[55] For a good discussion of “super-regeneration” in the roots of plants see Němec, *Studien über die Regeneration*, Berlin, 1905. Goebel and Winkler have succeeded in provoking the “restitution” of parts which were not removed at all by simply stopping their functions (leaves of certain plants were covered with plaster, etc.). (*Biol. Centralbl.* 22, 1902, p. 385; *Ber. Bot. Ges.* 20, 1902, p. 81.) A fine experiment is due to Miehe. The alga *Cladophora* was subjected to “plasmolysis,” each cell then formed a new membrane of its own around the smaller volume of its protoplasm; after that the plants were brought back to a medium of normal osmotic pressure, and then each single cell grew up into a little plant (all of them being of the same polarity!). Two questions seem to be answered by this fact: loss of communication is of fundamental importance to restitution, and the removal of mechanical obstacles plays no part in it, for the mechanical resistances were the same at the end of the experiment as they had been at the beginning. (*Ber. Bot. Ges.* 23, 1905, p. 257.) For fuller analysis of all the problems of this chapter see my Organische Regulationen, my reviews in the *Ergebnisse der Anatomie und Entwickelungsgeschichte*, vols. viii. xi. xiv., and my Boston address mentioned above. Compare also Fitting, *Ergebn. d. Physiol.* vols. iv. and v. [56] The so-called “inner secretion” in physiology proper would offer a certain analogy to the facts assumed by such an hypothesis. Compare the excellent summary given by E. Starling at the seventy-eighth meeting of the German “Naturforscherversammlung,” Stuttgart, 1906. But I see quite well that such a theory is very little satisfactory; for what has to be done in restitution in each case is not a simple homogeneous act, for which one special material might account, but is a very complicated work in itself. It was the defect of the theory of “organ-forming substances” as advocated by Sachs, that it overlooked this point. So all we know about the proper stimuli of restitutions is far from resting on any valid grounds at all; let us not forget that we are here on the uncertain ground of what may be called the newest and most up-to-date branch of the physiology of form. No doubt, there will be something discovered some day, and the idea of the “whole” in organisation will probably play some part in it. But in what manner that will happen we are quite unable to predict. This is the first time that, hypothetically at least, the idea of the whole has entered into our discussion. The same idea may be said to have entered it already in a more implicit form in the statement of the threefold harmony in ontogeny.