LUTHER BURBANK 



few in number, and small as they are, we are 

 forced to conclude that each of them must be the 

 carrier not of a single potential trait or tendency 

 but of a multitude of such potential traits or 

 tendencies. 



Our practical experiments in plant breeding 

 have shown us that we deal often with a dozen or 

 more tangible characters that are grouped against 

 each other in opposing pairs definitive qualities 

 of size or color or flavor of fruit and all the rest 

 and it requires but a moment's thought to see that 

 each of these "unit characters" is in reality made 

 up of a multitude of minor characters. 



Heredity carries all of these definitely from one 

 generation to another; so their potentialities must 

 be represented within the structure of the 

 chromosomes; and there are by no means 

 chromosomes enough to supply one for each 

 hereditary character. 



So we are obliged to assume that each 

 chromosome is in itself a complex structure, and 

 that within that structure there are subordinate 

 structures like the individual bricks and boards 

 and nails and rivets that go to make the structure 

 of any piece of human architecture that deter- 

 mine by their quality or their arrangement the 

 specific potentialities of the future organism. 

 Each chromosome, in other words, must be thought 



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