398 THE DIGESTIVE APPARATUS IN MAMMALIA 



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



^"'^Sctuation—Form—Eelaiions.—SU-aated 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 slightlv 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 poderiorface lying 

 to\™rds°the paunoii : a great curvature, turned upwards, and fixed in the posterior fissnre 

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

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

 the reticulum ; a left extremity, exhibiting the nech, which corresponds to the orifice oi 

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

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

 that of the anterior extremity, Wt much less marljcd. 



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 



Fi?. 193 



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

 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 borcTer attached either 

 to the great curvature or to the faces of the organ, and a free concave border tm-ned 

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

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

 base of the leaves to the entrance of the abomasnm. At the latter aperture iHej 

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

 multitude of very hard mamillary papillse, resembling grains of millet, which are more 

 developed and conical on some of the leaves than others. " All these lamellar prolongations 

 are far from btinu' of the same extent : twelve to fifteen are so wide that thti)' 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 seamdary 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 laminse more or less salient. In a general way, the laminte 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 diy, and sometimes even hardened into compact flakes. 



