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.
In operation the coulter makes a perpendicular cut separating the furrow-slice which is divided from the "sole" of the furrow Crested Furrow.
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."