522 A. J. LINOWIECKI 



whicli represents the postero-lateral quadrant of the cord, its 

 posterior and lateral borders are quite apparent. In the thoracic 

 and linnbar segments the tract is stained a little deeper than the 

 rest of the white substance of the cord but its outline is not very- 

 sharp. In the lumbar region the tract does not extend so far 

 laterally but appears to hug the posterior horn. Its exact out- 

 line can not be made out. In the sacral cord the tract is more 

 indistinct and scarcely perceptible. 



Examination of the Pal-Weigert sections failed to reveal any 

 indication of the outline of the tract. The white substance of 

 the cord stained equally throughout and the myelin sheaths 

 appeared equally distributed. The axons in the pyridine-silver 

 preparations greatly outnumber the myelin sheaths seen in the 

 Pal-Weigert sections. 



The largest of the medullated fibers were equal, in diameter, to 

 those in the rabbit cord and measured 17.44;^. The majority of 

 these fibers, however, measured from 9.67/i to 12.27^1 in diameter. 



Ground-mole {Scalopus aquaticus) 



The presence of a pyramidal tract located in the anterior 

 funiculus of the cord of the ground-mole was discovered by 

 Draeseke ('04). He speaks of it as being an oval gray field 

 situated in the anterior funiculus on either side of the anterior 

 median septum which divides it. His sections were prepared 

 by the old Weigert method after being hardened in Miiller's 

 fluid, formalin and alcohol. To him the tract appeared like the 

 gray substance about the central canal and he says that few 

 medullated axons are present. In his study of the tract he also 

 utilized the different modifications of the Weigert stain as well 

 as the hematoxylin-eosin stain and could readily trace the tract 

 through the thoracic region. Following the tract toward the 

 brain he found no decussation of the pyramids. 



In the sections of the mole's cord stained by the Pal-Weigert 

 method, examined in the course of this work, a gray oval tract 

 was found in the anterior column just about midway between 

 the transverse part of the gray substance and the anterior pe- 



