V IT AMINES 281 



supply of the essential inorganic salts and certain other, as yet un- 

 identified, substances are necessary to permit of maintenance, growth 

 and repair. It has long been recognized clinically that certain diseases, 

 notably scurvy, may result from the absence of some essential in the 

 food supply. More recently other diseases have been proved to have 

 a similar cause, and the study of one of these, beriberi, has led to a 

 better appreciation of the nature of the food essentials concerned. 

 This disease seems to result from the use of polished rice as the chief 

 constituent of the diet, and can be checked by feeding unpolished rice, 

 or rice polishings, or even extracts of rice polishings, as first demon- 

 strated by Eijkman. A somewhat similar condition may be produced 

 readily in birds by feecUng them only polished rice, the chief feature 

 being a severe neuritis, which is relieved with remarkable rapidity 

 by supplying the food deficiency. This experimental neuritis of fowls 

 {polyneuritis gallinarum) has served as a valuable means of study of 

 diseases of this class, and led to the demonstration that not only ex- 

 tracts of rice polishings, but also many other food materials, contain 

 the essential materials without which health cannot be maintained. 

 One of the early investigators of this subject, Casimir Funk,^^ gave 

 to "the hitherto unrecognized essential dietary factors" the name "vi- 

 tamines," which, in spite of certain logical objections, has been widely 

 adopted; but as Lusk states, the term "food hormones" would be 

 preferable in our present state of knowledge. Although so essential 

 for life the amount required is very small, for whole rice is said to con- 

 tain not over 0.1 gm. per kilo, and perhaps much less, of the active 

 substance. 



McCollum^* has summarized the evidence that two classes of 

 substances are necessary for maintenance. These he designated, for 

 convenience, "/ai soluble A'" and '^water soluble B." It is the former 

 that is lacking in xerophthalmia, and the latter in poljmeuritis. It 

 now seems certain that other diseases are the result of deficiency in 

 other specific substances, ^^ particularly scurvy, which seems to result 

 from lack of a "water-soluble C." It also is an open question 

 whether under the water-soluble B are included two separate 

 vitamines, one antineuritic, the other growth-promoting.^^" 



As yet the exact identity of the active agents in water or fat solu- 

 tions has not been determined. The fat-soluble vitamines seem to be 

 especially abundant in butter, egg yolk, and cod liver oil, which pre- 

 sumably accounts for the commonly accepted values of these partic- 

 ular fats. They cannot be replaced by any of the known components 

 of fats, including phosphatids, lipochromes, cholesterol, etc.,^^ and 



'' See Ergeb. Physiol., 1913 (13 j, 125, for review of his work. 

 3" Jour. Biol. Chem., 1916 (24;, 491. 

 3» See Jour. Biol. Chem, 1918 (33), 55. 

 35»See Mitchell, Jour. Biol. Chem., 1919 (40), 399. 



36 See Drummond, Biochem. Jour., 1919 (13), 81; Palmer, Science, 1919 (50), 

 501. 



