THEORY OF AXIAL GRADIENTS 



267 



TABLE 1 

 Time in hours required for emergence of the oral hydrants of two pieces of equal length 



The experiments were carried out at New York (with material 

 from Long Island Sound and from the Lower Bay) and at Woods 

 Hole, and the results were similar in both places. The material 

 and conditions, especially at Woods Hole, were so excellent that 

 we were able to keep the regenerating stems alive in finger bowls 

 for more than fifteen days. 



In each case we recorded the time of emergence of the hydranth 

 outside the perisarc, and observations were made at least every 

 two hours. 



In the first group of experiments (table 1), the stems were cut 

 into two pieces of equal length; several series of this type, with 

 twenty stems each were made with similar results, namely, 

 that there is no marked difference between the times of appearance 

 of the oral hydranths of the two pieces. Very often the oral hy- 

 dranth of the basal piece is the first to appear. As an example of 



