458 



GENETICS 



ural conditions, analyzing these data by mathematical or statis- 

 tical methods, and formulating generalizations concerning heredity 

 and variation that will be true for the whole group but for no 

 particular individual. Sir Francis Galton (1822-1911) did the 

 first serious work of biometrical character, although Quetelet 

 (1794-1874) had foreseen the value of such a method of attack. 



Fig. 238. — Diagram illustrating Galton's law of Ancestral Inheritance. The 



large square represents the total of any individual's inheritance. The smaller 



areas indicate in what proportions the total is derived from the ancestors. 



Galton studied the relation between height of parents and height 

 of offspring in over a thousand cases in man. From these data he 

 proposed his laws of " Ancestral Inheritance " and " Filial Regres- 

 sion." According to the law of Ancestral Inheritance, the parents 

 of any individual contribute one-half of his inheritance while the 

 grandparents contribute one-fourth, the great-grandparents, one- 

 eighth, the great-great-grandparents, one-sixteenth, etc. (Fig. 

 238.) The individual is, therefore, like its parents, but varies 



