240 OF THE BLOOD: 



is very pale when they are lying in a single stratum ; and it is only when 

 we see three or four or more together in rolls or clumps, that the full, deep 

 red tint of their contents becomes apparent. The cause of the difference in 

 hue between the corpuscles of arterial and those of venous blood, will be 

 considered hereafter. 



175. The Red Corpuscles, when freely floating in the liquor sanguinis 

 of blood no longer in motion, exhibit a marked tendency to approximate 

 one another ; usually coming into contact by their flattened surfaces, so 

 that a number of them thus aggregated present the appearance of a pile 

 of coins ; or, if the stratum be too thin to permit them to lie in this manner, 

 partially overlapping one another, or even adhering by their edges, which 

 then frequently become polygonal instead of circular. The corpuscles, when 

 thus adherent, resist the influence of forces which tend to detach them, and 

 will even undergo considerable changes of shape, rather than separate from 

 each other; if forced asunder, however, they resume their normal form. 

 After thus remaining adherent for a time, they seem to lose their attractive 

 force ; for they are then seen to separate from each other spontaneously. 

 This peculiar tendency to aggregation is most strongly manifested in inflam- 

 matory blood, and assists in the production of the bufly coat ; whilst, on the 

 other hand, it seems to be neutralized by the action of most saline sub- 



FIG. 105. FIG. 106. 



FIG. 105. Red corpuscles and pale cells of blood and lymph-globules. At a, four red corpuscles; 

 6, five pale globules ; c, d, four lymph-globules. The first pale globule, at 6, contains spherical granules, 

 the last is only minutely granular, and the fourth is collapsed and sending off processes: these three 

 globules are in the natural state, but the second shows its circular nucleus exposed by the action of 

 weak acetic acid, and the third the nucleus divided after treatment by stronger acid. Of the lyinph- 

 glol.ules (which are from an inguinal gland) at c, the first two are in their natural state ; and at d, the 

 last two, after having been long steeped in strong acetic acid. From a child, aged three, accidentally 

 killed. 



FIG. 106. Red corpuscles of Man (on the same scale of one-four-thousandth of an inch, as marked at 

 Fig. 103). At a, the corpuscles are seen flat, on edge, and in rolls; the two first corpuscles show the 

 central spot or concavity, dark and light; next are shown the biconcave and concavo-convex forms; 

 among the rolls, one corpuscle is drawn out by virtue of its viscidity, and would resume its circular 

 shape by virtue of its elasticity. 



stances, since if these be added to the blood the corpuscles do not run 

 together, or instantly separate if they have already become adherent. It 

 appears to be a purely physical phenomenon, dependent on the relations of 

 cohesion existing between the particles of solids and fluids. 1 



1 See Dr. Norris, of Birmingham, Proceed, of Roy. Soc., No. 112, 1869, who has 

 shown that it can be closely imitated by pariially immersing poised cork disks in 

 water or other liquid, the particles of the solid outside the liquid having an attrac- 

 tion for each other, which, owing to the slight resistance offered by the fluid, leads 

 to movement through very sensible distances. Such disks exhibit no tendcacy to 



