SECTION I.—PHYSIOLOGY. 
PROGRESS AND PROSPECTS IN 
CHEMOTHERAPY. 
ADDRESS BY 
H. H. DALE, C.B.E., M.D., F.R.S., 
PRESIDENT OF THE SECTION. 
Introductory. 
In the mind of every physiologist visiting Toronto to-day one recent 
advance in our science will certainly be uppermost. We rejoice with our 
colleagues here in a great achievement which has opened new vistas of 
knowledge to exploration, has brought relief to unmeasured misery, and 
has turned the eyes of a world, too often careless of such things, in proper 
gratitude and well-founded hope to this University and its Medical School. 
Tnsulin, and its still marvellous and mysterious action, have held a promi- 
nent place in the interest of many of us, myself included, during the past 
year or two. In one of our meetings, however, we shall have the opportunity 
of considering the observations and opinions of many who are now working 
on its properties and their significance, and among them will be some who 
were associated with its discovery. I have thought it appropriate, there- 
fore, to ask your attention to-day to some recent developments in a widely 
different field of investigation. The subject which I have chosen presents 
points of general physiological and biochemical interest, apart from its 
immediately practical importance for the treatment of disease. It has, 
further, in one way, a special appropriateness to this year’s meeting of the 
British Association. For our knowledge of an important group of diseases, 
caused by the parasitic trypanosomes, which have provided the experi- 
mental material for a very large proportion of chemotherapeutic investi- 
gations, we are in the largest measure indebted to the pioneer work of the 
distinguished President of the Association, Sir David Bruce. 
I. The Theoretical Origin of Chemotherapy. 
Chemotherapy may be defined as the specific treatment of infections 
by artificial remedies. The object of those who study it is to find new 
remedies which will cure or arrest diseases due to infections, not b 
alleviating the symptoms or invigorating the patient, but by directly and 
specifically suppressing the infection. Chemotherapy, in this wide sense, 
is not entirely of recent growth. When the natives of Peru discovered the 
value in fevers of the cinchona bark, which the Jesuits brought to Europe 
in the 17th century, they had found a specific remedy for malaria, which 
is still the best available. Similarly the natives of Brazil had found in 
ipecacuanha, which reached Europe shortly after cinchona, a remedy for 
amoebic dysentery better than any other which our modern systematic 
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