38 THE RIDDLE OF THE HERON'S TOE 



steep wood facing north, about a mile across country from 

 her place of temporary detention, and formed earths there 

 which continued to be inhabited for many years after. 



XI 



We know a lot more than our ancestors did, we moderns ; 

 The Riddle ^ut ^ ne more we learn the deeper becomes our 

 of the conviction that there remains a lot more to 

 Herons oe j earn Such was the reflection brought home 

 to me lately by a question from a correspondent about a 

 peculiarity in the structure of one of our most familiar 

 birds. ' Can you tell me,' he asked, ' what is the purpose 

 of the serrated inner edge of a heron's middle toe-nail ? ' 

 Now, had I only my own knowledge to rely on I must 

 have confessed my ignorance at once, wrapping it up, 

 perhaps, in some such delightful periphrasis as I once 

 heard employed by a witness under cross-examination 

 before a Parliamentary committee. He had been asked 

 a question to which his plain reply must have been, ' I 

 don't know ' ; but that would have given him too little 

 time for reflection, so he said, ' The honourable member 

 is now directing inquiry upon subject-matter, cognisance 

 of which, on my part, is a matter of impossibility.' Well, 

 I could not explain offhand why a heron should have a 

 toe toothed like a saw, but methought it would be easy to 

 dig the reason out of some book. Resource was had to 

 the writings of the best authorities upon ornithology, only 

 to find that while some of them ignore altogether the 

 peculiar serration on the middle digit of the heron, others 

 notice it without hazarding any conjecture as to its pur- 

 pose or origin. I was reduced, therefore, to assign to this 



