THE COMPOUND MICROSCOPE 



other liquid should be covered with a cover-slip, 

 an exceedingly thin circle or square of glass. The 

 cover-slip is as much a protection for the objective 

 as for the object and its cleanliness also, is all 

 important. 



We have not mentioned any refinements such as 

 the mechanical stage, by means of which slides on 

 the stage may be rotated, moved to the front and 

 to the back of the stage or from side to side. We 

 have omitted these because they are not essential 

 even for the very best work; they lend additional 

 comfort to the use of the microscope but, again, 

 they are not essential. The microscopist who re- 

 quires such luxuries may learn about them in the 

 larger text-books on the microscope. 



65 



