SOME EXPERIMENTS OF LUTFIER BURBANK. 203 



Not many of Mr. Burbank's results are due to unassisted selection, 

 as the processes of crossing and hybridization save time by the increase 

 of the rate or degree of variation. There is, however, no evident limit 

 to the results to be obtained by simple selection. New and permanent 

 species of wheat have, without a shadow of doubt, been produced by 

 selection alone. 



In the California poppy (Eschsclioltzia calif ornica), stripes of crim- 

 son are never seen on the inside. Mr. Burbank once found a seedling 

 in which the outside crimson had struck through like a crimson thread 

 which had been misplaced. In other generations, by selection, this red 

 was more and more increased, until finally out of it is developed a 

 crimson poppy, of which Mr. Burbank has now many specimens, seeding 

 more or less true to the type. The ' Shirley ' poppy (Papaver rliceas) 

 is well on the way to blue by selection. 



It is questioned whether competition in minor details, or ' intra- 

 specific selection/ can form species permanent as wild species are. As 

 to this, Mr. Burbank notes that the cultivated species produced after 

 the fashion of his crimson eschscholtzia ' have a very brief history com- 

 pared with the wild species, and, moreover, they are constantly being 

 placed in a new environment by man, being influenced by new soils, 

 new climates, new fertilizers and the like.' " Breeding to a fixed line 

 will bring fixed results. Man's desultory breeding is brief, the struggle 

 for existence is mostly absent, and new ideals and new uses are required 

 instead of ability to endure under natural conditions. Man's efforts 

 at selective breeding are fluctuating, with frequent saltations." 



Dr. De Vries notes that in the common sugar beet, which is a 

 biennial species, there are from one to ten per cent, of plants which bear 

 seed the first year. None of these is ever chosen for seed, and yet 

 the long-continued process of natural selection has never succeeded in 

 rooting them out. As to this Mr. Burbank observes : " This long-fixed 

 tendency to insure continued existence in the past is not yet bred out. 

 Analogous to this is the tendency in flocks to produce black sheep, and 

 the appearance of zebra stripes on horses — ancestral traits not yet bred 

 out." ' 



From the pale yellow Iceland poppy (Papaver nudicaule) are de- 

 veloped white, yellow and orange forms, and some with striped petals 

 and a strong tendency to become double. Selecting the Iceland poppy 

 for size alone, flowers three and one-half inches across have been de- 

 veloped. A large scarlet poppy, Papaver glaucum, closes its two inner 

 petals when a bee or two have entered, shutting in the bees, which buzz 

 angrily and cover themselves with pollen until they are set free. If 

 not visited by bees, the flowers do not close. 



A wild form of one of the Liliacas, Brodicea terrestris, was made 

 white by selection of the palest among the pale wild ones. Brodiaa 



