1 2 Journal of Comparative Neurology and Psychology. 



sarcolemma than under it, though at times a knob could be 

 observed to penetrate deeper towards the fibrillated sarcous 

 substance. It was noted that in every ending the fibrillated 

 sarcous substance was sharply marked off, so that it was always 

 easy to determine that the nerve terminals did not penetrate 

 within or even as far as the fibrillated muscle substance. 



On the ultraterminal fibrillae a sheath could at times be 

 seen. This sheath followed closely the convolutions of the 

 nerve, and could be traced to the neighboring muscle to which 

 the nerve was going ; there it blended with the sarcolemma. 

 The nerve terminals and end-knobs differed in no respect from 

 the corresponding parts of the main nerve stem (Fig. 6). 



In short the primary divisions of the nerve ending lie over 

 the sarcolemma, and are surrounded by both the neurilemma 

 and the sheath of Henle ; the ultimate fibrils lie in a homo- 

 geneous substance within the sarcolemma, and are covered by 

 a cap formed by the blending of these sheaths with the sarco- 

 lemma. The open condition of the sheath of Henle, as described 

 by SiHLER, was not observed. 



Concluswfis. 



The so-called nerve ending of the frog is to be regarded 

 in the first place as the peripheral separation of the contents of 

 the axis cylinder, by which separation it is able to spread itself 

 over a relatively wider area. As a nerve fiber may attach itself 

 to various muscle fibers, so the fibrillae of the ending may like- 

 wise reach over to adjacent muscle fibers. Those fibrils which 

 detach themselves near the central point of separation are, as a 

 rule, larger and more easily stained than the more distal ones, 

 and are comparable to the non-meduUated fibers which may 

 arise from the medullated nerve stem. One can note that the 

 secondary endings to which they give rise are often comparable 

 in form to the primary endings, though having a smaller num- 

 ber of branchings ; this would suggest that the amount of 

 branching which is possible bears a relation to the diameter of 

 the fiber. 



A plexus is often^ formed by the nerve terminations (Fig. 



