DISEASES OF THE GENERATIVE ORGANS. 169 



in the milk or cheese for generations and no return has been made 

 in food or manure purchased. Here is the craving of an imperative 

 need, and if it is not supplied the health of the cow suffers and the 

 life of the fetus may be sacrificed. 



Among other causes of abortion must be named the death or the 

 various illnesses of the fetus, which are about as numerous as those 

 of the adult ; the slipping of a young fetus through a loop in the 

 navel string so as to tie a knot which will tighten later and intemipt 

 the flow of blood with fatal effect, and the twisting of the navel 

 string by the turning of the fetus until little or no blood can flow 

 through the consorted cord. There is in addition a series of diseases 

 of the mucous membrane of the womb, and of the fetal membranes 

 (inflammation, effusion of blood, detachment of the membranes from 

 the womb, fatty or other degenerations, etc.), which interfere with 

 the supply of blood to the fetus or change its quality so that death 

 is the natural result, followed by abortion. 



CAUSE OF CONTAGIOUS ABORTION. 



While any one of the above conditions may concur with the con- 

 tagious principle in precipitating an epizootic of abortion, yet it is 

 only by reason of the contarjimn that the disease can be indefinitely 

 perpetuated and transferred from herd to herd. When an aborting 

 cow is placed in a herd that has hitherto been healthy and shortly 

 afterwards miscaiTiage becomes prevalent in that herd and continues 

 year after year, in spite of the fact that all the other conditions of life 

 in that herd remain the same as before, it is manifest that the result 

 is due to contagion. WTien a bull living in a healthy herd has been 

 allowed to serA^e an aborting cow, or a cow from an aborting herd, and 

 when the members of his own herd subsequently served by him abort 

 in considerable numbers, contagion may be safely inferred. Mere 

 living in the same pasture or building does not convey the infection. 

 Cows brought into the aborting herd in advanced pregnancy carry 

 their calves to the full time. But cows served by the infected bull, or 

 that have had the infection conveyed by the tongue or tail of other 

 animals, or by their own, or that have had the external genitals 

 brought in contact with wall, fence, iiibbing post, litter, or floor pre- 

 viously soiled by the infected animals. Avill be liable to suffer. The 

 Scottish abortion committee found that when healthy, pregnant cows 

 merely stood with or near aborting cows they escaped, but when a 

 piece of cotton wool lodged for 20 minutes in the vagina of the abort- 

 ing cow was afterwards inserted into the vagina of a healthy, preg- 

 nant cow or sheep these latter invariably aborted within a month. 

 So Roloff relfftes that in two large stables at Erfurt, without any 

 direct intercommunication, but filled with cows fed and managed in 

 precisely the same way, abortion prevailed for years in the one, while 



