378 THE BLOOD AND THE BLOOD-FORMING ORGANS. 



thinj3HUifcJjflBiogem>ous protoplasm. The cell body usually possesses a 

 stronger basophUic^reacfelon than The nucleus, so that in staining with 

 methyleue blue the nucleus shows as a pale spot in the centre of the dark 

 ring of the cell body. This ring is often ragged in its outline and niay 

 show distinct projections which are sometimes cast off into the circulating 

 blood. Large and small lymphocytes may be distinguished (Plate II.. 

 Fig. 5). 



2. LARGE MONONUCLEAR LEUCOCYTES, with a single, compact or 

 vesicular, rather faintly staining nucleus and a relatively large amount 

 of protoplasm w^hich stains much less strongly than the nucleus, thus 

 separating this group from the lymphocytes. 



3. TRANSITIONAL LEUCOCYTES, of the same size as many of the large 

 mononuclear leucocytes, with a compact or vesicular, irregular or in- 

 curved nucleus, and a considerable mass of protoplasm, in which fine 

 neutrophile granules can occasionally be demonstrated. 



4. POLYNUCLEAR NEUTROPHILE LEUCOCYTES, of the same size as 

 the transitional leucocytes, with a partially or completely divided nu- 

 cleus, of which the separate portions are either compact or vesicular, 

 deeply or faintly staining, and with considerable protoplasm in which 

 distinct granules may be demonstrated by the neutral dyes. 



5. EOSINOPHILE CELLS, of the same characters as the ordinary poly- 

 nuclear leucocytes, but containing in their bodies large refractive gran- 

 ules w r hich stain deeply with so-called acid dyes such as eosiu. 



6. BASOPHILE CELLS, of about the same size as the polynuclear cells, 

 but containing coarse granulations stained only by basic dyes such as 

 methyleue blue. The nucleus is small, stains feebly, and is usually 

 lobular. It is often covered very largely by the granulations. 



These various forms of leucocytes occur in normal blood in the fol- 

 lowing proportions, which represent averages only and are subject to 

 considerable variations : 



Polynuclear neutrophile leucocytes TO to 72 per cent. 



/Large mononuclear and transition forms 2 " 4~^ " 



( Lymphocytes 22 " 25 < " 



Eosinophiles 2 " 4 J " 



Basophile cells less than 0.5 " 



In the normal blood of young children the relative proportion of 

 mononuclear cells is considerably greater than in that of adults. 



The numbers and proportions of the polynuclear leucocytes are in 

 disease subject to very wide variations, and some abnormal forms of 

 colorless cells make their appearance in the blood. 



Leucocytosis is that condition of the blood in which the leucocytes 

 are temporarily or persistently increased in number. When several 

 forms of leucocytes are increased in number and the usual proportions 

 are but partially disturbed, we speak of mixed, leucocytosis. Such a con- 



