512 MacDougal : Some Correlations of Leaves 



such manner as vastly to increase their capacity for photosynthe- 

 sis and transpiration. 



VI. The loss of the lamina acts as a stimulus which induces a 

 development and differentiation of spongy parenchymatous and 

 other tissues in the stipule, and the formation of chlorophyl. 



VII. The lateral buds of Acer on internodes formed during the 

 previous season were awakened by defoliation of the extending 

 apical portion. 



VIII. The period of activity of the vegetative point of the 

 terminal portion of a woody branch is not lengthened as a result 

 of defoliation. 



IX. The total length of the newly formed portion of the 

 branches defoliated during growth was thirty to sixty per cent, 

 less than that of normal branches occupying the same relative 

 positions on the shoot. 



X. The number of internodes developed on defoliated branches 

 was greater than in the normal. 



XI. The defoliated internodes were of a diameter not greater, 

 sometimes less than the normal, and had accomplished less perfect 

 differentiation. 



XII. Branches compelled to accomplish growth in a defoliated 

 condition generally are found to be in a state of hypoplasia, the 

 undeveloped and imperfectly differentiated condition of the tissues 

 being due to the lack of correlative stimuli. 



New York Botanical Garden. 



