Dr. Anderson <m the state in which Fibrin exists in the Blood. 201 



Dr. A. Buchanan.* These gentlemen hold, that while of the cor- 

 puscles of the blood the red take no part in the coagulation, and 

 are merely engaged as it were by accident in the clot, from which, by 

 the above mentioned means, they may be artificially excluded ; yet 

 the white corpuscles and the molecules which exist in the fluid, really 

 constitute the fibrin : and that the coagulation consists simply in the 

 aggregation of these previously isolated bodies. Dr. Buchanan's 

 opinion to this eflfect is based, not upon the direct examination of the 

 process of coagulation in the blood, but upon what he conceives to occur 

 in the case of the fluid of blisters and of serous cavities, and to furnish 

 an analogical argument of considerable weight. 



Now, it is true that the fluid of blisters contains corpuscles like the 

 white globules of the blood, and also that it coagulates on standing ; 

 and it may be likewise true, that the number of the corpuscles is in 

 the ratio of the size of the clot : but I have carefully watched the fluid 

 of a recent blister coagulating under the microscope, and find that 

 the delicate clot forms independently of the corpuscles, as it is seen to 

 occupy the whole area of the field of view, while at most two or three 

 corpuscles may be scattered over it. 



Again, it is true that in the very curious experiment which we owe 

 to Dr. Buchanan, the mixture of the serum of blood and of that of 

 hydrocele, exhibits after standing for some time a marked coagulum ; 

 but I submit that neither is this a proof that that coagulum is derived 

 from the corpuscles existing in the fluid in which it forms ; for I have 

 divided such a mixture into two equal parts, and while leaving one 

 untouched have separated by filtration all the corpuscles from the other, 

 while still fluid, and tested their absence by the microscope, and yet the 

 eye could detect no difference between the coagula subsequently formed 

 in the two portions — nor, when aided by the microscope, any corpuscles 

 newly formed. 



But the experitnentum crucis is the examination of the changes 

 which occur in the plasma of the blood itself ; and this may be effected 

 by removing with a spoon a portion of the incipient buffy coat, (the 

 whitish fluid which floats before coagulation on the surface of inflam- 

 matory blood,) and placing it under the microscope. This fluid is the 

 blood minus the red corpuscles, which, as Mr. Wharton Jones has 

 shown,t attract one another more strongly in inflammatory than 

 in healthy blood, and sink rapidly in the fluid. Our view, then, 

 of the changes which occur being no longer obscured by their pre- 

 sence, we watch the plasma swarming with molecules and white cor- 

 puscles, the latter always most abundant in inflammation, as may 

 be seen even by placing a drop of the just abstracted blood 

 under the microscope between two plates of glass, to which the 



* Proceedings of the Glasg. Philos. Soc. 1B43, p. 131. 

 t Ed. Med. and Surg. Journal, 1842. 



