494 DIGESTION. 



Putrefaction in the intestine not only depends upon the composi- 

 tion of the food, but also upon the albuminous secretions and the bile. 

 Among the constituents of bile which are changed or decomposed there 

 are not only the pigments the bilirubin yields urobilin and a brown 

 pigment but also the bile-acids, especially taurocholic acid. Glyco- 

 cholic acid is more stable, and a part is found unchanged in the excrement 

 of certain animals, while taurocholic acid is so completely decomposed 

 that it is entirely absent in the feces. In the fetus, on the contrary, 

 in whose intestinal tract no putrefaction processes occur, undecomposed 

 bile-acids and bile-pigments are found in the contents of the intestine. 

 The transformation of bilirubin into urobilin does not occur, as previously 

 stated, in the small, but in the large intestine in man. 



As under normal conditions no putrefaction, or at least none worth 

 mentioning, occurs in the small intestine, and as often nearly all the pro- 

 tein of the food is absorbed, it follows that ordinarily it is the secretions 

 and cells rich in proteins which undergo putrefaction. That the secre- 

 tions rich in proteins are destroyed in putrefaction in the intestine follows 

 from the fact that putrefaction may also continue during complete fasting. 

 From the observations of M TILLER* upon CETTI it was found that the 

 elimination of indican during starvation rapidly decreased and after the 

 third day of starvation it had entirely disappeared, while the phenol 

 elimination, which at first decreased so that it was nearly minimum, 

 increased again from the fifth day of starvation, and on the eighth or 

 ninth day it was three to seven times as much as in man under ordinary 

 circumstances. In dogs, on the contrary, the elimination of indican 

 during starvation is considerable, but the phe"nol elimination is slight. 

 Among the secretions which undergo putrefaction in the intestine, the 

 pancreatic juice, which putrefies most readily, takes first place. 



From the foregoing facts it must be concluded that the products 

 formed by the putrefaction in the intestine are in part the same as those 

 formed in digestion. The putrefaction may be of benefit to the organism 

 in so far as the formation of such products as proteoses, peptones, poly- 

 peptides and amino-acids is concerned. The question has indeed been 

 asked (PASTEUR), is digestion possible without micro-organisms? NUTT Al- 

 and THIERFELDER have shown that guinea-pigs, removed from the uterus 

 of the mother by CaBsarian section, could with sterile air digest well and 

 assimilate sterile food (milk and crackers) in the complete absence of 

 bacteria in the intestine, and developed normally and increased in weight. 

 SCHOTTELIUS 2 has arrived at other results by experiments with hens. 

 The chickens, hatched under sterile conditions, kept in sterile rooms and 



1 Berlin, klin. Wochenschr., 1887. 



2 Nuttal and Thierfelder, Zeitschr. f. physiol. Chem., 21 and 22, Schottelius, Arch, 

 f. Hygiene, 34, 42, and 67. 



