Driesch has made use of two other descriptive terms. The word “reparation” is used to describe the development of the hydranth of tubularia. The new hydranth is formed in this case out of the old tissue at the end of the piece (Fig. 20, _A_). The change appears to be the same as that which takes place in a piece of hydra, etc. The word “reparation” does not seem to me to express very satisfactorily this sort of change, or sharply separate it from those cases in which the animal is _repaired_ by adding what has been taken away; but in this latter sense Driesch does not use the term. I have not made use of the word, in general, except as applied to Driesch’s work. Another term, “regulation,” used by Roux,[13] and also by Driesch and others, is used in a sort of physiological sense to express the _readjustments_ that take place, by means of which the typical form is realized or maintained. By inference we may extend the use of the word to include the changes that take place in the new material, that is proliferated in forms that regenerate by this method. Driesch uses this term, regulation, to include a much more general class of phenomena than those included in the term regeneration, as for instance, the regulation of metabolism and of adaptation, etc. One of the subdivisions of the term regulation is called “restitution.” This word also is used where I should prefer to use the word regeneration as a general term, and the word reorganization when reference is made to the internal changes that lead to the production of a typical form. Both Roux and Driesch also speak of “self-regulation,” by which is meant, I suppose, that the changes taking place are due to readjustments in the part itself, and are not induced by outside factors. The expression “self-regulation” is not, I think, a very happy one, since all change is ultimately dependent upon a relation between inside and outside conditions.