s8 British FniiQi. 



localities, or different stages of development^ will pro- 

 bably be obtained^ and it is convenient to have all the 

 specimens of one species together, and in some vari- 

 able species, two or more sheets of specimens may be 

 necessary to illustrate the sequence of forms. All the 

 species sheets of a genus should be enclosed in a 

 genus cover or folded sheet, with the generic name 

 written outside. The arrangement of specimens in 

 the herbarium must be such as to enable any given 

 species to be found without loss of time, and this is 

 best accomplished by adopting the alphabetical ar- 

 rangement. The genera of each family should be 

 placed in alphabetical order, and the species of each 

 genus similarly arranged. The herbarium must be 

 kept in a dry place, otherwise the specimens will soon 

 be covered with mould, as many species, even after 

 being thoroughly dried in the first instance, become 

 soft and absorb moisture in damp weather. To guard 

 against the attacks of minute beetles the specimens 

 are sometimes treated with a solution of corrosive 

 sublimate in methylated spirit, but this is an objec- 

 tionable method, as the sublimate is left in the form of 

 a whitish bloom on the surface of the specimen after 

 the spirit has evaporated, and furthermore, does nut 

 destroy the beetles in woody specimens of the Poly- 

 2)ore8e, &c. A better remedy is to expose the packets 

 to the fumes of carbon disulphide for two or three 

 days in a closed box, but in a small collection that is 

 constantly under supervision, a little camphor placed 

 in the box or cabinet with the specimens is generally 

 fiufiScient. The value of a collection in the eyes of 

 some people depends on the number of specimens it 



