56 THE AMINO ACIDS 



realizes the great number of compounds that may find 

 their way into the blood stream. Leaving out of con- 

 sideration any residue of undigested protein we may 

 confine our attention to the possibilities of proteose and 

 peptones, the amino acids and the derivatives of the 

 latter. The evidence of the absorption of proteose and 

 peptone derivatives is decisive since Folin and Denis 

 have demonstrated an increase in the non-protein 

 nitrogen of the blood after placing Witte peptone in a 

 ligatured loop of the large intestine. The absorption 

 from the large intestine, however, is much slower than 

 obtains in the small intestine. In a similar manner 

 Folin and Denis have observed the absorption of dif- 

 ferent amino acids and urea. Throughout the entire 

 intestinal canal, therefore, the absorption of amino 

 acids may be regarded as a normal process. 



The absorption of the well-known typical products 

 of putrefaction needs only brief description since their 

 fate has long been recognized. Absorption of indole, 

 skatole, phenol, cresol, etc., is certain since their 

 addition products are found in the urine. Thus indole 

 is absorbed, carried to the liver through the portal 

 vein, oxidized to hydroxy indole (indoxyl), combined 

 with sulphuric acid and eventually is eliminated as the 

 potassium salt, indican its amount being indicative 

 of the extent of intestinal putrefaction. Or indole may 

 be combined in part after oxidation with glycuronic 

 acid and be excreted as a glycuronate. Phenol and 

 cresol may likewise be eliminated in the urine as 

 ethereal sulphates. 



