THE ORIGIN AND HISTORY OP THE DOG. 5 



habits. This is rendered clearer when the changes in the 

 habits and instincts of the supposed wild ancestors of the 

 dog under conlinement and domestication are considered, 

 and the corresponding change in dogs when they become 

 feral. Thus most of the wild forms alluded to, strictly 

 speaking, do not bark as the dog ; but cases are on record 

 that show that such wild forms may learn to bark in con- 

 finement, while dogs that have become feral lose this trait, 

 and so with many other characteristics of the dog. 



The great diversity of physical and psychic character- 

 istics in the different breeds of dogs is to be explained 

 by crossing, selection, and environment. 



Crossing tends to modify in all respects the existing 

 form and character, selection to ^x a type, and environ- 

 ment to alter particularly the more transient or less 

 permanent characteristics, and produce strains, or those 

 combinations of form and qualities more difficult to de- 

 tect and often affecting the vitality of the breed. 



To illustrate the last statements : a highly-bred bulldog 

 was crossed with a similarly well-bred greyhound, with 

 the result that, in a few generations, the bulldog form was 

 scarcely discernible, though the effects were manifest in 

 the stamina and psychic characteristics for many genera- 

 tions. This interesting experiment is given at length in 

 Stonehenge's work on the dog, and illustrated by cuts of 

 the animals produced. That the greyhound is such a 

 specialist is doubtless owing to the fact that, for a long 

 period in Britain alone, he has been used for the sole 

 purpose of coursing rabbits, in connection with which pub- 

 lic competitions have been instituted, leading to choice 

 of those best suited for breeding purposes and the great- 



