II.] STRUCTURE OF BLOOD. 39 



several dark granules; a granular nucleus, 

 often irregular or lobed, comes into view, 

 usually more than one nucleus will be seen. 



b. In the red corpuscles the nucleus be- 

 comes obvious; it is when first seen nearly 

 homogeneous, and oval in outline, later 

 it becomes granular and usually irregularly 

 rod-shaped. 



c. The red corpuscles swell up owing to absorp- 

 tion of water, most after a time become 

 spherical (if strong acid be used the cor- 

 puscles usually preserve their shape). 



d. They become colourless, the colouring matter 

 being dissolved; occasionally the colouring 

 matter is massed round the nucleus before 

 complete solution takes place (effect of water) 

 and occasionally the nucleus becomes stained 

 yellow by the colouring matter (effect of acetic 

 acid). 



e. Finally the outline of the corpuscles is seen 

 as a faint line at some distance from the 

 nucleus. Observe the not infrequent excen- 

 tric position of the nucleus. 



/. Some corpuscles are much more readily 

 acted on than others. 



5. Irrigate with a strong aqueous solution of 

 Spiller's purple or magenta, 



a. The outline of the red corpuscle becomes 

 distinct, its nucleus stains deeply, around 

 the nucleus a little faintly stained granular 



