THE MINUTE ANATOMISTS 33 



lacked that concentration which made the work of 

 Swammerdam so productive and so lasting. 



Leeuwenhoek worked with simple lenses, ground and 

 mounted by his own hands. It was easy to make 

 lenses of high magnifying power, but hard to correct 



ANTONY VAN LEEUWENHOEK. 



From the portrait by Verkolje, prefixed to the Epistolce ad Soc. Reg. Angl. t 

 Leyden, 1719. 



their optical defects, to bring a sufficiently strong light 

 to bear upon the object, and to focus the lens. When 

 he wished to send out his preparations for examination 

 by others, he found it best to fix the objects in the 



