3. A longitudinal section at the juncture of a muscle and tendon. _a_, The juncture between the muscle and tendon. Note the many nuclei in both muscle and tendon. This is voluntary or striated muscle which make up the dermal, dermo-osseous and skeletal muscles. 4. A longitudinal section of heart muscle. _a_, Connective-tissue cell. _b_, Nucleus of a muscle cell. _c_, Cement line between the muscle discs. _d_, The cell or segment. 5. A bipolar ganglionic nerve cell. _a_, The nucleus. _b_, The nucleolus. _c_, The fibrillar structure. _d_, The medullary sheath. 6. A diagram showing the scheme of the peripheral nerve trunk. _a_, The neuraxis of the peripheral sensory neurone. _b_, The spinal ganglion of the superior or sensory root. _c_, The dendrite or peripheral nerve fiber of the sensory nerve. _d_, The nerve trunk. _f_, The sympathetic nerve ganglion connected with the spinal cord through the white and the gray ramus communicans. _e_, The neuraxis of the sympathetic neurone. _g_, Neuraxis or trunk of the motor neurone or nerve cell. _h_, The anterior horn of the gray matter of the spinal cord. 7. A diagram of a peripheral sensory neurone. _a_, The neuraxis which ends in the spinal cord or brain. _b_, The T-shaped division of Ranvier. _c_, The dendrite or sensory nerve fiber in the nerve trunk. _d_, The nucleus and nucleolus of the cell _e._, _f._ the axis cylinder process of the cell. _g_, The telodendrions or terminal branches of the dendrite or axis cylinder. 8. A schematic diagram of the sensory motor reflex. _a_, The telodendria. _b_, The dendrite. _c_, Nerve cell of the motor neurone. _d_, The motor neurone. _f_, The muscle fiber. _g_, The neuraxis of both sensory and motor neurones, the upper being the sensory. _h_, The nerve cell in the sensory ganglion. _i_, The sensory neurone or axis cylinder (nerve fiber). _j_, The skin with peripheral telodendrion of sensory neurone. ] _Neurones_ are devoted to the maintenance of functions. Reproductive neurones are so arranged as to receive afferent nerve impulses from other tissues; emissive neurones give off efferent nerve impulses. The former are sensory neurones; the latter are motor neurones if connected with muscles, and excito-glandular if connected with gland cells. The basis, then, of the nerve system is a series of neurones, with projecting and association processes, coördinated for the purpose of performing specific actions manifested either by motion, by trophic changes, or by the apperception of stimuli of a chemic, mechanic (tactile and auditory), thermal, or photic nature.