64 



INBREEDING AND OUTBREEDING 



^iZD 



Gametes of Pi 



f'' Is^-.^^ 't 



Gametes of Male 

 All direct s^regates 



■black Gray 



I/ong vestigial 



50.0^ ■ 50.o)S 



black Gray black Gray 



Long vestigial vestigial Long 



41.532 41.S3S a. 5% 6.4% 



Fia. 21. — Diagram to illustrate linkage breaks 'or "crossing-over" between the loci 

 containing the factors for the allelomorphic pairs. Gray body, black body and long wing — 

 vestigial wing in Drosophila. (After Morgan.) 



A complete visualization of this series of matings is 

 given in Fig. 21. 



