SIZE, SHAPE AND PHYSICAL CONSTITUTION OF THE EGG. 109 
4. The egg is more variable in length than in breadth. In a 
few individuals the difference between the variation in these 
characters is not significant. 
'The following list arranges the egg characters in the order 
of their variability. 
j Egg weight. 
| Yolk weight. 
( Albumen weight. 
| Shell weight. 
Length. 
Breadth. 
It is especially worthy of note than the variation coefficients 
for yolk and shell are much higher than for the whole egg, 
and the coefficient for albumen is at least as high. There 
must then be a compensatory variation among the parts. The 
data show also that the eggs of the breeding season have dis- 
proportionately large yolks and a consequent smaller percentage 
of albumen than the eggs at other seasons. 
The eggs of each individual (as well as the means of the 
different individuals) vary less in respect to the dimensional 
characters than in respect to weight. The eggs must vary 
simultaneously in both dimensions. 
Whereas a comparison of the means for the different individ- 
uals shows that intra-racially the eggs are more uniform in 
yolk weight than in the weight of the other parts or of the 
whole egg, within the eggs of the individual the yolk weight is 
almost as variable as the shell weight and much more variable 
than the weight of the albumen or of the whole egg. 
THE RELATION OE EGG CHARACTERS TO OTHER CHARACTERS. 
The factors which bring about the individuality in the eggs 
of the different birds are too complex for analysis from the 
data in hand. Other facts known about the birds were investi- 
gated to discover possible relationships between the variation 
in egg characters and variation in other characters. The re- 
sults were as follows : 
1. The early hatched birds laid earlier in the fall than those 
hatched during the middle of the season, while the late hatched 
birds did not lay until spring. 
