398 



THE DIGESTIVE APPARATUS IN MAMMALIA 



Ox, this compartment is larger than the reticulum, but in the Sheep and Goat it is 

 smaller. 



Situation Form Eelations. Situated above the cul-de-sac of the reticulum and the 

 anterior extremity of the right sac of the rumen, this compartment, when distended, has an 

 oval form, is slightly curved in an opposite direction to the honeycomb division, and 

 depressed from before to behind. It has, therefore, an anterior face, applied against the 

 diaphragm, to which it is sometimes attached by connective tissue ; a posterior face lying 

 towards the paunch : a great curvature, turned upwards, and fixed in the posterior fissure 

 of the liver by an omental frsenum which is continued on the lesser curvature of the 

 ubomasum and duodenum ; a lesser curvature, which looks downwards and responds to 

 the reticulum ; a left extremity, exhibiting the neck, which corresponds to the orifice of 

 communication between the reticulum and many-plies ; a right extremity, continuous 

 with the base of the abomasum, from whicli it is separated by a constriction analogous to 

 that of the anterior extremity, but much less marked. 



Interior. This compartment shows in its interior the two apertures placed at its extre- 

 mities. The right orifice, opening into the ubomasum, is much wider than the left, which 



Fig. 193 



2 



SECTION OF THE WALL OF THE OMASUM OF THE SHEEP : FROM THE GREAT CURVATURE, 

 SHOWING THE ORIGIN OF THE LEAVES. 



P, Peritoneum; M, The two muscular layers; E, Epithelium; 1, 1, Principal leaves 

 at their origin; 2, Secondary leaf; 3, 3, Leaves of the third order; 4, Denticu- 

 lated lamina ; 5, 5, Two planes of muscular fibres ascending into the principal 

 leaves, some issuing from the muscular layer of the organ. 



communicates with the reticulum. The cavity which these orifices bring into communica- 

 tion with the adjoining compartments, offers one of the most curious arrangements met with 

 in the viscera ; it being filled by unequally-developed leaves of mucous membrane, whicli 

 follow the length of the cavity. These laminae have an adherent border attached either 

 to the great curvature or to the faces of the organ, and a free concave border turned 

 towards the lesser curvature. They commence at the side of the orifice of the reticulum 

 by denticulated ridges, between which are furrows, and which are prolonged from the 

 base of the leaves to the entrance of the abomasum. At the latter aperture tney 

 disappear altogether, after rapidly diminishing in height. Their faces are studded by a 

 multitude of very hard mainillary papillae, resembling grains of millet, which are more 

 developed and conical on some of the leaves tha n others. All these lamellar prolongatii >ns 

 are far from beiny; of the same extent : twelve to fifteen are so wide that thtir free border 

 nearly reaches the lesser curvature of the viscus, and between these principal leaves are 

 others which, though regularly enough arranged, are more or less narrower. At first 

 there is remarked a secondary leaf, half the width of the chief ones, between which it is 

 placed ; then, on each of its sides, another, one-half narrower ; and, lastly, at the base of 

 these, two denticulated laminae more or less salient. In a general way, the laminae which 

 are inserted into the great curvature are the longest and widest ; and those attached to 

 the faces of the viscus become shorter and narrower as they draw nearer the lesser 

 curvature. The space comprised between these prolongations is always filled by very 

 attenuated alimentary matters, which are usually impregnated by a very small quantity 

 of fluid, but are also often dry, and sometimes even hardened into compact flakes. 



