316 Plant Physiology 



existed as leaves in minute form in the winter bud. Re- 

 cent studies by Miss Moore indicate that a considerable 

 number of our north temperate deciduous trees are of this 

 type ; and a number of observations suggest that it is the 

 method common among conifers. Excellent examples of 

 this type are offered by the beech and pine. In the beech 

 the first sign of activity in the spring is that of gradual swell- 

 ing of the bud, and at first a rather general stretching of 

 the internodes. The bud quickly doubles its former length, 

 and by this time observations upon the method of elonga- 

 tion are most easily made. It will be found that the 

 growth increments in the basal internodes are at first 

 stronger, successively passing to others, and the terminal 

 internodes are the last to show rapid extension. Never- 

 theless, there is a distinct grand period of growth for each 

 internode in turn. 



In the pine, on the other hand, there is this difference : 

 the shoot is unsegmented, and every portion of the bud 

 axis from base to apex becomes successively the region 

 of greatest extension; although in this case extension is 

 more nearly uniform throughout the whole shoot axis. 

 It appears that pomaceous fruits ordinarily follow the 

 plan of this general type, but peaches may frequently fall 

 into the next class. 



(2) From the data available it would seem that the 

 lilac, willow, and some other trees may develop normally 

 during the summer a few more leaves than are ordinarily 

 contained in the resting bud. In this case there is, of 

 course, a formation of new nodes and internodes from the 

 young meristem as the bud is expanded, or at least dur- 

 ing the grand period of growth of the shoot. 



