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PHILOSOPHICAL TRANSACT EONS 
 
 or THE 
 
 ROYAL SOCIETY OF LONDON. 
 
 Series B. 
 
 VOL. 
 
 188 (1897), 
 [Plates 4 
 
 pp. 
 
 =-9.] 
 
 257- 
 
 -299 
 
 oisr ' 
 
 THE REGENERATION OT NERVES. 
 
 ROBEET KENNEDY, M.A, B.Sc, M.D., Glasgow. 
 
 LONDON : 
 
 PUBLISHED FOE THE ROYAL SOCIETY 
 
 BY DULAU AND CO., 37, SOHO SQUAEE, W. 
 
 CONTINENTAL AGENTS, MESSRS. FRIEDLANDER AND SON, BERLIN. 
 
 1897. 
 
 B. 148. <P 28.8.97, 
 
 Price Three Shillin(]S and Sixpence. 
 
 
ISl Cf * 'loo 
 
 1 
 
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y 
 
 [ 257 ] 
 jVo- 2 06*? 
 
 VIII. On tlie Reyeneration of Nerves. 
 
 By EoBEBT Kennedy, M.A., B.Sc, M.D., (^hisyon: 
 
 Communicated by Professor McKendrick. 
 
 iFio.ii the Western Infinaayy, Glusyi.ir, avd the Znoloyiedl Lahnratory of the Vnicerslty of Qlaagoiu. 
 Received Jannaiy 7,— Read February 1], 1897. 
 
 [Plates 4-9. J 
 
 Contents. 
 
 Page 
 
 T. Historical I nti-od action 258 
 
 II. Cases of Secondary Suture of Jierves 262 
 
 1. Of median and ulnar six-and-a-half months after division 262 
 
 2. Of median tliree months after division 265 
 
 3. Of median and muscnlo-spiral several weeks after interruption at seat 
 
 of fracture of humerus 267 
 
 4. Of ulnar eighteen months after division 269 
 
 III. Deductions from results of operation ... . . . 271 
 
 IV. Microscopical examination of the portions removed previous to suture .... 274 
 
 1. Methods 274 
 
 2. Microscopical appearances 274 
 
 a. Central ends . . . 275 
 
 h. Peripheral ends ... .... 276 
 
 c. Intercalary cicatricial segments . . . . . ... 277 
 
 d. Portions compressed at seat of fracture . ' . . . . 278 
 
 V. Deductions from the microscopical appeai'ancos 280 
 
 1. Degeneration 280 
 
 2. Regeneration of nerve fibres in the peripheral segment, while still sepa- 
 
 rated from the central segment 282 
 
 3. The origin of the young fibres 283 
 
 4. Characters of the young fibres 285 
 
 5. Cicatricial intercalary segments 286 
 
 VI. General Conclusions 287 
 
 VII. Bibliography 287 
 
 VIII. Explanation of Plates 297 
 
 MDCCOXCVir. — B. 2 L 28.8.97 
 
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258 DR. R. KENNEDY ON THE REGENERATION OP NERVES. 
 
 I. — Historical Introduction. 
 
 The view expressed by Galen that nerves once divided are incapable of undergoing 
 repair, was that universally accepted until the latter part of last century. It is 
 true that Guy de Chauliac* speaks of the perfect restoration of divided nerves, but 
 as he speaks at once of nerves and tendons, it is doubtful whether we can accept his 
 remarks as really referring to nerves. 
 
 Cruikshank (2) was the first to show that reunion is possible. He divided the 
 vagus of the right side in a dog, and three weeks later excised a portion from the 
 nerve of the opposite side, and the animal made a perfect recovery. Three weeks 
 later he killed the dog, and found both nerves reunited. The results of his investi- 
 gations were communicated to the Royal Society on 13th June, 1776, but his paper 
 was not printed until nineteen years later. His preparation, however, was placed in 
 Wm. Hunter's Museum, and was the means of stimulating others to further researches. 
 I found this preparation in the Museum in Glasgow University, and was easily able 
 to identify it from the drawing published with the paper.t 
 
 Cruikshank himself held on physiological grounds that the nerves in his prepara- 
 tion were united by nerve substance, but the prevailing opinion was that the bond of 
 union was composed of connective tissue. Fontana (3), Michaelis, Haighton (6), 
 Meyer (7), and Prevost (10), supported the former view, on the ground of their 
 own researches, while Monro (4), Arnemann (5), and others held to the latter view. 
 The work of Steinrijck (14) which appeared in 1838, set the matter at rest, for 
 from that time the possibility of reunion of nerves by nerve substance is admitted by 
 almost aU observers. 
 
 With Nasse (15) a new field of investigation was begun, for that observer 
 discovered that after section of a nerve, degeneration of the primitive fibres occurs. 
 He, however, only examined the seat of section, as also did Gunther and Schon (16) 
 in the following year, and Stannius (18) a few years later, while he observed on one 
 occasion degeneration of the ultimate ramifications of the nerve in the muscular fibres 
 after section of the stem, did not follow up the clue, but left to Waller (20, 22 to 
 29) the discovery of the inevitable degeneration of the whole peripheral segment after 
 section of a nerve, and the enunciation of the law of dependence of the nerves for 
 their nutrition on trophic centres. Waller's view is that after section of a nerve, the 
 whole nerve fibre is destroyed, and that it never can recover its structural characters 
 or functional properties, and that the young nerve fibres are new formed structui-es 
 
 * GuiDO DE Cauliaco (1), p. 114, "Ego vidi efc audivi in multis nervos et thenanton incisos ; et eos 
 itii restauratos cum sutura efc aliis ausiliis, quod erat postea incredibile ipsos fuisse incisos." 
 
 The numbers in parenthesis refer to the Bibliography, p. 287. 
 
 t Mjr thanks are due to Professor Toung for granting every facility for and help in identifying 
 this preparation. The delay in printing Cruikshask's communication until after the death of Hunter 
 accounts for the history of the preparation not having been inserted in the Catalogue of the Museum. 
 
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DR. H. KENNEDY ON THE REGENERATION OF NERVES. 259 
 
 always found lying between the old degenerated remains ; that they are never found 
 till reunion has occux'red ; and that they start in the intermediary uniting segment, 
 and travel on to the ultimate ramifications of the nerve. 
 
 This view was widely acce})ted, but the length of time re(|uire(l for such a process of 
 regeneration was found not to accord with clinical observations made by Paget (30), 
 and experimental observations by Schiff (31) and by Bjruch (32), and these observers 
 held that nerves must also be capable of undergoing I'epnir by first intention, to 
 n.ccount for the rapid return of function, M'hich they found alter certain cases of 
 nerve section. 
 
 The view advanced by Waller that the peripheral segment of a divided nerve 
 is incapable of being regenerated, until reunited to the central segment, had been 
 received without contradiction. Philipeaux and Vulpian (38, 39), however, while 
 corroborating the ultimate degeneration as a result of separation of a nerve from its 
 centres, found that the peripheral segment can, even while remaining separate from 
 the central segment, undergo reparation. Not only so, but a portion of the lingual 
 nerve transplanted under the skin of the inguinal region in dogs contained new fibres 
 after six months (47). These observers held that the axis-cylinder was not destroyed 
 during degeneration, and that restitution consisted simply in a reaccumulation of the 
 myeline, and that, therefore, restitution was simply a restoration. Their results were 
 met by much opposition, Schiff (41), Landby (42), and Ambhosoli (43) writing at 
 the time in opposition to them, and since, almost all the writers have opposed 
 their conclusions, some maintaining with Ranvier (102) that the regeneration which 
 they observed was due to connecting strands of tissue between the proximal and 
 distal ends, strands which they had failed to observe, and even Yctlpian (77 , 86) 
 himself, some years later, withdrew from his former position, admitted that Avhat had 
 been seen were not regenerated fibres, and denied the possibility of autogenetic 
 regeneration of nerves. Their conclusions, however, are supported by Mitchell (80), 
 and more recently by Bowlby (146). 
 
