Part 7 out of 7
open their mouths on the external surfaces of the bark and leaves, and
on the internal surfaces of all the cells, and between the bark and the
alburnum or sap-wood; the existence of these is shewn, because a leaf
plucked off and laid with its under side on water will not wither so
soon as if left in the dry air,--the same if the bark alone of a branch
which is separated from a tree be kept moist with water,--and lastly, by
moistening the alburnum or sap-wood alone of a branch detached from a
tree it will not so soon wither as if left in the dry air. By the
following experiment these vessels were agreeably visible by a common
magnifying glass, I placed in the summer of 1781 the footstalks of some
large fig-leaves about an inch deep in a decoction of madder, (rubia
tinctorum,) and others in a decoction of logwood, (haematoxylum
campechense,) along with some sprigs cut off from a plant of picris,
these plants were chosen because their blood is white, after some hours,
and on the next day, on taking out either of these and cutting off from
its bottom about a quarter of an inch of the stalk an internal circle of
red points appeared, which were the ends of absorbent vessels coloured
red with the decoction, while an external ring of arteries was seen to
bleed out hastily a milky juice, and at once evinced both the absorbent
and arterial system. These absorbent vessels have been called by Grew,
and Malphigi, and some other philosophers, bronchi, and erroneously
supposed to be air-vessels. It is probable that these vessels, when cut
through, may effuse their fluids, and receive air, their sides being too
stiff to collapse; since dry wood emits air-bubles in the exhausted
receiver in the same manner as moist wood.
The structure of these vegetable absorbents consists of a spiral line,
and not of a vessel interrupted with valves like the animal lymphatics,
since on breaking almost any tender leaf and drawing out some of the
fibres which adhere longest this spiral structure becomes visible even
to the naked eye, and distinctly so by the use of a common lens. See
Grew, Plate 51.
In such a structure it is easy to conceive how a vermicular or
peristaltic motion of the vessel beginning at the lowest part of it,
each spiral ring successively contracting itself till it fills up the
tube, must forcibly push forwards its contents, as from the roots of
vines in the bleeding season; and if this vermicular motion should begin
at the upper end of the vessel it is as easy to see how it must carry
its contained fluid in a contrary direction. The retrograde motion of
the vegetable absorbent vessels is shewn by cutting a forked branch from
a tree, and immersing a part of one of the forks in water, which will
for many days prevent the other from withering; or it is shewn by
planting a willow branch with the wrong end upwards. This structure in
some degree obtains in the esophagus or throat of cows, who by similar
means convey their food first downwards and afterward upwards by a
retrograde motion of the annular muscles or cartilages for the purpose
of a second mastication of it.
II. The fluids thus drank up by the vegetable absorbent vessels from the
earth, or from the atmosphere, or from their own cells and interfaces,
are carried to the foot-stalk of every leaf, where the absorbents
belonging to each leaf unite into branches, forming so many pulmonary
arteries, and are thence dispersed to the extremities of the leaf, as
may be seen in cutting away slice after slice the footstalk of a horse-
chesnut in September before the leaf falls. There is then a compleat
circulation in the leaf; a pulmonary vein receiving the blood from the
extremities of each artery on the upper side of the leaf, and joining
again in the footstalk of the leaf these veins produce so many arteries,
or aortas, which disperse the new blood over the new bark, elongating
its vessels, or producing its secretions; but as a reservoir of blood
could not be wanted by a vegetable bud which takes in its nutriment at
all times, I imagine there is no venous system, no veins properly so
called, which receive the blood which was to spare, and return it into
the pulmonary or arterial system.
The want of a system of veins was countenanced by the following
experiment; I cut off several stems of tall spurge, (Euphorbia
helioscopia) in autumn, about the centre of the plant, and observed
tenfold the quantity of milky juice ooze from the upper than from the
lower extremity, which could hardly have happened if there had been a
venous system of vessels to return the blood from the roots to the
Thus the vegetable circulation, complete in the lungs, but probably in
the other part of the system deficient in respect to a system of
returning veins, is carried forwards without a heart, like the
circulation through the livers of animals where the blood brought from
the intestines and mesentery by one vein is dispersed through the liver
by the vena portarum, which assumes the office of an artery. See Note
At the same time so minute are the vessels in the intertexture of the
barks of plants, which belong to each individual bud, that a general
circulation may possibly exist, though we have not yet been able to
discover the venous part of it.
There is however another part of the circulation of vegetable juices
visible to the naked eye, and that is in the corol or petals of flowers,
in which a part of the blood of the plant is exposed to the influence of
the air and light in the same manner as in the foliage, as will be
mentioned more at large in Notes XXXVII and XXXIX.
These circulations of their respective fluids seem to be carried on in
the vessels of plants precisely as in animal bodies by their
irritability to the stimulus of their adapted fluids, and not by any
mechanical or chemical attraction, for their absorbent vessels propel
the juice upwards, which they drink up from the earth, with great
violence; I suppose with much greater than is exerted by the lacteals of
animals, probably owing to the greater minuteness of these vessels in
vegetables and the greater rigidity of their coats. Dr. Hales in the
spring season cut off a vine near the ground, and by fixing tubes on the
remaining stump of it, found the sap to rise twenty-one feet in the tube
by the propulsive power of these absorbents of the roots of it. Veget.
Stat. p. 102. Such a power can not be produced by capillary attraction,
as that could only raise a fluid nearly to the upper edge of the
attracting cylinder, but not enable it to flow over that edge, and much
less to rise 21 feet above it. What then can this power be owing to?
Doubtless to the living activity of the absorbent vessels, and to their
increased vivacity from the influence of the warmth of the spring
succeeding the winter's cold, and their thence greater susceptibility to
irritation from the juices which they absorb, resembling in all
circumstances the action of the living vessels of animals.
NOTE XXXVII--VEGETABLE RESPIRATION.
_While spread in air the leaves respiring play._
CANTO IV. l. 421.
I. There have been various opinions concerning the use of the leaves of
plants in the vegetable oeconomy. Some have contended that they are
perspiratory organs; this does not seem probable from an experiment of
Dr. Hales, Veg. Stat. p. 30. He found by cutting off branches of trees
with apples on them, and taking off the leaves, that an apple exhaled
about as much as two leaves, the surfaces of which were nearly equal to
the apple; whence it would appear that apples have as good a claim to be
termed perspiratory organs as leaves. Others have believed them
excretory organs of excrementious juices; but as the vapour exhaled from
vegetables has no taste, this idea is no more probable than the other;
add to this that in moist weather, they do not appear to perspire or
exhale at all.
The internal surface of the lungs or air-vessels in men, are said to be
equal to the external surface of the whole body, or about fifteen square
feet; on this surface the blood is exposed to the influence of the
respired air through the medium however of a thin pellicle; by this
exposure to the air it has its colour changed from deep red to bright
scarlet, and acquires something so necessary to the existence of life,
that we can live scarcely a minute without this wonderful process.
The analogy between the leaves of plants and the lungs or gills of
animals seems to embrace so many circumstances, that we can scarcely
withhold our assent to their performing similar offices.
