Cambridge Library CoLLeCtion Books of enduring scholarly value Darwin Two hundred years after his birth and 150 years after the publication of ‘On the Origin of Species’, Charles Darwin and his theories are still the focus of worldwide attention. This series offers not only works by Darwin, but also the writings of his mentors in Cambridge and elsewhere, and a survey of the impassioned scientific, philosophical and theological debates sparked by his ‘dangerous idea’. The Formation of Vegetable Mould through the Action of Worms This book, published in 1881, was the result of many years of experimentation and observation by Darwin in the open-air laboratory of his garden at Down House in Kent. As he wrote in his introduction, the subject of soil disturbance by worms ‘may appear an insignificant one, but we shall see that it possesses some interest’. He goes on to demonstrate the immensity – in size and over time – of the accumulated tiny movements of soil by earthworms, and their vital role in aerating the soil and breaking down vegetable material to keep the topsoil, the growing medium for all plant life and thus vital to human existence, fertile and healthy. At a time when there is huge interest in growing food organically and keeping soil in good condition without using artificial fertilisers, Darwin’s insights are as important, and his descriptions of his experiments as fascinating, as they were in the late nineteenth century. Cambridge University Press has long been a pioneer in the reissuing of out-of-print titles from its own backlist, producing digital reprints of books that are still sought after by scholars and students but could not be reprinted economically using traditional technology. The Cambridge Library Collection extends this activity to a wider range of books which are still of importance to researchers and professionals, either for the source material they contain, or as landmarks in the history of their academic discipline. Drawing from the world-renowned collections in the Cambridge University Library, and guided by the advice of experts in each subject area, Cambridge University Press is using state-of-the-art scanning machines in its own Printing House to capture the content of each book selected for inclusion. The files are processed to give a consistently clear, crisp image, and the books finished to the high quality standard for which the Press is recognised around the world. The latest print-on-demand technology ensures that the books will remain available indefinitely, and that orders for single or multiple copies can quickly be supplied. The Cambridge Library Collection will bring back to life books of enduring scholarly value across a wide range of disciplines in the humanities and social sciences and in science and technology. The Formation of Vegetable Mould through the Action of Worms With Observations on their Habits Charles Darwin CAMbriDge UniVerSiTy PreSS Cambridge new york Melbourne Madrid Cape Town Singapore São Paolo Delhi Published in the United States of America by Cambridge University Press, new york www.cambridge.org information on this title: www.cambridge.org/9781108005128 © in this compilation Cambridge University Press 2009 This edition first published 1881 This digitally printed version 2009 iSbn 978-1-108-00512-8 This book reproduces the text of the original edition. The content and language reflect the beliefs, practices and terminology of their time, and have not been updated. THE FORMATION VEGETABLE MOULD, THROUGH THE ACTION OF WOEMS, WITH OBSERVATIONS ON THEIR HABITS. BY CHAELES DARWIN, LL.D., F.R.S. WITH ILLUSTRATIONS LONDON: JOHN MURRAY, ALBEMAELE STREET. 1881. The right of Tran&latum is rescroed. CONTENTS. INTRODUCTION . . . . .. P a ge 1-7 C H A P T EE I. HABITS OF WORMS. Nature of the sites inhabited—Can live long under water—Nocturnal—Wander about at night—Often lie close to the mouths of their burrows, and are thus destroyed in large numbers by birds—Structure —Do not possess eyes, but can distinguish between light and darkness—Eetreat rapidly when brightly illuminated, not by a reflex action—Power of atten- tion—Sensitive to heat and cold—Completely deaf —-Sensitive to vibrations and to touch—Feeble power of smell—Taste—Mental qualities—Nature of food—Omnivorous—Digestion—Leaves before being swallowed, moistened with a fluid of the nature of the pancreatic secretion—Extra-stomachal digestion—Calciferous glands, structure of—Cal- careous concretions formed in the anterior pair of glands—The calcareous matter primarily an excre- tion, but secondarily serves to neutralise the acids generated during the digestive process . 8-54 iv CONTENTS. CHAPTER II. HABITS OF WORMS—continued. Manner in which worms seize objects—Their power of suction—The instinct of plugging up the mouths of their burrows—Stones piled over the burrows— The advantages thus gained—Intelligence shown by worms in their manner of plugging up their burrows —Various kinds of leaves and other objects thus used—Triangles of paper—Summary of reasons for believing that worms exhibit some intelligence— Means by which they excavate their burrows, by pushing away the earth and swallowing it—Earth also swallowed for the nutritious matter which it contains—Depth to which worms burrow, and the construction of their burrows—Burrows lined with castings, and in the upper part with leaves—The lowest part paved with little stones or seeds— Manner in which the castings are ejected—The collapse of old burrows—Distribution of worms— Tower-like castings in Bengal—Gigantic castings on the Nilgiri Mountains—Castings ejected in all countries . . . .. Page 55-128 CHAPTER III. THE AMOUNT OF FINE EARTH BROUGHT UP BY WORMS TO THE SURFACE. Kate at which various objects strewed on the i-uiface of grass-fields are covered up by the castings of worms —The burial of a paved path—The slow subsidence of great stones left on the surface—The number of worms which live within a given space—The CONTENTS. v weight of earth ejected from a burrow, and from all the burrows within a given space—The thickness of the layer of mould which the castings on a given space would form within a given time if uniformly spread out—The slow rate at which mould can increase to a great thickness—Conclusion Page 129-175 CHAPTEE IV. THE PART WHICH WORMS HAVE PLAYED IN THE BURIAL OF ANCIENT BUILDINGS. The accumulation of rubbish on the sites of great cities independent of the action of worms—The burial of a Eoman villa at Abinger—The floors and walls penetrated by worms—Subsidence of a modern pavement—The buried pavement at Beaulieu Abbey —Koman villas at Ched worth and Brad ing—The remains of the Eoman town at Silchester—The nature of the debris by which the remains are covered—The penetration of the tesselated floors and walls by worms—Subsidence of the- floors-— Thickness of the mould—The old Eoman city of Wroxeter—Thickness of the mould—Depth of the foundations of some of the buildings—Conclusion 176-229 CHAPTEE V. THE ACTION OF WORMS IN THE DENUDATION OF THE LAND. Evidence of the amount of denudation which the land has undergone—Subaerial denudation—The deposi- tion of dust—Yegetable mould, its dark colour and