THE BACILLUS OF TETANUS. 4Q1 



nor is any other neutralized by tetanus antitoxin. The 

 other characteristics also of this bacillus are usually dis- 

 tinctive, though microscopical examination alone cannot 

 be depended on to make a differential diagnosis. Diffi- 

 culty arises when other anaerobic or aerobic bacilli, 

 almost morphologically identical with the tetanus 

 bacillus, are encountered which are non-pathogenic, 

 such as the bacillus pseudotetanicus anaerobius, already 

 mentioned, and the bacillus pseudotetanicus aerobius. 

 It is possible, however, that both these bacilli, when 

 characteristic in cultures, are only varieties of the 

 tetanus bacillus, which, under unfavorable conditions of 

 growth, have lost, their virulence. These non-virulent 

 types do not, as a rule, have spores absolutely at their 

 ends, and the spores themselves are usually more ovoid 

 than those in the true tetanus bacilli. 



26 



