ISOLATION OF THE BACILLUS 



421 



methylene-blue, the spores are uncoloured except at the periphery, 

 so that the appearance of a small ring is produced ; if a powerful 

 stain such as carbol-fuchsin be applied for some time, the spores 

 become deeply coloured like the bacilli. Further, especially if 

 the preparation be heated, many spores may become free from the 

 bacilli in which they were formed. 



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. 7 'v /ZtJ£*^ 



A 



Fig. 119. — Film preparation of discharge from wound lin a case 

 of tetanus, showing several tetanus bacilli of "drumstick" form. 

 (The thicker bacillus present is not a tetanus bacillus, but a 

 putrefactive anaerobe which was obtained in pure culture from the 

 wound.) 



Stained with gentian-violet, x 1000. 



Isolation. — The isolation of the tetanus bacillus is somewhat 

 difficult. By inoculation experiments in animals, its natural 

 habitat has been proved to be garden soil, and especially the 

 contents of dung-heaps, where it probably leads a saprophytic 

 existence, though its function as a saprophyte is unknown. It 

 also occurs in the dust of houses, on the skin and in the 

 intestines of many — especially of herbivorous — animals. From 

 such sources and from the pus of wounds in tetanus, 



