_Of Change of_ SPECIES.
I. _That Plants of the most different Nature feed on the same Sort of
Food._
II. _That there is no Plant but what must rob any other Plant within
its Reach._
III. _That a Soil which is proper to one Sort of Vegetable once, is,
in Respect of the Sort of Food it gives, proper to it always._
If any one of these _Three Propositions_ be true, as I hope to prove
all of them are, then it will follow, that there is no need to change
the Species of _Vegetables_ from one Year to another, in respect to the
different Food the same Soil is, tho’ falsely, supposed to yield[201].
[201] For if all Plants rob one another, it must be because they all
feed on the same Sort of Food; and, admitting they do, there can
be no Necessity of changing the Species of them, from one Soil to
another; but the same Quantity of the same Food, with the same Heat
and Moisture which maintains any Species one Year, must do it any
other Year.
The common Opinion is contrary to all these (as it must be, if contrary
to any one of them): And since an Error in this fundamental Principle
of _Vegetation_ is of very ill Consequence; and since Dr. _Woodward_,
who has been serviceable in other respects[202] to this Art, has
unhappily fallen in with the Vulgar in this Point; his Arguments for
this Error require to be answer’d in the first Place.
[202] By proving, in his Experiments, that Earth is the _Pabulum_ of
Plants.
The Doctor says[203] ‘It is not possible to imagine how one uniform,
homogeneous Matter, having its Principles, or original Parts, all of
the same Substance, Constitution, Magnitude, Figure, and Gravity,
should ever constitute Bodies so egregiously _unlike_, in all those
Respects, as Vegetables of different Kinds are; nay, even as the
different Parts of the _same_ Vegetable.’
[203] In _Philos. Trans._ No. 253.
‘That there should be that vast Difference in them, in their several
Constitutions, Makes, Properties, and Effects, and yet all arise from
the very same Sort of Matter, would be very strange.’
_Answer._ ’Tis very probable, that the terrestrial Particles which
constitute _Vegetables_, tho’ inconceivably minute, may be of great
Variety of Figure, and other Differences; else they could not be
capable of the several Ferments, _&c._ they must undergo in the Vessels
of Plants. Their Smalness can be no Objection to their Variety, since
even the Particles of Light are of various Kinds.
But as the Doctor asserts, ‘That each Part of the same _Vegetable_
requires a peculiar specific Matter for its Formation and Nourishment;
and that there are very many and different Ingredients to go to the
Composition of the same individual Plants;’
From hence must be inferred, that the same Plant takes in very many
and different Ingredients (and it is proved, that no Plant refuses
any Ingredient[204] that is capable of entering its Roots. Tho’ the
terrestrial Particles which nourish _Vegetables_, be not perfectly
homogeneous; yet most of the various Tastes and Flavours of Plants are
made in and by the Vessels[205].
[204] Dr. _Grew_, in his Anatomy of Plants, by microscopical
Inspection, found, that the outer Superficies of Roots was of a
spongy Substance; and ’tis well known, that no such Body can refuse
to imbibe whatever Liquor comes in Contact with it, but will by its
springy Porosity absorb any sort of Moisture.
[205] We are convinced, that ’tis the Vessels of Plants that make the
different Flavours; because there is none of these Flavours in the
Earth of which they are made, until that has enter’d and been alter’d
by the vegetable Vessels.
Doctor _Woodward_ says, ‘That Water will pass Pores and Interstices,
that neither Air, nor any other Fluid, will: This enables it to
enter the finest Tubes and Vessels of Plants, and to introduce the
terrestrial Matter, conveying it to all Parts of them; whilst each,
by means of Organs ’tis endow’d with for the Purpose, intercepts,
and assumes into itself, such Particles as are suitable to its own
Nature[206]; letting the rest pass on _through the common Ducts_.’
[206] If the Doctor’s Plants were so nice in leaving vegetable Matter
_behind, quiet and undisturb’d_, ’tis a Wonder they would take up the
mineral Matter, as, he says, they did, that kill’d themselves with
Nitre.
These Plants might, with much less Difficulty, have distinguish’d the
mineral Matter from the vegetable Matter, than they could distinguish
the different Particles of vegetable Matter from one another, and
must have been very unwise to chuse out the Nitre (their Poison) from
the Water and Earth, and to leave the vegetable Particles behind;
none of which could be so improper to them as the Nitre.
