The hygiene of transmissible diseases; their causation, modes of dissemination, and methods of prevention . as been detected in the soil ofmany localities. It is pretty generally distributed in theupper layers of the earth, though in some places it is muchmore numerous than in others. It can usually be demon-strated in the soil of gardens that are fertilized with animalmanure. These facts explain the occasional onset of tetanus 156 HYGIENE OE TRANSMISSIBLE DISEASES. after wounds into which earth has gained access, such forinstance as punctured or lacerated wounds of the feet andhands by old ru
The hygiene of transmissible diseases; their causation, modes of dissemination, and methods of prevention . as been detected in the soil ofmany localities. It is pretty generally distributed in theupper layers of the earth, though in some places it is muchmore numerous than in others. It can usually be demon-strated in the soil of gardens that are fertilized with animalmanure. These facts explain the occasional onset of tetanus 156 HYGIENE OE TRANSMISSIBLE DISEASES. after wounds into which earth has gained access, such forinstance as punctured or lacerated wounds of the feet andhands by old rusty nails, wooden splinters ; crushed woundsfrom the wheels of wagons, carts, etc. It is a motile, spore-forming, anaerobic bacillus that pos-sesses the morphological peculiarity, when in the spore-stage,the only condition by which it is recognizable microscopically,of presenting the appearance of a small pin—/. c, the oval,glistening, unstained spore occupies one end of the rod, andserves as the head, while the slender stained body of thebacillus forms the rest of the pin-shaped structure (Fig. 18).. Fig. 18.—Bacillus tetani from artificial culture. The spores of bacillus tetani are very tenacious of are not destroyed by drying, even by absolute dryingin the dessicator, for months. They are killed in five min-utes by steam at 100° C, but they resist moist heat at 80°C. for one hour. They are not destroyed by immersion in 5per cent, carbolic acid for ten hours, though they are killedin fifteen hours by this treatment. The vegetative form of the organism as studied in pureculture is found to be by no means so resistant to detrimentalagencies as are the spores. As it is an obligate anaerobe (not growing in the presence TETANUS. 157 of free oxygen), it requires special methods for its isolationand cultivation. (See works on Bacteriology.) After the subcutaneous inoculation of mice, rabbits, andguinea-pigs with pure cultures, with particles of earth, withsecretions
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