ALLISON L. BURNETT 429 



cell to cell since there was a direct connection between the head and 

 gastric regions through the gastrovascular cavity. 



Another series of experiments were undertaken to determine 

 why the inhibitive principle is not effective in the budding region 

 of the animal, and whether the inhibitive principle affects the divid- 

 ing cells in the hypostomal region where it is produced. 



It appeared possible that as the inhibitive principle diffused 

 proximally along the gastric region that it might become more 

 dilute or perhaps inactivated or broken down after it remained for a 

 given period of time in the gastric region. If this hypothesis is cor- 

 rect, then it should be possible to suppress the asexual reproductive 

 process by placing the growth region closer to the budding region 

 than it is normally. 



It was shown that if the gastric region of the hydra is removed, 

 and the growth region grafted to the area adjacent to the budding 

 region, budding will not occur until growth process in the hypo- 

 stomal region have forced the "head" some distance away from the 

 budding region. This distance is roughly porportional to the area 

 occupied by the excised gastric region. However, it was also shown 

 that if the head is transferred to a site adjacent to a budding region 

 which has already begun bud formation, the bud goes on to form 

 normally and is not inhibited by the transplanted head. 



These experiments suggest that once a region is actively in- 

 volved in growth processes it is not influenced by the growth in- 

 hibitive principle. This observation explains why the inhibitive 

 principle is not effective in the area in which it is produced. It 

 exerts its effect only on those cells which have been pushed proxi- 

 mally because of growth processes in the hypostomal region. How- 

 ever, these experiments also indicate that budding can be sup- 

 pressed by the presence of a hypostomal region in the immediate 

 vicinity if cell division which would eventually lead to the formation 

 of a bud has not begun. 



In view of these results it appears that once active cell divi- 

 sion in the budding region begins this region is similar to the hy- 

 postomal growth region of the parent. Neither of these two regions 

 are influenced by the inhibitive principle; both are, in a sense, form- 

 ing an entirely new individual. Perhaps this analogy can be further 

 extended, and it may be hypothesized tliat the developing bud 



