534 



GENETICS IN RELATION TO AGRICULTURE 



few males have been born and these have always proved sterile. The 

 hybrids are apparently very uniform. The female hybrids appear to have 

 no difficulty in parturition when bred to domestic bulls or bison bulls. 



FIG. 208. An Fi hybrid between a bison bull and an Aberdeen-Angus cow. Note polled 

 character. (From Journal of Heredity.) 



FIG. 209. Quinto Porto, five-eighths buffalo, three-eighths polled Hereford. A fertile bull 

 which displays the characters of both species. (From the Journal of Heredity.) 



When bred to bison bulls, the three-fourths hybrids which are produced 

 are intermediate between the bison and the hybrid, and one- fourth 

 hybrids produced by breeding an FI female to a domestic bull are inter- 

 mediate between the hybrid and domestic cattle. Bulls of these two 



