DIGESTION. 229 



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 circula- 

 tion, 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 oppo- 

 sition, still its correctness seems to be established by the researches 

 of various investigators, and more recently by PREVOST and BINET, 

 at least to the extent that after the introduction of foreign bile 

 into the intestine of an animal the foreign bile-acids appear again 

 in the secreted bile. 



There are two possible ways in which the absorbed bodies may 

 enter the blood-stream. They may pass into the blood through 

 the chylous vessels and the thoracic duct indirectly, or they may, 

 after they have passed the intestinal epithelium, pass into the 

 blood-capillaries of the villous membranes and so directly into the 

 blood. By the investigations of LUDWIG and his pupils, ROHRIG, 

 ZAWILSKY, v. MERING and SCHMIDT-MULHEIM, as well as by those 

 of HEIDENHAIN and* his pupils, it has now been proved that the 

 fat is driven through the chylous vessels and the thoracic duct to 

 the blood, while on the contrary the bodies soluble in water, such as 

 sugar and salts, are taken up by the blood of the capillaries of the 

 villous membrane and in this way pass into the blood. The reason 

 why the dissolved bodies do not pass into the chylous vessels in 

 larger quantities is explained by HEIDENHAIN to lie in the anatomi- 

 cal situation, the arrangement of the capillaries close under the 

 layer of epithelium. Ordinarily these capillaries find the necessary 

 time for the taking up of the water and the solids dissolved in it. 

 But when a large quantity of liquid, such as a stagar solution, is 

 introduced into the intestine at once, this is not possible, and in 

 these cases a part of the dissolved bodies pass into the chylous 

 vessels and the thoracic duct (GINSBERG and ROHMANN). 



The question of the absorption of the peptones, albeit in most 

 cases these have not been differentiated from albumoses, has been 

 the subject of numerous investigations. LUDWIG and SCHMIDT- 

 MULHEIM tied the jugular and humeral arteries and lymphatic 

 vessels of both sides of a dog so that the section showed later a 

 complete cutting off of the chyle from the blood-circulation. They 



