BACILLUS DIPHTHERIA 



513 



and it is to-day a scientific necessity to find the bacillus of Klebs and 

 Loeffler in the lesion before a diagnosis of ''diphtheria" can properly 

 be made. 



Morphology and Staining. While Bacillus diphtherias presents 

 certain characteristic appearances which facilitate its recognition, it is, 

 at the same tune, subject to a number of morphological variations with 



FIG. 105. BACILLUS DIPHTHERIA. 



all of which it is important to be familiar. These variations are, to a 

 limited extent, dependent upon the age of the culture and upon the: 

 constitution of the medium on which it has been grown. These 

 factors, however, do not control the appearance of the organism with 

 any degree of regularity, and any or all of its various forms may occur 

 in one and the same culture. It is likely that these different appear- 

 ances represent stages in the growth and degeneration of the indi- 

 vidual bacilli, but there does not seem to be any just reason for 

 believing that, as several observers have stated, there is definite correla- 

 tion between its microscopic form and its biological characteristics, such 

 as virulence, toxicity, etc. 



