May, 1920.] YASUI :— GENETIC AL STUDIES. Q\ 



latter, the anthocyanin formation being the result of the action of 

 the reducer upon a flavone derivation (Shibata 1915, Wiulstatter 

 and Everest 1913, &c.) 



This assumption is supported by the fact that the white petal 

 does not contain flavone derivations, as was proved by the chemical 

 test that the extract of the petal of the white flower never produces 

 red anthocyanin pigment by the usual reducing method for the flavone 

 derivation, nor does the white petal react to ammonia vapour ; so 

 we may conclude that the id C derived from the yellow parent in 

 cooperation with the id R from the white parent produced the 

 magenta Fi flower. 



In the plant kingdom, there are a few cases known, that the 

 yellow mated with the white produced the magenta Fi plant, as are 

 reported by Correns (1903) on Mirabilis Jalapa, by W'heldale 

 (1907) and by Baur (1908) on Antirrhinum, by Marryat (1909) on 

 Mirabilis, by Shull (1907) on the seed coat of Phaseolus, by Leake 

 (1911) on Cotton plant. 



The distinction of the two classes of magentas as well as of 

 yellows in F2 plants in this experiment may be ascribed to the 

 differences of the number of the ids concerned, but I retain the explana- 

 tion until later. 



C. Back-Cross Experiments Relating both the Colours of the Petals 

 and the Singleness or Doubleness of the Flowers 



Experiment 1. White single ccRRdd x Magenta double CcRrDd. 

 The results of the experiment is shown in the table 6. 



Table 6. 



Magenta Magenta "White White 



double single double single Total 



Pedigree No. 18 15 15 15 13 58 



131 4 2 2 3 11 



123 7 6 2 5 20 



Act. observ 26 23 19 21 89 



Theor. expect, as 1:1:1:1. 22.25 22.25 22.25 22.25 89 



Deviation +3.75 +0.75 —3.25 —1.25 



fl^abs ±4.08 ±4.08 ±4.08 ±4.08 



Deviat'/^abs <1 <1 <1 <1 



Another back-cross, pale yellow x magenta double, was made 



too, and the result was found in the ratio 10 magenta : 11 yellow. 



The interpretation of the ratio 1 : 1 : 1 : 1 in the table 6 is this : 





