XI. WHEN TO USE SPECIAL MICROSCOPES 



355 



2. The Stereoscopic, Biobjective Microscope 



Opaque specimens may be examined to advantage with the stereo- 

 scopic, biobjective binocular microscope, although it is not limited to 

 such specimens (c/. Sect. Jl). The microscope (Fig. 3) is really com- 

 posed of two microscopes, one for each eye. Erecting prisms are 



EYEPIECE 



EYE LENS 



Fig. 3. The biobjective, stereoscopic microscope. 



included so that the image is not inverted, as with the monobjective 

 compound microscope, and dissecting operations and other manipula- 

 tions made on it are normal. Since each eye sees a separate view 

 from a different angle the microscope shows real stereoscopic depth 

 and the greatest applications concern observations in which the third 

 dimension is essential. When the converging angles between the 



