156 BREEDING CROP PLANTS 



same result when heterozygous as when homozygous. C alone 

 or with A gives wrinkled petals and reduces the number of seeds 

 which set per capsule and induces lower viability of seeds. B 

 prevents the above action of C. B alone or in the presence of 

 A and C produces blue anthers and brown seeds. When B is 

 absent the seeds and anthers are yellow. Table XXXIV gives 

 the result of one of several similar studies. The tabular 

 presentation shows how carefully these studies were carried out. 



Inheritance of Size Characters. Studies of length of seed were 

 made with crosses of the wild angustifolium and cultivated 

 varieties (Tammes) as well as with crosses between cultivated 

 varieties. Seeds were of intermediate size in FI and segregation 

 occurred in F 2 . The number of individuals grown was not large 

 and the parental forms were not always again obtained. From 

 two to four multiple factors are necessary to explain results. 



Length and breadth of petal were also studied. Three forms 

 were used, a small-petalled white-flowered variety with a petal 

 breadth of 3.3 mm., the common varieties with a breadth of 

 7 mm. and an Egyptian cultivated blue-flowered variety with a 

 mean breadth of petal of 13.4 mm. In the cross between Egyp- 

 tian blue and common white the factors for color of flower 

 and seed and for size of seed were apparently inherited indepen- 

 dently. Breadth of petal ranged from one parent to the 

 other in F%. Several factors for size of flower were necessary 

 to explain results. The common blue with a petal breadth 

 of 7 mm. was crossed with the small-petalled white with an average 

 breadth of 3.3 mm. In F 2 all blue-flowered segregates agreed in 

 size with the blue parent and all white-flowered segregates had 

 small-sized petals. The cross between Egyptian blue and the 

 small-petalled white gave blue-flowered races with petals of inter- 

 mediate size in FI and segregation for flower color in F 2 . The 

 blue-flowered segregates gave a larger average breadth of petal 

 than the white segregates. Three hundred plants of each color 

 were examined. 



TABLE XXXV. CORRELATION BETWEEN COLOR OF COROLLA AND BREADTH 

 OF PETAL IN THE F GENERATIONS OF FLAX CROSSES 



RANGE, MM. AVERAGE, MM. 



300 blue-flowered plants 5.7-16.2 10.8 



300 white-flowered plants 2. 1-10.4 4.6 



Parent Egyptian blue 10.5-16.2 13.4 



Parent white-flowered . . 2.1-4.2 3.3 



