180 



RAYMOND PEARL 



not be lumped together in calculating means or other constants. 

 So few of the yearhng hens with which the experiment started 

 lived through that there is not enough material to make any 

 critical detailed study of their production. Accordingly we may 

 confine our attention to the laying activity of the pullets with 

 which the experiment started. 



In the first column of table 5 are given the monthly mean 

 productions for all treated birds surviving through the indicated 



TABLE 5 

 Mean monMy egg production of treated and control birds. 



November, 1914 



December 



January, 1915. . . 



February 



March 



April 



May 



June 



July 



August 



September 



October 



November 



December 



January, 1916. . . 



Totals 



TREATED 



3.73 



14-91 



12.36 



14-00 



19.54 



16.44 



19.44 



16.89 



13.78 



13.22 



12.33 



9.00 



8.67 



3.33 



6.33 



183.97 



11 



11 



11 



11 



11 



9 



9 



9 



9 



9 



6 



6 



6 



6 



6 



GENER.\L 

 CONTROL 



6.91 



7.91 



12.50 



14.63 



19.48 



18.15 



17.74 



17.08 



16.35 



15.50 



15.33 



13.25 



6.58 



1.00 



2.33 



184.74 



33 

 32 

 32 

 30 

 29 

 27 

 27 

 26 

 26 

 26 

 12 

 12 

 12 

 12 

 9 



SPECIAL 

 CONTROL 



6.91 



7.91 



12.50 



14.63 



19.54 



17.26 



16.79 



16.17 



16.28 



16.06 



15.00 



12.00 



8.00 



1.75 







180.80 



33 



32 



32 



30 



29 



19 



19 



18 



18 



18 



4 



4 



4 



4 



4 



month, beginning with November, 1914, and continuing through 

 January, 1916. No bird which died in the course of the experi- 

 ment is included in the calculation of the mean production for 

 the month in which she died. In the third column of the table, 

 headed 'General Control,' are given the monthly mean produc- 

 tions for all untreated control birds surviving through the indi- 

 cated month. This column represents the distribution of the 

 production of the general control flock, regardless of whether 

 the treated sisters of any of these control birds had died. In 

 the fifth column of the table, headed 'Special Control,' are given 



