FACTORS INFLUENCING REGENERATION AND POLARITY DETERMINATION IN TUBULARIA CROCEA

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Abstract
Environmental factors effecting regeneration and the origin of polarity in regeneration were investigated. The experiments were performed using coenosarc fragments and stem segments of Tubularia crocea. Regeneration was inhibited when coenosarc fragments and stem segments were inserted into glass tubing. Concomitant with the inhibition, there was a measurable drop in the pH of the sea water contained in the tubing. Coenosarc fragments inserted into the tips of capillaries regenerated at the exposed surface of the fragments. The same polarization resulted in most cases, even when large oxygen bubbles were introduced into the capillaries. Coenosarc fragments placed in capillaries, failed to regenerate, when an oxygen bubble was placed on one side of the fragments and a nitrogen bubble on the other side of the fragments. When oxygen bubbles were introduced into the emptied distal portions of Tubularia stem segments, and the cut ends of the stems were ligated, only ten per cent of the stems regenerated. All of these results support the view that the effectiveness of oxygen in regeneration may be limited by the inhibitory action of accumulated acid metabolites. Acid metabolites probably cause inhibition by increasing the hydrogen ion concentration of the medium, for at the oxygen tension of normal sea water, there is a range of pH in which regeneration is retarded, and a critical pH below which regeneration will not occur.