Microhic J)iseases Individually Considered. 213 



from three to eiglit days according to the dose in- 

 oculated ; the lungs are gorged with blood, the intes- 

 tines are frequently the seat of a violent inflammation 

 with resulting diarrhoea ; the spleen is tumefied and, 

 alonff with the liver, often shows white necrosed foci. 

 At the place of inoculation a creamy mass is found, 

 also the product of a coagulative necrosis. 



The guinea jng dies in the same time, and with the 

 same lesions, as the rabbit.* 



The pigeon is very resistant to pneumo-enteritis. It 

 withstands small doses inoculated in the pectoral 

 muscle although the inoculated point becomes the seat 

 of a sequestrum similar to that produced by chicken 

 cholera. Very large doses kill it in less than two 

 days. 



The chicken is refractory. 



The pig is difficult to contaminate by hypodermic 

 injection ; on the other hand, it succumbs ninety times 

 out of a hundred to ingestion of virulent products. 

 It contracts the same disease by inhalation of dust 

 containing virulent matters held in suspension in the 

 air, and also by intra-vascular injection. 



Etiology and pathogeny. — The cause of pneumo-en- 

 teritis resides in the bacillus discovered by Salmon ; 

 the disease generally shows itself on a farm in conse- 

 quence of the introduction of an infected hog ; it is 

 transmitted from one hog to another by the ingestion 

 of food or drink soiled by the intestinal dejections 

 and nasal discharge of the diseased animals. 



* [The guinea pig appears to be somewhat less susceptible than 

 the rabbit, and rarely shows the characteristic necrotic foci found 

 in the liver in the latter animal. — D.] 



