Figure 7: Blood melatonin levels from P-X (dotted line), P-X/E-X (dashed line) and P-X/E-X/melatonin infused (solid line) pigeons in DD sampled by venipuncture at sjx 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 on the day of sampling. The first data points (circadian time 0400) have been re-plotted at 2800. Numbers of animals are in parentheses (n). Top panel - Individual pigeon (#nbblkblu) Bottom panel - Summary graph of the average values (+ SEM).