|Biology Demonstration Manual (Peace Corps, 1993, 35 p.)|
Lesson: La nutrition des plantes
Rationale: Use onion epidermis to show stomates with a microscope.
Start 3 weeks in advance.
1. Put an onion in a glass of water so that the roots are submerged in water.
2. Let grow in the dark.
3. Roots will develop first and after about two weeks leaves should sprout
4. After leaves sprout, allow to grow another week. (At this point the onion can be planted in soil if it is not yet needed.)
5. Pick a short piece of leaf.
6. Peel the fleshy part away from the inside to leave the epidermis.
7. Mount the transparent epidermis on a slide with a drop of water.
8. Cover and observe with a magnification of at least 1 60x.
Optional: instead of growing the onion as described above, onion seeds are available in Bangui at Bamag, Dias or Cedox.
Source: Belin Sciences et Techniques Biologiques 6, p. 55, 90.