THE GROWTH OF THE PLANT 



93 



Experiment 59 . 



Aim. — To find out whicli rays of light have the 

 greatest influence in determining the direction taken 

 by the different parts of the plant. 



Method. — The three boxes prepared for Experiments 

 31 and 57 can be used again in this investigation. The 

 two, which are respectively fitted with sheets of red 



Fig. 45 



and blue glass, are ready for use. In the third box the 

 cover must be replaced by a sheet of plain glass. 



Three tumblers are almost filled with water. A piece 

 of coarse net is put over the top of each and kept in 

 place by a rubber band. Damp sawdust or fibre is 

 placed over the net, and on this mustard seeds are 

 sprinkled. 



One of these tumblers is then put into each box and 

 the boxes are placed in a good light. 



Observations. — In every case the shoots of the 

 seedlings grow towards the light and the roots away 



