SIZE, SHAPE AND PHYSICAL CONSTITUTION OF THE EGG. I35 



fowl. The data on which it is based are the measurements of 

 all of the eggs laid by twenty-two Barred Plymouth Rock birds. 

 For thirteen of these birds records were taken on every egg 

 laid up to 'the end of the second laying year. For the remainder 

 records were taken covering the eggs of the first laying year. 

 The thirteen birds which were alive at the beginning of their 

 second adult molt were killed at that time. The more impor- 

 tant results of the investigation may be summarized as fol- 

 lows : 



I. The Individualiiy of the Eggs of the Same Bird. 



1. The individuality of a bird is expressed in each physical 

 character of her eggs. 



2. This individuality is more pronounced in respect to the 

 size than the shape of eggs and also in respect to the weight of 

 al'bumen and shell than weight of yolk. 



3. There is a tendency for the several tgg characters to be 

 related to each other in such a way that when the eggs of an 

 individual are large they are both long and broad and each of 

 the parts is large; but the hens which lay large eggs lay eggs 

 with a smaller proportion of yolk than hens which lay small 

 eggs. Also individuals may show a decided tendency to vary 

 from the flock type in quite different degrees in different 

 characters. 



4. The eggs of an individual tend to be either uniform or 

 variable in all the egg characters but certain individuals may 

 be variable in certain ^gg characters and uniform in others. 



5. An individual is in general less variable than the race in 

 respect to egg characters; but certain individuals may show a 

 variation in an tgg character w^hich is relatively as great as the 

 variation in the race. Also certain egg characters (particularly 

 yolk weight) show a decided tendency to approach the race 

 variation in several individuals. 



6. The factors which bring about the individuality in re- 

 spect to tgg characters are too complex for analysis from the 

 data at hand. 



II. Correlation of Egg Characters. 



I. Each tgg character is related to ever}- other egg char- 

 acter, but different pairs of characters show a decidedly differ- 



