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



Fig. 6. — Nerve ending in sartorius muscle of frog three weeks after nerve section. 



Methylene blue stain. The tint of the several parts of the nerve ending in 

 the figure represents roughly the degree of stain, but the tint of the hypo- 

 lemmal fibres, and, to a less degree, that of the nuclei, is too deep. 



Lastly, Tuckett has investigated the nerve endings in the flexor profundus 

 muscle of the pigeon, by the methylene blue method. He finds that the 

 hypolemmal fibres show granular degeneration in two days or less, and that 

 after three days they disappear. The details of his work will be published 

 shortly. 



As the results of these various observations, we may then, I think, safely 

 conclude that after section of a nerve, the nerve endings undergo first 

 granular degeneration and then absorption. 



And, if this be granted, it is clear that we can determine whether nicotine 

 does or does not act on muscle by administering it a sufficient time after 

 a motor nerve has been cut. 



I have examined* the reaction of the gastrocnemius muscle of the 

 fowl, 6, 8, 27, 38, and 40 days after section of the external peroneal nerve 

 which innervates it. In all cases a contraction was obtained essentially 

 similar to the normal nicotine contraction, the only difference apparently 

 observed being an increased response to small doses of the poison, indicating 

 an increased excitability after denervation, such as has been described in some 

 cases of unstriated muscle after nerve section. 



Since the contraction is certainly not decreased, and may be increased, by 

 degeneration of the nerve endings, the nicotine contraction must be produced 

 by an action on the muscle and not on the nerve endings. 



Passing now to the effect of curari. On the fowl's gastrocnemius muscle, 

 after degeneration of the nerves, curari is still capable of reducing the 

 nicotine contraction. The only difference is that it is — so far as the 

 experiments go — a less powerful antagonist ; a fact probably related to the 

 apparent increased excitability to nicotine already mentioned. Curari, then, 

 must also have an action on the muscle substance. 



* Op. cit. supra. 



