412 JOHN H. STOKES 



half as wide as the corpus trapezoideum, passes rather abruptly 

 towards the roof of the Sylvian aqueduct, following the curve of 

 the outer surface of the brain stem forward, laterally, upward and 

 finally medially towards the nucleus of the inferior collie ulus, 

 whose base it enfolds '' wei ein Kelch" (von KoUiker) . The lemnis- 

 cus is deeply grooved along its medial surface, the groove broaden- 

 ing and becoming shallower as it ascends. Within this groove 

 covered by a thin layer of fibers lies the elongated cylindrical 

 ganglion mass of the nucleus of the lateral lemniscus. As the fibers 

 of the lemniscus diverge those along the dorsal margin, which con- 

 stitute the larger proportion, pass almost directly upward toward 

 the nucleus of the inferior colliculus. The more anterior and 

 ventral portion of the tract apparently ascends rather more gradu- 

 ally in the direction of the superior colliculus and the thalamus, 

 the exact destination of the fibers not being determinable from 

 the sections. A portion of them may form a direct extension of 

 the conduction path cerebralward, without interruption in the 

 inferior colliculus. The nucleus of the lateral lemniscus at its 

 lower end can hardly be said to be continuous with that of the 

 superior olive. There is a distinct gap, covering a number of 

 sections in the transverse cuts, between the point where the 

 highly characteristic structure of the superior olivary nucleus 

 entirely disappears, and the point where definite indications of a 

 lateral lemniscus, with its sharply defined nucleus appear. This 

 gap is filled with a reticulated mass containing some ganglion cells 

 apparently, which if anything, partakes of the structural appear- 

 ance of the nucleus corporis trapezoidei. There appears to be no 

 difficulty in recognizing the anatomical identity of the nucleus 

 lemnisci lateralis in the opossum at least. 



The group of fibers extending inward and downward toward 

 the median line from the upper portion of the nucleus lemnisci 

 lateralis has already been mentioned. In the separate model 

 of the cochlear apparatus (fig. 3), the same allowance should be 

 made for its conspicuousness as in the case of the olivo-cochlear 

 tract. It is less prominent in fig. 2, owing to its position along 

 the upper posterior border of the brachium conjunctivum, from 

 which, however, it appears to be fairly distinct. 



