ADAPTATION 127 
CHAPTER XI 
ADAPTATION 
Tue sketch of the formation and distribu- 
tion of mechanical tissues attempted in the 
last few chapters, raises rather forcibly the 
question of how the existence and elaboration 
of the green leaf has succeeded in so pro- 
foundly affecting, even in this one particular, 
the construction of the whole organism. Of 
course, we recognise that the influence of the 
leaf depends on its position as the chief bearer 
of the chlorophyll of the plant, and to this 
extent our question becomes more precise. 
But if we limit ourselves for the moment to 
the consideration of this single problem of 
mechanical adaptation and correlation, in 
order to try to get a clear issue, we find that 
the issue is far from being clear, and the 
approaches to the problem itself bristle with 
difficulties. 
It is true that we can readily find, in our 
analysis of the influence of the leaf, a very 
complete justification for the various me- 
chanical adaptations and correlations which 
we have learnt to recognise. It is but one 
aspect of the much larger generalisation that 
there is a real and obvious relation between 
