133 



On the Cross-breeding of Two Races of the Moth Acidalia 



virgularia. 



By Louis B. Prout, F.E.S., and A. Bacot, F.E.S. 



* 



(Communicated by Leonard Hill, F.E.S. Eeceived January 8, — Read 

 February 25, 1909.) 



A. Introduction. 



The general interest which has been aroused of recent years by the various 

 researches which have been undertaken in investigation of the working of 

 Mendel's Law of Heredity, and the adaptability of the Order Lepidoptera to 

 such investigation, have led us not only to reconsider the results of some 

 earlier and undirected experiments in moth-breeding, but also to seek out 

 some peculiarly suitable species in order to take in hand a more exhaustive 

 course of study along the lines most likely to yield further results in eluci- 

 dation of Mendelism. 



Be'sumi of some Previous Bearing Experiments. 



Perhaps a brief reference should be made to our previously recorded 

 attempts at pedigree-breeding. 



Lasiocampa quercus. — Crossings of the various local races were carried out 

 extensively by A. Bacot and J. C. Warburg in 1896-1900, and the results 

 of their work detailed in ' The Entomologist's Record,' vol. 13, pp. 114-116, 

 237-240, 256-259, 313-317, 338-342. The outstanding feature, as regards 

 a possible bearing on Mendelism, is that two races from the same 

 geographical region, when hybridised, produced progeny that segregated 

 into the two parent forms, whereas when the southern French var. 

 meridionalis, Tutt, was crossed with the Scottish var. callunce, Palmer, no such 

 segregation occurred, the larva? being of an intermediate type. 



Forres — Triphcena comes (Agrotis comes, Stgr. Cat.). — Some rather 

 unsystematic breeding experiments with the interesting Forres forms of this 

 species were made in 1902-1903 by ourselves and others, and are recorded 

 in ' The Entomologist's Record,' vol. 15, pp. 217-221 ; vol. 16, pp. 1-5. 

 The progeny from two wild meianic females segregated, that from ? A 

 being divisible into 74 typical and 93 meianic, that from ? B into 39 typical 

 and 22 meianic. From brood A offspring was obtained, namely, a batch 

 from a single meianic pairing and a batch from meianic " stock " ; the former 

 gave 25 typical and 52 meianic, the latter 20 typical* and 48 meianic ; 



* " Nine" in ' Ent. Eec.,' vol. 16, p. 3, line 19, is a laps. col. or misprint for " seven." — 

 L. B. P. 



