LUTHER BURBANK 



increase of the flower, although productivity was 

 also emphasized. 



Indeed, it is to the fact of such stimulus of 

 growth by hybridization that my success in devel- 

 oping the gigantic races of spineless cactus is due. 

 Hybridizing Materials and Methods 



The hand poUenizing of the cactus, which was 

 the foundation of these experiments in the pro- 

 ducing of the new spineless races, presents no 

 technical difficulties yet requires to be carried out 

 in a particular way. 



The cactus flowers open only in the very hottest 

 part of the day, and within fifteen minutes after 

 the pollen-bearers are exposed there is probability 

 that the wind or bees will have accomplished self- 

 fertilization of many of the flowers. It is neces- 

 sary, therefore, for the experimenter to be on the 

 spot, to anticipate the opening of the flower. 



Our method was to collect pollen in watch crys- 

 tals, and, if necessary, keep it until the flowers we 

 wished to pollenize were matured. As the differ- 

 ent varieties of cactus bloom at different seasons, 

 it was sometimes necessary to keep the pollen for 

 a considerable period. 



When the plant to be poUenized is ready to 

 bloom, nothing more is necessary than to remove 

 its stamens just before they are matured, and to . 

 dust pollen from watch crystal witli a camel's hair 



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