420 



BLOOD, MORBID CONDITIONS OF THE. 



specific gravities were 1-044, 1-038, 1-052, 

 1-056; and in one instance in which it was 

 thick, the specific gravity was 1'057. Taking 

 the mean gravity of healthy blood at 1-044, 

 which I believe will be found correct, it would 

 thus appear that the buffy coat is more frequent 

 in blood above than below the mean weight ; 

 but it is also clear that it may exist in either 

 state, and the number of experiments is not 

 sufficient to lead to any conclusive result. 



De Haen, Hewson, and others have met with 

 cavities in the crassamentum of buffed blood 

 containing clear fluid (liquor sanguinis), which, 

 on being evacuated several hours afterwards, 

 separated into fibrine and serum. This fact is 

 analogous to that of fluid blood having been 

 found by Hewson in the heart of a dog thirteen 

 hours after death, which blood, on being re- 

 moved, coagulated soon after exposure to the 

 air. A similar coagulation will occasionally 

 take place in fluid blood taken from the human 

 heart several hours after the extinction of life. 



The remote cause on which the occurrence 

 of the buffy coat depends appears to be an 

 increased action in the circulating system, de- 

 pendent on increased nervous energy, and this 

 is capable of being very speedily excited. Thus 

 it has happened* that blood from the same 

 orifice drawn into four cups has exhibited this 

 appearance in the second or the third cup, 

 and not in the first or last, the difference being 

 plainly owing to a faintness felt at the com- 

 mencement and termination of the venesection. 

 Thus also the blood of healthy horses drawn 

 immediately after a smart gallop while the cir- 

 culation is powerful and rapid, will exhibit a 

 buffy coat, while that previously abstracted 

 will of course shew no such appearance. 

 Scudamore, it is true, arrived at an opposite 

 result in the case of a young man whom he 

 bled, and after causing him to run two miles, 

 bled again. Neither before nor after the race 

 was the blood buffed, but it is obvious that such 

 severe exercise after depletion would exhaust 

 rather than augment the powers of the nervous 

 and circulating systems. Accordingly he found 

 the proportion of fibrine diminished in the blood 

 last drawn, while the specific gravity of the 

 serum was increased from 1-030 to 1'035, thus 

 shewing how large a quantity of moisture must 

 have been carried off by perspiration. 



The buffy coat, as might be anticipated from 

 its cause, is usually found in connexion with 

 those diseases and even conditions of health 

 in which vascular action is preternaturally 

 increased in the active stages of peripneu- 

 mony, in pleurisy, in inflammatory fever, scar- 

 latina and the eruptive diseases generally, and 

 very uniformly in acute rheumatism. It is 

 also occasionally but not always met with in 

 the biood of pregnant women, in persons of 

 sanguine temperament and full habit, and those 

 who resort to frequent bloodletting ; in chronic 

 rheumatism, gout, enlargement of the heart, 

 and other affections where no inflammation 

 exists. On the other hand, it may be absent 

 even in the most intense inflammation; for the 



* See Hewson on the blood, vol. i. p. 82 et seq. 



circulation may be so overcharged either 

 actually or relatively, or the nervous power so 

 oppressed, that the requisite degree of propul- 

 sive force is not exerted by the heart and 

 arteries, nor the vital energy on which slow 

 coagulation depends imparted to the blood. 

 In such instances the buffed coat generally 

 appears on a second or third repetition of 

 venesection. 



Louis found the blood covered by a firm 

 thick buff at each bleeding in nineteen cases 

 of fatal peripneurnony out of twenty-four. In 

 two-fifths it was cupped. In fifty-one out of 

 fifty-seven cases of recovery the blood was 

 buffed, and in twenty- three cupped. In nine 

 tenths of rheumatic patients the buff was firm 

 and thick. 



The form of the receiving vessel, the degree 

 of motion to which it is subjected, and the 

 size of the orifice in the vein, materially in- 

 fluence the phenomenon. M. Belhomme, the 

 experimenter under M. Recamier, has made 

 aboutone hundred and fifty experiments on blood 

 drawn in health and disease. Ke has come to 

 the conclusion that a medium orifice one line in 

 the vein, a strong, rapid, and continuous jet in 

 the form of an arch, and a narrow vessel for 

 the reception of the blood, are the external 

 circumstances most favourable for producing 

 the buffy coat.* 



Fibrine is more abundant in buffed than in 

 healthy blood. Dr. Davy, from his observa- 

 tions, infers that there is no constant relation 

 between the appearance of this covering and the 

 proportion of fibrine in the crassamentum, yet 

 his own tabular report contradicts him. " From 

 all the examinations we have made," says 

 Thackrah, who has made many experiments to 

 determine this point, " I infer without hesita- 

 tion that buffed blood contains a considerably 

 greater proportion of fibrine than healthy 

 blood." This is a fact of much interest and 

 importance, for as very slight aud sudden causes 

 may give rise to the formation of a buffed coat, 

 we are thence led to infer that the quantity of 

 insoluble matter which separates from liquor 

 sanguinis by coagulation is variable, and that 

 there is so far reason to believe that fibrine and 

 albumen are principles convertible into each 

 other. 



In connection with the appearances depen- 

 dent upon the slow coagulation of fibrine, I 

 may here notice the occurrence of what have 

 been termed polypi, or more recently and cor- 

 rectly, false polypi in the hea't and larger ves- 

 sels. These are so common, that, as Haller ob- 

 serves, scarcely a body is met with in which 

 they do not exist. They are found in both 

 auricles and both ventricles and in the larger 

 arteries and veins, as well of the trunk as of the 

 extremities. They consist essentially of fibrine, 

 and partake of all the varieties that are obser- 

 vable in the fibrinous coat of buffed blood. 

 Haller affirms, as usual, supporting his opinion 

 by numerous authorities, that these have been 

 known to exist even during life, not only in 



* See also Med.-Chir. Trans, vol. xvi. p. 296, 

 note. 



