PLATE 22 



A. — Chilled and unchilled plants of wild crab, Malus coronaria. The plant at the 

 left had been outdoors during the fall and winter, leafless and dormant, exposed to 

 the frost and cold . The plant at the right had been in the warm greenhouse during the 

 fall and winter at a temperature of 55 to 70 F. When the outdoor, chilled plant was 

 brought into the greenhouse in early spring, it promptly began to put out new leaves 

 and twigs, but the indoor, unchilled plant continued its dormancy. The photograph 

 was taken April 24, 1917. 



B. — Blueberry plant with one branch stimulated to growth by cold. The right- 

 hand branch has been stimulated to growth by chilling; the left-hand branch has been 

 kept dormant by heat. For a detailed description of this experiment see p. 152-153. 



