WHITE CORPUSCLES. 



147 



centrosome, or a group of its minute subdivisions, has been found in the 

 concavity of the nucleus. A delicate cell membrane has been described, 

 but membranes are usually considered lacking in all forms of leucocytes. 

 A fundamental characteristic of polymorphonuclear leucocytes is the devel- 

 opment of distinct granules in their protoplasm. These are more definite 

 structures than occur in ordinary protoplasm, so that lymphocytes together 

 with the large mononuclear cells are considered non-granular. Not only 



IL 



IIL 



FIG. 171. THE BLOOD CORPUSCLES. (WRIGHT'S STAIN.) (E. F. Faber, from 



Da Costa's Clinical Hematology.) 



I, Red corpuscles. II, Lymphocytes and large mononuclear leucocytes. Ill, ^eutrophiles. 

 IV, Eosinophiles. V, Myelocytes (not found in normal blood). VI, Mast cells. 



do the granules differ in size but also in staining reaction as may be seen 

 by employing the 'blood stains.' A drop of blood is spread thinly on a 

 cover glass and dried, afterwards being stained with a mixture of acid 

 and basic dyes. The details of nuclear structure are not preserved, but 

 the granules are clearly differentiated. With several of the blood stains 

 the fine granules stain purple or lilac and the coarse ones are red in some 

 cells and blue in others. Only one sort of granule occurs in a single cell. 

 Figure 171 shows corpuscles from such a preparation. 



