ABSORPTION. 425 



as soon as it is swallowed, arid that very little of it is absorbed from 

 the stomach. Of 500 cc. given by mouth to a large dog, only 5 cc. 

 were absorbed in 25 minutes, the rest having passed into the intestine. 

 Peptones and sugars are absorbed in the stomach, but only to a limited 

 extent, and the same is true of salts. Fats are not absorbed at all in the 

 stomach. In all cases absorption from the stomach is much increased 

 by alcohol and condiments, such as pepper and mustard. 



In the Small Intestine. All the products of digestion are absorbed 

 in the small intestine, as is abundantly shown by experiments. The 

 absorption of fats has been already described. Recently absorption 

 from the small intestine has been studied in the human subject in the 

 case of a patient who had a fistulous opening in the lower part of the 

 ileum. Eighty-five per cent of the proteid of a test-meal was absorbed 

 before the food reached the fistula. Though water and salts are freely 

 absorbed, the intestinal contents does not lose much in bulk or fluidity 

 because of the quantity of water added in the alimentary secretions. In 

 absorption, sugar is changed either just before or during its passage 

 through the wall of the intestine from maltose into dextrose. 



In the Large Intestine. A great deal of absorption takes place in 

 the large intestine. This is evident from the fact that the intestinal 

 contents is very fluid when it enters the large intestine, and almost 

 solid when it leaves it. Its contents passes through the large intes- 

 tine very slowly, usually occupying about 12 hours. In addition to 

 water and salts, the sugar, proteid, and fats not absorbed in the small 

 intestine are almost entirely absorbed here. 



The power of absorption in the large intestine sometimes forms an 

 important feature in medical practice. When patients cannot swallow 

 solid or liquid food, or retain what has been swallowed, they may be 

 nourished by rectal feeding. The large intestine shows a remarkable 

 power in its ability to absorb unchanged albumins, such as white of egg, 

 as well as peptones and proteoees. 



In the stomach as well as in both the large and small intestine, the 

 absorption of water, salts, proteids, and sugars takes place chiefly into 

 the blood-vessels. 



Through the Skin. It has been shown that metallic preparations 

 rubbed into the skin have the same action as when given internally, 

 only in a less degree. Mercury applied in this manner exerts its spe- 

 cific influence upon syphilis, and excites salivation; potassio-tartrate of 

 antimony may excite vomiting, or an eruption extending over the whole 

 body; and arsenic may produce poisonous effects. Vegetable matters, 

 also, if soluble, or already in solution, give rise to their peculiar effects, 

 as cathartics, narcotics, and the like, when rubbed into the skin. The 

 effect of rubbing is probably to convey the particles of the matter into 



