CHEMICAL BASIS OF THK ANIMAL BODY. 163 



found in fern 'cyanide of potassium, prepared l>y fu.-in^ nitron-nous 

 animal refu.-e \\itli potassium carhonate and iron. Then- i> further 

 evidence of tin- existence in the body i.f cyanic re-idiies, as shown by the 

 exit fn'in it of SulphocyUMtee (HCNS), \vliich an- found in both saliva 

 and mure part icularly in urine. 1 Tin- existence ..f sulphur in the>e 

 salts -U^I-M.-. at once that it ari-e> fn-m the decomposition Off proteid.-, 

 into wh<.x- compo>ition sulphur enters as a constant and charaeteri-t ic 

 constituent. The formation of ralphocjUUC acid in the body has 

 recently Keen investigated, and it i* worthy of note that it i> stated 

 ur in the uriiu- only nf those animals \\hich excrete their nitro- 

 gen chiefly in the form of urea. 2 



The various ways by wliich it has l>een suggested that urea may 

 arise in the body all imply that whatever be the form in which 

 the nitrogen initially leaves the tissues, the substance or sub- 

 stances in which it makes its exit undergo their final (synthetic?) 

 eon version in some other organ of the body. In the case of leucin 

 then- i> distinct evidence that the conversion is effected in the 

 liver, and there is increasing evidence that this organ is largely 

 concerned in the presumably synthetic changes which lead to the 

 formation of urea in mammals and of uric acid in birds. Thus 

 Schroder has shown that the conversion of ammonium carbonate 

 into urea occurs in the liver, 3 and a similar relationship to the 

 formation of uric acid in liinls has additionally been proved* 

 Further there are many observations which show, when the liver 

 is diseased, a marked diminution in the excretion of urea, with a 

 frequently increased output of ammonia. 6 After extirpation of 

 the liver in birds tin- urine contains not only more ammonia but 

 a larjre amount of sarcolactic acid. It would lie however prema- 

 ture tn regard this fact as showing that in birds uric acid is partly 

 formed l.y the converting activity of the liver brought to bear 

 Upon ammonia and lactic acid. When urea is given to birds it 

 reappears externally as uric acid, 7 but this change is not effected 

 after extirpation of the liver. 



Xit/i.tfifitfri/ t'l-i-ua. The hydrogen atoms of urea can he replaced 

 hy alcohol- and acid-radicle-. The results an- >ul.st it uted un-a* in the 

 .ise. or iin-ides as they are called in the. second, when the h\dro- 

 U'en i> replaced l.y the radicle of an acid. Many of them are called 

 acids, -ince the hydrogen from the amido ^n>up. if not all replaced as 

 al.ove, can be replaced by a metal. Tims the snl.-t itution of oxalyl 



1 Munk. Yin-how's Arrh. Bd. LXIX. (IsTT), S 354. Gscheidlen, Pfliiger'a Arch. 

 !',.! or. (1-:: . s. 401. 



8 Hruylants, Bull. iif I'acad. dr mf<\. ,lc lifl^/nf, (4) T. u. (1888), p. 18 et tea. 



/'.ill,, n. ri.mm. 11.1. \v. (I I ; 1J.I. \IX. (1885), b. 373. 



S.il.-iiK.n, Yin-liuw's A, '/,. 15,1. \. vn 141 



* MinkowMki. Arch. f. er,,. /',//<. H. /'luirm. IM. XXI. (!' 



6 Koster, IM SptrmtHtaU^T. xi.iv. (iWT'.i), j.. i.vr llall.-rv..nl.'ii. .-lt,-/i. 

 r<ith. i/. I'harm. Ikl. xn. (1880), S. 'J.-J7. Stadelmann, Deuttch. Arch. f. Uin. Ml. 

 I?.!. \\MII I!--.-!). S. 526. 



Minkowski, loc. cit. See also Marctue, PflUger'n Arrh. R<1. xxxix. (1886), 8. 

 425. 



7 Meyer u. Jafft', Ber. d. d. ekem. Gttell. Bd. X. (1877), 8. I 



