798 Journal of Agricultural Research vol. vi, No. ao 



The next type of mating was made with a short-eared male (No. 422), 

 who was one of the pair of twins out of No. 127 by her son, and there- 

 fore her grandson. No. 422 was therefore simplex. He was bred to 

 female 256, a simplex offspring of the first back cross (No. 3 X 127), 

 and also to 127, who was simplex. These matings, being simplex X sim- 

 plex, correspond to a mating of V x and should give the 3 to 1 ratio. Four 

 offspring were obtained from these matings, three of which had short 

 ears and one long, thus giving results again conforming numerically to 

 theory as regards segregation of a simple Mendelian dominant charac- 

 ter. The following diagram shows the various matings and their re- 

 sults. S indicates short ear; L, long ear. 



_>. _ . f Paren t < ? 3L X Parent 9 69S - T 



F 1 offspring^ — ^ ° n 5 — ~ ^- = 3 S : oL 



r b \ 9127S 9222S 9254S ° 



Backcross: r <y 3 LX9i2 7 S c? 3 6iLX9i27S c _ 



Simplex X recess 1 ve{-^ pr ^^s-T3TiS-9l^ 9459^ 9 46oL = ^ : 3^ 



Ir 1 vx ♦ * a • / Ja5sLX9i27S Q T 

 Simplex X extracted recessivei -5 g — -= l ==i i 



*•. - v . . f J422SX9256S <^ 4 22SX9l27S 

 Simplex X simplex( ?573S $46iS $462L ^^ = 3 S : iL 



Cross: 

 Cross: 



While the experiment has been discontinued at this Station, a few 

 more data have become available this spring, as No. 127 was again 

 bred to a pure long-eared ram, though with the primary purpose of 

 studying her performance as a twin bearer. She again dropped twins, 

 a long-eared and a short-eared individual, which further establishes her 

 simplex character with regard to the short-ear trait. No. 462 dropped 

 her first lamb this year. As she is a pure recessive and bred to long- 

 eared sire, a long-eared offspring was the result, as expected. 



No. 422 and 572 were sent to Dr. C. B. Davenport, 1 of the Station 

 for Experimental Evolution, of the Carnegie Institute, who bred the 

 two and also bred the male to 12 long-eared females. Dr. Davenport re- 

 ports that the 12 ewes bred to No. 422 all lambed, 10 of them having 

 dropped twins and 2 of them triplets, the short-ear trait appearing in 

 about one-half of the offspring, which supports previous data indicating 

 his simplex character with regard to short ears. 



1 Acknowledgments are due to Dr. Davenport for valuable advice given during the prosecution of this 

 work. 



