ch. xv.] EARTHWORMS, 1881. 301 



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 

 bringing earth to the surface in their castings, must under- 

 mine 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 natural history and 

 intelligence of worms, a part of the work which added great- 

 ly to its popularity. 



In 1877 Sir Thomas Farrer had discovered close to his 

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

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

 self the effects produced by earthworms 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." 



In the autumn of 1880, when the Poiver of Movement in 

 Plants was nearly finished, he began once more on the sub- 

 ject. He wrote to Professor Carus (September 21) : 



" In the intervals of correcting the press, I am writing a 

 very little book, and have done nearly half of it. Its title 

 will be (as at present designed), The Formation of Vegetable 

 Mould through the Action of Worms* As far as I can 

 judge, it will be a curious little book." 



The manuscript was sent to the printers in April 1881, 

 and when the proof-sheets were coming in he wrote to Pro- 

 fessor Carus : " The subject has been to me a hobby-horse, 

 and I have perhaps treated it in foolish detail." 



It was published on October 10, and 2000 copies were 

 sold at once. He wrote to Sir J. D. Hooker, " I am glad 

 that you approve of the Worms. When in old days I used 

 to tell you whatever I was doing, if you were at all inter- 

 ested, I always felt as most men do when their work is final- 

 ly published." 



To Mr. Mellard Reade he wrote (November 8) : " It has 

 been a complete surprise to me how many persons have 



* The full title is The Formation of Vegetable Mould through the Action 

 of Worms, with Observations on their Habits, 1881. 



