Vitamines
nitrogenous bodies which occur in certain foodstuffs. They were first discovered in 1912 by Gowland Hopkins in milk, and although their exact chemical nature is still, to a large extent, a hidden mystery, their enormous importance in the process of nutrition is well recognized. Three distinct types of vitamines have been discovered, and all three must be present in food in order that proper growth of the animal body may take place and that certain diseases may be avoided. The three types are known as (1) Fat-soluble A, or growthpromoting vitamines; (2) Water-soluble B, or anti-neuritic vitamines; (3) Watersoluble C, or anti-scorbutic vitamines. Fat soluble A occurs in butter, in various animal oils, such as whale-oil and cod-liver oil, and in many vegetables, especially in spinach, but is not found in refined vegetable oils. For this reason, butter is preferable to vegetable margarines, especially for growing children. Water soluble B is found in the embryo of cereals, while one of the richest sources of this vitamine is yeast. Watersoluble Coccurs in many fruits and vegetables, orange and lemon juices being especially rich sources. An immense amount of experimental work has been carried out to demonstrate the important rôle which vitamines play in the process of nutrition, of which the following are a few examples: E. Mellanby found that puppies fed on a diet deficient in fat-soluble A rapidly developed rickets, but when butter or cod-liver oil was added to their diet, the symptoms quickly disappeared. Pigeons and cats when deprived of water-soluble B develop polyneuritis, but rapidly recover when fed small quantities of yeast or extracts of yeast. A very striking illustration of the effect of water-soluble B occurred during the World War. In December, 1915, there was an outbreak of beriberi among the British troops in Mesopotamia, but among the Indian troops in the same region the disease was practically unknown. The theory was put forward that the difference was due to the fact that the British troops were fed highly refined white flour, while the Indian troops used a flour containing the germ and the aleurone layer. During 1916 the British troops were given a ration of yeast extract. In the following winter, instead of a second outbreak of beriberi, there were only a very few mild cases and not a single death. Many similar experiences have occurred. The Indian troops in France suffered severely, for a time, from scurvy, due to the soluble C, or anti-scorbutic vitamine. The addition of fresh limes to their diet resulted in a marked falling off of the disease.