ioo SCIENCE PROGRESS 



which have already been published, 1 since the results in that 

 case happen to be simpler than in some other instances which 

 have been worked out. 



In the common currant moth (Abraxas grossulariata) there is 

 a rare and very distinct variety (" lacticolor") found in the wild 

 state almost exclusively in the female. Crossing-experiments 

 were made between this variety and the type-form ; the results 

 were as follows : 



(i) Lacticolor ? x type S gave type S, type ?. 



(2) Heteroz3'gous (crossed) type ? x heterozygous type male 



gave type 6*, type ?, lacticolor ?. 



("type c?, lacticolor S. 



(3) Lacticolor ? x heterozygous type <? gave| type ?> lacticolor <t m 



(4) Heterozygous type ? x lacticolor S gave type c?, lacticolor ?. 



(5) Lacticolor ? x lacticolor S gave lacticolor <$ and ? . 



(6) Wild type ? x lacticolor <$ gave type <$, lacticolor ?. 



These results at first may seem hopelessly confusing but 

 there are several points of interest about them. Firstly, the 

 lacticolor character behaves as a Mendelian recessive, dis- 

 appearing in the-first cross (No. 1) and reappearing after mating 

 (2). Secondly, starting with a lacticolor female, it is possible to 

 get males of that variety only in one way, viz. by pairing such 

 a female with a heterozygous male, i.e. a male which is typical 

 in appearance, but being of lacticolor parentage bears the re- 

 cessive lacticolor character. Lacticolor males are also produced 

 from mating lacticolor males and females together (No. 5); but 

 from any other form of union all the lacticolor individuals which 

 emerge are females. A third point of great importance is that 

 converse crosses do not give similar results, the most un- 

 expected case of this appearing in matings of types No. 1 and 

 No. 6. In the first, a lacticolor female paired with a wild (pure) 

 type male gives all the offspring of both sexes perfectly typical, 

 a quite normal Mendelian result, since lacticolor is recessive to 

 the type. But if a pure, wild female is mated with a lacticolor 

 male, the male offspring are typical but the female are al! 

 lacticolor — exactly the same result in fact as when a first-cross 

 female is used instead of a wild one. 



1 Doncaster and Raynor, Proc. Zoo. Soc. 1906, i. p. 125 ; and Doncastei\, 

 Reports to Roy. Soc. Evolution Committee, iv. 1908, p. 53. 



