214 PHYSIOLOGICAL CHEMISTRY. 



creatic juice or by soaps formed in other ways can only take place 

 in an alkaline solution. In the contents of the intestine, as long 

 as they are acid, such an emulsion can hardly occur. On the con- 

 trary, it undoubtedly occurs at the point where the fat comes in 

 contact with an alkaline secretion under a mucous membrane, or 

 in general where it meets with sufficient alkali to form an emul- 

 sion. In the acid contents of the intestines of dogs, which had 

 been kept on food rich in fat, LUDWIG and CASH observed no 

 emulsion. After tying the two pancreas excretory ducts they 

 found a remarkably fine emulsion in the chylous vessels, though 

 the fat in the contents of the intestine was not emulsified. In 

 this case it is possible that the free fatty acid which is hardly ever 

 absent in the fat of the food, and which may be produced also by 

 putrefaction in the intestine, forms soaps with the alkali of the 

 mucous coat of the intestine and produces the emulsion in the 

 chylous vessels. 



CLAUDE BERNARD found long ago in his experiments on rab- 

 bits, in which animals the choledochus duct to the small intestine 

 was inosculated above the pancreas passages, that when their food 

 contained a large proportion of fat the chylous vessels of the intes- 

 tine above the pancreas passages were transparent, but below the 

 same they were milky-white, and from this concluded that the bile 

 alone, without the pancreatic juice, does not emulsify fats. DASTRE 

 tried the reverse experiment in dogs, namely, tying the choledo- 

 chus duct and producing a biliary fistula, through which the bile 

 would flow into the intestine below the mouth of the pancreatic 

 passages. When the animals were killed after a meal rich in fat, 

 the chylous vessels were first milky-white below the opening of the 

 biliary fistula. DASTRE draws the following conclusion from this : 

 that combined action of the bile and the pancreatic juice is neces- 

 sary for the absorption of the fats a deduction which coincides 

 with the above-mentioned observations of NENCKI. 



Bile has no solvent action on proteids, but still it may have an 

 influence on their digestion. The acid contents of the stomach, 

 containing an abundance of proteids, give with the bile a precipi- 

 tate of proteids and bile-acids. This precipitate carries a part of 

 the pepsin with it, and for this reason and on account of the partial 

 or complete neutralization of the acid of the gastric juice by the 

 alkali of the bile and the pancreatic juice the pepsin digestion can- 



