FIBRIN A COLLOID BODY. 727 



of the fibrin, may have some relation to the distinction between the 

 crystalloid arid the colloid condition of matter. (Graham.) Fibrin, like 

 all albuminoid bodies, is a colloid substance; and one of the properties 

 of these, is a proneness to molecular, or molar metastases, by which 

 they pass, not only from a pectous to a liquid, but also from a liquid 

 to a pectous state (p. 607). Albumen undergoes this latter change, 

 on the application of heat; casein, on the addition of acid pepsin, or 

 of an acid with heat, and fibrin, still more readily than either, becom- 

 ing, when left to itself, solidified at moderate temperatures, arid more 

 rapidly, at somewhat higher temperatures. The coagulation of fibrin 

 not being due to any external apparent cause, has been designated 

 spontaneous. But this more ready assumption by fibrin, of the pectous 

 condition, can hardly be spontaneous, in the usual sense of that term ; 

 unless, indeed, we suppose the vital endowments of this remarkable 

 substance to be higher even than Hunter believed. Crystallization is 

 as much spontaneous in one sense as coagulation. The latter probably 

 depends upon some definite molecular or molar changes, strictly phys- 

 ical, like any other less rapid effect of colloidal energy, and occurring 

 when the fluid fibrin is removed from the ordinary influence of processes 

 going on in the living vessels and tissues within the body, or when it 

 is subjected to other influences exerted upon it by the dead tissues, or 

 by foreign bodies generally. 



The action of these latter may be catalytic, or due to contact, and 

 the fact that rough or multiplied surfaces accelerate coagulation, favors 

 this view. It has been suggested that dead matter may induce a reac- 

 tion between the solid and fluid constituents of the blood, in which the 

 former, that is the corpuscles, impart to the fibrin of the liquor san- 

 guinis a disposition to coagulate. When, however, no foreign substance 

 is introduced into the blood, the catalytic action has been supposed to 

 be due to the corpuscles themselves, which, as it were, ceasing to undergo 

 their characteristic vital changes, and so, in effect, becoming dead, 

 determine, like other dead animal matter, the solidification of the fibrin. 

 (Lister.) The influence of the red corpuscles in producing or acceler- 

 ating coagulation is well established; the upper colorless stratum of 

 either inflammatory or diluted blood, in which the corpuscles have sub- 

 sided, coagulates more slowly than the lower part, in which the corpuscles 

 are present. (Gulliver.) Chyle, to which a minute portion of blood is 

 added, will coagulate in two or three minutes, though the same, when 

 pure, takes from twenty-five to ninety minutes to coagulate. (Schmidt.) 

 The fluids of ascites, pleurisy, and pericarditis, that of blisters, and 

 of other so-called serous exudations, readily coagulate after the addition 

 of a minute quantity of blood, even, it is said, of a few red corpuscles ; 

 whilst other portions of those fluids, kept apart, do not. The same 

 effect is produced, however, on the admixture of two such fluid exuda- 

 tions. Fragments of the crystalline lens, the composition of which re- 

 sembles, or is identical with, the globulin of the red blood corpuscles, 

 and even the crystals of haemato-globulin obtained from those cor- 

 puscles, also induce the formation of a coagulum in these fluids. Hence 

 Schmidt, to whom these latter observations are chiefly due, believes 

 that, within the blood cells, there exists a fibrin o-plastic substance, and 



