436 PRINCIPLES OF VETERINARY SURGERY 



When a portion of tetagenic earth is inoculated into ani- 

 mals it always causes tetanus. If it is heated to a tempera- 

 ture that will destroy the other micro-organisms without 

 lessening the vitality of the tetanus spores, the earth loses 

 its virulence. But if the other microbian species are restored 

 to this same earth its virulence is likewise restored. If the 

 earth heated to 85 degrees ceases tO be virulent, it is not 

 the result of vitiation or destruction of the tetanus spores, 

 because the virulence can again be restored under certain 

 conditions. The explanation is found in the fact that the heat, 

 wliile respecting the specific germs, has eliminated the 

 greater part of the other micro-organisms and has sup- 

 pressed the pathogenic p.uperties ot those that have re- 

 sisted. The cultivation shows that the proportion of viable 

 germs is very small in this heated earth. It is incapable of 

 producing either a local lesion or tetanus, but if this inactive 

 earth is again supplied with the adventitious germs the origi- 

 nal virulence at once returns, hence the following conclusion: 

 In tetanus following an earth inoculation, the bacteria, other 

 than the specific germ, play an important role in tlie path- 

 ogenesis of the disease. These bacteria produce lesions in 

 which the tetanus spores may grow. Their co-operation 

 is indispensable and when they are not present the spores 

 do not germinate and tetanus is not produced. 



Among the bacteria that favor tetanic action, the bacil- 

 lus prodigiosus deserves notice. The mixture of T-15 of a 

 cubic centimeter of a culture containing spores without tox- 

 ins with 0.5 cubic centimeters of a culture of bacillus pro- 

 digiosus, one month old, inoculated into cavies, produces 

 tetanus in thirty-two hours that becomes general and proves 

 fatal fifty hours after inoculation. 



All micro-organisms do not facilitate the evolution of 

 tetanus spores to the same extent. The staphylococcus py- 

 ogenes aureus, the streptococcus, the bacillus subtilis and 



