CHAPTER III 



Natural immunity. — Noxious subjects and 

 harmless subjects.— Influence of 

 the system of breeding. — Vallee, 

 Friedberger and Fronhern. 



Some subjects are harmless. Among 

 the noxious subjects some are more and 

 others less contaminating. Serous tuber- 

 culosis is not contaminating, nor is that 

 wich does not manifest itself with viru- 

 lent excretions . 



In presence of a noxious subject, va- 

 rious circumstances whic tend to pre- 

 vent contagion may be enumerated; in 

 the country, under the wide-spread sys- 

 tem of breeding cattle, in use in the Ar- 

 gentine, an animal attacked by tubercu- 

 losis is almost harmless, in spite of its 

 virulent excretions . The bacillus of Kock 

 is amply spread about the surroundings, 



