INFLUENCE OF EXTERNAL CONDITIONS ON GROWTH 



239 



N 



B 



Fig. 122. — Two branches of broom. Genista anglica. C, 

 grown in dry air; B, in moist air. 



B 



Fig. 121. — ^Leaves of Tarax- 

 acum. A, grown in very imoist 

 atmosphere (actual length about 

 60 cm.). B and B', grown under 

 usual conditions (actual lengths 

 about IS and 12 cm., respectively). 



E I m 



Fig. 123. — Sempervivum. I, normal; II, grown in moist 

 air; III, grown in darkness. 



