o 



80 AVERS. [Vol. VIII. 



important in that they make it possible to institute some 

 comparisons between the highly differentiated mammalian 

 larynx and the much simpler amphibian organ which we 

 have every right to expect will show us the primitive mode 

 of action of this specialized set of muscles, and in this way 

 throw some light on the points still to be elucidated. 



The question of the influence of the rate of stimulation on 

 the action of nerves is the outgrowth of attempts to explain 

 a much older question — the so-called Ritter-Rollet phe- 

 nomenon. Ritter discovered, and later on Rollet^ established 

 more firmly, that (i) when the sciatic nerve of a frog is acted 

 on by a zveak tetanic electrical stimulation the flexor group 

 of muscles contract, producing flexion of the leg and adduction 

 of the toes, and that (2) when such a stimulus of greater 

 strength is applied to the nerve the extensor group of muscles 

 contracted producing extension of the leg and abduction of the 

 toes. Since then it has been shown that the same is true of 

 other vertebrates, including mammals. Experiments on in- 

 vertebrates show that this peculiar difference between the 

 antagonistic muscles of the appendages must lie in a funda- 

 mental quality of nerve-muscle mechanisms, for the Lobster's 

 claw has been found to open in response to the stimulation 

 of weak electrical currents, while closing upon increasing the 

 strength of the stimulus. It has been usual to account for 

 these phenomena by the hypothesis of ^^ differing irritabilities.^^ 

 Fick and Bour, however, explained the phenomena on the basis 

 of the differences in the length, thickness and position of the 

 antagonistic groups of muscles. Wedensky, on the other hand, 

 thought it could be accounted for on the basis of the rate or 

 frequency of stimulation. His experiments with the aid of the 

 telephone show, ist, that with indirect tetanus of the muscles, 

 it often happens that the muscle does not contract upon the 

 application of the proper stimulus, but only in response to low 

 rates, and 2d, that any variation of the intensity of the stimulus 

 is, in a certain sense, equivalent to a similar variation of the 

 rate, for indirectly tetanized muscles, so that the same result 



1 4. Sitzber. d. Wiener Akad. Bd. LXX bis LXXII. jte Abth. Richet and 

 Luchsingers. 



