Page:Life in Motion.djvu/117

Rh life are semi-fluid. If we traced a nervefibre to the brain or spinal cord, we would find it starting from a process, or, as we call it, a pole, of a nerve-cell. When we trace it to a muscular fibre we find it loses the white substance of Schwann, and the axis-cylinder of the nerve-fibre pierces the sarcolemma, or sheath of the muscle-fibre, and ends in what

is called an end-plate. The end-plates, seen in the diagrams (Figs. 51 and 52) vary in form and general appearance. Sometimes they consist of very slender fibres, produced by the splitting up of the axis-cylinder, and forming a network; but usually they take the appearance of irregularly shaped granular masses or discs.

As a rule, each muscle-fibre has a