VITAMINS. 1 



By W. D. Halliburton, 

 London, Kings College, Physiological Laboratory. 



The word "vitamin" is not as old as the present century, and 

 though it is not altogether a satisfactory term, it has obtained a 

 permanent footing in scientific and medical literature. The expres- 

 sion " accessory food factor," which has been suggested as a sub- 

 stitute, is certainly more cumbersome. But, after all, it is a matter 

 cf small moment what word is used ; the important point is what it 

 connotes. 



It is a matter of everyday physiological knowledge that our bodies 

 are built out of proteins, fats, carbohydrates, salts, and water, and 

 these substances must be present in the food in certain proportions 

 and in sufficient quantities to repair the body waste and furnish the 

 energy necessary for its activities. But recent research has shown 

 that these substances alone are incapable of maintaining life. Some- 

 thing else is required, the chemical nature of which is at present un- 

 known, and it is to these unknown but indispensable accessory sub- 

 stances that the term " vitamins " has been applied. 



Prof. F. G. Hopkins, of Cambridge, a pioneer in this branch of 

 research, has suggested a useful simile to help us to understand the 

 problem. He compares the building of the body to the building of a 

 house. The essential bricks or blocks of stone of which the walls of 

 the house are composed would be of comparatively little use unless 

 cement were also supplied to unite these components together, and it 

 is the cementing material which he compares to the vitamins. It 

 would be dangerous to press such an analogy too far, for the exact 

 role of the vitamins is still hidden from us. But the simile is a use- 

 ful one to indicate one way at least in which they can render the im- 

 portant building stones of real service, and it is accurate in a quanti- 

 tative sense. The cement in the walls of a house makes up but a 

 small proportion of the structure. It is exactly the same in the case 



1 Reprinted by permission from " Scientia," vol. XXVII. 1920. 



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