904 NUTRITION AND HEAT REGULATION. 



without in the protein food. It is to be hoped that continuation 

 of this work will reveal ultimately the nature of the chemical reac- 

 tions of maintenance and growth. 



Vitamines and Other Special Substances. From the state- 

 ments made in the preceding paragraphs of this chapter one might 

 conclude that a perfect food would be one which supplied enough 

 non-protein material (fats and carbohydrates) for the energy needs, 

 all the necessary amino-acids, and the essential amounts of water 

 and inorganic salts. This conclusion has been made doubtful by 

 much recent work, which tends to show that in addition to these 

 fundamental requisites there are certain accessory materials that 

 are necessary, either because they play some essential role in the 

 syntheses of the body or influence in some more indirect way the 

 normal direction and character of the metabolism. This unex- 

 pected result may be illustrated best by reference to the condition 

 known as beriberi. Beriberi is a disease that occurs chiefly among 

 oriental nations that make great use of rice as a food. The dis- 

 ease takes a variety of forms, but the characteristic symptoms are 

 paralyses, and atrophy and contractures of the limbs. It has been 

 shown that the condition is caused by limiting the diet exclusively 

 or mainly to polished rice, that is, to rice from which the outer 

 layers of the grains have been removed. If the polishings are 

 restored to the diet the condition disappears, or if other materials, 

 such as meat and barley, are used with the polished rice the disease 

 does not occur. The interpretation placed upon these results 

 is that the polishings contain some constituent essential to body- 

 metabolisms. This conclusion has been much strengthened by 

 experiments on fowls. When these animals are fed exclusively on 

 polished rice they develop a condition (polyneuritis) similar to 

 beriberi and soon die. They may be saved by adding the polishings 

 to the diet or by changing the diet. Funk has shown that from 

 the polishings of rice, and from many other of the ordinary foods,, 

 there can be isolated a relatively simple nitrogenous base which 

 seems to resemble in structure the pyrimidin bases found as one 

 component of nucleic acid.* He designates this base as vitamine,. 

 and experiments show that when administered to an animal or 

 patient exhibiting the symptoms of beriberi these symptoms dis- 

 appear. On the basis of this and similar work, Funk suggests; 

 that not only beriberi, but other forms of disease which seem 

 to belong to the same class, are due to a deficiency of vitamines 

 in the diet. Scurvy and pellagra may belong in this group, and 

 it is suggested that there may be in our foods several of these 

 vitamines, each with some special role to play. They exist in the 

 foods in very small quantities and their physiological importance 



* For a general statement with literature see Funk, "Ergebnisse der Phys- 

 iologic," 13, 125, 1913. 



