(1 



} 



I 



When seedlings have 

 the tips removed. 



^ 



a 



II 



If the removed tips A 

 are 

 immediately 

 replaced, 



they 



stop 



growing 



the seedlings 

 continue 

 to grow 





If there is a water-soluble 

 growth substance in the tip, 

 it will be absorbed by agar 



^s$a 



i,|o 



When plain agar and 



treated agar blocks 



are placed on beheaded 



seedlings, 



A 



Grox^rth substances absorbed 

 by agar will be reabsorbed 

 by the beheaded seedlings 



Will plain agar affect 



the growth of 



beheaded plants? 



GROWTH SUBSTANCE 



How can we tell that there are special growth substances? Experiments show that 



a substance formed in the tip of the shoot stimulates the growth of the plant 