 Tiie general opinion was against the possibiiity of reunion of nerves by first 
 intention, when in 1864 the cases of nerve suture in man by Nelaton (54), and 
 Laugier (55) were published. In Niiilaton's case a neuroma was excised from the 
 median in the arm, and return of function was established in a few days, and in 
 Laugier's case the median was completely divided in the forearm, was sutured, and 
 function returned in a few days. 
 
 The interest in the subject of nerve regeneration was greatly increased by the 
 publication of these cases, and several workers were induced to commence experi- 
 mental research to investigate the matter. Eulenburg and Landois (56, 60), from 
 their investigations in animals, strongly opposed the view that nerves could heal by 
 first intention, and thought the employment of suture a highly dangerous proceeding. 
 Magnien (61), on the other hand, found no harm from the employment of suture, and 
 
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260 DR. R, KENNEDY ON THE REGENERATION OF NERVES. 
 
 in two cats he found return of function in a few days after section and employment 
 of suture. 
 
 Further doubt was thrown on the value of the clinical experience of early return 
 of- function after nerve suture, by the experiences of Hichet (62) and of LsTliiVANT 
 (73,, 82). RccHET observed a case in which, after section of the median nerve, sensa- 
 tion remained in the distribution of that nerve ; and Arloing and Tripier (70) 
 explained the case by showing that in the dog there is in the skin an anastomosing 
 network of the ultimate fibrils of all the nerves supplying the paw, and that no part 
 of the skin is exclusively supplied by a single nerve. Lbttevant, again, found that 
 after section of the median nerve Avithout reunion, movements were developed in the 
 hand which resembled those performed by the muscles supplied by the divided nerve, 
 and showed that these movements were imitations by neighbouring muscles, whose 
 supply remained intact, of the movements performed by the paralysed, muscles. He 
 also shov/ed that, though the sensory supply of a region is cut off, sense of touch may 
 remain by mediate communication with other nerves. Tillmanns (123), again, 
 supposes that from neighbouring intact nerves, filaments may grow out into the 
 angesthetic region ; and Remak (87), that anastomosing fibres may develop after nerve 
 section, in a way comparable to the development of the collateral circulation after 
 occlusion of an artery. 
 
 Thus the clinical experience of early return of sensation after nerve section has been 
 discredited as a proof of the reunion of the nerve. Vanlair (1-22), for example, con- 
 siders that if after nerve section sensation returns in a very short time, it is due to 
 anastomosing fibres, and the short period of anaesthesia is due to the numbing effects 
 of haemorrhage ; if more slowly, that it is due to supplementary supply ; and that if a 
 very long time elapses, then it is due to regeneration of the divided nerve. 
 
 But the cases of secondary suture published speak strongly against the slow 
 process of regeneration from the central end. One of the first of these was a case 
 published by Jessop (75), where the ulnar nerve had been cut across above the winst 
 nine years before the operation of suture. Before the operation there was total loss 
 (.)f sensation and motion in the region supplied by the ulnar. The hand was thin and 
 the palm hollowed out. The cicatrix uniting the ends was excised and the nerve 
 sutured, and eiglit days after the operation sensation began to return, and in eight 
 days more had returned everywhere, except at the tips of the fingers. A similar case 
 v.as published by Langenbeck.* In his case the sciatic had been cut across two and 
 a half 3-ears before the operation, and there was total anaesthesia, and yet sensation 
 began to return three days after the operation. Also (.)gston (120) performed 
 secondary sutui-e of the ulnar in a case in which the nerve had been cut long enough 
 to produce the characteristic atrophy and claw-hand, and in which there was total 
 loss of sensation and motion, and yet, a week after the operation, the return of 
 sensation was determined, 
 
 * After WoLBEUG (127), p. 341. 
 
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PR. E. KENNEDY ON THE REGENERATION OP NERVES. 261 
 
 These and similar cases in which sensation remains totally lost before operation 
 and long after the date of section of the nerve, but returns in a few days after the 
 operation, cannot be explained on the theories mentioned, and must indicate a 
 reunion of the nerve, and re-establishment of conductivity ; and these cases would 
 indicate that nerves, though long divided, must be capable of very early reunion, 
 when placed in suitable conditions for that to take place. 
 
 At present the views of the histological process of regeneration are divisible into 
 two groups : — 
 
 1st. The view established by Ranviek (81,10'2), and closely coinciding with that 
 of Waller, that the periphei'al segment of the nerve takes no part in the process of 
 regeneration, but that the latter is effected entirely by growth of new axis-cylinders 
 from those of the central end of the nerve, the peripheral segment acting merely as 
 a guide for growth to the end organs. This view is very widely accepted, and is 
 supported by the histogenetic researches of Kollikbr (109) and His (ill, 144, 147). 
 It has been recently supported by Howell and Huber (15G), Stroebe (158), and 
 NoTTHAFFT (159), who, however, find that the envelopes of the axis-cylinders are 
 supplied from elements in the peripheral segment. 
 
 2nd. The view that the new fibres are derived from elements in the distal segment, 
 and that the young fibres thus formed become attached to the fibres of the central 
 segment, and thus restore conductivity. Recently Bungner (150) has adopted this 
 view, and holds that the young fibres are derived from the protoplasm and nuclei of 
 the interannular segments. These form spindle-cells which unite end to end, and 
 form protoplasmic threads, which soon shovv^ longitudinal striation, the beginning of 
 the axis-cylinder. The new myeline sheath is formed from the outer layer of the 
 young fibres, and also partly by absorption of the old myeline. The old sheath of 
 Schwann disappears, and the new is derived from the endoneurial tissue. The 
 nuclei of the new sheath of Schwann, are the direct descendants of the nuclei of 
 the old, and have clearly the value of neuroblasts. This view coincides with the 
 histogenetic researches of Balfour (93, 121) and Milnes Marshall (97). 
 
 According to the first view, the process of regeneration requires for its accomplish- 
 ment a more or less long period of time, depending on the length of the peripheral 
 segment. Thus Vanlair (160) estimates the rate of growth from the central end to 
 be from 0'3 millim. to 1 milHm. daily, after section and immediate perfect coaptation. 
 According to the second view, the time is not necessarily long, seeing that the 
 material for the work of regeneration is already laid down along the whole length of 
 the peripheral segment. Thus the published cases of secondary suture, with speedy 
 return of sensation, are enigmatical on the first view, but are capable of explanation 
 on the second view. 
 
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262 Tin. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 II. — Cases op Secondaey Sutore of Nerves. 
 
 My obsei'vatioiis were made on four cases,* in three of which the nerves had been 
 accidentally divided some time previously, and functional reunion had not occurred ; 
 while in one the nerves were functionally interrupted by compression at the seat of a 
 fracture. The cases were as follows : — 
 
 Case I. — Division of the ulnar and median nerves in the forearm. 
 
 Case II. — Division of the median nerve in the forearm. 
 
 Case III. — Interruption of the median, ulnar, and musculo-spiral nerves, resulting 
 from a fracture at the elbow joint. 
 
 Case IV. — Division of the ulnar nerve in the forearm. 
 
 These cases, therefore, presented seven injured nerves. In the cases of division^ I 
 performed the operation of secondary suture, and in that of compression at the seat 
 of fracture, dissected the nerves from their adhesions, and removed the compressed 
 portions from the median and musculo-spiral, and sutured. In every case the 
 portions removed were preserved for microscopical study. 
 
 Case I. (Plate 4, figs. 1 and 2.) 
 
 A boy, aged 16 years, received a wound with a piece of glass, on the front of the 
 right forearm in its middle third. The wound was deep, and bled freely. It A\as 
 sutured, and healed in about eight weeks, but by that time it was apparent that 
 damage had been done to the nerves, as the hand was paralysed and sensation lost. 
 Soon atrophy manifested itself, and the boy was unable to return to his work. He 
 came for advice on .3rd March, 1894, fully six months after the accident, and his 
 condition was found to be as follows : — 
 
 A cicatrix, 13 centims. in length, extended across the middle third of the front of 
 the right forearm, obliquely from above downwards and inwards, crossing almost the 
 entire breadth of the forearm. The lower and inner third of this cicatrix was red, 
 and painful when firmly pressed ; the middle third was extremely red, and prominent 
 at its junction with the inner third, and its surface was thin and very tender even to 
 the slightest touch ; the upper and outer third had the appearance of an ordinary 
 cicatrix. On moving the fingers, the cicatrix was found adherent to the muscles. 
 The muscles of the forearm were atrophied, the right forearm being everywhere about 
 1 centim, less in circumference than the left at corresponding levels. 
 
