EHRLICH'S " MASTZELLEN. 415 



in the compound ; to which may be added a small group of 

 " neutral " dyes. The basic dyes are in general nuclear 

 stains, that is, they exhibit a marked affinity for chroinatin, 

 as methyl green, for instance ; and are also in general 

 specific bacteria stains. The acid dyes have opposite affinities 

 and are in general plasma stains, as eosin, for instance. The 

 cell-granules in question have been classified by Ehrlich, 

 according to their respective degrees of affinity for one or the 

 other of these two groups of dyes, into (1) a granulations, or 

 eosinophilous granulations, being such as in a mixture of dyes 

 select the most acid stain there present ; (2) the )3 granula- 

 tions, or amphophilous granules, being such as in a mixture 

 of basic and acid dyes take up both ; (3) the 7 or basophilous 

 granules, being such as take up basic dyes only (such are the 

 granules of Mastzellen; (4) the granulations, also baso- 

 philous ; and (5) the e granulations, or neutrophilous granules, 

 being such as take up neutral anilin dyes, such as methyl blue 

 and " acid " fuchsin (acid f uchsin is a weakly acid dye). I do 

 not propose to enter minutely into the subject of these re- 

 actions, as it is one that cannot profitably be treated apart 

 from the histology of the elements in question, and will con- 

 fine myself to mentioning a few well-known methods. 



789. EHRLICH'S "Mastzellen" (Arch. f. mik.Anat., 1876, p. 

 263). First Method. Stain with neutral dahlia, and wash 

 out with acidified water, and mount as directed supra, 103. 

 If there be any Mastzellen in the preparation they will be 

 brought out by the superior energy with which they take the 

 stain. 



Second Method. It may be desirable to obtain a specific 

 stain of the plasma-cells alone, which may be done as 

 follows : 



The tissues must first be well hardened in strong alcohol 

 (chromic acid and its salts must be avoided). They are then 

 placed for at least twelve hours in a staining fluid composed 

 of 



Absolute alcohol .... 50 c.c. 



Aqua . ... . . . 100 c.c. 



Acid. acet. glacial . . . . 12^ c.c. 



to which has been added enough dahlia to give an almost 

 saturated solution. After staining, the preparations are 



