VITAMINS — HOPKINS 267 



the time. Later, however, partly owing to the work of others and 

 partly to extended experiments of his own, Eijkman came to the 

 definite conclusion that there is present in rice polishings an indi- 

 vidual substance differing from the then known food constituents, 

 but essential to normal nutrition, though required in very small 

 amount. Even before Eijkman himself had come to this final con- 

 clusion, the work of others had made it probable, and by 1910 the 

 significant facts had become fully established. Among those whose 

 work contributed to their establishment must be mentioned : Grijns, 

 a countr3'man of Eijkman; Vedder and Chamberlain, of the Amer- 

 ican Medical Service ; and the British investigators Eraser and Stan- 

 ton, whose investigations were carried out in the Malay States. All 

 of these helped to prove that the preventative of beriberi is a definite 

 chemical substance, and the last mentioned in particular took pioneer 

 steps which were ultimately to lead later workers to a successful 

 isolation of that substance. 



Those who worked on beriberi during these years thought and 

 wrote as pathologists, with their attention primarily directed to the 

 causation and cure of a particular disease. Though doubtless the 

 suggestion for an extension of the kind of knowledge gained was 

 ready to hand, as a matter of fact their writings at first contained no 

 reference to the possibility that substances with the properties we 

 now attribute to vitamins might function widely and prove to be 

 necessary for the support of such fundamental physiological proc- 

 esses as growth itself. 



This more general and more physiological conception of the func- 

 tions of vitamins arose directly from the results of feeding animals 

 on experimental diets. If the assumption were right that proteins, 

 fat, and carbohydrates, together with essential minerals, are the 

 sole nutritional necessities, then these materials should support all 

 the functions of the body when each of them is supplied in a pure 

 form, no less adequately than when, in natural foods, they are con- 

 sumed in association with small amounts of many other substances. 

 The nutritional value of such purified materials supplied in artificial 

 dietaries was at one time the subject of many experiments. The re- 

 sults of these were uncertain and contradictory, owing to the fact 

 that purification was often not complete. It was not then realized 

 that substances present in extremely small amount may profoundly 

 affect the value of a diet. It is this circumstance that our present 

 knowledge of vitamins has made so clear. In 190&-7 the writer 

 engaged in feeding rats upon highly purified materials of the above 

 kind, and found them wholly unable to support health or normal 

 growth, though certain additions, very minute in amount, greatly 

 increased their nutritional adequacy. It happened that yeast ex- 



