XXX INTRODUCTION TO BOTANY. 



and of specimens, till yon have cither placed in paper all the specimens 

 collected, or made a siillliciently thick pile. Cover the pile with one of the 

 flat boards, and place upon it a heavy weight, — large stones or bags of 

 sand answer perfectly. If travelling, leather straps and buckles, drawn 

 tightly across the bundle, are used instead of weights. 



194. After the specimens have lain a day under pressirre, the paper 

 about them must be removed, and dry papers substituted ; and this process 

 should be repeated at intervals of a day or two till the plants are perfectly 

 diy. If many sheets of paper be placed between each layer of specimens, 

 or if open frames be used instead of boards, the changes need not be so 

 fi'equent. In changing it is not necessary to lift every specimen from the 

 sheet on which it lies ; but if a dry sheet be placed over the specimens, 

 the latter, wath the moist sheet, may be tilted over to the dry, and the 

 moist sheet then removed, and this process repeated thi'ough the bundle. 

 Much time and trouble may thus be saved. 



195. On the fiist day of shifting a sharp look-out should be kept for 

 caterpiUars^ which are apt to secrete themselves in flowers, and, if not at 

 once removed, will quickly destroy the specimens imder pressure. 



196. In fine weather the bundles of specimens, weighted or strapped, 

 may be exposed to the strongest heat of the sun ; but as this causes a 

 rapid extraction of moisture, in order to ensure its passing away, the 

 plants must, on bringing in, and while still wann, be shifted into fresh 

 papers : otherwise mouldiness and decay, and not exsiccation, T\dll ensue. 

 Artificial heat, not greater than 140°, may be substituted in wet weather. 



197. In di'}Tm.g plants within the tropics, and in all damp and hot 

 climates, frequent shifting of papers is necessary ; if neglected, the 

 specimens will either faU to pieces, or become mouldy and rotten. 



198. Fleshy fruits should be preserved in spirits ; or carefully stretched, 

 and the seeds or hard parts dried. 



199. Succulent plants. Heaths, and plants with compound leaves (such as 

 Mimose<R), should be dipped (all but the flowers) for a few seconds into 

 boiling water, before being placed in the drjang-papers. This wdll hill 

 them, promote the di-j-ing of succulents, and prevent the Heaths, etc., 

 from shedding their leaves. 



200. Plants wdth delicate corollas {Iridece^ Oxalidece, etc.), should be 

 placed between single leaves of very thin and soft, imglazed paper 

 (filtering or tissue-paper). In shifting to day papers the tissue-paper 

 is not to be removed, but lifted v^ath its contents to the dry layer. 

 This will prevent the flowers from curling up or perishing. 



201. When the specimens are quite di-y and stitf, a sijujle sheet of paper 

 is sufficient between each layer ; they may be placed still more closely on 

 the sheets, but not piled one on another ; and, finally, in sending specimens 

 fi-om a distance, great care must be taken to protect the bimdles, by 

 sufficient covering, from the effects of external moisture, or from the 

 attacks of insects. 



202. Ha\'ing dried his plants, the student begins to form his Herba- 

 rium, or HortiDi Siccus. The fii'st step is to assort the specimens, first 

 into their classes ; then into subclasses, Orders, (jenera, and spjecies. When 

 this is done, he selects such specimens of such species as he wishes to 

 retain for future reference, coi^ig-ning the remainder to separate bimdles 

 labelled " duplicates,'' and keeping them for exchange with other 

 botanists. 



203. The specimens selected, having first been examined and named, 

 are either fastened with thin glue to pieces of stiff white or cream-coloured 

 cai-tridge-paper of a uniform size, or placed loosely, or secured by cross- 

 bands or pins, in double .'^heets of soft paper. In either case the species 

 belonging to each genus are placed -sNathin a common wrapper of strong 



