XXI.] WHY VARIETIES ARE SELF -STERILE. 353 



planted in isolated or unmixed blocks, and the same 

 is true in various degrees of most varieties of native 

 plums. 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 Con- 

 gres, 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, Spitzen- 

 burgh. Northern Spy, Chenango Strawberry, Bell- 

 flower, King, Astrachan, Gravenstein, Rambo, 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 original seedling parent was 

 impotent with itself ; and the fact that some varieties 

 23 suR. 



