82 



BIOLOGY AND ITS MAKERS 



Nierstrasz from ihc s])ecimen in possession of the University 

 of Utrecht. The instrument consists of a double cop])er plate 

 in which the circular lens is inserted, and an object-holder — 

 represented in the right-hand lower figure as thrown to one 



Fig. iq. — Leeuwenhoek's Microscope. 

 Natural size. From Photographs by Professor Nierstrasz, of Utrecht. 



side. By a vertical screw the object could be elevated or 

 depressed, and by a transverse screw it could be brought 

 nearer or removed farther from the lens, and thus be brought 

 iiUo focus. 



Fig. 2oa shows the way in which the microscope was 



