PRINCIPLES OF VETERINARY SURGERY 439 



mode of development of tetanus under many circumstances. 

 They cast a vivid light upon the etiology of tetanus, and 

 show all of its factors. The spores existing everywhere in 

 nature are frequently inoculated, but pure. Tetanus re- 

 quires the foreign body that carries also pyogenic micro- 

 organisms into the wounds. The traumatism plays the 

 part of lactic acid. It is thus that contused wounds soiled 

 with earth or dung are most liable to be followed with 

 tetanus. 



Dung contains many spores. The bacillus of Nicolaier 

 finds in the intestines, the conditions favorable to anaerobic 

 life, and multiplies. In spite of the wide dififusion of the 

 tetanus germ in the soil, in the dust of dwellings, dung- 

 piles, stable-floors, etc., and in spite of the numerous cir- 

 cumstances which favor the contamination of wounds by 

 these germs, tetanus is comparatively rare. According to 

 the statistics of Hering there might be one case of tetanus 

 among three thousand patients. This comparative rarity 

 of tetanus is due to the fact that the bacillus of Nico- 

 laier cannot exert its pathogenic action except in special 

 complex, multiplied conditions that are not often com- 

 bined. Viallard, Rouget and Vincent have experimentally 

 determined the combination of conditions required for the 

 propagation of tetanus spores in a nervous organism. They 

 have shown that tetanus spores exist in nature in a different 

 form from that observed in the laboratory. Instead of being 

 impregnated with toxins, like the laboratory cultures, they 

 are destitute of them. When introduced into the tissues 

 they must first propagate before secreting the poison that 

 produces the disease In order to study how the spores act 

 on the living organism, under natural conditions, it is neces- 

 sary to operate with spores deprived of their toxins. 



ETIOLOGY. — Tetanus is always due to the introduction 

 of the bacillus of Nicolaier into the body. Spontaneous teta- 



