New York Agkicultukal Extkkiment Station. 487 



combinations of characters. Prodncing new combinations of 

 characters by crossing is but a small part of the work of securing 

 superior varieties of apples. The task of selecting different 

 combinations of unit characters in the progenies of crosses is a 

 tremendous one, requiring knowledge of the many varieties of 

 apples, of all characters of apples and of what ones combined will 

 make a variety superior to existing sorts. It is likely that the 

 greatest part of the work in breeding apples is, or will be when 

 the foundation for breeding is more firmly laid, this selection 

 among the manifold combination of characters that can be made. 

 Following in Mendel's footsteps, we have a quicker route to the 

 desired results in breeding apples, but breeding will still be 

 laborious, slow and disappointing, differing chiefly from that of 

 the past in being now a problem and not of as old, a riddle. 



How can Mendelian principles be made most serviceable to 

 breeders of apples ? The aim in breeding is to produce varieties 

 with the greatest number of desirable characters and the least 

 number of undesirable ones. Mendel has shown that characters 

 are transmitted as units which segregate in accordance with a 

 definite formula. It remains, then, for the breeder to 'take cer- 

 tain characters from one parent, others from another, and make 

 as many combinations as possible from which the best can be 

 selected. The first task is to determine how characters are 

 inherited, after which they can be associated or disassociated 

 somewhat as the breeder wishes. The behavior of the crosses in 

 this experiment gives some indications of how certain characters 

 are transmitted when found in the varieties involved and forms 

 a basis, therefore, for breeding work with these varieties, and 

 suggests, at least, how the characters discussed will behave in 

 other varieties that may be crossed. 



The application of Mendelian principles to breeding apples, 

 as with other plants, will not be free from puzzling problems. 

 Some of these may be briefly stated. 



The determination of the factors by which the various charac- 

 ters are transmitted will prove a very difficult task. If all were 

 simple characlors depending upon a single factor, the work would 

 be greatly simplified, but it is likely that we shall find that some 

 of tlie most important characters of apples depend upon the 



