oct. i, 1925 Relation of Shape and Size of Eggs to Hatching Quality 687 
embryos which died up to and including the fifteenth day of incu¬ 
bation, while those recorded as having died late are the embryos 
which died after the fifteenth day of incubation. 
SHAPE OF EGGS IN RELATION TO HATCHING QUALITY 
The evidence on the relationship of egg weight and hatching quality 
is presented in Tables I, II, and III. In Table I the incubation 
results of the 1,253 eggs laid by the 24 Barred Plymouth Rock pullets 
are given, showing for each shape-index class the number of eggs set, 
the number of infertile eggs, the number which died early, the number 
which died late, and the number which hatched. 
i 
Table I. — Incubation results of eggs for different classes of shape index 
[Eggs laid by 24 Barred Plymouth Rock pullets] 
Shape index 
Number set 
Infertile 
Died early 
Died late 
Hatched 
61.00 to 62.99 . . _ 
2 
2 
63.00 to 64.99. 
3 
1 
1 
. 1 
65.00 to 66.99 __ . 
13 
2 
6 
5 
67.00 to 68.99. 
33 
1 
3 
10 
19 
69.00 to 70.99__ 
89 
4 
6 
21 
58 
71.00 to 72.99.. 
172 
11 
14 
43 
104 
73.00 to 74.99__ 
279 
28 
31 
61 
159 
75.00 to 76.99__ 
295 
35 
32 
54 
174 
77.00 to 78.99... 
235 
26 
23 
42 
144 
79.00 to 80.99.x._ 
85 
7 
5 
19 
54 
81.00 to 82.99... 
35 
1 
3 
15 
16 
83.00 to 84.99__ 
12 
1 
2 
2 
7 
Total__ 
1,253 
115 
121 
274 
743 
Mean shape index___ 
75.07±0.07 
75.54±0.18 
75.14±0.20 
74.89±0.15 
75.05±0.08 
Standard deviation. 
3.42db ,05 
2.92± . 13 
3.26± .14 
3.69± . 11 
3.40db .06 
Coefficient of variability... 
4.56± . 06 
3.87± .17 
4.34± .19 
4.93± .14 
4.53± .08 
Of the 1,253 eggsjset, 1,138 (90.82 per cent) were fertile, and 743 
(59.29 per cent) hatched. Of the fertile eggs, 121 (10.63 per cent) 
died early, 274 (24.08 per cent) died late; and 743 (65.29 per cent) 
hatched. 
The mean shape index for the different groups of eggs was as 
follows: Number set, 75.07±0.07; infertile, 75.54±0.18; died early, 
75.14 ±0.20; died late, 74.89 ±0.15; hatched, 75.05 ±0.08. The 
differences in mean shape index are very slight and are not significant; 
as, for instance, the difference with its probable error between the 
mean shape index of the highest value, 75.54 ±0.18, and the mean 
shape index of lowest value, 74.89 ±0.15, is 0.65 ±0.23. The relative 
and absolute amounts of variation in shape index, as shown by the 
standard deviations and the coefficients of variability, are somewhat 
similar. Judging from the results as shown in Table I it would seem 
that the shape of an egg does not affect its hatchability. 
The percentage of fertile eggs that hatched for each shape-index 
class in Table I is not shown, however, since the number of eggs set 
in some of the shape-index classes was very small and comparisons 
of hatchability between any two classes would not provide a satis¬ 
factory basis of determining the possible influence of shape of egg 
on hatchability. For instance, in the shape-index class 61.00 to 62.99 
