xiv CONTENTS 



Page 

 Endosperm — The Setting of the Fruit — What Constitutes a Normal Set of 

 Fruit — The June Drop and Other Drops — The First Drop; the Second Drop; 

 the Third Drop or June Drop — Fruit Setting, Fruitfulness and Fertility 

 Distinguished — Sterility and Unfruitfulness Classified — Summary. 



CHAPTER XXVII 



Unfruitfulness Associated with Internal Factors 489 



Due Principally to Evolutionary Tendencies — Imperfect Flowers, Dioecious 

 and Monoecious Plants; Heterostyly; Dichogamy, Protandry and 

 Protogyny; Impotence from Degenerating or Absorbed Pistils or Ovules; 

 Impotence of Pollen — Due Principally to Genetic Influences — Sterility and 

 Unfruitfulness Due to Hybridity — Incompatibility — Interfruitfulness and 

 Interfertihty; in Reciprocal Crossings — Due Principally to Physiological 

 Influences — Unfruitfulness Due to Slow Growth of the Pollen Tube — Prema- 

 ture or Delayed Pollination — Nutritive Conditions Within the Plant — Effect 

 on Pollen Viability; Effect on Defectiveness of Pistils; Fruit Setting of 

 Flowers in Different Positions; Strong and Weak Spurs; Evidence from 

 Ringing Experiments; Evidence from Starvation Experiments — Summary. 



CHAPTER XXVIII 



Unfruitfulness Associated with External Factors 509 



Nutrient Supply; Pruning and Grafting; Locahty — Season — End-season 

 FertiUty; Change of Sex with Season — Age and Vigor of Plant; Tempera- 

 ture; Light; Disturbed Water Relations; Rain at Blossoming; Wind; Fungous 

 and Bacterial Diseases; Spraying Trees When in Bloom; Other Factors That 

 Cause the Dropping of Fruit and Flowers — Summary. 



CHAPTER XXIX 



Factors more Directly Concerned in the Development of the Fruit . . 521 

 Stimulating Effects of Pollen on Ovarian and Other Tissues; the Effect of 

 Certain Stimulating Agents on Fruit Setting — Seedlessness and Partheno- 

 carpy — Seedlessness of Non-parthenocarpic Fruits; Vegetative and Stimula- 

 tive Parthenocarpy; Relation of Anatomical Structure of Fruit to 

 Parthenocarpy; the Value of Seedless and Parthenocarpic Fruits — The Rela- 

 tion of Seed Formation to Fruit Development — Structure of Fruit; Form; 

 Size; Composition and Quality; Season of Maturity; Specific Influence of 

 Pollen on Resulting Fruit — Summary. 



CHAPTER XXX 



Fruit Setting as an Orchard Problem 538 



The Number of Pollenizers; Temporary Expedients; PoUinating Agents — 

 The Fruit Setting Habits of Different Fruits— Apple; Pear; Quince; Peach; 

 Almond; Plum; Apricot; Cherry; Grape; Strawberry; Currant and Goose- 

 berry; the Brambles; the Nuts; Persimmon — Summary. 



