ULTIMATE EFFECTS OF INANITION ON SIZE 109 



the ultimate body weight of the refed survivors being more than 

 one-third below that of the normal controls. 



This result is in general agreement with Aron ('14), who 

 found that if the underfeeding of young rats is prolonged beyond 

 50 to 150 days, the rats upon full refeeding fail to reach their 

 normal size and weight, thus remaining permanently stunted 

 or dwarfed. Aron therefore concluded that full recovery upon 

 refeeding is possible only when the retardation of the growth 

 has not extended beyond, the time of the normal active growth 

 period. 



Briining ('14) found that young nursing rats underfed by 

 removal from the mother for successive periods are greatly 

 retarded in later growth. The normal body weight was not 

 fully recovered upon subsequent full feeding, but the experi- 

 ment was not continued long enough to determine whether the 

 effect was permanent. 



Hatai ('07), however, observed complete recovery of normal 

 body weight on refeeding after partial starvation (starch diet) 

 for three weeks in rats one month old. Stewart ('16) also 

 obtained similar results in rats refed after maintenance (constant 

 body weight) by underfeeding from three to ten weeks of age. 



Osborne and Mendel ('14, '15), in an extensive series of experi- 

 ments upon the growth of rats with various inadequate protein 

 diets, likewise found a remarkable capacity for full recovery of 

 body weight upon proper refeeding, even after growth has 

 been suppressed for periods of time (up to 558 days) far beyond 

 the normal growth period. They claim that the capacity to 

 resume growth does not depend upon the size or age at which 

 the inhibition of growth is effected, and state that: "It is now 

 reasonable to ask whether the capacity to grow can ever be lost 

 unless it is exercised." A considerable number of cases, with 

 growth curves, are presented to support this conclusion. These 

 are chiefly rats in which growth was retarded by qualitatively 

 deficient (inadequate protein) diets, which will be discussed 

 later. In one case, however, a female rat in which growth 

 was repressed by 'limited quantity of food' (no further details 

 given), the body weight of 53 grams at 39 days of age reached 



