Comparison of peak phases for wings vs. heads. tim-luc transgenic specimens were monitored for luminescence fluctuations in 12-h:12:-LD cycles. Labeling conventions are as in Figure 11c. Here, a 3.4-hour difference between the peak times for the wing (*) vs. head timecourses is indicated by the vector for the former data pointing to -0.3 and that for the head pointing to 3.1. This difference was found to be significant (F statistic, p < 0.01) by the Watson-Williams-Stevens test (see text).