32 HOG CHOLERA 



which are chapped or wounded as a result of nurs- 

 ing litters. We know less regarding the primary 

 cause of necrotic lesions that appear in the 

 lungs. 



It is still an open question whether B. necropho- 

 rus is really capable of penetrating normal mu- 

 cous membrane and producing its characteristic 

 effects, but usually it does not. Likewise there is 

 doubt as to whether it releases a toxin, the prob- 

 ability being that at times it does, for especially in 

 young pigs suffering with necrotic stomatitis, 

 death often takes place suddenly, before it can be 

 explained on the basis of the existing local lesion. 

 On the other hand, some pigs will harbor surpris- 

 ingly extensive lesions without marked systemic 

 disturbances. Some regard B. necrophorus as a 

 secondary invader that may cause the "button 

 ulcers " which appear in chronic hog cholera, but 

 there is at least a distinct difference between the 

 button ulcer in which degenerative and regenera- 

 tive processes coexist, and the usual lesion pro- 

 duced by B. necrophorus, in which a progressive 

 necrosis prevails as long as the exciting cause re- 

 mains active. There is also somewhat meager 

 evidence that the organism may in rare instances 

 cause petechial hemorrhages in the serous mem- 

 branes and kidneys. 



Bact. suisepticum, B. suipestifer, B. pyocya- 

 neus, and Bact. necrophorus have two characteris- 



