VITAMINE 



239 



for each of a series of rats under observation being then 

 calculated. 



In the preliminary work it was found that the rats devoured 

 large quantities of the artificial food ; but they did not grow 

 until a modicum of milk was also added. The nature of the 

 results can perhaps best be made clear by means of graphic 

 representations taken from Hopkins's published work in the 

 Journal of Physiology, vol. xliv. 191 2. In fig. 9 we have the 



18 2S 5"0 Days 



Fig. 10. 



White circles : — Rats on artificial diet alone. 



Black circles : — Rats on artificial diet alone + 3 c.c. milk per rat per diem. 



(From the Journal of Physiology, vol. xliv. 1912.) 



record of the average weight of six rats fed on artificial food 

 compared with the average weight of six other rats similarly 

 treated, but receiving in addition 2 c.c. of milk per rat per 

 diem. The blackened circles denote the set receiving milk, 

 whilst the light circles constitute the record of the set fed on 

 the artificial diet alone. In these experiments the constituents 

 of the diet were first carefully purified to eliminate traces 

 of activating substances before being mixed together to form 

 the basal artificial food. 



