XL] MY NEW IDEAS 391 



must be quite unnecessarily strong, and there is thus a great 

 waste of wax. The whole conception of a supernatural 

 faculty for the purpose of economizing wax is thus shown to 

 be fallacious. Darwin's explanation entirely obviates this 

 difficulty, since it depends on the bees possessing intelligence 

 enough to reduce all the cellwalls to a nearly uniform thick- 

 ness, being that which is sufficient under all circumstances 

 to support the weight of the whole mass of comb and 

 honey. 



T/ie supposed " homing" instinct of dogs, etc. — In the year 

 1873 one of the many discussions on this subject took place 

 in Nature. I had suggested the immense importance of the 

 sense of smell in enabling dogs to find their way back along 

 a route they had been carried in a basket or covered cart ; 

 but, of course, there are cases which this will not explain. 

 I gave a summing up of the whole subject, and added a 

 new and very remarkable case which happened to my 

 friend Dr. Purland, whose amusing letters I have given in 

 Chapter XXVIII. This case is as follows : — 



" My friend lost a favourite little dog when he was living 

 in Long Acre. Three months afterwards he removed to 

 a house in another street about half a mile distant — a place 

 he had not contemplated going to, or even seen, before the 

 loss of the dog. Two months later (five months after the 

 loss of the dog) a scratching was heard at the front door, and 

 on opening it the dog rushed in, having found out its master 

 in the new house. My friend was so astonished that he went 

 next day to Long Acre to an acquaintance who lived nearly 

 opposite the old house (then empty), and told him his little 

 dog had come back. ' Oh,' said this person, ' I saw the dog 

 myself yesterday. He scratched at your door, barked a good 

 deal, then went to the middle of the street, turned round 

 several times, and started off towards where you now live.' My 

 friend cannot tell how much time elapsed between the dog's 

 leaving the old and arriving at the new house. If every 

 movement of this dog could have been watched from one door 

 to the other, much might have been learnt Could it have 



