SIGNIFICANCE OF KUPFFEK’s VESICLE. 
7 
of it which is not represented by the body cavity. In the 
Teleostean it is never open to the exterior, but this need not 
surprise us since the cavity of the otocvst, or of the crystal- 
line lens, or of the neurochord, is never open to the exterior 
in the Teleostean ; it is very doubtful also whether the neuren- 
teric canal ever contains a lumen in Teleosteans. The intestine 
of the herring is, I believe, formed in exactly the same way as 
the intestine of the Elasmobranch or Amphibian from the 
gastrula-cavitv ; fig. 5 shows that the floor of the intestine has 
been formed from the periblast. 
It is of importance as favouring my view that in many 
Teleosteans Kupffer’s vesicle is visible at a much earlier stage 
than the one in which I have seen it in the herring. In 
Ofasterosteus aculeatus as described in Kupffer’s paper 
of 1868, it is present when the blastoderm has got little beyond 
the equator of the yolk. The same is the case, as has been 
seen from the description of Agassiz and Whitman, in Cteno- 
labrus and probably in many other cases. This brings the 
period of the existence of the vesicle very closely into agree- 
ment with that of the existence of the gastrula cavity in 
Elasmobranchs. I am unable to say whether there is a neuren- 
teric canal or anything representing it in the herring, which 
comes into relation with Kupffer’s vesicle. On my view 
one would expect such a relation, but I must test this in the 
future. 
I do not know whether to rejoice or regret that only in 
copying out this paper for the press I have found that a paper 
appeared in 1880, by M. Henneguy, 1 which advocates very 
much the same view as I now put forward. I have not yet 
referred to the paper and therefore do not know if M. Henneguy 
cut any sections. I found a few words which I had missed in 
the paper by Kingsley and Conn, stating that Henneguy 
believed he had found traces in the perch of an opening of 
invagination leading to the vesicle, and homologized the cavity 
with the primitive intestine in Cyclostomi and Batrachia, and 
the opening with the anus of Rusconi. Agassiz and Whitman 
1 ‘ Annals and Mag. Nat. Hist.,’ ser. v, vol. vi. 
