434 



ZONES AND REGIONS [Pt. Ill, Sect. II 



the growth in March will still be more energetic than that in February 

 and proceed with increasing rapidity. If however we compare several 

 years with one another, the influence of temperature appears very plainly, 

 as the curve in a warm spring is steeper and leads to an earlier flowering 

 than in a cold spring. At the same time Askenasy has not taken into 

 account very low temperatures, which are not uncommon in March; it 

 remains for botanists to investigate the course of the grand period, in 

 the case of slight frosts in spring — severe frost is known to kill the 

 growing buds. 



The dominating influence of inherent characters over the effects of 

 temperature is still more remarkable than the features exhibited by the 

 grand period ; this is revealed in the fact that a rise of temperature in 

 October does not awaken the resting buds into activity, whereas it does 

 so from the end of November onwards, and is the more effective the 

 nearer the commencement of the rise is to the end of the normal resting 

 period. The phenomenon cannot be due to growth having taken place 

 in the interval, for the increased weight of the buds from the beginning 

 of October to the end of November is hardly appreciable, and the stalks 

 of the buds apparently remain at the same stage of development. 



In illustration of the above we may give the following short tabular 

 statement regarding the sprouting of branches of the gean-tree ; there are 

 no early dates in the table, as the experiment was first begun in December. 



SPROUTING OF BRANCHES OF THE GEAN-TREE UNDER A RISE 

 OF TEMPERATURE. (After Askenasy.) 



To the external periodicity revealed in the phenomena of growth there 

 is a corresponding internal periodicity in the processes of metabolism 1 . 

 From the moment when the leaves are fully grown until their fall, a 

 continual stream of assimilated matter flows from the green cells into 

 the branches and stem. Products of assimilation free from nitrogen, 

 which we alone consider, because those containing nitrogen are too little 

 known, travel in the form of easily diffusible glucose ; on the way, this 



1 Alf. Fischer, op. cit. 



