294 THE VITAMINS 



McCoUum, Simmonds, Shipley and Park (1921, 1922) contrasted 

 cod-liver oil with butterfat in the protection given rats against the 

 effects of insufficient calcium in the diet. They stated that "cod-liver 

 oil contains in abundance some substance which is present in butter- 

 fat in but slight amounts, and which exerts a directive influence on 

 the bone development and enables animals to develop with an inadequate 

 supply of calcium much better than they could otherwise do. This sub- 

 stance is apparently distinct from fat-soluble A, which is essential for 

 growth and which is associated definitely with the prevention of 

 ophthalmia (keratomalacia)." 



The experimental evidence offered in their paper consisted chiefly 

 of feeding tests with rats upon diets poor in calcium (such as mixtures 

 of seeds with the addition of casein and sodium chloride) from which 

 they found that, "On a diet such as we employed, young rats are much 

 better nourished when supplied with 1% cod-liver oil than with 10 to 

 20 per cent of butterfat, as is shown by better growth, fertility, success 

 in rearing young, and in length of life. This is true, notwithstanding 

 that 3% butterfat is ample for providing the animals with sufficient 

 fat soluble A and any other organic substance exerting a special effect 

 on the bones when the content of calcium in the diet is raised to 

 approximately one-half the optimal. The provision of nearly seven times 

 this amount does not exert much protection against the specific detri- 

 mental effect of lack of calcium when the content of the diet in this 

 element is 1/15 to 1/5 or 1/6 this optimal amount. One per cent of 

 cod-liver oil, on the other hand, seems to increase in a very remarkable 

 manner the effectiveness with which the anatomic elements of the body 

 tissues deal with a very low calcium supply." 



In the light of the experiments of Sherman and MacLeod (1925) 

 it would appear that McCollum, Simmonds, Shipley and Park under- 

 estimated the importance of an allowance of vitamin A higher than 

 that which 3 per cent of butterfat would usually furnish, and therefore 

 in this paper may have attributed to the antirachitic vitamin some 

 nutritional effects which were really due to the greater amount of 

 vitamin A furnished by the cod-liver oil than by butter. However, a 

 greater calcium-conserving effect of cod-liver oil than of butterfat was 

 clearly postulated, and the attribution of this effect to a distinct "anti- 

 rachitic" vitamin rather than to vitamin A was supported by experi- 

 mental evidence. 



Their results, they attributed to "a substance which plays an im- 

 portant role in influencing the anatomic elements in the osseous tissue 

 and may be designated as a calcium-depositing or phosphorus-mobilizing 



