208 BULLETIN OP THE UNIVERSITY OF WISCONSIN. 



cide, except in the connections between the fibers and cells which 

 I did not investigate, with those of Stirling in the newt. He 

 savs : 



"A large number of nerve cells are found along the whole course of 

 these mixed nerve strands and occur singly or in groups, and are 

 usually most numerous where branches are given off. 



"They are not confined to the main trunks, however, but recur singly 

 or in small groups in the larger nerve branches. Sometimes the cells 

 lie singly between the sheath of the nerve and the nerve fibers, whilst 

 others lie crushed up as it were between the nerve fibers. As already 

 remarked, they are most numerous where a nerve twig is given off 

 from the main mixed strand. In these small aggregations of nerve 

 cells it is easy to trace the course of a medullated fiber sweeping clear 

 through the mass, and forming no connections with the cells, whilst, 

 occasionally, one may see a connection between a nerve cell process 

 and one of the non-medullated fibers. The shape of the nerve cells 

 seems to vary considerably; some appear to be bipolar, whilst others 

 are polygonal and have several processes, one or more of which may 

 become continuous with a non-medullated fiber. Each cell contains a 

 relatively large nucleus usually placed eccentrically, and the body of 

 the cell may or may not be enclosed in a capsule. Other nucleated 

 masses of protoplasm devoid of processes lie amongst the nerve fibers, 

 and it is not clear what is their exact nature. Perhaps they may 

 represent developing nerve cells." 



TECHNIQUE. 



The specimens were killed by chloroform, although some were 

 used that had been dead for a few hours, and those used for the 

 w r ork on the epithelium were killed by pithing. The lungs were 

 removed by opening the body cavity at the left side of the 

 median ventral line and then cutting through the ventral mesen- 

 tery, which allowed me to throw back the flap of the body-wall, 

 thus exposing the whole of the viscera to view. The lungs were 

 carefully blown up with a syringe introduced through the mouth, 

 into the glottis. This made the lungs very prominent and it 

 was a comparatively simple matter to cut through the fold of 

 peritoneum, which attaches the lung to the body-wall. Care 

 was exercised, in handling the lungs, not to puncture them, as- 



