To assemble and set up a Baermann funnel to extract nematodes from soil:
Figure 16. Diagram of Baermann funnel for extraction of nematodes. (Courtesy C. Jasalavich).
NOTE: To see the body structure of a nematode in more detail, you will need to examine it with a compound microscope. Prepare a slide mount as follows. Place three or four drops of clear nail polish on a clean microscope slide so as to form the corners of a triangle or rectangle of a size that will support a cover slip (FIGURE 17). Do not add the cover slip yet. (Once your mount is completed, the nail polish supports will prevent your nematodes from getting crushed.) Next, use a Pasteur pipette or eyedropper to place a drop of water containing nematodes in the center of the dots. Warm this drop of water by passing the slide six to eight times over the flame of an alcohol lamp to relax the nematodes. You want to warm it just enough so that the nematodes stop moving, but not too much or the nematodes will burst; you can check the progress by looking at this slide under your dissecting microscope. After the nematodes have stopped moving, place the cover slip so that it rests on the nail polish supports. The edges of the cover slip should be sealed with clear nail polish to prevent the water underneath it from evaporating. Now it is time to look at your nematodes with a compound microscope.
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