I. The great surface of the leaves compared to that of the trunk and
branches of trees is such, that it would seem to be an organ well
adapted for the purpose of exposing the vegetable juices to the
influence of the air; this however we shall see afterwards is probably
performed only by their upper surfaces, yet even in this case the
surface of the leaves in general bear a greater proportion to the
surface of the tree, than the lungs of animals to their external
2. In the lungs of animal, the blood after having been exposed to the
air in the extremities of pulmonary artery, is changed in colour from
deep red to bright scarlet, and certainly in some of its essential
properties; it is then collected by the pulmonary vein and returned to
the heart. To shew a similarity of circumstance in the leaves of plants
the following experiment was made, June 24, 1781: A stalk with leaves
and seed-vessels of large spurge (Euphorbia helioscopia) had been
several days placed in a decoction of madder (Rubia tinctorum) so that
the lower part of the stem, and two of the undermost leaves were
immersed in it. After having washed the immersed leaves in clear water,
I could readily discern the colour of the madder passing along the
middle rib of each leaf. This red artery was beautifully visible both on
the under and upper surface of the leaf; but on the upper side many red
branches were seen going from it to the extremities of the leaf, which
on the other side were not visible except by looking through it against
the light. On this under side a system of branching vessels carrying a
pale milky fluid were seen coming from the extremities of the leaf, and
covering the whole underside of it, and joining into two large veins,
one on each side of the red artery in the middle rib of the leaf, and
along with it descending to the footstalk or petiole. On slitting one of
these leaves with scissars, and having a common magnifying lens ready,
the milky blood was seen oozing out of the returning veins on each side
of the red artery in the middle rib, but none of the red fluid from the
All these appearances were more easily seen in a leaf of Picris treated
in the same manner; for in this milky plant the stems and middle rib of
the leaves are sometimes naturally coloured reddish, and hence the
colour of the madder seemed to pass further into the ramifications of
their leaf-arteries, and was there beautifully visible with the
returning branches of milky veins on each side.
3. From these experiments the upper surface of the leaf appeared to be
the immediate organ of respiration, because the coloured fluid was
carried to the extremities of the leaf by vessels most conspicuous on
the upper surface, and there changed into a milky fluid, which is the
blood of the plant, and then returned by concomitant veins on the under
surface, which were seen to ooze when divided with scissars, and which
in Picris, particularly render the under surface of the leaves greatly
whiter than the upper one.
4. As the upper surface of leaves constitutes the organ of respiration,
on which the sap is exposed in the terminations of arteries beneath a
thin pellicle to the action of the atmosphere, these surfaces in many
plants strongly repel moisture, as cabbage-leaves, whence the particles
of rain lying over their surfaces without touching them, as observed by
Mr. Melville (Essays Literary and Philosop. Edinburgh) have the
appearance of globules of quicksilver. And hence leaves laid with the
upper surfaces on water, wither as soon as in the dry air, but continue
green many days, if placed with the under surfaces on water, as appears
in the experiments of Mons. Bonnet (Usage des Fevilles.) Hence some
aquatic plants, as the Water-lily (Nymphoea) have the lower sides of
their leaves floating on the water, while the upper surfaces remain dry
in the air.
5. As those insects, which have many spiracula, or breathing apertures,
as wasps and flies, are immediately suffocated by pouring oil upon
them, I carefully covered with oil the surfaces of several leaves of
Phlomis, of Portugal Laurel, and Balsams, and though it would not
regularly adhere, I found them all die in a day or two.
Of aquatic leaves, see Note on Trapa and on Fucus, in Vol. II. to which
must be added that many leaves are furnished with muscles about their
footstalks, to turn their upper surfaces to the air or light, as Mimosa
and Hedysarum gyrans. From all these analogies I think there can be no
doubt but that leaves of trees are their lungs, giving out a phlogistic
material to the atmosphere, and absorbing oxygene or vital air.
6. The great use of light to vegetation would appear from this theory to
be by disengaging vital air from the water which they perspire, and
thence to facilitate its union with their blood exposed beneath the thin
surface of their leaves; since when pure air is thus applied, it is
probable, that it can be more readily absorbed. Hence in the curious
experiments of Dr. Priestley and Mr. Ingenhouze, some plants purified
air less than others, that is, they perspired less in the sunshine; and
Mr. Scheele found that by putting peas into water, which about half-
covered them, that they converted the vital air into fixed air, or
carbonic acid gas, in the same manner as in animal respiration. See Note
7. The circulation in the lungs or leaves of plants is very similar to
that of fish. In fish the blood after having passed through their gills
does not return to the heart as from the lungs of air-breathing animals,
but the pulmonary vein taking the structure of an artery after having
received the blood from the gills, which there gains a more florrid
colour, distributes it to the other parts of their bodies. The same
structure occurs in the livers of fish, whence we see in those animals
two circulations independent of the power of the heart, viz. that
beginning at the termination of the veins of the gills, and branching
through the muscles; and that which passes through the liver; both which
are carried on by the action of those respective arteries and veins.
Monro's Physiology of Fish, p. 19.
The course of the fluids in the roots, leaves, and buds of vegetables
seems to be performed in a manner similar to both these. First the
absorbent vessels of the roots and surfaces unite at the footstalk of
the leaf; and then, like the Vena Portarum, an artery commences without
the intervention of a heart, and spreads the sap in its numerous
ramifications on the upper surface of the leaf; here it changes its
colour and properties, and becomes vegetable blood; and is again
collected by a pulmonary vein on the under surface of the leaf. This
vein, like that which receives the blood from the gills of fish, assumes
the office and name of an artery, and branching again disperses the
blood upward to the bud from the footstalk of the leaf, and downward to
the roots; where it is all expended in the various secretions, the
nourishment and growth of the plant, as fast as it is prepared.
II. The organ of respiration already spoken of belongs particularly to
the shoots or buds, but there is another pulmonary system, perhaps
totally independent of the green foliage, which belongs to the
fructification only, I mean the corol or petals. In this there is an
artery belonging to each petal, which conveys the vegetable blood to its
extremities, exposing it to the light and air under a delicate membrane
covering the internal surface of the petal, where it often changes its
colour, as is beautifully seen in some party-coloured poppies; though it
is probable some of the iridescent colours of flowers may be owing to
the different degrees of tenuity of the exterior membrane of the leaf
refracting the light like soap-bubbles, the vegetable blood is then
returned by correspondent vegetable veins, exactly as in the green
foliage; for the purposes of the important secretions of honey, wax, the
finer essential oil, and the prolific dust of the anthers.
1. The vascular structure of the corol as above described, and which is
visible to the naked eye, and its exposing the vegetable juices to the
air and light during the day, evinces that it is a pulmonary organ.
2. As the glands which produce the prolific dust of the anthers, the
honey, wax, and frequently some odoriferous essential oil, are generally
attached to the corol, and always fall off and perish with it, it is
evident that the blood is elaborated or oxygenated in this pulmonary
system for the purpose of these important secretions.
3. Many flowers, as the Colchicum, and Hamamelis arise naked in autumn,
no green leaves appearing till the ensuing spring; and many others put
forth their flowers and complete their impregnation early in the spring
before the green foliage appears, as Mezereon, cherries, pears, which
shews that these corols are the lungs belonging to the fructification.
4. This organ does not seem to have been necessary for the defence of
the stamens and pistils, since the calyx of many flowers, as Tragopogon,
performs this office; and in many flowers these petals themselves are so
tender as to require being shut up in the calyx during the night, for
what other use then can such an apparatus of vessels be designed?
