BACTERIOLOGICAL EXAMINATION 297 



reddish violet color, filling the entire protoplasm. The granulation owes this 

 color to the chemical action of a combination of the acid fuchsin and the 

 methylene-green produced by a " neutral " stain ; for this reason these granu- 

 lations are designated as neutrophilic, and this variety of cells as polynudear 

 neutrophilic leukocytes. As this granulation only stains in " neutral " dyes, 

 it remains unstained in the methylene-blue eosin mixtures that do not contain 

 a "neutral" dye stuff, and we therefore find in the polynudear leukocytes 

 in this stain an entirely unstained protoplasm, while the nucleus shows an 

 intense blue (IX, a). 



A small number of white blood-corpuscles by their staining and mor- 

 phology show a close relationship to the group described above; they only 

 differ in that the granulation is much more sparse, and that instead of a 

 polymorphic and intensely stained nucleus a larger, less indented, quite faintly 

 stained nucleus is present. These cells we designate as transitional forms 

 (see colored plate VIII, c). They are the stages immediately prior to the 

 polynudear neutrophilic leukocytes which in part are formed from the fol- 

 lowing groups : 



Large mononuclear leukocytes. This cell form is one which is most diffi- 

 cult to differentiate from the lymphocytes; nevertheless this differentiation 

 is absolutely necessary. In the triacid stain they are remarkable for their 

 size, being three times as large as a normal red blood-corpuscle. Their 

 nucleus is large, comprising about one-third of the cell, usually eccentrically 

 placed, round, of a pale green stain ; their protoplasm is almost unstained and 

 free of granulations (VIII, 6). The cells stained in methylene-blue (VIII, a) 

 are often decidedly more characteristic. We have one prominent sign which 

 greatly facilitates the differentiation of this variety of cells from the larger 

 forms of the lymph-cells; namely, that while (as has been mentioned above, 

 and as may be noted from the colored plate) in the lymphocytes the boundary 

 between the nucleus and the protoplasm is sharply marked, in the large mono- 

 nuclear leukocytes the dividing line is indistinct, so that frequently we cannot 

 determine where the nucleus begins and the protoplasm ends. The proto- 

 plasm of this cell variety is apparently never more decidedly basophilic than 

 its nucleus. 



The three last named cell forms constitute an intimately connected group, 

 that is, links in a chain of development the beginning series of which are the 

 large mononuclear leukocytes, and from these, by transformation and division 

 of the nucleus as well as by the extension of granulations, the transitional 

 forms and, later, the polynudear neutrophilic leukocytes, arise. 



The cell forms which in fresh blood are conspicuous by their coarse granu- 

 lations may also be readily differentiated from the others in the stained 

 preparation. Their nuclei stain with nuclear stains with medium intensity; 

 the granulations which almost completely fill the protoplasm in the triacid 

 solution are orange or copper color (X, h), and in eosin-containing solutions 

 they are stained a brilliant red (X. a) ; unfortunately, in the reproduction 

 they are not very well depicted. On account of this property of acid dyes 

 (especially eosin) to attract these granulations, the entire cell is called 

 oxyphilic, acidophilic or eosinophilic. 



