place, nor when and where dilatation and contraction occurred, by reason of the ra- pidity of the motion, which in many animals is accomplished in the twinkling of an eye, coming and going like a flash of lightning: so that the systole presented itself to me now from this point, now from that; the diastole the same; and then everything was reversed, the motions occurring, as it seemed, variously and confusedly together. My mind was, therefore, greatly unsettled; nor did I know what I should myself con- clude, nor what believe from others." Yet if Harvey's immortal labours overcame the apparently superhuman difficulties of the cir- culation, who can doubt that some kindred genius shall hereafter lay open before us the springs of development (evolution). That this will be done cannot be doubted; for who can draw a limit either in nature or in the understanding, after contemplating the greatness of results, and the simplicity of the factors presented to us in the history of generation? Prior to experience, what could have made such demands upon our
