84 



THE HOESE IN HEALTH AND DISEASE 



of 12 pounds of hay, 6 pounds of oats, and 3 pounds of bran passed 

 29 pounds 13 ounces of feces in twenty-four hours. It takes about 

 four days for food to pass through the aUmentary tract of the horse, 

 but solid bodies have been found in the feces after twenty-four 

 hours. 



Meconium is the fecal material found in the intestines of the 

 fetus. It consists largely of waste products from the liver. The 

 first milk (colostrum) contains substances which hasten bowel 

 action and cause the meconium to be expelled soon after birth. 



Fig. 24. — Diagrammatic representation of the two paths of absorption; 

 V, Veins of the mesentery which unite to form the portal vein, P.V. ; H.V., 

 hepatic vein; P.V.C., posterior vena cava; L, lacteals which convey through 

 mesenteric lymph-glands, M, to the reoeptaculum chyli, R.C.; L.J.V., left 

 jugular vein; R.J.V., right jugular vein; B.V., brachial vein; A.V.C., anterior 

 vena cava. 



The essential points mentioned in connection with digestion 

 may be summarized as follows: Digestion involves a reduction of 

 foods to their simplest forms, and in most cases they are probably 

 made water-soluble. The carbohydrates are changed to sugars, the 

 fats to fatty acids and glycerin, the proteins to amino-acids, and 

 the cellulose to decomposition products. With the possible excep- 

 tion of the latter, all afford available heat for the body when under- 

 going their respective modifications. 



(E) Absorption from the Digestive Canal. — The process of 

 absorption is complicated from the fact that there are two paths 

 by which the products of digestion may enter the general circula- 



