Hardesty, Medulla Spinalis of the Elephant. 157 



they are not distinctly distributed in groups such as are, for 

 example, described by Waldeyer ('88) for the medulla spinalis 

 of the Gorilla. Sometimes in the same section the cell-bodies 

 will be more distinctly grouped on one side than on the other. 

 In the section from cervical VI (Fig. 7), on the right side of 

 the figure the cell-bodies of the columna lateralis (lateral horn) 

 are gathered into the ventro-lateral, the two posterolateral and 

 the medio-lateral groups quite distinctly, while on the other 

 side, no such grouping is apparent. In the latter, these cell- 

 bodies, supposed to send motor axones to the muscles of the 

 fore limb, are quite evenly scattered over the whole area. The 

 ventral group, almost absent on the right side of the section, is 

 in other sections quite evident. The mesial group, in both its 

 ventro- and postero-divisions, can in some sections be deter- 

 mined, while in others the cells composing it are i&w and scat- 

 tered along the entire mesial border. This group, innervating the 

 muscles of the vertebral column is, of course, represented 

 along the entire medulla spinalis, and is practically alone pres- 

 ent in the narrow columna anterior of the mid-thoracic segments 

 such as is shown in Figure 1 1. 



In general the cell bodies of the columna anterior are no- 

 ticeably large. Measurement of the ten largest lound in three 

 sections of the intumescentia cervicalis including and adjacent 

 to that shown in Figure 7, gave an average mean diameter of 

 84.4 micra. 



Comparative Studies, 



The above observations upon the medulla spinalis of the 

 elephant suggested the making of certain comparisons between 

 it and that of other mammals. Toward this end material was 

 prepared in a similar way from eleven other animals. Thus, in- 

 cluding the elephant, the following studies will deal with a series 

 of twelve mammals. 



It was thought that the comparisons might be of more 

 interest if the series included mammals with body weights vary- 

 ing from the largest to the smallest. Despite many e fforts 

 the series is not so satisfactory in this respect as could 



