ABSTRACTS. 



295 



It is shown that the interpolation method, when third dif- 

 ferences are used, gives values slightly better than those by 

 Forsyth's method when n = 25. For n = 75 or more the inter- 

 polation method using only second differences gives an approxi- 

 mation sufficiently close for all practical statistical purposes. 

 x\s to the labor involved, there is no great amount of choice be- 

 tween Forsyth's and the interpolation method, but on the whole 

 there appears to be a distinct, if small, advantage in favor of 

 the interpolation. 



MENDELIAN INHERITANCE OF FECUNDITY IN 

 THE DOMESTIC FOWL, AND AVERAGE FLOCK 

 PRODUCTION.* 



In this paper it is shown that : 



I. There is a marked difference in average egg production 

 per bird of Barred Plymouth Rock pullets of the Maine Station 

 strain at the present time as compared with what obtained dur- 

 ing the period of simple mass-selection for this character. This 

 is seen in Table I. 



TABLE I. 



Monthly Distribution of Mean Egg Production per Bird under Dif- 

 ferent Breeding Systems 







Best Com- 











' parable 











Year to 









Weighted 



1913-14 of 









Mean 



Similor- 









Under 



sized 



Best Month in Any Year of Mass Selection, 



Year 



Mouth 



Mass 

 Selection 



Flocks Un- 

 der Mass 

 Selection 

 (1905-06 

 100-bird 

 Pens) 



Any Size Flock 



1913-14 



November.. . 



4.63 



5.38 



6.45 (1904-05, 100-hird flock) 



10.76 



December. . . 



8.91 



9.91 



12 .02 (1901-02, only 48 birds in small flocks) 



14.19 



January .... 



11.71 



13.27 



15.21 (1901-02. only 48 birds in small flocks) 



13. S8 



February.. . . 



10.87 



13.39 



14.46 (190.5-06, oO-bird flocks) 



13.37 



March 



16.11 



17.33 



18.29 (190.O-06, 50-bird flocks) 



19.22 



April 



15.85 



16.48 



18.50 (1901-02, only 48 birds in small flocks) 



IS.AA 



May 



13.92 



— . 



17.02 (1902-03, 147 birds in small flocks) 



16.SS 



June 



12.46 



13.47 



16.88 (1901-02, only 48 birds in small flocks) 



U.5G 



July 



10.87 



10.49 



14.93 fl901-02, only 48 birds in small flocks) 



14.02 



*This is an abstract of a paper by Raymond Pearl, having the same 

 title and published in American Naturalist, Vol. XLIX, pp. 306-317, iQiS. 