 The trophic changes in the hand were well established. The skin was smooth 
 red, and shining, and the flexures but little marked. There was a raw surface 
 without signs of heahng, on the inner side of the first internode of the fifth digit ; 
 
 * I owe to De. Paxteeson my sincere thanks for permission to perform these operations in his ward 
 in the Western Infirmary, Glasgow, and also for valued suggestions thereon. 
 
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DR. R. KENNEDY ON THE REGElVERATION OF NERVES. 263 
 
 this was the result of a burn received two weeks previously. The nails had a 
 corrugated surface. The hand was colder than the left. Tlieni was great atrophy 
 of the small muscles, the palm being hollowed out and tlie thenar and hypothenar 
 eminences replaced by hollows. 
 
 The attitude and movements of the hand were those characteristic of section of 
 the median and ulnar nerves. Thus all the fingers were held flexed at the two 
 interphalangeal, and overextended at the metacarpo-phalangeal joints. The fingers 
 could be |ias;sively extended, but voluntarily only to a slight extent, and in both 
 cases only with accompanying flexion of the hand at the wrist. The hand was 
 carried semiflexed at the wrist, simulating wrist -drop, but could be voluntarily 
 straightened, although it could not long be held in that position, as a painful feeling 
 was soon developed. He could also perform lateral movements of the hand at the 
 wrist. The hand could only be partially closed, and v/hen he attempted to extend 
 his fingers keeping the wrist straiglit, only the first phalanges responded, the two 
 distal remaining flexed. The itiovements of adduction and opposition of the thumb, 
 and abduction of the fingers were impossible. With the hand dynamouieter, he 
 registered with the right hand 4 kilos., and with the left IG kilos. The small 
 muscles of the hand tested electrically gave no response to the faradic current, but 
 responded to the galvanic current. 
 
 The condition of sensation was as follows. There was pain elicited by pressure 
 over the terminal phalanx of the thumb ; absolute anaesthesia, even for touch, in 
 every part of the fifth and fourth digits ; very slight sensation, but none for pain, as 
 tested by pricking the skin with a pin, on the third digit and palmar aspects of the 
 second and first ; total angesthesia of the palm and of the ulnar side of the dorsum of 
 the hand ; and normal sensation on the radial side of the dorsum of the hand, and 
 over the thenar eminence and dorsal aspects of the first and second digits. 
 
 On 15th March, 1894, exactly six and a half months after the accident, I per- 
 formed the operation of secondary sutui'e. The median nerve was laid bare at the 
 seat of section, and the two ends of the nerve were found united by a dense 
 cicatricial mass, somewhat thicker than the nerve, and about 1'5 centim. in length. 
 This cicatricial mass lay under the middle third of the skin cicatrix, which was 
 found at the examination to be so very tender. The nerve itself was much thicker 
 than a normal median nerve. 
 
 The ulnar nerve was next exposed through the same incision. It was found 
 similarly hypertrophied, but the ends were separated about 2 centims. The central 
 end lay about the level of the tender inner and lower third of the cutaneous cicatrix, 
 and presented a hard bulb measuring about 1"5 centim. in length and 1 centim. in 
 transverse diameter. The peripheral end lay at a lower level than the cicatrix in 
 the skin, was not so much hypertrophied, and presented a bulb about half the size 
 of that on the central end. It lay surrounded by loose connective tissue. 
 
 The cicatrix on the median was excised at its junction with the ends of the nerve, 
 
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264 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 and while the surface exposed at the central end showed nerve substance, that on 
 the peripheral presented a homogeneous aspect. On removing an additional slice 
 from the latter, nerve substance was exposed, and the section presented an appear- 
 ance similar to that of the central end. The bulb on the central end of the ulnar 
 was then cut off, and then the smaller bulb from the peripheral end, the sections in 
 both cases exposing nerve tissue. Two sutures of chromic catgut were passed 
 through each of the nerve ends by means of a flat needle, the plane of the needle 
 being kept parallel to the course of the nerve fibres in order to inflict as little damage 
 as possible. The hand and forearm were then fully flexed, and the sutures tied. 
 The median came together easily, but the ulnar ends could not be brought together 
 nearer than about 6 millims. The forearm and hand were then fixed fully flexed 
 in a splint. 
 
 Three days after the operation, the first sign of returning sensation appeared ; for 
 on pinching the tip of the little finger, while the patient's head was covered, he cried 
 out with pain. On the following day, he recognised the little finger when touched, 
 and felt pain when it was firmly grasped or pricked with a pin. On the ninth day, 
 the wound was dressed for the fii'st time, and the patient stated that he felt his hand 
 much stronger than before the operation. The improvement in sensation was main- 
 tained. On the nineteenth day, relaxation of the extreme flexion was begun 
 gradually, and a more careful examination made of the condition of sensation. It 
 was then found that he localised correctly all parts of the fingers touched, unless 
 when the touches were slight, when he occasionally mistook the finger touched, and 
 occasionally failed to feel a gentle touch on the little finger. The sore on the first 
 internode of the little finger was now quite healed, and the operation wound was 
 healed, except at the extreme ends, through which drainage had been made. Towards 
 the end of the first month, the sensation had still further improved ; for now he 
 located correctly the gentlest touches, and responded quicker than he did at first. 
 The limb had now been gradually extended, and the fingers, also, had now been fully 
 extended by firm bandaging to the splint. He could also at this time partially close 
 and again open the hand. Electrical treatment of the hand was then commenced. 
 With the positive pole applied above the wrist over the respective nerves, and the 
 negative to Ziemssen's points over the small muscles, there were no contractions with 
 the faradic current, but with a moderate galvanic current there were distinct contrac- 
 tions of the small muscles of the thumb ; but only very slight contractions could be 
 detected in the other small muscles. By a month and a half from the date of opera- 
 tion, the electrical condition had improved ; for now, while all the small muscles 
 responded to the galvanic current, the small muscles of the thumb gave contractions 
 with the faradic current. There was also a notable return of power in the hand, as 
 his grasp was appreciable. He was able to write legibly, which he was quite unable 
 to do before the operation. By two months, the appearance of the skin had improved, 
 and he was able to open and close the hand ; but beyond a slight degree he could not 
 
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DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 265 
 
 oppose the thumb. The cicatrix of the original wound, which was so red and tender 
 before the operation, had now the appearance of an ordinary cicatrix, and had lost its 
 tenderness. In the fifth month, he stated that he found no difference in sensation 
 between the two hands, and that the hand was useful, although he was still unable 
 to perform the more delicate movements ; and this was explained by the persistent 
 weakness of the opponens pollicis muscle. Despite the improvement in power, the 
 atrophy of the palm and of the thenar and hypothenar eminences was still distinct, 
 though less. The patient was last seen seven months after the operation, and at that 
 time the improvement in sensation and motion was maintained, and the grasp of the 
 hand much stronger. The sensation of the hand was perfect, and the appearance of 
 the skin much improved ; but there was still marked atrophy of the small muscles. 
 The improvement in grasp up to that time is shown in the following table, taken witl 
 the hand dynamometer: — 
 
 Date. 
 
 
 Right. 
 
 Left. 
 
 March 3 . . . 
 
 „ 15 . . . 
 
 May 1 . . . . 
 
 Before operation 
 Operation 
 
 kilos. 
 
 4 
 
 2 
 4 
 7 
 8 
 14 
 
 kilos. 
 16 
 
 16 
 29 
 
 „ 8 . . . . 
 
 
 „ 16 ... 
 
 
 June 21 . 
 
 
 October 19 . . 
 
 
 
 
 Case II. 
 
