38 MISC. PUBLICATION 56S, U. S. DEP'T. OF AGKICULTUBE 



be removed. Some fleshy plants, like cacti or pineapples, may require 

 as much as 2 weeks. When artificial heat is used, perhaps the examina- 

 tion should be made twice a day to guard against overdrying. 



Good specimens should be entirely flat when dry: for that reason, the 

 ropes on the presses must be tightened from time to time in order to 

 maintain a constant pressure on the plants. With artificial heat, the 

 ropes should be tightened at the end of 3 or 4 hours and at regular inter- 

 vals thereafter. Plants dried under insufficient pressure will produce 

 unsightly, practically worthless specimens, because the leaves and 

 flowers will become shriveled and the stems distorted. Such material. 

 also, is apt to shatter in shipment and, furthermore, causes great trouble 

 in the final mounting. 



For various reasons, it is important that the plants remain in the 

 paper folders in which they were dried. The folders of dried plants can 

 be kept in a convenient place until the entire lot has been completed. 

 The piles should be weighted down or tied with a string as a precaution 

 against accidents. A sudden gust of wind can ruin the labor of many days. 

 Dried specimens should be protected overnight against the ravages of 

 ants, cockroaches, mice, and other pests. Later the collections are sorted 

 numerically and stored away for final disposition. To expedite handling 

 and to avoid confusion, all duplicate sheets of a collection number should 

 be kept together. This is best clone by using one sheet as a cover with the 

 extra ones inserted so that all can be handled as a single unit. Constant 

 care is needed to prevent the contents of the sheets from sliding out. 

 but usually the plant will have adhered slightly to the sheet during the 

 drying process, and ordinary handling will not dislocate the specimens. 

 Some collectors feel that extra precaution must be taken and often 

 attempt in various ways to attach the plants to the sheet. The use of 

 adhesive tapes, or even glued-paper strips, is to be discouraged as a 

 waste of time, both for the collector and for the person who must finally 

 unstick the specimen. Adhesive tapes often leave a gummy deposit on 

 specimens, which is difficult to remove. 



In very humid climates, dried specimens will need protection against 

 absorbing of moisture from the air. Air-tight boxes are most desirable 

 for this purpose, but under field conditions some other means usually 

 must be sought. Most practical, perhaps, would be to carry along a 

 supply of waterproof paper with which to wrap the packages. The paper 

 must have a tough texture, however, and be large enough to allow gen- 

 erous overlapping at the ends of the package. 



Waterproof paper can be made by dipping manila paper in melted 

 paraffin. If paraffin is not available, waterproof paper can be made by 

 the following formula: 



Dissolve 1.8 lb. white soap in 1 qt. water. 



Dissolve 1.8 oz. gum arabic and 5.5 oz. dry glue in 1 qt. water. 



Mix the two solutions, dip manila. or similar, paper in mixture and then allow it 

 to dry. 



The standard practice has been to add a small quantity of either 

 naphthalene or paradichlorobenzene (Paracide) to each package before 

 shipping or storing. Naphthalene flakes are best for sprinkling over the 

 specimens. These substances give some protection against attacks of 

 insect pests, and some people believe that they also check the develop- 

 ment of molds. 



