Note 217a — Chapter V · THE ACTION OF WORMS IN THE DENUDATION OF THE LAND.
Reading edition
These statements are taken from Hensen in ‘Zeitschrift für wissenschaft. Zoologie.’ Bd. xxviii., 1877, p. 360. Those with respect to peat are taken from Mr. A. A. Julien in ‘Proc. American Assoc. Science,’ 1879, p. 354.