86 PIIEPARATION AND MOUNTING 



microscope. The common screw-moss may be found i 

 great abundance, and shows this denudation of the spores- 

 very perfectly. Many of these may be easily dried without 

 much injury, but they should also be examined in their 

 natural state. 



The student should not omit from his cabinet a leaf of- 

 the nettle and the allied foreign species, the mystery ot 

 which the microscope will make plain. The hairs or stings 

 may also be removed, and viewed with a higher power than 

 when on the leaf, being so transparent as to require no bal- 

 sam or other preservative. 



There are few more interesting objects than the raphides 

 or plant-crystals. These are far from being rare, but in 

 some plants they are very minute, and consequently require 

 care in the mounting, as well as a high magnifying power 

 to render them visible; in others they are so large that 

 about twenty-five of them placed point to point would reach, 

 one inch. Some of these crystals are long and compara- 

 tively very thin, which suggested the name (raphis, a 

 needle) ; others are star-like, with long and slender rays - t 

 while others again are of a somewhat similar form, each ray 

 being solid and short. If the stem of rhubarb, or almost 

 any of the hyacinth tribe, be bruised, so that the juice may 

 flow upon the slide, in all probability some of these crys- 

 tals will be found in the fluid. To obtain them clean,, 

 they must be freed from all vegetable matter by maceration^ 

 After this they must be thoroughly washed and mounted 

 dry. They are also good polarizing objects, giving bril- 

 liant colours; but when used for this purpose they must 

 be mounted as described in Chapter IV. A few plants 

 which contain them may be mentioned here. The Cac- 

 tacese are very prolific ; the orchids, geraniums, tulips, and 

 the outer coating of the onion, furnish the more unusual 

 forms. 



The Fungi are generally looked upon as a very difficult 

 class of objects to deal with, but amongst them some oi 

 the most available may be found. The forms of many are 



