360 ON THE ANATOMICAL PECULIARITIES 
into the duodenum, in which the absorption of chyle appears 
chiefly to proceed. 
With the view of ascertaining the structure of the axis 
or central pillar of the spiral valve, I injected, in the small 
specimen, a large vein ; and, in the larger one, the arteries 
of the intestinal canal, at the mesenteric side of the intestine. 
The injection, which filled the small vessels of the bowel 
very well, shewed that the axis consists, not of mesenteric 
trunks, as might be inferred from the statement of Dr 
Monro secwidus, but of minute capillaries distributed 
through cellular tissue. No large vessels can be recognised, 
although the mucous surface is reddened by the injection, 
and the axis appears to be simply very well supplied with 
minute vascular ramifications. It is further remarkable, 
that the membrane on the right side of the axis and the 
valvular slips are in general much better supplied with 
bloodvessels than the membrane on the left side of the axis. 
The result of this injection, I conceive, decides the ques- 
tion of the structure of the axis. 
In the account of the large sturgeon above given, I 
have described minutely the reticular structure of the in- 
ner membrane, and have directed attention particularly to 
the fact of the alternation of this structure with smooth 
membrane on the right and left side of the axis. In the 
small specimen before me at this moment (August 7.), the 
reticular structure is not yet distinctly formed ; and its com- 
mencement only can be recognised in the shape of minute 
specks, which are red-coloured from the injection, dissemi- 
nated over the mucous membrane. 
In the present specimens also, I had an opportunity of 
observing distinctly the different orifices at the anal fin, 
which in the sturgeon are peculiar, and of which, therefore, 
I have given a representation in the engraving. 
The space which may be named the outlet, or common 
