150 LIFE OF 



for his experiments. Those on the movements of stems 

 and roots were still in progress. The hours passed like 

 minutes. I had to leave. Precious memories of that 

 visit remain." 



Yet once more, in 1881, the famous publishing 

 house of Murray issued a new work his last by 

 the great illuminator of Nature. Its subject was one 

 which no one save those who knew him could have 

 expected. It dealt with "The Formation of Vegetable 

 Mould, through the Action of Worms, with Observations 

 on their Habits," and in it the lowly earthworm was at 

 last raised to its true rank as the genuine preparer and 

 possessor of the soil. Both Gilbert White and Edward 

 Jenner had been impressed with the work earthworms 

 do in nature, but no one had written extensively on the 

 subject till Darwin himself, in 1837, read a short paper 

 on the " Formation of Mould " before the Geological 

 Society of London (published in the fifth volume of the 

 Society's Transactions), showing that small fragments 

 of burnt marl, cinders, &c, which had been thickly 

 strewed over the surface of several meadows, were found 

 after a few years lying at the depth of some inches 

 beneath the turf. It was suggested to him by his relative 

 Mr. Wedgwood, of Maer Hall, in Staffordshire, that this 

 was due to the quantity of fine earth continually brought 

 up to the surface by worms in the form of castings. 

 Observation and experiment were to settle the question 

 in the usual Darwinian manner, and many a portion of 

 soil was watched. One experiment lasted nearly thirty 

 years, for a quantity of broken chalk and sifted coal 



