SINKING TENDENCY OF THE CORPUSCLES. 165 



acid should render the blood-cells viscid, and tend to make them 

 assume the nummular arrangement, since we may very readily 

 observe in fresh blood the commencement and gradual formation 

 of these rolls of corpuscles under the miscroscope ; in the minute 

 drops which we use for microscopical observation any excess of car- 

 bonic acid would disappear in the process of manipulation, and in 

 every case more oxygen would be taken up than is contained in fresh 

 blood. Hence each of these three different modes of explaining 

 the tendency of the blood-corpuscles to sink is opposed by definite 

 facts which at present do not allow of any satisfactory explanation 

 of the phenomenon. Only this much appears to be distinctly 

 established, that, in addition to the influence exerted by the 

 relative density of the corpuscles and the serum, their viscidity 

 must essentially promote their aggregation. Moreover, we never 

 observe this cohesion or peculiar aggregation of the red cells in the 

 blood while still circulating. The tendency of the red corpuscles 

 to sink is usually very distinctly observed in the blood of per- 

 sons with inflammatory diseases, or in such blood as contains a 

 diminution of the salts and a relative increase of the albumen. 

 A great sinking tendency of the blood-cells is very often accom- 

 panied by a watery liquor sanguinis. When the blood-corpuscles 

 are dark-coloured (and may therefore be regarded as rich in 

 hsematin or iron), they have a tendency to sink very rapidly, and 

 to form nummular rolls ; when they are of a pale colour (and are 

 rich in fat), they only sink slowly. The blood-corpuscles of the 

 horse, which sink more rapidly than those of any other animal, are 

 comparatively poor in fat. Repeated venesections increase the 

 tendency of the blood-cells to sink ; they then become richer in 

 hsematin, as has been shown by C. Schmidt; they have thus 

 become relatively heavier, and therefore sink more readily ; the in- 

 crease of hsematin in the corpuscles is here certainly only relative ; 

 in consequence of the diluted plasma, an excess of globulin is 

 abstracted from the blood-cells, which thus become comparatively 

 richer in hsematin, and poorer in globulin. If we consider these 

 facts and we shall presently notice some additional ones we 

 certainly feel inclined to ascribe a greater influence than we 

 formerly did to the difference of the densities of the blood-cells 

 and the intercellular fluid, in relation to the sinking of the 

 corpuscles. 



In special cases several conditions are often simultaneously 

 present, which exert an accelerating or impeding influence on the 

 sinking of the blood-corpuscles ; thus, for instance, the coloured 

 cells of the blood of the hepatic veins of the horse sink very little, 



