Wilson, Motor Endings of the Frog. 9 



At no time have I seen any appearance of an intermuscu- 

 lar nerve plexus formed by these fibrillae. I am inclined to 

 regard the motor fibrillae which pass into the intermuscular con- 

 nective tissue and there disappear, as either broken fibrillae or 

 fibrillae only partially stained. 



TJie relatio7i of the nerve ending to the muscle fiber. — The re- 

 lation of the nerve endings to the sarcolemma has been 

 much disputed. Of recent writers who have discussed this 

 question with reference to the muscle of the frog, the following 

 only need to be referred to : Huber-DeWitt,^ after a careful 

 investigation, come to the conclusion that the terminals lie un- 

 der the sarcolemma and are devoid of any sheath. Sihler,^ on 

 the other hand, using a method which he finds particularly ap- 

 plicable to this research, considers that the endings lie over the 

 sarcolemma and that the end of fibrils are covered "down to 

 their tips with the sheath of Schwann;" further that the sheatk 

 of Henle is open (vervvachst mit nichts) and does not cover the 

 end fibrils, but that the nerves emerge from it as an arm from 

 a sleeve (wie der Arm aus dem Aermel ) ; at the same time, he 

 does not deny that there are points where the nerve substance 

 and the muscle fiber may come into contact. 



In fresh muscle fibers in which the nerves have been stained 

 by the intra-vitam methylene blue method, I have found that, 

 while the majority of the terminal branches lie in close relation 

 to the muscle fiber, at times a terminal fibril is seen to rise 

 some distance above the muscle fiber, and occasionally such a 

 nerve fibril sends down to the muscle fiber little rootlets com- 

 parable to those described by Sihler. But sooner or later 

 even in such nerve fibrils the ultimate terminals come to lie on 

 the muscle fiber. While the occurrence of such nerve fibrils 

 may be held to prove that the larger fibrils may be epilemmal, 

 there is nothing to show what the !-elation of the terminal fibrils 



' Huber-DeWitt : Nerve Endings in Muscles. /. Comp. Neurol., 1897, 

 VII, p. 185. 



' Sihler : (a) The Nerves of the Capillaries with remark on Nerve End' 

 ings in Muscles. J. Exp. Med., 1901, V, p. 511. (b) Neue Untersuchungen 

 iiber die Nerven, etc. Zeit. f. wiss. ZooL, Leip., 1900, LXVIII, pp. 351 and 

 375- 



