The Excitable Cortex of the C'liimjxinzee, Oranjj-Utan, and (lorilla 185 



able with certainty. In the lumbar enlarfjenient no defjeneration can be 

 detected. 



The ventral horn of ;;rey matter in the lower part ol' the brachial en- 

 lari^ement shows, especially in 7th and Sth cervical sei^ments, a marked 

 difierence between the rii,dit and left sides. ( )n the right side, the whole 

 of the cross-area of ventral horn has scattered through it many degenerat- 

 ing fibres of very minute size ; they give a " peppered " appearance to the 

 grey matter there, in contrast to the ordinary clean appearance of the 

 corresponding grey matter of the left half of the cord. The peppering is 

 perhaps most marked in the dorsolateral and ventrolateral cell-group 



Fig. 21. — Mici-ophotogram of direct pyramidal tract degenerated, along lip of ventral fissure, 

 at 3rd cervical segment. Marchi preparation. Ablation-e.\j)eriment 1. 



regions. It is certainly least in the medio-ventral cell-group. Sections 

 stained with Marchi show these degenerated fibres in the grey matter but 

 slightly, although, w^hen aware of them, one can detect the presence of a 

 number of them by that method. The degeneration in the ventral horn is, 

 however, much better revealed by the Schafer (88) combination of the 

 Marchi and Kulschitzky methods ; the minute blue-black ring surrounding 

 the pale axis cylinder, w-hich many of the very small fibres in the grey 

 matter give by that method, when seen in cross-section, is altered to a 

 minute blob containing no axis cylinder. In other words, the fine col- 

 laterals are degenerated, and their sheaths, with that element of it which 

 the hsematoxylin stain after the mordant tinges deeply, is broken up, and 

 the axis cylinder also ; and this kind of minute degeneration is scattered 



