ABORTION 121 



closely. The bacilli do not grow in ordinary agar or gelatin agar, develop 

 poorly in bouillon with glycerine, better in bouillon glycerine mixed with 

 serum. They grow best in gelatin-agar-serum (that is, two parts gelatin 

 mixed with one part serum). A culture raised in this medium in a high 

 glass (Liborius) has the peculiarity, that its small colonies only develop in 

 a certain zone, that is, a little below the surface. Therefore, it developes 

 in the zone of aerobic organisms, but not on the surface. 



Strange to say, it develops on the surface when pure oxygen is 

 allowed to flow over the congealed liquid, after which the glass is sealed 

 with paraffin. This characteristic, of course, is of great assistance in 

 identifying the bacillus. 



The introduction of a pure culture into the vagina of a pregnant cow 

 produces abortion in 10 weeks; the same pathological changes are then 

 found as in the spontaneous cases of enzootic abortion. In two experi- 

 mental cows Prof. Bang introduced cultures twice during the period of 

 incubation; thus it is possible that the time is less than ten weeks; he pre- 

 sumes, however, that this time is correct and that the first inoculation was 

 the effective one. 



In the foetal envelopes a considerable gelatinous oedema is constant 

 between chorion and allantois. 



In practice, we can readily recognize enzootic abortion by this 

 peculiar advance and the immediately following dirty but inodorous 

 discharge. 



The intestinal tract of the foetus at times contains the pure culture of 

 the same bacillus. The organisms are very resistant and remain alive for 

 seven to ten months when kept in a refrigerator. 



Eradication. — 1. Immediate removal of the pregnant cow from the 

 stable, as soon as she offers premonitory symptoms of abortion, to prevent 

 discharge of the infected material into the stable ; destruction of the 

 afterbirth, disinfection of the uterus, etc. 



2. A special bull must be used for the cows which aborted, as the bull 

 no doubt is often the intermediary of the contagion. ' 



Symptoms. — When infectious abortion has repeatedly 

 happened in a stable, or has returned year after year, the pre- 

 monitory indications of an early expulsion are noticed at an 

 early period. The first changes are in the composition of the 

 milk, which resembles colostrum. When abortion occurs in 

 the seventh month and the animal is dry, approaching abortion 

 is usually not so quickly perceived ; an observing attendant 

 recognizes it by the swelling of the udder. At the same time 

 a reddish or brownish-red vaginal discharge is seen ; sometimes 

 it is more purulent or dirty white. The vulva is slightly tume- 

 fied, the ligaments sunk in a little. Many observers noticed a 



