The effect of changing in the direction opposite to that described above (Rations 3127, 3133 and 3143) the ratio between the calcium and phosphorus has been tested. A diet consisting of cereal grains, and legume seeds does not induce any growth because it is too poor in calcium. It is likewise deficient in phosphorus, but not in so marked a degree as in calcium. The content of fat-soluble A is also far below the optimum and its proteins are not of the best quality. The diet in question is No. 2638, described by Shipley, Park, Simmonds and McCollum (20).

Ration 2638.

Wheat ........................ 30.0

Maize ......................... 30.0

Polished rice ..................... 10.0

Rolled oats ...................... 10.0

Peas ......................... 10.0

Navy beans ...................... 10.0

If this diet is supplemented with common salt, calcium and fat-soluble A, it supports good growth and fair fertility. The animals are not normal, however, as is shown by subnormal fertility, high infant mortality, the short span of life, and the deterioration of families of animals restricted to it through several generations.

When young rats are confined to this diet without supplementing its calcium and protein content, they cannot grow, and are brought into a state of nutritional instability. They do not constantly develop distinct rickets, although the bones are not entirely normal and frequently suggest rickets. The addition of 10 per cent of casein, a phosphorized protein, enhances the food both with respect to phosphorus and amino-acids, yet when this is done severe rickets-like changes promptly develop provided no calcium is added to the diet. This is interpreted as a demonstration that addition of phosphorus, but without exceeding a concentration which is about the optimum under conditions where more calcium were available, may cause damage, when it leads to the establishment of an unfavorable quantitative relation between these elements. When casein and a calcium salt are added simultaneously, the diet is greatly enhanced and the bones tend toward the normal structure. They are, however, somewhat osteoporotic.

341. Rickets Is Essentially A Disease Of Dietary Origin

From what has been said of recent developments in the study of rickets, there can no longer be any doubt that it is a disease which is essentially due to nutritional disturbances, and that dietetic errors play the dominant role in its etiology. It is also clear that at least three dietary factors, calcium, phosphorus and an organic substance which is more abundant in cod liver oil than in any other substance known, are especially important in that rickets will develop unless proper amounts of these be furnished to the growing animal. Other factors may favor or interfere with the development of the disease.