112 C. M. JACKSON 



quite possible that this does not entirely eliminate the shorten- 

 ing of the column. In any event, however, this is probably a 

 factor of minor importance in altering the tail-ratio during 

 inanition. 



Hatai ('08) in a series of five 'stunted' rats in which growth 

 had been retarded (but not stopped) by a diet of starch-mixtures 

 from age of 30 days up to from 127 to 215 days (the final body- 

 weight being from 70.9 to 113.7 grams) finds the average tail- 

 ratio 0.75 as compared with about 0.82 in controls. He notes 

 that : 



The most conspicuous external differences between normal and 

 stunted rats as shown by the stunted rats are in the length of the body 

 and of the tail, both of which were considerabh^ reduced with respect 

 to the body-weight. This peculiar difference, as is seen from the table, 

 holds true in every case. Further, the ratio between the length of the 

 body and that of the tail is considerably less in the stunted rats than 

 in the control rats. . . . Underfeeding therefore produces short 

 tailed individuals. 



Recently, however. Dr. Hatai (in a personal communication) 

 states that in other inanition experiments he has obtained dif- 

 ferent results, and that ''rats either grown or kept in a state of 

 chronic inanition (starch feeding, lipoid-free ration and wheat 

 embryo feeding) give a longer tail" in agreement with my results. 



Morgulis ('11) in the salamander Diemyctylus found a rela- 

 tively greater shrinkage in the tail than in the body during 

 inanition; while Harms ('09) found the converse to be true in 

 Triton. 



HEAD 



The head (table 4; fig. 3) at three weeks normally forms an 

 average of 22.5 per cent of the body, the average net body- 

 weight being 21.2 grams. In the 11 controls at three weeks, the 

 bodj^-weight (24.6 grams) is slightly higher, and the correspond- 

 ing relative head-weight, 20.6 per cent, somewhat lower. In 

 the rats held constant from the age of three weeks to the ages of 

 six and eight weeks, the average percentage of the head (21.6 

 per cent and 23.9 per cent) is higher than that of the controls. 

 But the average body-weight in these groups is lower, more 



