20 STRTTCTURE AWD OFFICE OF THE STOMACH. 



cxcum and colon ; in this respect it approach<?s the kangaroo^ 



and still more closely, the kanguroo rat; its cardiac portion 



is shorter, and its pyloric longer, than in the stomach of that 



aninial, and there is no valvular structure at the orifice of the 



cardia. 



Omithorin- The only real link between tlie stomachs of quadrupeds 



chus, the only and birds is that of the ornithorinchus, wliicli, however, is 



real link be- , ,.,,.,,., 



tween beasts niore an approach to the gizzard, being lined with a cuticle, 



and birds, containing sand, and having the same relative situation to the 

 oesophagus and duodenum. The food of this animal is not 

 known; it is probably of both kinds; the papillae at the py- 

 lorus, which appear to be the excretory ducts of glands, are 

 peculiar to it. 

 Birds of prey. The stomachs of birds of prey are formed upon the same 

 principle as those of carnivorous quad rupeds, but their cavity 

 is more a continuation of the oesophagus, and tUe solvent 

 glands are more conspicuous and numerous. Both these dif- 

 ferences may be accounted for from their swallowing their 

 prey whole, or nearly so; which requires a more direct pas- 

 sage into the stomach, and a gr-eater quantity of secretion from 

 the solvent glands, than when the food has undergone masti- 

 cation. The cardiac portion of these stomachs is very distinct 

 from the pyloric. 

 Snates tur- ^" snakes, turtles, and fishes, the stomachs have the same 



ties, and fishes, characters as in birds of prey, but the cardiac and pyloric 

 portions are still more distinct from each other, and the sol- 

 vent glands are in general distributed over a larger surface of 

 the cardiac portion. 

 General con- From the series of facts and observations which have been 

 elusions. adduced, the following conclusions may be drawn. 



That the solvent liquor is secreted from glands of a some- 

 what similar structure in all animals, but much larger and 

 more conspicuous in some than others. 



That these glands are always situate near the orifice of the 

 cavity, the contents of which are exposed to their secretion. 



That the viscid substance, found on the internal membrane 

 of all the stomachs that were examined recently after death, 

 IS reduced to this state by a secretion from tiie whole surface 

 of the stomach, which coagulates albumen. This appears to 



be 



