718 NERVOUS SYSTEM. 



upon the ideas concerning the functions of the cerebellum with which they are regarded. 

 We should certainly consider those cases in which disordered movements have been 

 noted, as very strong evidence, taken in connection with the results of experiments upon 

 living animals, that the cerebellum regulates equilibration and muscular coordination. 

 Some physiologists regard them as in accordance with the view that injury of the cere- 

 bellum does not affect coordination, but simply produces vertigo. It remains for the 

 reader to judge whether or not the phenomena observed in these cases indicate want of 

 coordinating power. In the case reported by Bouvier, the lesion of the cerebellum was 

 not sufficient to necessarily disturb coordination. 



We now come to the main question, whether or not, in view of the results of experi- 

 ments upon animals and the phenomena observed in cases of disease or injury of the cere- 

 bellum, this nerve-centre presides over coordination of action of the muscles, which is 

 certainly necessary to equilibration, except the muscles of the face and those concerned 

 in speech. This question, it seems to us, can be definitely answered. 



Every carefully-observed case that we have been able to find, in which there was 

 uncomplicated disease or injury of the cerebellum, provided the disease or injury involved 

 more than half of the organ, presented great disorder in the general movements, par- 

 ticularly those of progression. We have collected the more or less complete reports of 

 twelve cases. In Case II., there was softening of one-half of one hemisphere, with 

 remarkable convulsive movements. In Case V., the one so often quoted from Oombette, 

 the gait was uncertain, with frequent falling ; there was incomplete paralysis ; but, in 

 addition to the absence of the cerebellum, there was no pons Varolii. In Case VI., 

 there was no disturbance of movement, and there was partial degeneration of one lateral 

 lobe of the cerebellum. In Case VII., there was no disturbance of movement, and dis- 

 organization of one lateral lobe of the cerebellum. In Case XI., there was slight loss of 

 substance in one lateral lobe of the cerebellum, and slight " vacillation " in the move- 

 ments. In Case XII., there was an abscess involving two-thirds of one lateral lobe, and the 

 movements of the limbs were preserved. In Cases I., III., IV., VIII., IX., X., six out of 

 twelve, there was difficulty in muscular coordination, which was invariably in direct ratio 

 to the amount of cerebellar substance involved in the disease or injury. We do not make 

 the reservation, that more than half of the cerebellum must be destroyed in order neces- 

 sarily to produce difficulty in muscular coordination, upon purely theoretical grounds, but 

 we regard this point as positively demonstrated by experiments upon animals. These ex- 

 periments show that one-half of the organ is capable of performing the function of the 

 whole. We have an analogy to this in the action of the kidneys, one of which is sufficient 

 for the elimination of the effete constituents of the urine, after the other has been removed. 



Notwithstanding the contrary views of many physiological writers, we are firmly 

 convinced, from experiments and a careful study of pathological facts, that there is no 

 one point in the physiology of the nerve-centres more definitely settled than that the 

 cerebellum presides over equilibration and the coordination of the muscular movements, 

 particularly those of progression. In this statement, we make exceptions in favor of the 

 movements of respiration, deglutition, of the face, and of those concerned in speech, as 

 well as the involuntary movements generally. As another example of a nerve-centre pre- 

 siding over muscular coordination, we have the instance of the portion of the left anterior 

 lobe of the cerebrum which coordinates the action of the muscles concerned in speech. 



The theory that the disordered movements which follow injury of the cerebellum are 

 due simply to vertigo is not tenable ; and in only one of the cases cited is vertigo men- 

 tioned. There is a disease, involving the semicircular canals and other parts of the inter- 

 nal ear, called M6niere's disease, in which there is marked want of equilibration and 

 muscular coordination, attended with, and probably dependent upon vertigo. The ver- 

 tigo is always very distinct and is mentioned in all of these cases ; and, although it is less 

 in the recumbent posture, it is never entirely absent. A careful study of these cases, 

 comparing them with the cases of deficient coordination from disease of the cerebellum, 



