8o 



PRACTICAL MICROSCOPY. 



through the stage by means of the plane mirror, which on 

 meeting the Lieberkuhn are deflected upon the object, as 

 shown in Fig. 63. Lieberkuhns are not much used at the 

 present time, and can only be applied to objects which are 

 so mounted as to allow of the passage of marginal rays 

 through the slide. 



FIG. 63. 



FIG. 64. 



Side reflectors, which are much used for the illumination 

 of opaque objects, are either mounted in the same manner 

 as stage-forceps, or as shown in Fig. 64, in a collar which 

 spans above the objective, as made by Mr. Swift. 



The side reflector may be used to illuminate opaque 

 objects on the stage very successfully, and with such obli- 

 quity that many delicate markings which are unobserved 



