94 PROTOPLASMIC ACTION AND NERVOUS ACTION 



response to an extremely slight rise of acidity due to 

 increase in the CO2 of the blood. 



ELECTRICAL ENDOSMOSE 



Certain physical phenomena of great biological 

 interest, having similar relations to the charged char- 

 acter of the interphasic surfaces, are those classed as 

 electrical endosmose. The essential phenomenon is 

 the transfer of fluids with or against an electric current 

 traversing a porous partition immersed in an electrolyte 

 solution. The fundamental conditions of this transport 

 are the same as those determining the electrical con- 

 vection of colloidal particles or emulsion droplets, 

 except that in electrical endosmose the continuous fluid 

 phase is the mobile one, the solid phase which forms 

 the substance of the partition being fixed in position. 

 Colloidal gels interposed in the path of a current exhibit 

 this phenomenon, and it is well known in protoplasmic 

 systems.^ There is no question but that effects of the 

 same kind must occur normally in living matter, since 

 the latter, during functional activity at least, is continu- 

 ally being traversed by the currents of the bioelectric 

 circuits; and it seems probable that electrical endosmose 

 plays a special role in the processes of secretion and 

 adsorption, as suggested by various physiologists.'' 



^ For example, Hermann describes experiments showing the trans- 

 port of water through tissues (muscle and nerves) in the direction of 

 the positive stream when a constant current is passed through the 

 tissue {Arch. ges. Physiol., LXVII [1897], 240). 



^Engehnann, Arch. ges. Physiol., VI (1872), 97; Waymouth Reid, 

 Phil. Trans., Series B, CXCII (1900), 239; Hober, Arch. ges. Physiol, 

 CI (1904), 607; cf, also my recent paper in Biological Bulletin, XXXIII 

 (1917), 135, i7off. 



