CIRCULATORY SYSTEM. Iig 



Lymphocytes are small, mononucleated, white cor- 

 puscles, with a distinct staining nucleus and a very 

 narrow border of cytoplasm. Amoeboid motion is, 

 accordingly, much limited in this class. 



Large mononucleated leucocytes have a large vesic- 

 ular and usually eccentric nucleus. Its chromatin 

 occurs in scattered granules that stain less deeply 

 with nuclear stains, while the finely granular cyto- 

 plasm is usually abundant. These cells are gener- 

 ally regarded as phagocytic in function. 



Polynuclear cells are only slightly larger than the 

 red blood-corpuscles. The nuclei are often nodular, 

 polymorphic; that is, are united by slender constric- 

 tions, or are lobulated and of a variety of patterns. 

 In a small number of these cells basophilic granules 

 are found in the cytoplasm, which stains blue with 

 basic stains. These are the mast cells. Another 

 small group have eosin-staining granules, and these 

 are the eosinophiles. The large bulk of poly nucleated 

 white corpuscles have cy toplasmic granules that take 

 neither acid nor basic stains, and these are the neu- 

 trophiles. They are the white corpuscles found abun- 

 dantly in ordinary pus and the ones that produce a 

 general leucocytosis in such infections. 



The percentage of these different cells and their 

 total number per cubic millimeter is of the greatest 

 clinical value in blood analysis. They are often 

 called wandering cells, as they are able to pass 

 through the capillary wall and migrate throughout 

 the tissues and organs. The poly nucleated form is 

 readily recognized by multiple or fragmented nuclei. 



3. Blood platelets are small, colorless, round, non- 

 nucleated bodies about one-third the size of red 



