July, 1909.] 



Miscellaneous 



earliest sports from this were the pure 

 white form and the variety known as 

 painted lady— with a red standard and 

 white wings. Subsequently an enormous 

 number of other colours have been 

 produced. In one of his experiments 

 Professor Bateson crossed together 

 two sweet peas with perfectly white 

 flowers, and from the cross he raised 

 plants with purple flowers— not a con- 

 juring trick but a case of reversion. 



The next step was to sow the self- 

 fertilised seed of the aoloured cross-bred 

 plants to produce a second generation. 

 In this generation a very large number 

 of plants was raised, some with white 

 and some with coloured flowers, and it 

 was found that the proportion of 

 coloured to white-flowered plants was 

 9: 7. The explanation is given in the 

 diagram below which shows the com- 

 position of the second generation. The 



AB Ab a B a b 



Ah 



aB 



ab 



Fig. 2. 



secret is as follow?. The appearance of 

 any colour depends upon the simul- 

 taneous presence of two factors A and B. 

 If either of these factors is absent from 

 a plant its flowers appear white. Thus 

 Ab and aB are both white. The two 

 original parents are supposed to have 

 beeu of this nature, from one of the 

 two necessary factors for colour was 

 wanting, and from the other the 

 second factor was wanting. But when 

 these two were crossed together, the 

 7 



cross bred ABab contained both factors, 

 and the purple colour at once became 

 visible. The further history of the 

 case may readily be traced from the 

 diagram, refering if necessary to the 

 description of the inheritance of two 

 pairs of characters already given at the 

 beginning of the present article. We 

 must suppose that originally white forms 

 arose from the coloured by two distinct 

 processes of sporting. In one of these 

 the A factor was lost and in the other the 



