286 SCIENCE REMAKING THE WORLD 



and cereal diet. Look to your green stuffs. But let 

 us learn to pick our vitamins out of the food market and 

 there will be no need to go to the druggist. 



A final word is perhaps desirable to explain the com- 

 pilation of a table such as shown above. How is such 

 information obtained ? No other discover}' emphasizes 

 more strikingly the value of animal experimentation 

 as a means of furthering human knowledge. Until 

 Eijkman discovered that beri-beri could be induced in 

 fowls, no tool was available for measuring quantita- 

 tively the amounts of the anti-beri-beri vitamin in 

 foodstuffs. The white rat has provided all the data 

 for distribution figures in regard to vitamin A and much 

 for B. To the guinea pig the race is indebted for the 

 proof of presence and quantity distribution of vitamin 

 C. If we can find an animal in which we can induce 

 pellagra, that controversy may be cleared up. In 

 brief, then, several methods of experimentation are 

 now in universal use in the study of vitamin nature or 

 distribution, but all are alike in principle. They all 

 consist in either feeding to the experimental animal a 

 diet lacking in a given factor and then attempting 

 cure by addition of the foodstuff under investigation, 

 or incorporating the foodstuff in the original diet in 

 varying amounts and noting the prevention or lack of 

 prevention of symptoms that follow. In all these diets 

 the principles laid down in our original list are utilized 

 and are essential if we are to be sure the results measure 

 vitamin deficiency. 



We end then, as we began, with reiterating that the 

 vitamin hypothesis has not destroyed old ideas about 