 A man, 37 years of age, a carpenter, on 20th November, 1894, received a deej 
 wound with a chisel on the right forearm, transversely, just above the wrist in front 
 The wound was not stitched, and was said to have healed in about a fortnight with- 
 out suppuration. Immediately after the accident he noticed loss of sensation in the 
 thumb and index and middle fingers. Sensation did not return, and the hand being 
 useless, he sought advice on 28th February, 1895. His condition then, three monthi 
 and eight days after the accident, was as follows : — 
 
 On the right forearm there was a linear cicatrix, 2"5 centims. in length, situateci 
 transversely above the wrist in front. Through this cicatrix a dense oval swelling, 
 about the size of an almond, could be felt in the middle line of the forearm, and on 
 applying pressure a tingling sensation shot up the arm and down into the hand. The 
 skin, especially of the front of the index finger, thumb, and outer half of the palm, 
 was smoother than is natural, and the flexures were greatly diminished. There was 
 marked atrophy of the thenar eminence. The index and middle fingers could not be 
 fully extended, nor could they be brought into contact with the palm ; and there was 
 considerable loss of power of flexion of the thumb, and the movement of opposition 
 was impossible, 
 
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266 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 The condition of sensation was the following : — Total ansesthesia on the anterior 
 aspects of the thumb, index, and middle fingers, and on the outer half of the palm ; 
 only obtuse tactile sensation on the outer side of the ring finger and over the thenar 
 eminence. On pricking with a pin the palmar surfaces of the thumb, index, middle, 
 and outer half of the ring fingers, no pain or other sensation was felt. 
 
 On 28th February, 1895, the median nerve was exposed by a longitudinal incision, 
 5 centims. in length, over the seat of injury. The nerve was found hypertrophied, 
 and the ends united by a dense mass of cicatricial tissue, about 2 centims. in length 
 and 1"5 centim. in greatest breadth, but flattened antero-posteriorly. This mass was 
 excised at its junction with the nerve, and the sections exposed at the ends of the 
 nerve showed points of what appeared to be nerve substance, but these were 
 separated by dense white tissue. Two sutures of chromic catgut were passed through 
 the whole thickness of the nerve, and the ends drawn together, and this was easily 
 effected when the hand was fully flexed. The wound was closed, and no drainage 
 used, and the limb bandaged to a splint with the hand fully flexed. 
 
 Two days after the operation sensation commenced to return. The sense of 
 touch was present on the palmar aspects of the fingers and thumb, and a pin thrust 
 into the palmar aspect of the thumb was felt as a painful sensation ; but sensation 
 was still vague. By the ninth day sensation was much improved, and by the 
 thirteenth day pain was felt from the prick of a pm in the palmar aspects of all the 
 affected fingers and in the thumb, and by the seventeenth day there was still further 
 improvement. From this time the hand was gradually relaxed, and, finally, about 
 the fourth week, when got into the extended position, the splint was discarded. A 
 fortnight later there was distinct impiovement in the muscular power of the hand. 
 Towards the end of the second month (24th May) his sensation had further improved, 
 and both touch and sense of pain were quite distinct, although not yet felt by 
 the patient so distinct as in the other hand, but the point of the index finger was 
 not so sensitive as the other parts of the median distribution. The improvement in 
 the muscles was very decided ; for not only had the atrophy of the thenar eminence 
 in great part disappeared, but the movement of opposition was now so well 
 developed that he was able to touch the tip of the middle finger with the tip of the 
 thumb. At the end of six months, there was still further progress. Localisation of 
 touch was perfect for all the parts concerned, and there was much improvement in 
 the sensation of the last phalanx of the index finger ; but even yet the patient found 
 sensation less acute than in the sound hand. The grasp was almost as good as that 
 of the left hand, and the movement of opposition was still further improved, since 
 now he could touch with the thumb the tip of the ring finger. "What prevented 
 him from having as perfect use of his hand as formerly, was his inability to flex 
 completely the terminal phalanges of the index and middle fingers. Thus, when he 
 closed his hand, the tips of these fingers did not come sufficiently into the centre of 
 the palm to enable him to grasp firmly smaller objects ; but for larger objects his 
 
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DB.. R. KENNEDY ON THE REGENERATION OF NERVES. 267 
 
 grasp was as firm as that of any average hand. He had already some time since 
 returned to his work, being able to use his hand. At the end of nine months the 
 condition was further improved. He could distinguish with each finger the differ- 
 ence between the smooth and rough side of sand-paper. The atrophy of the thenar 
 eminence had not only disappeared, but the eminence was even slightly greater 
 than that of the left hand, and he was able to pick up the smallest piece of paper 
 between fingers and thumb, although at six months he could only pick up a coin. 
 At the end of a year, there was still further improvement, as he could now oppose 
 the thumb to the little finger, but the grasp for smaller objects was still defective 
 from his inability to flex completely the terminal phalanges of the index and middle 
 fingers, although it was better than at nine mouths. His sensations of touch, pain, 
 and thermic difference were correct, although not felt quite so clearly as in the left 
 hand. As showing the degree to which the grasp had improved compared with 
 that of the left hand, the dynanometer reading is of importance. One year and 
 four months after the operation, with the right hand he registered 54 kilos., and 
 with the left 58 kilos. (Plate 5, figs. 1 and 2.) 
 
 Case III. (Plate 6, figs. 1 and 2.) 
 
 A girl, aged 6 years, sustained a fracture of the left elbow joint from a fall. The 
 limb was fixed in splints, which were removed at the end of four weeks. Her hand 
 was then found to be anaesthetic and paralysed. On 12th December, 1895, eight 
 weeks after the accident, I first saw her, and found her condition to be as follows : — 
 
 The internal condyle at the elbow joint was thickened, but otherwise the appear- 
 ance of the joint was normal. The joint, however, only permitted a slight range of 
 voluntary movement, and even under chloroform this range could not be much 
 increased on forcible passive movement. The child carried the forearm flexed at a 
 right angle, and the supinator longus was felt firmly contracted. Supination and 
 pronation could not be voluntarily performed, but were easily accomplished passively. 
 The hand was carried flexed, and could not be straightened, its range of movement 
 being very limited. Voluntary motion was abolished. The first phalanges of the 
 fingers were extended ; the second and terminal, flexed. The first phalanx of the 
 thumb was extended ; the terminal, flexed. By passive movement the two distal 
 phalanges of the fingers could be extended, only when the first were flexed. The 
 forearm was wasted only to a degree appreciable by measurement ; but the hand 
 showed distinct trophic changes. Thus the dorsum was imnaturally smooth and 
 wasted, and on the palmar aspect, and especially at the tips of the fingers, the skin 
 was smooth and glossy, and on the palm the flexures were very indistinct. The 
 small muscles were atrophied, giving a scooped-out palm, and hollows in place of the 
 thenar and hypothenar eminences. Voluntary movement of the fingers was scarcely 
 appreciable, but the slightest degree of flexion and extension could be detected. 
 
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268 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 With the faradic current the muscles of the forearm and hand gave no response ; 
 but with the galvanic, good contractions. Sensation in the forearm was normal ; but 
 neither touch nor the prick of a pin could be felt in any part of the hand, except over 
 the outside of the first metacarpal bone, extending over the thenar eminence for a 
 short distance in a less distinct degree. 
 
 On 13th December, 1895, the musculo-spu-al nerve was exposed by an incision 
 about 9 centims. in length, crossing the bend of the elbow. The nerve exposed to view 
 was much thickened, and, a little below the bend of the elbow, where it divides into 
 radial and posterior interosseous, it was firmly bound down by, and adherent to 
 cicatricial tissue. This nerve exposed, the wound was temporarily closed, and the 
 Ibow joint then excised through a single incision behind. The ulnar nerve was next 
 I aid bare from the deep surface of the internal flap. The ulnar was also considerably 
 bypertrophied, and firmly adherent at the level of the joint. It was freed from its 
 idhesions. The median nerve was then exposed by an incision in front. It also was 
 lypertrophied, and firmly adherent to the surrounding cicatricial tissue. It was 
 lissected from its adhesions, but these being very intimate, the portion which seemed 
 to be most involved was excised, that portion measuring about 12 millims. in length. 
 The ends were then brought into apposition, which was easily effected after the 
 excision of the elbow joint, and sutured with two chromic catgut sutures, passed 
 through the whole thickness of the nerve. The musculo-spiral was then dissected 
 from its adhesions, and as these were very intimate at its point of bifurcation into 
 its two branches, the radial was divided about 6 millims. from its origin and the 
 posterior interosseous about 3 millims. from its origin. The terminal portion of the 
 musculo-spiral was then removed about 12 millims. from its bifurcation, and the two 
 peripheral ends united to the central end of the musculo-spiral with chromic catgut. 
 The wounds were then washed and sutured and drained with catgut. The limb was 
 then fixed in a splint with the forearm semi-bent. 
 
