LYMANTRIA DISPAR 33 



when truncate male was mated to a wild-type female and 

 the F.I wild-type males back-crossed to truncate females, 

 all the offspring were wild-type. The male had transmitted 

 to his offspring only that allele which he had received from 

 his mother. This matroclinous inheritance manifestly differs 

 from sex-linked inheritance for the character truncate is 

 distributed alike to both males and females. 



Metz and Schmuck (1929), using a sex-linked recessive 

 mutant swollen wing, found that swollen (^ x wild-type ? 

 gave all wild-type in F.i and that in F.2 swollen reappeared 

 in half the sons in the male families but in none of the 

 daughters of the female families. Sw^oUen ? x wild-type ^ 

 gave swollen sons, the swollen females all proving to 

 be male-producers. Thus the mutation had occurred in 

 the X and had not passed into the X^ through crossing- 

 over. 



A dominant mutant gene 'Wavy' was found by Metz and 

 Smith (193 1 ) to have occurred in the X^ and not to have 

 crossed over into the X. 



Thus it would seem that female-family-production is a 

 character determined by a dominant gene in the X chromo- 

 some (X^) and that male-family-production is a character 

 based on the recessive allele of this gene. 



The reason for this matroclinous inheritance — the male 

 transmitting to his progeny only those genes, sex-linked and 

 autosomal, that he himself received from his mother, his 

 spermatozoa lacking the paternal chromosomes — has been 

 revealed by cytological investigation (Du Bois, 1932). 

 Femaleness in Sciara is determined by the genie balance, 

 2X:2A=femaleness; iX:2A=maleness. The dominant gene 

 (X^) acts by so conditioning the cytoplasm that in the 

 X^X:2A constitution one paternal X is eliminated from the 

 nucleus. The XX:AA constitution leads to the elimination 

 of two paternal X's and to the soma of the male becoming 

 XO:AA. 



Lymantria dispar. The term intersex was first used by 

 Goldschmidt in 1925 to describe certain sexually aberrant 

 types that he had described in 191 1 and which had appeared 



