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imbibes those supplies which are requisite, because its organs are solely adapted to imbibing these and no others. It avoids certain evils and attains certain advantages, by a peculiar and mysterious power of its faculties, which they possess in regard to no other objects.
The transition from plants to zoophytes is almost insensible. Many of these are fixed by roots, and multiply life in their branches, giving out deciduous buds, which again take root. The polypus possesses astonishing powers of reproduction, and displays that degree of vitality which consists in irritability to a great degree; however divided, this power remains in each part, which becomes a separate animal. These creatures may also be grafted upon one another; their powers of nutrition are confined to distinct organs; their selection of nutriment limited to certain kinds, but not much more like choice than that of vegetables.
In the order testacea, a rather higher range of vital powers are observable; the snail, for example, possesses sensibility in its tentacula; traces of nerves are found. What are called its eyes have been shewn very recently, by Sir E. Home, not to be so; its power of reproduction is great, proportioned to its irritability and small degree of nervous sensibility.
If we rise to insects, we find a much more perfect structure. They possess something like a brain, which, however, is but one of several nervous ganglia; they have no circulation; their irritability is very great; their muscular powers astonishing: but this muscular vitality is not as in the preceding classes, sufficient to reproduce lost limbs. Yet, a separated limb retains motion for a considerable time, owing to this power.
The term instinct is of very undefined meaning. We believe it is not usually applied to the impulse by which the testacea and the polypi are urged to obtain nutriment, and to propagate their species; to many of the habits of insects, it is, however, very commonly applied. As we know nothing of the ultimate principle upon which it depends, it is perhaps wrong to carry this distinction to so great an extent, as to imply any real difference between the power or principle in the two cases. It is certainly much more remarkably displayed by insects, in proportion to their more perfect organization. Their organization is such as to give them the means of performing a certain set of actions, and no others; they have also some sort of susceptibility to impulses, from whatever source, leading them constantly to that particular set of actions. Beyond this we know nothing. We may use the
term instinct to cover our ignorance, as meaning the unknown impelling power; but strictly speaking, we must not (like Dr. Hancock) attribute to it any other meaning than what is implied in the facts above adverted to; and by keeping to this very simple definition, we see that it may, without any impropriety, apply to the lower creatures also. We cannot, by any analogy, describe the origin of this power; but its continuance is closely similar to the power of habit.
That species of instinct, which impels the insect tribes to seek appropriate food, is perhaps the lowest in rank; it is displayed by those classes of insects which seem the lowest in the scale of organization: the caterpillar, for example, when shaken off the leaves of a tree, returns and crawls up the trunk, and along the branches, till it regains the situa tion best fitted for its present support and future transformation. This degree of instinct differs by only one step from that of the sea anemone. It will perhaps be admitted, that the primary impulse on the caterpillar is the sensation of hunger; but this may urge it to ascend the tree, without its employing any distinct process analogous to reasoning, to lead it from that sensation to the consideration of moving in a particular direction, and in the end finding food.
The wonderful instincts of the ant are familiarly known. The following facts, recorded by Dr. Hancock, are extremely
"The principal resource of the ant, is the honey of another insect called the aphis, an insect which abounds on the plants that are usually found in the vicinity of ant-hills. This honey is an exudation from the body of the aphis, and is absorbed greedily by the ants, without any detriment to the insect that yields it. It is voluntarily given out by the aphis, when solicited to do so by the ant. A single aphis supplies many ants with a plentiful meal. Some species of ants, we are told, bring the aphides to their own nests, instead of seeking them, when the cold is excessive, and lodge them near the vegetables on which they feed; while the domestic ants prevent them stirring out, guarding them with great care, and defending them as their own young; they even collect the eggs of the aphis, and superintend their hatching, continually moistening them with their tongue, and preserving them till the proper season for their exclusion; and in a word, bestow all the attention which they give to the eggs of their own species. The ants defend them from the ants of other societies. That they have some notions of property in these insects, would appear from their occasionally having establishments for their aphides, at a distance from the city, in fortified buildings, which they construct for this purpose alone, in places which are secure from invasion. Here the aphides are
confined as cows in a dairy, to supply the wants of the metropolis." P. 30.
We have selected this, among numerous instances of the extraordinary sagacity displayed by the ant, because it is perhaps less generally known than some others: it serves to illustrate a progressive elevation in intelligence; but it is not necessary in explaining it, to suppose that the ants act upon a distinct process of reasoning and calculation, and this observation we conceive to be of some importance towards acquiring our only definite ideas of the distinction between instinct and reason. It is clearly possible to explain these instances, without supposing a distinct putting together of separate ideas; but we will now advert to a very important instance, which, to our apprehension, carries the argument one step further, and shews that there are cases in which we cannot admit the exercise of reason, as just described; the case we allude to is that of the cells of bees, the structure of which our author has noticed briefly, and perhaps without giving his argument all the advantages it might have had. We shall not pretend to enter into the details, but shall endeavour to state those points on which the argument depends in the most simple manner. The fact then is this: it may be shewn, by mathematical investigation, that there are particular ways in which a set of contiguous cells may be constructed, so as to require less labour and materials, and to unite this saving with strength and security, in a greater degree than by any other construction; moreover, by the aid of the fluxionary method, it is possible to determine, with the utmost exactness, the precise form required, and the exact angles at which the planes terminating the figure must be inclined to each other. All this, it is important to observe, cannot be done without the application of very extended geometrical and analytical knowledge, and depends on truths which, at no very remote period, were unknown to mankind; some of them, even as late as the age of Newton. Several distinguished men have solved the problem; to give an idea of it, we may mention, that in a recent work by Dr. Cresswell, the investigation occupies 20 octavo pages.
