STRUCTURES RESEMBLING ORGANIC GROWTHS. 179 



of the living cell immersed in its normal medium. The two 

 solutions are to be conceived as differing in their electrolyte- 

 content, so that a potential-difference exists across the membrane. 

 If now we consider a circuit as arising between different regions 

 of the surface in consequence of some local chemical change in 

 the substance of the partition, such as an oxidation, it is clear 

 that the conditions of the flow of current in both solutions must 

 be in principle similar to those just considered; i. e., the mode of 

 current-transport accompanied by chemical change which pre- 

 vails on one side of the interface in the example cited, i. e., in 

 medium E, may equally well prevail on both sides. The essential 

 conditions are that the chemical changes taking place at the 

 interface must be of such a kind as to furnish free energy (for the 

 flow of current), and that the necessary electro-neutrality of 

 either solution is preserved intact. It is not difficult to imagine 

 the general features of such an arrangement, although as regards 

 the special nature of the conditions existing in living cells (the 

 substances involved, the nature of the reactions, etc.) little 

 definite can be said at present. In brief, then, the present con- 

 ception regards the current in the interior of either solution as 

 transported by the movement of ions in the usual manner; but 

 in its transport across the boundary-partition chemical reactions 

 are concerned ; i. e., in this part of the circuit the essential change 

 consists in transfers of electrons between interacting molecules 

 or ions with corresponding chemical reactions which furnish the 

 energy of the current. Such processes would be conditioned in 

 the same essential manner as the processes at metallic electrodes, 

 i. e., would be of the nature of electrolysis, since they would 

 depend upon the flow of the current through the circuit. Hence 

 they would be influenced by electric currents from outside 

 sources, besides giving rise to currents when they occur of their 

 own accord under normal conditions. It seems highly probable 

 that the characteristic electrical properties of living cells depend 

 upon arrangements of essentially this kind; the fundamental 

 general fact that cell-activities both give rise to electrical cur- 

 rents, and are themselves profoundly influenced by currents of 

 outside origin, is most readily understood on this hypothesis. 

 The special nature of the conditions in living cells may now 



