Page:Popular Science Monthly Volume 26.djvu/767

Rh which so constantly exhibits dizziness, is associated with marked disorder of the cerebellum.

In coming to a conclusion respecting the function of this organ, we find that it can not be directly connected with sensation or volition. The sensations appear pronounced and the movements vigorous after destruction of the cerebellum. The marked feature in all deep cerebellar disorders is the maladjustment of muscular actions to the preservation of equilibrium and to harmonious movements. The consciousness of a normal relation between the person and the external world seems overthrown, the violent activities which ensue being plainly attempts to restore this lost feeling. Movements which are voluntarily initiated must be brought into relation with the position of the body in space. The cerebellum is the organ specially concerned with this work. The regulation of all activities that are willed depends upon this feeling of the accustomed relation between ourselves and objects. The cerebellum, in some unknown way, makes the preservation of this feeling possible.

It should be distinctly borne in mind, however, that this conclusion does not necessitate the further one that the cerebellum is itself a seat of consciousness, not even of this consciousness of normal relation. Consciousness may be entirely conditional upon the activities of the cerebrum, while at the same time this feeling of relation may depend upon the cerebellum. My meaning is that, though consciousness have its sole physical antecedent in the cerebrum, the special form of consciousness now under consideration may be impossible of origination in the cerebrum without the anatomical and physiological integrity of the cerebellum. Before examining the evidence concerning the functions of the cerebrum, a few words should be said with regard to the optic lobes or corpora quadrigemina, the corpora striata, and the optic thalami. The optic lobes are central organs connected with vision. There seems no sufficient reason to doubt the results of experiment as stated by Ferrier: "The more prominent effects of destructive lesions of the optic lobes in the various animals seem to be blindness, paralysis of irido-motor and some oculo-motor reactions, disorders of equilibrium and locomotion, and in frogs, and apparently in other animals, annihilation of certain forms of emotional expression."

If the higher brain-masses be removed, animals show reflex reactions to rays of light, and, more than this, they display other bodily movements evidently due to the influence of light. According to Longet, birds will follow a burning candle with their heads, and frogs that have been startled into movements of flight by irritation of the skin will avoid objects placed in their way.

These lobes are exceedingly sensitive to electrical stimulation, and the results vary as the electrodes are placed on the anterior (nates) or posterior (testes) eminences.

Stimulation of the nates causes wide dilatation of the opposite