpid. The spongioles act only by capillary
attraction, and suck up moisture just as a lump of sugar
absorbes the water into which it is dipped. As a proof
of this it has been shown, that if roots, saturated with
moisture, be transplanted into very dry earth, the latter
will absorb the moisture from the roots.
EMILY.–If so, why do not the roots continue to absorb
moisture when the plants are dead, as well as when they
are living. A sponge, or a lump of sugar, have no vital
principle to stimulate them to draw up liquids !
MRs. B.-Neither does absorption immediately cease
upon the death of a plant, as the blood ceases to circu-
late upon the expiration of animal life; but when the ves.
sels through which the fluid should pass have lost their
vital energy, that susceptibility of irritation and of con-
traction, which enabled them to propel the fluid upwards,
ceases, and it can no longer ascend into the roots, but
remains stagnant in the spongioles, which soon become
saturated. Disease and putrefaction follow ; and that
nourishment, which was designed to sustain life, now
serves only to accelerate disorganisation. The fluid is,
however, still performing the part assigned to it by Na-
ture; for if it be necessary to supply living plants with
food, it is also necessary to destroy those which have
ceased to live, in order that the earth may not be encum-
bered with bodies become useless, and that their disor-
ganised particles may contribute to the growth of living
plants. Thus the putrefaction of dead leaves, straw, &c.
which reduces these bodies to their simple elements, pre-
pares them to become once more component parts of
living plants.
CARolix.E.—What a beautiful provision for the vegeta-
ble economy I know not whether you call this botany,
ON ROOTS, 29
Mrs. B. ; but it is totally different from the dry classifica-
tion of flowers. It elevates the heart while it enlightens
the mind, and bears more resemblance to lessons of mo-
rality and religion than to botany.
MRs. B.—The physiology of plants, of which we are
now treating, forms one branch of the science of botany,
and one which is certainly replete with interest; but from
every natural science, and every branch of it, from the
arrangement and classification of the organs of the flower
as well as from the history of vegetation, the well-dispo-
sed mind will draw lessons of piety; and he must study
Nature with very contracted views, who does not raise
his thoughts from the admiration of the creation to that
of its all-wise and beneficent Creator. But to return to
our subject.
Botanists distinguish several kinds of roots. The Ra-
dir fibrosa, or fibrous root, is the most common and most
simple in its form : it consists of a collection or bundle of
fibres, connected by a common head, and often merely
by the base of the stem. The roots of many grasses and
most annual herbs are of this description ; during their
short existence, which is limited to one summer, they
continue growing, both by forming new fibres and by
elongating the old ones. These fibres are occasionally
covered with a sort of shaggy down, which, as it gene-
rally occurs in loose or sandy soils, is considered as a
provision of Nature for the purpose of fixing the plant
more firmly in the ground.
EMILY.—Of what description are the roots of those
weeds, such as couch-grass, which seem to be intermin-
able 1 If you attempt to eradicate them, you meet with a
succession of bunches of fibres springing from a root
which grows horizontally, and appears to be endless.
MRs. B.-This is the radir repens, or creeping root.
The long horizontal fibre is, in fact, not a root but a sub-
terraneous branch, for it has no spongioles: the real
roots are the simall bunches of fibres which spring from
it. Such a root is very tenacious of life, as any portion
in which there is an articulation will grow ; it decays at
its origin, and continues gºing at its extremity.
&
J0 ON ROOTS.
EMILY.—Then we must not seek for its origin, but its
extremity, in order to eradicate it.
Mrs. B.-You cannot destroy it without digging up the
whole of the subterranean stem: it is this which renders
it so difficult to eradicate.
CARolin E.—Yet surely not more difficult than the Ox-
eye, and many other weeds, whose strong penetrating
roots seem to strike to the very centre of the earth ; for,
however loosened by digging, they are scarcely ever
pulled up entire.
MRs. B.—The root of these plants is called fusiform,
or spindle-shaped. It is also called the tap root, from its
tapering so considerably towards the end ; and the pivot-
root, owing to its fixing the plant so immoveably in the
carth. This root is but scantily provided with the means
of acquiring food, having sometimes not more than a
single fibre furnished with a spongiole at its extremity.
To compensate for this disadvantage, the root is of so
moist and fleshy a nature as to afford an ample store of
provision.
CARoll NE.-But with such limited means of suction.
how can this magazine be replenished 1
Mrs. B.-The surface of the ground immediately ex-
posed to the drying powers of the sun and wind, retains
less moisture than the deeper and more sheltered strata of
the soil; besides, the store is laid up during the season
of abundance, and measured out, as the necessities of the
plant require, during that of dearth. Here, you see, are
a variety of compensations for its circumscribed power of
absorption.
A very simple experiment will convince you, that the
spindle-shaped root, as well as those of every other de-
scription, absorb water only by the spongioles at their ex-
tremities. If you immerse a young radish in a glass of
water, so that every part of it shall be covered except the
taper end of the root, you will find that it will soon die:
while, if you immerse only the extremity of another ra.
dish in water, you will preserve it alive. The whole
body of the root serves to fix and support the plant in
the soil, but it is the extremity alone which absorbs
nourishment.
ON ROOTs. 31
It sometimes happens that this species of root, whether
from want of vigour or some mechanical impediment, is
checked in its growth, and wears the appearance of being
cut or bitten off. It has hence obtained the name of radia
praemorsa, or abrupt root; but it is, in fact, nothing more
than the radir fusiformis originally mutilated, and modifi.
cd by that mutilation in successive generations.
EMILY.—Is not the Devil's bit Scabious of this descrip-
tion ? I recollect hearing a curious story of its acquiring
this mutilated form. In the age of sorcery and credulity
it was affirmed, that the devil, out of spite to mankind, bit
off the end of a plant which was endowed with so many
excellent properties.
MRs. B.-The name of the plant is, no doubt, derived
from this ridiculous story; but I should be rather inclined
to suppose that it was an allegorical compliment to the
virtues of the plant, than that such absurdity could gain
belief in any age.
EMILY.—Bulbous roots, such as those of the hyacinth.
the lily, and the onion, are also solitary roots, Mrs. B. ;
but they seem to fix the plant in the soil rather from their
mass than their depth, for they are very superficial; and
it is, no doubt, from the difficulty of finding water, that
Nature has added to their root a tuft of small stringy filres
(which are doubtless furnished with spongioles) to multi-
ply the points of absorption.
MRS. B.—The bulbous root, radir bulbosa, is improperly
so called, for the tufts or fibres pendant from the bulb are
ulone the roots. The bulb itself, you will learn, when
you come to examine its structure, constitutes the stem of
the plant; no wonder, therefore, that it is superficial.
Exſily.—How curious! a globular subterraneous stem
MRs. B.-If you prefer giving it the name of bud rather
than of stem, you may, with equal propriety, for it con-
tains the whole embryo plant; but, as we are not at pre-
sent treating the subject either of stems or of buds, we
must reserve this explanation for a more appropriate
period.
Qarolixe–And are the roots of potatoes of this de-
scription
32 ON ROOTS,
MRs. B.-The potatoe belongs to the class of tuberous
or knotted roots, radir tuberosa, which are of various
kinds, comprehending all such as have fleshy knobs or
tumours. This sort of root belongs to perennial plants,
though the knobs are frequently either annual or biennial.
In all cases, they are to be considered as reservoirs of
nourishment, which enable the plant to support the ca-
sual privations of a barren or dry soil.
Some plants, of which Timothy-grass is an instance
acquire tumours when situated in a soil subject to vicissi-
tudes of drought and humidity, and lose them if trans-
planted to one regularly supplied with moisture.
EMILY.—It is wonderful to observe in what an admira-
ble manner roots find means of compensation for local
inconveniences !
MRs. B.-The potatoe is a species of mucilaginous,
farinaceous excrescence, growing upon subterraneous
branches, which have no means of deriving nourishment
from the soil; and it is very remarkable, that this salu-
brious and nutritious substance grows on a plant, the real
fruit of which is of a poisonous nature.
The object of nature throughout all these varying forms,
is the same—to establish a reservoir, in which the vital
force of the plant, and its material resources are hus-
banded.
The root of the orchis is well deserving our notice from
its singularity. It consists of two lobes, somewhat simi-
lar to the two parts into which a bean is divided. One of
these perishes every year, and another shoots up on the
opposite side of the remaining lobe. The stem rises
every spring from between the two lobes, and, since the
new lobe does not occupy the same place as its prede-
cessor, the orchis every year moves onwards, though to
the distance only of a few lines.
CARoline.—Thus, in the course of a certain number
of years, the orchis may make the tour of a garden, pro-
vided the gardener does not interrupt it in its progress.
MRs. B.-There are some plants which, like the Indian
fig-tree, shoot out roots from the stem many feet above
ground: they grow downwards, bury themselves in the
ON ROOTs. 33
Soil, and new stems ultimately spring up from them;
but the epidermis of these roots are never green, like that
of young branches.
EMILY.—I recollect reading an account of a tree which
bears some analogy to this fig-tree. It was situated at
the top of a high wall, and its roots grew down the side
of the wall till they reached the ground, a distance of
about ten feet, and then buried themselves in the soil.
MRs. B.-This account is given by Lord Kalmes of a
plane-tree, situated among the ruins of the New Abbey
monastery in Galloway. But the analogy with the fig-tree
is only apparent, this singular growth of the roots being
merely the result of local inconvenience.
CARolix E.-I once heard of a curious experiment per-
formed on a willow-tree. It was dug up, and reversed.
the head of the tree was planted in the ground, and the
roots, which were now uppermost, stretched out like naked
branches in the air. In the course of time, the roots were
transformed into branches, and the branches into roots.
But how could the latter acquire spongioles.
MRs. B.-They did not; but roots sprouted from the
subterranean branches, and branches shot from the unlu-
ried roots. This is, however, an adventurous experiment.
which does not often succeed.
The duration of roots is either annual, biennial, or pe-
rennial. To the first belong plants whose existence is
limited to one summer, such as barley, and a vast num-
ber of garden and field flowers. The biennial root pro-
duces the first season only herbage, and the following
summer flowers and fruit, or seed; after which it perishes.
The perennial belong to plants which live to an indefinite
period, such as trees and shrubs.
A root consists of a collection of fibres composed of
vascular and cellular tissue, but without tracheae or ves-
sels destined for the transmission of air ; but there is so
great an analogy between the structure of the root and
that of the stem, that I shall reserve what observations 1
have to make on this subject till our next meeting, when
| propose to examine the nature of the stem,
34
CONVERSATION III.
( ON STEMS,
Mrs. B.-Every plant has a stem.
CARoll NE.-That is to say, trees and shrubs; for
there are many plants, such as violets, anemones, fern,
and a variety of others, which have large bunches of
leaves growing from the roots out of the ground: the
flowers, it is true, have each a stem, but the plant itself
seems to have none.
Mas. B.-I must repeat my assertion :-every plant
has a stem, through which the sap circulates, and from
which the leaves and flowers spring. This stem, it is
true, is not always apparent: it is sometimes concealed
under ground, sometimes disguised under an extraordi-
nary form. The stem of the tulip is contained within
the bulb or onion, which is commonly, but improperly,
called its root; that of the fern is subterraneous. A ve
curious plant grows in some of the vallies of the Alps,
called willow-grass (saule en herbe.) You sometimes
meet with a plain covered with it, and you would not
imagine whence it derives its origin: it is nothing less
than the head, or rather, I should say, the extremities, of
the branches of a large willow-tree.
EMILY.—Do you mean a tree which has been acci-
ilentally overthrown and buried, the leaves of which
have sprouted above ground !
Mrs. B.-No; it is a willow which is annually buried
alive. Every spring it struggles to rise above ground,
and every autumn it disappears beneath the soil. Let us
suppose the seed of a willow springing up at the foot
of a mountain, and that the earth which is annually
carried down by the rains from this mountain should be
sufficient to bury the young plant. The following spring
it would again shoot out with redoubled vigour; for the
growth of the plant having been checked by the fall of
the soil, the sap, which should have been expended in the
produce of foliage, being accumulated in the little stem.
will be sufficient to afford nourishment for a double shoot :
ON STEMs. 35
two little branches will therefore now appear. This, like
its predecessor, flourishes but for a season, and is buried.
The two stems the following spring produce four, which
expand their leaves, and in the autumn are consigned to
the earth; the third year eight stems arise ; the fourth,
sixteen; and the plant goes on thus doubling its sprouts
every year, and the surface of the soil rising, till at
length a plain is formed covered with verdure, consisting
of the leaves of the willow-tree.
CARoLINE.—What a singular growth !—How much I
should like to walk on one of these curious meadows!
MRs. B.-They are, as you may suppose, not very
common, since it requires peculiar local circumstances to
produce one : the vicinity of a mountain which shall
annually send down earth sufficient to bury the young
shoots, but not so deeply as to prevent their rising from
their tomb every spring. The age of these willows has
been ascertained by digging down the side of the plain and
observing how often the shoots have been renewed; the
lower you descend, the more you find the branches in-
crease in size and diminish in number, till at length you
reach the original and single stem.
CARolixE.—But what is the difference between a sub-
terraneous stem and root ?
Mrs. B.-The structure of the root and of the stem is
in some respects different, and their functions totally so :
the former merely sucks up nourishment from the soil and
transmits it to the leaves; the latter is supplied with or-
gans to distribute it, variously modified, to the several
parts of the plant, the leaves, the flowers, &c.
There is a point or spot separating the stem from the
root, called the neck, which may be considered as the
seat of vitality. If you cut off the root of a young
plant, it will shoot out afresh ; if you cut away the stem,
it will be renovated ; but if you injure this vital spot, the
plant will infallibly perish.
EMILY.—I think it should be called the heart rather
than the neck of the plant, since it is so essential to its
ſºxistence.
CARo11NE.—ls not the neck equally so? Animals
will not survive decapitation any more than plants. But
it is true the situation of the neck does not quite cor-
respond with that of the animal frame, unless you deno-
minate the roots the body of the plant, and the whole that
is above ground the head.
MRs. B.—I do not think the huge trunk of a venerable
oak would yield that title to its roots, and the extremity
of its branches crowned with verdure would lay exclusive
claim to the dignity of head.
The stems of plants are divided into two classes:
those which grow internally, and those which grow exter-
nally. M. De Candolle distinguishes them by the cha-
racteristic appellations of endogenous and exogenous, a
distinction first introduced by a celebrated French bota-
mist, M. Desfontaines. We have no corresponding terms
in English: in our country these two classes of plants
retain the denomination given them by Linnaeus, of mo-
nocotyledons and dicotyledons.
CARolin E.-These are hard-sounding names, Mrs.
B.: I hope their explanation will render them intelligible.
Mrs. B.—I believe you will find no difficulty in under-
standing them. The class of plants whose stems grow
internally, and are by us denominated monocotyledons,
are distinguished by their seed, which, during germina-
tion, is converted into a thick leaf, yielding nourishment
to the young plant until it is strong enough to suck it up
from the soil. This leaf is called a cotyledon, and the
epithet mono, which signifies one, implies that this class of
plants have a single cotyledon.
The other class, whose stems grow externally, and are
called dicotyledons, comprehends all those plants whose
seeds in germinating split into two parts, forming two
nutritive lobes or senminal leaves; and hence they bear
the name of dicotyledons, which signifies two cotyledons.
Exiily.—I have seen lupins, peas, and beans germi-
mate in this way; but do not recollect having observed
any seed germinate with only one cotyledon.
MRs. B.—They are much less common in these cli-
mates, at least in plants of sufficiently large dimensions
for their cotyledons to be observable.
ON STEMS. 37
There is a third class, denominated acotyledons, which
have no cotyledons and no vascular system, such as
fungi, lichens, &c.; but of these we shall not treat at
present.
Let us first examine the structure of the stems of the
monocotyledons or endogenous plants. Of this descrip-
tion are the date, the palm, and the cocoa-nut tree, the
sugar-cane, and most of the trees of tropical climates.
Their stems are cylindrical, being of the same thick-
ness from the top to the bottom; while those of Europe.
you know, always become more slender and taper to:
wards the summit of the tree, approximating to the coni-
cal form.
CaRoline.—I thought that endogenous plants were
those which grew in our own country, in opposition to
exotics, or plants of foreign countries; but, by your ac-
count, it is just the reverse, for endogenous plants grow
in countries most distant from us.
MRs. B.-You confound the word cndogenous with in-
digenous : the latter signifies to grow within the country;
the former is a French word, not yet introduced into the
English language, signifying to grow internally, or within
itself.
CARolin E.-Within itself! How can the stem increase
in size internally 7 One would think that the new layers
of wood growing in the interior part of the stem would
burst the external coats.
MRS. B.-The more the external coats are pressed by
the new growing wood, the closer and more compact they
become, and the greater the resistance they offer to the
internal layers; till at length a period arrives when the
outer coats are so hardened and distended as to yield no
longer: the stem has then attained its full growth in ho-
rizontal dimensions, and offers a broad flat circular sur-
face to view, which has scarcely risen in height above
the level of the ground.
EMILY.—How singular a mode of growing ! In this
first stage it must resemble the stump of the trunk of a
tree which has been cut down; but how does it grow up
afterwards
4
J8 ON STEMS,
Mrs. B.-The following spring, there being no room
for a new layer of wood to extend itself horizontally, it
shoots up from the centre of the stem vertically; fresh
layers every year successively perforate this central
shoot, till, from the innermost, it becomes the outermost
layer of wood ; hard, compact, and of the same horizon-
tal dimensions as the base : the second period of growth
is then completed; and thus the stem continues growing,
for a certain number of years, horizontally, and then takes
a sudden start upwards.
EMILY.—The stem then does not begin to rise until it
is as large in circumference as at full growth. How I
should like to see one of these broad flat stems :
MRs. B.-You may see them growing in hothouses;
and though we have none in the open air in these climates,
we have many smaller plants of the same description.
Corn and all gramineous plants, the liliaceous tribe of
flowers and bulbous roots, are all endogenous.
CARoll NE.-But lilies, tulips, and all flowers which
spring from bulbous roots have long stems, thick at the
lower end, and tapering towards the flower.
MRs. B.-You again confound the stalk of the flower
with the general stem of the plant. Both flowers and
leaves, with but few exceptions, have each a separate
stem or foot-stalk: that of the flower is called by bota-
mists a peduncle, or pedicel; that of leaves a petiole.
These are perfectly distinct from, and independent of, the
general stem of the plant. The stems of bulbous plants
are contained within the bulbs as I have already informed
you.
CARolin E.-This mode of growing puts me in mind
of the pushing out of an opera glass, the sliding cylinders
of which are contained one within the other.
MRs. B.—The leaves and fruit of this class of plants
grow from the centre of the last shoot, and form a sort
of cabbage at the top of the tree, which, if you cut off,
the tree perishes.
EMILY.—But what becomes of the bark of these trees?
How does that resist the pressure of so many successive
layers of wood?
ON STEMIS. 39
Mins. B.--Endogenous plants have no real bark, the
external coats of wood are so much hardened as to ren-
der such a preservation unnecessary.
ExIILY.—But the palm and cocoa-nut tree, which I
have seen at Mr. Loddiges' hothouse, have a very rough
external coat, greatly resembling bark.
Mrs. B.-This is formed of the basis of decayed
leaves. A circle of leaves annually sprouts from the rim
of the new layer of wood; and, when they fall in au-
tumn, leave these traces of their past existence. When
a European woodcutter begins to fell a tree of this de-
scription, he is quite astonished at its hardness. “If I
have so much difficulty with the outside,” says he, “how
shall I ever get through the heart of the wood” But as
he proceeds, he discovers that the trees of the tropical
clines have tender hearts, if you will allow me the ex-
pression; this circumstance renders it very easy to per-
forate them, and makes them peculiarly appropriate for
masts of vessels, pipes for the conveyance of water, and
such like purposes.
These plants have usually no branches; but there is
one species of palm-tree which shoots out two or three
branches together.
The family of the gramineous plants, that is to say,
the grasses and corn have a knot at the base of each
leaf, whence the shoot grows.
CARolix E.-I have observed that the straw of corn is
hollow, but closed at certain intervals, forming externally
a sort of ring; and it is from these rings that the leaves
and branches shoot.
MRs. B.—The sugar-cane, which grows in this man-
ner, is the largest of the gramineous plants.
Lilies are also of this description.
The Yucca of the tropics differs from our liliaceous
plants only by having a longer stem; in these temperate
climes vegetation has not sufficient vigour to develope all
the energies of the plant, and the stem grows only late-
rally, never shoots upwards, but lies concealed in the
bulb., Were it transplanted to a tropical climate, as soon
as it had attained its lateral growth, it would shoot up-
wards in the manner I have described.
40 ON STEMIS.
The structure of erogenous plants or dicotyledons, tº
which the trees of our temperate climes belong, is much
more complicated. Here, then, are two reasons for our
submitting them to a more accurate investigation.
The stem is composed of two separate parts: the one
ligneous, the other cortical ; in other words, it is formed
of wood and bark.
The wood consists in the first place of the pith, a soft
medullary substance, which occupies the centre of the
stem, and is almost always of a cylindrical form. This
soft pulpy body does not grow or increase in size with
the tree, but retains the saine dimensions it originally had
in the young stem.
CARoll SE.-I thought that it rather diminished; for if
you cut a young branch or stem, the growth of one sea-
son, the pith is very considerable, while little or none is
to be discovered in the trunk of a full grown tree.
Mrs. B.-The pith which fills the shoot of one season
is scarcely perceptible in a large tree ; the quantity,
however, remains the same. Its dimensions may be con-
tracted by the pressure of the surrounding coats of wood,
which sometimes so condenses and hardens it as to pre-
vent its being distinguished from them.
Some trees have a much greater quantity of pith than
others; the elder-tree, for instance, abounds with it.
The quantity of pith in the branches depends also upon
their nature: if the branch is barren, it contains much
more than if it is destined to bear fruit, but in the same
individual stem or branch the quantity never alters.
The pith consists of cellular tissue. If this membrane
be of a very fine texture, it is susceptible of extension as
the branch lengthens; but if it be coarse, and the cells
large, when the branch grows, it cracks and separates
into parts. This is distinctly visible in a branch of jessa-
mine, if you slit it open so as to exhibit the pith.
CARo1.1NE.—Here is one which we may examine. I
will slit it longitudinally : look, Emily, the pith is sepa-
rated into parts, as if it had been forcibly torn asunder.
MRs. B.-It is the growth of the stem which thus rends
the pith in pieces.
ON STEMIS. 41
l EMILY.—Then is it not destroyed and rendered use-
ess 7
Mrs. B.-Yes;- but not until it has fulfilled the purpose
of its destination, which is to nourish the young w
during the first period of its existence.
EMILY.—It acts the part of a cotyledon or nurse to
the young wood. But when it is become dry, what is to
perform this office to the new wood which is annually
formed !
Mrs. B.—Every new layer of wood is lined with a
layer of cellular tissue, which may be considered as the
pith of the wood to which it is attached. These internal
coatings not only separate the several layers of wood, but
are also interwoven and incorporated with them, and may
be seen in the form of rays, which appear to issue from

the central pith, and proceed to the external layer of
wood : these are called medullary rays; they are visible
in wood, but are remarkably distinct in the root of the
carrot.
CARolrxE.—But these fibres or rays, which appear all
to proceed from the centre, cannot be continuous, since
they originate annually in each fresh growth of wood.
MRs. B.-Very true; but they are so minute and so
numerous, that the termination of those of one year's
growth, and the commencement of those of the following
year, cannot be distinguished. This gives them the ap.
pearance of being continuous; but were it really so, their
distance from each other would increase in proportion as
they diverged from the centre; yet you see in the carrot
they are as close, and consequently much more numerous,
in the external layers of wood, than in those nearer the
central part. In one sense, indeed, they may be con-
sidered as continuous; as it is conjectured that the growth
of the new wood originates from the extremities of the
medullary fibres of the preceding year: this would tend
to give regularity to the distribution and direction of the
successive rays, and an appearance of continuity. A
succession of these horizontal rays, perfectly regular,
form vertical planes along the stem, which may be tole.
4*
42 ON STEMS.
rably well represented by those circular brushes whicle
are made to clean the inside of bottles.
ExIILY.—The wood of exogenous plants, growing exter-
nally, has not the same difficulties to encounter as that
of endogenous plants.
MRs. B.—The difficulty is rather reversed than di-
minished, the pressure being from the external upon the
internal parts. . The first layer surrounding the central
pith grows freely during a twelve month, but the follow-
ing year it is enclosed by a new layer; and notwith-
standing the accession of nourishment it receives from the
roots, and the additional space it would, if unconfined,
occupy, it is pressed and squeezed by the new layer into
a narrower compass than it occupied the preceding year.
In this distressing situation, what is to be done 3 Com-
pelled to yield laterally, it makes its way where there is
no pressure; that is to say, vertically: thus the stem
grows in height at the same time that it increases in
thickness. The first layer of wood having, therefore,
found a vent for that new portion of its substance which
could not be contained in the contracted space in which
it was confined by the growth of the second layer, this
portion grows freely during the second year; when a
third layer shooting up around and compressing the se-
cond, this in its turn escapes from bondage, but, rising
vertically, it encloses and confines the first layer.
CARoll NE.-The second layer from the prisoner be-
comes the gaoler; but its prisoner does not excite my
commiseration, for the first layer, having learnt how to
escape, doubtless profits by its experience, and rises above
the fetters with which it is encircled.
MRs. B.-Yes; the first layer thus makes a shoot up-
wards every year, and the new layers follow its course in
regular succession. This mode of growing, you must
observe, renders the form of the stem conical, the number
of layers diminishing as the stem rises.
These layers of wood attain a state of maturity, when
they become so hard by continued pressure as to be no
longer susceptible of yielding to it. Previous to this pe.
riod, the layers bear the name of alburnum, signifying
ON STEMS, 43
white wood, for wood is always white until it reaches this
degree of consistence. The length of time requisite to
attain a state of maturity varies extremely, according to
the nature of the wood. In some trees five years are
sufficient for this purpose; in others ten or twenty are
necessary; and the Phyllyrea requires no less a term
than fifty years to convert its alburnum into perfect
wood. When once the first layer has attained this point
of maturity, the others naturally follow in succession,
according to their respective ages.
ExIILY.—But are those dark-coloured woods, such as
mahogany and rose-wood, ever white 1
MRs. B.-Yes; and, what is still more remarkable,
ebony, a wood which is completely black, is white until
it has attained this state of maturity. Here is a small
piece of a branch of ebony cut transversely : you see
that the interior parts are perfectly black, and are sur-
rounded by a ring of white wood or alburnum. The dif.
ference between the alburnum and perfect wood is less
marked in woods of a lighter colour, but it is always suf.
ficiently so to be distinguishable. Look at this trunk of
chesnut-tree, which has been recently cut down with a
SaW.
CARolisE.—I not only see plainly where the perfect
wood is separated from the alburnum, but I can distin-
guish every layer of wood. I follow them in imagination
in their successive shoots upwards to extricate themselves
from the pressure of the new layers, by counting the
number of layers at the base of the tree; then, Mrs. B.,
shall I be able to ascertain its age 1
MRs. B.-Yes; and you may do more : for if you take
the trouble to count the number of layers at each end of
one of those pieces of wood which have been sawed into
logs for fuel, you will learn how many years that portion
of the tree was in growing.
Exily.—There are thirty layers at one end, and twenty
at the other; consequently the tree must have been ten
years growing the length of this log. I little thought 1
sº ever have taken so much interest in a log of fire-
WQ( )(I -
44 ON STEMS.
MRs. B.-However mean or common-place may be
the purposes to which we apply the works of Nature,
when studied in a philosophical point of view, they are
no less objects of interest and admiration.
The annual layers of wood are distinguishable not only
by their different degrees of hardness and density, but
also by their being separated by layers of the cellular
system; so that, when you examine the trunk of a tree,
you perceive zones of woody fibre and zones of the cel-
lular system.
EMILY.—Can the age of endogenous plants be ascer-
tained in the same manner 7
Mrs. B.-No ; the annual layers of wood are not suffi-
ciently distinct from each other.
CARolisE.—But the rings annually formed by the ves-
tiges of leaves is a still better record of their age, for it
is not necessary to cut down the tree in order to ascer-
tain it.
MRs. B.-For a certain period they may answer this
purpose; but these vestiges are obliterated by time, and
in an aged tree are no longer distinguishable towards the
base of the stem.
BARK.—The vegetation of the bark is precisely the
inverse of that of the wood; that is to say, it is endoge-
nous, its layers growing internally like those of the palm-
tree : the new soft coat of bark therefore lies immediately
in contact with the new soft layer of wood.
ExIILY.—But if a fresh layer of bark grows every
year, why is the bark so much thinner than the wood
should have supposed that they would have been of equal
dimensions?
WIRs. B.—The outer coats of bark, when they become
too hard to be farther distended by the pressure of the
internal layers, crack, and, becoming thus exposed to
the injury of the weather, fall off in pieces: it is this
which produces the ruggedness of the bark of some
trees. In others, the rind, though smooth, peels off, at.
ter cracking, like that of the cherry, the birch, and par-
ticularly the plane-tree. Those trees whose external
ON STEMS. 45
Coat of bark is least liable to peel off, such as the oak
and the elm, become more scarred and rugged, in pro-
portion as the tree grows older, and is longer exposed to
the action of air, water, insects, and parasitical plants:
sooner or later these various causes effect the destruction
of the outer bark; and the other layers, as they become
external and exposed to the same sources of injury, expe-
rience, in due course of time, the same fate; while the
layers of wood, being protected and sheltered by the
bark, vegetate in security.
CARoll NE.-Yet it is not uncommon to see the trunkº
of very old trees in a state of total decay, while the bark
remains uninjured.
MRs. B.-That is the case when the wood is, by any
accidental circumstances, exposed to the inclemencies of
the weather, which it is not calculated to resist. This
happens, sometimes, by the lopping or breaking off of
large branches, considerable pieces of bark falling off,
or any circumstance by which the rain can gain admit-
tance to the wood.
There are some trees whose bark is of so elastic and
yielding a nature, that it does not harden for a considera-
ble number of years. The bark of the cork-tree, for in-
stance (which is the part commonly called cork,) does not
begin to harden till after the age of seven years : care is
taken to strip it off for the use of the arts before that pe.
riod. The bark of the plane tree is, on the contrary, of
so hard and inflexible a texture, that it cannot expand,
but splits and falls off every season. These two species
of trees, the cork and the plane tree, form the two extre-
mities in the scale of varieties of texture in the nature
of bark. The cuticle or external coating of bark is not
confined to the stems and branches, but spreads itself
over the leaves, and every part of the surface of the
plant which is of a green colour.
ExIILY.—But the bark of trees is not of a green co-
lour, Mrs. B.
MRs. B.—Recollect that the cuticle is an envelope,
which lasts seldom more than a twelvemonth. In those
parts of a plant which are of longer duration, such as
16 ON STEMS.
the stem and branches of trees, the cuticle decays and
peels off; and its place is supplied by the epidermis, a
coating formed by the desiccation of the external part of
the cellular tissue which has been left exposed to the air.
The epidermis, therefore is not green.
Aquatic plants form the only exception, these having,
properly speaking, no epidermis.
If you pass a silver wire or blade completely through
the bark of a tree, the new internal layers, as they are
annually formed, will gradually push it outward, till at
length the internal coat becoming external, the wire will
fall off.
CARolf NE.-That is, no doubt, the cause why inscrip-
tions on the bark of trees are, in the course of time,
effaced : the new bark does not grow over them it is true,
but growing under them, the inscription becomes distend.
ed, and when the bark gives way, it will most readily
split and fall off where the inscription has already
wounded it.
EMILY.—If, however, the inscription be made so deep
as to penetrate the layers of wood, the new layers of
bark, instead of injuring, will preserve it.
CARo1.INE.-But of what use will be its preservation,
while it is so buried as to be totally lost to the sight
MRs. B.-Buried treasures are sometimes brought to
light. Adamson relates, that, in visiting Cape Verd in
the year 1748, he was struck by the venerable appear-
ance of a tree, 50 feet in circuinference. He recollected
having read in some old voyages an account of an in-
scription made in a tree thus situated. No traces of such
an inscription remained, but the position of the tree
having been accurately described, Adamson was induced
to search for it by cutting into the tree, when, to his great
satisfaction, he discovered the inscription entire, under
no less a covering than three hundred layers of wood.
CARolliXE.—Three hundred years, then, had elapsed
since the inscription had been made How much he
must have been gratified by the discovery —But did not
his venerable tree suffer from such deep wounds !
ON STEMS. 47
EMILY.—Probably not: for, according to the size of
the tree, though he cut so deep, he was still far distant
from the centre.
MRs. B.-The centre is not the most dangerous part;
on the contrary, the vital part of the stem is situated be.
tween the young layers of wood and those of the bark;
or perhaps the vitality may be exclusively confined to the
inner coat of the bark: for if the young layer of wood
be destroyed by frost, the tree suffers but little; while, if
the inner coat of bark be frozen, the plant infallibly
perishes. In the trunk of a tree which has been cut
down, it is very easy to trace the effect of frost on any
layer that has been injured by it, the wood appearing
withered and wrinkled. Mr. De Candolle observed a
frostbitten part of this description in a tree cut down in
the forest of Fontainbleau in the year 1800; and, by
counting the superincumbent layers of wood, he ascer-
tained that it must have happened in the year 1709, one
which was remarkable for the severity of the frost.
EMILY.—But since the layers of wood grow with so
much regularity, whence come those knots and waving
lines, which constitute the beauty of polished wood 1
MRs. B.-If the sap, in rising through the young wood,
meets with any casual obstruction to its passage, it natu-
rally accumulates in that spot, and forms what is called a
knot. This consists of distended vessels, containing a
magazine of food, which gives birth to a germ or shoot;
but it frequently happens that, before this germ has at-
tained strength to force its way through the bark into the
open air, a new layer of wood rises over and encloses it.
Sometimes it is only temporarily buried; and the follow-
ing season it acquires sufficient vigour to break through
its prison. Thus, if the shoot go on annually forcing its
way thröugh the wooden wall which rises up to oppose
its progress till it reaches the surface of the stem, it be.
comes the origin of an external shoot or branch. If, on
the contrary, it is exhausted by this series of struggles, it
perishes; and leaves, in memorial of its efforts, the knots,
waves, and streaks, which embellish its tomb. This shoot,
which had increased in size while traversing the several
48 ON STEMS.
layers of wood, as soon as it grows externally, diminish-
es as it protrudes in the air, being thickest at the stem,
and tapering towards its extremity; so that a shoot, if
traced from its origin, exhibits the form of a double cone,
the base of which is at the surface of the stem.
ExIILY.—But whence did this shoot derive its origin?
The accumulation of sap can merely favour its growth,
but cannot have given it existence.
MRs. B.-This is a question not very easily answered;
but the opinion most prevalent among botanists is, that
germs or latent shoots exist throughout the stems and
branches of plants, and that those only are brought into
a state of active vegetation which are fully supplied with
food.
CARolisE.—Do the stems and branches of exogenous
plants grow like their roots, merely at their extremities :
MRs. B.-No; they increase throughout their whole
length. If you make marks at certain distances on a
root, you will find that these distances are not altered by
growth; but if you make similar marks on a stem or a
branch, the distances will increase, showing that it grows
in its whole extent.
EMILY.—It must be so, since a new layer of wood
grows annually at the base.
And pray, through what part of the stem does the sap
rise 1
Mrs. B.-That is a question which has been long and
much disputed. Some naturalists have maintained the
opinion that it ascended through the pith : others, that it
rose through the bark; and they have reciprocally pro-
ved each other to be mistaken in their conjectures. A
third road was, therefore, sought for; and, by colouring
the water with which a plant was watered, it has been
traced within the stem, and found to ascend almost wholly
in the alburnum or young wood, and particularly in the
latest layers.
CARollSE.—That is very natural. The perfect wood
has in a manner finished its active career: it can itself
acquire but little nourishment; and its indurated texture
ON LEAVES. 49,
would be ill adapted to the conveyance of the sap, while
the young layers being in the full vigour of growth, and
their cellular system flexible and elastic, are much better
ealculated to transmit it; besides, it is in these, you say,
that the young shoots take their origin.
Mrs. B.—The sap does not impart nourishment to the
plant during its ascent: it is therefore more probable that
its rising through the new wood is owing to that being
softest and most permeable. By means of the coloured
medium I have mentioned, it was observed that the sap
naturally ascended in straight lines, but that, if it encoun-
tered any obstacle, it could move obliquely, or even
spread itself laterally.
A great variety of experiments have been made in or-
der to ascertain the degree of velocity with which the
Sap rises; but as the rapidity of its ascension depends in
a great measure upon the means which the plant has of
parting with it by exhalation, we cannot well follow its
progress without having previously made acquaintance
with the excretory organs of plants—the leaves, whose
office it is to exhale that portion of the sap which is su-
perfluous.
CARoline.—The whole of the sap then is not required
for the nourishment of the plant 1
Mrs. B.—That 11ourishment is a limore complicated
operation than you are aware of: all the water which
enters into the plant is not retained by it; part of it
passes through the leaves into the atmosphere, and the
atmosphere, in its turn, contributes to the nourishment of
the plant. But we must not anticipate; and, at our next
interview, we will examine the structure and agency of
the leaves of plants.
CONVERSATION IV.
ON LEAV ES.
MRs. B.-There is nothing more beautiful in the ve.
getable creation than the gradual formation and deve-
5
50 ON LEAVES.
lopement of a leaf. It consists of the flattened expan-
sion of the fibres of the stem from which it shoots, con-
nected together by a layer of cellular tissue called the
pabulum, and the whole is covered by a delicate coating
of cuticle, which is almost always of a green colour. A
plant may, indeed, be considered as a continued series
of these fibres, sometimes closely bound up in the form
of stems, at others spread out into that of leaves.
CAROLINE.-Yet surely, Mrs. B., there are many
parts of a plant which can neither be referred to leaves
nor stems? The blossom, the fruit, and such occasional
appendages as thorns, and tendrils, cannot come under
either of these denominations !
MRs. B.-I beg your pardon : they all originate in
leaves. Even the seed, when first ushered into life,
comes cradled in a folded leaf; but as in assuming the
form of a seed-vessel it looses that of a leaf, we must
not allow it to encroach upon the present subject of our
conversation, that of leaves properly speaking, which
retain their originul form throughout the whole of their
transitory existence.
CARoll NE.-Well, it must be confessed that this bor-
ders on the marvellous; but I shall take it on your autho-
rity till the time comes for you to explain it more fully.
MRs. B.—It rests upon much better authority than
mine : it is sanctioned not only by the opinion of Mr.
De Candolle, but also by the celebrated Mr. Brown, who
was the first to develope this theory in England. In
Germany, so long as thirty years ago, the venerable
poet Goethe wrote a small treatise on the metamorpho-
ses of plants; and if this little work has not met with the
attention it deserves, it is probable, that, being written by
a poet, it has been considered rather as the effusion of
an ardent imagination, than as the deductions of a philo-
sopher. But, whatever be the changes which leaves may
undergo, it is our present business to treat of them in
their state of leaves.
If, when a leaf shoots, the fibres which attach it to the
stem or branch spread out immediately, the leaf is term-
ed sessile or continuous; for it cannot be separated from
ON LEAVES. 51
the stem without the fibres being torn asunder; the leaves
of corn, grasses, and all gramineous plants, are of this
description.
Extily.—But it is much more common for leaves to be
attached to the branch by a foot-stalk.
MRs. B.-With exogenous plants it is; and the trees and
shrubs of our temperate climate are almost all of that class.
Such leaves are said to be articulated; the fibres when
they first separate from the stem remain bound together,
forming the petiole or foot-stalk; thence they expand in
numerous ramifications, constituting the ribs of the leaf.
Let us now examine this leaf of a horse-chesnut: I cut
it transversely at its base, and you may perceive with the
naked eye ſhe larger vessels which convey the sap into
the leaf. At the other extremity of the foot-stalk they
are also visible. They are five in number, correspond-
ing with the five leaflets of which the horse-chesnut leaf
is composed.
The fibres of leaves spread out in various directions:
the principle one, dividing the leaf from the base to the
summit, is called the dorsal, or mid-rib ; others branch
out from this laterally ; and a third class consists of still
smaller ramifications issuing from these last; they all
terminate at the surface of the leaf by a pore called
stoma, a Greek word, signifying mouth-
CARoll NE.—These are, no doubt, the exhaling pores
which send off the superfluous moisture.
MRs. B.-Yes; but we must patiently labour through
a forest of foliage, before we can return to the physiolo-
gical operations of the plant.
Leaves are usually divided by botanists into five classes.
according to the direction of their ribs :—
First, the pennated are those in which the smaller ribs
expand from the principal rib like the feathers of a quill :
the leaves of the pear and the lime-tree are of this de-
scription. The second class is palmated. In these, the
ribs diverge from the petiole like the fingers from the
palm of the hand, as you see in this vine-leaf. They
are not, however, always five in number, varying not only
52 ON LEAVES,
in different plants, but sometimes in different leaves of
the same individual.
The third class is called target-shaped, or peltate, being
shaped like a buckler; such is the nasturtium.
The fourth class is pedatum, having the form of the
foot: the hellebore is of this class.
The fifth class has simple ribs, proceeding from the
base to the extremity of the leaf; corn, grasses, and all
the gramineous tribe are comprised within it. These
leaves are always sessile.
The contour, or external form of the leaf, is of much
less importance than the direction of its ribs. The in-
dentures, or teeth of leaves, are formed by the termina-
tion of its ribs.
ln the gramineous tribe, the leaves are smooth at the
margin, and have no indentures; the ribs run on each
side along the margin like a small seam, and terminate
at its pointed extremity, whence all the exhalations take
lace.
When the indentures of some leaves reach so far as
half-way down, they are said to be pinnatified; and when
the leaves, though soparate, grow from one foot-stalk, so
that one of them cannot fall off, or be separated from the
other without being torn asunder, the leaf is said to be
dissected.
CAROLINE.-There are a great variety of leaves of
this description: the rose, the acacia—
MRs. B.-No ; these are compound leaves, and differ
from the dissected by being articulated, each leaflet
having a separate foot-stalk, which, when the leaf dies,
detaches the leaflet from the general foot-stalk, and they
fall separately.
At the base of the foot-stalk of compound leaves there
generally grows a small organ, called stipula : it consists
of two accessary leaves, as you see here in the rose-leaf,
the willow, and indeed in most exogenous plants. Some-
times the stipula is attached to the foot-stalk, at others to
the stem : it withers easily, and often falls off before the
other leaves; for which reason it is not always to be met
with on branches of a certain age? In this branch of
ON LEAVES. 53
rose-tree, you see that there are stipulae to all the younger
shoots, while the older ones have already lost them. In
the pea the stipula is larger than the common leaves.
[See Plate I.]
When the ribs of leaves are expanded upon the same
plane, the leaf is thin ; in succulent plants, which retain
moisture and evaporate but little, the cellular tissue,
which connects the vessels of the upper and lower Sur-
face of the leaf, is thick and fleshy.
The two surfaces of a leaf generally differ in appear-
ance : in the upper surface the ribs are the least promi-
nent, and the leaf is consequently the smoothest, and of
the deepest green. The under surface is more hairy, and
abounds with stomas or pores; the upper has fewer, or is
sometimes wholly deprived of them, excepting in aquatic
plants, whose leaves float on the water; their upper sur-
face being alone exposed to the air, are alone supplied
with stomas.
But whether the two surfaces be similar or not, it is
very certain that their functions are different; for if you
reverse the leaf of a plant, and prevent it from resuming
-its natural position, it will wither and die.
EMILY.—But corn and grasses grow vertically, Mrs.
B., and can scarcely be said to have an upper and an
under surface ; though, it is true, they are greener and
smoother on one side than on the other.
MRs. B.-All the gramineous family have a more equal
distribution of pores on either surface; for growing near-
ly erect, and being therefore equally exposed to the air,
each surface can probably perform the same functions,
and these plants can bear the reversion of their leaves
better than any other..
Floating aquatic plants, on the contrary, having no
pores on their lower surface, infallibly die if they are
leversed without power of resuming their natural position.
CARoll NE.-It would be superfluous for aquatic plants
to be furnished with pores on their under surface, since
they could not evaporate into water.
MRs. B.-Nor can they elaborate the sap without ex-
posing it, by means of the º to the atmosphere : but
54 ON LEAVES,
we must complete the anatomical examination of the
structure of the leaf, before we enter upon its physiolo-
gical functions.
The first appearance of leaves which the young plant
puts forth on the germination of the seed is formed by
the lobes of the seed itself, which we have already no.
ticed under the name of cotyledons.
EMILY.—I have often observed them in lupines, when
they first shoot above ground, and wondered that the tiny
plant should be able to supply food to such thick substan-
tial leaves.
Mrs. B.-It is, on the contrary, these leaves which
yield their substance to the tiny plant; and as soon as
they have completed this function, and the whole of their
pulpy nutriment is consumed, they wither and fall off.
But all cotyledons are not of a succulent nature: some
are thin, like other leaves, and are more commonly called
seminal or seed leaves.
EMILY.—IIow, then, can they feed the young plant?
MRs. B.-By immediately claborating the sap, which
the nascent root draws up from the soil. Seminal leaves
are furnished with stomas for this purpose, while fleshy
cotyledons have none ; in the latter, the conversion of the
cotyledons into leaves is but very imperfect; they fre-
quently remain under ground, and do not assume either
the form or colour of a leaf.
EMILY.—The cotyledons of pens and beans are of this
description; in those of lupines the conversion is more
complete, though they remain succulent.
CARoLINE.-Since the fleshy cotyledons have no sto-
mas, I know not what they have to do in the open air :
merely acting the part of a magazine of food, they are
more at hand to supply the young plant with it under
ground than above it.
EMILY.—But is it not wonderful that a young plant
should be able to absorb sap, and elaborate it from the
first moment of its existence 1
MRs. B.-Not more so than that a young chicken
should pick up grains of corn as soon as it has throwſ
ON LEAVES. 55
ºf its egg-shell. Nature has probably given more firm.
ness and stability to the roots of plants, which are obliged
immediately to provide their own food, in the same way as
she has to the beaks of young birds. The embryo plant
has often another resource, but which does not belong to
our present subject.
The first regular leaves which expand are called pri-
mordial, and are not unfrequently of a different character
from the common leaves of the plant.
When the leaves shoot very near the ground, so as to
appear to grow from the roots, they are called radical
leaves; they sprout, however, from the base of the stem,
for roots never give birth to leaves.
Bractea, or floral leaves are, on the contrary, leaves
peculiar to some plants, which grow very near the flower,
and are often mistaken for blossom, not being always of a
green colour. The Hydrangea, for instance, has a great
abundance of pink or lilac bractea, which I doubt not but
that you have supposed to be the flower of that plant.
CARolrxe.—Are then those beautiful blossoms of the
hydrangea not its flowers?
MRs. B.-To a superficial observer they bear, it is
true, a much greater resemblance to flowers than to leaves;
but, if examined attentively, you will find they possess
ſew of the regular organs of the flower, and could produce
neither fruit nor seed.
ExILY.—Is there any other example of coloured leaves
which are bracted instead of blossoms ?
Mrs. B.-A great number. The lime-tree shoots out
a profusion of bractea of a pale yellow colour; and 1
doubt not but that you have confounded them with the
hlossom which lies concealed beneath them. The co-
loured leaves of the red-topped Clary, which exhibit va-
rious tints of red, purple, and green, are also of this de-
scription. There are many bractete which do not differ
either in colour or form from the other leaves of the plant,
and are distinguished only by their situation with regard
to the flower. Such is the tuft of leaves on the summit
of the flower called, the crown-imperial, and that which
grows from the top of the pine-apple : the scaly covering
50 ON LEAVES.
of this fruit consists also of the remnants of degencrated
bractea.
CARoline.—And pray, Mrs. B., is not the scaly cone
of the fir-tree of the same nature ? I have often observed
it when the seeds have fallen out, and it wears the appear-
ance of an aggregation of short, thick, stiff leaves forming
a cone of cells somewhat resembling a bee-hive.
MRs. B.-You are quite right; except in calling the
fruit which is lodged in these cells seeds : their botanical
name is achenium.
Both the fir-cone and the pine-apple are aggregated
fruits, separated by bractea ; but in the succulent pine-
apple, almost all vestiges of the intervening bractea arc
obliterated.
Extrix.--When the crown of the pine-apple is pulled
off, the summit of the fruit, I think, exhibits some manks
of cells formed by bracteac.
MRs. B.—That is true ; and they are, you may have
observed, empty : the pressure of the base of the crown
having prevented the fruit from growing, the bractea arc
not wholly obliterated.
Leaves are arranged on the stem in a great variety of
ways: sometimes in opposite pairs, and the successive
pairs crossing each other at right angles; at others, seve-
ral leaves shoot from the same spot, and spread out in a
circle. They sometimes alternate on the stem, and ap-
pear irregularly scattered ; but Nature allows nothing to
be scattered by chance ; upon a care ful investigation, or-
der and method will be discerned in the minutest of her
works; and, in the arrangement of leaves on the stem.
she has been studious to prevent their covering each
other too closely, both light and air being required to ena-
ble them to perform their functions.
ExIILY.—Is it not surprising that Nature should have
bestowed so much pains upon so insignificant a part of
the creation as a leaf; which, however beautiful and cu-
riously constructed, lasts but a season, and is then scat-
tered by the first blast of wind, and trodden under foot ?
MRs. B.-Not until it has performed the part which
Nature has assigned to it; and when you are acquainte"
ON LEAVES. 57
with the importance of its functions in the vegetable eco-
nomy, you will probably be induced to treat it with more
respect.
CARoline.—Leaves, when they first shoot, are gene-
rally enclosed in small scaly buds, evidently designed to
protect them from inclemency of weather. Now these
scales differ totally in forin and appearance from the
leaves they shelter; and I think, Mrs. B., that you would
be at a loss to derive them from the same origin
MRs. B.-Nothing more simple. All leaves begin to
shoot without any external covering ; but when, in early
spring, they quit the protecting branch in which they were
embosomed, to enter into the cold region of the atmo-
sphere, they are chilled and checked in their growth,
and, instead of expanding in the natural form, they con-
tract, harden, curve inwards, and are finally transformed
into a species of scales, which serve to protect the inter-
nal leaves: under so friendly a covering, these vegetate
freely. In the mean time the season advances, the atmo-
sphere acquires heat, and the young leaves, having been
protected from its former inclemency, are cherished and
developed by its genial influence.
EMILY.—What a beautiful provision for the security of
a leaf
Mrs. B.-If you follow up the developement of the
bud of the ash or the maple, you will observe that the ex-
termal scales are short, hard, reddish, and rather hairy.
In proportion as they are more internal, they become
membranaceous, pale-coloured, and elongated; small ru-
diments of leaves then appear at their extremities; and
these, shortly after assume the form of leaflets, so very
different in shape and structure from the external scales,
that it is difficult to conceive they have had the same
origin.
EMILY.—The more feeble and delicate the leaves of a
plant are, the greater, I suppose, will be the number of
those which degenerate into scales; therefore, the thicker
and warmer will be the covering for the leaves which are
ſiltimately to be developed.
('ARoll NE.-And these, being of the same delicate
58 ON LEAVES.
texture, require such an additional clothing. What an
admirable effect produced from so simple a cause !
Mrs. B.-These scaly leaf-buds are not universal,
some leaves being of so hardy a nature as not to require
a covering, especially when growing in a warm climate :
they are then said to grow naked; but being closely folded
or rolled up in a small compass when first they shoot,
they wear the appearance of a smooth bud without scales.
The horse-chesnut, in its native climate of India, un-
folds its young leaves to the general atmosphere, without
risk of their suffering from exposure : while, in this colder
country, many successive leaflets are arrested in their
growth, and condemned to degenerate into scales. If you
examine the buds on this branch, you will see what num-
bers have changed their form, and are reduced to play a
subordinate part in the system of vegetation.
The scales of some buds are formed from the rudiments
of stipula: ; others derive their origin from petioles or
footstalks; which, instead of growing long and slender,
expand and assume the form of scales, and envelope the
embryo shoot. The buds of the walnut and the pear are
formed from stipulac.
EMILY.—I have often examined these buds with great
interest, and admired the ingenious manner in which the
leaves were so closely packed, in order to be contained
within them. Do the same buds produce both leaves and
ſlowers ?
MRs. B.-Buds vary in this respect not only in different
plants, but sometimes even in the same individual ; some
sprouting into flowers and fruits; others into leaves only,
and branches; and there are buds of a third description,
which develope both fruit and leaves. The first kind is
full and round; the second, smaller and more pointed ;
and the third, both in size and shape, forms a medium be-
tween the other two.
CARolise.—How essential it must be for a gardener
to be able to distinguish these buds ! For if, in pruning a
tree, he were to lop the branches which contained most
of the fruit-buds, and retain those which had more leaf-
buds, he would have a very poor crop of fruit. Are these
three species of buds common to all trees?
ON LEAVES, 59
MRs. B–No; the buds of the horse-chesnut, which are
So large, scaly, and glutinous, are all of the mixed kind;
those of the apple and pear are of the two distinct species.
Endogenous plants, or monocotyledons, scarcely ever
produce more than one single bud annually; the cabbage
of the palm-tree is its bud, and the leaves and flowers are
folded within it. The cocoa-nut and date trees develope
their flowers and foliage in the same manner.
Bulbous plants (the endogenous plants of our temperate
climate) are of the same description. I have already ob.
served, that their stem is contained within the bulb ; but
you have yet to learn that this bulb is in fact the bud or
cabbage, containing not only the stem, but also the leaves
and flowers. The scales formed for the rudiments of
undeveloped leaves are particularly distinct in bulbous
roots, especially in the onion.
ExIILY.—Thus then a lily, a tulip, or a hyacinth, are
all contained within their bulbs, which we have been ac-
customed to consider merely as their root. But these
flowers have each a stem, Mrs. B., independently of that
which you say remains undeveloped within the bulb.
MRs. B.-The shoot which you consider as a stem, is
the peduncle or footstalk of the flower, not the stem of
the plant; the leaves which grow from the stem shoot
from beneath the foot-stalk. The bud or cabbage of the
alm-tree, when developed, shoots up a foot-stalk on
which the flower expands, while the leaves spread out at
its base. The difference between these plants of the
tropical and of the temperate zones is, that the stem of the
palm-tree being developed, the cabbage is situated at its
summit; while, in our more temperate climate, the vege-
tation of the bulbous plants is not sufficiently vigorous
fully to develope their organs, and the stem remains in a
latent state within the bulb.
CARolls E.-How can those plants bud whose stem
and branches die annually, such as dahlias, paeonies, and
( hina asters, &c. 1
MRs. B.-The new stem and branches shoot from a
bud formed at that vital spot called the neck of the plant;
in perennials the stem dies down to this spot, but if that
Ü0 ON LEAVES,
perishes, the whole plant dies. It is situated either on a
level with, or rather below, the ground; and the bud be.
ing but little exposed to the weather, is not provided with
the same warm covering as most of those which sproutin
the air.
CARolisE.—That is to say, being protected by their
situation, the first rudiments of their leaves do not dege-
nerate into scales.
And pray, do all these various kind of buds originate
in some little accumulation of sap in the stem, in the man-
her you have described to us?
MRs. B.-This accumulation of sap is the origin of
a bud, so far only as it enables a germ or embryo shoot
to grow, by affording it an ample supply of food.
They commonly shoot at the articulation of a leaf,
because the branching off of the vessels offers some
little impediment to the flowing of the sap ; a small por-
tion of it is arrested in its course, and forms a deposition
of food, which a neighbouring germ quickly applies to its
own use, and is thus ushered into life.
EMILY.—Such germs must exist then in a latent state
in every part of the stem, and wait only for means of sus-
tenance to make their appearance externally.
MRs. B.—In all probability; for wherever there is an
accumulation of sap, a germ is sure to be developed.
EMILY.—When I plant a slip of geranium, I take care
that is should have at least one leaf; because I know by
experience, though I was quite ignorant of the cause, that
the shoot would spring from the articulation of the leaf.
MRs. B.-In geraniums there is also another species
of articulation, consisting of knots in the stem, which
answers the same purpose, by interrupting in some mea-
sure the circulation of the juices, and affording a little
supply of stagnant sap. Pinks and carnations, reeds and
rushes, the stems of corn and grass, are all intersected in
a similar manner.
CARolrwn.—Then when carnations and pinks are
propagated by layers, the shoots take place at those in-
ter-f ctions ºf the stern.
t)N LEAVES. 61
Extily.—Excepting the geranium, the leaves of all
these plants are, I believe, sessile; the intersections in
the stems must therefore supply the place of articulations
in furnishing the buds with food.
Mrs. B.-Precisely so. They belong to the class of
endogenous plants, whose leaves are more rarely articu-
lated than those which are exogenous. These intersec-
tions, however, not unfrequently occur in the latter, as
with the geranium, the vine, and several other dicotyle-
dons.
You may recollect my observing, that a number of
years frequently elapsed before the buds formed on the
stem or branches of a tree attained sufficient strength to
force their way through the successive layers of new
bark which annually enclosed them ; while others vigor-
ously pushed through this barrier the first year. Buds
usually begin to be formed in the month of August, and
remain in a latent state during the winter, when they are
commonly called eyes: the following spring they shoot;
but they cannot properly be called buds till the scales are
formed by the degeneration of the external leaves of the
shoot.
It is heat which determines the period of budding of a
plant. A branch turned towards the south, or introduced
into a greenhouse, will shoot long before the rest of the
tree; the budding begins to appear first ‘near the extre-
mity of the branches, where the wood is most soft and
tender.
ExIILY.—I should have imagined that the base of the
branch, which the sap first reaches, would have budded
carliest.
MRs. B.-In the larch, and many other trees whose
branches are equally hard throughout, this is the case;
but the superior facility of piercing through the tender
part of a branch more than compensates for the earlier
supply of food.
The scales of buds are often coated with a sort of glu-
tinous varnish, which resists moisture; some are lined
with a species of down or fur, to preserve the internal
shoot from cold.
6
62 ON LEAVES,
CARolisE.—But can down or fur result from the dege.
neration of leaves | Such a beneficent provision for the
protection of the shoot would seem to indicate, that the
bud of a distinct organ is specifically designed for that
purpose.
MRs. B.-Such is no doubt equally its destination,
whether it originate in the abortion of another organ, or
whether expressly created for that purpose; nor is it
difficult to refer the formation of down or varnish to the
same origin. The scales of buds probably absorb from
the sap only a portion of what was destined to nourish
them had they been developed into leaves, and the remain-
der may be converted into a species of glutinous resin
or varnish. The rudiments of leaves, when examined in
the bud before it is developed, wear the appearance of
small filaments of cotton, which, when spread out, exhibit
the minute skeleton of a leaf.
It would be difficult to suggest a mode of folding or
rolling which nature has not adopted in enclosing these
embryo leaves in the bud. They are sometimes, as those
of the vine, folded like a fan; others are doubled from
the top to the bottom; others folded down the middle ;
some are laid one within another; others closely packed
side by side ; and there are an equal number of modes of
rolling them up in the buds.
In some plants, the petioles or foot-stalks retain the
nourishment they should transmit to the leaves, so as to
prevent the latter from being fully developed ; they re-
main therefore in an embryo state; the petiole, in the
mean time, gorged with nutriment, becomes thick, corpu-
lent, and clumsy, flattening as it expands, and wears
rather the appearance of a leaf than of a stalk. The
acacia of New Holland has this singular conformation.
CARoline.—I have seen tropical plants in hothouses of
this description: the prickly fig is, I believe, one of them.
But how do these leafless plants disburden themselves of
the superfluous moisture which leaves exhale 1
MRs. B.-The dilated petioles, which usurp the place
of leaves, perform also, though but imperfectly, their
functions, and have pores adapted for that purpose: they
ON LEAVES. 63
are not however leaves, any more than the tail of a kan-
garoo is a leg, or the trunk of the elephant an arm, though
they respectively perform the office of these members.
When common organs assume in certain species an un-
common form, they may be useful for purposes different
from those for which Nature originally designed them :
but they should not on that account obtain the name of
the organ they but imperfectly imitate.
Leaves are usually deciduous, that is to say, last but
one season: there are but few exceptions of plants whose
leaves last two, three, and sometimes as long as four
years. Evergreens change their leaves annually, and
the plant remains green only because the young leaves
appear before the old ones decay.
EMILY.—Is it not singular that the leaves of evergreens
should wither and fall in the spring, when the weather
becomes warm, the sap most abundant, and vegetation in
full vigour !
MRs. B.-A leaf withers when the vessels which should
bring it nourishment are no longer capable of performing
that function. In autumn, the vessels of the petiole be-
come obstructed by a deposition of hard matter, which
disables them from transmitting sap, and being no longer
moistened by the passage of this fluid, they dry up and
wither ; while the pabulum of the leaf, consisting of an
expansion of the cellular system, which is of a soft, moist
mature, preserves the leaf some little time after the petiole
has ceased to perform its functions.
CARolin E.-Like an animal deprived of sustenance, it
ſeeds on its own fat, before it perishes.
MRs. B-The circulation of sap in evergreens being
more uniform throughout the year, the deposition of hard
matter does not obstruct the passage of the sap till to-
wards the spring, when the vigorous sap is directed to-
wards the buds, and the old leaves drop off as the young
ones expand.
The petioles of some leaves, such as the aspen and the
poplar, are flattened, and adhere less firmly to the stem ;
hence they tremble at every breath of wind, and fall off
more readily than those of a cylindrical form.
64 ON SAP.
With regard to the most important functions of the
leaves, the chemical changes they operate upon the sap,
we must reserve them for our next interview, which I
propose to dedicate to the examination of the sap, and the
interesting part it performs in the vegetable system.
CONVERSATION V.
ON S.A.P.
MRs. B.-Now that you have made acquaintance with
the root, the stem, and the leaves, we may proceed to trace
the sap in its ascent through these several organs, observe
the various transformations it undergoes in the leaves.
and, following it in its descent, examine the manner in
which it feeds and restores the several parts of the plant.
CARolix E.-This seems to me to comprise the whole
history of vegetation.
MRs. B.-In a general point of view it does, but we
shall yet have many details to enter into ; besides what I
have hitherto said relates only to the nourishment of
plants : their re-production is of no less importance, and
we have not yet ever alluded to the flower, the most dis-
tinguished and beautiful of their organs, and that in
which the seed originates.
Extily.—But this sap, Mrs. B., which I imagined to
be diffused through the plant as it rose, seems to be dis-
posed of in a very different manner: part, you say, is ex-
haled by the leaves, and part descends through the bark;
what then remains to nourish the plant?
MRs., B.-All that is necessary for that purpose is
selected and retained. If you consider that the sap
which rises in the roots consists simply of water, holding
in solution a variety of crude ingredients, such as lime,
silex, magnesia, soda, and potash, you will acknowledge
that something more is required than the mere diffusion
of this hetrogeneous fluid through the plant in order to
nourish it. The sap traverses the stem, rising, as I have
already said, through the alburnum, and some small por.
ON SAP, 65
tion of it through the perfect wood. A great variety of
experiments have been made, with a view of ascertaining
the degree of rapidity with which the sap ascends. M.
Bonnet raised some plants in a dark cellar, in order to
blanch their stems, that he might be able to trace the
ascent of the coloured water with which he nourished
them. He found that this tinted sap rose only four inches
in two hours; but the plants, owing to the disadvanta-
geous circumstances under which they were cultivated,
were weak and sickly; in subsequent experiments on
more healthy plants, the sap was seen to ascend three
inches in the course of an hour. Some time afterwards
Mr. Hales immersed a fresh cut branch of a vigorous
pear-tree in a tube full of water, and found that the sap
rose in it eight inches in six minutes.
EMILY.—And how do you account for so remarkable
a difference in the result of these experiments?
Mrs. B.-Chiefly from the improved mode of per-
forming them. The velocity of the sap varies, however,
very considerably, owing to a variety of causes: the na-
ture of the plant, the degree of temperature, and, above
all, the quantity of solar light; which last is absolutely
required to enable the leaves to evaporate the superfluous
Water.
During the spring there is more than usual absorption
of sap, for the purpose of nourishing the young buds
which are to be developed; and it is very worthy of re-
mark, that the sap which feeds these buds passes through
different channels from that which serves to nourish the
plant generally. Instead of rising through the young
wood, it ascends nearly in the centre of the stem, in the
parts contiguous to the medullary channel, and is thence
transmitted, by what means is not yet ascertained, through
the several layers of wood to the buds.
Ewily.—But the sap that nourishes the buds which
first shoot in the spring, cannot have been passed through
the leaves, and undergone that change which you say
is necessary to convert it into appropriate food. Can it
feed the buds in the crude state in which it rises in the
8tem "
G*
66 ON SAP.
Mrs. B.-There is great reason to suppose that it is
in some measure elaborated during its passage from the
roots to the buds; probably by the organs which it tra-
verses in passing laterally from the centre to the circum-
ference of the stem or branch ; but it is a point very
difficult to ascertain, owing to the extreme minuteness of
these organs : it is, however, a very reasonable inference.
since the sap, when it reaches the buds, is in a state ready
to be assimilated to their substance.
Part of the sap, which rises in the month of August, in
all probability follows the same course, being destined to
nourish the new buds which shoot at that season ; but it
is less abundant than that of March, having fewer buds
to bring forth.
EMILY.—How much this sap, destined for the nourish-
ment of the young buds, resembles the milk of animals.
a provision which Nature has made for a similar purpose,
and which is secreted from the common stock of nourish-
ment only when there are young to feed on it.
And pray, what is the cause that produces the rising of
the sap in spring 7
Mrs. B.-Heat is the circumstance most favourable to
the absorption of this nursling sap, as it is heat which
first expands the buds, and makes room for it. An expe-
riment has been made by placing two pieces of vine in
two similar vases of water, and then introducing the stem
and branches of one of them, thrºugh a hole in the wall.
into a hothouse : the buds of this plant were rapidly de-
veloped, and the water in the vase as rapidly absorbed :
while the buds of the other plant made only the usual
progress, and the water in the vase diminished in the
same slow proportion.
If plants are pruned in the spring, the sap will rush
out often with violence : in vineyards, this flowing of the
sap, when plants are cut, is called the tears of the vine.
Mr. Hales made an experiment by cutting off the upper
end of the branch of a vine, and enclosing the wounded
extremity of the lower part (which remained on the stem)
in a tube; the sap flowed from it with such violence, and
in such albundance, as to rise to the height of forty-three
ON SAP. 67
feet in the tube, thus sustaining the weight of one atmo.
sphere and a half.
Caroline-What a prodigious force! Of course, iſ
you make an incision into the stem of a tree in the spring,
the sap will flow out.
MRs. B.-No, not at least with violence, for the spring
sap rises with force, only in shoots of one year's growth,
and will consequently flow with velocity from none but
these. In making the incision, you must penetrate to the
centre in order to reach the full channel of the spring
sap, and the instant your instrument reaches the pith, you
will hear the sap gush, and see it follow the instrument
as you draw it out.
We must not, however, bestow the whole of our atten-
tion on this nursling stup, but return to that which rises
through the alburnum to feed the Inature plant. This
sap reaches the leaves without having undergone any
change; but as soon as it arrives there, a considerable
portion of its water exhales by the stomas, leaving the nu-
tritive particles which it held in solution deposited in thc
leaf.
ExIILY.—And pray, what is the proportion of the quan-
tity of water evaporated to the whole quantity absorbed
by the roots 1
Mrs. B.-It varies exceedingly, according as circum-
stances are more or less avourable to evaporation. A plant
can evaporate only in proportion to its absorption: the quan-
tity, therefore, depends not only on the abundance or-defi-
ciency supplied from the soil, but also on the number of
ramifications of the roots; that is to say, of mouths to
Suck up water. On the other hand, these mouths, how-
ever numerous and abundantly supplied, can continue to
receive water only in proportion as the exhalation by the
leaves carries off what has already been taken in, so as
to make room for more. Thus while water enters at one
extremity of the plant, it must find its way out at the
other.
Ewily.—Were you to pour water into a tube closed at
the opposite end, it would soon be filled, and, though you
continued to pºur, it would receive no more, and the wa-
68 ON SAP.
ter would flow over; but if you opened the closed end,
you might pour in at one end as fast as it flowed out at
the other. But what is it that promotes the flowing out, or,
in other words, the evaporation, of the water by the
lcaves 7
MRs. B.-The most essential circumstance is light.
CARolix.E.-You surprise me : I should have thought
that heat would have been more necessary than light to
produce evaporation.
Mrs. B.-Heat augments it mechanically; but without
light no exhalation from the leaves will take place; and
it will even be inconsiderable, unless the sun's rays fall
upon the plant.
CARollix E.—Is it not very singular that light should be
most favourable to the ascension of the sap which passes
through the alburnum, while heat is most congenial to
that which rises through the centre of the stem What
is the reason of this difference 7 For both saps, I con-
clude, must be of the same nature, since the spongioles
cannot choose, but must suck up whatever is sufficiently
fluid to enter their pores 1
MRs. B.—Being derived from the same source, they
were, no doubt, originally of the same nature; but when
separated into different channels a difference arises : the
nursling sap, we have concluded, undergoes a preparation
in its passage towards the buds, and their expansion, pro-
duced by heat, is alone required to call it up.
While the sap which passes through the alburnum must
not only throw off a considerable quantity of its water by
the leaves, but also undergo a chemical change, for both
of which processes you will find that the aid of the solar
rays is absolutely required.
Let us first consider the simple evaporation by the
leaves. The quantity of water exhaled by plants, is to
that which they absorb generally in the proportion of two
to three ; one third only, therefore, remains in the plant.
and becomes a part of its substance; the rest may be
considered simply as a vehicle which Nature had em-
ployed to convey a due quantity of nourishment into the
plant, and which, after having deposited its cargo, disap-
pcars.
UN SAP. 69
EMILY.—Is the water then which is evaporated per-
fectly pure ?
MRs. B.-It does not contain above a ten-millionth
part of the foreign matter which it held in solution when
absorbed,—a very trifling per centage for the expenses
of freight.
This exhalation is not visible, because the water is so
minutely divided as to be dissolved by the atmosphere as
soon as it comes in contact with it.
CARoll NE.-It may then be compared to our insensible
perspiration.
MRs. B.-True ; and it is called by many botanists
the perspiration of plants, and it sometimes happens (as
is the case also with animal perspiration) that it becomes
sensible. This occurs only in plants whose leaves have
simple ribs uniting at a point at the extremity of the leaf.
The sap is accumulated by the absorption of the roots
during the night, and that portion of it which is destined
to be evaporated flows towards this sole aperture, and
may be seen there in the form of a minute drop, if ob-
served before sunrise, for it is reduced to vapour by the
first solar rays; the subsequent evaporation being equal
to the absorption, no accumulation takes place, and no
fluid is perceptible. . This effect may be seen on the
leaves of corn, which, with all the gramineous family,
have simple ribs.
CAROLINE.-Plants, then, must increase in weight du-
ring the night, since they absorb by the roots without ex-
haling by the stomas :
MRs. B.-They do so; and whenever, through any
accidental cause, the stomas are obstructed or diseased,
the plant becomes dropsical, from the accumulation of
the water it has taken in and cannot discharge. Plants
;Irowing in vases in a room are very subject to this ma-
'udy, owing to their not having sufficient light to evapo-
rate freely. º
Pºrky.-Yet if you expose a nos. gay in a room to
the sun's rays, it withers.
Mº". B.-Bocause the sun produces a degree of eva-
P" which the poor mutilated flowers are unable tº
70 ON SAP.
support; for though the stalks may be immersed in wa-
ter, the organs of absorption are wanting, and the quan-
tity of water they suck up quite inadequate to the evapo-
ration. Since, therefore, you have deprived them of the
power of absorption. you must diminish, at least, that of
exhalation, and, by keeping them in some degree of ob-
scurity, endeavour to preserve the sap which they already
COntal Il.
EMILY.—I should be curious to know what quantity of
water a plant exhales in a day.
Mrs. B.-It has been ascertained by Mr. Hales, that
a full-blown helianthus, or sunflower, placed under ad-
vantageous circumstance in regard to light and tempera-
ture, evaporated twenty ounces of water per day, which
is seventeen times more than that evaporated by a man,
supposing their surfaces equal. This experiment was
made by weighing, first, the water in the vase in which
the sunflower was placed, then the plant itself; and,
after due time being given to the experiment, the water
and the plant were again weighed. The plant had ab.
sorbed as much water as the vase had lost; but it was
not found to have increased in weight so much as the
water in the vase had diminished by twenty ounces,
which affords a conclusive proof that these twenty ounces
had been evaporated. Of course, suitable precautions
had been taken in order to prevent any immediate eva-
poration from the water contained in the vase. Fleshy
fruits, such as apples, plums, peaches, &c. have few or
no pores: they therefore retain the mois ure they receive
from the sap, which enables them to remain long on the
tree, after coming to a state of maturity, without drying
up and withering. While dry fruits, such as peas or
beans, wither in consequence of the number of their
pores by which they exhale moisture. There is the
same difference between thick fleshy leaves, such as
those of the cactus and other succulent plants, and dry
leaves, such as those of the pine and the fir, which are at
the opposite extremity of the scale; common leaves bear
a medium, between the two, but, in the same space in
which a common leaf contains six or seven stomas, the
leaf of a pine has sixty or seventy.
ON SAP. 71
ExILY.—Aquatic plants which live wholly under water,
you told us were not provided with stomas; but now that
I comprehend the nature of their functions, I do not un-
derstand why the plants should not derive benefit from
them: for while the roots absorbed the water holding in-
gredients in solution, the stomas would evaporate it in a
pure state, leaving all its riches behind.
Mrs. B.—The plant has not power to exhale water
into water: it requires the assistance of the air to dis-
solve it and carry it off. Those aquatic plants which rise
to the surface, are abundantly furnished with stomas to
disburden themselves of their excessive supply of water.
Let us now turn our attention to the nature of the sap
which remains in the leaf, after having disengaged its
Superfluous moisture. It consists of about one-third of
the water originally absorbed by the roots, but augmented
and enriched by the acquisition of all the nutritive parti.
cles which the evaporated water has deposited.
CARo1.1NE.—In this state it is certainly better calculated
to nourish the plant; and from this ample store I suppose
the various organs select and assimilate the food they
each require.
Mrs. B.-It is true that every organ performs a chemi-
eal change on that part of the sap which it assimilates to
its own substance ; but the sap previously undergoes a
general change, in some measure analogous to that which
the blood undergoes in the lungs, to prepare it for as-
similation. This operation is also performed in the
leaves, which may be considered as the laboratory in
which the sap is submitted to a regular chemical pro-
CCSS,
Exilly.—This, indeed, bears a very striking resem-
blance to the chyle, which is the sap of animals, and
which is converted into blood, fitted to go through the
general circulation, and nourish the several parts of the
body.”
Mrs. B.-The analogy is perhaps even stronger than
you imagine; for this process, which in animals is per-
formed by means of breathing atmospherical air, in ve.
* Sec Conversations on Chemistry, vol. ii. p. 284.
72 ON SAP,
getables is performed by the same air acting on the sap
when it comes in contact with it at the stomas : the leaves
may therefore be considered as the lungs or organs of
respiration of plants.
ExIILY.—How curious ! their stomas then are so many
little breathing mouths. And does the oxygen of the at-
mospherical air carry off carbon from the sap, as it does
from the chyle
MRs. B.-On the contrary, carbon or charcoal is the
principal ingredient of wood and of all vegetable mat-
ters: the object to be aimed at is therefore to increase,
instead of to diminish, the quantity contained in the sap ;
and the chemical process to which this fluid is submitted
in the leaves, though analogous to that performed by the
lungs, so far as it prepares the sap for being assimilated
to the plant, is rather opposed to it, so far as regards its
chemical results.
We animals, the most favoured part of the creation,
endowed with the faculty of locomotion, require to be of
a lighter structure than our tough woody neighbours who
are attached to the soil : and, in order to move about with
facility, it is necessary for us to disencumber ourselves
of part of the carbon we consume in feeding on vegeta-
bles; and a man you know, exhales in breathing no less
than 11 oz. of charcoal per day; while the vegetable
kingdom, far from suffering from excess of carbon, re-
quires its store to be augmented.
EMILY.-Ah! this is what I have heard spoken of as
one of the most beautiful dispensations of Providence :
the vegetable creation purifies the atmosphere, by absorb-
ing the carbon with which it has been contaminated by
the breath of animals.
MRs. B.—Just so; but let us examine these wonders a
little more narrowly, and trace the steps by which they
were brought to light.
Mr. Sennebier covered a plant which was growing in
a pot of earth with a glass bell full of water; and, in the
course of a few hours, found a quantity of air within the
bell. Whence came this air 1 Did it proceed from the
plant or the water in which it grew He repeated the
(DN SAP, 7.}
*Xperiment with water which had been boiled, for the
Purpose of depriving it of its air, and in this instance no
air was produced in the bell.
CARoline.—Of what nature was this airl
MRs. B.—Dr. Priestly ascertained that it consisted of
oxygen gas, and conceived that it was produced by the
decomposition of the water, which, you know, is com-
posed of oxygen and hydrogen; but then he could not
understand why boiled or distilled water, which contains
as much oxygen as rain or spring water in their natural
state, should not produce this air in the glass bell.
At length Mr. Sennebier, in the prosecution of his ex-
periments, discovered the mysterious origin of this air to
be in the carbonic acid, which water, in a natural state.
always contains. I trust that you have not so far forgot-
ten your lessons of chemistry, as not to recollect that car-
bonic acid is composed of oxygen and carbon : the plant
absorbs this gaseous acid. It is decomposed in the leaves
by the sun's rays: the carbon, which it is essential to the
plant to retain, is deposited; and within it the oxygen.
which it does not require, flies off by the stomas.
CARolisE.—Then the little vegetable mouths breathe
out pure oxygen, and retain the carbon : this is just the
reverse of the operation performed in the lungs.
Mes. B.-You may prove this by a very neat experi-
ment. Place two glass jars over the same water-bath.
with a means of communication through the water; fill
one of them with carbonic acid, and put a sprig of mint
in the other. After some time, a vacuum will be pro-
duced in the upper part of the jar of carbonic acid; and
a quantity of oxygen gas, corresponding exactly to the
quantity of carbonic acid which has disappeared, will be
found in the jar containing the sprig of mint. And this
cannot be accounted for otherwise than by supposing.
that the carbonic acid has been absorbed by the mint,
decomposed by its leaves, the carbon retained, and the
oxygen evaporated.
M. de Saussure has succeeded in measuring the quan-
tity of carbon which plants thus acquire. He transplanted
fourteen periwinkles into vases, seven of which he wa-
7
74 ON SAP,
tered with distilled water, and the remaining seven with
water in its natural state. After some days he analysed
these plants, and found that the former had not made any
acquisition of carbon, while the latter had acquired a
considerable addition of that substance; their wood being
one-sixth heavier than that of the former.
EMILY.-And the periwinkles, which had augmented
in weight, had, I suppose, alone given out oxygen by their
stonla S.
MRs. B.-No doubt; but, in making these experiments.
attention must be paid to expose the plants, not only to
broad daylight, but, if possible, to the full force of the
sun's rays; for the solar light is absolutely necessary to
the process of decomposing the carbonic acid. During
the night the vegetable laboratory is employed in a very .
different process; for, in the dark, plants absorb instead
of exhaling oxygen.
CARoline.—You alarm me, Mrs. B. : this is a sort of
Penelope's labour, to destroy during the night the work
done in the day. And how is the atmosphere to be puri-
fied by these means ?
Mrs. B.—It is true that this apparent inconsistency re-
quires some explanation. You must observe, that the
solid nutritive particles dissolved in the sap, whether of
animal or vegetable origin, are combined with a conside-
rable quantity of carbon. The sap therefore contains
carbon in two states: in the one gaseous, combined with
oxygen, and mixed with the water of the sap ; in the
other combined with different solid ingredients, but dis.
solved in the water of the sap. The carbonic acid, we
have already observed, is decomposed in the leaves, the
carbon is retained, and the oxygen thrown off; but what
becomes of the carbon contained in the animal and vege-
table matter which the sap holds in solution ?
CARoline.—I suppose it is assimilated to the substance
of the plant, together with the other nutritive ingredients
which the sap holds in solution.
Mrs. B.—No, that cannot be ; for, in order to render
carbon fit to be assimilated, it appears to be necessary that
ON SAP. 75
it should previously be combined with oxygen, and after.
wards separated from it.
CARolin E.-Is there not something paradoxical in this?
How can it be necessary that the carbon should be com.
bined with oxygen, merely for the purpose of being sepa-
rated from it?
Mrs. B.-It is very possible that this chemical process
may produce a more minute subdivision of the particles
than any mechanical operation could effect, and thus pre-
pare it for being assimilated to the plant.
CARoll NE.-Oh, then, now I guess it. During the
night the leaves absorb oxygen, to combine with this car-
bon, and convert it into carbonic acid; and, when the sun
rises, this acid is decomposed, the carbon deposited in a
state fit to be assimilated, and the oxygen escapes.
Mrs. B.-You are right; and as the decomposition of
the carbonic acid, which existed in that state in the sap,
takes place at the same time, these two operations, being
both similar and simultaneous, are confounded together.
But, so far as regards the purification of the atmosphere,
it is necessary to distinguish them : for, in the first in-
stance, the oxygen exhaled is a mere restoration to the
atmosphere of oxygen which had been taken from it du-
ring the night; while, in the latter, the oxygen evolved.
being drawn from the soil with the sap, is so much clear
gain to the atmosphere.
CARoll NE.—Well, I breathe freely again, since I know
that the atmosphere positively-acquires oxygen from the
vegetable kingdom. The portion absorbed during the
night, I suppose, is but inconsiderable.
MRs. B.-Not so trifling as you seem to imagine; but,
since the whole quantity is restored to the atmosphere du.
ring the day, you need not apprehend any dangerous re-
suits from its abundance. The Stapadra, the plant which
absorbs least, takes in a quantity nearly equal to its own
volume during a night; and the apricot-tree, which is at
the other extremity of the scale, absorbs eight times its
own volume of oxygen gas.
Succulent plants absorb the least, having the fewest
stomas; and, after them, plants which grow in marshes:
76 ()N S.A.P.
then evergreens; and, finally, those plants which shed
their leaves in autumn absorb the greatest quantity.
EMILY.—It is this, I suppose, which renders it unwhole-
some to keep plants in a bedchamber?
MRs. B.-It is; but, besides this, I should tell you
that those parts of plants which are not green, such as
the brown stems and branches of a tree, and also the
flowers, absorb oxygen both night and day, but in such
very minute quantities, as not sensibly to deteriorate the
ill I’, "
Let me hear, now, if you can recapitulate the substance
of our conversation.
Ewily.—The sap rises in plants through two different
channels: that which is destined for the nourishment of
buds, in shoots of the first year, passes near the pith, and
is thence conveyed by appropriate vessels through the
wood to the buds; that which is to feed the plant in ge-
neral, rises through the alburnum, and is elaborated in
the leaves.
Mrs. B.-Very well; and in what does this elabora-
tion consist, Caroline !
CARolix E.—In preparing the sap to be assimilated to
the plant by evaporating great part of the water, and in-
creasing the quantity of carbon. The sap contains car-
bon in two states: first, in that of carbonic acid; se-
condly, combined in animal and vegetable matter. In
the first state the sun's rays decompose the acid, the car-
hon is deposited, and the oxygen which flies off purifies
ſhe atmosphere; in the second state, oxygen is absorbed
during the night, and combines with the carbon, with
which it forms carbonic acid; this, during the day, is de-
composed, and the oxygen restored to the atmosphere.
Thus vegetation serves as a counterpoise to the delete-
rious effect of the respiration of animals.
EMII Y.—And should we not add to the contamination
ºf the air by combustion, Mrs. B. 1 for oxygen is also ab-
Sorbed in that process.
C Rolf N.E.—The air of a forest must then be much
more wholesome than that of a town, where so many hu-
man beings and animals are continually breathing out
ON CAMBIUM. 77
carbonic acid, and where such numberless combustions
are robbing the atmosphere of oxygen.
Mrs. B.-No; the constant motion of the air so ra.
pidly restores the equilibrium, that it has been found, by
the most accurate chemical experiments, that the air of
a crowded city contained precisely the same quantity of
oxygen as the finest air of the country. I do not mean
to say that the atmosphere is not more impure and un-
wholesome in a large town; but this arises from the
smoke, and variety of exhalations, which do not circulate
So rapidly as the oxygen gas.
The air in a forest is, on the other hand, far from being
considered as healthy; the trees impede the circulation
more than the houses in a town, the latter being, in some
measure, ventilated by the currents of air which flow
through the streets.
CARolisE.—But, then, consider the pure breath of the
green leaves in a forest.
MRs. B.-The exhalations arising from the stagnant
waters, and the putrefaction of the dead leaves which
remain floating in the confined air, more than counterba-
lance that advantage, and render a dense forest an un-
wholesome spot to inhabit.
CONVERSATION VI.
ON CAMBIUM, AND THE PECULIAR JUICES OF
PLANTS,
Mrs. B.-Having traced the sap in its ascent to the
extremity of the leaves, and converted it, by the changes
it undergoes in that chemical laboratory, into an homoge-
nous liquid adapted to the nourishment of the plant; we
must now, following it in its descent, observe in what
manner it performs this office.
The sap, thus changed, assumes the name of Cam.
bium or returning sap, and passes into another system of
vessels which convey it downwards, chiefly through the
liber, or most internal layer of bark, and a small portion
7*
75 ON CAMBIUM,
º
through the alburnum, or young wood; and, as it tra-
verses the several organs, it deposits in each the various
matters requisite for their sustenance.


