AND DRYING THE PLANTS. 



23 



and sheets of drying-paper interspersed between each 

 layer, the whole is to be removed to one of the square 

 pieces of deal ; whilst another piece is to be placed on 

 the top, and immediately subjected to a certain amount 

 of pressure. When there are but few specimens, and 

 these of the finer varieties, one or two books, or a flat 

 stone, will be quite sufficient for this purpose ; but, 

 should there be a large quantity, and these happen to 

 be of a coarser description, a screw-press is necessary, 

 the proper amount of force required being readily 

 ascertained by a little practice. Great caution, however, 

 must be observed, that the pressure is not too severe, 

 as the specimens would not only be liable to be injured, 

 but the impression of the threads of the calico would be 

 visible, and give them an unsightly and unnatural ap- 

 pearance. As a guide to the young algologist, and to 

 prevent such a result, it should be remembered that it 

 is best to commence at first, when the plants are wet, 

 with a very slight degree of pressure ; and to increase 

 it gradually as they become nearly dry, when any 

 amount of pressure may be used to advantage. 



In about two or three hours' time, the wet layers of 

 drying-paper should be removed, which must be done 

 very carefully ; but on no account must the pieces of 

 calico be disturbed until the specimens are dry, and 

 fresh folded sheets of the finer sort of drying-paper sub- 

 stituted in their place. Additional layers are to be 



