FERTILITY 617 



membrane of the uterus, and more particularly around the 

 cotyledons, but the afEected area may be considerably greater. ' 

 The chief mode of entrance is the vagina (especially during 

 copulation, when the contagion is introduced by the buU's penis^), 

 but Bang has shown experimentally that the germs may be 

 carried to the seat of the disease by the blood after intravascular 

 injection, and furthermore that they can be absorbed through 

 the alimentary canal. Thus, after administering some bouillon 

 culture to a cow, the placenta was found covered with typical 

 exudate rich in bacilli. There is some experimental evidence 

 that cows may acquire immunity to the disease, at least tempo- 

 rarily. Investigations show also that mares, sheep, goats, dogs, 

 and guinea-pigs may be infected with the bacillus experimentally, 

 but in all probabihty the disease is ordinarily confined to cattle. 

 The abortion microbe is stated to be oval or rod-shaped, between 

 one and two microns in length, and non-motile. It sometimes 

 occurs singly, but in many places the bacilh are collected in dense 

 groups or colonies. The microbe associated with atortion out- 

 breaks in sheep is said to be a vibrio and therefore totally different. 

 It has been isolated and used experimentally to infect pregnant 

 ewes. Pregnant cows, however, cannot be infected by it. 



The external use of antiseptics is said to prevent the 

 spread of contagious abortion by means of disinfection, and 

 this is the treatment prescribed by the Board of Agriculture.^ 



The causes of abortion in sheep are dealt with at some length 

 by Heape in the paper already referred to.* Statistical evidence 

 shows that an excessive proportion of shearUng ewes in a flock 

 is associated with a relatively high percentage of abortion, and 

 that ewes of particxilar breeds in certain districts, or run on 

 certain subsoils, are more Hable to abortion than the average 

 for the breed in question. Thus Lincoln sheep run on the Wolds 

 suffer much more from abortion than sheep of the same breed 

 in other districts. The Southdown and Hampshire Down 



' Report of the Departmental Committee appointed by the Board of 

 Agriculture and Fisheries to inquire into Epizootic Abortion, London, 1909. 



' According to the Report referred to above, nothing more than a quite 

 subsidiary rdle in the spread of the disease can now be referred to the bull. 



' Board of Agriculture Leaflet, No. 108, 1904. 



' Heape, "Abortion, Barrenness, and Fertility in Sheep," Jour. Royal 

 Agric. Soc, vol. x., 1899. 



