THE LAWS OF HEREDITY 



in such a case, that the offspring cannot be like 

 both parents in color. 



Here, then, is a complication that introduces 

 an element of uncertainty into the otherwise sim- 

 ple law of heredity. 



It is perhaps not too much to say that all ques- 

 tions of heredity center chiefly around the in- 

 quiry as to just what are the mutual relations of 

 more or less antagonistic qualities when com- 

 mingled through cross-fertilization. 



HYBRIDIZATION AND VARIATION 



At an early stage of his work in plant develop- 

 ment, Mr. Burbank discovered that it is possi- 

 ble to hybridize species that are seemingly quite 

 divergent, and that the results are often very 

 striking. He brought together plants from differ- 

 ent continents, and found that in many cases they 

 would interbreed. 



For example, he hybridized the Siberian rasp- 

 berry with the California dewberry, producing a 

 remarkable new fruit which he called the Primus 

 berry. 



Everyone is familiar with the conspicuous 

 differences between a raspberry and a blackberry. 

 To mention only one of them, the raspberry leaves 

 its receptacle on the vine when picked, while the 

 blackberry retains the receptacle as part of the 

 fruit. It at once becomes an interesting question 

 as to how these divergent qualities are harmon- 

 ized in hybridized offspring. 



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