242 BESSIE NOTES 



experiment, and all organisms after the fifth generation were 

 kept in an electric constant temperature oven at 23° to 25°C. 

 Since egg production and length of life are correlated as indicated 

 above, the number of eggs produced rather than the length of 

 life was decided upon as a more reliable measure of performance, 

 and an attempt was made by selecting in each generation the 

 individual producing the highest number of eggs to increase the 

 maximum number of eggs produced by any individual beyond 

 thirty, a number frequently obtained in individuals chosen at 

 random. 



The progenitor for this selection work was chosen at random 

 from the progeny of a mother producing twenty-four eggs. The 

 individual thus chosen produced twenty-seven eggs, designated 

 as the first generation. All these eggs hatched, but two of the 

 young organisms died before producing eggs. The minimum 

 number of eggs produced by any of the twenty-five sister indi- 

 viduals in the first generation was 5, the maximum 28, the 

 average 18.68. 



A check-line was reared under the same experimental condi- 

 tions and isolations made at the same time as in the selection 

 experiment, but the progenitor for the next generation was 

 chosen at random rather than by an inspection of the egg-deposit- 

 ing record. In the first generation the check-line deposited 18 

 eggs, a number slightly below the average, 18.68, for the selec- 

 tion line. The individual range for the length of life in the 

 selection experiment was two to six days with an average of 4.36 

 days as compared with an length of life of four days in the check. 

 During the first generation the selected line showed a much 

 higher maximum and average number of eggs, and a greater 

 average length of life than the non-selected line. 



The further course of the experiment, through fifteen genera- 

 tions of selection, is shown in table 3. Throughout the experi- 

 ment the individual producing the highest number of eggs was 

 chosen to continue the selected lines, while for the control line 

 an individual was taken at random. 



As will be seen in table 3, fifteen generations of selection of the 

 individual producing the highest number of eggs did not bring 



