1. [SUB- 7.] Geol. A subdivision of a stage.
1859. Darwin, Orig. Spec., ix. 297. If the specimens come from different sub-stages of the same [geological] formation.
1906. Chamberlin & Salisbury, Geol., III. 383. The following are the American stages of the glacial period now recognized in the interior of North America…. The Champlain sub-stage (marine). The glacio-lacustrine sub-stage.
2. [SUB- 3.] An apparatus fixed beneath the ordinary stage of a compound microscope for the purpose of supporting mirrors and other accessories. Also attrib.
1888. Rutley, Rock-Forming Min., 13. Generally speaking, a sub-stage is unnecessary. Ibid., 26. Examination by ordinary Transmitted Light (or Sub-stage Illumination).
1890. Anthony’s Photogr. Bull., III. 96. A substage illuminator or condenser.
1896. Allbutt’s Syst. Med., I. 506. Abbé’s substage-condenser.
1902. Ross’s Catal., Swing-out Substage.
