CHEMICAL BASIS OF THE ANIMAL BODY. 1251 



nitrate of silver, C 6 H 13 N 3 O 2 . HNO 3 + AgNO 3 . 

 empirical formula is seen to be that of a homolc 



From this its 

 lomologue of creatine, 



but there is some doubt as to whether one molecule of water 

 should not be subtracted from the above, in which case it would 

 be homologous with creatinine (C 4 H 7 N 3 O 2 ) and receive the 

 name lysatinine (C 6 H n N 3 O 2 ). 



Lysatine may also be found among the products, similarly 

 obtained, of the decomposition of gelatin, keratin and elastin, 

 in the latter case unaccompanied by lysine, and in considerable 

 amount from the products of a pancreatic digestion of fibrin. 

 Its production in the latter case is important as a preliminary 

 to the most interesting fact regarding lysatine which must now 

 be stated. It has already been said (p. 1247) that when creatine 

 is boiled in baryta-water it is split up into sarcosine and urea. 

 Now it is found that when lysatine is similarly treated it also 

 yields urea as a product of its decomposition, so that in this way 

 it has become possible for the first time to obtain urea from pro- 

 teids by a decomposition not involving oxidation, and thus an 

 endeavour often made in the past has at last been realized. 

 Apart from the more purely theoretical interest of this result it 

 is at once seen that we have here a possible source of some of 

 the urea which leaves the body. 



A crystalline product of the decomposition of at first keratin 

 and subsequently gelatin, egg-albumin and casein has recently been 

 described under the name of arginine (C 6 H 14 N 4 2 ). 



AMIDOACIDS OF THE LACTIC SERIES. 



Cystine. (C 3 H 6 NSO 2 ) 2 . 

 (Amido-sulpholactic acid.) 



[S . C(CH 3 ) (NH 2 ) . COOH] 2 . 



FIG. 207. CYSTIXE CRYSTALS. (After Funke.) 



Is the chief constituent of a rarely occurring urinary calcu- 

 lus in men and dogs. It may also occur in renal concretions, 



