340 HUMAN BIOLOGY 



than is the antlneuritic vitamin b. Vitamin f is much more 

 stable to heat than vitamin b, a fact which was instrumental 

 in bringing about its discovery. Yeast, lean meats, leafy 

 vegetables and milk are among the common foods available 

 in abundance which are potent in vitamin f, the most 

 important being the fir'st named. Other common foodstuffs 

 cannot yet be classified as to their values in preventing 

 pellagra. 



During the last fifteen years Dr. Simmonds and the 

 writer have given much attention to the study of human 

 dietaries in different parts of the world. The results can 

 be furnished briefly as follows: Successful human dietaries 

 are found in three types of geographic environment. In the 

 coldest parts of the earth mankind subsists essentially 

 upon a carnivorous diet. The Eskimos of Northwest Green- 

 land hve mainly upon birds, eggs and seals. They eat no 

 land animals and fish only for a few weeks in mid-summer. 

 Although small, they are very hearty people and have 

 held their own under the most unfavorable conditions of 

 chmate through many generations. It is interesting that 

 they have excellent bones and that their teeth rarely decay. 

 It should be emphasized that they eat glandular organs as 

 well as other parts of the creatures which serve as food. 



In the warmest regions of the world, which are also 

 characterized in general by excess of wetness, live the rice- 

 eating peoples. Their diet is in the main vegetarian and 

 consists of rice as the principal cereal, with additions of 

 soy beans, various tubers and root vegetables, and large 

 amounts of leafy vegetables of many kinds. These include 

 Chinese cabbage, leaves of sweet potato, bamboo sprouts, 

 water cress, spinach and other similar vegetables. The 

 leaf of the plant is superior to the seed, tuber, root or fruit 

 In its dietary properties. In fact, the edible leaf is in itself 

 complete from the standpoint of its dietary principles. 



In 19 1 5 the writer and Miss Davis described a procedure 

 consisting of a properly planned series of feeding experiments 

 in which a single natural food is supplemented singly or in a 

 multiple fashion with known nutrient principles, such sup- 

 plementing increasing in complexity as the series is extended 

 until it Is discovered what constitutes the fewest additions 



