1911.] Coupling and Repulsion in Primula sinensis. 15 



the partial suppression of colour in the stem, and gives rise to the dominant 

 light stems (pallifying factor), and (2) the factor, previously mentioned, 

 which completely suppresses colour in the stigma. 



The repulsion hetween these two factors was observed in the progeny of a 

 cross in which a plant having red stems and red stigma was mated with a 

 plant which was almost devoid of colour in the stem and had the dominant 

 green stigma. The F 2 from this cross contained a long series of forms, and 

 included plants having stems much darker in colour than those of the red- 

 stemmed parent. The green-stemmed parent was therefore without the palli- 

 fying factor. Certain individuals of the F2 were tested by self-fertilisation, 

 and three of them, all having light red stems and green stigmas, gave F 3 

 families in which the complete repulsion between the pallifying factor and 

 the factor for green stigma was shown, in the fact that none of the offspring 

 with dark stems had red stigmas. The numbers obtained in the three 

 families are shown below. 





Light stem, 



Light stem, 



Dark stem, 



Dark stem, 







green stigma. 



red stigma. 



green stigma. 



red stigma. 



Total. 





11 



8 



5 







24 





95 



40 



45 







180 





31 



18 



12 







61 



Total 



.. 137 



66 



62 







265 



Expectation 



.. 132-5 



66 -25 



66 -25 







265 



I am greatly indebted to the authorities of the John Innes Horticultural 

 Institution for allowing a large number of plants to be grown there. The 

 assistance thus extended to me has enabled me largely to increase the scope 

 of my experiments upon Primula sinensis. 



