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FREDERICK RUYSCH. 



1638-1731. 



THE Hague was his birthplace, and there he set up as an 

 apothecary, going to Leyden to study under Sylvius and 

 van Home, where he graduated as M.D. in 1664. He was 

 a lecturer on anatomy, taught midwifery and botany. He was, how- 

 ever, essentially an anatomist, famous for his anatomical injections — 

 we still use the term tunica Ruyschiana — an art which it is said he 

 learned from Swammerdam. His works abound in plates with 

 objects fantastically grouped. In 1717 his great anatomical collection 

 was sold to Czar Peter for 30,000 florins, but only part thereof, it is 

 said, reached St. Petersburg, as the sailors drank the spirits. Another 

 collection was sold to Sobieski, of Poland, who presented it to the 

 University of Wittenberg, so famous in the story of Luther and the 

 Reformation. 



A. VAN LEEUWENHOEK. 



1632-1723 (act. 91). 



BORN at Delft, Leeuwenhoek spent his early years in a linen 

 draper's establishment ; at the age of twenty-two he received a 

 sinecure office in his native town. An indefatigable worker, 

 most diligent and supremely conscientious, he applied his energy to 

 the investigation of the minute structure of practically everything he 

 could lay his hands on. He made his own lenses. R. de Graaf in 

 1673 sent his first communication to the Royal Society, to which he 

 communicated paper after paper. He was the first to carefully describe 

 the red blood corpuscles ; he confirmed the observation of Malpighi on 

 the capillaries (1688) ; he described and figured the spermatozoa of the 

 dog and other animals ; he showed the difference in structure between 

 the stems of monocotyledons and dicotyledons, the crystalline forms of 

 various salts ; he described infusoria in 1675, and rotifers, the bacteria 

 as we now know them, or animalcules that he found in his own mouth, 

 the stucture of teeth, crystalline lens, &c. His Opera omnia seu 

 Arcana natures were published at Leyden in 1792, and an English 

 translation by S. Hoole in 1798-1800. His observations were all 

 made with the simple microscope. He made his own, and had several 

 hundreds of them. Each consisted of a small biconvex lens, placed 

 in a socket between two plates of brass, which were riveted together 

 and pierced with a small hole opposite the lens. The object to be 

 examined was fixed at a convenient distance and its focal distance 

 adjusted by screws. 



K 



