324 THE STRUCTURE OF FLOWERS. 



Iteseda odorata. The results of plants grown in jDots 

 were as follows, the proportions being taken as before. The 

 heights were as 100 : 82; weights as 100 : 67; while their 

 heights when the plants were grown in the open were as 

 100:105.* 



He next raised seed by crossing some flowers and self- 

 fertilising others on the same plant of a particular semi- 

 self-sterile individual. From these the seedlings gave the 

 following results : heights as 100 : 92 ; weights as 100 : 99 ; 

 fertility as 100 : 100. 



These results show that the differences have practically 

 vanished ; the weight being a much, better test than height, 

 as it points to greater assimilative powers, and leaves nothing 

 to be desired. 



It is difficult, then, to see how Ueseda furnishes data for 

 any argument raised to prove the existence of injuriousness 

 in the self-fertilisation of plants. Indeed, Mr. Darwin him- 

 self observes : " I expected that the seedlings from this 

 semi-self-sterile plant wonld have profited in a higher degree 



* Mr. Darwin remarks upon this result as follows : " We have here 

 the anomalous result of the self-fertilised plants being a little taller 

 than the crossed, of which fact I can offer no explanation. It is, of 

 course, possible, but not probable, that the labels may have been inter- 

 changed by accident " {Cross, etc, p. 121). In my paper (p. 383) referred 

 to I have shown that it was most generally the case that while a close 

 competition in the same pot proved disadvantageous to the self-fertilised 

 seedlings, yet, when they had no competition, the differences were not 

 nearly so marked. There are apparently but two alternatives to 

 appeal to in order to account for the fact that intercrossed plants are 

 not so greatly superior to the self-fertilised when planted in open 

 ground, as when in competition in pots ; viz., either the intercrossed 

 plants become deteriorated on being planted in open ground, which is 

 absurd, or else the self-fertilised must regain or acquire vigour in a 

 relatively greater degree than do the intercrossed, and thus would seem 

 to evince what might be called a greater " elasticity " of growth than 

 their intercrossed competitors. 



