110 



press; but the pressure will have to be applied very gently at 

 first or they will be crushed. Excellent results may be obtained 

 in this way with the most recalcitrant material, particularly if 

 spirit be used; as the spirit can be used many times over no 

 great supply is required. 



Certain aquatic plants with limp stems and finely divided 

 leaves, as, for instance many Ranunculi and Utricularias, or 

 Algae with a much divided thallus, are very easily dried between 

 absorbent paper, but they cannot be spread out properly on a dry 

 sheet because they eollapse, when taken out of the water, into 

 shapeless tufts and bundles. They should be caught up on a sheet 

 of stiff paper under water, when they can be spread out easily, and 

 then by drawing the sheet slowly and slantingly out of the water 

 with the base of the specimens towards the operator they may be 

 fixed on the paper in their proper position and placed in the 



retainer " where they will dry rapidly with a moderate applica- 

 tion of pressure. 



Herbarium conditions. — The size of the paper on which the 



<c 



plants are mounted varies in different herbaria, but that in use 

 at Kew measures 16-| in. (42 cm.) by 10| in. (26-5 cm.), which is 

 rather smaller than that of most of the other large herbaria. For 

 large ferns, palms, screwpines, etc., a larger paper is sometimes 

 used, 21|- in. (54'5 cm.) by 14^ in. (36'5 cm,); but most col- 

 lectors with limited means of transport will have to fit their 

 presses to the smaller size. Quite a small-sized press can be used 

 where collecting is confined to small plants only, as, for instance^ 

 to mosses, or to the low herbs of arctic regions or high mountains. 

 Stress has repeatedly been laid on the necessity for selecting 

 representative specimens that exhibit all the parts of the plant as 

 far as this is possible within practical limits, and of preserving 

 them so as to allow of their subsequent external and internal 

 examination. 



For this purpose an ample quantity of flowers and fruits miist 

 be provided with the specimens, especially whei these organs are 

 small. This can generally be done quite easily, by drying an 

 extra supply of flowers and fruits and placing them in capsules 

 made of absorbent paper in the ^^ retainer " along with the speci- 

 men and giving them the number of the specimen. But the 

 collector who wishes to assist the herbarium worker to the full 

 should cut open or divide lengthwise at least some of those 

 flowers which he intends for the supplementary capsules, and dry 

 them flattened out. The same applies to certain compact 

 infloreiycences, such as the ''heads" of composites or the spadices 

 of Aroids, and to many fruits and infruetescences. Specimens 

 may be almost useless unless the collector proceeds in some such 

 way, as for instance, in the case of the Balsams, and still more, 

 of many Iridaceous, Zingiberaceous and Marantaceous flowers, 

 the parts of which become frequently quite inseparable and 

 indistinguishable when they are pressed whole. 



Drying in the air. 



It may sometimes be necessary to dry in the air certain speci- 

 mens or parts of specimens which are too bulky to be pressed 



