THE FLOWER AND THE BEE 



maturing before the other, as in many sedges, grasses, and in the 

 Umbelliferoe ; or by self -sterility, as has been illustrated in many 

 fruit-bearing plants. That in perfect flowers the pollen ceases 

 to be potent on its own stigma, or is even poisonous, as in cer- 

 tain orchids, is presumptive evidence that continuous inbreed- 

 ing is injurious. It has been repeatedly shown by experiment 

 that crossing results in the addition of new characters and in- 

 creased variability, of greater fertility or the production of 

 more and better seed, and in greater racial vigor of the off- 

 spring. In pears and apples crossed fruit was better-colored, 

 larger, and contained many well-developed seeds, while self- 

 fertilized fruit was much smaller and seedless or contained only 

 vestigial seeds. Coville found that self-pollinated blueberries 

 were smaller and later in ripening; and further examples might 

 be multiplied indefinitely. The evil effects of inbreeding finally 

 show themselves in decreased racial vigor, size, and fertility. 



Most of the arguments against the value of crossing on ex- 

 amination prove to be specious. Its opponents point to the 

 commonness of close or self-pollination; and it is assumed that 

 the two methods must be antagonistic. In reality they are 

 supplementary, and the great number of flowering plants, or 

 Angiosperms, is in part due to each. Where a species is very 

 rare and is represented by only a few individi^ls widely scat- 

 tered, without self-fertilization it would speedily disappear, 

 since crossing would often fail to occur. Again, where there 

 are large areas covered with great sheets of bloom there are not 

 sufficient insects to cross-pollinate all the flowers. It is better 

 for a plant to be self-pollinated than not pollinated at all. In 

 the development of both plants and animals there are not a 

 few, which have become adapted to special locations or con- 

 ditions, where they can live on almost indefinitely under self- 

 fertilization, making no advance or even slowly retrograding. 



276 



