THE AXIAL GRADIENTS IN HYDROZOA. 



have been repeatedly ascertained by several investigators and 

 are totally inexplicable on the point of view maintained by Loeb 

 and Banus that there are no regional differences in the stem of 

 Tubularia. 



There is one further statement made by Banus to which we 

 must take exception. This is the assertion on p. 266 and again 

 on p. 273 that regional differences in rate of regeneration con- 

 stitute the "actual basis" for the axial gradient conception as 



FIG. 5. Method of cutting pieces usually employed by Banus and used for the 



experiments recorded in Table XI. 



applied to Tubularia. They are part of the basis, but not the 

 entire basis, as Banus implies. Axial differences in metabolic 

 rate along the stems of Tubularia had been demonstrated at the 

 time when Banus published his paper by two other methods 

 the differences in susceptibility to potassium cyanide and other 

 substances, and the differences in electric potential. The results 

 yielded by both of these methods are again considered in this 

 paper. 



In view of the fact that Banus's results are in total disagree- 

 ment with a considerable number of researches, a critical examina- 



