The 



Journal of Heredity 



(Formerly the American Breeders' Magazine) 



Vol. VI, No. 12 December, 1915 



CONTENTS 



Ice Melting from a Twig— Frontispiece 5^^ 



What is a Breed?, by Orren Lloyd-Jones 531 



537 

 Studies of Citrous Fruits 



Value of Negative Eugenics, by Edwin G. Conklin 538 



New Publications: , t tt 



The American Pet Stock Standard of Perfection, by J. "enri^^^ 



"Wagner 



Inheritance of a Profde 



The Marking Factor in Sunflowers, by T. D. A. Cockerell 542 



Inheritance of Sex in Strawberries ^ 



Natural Selection in War, by Roswell II. Johnson 546 



,. . ^ ,, 548 



Pure Lines in Cotton 



The Self-Sterility Problem, by E. J. Kraus 549 



Home Grown or Foreign Seed 



Plant Breeding in Cuba, by F. S. Earle and Wilson Popenoe 558 



Genetic Study of Apples 



. , , 569 



Rebuilding the Leghorn 



Title Page of Vol VI '^'^ 



Index to Vol. VI 



The Journal of Heredity is published monthly by the American Genetic 

 Association (formerly called the American Breeders' Association) for the benefit 

 of its members. Canadian members who desire to receive it should send2o cents 

 a year in addition to their regular membership dues of $2. because of additional 

 postage on the magazine; foreign members pay 50 cents extra for the same 

 Subscription price to non-members, $2.00 a year, foreign postage extra; 



reason. 



price of single copies, 25 cents. ^ a- ^ -ijt u- 



Entered as second-class matter February 24, 191., at the postoffice at Washing- 

 ton D C, under the act of August 24, 1912. Contents copyrighted 19 o by the 

 American Genetic Association. Reproduction of articles or parts o^ articles 

 permitted provided proper credit is given to author and to the Journal of Heredity 

 (Organ of the American Genetic Association), Washington, D. C. 



Date of issue of this number, November 26, 1915. 



