3i6 PROTOPLASJVaC ACTION AND NERVOUS ACTION 



of plants (Mimosa, Venus' fly-trap), and growth pro- 

 cesses; they are probably also associated with cell- 

 division and ciliary movement. 



They appear in fact to be as essential a feature of 

 protoplasmic action as the consumption of oxygen or the 

 evolution of CO2. The fact that their rate of develop- 

 ment and their rhythm are influenced by changes of 

 temperature in the manner characteristic of chemical 

 reactions (Qio = 2-3)^ indicates their dependence upon 

 the fundamental metabolic processes of protoplasm. 

 Direct proof that the bioelectric rhythms are accompanied 

 by rhythmical chemical reactions is at present lacking, 

 but there are many indications that this is the case. 

 The evidence is clearest in those instances where the 

 rhythm is slow. Thus the production of CO2 by dividing 

 sea-urchin eggs follows a rhythm which runs parallel with 

 the rhythm of cleavage;^ the latter rhythm is accom- 

 panied by a parallel rhythm of variation in the physical 

 properties of the egg surface;^ and this rhythm is almost 

 certainly associated with a variation of potential."* 

 In a certain sense it is self-evident that the energy of 

 the bioelectric currents, as of other organic activities, 

 represents the transformed energy of chemical reactions; 



* Cf. Piper's results on tortoise muscle {Elektrophysiologie mensch- 

 licher Muskeln, Berlin [1911], chap, ix, 130). Cf. also the data in Gar- 

 ten's article, loc. ciL; also Lucas, Journal of Physiology, XXXIX (1909), 

 207. 



' E. P. Lyon, American Journal oj Physiology, XI (1904), 52; Science, 

 XIX (1904), 350. 



3 Cf . my paper on the physiology of cell-division in the Journal of 

 Experimental Zoology, XXI (191 6), 369. 



< This is indicated by Miss Hyde's observations in the Fundulus 

 e?g, American Journal of Physiology, XII (1904), 241. 



