BLOOD, MORBID CONDITIONS OF THE. 



tractflity, so as to contain a large portion of 

 fluid, or from its holding entangled among its 

 meshes an unusual number of red particles ; 

 but it will often also arise from there being a 

 more than ordinary quantity of fibrine present, 

 in which case it will be firm and contractile as 

 well as voluminous. Blood thus circumstanced 

 is said to be rich and thick, and is generally 

 met with in those whose complaints are con- 

 nected with a plethoric habit. 



A deficiency in the proportion of fibrine is 

 likewise not unfrequent among those who suffer 

 from complaints of debility, or who have lost 

 much blood by natural or artificial depletions. 

 In this case the clot is small, and has but little 

 contractile power. 



It is, I conceive, a possible case, that the 

 fibrine may separate imperfectly or not at all, 

 in consequence of an augmented proportion of 

 salts, which out of the body we know to be 

 capable of suspending coagulation altogether. 

 The continued use of alkaline remedies will 

 probably tend to produce a like effect. 



Fibrine coagulates the more speedily in 

 porportion as the circulating and nervous sys- 

 tems become more feeble. The experiment 

 has been repeatedly made with animals that 

 are killed by bleeding, and the last por- 

 tions of blood invariably coagulate soonest. 

 * The principle of the blood's speedy con- 

 cretion in debility is important in a curative 

 point of view. The first natural check to hae- 

 morrhage is known to be the formation of a clot 

 on the mouth of the vessel. If the longer the 

 haemorrhage the less had been the disposition to 

 form such a clot, the wounded on the field of 

 battle, and those injured by common accidents, 

 who cannot promptly procure the aid of a 

 surgeon, must inevitably have perished."* 



One of the most remarkable and frequent de- 

 viations from the normal condition of blood 

 removed from the body by venesection, is the 

 occurrence of the buffy coat, which is a layer of 

 fibrine occupying the surface of the crassa- 

 mentum. The blood, whilst circulating within 

 its vessels, consists, as I have already remarked, 

 of a fluid which I have elsewhere ventured to 

 call liquor sang u in is, and of insoluble red par- 

 ticles. These being in constant motion are 

 uniformly diffused throughout this liquor; but 

 their specific gravity being much greater than 

 that of the medium in which they are sus- 

 pended, they have a tendency to gravitate when- 

 ever that motion ceases. In healthy blood the 

 fibrine coagulates so quickly that the red par- 

 ticles have not time to subside, so as to leave 

 any portion of the liquor entirely free from 

 them. By protracted fluidity this result is 

 effected ; the red particles do then gravitate to a 

 greater or less depth before the liquor separates 

 into two parts. A general coagulation of the 

 fibrine at length occurs, and a clot is formed. 

 That part of it through which the red particles 

 had fallen becomes a layer of fibrine free from 

 colour, and merely having some serum mecha- 

 nically retained in its meshes, while the sub- 

 jacent portion is of intense depth of shade, 



* Thaqkrah, p. 188. 



419 



especially at the bottom, and of less than ordi- 

 nary cohesion. In extreme cases, such an 

 abundance of red particles reaches the bottom 

 of the vessel that they are there found in a 

 state of fluidity. The buffed layer sometimes 

 assumes a cupped form, which is clearly owing 

 to unequal contraction. The upper surface 

 being freer from intervening red particles, con- 

 tracts more powerfully than the under, and a 

 concavity of the surface is the necessary con- 

 sequence. Where, however, the contraction is 

 weaker, the weight of the subjacent red clot, 

 which is one and the same mass with the upper 

 colourless portion, weighs this down, and keeps 

 it in a horizontal position. 



The crassamentum of arterial as well as of 

 venous blood has frequently been observed to 

 exhibit a buffy coat. It is rarely seen in blood 

 extracted by cupping-glasses, and never in that 

 pressed from leeches. It occurs in the lower 

 animals, and is observed as frequently in the 

 horse as in the human subject ; indeed, from 

 the quantity of blood usually drawn from that 

 animal, it is still more strikingly apparent, being 

 occasionally several inches thick. It has been 

 denied that the cupped appearance is ever met 

 with in the blood of the horse ; but if this be 

 received into a sufficiently small vessel, it will 

 be in some instances as complete as in blood 

 taken from the human subject. There are va- 

 rieties in the appearance of the buffed coat 

 which it is worth while to notice. It is gene- 

 rally of a firm uniform consistence, and of a 

 light yellow or buff colour, whence its name. 

 Sometimes, however, it is of a more spongy 

 texture, and of a white or bluish, and more 

 transparent hue. Two layers of buff are occa- 

 sionally seen ; the upper soft or friable, the in- 

 ferior more compact. " There is a difference," 

 says Sir Gilbert Blane, " in the appearance of 

 the blood when sizy, perhaps not sufficiently 

 insisted on by practical writers; for though 

 there should even be a very thick buff, yet if 

 the surface is flat, and the crassamentum tender, 

 no great inflammation is indicated in com- 

 parison of that state of the blood wherein the 

 surface is cupped, the crassamentum contracted 

 so as to form the appearance of a large pro- 

 portion of serum, and where it feels firm and 

 tenacious, though perhaps but thinly covered 

 with buff."* 



From the examination of several specimens! 

 of buffed blood, I was at one time led to be- 

 lieve that its serum was always deficient in 

 its due proportion of albumen ; but this I have 

 Since found not to be the case, having met 

 with blood thickly buffed, the serum of which 

 at 60 Fahr. had a specific gravity of only 

 1*024, and with another specimen where the 

 layer of fibrine was equally thick, of which, 

 at the same temperature, the serum had a spe- 

 cific gravity of 1-040. Dr. John Davy examined 

 the specific gravity of buffed blood in eleven 

 cases. In five of them in which the buffy 

 coat was slight, the specific gravities were T047, 

 1-051, 1-054, 1-055, 1-054; in five others in 

 which the buffy coat was moderately thick, the 



* Blane on the Diseases of Seamen, note to page 



2 E 2 



