THE ASSOCIATION OF CHARACTERS 253 



and they ripened quite in the ordinary way. All the bright 

 display of broad and shining petals, of honey, and a sweet 

 fragrance is here absolutely useless and superiluous. Moths 

 and bees are attracted in large numbers, but the pollen 

 which they bring to the pistils is of no use at all. 



The evening primrose of Lamarck widely surpasses its 

 congeners in the size of its flowers. In connection with 

 this difference it produces styles of such a length that the 

 stigmas are elevated above the anthers and cannot directly 

 be touched by their pollen. Here no fecundation is possible 

 without the aid of the insects, and if these are experimentally 

 excluded the flowers fade away without making fruit. All 

 the beautiful and ingenious means of attracting insects come 

 into play in this case. No part of the flower is superfluous, 

 as it is in the ordinary species. 



The correlation between size and need of insect aid, 

 however, shows itself as soon as the season draws to its close, 

 or rather as the spikes increase in length. Towards autumn 

 the flowers become steadily smaller and their styles do so 

 too, but in a greater degree. The elevation of the stigmas 

 above the anthers decreases, and in September and October 

 they are touched by the pollen, insuring by this means self- 

 fertiUzation without other aid. The depositing of the pol- 

 len on the stigma is at first only shght and insufficient, but 

 as the summer decUnes it steadily becomes more complete, 

 and in the end the small flowers at the tops of the spikes 

 are as sure to fertiUze themselves as are the brightest blos- 

 soms of the CEn. biennis. 



If now we compare tliis case of correlation with the 

 previously mentioned ones, we see that here we have a de- 

 pendence on external influences, which causes the correla- 

 tion to come into play, whilst in the other instances no such 

 excitement was required. Hence we see that all correla- 

 tions are not of the same nature. Some are the result of 



