HIGH-POWER AND ROUTISE MICROSCOPY 19:} 



3. If the condenser light cone refuses to fill the back 

 of the high-power oil objective, adjustments being appar- 

 ently correct, the water immersing the condenser has 

 probably dried up or slid off. 



4. If the water used for immersing the condenser is 

 continually running off, or retains bubbles, clean upper 

 lens of condenser and lower surface of slide with xylol. 



5. If there is something wrong with the definition in an 

 oil-immersion (or water-immersion) objective, look down 

 the tube at the back of the objective (or look at the eyepoint 

 through a magnifier), and see if there is a bubble visible 

 in the immersion fluid. 



6. If the definition is injured in a way which experience 

 shows results from the light being one sided, look at the 

 back of the objective, and it may be found that the reflect- 

 ing prism (or mirror) is out of center with the lamp and 

 condenser. 



7. If the image found after focusing down with the oil- 

 immersion objective (especially the 60) is unexpectedly 

 dull, it may be that there is not enough oil to make contact. 



8. If on pressing out a cell in acetocarmine or immersion 

 oil by pressure on the cover with a knife blade, the slide 

 breaks, it is usually because the condenser has not been 

 racked up into contact so as to support the slide. 



9. If the oil-immersion objective is focused too far down 

 on the cover-glass, so as to break the object, this may be 

 because the small diaphragm has not been put on the 

 source, and its image focused in the plane of the object. 



10. If the high dry and oil-immersion objectives catch on 

 screw heads of the stage, and so are damaged, it may be 

 because they are not raised before revolving. 



11. If the object shows poor definition, it may be because 

 the objective has slid slightly past the catch on the nose- 

 piece; or the objective may be screwed loosely in its socket. 



12. If the front lens of the objective of 1.4 aperture is 

 pushed in, it may come from not putting the 3-millimeter 

 diaphragm on the radiant, from not raising the objective 

 slightly after oil contact is seen to be made, from too little 