Now, on examining the cells of the honeycomb, we find the bees have adopted precisely the figure and mode of construction which the mathematician has shewn to be the best; have selected, out of all the various forms which might have been employed, that alone in which all the advantages of economy of time, labour and materials are gained, united with greater strength and security; and not only is this rule fol
lowed nearly, but upon the most accurate measurement to which the angles can be subjected, they have been invariably found, by several observers, to be precisely those determined by calculation.
Upon considering all these circumstances, the question we would ask as this ;-is it possible to suppose that the bee proceeds to its work, upon a distinct apprehension that it is desirable to save labour and materials; upon an enquiry, whether, by adopting one particular construction, such a saving would be effected; upon a regular deduction from the first principles of geometry, up to the application of fluxionary calculation, whereby it learns that those advantages may be obtained, and what is the best construction for obtaining them? We think no one would maintain such a view of the subject; and if so, it follows that the bee must arrive at its practical directions by some shorter mode; by some other way than the process of putting together distinct ideas, till we form a connected chain of reasoning; by something analogous to an intuitive perception or feeling that the construction adopted is the right.
If then, in this case, we are sure that the animal does not proceed by regular steps of reasoning, we must by analogy extend the conclusion to the cases of other animals, such as those already spoken of.
Insects are, perhaps, the lowest class which display any accommodating power of instinct to particular circumstances; its ordinary manifestations are invariably confined to one regular routine: but sometimes the animal will shew a difference in its habits, according to a change in situation., Dr. Hancock (p. 103) illustrates this in insects by several differences observable in bees and wasps; their precautions being different according to the difference of climate.
Following the progress of organization to its higher classes, if we take the order of Amphibia, we find a structure in which irritability still predominates. Owing to this power, a tortoise has lived twenty-three days after losing its head; the jaws of a dead crocodile pulled asunder, can inflict a severe bite; and those of a viper, a mortal wound eight or ten days after death; but the nervous system begins to assume a more perfect character: the excess of vitality is not so great as to give the power of reproducing lost parts; but in proportion to the more perfect nervous organization, there is a greater degree of sensibility, and a higher range of instinct. The habits then which these classes of animals display, are of a nature approaching somewhat more to those of intelligence, and susceptible of more diversity than in
the instances hitherto considered. That most extraordinary faculty of finding their way from an amazing distance to the place they have been accustomed to inhabit, which many animals possess, has been observed in a tame serpent, as our author has related from Lord Monboddo. (P. 76.)
The remarks above made may be continued to the next class, the fishes. One remarkable instance of their instinct is the power of migration for the purpose of spawning. It is probable, that if we were not precluded from an intimate acquaintance with their habits, we should observe many other curious manifestations of instinct.
It is probably owing to their coming more within our familiar observation, that the classes of birds and quadrupeds, though decidedly superior in instinct to those below them, yet appear separated by a greater interval than perhaps is really the case.
Among birds, it will not need many instances to shew the superior degree of intuitive intelligence they possess in the regular discharge of the functions proper to their nature. Among these, there is none in which more remarkable sagacity is shewn, than in their care for their young.
The preliminary operation of building the nest, is conducted in a different manner exactly suited to its peculiar wants by each species. It is not by traditional instruction that this art is learnt, because a crow hatched by a hen, and having no communication with its species, has been observed to build with exactly the same materials, and in the same manner as the rest of its tribe. Were this faculty the result of reasoning, we should see deviations according to the peculiar wants or conveniences of each bird, as among the buildings of men. The work is perfect in its kind; we never see imperfect attempts abandoned for want of skill to complete them, or any thing like progressive improvement in the course of years or ages.
But though this faculty seems so entirely confined to one routine, yet there are cases in which instinct appears to accommodate itself to circumstances. For example,
"In countries infested with monkies, birds which in other climates build in bushes and clefts of trees, suspend their nests on slender twigs, and thus elude their enemies. The same species of birds build their nests differently, when climate and circumstances require it. Dr. Darwin has collected many facts to show, that the cuckoo in some places hatches and educates her own young; while in others she builds no nest, but uses that of some lesser bird, as the wagtail or hedge sparrow, and depositing one egg in it, takes no further care of her progeny." P. 104.