CROSSING PRODUCTION AND EXHIBITION BIRDS 13 



common in the female offspring. Only 19 per cent of the males were smutty 

 compared with 35 per cent of the females. Under color was also somewhat 

 lighter in the females. 



In the class 6 back-cross population, the greater proportion of both males and 

 females with dark under color were free from smut. Smut was more prevalent 

 in birds with medium or light under color. As a whole, 58 per cent of the males 

 and 41 per cent of the females were smutty. Under color was darker than that 

 of the class 5 progeny of production males mated to Fi females. 



The back-cross progeny from production males, class 7, were about 50 per 

 cent smutty in each sex. The data are inadequate to bring out any relation 

 between smut and under color. 



The class 8 progeny from back crossing F2 females with exhibition males gave 

 only medium and dark under color. These progeny were essentially the same 

 in under color as the exhibition stock; but the females were equally divided into 

 smut and non-smut classes, while exhibition females were very low in smut. 



The general results of the study of the relation of under color and smut in 

 these hybrid offspring showed some evidence that sex-linked dominant genes 

 are concerned in the transmission of smut, that smut in under color may lighten 

 the shade of red pigment in the feather fluff, and that lighter shades of under 

 color appear to be governed by dominant genes. 



Table 6. -Classification of Exhibition Stock and of Hybrid Offspring 

 According to Under Color and Smut 



Linder Color — Males Under Color — Females 



Very Med- Very Med- 



Light Light ium Dark Light Light ium Dark 



