186 THE BIOLOGY OF HYDRA : 1961 



the animal that possesses them? The independent effector is quite 

 different from the effector at the end of a wasp; it is not so neatly 

 controlled. The tentacle of a coelenterate coils around its prey. 

 There is a great chance for nematocysts to be discharged into a 

 tentacle. This would obviously create difficulties if the tentacle was 

 paralyzed by its own poison. 



BURNETT: It is common for hydra to pierce its own tissues 

 with nematocysts during feeding. 



PHILLIPS: I think the experiments of Dr. Ross, and of Dr. 

 Martin and the ones that I did on Metridium suggest that caution 

 should be employed in the interpretation of work using whole 

 tissue extracts. Sometime ago, when I was working on the toxin, 

 I detected a 5-hydroxyindole compound, which at that time I 

 thought corresponded more closely to bufotenin. On purification 

 I noticed that the level of 5-hydroxyindole compounds decreased 

 steadily. In fact, pure suspensions of nematocysts contained no 

 detectable 5-hydroxyindole compounds at all, yet the nematocysts 

 were still capable of discharging and still possessed toxicity. 



WELSH: In that connection, I would be interested to know if the 

 5-hydroxytryptamine washed out of the nematocyst. It's a small, 

 soluble molecule that diffuses readily through some cell surfaces. 



PHILLIPS: This is a possibility. But the nematocyst suspensions 

 after purification still should show toxicity. 



WELSH: I don't think that the serotonin is really toxic. You 

 can put a large amount of serotonin into a crab and it gets very 

 nervous and jittery. An hour later it is normal. 



PHILLIPS: Diffusion from the nematocyst during purification, of 

 course, is always a possibility. At the same time, nematocysts are 

 still susceptible to osmotic discharge, so that gross permeability 

 changes do not seem to have occurred. 



LOOMIS: How do you keep your nematocysts from discharging 

 while you separate them? 



PHILLIPS: With high concentrations of sucrose. 



