THE LIFE OF THE AUTHOR.

He examined and captured small animals, both flying by day and by night. He scrutinized the air, waters, lands, fields, meadows, cultivated and uncultivated ground, sandy hills, riverbanks, shores, rivers, ponds, wells, lakes, seas, trees, plants, ruins, caves, inhabited places, and latrines, in order to track eggs, worms, nymphs, and butterflies, and to learn their nests, food, habits, diseases, transformations, and pairings. And truly, even in his early youth, he discovered more certain and true things about these than the known authors of all the centuries put together. I speak of something incredible, yet most true: thus have the competent judges of these matters decided.

Thus instructed, he came to Leiden in the year 1661, for the sake of attending the Batavian Academy, and there, on the eleventh of October, he was inscribed in the register of Academic citizens. For two full years, he applied himself diligently to the work of the most famous man, Joannes van Horne John van Horne, who taught surgery. He attended the lectures of Franciscus Sylvius de le Boe most diligently, in order to learn medicine from him. The progress of these studies was such that, on the eleventh of October, 1663, having been examined according to the laws, he was legitimately inserted into the register of Candidates of Medical Art at this Academy. During this whole time, he formed a friendship with Nicolaus Steno, that great anatomist, which he maintained intact with him until his death. He also cultivated a friendship here with Regnier de Graaf, truly a distinguished follower of anatomy: but this later turned into bitter hatred, out of envy. The sweetness of anatomical science then enticed his genius, which seemed born solely for these sacred things. Joyful at his very rapid progress in these areas, beyond all belief, he began to deliberate how he might preserve the parts of the body, prepared by dissection, for the eternal use of anatomical demonstration: so that he might be relieved from the labor of always repeating the work; so that he might be free from the harmful disgust of immediately rotting corpses; and so that he might assist the difficulty of frequently obtaining the bodies of the recently dead. He was successful in this, having long since discovered subtle techniques in treating insects. It happened that he proved himself skilled in these matters to the most famous Sylvius, than whom hardly anyone, at that time, was more industrious in anatomical matters. In no thing, however, did he please him so much as when he dissected frogs before him most skillfully: on the fifteenth of January of this very year, he had shown him an experiment by which he demonstrated that air in inspiration could be led from the bronchi into the artery and vein of the lung, and thence toward both chambers of the heart. See Sylvius, Medical Disputations, VII, § LXXIX-LXXXVIII.

Having departed after this for the French lands, he lived for some time at Saumur, in the house of Tanaquil Faber; where he instituted various observations on insects. And there, on the nineteenth of June, in the year sixty-four, he discovered valves in the lymphatic vessels, with the help of very thin tubes. Having depicted these with his own hand, he sent them on the twenty-eighth of June to Steno, assuming him to be at Copenhagen—