Page:Popular Science Monthly Volume 14.djvu/495

Rh in different parts of the brain; but it is a conclusion at the same time from which Physiology simply retires in outspoken disdain, as presenting us with an empirical explanation of mysteries to which the furthest science has as yet failed to attain.

That we may duly understand, not merely the falsity of the old phrenology, but the bearings of the new aspects of brain-science as revealed by modern physiology, we must briefly glance at the general conformation of the brain. The organ of mind, contained within the skull, consists of the greater brain or cerebrum (Fig. 1, A A), and the lesser brain or cerebellum (B). The latter portion is situated at the



back of the head, and forms the hinder part of the brain; the spinal cord (C), which, as every one knows, runs through the spine (V V), being merely a continuation of the main axis of the nervous centers of which the brain is the chief. When the surface of the human brain is inspected, it is seen to present a very unequal appearance, due to the fact that its substance is thrown into a large number of folds or convolutions (see Fig. 1), as they are technically named by the anatomist. The brain, or cerebrum, is in reality a double organ, formed of two similar halves or hemispheres, which are separated by a deep central fissure, but which are also connected together below by a broad band of nervous matter known as the corpus callosum. It is this latter band which brings the halves of the brain into relation with one another, and which thus serves to produce identity and correlation of action between its various parts.