Lab Protocols

Experiments for the Teaching Lab

Making Simple Tools for the Developmental Lab

Dark Field and Rheinberg Filters for Microscopy

Special Supplies:

Figure 1

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Figure 8

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Figure 11

Figure 12

Procedure:

  1. Remove the normal filter from the microscope; it should be located just below the condensor (Fig. 1).
  2. Use this filter as a template to trace a circle on a clear transparency (Fig. 2) and cut out the circle (Fig. 3).
  3. Next cut a piece of black electrical tape and adhere it to small scrap piece of transparency. Use a ruler and pen to mark a circle 1.5 cm in diameter on the tape (Fig. 4) and carefully cut along the line (Fig. 5).
  4. Peel the circular piece of electrical tape off of the scrap transparency and position it in the center of the first circular transparency cut-out (Fig. 6).
  5. Done with dark field filter!
  6. To make the Rheinberg filter re-trace the day-light filter on a light shade of colored transparency (any light color may be used) and cut out as before (Fig. 7).
  7. Trace an additional concentric (sharing the same center) circle on this cut-out about 0.7 cm in diameter. Trim out this inner circle to make a donut shape (Fig. 8).
  8. Cut out two identical circles 1 cm in diameter from a dark shade transparency and the address label (one circle from each) to give you three separate pieces (Fig. 9).
  9. Assemble the Rheinberg filter in the following manner: light shade transparency (donut-shaped) in the middle, dark shade transparency on one side, and the address label on the oppossite side (sticky side in) (Fig. 10). The adhesive address label holds all of the pieces together.
  10. You are now done (Fig. 11)! Replace the normal daylight filter along with your filter of choice (Fig. 12) and enjoy. Figure 13 shows a bee stinger under these two filters (courtesy of Eric Cole).

Figure 13

Cactus Spine Dissection Tool

Special Supplies:

Figure 1

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Procedure:

  1. Obtain a small wooden probe and use a single-edge razor blade to saw/carve a notch in one end about 0.5 cm deep (Fig. 1).
  2. Use forceps and scisors (if necessary) to pluck a medium size spine from the cactus plant (Fig. 2).
  3. Grasping the loose spine with the forceps, insert the blunt end into the groove on the wooden probe (Fig. 3). You can insert the spine at various angles to produce a variety of tools for which may be better suited for certain situations.
  4. Brush Liquid Skin all around the tip of the probe to hold the spine in place (Fig. 4).
  5. Done (Fig. 5)! These nifty needles can be used for sectioning organisms during regeneration experiments, chick embryo surgeries, or wherever a fine, delicate point is needed.

Figure 5