Reproduction 



371 



Charlamowski apples, and in six varieties of pears, of 

 which the most important is the Clairgeau. In the best 

 of the cases reported by him the fruits suffered neither 

 diminution in size nor change of quality, although parthen- 

 ocarpic development is commonly accompanied by de- 

 creased size. Sections of well-fertilized and seedless 

 fruits are shown in Figure 105. 



Fia. 105. Section of fertile (seed-bearing) and seedless (parthenocarpic) 



apples. 



219 a . Seedlessness in the orange, grape, and banana. 



Well-established varieties of citrus fruits, commercially 

 important, normally produce no seed. The California 

 navel oranges are of this type. In this instance pollina- 

 tion cannot lead to fertilization, since, according to the 

 reports available, the stigmatic surface apparently fails 

 to reach full development, or to become normally exposed, 

 and thus germination and the entrance of the pollen tubes 

 is precluded. Further observations upon this point are 

 needed. 



Historically of more interest are certain cases of par- 