It may perhaps be objected, that such like pernicious Matter kills a
Plant by only destroying its Roots, and by closing the Pores; which
prevents the Nourishment from entering to maintain its Life; and that
such Matter doth not itself enter to act as Poison upon the Sap, or
upon the Vessels of the Body, or Leaves: But it plainly appears that
it doth enter, and act as Poison; for when some of the Roots of a
Mint, growing in Water, are put into salt Water, it kills the whole
Plant, although the rest of the Roots remaining in the fresh Water
were sufficient to maintain it, if the other Roots had been cut off
at the Time they were removed into the Salt Water; and also all the
Leaves, when dead, will be full of Salt.
Or if the Juice of wild Garlick-seed be made use of instead of the
salt Water, it will have the same Effect; and every one of the
Mint-leaves will have a strong Taste of Garlick in it.
Here then he says plainly, That each Plant receives the terrestrial
Matter in gross, both suitable and unsuitable to its Nature, retains
the suitable Particles for its Augment, and the unsuitable lets pass
through it. And in another Place he says they are exhal’d into the
Atmosphere.
And this will appear to be the true Case of Plants; and directly
contradicts what he advances, in saying, ‘That each Sort of Grain takes
forth that peculiar Matter that is proper for its own Nourishment.
First, the Wheat draws off those Particles that suit the Body of that
Plant, _the rest lying all quiet and undisturb’d the while_. And when
the Earth has yielded up all them, those that are proper for Barley, a
different Grain, remain still behind, till the successive Crops of that
Corn fetch them forth too; and so the Oats and Pease in their turn,
till, in fine, all is carried off.’
In the former Paragraph he says, each Plant _lets pass through it_
the rest of the Particles that are not suitable to its own Nature. In
the latter Paragraph he says, That each _leaves_ the unsuitable _all
behind_ for another Sort; and so on.
Both cannot be true.
If the latter were true, Change of Sorts would be as necessary as it is
commonly thought. But if the former be true, as I hope to prove it is,
then there can be no Use of changing of Sorts in Respect of different
Nourishment.
If in this Series of Crops each Sort were so just as to take only such
Particles, as are peculiarly proper to it, letting all the rest alone
to the other Sorts to which they belonged, as the Doctor imagines;
then it would be equal to them all, which of the Sorts were sown first
or last: But let the Wheat be sown after the Barley, Pease, and Oats,
instead of being sown before them, and then it would evidently appear,
by that starv’d Crop of Wheat, either that some or all of those other
Grains had violated this natural Probity, or else that Nature has
given to _Vegetables_ no such Law of _Meum_ and _Tuum_[207].
[207] A Charlock could not rob a Turnep, and starve it, more than
several Turneps can do, unless the Charlock did take from it the same
Particles which would nourish a Turnep; and unless the Charlock did
devour a greater Quantity of that Nourishment than several Turneps
could take.
Flax, Oats, and Poppy, could not burn or waste the Soil, and make it
less able to produce succeeding Crops of different Species, unless
they did exhaust the same Particles which would have nourish’d Plants
of different Species: For let the Quantity of Particles these Burners
take be never so great, the following Crops would not miss them, or
suffer any Damage by the Want or Loss of them, were they not the same
Particles which would have nourished those Crops, if the Burners had
left them _behind, quiet and undisturbed_. Neither could Weeds be of
any Prejudice to Corn, if they did draw off those Particles only that
suit the Bodies of Weeds, _the rest lying all quiet and undisturbed
the while_. But constant Experience shews, that all Sorts of Weeds,
more or less, diminish the Crop of Corn.
If these Things were, as the Doctor affirms, why do Farmers lose a
Year’s Rent, and be at the Charge of fallowing and manuring their
Land, after so few Crops; since there are many more Sorts of Grain as
different from these and one another, as those are which they usually
sow?
They still find, that the first Crops are best; and the longer they
continue sowing, the worst the last Crops will prove, be they of never
so different a Species; unless the Land were not in so good Tilth for
the first Crop as for the subsequent; or unless the last sown be of a
more robust Species.
This Matter might be easily clear’d, could we perfectly know the Nature
of those supposed _unsuitable_[208] _Particles_; but, in Truth, there
is no more to be known of such of them, than that they are carried
away by the Atmosphere to a Distance, according to the Velocity of the
Air; perhaps several Miles off, at least, never like to return to the
Spot of Ground from whence the Plants have raised them.
[208] But we must not conclude, that these Particles, which pass
through a Plant (being a vastly greater Quantity than those that
abide in it for its Augment), are all unsuitable, because no one of
them happens to hit upon a fit _Nidus_: For since the Life of Animals
depends upon that of Plants, ’tis not unreasonable to imagine, that
Nature may have provided a considerable Overplus for maintaining the
Life of individual Plants, when she has provided such an innumerable
Overplus for continuing every Species of Animals.
