STRUCTURES RESEMBLING ORGANIC GROWTHS. 185 



There is no doubt that the distinctive vital properties of 

 self-maintenance, growth, and reproduction are closely inter- 

 connected; it would probably be more correct to say that they 

 are manifestations of the same fundamental physiological activity 

 under somewhat different conditions. The essential feature of 

 this activity is constructive metabolism of a specific kind. The 

 mechanism determining this process of construction must be 

 intimately connected with the mechanism determining the re- 

 sponse to stimulation, since stimulation, which effects a break- 

 down of the living substance, must itself form the condition 

 of the restitution of the broken-down material, if the system 

 is to continue to exist. This was clearly recognized by Claude 

 Bernard. 1 Some kind of self-regulating cycle, in which a destruc- 

 tive process calls forth automatically or inevitably a counter- 

 process of repair, would thus seem to be the necessary foundation 

 of any form of vitality. An analogy to this condition is seen in 

 the chemical processes of any electrolytic circuit; just as oxida- 

 tion at the one electrode involves the inverse process at the other 

 electrode, so decomposition or structural breakdown at one 

 region of the cell-surface may, by giving rise to a local bioelectric 

 circuit, directly determine a reparative synthesis either at the 

 same or at an adjoining region. 2 Some general physico-chemical 

 condition of a simple kind must be common to all of the various 

 types of living system, since they are all living. The universality 

 of the cellular type of organization seems to my mind at least 

 -to indicate that the essential structural condition in living mat- 

 ter is the presence of polarizable partitions at which processes of 

 electrolysis, including both syntheses and decompositions, are 

 to be conceived as taking place under the influence of local 

 electrical circuits. The self-maintaining character of the living 

 system, its responsiveness to outside influence (especially of an 

 electrical kind), and the transmission of chemical influence to a 

 distance, become to a considerable degree intelligible on such an 

 hypothesis. These considerations may appear too speculative 

 to many ; but further advance in physiological analysis seems to 

 demand that the fundamental vital processes should at least be 



1 Cf. e. g., "Legons sur les phenomenes de la vie," Vol. i, p. 127. 



2 For further discussion of this possibility cf. my recent paper, Amer. Journ. 

 Physiol., 1917, Vol. 43, pp. 56, 57. 