 The dorsum of the hand, the only part exposed, was tested daily for the first sio-n 
 of returning sensation ; but there was no change till the fourth morning after the 
 operation, when there was an indication of improvement, in so far that some 
 sensation, produced by pricking with a pin, was found extending downwards from 
 the wrist, but only for a short distance. There was no further change till the 
 seventh day, when the sensation had travelled down to the level of the mid- 
 transverse line on the dorsum of the hand. There was also a point on the inside 
 which was sensitive. On the following day there was sensation on the inside as far 
 as the head of the metacarpal bone, and also a further extension on the outside. 
 Pricking the skin of the palm with a pin caused the child to cry with pain. On the 
 ninth day the same conditions obtained, but the child could as a rule locate the 
 region pricked, but occasionally made a mistake. On the eleventh day there was 
 obscure sensation in the fingers. The improvement continued, and on the seventeenth 
 day the wounds were dressed and found healed, except at the points where they had 
 
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DR. R. KENNEDY ON THE REGENERATION OF NERVES. 269 
 
 been drained. The arm was put on a rectangular splint, and the fingers bandaged 
 out straight. The sensation had now so far improved, that the child could locate 
 the finger pinched, although occasionally she made a mistake. At the end of six 
 weeks, the last occasion upon which the patient was seen, the sense of pain on being 
 pricked with a pin had returned in the little finger, and was quite distinct in the 
 palm, but the other regions of the hand were still insensitive to pain. There was no 
 return of motion, and the electrical reactions remained as before the operation. 
 
 Case IV. (Plate 5, fig. 3.) 
 
 A woman, aged 29 years, sustained a cut with a piece of glass on the right 
 forearm, about 2*5 centims. above the wrist, extending from the front round the 
 inside. The wound was stitched and healed without trouble, but she soon discovered 
 that she had lost sensation in the little and ring fingers. Shortly afterwards the 
 little and ring fingers and the palm of the hand began to waste, and the skin to 
 assume a smooth glossy appearance. I saw her for the first time on 23rd January, 
 1896, eighteen months after the accident, when she presented the following 
 condition : — 
 
 The position of the wound was marked by a linear cicatrix on the right forearm 
 commencing near the middle line in front, 2*5 centims. above the wrist, and extending 
 in\^•ards to the ulnar side, curving upwards in its course. The cicatrix was not 
 tender, but when firmly pressed, a tingling sensation was sent up the arm and down 
 into the hand. The little and ring fingers were over-extended at the metacarpo- 
 phalangeal joints, and semi-flexed at the first and second interphalangeal joints. 
 Both fingers were smooth and glossy, the ring finger showing these characters more 
 so on its inner side. The inner half or three-quarters of the palm had a similar 
 shining appearance, and the flexures had almost disappeared. The nail of the little 
 finger was rough and irregularly grown. The joints of the two afiected fingers were 
 stiff", and allowed only a limited range of movement either voluntary or passive. The 
 two inner fingers could not be brought into contact with the palm, when she 
 attempted to firmly close the hand. There was both on the little finger and inside 
 of the ring finger, and on the inner half of the palm some slight sensation, but it was 
 of an abnormal character. When touched these parts could be obtusely distinguished, 
 but when pricked with a pin there was no sense of pain. The other parts of the 
 hand were normal. 
 
 On 24th January, 1896, the ulnar nerve was laid bare by an incision extending 
 upwards from the pisiform bone about 7 centims. The tendon of the flexor carpi 
 ulnaris was found lying un-united, having been divided at the time of the accident 
 along with the nerve. Both the central and peripheral segments of the ulnar nerve 
 were abnormally thick. The proximal segment of the nerve ended in a hard bulb, about 
 the size of a small hazel nut, which was adherent to the tissue around. This bulb 
 terminated in a tapering strand of tissue, which, however, had no apparent connexion 
 
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 270 DR. E. KENNEDY ON THE REGENERATION OF NERVES. 
 
 with the distal segment of the nerve. The peripheral segment of the nerve extended 
 upwards behind the central bulb for a short distance, and was very firmly bound 
 down to the deeper tissues by cicatricial bands. There was no bulb upon this, but 
 it presented a conical ending, terminating also in a strand of tissue, which had no 
 apparent connexion with the central segment. The bulb was cut off from the central 
 segment, and about 4 millims., including the conical ending, removed from the 
 peripheral segment, and in both cases the exposed sections displayed the appearance 
 of nerve tissue. The nerve was then sutured with chromic catgut, passed through 
 the Avhole thickness, and, after the tendon of the flexor carpi ulnaris had been 
 repaired, the wound was closed, no drainage being used. The arm was bandaged to 
 a splint, with the hand fully flexed. 
 
 Three days after the operation there was distinct sense of touch on the inside of 
 the ring finger, but none, not even the obtuse sensation present before the operation, 
 on the httle finger. Five days after the operation the patient cried out when the 
 inside of the ring finger, or either the back or fiont of the little finger, was pricked 
 with a pin, although her head was covered, and she was unaware of what was being 
 done. On the eighth day the wound was dressed, and found healed, and it was 
 found that the senses of touch and pain over the aflPeeted area were good, except at 
 the tip of the little finger, where sensation was not distinct. On the twelfth day 
 the sensation was again tested, and it was found that all parts touched with the 
 point of a pin were correctly localised, except over the tip of the little finger. Though 
 felt, sensation was not so distinct as in the normal hand. She cried out when 
 pricked with a pin in any part of the affected area, except over the tip of the little 
 finger. The stitches were removed from the cutaneous wound, and on pressure over it 
 the abnormal sensation formerly felt had disappeared, and the flexor carpi ulnaris 
 was felt as a tense cord. The flexion of the hand had been by this time gradually 
 relaxed, and the arm was put on a splint, with the hand now extended. Electrical 
 treatment was commenced, and, while the faradic current gave no response, the 
 galvanic current gave contractions on closing, in the small muscles of the little 
 finger, but none could be detected in those of the palm. On the twenty-eighth day 
 the sensation was again compared in the two hands. The patient then stated that 
 she felt touch on the inside of the palm and back of the hand, and on the inside of 
 the ring finger, quite as well as in the corresponding parts of the left hand, but that 
 the sense of touch on the first and second internodes of the little finger, while 
 nearly as distinct, was not quite, while in the terminal phalanx of the little finger 
 gentle touches with the point of a pin were felt, but very indistinctly. When 
 pricked with a pin at any part other than the terminal phalanx of the little finger, 
 pain was the result, but in the latter the sensation was only that of touch. By the 
 beginning of the second month, the nutrition of the ulnar distribution of the hand 
 was showing signs of improvement, and sensation was improved in the terminal 
 phalanx of the little finger, pain being felt on pricking with a pin, as far as 4 millims. 
 
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DR. R. KENNEDY ON THE REGENERATION OF NERVES. 271 
 
 from the tip. The thermic sense was tested and found correct. By six weeks from 
 the date of operation, the last occasion upon which she was seen, the atrophy was less, 
 though still well marked, and, while the sensation remained almost perfect, there 
 was scarcely any improvement in motion. While she registered 22 kilos, on the 
 dynamometer with the left hand, she could only register 4 kilos, with the right. 
 
