394 THE VITAMINES 



as being opposed to such preparations, maintaining that the natural 

 foodstuffs may be used in the therapy and the prevention of avitam- 

 inoses. In the light of our present knowledge, this appears indeed 

 to be the case. Still, we do not know how this matter will develop 

 in the future, and the question can be studied only then when the 

 vitamines will be obtained in the pure or highly concentrated state. 

 It is possible that such pure products may manifest properties at 

 present neither known nor. even suspected. For example, on com- 

 paring the influence on rickets of vitamine A of butter and cod liver 

 oil, it was found that only the latter can prevent the occurrence of 

 the disease; one might therefore be tempted to regard the two sub- 

 stances as individual chemical entities. As a matter of fact, if 

 it is true that cod liver oil is about 250 times richer in vitamine A 

 than is butter, the above difference may perhaps be only 

 one of concentration. Although most commercial products cannot 

 withstand sharp scrutiny, it would be desirable not to decry the 

 present concentration and purification experiments, since they may 

 perhaps lead to interesting and important results. 



