378 Darwin and Geology 
matter, obtained later, and a woodcut. This little paper was confined 
to observations made in his uncle’s fields in Staffordshire, where 
burnt clay, cinders, and sand were found to be buried under a layer 
of black earth, evidently brought from below by earthworms, and to a 
recital of similar facts from Scotland obtained through the agency of 
Lyell. The subsequent history of Darwin’s work on this question 
affords a striking example of the tenacity of purpose with which 
he continued his inquiries on any subject that interested him. 
In 1842, as soon as he was settled at Down, he began a series of 
observations on a foot-path and in his fields, that continued with 
intermissions during his whole life, and he extended his inquiries 
from time to time to the neighbouring parks of Knole and Holwood. 
In 1844 we find him ‘making a communication to the Gardener's 
Chronicle on the subject. About 1870, his attention to the question 
was stimulated by the circumstance that his niece (Miss L. Wedgwood) 
undertook to collect and weigh the worm-casts thrown up, during a 
whole year, on measured squares selected for the purpose, at Leith 
Hill Place. Healso obtained information from Professor Ramsay con- 
cerning observations made by him on a pavement near his house in 
1871. Darwin at this time began to realise the great importance of 
the action of worms to the archaeologist. Atan earlier date he appears 
to have obtained some information concerning articles found buried on 
the battle-field of Shrewsbury, and the old Roman town of Uriconium, 
near his early home; between 1871 and 1878 Mr (afterwards Lord) 
Farrer carried on a series of investigations at the Roman Villa dis- 
covered on his land at Abinger; Darwin’s son William examined for 
his father the evidence at Beaulieu Abbey, Brading, Stonehenge 
and other localities in the neighbourhood of his home; his sons 
Francis and Horace were enlisted to make similar inquiries at 
Chideock and Silchester; while Francis Galton contributed facts 
noticed in his walks in Hyde Park. By correspondence with Fritz 
Miiller and Dr Ernst, Darwin obtained information concerning the 
worm-casts found in South America; from Dr Kreft those of Australia ; 
and from Mr Scott and Dr (afterwards Sir George) King, those of 
India; the last-named correspondent also supplied him with much 
valuable information obtained in the South of Europe. Help too ~ 
was obtained from the memoirs on Earthworms published by Perrier 
in 1874 and van Hensen in 1877, while Professor Ray Lankester 
supplied important facts with regard to their anatomy. 
When therefore the series of interesting monographs on plant- 
life had been completed, Darwin set to work in bringing the in- 
formation that he had gradually accumulated during forty-four years 
to bear on the subject of his early paper. He also utilised the skill 
and ingenuity he had acquired in botanical work to aid in the 
