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 



FIG. 27. Barred Plymouth Rock female by Langshan male. Compare 

 similar cross in Abraxas for scheme of inheritance. 



have been studied in such a way that linkage would 

 be noticed. Thus, there is little 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- 



