278 E. VICTOR SMITH 



The cells at the periphery are irregularly polyhedral in shape 

 as a result of pressure from neighboring cells, while in the central 

 region they are rounded to elliptical, the rounded forms pre- 

 dominating. The cells are relatively small. The largest meas- 

 ured had a uniform diameter of 27 m, with a rounded nucleus of 

 8 M- The smallest cell measured was round, with a diameter of 

 12 /i and a rounded nucleus of 6 //. The nucleus, as a rule, is 

 situated near the center of the cell and is relatively quite large. 

 A single darkly stained nucleolus was seen in each nucleus. The 

 processes are fine and take a direct course as they emerge from 

 the cells. No glomeruli or implantation cones were observed. 



The spinal ganglia between the brachial and lumbar regions 

 are very small, one of the larger of them measuring 0.5 mm. in 

 length and 0.25 mm. in breadth. As shown in figure 40, the cells 

 are crowded very close together, imparting to them irregular 

 polyhedral forms. There is no grouping of cells such as is com- 

 monly seen in the ganglia of larger birds. The cells are smaller 

 than those of the lumbar gangUa, the largest measured being 

 19 by 25 M. One of the smallest was triangular in shape and 

 measured 11 m from base to apex. The nuclei are nearly all 

 rounded and are comparatively large. Most of the nuclei had a 

 single deeply stained nucleolus, but in a few nuclei there were 

 seen two nucleoli (fig. 40). A very delicate but clearly defined 

 capsule (not shown in fig. 40) surrounds each cell. 



IV. SUMMARY 



The sensory ganglia of birds vary in size somewhat in propor- 

 tion to the size of the bird. In the individual bird the order of 

 size of the ganglia beginning with the largest is Gasserian, bra- 

 chial, tenth, lumbo-sacral, the other spinals, and the ninth. The 

 brachial ganglia are relatively larger in birds that use their wings 

 much. 



In larger ganglia the cells are more numerous about the 

 periphery and in this position lack sympathetic arrangement, in 

 the central region the cells are arranged in elongated groups. 

 The smaller ganglia do not exhibit a definite grouping of cells. 



