These are shown with coulter and share and also with wheels, which had in earlier times been fitted to ploughs by the Greeks and also by the natives of Cis-Alpine Gaul (Pliny, Hist.
The working parts of the plough are the coulter, the share, and the breast or mould-board.
The coulter (either knife or disk) and sometimes a skim-coulter (or jointer) are attached adjustably to the beam, so as to act in the front of the share.
The coulter is a knife or revolving disk which is fixed so that its point clears the point of the share.
The skim-coulter is shaped like a miniature plough, substituted for or fixed in front of the coulter; it is used chiefly on lea land, to pare off the surface of the soil together with the vegetation thereon, and turn it into the previous furrow, where it is immediately buried by the furrow slice.
In operation the coulter makes a perpendicular cut separating the furrow-slice which is divided from the "sole" of the furrow Crested Furrow.
Within the last few years Prof. John Coulter and Dr C. J.
(Oxford, 1890); Solereder, Systematische Anatomie der Dicotyledonen (Stuttgart, 1899); van Tieghem, Elements de botanique; Coulter and Chamberlain, Morphology of Angiosperms (New York, 1903).
5, and various publications of the United States Forestry Division for forest and forest reserves; Porter and Coulter, Synopsis of the Flora of Colorado (1879); and scattered papers in scientific periodicals.
As Coulter and Chamberlain express it, " the habitats of the Gymnosperms to-day indicate that they either are not at home in the more genial conditions affected by Angiosperms, or have not been able to maintain themselves in competition with this group of plants."
(Jena, 1892); Coulter and Chamberlain, Morphology of Spermatophytes (New York, 1901); Rendle, The Classification of Flowering Plants, vol.