612 PHOTOPERIODISM IN INVERTEBRATES 



8 days after groups had been changed from an inductive to a non- 

 inductive regime. Apparently, however, the effect of inductive day 

 lengths may carry over a much longer period than this, for when 

 collections were brought into the laboratory from nature during the 

 summer, pupations occurred for several weeks in spite of the short 

 day on which they were placed. 



Experiment 10 tested the effectiveness of the alternation of various 

 combinations of long day, inductive cycles (13Vi-hr photoperiods) 

 with short-day, noninductive cycles (11-hr photoperiods). The larvae 

 used were collected in North Carolina on December 26, 1955, and 

 the experiment began January 19, 1956. Experimental group A was 

 given a treatment of consecutive long days, group B received a long 

 day alternated with one short day, group C a long day alternated with 

 two consecutive short days, group D a long day alternated with three 

 consecutive short days, and group E a long day alternated with four 

 consecutive short days. After 42 days 65% of group A had pupated, 

 and no pupations had occurred in any of the other groups. At this 

 time the larvae in groups C, D, and E, apparently still in diapause, 

 were placed under different experimental conditions. One dish of 

 larvae from group C and one from group E were used to make up 

 group F, which was placed on a regime of one short day alternated 

 with two consecutive long days. The two dishes from group D were 

 used for group G, which received one short day alternated with three 

 consecutive long days. Finally, the remaining dishes from groups C 

 and E (one from each) were used to make up group H, which was 

 given one short day alternated with four consecutive long days. 

 Results after 72 days under these regimes are given in Table V; also 



Table V. Experiment 10, Results after 72 Days 



° L, long day; S, short day. 



