1. Renal concrements: average age at onset 39. Vesical concrements: average age onset 51 years
2. Male
3. Children dead in early infancy have been omitted
4. The experimental work of Osborne & Mendel and Fujimaki showing that deficiency of vitamiu A may cause stone-formation in rats does not seem tome to bear on our problem since the stones thus produced are composed of calcinmcarbonate and phosphates