GROWTH REGULATING SUBSTANCES IN ECHINODERM LARVÆ

Abstract

The eggs and larvae of the sea urchin and starfish contain growth regulating substances, which pass out into the surrounding water during segmentation and the later stages of larval development. There is some evidence that the inhibiting substances are associated with the lipid constituents, and the accelerating factor is contained in the protein molecule. After the removal of the fats from the extracts of gastrulae and plutei, a solution of the residue in sea water exerts a slightly stimulating effect on growth; when the alcoholic extracts are filtered, and the precipitate removed the nitrate has the same accelerating effect. Acetone extracts of eggs and of larvae, as well as alcoholic extracts, if used in pure form, have an inhibiting influence. The retarding effect of secretions of growing embryos is removed in the presence of animal charcoal and fuller''s earth. The percentage of normal larvae resulting from eggs grown in the presence of these adsorbents is greatly increased while mortality is decreased.