PROTEIN DIGESTION IN THE INTESTINE. 491 



brown, due to bilirubin, and had an acid reaction which, on a mixed 

 but chiefly animal diet, calculated as acetic acid, amounted to 1 p. m. 

 The contents were nearly odorless, having an empyreumatic odor recall- 

 ing that of volatile fatty acids, and infrequently had a putrid odor resemb- 

 ling that of indol. The essential acid present was acetic acid, accom- 

 panied by fermentation and paralactic acid, volatile fatty acids, succinic 

 acid, and bile-acids. Coagulable proteins, peptone, mucin, dextrin, dex- 

 trose, and alcohol were present. Leucine and tyrosine could not be 

 detected. 



According to the above-mentioned investigators, the proteins are 

 only to a very slight extent, if at all, decomposed by the microbes in the 

 small intestine of man. The organisms present in the small intestine 

 preferably decompose the carbohydrates, forming ethyl alcohol and the 

 above-mentioned organic acids. 



Further investigations of JAKOWSKY and of AD. SCHMIDT l lead to 

 the same result, namely, that in man the putrefaction of the proteins 

 takes place chiefly in the large intestine, and the conditions are the same 

 in carnivora. In these latter it has been possible to follow the intestinal 

 digestion by investigating the contents of the various parts of the intestine 

 as well as by forming fistulas along the intestine. Again PAWLOW and 

 his pupils, especially LONDON 2 and his collaborators, have essentially 

 advanced our knowledge on this subject. 



In regard to the digestion of protein it has been found that after 

 feeding meat, bread or certain protein bodies, the digestion in the 

 stomach and small intestine is so complete that on the passage of 

 the contents into the caBcum all the protein is digested and absorbed. 

 Unboiled white of egg is an exception and is digested with difficulty. 

 In experiments with unboiled white of egg LONDON and SULEIMA 3 

 reobtained 73 per cent of the coagulable protein from a fistula in the 

 ileum (2-3 cm. in front of the caecum). KUTSCHER and SEEMANN, 

 ABDERHALDEN, LONDON and collaborators 4 have also found that non- 

 biuret giving products and amino-acids are regularly split off, probably 

 by the combined action of trypsin and erepsin. These amino-acids 

 occur to a slight extent only, but from this no conclusion can be drawn 

 as to the extent of amino-acid formation, because we do not know 

 the extent of their absorption. The digestion of protein in the intestine, 



1 Jakowsky, Arch, des scienc. biol. de St. Pe"tersbourg, 1; Ad. Schmidt, Arch. f. 

 Verdauunskr., 4. 



2 The works of London and collaborators cannot be cited in detail, but may be 

 found in Zeitschr. f. physiol. Chem., 46-57. 



3 Zeitschr. f. physiol. Chem.. 46. 



4 Kutscher and Seemann, ibid., 34; Abderhalden and London, with Kautzsch, 

 ibid., with L. Baumann, ibid., 51, with v. Korosy, ibid., 53. 



