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, 

 Bceomyces 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 nourish 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 



