ON THE STATISTICAL VIEW OF NATURE. 621 



Mr Galton found ready, or instituted himself, vari- 

 ous countings of large numbers, which formed valuable 

 material for his mathematical schemes, and which 

 confirmed them in a surprising degree. .. Some very 

 elaborate series of measurements of the varying dimen- 

 sions of individual members in large crowds of animals 

 were published by Prof. Weldon, whose monograph on 

 Crabs will always remain an historical document. 1 It 

 was noticed about the same time that the attempt to 

 bring the measured deviations from the average into 

 a symmetrical arrangement on the sides of more or 

 less was impossible, and the fact had to be realised 

 and mathematically expressed that special influences 

 tending towards change on the intermixing of different 

 varieties produced an asymmetrical distribution or fre- 

 quency : 2 in fact, nature works with loaded dice, pro- 

 ducing a bias in certain directions ; this is the favour 

 which, according to Darwin, Wallace, and Lamarck's 

 ideas, must meet the better fitted individuals and 

 exact from them a smaller tribute in the inevitable 

 process of destruction and removal. 



We owe it to Prof. Karl Pearson to have first grasped 

 clearly and comprehensively the mathematical problem son. The 



mathemati- 



involved, and to have solved it in a manner useful for cal P roblem 



45. 

 Prof. Pear- 



1 See the ' Proceedings of the 

 Royal Society' since 1890, notably 

 vol. Ivii., 1895, p. 360 sqq. 



2 "An asymmetrical frequency 

 curve may arise from two quite 

 distinct classes of causes. In the 

 first place the material measured 

 may be heterogeneous, and may 

 consist of a mixture of two or 

 more homogeneous materials. . . . 



The second class of frequency 

 curves arises in the case of homo- 

 geneous material when the tend- 

 ency to deviation on one side of 

 the mean is unequal to the tend- 

 ency to deviation on the other 

 side" (Karl Pearson, "On the Ma- 

 thematical Theory of Evolution," 

 ' Trans. Roy. Soc.,' 1&95, p. 344), 



