Physiology. — '^On the refractory stacje of the frog's gastrocnemius''. 

 By Miss L. Kaiser. (Communicated by Prof. G. van Rijnberk). 



(Communicated in the meeting of Jan. 26, 1918) 



The values ^iven for the length of the refractory stage — the 

 short time following upon an ultra maximum stimulus, during which 

 a new stimulation has no eflect — are widely different. 



As a rule the time of the refractory stage is considered equal to 

 that of the latent period for which Tigerstedt ^) by a great number 

 of experiments found an average of 0.005". Tigerstedt likewise 

 found that this value was affected by changes relating to the 

 temj)erature, the kind of stimulus, its strength, the tension or to 

 the mass to be moved. According to Waller*) fatigue lengthens the 

 latent period. 



Helmholtz"), determining the length of the refractory stage itself 

 arrived at ^o' (tbat is about 0.0016"), Kronecker and Stanley Hat,l*) 

 at yfj" (about 0.007") and sometimes y^,," (about 0.0032"), and 

 Samjloff ') at 0.002". 



As regards the effect of various circumstances on the length of 

 the refractory stage I could find no data. Schenck *) saw that fatigue 

 and Ishihara ') that refrigeration were unfavourable to the summa- 

 tion, which is of course stronger in proportion as the second stimulus 

 reaches the muscle at a moment when it is able to show distinctly 

 that it is stimulated. 



To determine whether the length of the refractory stage is influenced 

 by various circumstances and if so, in what direction and to what 

 extent, the following experiments were made. 



1) Archiv. f. Physiologie 1885 Supplement. 



2) LuGiANi. Physiologie des Menschen III. 



3) Yerhandl. der Kön. Preuss. Akademie 1854. 

 *) Archiv. f. Physiologie 1879 Supplement. 



») Pfl. Archiv. Bd. 143. 

 «) Pfl. Archiv. Bd. 96. 

 7) Pfl. Archiv. Bd. 111. 



