Kleinere Mitteilungen, 

 table II 



179 



at the very least two factors at work. I regret that owing to an inaccu- 

 racy I am not in a position to say with certainty how these correlations 

 manifested themselves at different heights of the tree (in the same way as 

 I did with an analysis of the curves in the former treatises). It may easily be 

 that e. g. the lower half of the tree has a positive correlation and the 

 upper half a negative, or the other way about. The differently directed 

 correlations may be again any expression of "modification" during 

 the development of the tree, just as I have explained in the third 

 communication^ From the point of view of the theory put forward at 

 that time (S 2, the third communication) in analogy with other physiological 

 facts we should arrive at the conclusion that stimulation by the factor 

 through external circumstances may be such, that the plant (in casu de cor- 

 relatione) may react negatively instead of ])ositively (or the reverse). This 

 is more plausible than the supposition that one factor has a positive cor- 

 relation and the other factor a negative, which would make the matter 



') Vol. U of this periodical. 



