GENETIC TYPE AND THE ENDOCRINES 57 



almost 150 F2 animals has erect ears, although many show 

 a semi-raised ear posture. The size of the ear among these 

 F2 combinations rarely approaches the large ear of the hound. 

 Some of the F 2 hybrids are excitable in behavior, resembling 

 the shepherd grandparent; others are less active and less 

 nervous, approaching the bassethound in disposition. 



Among the tall F2 animals, some show long, slender, shep- 

 herd-like legs while others have a less slender, rather fox- 

 hound typed leg. Some of the achondroplasic legs are slen- 

 derer and seem comparatively less shortened than others. 

 We shall discuss further the importance of bone quality after 

 other breed crosses have been considered. 



The F! bassethound-shepherd backcrossed with the shepherd 

 parent stock. Nine fertile matings were made between the F x 

 shepherd-bassethound hybrid and the pure shepherd stock. 

 The backcrosses were arranged in some cases between a 

 female Fj and the male shepherd and in others between the 

 female shepherd and the male Fj. The results were the same 

 for both kinds of matings. In all, sixty-two offspring were 

 produced from nine matings between the pure long legged 

 parent stock and the heterozygous short Fj. The average 

 litter size was about seven, the smallest litter containing only 

 two puppies, and the largest ten. The backcross hybrid pup- 

 pies were divided for leg length into approximately equal 

 groups of long legged and short legged individuals. If we 

 represent the factor for long leg by the letter I and the factor 

 for short by s and consider the germinal quality of the pure 

 shepherd as II and the hybrid Fj as si, we obtain the expected 

 50 :50 ratio of II and si combinations. The types of legs among 

 these backcross hybrids are either fully long as in the shepherd 

 or intermediately short as in the Fj shepherd-bassethound; 

 no pure ss legs are possible. 



In common language, these backcross hybrids would be 

 termed three-quarter shepherd, but, as may be seen by refer- 

 ence to any one character, such a fractional expression is 

 genetically entirely incorrect. For example, the long, non- 

 achondroplasic leg is not three-quarters shepherd but entirely 



