30 The Harveian Oration.
belief as that which is daily presented to us in the development of the ovum ? From a cell so simple that our minds are baffled by its simplicity in attaching any significance to it whatever, the whole complex organism grows into form and activity. Is it not therefore conceivable, is it not rather by this example suggested, that the higher organic forms which inhabit the world to- day may, by the keen eye of science, be tracked through the dim vista of past time to their equally simple beginnings, varied and modified by the changing circumstances in and around them? Simplicity, as we have proof in these early conditions of the ovum, raises of itself no objections. It is imposed upon the highest as well as on the lowest organisms to have the same homo- geneous beginnings; and if, as a modern physiologist says, "a single cell, under appropriate conditions, becomes a man in the space of a few years, there can surely be no difficulty in understanding
- Herbert Spencer, "Principles of Biology," vol.i.
p. 350.
