SYSTEM OF NATURE 
79 
The brain among invertebrate animals is at its lowest 
state of development: -neither confined by a bony co¬ 
vering nor centred in one locality, it becomes dissipated 
through the body, losing its excessive power of sensation, 
yet communicating an intense vitality to every part of the 
frame. The reasoning faculty which, in descending from 
man to the other Primates, then to the abnormal placen- 
tals, and then to the abnormal vertebrates, has become 
fainter and fainter, ceases altogether in the invertebrate 
tribes, and instinct, unaccompanied by reflection, reigns 
supreme. I have elsewhere said that while the concen¬ 
trated brain reflects the diffused brain acts : it impels to a 
certain course, and though destruction may possibly be 
the result it leaves no choice ; it will be obeyed. Let it 
not however be supposed that the reasoning faculty mounts 
regularly upwards from the monad to the man ; this is by 
no means the case : each group is a system in miniature, 
and its normal central form is in all probability superior to 
the abnormal forms of even a superior group. It must on 
no account be supposed that the majority of the monkeys, 
lemurs or sloths, are animals intellectually superior to the 
dog, the horse, or the squirrel, because certain osteological 
peculiarities tend to place them in the same group with 
man. The very converse of this is the fact; and much as 
we find written concerning the human character and at¬ 
tainments of the orang-otan, I should be inclined to consi¬ 
der him but little in advance of his brother apes, and some 
of these decidedly inferior to many quadrupeds which 
exhibit a much less distinct resemblance to the typical 
form of man. 
The skeleton, like the brain in the invertebrate tribes, 
loses its character, and finally ceases to exist: traces of 
