THE MUTATED GENE 



233 



independently. In this case, the same type of flow of a sub- 

 stance across the wing would lead to a perfectly regular pattern. 

 There can be no doubt that many patterns found in our models, 

 the wings of Lepidoptera, are of this type. Examples will be 

 discovered wherever mutant genes do not change the original 

 pattern of the species but superimpose upon it a process that 

 leads to a secondary pattern. This will frequently be the case 

 with sexual differences and also with mutants of the type of 



Fig. 44. — Pupal wing of Papilio podalirius. The part of the wing to the 

 left of the undulated line will degenerate, leaving only the tail. {From Sueffert, 

 1929, Zeitschr. Morph. Oek. 14, Fig. 9.) 



melanisms where a pigment covers the preexisting pattern in a 

 definite degree, which might be quantitatively graded by the 

 action of different allelomorphs or genes. A number of such 

 cases have been analyzed genetically (Goldschmidt 19216, 

 1924a; Federley, 1920; Kuehn and Henke, 1929-1936), but little 

 else is known that would permit going beyond these general 

 statements. The most important additional fact is that similar 

 patterns to those produced in these cases by genes may also be 

 produced by temperature action, e.g., melanic patterns of one 

 sex in Gastropacha (Standfuss, 1896), Lymantria (Kosminsky, 

 1909; Federley, 1907; Goldschmidt, 19226); general melanism in 

 Habrobracon (Schlottke, 1926); and Ephestia (Kuehn and 

 Henke, 1929-1936). In this group belong also such secondary 



