Page:Proceedings of the Royal Society of London Vol 60.djvu/507

Rh of sensation must be regarded as indicating a restored conductivity of the divided nerve. He holds that the theories which have hitherto been advanced to account for early return of sensation apart from reunion of the nerve, are inapplicable to cases where early return of sensation occurs from suture, performed after the lapse of several months from the time of section. The imperfect return of motion he takes to be fully explained by the fact that the muscles have undergone great trophic change, or indeed total destruction, and that, therefore, their restitution must be slow, or may even be impossible.

IV. Microscopical examination of the portions removed previous to suture.

Both the central and peripheral ends of nerves which had not reunited in any way, contained young nerve fibres grouped in bundles, each bundle containing, as a rule, many fibres. The fibres contained an axis-cylinder lying in the centre of a clear, well-defined zone, which, again, contained a granular, myeline deposit, while spindleshaped nuclei were attached to the sides of the fibres at frequent intervals. Where the ends of the nerve were united by a cicatricial segment without conductivity being restored, the examination of the segment showed a dense network of connective tissue containing in its meshes bundles of young fibres.

The portions excised from the nerves involved at the seat of fracture showed at their central ends a normal structure, but elsewheie no trace of old myeline fibres, nor of degenerated fibres ; but the section was made up of young fibres in bundles, which bundles were of only slightly greater diameter than the old myeline fibres, and often surrounded by a delicate sheath. At the point of transition from old to young fibres, many of the old myeline fibres contained an enlarged nucleus, with one or two distinct young fibres lodged between the sheath of Schwann and the myeline sheath. In other cases the number of young fibres lying in a similar position was greater. All stages up to complete replacement; of the old myeline sheath and axis-cylinder by young fibres were found.

V. Deductions from the microscopical examination. 1. Degeneration :—

(a) That there is no evidence of ascending degeneration of the kind described by Krause after interruption of a nerve.

( b) That the old axis-cylinder and myeline sheath are destroyed in the peripheral segment, and in the ultimate portion of the central segment.

2. Regeneration :—

(a) That young nerve fibres are developed in the peripheral segment, as well as in the end of the central segment, and that even while there is no connexion between the two ends.