20 Dr. Buchanan on the Coagulation of the Blood. 



the effect of the colourless buffy coat to be much greater than that of 

 the red clot. I also found the upper part of the red clot to have a 

 stronger coagulating power than the lower part of it. These facts 

 seemed to show that it was the colourless corpuscles of the blood in 

 which the coagulant power was mainly seated. The colourless 

 corpuscles rise to the surfaco on the blood being drawn, and, there 

 exerting their coagulating power, render the upper part of the clot 

 invariably much firmer than the lower part of it; and this is exactly 

 what is seen in a more marked way, in inflamed blood, in which the 

 colourless corpuscles are much more abundant, and rising by their 

 levity to tlie surface, form a layer on the top of the red corpuscles; 

 and thereafter, by their superior coagulating power, give rise to the firm 

 crassamentum without redness which we name the buffy coat. As I 

 knew the transparent coagulum, which we find on the surface of newly 

 formed blisters, to consist chiefly of such colourless particles, I tried it 

 as a coagulant, and found it to induce coagulation, although less power- 

 fully than the washed clot of blood. The coagulum, formed artificially 

 in hydrocelic serum by different reagents, seemed to have little coagu- 

 lating power ; as if the transparent granules of fibrin must not only be 

 precipitated, but have acquired more or less of the organized vesicular 

 shape which they have in the blood and in the blister-liquid, before 

 they possess the power of coagulating. This power seemed, therefore, 

 to be the result of organization, and analogous to the metabolic power 

 which Schwann has ascribed to the elementary cellules. This view led 

 me to think it probable, that all the tissues of the body might have a 

 similar power of reacting upon the liquor sanguinis effused into their 

 meshes, and thus contributing to their own development, by engender- 

 ing there such vesicles as we meet with in the blister-liquid. My first 

 trials made with the muscle and skin of beef well washed to free them of 

 blood, did not succeed ; but on trying the muscle of veal, I found it to 

 produce coagulation. I afterwards recognized a similar coagulating 

 power in the muscular substance of beef and veal, in white-fish, skin, 

 and cellular membrane: but the effect produced was less remarkable 

 than that of the washed clot, and required a longer time, generally 

 from one to three days. The tissue which answered best was the 

 spinal marrow, probably in part from its greater softness and diffusi- 

 bility. On one occasion, I found the spinal marrow of a bullock to 

 cause coagulation in half-an-hour, the coagulum formed being very firm 

 and beautiful. The substance of the brain seemed to have less power, 

 although no rigorous comparison of them was made. Last of all, I 

 found that the corpuscles of mucus from the Schneiderian membrane 

 and throat possessed a coagulating power, though tardy: and that 

 even the globules of purulent matter, which are just altered primary 

 cellules, retained their coagulant power ; for when put into hydrocelic 

 serum, instead of continuing diffusible through the liquid, they 

 agglutinated themselves together by the intermedium of fibrin, forming 



