An Introduction to a Biology 



numerical conclusions from ; they are introduced solely as 

 part of an argument which is intended to show how I came 

 to see that the facts summarised in the Table {vide p. 148) 

 were equally in accord with Mendelian and Galtonian theory ; 

 and their value in this respect will not be in the least impaired 

 if it ultimately turns out that the proportion in which the 

 three categories of coat and eye colour occur are " in every 

 respect discordant with " Mendelian prediction. 



That the two mice which gave no albinos in the two 

 matings referred to really are dominant is, I think, placed 

 beyond doubt by the fact that in a third mating w^th albinos 

 they have failed to produce anything but coloured mice 

 with black eyes.^ That the remaining mice are hetero- 

 zygotes is also beyond doubt, and that a quarter of the popu- 

 lation produced by breeding them together is composed of 

 albinos remains to be demonstrated. The Table on p. 148 

 therefore is in no wise a refutation of Mendelian theory ; 

 at any rate, the suggested Mendelian interpretation of the 

 facts cannot be regarded as disproved. Nevertheless, the 

 facts are no less in accord with Galtonian theory, though 

 in a different way than I at first held ; the manner in which 

 I beheved that the truth of that theory would be borne 

 out was, as I have said before, and as I wish *to emphasise 

 again, by the gradual diminution of the albino-producing 

 capacity of each hybrid of successive generations. It now 

 appears that the manner in which that theory is borne 

 out by these facts is by the gradual invasion of the " hybrid *' 

 ranks in successive generations by dominant individuals 

 bearing the external hybrid characteristics ; whether there 

 will appear among the " dominants " or even recessives a 

 compensating number of hybrids, or even whether this is 

 demanded by Mendelian theory, is a question of fact which 

 does not aifect my argument. What I want to point out 

 is that I fell into the error of believing that that which was 



^ Besides these two mice which have been tested thrice there are three 

 which have been tested twice, two bucks and a doe, with the same result. 



