REGULATORY SUBSTANCES 513 



so and so many quarts of "lime" juice per man per month of 

 voyage. The "Umes" were lemons, and the juice was to prevent 

 scurvy. Today, with modern nutritional methods and shorter 

 voyages, this precaution is not necessary, though scurvy still 

 occurs where fruits, vegetables, and fresh meats are not available, 

 as, for example, in arctic regions. In spite of the knowledge 

 that lemon juice prevents scurvy, it was not until 1897 that the 

 first successful experiment on vitamins was done and not until 

 as recently as 1910 that the significance of this experiment was 

 fully understood. 



In 1891, Bunge stated that there must be present in milk sub- 

 stances other than casein, fat, lactose, and salts which make milk 

 a suitable food. Six years later, Eijkman found that fowl 

 restricted to a diet of polished rice developed polyneuritis, the 

 analogue of beriberi in man. He then discovered that the 

 coating on rice contained something that prevented the disease. 

 Funk, in 1910, repeated Eijkman's work and gave the word 

 "vitamin" to those specific substances which are essential to 

 normal nutrition and prevent disease. Simultaneous with this 

 work was that of the dieticians who found that purified proteins, 

 carbohydrates, fats, and salts are not sufficient for growth in 

 animals. E. V. McCollum, the foremost worker on vitamins in 

 America, found, with M. Davis, that certain fats, e.g., butterfat 

 and egg-yolk fat, contain some substance that is essential to 

 growth, while olive oil and lard do not contain this substance. 

 Later, Osborne and Mendel added cod-liver oil to the former two. 

 The substance in these fats necessary for normal growth is now 

 known as vitamin A. At least 6 essential vitamins are recog- 

 nized, and 10 have been named. 



The term vitamin may be applied to any substance that is 

 indispensable for normal growth and good health in respect to 

 some special function such as the prevention of a specific disease. 

 Vitamins are distinguished from hormones in that the latter are 

 usually produced within the body, while the former are supplied 

 in the food. The vitamins are lettered A, B, C, etc., and further 

 characterized as fat or water soluble. Though some are abun- 

 dant in animal tissues, plants are the chief source; for this reason, 

 vitamins have received the name of plant hormones. (The 

 prevailing opinion is that vitamin A is not found in plant tissue ; 

 only carotene, the precursor, is so found.) 



