12 THE PRESIDENTIAL ADDRESS. 
by large families, groups of lightless and unventilated houses in the older 
burghs, clotted masses of slums in the great cities—a terrible picture, the 
heritage of the age of ignorance, internal strife, and walled towns. 
The people of new countries should see to it, and doubtless will see to it, 
that these old evils are not perpetuated. 
As Sir Robert Philip, Professor of Tuberculosis in the University of 
Edinburgh, has eloquently said: ‘ Were it possible to begin afresh the 
scheme of civilised life, were it possible to undertake anew the creation of 
cities and the homes of our people, were it possible to place within the 
re-created dwellings an understanding race, de-tuberculisation might be 
quickly attained. What a magnificent opportunity for the builders of the 
new cities, the moulders of fresh civilisations, with the grand purpose of 
** No tuberculosis.”” The architect, the sanitarian, and the citizen would 
agree in insisting that physiological laws should be paramount, that there 
should be effective obedience to the larger demands of hygiene in the home, 
the school, the workshop, the meeting-place and the cow-shed. 
‘ Mankind was born into air and sunlight : these are his natural heritage. 
They are more—they are the irreducible conditions of life.’ ) 
In regard to the tubercle bacillus it is so widespread, so ubiquitous in 
civilised communities, passing from one infected host to infect another, 
that it would seem impossible under existing conditions to prevent its 
spread. At present it is taught, and on what seems good evidence, that the 
majority of the population of our crowded cities has at one time or another 
been attacked by this disease. But in every hundred men who die in 
England, only about ten die of tuberculosis, which shows that a large 
percentage of the population successfully resists the tubercle bacillus. 
When this occurs it means that the person attacked possessed powers 
of resistance which enabled him either to destroy the invading bacilli 
or to deal with them so as to render them harmless. 
A point of importance in this connection is that it has recently been 
demonstrated that the disease is usually acquired in childhood. The fact 
is of capital significance, for if the disease is recognised sufficiently early, 
and the child is placed under good hygienic conditions, there is a very good 
chance of effective resistance and immunity against a second attack being 
set up. 
The present evidence goes to show that the presence of latent tubercle 
prevents a second invasion. If further outbreaks take place, they would 
seem to be due to a flaring up of the old latent tubercle rather than to a 
fresh infection. 
