Quain's elements of anatomy . g in thesituation of a node of Ranvier (fig. ). The axis-cylinder participatesin the division ; and since the white fibres frequently lose their medullarysheath shortly before they terminate, they are then represented by the 160 NEEVOUS SYSTEM. axis-cylinder and its ramifications, altliougli the primitive sheath maycontinne some little way along the branches after the medullary sheathhas ceased. By repeated division the fibres become smaller and smaller ;but whilst some of the resulting- small fibres may be simple, many arereally bundles of exquisitely fine fi
Quain's elements of anatomy . g in thesituation of a node of Ranvier (fig. ). The axis-cylinder participatesin the division ; and since the white fibres frequently lose their medullarysheath shortly before they terminate, they are then represented by the 160 NEEVOUS SYSTEM. axis-cylinder and its ramifications, altliougli the primitive sheath maycontinne some little way along the branches after the medullary sheathhas ceased. By repeated division the fibres become smaller and smaller ;but whilst some of the resulting- small fibres may be simple, many arereally bundles of exquisitely fine fibrils. The fibres bear nuclei, which probably appertain to the prolongationof the primitive sheath; the nuclei are common at the bifurcations ofthe fibres, where they are of a triangular or irregular shape. Thesepale fibres often join into plexuses; but their ultimate disposition indifferent parts will be treated of below. As has already been explainedthe original dark-bordered fibres which thus undergo division and Fig. Fig. 159.—Shall branch of a mttscular nerve op the frog, near its termina-tion, SHOWING DIVISIONS OF THE FIBRES. MAGNIFIED 350 DIAMETERS (Kolllker), a, into two ; h, into three. change, or which may proceed singly to end in a difierent and specialmanner, are commonly jorovided with a tolerably strong connective tissuesheath with nuclei, which, as it stands well apart from the dark bordersof the fibre, is very conspicuous (Henles sheath). This is derived fromthe perineurium which incloses the funiculi of the nerve-trunks, and, asthese part into smaller collections and single fibres, undergoes a coitc-sponding division, and finally sends sheaths along single fibres. Withinthe sheath of Henle fine longitudinal connective tissue fibres, with inter-spersed corpuscles, are seen surrounding the nerve-fibre or fibres. Thistissue is a prolongation of the endoneurium. In further treating of the termination of nerves, it ^ill be convenientto consider the sensory a
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