394 JOHN H. GEROULD 



The cuticula of the pupa, shed by the eclosion of the adult 

 (fig. 3, cf. fig. 3a) is white instead of yellow. The blue-green 

 hypodermis of the pupa, deprived of the normal yellow pigment, 

 secretes a white rather than a yellow cuticula. 



Observations made in 1921 confirm this, though the posterior 

 abdominal segments of the cast cuticula in some individuals 

 is tinged with brown, probably from excrementous pigments 

 voided by the butterfly before eclosion, and the anterior half 

 of the pupal shell including the wing cases is regularly faintly 

 yellowish and by transmitted light slightly greenish, as shown by 

 figure 3. 



IMAGO AND ITS EYE COLOR 



Color changes in the wings of a butterfly from such striking 

 mutants were to be expected, for it is well known from the work 

 of Mayer ('97) and others that the blood that flows into the 

 hollow scales shortly before eclosion provides the pigments of 

 the wing colors, yet no noticeable change. in the hue of the 

 scales was produced by the mutation. Thus the two broods 

 containing 25 per cent of blue-green caterpillars, viz., 1920, 

 a and ,3 (text fig. 1), were homozygous for white wing colors, 

 while a third, 9, was homozygous for yellow, a and ^ came from 

 white mothers and brother-sister matings within the large 

 family i [that included 95 white, 28 yellow females, or 3:lJ. 

 The relation between caterpillars and adults within family 

 i(3 was as follows: the 29 grass-green caterpillars that reached 

 maturity became '/S' adults = 18 white 9 9, 11 d^cT; the 

 12 surviving blue-green caterpillars became '-/S' adults = 6 

 white 9 9, 6 cf cf^. Q, on the other hand, came from a yellow 

 mother of this same family, i^^^ 9 , mated with a male of pure 

 yellow stock, s ^"cf , and the 33 mature offspring were all yellow 

 (10 9 9, 17cf cf from grass-green larvae, viz., 6, and 3 9 9, 

 3 (^ ^ from blue-green larvae, viz., 6). 



The blood of the imago, as seen by bleeding an emerging 

 butterfly, continues to be blue-green. It still lacks the yellow 

 element that would have been introduced into it from the 

 food had it not been, in all probability, neutralized or decolor- 

 ized by an inhibitor. It is evident that this inhibitor of yellow 



