Th 



e 



Journal of Heredity 



(Formerly tlie American Breeders' Magazine) 



Vol. VIII, No. 6 June, 1917 



CONTENTS 



The Biolopy of Twins 243 



Unemployment and Feeblemindedness 248 



Signs of Intelligence 249 



Field Workers' Conference on Eugenics 251 



New Tests for Species and Hybrids 251 



Breeding Southern Grapes, by L. R. Detjen 252 



The Selection of Naval Officers 258 



Delinquency in City and Country 258 



Dr. Salmon Appointed on Immigration Ccmmittee 258 



The Celibacy of Teachers 259 



The Status of the Presence and Absence Hypothesis, by John Belling 260 



A New Strain of Hybrid Sheep 260 



Brains and Social Status 261 



Methods of Investigation in Applied Sociology 267 



Urban Sterilization 268 



Degenerate Plants, by Byron D. Halsted 270 



The Extremes of Intelligence in School Children 276 



An Office-Holding Family, by Merton T. Goodrich 277 



The Inheritance of Arithmetical Abilities 283 



Lectures on Heredity in Washington 283 



A Lemon Bud Variation, by A. D. Shamel 284 



How Bees Recognize Each Other 285 



Body and Mind . , 286 



The Essence of Mendeliam, by Joiin Belling 288 



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 send 25 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 

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

 price of single copies. 25 cents. 



Entered as second-class matter February 24, 1915, at the postoffice at Washing- 

 ton, D. C, under the act of August 24, 1912. Contents copyrighted 1917 by the 

 American Genetic Association. Reproduction of articles or parts of 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. May 25, 1917. 



