MORPHOLOGY OF B. DIPHTHERIJE. 281 



like that of the bacillus of diphtheria that they might 

 easily be mistaken for that organism if subjected to 

 microscopic examination only. 



The bacillus diphtherice of Loffler (its discoverer) can 

 readily be identified by its cultural peculiarities in con- 

 nection with its pathogenic activity when introduced 

 into tissues of susceptible animals. In guinea-pigs and 

 kittens the results of its growth are identical with those 

 found in the bodies of human beings who have died of 

 diphtheria. 



When studied in pure culture, its morphological and 

 cultural peculiarities are as follows : 



Morphology. — As obtained directly from the 

 diphtheritic deposit in the throat of an individual sick 

 of the disease, it is sometimes comparatively regular 

 in shape, appearing as straight or slightly curved rods 

 with more or less pointed ends. More frequently, how- 

 ever, spindle and club shapes occur and not rarely many 

 of these rods take up the staining irregularly ; in some 

 of them very deeply staining round or oval points can 

 be detected. 



When cultures are examined microscopically it is 

 especially characteristic to find irregular, bizarre forms, 

 such as rods with one or both ends swollen, and very 

 frequently' rods broken at irregular intervals into short, 

 sharply marked segments, either round, oval, or with 

 straight sides. Some forms stain uniformly, others in 

 various irregular ways, the most common being the 

 appearance of deeply stained granules in a lightly stained 

 bacillus. 



By a series of studies upon this organism when cul- 

 tivated under artificial conditions, we have found that 

 its form depends very largely upon the nature of its 



