40 BIOLOGICAL PROBLEMS 



to growth and the maintenance of health, but small 

 quantities suffice for these purposes. 



The term "vitamine' has been adopted in popular 

 usage, and its convenience is certainly great. It was 

 originally invented by Funk, when he thought he had 

 isolated a substance of definite chemical composition; 

 when this was found not to be the case, the word 

 "vitamine' fell into disrepute, as seeming to imply 

 more knowledge than we possess. Many scientists 

 consequently prefer the more non-committal term 

 * ' accessory food-factor ". 



Before plunging into this subject in its war-time 

 aspect, it is necessary to give as short a summary as 

 possible of the existing knowledge concerning vita- 

 mines, for it is impossible to grasp the difficulties 

 which arise in war-time in connection with them 

 unless something of their properties and distribution 

 among food-stuffs is first understood. 



The work on accessory food-factors falls rather into 

 two schools, of which one has dealt with them in con- 

 nection with the deficiency diseases (beriberi, scurvy, 

 rickets, and pellagra), and the other has dealt with 

 them as factors in growth. Whether, however, there 

 really are any accessory factors which are necessary 

 for growth and not also necessary for prolonged main- 

 tenance is a point which is not fully cleared up. 



In connection with the deficiency diseases two fac- 

 tors are clearly recognized, the one in the absence of 

 which beriberi develops, called the anti-neuritic or 

 anti-beriberi vitamine, and the one in the absence of 

 which scurvy develops, the anti-scorbutic vitamine. 

 There is a very strong probability that there are also 

 other accessory food-factors, deficiency of which causes 

 rickets and pellagra. It will be necessary to allude 

 briefly to rickets again, but there is at present no real 

 proof that pellagra is a deficiency disease at all, and, 



