CHAP. IX.] THE CONTRACTILE TISSUES. 329 



Creatinine. C 4 H 7 N 3 0. 



This body, which is a strong base, and which, as has already been 

 stated, can be obtained from creatine by the prolonged action 

 of dilute acids or water, is according to Neubauer 1 and Nawrocki 2 

 not present in muscle. On the other hand, C. Voit believes it to be 

 occasionally present in that tissue. 



Creatinine forms with zinc chloride a sparingly soluble compound 

 having the composition represented by the formula (C 4 H ? N 3 O) 2 ZnCl 2 , 

 and it is by conversion into this compound that it is always 

 estimated. Creatinine will be treated of more fully in the Chapter 

 on Urine. 



Hypoxanthine or Sarcine. C 5 H 4 N 4 O. 



This body was first discovered by Scherer in the splenic pulp, but 

 was shewn by Strecker to be constantly present in muscle. Unlike 

 creatine, hypoxanthine is pretty widely distributed, being found in 

 the blood, in many glands, in the marrow of bones, &c. 



Prepara- The mother liquor from which creatine has sepa- 



tion. rated is diluted considerably with water, and ammonia 



is added until the reaction is alkaline; it is then treated with an 

 ammoniacal solution of silver nitrate, which throws down a flocculent, 

 gelatinous precipitate (C 5 H 2 Ag 2 N 4 0), which is allowed to subside, 

 and first washed by decantation with weak solution of ammonia, and 

 then collected on a filter. The precipitate is then boiled in nitric 

 acid of specific gravity 1*1, which dissolves the hypoxanthine com- 

 pound, leaving undissolved any silver chloride which may be mixed 

 with it. The latter is separated from the solution by decan- 

 tation. On cooling, the nitric acid deposits a white crystalline com- 

 pound of hypoxanthine and silver nitrate, having the composition 

 C 5 H 4 N 4 O . AgNO 3 ; these crystals often present the form of isolated 

 spindles or of rosettes formed of spindles radiating from a centre. 



The silver compound is suspended in water, and treated with 

 sulphuretted hydrogen, then heated ; the clear fluid filtered from the 

 precipitate of silver sulphide deposits, on concentration, crystals of 

 nitrate of hypoxanthine ; when this compound is dissolved in hot 

 water and treated with ammonia, it deposits crystalline nodules (never 

 needles) of hypoxanthine 8 . 



Pro erties " ^ e foregoing paragraph, hypoxanthine 



crystallizes in the form of nodules which never (Kiihne) 

 exhibit any needles. It is scantily soluble in alcohol; it is soluble in 



1 Neubauer, Zeitschr. f. anal Chemie, Vol. n. (1863) p. 22. 



2 Nawrocki, Centralbatt f. d. med. Wissensch. 1865, p. 417. Zeitschr. f. anal. Chemie, 

 1865, p. 336. 



3 Very admirable woodcuts exhibiting the crystalline forms of the compound 

 of hypoxanthine with silver nitrate and of nitrate of hypoxanthine, are to be found in 

 Kiilme's Lehrbuoh, etc. p. 295 and 296. 



