18 BULLETIN 106, U. S. DEPARTMENT OF AGRICULTURE. 
If we study the gravid uterus of the cow (or other ruminant) 
critically, the provisions against accidental injury to the fetus im- 
presses the observer as one of the most perfect physiologic arrange- 
ments to be found in animal life. The fetus of the ruminant is elab- 
orately protected during intrauterine life. The pregnant uterus lies 
on a gently inclmed plane, the abdominal floor, partly suspended 
by the vagina and broad ligaments. The fetus gets its nutrient 
supply, not ordinarily from a diffuse placenta as in the mare, or 
zonular placenta as in carnivora, where violence may cause placen- 
tal detachment and entail fetal death, but instead procures its food 
supply through 100 or more cotyledons, complex multiple placentas, 
each usually having a distinct neck, thus leaving an empty space 
between the uterus and chorion, permitting a to-and-fro movement 
between the uterine walls and fetal sac in every direction. The 
fetal security is further insured by its floating free within one and 
partly within a second sac of fluid. 
As indicated by Table 2, the uteri of over 1,700 pregnant cows 
and heifers were inspected. Probably very few of them had been 
shipped less than 100 miles by railroad, many of them hundreds 
of miles. They had been driven some distance to a railway station, 
huddled into shipping pens, forced into cars, crowded and jammed, 
and not rarely got down and were trampled. At every turn oppor- 
tunity was offered for crowding and jamming. Finally they were 
goaded into the killing pens, felled with a hammer, and tumbled out 
on the floor. Certainly they had been subjected to the dangers 
of mechanical and fright abortion. Yet, in all these cases, no trace 
of injury to the fetus, fetal membranes, or uterus which might 
possibly have caused abortion had the animal been allowed to live 
were seen. While such evidence does not prove the impossibility 
of accidental abortion in cows, it does indicate that it is not, after 
all, very readily induced. 
In further search for lesions of accidental abortion in stock-yard 
cows, two animals were purchased which had aborted in the car or 
yards and another had expelled a live fetus prematurely. These were 
killed within a few hours after the occurrence. In none of the three 
was there a trace of mechanical injury, but lesions were found which 
are described elsewhere, showing conclusively that the abortion was 
due, not to mechanical injury, fright, or other accidental causes, 
but to an infection within the uterine cavity, the evidences of which 
could not have accumulated in a day or a week. 
All other post-mortem examinations upon recently aborted cows, 
so far as found recorded, have uniformly shown, beyond question, 
that infection, not accident, was the essential cause of the death and 
expulsion of the fetus. No case of alleged accidental abortion in 
