THE EFFECT OF THE REMOVAL OF PERISARC ON REGENERATION IN TUBULARIA CROCEA

¹ From the Department of Zoölogy, Columbia University and the Marine Biological Laboratory, Woods Hole, Mass.

1. Experiments in which lateral regions of the coenosarc of Tubularia were exposed indicate that the rate of regeneration in such regions is proportional to the area exposed to the influence of freely circulating sea water.

2. The morphology and polarity of central regenerants in thicker stems varies with the area exposed. Forms ranging from single complete hydranths, whose polarity was at right angles to the original polarity, to two hydranths, fused to a greater or lesser extent, were obtained. The polarity of the double hydranths varied with the degree of fusion. All angles to the original polarity were obtained.

3. Injury to the exposed coenosarc is not a factor in the present cases.

4. The ends of a stem exert a definite dominance over the exposed central regions. This dominance may be removed by ligaturing the ends. When this is done the rate of regeneration of the central region increases greatly.

5. A more distally placed central exposed region inhibits another exposed region placed more proximally on the same stem.

6. It is suggested that the probable stimulator of regeneration in Tubularia is the oxygen in the sea water. The results on rate of regeneration and on morphological and polarity variations may be explained by the amount of oxygen available to the coenosarc when areas of different size are exposed.