45 



Further Experiments on the Cross-breeding of Two Races of the 

 Moth Acidalia virgularia. 

 By W. B. Alexander, B.A., late Vintner Exhibitioner of King's College, 

 Cambridge. 



(Communicated by Prof. E. B. Poulton, F.R.S. Beceived January 3, — Bead 

 February 22, 1912.) 



A communication on the heredity of the two forms of this species was 

 read to the Boyal Society on February 25, 1909. In that paper 

 Messrs. Prout and Bacot gave an account of a large number of broods of 

 this moth reared by them for nine generations. 



At the end of the paper they mentioned that they had handed to 

 Mr. W. Bateson ova produced by pairings in generation Fi . . It was the 

 larvse derived from these ova which Mr. Bateson gave into my charge in 

 February, 1909. 



Of the five broods which I thus obtained I only managed to continue two, 

 as the individuals of the others emerged at such long intervals that I never 

 had a male and female alive at the same time. Fortunately, however, the 

 two I reared were the most interesting. 



Brood 2. — This brood had been labelled DI$fc, gen. xi, by Mr. Bacot. 

 Eleven moths emerged (4^,7 $ ) and from them I obtained two lots of ova 

 — Broods 6 and 7. From Brood 6 I reared 35 moths (16 ^,19 ?) and 

 obtained three more lots of ova — Broods 9, 11, and 12. Brood 11 was 

 liberated in the larval stage ; from Brood 9 I reared 64 moths and from 

 Brood 12, 38 moths (23 <$ , 15 $ ). From Brood 7 I reared 30 moths 

 (14 (J, 16 $ ) and obtained one lot of ova — Brood 13 ; from which I reared 

 92 moths (45 ^,47 ? ). 



Thus of this strain I reared no less than 270 individuals, distributed in 

 six families and three generations, and the striking feature was that they 

 showed no appreciable variation. They were all of a yellowish colour with 

 a slight amount of dark speckling on the wings. 



I had not at this time seen any specimens of the original light form of the 

 species, var. canteneraria, from Hyeres, but when, through the kindness of 

 Prof. Poulton, I was enabled to examine Messrs. Prout and Bacot's specimens 

 in the Hope Collection at Oxford, I saw at once that all the descendants of 

 my Brood 2 should certainly be classed as canteneraria. They did not show 

 any more speckling of black than typical forms of that variety, but their 

 yellow ground-colour was much darker than that of typical canteneraria. 



