BED BLOOD-COKPUSCLES. 73 



are made obscure ; but many of these latter may be brought 

 into view again by evaporating, or adding saline matter to, 

 the fluid, so as to restore it to its previous density. The 

 changes thus produced by water are more quickly effected 

 by weak acetic acid, which immediately makes the cor- 

 puscles pellucid, but dissolves few or none of them, for 

 the addition of an alkali, so as to neutralise the acid, will 

 restore their form though not their colour. 



A peculiar property of the red corpuscles, which is exag- 

 gerated in inflammatory blood, and which appears to exist 

 in a marked degree in the blood of horses, may be here 

 noticed. It gives them a great tendency to adhere together 

 in rolls or columns, like piles of coins, and then, very 

 quickly, these rolls fasten together by their ends, and 

 cluster ; so that, when the blood is spread out thinly on a 

 glass, they form a kind of irregular network, with crowds 

 of corpuscles at the several points corresponding with the 

 knots of the net (fig. 25'). Hence, 

 the clot formed in such a thin Fl 'ff- 2 5- :i 



layer of blood looks mottled 

 with blotches of pink upon a 

 white ground : in a larger quan- 

 tity of such blood, as soon as 

 the corpuscles have clustered 

 and collected in rolls (that is, 

 generally in two or three minutes 

 after the blood is drawn), they 



begin to sink very quickly ; for in the aggregate they pre- 

 sent less surface to the resistance of the liquor sanguinis 

 than they would if sinking separately. Thus, quickly sink- 

 ing, they leave above them a layer of liquor sanguinis, 

 and this coagulating, forms a buffy coat, as before de- 

 scribed, the volume of which is augmented by the white 

 corpuscles, which have no tendency to adhere to the red 

 ones, and by their lightness float up clear of them. 



* Fig. 25. Red corpuscles collected into rolls (after Henle). 