 III. — Deductions from the Results of Operation. 
 
 Cases of secondary suture are much more valuable for the study of certain questions 
 in the regeneration of nerves, than are cases of primary suture. In the former, if the 
 interval of time elapsed from the time of section till the operation undertaken for 
 repair, is suflBcient to allow a condition of stable equilibrium of the parts to be 
 attained, the deductions drawn from the results of operation are much less open to 
 dispute. I have shown in the first part of this paper, that theories have been put 
 forward to account for the early return of sensation after nerve suture, without 
 admitting the restoration of conductivity of the nerve, and the question to be decided 
 in the cases just described, is whether the return of function established, is due to a 
 true reunion of the nerve, or if it can be explained in any other way. 1 would refer 
 especially to the condition of sensation before and after operation. In the first three 
 cases, before operation, it was carefully determined that sensation was totally lost in 
 the regions of the skin supplied by the injured nerves, this loss including not only the 
 sense of pain, but also that of touch. In the fourth case it was also determined that 
 the sense of pain was absolutely lost in the region supplied by the ulnar nerve, but 
 that there was an obtuse sense of touch present on the little and inside of the ring 
 fingers, sufficient to enable the patient to know when her finger was touched. I 
 take this to be the mediate sensibility, described by LiTiEVANT (82), as sensation 
 produced by the impact against the anaesthetic region, being communicated to neigh- 
 bouring sound papillae, and thus conveyed along other nerves, without any direct 
 nerve communication existing between the part touched and the nerve conducting 
 the impulse. Thus the impulse produced by touch might in this case have been 
 conducted along the median or radial nerves, and learned from experience by the 
 patient to be, from its obscure character, referred to the anaesthetic area. The 
 absence of the sense of pain pointed to the conclusion, that the ulnar nerve was not 
 conducting, a conclusion which was justified at the operation, as the nerve was found 
 completely divided, and the ends lying apart. Leaving out of account the case in 
 which the nerves were compressed at the seat of fracture, these observations were 
 made at three, six-and-a-half, and eighteen months respectively, from the time of 
 injury, and after the operation the sense of pain made its appearance, in one at the 
 end of two days, in one at the end of three days, and in one at the end of five days. 
 I have already quoted some of the published cases with similar results, and shown 
 that none of the theories which have been advanced to account for early return of 
 
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272 DR. R. KENNEDY ON THE RBQENERATION OF NERVES. 
 
 sensation by channels other than that of the injured nerve, are applicable to such as 
 these. The finer anastomoses described by Arloing and Tripibr (70), or coarser 
 anastomoses, cannot have existed in these cases, as the sense of pain was totally lost ; 
 and the delay between the division of the nerve and the operation, without any return 
 of sensation, shows that no replacement, either by outgrowth from neighbouring 
 nerves as supported by Tjllmanns (123), or by development of fine collateral anasto- 
 moses as held by Remak (87), could have taken place. The speedy return of sensation 
 after the operation, therefore, leaves only the conclusion that the return was the 
 result of restoration of conductivity in the injured nerve. In making the tests for 
 returning sensation, the sense of pain was always taken by means of pricking the 
 skin with a pin, in order to avoid the possibility of mistaking mediate for immediate 
 sensibility ; for by mediate sensibility only touch is appreciated, and pricking the 
 skin with a pin, if felt, would only be as tactile sensation. 
 
 From the time of the first appearance of the sense of pain, sensation gradually 
 improved in the further course of the cases ; bat the cases showed differences in 
 progress. At first localisation of sensation was imperfect, but this very soon was 
 developed, and in about a month from the time of operation, in two of the cases, the 
 gentlest touches were distinctly felt and correctly localised. In one of the cases the 
 tip of the forefinger, and in another the tip of the little finger, were particularly long 
 in developing sensation. In the case in which the nerves were interrupted at the 
 seat of fracture, the return of sensation was less satisfactory, and it was not till the 
 eighth day that the sense of pain appeared in the palm, and not till six weeks that 
 it commenced to return in the fingers. This delay must be explained by the different 
 nature of the lesion in this case from that in the other cases. In the latter the injury 
 to the nerve was merely division, while in the former an indefinite length of nerve 
 was injured by the pressure of cicatricial tissue ; and although portions were removed 
 which seemed to be most involved, doubtless there were portions at a lower level 
 left, which were also much damaged by the pressure. The return of sensation in 
 the ulnar distribution in the first case is particularly remarkable ; for in that case 
 the divided ends of the ulnar nerve could not be brought together nearer than about 
 6 raillims. ; and yet in the little finger the sense of pain was developed in three days. 
 It must, therefore, be supposed either that the interval between the nerve ends was 
 bridged over in that time by a substance capable of conducting, or that by anastomotic 
 fibres the impulses were conducted along the median nerve in which the ends had 
 been brought into apposition ; but from the speed with w^hich sensation in the little 
 finger became perfected, it is more likely that the first view is correct. 
 
 In no case did improvement occur iu the muscles until a comparatively late period, 
 and as far as I was able to trace the cases, this function only approached a perfect 
 recovery in one case (Case II), and even in that case at the end of a year it was still 
 improving. This delay in the return of motion is an almost generally observed 
 occurrence, and some authors, explaining away the return of sensation, take only 
 
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DR. R. KENNEDY ON THE REGENERATION OF NERVES. 273 
 
 return of motion as a proof of the restoration of the conductivity of the nerve. But 
 the delay in the return of the motor function is easily intelligible when it is 
 remembered that for the recovery of motion, not only the nerve, but also the muscle 
 must undergo repair ; while for sensation, only the recovery of the nerve with its 
 end organs is necessary. The injury to the muscle is not only the result of its long 
 inactivity, but also of its long separation from its trophic centres. Thus it is that 
 in all the cases, even the third case, where the separation from the centres must have 
 been less than two months, the muscles tiffected showed great atrophy, and tested 
 electrically, gave the reaction of degeneration. Supposing, then, their nerve supply 
 to be restored at the time of the first appearance of sensation, the muscles only then 
 would begin to recover, and, in their weakened condition, their recovery must 
 necessarily be a very slow process ; and indeed, it is intelligible that in some cases 
 the muscles would be incapable of repair from their complete degeneration. The 
 gradual improvement in the first case was demonstrated by the return of faradic 
 irritability in the small muscles of the thumb, one and a half months after the 
 operation. The return of motion is also hindered by stiffness in the joints ; for, in 
 one of the cases, although at the end of a year all atrophy had disappeared, and 
 opposition of the thumb to the tip of the little finger, and abduction of the thumb 
 were easily performed, and although the strength of grip as tested by the hand 
 dynamometer, was almost as good as that of the sound hand, yet the stiffness of the 
 terminal joints of the index and middle fingers interfered with the strength of grip 
 for smaller objects, as it was impossible to bring the tips of these fingers into 
 the centre of the palm. (Plate 5, figs. 1 and 2.) 
 
 The operation in none of the cases gave rise to any untoward symptom. Tempera- 
 ture remained normal throughout, and the wounds healed by first intention. In the 
 second case, however, after the wound had apparently healed by first intention, a 
 small pustule formed, and pointed in the line of incision. On opening it, the sutures 
 which had been employed for the nerve came away, and the wouiid then speedily 
 healed. 
 
 The condition of the nerves found when exposed for suture was not the same in every 
 case. In every case the nerves appeared thickened as far up and down as they were 
 exposed, and this was not only exhibited in the central segment, but also in the 
 peripheral. The usual description of the peripheral segment which has been some 
 time separated from the central, is that it is found atrophied, but I did not find this 
 in any case. On the contrary, when the nerve had been sutured, it appeared as a 
 cord of uniform thickness above and below the seat of the suture. The divided ends 
 of the nerves were found in one of two conditions. In two of the nerves they were 
 united by a bulky cicatricial mass, while in two they were lying apart without any 
 apparent connexion one with the other. Where the nerve ends were united this 
 union was evidently not such as to enable function to be carried on. "Where the ends 
 were lying apart the central end in both cases presented a bulb of hard consistence, 
 
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 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 in one case ending in a tapering filament ; while the peripheral end presented in the 
 one case a small hard bulb, and in the other a conical ending. What may have had 
 something to do with the different character of the two peripheral ends, is the fact 
 that the end with the bulb was lying free in loose connective tissue, while the 
 end with the cone was lying firmly bound down to the underlying structures 
 by means of cicatricial bands. The prevailing opinion is that it is useless to^ do 
 more than raw the peripheral end before suturing, but I always cut off the terminal 
 portions, and the sections exposed always showed an appearance resembhng the 
 section of a nerve. 
 
