Under these circumstances I shall beg your candid attention to a new view of the subject, and a view that may tend to give us a more definite idea of the nature of the action, and consequently of the extent and real meaning of the term.

In an early lecture of the preceding series* I have endeavoured to point out the common or essential, and many of the peculiar properties of inorganic matter; and in a subsequent study† I attempted to lay down the more prominent characters by which inorganic is distinguished from organic matter, as a stone, for example, from a plant or an animal. I observed that, on investigating the history of the stone, it would be found to have been produced fortuitously; to have grown by external accretion, and only to be destructible by chemical or mechanical means: while, on investigating the history of the plant or the animal, it would be found to have been produced by generation; to have grown by nutrition, or internal instead of external accretion; and to be destructible by death; to be actuated by an internal power, and possessed of parts mutually dependent, and contributing to each other's functions. I observed farther, that in what this internal power consists we know not: that in plants and animals it appears to be somewhat differently modified, but that wherever we meet with it we term it the PRINCIPLE OF LIFE, and characterize the individual substance it actuates by the name of an organized being, from its possession of organized parts, in contradistinction to all those substances which are destitute as well of life as of internal organs, and which are hence denominated unorganized.

Upon another occasion I took a brief survey of the chief theories which have been offered upon the nature of this mysterious and fugitive essence:‡ which I observed was altogether a distinct principle from that of thought, and from that of sensation, for both these must also be kept distinguished from each other. I have remarked, that in modern times it had at one period been said to be derived from caloric, thermogene, or the elementary matter of heat, as it exists in the organized system from the well ascertained importance of this substance (if it be a substance) towards the perfection, and even the continuance of all the vital funtions: that at another time it was, for the same reason, supposed to consist of oxygene introduced into the system by every act of inspiration; and still more lately of the Voltaic aura, in consequence of those wonderful effects which this aura is now well known to produce on the muscular fibres of animals, not only during life, but often for some hours after death has taken place. I remarked

Dr. Hancock has trodden over an extensive ground of both physical and metaphysical research, and the excellent spirit with which he writes, entitles him to the esteem of every good man. Yet I am at a loss to determine why the principle of reason, or the reasoning soul in man, should not have as fair a claim to originate from the divine energy that pervades every part of nature, from the minutest atom to the highest spiritual afflation, as the faculty of instinct. By throwing, however, the principle of human reason out of the general pale, and by associating instinct with the high alliances just adverted to, the "unconscious intelligence," as Dr. Hancock has denominated it, of the lowest part of the animal creation, even that of insects and worms, is raised to a loftier and diviner rank than the peculiar principle by which man has hitherto been supposed to exercise a dominion over the rest of creation. "In the lowest order of animals,” says Dr. Hancock, “the divine energy seems to act with most unimpeded power. It is less and less concentrated in the successive links of the living chain upward to man.-The lowest animal has this divine power, not of free choice, nor conaciously: the HOLIEST of men has it also, but consciously and willingly; and it then becomes his ruling principle; his divine counsellor; his never-failing help; a light to his feet, and a lantern to his path,"-Essay on Instinct, and its Physical and Moral Relations, p. 170-513. Ser. I. Lect. IV. † Ser. I. Lect. VIII. 1 Ser. I. Lect. X.

farther, that Mr. John Hunter had traced this living principle to many of the organized fluids, as well as to the solids; and that he had especially developed it in the blood, which, coincidently with the Mosaic declaration, he believed to be its immediate seat. "The difficulty," observes he, "of conceiving that the blood is endowed with life while circulating, arises merely from its being a fluid; and the mind not being accustomed to the idea of a living fluid."* And I observed, that by a variety of important and welldefined experiments, this enterprising and indefatigable indagator had succeeded in proving, not only that it contributes in a greater degree to the vital action and to the vital material of the general system than any other constituent part of it, whether solid or fluid, but has all the essential properties of life; that it is capable of being acted upon, and contracting, like the muscular fibre, upon the application of an appropriate stimulus, as atmospheric air, for example; on which occasion it becomes constringed into that cake or coagulum which every one must have beheld in blood drawn from the arm: that in all degrees of atmospherical temperature, of heat or cold, which the body is capable of enduring, it maintains an equality in its own temperature with scarcely any variation: that in the case of paralytic limbs it is the only power that continues vitality in them and preserves them from corruption; that though not vascular itself, it is capable by its own energy of producing new vessels out of its own substance, and vessels too, of every description, lymphatics, arteries, and even nerves; and finally, that though like the muscular fibre, it is capable of contracting upon the application of a certain degree of appropriate stimulus, like the muscular fibre, also, it is instantly exhausted of its vital power whenever such stimulus is excessive; and that the stroke of lightning which destroys the muscular fibre, and leaves it flaccid and incontractile, destroys likewise the blood, and leaves it loose and incoagulable.

