BACILLUS TETANI 429 



mixture with other organisms. Infection of animals with such a culture 

 produced the disease. These results were confirmed by Rosenbach, who, 

 though failing to obtain a pure culture, cultivated the other organisms 

 present, and inoculated them, but with negative results. He further 

 pointed out, as characteristic of the bacillus, its development of terminal 

 spores. In 1889, Kitasato succeeded in isolating from the local suppura- 

 tion of mice inoculated from a human case, several bacilli, only one of 

 which, when injected in pure culture into animals, caused the disease, 

 and which was now named the b. tetani. This organism is the same as 

 that observed by Nicolaier and Rosenbach. Kitasato found that the 

 cause of earlier culture failures was the fact that it could only grow in the 

 absence of oxygen. The pathology of the disease was further elucidated 

 by Faber, who, having isolated bacterium-free poisons from cultures, 

 reproduced the symptoms of the disease. 



Bacillus Tetani. If in a case of tetanus naturally arising 

 in man, there be a definite wound with pus formation or necrotic 

 change, the bacillus tetani may be recognised in film preparations 

 from the pus, if the characteristic spore formation has occurred 

 (Fig. 124). If, however, the tetanus bacilli have not formed 

 spores, they appear as somewhat slender rods, without present- 

 ing any characteristic features. There is usually present in such 

 pus a great variety of other organisms cocci and bacilli. The 

 characters of the bacillus are, therefore, best studied in cultures. 

 It is then seen to be a slender organism, usually about 4 /x, to 

 5 JJL in length and '4 /x in thickness, with somewhat rounded 

 ends. Besides occurring as shorter rods it also develops 

 filamentous forms, the latter being more common in fluid media. 

 It stains readily by any of the usual stains and also by Gram's 

 method. A feature in it is the uniformity with which the 

 protoplasm stains. It is very slightly motile, and its motility 

 can be best studied in an anaerobic hanging-drop preparation. 

 When stained by the special methods already described, 

 it is found to possess numerous delicate flagella attached 

 both at the sides and at the ends (Fig. 125). These flagella, 

 though they may be of considerable length, are usually 

 curled up close to the body of the bacillus. The formation of 

 flagella can be best studied in preparations made from surface 

 anaerobic cultures (p. 70). As is the case with many other 

 anaerobic flagellated bacteria, the flagella, on becoming detached, 

 often become massed together in the form of spirals of striking 

 appearance (Fig. 126). At incubation temperature b. tetani 

 readily forms spores, and then presents a very characteristic 

 appearance. The spores are round, and in diameter may be 

 three or four times the thickness of the bacilli. They are 

 developed at one end of a bacillus, which thus assumes what is 

 usually described as the "drumstick" form (Figs. 124, 127). In 



