BACTERIUM XEROSIS 501 



(a) It is subjected to the following mixture for from one 

 to three seconds: 



Methylene-blue (Griibler's) 1 gram 



Alcohol (96 per cent.) . .*,./. >t 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 grams, dissolved in 1 liter of boiling distilled water, 

 filtered, ond 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 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. 83.) From 

 Neisser's observations and those of others, 1 as well as from 

 personal experience, it seems safe in the vast majority of 

 cases to regard all bacteria that do not stain in the way 

 described as distinct from bacterium diphtherise. 



Blumenthal and Lipskerow 2 decide that the differential 

 method which yields the most satisfactory results consists 

 in the fixation of the preparation for from one-half to two 

 minutes in the following solutions: Pyoktanin (Merck) 

 0.25 grams, acetic acid (5 per cent.) 100 c.c.; washing in 



1 Frankel, Berliner klin. Wochenschrift, 1897, No. 50. Bergey, Publica- 

 tions of the University of Pennsylvania, New Series, 1898, No. 4. 



2 Centralblatt f. Bacteriologie, Bd. xxxviii, p. 359. 



