THE PRESIDENTIAL ADDRESS. 1] 
power of resistance ; in tetanus, by pouring in antitoxins, already prepared 
in the serum of another animal, in order that they may neutralise the toxins 
of the invading bacilli as soon as they are formed. 
Tuberculosis. 
There are other important bacterial diseases, however, which cannot 
be attacked so simply.. For example, there is tuberculosis, a disease distri- 
buted over the whole world and one of the greatest scourges of civilised 
communities. It isa disease which has been known from time immemorial, 
but it is only within our own time that the bacterial cause has been recog- 
nised. I can well remember a day in 1882 when I met a fellow-student who 
had just returned to Edinburgh from Germany. He told me that it had 
been recently discovered that the disease was really caused by a living 
germ, the tubercle bacillus. It was difficult at first to believe such a 
revolutionary idea, but such was the interest and excitement raised that 
many workers at once took up the study of the subject and in a short time 
the truth of Koch’s great discovery was fully proved. This was a magnifi- 
cent example of research work, most admirably, carefully, and completely 
carried out, and placed Koch at once in the front rank of scientific 
workers. 
Before Koch’s discovery a good deal had been done in the way of preven- 
tion. Before all things, this disease is a disease of environment. Its birth- 
place and home is the sunless, ill-ventilated, overcrowded room. The late 
Professor Edmund Parkes, Professor of Hygiene at the Army Medical 
School, reduced to a great extent the incidence of tuberculosis in the British 
Army by procuring for the soldier more floor-space and more air-space in 
his barracks. It is related of General von Moltke that when he heard of 
the death of Parkes he said that every regiment in Europe should parade 
on the day of his funeral and present arms in honour of one of the greatest 
friends the soldier ever had. 
The prevention of tuberculosis is thus seen to depend fundamentally 
on the provision of a better environment and the education of the people 
in physiological living. 
To attain this in the older civilisations will be a hard task, entailing 
enormous expenditure of money and energy. In the Report of the Royal 
Commission on the Housing of the Industrial Population of Scotland in 
1917 is described the unsatisfactory sites of houses and villages, insufficient 
supplies of water, unsatisfactory provision for drainage, the gross over- 
crowding in the congested industrial towns, occupation of one-room houses 
