228 MANUAL OF PHYSIOLOGY. 



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 

 change is associated with the death of the element, it cannot be 

 attributed to vital activity comparable with that which is seen in 

 the white cells. 



The disks ehow no signs of structure under the microscope ; 

 they look perfectly homogeneous transparent bodies of a pale 

 orange color, all efforts to demonstrate the limiting membranes, 



FIG. 102. FIG. 103. 





FIG. 102. Red Corpuscles, shrivelled by the addition of strong syrup. 

 (w) White Corpuscle. 



FIG. 103. Blood-Corpuscles after the addition of tannic acid. 



formerly supposed to surround them, having failed. Their be- 

 havior when certain reagents are added to the blood shows that 

 the corpuscles have two constituents: (1) the coloring-matter, 

 Oxyhcemogtobin ; and (2) the Stroma. The coloring-matter may 

 be removed as above stated, by water from the corpuscles, and 

 then leaves a perfectly colorless transparent foundation or ground- 

 work, which appears to be in some way porous, so as to hold the 

 coloring matter in its interstices. The effect on the naked-eye 

 appearance of the blood produced by the removal of the coloring- 

 matter from the stroma, is to alter the color and increase tho 

 transparency of the fluid. The oxyhsemoglobin now forms a 

 transparent dark-red lakey solution, and the corpuscles, being 

 quite colorless, are practically invisible. This transparency of 



