DIFFERENTIAL LEUCOCYTE COUNT 207 



The small forms are the more numerous, but as no trustworthy- 

 diagnostic information can be drawn from the proportions of the 

 large and small forms, they are usually counted together. Very 

 large forms are often abundant in acute lymphatic leucocy- 

 thsemia. 



Large Hyaline or Large Mononuclear Leucocytes (Plate VII., 

 Figs. 5i 6). — These are the largest cells met with in normal 

 blood, and may have a diameter two and a half that of a red 

 corpuscle. They have a round, oval, kidney-shaped, or twisted 

 nucleus, which stains less deeply than those of the lymphocytes, 

 and has often a purplish colour. The protoplasm is relatively 

 more abundant than in the lymphocytes, and stains very faintly 

 of a bluish or purplish colour. It often has false granules similar 

 to those of lymphocytes, but no true ones. 



It occurs in small numbers (i to 4 per cent), and variations are 

 of little diagnostic importance. 



B. Cells containing True Granules in their Protoplasm. 



I. Polynuclear Leucocytes (Plate VII., Fig. 7). — These are rather 

 larger than a red corpuscle, and have a nucleus which is twisted 

 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 sid§ of the cell or even touching the periphery. The pro- 



