SINKING TENDENCY OF THE CORPUSCLES. 163 



and of the defibrinated blood are known. If we assume, for instance, 

 that a specimen of blood contains 496 p.m. of moist blood-cells,, 

 besides 4 p.m. of fibrin, that the specific gravity of the serum is 

 1-0280, and that of the defibrinated blood 1-0574, then we may 

 very readily determine the density of the blood-cells by the 

 following considerations : 



996 parts of defibrinated blood occupy the space of 941-93 parts of water. 

 500 parts of serum 486 '38 



hence 496 parts of blood-cells 455-55 parts of water 



and, consequently, the density of the blood-cells in this specimen 

 of blood must be 1-0888. 



We now revert to the sinking tendency of the blood-corpuscles, 

 and its causes. If we microscopically examine a specimen of blood 

 in which the corpuscles sink with extreme rapidity, we find, as a 

 general rule, that the blood-discs lie with their sides in contact 

 with those of the adjacent discs, and thus form masses resembling 

 rolls of money (the nummular arrangement) ; while in blood in 

 which the serum and clot only separate slowly, the corpuscles for 

 the most part appear isolated. If from this it would appear, that 

 the nummular aggregation or cohesion of the blood-corpuscles is 

 the proximate cause of the more rapid sinking, the more remote 

 cause must be sought in a greater viscidity of the parts in question. 

 Henle believed that this property was especially dependent on the 

 tenacity of the intercellular fluid, and on the viscidity of the cells 

 that was thus induced : in accordance with a similar view, many 

 had previously regarded a superabundance of fibrin in the blood 

 as the cause of the cohesion of the corpuscles ; but independently 

 of the circumstance that numerous observations (made with the 

 view of deciding the question) prove that there is no connexion 

 whatever between the rapidity with which the corpuscles sink and 

 the proportion of fibrin in the blood, the perfect inertness of the 

 fibrin in relation to this phenomenon is indicated by the fact that 

 the corpuscles sink just as rapidly or just as slowly in defibrinated 

 blood as in blood which contains its fibrin. 



Hence the fibrin, at all events, exerts no influence on this 

 phenomenon. There then seemed to be a tendency to ascribe the 

 cohesion of the corpuscles to a great excess of albumen. In 

 favour of this hypothesis the following facts were adduced, 

 namely, that the addition of albumen or of other viscid solutions, 

 as, for instance, of sugar and gum, hastens the sinking of the 



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