440 



EFFECT OF TEMPERATURE UPON FACET NUMBER 



for 24 hours. The parents were then removed to the next set of 

 bottles, while the bottles containing the eggs and larvae were trans- 

 ferred to 15°. Here they were left for the number of days indicated 

 in Table XVII and then returned to 27° to complete development. 



TABLE XVII. 



Experiment 62, Showing Distribution of Facet Numbers. Larva Were Allowed to 



Complete Part of Development at 15° and Were then Transferred to 27° 



for Remainder. 



* The bottles were at 27° the first 24 hrs.; then removed to 15° for the number 

 of days indicated before return to 27°. Parents are the same as in Experiment 59. 



It is plainly evident that the effective period is not initiated at the 

 end of 3 days as at 27°. The point X is not reached even at the 

 end of 7 days at 15° plus the 1st day at 27°. In Experiment 62, 

 the change comes on the 8th day at 15° (Fig. 13). Unfortunately 

 this experiment was not planned to cover a longer period; a second 

 experiment was therefore started. 



