INTRODUCTION. XXXV 



Orchis, it may be dipped in boiling water all but the flowers. This will kill the plant 

 at once, and enable it to be dried rapidly, losing less of its colour or foliage than 

 would otherwise be the case. Dipping in boiling water is also useful in the case 

 of Heaths and other plants which are apt to shed their leaves during the process of 

 drying. 



234. Plants with very delicate corollas may be placed between single leaves of very 

 thin unglazed tissue-paper. In shifting these plants into dry paper the tissue-paper 

 is not to be removed, but lifted with its contents on to the dry paper. 



235. The number of sheets of paper to be placed between each specimen or sheet of 

 specimens, will depend, on the one hand, on the thickness and humidity of the speci- 

 mens ; on the other hand, on the quantity and quality of the paper one has at command. 

 The more and the better the paper, the less frequently will it be necessary to change 

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

 Common blotting-paper is much too tender. 



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

 the better j 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 without ven- 

 tilation 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 2i 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. Except- 

 ing for very stiff or woody plants, the first pressure should be light, and the first shift- 

 ing, 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 speci- 

 mens, 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 cases inter- 

 fering 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 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 cover- 

 ing 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 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. 



