CHAP. IV. 



VIOLA TRICOLOR. 



127 



that the same result would follow in a state of nature even to a 

 greater degree; for my plants grew in ground kept clear of 

 weeds, so that the self-fertilised had to compete only with the 

 crossed plants; whereas the whole surface of the ground is 

 naturally covered with various kinds of plants, all of which 

 have to struggle together for existence. 



The ensuing winter was very severe, and in the following 

 spring (1871) the plants were again examined. All the self- 

 fertilised were now dead, with the exception of a single branch on 

 one plant, which bore on its summit a minute rosette of leaves 

 about as large as a pea. On the other hand, all the crossed 

 plants without exception were growing vigorously. So that the 

 self-fertilised plants, besides their inferiority in other respects, 

 were more tender. 



Another experiment was now tried for the sake of ascertaining 

 how far the superiority of the crossed plants, or to speak more 

 correctly, the inferiority of the self-fertilised plants, would be 

 transmitted to their offspring. The one crossed and one self- 

 fertilised plant, which were first raised, had been turned out of 

 their pot and planted in the open ground. Both produced an 

 abundance of very fine capsules, from which fact we may safely 

 conclude that they had been cross-fertilised by insects. Seeds 

 from both, after germinating on sand, were planted in pairs on 

 the opposite sides of three pots. The naturally crossed seedlings 



TABLE 



Viola tricolor : seedlings from crossed and self-fertilised Plants, the 

 parents of both sets having been left to be naturally fertilised. 



