We report here the presence of a bioactive compound in the secretion o
f the accessory salivary glands (ASGs) of Nucella lapillus. We have pu
rified the compound using HPLC and identified it as serotonin by mass
spectrometry, UV spectroscopy, HPLC and capillary electrophoresis. Ser
otonin was not found in the secretions of the acinous salivary glands
or the hypobranchial gland. The amount of serotonin in the secretion o
f the ASGs does not show seasonal or regional variation.