DIGESTION. 219 



greater quantity of this gas after a diet consisting of leguminous 

 plants; this coinsides with the observation that marsh-gas may be 

 produced by a fermentation of carbohydrates, but especially of cel- 

 lulose (HOPPE-SEYLER, TAPPENIER). Such an origin of marsh- 

 gas, especially in herbivora, is to be expected. A small part of the 

 marsh-gas and carbon dioxide may also depend on the decomposition 

 of lecithin (HASEBROEK). 



Putrefaction in the intestine not only depends upon the com- 

 position of the food, but also upon the albuminous secretions and 

 the bile. Among the constituents of bile which are changed or 

 decomposed, we have not only the pigments produced from the 

 bilirubin, as is generally assumed, hydrobilirubin and brown pig- 

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

 cholic acid is more stable and a part is found unchanged in the ex- 

 crement of certain animals, while taurocholic acid is so completely 

 decomposed that it is entirely absent in the faeces. In the foetus, 

 in whose intestinal tract no putrefaction processes occur, we find, 

 on the contrary, undecomposed bile-acids and bile-pigments in the 

 contents of the intestine. That the secretion rich in albumin is 

 an important element in putrefaction in the intestine follows from 

 the fact that putrefaction may also continue during fasting. From 

 the observations of MULLER on CETTI it was found that the elimi- 

 nation of indican during hunger 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 elimi- 

 nation of indican during starvation is considerable, but the phenol 

 elimination is minimum. Among the secretions which undergo 

 putrefaction in the intestine, the pancreatic juice, which putrifies 

 most readily, takes first place. PISENTI found, in his experiments 

 on dogs, that the elimination of indican by the urine greatly 

 diminished after tying the pancreatic passages, but that it increased 

 again when the animal was given pancreas peptones or pancreatic 

 juice. 



From the foregoing facts we conclude that the products formed 

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



