116 LUTHER BURBANK 



less experiments with other races of flowers, and 

 have every warrant for drawing such conclusions 

 as those just suggested. 



It may be added that there are yet other pos- 

 sibilities of stimulating variation by chemical 

 treatment of the developing ovaries of the flower 

 itself; or by subjecting the plant to unusual con- 

 ditions of temperature; but experiments of this 

 type, reference to which has been made in an 

 earlier chapter, have not often fallen within the 

 scope of my own work, and as yet have been 

 carried out only tentatively by others. They are 

 mentioned here only as suggesting that there are 

 other possibilities so various and so complicated 

 as to give full assurance that no single line of 

 investigation will ever reach a stage where it loses 

 interest because it has brought the investigator to 

 the end of the road. 