CAROLINE.—Having compared the ascending sap to
chyle, Mrs. B., we may find a still greater analogy be-
tween the cambium and blood, into j chyle is con-
verted, after having passed through the heart and lungs,
and been rendered fit to nourish the animal frame.
MRs. B.—We have already observed, that the chemi-
cal changes which take place in the leaves, in order to
convert the sap into cambium, are in many respects ana-
logous to those which take place in the heart and lungs,
in order to convert the chyle into blood.
Exſily.—True: in both cases the atmosphere is the
agent; with this difference, however, that it carries off
carbon from the animal system, while it is the means of
accumulating carbon in that of vegetables.
CARoline.—But if the cambium descends through the
liber, how does it find its way in endogenous plants, which
have no bark?
MRs. B.-Its passage in monocotyledons has not been
well ascertained. It is probable, that the fibres of the
wood are the medium through which the sap both ascends
and descends; but you may recollect that it is not well
ascertained, whether the ascending sap rises through the
vascular or cellular system, or through the interstices be-
tween them; and the vessels which convey the descend-
ing sap being so minute, as barely to be discernible by
the aid of a microscope, it is impossible to examine them
with accuracy. Besides which a still greater difficulty
attaches to the investigation of the vessels of endogenous
plants: those which grow in our climates being too small
to enable them to acquire that degree of vigour which is
requisite for a complete developement of their organs.
CARoline.—We shall not have the same difficulty to
account for the descent of the cambium, as we have had
for the ascent of the sap; since it obeys the laws of gra-
vity and descends by its own weight.
MRS. B.-That is a general cause of the descent of
cambium, no doubt; but in the weepng willow, and many
Q ON CAMBIUM, 79
other trees whose branches are pending, some additional
cause is required to produce the motion of the cambium,
since it must rise to return into the stem. Is has been
ascertained that agitation facilitates and accelerates this
motion, and consequently increases the vigour of vegeta-
tion; for the more rapidly this nutritive fluid circulates
through the several organs, the more frequently it will
deposit its nutritive particles in them. Mr. Knight has
made a variety of interesting experiments on this subject.
He confined both the stem and branches of a tree, in such
a manner that it could not be moved by the wind. The
plant became feeble, and its growth much inferior to that
of a similar tree, growing in a natural state. Mr. Knight
confined another tree, so that it could be moved only by
the north and south winds, and obtained the singular re-
sult of an oval stem; the sides accessible to the wind
growing more vigorously than those sheltered from its in-
fluence. Every species of restraint, and especially such
as tends to render plants motionless, impedes their growth.
Stakes by which young trees are propped, nailing them to
walls or trellises, greenhouses, or confined situations
where this salutary air has not free access, check and in-
jure the vigour of vegetation, and render plants diminu-
tive and weakly.
CARol.1NE.—But if young trees were unsupported,
they would in all probability be blown down by the first
violent wind.
MRS. B.-The stake, it is true, is often necessary; but
then it must be considered as a necessary evil, and re-
membered that, whenever it can be avoided, the plant
will thrive better without it. It should never be fastened
so tightly as to prevent all motion, for the exercise which
the wind gives to young trees is no less salutary than that
which a mother gives to her infant; but it is true that the
wind is often a rough nurse, over whom it is prudent to
Keep a watchful eye.
CARo11NE.—Then nailing fruit-trees against walls must
be prejudicial to their growth :
MRs. B.—No doubt; but the advantages resulting from
the shelter afforded by walls and the heat reflected by
80 ON CAMBIUM.
them, more than compensate for the bad effects of con-
finement—for such fruits, at least, as require a higher
temperature to ripen them than is to be met with in our
climate ; but, when the temperature is genial to the plant,
standard trees, growing freely in their natural state, pro-
duce the finest fruits. Green-houses and hot-houses,
however confined, are asylums necessary in winter for
the culture of plants of a warmer climate ; for though
gentle breezes may be beneficial to fan delicate plants,
we must shelter them from the inclemency of boisterous
winds.
The cambium, we have observed, descends almost
wholly through the liber, or most internal and youngest
layer of the bark; if, therefore, you cut a ring com-
pletely through the bark, this fluid will be arrested in its
course, and, accumulating around the upper edge of the
intersected bark, cause an annular protuberance. The
descent of the cambium thus being obstructed, it will ac-
cumulate in that part of the tree above the intersection,
aflord it a superabundance of nourishinent, creating a
proportional vigour of vegetation, and a corresponding
excellence and profusion of produce.
Exilly.—Would it not then be a good mode of impro-
ving the produce of fruit trees?
Mrs. B.-This operation, which is called ringing, has
been tried on the branches of fruit trees, and, I understand,
often with success; but I should conceive that the tree
must be ultimately injured by the operation; for, if you
confine to one part of a plant the food which was destined
for the nourishment of the whole, you interfere with the
order of that wisest and best of agriculturists—Nature.
When interrupted, however, in her original course, she is
fertile in expedients to accomplish by collateral means her
destined purposes. I observed that some small portion
of the cambium descended through the alburnum, which
is contiguous to the liber. When the annular section is
made on a branch, a much more considerable quantity
forces its passage through this channel, and, by affording
the young wood an unusual supply of nourishment, ren.
ders it harder and heavier below than above the intersec-
tion.
ON C.AMBI U. M. 81
CARoLINE.-But if the vegetation of the tree above
the annular section is improved, and the wood beneath
it better nourished, what part of the plant suffers by this
operation ?
Mrs. B.-Not any part during the season the annular
section is made ; the evil is reserved for a later period, as
I shall explain to you.
The cambium being thus diverted from its course, the
greater part being forcibly detained above the annular
section, and what little makes its escape descending
through another channel, the bark is wholly deprived of
its natural sustenance ; the consequence of which is, that
the new layers, both of alburnum and of liber, which should
be annually produced by the descent of the cambium, are
not formed.
The following season, therefore, the sap, instead of
rising through the soft and tender vessels of the newly-
formed alburnum, must ascend through the alburnum of
the preceding year, under the additional disadvantage of
its being unusually hardened by the superabundant quan-
tity of nourishment it has received.
This artificial mode of rendering alburnum hard and ma-
ture, suggested the idea of stripping timber-trees of their
bark a year or two previous to their being cut down, in order
to harden the young external layers of wood, by forcing the
whole of the cambium to find a passage through them, and
thus convert the alburnum into perfect wood before the
natural period. The experiment, when first made, ap-
peared to answer the most sanguine expectations. The
cambium, instead of forming new layers of tender wood
under shelter of the bark, forced its way through the al-
burnum, giving it in one season the hardness and consist-
ence of perfect wood. But it was afterwards discovered
that the wood thus artificially matured, by being stripped
of its bark, and exposed naked and defenceless to the in-
clemency of the weather, to the encroachment of lichens
and creeping plants, and to the attacks of insects and rep-
tiles ; receives injuries, which more than counterbalance
the advantages of a precocious naturity, and renders it
totally unfit for building.
Let us now turn our attention to the composition of th
82 ON CAMBIUM.
cambium, which subsequently becomes a component part
of the plant.
We have observed, that about two thirds of the water
absorbed by the roots is evaporated by the leaves, one-
third only remaining in the plant. This latter portion ex-
ists in vegetables in two states: in the one it retains its li-
quid form; in the other it is decomposed, and enters into
a chemical combinaiion with various parts of the plant,
so as to be identified with its solid tissue, and in such a
manner that desiccation will not make it reappear.
ExIILY.—But by a chemical analysis would you not
discover it?
MRs. B.-No; because it no longer exists in the form of
water, but is resolved into its constituent elements, oxygen
and hydrogen.” I trust you recollect that water is a
combination of these two principles.
M. de Saussure weighed the water with which he
watered a plant; and, after the most careful investigation
by mechanical means, both by preserving the water eva-
porated, and obtaining that which remained in the plant
by desiccation, he could not discover above five-sixths of
the water he had given to the plant.
EMILY.—And is it known under what form this sixth
portion of water exists, in its new combinations in the
plant?
Mrs. B.—The oils and resins with which plants abound
contain a very large proportion of hydrogen. There are
other vegetable substances which abound with oxygen ;
the water, therefore, which so totally disappears, is doubt.
less resolved into its two constituents, oxygen and hydro-
gen, supplying the oils and resins, and the other juices,
with such proportions of these elements as they respect-
ively require.
Carbon is obtained by plants from three different sour-
ces: from carbonic acid contained in the sap ; from ani-
mal and vegetable matter dissolved in that fluid; and from
the atmosphere. g
CARoLINE.-Having so many means of procuring car-
bon, no wonder that plants should lay in so large a stock.
* See Conversations on Chemistry, vol. i. p. 227.
ON CAMBIUM. 83
Mrs. B.-What part of a plant would you imagine
contained the most carbon 1
CARoline.—I should think the wood, which burns so
well because it consists almost wholly of charcoal.
EMILY.—And yet the leaves in which the carbon is de-
posited, when separated from the oxygen, should contain
more of that ingredient than the wood.
CARoline.—In that case leaves should be used for fuel
in preference to wood.
MRs. B.-Emily is right : the green parts of plants
contain the most carbon; and dry leaves make an excel-
lent combustible, but they are too large in volume to form
a convenient one.
After the leaves, the bark, especially when green,
abounds most with carbon ; and, lastly, the wood : the
alburnum or white wood contains the least.
CARolf NE.-Green wood then should be most combus-
tible ; and yet it is noted tor burning badly.
Mrs. B.-Py green wood is commonly meant wood not
sufficiently dried. Whatever quantity of carbon wood
contains, it cannot prove a good combustible, unless the
water, and other juices injurious to combustion, be first
evaporated.
The alburnum when well dried, burns briskly, because
it contains a greater quantity of hydrogen than perfect
wood; and it is the combustion of hydrogen, you may
recollect, which produces flame : but, owing to its defi-
ciency of carbon, alburnum gives out less heat.
The ascending sap, we have observed, contains also a
great variety of earthy and alkaline particles; such as
magnesia, lime, silex, potash, and soda. When the eva-
poration from the leaves takes place, these bodies are de-
posited, and become constituent parts of the cambium,
and are thus conveyed to their several destinations.
The most soluble of the earthy salts, such as lime and
magnesia, are naturally most abundant in the sap ; and
when a plant is burnt, the earths, being incombustible,
form the materials which constitute its ashes.
The alkaline salts, potash and soda, being also of a so-
luble nature, are conveyed in considerable quantities into
84 ÖN CAMIBIU M.
the sap ; when this undergoes evaporation, a large portion
of these salts is deposited in the leaves, the rest remains
in solution in the cambium, incorporates with the plant,
and, after combustion, may be discovered in its ashes.
The silecious particles contained in the plant being, on
the other hand, nearly insoluble, enter very little into the
composition of the cambium, the greater part remaining
in the leaves, where it has been deposited by the evapora.
ting sap ; and the fall of the leaf is attributed to the accu-
mulation of this hard earthy matter, which in the course
of time clogs and indurates their vessels, so as to render
them impervious to the juices requisite to their vegetation.
The vessels composing the petiole, in which they are so
closely bound together, are more especially liable to suffer
from these obstructions: unable any longer to transmit
nourishment to the leaf, the petiole dries, withers, and
falls off; and the plant is thus disburdened of a useless
substance, the accumulation of which would be prejudi-
“ial to its growth.
CARolliSE.—It must be confessed, that it is rather a
serious remedy to destroy the organ, in order to get rid
of the inconvenience with which it is afflicted.
MRs. B.-You must consider, that when Nature con-
structed these organs in so frail and delicate a manner, it
was with the intention that they should be annually re-
newed: it becomes expedient, therefore, to get rid of the
old leaves, in order to make way for the new ones.
Azote, an ingredient chiefly of the animal kingdom, is
to be found also, in very small quantities, in vegetables:
they obtain it both from the atmosphere, of which it
forms the chief constituent part, and from the animal
matter of manure.
From the cambium, with all the component parts of
which you are now acquainted, a great number of dif.
ferent juices are secreted, such as oil, resins, gum, &c.
CARoLINE.-Just as tears and saliva are, in the animal
economy, secreted from the blood.
MRs. B.—There is, it is true, a considerable analogy
between the animal and vegetable secretions: they are
both drawn from the general nutritive fluid, and each by
ON CAMIBIUM. S5
the means of glands; but, owing to the extreme minute-
ness of the organs of plants, the vegetable anatomy is
very much behind that of the animal kingdom.
EMILY.—In small herbs this must necessarily be the
case; but in large forest-trees, I should have supposed
that the organs, when fully developed, would have been
of greater magnitude than those of animals.
MRs. B.-No ; the organs of the oak are not larger
than those of the family of mosses. Nor is this singu-
lar, if you consider that the leaves and fruit of forest-
trees are not, in any respect, proportioned to the size of
the plant:-you do not forget the fable of the Pumpkin
and the Oak. Every leaf and every flower must con-
tain a system of organs, adapted to the various opera-
tions it has to perform, without any reference to the
general size of the plant. In the animal economy we are
still unable to discover the mode in which the glands
elaborate their secretions from the blood: how much
less, then, can we expect to penetrate the secret, in a
system where the organs themselves are frequently so
minute as to elude our sight, the largest not being more
than one-twentieth of a line in diameter, and there are
some, so small as not to exceed the one hundred and
fiftieth part of a line in dimension 1
Many ingenious hypotheses have been proposed to
account for the secretory action of the glands, both in the
animal and vegetable economy, but none have hitherto
proved satisfactory. That which appears least objec-
tionable, is the agency of electricity; but it must be
owned that the chief argument in favour of this agent is,
that we are not yet sufficiently acquainted with its
powers to prove the hypothesis which rests upon it to be
(*rrolléOUIS,
The chemistry of vegetables, on the other hand, is
more advanced than that of the animal kingdom; be-
cause the great and mysterious secret, life, performs a
less important part in the vegetable than in the animal
“conomy.
The secretions separated from the cambium by the
glands are of two descriptions: the one, destined to re-
8
86 ON CAMBIUM.
main in the plant, is distinguished by the name of internal
secretions, and is elaborated by glands of a cellular form;
the other, intended to be conveyed out of the plant as
useless or detrimental to it, is for this purpose secreted
by glands of a vascular form.
The internal secretions are milk, resins, gums, gum
resins, manna, essential oils, and fixed oils.
EMILY.-These are substances with which we are in
some measure acquainted, as I believe you explained
their chemical composition in our Conversations on Che.
mistry.
Mrs. B.-True ; but we are now to examine them
rather in a different point of view; and I do not think I
then mentioned the secretion of vegetable milk. There
are three species of this fluid : the first is that which
contains opium, and is extracted from the juice of pop-
pies, lettuces, and some other plants; it is almost always
white, but sometimes assumes a reddish or yellowish tint.
The second contains caoutchouc, or elastic gum ;
which, however different in appearance in the artificial
state in which we are acquainted with it, is naturally
white and liquid.
It is obtained from several different species of trees in
tropical climates, but principally from that which bears
the name of Hevea.
When an incision is made in the stem, it flows from
the wound, and is collected on the surface of small
moulds of clay in the form of bottles, to which, being of
a glutinous nature, it adheres. It acquires consistence
and blackens in drying, and, when the coating of ca-
outchouc is of a sufficient thickness, it is beaten to pul-
verise the mould, which is then shaken out.
The third species of vegetable milk resembles that of
the cow, and is the produce of a tree in America, thence
called the cow-tree. Mr. Humboldt informs us, that it
grows in rocky and unfruitful districts, little calculated
for the pasturage of cattle. On the barren side of a rock
it rises with coriaceous and dry leaves, which are, during
many months of the year, not moistened by a single
shower. The branches appear dead and dry; but.
ON CAMBIUM. 87
when the trunk is pierced, there flows from it a sweet
and nourishing milk. At sunrise, this vegetable fountain
is most abundant. The natives are seen hastening from
all quarters, furnished with large bowls to receive the
milk, which grows yellow, and thickens at the surface.
This tree is of the family of the Sapoteae.
CARol.INE.--What a delightful resource it must be to
the people of that country, who may repose beneath its
shade, while they refresh themselves with the grateful
beverage it produces ! Does it also yield fruit
MRs. B.-Every tree yields fruit of some kind, other.
wise it could not continue its species; but that of the
cow-tree is as yet unknown.
Resins are volatile oils, peculiarly modified by the ac-
tion of oxygen. Pitch, tar, and turpentine are the most
common and the most useful juices of this description:
they exude from the pine and fir trees, and are of a thick
viscous consistence. Copal, mastic, and frankincense
are resins of a more refined nature: the two former, dis-
solved in oil, form excellent varnishes; and frankincense.
you know, is the perfume burnt in all the Catholic church-
es. The resinous juices flow always in a descending
direction: when an incision is made in a tree which
yields them, they trickle from the upper edge of the
wound.
Gum is a mucilaginous secretion, common to all legu-
minous plants, and to a great number of trees bearing
stone-fruits, such as the cherry, the peach, and the apri-
cot: whenever an accidental fissure is made in the stem.
it exudes from it.
Gum-arabic is obtained from the acacia of Arabia by
incisions made in the stem.
Gum-tragacanth exudes naturally from the stem of
Astragalus. This secretion, which accumulates during
the night, when little or no evaporation, takes place,
swells the wood which presses against the bark, and,
this dry coating not being susceptible of a similar disten.
tion, the gum forces its way through it.
Gum-resins appear to be a mixture of the two vegeta-
ble products from which their name is derived, and are
common to all umbelliferous plants.
SS ON CAMIBIUM.
Manna is a saccharine secretion, which abounds in the
small-leaved ash of Calabria. It is to be found also, in
Smaller quantities, in several other trees, such as the larch
and the willow.
The essential or volatile oils bear a strong resemblance
to resins; they are enclosed in small vesicles, whence
they are extracted by pressure. They are imprisoned,
in this manner, in the rind of the orange and the bark of
the cinnamon-tree, in the wood of the sandal-tree, and in
a great variety of leaves, such as those of the gerranium
and the orange, and in ſlowers of almost every descrip-
tion. In a word, there is scarcely any part of a plant
from which essential oil may not be extracted, excepting
the seed, from which it is absolutely excluded.
Fixed oils, on the contrary, are almost exclusively
contained in the seed, where they constitute the most ap-
propriate nourishment for the embryo plant. There is,
I believe, but one exception to this rule, the olive, where
the oil abounds not only in the seed, but also in the pulp
of the fruit, whence it is expressed to supply our tables.
or for the purpose of combustion. Nut-oil, linseed-oil,
and all the fixed oils, are not, like the essential oils, en-
closed in appropriate vessels, but are lodged in every in-
terstice of the seed. We shall speak more fully of this
when we come to examine the organization of this assy-
lum of the embryo plant.
Let us now proceed to the excretory secretions: they
are of much less importance than the preceding, and
consist chiefly of vapours and gases exhaled from flowers.
Among these we distinguish the vapour of the Fraxinella,
which is elaborated by glands sufficiently large to be vi-
sible, and is very combustible.
ExILY.-I recollect having seen it burn, by approach-
ing a taper to it; but is not this vapour similar to the ex-
halations of the odour of plants?
Mrs. B.-No; the odours of plants are undoubtedly
an excretory secretion, but are not generally of a com-
bustible nature. They are of various descriptions, but it
is difficult to determine in what manner to class them, as
they affect the olfactory nerves of different people in so
different a manner; they have been attempted to be dis.
ON CAMBIUM. 89
tinguished by the name of aromatic, stimulating, pene-
trating, sweet. Flowers, with some few exceptions,
(such, for instance, as the rose and the violet,) exhale
their perfume only as long as the plant is living; that
which proceeds from the bark, or other parts of the plant,
continues to be emitted after death.
Flowers having an ambrosial smell, exhale it only in
the evening, after sunset; those which have the odour of
musk are always of a yellowish purple colour, and of a
dull appearance, corresponding, it is said, with the delete-
rious nature of their perfume.
The smell of flowers, in general, is considered to be
more insalubrious to a person sleeping than awake.
Whether it be, that, in the latter case, the animal frame
has a more energetic power of resistance to deleterious
effects, or from some other cause, is not ascertained.
EMILY.—May not this difference arise from plants giv-
ing out oxygen during the day, and absorbing it during
the night?
MBs. B.-No ; the spasmodic effect produced on the
nervous system by the perfume of flowers is quite inde-
pendent of those operations; and it is sleeping or wa-
king, whether in the daytime or the night, that the diffe-
rence I mentioned has been observed.
Besides the water which plants exhale from the leaves,
there are several peculiar juices elaborated by glands
situated on the surface of the leaves. These are fur-
nished with hairs, at either the point or base of which
they grow, and may be compared to the hairs which grow
at the orifice of the pores of our skin.
ExILY.—How extremely minute must those glands be
which can be supported on so slender and frail a stem'
MRs. B.-You may thence form some idea of the di-
minutive size of the vegetable organs in general. When
the secretory gland is situated on the summit of the hair,
the liquid it secretes is of an innocent nature; when situ-
ated at the base, the secretion is acrid, caustic, and poi-
SOIl ()llS.
CARolix.E.—This is, no doubt, the case with nettles,
S*
90 ON CAMIBIUM.
which pour their poisonous secretions on the skin, and
raise it into blisters.
MRs. B.—The poison must penetrate beneath the cuti-
cle in order to produce this effect; the hair is the instru-
ment which gives the wound, and the poisonous juice is
then poured into it.
ExILY.-This is just like the sting of a serpent, who
inflicts a wound, and then ejects his poison into it. But
what is the reason that nettles do not sting when wetted
with rain
Mrs. B.-Because the hair, when softened by mois-
ture, has not sufficient strength to perforate the skin; and,
unless a puncture be made, the secretion cannot insinu.
ate itself beneath the skin, and no sting is felt. Stinging
plants can also be handled with impunity after death, if
dried; for, though in this case the instrument may be ca-
pable of wounding, the poisonous juice is no longer fluid,
and cannot flow into the puncture.
EMILY.—Then should we not feel the infliction of the
wound, although we might escape the smarting of the
blisters?
MRs. B.-The instrument is so minute and delicate,
that the wound it inflicts would not be felt were the skin
not inflamed and blistered by the poison.
The nectar of flowers, the bloom of fruits, and the vis-
cous coating of aquatic plants, which preserve them from
the element in which they grow, may all be considered
as excretory secretions; but we will postpone their exa-
mination till we enter upon the subject of flowers and
ſruits.
We have now traced the sap, from its first entrance
into the roots, throughout the whole frame of the plant;
we have examined its component parts, the chemical
changes it undergoes in the leaves, its subsequent descent
under the form of cambium, and the various peculiar
juices which are secreted from this nutritive fluid, as it
returns from the extremity of the leaves into the roots.
EMILY.—But is the whole of the sap consumed in the
erformance of these several operations, and does no part
of the cambium return through the roots into the earth?
ON CAMBIUMI. 91
MRs. B.-It is the opinion of M. De Candolle, founded
on experiments he has made on this point, that a small
residue of the cambium exudes from the roots into the
round.
In planting, it has long been observed that trees of a
different species from those which previously occupied
the ground, thrive better than a repetition of those of the
same kind : wl ºnce it is inferred that the exudation of
one species of plant, though it may injure the soil for
other individuals of the same species, may possibly afford
appropriate nourishment for plants of another description.
13ut this is a question we shall refer to at some future pe.
riod.
IIaving now concluded our examination of the struc-
ture of a plant, and of the mode in which it is nourished,
I shall proceed next to observe in what manner it is af.
fected by the external bodies with which it is in contact,
such as light, heat, the atmosphere, the soil, &c. This
will enable you to acquire some information respecting
the culture of plants; and though I do not aim at making
you adepts in agriculture, yet I consider the application
of botany to that science as the most useful and the most
interesting point of view in which it can be studied.
CARo1.1NE.—And it must be much more amusing than
the common mode, of studying the classification of plants.
Mrs. B.-Classification must always be respected in
science. It is impossible to acquire any clear ideas in
any branch of knowledge without its aid; but it is true
that in botany it is sometimes held in too high estimation.
In the eagerness of pursuit, the student is apt to forget
that classification is but the means, not the end to be at-
tained.
M. De Candolle's mode of classification is more sim-
ple than that of any preceding botanist; still you must
expect it to afford you instruction rather than amusement.
I}ut we shall not treat of it till we have examined the va-
rious organs of the flower on which it is founded.
CARo11NE.-And when are we to learn the history of
the flower, Mrs. B. —that part of botany which I once
thought comprised the whole of the science 2
92 ACTION OF LIGHT AND HEAT
Mrs. B.-The flower is the asylum, in which the seed,
destined for the reproduction of the plant, is lodged and
cherished. We shall examine the flower and the seed,
therefore, in immediate succession, when we enter on the
subject of the reproductive powers of plants.
CONVERSATION VII.
ON THE ACTION OF LIGHT AND HEAT ON PLANTS.
Mrs. B.-In examining the effect of external bodies on
plants, we shall begin with light, which may be considered
as acting on them in four different ways. The first rays
of the rising sun seem to awaken the vegetable creation
from its state of repose.
CARolin E.-You do not mean to infer that plants sleep
during the night, Mrs. B.
MRs. B.-I doubt whether the term sleep be literally
appropriate to that state of relaxation and inaction which
appears to afford them repose during that season. The
leaves and flowers usually change their position as soon
as it grows dark; in many plants the leaves drop ; in
others they close, as well as the petals of the flowers, and
are opened by the first rays of the morning sun. The
leaves then recommence their chemical operations, the
spongioles draw up a provision for their labours, every
function which had ceased or diminished during the night
is again renewed, and the whole plant reanimated. It is
this effect, produced by light on plants, which I call being
awakened.
Secondly, the direct rays of the sun are necessary to
onalile plants to decompose carbonic acid gas in any
censible quantities. We have already observed, that in
this process the oxygen of the carbonic acid is exhaled by
the leaves, and the carbon deposited in the plant: now,
it is this deposition which produces their green colour.
Mr. Sennebier is of opinion, that carbon is not positively
black, but of a dark blue colour. The cellular tissue of
plantsis of a yellowish white; consequently, when those

ON PLANTS. 93
iminute blue particles are lodged within the yellow cells.
the combination of the two colours produces green, in
which the blue or yellow tint prevails, in proportion as
the carbon or cellular tissue predominates.
CARoll NE.—That is very curious, and accounts for the
pale delicate tint of the spring verdure, when but a small
quantity of carbon has been deposited in the leaves; and
the deeper shades which plants acquire in summer and
autumn, when they have accumulated a greater stock of
carbon.
But what is it that produces the change of colour at
the fall of the leaf, and, indeed, often takes place previ-
ous to their fall, when some leaves assume a beautiful
red or yellow colour !
MRs. B.—Some ingenious experiments have lately
been made on this subject by Mr. Macaire. He ascer-
tained that, late in autumn, when leaves begin to change
their colour, they absorb oxygen during the night, but
lose the power of giving it out during the day: hence he
infered, that the accumulation of oxygen destroyed the
green colour, and produced the various tints which the
autumnal leaf assumes.
EMILY.—We know the power that oxygen has in
changing the colours of metals; it is not, therefore sur-
prising that it should produce effects somewhat similar on
plants; but if it is oxygen which gives rise to the red and
yellow colour of dying leaves, may it not also be the cause
of the various hues of living flowers ? Mr. Macaire
should have prosecuted his researches to have discovered
this.
Mrs. B.-He did so ; and was led by their result to
think, that it is to the various quantities and modes of
combination of oxygen, that the different colours of ſlow-
ers is to be attributed.
The third mode by which light acts on plants, is by
facilitating, and consequently increasing, their absorbent
powers. The more the cause is augmented, the more
the effect is increased. Tell me now, what do you sup-
pose would be the result of great intensity of light !
PMILY.—To be enabled to answer your question, it
4)4 ACTION OF LIGHT AND HEAT
would be necessary to be acquainted with the plants of
tropical climates, where light as well as heat is so much
stronger than in our latitudes.
CARoll NE.—It would be more easy, in this mountain.
ous country, to study the plants which grow on their sum-
mits, where they are so much more exposed to light than
in the valleys or the plain; and I recollect observing,
that they are generally of a deeper green, which is no
doubt owing to the greater deposition of carbon.
EMILY.—I have remarked, also, how much deeper the
green colour of vegetation is in Italy than in England.
MRs. B.-In the tropical climates this difference is still
more remarkable. But what is very extraordinary, M.
Humboldt met with some green plants, growing in com-
plete darkness, at the bottom of one of the mines of
Freuberg. The mine abounded with hydrogen. Now,
whether this gas be endowed with the power of develo-
ping the green colour, or whether it may enable them to
decompose carbonic acid without the aid of light, is a
problem which we must leave to more able chemists to re.
solve. What increases the difficulty is, that carburetted
hydrogen gas is a poison no less deleterious to plants than
it is to animals.
Another effect of intensity of light, is to render plants
remarkably firm and hard of texture, owing both to the
accumulation of carbon, a body of a compact solid nature,
and to the increased vigour of their powers of absorption,
which enables them to incorporate a greater quantity of
the earthy matter dissolved or floating in the increased
quantity of sap they suck up.
CARoline.—But, on the other hand, they must contain
a greater quantity of liquid, which could produce a con-
trary effect.
MRs. B.-Recollect that intensity of light, increases
the power of evaporation, as well as that of absorption:
the plant, therefore, retains no superabundance of liquid,
although it acquires more of the solid particles which it
held in solution. The compactness and hardness of
plants exposed to an excess of light, offer some impedi-
ment to their growth; their vessels, deficient in elasticity
ON PLANTS. 95
and flexibility, are not so susceptible of being elongated
by the fluids which circulate within them. Mountainous
plants are therefore more diminutive in size than those of
the plain.
EMILY.—But this is far from being the consequence of
exposure to light in hot climates, where the vigour of ve.
getation greatly surpasses that of our more moderate
temperature, and where plants are in general of much
larger dimensions than with us.
MRs. B.—It is to the intensity of heat, rather than of
light, that they owe their superiority. When these two
causes act simultaneously on plants, they concur in pro-
moting the vigour of vegetation. The intensity of heat
tends to distend the vessels indurated by the deposition of
carbon, and to accelerate and give increased impetus to
the motion of the sap ; which, flowing profusely through
these firm yet still elastic vessels, produces a force of ve.
getation, and a magnitude of dimensions, unknown in
our less genial climes.
The mountain plant, on the contrary, is peculiarly ex-
posed to cold; the chilled and languid sap traverses with
difficulty the indurated vessels, the circulation of all the
juices is checked, and the vigour of vegetation propor-
tionally diminished.
CARoline.—And yet the flowers on mountainous plants
appear to me unusually large.
MRs. B.-It is an observation which has been frequent.
ly made; but I am inclined to think it is an illusion, pro-
duced by the comparative diminutiveness of the stem and
branches.
There is a third cause of the greater hardness of plants
exposed to intensity of light: by assimilating a more
considerable quantity of carbon, the plant at the same
time decomposes and incorporates a greater quantity of
water. It is not known how this operation is performed;
but the water, no longer in a liquid form, augments in-
stead of diminishing the solidity of the plant.
CARoll SE,--I should be curious to examine also the
other side of the question: that is to say, the effects of
a deficiency of light, such as occurs with plants cultivated
96 ACTION OF I.IGIIT AND HEAT
within doors, in confined situations, in the shade of
forests, &c.
Mrs. B.-In the first place, they are pale from not
having a sufficiency of carbon to develope their colour.
In consequence of this deficiency of carbon, their fibres,
being soft and feeble, are easily stretched out, and grow
to a great length; as you may possibly have seen potatoes,
when sprouting in a dark cellar, shoot out weak slender
branches, six or eight feet in length,
A deficiency of light diminishes the power of evaporn-
tion still more than that of absorption, so that the plant
retains an excess of liquid, and becomes literally dropsi-
cal. This state of saturation diminishes both their smell
and their savour. Advantage is taken of this circumstance
to soften the flavour of vegetables when too strong; that
of celery, for example, is tempered by burying the stem
in the ground, and sheltering it from the light, the leaves
alone are suffered to appear above ground. In these the
green colour is developed, while the stem remains perfect-
ly white.
CARollix.E.—But since it is the leaves which occasion
the deposition of carbon, I should think the purpose would
be more effectually accomplished by covering them up with
earth also, or by stripping them off the stem. And by
depriving the plant of its means of evaporation, you would
also increase the retention of sap, and render the plant
more tender and less strongly flavoured.
Mrs. B.-But such extreme measures would check
vegetation, and render the plant diseased, if not actually
destroy it.
It is with the view of making lettuces white and tender
that they are tied up, so that the external leaves are alone
exposed to the light.
CAROLINE.-It is not necessary for the gardener to
perform such an operation on cabbages; for Nature takes
this precaution so completely, that it is the external leaves
only which develope any colour; the heart being quite
white and tender, from a deficiency of carbon and a super-
abundance of water. Endive is also artificially whitened,
and its flavour softened, by being covered with tiles; the
ON PLANTS, 97.
green leaves of endive, which have not been thus shel.
tered from the light, are very unpleasant to the palate
from their bitterness. But vegetables thus whitened,
though tender, are generally crisp, not soft.
MRs. B.—That crispness would have been converted
into a hardness approaching to woody fibre, if the plant
had not been sheltered from the light. The crispness is
very agreeable to the palate in lettuces and endive when
eaten raw, and it becomes perfectly soft by cooking:
while those parts of a vegetable in which the woody fibre
begins to be developed, by the deposition of carbon, after
cooking remain tough and stringy. You must have no-
ticed this difference in every dish of cardoons and of
celery which is served at table: those parts from which
the light has been completely excluded are quite soft and
tender, while those ribs which have been partially expo.
sed to it are more indurated and fibrous.
It was supposed by the ancients, and, indeed, taught by
their great naturalist, Aristotle, that the verdure of plants
was developed by the atmosphere, and that it was the
exclusion of air which prevented the roots from assuming
that colour.
ExILY.—What would be the consequence of depriving
a plant entirely of light?
Mrs. B.-The leaves would become dropsical and fall
off: fresh leaves would, indeed, sprout; but these, having
no power to decompose carbonic acid, would be complete.
ly etiolated. Deprived of carbon, and in a great measure
of the earthy matter deposited by evaporation, the new
shoots would be soft and feeble, but considerably elonga-
ted by the absorption of fluid which they have not power
to throw off.
Mr. Bonnet of Geneva cultivated some peas in a cellar
totally dark, and they were completely etiolated.
ExILY.—Pray, can you tell me why plants turn their
leaves and flowers, and even stretch out their branches.
towards that side on which the light predominates?
Mrs. B.—Some have imagined that this preference
resulted from a sort of instinct; others have gone so far
as to discover in it an indication of sensibility.
98 ACTION OF LIGHT AND HEAT
EMILY.—I begin to take such an interest in plants,
since you have made me better acquainted with them,
Mrs. B., that I should be delighted to find they were raised
something above the mere passive mechanical beings, in
which Nature carries on her chemical and physical pro-
cesses without their interference.
MRs. B.-In all organised beings, life plays so consi-
derable a part, as effectually to distinguish them from
mere brute matter; but, in regard to the instinct and
sensibility of the vegetable creation, I fear we must aban-
don the subject to poets, who have often treated it with
much beauty.
The inclination of plants towards the light, we sober-
minded botanists account for in a far less romantic manner.
I must relate to you an experiment made by Mr. Texier,
which shows that plants, far from being endowed with
feeling, are mechanically compelled, by their kind parent
Nature, to turn towards that quarter which is most condu-
cive to their well-being. Mr. Texier placed a plant in a
dark cellar, where it was supplied by openings on the one
side with light, and on the other with air; and the plant
was left at liberty to give the preference to either. In a
short time the point was decided: both leaves and branches
extended themselves towards the light. This partiality
may, perhaps, be thus explained. Those parts of a plant
most exposed to the light, becoming harder and less sus-
ceptible of elongation than the parts more in the shade.
the two sides being unequal, the one is obliged to yield
to the other; the soft, yielding, elongated side to that
which is harder and more contracted. If one side of a
branch is more elongated, it will take a curved form, as
may be seen in the figure (Plate IV. fig. 5,) whère the
dark line represents the accumulation of carbon and
contraction of growth, and the fine line, the sofier texture
and greater elongation; and thus you see that the plant
mechanically assumes a position in which it may receive
the greatest benefit from an element so essential to its
welfare.
CARolase.—This is extremely curious; and it accounts
for the tendency of plants towards the light, in a manner
ON PLANTS. 99
So simple and clear, that, mechanical as it is, I cannot
doubt its correctness.
Mrs. B.-It has been suggested, that advantage might
be taken of this natural mode of curving wood for the
construction of ships, the ribs of which are bent by artifi-
cial means.
Let us now proceed to examine the effect of temperature
on plants.
Heat excites and accelerates the circulation of the
juices of plants, as it does those of the animal frame; but
this effect varies in different species of plants, and even
in different individuals of the same kind. It is the acce-
lerated motion of the sap, during the warmth of spring,
which determines the period of the budding of the plant;
and, as the temperature of the season increases, pro-
duces a greater absorption by the roots, of evaporation
by the leaves, developes the blossom, and, finally, ripens
the fruit.
The action of heat in these operations is not merely
mechanical, but produces effects on the living plant very
analogous to those which it does on animals.
When, on the contrary, the temperature of the soil is
as low as the freezing point, the spongioles finding no
fluid to imbibe, the plant, deprived of sustenance, lan.
guishes; and, should this privation continue any length
of time, it perishes of famine.
EMILY.—And if the heat be so intense as to evaporate
all the water of the soil, the plant will be equally de-
prived of nourishment.
MRs. B.-The effect is similar, though produced by so
opposite a cause. The plant will in the last case, how-
ever, perish sooner; for, besides being deprived of sus-
tenance, it will evaporate its own moisture. But let us
first inquire into the effects of a low temperature on
plants. Water may freeze within the plant, but it is less
liable to congelation after, than before being absorbed by
the roots; not only because it is better sheltered from the
external cold, but because the motion of the sap is unfa-
vourable to congelation.
If the stem of a tree freezes, the elasticity of the ves.
100 ACTION OF LIGHT AND HEAT
sels requisite for the circulation of the juices is destroyed,
and the plant perishes both from cold and hunger. But
if merely the leaves and buds be frozen, they alone are
destroyed; and the sap, which the stem continues to
transmit to the branches, enables them to sprout out new
buds and fresh leaves.
• CARolin E.-So, a man would still live, were his nose
or fingers frozen. The analogy, however, will go no fur-
ther, for he has not the advantage of sprouting out new
4)In eS,
And, on the other hand, what degree of heat will plants
support 7
MRs. B.-It varies extremely, depending on a variety
of circumstances. The Viter agnus castus has been
known to strike root in water at the temperature of 170
fahrenheit.
When one of the hot-houses of the Botanical Garden
of Paris was burnt, all the plants within it perished ex-
cepting the flax of New Zealand, which resisted the tem-
perature of a general conflagration that consumed even
its leaves.
The temperature of some few plants experiences an
elevation at the moment of flowering : that of the Arum
muculatum rises from fourteen to twenty-one degrees,
when its blossom expands between three and five o'clock.
EMILY.--Do plants, like unorganised bodies, partake
of the temperature of the atmosphere in which they
grow 1 I should have imagined that they must be
warmer; for, since some portion of the water which a
plant absorbs remains incorporated in it under a solid
form, in changing its state from fluid to solid, it must give
out its latent heat, which would raise the temperature of
the plant.
CARoline.—But you forget, Emily, that two-thirds of
the water which the plant absorbs is evaporated, and, by
changing its form from liquid to vapour, cold must be
produced. Now, as the quantity which assumes the
form of vapour is much greater than that which becomes
solidified, the temperature of the plant should ultimately
be lowered beneath that of the atmosphere in which it
lives.
ON PLANTS. 101
Mrs. B.-Each of your opinions have been sanctioned
by different naturalists; but, however exact these calcu-
lations may be in the laboratory, they can give us but
very little insight into the chemistry of vegetation, where
that mysterious principle life performs so essential a part.
EMILY.—Yet, is it not easy to ascertain by the thermo-
meter whether plants differ in temperature from the atmo-
sphere 7
MRs. B.-It appears by that test, that the trunk of a
tree is colder in summer, and warmer in winter, than the
air by which it is surrounded; and the larger the stem,
the more this difference is manifest. But the reason of
this is very simple: the roots draw their nourishment
from a depth of soil, well sheltered from both extremes
of heat and of cold : the water they absorb remains
throughout the year of a moderate temperature; and the
stem, which serves as a channel to transmit this water to
the branches, naturally acquires the temperature of the
fluid it conveys. The sap thus tends to cool and refresh
the plant during the heat of summer, and to cherish and
preserve it from being injured by the severity of winter;
but should this severity be so intense or of such long du-
ration as to penetrate into the deep recesses of the soil,
whence the sap is drawn, the temperature of the tree
will gradually descend to that of the atmosphere.
CARolin E—The stem has still another defence from
the cold, in the several layers of bark; which we may,
I suppose, consider as so many warm coats to preserve
the internal temperature of the tree ?
MRs. B.-Certainly. The bark is a bad conductor of
heat, and, like flannel clothing, serves equally to keep in
warmth during winter, and to exclude heat in the summer.
Notwithstanding all these precautions, which Nature
has so wisely taken to preserve the equable temperature
of plants, the water within the stem is sometimes frozen ;
and, as water when converted into ice occupies a larger
space than in its fluid state, it bursts the vessels in which
it is contained, and injures, if it does not destroy, the
texture of the plant.
ExILY-But should this occur after a dry season, so
9*
102 ACTION OF LIGHT AND HEAT
that the cells which contain the water be not filled, there
will be room for its expansion in freezing.
MRs. B.-True; freezing may then take place without
considerable injury to the plant: it is only when the parts
become disorganized, from the fracture of the vessels of
the cellular system, that the plant itself is said to be
frozen. The more water, therefore, plants contain, the
more liable they are to injury from frost; and, accord-
ingly, we find that aqueous plants are those, most easily
frozen. What parts of a plant should you suppose most
liable to be attacked by the frost?
CARoline.—Those which contain most water: the
leaves, where that liquid is conveyed to be evaporated;
and the buds, where, during spring, the sap is brought in
such abundance for their nourishment. Besides, the
leaves and the buds are most exposed to the air, while
the stem and branches are well defended from its incle-
mency by their warm clothing, the bark.
Mrs. B.—You have judged rightly. If the frost be so
inveterate as to attack the stem, it is the alburnum, as
being the most moist and tender, which first suffers; af.
terwards the liber, the internal coating of bark. If this
freezes, death must ensue, as the vessels which convey
the cambium are lodged in this coating. The external
layer of bark is the driest of any part of the plant, being
constantly subjected to the inclemencies of the season.
It is often injured, and in the lapse of time destroyed, and
peels off; but it is never frozen.
ExIILY.—Plants must be more liable to freeze in the
spring than in the autumn, at an equal temperature, be-
cause they contain more water in the former than in the
latter season.
Mrs. B.-True. In autumn the absorption of sap
diminishes, in the spring it increases, both in quantity
and celerity of motion, in order to provide for the budding
of the plant; and if in this season a frost should prevail,
there is great danger of the plant falling a sacrifice to it.
Plants of different species vary much in their power of
resisting cold. Oaks do not freeze at 56° below the
freezing point of Fahrenheit; beech will support 79°, an
ON PLANTS, 103
intensity of cold which congeals mercury. Mr. De
Candolle found snow drops in blossom on Mount Saleve
beneath the ice; and Captain Parry, in his Polar expedi-
tions, discovered many plants, in full leaf and ready to
blossom, encased in ice.
It is remarkable that plants, which are the greatest
sufferers by extreme cold, are at the same time most
liable to injury from intense heat. But this apparent in-
consistency admits of an easy solution. We have ob.
served that aqueous plants are easily frozen; they also
evaporate abundantly ; therefore, when exposed to ex-
treme temperature, whether of heat or cold, they will be
either frozen or dried up.
Plants which secrete a viscous juice do not easily
freeze: the tenacity of this thick, sticky fluid prevents,
or at least impedes, that arrangement among the parti-
cles which is necessary to produce congelation. Free-
zing, you know, is a species of crystallisation; and it is
requisite that each particle of liquid should be free to
range itself in that order which is essential to the forma-
tion of such regular bodies as crystals.
CAROLINE.-the rising sap then must freeze more
easily than the descending sap or cambium, as the latter
is thicker and more viscous.
Mrs. B.—Yes; and there is also another reason why
the sap is more liable to freeze than the cambium : the
former moves with greater celerity, so that its particles
more easily place themselves in the order of crystallisa-
tion.
ExIILY.—Might not recourse be had to the expedient
of stripping the plant of its leaves, in order to diminish
the velocity of the rising sap, when in danger of free-
zing? For by depriving a plant of the organs of evapo-
ration you lessen its power of absorption.
CARolin E.-But, by preventing the elaboration of the
sap in the leaves, you hinder it from acquiring that con-
sistence which enables it to resist congelation; you ren-
der the plant dropsical by the accumulation of water:
and aqueous plants, Mrs. B. has told us, are most liable
to freeze.
104 ACTION OF LIGHT AND HEAT, ETC.
MRs. B.-Emily’s expedient has been tried, but not
without danger of the consequences you deduce from it.
Fleshy fruits, such as oranges, apples, and pears, re-
quiring a great quantity of sap to supply sustenance, oc-
casion a great absorption by the roots. These plants
are, consequently, particularly liable to injury from frost;
and, when thus endangered, it is a useful precaution to
gather the fruit, in order to secure the tree. In the
south of France, the oranges are gathered on the first
appearance of a frost; and should this operation not b
completed before the frost sets in, it frequently occurs
that the side of the tree on which the fruit remains is at-
tacked by the frost, while that on which it has been
gathered escapes uninjured.
CARoLINE.—Then, in cases of such urgency, they
should begin by gathering the fruit on the north side of
the tree, as being most exposed to the cold.
EMILY.—Some fruits, like the peach, are coated with
a soft down ; which, I suppose, answers the purpose of
warm clothing
MRs. B.-Yes; it is perhaps, even a better preserva.
tive from the cold than the coatings of the epidermis.
This soft down encloses and confines the particles of air
on the surface of the fruit on which it grows. Air, you
may recollect, is a very bad conductor of heat, and espe-
cially air in a tranquil state; that which is imprisoned by
the down affords, therefore, the most useful shelter to the
plant.
ExIILY.—I have often experienced the advantage of a
precaution of this nature, by holding up my fur-tippet
before my mouth when encountering a sharp frosty wind;
the air, held captive by these slender threads, reposes
tranquilly in its downy prison, and becomes mild and
genial to breathe.
MRs. B.-You must observe, also, that, during its cap-
tivity, it is tempered by the warmth of the breath you
expire, before being inhaled by the lungs; so that, in
fact, you breath a tepid, instead of a frosty air.
A layer of air is also retained captive between the
epidermis and the bark, which is, perhaps, a still better
ON THE NATURALISATION OF PlaNTS. 105
preservative to the plant than the bark itself: it is a deli-
cate under-garment, which the stem wears beneath its
more cumbrous clothing of epidermis.
CARolin E.-The epidermis was itself, I thought, a deli-
cate covering to the internal layers of bark.
MRs. B.-That depends upon the nature of the plant,
and the part to which it belongs. The epidermis of the
leaves and buds is delicate, but that of the stem and
branches of a venerable oak is of a very different de-
scription ; the bark in general which covers the trunk
consists almost wholly of carbon; which, being a very
bad conductor of heat, answers the double purpose of
confining the internal heat in winter, and excluding the
external heat of summer.
The epidermis itself is sometimes single, sometimes
double or triple, but more commonly consists of a num-
ber of layers. So many as one hundred and fifty have
been counted in the epidermis of a tropical plant; and
so great a number still remained that the calculation was
abandoned from the difficulty of completing it.
At our next interview we shall examine, how far plants
will admit of being naturalised to a climate differing in
temperature from that in which they are indigenous;
and what are the precautions necessary to be taken in
transplanting them to a foreign country.
CONVERSATION VIII.
ON THE NATURALISATION OF PLANTS.
Mrs. B.-In estimating the effect of diversity of cli.
inate on plants, the point most important to be considered
is the difference of temperature. The nature of the soil,
the air, water, and light, are circumstances comparative-
}. trifling, compared with the abundance or deficiency of
eat,
EMILY.—I should have imagined that the quality of
the soil and the quantity of water would have been of
still greater consequence than the temperature.
106 ON THE NATURALISATION OF PLANT'S.
MRs. B.--When we wish to naturalise a foreign plant,
art may do much in rendering the soil analogous to that
in which it originally grew, in affording it a due quantity
of water, in sheltering it from, or exposing it to the light.
The nature of the air varies very little in any latitude,
but its temperature most remarkably; and over this art
has little or no control.
CARolisE.—You forget our hot-houses, Mrs. B., where
we produce whatever temperature we choose.
MRs. B.-True; but the plant cultivated, or I should
rather say forced, in such an artificial atmosphere remains
a foreigner, and does not become a naturalized subject of
the vegetable realm.
`If you compare the mean temperatures of different
countries, you will be surprised to find how much more
nearly they approximate to equality than you would at
first imagine. For instance, those of England and of
Switzerland do not vary above two or three degrees; yet
they frequently will not admit of the cultivation of the
same plants. In Switzerland it is hotter in summer than
in England, owing to the latitude; while its local eleva-
tion, and the vicinity of mountains covered with snow,
render it colder in winter. The more equable tempera-
ture of England, throughout the year, enables every
species of laurel, and even Rhododendrons, to support
the winter with impunity. In Switzerland, the common
laurel, if it escape being frozen, suffers so much as greatly
to injure its vigour and its beauty : the contrast of a
strong vegetation in summer, suddenly checked by the
severity of winter, ill accords with its nature. The lau.
rustinus and the Portugal laurel are unknown in Switzer-
land, except as green-house plants; while, on the other
hand, the fruit of the vine, which we can but imperfectly
ripen in England, in Switzerland affords a luxuriant
vintage.
EMILY.—I am often inclined to envy them their olean-
ders and pomegranates, which blossom so beautifully in
the open air, and require the shelter of a green-house only
in winter; while we produce very inferior plants of the
same description even in our hot-houses.
ON THE NATURALISATION OF PLANTS. 107
CARo11NE.—Yet the temperature of Switzerland must
be lower than its latitude would indicate, owing to its
elevated situation; for being nearly in the centre of
Europe, whence almost all the great rivers have their
source and flow into the sea, it must be the spot most
raised above that level.
MRs. B.-Certainly. In estimating the temperature
of a climate, the prevalence of hot or cold winds, such as
the sirocco in the south of Italy, the mistral in the south
of France, and the bise in the valleys of Switzerland,
should be taken into consideration, as well as the locality
of the spot; which, independently of its degree of elevation
above the level of the sea, is liable to be aiſected by a
variety of circumstances. One of these, which, however
remarkable, naturalists have not hitherto been able satis-
factorily to account for, is, that in countries of similar
elevation and latitude, the temperature is always higher
in those situated on the western than on the eastern side of
a continent. It is warmer, for instance, at Nantes, on the
western shore of France, than at Quebec, on the eastern
shore of America, both being very nearly of the same
latitude. At Quebec, snow-shoes and sledges are in
general use during several months of winter, and booths
are built upon the frozen river St. Lawrence; while at
Nantes frost and snow are little known, and of short
duration.
EMILY.— But how far can plants accustom them-
selves to a climate and temperature which is not natural
to them
Mrs. B.-It varies extremely, according to the nature
of the plant. The horse-chesnut, which is so well natu.
ralized to our northern climates, that it braves even the
inclement skies of Sweden, was originally brought from
India; where it grew, it is true, on mountains, but of no
very considerable elevation. Some plants succeed only
partially on being transplanted to a foreign climate. Thus
the artificial grasses, such as clover and cinquefoil, thrive
very well as grasses: they are cut down when in blossom,
the heat of summer being seldom sufficient to ripen their
seed, we are under the necessity of importing it from
warmer climates, in order to renew them.
108 6N TIIE NATURALISATION OF PLANTS,
EMILY.—I thought that the artificial grasses were cut
down at that earlier period of their growth, as being then
most tender, and best suited for the nourishment of cattle.
Mrs. B.—That is true: but were we able to ripen the
seed, we should cultivate a portion for that purpose, in-
stead of annually renewing it from foreign parts.
CARoll NE.-Why have these grasses obtained the
name of artificial
Mrs. B.-Because they require continued cultivation
from the seed. They are not perennial, but must be
constantly resown; while most of the grasses of our pas-
tures and meadows spread by the root.
There are many plants which will not admit of trans-
planting to a colder climate : thus the orange and the
olive have made no progress northward since the time of
the Romans, but are still confined to the same limits.
CARolrx.E.—The orange-tree bears our climate under
shelter of a green-house extremely well.
MRs. B.-There are few plants which cannot be culti-
wated with some degree of success, by the artificial tempe-
rature of a green-house or a hot-house; but I am speaking
of their being naturalised to a climate, so as to admit of
being raised in the open air.
When you make the experiment of introducing a new
plant from a warmer climate, you must treat it with great
care, and endeavour, by gentle gradations, to wean it
from its native country, and accustom it to our more
inclement skies. You should begin by placing it in a hot-
house; the following year you may try the green-house;
and, if it does not appear to suffer from this change, you
may finally expose it to the open air. While the plant
undergoes this species of education, you have the advan-
tage of studying its habits, the nature of the soil most
favourable to its growth, the quantity of water it requires,
the degree of light to which it should be exposed, the
wind which it will support, and a number of minute cir-
cumstances which will indicate the situation and treatment
most congenial to it, on transplanting it into the open air.
This knowledge of the habits of plants is highly essential
to their success, in becoming naturalised to a foreign
climate.
ON THE NATURALISAT.10N OF PLANTS. 109
ExILY.—Undoubtedly. If it be found that they require
unuch moisture, it will be expedient to plant them in hol-
lows, rather than on rising ground. When the plant is
tender and delicate, so that light, heat, and shelter, be-
come essential to its preservation, you must select a
southern aspect, that it may derive every possible advan-
tage from the sun, and be sheltered from the north wind.
MRs. B.-You must also pay attention to plant it rather
deep in the soil, in order that its roots may be supplied
with water of a moderate temperature, and that the neck
or vital part of the plant be sheltered from the inclemency
of the weather, by being well covered with earth. Then
it should be transplanted in the spring, in order that it may
be gradually accustomed to a diminution of temperature,
instead of being suddenly exposed to the severity of win-
ter. Besides, if planted in the spring, it will be hardened
against the following winter by the deposition of carbon
during the summer. It is desirable also to plant it in a
rich vegetable soil, in order to afford it plenty of nourish-
Inent.
CARo11NE.-In Switzerland, they plant rhododendrons
and kalmias in pots of remarkably black earth.
MRs. B.-The bog-earth or peat-earth of England,
though less rich, is of the same nature, consisting chiefly
of vegetable remains. There are whole districts in Bel.
gium of this nutritive vegetable soil, which is converted
into nursery gardens for raising kalmias, rhododendrons,
and other plants of this description, where they grow
and prosper in the open air. In England, the rhododen-
dron succeeds perfectly well in our gardens, though the
soil is less rich in carbon than the bog-earth of Belgium;
but the moisture of our climate is particularly favourable
to that, as well as to every species of laurel, and to ever-
green plants in general.
In transplanting from a colder climate, very few pre-
cautions are required: an elevated situation is desirable,
and a sufficiency of water to provide for the more abun-
dant evaporation to which the plant is subjected.
Plants brought from a warmer climate should be water.
ed but moderately, because the power of evaporation is
10
110 ON THE NATURALISATION OF PLANTS,
checked by the diminution of temperature. This is par-
ticularly to be observed in autumn, when the cold weather
first sets in.
ExtILY.—And in that season, the direction, I should
suppose, would be applicable to plants of every descrip-
tion, none of them being capable of evaporating so much
during winter as summer, especially when deprived of
their organs of evaporation—the leaves.
MRs. B.-True ; but not equally applicable to those
which preserve them. Such green-house plants, for in-
stance, as geraniums and orange-trees, which retain their
organs of evaporation throughout the winter, though that
function is more imperfectly performed during this season,
will admit of being watered with less parsimony than
others.
ExIILY.—Do you approve of sheltering delicate plants,
by covering them with straw or inatting during the winter 7
MRs. B.—If the spot in which they grow be elevated,
and the soil dry, it may be done with advantage; but in
low damp situations, such a precaution might occasion the
plant to rot, particularly evergreens, as the covering
would prevent the evaporation of any superabundant
moisture by the leaves. In such cases, it is better to
leave the plant exposed, taking care, only, to shake off the
snow which, if melted by the sun during the day, runs
down the stem and branches, and insinuates itself into
any little crevice it may chance to find in its passage, or
is absorbed by the buds and tender parts of the plant as it
trickles over them. Then at night, if this water freezes,
it injures, if it does not destroy, the texture of the parts
in which it is lodged.
CARoline.—It must surely be desirable to plant such
trees against a wall in a southern aspect, even under the
inconveniences to which such a state of confinement
subjects them.
MRs. B.—It is attended with several advantages, which,
in the initiation of tropical plants to our climate, often
more than compensate the injury resulting from confine-
ment. A southern wall not only affords shelter from the
north wind, but becomes a source of heat, by the trans-
mission of the sun's rays to the plant.
ON THE NATURALISATION OF PLANTS. 111
EMILY.—The white walls of France and Switzerland
must reflect a great deal of heat; but I should not have
supposed that our brown brick English walls would have
produced much effect, for they must absorb more heat
than they reflect.
Mrs. B.-The rays, whether reflected or absorbed by
the wall, are alike beneficial to the tree planted against
it; for no sooner does the temperature of the wall be-
come elevated by the absorption of heat than it radiates
this heat, which is thus transmitted to the tree in contact
with it.
The injurious effects of the captivity of the branches
must, however, be taken into consideration; for, besides
the salubrious exercise which the free access of air af.
fords to a plant, this agitation augments the power of
evaporation—a power which it is very desirable to en-
courage, as it is necessarily diminished in a climate of
a lower temperature than that in which the plant was
placed by Nature; especially in England, where the at-
mosphere is impregnated with moisture. It is owing to
this circumscribed power of evaporation that wall-trees
are less hard in their texture, and contain less carbon,
than those which grow freely.
ExIILY.—Let me endeavour to recapitulate the several
circumstances to be attended to in transplanting from a
warm to a cold climate. In the first place, you must
make the plant pass through the various gradations of the
hot-house and green-house, previous to exposing it to the
open air; you must then plant it in the spring, deep in a
richly-carbonised soil, and cover up the vital point of
junction between the stem and the roots. It must be
placed in a southern aspect, or against a south wall, wa-
tered with great moderation: the fruit must be gathered
before the frost sets in ; and the plant may be covered
with matting in winter, if situated on an elevated spot in
a dry soil.
MRs. B.-I believe you have enumerated all the di-
rections I have to give you on this point.
I shall add a few remarks on green-houses and hot-
houses, as necessary to the cultivation of such plants as can-
112 ON THE NATURALISATION OF PLANTS.
not be familiarised to our climate. They should both be
situated, as far as is practicable, in a southern aspect.
EMILY.—But when this is not attainable, to which do
you give the preference, a south-east or south-west
aspect.
Mrs. B.-The first has the advantage of affording re-
lief earliest to a plant which has suffered from the cold
during the night; the latter that of sheltering it from the
severe east wind : upon the whole I should be inclined to
choose the latter.
Vertical windows have the advantage of not retaining
the snow, the disadvantage of admitting less light and
heat; and in England, where we are not much troubled
with snow, and require all the heat we can obtain in win-
ter, the inclined windows are certainly preferable, and are
almost universally adopted; while on the Continent, where
less heat is required, vertical windows are more common.
In southern climates, the house must not be built deep,
in order to admit the sun’s rays to every part ; in northern
climes, the sun's rays falling more obliquely, a greater
depth of building is admissible: the roof should project
and be coved, so as to collect the rays of the sun and re-
flect them into the house.
In order to protect hot-houses and green-houses from
humidity, they must be warmed and aired at the same
time : the heat both dissolves the moisture and prevents
the plants from suffering from the external air while the
windows are open ; and the current of air carries off any
moisture which is not dissolved.
The finest hot-houses are in Russia, where the wealth of
the higher classes enables them to indulge in luxuries.
In their cold climate, hot-houses and green-houses are con-
sidered as necessary articles of comfort. In England,
Mr. Loddiges' establishment at Hackney exhibits the
most perfect model of hot and green-houses : they are
warmed by vapour, and when necessary, watered by the
tepid water into which the steam is condensed. The
building is one thousand four hundred feet in length, and
divided into compartments, each of a different tempera-
ture.
AcTION OF THE ATMOSPHERE, ECT. 113
EMILY.—What effect has the tan which is used in
hot-houses 7
MRs. B.-It produces heat, by undergoing a degree of
fermentation; but it also generates humidity, and heat
and humidity favour the propagation of fungi and of
worms; and should the roots of the plant grow below
the pot, and penetrate into the tan, its contact is inju-
TIOUIS,
The smaller and lower the house, the more favourable
it is to young and delicate plants: the heat always rises,
so that in large and elevated houses the small plants of
the lower range are situated in an atmosphere of cold
air. It is for this reason that slips of green-house plants
are generally placed in beds covered with glass, in order
to strike root, where they receive as much heat in as
small a space as possible.
CONVERSATION IX.
ON THE ACTION OF THE ATMOSPHERE ON WE-
GETABLES.
MRs. B.-This morning we shall turn our attention to
the manner in which the atmosphere affects the vegeta-
ble world. It acts on plants in two ways: both mecha-
nically and chemically.
CARoline.—But in a very different manner from what
it does on animals: we only breathe the air; plants may
in some measure be said to feed on it, since they absorb
carbon from the atmosphere.
ExIILY.-They also absorb oxygen from that source;
but it is true they restore it with ample interest, thus pu-
rifying the air we animals have contaminated by our
breath. But since carbon is such a favourite food of
plants, I should like to try the experiment of enclosing a
weakly, debilitated plant in an atmosphere of carbonic
acid, to see whether the abundance of such nourishment
would not restore its vigour.
10*
114 ACTION OF THE ATMOSPIHERE
MRs. B.-The quality of the food would be excellent;
but nothing is good when administered in excess. Such
an experiment would resemble the attempt made to re-
store pulmonary patients to health by giving them pure
oxygen gas to respire: at first it seemed to be attended
with beneficial effects; but the deleterious consequences
occasioned by too great excitement of the lungs, was
soon discovered, and the experiment abandoned. We
cannot be too cautious in our proceedings when we ven-
ture to deviate from the paths which Nature has pointed
Out.
The chemical action of the atmosphere on plants we
have already so fully investigated in our preceding Con-
versations, that, although it be no less applicable to our
present subject, it would be but repetition to return to it.
I have not, however, yet mentioned, that the electricity of
the atmosphere appears to affect plants; it is at least an
undoubted fact, that vegetation is accelerated during a
Storm.
EMILY.—May not that arise from the agitation pro-
duced by the wind? Branches being tossed to and fro, must
greatly increase the velocity of the sap, and the deposí.
tion of its nutritive particles; the evaporation from the
leaves must also be considerably augmented by the wind
blowing them about, and carrying off the vapour the in-
stant it is formed. Such a state of stimulus might be fol-
lowed by a debilitating re-action, as is the case with us,
after excessive exercise ; but, while it lasts, it must pro-
duce a very great increase of action throughout the frame.
MRs. B.-That may possibly be a concurring cause of
the phenomenon, but is not sufficient to account wholly
for it. Mr. De Candolle mentions the remarkable growth
of the branch of a vine during a storm, of no less than
an inch and a quarter in the course of an hour and a half;
now the tree grew against a wall, so as to be little acces.
sible to the wind.
The quantity of water contained in the atmosphere is a
point of great importance to plants. Water, you may re-
collect, exists in the atmosphere in two different states :
in the one it is so completely dissolved, that the air feels
ON VEGETABLES. 115
perfectly dry to us, and affords no moisture to the vegeta-
ble part of the creation. It is heat which enables the air
to perform this solution; therefore the higher its tempera-
ture, the more water it can dissolve.
CARoline.—Then the atmosphere in the torrid zone,
though driest, contains most water:—that appears very
paradoxical.
MRs. B.—It is nevertheless true. Whenever the ai
cools, its power of retaining water in solution diminishes.
CARoline.—This must happen, then, not only when the
weather changes from hot to cold, but every evening
after sunset.
Mrs. B.-Accordingly, we continually see misty va-
pours floating in the atmosphere in the evening, and the
ground more or less covered with dew : all this is water
precipitated by the diminution of temperature of the air.
In the morning, when the sun has sufficiently warmed the
atmosphere to enable it to dissolve these fogs and vapours,
they disappear.
The other state in which water exists in the atmosphere
is that of a fine subtle vapour, diminishing its clearness,
and giving us the sensation of humidity.
EMILY.—The latter state, I should suppose, would be
the most advantageous to vegetation, for plants almost
always require water.
MRs. B.-It is to the dampness of our climate that we
owe the fine grass of our beautiful meadows and lawns,
for which England is so celebrated, and which are in vain
attempted to be imitated on the continent; unless it be in
some very elevated spots, where the grass is nurtured by
the mountain mists/ It is to this cause, also, that we are
indebted for the prosperity of our laurels, and a variety
of evergreens; yet a damp climate has its attendant dis-
advantages, even as regards the vegetable creation. Fogs
and vapour diminish the quantity of light, and, conse-
quently, the numerous benefits resulting from it, such as
absorption, evaporation, deposition of carbon, and deve-
lopement of colour. In this point of view, therefore, a
very moist climate injures the beauty and vigour of vege-
tation.
116 ACTION OF THE ATMOSPIIERE
Trees growing on mountains where they are much ex-
posed to vapour, are very liable to suffer from what is
commonly called a white frost. The clouds and mists, so
prevalent in those elevated regions, bedev their branches
with a light coating of watery vapour, which easily freezes
during the night; the morning mist attaches itself to this
thin layer of ice, and shoots into minute frosty crystals,
called a white frost.
CAROLINE.—The white frost which we so commonly
see on the grass, is formed I suppose, by the freezing of
the dew.
MRs. B.-Yes; and it is, you know, so slight as to dis-
appear soon after the sun has risen above the horizon.
Moisture is particularly inimical to blossoms: if it comes
in contact with the anthers, it destroys them, and the flower
bears no seed. This disease often affects the vine, and
not unfrequently corn, to the great injury of the vintage
and the corn-harvest. Moisture is prejudicial, also, by
giving rise to the propagation of fungi, of purasitical
plants, and even of worms.
There are some plants to which the moisture of sea-
breezes is so essential, that they cannot be cultivated in
any other situation than on the shores of the ocean.
EMILY.—These plants, doubtless, require sea-salt; and
yet the vapour which exhales from the sea is perfectly
sweet, the clouds which they form are never impregnated
with salt ; how, therefore, can plants obtain it !
Mrs. B.-Not from the vapour which rises from the
sea, but from minute drops of salt-water, which are pro-
jected into the air by the agitation of the waves, and car.
ried by the wind to the shores. Salsola kali, or kelpwort,
is a plant of this description: if grown in an inland situ-
ation it contains not a particle of soda, the alkali from
which it derives its value; for this can be obtained only
from muriate of soda, or sea-salt. During the late war
between France and Spain, the French, being greatly dis-
tressed for soda, which they had imported chiefly from
Spain, attempted to cultivate kelpwort on the lills border-
ing the sea-shore in the south of France. When planted
on the southern side of the hill, sloping towards the sea,
ON VEGETABLES, 117
the crop succeeded perfectly; and, the price of soda
having risen very high, one single harvest repaid the price
of the land on which it was raised. But when planted
on the north side, where it was not exposed to the briny
particles, it failed completely, and the plant contained no
other alkali than potash.
EMILY.—This explanation solves a difficulty which had
often perplexed me. The sea air is, you know, much re-
commended to invalids as a tonic; and the fogs and damp
mists, so prevalent on the sea-shore, do not appear to be
attended with the debilitating effects produced by inland
fogs: this must be doubtless owing to the tonic qualities
...he briny particles with which the sea-air is impregna-
ted.
CARoll NE.-It is true, one can seldom walk out on the
sea-shore without one's dress suffering from humidity;
and the salt with which this humidity is loaded is often so
strong as to be sensible to the taste. But this prevails
only within some few hundred yards of the shore: on ri-
sing upon the downs it is no longer perceptible; and yet
it is the air of these downs which is reckoned so particu-
larly invigorating.
MRs. B.-The saline particles are too ponderous to be
carried to such a height; but there you experience the
salubrious effect of mountain-air. The salt not requisite
to render it tonic : it is only when you descend on the op-
posite side into the inland country, that you perceive the
want of those invigorating qualities for which the sea-air
is so celebrated.
It is remarkable that kelpwort exudes a portion of the
alkali which it receives from the atmosphere into the
.." the soil on which it has been cultivated being
ound to contain more than when such a crop has not
been raised upon it. This is owing, probably, to the
quantity it absorbs, being more than the plant requires.
EMILY.—This, then, affords an exception to the gene-
ral nature of the exudation of plants by the roots, as it
must constitute appropriate nourishment for other plants
of the same species,
118 ACTION OF THE ATMOSPIHERE
CARoLINE.-And is not the air also useful as a vehicle
to transport small seeds from one country to another?
MRs. B.—Yes; there is scarcely any resemblance be-
tween the plants of Europe and of America, excepting in
Cryptogamous plants, because the seeds of lichens, of
mosses, and of fungi, of which this family is composed.
are so small that they float in the air, and are transported
by the wind from one continent to the other.
The wind also performs the part of a careful sower.
dispersing the seeds which fall from the plant with regu-
larity over the soil.
CARo1.1NE.—I wish it would distinguish between weeds
and flowers, and confine itself to the dispersion of useful
seeds; but it seems to delight in the propagation of
weeds; if any thistles or groundsel are to be found in a
garden, the wind is sure to carry the seeds all over it.
MRs. B.-The distinction between weed and flower is
not so easily made as you may imagine. In botany we
know not what weeds are ; every plant has its use for
some purpose or other.
We have already noticed the beneficial effects of the
motion which the wind communicates to trees. That of
the palm-trees in Egypt is so powerful, when agitated by
a high wind, that the French, when in that country,
made use of them as levers to draw up water from the
Nile. The motion of the stems raised the piston of the
pumps, which fell again by their own weight.
Of the temperature of the atmosphere, which is the
point of greatest importance in vegetation, we have al-
ready fully treated. I have only to add, that plants
which grow in the plain, in countries of high latitudes,
if transported to a warmer climate, must be cultivated
in elevated situations. In Chili, for instance, potatoes
grow at an elevation of nine thousand feet higher than
they will grow in these climates.
EMILY.—The degree of latitude is, then, the inverse
of the degree of elevation from the level of the sea 7
Mrs. B.-The one serves as a compensation for the
other. It is not, however, every species of plant which
can take advantage of this sort of compensation; but the
ON VEGETABLES. 119
greater number of plants will grow equally well at a
high latitude in the plain, or in a low one on a mountain.
In an estimate made of the greatest height at which
several different species of trees will grow in the south
of France, it appears that
The Larch grows at an elevation of 7200 feet.
The Birch ................................ 6000 feet.
The Beech .................. ſº tº ſº tº º º º .... 4000 feet.
The Cherry .................. ............ 3000 feet.
The Walnut .............................. 2400 feet.
Among the Cerealia,
Rye ......................................... 6000 feet.
Wheat .............----------------------- . 5400 feet.
Turkey Corn ...--------------------------- 3000 feet.
The Vine 1800, or even so high as 2400 feet,
if the situation be particularly favourable.
Extily.—I recollect woods of birch trees, on the moun-
tains of Scotland, where they had to struggle against the
difficulties both of elevation, of latitude, and of situation;
but, it is true, they were ragged and dwarfish, and wore
the appearance of great distress.
MRs. B.-And yet their elevation was far below 6000
feet; for Bennevis, the highest mountain in Scotland, does
not rise more than 4370 feet above the level of the sea.
The larch, which is much more hardy, has been planted
upon the mountains of Scotland with great success, and
clothes their once barren sides with a delicate foliage.
The olive-tree will not grow in a higher latitude than
the southern provinces of France; and there it is only
under the most favourable circumstances of soil and as-
pect that it can be cultivated, at the height of 1200 feet.
CARoll NE.—We have seen it in Italy growing almost
to the summits of the mountains. I own that I was dis-
appointed with the Italian olive. We associate so many
pleasing and poetic ideas with the olive-branch, that I ex-
pected to partake of the beauty of its rival in the gardens
of Parnassus—the laurel; but, so far from vying with it
in beauty, the colour of the olive is so dingy, that it looks
like a willow covered with dust.
120 on THE ACTION OF water ON PLANTs.
& O
Mrs. B.-I cannot see what reason there is to expect
much similitude of appearance between the emblems of
glory and of peace. The branching of the young olive is,
however, remarkably elegant, and the lightness of the fo-
liage atones for the want of vivacity in its colour; and,
when mixed with plants of a more lively green, affords a
very agreeable variety. The olive-groves of Tivoli gave
me the impression of the most antiquated trees I have ever
beheld: their venerable trunks are torn, riven, and twisted
into a thousand fantastic forms; a profusion of youn
branches, decked with light foliage, shoot from these .
stems, and, waving their silvery tints in the sun, seem to
smile and say, We are your contemporaries; but the an-
tiquated parent whence we spring, once put forth branches
under the shade of which Cicero and Mecaenas reposed.
CARolix E.—They are the only olive-trees I ever admi-
red. Independently of their magnitude, they are interest-
ing from their appearance of age and decrepitude. The
stems, so curiously split asunder, look as if they bid defi-
ance to the violence they have suffered; and, twisting the
dismembered remnants of their stems together, seem to
verify AEsop's fable of the bundle of sticks, and acquire
additional vigour to withstand the attacks of time and of
the elements.
CONVERSATION X.
ON THE ACTION OF WATER ON PLANTS.
MRs. B.—Water may be considered as acting on plants
in several different ways: the first and most important of
which is, its being the vehicle of their nourishment. The
greater the quantity of nutritive particles which water
contains the more favourable it is to vegetation, unless it
should be so far saturated as,to be too dense to pass through
the pores of the spongioles. In that case the plant is re-
duced to the state of Tantalus, and perishes of famine in
the midst of plenty.
We have already observed, that, of three particles of