But suppose these cast-off Particles were, when taken in, unfit for the
Nourishment of any manner of Vegetables: Then the Doctor must fansy
the Wheat to be of a very scrupulous Conscience, to feed on these
Particles, which were neither fit for its own Nourishment, nor of
any other Plant; and at the same time to forbear to take the Food of
Barley, Pease, and Oats, letting that _lie still and undisturb’d the
while_, as he says it does, tho’ he gives no manner of Reason for it.
’Tis needless to bring stronger Arguments, than the Doctor’s
Experiments afford, against his own vulgar Opinion, of Plants
distinguishing the particular Sort of terrestrial Matter, that, he
says, is proper to each Sort of _Vegetable_, in these Words; _viz._
‘Each Sort takes forth that peculiar Matter that is proper for its own
Nourishment, the _rest lying all quiet and undisturb’d the while_.’
He says, that great Part of the terrestrial Matter, mixed with the
Water, passes up into the Plant along with it; which it could not do,
if only the peculiar Matter, proper to each Plant, did pass up into
it: And after he has shewed how apt the vegetable Matter is to attend
Water in all its Motions, and to follow it into each of its Recesses;
being by no Filtrations or Percolations wholly separable from it; ’tis
strange he should think that each Plant leaves the greatest Part of it
behind, separated from the Water which the Plant imbibes.
There are, doubtless, more than a Million of Sorts of Plants, all of
which would have taken up the Water, and had each as much Right to its
Share, or proper Matter in it, as the Doctor’s Plants had; and then
there would be but a very small (or a Millionth) Part of it proper to
each of his Plants: And these leaving all the rest behind, both of the
Water wherewith the Glasses at first were filled, when the Plants were
put into them; and also of all the additional Water daily supply’d into
them afterwards; I say, so much more terrestrial Matter brought into
these Glasses, in Proportion to the added Water, and so very small
a Part as could be proper to each of his plants being carried off;
there must have remain’d in these Glasses a much greater Quantity of
terrestrial Matter at the End of the Experiment, than remained in the
Glasses _F_ or _G_, which had no Plants in them, nor any Water added
to, or diminished from them; but the quite contrary appear’d. ‘And
the Water in the Glasses _F_ and _G_, at the End of the Experiment,
exhibited a larger Quantity of terrestrial Matter, than any of those
that had Plants in them did. The Sediment at the Bottom of the Glasses
was greater, and the _Nubeculæ_ diffused thro’ the Body of the Water
thicker.’ Had the _Cataputia_ insum’d, with the Two thousand Five
hundred and One Grains of Water, no more than its proper Share of the
vegetable Matter, it could not have attained thence an Increase of
Three Grains and a Quarter, nor even the Thousandth Part of One Grain.
But he found ‘this terrestrial Matter, contained in all Water, to be of
Two Kinds: The one properly, a vegetable Matter, but consisting of very
different Particles; some of which are proper for the Nourishment of
some kind of Plants, others for different Sorts,’ _&c._
This, indeed, would have been a most wonderful Discovery, and might
have given us a great Light, if he had told us in what Language and
Character these proper Differences were stamp’d or written upon the
vegetable Particles; which Particles themselves, he says, were scarce
visible. Certainly it must be a great Art (much beyond that of Dr.
_Wallis_) to decypher the Language of Plants, from invisible Characters.
But that this Dream may deceive none, except such who are very fond
of old Errors, there is an _Experimentum Crucis_ which may convince
them; _viz._ At the proper Season, tap a Birch-tree in the Body or
Boughs, and you may have thence a large Quantity of clear Liquor, very
little altered from Water; and you may see, that every other Species
of Plants, that will grow in Water, will receive this; live and grow
in it, as well as in common Water. You may make a like Experiment by
tapping other Trees, or by Water distilled from Vegetables; and you
will find no Species of Plants, into which this Water will not enter,
and pass through it, and nourish it too; unless it be such a Species as
requires more Heat than Water admits; or unless the peculiar Vessels
of that it has first passed through, have so altered the vegetable
Particles contained in that Water, as that it acts as Poison upon some
other particular Species.
The Doctor concludes, ‘That Water is only the Agent that conveys
the Vegetable Matter to the Bodies of Plants, that introduces and
distributes it to their several Parts for their Nourishment: That
Matter is sluggish and inactive, and would lie eternally confin’d to
its Beds of Earth, without ever advancing up into Plants, did not
Water, or some like Instrument, fetch it forth, and carry it unto them.’
