IS COAGULATION A VITAL ACT? 723 



fibrillse. Again, by adding a solution of salt, or of sugar, to a quantity 

 of frog's blood, the corpuscles of which are very large, the fluid part 

 of the blood, or liquor sanguinis, maybe actually filtered from the cor- 

 puscles, and will afterwards undergo coagulation. 



The cause of the solidification of the fibrin has been the subject of 

 much speculation and difference of opinion, and is still not satisfac- 

 torily understood. 



Many living physiologists, agreeing with Harvey, Hunter, and 

 others, maintain, as already stated, that the coagulation of the blood 

 is a manifestation of vital power in that fluid. Harvey said of the 

 blood, that it was the primum vivens and the ultimum moriens of the 

 body ; whilst Hunter considered the coagulation of the blood as its 

 last act of life. An analogy has been drawn, somewhat vaguely, 

 between the solidification of the fibrin of the blood and muscular con- 

 traction, and, perhaps, with more justice, between it and the rigor 

 mortis, or rigidity of the muscular tissue after death. Several modern 

 authorities perceive in the fibrillation of the solidifying fibrin, the evi- 

 dence of an organizing plastic process, the feeble efforts of a forma- 

 tive vital energy. Moreover, it is urged that effusions, undoubtedly 

 fibrinous, upon the surfaces of serous membranes, in the interior of 

 the eyeball, between the ends of tendons or other cut surfaces divided 

 subcutaneously, and in other situations, become organized and vascu- 

 lar, and are converted into a low form of areolar or fibrous tissue ; and 

 that not merely fibrin, but even blood clots in the interior of vessels, as 

 in cases of ligature of arteries, or blood extravasated in the midst of 

 the tissues, may also become, under certain circumstances, vascular- 

 ized, and converted into a definite tissue, in the same way as inflam- 

 matory fibrinous exudations are, the blood corpuscles not assisting in 

 the process, but rather delaying it. (Hunter, Zwicky, Paget, Hewett.) 



Notwithstanding the support given to the idea of the coagulation of 

 the blood being a vital act, and of the possession of a vital property of 

 solidification by the fibrin of that fluid, it may be doubted whether this 

 doctrine is correct. There is no real analogy between muscular con- 

 tractility, which requires peculiarities of structure, and complex stati- 

 cal and dynamical electric conditions, and the simple change of the 

 fibrin of the blood from a fluid to a solid state. If its comparison 

 with the rigor mortis be more exact, the tendency of modern opinion 

 is to regard this phenomenon not as a vital act, but truly as a rigidity 

 of death, dependent on chemical changes then ensuing. Again, there 

 is no true resemblance between the minute fibrillse of solidified fibrin 

 and any fibrous or other tissue of the body ; the former are homoge- 

 neous, the latter, indeed, always present differences of parts. Fibrin- 

 ous deposits or effusions may become the seat of positive organization, 

 so as ultimately to give rise to a tissue; but then nuclei, or centres of 

 growth, arranged in methodical order, and even cells, appear within it, 

 for the formation of the future tissue elements and the new capillary 

 vessels ; these nuclei and cells are supposed to have their origin, not in 

 the fibrin, but from the corresponding parts of the surrounding tissues. 

 In cases of so-called organization of the coagula formed in ligatured 

 arteries, in the interior of inflamed veins, or in other situations amidst 



