NERVUS TERMINALIS: TURTLE 437 



smallest was 5.3 m in diameter. The average size of the entire 

 one hundred nuclei was 8.5 n. These cells were divided into 

 two groups, those with a nuclear diameter greater than 8.2 yu 

 and those whose nuclear diameter was less than this, down to 

 5.3 M which was the smallest found. While this division was 

 somewhat arbitrary, there was sufficient ground for it in the 

 character of the cells, aside from their size, to make it appear 

 justifiable. The smallest cells (fig. 10) had considerably less 

 cytoplasm surrounding the nucleus, both relatively and ac- 

 tually. Only various stages of the bipolar condition were ob- 

 served in these smaller cells. They were found closely packed 

 together in the central portion of the ganglion, while the larger 

 cells were nearer the periphery. 



As indicated in the table, the fifty-two cells which showed a 

 nuclear diameter less than 8.2 fx had an average diameter of 

 7.3 /x. The forty-eight cells whose nuclear diameter was greater 

 than 8.2 ^t were found to have an average nuclear diameter of 



9.8 m. 



The smaller cells (fig. 10) may correspond to the small ganglion 

 cells found in the spinal gangha of mammals by Dogiel ('08), 

 Ranson ('12), and other workers, but it seems likely that some 

 of them at least represent cells of the larger type which have not 



* 



Fig. 9 Cells from the peripheral portion of the first thoracic spinal ganglion 

 of a turtle embryo of 10-mm. carapace length. Iron-hematoxylin stain. X 500. 



Fig. 10 Cells fropi the central portion of the same ganglion from which figure 

 9 was drawn. Turtle embryo 10-mm. carapace length, iron-hematoxylin stain. 

 X 500. 



Fig. 11 Cells from the gasserian ganglion of turtle embryo of 10-mm. cara- 

 pace length. Iron-hematoxylin. X 500. 



Fig. 12 Cells from the third thoracic sympathetic chain ganglion of turtle 

 embryo of 10-mm. carapace length. Iron-hematoxylin. X 500. 



Fig. 13 Cells from the ciliary ganglion of turtle embryo of 10-mm. carapace 

 length. Cells of smaller type indicated at A, and the larger type at B. Iron- 

 hematoxylin. X 500. 



Fig. 14 Cells from the sphenopalatine ganglion of turtle embryo of 10-mm. 

 carapace length. Ii-on-hematoxylin. X 500. 



Fig. 15 Cells from the peripheral cell clusters of the nervus terminalis of a 

 turtle embryo of 10-mm. carapace length. Iron-hematoxylin. X 500. 



Fig. 16 Cells from the central root clusters of the nervus terminalis of a turtle 

 embryo of 10-mm. carapace length. Iron-hematoxylin. X 500. 



