FURTHER EXPERIMENTS ON ADVENTITIOUS REPRODUCTION AND POLARITY IN HARENACTIS

1. The pieces of the actinian, Harenactis attenuata, which form "rings" by the union of oral and aboral ends about the whole circumference, after more or less complete removal of mesenteries and mesenterial muscles, may produce new discs with radially arranged new mesenteries and tentacles and mouth-opening and esophagus. Thus far the usual number of tentacles, twenty-four, has not been attained in any case, the largest number being sixteen. Such discs with from three to eight tentacles are of frequent occurrence, but the formation of mouth and esophagus has been observed only once. After the formation of the discs they may be gradually elevated from the surface of the rings by the development of a cylindrical column beneath them.

In addition to the well-developed discs, radially as well as bilaterally symmetrical and asymmetrical tentacle groups may arise along the line of union on either side, or the tissue of both sides may take part in the formation of a single group.

2. These further experiments with rings extend and confirm the earlier work. The new outgrowths on the rings represent a more or less close approach to new individuals and involve the establishment of new polarities and symmetries. They are to be regarded as a form of reproduction related to the formation of adventitious structures in plants The localization of the outgrowths, as well as their polarity and symmetry, have no relation to the original polarity and symmetry, but are due to ocal conditions.

The results of these experiments can be more readily interpreted in accordance with the hypothesis that polarity and symmetry are essentially molar localizations or gradation of processes along an axis or axes, than with that which regards polarity and symmetry as the effect of a summation of the individual polarities and symmetries of protoplasmic particles or molecules which are definitely oriented with respect to an axis or axes.