690 
Journal of Agricultural Research 
Vol. XXXI, No. 7 
Table IV. — Mean weights , classified according to incubation results , of eggs laid 
by four groups of birds 
[Eggs laid by 53 Rhode Island Red hens and 30 Rhode Island Red pullets] 
Rhode Island Red 
hens 
Rhode Island Red 
pullets 
All Rhode Island 
Reds 
Num¬ 
ber 
Mean 
weight 
Num¬ 
ber 
Mean 
weight 
Num¬ 
ber 
Mean 
weight 
Set...... 
534 
76 
37 
100 
321* 
Grams 
59.82db0.13 
60.15± . 36 
59.83± . 43 
60.51± .29 
59.64db . 17 
342 
12 
13 
65 
252 
Grams 
56.32±0.15 
55.87± . 71 
57.65± . 50 
55.81± .29 
56.36=fc . 17 
876 
88 
50 
165 
573 
Grams 
58.46±0.11 
59.56± . 46 
58. 78± . 37 
58.94± . 21 
58.20dh . 14 
Infertile_ 
Died early.. 
Died late.... 
Hatched..... 
Per cent of fertile eggs hatched _ 
70.08 
76.36 
72.71 
[Eggs laid by 50 Barred Plymouth Rock hens and 113 Barred Plymouth Rock pullets] 
Barred Plymouth 
Rock hens 
Barred Plymouth 
Rock pullets 
All Plymouth 
Rocks 
Num¬ 
ber 
Mean 
weight 
Num¬ 
ber 
Mean 
weight 
Num¬ 
ber 
Mean 
weight 
Set_____ 
148 
17 
11 
8 
112 
Grams 
60.25=t0.23 
59.90± . 79 
61.50± . 66 
60.64±1.05 
60.10± . 26 
368 
45 
27 
67 
229 
Grams 
57.57dh0.15 
57.64± .39 
56.76± . 42 
57.34± .30 
57.71± . 18 
516 
62 
38 
75 
341 
Grams 
58.33dbO. 13 
58.26± .37 
58.13dh . 41 
57.69± . 32 
58. 50± . 15 
Infertile.. __ ___ 
Died early... 
Died late... 
Hatched.. 
Per cent of fertile eggs hatched _ . . _ _ 
85.49 
70.90 
75.11 
The percentage of fertile eggs that hatched were as follows: Rhode 
Island Red hens, 70.08; Rhode Island Red pullets, 76.36; all Rhode 
Island Reds, 72.71; Barred Plymouth Rock hens, 85.49; Barred 
Plymouth Rock pullets, 70.90; all Barred Plymouth Rocks, 75.11. 
It is apparent, from an examination of the mean weights of eggs 
in each group of birds and in each breed, that there is no significant 
difference between the mean weights of the eggs whose embryos died 
either early or late and the mean weights of the eggs that Hatched. 
Apparently, then, in these groups of birds, the relative size of egg 
has had no effect on hatching quality. Dunn 3 found, however, “an 
evident tendency for eggs which die during incubation to be slightly 
larger than those which hatch.” Such a situation is not evident in 
the data shown in Table IV, and in order to test the matter conclu¬ 
sively the more homogeneous lot of 1,253 eggs laid by 24 Barred 
Plymouth Rock pullets is analyzed. 
In Table V are shown the frequency distributions and the mean 
weights of the eggs set, those which were infertile, those in which the 
embryos died eany, those in which the embryos died late, and those 
which hatched. In each case the frequency distributions follow fairly 
closely a normal curve. There are no significant differences between 
the mean weights of any two groups of eggs. The mean weight in 
grams is greater in the eggs whose embryos died early, 55.51 ±0.18, 
a Dunn, L. C. the relationship between the weight and the hatching quality of egg 
Conn. Stores Agr. Exp. Sta. Bui. 109, p. 100. 1922. 
