VETERINAEY MEDICINE. 585 



insidious ways in wbicli aljortion may be spread, for it is impossible for the 

 ordinary individual to say whether a pregnant animal is affected or not. . . . 

 Cows which have aborted must be considered sources of infection so long as 

 the discharge continues to come from the genital organs, and it may continue 

 intermittently for a few weeks if the animals be not treated. Such animals, 

 if not isolated, may continue to infect the" sheds, or the pastures when turned 

 out to graze. . . . The most certain method of infecting an animal with abor- 

 tion is to inject natural virulent material or active cultures into the blood 

 stream." In experiments this method of infection gave positive results in 8 

 cases and failed in none. 



"Animals can also be infected by the subcutaneous inoculation of considerable 

 quantities of virulent material. . . . Out of 5 attempts to experimentally infect 

 animals by this method 3 were positive, and 2 were negative. We consider 

 that this method of infection must be looked upon as an artificial one, and we 

 do not think it probable that under natural conditions animals are at all likely 

 to be infected by virulent material gaining access to a wound." By introducing 

 virulent material per vagiuum 5 positive and 3 negative results were 

 obtained. In ingestion experiments "3 positive results were obtained against 

 1 negative. We do not think it would be warrantable on this comparatively 

 small number of experiments alone to conclude that infection is more likely to 

 follow when virulent material is swallowed than when it is introduced by the 

 vagina." , . . The authors, however, are inclined to believe that the disease is 

 more frequently contracted by ingestion than in any other way. " Presumably, 

 the bacilli are absorbed from the intestine and gain the blood stream, whereby 

 they reach the uterus. ... In the experimental attempts to infect with natural 

 virus by way of the vagina, 3 were followed by positive results and 3 by nega- 

 tive, in spite of the fact that the material was deposited in enormous quantity 

 right on and around the os uteri by means of a long tube." 



The symptoms are briefly considered. Under the headings of distribution 

 and identity of the disease it is stated that the disease is very prevalent through- 

 out Great Britain. "Abortion Vv'as experimentally induced by introducing the 

 microbe of cattle abortion into the bodies of cows, ewes, goats, bitches, and 

 guinea pigs. . . . We are of the opinion that bovine abortion ... is essentially 

 a disease of cattle, and although other species can be experimentally infected 

 in the laboratory they are not likely to contract the disease in practice except 

 as the result of gross carelessness in the disposal of infected material. . . . 



" It is an easy matter to identify the characteristic clumps of abortion bacilli 

 in microscopical preparations made from the uterine exudate discharged imme- 

 diately before and after abortion. . . . No evidence has been obtained during 

 the investigation to show that natural immunity to the abortion bacillus is 

 possessed by any individuals of the bovine species. . . . From general inquiry, 

 we are inclined to believe that a majority at least acquire a serviceable degree 

 of immunity as the result of an attack, but there is no doubt that in practice 

 a considerable proportion abort twice and a small number abort even three 

 times. . . . From the first it appeared that the disease was not one against 

 which a protective serum could be successfully used. The protection derivable 

 even from a potent serum can not be depended upon to last more than 2 or 3 

 weeks. . . . Moreover, as curative agents in advanced stages of disease, sera, 

 as a rule, have little or no value." 



An experimental test of carbolic acid administered internally gave negative 

 results. Treatment with dead bacilli appears to have failed in 1 case and to 

 have succeeded in 2. It appears that the methods which have been relied upon 

 in the past for the prevention of abortion and its eradication from a herd have 

 jiot brought about any material improvement in the general condition of the ' 



