1906.] BREEDING EXPERIMENTS WITH LEPTDOPTERA. 129 



It may be pointed out that this case is so like what is known 

 of some other instances of alternative inheritance in moths, e. g. 

 in Amjjhidasis hetularia and its var. douhledayaria, that it will 

 probably be found that these also are simple cases of Mendelian 

 inheritance. 



II. — Abraxas grossulariata. 

 (Experiments by the Rev. G. H. Raynor.) 



We now turn to the case of Abraxas grossulariata and its var. 

 lacticolor (Jiavofasciata). Mr. Raynor obtained, some years ago, 

 a rare variety of the female, in which the black markings are very 

 much reduced and assume a partially linear form. They are also 

 characterised by their indefiniteness of outline ; instead of the 

 sharp edge to the black marks which is characteristic of the type, 

 in var. lacticolor the black spots have an indefinite appearance, 

 which' makes them appear to have been put on with a nearly dry 

 brush. The only exception to this rule is the spot in the centre 

 of the fore wing, which is more conspicuous than in the type 

 (see PI. yill. figs. 4 & 5). The var. lacticolor may thei-efore be 

 regarded as resembling an albino, in which the black pigment is 

 reduced to a constant extent, but not quite absent. The yellow 

 bands do not differ from those of the type. It should be men- 

 tioned that the amount of black vai-ies very widely in the type, 

 but at its most extreme reduction the insect does not resemble 

 lacticolor, since the spots are small and definite. Among the 

 many thousand insects bred by Mr. Raynor, no intermediate 

 between lacticolor and the type has occurred. 



When the original lacticolor $ was paired with a normal S , all 

 the offspring were normal. When, however, two of the progeny 

 of such matings were paired together, some of the female offspring 

 were lacticolor, but the var. did not occur among the males 

 (Table VIII.). A number of such families were reared which are 

 not included in the tables, since the numbers were at first not 

 recorded. It appeared, however, that the var. lacticolor is a 

 Mendelian recessive of quite a new type, since it was known only 

 in the female, and more exiict experiments were undertaken to 

 investigate it further. 



In 1903, in addition to pairings of the type DR x DR (first 

 crosses paired together), lacticolor 2 s were paired with hetero- 

 zygous Ss (see Table IX.). The result of these matings was 

 that lacticolor appeared in both sexes, some of the d s and some 

 2 s being lacticolor, others of each sex normal. Some of the males 

 used as fathers in these experiments were first crosses, otheis 

 were heterozygous males of the second geneiation, which had 

 lacticolor sisters. One F, male (exp. xhv. '03), which had two 

 lacticolor grandparents, when paired with a lacticolor $ had only 

 nor-mal offspring, showing that in F^ pure dominant males occur, 

 in addition to heterozygotes, as is expected on the Mendelian 

 theory. 



Proc. Zool. Sec— 1906, Vol. I. No. IX. 9 



