118 



DIGESTION". 



Fig. 17. 



COMPOTND STOMACH OF Ox. 

 gus 6. Rumen, or first stomach, c. Reticulum, or 

 second, d. Omasus, or third, e Abomasus, or 

 fourth. /. Duodenum. (From Rymer Jones.) 



a lioney-combed or reticulated appearance. Here the food, already 



triturated in the mouth, and 

 mixed with the saliva, is further 

 macerated in the fluids swal- 

 lowed by the animal, which al- 

 ways accumulate in considerable 

 quantity in the reticulum. The 

 next cavity is the omasus, or 

 " psalterium" (d\ in which the 

 mucous membrane is arranged 

 in longitudinal folds, alternately 

 broad and narrow, lying parallel 

 with each other like the leaves 

 of a book, so that the extent of 

 mucous surface, brought in con- 

 tact with the food, is very much 



(Esopha- t 



increased. The exit from this 

 cavity leads directly into the 

 abomasus, or " rennet" (e), which 

 is the true digestive stomach, in which the mucous membrane is 

 softer, thicker, and more glandular than elsewhere, and in which 

 an acid and highly solvent fluid is secreted. Then follows the in- 

 testinal canal with its various divisions and variations. 



In the carnivora, on the other hand, the alimentary canal is 

 shorter and narrower than in the preceding, and presents fewer 

 complexities. The food, upon which these animals subsist, is softer 

 than that of the herbivora, and less encumbered with indigestible 

 matter ; so that the process of its solution requires a less extensive 

 apparatus. 



In the human species, the food is naturally of a mixed cha- 

 racter, containing both animal and vegetable substances. But the 

 digestive apparatus in man resembles almost exactly that of the 

 carnivora. For the vegetable matters which we take as food are, 

 in the first place, artificially separated, to a great extent, from indi- 

 gestible impurities; and secondly, they are so softened by the 

 process of cooking as to become nearly or quite as easily digestible 

 as animal substances. 



In the human species, however, the process of digestion, though 

 simpler than in the herbivora, is still complicated. The alimentary 

 canal is here, also, divided into different compartments or cavities, 

 which communicate with each other by narrow orifices. At its 



