208 CLINICAL BACTERIOLOGY AND HEMATOLOGY 



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. ii). 



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. lo). 



Cornirs myelocyte is probably derived from Ehrlich's by a 

 process of degeneration, especially dropsy of the nucleus. 



2. EosinopMle 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. 



■2a. Eosinophile myelocytes (Plate VII., Fig. 12) do not occur in 

 healthy blood, and bear the same relation to the eosinophile cells 

 as ordinary myelocytes to the polynuclear cells. They are dis- 

 tinguished from eosinophiles by their larger size and relatively 

 large circular nucleus. 



3. BasopMle Cells or Mast Cells (Plate VII., Fig. 9). — These are 

 about as large as polynuclears, and have twisted (usually trilobed) 

 nuclei, which occupy more of the cell than do those of the poly- 

 nuclears. They have a comparatively small number of granules, 

 which (unlike those of the other leucocytes) vary in size and stain 

 blue or purplish-blue with Jenner. The granules do not stain at 

 all with triacid. 



They are often not found in persons in robust health, but in the 

 average hospital patient occur in small numbers - usually less 

 than ^ per cent. 



3a. Large Mast Cells (Plate VII., Fig. 13). — These occur only in 

 the blood in myeloid leucocythaemia, and are very characteristic 

 of that condition. They may possibly be eosinophile myelocytes 

 with degenerated granules. 



