HISTOLOGY OF SENSORY GANGLIA OF BIRDS 277 



much closer together at the proximal end of the ganglion than 

 at the distal. There is but slight tendency for the cells to be 

 arranged in rows. 



The cells are smaller and more rounded at the proximal than 

 at the distal end of the ganglion. At the distal end they are 

 elongated and of relatively large size. A typical cell of average 

 size, from the central end, had for its diameters, 22 and 16 m, 

 with a nucleus whose diameters were 11 and 8 n respectively, 

 while a typical cell from the distal end was 30 m long and 16 wide 

 with a nucleus 11 by 8 m- The nuclei are relatively large, but 

 not so large as those of the ganglion cells of the ninth nerve. 



c. Gasserian ganglion. In the Gasserian ganglion of the 

 pigeon the cells extend 0.8 mm. in a direction parallel to the 

 course of the fibers, and 1.5 mm. in the direction at right angles 

 to the course of the fibers. The cells are crowded very close 

 together at the proximal end of the ganglion, and lack systematic 

 arrangement, while in the rest of the ganglion the cells are less 

 dense and are arranged in clusters consisting of one to four rows of 

 cells, separated by bundles of fibers. 



The prevailing form of cell is rounded; elliptical ones are much 

 less numerous. Some are irregularly polyhedral on account of 

 pressure of the surrounding cells. The cells are nearly uniform 

 in size. They varied in length between 16 and 38 m and in 

 breadth between 14 and 27 m- The larger and smaller cells are 

 comparatively few. The nuclei are comparatively large but are 

 proportionally smaller than in the ganglion of the tenth nerve. 



G. SENSORY GANGLIA OF THE SPARROW 



1. Spinal ganglia 



Observations were made only on the spinal ganglia of 

 the sparrow. The ganglia of the lumbar region are quite small, 

 one measuring about 0.5 mm. in length and about 0.33 mm. 

 in breadth. The cells are much more numerous at the periphery 

 than at the center of the ganglion. In the peripheral region there 

 is no grouping of cells, while in the central part the cells are 

 arranged in elongated groups of one to three rows. 



