INDOLE AND INDICAN 581 



able is too siiiull to coiubine with all the aromatic railicals cntcrinK the 

 blood, a large amount of the glycuronic acid compound appears in the 

 urine {e. g., after therapeutic administration of phenol, cre.sol, thymol, 

 (iamphor, etc.)- Both the preliminar\' oxidation and the cond:)ininK 

 with acids seem to occur chieHy in the liver, this process constitutinjj; 

 one of the most important of the many protective offites of that organ, 

 since the resulting compounds are much less toxic than are the original 

 substances. ^^ Herter and '\Vakeman^"have shown that living cells have 

 the power of acting upon indole and phenol (and presumably upon the 

 rest of this group) in such a way that they cannot be recovered by dis- 

 tillation. Most active in this respect is the liver, then in order come 

 kidney, muscle, blood, and brain. The change seems to be a loose 

 chemical combination with the protoplasm of the cells, and the power 

 of the tissues to bring about this combination is not greatly decreased 

 by serious pathological changes in the organs (e. g., ricin poisoning). ^^ 

 Indole. — This is probably the most important member of this 

 group of substances, the striking color of its derivatives making its 

 detection in the urine easy, so that it is generally used as the most 

 available index of the amount of putrefaction that is occurring in the 

 intestines. ^^ The greatest quantities are found when intestinal putre- 

 faction is marked, especially in intestinal obstruction involving the 

 small intestine; obstruction of the large intestine, as Jaffe first demon- 

 strated, does not cause marked indicanuria unless the stagnation 

 involves the ileum, as it may in the later stages of obstruction. With 

 marked impairment of renal function indican may accumulate in the 

 blood (see Uremia). There can be no question that the indican of the 

 urine is derived, at least in part, from the indole formed in the intes- 

 tine, for administration of indole by mouth to either animals or man 

 causes a considerable increase in the indican present in the urine; 

 however, but 40 to 60 per cent, can be recovered in this way, the rest 

 apparently being oxidized to other compounds, part of which may also 

 appear in the urine. ^^ Whether part of the urinarj^ indican is derived 

 from tryptophane liberated during intracellular protein metabolism, 

 and not from intestinal putrefaction, has long been a disputed 

 point among physiological chemists.^"* The demonstration by Ellinger 

 and Gentzen^^ that tr3^p':ophane, when fed or injected subcutaneously, 

 causes no increase in urinary indican, whereas its injection into the 

 cecum causes much indicanuria, w-ould indicate that indole is formed 



-^ Metchnikoff insisted that these sulfo-compounds still retain considerable 

 toxicity. (Ann. Inst. Pasteur, 1914 (27), S93). 



3" Jour. Exper. Med., 1899 (4), 307. 



" For further discussion of this topic, see "Chemical Defences against Poisons 

 of Known Composition," Chapter x. 



32 See Houghton, Amer. Jour. Med. Sci.. 190S (135), 567. 



3' If gelatin is substituted for proteins in the dietary, indican is not excreted, 

 because gelatin does not contain tryptophane (Underbill, Amer. Jour. Phvsiol., 

 1904 (12), 176). 



'* Literature bv Gerhardt, Ergeb. der Phvsiol.. 1904 (III, Abt. I), 131. 



" Hofmeister's Beitr., 1903 (4), 171. 



