46 THE SURVIVAL OF THE UNLIKE. [l 



season's growth. When English plants are grown in 

 America, they usually grow until killed by fall frosts; 

 but after a few generations of plants, they acquire the 

 quick and decisive habit of ripening which is so charac- 

 teristic of our vegetation. I once made an extended test 

 of onions from English and American seeds (Bull. 31, 

 Mich. Agric. College), and was astonished to find that 

 nearly all of the English varieties continued to grow 

 until frost and failed to "bottom," whilst our domestic 

 varieties ripened up in advance of freezing weather. 

 This was true even of the Yellow Danvers and Red 

 Wethersfield, varieties of American origin and which 

 could not have been grown very many years in Eng- 

 land. Every horticulturist of much experience must 

 have noticed similar unmistakable influences of climate 

 upon the duration of plants. 



A most interesting type of examples of quick influ- 

 ence of climate upon plants — not only upon their dura- 

 tion but upon habit and structural characters — is that 

 associated with the growing of "stock seed" by seeds- 

 men. Because of uncertainties of weather in the eastern 

 states, it is now the practice to grow seeds of onion, lima 

 bean and other plants in California or other warm 

 regions; but the plants so readily acquire the habit of 

 long -continuing growth as to be thereafter grown with 

 difficulty in the northeastern states. It is, therefore, 

 necessary that the seedsman shall raise his stock seed 

 each year in his own geographical region, and this seed 

 is each year sent to California for the growing of the 

 commercial seed crop. In other words, the seed of Cali- 

 fornia-grown onions is sold only for the purpose of 

 growing onion bulbs for market, and is not ])l!nited for 

 the raising of a successive crop of seed. This results in 



