GROWTH 



293 



liminary one, a stage of deep rest and a condition of forced rest, 

 which gradually and imperceptibly merge one into another. During 

 the preliminary stage, through which most buds pass in summer, 

 they may be readily returned to active life. This may be accom- 

 plished simply by removing the leaves. In some trees, as oaks and 

 elms, the buds frequently open in summer, even without special 

 treatment, and produce secondary growth (St. John's shoots). 

 In the fall, after the leaves have normally dropped, dormancy is 



Fig. 115. 



-Shoot of lilac. Right branch subjected to a warm bath, left one 

 remained untreated (after Duggar). 



in its deepest stage. At this time forcing requires particularly 

 strong stimulants. Towards late winter and early spring, buds 

 gradually leave the state of rest. When placed under conditions 

 favorable for growth, they will begin to unfold without any par- 

 ticular treatment. Since the absence of growth during this period 

 is not due to internal inhibition, the usual stimulants will not 

 hasten the unfolding of buds. 



88. Seed Germination. — The mature seed is also in a state of 

 rest. Its germination means the change to active life. Like in 

 buds, this rest may be light, or deep. Accordingly, many seeds 



