286 CONSTITUTIONAL VIGOUR CHAP. VIII. 



After the crossed or the self-fertilised plants had 

 once grown decidedly taller than their opponents, a 

 still increasing advantage would tend to follow 

 from the stronger plants robbing the weaker ones 

 of nourishment and overshadowing them. This was 

 evidently the case with the crossed plants of Viola tri- 

 color, which ultimately quite overwhelmed the self- 

 fertilised. But that the crossed plants have an inherent 

 superiority, independently of competition, was some- 

 times well shown when both lots were planted 

 separately, not far distant from one another, in good 

 soil in the open ground. This was likewise shown in 

 several cases, even with plants growing in close compe- 

 tition with one another, by one of the self-fertilised 

 plants exceeding for a time its crossed opponent, which 

 had been injured by some accident or was at first 

 sickly, but being ultimately conquered by it. The 

 plants of the eighth generation of Ipomoea were raised 

 from small seeds produced by unhealthy parents, and 

 the self-fertilised plants grew at first very rapidly, 

 so that when the plants of both lots were about three 

 feet in height, the mean height of the crossed to that 

 of the self-fertilised was as 100 to 122 ; when they 

 were about six feet high the two lots were very nearly 

 equal, but ultimately when between eight and nine feet 

 in height, the crossed plants asserted their usual 

 superiority, and were to the self-fertilised in height as 

 100 to 85. 



The constitutional superiority of the crossed over the 

 self-fertilised plants was proved in another way in the 

 third generation of Mimulus, by self-fertilised seeds 

 being sown on one side of a pot, and after a certain 

 interval of time crossed seeds on the opposite side. The 

 self-fertilised seedlings thus had (for I ascertained that 

 the seeds germinated simultaneously) a clear advantage 



