i66 Journal of Comparative Neurology. 



lines shown crossing the cell-bodies are the jidentical diameters 

 measured. The averages given in the Table were obtained by- 

 dividing by 10 the sum of the mean diameters of the ten cell 

 bodies measured. 



In Table III as well as in Plate XIII it can be seen that in 

 passing from the elephant to the bat there is a general and fairly 

 gradual decrease in the size of the cell body. This decrease 

 however is very roughly and not at all directly proportional to 

 the decrease in the size of the animals. The results give the 

 dog as large a cell body as man, while the monkey has almost 

 as large as the hog, and the difference between the rat and rab- 

 bit is equally as far from expressing the difference in the size 

 of the two animals. Only the general statement may be made 

 that the smaller mammals have the smaller cell-bodies in the 

 columnae anteriores of the intumescentia cervicalis. 



It will be noted that the bat seems to possess an appreci- 

 ably larger cell-body than the mouse. This indicates a peculiar- 

 ity of this animal shown by none other in the series. Sections 

 from its intumescentia cervicalis revealed a lateral group corn- 

 posed of cell-bodies much larger than any others in the section. 

 This group is the chief component of the columna lateralis of 

 this animal. Their position leads one to assume that these large 

 cell-bodies have to do with the innervation of the wings of the 

 bat, a modification of the fore limbs not possessed by any 

 other of the mammals in the series. Since the original plan 

 called for measurement of the largest cell-bodies only, the 

 measurements for the bat w^ere made entirely from this group. 

 The average would have been less than that for the mouse had 

 the measurements been made from the much smaller cell-bodies 

 occupying the other portions of the columna anterior. 



In a few instances cell-bodies of neurones of animals vary- 

 ing in body weight have been measured by previous investiga- 

 tors. These show variations in size similar to those shown in 

 Table III. 



Kaiser ('91) made some measurements of the cell bodies 

 of the cervical region from a series of five mammals. His tis- 

 sue was fixed exclusively in Muller's fluid, and his object be- 



