Aug. 1, 1925 
Relationship Between Weight of Eggs and Chicks 
225 
case is the difference significant, the differences with their probable 
errors being 0.63 ±0.43, 0.81 ±0.32, 0.11 ±0.43, and 0.68 ±0.25 gm. 
These results would indicate that chicks can not he assorted by sex 
at hatching time according to their weights. 
Table II .—Relationship between the mean weight of male chicks and the mean 
weight of female chicks, in each of four groups; and the relationship of the mean 
weight of male and female chicks, respectively, between the yearling hen and the 
pullet groups of each breed 
Group 
Number 
Mean weight 
of male 
chicks 
Number 
Mean weight 
of female 
chicks 
Difference 
Rhode Island Red yearlings_ 
66 
Gm. 
39.72±0.31 
49 
Gm. 
39.09±0.30 
0.63±0.43 
Rhode Island Red pullets_ 
59 
37.68± . 23 
54 
36.87± . 23 
. 81± . 32 
Difference _ 
2.04± . 39 
2.22± . 38 
Barred Plymouth Rock yearlings_ 
63 
39. 07dh . 28 
49 
38.96± . 33 
. 11± . 43 
Barred Plymouth Rock pullets_ 
123 
37.99± . 18 
106 
37.31dt . 18 
. 68dz . 25 
Difference 
1.08=b . 33 
1.65db . 38 
Table II also shows the relationship between the weights of males 
and females, respectively, obtained from eggs laid by the yearling 
hens and from eggs laid by the pullets for each of the two breeds. 
In the case of the Rhode Island Reds, the difference in the mean 
weight of males from eggs laid by the yearling hens and from eggs 
laid by pullets is 2.04 ±0.39 gm. in favor of the yearling hens, and the 
difference in the mean weight of females from eggs laid by yearling 
hens and from eggs laid by pullets is 2.22 ±0.38 gm. in favor of the 
yearling hens. In the case of the Barred Plymouth Rocks r the 
difference in the mean weight of males from eggs laid by the year¬ 
ling hens and from eggs laid by the pullets is 1.08 ±0.33 gm., and the 
difference in the mean weight of females from eggs laid by yearling 
hens and from eggs laid by pullets is 1.65 ± 0.38 gm. The differences 
are significant m every case, and are what would naturally be 
expected in view of the significant differences in the mean weights of 
eggs laid by the yearling hens and by the pullets, as shown in Table I. 
It might be possible, however, for chicks from eggs laid by pullets 
to be as heavy or even heavier than chicks from eggs laid by yearling 
hens, if the chicks from pullet eggs constitute a higher mean per¬ 
centage of the mean egg weight than the chicks from yearling-hen 
eggs. Such a situation might be true whether the mean weight of 
the pullet eggs was as great or even less, as in the case of this study, 
than the mean weight of the yearling-hen eggs. In other words, do 
all chicks, whether they come from eggs laid by yearling hens or 
from eggs laid by pullets tend to constitute the same percentage of 
the weight of the eggs from which they were hatched ? 
The data in Table III show, for each of the four groups of birds 
and for the sexes, respectively, the chick weight times one hundred 
over the egg weight or the mean percentage chick weight of egg 
weight. 
The female chicks constitute a lower mean percentage of the eggs 
from which they were hatched in all four cases. In no case, how¬ 
ever, is the difference in mean percentage significant, the differences 
with their probable errors being: 0.68 ±0.28, 0.73±0.33, 0.60±0.35, 
and 0.61 ±0.30. It would seem, then, that in the case of neither 
