THE PRACTICAL VALUE OF GENETICS 347 



environmental conditions; it coml^nos morphological characters 

 of both parents. 



Few other interspecific animal hybrids are of more than potential 

 value. Cattle have been crossed with the American bison, the 

 zebu, and other species with excellent results, but the hybrids are 

 not in common use (Fig. 194). Of these crosses Babcock and 

 Clausen say: "By long-continued selection it would be possible 

 to transfer many of the excellent qualities of the bison such as 

 superior coat, greater hardiness, resistance to tick and insect 



Fig. 194. — Quinto Porto, five-eighths bison, three eighths polled Hereford. 

 (With the permission of the Journal of Heredity.) 



infestation, and superior beef qualities to domestic cattle." The 

 hybrid between the zebu and our common cattle is sufficiently 

 resistant to tick-borne disease to be very valuable in the south- 

 western states according to Lush. Many other hybrids have been 

 recorded between domestic animals, such as the sheep and goat 

 and various species of fowls, l)ut they are chiefly of scientific 

 interest. 



An interesting effect of hybridization occurs in bees. The 

 Italian bee has long been recognized as superior to the black or 

 German bee and has become the most popular and widely kept 

 variety in the United States. It is resistant to one of the two 

 serious bee diseases and is not seriously affected by the bee moth, 

 while the black bee is susceptible to both diseases and when 



