460 Genetics of Sex Determination 



in a mosaic way within the same individual. I have already presented 

 what I consider to be the proper explanation of this fact. Thus I can- 

 not help concluding that the triploid intersexes of Solenobia are to 

 be explained in the same way as all others; though a certain variabil- 

 ity in detail, based probably upon the unbalanced triploid condition 

 as such, may lead one to overlook the orderly background of main 

 events behind the sometimes disturbing details. 



In dioecious animals the sexual alternative based upon difiFerent 

 anlagen may be called a transition between monoecism and inter- 

 sexuality as far as the spatial separation in the anlage pattern is con- 

 cerned. The condition in insects and in Amphibia would be different 

 grades of such approximation to the monoecic pattern — approxima- 

 tion only because in these dioecious animals both sexes are never 

 functional in the same individual. This condition of approximation to 

 monoecism is itself genetically controlled by modifiers in control of 

 developmental patterns which affect sexual development without being 

 sex factors. This can be demonstrated best in Lymantria. Kosminsky 

 (1930, 1935) found a local race of this moth in Russia which, crossed 

 to other races, produces male intersexuality of a completely different 

 type from the usual one. Even organs developed from the same anlage 

 wdth alternative norm of reaction, like gonads and antennae, show a 

 spatial mosaic instead of the typical mosaic in time. I could show 

 (Goldschmidt, 1938c) that these special features are due to the 

 presence of some simple Mendelizing modifiers, which somehow 

 affect threshold levels in the development of these organs in the inter- 

 sexes, a close parallel to the (genetically unanalyzed) situation in 

 Solenobia. 



