GENETIC TYPE AND THE ENDOCRINES 57 



almost 150 F 2 animals has erect ears, although many show 

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

 F-2 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 F 2 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 

 ether breed crosses have been considered. 



The F A 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 F x and the male shepherd and in others between the 

 female shepherd and the male F x . 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 F x . 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 / and the factor 

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

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

 50 :50 ratio of 11 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 F 1 shepherd-bassethound; 

 no pure 55 legs are possible. 



In common language, these backcross hybrids would lie 

 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 



