DEGENERATIONS FROM LESIONS OF TEMPORAL CORTEX. 161 



capsule, the degenerated fibres described were not the only ones 

 found in this structure. Others were scattered throughout the 

 whole of its posterior segment. A similar distribution of 

 degenerated fibres was found in the internal capsule on the side 

 opposite to the lesion. There can be little doubt, therefore, 

 that these latter crossed over in the corpus callosum, which, as 

 we have seen, contained such fibres throughout the whole of its 

 posterior half. Bilaterally degenerated fibres situated in both 

 internal capsules were also described by SIwav and myself, loc. cit., 

 after lesions of the cortex of the occipital lobe. 



On tracing these fibres downwards they were found to diminish 

 in number, and no doubt, as Hamilton'^, as well as Ferrier and 

 Turner ^ state, by the contribution of some to the optic thalami. 



Others were continued on into both peduncles, where they 

 occupied the middle regions of the crustte (see <^?. 6 and d. 7, 

 fig. 8). From here many were seen to enter the substantia 

 nigra and terminate there. Such a mode of ending of pedal fibres 

 has been observed by many investigators, and has recently been 

 confirmed by Dejerine and Lowj!^ It was also described by 

 81iaw and myself,'^ in connection with similar fibres, degenerating 

 after lesions of the occipital cortex. Muratoff^ Bothmann,^ and 

 Boyce ^ have also observed fibres leaving the pyramidal system 

 in the mesencephalon and passing towards the tegmentum. 

 The remainder of these fibres were followed in gradually 

 reducing numbers as low as the pons, beyond which they could 

 not with certainty be traced. These latter, no doubt, ended at 

 different levels in ventral grey matter on their way downwards. 

 It will be noticed that this system also furnishes bilateral 

 connections between a given cortical area and the grey matter 

 of the basal ganglia on the one hand, as well as that of ventral 

 aspect of the mesencephalon on the other. 



^ Hamilton, D. J., "On the Corpus Callosum in the Embryo," Brain, 1885, 

 p. 145 ; also " The Corpus Callosum in the adult Human Brain," Jb«ni. of Anat. 

 and Physiol., vol. xix. pp. 385-414. 



^ Ferrier and Turner, AV. A., op. cit. 



'* Dejerine, J. E., and Long, E., " Sur quelq. degener. second du tronc enceph- 

 de I'homme, etc.," Compf. Rend, de la Soc. de Biol., 30 Juillet 1898. 



■* Shaw, C, and Thompson, W. H., op. cit. 



•■* Muratotf, Arch./. Anat. il. Physiol., 1893. 



" Rothmann, Neurol. Ccntralbl., June 1896. 



"^ Boyce, o-p. cit. 



