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Type-SPIROGYRA NITIDA. 



Spirogyra is a freshwater alga found particularly 

 in ponds and springs, and may be recognised by its 

 bright green or yellowish colour, as well as by the 

 delicacy of its filaments. Each plant consists of a 

 single, cylindrical, unbranched, thread of cells. Each 

 cell wall is lined by a delicate, colorless, peripheral 

 layer of protoplasm, which becomes clearly visible 

 when the cell is treated with some water- withdrawing 

 medium (solution of common salt or glycerine). 



The chlorophyll takes the form of closely-wound 

 spiral hands having a finely undulating outline, 

 lying next to the protoplasm ; embedded in the 

 band are the amylum bodies, sometimes known as 

 pyrenoids. These are dense globular colourless 

 grains, each of which contains a protem crystal, and 

 is bounded by a hollow globe of small starch grains. 

 A nucleus occupies the centre of each cell, and in 

 some species exhibits the form of a bi-convex lens. 

 In the centre lies a nucleolus ; sometimes as many as 

 three nucleoli are present. 



The nucleus is surrounded by a very thin layer of 

 protoplasm, from which delicate protoplasmic threads 



