754 



Nachdruck verboten. 



The Form and Relations of the Nerve Cells and Fibers in 

 Desmognathus fusca. 



(Preliminary Notice.) 



By Pieeee A. Fish, 



B. S. Instructor in Physiology, Vertebrate Zoology and Neurology, 



Cornell University, Ithaca, New York. 



With 2 figures. 



In the study of the neuraxis (central nervous system) of the 

 Amphibia much stress has been placed upon the direction and relation 

 of the fiber tracts while the nerve cells have been practically ignored. 

 Both are of equal importance and the neglect of the cells has pro- 

 bably been due to the fact that ordinary methods fail to demonstrate 

 their appendages to any length and the apparent simplicity of structure 

 has not seemed to merit a very extended description. 



The Golgi-Cajal silver nitrate method has brought out such an 

 abundance of detail and so greatly facilitated the tracing of the most 

 delicate ramifications that new and unexpected conditions may be 

 looked for in some of the more simple animal forms. 



In the Desmognathus the neuraxis presents a very simple 

 appearance, being composed of an ental cellular layer or cinerea and 

 an ectal fibrous layer or alba. The endymal cells immediately surroud- 

 ing the neurocoele agree in all essentials with the descriptions of 

 Oyarzun and others, being piriform in outline, the blunt end of the 

 cell bounding the cavity and the peripheral end extending into a pro- 

 cess which divides into numerous smaller ones in the cinerea as well 

 as in the alba. The processes are irregular or ragged in outline and 

 many of them extend as far as the periphery of the neuraxis were 

 they may end taperingly or by means or a slight enlargement. The 

 processes are exceedingly dense and much interlaced and without 

 question form the greater amount of the supporting substance. 



Another form of cell is found at the ectal boundary of the cinerea 

 and its outline varies from a somewhat blunt pear shape to a dis- 

 tinct fusiform cell with the long axis extending perpendicularly to 

 that of the endymal cells, or in other words more or less parallel 

 with the periphery of the neuraxis. They are always characterized 

 by the presence of more than one process. These processes were 



