1895.] following Unilateral Lesions of the Cortex Cerebri. 211 



sulcTis. No degeneration in this case was found in the temporal 

 lobe. In all directions the amount of degeneration decreased as the 

 distance from the lesion increased. 



The size of the degenerate fibres crossing in the corpus callosum 

 corresponded to that of the fibres proceeding from the lesion, i.e., in 

 each case in which both coarse and fine fibres were found proceeding 

 from the lesion both coarse and fine fibres crossed in the corpus 

 callosum. The coarse fibres in the corpus callosum were finer than 

 the coarse fibres elsewhere, and much less numerous than the fine 

 fibres. In all the lesions anterior to the plane of the fissure of 

 Rolando the degeneration was in the posterior two-thirds of the 

 anterior half of the corpus callosnm. Following the one lesion pos- 

 terior to the plane of the fissure of Rolando it was in the middle third, 

 thus corresponding to the hallux and thumb lesions. The convolu- 

 tions of the right hemisphere were examined in four cases, and, with 

 the exception of the case of the lesion of the mastication centre, the 

 degeneration, while corresponding to that on the left side, was rather 

 less extensive and less in amount. The majority of the degeneration 

 was in all cases distributed to the central convolutions. In the case 

 of the lesion of the mastication centre the degeneration was even 

 more extensive and of about equal amount on the right side. In 

 most of these cases but little of the degeneration passing from the 

 lesion to the left internal capsule appears in the centrum semiovale 

 as it reaches the capsule by passing over and around the anterior 

 angle of the putamen at a lower level. As much of this as reaches 

 the centrum semiovale, together with the fibres going to the corpus 

 callosum, occupies a more extensive area than in either the hallux or 

 thumb lesions, corresponding to the antero-posterior extent of both 

 central convolutions. The angle of the mouth centre was the only 

 case in which both coarse and fine fibres degenerated from the lesion 

 in which there was not marked grouping of the coarse fibres anterior 

 to the fine. 



In all the lesions of the facial area the degenerations in the upper- 

 most levels of the capsule, i.e., the coarser fibres which pass down 

 through the capsule, are situated in its anterior portion, and in the 

 lower levels move backward till they occupy in the lower levels the 

 middle third of the posterior limb. Between the upper and lower 

 levels of the capsule most of the fine degeneration passes from 

 the posterior limb into the thalamus. In the lesion of the mastica- 

 tion centre, though the degeneration in the capsule is all fine, but 

 little passes to the thalamus. In the three cases referred to in 

 which there were only fine degenerate fibres, a varying amount of 

 fine degeneration was observed in the posterior limb of the right 

 internal capsule corresponding in position to that in the left. In one 

 opening of the mouth lesion the amount on the right side was nearly 



