NERVUS TERMINALIS: MAMMALS 



49 



very delicate myelin sheaths are present, as brought out by 

 iron-haematoxylin staining. More slender nerve strands in the 

 same preparation showed a smaller number of myelinated fibers. 

 In longitudinal sections (fig. 35.) the myelin sheaths are shown 

 to continue without interruption for considerable stretches. 

 They measure from 1.5 /i to 2 m in diameter. 



Sections of the main trunk peripheral to the ganglionic masses 

 revealed a much larger number of myehn sheaths. In the sec- 

 tion illustrated (fig. 37) which was stained by the Weigert method, 

 sixty-four dehcate sheaths are visible. Attention may also be 

 called in- this connection to the many fascicuh, fifteeen in num- 

 ber, which enter into the formation of the larger bundle. 



Fig. 37 Transverse section of main trunk of nervus terminalis of beef, show- 

 ing distribution of myelinated fibers. Formalin fixation, Weigert stain. X 360. 



4 



Great care was exercised to prevent decolorizing any of the 

 sheaths during the process of differentiation, when those meth- 

 ods were employed which required caution. In view of the par- 

 tial degeneration which had taken place in some of the sheaths, 

 it is possible that this process had reached a stage in some fibers 

 at which the staining methods employed were no longer effective 

 in differentiating the myelin. It is believed, however, that the 

 majority of myelinated fibers were stained. The remaining por- 

 tion of the nerve strand was assumed to be made up of unmye- 

 linated fibers. These observations were subsequently confirmed 

 in material which was fixed in osmic acid shortly after the animal 

 was slaughtered. 



THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 30, NO. 1 



