PRESERVATION. 53 



have not been figured in detail; the figures given 

 will, however, serve to guide the observer in tneir 

 recognition. 



Preservation. The ferns may be easily preserved 

 in the entire state, by laying them flat between sheets 

 of coarse unsized paper, and subjecting them to mode- 

 rate pressure in a screw-press; the paper should be 

 changed, or dried before a fire every two or three days, 

 and the pressure repeated until the specimens become 

 dry and rigid. They may then be mounted on sheets 

 of paper, being fastened eitherwith thread passed round 

 the stalk or portions of the frond with a needle, and 

 tied in a knot behind, or with strips of paper gummed 

 at the ends. 



The minute structures may be preserved either in 

 the dry state or in glycerine. 



r3 



