408 



THE BIOLOGY OF HYDRA : 1961 



these screening tests were made, was the fact that we were unable 

 to determine the extent to which the agents being tested were 

 actually absorbed into the hydra cells. 



TENTACLE NUMBER 

 ALTERATION 



DLCREASL 



(5-Eromuracil) 



INCREASE 



(Lithium chloride) 



INHIBITION OF 

 REGENERATION 



Lithium chloride 



Chloretone 



5 " Bromurac il 



"2 Thienyl alanine 



TIME IN HOURS 

 Fig. 1. Periods of sensitivity of hydro to regeneration-altering agents 



The micro-injection technique perfected by Dr. Claybrook now 

 makes it possible for us to introduce these inhibitors, metabolites, 

 and drugs into the enteron in semi-solid agar where they will 

 certainly be absorbed to a much greater degree than they would be 

 from the environmental culture fluid. We are currently re-examining 

 the effects of these agents with the refinements in our experi- 

 mental techniques that we have developed since the initial chemi- 

 cal studies were made. 



One of the most unique effects disclosed by the study of chemi- 

 cal agents was that encountered when one of the more recently 

 discovered members of the B vitamin complex — lipoic acid — 



