32 THE PRESIDENTIAL ADDRESS. 
quantity of a vitamin may determine growth and health or disease and 
death, so an extremely minute quantity of glandular secretion may have 
a similar effect. 
The anterior lobe of the pituitary gland is a very small body, yet an 
excess of its secretion will cause a child to grow into a giant; a deficiency, 
and the growing child will remain an infant. 
The best known of the ductless glands is the thyroid, and the effect of 
its secretion is truly marvellous. A deficiency, and the child grows up a 
heavy-featured, gibbering idiot. Rectify the supply of thyroid secretion : 
the heavy features disappear, the eyes brighten, the intelligence returns, 
and instead of the former heavy-jowled imbecile you havea bright, happy 
and normal schoolboy. 
On the other hand, if there is an excess of the thyroid hormone, 
exophthalmic goitre, or Graves’s disease, is the result. Remove the 
redundancy and health returns. 
The active principle of the thyroid has lately been shown to be a com- 
pound containing iodine. If there is no iodine in the soil or water, goitre 
is the result, as in parts of Switzerland, Canada, and the United States. 
This aspect of the subject was taken up some ten years ago by Dr. David 
Marine and his colleagues at Cleveland, Ohio. They find that endemic 
goitre may be prevented by the simple method of giving for a time minute 
doses of iodine, and conclude that with this simple, rational, and cheap 
means of prevention, this human scourge, which has taken its toll in misery, 
suffering, and death throughout all ages, can and should be controlled, if 
not eliminated, and look forward in imagination, a few generations hence, 
to the final closing of the chapter on endemic goitre and cretinism in 
every civilised nation in the world. 
Many advances have also been made in our knowledge of the function 
and uses of other ductless glands, and, as you know, the latest victory 
in this field is the discovery of insulin and the successful treatment of 
severe diabetes, for which magnificent work your own townsmen Banting 
and Best deserve the highest honour. 
Inmany otherdirectionsthanthose touched upon has there been progress 
in the prevention of disease. It would take more than one address to 
describe the activities of the Rockefeller Foundation alone. Campaigns 
for the relief and control of hookworm disease, malaria control, the eradica- 
tion of yellow fever, anti-tuberculosis work and education are being pursued 
on such a scale and at such a lavish expenditure of money as to leave us 
in the Old Country breathless with admiration and envy. 
