L20: Mitosis in an onion root.

• Material: microscope slide, coverslip, dropper, needles emmanegades, watch glass, beaker, fine tweezers, lancet, encenador and dad filter.
• Chemicals: aigua destil·lada, aigua corrent, orceïna A i orceïna B.
• Natural products: onions.
• Procedure:

1. Keeps several days a bulb onion on a glass full of water, so that the lower part of bulb where the roots emerge, in contact with water. To hold the onions can be three sticks nailed to utility bulb.
2. When the roots have grown about three centimeters, cut with scissors and place them end four millimeters in a crystal clock with two millimeters orceïina A.
   Then, heat it with the flame of a lighter until steam appears tenuous. It must ensure that during this process the temperature exceeds 60 ° C at any time.
   To check this, we constantly have to remove the glass clock above the flame and put it over on the back of the hand, which in no case should notice a burning sensation.
3. With fine tweezers, place one of the pieces of root on a slide and add a few drops of orceine B with dropper.
4. With the lancet, cut the two millimeters final piece of root and retira'n the rest. Put it on the coverslip and three or four strips of papaya filter. Then make it a slight pressure with the thumb, starting gently and then a little harder, trying not to break the coverslip in order to extend the cells.
5. Observe it with a microscope 600 increase (or preferably more). As luck you have, you will see cells in different phases of mitotic division.