THE BLOOD AND LYMPH. 



125 



or to peculiarities in their behavior toward coloring-matters. The 

 best defined of these groups are : 



1. The polynuclear neutrophilic leucocytes, in which the nucleus 

 has a very irregular form, often presenting the appearance of two 

 or more nuclei, and the cytoplasm contains granules that have an 

 affinity for neutral anilin-dyes (Fig. 106, / and g). This variety 

 constitutes about 72 per cent, of the total number of leucocytes, and 

 is probably produced chiefly in the red marrow of the bones. They 



FIG. 106. 



a 



Leucocytes from normal human blood. (Bohm and Davidoff.) a, red blood-corpuscle, intro- 

 duced for comparison; b, small mononuclear leucocyte (lymphocyte); c, large mono- 

 nuclear leucocyte ; g, polynuclear leucocyte. These differ in the character of the granules 

 they contain (not represented in the figure). In normal blood those granules are neutro- 

 philic in the vast majority of the polynucleated leucocytes. Occasionally they are acido- 

 philic, "esinophile leucocytes"; sometimes basophilic, " mast-cells" or "plasma-cells." 

 d, e,f, intermediate and probably transitional forms between the large mononuclear leu- 

 cocytes c, and the polynucleated leucocytes, or leucocytes with polymorphic nuclei, g. 



possess the power of executing amoeboid movements and incor- 

 porating foreign particles. 



2. The lymphocytes, with a single round nucleus and a little clear 

 cytoplasm around it. These leucocytes are of about the same size 

 as the red blood-corpuscles (Fig. 106, b). They are derived from 

 the lymphadenoid tissue in the lymph-nodes and other situations, 

 and appear to be incapable of amoeboid movement. They constitute 

 about 23 per cent, of the total number of leucocytes in normal blood. 



3. The large mononuclear leucocytes, which are larger than the 

 red corpuscles and have oval nuclei surrounded by clear cytoplasm 

 (Fig. 106, c). This variety has also received the name " myelocyte," 

 on the probably correct assumption that they are derived from the 

 red marrow of the bones. They are capable of passing through 



