TEE STOMACH. 397 



exfoliated patches on the surface of this layer. This is a sufficient indication of the 

 activity of the secretion of the epithelium, and the rapidity of its renovation. 



RETICTJLUM (HONEYCOMB) (Figs. 192, 193). Situation Form Relations. This, the 

 smallest compartment, is elongated from one side to the other, slightly curved on itself, 

 and placed transversely between the posterior face of the diaphragm, in one direction, 

 and the anterior extremity of the left sac of the rumen in the other ; the latter only 

 appearing, externally, to be a prolongation, or a diverticulum of the rumen. 



It has two faces, two curvatures, and two extremities. The anterior face adheres to 

 the phrenic centre of the diaphragm by cellular tissue. The posterior face lies against 

 the anterior extremity of the rumen. The great inferior or convex curvature occupies 

 the suprasternal region. The lesser, superior, or concave curvature partly responds to 

 the lesser curvature of the omasum. The left extremity is only separated from the rumen 

 by a fissure, which lodges the inferior artery of the reticulum. The right extremity forms 

 a globular cul-de-sac, in relation with the base of the abomasum. 



Interior (Fig. 193). The internal surface of the reticulum is divided by ridges of 

 the mucous membrane into polyhedral cells, which, in their regular arrangement, look 

 like a honeycomb; they are widest and deepest in the cul-de-sac, and become gradually 

 smaller in approaching the superior curvature. The interior of these cells is divided 

 into smaller spaces, included one within the other, by secondary and successively-decreas- 

 ing septa. The principal septa oifer on their free border a series of conical prolonga- 

 tions, with a rough hard summit; while their faces are studded with minute, blunt, or 

 pointed papillae. The secondary septa also show similar prolongations ; and those on 

 their free margin are even more developed than on the chief septa. Lastly, from the 

 bottom of the cells spring up a crowd of long, conical, and very pointed papillae, resem- 

 bling stalagmites in their arrangement. 



It may be noted that the foreign bodies so frequently swallowed by Ruminants, are 

 usually lodged in the reticulum ; therefore it is that at the bottom of the cells are found 

 either small stones, and needles or pins, often fixed in the intermediate septa, or nails, 

 scraps of iron, etc. The interior of the reticulum communicates with the left sac of the 

 rumen by the orifice already described, and with the omasum by a particular open- 

 ing, placed near the middle of the small curvature, though a little more to the right 

 than the left. This opening, eight or ten times smaller than the preceding, is 

 connected with the infundibulum of the cardia by a remarkable groove (or channel), 

 the cesophageal, which will be described separately, as it does not properly belong to the 

 reticulum. 



Structure. The serous membrane does not cover all the anterior surface of the organ, 

 as the latter adheres to the posterior face of the diaphragm. The muscular tunic is much 

 thinner than that of the paunch, and more fasciculated. The fibres pass in the same 

 direction. The corium of the mucous membrane sends a prolongation into each of the 

 septa of the alveoli, and into each of the conical papillae on these septa, or to the bottom 

 of these alveoli. The stratified pavement epithelium is very thick, and its horny layer 

 is very developed at the summit of the papillae. 



CESOPHAGEAL GROOVE (Fig. 193). This gutter is so named because it appears to 

 continue the oesophagus to the interior of the stomach. It extends on the lesser 

 curvature of the reticulum from the cardia to the entrance of the omasum ; commencing 

 in the rumen, it belongs to the reticulum for the remainder of its extent. Measuring 

 from six to eight inches in length, this demi-canal is directed from above downwards, 

 and from left to right, between two movable lips, which are fixed by their adherent 

 border to the superior wall of the reticulum. These two lips are thickened at their free 

 margins, which look downwards and to the left. At their origin at the cesophageal 

 infundibulum, they are thin and but slightly elevated ; but they become thick and 

 salient on arriving near the orifice of the omasum, which orifice they surround, though 

 they neither meet nor become confounded with each other. 



The mucous membrane covering these two lips is much corrugated outwardly and 

 on the free border ; but in the interior of the groove it possesses all the characters of the 

 cesophageal mucous membrane in being smooth, white, and ridged longitudinally ; near 

 the orifice of the omasum it has some large conical papillae 



If this membrane be removed to study the subjacent tissue, the following arrangement 

 is observed : At the bottom of the channel, and in the space comprised between its two 

 lips, are transverse muscular fibres, which belong to the rumen or reticulum. The lips 

 themselves are entirely composed of longitudinal muscular fasciculi, particularly abun- 

 dant towards the free border ; these fasciculi are confounded with the proper fibres of the 

 stomach towards the extremities of the canal, and are carried from one lip to the other 

 in forming loops around the orifices which communicate by this canal. 



OMASUM (Psalterium, MANY-PLIES, MANY-LEAVES, or MANYPLUS. Fig. 192). In the 



