436 
Journal of Agricultural Research 
Vol. V, No. 10 
It will be noted that the Barred Plymouth Rock means are higher 
throughout than are the total flock means. This merely signifies that 
in the total flocks are included many crossbred birds carrying low fecun¬ 
dity genes. 
Turning to the coefficients of variation, which measure the relative 
variability, it is seen that in every case but one (total flock, 1911) the 
coefficient is lower for the March 1 than it is for the 300-day measure. 
The differences are, in the single instances taken by themselves, usually 
not statistically significant, having regard to the probable errors; but 
the general trend is unmistakably in the direction of a lower relative 
variability of the production to March 1, indicating again that this is 
a somewhat better measure of the winter cycle than the production to 
300 days of age under the conditions prevailing in this work. 
SUMMARY 
In this paper quantitative evidence is presented which shows, with 
flocks of poultry having average hatching dates falling somewhere within 
the month of April, that— 
(1) The correlation between the egg production to March 1 of the 
pullet year as one variable and the egg production up to the time when 
the individual is 300 days of age as the second variable is extremely high. 
(2) * The mean production to March 1 is, in general, higher than the 
mean production to 300 days of age. 
(3) The production to March 1 is a relatively less variable measure 
(as indicated by the coefficient of variation) than the production to 300 
days of age. 
(4) The conclusion that the 300-day production would be a better 
measure of the winter cycle of fecundity than the production to March 
1 is not warranted by the facts. Whatever superiority there is of one 
of these measures over the other is entirely in favor of the production 
to March 1. We may therefore conclude that the use, in the writer's 
investigations on fecundity, of the record of egg production to March 1 
of the pullet year as a measure of the winter cycle of production is fully 
justified by a critical examination of the facts. The justification for the 
employment of the winter cycle of production as an index of innate 
fecundity capacity or ability is a distinct and separate problem which 
has been discussed at length in earlier papers. 
LITERATURE CITED 
(1) Brown, Wil. 
1914. Report of second twelve months poultry laying competition, 1913-1914, 
at Harper Adams Agricultural College, Newport, Salop. In Field 
Exp. Harper Adams Agr. Coll. Newport, Salop, Joint Rpt. 1914, p. 7- 
81. 
