results when the protein intake is 24 per cent is any higher than the level of calcium which gives the best results when the protein intake is 14 per cent. The present studies seem to indicate that the most beneficial level of calcium intake when the protein intake is liberal lies in the range of 0.4-0.6 per cent, or two to three times the level of minimal adequacy. In earlier studies,8 where calcium alone was added to Diet A, the level of optimum intake appeared to be at least three, and perhaps as much as four, times the level of minimal adequacy. Finally, it would seem justifiable to conclude that a diet liberal both in calcium and in protein is clearly superior to a diet liberal only in protein. * This work has been aided by grants to Columbia University, at first from the John and Mary Markle Foundation, more recently from the Nutrition Foundation, Inc., the Williams-Waterman Fund in the Research Corporation, and Swift and Company. t Deceased October 7, 1955. ' A comparison will soon be published of the life-histories of such late-generation Diet A animals with those of their ancestors whose families had been on the diet only about half as many generations and with those of their early forebears whose families had only recently been transferred to the diet.