142 POPULAR SCIENCE MONTHLY. 



No doubt, to the many, who love more to gaze and marvel than to 

 question and reflect, all this will seem miserably inadequate as a clue 

 to one of the greatest mysteries of life. But enough, if I have indicated 

 my view of how the most inexplicable of instincts may have had their 

 origin; or rather, if I have shown how our utter inability to trace them 

 back to their origin tells nothing against the probability that they 

 all came into existence in accordance with those laws of acquisition and 

 heredity that we now see operating before our eyes. We cannot tell how 

 the pupa of the dragon-fly came by the instinct that prompts it to leave 

 the water and hang itself up to dry. But we may be able to explain 

 this quite as soon as to unveil the origin of the hooks by which it hangs 

 itself up. And if ever human intelligence should so trace the evolu- 

 tion of living forms as to be able to say, "Thus was developed the bill- 

 scale wherewith birds now break their way out of the shells," it will 

 probably be able to add, "and these were the experiences to which we 

 must trace the instinct that makes every little bird its own skilful 

 accoucheur." 



