THE DECOMPOSITION PRODUCTS OF PROTEIDS. 71 



Lossen, 1 who found that the substance Bechamp and others 

 had obtained was not urea, but guanidine, which is readily 

 mistaken for it. This guanidine might have originated 

 from small quantities of xanthine present as an impurity in 

 the egg-white employed, for xanthine on oxidation with 

 hydrochloric acid and potassium chlorate produces guanidine. 

 On the other hand Drechsel 2 points out that creatine is a 

 methyl-guanidine acetic acid and that when treated with 

 mercuric oxide it yields methyl guanidine ; and assuming 

 dysatinine to be a homologue of creatinine, the guanidine 

 obtained by Lossen may have come from that, and Drech- 

 sel hopes to be able, by treatment with mercuric oxide, 

 to obtain it from lysatinine. Drechsel is careful to 

 point out that the urea obtained by his method is not a 

 result of oxidation, but of hydration processes. The 

 stannous chloride effectively prevents oxidation, and, more- 

 over, the action of the barium hydrate on lysatinine is 

 again a hydration. 



The remaining products obtained from the lysatinine 

 have not yet been isolated. 



Drechsel, therefore, considers that one possible source 

 of urea as a result of proteid metabolism may be lysatinine. 

 But supposing that all the proteid assimilated yielded the 

 proportion of lysatinine, and then of urea, that he found in 

 his experiment in vitro, even then only about one ninth of 

 the total urea excreted will be accounted for. 



There is, however, another point which has not been 

 noticed, but which I think gives us a reason why we should 

 not expect to find urea among the decomposition products 

 of proteids. The whole of the knowledge we at present 

 possess tends to show that urea is not formed in those 

 positions in the body where proteid disintegration is occur- 

 ring, viz., the tissues, but that it is formed in one position 

 only, the liver, and there too mainly, if not exclusively, 

 from the very simplest nitrogenous bodies, ammonium 

 salts. Looked at from this point of view the series of 



1 Ann. Chem. Pharm., vol. 201, p. 369, 1880. 



2 Loc . cit. 



