204 Double Stocks [ch. xi 



symmetrical or probable scheme of character-distribution by 

 which such a phenomenon can be represented '^. 



The various difficulties of the case culminate in the 

 fact which seems well established, that though the double- 

 throwers generally give 7 singles : 9 doubles — with certain 

 departures from this ratio which are probably not fortuitous — 

 yet F^ raised from single x double-thrower, and from the 

 reciprocal cross, always on self-fertilisation gives 3 singles : 

 I doublet. 



* For further information on this subject see the Appendix to Part I. 



t The relation of white to cream-colour in the strain known as "Sulphur" 

 is approximately the same as that of single to double described above. 

 "Sulphurs" are single whites throwing singles all white, and doubles which 

 are usually arams with whites as exceptions. The pollen-grains of "Sulphur" 

 all bear cream, while of the ovules some are creams and some whites. 