ON THE ACTION of WATER on PLANTs. 121
water which enter a plant, one only remains within it;
and this either retains its natural liquid state, analogous to
the water of crystallisation in minerals, or is decomposed,
to contribute to the formation of oils or other peculiar
juices of vegetables.
In the second place, water acts mechanically on plants,
by dilating them, and rendering them supple. The woody
fibre absorbs water abundantly, but not the bark. The
former is often so swelled by this absorption as to burst
and split the bark.
CARoline.—This is no doubt one of the causes of the
roughness of the bark of many trees, such as the oak
and the elm, which are so seamed and severed into small
parts.
MRs. B.—Yes; these, in the course of time, dry and
fall off. In other trees the bark remains smooth, but
peels off when split by the swelling of the wood.
EMILY.—But how can the wood absorb water if it
does not pass through the bark 7
MRs. B.—The wood absorbs water by the internal
vessels. If the trunk of a felled tree lie on the ground
in a damp spot, with the roots and branches cut away, so
as to leave the vessels exposed at both ends, it will absorb
so much water as frequently to make it sprout small
branches and leaves.
EMILY.—I recollect seeing an instance of this in Ken-
sington Gardens: the log was lying in a dell, partly im-
mersed in water, and the whole of it was sprouting with
verdure.
MRs. B.-Thirdly, water conveys air into plants; and
the more it is impregnated with air, whether atmospheric
or carbonic acid, the better it is adapted to vegetation.
Thus the water of large rivers which flow rapidly, and
pass over a great extent of country exposed to the influ-
ence of the atmosphere, is much more favourable to ve.
getation than that of small rivulets, which have not been
a sufficient length of time in contact with the atmosphere
to become impregnated with air : yet this latter is pre-
ferable to the water of a lake, which has no current; for
II
122 on THE ACTION OF WATER ON PLANTS.
it requires motion, and pretty strong motion, to mix water
and air together in the quantity which is required by
plants. Large lakes, such as that of Geneva, it is true,
are considerably agitated by the wind: the waves then
swallow up a certain quantity of air; but when tranquil
it contains much less than river water.
CARolisE.-Yet is not the water of ponds preferred
to that of rivers for watering plants, although it is so tran-
quil as frequently to become stagnant, and to be covered
with a green slime, which shows that it can have been
little agitated by the wind?
Mrs. B.-This green scum is a vegetable production,
affording food to numerous swarms of the insect tribe,
flies, worms, snails, &c. In a short space of time this
little ephemeral population, as well as the vegetables
which nourished it, perish, and putrefaction succeeds, as
you may frequently have discovered by the offensive
effluvia exhaled by ponds and marshes of this descrip-
tion; but the corrupted waters, disgusting and deleterious
as they are to us, afford a feast of abundance to the ve.
getable creation. Saturated with the decayed remnants
of both animal and vegetable matter, and replete with
carbonic acid, they convey these rich materials for fresh
vegetation into the roots of the living plant.
CARoline.—The only danger, then, is lest the fluid be
ºndently laden with food, and the plant be gorged
with it.
Mrs. B-As plants are not capable of acquiring the
virtue of temperance, Nature has wisely provided against
their suffering from excess, by giving them mouths of
such very small dimensions, that they cannot take in
more than is good for them. The only danger, therefore,
is, lest the fluid should be too dense to obtain entrance at
the roots.
The water least appropriate to plants is that of springs;
and, when obliged to use it, we should endeavour to re-
medy the double defect of a deficiency both of air and
of temperature, by leaving it exposed during some length
of time to the atmosphere. If the reservoir in which it
is contained be situated in the neighbourhood of a farm-

ON THE ACTION of water ON PLANTS. 123
yard or stables, the water will become impregnated with
carbonic acid evolved by the manure. , Advantage may
also be taken of such a vicinity to enrich the water of the
reservoir, by conveying a small stream through the ma-
nure into it.
Extrix.-But spring-water is not always of a lower
temperature than the atmosphere : during a frost it is
evidently warmer, being sheltered from the cold by the
depth whence it rises.
MRs. B.—Plants do not then require water: it is in
summer that this artificial aid is wanted, and never at a
season when the temperature of spring-water is higher
than that of the atmosphere.
ExILY.—One cannot sufficiently admire the beautiful
provision which Nature has made for watering her vege-
table creation. The rain, falling in small drops through
the atmosphere, acquires its temperature, and becomes
impregnated with air.
CAROLINE.—Yet rain-water can contain no nourish-
ment, unless it be a little carbonic acid it may imbibe from
the atmosphere in passing through it; for rain, consisting
of pure vapour exhaled from the surface of the earth,
can hold no nutritive particles in solution.
MRs. B.-Observe that, when rain falls on a plant, it
merely refreshes the foliage, by washing off the dust,
and cleansing the evaporating pores, which may have
been clogged during the drought. Rain cannot feed the
plant as it falls from the clouds; the absorbent pores,
you know, are not exposed to its influence; in order to
perform this second function it must penetrate into the
earth in search of food, and, dissolving whatever it meets
with appropriate for that purpose, convey it to the roots
of the plant.
Attention must be paid to the proper time and season
for watering plants. They do not require it at all in
winter, when growing in the open air; because, durin
that season, they cease growing, and, consequently, stan
in no need of nourishment; indeed, they often absorb
more water from the wet soil in winter than is good for
them. Green-house and hot-house plants should be wa-
124 ON THE ACTION OF WATER ON PLANTS.
tered with great moderation in winter: it is time enough
to supply them when they ask for it, which you may per-
ceive by their leaves beginning to droop and wither. As
spring approaches, the quantity of water must be in-
creased, in order to feed the young buds, which call up
additional sap ; but the increase must be made with pre-
caution, the earth being still moist with the winter rains.
Plants at this season should be watered in the morning,
in order that they may not be overloaded with moisture
during the night, which would be dangerous should a
frost chance to occur; besides, by watering in the morn-
ing, you provide for the evaporation of the day.
EMILY.—Yet our gardener generally prefers watering
in the evening, if he does it only once a day.
MRs. B.—In the midst of summer the plant, exhausted
by evaporation during the heat of the day, requires wa-
ter in the evening to revive it; there is then no danger of
its suffering from frost during the night. In Switzerland,
where heat and light are much more powerful than they
are with us in England, it is generally necessary to water
plants both morning and evening : the earth is dry; and
it is difficult in summer to provide for the immense in-
crease of the absorbing and evaporating functions.
There are some plants which grow perfectly well on
the Alps, because they are, throughout the summer, wa-
tered by streamlets supplied by the melting snow : these
same plants perish on the Jura, or any other mountain
which is free from snow in summer, because they are not
furnished with so regular a current of water.
In autumn, trees which bear pulpy fruits, such as the
peach and the plum, require a great deal of water to fill
out and to ripen the fruit. Fruits of a dry nature, such
as nuts and dates, do not need so much ; and the precau-
tion of watering in the morning is equally necessary as in
the spring, lest the plant should be surprised by a frost
during the night.
CARoline.—Grasses and herbs, I suppose, require
more water than trees; for consisting chiefly of leaves,
they must undergo a greater evaporation.
MRs. B.-Yes; and annual grasses the most of any,
oN THE Action of water on PLANTs. 125
Seeds which are beginning to germinate, should be
watered very sparingly; for the seed, feeding at first on
its own proper substance, is rather in want of air than of
water; but as soon as it has put forth roots, and a stem
has sprung up, it will require a more plentiful supply until
the time of flowering, when it must again be restricted,
because the blossom is nourished by its own peculiar
juices elaborated by the leaves; and when the seed ripens,
if it be of a dry nature, still less water must be given.
The quantity of water depends also upon the nature of
the cultivation. You must consider what is the produce
you wish to favour, and water accordingly: if it be a
meadow, leaves and not flowers will be your object;
therefore you must water profusely, since abundance of
water is favourable to leaves, and prejudicial to flowers.
If it be a field of corn, it is the grain you would favour;
therefore you must water sparingly. Rye is cultivated
sometimes with a view to the grain, and sometimes chiefly
for the straw; in the first case you must water but little,
in the latter abundantly.
The siliceous soil of Ireland is very favourable to the
culture of corn: this earth not being retentive of water,
the abundant rains of that country do not injure the crops.
A similar soil in France will not admit of the cultivation
of corn; because, the climate being much hotter, the
corn requires more water, and can be raised only on an
argillaceous or clay soil, which retains the water.
EMILY.-In watering fruit trees, I have observed the
gardener dig a trench round the tree, at some little dis-
tance fron the stem, and pour the water into it, instead of
watering close to the tree.
MRs. B.-A judicious gardener will apply the nourish-
ment to the mouths of the plant it is to feed. Now these,
you know, are situated at the extremity of the roots; and
as the roots spread out beneath the soil pretty nearly to
the same extent as the branches above the ground, the
tree should be watered at the distance of the extremity of
the branches from the stem; the closeness of garden
culture usually prevents a trench being dug so far from
the tree, but the nearer you approximate to it the better.
11*
126 ON THE ACTION OF WATER ON PLANTS.
Observe how admirably Nature teaches us this lesson:
the head of the tree, in the form of a dome, protects the
stem from the rain like an umbrella : all around, the soil
is exposed to the rain, and the water penetrates the earth,
just where the extremities of the roots are situated to
receive it. In addition to this, the greater part of the rain,
which has washed and refreshed the leaves, trickles down
from the ends of the branches, and reaches the ground in
the appropriate spot.
CAROLINE.-How beautifully contrived I shall not in
future take shelter from a shower, beneath a tree, without
thinking of it.
EMILY.—What strikes me with the greatest wonder, in
these arrangements of Nature, is the ease and simplicity
of the means employed: it is always a natural consequence
—a thing of course: it would require efforts to prevent,
rather than to produce such results: the facility with
which they are accomplished does not draw our attention;
but when we do observe and study them, we cannot but
feel their infinite superiority to the most complicated con-
trivances of art.
MRs. B.-The greater and more comprehensive the
mind that contrives, the more simple, in general, are the
means employed : you may admire, therefore, but you
can scarcely wonder at, the perfection of the economy
of Nature.
In order to form correct ideas on the theory of watering,
we must distinguish between the means which are natural
and those which are artificial. The former consists in
rain, dew, and the melting of snow. Since it is beyond
the power of Science to augment or diminish the quantity
of rain by a single drop, or to accelerate or retard, by a
single minute, the period of its falling; we must, with
great humility, limit our efforts to the study of the signs
of the times and seasons of approaching rain, in order to
modify our culture, so that it shall receive advantage and
not injury from it.
EMILY.-Does not the barometer indicate the approach
of rain with tolerable accuracy?
MRs. B.-Far from it: according to the most exact
ON THE ACTION OF WATER ON PLANTS. 127
calculations, it is found that the descent of the mercury
is followed by rain only seven times out of eleven.
CARolin E.-Then you have the hygrometer.
Mrs. B.-That is of little use as a sign of approaching
rain: it indicates merely the degree of moisture of the
spot in which it is situated, and gives us no insight into
the state of the upper regions of the atmosphere.
Wind blowing from places where a greater degree of
evaporation takes place, is one of the most unquestionable
precursors of rain. This is the case with winds blowing
from the sea; thus the west wind comes loaded with
vapour from the Atlantic Ocean, which it deposits on the
continent of Europe.
EMILY.—But why does the south wind bring us rain;
we may consider that as coming from the dry heated
continent of Africa, for the Mediterranean Sea is too
insignificant to impregnate it with vapour !
Mrs. B.-The climate of Africa being considerably
hotter than that of Europe, a greater evaporation takes
place there; the atmosphere dissolves and contains much
more water than our colder regions are capable of holding
in solution; the air, therefore, as it advances northward,
becomes loaded with a precipitation of vapour, which
congregates into clouds, and falls to the earth in the form
of rain.
CARol.1NE.—That is very curious; and a north wind,
on the contrary, being able to maintain more vapour in
solution in our climate than it did in the colder countries
whence it blows, scarcely ever brings us rain. I have
heard that swallows flying low, flies stinging, fowls rolling
themselves in the dust, and cattle feeding voraciously, are
all signs of approaching rain; pray, are these merely
rustic prejudices, or will they admit of an explanation ?
Mrs. B.—Swallows fly low before rain to catch the
insects, which then come nearer to the earth for shelter;
they may also approach the earth in search of worms,
which make their appearance above ground in times of
rain; then a species of fly, with an indurated trunk capa-
ble of inflicting a wound, frequently makes its appearance
on the approach of wet weather; fowls may possibly
128 ON THE ACTION OF WATER ON PLANTS.
cover themselves with dust in order to preserve them
from the wet; and cattle may, instinctively, lay in a store
of food as a provision against the time they must abandon
their pasture to seek shelter from the rain; but I do not
pretend to advance these opinions as any thing more than
conjecture, founded on some appearance of plausibility.
The second mode which Nature employs to water plants
is the dew. I hope you recollect the very ingenious
theory of Dr. Wells on that subject.
ExiILY.—I fear but imperfectly.
Mrs. B.-I advise you to look it over;” at present I
shall only say that it is founded on Professor Prevost's
Theory of Radiant Heat. In proportion as a body ra-
diates, its temperature must necessarily be lowered, unless
it be supplied with heat from some foreign source : during
the day the sun affords this supply very amply; but after
sunset the earth, as well as every object upon its surface,
cools by radiation. The atmosphere, which radiates
much less than the solid earth, preserves its temperature
longer; but the stratum of air which is immediately in
contact with the ground is cooled by it, and deposits upon
it that portion of vapour which the diminution of its tem-
perature prevents it from longer holding in solution. This
precipitation is the dew which you perceive on the grass
after sunset.
ExILY.—Since it proceeds from the cooling of the
surface of the earth, why is it not equally precipitated on
gravel walks and pavement 1
MRs. B.-Because the stones of which these are com-
posed are not good radiators, and therefore preserve their
temperature longer; and if they do not cool quicker than
the air with which they are in contact, no deposition of
dew will take place. Minerals, and especially metals,
are bad radiators; they require no dew : Nature reserves
this mode of watering for the vegetable creation : to plants
she gives the power of abundant radiation, both to enable
them to throw off the heat with which they have been
oppressed during the day, and to call down those refresh-
ing showers of dew which restore their vigour. One
* See Conversations on Chemistry, vol. i. p. 99.
ON THE Action of water on PLANTs. 129
knows not which most to admire, the wise provision which
is thus made for the benefit of the vegetable kingdom, or
the simplicity of the means by which it is accomplished.
CARoll.S.E.-I imagined that the dew fell from a con-
siderable height; for trees afford a shelter from it: you
seldom find any dew beneath a tree.
MRs. B.-The radiation of the earth is stopped by the
canopy of the tree and reflected back to the ground, thus
preventing it from so rapidly cooling as to occasion a
deposition of dew. For the same reason, when the sky
is covered with clouds, the heat is reflected back to the
earth by them, and little or no precipitation of dew takes
place ; while, on a clear night, the radiation goes on
uninterruptedly, the earth cools rapidly, and an abundant
dew is deposited.
EMILY.—How admirably this provision is proportioned
to the wants of the vegetable creation . A clear sky,
which leaves it exposed throughout the day to the ardour
of the sun's rays, insures it an abundant supply of refresh-
ing dew in the evening.
CARoline.—I have seldom perceived this radiation of
heat in England, but in Switzerland it is very sensibly
felt on a summer's evening, from trees, walls, and other
buildings which have been heated by the sun during the
day. 4)
MRs. 3.-It is for this reason, that, in hot climates, the
public walks are less planted with trees, than those of
more temperate regions; in the former you can walk
out only after sunset, when the neighbourhood of trees is
attended with every disadvantage. They prevent the
free circulation of the cool evening air. They reflect
back the heated radiation of the earth, and are, them-
selves, a source of heat by their own radiation.
EMILY.—In our more temperate climate, when we fre-
quently walk out during the day, trees afford us a grate-
ful shelter from the sun, and in the evening they have the
ady antage of retaining the heat and preventing the depo-
wition of dew.
MBs. B.-In regard to the third mode which nature
1.30 ON THE ARTIFICIAL MODE.
employs to water plants, the melting of snow, as it relates
only to plants growing on the Alps, or other mountains
whose summits are constantly covered with snow, it is
unnecessary to make any observations upon the subject.
CONVERSATION XI.
ON THE ARTIFICIAL MODE OF WATERING IPLANTS.
MRs. B.-We shall now proceed to examine the artifi-
cial modes of watering, which may be divided into three
classes.
1st. By watering-pots or engines.
2d. By filtration.
3d. By irrigation.
The first mode applies merely to horticulture, for the
use of watering-pots can scarcely be extended beyond
the garden and green.house; the plain spout is calculated
for watering the roots, that pierced with holes for washing
the leaves, and for watering seeds, young sprouts, or de-
licate plants which require to be watered sparingly.
If the soil be light, or the plants situated near the high
road, or exposed to the smoke of a town, they require
more water to refresh the leaves; for if the stomas are
choked, evaporation is checked, and vegetation injured :
in order to render your plants healthy, they must not only
be well fed, but kept clean.
Exilly.—Green-house and hot-house plants being shel-
tered from the dust, will, I suppose, not require so much
precaution?
Mrs. B.-On the contrary, they are exposed to the
dust which arises from their cultivation within doors, and
deprived of the natural means of getting rid of it, the
wind, which in the open air prevents the dust from accu.
mulating on plants: this artificial mode of raising plants,
therefore, requires more attention to cleanliness than
when grown in the open air; and gardeners frequently
use a bellows as a substitute for the wind.
CAROLINE,-Is it not a good way of keeping green-
OF WATERING PLANTS. 13|
house plants moist in the summer to bury them in their
pots in the earth?
MRs. B.-Yes, provided they are taken up occasion.
ally, in order to cut off the roots, which shoot through the
aperture at the bottom of the pot; for if this operation
be delayed till they are housed in the autumn, the roots
will be so bulky as to render their amputation dangerous.
CARoline.—Yet is it not the nourishment which the
plant obtains from the soil, by shooting its roots through
this aperture, which gives it so much vigour?
Mrs. B.-True, but the small fibres which sprout out
after cutting away the projecting roots are sufficient for
this purpose. The main object of the aperture at the
bottom of the vase, is in order that the water may filter
through ; without this resource it would become stagnant
around the roots, and rot them. The opening is, you
know, partially closed by a piece of tile, leaving not
more room than for the water to escape which is not ab-
sorbed by the roots; but when water is not supplied to
the plant in sufficient quantity, the fibrous roots insinuate
themselves through the aperture to search for it in the
soil beneath.
Watering by filtration is adapted to two classes of
plants; those which suffer from excess, and those which
suffer from scarcity of water : it may be performed in
two ways, the one is by enclosing the vase which con-
tains the plant, in a larger one full of water, and then bu-
rying the double case in the earth, the water will filter
from the outer into the inner vase, which must not, of
course, be glazed, but of a porous texture. The other
mode is to place a pot of water contiguous to that which
contains the plant, and connect them by means of a skein
of worsted which will act as a syphon, and transfer the
water to the vase in which the plant grows.
In the Isle of Corfu I have heard that it is usual to wa-
ter the orange-trees by surrounding them, at the distance
of the extremities of the roots, with very porous pots of
water; the water oozes through into the ground, and is
sucked up by the spongioles.
Meadows are commonly watered by filtration, small
132 ON THE ARTIFICIAL MODE
trenches are dug, into which water is occasionally made
to flow, and thence it filters into the adjacent soil; these
trenches should be rather below the surface of the soil,
in order that the water may the more easily penetrate to
the roots of the grass.
EMILY.—The trenches are, I suppose, left open in or-
der that the water may derive the benefit of exposure to
the air 7
MRs. B.-They are sometimes buried in the soil, and
at others left open. The first have the advantage of
economising the soil, as the ground above them may be
cultivated; loss is also prevented by evaporation: yet I
prefer the open trenches, both on account of exposure to
he air and as affording facility for repairs, which are
often required.
3dly. Watering by irrigation consists in conveying the
fluid through small channels similar to those used for wa-
tering by filtration, but which are made, at pleasure,
to overflow the adjacent ground. In order to accomplish
this, it is necessary to be furnished with an ample supply
of water; if it can be obtained from a superior elevation
the operation is greatly facilitated.
When, on the contrary, it is necessary to raise it from
rivers or wells, various mechanical means may be re-
sorted to. The current of a river may be used to turn a
wheel furnished with small buckets, which, during one
revolution of the wheel, fill with water, raise it, and pour
it into the reservoir prepared to supply the rivulets of
irrigation: when there is no current, horses may be em-
ployed to turn the wheel.
The hydraulic ram is another mode of raising water.
M. De Candolle mentioned one, which, put in motion by
a fall of water of twenty feet, raises a body of eight
cubic feet per minute to the height of one hundred and
sixty feet.
EMILY.—I should think a steam-engine would afford
...the most effectual means of raising water; is it not used
for this purpose ?
MRs. B.-Very frequently, for draining mines; but it
would, I conceive, be too expensive a mode of raising
OF WATERING PLANTS. 133
water for the purpose of agriculture; at least, I never
heard of it being so applied.
lt is to be regretted that the rain water which is washed
down from the roofs of houses should not be turned to
account; soiled as it is by this operation, it would but be
the better calculated for the nourishment of plants; and
it might easily be collected into a reservoir, instead of
being carried off, as it usually is, by the common sewer.
It is singular that we should have first learnt artificial
modes of watering from the Moors of Spain; their
labours in that department were very extensive. Near
Alicant they constructed a wall between two hills in order
to retain the water which flowed through the valley, for
the purpose of irrigating the adjacent country. This
wall, which is still in existence, is only twenty-four feet
in length at the base, this being the breadth of the valley;
but the hills receding as they rise, it is two hundred and
sixty feet long at the top, and sixty-seven feet in depth;
which is much more than is required to withstand the
force of the waters it confines; but the Moors were not
versed in the laws of hydraulics.
There are various modes of irrigation: the inundations
are sometimes flowing, sometimes stagnant; sometimes
transitory, at other times permanent, according to the na-
ture of the culture. Of the latter description are the
rice plantations: this plant requires such abundance of
water, that the inundation is drawn off only when the
grain begins to ripen.
ExILY.-I remember, in Lombardy, seeing the green
tops of the rice peeping through their watery bath, and
looking not very unlike the green scum which frequently
covers pools of stagnant water. Nor does it appear to
be less pernicious; for I have heard that the cultivators
of these rice fields are often afflicted with a frightful cu.
taneous disease, which terminates frequently in madness
and self-destruction.
MRs. B.—The cultivation of rice is certainly not a
healthy employment, owing to the stagnant waters in
which it is raised; but the disease to which you allude,
called the Pelagra, is supposed to proceed from feeding
12
134 ON THIE ARTIFICIAL MODES
on maize, or Indian corn, improperly prepared. The
origin of this dreadful malady was for a long time an in-
explicable mystery; and it is only lutely that Dr. Sette
observed that it was confined to those districts in which
the maize, instead of being preserved in the ear, was
kept, like wheat, in separate grains, ready to be ground
into flour. This led him to suspect that the grain might
have acquired some deleterious property; and, on exa-
mining it with a microscope, he discovered that that part
of the grain, by which it had been attached to the husk,
was covered by a species of mould of a poisonous na-
ture; there is, therefore, every reason to believe that this
fatal disease arises from feeding on maize in this corrupt
state; and if so, the disease might be easily guarded
against.
ExIILY.—What a fortunate discovery ! The remedy
is so simple, it is merely to adopt the usual mode of pre-
serving maize in France and Switzerland, by hanging it
up to dry in the ear.
MRs. B.-Certainly. We have hitherto considered
only the various modes of administering water; but it
sometimes happens that the earth is too moist: it is ne-
cessary, therefore, for the purposes of agriculture, to be
acquainted with the best mode of draining it. This ope-
ration may be performed in several ways. When the
locality will admit of constructing a reservoir in a lower
situation to receive it, the water may be carried off by
subterranean ducts. These conduits should be filled with
pebbles, sufficiently large to leave a free passage for the
waters between them.
CARolisE.—But of what use are the stones? why not
leave the channel quite free and open 7
MRs. B-The stones may be considered as forming a
sort of loose wall which serves to support the duct, by
preventing the top and sides from falling in : the water
would soon wear them away, were they not thus defended,
and the passage be obstructed.
The operation of draining a marsh is of much greater
importance. A marsh is a space of ground on which the
water remains too long, either for want of means of runs
OF WATERING FLANTS. 135
ning off laterally, or because a layer of clay soil prevents
it from filtering downwards.
CARoline.—I should have thought that this abundance
of water would have been favourable to the culture of
many species of plants.
Mrs. B.—It is true that marshes cannot be said to be
inimical to vegetation in general; for these spots abound
with plants, but they are of an aqueous nature, which are
good neither for man nor cattle. They afford, however,
an ample repast for the creeping things of the earth ; and
when we condemn noxious weeds and stagnant marshes,
we should remember that, though man is lord of the cre-
ation, this world was not made for him alone, and that the
reptile and the worm have also their share of its enjoy-
ments. When it is required to drain a marsh of small
extent, it may be done by planting it with willows, alders,
and poplars. These trees being of very rapid growth
absorb a considerable quantity of water, the greater part
of which they evaporate into the atmosphere. The pop-
lar has also the advantage of affording very little shade ;
it does not, therefore, interfere with the action of the sun
and air, agents which perform very prominent parts in
the operation of draining.
Very extensive marshes will not admit of being drained
merely by planting. In this case, the mode resorted to
is to raise a bank of earth around the marsh, which an-
swers the purpose of a dam, and prevents the water from
running into it; for, if once you accomplish this, the
marsh is soon dried by the mere process of evaporation.
If the marsh be occasioned by a clay soil, the argilla-
ceous earth, which does so much harm by retaining the
water after it has entered the marsh, will do as much
good by its impermeability when raised in the form of a
bank to prevent the water from entering. In digging for
this purpose, the earth must be thrown up towards the
marsh, so as to leave the trench or ditch external; the
water will then run off by this ditch instead of filtering
through the dam raised on the other side. The dam
should be formed in the shape of a hog's back, and
pressed down hard towards the base, in order to prevent
136 ON THE ARTIFICIAL MODES
the water in the ditch oozing through. The dam or dyke
may be planted with trees, the roots of which will help
to keep it together, and the evaporation by the leaves will
assist in draining it: but care must be taken to thin the
branches, in order to give free access to the sun and
wind; nor must they be allowed to grow high, lest the
wind, having too great a hold of them, should loosen the
roots, and thus injure, instead of preserve, the dyke. On
the side next the ditch it is advisable to plant reeds.
ExILY.—But how are you to get rid of the water which
ſills the ditches'ſ
Mrs. B.-That depends, in a great measure, upon the
locality: it must be carried off to the nearest running
water, or to the sea; without a resource of this kind, it
would be vain to attempt to drain a marsh. If we can
succeed in preventing the external waters from gaining
admittance, that which the marsh contains is so soon
dried up by evaporation, that care must be taken not to
overshoot the mark, and leave an insufficiency of mois-
ture for the purpose of cultivation.
CARoline.—Some attempts of this kind appear to have
been made towards draining the Pontine marshes; a ca-
nal of water borders each side of the road, which is
flanked by a bank of earth planted with trees; and when
we passed, I saw, with regret, that they were cutting
most of them down.
Mrs. B.-It was probably found, that more injury was
produced by their shade, than benefit derived from the
evaporation of their leaves. But this attempt at draining
the Pontine marshes is of a very circumscribed nature,
and attended with little success; although the vicinity of
the sea affords facility for carrying off the water, the dif.
ficulty of draining these marshes has never yet been sur-
mounted.
When marshes are situated below the level of the sea,
as is generally the case in Holland, to drain them is a
very laborious undertaking, and requires all the patient
persevering industry of the Dutch to accomplish. They
begin by making the water run off into canals, and then
raise it, by mechanical means, into more elevated chan-
nels, till it attains an elevation above the level of the sea.
OF WATERING PLANTS, 137
gº
CARoline.—But the level of the sea varies according
to the tides, being many feet more elevated at high water
than at ebb tide 1
MRs. B.-The medium must therefore be taken as a
general level; and raising the most elevated canals above
that, let off the water at ebb tide into the sea: the canals
are furnished with locks, which are then closed, to pre-
vent the water returning when the tide flows. The mode
used in Holland to raise the water from the lower to the
upper canals consists of a species of small windmills :
as the wind blows regularly, though not violently, in that
country, they perform their office very well. The same
process of windmills is adopted in Cambridgeshire and
Bedfordshire.
EMILY.-Pray can you explain to us the mode in
which the valley of Chiana in Tuscany, which was an-
ciently an unwholesome marsh, has been brought to such
a beautiful state of cultivation as it now exhibits?
MSR. B.-The marshes in Tuscany are formed by the
waters which flow from the Apennines, and which, not
finding a sufficient vent, are arrested in their course, and
become stagnant. The Apennines being of a loose sandy
texture, the waters bring with them a great quantity of
earth, which they deposit in the lowest parts to which
they flow.
CAROLINE.-I recollect that the Arno, when swollen
by rain, is quite thick with mud, brought down from the
unountains by the torrents which feed it.
MRs. B.-The celebrated Torrecelli took advantage of
the deposition of this mud to invent a mode of draining
the march of the Chiana. But before I explain the
remedy, it will be necessary to inform you whence the
evil arose, and give you an account of the origin of this
marsh.
In ancient times the numerous rivulets which flow from
the adjacent hills into the valley of Chiana poured their
united waters from thence into the Tiber. Some incon.
venience being experienced by the Romans, from occa-
sional overflowing, they constructed a dyke to close this
outlet. The waters, thus stopped in their course, formed
12*
138 ON THE ARTIFICIAL MODES
a lake, which, when raised by accumulation to a certain
elevation, found an issue to the north, precisely in the op-
posite direction to that in which the water formerly flow-
ed out of the valley. The rivulets, therefore, on entering
the valley, were all obliged to change their course. In
making this turn, their velocity was diminished; and
having no longer power sufficient to carry with them the
earthy materials with which they were laden, these were
deposited in the lake, in which they accumulated, and, in
the course of time, converted it into a marsh. The in-
genious and sagacious Torrecelli availed himself of the
evil to devise a remedy; and employed the verv means
which had converted the lake into a marsh to convert the
marsh into dry land.
FMILY.—That was a most happy idea ; but how did he
accomplish it !
Mrs. B.-He caused a mound or bank of earth to be
raised towards the base of the hill, around the part where
a rivulet changed its course. This was left open on the
most elevated side ; so that the water, laden with earth,
in its descent might have free access to it; on the lower
side a small aperture was made through which the water
alone could escape, leaving behind the earthy matter,
with which it was saturated. In the course of time, the
soil within the enclosure, was elevated by the accumula-
tion of earth, above the level of the stagnant waters;
and rose, like a dry little island, on the edge of the
marsh. A contiguous enclosure was then made, and
raised by similar means ; a third and a fourth followed in
succession. These labours have been going on during
two centuries: of late years they have been prosecuted
with great activity and sagacity by the celebrated Fosom-
broni of Florence; and only a few years more will be
required to complete them. Already you have beheld
this district transformed, from a melancholy and pestilen-
tial marsh, into a richly cultivated valley, watered by
a clear stream, the result of the torrents purified from
their earthy deposits.
CARo11NE.—It is, indeed, quite a metamorphosis; and
is not this mode adopted in other countries?
OF WATERING PLANTS, 139
Mrs. B.-It is frequently employed in the environs of
Bologna, and in several other parts of Italy. This ope-
ration is called in Italian colmare, in French combler, that
is to say, to fill up. I once, in travelling, saw it carrying
on, in a spot on the declivity of a hill; for you under.
stand that it can take place only where the ground slopes,
so as to enable the waters to run off.
CARolisE.—When the mountains, from which the
rivulets bring down the earth are of schist, like the Apen-
nines, this operation must be much more easily effected
than when they are of granite, for the harder the earth
the less earthy matter the waters can wash down.
MRs. B.--When the mountains are of granite, no de-
position of earth takes place to interrupt the course of the
streams, and produce a marsh : the evil cannot exist, and
the remedy is not required.
EMILY.—But elaborate and artificial as this mode ap-
pears, it is, in fact, precisely that which Nature employs
to level the inequalities of the globe: the streams are
ever conveying earth from the mountains to deposit it in
the valleys, thus lowering the one and elevating the
other.
Mrs. B.-That is perfectly true : it is thus that the
plains in the north of ltaly, between the two ridges of the
Alps and the Apennines, have been formed. The rivers
flowing from these long chains of mountains have deposit-
ed their solid contents in the intervening low lands, raised
and united the several vallies, and levelled them into
plains, such as those of Lombardy and Liguria; and,
had Nature been allowed time to complete her work, they
would have been elevated to a height which would have
preserved them from danger; but impatient man was
eager to inhabit this alluring paradise, before its creation
was completed. Hence, instead of profiting by the gra-
tuitous labours of Nature, who wss gradually preparing it
for his reception, he has been compelled to repair by ar.
tificial means, at the expense of immense toil and trouble,
the evils resulting from the interruption given to her ope-
rations.
FxiILY.—But of what nature are those evils 7
140 ON THE ARTIFICIAL MODES, ETC.
MRs. B.-Inundations produced by the quantity of tur-
bid waters, which in rainy seasons, is frequently so great,
as to overflow the whole country, and destroy cultivation.
The inhabitants, therefore, found it expedient to put a
stop to this levelling system of Nature by embanking the
rivers, in order to confine the waters within their beds.
CARoline.—We observed that in Lombardy and in
Tuscany the rivers were generally embanked : but I
should have thought that such a measure would have af.
forded but a temporary remedy; for those very sands,
which Nature would have employed to raise the general
level of the plains, being deposited at the bottom of the
rivers, would in the course of time, so raise their beds,
that the waters would overflow the embankments.
Mrs. B.-Very true; their only resource was to raise
the embankments in proportion as the beds of the rivers
were elevated. In consequence of this elevating system
of art, in opposition to the levelling one of Nature, the
Adige and the Po are higher than the plains which sepa-
rate the two rivers ; and it is thought that it will be ulti-
mately necessary to form new beds for their waters, in
order to avoid the ruin they threaten.
The plains of Holland derive their origin from a simi-
lar process; but they are exposed to still greater dangers
than those of Italy, lying so low as to be menaced not
only by the overflowing of the Rhine and the Moselle,
from the shallowness of their beds, but by inundation of
the sea. Every defence which art can afford, such as
embankments, dykes, canals, &c., has been achieved by
the patient and industrious inhabitants of that enterpri-
sing country; yet the resistless ocean frequently breaks
in upon them, and destroys all their labours.
ExILY.—What a prodigious quantity of earth and sand
these rivers must carry into the sea! It is well that its
bed is too deep, to be affected by such depositions. ſº
MRs. B.—It is true there is no danger of their occa.
sioning an overflowing of the sea: important effects,
however, are frequently produced on its shores. The
impulse of the rivers is diminished on reaching the sea.
by that of the waves they have to encounter. Sometime."
ACTION OF THE SOIL ON PLANTS. 141
their waters are partially repelled back on the shore,
where they form marshes: districts of this description
abound on the coast of the Adriatic. Sometimes they
deposit their solid contents in one large bank, when their
current is first repulsed by the waves of the sea, and
form at the mouth of the river a plain or Delta: such is
the Delta at the mouth of the Nile.
CARoll NE.-And if we may be allowed to compare
small things to great ones, such I suppose is the origin of
the Delta or low land, at the mouth of the Rhône, on en-
tering the Lake of Geneva from the Valais. And the
Isle of Camarque, formed by the deposition of the waters
of the Rhône at its entrance into the sea, offers a still
more striking example.
MRs. B.-Sometimes, the rivers have sufficient power
to struggle against the resistance of the waves, and do
not deposit their mud and sand, till they have advanced to
some little distance in the sea; when their waters, broken
and divided by the waves, precipitate their cargo in sepa-
rate spots, forming a number of small islands; hence the
origin of those on which Venice is built.
We have prolonged our conversation rather beyond
bounds to-day; I have but one more remark to make to
conclude this subject. i-
When it is required to resist the force of an irregular
mountain-torrent, a number of small embankments is pre-
ferable to one large dyke, however strong; for during
violent rains there is some danger of the dyke being car-
ried away, while several small embankments successively
break the force of the waters.
CONVERSATION XII.
ON THE ACTION OF THE SOIL ON PLANTS,
Mrs. B.-Our last conversation was upon water: to.
day we shall change the subject to dry land. It has been
asserted, that earth was not absolutely essential to vege-
142 ACTION OF THE SOIL ON PLANTS,
tation, because there are some plants which do not re-
quire it, which live in water, whence they derive their
nourishment: but this class is very insignificant. The
earth affords both support and nourishment to plants.
CARoll NE.-Or shonld you not rather say, is the vehi-
cle of their nourishment, since their food is composed
principally of animal and vegetable remains?
MRs. B.-Very true; the various saline particles which
plants pump up from the soil, should rather be considered
as flavouring their food, than forming a nutritive part of
it: their daily bread is of animal and vegetable origin.
CARolls E.-And when there is a deficiency of salts to
flavour their food, have not plants the power of forming
them in their internal laboratory !
Mrs. B.—No ; the chemical apparatus of their organs
is so arranged that it can elaborate only vegetable juices,
and is as incapable of forming a salt or an oxide, as an
animal is of forming the phosphat of lime, with which its
bones are indurated.
EMILY.—How then are these salts, which are com-
posed of various ingredients, formed !
MRs. B.—The metals intermixed with the earths of
which our globe is composed attract oxygen from the at-
mosphere, and combine with it; and it is thus that the
mineral kingdom prepares the oxides, for the use of or-
ganised bodies.
The earth, we have said, supports plants, and gives
them a fulcrum or point of rest, which animals have not,
because they do not require it. In order to support plants,
the ground must be neither too compact nor too loose.
They cannot grow upon a hard rock, nor in a moving
sand ; their roots cannot penetrate the first, nor take firm
hold on the latter.
EMILY.—Besides, a plant would find no food to nourish
it on a barren rock.
MRs. B.-That most patient and persevering of agri-
culturists, Nature, teaches us how to prepare a soil, even
on the hard rock, or the sterile lava of a volcano ; she
commences her preparations on these obdurate bodies
ACTION OF THE SOIL ON PLANTS, 143
by means of her elementary agents, air and water. If
the rock be of a calcareous nature, the lime is gradually
dissolved, a decomposition begins to be effected; and
hence the origin of a soil. If the rock be selicious the
operation is more difficult; but Nature, unrestricted b
time, finally accomplishes her object. On this shadow
of a soil, a vegetation, almost imperceptible from its mi-
nuteness, begins to exist: the invisible seeds of lichens,
which are ever floating in the air, there find an asylum.
Minute as these seeds are, they are furnished with admi-
rable means to attach themselves to hard bodies.
CARoline.—What a careful provision Nature has made
for the most insignificant of her vegetable kingdom'
MRs. B.-These seeds, once attached to the rock, find
sufficient nourishment in the moisture they have absorbed
from the atmosphere during their aerial flight to enable
them to germinate, but not sufficient to bring them to per-
ſection, and enable them to produce seeds to continue
their species; but when they perish, a new race rises,
phoenix-like, from their remains.
EMILY.—This is indeed a new mode of raising plants!
MRs. B.-It is these remains, mixed up with some of
the crumbled particles of the rock, which constitute the
first bed of earthy soil, in which the seeds of more robust
lichens and mosses sow themselves, and find nourishment;
thus a variety of plants, annually increasing in strength
and vigour, rise up in succession, till the dry rock becomes
covered with verdure, and ultimately clothed with trees.
You see, therefore, Caroline, that you have no more rea-
son to despise the humble plants in whose remains a soil
originates, than to underrate the germ of a shoot which
may produce a stately oak.
There is another process which Nature frequently em.
ploys to clothe a barren rock: wherever there are fissures
the rain insinuates itself, and by freezing in winter often
splits the rock, or at least widens the crevices; it is in
these humid recesses, where the water has crumbled the
rock, that seeds bury themselves, and vegetation com.
mences.
ExILY.-In attempting, then, to cultivate a barren soil;
144 ACTION OF THE SOIL ON PLANTS.
we should follow those lessons which Nature points out,
and scatter seed in such crevices, which, if they did not
arrive at complete maturity, would, by their remains at
least, help to prepare a soil.
MRs. B.-This is often done; for instance, in the fis-
sures of the lava of Mount AEtna. Indian fig or prickly
pear has been sown ; the roots of which insinuate them.
selves into every little cavity, and help to split the block.
This plant produces a great quantity of fruit, but its most
important recommendation is, that of forming a soil for
future vegetation; but to proceed to soils of a less obdu-
rate nature.
A stiff argillaceous soil is difficult to cultivate, on ac-
count of the resistance it opposes to the penetration of
roots. This description of soil attracts moisture, and is
so retentive of water as to be seldom dry, unless during
the heat of summer, when it splits; and it is in the crevi-
ces thus formed that vegetation commences. Such a soil
requires frequent ploughing, in order to break down and
pulverise the clods; when practicable, earth of a lighter
nature should be mixed with it. Plants having large roots
will not, in general, succeed in a soil of this description,
as they will not be able to penetrate it.
ExIILY.—Yet plants with small delicate roots will have
still less strength to do so.
MRs. B.-True ; choice should therefore be made of
plants which have slender, but firm and strong roots :
those whose roots are of a dry nature are best adapted to
hard, impenetrable soils.
A sandy soil offers difficulties of an opposite description.
If the sand be mixed with calcareous matter, these are
more easily overcome; for a portion of the lime is dis-
solved by rain, and its solution gives some degree of sta-
bility to the soil: but if the sand be almost entirely silici-
ous, like that of the sea, the evil is well nigh insuperable :
for this species of sand is insoluble, and nothing can
change its nature. Hence the impracticability of cultiva-
ting the sandy deserts of Arabia, Africa, and various other
parts of the world.
Exilly.-Yet, if such deserts existed in Europe, do you
ACTION OF THE SOIL ON PLANTS. 145
not think that means would be discovered to overcome
the difficulty
MRs. B.—I doubt it. The wind which blows without
restraint over these unsheltered and unstable plains tears
up the roots of every tree that is planted.
ExILy.—But small low shrubs would offer but little re.
sistance to the wind.
MRs. B.—These would soon be buried by the whirl.
winds of sand. The plants most likely to succeed would
be such as are of moderate stature, with spreading roots
to fix them in the soil.
When sands are of small extent they may be improved
by mixing clay with them; and the first crop should be
raised solely with the view of meliorating the soil.
There are three species of sandy soil : that which
forms the banks of rivers; that which composes those
extensive plains called steppes; and that which forms
sand-hills on the sea-shore. On the borders of rivers,
stakes of willow and of alder may be planted with advan-
tage ; being abundantly watered, they soon shoot out
roots and branches, which grow rapidly. Then, if with
the stroke of a hatchet these branches be lopped, so as to
make them trail upon the ground, without being completely
separated from the stem, they will soon be covered with
the loose soil and will strike fresh roots: these numerous
roots shooting out in every direction, are interwoven, and
form a species of net-work, which sustains and gives sta-
bility to the soil.
In order to bring steppes into culture, which are not so
well supplied with water, the first plants raised must have
roots which pierce deep into the earth, so that they may
find water beneath the sandy soil. The culture of madder
has been successfully employed in the neighbourhood of
IIaguenot, as the precursor of general agriculture. It
cannot be too often repeated, that when you aim at bring-
ing bad soils into culture, the first produce must be sacri.
ficed for the benefit of the land, with a view to improve
it for future harvests.
CARoline.—So far as can be judged from the abun-
dance and magnitude of the crops, Belgium appears to be
13
146 ACTION OF THE SOIL ON PLANTS.
one of the countries in which agriculture is carried to thc
greatest degree of perfection.
MRs. B.-The beauty of the produce is no bad crite-
rion of the advancement in the art, especially in Belgium,
where Nature has done little for the husbandman; but the
Belgic peasantry are nearly as well versed in agriculture
as the learned of other countries. Their soil is in a great
measure the work of art, man having taken possession of
it before Nature had completed its formation.
CARoll NE.-Nor does it appear that the art of man has
yet finished it; for though the cultivated parts yield such
rich crops, an extensive sandy desert, called the Campine,
still remains on the confines of Belgium and IIolland.
MRs. B.—True ; but cultivation advances with gigantic
strides across the arid waste. The mode by which the
husbandman commences the process of fertilisation in
these sterile plains is by sowing Genet or Broom, which
grows up in bushes, the roots of which confine the soil,
and give it sufficient stability to enable him to sow pines
with advantage. These are followed by Acacias; the
branching roots of which, stretching out in various direc-
tions and interwoven toget, er, sustain the soil as it were
in osier baskets. But it is not until this succession of
forests have ſlourished and decayed, that the soil, enriched
by their remains, becomes fit for general culture.
EMILY.—This, then, is the work of a long course of
years 7
MRs. B.-Certainly ; but still the formation of the soil
is rapid, in comparison of what it would have been, if left
to be completed by the gradual agency of Nature, who is
enabled to prolong her operations beyond the period of
our transitory existence, and is therefore less impatient to
accomplish her task. We are justified, however, in taking
it out of her hands, if we can produce the effect more
rapidly. The sand-hills, which are, in many places, form-
ed on the sea-coast, owe their origin to sand thrown up by
the high tide, and which, abandoned by the receding
waters, dries, and is carried by the wind farther inland,
and out of the reach of successive tides. The sand-hills
formed in the vicinity of Bourdeaux, formerly threatened
ACTION OF THE SOIL ON PLANTS. 147
the destruction of the adjacent country: it was calculated
that no less than seventeen villages would be overwhelmed
by them in the course of a century, when M. Bremon-
tier was so fortunate as to discover a means of averting
this danger. Observing that sand thus thrown up was
not devoid of moisture, he scattered over it the seeds of
broom and of maritime pine ; and, in order to prevent
their being swept away by the wind, he covered them with
brambles and branches of underwood. The seed sprout-
ed; the broom first rose above ground, and sometime after
the young pines appeared : the latter, however, made but
little progress, seeming to be choked by the rapid growth
of the broom; yet in the course of a few years the pines
gained the ascendency, and drove their antagonists from
the field; or rather, I should say, like true cannibals,
after destroying the enemy, they fed upon their remains.
In the course of time it became necessary to thin this
vigorous forest of pines; and their branches served to
shelter the seed scattered on neighbouring sand-hills.
CARolix.E.—I recollect reading in Withering, that the
Arundo arenaria, or sea-matweed, which grows only, on
the very driest sand on the sea-shore, prevents the wind
from dispersing the sand over the adjoining fields. The
Dutch have very probably known and profited by this fact.
MRs. B.-Hitherto we have directed our attention
rather to the formation of new soils than to the improve.
ment of old ones : yet the latter is the point of most im-
portance in agriculture; for we are much more frequently
called upon to meliorate the land already under tillage
than to prepare a soil, on land which has not yet yielded
any produce.
Soils may be improved by a variety of different pro-
cesses : by tillage, by amendments, by manure, and by
rotation of crops.
These follow each other in natural succession. Man
first begins by cultivatiug the earth; he next endeavours
to meliorate the soil, in order to render it more propitious
to the produce he wishes to raise. After having yielded
a certain number of crops, he observes that the earth is
exhausted of its nutritive principles, and that the crops
are poor and meagre. IIe finds the means of renovating
148 ACTION OF THE SOIL ON PLANTS.
these principles by manuring the land; and, when manure
falls short, he discovers that a judicious system of crop-
ping answers, in a great measure the same purpose.
The principal object of tillage is to break and crumble
the earth, in order that the roots of young plants may
easily penetrate into it; to expose every part of the soil
successively to the action of the air, so that such of the
earths or metals, as are destined to be converted into salts
by the action of the oxygen of the atmosphere may be
brought into contact with it, as well as such remains of
organic bodies as can be dissolved only by oxygen. Wa-
rious implements of husbandry are employed for this pur-
pose ; and it is a continual object of dispute, between the
agriculturists of different countries, which answers the
purpose best.
EMILY.—But is not the plough the instrument universal-
ly used in all civilised countries 1
MRs. B.—Most commonly; but the plough itself is of
various descriptions, and you have observed the peasantry
of Tuscany frequently employing the spade, an imple-
ment which we reserve for garden culture. They are,
indeed, bound by the tenure on which they hold their land
to dig it up every third year. The spade undoubtedly
performs the operation of turning and subdividing the
earth more completely than the plough, but at a much
greater expense of labour; and it is an instrument adapt-
ed only to light and homogeneous soils, for if the earth
be of unequal tenacity, or interspersed with stones, it
cannot be used. The pickaxe may in these cases be
substituted, as it is a pointed instrument, which more
easily penetrates. This implement is also of various de-
scriptions : it has a single or a double prong, which is
broader or sharper, and forms a greater or lesser angle
with the handle, according to the nature of the soil.
With the spade the labourer works backward, and
throws up the earth before him; with the pickaxe he goes
forward, and draws the earth towards him.
CARoline.—The hoe, that very useful instrument for
weeding or lightly raising the earth, is also used like the
pickaxe. But what is the reason that the form of these
instruments vary so much, in different countries 7
ACTION OF THID SOIL ON PLANTs. 149
Mrs. B.-Sometimes from improved models being
adopted in one country, which another, through ignorance
or prejudice, will not follow; and perhaps, more fre.
quently, from the different nature of the soil. The spade
or the hoe must be light or heavy, broadcror more point-
ed, according as the soil is loose or stiff; for the heavier
or more tenacious the earth, the less quantity can be
raised at one stroke. But the most important of all im-
plements of husbandry is, doubtless, the plough : it has
been celebrated since the times of Moses and of Homer;
and it is the form of this instrument which has produced
the greatest contention among agriculturists. The plough
may be considered as a sort of pickaxe, drawn by animals
through the soil. In northern climates husbandunen are
great partisans of deep ploughing ; in southern countries
they are no less staunch advocates for light or more su-
perficial ploughing; and they are, perhaps, each equally
right in approving their own mode, and wrong in blaming
that of their opponents, for the different species of plough
are adapted to the soil of their respective countries.
In high latitudes, where there is much moisture and
but little heat, it is necessary to turn over the earth more
completely, in order to dry and pulverise it, especially
when of an argillaceous nature, which is very common
in northern countries. In more southern climes, where
heat and drought prevail, it is better to plough more light-
ly, the soil being frequently of a sandy nature, not reten-
tive of water.
ExIILY.—But supposing the soil to consist of two lay-
ors, the one of sand, the other of clay, the plough should,
I suppose, go deep enough to mix them together.
MRs. B.-No doubt their union produces as excellent
a soil as their separation makes a bad one. It signifies
not which is uppermost before ploughing; the more they
are mixed and incorporated together the better.
CARolixE.—But supposing there should be a good,
rich, vegetable soil on the surface, and the layers of
sterile ground beneath !
MRs. B.—Then a light plough should be used, and as
much care taken to prevent the mixture of the two, as to
13+
150 ACTION OF THE SOIL ON PLANTS.
effect it in the former case ; in short, attention must
always be paid to the nature and locality of the soil.
Ploughing must vary, also, according to the nature of the
produce to be raised. Lucern, which shoots out roots
four or five feet in length, requires deeper ploughing than
corn, whose roots are very superficial. Six or eight
inches is a sufficient depth for grain in general.
Extily.—When new land is first broken up, to bring it
under tillage, it will, I suppose, require deep ploughing to
pulverise the hard earth.
MRs. B.--That also depends on the nature of the soil.
In America, where fine rich vegetable soil is daily
brought into cultivation, nothing more is required than to
scratch the earth with a plough, and scatter the seed, in
order to produce an abundant harvest. But in England,
and all countries which have long been cultivated, the
good soil is already fully employed; and if any new land
is ploughed up, it is of a very inferior description, and it
is necessary not only to plough it deeply but repeatedly,
and to manure it, before it will yield a crop. The ope-
ration of bringing grass land into tillage is on the Conti.
nent frequently performed by a pickaxe with a double
prong, which breaks the earth more completely than the
plough.
Another point to be considered in tillage is the quan-
tity of manure to be spread upon the land. If this fall
short, and the ploughing has been deep, the nutritive par-
ticles may filter down lower than the roots can go in
search of them.
The more tenacious and compact the soil is, the closer
the furrows must be, and the narrower the ridges of earth
turned up, in order more effectually to pulverise it, and
afford channels for the water to run off. When the soil
is light, broader ridges and more distant furrows suffice :
it is even sometimes necessary to beat down the earth,
after having ploughed or dug it, in order to render it more
compact, especially in nurseries of young trees, whose
roots, in a loose soil, are liable to be torn up by the wind.
Deep furrows, or trenches, are very useful where the
ground is sloping, either to draw off or retain the water
ACTION OF THE SOIL ON PLANTS. 151
as required. If the soil be too moist, the furrows should
be made longitudinally, that is to say, from the top to the
bottom of the acclivity: they will then answer the purpose
of conduits to carry off the water. If, on the contrary,
the soil be dry, the furrows should be made transversely,
and the ridges of earth will act as parapet walls to retain
the water. ge
It is very necessary also, to pay attention to the period
of ploughing: it can be done neither in a wet season nor
during a hard frost, nor in very dry weather; but as you
have the whole season before you, from the reaping of
one harvest to the sowing for another, it is not difficult to
choose a period of appropriate weather, unless it be in
some strong clays, upon which a horse cannot be suf-
fered to tread during the winter. If the ground be in-
tended to lie fallow, the best use which can be made of
the repose allowed it, is to plough it in autumn, and
again in the spring; but if it is to be sown, the sooner it
is ploughed after harvest the better, in order to bury the
straw or other remains of the preceding crop, which will
enrich the soil, and also prevent the further growth of
weeds.
In hot countries the land cannot be ploughed in summer,
on account of its dryness; besides, it would afford the
means of evaporating the small remains of moisture of
the newly turned up earth, and that at a period, when it
has its most important functions to perform—those of soft-
ening and dissolving the hardest and most insoluble parti-
cles, which cannot be done unless the temperature of the
water be tepid.
CAROLINE.-But how can it be rendered tepid without
exposing it to the sun?—And in that case it will be eva-
porated.
MRs. B.-Exposure is not necessary ; the heat of the
atmosphere gradually penetrates the soil, and the water
diffused in it acquires the same elevation of temperature.
Farmers conceive that the soil is injured by the action of
ploughing in summer; but the injury proceeds from im-
peding the solutions requisite for the following crop. In
northern climates, where evaporation is less active,
ploughing is not so objectionable in summer.
I
r
2
ON THE IMPROVEMENT OF SOIL.
CONVERSATION XIII.
TIHE ACTION OF SOIL ON PLANT'S CONTINUED.—ON
THE IMPROVEMENT OF SOIL.
MRs. B.-We may now proceed to examine the vari-
ous modes of improving the soil by mineralogical pro-
cesses. The first and most simple of these is to clear it
of stones; when stones are injurious to cultivation.
CARoline.—But are not stones always injurious ! For
of whatever materials they may be composed, they are
such hard insoluble bodies that vegetables can acquire
no nourishment from them.
Mrs. B.—True; but stones often perform a very use-
ful mechanical part in agriculture. They render a clay
soil less tenacious by separating its parts, and thus leave
room for water to drain off: they form, as it were, so
many natural irregular conduits; and if you take them
away, you must employ them for the construction of arti-
ficial conduits to effect the same purpose.
CAROLINE.-This may be the case with stones buried
in the earth, but those lying on its surface must surely be
prejudicial to vegetation ?
MRs. B.-Generally they are so, but not universally :
in some hot countries grass cannot grow, excepting under
shelter of loose flat stones. . I have seen pastures of this
description on the plains of Crace, near Arles. They
exhibit the singular spectacle of flocks of sheep feeding
on dry stones, as the grass which grows beneath them is
not visible; but the sheep find a tender, if not abundant
pasture, by turning up these stones, or nibbling beneath
them; while the pebbles, thus overturned, afford shelter
to the adjacent blades which are just sprouting, and would
be burnt up without such protection.
In some instances the ground in which fruit-trees are
planted, has been paved with stones, in order to retain
the moisture beneath by preventing evaporetion.
In cold countries stones are sometimes considered ad-
ON THE IMPROVEMENT OF SOIL. 153
vantageous as communicators of heat, those of a dark
colour especially. They act on the surface of the earth
both as reflectors and radiators of heat; and are fre-
quently placed round the stems of plants in a vineyard,
in order to give them additional heat. It must be allowed,
however, that those occasional uses to which stones are
applied in husbandry, are to be considered rather as ex-
ceptions to the general rule, and that stones may be
looked upon in most cases as either useless or pernicious.
The improvement of soil by the admixture of foreign
ingredients, amendement, is one of the most important
operations of agriculture.
If the soil be too stiff from excess of clay, it will be
improved by sand; and if too loose from excess of sand,
it will be improved by clay : but when sand is mixed with
argillaceous soil, the latter must be broken and pulverised,
which may be effected by exposing it to the frost, and af.
terwards drying it. Marl is a natural compound earth,
used with great success in the melioration of soils: it
consists of a mixture of clay and calcareous earth or
lime in various proportions.
Argillaceous marl, which contains more clay than lime,
is advantageous for a dry sandy soil; while calcareous
marl, in which the lime predominates, is suited to an ar-
gillaceous soil. The great advantage of marl is, that it
dilates, cracks, and is reduced to powder by exposure to
moisture and air. Marl in masses would be totally use.
less on the ground; yet it is necessary to begin by laying
it on the ground in heaps, for the more it is heaped the
more it dilates, splits, and crumbles to dust; in which
state it is fit to spread upon the ground.
Marl is sometimes intermixed with other earths; some-
times formed into a compost with manure before it is
laid on the soil: it should be applied sparingly at a time,
and renewed frequently. Its advantages are manifest;
it subdivides the soil and accelerates decomposition, its
calcareous particles disorganising all animal or vegetable
bodies, by resolving them into those simple elements in
which state they combine with oxygen; it facilitates this
union : hence, though not itself of a nutritious nature, it
romotes the nourishment of plants by preparing their food,
The best period for marling ground is the autumn,
154 ON THE IMPROVEMENT OF SOIL,
Lime is also an excellent amendement. It is procured
from limestone by exposing it to the heat of the kiln,
which evaporates the water and carbonic acid with which
lime is always found combined in nature, and renders it
quick as it is commonly called; that is to say, of a caus-
tic burning nature, having such an avidity for water and
carbonic acid, from which it has been forcibly separated,
that it seizes upon these bodies, wherever they are to be
met with, and disorganises the compounds in which they
are contained in order to combine with them.
ExILY.—But since lime is of so destructive a nature,
I should have thought that it would have been necessary
to add, instead of subtracting, water and carbonic acid,
in order to soften its caustic properties, which seem cal-
culated rather to destroy than promote vegetation.
MRs. B.-Were quick-lime applied immediately to
plants, it is true that it would prove a poison to thern ;
but, when spread upon the earth, it rapidly attracts water
and carbonic acid from the atmosphere, and it is only
when thus modified that it promotes vegetation.
ExIILY.—Then why force from it, in the kiln, thoso
very ingredients which must be restored to it so soon af.
terwards 2
MRs. B.-In its natural state of limestone, it is of too
hard and compact a nature to be diffused in the soil : and
even quick-lime would be too solid, were it not, that
through its combination with water and carbonic acid
from the atmosphere, it splits and crumbles to powder.
I believe the experiment of pounding and grinding
limestone to powder, was tried in Scotland, in order to
save the expense of burning it in o quick-lime, but not
found to be efficacious like the powder of slacked lime.
Lime is particularly adapted to poor cold soils, such as
those of marshes, which have not energy to dissolve or-
ganic bodies. The quantity to be used must be propor-
tioned to the manure which is laid upon the ground; for
the more organic matter there is to be dissolved, the
greater will be the quantity of lime required for that pur-
ose. To mix lime with peat-earth, is said to have an
immediate and most beneficial effect, and that many bogs,
ON TIIE IMPROVEMENT OF SOIL. 155
having been previously drained, have been converted
into fertile land.
The lime procured from fossil-shells is highly esteemed
by agriculturalists: its pre-eminence results, probably,
from its retaining some vestiges of organic remains of
the animals who once inhabited these receptacles.
CARoline.—The shells of living animals must then be
still more valuable for this purpose 1
MRs. B.-They are neither so readily, or so abun-
dantly obtained; large strata of fossil-shells are to be
ſound in some soils, while of living shells you could pro-
cure at most, the refuse of the fish-market.
Ashes are very beneficial to the soil : they differ much
in their composition, according to the nature of the body
from the combustion of which they result, but their gene-
ral ingredients are potash, silex, and calcareous earth.
They attract moisture from the atmosphere, and thus ac-
celerate vegetation.
Sulphate of lime, commonly called gypsum, is an ex-
cellent amendement; but chemists are not agreed as to the
manner in which it acts on vegetation. It is strewed
over crops when the leaves are in full vigour, towards
the latter end of April or the beginning of May, and it
should not be laid on more than once in the year. Clo-
ver and saintfoin contain gypsum in their stems to a con-
siderable amount; and when soils are said to be tired of
those plants, it is probable that they are no longer able to
supply this necessary ingredient. It is on those crops
that gypsum is found to be most efficacious.
Iſaving now made you acquainted with the various
modes of improving the soil, we are next to consider
which are the best means of supplying plants with food.
CAROLINE.-All natural soils, with the exception, per-
haps, of burning sands, or arid rocks, must contain nour.
ishment for plants; otherwise they would not grow spon-
taneously as they do in wild, uncultivated countries,
which often abound with forests and rich pastures.
MRs. B.-True; but though this supply be sufficient
for a natural state of vegetation, when the land is forced,
as it were, by agriculture to yield food for man, a greater
156 ON THE IMPROVEMENT OF SOIL
produce must be obtained; and we cannot raise those
rich and numerous crops, so necessary to the existence
of a civilised country, without affording the vegetable
creation an artificial supply of nourishment: for it is an
axiom, no less true in the vegetable than in the animal
kingdom, that food must be proportioned to the popula-
tion, in order to maintain it. The mode which art has
devised to increase the quantity of food for plants is to
spread manure on the soil. Manure consists of the re-
mains of organised bodies of every description, whether
animal or vegetable, in a state of decomposition; that is
to say, resolving itself into those primitive elements which
can re-enter into the vegetable system.
CAROLINE.-The preparation of food for plants is then
precisely the inverse of that for animals, or at least for
animals of the human species. Our culinary art consists
in mixing and combining together a variety of ingredients
to gratify the palate; while bodies must be decomposed
and resolved into their simplest elements, to suit the
vegetable taste.—And how is this process performed !
MRs. B.-I have explained it to you in our Conversa.
tions on Chemistry: it is by the last stage of fermentation
—putrefaction. Loathsonie as this term may appear to
you, yet, when you consider it as the means which
Nature employs to renovate existence, and continue the
circle of creation, you will view it with admiration rather
than with disgust.
EMILY.-It is very true ; the operations of Nature,
when philosophically contemplated, are always admira-
ble: those elementary substances, which in their simple
state would be disagreeable to us, by passing into the
vegetable system, are converted into the most palatable
and nutritious food. When in the resources of Nature
we discover such evident proofs of the goodness of the
Creator, the philosopher may well exclaim with the poet :-
&G o
jºº" sº
Thus wondrous fair; thyself how wondrous then :
Unspeakable ! who sit'st above these heavens
To us invisible, or dimly seen
In these thy lowest works; yet these declare
Thy goodness beyond thought, and power divine.'
ON THE IMPROVEMENT OF SOIL. 157
MRs. B.-This beautiful burst of praise, into which
Adam breaks out on the creation at large, is no less
applicable to the wisdom and prudence displayed in the
arrangement and distribution of its minutest parts.
The principal result of the decomposition, whether of
animal or vegetable matter, is carbonic acid; and in this
state carbon, which we have called the daily bread of
plants, finds entrance at their roots.
CARoline.—But it is not enough to introduce carbonic
acid at one extremity of the plant; you must get rid of
the oxygen at the other extremity, before the plant can
feed upon its daily bread.
ExIILY.—This, you may recollect, is performed by the
leaves when exposed to light and air.
MRs. B.-Manure acts on dry soils also as amendement
by retaining moisture. Manure which has not completely
undergone the process of fermentation, so that the straw
is not yet wholly decomposed, is best adapted to strong
compact soils: the tubular remnants of straw answer the
purpose of so many little props to support the earth, and
afford a passage for the air, thus rendering the soil lighter;
besides, the completion of the ferinentation taking place
after the manure is buried in the soil, has the advantage
of raising its temperature.
EMILY.—Since the putrid fermentation reduces every
animal and vegetable substance into its primitive elements,
there are none, I suppose, which may not be converted
into manure.
MRs. B.-None; but some bodies are more readily
decomposed than others: it is from domestic animals
that the best manure is obtained. In maritime districts,
fish, when sufficiently abundant, are sometimes used to
manure the land. They are easily decomposed, and
afford a considerable quantity of nourishment. Even
such hard substances as horn, hair, feathers, and bones,
are all resolvable into their primitive elements, and make
excellent manure; but, owing to their dry nature, require
a longer period for their decomposition. Such substances
are calculated, not for annual harvests, but to fructify the
14
158 ON THE IMPROVEMENT OF SOIL.
soil for a produce of much longer duraton, such as that
of olive-trees and of vineyards.
Vegetable manure does not always undergo fermenta-
tion previous to being buried in the soil: green crops,
such as lupins and buck-wheat, are sometimes ploughed
in, and thus buried for the sole purpose of enriching the
soil. A green crop contains a considerable quantity of
water; and the plants, when buried, serve to lighten the
soil previous to decomposition, and subsequently to enrich
it with food for the following crop. This species of
living manure is particularly calculated for hot countries,
on account of the abundance of moisture it incorporates
with the soil.
ExILY.—I have seen sea-weeds used as manure, which
has at least the advantage of being a gratuitous crop.
MRs. B.—Gratuitous in some respects, but requiring a
difficult and laborious carriage. The Isle of Thanet owes
its reputation in a great measure to the power of procu-
ring this manure. And the sea-salt they contain is also
favourable to vegetation. Straw is an excellent ingredient
for manure; but it requires being mixed with animal
manure, or stratified with earthy matter. Bark and saw-
dust are occasionally used for manure : they should,
however, with greater propriety, be considered as mate-
rials for improving the soil ; as they afford but little
nourishment.
The grain which produces oil, such as linseed, rape-
seed, &c., makes excellent manure after the oil has been
expressed : in this state it is called oil-cake, and its
unctuous qualities serve to accelerate decomposition;
but in England it sells at such a price, as to make it a
doubtful speculation even to feed cattle with. It would
be too expensive to be used as manure.
EMILY.—Pray, would not soot make very good manure’
It is almost pure carbon, in so higly a pulverised state
as must render it fit to enter into the vegetable system.
MRs. B.-You forget that it is first necessary to combine
it with oxygen; and this is a work of time. Soot has
however an immediate beneficial effect, though not a
very permanent one : it is used in large quantities in
ON THE IMPROVEMENT OF SOII,. 1.59
IIertfordshire, both for grain and pasture, and is strewed
on the land in March and April, for the crop of the same
year.
CARoll NE.-I recollect having observed that the envi.
rons of the spots where charcoal has been prepared in
the mountains, are absolutely destitute of vegetation,
although strewed with charcoal powder.
Mrs B.-But were you to visit these same spots some
few years afterwards, you would find vegetation more
flourishing, more vigorous, and especially greener, than
elsewhere, because the charcoal-powder will have gra-
dually combined with the oxygen of the atmosphere, and
thus vegetation be luxuriously supplied with its favourite
food, carbonic acid.
The most common manure consists of a mixture of
animal and vegetable materials; and this again is fre-
quently stratified with mineral substances, such as mud
from the streets, dust from the roads, or earth of different
descriptions, the whole forming a rich compost. Mud
from the beds of rivers, when it can be obtained, is a very
valuable ingredient for such a compound, as it abounds
with organic remains of fish, shells, reptiles, and rotten
plants. Often, however, before being laid upon land, it
requires being well turned up and exposed to the air for
SOIme t1nne,
CARolisE.—It is to be regretted that such precious
relics should, in general, be lost by being carried by the
current of the river into the sea; but the slime of ponds
and all stagnant waters must make very rich manure.

