200 



THE BLOOD 



1. Lymphocytes, are not granular 1 and do not show a very pronounced shifting 

 of their substance. 



(a) Small Type. These cells possess a small amount of cytoplasm and a 

 relatively large and symmetrical nucleus. They are about as large as the red 

 corpuscles and constitute about 25 per cent, of all the white corpuscles. 



(6) Large Type. These cells are much larger than the preceding and display a 

 broader margin of cytoplasm around a somewhat eccentric nucleus. They are 

 few in number and often exhibit a granular, irregularly stained network simu- 

 lating true granulations. 



2. Leukocytes, are granular and exhibit a very characteristic ameboid motion, 

 (a) Transitional Type. These cells are few in number (2 to 10 per cent.) 



and contain a large quantity of protoplasm in which a few neutrophilic granules 

 are suspended. The nucleus is shaped like a horseshoe or an hour-glass, but is 

 not divided into smaller masses. 



BET 



FIG. 109. DIFFERENT VARIETIES OF HUMAN WHITE CORPUSCLES. 

 A, lymphocyte; B, mononuclear leukocyte; C, transitional form; D, polynuclear 

 leukocyte; E, eosinophile leukocyte; F, mast-cell. (After Szymonowicz.) 



(b) Polymorphonuclear Type. The protoplasm of these cells is abundant 

 and embraces many fine neutrophile granules. The nucleus is lobulated, its different 

 segments being connected by strands. They form about 70 per cent, of the total 

 number of the leukocytes. To this group also belong the eosinophilic leukocytes 

 which, as the name indicates, stain with acid dyes, such as eosin. They are 

 characterized by their coarse and strongly refracting granules, and show a most 

 active ameboid motion. 



(c) Basophile Type. These cells are frequently called mast-cells. 2 They are 

 present in small numbers under normal conditions (less than 1 per cent.) and 

 embrace a nucleus consisting of two or three segments. Their granules stain 

 deeply with basic dyes, such as thionin. 



The Number of the White Corpuscles. It is generally given as 

 6000 to 10,000 per cu. mm., which figure indicates a proportion of one 

 white to about 700 red corpuscles. The total number of white cor- 



1 True granules are present in severe anemias, but rarely in health. 



2 Discovered by Bonders and Molischott in 1848; also see: Hirt, Dissertation, 

 Leipzig, 1855. 



