Figure 1, Parts A-E. Conical wells and their use in preparing pollen for CSEM.
Part A. Diagrams of conical wells made from drilled-out CSEM specimen holders.
Part B. Pollen in dehydration fluid (EtOH, Peldri-II, HMDS, etc.) is dripped from pipette into conical well.
Part C. After evaporation of dehydrant, dry pollen is dispersed on the sides and bottom of the well. The large surface area enhances speed of pollen drying and increases the number of well-preserved grains.
Part D. Pollen is concentrated in well bottom by freeing adherent grains from highly polished well with an eyelash stick. In order to obtain maximum transfer of pollen, we routinely brush the entire well area to free the pollen and then gently "tap" the well to concentrate the sample. This procedure, in conjunction with the highly polished surface, guarantees essentially 100% transfer of pollen without typical loss due to sticking to side walls.
Part E. The concentrated and loosened pollen is transferred to a CSEM specimen holder covered with an adhesive [not shown in diagram but consisting of carbon tape, Tempfix (7), silver paste, etc.].
Inset: The X's crossed through each figure summarize some problems encountered when transferring dry pollen using standard laboratory containers. Top and middle insets- with test tubes and pipettes, drying is less than desirable because: (a) fumes released from dehydrant must travel considerable distances along the sides of the glass tubes, which markedly increases drying time, and (b) dry pollen is difficult to free from the sides of the glass vessels. Bottom inset - when air or chemical drying is done directly on CSEM specimen holders pollen is frequently highly dispersed and difficult to locate with the CSEM and, as discussed elsewhere (6), often unstable.