DESCRIPTIONS OF PATHOGENIC BACTERIA. 163 



the bacteria produce phlegmonous erysipela- 

 tous processes in the skin and pneumonitic 

 processes in the lungs, but in the intestine 

 marked changes are very seldom brought 

 about. Spreading from the place of inocula- 

 tion a general infection in the form of septicae- 

 mia results. If fowls are fed with pure cul- 

 tures an enteritis is set up, and if the animals 

 be injected intramuscularly a coagulation 

 necrosis of the muscular tissue is caused ; a 

 general infection often concludes both pro- 

 cesses. In slightly susceptible animals only 

 local abscesses and necroses occur. If the 

 bacillus is in a condition adapted for growth 

 in the body of mammals it is relatively more 

 virulent towards them than towards fowls ; if 

 it is adapted for an existence in birds the re- 

 verse is true. Because of the discovery of 

 these two extremes it has been thought that 

 two varieties exist, mammalian septicaemia 

 and avian septicaemia, which however, pass 

 over into one another. Such fluctuations in 

 virulence in a state of nature have given rise 

 to variations in the statements of authors re- 

 garding these diseases.' The fact that epi- 

 demics are more often observed among swine 

 than among cattle is due to the differences in 

 stabling and feeding, swine being more exposed 

 to danger, than the latter. Where wild swine 



