the Parts of Animals,’ as containing general principles of anatomy and physiology. Next it seems probable that the work ‘On the Soul’ was produced, which was a physiological account of the vital principle as manifested in plants, animals, and men. A set of Appendices, as we should now call them, on various functions connected with life in general, such as sensation, memory, sleep, dreaming, longevity, death, &c., were added by Aristotle to his work ‘On the Soul.’ Afterwards, the ten books of ‘Researches on Animals,’ and the five books ‘On the Generation of Animals,’ together with a minor treatise ‘On the Progression of Animals,’ and with a collection of ‘Problems,’ which Aristotle probably kept by him, and added to from time to time, made up the series of his physical and physiological writings, so far as he lived to complete them. Treatises ‘On the Physiology of Plants,’ and ‘On Health and Disease,’ had been promised by him, but were never achieved. Simultaneously with some of the works now mentioned, but in idea last of his writings, and intended to be the crown of them all, the ‘Metaphysics’ were probably in course of composition when the death of Aristotle occurred.
It has been generally fancied that Aristotle was a very voluminous writer, and Diogenes Laertius, in transcribing the ‘Alexandrian Catalogue,’ remarks of him that “he wrote exceedingly many books.” We, however, have no reason for joining in this opinion. His genuine works that have come down to us, fill altogether less than 3000 pages, and this amount in mere point of quantity is not anything unusual or sur-
