CORRELATION 103 
regard to relationships from among the general 
population to which these fathers and sons belonged. 
Now we shall see later on that this is not the only 
way of looking at the phenomenon of heredity, nor is 
it the way which is most familiar to biologists. But 
62 64 66 68 70 72 74 76 
F 
72ab 
B 
74/ 
76} D 
Fic. 9.—D1AGRAM OF CORRELATION, 
it is important to remember that what the biometrician 
means by amount of inheritance is a numerical value 
which expresses the average degree of likeness between 
a particular pair of relatives—for example, fathers and 
sons. 
