Manchester Memoirs, Vol. I. (1906), No. II. 7 



that any of the children should be like any of the parents ; 

 all that is necessary is that a particular kind of parent 

 should be associated with {i.e. should produce) as often as 

 not a particular kind of child. On the opposite page is an 

 imaginary Correlation Table, in which Pearson's Law is 

 borne out, yet in which none of the children are like any 

 of the parents. 



The fact that the relation between a given generation 

 and those that precede it, is described by a series of figures 

 which in the case of Galton's Law is '5, '25, '125, "0625 etc., 

 and which in the case of Pearson's, for eye colour in man, 

 for example, is "4947, ■3166, "1879,* has led some to believe 

 that the figures mean the same thing (which, of course, 

 they do not), and has thus constituted a trap for the un- 

 wary. Castle has done good service to progress in the 

 study of heredity by falling into it.f 



I hope I have made clear what the difference 

 between the meanings of the two series is ; for to under- 

 stand this is to understand the difference between the 

 two Laws. 



This difference is sometimes expressed in the state- 

 ment that Pearson's Law is more comprehensive and less 

 biological :|: than Galton's : and inasmuch as it embraces 

 sets of facts which are not described by Galton's formula, 

 the first of these statements is true : and inasmuch as the 

 relation between successive generations which it measures 

 is the same as the relation between two series of throws 

 of dice (in which reproduction is unknown), of which 

 every throw of the second series consists of half the dice 

 lying exactly as they fell in the corresponding throw of 

 the first series, the second is true a!so. 



* Pearson, '.O'^a, p. 221. 

 t Castle, .-03, p. 224. 



JFruwirth (:05, p. 147) goes so far as to say that " das Ahnenerbengesetz 

 ist kein biologisches Gesetz, . . . ." 



