440 O. LARSELL 



With these measurements as criteria, a comparison may be at- 

 tempted between the ganghonic cells of the nervus terminalis and 

 these other cells of well-recognized function, with the purpose in 

 mind of throwing more light on the relationship of the nervus 

 terminalis. 



Many of the terminahs cells (figs. 15 and 16) have a peculiar 

 elongated form not met with elsewhere in the ganglia which were 

 subjected to observation. This is well illustrated in some of the 

 cells represented in figure 15. Only two processes were observed 

 in any of these cells, and these were in most cases continuous 

 with the longer axis of the cell. In view of the findings of 

 McKibben ('14) in the dogfish and of the various authors who 

 have made observations on the ganglion cells of the terminalis 

 in the mammals, it seems likely that this bipolar condition is 

 developmental in the turtle. 



The nuclei were elongated in many cases and many were also 

 considerably distorted otherwise, as the figures indicate. This 

 was more frequently the case in the peripheral clusters than in 

 those withm the cranial cavity. These conditions made the 

 terminalis cells more difficult 1:0 measure, so that the results 

 obtained represent the mean of several measurements on many 

 of the nuclei. In order to determine the difference in size, if 

 any, between the cells which were located in the ganglionic 

 swelling near the central roots of the nerve and those along the 

 olfactory and vomeronasal nerves outside the cranial cavity, 

 the measurements were tabulated separately for the two groups. 

 Thirty cells from the centrally located ganglion (fig. 16) indicated 

 an average nuclear diameter of 6.72 m, the largest being 8.4 ix, 

 and the smallest 5.3 m (table 1). The fifty cells of the peripheral 

 clusters (fig. 15) which were measured indicated an average 

 nuclear diameter for the entire number of 6.7 ju, practically the 

 same as that of the centrally located cells. The largest nucleus 

 of the peripheral clusters was 8.8 m in diameter, the smallest 

 was 5.3 fx. A larger number of measurements was not made 

 because the variation in size was not pronounced. Only three 

 of the eight}^ nuclei measured were larger than 8.1 m? i-e., more 

 than 1.4 yu larger than the average. This amount indicates the 



