Chap, x.] DIGESTIVE APPARATUS IN THE ANIMAL SERIES. 165 



This first portion or oesophagian portion is only distinguished 

 from the stomachal portion by characteristics drawn from the 

 structure of the mucous membrane. Its function, however, is 

 still imperfectly specialised. In effect, at its origin, in the portion 

 which may be called pharyngian, the cavity is in part circum- 

 scribed by the branchial arcs and has consequently respiratory 

 uses. 



The proteus (amphibian) has a conformation more inferior still ; 

 there is no trace in the animal of stomachal dilatation. 



The first portion of the digestive tube of birds ia characterised 

 by diverse dilatations : the first, annexed to the oesophagus, is 

 the crop. Two other divisions are more specially stomachal. 

 They are the gizzard, very rich in glands, then another very 



¥ia. 11. 

 Stomachs of different jpammifers. A, seal. B, "h^tEna. C, Aamsisr. 

 B, lamentine. B, camel. F, sheep. 1. paunch. 2. bonnet. 3. 

 manyplies. 4. caillette. e, cardia, p, pylonj^. 



muscular dilatation, especially in the granivorous birds, and 

 which is sometimes clothed with a corneous layer. This last 

 pouch fulfils especially a mechanical oflS.ce. 



It is only in the mammifers that the stomach becomes 

 regularly transversal (Fig. 11). At the same time it has 

 enlarged, and its walls have not everywhere the same structure. 

 Therein are distinguished, as in man, a cardiacal portion connected 

 with the oesophagus, and a pyloric portion debouching into the 

 intestine. But in certain families of mammifers the division is 

 not merely, as in man, characterised by a difference of structure. 

 Every one knows the stomach with four compartments of the 



