210 Dr. E. L. Mellus. Experimental Degenerations [June 13, 



rhythmical movement of mastication. In the other experiment the 

 portion of cortex removed was in the level of the inferior genu of the 

 fissure of Rolando, between the fissure of Rolando and the precentral 

 sulcus, and the movement obtained on stimulation was elevation of the 

 opposite angle of the mouth. None of the brains in this group were 

 examined above the level of the inferior genu of the fissure of Rolando. 

 In three cases, one of lesion of the mastication centre and two of lesion 

 of the centre for opening the mouth, only fine degeneration resulted 

 from the lesion ; in the other four both coarse and fine. In two 

 cases of " opening mouth " and in the lesion posterior to the plane of 

 the fissure of Rolando, coarse degenerate association fibres were only 

 found in the upper levels of the lesion or above, where they were mixed 

 with more or less fine, the proportion of coarse to fine increasing from 

 the lesion upward, while the aggregate amount of degeneration 

 decreased. In all the lesions on the border of the fissure of Sylvius 

 anterior to the fissure of Rolando, most of the degeneration was found 

 in the ascending frontal convolution from the border of the fissure of 

 Sylvius to the level of the inferior genu of the fissure of Rolando. 

 In the lesion of the mastication centre all the degeneration was very 

 fine, and in the left hemisphere, with the exception of a few fibres 

 near the base in the ascending parietal, the .degenerate association 

 fibres were confined to the ascending frontal convolution. In the 

 four lesions of the centre for opening the mouth degenerate associa- 

 tion fibres were also distributed to the ascending parietal, the 

 posterior half of the inferior frontal, and the posterior or upper 

 extremity of the superior temporal convolutions. In only one of 

 these four cases was any degeneration found in the inferior temporal 

 convolution. In the lesion posterior to the plane of the fissure of 

 Rolando both coarse and fine degeneration was distributed to the 

 central convolutions, the fine degeneration above the lesion being 

 mixed (as noted above) with coarse fibres, which were more 

 numerous in the ascending parietal convolution. No degeneration 

 was traced into the frontal convolutions in this case, but a good deal 

 of coarse degeneration passed from, the superior temporal convolution 

 to the posterior extremity of the internal capsule, where it turned 

 downward and forward in the posterior limb. A mingling of this 

 with the degeneration in the internal capsule coming from the lesion 

 could not be demonstrated. In the case of the lesion on the upper 

 border of the facial area the coarse degenerated association fibres are 

 almost entirely confined to the neighbourhood of the lesion. In 

 addition to this, fine degeneration is distributed to the central convo- 

 lutions nearly to the fissure of Sylvius. The degeneration in the 

 supra-marginal gyrus and in the inferior frontal convolution is much 

 more than in any other experiment, the degeneration in the latter 

 convolution reaching to the anterior extremity of the precentral 



