184 THE BIOLOGY OF HYDRA : 1961 



DISCUSSION 



HAND: The extra serotonin that you find in the acontia seems 

 reasonable in view of some very simple observations that one can 

 make on Metridium and other acontiate anemones. They commonly 

 eat small worms, copepods, and things of this nature. If you get a 

 small transparent anemone, you can see that after the food is swal- 

 lowed the prey is still kicking, wriggling and squirming. It gets into 

 the coelenteron and the acontium coils around the animal, presum- 

 ably the nematocysts of the acontium discharge, and this very 

 quickly subdues it. It quivers a couple of times, and then stops. 

 The acontia, of course, are rich in nematocysts, 



ROSS: Do you think that the amounts of serotonin that you 

 find in the acontia, ca. 1 Mg./g., is significant? Compared with the 

 amounts that we found in other parts of anemones, they seem so 

 small that we would have dismissed them. 



WELSH: Well, I think if I may say so, it was unfortunate that 

 you looked at Calliactis first. I think if you had looked at other 

 anemones you would have viewed this situation differently. 



ROSS: Not at all. 



WELSH: Let me put it this way. If you go out and catch a 

 vicious stinging wasp, you can get out of its venom a perfectly 

 tremendous amount of serotonin. You measure it as 6 to 20 

 milligrams per gram of venom. Now if you do its nervous system, 

 you get a few tenths of a microgram. I believe that the serotonin 

 in the nervous system is just as important in the life of the wasp 

 as the serotonin in its venom. The most we have in any part of 

 our nervous system is 0.4 micrograms per gram of hypothalmus. 

 And if the tranquilizer reserpine is doing what they say its doing, 

 releasing serotonin, then this brings this down to a 10th of that, 

 and here we're working in the lOths and hundredths of micro- 

 grams per gram range. This is less than the concentration range 

 of serotonin that one finds in acontia. 



ROSS: We found 600 times as much in the lining of the coelen- 

 teron in Calliactis, so this made us think it couldn't possibly 

 be associated with nematocyst poisons. 



