Equipment for Working with Lumbriculus variegatus
Dawn Hancock and Paul Kelly
The following directions for making your own equipment is from Dr. Charles Drewes of Iowa State University.
Make a rubber band widget and hair widget from applicator sticks, thin rubber band, and tape as shown in the following figure: Make sure that the rubber band is straight, extends about 1/2" beyond the tip of the stick, and is cut at an angle at the tip. You should use only the hair or rubber band widgets to touch the worm in procedures in which the worm must be manipulated.
Making Parafilm Well Slides for Viewing Lumbriculus :
new single-edge razor blades
parafilm (4" X 125 roll)
plain glass microscope slides (precleaned 25 X 75 X 1 mm)
flat-topped, metal surfaced hot plate
sharp tipped permanent pen
glass plate (approximately same size as hot plate surface)
clean, light-weight gloves
glove for handling hot objects
fine tipped, sharp forceps
slide box for storage
1. Turn on the hot plate to low.
2. Cut off equally sized, large sheets of Parafilm (4" X 6"). Remove the backing from each, making sure the sheets are not wrinkled or stretched.
3. Lay out a tight array of eight slides on the glass plate. The array should be nearly the same size as the Parafilm sheets and slightly smaller than the glass plate.
4. Neatly stack the Parafilm sheets on top of one another and place them on the array of slides making sure all corners are in alignment.
5. Make sure the glass plate is on a smooth, flat surface, such as a counter top. Then, working from the middle and with your finger tips, press the Parafilm sheets down against the glass slide to get them flattened out, and adhering to each other and to the slides, as much as possible before heating.
6. Transfer the glass plate and slides to the surface of the hot plate and let it warm up for about 5-10 minutes. When properly heated the Parafilm should just begin to get slightly clear and soft, but not melted. Do not overheat Parafilm and do not leave these materials on the hot plate unattended.
7. As the Parafilm heats, find several sheets of leftover Parafilm backing. Place these on the Parafilm and, with gloved hands, begin pressing the softened Parafilm against the glass slides. Try to work out air bubbles in the Parafilm, making sure the layers are adhering to each other and to the glass slides.
8. Using a glove for handling hot objects remove the glass plate with the slides and place it on the counter top. Let it cool.
9. Using a new single edged razor blade and a metal ruler for alignment, make cuts through Parafilm as shown in the illustration below. Carefully separate each slide.
10. Next make the trough cuts through the Parafilm on each slide. Make sure to extend the cuts slightly beyond the trough dimensions, otherwise it will be difficult to remove the
center piece from the trough.
11. Finally, use the forceps to remove the center piece from the trough.
12. If any part of the trough becomes loosened from the slide while cuts are being made, briefly reheat the slide on the hot plate to re-establish contact between the Parafilm and slide.
13. Store slides in a slide box or other storage container.
About The Authors:
Dawn Hancock, Biology Teacher
P.L. Dunbar High School
5700 Ramey Avenue
Fort Worth, TX 76112
Paul Kelly, Biology Teacher
Park Hill High School
7701 Barry Road
Kansas City, MO 64153