Decline of Growth and the Rest Period. 115 



not adapted by nature. We may, however, through the 

 variations of offspring (18), secure varieties in some 

 cases that can endure an environment which the parents 

 could not endure. 



176. Plant Processes during the Rest Period may 

 not entirely cease. Although food preparation is wholly 

 suspended, root growth and the callusing (72) of in- 

 jured root surfaces proceed to some extent during win- 

 ter in unfrozen layers of soil; and in sufficiently mild 

 weather, the reserve food in the stem gradually moves 

 in the direction of the terminal buds. 



177. Cuttings (358) of Woody Plants are Prefer 

 ably Made in Autumn in climates of severe winters 

 and buried in the ground below the limit of hard freez- 

 ing, in order that callusing (72) and the transfer of 

 food may make some progress before the final planting. 



178. The "Turn of the Year." Toward the close of 

 the dormant season, vegetation, as if benefited by the 

 rest, is prepared to start with renewed vigor, even at 

 moderate temperatures. Buds, that remained dormant 

 during the latter part of the previous summer, push 

 into growth with the first warm days of spring, and 

 many seeds, that could not be induced to germinate the 

 preceding autumn, start with vigor as soon as the soil 

 is sufficiently warm. 



The cause for this energetic resumption of plant 

 growth after the rest period is not well understood, 

 but exposure to cold, in the case of temperate plants, 

 and to prolonged dryness in that of tropical ones, 

 doubtless explains it in part, for it is well known that 

 potato tubers may be induced to start their buds soon 