Mrs. B.-Yes; they may be considered as store-
houses of materials, ready to return into the vegetable
system.
The elevation of temperature produced by the comple-
tion of fermentation of the manure, after it is mixed with
the soil, is but inconsiderable, excepting in garden culture,
where, accumulated in hot-beds, it often produces a tem-
perature equal to that kept up in a hot-house.
Short manure, that is to say, that which is thoroughly
decomposed, and in which the water and other evapora-
ble parts have in a great measure disappeared, contains a
considerable quantity of carbon.
160 ON THE IMPROVEMENT OF SOIL.
Long manure, in which state fermentation is but little
advanced, contains a greater proportion of water : the
first is, therefore, best adapted to moist, the latter, to dry
soils.
EMILY.—But if the fermentation be completed previous
to mixing the manure with the soil, are there not many
volatile products which escape into the atmosphere, and
which might, if buried in the earth, have promoted vege-
tation?
Mrs. B.—No doubt. It is incalculable how many
valuable materials are “wasted on the desert air” which
should have given vigour to vegetation; others are dis-
solved by moisture, and drained off by rain; but these
liquefactions are generally collected and turned to ac-
count. To prevent, as far as possible, such losses, dung-
hills should be sheltered from the atmosphere by sheds:
these should, however, remain open on the sides, as air
in a moderate quantity is required te promote fermenta-
tion.
EMILY.—In which state do you consider it most ad-
vantageous to bury manure in the soil: when the fer-
mentation is only partially, or when it is completely
effected 1
CAROLINE.-I should suppose in the former state, in
order to prevent the loss by evaporation. When the
fermentation goes on in the soil, the elastic as well as the
liquid and solid parts are retained ; then the act of fer-
mentation raises the temperature.
MRs. B.-One state is better for some species of
crops, and the opposite for others. The only disadvan-
tage attached to long manure is, that it requires a greaten
length of time to convert it into nourishment for plants.
Short manure is a meal already cooked, and ready for
the crop to feed on ; if, therefore, the crop requires very
prompt sustenance, the former must be used; if not, the
latter is in every respect preferable : it is particularly
adopted to stiff soils, the straw previous to its decomposi-
tion, rendering it lighter.
EMILY.-It is evident that it must be advantageous to
bury either description of manure as soon as it is spread
ON ROTATION OF CROPS. 161
on the soil, to prevent loss by evaporation; but how deep
should it be laid in the soil 7
MRs. B.-That depends upon the nature of the cul-
ture ; for the manure should be as much as possible
within reach of the roots. For this purpose, it should
not be buried quite so deep as the extremity of the roots;
for, in proportion as it is dissolved and liquified, it will
naturally descend. Due allowance must be made for
this; for, if any part subside below the roots of the plants,
it is utterly lost, at least for that crop.
ExILY.-It is then, I suppose, better to manure the
land in the spring than in autumn, lest the winter-rains
should dissolve it too much, and endanger its sinking
below the roots of the crop.
Mrs. B.--That is the prevailing opinion of agricul-
turists. With regard to the quantity of manure, it is a
commodity so scarce, that it is not likely to be employed
in excess. This occurs, however, sometimes in garden
culture, and it produces a strong and disagreeable flavour
in the vegetables; even the cows avoid the strong, coarse
grass which grows on spots they have manured too abun-
dantly. But the stock of manure is generally so limited,
that it has been the study of agriculturists to discover
some means of compensation for a deficiency, rather than
to apprehend danger from excess. This compensation
has been found in a judicious system of crops; but it is
too late to enter upon a new subject to-day, and one of
so extensive a nature well deserves to have a morning
dedicated to its consideration.
CONVERSATION XIV.
THE ACTION OF SOIL ON PLANT'S CONTINUED,-
ROTATION OF CROPS.
Mrs. B.-It has long been observed, that two successive
harvests of the same species of plants, or even of plants
14*
162 UN ROTATION OF CROPS.
of the same family do not succeed: the second appears
to degenerate, as if the first had been injurious to it.
CARolf NE.-The first crop had no doubt exhausted the
soil of nutriment.
Mrs. B.-In the infancy of agriculture, when land was
plentiful, because inhabitants were scarce, this was easily
remedied by cultivating only a certain portion of land,
and, after having exhausted it, transferring the cultivation
to another part, and thus successively bringing new land
into tillage, till, after a series of years, they return.to the
spot which had been previously cultivated. This mode,
called ecobuage, was first introducd by the Celts, and
may still be traced among some of their descendants in
Brittany. They usually commenced their operations by
burning the natural product of the soil before they plough-
ed it. If the soil was stiff and argillaceous, the ashes re-
sulting from this combustion seemed to meliorate it, by
increasing the stock of carbon, of sand, and of salts; but
if light, such a proceeding was not judicious.
The system of fallows, which we derive from the Ro-
mans, is an improvement on that of the Celts; the soil is
allowed only one year's repose occasionally, and during
that season it is repeatedly turned over by the plough ;
every part is thus exposed to the atmosphere, whence it
absorbs oxygen, and the weeds, being buried by the
plough, serve to enrich, instead of exhausting, the land.
The system of assolemens we owe to those excellent
farmers the Belgians. It is of two descriptions: the first
consists in the judicious cultivation of such a succession
of crops, that they shall derive benefit instead of injury
from each other; the second is that of raising two crops
simultaneously, which shall mutually benefit each other.
As we have no precise term to express these processes, I
shall take the liberty of using the French word assolement.
Those of the first description, which our farmers de-
nominate a rotation or course of cropping, is particularly
adapted to northern climates.
EMILY-And of what description are the crops which
ought to be cultivated in rotation?
MRS. B.-Before this point can be determined, we
ON ROTATION OF CROPS. 163
must endeavour to solve the problem why one crop is
prejudicial to another of the same family; why two sorts
of grain cannot be raised in succession without the latter
degenerating; while leguminous plants succeeding a crop
of grain are improved by it.
EMILY.—I thought that the first crop, especially if one
of grain, which requires so much nourishment, would in-
jure the soil for any succeeding crop by exhausting it of
nutritive particles.
CARoline.—But since it appears that leguminous plants
can follow grain with advantage, it seems evident that
these two crops must feed upon different kinds of nourish-
ment, and thus the one will not interfere with the other.
Exºrily.—You forget, Caroline, that plants cannot select
their food, but suck up whatever comes within reach of
their roots, and is sufficiently minute to find entrance
there. All plants must, therefore, feed upom the same
nutritive particles.
CAROLINE.-Then I will suggest another explanation,
Perhaps the roots of plants which succeed each other
without injury may be of different lengths, and one crop
seek its nourishment near the surface, while the other
penetrates deeper into the soil; thus they would both be
fed without interfering with each other.
EMILY.—But you do not consider, Caroline, that the
plough overturns your theory, in overturning the soil;
for it brings the lower part to the surface, and mixes the
whole so well together that the nutritive particles must
be pretty equally diffused throughout.
MRs. B.-Your observation is very just; and we find
that clover, which has very superficial roots, will not
thrive after lucern, whose roots are very long. This
theory, however, is applicable to simultaneous crops
whose roots are of different lengths. Another theory has
been suggested, which is, that the fall of the leaf of the
first crop fertilises the earth for a second : this is un-
doubtedly true to a certain extent; but the foliage can
fertilize the earth only by being converted into manure,
which would equally afford nourishment for a second
crop of the same nature.
I (34 ON ROT.ATION OF CROPS.
CARolling.—Nay; one would even suppose that a
green crop, ploughed into the soil, would afford more
appropriate food for a second crop of the same descrip-
tion than for one of a different family; that the leaves of
straw would yield the best nutriment for a future crop of
corn, and of grass for that of grasses; while the fact,
you say, is exactly the reverse.
MRs. B.-The theory which M. De Candolle is most
inclined to favour, if indeed he is not its author, is the
following. A plant, being under the necessity of absorb-
ing whatever presents itself to its roots, necessarily sucks
up some particles which are not adapted to its nourish-
ment, and in consequence,—after having elaborated the
sap in its leaves, and re-conducted it downwards through
all its organs, each of which takes in the nourishment it
requires; after having extracted from it the various pe-
culiar juices, and, in a word, turned it in every possible
way to account,-finds itself encumbered with a certain
residue, consisting of the particles it had unavoidably ab-
sorbed, and which were not adapted to its nourishment:
these particles, having passed through the system without
alteration, are exuded by the roots which had absorbed
them, and thus return into the soil, which they deterio-
rate for a following crop of the same species of plant, but
improve and fructify for one of another family; thus
affording an admirable proof of the wise economy of Na-
ture, in multiplying her vegetable produce by feeding
different plants with different substances, and enabling
beings, incapable of distinguishing or selecting their food,
to obtain that which is appropriate to them.
EMILY.—It is, indeed, admirable ! Then, though the
roots of plants can make no choice, their organs are in
some measure capable of selecting, since they reject, and
will not elaborate, substances which are not adapted to
the nourishment of the plant.
MRs. B.—If we cannot exactly allow them the nice
discrimination of the chemist, we must at least suppose
their laboratory to be so arranged as to act only on
bodies congenial to the plant.
CARol.INE.-And the rejected substances, which would
ON ROTATION OF CROPS. 16J
be poison to one family of plants, when transfused into
the soil, is greedily devoured by a succeeding crop of a
different family.
EMILY.—Yet Mrs. B., there is land in the Vale of
Glastonbury, in Somersetshire, which is celebrated for
growing wheat for many years together without any ma-
nure ; and I have heard that in the neighbourhood of the
Carron iron-works, in Scotland, wheat has been raised
above ity years, without injury either to the crops or
the soil.
Mrs. B.-Those soils must not only abound with vege.
table nourishment, but the land be particularly well
adapted to growing wheat; consequently, the roots would
have little or nothing to exude, and successive crops of
wheat might be raised so long as the land was not ex-
hausted. This explanation would reconcile your diffi-
culty to the theory of exudations; but, interesting and
plausible as this theory is, it requires the confirmation of
facts to rest on a solid foundation: few experiments have
yet been made relative to it. Mr. Brookman has raised
some plants in sand, and ascertained that they exuded by
the roots small drops during the night, which there is
reason to suppose was the object in research ; but ex-
periment has not yet been pushed far enough fully to
verify it.
CARol.INE.-It appears to me to explain the theory of
assolement so well, Mrs. B., that I feel strongly inclined
to put my faith in it. How perfectly it accounts for the
advantages derived from cultivating leguminous and
graminerous crops in succession, the exudations of the
one being exactly the nutriment which the other requires.
MRs. B.-I am so much inclined to agree with you in
opinion, that I shall venture to draw conclusions from it,
as if the theory were established ; cautioning you, how-
ever, to bear in mind, that until it has been further inves-
tigated, it must be considered as little more than hypo-
thetical.
You must besides remember that it is manure which
affords the grand store of provisions equally good for
plants of every description. If, in addition to the exu.
166 ON ROTATION OF CIROPS.
dations of leguminous plants, you plough in the crop itself,
the succeeding crop of corn will be considerably im-
proved.
EMILY.—Supposing you were to plough in a crop of
young rye, could you not the following year sow wheat
with advantage 7 for the rye would have had but little
time to deteriorate the soil by its exudations, and afford
much manure by the fermentation of its own substance.
MRs. B.-I do not know that the trial has ever been
made ; but it would certainly succeed better than if you
were to reap the rye when ripe, and afterward sow wheat:
for, in this case, the rye would have given to the soil the
whole of its exudation, and little or none of its own sub-
Stan Ce,
CARoline.—May it not be objected to this theory that
Nature does not raise plants of different families in suc-
cession ? The seeds of the parent-plant fall to the ground
annually, and produce other individuals of the same spe-
cies, and on the same spot, for centuries; and yet that
spot must be vitiated for such plants by the long series of
exudations of their progenitors.
MRs. B.-If Nature does not usually employ succes.
sive, she does simultaneous assvlements. In her sponta-
neous forests she raises such a prodigious variety of trees
and shrubs, and in her meadows such a multiplicity of
herbs and grasses, that the different plants mutually sup-
ply each other with exudations.
EMILY.-Besides, where Nature acts without restraint,
she enriches the soil not only by the annual fall of the
leaf, but, in the course of time, the whole plant, whether
grass, shrub, or tree, returns to the soil, to repay the
nourishment it had received during its life.
MRs. B.-The soil can never be impoverished by na-
tural vegetation: that of forests, where man does not cut
down and carry away the trees, is not more exhausted of
nutriment at the present day than it was a thousand years
ago.
Those magnificent forests which covered the face of the
greater part of Ameri a, when it was first known to us,
never had any other manure than the remains which its
ON ROTATION OF CROPS. 167
vegetable and animal productions afforded; nor can a
better be supplied. And we in some respects copy Na-
ture when we prepare the soil for corn by ploughing in a
green crop of leguminous plants.
There is nothing which exhausts either a plant or the
soil in which it grows, so much as the ripening of its seeds,
No animal labours with greater effort to support its off.
spring than the poor plant to bring its seeds to muturity:
it pumps up sap with all its powers of suction; yet, if it
has much seed to ripen, after having accomplished its
task, it frequently perishes through exhaustion from the
intensity of its efforts.
Perennial plants have but few, and but small grains to
ripen, while those of annuals, are large and much more
abundant; and it is this difference, perhaps, which con-
stitutes the real distinction between these two classes of
plants: the one, exhausted by its efforts, dies after ri.
pening its seed; while the other, having a less laborious
task to perform, lives through several successive years.
CARolin E.-If that is the only distinction, an annual
Inight live several years, were its seeds prevented ri.
pening.
Instances of this sometimes occur in cold countries,
such as Scotland. If the season has not afforded suffi.
cient heat to ripen the corn, and that the following winter
has not been so severe as to prove fatal to it, it will ripen
the succeeding summer; and, indeed, whenever by any
artificial means you prevent the ripening of the seed of
an annual, it becomes perennial.
But to return to our subject. The succession of crops
should be so arranged as to prevent as much as possible
the growth of weeds: but what plant is it which deserves
so opprobrious a title 1 for not one issues from the hands
of its Creator which is not destined to act some useful
part in its own sphere : either its exhalations purify the
air; its exudations fructify the earth; its fruit supplies us
with food or clothing; its blossoms regale our senses;
and even its poisons minister to our diseases. What
plant can we then denominate a weed ?—The only blame
which attaches to weeds is (as Dr. Johnson expresses it)
168 ON ROTATION OF CROPS.
being out of their place; and it is the business of the
agriculturist so to fill up the place they would occupy, as
to drive them out of the field. This cannot be more ef.
fectually accomplished than by the cultivation of artificial
grasses, such as clover and lucern, which, when sown
thick, produce a shade very prejudicial to the growth of
weeds; if sown thin, so as to leave space, light, and air,
it, on the contrary, encourages their growth.
There is nothing more favourable to the improvement
of land than hoed crops, provided no immediate profit be
expected from them, and that we are satisfied if they re-
pay the expenses of cultivation; that is to say, the value
of the seed, the hoeing, the ploughing, and the manure.
EMILY.—But why are not these crops sown so thick as
to prevent the growth of weeds, and, consequently, the
necessity of hoeing 1
MRs. B.-These crops consist of plants whose roots
require a great deal of nourishment, such as peas, beans,
turnips, potatoes, and carrots; and, if sown thick, the
soil would not afford a sufficient supply.
ExILY.—Yet the 'weeds which spring up between
these plants must rob the soil of a part of its nourish.
Iment.
Mrs. B.-They do so, but only temporarily; for the
dead weeds, after hoeing, return to the soil in the form
of manure. . The advantage of hoeing is not confined to
the destruction of weeds: it loosens the earth so as to
admit the air, turns it over, and heaps it around the roots
of the plants cultivated.
As hoed crops stand in need of a great deal of ma-
nure, they should precede grain, which also requires
manure' to ripen the seed; and it is from the sale of
grain, raised under these advantageous circumstances,
that the cultivator will derive his profit.
It must be recollected, also, that the more the green
crops are increased, the greater is the number of cattle
you are enabled to feed, and, therefore, the more consi-
derable is the stock of manure. It is very remarkable,
and, however paradoxical it may appear, is nevertheless
true; that, since the introduction of assalements, meadows
ON ROTATION OF CROPS. 169
diminish while cattle increase, and corn-fields diminish
while grain increases. These miracles are performed
by the artificial grasses, and the leguminous and other
green crops, which not only prepare the earth for grain
by their exudations, but enrich it by their remains ; which
leave no space for weeds, and supply abundant food for
cattle.
CARo1.1NE.—And what is reckoned to be the due pro-
ortion of corn to meadow land in a farm 7
MRS. B.-The distribution of a farm should be so ar-
ranged that the several portions should mutually contri-
bute to each other's advantage. The farmer should aim
at raising every year the same quantity of produce ; for
though it is true that the vicissitudes of seasons render
this end unattainable, yet, by keeping it in view, you will
the more nearly approximate to it.
When once the land is laid out to feed the number of
cattle required for the work of the farm, and to produce
the manure necessary for the soil, no change can take
place without disadvantage. If you augment the produce
of grain, it must be at the expense of the leguminous
crops : the cattle will suffer for want of forage, and the
soil from deficiency of manure.
EMILY.—And even the corn the following year will
degenerate for want of that preparation of the soil pro-
duced by leguminous crops.
MRs. B.-The Belgians, whom we consider as among
the best farmers, lay out their land so as to obtain, as far
as possible, equal results annually. They derive their
profit from the sale of their corn: this alone goes to mar-
ket, the forage being all consumed by the farming cattle,
and the manure employed on the soil. A Belgic farm
consists generally from thirty to forty acres: the succes-
sion of crops is strictly regular, and comprehends a pe.
riod extending from ten to fifteen years.
In rural economy an intervening crop is occasionally
raised between two regular crops; thus, buck-wheat is
often sown in that country as soon as the land can be
ploughed after wheat, and is gathered in late in the au-
tumn; but a double crop of grain is very exhausting to
5
170 ON ROTATION OF CROPS,
the soil, and it would be better that these stolen interme-
diate crops should be of leguminous plants. In England
we do not attempt them : our corn is got in too late to ad-
mit of sowing for a second produce the same season.
EMILY.—What a prodigious advantage a rotation of
crops has over fallows ' ' If leguminous crops do not
yield any profit, they defray at least all the expenses of
their cultivation, and prepare the soil for a rich harvest
of grain; while a fallow affords no crop whatever to re-
pay the expense of ploughing and manuring, and does
not so well prepare the soil for grain.
MRs. B.--The greater the variety of crops raised in à
country, the more we consider that country as advanced
in the knowledge of agriculture, for every new plant af.
fords security against sterility; and the more crops are
diversified, the smaller are the chances of suffering from
the inclemencies of the season, for what is injurious to
the one may be salubrious, or at least not detrimental, to
the others. It affords also a surer market; for every spe-
cics of produce will not fall in price at the same time, and
thus the chances of loss are diminished. It is also an
essential point, so to distribute the labour of a farm, that
cvery operation may be made at the most suitable period.
ExiILY.—The course of cropping must admit of modi-
fication, according to the locality, or the greater demand,
for any one species of produce.
Mrs. B.-Certainly ; in England, for instance, where
the beverage of the common people is beer, a greater
quantity of barley and hops must be raised than in wine
countries. Then the moisture of the English climate
admits of our raising very abundant crops of turnips,
peas, and beans: these plants enter with great advantage
into our course of crops.
CARol.INE.-The vicinity of great towns must also in-
fluence the nature of the crops; it will be necessary to
supply their markets not only with food, but also with
bulky produce, the carriage of which is expensive; such.
for instance, as hay, a very great quantity of which is re-
uired to maintain the stock of horses and milch cows of
à large town, which are quite independent of a farm.
*"
ON ROTATION OF CROPS. | 7 |
MRs. B.--So far as regards their labouring for a farm,
it is true; but the land profits by their manure : it is in
order to supply hay for these animals that you generally
see large towns surrounded by grass land. The oxen
and sheep destined for food are brought from more distant
parts, as they carry hemselves to market almost free of
expense.
The culture of the vine, especially in temperate climates
where this plant requires a great quantity of manure,
necessarily modifies the assolement; for the farm must be
so distributed, as not only to afford manure for the suc-
cession of crops, but a large surplus for the vineyard.
EMILY.—This must be difficult to accomplish without
making the general culture suffer from such a considerable
subtraction; and indeed I have observed, that in Switzer-
land, every thing seems to be sacrificed to the culture of
the vineyard, as being that portion of the farm which
affords the greatest profits.
MRs. B.-And which also occasionally produces the
greatest losses. It may be considered as a game in which
the highest stake is pledged ; the greatest pains are
therefore taken to increase the chances of winning.
The nature of the soil must also modify assolements.
The light soils of Belgium and Alsace are very favourable
to this system, while stiff tenacious soils offer considerable
difficulties: they are, however, well worth the trouble of
surmounting, as this mode of culture diminishes the quan-
tity of manual labour which such ungrateful soils require;
and which renders their cultivation so expensive.
ExILY.-And what is the most eligible succession of
crops?
MRs. B.-The most common is an assolement of only
four years; the first of which is a hoed crop, to destroy
weeds: turnips, potatoes, beet-root, carrots, or any other
plants with long roots, are very appropriate for this pur-
pose ; as it obliges the farmer to plough deep, in order to
prepare the soil for them. After gathering in this crop,
the leaves and remnants of the plants are ploughed into
the soil, the land is manured, and wheat and clover are
sown together.
| 72 ON ROTATION OF CROPS.
The clover does not make its appearance till after the
corn is reaped. Little advantage is made of the produce
of clover the first season, but the following year it yields
an abundant harvest. After having mowed it, the ground
is ploughed, and the remains of the clover buried; and
thus, both by its exudations, and by a part of its own sub-
stance, it renova,es the soil after the exhaustion it had
undergone in ripening the corn, and enables it to produce
a second crop of grain the fourth year, which completes
the assolement.
The rotation of crops must, however, necessarily vary
with the soil : that which I have described, from M. Dé
Candolle, is probably best adapted to France; in England
turnips, I believe, are usually followed by barley, clover,
and wheat.
CARolix E.-Pray, why should not trees require an
assolement as well as corn and leguminous plants 7 for the
exudations of a tree during the number of years it lives,
must greatly injure the soil for another of the same kind.
—Nay, I wonder how the same individual tree can thrive
throughout a long life in a soil so deteriorated.
MRs. B.-You must consider, in the first place, that the
roots of a young tree are of small extent, and both seek
their food, and give out their exudations, in the ground
immediately surrounding the stem. In proportion as they
lengthen, they extend their researches, spreading wider
and piercing deeper into the soil; thus, afer having
exhausted it of nourishment, and deteriorated it near the
stem, they find fresh aliment in a more enlarged sphere.
EMILY.—Then when a tree dies, if another of the same
kind be planted in its place, the young roots will find the
soil near the stem exhausted of nutritive particles, and
vitiated by exudations: and yet, when a dead tree in an
avenue is replaced by another of the same species, it
grows without difficulty.
MRs. B.-If you replaced it by one of another family,
there is no doubt but that it would thrive better. One of
the same species is, however, not without resources; for
you must consider that the soil nearest the stem of the old
dead tree has not been acted upon by the roots for a num-
ON ROTATION OF CROPS. 173
ber of years; and, during this period of repose, it has
been able, in a great measure, both to renovate its nutri-
five particles by the natural manure it receives annually
from the fall of the leaf, and to purify itself from exudations
of the old tree; these being absorbed by the grasses,
underwood, and plants of various descriptions which
surround the tree, and which in return supply the soil
with exudations adapted to forest trees: these ameliora-
tions will enable a second tree to live and grow upon the
same spot as its progenitor, though certainly not with the
same vigour as if it were of a different family.
CARoline.-In replacing a tree in an avenue, we are
not at liberty to choose its species; but in our gardens it
is surely wrong to replace an old fruit-tree by another of
the same species.
Mrs. B.-This is not so easily obviated as you ima-
gine; for it is not sufficient to change the species: you
must change the family; and almost all our fruit-trees
are of the same family. To remedy this inconvenience,
the gardener must supply the young tree with fresh soil,
which in a great measure answers the same purpose.
This new earth should, if possible, be brought from the
neighbourhood of forest-trees, which are of another fa-
mily. Manure may at the same time be introduced,
Nursery gardeners alternate plantations of fruit and of
forest-trees.
CAROLINE.-When a wood is cut down another springs
up of the same trees, shooting up from the old roots, or
germinating from the seeds naturally sown. Yet how
can these young plants find sustenance in a soil both ex-
hausted and vitiated by the parent-trees?
MRs. B.-You assume as a fact what is only a natural
inference. If, when a natural forest be cut down, a
second springs up, it will consist of trees of another fa-
mily; a forest of oaks, for instance, may be succeeded
by one of aspen, which is of a different family, or the
oaks may be replaced by some species of fruit-trees.
CARoline.—I am not talking of replanting the forest,
but of that which would naturally spring up were the
15%
74 ON ROTATION OF CROPS.
first cut down. Now we know that aspen and fruit-trees
will not germinate from acorns.
MRs. B.—It is the acorns which will not germinate in
a soil so ill prepared for them; while the seed of the as-
pen, or kernels of fruit-trees, which may chance to be
here and there intermixed with the oaks, will find a soil
so well adapted to them that they will germinate readily
and grow rapidly. Thus a wood of aspen and fruit-trees
will succeed to one of oaks; but, after a long course of
years, the old stumps and roots of oak, favoured by the
exudations of the forest of a different family, will shoot
out, and, in the end, supplant the new forest, and a second
forest of oaks will be re-established, but not till after an
assolement of trees of another family. You see, there-
fore, that Nature occasionally makes successive as well
as simultaneous assolements.
CARolin E.--This is very curious. I did not conceive
it possible for an assolement to take place where industry
did not interfere with the natural course of vegetation.
But this succession of crops must change once a century
rather than once a year.
MRs. B.-They are doubtless of very long duration.
The assolements of trees which occur in the course of
agriculture are of a more transitory nature: they are ge-
nerally made with a view to improve new soil, in order to
prepare it for cultivation, such as the simultaneous as-
solement of broom and pines in the Campine of Belgium.
These shrubs enrich the soil for the future cultivation of
grain, both by their exudations and by the manure formed
from their leaves.
I have seen a very singular assolement in the neigh-
bourhood of the Rhine, consisting of alternations of vine
and clover. After a period of twelve years the vines are
grubbed up, and clover sown for three or four years.
But the most remarkable assolement is that of water.
There are some districts in France in which the low
grounds are laid under water for the period of a twelve-
month, and this is renewed every seven years.
CARoll NE.-What harvest can be obtained from such
a culture, unless it be fish
ON ROTATION OF CROPS. 175
MRs. B.-Fish and wild fowl form, in fact, the only
produce, while the land is under water. This mode of
culture has the advantage of draining the surrounding
country, and of favouring the production of aquatic
plants, which afford food for a prodigious quantity of
worms and insects. All these productions, whether ani-
mal or vegetable, leave their relics at the bottom of the
sheet of water; and, when it is drawn off, the land re-
mains covered with an abundant stock of the richest ma-
nure. There are many ponds of this description in the
country of Bresse in the Lyonois. If the water with
which these parts abound were more generally diffused,
they would become marshy and unwholesome; for it is
the scum of superficial stagnant waters which is delete.
rious, not the evaporation of deep waters. On the other
hand, were these ponds permanent, their deposition of
rich manure would either be lost, or could be drawn out
only at a great expense; while, if you change the locality
of these ponds, by drawing off the water to another spot,
the manure remains ready spread on the soil, and the
farmer has only to plough it in and sow his seed. The wa-
ter, in the mean time occupies another low land, where,
in its turn, it accumulates and deposits its riches: with
the assistance of locks, it is thus made to perambulate
through the valleys and low lands. Great care is taken
to preserve the young fish, and transfer them to their new
basins; for these, like the sheep of the meadow, not only
supply us with food, but enrich the soil for future vegeta-
ble produce.
I was once present at the operation of drawing off a
sheet of water, of no less than seven hundred acres in
extent. It was in the month of October. During the
preceding summer, fish had been caught and wild fowl
killed in prodigious abundance; but when the secrets of
the prison-house were exposed to view, it afforded a very
curious spectacle. The markets of all the nighbourhood
were supplied with full-grown fish; the young fry were
sold to stock other ponds; and rich and ample were the
remnants of animal and vegetable manure which pre-
ared the ground for culture the fellowing season.
Simultaneous assolements are as advantageous to warm
176 ON ROTATION OF CROPS.
countries as successive assolements are in our northern
climates. The circumstance chiefly to be attended to in
this mode of culture is, that the two crops should seek
their nourishment at different depths; thus the vine and.
corn may be raised together, the roots of the vine being
much longer than those of corn.
EMILY.—In Italy we have seen them continually ac-
companying each other: strips of corn separating the
rows of vines trained on trees; which latter also com.
pose a part of the assolement.
Mrs. B.-The vine is sometimes twined around the
olive, whose roots strike still deeper into the earth. For
the same reason, the peach and the almond are often
raised in vineyards; while apple and pear-trees would
not thrive, because their roots are as superficial and as
spreading as those of the vine.
CARoline.—Their shade might also be prejudicial,
while the foliage of the peach ahd the almond is compa-
ratively light.
Mrs. B.—The degree of shade must be regulated by
that of the temperature of the climate. In hot countries
leguminous plants succeed well interspersed with trees,
because their shade, by diminishing evaporation, retains
moisture in the soil. Thus corn thrives intermixed with
turnips and clover : the two latter, when young, requiring
the shade which the corn affords; and after it is reaped,
the sun is necessary to ripen them.
# Wheat and rye are sometimes sown promiscuously: it
is an old custom, and, I believe, a very bad one; both
plants being of the same family, their exudations are
noxious instead of advantageous to each other. Then
they do not ripen at the same period; so that when
reaped, the one must be over-ripe, or the other not come
to maturity. If the intent be to make bread of these two
species of corn, it would be preferable to mix the grain
after the harvest; indeed, it would be best to keep them
separate till after grinding, for, not being of equal size
and hardness, a loss is also experienced in grinding them
together.
CAROLINE.-It is customary, also, in sowing grasses
for forage to mix a great variety together.
ON ROTATION OF CROPS. 177
Mrs. B.-It is supposed that the species which is best
adapted to the soil will thrive so well as to choke the
others; but it would be a more judicious mode of pro-
ceeding, to try by experiment, which kind of grass was
best suited to the soil, and sow that alone.
On the confines of the cultivation of vineyards, that is
to say, in those latitudes where the vine with difficulty
ripens, the cultivator aims at producing a large quantity
rather than a superior quality of wine. For this purpose
the vines are frequently trained on trees, which multiplies
the fruit at the expense of its flavour.
CARoline.—It is singular that the same mode should
be resorted to, in climates which are too cold, as well as
in those which are too hot for the vine. In Italy they are
trained on trees, to afford them shade ; but on the cold
confines, shade must be very prejudicial, more so, I should
have thought, than would be compensated by the increase
of production.
MRs. B.—On the limits of the vine countries, the great
demand for common wine, in order to avoid the expense
of its carriage from more distant parts, ensures a sale for
wines of the lowest description.
Maize or Indian corn forms an assolement with peas and
|French beans : it affords a support to these climbing
plants; and, being of the grass tribe, its exudations are
favourable to leguminous plants.
Exily.—It is inconceivable what an abundance of
produce the earth yields under the influence of a southern
sun. In Tuscany we have seen flourishing together, in
the most perfect harmony of culture, the olive, the vine,
corn, and a variety of leguminous plants.
Mrs. B.-And yet the soil of Tuscany is not very fa.
vourable to vegetation. It is, indeed, well cultivated, the
Tuscans, after the Belgians, being esteemed among the
best of agriculturists; and they have, as you observe, the
advantage of a most prolific sun. It is for this reason
that they, in common with the cultivators in warm climates,
aim at producing a numerous simultaneous assolement;
while the Belgians, with the inhabitants of other temperate
climes, must content themselves with a succession of
178 ON ROTATION OF CROPS.
crops. The assolements of a Belgic farm, we have ob.
served, extend from ten to fifteen years, the farm consist-
ing generally of about forty acres; in Tuscany they are
ausually circumscribed to fourteen acres, with a soil infe.
rior to that of Belgium; yet the more ardent sun of Italy
produces a result nearly similar. In Tuscany the farmer
is not obliged to rear his crops in slow succession; they
are poured upon him, as it were, from the cornucopiae of
abundance : oranges, lemons, olives, melons, peaches,
corn, and vegetables spring up together, to delight his
eyes and to heap his board.
It is remarkable that these two countries, now so dis-
tinguished for agriculture, were once no less celebrated
for their commerce.
EMILY.—This seems reversing the natural order of
things; for, in general, it is the abundance of agricultu-
ral produce which leads to the establishment of manufac-
tures and trade.
Mrs. B.-That is certainly the most usual mode of
progressive improvement. . On the other hand, when a
people enrich themselves by commerce, it is a very na-
tural consequence that they should lay out some of their
wealth in the improvement of land. Then it so hap-
pened, that, as Europe advanced in arts and civilisation,
commerce, which began first to flourish in Tuscany and
Belgium, and was, indeed, almost exclusively confined to
those countries, became more generally diffused. Politi-
cal events also tended to diminish the trade of these
countries; and, when it fell into decay, agriculture
proved a fortunate resource for the wealth and industry
of the people. They transferred to this employment not
only their capital but that spirit of speculative enterprise,
wisely regulated by those habits of calculation and of or-
der, which distinguished them as merchants; and, when
engaged in any hazardous experiments, the regularity of
their accounts gave them exact results, and showed them
whether they ought to be prosecuted or abandoned. This
union of energetic vigour and methodical arrangement
has achieved the wonderful enterprises of these excellent
agriculturists,
THE PROPAGATION OF PLANTS, ETC. 179
ON THE MULTIPLICATION OF PLANTS.
CONVERSATION XV.
UN THE PROPAGATION OF PLANTS BY SUBDIVISION.
MRs. B.—It is now time to turn our attention from the
preparation of the soil to the study of the plants which
are to be raised in it.
CARoll NE.-After having provided suitable accommo-
dation for their reception, and an abundant store of food
for their subsistence, they will no doubt increase and mul-
tiply with rapidity.
Mrs. B.-That is not all. If we have taken so much
pains to provide for the welfare of the vegetable creation,
it is with the interested view of its affording us food and
raiment: "we shall therefore select for cultivation such
plants as are best suited to that purpose. º
There are two modes of propagating vegetables: the
first consists in subdividing the parts of a plant, so that
from one individual several may be formed; the second
mode is that of raising new plants by the germination of
the seed. ſº . . . ſº
In order to be able in every case to distinguish these
two processes, you must observe that the seed is always
contained in an envelope, and that it is prepared by or-
gans exclusively destined for that purpose. These or-
gans compose the flower or blossom. Now the plant
which results from the germination of the seed, is always
of the same species as that in which the seed originated;
but varying from it frequently in the quality of its fruit,
and not inheriting any of the peculiarities which may
have casually distinguished the individual parent-plant.
When, on the contrary, a new plant is raised by sepa.
rating from the parent-stock a slip or a layer, you not only
produce an individual of the same species, but, if I may
so express it, a continuation of the same plant, possessing
every peculiarity by which it may casually be distin-
guished from others of its species.
180 THIE PROPAGATION OF PLANTS
EMILY.—When these peculiarities are of an advan-
tageous nature, it must be desirable to raise the plant by
division; otherwise, I suppose, it is more easily accom-
plished by sowing the seed.
Mrs. B.-But the process is much more tardy. A
seedling tree of ten years’ growth will perhaps not be
more advanced than one raised by a slip of five years
old; then, when you are provided with a plant which
bears remarkably fine fruit, you are sure that if propa-
gated by division it will produce fruit of equally good
quality. This mode affords, therefore, the most certain
means of improving the species.
CAROLINE.-Re-production by seed is the mode adopted
by Nature; that by division the invention of art.
MRs. B.-The latter is also sometimes employed by
Nature, as you will see.
Re-production by division tends to diminish the quan-
tity of seed. The vine, which in a state of nature, bears
five seeds in each grape, when propagated by this mode,
has only two ; and some vines lose them entirely, so as to
leave no possibility of re-producing the plant but by divi-
sion.
EMILY.—The fruit no doubt profits by this deficiency
of seed, as the sustenance which would go to ripen the
seed, will be expended in enriching the juices of the
grape. I have observed that apples and oranges, which
have the fewest pips, are the highest flavoured.
MRs. B.-The remark is applicable to fruits in gene-
ral. The sugar-cane, propagated by division, wholly
loses its seed; and so do also the succulent plants of the
Cape of Good Hope, after having been for a number of
years transplanted into Europe.
CARoLINE.—But I cannot comprehend how a slip can
strike root. That root, branch, and every part of a
plant should be developed by the germination of a seed,
in which it existed in a latent state, is easy to conceive :
but that a root should grow from the extremity of a young
shoot seems to favour the idea of casual re-production.
which is not to be met with in Nature. d
BY SUBDIVISION. 181
MIRs. B.-There is reason to suppose that germs, in
some respect analogous to those which are contained in
the seed, exist in almost every part of a plant, but are
not developed unless placed under favourable circum-
stances; that these germs are of two distinct species,
the one producing stems, the other roots. The former
originate chiefly in the axilla of the leaf, or part which
unites the leaf to the stem; and which, from the analogy
it bears to the union of the arm to the body in the human
frame, is called the axilla: the latter shoot out roots on
each side.
It has been affirmed that roots may, by exposure to
the air, be converted into branches; and branches, by
being buried in the earth, transformed into roots; and
this, as I believe I before mentioned to you, has been at-
tempted to be proved by overturning a willow, burying
the head in the ground, and leaving the roots upwards
exposed to the air. But what was the result? Not that
the branches became roots, and the roots branches; for
the former being unfurnished with the organs of absorp.
tion, and the latter with those of evaporation, it was im-
possible for them to exchange their respective functions;
but the branches being deprived under ground both of
light and air, and of all the circumstances favourable to
the developement of the germs of other branches, these
branches do not shoot. The same circumstances being,
on the other hand, particularly adapted to the develope.
ment of the germs of roots, these strike out into the soil.
In the mean time the roots, which have been compelled
to change places with the branches, being exposed to
the light and air, and so situated as to favour the deve-
lopement of the germs of branches, in direct opposition
to that of the germs of roots, shoot out young branches
from their naked roots, and in the course of time cover
them with foliage.
Exily.—I recollect having seen the leaf of a plant,
which, when simply laid upon moist ground, struck out
roots from its edges into the soil.
MRs. B.-This is the Bryophyllam: the flower is the
only part of a plant which is incapable of developing
16
182 THE PROPAGATION OF PLANTS
either a root or a stem, except through the medium of the
seed, the production of which is its sole and exclusive
function.
. There are three modes of multiplying plants by divi.
$10n 3-
The first by layers;
The second by scions, or slips;
The third by grafts.
When you intend to multiply by subdivision, you place
that portion of the plant which you intend to separate
from the remainder under such circumstances as are re-
quisite to enable it to develope the organs in which it is
deficient, and which are necessary to its independent
existence. If it be a branch, the organ wanting is a
root; if it be a root, the organ necessary to be developed
is a stem. How is this to be accomplished?
EMILY.—You must, I suppose, bury the extremity of
the branch in moist ground, to favour the developement
of roots; and, in the other case, train the roots above
ground to encourage that of branches.
Mrs. B.-Exactly. It is the cambium, you must
recollect, which, in its retrograde course through the
liber, and partly through the alburnum, nourishes these
germs; if, therefore, you propose to develope them in
any particular part of the plant, you must accumulate the
cambium in that spot. This may be done in several
different ways. . In the first place, you may make an
annular incision in the bark or rind, and, by thus impeding
the descent of the cambium, accumulate it in the upper
section, where it will produce a swelling or protuberance
of the bark. The germs situated in the neighbourhood
of this rich magazine of food, if in other respects favoura-
bly circumstanced, are developed; that is to say, if the
annular incision be exposed to light and air, the germs of
branches will shoot; if below ground, those of roots will
strike into the soil. Indeed any casual interference with
the descent of the cambium is almost immediately followed
by the sprouting of a bud. In order to make a layer, you
bend down a pliant branch without separating it from the
plant, and fasten it in the ground; sometimes a slight
BY SUBIOIVISION. 183
incision is made at the spot in which it is confined.—Now,
what follows? The cambium, descending through the
branch, finds some difficulty in returning to the stem :
this obstacle is sufficient to occasion a small accumulation,
and the shooting out of several germs of roots.
There are some creeping plants which propagate them.
selves in this manner without the aid of man. Their
lower branches, trailing upon the ground, are often par.
tially covered with earth washed over them by the rain :
if, in this operation, they are slightly wounded by friction,
or the contact of any hard substance, such as gravel or
pebbles, the free passage of the cambium is interrupted,
roots strike out, and the branch which connected them
with the parent-stock, being in a great measure deprived
of its nourishment by the young roots, rots and perishes ;
the separation is thus made, and the requisite organs
being developed, the layer becomes a new individual
plant.
CAROLINE.-I have seen carnations and ranunculuses
thus propagated; and I am delighted to hear the expla-
nation of an operation I have often witnessed without
understanding it.
Mrs. B.--Laurels and most evergreens are also pro-
pagated by layers; and it is the regular mode used in
vineyards. A branch of vine is layed under ground, and
the extremity of it raised up above the soil in that spot
where you wish to produce a new plant. If the branch
be long and pliable, several plants may be made to spring
from it. This is called a serpentine layer, because the
branch takes a serpentine direction; being made alter-
mately to sink below and rise above ground, as often as it
is intended that new roots and stems should shoot from it.
Layers are sometimes made in arches, by burying the
extremity of the branch only; the separation is afterwards
made when the branch has struck root : this mode is
particularly suited to the raspberry, and every species of
bramble.
CARolin E.—I have heard that there is a tree in Senegal
called the Mangrove, or Rhizophora, whose branches,
descending to the ground, bury their extremities in the
184 THE PROPAGATION OF PLANTS
soil, and strike root, thus forming beautiful natural arcades
around the parent stem.
Mrs. B.-Several fig-trees in the East Indies grow
and propagate in the same manner. The ancients some-
times twisted the branch at the spot where they wished a
root to strike: for this process we have substituted the
more gentle mode of strangulation by ligatures, which
injures the branch less, and yet arrests the cambium
sufficiently to produce an accumulation.
Another mode of making layers consists in slitting the
branch from the bottom upwards, and drawing the portion
slit on one side, so as to form the figure of a Y reversed,
the branches being of unequal length. The portion of
the cambium which descends into the slit, finding no vent.
accumulates and strikes root.
ExILY.—I have seen the gardener propagate the Mag-
nolia, and other rare and delicate plants, by gently bend.
ing some of their most pliant branches to the ground, and
covering every part of them with earth excepting their
extremities ; by this means a considerable number of
layers may be obtained at a time.
MRs. B.-Layers are also sometimes made completely
above ground, though, it is true, this cannot be done
without the aid of the soil; for it is necessary that the
branch should be surrounded with moist earth, which may
be contained either in a flower-pot or a small basket,
having an opening sufficiently large to admit of the branch
passing through it.
CAROLINE.-The germs then strike root in this soil. I
have seen the Oleander propagated this way.
Mrs. B.-M. Humboldt, the celebrated naturalist.
when travelling in America, provided himself with strips
of coarse pitched cloth, which he substituted in the place
of a basket, to confine the earth round branches from
which he wished to make layers. He adjusted them
round the branches of trees in forests through which he
intended to return some months afterwards, when the
roots would have shot out; and by this means he brought
over to Europe a number of very curious and valuable
new plants, which have not only enriched our botanicat
BY SUBDIVISION. 185
gardens, but have been generally disseminated both for
use and ornament. ©
The most favourable season for propagating by layers,
in these temperate latitudes, is the latter end of February
or the beginning of March. This season is called by
gardeners the first spring: it precedes the ascent of the
sap, and enables the layers to collect the first drops of
cambium which are elaborated. In England and other
northern climates, where vegetation is less forward, the
end of March, which is called the second spring, is suffi-
ciently early for this purpose. The month of April, in
which the budding of the leaf takes place, is denominated
the third spring.
The safest way to ensure the success of layers, is to
leave them a year without separating them from the pa-
rent stock, in order to give them the chance of striking
root during the ascent of the autumnal sap, if they have
failed to do so in the spring.
Both succulent and aqueous plants are very difficult to
propagate by layers; because the cambium, instead of
forming a protuberance to nourish the germs, runs out
and is lost. The operation is more likely to succeed on
plants of this description by strangulation than by incision.
The propagation of plants by slips, is very analogous
to that of iayers; indeed the only difference is, that the
branch you destine to become a new plant is separated
from the parent stem previous to the developement of
those organs which are necessary to ensure it an inde-
pendent existence.
CARoll NE.-I am much better acquainted with this
species of propagation, I have raised so many geraniums
by slips. Nothing is more easy: you merely cut off a
young branch, and plant it in a pot of earth. But I am
completely ignorant how it lives : whether it absorbs
water before it strikes root, or whether it nourishes the
embryo roots by its own substance.
MRs. B.—I believe no one can boast of having a per-
fect knowledge of the process; but I am inclined to think,
that the cambium which descends in the slip, and which
was destined to nourish the lower part of the branch
I6*
186 THE PROPAGATION OF PLANTS
whence it was cut, finding a sudden termination to its
course, exudes. The first drops fall into the soil; but,
from its viscous nature, those which follow soon coagulate
and heal the wound. The protuberance then forms, and
roots strike out.
CARoll NE.-This process must, however, be attended
with much greater uncertainty than by layers. The slip,
being separated from its parent before it is able to provide
for its own wants, is like a child brought up by hand;
while the layer is weaned only after it has acquired the
power and the means of finding its own nourishment.
Mrs. B.-It is for this reason that the propagation of
rare plants is preferable by layers. There are some trees
which have such a remarkable facility for sprouting, that
whatever part of them you plant in the ground will strike
root, be it a branch, the remnant of a stem, or even a sim-
ple stake. The willow, the ash, and most trees of white
wood, sprout with this facility. The weeping willow is so
easily propagated by slips that it is never raised by seed;
and all the willows now existing in Europe, and, in all
probability, that ever will exist there, are subdivisions of
one tree brought originally from Asia.
ExIILY.—Green-house plants are usually propagated
by slips from shoots of the preceding spring; and some-
times the slip is cut a little below the spring-shoot, so as
to include a piece of the shoot of the preceding year.
MRs. B.-This is for the purpose of preventing the ex-
travasation of the cambium, the wood of two years'
growth being of a more solid texture.
Branches of three or four years' growth are sometimes
planted: they should be placed deep in the soil, to favour
the developement of a number of germs. Slips of forked
branches are planted with advantage for hedges, as their
. interlace each other, and form an impenetrable
€Il Ce,
In raising succulent plants by means of slips, it is.ne-
cessary either to dry up or cover with mastic the cut end.
for the purpose of retaining the cambium: in the isles of
France and of Bourbon it is usual to carbonise the ends of
slips in order to prevent its escape.


BY SUBDIVISION. 187
When you propagate by slips of roots, you must plant
them near the surface, in order to facilitate the sprouting
of stems. Jessamine, strawberries, and, probably, mush-
rooms, are propagated in this manner.
EMILY.—I thought that mushrooms were propagated
by a species of seed called the spawn.
MRs. B.-The white filaments, vulgarly called the
spawn of mushrooms, are in fact the fibres of its roots:
these are cut in pieces and sown; or rather, I should say,
planted in a hot-bed.

