It is probable that the two cases are only quantitatively different. In both, autodigestion of certain cell constituents and possibly of whole cells must take place in order to obtain material for the formation of the lost part of the Ascidian. If an interstitial tissue is digested it becomes a question of how much of this tissue undergoes hydrolysis. If there is little destroyed the old shape of the gills remains, if too much is digested the old gills become a shapeless mass in which a certain number of the old cells are maintained and give rise to the new animal by cell division. The material for the new organs must of course be furnished from old cells which have been digested. If regeneration takes place in pieces which take up no food the newly formed organs must originate from material absorbed from cells of the animal which are hydrolyzed and whose material serves as food for those cells which grow. Very often this process of digestion takes place without loss of the total form of the organ and is overlooked by the pure morphologists. In _Campanularia_ also the process of collapse described above is only apparent in a fraction of the cases as in Driesch’s observations on _Clavellina_.[166] It is also possible that the red and yellow entoderm cells which gather at the end where the new polyp forms furnish the material which is utilized for the process of growth of the cells from which the tentacles arise (with or without giving off specific “hormones” besides). [166] One author, Miss Thatcher, in trying to repeat these observations, did not notice the total collapse of the tissues and concluded that my observations must have been wrong. The writer is fairly certain that his observations were correct.