THE FORMATION OF
VEGETABLE MOULD
THROUGH THE ACTION OF WORMS
WITH OBSERVATIONS ON THEIR HABITS.
BY CHARLES DARWIN, LL.D., F.R.S.
THIRTEENTH THOUSAND
WITH ILLUSTRATIONS
LONDON
JOHN MURRAY, ALBEMARLE STREET
1904
PRINTED BY
WILLIAM CLOWES AND SONS, LIMITED,
LONDON AND BECCLES.