28G THE U.SE OF THE MICROSCOPE 



Micrometer, object or stage. An accurately divided scale, usually 

 in hundredths of a millimeter, mounted as an object. Best when 

 engraved. The slide it is on should be of standard thickness. Indis- 

 pensable for all measurements. 



Micron, The unit of microscopical measurement, 0.001 millimeter. 



Microscope. An instrument for magnifying near objects, mounted 

 on a stand. Usually a compound microscope with objective and 

 eyepiece. 



Microscope, standard. An instrument mainly for medium and 

 high-power work, with a condenser, and usually no objective below 

 8 or 10 times. 



Microscopy. The science and art of the microscope. 



Microscopist. A practiced user of the microscope. 



Microtome. Machine for cutting thin slices (sections) of plant or 

 animal tissues, usually after permeation with paraffin wax, or with 

 celloidin. Sections in paraffin may be cut of one micron in thickness. 

 If there are no kinks, and the layer of balsam is as thin as possible, 

 these sections may almost or quite touch the cover-glass when mounted, 

 which is the desirable condition. 



Monochromatic light. (1) In the strict sense, light of one wave 

 length; as the green of the mercury- vapor lamp, when the yellow, blue, 

 and violet have been removed by a suitable screen. (2) Approximately, 

 light of one color, such as yellow-green, when the red, orange, blue, and 

 violet have been screened out. 



Monobjective binocular. Binocular with division of the beams 

 after passage through the objective (Abbe, Jentzsch). 



Monocular microscope. Instrument with only one tube, and only 

 one eyepiece; so that one eye is unoccupied. 



Mounting an object. Spreading it flat between slide and cover-glass 

 in a suitable medium, after teasing it out, or after sectioning; and usually 

 after staining, also. 



Myopy. State of the eyes in which the distance point is fairly close, 

 and the near point is closer than 8 inches or so. Remedied by concave 

 spectacles. 



Nicol prism. A bisected and recemented rhombohedral prism of 

 natural calcium carbonate (Iceland spar), which transmits only half the 

 entering light (which should be of approximately plane waves). This 

 half is polarized in one plane. 



Non-stereoscopic binocular. Microscope in which the beam is 

 halved by partial reflection and partial transmission at a half-silvered 

 surface, so that the two images are identical. It may be made stereo- 

 scopic by halving the exit pupils. (Abbe, Jentzsch.) 



Nosepiece, revolving. Arrangement for changing objectives. A 

 good fine motion arrangement will bear the weight of a nosepiece with 

 four objectives. The mechanical tube length must include the depth 