 IV.— Microscopical Examination of the Portions removed previous 
 
 TO Suture. 
 
 1. Methods. 
 
 In every case the portions removed were immediately put into Muller's fluid, in 
 which they remained for several weeks, the fluid being changed at intervals. After 
 dehydration they were imbedded in paraffin, and both longitudinal and transverse 
 sections prepared with the Cambridge microtome, the sections being cut as thin as 
 possible. The sections were then fixed by the albumen method on slides in series, 
 and stained by various methods. The methods which I found to give the most 
 useful results were the first method of Weigert,* and the anilin-blue method of 
 Stroebe (158). I found it useful after staining by Weigert's method to stain the 
 preparation first with safranin and then with eosin, as by that addition the distribu- 
 tion of the nuclei and of the connective tissue was very clearly demonstrated, 
 
 2. Microscopical Appearances. 
 The following Table shows the portions examined. 
 
 Part examined. 
 
 Nerve. 
 
 Case. 
 
 Time between 
 
 injury and 
 
 excision. 
 
 Central balbons end 
 
 Peripheral bulbous end 
 
 Peripheral conical end 
 
 Cicatricial intercalary segment . . . 
 
 !. >> 11 ... 
 
 Portion compressed at seat of fracture 
 
 J) V J» >» 
 
 Ulnar 
 
 Median 
 
 )j 
 
 )) 
 
 Musculo-spiral with radial 
 
 and posterior interosseous 
 
 I. 
 IV. 
 
 I. 
 IV. 
 
 I. 
 II. 
 III. 
 III. 
 
 6^ months 
 
 18 months 
 
 6^ months 
 
 18 months 
 
 6| months 
 
 3 months 
 
 "1 Uncertain 
 
 >Not less than 
 
 J, four weeks 
 
 * Vide Lee, ' The Microtomist's Vade-mecum,' Lond., 1893, 3rd edition, p. 362, 
 
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DR. B. KENNEDY ON THE REGENERATION OP NERVES. 275 
 
 a. Central Ends. — The bulbs from the central segments were both very dense with 
 smooth surfaces. One lay surrounded by loose connective tissue, whUe the other was 
 adherent at its lower end to surrounding cicatricial tissue. The latter had a terminal 
 filament, but with that exception their appearance was similar. The following are 
 the microscopical characters of that from the ulnar of Case I. : — 
 
 Under a low power, a longitudinal section shows the nerve entering the bulb at 
 the side. The individual fasciculi bend round in entering the bulb, and when they 
 have entered, the fibres diverge, and spread in different directions throughout the 
 bulb, the fasciculi presenting thus at their entrance a fan shape. The bulb itself has 
 a clearly demarcated outline of connective tissue, but its interior presents a 
 heterogeneous aspect. In a common ground of connective tissue, there is every- 
 where thickly scattered small bundles of nerve elements. These bundles are cut in 
 all directions, some transversely, appearing as small round points, others longi- 
 tudinally, appearing as lines which frequently bifurcate, and others in all degrees of 
 obliquity. Here and there multitudes of transversely-cut bundles are grouped 
 together in islets, surrounded by longitudinally-cut bundles. 
 
 Under a high power (Plate 7, figs. I, 3, 5), the upper part of the entering fasciculi 
 shows chiefly normal nerve fibres, but the lower part, while showing occasionally a 
 normal nerve fibre, is made up of a mass of delicate bands. While the old fibres 
 measure in diameter about 9ju., the bands measure only about 3/i. in diameter. They 
 have attached to their sides numerous nuclei, the length of which is from five to 
 eight times their breadth, the more elongated measuring 13/a in length, and 1'6/a 
 in breadth. These bands have a granular appearance, and there is little doubt of 
 their being young nerve fibres, seeing that in the centre of many, a delicate thread, 
 the axis-cylinder, can be clearly distinguished. In many also Weigert's method 
 brings out a delicate myeline sheath, appearing as closely-set, bluish-black granules. 
 In the fasciculi which enter the bulb, these new-formed fibres lie in bundles, separated 
 by a few connective tissue fibres, running parallel with the nerve fibres. In the 
 region of transition between the old fibres and the new (Plate 7 , fig. 5), an actual 
 connexion between the axis-cylinders of the old and those of the new cannot be 
 traced. What, however, is clear, is that each bundle of new fibres corresponds to a 
 single old fibre, and in many cases the old fibre can be seen tapering off, its place 
 being taken by the new fibres, the number of new fibres becoming greater as the old 
 fibre diminishes, until finally only new fibres remain. In tracing further downwards 
 the groups of new fibres, the number contained in a single bundle increases, and, 
 while the bundle is thereby increased' in diameter, the fibres themselves retain a 
 fairly uniform breadth. 
 
 Passing into the bulb, there are here no old fibres to be found, but the whole 
 structure is made up of bundles of new fibres, cut in every direction, and surrounded 
 by a small amount of fibrous tissue. The bundles cut transversely are small in 
 diameter (Plate 7, figs, i and 3), yet the larger contain an enormous number of 
 
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276 DR. R. KENNEDY ON THE REaENERATION OF NERVES. 
 
 young nerve fibres. These fibres appear as clearly defined circles, containing each in 
 its centre a distinct axis-cylinder. The more prominent have a diameter of 3/*, but 
 there are some which have not more than half that diameter. Many have attached 
 to their sides a nucleus, which here has a circular outline, but which, when compared 
 with those in a longitudinally-cut bundle, is seen to be a section of a spindle-shaped 
 nucleus. The whole bundle is surrounded by a layer of connective tissue, but there 
 is no sheath proper. The fibres which show longitudinally, present the same 
 characters as the new fibres in the entering nerve already described. 
 
 Transverse sections of the upper part of the entering nerve in the central bulb of 
 Case IV., show that at this point the nerve has retained its normal arrangement of 
 fasciculi. While some of these fasciculi have retained at this level their normal 
 fibres, others have no old fibres, but instead, groups of young fibres (Plate 8, fig. 1). 
 These young fibres present characters identical with those of the fibres in the bulb 
 already described, but, as a rule, only from three or four up to a dozen are grouped 
 together in a single bundle. These bundles resemble very closely, both in number 
 and in disposition, the arrangement of the single old fibres in neighbouring fasciculi in 
 which the latter have been retained. Around these fasciculi the perineurium and 
 epineurium present normal characters, and the endoneurium appears also to be 
 normal. 
 
 The examination of the filament in which the bulb terminated, was made by serial 
 transverse sections. It is composed almost entirely of connective tissue, but at its 
 upper end there are about twenty or thirty small bundles of new nerve fibres. 
 Proportionately as the sections are taken from lower levels, the number of nerve 
 fibres diminishes, and the last section examined, still some distance from the termina- 
 tion of the filament, contains only three small bundles, each containing three or four 
 young nerve fibres. 
 
 b. Peripheral Ends.— The bulbous end, removed from the peripheral segment of 
 the ulnar in Case I., was about half the size of that removed from the central end, 
 and had also a firm consistence. 
 
 Under a low power, it presents a ground-work of connective tissue, in which lies 
 tissue stained bluish-black by Weigekt's method. This tissue runs in bundles, 
 longitudinally from the point at which the bulb was removed, towards the free end. 
 About the middle of the bulb, the more regular longitudinal course of these dark 
 stained bundles ceases, and the remainder of the section is occupied by the same 
 tissue, cut transversely and in various degrees of obliquity, showing thus many 
 circular bundles, isolated or in groups, with a' few bundles running longitudinally for 
 a short distance among them. 
 
