BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [18] 



thin papers is added, and this process is continued until all the plants 

 are changed from wet to dry papers. 



"No amount of curiosity should tempt you to remove the upper white 

 [thin] paper to look at a specimen. After a plant has been placed be- 

 tween thin papers, it should never again be in the least disturbed until 

 it is fully dry. The access of the air and the separation of the leaves 

 and flowers from the intimate contact which pressure gives them with 

 the thin sheets deaden the lively color which the plants otherwise will 

 preserve, and injure the specimens." (Ward.) 



Sticky plants or seeds may be prevented from adhering to the papers 

 by a liberal powdering of lycopodium spores or soapstone powder. Small 

 pieces of oiled paper placed over adhesive fruits may often be practiced 

 advantageously. 



CACTACEJ5 (cactuses.) 



"Living cacti bear transportation well if young or medium-sized 

 specimens are selected. The entire plant, or, if large, a joint or cut- 

 ting, is thrown in the shade for a few weeks to shrivel, after which the 

 specimens are wrapped in dry hay or moss and loosely packed in well- 

 ventilated boxes. 



" Treated in this way they preserve their vitality for from 6 to 16 

 months. Seedlings are easily raised from'seeds thoroughly dried and 

 packed in situ. If the fruit is large and pulpy it is sliced to facilitate 

 the drying, and should be kept from moistu re, but exposed to a free 

 circulation of air. 



" Herbarium specimens are best made by removing the flowers from 

 the plant and pressing them separately in the ordinary way, after first 

 sectioning some ot them. 



" When not too large the fruit may be dried in the same way, other- 

 wise it is halved and excavated before being put in press, the seed 

 being air-dried. The entire stem if small, or characteristic joints if it 

 is compound, may be pressed till dry after allowing it to shrivel, or if 

 it is too large for this, a piece is removed showing the top, the insertion 

 of several bunches of spines and of the flowers, and some of the tuber- 

 cles or ribs. Sometimes it is necessary to split and excavate these 

 specimens, and cross-sections dried under light pressure are desirable. 

 If the means of transportation permit, entire plants or well-selected 

 parts are rough-dried without pressure. These * skeletons,' preserved 

 in boxes in the herbarium, are often more instructive than the more 

 ornamental pressed fragments. When possible, it is also desirable to 

 make alcoholic specimens of the flower and fruit. 



" Oacti are at best poorly preserved for the herbarium, and should 

 always be accompanied by the fullest possible notes and sketches made 

 on the spot. Aside from the usual notes of locality, habitat, date of flow- 

 ering, and period of fruit ripening, others should betaken upon the fol- 

 lowing points : In the trunk note habit, presence or absence of aerial 



