304 TRANSMITTED EFFECTS OF A CROSS. CHAP. VIII 



open ground and near to other plants of heartsease, 

 and as both produced an abundance of very fine cap- 

 sules, the flowers on both were certainly cross-fertilised 

 by insects. Seeds were collected from both plants, and 

 seedlings raised from them. Those from the crossed 

 plants flowered in all three pots before those from the 

 self-fertilised plants ; and when fully grown the former 

 were to the latter in height as 100 to 82. As both sets 

 of plants were the product of cross-fertilisation, the 

 difference in their growth and period of flowering was 

 clearly due to their parents having been of crossed and 

 self-fertilised parentage ; and it is equally clear that 

 they transmitted different constitutional powers to their 

 offspring, the grandchildren of the plants which were 

 originally crossed and self-fertilised. 



Thirdly, the Sweet Pea (Laihyrus odoratus) habi- 

 tually fertilises itself in this country. As I possessed 

 plants, the parents and grandparents of which had 

 been artificially crossed and other plants descended 

 from the same parents which had been self-fertilised 

 for many previous generations, these two lots of plants 

 were allowed to fertilise themselves under a net, and 

 their self-fertilised seeds saved. The seedlings thus 

 raised were grown in competition with each other in the 

 usual manner, and differed in their powers of growth. 

 Those from the self-fertilised plants which had been 

 crossed during the two previous generations were to 

 those from the plants self -fertilised during many pre- 

 vious generations in height as 100 to 90. These two 

 lots of seeds were likewise tried by being sown under 

 very unfavourable conditions in poor exhausted soil, and 

 the plants whose grandparents and great-grandparents 

 had been crossed showed in an unmistakable manner 

 their superior constitutional vigour. In this case, as 

 in that of the heartsease, there could be no doubt that 



