114 MAINE AGRICULTURAL EXPERIMENT STATION. I914. 



seasonal fluctuations which will be discussed later; but with 

 very few exceptions the eggs of the second year are decidedly 

 larger than the eggs of the corresponding months of the first 

 year. That is the eggs of a bird continue to increase in weight 

 with the increased maturity of the bird at least up to the end 

 of the second laying year. After the beginning of the first 

 breeding season the increase in weight is much slower than dur- 

 ing the few months which precede. 



The weight of the egg is made up of the weight of the three 

 parts albumen, yolk and shell. Each of these parts are alsO 

 variable in weight. In fact, each is more variable than the 

 weight of the whole egg. 



A study of the progressive change in each of these parts can 

 be made in a manner similar to the above study of egg weight. 



The monthly mean yolk weights show ever more uniformily 

 than the weight of the whole egg that the weight increases 

 rapidly to the beginning of the first breeding season and from 

 that time on more slowly. The yolk weight shows the seasonal 

 fluctuations shown by the egg weight; but 'their magnitude is 

 smaller. 



The monthly mean albumen weights show a less abrupt rise 

 during the first three months and greater seasonal fluctuations 

 than the monthly mean egg weights or yolk weights. In gen- 

 eral, however, they show an increase in albumen weight with an 

 increase in the age of the bird. 



The monthly mean shell weights are larger for the second 

 than for the first year but they show a large proportional varia- 

 tion which is usually related to the variation shown by the 

 other parts but may be independent and in the opposite direc- 

 tion. For example during the first three months laying all but 

 one of the birds show a decrease in shell weight which is as 

 decided as the increase in the weight of the other two parts. 



In order to generalize the study of the increase in the weight 

 of eggs and of each of its parts as the bird grows older it is 

 desirable to bring together the results of tht; study on the 

 individual birds. 



The birds used in this investigation form a more homoge- 

 neous group than is often available for statistical work. They 

 were "pure-bred" in the fancier's sense and line-bred and were 

 within a few weeks of the same age. They had lived under the 



