THE INHERITANCE OF WING-COLOUR IN LEPIDOPTERA. V. MELANISM IN ABRAXAs GROSSULARIATA (VAR. VAIgLEYA'I'A, PORRITT). BY H. ONSLOW. (With six Text-figures and Plate XIX.) SEVEr~AL examples of melanism have already been investigated, and their inheritance described in previous papers. The chief interest of these melanic strains lay in the trot that they were all discovered in the south of England, and far fl'om any manufacturing centres. As appears to be usual, the melanic variety in each case behaved as a simple mendelian dominant. That exceedingly variable species, Abraxas cjross~dariata, possesses a black variety, known as var. varle~jata, Porritt ~, found in Hudders- field, and now established as a domesticated strain. Basing his opinion on a single family, bred by Mr L. W. Newman (see the third table), Mr Bateson 2 concluded that the black variety was not dominant, but recessive to the type form, like the melanic variety of Odontopera bidentata (The Scalloped Hazel) investigated by Bowater ~. More recently, Porritt 4 has published the results of some breeding experiments. In 1906 he obtained "a considerable brood," fl'om a mating of varleyata x varleyata, all of which proved to be like their parents. Further, in 1907 he obtained a pairing between varle~jata ~ x tlrossulariata cf, The latter was a typical wild insect, and 9 d~o~ and 5 ~ ~ resulted, all of which were like the male parent. With a view to testing this conclusively, a strain of varle~jata was procured by the author fl'om Mr L. W. Newman, and both the I~ev. G. H. I~aynor and Mr Porritt with great kindness furnished some ova. Porl~t, G. T., Ent. Mo. Mag. Vol. xLi. p, 211, 1905. " Bateson, W., Me.l~del's Principles of Heredity, 1913, p. ,14. Bowa~m', W. J., Journal of Genetics, Vol. i~i. p. 299, 1914. 4 PorrR~, G. T., Ent. Mo. Mag. Vol. xLIII, p. 12 and p. 276, 1907. 124 The Inheritance of Wing-Colour in Lepldo2tera As it was intended later to Cam,y out experiments with var. varleyat~ and the well-known pale variety, lacticolor, some individuals of the latter variety were used in certain pairings, with the result that both lacticolor and a completely new variety, with an exceedingly handsome facies, appeared among the ~, offspring. The genetics of this Val'ieby, named vat. exquisita, I~aynor ], will be dealt with in a future communi- cation. Owing to the occurrence of these varieties, the material in the following tables has been classified into melanic and non-melanic, in order to reduce the nmnber of colmnns. The result of mating varleyata with non-melanic, that is to say, ordinary wild insects or lacticolor, was as follows : Mela~ic x IVon-mela~,ic. RR x DD. hnaginas/el Melanic Non-melantc Family Female X ]VIale ]kIale FemMe Totals ~Iale Female Totals '16 Z type x varlegata -- -- -- 6 9 15 '18 A wtrleyata, x lacticolo~ .... 1 -- 1 '18 B lacticolor x varleyata -- -- -- 19 17 36 '18K varlegata x type -- -- -- 1 -- 1 '18 L ,, x lacticolo~ ...... 3 3 '18 N x -- -- -- 1 2 3 '18 0 type x varlepata e -- -- -- 10 10 20 '18 U ,, x ,, -- -- -- 8 17 25 '19 K w~rleyata x lacticolor ..... 3 2 5 '19 IV x -- -- -- 5 9 14 '19 Z type x 'vavleyata ..... 23 20 43 '19 X w~,leyata x lacticolo~ ..... 2 -- 2 '19~ ,, x ,, -- -- -- 5 5 10 Total ...... 178 Ib is seen that the black variety is recessive both to type and to lacticolor. The amount of the black pattern in//'1 individuals appears to vary very considerably, but this point will be dealt with later. Whether lacticolor is heterozygous for vo,r~eyata or not, the variation in the amount of black is usually scarcely noticeable. 1 ~aynor, G. H., .Ent. Bee. Vol. xxI. No. 11, p. 205, November 1919. It is possible that the variety named albowvrleyala by Porritt (Ent. 1Tee. u xxIx. p. 136, 1917) is exqaisita, but in answer to some inquiries Mr Porritt says that this form was bred from stock which never contained a single specimen of lacticolor; in fact, he llad never bred the latter variety. Moreover, Mthough the resemblance is close, there appeared to be some slight but significant difference in the appearance of the black shoulder.knot ou the under surface. '~ This varleyata c~ was radiated (see p. 136). ~-I. ONSLOW 125 The result of mating v~trleya, ta, x vc~r&yata, was as tbllows : Mdccnic • Mbla,~,'ic. I,),R • RR. IlllagilleS h[ehulic Non-nlehufic Fanlily :Bred by h~ale Felnale ']'otals hlale Felnale Totals 1906 Mr G. T. Porrir~t ? ? 