C1.AP. IV. COLOUR OF THE FLOWERS. 139 



The fifteen intercrossed plants actually produced 157 capsules ; 

 therefore twenty of them would have produced 209 '3 capsules, 

 and the seeds would have weighed 208 '48 grains. 



The ten self-fertilised plants actually produced 70 capsules ; 

 therefore twenty of them would have produced 140 capsules ; 

 and the seeds would have weighed 153 '2 grains. 



From these data we get the following ratios : 



Number of capsules produced by an equal number of plants of 

 the three lots. 



Number of Capsules. 



The London-crossed to the self-fertilised, as 100 to 39 

 The London-crossed to the intercrossed, as 100 to 45 

 The Intercrossed to the self-fertilised as 100 to 67 



Weight of seeds produced by an equal number of plants of th 

 three lots. 



Weight of Seed. 



The London-crossed to the self- fertilised, as 100 to 33 

 The London-crossed to the intercrossed, as 100 to 45 

 The Intercrossed to the self-fertilised, as 100 to 73 



We thus see how greatly the offspring from the self-fertilised 

 plants of the third generation crossed by a fresh stock, had 

 their fertility increased, whether tested by the number of cap- 

 sules produced or by the weight of the contained seeds; this 

 latter being the more trustworthy method. Even the offspring 

 from the self-fertilised plants crossed by one of the crossed 

 plants of the same stock, notwithstanding that both lots had 

 been long subjected to the same conditions, had their fertility 

 considerably increased, as tested by the same two methods. 



In conclusion it may be well to repeat in reference to the 

 fertility of these three lots of plants, that their flowers were 

 left freely exposed to the visits of insects and were undoubtedly 

 crossed by them, as may be inferred from the large number of good 

 capsules produced. These plants were all the offspring of the 

 same mother-plants, and the strongly marked difference in their 

 fertility must be attributed to the nature of the pollen employed 

 in fertilising their parents ; and the difference in the nature of the 

 pollen must be attributed to the different treatment to which 

 the pollen-bearing parents had been subjected during several 

 previous generations. 



Colour of the Flowers. The flowers produced by the self-fertilised 



