The crowning event in the life of Ruysch--an event which shows how wasteful many of us men are of our productive powers when we deliberately retire from all participation in active work, physical or mental, at the comparatively early age of sixty-five--occurred in 1717, when he had attained the age of seventy-nine. Peter the Great had hardly left the premises with the great collection of specimens for which he had paid such a fabulous price, when Ruysch began the making of a new collection; and at this task he worked so diligently that in less than ten years he was able to deliver to John Sobieski, King of Poland, the greater part of the new collection (for which he received the sum of 20,000 florins). Then followed a period of about three years during which he continued active work as a teacher of anatomy, death alone seeming to possess the power to arrest his extraordinary energy. Ruysch’s only published works are the following: Catalogue of the Specimens contained in his Museum, Amsterdam, 1691; and a _Thesaurus Anatomicus_, in 10 volumes, Amsterdam, 1701–1715. In reading over the account which I have given of the discoveries made in gross anatomy and in physiology during the sixteenth and seventeenth centuries, I find that I have omitted some that may just as appropriately be mentioned in this section as in that which I intend to devote to work done in the domain of minute anatomy. I shall therefore refer to them briefly now, and then pass on to the consideration of the latter branch of my subject.