DIFFERENTIAL LEUCOCYTE COUNT 227 



into various irregular shapes ; it is often deeply lobed, so that it 

 appears to be multiple, but is always really single except in de- 

 generated forms. 



It contains in its protoplasm numerous very fine granules of a 

 substance which stains pink with the eosin in Jenner's stain, and 

 which are therefore considered by many English pathologists to 

 be fine eosinophile granules. With triacid stain they are a sort 

 of copper colour, quite unlike the large eosinophile granules, and 

 are frequently spoken of as neutrophile. The term is a convenient 

 one, whatever the scientific justification for it. 



They vary in numbers between rather wide limits. In the 

 adult 70 per cent, is a fair average, but they may be much higher, 

 and approach 80 per cent. In childhood they are much less 

 numerous (30 to 40 per cent.). 



la. Myelocytes or Neutrophile Myelocytes. — These are the mother- 

 cells of the above, and do not occur in the blood in health, but 

 may be found in the bone-marrow. There are two varieties. 



Cornil's myelocyte is usually a very large cell with a large, faint- 

 staining round or kidney-shaped nucleus, often placed decidedly 

 to one side of the cell or even touching the periphery. The pro- 

 toplasm is relatively scanty and contains neutrophile granules, 

 often in very small numbers and of feeble staining power. It is 

 often necessary to use triacid stain to demonstrate them ; neglect 

 to do this may lead to their being confounded with large lympho- 

 cytes or hyaline cells (Plate VII., Fig. 11). 



Ehrlich's myelocyte is similar to the above, but smaller ; it is 

 usually rather larger than a polynuclear. It has a round or oval 

 nucleus, which is often central or but slightly excentric, and which 

 stains deeper than that of Cornil's myelocyte, but not so deeply 

 as that of a polynuclear. Its neutrophile granules are usually 

 distinct (Plate VII., Fig. 10). 



Cornil's myelocyte is probably derived from Ehrlich's by a 

 process of degeneration, especially dropsy of the nucleus. 



2. Eosinophile Leucocytes (Plate VII., Fig. 8). — These are about 

 as large as a polynuclear, and have a nucleus which is usually 

 bilobed, but which may be more distorted. The chief feature of 

 the cell is the presence of numerous relatively large granules 

 which stain brilliantly with the eosin ; they are spherical in shape 

 and very uniform in size. They average about i to 4 per cent, of 

 the leucocytes in health, but slightly higher or lower figures may 

 occur. 



