THE MICROSCOPE 337 



ror beneath the stage through the object to the eye, they must 

 be placed upon strips of clear glass about three inches long, 

 and one inch wide, commonly called " slides." These should 

 be procured with the microscope. Again, most objects seen 

 with high powers require to be covered with a thin plate of 

 glass, very properly called a " cover," that the moisture of the 

 specimen may not tarnish the object-glass. Square or circular 

 covers of very thin glass are therefore provided ; and a good 

 supply of these should be always on hand. These glasses 

 should be kept in a covered dish filled with a mixture of alco- 

 hol and water. Simple water will not remove the fatty matter 

 which exists in all animal tissues, and, therefore, the glasses 

 cannot be thoroughly cleaned with it alone. 



11. When glasses are required for use, they should be 

 removed from the liquid and wiped clean and dry with a soft 

 linen handkerchief. Delicate knives, scissors, needles mounted 

 in handles, forceps, pipettes or little tubes for taking up water, 

 should be obtained; these are essential to all microscopical 

 study. The table should be supplied with glass-stoppered 

 bottles containing the various liquids ordinarily used in the 

 study of physiology. Thus, tincture of iodine is indispensable 

 in studying vegetable structure, acetic acid in the study of 

 animal tissues ; and other articles will have to be added from 

 time to time, as your progress in study demands them. 



12. Preliminary Studies. In order to prepare the way for 

 the study of any department of science with the aid of the 

 microscope for the microscope is but an eye, and can be 

 turned in almost any direction for purposes of investigation 

 it is necessary to become acquainted with the many objects 

 which are liable to complicate the examination of particular 

 structures. Both air and water are full of floating bodies, 

 and the most common of these should first occupy the atten- 

 tion. In the city, particles of starch are always floating in the 

 air. Take a very minute portion of wheat flour, place it in the 

 middle of a clean glass " slide," drop upon it a drop of pure 



11. Cleaning the glasses ? Knives, scissors, etc. ? Various liquids f 



12. Bodies, in ah- and water ? The examination of starch ? 



