THE DISTRIBUTION OF ACCESSORY FOOD FACTORS 

 (VITAMIXES) IN PLANTS. 



By E. Marion Delf, D.Sc, F.L.S., 



liesident Lecturer in Botany, Westfield College, University of London; 



Temporary Lecturer in Botany in the University of Capetown; late 



Yarrow Itesearch Fellow of Girton College, Cambridge; and Temporary 



liesearch Assistant in the Lister Institute of Preventive Medicine. 



Read Jahj 17, 1920. 



Twenty years ago, when the rate of increase of the human 

 race led certain scientists to predict a total insntficiency of the 

 world's food supplies m the near future, Berthellot, a g*reat 

 French chemist, foretold that bread, meat and vegetables would 

 soon be replaced by food tabloids, a dinjier menu, tor instance, 

 reading : — 



Small tablet nitrogenous matter. 



Pastilles fatty matter. 



A little sugar. 



Seasoning. 

 It was indeed, until recently, a firmly established idea that the 

 necessary elements of a perfect diet could be obtained from 

 chemically pure carb(diydrates, proteins and fats, with a few 

 mineral salts. In 1912 liopkins found, when breeding rats on 

 an artificial diet of this kind, that the more perfectly purified 

 the constituents of the diet, the less were they able to support 

 life. Young rats ceased altogether to grow and older animals 

 grew thin and finally died when kept altogether upon chemically 

 pure foods, whereas the addition of minute amounts of fresh 

 milk caused an immediate improvement and an increase in body 

 weight altogether out of proportion to the increase of the food 

 intake of the animals. AYe now know that the addition of a 

 small amount of butter fat or of fresh green food would have 

 had a similar eftect. and it is abundantly clear that, in addition 

 to the recognised foods, small amounts of other unidentified 

 substances are necessary to health and are present in fresli 

 natural foods. These substances are known as vitamines or as 

 accessory food factors ; they are unstable under chemical treat- 

 ment and can be detected at present only by biological tests. 

 They have been the subject of much research in England and 

 America, especially since the increase of deficiency diseases in 

 Europe owing to improper and restricted diets' under war 

 conditions. 



All the evidence points to tlie plant as the ultimate source 

 of these accessory food factors. Their distribution in the plant 

 world may be roughly summarised as follows: — 



1. The Anti-neuritic Yitamixe (usmlly identified as the 

 water soluble growth factor). 



