134 Dr. Buchanan on the Fibrin contained in the Animal Fluids, 



had formed a firm coagulum, occupying at first the whole extent of 

 the liquid, but gradually contracting in size. It may be affirmed, 

 then, in general, that if the vesicated skin has not been so much 

 injured as to interfere with its healthy actions, the blister-liquid 

 always yields a coagulum of fibrin, which becomes more and more 

 abundant, as the blister is the longer unbroken, up to the period when 

 coagulation takes place within the blister itself. This period occurs 

 sooner or later, according to the size of the blister, the vigor of the 

 constitution, and probably other circumstances not yet ascertained. 

 The coagulation is sometimes so complete after the application of a 

 blister during twelve hours, that the liquid drawn off yields little or 

 no fibrin; and sometimes, as iu the case just mentioned, the fibrin is 

 not coagulated when the blister is several days old. 



4. Contains microscopic globules, which form coagulum. — We have 

 thus the process of coagulation taking place in circumstances 

 peculiarly favourable for determining its nature,, for we can examine 

 the liquid before, during, and after coagulation, and thus witness all 

 the steps of the process. 



"When we examine the liquid under the microscope immediately 

 after being withdrawn from the blister, or shortly thereafter, we find 

 it to contain transparent vesicles floating free in the liquid. These 

 vesicles are pretty uniform in size, are nucleolated, and resemble very 

 closely the corpuscles of the blood. (Fig. 1.) Their number varies 

 in different cases. When they are very numerous they speedily attract 

 each other, and run together into a mass of fibrin. This mass is at 

 first distinctly seen to be made up of a congeries of the vesicular 

 corpuscles, (Fig. 2.) but it continues, probably under the influence of 



Fig. 1. Fig. 2. 



EXPLANATION OF WOOD-CUTS. 



Fig. 1st, Appearance of Blister Liquid soon after being drawn off. Vesicles mostly 

 isolated : a few of them coalescent, forming small masses of fibrin. 



Fig. 2dj A coagulum of Fibrin, in which the vesicular structure is still distinctly 

 'visible. 



