30 



J. PERCY BAUMBERGER 



TABLE 9 

 Lengthening of life cycle by retarding larvae 



.^.G.^R MEDI.*. 



24 per cent yeast 



12 per cent yeast 



6 per cent yeast 



4 per cent yeast 



3 per cent yeast 



Hot aqueous extract banana \ 



Retarded on cold extract ba-l 

 nana. Accelerated on 26th f- 

 day with living yeast J 



LIFE-CYCLE IN D.\Y3 



11.32-13.32 

 11.94-13.94 

 11.41-13.41 

 13.7 -15.7 

 12.5 -14.5 

 35.25-37.25 

 26. -28.0 



38. -40.0 



same body weight bj^ underfeeding of protein or by feeding on 

 proteins lacking in the amino-acids necessary for growth. " In 

 this way the ''menopause w^as postponed long beyond the age 

 at which it usually appears." The capacity to grow after adult 

 age is not lost if the rats have been retarded ('15), since after 

 being stunted for 100 days beyond the normal growth period, 

 they may reach full size when put on an adequate diet. It 

 "appears as if the preHixiinary stunting period lengthened the 

 total span of their life" ('17). In March, 1916, these investigators 

 produced evidence from their experiments that ''after periods of 

 .suppression of growth, even without loss of body weight, growth 

 maj^ proceed at an exaggerated rate for a considerable period." 



Larvae which have been retarded in their growth by an inade- 

 quate diet and then given the proper amount of yeast food 

 develop into normal pupae and adults. The pupal period re- 

 mains the same for larvae living twenty-eight to thirty-two days 

 as for larvae that have lived five to seven days. This is shoA^Ti 

 clearly in figure 8 and table 5. Thus the total span of the hfe- 

 cj^cle could be increased from eleven daxs to forty days or more 

 by retarding the rate of larval growth. This is shown in table 

 9. 



b. Sugar requirement of adults and larvae. The preceding 

 experiments on synthetic media show that both adults and larvae 



