Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 SENSE ORGANS. 83 blood vessels and , which there form a complicated network of nervous fibres containing here and there ganglion cells. The nervous sys- tem possesses further peripheral apparatus, the sense organs, the function of which is to bring about the perception of certain conditions of the outer world as im- pressions of a definite mode of sensation (specifia energy of nerves* Joh. Miiller). These peripheral organs usually have the form
Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote elementarytextbo01clau Year: 1892-1893 SENSE ORGANS. 83 blood vessels and , which there form a complicated network of nervous fibres containing here and there ganglion cells. The nervous sys- tem possesses further peripheral apparatus, the sense organs, the function of which is to bring about the perception of certain conditions of the outer world as im- pressions of a definite mode of sensation (specifia energy of nerves* Joh. Miiller). These peripheral organs usually have the form of peculiarly arranged aggrega- tions of hair-shaped or rod-shaped nerve terminations (hair- cells, rod-cells of sen- sory epithelium) con- nected by fibrillffi with ganglion cells, through which under the action of external influences a move- ment of the nervous substance is set up, which travels to the central organ and there affects con- * In opposition to the differences in the quali- ties of the sensations produced by each indi- vidual sense organ (colour, tone). FIG. 80.—Nervous system of the frog (after Ecker). Olt olfactory nerves ; O, eye ; Op, optic nerve ; Iy. ganglion ; Xg, ganglion of vagus ; Spn 1, first spinal nerve ; Br, brachial nerve ; Sgl-10, the ten ganglia of the sym- pathetic system. Js, ischial nerve.
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