PLANT BREEDING 39 



which now inhabit the earth has been secured 

 to them only by their power of adaptation to 

 crossings, for, through the variations produced 

 by the combination of numerous tendencies, 

 individuals are produced which are better en- 

 dowed to meet the prevailing conditions of life. 

 Thus to nature's persistence in crossing do we 

 owe all that earth now produces in man, animals, 

 or plants; and this magnificently stupendous 

 fact may also be safely carried into the domain 

 of chemistry as well, for what is common air and 

 water but nature's earlier efforts in that line, 

 and our nourishing foods but the result of 

 myriad complex chemical affinities of later date? 

 Natural and artificial crossing and hybridiza 

 tion are without doubt among the principal 

 remote causes of nearly all otherwise perplexing 

 or unaccountable sports and strange modifica- 

 tions, and also of many of the now well-estab- 

 lished species. Variations, without immediate 

 antecedent crossing, occur always and every- 

 where from a combination of past crossings and 

 environments, for potential adaptations often 

 exist through generations without becoming 

 actual, and when we fully grasp these facts there 

 is nothing so very mysterious in the sudden 

 appearance of sports ; but still further intelligent 

 crossing produces more immediate results and of 



