PRACTICAL BOTANY. 



CHAPTER I. 



APPARATUS AND METHODS. 



1. Simple Lenses. Much useful work can be done 

 with simple lenses, and it is often advisable to examine 

 specimens with a lens before proceeding to use the com- 

 pound microscope. 



(a) The best kind of simple lens is the aplanatic or 

 " platyscopic," which gives a flat field of view, without 

 distortion of the margins, but an ordinary double or triple 

 folding or pocket lens will suffice. 



(6) For various pur- 

 poses it is useful to have 

 a watchmaker's lens, with 

 a piece of string or elas- 

 tic to fasten it round the 

 back of one's head, and 

 thus leave both hands 

 free in examining the 

 specimen. 



2. Lens Stand. It 



is easy to make a simple 

 stand to carry the lens 

 and allow of both hands Fig> L _ A Lens ?older) with movable arms 



being Used 111 dlSSectlOll. and rack-and-pimon focussing adjustment. 



The lens can, for in- 

 stance, be fixed to a cork which slides up and down a 

 vertical rod inserted into a firm and fairly heavy base ; 



P.B. 1 



