OF THE FERNS AND FLOWERING PLANTS. 105 



will meet with numerous plants, belonging principally to 

 the family Crassulacese, such as Sedums and Sempervivums, 

 which are so succulent and so tenacious of life, that they 

 continue to grow after they have been laid between the 

 sheets of drying paper. These require a special treatment 

 of their own in order to destroy their vitality before any 

 attempt is made to preserve them for the herbarium. To 

 this end they are to be placed between two or three sheets 

 of paper, the inflorescence alone projecting beyond it, and 

 a hot iron is then passed over them. Two special pre- 

 cautions must be taken during the operation ; one, that 

 the flowers are not singed— the other, that the papers are 

 changed more than once, as the plants being always of a 

 succulent nature, a large amount of water is discharged by 

 the heat. 



There are some plants the "surface of which is coated 

 with a glutinous matter, which causes them to cling to the 

 paper, especially when under pressure : indeed, some of the 

 foreign Semperviva combine both these unpleasant con- 

 tingencies, extraordinary vitality and extreme viscidity. To 

 obviate the latter, the best plan is to sprinkle the specimen 

 with the spores of Lycopodium clavatum — to be procured at 

 most chemists under the name of l Lycopodium.' The spores 

 can be shaken off as soon as the plants are thoroughly dry. 



Delicate water plants are often difficult to deal with, as 

 their long trailing leaves and stems are apt to get hopelessly 

 interwoven at the moment they are taken out of their 

 native element, and it is an almost impossible task to 

 separate them after they are dried. Such plants must be 

 treated in the same way as was recommended in the case 

 of the filamentous Alga?, viz. passing under them, while 

 still in water, the paper, on which they are to lie. 



There are certain terrestrial plants, also of a fragile 

 perishable nature, which must be laid at once between 

 pieces of blotting-paper and not again disturbed until the 

 whole process of preparation is concluded. 



The packets of paper,, between which the specimens are 



