JOHN H. WELSH 181 



in such a manner as to block conduction and or transmission 

 ( 17 ) . The neutrahzing action of certain acetylchohne blockers such 

 as tetraethylammonium (TEA) on the paralyzing action of ten- 

 tacle extracts supports this view (25). 



Certain of the symptoms that follow a coelenterate sting such 

 as pain, burning, itching, localized edema and hemorrhaging 

 could result from injected 5-HT (a potent pain producer and his- 

 tamine releaser), from histamine itself, and from other histamine 

 releasers. These sul^stances, however, cannot be responsible for 

 the paralyzing action of the nematocyst contents. Many quaternary 

 ammonium compounds do have a paralyzing action as junctional 

 blocking agents. Of those listed above, only tetramine can qualify 

 as a candidate for the paralyzing action. In the first place it is the 

 only one that has been identified in hydra extracts, while most 

 of the others are widely distributed among the marine invertebrates. 

 In the second place, tetramine is an effective poison and is the 

 toxic component of the salivary glands of certain marine gastropods 

 (7, 9), while the others are surprisingly non-toxic (cf. 27). Fur- 

 thermore, the earlier observed antagonism of coelenterate extracts 

 by tetraethylammonium chloride or Banthine (25) strongly sug- 

 gests that a methylated quaternary nitrogen compound is, in some 

 way, involved in the paralysis resulting from a coelenterate sting. 

 However, calculations may be made that indicate that there is 

 not enough tetramine, in the extracts that we have used, to account 

 for their paralyzing action, at least on arthropods. 



Evidence has been accumulating over the years that the paralyz- 

 ing factor in coelenterate toxins is a protein or group of proteins. 

 Several recent studies show that toxicity remains after dialysis but 

 is destroyed by boiling and by treatment with certain proteolytic 

 enzymes (14, 15, 16, 18). The exact mode of action of the toxic 

 protein ( s ) is not yet clear. 



RfiSUME OF SOME EXPERIMENTS THAT ARE 

 CURRENTLY IN PROGRESS 



We are, at present, comparing the actions of homogenates of 

 Metridium acontia and whole Hydra, and of material discharged 



