CHAPTER IV 
BIOMETRY 
In the present chapter we have to consider in some 
detail the manner in which purely statistical methods 
have been applied to certain biological data; a proceed- 
ing to which the term biometry has been attached 
by Professor Karl Pearson. Before concluding our 
account we shall give a brief sketch of some of the 
more important evidence bearing upon the problems 
of evolution which has been brought to light by the 
methods of biometrical science. 
The first investigator to apply the methods of 
statistics to the solution of biological problems was the 
Belgian astronomer, Quetelet. In 1845, in the form 
of a series of letters addressed to the Grand Duke of 
Saxe-Coburg and Gotha, Quetelet published an admir- 
able account of the theory of probability and its 
relation to human affairs, and one in which the use of 
advanced mathematics was avoided. The pioneer of 
biometry in this country is Francis Galton, whose book 
on ‘Natural Inheritance’ embodies an extremely 
lucid introduction to the statistical study of variation 
and inheritance. From these two works are derived 
most of the ideas submitted in the present chapter. 
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