128 CHARLES E. STOCKARD 



Boston terrier-dachshunds (the breed name of the mother is 

 placed before the hyphen). 



These F l hybrids, when bred inter se, give rise to an F 2 

 generation showing the same differences in leg conditions as 

 have been described previously for the bassethound crosses. 

 The long straight legs of the Boston terrier grandparent 

 reappear in about one-fourth of the F 2 animals, as would be 

 expected in Mendelian segregation for a single factor recessive 

 character. About three-fourths of the F 2 generation have 

 achondroplasic short legs, but again, not all are equally 

 short. The majority of the short legs are intermediate like 

 those of the F 1 parent while about one-third are very short 

 and probably ss in genotype, like the dachshund grandparent. 

 In other words, the short legs of the dachshund are trans- 

 mitted as a single factor dominant character and the F 2 

 generation is approximately divided into the expected ratio 

 of one short leg ss to two intermediate short si to one normal 

 long II. 



Plate 30 shows photographs of sixteen F 2 hybrids. Of the 

 two animals in figures 6 and 7, figure 6 illustrates the homo- 

 zygous pure short leg condition and figure 7 the intermediate 

 heterozygous leg condition. Great differences in size are 

 found among litter mates, as illustrated by the animals in 

 figures 1 to 5. Further points of interest shown by these 

 animals will be discussed in other connections. 



Plate 31 gives a family tree of the skeletons in this cross. 

 The low skeleton of the dachshund is shown in figures 1 and 

 2. The characteristic shortness and typical posture of the 

 leg bones are evident. The skeleton of the Boston terrier 

 is shown in figure 3. The deformed skull and short, bent 

 tail offer marked contrast to the long skull and fine tail of 

 the dachshund skeleton, while on the other hand the legs 

 of the Boston terrier show to great advantage over those of 

 the dachshund. An F l skeleton is seen from two aspects in 

 figures 4 and 5. Figures 6 to 11 show four skeletons from F 2 

 animals; a puppy skeleton is shown in two aspects (figs. 6 

 and 7), a midget with intermediate legs (fig. 8), a short leg 



