CLASSIFICATION 465 



I. The constituents of the digestive secretions, including 

 the bile salts and pigments, pepsin, and trypsin. 

 II. Products of normal digestion : 



(a) From proteids proteoses, peptones, amino-acids. 

 (6) From fats fatty acids and glycerin. 

 III. Products of putrefaction and fermentation : 

 (a) From proteids : 



(1) From the aromatic radicals (tyrosin, phenylalanin, 



tryptophan) indol, skatol, skatol carbonic (or 

 indol acetic) acid, phenol, cresol, dioxyphenols. 



(2) From the fatty acid radicals fatty acids (especially 



butyric and acetic), acetone, ammonia, amino- 

 acids, carbon dioxide, hydrogen, marsh-gas. Also 

 ptomai'ns : cadaverin, putrescin, ethylidendiamin. 



(3) From the sulphur-containing radicals H 2 S, 



methyl mercaptan, ethyl mercaptan, ethyl sulphid. 

 (6) From carbohydrates : 



Fatty acids, the following having been detected 

 formic, acetic, propionic, butyric, valerian ic, 

 lactic, oxybutyric, and succinic; also acetone, 

 C0 2 , CH 4 , H 2 . 

 (c) From fats : 



Higher fatty acids, as well as butyric acid ; also 

 glycerin. From lecithin cholin, neurin, and 

 muscarin-like bodies. 



IV. Synthetic products of bacterial activity (e. g. botulismus) 

 which cannot properly be considered as causing " autointoxi- 

 cation." 



L THE CONSTITUENTS OF THE DIGESTIVE FLUIDS 



These call for but brief consideration, for, although many of 

 them are known to be toxic, yet there is no evidence that they 

 cause autointoxication, either in health or disease. Both pepsin 

 and trypsin, especially the latter, are decidedly toxic when in- 

 jected experimentally into the blood (see Enzymes, pp. 7775), 

 but they do not appear ever to pass through the intestinal wall 

 in sufficient quantity to cause harm, although minute traces may 

 appear in the urine ; this harmlessness probably depends largely 

 on the known inhibiting action of the blood upon enzymes. 



The bile salts are also toxic, especially hemolytic, but those 

 that are reabsorbed from the intestines are taken back into the 

 liver and reexcreted. This protective arrangement seems to be 

 sufficient for all emergencies. The bile-pigments become con- 

 verted into hydrobilirubin through reduction, and this is largely 



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