5. In the Helleborus-niger, Christmas-rose, after the seeds are grown to
a certain size, the nectaries and stamens drop off, and the beautiful
large white petals change their colour to a deep green, and gradually
thus become a calyx inclosing and defending the ripening seeds, hence it
would seem that the white vessels of the corol served the office of
exposing the blood to the action of the air, for the purposes of
separating or producing the honey, wax, and prolific dust, and when
these were no longer wanted, that these vessels coalesced like the
placental vessels of animals after their birth, and thus ceased to
perform that office and lost at the same time their white colour. Why
should they loose their white colour, unless they at the same time lost
some other property besides that of defending the seed-vessel, which
they still continue to defend?
6. From these observations I am led to doubt whether green leaves be
absolutely necessary to the progress of the fruit-bud after the last
year's leaves are fallen off. The green leaves serve as lungs to the
shoots and foster the new buds in their bosoms, whether these buds be
leaf-buds or fruit-buds; but in the early spring the fruit-buds expand
their corols, which are their lungs, and seem no longer to require green
leaves; hence the vine bears fruit at one joint without leaves, and puts
out a leaf-bud at another joint without fruit. And I suppose the green
leaves which rise out of the earth in the spring from the Colchicum are
for the purpose of producing the new bulb, and its placenta, and not for
the giving maturity to the seed. When currant or goosberry trees lose
their leaves by the depredation of insects the fruit continues to be
formed, though less sweet and less in size.
7. From these facts it appears that the flower-bud after the corol falls
off, (which is its lungs,) and the stamens and nectary along with it,
becomes simply an uterus for the purpose of supplying the growing
embryon with nourishment, together with a system of absorbent vessels
which bring the juices of the earth to the footstalk of the fruit, and
which there changes into an artery for the purpose of distributing the
sap for the secretion of the saccharine or farinaceous or acescent
materials for the use of the embryon. At the same time as all the
vessels of the different buds of trees inosculate or communicate with
each other, the fruit becomes sweeter and larger when the green leaves
continue on the tree, but the mature flowers themselves, (the succeeding
fruit not considered) perhaps suffer little injury from the green leaves
being taken off, as some florists have observed.
8. That the vessels of different vegetable buds inosculate in various
parts of their circulation is rendered probable by the increased growth
of one bud, when others in its vicinity are cut away; as it thus seems
to receive the nourishment which was before divided amongst many.
NOTE XXXVIII.--VEGETABLE IMPREGNATION.
_Love out their hour and leave their lives in air._
CANTO IV. l. 456.
From the accurate experiments and observations of Spallanzani it appears
that in the Spartium Junceum, rush-broom, the very minute seeds were
discerned in the pod at least twenty days before the flower is in full
bloom, that is twenty days before fecundation. At this time also the
powder of the anthers was visible, but glued fast to their summits. The
seeds however at this time, and for ten days after the blossom had
fallen off, appeared to consist of a gelatinous substance. On the
eleventh day after the falling of the blossom the seeds became heart-
shape, with the basis attached by an appendage to the pod, and a white
point at the apex; this white point was on pressure found to be a cavity
including a drop of liquor.
On the 25th day the cavity which at first appeared at the apex was much
enlarged and still full of liquor, it also contained a very small semi-
transparent body, of a yellowish colour, gelatinous, and fixed by its
two opposite ends to the sides of the cavity.
In a month the seed was much enlarged and its shape changed from a heart
to a kidney, the little body contained in the cavity was increased in
bulk and was less transparent, and gelatinous, but there yet appeared no
On the 40th day the cavity now grown larger was quite filled with the
body, which was covered with a thin membrane; after this membrane was
removed the body appeared of a bright green, and was easily divided by
the point of a needle into two portions, which manifestly formed the two
lobes, and within these attached to the lower part the exceedingly small
plantule was easily perceived.
The foregoing observations evince, 1. That the seeds exist in the
ovarium many days before fecundation. 2. That they remain for some time
solid, and then a cavity containing a liquid is formed in them. 3. That
after fecundation a body begins to appear within the cavity fixed by two
points to the sides, which in process of time proves to be two lobes
containing a plantule. 4. That the ripe seed consists of two lobes
adhering to a plantule, and surrounded by a thin membrane which is
itself covered with a husk or cuticle. Spalanzani's Dissertations, Vol.
II. p. 253.
The analogy between seeds and eggs has long been observed, and is
confirmed by the mode of their production. The egg is known to be formed
within the hen long before its impregnation; C.F. Wolf asserts that the
yolk of the egg is nourished by the vessels of the mother, and that it
has from those its arterial and venous branches, but that after
impregnation these vessels gradually become impervious and obliterated,
and that new ones are produced from the fetus and dispersed into the
yolk. Haller's Physiolog. Tom. VIII. p. 94. The young seed after
fecundation, I suppose, is nourished in a similar manner from the
gelatinous liquor, which is previously deposited for that purpose; the
uterus of the plant producing or secreting it into a reservoir or amnios
in which the embryon is lodged, and that the young embryon is furnished
with vessels to absorb a part of it, as in the very early embryon in the
The spawn of frogs and of fish is delivered from the female before its
impregnation. M. Bonnet says that the male salamander darts his semen
into the water, where it forms a little whitish cloud which is
afterwards received by the swoln anus of the female, and she is
fecundated.--He adds that marine plants approach near to these animals,
as the male does not project a fine powder but a liquor which in like
manner forms a little cloud in the water.--And further adds, who knows
but the powder of the stamina of certain plants may not make some
impression on certain germs belonging to the animal kingdom! Letter
XLIII. to Spalanzani, Oevres Philos.
Spalanzani found that the seminal fluid of frogs and dogs even when
diluted with much water retained its prolific quality. Whether this
quality be simply a stimulus exciting the egg into animal action, which
may be called a vivifying principle, or whether part of it be actually
conjoined with the egg is not yet determined, though the latter seems
more probable from the frequent resemblance of the fetus to the male
parent. A conjunction however of both the male and female influence
seems necessary for the purpose of reproduction throughout all organized
nature, as well in hermaphrodite insects, microscopic animals, and
polypi, and exists as well in the formation of the buds of vegetables as
in the production of their seeds, which is ingeniously conceived and
explained by Linneus. After having compared the flower to the larva of a
butterfly, confining of petals instead of wings, calyxes instead of
wing-sheaths, with the organs of reproduction, and having shewn the use
of the farina in fecundating the egg or seed, he proceeds to explain the
production of the bud. The calyx of a flower, he says, is an expansion
of the outer bark, the petals proceed from the inner bark or rind, the
stamens from the alburnum or woody circle, and the style from the pith.
In the production and impregnation of the seed a commixture of the
secretions of the stamens and style are necessary; and for the
production of a bud he thinks the medulla or pith bursts its integuments
and mixes with the woody part or alburnum, and these forcing their
passage through the rind and bark constitute the bud or viviparous
progeny of the vegetable. System of Vegetables translated from Linneus,
It has been supposed that the embryon vegetable after fecundation, by
its living activity or stimulus exerted on the vessels of the parent
plant, may produce the fruit or seed-lobes, as the animal fetus produces
its placenta, and as vegetable buds may be supposed to produce their
umbilical vessels or roots down the bark of the tree. This in respect to
the production of the fruit surrounding the seeds of trees has been
assimilated to the gall-nuts on oak-leaves, and to the bedeguar on
briars, but there is a powerful objection to this doctrine, viz. that
the fruit of figs, all which are female in this country, grow nearly as
large without fecundation, and therefore the embryon has in them no
NOTE XXXIX.--VEGETABLE GLANDULATION.
