LUTHER BURBANK 



six generations. Much depends on whether the 

 qualities under observation act as " dominant " or 

 as " recessive" qualities in the Mendelian sense. 

 The exact meaning of this and the manner of test- 

 ing have already been explained, and will be 

 further elaborated in another connection. 



The prime essential, however, is that the plants 

 shall be rigidly guarded against cross-fertiliza- 

 tion. New varieties are created by cross-polleniz- 

 ing ; they are fixed by self-pollenizing. In a care- 

 fully conducted experiment, it will be well to cover 

 the plant with a net, to keep the bees from inter- 

 fering, meantime hand-pollenizing each blossom 

 with pollen from other flowers of the same plant. 



METHODS OF POLLENIZING 



In order to carry out this all-important business 

 of pollenizing (cross-breeding in some cases, in- 

 breeding in others), it will obviously be necessary 

 to study the anatomical structure of different 

 flowers. The principle is always the same pollen 

 from one flower is to be carried to the pistil of 

 another. But some flowers have the stamens ar- 

 ranged in a peculiar way, and the casual inspector 

 may not at first glance recognize them. 



Plants of the iris tribe, for example, have a 

 peculiar mechanism whereby the pollen is de- 

 posited on the back of a bee, and then is scraped 

 off by the pistil of the next flower that the bee 

 visits. The amateur botanist might not at first 

 glance recognize the pistil, and hence might be 



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