224 The Inheritance of Wing Colour in Lepidoptera 



of nigrosparsata (see Plate X, Fig. 2) on the other hand is seen to have 

 the black pigment concentrated in certain scales, the majority of yellow 

 scales being practically devoid of dark pigment. In contrast to the 

 case of iochalca however, the dark pigment appears to be concentrated 

 in the tip of the scale rather than at the base, which accentuates the 

 mottled effect already caused by the localisation of the black pigment in 

 a few scales. The few grey scales of iochalca scarcely affect the colour. 

 Mr Raynor has kindly given me data concerning several pairings 

 with iochalca. It appears to be recessive to A. grossulariata and to 

 breed true when mated together. A pairing between iochalca </ and 

 iochalca ? gave 13 females and 6 males, all iochalca. Another family 

 of iochalca J^ x albipalliata J gave 5 females and 1 male iochalca, and 

 12 males and 15 females of other varieties, 14 of these females being 

 lacticolor. It must of course be remembered that the inheritance of 

 t/his variety may be complicated by the fact that it probably never occurs 

 except in combination with lacticolor. Experiments are in progress 

 with a strain of this variety kindly given to me by Mr Raynor. 



Var. cupreofasciata. 



(See Plate IX, No. 59.) This variety has the melanic suffusion of 

 iochalca, restricted to the orange fascia and shoulder knot. It can be 

 seen that the fascia has exactly the same appearance as that in No. 60, 

 Plate IX, and may be contrasted with the bright yellow fascia of the 

 ordinary lacticolor insects (Nos. 55 and 56). Mr Raynor tells me that 

 insects of the variety cupreofasciata are invariably descended from 

 iochalca ancestry. 



V. The Yellow Pigment. 



The cause of the difiference in the intensity of the yellow pigment 

 in the pale and the deep varieties is a problem of considerable importance, 

 since it may possibly give a clue as to the nature of the factors which 

 determine the varying shades of colour. There are several possible 

 conditions which might account for these colour variations. 



(1) The pigment itself may vary in constitution, and consequently 

 in cplour. 



(2) The concentration of the pigment, which may be either diffused 

 or in the form of granules, may be increased in the deeper varieties. 



If the composition of the pigment varies the change need not be 

 very fundamental, but might merely consist in an alteration in the 



