1877-] ^ WORMS. • 393 



therefore be conveniently considered in this place. This 

 subject was one which had interested him many years-before 

 this date, and in 1838 a paper on the formation of mould 

 was published in the Proceedings of the Geological Society 

 (see vol. i. p. 255). 



Here he showed that "fragments of burnt marl, cinders, 

 &c., which had been thickly strewed over the surface of sev- 

 eral meadows were found after a few years lying at a depth 

 of some inches beneath the turf, but still forming a layer." 

 For the explanation of this fact, which forms the central idea 

 of the geological part of the book, he was indebted to his 

 uncle Josiah Wedgwood, who suggested that worms, by bring- 

 ing earth to the surface in their castings, must undermine 

 any objects lying on the surface and cause an apparent 

 sinking. 



In the book of 1881 he extended his observations on this 

 burying action, and devised a number of different ways of 

 checking his estimates as to the amount of work done.* He 

 also added a mass of observations on the habits, natural his- 

 tory and intelligence of worms, a part of the work which 

 added greatly to its popularity. 



In 1877 Sir Thomas Farrer had discovered close to his 

 garden the remains of a building of Roman-British times, 

 and thus gave my father the opportunity of seeing for him- 

 self the effects produced by earthworms' work on the old 

 concrete-floors, walls, &c. On his return he wrote to Sir 

 Thomas Farrer : — 



" I cannot remember a more delightful week than the last. 

 I know very well that E. will not believe me, but the worms 

 were by no means the sole charm." 



* He received much valuable help from Dr. King, of the Botanical 

 Gardens, Calcutta. The following passage is from a letter to Dr. King, 

 dated January 18, 1873 : — 



" I really do not know how to thank you enough for the immense 

 trouble which you have taken. You have attended exactly and fully to 

 the points about which I was most anxious. If I had been each evening 

 by your side, I could not have suggested anything else." 



