40 PROPERTIES OF 



and its disposition to coagulation is lessened? both of which 

 circumstances contribute to the subsiding of the red globules 

 from the surface of the blood, which then coagulating gives 

 rise to this appearance, called the inflammatory crust or size, 

 in the blood of pleuritic or rheumatic patients. 1 



How contrary to the conclusion, which these* experiments 

 lead us to, are the opinions of some medical writers on this 

 subject ! How frequently do we find it said, that the blood is 

 thicker in inflammatory disorders, where that size occurs ; and 

 that a large orifice is necessary to let out the vitiated blood ! 

 That 'a large orifice is preferable to a small one in many cases, 

 where such blood is found, I believe to be true ; but that its 

 advantages are owing to its letting out the thickened blood, 

 seems improbable from what we have seen in the experiments 

 above related : they are perhaps nearer the truth, who attribute 

 it to the suddenness of the evacuation. 



It may be proper to observe here, that this size or whitish 

 crust is not a certain sign of inflammation (xxin) ; it being 

 1 This remarkable appearance might indeed be accounted for, by supposing that 

 the lymph had ascended to the surface of the blood in those cases ; but this is im- 

 probable, from considering that, in its coagulated state, it is of greater specific gravity 

 than the serum, and sinks in it. 



(xxiii.) That inflammation is not certainly indicated by the buffy 

 coat is shown by the fact that this part forms regularly on the blood of 

 the horse, as was probably known to Harvey. a It seems to have been 

 scarcely known to Dr. Simon, b though noticed by Dr. Allan Thomson, 

 and more particularly by Andral, d Gavarret, and Delafond; the last three 

 writers ascribe it, and the formation of the buffy coat generally, to an 

 excess of fibrin in relation to the other parts of the blood, as likewise did 

 some of the older observers referred to in Note I. The buffy state of the 

 blood from women far advanced in pregnancy is well known ; and Mr. 

 Hey e observed the great abundance of fibrin in such blood. 



Mr. Hewson inferred that the buffy coat is owing to an attenuation 

 of the liquor sanguinis, because he found in his ingenious and I believe 

 original experiments, that the red corpuscles sink more quickly in it 

 than in the serum alone. The fact is undoubted ; but the inference is 

 probably incorrect. The rapid sinking of the corpuscles during the 

 formation of the buffy coat arises simply from their clustering in such 

 blood, and not from any thinning of the liquor sanguinis nor from retarded 

 coagulation (see Notes xxi and xxix). The collection of the corpuscles 

 into piles in blood not buffy is well known (see Notes c and cix) ; in 



a De Generatione Animalium, 4to, Lond. c Syllabus of Lectures on Physiology, 

 1651, p. 160. p. 13, 8vo, Edin. 1835. 



b Animal Chemistry, i, pp. 115,292,340, d Hematol. Pathol. pp. 28 et seq. 8vo, 

 tr. by Dr. Day, for the Sydenham Paris, 1843. 



Society, 8vo, Lond. 1845. e On the Blood, p. 66, 8vo, Lond. 1779. 



