THE CEREBELLUM, AND ITS FUNCTIONS. 677 



fact having been confirmed by other experimenters ; but it is a phenomenon 

 of such rarity, that it cannot be rightly considered as having any direct de- 

 pendence upon the injury of the Cerebellum, but must be rather set down 

 to some accidental complication or concurrent disturbance; more especially 

 since, as already pointed out ( 545), the function attributed by Magendie 

 to the Corpora Striata has no real existence. But the results of section of 

 one of the Crura Cerebelli, which were first obtained by Magendie, are much 

 more constant; for the performance of this operation causes the animal to 

 fall over upon one side, and to continue rolling upon its longitudinal t/.nx, 

 even as fast (in some instances) as sixty times in a minute, the movement 

 going on for many days without intermission. There is a remarkable differ- 

 ence in the statements of different experimenters, however, as regards the 

 direction of this rolling movement; for whilst Magendie and Mu'ller affirm 

 that it takes place towards the injured side, Louget and Lafargue assert that 

 it takes place from the injured side towards the opposite side. This dis- 

 crepancy appears, from the experiments of Schiff, 1 to be due to a difference 

 in the locality of the section ; for he states that if the peduncle be divided 

 from behind, the animal turns towards the side on which the section is made; 

 whilst if the section be made in front, the animal turns from that side towards 

 the opposite one. This difference is explained by Longet, by the difference 

 in the course of the anterior and posterior fibres of the peduncles : for accord- 

 ing to him, the former communicate with the decussating, and the latter with 

 the non-decussating portion of the motor tract; so that, when the former are 

 injured, the animal loses control over the muscles of the opposite side, and 

 when the latter, over the muscles of the same side. This rolling movement 

 is attributed by some to the continued activity of the muscles on one side, 

 now unbalanced by that of the muscles on the other ; but if such were the 

 case, as Louget justly remarks, it ought to occur more frequently than it 

 does in cases of ordinary hemiplegia ; and, according to that experimenter, 

 observation shows that it rather depends on. a, twisting movement of the 

 spinal column, especially affecting its anterior portion, and dragging the 

 posterior (as it were) after it. 2 Thus M. Brown-Sequard, 3 who has shown 

 that similar rolling movements may be produced by lesions of other pa its of 

 the nervous centres, as the Spinal Cord, Medulla Oblougata, and Pous, ob- 

 serves that the movements do not resemble those effected by voluntary 

 muscles; but that, in consequence of the tonic contraction into which some 

 muscles are thrown, the trunk and neck of the animal are twisted as far as 

 the bones will permit, into the form of a corkscrew. He attributes the phe- 

 nomena in question, which the animal evidently endeavors to check, to the 

 irritation of a peculiar set of nerve-fibres not usually employed by the will, 

 the division of which does not cause paralysis, though they may serve as the 

 conductors of powerful motor impulses to special groups of muscles. MM. 

 Leven and Ollivier, operating on guinea-pigs, found that pricking the Cere- 

 bellum produced well-marked movements of rotation, usually proceeding 

 from the side injured towards the opposite side. They did not observe any 

 disorders of the alimentary canal similar to those noticed by Wagner and 

 others, after ablation of portions of the Cerebellum. Hitzig 4 found that by 

 electrical stimulation of the lobes of the vermiform process, he was able to 

 cause the eyes to turn to the right or left, or one upwards and the other 

 downwards. 



550. The information supplied by Pathological phenomena, when inter- 



1 De vi motoria, baseos enceph;ili inquisitions experimentales, Bockenhemii, 1845. 



2 See his Traite de Physiolosrie, torn, ii, p. 408, 1860. 



3 Central Nervous System, I860, p. 193. 



4 Untersuchungen Qber das Gehirn., 1874. 



