SWAMMERDAM 175 



Eegner de Graaf (Graaf of the Graafian follicles) was 

 another friend „ of Swammerdam's student days, but 

 rivalry embittered their relations before Graafs early 

 death. Stensen, Graaf, and Swammerdam were all 

 pupils ofPranciscus Sylvius (Fran9ois de la Boe), who 

 professed medicine at Leyden with great distinction 

 from 1658 until his death in 1672. This Sylvius (who 

 must not be confounded with the anatomist, Jacobus 

 Sylvius, who taught Vesalius) was a zealous and skilful 

 anatomist ; he was also one of the best chemists of that 

 early time. To carry on his studies and enlarge his 

 experience, Swammerdam next travelled, as was the 

 rule with young students of adequate means. Perhaps 

 it was the existence of a o^reat Protestant college ^ 

 which directed his course to Saumur (1663), where he 

 carried on his insect studies. Here, in the year 1664, 

 he discovered the valves of the lymphatic vessels, and 

 sent an account of them with drawings to his friend 

 Stensen. Not long after Kuysch announced the very 

 same discovery, and Swammerdam was inclined to 

 believe that his drawings had been shown to Ruysch. 

 Visiting Paris, Swammerdam became acquainted with 

 Melchisedec Thevenot, traveller, French ambassador 

 at Genoa and a lover of science, who brought many 

 scientific men together at his pleasant villa. Both 

 Stensen and Swammerdam were hospitably received by 

 Thevenot, who continued a true friend to Swammerdam 

 throughout all his subsequent troubles. Amidst the 

 lively throng which gathered at Th^venot's house 

 Swammerdam always remained silent ; his powers were 

 only revealed when he could be induced to exhibit his 

 marvellous skill in unravelling the intricacies of insect 



^Suppressed, together with the colleges of Die, Vitrd, Costres, Orthes, 

 Sedan, Nismes, and La Rochelle by Louis XIV in 1685. Montaul>an alone 

 was allowed to survive. 



