IN addressing the graduates in medicine at the graduation ceremonial at the University of Edinburgh on July 18, Prof. A. J. Clark pointed out that to-day the prevention of disease, or its cure at an early stage, is becoming the chief function of the doctor. It is more interesting to try to enable the human machine to work with full efficiency than to patch up human wreckage so that it can just continue to function, but undoubtedly the diagnosis and treatment of slight deviations from the normal present problems of exceptional difficulty. Another point worthy of notice when considering their future careers, is that the demands of the public will be further modified by inevitable changes in the composition of the population. The figures for the birth rates during the last few years show that the average size of the family in the near future will be nearer two children than three. At first sight, it might appear that this diminution in the number of children will seriously curtail an important section of medical practiceobstetrics and the care of children. But the fewer the children, the more precious will they be, and though childbirth will be less common it will require more skilled assistance, hence these changes will not cause a proportionate decrease in the demands on the medical profession. The steady increase in the number of persons over sixty-five years of age, that has commenced already, is bound to have a very marked effect on medical practice, for the human body, though a marvellous machine, is not immune to the wear and tear of life and hence requires increasing attention in old age. One outstanding change in medical practice in the future is likely to be a rapidly increasing demand for skilled assistance to combat the minor disabilities of old age.