_Seeks, where fine pores their dulcet balm distil._
CANTO IV. l. 503.
The glands of vegetables which separate from their blood the mucilage,
starch, or sugar for the placentation or support of their seeds, bulbs,
and buds; or those which deposit their bitter, acrid, or narcotic juices
for their defence from depredations of insects or larger animals; or
those which secrete resins or wax for their protection from moisture or
frosts, consist of vessels too fine for the injection or absorption of
coloured fluids, and have not therefore yet been exhibited to the
inspection even of our glasses, and can therefore only be known by their
effects, but one of the most curious and important of all vegetable
secretions, that of honey, is apparent to our naked eyes, though before
the discoveries of Linneus the nectary or honey-gland had not even
acquired a name.
The odoriferous essential oils of several flowers seem to have been
designed for their defence against the depredations of insects, while
their beautiful colours were a necessary consequence of the size of the
particles of their blood, or of the tenuity of the exterior membrane of
the petal. The use of the prolific dust is now well ascertained, the wax
which covers the anthers prevents this dust from receiving moisture,
which would make it burst prematurely and thence prevent its application
to the stigma, as sometimes happens in moist years and is the cause of
deficient fecundation both of our fields and orchards.
The universality of the production of honey in the vegetable world, and
the very complicated apparatus which nature has constructed in many
flowers, as well as the acrid or deleterious juices she has furnished
those flowers with (as in the Aconite) to protect this honey from rain
and from the depredations of insects, seem to imply that this fluid is
of very great importance in the vegetable economy; and also that it was
necessary to expose it to the open air previous to its reabsorption into
the vegetable vessels.
In the animal system the lachrymal gland separates its fluid into the
open air for the purpose of moistening the eye, of this fluid the part
which does not exhale it absorbed by the puncta lachrymalia and carried
into the nostrils; but as this is not a nutritive fluid the analogy goes
no further than its secretion into the open air and its reabsorption
into the system; every other secreted fluid in the animal body is in
part absorbed again into the system, even those which are esteemed
excrementitious, as the urine and perspirable matter, of which the
latter is secreted, like the honey, into the external air. That the
honey is a nutritious fluid, perhaps the most so of any vegetable
production, appears from its great similarity to sugar, and from its
affording sustenance to such numbers of insects, which live upon it
solely during summer, and lay it up for their winter provision. These
proofs of its nutritive nature evince the necessity of its reabsorption
into the vegetable system for some useful purpose.
This purpose however has as yet escaped the researches of philosophical
botanists. M. Pontedera believes it designed to lubricate the vegetable
uterus, and compares the horn-like nectaries of some flowers to the
appendicle of the caecum intestinum of animals. (Antholog. p. 49.)
Others have supposed that the honey, when reabsorbed, might serve the
purpose of the liquor amnii, or white of the egg, as a nutriment for the
young embryon or fecundated seed in its early state of existence. But as
the nectary is found equally general in male flowers as in female ones;
and as the young embryon or seed grows before the petals and nectary are
expanded, and after they fall off; and, thirdly, as the nectary so soon
falls off after the fecundation of the pistillum; these seem to be
insurmountable objections to both the above-mentioned opinions.
In this state of uncertainty conjectures may be of use so far as they
lead to further experiment and investigation. In many tribes of insects,
as the silk-worm, and perhaps in all the moths and butterflies, the male
and female parents die as soon as the eggs are impregnated and excluded;
the eggs remaining to be perfected and hatched at some future time. The
same thing happens in regard to the male and female parts of flowers;
the anthers and filaments, which constitute the male parts of the
flower, and the stigma and style, which constitute the female part of
the flower, fall off and die as soon as the seeds are impregnated, and
along with these the petals and nectary. Now the moths and butterflies
above-mentioned, as soon as they acquire the passion and the apparatus
for the reproduction of their species, loose the power of feeding upon
leaves as they did before, and become nourished by what?--by honey alone.
Hence we acquire a strong analogy for the use of the nectary or
secretion of honey in the vegetable economy, which is, that the male
parts of flowers, and the female parts, as soon as they leave their
fetus-state, expanding their petals, (which constitute their lungs,)
become sensible to the passion, and gain the apparatus for the
reproduction of their species, and are fed and nourished with honey like
the insects above described; and that hence the nectary begins its
office of producing honey, and dies or ceases to produce honey at the
same time with the birth and death of the stamens and the pistils;
which, whether existing in the same or in different flowers, are
separate and distinct animated beings.
Previous to this time the anthers with their filaments, and the stigmas
with their styles, are in their fetus-state sustained by their placental
vessels, like the unexpanded leaf-bud; with the seeds existing in the
vegetable womb yet unimpregnated, and the dust yet unripe in the cells
of the anthers. After this period they expand their petals, which have
been shewn above to constitute the lungs of the flower; the placental
vessels, which before nourished the anthers and the stigmas, coalesce or
cease to nourish them; and they now acquire blood more oxygenated by the
air, obtain the passion and power of reproduction, are sensible to heat,
and cold, and moisture, and to mechanic stimulus, and become in reality
insects fed with honey, similar in every respect except their being
attached to the tree on which they were produced.
Some experiments I have made this summer by cutting out the nectaries of
several flowers of the aconites before the petals were open, or had
become much coloured, some of these flowers near the summit of the
plants produced no seeds, others lower down produced seeds; but they
were not sufficiently guarded from the farina of the flowers in their
vicinity; nor have I had opportunity to try if these seeds would
I am acquainted with a philosopher, who contemplating this subject
thinks it not impossible, that the first insects were the anthers or
stigmas of flowers; which had by some means loosed themselves from their
parent plant, like the male flowers of Vallisneria; and that many other
insects have gradually in long process of time been formed from these;
some acquiring wings, others fins, and others claws, from their
ceaseless efforts to procure their food, or to secure themselves from
injury. He contends, that none of these changes are more
incomprehensible than the transformation of tadpoles into frogs, and
caterpillars into butterflies.
There are parts of animal bodies, which do not require oxygenated blood
for the purpose of their secretions, as the liver; which for the
production of bile takes its blood from the mesenteric veins, after it
must have lost the whole or a great part of its oxygenation, which it
had acquired in its passage through the lungs. In like manner the
pericarpium, or womb of the flower, continues to secrete its proper
juices for the present nourishment of the newly animated embryon-seed;
and the saccharine, acescent, or starchy matter of the fruit or seed-
lobes for its future growth; in the same manner as these things went on
before fecundation; that is, without any circulation of juices in the
petals, or production of honey in the nectary; these having perished and
fallen off with the male and female apparatus for impregnation.
