ALBUMINS OR PROTEINS. 259 



It is produced by the decomposition of indoxylsulphuric and indoxyl- 

 glucuronic acids into their components, and the simultaneous oxidation of 

 the indoxyl to indigo-blue. This coloring matter occurs in the indigo 

 plant in the form of a glucoside, called indican. 1 Indigo-blue can occa- 

 sionally be observed on the surface of putrid urine as a copper-red scum, 

 with a metallic luster. There is also another coloring material present, 

 an isomer of indigo-blue. This is indirubin, indigo-red. This coloring 

 matter has also been assumed to be related to skatoxyl, although this 

 substance has not yet been isolated, as such from normal urine. This 

 question must be left open for the present. 



In the putrefaction of tryptophane, skatole acetic. acid and skatolecar- 

 boxylic acid are also produced. Up to the present time, only the latter 

 has been shown to be probably present in urine. 2 



Furthermore, cadaverine and putrescine are also to be mentioned among 

 the putrefactive products of the intestines. Cadaverine is formed with 

 loss of carbon dioxide from lysine (diaminocaproic acid) , and is a penta- 

 methylenediamine. 



CH 2 . CH 2 . CH 2 . CH 2 . CH . COOH=CH 2 . CH 2 . CH 2 . CH 2 . CH 2 + CO 2 

 NH 2 NH 2 NH 2 NH 2 



V -- y / V .y - / 



Lysine Cadaverine 



Putrescine, tetramethylenediamine, is produced from ornithine, diamino- 

 valeric acid, a constituent of arginine: 



CH 2 . CH 2 . CH 2 . CH . COOH=CH 2 . CH 2 . CH 2 . CH 2 + C0 2 



NH 2 NH 2 NH 2 NH 2 



Ornithine Putrescine 



Phenylethylamine is produced from phenylalanine : 



C 6 H 5 . CH 2 . CH (NH 2 ) . COOH=C 6 H 5 . CH 2 . CH 2 . NH 2 + CO 2 

 and hydroxyphenylethylamine from tyrosine: 



/ OH / OH 



C 6 H 4 = C 6 H 4 + C0 2 



x CH 2 . CH (NH 2 ) COOH x CH 2 . CH 2 . NH 2 



Recently 3 the attempt has been made to trace the production of phenyl- 

 ethylamine and of hydroxyphenylethylamine to the action of trypsin or 

 of pepsin. A great many experiments have been carried out, with pure 

 pancreatic and gastric juices, taking great care to prevent any bacterial 



1 The indoxyl of urine is also wrongly called indican. 



2 E. Salkowski: Z. physiol. Chem. 9, 1, 23 (1885). 



3 R. C. Emmerson: Hofmeister's Beit. 1, 501 (1902). 



