SECTION I 



THE WHITE BLOOD-CORPUSCLES 



AMCEBOID cells are a constant constituent of the coelomic fluid in all 

 classes of animals. Even in the lower metazoa, where there is not yet a 

 body cavity, wandering mesoderm cells are present which apparently 

 discharge functions analogous in all respects to those of the white blood- 

 corpuscles of mammals. On carefully examining a specimen of human 

 blood, either fresh or in the form of a thin stained film, several varieties 

 of these cells are seen to be present. In a fresh specimen we can distinguish 

 the following varieties : 



(a) A cell with a lobed nucleus and finely granular protoplasm ; 



FIG. 359. Various forms of leucocytes. 



a, eosinophile corpuscle ; &, ordinary polynuclear leucocyte (' neutrophile ') ; 

 c, hyaline corpuscle ; d, lymphocyte. 



(6) A small cell consisting almost entirely of a nucleus surrounded by 

 a thin layer of protoplasm ; 



(c) A cell with a single nucleus and clear hyaline protoplasm ; 



(d) A cell with a lobed or reniform nucleus, the cytoplasm being beset 

 with large coarsely refracting granules. 



These four types are known as the finely granular or polymorpho- 

 nuclear cell, the lymphocyte, the hyaline corpuscle, and the coarsely 

 granular corpuscle. 



The differentiation of the various types of leucocytes is more easily 

 made if recourse be had to staining with mixtures of aniline dyes. This 

 method was introduced by Ehrlich, who classified leucocytes according to 

 the staining characters of their granules, dividing the latter into : 



(a) Those staining with acid dyes, such as eosin acidophile or eosino- 

 phile granulation ; 



(6) Those staining with basic dyes basophile ; 



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