Author Institution: Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio 4522

Seidman, Gabriel

The Ohio Journal of Science

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590 JOSEPH J. KLINGENBERG AND HONG ZOON KIM Vol. 66EMBEDDING PLANT MATERIAL IN LIQUID SYNTHETICRESIN1 • 2—Plant material can be encased by embedding directly in liquid plastic,but the process consumes a great deal of time because of the necessity of killingthe tissue prior to embedding it. Leaf tissue is especially difficult to embed inplastic because killing in FAA (formaldehyde, alcohol, acetic acid) that containscopper sulfate is required (Nelson, personal communication, 1963). In additionto introducing artificial coloring in the tissue, the process takes several weeksand would not be adaptable as a field method.Another procedure, using tissue that has first been dried in silica-gel (GeneralBiological Supply House, 1963, Turtox Service Leaflet No. 33), allows retentionof natural color and shape, but when embedded directly in the plastic, the tissuedevelops cleared patches because of the action of the plastic upon the tissue.Thus, it would be impractical to use such a method to embed leaf tissue injuredby pathogens, insects, or air pollutants; the symptoms could become confusedwith artifacts caused by the embedding procedure.A relatively fast, simple, and non-injurious method has been developed for theembedding of dried leaf tissue in plastic. Dry the tissue in powdered silica-gel in apan for 36 to 48 hours and protect the leaf tissue between a layer of "Permafilm"(Denoyer-Geppert, Chicago, Illinois)3 adhesive and clear 1 mil Mylar before em-bedding in the plastic. During periods of high relative humidity, drying can be'Contribution from the Soil and Water Conservation Research Division, Agricultural Re-search Service, USDA, in cooperation with the Laboratory of Medical Biological Sciences,Division of Air Pollution, Public Health Service, HEW.2Manuscript received December 8, 1965.3Trade names and company names are included for the benefit of the reader and do notinfer any endorsement or preferential treatment of the product listed by the U. S. Departmentof Agriculture or the Public Health Service.THE OHIO JOURNAL OF SCIENCE 66(6): 590, November, 1966.No. G EMBEDDING PLANT MATERIAL IN PLASTIC 591accomplished in a desiccator or other container that can be tightly closed. Theleaves need not lie absolutely flat when drying in the silica-gel; thus, the naturalundulations of the leaf material can be preserved. Air spaces in the envelope en-casing the tissue do not show up over the blade although an air space may benoticeable around the leaf margin. After the leaf is anchored on the "Permafilm"adhesive (lower layer), the edges of the "Permafilm" are folded over the top layerof Mylar. This is imperative, because the "Permanlm" adhesive dissolves slowlyin the liquid plastic. If the "Permafilm" is not folded over the Mylar, the plasticenters the envelope and blemishes the leaf tissue before the plastic solidifies.Another variation is to envelope the specimen in Mylar and seal the edges withclear plastic ("Scotch") tape before embedding.Plastic of a type that dries completely through to the surface (Turtox Embed-ding Plastic, General Biological Supply House, Chicago, Illinois) is prepared accord-ing to the manufacturer's instructions, and the specimen to be embedded is placedin the liquid plastic with a sliding motion to avoid trapping air bubbles beneaththe specimen. The best mold in which to make a casting is an aluminum cakepan coated with mold release compound.The plastic is allowed to solidify, and a covering layer of plastic is added.When the plastic block is cured and removed from the mold, it is trimmed to re-move the overlapped edges of the envelope. The trimmed edges of the block aresealed by rubbing with ethylene dichloride. If the procedure is carried out in thefield, the casting can remain in the mold until it is returned to the laboratory forcuring.For certain needs, this method is better than traditional herbarium methodsfor preserving plant material, because the encased specimen can be handled in-numerable times without fear of destruction and the natural colors of mostspecimens are preserved. In addition, the process is simple enough to be ac-complished in the field if the collector is to be away from laboratory facilities forany length of time, GABRIEL SEIDMAN, Robert A. Taft Sanitary Engineering Center,Cincinnati, Ohio 45226.

Embedding Plant Material in Liquid Synthetic Resin

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Embedding Plant Material in Liquid Synthetic Resin

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