On a high calcium low phosphorus diet, in which the moderate content of vitamin A and deficiency in D is supplemented by vitamins A and D, growth is retarded. The metabolism continues for 19 weeks to show a high calcium low phosphorus retention. The fat-free bones are normal in respect to the relative amounts of calcium and phosphorus which they contain. The body shows no alteration from the normal in respect to per cent of calcium and phosphorus and their relative proportion. The phosphorus deficiency of this diet causes delayed growth and is the limiting factor.