WHITE BLOOD CORPUSCLES 77 



and highly chromatic, deeply staining character as that of the 

 polynuclear neutrophile type. Their cytoplasm differs, however, 

 in that the intersections of the meshes of its cytoplasmic retic- 

 ulum are occupied by very coarse spheroidal granules which are 

 highly acidophile, and therefore stain deeply with such dyes as 

 eosin, erythrosin, and acid fuchsin. The cytoplasm of these cells, 

 exclusive of its specific granules, possesses a slightly acidophile 

 nature similar to that of the polynuclear neutrophile type ; this 

 peculiarity can be readily demonstrated, as in the former case, by 

 overstaining with acid dyes. Centrosomes and mitotic figures 

 have also been repeatedly demonstrated in these cells. 



Other coarsely granular cells basophile leucocytes possess a 

 considerable rim of cytoplasm containing very coarse basophile 

 granules. They are usually mono-, though frequently polynuclear. 

 They form about 0.5 per cent of the white blood cells, and can 

 therefore be disregarded' as a normal constituent of human blood. 

 In certain diseased conditions, notably in myelogenous leukemia, 

 they appear in the circulation in considerable numbers. 



None of the several forms of white blood cells possess a cell 

 membrane, and in marked contradistinction to most other cells of 

 the body the presence of a peripheral condensation of the cyto- 

 plasm (exoplasm) can not be demonstrated with any degree of cer- 

 tainty. 



The several varieties of white blood corpuscles found in normal 

 blood, with their prominent characteristics, may be summed up 

 as follows : 



. 1. Small mononuclear leucocytes or lymphocytes, with a non- 

 granular basophile cytoplasmic rim of insignificant breadth, and 

 a spheroidal deeply staining nucleus whose abundant chromatin 

 is characteristically clumped to form even more deeply staining 

 karyosomes. These cells are the smallest of the several types of 

 leucocyte, and they form from 22 to 25 per cent of the white blood 

 corpuscles in human blood.* 



2. Large mononuclear leucocytes with a considerable rim of 

 non-granular cytoplasm in which a slightly basophile reticulum 

 can be demonstrated. These cells possess a faintly staining vesic- 

 ular nucleus which is poor in chromatin ; it is typically sphe- 

 roidal in shape, but may be notched, indented, or even horseshoe- 



* These figures are those originally given by Ehrlich. In infancy the rela- 

 tive percentage of small mononuclear leucocytes is often greatly increased (50 

 per cent) at the expense of the polynuclear neutrophiles (40 per cent). 



