THE ACOUSTIC COMPLEX OF THE OPOSSUM 425 



tract remains. This group of fibers can be better traced in hori- 

 zontal sections. The region in the angle between this and the 

 spinal vestibular tract is a matted mass of fibers which cannot 

 well be represented in low power pen and ink work. Such a 

 complex well deserves Golgi analysis. A portion of these fibers 

 are undoubtedly a part of the connections of Deiter's with the 

 vestibular tracts. Another part can be shown to be aberrant 

 strands of the seventh nerve, which appears in the next few sec- 

 tions. A considerable number of them probably represent inter- 

 nal arcuates, and the connections of Deiter's with the median 

 longitudinal fasciculus. Still others are fibers to the olivo-coch- 

 lear tract. An appearance perhaps striking enough to deserve 

 mention, is found in the other half of this section. One coarse 

 strand of fibers presents every appearance of being an olive-cere- 

 bellar connection, lying somewhat lateral to the remnants of the 

 main band of olivo-cochlear fibers, and joining the nucleo-cere- 

 bellar path of the vestibular above. On going back and forth 

 through this region repeatedly comparing sides, the writer has 

 inclined to the conclusion, however, that this is merely an aberrant 

 strand of the olivo-cochlear system, whose close relation to an 

 ascending strand of the vestibular spinal tract produces the decep- 

 tive appearance. 



Fig. 7. Series A, slide 88, row 2, section 2. This section is 

 somewhat anterior to the previous one, and involves the radix N. 

 facialis. The features of special interest center around the cor- 

 pus trapezoideum and the olive and its connections. 



The region marked A in this section represents the principal 

 feature for discussion. In reviewing the descriptions of the corpus 

 trapezoideum given by Cajal, von Kolliker, Edinger and Held, 

 the writer has been unable to find any reference to a possible con- 

 nection of the corpus trapezoideum and the ventral cochlear 

 nucleus, with the cerebellar nuclei. In fact the absence of con- 

 nection of the cochlear apparatus with the cerebellum seems to be 

 emphatically pointed out by a number of writers as a main distinc- 

 tion between vestibular and cochlear systems. With this weight 

 of opinion against it, the writer calls attention to this and other 

 sections through this portion of the opossum brain with consider- 



