motion as different things; and motion as a super- added quality. In denying the older opinion' that the heart is the source of motion, of perfection² and of heat, he put the difficulty but one stage back; and, when in the treatise on Generation he pro- pounded his transcendental notion of the impreg-
and Virchow, it would ill become me to depreciate a distin- guished Fellow of my own College, and as a clinical observer Glisson had considerable merits; but as a physiologist he wAS sunk in realism. He was happy in the invention of the technical term "irritability," but for him this virtue was as metaphysical an essence as the vital spirit; his prime motor was not physical. As a philosopher I fear the inde- pendent reader of his works will find him fanciful and wearisome. Herein Ilarvey's sagacity brought him towards the truth. "Air," he says in the De generatione, "is given neither for the cooling nor the nutrition of animals......it is as if heat were rather enkindled within the foctus (at birth) than re- pressed by the influence of the air." Boyle (who says that he worked under the influence of Harvey's discoveries) carried this matter forward by most interesting and sagacious experi- ments with his air-pump. For the layman, I may add that (to speak generally) before Harvey's time respiration was regarded not as a means of combustion but of refrigeration. How man became such a fiery dragon was the puzzle! 2 Perfection was attributed, not only by medieval philo- sophers but also by Plate and Aristotle, to the circle. Cir- cular movement was therefore the most perfect, and therefore again must be that of the planets. This is a good illustration of the almost necessary tendency in the earlier excursions of thought to equate incoordinates, and to fill gaps in reason- ing from alien sources.
