8 DISEASES OF DOMESTICATED BIRDS 
Small mononuclear leucocytes (lymphocytes) ........ 40 
Large mononuclear leucocytes ......+. sess eee eeeeers 18 
Polymorphonuclear leucocytes ......+.-eeeeee eee 35 
Eosinophiles  ......c. cee cee ccc cece cee cen cnn eeeeere 4 
Mast cells? aciecs asucessabitee Wen es tetas ae elece eee 3 
Lymphocytes. In these blood cells the nucleus is rounded or 
oval and almost completely fills the cell. It stains a deep blue with 
Giemsa. The narrow band of cell body stains a lighter blue and is 
not readily differentiated from the nucleus by ordinary staining. 
The lymphocytes are from 5 to 7 microns in diameter. 
Large mononuclears have a round or oval nucleus surrounded 
by a well defined border of cell protoplasm. The nucleus takes a 
deep blue stain, the cell body a pale blue. The cell diameter is 
10 to 15 microns. 
Polymorphonuclears have the appearance of having several nu- 
clei held together by threads or nuclear bands. They contain con- 
siderable protoplasm inclosing rod shaped or rounded granules. The 
nucleus stains blue, the protoplasm, a lighter color and the granules 
violet or brownish red with Giemsa’s stain. Diameter, 10 to 15 
microns. 
Eosinophiles have an irregular nucleus. The cell protoplasm 
is filled with rounded granules which stain a bright red with Giemsa’s 
stain. The nucleus takes a blue stain and the cell body a pale blue. 
Diameter, 12 microns. 
Mast cells have a lobulated nucleus which stains a deep blue. 
The cell protoplasm takes a pale stain. The granules are small and 
rounded and stain a dull violet with Giemsa and a deep blue with 
methylene blue. Diameter, 8 to 10 microns. 
Other blood cells of less importance which may be observed are 
as follows: 
Blood platelets are small colorless dises with granular centers. 
They are 3 to 4 microns in diameter and are usually found in small 
heaps of 6 to 8 cells. 
Shadow cells contain a rounded or broad oval nucleus which 
takes a deep blue stain. The cell body is colorless and not well de- 
fined or irregular in outline. These apparently represent red blood 
corpuscles undergoing degeneration. The stroma of the corpuscle 
loses its pigment, becomes colorless and gradually disappears leaving 
the nucleus partially or wholly separated. They are especially nu- 
merous in pathologic blood. 
Microblasts and macroblasts are found in the blood of young 
