492 DIGESTION. 



it seems, according to ABDERHALDEN, LONDON, OPPLER and REEMLiN, 1 

 is similar to the artificial digestion with trypsin, namely, that the destruc- 

 tion takes place step-wise, that certain ammo-acids, such as tyrosine, 

 are split off earlier than others. 



The decomposition products of the proteins formed by the action of 

 gastric juice can, according to LONDON, 2 be absorbed without further 

 cleavage by the pancreatic juice, and a further cleavage in the intestine 

 seems to be more necessary for assimilation than for absorption. 



The carbohydrates and the fats (LEViTES 3 ) may be so completely 

 split in the stomach and small .intestine that their absorption is com- 

 plete before the contents pass into the caecum. According to LONDON 

 and POLOWZOWA 4 a strong cleavage of starch, dextrins and disaccharides 

 takes place, especially in the duodenum, while the absorption is less 

 strong here. The carbohydrates are here prepared for the absorption 

 taking place in the .lower parts of Jie intestine, though the cleavage also 

 goes on in the other parts, .namely in the jejunum and the upper part 

 3f the ileum. 



As above remarked, ordinarily no putrefaction takes place in the 

 small intestine, but occurs generally only in the large intestine. This 

 putrefaction of the proteins is not the same as the pancreatic digestion. 

 In putrefaction the decomposition goes much further and a mixture of 

 products is obtained which have become known through the labors of 

 numerous investigators, especially NENCKI, BAUMANN, BRIEGER, H. and 

 E. SALKOWSKI, and their pupils. The products which are formed in the 

 putrefaction of proteins are (in addition to proteases, peptones, amino- 

 acids, and ammonia) indol, skatol, paracresol, phenol, phenylpropionic 

 acid, and phenylacetic acid, also paraoxyphenylacetic acid and hydro- 

 paracoumaric acid (besides paracresol, produced in the putrefaction of 

 tyrosin), volatile fatty acids, carbon dioxide, hydrogen, marsh-gas, methyl- 

 m,ercaptan, and sulphuretted hydrogen. In the putrefaction of gelatin 

 neither tyrosine nor indol is formed, while glycocoll is produced instead. 



Among these products of decomposition a few are of special interest 

 because of their behavior within the organism and because after their 

 absorption they pass into the urine. A few, such as the oxy acids, pass 

 unchanged into the urine. Others, such as phenols , are directly trans- 

 formed into ethereal sulphuric acids by synthesis, and are eliminated as 

 such by the urine; on the contrary, others, such as indol and skatol, are 

 converted into ethereal sulphuric acids after oxidation only (for details 

 see Chapter XV). The quantity of these bodies in the urine also varies 

 with the extent of the putrefactive processes in the intestine; at least 



1 Zeitschr. f. physiol. Chem., 55 and 58. 3 Zeitschr. f. physiol. Chem., 49 and 53. 



2 Ibid., 49. 4 Ibid., 56. 



