GENETIC INTERSEXUALITY IN BIRDS 45 



(19 1 3) mated Pygaera anachoraeta females with P. curtula 

 males and back-crossed the F.i males to P. anachoraeta 

 females to get similar 'gynandromorphs'. He then examined 

 his material cytologically to find that the haploid number 

 for P. anachoraeta is 30 and for P. curtula 29. In the 

 spermatogenesis of the F.i males all 59 chromosomes 

 divided equationally so that the 'gynandromorphs' received 

 59 chromosomes from their hybrid father and 30 from their 

 mother. They were triploids 2X:3A (possibly +Y). 



Seiler (1937) obtained similar triploid intersexes in the 

 F.I of the mating of females of the tetraploid (4N=i2o) 

 parthenogenetic variety of Solenohia triquetrella with males 

 of the diploid (2n=6o) bisexual Niirnberg variety of the 

 same species. The intersexes had 90 chromosomes and 

 showed a mixture of male and female parts of varying 

 degrees of development. Seiler found no support in his 

 material for Goldschmidt's 'turning point' hypothesis. 



Birds. That sex-determination in the fowl is likewise a 

 matter of a quantitative balance between sex- and auto- 

 somes was strongly suggested by Crew and Munro's (1938, 

 1939) studies of gynandromorphism and lateral asymmetry 

 in birds. Several instances of lateral gynandromorphism in 

 the fowl have been reported. In such the size difference 

 between the two sides of the body can be of the order of 

 10-15 per cent, and the gonads are different, one being a 

 testis the other an ovary or ovo-testis. The explanation 

 offered was that non-disjunction of an autosome had 

 occurred to result in bilateral heteroploidy, there being the 

 gain of an autosome on the larger side, its loss on the smaller, 

 and that this disturbance of the quantitative balance be- 

 tween sex- and auto-somes was responsible for the gonadic 

 differences. 



