20 



THE STRUCTURE OF 



various objects which the observer has in view. 

 As this is a book for beginners, we shall only- 

 mention a few of these. 



Microscopes are generally supplied with small 

 slips of glass, three inches long and one inch wide. 

 These are intended to place the objects on which 

 are to be examined. They are either used tempo- 

 rarily or permanently with this object in view, 



Fig. 8. Forceps. 



and are called slides. "When used temporarily, an 

 object, such as a small insect, or part of an insect, 



Fig. 9. Bull's-eye Condenser. 



is placed upon the middle of it ; and it may be 

 either placed immediately upon the stage at the 



