TETANUS 117 



horse, ox, sheep, and goat are the most susceptible, and it has also 

 been observed in the pig and dog. Chickens are immune. Nicolier 

 produced tetanus in mice and rabbits by subcutaneous inoculation 

 with particles of garden earth in 1884 ; and Kitasato cultivated the 

 bacillus of tetanus in pure cultures in 1889. 



Microscopical Appearances. The tetanus bacillus is a slender rod 

 with rounded ends 3 to 5 ft long, and 0*3 to 0'5 //, wide, and may appear 

 as single rods, or in cultures as long threads. 



Motility. Motile, although not actively so ; the flagella are attached 

 somewhat similarly to those of the bacillus of malignant oedema (see 

 Photomicrograph, Plate I., Fig. 6). 



Staining Reactions. It stains with the ordinary aniline reagents, 

 and by the Gram and Cladius methods. 



Spore Formation. At 37 C. spores are formed in thirty hours, 

 and at room temperature in about a week. The spores are situated at 

 one end of the rod, and have a diameter of 1 to 1'5 /A, giving the rod 

 the appearance of a drumstick (see Photomicrograph, Fig. 43, x 1300). 



Excluded from air and light, the spores in a culture remain living 

 and virulent for over a year. They can also resist heating to 80 C., while 

 exposure to steam at 100 C. kills them in five to eight minutes. They 

 resist the action of 5 per cent, carbolic acid tor ten hours, but succumb 

 when exposed for fifteen hours ; but if - 5 per cent, hydrochloric acid is 

 added they are no longer active in two hours. Corrosive sublimate 1 to 

 1000 kills them in three hours, and when 0'5 per cent, hydrochloric 

 acid is added they are killed in thirty minutes. 



Biological Characters. The tetanus bacillus is anaerobic. Recent 

 observations, however, point to the possibility of it having an aerobic 

 existence (Flugge). It grows well in an atmosphere of hydrogen, but 

 not in carbonic acid. 



Kitasato was the first to isolate the bacillus in pure cultures, and the 

 following is the method he adopted. 



Method. Inoculate several white mice from the secretions from a 

 wound in a typical case of tetanus. The material usually contains other 

 organisms besides tetanus bacilli, causing more or less suppuration at the 

 seat of inoculation in the mice. 



To separate the tetanus bacillus from others present, smear the pus 

 upon several oblique serum and agar-agar tubes, and place at 37 to 38 C. 

 After twenty-four hours all the organisms will have developed, and 

 microscopic examination will reveal the presence of a few tetanus bacilli, 

 recognisable by their shape, like a small pin, the spore representing the 

 head. After the culture has remained forty-eight hours at 38 C., it is 

 subjected to a temperature of 80 C. in a water-bath for from three- 



