BIOLOGY AND MORPHOLOGY. 237 



since been known as the Klebs-Loeffler baci]]ji. Loeffler's 

 findings have been verifiecrfty others, and Bacillus diphtheria 

 has been accepted as the specific cause of diphtheritic sore 

 throat. 



The bacillus is always present in the lesions of diphtheria, 

 and occasionally is found in the healthy throat and in the 

 throats of persons who have recently recovered from an attack 



FIG. 97. 



Bacillus diphtherias, from a culture upon blood-serum. X 1000. 

 (Fraenkel and Pfeiffer.) 



of diphtheria. Abbott cites the accidental occurrence of diph- 

 theria in one of his assistants who unintentionally sucked a 

 few drops of a virulent culture of the diphtheria bacillus 

 through a defective pipette, thus fulfilling all the require- 

 ments of Koch's law as to the specificity of any germ. 



Biology and morphology : The diphtheria bacillus (Figs. 96 

 and 97) is a rather thick rod, of about the length of the tubercle 

 bacillus and with a marked tendency to variation in form. 

 The rods may be straight or slightly curved ; of a uniform 

 size or irregular; pointed at one end and clubbed at the 



