244 



SCIENCE PROGRESS 



0«u» 20 



40 



60 



80 



100 



120 



140 



I feO 



160 200 2ZO 24-0 



Z60 280 



Fig. 15. — Rat on milk diet. The broken curve indicates normal growth of rat on ordinary 

 food. The dotted line shows amount of food eaten by rat. 



(From the Journal of Biological Chemistry, vol. xii. 1912.) 



inadequate to bring about the normal growth ot a young animal. 

 For growth to take place some other vitamine must be present 

 which is believed to be contained in the fatty portion of the 

 milk, i.e. in the portion that would constitute the ether-alcohol 

 extract found to be active in this respect by Hopkins. 



In the first example, fig. 12, the young rat was fed for 

 265 days on an artificial diet containing gliadin as its sole 

 protein. Dry protein-free milk was also added. The weight 

 of the rat very slowly increased. On the 266th day when the 