That Water is very capable of the Office of a Carrier to Plants, I
think the Doctor has made most evident; but as to the Office of such
an Agent as his Hypothesis bestows upon it, it seems impossible to
be executed by Water. For it cannot be imagined, that Water, being
itself but mere homogenial Matter, void of all Degrees of Life, should
distinguish each Particle of vegetable Matter, proper and peculiar to
every different Species of Plants, which are innumerable; and when ’tis
to act for the Wheat, to find out all the Particles proper to that sort
of Grain, to rouse only those particular Sluggards from their Beds of
Earth, letting all the rest lie quiet and undisturbed the while. This
Agent frees the Wheat-Particles from their Confinement, and conveys,
introduces, and distributes them, and only them, into the several Parts
of the Wheat.
Since ’tis unreasonable to believe, that Water can have such
extraordinary Skill in Botany, or in Micrography, as to be qualified
for a sufficient Agent in such an abstruse Matter, I conceive Water
to be only an Instrument or Vehicle, which takes up indifferently any
Particles it meets with (and is able to carry), and advances them
(or the _Pabulum_ they yield) up into the First Plant, whose Root it
comes in Contact with; and that every Plant it meets with does accept
thereof, without distinguishing any different Sorts or Properties
in them, until they be so far introduc’d and advanc’d up into the
vegetable Vessels, that it would be in vain to distinguish them; for
whether the terrestrial Matter, Plants imbibe with the Water, will kill
or nourish them, appears by its Effects; but which cannot be foreknown
or prevented without the Help of Faculties, which Plants are not
endow’d with.
Mr. _Bradley_ seems to have carried this Error farther than any Author
ever did before; but he supports it by Affirmations only, or by such
Arguments (I cannot say Reasons; for no Reason can be against any
Truth) as go near to confute the very Opinion he pretends to advance by
them.
He ascribes to Vegetables the Sense of Taste, by which he thinks
they take such Nourishment as is most agreeable to their respective
Natures, refuting the rest; and will rather starve, than eat what is
disagreeable to their Palate.
In the Preface to his _Vol._ I. _Page_ 10. of his _Husbandry_ and
_Gardening_, he says, ‘They feed as differently as Horses do from Dogs,
or Dogs from Fish.’
But what does he mean by this Instance, _Vol._ I. _p._ 39. _viz._ ‘That
Thyme, and other Aromatics, being planted near an Apricot-tree, would
destroy that Tree?’ Does it not help to confirm, that every Plant does
not draw exactly the same Share of Nourishment?
I believe there is no need for him to give more Instances to disprove
his Assertion than this one. His Conclusion, taken by itself, is so far
right; _viz._ ‘That if the Nourishment the Earth afforded to the Thyme
and Apricot-tree, had been divided into Two Shares, both could not have
had them.’
But this his Instance proves, That those Aromatics robb’d the
Apricot-tree of so much of its Share as to starve it; and that they,
tho’ of so very different a Nature, did draw from the Earth the same
Nourishment which the Apricot-tree should have taken for its Support,
had not the Aromatics been too hard for it, in drawing it off for their
own Maintenance:
Unless he believes, that all the Juices of the Aromatics were as
Poison to the Apricot; and that, according to my Experiment of the
Mint, some of their Roots might discharge some kind of Moisture in dry
Weather, given them by others, that had it for their Use; and that the
Apricot-roots, mingling with them, might imbibe enough of that Liquor,
altered sufficiently by their Vessels, to poison and kill the Tree.
But then, where was the Tree’s distinguishing Palate? Why did it not
refuse this Juice, which was so disagreeable as to kill it? And as to
his Notion of Vegetables having Palates, let us see how it agrees with
what he affirms.
‘That ’tis the Vessels of Plants that make, by their Filtrations,
Percolations, _&c._ all the different Tastes and Flavours of the
Matter, which is the Aliment of Plants; and that, before it be by them
so filtred, _&c._ it is only a Fund of insipid Substance, capable of
being altered by such Vessels, into any Form, Colour, or Flavour.’
And _Vol._ I. _p._ 38. ‘The different Strainers, or Vessels of the
several Plants, growing upon that Spot of Earth, thus impregnated with
Salts, alter those Salts or Juices, according to the several Figures or
Dimensions of their Strainers; so that one Plant varies, in Taste and
Smell, from others, tho’ all draw their Nourishment from the same Stock
lodged in the Earth.’ See Mr. _Bradley_’s _Palates of Plants_, and the
insipid Substance he allots them to distinguish the Taste of, how they
agree.
