332 CHARLES E. STOCKARD AND A. L. JOHNSON 



A brother of this animal, 11445 (fig. 3), was mounted in 

 an entirely different manner by the same taxidermist. The 

 skin, carefully prepared so as to avoid any possible stretch- 

 ing, was completely stuffed so that there were no folds or 

 wrinkles and the full extent of its area could be demonstrated. 

 Figures 5 and 9 show this dog as it would have looked had 

 its body frame been such as to take up the excess skin. 



The excessive overgrowth of skin in either pure line dog 

 breeds or these hybrids is associated with developmental 

 arrests resulting in both histological and cytological abnor- 

 malities of the pituitary gland. The defective condition of 

 these pituitary glands is illustrated and discussed in a further 

 section of this study. 



An exaggerated overproduction of skin comparable with 

 the most extreme conditions found among the F 2 bulldog- 

 bassethound hybrids is obtained by backcrossing the F x hybrid 

 with the pure bulldog stock. Figure 1 in plate 63 shows the 

 bulldog to have a degree of looseness of skin about the neck 

 and shoulders. In this case, however, the wrinkles about the 

 head and face are due to suppression of the underlying parts 

 of the face and upper jaw without equal reduction in the 

 rather normal amount of overlying skin. If the reader will 

 imagine the skeletal structures of the muzzle of the dog in 

 figure 2 to be flattened back as in the bulldog, he may readily 

 appreciate that the skin covering would also be pressed back 

 in accordion fashion, forming the cheek folds of the bulldog. 

 Figure 2 is of an F! bassethound-bulldog hybrid having some- 

 what looser skin than the bulldog. 



Figures 3 to 6 in plate 63 show the skin conditions in the 

 hybrids derived from backcrossing the F! on the bulldog. 

 Figure 3 shows sagging skin about the approximately half- 

 typed bulldog head, and figures 4, 5 and 6 illustrate the high 

 degree of skin overgrowth in these hybrid animals. 



The excess in skin area over body size is a definite case 

 of structural disharmony. The size of the skeletal frame and 

 the muscular form are far too small and out of accord with 



