BOOK 1. FORMATION OF HERBARIUMS. 127 



SECT. VI. Of forming and preserving Herbariums. 



579. Dried plants far surjiass either draivings or descriptions in giving complete ideas of 

 their appearance. When plants are well dried, the original forms and positions of even 

 their minutest parts, though not their colors, may at any time be restored by immersion 

 in hot water. By this means the productions of the most distant and various countries, 

 such as no garden could possibly supply, are brought together at once under our eyes, 

 at any season of the year. 



580. The mode or state in which plants 'are pi-eservcd, is generally desiccation, accom- 

 panied by pressing. Some persons, Sir J. E. Smith observes, recommend the preservation 

 of specimens in weak spirits of wine, and this mode is by far the most eligible for such as 

 are very juicy ; but it totally destroys their colors, and often renders their parts less fit 

 for examination, than by the process of drying. It is, besides, incommodious for frequent 

 study, and a very expensive and bulky way of making an herbarium. 



581. The greater part of plants dry with facility between the leaves of books, or other paper, 

 the smoother the better. If there be plenty of paper, they often dry best without 

 shifting ; but if the specimens are crowded, they must be taken out frequently, and the 

 paper dried before they are replaced. The great point to be attended to is, that the 

 process should meet with no check. Several vegetables are so tenacious of their vital 

 principle, that they will grow between papers ; the consequence of which is, a destruc- 

 tion of their proper habit and colors. It is necessary to destroy the life of such, either 

 by immersion in boiling water, or by the application of a hot iron, such as is used for 

 linen, after which they are easily dried. The practice of applying such an iron, as some 

 persons do, with great labor and perseverance, till the plants are quite dry, and all 

 their parts incorporated into a smooth flat mass is not approved of. This renders them 

 unfit for subsequent examination, and destroys their natural habit, the most important 

 thing to be preserved. Even in spreading plants between papers, we should refrain 

 from that precise and artificial disposition of their branches, leaves, and other parts, 

 which takes away from their natural aspect, except for the purpose of displaying the 

 internal parts of some one or two of their flowers, for ready observation. The most 

 approved method of pressing is by a box or frame, with a bottom of cloth or leather, 

 like a square sieve. In this, coarse sand or small shot may be placed, in any quantity. 

 Very little pressing is required in drying specimens ; what is found necessary should 

 be applied equally to every part of the bundle under the operation, and this can only be 

 done by the use of an equalising press of granulated matter, of compressed air, or of a 

 bag of water. 



Dried specimens are kept in herbariums in various ways : sometimes loose between leaves of paper ; at 

 other times wholly gummed or glued to paper, but most generally attached by one or more transverse slips 

 of paper, glued on one end and pinned at the other, so that such specimens can readily be taken out, 

 examined, and replaced. On account of the aptitude of the leaves and other parts of dried plants to drop 

 off, many glue them entirely, and such seems to be the method adopted by Linnaeus, and recommended 

 by Sir J. E. Smith. " Dried specimens," the professor observes, " are best preserved by being fastened, 

 with weak carpenter's glue, to paper, so that they may be turned over without damage. Thick and heavy 

 stalks require the additional support of a few transverse strips of paper, to bind them more firmly down. 

 A half sheet, of a convenient folio size, should be allotted to each species, and all the species of a genus 

 may be placed in one or more whole sheets or folios. On the outside of the latter should be written the 

 name of the genus, while the name of every species, with its place of growth, time of gathering, the finder's 

 name, or any other concise piece of information, may be inscribed on its appropriate paper. This is the 

 plan of the Linnasan herbarium." 



In arranging dried specimens, the most simple and obvious guide is that of the order of their flowering, 

 or that in which they are gathered, and this may be adopted during the summer season ; but afterwards 

 they ought to be put into some scientific method, either natural or artificial. They may be kept in a 

 cabinet, consisting of a collection of drawers for each order ; and the relative as well as absolute size of 

 these drawers, will depend on the proposed extent of the collection, as whether of British plants only, of 

 hardy plants only, or of all plants introduced to this country. In the chapter on vegetable geography will 

 be found data for the size of the drawers under every case. 



The fungi cannot in general be dried so as to retain the habit and character of the vegetating plant ; 

 but this defect is supplied by models, of which excellent collections are prepared for sale by the Sowerby 

 family, well known for their botanical works. 



The perfect preservation of an herbarium is much impeded from the attacks of insects. A little beetle, 

 called Ptinusfur, is more especially the pest of collectors, laying its eggs in the germens or receptacles of 

 flowers, as well as on the more solid parts, which are speedily devoured by the maggots when hatched, and 

 by their devastations, paper and plants are alike involved in ruin. The most bitter and acrid tribes, as 

 euphorbia, gentiana, primus, the syngenesious class, and especially willows, are preferred by these vermin. 

 The last-mentioned family can scarcely be thoroughly dried before it is devoured. Ferns are scarcely ever 

 attacked, and grasses but seldom. To remedy this inconvenience, a solution of corrosive sublimate of 

 mercury in rectified spirits of wine, about two drams to a pint, with a little camphor, will be found per- 

 fectly efficacious. It is easily applied with a camel-hair pencil when the specimens are perfectly dry, not 

 before ; and if they are not too tender, it is best done before they are pasted, as the spirit extracts a yellow 

 dye from many plants, and stains the paper. A few drops of this solution should be mixed with the glue 

 used for pasting. This application not only destroys or keeps off' all vermin, but it greatly revives the colors 

 of most plants, giving the collection a most pleasing air of freshness and neatness. After several years' 

 experience, no inconvenience has been found from it whatever, nor can any dried plants be long preserved 

 without it. 



The herbarium is best kept in a dry room without a constant fire. Linnaeus had a stone building for his 

 museum, remote from his dwelling-house, into which neither fire nor candle was ever admitted, yet 

 nothing was more free than his collection from the injuries of dampness, or other causes of decay. 

 (Smith's Introduction, ch. 24.) 



