Correlation and Application of Statistics to Problems of Heredity 79 



the case of recording disease. Much of this the reader who wishes to go 

 farther than our pages will find more easily here than in the original papers. 

 Certain numerical misprints in the tables require that they should be care- 

 fully examined before use. 



J. Discontinuity in Evolution. In 1894 appeared William Bateson's 

 Materials for the Study of Variation, treated with especial regard to Dis- 

 continuity in the Origin of Species. \One ofothe strange misconceptions with 

 regard to Galton's views and to his work lies in the fact jthat- h e ha s been ovei T 

 andr-over again considered as the propounder of the view that evolutionJias_ 

 takfinj)lace hy iJie_selection of slight or- continuous vajiatians^ _ As~amatter 

 of fact Galton had for some years before t.hfl_aj>pgg.ra.r)cft of Pnit^sonVliook— 

 been preaching emph^aticany^Jlie^dpctnne of djscontinuity-i&r evolution. S 

 Indeed his opinions on th e manne r_oXj3 y7nuEioTr ~date back to 1872 : see our 

 Vol. II, pp. 84, 170-174 and 190. They are more clearly "expressecTnTtKe 

 preface to the 1892 reprint of Hereditary Genius. There we read : 



"Another topic would have been treated more at length if this book were rewritten — 

 namely the distinction between variations and sports. It would even require a remodelling of 

 much of the existing matter. The views I have been brought to entertain since it was written, are 

 amplifications of those which are already put forward in pp. 354-5*, but insufficiently pushed 

 there to their logical conclusion. They are that the word variation is used indiscriminately 

 to express two fundamentally distinct conceptions: sports and variations properly so called. 

 It has been shown in Natural Inheritance that the distribution of faculties in a population 

 cannot possibly remain constant if on the average the children resemble their parents. If they • 

 do so the giants (in any mental or physical particular) would become more gigantic and the 

 dwarfs more dwarfish, in each successive generation. The counteracting tendency is what I 

 called 'regression.' The filial centre is not the same as the parental centre but it is nearer to 

 mediocrity ; it regresses towards the racial centre. In other words the filial centre (or the 

 fraternal if we change the point of view) is always nearer, on the average, to the racial centre 

 than the parental centre was. There must be an average ' regression ' in passing from the 

 parental to the filial centre." (pp. xvii-xviii.) 



The flaw in Galton's argument is again one that we have had several times 

 to notice, namely that he is overlooking the fact that he has clubbed together 

 parents of all possible types of ancestry, and the " regression" of his sons is 

 solely due to the large number of such parents who have sprung from an 

 ancestry mediocre or below mediocrity. The amount of filial regression depends 

 entirely on the amount of this mediocrity, and there will be no regression 

 if two or three generations above the parents are of like deviation from 

 mediocrity. Thus although it may still be a matter for experiment and dis- 

 cussion, whether evolution proceeds by variations proper or by sports, whether 

 it be continuous or advance by jerks, the reason which made Galton the pioneer 

 in advocating discontinuous evolution was a misinterpretation of his own 

 discovery of " regression." -f 



* These pages deal with Galton's idea of the stability of types : see our p. 61 and Vol. II, p. 1 1 3. 

 It is quite reasonable to suppose that by successive selection of extreme variations proper we 

 might reach a position of unstable equilibrium of the parts of an organism. But there does not 

 exist experimental evidence at present to indicate that such instability would lead to a sport 

 breeding truly rather than to non-viable forms of the organism. See our pp. 93-4. 



