IX — Studies in tunicate development Part IV—Asexual reproduction

Abstract

Budding in Tunicates has long been a subject of considerable interest and controversy. The earlier investigations were concerned for the most part with the morphology of the budding processes, and many classifications based on the nature of the organs and tissues were evolved. More recently the emphasis, as represented by the series of papers by Brien, has been applied to the more fundamental problems of morphogenesis. The point of view of the present paper lies between the two just mentioned. The general biology of asexual reproduction has been studied throughout a much wider range of animals than in previous accounts, while in addition the nature and nutrition of the tissues of the bud have been investigated in each case but without analysis of the process by which the undifferentiated bud tissue develops the organization of the adult. Before any general discussion is attempted, a description of asexual reproduction will be given for each tunicate genus with that faculty. In each there is a concentration on three questions, the internal or external factors that induce this method of reproduction, the process by which the actual or physiological isolation of the parts from the whole is accomplished, and the nature of the tissues so isolated.