14 MISC. PUBLICATION 679, U. S. DEPT. OF AGRICULTURE 



PRESERVING AND LAYING OUT THE SPECIMEN 



In carrying out this step there are three different procedures to chooj 

 from, and selection of the one to be employed depends upon the structm 

 and the preserving characteristics of the specimen material to t 

 processed. 



Procedure A can be used only for specimens in which natural cok 

 can be retained during pressing and drying. It can be employed for 

 wide variety of material and is the quickest and simplest to apply, bi 

 in many instances the results are not as satisfactory as those obtaine 

 with procedure B or C. 



Procedure B is primarily for use with material which consists only c 

 thin tissues and which cannot be satisfactorily dried in press or is to 

 complicated in structure to be suitable for laying out after treatment b, 

 immersion. It is especially applicable to specimens having unstabl 

 pigmentation which possess finely dissected leaves and complex ic 

 florescences; but it may also be used to good advantage in man; 

 instances for such material as algae, mosses, and liverworts, leaves 

 certain conifers, grasses, autumn foliage, and thin sections of fruit 

 and other succulent or woody material. 



Procedure C should be employed for material which cannot be pressec 

 satisfactorily and is of a thick or succulent nature which makes it unsuit 

 able for treatment by procedure B. It is also used for specimens tha; 

 have brittle or fragile parts which cannot be laid out properly befon 

 treatment or that have particularly unstable pigmentation which re 

 quires treatment with a considerable volume of preserving fluid in ordei 

 to inhibit color change. Procedure C may also be used, if desired, foi 

 various classes of specimens included under procedures A and B, and 

 while it is the most time consuming of the three procedures, it will ir 

 many instances yield the best results. 



After the appropriate preserving fluid and the most suitable methoc 

 of applying it have been determined for a given specimen the processing 

 procedure decided upon should be carried out in general accordance with 

 the directions given in the following sections. 



It will be found convenient to carry out the hand-processing parts oi 

 the work on a sheet of heavy glass approximately 12 by 18 inches in size 

 Adequate illumination is important, and the use of adjustable lights will 

 be found to be advantageous. Running water for washing hands and 

 implements is highly desirable, and the use of distilled water for rinsing 

 the implements will help in avoiding accidental contamination of one 

 preserving fluid by another. Cloth or preferably paper towels are 

 needed throughout the work. 



Procedure A — Drying Specimens Before Applying Preserving 



Fluid 



Preparing specimens for pressing. — Specimens to be preserved by 

 this procedure should after careful cleaning be pressed and dried, pref- 

 erably in a strap-type plant press provided with corrugated cardboard 

 ventilators and thin blotters and driers. In general, the blotters should 

 be used only when needed to protect the specimens from being marked 

 by the corrugations because they tend to retard the removal of moisture 

 when heat is applied. The specimens should be placed in folders con- 



