154 PHILOSOPHY OF ZOOLOGY. 
For the confirmation or refutation of these opinions, va- 
rious methods have been employed, by physiologists and 
anatomists, 
The dissections of the brain have, to a certain extent, 
pointed out its structure, and some of the modifications 
which it exhibits ; but there are few who will venture to as- 
sert, that the peculiar functions of the nervous system of 
any animal may be determined, by the appearances exhibit- 
ed by the brain. How vastly superior are the intellectual 
powers of man to the monkey ; yet the brains of both bear 
the closest resemblance to each other. By comparing the 
brain as it appears in the different classes of animals, 
we certainly witness very remarkable modifications of form. 
As we descend towards fishes, the cerebrum diminishes 
so much in size, that its total absence may be inferred in 
the lower classes. Observation confirms the supposition. 
It can scarcely be detected in the mollusca, and it is want- 
ing in the annulosa. Now, if the opinions with regard to 
the uses of the cerebrum and its different parts were cor- 
rect, we ought to find, in the animals which are destitute 
of the organ, a total want of the functions which it is des- 
tined to perform ; (for we can scarcely suppose, that any of 
the other organs of the body can supply its place). But 
still we find, among insects, for example, not merely sensa- 
tion and volition, but instincts, propensities, and delibera- 
tion, which, when they occur in the higher classes, are con- 
sidered worthy of having peculiar organs set apart for their 
production. But the cerebellum still exists in these mol- 
lusca and annulosa; and may, therefore, be considered as 
exercising the functions of sensation and volition. Let us 
descend, therefore, to the inhabitants of the Corals or to 
the Hydree ; in these, neither brain nor nerves can be per- 
ceived. Yet they evidently possess both sensation and vo- 
lition, and as evidently want a cerebrum and cerebellum. 
