408 INFECTION AND IMMUNITY. 



consider them as diphtheria bacilli which have lost 

 their virulence. 



The presence of these organisms may complicate 

 the diagnosis of diphtheria in some cases, but 

 there is little danger of serious error. If one 

 found organisms resembling the bacillus of diph- 

 theria in a membranous sore throat which was ac- 

 companied by severe symptoms, there could be no 

 wavering in the decision to use antitoxin. 



II. TETANUS. 



In 1884 Carle and Eattone demonstrated the 

 infectiousness of tetanus by inoculating the pus 

 from an infected wound into rabbits; 11 of the 12 

 inoculated rabbits died of tetanus. In 1885 the 

 bacillus was discovered by Nicolaier, and Kitasato 

 cultivated it artificially in 1889. 

 character- The organism is rather long and slender (2 to 

 4 microns long, 0.3 to 0.5 broad), possesses many 

 ism. flagella and has a small amount of motility. It 

 stains readily with the ordinary anilin dyes and by 

 Grain's method. In young cultures isolated cells 

 and threads predominate,, but after a few days 

 spore formation begins; eventually all the adult 

 cells degenerate and the culture consists entirely 

 of spores. The spores have a larger diameter than 

 the bacillus, are situated at one end of the cell and 

 give the latter the characteristic "drumstick" 

 form. The organism is a strict anaerobe and is 

 obtained in pure culture with some difficulty. 

 Morphologically it is difficult to distinguish from 

 the bacilli of malignant edema and symptomatic 

 anthrax. 



Habitat. Few organisms are distributed more widely and 

 generously than the bacillus of tetanus. It is most 



