CHAP. IX.] THE CONTRACTILE TISSUES. 333 



From this decomposition it would appear not improbable that car- 

 nine is one of the intermediate products between the proteid mole- 

 cule and bodies belonging to the uric acid group. 



Uric acid. C 5 H 4 N 4 3 . 



It is most questionable whether uric acid exists in muscle; by 

 Meissner it has been fouud in traces in the muscles of fowls 1 . 



Urea. CH 4 N 2 0. 



It is yet doubtful whether urea should be reckoned amongst the 

 constituents of normal muscle. Liebig came to the conclusion that 

 it did not occur in that tissue, and this opinion has been generally 

 entertained. Of late Picard 2 has stated that the muscular tissue of 

 rabbits contains as much as 3 per cent, of urea. This statement is 

 entirely without foundation, Picard having by the method of analysis 

 which he employed reckoned other bodies, and especially creatine, as 

 urea. It is probable that muscle does contain an exceedingly small 

 quantity of urea, though its separation from the other nitrogenous 

 constituents offers peculiar difficulties. 



Inosinic acid. C 10 II 14 N 4 O n . 



By this name Liebig 3 designated a syrupy acid which he believed 

 to be a distinct proximate principle of muscle, though present in 

 extremely small quantity. With bases this acid is said to form 

 crystallizable salts. A fresh investigation is needed even to establish 

 the existence of this body. 



Taurine. C 2 H 7 NS0 3 . 



This body has been found in the muscles of the horse by Lim- 

 pricht 4 and Jacobsen 5 , and in those of fishes by Limpricht. It is, 

 according to Valenciennes and Fremy, found in the muscles of 

 molluscs. 



NON-NITROGENOUS ORGANIC CONSTITUENTS OF MUSCLE. 



Living muscle contains in addition to the previously described 

 nitrogenous organic constituents, considerable quantities of non-nitro- 

 genous organic bodies ; these are fats, glycogen, dextrin (?), inosit, 

 and perhaps small quantities of a fermentable sugar. 



1 Meissner, Zcitschr. f. rat. Med. Vol. xxxi. (1868) p. 144. 



2 Picard, Comptes Eendus, Vol. LXXXVII. (1878) No. 15 and 25. 



3 Liebig, Ann. d. Chem. u. PJiarm. Vol. LXXII. (1847) p. 317. 



4 Limpricht, Ann. d. Chem. u. Pharm. Vol. cxxxm. (1865) p. 293. 

 6 Jacobsen, ibid. Vol. CLVII. (1871) p. 227. 



