An Introduction to a Biology 



logical 1 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 rela- 

 tion 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 also. 



§3 

 (a) The Law of Diminishing Individual Contribution 



In my paper on the supposed antagonism of biometric 

 to Mendelian theories of heredity, I showed that a set of 

 facts (summarised in the Table, vide p. 148 swpra), appear- 

 ing at first to be a complete refutation of Mendel's Law, 

 could easily be shown to be equally in accord with both 

 Mendelian and Galtouian theories. ^ Mendel's Law describes 

 the individual phenomena in this case perfectly : Galton's 

 Law describes the mass result composed of these very indi- 

 viduals mating at random perfectly. The latter describes the 

 proportions, the former accounts for them. The Galtonian 

 deals with individuals from the point of view from which 

 the physicist deals with atoms ; the MendeHan deals with 

 them from that of Clerk Maxwell's demon. 



Now just at the same time that I announced my discovery 

 that the proportions of the albinos in this case were not 

 evidence against the truth of Mendel's Law,^ Castle made 

 the same discovery.* But he argued from his discovery^ 

 not (as I did) that the two theories were compatible but 

 that Galton's was wrong ; that is to say, he must have 

 thought that the two theories were mutually exclusive ; 

 which indeed he did : but not in the same way that I did. 



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

 ist kein biologisches Gesetz. ..." 

 2 Parbjshire, :05a, p. G, ^ iTjid., :05a, p. 9. * Castle, :05, p. 17 et seq. 



