264 M. G. Lunel on Commensalism of a 
If we now consider the urticating cells we shall find that 
they may be compared both with the epithelial muscular cells 
and with the dermal gland-cells. Certainly in all cases, with 
the exception of Physalia, their glandular nature comes most 
prominently forward, for we have a plasma-derivative which 
is thrown off outwards, and consequently may be regarded as 
a secretion, while usually there is no contractile plasma- 
derivative ; and we are not justified in speaking of muscles 
when we describe a structure which certainly contracts on 
irritation, but in which two kinds of substance are not recog- 
nizable, and in which therefore no profound division of labour 
has taken place in a contractile and a plasmatic part. 
Independently of this, however, the double irritability of 
the cnidoblasts is in favour of the view that there may be 
“neuromuscular cells”? which occur together with sense- 
organs and ganglion-cells, a view which has been opposed by 
Claus, the brothers Hertwig, and myself. But the cnidoblasts 
are such peculiar structures that we can scarcely draw any 
conclusion from them as to epithelial muscular cells, so that 
the neuromuscular theory can hardly be supported by them. 
The glandular nature of the cnidoblasts becomes particularly 
probable if we accept the homology between adhesive granules 
and urticating capsules; and I would therefore regard the 
cnidoblasts as unicellular dermal glands. 
XXXIJI.—On a Case of Commensalism of a Caranx and a 
Crambessa. By M. Goprerroy Lunet *. 
THE case which has furnished me with the subject of the 
present memoir relates to animals belonging to very different 
classes, namely Fishes and Meduse. Numerous memoirs, 
the enumeration of which would be out of place here, have 
been published by the older and more recent naturalists upon 
the organization and anatomy, or upon the development or the 
zoclogical characters of the animals of the latter class. I shall 
therefore confine myself to referring, at least in part, to what 
has been said upon their mode of alimentation. 
The Meduse feed upon small naked pelagic animals, and 
even, according to some authors, upon small fishes, which ‘they 
* Translated by W. 8. Dallas, F.L.S., from the ‘ Bibliothéque Univer- 
selle,’ période 3, tome x., Archives des Sciences, p. 271, September 15, 
1885. 
