6 MASS. EXPERIMENT STATION BULLETIN No. 288 



1929 Generation 



A total of 55 pullets is available in the 1929 generation. These are classified 

 into five color groups and the mean clutcih size of the groups recorded in Table 5. 



Table 5. — Plumage Color and Clutch Size. 



Light Line Dark Line 



Color 



Number Clutch Size Number Clutch Size 



Very light 2 3.75 



Light 24 3.00 



Medium 6 2.71 12 3.03 



Dark 9 2.44 



Standard 2 2.25 



Total 32 23 



These data are consistent, for an increase in degree of plumage color is reg- 

 ularly followed by a decrease in clutch size. 



1930 Generation 



Table 6 shows the same consistent relationship between clutch size and 

 degree of pigmentation as in previous generations. There is some evidence of 

 increased intensity in the dark line, and there is a tendency for medium shade 

 birds in the dark line to excel medium shade birds in the light line, especially 

 during the last two generations of this experiment. 



Cole 



Table 6. — Plumage Color and Clutch Size. 

 Light Line 



Dark Line 



Very light 



Light 



Medium... 



Dark 



Standard.. 

 Total. 



Number Clutch Size 

 



8 5.44 



3 2.87 





 



11 



Number Clutch Size 

 

 



7 3.79 



1 2.40 





 8 



Table 7 shows that the mean age at sexual maturity was slightly greater in 

 the dark line in all generations after the first. Mean winter clutch size of the 

 dark line was also below the light line in all generations. In mean winter pro- 

 duction the light line surpassed in all generations, except the last. In general 

 the data show some superiority of the light line over the dark line in winter in- 

 tensity. The superiority of the light line over the dark line in annual egg pro- 

 duction is not statistically significant in any generation and the light line cannot 

 be considered superior from the standpoint of fecunditj'. 



