CHAP. IV. IBEEIS UMBELLATA. 103 



of an inch. We thus see that reversion to a more natural con- 

 dition acted more powerfully in favouring the ultimate growth 

 of these plants than did a cross ; but it should be remembered 

 that the cross was with a semi-sterile variety having a feeble 

 constitution. 



IBEEIS UMBELLATA. 

 For. Eermesiana. 



This variety produced plenty of spontaneously self-fertilised 

 seed under a net. Other plants in pots in the greenhouse were 

 left uncovered, and as I saw small flies visiting the flowers, it 

 seemed probable that they would be intercrossed. Consequently 

 seeds supposed to have been thus crossed and spontaneously self- 

 fertilised seeds were sown on opposite sides of a pot. The 

 self-fertilised seedlings grew from the first quicker than the 

 supposed crossed seedlings, and when both lots were in full 

 flower the former were from 5 to 6 inches higher than the crossed ! 

 I record in my notes that the self-fertilised seeds from which 

 these self-fertilised plants were raised were not so well ripened 

 as the crossed ; and this may possibly have caused, from pre- 

 mature growth, the great difference in their height, in nearly 

 the same manner as when self-fertilised seeds of other plants 

 were sown a few days before the crossed in the same pot. 

 We have seen a somewhat analogous case with the self-fertilised 

 plants of the eighth generation of Ipomcea, raised from unhealthy 

 parents. It is a curious circumstance, that two other lots of the 

 above seeds were sown in pure sand mixed with burnt earth, 

 and therefore without any organic matter ; and here the sup- 

 posed crossed seedlings grew to double the height of the self- 

 fertilised, before both lots died, as necessarily occurred at an 

 early period. We shall hereafter meet with another case 

 apparently analogous to this of Iberis in the third generation 

 of Petunia. 



The above self*fertilised plants were allowed to fertilise them- 

 selves again under a net, yielding self-fertilised plants of the 

 second generation, and the supposed crossed plants were crossed 

 by pollen of a distinct plant ; but from want of time this was done 

 in a careless manner, namely, by smearing one head of expanded 

 flowers over another. I should have thought that this would 

 have succeeded, and perhaps it did so; but the fact of 108 

 of the self-fertilised seeds weighing 4 '87 grains, whilst the same 

 number of the supposed crossed seeds weighed only 3 "57 grains, 



