To prepare a temporary mount of onion cells. (LAB REPORT)

Aim: - To prepare a temporary mount of onion cells.

Materials Required:- Onion, Knife ,Forceps ,Blade ,Slides ,Watch glass ,coverslip ,brush, compound microscope, blotting paper, a clean piece of cloth,
Iodine solution, Safranine, Glycerine and water.

Introduction:- Onion is a plant that belongs to the genus allium.  Its binomial term is allium cape.  Commonly known as garden onion, the rounded edible bulb of the onion plant cultivated globally develops underground. The onion plant has hollow leaves and it should not be mistaken with tuber, which it is not.



Procedure:-

• Take a piece of onion scale and bend it towards the concave side until it breaks into two. When it breaks, it will be notice that a thin membranous structure still connecting the two bits. This membranous structure is called onion peel or epidermis.
• Carefully tear off one of the bits from the epidermis hold the freed epidermis with a forceps and peel it from the other bit.
• Take some water in a watch glass and put the epidermis in it Make certain that it is not folded or rolled.
• Add 1-2 drops of Iodine solution or Safranine solution.
• After about 2-3 minutes take the peel and wash in acid water if Iodine solution is used or in plain water if Safranine is used.
• Take a clean glass slide and put a drop of glycerine almost in the middle of the slide.
• Place the stained piece of the peel in the glycerine and put a cover slip on it.
• Soak the overflowing fluid from the corners of the coverslip with the help of the blotting paper and clean the side.
• Observe the wet mount under the low power of the microscope and then under high power

Observations:-

{Under Low power of the microscope} 

1. The rectangular cells of onion epidermis are seen. The regularly arranged components like cells have clear outline. In this case, the outlines are formed by rigid walls known as Cell Wall.
2. A deeply coloured, round body is seen in side every cell. This is known as Nucleus.

{Under the high power of Microscope}

1. Nucleus with Nucleolus is clearly visible.
2. A thin layer of less deeply coloured substance along the inner surface of cell wall is seen. It is called Cytoplasm.
3. The central part of the cell, interior to the cytoplasm takes very little stain, this portion is known as vacuole.