CHAPTER 10 



Making, Wholemounts 



The last few chapters have surveyed a few of the reagents and processes 

 used in the preparation of microscope slides. It is now time to turn in 

 more detail to the preparation of the slides themselves. Those described 

 in this book are prepared in any one of four ways. First there are whole- 

 mounts, which, as the name indicates, are mounts either of whole organ- 

 isms or of parts of organisms that are sufficiently small or transparent 

 to be studied without specialized treatment. Second, described in the next 

 chapter, are smears, in which a thin layer of some fluid intended for 

 study is spread upon a slide and there stained and mounted. Third are 

 squashes, a self-explanatory term. Last are sections, or thin slices cut from 

 an object either too thick or too complex to be studied as a wholemount; 

 the preparation of sections is described in Chapter 12. Wholemounts are 

 the easiest of all slides to prepare and should be the first to be made 

 by the beginner. 



TEMPORARY WHOLEMOUNTS 



Temporary wholemounts are prepared by every student for the pur- 

 pose of examining material under a microscope. No object should ever 

 be examined on a slide until the coverslip has been placed over it. The 

 purpose of the coverslip is not only to prevent water from condensing on 

 the lenses but, also, to provide a flat surface for observation. Temporary 

 wholemounts are usually prepared in water by the simple process of tak- 

 ing a drop of the fluid containing the material to be examined, such as 

 living Paramecium, and lowering the coverslip on the surface. This is 

 perfectly satisfactory, providing it is not necessary to observe the objects 

 for long periods. After a time, however, the water evaporates from the 

 edges of the coverslip, which crushes the material. This may be avoided 

 readily by slowing the evaporation with petroleum jelly, a little ring or 

 square of which is built up in the center of the slide before the drop is 

 placed in position. The coverslip is pressed down very gently, until it is 

 seen to be sticking to the petroleum jelly. 



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