MEMBRANE CHANGES DURING STLMl'LATIOX 341 



lack of oxygen, and partial ana'sthcsia, at least in some 

 cases;' but in nerve Lucas found the rate uf rccoverv 

 to be normal in solutions of alcohol sufficient to p^reatly 

 retard transmission.^ Bazett observed an inlluencc of 

 the salts of the medium, increase of potassium lengthen- 

 ing, and increase of calcium shortening the interval.-* 

 Various poisons such as veratrine, muscarine, digitalis, 

 and barium salts also lengthen the refractory period.'* 



The temperature-coefficient appears to be high in all 

 cases. In frog's muscle and nerve Bazett and Adrian 

 obtained Qio values of three or more.^ Burdon-Sanderson's 

 observations on the frog's heart indicate values ranging 

 from 2 to 2.5.^ The fact that the process of recovery 

 shows this high coefficient seems to indicate its depend- 

 ence upon processes of constructive metabolism: the 

 temperature-coefficients are in fact similar to those of 

 growth processes. 



It is interesting to note that the various forms of 

 protoplasmic transmission (in nerve, muscle, etc.), 

 which theoretically depend on processes of breakdown, 

 have usually shown temperature-coefficients of a tlis- 



^Cf. Verworn, AUg. Physiol., 4th ed., Jena (1903), p. 559; 

 Irritability, Yale University Press, 1913, chap, xii; FrOhlich, Z. allg. 

 Physiol., Ill (1904), 468. 



'Journal of Physiology, XL VI (i9i3)> 470- 



3 Bazett, Journal of Physiology, XXXVI (1908), 414. 



4 Cf. Tait, loc. cil.; Trendelenburg, loc. cit.; dc Boor, Jourtuil of 

 Physiology, XLIX (1915), 312; American Journal of Physiology, XLVII 

 (1921), 179, 189. 



5 Cf. Bazett, loc. cit.; Adrian (1914), and (192 0, loc. cit. 



6 Eckstein {Arch. ges. Physiol, CLXXXIII [1920], 40) finds a 

 value of 2.6 for the refractory period of frogs' ventricle (average of 10 

 experiments between 5° and 20°). 



