PHYSICO-CHEMICAL BASIS OF TRANSMISSION 403 



reactions occurring in the protoplasm; conversely, 

 electric currents passing through protoplasm from with- 

 out alter its activity through their direct influence on its 

 chemical processes. Hering also concludes, from the 

 contrast between the physiological effects at the two 

 electrodes, that where the current enters protoplasm 

 from the surroundings it induces or promotes assimilatory 

 (anaboHc) processes, and where it leaves, dissimilatory 

 (catabolic) processes. In the typical irritable tissue the 

 inhibitory effect at the anode is the expression of a 

 predominance of anabolic processes, while the stimulation 

 at the cathode results from chemical effects of the reverse 

 kind (predominantly catabolic). 



From our present point of view the above-described 

 influences on growth and regeneration point to the conclu- 

 sion that where the current enters the protoplasmic sur- 

 face from the exterior it has the effect of promoting 

 oxidation processes which form secondarily the condition 

 of the syntheses required for the formation of new struc- 

 ture. Growth, repair, and recovery from stimulation are 

 the result or expression of chemical reactions of the same 

 general kind, apparently oxidative syntheses, which occur 

 predominantly at the one polar region. At the other 

 polar region reactions of the reverse kind are promoted; 

 these form the condition for stimulation in irritable 

 tissues or for cessation of growth or degression in growing 

 regions. 



The closest physico-chemical analogies to such 

 processes are furnished by the chemical effects at elec- 

 trodes, i.e., the phenomena of electrolysis; and the possi- 

 bihty that electrolysis may underHe the physiological 

 effects of the electric current was in fact early recognized 



