148 PRESIDENT’S ADDRESS—SECTION I. 
is, in countries where full and proper use is made of vaccination. 
Encouraging results have already been obtained in the direction 
of cure or prevention in cholera, plague, yellow fever, typhoid, 
by methods of inoculation, though the evidence has not yet the 
same cogency as in the case of diphtheria. That a new era has 
been opened in the science of preventive medicine we cannot 
doubt. 
Typhoid fever is a disease which has long been unduly pre- 
valent in Victoria, and particularly in Melbourne. There was 
some reason, if not full excuse, for this condition of affairs, at 
least as regards Melbourne, in the fact that the metropolis of the 
colony had grown rapidly into a populous city, spread over a 
large area, with such fouling of the soil as must inevitably result 
where drainage facilities are defective. There need be no diffi- 
culty in accepting the belief that milk or water, accidentally 
contaminated with the virus of typhoid, may be the means of 
spreading the disease. Milk epidemics, happily of no great ex- 
tent, have occurred occasionally in Melbourne, as in other parts 
of the world. Contaminated water has also been suspected of 
‘acting in a similar way, though on less exact evidence. It is a 
mistake, however, to assume, as seems sometimes to be done, that 
water and milk are almost the sole means or agency by 
which the disease is spread. I have always held that 
this foulness of the soil had much to do with the persis- 
tent prevalence of this typical filth disease. Recent investiga- 
tions in England have shown that the specific bacillus of 
typhoid is capable of multiplying in the soil, when favourable 
conditions for its growth are present, in respect to moisture, 
heat, and organic defilement, especially of animal origin. There 
is good reason to believe that the prevalence of typhoid in 
Adelaide and Sydney has been greatly reduced by the extension 
of drainage operations, and the consequent purification of the 
soil around dwellings. Typhoid is a disease with very marked 
differences in its prevalence and fatality in successive years or 
periods. Ten years ago I thought there were distinct indications 
that the disease had a four-yearly periodicity. I made an 
endeavour to discover whether anything in meteorological con- 
ditions could be brought into relation with that periodicity. 
whether regular or not. I had to confess to a failure, though I 
felt driven to the belief that some such conection there must be. 
The periodicity has been less regular of late years, and it is a very 
natural suggestion that this disturbance of rhythm might be 
due to the extensive breaking of the surface which attended the 
great building operations of the land boom, and to those con- 
nected with the sewerage works. Taking the notifications of 
cases of typhoid in the months of November and December, we 
find that in 1899 the cases noted were fewer than in any pre- 
vious year. But 1893 was almost as low, and, as there were 
