No. 593] SHORTER ARTICLES AND DISCUSSION 313 



dilute orange. Orange is therefore incompletely dominant. The 

 heterozygote is an intermediate. The amount of orange pigmen- 

 tation, or the degree of its dilution, in the F t hybrids, however, 

 varies prodigiously with the season. The summer-bred hybrid 

 is of dilute orange ("apricot yellow") somewhat evenly dis- 

 tributed over the wind's, but in the small winter-bred individ- 

 uals, such as emerge in the greenhouse in December, the oramie 

 is restricted to a faint flush near the posterior (inner) margin of 

 the fore wings. 



But even though the underlying hereditary basis supports a 

 superstructure that varies widely, are these variations as such 

 inherited? The variety of eurythi mi called ariadne is small and 

 of a pale orange hue. This form appears under cold weather con- 

 ditions only. Its dwarf'ness is due 

 pillar to feed during the late fall 

 abundantlv supplied. The shortness of the day evidently is a 

 factor in checking the feeding. The caterpillar forages actively 

 at mid-day, but becomes sluggish before nightfall, yet it matures 

 even while it is not feeding, and hence produces a dwarfed pupa. 

 The pale color may be readily explained by the supposition that 

 the elaboration of chromogenic substances in the blood of the 

 pupa is checked by the cold so that these materials ripen in the 

 scales of the wings merely into faint orange and yellow. 



Ariadne's progeny in June are not ariadne, but a large and 

 brilliantly .orange insect. Are ariadne' s size and hue, therefore, 

 not inheritable, but dependent wholly upon the environment ? 

 At first thought this would seem to be the fact, and this was evi- 

 dently the view of the matter presenting itself to Punnett when 

 he stated that such variations are not inherited. We have seen, 

 se that this organ- 

 i particular way under these particular con- 

 ditions. Its inherited organization compels, determines, this 



^Thete' seasonal variations are therefore transmissible, though 

 they are by no means "independent of climatic and other condi- 

 tions." May they, therefore, play no part in evolutionary 

 change? We should not yet be dogmatic as to this. The under- 

 lying hereditary basis in all probability is as susceptible to muta- 



chromosomal elements, as any other germ-plasm. It would seem 

 by no means impossible that the alternating phenotypes of A. 



that they are hereditary 



