6 Chapters in Modern Botany CHAP. 



answers alone successively satisfied many minds, Darwin 

 himself at least inclined towards some varying compromise 

 of them. And as the student learns the really scientific atti- 

 tude, that of not learning answers but of asking questions, 

 new puzzles arise. Thus, what influence are we to place 

 upon the geographical isolation through many generations 

 of the incipient Darlingtonia from its kindred Sarracenias? 

 How far does it modify our natural selectionist position 

 with its characteristic insistance upon adaptation to external 

 uses when we note that the odd hood of the Darlingtonia 

 is developed merely by increasing the relative rate of growth 

 of the outer and upper surface of the Sarracenia pitcher, 

 especially as we approach its mid-rib, so producing not 

 only the inflation but the curvature, and even the stretch- 

 ing apart of the leaf-tissue so as to leave the pretty 

 window-like patches? But if this be clear we have already 

 got a step below the conventional Darwinian level of 

 external adaptation, below the idea of progress merely 

 through the cumulative patenting of mechanical improve- 

 ments in our fly-traps. Helpful though that explanation is, 

 so far as it goes, we have in fact reached a new and deeper 

 plane of thought on which it may become necessary to 

 work out an entirely new set of evolutionary interpretations. 

 The outer world of external and mechanical adaptations 

 once left behind, we are at once brought face to face with 

 the internal and vital processes, and have to grapple with 

 the problems of organic growth, both general and special; 

 in other words, it is in terms of the laws of growth that we 

 have to reinterpret the phenomena of development. We are 

 familiar with these differences of growth of different regions 

 of the leaf, as in young leaves of ferns, but the experimental 

 study in detail lies still before us. Deliberately to arrange 

 new conditions for our Sarracenia so that it shall at least 

 begin to roll its leaf into the form of Darlingtonia is, how- 



