ON THE DIGESTIVE ORGANS, AND THEIR APPENDAGES. 133 



Capybara, the Coipus, the Capromys, the Beaver, &c., present us with 

 this construction of the fauces, which was first pointed out in the 

 Capybara, by Mr. Morgan, in Linn. Trans., from whose illustration, 

 engraved in that work, the annexed figure (132), representing the 



funnel-shaped constriction of the 

 fauces, a, and the minute ceso- 

 phageal opening, with its sphincter 

 muscle, 6, is taken. (See, also, ac- 

 count of dissection of the Capromys, 

 in Proceed. Zool. Soc. L., 1832, p. 

 73 ; and of the Coipus, idem, 1835, 

 p. 175.) 



By the muscular action of the 

 oesophagus, the food is carried 



Fauces of the Capybara. . , , . . . 



through that tube into the stomach, 



the laboratory of digestion. Hitherto the food has only undergone a 

 mechanical operation, the separation of its parts, or their reduction to 

 a soft consistence ; it has now to be converted, by a chemical process, 

 into such a state as to render it fit for being taken up by the lacteals, 

 and for ultimately entering into the composition of the living frame. 

 The principal agent, in effecting this digestive process, is a peculiar 

 fluid, termed the gastric juice, secreted by the coats of the stomach, 

 and which has the singular property of dissolving, or converting, jnto a 

 pulp (termed chyme), all the substances adapted by nature as the food of 

 any given species ; for it would appear, from various experiments, that 

 the especial food of one animal, introduced into the stomach of another, 

 with whose nature it is not consonant, remains almost wholly unaf- 

 fected.* But, besides the gastric juice, which appears to be the secre- 

 tion of minute glands, though it is impossible, in most instances, to de- 

 tect them, a mucous, or mucilaginous fluid is poured out into the sto- 

 mach, the product of various mucous glands, or follicles, and of use in 

 defending the inner coat of the stomach from irritating substances. In 

 the stomach of the Beaver, at its cardiac portion, there is a curious glan- 

 dular apparatus, of a structure resembling that of the tonsils, being com- 

 posed of numerous small glands, or follicles, forming an aggregate of 

 about one inch and a quarter in length, and half an inch in thickness, 

 which, by numerous apertures, pour out a viscid secretion : in the Dor- 

 mouse, a similar structure exists ; and also in the Wombat and the Koala, 

 two marsupial herbivorous animals : this cardiac gland exists, also, in the 

 Duyong. 



* A very remarkable property of the gastric juice is that of correcting putrefaction : it possesses, 

 also, the property of coagulating every animal fluid, as milk, the white of an egg, jelly, &c., a preli- 

 minary to its solution of them into chyme. 



