PHYSICO-CHEMICAL BASIS OF TRANSMISSION 399 



ently this general condition is illustrated in the phe- 

 nomena of growth and development. There is evidence 

 that many cases of form-correlation in both plants and 

 animals have an electrical basis. Actively growing 

 regions of organisms have usually been found electrically 

 negative to more slowly growing regions. Hermann and 

 Miiller-Hettlingen' observed that in seedlings the 

 regions near the growing zones (terminal buds and root- 

 tips) were negative to those near the cotyledons; similarly 

 the growing zones of planarians and annelids are negative 

 to intermediate regions,^ and in hydroids regenerating 

 hydranth heads are negative to the stems.^ In general 

 the indications are that regions of active constructive 

 metabolism — which are usually regions of active oxidation 

 — are typically negative to less active regions. Miss 

 Hyde's observations on fish eggs'* indicate that during 

 cell-division the cell body undergoes a temporary 

 negative variation, analogous to that accompanying 

 excitation; the electrical negativity of regions in active 

 proliferation may thus be accounted for. 



The presence of bioelectric circuits between the 

 rapidly growing regions of an organism and the regions 

 adjoining is in all probability an important if not the 

 chief factor in the controlling influence (''physiological 

 dominance") which the former exerts upon the latter. 

 In plants it has long been known that the removal of 



» Hermann, Arch. ges. Physiol., XXVII (1882), 288; Miiller- 

 Hettlingen, ibid., XXXI (1883), i93- 



*Cf. Child, Biological Bulletin, XLI (192 1), 90; Hyman and 

 Bellamy, ibid., XLIII (1922), 313. 



3 Mathews, American Journal of Physiology, VIII (1903), 294; 

 Lund, Journal of Experimental Zoology, XXXVI (1922), 477. 



4 1. H. Hyde, American Journal of Physiology, XI (1904), 52. 



