COAGULATION OF BLOOD BUFFY COAT. 



303 



rated fibrine subsequently to its coagulation, it draws in the edges of 

 the upper surface of the clot, giving it a cupped appearance. 



536. The Buffy Coat may present itself under a great variety of 

 conditions ; and it can no longer, therefore, be regarded, as it formerly 

 was, a sign of the Inflammatory state. It is most fully developed 

 when acute Inflammation exists ; because in that condition all the 

 circumstances which favour it are present. That it may be produced 

 by any cause, which occasions delay in the coagulation of the blood, 

 is evident from the fact, that healthy blood may be made to exhibit it, 

 by adding a solution of a neutral salt, which retards, but does not 

 prevent its coagulation. But the blood may coagulate with its ordinary 

 rapidity, or even more speedily than usual ; and may yet exhibit the 

 Buffy Coat. And, moreover, the separation of the Fibrine and the 

 Red Corpuscles may take place in films of blood so thin, as not to 

 admit of a stratum of one being laid over the other ; the two elements 

 separating from each other laterally, and the films acquiring a speckled 

 or mottled appearance, equally characteristic of the Inflammatory con- 

 dition with the Buffy Coat itself. Hence the separation must be due 

 in such cases, to other causes than gravity : and recent observations 

 have accounted for it, by showing that the Red Corpuscles have an 

 unusual attraction for one another in the inflammatory state, causing 

 their coalescence in piles and masses ; whilst the particles of Fibrine 

 have also a peculiarly strong attraction for each other. Thus there is 

 a powerful tendency, that draws together the components of each kind, 

 and consequently tends to separate them from the others ; and when 

 this separation takes place, the difference in the specific gravity of the 



Fig. 87. 



The microscopic appearance of a drop of blood in the inflammatory condition. The red corpuscles lose 

 their circular form, and adhere together; the white corpuscles remain apart, and are more abundant 

 usual. 



two elements decides their respective situations. The peculiar ten- 

 dency of the Red corpuscles to unite, in the Inflammatory state, serves 

 to distinguish this condition even in a single drop of blood ; and 

 then that the White corpuscles may be most easily distinguished, a 

 they are seen apart from the rest of the mass, having no tendency t 



