-102- GROWTH. 



72. Effect of light on growth. 



(a) Seedlings grown in light and in darkness. 



(6) Adventitious roots formed only on the shaded side of an ivy stem. 



73. Influence of the whole plant on the growth of parts. When the terminal 

 bud of a stem is removed a lateral bud develops to form a new growing-point. 



74. Regeneration. 



(a) An isolated piece of willow stem showing the development of the lateral buds 



and of adventitious roots at the lower extremity. 

 (6) Eegeneration of the whole plant from an isolated leaf of Begonia. 



