CHOICE AND USE OF APPARATUS 



by the beginner, as easily as larger stems. For such 

 objects little sticks of pith are sold as holders. 

 Having cut of our piece of leaf from which we wish 

 to derive a section, we make a slit, with our dissect- 

 ing knife, down the middle of one end of a piece of 

 pith. The piece of leaf is then placed in the slit and 

 by holding the pith at the sides our piece of leaf 

 is held firmly. Sections are cut through pith and 

 leaf, and the two are floated in water, when the 

 thin slices of pith will float away from the leaf 

 sections. 



Having cut a satisfactory section, let us proceed 

 to describe the method of making a slide thereof. 

 We will suppose that we do not wish to make a per- 

 manent preparation but one for temporary use. 

 A clean slide must be selected, all through our pages 

 we emphasise the cleanliness of slides, at or near its 

 centre we put a drop of water and, lifting it with i 

 a brush, we place our section in the drop of water. I 

 If our examination is to be with a low magnifi^a- \ 

 tion, we need not use a cover slip, nevertheless it ■ 

 is worth while to cultivate the habit of using one. | 

 The cover slip is not only a protection for our object 

 but for our objective. Water you may argue cannot 

 harm the lenses of the objective. Perhaps not, we 

 will not argue the point but, when the water dries 

 on the objective, it leaves a certain amount of 

 deposit on the glass and this deposit must be rubbed 

 off. The less often the lenses are rubbed the better 

 for them, glass especially very highly polished 

 optical glass, is far more easily scratched than many 



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