636 W. T. JAMES 



conditions ; and, as we have shown here, each breed runs true 

 to a form in behavior as well. 



It has been shown for these F 2 bassethound-shepherds 

 that the genetic relationship which determines physical form 

 and behavior among- the pure grandparents may be varied, 

 since some of the dogs are thin bodied, yet behave like 

 round bodied dogs. It was found that not only could the 

 physical form and behavioral nature be modified, but that 

 the same dog may behave like both the grandparental types 

 under different conditions. These animals are considered as 

 having a mixed constitution. Since the two behavioral types 

 can be mixed by cross breeding the grandparent opposite 

 types, and the results are quite different from either grand- 

 parent, it suggests that the homozygous relationship between 

 the genetic factors determining the behavior and physical 

 form which occurs in the pure grandparents is a result of 

 a correlation by selective breeding. The pure breed has been 

 selected and cross bred for generations on the basis of physical 

 form. It is reasonable to suppose that in breeding out 

 physical types the glandular and behavioral nature have also 

 been determined. The dogs have a selected physical form, 

 and in addition, a definite interorganismal structure and 

 iieurophysiological pattern which determines the performance, 

 resulting in pure constitution. This is emphasized also by 

 the data obtained on the inheritance of bones and glands. 



Although selection has played a part in isolation of the 

 pure types, this does not mean that it is responsible for the 

 linkage between the physical form and behavioral factors. 

 The linkage is natural, and can occur only if certain types 

 are cross bred. There could never be a true bassethound 

 with a German shepherd glandular system, for example. 

 Unless some artificial selection had been made, the chances 

 are thai the pure types would never have become isolated. 

 This would seem to be especially true after consideration of 

 the influence of mutation and breeding among animals reared 

 under natural conditions. 



