THE PRESIDENTIAL ADDRESS. 15 
Metchnikoff studied the question in a remote part of Siberia where the 
tubercle bacillus was unknown. He states that very many of the young 
men and women who migrated from this clean country into the big cities 
died of acute and rapid tuberculosis, on account of not having been exposed 
to infection in their childhood. 
The experience of Colonial troops in the late war is instructive. Thus, 
in France the Senegalese, who are almost without tuberculosis in their 
native condition, and were found to be free from tuberculosis on reaching 
France, developed in large numbers an acute and fatal form of tuberculosis 
in spite of the hygienic measures enforced by the Army authorities. 
This raises a curious point. If it were possible for any country to clear 
itself of the tubercle bacillus, it would appear to be incurring a great risk 
for an inhabitant to migrate into any neighbouring country. 
But, in spite of this, it is the duty of medical men to keep in check, as 
far as possible, the ravages of the disease. 
The preventive measures against tuberculosis at the present time are, 
in the first place, improvement in the general hygienic conditions. Thereby 
individual resistance—and communal resistance—can be remarkably 
increased. 
In the second place, as every case of tuberculosis must arise from a 
previous case, either human or bovine, it is very necessary that methods 
of early diagnosis, preventive treatment, and segregation of the more 
infective types should be employed. This is done by the setting up of tuber- 
culosis dispensaries, care committees, sanatoria, hospitals and colonies. 
These several elements are combined in the model Tuberculosis Scheme 
which is now universal throughout Great Britain. 
In the third place, much can be done to anticipate and limit the 
progress of infection by the use of tuberculin, but caution is required 
in assessing the claims, sometimes hasty and extravagant, advanced by 
adventurers in this field of research. 
Many other points might be brought forward, but the subject is such 
a vast one that I must content myself with drawing attention to the 
importance of a sound milk supply. 
The contamination of our home herds with tuberculosis is so great 
that no pains should be spared to secure a safe milk supply, and I under- 
stand that the city of Toronto is a model in this respect. 
The result of these methods of prevention against tuberculosis may be 
given briefly. Sir Robert Philip writes that in Scotland ten years before 
Koch’s discovery the death-rate from this disease was 404 per 100,000; 
