264 



KARL B. KRISTOFFERSON 



a combination occurred resulting in a spreading out of the honey-guide 

 on the whole of the spur-petal. 



Table 7 shows the length of the honey-guide in the parent-lines, 

 Fa and F.- Unfortunately I could only make measurements on one 

 single Fj -plant; the others had died out. 5 flowers were measured 

 on each individual of the parents and of Fo. The last developed 

 flower was measured on each of the large branches. These were 5, 

 as a rule. 



TABLE 8. The variation of the index of the length of the spur-petal: 



the length of the honey-guide in the parents and the Fi- 



and F.-generations. 



Table 8 shows the index of the length of the spur-petal to the 

 length of the honey-guide. The length of the spur-petal and the 

 honey-guide were measured at the same time, of course; probably 

 it would have been more correct to measure the area of the spur- 

 petal and the honey-guide, but these measurements are too tedious. 



The number of the individuals with a dark-yellow coloured spur- 

 petal throughout is 8. Their index is evidently =1. In table 7 they 

 correspond to the individuals in the classes 5 — 7,5. 



If the number of the plants with quite dark-yellow spur-petals 

 are counted, the values of 8 dark-yellow and 138 light-yellow^ are 

 obtained. The ratio pro 16 is 0,877:15,123. The observed ratio lies 

 within the limits of the ratio for a dihybrid segregation. 



This ratio indicates a dihybrid segregation. The appearance of 

 the dark-yellow spur-petals in F, may be explained by the assump- 

 tion of one factor in V. tricolor and another in V. arvensis, which 

 both have an inhibiting effect on the development of the honey- 



