54 PREPARATION AND MOUNTING 



and viewed with a higher power than when on the leaf, being so 

 transparent as to require no balsam, 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 mount- 

 ing, 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 comparatively very thin, which suggested the name 

 (rapkis, a needle) ; others are star-like, with long and slender 

 rays ; 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 crystals 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 brilliant colours; but when used for 

 this purpose they must be mounted as described in Chapter III. 

 A few plants which contain them may be mentioned here. The 

 Cactacese 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 of the most availa- 

 ble may be found. The forms of many are very beautiful, but are 

 so minute as to require a high magnifying power to show them. 

 The mould which forms on many substances is a fungus, and in 

 some cases may be dried and preserved in its natural state. A 

 friend of mine brought me a rose-bush completely covered with a 

 white blight. This was found to be a fungus, which required a 

 high magnifying power to show it. Being a very interesting ob- 

 ject, it was desirable to preserve it, and this was perfectly effected 

 without injury to the form by simply drying the leaf in a room 

 usually occupied. Amongst the fungi are many objects well 

 worth looking for, one of which is the Diachcea elegans. This, 

 the only species, says the " Micrographic Dictionary," is found in 

 England upon the living leaves of the lily-of-the-valley, &c. These 

 little plants grow in masses, reminding one of mould, to a height 