It is probable that the depredations of insects on this nutritious fluid
must be injurious to the products of vegetation, and would be much more
so, but that the plants have either acquired means to defend their honey
in part, or have learned to make more than is absolutely necessary for
their own economy. In the same manner the honey-dew on trees is very
injurious to them; in which disease the nutritive fluid, the vegetable-
sap-juice, seems to be exsuded by a retrograde motion of the cutaneous
lymphatics, as in the sweating sickness of the last century. To prevent
the depredation of insects on honey a wealthy man in Italy is said to
have poisoned his neighbour's bees perhaps by mixing arsnic with honey,
against which there is a most flowery declamation in Quintilian. No.
XIII. As the use of the wax is to preserve the dust of the anthers from
moisture, which would prematurely burst them, the bees which collect
this for the construction of the combs or cells, must on this account
also injure the vegetation of a country where they too much abound.
It is not easy to conjecture why it was necessary that this secretion of
honey should be exposed to the open air in the nectary or honey-cup, for
which purpose so great an apparatus for its defence from insects and
from showers became necessary. This difficulty increases when we
recollect that the sugar in the joints of grass, in the sugar-cane, and
in the roots of beets, and in ripe fruits is produced without the
exposure to the air. On supposition of its serving for nutriment to the
anthers and stigmas it may thus acquire greater oxygenation for the
purpose of producing greater powers of sensibility, according to a
doctrine lately advanced by a French philosopher, who has endeavoured to
shew that the oxygene, or base of vital air, is the constituent
principle of our power of sensibility.
From this provision of honey for the male and female parts of flowers,
and from the provision of sugar, starch, oil, and mucilage, in the
fruits, seed-cotyledons, roots, and buds of plants laid up for the
nutriment of the expanding fetus, not only a very numerous class of
insects, but a great part of the larger animals procure their food; and
thus enjoy life and pleasure without producing pain to others, for these
seeds or eggs with the nutriment laid up in them are not yet endued with
The secretions from various vegetable glands hardened in the air produce
gums, resins, and various kinds of saccharine, saponaceous, and wax-like
substances, as the gum of cherry or plumb-trees, gum tragacanth from the
astragalus tragacantha, camphor from the laurus camphora, elemi from
amyris elemifera, aneme from hymenoea courbaril, turpentine from
pistacia terebinthus, balsam of Mecca from the buds of amyris
opobalsamum, branches of which are placed in the temples of the East on
account of their fragrance, the wood is called xylobalsamum, and the
fruit carpobalsamum; aloe from a plant of the same name; myrrh from a
plant not yet described; the remarkably elastic resin is brought into
Europe principally in the form of flasks, which look like black leather,
and are wonderfully elastic, and not penetrable by water, rectified
ether dissolves it; its flexibility is encreased by warmth and destroyed
by cold; the tree which yields this juice is the jatropha elastica, it
grows in Guaiana and the neighbouring tracts of America; its juice is
said to resemble wax in becoming soft by heat, but that it acquires no
elasticity till that property is communicated to it by a secret art,
after which it is poured into moulds and well dried and can no longer be
rendered fluid by heat. Mr. de la Borde physician at Cayenne has given
this account. Manna is obtained at Naples from the fraxinus ornus, or
manna-ash, it partly issues spontaneously, which is preferred, and
partly exsudes from wounds made purposely in the month of August, many
other plants yield manna more sparingly; sugar is properly made from the
saccharum officinale, or sugar-cane, but is found in the roots of beet
and many other plants; American wax is obtained from the myrica
cerifera, candle-berry myrtle, the berries are boiled in water and a
green wax separates, with luke-warm water the wax is yellow: the seed of
croton sebiferum are lodged in tallow; there are many other vegetable
exsudations used in the various arts of dyeing, varnishing, tanning,
lacquering, and which supply the shop of the druggist with medicines and
There is another analogy, which would seem to associate plants with
animals, and which perhaps belongs to this Note on Glandulation, I mean
the similarity of their digestive powers. In the roots of growing
vegetables, as in the process of making malt, the farinaceous part of
the seed is converted into sugar by the vegetable power of digestion in
the same manner as the farinaceous matter of seeds are converted into
sweet chyle by the animal digestion. The sap-juice which rises in the
vernal months from the roots of trees through the alburnum or sap-wood,
owes its sweetness I suppose to a similar digestive power of the
absorbent system of the young buds. This exists in many vegetables in
great abundance as in vines, sycamore, birch, and most abundantly in the
palm-tree, (Isert's Voyage to Guinea,) and seems to be a similar fluid
in all plants, as chyle is similar in all animals.
Hence as the digested food of vegetables consists principally of sugar,
and from that is produced again their mucilage, starch, and oil, and
since animals are sustained by these vegetable productions, it would
seem that the sugar-making process carried on in vegetable vessels was
the great source of life to all organized beings. And that if our
improved chemistry should ever discover the art of making sugar from
fossile or aerial matter without the assistance of vegetation, food for
animals would then become as plentiful as water, and mankind might live
upon the earth as thick as blades of grass, with no restraint to their
numbers but the want of local room.
It would seem that roots fixed in the earth, and leaves innumerable
waving in the air were necessary for the decomposition of water, and the
conversion of it into saccharine matter, which would have been not only
cumberous but totally incompatible with the locomotion of animal bodies.
For how could a man or quadruped have carried on his head or back a
forest of leaves, or have had long branching lacteal or absorbent
vessels terminating in the earth? Animals therefore subsist on
vegetables; that is, they take the matter so far prepared, and have
organs to prepare it further for the purposes of higher animation, and
greater sensibility. In the same manner the apparatus of green leaves
and long roots were found inconvenient for the more animated and
sensitive parts of vegetable-flowers, I mean the anthers and stigmas,
which are therefore separate beings, endued with the passion and power
of reproduction, with lungs of their own, and fed with honey, a food
ready prepared by the long roots and green leaves of the plant, and
presented to their absorbent mouths.
From this outline a philosopher may catch a glimpse of the general
economy of nature; and like the mariner cast upon an unknown shore, who
rejoiced when he saw the print of a human foot upon the sand, he may cry
out with rapture, "A GOD DWELLS HERE."
NOTE I ... METEORS.
There are four strata of the atmosphere, and four kinds of meteors. 1.
Lightning is electric, exists in visible clouds, its short course, and
red light. 2. Shooting stars exist in invisible vapour, without sound,
white light, have no luminous trains. 3. Twilight; fire-balls move
thirty miles in a second, and are about sixty miles high, have luminous
trains, occasioned by an electric spark passing between the aerial and
inflammable strata of the atmosphere, and mixing them and setting them
on fire in its passage; attracted by volcanic eruptions; one thousand
miles through such a medium resists less than the tenth of an inch of
glass. 4. Northern lights not attracted to a point but diffused; their
colours; passage of electric fire in vacuo dubious; Dr. Franklin's
theory of northern lights countenanced in part by the supposition of
a superior atmosphere of inflammable air; antiquity of their appearance;
described in Maccabees.
NOTE II ... PRIMARY COLOURS.
The rainbow was in part understood before Sir Isaac Newton; the seven
colours were discovered by him; Mr. Gallon's experiments on colours;
manganese and lead produce colourless glass.
NOTE III ... COLOURED CLOUDS.
The rays refracted by the convexity of the atmosphere; the particles of
air and of water are blue; shadow by means of a candle in the day; halo
round the moon in a fog; bright spot in the cornea of the eye; light
from cat's eyes in the dark, from a horse's eyes in a cavern, coloured
by the choroid coat within the eye.
