ETIOLOGY 39 



They are supposed not to be able to live longer than six weeks 

 within the animal body ; but in certain cases, especially in en- 

 cysted deposits in the lungs, the virus may remain active for a 

 much longer time. 



Baumgarten and Hell oppose the view that Schiitz's strep- 

 tococcus is specific, while Rust aud Fiedler support it. Hell 

 maintains that with our present means of investigation, the 

 bacteria of contagious pleuro-pneumonia cannot be differen- 

 tiated from the pyogenic streptococci or from the strepto- 

 coccus of erysipelas. In fact, Hell believes that the strepto- 

 coccus of Schiitz has a pathogenic effect in horses affected 

 with pleuro-pneumonia; but as there is no positive proof of 

 its being specific, he maintains that we are justified in sup- 

 posing that this ubiquitous micro-organism has only an injuri- 

 ous influence on the course of the disease, contributing to the 

 production of the secondary lesions. Hell further states that 

 protective inoculation with Schiitz's bacteria, which at first 

 promised good results, has not proven to be satisfactory. 

 Fiedler, on the other hand, has obtained the same bacteriolo- 

 gical results and has arrived at the same conclusions as Schiitz. 

 He also states that he has experimentally produced pleuro- 

 pneumonia in a horse by inoculation of cultivations of these 

 bacteria. 



Lignieres (See § 24) believes that his cocco-bacillus 

 stands in an etiological relation to this disease and that here 

 as in strangles the streptococcus is a secondar}' invader. 



The writer made a bacteriological examination of the 

 organs from five cases of fatal contagious pneumonia of the 

 horse. In each case, the lungs were more or less hepatized, 

 but the other organs were nearly normal in appearance. 

 Without exception, a streptococcus appeared, usually in pure 

 culture, from the lungs. The inoculated media from the other 

 organs, liver, spleen, and kidney remained clear. The strep- 

 tococci isolated from the different cases were identical in their 

 morphology and cultural manifestations and pathogenesis. 

 A microscopic study of the lungs from the different horses 

 showed micrococci singly, in pairs and occasionally in short 

 chains. Distinct capsules were not observed. In bouillon 



