We have finished our long account of individual morphogenesis proper. If we look back upon the way we have traversed, and upon those topics in particular which have yielded us the most important general results, the material for the higher analysis which is to follow, it must strike us, I think, that all these results relate to regulations. In fact, it is “secondary” form-regulations, according to our terminology, that we have been studying under the names of equifinality, back-differentiation, restitution of the second order, and so on, and our harmonious-equipotential systems have figured most largely in processes of secondary form-regulations also. But even where that has not been the case, as in the analysis of the potencies of the germ in development proper, form-regulations of the other type have been our subject, regulations of the primary or immanent kind, the connection of normal morphogenetic events being regulatory in itself. It was not the phenomenon of organic regulation as such that afforded us the possibility of establishing our proof of the autonomy of morphogenesis: that possibility was afforded us by the analysis of the distribution of potencies; but upon this distribution regulation is based, and thus we may be said to have studied some types of regulation more or less indirectly when analysing potencies. It therefore seems to me that we shall have hopes of a successful issue to our inquiries, if we now, on passing to what is called the physiology of the vegetative functions, proceed to focus our attention on the concept of regulation as such. And that is what we shall do: on our way through the whole field of physiology, we shall always stop at any occurrence that has any sort of regulatory aspect, and shall always ask ourselves what this feature has to teach us. But let us first try to give a proper definition of our concept. We shall understand by “regulation” any occurrence or group of occurrences on a living organism which takes place after any disturbance of its organisation or normal functional state, and which leads to a reappearance of this organisation or this state, or at least to a certain approach thereto. Organisation is disturbed by any actual removal of parts; the functional state may be altered by any change among the parts of the organism on the one hand, by any change of the conditions of the medium on the other; for physiological functioning is in permanent interaction with the medium. It is a consequence of what we have said that any removal of parts also changes the functional state of the organism, but nevertheless organisation is more than a mere sum of reactions in functional life. All regulations of disturbances of organisation may be called *restitutions*, while to regulations of functional disturbances we shall apply the name *adaptations*. It is with *adaptations* that we have to deal in the following.