THE SPORE-BEARING RODS 357 



form in bacteria thrown off in bloody exudate or in the 

 feces. In some cases, particularly in the southern United 

 States, bloodsucking flies have been found to be of impor- 

 tance in transmitting the disease by direct inoculation. 



CLOSTRIDIUM TETANI 



Synonyms. Plectridium tetani, Bacillus tetani. 



This organism is the cause of disease tetanus or lockjaw 

 in man and many species of domestic animals. It was first 

 observed by Nicolaier in 1885, who isolated it from animals 

 that had died as the result of the injection of garden soil. 

 The organism was cultivated in pure culture by Kitasato, 

 who noted that it was an obligate anaerobe, that is, it will 

 not grow in the presence of free oxygen. 



This organism is not an obligate pathogen. It appears 

 that it, in common with other members of the genus 

 Clostridium, grows in the alimentary tract of animals, par- 

 ticularly of the horse, and only under exceptional conditions 

 is able to produce disease. It has long been noted that the 

 Clostridium tetani is found most frequently in soils which 

 have been heavily manured. It is possible that it may main- 

 tain a saprophytic existence and even multiply to some 

 extent in soil under favorable conditions. 



Morphology. Clostridium tetani is a slender rod .5ju X 

 2-5/x in length, with rounded ends. Usually it occurs in 

 short chains; it is actively motile in young cultures by 

 means of numerous peritrichic flagella. Spores are pro- 

 duced in abundance. The spore is terminal, spherical or 

 approximately spherical and greater in diameter than rod 

 which produces it. This gives a characteristic drum-stick 

 appearance. There are but few other bacteria, and these 

 closely related forms, which can be confused upon micro- 

 scopic examination with this organism. It stains readily 

 with the usual aniline dyes and is Gram-positive. 



