1906.] Special Excitable Substances in Cells. 179 



1 



then absorption. A point which raises some doubt in my mind is a brief 



statement by Sokolow that in all cases contraction was still obtained by 

 stimulating the nerve. It seems unlikely that after nerve section some of 

 the nerve-fibres and nerve endings should be normal, whilst others had so far 

 degenerated that the nerve endings had completely disappeared, or that the 

 conductivity of the nerve should last as long as 44 days. 



The second published work on this subject is by Huber.* His observa- 

 tions were made on the interosseus muscles of the rabbit, the posterior tibial 

 nerves being crushed to interrupt continuity. The nerve endings were 

 stained with methylene blue. On the second day after the nerve crashing, 

 some of the hypolemmal fibres showed round or oval thickenings staining 

 deeply with methylene blue, these rapidly increased in number, and when 

 the great majority were in this state, stimulation of the nerve had no longer 

 an effect. At a later stage, up to six days, no staining of the nerve endings 

 was obtained, but at times there was a faint staining of the sole. Huber, 

 however, lays no great stress on this result, since the staining in the normal 

 condition was uncertain. At a still later stage (about 30 to 178 days), 

 i.e., when time was allowed for regeneration, nerve endings were again 

 obtained. 



The only gap in these observations is that the intermediate forms between 

 the first stage of granular ■ degeneration and absorption are not described. 

 They show definitely that in mammals the nerve ending alters rapidly on 

 nerve section, losing its normal staining power with methylene blue, and 

 it may fairly be inferred that the nerve ending, like the axis cylinder, 

 degenerates. 



In order to form an independent opinion on the question, I have made some 

 observations on the nerve endings of the frog by the methylene blue method. 

 In the sartorius muscle of the frog a considerable number of nerve endings 

 can with certainty be shown by methylene blue ; I have not had one failure 

 in more than a hundred trials. I have cut on one side, under anaesthetics, the 

 branch of the sciatic (n. descendens communis) which supplies the sartorius 

 muscle, and a variable time after the section, killed the frog, taken the 

 sartorius muscle of the cut and uncut side and treated them in the same 

 way in methylene blue. I find that about three weeks after section of the 

 nerve, the nerve endings show deep stained small granules in a faintly 

 stained basis, that later the granules became smaller and fewer, and the basis 

 barely visible. About six weeks after section, no trace of nerve endings is to 

 be seen. A semi-diagrammatic sketch of one of the granular nerve endings 

 I give in fig. 6. 



* Huber, 'Amer. Journ. of Physiol.,' vol. 3, p. 339, 1900. 



