ABSORPTION OF FOOD BY VEINS. 623 



By far the larger quantity of the water of the food and drink, and 

 of the saliva and gastric juice, is taken up by the veins. This process 

 begins immediately, and goes on rapidly, in the stomach; it regulates 

 the consistence of the gastric contents, and the strength and acidity 

 of the gastric juice ; more water, including some of that belonging to 

 the biliary, pancreatic, and intestinal secretions, is taken up by the 

 veins of the intestines ; but much is here absorbed by the lacteals, to 

 form the fluid part of the chyle. The saline constituents of the food 

 are absorbed directly, in chief part, by the veins, these substances, 

 such as chloride of sodium and phosphate of soda, requiring, like 

 water, no digestion ; minute traces of them, however, also enter the 

 lacteals. Sugar and extractive matters likewise enter chiefly by the 

 veins, and but slightly through the lacteals. The organic acids, and 

 their salts, are converted into carbonates, and undergo venous absorp- 

 tion. Alcohol also passes in chiefly, if not entirely, by the veins, and 

 so likewise do the ethereal, odorous, sapid, and coloring matters of 

 the food, and probably also most medicinal and poisonous substances. 

 Venous absorption even begins in the mouth, as may be inferred from 

 the occurrence of taste ; but it is much more active in the stomach 

 and intestines. Soluble albuminoid substances, if not converted into 

 albuminose, may be absorbed directly by the veins of the stomach and 

 small intestine, and certainly by those of the large intestine, as is ex- 

 emplified in the restorative effects of nutrient enemas. The soluble 

 albuminose, the product of digested albuminoid bodies, must also be 

 in part absorbed by the veins ; for the quantity of albumen taken up 

 into the chyle is scarcely equal to that contained in the food. The 

 gelatin-peptone probably enters the veins. Lastly, fatty matters 

 have not been directly proved to be taken up by the veins, though, if 

 in a saponified condition, they may be so, and the capillary network 

 has been seen to assume a turbid appearance, as if containing fat. 

 (Brticke.) Besides this, in cases of disease, not only the coloring 

 substances, but the fatty matters of the bile, enter the circulation 

 through the venous system. The chief channels of entrance of the 

 fatty matters emulsified during the process of digestion, are, however, 

 the lacteal vessels, as is proved by the large proportion of fat in the 

 chyle. 



The veins thus absorb most of the water, and of the saline, saccha- 

 rine, extractive, acid, alcoholic, odorous, sapid, and coloring substances, 

 together with some albumen or albuminose, probably the gelatin pep- 

 tone, and possibly saponified fatty matters. On the other hand, the 

 lacteals absorb the rest of the water, small quantities of the saline, 

 saccharine, and extractive substances, a considerable proportion of the 

 albuminose bodies, and nearly all the fat. In the intervals between 

 the absorption of food, the lacteals of the small intestine, like the 

 lymphatics of other parts of the body, contain only a transparent 

 lymph, and then perform, for the tissues of the intestine, the office of 

 lymphatics generally. The same is true, at all times, of the lymphatics 

 of the stomach and of the large intestine, which never contain chyle, 

 but always lymph. 



It may be presumed that the absorption which takes place from the 



