CHK.MICAL I'.ASIS OF THK ANIMAL BODY. 161 



any purely chemical means from the products of the 



ti< in of proteids. 



older statements of I'>. : hanip and Hitter that urea may be ob- 

 tained from pi-oteid.s by the action of j>t:iimu permanganate have 

 Keen shown to In- erroneous. 1 It is at nio>t pOMiblfl that a trace of 

 ^uaiiiilin may he funned, ami ^uanadin can hy the act inn of water be 

 ci.nverteil into urea ami ammonia: NH.C(NH 2 ).,-J-H^Oss:(lJ(^) t OO 

 -f-NHj. a Divch>el has however obtained from among the product> of 

 tin- decom|Mition of casein with concentrated boiling hydrochloric 

 aciil ami chloride of zinc a base to which lie has given the name of 

 l\-atiii.' When boiled with haryta water in excess it yields urea. 3 



What knowledge have we of the possible or probable form un- 

 der which the nitrogen may make its primary exit from the 

 muscles > The connection of muscle-kreatiu with urea-formation 

 has IMM-II already discussed ( 484, 485) and the evidence of the 

 connection may be briefly summed up as follows. A considerable 

 amount of kivatin exists (?) in the muscles at any one time, hence 

 probably a considerable amount is continuously being formed; 

 tlp-iv is no evidence that any of this kivatin leaves the body as 

 Mich, hence. it is presumably converted into some other substance 

 befoiv being discharged, and this other substance is probably urea, 



ing that kreatin may be readily decomposed into urea and 

 sarkosiu. Tln-iv are further reasons for supposing that the nitro- 



: leaves tin- muscles as a compound containing comparatively 

 little carbon, and kivatin answers to this requirement, since it 

 contains only four atoms of carbon to three of nitrogen. 4 If thi> 

 latter view be correct it implies that the nitrogen is not split off 

 in the form of amido-acids, since there is not sufficient carbon in 

 proteids to convert their nitrogen into the amido-acids with which 

 \\e have t<. deal iii the body. On the other hand when these 

 amido-acids (olycjii. leiiein, aspartic acid and asparnoin ) are in- 

 troduced into the body they are partly converted into urea, so that 

 if formed they would account for a portion at least of the urea 

 ted 



When pioteid- are decomposed by caustic alkalis, more espe- 

 cially baryta, or during putrefaction, they yield much ammonium 

 carbonate, which by simple dehydration would give nn-a. Xow 

 although ammonium carbonate, like many other salts of this base, 

 is readily converted into urea when administered to man or other 

 animals, there is no evidence, although it is a possibility, that the 

 nitrogen leaves the tissues as ammonium carbonate. 



1 Lww. .In. f. jmdt. r/,rm. (2) IM. ii. (1870). S. 289. Tappcincr, A'tfn. t&cht. 

 GettU. d. \\'i*. 1871. See Abut, in Malv -71, S. II. 



* LdWeil, Ann. <l. Cli-in. u. I'lmrm. l\-l. c< I. (1S^' 



./ ,1. rhem. Getell. 1890, S. 3096. Cf. Arch. f. I'hi/iiol. Jahrg. 1891, S. 

 254 et ueq. 



4 Munge, loc. cit. pp. 320, 328. 



11 



