198

likely to be involved, but the same principle wouldoperate. Now if the length of the muscle can, through itsinput signal, be continuously varied without any loss ofthe automatic tension-to-load adjusting properties of thesystem, we have a simple neuromuscular unit whichpossesses the attributes of a prime mover, namelyvariable length and variable tension, the former set bythe endogenous position-control organisation of thenervous system, the latter set by external forces andinternal inertia loading the muscle.A comparable electrical system (such as the velodyne

constant speed regulator) will maintain constant speed withvariable load by the automatic adjustment of the servomotor’storque. The speed to be maintained constant can be set atdifferent values, or can be continuously varied by a secondservosystem while the property of automatic adaptation oftorque to load remains.

If the controlling input signal to such a " final effectorservo-unit " is increasing, its muscle will be shorteningand its tension will increase if opposed-it will be a primemover. If the controlling input signal is constant, themuscle of the final unit will maintain its length stationaryagainst resistance, it will still be a prime mover thoughin a stationary state. Moreover, although the input signalcontrolling length may be constant, the unit will still

develop tension if other movements in which it is notdirectly involved produce purely mechanical tensilestress upon its own muscle, and this muscle is then asynergist. (This view of the inter-relationship of primemovement and synergy is more satisfactory than theone I expressed in my letter of July 3 (p. 40).) If the con-

trolling input signal to the final effector unit is decreasing,the length of its muscle will either increase under load(active lengthening as a prime mover, as when the deltoidlowers the upper limb from the abducted position) or

it will increase without load as movement is reversed

by a reciprocally rising input to opposing prime movers(adaptive lengthening as an " antagonist "). Duringaction as an " antagonist " there is no load on the muscleand therefore the final effector unit does not developany tension.The kind of final neuromuscular effector units described

will therefore allow of smooth and rapid transitionbetween synergic, agonistic, and antagonistic actions ofan individual muscle as these terms are understood inclassical anatomy.

Selly Oak Hospital, I. A. GuEST.Birmingham, 29. 1. A. GUEST.I. A. GUEST.Selly Oak Hospital,Birmingham, 29.

Medicine and the Law

Accident after taking MethylpentynolAN Army officer who was fined t20 by Guildford

magistrates on July 19 for driving a car while underthe influence of drink or drugs was stated to have taken20 capsules of ’ Oblivon ’ during an afternoon.The defendant, who pleaded guilty, said that he left

Donnington, Shropshire, in his car about noon, intendingto drive to Seaford. He was of a nervous temperament,and had cut an article about oblivon from a daily paperand had this with him at the time of his arrest. At

Wolverhampton he bought a half-bottle of gin, and allhe had to eat or drink that afternoon was three-quartersof that. At Oxford he felt rather unsteady and boughta box of 12 oblivon capsules all of which he took. At

Wargrave he bought another box and took 8. He couldremember everything quite clearly until he was goingthrough Guildford but could recall nothing of theaccident.

Police evidence was that the officer’s car slightlytouched " a bus in a narrow street. After the accidenthe was certified bv a doctor as unfit to drive.

Dr. David Haler, giving evidence for the defendant,said that methylpentynol (oblivon) was a new hypnotic

drug which had been credited in the lay press withalmost magical results-results which were not true andshould not have been published in this way. A drugwith such potency should not be available to the publicat large. Taken in large doses, it would accentuate theeffect of alcohol.

ObituaryDAVID McCRAE AITKEN

M.A., M.B. Edin., F.R.C.S., F.R.C.S.E.

Mr. McCrae Aitken, who died at his home in West-morland on July 9, at the age of 77, was long associatedwith the late Sir Robert Jones ; and during the 1914-18war he first made his mark as an outstanding orthopaedicsurgeon in his own right.Born in Singapore in 1876, the son of the Rev. William

Aitken, he was educated in Edinburgh, first at GeorgeWatson’s College and later at the university, where hegraduated M.B. in 1901. Subsequently he became a

fellow of the Royal College of Surgeons of Edinburgh(1904) and of the English college (1908). After holdinghouse-appointments in Edinburgh he went in 1902 toLiverpool, where as house-surgeon to Robert Jones hehad his first encounter with the Liverpool school oforthopaedics. A friend recalls that the young Aitkenat first rebelled at the lively initiative of this group,which contrasted vividly with the rather more austereatmosphere in -Edinburgh, still held in thrall by therepute of its own great men. In later years he wrote(in Frederick Watson’s The Life of Sir Robert Jones) : :

" Such was Lister’s prestige and the tradition that he leftbehind him, that when, in 1897, I entered the Royal Infirmaryin Edinburgh as a student, the first operations I saw werethree consecutive operations on cases of tuberculous knee

joints of differing severity. All the cases were put to bedin wooden knee splints, which had to be removed for dressing.In all cases wound healing was uneventful-the antiseptictradition so far was perfectly sound-but there was no

continuous rest in plaster or anything like a Thomas’s kneesplint, and before I left Edinburgh in 1902 I saw each of thosethree limbs amputated above the knee."

In 1904 he returned to Edinburgh for a spell; butthe following year he came to London, where between1905 and 1908 he worked at the Bolingbroke Hospital,eventually as medical superintendent. Thereafterhe was appointed assistant surgeon to St. Vincent’sSurgical Home for Cripples (as the hospital was thencalled). It was during and after the war of 1914-18 thatMcCrae Aitken came to the fore, as surgeon to theMilitary Hospital, Shepherd’s Bush, and to the RobertJones and Agnes Hunt Orthopaedic Hospital, Oswestry,where he succeeded Sir Robert Jones as the acknowledgedleader.

His devotion to the Liverpool school was shown byhis book on Hugh Owen Thomas: : His Principles andPractice (1935). Early in his career he was impressedby the value of rest in orthopaedic practice-a valuethat he emphasised in addressing the Medical Societyof London on his war-time experiences (Lancet, 1917.i, 10), and to which he again referred in his Hugh OwenThomas lecture in Liverpool in 1931, when he spoke onRest and Movement in the Treatment of Lesions ofJoints.Throughout his life he fought against indifferent

health, and in the early ’20s he had to abandon hiswork for some months ; his years of retirement weremarred by illness.H. P. writes : e " McCrae Aitken had become a name

only to the younger generation of British orthopaedicsurgeons, for since the last war his frail health had madeit impossible for him to emerge from his retirement inWestmorland to attend meetings of the British Ortho-paedic Association. His whole career was a notableexample of a courageous battle against the physicalhandicap of a severe respiratory disability. This mani-fested itself in recurring uncontrollable bouts of coughingwhich came on often without warning during the workingday. To his colleagues and assistants these attackswere distressing to behold ; and there is no doubt that