We had best therefore begin our discussions with a recapitulation of our problem. We are studying adaptations in functioning--that means we want to know how the organism behaves with regard to any change which may take place in its functional state. We apply the term regulation, or in particular adaptation, to any kind of reaction on the part of the organism which re-establishes the normal state of functioning, and we now want to learn to what degree such adaptations exist in the field of physiology. SPECIFIC ADAPTEDNESS *NOT* “ADAPTATION” It is important to keep well in mind our strictly formulated theme, as by doing so we shall be able to exclude at once from our materials a large group of phenomena which occasionally have been called regulations by physiological authors, but which, in fact, are not of the adaptation type and therefore cannot be said to afford those problems which possibly might have been expected. Typical peculiarities in functional life cannot be called “regulations” for this very reason. If, for instance, the organism selects specific amounts of specific kinds of organic food or of salts out of the combinations of salts or organic food normally offered to it in the medium, as indeed is most typically shown for instance by the roots of plants, there cannot be said to occur a “regulation” or “adaptation” with regard to the permeability of the cell, nor is it strictly a case of “regulation,” if so-called selective qualities are discovered in the processes of secretion, say of the epithelium of the kidney. All these facts are typical and specific peculiarities in functioning which are duly to be expected, where a very typical and specific organisation of the most elaborated kind exists. Indeed, after studying such an organisation we must not be astonished that functions in organisms follow lines which certainly they would not have taken without it. Take the fact which is quoted very often, that the migration of compounds or of ions in the organisms can happen quite contrary to all the laws of osmosis, from the less concentrated to the more concentrated side of a so-called “membrane.” There *is* no simple “membrane” in the organism, but a complicated organisation of an almost unknown character takes its place, and nothing, indeed, is against the assumption that this organisation may include factors which actually drive ions or compounds to the side of higher concentration, which indeed drive them by “doing work,” if we like to speak in terms of energy; and these factors included in organisation may very well be of a true physical or chemical nature.[90] [90] According to investigations of the last two years, the physics of colloids seems to play as important a part in physiology as osmosis does; we here meet “means” of functioning just as we have already had “means” of organogenesis.