76 KAKTTAL OF CATTLE-FEEDIKa 



Of the albuminoids, it contains albumin^ and blood-fibrin 

 or at least one constituent of it ; it also contains some fat, 

 nsiiall J traces of sugar thougli nc\ er lai^ge quantities of it, 

 and a considerable proportion of mineral matters, espe- 

 cially of soda salts and clilorides, besides minute traces of 

 various otber substances. 



Coagulation. — So long as tlie blood remains in the ves- 

 sels of the living body it continues fluid, even if its circu- 

 lation be stopped, but wlien drawn from the body it co- 

 agulates after standing for a time, yielding a yellowisli 

 liquid, tlie serurrbj and blood-fibrin. At ordinary temper- 

 atures the change takes place rapidly, but only slowly at a 

 low temperature; it is entirely liindeied by addition to the 

 blood of a strong solution of sulphate of soda, sulphate of 

 magnesia, nitrate of soda, common salt, and other sub- 

 stances. Opinions differ as to the nature of the coagula- 

 tion, but it is certain that the blood-fibrin does not exist 

 as such in the blood but is f oi-med from a substance called 

 JThrinogen^ contained in the plasma, and concerning which 

 tliree facts may be consideied as established : 1st. Fibrin 

 is only formed in fluids which contain fibrinogen. 2d. A 

 solution of fibrinogen alone yields no fibrin, and hence 

 tlie action of some other body or bodies is requisite. 3d. 

 This other body or bodies is yielded by the colorless 

 corpuscles. 



A. Schmidt, who has most fully investigated this sub- 

 ject, regards the substances coming from the colorless cor- 

 pi|<@des as partaking of the nature of a ferment, and be- 

 lieves that they are not contained in the living blood but 

 are formed, after the blood is drawn from the body, by the 

 decomposition of the coi*puscles. Whether this be true or 

 not, there is no doubt that these corpuscles yield a sub- 

 stance capable of converting fibrinogen into fibrin. 



