OF THE STURGEON. 
359 
at P, and descends to form at P the pylorus. These va- 
rieties, in the figure and direction of the stomach, are to be 
ascribed, I conceive, to the opposite states of plenitude and 
emptiness. When the organ is empty, as in my last spe- 
cimen, the curvatures are distinctly exhibited, in conse- 
quence of the strong contraction of the muscular fibres of 
the space between the cardiac and pyloric extremities. 
When it is recently and completely filled, on the contrary, 
the mechanical distension overcoming for the time the mus- 
cular force, not only distends the organ, so as to bring the 
lower and upper curvatures in close approximation, but 
causes the cardiac portion to revolve backwards on the 
pyloric, and thereby render indistinct, if not obliterate, the 
first curvature. But whatever opinion may be entertained 
as to the cause, no doubt can exist as to the fact that the 
stomach, when empty, is a long cylindrical tube, incurvated 
twice on itself in the transverse direction, and enclosing by 
its incurvations an elliptical space ; and that, when filled, it 
assumes the appearance of a musculo-membraoous sac, 
with an antero-posterior incurvation below, and a trans- 
verse one above, and inclosing, instead of an elliptical, an 
oblong triangular space. 
The pancreatoid organ has been sufficiently described 
in the foregoing sketch. I have only to add, that the inner 
surface of this organ appears to secrete a thin fluid, which, 
instead of being conveyed, as in the mammalia.^ to the food, 
is insensibly distilled on the food introduced into its cellu- 
lar compartments, and the chief use of which appears to be 
to render the alimentary mass more fit for the formation and 
separation of chyle. The fleshy substance of which it con- 
sists is liberally supplied with bloodvessels, the chief use of 
which is to secrete this fluid by vascular not follicular ac- 
tion. After the food has undergone this process, the mus- 
cular fibres contract, and propel the food from the cavities 
