PRINCIPLES OF VETERINARY SURGERY 43] 



In a closed vessel and humid environment they are des- 

 troyed in fifteen minutes at lOO degrees and in five minutes 

 at 115 to 120 degrees. When dried up in the atmosphere 

 away from sunlight they remain virulent for years. They 

 are, however, very sensitive to light, especially sunlight, 

 which promotes oxidation, and will perish after about a 

 month's exposure. Before they die they progressively lose 

 their virulence and become incapable of forming spores. 

 In artificial cultures, the action of oxygen will also arrest 

 sporulation. 



Kitasato has shown that tetanus bacilli will resist car- 

 bolic acid, five per cent, for more than ten hours; that it 

 requires more than three hours for mercuric chloride, i to 

 1,000, to kill them, and that chloroform destroys them only 

 after two days. Nitrate of silver, i per cent, destroys them 

 in one minute ; iodine solution, 50 per cent, carbolic acid, 

 50 per cent, and permanganate of potash, i per cent, will 

 destroy the activity of the spores after some minutes' con- 

 tact. In the soil the spores of tetanus may find conditions 

 which will preserve their virulence for a long time. They 

 are especially well preserved when in an albuminous envi- 

 ronment. Eiselsberg has proven that a splinter taken from 

 the hand of a man suffering from tetanus was still virulent 

 at the end of^two years and a half. Soil impregnated with 

 spores, kept in a dififused light, was shown to be very viru- 

 lent after several months. Putrefaction does not alter 

 the spores. 



HABITAT OF THE BACILLUS.— Nicolaier's bacillus 

 is very widely disseminated. It is found in the soil. It 

 was in earth that Nicolaier discovered it. It exists in the 

 dust of streets and dwellings, in cultivated fields and on 

 the surface of vegetables. The dust of hay is tetanic. 



The spores are much more abundant at the surface of 

 the earth than underneath it. Below the depth of a milli- 



