PART II 



OPTIONAL PRELIMINARY STUDIES 



SECTION I. SUGGESTIONS 



Order of study. ^Vllen you examine any object in the 

 laboratory, the proper method of procedure is as follows : — 



1. Discover all you can about it with the unaided eye. 



2. When small, use a hand lens or magnifying glass. 

 The sign {m) in this book refers to such an instrument. 



3. If the object is very small, the compound microscopic 

 may be required. The signs (Ip) and (Jip) refer to low and 

 high powers of this instrument. The parts and use of a 

 compound microscope ought to be familiarized by reference 

 to charts or books furnished by instrument makers. 



4. After a thorough study of the object, drawings are to 

 be made showing all that you have discovered. 



5. Finally, complete notes, descriptions, or other written 

 work are to be made, showing all that you have discovered. 

 These are to be preserved in connection with the drawings. 



Tools for work. The instruments named in Order of Study 

 together with certain others, as the projection lantern and 

 the opaque projector, will enable you to see the object. To 

 assist in handling the object other tools are sometimes used, 

 as needles, scissors, forceps, scalpels, and, at times, apparatus 

 of different kinds. 



The projecting lantern, which throws upon the screen images 

 from the lantern or microscope slides, is a very important laboratory 

 help, supplementing the compound microscope, and is often used in 

 well-equipped laboratories. The advantage derived is often very great, 

 saving time and labor, and insuring that all pupils see just the impor- 

 tant features of structure most essential to a proper understanding of 

 the subject. 



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