ULTIMATE EFFECTS OF INANITION ON SIZE 99 



in division A were underfed by removal from the nursing mother 

 at successive intervals, as described by Stewart ('18). In 

 eight litters, the test rats, which weighed about 5 grams at 

 birth, were retarded so as to reach only about 10 or 12 grams 

 (the normal being 20 to 25 grams) at three weeks of age. After 

 this they were fully fed, as were the controls throughout. They 

 received (after the weaning period) an abundant diet of whole 

 wheat (Graham) bread soaked in whole milk. Water from the 

 city supply (Mississippi River) was given ad libitum through- 

 out. In one litter (no. 86) the underfeeding was similarly 

 prolonged from birth to four weeks of age, in three litters to 

 six weeks, and in nine litters to about ten weeks (the extreme 

 for this group being eighty-three days). The underfed rats 

 at ten weeks (beginning of refeeding) had reached only about 

 15 or 16 grams in body weight, the normal at that age being 

 over 100 grams. 



In division B, the underfeeding did not begin until the age 

 of three weeks (the weaning period), at a body weight of 20 to 

 25 grams. In one litter (no. 33) the test rats were refed at 

 twenty weeks (138 days), the body weights then being 33 to 

 43 grams. - In the remaining sixteen litters, the underfeeding 

 was prolonged to nearly a year of age, the average being 342 

 days (range 235 to 375 days). The body weights of the test 

 rats at this time (beginning of refeeding) averaged about 60 

 grams, while the normal controls had reached their maximum 

 adult size (about 200 grams in the females and 250 grams in 

 the males). 



The curves of the average body weights in the various test 

 and control groups (sexes separately) are shown in charts 1 to 

 5. The composite curves were constructed from the average 

 body weights for the individuals of each group at corresponding 

 ages, excepting in the refed rats. Since the test rats in each 

 group were not all refed beginning at the same age, the average 

 date of the beginning of refeeding in each group was taken as 

 the starting point for the refed animals, and their body weights 

 arranged and averaged according to the number of days of 

 refeeding in each case. 



