2 7 6 



Scientific Proceedings (116). 



of cod liver oil as contrasted with butter fat in influencing the 

 rate and extent of growth, and their effects on the histological 

 structure of the bones. This is well illustrated by the results of 

 restricting young rats to the following diet : 



Wheat 30.0 



Maize 19.5 



Rice (polished) 9.5 



Rolled oats 8.5 



Peas 8.5 



Navy beans 8.5 



Steak 10.0 



NaCl 1.0 



NaHCCb 1.5 



Cod liver oil 3.0 



This diet induces fairly good growth and fertility during at least 8 

 to 10 months, notwithstanding its deficiency in calcium. The 

 calcium content of this food mixture is 0.059 gms. per 100. The 

 optimum calcium content of this diet is reached when about 1.5 

 per cent, of calcium carbonate is added. The phosphorus con- 

 tent of this mixture is 0.3546 gms. per 100, and is not far from the 

 optimum content. This food mixture is slightly alkaline owing 

 to its content of sodium bicarbonate. 



This food mixture with butter fat to the extent of 3, 10, or 20 

 per cent, of the food mixture fails to induce an appreciable amount 

 of growth. With 20 per cent, of butter fat the animals gain but 

 a few grams in weight, look very inferior, become short and stocky, 

 and are rough coated. They usually die within a few months. 



This diet when 10 per cent, of casein is added, but without the 

 addition of either butter fat or cod liver oil, causes pathological 

 changes characteristic of rickety. With small amounts of cod 

 liver oil (3 per cent.) no rachitic changes are seen in the bones. 

 Even 20 per cent, of butter fat fails to effectively direct the growth 

 processes in the bones toward the normal condition. 



This food mixture containing 3 per cent, of butter fat and 1.5 

 per cent, of calcium carbonate is a highly satisfactory diet for the 

 promotion of growth to the full adult size, the maintenance of high 

 fertility throughout the breeding period in the females and the 

 successful nutrition of the young by the mothers. Even a fifth 



