302 MASS. EXPERIMENT STATION BULLETIN 258 



In this experiment, inbreeding operated to intensify inherent weaknesses ex- 

 isting in the foundation stock. This trial, therefore, furnishes striking evidence 

 of the importance of most rigorous standards in selecting stock for inbreeding 

 purposes. 



On the whole, these studies furnish no evidence of advantages that may be 

 gained by inbreeding over the ordinary method of flock improvement by rigid 

 selection for characteristics affecting fecundity when close matings are avoided. 

 Since desirable fecundity traits for the most part are transmitted in Mendelian 

 fashion, more satisfactory progress may be made by selection on the unit factor 

 basis rather than on the individual bird basis as is necessary for inbreeding. 



REFERENCES 



Dunn, L. C. 1922. Hatchability and chick mortality. Poultry Sci. 1, No. 2. 



Dunn, L. C. 1923. Experiments on close inbreeding in fowls. Conn. (Storrs) Agr. Expt. Sta. 



Bui. 111. 

 Dunn, L. C. 1927. The effect of inbreeding and cross-breeding on fowls. Verhand. Internat. 



Kong. Vererbungswissenschaft. Berlin, p. 607-617. 

 Goodale, H. D. 1927. Some phases of reproduction in domestic fowl. Proc. World's Poultry 



Congress, p. 87-92. 

 Hays, F. A. 1924. Inbreeding the Rhode Island Red fowl with special reference to winter egg 



production. Amer. Nat. 58: 43-59. 

 Hays, F. A. 1927. The inheritance of persistency and its relation to fecundity. Proc. World's 



Poultry Congress, p. 92-95. 

 Hays, F. A., and Ruby Sanborn. 1924. The inheritance of fertility and hatchability in poultry. 



Mass. Agr. Expt. Sta. Tech. Bui. 6. 

 Hays, F. A., and Ruby Sanborn. 1926. Broodiness in relation to fecundity in the domestic fowl. 



Mass. Agr. Expt. Sta. Tech. Bui. 7. 

 Hays, F. A., and Rubv Sanborn. 1927. Net correlations of characters concerned in fecundity. 



Mass. Agr. Expt. Sta. Tech. Bui. 12. 

 Hays, F. A., and Ruby Sanborn. 1928. Vigor in production-bred flocks. Mass. Agr. Expt. 



Sta. Bui. 242. 

 Jull, M. A. 1924. The relation of antecedent egg production to the sex ratio in the domestic 



fowl. Jour. Agr. Research 28: 199-224. 

 King, Helen D. 1918a. The effects of inbreeding on the growth and variability in the body 



weight of the albino rat. Jour. Expt. Zool. 26: 1-54. 

 King, Helen D. 1918b. The effects of inbreeding on the fertility and on the constitutional vigor 



of the albino rat. Jour. Expt. Zool. 26: 55-98. 

 King, Helen D. 1918c. The effects of inbreeding, with selection, on the sex ratio of the albino 



rat. Jour. Expt. Zool. 27: 1-35. 

 Wright, Sewall. 1922a. Coefficients of inbreeding and relationship. Amer. Nat. 56: 330-338. 

 Wright, Sewall. 1922b. The effects of inbreeding and cross-breeding on guinea pigs. I. DecUne 



in vigor. II. Differentiation among inbred families. U. S. Dept. Agr. Bui. 1090. 

 Wright, Sewall. 1922c. The effects of inbreeding and cross-breeding on guinea pigs. III. Crosses 



between highly inbred families. U. S. Dept. Agr. Bui. 1121. 



Publication of this Document 

 approved by the 

 Commission on Administration and Finance 

 3M— 2— '30. No. 7834 



