4 MASS. EXPERIMENT STATION BULLETIN 301 



nine-year period indicates that the linkage between broody genes and high in- 

 tensity genes is sufficiently weak to allow much crossing over, so that non-broody 

 birds with high intensity occur frequently and were selected as breeders in this 

 experiment. Such a condition exists abundantly in Leghorns which may have had 

 a similar evolutionary history. 



Table 2. Mean Winter Clutch Size in Non-Broody and Broody Lines. 



3. Winter Pause Duration 



Winter pause represents a period of non-production between November first 

 and March first of the pullet year. Hays and Sanborn (1927, loc. cit.) have shown 

 the net correlation between total days broody and winter pause duration to be 

 — ■1609+ .0245, which indicates a slight tendency for high intensity of broodiness 

 to be associated with short winter pause. 



Table 3 presents the mean winter pause length by years for all birds in the two 

 lines. In general the non-broody line appears to exhibit a shorter pause than the 

 broody line. Tested by Fisher's method the two series of means differ significantly. 



Table 3. 



Mean Winter Pause Duration in Non-Broody and Broody 

 Lines. 



