372 



METHODS IN PLANT HISTOLOGY 



scopic objects; one by means of the ocular micrometer; and the other, 

 by means of camera lucida sketches. 



Measuring with the ocular micrometer. — A stage micrometer and 

 an ocular micrometer are necessary. A stage micrometer should be 

 ruled in tenths and one-hundredths of a millimeter. It does not matter 



SECULARS 



iNctmES 



SiNOCULftR BODY* 



NOSE PIECE 



OBJECTIVES 



R/\CK K PIKION 

 COARSE /ADJUSTMENT 

 BUTTONS 



INTERMEriflTE 

 SLIDE 



HORSE SHO 

 BASE 



Slide crrriers of 



MECHflNICHl. 

 STAGE 



SCREW FOU 

 CENTERINq 

 STAGE ^^^-^ 



o3li(?ue light" 



P|/\PHRA<SM -~ 

 CONDENSER MOUNTINS 

 1R\S DIAPHRAGM 



SCREW FOR CENTERING^ 

 CONDENSER 



MlRT^OR 



KEvoLvms 

 / STAGE 



ARM 



MeCHflNICAL 



STAGE 



ADJUSTMEMT 



BUTTONS 



VERMIEf^ 



■PINE ADJUSTMENT 



"" Buttons 

 INCLINflTJOM JOINT 

 - — PILLAR 



— Pinion Button for 

 RACKS Pinion 

 substage 



mirrorForI 



Fig. 137. — A modern microscope 



what the spacing in the ocular micrometer may be, except that the 

 lines must be at equal distances from one another. As a matter of fact, 

 the ocular micrometer is generally ruled in tenths of a millimeter, but 

 this ruling is more or less magnified by the lens of the ocular. 



Place the stage micrometer upon the stage and the ocular microme- 

 ter in the tube, and arrange the two sets of rulings so that the first 

 line in the ocular micrometer will coincide with the first line of the 