28 .... 'lSf~ Ova from Mr G.T. PorritL 2 1 3 -- -- -- '18 Z* Ova from Rev. G. H. ltaynor 8 5 13 -- 1 1 '19 ~' H. 0. 1 -- 1 -- -- -- '19 L H.O. 5 3 8 -- -- -- '19 0 H.O. -- 1 1 - -- -- '19P H.O. 1 -- 1 -- -- -- '20 ~ H.O. 9 3 12 -- -- -- '20 G H.O. 6 3 9 -- -- -- '20 0 H. 0. 7 3 10 -- -- -- '20 S H.O. 8 6 14 .... '20 IV H. 0. 3 2 5 -- -- -- Toi, als ...... 105 ...... 1 ~* These families contain one or more ov c~ which are radiated (see table on p. 135). It is clear that the recessive form breeds true, although the numbers are not large, owing to disease which was particularly severe in 1919. The fact that a single specimen of gross~dariata appeared in family F~, heterozygousfor varleyaga, inter se. hnagines 1,"2 r --., Zfehulic Non-nlelanic P Family Bred by Male Female Totals Male Female Totals -- Mr L. W. Newman 4 3 7 ? ? 24 '17 A ~ Ova h'om Rev. G. H. l:~aynor 1 1 2 2 1 3 '17 Y H. 0. 2 3 5 5 3 8 1.17 Rev; G. H. Raynor 7 2 9 14 6 20 2.17 ,, 11 8 19 23 25 48 3.17 ,, 13 2 15 22 26 48 4.17 ,, 1 2 3 13 2 15 7.17 ,, 4 5 9 20 12 32 8.17 ,, 5 2 7 13 10 23 9.17 ,, 2 7 9 8 16 24 12.17 ,, 1 1 2 5 7 12 13.17 ,, 1 -- 1 14 11 25 21.17 ,, 2 2 4 7 6 13 22.17 ,, 1 -- 1 2 1 3 32.17 2 -- 2 12 5 17 '18 H H.O. -- '18 T ~ H.O. 4 2 6 9 11 20 '19 N H.O. 1 '19 V ~ H.O. 4 -- 4 8 9 17 Totals ...... 107 (23 %) 352 (77 ~ Expectation ... 115 34,t, * These families contain one o1' more 3 d ~ which are radiated (see table on p. 135). 126 The bzheritanee of Wing-Colour in Lepidoptera 98 1 cmmo~ be of rely significance, as lhe ow~ mig'hl very easily have been conliamina~ed beibre lhey were received. [By ma~ing logelAmr lhe 1~ he~erozygo~es, an Fo generalion is pro- duced, which consisls approximalely of one varleyata ~o lln'ee or,hers, eilher gross,dariatt~ or hwticolor. I am very much in(lebled Io Mr R~ffnor tbr t,lle dala of his 1917 families, wlfieh are included in ~he above ~able. They supplemenl, ~he o~her figures, and ~he ~o~als are *%irly close ~o ~he e• rat;io of 3:1. All ~he parents are g'rossulariat~L bu~ sevend of ~hem are dark, and t,he oz pm'en~ of 1.17 and ~he g paren~ of 22.17 approach vat. hn,zeleigh- ensis. Since ~he pm'en~s are in a number of cases he~erozygous for h~cticolor, lifts variely occurs among lhe non-melanies in several families. Tim resul~ of maling vm'leyata Io F, helerozygo~es shows an -almost equal number of melanie and non-mebmic, as follows : Varleyata x Y~. RR, x .DI~. Imagines r-- ............ J' -, ~Ie}ILlllI ~xroll-lleIlllll Family Fenlale X MTtfle ~Iale Fcmt~le Totals 15Iale Female Tot, Ms '18 G ~ lacticolor • varleyata 15 13 28 13 14 27 '18 M * type • I 2 3 I 2 3 '18 P~ x 12 2 14 12 7 19 '18 R~ varle!lata x type 5 8 13 6 8 14 '19 A* type x varleyata 7 7 14 8 4 12 '19 B ~ hwticolor x type 14 10 24 12 8 20 '19C ~ ,, x ,, 7 2 9 6 4 10 '19 I~ ~ va'rle'!lata x ,, 9 3 12 5 1 6 '19 G ,, x ,, 2 -- 2 1 -- 1 '19 H x -- I I 2 -- 2 '19 J lacticolor x varleyata 1 1 2 2 1 3 '19 M varleyata x type 4 4 8 5 3 8 '19 Q~ x 8 6 14 12 11 23 '19/t lacticolor x wtrleyata -- 1 1 -- -- -- 't9S ~ x 11 7 18 11 8 19 '19 X ~ type x varlega,~a 4 5 9 2 4 6 '19 Y varleyata x lacticolor 3 2 5 2 2 4 '19 a type xvarleyata 2 5 7 3 6 9 '19fl ,, x ,, 3 1 4 -- 5 5 '19~ x -- 2 2 1 1 2 '19 ~" wzrleyata x type 1 4 5 2 1 3 '19 ~ x 10 9 19 17 9 26 '19 0 lacticolor x w~rleyata -- 1 1 -- -- -- '19 x ,, x ,, -- 2 2 i 3 4 '19 X ,, x ,, ..... 1 1 '19 p l,ype x 1 -- 1 -- 2 2 '19 w w~rle!/ata x type .... 1 1 '20 I exquisita x lacticolor 6 4 10 2 4 6 '20 J lactlcolor x exquisita 2 1 3 2 2 4 '20 L type x wvrleyata 8 1 9 8 1 9 '20M exquisita • type 16 9 25 9 6 15 '20 N varleyata • lacticolor 9 2 11 ,1 3 7 '20P ,, • ,, 3 1 4 2 -- 2 Totals .., 164 .116 280(51% ) 151 122 273(49~ Expectatiol~ ..