1 1^. Living Things Are Basically Alike unit ii 



Examine the mirror. In which directions can it be moved? Note that it 

 has a flat and a concave (hollowed out) surface. Turn the concave surface 

 toward the light. How do the two objectives differ from one another? 

 The shorter one is the low-power objective. Examine the diaphragm care- 

 fully. How does it work? What is it for? Slow ly turn the coarse adjustment, 

 then the fine adjustment. What effect does each have on the barrel? If 

 the microscope is placed before you so that the arm is toward you, how 

 must you turn the wheels in order to move the barrel up? It is important 

 that you remember this. 



z. How to find an object under the low power: {a) Place the micro- 

 scope so that the pillar is toward you wath the base resting firmly on the 

 desk or table, {h) Place the slide on the stage so that the material on the 

 slide is over the hole in the stage. If the object is small, it must be centered 

 over the hole. Hold the slide in place with the uvo clips, {c) Turn the 

 low-power objective (shorter one) until it clicks into place. It ^\'ill then 

 be exactly over the hole in the stage, {d) With your eyes held at the 

 level of the stage, not at the ocular, lower the barrel, using the coarse 

 adjustment, until the tip of the low-power objective is about one fourth 

 inch above the stage, {e) With your eye at the eyepiece turn the mirror 

 so that the concave side is up and secure the best uniform bright light 

 by moving the mirror, (f) Now, with your eye at the eyepiece, slowly 

 raise the barrel by turning the coarse adjustment toivard you. Do this 

 until \ ou can clearly see the material on the slide, (g) You may have to 

 ni()\'e the slide to see some other part of the object. (/:?) If the object is 

 not as clear as it might be, turn the fine adjustment no more than a single 

 revolution, now one way, now the other, to see whether you can focus 

 more accurately. If you still do not get a satisfactory focus, try once 

 more from the beginning, this time focusing more carefully ^\•ith the 

 coarse adjustment before using the fine adjustment. 



3, To focus, using the high power: {a) With the concave surface still 

 on top move the mirror until the best light is obtained, {h) Focus care- 

 fully under the lo-xo power. Make sure that the object you are looking at 

 is in the center of the circle (field of vision), (c) By grasping both ob- 

 jectives, slowly swing the high-power objective into position over the 

 hole in rhc stage without shaking or moving the microscope, (d) With 

 your eye at the eyepiece, move the fine adjustment toward you slowly 

 until the object becomes clear. Use only the fi7ie adjustment. If instead of 

 becoming clearer it becomes less clear, turn the fine adjustment the other 

 wa\-. Bur do not make more than one fourth of a revolution with the 

 fine ;uljustnicnr. 



4. 1 he magnidcd image, ^'ou can learn some important facts about the 

 image you see through the microscope by preparing a slide of a small 

 piece of newsjirinr containing the single letter "c." Place the slide so that 

 the letter is upiighr, as you read it. After you have focused under the low 

 power, write in your notebook a statement that tells how the image is 

 tlifferent from the real letter. Now move the slide to the riohr wh.ile you 



