278 THE MAINTENANCE OF THE INDIVIDUAL 



These health regulators have been lettered and are known as 

 Vitamins A, B, C, D, E, and G. More recent experiments show that 

 what was previously believed to be a single vitamin may prove to 

 be a mixture of two discrete fractions. These may be referred to as 

 A\ A^, and so on, or they may be given a new letter, as, for example, 

 H. Thus Vitamin B has become subdivided into B or B^ the anti- 

 neuritic vitamin, the absence of which results in a disease known as 

 heriheri, and B- or G, the antipellagric vitamin, the lack of w^hich 

 produces pellagra. 



The initiation of scientific work in this field is usually credited to 

 Eijkman, who in 1897 produced beriberi in fowls by feeding them on 

 certain restricted diets. This was really "putting the cart before the 

 horse," for through the pioneering contributions of Grijns (1901) it 

 was shown that the disease is produced by the absence of some essential 

 constituent of the diet. This important conclusion has been corrob- 

 orated and extended materially through the efforts of Hopkins in 

 England and McCollum, Eddy, Osborne, and Mendel in the United 

 States. Research in this field has taken great strides since 1910 and 

 is still going on. 



Vitamin A is found in the fatty and oily constituents of such 

 foods as butter and cream, egg yolk, liver, carrots, cod-liver oil, 

 yellow corn, and leafy vegetables. Experiments have demonstrated 

 that this vitamin is a necessary adjunct to growth. Without it rats 

 die, but if even such minute amounts as 0.005 mg. of the purified 

 vitamin are added to the normal diet, the sick animals are restored 

 to general health. 



Scurvy has long been the curse of those embarking upon long sea 

 voyages or expeditions where it has been necessary to provide diets 

 deficient in fresh meats and vegetables. It has also been known that 

 such a disease can be cured by the use of fresh vegetables and fruits. 

 As early as 1804, lemon juice was issued regularly to British sailors, 

 who became known thereafter as "limeys." It is only within com- 

 paratively recent years, however, that this remedy has been known to 

 be due to the presence of Vitamin C, the antiscorbutic vitamin. It 

 may be secured most conveniently in oranges, lemons, or tomatoes. 

 Apparently food can be dried or canned without marked injury to 

 the vitamin. Almost as soon as this vitamin is eliminated from the 

 diet degenerative changes begin, although some time is necessary 

 before the first symptoms appear. This has been designated as the 

 depletion period. 



