242 THE BIOLOGY OF HYDRA : 1961 



KLINE: When you maintain the Hydra on heat killed Artemia, 

 does the growth rate remain constant, even if reduced? 



CLAYBROOK'. Fairly constant. It varies slightly with the various 

 lots of shrimp. 



KLINE: Then you didn't totally destroy something that is needed. 

 Perhaps you reduced its concentration. How did you interpret the 

 results? 



CLAYBROOK: The growth factor is not completely destroyed, 

 but becomes limiting to growth. 



KLINE: In one experiment you had heat precipitated material 

 on which the Hydra were able to grow quite well. 



CLAYBROOK: Right. This is the liver extract. We have not 

 fractionated shrimp because the relative supply of liver and shrimp 

 are not the same. 



LENHOFF: Is it possible that the more you heat the shrimp, 

 the more the shrimp's cellular integiity is destroyed? And when 

 you put these damaged shrimp in water, essential factors leak out? 

 A few years ago Dr. Loomis and I were able to grow Hydra 

 on frozen shrimp, but had no success with boiled shrimp. We 

 thought then that boiling either destroyed a heat labile factor or 

 allowed essential heat-stable factors to leak out. 



CLAYBROOK: It is possible, but in a few experiments we 

 found no activity in the supernatant that the shrimp were boiled 

 in. I wouldn't say this was conclusive. 



LENHOFF: Was this supernatant solution either ninhydrin or 

 protein-positive? 



CLAYBROOK: We didn't check at this stage but I'm sure that 

 there were ninhydrin-positive components there. 



GOREAU: What I am speculating on now assumes a nervous 

 system! Living AHemia may be required because the struggle with 

 the prey could set up a reflex which causes hydra to secrete 

 enzymes or produce preabsorptive changes in the gastroderm, 

 which would allow digestion to proceed in a much more complete 