They must, it seems, within their own Bodies, give the Flavour to this
insipid Substance, before their Palates can be of any Use; and, even
then, ’tis impossible to be of any Use, but in the manner of the Dog
returning to his Vomit.
They would have as much Occasion for the Sense of Smelling, as of
Taste; but, after all, of what Use could either of the Two be to
Plants, without local Motion of their Roots? which they are so
destitute of, that no Mouth of a Root can ever remove itself from
the very Point where it was first formed, because a Root has all its
longitudinal Increase at the very End; for, should the Spaces betwixt
the Branchings increase in Length, those Branches would be broken
off, and left behind, or else drawn out of their Cavities; which must
destroy the Plant. All the Branches, except the foremost, would be
found with their Extremities pointing towards the Stem; the contrary
of which Posture they are seen to have: And if they moved backwards,
that would have much the same Effect on all the collateral Branchings
to destroy them. Smell and Taste then could be of no manner of Use to
Vegetables, if they had them; they would have no Remedy or Possibility
to mend themselves from the same Mouths, removing to search out other
Food, in case they had Power to dislike or refuse what was offered them.
Therefore the crude Earth, being their Food, simple and free from
any Alterations by Vessels, remaining insipid, cannot give, neither
can Plants receive, require, or make use of, any Variety from it, as
Animals do from their Diet. It would be lost upon them, and Nature
would have acted in vain, to give Smell and Taste to Vegetables, and
nothing but insipid Earth for an Object of them; or to give them a
charming Variety of Relish and Savour in their Food, without giving
them Senses necessary to perceive or enjoy them; which would be like
Light and Colours to the Blind, Sound and Music to the Deaf, or like
giving Eyes and Ears to Animals, without Light or Sound to affect them.
The Mouths of Plants, situate in the convex Superficies of Roots, are
analogous to the Lacteals, or Mouths, in the concave Superficies of the
Intestines of Animals.
These spongy Superficies of animal Guts, and vegetable Roots, have no
more Taste or Power of refusing whatever comes in Contact with them,
the one than the other.
The free open Air would be equally injurious to both; and if exposed
to it, it would dry and close up the fine Orifices in Guts and Roots:
Therefore Nature has guarded both from it.
Nature has also provided for the Preservation of both Vegetables and
Animals (I do not say equally) in respect of their Food; which might
poison them, or might not be fit to nourish them.
The Security of Plants (the best that can be) is their Food itself,
Earth; which, having been altered by no Vessels, is always safe and
nourishing to them; For a Plant is never known to be poisoned by its
own natural Soil, nor starved, if it were enough of it, with the
requisite Quantities of Heat and Moisture.
Roots, being therefore the Guts of Plants, have no need to be guarded
by Senses; and all the Parts and Passages, which serve to distinguish
and prepare the Food of Animals, before it reach the Guts, are omitted
in Plants, and not at all necessary to them.
But as the Food of most Animals is Earth, very variously changed and
modified by vegetable or animal Vessels, or by both, and some of it is
made wholsome, some poisonous; so that if this doubtful Food should be
committed to the Intestines, without Examination, as the pure unaltered
Earth is to Roots, there would, in all Probability, be very few Animals
living in the World, except there be any that feed on Earth at first
Hand only, as Plants do.
Therefore, lest this Food, so much more refined than that of Plants,
should, by that very means, become a fatal Curse, instead of a Blessing
to Animals, Nature has endowed them with Smell and Taste, as Sentinels,
without whose Scrutiny these various uncertain Ingredients are not
admitted to come where they can enter the Lacteals, and to distinguish,
at a sufficient Distance, what is wholsome and friendly, from what is
hurtful; for when ’tis once passed out of the Stomach into the Guts,
’tis too late to have Benefit from Emetics; its Venom must then be
imbibed by the Lacteal Mouths, and mix with the Blood, as that must
mix with the Sap, which comes in Contact with the Lacteals in the
Superficies of Roots, Nature having left this unguarded.
Yet Plants seem to be better secured by the Salubrity and Simplicity
of their Food, than Animals are by their Senses: To compensate that
Inequality of Danger; Animals have Pleasure from their Senses, except
some miserable Animals (and such there are) that have more Pain than
Pleasure from them. But I suppose, more Animals than Plants are
poison’d; and that a poisonous Animal is less fatal to a Plant, than a
poisonous Plant is to an Animal.
It being sufficiently proved, that every sort of Vegetables, growing
in the same Soil, takes, and is nourished, by the same Sort of Food;
it follows from hence, that the beneficial Change of Sorts of Seeds or
Plants, we see in the common Husbandry, is not from the Quality of the
Sorts of Food, but from other Causes; such as,