70 ENZYMES OK SOLUBLE FERMENTS. 



enzyme employed, and is not, so far as we know, used up in the 

 change which it induces, since it is present in serum 



Muscle enzyme. 



The phenomena of the clotting of muscle-plasma compared with 

 those of blood-plasma and the relationship of the process to the 

 presence of neutral salts and to temperature suggest at once that 

 the change is probably one in which some enzyme plays a part. 

 Immediately after Schmidt's discovery of the fibrin-ferment the 

 question of the existence of a rnyosin-ferment was investigated 

 under his guidance, 1 and resulted in the discovery of the exist- 

 ence in muscles of an enzyme which appeared to be identical 

 with fibrin-ferment rather than specifically myosinic. The later 

 work of the Dorpat School further confirmed the above, but failed 

 to establish the existence of an enzyme, differing from fibrin-fer- 

 ment and specifically active in promoting the clotting of muscle- 

 plasma. 2 More recently it has been shown that by applying 

 Schmidt's method to muscles which have been treated for some 

 time with alcohol, a solution may be obtained which hastens the 

 clotting of diluted muscle-plasma, does not facilitate the forma- 

 tion of fibrin in blood-plasma, and, unlike fibrin-ferment, requires 

 to be heated to 100 before it loses its activity. 3 The active 

 agent in the solution is therefore not identical with fibrin-ferment 

 and may be spoken of as a myosin-ferment. 



Urea-ferment. 



When urine is exposed to the air its acidity at first increases, 

 but in most cases this speedily gives way to a marked alkalinity, 

 which is accompanied by the evolution of ammonia. This is due 

 to a hydrolytic fermentative change resulting from the appear- 

 ance and development in the urine of certain micro-organisms of 

 which the best known is the Torula ureae. 4 Normally urine is 

 free from these organisms and may be kept in the excised blad- 

 der for an indefinite period without exhibiting any tendency to 

 become alkaline ; 5 in certain abnormal conditions it may undergo 

 an active alkaline fermentation while still in the bladder. The 

 part played by the organisms was for a long time regarded as 

 similar to that of yeast-cells in promoting alcoholic fermentation. 

 Soon however evidence was adduced which showed that the 



1 Michelson, Dlss. Dorpat, 1872. 



2 Grubert, Diss. Dorpat, 1883. Klemptner, Ibid. Kugler, Ibid. 

 8 Halliburton, Jl. of Physiol. Vol. vin. (1887), p. 159. 



* Midler, Jn. f. prakt. Chem. Bd. LXXXI. (1860), S. 467. Pasteur, Compt. Rend. 

 T. L. 1860, p. 869. van Tieghem, Ibid. T. LVIII. 1864, p. 210. But see also Jaksch, 

 Zt. f. physiol. Chem. Bd. v. (1881), S. 395. Leube, Virchow's Arch. Bd. c. (1885), 

 S. 540. Miquel, Bull, de la Soc. Chim. T. xxix. (1878), p. 387 ; xxxi. p. 391 ; 

 xxxii. (1879), p. 126. 



'" Cazeneuve et Livon, Compt. Rend. T. i.xxxv. (1877), p. 571. Bull, de la Soc. 

 Chim. T. xxvni. (1877), p. 484. 



