496 Veterinary Obstetrics 



which have not been previously used. In those sections of the 

 country where beef breeding is the principal industry, it is found 

 that a large proportion of the outbreaks of contagious abortion 

 occur in those herds where pedigreed stock is bred and where 

 there is frequent interchange with other breeders or the animals 

 are habitually exhibited at agricultural fairs, where they become 

 exposed to the malady. 



Etiology. The bacteriology of infectious abortion of cows has ( 

 not been fully determined, and the findings of different investi- 

 gators are very contradictory. Bang, and those in accord with 

 him agree that the malady is due to a short bacillus. This is a 

 non-motile organism which contains no spores but, when arti- 

 ficially cultivated, frequently shows, at one end, a spherical en- 

 largement. The micro-organism is easily stained with analine 

 dyes, either aqueous or carbolized. It does not color by the 

 Gram method. It may be artificially grown in an atmosphere of 

 oxygen or in the almost complete absence of oxygen, but does not 

 grow rapidly in ordinary air. It may be grown on gelatine, agar 

 and various other media. In these media it grows in clumps the 

 size of a pin-head, which are conical in form and have very definite 

 outlines and, in transmitted light, have a bluish color. The 

 bacillus perishes in these artificial cultures in about two weeks 

 and is readily destroyed by heat and disinfectants. It is claimed, 

 however, that they may continue to exist in the secretions of 

 the uterus for month after month. According to experiments 

 recorded by Bang (Jour, of Comp. Path, and Therap., Vol. 19, 

 page 191) the injections of pure cultures of this organism into the 

 vaginae of pregnant cows and sheep caused abortion or premature 

 birth in 8 to 10 weeks, in which cases the micro-organism was 

 obtained in pure cultures from the vaginal discharges, as well as 

 from the exudate upon the surface of the cotyledons and the 

 chorion. 



Bang also injected abortion bacilli into the jugular vein and, 

 in case of two pregnant ewes, living lambs were produced. The 

 specific abortion bacilli were found in the chorion. The same 

 experiment was tried upon a pregnant mare, which gave birth 

 after 27 days to a very small foal which died a day later. Here 

 again he found, upon the chorion, bacilli which could not be 

 differentiated from tho.se which had been injected into the vein. 



Bang injected a pure culture of the micro-organism into the 



