THE AXIAL GRADIENTS IN HYDROZOA. 397 



pieces indicates very clearly that the apical pieces have a higher 

 rate of chemical activity. They are more affected by the de- 

 pressing agents and more retarded. 



5. The Effect of Cutting the Distal End of the Apical Piece at the 

 Base of the Hydranth. When questioned regarding his manner 

 of cutting the pieces for his experiments, Banus replied as follows 

 (I quote verbatim from his letter): "The most distal cut was 

 usually made as near as possible to the hydranth without includ- 

 ing any part of it. Other times more basal parts were used. 

 No difference in the results was found." To two subsequent 

 letter* requesting more specific statements concerning this matter 

 and asking for a diagram showing the exact relation of the most 

 distal cut to the base of the hydranth, Banus returned no replies. 

 The first sentence quoted leaves little doubt that Banus made his 

 most distal cut just below the base of the hydranth, therefore 

 including in the apical pieces, the little neck or stalk region of 

 the hydranths. The rest of Banus's statement is too vague to 

 merit any attention. What is meant by "more basal parts"? 

 How is one to know in the experiments reported by Banus in 

 which cases the distal cut was made at the base of the hydranth, 

 and in which cases more basally? Certain it is that in some of 

 Banus's pairs of pieces the apical piece emerges first, and in 

 others the basal piece. This indicates some great irregularity in 

 his method of procedure. Probably those cases where the apical 

 pieces emerged first are the ones in which "more basal parts 

 were used." In the absence of more definite information, specu- 

 lation is idle. We are here concerned with the fact that usually 

 the distal cut was made at the base of the hydranth. 



I have performed three experiments in which the apical pieces 

 were cut in the manner usually employed by Banus and as 

 represented in text-figure 5. Such apical pieces include the 

 stalk of the hydranth. This stalk is incapable of regeneration. 

 It together with that portion of the coenosarc which occupies the 

 distal end of the perisarc dies away and disintegrates. This 

 process of death and disintegration of the apical end of apical 

 pieces cut in this manner naturally delays the regeneration of the 

 apical pieces, because regeneration does not begin until the end 

 of the piece has rounded off and become covered with a layer of 



