ADDITIONAL EXPERIMENTS ON THE BEHAVIOR OF BUDS IN THE ASCIDIAN,APLIDIUM MULTIPLICATUM

Abstract

In a previous paper by the authors, it was suggested that that behavior of growing buds, which form a common cloacal system, is affected by a substance which is secreted by the mother zooid and diffuses through the tunic. Four sets of experiments were made to confirm the existence of the substance, and to get more information about the attractant. In the first set, the thorax of a grown zooid was removed before budding, and artificial strobilation was induced. In this case the buds lacked the mother zooid from the first. In the second, the thorax of a grown zooid was removed before budding, together with the tunic covering the thorax. In the third, the anterior tip of a mother zooid, thought to be a center of secretion, was removed. In the fourth, the experiment was designed to show whether a bud is attracted only by its mother and sisters or also by other zooids in the same colony. After these operations the behavior of buds was followed. The results supported the existence of the attractant. They suggested that the time of secretion is not restricted to the period of budding, that the site of secretion is not restricted to a special region of the zooid, and that a bud is attracted not only by its mother but also by any other zooid in the same colony.