Of vertebrated animals, moreover, it is a distinguishing character that the separation of the brain from its branches, the nerves, causes death.

In annulates, the nerves are nowhere concentrated into a mass analogous to the brain of man, but are gathered up into knotted strings, two principal series of which pass longitu- dinally throughout the body, extending their branches into all the limbs.

The head, in such a formation, is therefore no longer the seat of life, or essential to life, but every segment and every limb is possessed of, and retains, vitality in equal proportion.

This diffused brain, like the concentrated human brain, appears to be the organ governing sensation, and, like that, also, seems, in its principal masses, without sensation in its own self; and its radiations do not, except as organs of the senses, generally, as in vertebrates, find their way to the surface.

From these circumstances it may be conjectured, that, had we the means of ascertaining, we should find that annulates are altogether without that acute sense of pain which we possess.