THE BA.TTLE OF LIFE. 115 



flowering period, and bring about an increased production 

 of seed. But any change that may be induced is of a 

 physiological kind, affecting the development of the indi- 

 vidual, not the character of the species. By no combina- 

 tion of manurial elements is it possible to bring about 

 that kind of change which a naturalist would consider 

 specific. 



iS 



