ELEMENTARY BOTANY. 
XXX111 
all the better ; but it must then be very dry ; and wet plants put into hot paper 
will require changing very soon, to prevent their turning black, for hot damp with- 
out ventilation produces fermentation, and spoils the specimens. 
237. For pressing plants, various more or less complicated and costly presses are 
made. None is better than a pair of boards the size of the paper, and a stone or 
other heavy weight upon them if at home, or a pair of strong leather straps round 
them if travelling. Each of these boards should be double, that is, made of two 
layers of thin boards, the opposite way of the grain, and joined together by a row of 
clenched brads round the edge, without glue. Such boards, in deal, rather less than 
half an inch thick (each layer about 2\ lines), will be found light and durable. 
238. It is useful also to have extra boards or pasteboards the size of the paper, to 
separate thick plants from thin ones, wet ones from those nearly dry, etc. Open 
wooden frames with cross-bars, or frames of strong wire- work 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. Ex- 
cepting 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 inconve- 
nient 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 external 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 necessary to 
soften them. If the parts are very delicate, this is best done by gradually moist- 
ening 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 necessary is a 
penknife 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 dis- 
sectors, one of which should be narrow 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 inches focus are sufficient. 
245. To assist the student in determining or ascertaining the name of a plant be- 
longing to a Flora, analytical tables should be prefixed to the Orders, Genera, and 
Species. These tables should be 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 stu- 
d 
