EXERCISE 10. TO STUDY THE GROWTH RATE OF 



PLANTS 



Equipment; A home-made measuring device similar to 

 the one shown in Fig. 7; a corn or bean seedHng growing 

 in a pot or tumbler. 



Fig. 7.^ — ^A Simple Device for Measuring the Growth Rate of Plants. 



Method : By means of a light cord attach the tip of the 

 leaf or the end of a growing stem to the short end of the light 

 lever arm as shown in the drawing. Since the lever arm to 

 the right is eight times as long as the end attached to the 

 plant, an elongation of one inch in the plant will permit the 

 long end of the pointer to drop a distance of eight inches on 



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