An Introduction to a Biology 



Mendel's law does this perfectly. Nevertheless Darbishire, 

 likewise dealing with albinism in mice, though admitting 

 that certain of his results are not in disagreement with 

 Mendel's law, is inclined rather to interpret the phenomena 

 on some such hypothesis as that of Galton " (5). 



The numerals refer to the words in italics preceding 

 them. 



(1) This shows that Castle followed me in confusing Galton's 



Law with the Law of Contribution. 



(2) Here we see that Castle has started on a right track : 



he has perceived that Galton's Law in the sense in 

 which I used it, meaning the Law of Contribution, is 

 not the same as that Law in its original form. 



(3) And yet he thinks that in its original form it was in 



harmony with the phenomena of gametogenesis as 

 then interpreted, whereas it seems to me that the chief 

 characteristic of a statistical Law is that it is inde- 

 pendent of any theory of gametogenesis whatsoever. 



(4) Of course it does : because it does not attempt to. What 



he means is that the Law of Contribution attempts 

 and fails : and this is quite true. 



(5) Here again as in (2) we see light breaking in on the con- 



fusion between Galton's Law and the Law of Contri- 

 bution. Castle sees that the theory of heredity I 

 had in mind is not quite the same as Galton's : I 

 have shown (p. 180) exactly how it differs from it. 



I will now refer to a case in which the confusion between 

 Galton's Law and that of Contribution is complete. 



In 1904 I wrote :^ " / do not propose to discuss here the 

 difference {I) between Mendehan principles and the statistical 

 conception of inheritance (2), but to consider one part of 

 the hypothesis put forward by Mendel, which is at variance 

 with Galton's theory (3). I refer to the phenomenon of 

 segregation. We have seen what Mendel says. But this 

 is flatly contradicted by the Galtonian generalisation (4), 



^ Darbishire, :04&, p. 9. 

 1 88 



