2; in addition, cn, nerve cord; in, intestine; nf, parts of nephridium; on, external opening of nephridium; ov, ova; 1, testis.
1 with the addition of NF, neural fossa protecting the aggregated ganglia of the central nervous system; PVP, left posterior ventral process; PMP, posterior median process.
Nf, Nerve fibres.
Friction of Teeth.Let N be the normal pressure exerted between a pair of teeth of a pair of wheels; s the total distance through which they slide upon each other; n the number Of pairs of teeth which pass the plane of axis in a unit of time; then nf NI (63)
Tahir ultimately (820) i~eceived the ctntrnrnnrahin nf Vhnr~can wIlprc, lip ~, s,~,,l,-l;~ sct~hrich;na a practically independent Moslem dynasty (the Tahirids)i which ruled until about 873 in nominal obedience to Bagdad.
The black represents the cuticular product of the epidermal cells of the ocular area, taking the form either of))...,r,, f lens, cl, of crystalline body, cry, or of rhabdom, rhab; hy, hypodermis or epidermal cells; corn', laterallyplaced cells in the simpler stage, A, which like the nerve-end cells, vit' and ret', are corneagens or lens-producing; corn, specialized corneagen or lens-producing cells; vie, potential vitrella cells with cry', potential crystalline body now indistinguishable from retinula cells and rhabdomeres; vit, vitrella cell with cry, its contained cuticular product, the crystalline cone or body; ret', rhab', retinula cells and rhabdom of scorpion undifferentiated from adjacent cells, vit'; ret, retinula cell; rhab, rhabdom; nf, optic nerve-fibres.