38 Pollinafton in Orchards 



Germany, and Miiller Thirgau at Zurich, who have written several papers 

 on " Parthenocarpie "^ — an expressive term which we owe to France. 



Meaning of Terms " Self-sterile " and " Self -fertile.'''' The terms 

 " self-sterile " and " self-fertile " have been somewhat loosely applied 

 in connection with this subject. In the strictest sense, self-sterility 

 would mean that, although normal ovules were produced, without the 

 intervention of pollen from another variety of the same kind, they would 

 stop development at the egg-cell stage, and no seeds would be produced ; 

 conversely, in self-fertile varieties, the pollen from the same flower, 

 or from a neighbouring flower on the same tree, would fertilize the egg- 

 cell, and seeds would be produced. 



We have purposely said " another variety," not " another plant," 

 because the different trees of, say, " Cox's Orange Pippin " apple are 

 all parts of the original tree which was raised at Colne in Middlesex, 

 just as all the trees of " William's Bon Chretien " pear in all parts of 

 the world (it is called " Bartlett " in America) are all parts of one, 

 propagated by vegetative methods. The diflterent trees of one variety 

 are, although they have a certain individuality of their own, not indi- 

 viduals in the same sense as plants raised directly from seeds would 

 usually be. The varieties of fruit trees are comparable with separately 

 raised seedlings. All the trees of the apple " Blenheim Orange " are, 

 for our purpose, but parts of one individual, all those of " King of the 

 Pippins " of another, all those of " Ribston Pippin " of another, and 

 so on. 



This is the usual meaning of self-sterility in animals and in other 

 plants, but with the fruit-grower the term has another significance. 

 The important point for him is whether or not the fleshy envelope of 

 the seed is matured — the seed itself concerns him not at all, and we find 

 that a considerable number of varieties of apple and pear produce perfect 

 fruits, except that they are seedless, when pollen of other varieties has 

 no access to the stigmas. I have used the term " self-fruitful " for the 

 production of fruit without the intervention of foreign pollen, whether 

 seed is produced or not. Seedless apples and pears are by no means 

 uncommon. They may be found any year, in any orchard, produced 

 from summer flowers. They are common in such varieties as " Lord 

 Derby " and " Golden Spire," when these varieties are not open to 

 pollination by other varieties, for these are self-fruitful, though not 

 self-fertile. They are normal in the pear " Ruyshe's Coreless " and 

 in the apple " No-pip." 



