The subjects of the numerous memoirs that I have myself published during the last ten years upon the question are treated anew in the pages of this volume, and a resume of my researches on osmotic growth has already appeared in the _Documents du Progres_, Sept. 1909. We have thus shown that synthetic morphogenesis has already attracted the attention of a certain number of ardent investigators. Morphogeny has now its methods and its results, and physiogeny is also developing side by side with it, since function is but the result of form. The field of research is opened, and workers alone are needed in order to reap an abundant harvest. * * * * * {123} CHAPTER XI OSMOTIC GROWTH--A STUDY IN MORPHOGENESIS The phenomenon of osmotic growth has doubtless presented itself to the eyes of every chemist; but to discover a phenomenon it is not enough merely to have it under our eyes. Before Newton many a mathematician had seen a spectrum, if only in the rainbow; many an observer before Franklin had watched the lightning. To discover a phenomenon is to understand it, to give it its due interpretation, and to comprehend the importance of the role which it plays in the scheme of nature. _Osmotic Membranes._--Certain substances in concentrated solution have the property of forming osmotic membranes when they come in contact with other chemical solutions. When a soluble substance in concentrated solution is immersed in a liquid which forms with it a colloidal precipitate, its surface becomes encased in a thin layer of precipitate which gradually forms an osmotic membrane round it. An osmotic membrane is not a semi-permeable membrane, as sometimes described, _i.e._ a membrane permeable to water but impermeable to the solute. It is a membrane which opposes different resistances to the passage of water and of the various substances in solution, being very permeable to water, but much less so to the different solutes.