280 Dr. H. Lacaze-Duthiers on the Float of the lanthine. 
or residue of this part in the individuals im his possession which 
wanted it.” 
Dr. Coates confirmed Cuvier’s opinions, and showed that there 
was no anatomical relation between the body and the float*. 
He also found that the latter was entirely secreted by the foot, 
and that when a portion is removed the damage is quickly 
repaired. 
The last author who has paid attention to the float of Janthina 
is Mr. Adamst; his work is recent, dating only three years ago. 
It contains numerous facts which are perfectly correct and prove 
that the author observed the living animal. He says, “ The 
float is attached to the under surface of the caudal end of the 
foot, where what appear to be the muciparous follicles give it a 
striated appearance. . . When the animal is weakly or dead, the 
the float readily becomes detached, for there is no organic con- 
nexion between it and the foot.” This perfectly correct notion 
always recurs, and all the observers who have closely examined 
the matter come to the same conclusion as Cuvier. 
As to the origin of the float, Mr. Adams is less positive. He 
says, “The vesicles are probably formed in the same manner as 
the frothy spume of the little green Homopterous larva which is 
seen on bushes in the spring, and which, in Hampshire, usually 
goes by the name of ‘Cuckoo-spit.”. When a portion is cut off, 
the float is enlarged at the end next the foot of the animal, and 
is not regenerated at the excised part.” We shall see, however, 
that it may be repaired at the point which has been destroyed, 
but that this depends entirely on the position occupied by this 
point. Mr. Adams adds, “ With a pair of sharp-pointed scissors 
I made incisions into the floats, and allowed the air to escape, 
when the animals gradually descended and remained helpless at 
the bottom of the vessel; the floats were not regenerated or 
renewed during the period the animals remained alive.” I call 
particular attention to this passage, which very correctly indi- 
cates a fact, and which I shall cite in favour of the opinion that 
I shall maintain. Lastly, Mr. Adams remarks that crepitating 
portions continue floating until the air which they contain 
gradually escapes and they collapse, and, finally, that the floats, 
when pounded in a mortar, are readily reduced to a mucus. 
Such are the observations that have been made upon the float 
of Fanthina. 
The following are the facts that I have ascertained, and from 
which I deduce the consequences that will be found in this 
article. In the first place, I was struck with the fact that all 
the Janthine absolutely destitute of aériferous vesicles remained 
* Journ. Acad. Nat. Sci. Philad. vol. iv. 
t+ Annals & Mag. Nat. Hist. ser, 3, vol. x. p. 417 (1862). 
