Sterility 197 
cases it may be necessary to make a small incision 
in order to dilate the opening. It is probable that 
mechanical manipulation of the parts, aside from the 
mere dilation of the passage, is conducive to fertili- 
zation, by increasing the blood supply to the part. 
There are some mechanical contrivances, now on the 
market, which are useful in dilating the mouth of the 
womb, and increasing the probability of pregnancy, 
especially in mares. 
A simple treatment that is known as the “yeast 
treatment” gives good results in some cows that fail to 
breed. Take a cake of compressed yeast and mix with a 
pint of boiled warm water and allow to stand in a warm 
place for twelve hours. When ready to use, add another 
pint of warm water. This yeast mixture should be 
injected, as far as possible, into the vagina of a cow at 
the first signs of heat, and the cow bred as she is going 
out of heat. 
Females that have aborted are not so likely to 
breed, especially when the abortion has been due to 
contagion. Tumors, malformations, or diseased con- 
ditions of the genital organs in females, are frequent 
causes of sterility. In mares that have been bred, 
there is sometimes an opening from the vagina into 
the rectum, through which pieces of dung often pass 
and escape from the vulva. This opening usually 
results from injury to the part while foaling. Such 
mares do not breed readily and are liable to injury 
in foaling afterward. In many cases this opening 
between the rectum and the vagina can be closed by a 
‘good surgeon and the mare hecomes as valuable as ever 
