THE MICEOSCOPE. 21 



proper distance from the object-glass, or a drop of 

 water may be placed on the slide, and a piece of 

 thinner glass placed over the object. This is the 

 most convenient arrangement, as yon may then 

 tilt your Microscope without the slide or" object 

 falling off. 



Objects, when placed under the Microscope, are 

 of two kinds either transparent or opaque. When 

 they are opaque, they may either be placed upon 

 the slips of glass, or put between a small pair of 

 forceps (fig. 8), which are fixed to the stage of the 

 Microscope, and the light of a window or lamp 

 allowed to fall upon them. This is not, however, 

 sufficient, generally, to examine things with great 

 accuracy; and an instrument called a condenser 

 (fig. 9) is provided for this purpose. It consists 

 merely of a large lens, which is sometimes fixed to 

 the stage, or has a separate stand. Its object is to 

 allow a concentrated ray of light to be thrown on 

 the opaque object whilst under the object-glass of 

 the Microscope. This is called viewing objects by 

 reflected light. 



Transparent objects, on the other hand, are 

 viewed by transmitted light, reflected from the plane 

 or concave surface of the mirror beneath the stage. 

 The object of this mirror, which is called the reflector, 

 is to catch the rays of light and concentrate them 

 on the object under the Microscope. The rays of 

 light thus pass through the object, and its parts are 

 seen much more clearlv. 



Another convenient piece of apparatus is an 

 animalcule cage. This consists of a little brass box, 

 inverted, to the bottom of which is attached a piece 

 of glass. Over this, again, is placed a lid or cover, 

 with a glass top. The cover can be made to press 

 on the glass beneath, and an object being placed 

 between the two glasses, can be submitted to any 



