CHAPTER III 



APPARATUS FOR HOLDING SPECIMENS FOR 

 EXAMINATION 



All microscopes are provided with some means of attaching 

 slips of glass 01 similai appliances to the stage, and with a means 

 of moving them about in order to bring different portions of the 

 slide into the optic axis of the instrument. 



If the microscope is placed in a vertical position, the stage 



then forms a horizontal table, and the slide or slip may be allowed 



simply to rest on the surface, but it is difficult to move it about 



with a regular and even motion unless it is held in some way. 



stage oups. The simplest holding device is a pair of springs called " stage 



clips" (Fig. 43), which fit into two 



^ holes in the stage and press the slide 



..11 c-=.-==.~^_ down upon its surface. They give 



^ ,.--..- sufficient friction to enable the slide 



Fig. 43. — Stage Clips. to be pushed with the fingers with an 

 even and steady movement. 

 The microscope should, however, not be used with its body in 

 a vertical position unless it is necessary. It causes the observer 

 to bend down in an unnatural manner, which is fatiguing, and is 

 said to interfere with the proper circulation of the blood, and it 

 allows the fluid on the surface of the eye to collect in the line 

 of sight, interfering with perfect vision. If the microscope is 

 inclined to a suitable angle, so that the observer can use it 

 comfortably, most objects can be as readily examined as is the 

 case when the instrument is in a vertical position. Even those 

 objects which are mounted in fluid can be used in this manner, 

 as they are almost invariably enclosed between a glass slip and 

 a cover glass. When used in this position stage clips or some other 

 holding device are essenital. 

 SMing ^ sliding ledge (Fig. 44), which fits on to the edge of a square 



stage and can be slid up and down, is the most convenient simple 

 apparatus for holding a 3 x 1 slip, as a very even motion vertically 

 can be obtained by pushing the ledge up and down, and laterally 

 by pushing the slip to and fro along the edge of the ledge. There 

 are two springs on the ledge which press the slip on to the stage 

 which can, however, be turned aside if not required. A slide 

 can be searched in this way, as the object can be raised by an 



50 



Vertical 

 portion ot 

 microscope. 



