Contagious Pneumonia in the Horse. 131 



receptive to this resting germ, until under some special devital- 

 izing influence, like exposure, exhaustion or local disease, it 

 finds its opportunity and the weakened system succumbs. Then, 

 acquiring new force through its life in the debilitated system, it 

 starts on a recrudescence, and an epizootic is mistakenly supposed 

 to have started without a preexisting microbian cause. 



Cadeac even advocates the theory that the same germ possessed 

 of greater or lesser virulence, is always present in ordinary 

 stables and horses, and habitually causes in exposed or debili- 

 t ated animals an ordinary fibrinous pneumonia with no perceptible 

 tendency to transmission by contagion ; that, in other cases 

 when a considerable number of horses have their defensive 

 powers impaired, it gains a wide extension ; and, that in some 

 such cases, the germ that has been living as a comparatively 

 harmless saprophyte, suddenly acquires an unwonted potency, 

 and breaking down the barrier of partial immunity, attacks exposed 

 animals on a large scale and irrespective of weather perturbations, 

 or debilitated conditions. He quotes from Trasbot instances that 

 seem to support this hypothesis, which is not at all in disaccord 

 with the habits of bacterial life, yet we require a solid basis in 

 bacteriological experiment to make it unassailable. 



Bacteriology. Siedamgrotzky (1882) found in the hasmorrhagic 

 centres in the affected lung and in the pleural exudate micrococci. 

 DieckerhofE (1882) and Mendelsohn (1883) found in the pleural 

 exudate streptococci. Chain cocci were also found by Peterlein 

 (1884), Perroncito (1885), Delamotte and Chantemesse (1888), 

 and Mosselman and Lienaux (1893). 



Schiitz (1887) found a diplococcus which he studied very fully 

 and this is corroborated by lyUStig's ovoid bacterium, by Cadeac's 

 micrococcus and diplococcus. In Dr. V. A. Moore's cultures, at 

 the N. Y. S. Veterinary College, cocci were found constantly in 

 pure culture, sometimes as a diplococcus, but under slightly al- 

 tered conditions the streptococcus form predominated. As the 

 difference between two, and three or more cocci in chain form is 

 merely a question of early or late separation of cocci which mul- 

 tiply in line, the apparent discrepancies in the above observations 

 do not imply any real difference in the microbe. 



Inoculated in pure cultures the Schiitz diplococcus killed mice 

 in 24 to 48 hours with enhanced virulence of the germ. In the 



