PRELIMINARY MICROSCOPIC WORK 1 



A. Dissecting Microscope 



1. Examine, with the dissecting microscope, a slide on which a printed 

 word has been permanently mounted. What apparent movement results 

 when the slide is moved to the right? To the left? When it is moved 

 toward, and away from you ? When it is rotated ? 



B. Compound Microscope 



2. After having carefully studied the previous section on " The Use and 

 Care of the Compound Microscope," examine, with the lowest power of 

 the compound microscope, a letter from the preparation you have been 

 studying. What apparent movement results when the slide is moved to 

 the right? To the left? When it is moved toward and away from you? 

 When it is rotated? See that the position of the slide is such that the 

 letter is in normal reading position, and then draw the letter in its apparent 

 position and magnification as seen through the microscope. 



3. Replace the low-power eyepiece No. 2 with the high-power eyepiece 

 No. 2 . Draw the letter. 



4. Replace the high-power eyepiece No. 2 with the low-power eyepiece 

 No. 2 and, by revolving the nosepiece, replace the low-power objective 

 No. 2 with the high-power objective No. 2 . Carefully refocus with the 

 fine adjustment. Draw the letter. 



5. Without disturbing the objectives replace the low-power eyepiece 

 with the high-power eyepiece. Draw the letter. 



6. In some microscopes the magnification can be still further increased 

 by extending the draw tube. Extend it to its full length and, after refocus- 

 ing, note the effect on the magnification. 



7. Examine, with the low power, a preparation of scales from the wing of 

 a Moth or Butterfly. Make several outline drawings showing different 

 types of scales. 



8. Examine, with the high power, and study the markings on the surface 

 of the scales and make a drawing of a portion of a scale to show their 

 character. 



9. Mount and make a microscopic examination of various tiny 

 objects which are readily available. These may include particles of dust ; 

 fibers of hair, cotton, silk, etc. ; air bubbles in water ; and globules of oil 

 in a mixture, or emulsion, of oil and water. 



1 B. pp. 241-244. 2 Instructor will supply information. 



245 



