go Carbon Assifnitaiion. 



Table XVI. 



Assimilation Numbers of Leaves from the same Plant, 



but ill different Stages of Development. 



25° 5% CO3 48000 iux. 



It will be observed from this table that the chlorophyll content 

 increases with the age of the leaves ; so does the assimilatory power, 

 but n ot in the same degree. Consequently the assimilation numbei^ 

 decreases. 



Further data in regard to the variation of the assimilation 

 number with the state of development of the leaves are given in the 

 following table. 



Table XVII shows clearly that after a time, although the 

 c hlorophy ll content increases, yet the assimilation number 

 d jmini shes. From this fact Willstatter concludes that the chloro- 

 phyll is present in excess, while some other internal factor (enzyme) 

 is limiting the rate of assimilation. -"'''' 



Autumn Leaves. 



In autumn leaves the conditions are very complex. The general 

 rule is that with decreasing chlorophyll content the assimilation 

 decreases as is shown in Table XVIII. Leaves rich or poor in 

 chlorophyll give the same assimilation number. 



