1 Mar., 1899.] QUEENSLAND AGRICULTURAL JOURNAL. 218 
-cause of the disease or even the predisosition to it would gradually dwindle 
-away into insignificance. In Denmark, Professor Bang has shown that by 
exercising a little.care, and the free application of tuberculin, how comparatively 
easy it is to protect cattle from infection, and how a healthy herd may be bred 
from a severely infected one. 
As evidence of this, Nocard says:—‘“‘I had occasion to test with tuber- 
-culin all the animals on a large and fine farm in the north of France; 55 out 
of 105 were tuberculous—46 out of 57 adults; 9 out of 42 aged from four 
months to two years. ‘Twenty months later I repeated the test on 30 of the 
young animals which had escaped infection, and on 14 more which had been 
born since the first trial Of this number 25 were born of tuberculous 
mothers. Not one of these animals gave the slightest reaction—not one had 
become tuberculous; and most of them are now two, two and a-half, three, and 
more years old.” 
After the first trial all the healthy animals were strictly isolated from the 
affected ones. 
Methods of Detecting Puberculosis—Comparative pathologists are agreed 
that there are several diseases which may simulate and be mistaken for bovine 
tuberculosis. ‘Therefore on all occasions, when possible, the clinical diagnosis 
ought to be controlled by bacteriological examination of the suspected products 
—pus, discharge from the nostrils, expectoration, glandular pulp, milk, &e. 
Tf Koch’s bacillus is found, with all its well-defined and peculiar histo-chemical 
characters, the existence of tuberculosis may be affirmed. If the search for 
tubercle bavilli does not give positive results, as is often the case in cattle, 
experimental diagnosis is proceeded with. This is done by injecting some of 
the suspected products directly into the peritoneal cavity of one or more 
guinea-pigs, which are extremely susceptible to tuberculosis. Should the 
inoculated material be tuberculous, its virulence will be proven by the progress 
of the disease, the first symptoms usually appearing in from twenty-five to 
thirty days, when the animal may be killed and examined. On post-mortem, 
the lympathic glands and spleen will be seen to be considerably enlarged and 
crowded with tubercular nodules, while the liver and lungs will be less severely 
attacked. If these appearances are confirmed by microscopical examination, 
the diagnosis is thus made complete. 
The two methods just described are, of course, inapplicable when tubercu- 
losis in the suspected animal is confined to the abdominal organs, to serous 
membranes, or to glands of cavities; consequently they are impracticable for 
general use. But, thanks to the researches of Koch, we have in the agent 
known as tuberculin a most perfect test for tuberculosis. Experiments made 
by thousands in all countries have shown that Koch’s tuberculin, injected in, 
small doses under the skin of suspected cattle, sets up in tuberculous animals 
alone an intense febrile reaction, permitting one to assert the existence of 
lesions so minute that all other methods of diagnosis, bacteriological and 
clinical, would be powerless to reveal their presence, or even to make one 
suspect their existence—in fact, it becomes so near being an infallible test that 
the errors of diagnosis, based on its constant use, are practically z7/. ; 
It may be asked, What is tuberculin, and how is it applied? Tuberculin 
is a simple glycerine extract of the toxie products of a broth culture of the 
tubercle bacillus; but its preparation, although not at all difficult, requires 
very special care. 
A culture of tubercle bacilli in glycerine nutrient medium of special 
formula, after five or six weeks in the incubator at a uniform temperature of 
37 decrees Centigrade, is sterilised in an autoclave at 110 degrees Centigrade ; 
it is then concentrated in vacuo in the presence of sulpburic acid till the bulk 
of the culture *s reduced to a tenth part of the original quantity, then passed 
through a specially designed Pasteur-Chamberland porcelain filter under an air 
pressure of about 4.00 lb. on the square inch, which strains all the remains of 
the dead bacilli from the liquid, and afterwards kept in well-stoppered bottles 
and protected from light and heat. As the original culture contained 5 per 
