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PART II. VEGETABLE HISTOLOGY. 



1. The stand should be well proportioned and 

 solidly constructed, so that it will be firm and not liable 

 to get out of order. 



2. The stage should not be so high above the 

 base that the object cannot readily be manipulated on 

 the stage while the hands are resting 

 upon the table. 



3. It is a convenience, though not 

 a necessity, to have the stand so con- 

 structed that the body may readily be 

 inclined at any angle from the perpen- 

 dicular to the horizontal. 

 For use with some forms of 

 the camera lucida and for 

 photography it is also con- 

 venient if there be a stop at 

 the horizontal. 



4. The stage should 

 be firm, perfectly flat on its 



Fig. 460. — A, Eye-piece. B, The objective. C, The sleeve. D, Arm supporting the 

 sleeve and tube. JS, The " fine adjustment," operated by a screw, for obtaining the exact 

 focus F, The stage, with a pair of spring clips to hold the object or slide. G, A revolving 

 diaphragm, with perforations of various sizes to regulate the amount of light admitted to 

 the objective H, A concave mirror on an axis, which permits illumination of any obliquity 

 beneath the stage. It swings on an arm, by which it may be brought above the stage for 

 the illumination of opaque objects. The instrument, complete without the objective, is 

 called the " stand." 



