\nA.\u\Ei^ 287 



beri, lias led to a closer approximation to the nature of the food essen- 

 tials concerned. This disease seems to result from the use of pol- 

 ished rice as the chief constituent of the diet, and can be checked by 

 feeding unpolished rice, or rice polishings, or even extracts of rice 

 polishiugs. A somewhat similar condition may be produced readily 

 in birds by feeding- 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 extracts of rice 

 polishings, but also many other food materials, contain the essential 

 materials without which health cannot be maintained. One of the 

 earl}' investigators of this subject, Casimir Funk,^"' gave to "the 

 hitherto unrecognized essential dietary factors" the name "vitamines, " 

 which, in spite of certain logical objections, has been generally adopted. 

 Although so essential for life the amount required is very small, for 

 whole rice is said to contain not over 0.1 gm. per kilo., and perhaps 

 much less, of the active substance. Besides beriberi, the following 

 may be considered as of the nature of ' ' deficiency diseases ' ' : Scurvy 

 and infantile scurvy (Barlow's disease) and possibly pellagra, rick- 

 ets and tetany. Furthermore, the "vitamines" are necessary for 

 growth, no matter how much and what proteins, carbohydrates and 

 fats are supplied. 



McCollum '■^ has summarized the evidence that two classes of sub- 

 stances are necessary for maintenance, the more important in pre- 

 venting neuritis' being water-soluble, although for growth to occur an 

 unidentified lipoid-soluble substance is essential. As yet the exact 

 identity of the active agents in water or lipoid solutions has not been 

 determined, but the pursuit is being gradually brought closer to the 

 goal. Funk believed them to be pyrimidine derivatives. AVilliams 

 and Seidell ^^ have found that hydroxypurines have marked anti-neu- 

 ritic effects, and they suggested that an isomer of adenine is responsible 

 for the antineuritic action of yeast extracts. Later Williams ^''"^ 

 found an active hydroxypyridene, and suggested that the curative 

 properties of yeast and rice polishings may be due to an isomeric form 

 of nicotinic acid. The lipoid-soluble "vitamines" seem to be especially 

 abundant in butter, egg yolk, and cod liver oil, which presumably ac- 

 counts for the commonly accepted values of these particular fats. 

 Why the vitamines are essential and how they act is unknown. Ved- 

 der ^^ has suggested that the antineuritic vitamine is essential for 

 growth and repair of the nervous tissue, and in its absence normal 



15 See Ergeb. Phvsiol., 1913 (13), 12.i, for review of liis work. 

 ifiJour. Biol. Chem., 1916 (24), 491. 



17 Jour. Biol. Chem., 1916 (26), 431. 

 17a Jour. Biol. Chein., 1917 (29). 49"). 



18 Jour. Amer. Med. Assoc, 1916 (67), 1494. 