CARoline.—In planting potatoes, is it not requisite to
leave a spot, called an eye, in each piece It is from
these, I understand, that both stems and branches sprout.
Mrs. B.-These eyes are the germs of embryo stems
and roots. The potatoe is nothing more than a tubercle
formed by an accumulation of cambium in the subterra-
neous branches of the plant, and destined to nourish the
buds which are to be developed the following season.
This storehouse of food offers such facility to germination,
that when potatoes are heaped in a cellar, .# a moderate
degree of temperature and moisture, the germs absorb
nourishment from the farina of the potatoe and sprout,
either roots or stems, according as their situation favours
the developement of the one or the other of these germs.
CARoline.-In what an enviable situation these germs
are placed enclosed in a magazine of food–breathing,
as it were, an atmosphere of nourishment, and inhaling it
at every pore. e
Exſily.—Not more so than the germ of a bird, which
subsists on the yolk and albumen of the egg until its frame
is fully developed.
CARoll NE.-True ; it is singular what analogy there is
between the different productions of Nature, and what a
fund of knowledge may be derived from them'
MRs. B.-A fund equally inexhaustable and admirable!
We may consider the works of the creation as a natural
revelation, in which we read the history of the stupendous
operations of the Deity; and which, the more we study,
the more we raise our minds towards just ideas of their
Divine Author, and elevate our hearts by the contempla-
188 ON GRAFTING.
tion of the blessings he has so bountifully lavished upon
us. Not only are we provided with every thing necessary
to our existence, but care has been taken that even this,
our transitory state, should be rendered agreeable: our
food, instead of being insipid or loathsome, is delightful
to the palate; the landscape, spread before our eyes, in-
stead of being dark or monotonous, is illumined by a
splendid sun, and variegated by a thousand hues; delici-
ous odours arise from flowers of enchanting form and
colour; in a word, Nature contains innumerable sources
of enjoyment, which develope and strengthen a spirit of
grateful devotion towards their beneficent Author.
CONVERSATION XVI.
ON GRAFTING,
MRs. B.-We now proceed to the art of grafting, an
operation from which we derive our finest fruits. It con-
sists in placing a portion of one plant in juxta-position
with another, in such a manner that they shall unite and
grow together. The branch which is cut from one tree,
to be transferred to another, is called the graft, or scion,
and the tree to which it is transferred the stock.
CARolin E.-This then is not a mode of multiplying
plants, but of changing their nature; for if a branch of
one plant be added to another plant, the number is not
increased.
Mas. B.-Certainly not. The advantage of grafting
consists in improving the quality, not augmenting the
number, of plants. The ancients entertained very exag-
gerated ideas of this art : they conceived that every
species of plant might be grafted on each other; but it is
now well ascertained that this operation can be performed
only on plants of the same family. To ensure the suc-
cess of a graft, it is necessary that the vessels of the liber
of the two plants should meet and correspond, in order
that the cambium should descend from the graft into the
ON GRAFTING. 189
stock; for it is by the union of the vessels of the bark of
both plants that they are soldered, as it were, together.
CARoLINE.-Then endogenous plants, since they have
no bark, cannot be grafted 1
MRs. B.-No; at least that operation has not hitherto
been performed upon them with success.
Some anatomical analogy is also requisite in the form,
the structure, and dimensions of the vessels, which is
only to be met with, in plants of the same family. A
certain degree of physiological similarity is besides ne-
cessary; such, for instance, as that the sap in both plants
should rise at the same period. There must also be a
correspondence in the size and strength of the plants;
for instance, the lilac may be grafted on the ash ; but, as
the latter has a much greater power of suction, the graft
is gorged by the quantity of sap which is thrown up into
it, and dies of plethora. If, on the contrary, the ash be
grafted on the lilac, the graft perishes for want of nou.
rishment.
A plant which loses its leaves in winter cannot be
grafted (at least not without great difficulty) on an ever-
green : the latter, absorbing a sinall quantity of sap during
the winter, would send it up into the graft, which would
sprout, in a season in which the young shoots would be
destroyed by the frost.
CARoline.—And if, on the other hand, you were to
graft the evergreen on a plant which loses its leaves,
the graft would perish of famine.
MRs. B.-Very true; the last analogy required in
graſting is, that the two plants should thrive in the same
temperature.
When a tree is grafted, the graft will always bear its
own fruit, and the tree its own also.
EMILY.—I am surprised at that. Suppose that a
branch of cherry were to be grafted on a plum-tree:
the sap absorbed by the latter, rises through it into the
graft, and being elaborated in the leaves of the branch of
the cherry-tree, I should have supposed that it would
have changed the nature of the fruit of the plum-tree
when in its descent it returns into it,
190 ON GRAFTING.
Mrs. B.-No; for though the rising sap is the same
for both stock and graft, it is different in its return. The
sap of the stock and that of the graft are each elaborated
by their respective leaves, and, when converted into cam-
bium, each supplies nourishment to its own variety.
Mr. Knight has made many ingenious experiments,
which tend to show that each variety of fruit requires its
own peculiar leaves to bring it to perfection. He grafied
several varieties of apples and pears on trees of the same
species, and adjusted the grafts close above the flower-
buds on the stock: these buds blossomed and bore fruit
so long as leaves were suffered to remain on the tree ;
but in some experiments he stripped them off, so that the
sap could be elaborated only in those of the graft, and in
those instances the fruit always withered and fell off.
The principal advantage of grafting consists in its
affording an easy means of propogating individual plants,
which have, either by cultivation or some casual circum-
stance, attained a high degree of perfection.
EMILY.—This is similar to the advantages obtained by
the propagation of plants by layers or slips.
CARoline.-I have heard that it is necessary to graft
fruit-trees raised from seed, in order to make them bear
fruit: yet, if it were so, no fruit would grow wild; and
in a state of nature plants could not produce seed to con-
tinue their species.
MRs. B.-It is quite erroneous to suppose that .
fruit-trees will not bear fruit in due time; but this perio
will be considerably accelerated by grafting. A young
tree is not sufficiently strong during the first years of its
existence to bear fruit: an apple-tree, for instance, pro-
duces none until it has attained the age of ten or twelve
years; but, if grafted from a tree that has already borne
fruit, it will blossom and produce fruit sometimes as early
as the second or third year.
CARoll NE.-Yet grafting cannot increase the age or
strength of the seedling-tree ?
MRs. B.-No; but the buds on the graft have attained
a state of vigour and perfection which enables them to
produce seed; and the seedling-tree may be considered
ſº
ON GRAFTING. 191
merely as the channel by means of which nourishment is
conveyed to them, until age has given it sufficient vigour
to produce fruit-buds of its own. Grafting increases the
size of fruits at the expense of the seeds: the rose acacia,
when not grafted, bears seeds; when grafted, it bears
none, but its blossom is much finer.
Grafting sometimes produces a change of flavour, and
generally retards vegetation: it is often employed as a
means to retard that of trees, which bud so early in the
spring as to be in danger of suffering from the frost.
The walnut, for instance, buds a full fortnight later when
grafted on walnut.
In regard to the mechanical part of the process, care
must be taken to fasten the graft to the tree with soft
ligatures, and in such a manner that the vessels of the
respective barks may come into contact; then, in order
to prevent the extravasation of cambium, the wound must
be well covered over with a ball, which is generally made
of cow-dung and stiff clay. The composition which M.
De Candolle recommends for this purpose consists of one
pound of cow-dung half a pound of pitch, and half a
pound of yellow wax. *
The season for grafting is either in the spring during
the ascent of the sap, or in the autumn for the sap of the
following spring.
CARoline.—But does not the sap rise constantly
throughout the summer ?
MBs. B.-For the purposes of general vegetation it
does; but you must recollect that all germs and buds, are
fed by sap, elaborated by vessels appropriated exclusively
for that purpose; advantage must therefore be taken of
the period when this sap is in full flow, to effect the
junction of the two plants. le
M. Chondi has distinguished himself by the numerous
experiments he has made in the art of grafting : he
divides the plants susceptible of undergoing this opera.
tion into three classes: ſº
1. The Unitiges, or plants having one central and ver.
tical stem, such as firs, larches, and most evergreens.
In these it is the stem which must be grafted, and not the
lateral branches.
192 ON GRARTING,
2. The Omnitiges, every branch of which is equally a
stem, and therefore each is capable of being grafted.
3. The Multitiges, plants in which some branches are
stems and susceptible of being grafted, and others are
110t so.
M. Candolle once saw every branch of a large pear-
tree grafted : this was done in order to preserve a great
number of grafts, which had just been received from a
foreign country. The following year they were each
transferred to separate trees, and succeeded extremely
well.
EMILY.—And how are grafts, when brought from dis-
tant countries, preserved alive 7
MRs. B.-Frequently by dipping them into honey,
which, by preventing evaporation preserves the internal
moisture. Another mode is to bury the cut end of the
graft in a moist root, such as a carrot or a turnip.
It would be very difficult for me to explain all the
various manners of grafting, there being above a hun-
dred, which may be divided into three classes.
1. Grafting by approach. You bring together two
branches of two neighbouring trees, and cutting off the
extremities of each, you graft them together. If three
trees be united together in this manner, the stem of the
central one may be cut down, and the head will be kept
alive and nourished by its two neighbours.
CARoll NE.-This must be a safe mode of grafting rare
and delicate plants, as it is attended with no risk; for
suppose the junction does not take place, each branch
remains uninjured and grows separately, so that nothing
is lost.
MRs. B.-It is a good mode, also, for common plants,
being so easy and rapid in its results.
CAROLINE.-And might not in a similar manner several
stems be united to a single head?
MRs. B.—Yes; if a circle of stems of young poplars
be bent and united in a centre, they will form but one
head, which, nourished by the surrounding stems, will
grow to an enormous size.
Some trees graft themselves spontaneously. If two
ON GRAFTING. 193
branches of hornbeam happen to grow so close together
as to rub against each other when moved by the wind,
the outer bark will be worn away by the friction, and the
vessels of the two libers will come in contact, which is
sufficient to produce a graft. The mere act of two
branches growing contiguous, when confined for space,
will wound the bark; and, indeed, by whatever chance
the vessels of two branches are brought together, in such
a manner that the sap can flow from the one into the
other, a graft takes place.
EMILY.—You sometimes see a young tree growing
from the trunk of an old one of a different kind ; is this
the result of a natural graft?
Mrs. B.—No ; it is that of a seed which has sown it.
self, or of a slip which has planted itself in the hollow
of a decayed tree, the rotten wood producing a soil which
consists wholly of the richest nourishment. I have seen
a fine young cherry-tree grow out of the hollow trunk of
an oak, and a vine spring from the old stump of a
willow.
EMILY.—You sometimes see two leaves and two flow-
ers cohering together: is not this owing to a natural
graft
Mrs. B.-Yes; this species of grafting extends also
to fruits: the double cherry is thus grafted.
CARoline.-Pray, are roots susceptible of being thus
grafted?
Mrs. B.-It has been so affirmed, but it may probably
be an error, arising from confounding subterraneous
branches with roots.
The second mode of grafting, and which is in most
common use, is by scions: a young branch is cut off
from one plant, and grafted on another. In whatever
manner the section be made in the graft, one of a corres.
ponding form must be made into the subject, in order that
they may fit into each other, and the vessels of the liber
come into contact; the union then takes place in the
course of a few days.
EMILY.—The mode of grafting by approach bears a
17
194 ON GRAFTING,
considerable analogy to the propagation by layers; and
that by scions, to the propagation by slips or cuttings.
MRs. B.-True ; and the third class, which is grafting
bourgeons or buds, may in some respects be compared to
propagation by seed: it consists in transplanting a bud
from one plant to another. For this purpose the bud
must be separated from the parent-plant, in such a manner
as to be surrounded by a small disk or shield of bark;
for since the union is effected by the vessels of the bark,
it is through its intervention alone that the bud can be
grafted. A small piece of the alburnum is sometimes
cut off in addition to the bark, but I believe this to be an
unnecessary precaution. The bud may be adjusted on
any part of the bark of the tree, but it is more sure to
succeed, if it be grafted on a spot where another bud had
previously existed, in order that the vessels which con-
ducted nourishment into the original bud, may pour it into
that which is substituted in its place. In this manner Mr.
Tschudy has succeeded in grafting herbaceous plants,
the melon, for instance, on the gourd; and potatoes on
tomatas; but one herb cannot be grafted upon another.
This species of grafting is rather novel, it being formerly
supposed that herbaceous plants were not susceptible of
being grafted.
The embryos of buds, before they begin to be deve-
loped, you may recollect, are called eyes; and the graft
may be made either when the eye is said to be sleeping
or waking : that is to say, either in autumn, when the
eye is closed for its long winter-night of repose; or in
spring, when it is open for its summer-day of activity.
Another mode of grafting buds is by transplanting a
broad ring or flute of bark, containing several eyes, and
substituting it in the place of a similar ring cut away
from the stock: this is less sure of success, on account of
the number of buds to be nourished.
These several modes of propagation by layers, by slips,
and by grafts, are all calculated to improve the fruit; the
grand source of the multiplication of plants is the seed.
which we shall enter upon at our next interview.
TIIE FLOWER. 195
CONVERSATION XVII.
( )N TIIE MULTIPLICATION OF PLANTS BY SEED.-
THE FLOWER.
Mrs. B.—We have now reached that part of our sub-
ject with which you thought it would have been proper to
have commenced—the history of the seed. It will be
necessary to introduce it by a description of the organs
. office it is to prepare this important part of the
plant.
CARolin E.-That is to say, the flower, which forms
the principal part of the study of botanists in general,
and which we have hitherto totally neglected.
MRs. B.-If I have allowed the most beautiful part of
the vegetable creation to remain so long unnoticed, it was
in order that, when I described it, your interest might be
excited, not merely by the brilliancy of its colours, the
elegance of its form, or the sweetness of its perfume,
but that, having acquired some previous knowledge of
the economy of vegetation, and become acquainted with
the essential part it performs among the works of nature,
you would take a deeper and more rational interest both
in the blossom and the seed, and that your admiration
would be excited by learning, that the most beautiful part
of the vegetable kingdom, prepares and ushers into life,
that which is most useful. No child has so richly orna-
mented a cradle as the seed when reposing within the
recesses of the flower.
The flower consists of several parts.
The calyx, or flower cup, forms the external integu-
ment which shelters and protects the bud before it ex-
pands: it consists of several parts, called sepales, re-
sembling small leaves, both in form and colour; and pro-
bably performs similar functions, being furnished with
stomas. These sepales are, in general, more or less
soldered together, sometimes so completely as to form a
cup apparently of one piece: hence the calyx has ac-
quired the name of flower-cup.
196 THE FLOWER,
CAROLINE.-I see that you persevere in deriving every
organ of a plant from the budding of leaves.
MRs. B.-When you are a little more acquainted with
plants, I think that you will concur with me in this opinion.
Above the calyx rises the corolla, which is the coloured
part of the flower. It is composed of several petals,
either distinct and separate, or cohering so as to form a
corolla of one single piece : in the latter case the flower
is called monopetalous, though the petals are never ori-
ginally simple, as this name would seem to imply, but,
like the calyx, derive their origin from a circle or whorl
of leaves. When the petals first burst from the calyx,
and expand in all their beauty, they still serve to protect
the central parts of the flower: they are at first curved
inwards, forming a concavity around the delicate organs
which occupy the centre, which not only shelters them
from external injury, but reflects the sun's rays upon
them like a concave mirror, thus rearing them as it were
in a hot-house. When they are full grown, the artificial
heat being no longer necessary, and the admission of
light and air not only safe but advantageous, the petals
expand, leaving the internal organs exposed to the free
agency of these elements.
At the base of the petals is generally situated, the
nectary, so called from its secreting a sweet fluid, which
has been dignified by the name of nectar. This is the
store whence the bee derives honey: it affords also abun-
dant provision for the less provident insect tribe, who,
rioting in these sweets during a summer, scarcely outlive
the fall of the blossom. These thoughtless beings, how-
ever unwittingly, act a useful part in the economy of Na-
true, which I shall presently explain to you. The nectar
exists in almost all flowers, but is not always contained
in a distinct organ.
CARolin E.-I have often sucked it from the tubular
orifice of the petals of the honeysuckle.
Mrs. B.-That flower produces a great quantity of
honey, and part of it lodges in the elongated tube whence
ou suck it.
The most important parts of the flower are those deli,
TIHE FLOWER. 197
cate organs which occupy the centre as the place of
greatest security. It is here that the seed, which is to
propagate the plant, is lodged. It is enveloped in a small
leaf, which, instead of expanding its beauties to the sun
and air, like its neighbouring petals, folds itself more
closely around the little treasure it is to protect: the
edges of the two opposite halves of the leaf being thus
brought into contact, they unite and grow together, and
the leaf assumes the form of a pod, or vessel, the shape
of which varies according to the manner in which the
leaf was folded when it first budded.
CARollNE.—And will you not admit that plants have
sensibility, Mrs. B., when you see them showing such
signs of maternal care for their offspring 7
MRs., B.-No, my dear. Were I sufficiently versed
in the physiology of plants, I should no doubt be able to
show you, that this tender care of the protecting leaf is
the natural result of physical laws.
CARoll NE.-Then I am almost tempted to rejoice that
you are not learned enough to do so. I cannot help being
vexed when I hear facts, so interesting to the feelings.
explained away by the dry results of mechanical or
chemical laws.
MRs. B.-You are falling into an error very common
among half-learned and superficial observers.
When you feel inclined to murmur at the dry results
of physical laws, letnot your imagination rest there, but
raise your mind from these impassive agents, to their
Omnipotent Author: you will then consider them as the
unerring instruments which his paternal care has pro-
vided, to promote and secure the welfare of his creatures.
CARoll NE.-I now understand and perfectly acquiesce
in your sentiments. . It is very true that the mind, amazed
at the wisdom that is displayed in the laws of nature, is
apt to consider them as a sort of mechanical cause,
rather than as mere agents of an all-wise and sentient
Power.
MRs. B.—To return, then, to the flower and the en-
velope of the seed, in which, I trust, you will continue to
17+
198 THE FLOWER.
take some interest, although we have deprived it of sensi-
bility ;-unless in a poetic sense. When this leaf is
closed over the seed, and its edges soldered together, it
is called an ovary, or seed-vessel. From its summit rises
a little thread-like stalk, called a style, which, at its ex-
tremity, supports a small spongy substance, denominated
stigma. . These three parts form a whole, which bears the
name of carpel.
EMILY.—Is carpel, then, synonymous with pistil? For
I know that an ovary, with its style and stigma, consti-
tutes a pistil.
Mrs. B.-Pistils are composed, in general, of several
carpels, which, in most flowers, are so neatly fitted to
each other, and so closely adhere together, that they are
considered as a single organ, containing different cavi-
ties for seed; but the most accurate anatomical re-
searches prove that these several cavities have each its
style and stigma, and form distinct carpels: thus, the
blossom of the apple and the pear have several carpels
soldered together.
CARoline.-Oh, yes; for when they become fruits
they contain several seeds.
Mrs. B.-That would afford no proof of the pistil con-
sisting of more than one carpel, which often contains
many seeds; but in the apple and pear the seeds or pips
are lodged in separate carpels. It is true, however, that
a single carpel forms the pistil of some flowers; such, for
instance, is the blosom of the cherry, which, you know,
has but one seed, the kernel contained within the stone.
In some flowers, the styles and stigmas remain sepa-
rate, and the ovaries are soldered together: the flower
is then said to have two styles with one ovary, containing
several cells or cavities for seed; in others it is the styles
which adhere together while the ovaries are detached,
and in some few the adhesion takes place only between
the stigmas.
Immediately surrounding the pistil are situated the
stamens; each of which consists of a slender filament
supporting a little bag or case called anther, filled with
pollen, a species of dust or powder. The anthers when
THE FLOWER. 199
ripe, burst, and, being more elevated than the stigma,
shed their pollen upon it, and the seeds are thus perfected.
EMILY.—Yet I have heard that there are some plants
whose flowers have no stamens, and others which have
no pistils: in this case, how can the pollen of the stamens
fall upon the stigma of the pistils Nature has, no doubt,
provided some resource to overcome the difficulty.
Mrs. B.-Or, rather, it is a provision she has specially
made in favour of another part of the creation. The pollen
is sometimes conveyed by winged insects, which, in pene-
trating, by means of their long and pliant probosces,
within the recesses of the corrolla, in order to obtain the
nectar, cover their downy wings with the pollen.
This unheeded burden they convey to the next flower
on which they alight; and, in working their way to the
nectary, it is rubbed off and falls on the stigma; this
compensation, they make, for the honey of which the
rob the flower; and they thus unconsciously labour for
those plants, which afford them food. Every insect,
however ephemeral, every weed, however insignificant,
has its part assigned, in the great system of the universe.
In Persia, very few of the palm and date trees under
cultivation have stamens, those having pistils being pre-
ferred as alone yielding fruit. In the season of flower-
ing, the peasents gather branches of the wild palm-trees
whose blossoms contain stamens, and spread them over
those which are cultivated, in order that the pollen may
come in contact with the pistils and fructify the seeds.
There are two remarkable palm-trees in Italy, which
have been celebrated by the Neapolitan poet, Pontanus :
the one, situated at Otranto, has no stamens; the other
at Prindisi, which is about forty miles distant, has no
pistils, consequently neither of these trees bore seed; but
when, after the growth of many years, they rose superior
not only to all the trees of the neighbouring forests, but
overtopped all the buildings which intervened, the pollen
of the palm-tree at Brindisium was wafted by the wind to
the pistils of that at Otranto, and, to the astonishment of
every one, the latter bore fruit.
CARoli NE.-How extremely curious!
200 THE FLOWER.
Mrs. B.-IIaving now completed our examination of
the flower, it will be necessary to bestow some attention
on the stalk which supports it. This is called a peduncle,
or pedunculus. It generally expands a little at the sum-
mit, and forms a common base by which the several parts
of the flower are connected together. This little expan-
sion is called torus, which signifies a bed.
ExIILY.—It is the bed on which the flower reposes;
but it belongs to the stem, and, I believe, forms no part
of the flower
# MRs. B.--You are quite right: the flower consists of
the calyx, the corolla, the nectary, the pistil, and the
stamens. If you pluck off these several parts, the torus
will remain on the peduncle; but we shall see hereafter,
that, though it forms no part of the flower, it sometimes
enters into the composition of the fruit.
The peduncle is not always crowned by a flower: it
often branches out into a number of smaller flower-stalks
called pedicels, each of which supports a flower.
When pedicels diverge regularly from the summit of
the peduncle, as rays from a centre, it is called an umbel,
from the resemblance which the pedicels bear to the
branches of an umbrella. A second umbel frequently
shoots from each pedicel of the first; the umbel is then
said to be compound.
EMILY.—I observe that the peduncle expands, so as
to form a base for the pedicels which grow from it, and
this expansion is surrounded by a little circlet of leaves—
probably bracteas 1
MRs. B.-Yes they are, and are usually called the
involucrum of the umbel. The base whence the pedicels
radiate bears the name of receptacle; and it not only
serves to support them, but, the sap being accumulated
in this expansion, it becomes a reservoir of nourishment.
and supplies them with food which they each convey to
their respective flowers.
EMILY.—Does not the Laurustinus blossom in this
manner I have often observed that its peduncle spreads
out into a number of different ramifications.
MRs. B.-They do not spring from a common centre.
THE FLOWER. 201
and, consequently, can have no common receptacle; but
are irregular, like the branches of a tree, and the bunch
of flowers they support may be compared to its head. It
is hence called a cyme or cyma.
The peduncle often throws out small pedicels at regu-
lar distances, as you may have observed in a bunch of
currants: this sort of cluster is called raceme or racemus,
and its flowers open in succession from the bottom to the
top.
In some plants the flowers are placed around the pe-
duncle on such very short pedicels that they assume the
form of a spike or spica. When thus disposed they blow
in succession, so that those at the bottom of the spike
have withered before those at the top are unfolded. Plan-
tain blossoms in this manner. In other plants the flowers
are crowded still more closely around the peduncle, and
form an ear: such is the mode of flowering of corn and
grasses; in others, they grow in clusters or irregular
bunches like the vine. In many trees the peduncle as-
sumes the form of a spike, articulated with the branch,
and covered with the remains of degenerated bracteas,
resembling scales, under each of which a flower lies con-
cealed : the hazel, the willow, the alder, and the horn-
beam blossom in this manner.
EMILY.—I have paid so little attention to the manner
of flowering of plants, that I was not at all aware they
afforded so great a variety.
MRs. B.-I am far from having enumerated them all, for
every different modein which the pedicels diverge from the
main stem, and which produces a different arrangement
of flowers, bears its own peculiar name; but the whole
is included in the term inflorescence, which expresses the
various modes in which the stem of a flower is divided,
and, consequently, the arrangement of the flowers
upon it.
Plants blossom at regular periods; varying, however,
according to the temperature of the country in which
they grow, and the vicissitudes of the season. Linnaeus
formed a register of the season of flowering of different
plants, which he called the Calendar of Flora, but no al-
202 THE FLOWER,
lowance being made for these modifications, it is very ini-
perfect.
Exily.—I have observed that there are some trees
which regularly blossom earlier than others, of the same
species and in the same situation: whence does this
arise 7
MRs. B.-It is not ascertained; but as every pecu-
liarity of an individual plant is preserved when it is pro-
pagated by layers, slips, or grafts, advantage has been
taken of this anomaly to produce early vegetation, Mr.
Knight, by carefully selecting those potatoes which first
sprouted for replanting, obtained in the course of a few
years plantations of potatoes very considerably earlier
than the usual season.
In hot climates the fig-tree produces two crops of fruit;
and it is in some countries necessary to accelerate the
ripening of the first, in order to leave time for the second
to come to maturity, in due season. With this view, the
peasants in the isles of the Archipelago, where this fruit
abounds, bring branches of wild fig-trees in the spring,
which they spread over those that are cultivated.
Exſily.—This is, no doubt, the same process as that of
the fructification of the palm-trees in Persia.
Mrs. B.-It was long supposed to be so; but it is now
ascertained that the cases are quite different, the only use
of these wild branches being to serve as a vehicle to a
prodigious number of small insects, called cynips, which
perforate the figs in order to make a nest for their eggs,
and the wound they inflict accelerates the ripening of
the fruit nearly three weeks.
EMILY.-Does the insect produce this effect by the in.
jection of some stimulating fluid into the wound it makes,
or is it owing to the growth of the eggs it deposits 1
MRs. B.—The precocity does not appear to result from
either of these causes: it is, indeed, not well known;
but I should think may probably result from the punctures
of the insects, impeding the free course of the sap, and
roducing, like the annular section, an accumulation of
ap in those parts, which, by affording additional nourish-
THE FLOWER. 203
ment to the neighbouring buds, accelerate their develope-
Iſlent.
Have you not observed that fruits which are worm-
eaten ripen earliest ?
Extily.—Yes; but I thought that the worms attacked
those which were first ripe.
Mrs. B.—I do not allude to the external attacks of
worms and insects, but to the maggot born and bred
within the fruit; and the nest of eggs, whence it drew its
existence, was in all probability the cause of the preco-
city of the fruit.
Means may also be taken to retard the period of blos.
soming: too much nourishment is injurious at that sea-
son, and sometimes wholly prevents it. Much water is
also prejudicial : the water is drained from the rice
plantations when the rice is in flower; and the watering
of gardens should be diminished. Snow late in the
spring has, in mountainous countries, been known to re-
tard the blossoming of corn till the following year.
It is remarkable that the conveyance of plants from
one country to another appears to accelerate the period
of flowering; for plants brought from foreign climes
blossom earlier than usual, the first year of their emigra-
tion.
CARoll NE.-That is very singular. Can it be owing
to the excitement produced by the motion of the car-
riage 7
EMILY.–May it not rather be attributed to the total
cessation, of vegetation during the journey, when the
plant is confined by packing, and the consequent re-
action which takes place on its being replanted ?
Mrs. B.-It is a point very difficult to explain. It fre-
quently happens that, after blossoming, the fruit perishes
from debility. An anular incision of the bark (which you
may recollet arrests the cambium in its descent) increases
the vigour of the blossoms by affording them more nour.
ishment; but the ring, when made for this purpose, should
be very narrow, in order that the upper and under edges
of the severed bark may re-unite when this superabundance
of food is no longer required in the upper part of the plant.
204 THE FLOWER,
M. Lancris makes the ring of such narrow dimensions,
that the separation of the bark, lasts only during the flow.
ering of the plant; at the end of which period, the protu.
berance at the upper edge of the bark having swelled out,
till it reached the lower edge, and being still soft, the con-
tact and gentle friction produced by the continuance of
its swelling occasions it to burst: it then amalgamates
with the lower edge, when the wound is healed, and the
general circulation restored.
CARo11NE.—That is to say, that the upper edge of the
bark grafts itself upon the lower edge
MRs. B.-Precisely so. This operation has been per-
formed on the vine with some success; but these experi-
ments have not been sufficiently extensive for their gene-
ral results to be relied on. Its effect on fruit-trees, we
have already observed, is very precarious : the branches
of fruit-trees not being completely Iopped every year,
like those of the vine in vineyards, they are liable ulti-
mately to suffer from the derangement of the circulation.
It answers better with fruit-trees whose seeds are pippins,
such as the apple and the pear, than with such as have
stones and kernels, like the peach and the apricot, because
when the incision is made, the latter exude a gummyjuice,
so that they are liable to lose more than they gain by the
operation.
There is another cause which frequently prevents the
fruit from being formed. It is when water falls upon the
stamens : this makes them burst before the due season,
and the pollen, instead of being shed upon the pistil, is
lost. Rain, and even heavy mists, the latter of which,
still more than the former, insinuates itself into the flower,
very frequently produces this effect.
CAROLINE.-But all blossoms are exposed to mists and
showers: how then can any fruit be set !
MRs. B.-It is evident that nature has decorated plants
with a much greater number of blossoms than she de-
signed to convert into fruit; for the plant would have no
means of bringing so great a quantity to maturity. Look
at an apple or a cherry ree in blossom, and you will
observe, that were every flower to produce a fruit, not
THE FLOWER. 205
only would it be impossible for the tree to nourish so
great a crop, but even its branches would be unable to
sustain them. Therefore, though every shower may
destroy, or rathcr prevent the formation of a quantity of
fruit, it would require heavy and continued rains to prove
fatal to the whole. This however sometimes happens,
particularly to the vine, which in wine countries is a very
serious calamity.
I have still some further observations to make on
flowers, but I think you have learnt as much to-day as
you can well remember; we will, therefore, reserve what
remains to be said on them, till we meet again. In the
mean time you may refresh your memory on what I have
taught you, by examining this drawing [Plate I.] in which
the various organs of a plant are delineated in the repre-
sentation of a pea.
The second drawing [Plate II.] represents a plant of
the class of Monocotyledons of the liliaceous family, in
which it is a disputed point, whether the coloured part of
the flower is a corolla or a calyx.
ExIILY.—It has, surely, much more the appearance of
a corolla composed of six petals, than of a calyx consisting
of six folioles. One of these two organs, then, is wanting
in this family
Mrs. B.-In order to avoid error by deciding which
of them it is, botanists call the coloured part of a flower
of this description a perigone or perianth composed of one
or more pieces; that of the tulip has six.
18
&
a.º.
PLATE I.
THE COMMON PEA,
Pisum vulgaris; Leguminous family, Dicotyledon.
a, Stem.
b b, Stipula.
c c, Petiole, or common leaf stalk.
d d, Folioles of the compound leaf.
ee, Apex of the leaf.
ff, Tendril, terminating the petiole of the leaf.
gg, Peduncle or flower-stalk, springing from the axilla.
and dividing it into two pedicels.
i i, Pedicels. *
kk, Axilla of the leaf.
l, The flower.
mm, The calyx.
n n, The corolla.
o, The standard or superior petal.
pp, The two wings or lateral petals.
q, The carina, or two lower petals soldered togethel.
seen interiorly.
r, The torus, or base of the flower.
s, The stamens, nine of which are half soldered to-
gether by their filaments.
s', The tenth stamen free.
t t, The anthers.
vuw, The pistil—v, the ovary; u, the style: w, the stig- §
Ina, bearded.
r, The fruit or pod, of which a portion has been re-
moved in order to show the seeds.
3) y, The seeds attached to the upper suture of the peri.
carp.
zz, Firmeules or ligatures attaching the seeds to the
pericarp.
y, A seed detached. tººl
g", The cicatrice.
g", The seed split open, showing the embryo plant aná
the two cotyledons.
, The radicle.
BB, The two fleshy cotyledons.
C, The plumula.
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PLATE II.
WILD TULIP.
Tulipa sylvestris; family Liliaceous, Monocotyledon.
€t,
b,
Stem.
That part of the stem which forms the peduncle of
the flower.
cc c, Leaves. &
ºld, Flowers with six pieces disposed in two rows, bearing
or’
S 2
&f
9 *
the name of Perigone.
Torus, or base of the organs of the flower.
Filaments of the stamens bearded at their base.
The anthers.
The pistil composed of the ovary and the stigma,
having no style.
The ovary.
The stigma crowning the ovary, composed of three
cells.
C c, The pistil enlarged and grown into a fruit.
C cº, The cut open, to show the three cells, separated by
h,
h',
i,
k,
|
f
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lº,
6,
p,
partitions, and enclosing each two rows of seeds
attached to the centre of each cell.
A separate seed.
The same cut through lengthwise, to show the sper-
moderm, the albumen, and the embryon.
The spermoderm.
The albumen.
The embryon.
The embryon alone, showing it to be of one piece
or monocotyledon.
The bulb.
The base, representing the trunk or stem.
The roots.
A lateral branch.
PLATE III.
(49
b,
CHINA-ASTER,
Aster Chinensis; Syngenesious family, or Compound
Flower.
The stem.
A branch.
Leaves.
C C,
A head not blown.
A head in blossom.
Folioles composing the involucre.
Floral leaves, approximating to the form of the foll-
oles of the involucre.
Ligulate florets situated around the disk.
A single floret remaining on the head, all the others
being taken off.
Tubular florets situated on the disk or centre of th
head.
A single tubular floret remaining on the disk.
A ligulate floret magnified.
Tube of the calyx soldered on the ovary.
Edges of the calyx terminating in layers or pappus.
Ligulate petal terminating in fine teeth.
Two stigmas.
A tubular floret magnified.
Tube of the calyx soldered on the ovary.
Pappus crowning the calyx.
Tubular petal terminating in fine teeth.
Stigmas.
Upper part of the style bearing the stigmas.
The same magnified.
The lower part of the style.
The two stigmas enlarged to see the sweeping hairs.
Tubular petal split lengthways and spread open.
The fine filaments of the stamens.
The five anthers soldered together, and forming a
tube.
The fruit entire crowned by the pappus.
The fruit magnified.
The cicatrice, by which the fruit adheres to the re
ceptacle.
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PLATES.
{{...,
The border of calyx magnified, showing a single
hair truncated, inserted in a ring of teeth, the
rest of the hairs being pulled off.
The embryon, in which may be distinguished the
radicle and the two cotyledons.
Receptacle of the florets.
18°
206 ON COMPOUND FLOWERS.
CONVERSATION XVIII.
ON COMPOUND FLOWERS.
CARoll NE.—I have been studying your drawings Mrs.
B., and imagined that I understood them perfectly; but
when I attempted to make out the several parts on a real
flower, I am sorry to say that I found myself quite at a
loss.
MRs. B.-What flower did you choose for this purpose,
my dear? \
CARo1.1NE.—I was, perhaps, too confident of my powers
of discernment, for I selected one taat had a totally dif.
ferent appearance from the pea or the tulip : it was a
China-Aster. I made out a calyx and a corolla, but the
rest was all perplexity.
MRs. B.-You have fallen into an error which many
botanists have done hefore you : you took the China-Astel
for a single flower, while it is, in fact, an assemblage of
flowers, called in botany a head.
Here is a China-Aster I have just gathered: let us
examine it. [See Plate III.] The stem or peduncle is
terminated by what you call a flower, and what I call a
head of flowers. The extremity of the peduncle, you see,
expands into a white disk, called a receptacle, analogous
to the receptacle of the umbel, and in this all the florets
are inserted: it is not only the basis on which they rest,
but serves them also as a magazine of food. In the China-
Aster it is flat, but in many other plants of the same family
it is more or less convex: it is sometimes as thin as a sheet
of paper, as in the Scorzonera; at others, it is very fleshy.
as in the artichoke.
EMILY.—Is it that internal part of the artichoke on
which the choke rests, and which is so good to eat?
MRs. B.—Yes. Around the receptacle of the China-
Aster you see there are a considerable uumber of small
leaves, or bracteas.
CAROLINE.-That is what I supposed to be the calyx.
Mas. B.-It is a very natural mistake. It is, indeed, a
sort of calyx common to the whole head; but as each
ON COMPOUND FLOWERS. 207
floret has its separate calyx (and a calyx of so peculiar a
nature as not to be overlooked), thus common calyx is
distinguished by the name of involucrum, analogous to
the involucrum which surrounds the receptacle of the
umbel.
Exily.—There seems to be a considerable resemblance
between the umbel and the head of flowers ?
MRs. B.—That is very true. If you conceived the
branches of an umbel to be so extremely short that they
could not be distinguished, the umbel would be similar to
a head; and this is exactly the case of the Eryngiums.
EMILY.—The involucrum of the China-Aster differs,
however, in one respect from that of an umbel, the
bracteas of which it is composed being much more nu-
merous, and disposed in several rings or whorls around
the stem.
MRs. B.--That is the case with the greater number of
compound flowers, but it is not universal; for in the
Salsafy (Tragopogon), the Orthonna, and several others,
the bracteas, or, as they are more commonly called, the
folioles of the involucrum, are placed in a single ring.
When disposed in several rings, they are sometimes
equal; at others, vary in size: they are sometimes curled
up; at others, spread out. Some are soft, others scaly;
and there are some which terminate in a species of thorn
or prickle, as in the thistle. These varieties in the na-
ture of the folioles serve to distinguish the numerous class
of heads of flowers, which constitute no less than one-
twelfth part of the vegetable kingdom.
CARolliSE.—It is then, indeed, very necessary to make
acquaintance with so numerous a body of plants. But
you have mentioned both compound flowers, and flowers
growing in a head :-are these terms synonymous?
Mrs. B.-Certainly not; and I am obliged to you for
reminding me of a want of accuracy.
All flowers which shoot in numbers from a common
receptacle, either flat, or slightly elongated, are called
The flowers analogous to leaves without petioles, are
called sessile; such are the Scabiosa, and many others.
208 ON COMPOUND FLOWERS.
Now, among this extensive class, there is one family
distinguished from all the rest by the cohesion of their
anthers, so as to form a tube around the style, and it is
this peculiarity which constitutes the compound flower, or
family of Syngenesia; and it is to this family that I shall
more particularly direct your attention, as the China-Aster,
which we are examining, belongs to it.
You see all these little yellow parts in the centre of the
head, and these violet leaves which spread out around it,
and which you took for petals: they are all of them dis-
tinct flowers.
EMILY.-Is it possible !. Such a concourse of tiny
flowers, so closely crowded together in the centre; and
these appear totally different from the violet leaves, which
you also call flowers.
Mrs. B.-They are far from being so different in their
structure as you would imagine from their appearance.
In the China-Aster, and in several other of the Synge-
nesia, the florets, though distinct, are not separated from
each other by any intervening body; but there are some
plants of this family, such as the endive, the artichoke,
and the camomile, whose florets are separated by a spe-
cies of small bracteas, which have been called palix or
chaff and which shoot up from beneath each floret. These
bracteas are sometimes of a scaly nature, and sometimes
they assume the appearance of bristles or hairs. The
choke of the artichoke, before the blossom is developed,
is of this description.
EMILY.—The artichoke, then, is a compound flower:
and the only part of this plant that I am unacquainted
with is its blossom, which is not developed when it is
served at table. We there eat the receptacle and the
most tender part of the leaves which compose the involu-
cre, while the choke we carefully extract in order to avoid
eating it.
MRs. B.-I advise you, when an opportunity occurs, to
make acquaintance with the blossom. Let us now return
to the China-Aster: what l have hitherto told you relates
more to the mode of flowering; but we will examine the
structure of the flowers themselves. [Plate III.] Look
ON COMPOUND FLOWERS. 209
at one of those little yellow florets in the centre of the
head: with the assistance of this magnifying-glass you
will be able to follow me as I describe the different parts.
Observe, first, this white spot, which forms the basis of
the floret: it consists of the tube of the calyx, and con-
tains the ovary or seed-vessel to which it adheres.
CARoline.—The external part of this tiny tube, then,
is the calyx, and the internal part the ovary; but what
are those little hairs which crown the tube, and grow
from either the calyx or the ovary, I know not which
MRs. B.-They proceed from the margin of the calyx,
which assumes this singular appearance, because its
natural growth, in the form of sepals or leaves, is im-
peded by the pressure of the adjacent florets.
EMILY.—And I conceive that the calyx may be stinted
in its growth for want of food, as well as for want of room.
Mas B.-That may also produce some effect in check-
ing its growth; but the elongated form, which the edges
of the calyx assume, must be chiefly owing to pressure.
In some heads, in which the florets are not so crowded as
in the China-Aster, the calyx wears a more natural ap-
pearance, being shaped like a cup, and is of a membra-
naceous texture; in others, it resembles small scales: in
the present instance, and in most compound flowers, it
consists of a species of hairs, either seperate or glued to-
gether. It was formerly considered by botanists rather
as an appendage to the calyx than forming a part of it,
and was distinguished by the name of tuft or pappus ; and
though this name applies literally only to hairs, it has
been extended by analogy to all the various forms which
this organ is capable of assuming.
CARoline.—But this little feathery tuft appears much
more ornamental than useful : it cannot, I think, in such
a form, afford protection to the flower.
Mrs. B.—The florets, being so close together, protect
each other: the use of the tuft is to assist the fruit to dis-
engage itself from the involucrum, and then to transport
it to a distance; for the pappus remains upon the fruit
after the blossom has fallen. There are some few com-
und flowers the calyx of which is not at all elongated,
and which, consequently, have no pappus.
210 ON COMPOUND FLOWEBS.
EMILY.—How, then, does the fruit or seed disengage
itself from the involucrum ?
MRs. B.-When the tuft is wanting, the fruit is fur.
nished with other means of separating itself from the pa-
rent-plant. Sometimes the receptacle rises up after the
blossom is over, to force out the fruit; at others, the
weight of the head, when it is mature, bends the pendun-
culus, and the seeds fall to the ground. Thus you see
that every difficulty is foreseen and obviated in the ad-
inirable structure of which I am endeavouring to give you
a mere outline.
CARoline.—You speak sometimes of the fruit, and
sometimes of the seed, which the tuftwafts away : do you
mean to use these terms indifferently, or have they each
of them a distinct meaning?
MRs. B.-I was not quite correct in so expressing my-
self; but the error was very trifling, as you will perceive
when I have explained the difference to you. ... I said that
the small body, to which the tuft was attached, was com-
posed of the ovary and the calyx. The ovary contains a
single seed, which hrs its own particular covering, called
Spermoderm. Thus the single seed of each little flower
is enveloped in three integuments, adhering to each other
—the calyx, the ovaray, and the spermoderm. In some
compound flowers, these three integuments are distinctly
seen ; but in others they are only supposed to exist by
analogy, without being actually visible. These three in-
teguments, soldered together, form a peculiar species of
fruit, which was formerly called a naked seed, but is now
distinguished by the name of Achenium. In some fami-
lies (such, for instance, as the Epilobiums and the Apoci.
nums), small feathery tufts grow within the germen, and
are attached to the seed. These tufts bear the name of
Coma, and serve the same purpose as the pappus, though
their origin is different. But we are digressing from our
China-Aster.
EMILY.—Pray let us return to it; for it has become
very interesting, since I have learnt how much there is in
these little things which you call florets.
MRs. B.-Above the ovary, and within the pappus, you
ON CONPOUND FLOWERS. 211
may perceive a yellow tube, terminated by five small
teeth; this is the corolla. If you slit it up with the point
of a penknife, and look very close, you will see five little
stamina; they have each their filaments, which appear
to grow out of the tube of the corolla, and each of these
filaments is terminated by an anther.
CARoline.—I can see only one anther.
MRs. B.-Because the five anthers adhere together, so
as to form a cylindrical tube, through which passes the
style the extremity of which spreads out into two small
branches. It is this tube which constitutes a character-
istic distinction of the compound flower. The five an-
thers, of which this tube is composed, open internally by
two small slits. The style is also furnished with a pecu-
liar species of stiff hairs, called sweeping hairs; because
they are designed to sweep the pollen from off the an-
thers, so as to make it fall upon the stigma.
EMILY.—How wonderful that a little yellow atom.
which I hardly looked at, should contain so great a varie-
ty of curious organs !
MRs. B.-The more you study nature, the more beau-
tiful and magnificent it will appear. But we have not yet
done with the China-Aster. You understand the struc-
ture of the yellow central florets; but the purple ones.
which form the circumference, are very different.
CARoline.-In appearance, certainly they are , for
they look exactly like long narrow flat leaves.
MRs. B.-Pull out one of these violet leaves, and you
will see that the extremity, by which it is attached to the
receptacle, is not flat, but round and hollow, in the form
of a tube. Suppose it to be an elongated tube, slit
open lengthwise and spread out, and you will form a tol-
erable idea of this species of corolla. These are called
ligulate florets; ligula being Latin for a strap : hence they
frequently bear the name of strap-shaped florets.
CARoll NE.-At the upper extremity there are five
Small teeth, like those of the yellow tubes.
EMILY.—But here, Mrs. B., is another China-Aster, in
which there are no yellow florets; the head is entirely
212 ON COMPOUND FLOWERS.
composed of these flat violet florets, which we took for
petals.
MRs. B.-This is a double China Aster. All its florets
have undergone the change which in general takes place
only with those situated at the circumference of the head;
and you have here a proof of the two sorts of florets be-
ing of the same nature, since they are susceptible of be-
ing transformed from the one into the other. If you ex-
amine the flower attentively, you will see that the ligulate
florets have no stamens, and even the style often appears
imperfect; so that florets of this nature yield no seed, and
when a head is entirely composed of them, it is incapable
of propagation.
CAROLINE.-Yet here is a scorzonera which has only
flowers of this description, and it produces seed 7
Mrs. B.-I will explaim to you whence this difference
arises. Compound flowers exist in three different states:
—the head is sometimes composed entirely of tubular flo-
rets ; the artichoke and the thistle are of this description :
they are called flosculous, and, with some few peculiar
exceptions, all the florets yield seed. A second state is
when the head is composed entirely of ligulate florets,
having stamens and styles; such as the double China
Aster, you have just observed: these form the class call-
ed Ligulate, or, as they are sometimes, though less pro-
perly, called, Semi flosculous. The scarzonere and the
endive belong to this class, and all the florets yield seed.
In the third state, the florets in the centre of the head are
tubular, and those at the circumference flat or ligulate:
these are denominated Radiate. The dahlia, the aster
(including the China-Aster), the camomile, the daisy, and
many other plants, are comprehended in this division.
The central florets generally yield seed, while the late-
ral ones are barren. These varieties of structure, com-
bined with those which exist in the receptacle, the invo-
lucrum, and the pappus, have enabled botanists to sepa-
rate and divide into classes the numerous compound plants
which are spread over the face of the globe. There is
also a fourth state of compound flowers, in which the co-
rolla is divided into two lips; they are called Labiate flo-
ON FRUIT, 213
rek: , But I shall not enter into any details on this class,
as it is found only in America, and is very rare in the bo.
tanical gardens of Europe. e
EMILY.—I am glad that you spare my memory; for I
fear I shall have some trouble to recollect all you have
taught me concerning those which grow in Europe.
Mrs. B.-I assure you that I have endeavoured to
make the subject as easy as I possibly could, and have
omitted many difficult parts; but in this case, as in every
branch of botany, you will understand clearly, only by
seeing with your own eyes. Analyse the compound
flowers you meet with ; and when you have examined a
few, you will comprehend them better than all my expla.
nations will enable you to do. I do not pretend to make
you adepts in botany; I merely wish to direct your atten:
tion to the observation of the works of Nature : they will
speak for themselves, and in a language far more eloquent
than I possess.
CONVERSATION XIX.
ON FRUIT.
Mas. B.-It is now time for us to take leave of flowers,
and turn our attention to the fruits which they produce ;
in which state the seed may be considered as entering
unto a second stage of existence.
After the flower has performed its office of fructifying
the seed; the petals, and every organ which is not des:
tined to become a part of the fruit, wither and fall off.
In the mean time, the ovary grows, and gradually assumes
the appearance of a fruit.
EMILY.—Is the fruit, then, formed from the origina'
little leaf which so carefully guarded the seed when the
flower was in blossom, and which you called a carpel ?
MRs. B.-Yes; when it assumes the form of fruit, it is
frequently called by botanists pericarp.
CARol.INE.-But I suppose it retains the name of seed.
vessel, since it contains the seed in the fruit as well as in
the flower?
19
214 ON FRUIT,
MRs. B.-Certainly. Now let us take, for example,
one in which the form of the original leaf is not wholly
obliterated—this pod of a pea, for instance: you may
plainly see that it consists of a leaf doubled over the
seeds, with its edges united.
EMILY.—This pod, which is very young, is almost flat:
but here is a larger one, which is become convex, in order
to make room for the growth of the peas; and I perceive
that the older it grows, the more it loses the form and
appearance of a leaf.
CARoline.—In shelling peas, I have observed that the
pod readily opens where the edges of the leaf have been
soldered together; but if you attempt to sever the pod at
the opposite seam, which I suppose forms the midrib of
the leaf, it is much more difficult.
MRs. B.-You are mistaken there, my dear; for, in
shelling peas, the pod is opened by splitting asunder thr
midrib of the leaf. When the pod is ripe, this rib opens
of itself, and the opposite suture or seam, formed by the
soldering of the edges of the leaf, also gives way; so
that the pod is separated into two halves or valves, and
the seeds detach themselves and fall to the ground. This
is a natural mode of opening, for the purpose of shedding
their seed, which is common to a great number of peri-
carps: it is called dehiscence.
CARo11NE.—Then the peas, which I thought had been
attached to the midrib of the leaf, must grow from its
margin : that seems very singular. Is there any instance
of leaves, in their common state, bearing seeds thus?
Mrs. B.-Yes; a leaf has been discovered (the Bryo.
phyllum) which has this extraordinary property'; it bears
germs, susceptible of becoming young plants, and these
are situated on its margin, like the seeds in a carpel. The
same structure is found in the Malaris paludosa, a little
plant, growing occasionally in bogs in this country.
CARoline.—Well, it is not very difficult to comprehend
that a leaf may be converted into a pod, which you bota-
mists dignify with the name of fruit; but I cannot conceive
how you can metamorphose a leaf into what we ignorant
people call fruits; such as an apple, a cherry, or a plum.
ON FRUIT. 215
Mas. B-With a little further explanation, I hope I
shall be able to accomplish this. Do you recollect the
Structure of a leaf.
EMILY.—It has a smooth upper surface, and an under
surface more porous, of a rougher texture, and generally
downy or hairy. Between these surfaces lies the pabu-
lum, a softer body, consisting of an expansion of the cel-
lular system, and this is traversed and intersected by the
fibrous vessels which form the ribs of the leaf.
Mrs. B.-Extremely well. In the pea-pod these seve-
ral parts are distinguishable. The leaf is doubled upon
its upper surface, so as to render the under surface ex-
ternal.
EMILY.—The most porous surface must, of course,
form the outside of the pod, otherwise the stomas could
be of no use.
MRs. B.-This is the case not only with the pea but
with all carpels. The external surface takes the name
of epicarp:—the upper surface of the leaf forms this thin
delicate skin, which lines the interior of the pod : it is
called endocarp; and the pabulum of the leaf is this soft
intermediate layer, which is denominated mesocarp.
CARodrxe.—Oh, what hard words to remember, Mrs, B.:
MRs. B.—You will, perhaps, be able to retain them
more easily if I explain their derivation : carpos is the
Greek word for fruit, and epi for upon or over.
CARoLINE.-That clears up the whole difficulty: ſor it
is easy to understand that epicarp signifies the outside
skin which is upon the fruit; endocarp the inside skin;
and mesocarp, no doubt, means the middle substance
between the two. Now, if you will be so good as to tell
me the derivation of the word peri, I shall not forget the
meaning of pericarp.
MRs. B.-Peri signifies about or around; so pericarp
means about or around the fruit. According to this defi-
nition, the seed alone is considered as the fruit; but, in
the usual acceptation of botanists, the pericarp itself con-
stitutes the principal part of the fruit. g
A leaf, forming a carpel or pericarp, may be folded"

216 ON FRUIT,
a variety of ways, either cylindrical, or like a cornucopia,
or doubled a little convex like a pod; but, however diver-
sified the form of the fruit, it results always from the
manner in which the leaf was originally folded, when it
first budded.
Now, into what sort of fruit, do you wish that I should
convert one of these pericarps?
CARoline.—You speak with the same confidence, Mrs.
B., as if you were going to perform the metamorphosis
with a fairy's wand; and make me expect to see it ac-
complished, with the same facility that the pumpkin was
converted into a coach for Cinderella. However, I shall
endeavour to increase the difficulty of your task, by
making choice of a fruit which bears no kind of resem-
blance to a leaf-a peach, for instance. Will it not re-
quire the utmost effort of your art to effect this transfor-
mation ?
MRs. B.-Far from it; for the peach is one of the most
simple of fruits; it resembles the pea-pod, in being com-
posed of a single carpel, but it is still less complicated,
for the carpel contains but one seed—the kernel within
the stone. The skin is the epicarp. Do you, not recog-
nise the hairy cuticle of the under surface of the leaf in
in the downy skin of the peach 7 Then the cellular tex-
ture of the pabulum, absorbing a great quantity of sap,
and swelling out as it grows, forms the fleshy substance
of the fruit:-this is the mesocarp. Finally, the upper
surface of the leaf being, in a great measure, deprived of
moisture, and starved, as it were, by the voracious appe-
tite of the mesocarp, its fibres contract, become tough,
then indurated, and are at length converted into a shell
or hollow stone, which affords most secure shelter for the
Seed:—this is the endocarp.
CARoline.—What a very curious transformation
Every vestige of the ribs of the leaf is obliterated in the
fruit; but traces of contraction of the endocarp are dis-
cernible in the seams and wrinkles with which the stone
is covered.
EMILY-There are also indications of its being com-
posed of two valves, for a sharp instrument will split it
ON FRUIT. 21?
9Pen, and divide it into two parts, and, when it is diseased,
it separates of itself. Then the curved indenture, which
runs along the peach on one side, I think, points out the
seam of the carpel. And pray, Mrs. B., are all stone-
fruits formed in the same manner ?
MRs. B.-Yes, they are. This class are distinguished
by the name of Drupe or Drupa, among these you will,
perhaps, be surprised to hear, that the almond and the
cocoa-nut are classed.
EMILY.—They certainly bear very little apparent re-
semblance to fleshy stone-fruits, being wholly destitute of
a fleshy mesocarp.
MRs. B.-In these dry drupes, the mesocarp assumes
the form and texture of coarse thready fibres, which form
the external covering of the nut: the endocarp is the hard
woody nut, and the smooth skin with which it is covered
is the epicarp.
CARoline.—Who would ever have imagined that the
flesh of the peach, so delicate and luscious, and the coarse
fibres which enclose the almond, had both a similar ori-
gin ' I suppose, then, that it is the almond which absorbs
the chief part of the nourishment, for the whole of the
pericarp is dry and meagre.
EMILY.—Were fruits not so treacherous in their ap-
pearance, I should conclude that the apple and the pear
derived their fleshy substance, like the peach, from the
swelling out of the mesocarp; but I have so often been
mistaken in my conjectures, that I make the inquiry with
diffidence?
MRs. B.-You are right not to be too confident; for
the apple and pear are quite of a different description
from the drupe. But do not let us proceed too fast, and
by degrees I hope I shall be able to make you compre-
hend them all. I began by selecting the most simple
cases, in drder to be well understood; we must go on
upon the same plan; for in natural science we cannot, as
in chemistry, make experiments which gradually lead us
from the simplest to the most compound combinations;
but Nature makes these experiments for us, and our busi-
moss is only to orange the combinations she exhibits in
10’s
218 ON FRUIT.
methodical order. We have hitherto considered fruits
formed of a single carpel; but it is not difficult to con-
ceive that a fruit may be composed of several carpels.
Take, for example, this Poeny: it consists of a number of
carpels, each of which exactly resembles a fºod. You
recollect my telling you that the pistil of a ſlower was
commonly formed of several carpels: such flowers will
produce fruits of a similar number of carpels.
CARoline.—Oh, yes; and I recollect your saying that
this was the case with the apple and the pear.
MRs. B.-A little more patience: we are not yet ar-
rived at the apple and the pear.
EMILY.—But cannot you show us some other fruits
similar to that of the poeny ? for I see it is only by natu-
ral specimens that one can understand the curious trans-
formation of flowers into fruits. º
MRs. B.-It is very true, that it is necessary to observe
the flower in order to understand the conformation of the
fruit. Here is an apocynum : its flower bears two carpels.
which differ but little from a pod : these carpels are dis.
tinguished by the name of follicles. Here is another
example: it is a variety of the cherry, which, instead of
bearing a single drupe like the common cherry, bears
several.
We will now proceed another step, and examine the
raspberry: this fruit consists of a considerable number of
small fleshy carpels, all of which result from a single
flower. It resembles an aggregation of small drupes.
EMILY.—The number of carpels, then, I see offers no
difficulty: a flower may bear one carpel, like the pea;
or two, like the apocynum; or five, like the poeny; or a
still greater number, like the raspberry.
Mrs. B.-Now, examine this long narrow pericarp of
the wall-flower: of what number of carpels do you sup-
pose it consists?
CARoline.—Of only one, for it is a pod similar to that
of the pea or the bean;–but no, on opening it, I perceive
that a thin partition runs down the middle, which divides
it into two cavities, and that there is a row of seeds in
each. This pod must therefore consist of two carpels
growing together, so as to form but one fruit.
ON FRUIT, 219
, Mrs. B.-Pericarps of this description are called si-
ques, not pods. The pod belongs to the leguminous, the
silique to the cruciform family.
Extily.—We have seen many instances of the organs
of flowers being soldered together: the petals, for in-
stance, are frequently united so as to form a corolla of a
single piece; the stamens often, cohere together by their
filaments; the anthers are united so as to form a tube in
compound flowers; and it is not more difficult to conceive
that several carpels should be soldered together and form
fruits, having different cavities or cells for seed.
MRs. B.-You may consider it as a law of Nature.
that the number of cells for seed contained in a fruit,
implies the number of carpels soldered together in its
formation. This law, however, admits of exceptions,
which require some further explanation. The carpels,
you allow, consist of folded leaves: if these reach to
the centre of the fruit, the cells will be complete; if
they reach but half way, the centre will be hollow
and empty: for the partitions formed by the folding of
the leaves will only reach half way: of this the poppy is
an instance. If the leaves be still less folded, they will
spread out in growing, and the fruit, though composed of
several carpels, will only have one cell ; the melon is an
example of this kind.
EMILY.—How, then, can you distinguish a fruit that
has but one cell for seed, because it is formed but of one
carpel, from a fruit that has but one cell, though origi-
nally composed of several carpels?
CARollNe.—I think I can explain that. When the
fruit consists of one carpel only, the seed will be situated
in a row on one side of the carpel; but when it consists
of several carpels, there will be as many rows of seeds
as there are carpels, since each carpel bears its row of
sceds.
MRs. B.-You are right; but recollect that each row,
though apparently single, is in fact a double row, the
. being attached alternately to each valve of the
Well, now that you have seen and understood the
220 ON FRUIT,
result of the soldering of carpels together, and the effect
of the leaves of which they are composed being more or
less folded or curved inwards, you may readily conceive
that such differences are sufficient to account for the
various forms of fruits.
When the carpels are verticillate, that is to say, situated
around a common axis, or a little column, (called colu-
mella,) the divisions of the carpels often completely
disappear externally, and the fruit assumes a spherical
appearance; but if the convexity of the carpels be
greater than that of the whole fruit, each carpel protrudes
cxternally, forming a rib, such as those of the house-leek.
EMILY.—The shrub which is dignified by the name of
Paeony-tree, has the carpels of its fruit enclosed in a sort
of membrane, which covers them completely.
MRs. B.—This membrane, according to the celebrated
Mr. Brown, appears to be a prolongation of the torus,
or base of the stamens, which grows over the carpels,
and, in some instances, adheres to them; but this species
of conformation is very rare. One that is much more
common, but also more complicated, is when the carpels
not only cohere together, but are also soldered with the
calyx; so that when the blossom falls, the fruit which
grows is composed of the carpels and the calyx, forming
a single body.
EMILY.—This must produce a fruit of a very singular
appearance.
MRs. B.-Not so much so as you imagine; for the
apple and the pear are of this description. This mode of
growing can be easily understood when the fruit is traced
from its primitive existence in the flower; but I can
give you an infallible test to know whether the fruit, when
already grown, is of this description. You see the eye
at the top of this pear: it is formed by the remnants of
the sepals or leaves of the calyx; and whenever you see
such an eye at the summit of a fruit, you may be assured
that it consists of the carpel and the calyx soldered to.
gether. All fruits whose seeds are pips, are of this
nature, and are distinguished by the name of Pome.
ExIILY.—The quince, I am sure then, consists of the
ON FRUIT. 221
calyx soldered to the carpels, for it has a very large eye
but is the medlar also of this description ?—it has a con-
siderable opening at the top, somewhat resembling an eye-
Mrs. B.—Yes; and the aperture results from the
calyx not completely covering the carpels: these, there-
fore, are visible between the teeth or indentures which
terminate the calyx.
EMILY.—I see that the metamorphosis of a flower into
a fruit, is in many cases a very complicated affair, and
not so easy to understand as I had imagined from your
first explanation. Is it the calyx which forms the skin,
and the pericarp the flesh of the pome?
Mrs. B.-It is difficult to distinguish these organs,
when cohering together. The calyx, however, being
external, must naturally form the skin of the pome; part
of it may also enter into the composition of the flesh,
together with a portion of the pericarp. The heart or
core of the pome, consists of the endocarps of five carpels,
each containing two seeds or pips.
EMILY. —The orange has no eye; otherwise I should
have thought it had been a fruit of a similar construction.
Mrs. B.-Far from it; the orange is a pulpy, not a
fleshy fruit, like the pome or the drupe. Now pulp does
not, like flesh, result from the growth of the mesocarp,
but is a peculiar succulent substance, situated inside of
the carpels: those of the orange consist of the quarters
into which the fruit may be easily divided when the rind
is peeled off, and the seeds are imbedded in the pulp
contained within them. e
CARoline.—True: they are not lodged in a core, like
the apple or the pear; nor in a shell or nut, like the peach
or the plum. But might not a fruit have both flesh and
pulp ?
Mrs. B.-Yes; the quince is an instance of this com-
bination: the flesh is, like that of the pear, situated
outside the core or cells containing the seeds, and within
those cells the quince contains pulp; but this species of
complication is not common.
CAROLINE.-And pray, under what head do you class
222 ON FRUIT,
those fruits in which the seeds are promiscuously situated,
such as the gooseberry, the currant, and the grape
MRs. B.-They are distinguished by the name of
Bacca, or berry: in these the mesocarp is soft and suc-
culent. Although the seeds are attached to the endocarp,
yet the latter is obliterated when the fruit is ripe. A
strawberry is not properly so called, because it does not
belong to the class of berries. It consists of a fleshy
substance, formed by the expansion of the summit of the
edunculus, in which the several parts of the flower are
inserted, and which we have called the torus. The small
grains which you see upon its surface are so many little
carpels, each of which contains a seed.
CAROLINE.-They are so small and dry that they look
like naked seeds.
MRs. B.-The pericarp fits closely to the seed, so that
they seem to form but one body; but they may, thus
united, be considered as so many distinct little fruits,
imbedded in the soft substance of the torus.
CARolin E.-They would be very little appreciated as
such, were it not for the delicate flavour of this soft sub-
Stance.
MRs. B.-These little grains, though dry, are analo-
gous to the small fleshy spherical bodies which form the
raspberry; and the white conical substance which re-
mains upon the calyx of the raspberry, after the fruit is
pulled off, is analogous to the fleshy substance of the
strawberry; for they both result from the growth of the
torus.
CARo1.1NE.—With this difference: in one it is the
torus; in the other, the berry, or true fruit, which is good
to eat.
EMILY.—And is not the conical expansion of the torus,
on which the raspberry grows, analogous to the axis or
stalk which traverses the mulberry? For these two fruits
bear a great resemblance to each other.
MRs. B.-You are falling into an error to which every
one is liable who judges from the appearance of the fruit
without having previously studied the flower. If you ex.
ON FRUIT, 223
amine the blossom of the mulberry, you will see that it
consists of several small sessile florets disposed around
the axis; that each of these, after the blossom has fallen,
forms a distinct fruit, consisting of the carpel and the ca.
lyx; these fruits being fleshy, and situated so near to each
other as to come in contact in growing, cohere together;
so that a mulberry, which is in fact an aggregation of
several different fruits, proceeding from as many different
flowers, wears the same appearance as a raspberry,
which is the result of different carpels belonging to the
same flower.
EMILY.—There are, then, if I mistake not, no less than
four degrees of complication in the composition of a fruit.
First. Fruits formed by a single carpel, such as the .
pea or the peach.
Secondly. Those formed by several carpels, the pro-
duce of a single flower, like the paeony and the raspberry.
Thirdly. Those formed of several carpels, surrounded
by and soldered with the calyx, such as the apple and the
pear.
Fourthly. Those formed by the aggregation of several
fruits produced by different flowers.
MRs. B.-Your enumeration is perfectly correct. I
will give you some further examples of the latter de-
scription. The cone of a pine or fir tree consists of an
aggregation of fruits, produced by as many different
flowers, having each a single seed: these flowers are
separated from each other by bractea, which remain
after flowering : they grow tough and hard, and enclose
each of the fruits as it were in a case, the aggregation
of which forms the fir-cone.

FMILY.—This is a kind of fruit quite new to us; and
the come of the magnolia is, I suppose, of the same de-
scription.
MRs. B.—No ; the cone of the magnolia proceeds front
several carpels belongiug to the same flower. The dif.
ference is very difficuft to distinguish after the blossom is
over, and the fruit formed; but is easily observed if the
history of the fruit is ttraced from the period of blos-
soming.
224 ON FRUIT,
CARo1.INE,--It seems to me to be very difficult to avoid
error on so complicated a subject.
Mrs. B.-I cannot deny it; and I will give you another
instance of deceitful resemblance. Few things bear a
eater likeness to each other than the Spanish chesnut
castanea vesca) and the horse-chesnut (ſesculus hippocas-
tanum); yet the horse-chesnut is simply a seed, while
the Spanish chesnut is a fruit, consisting of two or more
seeds, each of which has its separate envelope, under the
form of a reddish-brown skin. The shell of the horse-
chesnut is a capsule propuced by a single flower. The
prickly covering of the Spanish chesnut is an involucrum,
which surrounded the several flowers. You see, there.
fore, that it is very difficult to decide upon the nature of
the fruit without having studied the flowers whence it de-
rives its origin.
Are you desirous to have another curious example of
the cohesion of fruits produced by different flowers ? It
is afforded in the pine-apple. This, which you have
doubtless hitherto considered as a single fruit, is the result
of the soldering of a number of small fruits, produced by
sessile flowers aggregated on an axis, which is the stalk.
These small fruits, being soft and fleshy, unite together ;
but traces of the different fruits are scen on the surface.
each forming a small protuberance: the axis of the fruit
terminates in a crown of leaves, which surmounts the whole.
CARolixE.—But where are the seeds 1
MRs. B.-Cultivation, I have told you, tends to diminish
the quantity of seed: in the pine-apple it makes them
fail completely, so that the plant can be propagated only
by the crown or by suckers. You may see towards the
centre of the pine-apple the vacant cells in which the
seeds have perished, and in which they are lodged in the
wild pine-apple, whose fruit is less succulent and less
highly flavoured.
From the pine-apple and the mulberry you may cón-
ceive a very good idea of the fruit of the bread-tree,
which supplies the inhabitants of the South Sea Islands
with food. It may be compared to a very large mulberry,
composed of aggregated fruits. When the seed fails,
which is the case in the Friendly Isles, the fruit grows to
ON FRUIT. 225
a prodigious size: when the seeds are perfected, it is in
a great measure at the expense of the fleshy part, whose
place they occupy, and the fruit is consequently inferior
both in size and flavour. This is the case with the wild
bread-tree (Artocarpus incisa.)
EMILY.—You have said that some carpels do not open
to shed their seeds : how, then, can these sow themselves
and germinate 7
MRs. B.-Fruits, in this respect, may be divided into
three classes.
First. Those which do not open, and which contain
but one, or at most a very few seeds; such are the fruits of
the gramineous family, and of compound flowers. They
are distinguished by the name of Pseudosperma, which
signifies false seeds; because, though they assume the
appearance of seeds, yet, being surrounded by their peri-
carp, they are in reality fruits, and in this state they are
sown and germinate.
Secondly. Those fleshy fruits which do not open na-
turally; these in the course of time become rotten, and
thus disengage their seeds.
Thirdly. Fruits which are not fleshy, and which con-
tain a number of seeds, are collectively distinguished by
the name of capsular or dehiscent fruits. These open na-
turally and shed their seeds, which are dispersed in fall-
ing, and thus have a greater chance of germinating.
CARolisE.—This classification of fruits is more easy
to comprehend than the others.
MRs. B.-True, but it is much less important; for,
instead of explaining the essence of things, it shows only
the consequences. It is, however, far from being devoid
of interest; but I shall enter into no further details: it is
better to rest satisfied with the knowledge of a few prin-
ciples, which I trust you will find no difficulty in applying
to the different plants which may come under your notice.
I can never sufficiently repeat, what my professor of
botany has so often observed, that natural history can be
learned but in a very imperfect manner in books; and
that, in order to obtain a competent knowledge of objects.
they must be studied in nature.
20
226
CONVERSATION XX.
ON THE SEED.
MRs. B.-Before we proceed to treat of the germina-
tion of the seed, we must examine its internal structure.
A seed may be considered as a germ situated at the axilla
of a leaf.
CARoline.—Of that famous little leaf which performs
so great a part in the flower and the fruit, and undergoes
as many transformations as harlequin in a pantomime !
MRS. B.-No; the one I allude to is another little leaf,
which adheres so closely to the germ as to form the coat-
ing of the seed itself: it is called the Spermoderm, from
two Greek words, sperma, signifying seed, and derma,
skin.
The spermoderm, like the the pericarp, is composed of
three coats.
ExIILY.—Derived, no doubt, from the two surfaces,
and the pabulum of the leaf, of which it is formed.
MRs. B.-Precisely. The external skin, called Tesla
or cuticle, corresponds with the epicarp; the cellular coat-
ing, denominated Mesosperm, with the mesocarp; and the
internal skin, called Endopleura, represents the endocarp.
When this leaf first shoots, it is hollow, and contains
a nutritive juice called Amnios : the germ attached to its
axilla, when fructified, begins to absorb this fluid : it takes
the name of embryo ; and is, in fact, a plant in miniature.
In proportion as the amnios diminishes, the embryo fills
out and occupies the vacant'space: in the course of time
it grows so large as to distend the spermoderm itself.
Here is a very young bean: I slit open the spermoderm,
and you see the embryo plant surrounded by the amnios.
ExIILY.—But it is the miniature of a bean, not that of
a plant.
MRs. B.—It is the cotyledons of the embryo plant
which form the greatest part of this little bean: the ra-
dicle and plumula are enclosed within them, and are not
ON THE SEED, 227
sufficiently developed to be distinguished without the aid
of a microscope. But here is a full-grown bean, in which
the embryo occupies the whole interior of the spermo-
derm, the amnios having been all absorbed. Now, if you
separate the cotyledons, you will perceive the skeleton of
the plant lodged between them, and making a slight in-
denture in either cotyledon.
CARolinic.—I see it perfectly ; but it is not in the
centre of the bean.
Mrs. B.-No ; it is situated at that end by which the
bean was connected with the pod by a short pedicel.
This spot is commonly called the eye or hilum of the
seed. The pedicel conveys nourishment to the embryo
plant. When the seed is ripe, this communication ceases,
the pedicel withers and dries, and the seed detaches itself.
This scar which you see on the testa, and which inter-
rupts its uniform smoothness, is made by the rupture of
the pedicel, and is always considered as the base of the
seed; and you may still perceive the small aperture
through which the nutritive juices passed into the seed.
EMILY.—But is not the embryo plant nourslied by ab-
sorbing the amnios ?
Mrs. B.-Not wholly; for you must consider that it
not only requires food for its immediate sustenance, but
lays up a store of provision in its cotyledons, which is re-
serve. for its future growth at the period of germination.
CARQLINE,--I always thought thº' those little threads
which fastened peas and beans to the pods were merely
to prevent their rolling about in the shell; but now I see
that it is necessary they should have a communication
with the pod, for the conveyance of nourishment.
EMILY.—What vessels in miniature these must be
I know nothing more curious than the extreme, I may al-
most say the invisible, minuteness of some of the organs
of plants.
MRs. B.-In some seeds, the whole of the amnios is
consumed by the embryo plant; in others, the absorption
of this liquid is only partial: the most fluid parts pass into
the embryo, while the more solid particles, being probably
too bulky to traverse such minute vessels, are i:

228 ON THE SEED,
in the interior of the seed. This substance is, at first,
of the colour and consistence of the white of an egg, and
has thence acquired the name of albumen: but, as the
seed approaches maturity, it coagulates, and adheres to
the endopleur, lining it throughout with a white concrete
substance, and, indeed, filling the whole of the space
which is not occupied by the embryo plant. This is a
resource afforded by Nature for the germination of seeds
which have not a sufficient store of food in their fleshy
cotyledons.
CARoline.-But Peas and beans are so well supplied
by these cotyledons, that they are in no want of such re-
SOUly'C{},
MRs. B.-Very true : the whole of the leguminous
and the cruciform family, as well as several others, have
no albumen. But the gramineous family, which includes
all the various species of corn and grasses, are in great
need of this auxiliary; for not only do they belong to the
class of monocotyledons, but their single cotyledon is so
small, that, although slightly fleshy, it affords but very
little nourishment. But let us seek for an example on a
larger scale:—you have, I dare say, eaten the white sub-
stance which lines the shell of the cocoa-nut 7
CARoline.—Frequently: it has the consistence, and
somewhat the taste, of an almond. This, then, is albu-
men; but what is the water that fills the cavity of the
nut?—It cannot be the more fluid part of the amnios, as
this, you say, is absorbed when the albumen is deposited.
MRs. B.-The seed of the cocoa-nut is very large, and
the embryo plant very small ; so that the latter cannot
absorb the whole of the amnios, and it is the residue which
constitutes the water of the cocoa-nut. Albumen, you
will observe, does not, like the cotyledons, constitute a
part of the embryo plant; it is merely a deposition of
food for its use. The embryo is in general much larger
in seeds which have no albumen.
CARoll NE.-Of course, such embryos carry their store
of food about them, as a snail carries its house upon its
back : they must therefore occupy more space; and, the
whole cavity within the spermoderm being vacant, they
have more space to occupy.
ON THE SEED. 229
MRs. B.-All that is contained within the spermoderm,
whether it consist of the embryo plant and albumen, or
whether of the embryo plant alone, is called the nucleus,
kernel, or almond of the seed.
EMILY.—The amnios, then, either in its entire sub-
stance, or a fluid secretion from it, is destined to feed the
embryo plant, while the young seed is embosomed in the
flower. The albumen and cotyledons afford a coarser
sort of food, reserved for the future nourishment of the
seed when it germinates.
MRs. B.--So Nature designed it; but art converts the
greater part of this coarser sort of food into nourishment
for a superior order of beings. In peas and beans it is
the fleshy cotyledons that we cat; in corn it is the albu-
men of the seed which supplies us with bread.
CARo1.1NE.—But in peas and beans it is the seed itself
we eat, not the cotyledons !
MRs. B.-The cotyledons form the principal part of the
seed; of those, at least, which have no albumen. If, in-
stead of eating them when young, we allowed them to
ripen &nd germinate, the pea and the bean would sepa-
rate into two parts, and assume the form of cotyledons.
EMILY.—We then rob the young plant of its destined
food
Mrs. B.—No doubt we do. If corn were not reaped,
the grain would fall into the ground, and, there germi.
nating, the albumen of the seed would be expended in
nourishing the young plants; but when these plants struck
root, the soil would be unable to maintain a crop so thickly
•own: many seeds would perish for want of food, and the
rest, being but imperfectly supplied, few or none would
ome to perfection. Man, therefore, deserves no re.
proach, even from the vegetable kingdom, when he scat-
ters the seed in such quantity only as the soil can nourish,
and reserves the remainder for his own use.
EMILY.—It appears to me surprising, that the embryo
plant, after having been in an active state of vegetation
while the seed remained within the flower and the fruit,
should become, as it were, dormant when the seed is
20%
230 ON THE SEED,
mature, and separated from the plant; nay, should often
remain so for a long period of timé.
MRs. B.-The principle of life, it is true, can be pre-
served in some seeds a great number of years; but what
that living state is, which so nearly resembles death, we
cannot explain. It is time, however, for us to rouse the
inactive seed from its torpid state, and examine it, when
it enters into a new existence, as a separate and inde-
pendent being.
ExIII.Y.—True ; we have hitherto considered only the
formation of the seed, and its growth in the flower and
the fruit.
MRs. B.-Let us now, then, suppose it to have attain-
ed a state of maturity, and ready, when placed under
favourable circumstances, to germinate. For this pur-
pose the seed must first be detached from the parent
plant.
CARo1.1NE.—That is what we every day witness. The
fruit, when ripe, drops from the tree; or the pericarps,
when dry, burst open, and shed their seeds.
MRs. B.-Not always: some pericarps, we have ob.
served, have no natural mode of opening ; such is the
nut, the amaranth, the pericarps of compound flowers,
and those of gramineous plants. In the latter, the peri-
carp adheres so strongly to the seed, that they are con-
ſounded together, and cannot be distinguished. The
seed is, in this case, inaccurately sº id to be naked ; when
ripe, it falls from the stem, inclosed in the pericarp, and.
thus covered, sows itself in the ground.

CARo11NE:-Then I think that seeds of this description
should be called clothed, rather than naked.
MRs. B.-They are so, in fact; but as the pericarp is
of a hard, dry nature, and adheres closely to the seed, it
is commonly considered as forming a part of it. Thus
the seeds of corn and grasses are sown enclosed in their
pericarps.
ExIILY.—Then the pericarp, I suppose, rots in the
ground, and the seed is left at liberty to germinate 1
MRs. B.-The pericarp untimately rots, but not until
Platerv.
//www.x:///www.re.

