ii OUTLINES OF BOTANY. 
dry, ete. 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 ora 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 104 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 specimens 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 moistening 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, hke a thick needle, ina 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 
eryptogamic botany and vegetable anatomy. For the simple microscope, 
lenses of +, 4,1, and 1} 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 further indented. The student haying a 
