ZOOLOGICAL AND BOTANICAL ASSOCIATION. 163 



FRIDAY EVENING, NOVEMBER 19, 1858. 



Rev. Professor Haughton, A. M., F. T. C. D., F. R. 8., Vice-President, 



in the Chair. 



The Minutes of last Meeting having been read, were approved of, and 

 signed by the Chairman. 



Dr. M'Donnell read the following remarks : — 



ON THE URTICATING ORGANS OP ACTINIA. 



In the course of last winter I had the honour of making a communica- 

 tion to the Association on the power exercised by the Actiniae of our 

 shores in killing their prey (see ante, page 55). I wish now, through the 

 same medium, to correct the view which I was at that time led to adopt, 

 this power is due to electrical influence. 



In the communication alluded to, the idea of these creatures being 

 electrical was based on the fact that when the nerve of a frog's limb, 

 prepared after the manner of Matteucci's galvanoscopic frog, is seized by 

 the tentacles of an Actinia, contractions of the muscles promptly ensue. 

 It was admitted, however, that all attempts to produce deflection of the 

 galvanometer needle had failed, and this being the very doubtful state 

 of the question, I ventured to look forward to the pleasure of making 

 another communication on the subject when I had further opportunities 

 of examining the Actiniae in health and vigour. I have now had these 

 opportunities, and have found that the most delicate electrometers are 

 unaffected by them. But I conceive that by the following simple, and 

 indeed obvious experiments, all idea of the Anemones of our coasts 

 being electrical may be set aside. 



Having prepared a galvanoscopic frog's limb, with the nerve as long 

 as possible, it is laid on a piece of perfectly clean glass, so that the nerve 

 hangs over the edge. The pendent nerve is lowered into the water, 

 containing an Anthea, and the nerve is brought in contact with a single 

 one of the long tentacles of this creature. Immediately vigorous con- 

 tractions follow in the muscles of the limb, and if everything be left 

 undisturbed, these twitchings will continue for some minutes after the 

 nerve is withdrawn. If, however, a thread be tied round the nerve 

 below the point where the tentacle of the Anthea touched it, all twitch- 



