THEORY OP THE BREAK-CONTRACTION. 73 



than the nerve-current. That this is actually the case may be seen 

 from Griitzner's experiments, p. 163. 



Griitzner further found that in the lower part of the sciatic nerve 

 of the frog an ascending- nerve-current exists. When therefore this 

 part of the nerve is stimulated, the ascending break-contraction 

 must show itself later than the descending, since in the latter case 

 the nerve-current is added to the polarisation-current, while, in the 

 first case, the two currents flow in opposite directions. At this 

 result Griitzner arrived experimentally. He stimulated the lowest 

 part of the nerve and found a descending break -contraction 

 when the rheochord slider stood at distances of 60, 45, and 690 mm , 

 while he obtained an ascending break-contraction in the first case 

 with a distance of 36o mm , and in the two other instances failed to find 

 it when the slider stood at jooo mm (see 1. c. p. 164). Just as, when 

 the nerve was excited in the neighbourhood of the cut end, where 

 of course the nerve-current is descending, so he found that on 

 exciting the nerve in the neighbourhood of the muscle, where the 

 nerve-current is ascending, there was a gap in the series of opening 

 contractions (see p. 173). 



Where the nerve is free from any current, i. e. at its middle, no 

 difference is to be expected in the strength of current necessary for 

 the appearance of make- and break-contractions respectively, 

 whatever may be the direction of the stimulating current. That 

 this is actually the case is proved by Griitzner's experiments 

 (p. 164, 165). 



The results found by Griitzner are therefore not at variance with 

 my theory of the break-contraction, but rather furnish new proofs 

 of its correctness. Moreover, they afford indications of a new 

 cause of the break-contraction under certain conditions, which has 

 hitherto received from enquirers only a cursory attention. In proving 

 more thoroughly than has before been done that the nerve-current 

 is sometimes of sufficient strength to liberate a contraction, his 

 results have supplied an additional support to my theory, since they 

 have once more shown of how little consequence for the appearance 

 of a contraction is the absolute strength of the current in com- 

 parison with several other circumstances, such as the abruptness of 

 the increase of current strength, the condition of excitability, and 

 so on. 



I have already mentioned that some facts discovered by Bieder- 

 mann agree very closely with my theory. His paper gives, besides, 

 a number of new results which are in great measure explained by 



