Hardestv, Medulla Spinalis of the Elepliant. 155 



section as a ring enclosing the cell-bodies of the nucleus within 

 its center. For man, the much fewer axones of this 

 type cour.-ing in the nucleus are described, see Barker 

 ('99). as being split into two divisions, one of which courses at 

 each side of the nucleus. Neither of these conditions is true 

 for the elephant. Here the mcduUated axones predominate 

 greatly over the ccrll-bodies and prevail equally over the whole 

 domain of the nucleus forming a compact fasciculus (Figs. 10, 

 14. and 15) in which cell-bodies are sparsely scattered. 



The number of the cell-bodies composing the nucleus dor- 

 salis of the elephant was found relatively small in all of the 

 sections examined. The number, however, was found to be 

 greater in thoracic IV than in thoracic II and greater even than 

 in thoracic VIII. The counts involved only the cell-bodies of 

 the large approximately spherical type supposed to be peculiar 

 to the nucleus dorsalis. The average number per secdon was 

 determined for each of the above segments. The sections were 

 30 micra thick and, to avoid twice counting, only those cell- 

 bodies containing nucleoli were counted. The counts involved 

 the nucleus dorsalis of the two sides of four sections from each 

 of the three segments. In other words, for each segment the 

 cell-bodies in eight sections of the nucleus were counted and 

 the average number determined for each section of 30 micra. The 

 average for thoracic VIII was 3 cell-bodies per section of the nu- 

 cleus ; for thoracic IV, 8 cell-bodies, and for thoracic II, 5 cell- 

 bodies. Though the counts are inadequate to base conclusions 

 upon, they suggest that the number increases from thoracic VIII 

 to thoracic IV or III and then decreases as the nucleus decreases. 



The average mean diameter of the cell-bodies counted was 

 found to be 43.5 micra. It will be seen later that this is little 

 more than half the average mean diameter of the large cell- 

 bodies of the columna anterior of the intumescentia cervicalis. 



It should be mentioned that in addition to these large ap- 

 proximately spherical cell bodies which were counted and 

 measured, each section of the nucleus dorsalis contained quite 

 a number of much smaller cell-bodies. These were of the small 

 stellate and fusiform type scattered abundantly throughout the 



