266 E. VICTOR SMITH 



b. The Gasserian ganglion. The cells of this ganglion in the 

 screech owl are relatively smaller than those in the chick, and 

 are arranged in elongated groups of three to five cells through- 

 out the larger portion of the ganglion, only a narrow peripheral 

 portion of the ganglion lacks this grouping of the cells. 



The cells are more uniform in size than those of the Gasserian 

 of the chick. The major diameters vary between 20 and 40 m, 

 and the minors between 15 and 30 m- A small number of the 

 cells are rounded, a larger number are elliptical to pear-shaped. 

 Lobulated cells are characteristic and form a series from •niere 

 irregularities of outline (fig. 31) to well formed lobes (fig. 32). 



Although the cells show such variations the nuclei are decidedly 

 regular. They vary from round to elliptical, the rounded form 

 predominating. They were usually near the center, but sometimes 

 close to the cell wall. A single nucleolus was observed in each 

 nucleus. 



The processes do not follow a direct course near the cell as in 

 the Gasserian of the chick. Quite commonly they take a mean- 

 dering course (fig. 32) as also in the vagus of the same bird. 

 Occasionally, an initial glomerulus is observed (fig. 33). As in 

 the vagus ganglion, the process issues as frequently from the 

 minor axis as from the major axis of the cell. 



Accessory processes near the base of the main process (figs. 

 31, ac.pr.) were not uncommon. They were usually very fine 

 and terminated in small rounded enlargements. Sometimes, 

 also, they emerged from the main process near its place of union 

 with the cell (fig, 31, acpr.^). Few examples of fenestration 

 (fig. 31, fen.) were seen. 



Pericellular networks were observed in a few instances, being 

 similar in structure to those described in the vagus ganglion of 

 the chicken. In the Gasserian of the owl were seen, very dis- 

 tinctly, the non-medullated fibers so prominent in the Gasserian, 

 tenth, and spinal ganglia of the chick. These fibers stain black 

 and are about one-fourth the diameter of the main processes of 

 the sensory cells. A few small vacuoles were observed. 



c. Ganglion of the auditory nerve. The cells of this ganglion 

 are relatively small and bipolar, the majority of them being 



