THE RANGE OF DOMINANCE 145 



in which no structure is externally visible (Fig. 76). 

 After return to water a new hydranth arises, as in the 

 longer pieces, on the uppermost part (Fig. 77), which 

 represents one side of the basal region of the previously 

 existing hydranths, and the piece undergoes transforma- 

 tion into a new small individual (Fig. 78). In this 

 case the two opposed metabolic gradients which were 

 present at the beginning of the experiment were 

 completely obliterated and a new single gradient 

 arises at right angles, or, if the pieces are not kept 



FIGS. 75-78. Experimental establishment of a new major axis 

 in a piece of Corymorpha which has already formed a biaxial structure: 

 Fig. 75, the biaxial hydranths developed from the piece; Fig. 76, the 

 same piece after reduction in alcohol; Fig. 77, appearance of new 

 hydranth after return to water; Fig. 78, fully developed new individual. 



in the same position throughout, in any relation to 

 the original gradients as determined by the external 

 conditions. 



My experiments along this line were interrupted 

 and no opportunity to continue them has as yet arisen. 

 I believe, however, that the new metabolic gradient in 

 these pieces is primarily determined by the difference in 

 oxygen supply between the free upper surface and the 

 surface in contact, the region of highest rate represent- 

 ing the region of greatest oxygen supply; but further 

 experiment is necessary to determine positively whether 



