242 THE MICROSCOPE. 



ing the glasses should be perpendicular, and the stage 

 therefore horizontal. Most objects in human anatomy are 

 examined in Avater or in other liquids, or they are them- 

 selves liquids; hence an oblique stage is often incon- 

 venient. 



10. Additional Apparatus. As almost all objects 

 in human anatomy are examined by transmitted light 

 thrown up from the mirror (G, Fig. 60) 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 pro- 

 cured 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 alcohol and water. Simple water will not re- 

 move 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 or- 

 dinarily 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. 



10. Slides ? Covers, square and circular? How kept? 



11. Cleaning the glasses ? Knives, scissors, etc. ? various liquids? 



