Hardesty, Medulla Spinalis of the Elephant. 127 



ually through the series, but neither the diameters nor the rate 

 of decrease are constantly proportional to the size of the animal. 



4. In proportion to the size of the body, the smaller 

 mammal has a very much heavier medulla spinalis than the 

 larger mammal. 



5. The area of the transverse section of the medulla 

 spinalis is more expressive of the relation to body weight than 

 the diameters of the transverse section, and the rate at which 

 the areas vary through the series is more nearly proportional to 

 the variations in body weight. 



6. The areas of the substantia grisea in transverse sec- 

 tion, while in general decreasing gradually through the series, 

 do not vary in accord with the variations in the size of the 

 animals. 



7. The average mean diameter of the cell bodies of the 

 columnae anteriores in the intumescentiae cervicales decreases 

 gradually through a series of mammals of diminishing body 

 weight. 



8. The volume of the cell-body of the neurones varies 

 more nearly in proportion to the variations in the size of the 

 animals than does the diameter of the cell body. 



9. The smaller mammals have the smaller cell-bodies, but 

 in proportion to the size of the body, the smaller mammal pos- 

 sesses a very much larger cell-body than the larger mammal. 



10. Through a series of mammals of diminishing body 

 weight, the volume of the entire neurone bears a more constant 

 ratio to the size of the body than either diameter or area, and 

 the variations in the volume of the entire neurone are more 

 nearly proportional to the variations in the size of the body 

 than either the diameter of the cell-body, the volume of the 

 cell-body or the area of the transverse section of the medulla 

 spinalis. 



ir. Table IV, showing actual and relative areas of sub- 

 stantia grisea and substantia alba in transverse sections from the 

 different mammals, and giving the ratios between these areas 

 and the areas of the cell bodies in section. 



12. Through a series of mammals diminishing in body 



