SEX INHERITANCE 111 
Chance combination of any sperm with any egg 
gives eight classes in F, which are the eight classes 
described above. In this case the presence of 
HH XX R hh XV 
Hh XX & 
HX-hX-HY-AY Sperm 
Fig. 36C.—Cross of horned to hornless race of sheep.’ (After Wood, 
photographs from Punnett.) 
