BACTERIUM XEROSIS. 407 



a. It is subjected to the following mixture for from 

 one to three seconds : 



Methylene-blue (Griibler's) 1 gramme. 



Alcohol (96 per cent.) 20 c.c. 



When dissolved, mix with 



Acetic acid 50 c.c. 



Distilled water 950 c.c. 



6. After thoroughly rinsing in water, it is stained for 

 from three to five seconds in vesuvin (Bismarck-brown), 

 2 grammes, dissolved in 1 litre of boiling distilled water, 

 filtered, and allowed to cool. It is again rinsed in water 

 and examined as a water-mount, or it may be dried and 

 mounted in balsam. 



When so treated the diphtheria bacterium appears as 

 faintly stained brown rods, in which from one to three 

 dark-blue granules are always to be observed. The 

 dark granules are at one or both poles of the cell, are 

 more or less oval, and usually seem to bulge a little 

 beyond the contour of the bacterium in which they are 

 located. (See Fig. 70.) From Neisser's observations 

 and those of others, 1 as well as from personal experi- 

 ence, it seems safe in the vast majority of cases to re- 

 gard all bacteria that do not stain in the way described 

 as distinct from bacterium diphtherise. 2 



Blumenthal and Lipskerow 3 decide that the differ- 

 ential method which yields the most satisfactory results 

 consists in the fixation of the preparation for from one- 



i Frankel : Berliner kiln. Wochenschrift, 1897, No. 50. 



sBergey: Publications of the University of Pennsylvania, New 

 Series, No. 4, 1898. 



a Blumenthal aud Lipskerow; Centraiblatt f. Bacteriologie, Bd. 

 xxxviii., p. 359, 



