8 Darbishire, Laws of Heredity. 



3 id). The Law of DiminisJiing Individual Contribution. 



In my paper on the supposed antagonism of biometric 

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

 facts (summarized in the Table on page 6 of that essay), 

 appearing at first to be a complete refutation of Mendel's 

 Law, could easily be shown to be equally in accord with 

 both Mendelian and Galtonian theories.* Mendel's Law 

 describes the individual phenomena in this Q3.se perfectly : 

 Galton's Law describes the mass result composed of these 

 very individuals 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 

 Mendelian 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,"f- 

 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. For whilst the way in which I made that 

 error was by lifting Mendel's Law from the level of a 

 would-be explanatory to that of a purely descriptive 

 Law, he made it by lowering Galton's from the level of 

 a purely descriptive to that of a would-be explanatory 

 one. And the reason that I discovered my mistake 

 before he did was that it is easier to see that Mendel's 

 Law is something more than a purely descriptive one, than 

 it is to see that Galton's is not a would-be explanatory 



* Darbishire, :05a, p. 6. 

 t Darbishire :05a, p. 9- + Castle :05, p. 17 £/ seq 



