ELECTRICAL AND OTHER FACTORS 251 



compounds which interact with the metal arc not 

 infrequent;' e.g., when the metal is undergoing solution 

 in a strongly oxidizing acid Hke HNO3. Iron in particular 

 often illustrates this phenomenon with great beauty and 

 regularity; in this case the essential condition of the 

 rhythm is an alternation between active and passive 

 states, due, as in the mercury catalysis, to the alternate 

 formation and dissolution of a protective surface-hlm of 

 oxidation-product. All of these inorganic rhythms are 

 highly susceptible to variations in external conditions, 

 and especially to electrical influences. 



The rhythmical processes so frequent in living 

 organisms (rhythms of cilia, muscle, nerve cells, vacuoles, 

 and cell-division) show many close parallels with these 

 inorganic ''surface-reaction" rhythms. As in metals, 

 they are associated with rhythmical variations of electri- 

 cal potential and with rhythms of chemical or metaboUc 

 alteration and surface-change (clearly demonstrable, e.g., 

 in cell-division), and are similarly susceptible to changes 

 in the surrounding conditions (temperature, H-ion 

 concentration, presence of salts and surface-active 

 compounds, electrical polarization, etc.) . These parallels 

 imply a similarity in the essential determining conditions 

 in the living and the non-living systems. Since rhythmi- 

 cal catalysis in metals is dependent on the polyphasic 

 character of the system — tliis being the condition which 

 makes possible rapid local variations of potential, 

 resulting from changes in the composition and structure 

 of surface-films — the hypothesis that the organic rhythms 

 are similarly conditioned naturally suggests itself, 

 particularly when the film-pervaded or emulsion-like 



^ For earlier observations cf. Bredig and Wicnmayr, loc. cU. 



