Blossom and Seed lyj 



pens that pollen from their own blossom, or from another 

 blossom on the same stalk, does not suit the ovules. 

 Some which are fertiHzed by the pollen of their own blos- 

 som, close-fertiHzed, as it is called, do well, and the seed 

 is plentiful; but in most cases it is poor, and even worth- 

 less. Sometimes the pollen from a blossom on the same 

 stalk actually has the effect of poison, and when applied 

 to the pistil-tip, causes it to shrivel and decay, and makes 

 the petals drop; sometimes, again, it does neither good nor 

 harm directly; it does not poison and it does not fertilize, 

 but — which is equally injurious — it prevents any other 

 pollen received afterwards from having any effect, so that 

 in either case the ovules are equally sure to shrivel. 

 Then, further, there are some plants, as, for instance, 

 certain of the passion-flowers, whose ovules cannot be 

 converted into seeds unless they receive pollen not merely 

 from another plant of the same species, but from another 

 plant of a different species — a passion-flower, but a differ- 

 ent species of passion-flower. 



Such, then, being some of the many arrangements by 

 which it is made difficult or impossible for ovules to be 

 fertilized by pollen from their own blossom, or from a 

 blossom on the same stalk, one must conclude that there 

 is some reason for them, and that seed is the better for 

 being cross-fertilized — fertilized, that is, by pollen from 

 another plant. And so, indeed, it proves; for if cross- 

 fertilized and self-fertilized seeds be sown together, it 

 generally happens that the former grow up so much the 

 stronger as quite to overpower the rest. 



As a rule, then, cross-fertilized seed produces much 

 more vigorous plants than self-fertilized seed does. But 

 still, as wild plants have to keep their own place in the 



