INTRODUCTION. 
XX XIX 
■with impimity. And I liave elsewhere* recorded an in- 
stance, in which a little fish, swimming about in health and 
vigour, died in a few minutes -with great agony, through 
the momentary contact of its lip with one of the emitted 
acontia of Sagartia parasitica. It is worthy of observation, 
that, in this case, the fish carried away a portion of the 
acontium sticking to its lip ; the force with w'hich it ad- 
hered being so great, that the integrity of the tissues yielded 
first. The Acontium severed, rather than let go its hold.'\ 
Now, in the experiments which I have detailed above, 
we have seen that this adhesion is effected by the actual 
impenetration of the foreign body, by a multitude of the 
ecthoreea, whose barbs resist wdthdrawal. So that we can 
with certainty associate the sudden and violent death of 
the little fish with the intromission of barbed ecthorcea. 
I have instituted some experiments with a view to try 
whether acid or alkaline properties could be detected in the 
(presumed) fluid which is discharged. First with a solu- 
tion of indigo, and afterwards with the expressed juice of 
violets, I occupied the plate of the compressorium ; and in 
the flattened drop made the cnidcB in the acontium of S. 
parasitica to emit. In the case of the indigo, the colouring 
matter remained in the form of masses, but the juice of 
violets affords an apparently homogeneous fluid, even "when 
reduced by pressure to an excessively thin film. I could 
not detect, even with the most careful scrutiny, the slightest 
tinge of discoloration of the blue fluid, — not the most 
delicate shade of red or green — along the side of the 
emitted ecthoraa, nor in the vicinity of the cnida. And 
* “ The Aquarium,” ed. 1. p. 115. 
t Dr. Waller has recently recorded an interesting experiment which he 
made with Act. mesembryanthemum. He allowed its tentacles to touch 
the tip of his tongue. “ The result was such as to satisfy the most scep- 
tical 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 bo 
detected. These symptoms continued unabated for about an hour, and a 
slight temporary 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.”— (Proc. Roy. Soc. 
April 14, 1859.) 
