Issue 10, pp. 753-832, October 1861, SMSJ

cl Termination of Nerv October,] towers (700 diameters) many fibres which appear to besingle when seen by lower powers, can be resolved intothree or more, all enclosed in the same transparent tissue.As the nerve-fibres approach their distribution, this transparentstructure becomes much spread out. It is intimatelyconnected with nerve-fibres and capillaries, and with themtonus a delicate expansion over the muscular fibres, and inother parts. Delicate libres also, in connexion with thenerves and capillaries, may be observed in it. In somecases this expansion seems to be incorporated with the sareolemma,and it is probable that in certain instances it isreally the structure which has received that name.Axis Cylinder and White Substance.— Beale has been led toconclude that in consequence of the free division of theaxis cylinder and white substance near the point of distributionof the nerve, a single fibre in the trunk of a nervemay earrry impressions to or from a much larger extent ofsurface than is generally supposed. The white substancewhich surrounds the axis cylinder gradually diminishes,until in the finer ramifications it is impossible to say that afibre consists of an axis cylinder and white substance, forits general appearance and refractive power are the same inevery part, except where the nuclei are situated. Bealeconsiders that the definite characters of the axis cylinderand white substance in the trunks of the nerve maybe dueto the gradual growth and altered relations of the fibreswhich occur during the development of the entire organism.In the ultimate ramifications the whole fibre seems to consistof a very transparent and perhaps delicately granularsubstance, but no tubular membrane, medullary sheath, or axiscylinder can be demonstrated as distinct structures.Qf the Formation of New Fibres.—In connexion with theterminal ramifications, new fibres are being continually developedby the division of the nuclei, and old ones undergoremoval. "The remains of the latter may, however, be seenin the form of very delicate fibres, in connexion with activenerve fibres. Beale regards much of the so-called connectivetissues between the elementary libres of muscle and insome other situations, as of this nature—as the remains ofstructures whose period of functional activity was past, andwhich have been removed, with the exception of this smallquantity of insoluble material.The method of preparing the specimens is then brieflydescribed. Observations were conducted principally on