170 Life and Letters of Francis Galton 



Galton having dismissed both sexual and natural selection from past or 

 present influence on finger-print patterns, argues that natural selection has 

 had no monopoly in producing genera. 



"Not only is it impossible to substantiate a claim for natural selection that it is the sole 

 agent in forming genera, but it seems, from the experience of artificial selection, that it is 

 scarcely competent to do so by favouring mere varieties, in the sense in which I understand the 

 term. 



"My contention is that it acts by favouring small sports. Mere varieties from a common 

 typical centre blend freely in the offspring, and the offspring of every race whose statistical 

 characters are constant, necessarily tend, as I have often shown, to revert to their common 

 typical centre*. Sports do not blend freely ; they are fresh typical centres or sub-species, which 

 suddenly arise, we do not yet know precisely through what uncommon concurrences of circum- 

 stance, and which observations show to be strongly transmissible by inheritance. 



"A mere variety can never afford a sticking point in the forward course of evolution, but 

 each uew sport implies a new condition of internal equilibrium, and does afford one. A change 

 of type is effected, as I conceive, by a succession of sports or small changes of typical centre, 

 each being in its turn favoured and established by natural selection to the exclusion of its 

 competitors. The distinction between a mere variety and a sport is real and fundamental. I 

 argued this in a recent work [see our discussion pp. 58-62 above of Galton's Natural Inheritance, 

 1889], but had then to draw my illustrations from non-physiological experiences. I could not at 

 that time find an appropriate physiological one. The want is now excellently supplied by observa- 

 tions of the patterns made by the papillary ridges on the thumbs and fingers." (pp. 22-3.) 



While I am very loath to say that -Galton is in error, I think that he has 

 far from demonstrated the correctness of his views. I have cited his paper at 

 considerable length because I want to indicate how keen a "mutationist" he 

 was. We can claim that he was the first to assert a distinction between 

 "mutations" (sports in his terminology) and " fluctuating variations " (varieties 

 round a typical centre, as he would call them). If the Biometric School has 

 been unable to follow him whole-heartedly in this path, it is because in his 

 case the conclusion was only in a very minor degree based on observation ; in 

 the main it flowed from a misinterpretation of his own great discovery of 

 regression f. 



Finger-Print Indexing. In the year following the presentation of this 

 memoir Galton read a second paper before the Royal Society (April 30, 1891). 

 It was entitled: "Method of Indexing Finger-Marks," and was published in 

 the Roy. Soc. Proceedings, Vol. xlix, pp. 540-548. Our author points out that 

 the indexing of finger-prints is not only of importance for criminal identifi- 

 cation, but for racial and hereditary inquiries. He especially emphasises their 

 value in the latter case : 



"The patterns are usually sharp and clear and their minutiae are independent of age and 

 growth. They are necessarily trustworthy, and no reluctance is shown in permitting them to be 

 taken, which can be founded either upon personal vanity or upon an unwillingness to communi- 

 cate undesirable family peculiarities." (p. 540.) 



* [This is the old error of the misinterpretation of regression, which led Galton so often 

 and so far astray ; see our pp. 31, 48 and 83. K.P.] 



t An additional point in this memoir (p. 20) may, perhaps, be just noted. Galton compares 

 the index found from the ratio of means of two absolute variates, with the mean of all the in- 

 dices found from the individual values of the variates. He shows that the two are nearly the 

 same. We now know the proper corrective factor required to pass from one to the other. 



