Questions and Problems 515 



7. If the tetraploid female in problem 5 is XXXX and is crossed with 

 a normal XY diploid male, what should be the ratio of the sexes of the 

 triploid offspring? If the tetraploid female is ZZWW as in problem 6, 

 and it is crossed with a normal ZZ diploid male, what should be the sex 

 ratio in the triploids. Would such tetraploid X diploid crosses throw any 

 light upon the question of the heterogametic sex? 



8. Is heteropycnosis confined to sex chromosomes or to the higher 

 plants ? 



9. What would be the offspring of the following crosses in Jones's 

 maize : 



Sksk TsotSi X sksk ts2ts-2 

 Sksk ts2ts2 X Sksk ts2ts2 

 Sksk Ts2ts2 X sksk Ts2ts2 



