344 CHARLES R. STOCKARD AND A. L. JOHNSON 



from the Asiatic dog are closely similar to the character- 

 istics produced by a comparable mutation or series of muta- 

 tions among the European dogs in giving rise to the present 

 day bulldog breeds. The series of factors involved in the 

 two complexes may not, of course, be identically the same. 

 In addition, the mutant changes might be thought of as pro- 

 gressive and as not having gone equally far in all cases. 

 In the European bulldog, the point mutations effecting the 

 reduction in length of the mandible have not progressed so 

 far as in the Pekingese; the mandibular reduction has, how- 

 ever, been as fully accomplished in the European Brussels 

 griffon as in the Pekingese. 



It is quite evident after a long study of different breeds 

 with various distortions of the head and other body regions 

 that a series of very similar mutations tends to arise in the 

 germ plasm of many breeds, not only within limited localities 

 but in different regions of the world as well. These similar 

 mutations have appeared in apparently independent fashion 

 in the different dog stocks. 



In order to determine whether the characters of the Peking- 

 ese head are inherited in a manner similar to that for the 

 bulldog and the Brussels griffon, we have expended consider- 

 able time and effort in securing hybrid generations between 

 the Pekingese and the dachshund. This cross is not in itself 

 difficult to make, but it is very difficult to rear a satisfactory 

 number of the hybrids even under careful kennel conditions. 

 However, we have succeeded in accomplishing this. 



The F l dachshund-Pekingese hybrids. Two litters of six 

 and one litter of five F! dachshund-Pekingese hybrids have 



PLATE 67 



EXPLANATION OF FIGURES 



Cross between the long muzzled dachshund and the short muzzled Pekingese 

 for inheritance of head type as a further comparison with the expression of the 

 bulldog deformity in the bassethound-English bulldog cross. 



1 Dachshund 255$. 



2 Pekingese ARC 795872 (not a kennel dog). 

 3-7 F! hybrids. 



3 1888^. 4 2046 <?. 5 1886^. 6 2047$. 7 1891$. 



