Apparatus- Compound microscope, stage micrometer, camera lucida, Drawing board ,chloral hydrate solution, glycerin , water , etc

Principle:

The mesophyll of the leaf in dicot leaves is divided into small portions by branching of the veins through the tissues. The small areas of the green tissue outlined by the veinlets are termed as vein-islets.Vein –islets number is defined as the number of vein islets per sq. mm of the leaf surface midway between the midrib & the margin. It is a constant for the given species of plant & is used as a characteristic for the identification of allied species Levin in 1929. Determined vein islet number of served dicot leaves vein-let termination number is veinislet per sq.mm of the leaf surface midway between midrib & margin . A vein termination is the ultimate free termination of veinlet. It all & Melville in 1951 determined veinlet termination number of distinguishing between Indian & Alexandrian senna.

Procedure:

1. Boil few leaves in chloral hydrate solution in a test tube placed in a boiling water bath if the leaves are difficult to clear in this manner soak them in water treat successively with chlorinated soda for bleaching 10% Hcl for the removal of calcium oxalate & finally chloral hydrate solution.

2. Mount the preparation in glycerin water.

3. Set up the camera lucida & divide paper into squares of 1 sq.mm by mean of stage micrometer.

1. Replace stage micrometer by cleved leaf preparation & toace the veins in & continuous squares either in a square of 2mm×2mm or rectangle of 1mm ×4mm

2. Trace the vein islets & vein termination by looking through the microscope when a superimposed image of the leaf portion & paper is seen at the same time.

3. Count the number of vein islet & vein termination present within the square or rectangle & also by any two adjacent sides of the square or rectangle.

4. Divide the total number of vein islets & veinlet termination number in four adjoining squares by & in order to get value of 1 sq. mm .

5. Record the observation in the form of range & also indicate the mean value.