Prof. Wagner on the Stinging Organs of the Meduse. 81 
my investigations enable us to approach more nearly the de- 
cision of this question. 
The origin of the stinging is, at all events, to be sought for 
in the external surface of the skin of the Medusz. I have 
observed in a very beautiful and distinct manner the structure 
in the Pelagia noctiluca.* The outer skin is in that species of 
a beautiful brownish violet and reddish colour on the convex 
discoid surface, on the exterior arched edge of the arms, and 
on the lobes of the rim (Fandlappen). This variegated mem- 
brane is easily separated, especially over the greater part of 
the convex surface of the disc, and then there appears the ho- 
mogeneous jelly-like substance which constitutes the real body 
of the animal. Where the red spots occur, we find, after the 
skin is detached, round elevations or inequalities, like warts. 
By the assistance of a low magnifying power the red spots 
appear like collections of very small red grains of pigment, 
n whose vicinity the whole body is covered by that kind of 
epithelium called a Pflasterepithelium, consisting of larger and 
smaller cells, which contain distinct nuclei. It is an epider- 
mis analogous to that of the frogs and many other animals. 
The accumulations of pigment occur especially on the above- 
mentioned arched inequalities, which rise above the surface, 
and have a substratum of muscular fibres. 
Between the red grains of pigment are to be observed round 
balls or bubbles, out of which frequently, by the aid of a power- 
ful magnifying power (for this whole organization can only 
be recognised through the microscope), fine threads are seen 
to project. The largest of these balls present themselves as 
firm well-filled capsules of 2,th part of a line in size, in which 
lies internally a spirally rolled up thread which often comes 
out of itself, but always does so on the application of a slight 
pressure. This thread then appears as a whip-like appendage 
to the capsule, and has a very elegant outline. It is difficult 
to form an idea of its structure ; sometimes it seems as if it 
had a canal. When the capsule is closed, while the thread is 
still rolled up in it, we perceive an inequality to which the 
* The examination was made at Nice and Villafranca in the autumn of 
1839. 
VOL. XXXII. NO. Lx111.—sanuary 1842. F 
