Page:The Harveian oration - delivered at the Royal College of Physicians, London, June 29th, 1867 (IA b22315263).pdf/25

Rh gress, through which much new light may be hoped to be arrived at. Numerous lately ascertained facts point to the probability that a force is set up in the union or proximity of different membranes and fluids, resembling that which is admitted to take place in different metals under varying temperatures; and that this force may be the means of inducing what we call absorption and secretion. The very absorption of particular gases by metals and other substances, in the way of “occlusion” (to which I just now referred), seems to point to the existence of a certain elective power independent of a living principle. We may be asked, What is this but a further exemplification of chemical action? And as yet we are not in a position to give a definitive answer. But it is at least a field of inquiry which we welcome as new and very hopeful.

When we see a bit of leaf broken off, as we may in the plant Vallisneria spiralis, and are able to witness the movements of fluids within the minute cells following a precise and continuous course for hours after separation from the parent stem, all going on with-