APPENDIX. 107 



example of this class is seen at fig. 115. An interesting species 

 for observation will be found in the Anguillula glutinis, found 

 in sour paste. 



Ferns and Mosses. The investigations into the structure 

 of the minute reproductive organs of these plants form an 

 interesting branch of microscopy. Mosses (more especially at 

 the time of the year when nature partially hides her glory) 

 may be taken up as a special object of study ; for their struc- 

 tural peculiarities are developed chiefly in winter. Many of 

 the smaller species may be mounted entire, after soaking for 

 a short time in water and draining off the same : they show 

 well when mounted in the silicate of potassa ; but most of the 

 minute characters show best in balsam. The parts of the 

 fronds of various species of Ferns which exhibit the sori show 

 best when mounted dry. 



Lichens, when entire, are mounted dry; but, to show the 

 apothecia &c. well, the sections of the thallus must be mounted 

 in glycerine or balsam. 



Fungi. Sections of spores &c. are generally best when 

 mounted in the preservative fluids, as recommended for the 

 Algse ; but many of the micro-Fungi may be mounted in situ 

 in a dry opaque cell ; and some of the brands &c. show best 

 when mounted in balsam. 



Leaves and Petals. The cuticles of these parts of plants 

 form a large range for investigations. Most cuticles are pre- 

 pared by boiling the leaf in a fluid made by adding about four 

 parts of water to one of nitric acid ; but the proportion must 

 vary according to the nature and strength of the leaf. After 

 the cuticle is separated by boiling in this fluid, it must be 

 floated off from the waste tissue, delicately washed with a fine 

 cameVs-hair pencil, and mounted in a suitable fluid according 

 to its thickness &c., if thick, in glycerine or balsam ; if thin, 

 in any of the fluids recommended for the Algae &c. The cuti- 

 cles of the petals are best when torn from the surface ; but for 

 petals I prefer the colouring- matter to be nearly obliterated 

 by the use of ether; then add weak sulphuric acid, dry, and 

 mount in balsam ; or some show best when mounted dry. 



Most of the other vegetable tissues, such as spiral-vascular, 

 scalariform, &c., are best mounted in glycerine &c. 



