122 



5. It seems not improbable that the length of life and the coming to 

 maturity of the germ cells may be in some way physiologically connected. 



6. The low productivity of the Truncate skips a generation when 

 crossed to a high-producing strain and rea]iiiears in the Fo generation. Jt 

 is difficult to correlate tlie length of life in these strains with the number 

 of offspring pro<:luced, because it is evident from my other studies that 

 the fertilizing power of the gametes as well as egg production are involved 

 as variable factors in iiroductivity. 



