Experimental control of polarity in corymorpha palma.

Abstract

Corymorpha palma is a large, unbranched tubularian hydroid abundant on the Southern California coast. Many different lines of evidence show that in this form, as in others, the physiological axis is primarily represented by a quantitative differential, a gradient, in metabolic activity and associated conditions in the protoplasm. From the most active or 'high' end of this gradient the apical structure, the hydranth, develops and from lower levels the stem and base.

The forms resulting from the reconstitution of isolated pieces of the stem of Corymorpha differ with length of piece, level of body, physiological age and condition of animal, etc., and also with differences in various external conditions. The forms produced fall into three chief groups: (1) uniaxiate, a single individual or an apical part, which may develop from either distal or proximal end of the piece, or under certain conditions, from the side; (2) biaxiate, with an apical end developing from each cut surface and other parts in order from each apical end, as far as the length of the piece permits; (3) intermediate forms, biaxiate as regards the apical ends, but with one or more proximal or basal regions developing from the side of the stem between the two apical regions. In lots of similar pieces from similar stems the frequency of uniaxiate and intermediate forms is much higher in pieces allowed to lie undisturbed on the bottom of the container than in pieces supported above the bottom on loose absorbent cotton. The frequency of uniaxiate and intermediate forms is higher in pieces undisturbed on the bottom than in pieces moved about and turned over every few hours. Pieces above a certain length lying on the bottom and subjected to the action of depressing agents, e. g., alcohol, LiCl, chloretone, ethyl urethane, give a higher frequency of uniaxiate and intermediate forms and in such forms a higher frequency of large proximal parts and multiple basal ends, than pieces in well aerated water.