PROPERTIES OF THE BLOOD. 441 



separates itself from the fluid in which it was previously dissolved ; and during 

 its coagulation it attracts the red particles ; these are included in areoke or 

 meshes of the Clot, the substance of which has a tendency to assume a fibrous 

 arrangement ( 554) ; and they usually group themselves together in columnar 

 masses, resembling piles of money (Fig. 100, B). The Coagulum or clot be- 

 comes dense in proportion to the amount of Fibrin it contains ; and the Albu- 

 minous and Saline matter still dissolved in the water are separated from it, 

 constituting what is called the Serum. This separation will not occur, how- 

 ever, if the coagulation takes place in a shallow vessel ; nor if the amount of 

 Fibrin should be small, or its vitality low. A homogeneous mass, deficient in 

 firmness, presents itself under such circumstances ; though the solid part of 

 this may pass into a state of more complete condensation, after the lapse of a 

 certain time. That the coagulation is due to the Fibrin, and that the Red 

 particles are merely passive in the process, appears from several considera- 

 tions. A microscopical examination of the Clot shows that it has the same 

 texture with Fibrin when coagulating by itself; the Corpuscles clustering 

 together in the interspaces of the network, and not being uniformly diffused 

 through the whole mass. Their Specific Gravity being greater than that of 

 the Fibrin, they are usually most abundant at the lower part of the clot ; and 

 the upper surface is sometimes nearly colourless, especially when the coagu- 

 lation has taken place slowly ; yet this upper part is much firmer than the 

 under, showing that the Fibrin alone is the consolidating agent. This has 

 been proved to demonstration by an experiment of. Muller's. He placed the 

 blood of a Frog, diluted with water (or still better with a very thin syrup) on 

 a paper filter, of sufficiently fine texture to keep back the Corpuscles ; and 

 the Liquor Sanguinis, having passed through the filter completely unmixed 

 with them, presented a distinct coagulum, although from the diluted state of 

 the fluid, this did not possess much consistency. Owing to the more minute 

 size of the Blood-discs of warm-blooded animals, this experiment cannot be 

 performed with their blood ; but there is no reason to believe its constitution 

 to be different. In fact, the sole agency of the Fibrin in coagulation is very 

 easily proved in another way. If fresh-drawn blood be continually stirred 

 with a stick, the Fibrin will adhere to it in strings during its coagulation ; 

 and the red particles will be left suspended in the serum, without the slightest 

 tendency to coagulate. Moreover, if a solution of any salt, that has the pro- 

 perty of retarding the coagulation (such as carbonate of potash or sulphate of 

 soda), be added to the blood, the Corpuscles will have time to sink to the 

 lower stratum of the fluid, before the clot is formed ; the greater part of the 

 Coagulum is then entirely colourless, and is found by the microscope to con- 

 tain few or no red particles.* 



583. That the coagulation of the Fibrin is not, as some have supposed, a 

 proof of the death of the blood, but is rather an act of vitality, appears evident 

 from what has been already stated ( 554) of the incipient organization which 

 may be detected even in an ordinary clot ; and still more from the fact that, if 

 the effusion of Fibrin takes place upon a living surface, its coagulation is the 



*[M. Figuierj- has suggested an easy method for the rough analysis of the blood. By 

 adding to one volume of defibrinated blood, two volumes of a solution of sulphate of 

 soda, of sp. gr. making 16 to 18 in Baume's areometer, the corpuscles will separate 

 (as Berzelius showed), and may, with hardly an exception, be all collected on a filter. 

 Thus their quantity may be estimated, as that of the fibrine may very roughly by what 

 is obtained by whipping. The quantity of albumen may be estimated by boiling the 

 serum ; and the water, by evaporating a separate portion of blood. M. C.] 



f Report of the Academie des Sciences du 8, Juillet 1844; and, in full, in the Ann. de 

 Chimie et de Physique, Aout, 1844. 



