Dec. 6, 1915 
Egg Production of Domestic Fowl 
435 
ever for the assertion that the record to 300 days of age is a better meas¬ 
ure of the winter-cycle production than is the record to March 1, so far 
as concerns the flocks which have been used in the writer's investigations 
of fecundity. Of course, it might possibly be that if one did the bulk of 
his hatching very late in the season, so that the pullets were not properly 
matured in the fall, then the 300-day record might be more reliable than 
the March 1 record. Tables I to VII demonstrate, however, that there 
is no distinct or marked superiority of one of these measures over the 
other when the flocks are bred and managed as those of the Maine Station 
have been during the last eight years. 
We may turn now to an examination of the variation constants for the 
two measures. These are shown in Table VIII. 
Table VIII .—Variation constants for (a) egg production to March I, and ( b ) egg pro¬ 
duction to 300 days of age 
EGGS LAID BEFORE MARCH I 
Year. 
Flock. 
Mean. 
Standard 
deviation. 
Coefficient of 
variation. 
1911. -•• 
Barred Plymouth Rock. 
43 - I 3 ± a 97 
20. 26 ±0. 69 
46. 98 ± I. 91 
1911.... 
Total. 
32. 4 S± .67 
21. 53 ± .48 
67. 26 ±2. 06 
1912 
Barred Plymouth Rock. 
48. 41 ± 1. 04 
21. 83 ± .74 
45 -° 9 ± i - 81 
1912.... 
Total. 
36. 24± . 68 
22. 09± . 48 
60. 96cbi. 75 
I 9 I 3 - 
Barred Plymouth Rock. 
26. 39± . 85 
44 - 44 ±i. 7 ° 
I 9 I 3 * ••• 
Total. 
47. 68 ± .89 
28.851b .63 
60. 51 ± 1. 74 
EGGS LAID BEFORE 300 DAYS OF AGE 
1911.... 
Barred Plymouth Rock. 
34 - 39±°- 8 3 
17. 4 °±o. 59 
50. 6odb2. 10 
1911.... 
Total. 
27.09J: . 56 
i 7 - 7 <>± -39 
65/57 ± 1. 98 
1912.... 
Barred Plymouth Rock. 
35 - 97 ± - 9 i 
19.11 ± .65 
53. 12 ±2. 25 
1912.... 
Total.... 
28. 28 ± .56 
18. i5± . 39 
64. 16 ± 1. 39 
1913.... 
Barred Plymouth Rock... 
54 - 5 6 ± 1 - 12 
24.38J: . 79 
44. 68 ± 1. 7 1 
1913.... 
Total. 
42. 38 ± .83 
26. 92 ± .39 
63. 53 ± 1. 86 
From Table VIII it is apparent that, in the first place, the mean 
production for the 300-days-of-age group is uniformly below the mean 
production to March 1. Since the latter period can hardly be regarded 
as essentially overestimating the winter cycle, as judged on the basis 
of curves of the distribution of production through the year (9), clearly 
the 300-day grouping must somewhat underestimate in the case of 
flocks with a mean hatching date falling in the month of April. All 
the flocks which have been used in the study of fecundity at the Maine 
Station and on which all of our conclusions have been based have their 
mean date of hatching in the month of April. It is therefore plain that 
the 300-day measure can not in this respect be considered so good a 
measure of the winter cycle under the conditions prevailing in the 
writer's investigations as the March 1 measure. 
