January 31, 1913] 



SCIENCE 



189 



imal quantity of tryptophane is essential for 

 life, and that this is not supplied by these 

 smaller proportions of oasein or edestin. 



Thus far the experiments I have described 

 iave been concerned with zein, which is only 

 ■one of the proteins of maize. 



formed the sole protein. On this diet the rat 

 quadrupled its weight in TO days, thus exceed- 

 ing somewhat the average normal rate of 

 growth of rats on natural mixed food. Eat 

 596 grew more slowly on a diet containing 

 equal parts of zein and maize glutelin. 



Chart VI. shows that corn contains a pro- 

 tein which is capable of promoting normal 

 growth. During period 2, rat 567 was fed 

 with a diet containing the same non-protein 

 ■constituents as those used in the preceding 

 experiments, but in this food maize glutelin 



Chart VII. shows the result of feeding rats 

 with corn gluten. This substance is a prod- 

 uct obtained in the manufacture of corn 

 starch, and consists chiefly of zein and maize 

 glutelin, which are separated from the corn 

 by purely mechanical operations. With this 



