NERVUS TERMINALIS: TURTLE 439 



writer. In all cases, however, whether or not arranged in a 

 distinct group, small ganglionic cells were found in the ganglion. 

 These differed not only in size, but also in form, from the larger 

 more typical cells. Carpenter considers the large cells in the 

 chick to be derived from the midbrain and to have migrated 

 along the oculomotor nerve to the ciliary ganglion. The small 

 cells he believes to be sympathetic cells which have migrated 

 forward along the ophthalmic nerve. 



Fifty of the large cells were measured. The largest had a 

 nuclear diameter of 12.4 n, the smallest of 7 ix. The average 

 nuclear diameter of the fifty cells was 9 /i. While the size of 

 these nuclei approached that of the large spinal ganglion cell 

 nuclei, and the largest found in the ciliary ganglion even ex- 

 ceeded the largest observed in the spinal ganglia, the amount of 

 cytoplasm surrounding the nuclei of the ciliary ganglion cells was 

 considerably less, as may be seen by comparing figures 9 and 13, 

 B. The actual size, therefore, of the ciliary ganglion cells was 

 somewhat less than that of the large spinal ganglion cells. 



Twenty- two cells of the smaller type were measured. These 

 were found in several adjacent sections, forming a distinct mass 

 in the embryo on which the measurements were made. The 

 largest of these cells had a nuclear diameter of 7.9 i^. The 

 smallest was 5.3 m, and the average of the twenty-two was 6.4 /x. 

 As figure 13 (A) indicates, there were also differences in the form 

 of the cells and in the amount of cytoplasm siu"rounding the 

 nucleus, as compared with the large cells. 



There remain the cells of the sphenopalatine ganglion, which 

 form a relatively smaU cluster. These cells are of quite uniform 

 size and structure (fig. 14) with spheroidal, eccentrically located 

 nuclei. Most of them were in the primitive bipolar stage of dif- 

 ferentiation. Except that there was less individual variation 

 among these cells than among those found in the clusters of the 

 nervus terminaUs, to be described, the sphenopalatine cells may 

 be said to resemble the terminalis cells more closely than any of 

 the other ganghonic cells studied. Of fifty sphenopalatine cells 

 which were measured, the largest had a nuclear diameter of 

 8.1 iJL. The smallest was 5.3 n, and the average for the fifty 

 nuclei was 6.74 n. 



THE JOUBNAL OF COMPARATIVE NBUBOLOQT, VOL. 30, NO. 5 



