OF THE FERNS AND FLOWERING PLANTS. 165 
will meet with numerous plants, belonging principally to 
the family Crassulaceas, 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 Lycopodiiun clavatum — to be procured at 
most chemists under the name of f 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, aiso 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 
