THE EXTRACTIVES OF MUSCLE. 



101 



this means Johnson showed that creatinine (a different creatinine from 

 urinary creatinine) is more abundant in muscle than creatine, which 

 is usually almost entirely absent. This unexpected result has been 

 confirmed by Kemmerich. 1 Creatinine is readily changed into creatine 

 by the action of putrefactive micro-organisms. 



Xanthocreatinine (C 5 H 10 N 4 0), crusocreatinine (C 5 H 8 N 4 0), ampliicrea- 

 tine (C H 19 N 7 4 ), and pseudoxantJiine (C 4 H 5 N 5 0) are leucomaines stated 

 by Gautier 2 to be present in small quantities. 



Xanthine, hypoxanthine, and uric acid are found in small quantities 

 only; the numbers given are as follows: xanthine, O0026 per cent.; 3 

 hypoxanthine, 0'022-0'026 ; 4 uric acid, traces. 5 Uric acid is more 

 abundant in the muscles of reptiles (alligators). The crystalline forms 

 of some of the compounds of xanthine 

 and hypoxanthine are given in Fig. 17. 



Car nine is a crystalline base 

 (C T H 8 N 4 ;! +H 2 0), originally found by 

 Weidel 6 in large quantities (1 per 

 cent.) in American meat extracts, but 

 since found in the flesh of many 

 animals. 7 It is probably closely re- 

 lated to the members of the uric acid 

 group just mentioned. 



Urea. It is generally stated that 

 muscle contains little or no urea. 

 This statement is chiefly due to the 

 fact that it was until recently a 

 matter of difficulty to separate 

 urea, when only present in small 

 quantities, from other nitrogenous bases. In some animals, however, 

 the muscular tissue contains a fairly large amount of urea. This is 

 the case with the muscles of arthropods. 8 Stadeler and Frerichs 9 

 were the first to discover that the organs, including the muscles, 

 of Selachian fishes are rich in urea. This was confirmed in the case 

 of Selachian embryos by Krukenberg, 10 and more recently in the 

 adult animals by Schroder. 11 In two varieties of dog-fish, the 

 mean percentage of urea in the blood was 2*61, in muscle 1/95, and 

 in liver 1-36. Schrceder explains this by the fact that the kidneys are 

 sluggish in these animals. By a new method, Schondorff 12 has been 

 able to satisfactorily establish the existence of a small quantity of 

 urea in the muscles of mammals; Kaufmann 13 gives the percentage 



1 Kemmerich, Ztschr. f. physiol. Chem., Strassburg, 1894, Bd. xviii. S. 409. 



2 Jahresb. u. d. Fortsc.hr. d. Thier-Chem., Wiesbaden, Bd. xxii. S. 335. 



3 Scherer, Ann. d. Chem., Leipzig, Bd. cvii. S. 314. 

 JNeubatier, Ztschr. f. anal. Chem., Wiesbaden, Bd. vi. S. 33. 



5 Meissner, Ztschr. f. rat. Med., Leipzig, Bd. xxxi. p. 144. 



6 Ann. d. Chem., Leipzig, Bd. clviii. S. 353. 



7 Krukenberg and Wagner, Sitzungsb. d. phys.-mcd. Gfesellsch. zu IVurzburg, 1883, No. 4. 

 See also Jahresb. u. d. Fortschr. d. Thier-Chem., Wiesbaden, Bd. xi. S. 340. 



8 Krukenberg, -'(Inter such. a. d. physiol. Inst. d. Univ. Heidelberg, 1881, Bd. iv. S. 33 ; 

 "Vergleich. pliysiol. Vortrage," 1886J S. 313. 



9 Journ. f. prakt. Cham., Leipzig, 1858, Bd. Ixxiii. S. 48 ; ibid., Bd. Ixxvi. S. 58. 



10 "Vergleich. pliysiol. Vortrage,'" 1886, S. 314. 



11 Ztschr. f. physiol. Chem., Strassburg, 1890, Bd. xiv. S. 576 ; Krukenberg, Centralbl. 

 f. d. med. Wissensch.. Berlin, 1887. No. *25. 



12 Arch.f. d. ges. Physiol. ,Bonn , 1 895, Bd. Ixii. S. 332. For tbe method employed, see ibid. , S. 1 



13 Arch, dc physiol. norm,, ctpath., Paris, Se"r. 5, tome vi. 



FIG. 15. Creatine-zinc chloride crystals. 

 After Klihne. 



