Cultivated Elementary Species 81 



flax remain closed until the seeds are liberated 

 by threshing. It seems probable that the first 

 form or Linum crepitans might thrive in the 

 wild state as well as any other plant, while in 

 the common species those qualities are lacking 

 which are required for a normal dissemination 

 of the seeds. White or blue flowers, high or 

 dwarf stems, more or less branching at the base 

 and sundry other qualities distinguish the va- 

 rieties, aside from the special industrial differ- 

 ence of the fibres. Even the life-history varies 

 from annual and biennial, to perennial. 



It would take us too long to consider other in- 

 stances. It is well known that corn, though 

 considered as a single botanical species, is rep- 

 resented by different subspecies and varieties 

 in nearly every region in which it is grown. Of 

 course its history is unknown and it is impossi- 

 ble to decide whether all the tall and dwarf 

 forms, or starchy and sweet varieties, dented 

 or rounded kernels, and hundreds of others are 

 older than culture or have come into existence 

 during historic times, or as some assume, 

 through the agency of man. But our main 

 point now is not the origin, but only the 

 existence of constant and sharply differentiated 

 forms within botanical species. Nearly every 

 cultivated plant affords instances of such di- 

 versity. Some include a few types only, while 



