THE BLOOD CELLS (0 



from typical lymphocytes to monocytes are t'oiind, indicating their 

 source as the lymphocyte. 



Under conditions of chronic infiannnation, cells derived from 

 lymphocytes are present. These cells, called plasma cells, have an 

 eccentric nucleus in which the chromatin material radiates from the 

 center like the spokes of a wheel. 



Gr.\^ulocytes.— This group of cells shows a more restricted 

 development. The various tjT)es of cells constituting it are differ- 

 entiated as end-products and do not ])ossess the ability to multiply 

 or give rise to other cell types, as in the case of the agranulocytes. 

 The\' are formed in the bone-marrow or in other hemapoietic 

 centers and are all about the same size. On the basis of the reaction 

 of the cytoplasmic granules to certain stains three types of granulo- 

 cytes are differentiated, namely, neutrophils, eosinophils, and 

 basophils. 



Neutrophils ( Ilctewphils) .— Amon^ the mammals these cells are 

 a little larger than the red cells, while in the lower forms they may 

 be snuiller. The cytoplasm is filled with numerous uniformly small 

 granules. In man they are neutrophilic, staining a lavender color, 

 but in lower forms they may take either acid or basic, or both acid 

 and basic dyes. The nucleus is ])olymorphic, with several small 

 deeply staining lobes connected by thin strands of nuclear material. 

 Neutrophils are the most motile of the granulocytes. The\' are 

 markedly phagocytic for many bacteria, and when thus actively 

 engaged are called microphages. Great numbers are found in areas 

 of infection and numerous dead neutrophils appear in pus, though 

 they do not normally occur extra\ascularl\-. They are formed 

 mainly in the bone-marrow or in other hemapoietic centers. 



Eosinojjhils.— These cells have less polymorphic or even spherical 

 nuclei that are lightly staining. The cytoplasm contains numerous 

 uniformly large acidophilic granules. P'osinophils are less motile 

 than neutrophils, have but a slight phagocytic action for bacteria, 

 and are often found extravascularly. They are found in increased 

 numbers in cases of i)arasitism by worms and under other circum- 

 stances that \m\e led to the conclusion that they have a role in 

 detoxification and in allergic conditions. In some forms, such as 

 cats, rats and mice, eosinophils appear to be absent. 



Basophils.— In these cells the nucleus is slightly lobed or spherical, 

 it stains faintly, and is located centrally. The cytoplasm contains 

 large variable basophilic granules, usually less numerous than those 

 of either neutrophils or eosinophils. This type of cell is extremely 



