No. 573] CHROMOSOME HYPOTHESIS OF LIN K AGE 529 



There is one other gene which probably belongs in the 

 first chromosome, namely, the intensifier found in the 

 " black knight" race. The linkage data of red color and 

 intensity of color have been given in Report II to the 

 Evolution Committee, page 90. 



TABLE II 

 Bed Color and Intense Color 



Coupling ... 149 29 35 22 .527 1.9:1 35. 



If these data are significant, then intense is in the first 

 chromosome at a locus about 35 to the right or left of red. 

 It should give about 24 (35 - 11) or 46 (35 + 11) per cent, 

 of crossing over with round, depending on whether it lies 

 about 24 to the left of round or 35 to the right of red. 



The Second Chromosome of Sweet Peas 

 In the case of the second chromosome in sweet peas, 

 the linkage values are based on smaller numbers, but the 

 order of genes is more certain. 



The first linkage case of this chromosome was that of 

 sterile anthers and light axils. Later the cretin form of 

 flower was found to belong to this linkage group. As in 

 the case of the first chromosome, I have summarized the 

 tables of Punnett in Table III. 



TABLE III 

 Chromosome II 

 terile Anthers and Light Axil 



Light Axils and Cretin Flower 



