THE OSPHRADIUM IS INVOLVED IN THE CONTROL OF EGG-LAYING IN THE POND SNAIL LYMNAEA-STAGNALIS

Ablation of the osphradium (a peripheral putative chemo-sensory organ) in Lymnaea stagnalis resulted in significant increase of egg-laying a ctivity as compared with control animals (observed for 50 days). Cutti ng the osphradial nerve increased egg-laying to a lesser degree and on ly for the first 15-20 days. Water changes in the aquaria had a simila r stimulating effect on egg-laying activity in both osphradium-deprive d and control snails. Permanent aeration of the aquaria abolished this effect. Possible mechanisms of tonic inhibitory action of the osphrad ium on egg-laying are discussed.