[Late and med.L. tapētum (pl. tapēta in Probus), for L. tapēte carpet.]
1. Comp. Anat. An irregular sector of the choroid membrane in the eyes of certain animals (e.g., the cat), which shines owing to the absence of the black pigment; also tapetum lucidum or t. choroideæ.
1713. Derham, Phys. Theol., IV. ii. 102. This Illumination he speaks of, is from the Tapetum in the bottom of the Eye.
1799. Monthly Rev., XXX. 146. The posterior half of a cat’s eye … was immersed in a bason of water, and examined. The tapetum appeared very bright, the retina not having acquired sufficient opacity to become visible.
1869. H. Ussher, in Eng. Mech., 3 Dec., 270/3. A … shining appearance at the bottom of the eye, called the ‘tapetum’ or ‘carpet.’
2. Bot. The layer of epithelial cells which lines the inner wall of the sporangium in ferns, etc., or of the pollen-sac in flowering-plants.
1882. Vines, Sachs’ Bot., 437. The inner cell again forms four tabular segments which are parallel to the outer parietal cells and which constitute the tapetum.
1885. Goodale, Physiol. Bot. (1892), 171, note. The epithelium which lines the pollen-sac has been termed the Tapetum.
