HI OtJtLJKES OF BOTAifii 



dry, etc. Open wooden frames with cross-bars, or frames of strong wirework 

 lattice, are still better than boards for this purpose, as accelerating the 

 drying by promoting ventilation. 



239. The more frequently the plants are shifted into dry paper the 

 better. Excepting for very stiff or woody plants, the first pressure should 

 be light, and the first shifting, if possible, after a few hours. Then, or at 

 the second shifting, when the specimens will have lost their elasticity, will 

 be the time for putting right any part of a specimen which may have taken 

 a wrong fold or a bad direction. After this the pressure may be gradually 

 increased, and the plants left from one to several days without shifting. 

 The exact amount of pressure to be given will depend on the consistence of 

 the specimens, and the amount of paper. It must only be borne in mind 

 that too much pressure crushes the delicate parts, too little allows them to 

 shrivel, in both cases interfering with their future examination. 



240. The most convenient specimens will be made, if the drying-paper 

 is the same size as that of the herbarium in which they are to be kept. That 

 of writing demy, rather more than 16 inches by 10 inches, is a common 

 and very convenient size. A small size reduces the specimens too much, a 

 large size is both costly and inconvenient for use. 



241. When the specimens are quite dry and stiff, they may be packed up 

 in bundles with a single sheet of paper between each layer, and this paper 

 need not be bibulous. The specimer.3 may be placed very closely on the 

 sheets, but not in more than one layer on each sheet, and care must be 

 taken to protect the bundles by sufficient covering from the effects of ex- 

 ternal moisture or the attacks of insects. 



242. In laying the specimens into the herbarium, no more than one 

 species should ever be fastened on one sheet of paper, although several 

 specimens of the same species may be laid side by side. And throughout 

 the process of drying, packing, and laying in, great care must be taken 

 that the labels be not separated from the specimens they belong to. 



243. To examine or dissect flowers or fruits in dried specimens it is ne- 

 cessary to soften them. If the parts are very delicate, this is best done 

 by gradually moistemng them in cold water ; in most cases, steeping them 

 in boiling water or in steam is much quicker. Very hard fruits and seeds 

 will require boiling to be able to dissect them easily. 



244. For dissecting and examining flowers in the field, all that is neces- 

 sary is a pen-knife and a pocket lens of two or three glasses from 1 to 2 

 inches focus. At home it is more convenient to have a mounted lens or 

 simple microscope, with a stage holding a glass plate, upon which the 

 flowers may be laid ; and a pair of dissectors, one of which should be nar- 

 row and pointed, or a mere point, like a thick needle, in a handle ; the 

 other should have a pointed blade, with a sharp edge, to make clean sections 

 across the ovary. A compound microscope is rarely necessary, except in . 

 cryptogamic botany and vegetable anatomy. For the simple microscope, 

 lenses of ^, |, 1, and l inches focus are sufficient. 



245. To assist the student in determining or ascertaining the name of 

 a plant belonging to a Flora, analytical tables are in this work prefixed to 

 the Orders, Genera, and Species. These tables are so constructed as to 

 contain, under each bracket, or equally indented, two (rarely three or 

 more) alternatives as nearly as possible contradictory or incompatible with 

 each other, each alternative referring to another bracket, or having under 

 it another pair of alternatives farther indented. The student having a 



