•xiv 



The mode of arrangement or preservation in the herbarium must 

 be left to individual taste and convenience. The following may 

 be adopted as practically most convenient. Having individual 

 specimens glued down on small or suitably-sized pieces of paper 

 with their names, localities, collector's name, date of collection, 

 and drawings or notes of spores and internal structure appended, 

 fasten these with small pins on quarto single sheets of good cart- 

 ridge paper, from which any particular specimen can be readily 

 removed for examination and replaced as occasion requires. 

 These single sheets are then plaoed in a cover of cartridge paper 

 also of quarto size, and the name of the species written on the left 

 hand corner at the bottom on the outside. These covers, each 

 containing a single species, are enclosed in a quarto cover of thick 

 pasteboard, folded bookwise, marked on the back with the name 

 of the genus, and are kept bookwise on shelves in cabinets, ar- 

 ranged according to the system, and in the larger genera to the 

 seotions, adopted in the following work. Reference to any par- 

 ticular specimen is thus readily practicable, even in the most 

 extensive genus, and oonstant use and practice insensibly and 

 gradually impress on the mind a lasting knowledge of systematic! 

 arrangement. 



The successful study of lichens is not really so difficult as per- 

 sons imagine, if only they will bring to the work, careful painstak- 

 ing observation, delicate manipulation in dissection, and a 

 microscope with a good object-glass of J inch focus. The mode 

 of examination which may be adopted is this. ■ Moisten the 

 apothecium with water, then applying a watchmaker's lens to the 

 eye, make, with a sharp surgeon's knife or scalpel, a very thin ver- 

 tical section through the centre of the apothecium. Place this 

 on the lower glass of a compressor, iu a drop of hydrate of potash 

 which assists in loosening the cohesion of the parts, and swells the 

 spores to their proper shape, bring down the upper glass of the 

 compressor with slight pressure, and place the whole under the 

 microscope, increasing the pressure by the screw of the compressor 

 gradually as vision shows to be necessary. A view is thus ob- 

 tained of the asci, spores, paraphyses, structure, and colour of the 

 hypothecium, &c, and drawings may be made of any of them 

 most readily either with a camera lucida or by throwing the 

 microscope into a horizontal position and placing an oblique steel 

 disk on the end of the eye-piece, on looking through which a picture 

 of the object is thrown on paper and may be traced with a pencil, 

 the extraneous light being excluded by covering the head with a 

 dark-coloured cloth. 



If the spores be mature the application of an aqueous solution of 

 iodine will tinge them or the gelatina hymenea blue, or of a red- 

 wine colour, with or without apreceding blue tinge. This re-action 

 occurs only in some lichens, whilst in others there is no such re-action 

 produced, hence it proves useful as a slight confirmatory character. 

 The formula by which the solution is to be prepared is ; — Iodine 



