Nerve tissue is composed of celis and fibres enclosed by connective tissue and supplied with bloodvessels and lymphatics ; it controls all the other tissues, it is not contractile, but generates and propagates. various impulses. The fibres and cells are arranged in masses called 'Nerve Centres,' or in cords called nerves. The former contain fibres and cells ; they generate, receive and transmit nervous impulses ; the latter are composed wholly of fibres which only transmit impulses. They have been likened to a galvanic battery ; the battery, like the nerve centres, generates, receives and transmits the electric current, while the wires, like the nerves, only conduct to and from the battery. They consist of small bundles of fibres called funiculi, bound together by a delicate sheath of membrane neurilemma ; these small bundles are again bound into large ones called fasciculi, the whole nerve being at last enclosed in a common sheath of connective tissue. Cellular tissue, owing to its colour, is called gray substance.

Fibrous nerve tissue is gray and white.