THE PRESIDENTIAL ADDRESS. 3 
juice was caused by a living cell and that certain contagious skin-diseases 
were associated with living fungi. 
Things were in this position when there appeared on the scene a man 
whose genius was destined to change the whole aspect of medicine; a 
man destined to take medicine out of the region of vague speculation and 
empiricism, and set its feet firmly on new ground as an experimental 
biological science. I mean the Frenchman, Louis Pasteur. It is from him 
we date the beginning of the intelligent, purposive prevention of disease. 
It was he who established the germ theory, and later pointed the way to the 
immunisation of man and animals, which has since proved so fruitful in 
measures for the prevention or stamping out of infectious diseases. 
I need not discuss his life and work further. His name is a household 
word among all educated and civilised peoples. Every great city should 
put up a statue to him, to remind the rising generations of one of the 
greatest benefactors of the human race. 
What the change in medicine has been, is put into eloquent language 
by Sir Clifford Allbutt: ‘ At this moment it is revealed that medicine has 
come to a new birth. What is, then, this new birth, this revolution in 
medicine ? It is nothing less than its enlargement from an art of observa- 
tion and empiricism to an applied science founded upon research ; from 
a craft of tradition and sagacity to an applied science of analysis and law ; 
from a descriptive code of surface phenomena to the discovery of deeper 
affinities ; from a set of rules and axioms of quality to measurements 
of quantity.’ 
With one notable exception, the medical profession were not quick 
to see that Pasteur’s discoveries of the nature of fermentation and 
putrefaction had a message for them. This exception was Joseph Lister, 
who had been for some years endeavouring to comprehend the cause of 
_ Sepsis and suppuration, which commonly followed every surgical operation 
and most serious injuries involving a breach of the skin. 
When, in 1865, Lister read Pasteur’s communication upon fermentation, 
the bearing of the discovery on the problems which had so earnestly 
engaged his attention was apparent to him. He inferred that suppuration 
and hospital gangrene, the causes of which had so far baffled his imagina- 
tion, were due to microbes introduced from the outside world, from the 
air, and by instruments and hands of the operator. Remember, this was 
years before the microbial causation of any disease was established. 
To test the correctness of his inference, Lister proceeded to submit all 
instruments, ligatures, materials for dressings, and everything that was 
B2 
