535 
bacilli, and such pure cultures were proven to be virulent for cattle. 
In one instance, a cow inoculated subcutaneously with a culture of 
this kind became affected with rapidly progressive, generalized tuber- 
culosis, which terminated in death after a few months. 
Fifth. Hogs fed with the feces of tuberculous cows contracted 
typical tuberculosis. The feces were collected under conditions which 
insure that no infectious material was introduced into them that did 
not pass from the bowels of the cows. 
The expulsion of tubercle bacilli by cattle per rectum with their 
feces is one of the most important causes of tuberculosis among hogs, 
as we may judge from the following illustration, which represents a 
common farm scene — a herd of hogs in a hog yard adjacent to a cow 
stable. The cow stable contains a herd of tuberculous cattle ; the cat- 
tle are not permitted to enter the hog yard and the hogs are not per- 
mitted to enter the cow stable or the field in which the cows pasture. 
More than half the hogs that remain in the hog yard and root in the 
manure pile contract tuberculosis within' six months. 
The relative frequency with which tuberculous cows expel tubercle 
bacilli per rectum has not been accurately determined. Among 12 
cows, collected' from several dairy herds for use in an investigation 
in which a number of apparently healthy tuberculous cows were 
required, five, or 41f per cent, were found to be passing tubercle 
bacilli^ intermittently, per rectum with their feces. Eighteen months 
later the number had increased to ten, or 83J per cent ; that is, it had 
doubled, though the majority of the cows still retained their ap- 
parently good condition and showed no marked symptoms of tuber- 
culosis. The feces of only a small number of cows that had been 
affected with tuberculosis three years or more have been examined ; 
they were all found to be passing tubercle bacilli per rectum. 
THE APPEARANCE OF CATTLE THAT EXPEL TUBERCLE BACILLI. 
When we think of animals afflicted with diseases we usually picture 
them to our minds as showing distinct variations in their appearance 
and demeanor from what we regard as healthy and normal. Disease 
and no symptoms is almost a contradiction, and this seeming contra- 
diction and truly paradoxical condition is one of the important facts 
about tuberculous cattle. 
As no description can define the appearance of an animal as well 
as a photograph, the following illustrations, Nos. IT to 26, inclusive, 
made from photographs, are presented to show the frequently ex- 
cellent, seemingly healthy condition of dangerously tuberculous cat- 
tle. It must be added that the cattle represented in the pictures do 
not cough ; they have excellent appetites and no visible and no audible 
respiratory difficulties; in all respects they act like healthy animals 
