Defence among certain Meduse. 343 
other genera of the groups in which they exist. The new 
method of defence is found, as far as known, only among 
the Siphonophores, and is limited to one or two genera. 
Let us, on the threshold of our study, consider the history 
of the discovery of the structures in which this peculiar power 
is thought to be lodged. 
In the year 1880, while engaged in the study of an 
Agalma, found at Villa Franca, South France, I noticed on 
the covering-scales certain coloured bodies which resembled 
in distribution in longitudinal rows the nematocysts which 
are ordinarily found on these structures. In the same year 
(1880) I described and figured these bodies, and called 
attention to the fact that when the covering-scale is broken 
from its connexion with the axis a coloured fluid is emitted 
from these organs. A covering-scale, ruptured from its con- 
nexion, was seen to pour out a considerable quantity of yellow 
fluid and to discolour the water in the immediate vicinity. 
When irritated, even while the bract is attached, the animal 
was supposed to discharge the colouring-matter in the same 
way although not in the same quantity. A similar pheno- 
nenon, connected with other organs, had already been 
described, for a discharge of colouring-matter from the tasters 
of Forskalia had been observed and mentioned by Kolliker ; 
but, as far as known, no one had spoken of a like power of 
the chromatic “ cells” or glands of the covering-scales of any 
Siphonophore. 
My observations were not verified, or, at least, were not 
mentioned, by those who studied the Mediterranean Physo- 
phores up to the close of last year, when Dr. M. Bedot* again 
took up the subject, and from a study of what he regards a 
new species of Agalma (A. Clausi), possibly the same as 
mine, or, at least, found in the same locality, described and 
figured these glands again, generously quoting my description 
of eight years ago. His additions to our knowledge of the 
subject are so important that I have taken the liberty of 
quoting from his account somewhat at length. 
Bedot says (p. 79) :—‘‘ Ce qui donne un aspect particulier 
au bouclier, c’est la présence, 4 sa surface, d’un grand nombre 
de petites taches d’un rouge-carmin foncé (fig. 13, g/l). 
Lorsqu’une de ces Agalmes est capturée, elle rejette une 
quantité trés considérable de matiére colorante d’un rouge 
jaune trés intense. Pour Vobserver facilement, on est obligé 
de changer plusieurs fois l’eau du bocal ot elle se trouve. Au 
premier abord, j’ai cru que cette matiére colorante provenait 
* ¢Tirage a part du Recueil Zoologique,’ t. vy. fase. 1. “ Sur Y Agalma 
Clauss” © ip S14 wi 
lausi. 
