Figure 4: Blood melatonin levels in intact (solid line), P-X (dashed line), and P-X/melatonin infused (dotted line) pigeons sampled by venipuncture in DD at six hour intervals for 24 hours. P-X/infused pigeons whose blood melatonin levels of samples are shown here received 0.93 ug melatonin/hr for 10 hours (approximate circadian time 1900 - 2900) on the day of sampling. The 0400 data points have been double plotted at circadian time 2800. Top panel Individual pigeon (#20) Bottom panel - Summary graph of the average values (+ SEM); intact, n=20; P-x, n=28; P-X/melatonin infused, n=11.