INTESTINAL GASES. 493 



this is true for the ethereal sulphuric acids. Their quantity increases 

 in the urine with a stronger putrefaction, and the reverse takes place, 

 namely, a disappearance from the urine, or a great reduction in quantity,, 

 as BAUMANN, HARLEY and GOODBODY l have shown by experiments on 

 dogs, when the intestine is disinfected by various agents. 



The gases which are produced by the decomposition processes are 

 mixed in the intestinal tract with the atmospheric air swallowed with 

 the saliva and food, and as the gas developed in the decomposition of 

 different foods varies, so the mixture of gases after various foods should 

 have a dissimilar composition. This is found to be true. Oxygen is. 

 found only in very faint traces in the intestine; this may be accounted 

 for in part by the formation of reducing substances in the fermenta- 

 tion processes which combine with the oxygen, and partly, perhaps 

 chiefly, to a diffusion of the oxygen through the tissues of the walls of 

 the intestine. To show that these processes take place mainly in the 

 stomach the reader is referred to page 461, on the composition of the 

 gases of the stomach. Nitrogen is invariably found in the intestine, 

 and it is probably due chiefly to the swallowed air. The carbon dioxide 

 originates partly from the contents of the stomach, partly from the 

 putrefaction of the proteins, partly from the lactic-acid and butyric- 

 acid fermentation of carbohydrates, and partly from the setting free of 

 carbon dioxide from the alkali carbonates of the pancreatic and intes- 

 tinal juices by their neutralization through the hydrochloric acid of 

 the gastric juice and by organic acids formed in the fermentation. Hydro- 

 gen occurs in largest quantities after a milk diet, and in smallest quan- 

 tities after a purely meat diet. This gas seems to be formed chiefly in 

 the butyric-acid fermentation of carbohydrates, although it may occur 

 in large quantities in the putrefaction of proteins under certain circum- 

 stances. There is no doubt that the methylmercaptan and sulphuretted 

 hydrogen which occur normally in the intestine originate from the pro- 

 teins. The marsh-gas undoubtedly originates in the putrefaction of 

 proteins. As proof of this HUGE 2 found 26.45 per cent marsh-gas in 

 the human intestine after a meat diet. He found a still greater quan- 

 tity of this gas after a vegetable (leguminous) diet ; this coincides with the 

 observation that marsh-gas may be produced by a fermentation of car- 

 bohydrates, but especially of cellulose (TAPPEiNER 3 ). 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 arise from the decomposi- 

 tion of lecithin (HASEBROEK 4 ). 



1 Baumann, Zeitschr. f. physiol. Chem., 10; Harley and Goodbody, Brit. Med. 

 Journ., 1899. 



2 Wien. Sitzungsber., 44. 



3 Zeitschr. f. Biologie, 20 and 24. 4 Zeitschr. f. physiol. Chem., 12. 



