PROBLEM OF HIGHER FECUNDITY 103 



this is accomplished in one cross. Experiments at the 

 Oregon Station showed that crossing Barred Plymouth 

 Rocks and White Leghorns gave a decided increase in yield, 

 but a still more decided increase was obtained by following 

 up the crossing with selection. Crossing alone was not suf- 

 ficient, Only by high constitutional vigor, aided by selec- 

 tion, can the highest production be secured. 



WHITE LEGHORNS FIRST YEAR, CROSSES IN SUBSEQUENT YEARS 

 PRODUCTION FIRST YEAR OF LAYING 



Per cent laying 

 Tear hens year Hig1iefit L West ^0 eggs or 



1908-09 50 106.9 183 2 0.00 



1909-10 63 135.6 211 14 4.76 



1910-11 39 149.5 257 28 15.38 



1912-13 23 218.2 303 124 69.52 



1913-14 50 223.7 278 92 70.60 



In these experiments 50 pure-bred White Leghorns aver- 

 aging 106.9 eggs were crossed promiscuously with Barred 

 Plymouth Rocks that averaged 84.6 eggs. The cross-breds 

 in the first generation averaged 135.6 eggs. Breeding them 

 back to pure-bred Leghorns the pullets with three-fourths 

 Leghorn blood, averaged 149.5. In the latter flock of cross- 

 bred hens, those with records averaging 208 eggs were se- 

 lected for breeding. Five of them were mated to males 

 from a Leghorn hen with record of 229 in her first year 

 and 407 in two years. Three were mated to a cross-bred 

 male of three-fourths Leghorn blood whose dam laid 402 

 eggs in two years. The daughters from these matings 

 averaged 218.2 eggs, one of them laying 303 eggs. In the 

 next year (breeding females of the same grade were used 

 three-fourths Leghorn blood, average production 385 eggs 

 per hen in two years, dams' dam 402 eggs in two years. 

 These were mated to a pure-bred Barred Rock male whose 

 dam laid 204 eggs in one year and sire's dam 218. The 



