328 THE VITAMINES 



Hess, McCann and Pappenheimer (I.e. 1135b) maintain that a 

 lack of vitamine A is not followed by rickets in rats. This is con- 

 trary to the findings of Mellanby in dogs, and shows perhaps that 

 butter is very poor in vitamine A [in agreement with the observa- 

 tions of Zilva and Miura (I.e. 574a)] and that dogs and rats show 

 great quantitative differences with respect to their vitamine A 

 requirements necessary to influence bone growth. In this con- 

 nection, the vitamine A of butter is less resistant than cod liver oil 

 towards oxidation. In confirmation of this, there is the work of 

 Turk (1135c) that melted butter exposed to oxidation does indeed 

 increase the immunity of children towards infections but does not. 

 protect against rickets. 



In a recent publication, McCollum, Simmonds, Shipley and Park 

 (1135d) have attributed to cod liver oil a specific role in rickets. 

 The vitamine contained therein doesn't seem to be identical in its 

 influence with vitamine A, but perhaps it is a question of quantita- 

 tive relationships. On the addition of cod liver oil the calcium and 

 phosphorus requirements of the animals were markedly reduced. 

 A similar result was obtained on the administration of phosphorus. 



On a critical consideration of the vitamine theory of rickets it is 

 apparent that on a certain diet which must be regarded as leading to 

 rickets, not all children develop the disease. On the other hand, a 

 large percentage of the cases may be cured by cod liver oil, but not all 

 cases. Individual differences arise here which can not be explained 

 at present, though we firmly believe that we are on the right track. 

 Recently, of the French investigators, Nathan (1136) has adopted 

 our view. 



Undoubtedly, rickets may be brought into causal relationship with 

 vitamine A, although the above-mentioned factors are also of signifi- 

 cance. In accord with this, there is the fact that the manifestations 

 of rickets in children, in certain periods of the year, are more marked 

 than in others. Sometimes, as Dr. Hess has told us, spontaneous 

 cures occur in spring. One might be tempted to associate this with 

 seasonal variations in the vitamine content of milk, as has already 

 been partially demonstrated. The influence of light is also to be 

 considered in this respect. Hess and Unger believe in the specific 

 action of cod liver oil, but not of milk fat. We cannot agree with 

 this since it would mean that normal milk contains no substance 

 protective against rickets, and, therefore, most milk-fed children 



