LEEUWENHOEK’S MICROSCOPES 320 
Brains of a fly. 
Optic nerves of a fly. 
Tips of the feet of a fly. 
Sting and sheath of a flea. 
Feet » 9 99 
HKyes of a dragon-fly. 
» 99 beetle. 
Sting of a louse. 
MGM: 59 1 Sp of 
Ovipositor ,, 5, aa 
Red coral. 
Section of oyster-shell. 
Embryo oysters in a little [glass] tube. 
Vegetable Objects 
Transverse and longitudinal sections of elm-wood. 
” ” ” ” » fir-wood. 
»” ” ” »” »” ebony. 
»” »” ” » »” lime-wood. 
»” ” om) »” »” oak-wood. 
” » ” ” » Clnnamon. 
» » ” » »» cork. 
” » ” 5) » rush. 
Section of fossil wood. 
Germ out of the seed of rye. 
Vascular bundles out of a nutmeg. 
Mineral Objects 
Bits of white marble, rock-crystal, diamond, gold-leaf, 
gold-dust, silver-ore, saltpetre, crystals, etc. 
Harting was fortunately able to examine one of Leeuwen- 
hoek’s few surviving lenses carefully: and as his tests are the 
only recent ones made by an expert—so far as I am aware—I 
must here note what he found. He reports* that the biconvex 
lens which he studied was “really very good indeed”’, and 
proved that its maker had attained “a very high degree of 
proficiency in grinding extremely small glasses.” Its magni- 
fying power was no less than 270 diameters [indicating a focal 
1 Het Mikroskoop (1850), Vol. III, pp. 43, 44. 