PLATE IV.
Fig. 1.
(ERMINATION OF A MONOCOTYLEDON, OR DNDOGE-
NOUS PLANT.
The Scheuchzeria palustris.
a, Pivot or radicle.
bb, Accessory roots shooting from the bottom of the
Stern.
c. Cotyledon or first leaf.
d d", Second and third leaves, called primordial.
r c, Common leaves of the plant.
Fig. 2.
|IORIZONTAL SECTION OF THE STEM OF A MONOCO-
TYLEDON, OR ENDOGENOUS PLANT.
Yucca aloifolia.
Showing the scattered fibres which compose the
wood, having neither bark, pith, medullary rays,
nor distinct layers.
Fig. 3.
(iPRMINATION OF A DICotyledoN, OR EXOGENOU’s
PLANT.
Daubnentonia punica.
4, Radicle slightly branching.
h, Neck or vital point between the root and the stem.
f, Portion of the stem below the cotyledons.
T, Portion of the stem above the cotyledons.
cº, Two opposite cotyledons.
A simple primordial leaf.
d,
ff. Common leaves.
PLATES,
*
Fig. 4.
V LRTICAL SECTION OF THE STEM OF A DICOTYLEDON,
OR EXOGENOUS PLANT.
The Oak.
a b, The bark, composed of the vertical layers a, and
the internal bark b.
de, The wood, composed of the alburnum or young
wood c, the perfect wood d, and the pith e.
The circular zones represent the layers of wood,
and the lines diverging from the centre the
Inedullary rays.
Fig. 5.
A BRANCII TURNING ITS LEAVES TOWARDS THF
LIGHT.
ON THE SEED. 231
the germ has made its escape through a small aperture,
which nature has provided for that purpose. That of a
grain of corn is too minute to be seen with the naked eye;
but you may probably have observed three openings of
this description in the cocoa-nut, a seed of sufficient size
for them to have attracted your attention. Through one
of these the embryo escapes from its prison.
EMILY.—But the stem and the root cannot both shoot
from the same opening, or they would both grow in the
same direction ?
MRs. B.-The radicle first sprouts from the aperture
with the neck situated at its base ; from this vital spot the
plumula shoots upwards; but the young plant remains
attached to the pericarp by the neck, until it has consum-
ed the albumen of the seed, and is able to supply itself
with food from the soil.
It is thus that monocotyledons are ushered into life.
The germination of dicotyledons is somewhat different.
The seed is not enveloped in its pericarp, and, when it
begins to germinate, the spermoderm cracks and falls off;
the cotyledons, commonly called the lobes of the seed,
are split asunder by the stem which rises between them;
but, like a careful parent, they follow their nursling at its
entrance into life, and continue to supply it with food un-
til its roots are sufficiently strong to perform that office.
The embryo plant, consists, then, of three parts : the
radicle, or root ; the plumula, or little stem; and the co-
tyledons, or seminal leaves, which make their appearance
at the base of this stem.
The first and most essential circumstance requisite for
germination is moisture ; for a seed, in germinating, ab-
sorbs about once and a half its weight of water.
ExIILY.—This is, no doubt, for the purpose of soften-
ing and dissolving the hardened contents of the cotyle.
dons, and rendering them sufficiently limpid to pass through
the minute vessels which convey them into the embryo
plant.
MRs. B.-Yes; moisture is equally necessary, whether
the germinating plant be fed by the farinaceous matter of
the cotyledons or by albumen; for seeds, when ripe, you
232 ON THE SEED,
know, are perfectly dry, or if they contain any water, it
is not in a state of liquidity, but solid, like the water of
crystallisation in mineral salts. If seeds are deficient in
inoisture, they are, on the other hand, overladen with
carbon, so that you must supply them with water, and free
them from a portion of their carbon, to enable them to
germinate. It is the great quantity of carbon which seeds
require in ripening that exhausts the soil in which they
grow.
CARollse.—But for what purpose do they require this
‘iccumulation of carbon, since they must part with it in
order to germinate 1
Mrs. B.-Carbon is a great antiputrescent, and is ne-
cessary to prevent the seed from rotting previous to being
sown. Some seeds are, through its influence, capable of
being preserved several centuries; while others, which
are but scantily supplied with it, must be sown as soon as
ripe. And in seeds which have not acquired a due supply
of this preservative, the principle of life is extinguished
before they separate from the parent plant.
EMILY.—With a view of ascertaining whether seeds
are capable of germinating, I have seen gardeners throw
them into water; discard those which swam on the sur-
face as worthless, and sow only those which sunk. They
judged by the weight of the seed, I suppose, whether it
contained a sufficient quantity of carbon to have preserved
the vital principle.
MRs. B.-Or, rather, they know by experience that
heavy seeds are the most likely to germinate. Immersing
seeds in water has also the advantage of preparing them
for germination, by supplying them with the moisture of
which they stand so much in need.
EMILY, -And it is, I suppose, the oxygen of the atmo-
sphere which performs the office of relieving them from
the excess of that element with which they are encum-
bered
Mrs. B.-Yes; it is therefore necessary that the soil
should lie loosely and lightly over the seed, in order that
the air should have access to it. The oxygen of the at-
mosphere then combines with the carbon of the seed, and
ON THE SEED, 233
carries it off in the form of carbonic acid gas. Seeds
will germinate in contact with air which contains from one
eighth to one third of oxygen: if the proportion be less,
it will be insufficient to perform the function required; if
more, the excitement will be too great, and the seed will
perish from exhaustion.
EMILY.—The proportion of one fifth of oxygen, which
the atmosphere contains, is, then, just the desirable medi-
um. , And heat, I conclude, is also essential to germina-
tion?
MRs. B.--To a certain degree : seeds cannot germi-
nate during a frost, for the water must be in a liquid state :
about ten degrees of Reaumur, or fifty-five of Fahrenheit,
is the temperature most favourable to the germination of
plants in these climates. It is, moreover, requisite that
the soil should be sufficiently permeable for the slender
plumula, and the tender roots, when first shooting from
the seed, to penetrate it; and, on the other hand, it must
be sufficiently compact to support the roots and stem when
full grown. The looser the soil is, the deeper the seed
should be sown, in order to afford more support.
EMILY.—And in very loose soils the air has freer ac-
cess, so that there is no danger of depriving the seed of
oxygen by sowing it deep. Large seeds, I suppose, re-
quire to be sown deeper than small ones?
Mas. B.-Yes; but the largest should not be buried
more than six inches in the ground, in order that the air
may have access to them. Small seeds require to be
merely covered with earth, in order to prevent the wind
from scattering them, and to shelter thcin, in some mea-
sure, from the light.
CARoline.-Is light, then, injurious to germination ?
Mrs. B.-The function of light you may recollect, is
to subtract oxygen from the plant, and occasion a deposi-
tion of carbon. Now, in germination, it is just the reverse
which is to be effected.
When the seed by absorption, has accumulated a suf.
ficient quantity of moisture, it swells, bursts, the radicle
shoots downwards, and the plumula rises in the opposite
direction: the one becomes a root, the other a stem; and
234 ON THE SEED,
the almond of the seed is transformed into cotyledons.
If any of these parts are destroyed, the plant is no doubt
injured, but Nature will restore them by fresh shoots.
The neck, or vital spot which forms the junction between
the stem and the root, being the only part, the destruction
of which proves fatal to the plant.
EMILY.—Is it known why the stem always rises, and
the root descends?
MRs. B.—The roots, you must recollect, grow only at
their extremities; and these, being at first of so soft a
texture as to be almost liquid, naturally follow the direc-
tion of gravity and descend, unless they encounter some
obstacle, such as a stone or clod of earth, so compact that
they cannot penetrate it; in which case they grow out la-
terally, in order to avoid what they cannot overcome.
Mr. Knight performed a very curious experiment, with
the view of ascertaining whether it was gravity which
made the roots of a plant grow downwards. He sowed
seeds in moss disposed in cavities, arranged on the cir-
cumference of a water wheel. The cavities were open
on both sides, so that the root and the stem were free to
germinate at either. The wheel was then made to revolve
one hundred and sixty times in a minute. The roots in-
variably struck in the direction diverging from the centre,
like the spokes of a wheel: whence Mr. Knight was led
to conclude, that, in this artificial process, the centrifugal
force had replaced that of gravity.
ExIILY.—That was a most ingenious contrivance. But
the stem, on the contrary, grows upwards, and throughout
its length.
MEs. B.-Let us suppose that it were free to grow in
any direction. Since it shoots from the upper surface of
the neck, it cannot grow downwards: it must, therefore,
either rise vertically, or shoot outsideways. In the latter
case, it will be gradually brought to a vertical direction by
the same cause which makes branches tend to grow up-
right; that is to say, the fluids which circulate in the stem
having naturally a tendency downwards, some portion,
however small, will exude from the upper to the under
side of the lateral stem; so that the lower, being more
ON THE SEED, 235
amply supplied with juices, will vegetate with more vigour,
and grow larger. The diminutive upper side will act like
the cord of a bow, and make the stem approximate to.
wards a vertical direction ; and this cause, continuing to
act on the stem so long as it is not upright, will ultimately
render it erect.
Let us now consider more particularly how seed should
be sown, both in the fields and in gardens. In the for-
mer, the husbandman must prepare the land by ploughing,
in order to render it as light as possible: the more it is
pulverised, the more favourable it will be to germination.
Choice must then be made of the finest grain.
CARo11NE.—Is it not considered as advantageous to
change the grain, and not sow that which grew in the
same soil the preceding year?
MRs. B.-It is proper, we have observed, to vary the
nature of the crop; but when, in the course of cropping,
grain is to be re-sown, I believe that it is perfectly imma-
terial whether the seed sown was grown on the same
land or elsewhere.
The seasons for sowing are in spring and in autumn.
It is advisable to be done early in eitherseason, especially
in the latter, in order that germination should take place
before the frost sets in. In the spring the period must
be regulated by the nature of the season and the climate.
The seed may either be sown by the hand or by a drill:
M. De Candolle prefers the latter, as being more exact
and regular in its operation. Care must be taken not to
sow too thickly. When more seed is thrown into the
earth than it can nourish, part of it will perish. But this
is not the only loss; for, before it perishes, it will have
consumed a portion of the nourishment which otherwise
would have gone to the support of the surviving crop, and
which, in consequence of this subtraction, cannot attain
that vigour and perfection which is natural to it when well
supplied with food.
EMILY.—This is very similar to the evil effects of the
excess of population, which you explained to us in your
Lessons on Political Economy, when poor weakly chil-
21
J.36 ON TIME SEED,
dren perish, after having languished a few years, and
consumed the food which would have fallen to the share
of the rest of the community, if these supernumerary
children had not been born.
MRs. B.-The analogy holds perfectly good.
Lucerne has been transplanted to the distance of six
inches from each other; and the plants growing larger,
in consequence of their roots having a wider range for
food, others have been transplanted to the distance of a
foot; and others, again, as far as two feet asunder; and
it was constantly found that the plants grew and flourished,
in proportion as the distance between them increased.
Grains of wheat, sown very thin, have yielded from
twenty to a hundred ears of corn.
EMILY.—There must, however, be a limit to this eco-
nomy of seed.
MRs. B.-No doubt: land is not to be had at pleasure;
but so long as the same extent of soil may be made to
yield a better harvest, by sowing a less quantity of seed,
it is no doubt highly advantageous.
The only exception to this rule is when you aim at
producing long and slender stems. This is the case with
hemp and flax. Comparatively little value is set upon the
seed : the stems, for making linen, are the essential pro-
duce. Those seeds must therefore be sown very thick,
in order that the stems may grow long and upright, and
no space be allowed them to branch out.
The Italian corn, with the straw of which hats are
made, is sown very thick, with the same intention, and
cultivated on a barren rocky soil, in order that a deficien-
cy of nourishment may give the straw that morbid deli-
. and slender form which render the Leghorn hats
SG III.162s
Let us now turn our attention to garden culture.
When seeds are sown from foreign parts, you may form
Some judgment of the degree of temperature and nature
of the soil which they require, by the latitude and eleva-
tion of the spot whence they came. Seeds from tropical
climates should generally be sown in hot-beds, having
ON THE SEED. 237
stone or wooden frames: the latter, being a worse con-
ductor of heat, preserve plants from the cold better than
the former. Experience teaches us that hotbeds are
preferable to hot-houses, both for the germination of the
seed, and the growth of very young plants; and small
hot-houses are preferable to large ones (though of an
equal temperature,) so long as the plants have sufficient
room to grow. Of course, they must not be cramped
and stinted for space; for large plants require extensive
accommodation: but the reason why a confined space is
advantageous to small plants has not hitherto been ascer-
tained. The heat generated by the fermentation of ma-
nure, is also more favourable to germination than the
heat of a stove.
CARoline.—That, I think, is easily accounted for.
The heat of a stove is of a drying nature, while that of
the fermentation of manure is always accompanied by
moisture, which will accelerate the swelling of the seed
and bursting of its coats. And why should not this be
the reason, that a hot-bed is preferable to a hot-house, for
the purpose of raising plants from seed? For the one
is heated by fermentation, the other by a stove.
Mrs. B.—The pots in which they are sown are fre-
quently placed in beds of manure in a hothouse. Besides,
the samo argument holds good with regard to green-
houses: the smaller the house, the better it is calculated
for the culture of small plants. It has been suggested,
that small plants being always placed in the front and
lowest rows of the green-house, and hot air having a ten-
dency to rise, they occupy the coldest strata of air.
In the preparation of hot-beds, the manure of horses is
preferable to that of cows, as it more readily decomposes,
and enters into combination with vegetables. That of
pigeons possesses this quality in such a remarkable de-
gree, that it is dangerous to germination, by precipitating
it too much.
CARoll NE.-The seeds, however, are, I believe, never
sown in manure itself, but in pots of earth which are
sunk in it; the plant, therefore, benefits only by the heat
and the evaporable particles.
238 ON THE SEED.
MRs. B.--That is true. Little or no manure should
be mixed with the earth contained in the pots, in which
germination takes place; for the seed, at that period, far
far from being in want of food, requires to get rid of a
surplus of carbon.
EMILY.—But when the germination of the seed is com-
pleted, and the roots shoot out in search of food, some
provision should be made for them.
Mrs. B.-If the earth contained in the pots consists of
rich garden-mould, it will afford a sufficiency. When
land is manured for grain, the seed derives no advantage
from it: the embryo plant is nourished by the albumen:
and it is not till the roots have acquired some consistence
and vigour that they begin to supply the plant with food
from the soil.
You must observe that it is necessary to cover thc
hole, which is made at the bottom of all garden-pots, with
a small piece of tile ; and it is proper, also, to place a
second piece, of larger dimensions, over the first, in or.
der effectually to prevent the too rapid filtration of water.
Care must be taken to keep the earth light and loose
over seeds which are germinating; for if the soil be cal-
careous in drying, after being watered, a crust frequently
forms on the surface, through which the slender stem
cannot penetrate, and the young plant is thus literally
buried alive. The surface of the mould must, therefore,
be kept scratched or raked, to prevent this crust from
forming; or to pulverise it, if the evil has already taken
lace.
p Shallow wooden boxes are frequently used, instead of
pots, for the purpose of sowing seeds: they have the ad-
vantage of affording them more space.
When plants have so far increased in size as to re-
quire transplantation, they should not be pulled up by the
roots, but the whole clod of earth be carefully shaken
out of the pot at once, and then gently divided into parts,
so as to run no risk of wounding the fibrous extremities
of the roots in separating them from the earth which sur-
rounds them.
EMILY.—I have observed that, in transplanting them,
oN THE CLASSIFICATION or PLANTS. 23.
the gardener uses a pointed instrument to make a hole in
the ground, and afford room for the roots of the young
plant.
MRs. B.-This is exactly the reverse of ploughing: it
makes an opening to receive the young plant, no doubt,
but it is at the expense of the contiguous soil, which is
rendered proportionally more compact. It is true that
the young vegetable, at the period of transplantation,
has acquired some vigour; and a light soil is not so
cssential to it as during germination. It is preferable,
however, to transplant in furrows, when the earth is
turned up with a spade or a hoe, and the roots afterwards
covered by raking the earth over them.
But we are deviating from our subject. Now that we
have fairly traced the seed through the process of germi-
nation, we should conclude our conversation, and reserve
what remarks I have to make on planting, to some future
day.
CONVERSATION XXI.
ON THE CLASSIFICATION OF PLANTS.
EMILY-You have often talked to us of plants belong-
ing to different families, my dear Mrs. B., but you have
never explained the exact meaning of the word family in
the vegetable kingdom; and l wish you would also teach
us how to find out to which family a plant belongs.
Mrs. B.-Your question is much more complicated
than you are aware of; and I know not how to give you
a satisfactory answer without explaining the whole theory
of classification, which will be long, and sometimes,
perhaps, you may find it tedious.
EMILY.—I have no fear of undertaking it; for I am
conscious it is necessary, and that, without such informa.
tion, it would be difficult to remember many things that
you have taught us.
Mrs. B.-You are quite right: the number of natural
21+
240 ON THE CLASSIFICATION OF Pſ,ANTs.
beings is so immense, that without some mode of classi-
fication, it would be impossible to form a correct idea of
them. Would you believe that there are no less than
sixty thousand species of plants already known, and that
this number is increasing every day !
CARolisE.—Oh, Mrs. B., what a host!
MBs. B.-You have named it very justly. Well, then.
to carry on your conſparison of a host, do you conceive
that any general, in reviewing sixty thousand soldiers,
would be capable of recollecting every individual 1
CARoline.-Certainly not; but as each regiment has
its uniform, and each company its number, he could
easily discover to which any soldier belonged.
MRs. B.-This is exactly the object a botanist has in
view in classification. He endeavours to find out to
which regiment and to which company each individual
plant belongs; but this is much more difficult than with
an army, where the general has himself chosen the uni-
forms, and arranged the companies so as to make the
distinctions most conspicuous. Nature has also, it is
true, her distinguishing characters; but they are often
placed in organs which are least exposed to view ; and
botanists do not always agree on the characteristic
features of plants.
CARoline.—Well; but tell us at least on what points
all botanists do agree.
MRs. B.-Willingly. You see yonder in the garden
a bed of carrots; every individual of which belongs to
the same species.
Caroline.—Of course; for I know that the gardener
collected the seed sown in that bed, from one individual
plant last year; so that the carrots must all be descended
from the same parent.
Mrs. B.-Now, then, if you extend your idea to all
the carrots in the world, which do not differ from the
carrots in this bed, more than these differ from each other,
you will understand that they may originally have been
derived from the same plant.
EMILY.—Certainly; and that is what we have said
constituted a species. e
oN the classificatiox of PLANTs. 241
MRs. B.-Well, then, if this idea is clear to you, let
us proceed a step further, and, considering each species as
a unity, compare them with one another. Can you recol.
lect any instance of different species bearing a striking
resemblance to each other ?
CARolisE.—Oh yes; there is the white rose, the
yellow rose, the China rose, and many others, which are
very much alike; and yet the gardener assures me that
the seed of the one will never produce the other.
ExILY.-Red clover, white clover, and yellow clover,
bear also a similar resemblance to each other, though
they are all of different species.
MRs. B.-Your examples are well chosen; for the
most ignorant person could understand them. Species
bearing this analogy, are classed together under the name
of Genera. The resemblance of the different species
composing some of the genera is so striking, that their
affinity cannot be mistaken; while in others it is less
marked, and requires some study to be recognised.
CARoll NE.-Like different children of the same fami-
ly, some of whom are so much alike, that you see at once
they are brothers and sisters ; while in others, the
relationship cannot be traced in their features.
Mas. B.-The word genus is a Latin word, signifying
family: your comparison, therefore, cannot but be accu-
rate; and, by following it up, I think you may acquire an
idea of the whole system of nomenclature. You may
easily conceive, that if there were a separate name for
each of the sixty thousand species of plants, no memory
could retain them; nor could these names point out the
resemblances or differences which exist between the se-
veral species.
ExILY.—Of course ; just as if every individual of a
country had a different surname: it would be impossible
to know, among which of them, any relationship existed.
MRs. B.-I see that you have nearly made out the sim-
ple art of nomenclature. Each genus has a substantive
name; as rose, carrot, clover : to which is added the
epithet of white, black, large, small, to designate each
species; so that, instead of sixty thousand names, five
242 ON THE CLASSIFICATION OF PLANTs.
thousand only are sufficient: to which are added a certain
number of epithets in common use, and understood by
every one.
. . EMILY.—There is, then, really a great analogy between
the nomenclature of plants and that of mankind, for the
names of the genera correspond with our family names,
and those of the species with our Christian names.
Mrs. B.—Very true. It is to the celebrated Linnaeus
that we are indebted for this simple and clear mode of
nomenclature ; and it is one of the circumstances which
has contributed most to facilitate the study of botany.
Since, then, the basis of nomenclature rests on the idea
of genera, you may judge how important it is that this
idea should be clearly understood, and that plants not
possessing the requisite analogy should not be placed in
the same genus.
EMILY.—It would be easy to ascertain this analogy
with regard to the species, by sowing their seeds ; but I
know not what test there is to verify the genus of a plant?
Mrs. B.—No wonder you should be at a loss, for it is a
question which has embarrassed the most celebrated bo-
tanists. There is but one means of forming a clear idea
of genera: it is by placing its distinguishiug characters
in those organs of the plant, which, in the common course
of Nature, are least liable to variation. Now, it has been
observed, that stems and leaves more frequently vary in
their structure than flowers and fruit : botanists have,
therefore, agreed to place the characters of the genera
in the organs of fructification.
EMILY.—But are not flowers of the same species some.
times blue, and sometimes white; sometimes large, and
at others small? How, then, can you establish the cha-
racter of the genera, on circumstances which cannot even
serve to distinguish the species 7
MRs. B.-The difference or resemblance of organs,
must not all be considered as of equal importance, in de-
ciding the genus of the plant. All such as relate to co-
lour, flavour, smell, consistence, and the absolute size of
the organs, must, in classification, be set aside ; and those
only which are connected with the symmetry of the
oN THE CLAssification of PLANTs. 243
flower or fruit, the number of parts, their shape, and re-
Hative size, are to be attended to.
CARoline.—Why do you consider the relative size of
organs of more importance than their absolute size 1
EMILY.—That appears to me quite clear. If a plant
grows in a rich soil, all its parts will be larger than a simi.
lar plant growing in a meagre soil; yet the plants will be
of the same nature. But if the stamens of a plant be
twice as long as its petals, it will certainly be of a differ.
ent nature from a plant of which the stamens are shorter
than the petals; and, were the two plants well or ill fed,
their proportion or relative size would not be altered.
CARolin E.-You say, Mrs. B., that the number of or-
gans of a plant is admitted as one of the characters of
genera; but I think, I remember having seen, on the
same syringa shrub, flowers, some of which had four,
and others five petals.
MRs. B.—Your observation is correct; and, in order
to obviate this difficulty, you must be guided by the same
rule, in regard to number, which Emily has just pointed
out with regard to size. Thus, for example, the pink has
twice as many stamens as petals: this character never
varies, unless in some peculiar cases of monstrosity, which
derange the whole economy of the plant.
With regard to the absolute number of organs, that is
to say, whether a plant has four or five petals, eight or ten
stamens, is a circumstance attended with much more un-
certainty; it may, however, be used as a character in
classification, provided it be done with caution, and in
cases only, in which experience has shown, that the varia-
tions are inconsiderable. Botanists know, for instance,
that the greater the number of organs, the more liable
that number is to vary. This is a law which prevails
throughout all Nature.
Emily.—It is evident that the number of our fingers
varies less than that of our teeth, and the latter less than
that of our hair.
Mrs. B-These general rules will, I hope, make you
understand how botanists have been enabled, gradually
to draw a more accurate line of demarcation in circums
244 ON THE CLASSIFICATION OF PLANTS.
scribing the genera of plants, aud determining their cha-
racters. This constitutes one of the most essential
branches of botany; for it is certain, that the better the
structure of plants is known, the more easily new plants
are discovered, because we are enabled to ascertain their
characters, and, consequently, to class them with greater
precision; and thus the art is gradually brought to some
degree of perfection.
EMILY.—But since the nomenclature is founded upon
genera, if you change the genera you must change also
the names of plants, which is very perplexing for begin-
Il CIS,
MRS. B.-That is true; but it would be a source of still
greater perplexity to allow a plant to remain in a genus,
in which, through ignorance, it had been erroneously pla-
ced, and of which it had not the characters, for you would
never be able to recognise it. Let us suppose, for in-
stance, that the pear tree had been placed in a genus, the
distinguishing character of which, is to have six petals :
as it has only five, you would never think of searching
for it in a genus of six petals. Would you, then, disap.
prove of its being transferred to the genus whose charac.
ter is to have five petals?
ExIILy.—No, certainly; but such errors seem to me to
be impossible.
MBs. B.-Not so much so as you imagine, owing to the
number of the organs frequently differing in the same
plants, like the petals of your syringa. Besides, foreign
plants are often described in a hurried manner by incom.
petent botanists, and are sometimes brought to Europe in
such an imperfect state of preservation as to afford very
bad specimens. You see, therefore, that in this case, as
well as in many others, truth must be preferred to simple
convenience.
CARoline.—But, my dear Mrs. B., you have not yet
said one word of the families of plants, which you had
promised to explain to us.
MRs. B.-A little patience, my dear. I cannot tell you
every thing at once ; and I like to begin by the beginning.
I have explained to you how all individual plants, resem-
ON ARTIFICIAL SYSTEMs, ETC. 245
bling each other, form a species; and how, by following
up the same idea, and uniting in your mind all the species
whose flowers and fruits are nearly similar, you form a
genus. When you have accomplished this, procecd a
step further: consider the genus as a unity; and we will
then endeavour to make out how the five thousand genera
of the vegetable kingdom can be so arranged as to be
most easily recognised. But first tell me what is your
particular aim in studying botany?
CARoLINE.-I wish to be able to find out the name of
any plant I may chance to meet with.
EMILY.—I confess, for my part, that I am not very
anxious about the name; but I should like to understand
the structure of any plant I see, and how far it coincides
with or differs from other plants.
Mrs. B.-You have each answered as I expected.
Caroline, who is the youngest, and the most volatile, is
satisfied with inquiring after names. Emily, who is older,
and more considerate, seeks after things. Well, my
dears, the learned world have done like you. In the in-
fancy of botany, they sought after names: when further
advanced, they aimed at learning the essence of things.
I shall follow their steps, and first explain to Caroline, by
mere nomenclature, how to find out the name of a plant;
and then teach Emily, what has been called, the natural
method. But I think you must be tired to-day: we will,
therefore, defer it till our next interview. In the mean
time, reflect upon the subject; and let me know, when
we meet, which you think may be the best means of at-
taining the object which you each have in view.
CONVERSATION XXII.
ON ARTIFICIAL SYSTEMS OF CLASSIFICATION OF
PLANTS.
Mrs. B.—I have promised to explain to you to-day, Ca-
roline, how to discover the name of a plant. But why
should you not inquire of some botanist the names of the
246 ON ARTIFICIAL SYSTEMS
plants you may wish to know, and then fix them by rote
in your memory.
CARo11NE.—Oh, Mrs. B., you think me still more
childish than I really am. In the first place, is it proba-
ble that I should always meet with a person capable of
telling me the name of a plant? . And, then, I should be
liable to be imposed upon and misinformed. No ; what
I desire is to be enabled to find out the names of plants
myself—with the assistance of books, I mean.
MRs. B.—It would be necessary for this purpose to
have a dictionary arranged the very reverse of those com-
monly used. Instead of giving the word, and then the
definition, as dictionaries usually do, you must begin by
learning the characters of plants, and then come to the
Ildſ 18,
CARoline.—But a dictionary of this description would
be but of little use to me; for, as I am completely igno-
rant of the characters of most plants, I should not know
where to seek for them in the dictionary. Indeed, my
principal reason for wishing to know their names is to be
able afterwards to learn their history, and become ac-
quainted with their uses and properties.
MRs. B.-I see that Caroline is coming round to your
opinion, Emily; she proceeds from names to things.
This shows me that you have reflected upon the subject,
since our last interview. Various modes have been re-
sorted to, with a view of composing the peculiar species
of dictionary to which I have alluded; and, in order to
give you some idea of them, tell me, have you ever
played at a game called Four-and-twenty-Questions f
CARoline-Oh, yes; I am quite an adept at it. One
of the party thinks of a word or a thing, and the others
try to discover it, in a series of twenty-four questions.
MRs. B.-In this game, the art consists in so skilfully
pointing the questions, that each reply shall contract the
field of inquiry, till it is at length brought within so small
a compass, that the object thought of is attained.
EMILY.—It is like the Indian mode of entrapping ele
phants. They are surrounded by horsemen, who at first
OF CLASSIFICATION OF PLANTS, 2.47
enclose a large space of ground, but, gradually narrow-
ing the circle, drive them gently towards the centre, where
they have no resource but to run into the trap, which is
there open to them.
MRs. B.-Well, botanical momenclature is very much
the same thing. Indeed, the analytical method—the
simplest hitherto used—is exactly similar to the game of
Four-and-twenty Questions. It was first introduced by
M. De Lamarck, and forms the basis of a work he pub-
lished, with M. De Candolle, called the Flore Françoise.
Here is a plant in blossom in this flower-pot: I know
that it grows wild in the south of France. I shall ask
you a few questions relative to it, according to the method
followed in the Flore Françoise, and you will see that you
will soon discover the name of the plant yourself.
CARoline.-Oh, that will be very amusing.
Mrs. B.-First, then, tell-me whether the flowers are
visible to the naked eye, or whether they require to be
seen through a microscope 1
CARol.INE.-The plant is quite covered with them, and
they are perfectly visible; for you may see them from
Some distance.
Mrs. B.-Are the flowers united by an involucrum or
not ?
CARoll NE.-No ; they have no involucrum.
Mrs. B.-Have the flowers both pistils and stamens, or
only one of these organs?
CAROLINE.—They have both.
MRs. B.-Have the flowers both a corolla and a calyx'
CARo11NE.—Yes; they have both.
MRs. B.-Is the corolla of one entire piece, or com-
posed of several parts?
CARolin E.-It consists of several parts.
MRs. B.-In this case, I must refer to No. 211 of the
Flore Françoise; and pray tell me, does the ovary adhere
to the calyx or not ?
CARoll NE.-It adheres to the calyx, and is consequent-
ly situated below the real,
248 ON ARTIFICIAL SYSTEMS
Mrs. B.-Are there several ovaries?
CARolin E.-No; only one.
Mrs. B.-Is the flower regular or irregular !
CAROLINE.-Regular.
MRs. B.-Are there more or less than twenty stamens?
CARoline.—There are, certainly, more than ten; and
I should think about twenty.
MRs. B.-Is the calyx divided into more than two lobes?
CARolin E.—Yes; into five.
MRs. B.-Are the leaves opposite or alternate 1
CARoLINE.-They are opposite, and placed very regu-
larly on the stem.
Mrs. B.-Is your plant herbaceous, or is it a shrub 2
CARoline.—A shrub.
MRs. B.—Is the fruit dry or fleshy?
CARoline.—Let me see if I can find any : there is
very little fruit; but it appears to me fleshy.
MRs. B.-Is that part of the calyx which crowns the
fruit, membranaceous or coriaceous?
CARoline.—It is membranaceous.
MRs. B.-Well, then, your plant must be a myrtle.
Were there several species of myrtle growing in France,
by continuing a similar series of questions, I should soon
discover the species; but as there is only one, (which is
the common myrtle,) I am already fully answered.
CARolin E.-What a simple and ingenious method :
You would easily have won the game of Four-and-twenty
Questions; for you have asked only thirteen. This mode
of analysis must, I suppose, be in very general use.
MRs. B.-It has been much used in France, but very
little in England; nor do I know any English work on
botany arranged according to this method.
CARo1.1NE.—I am surprised at that. Is there any
thing to be objected to it?
Mrs. B.-It has been thought long and tedious; and,
to one no longer a novice in botany, it is tiresome to have
always to recommence and follow up the same routine of
OF CLASSIFICATION OF PLANTS. 249
questions; besides, the slightest inattention, or the least
mistake in the printed numbers, is sufficient to put you
quite out. Then, after all, when you have succeeded in
discovering the name of a plant, it is not very easy to
remember the characters which enabled you to find it out.
Notwithstanding these objections, which certainly have
their weight, I cannot but think this method the best for
beginners.
CARolisE.—Still, if it is not used in England, it would
not be of much use to us. Pray, what mode of nomen-
clature is adopted by English botanists?
Mrs. B.-That which we owe to Linnaeus, which I
have here, and will show you.
EMILY.—Pray do ; for the name of Linnaeus is so
celebrated, that any method invented by him cannot but
be interesting.
Mrs. B.-You are right. A method derived from a
man so eminent in science, and which has been adopted
by so many other scientific men, well deserves our atten-
tion. IIere is a table of the different classes into which
Linnaeus divided the vegetable kingdom.
250
ON ARTIFICIAL SYSTEMS
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Or three in-
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1 Monandria
2 Diandria.
3 Triandria.
4 Tetrandria.
5 Pentandria
6 Hexandria.
7 Heptandria.
8 Octandria.
9 Enneandria.
10 Decandria.
11 Dodecandria
12 Icosandria.
13 Polyandria.
14 Didynamia.
15 Tetradynamia
16 Monadelphia
17 Diadelphia
18 Polyadelphia
19 Syngenesia
20 Gynandria.
21 Monoecia
22 Dioecid
23 Polygamia
24 Cryptogamia
OF CLASSIFICATION OF PLANTS, 251
CAROLINE.-It appears very complicated.
MRs. B.-It is less so than you imagine. This systein
of Linnaeus forms precisely an analytical table. Return
to your myrtle, and let us follow it.—Stamens visible to
the naked eye, in the same flower as the pistils, but not
united to them; all of the same size; about twenty in
number; growing from the calyx; the myrtle belongs to
the class Icosandria of Linnaeus.
CAROLINE.—And then what follows?
MRs. B.-These classes are divided into orders, which
depend principally on the number of styles.
CAROLINE.-The myrtle has only one style.
Mrs. B.-Therefore it belongs to the order Icosandria
Monogynia. Here is an edition of Linnaeus, published
by Willdenow. You see that the above order contains
twenty-two genera : you must therefore examine the
characters of each genus, and you will soon find out those
which correspond with the myrtle.
EMILY.—This method, certainly, must be much more
complicated than the other.
MRs. B.-It may appear so to a beginner; but you
would soon become used to it; and I assure you that it is a
very convenient mode of discovering the names of plants :
at least, of those, which do not belong to a class contain-
ing a very great number of genera; such, for instance,
as those of Pentandria and Syngenesia, which contain
from four to five hundred each. But, even in these
cases, practice and habit soon render familiar a system
which at first sight appears perplexing and difficult.
EMILY.—How often have I made that observation
When I first began learning the piano-forte, I shall ne-
ver forget the difficulty I had to distinguish the different
notes; whilst now I play without even thinking of them.
But, Mrs. B., the system of Linnaeus rests almost entirely
on the number of the different organs of plants; and we
have observed more than once, that number is a charac.
ter which can be little relied on in botany. Yesterday
we mentioned the irregular number of petals of the Sy-
ringa; and this morning I observed a plant of rue which
22*
252 ON ARTIFICIAL SYSTEMS
bore in the same cluster flowers, some of which had
eight, and others ten stamens. Does it belong to the
eighth or the tenth class 1 I am sure I deserve to know,
were it only to make up for the disagreeable smell I had
to encounter in examining it. *
Mrs. B.-In cases of this sort, botanists have agreed
to class the plant according to the first flower which
blows in the cluster; and, following this rule, the rue
belongs to the tenth class. But what is still more em-
barrrassing is, that the number of stamens often vary in
an irregular manner. Thus you may meet with tulips,
and several other plants bearing indifferently five, six,
seven, or eight stamens. In this case you must class
them according to the number most usually found.
Several other sources of error occur in the system of
Linnaeus. For instance, there are many plants in which
the inequality of the stamens, and their adherence, is so
difficult to distinguish, that it is not easy to know to what
class they should be referred. There are also Diaecious or
Monaecious plants, which are become so by mere acci.
dent; and which you would seek for in vain under the
head Diaccia or Monarcia.
The class Polygamia is also one of those which can
scarcely be made out by a beginner. Notwithstanding
the imperfections of the Linnaean system, it is one of the
most convenient; and, even were it less so, it would be
necessary, in order to make any proficiency in botany,
to be well acquainted with it, as it is that which is most
generally used in botanical works.
EMILY.—But, in small flowers, does not the extreme
minuteness of the organ which it is necessary to investi-
gate, render the system of Linnaeus liable to error?
MRs. B.-True ; this is one of the sources of error
which even the genius of Linnaeus could not overcome.
EMILY.—When two plants have each an organ per-
fectly similar, is it a necessary consequence that they
should resemble each other in other respects
MRs. B.--Sometimes, but not always. Thus, in this
system of Linnaeus, the class Tetradynamia contains
plants all having a certain natural resemblance; the same
OF CLASSIFICATION OF PHANTS. 25.3
may be said of the class Syngenesia; but in the other
classes they frequently differ considerably.
EMILY.—This is not very logical, I think
MRs. B.-It is true that it would not be so, had Lin.
naeus meant that his system should point out the real dif.
ferences of plants. But his intention was merely that it
should answer the purpose of a dictionary, by means of
which it would be easy to discover the names of plants;
and, in this point of view, it may fairly be affirmed, that
the greater the number of points of difference existing
between plants, belonging to the same class, the easier
it is to discover the name of each.
The followers of Linnaeus have unfortunately not al.
ways well understood his intention of thus supplying bo-
tanists with a mere nomenclature, or, as it has been call-
ed, an Artificial System ; and the habit of studying the
pistils and stamens has made them attach too great im-
portence to these organs of fructification, while they have
neglected the fruit and the seed. They have also, in gen-
eral paid too much attention to the number of the organs,
and not sufficiently considered their relation to each oth-
er; so that, if they have rendered it an easy thing to dis-
cover the name of a plant, they have not advanced the
science of botany so much as they would have done had
they directed their researches more to the general pro-
perties of plants.
Exily.—The system of Linnaeus might, I think, be
compared to a dictionary, which, though you learnt all
the words it contained by heart, you would still be igno-
rant of the language, unless you added to it a knowledge
of the grammar which teaches the value of the relative
terms.
Mrs. B.-Well ; that arrangement, which is called
the Natural System, teaches you the grammar. But in
reply to your observation, I might retort that a grammar
alone is not sufficient to make you acquainted with a lan-
guage—a dictionary is also necessary, in order to look
out for the words; you must not therefore undervalue
botanical dictionaries, which facilitate the study of no-
menclature : yet always bear in mind that they teach
only the names of plants; and that, if you wish at the
254 ON THIE NATURAL SYSTEM
same time to acquire a general knowleege of their strue.
ture, you must study the naturgl system.
Exſily.—That is what I am most anxious to do : pray
give us some general idea of it.
MRs. B.-With pleasure ; but not to-day: we shall
examine it when next we meet. In the mean time re-
flect upon the subject, and endeavour, of your own ac-
cord, to discover some mode of classing plants which
would most easily show their true analogy.
CARo1.1NE.—I will think of it; but it appears to me a
very difficult task.
CONVERSATION XXIII.
ON THE NATURAL SYSTEM OF CLASSIFICATION.
Mrs. B.-WELL, my dear, have you been able to dis-
cover any mode of classing plants, according to the ana-
logy they bear to one another ?
CARoline.—I have endeavoured to class the plants in
our garden according to this method. I began by com-
paring them all together, and then divided them into
groups, according as they more or less resembled each
other.
MRs. B.-I should have no fault to find with your
mode of proceeding, if the whole vegetable kingdom con-
tained, like your garden, only a small number of plants.
This mode was, in fact, the first employed, and was called
the Méthode de Totonnement. Even now it is occasion-
ally employed by botanists, as a guide in their researches.
But you will easily understand, that, independently of the
impossibility of being put in practice, since the number
of plants known has so much increased, it has also the
great defect of depending merely upon opinion, and aſ:
fording no certainty of the reality of the resemblance
assigned to different plants. It is much the same as with
likenesses of different persons: how often people vary in
opinion in regard to such resemblances !
OF CLASSIFICATION. 255
CARoline.—So much so, that, while many people de-
clare that I am the very picture of my father, others see
no resemblance whatever between us.
Mrs. B.-The same diversity of opinion would take
place in natural history, had not botanists laid down cer-
tain precise rules for judging of the external characters
of plants; and, Emily, have you no new mode of classifi-
cation to suggest ?
EMILY.—If I tell you one that has occurred to me, I
fear you will think me very presumptuous.
Mrs. B.-By no means, my dear : on the contrary,
nothing is more gratifying to me, than to see that you are
capable of reflection, whatever may be the object.
EMILY.—We examined yesterday the system of classi-
fication founded upon a single organ: well, if I had to
class the vegetable kingdom, and was well acquainted
with the structure of plants, I should make as many dif.
ferent arrangements as there are different organs. The
first, for instance, would be made after the roots, the next
after the stems, the following after the leaves, another rela-
ting to their position, another according to the number of
the organs, and so on. I should thus form, perhaps, a
hundred different systems. Now, I suppose that the plants
which were placed together in ninety-nine of these sys-
tems would bear the strongest possible resemblance to
each other; in ninety-eight, a little less so : in a word,
that the resemblance between plants could be asertained
by the number of systems common to each.
MRs. B.-Your idea is very ingenious, my dear Emily;
and, though I do not agree with you in opinion, you may
boast of having suggested the same theory as a very dis-
tinguished French botanist, M. Adamson. He called it.
“Method of General Comparison,” and bestowed much
labour upon it; but, as he lived so long ago, as the year
1760, he was far from being acquainted with all the dif.
ferent characters of plants, which rendered his system
very incomplete. Even in our time, though great pro-
gress has been made in botany, new characters and pro-
perties are frequently discovered in plants; consequently,
a classification of this description would still be incom-
plete.
256 ON THE NATURAL SYSTEM
ExIILY.—I own that objection did not occur to me, be.
cause I thought that the degree of precision in any mode
of classification depended upon the state of the science at
the time it was made.
MRs. B.-There is another objection, of still greater
weight. According to your system, you count the num-
ber of organs that resemble each other, in different plants,
but you make no estimate of the relative importance of
each; yet you must consider that all the organs are far
from being of equal importance. Plants which resemble
each other in a few of their principal organs, have more
real analogy than those which are similar in a great many
minor points. You may easily conceive that plants whose
seeds are alike, resemble each other infinitely more than
those which shoot out thorns of the same nature. For
the seed may be considered as the miniature of the plant,
from the development of which all the growth of it must
arise ; while the thorn is a mere accidental generation.
which may or may not take place.
EMILY.—This objection is certainly of great weight,
and I am afraid that I must abandon my system; but is it
possible to appreciate the relative importance of the dif.
ferent organs?
MRs. B.--To a certain extent, at least. The method
of classification, grounded on this principle, is called
“Method of Subordination of Characters.” It was first
suggested by Bernard Jussieu.
EMILY.—How much I should like to read his works on
this subject :
MRs. B.-He never published anything : like Socro-
tes, he taught in conversation. His nephew, M. Antoine
Laurent De Jessieu, who is still living, published, in 1789,
the results of his uncle's theory. In 1823, M. De Can-
dolle published a work, in which the principles of this
mode of classification are fully developed: they are pro-
bably the same as those of M. De Jussieu, since his de-
ductions from them are similar to those of his predecessor.
CARoline.—Then M. De Candolle must be the Plato
of this modern Socrates ?
Mrs. B.-Or even something more; for Plato, I be
OF CLASSIFICATION. 25?
lieve, wrote only what Socrates had taught ; but M. De
Candolle brought to light those principles from which M.
Bernard Jussieu had drawn his deductions.
EMILY.—It is a curious thing in science, for the
founder of a new school not to publish his opinions.
But, pray, what are these principles They must, I
think, be very difficult.
MRs. B.-We have agreed that all the organs of plants
are not of equal importance: now there are three modes
of ascertaining the degree of consequence of each. The
first is its utility: this is the most general, and would be
sufficient of itself, were we so perfectly acquainted with
vegetable physiology, as to judge of the importance of an
organ, by its degree of utility in the economy of a plant
Thus we may safely conclude, that an organ essential to
the life of a plant, is of a higher order than one of which
it can be deprived, without sustaining any material injury.
EMILY.—But are the functions of different organs not
sufficiently known, tº enable us to judge whether they are
more or less essential to a plant?
Mrs. B.—Not always; but in a doubtful case, there
are two other rules hy which you may be guided. Gene.
rally speaking, the greater the number of plants in which
the same organ can be found, the greater is the degree
of importance that ought to be attached to them. For
instance, the calyx may be pronounced to be an organ of
much greater consequence than the involucrum, because
a greater number of plants have a calyx than an involu-
4°ruline
ExIILy—I understand that perfectly.
MRs. B.-There is besides a third criterion. There
are certain organs which exist, or which are wanting in
all the plants of the same family; and others that are
only occasionally found in plants, otherwise very similar
to ach other. The first of these organs are naturally of
much greater importance than the latter, as they appear
to be indispensable to the system of organisation of these
plants. Were you to ask me, for example, whether a
stipula or a thorn were of greatest importance, I should
258 ON THE NATURAL SYSTEM
not hesitate to say the stipula, for the reason I have just
assigned.
EMILY.—When you judge of the importance of an
organ by its degree of utility in the economy of a plant,
how can you compare organs adapted to functions of a
completely different nature? In the animal frame, it
would be difficult to determine whether the lungs were a
more useful organ than the stomach, the eye than the
hand—does not the same difficulty occur in the vegetable
structure ?
MRs. B.-Your observation is perfectly just; and, in
fact, botanists can only, with any degree of certainty,
compare such organs as are adapted to the same class of
functions. For instance, you will readily admit that the
brain is of higher rank than any single nerve, and the
heart superior to any other blood-vessel; but if you in-
quired whether the heart or the brain were of greatest
importance, it would be quite out of my power to answer
you. If you will promise not to laugh at me, I will ven-
ture upon a very trivial comparison.
CAROLINE.-Pray let us hear it, Mrs. B. ; I am so
fond of comparisons—indeed, I often understand them
better than arguments.
MRs. B.-You are, no doubt, aware that a captain is
of higher rank in the army than a lieutenant, and a colo-
nel than a captain; you know, also, that the governor of
a province is of more elevated dignity than the mayor of
a small town: but, pray, how would you answer, if I
asked you whether a captain or a mayor ranked highest?
You might say, in some particular cases, the one takes
precedence of the other; but that would depend entirely
upon arbitrary decision, and not on the nature of their
functions, which will not admit of comparison. Now, if
you apply this simile to vegetable physiology in which
there are two great classes of functions; one of which
belongs to the re-production, and the other to the nutri-
tion, of plants; you will understand that those organs
alone admit of comparison which belong to the same
class.
EMILY.—Pray, give us some example of this?
OF CLASSIFICATION, 259
MRs. B.-In re-production, for instance, the organ of
most importance is the embryo ; next to that the stamens
and the pistils, which, taken collectively, are no less in-
dispensable than the embryo, for without them it cannot
receive life. Then follow the integuments which protect
the embryo; and next those which guard the pistils and
the stamens; after these come the accessary organs,
such as the nectary. You see that I have already given
five different degrees of importance to the organs of re-
production.
ExIILY.—But must you not also arrange, in a similar
order of gradation, the different points of view under
which a plant may be considered 1
Mrs. B.-No doubt; and, for this purpose, you must
be guided by the rules we used in forming the different
genera. The most important of which consists in care-
fully observing the symmetrical position of the organs in
different plants. The natural method of classification
consists in studying the details of the symmetry of the
organs, in the same manner as mineralogy is founded, on
the regular symmetrical laws of crystallisation.
ExILy.—All this appears to me very ingenious in
theory, but difficult in practice. Supposing that I were
capable of classing the vegetable kingdom according to
this order of different organs; what proof should I have
that I was following the right method 1
MRs. B.-You might afterwards class the vegetable
kingdom according to the organs of nutrition, and you
could then compare the two arrangements. Now, if, in
following two methods, each founded upon a set of dif-
ferent organs, the same plants are to be met with in the
same class, is it not infinitely probable that the mode of
classification you have adopted is the true one —the
unage of what really takes place in Nature ? Thus, the
natural order of botany is that in which you obtain the
same result, whether the vegetable kingdom be classed
according to the organs of re-production, or to those of
nutrition. More importance is usually attached to the
organs of re-production, as being the most numerous and
the most varied; the classification is, therefore, first made
23
260 ON THE NATURAL SYSTEM
with reference to them, and afterwards with reference to
the organs of nutrition: the latter of which serve to ve-
rify the former.
EMILY.—It is like making a proof in arithmetic; but
is not this very difficult to reduce to practice 7
Mas. B.-I do not deny that it is sometimes attended
with difficulty. In botany, as in every other science, no
progress can be made without labour and perseverance:—
much yet remains to be done, but it is gratifying to have
a great end in view: it elevates the mind, and renders the
details of a science interesting. The difficulties that oc-
cur in classification arise, either from our not yet know-
ing all the plants that exist, or from our limited faculties
often preventing our acquiring a competent knowledge,
of the nature and internal structure of their organs.
Time may overcome the former of these difficulties; but
the latter will probably never be completely conquered.
Sometimes, for instance, the organs of plants which
ought to be symmetrical, are not all developed; at others,
they are joined together so that their number cannot be
distinguished:—this we have called soldering. Some.
times they assume unusual form and dimension: this is
called degeneration of the organs. These three causes,
considered either collectively or separately, often deceive
botanists in regard to the real nature of the vegetable
organs, but, by dint of observation, the truth is gradually
brought to light.
EMILY.—We should, no doubt, be incapable of under-
standing in detail the results of the principles you have
explained to us; but cannot you give us some slight idea
of them 1
MRs. B.-I will make the attempt, at least. You may
recollect learning the other day, that genera were com-
posed of those species most nearly resembling each
other. Now, by means of the principles I have just laid
down, it was soon discovered, that in a certain number of
genera the organs of re-production were very analogous:
it was then ascertained, that the organs of nutrition of
these same genera, also bore a striking resemblance to
each other. These genera were then united, as it were,
OF CLASSIFICATION. 261
in a group, and denominated a family. . Thus the five
ºna genera form about two hundred and fifty fami-
leS,
CARolixE.—Families of plants, then, are nothing more
than a numerous collection of genera resembling each
other. But, then, genera, in the sense in which it is here
taken, means not families, as it ought to do, from its Greek
origin, but merely branches of families: is not this liable
to create confusion ?
MRs. B.—I think your remark very just: using the
word in some measure in a different sense from which it
is derived appears to me an imperfection in this mode of
classification.
EMILY.—Families are to genera what genera are to
species; or, to follow up the comparison you made be-
tween plants and the human species, we might say, that
families of plants were like nations of human beings;
and that all these families collectively form the vegetable
kingdom, in the same way as all nations of the earth form
the population of the world.
Mrs. B.-Exactly so; and the families of plants, like
the different nations of the world, have each their pecu-
liar characters and habits. Thus, independently of the
analogy between their organs, plants of the same family
often resemble each other in their mode of life, and in
their peculiar properties. For instance, all the Ficoideae
have succulent leaves, suffer from moisture, and inhabit
climates where the sun's rays are powerful; then, the
Malvaceous family bear leaves of an emollient nature;
the embryo of all the Euphorbiaceae is of an acrid na-
ture ; the roots of the Valerianeae have all a particular
Smt ll, and act in a peculiar manner on the nervous sys-
tem; the Cruciform family is, in all its branches, anti-
scorbutic. In a recent voyage, undertaken with a view
of discovering the spot where the celebrated La Peyrouse
was shipwrecked, the whole of the crew was afflicted
with a scorbutic complaint, which was greatly relieved
by feeding on an unknown plant of the cruciform family
growing on the coast of New Holland—a remedy which
was pointed out to them by the botanist attached to the
262 ON THE NATURAL SYSTEM
expedition. There is another point of resemblance be.
tween plants of the same family, I have before mentioned:
which is, that these alone are susceptible of being grafted
on each other.
CARo1.INE.-These analogies are extremely curious;
and I understand now, perfectly, how much superior your
method is to those which merely indicate the name : for
when I know that a plant has four stamina, it teaches me
nothing further; while the knowledge that a plant be-
longs to such or such a family makes me acquainted, in a
great measure, at least, with its structure and its proper-
tleS.
EMILY.-I am glad, Caroline, that you have come
round to my opinion; for I felt a sort of instinctive con-
viction that it was in analogies of this description that the
interest of the study of Nature consisted. But pray, Mrs.
B., is it not possible to group families together in the
same manner as you have done genera !
MRs. B.—Yes; there is still another step in classifica-
tion, which brings us to the three great distinctions with
which you are already acquainted.
First. That class of vegetables called Dicotyledons,
relative to their organs of re-production; and Eaogenous,
relative to their organs of nutrition. This is by far the
most numerous of the three classes, comprehending about
two-thirds of the vegetable kingdom.
Secondly. The vegetables called Monocotyledons, or
Endogenous, according as you allude to their re-produc-
tive or nutritive organs.
Thirdly. The class called Acotyledons, from being des.
titute of cotyledons, are also called Cellular, because their
nutritive organs have no vascular system. To complete
the comparison we have followed up, these three great
classes may be considered as the three great continents
of the world; the different families of plants as the vari-
ous nations into which these continents are divided ; the
genera represents the families of each nation; and the
species must be considered as the unity of the scale.
This comprehends the whole system of classification,
which every day becomes more extended and more
perfect.
OF CLASSITICATION. 263
EMILY.—Let me see whether I can make out this
genealogical table of plants.
The three grand divisions give birth to 250 families.
These 250 families produced 5000 genera.
And the 5000 genera, 60,000 species.
MRs. B.-The species, in their turn, give rise to races,
varieties, and variations; but we shall not enter upon
these subdivisions at present, as they are the result of an
artificial, rather than of a natural, mode of propagation;
and, indeed, their numbers are both too great and too
variable to be reckoned in a table of classification. There
are, for instance, no less than fifteen hundred varieties of
the vine, and five hundred of the pear-tree: it is true that
other plants do not afford so great a number.
CARoll NE.-If they did, you might almost as well un-
dertake to count the individual plants as to number them.
But do not the number of species also increase by the
discovery of new plants?
MRs. B.-No doubt they do so. Since the death of
Linnaeus, about fifty thousand new species have been
discovered, making, on an average, one thousand species
every year.
The numbers, therefore, which I have given you, are
intended only to enable you to form a general idea of the
present state of the vegetable kingdom; but they cannot
be considered as permanent.
This explanation will, I hope, enable you to understand
the basis of the natural classification, the details of which
can be acquired only by study and practice.
CARo1.1NE.—But how can we study this system, since
the English botanists follow that of Linnaeus 1
Mrs. B.-Generally they do, but not exclusively. We
already possess two excellent English works: the one
called the Flora Scotica, by Mr. Hooker, in which the
plants are classed both according to the system of Lin-
naeus and that of Jussieu; the other, the British Flora,
very recently published by Dr. Lindley, Professor of
Botany in the University of London, in which the plants
are arranged according to the natural method. You may
23+
J64 ON BOTANICAL GEOGRAPHY.
afterwards consult works of a more general description.
which will carry you still further; and, when once you
are accustomed to investigate the affinities of plants, your
eye will enable you to guess, as it were, a great portion
of what remains to be learnt.
EMILY.—If these affinities are so evident to the eyes
of a botanist, whence comes it that they have only been
so recently studied ?
Mrs. B.—Botanists have long been acquainted with
the affinities of plants growing in great numbers in Eu-
rope. Thus, ever since botany has become a science,
the Cruciferous, Gramineous, Umbelliferous families, and
several others, have been distinguished. But those fami.
lies which are dispersed over every quarter of the globe
could not be classed until the analogy of the different
plants had been discovered and studied; and travellers,
ignorant of botany, are incapable of recognising the
affinities of plants they have never studied.
EMILY.—What an interesting study the comparison of
plants of different countries must be
MRs. B.—Undoubtedly it is. This study is called bo.
tanical geography; and, if you wish to acquire some idea
of it, we will make it the subject of our next conversa-
tion.
FMILY.—With the greatest pleasure.
CONVERSATION XXIV .
ON BOTANICAL GEOGRAPHY.
Mrs. B.-At our last interview I promised to give you
some idea of the laws which appear to regulate the dis-
tribution of plants on the surface of the globe.
CARoline.—Yes; this is the study you called Botanical
Geography.
Mas: B.-It is a science of very recent date; indeed.
it is only within the last few years, that it has been culti-
ON BOTANICAL GEOGRAPHY. 265
vated with any degree of success. It is founded entirely
on the distinction made between the habitation and the
station of plants.
CARo1.1NE.—I do not understand what you mean by
this distinction. Are there two modes of indicating the
country of a plant and the spot in which it grows 7
MRs. B.—Precisely so. For instance, when you say
that the tulip-tree grows in America, you point out what,
in botany, is called its habitation; when you say that it
grows in marshy districts, you intimate its station. Thus,
the term habitation relates to the geographical distribution
of plants on the face of the globe, while station denotes
the peculiar localities in which they are generally found.
EMILY.—I understand your meaning perfectly; but I
cannot conceive that any degree of importance can be
attached to this distinction.
MRs. B.-I will explain it. You will readily admit
that the nature of the soil, the aspect, the degree of mois-
ture, &c., is sufficient to account for particular plants
growing in certain spots rather than in others. Their
station is thus explained by physical laws, with which we
are more or less acquainted. The causes of their habi-
tation are, on the contrary, perfectly unknown to us.
Were you, for instance, to find in America (a circum-
stance not at all improbable) a marshy district, perfectly
similar both in regard to temperature, moisture, and the
nature of its soil, to another marshy district in Europe,
the two marshes would be peopled with plants of a very
different description. The cause of this singular phe-
nomenon appears, therefore, to have existed prior to
the actual state of the globe, and is consequently impos-
Sible to explain.
EMILY.—It is true that the tulip-tree, of which you
were just speaking, grows very well when transplanted
to Europe; and I have heard that our walnut-trees thrive
equally well in America: but neither of these trees grow
spontaneously out of their natural country, or, as you
“all it, their habitation.
MRs. B.—Well, then : botanists, after having studied
the surface of the earth under this point of view (as far
266 ON BOTANICAL GEOGRAPHIY .
as their imperfect knowledge of barbarous countries
would admit,) have divided the globe into twenty dis-
tricts, which they named botanical regions. Each of these
regions possesses a vegetation peculiar to itself, plants of
the same species being seldom found growing (naturally
I mean) in different regions.
CARoline.—How are these regions to be distinguished
from each other ?
Mrs. B.-Those whose limits are the most correctly
determined are separated from each other by a vast ex-
panse of sea.
CARo11NE.-Why a vast expanse 7 Would not a nar.
row sea, like the Mediterranean, serve to define the limits
equally well?
MRs. B.-No ; narrow seas do not constitute a limit
to botanical regions. There is scarcely any difference
between plants which grow in the north of France and
those growing in England, or between the plants on the
two opposite shores of the Mediterranean. Nor do islands
in the vicinity of continents constitute a boundary, as they
have generally the same species of vegetation as the
neighbouring continent; while islands situated at a con-
siderable distance from continents have often quite a
different vegetation. For instance, the plants which grow
naturally in St. Helena and the Sandwich Isles, are almost
all different from those of any of the continents.
EMILY.—Then I conclude that large tracts of conti-
ment, also, must differ in the nature of their vegetation.
MRs. B.-It is so in general; but as the old and the
new world approach very near to each other, if they are
not actually united towards the north pole, the plants of
the northern regions are nearly the same in the three
continents; and the further you recede from the pole, the
more distinct the different regions become in regard to
vegetation.
EMILY.—Are there any natural limits which separate
different regions in the same continent
MRs. B.-There are, but they are less defined than
those separated by seas; so that there is a greater mix-
ture of plants in these regions. Their natural limits in
ON BOTANICAL GEOGRAPHY, 267
continents are, for instance, either extensive sandy de-
serts, such as those of Sahara, which separate northern
Africa from Senegal, or chains of high mountains, which
oppose an insuperable barrier to the conveyance of the
seed by natural means; or, again, vast salt-plains, which
prevent the germination of seeds.
ExIILy.—But are there not a variety of means by which
plants may be conveyed from one region to another ?
MRs. B.-No doubt; and that accounts for plants ap-
pertaining to different regions often being found growing
in the same. Rivers, for instance, and high winds, con-
vey seed from one country to another; birds of passage
transport the seed on which they feed; animals carry
them in their woolly or hairy coats; and, finally, man
conveys seeds wherever he goes : sometimes voluntarily,
as corn and potatoes, which he has disseminated all over
the known world; at other times, unintentionally. And
it is owing to this casual transport, that the plants, and
even weeds, of most of our villages have found their way
to America.
CARolise.—Like Robinson Crusoe, when, by shaking
the dust out of a bag, he produced a crop of corn.
MRs. B.—Very true ; but men have even gone further,
and conveyed seeds from one part of the world to an-
other, much against their intention or inclination; such
as the seeds of the wild poppy and corn-flower, which
can never be completely separated from the grains of
COrne
But, independently of these emigrations, it must be
confessed, that there is a small number of similar plants
existing in different regions, without the possibility of ex-
plaining how they could have been conveyed from one
region to another.
CarolisE.—This is quite a new idea to me: I always
thought that a great number of the same plants were to
be found in countries very distant from each other. I
have heard of the American elm, the apricot of St. Do-
mingo, and many other plants bearing the same names,
both in Europe and in America.
Mrs. B-This is owing, in a great degree, to the first
268 ON BOTANICAL GEOGRAPHY,
colonists who settled in America being ignorant of botany,
and giving European names to plants, which; in fact,
were very different from those whose names they as-
sumed.
EMILY.—I suppose they considered it as a sort of tri-
bute paid to their native country; just as they gave the
names of New York and New Holland, to countries very
different from those of Europe.
MRs. B.-Another reason may also be alleged. It
often happens that differrent species of the same genus
inhabit different regions; for instance, the Vaccinium
Macrocarpum, which we call Canadian cranberry, is of a
different species from the Vaccinium Oxycoccus, or En-
glish cranberry, which we eat dressed exactly in the
same way. Thus, also, the oak, the pine, and the maple,
of the United States, are of a different species from those
which bear the same name in Europe.
EMILY.—It appears, then, that there is no sort of con-
nection between the classification of plants and their
geographical distribution.
MRs. B.-Theſe is some slight connection, but it is so
variable that it is little to be depended on. Thus, while
certain families and certain genera are dispersed all over
the world, others are confined to a single region : all the
Cacti, for instance, come from America; the Aurantiaceae
from India or the neighbouring countries; the Epacrideae
from New Holland ; and among the genera there are
many, every species of which inhabit the same region.
Thus, all the Cinchonas are derived from South America;
the Gorterias from the Cape of Good Hope, &c.
It often happens that different genera bear so near a
resemblance to each other, that the various species of the
same genera or families are divided, as it were, between
them. For instance, a portion of the Pelargoniums is
situated at the Cape of Good Hope, while another portion
of the same family grows in Van Dieman's Land. Bota-
mists have of late paid great attention to this subject; but
the results of their researches can be considered only as
temporary, as it will ever be liable to change so long as
unknown plants remain to be investigated.
ON BOTANICAL GEOGRAPHY 269
ExILY.—Cannot you give us some idea of the result
of their researches 1
MRs. B.-It has been calculated, for instance, that in
almost all the botanical regions of the world, one-sixth of
the plants are monocotyledons; and that, in regard to
the other two classes, the number of dicotyledons increases
as you approach the equator, and that of the acotyledons,
on the contrary, as you draw nearer towards the pole.
This rule does not prevail in islands situated at a great
distance from any continent: in these, the proportion of
monocotyledons is greater, and that of the dicotyledons
less, than is usually found in continental regions of the
same latitude.
CARoline.—You do not mean to say that the same
proportion of monocotyledons exist in Europe as in Asia;
in cold northern countries as in tropical climates ? To
judge from the views I have seen in India, the greater
part of the trees are of the family of Palms.
MRs. B.-A few of such magnificent trees make a
great show in a landscape; but recollect that all our corn
and grasses are monocotyledons. The difference be-
tween this class in England and in India consists, not in
the number, but in the size, of the plant. The vigorous
vegetation of tropical climates produces monoeotyledons
of stupendous dimension, while the chilling temperature
of northern regions checks their growth; and if we go be.
yond the gramineous family it is but to produce lilies,
tulips, hyacinths, and other imperfectly developed bul-,
hous roots. It is only in the most southern parts of Europe
that a few straggling palms denote the approach to a more
vigorous region of vegetation.
CAROLINE.-But tropical climates produce corn and
grasses as well as palm-trees.
MRs. B.-True, but in much less quantity; herbace-
ous plants require less heat and more moisture than is to
be met with in such climates. The number of ligneous,
compared to that of the herbaceous plants, universally
increases as you approach the equator.
EMILY.—Does this increase and decrease proceed in a
regular progression from the equator to the poles?
o
270 ON BOTANICAL GEOGRAPHY,
MRs. B.-No: the number of annual plants, for in-
stance, is very considerably greater in temperate than in
either the tropic or frigid zones. The delicate structure
of those plants render them incapable of resisting either
the dry heat of the tropics or the severe cold of the polar
regions.
Extily.—We have also the advantage of the most
beautiful and delicate colours in the vegetation of spring;
while I have heard that, both in the polar and tropical
regions, the spring-leaves are of a much darker and more
sombre colour.
Mrs. B.-Now that you have acquired some idea of
what is meant by a botanical region, let us observe how
the plants are distributed in one of these regions, and why
different plants prefer different localities.
You will easily understand, that every plant, according
to its particular structure requires the concurrence of
many circumstances in order to be brought to perfection.
EMILY.—No doubt. It is evident that the same soil,
or the same degree of heat, light, or moisture, cannot be
cqually good for all plants.
Mrs. B.—When plants shed their seed, it is more or
less dispersed by wind, rain, or other natural agents, and
is finally deposited on a soil which may or may not be fa-
vourable to its germination. Thus, in particular spots, a
sort of struggle takes place among the different species
of vegetables which it produces. The most vigorous
plants, and those best suited to the nature of the soil,
make the greatest progress, and ultimately exclude the
others.
CarolixE.-So that in the vegetable, as well as in the
animal kingdom, the strong oppress the weak, and a con-
test takes place even among flowers, to all appearance
the symbols of peace and harmony.
Mrs. B.-I am sorry to spoil your poetical ideas of ve-
getation; but such is the law of Nature. You will now
understand, that the richer the soil the greater is the num-
ber and variety of plants that can grow in it. Thus, in
tropical climates, the forests are composed of a much
greater variety of trees than in the temperate zone ; and,
on botanical geography. N 271
as you approach towards the polar regions, the number of
different plants gradually diminishes.
EMILY.—It is, perhaps, on this account that in the high-
lands of Scotland we meet with immense tracts where no
plant is to be seen growing but heath or furze.
Mrs. B.-Precisely. These species of plants being of
a hardy nature, and able to live in a soil from which most
other plants are excluded, meet with no competition, and
establish a colony apart from other plants. Such plants
are called by botanists Social, from their habits of living
together in societies.
CAROLINE.-I think they should rather have been call-
ed unsocial, from their excluding plants of a different
species.
MRs. B.-They at least deserve the name of inhospi-
table : the Potamogetons, which grow in stagnant waters,
Kelpwort (Salsola,) and Saltwort (Salicornia,) which
grow in salt districts, are of this description. There are
some plants which become social from their mode of pro-
pagation ; those, for instance, which have spreading
roots, such as the Hieracium Pilosella, or Mouse Ear
Chickweed. Plants, on the contrary, whose seeds are
crowned with a tuft, which enables the wind to have more
power over them, are dispersed to a great distance :
between these two extremes there exists a great variety
of intermediate degrees.
There are some plants which, so far from excluding
those of a different species from their society, seem to
take delight in the neighbourhood of trees to which they
themselves bear no resemblance: thus, the Salicaria
loves to grow at the foot of the willow ; the Monotropa,
at the foot of the pine ; the Sarote, to grow among oats.
EMILY.—What can be the reason of this singular kind
of attachment of one species of plants for another?
MRs. B.-Several has been assigned : first, that plants
of different species frequently require the same soil; the
next (of a more doubtful nature) is, that the exudations of
some plants may promote the growth of others of a dit-
ferent species: a third reason alleged is, that certain
plants often serve to protect others of a different species,
24
272 ON THE INFLUENCE OF CULTURE
as hedges and bushes protect the creeping plants which
grow between their branches.
Extily.—It appears, then, that we can in some degree
explain that prodigious mixture in the vegetable king-
dom, in which at first I thought there was no sort of
order.
Mrs. B.-There is always order in the works of Na.
ture; and what appears to us disorder is the result of dif.
ferent laws acting at the same time. By following the
mode of reasoning I have pointed out to you, and by con-
stantly comparing the structure and the habits of plants
with the nature of the soil in which they grow, a great
number of curious facts may be explained. "I am glad to
have drawn your attention to this subject ; it will be a
source of amusement in your walks : and the greater the
number of plants you become acqainted with, so as to be
enabled clearly to distinguish their different species, the
inore interesting will your observations prove.
CONVERSATION XXV.
ON THE INFLUENCE OF CULTURE ON VEGETATION.
MRs. B.-Let us now examine to what extent the na-
tural state of plants can be modified by the art of man.
For this purpose it will be necessary for me to make you
acquainted with certain differences which exist in plants
of the same species.
A species, you recollect, comprehends all those plants
which bear so great a resemblance to each other that we
may reasonably suppose them to be descended from the
same parent stock. But, independently of this general
similitude, each species admits of various shades of dif.
ference, some of which are strongly marked, and of a
permanent nature; others more slight and evanescent :
hence spring the three modifications of Races, Varieties,
and Wariations. Several races derive their origin from
the same species; and the points in which they differ are
of so decided a character, that they are continued from
ON VEGETATION. 27.5
4 tº
the parent plant to its offspring, or, in other words, when
it is propagated by seed.
Varieties are a subdivision of races; in which the
points of difference are of so slight a character, that they
are continued from one individual to another only when
the plant is propagated by subdivision; that is to say, by
grafting, budding, or layers, but are obliterated when it
is raised by seed.
Variations are the feeblest of all deviations: they ori-
ginate in the peculiar circumstances or situation of the
plant, such as peculiarity of soil, temperature, &c., and
are susceptible of being continued to successive individu-
als only if placed under similar circumstances.
Now, the art of man has great influence in varying and
multiplying these several modifications of species. If, for
instance, the pollen of the flower of one species be made
to fall on the pistils of another species, one of two things
may happen: either the flower will produce no seed; or,
if it produce seed, the plant which results from it (which
is called a Hybrid) will partake of the form and nature of
the two plants from which it springs; and hybrids very
rarely produce any seed.
CARoLINE.-It is then, I suppose, only performed as a
curious experiment, since the seed is lost, and nothing is
gained in exchange.
Mrs. B.-True ; but the result is very different, if, in
two plants of the same race but of different varieties, the
pollen of one be made to fall on the pistils of the other, ,
the blossom will in general bear fruit, and thus a new
variety will be produced, differing from those from which
it drew its origin. Let us suppose, for instance, that
there were but two varieties of cabbages in nature, the
one spherical, the other spreading : by the intermixture of
the pollen of these two, a third variety would be pro-
duced; and by continuing the process between these three
varieties, ten, twenty, or thirty new ones would result.
But as these varieties bear seed capable of reproduction,
it is, in fact, new races which are formed.
In Belgium, the horticulturists, with the most patient
perseverange, produce, by this process, a great number
of new varieties of fruit trees, which they propagate by
274 ON THE INFLUENCE OF CULTURE
seed, and thus give birth to new races; but this is ex-
tremely tedious, for it is many years before the fruit tree
raised from seed, is capable of bearing fruit.
EMILY.—This period might be accelerated by graft-
ing; but then that process would alter the nature of the
new variety of fruit.
Mrs. B.-Certainly; the Dutch are celebrated for the
beauty, or rather the variety of colour, of the tulips they
have thus introduced. These flowers change their colour
during the first seven years, they afterwards never vary:
this renders a course of experiments, with a view to pro-
duce certain colours permanently, much more tedious,
and, consequently, more expensive than with most other
plants; and the Dutch horticulturists prosecuted their la-
bours with such enterprising zeal, and the passion for
flowers was, in that country, carried to such excess, that
it was thought requisite to enact a law, forbidding the sale
of a tulip for above the sum of four hundred pounds.
EMILY.-Is it possible that any one would go to so great
an expense for a simple flower It is by these means, I
suppose, that many fruits and flowers have of late years
been so much improved. The great variety of beautiful
geraniums and gigantic strawberries are, doubtless, the
result of similar experiments; but the flavour of the fruit
does not, I think, correspond with its size; I even doubt
whether the bulk is not increased at the expense of the
flavour.
MRs. B.-It will seem to be diminished to the palate,
if the same quantity of flavour be diffused over a greater
bulk of fruit; but I believe that the horticulturists consider
that they have improved the flavour, as well as the size of
the fruit.
The influence of culture on variations results from its
influence on the soil, and the quantity and quality of the
nourishment afforded to plants. Hence some parts of a
plant may be made to prosper more than another; the
stem more than the foliage and fruit, if timber be requi-
red; the leaves more than the seed, if grasses; or the
fruit more than the leaves, with most fruit trees. A
change of colour may also be produced. Thus the IIy.
ON VEGETATION. 275
drangia, when first brought from the Isle of Bourbon,
was blue; in this country it is commonly of a pale pink,
and it is the soil principally which has effected this
change; for if cultivated in a ferruginous soil, similar to
that of its native land, the blue colour is reproduced.
Pink flowers may be thus changed to blue or white; but
cannot be made to assume a yellow colour; thus the Hy-
drangia or the Campanul may be varied from pink to blue
or white, but you never see them of a yellow colour.
EMILY.—That is true; Hyacinths are also pink, blue,
or white, but they are seldom of a yellow colour.
MRs. B.-They are the only flowers which form an
exception to the rule, being sometimes yellow.
The neighbourhood of the sea produces a variation in
plants, rendering them more succulent or fleshy.
Grafting also modifies the variations of plants. The
art of pruning has very considerable influence, by modi-
fying the direction of the sap ; but its effect, however
great on the individual plant, produces no change on its
SURCCeSSOrS,
Trees are pruned with a view to improve their beauty,
their health, or their produce. Trees were formerly cut
and trimmed into all kinds of grotesque figures, according
to the tasteful ideas of beauty of our ancestors. Since
this barbarous system has been exploded, that of heading
young trees, in order to thicken the branches and foliage,
has been introduced; but this, we have agreed, injures
the natural port and character of a tree; and all that is
allowed in the present times, in order to improve the ap-
pearance of a tree, is to strip off the lower branches, in
order to prevent its assuming the form of a bush. This
operation should not be performed too soon : the stem,
while young, requires the aid of these lower branches to
carry on the process of vegetation, and supply it with
nourishment: they pour their cambium into the stem at
its base, and thus assist in increasing its vigour.
EMILY.—Yet, would not this operation become dan-
gerous, if long delayed 1 for the larger the lower branches
are suffered to grow, the more serious will be the effect
of their amputation.
24*
276 ON THE INFLUENCE OF CULTURE
MRs. B.-The proper time for lopping them is, when
the tree has attained sufficient vigour to enable it to reco-
ver from the wounds, in the course of the year.
Resinous trees suffer from pruning, by losing too much
of their resinous juices; fir-trees should never be
pruned; but if planted in groups, as we see them grow-
ing naturally, the lower branches, being deprived of light
and air, dry up and perish : it is thus that Nature prunes
them without the infliction of a wound, rom which the
º juices would flow, to the great detriment of the
ant.
P In regard to the pruning, which relates to the health of
plants, not only should all the dead branches be carefully
removed, but the pruning knife must penetrate into the
quick of the wood. It is advisable, also, to cut away all
the parts which are diseased, as these seldom recover,
and would continue, during a few years of sickly ex-
istence, to absorb, uselessly, a portion of the sap, and
very probably, during this period, to communicate their
malady to the contiguous branches.
All branches seriously injured by hail, should be im-
mediately removed; they will then rapidly shoot afresh,
and, in the course of a few weeks, their loss will not be
perceived.
EMILY.—Green-house plants must require a great deal
of pruning, for as their roots cannot grow freely in search
of food, the branches must be diminished, in order to
correspond with their limited quantity of nourishment.
MRs. B.-True ; both root and branch require pruning
annually, when the plants are fresh potted. But observe
that the gardener takes care to atone, as far as lies in his
power, for the contracted sphere in which they vegetate,
by affording them as much food as can be contained in
so limited an extent of soil. sº
Pruning fruit trees is done with the view of either
increasing the quantity, or ameliorating the quality,
of the produce. It consists in retarding the descent of
the cambium, in order that by remaining longer in the
branches, it may nourish them more abundantly. For
this purpose, the branches which grow vertically should
ON WEGETATION. 277
be pruned, because the sap, descending through them
straight downwards, moves with greater velocity than
when it descends obliquely, as it does in lateral branches.
It has sometimes been found advantageous to bend
down the vertical branches, in order that the cambium
should be compelled to rise, in its return from the extre-
mity of the branch ; and the time required to overcome
this difficulty retards its march, and enables the branches
to absorb more nourishment from it, during its passage.
Espaliers are usually trained in the form of a fan, by cut-
ting away the central stem: or the stem may be pre-
served, provided that the branches be trained laterally;
for it is in these, rather than in the stem, that it is essen-
tial to diminish the velocity of the cambium.
You recollect my having already made you acquainted
with three species of buds : those which produce fruit;
those which develope leaves only; and those of a mixed
nature, containing both fruit and leaves.
CARoline.—Yes; and we observed that the more
fruit buds escape the pruning knife, the greater will be
the crop of fruit.
MRs. B.--Care should be taken, however, not to leave
more fruit buds on the tree than the sap will be able
to bring to perfection, else the quality of the fruit will be
deteriorated. Good gardening consists in preserving as
many fruit buds, as the tree can nourish without exhaus-
tion; for if you force a plant to labour beyond its
strength, either the fruit will not ripen, or its size and
flavour will suffer.
CARolix.E.—But this pruning, with a view to improve
the quality of the fruit at the expense of the quantity, is
an unnatural state of vegetation, which, I should suppose,
would eventually be prejudicial to a tree.
Mrs. B.-I cannot consider it so : the finest trees and
the choicest fruit, are those in which art has judiciously
assisted and modified the efforts of Nature. We con.
tribute to the health and general prosperity of the tree
by preventing it from bearing an excess of fruit; and
we make amends for the dimunition of quantity by the
increase of its size and flavour.
278 ON THE DEGENERATION
CONVERSATION XXVI.
()Y THE DEGENERATION AND THE DISFASES OF
PLANTS.
MRs. B.-We shall preface the history of the diseases
of plants by that of the degeneration of their organs,
which often undergo a species of metamorphosis, and,
instead of being developed in the usual manner, degene-
rate into monstrosities.
There are several causes which produce this effect on
plants : 1st. The natural soldering, or cohesion, of the
parts. You frequently see the leaves of branches, the
petals of flowers, and even fruits which unite, forming
double leaves, double flowers, and double fruits.
Such cohesion sometimes regularly occurs. The sin-
gle petal which forms the corolla of many flowers, such
as the convolvulus, is composed of the union of several
others; but as it is not unfolded until after the junction is
completed, we are led to consider it as a single petal :
and such flowers are called in botany monopetalous.

