The Formation of Vegetable Mould Through the Action of Worms with Observations on Their Habits

afforded alimentary canal amount of earth animals annually brought apex appears astronomy base Beagle beneath bristles buried canals of worms castings of worms Castings similarly collected cinders clef was struck conclusion conspicuous continually recurrent cause creatures Darwin says Darwin's authority Darwin's observation depth digestion doubt drawn earth-worms Earthworms exhibit facts field geological gizzard gradual accumulation ground habit half-decayed leaves humus-acids illustration instance instinct intelligence intestine land largest castings layer of lime leaf Maer Hall manner mouths natural history Natural Selection naturalist needles night number of worms objects left omnivorous organic organic unity Origin of Species ounces particles partly penetrate pharynx pine-leaves plants ploughed pots remarkable respect result rocks scientific seized Silchester slope soil species Staffordshire stones struggle for existence surface swallow thickness tion tons per acre treble clef triturate turf undermined by worms vegetable mould viscid walls whole worm-burrows worm-castings worms drag worms have played