56 TECHNICAL BULLETIN 7 



Work Already Doxe. 

 By Other Investufntors. 



Bateson (1902) and Hurst (1905) both present data (in crosses between 

 broody and non-broody races, indicating tbat l)roodiness is a dominant cbar- 

 HCter. No furtber information was obtained at tliat time. 



Punnett and Bailey (1920) report some results using Black Langslians, 

 Brown Legborns and Gold-pencilled Haiiilnirgs. Results: 



Langsban $ x Leghorn $ gave all F,* pullets broody. Of the F.* genera- 

 tion 16 pullets were retained, 8 of which went liroody as pullets. Punnett 

 states tluit if the Langshans were of composition A ABB and Leghorns aabb, 

 F, should give 9 broody to 7 non-broody, a close approximation to actual ratio. 

 The reciprocal cross, Legliorn $ x Langsban $ gave all broody in F„ l)ut in 

 F. there were but 19 broody to 47 non-broody. Most of these birds were re- 

 tained but one year. A few that were kept the second year added more 

 broodiness so that the ratio is not 9 to 7, probably because of delayed appear- 

 ance of broodiness. 



In the Hamburg-Langshan cross, the Fi hens were either non-l)roody or 

 showed very little broodiness. Of 38 Fo pullets, 4 were broody, 34 non-broody. 

 Tliese results suggest a third jfactor, N, which inhibits. Fj birds would l)e 

 NnAaCc, but factor N did not inhibit in all cases. The Fo ratio gave 4 

 broody to 34 non-broody. Punnett states that his results are far from con- 

 clusive as to the true nature of the l)roody trait. 



Pearl (1914) found much less broodiness in Barred Plymouth Rocks tiian 

 exists in Reds. His method of measuring the intensity of broodiness was l>y 

 the length of non-productive period. Otlier known factors, sucli as winter 

 pause and molt make such a measure subject to error. 



Work Done by the Massachusetts Station. 



Goodale began the study of this trait in 1912. From that time up to 1921, 

 when he severed his connections with the Station, very satisfactory ])rogress 

 was made in eliminating the tendency from the egg-laying strain of Rhode 

 Island Rcds.t 



Recent M'ork at the Massachusetts Agricultural Experiment Station. 



In the fall of 1922 the writer took up this project using the same general 

 plan with some modifications. The non-broody strain has been carried along 

 witii the intense broody strain and not as a part of tiie general flock in so 

 far as the matings are concerned. The non-broody birds are now being carried 

 along through the second and third laying years to definitely test their l)e- 

 havior with regard to broodiness. Similarly, the breeding males are being 

 carried over and tested for genetic composition. In a paper entitled, "In- 

 breeding the Rhode Island Red Fowl with Si)ecial Reference to Winter Egg 

 I'roduction," the broody trait has been shown to confirm Goodale's AC theory 

 which suggests that broodiness is due to the presence of two dominant, auto- 

 somal, complementary genes, A and C. Both must be jiresent to i)roduce 

 broodiness, but either may be carried alone by non-broody birds. 



* Fi and F2 refer to generations one and two. 

 t See Jla-ss. Agri. Expt. Sta. Bull^. 199 and 'ill. 



