ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
517 
The circular stage, graduated in degrees, is about 120 mm. in 
diameter, and is rotated by hand. For the orientation of the object, it is 
provided with a millimetre scale (100 mm.) along two diameters at right 
angles, and the diameters iuclined to these at 45° are also provided with 
a division. The upper part of the stand is of the same form as in other 
Fig. 54. 
Zeiss models. The lower part of the body-tube has a centering arrange- 
ment c c provided with the Society screw. Near the end of the tube is a 
side opening in which slides a frame by means of the knob K. In the 
frame are two apertures side by side, one of which serves for the recep- 
tion of a quartz plate, quarter- wave plate, &c., while the other usually 
remains empty, but may be used to receive a second plate. The draw- 
