Hardesty, Medulla Spinalis of the Elephant. 139 



missurae albae posterior and anterior are especially noticeable 

 because of the numerous axones in them, whereas, what he 

 must have taken for such are, instead, the only visible vestiges 

 of the entire commissura grisea proper (see figures) and, while 

 the stained section shows these to contain medullated axones 

 belonging to the commissures mentioned, they are in fact com- 

 posed largely of connective tissue and neuroglia. Kop.sch fur- 

 ther mentioned that the canalis centralis could not be recognized. 

 Because of the presence of the above-named fasciculi the ca- 

 nalis centralis is not situated centrally as is usually ob'^erved in 

 other animals, but it could be recognized in the author's speci- 

 men {c c, Fig. 8) when one knew where to look for it. 



F'igures 2, 4, 7 and 1 1 are reduced to scale from photo- 

 graphs in which the actual sections were enlarged about ten di- 

 ameters. They show the relative proportions of four transverse 

 sections taken at the levels indicated in Fig. i. Each is accom- 

 panied by an outline similarl}' reduced, in which certain of the 

 parts are named. 



Comparing the sections with those of the medulla spinalis 

 of man at corresponding levels, attention is drawn to the ap- 

 pearances of the gray figure (substantia grisea) as a whole. 

 While much larger actually, its size in proportion to the amount 

 of substantia alba does not seem so great as in man. The two 

 sides of the gray figure seem widely separated. This latter ap- 

 pearance is due to some extent to the unusual occurence of 

 substantia alba (fasciculi above-mentioned) in the substance of 

 the commissura grisea, changing its optical appearance from 

 that of other parts of the gray figure. The substantia gelatinosa 

 RoLANDi is greatly developed especially in the cerv^ical and up- 

 per thoracic segments {S. g. R., Figs. 5, 8 and 10). Kopsch 

 describes an extra abundance of substantia gelatinosa in the 

 lumbar segments also. The caput of the columna posterior is 

 separated from the periphery of the section by a comparatively 

 thick zone (Lissauer's zone?) of substantia alba. It will be re- 

 membered that in the smaller manmials the caput often extends 

 to the periphery practically. In the cervical segments, the 

 fasciculus gracilis is so well defined that its boundaries may be 

 seen with the unaided eye. 



