208 



BLOOD 



almost exclusive cell type of lymph. They take origin in the adult in 

 lymph organs, spleen and bone-marrow. In infancy their proportion is 

 much greater, about 50 per cent. ; this increase is at the expense of the 

 neutrophil granulocytes. 



Non-granular Leukocytes. These are characterized by a large, fre- 

 quently bean-shaped vesicular (clear, pale) nucleus, and an extensive 



FIG. 223. A GROUP OF CELLS FROM NORMAL HUMAN BLOOD. 

 /, red blood corpuscles in rouleau formation; 2, red blood corpuscles, surface 

 view; 3, lymphocyte; 4, large mononuclear leukocyte; 5, polymorphonuclear, 

 finely granular leukocyte; 6, eosinophil leukocyte; 7, a group of blood platelets; 8, 

 basophil leukocyte. Eosin-methylene blue. Basting's method. X 1200. 



shell of homogeneous faintly basophil cytoplasm. They constitute from 

 2 to 4 per cent, of the white cell total; they are notably phagocytic. 

 Occasionally a few larger neutrophilic cytoplasmic granules may be 

 present. Morphologically, both from the viewpoint of nucleus and cyto- 

 plasm, they are transitional between lymphocytes and granulocytes, 

 hence the use of transitional leukocyte as synonym for non -granular 

 or large mononuclear leukocytes. Modification of this cell, characterized 



