322 CHARLES R. STOCKARD AND A. L. JOHNSON 



BOTH GIANT AND DWARF REACTIONS FOR BODY SIZE AMONG 

 F2 BASSETHOUND-BULLDOG HYBRIDS 



The two lower rows of skulls in plate 57 (figs. 8-21) are 

 from fourteen bassethound-bulldog F 2 hybrids. All photo- 

 graphs in the plate were reduced to the same degree, and the 

 skulls are therefore accurately comparable for size and shape. 



No two of the fourteen F2 hybrid skulls are closely alike 

 in all respects. In the first place, the group offers remarkable 

 differences in size; this is particularly outstanding in view 

 of the fact that the two ancestral stocks are of about the 

 same normal size, as are also the Fj hybrid parents. Figure 

 8 is somewhat oversized and quite bulldog-like. Figure 9 is 

 smaller and shows congenital absence of the entire nasal 

 bones, the only such case on record for the dog. Figures 10, 

 11 and 12 show varied conditions inclining toward the bulldog- 

 type. Figure 13, as well as figure 20, is decidedly small and 

 dwarf in type; figure 13 is rather bulldog-like and figure 20 

 is nearer the bassethound type. F 2 dwarfs similar to those 

 furnishing these two skulls are photographed from life in 

 plate 58 (fig. 7) and plate 59 (figs. 3 and 5). These plates 

 were arranged to show dwarfs standing close to their large 

 litter mates, and all animals were photographed at the same 

 age. All photographs were reduced to the same degree and 

 the animals are therefore directly comparable for size. 



In plate 57, the skulls in figures 14, 16 and 18 are giant 

 in size when compared with the parent stocks. These skulls, 

 as well as the animals from which they were obtained, exhibit 

 certain symptoms of acromegaly. In many of their features 

 the skulls resemble more closely the skull of the giant St. 

 Bernard dog than they do those of either parent stock. Plate 



Second generation bassethound English bulldog hybrids showing both giant 

 and dwarf body sizes among members of the same litter, as well as other growth 

 distortions, such as an excessive amount of skin area. 

 1 991 <J. 2 995$. 3 996$. 4 992^. 5 977^. 6 980^. 7 979 <?. 



(Figs. 1 to 4, litter mates; o to 7, litter mates.) 



