78 ALPINE AND ARCTIC PLANTS [CHAP. vm. 



above - described varietal, sub-specific, or even 

 it may be specific characters, are simply the 

 result of the direct action of the environment 

 upon the plants themselves ; which by per- 

 petuation become relatively fixed, stable and 

 hereditary." 



I have treated this subject so fully, with a 

 great number of examples, that I would refer 

 the reader to the book already mentioned for 

 further details. 



I will here pause to repeat that my object in 

 giving all the preceding details is not to propose 

 any theory whatever, but to show on wh&tfaett 

 the two conclusions are based, viz. : (1) that all 

 structures arise by direct adaptation by response ; 

 and (2) that they may or may not be hereditary. 

 The condition for the latter is solely a question 

 of time in the number of generations which have 

 been subjected to the same conditions of life 

 (see p. 22). 



