Io6 MAINE AGRICULTURAL EXPERIMENT STATION. I9I4. 
2. The eggs of an individual are more like each other than 
they are like the eggs of other individuals of the same strain. 
3. In spite of this resemlblance between the eggs of the 
individual they nevertheless show a certain degree of variation 
in all their characters. 
4. The first eggs laid by the pullets are smaller than those 
laid by the same birds later. 
An analysis of the factors underlying this individuality and 
variation in the quantitative characters of the egg offers a new 
point of attack in the study of -the physiology of egg produc- 
tion. A statistical study wasrnmde of the: quantitative charac- 
ters of all of the eggs laid by twenty-two ’Barred Plymouth 
Rock birds during theiTtfi^st two laying years.- ./These birds 
were all from the Maine Agricultural E^rpenmeni Station 
strain, the purity of which has been amply proven by breeding 
experiments. 
This paper presents briefly the results of this investigation 
of the shape and size, both absolute and relative, and the pro- 
portion of parts of the successive eggs of each of these birds. 
It includes (a) a study of the individuality of the eggs of each 
bird and the variation among them; (b) a study of the relation 
of the individuality of the eggs to other facts known about the 
bird, such as body weight, relative size of the several visceral 
organs, age, number of eggs laid, and tendency to broodiness ; 
(c) the variation in egg characters in relation to the age of the 
bird, the seasonal reproductive cycles and the intensity of the 
reproductive activity, including the grouping of the successive 
eggs into clutches and litters, the size of these groups and the 
position of the eggs within them. 
The Individuality oe the Eggs oe Each Bird in Regard to 
Shape, Size, and Size and Proportion of Parts. 
It was not necessary to resort to mathematical calculation 
to demonstrate the fact that the eggs of the different individual 
birds used in this investigation varied considerably in respect 
to size and shape. This inter-dndividual variation was easily 
seen by comparing the eggs of the different individuals. The 
eggs of one bird were from one-fourth to one-third larger than 
