264 E. VICTOR SMITH 



cells of sympathetic type in sections of sensory ganglia. Careful 

 search, however, did not show the presence of sympathetic cells 

 on the sensory side of the ganglion. There is proximity without 

 actual mixture of the cells. Non-medullated fibers in large num- 

 bers crossed from the sympathetic to the sensory sides. 



B. SENSORY GANGLIA OF THE OWL 



1 Spinal ganglia 



There is considerable variation in the size of the spinal ganglia 

 of the owl; those of the brachial and lumbo-sacral regions are 

 relatively large, being about the size of the Gasserian, and the 

 cervical and the remaining dorsal and lumbar are small. In the 

 large ganglia the cells are more numerous at the periphery than 

 at the center, but lack sympathetic arrangement. In the smaller 

 ganglia the cells are closely packed and are not divided into groups. 



The cells of the spinal ganglia of the owl, although considerably 

 smaller, conform closely in shape to those of the chick. They 

 are for the most part rounded to elliptical and embrace only a 

 limited number of forms that are so characteristic of the Gasserian 

 and vagus of the same bird. The major diameters vary between 

 16 and 50 fj., and the minor between 8 and 27 ijl. Large cells occur 

 infrequently with major diameters above 45m and minor above 

 25 IJL. In contrast with these conspicuously large cells are present 

 small cells, some of them not more than 16 ^ long and 8/x wide. 

 While there are gradations between the largest and the smallest, 

 most of thje cells are of a medium size with long diameters of 20 

 to 27 At and short diameters of 18 to 22 /x. 



The centrally located nuclei are round to elliptical and vary in 

 major diameter between 5 and 10m, and between 4 and 8m in 

 minor diameter. The smallest nucleus measured was 4 by 5 m 

 and the largest 8 by 9. 



The ganglia of the brachial region show two classes of cells, 

 the division being based on size. Those of the larger size con- 

 stituted about 20 per cent of the entire number of cells in the 

 ganglion, and had for their average major diameter 34m, and for 



