1 66 C. M. CHILD. 



gastrulse. This reaction is an oxidation which is catalyzed by 

 oxidizing enzymes and which results in the formation of indo- 

 phenol in the form of a blue precipitate. In living starfish blas- 

 tulse and gastrube (Child, J i5a) a distinct apico-basal color gra- 

 dient has been observed by this means, the formation of indo- 

 phenol occurring most rapidly in the cells of the apical region. 

 If the animals are killed by some other agent before the indo- 

 phenol reaction the blue color is much less marked and the gra- 

 dient is absent. 



Gradients in Electric Potential. Axial gradients in electric 

 potential have been found by Drs. Bellamy and Hyman to exist 

 in axiate animals so far as examined, the region of greatest 

 physiological activity as indicated by other methods showing in 

 general the highest electro-negativity through the galvanometer. 

 These data are not yet published. Observations along these lines 

 were first made by Mathews ('03) on hydroids, Waller ('03) on 

 many different organisms and organs and Hyde ('04) on various 

 eggs, and both Mathews and Waller point out the probable rela- 

 tion between electric potential and physiological or metabolic 

 activity. Morgan and Dimon ('04) in a study of electric poten- 

 tial in the earthworm found that in general the two ends were 

 electro-negative to middle regions and concluded that the poten- 

 tial differences were not related to physiological polarity. We 

 know now, however, that the earthworm and other annelids de- 

 velop very early a growing region of high physiological activity 

 at the posterior end (Hyman, '16; Child, '17^) and that the body 

 in later stages shows two gradients in opposite directions. The 

 observations of Morgan and Dimon do not therefore conflict 

 with those of others on other animals. More recently Tashiro 

 ('17 and earlier papers) on the basis of his work on CO 2 pro- 

 duction in the nerve fiber has pointed out the probable relations 

 between the electric phenomena and metabolic activity in nerve, 

 and Hyman ('18) has also suggested that bioelectric phenomena 

 in general are primarily due to differences in metabolic activity. 

 While differences in potential undoubtedly may arise in organ- 

 isms from other causes than differences in metabolism or oxida- 

 tion rate the facts in general indicate that such differences are 

 very generally associated with differences in metabolic rate. In 



