LINKAGE 



71 



large number of species in which Mendelian inheri- 

 tance has been discovered; but there are several rea- 

 sons why more cases have not been recorded. In 

 the first place, the number of chromosomes is generally 

 large compared with the number of characters that 



f^m0 





Fig. 27. — Barred Plymouth Rock female by Lang.shari male. Compare 

 similar cross in Abraxas for scheme of inheritance. 



have been studied in sucli a way that linkage would 

 be noticed. Thus, there is httlc chance of finding 

 two factors lying in the same chromosome. Sec- 

 ondly, unless this linkage is close, it might easily 

 escape detection, especially when the number of off- 



