philosophers. The eggs which escape these voracious fishes are hatched under the sand. Soon after, millions of minute crabs are seen leaving the shore, and migrating slowly toward the mountains. Most of the old ones, however, remain in the flat parts of the country till they regain their strength. They dig holes in the earth, the mouths of which they cover with leaves and mud. Here they throw off their old shells, remain quite naked, and almost without motion for six days, when they become so fat that they are esteemed delicious food. When the new shell has hardened, the animals, by an instinctive impulse, march back to those mountains which they had formerly deserted. In Jamaica, where they are numerous, the land-crabs are regarded as great delicacies; and they are so abundant, that the slaves are often fed entirely upon them. The migrating principle is not confined to men, quadrupeds, birds, and reptiles: it extends to many of the insect tribes. Numberless inhabitants of the air pass the first stages of their existence in the waters. There they remain for longer or shorter periods, according to the species. Previous to their transformation into chrysales, they quit the waters, and come upon dry ground, where they undergo their amazing change. Instead of active waterworms, they dig or find holes in the earth, where they are converted into chrysales, or seemingly inanimate beings, and, in a short time, mount into the air in the form of winged insects. Similar migrations are to be observed among land-insects. But migration is not confined to water-worms. Many species of caterpillars which feed upon the leaves of trees, shrubs, and other vegetables, when about to undergo their transformation, leave their former abodes, descend from the trees, and conceal themselves in the earth. The hiving of bees, when nu merous colonies remove in order to establish new settlements, is another instance of the migration of insects. Indeed, if we except bees, wasps, ants, and a few others, most insects, whether they inhabit the air, earth, or waters, are perfect wanderers, having no fixed place of residence. Some of them, as the spider tribes, build temporary apartments; but, when disturbed, they migrate to another commodious place, and erect new habitations. From the facts which have been enumerated, it is apparent, that the principle of migration, or the desire of changing situations, is not confined to particular birds, but extends through almost the whole system of animation. Men, quadrupeds, birds, fishes, reptiles, insects, all afford striking examples of the migrating principle. From the same facts it is equally apparent, that the general motives for migrating are similar in every class of animals. Food, multiplication of species, and a comfortable tempera ture of air, are evidently the chief causes which induce animals to remove from one place to another, or what amounts to the same thing, from one climate to another. Partial emigrations, or emigrations to small distances, are prompted by the same instinctive motives which induce animals of a different structure to undertake long and fatiguing excursions. But, previous to actual migration, what are the peculiar feelings of different animals, and what should stimulate them to proceed uniformly in the direction that ultimately leads them to the situations most accommodated to their wants and their constitutions, are mysteries, with regard to which, like every other part of the economy of Nature, it is the duty of philosophers, instead of attempting to push their inquiries beyond the bounds of human ability, to observe a respectful silence. No. LXVIII. ON THE INSTINCT OF BRUTES. Nor will it less delight th' attentive sage SOMERVILE. This trath shines bright to human sense; DYER. THE Divine Wisdom and Goodness may be still further demonstrated, not merely from the senses of animals in general, of which I have recently treated, but in the provision which he has made for the brute creation in particular, by that wonderful faculty which we call instinct; and which I would define to be a natural disposition or sagacity with which animals are endued, and by virtue of which they are enabled to provide for themselves, to know what is good for them, and are determined to propagate and preserve their species. Many of the ancient philosophers ascribed to brutes an understanding, differing only in degree from that of man, and attributed their inferiority to the want of proper and sufficient bodily organs. This system has been very strenuously supported by M. Helvetius, in his treatise De l'Esprit. Among the moderns, the learned Dr. Cudworth endeavoured to explain the instinct of animals, by means of a certain plastic nature. Des Cartes thought that all the actions of brute animals might be explained by the simple laws of mechanism. He considered them as machines totally devoid of life and sentiment, but so curiously constructed by the Creator, that the mere impressions of light, sound, and other external agents, on their organs, produced a series of motions on them, and caused them to execute those various operations, which had before been ascribed to a certain principle of life and spontaneity. But the actions and manners of animals, which are totally incompatible with the mere principles and laws of mechanism, evince the absurdity of this opinion. The celebrated Buffon, however, adopts it in part; but he allows them life, and the faculty of distinguishing between pleasure and pain, together with a strong inclination to the former, and aversion from the latter. By these inclinations and aversions, he undertakes to account for all, even the most striking operations of animals; affirming that, in consequence of impressions made on the brain, by means of the sensitive organs, and by the reaction of the brain and nerves on the muscles, these machines acquire a motion conformable to the nature of the animal, and of the impressions of the different objects which act upon their organs, and excite desire or aversion, The pre-established harmony of Leibnitz has also been applied to explain the actions of brute animals. Others have considered their actions as produced by the constant and immediate influence of the Divine Energy, directing all their inclinations and motions: such appears to have been the opinion of Mr. Addison. The Abbé de Condillac, in his Essay on the There is not, in my opinion, any thing more mysterious in nature than this instinct in animals, which thus rises above reason, and falls infinitely short of it. It cannot be accounted for by any properties in matter, and, at the same time, it works after so odd a manner, that we cannot think it the faculty of an intellectual being. For my own part, I look upon it as upon the principle of gravitation in bodies, which is not to be explained by any known qualities inherent in the bodies themselves, nor from any laws of mechanism, but, Origin of Human Knowledge, after giving his opinion that brutes have no memory, defines instinct to be-imagination re-exciting, upon the presence of an object, such perceptions as are connected with it, and thereby directing every species of animals, without the assistance of reflection. But all the varieties of opinion on this subject have been accurately enumerated by M. Reimar, in his Observations Physiques, published in 1770. This ingenious philosopher, after defining instinct, in the most comprehensive sense of the word, to be every natural inclination, accompanied with a power, in animals, to perform certain actions, divides instincts into three heads. The first, which he calls mechanical instincts, belong to the body, considered as an organized substance, and are exercised blindly and independently of the will of the animal. Such are those which produce the motion of the heart and lungs, the contraction and dilatation of the pupil, digestion, &c. This class of instincts is possessed in common both by men and brutes, and, in some measure, even by vegetables. The second class comprehends those which he terms representative, instincts, which consist partly in the power to perceive external objects by their present impression on the senses, and partly by the facility of rendering the ideas of these objects present to the mind by the powers of imagination, or of memory, in a lax sense of the word. These are common to men and other animals, excepting that brutes possess the faculty of imagination only in common with us, and not that of memory, in the strict and proper sense of the word. Indeed, M. Reimar endeavours to prove that the knowledge of brutes does not merely differ according to the best notions of the greatest philosophers, is an immediate impression from the First Mover, and the divine energy acting in the creatures.' |