CHAPTER XIV 

 SELF-STERILITY 



It has been discovered that many of the races of 

 cultivated plants, notably apples, do not develop viable 

 seed when self-pollinated. The practice adopted by 

 horticulturists, therefore, to meet this situation is to 

 make mixed plantings of several races. In this way 

 foreign pollen is always present, and this results in 

 viable seed where ' ' own ' ' pollen fails. This phenomenon 

 is known as self-sterility and seems to be well established 

 in many cases. 



In connection with this phenomenon the following 

 problem confronts us. Is self-sterility of any advantage 

 to plants in nature, or is it merely a necessary evil that 

 has arisen as a result of culture ; or is it merely mechan- 

 ical or chemical necessity that has arisen in response to 

 certain conditions and is of no significance one way or 

 the other in the economy of plants ? Opinion is divided 

 on this point. Most biologists, however, claim that 

 self-sterility is of some advantage to the plant. This 

 opinion is related of course to belief in the Darwinian 

 doctrine of the survival of the fittest, survival being a 

 proof of usefulness. For this reason it has become 

 customary to regard a plant character as useful until 

 the contrary is proved. This point of view has been of 

 service in the past and is still useful, subject to certain 

 limitations. 



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