234 MANUAL Otf PHYSIOLOGY. 



adhering by their flat surfaces, so as to form into rolls, like so 

 many coins placed side by side. That this adhesion is not a mere 

 physical process, independent of the chemical properties of the 

 corpuscles themselves, seems proved by the following facts: (1) 

 It does not occur immediately when the blood is drawn, and it 

 disappears after a certain time without the addition of reagents ; 

 (2) while the blood is in the living vessels under normal condi- 

 tions there is no adhesion, but it soon appears when any stand- 

 still in the circulation takes place as in inflammation ; (3) it 

 does not occur when saline solutions are added to the blood. It 

 seems then to be dependent upon a peculiar property of the disks, 

 which only exists for a time coincident with the changes that 

 accompany the appearance of fibrin. 



FIG. 100. FIG. 101. 



FIG. 100. Microscopic appearance of the blood after the addition of distilled water. 

 Red Corpuscles become colorless or pale, separate and spherical. The white are seen to 

 be swollen, round and granular, with clear nuclei. 



FIG. 101. Showing effect of evaporation. Six Red Corpuscles crenated. (w) White 

 cell changing shape. 



The shape of the disks changes when the density of the medium 

 in which they are suspended is altered. When the density is 

 reduced, as by the addition of water, they swell and become 

 spherical, and break up the rouleaux, the coloring matter at the 

 same time becoming dissolved in the medium. (Fig. 100.) When 

 the density is increased by slight evaporation, or the addition of 

 salt solution about 1 per cent., they cease to be concave, and be- 

 come crenated or spiked like the green fruit of the horse chestnut. 

 (Fig. 101.) The addition of strong syrup causes the corpuscles 

 to shrivel and assume a great variety of peculiar bent or con- 

 torted forms. (Fig. 102.) Elevation of temperature or repeated 

 electric shocks causes peculiar changes in shape, but since the 