NOTE IV ... COMETS.
Tails of comets from rarified vapour, like northern lights, from
electricity; twenty millions of miles long; expected comet.
NOTE V ... SUN'S RAYS.
Dispute about phlogiston; the sun the fountain from whence all
phlogiston is derived; its rays not luminous till they arrive at our
atmosphere; light owing to their combustion with air, whence an unknown
acid; the sun is on fire only on its surface; the dark spots on it are
excavations through its luminous crust.
NOTE VI ... CENTRAL FIRES.
Sun's heat much less than that from the fire at the earth's centre;
sun's heat penetrates but a few feet in summer; some mines are warm;
warm springs owing to subterraneous fire; situations of volcanos on high
mountains; original nucleus of the earth; deep vallies of the ocean;
distant perception of earthquakes; great attraction of mountains;
variation of the compass; countenance the existence of a cavity or fluid
lava within the earth.
NOTE VII ... ELEMENTARY HEAT.
Combined and sensible heat; chemical combinations attract heat,
solutions reject heat; ice cools boiling water six times as much as cold
water cools it; cold produced by evaporation; heat by devaporation;
capacities of bodies in respect to heat, 1. Existence of the matter of
heat shewn from the mechanical condensation and rarefaction of air, from
the steam produced in exhausting a receiver, snow from rarefied air,
cold from discharging an air-gun, heat from vibration or friction; 2.
Matter of heat analogous to the electric fluid in many circumstances,
explains many chemical phenomena.
NOTE VIII ... MEMNON'S LYRE.
Mechanical impulse of light dubious; a glass tube laid horizontally
before a fire revolves; pulse-glass suspended on a centre; black leather
contracts in the sunshine; Memnon's statue broken by Cambyses.
NOTE IX ... LUMINOUS INSECTS.
Eighteen species of glow-worm, their light owing to their respiration in
transparent lungs; Acudia of Surinam gives light enough to read and draw
by, use of its light to the insect; luminous sea-insects adhere to the
skin of those who bathe in the ports of Languedoc, the light may arise
from putrescent slime.
NOTE X ... PHOSPHORUS.
Discovered by Kunkel, Brandt, and Boyle; produced in respiration, and by
luminous insects, decayed wood, and calcined shells; bleaching a slow
combustion in which the water is decomposed; rancidity of animal fat
owing to the decomposition of water on its surface; aerated marine acid
does not whiten or bleach the hand.
NOTE XI ... STEAM-ENGINE.
Hero of Alexandria first applied steam to machinery, next a French
writer in 1630, the Marquis of Worcester in 1655, Capt. Savery in 1689,
Newcomen and Cawley added the piston; the improvements of Watt and
Boulton; power of one of their large engines equal to two hundred
NOTE XII ... FROST.
Expansion of water in freezing; injury done by vernal frosts; fish,
eggs, seeds, resist congelation; animals do not resist the increase of
heat; frosts do not meliorate the ground, nor are in general salubrious;
damp air produces cold on the skin by evaporation; snow less pernicious
to agriculture than heavy rains for two reasons.
NOTE XIII ... ELECTRICITY.
1. _Points_ preferable to knobs for defence of buildings; why points
emit the electric fluid; diffusion of oil on water; mountains are points
on the earth's globe; do they produce ascending currents of air? 2.
_Fairy-rings_ explained; advantage of paring and burning ground.
NOTE XIV ... BUDS AND BULBS.
A tree is a swarm of individual plants; vegetables are either oviparous
or viviparous; are all annual productions like many kinds of insects?
Hybernacula, a new bark annually produced over the old one in trees and
in some herbaceous plants, whence their roots seem end-bitten; all
bulbous roots perish annually; experiment on a tulip-root; both the
leaf-bulbs and the flower-bulbs are annually renewed.
NOTE XV ... SOLAR VOLCANOS.
The spots in the sun are cavities, some of them four thousand miles deep
and many times as broad; internal parts of the sun are not in a state of
combustion; volcanos visible in the sun; all the planets together are
less than one six hundred and fiftieth part of the sun; planets were
ejected from the sun by volcanos; many reasons shewing the probability
of this hypothesis; Mr. Buffon's hypothesis that planets were struck off
from the sun by comets; why no new planets are ejected from the sun;
some comets and the georgium sidus may be of later date; Sun's matter
decreased; Mr. Ludlam's opinion, that it is possible the moon might be
projected from the earth.
NOTE XVI ... CALCAREOUS EARTH.
High mountains and deep mines replete with shells; the earth's nucleus
covered with limestone; animals convert water into limestone; all the
calcareous earth in the world formed in animal and vegetable bodies;
solid parts of the earth increase; the water decreases; tops of
calcareous mountains dissolved; whence spar, marbles, chalk,
stalactites; whence alabaster, fluor, flint, granulated limestone, from
solution of their angles, and by attrition; tupha deposited on moss;
limestones from shells with animals in them; liver-stone from fresh-
water muscles; calcareous earth from land-animals and vegetables, as
marl; beds of marble softened by fire; whence Bath-stone contains lime
as well as limestone.
NOTE XVII ... MORASSES.
The production of morasses from fallen woods; account by the Earl
Cromartie of a new morass; morasses lose their salts by solution in
water; then their iron; their vegetable acid is converted into marine,
nitrous, and vitriolic acids; whence gypsum, alum, sulphur; into fluor-
acid, whence fluor; into siliceous acid, whence flint, the sand of the
sea, and other strata of siliceous sand and marl; some morasses ferment
like new hay, and, subliming their phlogistic part, form coal-beds above
and clay below, which are also produced by elutriation; shell-fish in
some morasses, hence shells sometimes found on coals and over iron-
NOTE XVIII ... IRON
Calciform ores; combustion of iron in vital air; steel from deprivation
of vital air; welding; hardness; brittleness like Rupert's drops;
specific levity; hardness and brittleness compared; steel tempered by
its colours; modern production of iron, manganese, calamy; septaria of
iron-stone ejected from volcanos; red-hot cannon balls.
NOTE XIX ... FLINT.
1. _Siliceous rocks_ from morasses; their cements. 2. _Siliceous trees_;
coloured by iron or manganese; Peak-diamonds; Bristol-stones; flint in
form of calcareous spar; has been fluid without much heat; obtained from
powdered quartz and fluor-acid by Bergman and by Achard. 3. _Agates and
onyxes_ found in sand-rocks; of vegetable origin; have been in complete
fusion; their concentric coloured circles not from superinduction but
from congelation; experiment of freezing a solution of blue vitriol;
iron and manganese repelled in spheres as the nodule of flint cooled;
circular stains of marl in salt-mines; some flint nodules resemble knots
of wood or roots. 4. _Sand of the sea_; its acid from morasses; its base
from shells. 5. _Chert or petrosilex_ stratified in cooling; their
colour and their acid from sea-animals; labradore-stone from mother-
pearl. 6. _Flints in chalk-beds_; their form, colour, and acid, from the
flesh of sea-animals; some are hollow and lined with crystals; contain
iron; not produced by injection from without; coralloids converted to
flint; French-millstones; flints sometimes found in solid strata. 7.
