PHYISOLOGICAL BASIS OF PATTERN 45 



so far as examined, the region of greatest physiological 

 activity as indicated by other methods showing in 

 general the highest electronegativity through the gal- 

 vanometer. These data are not yet published. Obser- 

 vations along these lines have been made by Mathews 

 (1903) on hydroids, Waller (1903) on various organisms, 

 and Hyde (1904) on certain vertebrate embryos, and 

 both Mathews and Waller point out the probable relation 

 between electric potential and physiological or metabolic 

 activity. Morgan and Dimon (1904) in a study of 

 electric potential in the earth\vorm found that in general 

 the two ends were electronegative to middle regions and 

 concluded that the potential differences were not related 

 to physiological polarity. We know now, however, 

 that the earthworm and other annelids develop very 

 early a growing region of high physiological activity at 

 the posterior end (Hyman, 1916; Child, 1917^) 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. More 

 recently Tashiro (1917 and earlier papers) on the basis 

 of his work on CO 2 production in the nerve fiber has 

 pointed out the probable relations between the electric 

 phenomena and metabolic activity in nerve, and Hyman 

 (1918) has also suggested that bioelectric phenomena in 

 general are primarily due to differences in metabolic 

 activity. While differences in potential undoubtedly 

 may arise in organisms from other causes than differ- 

 ences in metabolic or oxidation rate the facts in general 

 indicate that such differences are at least very gener- 

 ally associated with differences in metabolic rate. In 

 any case the axial gradients in potential indicate the 



