V ] HERBARIUAl. 365 



changed, with the specimen undisturbed upon it, to the dry 

 sheets. Pasteboards, or, better still, " ventilators " (made 

 the size of the paper, of narrow strips of deal at short 

 distances apart, nailed together in two layers at right-angles 

 to each other, as shown in the cut. Fig. 241), may be intro- 

 duced at intervals between the layers of paper until the pile 

 be ready for the press, which may consist simply of two 

 stout boards, made so that they cannot bend or warp. 

 Between these boards the paper and specimens must be 

 placed, and a weight of stones or metal, not less than 

 50 lbs. or 60 lbs., laid upon the top. 



The papers should be changed, several times, once a day, 

 and then at longer intervals, until the specimens are quite 

 dry, when they should be removed from the press. If fresh 



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 Fig. 241. Ventilator. 



specimens be placed in the press, while others are in pro- 

 cess of drying, they must be carefully separated by paste- 

 board, or by a thick layer of paper. The length of time 

 which specimens ought to remain in the press varies with 

 their nature, whether dry or succulent, and with the kind 

 and quantity of paper used. Common stout brown paper 

 answers very well. It may be cut to any size, but, generally, 

 it should not be less than sixteen or eighteen inches long 

 by ten inches wide. Practice will soon suggest many little 



