S. C. Harland 203 



On the chromosome hypothesis of Morgan et al. (1915), the factors 

 B, P, and E, are located in the same chromosome. The evidence is not 

 strong enough to say that complete repulsion occurs between B and E, 

 and between B and P ; the factors are, however, so near together that 

 crossing over seldom occurs. 



If these three factors could be shown to occupy identical loci, they 

 would then constitute a triple series of multiple allelomorphs. In 

 nearly all cases in which multiple allelomorphs have been discovered} 

 the factor-differences produce similar effects. The fact that B, P, and 

 E, all produce colouration of young pod, calyx, and peduncle as one of 

 their effects is an argument in favour of the multiple allelomorph 

 theory. 



4. Flower Colour. 



In the F2 of a cross between red (dark flower), and Para (white 

 flower), it was expected that segregation would occur into 3 dark and 1 

 white. Some of the apparently white flowers were found on close 

 examination to possess a minute degree of anthocyanin pigmentation in 

 the wings. This cannot usually be seen with the naked eye, and is best 

 detected by dipping the flower in dilute hydrochloric acid, when a pink 

 flush appears if pigmentation be present. This type of flower colour 

 may conveniently be termed "tinged." The proportions in which dark, 

 tinged, and white, occurred in the cross red by Para were : 



Plants Dark Tinged White 



18 14 3 1 



The F3 results were as follows : 



1. 3 darks segregated into dark, tinged, and white. 



Plants Dark Tinged White 



118 95 19 4 



46 35 ,10 1 



46 34 10 2 



Totals 210 164 39 7 



Expectation on 12 : 3 : 1 basis — 157 39 13 



2. 7 darks segregated into dark and tinged in the 3 : 1 ratio. 



Plants Dark Tinged 



94 73 21 



Expected ... 71 23 



3. 3 darks bred true (76 plants). 



4. 2 tinged segregated into tinged and white in the 3 : 1 ratio. 



Plants Tinged White 



116 90 26 



Expected ... 87 29 



5. 1 tinged bred true (16 plants). 