_Angles of sand_ destroyed by attrition and solution in steam; siliceous
breccia cemented by solution in red-hot water. 8. _Basaltes and
granites_ are antient lavas; basaltes raised by its congelation not by
NOTE XX ... CLAY.
Fire and water two great agents; stratification from precipitation; many
stratified materials not soluble in water. 1. Stratification of lava
from successive accumulation. 2. Stratifications of limestone from the
different periods of time in which the shells were deposited. 3.
Stratifications of coal, and clay, and sandstone, and iron-ores, not
from currents of water, but from the production of morass-beds at
different periods of time; morass-beds become ignited; their bitumen and
sulphur is sublimed; the clay, lime, and iron remain; whence sand,
marle, coal, white clay in valleys, and gravel-beds, and some ochres,
and some calcareous depositions owing to alluviation; clay from
decomposed granite; from the lava of Vesuvius; from vitreous lavas.
NOTE XXI ... ENAMELS.
Rose-colour and purple from gold; precipitates of gold by alcaline salt
preferable to those by tin; aurum fulminans long ground; tender colours
from gold or iron not dissolved but suspended in the glass; cobalts;
calces of cobalt and copper require a strong fire; Ka-o-lin and
Pe-tun-tse the same as our own materials.
NOTE XXII ... PORTLAND VASE.
Its figures do not allude to private history; they represent a part of
the Elusinian mysteries; marriage of Cupid and Psyche; procession of
torches; the figures in one compartment represent MORTAL LIFE in the act
of expiring, and HUMANKIND attending to her with concern; Adam and Eve
hyeroglyphic figures; Abel and Cain other hyeroglyphic figures; on the
other compartment is represented IMMORTAL LIFE, the Manes or Ghost
descending into Elisium is led on by DIVINE LOVE, and received by
IMMORTAL LIFE, and conducted to Pluto; Tree of Life and Knowledge are
emblematical; the figure at the bottom is of Atis, the first great
Hierophant, or teacher of mysteries.
NOTE XXIII ... COAL.
1. A fountain of fossile tar in Shropshire; has been distilled from the
coal-beds beneath, and condensed in the cavities of a sand-rock; the
coal beneath is deprived of its bitumen in part; bitumen sublimed at
Matlock into cavities lined with spar. 2. Coal has been exposed to heat;
woody fibres and vegetable seeds in coal at Bovey and Polesworth; upper
part of coal-beds more bituminous at Beaudesert; thin stratum of
asphaltum near Caulk; upper part of coal-bed worse at Alfreton; upper
stratum of no value at Widdrington; alum at West-Hallum; at Bilston. 3.
Coal at Coalbrooke-Dale has been immersed in the sea, shewn by sea-
shells; marks of violence in the colliery at Mendip and at Ticknal;
Lead-ore and spar in coal-beds; gravel over coal near Lichfield; Coal
produced from morasses shewn by fern-leaves, and bog-shells, and muscle-
shells; by some parts of coal being still woody; from Lock Neagh and
Bovey, and the Temple of the devil; fixed alcali; oil.
NOTE XXIV ... GRANITE.
Granite the lowest stratum of the earth yet known; porphory, trap, Moor-
stone, Whin-stone, slate, basaltes, all volcanic productions dissolved
in red-hot water; volcanos in granite strata; differ from the heat of
morasses from fermentation; the nucleus of the earth ejected from the
sun? was the sun originally a planet? supposed section of the globe.
NOTE XXV ... EVAPORATION.
I. Solution of water in air; in the matter of heat; pulse-glass. 2. Heat
is the principal cause of evaporation; thermometer cooled by evaporation
of ether; heat given from steam to the worm-tub; warmth accompanying
rain. 3. Steam condensed on the eduction of heat; moisture on cold
walls; south-west and north-east winds. 4. Solution of salt and of blue
vitriol in the matter of heat. II. Other vapours may precipitate steam
and form rain. 1. Cold the principal cause of devaporation; hence the
steam dissolved in heat is precipitated, but that dissolved in air
remains even in frosts; south-west wind. 2. North-east winds mixing with
south-west winds produce rain; because the cold particles of air of the
north-east acquire some of the matter of heat from the south-west winds.
3. Devaporation from mechanical expansion of air, as in the receiver of
an air-pump; summer-clouds appear and vanish; when the barometers sink
without change of wind the weather becomes colder. 4. Solution of water
in electric fluid dubious. 5. Barometer sinks from the lessened gravity
of the air, and from the rain having less pressure as it falls; a
mixture of a solution of water in calorique with an aerial solution of
water is lighter than dry air; breath of animals in cold weather why
condensed into visible vapour and dissolved again.
NOTE XXVI ... SPRINGS.
Lowest strata of the earth appear on the highest hills; springs from
dews sliding between them; mountains are colder than plains; 1. from
their being insulated in the air; 2. from their enlarged surface; 3.
from the rarety of the air it becomes a better conductor of heat; 4. by
the air on mountains being mechanically rarefied as it ascends; 5.
gravitation of the matter of heat; 6. the dashing of clouds against
hills; of fogs against trees; springs stronger in hot days with cold
nights; streams from subterranean caverns; from beneath the snow on the
NOTE XXVII ... SHELL-FISH.
The armour of the Echinus moveable; holds itself in storms to stones by
1200 or 2000 strings: Nautilus rows and sails; renders its shell
buoyant: Pinna and Cancer; Byssus of the antients was the beard of the
Pinna; as fine as the silk is spun by the silk-worm; gloves made of it;
the beard of muscles produces sickness; Indian weed; tendons of rats
NOTE XXVIII ... STURGEON.
Sturgeon's mouth like a purse; without teeth; tendrils like worms hang
before his lips, which entice small fish and sea-insects mistaking them
for worms; his skin used for covering carriages; isinglass made from it;
cavear from the spawn.
NOTE XXIX ... OIL ON WATER.
Oil and water do not touch; a second drop of oil will not diffuse itself
on the preceeding one; hence it stills the waves; divers for pearl carry
oil in their mouths; oil on water produces prismatic colours; oiled cork
circulates on water; a phial of oil and water made to oscillate.
NOTE XXX ... SHIP-WORM.
The Teredo has calcareous jaws; a new enemy; they perish when they meet
together in their ligneous canals; United Provinces alarmed for the
piles of the banks of Zeland; were destroyed by a severe winter.
NOTE XXXI ... MAELSTROM.
A whirlpool on the coast of Norway; passes through a subterraneous
cavity; less violent when the tide is up; eddies become hollow in the
middle; heavy bodies are thrown out by eddies; light ones retained; oil
and water whirled in a phial; hurricanes explained.
NOTE XXXII ... GLACIERS.
Snow in contact with the earth is in a state of thaw; ice-houses; rivers
from beneath the snow; rime in spring vanishes by its contact with the
earth; and snow by its evaporation and contact with the earth; moss
vegetates beneath the snow; and Alpine plants perish at Upsal for want
NOTE XXXIII ... WINDS.
