1 92 NORMAL AND PATHOLOGICAL BLOOD 



There is not that sharp distinction between nucleus and cytoplasm 

 that exists in the lymphocytes. The cytoplasm of the large mononu- 

 clear gives the impression of opacity, as if it were frosted glass instead 

 of clear glass. The neutrophile mottling which begins to appear causes 

 a disappearance of the pure blue character of the cytoplasm of the 

 lymphocyte. It is principally by the washed-out staining of the nucleus 

 and the opaque lilac of the cytoplasm that we differentiate them from 

 the lymphocytes. They greatly resemble Tiirck's irritation forms or 

 plasma cells and may be confused with myelocytes. 



4. Transitionals. These appear as but a later stage in the decay 

 of the large mononuclears; the nucleus is more indented, frequently 

 horseshoe-shaped, and has a washed-out violet shade of less intensity 

 than that of the large mononuclears. These are the cells so often dis- 

 rupted in smears. 



These four kinds of cells are frequently referred to as the lymphocyte 

 series, and although many authorities consider that the small lympho- 

 cyte represents a more mature cell than the others of this class, yet it 

 is thought by others that the age of the cell increases as we go from small 

 lymphocytes to large lymphocytes, thence to the large mononu clear; 

 and then in the transitional we have the decrepit stage which precedes 

 dissolution. The old view that the transitional was the precursor of 

 the polymorphonuclear has few advocates at the present time. 



While it is convenient to consider these hyaline cells as representing 

 different stages in development, yet from a standpoint of immunity this 

 is untenable. The large mononuclears and transitionals are the cells 

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

 the case in malaria. These cells are the macrophages of Metchnikoff 

 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. 



Ehrlich and Naegeli regard the large mononuclears as of myeloid 

 origin while Pappenheim considers them to belong to the group of 

 lymphocytes. 



A normal percentage of large mononuclears and transitionals com- 

 bined should not exceed about 4%. 



In addition to the series of leukocytes just considered we have pres- 

 ent normally in the blood three types of granular cells distinguished 

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



