258 E. VICTOR SMITH 



observed. Clearly defined implantation cones (figs. 1, 4, 6) are 

 infrequent. The main process is relatively broad as it emerges 

 from the cell, but soon narrows and preserves a uniform width 

 until it branches. It usually springs from the distal pole of the 

 cell and is directed distally and also toward the central longitu- 

 dinal axis of the ganglion. The process of the unipolar cell 

 divides into two unequal branches (fig 1) at variable distances 

 from the cells, the larger branch going peripherally and the smaller 

 centrally. One process was followed for 192 /x without the divi- 

 sion having taken place. 



The few bipolar cells exhibit various transitional stages, from 

 the oppositi-polar to the unipolar (figs. 2 to 6). As in unipolar 

 cells, so in bipolar, the distally directed process is larger than the 

 proximally directed. 



A limited number of small protoplasmic slings and fenestra- 

 tions were observed in the nerve cells of the spinal ganglia (fig. 

 8, fen.,slg.). 



2. Cerebral ganglia 



a. Ganglion of the ninth nerve. The glossopharyngeal ganglion 

 of the chick is less than 0.5 mm. in diameter and diflftcult to free 

 from the connective tissue. A median, • longitudinal section of 

 this ganglion (fig. 12) shows that the cells are more numerous at 

 the center than at the periphery, and that areas of considerable 

 extent lack cells entirely. Here also, the prevailing type of cell 

 is unipolar with the processes of unequal size, the smaller being 

 directed centrally. Many non-medullated fibers occur in this 

 ganglion. In shape the cells are rounded to elliptical, the elon- 

 gated forms being the more numerous. The long axis of the nerve 

 cells is in almost all cases parallel to the long axis of the ganglion. 

 The cells are noticeably smaller in this ganglion than those in the 

 other ganglia of the same bird, their major diameters varying 

 belween 20 and 50 n, and their minor diameters between 16 and 

 33 fx. The round to elliptical nuclei are also relatively smaller 

 than in cells from other ganglia and only one nucleolus 

 was observed in any nucleus. A few bipolar cells were observed 



