EXTIRPATION OF THE CEREBELLUM 597" 



the pons. The inferior peduncles are connected with the restiforrn 

 bodies of the bulb and through the bulb with the posterior columns of 

 the cord. 



Extirpation of the Cerebellum. When its greatest part or the entire 

 cerebellum is removed from a bird or a mammal, the animal being 

 before the operation in a normal condition and no other parts being 

 injured, there are no phenomena constantly and invariably observed 

 except certain modifications of the voluntary movements (Flourens). 

 The intelligence, general and special sensibility, the involuntary move- 

 ments and the simple faculty of voluntary motion remain. The move- 

 ments, however, are irregular and incoordinate ; the animal can not 

 maintain its equilibrium ; and on account of the impossibility of making 

 regular movements, it can not feed. This want of equilibrium and of 

 the power of coordinating the muscles of the general voluntary system 

 causes the animal to assume remarkable postures, which, to one 

 accustomed to these experiments, are characteristic. Later experiments 

 on the inferior animals, as well as pathological observations on the 

 human subject, have shown that muscular coordination is disturbed 

 when the median lobe is extirpated, while removal of the lateral lobes 

 has no such effect. It is well known that many muscular acts are more 

 or less automatic, as in standing, and, to a certain extent, in walking. 

 These acts, as well as nearly all voluntary movements, require a certain 

 coordination of the muscles, and this, and this alone, is affected by 

 destruction of the middle lobe of the cerebellum. 



Pathological Observations. Records of cases of lesion of the cere- 

 bellum in the human subject have accumulated until the number is 

 quite large. A study of cases in which the phenomena referable to 

 cerebellar injury were not complicated by paralysis, coma or convulsions, 

 shows that serious lesion of the middle lobe is almost always attended 

 with marked muscular incoordination ; but cases in which only a por- 

 tion of one or of both hemispheres is involved may not present any 

 disorder in the muscular movements. These facts are in accord with 

 the results of experiments on the lower animals. 



The phenomena observed in cases of cerebellar incoordination are 

 notably different from those presented in simple locomotor ataxia. In 

 cerebellar disease, the gait is staggering, much as it'is in alcoholic intoxi- 

 cation. The chief difficulty seems to be in maintaining the equilibrium 

 in progression, even with great care and close attention on the part of 

 the patient. With the idea in mind that there is a coordinating centre 

 for the muscles of progression, and that this centre acts imperfectly, it 

 seems as though an efficient effort at coordination were impossible. In 

 locomotor ataxia, patients seem to make coordinating efforts, but the 



