228 Royal Society :— 



without injury ; the strongest action of an electro-magnetic machine 

 on Du Bois Reymond's principle, which affected myself violently up 

 to the elbows, appeared to be easily endured by them. 



The above experiment is quite sufficient to show how impossible it 

 is to attribute the fatal influence of the Actiniae to simple electrical 

 action. 



In order to elucidate the real power of the Actiniae — after having 

 in vain exposed the finger on which the cuticle had been softened by 

 soaking in water — considering that the tongue was better adapted 

 for the purpose in view, by reason of the thinness of its cuticle, I 

 presented its apex to the tentacles of an Actinia mesembryanthemum, 

 of about the size of a half-crown piece. The result was such as to 

 satisfy the most sceptical respecting the offensive weapons with 

 which it is furnished. The animal seized the organ most vigorously, 

 and was detached from it with some difficulty after the lapse of about 

 a minute. Immediately a pungent acrid pain commenced, which 

 continued to increase for some minutes until it became extremely 

 distressing. The point attacked felt inflamed and much swollen, 

 although to the eye no change in the part could be detected. These 

 symptoms continued unabated for about an hour, and a slight tem- 

 porary relief was only obtained by immersing the tongue in cold or 

 warm water. After this period the symptoms gradually abated, and 

 about four hours later they had entirely disappeared. A day or two 

 after, a very minute ulceration was perceived over the apex of the 

 tongue, which disappeared after being touched with nitrate of silver. 



I have subsequently frequently repeated this experiment on myself 

 and others, using greater precaution, and have invariably obtained 

 similar symptoms of urtication. In only one instance has a minute 

 ulceration been the consequence. 



It is very evident therefore that the Actiniae act by means of an 

 acrid irritant poison, similar in some respects to that of the wasp, or 

 of snakes, which quickly spreads through the system of the Annelida, 

 producing the above-mentioned results. 



It remained to determine whether the poisoned weapons existing 

 in such numbers over the surface of the Actiniae were left in the part 

 attacked. For this purpose I stretched a thin India-rubber mem- 

 brane over a glass tube. After its seizure by the Actinia, I found 

 that under the microscope it was studded in many points with the 

 poison darts inserted slightly in the membrane, witiiout their having 

 penetrated through. In this respect my observations difi'er from 

 those of Mr. Gosse, who considers that a fragment of cuticle from 

 the hand was perforated by these darts. 



May 19, 1859.— Major-General Sabine, R.A., Treas. and V.P., 

 in the Chair. 

 " On the Anatomy of Victoria Regia'' Part II. By Arthur 

 Henfrey, Esq., F.R.S., F.L.S. &c.. Professor of Botany in King's 

 College, London. 



This paper is a continuation of one published in the Philosophical 

 Transactions for 1852 (p. 289), and discusses the general question 



