NORMAL VARIETIES OF LEUCOCYTES 31 



Variety I. Lymphocytes. This variety includes cells usually 

 about the size or smaller than the average red corpuscle. Each 

 has a relatively large nucleus that occupies nearly all of the cell. 

 The nucleus is usually round but may be incurved or show a deep 

 notch or sinus at one side. The cell body usually shows as a nar- 

 row rim about the nucleus. Both nucleus and cell body are coarsety 

 reticular. With careful staining a nucleolus may be seen. The 

 cell body has a strong affinity for basic stains, often staining a 

 deeper blue with Jenner's stain than the nucleus. With Wright's 

 stain the cell body has a greenish blue while the nucleus has a dark 

 violet tint. Cells falling in this group have practically the same 

 appearance in the several domesticated animals. 



Variety II. Large mononuclears (hyaline cells, Kanthack and 

 Hardy; large monocytes, Pappenheim). Cells belonging to this 

 variety are larger than those of Var. I, usually about twice the 

 diameter of the average red corpuscle. The nucleus usually oc- 

 cupies only about one-half of the cell and is situated at one side 

 of the center. Its shape is oval or curved (kidney or horse-shoe 

 shaped). Both nucleus and cell body are finely reticular and stain 

 less deeply than do those of lymphocytes. The cell body is faintly 

 basophile. These cells have much the same appearance in the 

 several species of the domesticated animals. In the guinea pig, 

 however, a large number of cells of this variety contain within the 

 cell body one or more rounded bodies that are in some cases ap- 

 parently clear vacuoles and in other cases appear as homogenous 

 or occasionally reticular bodies (see Plate I, Fig. 11) of a purplish 

 tint with Wright's or Jenner's stains. They vary from about one 

 micron in diameter to a body occupying nearly one-half the cell. 

 The true nature of these bodies is not certainly known. Kurloff, 

 who first described them, regarded them as vacuoles containing a 

 secretory product. That they are products of secretion or de- 

 generation has been followed, at least passively, by the majority 

 of those who have written on the subject (Burnett, '04, Staubli, '06, 

 Howard, '07, and Canavan, '12). By some, however (Ledingham, 

 '06), the bodies are regarded as possibly organisms, parasitic in 

 nature. 



In the majority of instances there is no difficulty in distinguish- 

 ing the cells belonging to Var. I and Var. II, but a certain number 

 of intermediate forms do occur. In fact one can find all stages 



