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 i, 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 i 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. 



Tabi,E VIII. — Variation constants for (a) egg production to March I, and (6) egg pro- 

 duction to joo days of age 



EGGS LAID before; MARCH I 



EGGS LAID BEFORE 300 DAYS OP AGE 



I911. 

 I911. 

 I912. 

 1912. 

 1913- 

 1913- 



Barred Plymouth Rock. 



Total 



Barred Plymouth Rock. 



Total 



Barred Plymouth Rock. 

 Total 



34-394:0.83 



27. 094: . 56 

 3S-97± -91 



28. 28± . 56 

 54- 56±i- 12 

 42.384: .83 



17. 4o4:0. 59 

 17.76^ .39 

 19- II ± -65 



18. is± .39 

 24- 384: . 79 

 26. 92 ± -59 



50. 6o±2. 10 

 65. 57 ±1.98 



53. 12 ±2. 25 

 64. i6±i. 39 

 44. 68±i. 71 

 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 i. 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 i measure. 



