THE LIVING SUBSTANCE OF PLANTS. 



23 



Synopsis. — The spirogyra plant occurs in quiet water. 



f A single cell, cylindrical, is a section of a long thread. 

 Cell wall of cellulose. 



Chlorophyll band, flattened, coiled spirally around the inner side 

 of the wall, colored green by the chlorophyll substance. 

 Nucleus, granular, near centre of cell. 

 Spirogyra Small nucleolus within nucleus. 



cell. Protoplasm proper (cytoplasm) radiating in strands 



rrotoplasm. \ from the nucleus ; thin wall layer next the cell 

 wall. 

 Cell-sap (watery substance) occupying the spaces 

 between the strands of protoplasm. 

 (Starch masses in the chlorophyll band.) 

 The spirogyra thread is made up of many of these cells lying end to end. 

 Reactions of protoplasm in spirogyra: 

 Stains yellowish brown with iodine. 



A 1% aqueous solution of eosin does not stain the living protoplasm. 

 Alcohol kills the protoplasm, so that eosin will then stain it. 

 Materials. — Fresh mats of the pond-scum spirogyra, either freshly collected 

 from ponds or ditches, or from an aquarium where it may be kept for a week 

 or more in a fresh condition. 

 A solution of iodine. 

 A 1% aqueous solution of eosin. 

 95$ alcohol. 



Watch glasses for receiving the solutions when the pupils are engaged in 

 exercises II. Microscope, etc. 



