332 SCIENCE PROGRESS 



characters, whilst those which are common to all the individuals 

 of a race should be called " racial." 



Do we know anything of the behaviour of racial characters 

 when crossed ? There are a great many illustrations from 

 which I will select only a few. The cross between negro and 

 Caucasian is a good example, and I take it the more willingly 

 because Prof. Davenport, who as I have already pointed out 

 apparently believes that all characters are transmitted alterna- 

 tively, has used it. I am enabled to go further than this and 

 use his statement of the case because of the very frank and fair 

 manner in which he has dealt with the facts. He shows that the 

 individuals forming consecutive generations may vary from as 

 light as Caucasians to 46 per cent, of black in the skin. He goes 

 on to say: "Just as perfect white skin colour can be extracted 

 from the hybrid, so may other Caucasian physical and mental 

 qualities be extracted and a typical Caucasian arise out of the 

 mixture. However, this result will occur only in the third or 

 later hybrid generation, and the event will not be very common." 

 I suppose that we may presume that fresh white blood is being 

 brought in at each generation and that even when- several 

 individuals who appear to be pure white have been produced, 

 negro characters will be liable to appear in their offspring. The 

 final production of a pure white race could therefore be more 

 easily explained by a process of swamping than by alternative 

 inheritance. 



A better example, because it affords a direct comparison of 

 the behaviour after crossing between similar characters, one of 

 which is racial and the other individual, is afforded by the 

 breeding experiments of Messrs. Prout and Bacot. 1 They found 

 that the moth Acidalia virgularia in the neighbourhood of 

 London was dark. The same moth found at Hyeres in the 

 South of France was white. They crossed individuals from the 

 two races and bred ten generations which provided between five 

 and six thousand specimens. There was no segregation into 

 dark and white groups, but such delicate intergrading between 

 the two parent forms that grouping was impracticable. In the 

 case of local variants of other Lepidoptera, e.g. Tryphoena comes 

 and its dark aberration, Xanthorhoe ferrugata and its black 



1 " On the Cross-breeding of the Moth Acidalia virgularia? Proc. Roy. Soc. 

 B, vol. lxxxi. 1909. 



