INTRODUCTION. 
31 
stupid. They are so truly the property of the species, that all its individuals perform 
them in the same way, without any improvement. 
Thus the working bees have always constructed very ingenious edifices, agreeably to 
the rules of the highest geometry, and destined to lodge and nourish a posterity not 
even their own. The wasps and the solitary bees also form very complicated nests, in 
which to deposit their eggs. From this egg issues a grub, which has never seen its 
parent, which is ignorant of the structure of the prison in which it is confined, but 
which, once metamorphosed, constructs another precisely similar. 
In order to have a clear idea of instinct, it is necessary to admit that these animals 
have innate and perpetual images or sensations in the sensorium, which induce them to 
act as ordinary and accidental sensations commonly do. It is a sort of dream or vision 
that ever haunts them, and may be considered, in all that relates to instinct, as a 
kind of somnambulism. 
Instinct has been granted to animals as a supplement for intelligence, to concur with 
it, and with force and fecundity, to the preservation, in a proper degree, of each species. 
There is no visible mark of instinct in the conformation of the animal ; but intelli- 
gence, so far as has been observed, is in constant proportion to the relative size of the 
brain, and particularly of its hemispheres.* 
OF METHOD, AS APPLIED TO THE ANIMAL KINGDOM. 
After what we have said respecting methods in general, there remains to ascertain 
which are the most influential characters of animals, that should serve as the basis of 
their primary divisions. It is evident they should be those which are drawn from the 
animal functions ; that is to say, from tl^e sensations and movements ; for not only do 
both these make the being an animal, but they establish, in a manner, its degree of 
animality. 
Observation confirms this position, by showing that their degrees of developement 
and complication accord with those of the organs of the vegetative functions. 
The heart and the organs of the circulation form a kind of centre for the vege- 
tative functions, as the brain and trunli of the nervous system do for the animal 
* One of the most curious phenomena of instinct is the transmission 
of instilled habits by generation, as in the instance of high-bred 
pointer and setter dogs, often requiring no training to fit them for 
their particular modes of indicating game. Propensities are similarly 
hereditary in the human species ; but innate knowledge, as a substi- 
tute for individually acquired experience, is peculiar to brutes, which, 
for the most part, are thrown upon their own resources, before they 
have had time or opportunities to gain the necessary information to 
serve as a guide for the regulation of their conduct. Alt the higher ani- 
mals, except the human species, appear to recognize their natural foes 
intuitively, to know even where tlieir hidden weapons lie, also where 
they (and likewise themselves) are most vulnerable, and they endea- 
vour to use their own peculiar weapons before these are developed. If 
incapable of resistance, they commonly have recourse to stratagem ; 
thus a brood of newly-hatched partridges will instantly cower motion- 
less at sight of an object of distrust, the intent of which must be, that 
the close similarity of their colour to that of the surface should cause 
them to be overlooked. Predatory animals, again, which immolate 
victims capable of dangerous resistance, instinctively endeavour always 
to attack a vital part, so as to effect their purpose speedily, and with 
least hazard to themselves ; but those which prey on feeble and de- 
fenceless animals attack indiscriminately. Many astonishing mani- 
festations of the instinctive faculty occur respecting the manner in 
which the food is obtained ; and in the ant and some rodent quadrupeds, 
which store up grain, the embryo of every seed is destroyed, to pre- 
vent germination. 
The seasonal migrative impulse which recurs in some animals is 
among the most incomprehensible of instinctive phenomena, as it is 
shown to be, in various cases, independent of food or temperature ; 
though the latter, in particular, exercises some influence on its de- 
velopement, as does also the state of the sexual organs in spring. The 
guiding principle of migration is equally mysterious, — that which 
enables a bird of passage to return periodically to its former haunts, 
to the sarae locality (both in winter and summer), which it had pre- 
viously occupied ; and the young also to the place of their nativity. 
This principle is farther evinced in the return of pigeons, &c. to their 
accustomed place of abode from indefinite distances, and by a straightcr 
and more direct route than that by which they had been removed. It 
appears, likewise, to be manifested in somnambulism, and, perhaps, in 
some other affections of the human body; but the sexual and parental 
instincts are those which are chiefly cognizable in civilized man- 
kind. 
One curious fact connected with the migrative propensity is, that 
the same species is sometimes permanently resident in one locality, 
and migratory in another. Thus the robin, which is stationary in 
Britain, leaves Germany in the autumn ; which would seem to indi- 
cate that the erratic habit may have originated (in this instance) from 
necessity, and in course of time have become regular and transmis- 
sible, independently of external causes. Migratory animals, how- 
ever, may commonly be distinguished from others of the same genus, 
by their superior structural powers of locomotion. — E d. 
