374- Dr. Spurgin's Outlines of a Philosophical 



which occasionally happen. The same occiu's when death is 

 occasioned by the poison of the viper ; or by injury to the brain ; 

 or by some vegetable poisons, as laurel-water ; or by violent 

 passions of the mind, or by over-exertion of the body. In some 

 diseases, on the contrary, "its tendency to coagulation is greatly 

 increased. The striking difference that is observable between 

 blood drawn from a j)erson in full health and from one who is 

 labouring under inflammation, has excited the interest and in- 

 quiries of many medical men and chemists ; which difference 

 consists in the'surface of the coagulum being of a yellowish, 

 buffy, or leather-like appearance, instead of a dark or florid 

 red.*^ Numerous hypotheses have been broached to account for 

 this appearance. The immediate cause of this a):)pearance 

 in the crassamentum, says Dr. Bostock, is obvious: the glo- 

 bules, or other matter which give it the red colour, begin to 

 subside before the coagulation is completed, so that the upper 

 part of the clot is left without them ; the remote cause not be- 

 ing yet ascertained. 



I3r. Dowler made some experiments on the composition of 

 the buffy coat : and from these it appears that it contains a 

 very large proportion of serum, which by diminishing the vis- 

 cidity of the crassamentum, must more readily allow of the 

 subsidence of the red or colouring particles. The appearance 

 of a buff]y' coat on the surface of the blood is usually regarded 

 as indicative of the inflammation of some organ ; but as it 

 occurs in other states of the body, other discriminating signs 

 are sought after by the physician, to be convinced of its ex- 

 istence. The blood taken from a pregnant female most com- 

 monly exhibits this buffy coat; or collecting the blood in dif- 

 ferent vessels during the same bleeding will be followed by 

 the extraordinary circumstance, — that the first portion will 

 exhibit no such appearance ; the second will exhibit it in a 

 considerable degree; the third more or less so, and so on; 

 which changes Mr. Hewson is inclined to attribute to certain 

 alterations in the state and action of the blood-vessels ; whilst 

 more recent observations discover that the same results are 

 brought about by the more or less free escape of the blood 

 from the body, by the size of the orifice made in the vein, or 

 by the form of the vessel the blood is received into. In short, 

 these results all prove that the coagulation of the fibrin is liable 

 to alteration from various causes, or from the operation of vari- 

 ous influences. The difference in specific gravity between the 

 fibrin and serum varies according to numberless circumstances ; 

 for though in general the former subsides to the bottom of the 

 vessel containing tliem, yet it must be confessed it is sometimes 

 seen to be floating in the serum, and nearly on a level with its 



surface ; 



