7 
Pathological Leucocytes 
1. Neutrophil Myelocyte. —15-20 ja. A mononu¬ 
clear leucocyte with, numerous neutrophil (e) granules. 
The nucleus is round or indented and stains feebly. 
Very common in myeloid leukaemia ; it is also found 
in the blood when there is a marked leucocytosis or in 
pronounced anaemias, e.g., of malaria (Fig. 3). 
2. Eosinophil Myelocyte. —As the former but with 
eosinophil (a) granulation. Found mainly in myeloid 
leukaemia and occasionally when the blood shews well- 
marked eosinophilia (Fig. 3). 
3. Mast Myelocyte. —As the former but with 
basophil (y) granules which stain, however, with watery 
stains. In myeloid leukaemia. 
4. Large Lymphocyte. —15-20^, i.e., slightly larger 
than large mononuclears. The nucleus is very large 
and round , stains feebly, but has one or two distinct 
nucleoli. There is a scanty rim of protoplasm shewing 
a fine basophil network. They are distinguished from 
large mononuclears by the round nucleus, by the 
nucleoli and by the narrow rim of protoplasm ; from 
the mature or old variety of normal lymphocyte by the 
fact that the nucleus is quite round and not oval or long 
and eccentric, by the difference in staining, and by the 
scanty, not broad, rim of protoplasm. Normally they 
occur as tissue cells in lymphatic glands and in the 
lymph follicles of the spleen. They occur in the blood 
in lymphatic leukaemia and allied conditions (Fig. 4). 
5. Myeloblast = lymphoid marrow cells.—10-20 fi. 
The nucleus is round or oval and stains deeply (not 
faintly as in the large mononuclear and older lympho¬ 
cytes) and a dirty grey-blue with triacid (not bluish 
green as the lymphocytes). The protoplasm is narrow 
and deeply basophil, more so than that of the large 
