SIZE, SHAPE AND PHYSICAL CONSTITUTION OF THE EGG. 107 
the eggs of one of the others. Some of the birds laid eggs 
which were long and narrow/others those which were short and 
broad. The eggs of some individuals were distinctly pointed, 
while those of others were not. 
Not only was it possible to see this individuality by compai- 
ing the eggs of the different individuals laid at the same sea- 
son, but by preserving some of the shells of the eggs of each 
bird at various seasons it was possible to see that the relative 
size and the shape of the eggs of a fowl are to a large extent 
permanent characteristics of the individual. 
The present investigation deals primarily with the quantita- 
0 or measurable characters of the egg, but that the individ- 
uality of the different birds manifests itself also in certain 
qualitative characters is illustrated by a comparison of the coloi 
and markings of the eggs of the different birds. 
This variation which is seen by a comparison of the egg a 
themselves is shown equally clearly by a comparison of the 
measurements of the characters. It is not confined to the ex- 
ternally visible characters (dimensions, shape and size) but 
extends to the size and the proportion of the parts which make 
up the egg. 
A statistical analysis of the data shows the following points : 
INT^R-INDIVIDUAL VARIATION. 
1. The characteristic eggs of the different individuals show 
variation in all egg characters. 
2. They differ more in size than in shape, and they differ 
more in the amount of albumen and shell than in the size of the 
yolk. 
3. There is a general correlation between the various char- 
acters of the egg. That is, when a bird’s eggs are large they 
are both long and broad and contain a large yolk with a large 
amount of albumen and shell. The amount of yolk, however, is 
not proportionately large, so that the birds which lay large 
eggs lay eggs which have a relatively small percentage of yolk. 
4. In spite of this general relationship the eggs of one in- 
dividual may vary disproportionately in any one of the char- 
acters measured. 
5. There is an evident individuality among the birds also 
in the amount of variation in the egg characters. The uniform 
