REGENERATION IN HYDRA ATTENUATA 



581 



tion similarly implies that at the time of budding, a given amount of material 

 exists in the mother animal which is insufficient to fully support another morpho- 

 genetic occurrence, and that consequently thèse occurrences would in some way 

 be either déficient or slower. The following experiments were performed in order 

 to investigate the effect of the présence of a bud on hydranth régénération at 

 various axial levels. 

 HOURS 



AXIAL 



JBT 75% 50% 25% 10% JAB LEVEL 



Fig. 6. 



Basai plate and tentacle differentiation times. The mean BDT's and TDT's of the weighted 

 four clone means at the given axial levels. (BDT= Basai Plate Differentiation Time, 

 TDT=Tentacle Differentiation Time, JBT= Just Below Tentacles, JAB= Just Above Basai 

 Plate. The Connecting Unes are intended only to show that the déclines are not steady). 



(b) Materials and Methods 



1. Régénération at the various levels of budding and non-budding "Standard" 



animais 



Occasionally, if by chance the mothers of standard animais (see page 568) 

 have been very well fed, the standard animais make buds in the 24 hours during the 

 time between their detachment from their parent animais and the time of cutting. 

 Because this occurrence is irregular and since no différence in the régénération 

 performance was found among the four clones (see preceding section) at any of 

 the given levels, the controls for this experiment are considered those standard 

 animais in a given experiment which did not produce buds and the data of ail 

 controls and of ail budding animais are respectively pooled for statistical considéra- 

 tion. Standard budding and non-budding animais, then, were eut at JBT, at 75 % 



