186 University of California Publications in Botany [Vol. 5 



characters, the great majority of which exist in a state of domes- 

 tication, are inherited in Mendelian fashion (cf. Darbishire, 1911, 

 p. 239). On the other hand these same few hundred characters 

 may represent almost the sum total of those which are of inter- 

 est to the practical breeder. When the breeder finds that he is 

 dealing with a Mendelian dominant his heredity "short -hand" is 

 simpler than it ever could have been without the Mendelian nota- 

 tion. If the inheritance of the character he is interested in is 

 more complex — i.e., if it is a "bulk character" — he will follow 

 such obvious suggestions as those given by Castle {loc. cit., p. 

 362). In either case the breeder will probably be primarily in- 

 terested, just as he always has been, in only one thing — i.e., 

 increasing variability by crossing. The value of the JMendelian 

 interpretation for the breeder has from the start been made ap- 

 parent in practice and by no means all the characters which he 

 is interested in and w^hich will "Mendelize" have been dealt 

 with at this time. Likewise the theoretical value for the science 

 of heredity in the Mendelian point of view^ "that the contents 

 of the germ cells and not the outward characteristics of the 

 animals and plants dealt with must be our guide in breeding" 

 cannot be overestimated. No one, it seems to me, can wish "to 

 give up ' ' the Mendelian point of view and its ' ' handy and help- 

 ful notation" especially in those cases in which it is so handy 

 and so helpful. On the other hand with reference to those cases 

 in which, both for the student of the problems of genetics and 

 for the practical breeder, the notation is neither handy nor help- 

 ful, though theoretically capable of application, a question must 

 be answered — i.e., which is the way for progress? 



I am indebted to Professor W. A. Setchell for much helpful 

 suggestion and criticism in connection with the preparation of the 

 above note. 



