On the nature and action of coelcnterate toxins 289 



heterochelos (Lamarck), U. leptodactyla Ralhbun and U. mordax (Smith))* showed 

 v. mordax to be most suitable. In all experiments to be reported here, this species 

 was used. 



Tentacle extracts were prepared from Physa/ia, the Portuguese-man-of-war, and 

 from two common sea anemones, Condylactis gigantea and Aipiasia sp. The extracts 

 were prepared by grinding a known volume of tentacles with an equivalent volume 

 of sea water, either with or without the addition of enough hydrochloric acid to make 

 the suspension weakly acid to litmus paper. If necessary, after filtration the pH was 

 adjusted with NaHCOj until the solution was neutral. Extracts were diluted as 

 indicated, and injected at the base of one of the last pair of walking legs in amounts 

 varying from 002 ml to 0-05 ml depending on the size of the crab. Crabs were 

 injected in lots of five, and after 5-10 minutes the walking legs were grasped firmly 

 with forceps for one or two seconds while the crab was held in a fixed position. This 

 was usually a sufficient stimulus to produce autotomy in an untreated crab. Legs were 

 grasped in a random order (cf. Welsh and Haskin, 1939) and a record made of the 

 number of autotomies in each crab. For each test the number of legs autotomized 

 appears as the numerator of a fraction with a constant denominator of 40, this being 

 the total number of walking legs possessed by 5 crabs. 



Uninjected U. mordax, stimulated in the manner indicated, autotomized nearly all 

 of their walking legs. Two lots of 5 males each dropped 36 of 40 legs. One lot of 

 females dropped 37 of 40 legs. Two lots of males injected with 0-05 ml of sea water 

 dropped 37 of 40 and 39 of 40 legs. 



Table I shows the effects of extracts of three different species on the tendency to 

 autotomize. It will be seen that the higher concentrations reduced the tendency to 

 autotomize and even prevented any significant number of autotomies at the highest 

 concentration used. The presence of a paralyzing agent in the extracts would account 

 for such results. 



Table 1 

 Effects of several dilutions of tentacle extracts on the autotomy reflex in Uca 



mordax 



Species 



Physalia 

 Aiptasia 

 Condvlactis 



No dilution 1:10 1:100 1:1000 1:10,000 



40 5 40 23/40 40 40 



40 7/40 40/40 



40 9/40 14 40 36 40 



The reason for the great effectiveness of the extract of tentacles of the sea anemone. 

 Condylactis, is not entirely clear. This anemone may actually carry a larger amount 

 of paralyzing substance than Physalia, in a given weight of tentacle, but the 

 ground tentacles used in making this extract stood for a longer period before 

 filtering than in other extractions. This may have released more active material into 



solution. 



Since U. mordax had responded to the extracts by showing clear signs ol paralysis 

 and by a reduced tendency to autotomize their appendages, they were obviously 



* Kindly identified by Dr. Fenner A. Chace of the National Museum. Washington. D.C. 

 L 



