FEEDING EXPERIMENTS WITH MICE 217 



gained 8 grams, lost all its dwarfish look and weakness. The 

 mouse subsequently remained healthy for eighty-two days on the 

 casein food used at first, but gained in all that time less than 

 3 grams. In recovery from inadequate diets, the body weight 

 never rose above its original value if any of the foods so far de- 

 scribe(i were used, that is, there was only repair, no real growth. 

 Mice one-half or one-third grown were stunted in a most strik- 

 ing manner by gliadin foods. In three months the body weight 

 of some of them did not vary more than one gram from the mekn ; 

 in several cases the curve of growth might almost have been 

 drawn from start to finish as a straight line. But through these 

 long periods, the growth impulse was merely held in abeyance; 

 and even after three to four months, suitable food induced a gain 

 more rapid than normal, as the organism apparently tried to 

 make up for the delay. Chart 4 shows the variation during 125 

 days in the weights of three small mice, two fed on casein and 

 one on gliadin food; and shows also the tremendous gains made 

 immediately after changing to a mixed diet. In two days the 

 mouse fed on gliadin, represented in the chart, when supplied 

 with mixed food, gained 5 grams — 50 per cent of its weight! 

 This was the more remarkable as the stunting had continued 

 100 days, making the mouse at the end of that time nineteen 

 weeks old, six weeks past the age when the control animals on 

 mixed food had practically stopped growing. (The controls 

 weighed 28 grams twelve weeks after birth. Some of them 

 stopped growing then; some reached 30 grams during the next 

 two to three months). The casein-fed mouse whose record is 

 given in the lower curve of chart 4 showed almost as rapid growth 

 after 120 days stunting, when it was more than seven weeks 

 past the age at which anything more than extremely slow growth 

 is ordinarily made, and had indeed passed the age at which any 

 of the controls showed any increase in weight whatever. Never- 

 theless on a mixed diet it gained 8 grams in the first twelve days, 

 at the end of whicft time it became pregnant and eventually 

 bore four young which were apparently normal. Evidently the 

 capacity to grow is not necessarily lost because of its suppression 

 during early life, even though the suppression continue all through 

 the time of life during which growth ordinarily occurs. 



