Hormonal control of reproduction in Busycon: laying of egg capsules caused by nervous system extracts

Mature specimens of female Busycon laid egg capsules when injected with extracts of nervous systems of male or female Busycon. The substance causing this behavior, named egg capsule laying substance (ECLS), was found most reliably in parietal ganglia, less consistently in cerebral-pleural ganglia, and rarely in other ganglia. Both species of Busycon found in Woods Hole, B. canaliculatum and B. carica, contained ECLS, and ECLS of each species was active in the other. ECLS activity was not destroyed by boiling for up to fifteen minutes. Centrifugation of nervous system extracts at 105,000 X g yielded ECLS only in the pellet. ECLS was not released from the pellet by freeze-thawing or by 1.0 M NaCl, but could be partially solubilized by boiling extracts before centrifugation. ECLS activity was destroyed by protease. Several animals "spontaneously" laid strings of egg capsules after being put in a group tank with males and other females. Approximately the first ten capsules laid by these animals were devoid of eggs, after which egg-containing capsules were laid. Injection of ECLS into a spontaneous egg layer within a few hours after cessation of spontaneous egg laying caused the laying of capsules containing eggs. The possibility that ECLS may normally be responsible for the laying of both eggs and egg capsules is discussed.