A STUDY OF THE SUPERIOR OLIVE. 169 



of these cells will be found grouped together, though at no place constituting 

 definite nuclear masses save such as have long since been identified and named. 

 While in every section examined some of these scattered cells were found in close 

 relation to the superior olive, in no case is it especially difficult to exclude them 

 from the make-up of the nucleus proper, since morphological^ they differ widely 

 from those proper to the olive. 



(3) There are a great number of cells in the area of transverse fibers ventral 

 to the superior olive. The difference in the disposition of the cells comprising the 

 nucleus pontis found in the lower animals as compared with man, makes their 

 study rather more difficult, and it becomes quite a problem (in the human as well 

 as in the animal forms) to separate the scattered cells into two classes, one to be 

 designated as the nucleus pontis and a second as constituting certain smaller nuclei 

 which have been described as being closely associated with the superior olive. A 

 number of these nuclear masses, such as the nucleus preolivaris, the nucleus semi- 

 lunaris, and the nucleus corpus trapezoideum, will be discussed in a subsequent 

 paper. In this connection we find, in the lower animals especially, that the great 

 majority of these cells are grouped within a rather limited area adjacent to the 

 ventral surface of the superior olive, although evidently not forming a part of this 

 nuclear complex, since these cells have, for the most part, rather large, irregularly 

 rounded, darkly staining cell-bodies with deeply staining nuclei. In this they differ 

 widely from the typical olivary cell. 



There is a quite noticeable cell group to be found at some levels, in cat tissue 

 especially, immediately ventro-mesial to the medial mass of the olive; and in one area, 

 extending over several sections, there are numerous irregular clumps of these cells 

 between the ventrally directed medial limb of the S and the ventral pole of the 

 medial mass, surrounded by streams of fibers. Thus, in a sense, they seem to piece 

 out a connection between the two portions of the major nuclear complex. These 

 groups, and others less numerous, found along the ventral surface of the olive, may 

 be genetically related to the olivary cells, though there is but the faintest mor- 

 phological resemblance. There are also many fine collaterals passing between the 

 trapezial fibers and the olivary cells proper, which stream around and among these 

 cells and possibly establish relations with them. 



Since, as has been noted above, the medial nuclear mass is well represented 

 in every animal and, conforming more closely to type, is the more constant portion 

 of the nucleus; and as the spindle cell has been seen to be the type of cell charac- 

 teristic of the superior olive, we find, as would be expected, additional support for 

 the. idea of the conformity of structure to function in the fact that the best-defined 

 and the greatest number of spindles are found in the medial nuclear mass, which 

 may therefore be assumed to be the most essential part of this nuclear complex. 



THE RELATED FIBER ELEMENT. 



There are great numbers of nerve cells in the superior olive. Associated with 

 these is a correspondingly rich network of both afferent and efferent nerve fibers. 

 These, as Cajal observed, are so numerous and so exceedingly fine and the network 



