GROWTH AND NUTRITION 



103 



attained normal size and proportions. It should be noted, how- 

 ever, that they state that many of their attempts to induce com- 

 plete recovery from retarded growth were unsuccessful. Fur- 

 thermore, the stunting period was not initiated in any case until 

 several days after weaning. 



In this connection the work of Mendel and one of his 

 pupils 54 should be mentioned. Young mice were maintained at 

 practically constant weight 





I'O £0 30 <fd 5V b'0 DAYS 



for varying periods of time, 

 and then given a generous 

 ration. Perhaps the most 

 striking feature of their 

 work is the extremely rapid 

 gain on refeeding, much 

 more rapid than a normal 

 animal makes at any period 

 in its life. It would seem as 

 if there were a tendency for 

 the mouse underfed for 

 twenty-seven days to grow 

 more slowly, and perhaps it 

 would never attain normal 

 weight. As regards the food 

 consumption the most strik- 

 ing feature is the indication that animals have some capacity of 

 adjusting themselves to a decreased food intake. Thus as time 

 went on the quantity of food required to maintain constant 

 weight declined. Or if animals were held at constant weight for 

 a time, they would again gain in weight, if the food supply 

 were not decreased. 



In connection with the problem of stunting, one point is of 

 interest. When growth is retarded, does it mean that all other 

 phenomena, those we denote as senescence, are retarded also, or 

 do those phenomena proceed at a normal, or only slightly re- 

 tarded, rate? In other words, does retarded growth mean that 



Figure 57. Retarded growth due to underfeed- 

 ing may be followed by very rapid growth 

 on refeeding. After Thompson and Mendel. 

 By permission of the American Journal of 

 Physiology. 



