CHAPTER XIII 



BIOELECTRIC PIIEXOMKXA 



A complete review of this large field of research is not 

 possible in the space at our disposal.' It is necessary, 

 however, to consider in some detail the chief facts 

 bearing on the present problem; these may be con- 

 veniently grouped under the two headings: (i) bio- 

 electric potentials in resting cells and tissues; and (2) 

 variations of bioelectric potentials in relation to physi- 

 ological activity. 



RESTING BIOELECTRIC POTENTIALS 



The existence of potential-differences between the 

 resting cell or other protoplasmic element and its sur- 

 roundings has in itself nothing unexampled or surprising. 

 Typically such potentials are found at all phase- 

 boundaries unless special compensating conditions are 

 present. The conditions on either side of the interface 

 are asymmetric with respect to chemical composition 

 and physical condition, and corresponding to this 

 assymmetry there is an electrical asymmetry or potential- 

 difference. The facts of electrical convection and 

 electrical endosmose show the presence of potential- 

 differences between all kinds of insoluble mjjtcrials 

 and the adjacent layer of solution. These potentials 



^ For an exhaustive account of the earlier work, cf. Bictlormann's 

 Electrophysiologie, English translation. For a more recent account, 

 cf. Bernstein's Elcdrobiolflgic (1912), and the article of (iartcn, "Trotiuk- 

 tion von Elektrizitiit," in Wintcrstein's Handbuch dcr vcrgl. Physiol., 

 Ill (1910), 105; also the interesting but more sj^ecial work of Bosc, 

 Comparative Electro physiology (1907). 



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