NON-CRISS-CROSS INHERITANCE. 



273 



X's attached to one another; the yellow female should have, in 

 addition, a Y-chromosome from her father (Fig. 2, last line), the 

 wild type female an additional X-chromosome from her father. 

 Such chromosomes are, in fact, found in the maturation stages of 

 the eggs of these females (Fig. 3, b, c, d and c, f, g, h}. In both 



xx 



a 



c 



xx 



Y 



XX- 



g k 



FIG. 3. Oogonial plates of: a, wild type female (after Bridges); b, c, d, 

 triploid-X grey females (described in the text) ; e, f, g, h, double yellow fe- 

 males (described in text) ; i, non-disjunctional female of another origin (after 

 Bridges), having three sex-chromosomes, shown for comparison. In all the 

 figures are three pairs of autosomes. In the wild female (a) are two rod- 

 shaped X-chromosomes (one from the father and one from the mother). In 

 the triploid-X (b, c, d) and the double yellow (e, f, g, h) females is a single 

 V-shaped body, the two attached X-chromosomes from the mother (sometimes 

 with difficulty distinguishable from an autosome). In addition to these, there 

 is: in the triploid-X females (b, c, d) , a rod-shaped typical X-chromosome 

 (derived from the father and accounting for the grey color of the fly) ; in the 

 yellow females (e. f, g, /;), the typical Y-chromosome (from the father). In 

 the non-disjunctional female previously described by Bridges (i), the three 

 sex-chromosomes are a Y-chromosome and two X-chromosomes not attached 

 by their ends. 



