558 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



The practical conclusions are : — 



1. . Plant mixed orchards, or at least avoid planting solid blocks of 

 one variety of pear. It is not desirable to have more than three or 

 four rows of one variety, unless experience has shown it to be perfectly 

 self-fertile. 



2. Where large blocks of trees of one variety which blossomed wel] 

 have failed to fruit for a series of years without any apparent reason, 

 it is exceedingly probable that the failure is due to lack of cross-pollina- 

 tion. The remedy is to graft in other varieties and thus supply foreign 

 pollen. In the case of a solitary pear tree in a garden not fruiting, it 

 may be wise to plant another pear tree of a different variety, but blos- 

 soming about the same time. 



3. Be sure that there are sufficient bees in the neighbourhood to 

 properly visit the blossoms. When feasible, endeavour to favour insect 

 visits to the blossoms by selecting sheltered situations or by planting 

 wind-breaks. 



The quince, which flowers later than the pear, seems to fruit nearly 

 as well with its own pollen as with that of another variety; whereas 

 apples were found to be more inclined to be sterile to their own pollen 

 than pears, in the great majority no fruit resulting from self-pollina- 

 tion. 



Mr. F. J. Chittenden,* now Director of the Eesearch Station of 

 the Royal Horticultural Society, in 1902 and 1903, in Essex, tested | 

 fifteen varieties of pears to see whether they would set fruit with their 

 own pollen. The only two varieties that set fruit were ' Conference ' and 

 ' Durondeau.' The other varieties requiring cross-pollination were: — 

 ' Beurre d'Amalis,' * Beurre Superfin,' ' Catillac,* * Doyenn^ du , 

 Comice, ' * Easter Beurr^,' ' Emile d'Heyst,' * Jargonelle,' ' Josephine 

 de Malines,' 'Louise Bonne of Jersey,' 'Williams' Bon Chretien,' 

 ' Olivier de Serres,' ' Bellissime d'Hiver, ' and ' Pitmaston Duchess • 

 the last two varieties in the second year did set one fruit out of eighteen , 

 and out of twelve respectively. ' 



Mr. Chittenden's experiments prove that among pears the propor- 

 tion of self-sterile varieties is quite as large in England as in America. 



About eighteen years ago, when farming at Swanley, I planted 

 forty bush * Pitmaston Duchess ' pears, which for four years, although 

 flowering well, did not fruit; I therefore removed them to another 

 field about a third of a mile distant, and planted othe-r varieties with 

 them, putting a hive of bees on the border of the plantation. The 

 following year the trees bore a fair quantity of fruit, and have con- 

 tinued to do so with fair regularity since. The probable reason of their I 

 failure at first was lack of foreign pollen. 



The impotence of the pollen to fertilize another flower of its own 

 variety is not due to any deficiency of its own, but to the lack of affinity 

 between the pollen and the ovules of the same variety. The pollen of 

 two varieties may be absolutely self-sterile and at the same time per- 



* Journal R.H.S. vol. xxvii. (1902), p. rxc. and vol. xxviii. (1903), p. clxvi. 



