OF THE LICHENS. 
137 
over, and, when necessary, again damped and softened. 
They should then be spread out between sheets of blotting- 
paper, so as to exhibit as near as can be their original 
character, and left to dry under a light pressure. On 
the whole, the Lichens cause less trouble in their pre- 
paration than any other group of plants, except perhaps the 
Mosses. 
In the case of certain small species (as, for instance, 
Boeomyces roseus) which grow on the earth, the better 
plan when collecting them is to carry away with the plant 
a thin layer of the soil itself. This is easily effected by 
means of a knife. In the same way all such as flourish on 
wood, tree stems, palings, &c., should, on being taken off, 
retain a very thin section of their support. The difficulty 
of gathering those which are firmly fixed to the face of a 
rock, overgrowing it like a thin crust, is far greater, as the 
stone itself must be chipped off with chisel and hammer. 
Of course the difficulty is increased where the operator has 
to deal with the smooth surface of a compact rock ; as, on 
the other hand, it is considerably lessened when the material 
is of a calcareous, slaty, or schistose character. Each piece, 
on being broken off, must be wrapped separately in paper, 
to prevent them from rubbing against one another, thereby 
spoiling the incumbent Lichen, or at least destroying its 
fruit. 
I take this opportunity of cautioning the botanical novice 
against preserving only such small specimens of the chipped- 
off rock as will lie between the sheets of his herbarium ; 
an error he is liable to fall into for the sake of uniformity 
and for convenience of arrangement. He forgets that, as 
time goes on and his collection increases, it must of 
necessity be divided into numerous smaller portions, and be 
put away in drawers or boxes. He had, therefore, much 
better at once secure good instructive examples, even 
though he is obliged to keep them in separate repositories, 
than have to do his work over again at a future period. 
I need scarcely perhaps add that, with Lichens, as with 
