216 



GENETICS IN RELATION TO AGRICULTURE 



evidence has not admitted of an entirely satisfactory interpretation. 

 We shall consider one case, that which Goldschmidt has investigated 

 in Lymantria as an example of the results obtained by investigations of 

 this kind. 



Goldschmidt's investigations are concerned with Lymantria dispar, the 

 European gypsy moth, and L. japonica, its Japanese form. As may be 

 seen from Fig. 97, Lymantria is strongly sexually dimorphic, the females 

 are much lighter in color and larger than the males; japonica is somewhat 

 larger than dispar, but otherwise in general agrees with it. Goldschmidt's 

 investigations deal with the production of intersexual forms in crosses 



. 



FIG. 97. Typical forms and hybrids of Lymantria; 1 and 2, male and female of L. 

 dispar; 3 and 4, male and female of L. japonica; 5-16, hybrids combining male and female 

 characters. (After Goldschmidt.) 



between these two species. He has shown that with proper combinations 

 of different races of these two species, intersexes may be produced which 

 occupy all possible intermediate positions in a continuous series in which 

 maleness and femaleness are the two extremes. Thus female intersexes, 

 i.e., individuals which are of the chromosome constitution WZ, may be 

 obtained which range from those that show only a very slight develop- 

 ment of male characters in the feathering of the antennae to those which 

 are so nearly males that they show only a faint trace of their female 

 origin in a few minor characters. On the other hand, male intersexes 

 of the chromosome constitution ZZ may be produced ranging from 

 those which exhibit a few white flecks on the wings up to those which 



