300 



THE CONTINUITY OF THE RACE 



B 



C 



-*5 



3 

 3 



a 



B 

 b 



C 

 c 



a 



A 



B C 



Fig. 19.4. Diagrams illustrating linkage and crossing over. Compare with Fig. 15.3. (Based 

 on White, Animal Cytology and Evolution, by permission Cambridge University Press.) 



