which duft feems to be attracted from the circumambient air.

Now we know that the rain, even in our hotteft days, comes from a very cold region. Its falling fometimes in the form of ice, fhews this clearly; and perhaps even the rain is fnow or ice when it first moves downwards, though thawed in falling: And we know that the drops of rain are often electrified: But thofe caufes of addition to each drop of water, or piece of hail, one would think could not long continue to produce the fame effect; fince the air, through which the drops fall, muft foon be ftript of its previously diffolved water, fo as to be no longer capable of augmenting them. Indeed very heavy showers, of either, are never of long continuance; but moderate rains often continue fo long as to puzzle this hypothefis : So that upon the whole I think, as I intimated before, that we are yet hardly ripe for making one."

VOL. II.

I

SPECULA

SPECULATIONS on the PERCEPTIVE POWER of VEGETABLES. By THOMAS PERCIVAL, M.D. F. R. S. &c. &c. Read February 18, 1784.

These are not idle, philofophic dreams;

Full Nature teems with life. -

THOMSON'S Spring, Second Edit. line 136.*

'N all our enquiries into truth, whether natural

IN

or moral, it is neceffary to take into previous confideration, the kind of evidence which the fubject admits of; and the degree of it, which is fufficient to afford fatisfaction to the mind. Demonstrative evidence is abfolute, and without gradation; but probable evidence afcends, by regular steps, from the lowest prefumption, to the highest moral certainty. A fingle prefumption is, indeed, of little weight; but a feries of fuch imperfect proofs may produce the fulleft conviction. The strength of belief, however, may often be greater, than is proportionate to the force and number of these proofs, either individually or collectively confidered. For, as uncertainty is always painful to the understanding, very flight evidence, if the fubject

*Thefe lines are omitted in the fubfequent editions of Thomfon's Seafons.

be

be capable of no other, fometimes amounts to credibility. This every philofopher experiences, in his researches into nature; and the observation may ferve as an apology for the following jeu d'efprit; in which I fhall attempt to fhew, by the feveral analogies of organization, life, inftinct, fpontaneity, and felf-motion, that plants, like animals, are endued with the powers, both of perception and enjoyment.

I. Vegetables bear fo near a fimilitude to animals in their STRUCTURE, that botanists have derived from anatomy and phyfiology, almost all the terms employed in the description of them. A tree or fhrub, they inform us, confifts of a cuticle, cutis, and cellular membrane; of veffels varioufly difpofed, and adapted to the tranfmiffion of different fluids; and of a ligneous, or bony fubftance, covering and defending a pith or marrow. Such organization evidently belongs not to inanimate matter; and when we obferve, in vegetables, that it is connected with, or inftrumental to the powers of growth, of felf-prefervation, of motion, and of feminal increase, we cannot hesitate to afcribe to them a LIVING PRINCIPLE. And by admitting this attribute, we advance a step higher in the analogy we are pursuing. For, the idea of life naturally implies fome degree of perceptivity: And wherever perception refides, a greater or lefs

I 2

lefs capacity for enjoyment feems to be its neceffary adjunct. Indefinite and low, therefore, as this capacity may be, in each fingle herb or tree, yet, when we confider the amazing extent of the vegetable kingdom, "from the cedar of Lebanon to the hyffop upon the wall," the aggregate of happinefs, produced by it, will be found to exceed our most enlarged conceptions. It is prejudice only, which restrains or fuppreffes the delightful emotions, refulting from the belief of fuch a diffufion of good. And, because the framers of systems have invented arrangements and divifions of the works of God, to aid the mind in the pursuits of science, we implicitly admit as reality, what is merely artificial; and adopt diftinctions, without proof of any effential difference. Lapides crefcunt; vegetabilia crefcunt et vivunt; animalia crefcunt, vivunt, et fentiunt. This climax, of Linnæus, is conformable to the doctrines of Ariftotle, Pliny, Jungius, and others: But none of thefe great men have adduced fufficient evidence, to fupport the negative characteristics, if I may fo exprefs myself, on which the three kingdoms of nature are here established. That a gradation fubfifts, in the scale of beings, is clearly manifeft; but the higher advances we make in phyfical knowledge, the nearer will the degrees be feen to approach each other. And it is no very extravagant conjecture to fuppofe, that, in fome future period, perceptivity

may

may be discovered to extend, even beyond the limits now affigned to vegetable life. Corallines, madrepores, millepores, and fpunges were formerly confidered as foffil bodies: But the experiments of Count Marfigli evinced, that they are endued with life, and led him to clafs them with the maritime plants. And the obfervations of Ellis, Juffieu and Peyfonel, have fince raised them to the rank of animals.* The detection of error, in long established opinions concerning one branch of natural knowledge, juftifies the fufpicion of its existence in others, which are nearly allied to it: And it will appear, from the profecution of our enquiry into the instincts, fpontaneity, and felf-moving power of vegetables, that the fufpicion is not without foundation.

II. INSTINCT is a propenfity, or movement to feek, without deliberation, what is agreeable to the particular nature, actuated by it; and to avoid what is incongruous, or hurtful. It is a practical power, which requires no previous knowledge or experience; and which pursues a present or future good, without any definite ideas or forefight; and often, with very faint degrees of consciousness. The calf, when it first comes into the world, applies to the teats of the cow, utterly ignorant of the tafte, or nutritious quality of the milk, and confequently,

Confult Philof. Tranfa&t. Amænitat. Academic. and Bishop Watfon on the Subjects of Chemistry. I 3

with