A STUDY OF THE SUPERIOR OLIVE. 



107 



this nucleus. There is also, of course, a similarity in the gross morphological 

 features of the nuclear masses as well, but the conformity to type of the gross 

 outline is neither so striking nor so significant as is the likeness of the cells charac- 

 teristic of this nucleus. These features were noted throughout the series of animals 

 used in that study. The same morphologic similarity obtains in the case of the 

 superior olivary nucleus, both for the mass of the nucleus and more particularly 

 for its constituent cells. It will be found that when complete adult differentiation 

 has been attained these two groups of cells those of the inferior and those of the 

 superior olive will each have developed into a type of cell peculiar to and charac- 

 teristic of the given collection or nuclear mass within which it is found, each ty pi- 

 being sufficiently definite as to morphology to enable the investigator to positively 

 determine its proper repository without difficulty, as shown in figure 1, a camera- 

 lucida tracing of the various cells under discussion. (Compare these with the 

 microphotographs of the different sections, figs. 4, 5, and 6, plate 1). 



A B c D 



TEXT-FIGDRB 1. Outline tracings of the cells in the two olives: cells A-E inclusive are from the human inferior olive; 

 cells F-I are typical cells from the superior olive of an adult clog; cells J-M are from the medial mass of the 

 superior olive of an adult cat; cells N-P are from the lateral mass of the same; cells Q-U are typical cells from 

 the superior olive of a human fetus. The outlines were made with camera lucida, A-P being made with a 

 4 mm. objective and No. X ocular, Q-LI being made with a 1/12 objective and No. X ocular. 



The cell type which is characteristic of the superior olive is more or less 

 definitely spindle-shaped, a great number being true spindles with a narrow, long- 

 drawn-out cell body, the nucleus being compressed laterally (ovoid) to conform 

 to the shape of the cell body, and the processes coming off from the two extremities 

 of the spindle. Another type of cell, especially abundant in the olive of the adult 

 cat, presents a large cell body with a large vesicular nucleus, the cell body tapering 

 sharply at its two poles. Unless studied carefully through a series of sections, 

 these cells may be thought to be club-shaped. Indeed, Kolliker classes them as 

 such. A careful serial study, however, shows them to present two sharp poles with 

 a rather fat intervening body, a modified spindle. A third type of cell found in 

 but not limited to the superior olivary nucleus in all animals is a small, rounded, 



