442 



EFFECT OF TEMPERATURE UPON FACET NUMBER 



Experiment 72 supplies the data on the length of the period at 

 15° (Table XVIII and Fig. 14). As pointed out for Experiment 59 

 there may be a shght difference in the rates of the individual bottles. 

 Experiments 62 and 72 show such a variation. In Experiment 62, the 

 period was initiated on the 8th day. In Experiment 72, only two 



TABLE XVIII. 



Experiment 72, Showing the Distribution of Facet Numbers. Larva Were Allowed 



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



for the Remainder. 



* All these cultures were at 27° for the first 24 hrs. They were then removed 

 to 15° for the number of days indicated at the top of the table and allowed to 

 complete development at 27°. 



individuals had passed the effective period at 15° when the transfer 

 was made from 15 to 27°. After 9, 10, and 11 days an increasing num- 

 ber of individuals show the 15° count, and after 12 days only five 

 of 94 individuals had not completed the facet number-determining, 

 reaction when the transfer was made. 



