GRANULAR LEUKOCYTES. 159 



cells in which we find certain animal cells and pigment phagocytized, as 

 is the case in malaria. These cells are the macrophages of Metch- 

 nikoff and are probably derived from the bone marrow. 



The lymphocytes take origin from the lymphoid tissue, and very 

 probably the large lymphocyte is a younger, more immature cell than 

 the small lymphocyte. Consequently, we probably have marrow 

 lymphocytes and gland lymphocytes. 



In addition to the series of leukocytes just considered we have 

 present normally in the blood three types of granular cells distinguished 

 according to the staining affinity of their granules. These are : 



1 . Polymorphonuclear leukocytes. This cell normally constitutes 

 the greater proportion of the leukocytes. It is an amoeboid, actively 

 phagocytic cell, about 10 or i2/x in diameter, and is the microphage of 

 Metchnikoff. Bacteria are actively phagocytized by this cell, and it is 

 the cell concerned in determining the opsonic power of blood to various 

 bacteria. It has fine lilac granules which are termed neutrophilic. 

 (epsilon granules). The single nucleus is rich in character and is 

 lobose like the kernel of an English walnut; frequently it resembles the 

 letter z. These cells are derived from the neutrophilic myelocytes of 

 the bone marrow. It is in these cells that the glycogen, or iodophil, 

 granules appear in certain suppurative conditions. 



2. Eosinophile Leukocytes. These are very striking cells with 

 coarse granules staining brilliantly pink, the eosinophile, oxyphile or 

 acidophile granules (alpha granules of Ehrlich). The cells are a little 

 larger than the polymorphonuclears. The normal eosinophile is to be 

 distinguished from the eosinophilic myelocyte by its possessing two 

 distinct lobes in the nucleus. The nucleus of the myelocyte is round. 

 The eosinophile is the cell so frequently increased in infections by 

 intestinal animal parasites. 



3. Mast Cells. These also have coarse granules, but they stain 

 a deep violet blue. Hence they are basophile granules (gamma 

 granules). In fresh blood these granules do not show up very 

 well, thus they can be distinguished from the highly refractile 

 granules of the eosinophile. The-tri-lobed nucleus stains less intensely 

 than the granules. As a rule, the mast cell is about the size of a 

 pol\ morphonuclear. 



