ANIMAL MECHANISM.

Dunstan Times, Issue 3143, 13 November 1922, Page 2

ANIMAL MECHANISM.

At the in augural session of the British Association's ninetieth annual meeting at Hull, the President (Sir Charles Scott Sherrington) for his address chose as Iris subject “Some Aspects nV Avmmd AVeehavnsm.’’ He spoke about the nervous meclianism of the body, showing how muscular movement is evoked by the functioning of the nerve centres, which: form a system more or less their own. He showed, too. how we maintain an erect posture, explaining that on either side of the skull 1 is a minute water-filled hag. and inside it, attached hy hairiels, a tiny crystal-line- stone, whose pressure acts through these ha,d iets as a stimulus to the nerve. The nerve of eaeh gravity hag connects with the muscles of all the limbs and one side of the neck. In the ordinary erect posture Hie stimula-; tion hy the two gravity hags is equal, because the two gravity stones then *ie symmetrically. But if tin- head or the body is inclined to one side the stimulation at once becomes unequal, and there results exactly the right unsymmetrical action of the muscles to give the unsymnietrieal pose of limbs and neck required for stability. By these, same gravity hags the posturing of the eyes is maintained, these reactions o-f the head and eyes and body taking place when a bird wheels or slants in flight or a pilot stalls or hanks his areroplane. Passing to the growth of nerve-fibres. Professor Sherrington pointed out that it severed, say. hy a wound, the nerves die for their whole length between the point of severance and the muscles they serve. And then at, once the cut ends start re-growing from the point of severance. although for years they have given no signs of growth. The fibre tries to grow out to reach its far distant muscle. There are difficulties in its way, A multitude of mm-nervon.s repair cells growing in the wound spin scar tissue across the now -fibre’s path. Between these' alien cells Hie now nerve(ihre threads a tortuous way. avoiding and never joining any of them. This obstruction it may take many days J o traverse. Then it reaches a region where the sheath-cells of the old dead nervefibres lie altered' beyond ordinary recognition. But the growing fibre recognises them. Tunnelling through endless chains of them, it arrives finally, after weeks or months, at the wasted ninsele-fihresi which seem to have been its goal, for it connects with them ~t cnee. It pierces their covering membranes and re-forms with their substance junctions of characteristic pattern m-emhling the original that had died we eks or months before. Then its growth ceases, abruptly, as If began, and the wasted muscle recovers and Halost I miction is restored. How does the nerve-fibre tin cl its lost muscle microscopically miles away? What is the mechanism that drives and guides it ? .Marvellous though nerve regeneration he. its mechanism seems blind, for its vehemence is just a- great after amputation. when the parts lost can. of course', never he reached. It- blindness is sadly evident in the suffering caused hy the- useless nerve-sprouts entangled, in the scar of a healing, or headed. limb stump.