178 Prof. J. N. Langley. On Nerve Endings and on [May 24, 



mode of action of nicotine given above. It shows that if nicotine has an 

 action on muscle, so also has curari. But some other form of experiment 

 is required to decide whether nicotine does, in fact, act upon the muscle 

 direct. 



It is clear that what is required is to examine the behaviour of the muscle 

 when no nerve endings are present. A means to this end is to cut the nerve 

 and allow it time to degenerate. It is known that after section, nerve-fibres 

 degenerate up to their point of entry into the muscle fibres and it has been 

 almost universally assumed that the nerve endings, which are but the 

 terminal branches of the nerve, degenerate also. It is, however, as I have 

 already said, not uncommonly believed that the nerve endings degenerate 

 more slowly than the nerve-fibres, and some doubt has been expressed as to 

 whether they degenerate at all. 



This question must then first be examined. The degeneration of the 

 nerve endings after section of the nerve-fibres has been taken so much as a 

 matter of course, that there are, so far as I know, two papers only published 

 on the subject. 



The earlier investigations were made by Sokolow,* on the gastrocnemius 

 muscle of the frog. He examined the muscle for nerve endings by the gold 

 chloride method, 14, 28, 32 and 44 days after section of the sciatic nerve. 



Fourteen days after section of the sciatic nerve, no change was observable 

 in the nerve endings. In the other three cases, good staining of the muscle 

 was apparently only obtained in that taken 32 days after section of the 

 nerve, but it may perhaps be assumed that the changes described were 

 observed, though less satisfactorily, in the other two. According to Sokolow, 

 the different nerve endings undergo change at very different rates, so that in 

 all cases some normal nerve endings remained. Those which were altered, 

 but still visible, showed fine dark stained granules in a basis staining 

 less than normal. The alteration was sometimes only at the ends of the 

 hypolemmal fibres, and different hypolemmal fibres of the same ending- 

 showed different degrees of change. 



In other cases, some or all of the hypolemmal fibres had completely 

 disappeared. 



In the latter type, the nerve-fibre with fragmented myelin was traced up 

 to the muscle and Sokolow states that the absence of the nerve ending was 

 not due to imperfect staining. In some instances he describes the spaces left 

 by the nerve endings as being filled with a fine deposit of gold. 



Although these observations leave something to be desired, they do, I 

 think, show that the nerve ending undergoes first granular degeneration and 

 * Sokolow, 'Archives de Physiol.,' 1874, p. 300. 



