174 



JouKNAL OF Comparative Neurology. 



the transverse sections of the medulla spinalis, and in no higher 

 ratios than the variations in the areas of the substantia grisea 

 contained in the sections. 



4. That in the larger mammals especially, but a small 

 fraction of the entire neurone is represented in the cell-body or 

 the ordinarily visible portion of the neurone. 



5. That the variations in volume of the entire neurone 

 occur in higher ratios and are therefore more nearly in propor- 

 tion to the variations in body weight than either the volumes 

 of the cell-bodies, the areas of the transverse sections of the 

 medulla spinalis, or the areas of the substantia grisea in the 

 sections. 



Some interesting relations may be seen by comparing the 

 areas of the substantia grisea and the substantia alba in the 

 transverse sections from the different members of the series, 

 and also by comparing the area of the section of the cell body 

 with the area of the section of the substantia grisea containing 

 it. The data for these comparisons are contained in Table III, 

 but that the comparisons may be more easily made and the 

 relations more readily seen, the necessary computations are 

 made and tabulated as follows : 



TABLE IV. 



