48 EXPERIMENT STATION RECORD. 



be uarrower and not well filled out towards the blossom end, dne 

 principally to lack of development of the ovules. Some varieties, how- 

 ever, are capable of producing perfect fruit without the fecundation of 

 the ovules. In fact, most of the close-pollinated fruit was entirely- 

 seedless. There was a tendency in self-pollinated fruit to be slightly 

 later in ripening than the crosses, as well as being somewhat smaller. 

 In comparing the crosses with each other but slight differences were 

 noted. The difference between the seeds of the two was the most 

 marked. The self- pollinated fruit was seedless or nearly so. The 

 external characters of cross-pollinated and close-pollinated fruit, 

 together with the seed characters, enable one readily to judge to which 

 class a given fruit belongs. 



The author considers the effect exerted on fruit production by the 

 vegetative vigor of the tree, the influence of weather during flower- 

 ing time, the time of blooming of different varieties, of insect visitors, 

 and of diseases. 



Similar experiments were conducted on the apple and quince. The 

 varieties of apple are more inclined to be sterile to their own pollen 

 than is the case of the pears. In the majority of cases no fruit resulted 

 from self-pollination. The quince seemed to fruit as well with its own 

 pollen as with that of another variety. 



The following summary and practical conclusions are given by the 

 author : 



"(1) Many of the common varieties of pears require cross pollination, being par- 

 tially 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 tiian from the same tree. This failure 

 to fruit is due to the sterility of the jjollen and not to mechanical causes. 



"(4) The impotency of the polleu 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 aad its general environment affect 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 polleu. 



"(8) Bad weather during flowering time has a decidedly injurious influence on 

 fruitage by keeping away insect visitors and also by affecting the fecundation of 

 the flowers; conversely, fine weather favors cross pollination and the setting of 

 fruit. 



"(9) Pears produced by self-fertilization are very uniform in shape. They differ 

 from crosses not only in size and shape, but also in some cases in time of maturity 

 and in flavor. 



"(10) Among the crosses the differences were slight or variable, so that their 

 variations are not to be ascribed with certainty to differences in pollen. 



"(11) Self-fecundated pears are deficient in seeds, usually having only abortive 

 seeds, while the crosses are well supplied with sound seeds. 



"(12) Even with those varieties which are capable of self-fecundation the polleu 

 of another variety is prepotent, and unless the entrance of foreign pollen be pre- 



