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Show 4 INTRODUCTION. spread out and cover up any object left on the surface. I was thus led to conclude that all the vegetable mould over the whole country has passed many times through, and will again pass many times through, the intestinal canals of worms. Hence the term " animal mould" would be in some respects more appropriate than that commonly used of "vegetable mould." Ten years after the publication of my paper, M. D'Archiac, evidently influenced by the doctrines of Elie de Beaumont, wrote about my "singuliere theorie," and objected that it could apply only to ''les prairies basses et humides ;" and that "les terres labounfes, les bois, les prairies elevees, n'apportent aucune preuve a l'appui de cette maniere de voir."* But M. D'Archiac must have thus argued from inner consciousness and not from observation, for worms abound to an extraordinary degree in kitchen gardens where the soil is continually worked, though in such loose soil they generally depo::;it their castings in any open cavities or within their old burrows instead of on the surface. Von Hensen estimates that there are * 'Histoire des progre~ de la Geologie,' tom. i. 1847, p. 224. INTRODUCTION. 5 about twice as many worms in gardens as In corn-fields.* With respect to "prairies elevees,'' I do not know how it may be in France, but nowhere in England have I seen the ground so thickly covered with castings as on commons, at a height of several hundred feet above the sea. In woods again, if the loose leaves in autumn are removed, the whole surface will be found strewed with castings. Dr. I{ing, the superintendent of the Botanic Garden in Calcutta, to whose kindness I am indebted for many observations on earthworms, informs me that he found, near Nancy in France, the bottom of the State forests covered over many acres with a spongy layer, composed of dead leaves and innumerable worm-castings. He there heard tho Professor of "Amenagement des Forets" lecturing to his pupils, and pointing out this case as a "beautiful example of the natural cultiva" tion of the soil ; for year after year the "thrown-up castings cover the dead leaves; "the result being a rich humus of great " thickness." • 'Zeitscb rift fiir wissenscbaft. Zoo Iogie,' B. xxviii. 1877, p. 361. |
