ZOOLOGY AND BOTANY, MIOEOSOOPY, ETC. 



699 



fine focusing screw is at tlie top of the limb, but acts not on the tube 

 but on the stage, causing tbis to slide up or down. The mirror-bar 

 is of somewhat uncommon form, having a hinge-joint close beneath 



Fig. 123. 



Fig. 124. 



the stage on which it can be swung considerably forward for oblique 

 illumination ; the mirror also slides in a slot to focus the light on the 

 object. 



Fig. 125. 



A mechanical stage can be applied on the ordinary stage ; the 

 mechanism is shown in fig. 123 (upper side) and fig. 124 (lower 

 side). This construction has been largely adopted (with more or less 



