Aim: To observe the cell structures of an onion peel under a compound microscope.
Apparatus and Materials required:
1. Onion
2. Forceps
3. Class slide
4. Watch glass
5. Iodine solution
6. Coverslip
7. Mounting needle
8. Compound microscope
All living things are made up of cells. Cells are the building blocks of life. The shape, size and number of cells vary across different organisms.
Cell has three significant  components.
1Cell membrane
2. Cytoplasm
3. Nucleus
In-Plant cell, a cell wall surrounds the cell membrane.  
Steps are followed to the experiment:
  • Take a small piece of onion pulp, and peel it off from its concave side (inner layer).
  • Then put it in a watch glass containing water (to prevent the peel from getting folded or getting dry).
  • Take a class slide, put a drop of water on it and transfer the onion peel to the slide (make sure the peel is perfectly flat on the slide).
  • Put a drop of iodine solution on this piece followed by a coverslip (avoid air bubbles while putting the coverslip with the help of mounting needle).
  • Now observe under the compound microscope.
Onion cell under a microscope
You can see large, rectangular interlocking cells and observe visible cell wall, nucleus, large vacuoles, and some granules.