330 X)n the Xest and Eggs of the Coninion Tern 
This is a significant and fairly substantial correlation between colour and 
colour value. 
It would appear as if absence of Sorby's oozhodeine pigment* also involved 
less copious pigment material in general. 
(iv) Organic Relations in Shape and Size. 
The fundamental tables are Tables G to L at the end of the paper. The 
correlations are as follows : 
TABLE XVII. 
Organic Correlations in two Seasons. 
Character Pair 
Symbols 
Correlation, 1914 
(c. 1110) 
Correlation, 1913 
(c. 294) 
Length and Breadth 
Longitudinal and Equatorial Girths 
Length and Longitudinal Girth 
Breadth and Longitudinal Girth ... 
Index and Length ... 
Index and Breadth ... 
Index and Longitudinal Girth 
L,B 
O'l, 0',, 
L, G, 
B, G, 
IL 
I B 
I, G, 
•2104+ -0193 
•5139+^0149 
•8515+^0055 
•4840+ ^0155 
~ •7577 + ^0086 
•4537 + ^0161 
- ^4496 + •Oiei 
•2220+ ^0374 
•5297+ -0284 
•8804+ ^0088 
•5216+ ^0286 
- •7284+^0185 
•5033+^0294 
- ^3832 + •0336 
The following table contains the seasonal difference and its probable error. 
TABLE XVIII. 
Seasonal Change in Correlation. 
Character Pair 
A= 1914—1913 
Probable error of A 
L and B 
- •0116 
+ ^0421 
Gi and G,, 
- ^0158 
+ ^0321 
L and G; 
- ^0289 
+ -0104 
B and Gi 
- •0376 
+ ^0325 
1 and L 
- ^0293 
+ •0-204 
I and B 
- ^0496 
+ -0335 
1 and Gi 
- -0664 
+ •0373 
With the exception of the correlation of Length and Longitudinal Girth none 
of these differences has a significant relation to their probable errors. In the case 
mentioned, however, such a deviation would occur in excess 3 times in 100 trials 
and in defect 3 times in 100 trials, or as we have made 7 trials the odds against it are 
only 52 to 48. We cannot therefore lay much stress on it, and conclude that no 
seasonal change in the organic correlations is to be observed between 1913 and 1914. 
As there were considerable changes in the means (see our p. 310) this result confirms 
* " On the Colouring-matters of the Shells of Birds' Eggs," Zoological Society's Proceedings, 1875, 
p. 359. 
