Leukaemia of the Fowl. 23 



polychromatophilia, mostly associated with a swelling of the nucleus 

 and separation of its chromatin (6). 



2. Normoblast (c) : Eound, diameter less than length of normal 

 normocyte. Nucleus round, of same color or slightly purple, but larger 

 and with more scattered chromatin than nucleus of normal normocyte. 

 Cytoplasm greenish-blue and glassy. Frequently with clear zone about 

 nucleus. 



3. Megaloblast (d) : Same, except diameter equal to or greater than 

 length of normal normocyte. 



4. Mitotic Cells (e) : All stages, from monaster to complete division 

 of nucleus, (a) Eound or elliptical, diameter about length of normal 

 normocyte. Dense, deep blue chromosomes, massed in center of cell. 

 Cytoplasm greenish-blue and glassy, (b) Same, with two masses of 

 chromosomes in opposite extremes of cell, (c) Same (at times with a 

 slight constriction in the middle of the cell) with irregular, dense, deep 

 blue or slightly purple chromatin masses in place of individual chromo- 

 somes, (d) Same, with two nuclei, similar in appearance to those of 

 normoblast. (e) Same as normal normocyte with two nuclei, similar in 

 appearance to those of normoblast, but only slightly larger than nucleus 

 of normal normocyte. (a), (b), (c) and (d) may show polychroma- 

 tophilic cytoplasm. 



Blood Platelets (/). 



1. Same as normal, except that cell and nucleus are both larger. 



2. Larger than normal with two nuclei. 



Leucocytes. 



1. Polymorphonuclear leucocyte with eosinophilic rods (g) : Same 

 as in normal blood, at times possibly a little smaller. 



2. Polymorphonuclear leucocyte with eosinophilic granules (h) : 

 Same as in normal blood, at times possibly a little smaller. 



3. Lymphocyte (i) : Same as in normal blood. 



4. Large mononuclear cell : (a) As described in normal blood, with 

 a little less cytoplasm, (b) Same size to one half times larger than (a), 

 with both nucleus and cytoplasm paler (/). (a) and (b) cannot be 

 separated absolutely. Every gradation, (c) Mitoses (fc) : All stages, 

 from monaster to complete separation of nucleus, (a') Elliptical, 

 diameter about one and a half length of normal normocyte. Dense, 

 purple chromosomes centrally massed. Cytoplasm pale bluish-gray, 



