2 Journal of Comparative Neurology. 



side* is intact except that the innermost band of fibres is filled 

 with granules to such an extent as to be decidedly darker than 

 the ectal portions. The degenerate portion does not embrace 

 more than a sixth of the whole. On the left side (that corres- 

 ponding to the injured eye) the conditions are exactly reversed. 

 The outer five-sixths is degenerate and filled with irregularly 

 disposed granules, while the ental layer appears normal or near- 

 ly so. Under a moderate power (1-5 in. obj.) the difference be- 

 tween the degenerate and normal tracts is conspicuous. The 

 unaltered portions have the nutritive granules arranged in regu- 

 lar files of 6-8 between the fibres and these rows are disposed 

 at approximately equal distances. In the degenerate portions 

 the granules are not only relatively morfc numerous but they 

 are dispersed with absolute irregularity. The fibres are no 

 longer approximately parallel but are irregularly meshed. The 

 sheaths are partly dissolved and the myelin completely ab- 

 sorbed. (Cf. Fig. II.) The tectum in this series is somewhat 

 larger on the right side but there are no demonstrable histolog- 

 ical differences. 



Passing caudad to the level of the exit of the oculo-motor, 

 we find the right root entirely absent while its fellow is normal. 

 The right nidulus of origin is also absent while the interpedun- 

 cular niduli, which some writers persist, in spite of abundant 

 evidence, in regarding as accessory third niduli, are intact on 

 both sides. It is not possible to identify positively any of the 

 elements of the missing nidulus though shrunken adendritic 

 elements occur in the site. (Fig. 3.) 



At the level where the interpeduncular nidulus ends cau- 

 dad, the cells of the fourth nidulus appear in the sections and 

 are more numerous on the right than on the left side. Still 

 there is no conspicuous difference in this subject between the 

 two sides. The dorsal longitudinal fasciculus becomes more 

 concentrated at this point and the nidulus lies directly dorsad of 

 it in a stroma of deeply staining material. There are about the 



'In discussing the sections it may be premised that the cephalic aspect of 

 the section is presented so that the right side of the section is the left side of 

 the figures. 



