VARIETIES OF LEUCOCYTES. 419 



readily than by basic, or vice versa. Thus, ordinary fuchsin 

 is hydrochlorate of rosaniline ; in this compound it is the 

 base, the rosaniline, which is the staining principle, the 

 acid, hydrochloric acid, is not the staining principle ; the 

 staining solution is therefore in Ehrlich's sense a basic 

 one (9). Again, picrate of ammonium is an " acid " dye, 

 because in it the picric acid is the staining principle. 

 Ehrlich terms the cell-granules which can be more readily 

 tinged with acid dyes, " oxyphil granules " ; those which 

 can be more readily tinged with basic dyes, "basophil". 



The technique introduced by Ehrlich and his pupils in 

 their researches of this kind is reliable and capable of wide 

 application. In its employment it is, however, necessary 

 to remember that it is not the living cells which are usually 

 dealt with, and that in the course of fixation the cells and 

 their granules become modified. It is therefore necessary 

 to adopt some particular mode of fixation and of application 

 of the stain as a standard, and thus to obtain standard 

 oxyphil and basophil reactions. Kanthack and Hardy (2) 

 proceed as follows : thin films of blood or lymph upon 

 cover-glasses are dried in the air, and then passed quickly 

 three times through a Bunsen flame. The films are next 

 placed for 30" in a solution of 5 grm. eosin in 100 c. cent. 

 of 70 per cent, alcohol. The excess of eosin is then 

 removed by placing the film in water, after which the film 

 is again dried, passed thrice through the flame, and finally 

 counterstained with Lofrler's methylene blue solution (basic 

 stain). 



Examined in this way there are found among wandering- 

 cells two kinds with oxyphil granules, and two kinds with 

 basophil granules. The cell with small oxyphil granules is 

 that which I have placed first on our list. It may be con- 

 sidered kut t£,o^rn> the wandering cell of mammalian blood. 

 The cell is of medium size, about 10 fi ; its cell-substance 

 contains small granules slightly more refracting than the 

 ground substance in which they lie ; the granules are 

 particularly obvious in the rabbit. The nucleus is peculiar 

 m form and fairly characteristic as distinguishing the cell 

 from other leucocytes. It is multipartite and of extremely 



