course to educated persons of the present day. But it was creditable to Aristotle to have so fully arrived at and entertained this conception, and to have set it forth in such firmly-drawn scientific outlines, Above all, it was creditable to one who, though born of the race of Esculapius (see above, p. 3), had been trained as a dialectician and an orator, and had devoted so much time and labour to the sciences connected with words and thoughts, that he should have had the force and versatility to act also as pioneer into a totally different range of inquiries, and to collect such a mass of facts wherewith to fill in his general sketch of animated nature. It is probable that at all periods of his life his studies, observations, and notes upon matters of physical and natural science, ran on side by side with his development of mental and moral philosophy. Some have thought that the period of his residence at the Court of Macedonia, when acting as tutor to Alexander, afforded him peculiar facilities, in the shape of royal menageries and hunters and fowlers under his command, for the collection of materials for his great work on animals. However this may be, there seems no sufficient reason for taking that work itself out of the list of those which were on the stocks and more or less completed during the last thirteen years of his life.
Aristotle’s biological treatises, as briefly specified above (p. 47), consist (1) of the work ‘On the Parts of Animals,’ which contains a distinction still valid in physiology between “tissues” and “organs,” or as Aristotle calls them, “homogeneous” and “unhomo-
