Dr. James Mackenzie in his invaluable work on diseasesof the heart says: The investigators in hospital wards and laboratories have little idea of the difficulties the general practitioner has to encounter. He must ever be on the alert, prepared to make an observation at any hour of the day and night attacks of illness which may arise suddenly must find him prepared to take advantage of his opportunities. He goes on to say, The little I have been able to do in this respect has but opened my eyes to the extraordinarily rich field for investigation that lies before the general practitioner.