ELECTRICAL AND OTHER FACTORS 247 



parallels between this action and the similar action of 

 organic fluids and cell-extracts ha\e Ion*; been known. 

 The decomposition of H^O^ by living tissues is now 

 regarded as due to a special enzyme, catalase. The 

 relation of this catalytic action of tissue-extracts to 

 enzyme action and fermentation was early recognized 

 by Schonbein, who characterized the splitting of U,(), as 

 a model or prototype of all fermentative processes 

 (Urbild alter Gdhrimgen).'- A study of the conditions 

 under which it occurs in the presence of metals may thus 

 throw some Hght on the general nature of catalytic elTects 

 in heterogeneous systems and especially in li\ing proto- 

 plasm. 



Among other metals mercury shows great activity in 

 decomposing H2O2. The most striking feature of the 

 catalytic decomposition of H2O2 in contact with a mercury 

 surface is that under certain conditions the process 

 exhibits a definite regular rhythm, closely resembling 

 physiological rhythms Kke that of the heart beat in its 

 frequency, in its dependence on temperature (Q,o = about 

 2), and in the influence exerted upon it by chemical and 

 electrical conditions. This phenomenon lias lately been 

 the subject of much investigation, specially by Brcdig 

 and his students, and its detailed conditions have been 

 studied most closely by AntropofT.^ The chief result 

 of this study has been to show that the catalytic rhythm 

 is dependent on the alternate formation and dissolution 

 of a surface-film of oxidation-product (''peroxidatc") 

 formed by interaction between the mercury and the 

 peroxide. Since evidence from various sides inch'cates 



» Schoenbein, /. prakl. Cficm., LXXXIX (1863), 335. 

 =» Antropoflf, Z. pliysik. Chem., LXII (1907), S^i- 



