PROCEEDINGS OF THE SUMMER MEETING. 83 



blocks, and the same is true in various degrees of most varieties of native 

 plum. Of the pears which have so far been studied in this connection, 

 the self-sterile are Bartlett, Anjou, Clapp Favorite, Clairgeau, Sheldon, 

 Lawrence, Mount Vernon, Gansel Bergamotte, Superfin, Pound, Howell, 

 Boussock, Louise Bonne de Jersey, Souvenir du Congress, Columbia, 

 Winter Nelis, Bosc, Jones' Seedling, Easter, and Gray Doyenne. Those 

 which appear to be self-fertile are White Doyenne, Le Conte, Kieffer, 

 Duchess, Seckel, Buffum, Manning Elizabeth, Flemish Beauty, and Tyson. 

 Among the apples the following are found to be self-sterile: Talman 

 Sweet, Spitzenburgh, Northern Spy, Chenango Strawberry, Bellflower, 

 King, Astrachan, Gravenstein, Eambo, Roxbury Russet, Norton Melon, 

 and Primate; while Codlin (partially), Baldwin, and Greening are self- 

 fertile. These are results obtained by M. B. Waite, who has brought this 

 investigation to the fore. 



At first thought this fact, that varieties may be self- sterile, looks strange, 

 but it is after all what we should expect, because any variety of tree fruits, 

 being propagated by buds, is really but a multiplication of one original 

 plant, and all the trees which spring from this original are expected to 

 reproduce its characters. If this original tree was self-sterile, therefore, 

 we should expect all trees propagated from it to be equally so, in just the 

 same way that we expect all plants of the Haverland strawberry to be 

 pistillate, like the original parent. To say that any variety of fruit is 

 impotent with itself, therefore, is really the same as saying that the origi- 

 nal seedling parent was impotent with itself; and the fact that some varie- 

 ties are impotent while others are not is proof that fruits vary or differ in 

 this respect when grown from seeds. Perhaps there are as few impotent 

 fruit trees now as there ever were, and that our attention is now called to 

 them simply because they have been propagated or multiplied extensively, 

 and because we are now inquiring carefully into all horticultural problems; 

 but I am inclined to think, from reasons aleady advanced, that there must 

 be a general tendency toward self-sterility. The natural check to this 

 self-sterility is the raising of plants from seeds, by which means a consid- 

 erable amount of variation is secured in sexual characters. In proof of 

 this, I will cite the case of garden vegetables, in which the various indi- 

 viduals of a variety are fertile with each other, even when a given 

 individual is sterile with itself. Thus blocks of the same variety of tomato 

 or bean fertilize freely. But while this same intra-varietal fertility would 

 undoubtedly result from growing only from unbudded or ungrafted fruit 

 trees, the disadvantage, as every one knows, would be so great as to make 

 the practice unprofitable. But the same result can be obtained by planting 

 different named varieties together, for these varieties represent different 

 seed parents. And this is the conclusion which the best practice enforces, 

 for mixed orchards are, as a rule, the most successful ones. 



SUMMARY. 



A broad epitome of the whole problem seems to run something like this: 

 There is a general tendency in nature toward a separation of the sexes, or 

 unisexuality, and tendency is probably hastened among plants by high 

 cultivation. The first signs of separation, and beyond which most plants 

 may never go, are differences in the time of maturity of the sex elements 

 and the failure of pollen to impregnate several flowers. Subsequent steps 

 are the failure of many normal flowers to set fruit and diminution of the 



