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 - 1. Place blotting paper in the bottom of each of four Petri dishes. Moisten the paper, but be sure that it is not floating in water. Sprinkle about 40 tobacco seeds evenly over the surface of the paper. Keep the seeds a few seed lengths apart from each other.
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2. Replace the covers of the dishes and place the dishes in a well-lighted place, but not in the direct sunlight. The temperature should be approximately 22°C.
- 3. Cover two dishes with a lightproof container.
- 4. Leave the other two dishes exposed to the light.
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5. Let the seeds germinate for about a week, adding a few drops of water to the paper every other day or whenever the paper begins to dry.
- 6. On the tenth day, begin to make entries in your table of results.
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a) Make up tables on which to record your results. You may wish to use tables similar to the ones shown on the next page.
- b) Every day, record how many and what kind of seedlings you observe.
- 7. When all or most of the seeds have germinated in the darkened dishes (probably the twelfth day) remove the covering. Place these dishes in the light next to the others.
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a) Continue to record the appearance of the seedlings through the thirteenth day.
- 8. Study all the data you have accumulated.
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a) Try to draw any conclusions that you can from your data.
- 9. Using your data for the seedlings that were kept in the light all the time, answer the following questions:
- a) How might you explain the differences you observed?
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b) Are these differences caused by heredity or environment?
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