502 APPLICATION OF METHODS OF BACTERIOLOGY 



water and counterstaining with a 1 to 1000 solution of 

 vesuvin for one-half minute. By this method the polar 

 granules of bacterium diphtherias are stained bluish black, 

 are large, and may be seen in almost all of the organisms. 

 The contour of the darkly stained bacterium diphtherias 

 is sharply defined, and it is very easily differentiated from 

 any other organisms that may be present in the preparation. 



FIG. 83 



Bacterium diphtherias, stained by Neisser's method. 



NOTE. Prepare cover-slip preparations from the mouth- 

 cavities of healthy individuals and from those having decayed 

 teeth. Do they correspond in any way with those made 

 from diphtheria? Do the same with different forms of 

 sore-throat. Do the peculiarities of any of the organisms 

 suggest those of bacterium diphtherise? Wherein is the 

 difference ? 



In cultures and cover-slips made from both diphtheritic 



