A Cooperative Studji 
335 
We are thus again faced with the fact that the cross-hnmotyposis of the eggs 
of 1914 is substantially higher than that of 1913. We still see the markedly 
emphasised individuality of the female birds. 
We have next to enquire whether, the organic relations being practically 
constant, the cross-homotyposis has increased in proportion or not to the direct 
homotyposis. We can test this by Pearson's suggested relationship*, namely 
Cross-Homotypic Correlation of x and ;j = \ {correlation of x with x + correlation 
of y with y] x {the organic correlation of .» with y]. The following table gives the 
calculated and observed cross-homotypic correlations for the seasons 1913 and 
1914. 
TABLE XXII. 
Cross-Homotypic Correlations as Calculated and Observed. 
Character Pair of two Egg.s 
Season 1913 
Season 1914 
Calculated 
Observed 
Calculated 
Observed 
Length and Breadth... 
Longitudinal and Transverse Girths 
Length and Longitudinal Girth 
Breadth and Longitudinal Girth ... 
•1090 
•2568 
•4278 
•2674 
•0922 
•2603 
•4229 
•2530 
•1408 
•3638 
•5426 
•3392 
•2621 
•4546 
•5854 
•4162 
Thus while the calculated values were in excellent accordance with the ob- 
served in 1913, they are very inadequate to express the increased individuality in 
1914. In other words the cross-homotyposis appears increased even at a greater 
rate than the direct homotyposis which we have shown in itself to be markedly 
emphasised. 
What we are accordingly confronted with in the season 1914 is an exuberance 
of individuality and the possibilities which such a variation of individuality 
suggests. It may be confined to the externals of the egg, but the physiological 
factors which determine those externals must at least be in close proximity and 
may, perhaps, be affiliated with others which affect matters tnuch more important. 
The approximate constancy of type, variability and (organic correlation for these 
two seasons coupled with the marked change in homotyposis is a problem which 
demands further observations and much hard thinking. 
* Phil. Trans. Vol. 197 A, p. 290. 
