ADAPTATION 127 



CHAPTER XI 



ADAPTATION 



THE 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 



