GENETIC TYPE AND THE ENDOCEINES 125 



few cases of several allelomorphs for the same gene are 

 known, and this probably means that an original gene had 

 mutated in more than one way or by more than a single 

 type of change. 



The short legged condition not only occurs in several dog 

 breeds but, as will be recalled from our earlier discussions, 

 a closely similar growth reaction is found among many widely 

 different animals, such as cattle, sheep, birds, and the human 

 race. No one can deny that the mutations giving rise to 

 the distorted short extremities in these very different forms 

 may have occurred independently. Among the dogs, however, 

 there is a possibility that man introduced the short legged con- 

 dition into the different breeds from one original mutant 

 source. The history of several recent short legged breeds 

 would indicate that they doubtless were produced in this 

 manner. In spite of this possibility there is strong probability 

 that several of the short legged dog breeds have entirely 

 independent origins. There is no satisfactory evidence to 

 indicate that the bassethound and the dachshund derived 

 their short legs from a common ancestral origin, yet the 

 chance for this must be acknowledged since both breeds have 

 been developed in nearby European countries. However, the 

 Pekingese, with its short achondroplasic legs, arose in a far 

 distant region of Asia, and from old illustrations we are led 

 to believe that the breed has existed as such for more than 

 a thousand years. There is little possibility that the origin 

 of the achondroplasic legs of the Pekingese dog is in any 

 way connected with the origin of short legs in the European 

 dogs, or vice versa. 



With these questions and problems in mind it seemed 

 highly desirable to widen our study of the short leg character 

 by further breed crosses using the dachshund and Pekingese. 



THE EXTREMITIES IN THE DACHSHUND-BOSTON TERRIER CROSS 



Except for its dwarf size, the dachshund is very similar in 



general type to the bassethound. The same extreme degree 



of localized achondroplasic growth is found in the extremities, 



