MORPHOLOGY 



539 



soil containing the tetanus bacillus, other organisms in addition to the latter 

 are found in the pus. Vaillard and Rouget isolated several of these organisms 

 and obtained cultures which when mixed with pure spores assisted in the 

 development of the disease just as would the addition of a negatively chemio- 

 tactic substance. Soil containing spores of tetanus only gives rise to the 

 disease provided that it contains such ancillary organisms. 



Experiment. Take a little soil containing tetanus spores and divide it into two 

 portions, one of which acts as the control. Mix the other portion with sterile water 

 and aspirate it into a pipette as far as the constriction. Seal the pipette and heat 

 the contents at 85 C. for an hour. The spores of tetanus can survive this temperature 

 while non-sporing organisms are destroyed. If, now, some of the unheated soil 

 be inoculated into guinea-pigs, the animals will die of tetanus, while guinea-pigs 

 inoculated with the same amount of heated soil will be unharmed. 



On the other hand cultures sown aerobically with the same (unheated) soil and 

 inoculated into guinea-pigs give rise to purulent lesions but never to tetanus. A 

 third series of guinea-pigs may be inoculated with 



a little of the heated soil to which a small amount f 



of an aerobic culture has been added. In this v 



case all the animals will die of tetanus. >J 





SECTION II. MORPHOLOGY. 



1. Microscopical appearance. 



The bacillus of tetanus occurs sometimes A 



as spores, sometimes in the non-spore-bearing ^ x 



condition. 



A. In young cultures, and in some cases in 



TYII flip nrrrnnim a<anmPQ f>iP fnrrn nf IT-PT-U- FlG. 259. Bacillus tetani. Pus from 



pus, tne organism assumes tne torm ol very a guinea . pig show ing a double infection 

 slender, elongated rods with square-cut ends with a coccus. Carboi-biue. (Oc. n, 

 measuring 3-4/u by 0'3-0'4/K, and showing in c 



the absence of oxygen slow wavy movements which cease when the bacillus 

 becomes spore-bearing. 



The non-spore-bearing bacillus is flagellated. The flagella are numerous, 

 wavy and long and are attached laterally to the body of the bacillus (peri- 

 trichous) (fig. 261). They can be readily stained by the usual methods 

 (p. 148). 



r 



Fm. 260. Bacillus tetani. Broth culture 

 showing spores. Carbol-fuchsin and methy- 

 lene blue. (Oc. 2, obj. T Uh, Zeiss.) 



FIG. 261. Bacillus tetani. Showing 

 flagella. x 1000. 



B. Spore-bearing bacilli will be found in cultures incubated at 37 C. for 

 36-48 hours and sometimes in pus. Cultures 10 days old consist almost 



