32 THE NATURE AND NEEDS OF LIVING MATTER 



References 



Hunter, Essentials of Biology. Chap. III. 

 Hunter, Elements of Biology. Chap. III. 

 Bailey, Plant Breeding. Lecture I. 

 Osterhout, Experiments with Plants. Chap. X. 



EXERCISE (Optional) 



1 A study of the construction and use of the compound 

 microscope. 



THE MICROSCOPE 



1. Note. The microscope, an instrument for making small objects 

 appear larger, comprises two parts : the stand and the lenses. 



2. Note. The stand consists of the following parts: foot or base, 

 pillar, arm, tube, diaphragm, mirror, revolving nose piece, the coarse 

 adjustment, and the fine adjustment. 



a. Describe the location of the perforation in the stage. 

 6. What is its use ? w 



c. What is the use of the revolving wheel, or diaphragm, pivoted to 

 the stage ? 



3. Note. Below the stage is a movable bar carrying the mirrors or 

 reflectors. 



a. In how many different directions can you move the mirrors ? 

 6. What is the advantage of having them movable ? 

 c. What is the use of the mirrors ? 



4. Note. A hollow cylinder containing two lenses fits into the upper 

 end of the tube. It is called the eyepiece or ocular. 



a. Why is the name ' eyepiece ' applied ? 



5. Note. Small brass cases, each containing several lenses, are at- 

 tached to the tube at its lower end : they are the object lenses or 

 objectives. 



a. Why is the name ' objective ' given to these lenses ? 



6. How many objectives are there in your microscope ? 



6. Note. The low power (a slightly magnifying objective) has a 

 short and broad case. The high power objective has a long and nar- 

 row case. 



1 Adapted from Hunter and Valentine, Laboratory Manual. Henry Holt 

 and Company. 



