

WHITE BLOOD-CORPUSCLES 85- 



To study the leucocytes of human blood after fixation, preferably with heat, 

 use the Ehrlich tricolor stain (p. 32) for five minutes ; wash, dry, mount 

 in balsam. The red corpuscles are stained orange -yellow to brown. The 

 nuclei of the leucocytes are stained green. 



The Ehrlich method of staining shows us that the leucocytes, 

 are of several kinds. Some have large, round nuclei; others- 



A B 



FIG. GO. VARIETIES OF LEUCOCYTES. 



A. Small Lymphocytes. 



B. Large Lymphocytes. 



C. Polymorpho-nuclear Neutrophiles. 



D. Eosinophile. 



have nuclei that are distorted or that appear to be in several 

 parts. Some have stained granules in their protoplasm; others 

 have no granules. The nature of the granules and their affinities 

 for the aniline dyes have been described in the chapter on staining. 

 The granules in the leucocytes of man are of two sorts: (a) Neu- 

 trophile granules, very small and numerous dust -like granules of 

 a reddish brown color; the leucocytes containing them look as 

 though they had been sprinkled with red pepper, (b) Eosinophila 

 granules good sized, round, shining granules, not so numerous 

 in the cells as the last. 



These characters enable us to classify leucocytes as follows: 



1. Small lymphocytes, which have a large, round nucleus and a 

 thin band of protoplasm with no granules. They are the same as 

 the lymphoid cells of the lymph- nodes and lymph from which they 

 originate. They make twenty per cent, to thirty per cent, of all 

 leucocytes. 



2. Large lymphocytes, or large mononuclear leucocytes. They 

 have a round or indented nucleus, and a considerable amount of 

 protoplasm, without granules. Those with indented nuclei are 

 often known as transitional forms. The large lymphocytes are 

 not numerous four to eight per cent. 



