Application of Biological Principles to Plant Breeding 125 



produced having the greater number of leaves of the Suma- 

 tra parent and the stocky habit of growth and large leaves 

 of the Havana parent (Fig. 53). The first interpretation 

 of this result was that an entirely new variation had appeared 

 for the Sumatra does not 

 usually have as many as 

 26 leaves. The writer has 

 been able to show, how- 

 ever, that the actual strain 

 of Sumatra used as the 

 parent had an average of 

 26 leaves, and data have 

 now been collected which 

 indicate that the new 

 variety is a simple recom- 

 bination of the characters 

 possessed by the two par- 

 ents giving a strain averag- 

 ing 30-50 per cent greater 

 yield than the old Havana 

 variety (Fig. 54). 



In a similar way Orton 

 has combined the edible 

 quality of the watermelon 

 with the resistance to wilt of 

 the citron or stock melon; 

 Webber has combined the 

 fine, long, strong lint of the sea-island cotton with the large 

 bolls and productiveness of the upland cotton; Price has 

 made many new combinations in. tomatoes; and von 

 Riimker has produced numerous valuable varieties of rye 

 and barley. So the list might run on and on. Hundreds 



FIG. 53. Nicotiana tabacum variety 

 " Sumatra." A tall habit of growth with 

 about 26 small leaves. 



