OUTLINES OF BOTANY. xlvii 



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 hu- 

 midity of the specimens ; 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 ; 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 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 lat- 

 tice, 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 di- 

 rection. 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 de- 

 licate 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 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 



