One undoubted drawback is the tendency to deafness inherited by 

 so many. Why the pure white dog should be subject to this 

 defect would need an explanation of too scientific a nature to make 

 it admissible within the scope of this chapter. It may be noted, 

 however, as a matter of interest, that the presence of one or two 

 dark marks on the skin, not apparent in the coat, is sufficient to 

 maintain the hearing unimpaired. The correlation between the 

 total absence of pigment and the non-existence of the sense of 

 hearing has frequently stimulated the investigation of scientists. 

 The same phenonomen is manifested in the feline race, white cats 

 with blue eyes almost invariably being deaf. The curious thing is 

 that if one of the eyes is of a different colour the hearing is not 

 defective. Darwin's omission to speak of the bull terrier when 

 writing upon this topic is not surprising, considering that the 

 all-white dogs were not common in his time. They were a later 

 product. 



