1 ། ON INSTINCT. 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 Of its cause and nature we know ( with much propriety, the PRINCIPle of life. 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.* The law of instinct, then, is the law of the living principle: instinctive 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 lat ter, 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. * This Lecture was delivered January, 1813; and Mr. Keith on Tuesday, December 7, 1813, had a valuable paper read before the Linnæan 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 plumule and radicle of plants must be resolved into vegetable instinct, precisely analogous, and equally inexplicable with animal instinct."-See Thompson's Ann. of Philos. vol. iii. p. 71, or No. 13. ↑ 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, possesses what he calls organizable matter: and when plunged in a moist and warm Boil 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 worns from sections, ought rather to be resolved into the common law of instinct, the aim of which is health, preservation, or repro duction: and hence the sap of plants seems as much alive as the blood of animals. # Series 1. Lecture 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 acci dent directed, by the more adventurous of their species, and learned from one another like the discoveries of mankind in navigation."-Zoon. sect. xvi, 12 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 pease and beans with their eyes placed in different directions, in a tub, which he afterward 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, 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 direc tion. 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 redbreast uniformly prefers oak-leaves as a lining for her nest, wherever she can acquire them; but if these be not to be had, she supplies 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 proportionally warm, that the nestlings may all equally partake of the vivifying heat. Thus the wren, who lays from ten I to eighteen eggs, constructs her little edifice with the greatest care, and t 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 water-fowl 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 off its head, and carries it out in two portions. 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 a much 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."‡ 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 phenomena to the mechanical powers of gravitation and centrifugal force: among whom I may especially mention Mr. Knight, who has attempted it in a 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 phenomena 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 as between instinct and reason. It remains yet for me to show you that all these are equally distinct principles; that they may exist separately or conjointly; * Smellie, vol. ii. 151. Reaumur, tom. xi. 241. For an account of other curious instances of instincts, in Insects, see the Swedish Amonitates Academicæ, vol. iii. art. 45. Noxa Insectorum, by M. A. Bochner 1752; and compare with these the younger Hüber's Recherches sur les Mœurs des Fourmis Indigenes † Phil Trans. 1811, p. 210. Introd. to Botany, p. 114 See Smith, Introd. to Fot. p. 113, and p. 41. and it remains also for me to offer examples from among the more curious or striking instances of each of these recondite powers, both under a more simple and a more complicated modification. This shall form the basis of our ensuing study. At present I shall only farther observe that instinct may be defined the operation of the principle of organized life by the exercise of certain natural powers directed to the present or future good of the individual; and reason the operation of the principle of intellectual life, by the exercise of certain acquired powers directed to the same end. Both equally answer their object, are equally perfect in their kind, and equally display their common origin. Whether with Reason or with Instinct blest, Thus all enjoy the power which suits them best; And find the means proportion'd to their end. Cares pot for service, or but serves when press'd; LECTURE V. ON THE DISTINCTIVE CHARACTERS OF INSTINCT, SENSATION, AND INTELLIGENCE. WE closed our last study by observing that instinct is the operation of the principle of organized life by the exercise of certain natural powers directed to the present or future good of the individual, while reason is the operation of the principle of intellectual life by the exercise of certain ac quired powers directed to the same end. Hence reason demands discipline and attains maturity; instinct, on the contrary, neither demands the one nor is capable of attaining the other; it is disciplined and mature from the first, and is as perfect in the infant as in the man. Instinct, however, has as often been confounded with FEELING OF SENSATION as it has with PERCEPTION, which is the outline or foundation of reason: and hence another source of those perplexities and errors in distinguishing between animal and vegetable life which we noticed in the preceding lecture: perplexities and errors which have been productive of the most absurd and disgusting consequences, and especially in regard to the delicate and elegant science of botany. Instinct, sensation, and perception are all principles essentially different; they may, indeed, exist conjointly, but each of them is capable of existing separately. Instinct is the common law or property of organized matter, as gravitation is of unorganized; and the former bears the same analogy to sensation and perception as the latter does to crystallization and chemical affinity. Instinct is the general faculty of the organized mass, as gravitation is of the unorganized mass; sensation and perception are peculiar powers or faculties appertaining to the first, as crystallization and affinity are appertaining to the second: they can only exist under certain circumstances of the organized or unorganized matter to which they respectively belong. This parallel, indeed, may be carried much farther. Gravitation discovers itself under different modifications, different degrees of power, and, conse quently, different effects. Instinct evinces an equal diversity in all these instances. Gravitation belongs equally to the smallest and to the largest portions of unorganized matter: instinct, in like manner, belongs equally to the smallest and to the largest portions of organized matter; it exists alike in solids and in fluids; in the whole frame and in every part of the frame; in every organ, and in every part of every organ, so long as the principle of life continues. Sir Isaac Newton established the doctrine of gravitation, and overcame all objections to it chiefly by the modesty with which he propounded and illustrated it. Without inquiring into the nature of its essence, he contented himself with recognising it by its operations and laws. It is the aim of the present study to follow this great example; and leaving all discussions concerning the essence of instinct or of organized life, on which instinet is dependent, and which constitutes its sphere, as matter constitutes the sphere of gravitation, to point out nothing more than the nature of its action, and occasionally to catch a glance at the laws by which it is regulated. From what has been already said, we see clearly that the power of instinct runs equally through the limits of vegetable and animal life, and consequently, that instinct, sensation and perception, whatever they consist in, are powers or principles essentially different. Instinct is the common property of organized life in all its forms, but life itself is not necessarily connected either with reason or sensation; and it is of no small consequence that we attend to this curious and extraordinary fact, the proofs of which are abundantly in our own possession. The blood is alive, and has all the common properties of life, as was very satisfactorily shown in an antecedent lecture, from the experiments of Mr. John Hunter; but we all know that it possesses neither feeling nor intelligence: the bones, the cartilages, the cellular membrane, and the cuticle are alive; but, in a state of health, they are equally destitute of both these properties, and whether in health or disease, are always destitute of the latter. Sensation and perception, so far as we are capable of witnessing, can only exist in appropriate organs, as nerves, or modifications of nerves, which are the only known seat of the one, and the brain, or some modification of brain, which is the only known seat of the other. In the higher classes of animals, as mammals, birds, amphibials, and fishes, the nerves take their rise from the brain, or rather from some particular part of it. But this is not an indispensable law of life; for, in insects, we meet with nerves, but no brain; and in most zoophytic and many other tribes of worms, with neither brain nor nerves. And hence, wherever these organs or either of them are discoverable, it is consistent with right reason to infer, that the faculty also exists to which they respectively give rise. But, on the contrary, where neither of these organs exists, as in plants, and a multitude of the lowest tribes of animals, which in the zoological system of Lamarck are on this account denomi nated apathic or insentient, we have the same reason for inferring that, hough life is present, and, indeed, in many instances, peculiarly tenacious and vigorous, there is neither intelligence nor sensation; and that the whole of the vital functions and operations are performed, like the semblances of intelligence in the preceding case, by the common law of instinet; which, operating in different ways, in different organs, and beings of different struc tures, appertains to living matter of every kind. These observations will apply to the vegetable as well as to the animal kingdom; for plants have a close analogy to the senseless tribes, the tubipores, madrepores, sponges, and infusory worms, we are now contemplating their structure and origin, as well as in the limited range of their powers; these animals being in many instances equally simple in their make, and equally destitute of locomotion, and equally propagating their kinds by the generation of buds or bulbs, instead of by that of seeds or eggs. Like these low kinds of animals, plants, moreover, are altogether without organs either of sense or intelligence; and it is consequently correct to infer, that they are Philosophie Zoologique. |