SEX CONDITIONS 



secondary sex character. In no diploid males 

 has there been a significant shortening of an- 

 tennae which would be considered a tendency to- 

 ward intersexuaLity . Such stability of second- 

 ary sex characters is discussed on the basis of 

 the sex allele being a differential chromosome 

 segment. Female antennae are shorter chiefly 

 because of fewer segments. Diploid males have 

 a tendency toward fewer and loneer antennal seg- 

 ments than haploid males. Fewer antennal seg- 

 ments in the diploid male are not regarded as 

 the result of intersexuality but as an indirect 

 effect of chromosome number. 



Definite types of reactions characteristic 

 of sex are found in Habrobracon. The females 

 sting caterpillars on which they subsequently 

 feed and lay their eggs. The males are entire- 

 ly indifferent to caterpillars, but they show 

 characteristic reactions towards females, such 

 as flipping wings, mounting, and beating with 

 wings and antennae in the process of mating. 



Gynanders (sex-mosaic individuals) occasion- 

 ally appear in bisexual fraternities . Gynandro- 

 morphic offspring from a .recessive female by a 

 dominant male show the maternal trait in the 

 male (haploid) parts, the paternal trait in the 

 female (diploid) parts. This evidence is con- 

 sistent with the theory of egg binuclearity . 

 Fertilization of one nucleus results in the fe- 

 male parts; development of the other without 

 fertilization results in the male parts. Gynan- 

 ders may have male heads, female abdomens, or 

 the reverse; one side may be male, the other fe- 

 nale; anterior left and posterior right may be 

 of one sex, the remainder of the other sex; male 

 islands may occur in female regions or female 



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