CONCLUSIONS. 



81 



paper, cheese cloth, or nettiug with meshes (ten to the inch) were 

 l^laced over the nnopened buds and outside pollen thus excluded; and 

 (2) careful hand-pollinations of flowers which were emasculated while 

 yet in bud and protected from all other pollen by paper bags. Tliese 

 experiments were carried on in large numbers and at four different places 

 viz, at Brockport, in 1891; and at Scotland, Eochester, and Geneva, 

 iu 1892. The conditions of the trees were widely different, as was also 

 the weather at flowering time. The work was done on a large number 

 of varieties of pears, several of which occurred in all four of the series 

 of experiments. The results under these varying conditions have sub- 

 stantially agreed, in most cases being remarkably uniform. The fruits 

 resulting from the different kinds of i^ollen showed interesting differ- 

 ences, which tend to corroborate the conclusions. 



It should also be noted that similar experiments were tried on the 

 apple and the quince along with the pear work. The varieties of apples 

 are more inclined to be sterile to their own pollen than the pears. With 

 the former in the great majority of cases no fruit resulted from self-pol- 

 lination. The results as a rule, however, were less clear cut than in the 

 pear, because with most of the self-sterile varieties an occasional fruit 

 will set under self-pollination, and none of the varieties were very com- 

 pletely self-fertile. The quince, on the other hand, seeuis to fruit 

 nearly as well with its own pollen as with that of another variety. 



The following conclusions are, it is thought, fully warranted from 

 the evidence which has been given, and doubtless many who read this 

 will recall observations in i)ractical orcharding which give further 

 support : 



(1) Many of the common varieties of pears require cross ])ollination, 

 being partially or wholly incapable of setting fruit when limited to 

 their own pollen. 



(2) Some varieties are capable of self-fertilization. 



(3) Cross-pollination is not accomplished by applying pollen from 

 another tree of the same grafted variety, but is secured by using 

 pollen from a tree of a distinct horticultural variety, i. e., which has 

 grown from a distinct seed. Pollen from another tree of the same 

 variety is no better than from the same tree. This failure to fruit is 

 due to the sterility of the pollen and not to mechanical causes. 



(4) The impotency of the pollen 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. 



(5) The pollen of two varieties may be absolutely self-sterile and at 

 the same time perfectly cross-fertile. 



(6) The state of nutrition of the tree and its general environment 

 affects its ability to set fruit either with its own pollen or that of another 

 tree. 



(7) Bees and other insects are the agents for the transportation of 

 pollen. 



11876— No. 5 6 