Air is perpetually subject to increase and to diminution; Oxygene is
perpetually produced from vegetables in the sunshine, and from clouds in
the light, and from water; Azote is perpetually produced from animal and
vegetable putrefaction, or combustion; from springs of water; volatile
alcali; fixed alcali; sea-water; they are both perpetually diminished by
their contact with the soil, producing nitre; Oxygene is diminished in
the production of all acids; Azote by the growth of animal bodies;
charcoal in burning consumes double its weight of pure air; every barrel
of red-lead absorbes 2000 cubic feet of vital air; air obtained from
variety of substances by Dr. Priestley; Officina aeris in the polar
circle, and at the Line. _South-west winds_; their westerly direction
from the less velocity of the earth's surface; the contrary in respect
to north-east winds; South-west winds consist of regions of air from the
south; and north-east winds of regions of air from the north; when the
south-west prevails for weeks and the barometer sinks to 28, what
becomes of above one fifteenth part of the atmosphere; 1. It is not
carried back by superior currents; 2. Not from its loss of moisture; 3.
Not carried over the pole; 4. Not owing to atmospheric tides or
mountains; 5. It is absorbed at the polar circle; hence south-west winds
and rain; south-west sometimes cold. _North-east winds_ consist of air
from the north; cold by the evaporation of ice; are dry winds; 1. Not
supplied by superior current; 2. The whole atmosphere increased in
quantity by air set at liberty from its combinations in the polar
circles. _South-east winds_ consist of north winds driven back. _North-
west winds_ consist of south-west winds driven back; north-west winds of
America bring frost; owing to a vertical spiral eddy of air between the
eastern coast and the Apalachian mountains; hence the greater cold of
North America. _Trade-winds_; air over the Line always hotter than at
the tropics; trade-winds gain their easterly direction from the greater
velocity of the earth's surface at the line; not supplied by superior
currents; supplied by decomposed water in the sun's great light; 1.
Because there are no constant rains in the tract of the trade-winds; 2.
Because there is no condensible vapour above three or four miles high at
the line. _Monsoons and tornadoes_; some places at the tropic become
warmer when the sun is vertical than at the line; hence the air ascends,
supplied on one side by the north-east winds, and on the other by the
south-west; whence an ascending eddy or tornado, raising water from the
sea, or sand from the desert, and incessant rains; air diminished to the
northward produces south-west winds; tornadoes from heavier air above
sinking through lighter air below, which rises through a perforation;
hence trees are thrown down in a narrow line of twenty or forty yards
broad, the sea rises like a cone, with great rain and lightning. _Land
and sea breezes_; sea less heated than land; tropical islands more
heated in the day than the sea, and are cooled more in the night.
_Conclusion_; irregular winds from other causes; only two original winds
north and south; different sounds of north-east and south-west winds; a
Bear or Dragon in the arctic circle that swallows at times and
disembogues again above one fifteenth part of the atmosphere; wind-
NOTE XXXIV ... VEGETABLE PERSPIRATION.
Pure air from Dr. Priestley's vegetable matter, and from vegetable
leaves, owing to decomposition of water; the hydrogene retained by the
vegetables; plants in the shade are _tanned_ green by the sun's light;
animal skins are _tanned_ yellow by the retention of hydrogene; much
pure air from dew on a sunny morning; bleaching why sooner performed on
cotton than linen; bees wax bleached; metals calcined by decomposition
of water; oil bleached in the light becomes yellow again in the dark;
nitrous acid coloured by being exposed to the sun; vegetables perspire
more than animals, hence in the sun-shine they purify air more by their
perspiration than they injure it by their respiration; they grow fastest
in their sleep.
NOTE XXXV ... VEGETABLE PLACENTATION.
Buds the viviparous offspring of vegetables; placentation in bulbs and
seeds; placentation of buds in the roots, hence the rising of sap in the
spring, as in vines, birch, which ceases as soon as the leaves expand;
production of the leaf of Horse-chesnut, and of its new bud; oil of
vitriol on the bud of Mimosa killed the leaf also; placentation shewn
from the sweetness of the sap; no umbilical artery in vegetables.
NOTE XXXVI ... VEGETABLE CIRCULATION.
Buds set in the ground will grow if prevented from bleeding to death by
a cement; vegetables require no muscles of locomotion, no stomach or
bowels, no general system of veins; they have, 1. Three systems of
absorbent vessels; 2. Two pulmonary systems; 3. Arterial systems; 4.
Glands; 5. Organs of reproduction; 6. muscles. I. Absorbent system
evinced by experiments by coloured absorptions in fig-tree and picris;
called air-vessels erroneously; spiral structure of absorbent vessels;
retrograde motion of them like the throats of cows. II. Pulmonary
arteries in the leaves, and pulmonary veins; no general system of veins
shewn by experiment; no heart; the arteries act like the vena portarum
of the liver; pulmonary system in the petals of flowers; circulation
owing to living irritability; vegetable absorption more powerful than
animal, as in vines; not by capillary attraction.
NOTE XXXVII ... VEGETABLE RESPIRATION.
I. Leaves not perspiratory organs, nor excretory ones; lungs of animals.
1. Great surfaces of leaves. 2. Vegetable blood changes colour in the
leaves; experiment with spurge; with picris. 3. Upper surface of the
leaf only acts as a respiratory organ. 4. Upper surface repels moisture;
leaves laid on water. 5. Leaves killed by oil like insects; muscles at
the foot-stalks of leaves. 6. Use of light to vegetable leaves;
experiments of Priestley, Ingenhouze, and Scheel. 7. Vegetable
circulation similar to that of fish. II. Another pulmonary system
belongs to flowers; colours of flowers. 1. Vascular structure of the
corol. 2. Glands producing honey, wax, &c. perish with the corol. 3.
Many flowers have no green leaves attending them, as Colchicum. 4.
Corols not for the defence of the stamens. 5. Corol of Helleborus Niger
changes to a calyx. 6. Green leaves not necessary to the fruit-bud;
green leaves of Colchicum belong to the new bulb not to the flower. 7.
Flower-bud after the corol falls is simply an uterus; mature flowers not
injured by taking of the green leaves. 8. Inosculation of vegetable
NOTE XXXVIII ... VEGETABLE IMPREGNATION.
Seeds in broom discovered twenty days before the flower opens; progress
of the seed after impregnation; seeds exist before fecundation; analogy
between seeds and eggs; progress of the egg within the hen; spawn of
frogs and of fish; male Salamander; marine plants project a liquor not a
powder; seminal fluid diluted with water, if a stimulus only? Male and
female influence necessary in animals, insects, and vegetables, both in
production of seeds and buds; does the embryon seed produce the
surrounding fruit, like insects in gall-nuts?
NOTE XXXIX ... VEGETABLE GLANDULATION.
Vegetable glands cannot be injected with coloured fluids; essential oil;
wax; honey; nectary, its complicate apparatus; exposes the honey to the
air like the lacrymal gland; honey is nutritious; the male and female
parts of flowers copulate and die like moths and butterflies, and are
fed like them with honey; anthers supposed to become insects;
depredation of the honey and wax injurious to plants; honey-dew; honey
oxygenated by exposure to air; necessary for the production of
sensibility; the provision for the embryon plant of honey, sugar,
starch, &c. supplies food to numerous classes of animals; various
vegetable secretions as gum tragacanth, camphor, elemi, anime,
turpentine, balsam of Mecca, aloe, myrrh, elastic resin, manna, sugar,
wax, tallow, and many other concrete juices; vegetable digestion;
chemical production of sugar would multiply mankind; economy of nature.