ABSORPTION. 517 



of the fatty acids, but as SANDMEYER found in dogs deprived of their 

 pancreas, that the fat absorption was raised by giving chopped pancreas 

 with the fat, this can hardly be a sufficient explanation. The reason 

 for this is perhaps that after the extirpation of the pancreas the splitting 

 of the fat is chiefly brought about by bacteria in those parts of the intestinal 

 canal where the conditions for absorption are not favorable. 



The soluble salts are also absorbed with the water. The proteins, 

 which can dissolve a considerable quantity of salts, such as earthy phos- 

 phates which are otherwise insoluble in alkaline water, are of great 

 importance in the absorption of such salts. 



The enzymes may also be absorbed like other soluble constituents of 

 the digestive secretions, as is demonstrated by the passage of pepsin into 

 urine. The occurrence of urobilin in urine attests the absorption of the 

 bile-constituents under physiological conditions despite the fact that the 

 occurrence of very small traces of bile-acids in the urine is disputed. 

 The absorption of bile-acids by the intestine seems to be positively proven 

 by other observations. TAPPEINER l introduced a solution of bile-salts of a 

 known concentration into an intestinal knot and after a time investigated 

 .the contents. He found that in the jejunum and the ileum, but not in the 

 duodenum, an absorption of bile-acids took place, and further that of the 

 two bile acids only the glycocholic acid was absorbed in the jejunum. 

 Further, SCHIFF long ago expressed the opinion that bile undergoes an 

 intermediate circulation, in such wise that it is absorbed from the intestine, 

 then carried to the liver by the blood, and lastly eliminated from the blood 

 by this organ. Although this view has met with some opposition, still its 

 correctness seems to be established by the researches of various investiga- 

 tors, and more recently by PREVOST and BINET, and specially by STADEL- 

 MANN and his pupils. 2 After the introduction of foreign bile into the 

 intestine of an animal the foreign bile-acids appear again in the secreted bile. 



How does the removal of large portions of the various parts of the 

 intestine affect absorption? HARLEY S has been able to perform a par- 

 tial extirpation of the large intestine and in another instance a com- 

 plete extirpation. This last condition increased the feces considerably, 

 especially because of the large increase in the water (fivefold). Fats 

 and carbohydrates were absorbed just as completely as in the normal. 

 The absorption of the proteins, on the contrary, was reduced to only 

 84 per cent as compared to 93-98 per cent in normal dogs. After extir- 

 pation the feces sometimes did not contain any urobilin, or only traces 

 thereof, while bile-pigments existed in large amounts. 



1 Wien. Sitzungsber., 77. 



2 Schiff, Pfliiger's Arch., 3; Prevost and Binet, Compt. rend., 106; Stadelmann, 

 see footnote 1, p. 394. 



3 Proceed. Roy. Soc., 64. 