EMILY.—But where this union regulary occurs, it
should, I think, be considered as the natural state of the
plant, and not as a monstrosity. Pray, how does it take
place 2 Is it a species of grafting one petal upon ano-
ther 7
Mrs. B.-No; it is rather a simple adhesion than a
continuity of vessels through which the sap passes.
The petals in which this adhesion so frequently occurs
have no liber; and this, you know, is essential to the
process of grafting, as it is through the vessels of the
liber that the cambium descends.
Another species of monstrosity arises from a want of
vigour in the plant to bring all its parts to maturity.
That which most commonly fails is the seed, which is
produced in such abundance, and requires so much
nourishment to ripen, that the greater part perishes in
the bosom of the flower. The blossom of the horse-ches.
nut, for instance, contains six seeds, enclosed in three
colls; but one only, or at most two, come to maturity.
AND THE DISEASES OF PLANTS, 279
It is the same with the oak; it has six seeds, but only
one acorn is brought to perfection.
CARo11NE.-And to what cause is the want of deve-
lopment owing If the plant be incapable of ripening
so many seeds, why has Nature furnished it with so use-
less an abundance
MRs. B.-The causes of these abortions are probably
numerous; but the principal one is, no doubt, a defi-
ciency of nourishment. Yet so far from inferring that
such failures imply a want of regularity in the laws of
Nature, it is to them that we are indebted for one of the
most efficient means of ascertaining the order which
reigns in the natural world.
A third species of monstrosity results from a degenera-
tion of the organs, which disables them from fulfilling the
purpose for which Nature originally designed them.
Thus, in some plants, the leaves do not sprout, and the
stem, receiving the nourishment which the leaves should
have absorbed, swells out to a considerable size, and ex-
pands like leaves. The Xylophylla and the Caetus
opuntia are constantly in this state. It is said, that the
leaves of these plants bear flowers; but the fact is, they
have no leaves; the flowers grow on the expanded stems.
Flowers having double blossoms are also classed among
the tribe of monsters. This arises from the stamens be-
ing too abundantly nourished. They swell out, flatten,
and are converted into petals; hence the flower becomes
double. Thus we have double roses, double stocks, dou-
ble blossom cherry, &c. The process of this metamor-
phosis is very plainly discernible in the double hyacinth
and the double tulip, where many of the stamens are
completely transformed into petals: others, while expand-
ing for that purpose, still partially retain their original
form. As this metamorphosis never occurs but when the
anthers have perished, it is probable that they are starved
by the stamens absorbing the whole of the nourishment.
EMILY.—It is, I suppose, owing to the destruction of
the anthers, that double flowers bear no seed. But why
should such beautiful productions of Nature be stigma-
tised by the name of monster? It is considering beauty
as a deformity. gº
280 ON THE DEGENERATION
Mrs. B.—However disagreeable are the ideas com-
monly annexed to the term monster, the word simply im-
plies a deviation from the common course of Nature. In
the animal kingdom, such a deviation almost always ex-
cites disgust, and is associated with the idea of ugliness.
Were there consciousness in plants, they might very pos.
sibly consider the unusual quantity of petals and the de-
ficiency of anthers as a deformity; but we, who look
upon a flower merely to delight our sight with its form
and colour, associate the idea of beauty to this unnatural
State.
Another instance of degeneration is, when the petioles
or foot-stalks are transformed into leaves. The Acacia,
for instance, has six or eight pair of leaves, a number
which diminishes every year, till at length the foot-stalk
is wholly deprived of leaves; but receiving all the nou-
rishment which was previously distributed to them, it ex-
pands, flattens, and is itself finally converted into a blade,
resembling a leaf.
EMiſſy.--Though the acacia is not a very common
tree in England, I have seen a great number on the Con.
tinent, but never observed the species of metamorphosis
you describe.
MRs. B.-The acacia to which I allude is that of
Arabia, which produces gum arabic, and is known in Eu-
rope only as a hot-house plant. It is the original and
only true acacia. The tree we cultivate under that name
is derived from North America: it obtained the name of
acacia from some resemblance between its fruit and that
of the Arabian plant, and was distinguished from it by
the title of false acacia : but as the American tree multi-
plied in Europe while that of Arabia was known only to
horticulturists, the epithet false was dropped, and it now
usurps the name which really appertains to the Arabian
plant. Its botanical name is Robinia.
Instead of wholly disappearing, folioles often degene-
rate into tendrils, for want of sufficient nourishment.
The flower-stalk, or peduncle, is also sometimes converted
into tendrils. This occurs constantly in the vine. The
plant at first shoots out abundance of large leaves and
clusters of grapes, when, after a time, the food proves
AND THE DISEASES OF PLANTS, 281
insufficient to support such a profuse vegetation; the new
leaves, gradually unfolded, are of smaller dimensions,
and the cluster of grapes contracted in size. Still nou-
rishment is wanting, and the later shoots, incapable of
developing either flower or leaf, are converted into ten-
drils. Is this an imperfection in the system of vegeta-
tion, or is it not rather a beautiful contrivance, to enable
the plant, when it has sprouted all the branches it can
nourish, to sustain these branches by means of the ten-
drils in which they terminate, and which cling to the first
object capable of affording them support?
EMILY.—These organs, which you call degenerated,
appear to me to serve a purpose no less useful than the
functions they would have performed had they come to a
state of perfection. But do all the various sorts of ten-
drils of climbing plants result from the degeneration of
other organs?
MRs. B.-There is great reason to suppose so. The
most common of these degenerations is the transforma-
tion of the young shoots of branches into thorns. When
a plant shoots more branches than it can nourish, the
most weakly almost wholly cease to grow. The scanty
sustenance they receive serves, however, to harden and
strengthen them: hence the tender extremity is converted
into an indurated sharp point, capable of inflicting wounds,
which you must often have experienced.
CARoLINE.-Is it not singular that these two last de-
generations, resulting from a similar cause, should be so
different in their effects In the thorn the food hardens
without extending the shoot, while in the tendril it is ex-
tended to a considerable length, and is extremely flexible
and slender.
Mrs. B.-Nature has so contrived it, (though by means
which are unknown to us,) no doubt, with a view to pro-
vide support for climbing plants, which are too weak to
bear the weight of their produce ; and where no such as-
sistance is required, she has converted the abortive shoot
into an arm of defence.
Exity.—Would, then, these plants have fewer tendrils
and thorns, if transplanted into a richer soil 7
282 ON THE DEGENERATION
MRs. B.-No doubt; because a greater number of
young shoots would be brought to perfection. M. De
Candolle transplanted a wild medlar-tree, covered with
thorns, into his botanical garden, and in the course of
three years not a single thorn was to be seen upon it.
EMILY.—Yet I have never observed that the rose or
the gooseberry bush lost any of their thorns by cultiva.
tion.
Mrs. B.—They are not thorns, but prickles, which
grow upon the rose, the bramble, the gooseberry, and
many other plants; and these are quite of a different
nature. The prickle is a natural appendage, which has
no connection with the wood; it springs from the bark,
and is peeled off with it; and since it does not result
from the degeneration of any organ, it is not susceptible
of being diminished by cultivation.
The peduncle of the grape terminates in a tendril,
when the vine is loaded with as many clusters of fruit as
it can bring to maturity. But in a very favourable soil,
more grapes would be produced, and this transformation
of the fruit-stalk takes place later, and probably less fre-
quently.
CARolin E.-And may not monstrosity of organs be
produced by plants having too much nourishment 7
MRs. B.-Certainly; it happens, if the nourishment,
instead of being equally disseminated throughout the
plant, partially increases the growth of any particular
part, all disproportion of size among the relative parts, is
a deviation from the regularity of Nature, and must be
considered as deformity; but as it is much more common
for plants to be under than over fed, the monstrocities
which arise from the latter cause are of rare occurrence.
Though these various irregularities and metamorpho-
ses are classed under the head of monstrocities, I am far
from considering them as evils: I view these changes as
advantageous to plants, and if naturalists rank them as
imperfections in the system of vegetation, they are, by
the beneficence of Providence, turned to such good ac-
count, that we cannot but estimate them as blessings.
We shall now proceed to consider the influence of cul-
AND THE DISEASES OF PLANTS, 283
ture on the disease of plants. The botanical physician
must not rest satisfied with studying the symptoms of a
disease, for the same symptoms may be produced by
very opposite causes: thus, plants turn yellow if they re-
ceive either too much or too little water; and, in order
to afford a remedy, the cause of the malady must first bo
carefully investigated.
CARoline.—And that must be very difficult: since, in
examining the patient, you cannot ask him any questions.
MRs. B.-Fortunately, the disease of the vegetable king-
dom are of a less complicated nature than those of animals.
The diseases of plants may be ranged under six differ.
ent heads:-
1. Constitutional diseases.
2. Diseases arising from light, heat, water, air, and
soil, improperly applied.
3. Diseases arising from constitutions and external
injury.
4. Diseases occasioned by the action of animals on
plants.
5. Diseases proceeding from the action of vegetables
On each other.
6. Diseases arising from age.
Variegated or party-coloured leaves, such as those of
the box and the holly, are classed as constitutional dis-
eases. They arise from certain juices of plants, which,
from some unknown cause, change their nature, and
thus affect the colour of the leaf. These changes are
preserved if the plants are multiplied by subdivision,
and even sometimes continued when propagated by seed.
The second class of diseases results from circumstances
connected with the undue supply of elements, which are
in themselves necessary to vegetation ; such as tem.
perature, light, water, air, soil, &c. If a plant has too
much or too little light, heat, or water, it has no means
of avoiding the excess, or of compensating for the de-
ficiency.
CARolisE.—The poor plant, it is true, rooted to the
ground, cannot, like an animal, fly the evil, or seek a reme-
dy; it must patiently submit to it, and endure the dis-
eases it entails: if the soil afford too much nourishment.
25
284 ON THE DEGENERATION
it must continue feeding, and cannot stop when its ap-
petite is palled.
EMILY.—Or, what is worse, and more frequently the
case, when the soil does not yield a sufficiency of nour-
ishment, it cannot seek it elsewhere, and famine must
debilitate the roots, and diminish that vigour which would
enable them to stretch out their fibres over a greater ex-
tent of soil.
MRs. B.—We have already entered so much into de-
tail on the influence of light, heat, water, and soil, on
plants, that I shall confine myself to recalling a few of
the most essential points to your memory. Excess of
light produces too much excitement; the oxygen escapes,
and the carbon is deposited too rapidly; the plant vege-
tates in a ſever, and the sap, incapable of supplying its
wants, is exhausted; the plant withers, and the leaves
fall off. There are two modes of remedying this disease;
either to increase the aliment, or diminish the vegeta-
tion; the first may be done by plentiful watering, the
other by diminishing the intensity of the light.
Excess of heat dries up the juices; if you attempt to
remedy this by plentiful watering, the plant sprouts leaves,
but very little fruit.
CARollnk.-This sort of vegetation must be well
adapted to meadows, where a produce of leaves is prin-
cipally aimed at.
MRs. B.-True ; but plentiful irrigation of leaves is
not always attainable ; where it can be had, no evil effects
need be apprehended from the sun.
A deficiency of heat produces dropsy, and often rot-
ting; the most delicate parts of the plant first begin to
decay, such as the articulations of the branches and of the
leaf-stalks; hence the leaves and young branches fall off.
A plant evaporates much more water than it retains ; it
may be compared to a tube into which you introduce
water : now, it is evident, that the more you pour in at
one end, the more must be poured out at the other: the
evaporation by the leaves must correspond with the ab-
sorption by the roots, else the plant will suffer.
Plants are also often injured by exposure to external
moisture. Rain is more hurtful to the wood than to the
THE DISEASES OF PLANTS. 285
bark; the latter is a sort of great coat, provided by na-
ture to shelter the wood from the inclemencies of the
weather: she has stored it with carbon, to enable it to re-
sist putrefaction; and with siliceous earth, to render it
firm and durable : but if, as it sometimes happens, the
great coat be rent and ragged, the rain penetrates into
the wood (which is very differently organised,) and hav-
ing no means of escaping, the stem becomes rotten.
Exiily.—Among the injuries plants sustain from rain,
we must not forget that of its making the pollen of flow.
ers burst before it is mature, and hence preventing the
seed from being brought to perfection.
Mrs. B.-True; but we have already entered suffi-
ciently into detail on that subject.
In regard to the influence of the air, I have formerly
observed, that the agitation which the wind gives to plants
is advantageous if not carried to excess: the cambium,
being a thick viscous juice, requires motion to promote
its descent.
CARoll NE.—Yet you have said that the great aim of
the gardener is to retard the descent of the cambium, in
order that, by remaining longer stationary in the branches,
it may afford more nourishment to the fruit.
Mrs. B.-That is true, if the production of fruit be the
object aimed at ; but if on the contrary, it be timber, we
must promote the descent of the cambium into the trunk,
instead of endeavouring to detain it in the branches.
Gentle exercise is, however, generally advantageous in
the vegetable economy, and promotes the circulation of
the juices; while violent motion occasions either ex-
haustion or fever. Hence the objection to props and es-
paliers; which we have already noticed. Boisterous
winds are also mechanically injurious to trees, rend-
ing their branches, and sometimes teuring up their roots
from the soil.
Plants are affected by the nature of the atmosphere in
which they grow, There is nothing more prejudicial to
them than smoke.
EMILY.—I am surprised at that: for smoke, you have
told us, consists of small particles of carbon which have
escaped combustion; and carbon, you know, is the fa.
vourite food of plants.
286 ON THE DEGENERATION
Mrs B.-The particles of smoke, though apparently
so small to our senses as scarcely to be distinguished
when separate, are mountains compared to the very
minute subdivision which matter must undergo in order to
enter into the vegetable system. Smoke may clog the
pores of plants, but can never gain admittance through
them.
EMILY.—But smoke is always accompanied by a cur-
rent of hot air, which must be strongly impregnated with
carbonic acid; and in this state the carbon is so minutely
subdivided as to be quite invisible, and I suppose, suffi-
ciently so to enter the pores of plants.
MRs. B.-If plants absorb carbonic acid by their
leaves, or any part exposed to the air, it can be but
in very small quantities. Under common circumstances,
it enters into their system only by their roots; it is their "
leaves which decompose it. Carbonic acid gas is as pre-
judicial to plants externally as it is to animals; for plants
under a receiver containing carbonic acid, die in the
course of a few hours. , Azote and hydrogen do not ap-
pear to be injurious to plants, unless in such quantity as
to diminish the proportion of oxygen in the atmosphere,
which their vegetation requires.
Third class of diseases arises from contusions or other
external injury.
The accidental loss of their leaves, from whatever
cause it may proceed, must be considered as a disease of
plants: if it is not the effect, it is the cause of one ; for
when the sap rises to the branches, and finds no organs
to elaborate its juices, it descends almost in the same
state in which it rose, a thin crude fluid, little adapted to
the nourishment of the stem and branches. Under these
circumstances, its only resource is to feed and develope
young shoots, which nature intended should sprout only
the following year. The sap is then elaborated in the
leaves of the new shoot, is converted into cambium, and
the regular circulation is restored.

EMILY.—How wonderfully prolific Nature is in re-
sources to remedy any accidental interruption to her re-
gular progress One would almost imagine the sap to
be endowed with a sort of instinct, when we find that it is
AND THE DISEASES OF PLANTS, 287
no sooner disappointed in meeting with those organs re-
quisite to its perfection, than abandoning its natural
course, it busies itself in feeding and prematurely forcing
into vegetation the organs which are deficient.
MRs. B.-This admirable fund of resources springs
from an origin far superior to instinct. Its immediate
cause is, it is true, probably either mechanical or chemi-
cal. The sap, for instance, cannot deposit the various
juices required by the different organs, when a deficiency
of leaves, prevents these juices from being secreted. In
its immature state, it is in all probability, better able to
supply the elements required for the vegetation of buds;
and thus the young shoots are prematurely forced into
life. The mere mechanical philosoper will rest satisfied
with this explanation ; but if to the reflecting mind be
added a feeling heart, he will discover that the beneficent
Author of Nature has so admirably regulated the laws by
which it is governed, that they frequently find in them.
selves means of supplying remedies and resources against
accidental contingencies.
CARolisE.—This is, indeed, admirable. In a work of
human mechanism, however ingeniously contrived or skil-
fully executed, constant attention must be paid to watch
and remedy any accidental defect; while the laws of
Nature are of so perfect a description that they are stored
with those remedies which the mechanist is obliged to
supply.
MRS. B.-The loss of bark is so serious an injury as
often to prove fatal to plants. If the evil prevail entirely
around the stem, so as to effect a complete solution of
continuity, the cambium can no longer descend, and the
plant must inevitably perish.
CARo11NE.-But do you forget, Mrs. B., that in cutting
a ring in the bark, to improve the fruit, you perform the
very operation you say is so dangerous?
MRs. B.—This ring, you must recollect, is so narrow,
that the swelling of the upper edge, from the accumula.
tion of sap, soon produces a re-union of the severed parts:
but I was alluding to the destruction of the bark to so
great an extent as to preclude all chance of such a reme-
6) Rººk
**)
288 ON THE DEGENERATION, ETC.
dy. If the bark be only rent on one side of the stem or
branch, it may be considered as a partial infirmity, of
which the plant may recover. For this purpose, the
diseased part should be carefully cut away, and the
wound be covered with an ointment. Let us suppose the
rent to be of a long oval form, as is generally the case;
the cambium, when it reaches this spot, meeting with
obstruction, will accumulate, and produce a swelling on
the upper edge of the wounded part: this will gradually
descend on each edge of the severed bark, till it meets at
the bottom, and the swelling will increase, till the two
sides unite, when the wound will be healed.
EMILY.-I have often observed the swelling of the
bark where a branch has been lopped; but it remains a
protuberant ring around the wound, and does not close,
so that the central part of the wood remains exposed.
MRs. B.-In this instance, not only no ointment has
been used to shelter the part affected, but the wound
being of a circular form, it is more difficult for the edges
of the bark to meet. The young wood, however, which
it is the most essential to shelter, is covered by the swol.
len ring of bark. The flagellations which trees some-
times undergo to bring down the fruit, are injurious to
them, by wounding the young branches; it is so also to
the fruit, unless these be of the nut kind: for apples,
pears, and olives, when thus brought down, are bruised
and very liable to rot.
Plants often suffer from improper pruning. When a
tree is lopped of its branches, they should be cut off ob.
liquely; the sap, when it rises to the wounded part, will
then flow down its slanting surface, while, if the amputa.
tion be made horizontally, not only will the sap be less
able to run off, but the wound will be more exposed to the
rain and wind, and putrefaction will probably ensue.
EMILY.—I have seen the trunks of old willows, the
branches of which are lopped every year, become per-
fectly hollow; which arises, no doubt, from the wood
being thus injured.
Mas. B.-This operation, which is called pollarding a
tree, is done with a view of turning the branches to the
THE DISEASES OF PLANTS, 289
greatest advantage: in willows, generally, for basket-
work; in other trees, for fuel. When a tree is in the
full vigour of life, it will be able to resist such merciless
amputation; but when it becomes aged the wood will not
support it without decaying.
Slight contusions, instead of being prejudicial to plants,
produce an excitement which accelerates vegetation.
The prick or perforation of insects, which we have no-
ticed in the fig-tree, simply occasions a small swelling
somewhat analogous to that produced by a blow given
to an animal: in this swelling a minute quantity of sap
is deposited, which nourishes more abundantly, and,
consequently, developes more rapidly, the surrounding
artS.
p This leads us to the class of diseases arising from the
action of animals on plants. But it is too late to enter
upon it to-day: we shall reserve it for our next inter-
View,
CONVERSATION XXVII.
THE DISEASES OF PLANT'S CONTINUED.
Mrs. B.-Plants suffer much from their leaves being
devoured, either by quadrupeds or insects. The former
not only wound the branches in obtaining the leaves, but,
if the soil be of a loose nature, they disturb the young.
roots; hence pasturage is esteemed injurious in loose and
wet soils. But the insect tribe is a far more insidious and
fatal enemy. Insects not only perforate the plant, in or-
der to deposit their eggs, but, when these eggs are hatch-
ed, the larvae or grubs prey upon the plants which have
afforded them shelter, devouring their leaves, and often
rotting the wood by their acrid juices. Most of these in-
sects bear the name of Cynips: that which produces the
swollen excrescence called gall-nuts, from which ink is
made, is one of the most remarkable. The smoke of to-
bacco and washes made of infusions of that plant are the
best preservatives against these minute but inveterate ene-
290 THE DISEASES OF PLANTS,
mies. The insect called Cochineal fastens itself to the
bark of trees, and sucks the juice through it. The black
spots on orange-trees are insects of this class: they are
Hºlly pernicious in green-houses, and should be brush-
CO. Oile
CARoling.—I thought that cochineal was of a bright
red colour, and that the insect was peculiar to hot climates.
Mrs. B.-The species you refer to comes from Mexico,
and feeds on the Cactus Opuntia, from which it derives the
name of cochineal; but there are many other species of
this insect, which are not confined to tropical climates.
The fifth class of diseases results from the action of
plants on each other. Plants being destined by Nature
to produce a much greater quantity of seed than they can
possibly bring to maturity, we may consider them as con-
stantly struggling with their neighbours to obtain nourish-
ment for their numerous offspring : thus they impoverish
each other, and check that vigour of vegetation, which
would take place, had every plant sufficient space and
food not to interfere with the wants of its neighbours.
EMILY-That is very evident in the superior vegetation
of a single tree, which has ample space for its branches,
and food for its roots, to that of a tree in a crowded forest,
where every inch of ground is disputed by surrounding
plants.
MRs. B.-But, independently of this general compe-
tition for food, there are various other modes by which
some classes of plants are noxious to others. Amon
these the parasitical plants stand pre-eminent. There
are two classes of this description, distinguished by the
epithets of false and true. The false parasite fixes itself
to the plant, without feeding on its juices; while the true
parasite feeds on the plant to which it adheres. . These
two classes are each subdivided into external and internal
* denoting the parts of the plant which they at-
tack.
The false parasites consist of mosses, lichens, and fun-
gi, which grow on living plants just as they would grow on
a rock or a dead tree.
ExILY.-Such as the various mosses which grow on
THE DISEASES OF PLANTS. 291
the stems of fruit trees. But, if they do not feed on the S
tree, whence do they derive their nourishment?
Mrs. B.-From the moisture of the atmosphere, and,
possibly, from the relics of some preceding mosses, which
supply a few particles of vegetable mould.
CARoLINE,-If they do not feed on the juices of the
tree, in what manner do they injure it?
Mrs. B.-Chiefly by attracting moisture to the stem,
and thereby endangering the wood; and also by affording
a lodgment for insects. In these temperate climates,
however, the harm they do is not of a very serious nature;
but, in tropical regions, parasitical plants grow with such
luxuriance (the vanilla, for instance,) that the tree suffers
mechanically from the weight of the mass it has to bear.
EMILY.—I recollect, in the Caschines of Florence,
seeing many of the elm trees so completely covered with
ivy, that I at first sight concluded the tree itself was of
that description.
MRs. B.-Ivy is a creeping plant, not a parasite. Its
roots are planted in, and feed on, the soil : all it requires
of the tree which it embraces, is support. Yet these
plants, as you observe, are frequently prejudicial. I have
seen trees whose branches have been so enveloped, and
strangled, as it were, with creepers, that scarcely any
room was left for its own proper foliage; and the growth
of the tree was considerably impeded.
But to return to our parasites. The Rhizomorpha is a
false internal parasite, which attacks wood; and, though
it does not feed upon its juices, the mere growth of the
plant proves fatal to it, disorganising its parts, and reducing
the wood to a sort of vegetable mould. This malady
seldom occurs but in very aged trees.
EMILy—We, artificial beings, whose aim is to have
plenty of sound timber for building, consider this as a
dreadful malady; but, in the course of nature, it may,
perhaps, simply be a means employed to reduce old or
dead trees, to the state in which they are fitted to return
again into the vegetable system, for this mould must afford
rich food for other vegetables.
MRS. B.-In natural forests, where the hand of man
292 THE DISEASES OF PLANTS,
does not interfere to turn the timber to his own account,
it is certainly desirable that Nature should devise some
means of hastening the decomposition of wood, a sub-
stance so hard and compact that it would require a great
length of time to effect it by the usual process of decay.
In this operation, the Rhizomorpha is aided by a tribe of
insects, which take up their abode in the cracks and cre-
vices, it has made in the wood.
CARoline.—The Mistletºe is, I suppose, a true para-
site; for it derives its nourishment from the tree to which
it is attached.
Mrs. B.-The seed of the mistletoe fastens itself to
the tree by means of a glutinous substance with which it
is covered. The radicle of this seed shoots out in a man-
ner different from that of any other plant: being too
feeble, on its first entrance into life, to penetrate so hard
a soil as wood, it shoots out in some other direction.
CARolise.—It grows, then, in the light and air, which
must be an equally uncongenial soil 1
Mrs. B.-True; and it no sooner makes this discovery,
than it changes its course, and, curving round, retraces
its steps towards the branch whence it sprouted.
CARoline.—Just as if it were conscious that the soil it
had abandoned, was that in which it was destined to grow.
MRs. B.-It is said that it is in order to avoid the light,
that it alters its course; for roots, you know, dread the
light as much as leaves and branches delight in it.
ExIILY.—The dread of the former may, no doubt, be as
mechanically explained as the delight of the latter.
Mrs. B.-Certainly. ... The extremity of the root
having now acquired sufficient strength, as soon as it
comes in contact with the branch, pierces the bark, and
lants itself in the alburnum, whence it sucks up its food,
just as another plant would do from the soil.
CARoline.—With the advantage that its food is already
prepared; it can therefore scarcely require leaves to
convert the sap into cambium.
MRs. B.-I beg your pardon. The soil from which it
feeds is the wood, not the bark; it is therefore the rising,
THE DISEASES OF PLANTS. 29.3
not the descending sap which it receives; the mistletoe
and the tree to which it adheres, may therefore be con-
sidered as the same individual plant. The parasite
receives the sap after the same manner as the branches
of the tree, and, like them, requires leaves for its ela-
boration.
EMILY.—This junction is very analogous to a natural
graft.
Mrs. B.-On the contrary, it is quite the reverse. In
a graft, it is the vessels of the liber which unite; while
the mistletoe strikes its little root through the bark into
the wood, and the junction of the vessels takes place in
the alburnum.
EMILY.—Is it not wonderful that so young and tender
a root should be able not only to pierce the bark, but even
to penetrate the wood 1
MRs. B.--It is, indeed; but observe that it does not
go deeper into the wood than the external layer, which,
being the last formed, is the most tender.
ExIILY.—Then it cannot be so difficult to root out a
mistletoe as I have heard.
MRs. B.-You must recollect, that every year a new
layer of wood grows over the root; so that without
having, itself, penetrated further, it becomes annually
buried deeper; and alter some years’ growth in so hard
and compact a soil that there is but little chance of
being able to extract it, without wounding the branch
beyond recovery, the only mode of effectually extirpating
it, is to cut off the branch to which it is suspended: it is
better to lose that, than to suffer the tree to be molested
by so disagreeable a campanion.
The mistletoe is more partial to some species of trees
than to others; but the oak is the only one almost wholly
exempt from its depredations.
CARolliXE.—I thought that the mistletoe attached itself
to the oak in preference to all other trees, and that the
Druids considered their union as sacred.
MRs. B.-It was probably owing to its so seldon
attacking this tree, that the Druids held it in such high
veneration when they found it there. This tree has,
294 THE DISEASES OF PLANTS,
however, another enemy of a very similar description,
called the Laurientius, which confines its ravages to this
sovereign of the forest.
The Cuscuta, commonly called Dodder, is a parasite,
which attacks lucerne, trefoil, and several of the artificial
grasses: it has neither cotyledons nor leaves, consisting
simply of a sort of filament or stalk, which, after it has
sprouted, falls and perishes when it finds no plant to
which it can adhere; but if it meets with any of the
artificial grasses, it fastens upon them and feeds upon
their juices. The seeds sometimes germinate in the
soil, and sometimes on the artificial grass itself. The
mode of destroying these noxious parasites is either to
burn or to mow the artificial grass very frequently, in
order to prevent the seed of the Cuscuta from germi-
nating; or else to change the course of cropping, and
sow corn; for this parasite will not attack grain, or any
endogenous plant. There are three species of Cuscuta,
one of which attaches itself exclusively to the vine : its
filaments are as large as a small packthread; fortunately
this last is very rare.
The Orobanche is a genus, one species of which ad.
heres to the roots of hemp, and destroys them by devour.
ing their juices.
ungi form a very considerable class of false parasitical
plants; to this class belongs the Erisiphe, which attacks
the leaves of plants: it first makes its appearance under
the form of yellow spots, which afterwards turn black.
There are no less than forty different species of this
parasite.
The Rhizoctonia is a species of fungus, which confines
itself almost wholly to the roots of lucerne and saffron:
this disease manifests itself by the fading of the head of
the plant, and the contagion soon spreads around it, in
rays as from a centre. If one of the affected plants be
pulled up, the roots will be found covered with the noxious
filaments of this fungus: their effects on saffron are so
baneful, that the malady it produces bears the name of
death; and the only way to prevent its spreading is to
bury the affected plants in a sort of cemetery, for it is
necessary to surround them by a ditch; and, in digging
THE DISEASES OF PLANTS, 295
º *
it, care must be taken to throw the earth inwards, to
prevent the contagion from spreading. There are-three
species of this destructive fungus; the brown, the carmine,
and the white : the latter attacks fruit-trees; its filaments
are free from tubercles, while those of the former are
covered with them.
The class of internal fungi is very numerous, there
being not less than three hundred species, each attaching
itself to the plant which suits it. Some of them attack all
the plants of the same family; others confine themselves
to those of the same species. Two of these species of
fungi belong to the rose-tree: they appear at first under
the form of small yellow spots; these increase till they
run into each other; their colour then changes to various
tints of brown and red, tints which you must have ob-
served the leaves of the rose-tree often assume, long
before their natural decay.
CARoline.—This malady, far from disfiguring the
plant, adds to its beauty; but who would ever have
imagined these colours to have proceeded from a sepa.
rate vegetation growing on the leaf 7
MRs. B.-Smut is a fungus, under the form of a black
powder, which lodges itself on the surface of the ears of
corn, particularly of oats. But the most insidious enemy
of grain, of the mushroom tribe, is called the Rot. It
devours the seed, without making its appearance exter.
mally. When the corn is thrashed, the rotten seeds
burst, and the disease is thus communicated to the rest of
the corn; so that if sown, the rot will be propagated as
well as the corn: to prevent which, corn that is at all
affected with this disease, should be soaked in a lime wash.
which destroys the seed of the rot, without injuring that
of the corn.
Mr. Benedict Prevost has found that washes of vitriol
or verdigris, are still more efficacious.
EMILY.—But are they not pernicious to the grain, and
even dangerous to those who employ them?
MRs. B.-It was at first apprehended to be so, but it is
now well ascertained, that neither the labourer nor the
grain suffers from this process: it is much used in France.
296 TIHE DISEASES OF PLANTS.
and even arsenic has been tried with success for this
purpose.
The Ergot is a disease peculiar to rye, which attacks
the ovary of that plant; and bread made of rye thus
affected is extremely unwholesome, frequently producing
gangrene. ſº
It would be endless to detail the various fungi which
molest the vegetable kingdom; we will conclude, there-
fore, with the Rust, which confines its depredations to
the grasses.
It is time now to turn our attention to the last class of
diseases, those resulting from age; and here you must
observe that a very essential difference exists between
the animal and the vegetable creation. In the former, all
the organs are developed at once: these after long use
become indurated, obstructions take place, decay follows,
and life thus often terminates from old age. But the
economy of the vegetable kingdom is totally different :
the organs of the plant, that is to say, the vessels which
convey the juices, the leaves which elaborate them, the
buds which produce flowers and fruit, are renewed every
year; they are always fresh, always young: how then
can a plant decay from age 1
CARo11NE.—I should rather ask why all plants do not,
like annuals, die every year? for these organs which are
renewed in the spring, perish in the autumn.
MRs. B.-Of all the organs which are annually re-
newed in perennial plants, the layer of wood and of bark
alone survive in an active state of vegetation : the others
may be considered as annuals, living but one season.
CARoline.—Then, when a tree dies of age, it is from
the stem being worn out : every year the wood hardens
by the pressure of the new layers which grow around it:
its vessels must, in consequence, become obstructed, and
less adapted to convey the fluids which are to pass through
them : this bears a strong analogy to the decay and
death of animals.
Mrs. B.—True ; but observe that if these vessels are
uo longer calculated to transmit the juices, the plant no
longer requires them to execute this function : it is per-
THE DISEASES OF PLANTS, 297
formed by the fresh layer of wood and of bark which arc
renewed every year: the old repose after their labours,
but do not perish ; age, therefore, does not necessarily
entail death, as in the animal kingdom.
Emily.—From what cause, then, do plants die! for,
though some trees live to a great age, they all ultimately
perish, as well as animals.
Mrs. B.-They are certainly not destined to immor-
tality; but their ceasing to exist seems to depend upon
some accidental disease proving fatal, rather than upon
any prescribed term of years assigned to them by Nature.
The malady which most commonly destroys plants is
exhaustion, arising from their bearing, and ripening, too
great a number of seeds : it is this which regularly,
though not necessarily, occasions the death of animals;
for, if from any accidental circumstance the seeds are not
matured, the plant retains sufficient vigour to live through
another season. Perennials which live several years,
perish ultimately of the same disease.
CARolrxE.—And are there no means of diminishing the
number of seeds of annuals, and by thus preventing ex-
haustion, of transforming them into perennials 7
Mas. B.-This may be done by making the flower
grow double; the additional number of petals are pro-
duced at the expense of the seed; but requiring much less
nourishment, the plant is not exhausted.
EMILY.-But if trees perish only by accidental death,
some at least, should escape; for accidents do not always
OCCUlfe
. Mrs. B.-Not, perhaps, to a certainty in any given pe-
riod ; but in the long course of time, they never fail to
happen; and the extreme inequality in the length of life,
in trees of the same species, affords ground for believing
that its duration depends upon accident.
EMILY.—But some kinds of trees are regularly much
longer-lived than others: the oak, for instance, than the
poplar ; forest than fruit-trees.
MRs. B.-Some plants are naturally much more robust
than others, and therefore resist during a longer period
accidental attacks. The oak, so vigorous and magnifi.
298 THE DISEASES OF PLANTS,
cent a tree, out of six seeds which it produces in every
blossom, brings only one to maturity; and yet with how
much less effort could the oak ripen clusters of acorns
than an orchard tree the heavy load of fruit, under the
weight of which its branches bend; and if any of them
break, how great is the probability that decay will ensue:
the enfeebled vessels of the wood, exhausted by the la-
bour of conveying sap to so much fruit, are unable to re-
sist the consequences of exposure to the weather; and,
after a series of accidents of a similar nature during a
course of years, the tree at last perishes. When, there-
ſore, it is said that such a species of tree, usually lives
such a number of years, the duration refers to the ave-
rage of time in which it falls a sacrifice to accident.
This average it is very difficult to ascertain.
But it is not only ripening seed, which eventually ex-
hausts plants; all the various diseases we have enume-
rated tend to shorten their existence.
EMILY.—Yet those only which attack the wood or
bark can prove dangerous to the life of the tree ; injury
to the other organs, can be of little consequence, since
they naturally perish in the autumn.
MRs. B.-True; but observe that most of the diseases
we have mentioned are of that nature; the parasites
suck up the juices of the stem ; the fungi which adhere
to the stem and branches, those which coil round and
strangle the roots, all eventually injure the wood.
There is in the island of Teneriffe a tree, the Dracaena
Draco, of so remarkable a size, that it served to point out
the limits of possession of different tribes when the island
was first discovered : it has since been repeatedly visited
by different travellers, and during several centuries past
appears to remain unchanged: it may possibly be of so
vigorous a nature as to have existed some thousand years.
CARoline.—And the extraordinary large tree in the
Cape Verde islands, Mrs. B., in which Mr. Adamson
discovered an inscription buried under three hundred
layers of wood must have been of a very great age.
Mrs. B.—From its dimensions and appearance, he
calculated that it was probably about five thousand years
old.
ON THE CULTIVATION OF TREES. 299
CAROLINE.-Even allowing for an error of a thousand
years or two in his calculation, the tree would still be of
a very venerable age.
And without going so far for an example, in Blenheim
Park there are still in existence old trunks of trees, which
are said to have shaded the retreat of the fair Rosamond;
and they are supposed to be now not less than a thousand
years of age.
CONVERSATION XXVIII.
ON THE CULTIVATION OF TREES.
Mrs. B.-Nature has divided the surface of the earth
into meadows and forests: in some parts of the globe,
these are so happily blended as to form the most beauti-
ful variety of prospect; but in general, where the hand
of man has not interfered, they are divided into immense
masses of wood and pasture, which render the appearance
of the country monotonous and melancholy.
EMILY.—I should have thought that, in the course of a
series of years, these different species of vegetation would
have intermixed, so that the seeds of the forest-trees
would have sown themselves and grown up among the
grass, while the latter, on the other hand, would have
spread among the trees and gained ground upon the
forest.
MRs. B.-On the contrary, these two species of vege-
tation reciprocally interfere with each other, so as to pre-
vent either from encroaching on their established limits;
for grass will not grow under the impenetrable shade of
a forest, nor will the seeds of trees germinate in those
thick and rich wild pastures called Steppes, where the
grass rises to six or eight feet in height.
In tropical climates, forests are composed of a mnch
greater diversity of trees than they are in our less genial
latitudes; and the more you travel northward, or the
greater the elevation of the land, the more homogeneous
the woods become.
26*
.300 oN THE cultivation of TREEs.
CAROLINE.-I have observed this, both in travelling in
Scotland and in ascending the mountains of Switzerland.
The walnut, the oak, and the birch successfully disap-
pear, and, the summits are almost always crowned with
firs.
MRs. B.--It is remarkable, that under the same lati-
tude, America can boast a much greater variety of trees
than Europe: we possess but thirty-four species, while
she has no less than one hundred and twenty. It is to be
hoped, at least, that we shall be able to increase our
stock from so well furnished a market.
Exily.—America being a more recently settled coun-
try, and less populous, can afford to raise wood in a bet-
ter soil, while we, in Europe, are so restricted for space,
that all our good soil is set apart for grain, and we plant
wood only where nothing more valuable will grow.
MRs. B.-That is necessarily the case in all highly
civilised and thickly populated countries; corn being a
more valuable produce than timber, will obtain the prefer-
ence where the soil is adapted to it.
Our natural forests, in such land as we allow them to
occupy, consist of little more than the oak, the ash, the
beech, the birch, and, in elevated situations, the fir.
Forests are divided by botanists into tolerant and into-
lerant: the former admits of trees of another species
growing among them; the latter exclude all but their
OWIle
A forest of oaks is of the former description; under-
wood of various descriptions growing beneath it; while
beeches and firs do not allow this privilege to the inferior
plants, and are hence denominated intolerant.
The thirty-four species of European forest-trees are
divided into four classes.
1st. Class. Trees with hard wood; this class comprises
three species of oak.
Long-stalked oak. Chesnut. Hornbeam.
Stalkless oak. Elm. Pear,
Tauzin oak, Ash. Apple.
Sycamore.
ON THE CULTIVATION OF TREES. 301
2d Class. Trees with soft wood.
Lime. Poplar. Willow.
3d Class. Trees with resinous wood.
Pine. Fir. Larch.
4th Class. Evergreens, not resinous.
The Evergreen Oak, of the south of Europe.
There are two modes of felling forests; which the
French call en Jardinier, or Taille réglé, and for which
we have no equivalent terms in English. In the former,
you successively cut down the large trees as they grow
up to the size of timber; in the latter, the whole of the
forest is felled at once.
Canolise.—The former must surely be the best mode;
for it seems mere waste to cut down the young trees be-
fore they are large enough to be of use.
Mrs. B.-It is difficult to fell the large trees without
injuring the small ones. They are deprived of the shade
and shelter of the large trees, and their roots are often
deranged and their branches broken by the fall of their
protectors. When forests are felled completely, it is
done at regular periods, which are determined either by
the nature of the wood or the purpose for which it is in-
tended. For the ordinary consumption of fuel, it is
usually cut down every twenty years. When the trees
have attained a sufficient size for fire-wood, and in coun-
tries where wood is the only fuel, this is the principal ob-
ject in view. This is generally the case in most parts of
the world. Our island, where coal is so commonly
burnt, forms an exception. We devote much less time
to planting, because we derive our fuel from the bowels,
rather than from the surface, of the earth; and our
woods are raised chiefly to produce timber for building:
but the taille regle is generally adopted on the continent.
It admits, however, of some modification: instead of
cutting down the large trees, and leaving the young
ones to grow up, the young trees are cut down generally
about the age of twenty years; with the exception of
302 ON THE CULTIVATION OF TREES.
the finest plants, which are reserved for the next periodi-
cal felling. These trees are called standards or standers.
The young trees are cut up into faggots for burning, and
into props to support vines: their stumps quickly send
forth new shoots, which at the end of another twenty
years, are fit to be cut down for the same purpose. The
greater number of the standards are then felled, having
acquired dimensions which enable them to be cut into
logs for fire-wood. The standards which escape the
second felling, in France, assume the name of sur taillis :
if reserved a third time, they are called sur écorce; and
should they be so fortunate as to survive the fourth fel.
ling, they become timber.
EMILY.-I really quite tremble for the reserved trees
every time the wood-cutter enters the forest; it is well
they are not endowed with a consciousness of the risk
they run. And at what age are timber trees felled !
MRs. B.-Their length of life will be more likely to
excite your envy than your compassion. Oaks and
beeches are not considered as ripe for timber, until they
have attained the age of 120 or 130 years. After that
period, there is a greater chance of their deteriorating,
than of their improving.
CARollNE.—Wood for burning, then, cut down in the
successive fellings is from twenty to nearly fifty years of
age 7
Mrs. B.-Beech, when not reserved for timber, is not
suffered to live beyond thirty years; because, after that
age, young shoots will no longer sprout from the old
stumps. Resinous trees do not shoot out afresh after
felling; woods of firs must therefore be cut down alto-
gether, and re-sown ; or the forest may be felled in alter-
nate stripes, which is attended with this advantage, that
the stripes left growing shelter the young plants which
shoot in those that have been felled. When the firs are
situated on the declivity of a mountain, as it very fre-
quently happens, the wood-cutters must begin their ope-
rations from below, in order to be able to carry away the
trees with greater facility.
The proper season for felling forests, is from the mid-
ON THE CULTIVATION OF TREES. 303
dle of November to the middle of April; and the instru-
ment best adapted for that purpose is a sharp axe, which
should be used as near the ground as possible; the buds
of the old stumps shooting much more readily when an
axe is used than a saw.
EMILY.—And pray what species of trees do you con-
sider as making the best fuel ?
MRs. B.—That which is heaviest: the weight indi-
cates the quantity of carbon it contains; and you may
recollect that, in the combustion of wood, it is the car-
bon which gives out most heat.
CARo11NE.—Yet I should prefer the wood which pro-
duces most flame. Flanne is so cheerful, that it appears,
perhaps, to give out more heat than it really does.
Mrs. B.-The light which accompanies it, in a great
measure, atones for its deficiency of intensity; but flame
must be considered as a species of luxury, in which
those only can indulge who do not aim at economy in
fuel. The greatest quantity of heat is given out when
the wood burns red, without flame; consequently, the
wood which has the fewest volatile parts producing
flame, and the greatest quantity of carbon, producing red
heat, is the most valuable for fuel. Here is a list of the
varions proportions of carbon contained in equal quanti-
ties of wood of different species:—

the Cubic Foot. the Cubic Foot.
Oz. of Carbon, Oz. of Carbon,
Black fir - * * 86 Beech - tº a • * 64
Red fir tº - 84 Pear º t-e - 54
Evergreen oak - 69 Birch - e e -
Box - tº - 68 Willow - º - 27
Oak - - - 60 Poplar - - - -
I have already mentioned the danger incurred by strip-
ping trees of their bark, in order to harden the wood, by
forcing the cambium to descend through it. This mode
is, however, sometimes attended with success, provided
that it be performed only the spring previous to the trees
being felled; and that the naked tree be charred or slightly
burnt, as a substitute for the covering of which it has been
J04 ON THE CULTIVATION OF TREES.
deprived, and a preservative against the inclemency of the
weather.
CARoline.—That is to say, that the wood is burnt to
save it from suffering from wet ! I should really think
the remedy worse than the disease. In travelling in Italy,
I recollect seeing such miserable flayed and blackened
trees, looking as if they had been put to various species
of torture before the executioner came with his axe to
strike the final blow.
EMILY.—They reminded me rather of poor naked sa-
vages, smeared and tattooed as a substitute for their defi-
ciency of clothing.
Mrs. B.-Why should you not compare them to sheep
shorn of their fleeces in the spring !—the bark of the
tree is no less useful in the arts than the fleece of wool:
you recollect that it contains the astringent principle
called tannin, so essential in the preparation of leather:
it is oak bark which is principally used for this purpose,
as it contains the greatest quantity of tannin.
Let us now consider the cultivation of single trees.
EMILY.—Such as form the ornament of parks and plea.
sure grounds; and those which, dispersed throughout the
country produce such beautiful scenery in England.
MRs. B.—There is certainly no country which can
boast such a natural, and picturesque arrangement of
trees. On the Continent, single trees are generally plant-
ed in rows: in some districts they may be considered as
a supplement to forests. Almost all the trees in Belgium,
for instance, grow in hedge-rows, or in avenues on the
side of high roads. What species of trees should you
think best calculated for the latter purpose?
CARoLINE.-Evergreens would not be suitable; at least
in our northern climates, because the road requires expo-
sure to the sun and wind during winter, and the passenger
requires no shade in that season.
EMILY.—They should be trees which afford sufficient
shade in the summer, but whose foliage is not so thick as
to prevent the road from drying, after heavy showers.
MRs. B.—For this reason the horse-chesnut is not
adapted to such a situation; for, though it would afford
ON THE CULTIVATION OF TREES, 305
excellent shelter to passengers during a shower, it would
render the road damp. Trees with very wide-spreading
roots are also objectionable, as they encroach on the ad-
jacent culture: on this account the acacia is excluded.
EMILY.—But in England the road is almost always se-
parated from the contiguous fields by a ditch, so that the
roots could not well interfere with their produce.
MRs. B.—The roads in England are seldom bordered
with trees, except occasionally in hedge-rows : our cli-
mate being too damp to admit of such an ornament, while
in the southern parts of the Continent trees are almost a
necessary accompaniment to roads, on account of the
shade they afford.
CARoline.—I think fruit-trees, and such as have sweet-
smelling blossoms, should be planted for the gratification
of the passengers.
Mrs. B.-I am afraid that the kindness of your inten-
tion would be frustrated; for as these trees are not the
property of the public, it would be only leading the pas-
senger into temptation, and exposing the tree to danger;
the fruit would be unlawfully gathered, and eaten, in all
probability, before it was ripe; and the tree would suffer
from the pulling and breaking of its branches. When
fruit-trees grow on the high road, the proprietors are often
obliged to fence the stems with briars and brambles, to
prevent their being climbed, and to lop the lower branches,
in order that they may be above the reach of the passen-
QCTS,
* The elm is one of the trees best adapted for the high
road: it may be transplanted without injury, after it has
attained such a growth as to enable it to resist the attacks
of cattle, an essential point for trees so much exposed:
it is robust in its nature, of long duration, and affords a
light and pleasant shade : its roots are superficial, and
yet not spreading, and it bears neither flowers nor fruit
which can tempt the passenger.
The plane, a tree very common on the Continent, is
also well adapted to roads. It comes into leaf very late,
so that the roads have full time to dry in spring. The
oak is so robust and durable a tree, that it would be ex-
306 ON THE CULTIVATION OF TREES,
cellent for this purpose, could it be transplanted sufficiently
large to preserve it from accidental injury; but it suffers
from transplanting unless very young. The best mode
of rearing oaks for avenues is to plant them in hedges:
the bramble, or other shrubs of which the hedge is com-
posed, afford them shelter and defence, until they are of
an age to resist accidental injury; the hedge may then
be cut down at pleasure. This has also the advantage of
forcing the roots of the oak to descend; for the roots of
the hedge, being more superficial, consume the nourish-
ment near the surface of the soil, and compel those of
the oak to seek it in a lower region.
The birch is well calculated for roads, if the soil be
sandy; it thrives in a cold climate and in elevated situa-
tions, and the lightness of its foliage is an additional ad-
vantage in such temperatures.
The sycamore is a beautiful tree for avenues. The
hornbeam is objectionable only on account of the slowness
of its growth. The aspen, the ash, and the poplar, are
well adapted to a moist soil, as they help to drain it. An
avenue of poplars is not picturesque, it is true, but it aſ.
fords almost as much shelter from the wind as a wall, and
in some situations this is very desirable.
EMILY.—A few poplars, interspersed with other trees,
ſorm, I think, beautiful groups; but an avenue of poplars
is associated with the idea of marshy ground, and from
its formality is extremely ugly.
MRs. B.-In planting trees by the road-side, the holes
should be made both deep and wide; for the ground not
being cultivated is hard and compact, and the young
roots would be unable to penetrate it, were it not prepared
and lightened by the pick-axe or the spade.
The young trees should never be headed or lopped;
it thickens their foliage, but destroys the natural charac,
ter of the tree. Some of their lateral branches may be
slightly pruned; for as the branches in general corre-
spond with the roots, the more erect the former grow, the
more the roots will descend into the soil.
CARoline.—The beauty of the greater part of the
frees on the Continent, is spoiled by the merciless mode
ON THE CULTIVATION OF TREES. 307
they have of heading them when young, in order to make
them grow thick and bushy.
MRs. B.—In transplanting young trees, the more they
are lopped, the more certainty there is of their living;
and nurserymen who usually supply them, and warrant
their taking root, make no scruple to amputate both head
and branches.
CARolix E.-The life of the plant may be thus secured,
but it no longer deserves the name of a tree; it is a stake,
or a pole ; which, though it may throw out branches, will
never have the free, natural character of its species. Is
it not, therefore, far preferable to run some trifling risk
of losing them, rather than mutilate them in so barbarous
a manner?
MRs. B.-I perfectly agree with you : besides, the
risk is so trifling. In transplanting trees into the bota-
nical garden at Geneva, the branches are never lopped,
and only about five per cent die : yet the chance of their
perishing must greatly exceed that of common trans.
plantations, as the trees come from foreign climates, and
are placed in a soil and temperature more or less unsuited
to them ; besides which, they have undergone the con-
finement of packing, and the fatigues of a long journey.
It must, however, be acknowledged, that the art of pack-
ing and conveying plants is highly improved; for M. De
Candolle frequently receives plants, not only in leaf, but
in full blossom.
If, however, gardeners will persevere in this system of
łopping, they should at least do it with moderation and
judgment.
EMILY-There is, however, some apology for nursery
gardeners: the trees, in their grounds, are so thickly
planted, that they cannot be taken up without injury to
their own roots, or to those of their neighbours; and if
the roots be cut, is it not necessary also to lop the branches,
for mutilated roots can ill supply the whole of the branches
with nourishment?
Mrs. B.-Your observation is very just : but young
frees, raised with a view to transplantation, should never
27
J08 ON THE CULTIVATION OF TREES.
be allowed to grow so thickly, as to interfere with each
other; it is the duty of a nurseryman to transplant them
in his own grounds, in order to give them space, if he has
not a market for them elsewhere.
When a very large tree is to be transplanted, it is ad-
visable to do it in the heart of winter, during a frost; a
trench should be dug round, and, as far as attainable,
below the stem of the tree, and be filled with water, if the
rain does not sufficiently perform that office. When the
water is frozen, the tree will he inclosed, as it were, in a
vase of ice, and may be taken up with the clod of earth
attached to it; and, contained in the icy vase, it may then
be conveyed to the place of its destination, almost without
being sensible of its change of situation. This is, how-
ever, a very expensive operation, as it requires a conside-
rable mechanical force to accomplish it; it can be done,
also, only where the frost is severe and of long duration ;
for if the vase be melted or broken before the tree is
placed in its new situation, the whole fails.
Sir Henry Stewart of Allanton has, within a few years,
introduced a mode of transplanting large trees, which ap.
pears to have been attended with great success. It is
precisely the reverse of that I have mentioned, yet found-
ed on the same principle of guarding the roots from in-
jury: with this view, instead of carefully covering up the
roots, he lays them bare, but he separates the earth from
them with such extreme precaution, that not even the
smallest fibres are injured : this is done by labourers,
whom he calls pickmen; because their business is to clear
the roots from the earth by means of a small instrument
adapted to the purpose, or with their fingers: a ball of
earth is left close to the stem with the sward upon it. An
engine is then brought up to the tree, consisting of a
strong pole mounted upon two high wheels; the pole is
strongly secured to the tree, while both are in a vertical
position, they are then brought down to a horizontal one,
by the pole acting as a lever; and by its descent, the few
central roots, which the pickmen could not reach, are
rent from the ground. The trce is so laid on the machine
as to balance the roots against the branches, and one or
two men are placed aloft among the branches of the tree,
ON THE CULTIVATION OF TREES. 309
where they shift their places like moveable ballast, as oc-
casion may require. Both roots and branches are care.
fully tied up. The pit for receiving the tree, which
should be prepared a twelvemonth before, is now opened,
and the tree set in the earth as shallow as possible. The
roots are then loosened from their bandages, and divided
into the tiers, or ranks, in which they grow from the stem;
the lowest of these tiers is then arranged, as nearly as
possible, in the manner in which it lay originally, each
root with its rootlets and fibres being imbedded in the soil
with the utmost precaution, the earth being carefully work-
ed in by the hand and the aid of a small rammer: addi-
tional earth is then gradually siſted in, and gently knead-
ed down, till it forms a layer, in which the second tier of
roots is extended in the same manner as the lower tier,
and so on till the whole are covered with earth. This at-
tention to incorporate each fibre of the roots with the soil
not only answers the purpose of inducing the roots to re-
commence their function of absorbing sap, but also serves
to fix and secure them firmly in the soil, and renders
stakes, ropes, and other means of adventitious support un-
necessary.
CARoll NE.-And by your account this does not appear
to be a very expensive process.
Mrs. B.-No; independently of the engine, which is
very simple, it is estimated that trees from twenty-six to
thirty-five feet high, may be moved half a mile, at the ex-
pense of from ten to thirteen shillings. But the experi-
ments have always been made with healthy trees, whose
roots and branches have had ample space for growth; not
tall emaciated plants torn from the interior of forests, with
stinted roots and branches, and so little vigour of vegeta-
tion, that their bark would not be either of sufficient thick-
ness or hardness, to shelter the stem from the rude blast,
nor the roots of sufficient strength or extent, to fix it firmly
in the soil. Sir Henry Stewart, therefore, particularly
recommends transplanting trees which have been freely
exposed to the advantages of light and air; and should
they, by such exposures, have suffered in their growth on
the weather side, he advises, in transplanting them, to re-
J10 ON THE CULTIVATION OF TREES,
verse the aspect, in order to shelter the weak side of the
tree, and expose the luxuriant one to the severity of the
wind.
ExIILY.—By this means, then, large trees may be
transplanted without either cutting the roots or lopping the
branches 7
MRs. B.—By adopting all the precautions I have men-
tioned, it appears that scarcely a tree failed. Sir Henry
is, no doubt, perfectly correct in not cutting, even the little
tassels of rootlets which grow at the extremities of the
roots, provided the operation of transplanting be perform-
ed with so much caution that these suffer no injury; but
if the spongioles be crushed, or the fibres any way muti-
lated, it is better to amputate the extremilies, which will
shoot afresh, more quickly than the rootlets would recover
of their wounds.
It is wrong to plant in wet weather; for, though water-
ing is required after planting, the hole in which the tree
is placed must not be filled with mud : it would greatly en-
danger the roots.
In such wet countries as Holland, they are often obliged
to bury faggots beneath the soil intended for planting, in
order to increase the filtration of the water.
From the cultivation of trees we shall proceed to that
of hedges: these are destined either for shelter or defence.
In former times there was a third description of hedges de-
signed for ornament; but our landscape-gardeners have
entirely exploded the grotesque figures, cut out in box and
yew, which excited the admiration of our forefathers.
That district in the west of France, called the Boccage,
derives its name from the high and bushy hedges with
which it abounds, and which are designed to afford shelter
from the stormy winds of the Atlantic. There are but
few trees in those parts; but the hedges, being from eight
to ten feet in height, are sufficient to protect the crops
from the boisterous sea-breezes, and they thence bear the
name of brise vent.
CARollins.—In England, our hedges are calculated
more for defence; but the trees, with which they are
interspersed, serve also the purpose of shelter.
MRs. B.-Our climate is unfortunately so damp, that
ON TIIE CULTIVATION OF TREES. 311
exposure to the sun and air is rather an advantage than
otherwise.
Hedges for defence answer the double purpose, of en-
closing cattle in their pastures, and excluding those which
might trespass on it.
EMILY.—Does it not also afford a security against
thieves 7
MRs. B.-It has been so considered, but I am inclined
to think, erroneously. A thief may lie concealed, and
lead away a sheep or cow at night, under cover of a
hedge, without being discovered; while there is scarcely
any night so dark, that he might not be perceived on an
open plain.
It is objected to hedges, that they occasion a waste of
ground : when necessary, therefore, they should be
made to occupy as little space as possible, and be thick-
ened, by crossing and engrafting the branches on each
other, rather than by planting a double row. An exter-
mal ditch is liable to the same objection ; but it has the
double advantage of serving as a defence to the hedge,
and of raising a bank, which gives additional elevation to
the hedge when planted on it. When the shoots are two
years old, they may be crossed and fastened by a worst-
ed thread, and they will engraft themselves; for the fric-
tion of the ligature will wound the young bark sufficiently
to expose the cortical vessels, and enable them to unite
with each other.
EMILY.—The plants have, then, a double source of
life ; and, if one of the stems should perish, its branches
would be fed by those on which it is grafted.
MRs. B.-Yes; and the dead stem may be cut away
without injuring the hedge. By this system of crossing
and graſting the branches, the hedge becomes so thick as
to be absolutely impassable. Great attention should be
paid, not to plant hedges of shrubs which grow thin at
the base, or have spreading roots. The hawthorn or
quickset is decidedly the plant best adapted for hedges;
its shoots branch out in such a variety of directions, and
cross and intersect each other so frequently, as to render
all ligatures for that ºpºnnectiºn.
tºº
312 ON THE CULTIVATION OF TREES.
The Paliurus aculeatus succeeds well in dry soils. It
is armed with two species of thorn, one of which is
straight, the other curved : so that the animal that would
trespass, if it can avoid the straight thorns, on entering
the hedge, has very little chance of escaping the crooked
ones in passing through it. º
The barberry is well adapted for hedges, having three
thorns issuing from the same point. The Ilex is furnish-
ed with thorns at the extremity of its leaves. The Lentis-
cus (Pistachia Lentiscus,) and the Cockspur Hawthorn
(Crataegus crusgali,) are shrubs which admit of planting
in hedge-rows; but their cultivation does not extend
further northward than the southern parts of Europe. .
CAROLINE.-I begin to think we have been confined
long enough by these hedges; and I am impatient to
break through them, to get into the orchard, and exam-
ine the fruit-trees, which are of a much more interest-
ing nature.
MRs. B.-I was just going to direct your attention to
them. You will be surprised to hear that, of one hundred
and twenty families of fruit-trees, known in Europe, we
cultivate only seventeen; and by far the greater part
of these have been brought from the other quarters of
the world. The apple and the pear, some few cherries,
and the raspberry and strawberry, are alone indigenous
in Europe.
CARoline.—Alas! what a poor figure our quarter of
the globe makes in the vegetable kingdom
EMILY.—We have the greater merit in having cnrich-
ed it with such a number of foreign plants.
Mus: B-True. These seventeen families give us
thirty-four genera, sixty-eight species, and, finally, about
two thousand varieties of fruit-trees: a number which is
multiplying every day, from the increased facility of inter-
course with foreign countries, and the improved mode of
cenveying plants, united to the general progress of
SC16. In Ce.
CARollNE.—From what countries do we derive our
choicest fruit-trees.
MRS. B.-Chiefly from the East. Africa is but very
ON THE CULTIVATION OF TREES. 313
imperfectly cultivated ; and America, though so distin-
guished for its forest-trees, appears to be very scantily
supplied with fruit-trees. The Opuntia, the loiospyros,
and a few others, are the only fruit-trees that have been
brought to Europe from the northern parts of the New
World.
The orange and citron we derive from Japan; the po-
megranate from Africa.
New Holland, which contains not less than three or
four thousand different plants, has but three or four
species of fleshy fruit-trees, and the fruit of these is small
and insipid.
In some fruits, we distinguish those in which the fleshy
part is attached to the nut or kernel, as the plum and the
peach, and those which are separated from it, as the apri-
cot. Peaches, plums, apples, and pears, are of the fami-
ly of Rosaceae.
CARoline.—This family is, then, equally celebrated
for the beauty of its flowers and the excellence of its
fruits. ©
MRs. B.-There are two species of peach, both of
which we derive from Persia : one of them, having a
smooth skin, we distinguish by the name of Nectarine.
Each of these species has two varieties, in one of which
the pulp adheres to the stone, in the other it is separate
from it.
The other members of this family are the almond, the
apricot which comes from Armenia, and the cherry, of
which there are five species. There are besides, of
this family, the plum, the strawberry, the rose, the ser-
vice-tree, and the medlar.
The orange forms a family of its own, bearing its
name Aurantiaceae, and includes the lemon, the citron,
and the pample, or mousse.
The sweet orange and the bitter were formerly sup-
posed to be of the same species, and the sweet was often
grafted on the bitter orange; but this is an error: they
are of different species, and the sweet orange does not
require grafting.
There are no less than twelve known species of wał.
314 ON PLANTS WHICH PRODUCE
nut-trees; one of which we derive from Syria, and the
eleven others from America. We cultivate the first for
its fruit, but the latter produce the finest timber.
CONVERSATION XXIX.
ON THE CULTIVATION OF PLANTS WHICH PRODUCE
FERMENTED LIQUORS.
MRs. B.-There exists in all vegetables, though in
very different proportions, a saccharine substance from
which sugar is obtained; and this substance is suscepti-
ble of being converted into alcohol, or spirit of wine.
For this purpose it is not necessary to resort to the labo-
ratory of the chemist: when placed under favourable
circumstances, the transformation takes place spontane-
ously by a process called fermentation.
EMILY.—It is a process with which we are already
tolerably well acquainted, as you explained the different
fermentations to us in our Conversations on Chemistry.
MRs. B.-You will then recollect that the juice of all
fruits when expressed, will (like that of the grape) fer-
ment; and that during this process a general disorgani-
sation of the parts take place, and a new arrangement is
established, in consequence of which the sugar or sac-
charine matter contained in the liquor will be converted
into spirit. But fermentation is not confined to the juice
of fruits: spirit may be obtained from any part of a plant
containing the saccharine principle ; thus the sap of the
palm-tree, when fermented produces palm wine.
CAROLINE.-It is to be regretted that we have no trees
whose sap can be fermented; it would be so much more
easily obtained than fruit.
MRs. B.—The sap of the birch is sometimes fermented.
But you may recollect that the vinous ſermentation is
freqently followed by another of a very different nature,
called the acetous fermentation, which reduces the wine
or spirit to vinegar: this occurs in some measure with
the fermented sap of the birch; it becomes slightly acid,
FERMENTED LIQUORS. 315
and may therefore be considered rather as a refreshing
than a spirituous beverage. All sap would yield spirit;
but, independently of its susceptibility of turning acid,
the liquor would, in general, be insipid. The excellence
of wine is not confined to the spirit it contains, but to its
aromatic flavour; and this is produced by the fermenta-
tion of fruit. If spirit of wine alone be required, it may
be obtained from potatoes or any other vegetable, how-
ever insipid. Brandy and common spirits are, in Eng-
land, usually distilled from fermented grain : gin has
more flavour, as the juniper berries are distilled with the
spirit.
EMILY.—Yet grain does not appear to contain any
sugar !
MRs. B.—Though grain is not sweet to the taste, it
contains the elements which produce sugar, and the mode
of developing this substance, is to make the grain begin
to germinate. For this purpose, barley is moistened and
exposed to a certain elevation of temperature which
stimulates germination; the saccharine principle is thus
produced, and the grain becomes sweet: the germina-
tion is then suddenly stopped by drying the barley in a
kiln or heated oven; in this state it is called malt.
When mixed with water, the liquor is so sweet as to have
obtained the name of sweet-wort, and its fermentation
produces beer; but this would be a very insipid beve-
rage, were not hops added previous to the fermentation,
to give it the flavour and astringent quality found in fruits.
The fermentation of apples produces cider. There
are three species of apples, the sweet, the sharp, and the
acid. The two former, fermented together, produce ex-
cellent cider: the sweet apple supplies the spirit; the
sharp, the astringent principle ; but the sour apple is not
fit for fermentation. In order to make good cider, it is
not only essential to choose the races of apples, but they
must be gathered with care to avoid being bruised; they
should then be collected into heaps, in which state they
ripen and exude moisture : they must next be crushed
and reduced to a pulp, and ºr of water added; the mass
is then pressed to obtain the juice, which ferments spon-
tancously, and produces cider,
316 ON PLANTS WHICH PRODUCE
Extrix-Perry is, I believe, obtained from pears in a
similar manner'ſ
MRs. B.-Precisely. But it is to the vine that we are in-
debted for the most precious of our fermented liquors. This
plant is of the family called Sarmentaceae. It bears al-
ternately clusters of grapes, and of leaves, opposed to
each other on the stem. The vine derives its origin
from the countries situated between Persia and India: it
was brought by the Phoenicians to Greece, and thence
conveyed by the Phocians to a colony they had formed
in that part of Gaul, where Marseilles is now situated.
EMILY.—The vine is a plant of such interest to so-
ciety, that its history can be traced with more accuracy
than that of most other plants.
MRs. B.-Hence governments have interfered more
with the culture of the vine, than with that of any other
plant. Numa Pompilius first introduced it at Rome.
The Emperor Domitian ordered all the vineyards to be
rooted up. Charlemagne protected the culture of the
vine; while Charles "X. discouraged it. His successor,
Henry IV., re-established it, and ever since it has
flourished in France.
CARolin E.-It appears, then, that cruel and tyrannical
sovereigns forbade the culture of the vine, while the
humane and enlightened ones encouraged it; and yet
the former could have been influenced only by its moral
effects on their subjects; for it was evidently prejudicial
to the interests of the country, to destroy so valuable a
branch of commerce.
Mrs. B.—Commercial interest was very imperfectly
understood in ancient times, especially by unenlightened
sovereigns; these, therefore, considered only the prejudi-
cial effects of the vine in producing intoxication, while
the better informed esteemed it not only as a source of
wealth, but of health and comfort to those who enjoyed it
without excess, and this latter class is certainly by far
the most numerous.
EMILY.—I have heard it observed, that there is less
intoxication in wine countries than in the more northern
districts, which do not admit of the growth of the vine.
FERMENTED LIQUORS. 317
MRS. B.-In England, for instance, it is cheaper to
drink spirits than wine, or even than strong beer; and as
alcohol is the intoxicating principle, these distilled liquors
have a more intemperate tendency. The culture of the
vine, since its introduction into Europe, in extending
northwards, has spread itself more to the east than to the
west, because the eastern part of this continent is hotter
in summer than the western, under the same latitude.
Now, the vine derives more advantage from the heat of
summer than it suffers from the cold of winter: in the
latter season it does not vegetate, so that it requires only
the degree of temperature necessary to escape freezing,
while heat in summer is absolutely necessary to ripen the
grapes; and you have seen that the vine succeeds much
better in Switzerland than in England, because, though
the winters in the former are generally colder, the sum-
mers are hotter.
CAROLINE.-We read in history, of vineyards growing,
and wine being formerly made, in England. Do you
suppose that the climate was then warmer than it is now !
MRs. B.-No ; but the palate of our ancestors was
probably not so delicate as that of their descendants.
The same has been affirmed of Brittany and Normandy,
provinces in which vineyards are now unknown, and
where the vine is cultivated, as in England, trained
against walls in a favourable aspect; and even then the
grapes ripen but imperfectly. If wine was really ever
made in those countries, it must have been a beverage
very analogous to vinegar; but it is very possible that
such wine was once produced: for the fact is ascertained,
that in proportion as the means of transport have increased,
the extent of country in which the vine is cultivated, has
diminished.
Exily.—I should have imagined that the increase of
high roads, canals, and shipping, would, by diminishing
the expense of conveyance, lower the price of wine, and
thus render it more attainable to thc northern countries,
where it is not grown.
MRs. B.-Your argument is perfectly just : the in-
creased facility of conveyance, augments the demand for,
tº
3.18 ON PLANTS WHICH PRODUCE
and consequently the production of wine ; but that does
not prevent its restricting the extent of latitude in which
the vine is cultivated. When wine could be conveyed
from the south of France to Brittany and Normandy, of
a much higher flavour and better quality than that which
was produced in those provinces, and with but little addi-
tional expense, the Bretons and Normans gradually
converted .their vineyards into corn and pasture, and
exchanged their grain and cattle for the juice of the grape.
CARoline.—While the increased demand for wine,
must have induced the southern districts to convert their
pasture and, corn fields into vineyards. The same
reasoning will hold good with regard to England; and
wine must have been conveyed across the Channel, to
the utter destruction of the English vineyards. You see,
Mrs. B., that I have net forgotten your lessons of political
economy.
MRs. B.-I am glad to hear you remember them so
well : the cultivation of vineyards at present extends
from 29° to 50° of latitude, as far south as Shiraz, in
Persia; as far north as Cologne, on the Rhine.
EMILY.—Pray, does not the vine grow naturally in
America? &
MRs. B.-It does; but it is of a different species; and
grows only wild. The vine which is cultivated, is
brought from Europe; but its introduction has not hi-
therto been attended with complete success.
EMILY.—I am surprised at that; as the islands of the
Atlantic, Madeira and the Canaries, are so celebrated for
their wine.
Mns. B.-On the continent of America, all the grapes
in the same cluster frequently do not ripen at the same
time; so that when gathered, some are decaying, while
others are not yet come to maturity: and this circum-
stance, which is not yet accounted for, prevents the wine
from being of a good quality.
It is at the Cape of Good IIope that the vine has made
the most remarkable progress, and particularly since
England has been in possession of that colony. While
it belonged to the Dutch, it produced only a small quan-
FERMENTED LIQUORS. 319
tity of rich Cape wine; but now a variety of different
vines are cultivated there with great success, and the
Cape Madeira will, perhaps, ultimately rival that of the
Atlantic island.
The height at which the vine can be cultivated from
the level of the sea, is four hundred fathoms.
EMILY.—But that must vary according to the latitude.
Mrs. B.-No doubt; this is the elevation of the most
northern limits of the cultivation of the vine in France.
There are many circumstances to be attended to, in the
culture of a plant of so much importance as the vine.
In the first place, the nature of the plant: the varieties
are innumerable ; there are no less than six hundred in
the botanical garden of Geneva; the fruit differing either
in colour, form, flavour, consistence, &c. : the degree of
flavour, of firmness and compactness of the fruit, is, in
general, proportioned to the heat of the climate. The
flavour of the muscat grape is, however, richer than that
of the common grape in any climate.
Every flower of the vine contains five seeds, two or
three of which often fail.
CARoll NE.-The soil must labour hard to ripen so
many seeds.
MRs. B.-No cultivation requires greater care to
repair the exhaustion which it undergoes, and attention
to prevent weeds from engrossing any portion of that
food which is so much in request. Yet a great deal of
manure should not be used, for it injures the quality of
the fruit, though it increases the quantity.
The grapes should be neither very close, nor very
distant from each other in the cluster, but so far apart as
to leave sufficient space for each grape to attain its full
growth. For this purpose, the grapes of Fontainebleau,
when young, are thinned by the scissors. But these
grapes are cultivated exclusively for eating, and sold at a
price which repays such an expensive mode of culture.
There is also great diversity in the degree of precocity
or tardiness of this plant. When it shoots early, there is
danger of its suffering from the frost in spring; if late,
it may not have time to ripen its fruit in autumn. Care,
28
320 ON PLANTS WHICH PRODUCE
thereſore, should be taken to choose the medium, espr.
cially in cold climates.
Old plants produce the finest fruit, but in the smallest
quantity. It does not, therefore, answer, to continue to
cultivate the same plants, above a certain number of years.
CARoLINE.—So that they are not allowed time to meet
in the course of nature with their accidental death 7
Mrs. B.—Not often. The influence of climate on the
vine is very considerable. The greater the degree of
heat, the more sweetness is developed in the fruit, the
greater is the quantity of alcohol produced by fermenta-
tion, and the astringent principle is proportionally dimi-
nished : but this may be carried too far; a certain admix-
ture of the astringent principle is both wholesome and
palatable. The grapes of Fontainebleau will not produce
good wine, from not possessing a sufficiency of this prin-
ciple; and, accordingly, we find that the wines in highest
estimation are not those produced in the hottest climates,
but in countries situated between 30° and 45° of latitude.
The aspeet most favourable must be determined by the
locality of the situation and the latitude. The vines of
Epernay, which produce the finest champagne, have a
northern aspect; those situated on the two opposite banks
of the Rhone, in the neighbourhood of Avignon, yield
equally good wine; but, in colder climates, the more vine-
yards are exposed to the south the better they thrive.
It is rather singular, that fine grapes may be produced
in almost every kind of soil, provided the vine be of a
nature to suit it. The vineyards of Bourdeaux are plant-
ed in a gravelly soil, and hence bear the name of Win de
Grave; those of Burgundy in calcareous clay; hermit-
age grows in granite; and Lacryma Christi is raised in
the volcanic soil of Mount Vesuvius. The vineyards of
8witzerland grow in stiff, compact, calcareous earth.
In order to determine upon the mode of culture, the
question must first be ascertained whether it be grapes of
the finest quality or in greatest quantity that are required.
In hot countries, the former are most in demand; in cold
countries, the latter is principally aimed at: for in dis-
tricts which form the limits of the cultivation of the vine,
it is desirable to produce a large quantity of wine, though
FERMENTED LIQUORS. 321
it be of inferior quality, for the beverage of the common
people, who cannot afford to pay the conveyance of wines
from more favourable climates.
An argillaceous soil produces but indifferent grapes,
even in a favourable climate. Under such circumstances,
therefore, quantity rather than quality is aimed at, in order
to obtain spirit for brandy; for in wine countries brandy
is distilled from wine rather than from grain. For this
purpose, the plants, instead of being kept low, as you have
seen in France and Switzerland, are allowed to grow to
a great length, and are suspended in garlands from one
tree to another.
CARolin E.-This mode of cultivation is adopted in
Italy for the production of grapes for wine, and is most
beautiful in appearance.
MRs. B.-But the fruit is not of so fine a quality; and,
consequently, the wine is not so good. In the south of
France, as well as in Italy, vines are often cultivated
without being propped, and the branches are suffered to
grow six or eight feet in length.
During the wars of the Revolution, the French having
destroyed all the props of the vineyards in the valley of
the Rake, on the banks of the Rhine, the peasantry were
obliged to let the vines grow without support; when, in-
stead of being deteriorated, they found the fruit so much
improved, that they have ever since continued the same
system.
EMILY.—Then I conclude that they did not allow their
vines to shoot out to a great extent.
Mas. B.-No doubt; or the fruit would have been
impoverished, instead of being improved. The use of
props in vineyards is, perhaps, carried to the extreme.
M. De Candolle suggests the experiment of fastening four
plants to one prop, placed in the centre. In doing this,
the branches would be curved towards the prop, and the
descent of the cambium retarded.
CARolin E.-We have seen vineyards in some parts of
Italy trained on a horizontal trellis-work, the grapes being
Auspended beneath the verdant roof. In other places,
the vines are trained over trees, which are planted merely
322 CULTIVATION OF GRASSEs,
to afford them support, and they derive a little shelter
from the leaves, which grow on the few branches which
are not lopped.
Mrs. B.-These various modes of training vines,
though they may be used in hot climates with less injury
to the fruit, never fail, more or less, to be prejudicial to
it; and though the climate of Italy is generally hotter
than that of France, the latter is celebrated in all parts of
the world, for the excellence of its wines, while those of
the former are scarcely ever exported.
In hot climates, the grapes are sweet, contain less acid
and astringent principle, and the fermentation is less com-
plete, the proportions not being so well adjusted as in
France, and other countries of a more moderate tempe-
rature.
It will be unnecessary for me to enter into any further
detail on the nature of the vinous fermentation, as it is a
chemical process, an account of which, you may recollect,
I have formerly given you.
CONVERSATION XXX.
ON THE CULTIVATION OF GRAsses, TUBEROUS
ROOTS, AND GRAIN.
MRs. B.-The objects of culture which we shall next
investigate are the grasses.
The principal use of the grasses is to feed cattle,
which, both during their life and after their death, are
useful to us in so many different ways. The advantage
we derive from them in agriculture is not confined to the
labour they perform in the field; they also supply manure;
and the more forage we produce for cattle, the greater is
the quantity of manure we shall be able to spread upon
our fields.
EMILY.—Poor soils, then, must require more cattle, and,
consequently, more grass-land, than rich ones, But may
not cattle be fed on other vegetables besides grass?
TUBEROUS ROOTS, AND GRAIN. 32.3
Mrs. B.-Unquestionably; cattle will eat the same
vegetables that serve for our snbsistence; but we reserve
these for our own use, and feed them on those which
would afford us little or no nourishment, such as grasses.
These ure of two kinds, natural and artificial. The na-
tural grasses are of the gramineous family, which belongs
to the class of monocotyledons, or endogenous plants.
EMILY.—Yet how very little resemblance they bear to
the palm-tree, or other tropical endogenous plants.
MRs. B.-They are not so dissimilar as you imagine,
since they grow like them internally.
CARoLINE.-They may then be considered as the
miniature palm-trees of our ungenial climates, being con-
tracted both in space and time; for the mower comes
with his destructive scythe, before they have passed
through a single season.
Mrs. B.-The natural grasses are either annuals or
perennials. The first are very rarely used for meadows.
In some countries, however, rye, Indian corn, and millet
(all of which are annuals), are sown as grasses; that is
to say, for the sake of their leaves, which are mown as
soon as they appear above ground, and thus, several suc-
cessive crops are obtained in one season.
But our meadows are all formed of perennial grasses :
they are sown with hay-seed, which consists of a mix-
ture of various sorts of grasses, more or less adulterated
with the seed of weeds. These different grasses, ripe-
ning at different periods, a medium must be taken to mow
the crop.
Ewily.—Would it not be better to sow only one spe-
cies of grass 7
MRs. B.-Yes; provided it were first ascertained,
what species would best suit the soil and climate. There
are some agriculturists, however, who dispute this opi-
hion, and think that a variety of grasses makes the best
fodder for cattle. Several naturalists are now engaged
in endeavouring to raise very pure unmixed grasses, with
a view to produce seed for sale : a measure which will
greatly tend to the improvement of meadows.
28*
J24 CULTIVATION OF GRASSES.
CARoll NE.--Do not meadows occasionally require to
be sown afresh 7 for as the crops are either pastured or
mown before the seeds are ripe, it cannot re-sow itself;
and the grasses, though perennials, do not, I suppose,
last a great number of years.
MRs. B.-Grasses are renovated, not so much by seed
as by means of their roots and subterraneous branches,
which spread out in various directions, interweaving and
forming a sort of network of roots and branches; and
from this reticulated mass spring abundance of new
shoots, which thicken and renovate the meadow. If
grass be kept short, it consumes less nourishment, and a
greater quantity remains to push out fresh shoots.
EMILY.—This accounts for the fine thick turf of which
our lawns are composed, and which, being so continually
mown or fed off by sheep, precludes the possibility of
their ever re-sowing themselves.
Mrs. B.—This, however true in England, where the
climate is temperate and moist, will not hold good in
countries where the grass is burnt up in summer, when
mowing cannot take place ; and it is for this reason that
it is impossible on the Continent to produce those beau-
tiful lawns, so ornamental to our country seats.
These lawns, when first prepared, are not usually
sown, but the grass is laid down in sods. By this means
the roots are obtained ready matted, together with a thick
fine turf, which it would require many years' growth,
and constant mowing, to produce from seed.
Meadows are mown in England but once, or, at most,
twice in the season; while, in many parts of the Conti-
nent, three or four crops are obtained, according as the
soil is dry or moist, elevated or low.
The Phleum, the Dactylis, the Anthoxanthum, and
Rye-grass, are the plants best adapted for meadows;
but Rye-grass, degenerates in the dry warm climates of
the Continent, as it requires a great deal of moisture to
keep it fine and tender.
EMILY.—The great defect of grass, which I have ob-
served both in France and Switzerland, is the quantity
TUBEROUS ROOTS AND GRAIN. 3.25
of weeds which are mixed with it, and which renders the
hay strong and coarse.
Mrs. B.—That is owing to the impurity of the seed,
and is attended with every possible disadvantage. The
coarse leaves of the weeds are not only unpalatable and
unwholesome for cattle, but in growing they fill the
spaces which the grasses would occupy, and, by separa-
ting them, prevent their roots from combining and giving
rise to new shoots.
There are some meadows which, from peculiar cir-
cumstances, are not susceptible of being mown. The
grass of mountains, for instance, does not grow sufficiently
high to require it. Being frequently covered with mists,
it remains green throughout the summer; much resem-
bling our English lawns, and affording delicious pasture
for cattle when the meadows in the valleys and plains are
burnt up. The fine turf on the mountains of Switzer-
land and the Alps, consists principally of phleum, inter-
mixed with other herbs of an inferior quality. The mat-
ted roots of these grasses are extremely useful in pre-
venting the surface of the soil from being washed down
by rains: the meshes of the net-work which they form
confine the earth and retain it, as it were, in a basket on
the surface of the declivity. It is on this account very
imprudent to attempt tillage on the sides of mountains.
Small flat patches of land, which are occasionally met
with in such districts, may be cultivated with advantage,
but it is dangerous to displace the fence which Nature
has provided; and however inadequate the means may
appear to the end, it is certain that the massive moun-
tains are upheld, by the feeble roots of some of the
smallest of the vegetable species.
EMILY.—That is, indeed, wonderful! but it is merely
the surface of the soil which the roots of the grass sup-
port.
MRs. B.-True ; but if one surface were washed
down, another would be exposed to the same danger ;
and thus, in the lapse of time, successive surfaces would
be destroyed, and the mountain finally be brought low !
Another species of meadows incapable of being mowii
326 CULTIVATION OF GRASSEs,
are common fields, every parishioner having a right of
pasturage; a circumstance which renders this species of
tenure extremely disadvantageous: it is, in fact, con-
demning the land to yield as little produce as possible.
Let us now proceed to the artificial grasses, the most
benevolent of all the vegetable tribe. It is to them that
we are indebted for repairing the injury which the land
sustains from the culture of grain. They were first in-
troduced into France by the celebrated agriculturist, Oli-
vier de Serres, in the sixteenth century.
EMILY.—These grasses do not, I suppose, form per-
manent meadows, but are sown alternately with crops
of corn, in order to recruit the soil after the exhaus-
tion it has undergone from the latter.
MRs. B.-Certainly : thus alternated, they form an
excellect course of cropping. Most of the artificial
grasses are of the leguminous family; among these the
vetches and the scarlet clover are annuals. The com-
mon purple clover lasts two or three years. It is
difficult to obtain the seed unadulterated by that of
other plants. Clover has long been cultivated on the
left bank of the Rhine, for the sole purpose of produ.
cing seed for sale : this commerce was chiefly carried
on with England ; for though we cultivate a considera-
ble quantity of clover, we use it, almost wholly, as food
for cattle ; our summers seldom being hot enough to
ripen the seed, so that we are obliged to have recourse
to that of foreign growth. A very profitable trade was
carried on with us in this article, when Buonaparte issued
his decree against exportation, and the poor agriculturists
on the left bank of the Rhine, then under the dominion
of France, were nearly ruined. The Germans on the
opposite bunk, supplanted them in a branch of commerce
they were compelled to abandon: England continued to
be equally well provided with clover seed; and it was
Buonaparte's own subjects who alone suffered by his ab-
surd prohibition.
Saintfoin, or Esparcette, is another artificial grass of
the leguminous family, of longer duration than clover.
The seed appears larger than it really is, because it is
TUBEROUS ROOTS, AND GRAIN. 327
sown with the husk or pericarp, and no less than twenty
pounds of seed is required per acre ; whilst ten or twelve
pounds of clover seed, which is sown without the husk, is
sufficient.
Lucerne, also of the leguminous family, lasts from
twenty to thirty years, according as the soil is more or
less favourable to it.
Emily.—It is then too long lived to enter into a course
of cropping 1
MRs. B.-In some parts of the valley of the Rhine,
these courses are made of thirty years’ duration, twenty
of which is occupied by lucerne. The roots of this plant
strike twelve or eighteen feet into the soil; a depth at
which moisture is always found, so that lucerne is enabled
to resist drought much better than clover, whose roots
are more superficial. Yet, if the season be dry, there is
some danger of its failing the first year of its growth, the
roots not having reached a depth of soil which is always
moist. The seed for sowing should be chosen of a bright
yellow colour, and heavy; a caution necessary to be at-
tended to, in the choice of all seeds. Lucerne is mowed
from three or four, to seven or eight times in the year,
according to the climate in which it grows. Its herbage is
less delicate than that of saintfoin,
CARoline.—Have we not seen lucerne growing as a
shrub in some parts of Italy
Mrs. B.-This is of a different species; it is naturally
a shrub, and grows wild on the sea-coast in Italy, where
it is used as fodder for cattle. Furze may also be culti-
wated, either as a shrub or as artificial grass. In the lat-
ter, state, it should be mown very young, while still soft
and tender; after growing three years it is rooted up, but
it prepares the soil admirably for grain.
There is some artificial grasses which are not legumi.
nous; Burnet is of the family of Rosaceae : it has the ad-
vantage of thriving in calcareous soils.
The wild endive, and, indeed, the leaves of almost any
plant, are susceptible of being cultivated for forage; ex-
cepting those which have either milky or astringent
328 CULTIVATION OF GRASSES,
juices, such as the leaves of the fig, or the oak: cattle
will not eat them ; or at least not unless they are mixed
with a considerable portion of good forage. But without
cultivating them as grasses, the young leaves of the ash,
the willow, and the acasia, gathered from the tree, make
very wholesome food for cattle.
EMILY.—In Italy, the cattle are very commonly fed on
the leaves of trees; and I have often observed, with ad-
miration, the industry of the Tuscan peasants, who col-
lect green weeds, the clippings of hedges, and the leaves
of trees, in order to supply their cattle with food.
MRs. B.-The small size of the Tuscan farms, which
seldom exceed fourteen acres, do not admit of meadow
land, excepting the grass walks with which they are in-
tersected. The nearer we approach the tropical cli-
mates, the more we find meadows, both natural and arti-
ficial diminish : the climate becomes too hot and dry for
the cultivation of grasses.
We have observed, that there are some species of
plants which afford food, both to men and cattle. These
are the class of tuberous roots, which constitute one of
the most valuable gifts of nature.The potato, the turnip,
beet, and carrot, all belong to this class. Were these
vegetables cultivated only in quantities sufficient to sup.
ply the wants of the human species, they would be con-
sidered as a most valuable acquisition, by varying, in a
salutary and palatable manner our stock of vegetable
food. But when produced in such abundance that it is
applied also to the sustenance of cattle, it not only ex-
tends the benefit to a lower order of beings, but furnishes,
in case of need, a store of food for man; the accidents
which injure the crops of corn being seldom hurtful to
tuberous roots.

