Lectures On the Physiology of Plants

in their fibrillar network. But they possess beyond this a molecular structure which cannot indeed be detected with the microscope, but which can be inferred from their properties. As a conception of this molecular structure is of some importance in assisting us rightly to comprehend many of the phenomena which we shall meet with in the study of living plants, we will enter upon a somewhat detailed consideration of it. In speaking of the properties of organised bodies the first and most conspicuous was their capacity of absorbing water, theiijower of " swelling-up" or imbibition as we termed it. When this was first observed it was thought to be peculiar to organised bodies, to bodies, that is, which had been formed by a living organism. It has been subsequently discovered, however, that bodies which had not been formed by a living organism possessed this property, such, for instance, as the acrylcolloid of Wagner and Tollens, and membranes of precipitation of cupric ferrocyanide, of ferric hydrate, etc. In order to include these bodies the meaning of the term"organised " was extended, so as to include all bodies capable of swelling-up. Now as to the explanation of this phenomenon. According to Naegeli it is the expression of the taking up of a number of particles of water between the solid particles (termed by him micella) of the organised body. That the absorption of water is not effected by capillarity is inferred from the fact that organised bodies...