STOMACH AND INTESTINE. 



303 



eight or nine years ago, the author discovered 

 that all these projections from the surface of 

 the ordinary Ruminant stomach, viz. thevilli, 

 honeycombs, and plies are constructed chiefly 

 of unstriped muscular tissue, lined by scaly 

 epithelium. The uses of such a structure are 

 too obvious to need any comment. The 

 fourth cavity or abomasum, is the true stomach : 

 it secretes* the gastric juice, and possesses 

 the ordinary tubular structure. As regards 

 the uses of these cavities, the bolus is probably- 

 moulded for rumination in the honeycomb, 

 and is thence regurgitated into the gullet ; 

 while a muscular fold forms a direct pathway 

 for the ruminated food to pass at ouce from 

 the oesophagus to the maniplies. 



Pachydennata. The Elephant has a stomach 

 which is elongated, and subdivided by very 

 numerous folds. In other respects it is simple. 

 That of the Rhinoceros is similar ; but the 

 cardiac pouch is devoid of folds. The shorter 

 stomach of the Pig is divided internally by two 

 folds of mucous membrane into three por- 

 tions : a cardiac pouch, a pyloric extremitj-, 

 and an intermediate portion, which receives 

 the cesopliagus. The lesser curvature, and 

 the back of the cardiac pouch, are both occu- 

 pied by a white and dense epithelium, which 

 is similar to that of the oesophagus, and forms 

 a broad quadrilateral band along this aspect 

 of the interior. In the Pecari there are ex- 

 ternal indications of the same subdivisions : 

 but the white epithelium extends over a 

 wider surface; so that it is only the pyloric 

 third, and the lower parts of the middle and 

 cardiac pouches, which exhibit the proper 

 gastric or tubular structure. In the Hippopo- 

 tamus, the stomach is long and tubular, and 

 is complicated by the addition of two pouches, 

 which have a size almost equal to its own, 

 and communicate with its cavity by corre- 

 sponding orifices on the right of the oesophagus 

 and at the back of the cardia. The internal 

 surface of the organ is so folded as to allow 

 the alimentary bolus to enter either of these 

 two cavities.* 



Tne stomach of the Solipeda has a rounded 

 shape, and a cardia and pylorus which are close 

 to each other. The cardiac half of the organ 

 is lined by a white epidermis, which terminates 

 by an abrupt dentated margin. 



" In all these three orders Ruminants, 

 Pachyderms, and Solipeds the intestine is 

 characterized by great length, width, and 

 convolution, and by the possession of a capa- 

 cious caecum. Thus, in the Ruminant sheep, 

 the intestine is thirty times the length of the 

 body. And although in the Soliped horse this 

 proportion sinks to fifteen or twenty, still the 



* The above is a description of the organ in the 

 foetal Hippopotamus, to which alone our present 

 information refers. Cuvier suggests this to have 

 been an incomplete development of a compound 

 organ, akin to that of a ruminant : the stomach 

 being the abomasum, and the diverticula represent- 

 ing the paunch and honeycomb. But the tough 

 and wrinkled character of the mucous membrane 

 which lined the supposed abomasum in the greater 

 part of its extent seerns to negative this view. 



sacculation of the caecum and colon which ob- 

 tains in this and the Pachydermatous order per- 

 haps compensates such a diminution in length. 

 Theilio-caecal valve is represented by a narrow 

 passage, the mucous membrane of which forms 

 six or eight thick longitudinal folds. The 

 caecum, smallest in the Pachyderm, attains its 

 maximum size in the Soliped ; being, in the 

 Horse, two feet long, and thrice as capacious 

 as the stomach. In one Pachyderm the Cape 

 Hyrax two additional c&ecal tubes open into 

 the large intestine by wide apertures. 



In the Rodentia the stomach is separated 

 by an external constriction into two portions: 

 a cardiac, clothed with a thick epidermis, 

 and a pyloric, occupied by a mucous mem- 

 brane which has the ordinary tubular struc- 

 ture. The size of the former pouch varies in 

 different genera ; the latter sometimes pre- 

 sents an imperfect subdivision. The whole 

 organ occasionally approaches a conical or 

 spherical shape. In the Beaver and Muscar- 

 din, the stomach is complicated by the addi- 

 tion of glandular crypts and caeca, the im- 

 port of which is unknown. The intestine of 

 the Rodent is very long and convoluted, and 

 the small and large intestine are of nearly 

 equal diameter ; but the latter is deeply sac- 

 culated. The caecum is usually very large, 

 and is sometimes subdivided by spiral or cir- 

 cular folds. But in the omnivorous Rat it is 

 small ; and in the Dormouse it is altogether 

 absent. 



Marsnpialia. In a large proportion of this 

 order, the stomach has a considerable resem- 

 blance to that of the human subject. Such 

 an organ is found in both carnivorous and 

 herbivorous Marupialia : and indeed, it is 

 difficult to point out any differences in its 

 size or shape which are distinctly referrible to 

 the habits of its possessors. In some, how- 

 ever, a stomach oF very similar outside shape 

 exhibits a lesser curvature, which is oc- 

 cupied by a gastric gland like that of the 

 Beaver, composed of numerous irregular 

 crypts. In the Kangaroo (Mao-opus) both the 

 shape and the structure of the organ differ 

 widely from the preceding. The stomach is 

 of a length which equals that of the whole 

 body ; the cardiac pouch is subdivided into 

 two caeca ; and the middle part of the organ 

 is sacculated by three bands of longitudi- 

 nal muscular fibres, so as closely to resem- 

 ble the ordinary arrangement of the colon, 

 except that the interspace between the upper 

 two, or that third of the surface which occu- 

 pies the lesser curvature, is not sacculated. 

 The gastric gland is broken up into numerous 

 follicles, which are placed in three rows 

 parallel to the longitudinal muscular bands. 

 The mucous membrane of the oesophagus 

 is continued right and left of the cardiac 

 orifice for a considerable distance; some- 

 what as in the stomach of the Pig. The re- 

 mainder of the mucous membrane is of the 

 ordinary soft character. 



The "intestine of the Marsupial is also sub- 

 ject to great differences. The carnivorous 

 members of the class are devoid of a caecum. 



