348 PROTEIN-COMPOUNDS. 



uncoagulated plasma, perceptibly accelerates the coagulation of the 

 fibrin ; but so simple an explanation is probably not admissible, and 

 it would rather seem that the serous exudations possess no tendency 

 to become organised, in consequence of their never being pure 

 plasma minus fibrin, but of their frequently containing less albu- 

 men, and in all cases more salts and extractive matters, than the 

 serum of the blood ; although we are unable to determine the 

 manner in which salts are able to arrest the metamorphosis of 

 albumen into cells, we yet know that other metamorphoses of 

 albumen, as for instance, putrefaction, are hindered or modified by 

 the agency of these bodies. 



FIBRIN. 

 Chemical Relations. 



Properties. We must distinguish between numerous modifi- 

 cations of fibrin, if we would attempt to specify the various sub- 

 stances to which this term has been applied. We purpose, there- 

 fore, only to consider fibrin, in the first place, in its naturally dis- 

 solved form ; next, in a spontaneous state of coagulation ; and, 

 lastly, when it is coagulated by heat, or boiled. 



In the natural solution of fibrin, we can distinguish only a few 

 of its properties, since it is here mixed with albumen and other 

 matters of the serum of the blood ; and we are acquainted with 

 few reagents by which to distinguish dissolved fibrin in filtered 

 frogs' blood (i. e. in blood deprived of its corpuscles), from 

 the albumen contained with it in solution. We at present know 

 nothing more of dissolved fibrin than the facts long ago advanced 

 by Joh. Miiller*. Neither acetic acid or caustic ammonia 

 induces a precipitate in the fluid of frogs 5 blood; but a concen- 

 trated solution of caustic potash will precipitate fibrin as well 

 as albumen (see p. 333); ether causes fibrin to coagulate, while 

 it allows the albumen of frogs' blood to remain dissolved. The 

 spontaneous coagulation of the fibrin from the plasma of all verte- 

 brate animals may be greatly retarded by dilute solutions of the 

 alkaline sulphates, nitrates, hydrochlorates, carbonates, and ace- 

 tates, and may even be entirely prevented by concentrated solutions. 



As we purpose treating somewhat fully of the spontaneous coagu- 

 lation of fibrin in the second volume of this work, when we enter 

 upon the consideration of the blood, we will now merely observe, that 



* Lehrb. d. Phys. Bd. 1, S. 117 [or vol. 1, p. 124 of the second Edition of 

 the English Translation.] 



