INTIIOBUCTION. XXXUl 



it, and the sooner the plants will dry. The paper ought to be coarse, stout, and unsized. 

 Common blotting-paper ia much too tender. 



236. Care must be taken that the paper used is well dried. If it be likewise hot, all 

 the better ; but it must then be very dry ; and wet plants put into hot paper will 

 require changing very soon, to prevent tlieir turning black, for ho'tdamp without ven- 

 tilation produces fermentation, and spoils the specimens. 



237. For pressing plants, various more or less complicated and costly presses are 

 rnade. ^one 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 

 ti-avelling. Each of these boards should be double, that is, made of two layei-s 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 2i lines) will be found hght and durable. 



238. It is useful also to have extra boards or pasteboards the size of the paper, to 

 separate thick plauts from thin ones, wet ones from those nearly dry, etc. Open 

 Mooden 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 plauts are shifted into dry paper the better. Except- 

 ing for very stiff or woody plants, the first pressure shoukl be hght, and the first sliift- 

 ing, if posi^ible, after a few hours. Then, or at the second -shifting, when the specimens 

 will have lost then' elasticity, will be the time for putthig 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, aiul the plants left from one to several days without shifting. 

 Ihe exact amount of pressure to be given will depend on the consistence of the speci- 

 niens and the amount of paper. It must only be borne in mind that too much pres- 

 sure crushes the delicate parts, too little allows them to shrivel, in both ca»es inter- 

 tcrmg with their future examination. 



^ 210. The most convenient specimens -will be made, if the drying-paper is the snme 



• size as that of the herbarium in which they are to be kept. That of writing-demy, 



rather more than ItJ inches by lOj. inches, is a common and very convenient size. A 



small size reduces the sijccimens too much, a larere size is both costl\- and hicouvenicnt 

 lor use. 



.^^^' 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. 

 Ihe specimens may be placed very closely on tlie sheets, but not in more tlmn one 

 layer on eaeh sheet, and care must be taken to protect the bundles by sufficient cover- 

 ing from the effects of external moisture or the attacks of insects. 



242. In laying the specimens into the Jierbai^ium, no more than one species should 

 ever be fastened on one sheet of paper, altiiough several specimens of the same species 

 ^ay be laid side by side. And throiighout the process of diying, packing, and laymg 

 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 moistening 

 tlieiu 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 dL^sect them 



244. For dissectlnir and examining flowers in the field, all that is necessary is a pen- 

 Kuite and a pocket-lens of two or three glasses from 1 to 2 inches focus. At home it 

 ^ ^°^ convenient to liave a mounted lens or simple microscope, with a stage holdmcr 

 a glass i)lLite, upon which the flowers may be laid; and a pair of dissectors, one ot 

 J^lHch should be narrow and pointed, or a mere point, like a thick needle, m a humUe,; 

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

 nie ovary. A compound microscope is rarely necessary, except in cryptogamic botany 

 f^<^ vegetable anatomy. For the simple microscope, lenses of i, i, 1, and U hk^^i^s 

 wus are suffieient. 



245. To assist tlie student in determining or ascertaiiiing tlie name of a plant be- 

 longing to a Flora, analytical tables should be prefixed to the Orders, Genera, flnd 



