FIBRIN. 349 



the liquor sanguinis (after the removal of the blood-corpuscles) will 

 frequently assume a thick fluid and gelatinous character within two 

 minutes after its removal from the living body; in a short time some 

 drops of fluid appear on the tolerably consistent jelly, and speedily 

 augment, until they form an entire stratum of serum over the now 

 fully developed coagulum ; this coagulum now begins to contract, 

 becoming more or less tenacious, tough, elastic, and resistent, 

 according to certain accompanying conditions (as we shall more 

 fully explain when treating of the blood). If we trace this tran- 

 sition of the fibrin from the dissolved fluid condition into the 

 solid state under the microscope, a careful observation shows us 

 that the fresh liquor sanguinis exhibits nothing morphological 

 beyond some few colourless blood-corpuscles ; when it begins to 

 gelatinise, separate points or molecular granules appear at various 

 spots, from which arise extremely fine straight threads in radiating 

 lines, although they do not form star-like masses as in crystallisa- 

 tion; these threads becoming elongated cross those springing from 

 other solid points until the whole field of view appears as if it were 

 covered with a delicate, but somewhat irregular cobweb. This 

 net- work finally becomes so dense that the colourless blood-cor- 

 puscles imbedded in it can scarcely be distinguished. 



It is scarcely necessary, at the present day, to offer any refuta- 

 tion of the older views, according to which, on the one hand, 

 fibrin arose from the bursting of the colourless or even of the red 

 blood-corpuscles, while, on the other, it was simply deposited from 

 the blood in which it was originally only suspended. The former 

 view has long ceased to be held by physiologists, while microscopic 

 observations affords ample evidence of the untenability of the latter 

 hypothesis. 



As yet no satisfactory solution has been afforded to the question 

 which has been frequently raised regarding the means by which the 

 fibrin is held in solution in the circulating blood, and by which it 

 is disposed to coagulate on the removal of the plasma from the living 

 body. Various facts prove, indeed, that the access of the air (that is 

 to say, of the oxygen,) greatly influences the coagulation of the fibrin ; 

 but it is doubtful whether this is the only cause of coagulation, 

 since the same process goes on within the vessels of the living 

 organism, as soon as the blood ceases to circulate. This question 

 cannot be answered chemically, since we are at present acquainted 

 only with the product of this process, while it is requisite for a 

 correct judgment of it that we should know not only the end, but 



