196 PHYSIOLOGICAL GENETICS 



t urc of a wing may act by controlling a determination stream of 



definite quantity, speed of progress, pattern of flow, and action 

 upon different processes of morphogenesis and chemism. It is 

 surprising that these points of primary importance for the prob- 

 lem of gene action have never impressed other workers (with the 

 exception of J. S. Huxley). 



There is another point of greatest interest in connection with 

 the same work. II a male Lymantria dispar becomes intersexual, 

 the female wing color and wing structure appears upon the male 

 wing, as just described. If, vice versa, the female becomes 

 intersexual, the male wing color appears upon the female wing 

 at once, all over the wing. It is known that the pattern of wing 

 color is determined in a sensitive period before pupation, and we 

 have seen how in the male the determination stream flows across 

 the wing. The different behavior of the intersexual female must 

 then mean that the time relations in regard to the flow of the 

 stream across the wing are different in the female; even the 

 latest turning point could leave still enough time for the determin- 

 ing process for the male color (and structure) to spread over the 

 entire wing. (Actually, all time elements of growTh and differ- 

 entiation are different in both sexes, as analyzed in detail in 

 Goldschmidt 1933.) 



Giersberg (1929) has described and pictured a number of 

 intersexes in different Lepidoptera which in part demonstrate 

 beautifully the conception of the determination stream across 

 the wing, an interpretation that he also accepts. 



In recent years, Henke and Kuehn have applied the same con- 

 ception to the interpretation of their experiments in shifting the 

 wing pattern in Lepidoptera. The pattern aspect of the problem 

 will be discussed in a later chapter. Here we consider only their 

 proofs for gene action by controlling a stream of a determining 

 stuff. We refrain from reporting Henke's first experiments on 

 Saturnid moths, because no genetic work is available there, and 

 report only the work on the flour moth Ephestia kuehniella 

 where genetic, phenocopic, and experimental evidence are 

 available. 



Since the work of Sueffert (1925, 1927, 19296), Schwanwitsch 

 (1928-1929), and Kuehn (1926), it has been known that the com- 

 plicated pattern upon the wing of Lepidoptera is the result of 

 different arrangements of a number of always present constituent 



