22 BULLETIN 106, U. S. DEPARTMENT OF AGRICULTURE. 
percentage of the cows and heifers have the disease of a severe type — 
when the nodules are very numerous, the vulvar mucosa deeply 
injected, red, inflamed and bleeding upon slight provocation, when 
there is an abundant muco-purulent vulvar discharge, when the 
vulvar lips are swollen and the malady takes on what some term the 
acute type — abortion is usually common and serious. When the 
disease is mild, or as some say chronic, or others cured, leaving 
behind, however, some clearly recognizable nodules, abortion occurs 
rarely. 
A still more significant clinical evidence that the granular venereal 
disease has an important relation to abortion is that abortion occurs 
at that age of the animal when the granular venereal disease is most 
intense; that is, in cows not over 4 years old. Usually it is during 
the first or second pregnancy that cattle abort when the granular 
venereal disease is at its zenith. 
The granular venereal disease is also claimed to be the essential 
cause of sterility in cows. A great variety of diseases may bring 
about sterility, as, for example, tuberculosis of the genital organs, but 
they constitute a very small minority of cases. The vast majority of 
cases of sterility are due, according to our observations, to one 
widespread infection, inseparable from contagious abortion. In the 
experience of the writer, fully 98 per cent of the sterility of cattle 
must be regarded as identical in etiology with abortion. In one case 
the infection prevents conception; in another it attacks the embryo 
or fetus to cause its death and expulsion, or its expulsion from the 
uterus in an immature though living state (premature birth), or its 
birth in a more or less normal state, at full term, the infection existing 
in the uterus causing metritis with or without retained placenta. 
Sterility and contagious abortion are in effect comparative terms, 
without any clear line of demarcation between the two phenomena. 
THE GRAVID UTERUS OF THE COW. 
The uterus is a branched, hollow organ, divided into a cervix, a 
body, and two horns. 
The cervix uteri is of great interest in the consideration of some of 
the phenomena of contagious abortion, as well as of sterility. In the 
nonpregnant animal it is 3 to 6 inches long and 1 to 3 inches or more 
in diameter. Its walls are thick, dense, and resistant. The cervical 
canal is a narrow, tortuous channel, affording an avenue of communi- 
cation between the vaginal and uterine cavities. In the healthy non- 
pregnant cow, when not in estrum, the mucosa of the cervical canal 
is elaborately folded longitudinally. The folds are in immediate 
contact at every point, completely occupying the space of the channel, 
the contact of the mucous folds being rendered close and firm by 
