MENDELIAN SEGREGATION 



11 



somes conjugate in pairs, as shown diagrammatically 

 in Fig. 5, b. The chromosomes then separate (Fig. 5, c 

 and d) at the time of division of the cell , and one of the 

 resulting daughter cells gets the chromosome bearing 

 the vestigial, and the other daughter cell gets the 

 homologous chromosome, bearing the long factor. 

 Hence, there will be two kinds of eggs in the female 

 and two kinds of spermatozoa in the male. When 

 two such hybrid flies mate with each other, any 



FIG. 5. Diagram to illustrate in a heterozygous individual the con- 

 jugation and segregation of the chromosomes during "reduction." 



sperm may meet and fertilize any egg. The possible 

 combinations that result, and the frequency with 

 which they occur, are shown in the next diagram 

 (Fig. 6). 



As shown in this diagram, a spermatozoon bearing 

 the factor for long wings fertilizing an egg bearing 

 the same factor produces a fly pure for long wings; a 

 spermatozoon bearing the factor for long wings ferti- 

 lizing an egg bearing the factor for vestigial wings 

 produces a hybrid fly that has long wings. Hence 

 we say the long dominates the vestigial character. 