In every organized system, then, whether animal or vegetable, and in every part of such system, whether solid or fluid, we trace an evident proof of that controlling and identifying power which physiologists have denominated, and with much propriety, the PRINCIPLE OF life. Of its cause and nature we know no more than we do of the cause and nature of gravitation or magnetism. It is neither essential mind nor essential matter; it is neither passion nor sensation; but though unquestionably distinct from all these, is capable of combining with any of them: it is possessed of its own book of laws, to which, under the same circumstances, it adheres without the smallest deviation: and its sole and uniform aim, whether acting generally or locally, is that of health, preservation, or reproduction. The agency by which it operates is that which we denominate or should denominate INSTINCT, and the actions by which its sole and uniform aim is accomplished are what we mean or should mean by INSTINCTIVE ACTIONS; or to speak somewhat more precisely, instinct is the operation of the living principle, whenever manifestly directing its operations to the health, preservation, or reproduction of a living frame, or any part of such frame.t

The law of instinct, then, is the law of the living principle: instinctive

* Essay on the Blood, &c. p. 20.

†This lecture was delivered January 1813; and Mr. Keith, on Tuesday, December 7, 1813, had a valuable paper read before the Linnéan Society, in which, like the present system, he opposes Mr. Knight's hypothesis of gravitation as the cause of the peculiar stimulus and action of plants, and conceives that "the direction of the plumale and radicle of plants must be resolved into vegetable instinct, precisely analogous, and equally inexplicable with animal instinct."-See Thomson's Ann. of Philos. vol. iii. p. 71. or No. 19.

actions are the actions of the living principle; and either is that power which characteristically distinguishes organized from unorganized matter, and pervades and regulates the former as gravitation pervades and regulates the latter, uniformly operating by definite means, in definite circumstances, to the general welfare of the individual system or of its separate organs; advancing them to perfection, preserving them in it, or laying a foundation for their reproduction, as the nature of the case may require. It applies equally to plants and to animals, and to every part of the plant as well as to every part of the animal, so long as such part continues alive.* It is this which maintains from age to age, with so much nicety and precision, the distinctive characters of different kinds and species; which, as is noticed in a preceding study, carries off the waste or worn out matter, supplies it with new,† and in a thousand instances suggests the mode of cure, or even effects the cure itself, in cases of injury or disease. It is "the divinity that stirs within us" of Stahl; the vis medicatrix naturæ of Hoffman and Cullen, and the physicians of our own day. It is hence the strawberry travels from spot to spot, and the cod or the cuckoo, with a wider range, from shore to shore, or from climate to climate.§

In supplying the place of reason, it is perpetually assuming its semblance. Let us take an example or two from both the vegetable and the animal world.

In order that the seeds of plants should produce and perfect their respective kinds, it is necessary that their shoots should rise to the surface of the earth to enjoy the benefit of light and air. Now in whatever direction the eye of a seed, from which germination first radiates, is placed, these shoots ascend equally to the surface, either in curved or straight lines, according as such ascent may be most easily accomplished. Mr. John Hunter sowed a quantity of peas and beans with their eyes placed in different directions, in a tub, which he afterwards inverted, so that the bottom was turned uppermost, while the mould was prevented from falling out by a fine net. And in order that the under surface might possess a superior stimulus of light and heat to the upper, he placed looking glasses around the mouth of the tub in such a way that a much stronger light was reflected upon the inverted mould than that of the direct rays of the sun; while at the same time, he covered the bottom of the tub with straw and mats to prevent the mould, in this direction, from being affected by solar influence. Yet the same instinctive law of ascent still prevailed. After waiting a considerable length of time, and perceiving that no shoots had protruded through the lower surface of the mould, he examined the contents of the tub, and found that they had all equally pressed upwards and were making their way through the long column of mould above them,

Mr. Knight, while he seems desirous of resolving the principle of vegetable action into centripetal force, has shown that the sap of plants, as it exists in the leaves of potatoes and mint, and the leaves and shoots of the vine, possess what he calls organizable matter; and when plunged in a moist and warm soil will produce bulbs or roots more or less perfect, or at least preserve and endeavour to extend life.-Phil Trans. 1816, p. 289. The whole, like the reproduction of polypes and worms from sections, ought rather to be resolved into the common law of instinct, the aim of which is health, preservation, or reproduction; and hence the sap of plants seems as much alive as the blood of animals. † Ser. I. Lect. XIV.

First lines, vol. i. p. 91. 105.

In conformity with the general principles of his system, Dr. Darwin ascribes this extraordinary faculty also to the power of reason. "It is probable," says he, "that emigrations were at first undertaken as accident directed, by the more adventurous of their species, and learned from one another like the discoveries of mankind in navigation."-Zoon. sect.

xvi. 12.

towards the reversed bottom of the vessel; and that where the eyes had been placed downwards, the young shoots had turned round so as to take the same direction. As one experiment leads on to another, he determined to try the effect of placing other seeds of the same kinds in a tub, to which a rotatory motion should be given, so that every part of it might be equally and alternately uppermost, and the seeds should have no advantage in one direction over another. Here, as we often behold in other cases, the instinctive principle of accommodation was baffled by a superior power, and the different shoots, instead of ever turning round, uniformly adhered to a straight line, except where they met with a pebble or any other resistance, when they made a curve to avoid such obstruction, and then resumed a straight line in the direction into which they were thereby thrown, without ever endeavouring to return to the original path.

