ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



95 



the light, and vertical adjustment enables the operator to keep the lamp 

 at a constant distance from the object under examination. 



A shutter (fig. i), which slips inside the lamp circle, may be placed 

 ander the lamp to cut off the light from one half of the circle so as to 

 produce shadows where these prove desirable. Where depth without 

 shadows is desired the shutter is unjiecessarj. 



The absorption disk is a dull black disk (fig. 5) for covering highly 

 polished surfaces, so that only the small portion under examination is 

 exposed to the light. 



For photomicrographic work the illuminator is attached as already 

 described and the camera employed without lenses except those contained 

 in the oljjective and ocular. 



Excellent results have been obtained with low-power objectives from 



Fig. 4. 



Pig. 5. 



GO mm. to IG mm. By using the stage adapter for ;-)2 nun. and less 

 powerful objectives it is possible to place the lamp about -|-in. from the 

 object and obtain beautiful effects. This is of advantage also with the 

 double ol)jective binocular microscope. 



The illuminator has proven satisfactory for oil-immersion work with 

 a 1-8 mm. objective and lox ocular (1425 diameters). The markings 

 on diatoms and structure of fine-grained alloys .show clearly. 



