THE LIFE OF THE WRITER.

...and to examine the small creatures that fly by day and night, in Gelderland, in the district of Utrecht, and in Holland. He searched the air, water, earth, land, fields, meadows, cultivated areas, wilderness, dunes, riverbanks, shores, rivers, stagnant water, lakes, the sea, wells, herbs, piles of rubble, holes, inhabited places, and yes, even private chambers, so that he might search for the eggs, worms, nymphs, and butterflies, and learn their nests, food, way of life, diseases, transformations, and gatherings. And truly, in his early youth, he discovered more certain and true things in all this than the known writers of all the centuries together. I am recounting something unbelievable, yet very true: at least, that is how the competent judges in these matters have judged.

Thus instructed, he came to live in Leiden in the year 1661, to attend the Academy of Holland. On the eleventh of October, he was registered in the civic role of Academy members, and for two full years he listened to the most famous Mr. Jan van Horne, who taught the anatomy of the human body and practical surgery. He also attended very closely to the teachings of Franciscus de le Boe Sylvius to learn the art of medicine. In this, he progressed so that, according to the law, having been well examined, on the 11th of October 1663, he was accepted onto the list of Candidates of Medicine at this Academy. During this entire time, he formed a special friendship with Nicolaus Steno, that great artist in anatomy, and he maintained this relationship with him until his death. He also became a friend here to Rynier de Graaf, likewise an excellent practitioner of anatomy, though this later broke out into bitter hatred due to envy. The taste for this science then so gripped his spirit that he seemed to have been born solely for it. His progress was incredibly fast, which made him happy to begin considering how he might preserve in an uncorrupted state the parts of corpses he had prepared by dissection, for lasting ability in demonstration. He sought advice on staying the labor of constantly having to repeat the work; and to avoid the harmful disgust of corpses that rot so quickly; and also to prevent the difficulty of frequently obtaining bodies of those recently deceased. He succeeded in this, having previously found the finest techniques in handling small creatures. It happened that he satisfied the most famous Sylvius in this, who at that time had hardly anyone equal to him in the work of anatomy. Nothing pleased that gentleman more than when he dissected frogs for him in the most artistic way. It was already on the 15th of January 1663 that he showed how the air, upon inhalation, could be brought from the windpipes into the artery and vein of the lung, and through that path, into both ventricles of the heart. See Sylvius, Medical Disputations, 7, § 79-88.

After that, he traveled to France and lived for some time at Saumur, at the house of Mr. Tanaquil Faber, where he made many observations on the small creatures. On the 19th of June, he discovered there, with the help of very thin tubes, the valves in the water vessels. He drew them with his own hands and sent them on the 28th of June to Steno, who was then present in Copenhagen,