LEEUWENHOEK 221 



every morning. This, he thought, might have killed 

 the animalcules, and his conclusion was confirmed by 

 finding that on the back teeth, which were less exposed 

 to the hot drink, plenty of them were still to be found. 

 In this letter of 1692 he describes and figures angulated 

 rods which moved by rotation on their long axes. In 

 1697 he tells how he pulled out a decayed tooth, and 

 found that the cavity abounded in moving particles. 



Here Leeuwenhoek's study of bacteria comes to an 

 end, except that in 1713, being then over eighty, he 

 speculated a little as to the possibility of bacteria being 

 introduced into the mouth by the rinsing of drinking- 

 vessels in water abounding with infusorial life. After 

 Leeuwenhoek nothing more was done to elucidate the 

 bacteria till 1786, when 0. F. Miiller described and 

 figured several kinds. 



A Microscopical Fraud 



It may relieve the reader's attention to mention 

 a curious fraud which Leeuwenhoek exposes. A long- 

 forgotten writer, Noel Argonne, who used the nom-de- 

 plume of Vigneul-Marville, and whom Voltaire describes 

 (not quite accurately) as the only Carthusian monk who 

 ever made a contribution to literature, relates^ that 

 on arriving in London he and his friends were solicited 

 to buy curiosities. Among these was a microscope, 

 i.e. a lens mounted on tortoiseshell, which he was 

 assured was " si excellent, qu'il ne faisoit pas seulement 

 voir les cirons (mites) les plus imperceptibles ; mais aussi 

 les atomes d'Epicure, la matiere subtile de D^cartes (sic), 

 les vapeurs de la terre, celles que notre corps transpire, 

 et les influences des Astres." On looking at the exhibi- 



1 Mdanges (Phistoire et de literature. 12mo. Paris. 1609-1701. Vol. IT, 

 p. 426. 



