NINTH ANNUAL YEAR BOOK— PART VI 237 
Now, that hog came from one of the best breeders of that particular 
breed in the middle west, but I understand that it has been the practice 
of that man to feed his hogs on milk which was evidently tubercular. 
From that you will see that you can go right back and follow along un- 
til you get to the point where the animal contracted the tuberculosis. 
That brings up another phase of the subject, the method of transmission, 
and that has been worked out within the last few years and become 
more generally considered. Nearly all tuberculosis is ingestive tu- 
berculosis, or tuberculosis transmitted, where the infection takes place 
through the feed or the animals live together. That has become the ac- 
cepted theory. Infection may take place through the milk pail, the 
separtor milk, cream or anything from the dairy. 
What I want to get at in a short time is the manner of infection 
and what you must do to prevent it. There is no question but what 
tuberculosis is transmitted through milk. There is no question but 
what milk becomes infected either through a diseased condition of 
the cow or through the contamination of the milk from some of the 
discharges from the cow. Reynolds, of Minnesota, and Mohler and Cotton 
experimenting at the U. S. Experiment Station at Washington, have demon- 
strated this and we simply discard the fact that it is transmitted through 
the air. You can see there is a relation between tuberculosis in cat- 
tle and in hogs. To further demonstrate these points, after making the 
test of some cattle at the college farm we isolated the tubercular co',vs 
and placed in that feed lot some thirty head of hogs. Two died from 
ofher causes and there were left twenty-eight head. They ran after the 
cattle right out in the open. The cattle were fed on the ground and 
the twenty-eight head of hogs followed the cattle and slept with them 
I presume in the pen and at the end of one hundred days these hogs 
were taken to Chicago market and killed and twenty-two out of the 
twenty-eight, or about eighty per cent, were tubercular. Those animals 
simply ran after the cattle, picked up the offal, and that is the only 
way we have of figuring out how they became infected. We bought 
them from different farmers and killed enough to check the bunch. 
A little later, some four or five weeks ago, we shipped twenty five head 
to the Agar packing plant. They were around about a year old and had 
been running around the farm after the cattle. Out of the twenty-five 
head ten were tubercular, or forty per cent. Now, they probably had 
some milk, possibly from some of these cows before they were tested, 
or from a dairy or creamery and had become infected that way, but we 
do know that the twenty-two out of the twenty-eight became infected 
from rooting in the droppings from the cows. That may not occur with 
all tubercular cattle, but it occurs in cattle that have what we call 
open tuperculosis, where they will drop tupercular germs along with the 
droppings. The cow may expectorate this material or cough it up as 
far as the larynx. Then she swallows it and it is taken up and distributed 
to the different parts of the body. Any cow may be in a condition where 
she has open tuberculosis and still be fat enough for market so that 
we cannot tell by examining the cow whether she is tubercular or not. 
This problem will have to be dealt with. The packers have tried to get 
at it but they have failed. At the present time there are a great many 
