MEMBRANE CHANGES DURING STIMULATION 343 



phase of the bioelectric variation in frog's voluntary 

 muscle), and that of this period one-third (i o") is occupied 

 by the initial chemical decomposition (CaoO? with 

 Qio = 3, and the remaining two-thirds (20-) by a physical 

 disintegration (PaoOj with Qio=i.3 (the temperature- 

 coefficient of diffusion processes). Then: (i) Total 

 duration of breakdown at 20°, C2o°+P2o° = 3 o") (2) total 

 duration of breakdown at 10°, Cio°+Pio°=i crX3 + 2 cX 



1.3 = 5.60-. The ratio — — , is 1.9, the Qio for the total 



o 



process. 



This value is similar to those obtained by a number 

 of investigators (Maxwell, Lucas, WooUey, Snyder, and 

 Harvey)' for the transmission-process in nerve and 

 muscle. The recovery-process, on the other hand, 

 which apparently occupies the greater part of the 

 refractory period, presumably depends chiefly upon the 

 reconstruction of the surface-film by metabolic synthesis, 

 and accordingly exhibits the high temperature-coefficient 

 characteristic of chemical processes. 



The general theory of the refractory period is thus 

 closely related to that of the stimulation-process as a 

 whole. If stimulation is in fact dependent on an al- 

 ternate breakdown and reconstruction of the surface- 

 films of the irritable elements, we should expect irritability 

 (which depends on the state of the film) to vary during 

 the successive stages of the stimulation-process in a 

 manner very similar to that which we observe. 

 Evidently there are two distinct processes involved in 

 the local change of stimulation, corresponding respec- 

 tively to the ' ' absolute ' ' and the ' ' relative ' ' periods. The 



' Loc. cit 



