290 SPECIAL PHYSIOLOGY. 



ium ; and, in cases of gradual softening of this organ, the intellect 

 may remain unimpaired, even though it be almost entirely destroyed. 

 Chronic disease of the cerebellum, however, is sometimes accompanied 

 by unsteadiness in walking, without any symptoms of paralysis ; in 

 a few cases of disease of both hemispheres of this organ, backward 

 movements have been noticed, and affections of one peduncle have 

 been accompanied, in a few instances, by rotatory movements towards 

 the diseased side. 



Our general knowledge of the functions of the cerebellum being so 

 scanty, it will be no matter of surprise that we are entirely ignorant 

 of the relative importance and office of its several parts, viz., of the 

 hemispheres with their lobes, the upper and lower vermiform processes, 

 and the plicated sacs of gray matter in its interior, known as the cor- 

 pora dentata. 



The direct connection of the cerebellum with the cerebrum, is 

 limited to the small superior peduncles, whilst it is much more exten- 

 sively connected with the lateral columns of the spinal cord, by its 

 large inferior peduncles; hence its anatomical connections seem to 

 favor the views concerning its influence in the regulation and co-or- 

 dination of the muscular movements, rather than the supposition that 

 it can exercise any important mental functions. Finally, it has been 

 remarked that the gradually increased development of the cerebellum 

 in the series of vertebrate creatures, from the fish up to man, coin- 

 cides generally, with a greater and greater degree of complexity in the 

 movements which they can perform, involving sometimes almost all the 

 muscles of the body, and necessitating more extensive and perfect co- 

 ordinating power. In what way this supposed faculty is exercised, is 

 unknown. On the supposition that it co-ordinates the muscular move- 

 ments, by being the seat of the muscular sense, some have suggested, 

 that the impressions originating in the muscles, reach it through the 

 restiform bodies, which are highly sensitive ; moreover, it has been 

 surmised, that the corpora dentata are the seat of this muscular sense, 

 and that the hemispheres react upon impressions conveyed to them 

 from those bodies. Yet it is difficult to suppose that the muscular 

 sense, which appears to be only a modification of common sensation, 

 has a special ganglionic centre. It has also been suggested, that the 

 corpora dentata may be the seat of the muscular sense, and the hemi- 

 spheres, of philoprogenitiveness. (Dunn.) It must be confessed that 

 the functions of this organ are but imperfectly ascertained. 



Functions of the Cerebrum. 



The investigation of the special functions of this important part of 

 the encephalon, is surrounded by great difficulties. We have already 

 spoken of the large masses of gray matter situated deeply within the 

 cerebrum, viz., the corpora striata and optic thalami, and the part 

 they are supposed to play in the functions of sensation, and in the 

 government of motion. But, in the superficial gray matter of the 

 cerebral hemispheres, we recognize the anatomical organ which is 

 physiologically concerned in the exercise of the faculties of conscious 