CARoll NE.-And, should both fail, we have the re-
source of feeding on the cattle, who are themselves de-
prived of food.
ExIILY.—It is this, no doubt, which explains what ap-
peared to me very unaccountable, that meat is some,
times cheap, when bread is dear,
TUBEROUS ROOTS, AND GRAIN. 329

MEs. B.—If forage fail, whether it be owing to a
scarcity of grasses or of roots, a great number of cattle
will be sent to market, and the meat will eonsequently
be low priced, but it will be of inferior quality; for, un-
der such circumstances, the cattle cannot be fattened.
The culture of tuberous roots require very deep
ploughing. Beet is of various colours, most commonly
of a rich crimson. It is raised from seed, and the young
plants afterwards thinned : the soil should be neither very
moist nor very dry: the seed ripens only the second year.
This plant contains so great a quantity of saccharine
matter, that, during the prohibitory system of Buonaparte,
the French had recourse to it for the fabrication of sugar.
Indeed, the manufacture is still carried on, and I under-
stand that some recently discovered mode of facilitating
the process enables them to compete with the West In.
dia market. .
There are three species of turnips;–turnips, Sweedish
turnips, and the Kohl Rabi, or turnip-rooted cabbage.
The leaves of the first are rough and hairy, those of the
second smooth, and those of the last form a medium be-
tween the other two, being hairy when young, and be:
coming smooth afterwards. There are many varieties of
turnips; the white are the most delicate, the yellow the
most robust: they require a light loose soil, and a good
deal of manure; for being of the cruciform family, which
contains azote, they must be furnished with the means of
obtaining this element, and it is animal matter which
yields it in greatest abundance.
The Topinambour, or Jerusalem artichoke, produces
a great number of tubers, which are much eaten in Eng-
land; but they are not relished on the Continent. This
plant is cultivated in some parts of America, and is
brought to Europe from the mountains of the Brazils.
Carrots require a light but not a loose soil : they are
rather of a delicate nature, suffering both from excess of
cold or of heat.
The potato, it is universally acknowledged, we derive
from America, but from what part is not well ascertained;
for it is remarkable that neither M. Humboldt, nor any
other traveller in that country, has met with it in its wild
330 CULTIVATION OF GRASSES,
state. Clusius, the first botanist who speaks of potatoes,
says that they were introduced into Europe by the Spa-
niards, in 1588. Sir Walter Raleigh brought them from
Virginia to England and Ireland, where their cultivation
succeeded much better, and they were more liked than
on the Continent of Europe; and it is we English, who
have subsequently been the means of introducing a taste
for them, into other countries.
EMILY.—In Italy the lower classes are still much pre-
judiced against potatoes, considering them as food fit
only for hogs and cattle.
MRs. B.-There are from one hundred to one hundred
and fifty varieties of this plant, which differ in colour,
form, precocity, &c. Potatoes are usually raised from
germs, contained within the tuber, and commonly called
eyes: these germs contain the rudiments of the young
plant, similar to the buds or the branches of a tree. In
order to make them sprout, the potato must be planted
cither entire or cut in pieces, leaving an eye in each
piece, from which the young plant shoots; or in case of
scarcity, the eye alone may be planted, reserving the
ſecula or mealy part for food.
EMILY.—I thought that the mealy part was a magazine
of food for young plants which shoot from these germs,
and was, therefore, necessary to their development.
MRs. B.—That is true ; and the plant will shoot with
much more vigour if the ſecula remain attached to it; it
is not, however, absolutely necessary: for the eye, if
planted naked, has the power of absorbing moisture on
which it feeds, till it has struck out roots, which supply it
more regularly with nourishment. Potatoes may also be
raised from slips, and as a last resource the seed may be
sown ; but this is so slow a process, that it is resorted to
only with a view of procuring new varieties. Though the
potato bears the name of tuberous root, the bulb does not
grow upon the root of the plant but on the lower branches,
which bury themselves under ground: in cultivating the
potato, it is necessary to hoe up the earth over these
branches, in order to cover them more completely.
There is a small tubercle produced by the potato-plant
TUBEROUS ROOTS, AND GRAIN. 3.31
at the axillá of the leaf, which being exposed to the light
becomes green, and is of so acrid a nature as not to be
eatable. Half the weight of the potato consists in fecula:
the saccharine principle may be developed in this turber-
cle as it is in barley; it will not produce wine, but spirit
may be distilled from it when fermented; and the residue
affords excellent food to fatten hogs. The other half of
the potato consists in fibrin and mucilage. From eight
to ten pounds weight of potatoes per day is a proper
quantity to give to cattle when there is a sufficiency of
hay to mix with it; but, in case of a scarcity of the latter,
they will consume from eighteen to twenty pounds of
potatoes without inconvenience.
We may now proceed to the examination of one of the
most important of the vegetable productions in civilised
countries,<-I mean corn. We have hitherto considered
gramineous plants as cultivated only for their leaves,
under the name of grasses : but there are many of this
family whose seeds are large enough to afford food for
man, and it is with this view that he cultivates them.
These are distinguished by the name of grain or corn, in
Latin Cerealia, from Ceres the goddess of plenty, who is
said to have first introduced corn into Sicily; but whence
it originally came is unknown, it having never been found
growing in a wild state. Some naturalists are of opinion
that we derive grain from the mountains of Persia and
Thibet; a species of wheat, the Triticum Spelta, com-
monly called Spelt, having been found growing wild in
those countries. Others derive its origin from Tartary.
As corn belongs to the class of monocotyledons, the
stems have no bark; but these tall and slender stalks
derive their stability from a quantity of silex, which, not
being of a volatile nature, is deposited on the surface of
the straw or culm, when the more volatile parts evaporate.
Here it accumulates, and in the course of time encloses
the straw in a species of coat of mail, which not only
enables it to resist injury, but also to support the weight
of seed it has to bear.
EMILY.—Were it not for this provident supply of
Nature, it is true that a elenº; hollow straw would be
&
332 CULTIVATION OF GRASSEs,
quite uncºual to support the burden of a heavy ear of
COI’Ile
Mrs. B.-In this and all northern countries, the straw
is generally hollow; but in warm climates it is full.
The stems of gramineous plants are also intersected with
knots or articulations, designed no doubt to add to its
strength; and each of these shoots out a long slender
leaf, which encloses the stem like a sheath.
Grain constitutes the fruit of corn, and consists,
consequently, of the seed and its pericarp : these are so
closely attached together, that they are not easily separa-
ted or distinguished from each other, when in the state of
grain; but when ground into flour, it is the pericarp
which forms the coarse bran; and the seed, the flour
used for common household bread.
EMILY.—This flour then consists of the contents of the
seed, together with its spermoderm; and it is, no doubt,
the latter which renders it brown.
MRs. B.-You are right: in order to obtain the whitest
wheaten flour, such as the bread in London is made of,
the spermoderm, which forms a finer species of bran,
must also be subtracted: all this is very adroitly per-
formed by that skilful naturalist the miller, with his sieve
of bolting cloth.
EMILY.—How admirably this seed is protected it is
true that it is one of great importance to mankind: but is
it not curious to think, that so small a body as a grain of
corn should have two coverings, consisting cach of three
coats?
CARoline.—And the husk, besides, for an outer gar-
ment. I thought it had been the husk which formed the
bran.
MRs. B.-No, my dear; the husk constitutes the chaft,
which is separated from the grain by the operation of
thrashing. &
It is only in one species of corn, the Triticum Spelta,
which I have just mentioned, that the husk adheres so
firmly to the grain as to require a peculiar process of
grinding, in order to part them. This renders it less
TUBEltous ROOTS, AND GRAIN. 333
liable to the depredations of the feathered tribe, who can
easily pick out the naked grains of wheat from the ear;
but find it very difficult to dislodge those of epotre from
the adherent husk.
The seed contains the embryo plant, and the albumen,
which is to afford it the first nourishment, and this we
have already said consists of fecula and gluten.
CARollsa.-Since the albumen supplies so ample a
provision for the young plant, the cotyledon of corn is not,
I suppose, of a succulent nature.
Mrs. B.-I beg your pardon; but it is so minute as to
afford but very little sustenance.
The beard of corn is formed by the prolongation of the
husks; it is not improbable that all species of grain was
originally bearded, and that many of them lose this
appendage when cultivated in good soil.
CARo1.1NE.—The beard then, I dare say, is the result
of a degenerated organ, like thorns or tendrils.
MRs. B.—Very likely; or at least that in a state of
cultivation it disappears. Of the two species, bearded
corn is by far the more robust; but it has the inconve-
nience of being subject to retain moisture, so that in a
wet summer it is much more liable to injury.
Grain may be divided into three series:
First. That whose flowers have both pistils and sta-
mens, and are aggregated in the form of ears.
Second. That with similar flowers, but in the form of
clusters or bunches.
Third. That in which the pistils and stamens are
situated in different flowers.
In the first series, which comprehends wheat, barley,
and rye, there are slits or cavities along the axis of the
ear, whence issue smaller ears or earlets: in the spring,
these put forth a little flower and sometimes several, each
of which contains a single grain, enclosed in a husk;
these form the aggregated ear. The flowers have three
stamens, and one pistil with two stigmas. The grain of
wheat is of an oval form, that of epotres, rather triangular.
EMILY.—Is not the wheat sown in autumn more hardy
than that which is sown in spring 7
J34 CULTIVATION OF GRASSES,
MRs. B.-There is no difference in them whatever,
excepting that the former ripens earlier.
The largest grains of corn should always be selected
for sowing, because the pericarp does not increase in
size in proportion to the seed.
It is the gluten contained in the grain of wheat which
produces the fermentation of bread : this process is
vulgarly called raising the bread; and it is true that the
disengagement of carbonic acid, which takes place during
fermentation, actually raises the dough, producing those
hollow interstices which render bread light and digestible.
Other species of corn do not make such good bread, as
they contain less gluten.
Exſily.—I recollect, during a scarcity, potatoes being
mixed with wheaten flour to make bread ; but it rendered
it very heavy and unpalatable.
CARoline.—I thought that yest, the produce of the
fermentation of beer, was commonly used to excite that
of bread.
MRs. B.-It is so in England; but it acts merely as a
stimulus to hasten that of the gluten. On the Continent,
and in wine countries in general, where beer is little
drank, the fermentation is excited by means of leaven,
which consists of a piece of dough which has been kept
from a former batch of baking, and has turned sour; or,
chemically speaking, undergone the acetous fermentation.
Now there is so much analogy between the acetous
fermentation and that of bread, that it is sufficient to
place a body which is undergoing, or has recently under-
gone the former, in contact with dough, to excite it to
ferment, and this may be done either with yest or leaven.
CARoline.-It is then a sort of contagion which these
bodies communicate to the dough; but is it not surprising
that it should render the bread light and wholesome,
instead of turning it sour?
MRs. B.-Were the fermentation of the dough not
interrupted by baking, it would become sour, as that
portion does which is reserved for leaven. The fermen.
tation of bread is by some chemists considered as a
commencement of the acetous fermentation. There
TUBEROUS ROOTS, AND GltAIN. 335
must however, I conceive, be some difference between
these processes, as in the regular succession of fermenta-
tions, the acetous is always subsequent to the vinous;
and bread is so perfectly insipid, that there is no reason
to suppose it has undergone the latter.
EMILY.—Yet wheat is, I suppose, like other kinds
of grain, susceptible of undergoing the vinous fermenta-
tion.
MRs. B.—Certainly ; alcohol may be obtained from all
kinds of grain. There are four species of wheat.
First. The common wheat, whose ears are erect, and
its grains opaque and obtuse.
Second. The Triticum turgidum of Limoges, which
the French call Gros bled, whose ears are thicker and
larger; it contains less gluten, and, consequently, is not
so well calculated for bread; but is much used on the
Continent to thicken soup or porridge. This wheat, if
cultivated in a very rich soil, produces a variety called
miraculous wheat, the ears which are branching from the
abundance of their produce.
Third. Bled dur, or hard wheat: the grain is semi-
transparent; it has still less gluten than the preceding :
it is of this species that macaroni, vermicelli, and all the
Italian pastes are made : it requires a dry soil and a warm
climate, and thrives best in the southern parts of Europe.
Fourth. Polish wheat: it grows very plentifully in
Poland, and is thence exported to other countries ; but
being of inferior quality, it is little cultivated elsewhere.
Spelt contains less gluten than other species of wheat:
it affords beautifully white flour for pastry, and is also
much used for starch.
ExIILY.—I should have thought that it would have re-
quired more gluten to make starch than to make bread 7
Mas. B.-No; starch consists almost wholly of pure
fecula, and may be obtained from potatoes as well as
from wheaten flour.
Rye is of so hardy a nature that it accommodates itself
to almost all soils and all climates: its straw is longer
and firmer than that of wheat, which renders it peculiarly
adapted to thatching : it contains so little gluten that it

29*
J35 CULTIVATION OF GRASSES.
cannot be made into bread without an admixture of wheat.
ExIILy—It is, then, no doubt, on this account that the
poor Scotch Highlanders, who cannot afford to mix
wheaten flour with it, eat it baked in cakes instead of
bread.
MRs. B.-It is chiefly oats, I believe, that are thus eaten
in Scotland.
Barley is principally used for fermentation. It con-
tains a great quantity of saccharine matter: mixed with
hops we have seen that it produces beer; and it is also
distilled for spirits.
In the second series of corn, the grain grows in the
form of clusters, each earlet having a separate pedicle or
footstalk.
This series contains four genera.
First. Oats: the husks or glumes have two valves and
beards springing from the back part of the husk, instead
of growing from the summit, as with barley and rye.
Oats afford food both for man and for horses.
Second. A species of oats derived from Asia, the ear-
lets of which incline all in one direction : it is more
robust than the preceding, yet it is very liable to be at-
tacked by the disease called smut.
Third. The Phalaris of the Canary Isles, commonly
called Canary seed, used chiefly as food for the birds,
for which those islands are so celebrated.
Fourth genus. Rice, which we derive both from the
East and West Indies. Next to the Banana or bread
tree, this is the plant which affords the greatest quantity
of wholesome nourishment, and is, perhaps, susceptible of
the greatest variety in the mode of cooking; for being
itself insipid, it admits of all kinds of seasoning.
ExIILY.—How much, then, it is to be lamented that its
cultivation should be unwholesome !
MRs. B.-It is so only at that period when the water is
drawn off to enable the grain to ripen. It is sown in the
spring in a muddy soil; and as the plant grows, the water
is let on, and gradually raised so as to keep it almost
wholly covered, until the grain begins to ripen. I have
been informed that in the rice plantations of Lombardy,
TUBEROUS ROOTS, AND GRAIN. 337
the mortality is not greater than in the adjacent districts:
it is true that the inhabitants of the latter are in a wretched
state of poverty, while the cultivators of rice are at least
supplied with plentiful nourishment, to compensate for the
unwholesomeness of their occupation. I should not wish
to extend the culture of rice in Europe, in soils adapted
to other produce, but, as this plant will grow only in
marshy districts, it is as well to convert such land to so
useful a purpose ; for it is not more unhealthy as rice-
fields, than as marshes. One great objection to the cul-
tivation of rice is, that it injures the surrounding soil by
the filtration of the waters, which, in the course of time,
destroys all the trees in the neighbourhood.
CARolin E.-But such a filtration must be very advan-
tageous to meadow land 7
MRs. B.--When confined within due limits ; but we
must remember the old adage, “Too much of a good
thing is good for nothing :” but the adjoining meadows
would eventually become converted into marshes, so that
there would be no other resource than to extend the culti-
vation of rice; and the evil would thus always go on in-
creasing, if government did not interfere to prevent it.
The third series of corn, having the pistils and stamens
in different flowers, consist of maize or Indian corn,
Canada rice, Sorghum, or millet.
We have run through a great variety of subjects to-
day; the natural and artificial grasses, which form the
two great stores of food for cattle, and the latter of which
enters so beneficially into the rotation of cropping; the
tuberous roots of which both man and beast equally par-
take : and, finally, the numerous species of grain, which
afford a more solid and wholesome nourishment than any
other kind of vegetable food. After such an abundant
store of sustenance, were I to prolong the subject further
I fear it would satiate your appetite, we will therefore
reserve what remains to be said on vegetable food till
our next interview.
333 ON OLEAGINOUS PLANTS,
CONVERSATION XXXI.
ON OLEAGINOUS PLANTS, AND CULINARY
VEGETABLES.
MRs. B.-Among the articles of vegetable food, the
oils which are extracted from plants afford one of the
most valuable ; nor are they of less importance in afford-
ing us light by their combustion. They are employed
also in a number of manufactures, such as soap, woollens,
varnishes, and perfumery.
There are, you know, two kinds of vegetable oil, dis.
tinguished by the name of fixed and volatile. The latter
may be extracted from almost every plant ; but it is
used only as a perfume, or to flavour liqueurs, such as the
ottar of roses, with which you are acquainted.
EMILY.—Yes; and with that of jassamine and orange,
so commonly used to perfume pomatum. In a word, the
perfumer's shop abounds with these sweet scented oils.
MRs. B.-They constitute the luxury of the sense of
smelling, but are frequently prejudicial from their effect
on the nerves; and some few of them are employed me.
dicinally. But the essential or volatile oils are not those
most deserving our attention: the fixed oils are of much
higher importance, and are extracted from a class of
plants, hence called oleaginous. The oil is expressed
from the seed of all these plants excepting the olive, in
which it is obtained from the pericarp, or fleshy part of
the fruit which surrounds the seed.
The greater part of the seeds of oleaginous plants
contain albumen, and it is from this, that the oil is ob-
tained; but when the seed has no albumen, as is the case
with the poppy, it is the embryo which furnishes the oil.
In the family of the Euphorbiaceae, all of which have
oleaginous seeds, the embryo is of a venomous nature,
and oil extracted from it would be poisonous; while that
expressed from the albumen of the same plant, situated
contiguous to the embryo, is perfectly innocent. Such
is Banculnut, (Aleurites Moluccanum,) which is remark-
ably mild, and is eaten by the inhabitants of the Molucca
AND CULINARY VEGETABLES, 339
isles, as we eat hedge-nuts in Europe, while oil obtained
from the embryo is an acrid poison.
ExILY.-Can oil be expressed from plants growing
wild, or is it necessary they should be cultivated in or-
der to supply it?
MRs. B.-Some small quantity may be obtained from
thistles: the stone pine and plum-tree of Briancon also
yield it; but it is the seed of the beech-tree alone which
affords it in sufficient abundance to make it worth the la-
bour of obtaining. The forest of Villers-Coterot, in
France, produces a great quantity of this oil. It is less
liable to become rancid than any other, and, on this ac-
count, is often mixed with olive oil, which is to be ex-
ported to America or any other distant part ; but it all
passes under the name of olive oil.
The fixed oils obtained by cultivation may be ranged
under three heads; first, olive oil, the produce of warm
climates; secondly, nut oil, that of temperate climates;
and, thirdly, oils obtained from the seeds of oleaginous
herbs.
The olive-tree originally came from Syria. That
plant, as well as the vine, was brought to Marseilles by
the Phocians; and, at the present day, it is cultivated on
all the shores of the Mediterranean. It is a tree of very
slow growth, but of long duration: it can support a tem-
perature as low as eight or ten degrees of Fahrenheit,
provided the air be dry; but, if accompanied with hu-
midity, one or two degrees below the freezing point,
proves fatal. The plant, however, may recover, if cut
down to the roots, a little below the surface of the soil;
it then strikes out fresh roots, forming five or six young
trees.
Manure used for olive-plantations should be of a dry
nature; and it is necessary to heap up the earth over the
roots, to keep them well covered.
CARoll NE,--These roots must be naturally very su.
perficial; for, notwithstanding the care that is taken to
cover them with earth, I have observed that they are con-
tinually making their appearance above ground.
Mrs. B.—It is rather the rugged and tortuous base of
340 ON OLEAGINOUS PLANTS,
the stems which you have observed, and which wear the
appearance of roots.
There are several varieties of olive-trees. Those of
the plantations about Nice, afford us oil perfectly white
and limpid, and equally free from either smell or taste :
it is held in very high estimation in northern countries,
where the natural taste of oil is disliked, probably from
its being associated with that of rancidity; but, in the
countries which produce oil, where, being eaten fresh, it
is very seldom rancid, the oil which partakes of the fla-
vour of the fruit is preferred.
The fruit should be gathered, not shaken from the tree,
in order to prevent their being bruised, and the oil ex-
pressed as soon as possible afterwards, otherwise there is
danger of rancidity. In Spain, and other countries
where feudal tenures still exist, the olive-mills belong to
the lords of the land, and the peasantry are obliged to
wait their turn for their olives to be pressed, to the great
detriment of the produce. This is, perhaps, the only
harvest which is gathered in about Christmas, the fruit
not being ripe earlier.
Olives begin to be cultivated at 43° of latitude : in tro-
pical climates, they will grow at two hundred fathom
above the level of the sea.
EMILY.—And, in temperate climates, where the olive
ceases to grow, the walnut replaces it.
MRs. B.-Yes; but the oil obtained from the walnut is
far inferior to that of the olive, having both colour, smell,
and flavour, qualities which are not esteemed in oils.
The walnut-tree succeeds better in a northern than south-
ern aspect; for, as the young shoots are very liable to
suffer from a white frost, it is desirable that their vegeta-
tions should be retarded till the spring is so far advanced,
that there will be little danger of their encountering that
evil. This tree grows remarkable well at the foot of a
mountain, on account of the depth of soil produced by the
quantity of earth washed down.
The cultivation of oleaginous herbs enters into the
course of cropping : they exhaust the soil almost as
much as grain, on account of the number of seeds to be
AND CULINARY VEGETABLES. 341
ripened; they require, therefore, a considerable quantity
of manure. These herbs are generally of the cruciform
family, containing azote, an element of the animal king-
dom which forms excellent manure : so that, aſter the
oil is expressed, the cake which remains serves to re-
store the exhausted soil. Rape is a species of cabbage
with thin roots, whose seeds will yield excellent oil.
The poppy is an oleaginous plant, with white, scarlet,
and violet flowers, while the seeds are white or black.
They yield oil, perfectly innoxious and wholesome,
though drawn from the same plant which supplies us
with opium.
CARol.INE.-I confess I should always be apprehensive
of its being adulterated with some mixture of its poison-
ous neighbour. Is not flax, also, an oleaginous herb 1
Mrs. B.-Yes. It is, however, chiefly cultivated for
its stalks, from which linen thread is fabricated ; but its
seed also yields the oil which we call linseed-oil. It is
much used in the art of painting. Hemp is of the same
description. There are some few oleaginous herbs of
the leguminous family, such as the subterranean (Arachis
hypogaea,) a plant we derive from America, which has
the singular property of ripening its seeds under ground.
This plant requires a loose sandy soil, in order that the
lower branches may be enabled to bury themselves in the
ground. In a state of cultivation, the earth should be
heaped over them, as is done with potatoes. The upper
branches, which blossom in the air, ripen no seed; while
the lower branches, which burrow in the earth, develope
no regular blossom, that is to say, have no petals; but the
stamens and pistils bring the seeds to perfection.
Among the objects of cultivation, the vegetables raised
in our gardens for culinary purposes form a class of con-
siderable interest.
CARo1.INE.-In our choice of these, we must be regu-
lated by the palate.
MRs. B.-Principally, do doubt; but modified by other
circumstances, such as soil, climate, &c. Plants of a
fibrous woody nature are too tough to be either palatable
or digestible. Those which are acrid, or very bitter,
342 ON OLEAGINOUS PLANTS,
must be equally rejected. A powerful flavour is also
objectionable; and, on the other hand, great insipidity will
not gratify the palate. Here, then, are many causes of
exclusion, but some of them admit of remedy.
Plants of an acrid nature may be eaten young, before
the acridity is well developed, especially if the most deli-
cate parts be chosen, which are those that have been
least exposed to the light. Thus the receptacle, or what
is commonly called the bottom of the artichoke, and the
internal part of the bractea, are mild and pleasant to the
taste when young.
EMILY.—And asparagus we eat as soon as the young
shoots appear above ground.
CARolin E.-And do we not even find the taste of rhu-
barb in tarts delicate and pleasant, when the plant is very
young, while, when full grown, it is so repugnant to us?
MRs. B.—It is true that rhubarb requires to be eaten
very young, in order to be palatable ; but it is the ribs of
the leaves which we make into tarts, while that part of
the plant taken medicinally, and which is so pungent and
disagreeable, is the roots; and it must grow in a warmer
climate to have its medicinal properties developed. That
which we import from Turkey is grown either in Tartary
or at the foot of Mount Caucasus.
All strong vegetable flavours, even that of the Prussic
acid, which is one of our most deadly poisons, may be
rendered agreeable to the palate, and perfectly innocent,
if taken in very minute portions, and mixed up with con-
siderable quantities of insipid food. The Prussic acid is
found in the kernels of peach-stones and in bitter al-
monds, but in very small quantities; and yet one or two
of these is sufficient to communicate an exquisite flavour
to a dish of cream or of pudding.
Celery belongs to the class of Conium, or hemlock,
the poison which caused the death of Socrates; but its
pernicious qualities will not be developed, and it will
grow white and tender, if the stems be kept covered with
earth.
EMILY.-Insipid plants should, then, on the contrary,
be fully exposed to the light and air, in order to bring
forth what little flavour they contain
AND CULINARY VEGETABLES. 343
MRs. B.-Yes; and they should be eaten only when
full grown. Great insipidity is not wholesome, any more
than a very strong flavour; the one produces too great
excitement in the digestive organs, the other does not
afford them sufficient stimulus.
EMILY.—Both these defects, I should think, might be
corrected, by cooking vegetables of such opposite quali-
ties together.
MRs. B.-It is with this view that thyme, sage, mus-
tard, onion, and even garlic, are used as seasoning for
food of an insipid nature; and sugar and spices are most
useful auxiliaries for such a purpose.
CARoline.—Salt seems to be the most universal of
all ingredients to season cookery.
MRs. B.-I omitted mentioning it, because it was not
of the vegetable kingdom.
There are no less than fifty-four species of plants,
which may be considered as belonging to the class of
culinary vegetables. These are derived from thirty-nine
genera and seventeen families; and produce above five
hundred varieties.
Among these families, the Cruciform supplies our table
with the greatest number of dishes. It derives its name
from the blossom having four petals in the form of a cross.
Azote is found in this family alone, and it communicates
to the vegetables a strong flavour, and often an offensive
smell. The various species of cabbages belong to it,
such as the common cabbage, the curled cabbage, broc-
coli, cauliflowers, turnips, radishes, water-cresses, and
sea-kale.
CARoline.--Do you include turnips and radishes
among the species of cabbages 7
MRs. B.—Their leaves and blossoms are of the same
description; but the appearance of the vegetables on the
table, I confess, is totally different; and no wonder, for
in the one it is the leaves we eat, in the two others the
TOOts.
CARolin E.-The leaves of the turnip, it is true, would
be too strong and pungent for our palate. They are
30
344 ON OLEAGINOUS PLANTS,
relished by sheep and cattle ; and the root, which is
more delicate from not being exposed to the light, is
better suited to our taste.
Exirly.—The roots of radishes are, however, so
strongly flavoured, as to be disagreeable, unless eaten
very young. In the cauliflower it is the blossom, and not
the leaves, that we eat.
MRs. B.-The head of a cauliflower has, it is true,
much the appearance of a blossom, but it consists only of
numerous ramifications of the peduncles, or flower-stalks,
which not having sufficient space to grow in, adhere to-
gether, and form the white mass which we esteem as a
very favonrite dish of vegetable food.
EMILY.—But the cauliflower is rather of an insipid
than of a pungent nature, and requires salt to season it.
Mrs. B.—Its flavour is not strong if the head only be
eaten; but the smell and taste of the water in which it is
boiled is extremely offensive, and that of the vegetable
itself is often unpleasant, when served at table.
EMILY.—I know scarcely any odour more disagreea.
ble than that proceeding from a plantation of decayed
cabbages, in which the azote is fully developed.
MRs. B.-When the cauliflower is allowed to attain its
natural growth, or, as the gardeners express it, is left to
run to seed, the flower-stalks lengthen and spread, and
the blossoms are developed at their extremities. Broc.
coli is of a similar nature: the pedunculi amalgamate and
form a head; but it is of a green colour, because not so
closely enveloped in leaves and sheltered from the light
as the cauliflower. The small tender grain which is depo-
isted upon it, consists of the embryo of blossoms which
cannot be developed, owing to the quantity of nourish-
ment of which the stalks deprive them.
The Leguminous family affords us four species of culi-
nary vegetables, peas, beans, lentiles, and kidney-
beans; of some of these we eat only the seeds; in
others, such as the kidney-bean and sugar-pea, the pod or
pericarp are also eaten.
The family of Cucurbitaceae supplies us with cucum.
bers, pumpkins, and melons: the two first are rather arbi-
AND CULINARY VEGETABLES. 315
trarily denied the name of fruit, and are ranked as culi-
nary vegetables, merely on account of the saccharine
principle not being developed in them.
This family is distinguished by a bitter principle con-
tained in one of its species, the Colocinth; it is so strong
as to be taken only medicinally.
From the Umbelliferous family we obtain carrots, pars.
ley, lettuces, and hemlock. The narcotic principle exists
throughout this family: in hemlock it is so powerful as
to constitute a poison; but in most of the other species,
it exists in such small quantities as not to be deleterious.
The family of Solanum gives us the Potato Tomata,
and the Belladonna, celebrated for the poison it contains.
CARoline.—And yet nearly akin to the potato, which
is of so innocent a nature
MRs. B.-That is true of the tubercle we eat, but the
fruit of the plant is of an acrid nature: you may proba-
bly have been warned, in your childhood of the poisonous
properties of the small green tubercles which grow on
the branches.
The family of Fungi supplies us with the mushroom, a
vegetable of a most delicate and exquisite flavour; but as
those species which grow wild are generally of a poison-
ous quality, it is important that we should learn how to
produce such as are known to be innoxious. For this
purpose, the white filaments, commonly called the spawn
of mushrooms, should be cut in pieces and sown in a hot-
bed. Whether these filaments consist of shoots, runners,
or seeds of mushrooms, has not been well ascertained;
but when spread over a hot-bed, and sheltered from the
open air, either under a shed or in a cellar, they will
germinate. . In Paris, mushrooms are raised in the Cata-
combs; and I know no place where they are produced
in such abundance, or sold so cheap. The spawn should
be sown in December, covered with a little earth and a
litter of straw, then watered ; and after a short time, if
the litter be raised, the mushrooms will be seen growing
beneath it.
These are some of the principal families from which
we derive our vegetable food : I will not attempt to go
346 ON OLEAGINOUS PLANTS, ETC.
through the whole seventeen, it would be uselessly tres.
passing upon your patience.
I have now, I believe, imparted to you the whole of
my little stock of botanical knowledge. The source from
which I drew it was rich and copious; but I am too well
ware of my incapacity to do justice to the subject, not to
j at the apprehension of having disfigured those
lessons which afforded me such a delightful source of
instruction; which taught me to investigate, with wonder
and admiration, the beautiful organisation of the vegeta-
ble creation, and raised my mind, with increased fervour
of gratitude, towards their bountiful Author.
INDEXe
A.
Abrupt root, 31.
Absorption § the roots, 25.
Acacia, 62, 146, 280.
Achenium, 56, 210.
Acotyledons, 37, 262.
Adamson, 146.
AEsculus ºf; xcastanum, 224.
Aggregated fruits, 56, 223.
Air, 104, 115, 121, 285.
Albumen, 338.
Alburnum, 42, 83.
Aleurites moluccanum, 338.
Almond, 217.
Amendements, 153, 157.
Amnios, 226.
Annular section, 81.
Annuals, 167, 270.
Anthers, 198, 211, 279.
Anthoxanthum, 324.
Apocinum, 201, 218.
Apple, 218, 220.
Apricot, 75, 313.
Aqueous plants, 185.
Arachis hypogae, 241:
Artichoke, 208, 212, 329.
Artificial grasses, 107, 168,326.
T2:...T systein of classification,
45.
Artocarpus incisa, 225.
Arum maculatum, 100.
Arundo arenaria, 147.
Ash, 306.
Ashes, 155.
Asparagus, 342.
Aspen, 63, 173, 306.
Assolements, 162.
, simultaneous, 174, 177.
, successive, 174, 177.
Atmosphere, 105.
Aurantiaceae, 268.
Avenues, 304.
Azote, 84, 329.
B.
Bacca or berry, 222.
Bancul nut, 338.
Barberry, 312.
Bark, 23, 44, 121, 287.
Barley, 315, 336.
Bean, 226.
Bearded corn, 333.
Beech, 302, 339.
Beet, 328.
Balladonna, 13, 345.
Birch, 119,306, 314.
Bloom of fruits, 90.
Blossom, 49, 279.
Botanical geography, 264.
regions, 266.
Bran, 332.
Branch, 25.
Branches, 180, 186.
Brandy, 315.
Bractea, 55.
Bread, 334.
Bread-tree, 225.
Broccoli, 343, 344.
Broom, 146, 147, 174.
Bryophyllum, 214.
Buck-wheat, 169.
Buds, 57, 194, 277.
Bulbous root, 31, 38,79.
Burnet, 327.

C.
Cabbages, 96, 343.
Cacti,268, 279, 290.
Calendar of Flora, 201.
30*
348
INDEX.
Calyx, 195, 209,220.
Cambium, 77, 182, 287.
Campine, 146
Canada rice, 337.
Caoutchouc, 86.
Capsular fruits, 225.
Carbon, 72, 82, 103, 285.
Carbonic acid, 92, 103, 154, 157.
Cardoons, 96.
5.º %
& 198, te
§. 328.
Castaneavesca, 224.
Cattle, 169.
Cauliflower, 343, 344.
Celery, 96, 342.
Cellular system, 21, 40, 44.
Cereala, 269.
Chafi, 208.
Charcoal, 159.
Cherry, 313.
Chesnut, 43,224.
China-Aster, 51, 206.
Cider, 315.
Chinchona, 268.
C ºncation of plants, 91, 239,
253.
artificial systems of 245.
natural †. 254. f
Limnaeus', 249.
Climate, 105.
Clover, 172, 326.
Cochineal, 290.
ſocoa-nut, 39, 59.
Colmare, 139.
Colocinth, 345.
Coloured leaves, 55.
Colours of plants, 92, 274.
Columella, 220
(Yoma, 210.
Combler, 139.
Compound leaves, 52.
Compound flowers, 206.
Cone, 223.
Conium, 342,
Contractability, 18.
Copal, 87.
Core, 221.
Cork, 45.
Corn, 38, 169.
-, beard of, 333.
—, series f jº,
— ears o
—, flowers of 333.
Corolla, 196, 211.
Cortical, 40
3. *,54.
uch-grass, 29.
Cow-tree, 86.
gus crusyalli, 312.
Qreeping plants, 291.
Cruciform, 343.
Cryptogamous plants, 181
Cucumbers, 344.
$. tº."
Tulinary vegetables, 341.
Culm, %. get
Cuscuta, 194.
Cuticle, 23, 45, 226,
Cyme, 201.
Cyneps, 289.

D.
Dactylis, 324.
Dahlias, 59.
Date-tree, 37.59.
#. . 63. 2
aeration of organs, 278.
Dehiscence, 214.
Dehiscent, 225.
Delta, 141.
Dew, 128.
Dicotyledons, 36, 269.
Dionea muscipula, 19.
Diospyros, 313.
Diseases of plants, 278.
constitutional, 278.
from light, heat, water,
soil, &c. 278.
action of animals, 278
action of plants, 278,

— contusions, 289
Dissected leaves, 52.
Dodder, 294.
Dorsal rib, 51.
Down, 104.
Draining, 134.
in Holland, 136
marshes, 136
Pontine, 136.
Tuscany, 137
Drosera, or sun-dew, 19
Drupe or Drupa, 217.
Ecobuage, 162.
Fiasticity, Ži, ii.5.
INDEX, 349
Elder,90. compound, 206, 207.
Electricity, 85. Flower, labiate, 212.
m, 305. radiate, 212.
Embryo shoot, 60. Folioles, 2H0.
plant, 226. Follicles, 218.
Endive, 96. Food of animals, 17, 25.
Endocarp, 215. — of vegetables, 17.
Endogenous plants, 36, 59, 262. Foot-stalk, 38.
Endopeura, 226. Forests, 300.
Epacrideae, 268.
Epicarp, 215.
Epidermis, 24, 46, 105.
Epilolimus, 210.
Ergot, 296.
Eringium, 207.
Erisiphe, 294.
£º, 277.
Essential oils, 86, 88.
Etiolation, 97.
Euphorbiaceae, 261, 338.
Evergreens, 63, 189.
Exogenous, 36, 262.
Exudation of plants, 91, 164, 172.
Eye of a plant, 61, 187.
— of a fruit, 220.
F.
Families of plants, 244, 261,263.
Farm, 169.
—, Belgian, 169, 177.
—, English, 170, 172.
—, Rhenish, 174.
——, French, 172, 175.
—, Italian, 176.
—, Tuscan, 177.
Fermentation, 156, 314, 334.
Fermented liquors, 314.
Fibres, 23.
Fibrous root, 29.
Ficoideae, 261.
Fig-tree, 202, 289.
Filtration, 130, 131.
Fir, 56, 223, 300, 303.
Fixed oil, 88
Flora Scotica, 253.
— British, 263.
— Francoise, 274.
Floral leaves, 55.
Florets, 209, 211.
iigulate, 211.
tubular, 212.
Flour, 3';2.
Flower, 179, 195.
— bloom of 90.
—, tolerant, 300.
—, intolerant, 300.
, felling of, 301.
Fossil shells, 155.
Frankincense, 87.
Fraxinella, 88.
Freezing plants, 102.
Frost, white, 116.
Fruit, 50, 180, 213, 312.
trees, 204, 273,312.
stone, 234.
aggregated, 223.
capsular, 225.
dehiscent, 225.
buds, 58, 277.
Fuel, 301.
Fungi, 23, 37, 117, 290,294
Furrows, 150.


G.
Genera, 241,261,263, 343.
Geranium, 60.
Germs, 47, 60, 181, 226.
of stems, 180.
of roots, 181.
Gin, 315.
Glands, 86, 89.
Glumes, 336.
Gluten, 334.
Gorterias, 268.
Grafting, 182, 188.
, season for, 191.
, by approach, 192.
* by :. 193.
, by buds, 194.
Grain, 169, 315, 331.
Gramineous plants, 39,323.
Grasses, 322,324.
, artificial, 167, 326.
Green colour, 92.
cºlour, 108, 111, 123, 130,
Gum, 84, 87.
—— arabic, 87.
--- astragalus, 87.
350 INDEX.
Gum resins, 86, 87.
Gypsum, 155.
H.
Habitation of plants, 265.
Habits of plants, 20.
Hairs, 209, 211.
Hawthorn, 311.
Head of flowers, 206.
Heat, 68, 95, 99, 284.
Hedges, 310.
Hedysarum gyrans, 19.
Hemlock, 342, 345.
Hemp, 294, 341.
Hevea, 86. º
Hieracium pilossella, 271.
148
Hoe, * >
Hoed crops, 168.
Honey, 196.
Hornbeam, 193.
Horse-chesnut, 58, 107, 224, 304.
Horticulture, 130.
Hot-house, 108, 111, 123, 130.
Husk, 332, 336.
Hyacinth, 275.
Hybrid, 273.
#. 55, 83, 94.
Hydraulic rain, 132.
Hygrometric power, 21.
I & J.
Jerusalem artichoke, 329.
Jessamine, 40.
Ilex, 312.
Indian fig-tree, 32.
Inflorescence, 204.
Ink, 289.
Insects, 289.
Inundations, 140.
Involucrum, 200, 207.
Irrigation, 130.
Irritability, 18.
Ivy, 291.
K.
Kali or kelpwort, 116, 271.
Kalmia, 109.
Knotted root, 32.
L.
Labiate flowers, 212.
Lakes, 122.
Laurientius, 294.
Layers, 179, 182.
, season for, 185
Leaf-buds, 58.
Leaven, 334.
Leaves, 49, 213, 215.
, sessile, 50.
, articulated, 56.
—, fibres of 51.
—, ribs of, 51, 214.
—, stoma of 51.
, pennated, 51.
, palmated, 61.
—, peltate, 52.
—, pedatum, 52.
—, simple ribs, 62.
, contour of 52.
, pinnatifid, 52.
—, dissected, 52.
, compound, 62.
, succulent, 53.
—, seminal, 64.
, primordial, 55.
, radical, 55.
—, floral, 55.
, coloured, 55.
, arrangement of 56
—, folding of 62.
, deciduous, 63.
——, fall of 63, 84,286.
, variegated, 283.
Leguminous crops, 169
family, 344.
Lentiscus, 312.
Lettuces, 96, 345.
Liber, 80.
I.ichens, 23, 37, 117, 290
Light, 92, 96.
Ligneous, 40.
Ligulate florets, 211.
Liliaceous plants, 39
Lime, 64, 83, 154.
Linseed oil, 88.
#: of the *; $4
opping trees, 307.
#. 294,327
INDEX, 351
M. Odours, 88.
ambrosial, 89.
§. º, 83 : #sº
esia, º penetrating, 89.
§: isi, 223. stimulating, 89.
Maize, 134. sweet, 89.
Malaxis paludosa, 214. Oil, 84.
Malvaceous, 261. — cake, 158.
Mangrove, 183.
Manna, 86, 88.
Manure, 147, 150, 156.
, short, 159.
, long, 160.
Marl, 153.
Marsh, 134.
Mastic, 87.
Meadows, 324.
Medullary rays, 41.
Melons, 344.
Mesocarp, 215.
Mesosperina, 226.
Midrib, 51.
Milk, 86.
Millet, 337.
Mimosa, 18.
Mistletoe, 272.
Moisture, 116.
Monocotyledons, 36, 59, 262, 269.
Monopetals, 278.
Monstrosity, 278.
Mosses, 23, 117, 290.
Mulberry, 222.
Multiplication offººt. 179.
Muriate of soda, 116.
Mushrooms, 187, 345.
N.
Natural system of classification,
253, 254.
Naturalisation of plant, 105.
Neck of a plant, 35.
Nectar, 90, 196.
Nectarine, 313.
Nectary, 196.
Nettles, 89.
Nomenclature, 242.
Nut-oil, 88.
Nutrition, 15, 25.
O.
Oak, 173,293,297, 300, 302, 306.
ãº.”””
— of poppies, 341.
4 mEºs *ś, 86, 8R, 338.
— fixed, 86, 88, 338.
— olive, 88, 338, 339.
— walnut, 340.
Oleaginous plants, 338.
herbs, 340.
Oleander, 184.
Olive, 88, 108, 119.
Opium, 86, 341.
Opuntia, 313.
Orange, 108, 221, 313.
Orchis, 32.
Organs of plants, 17, 20, 85.
, structure of, 25, 242.
, degeneration of 278.
Orobanche, 294.
Orthoma, 207.
Ovary, 198, 209.
Oxygen, 73, 92, 103.
P.
Pabulum, 50,215.
Palinurus, 312.
Palm-tree, 37, 39, 59, 118.
Palmated, 61.
Pappus, 209.
Parasites, 290.
Parsley, 345.
Pasture, 299.
Pea, 214.
Peach, 104, 216, 313.
Pear, 220 $13.
peat earth, isł.
Peculiar juices, 77.
Pedatum, 52.
Pedicel, 38, 200.
;. e, ; 200,280.
Pelagra, 133. O
Pelargoniums, 268.
Peltate, 52.
Pennated, 51.
Perennials, 167, 296, 323.
Pericarp, 213, 215.
Perry, 316.
Perspiration of plants, 69.
352
INDEX.
Petals, 196,278, 279.
Petiole, 38, 51, 58.
Phalaris, 336.
Phillyrea, 43.
Phleum, 324.
Pickaxe, 148.
Pinks, 60.
Pine-apple, 56,224.
— tree, 147, 174.
Pinnatifid, 52.
Pistil, 198.
Pitch, 87.
Pith, 40.
Plains, 139.
Plane-tree, 33, 306.
Planting, 109.
Plough, 148.
Plum, 313.
Pod, 214.
Poeony. 59,218, 223.
tree, 220.
Pollarding, 288.
Pollen, 198.
Pome, 220.
Ponds, 122, 174.
Poplar, 87, 306.
Poppy, 219, 341.
Pores, 26.
Potamogretons, 271.
Potash, 64, 83.
Potato, 31, 187, 328, 345.
Prickles, 282.
Primordial leaves, 55.
Propagation of plants, 179.
Properties of plants, 21.
Pruning, #.
Prussic acid, 342.
Pseudosperma. 225.
Pumpkins, 344.
Putrefaction, 156.
Q.
Quick-lime, 154.
Quickset, 311,
Quince, 221.
R.
Racemus, 201.
Races, 263,272.
Radiate, 212.
Radiation of heat, 128.
Radical leaves, 55.
Radish, 30.
Radishes, 343.
Radix fibrosa, ;
repens, 29.
j. 3||.
racmorsa, 31.
ulbosa, 31.
tuberosa, 32.
Rain, 123, 126, 2H4.
Rape, 341.
Raspberry, 218, 222.
Receptacle, 200, 207.
Reeds, 60.
Regions, 264.
Resinous trees, 302.
Resins,
Rhizoctonia, 294.
Rhizomorpha, 292.
Rhizophora, 183.
Rhododendrons, 106, 109
Rhubarb, 342.
Rice, 336.
Rice-plantations, 133.
Ringing trees, b0, 203.
Rivers, 121, 140.
Robinia, 2-0.
Rocks, 143.
Roots, 25, 35, 191, 193.
duration of 33.
germs of 181.
Rosaceae, 313, 327.
Rose-tree, 295.
Rot, 295.
Rotation of crops, 161.
Rushes, 60.
Rust, 296.
Rye, 176,296, 335.
– grass, 324.
S.
Saffron, 294.
Saintfoin, 326.
Salicaria, 271.
Salicornia, or saltwort, 271
Salsify, 207.
Salsola, 116, 271.
Salts, 83.
Sand-hills, 146, 147.
Sands, 155.
Sap, 22, 64, 287, 314.
— rise of, 48.
— composition of, 65, 71.
— exhalation of 67.
— descent of 77.
INDEX.
353
Sap, velocity of 49, 65.
Sarmentaceae, 316.
Saxote, 271.
Scales, 58,
Scarzonera, 206.
Scions, 182, 185, 189, 193.
Sea-cale, 343.
Sea-salt, 117.
Secretions, internal, 86.
— excretory, 88.
Seed, 24, 118, 125, 143, 167, 179,
195, 197, 210, 224, 278, 297, 319.
structure of 229.
conveyance of 267.
Seminal leaves, 54.
Sensibility, 18.
Sensitive plant, 18.
Sepals, 195.
Shoot, 47.
Silex, 64, 83.
Siliques, 219.
Sleep of plants, 92.
Slip, 179, 182, 185.
Smoke, 285.
Smut, 295.
Solanum family, 345.
Social plants, 271.
Soda, 64, 83.
Soil, 147.
— argillaceous, 144.
— silicious, 144.
— improvement of 147, 152.
Soldering, 260.
S. rot, 158.
Storghum, 337.
Spade, 148.
Spanish chesnut, 224.
Species, 240, 263,272.
Spelt, 331.
Spermoderm, 210,226, 332.
Spike, 201.
Spindle-shaped root, 30.
Spongiole, 26, 27.
Stamens, 198, 204, 211, 243, 279.
Standards, 302.
Stapedra, 75.
Starch, 335.
Station of plants, 265.
Stem, 34.
subterraneous, 35.
endogenous, 36.
—— exogenous, 36.
—- structure of 37.
— germs of 181.
Steppes, 145.
Stigina, 198.
Stipula, 52.
Stock, 183.
Stoma, 51, 67.
Stones, 152.
Stone-fruit, 217.
§: 332. 222
trawbe º
sº
Subdivision of plants, 179.
Succulent leaves, 53.
*mºs plane 185, 186.
Sugar, 315. *
Sugar-cane, 39, 180.
Sulphate of lime, 155.
Sur eſcorse, 302.
Sycamore, 306.
Syngenesia, 208.
T.
Taillis, 302.
Tap-root, 30.
Tar, 87.
Temperature, 99, 105, 118
Tendrils, 50, 280.
Testa, 226.
Thorns, 50, 281.
Tillage, 144.
Timothy grass, 32.
Tomato, 345.
Topinambour, 329.
Torus, 200, 222.
Tracheae, 22. 207
Tragopogon, *
tºº, 307.
Trees, cultivation of 299.
latitude of 119, 319, 340.
seedling, 190.
— grafting of 188.
#. class, hard wood, 300.
–2d dino, softwood,30ſº
— 3d do., resinous wood, 301
for timber, 30l.
for fuel, 301.
transplanting, 307.
Trenches, 132, 150.
Triticum spelta, 331.
– turgidum, 335.
Tuberous roots, 32,322.
Tubular florets, 212.
Tuft, 209.
Tulip, 274.
Turnip, 329, 343.
Turpentine, 87.
35 4.
INDEX,
U.
Umbel, 200.
Umbelliferous family, 345.
V.
Vaccinium ..º. 268.
oxycoccus, 268.
Valerianae, §
Valves, 214.
Variations, 263,273.
Variegated leaves, 283.
Varieties, 263, 273.
Warnishes, 87.
Vascular system, 22.
Vegetable poison, 18.
Verticellate, 220.
Vine, 171, 177, 280, 316.
Wiscum album, or mistletoe, 26.
Vitex agnus castus, 100.
Wolatile oils, 86, 88.
W.
Walnut, 313, 340.
Water, 82, 114, 120, 174, 204, 336,
of lakes, 122.
of ponds, 122.
of rivers, 122.
of springs, 122.
of marshes, 122.
of rain, 123.
Watering, 109.
–
Watering, artificial modes of 130
— pots, or engines, 130.
y filtration, 130, 131.
by ºfº, 130, 132.
seeds, 125.
meadows, 125.
— corn, 125.
— fruit-trees, 125.
Weeds, 118, 167.
Wheat, 176,333.
Polish, 335.
White frost, 116.
White wood, 43.
Whorl, 196.
Willow grass, 34.
tree, 181.
Wind, 107,127.
—, sirocco, 107.
, mistral, 107.
—, bise, 107.
Wood, 23, 37, 40, 121, 173.
— combustion of 83.
—, frozen, 47.
Woody fibre, 44.
X.
Xylophylla, 279.
Y.
Yest, 334.
Yucca, 39.
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