Among animals we have various proofs of a like impulse, and we have also proofs of its being occasionally overpowered by a stronger cause. Thus, in cases of eruptive fever, there is an obvious effort of the instinctive principle to throw the morbific matter towards the surface of the body, where it can do least mischief. And where a deep-seated abscess has formed in the immediate neighbourhood of a cavity that cannot be opened into without great danger, as that of the chest or the stomach, the same instinctive principle of preservation leads forward the action in a different direction, though, as in the experiment of the bean-seeds in the inverted tub, with much greater labour and difficulty; and the abscess at length opens externally; and the remedial process of the formation of new living matter which immediately succeeds, commences under the same mysterious guidance. If, in the course of this common tendency to the surface, an obstructive cause be encountered, of superior force to the instinctive principle itself, the latter, as in the experiment of the beans exposed to the action of a rotatory motion, is overpowered, and the result is doubtful, and often fatal.

But these examples are general: let us advert to a few of a more particular nature. All the different species of birds, in constructing their nests, not only adhere to a peculiar plan, but, wherever they can obtain them, to peculiar kinds of materials; but if these materials be not to be procured, the accommodating power of the instinctive principle, as in the cases just related, directs them to others and suggests the best substitutes. Thus the red-breast uniformly prefers oak leaves as a lining for her nest, wherever she can acquire them; but if these be not to be had, she sup plies the want by moss and hair. So where the bird is of small size, and the eggs are naturally numerous, the nest is always made proportionably warm, that the nestlings may all equally partake of the vivifying heat. Thus the wren, who lays from ten to eighteen eggs, constructs her little edifice with the greatest care and of the warmest materials; while the plover and the eagle, whose eggs are so few that the body may easily cover them, build with little solicitude, and sometimes content themselves with the naked cleft of a rock. And thus too, in very cold winters in Lapland, the fond waterfowl will occasionally strip the down off its breast to line its nest and protect its progeny.

When a wasp, in attempting to transport a dead companion from the nest, finds the load too heavy, he cuts of its head, and carries it out in two portions.*

"Smellie, vol. ii. 151. Reaumur, tom. xi. 241. For an aecount of other curious instances

A strawberry offset planted in a patch of sand will send forth almost the whole of its runners in the direction in which the proper soil lies nearest, and few, and sometimes none, in the line in which it lies most

remote.

"When a tree which requires much moisture (says Mr. Knight,) has sprung up or been planted in a dry soil, in the vicinity of water, it has been observed that much the larger portion of its roots has been directed towards the water; and that when a tree of a different species, and which requires a dry soil, has been placed in a similar situation, it has appeared in the direction given to its roots, to have avoided the water and moist soil."*

"When a tree (remarks Dr. Smith) happens to grow from seed on a wall, (and he particularly alludes to an ash in which the fact actually occurred,) it has been observed, on arriving at a certain size, to stop for a while and send down a root to the ground. As soon as this root was established in the soil, the tree continued increasing to a large magnitude."t

The best means, perhaps, that a plant can possess of resisting the effects of drought, is a tuberous or bulbous root. The grass called phleum pratense, or common catstail, when growing in pastures that are uniformly moist, has a fibrous root, for it is locally supplied with a sufficiency of water; but in dry situations, or such as are only occasionally wet, its root acquires a bulbous form, and thus instinctively accommodates the plant with a natural reservoir. And there are various other grasses, as the alopecurus geniculatus, or geniculate foxtail, that exhibit the same curious adaptation.‡

There are some philosophers and physiologists who have endeavoured to ascribe the whole of these very extraordinary phænomena to the mechanical powers of gravitation and centrifugal force, among whom I may especially mention Mr. Knight, who has attempted it in the very ingenious paper to which I have just alluded. There are others who ascribe them to the operation of an intelligent principle, among whom, more especially, as I have already observed, is Dr. Darwin. Of these two causes the instances just submitted to you, and thousands more might be added to them, sufficiently prove that the first is inadequate, and that the second does not always exist; at least that the phænomena are often found in organized forms in which, to a certainty, the precise organs do not exist, which are the only known seats of intelligence and sensation in the visible world. They are hence to be resolved into another cause, equally remote from either, more complex in its operations than that of gravity, but less so perhaps than those of intelligence and feeling; embracing a distinct family of well-defined and cognate actions, always aiming at the same common end, the perfection, preservation, or reproduction of the system, in which they exist; and constituting what we should denominate instinct, the general property of the living principle, or the law of organized life in a state of action.

But the subject is too important to be closed here. It remains yet to point out the difference between instinct and sensation or feeling, as well

of instincts in insects, see Swedish Amanitates Academicæ, vol. iii. art. 45. Noxa Insectorum, by M. A. Bochner 1752; and compare with these the younger Huber's Recherches sur les Mœurs des Fourmis Indigenes. Introd. to Botany, p. 114.

* Phil. Trans. 1811. p. 210.

I See Smith, Introd. to Bot. p. 118. and p. 41.