 Examined with a high power, the sections show no old nerve fibres, but the tissue 
 stained by Weigert's method is identical in characters with the new nerve tissue 
 seen in the central bulb. In the distal half of the bulb, the fibres run chiefly 
 longitudinally, and are grouped into bundles, each of which contains many nerve 
 
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DR. R. KENNEDY ON THE BEaENERATJON OV NERVES. 277 
 
 fibres. These young fibres have the same characters as those in the central bulb. 
 Thus they have the same average diameter, have attached to their sides at very 
 short intervals, elongated nuclei, and have in many cases a delicate myeline sheath. 
 In many, a distinct axis-cylinder is visible, occupying the centre of the fibre. The 
 bundles are separated by fibrous tissue in greater or smaller amount, and in this 
 tissue are a number of round cells with granular contents. A few bundles appear 
 cut transversely, beside those cut longitudinally. In the proximal half of the bulb 
 it is rare to get the fibres running for any great distance in one plane. Thus the 
 majority appear cut transversely or obliquely. The connective tissue here is in 
 larger quantity than at the attached end of the bulb. The bundles of nerve fibres 
 cut transversely are of different size, but, irrespectively of that difference, the 
 contents are identical. They contain (Plate 7, figs. 2 and 4) from a few up to twenty 
 or thirty closely aggregated young nerve fibres. The larger of these measure in 
 diameter 3yx, have a well-defined circular outline, and contain each in its centre a 
 distinct point, the axis-cylinder. There are also many much smaller fibres with 
 similar characters. The bundles also contain the sections of nuclei, the larger of 
 which are about one half the diameter of the larger fibres. Around the bundles, one 
 or two layers of connective tissue are arranged concentrically, but there is no definite 
 sheath. 
 
 The conical portion removed from the peripheral segment in Case IV., also contains 
 no old nerve fibres. It has a very dense structure, the nerve elements and connective 
 tissue being very closely aggregated together. A few transverse sections removed 
 from the base of the cone, show the majority of the new fibres in bundles cut trans- 
 versely (Plate 8, fig. 2), but even at that level a few are cut longitudinally and 
 obliquely. Similarly, in longitudinal sections of the cone, there is no part in which 
 the bundles run exclusively in one direction. Towards the apex of the cone the 
 number of fibres diminishes, and the section appears entirely composed, ultimately, 
 of connective tissue. The characters of the fibres here are identical with those of 
 the fibres already described, but a few show the formation of the myeline sheath 
 more distinctly than those either in the peripheral or central bulbs of Case I. In 
 some of the fibres, it has taken on the stain so deeply that the contents of the fibre 
 are quite hidden, and it appears as a uniform granular coat. 
 
 The cone terminated in a filament about 12 millims. in length, and this was 
 examined for nerve fibres by serial transverse sections, but none were found. The 
 core of the filament is occupied by a blood vessel, and the remainder is simply 
 connective tissue. 
 
 c. Intercalary Cicatricial Segments. — The cicatricial mass which united the two 
 ends of the median in Case I., measured 1-5 centim. in length and 1 centim. in 
 breadth. It had a rough and somewhat irregular surface and firm consistence. It 
 was thicker in the middle, and narrowed to the thickness of the nerve at either end. 
 
 Transverse sections from its proximal end (Plate 8, fig. 3) show a network of 
 
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278 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 dense fibrous tissue, containing in its meshes bundles of nerve elements. In some 
 parts the connective tissue fibres run longitudinally, appearing as points in section, 
 but in others tliey run transversely, being there displayed, in a large part of their 
 course in the section. The bundles of nerve elements are uniformly distributed 
 throughout the section, but they are small, the larger measuring only 30/a in 
 diameter, and are isolated from each other by a considerable breadth of dense fibrous 
 tissue. Some are very small, containing only two or three fibres, while the larger 
 contain as many as twenty. All the fibres exposed are small new fibres, no old 
 fibres being present. These fibres agree in characters with those already described. 
 They have a very sharply defined outhne, the axis-cylinder is very distinct, and 
 there are many nuclei lying between them and attached to their sides. Many of 
 these fibres are larger than any met with in the other cases, some measuring 4/* in 
 diameter. 
 
 The distal end of the mass presents a less regular aspect. In some parts (Plate 8, 
 fig. 4) there are dense masses of fibrous tissue, and only isolated bundles of nerve 
 elements, grouped together, while in other parts (Plate 9, fig. 1), the distribution of 
 the nerve elements is very uniform. These uniformly distributed bundles are still 
 smaller than the bundles in the proximal end, the largest measuring 17ju, in diameter, 
 but the majority much smaller. The larger contain eight or ten young fibres, and 
 the smaller from two to three or four. In addition to these, there are many isolated 
 fibres. The young fibres are the same in structure as those in the opposite end of 
 the mass. The bundles do not all appear in transverse section, but a few appear 
 running longitudinally in the section, and, therefore, transversely in the mass, and a 
 few obliquely cut. In these the spindle-shaped nuclei attached to the sides of the 
 fibres are displayed. Also in many such fibres the axis-cylinders are shown as 
 delicate threads (Plate 8, fig. 4). 
 
 The characters of this mass, which have been described from transverse sections 
 from its two opposite ends, are shown by longitudinal sections to be maintained 
 thi'oughout the whole mass. The arrangement of the bundles is very irregular. In 
 the same longitudinal section are to be seen islets of transversely-cut bundles 
 (Plate 8, fig. 5), and coursing around them, bundles cut longitudinally and obliquely. 
 Some of the longitudinally-cut bundles contain fibres which show very well the 
 developing myeline sheath, not, however, sufficiently dense to hide the delicate axis- 
 cylinder (Plate 8, fig. 6). 
 
 The intercalary mass fi-om the median of Case III. agrees in characters with that 
 just described so closely that a separate description is unnecessary. 
 
 d. Portions Compressed at Seat of Fracture.— The portion excised from the 
 median, and that from the musculo-spiral with its two branches, are examples of 
 nerves which have been under compression for several weeks. 
 
 The portion excised from the median measured in length only about 12 millims. 
 yet transverse sections from the proximal and distal ends show very different 
 
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DR. R. KENNEDY ON THE REGENERATION OP NERVES. 279 
 
 structures. The transverse section of the proximal end (Plate 9, fig, 2) is practically 
 that of a normal nerve, sliowing throughout a normal subdivision into fasciculi, 
 surrounded each by a normal perineurium, and each containing normal myeline fibres, 
 the majority of which measure about 8fi in diameter. The section agrees in every 
 particular with transverse sections of normal human nerves, which were treated by 
 the same methods for comparison. The transverse section of the distal end shows a 
 normal subdivision into fasciculi, and, under a very low power, looks like the section 
 of a normal nerve, with the exception that, treated by Weigert's method, the 
 fasciculi are not stained so deeply. With a high power, however (Plate 9, fig. 3), 
 the difference from the normal nerve is very decided, for the fasciculi contain no old 
 myeline fibres, but in their place groups of young fibres. Tlie perineurium surround- 
 ing each of the fasciculi has a normal appearance, but the endoneurial tissue has, if 
 anything, a stronger development than normally. The groups of young fibres are 
 small, the majority measuring about 8)u, in diameter, with here and there a few 
 larger examples. As a rule, they contain only three or four young nerve fibres, each 
 presenting a sharp circular outline, and containing an axis-cylinder in its centre, 
 together with one or two nuclei, either lying between the young fibres or at the 
 circumference of the small bundle. Most of the bundles are surrounded by a delicate 
 membrane. All the bundles shown in the section are transversely cut. The 
 epineurium is normal, and no young fibres are found between the layers of the 
 perineurium. 
 
 The portion removed from the musculo-spiral nerve and its two branches included 
 the terminal 12 millims. of the former, with 6 millims. of the radial, and 3 milliras. of 
 the posterior interosseous. The transverse section of the proximal end of the 
 musculo-spiral is normal, while those of the distal ends of the radial and posterior- 
 interosseous present no old nerve fibres, but instead, groups of young fibres arranged 
 as in the distal end of the portion of the median just described. In the transverse 
 sections which have passed through the region of transition from the old fibres to the 
 new, some of the fasciculi show an arrangement of old myeline fibres which is that of 
 a normal nerve, but many of the myeline fibres have an abnormal character. In the 
 simplest of these, the axis-cylinder is greatly hypertrophied, and the whole fibre is 
 enlarged (Plate 9, fig. 5). In others, between the sheath of Schwann and the 
 myeline sheath is a large nucleus, presenting a circular outline. In another, in 
 addition to the large nucleus, and lying alongside of it, are one or two very distinct 
 young nerve fibres with clearly-defined circular outlines, and delicate axis- cylinders, 
 while the myeline sheath of the old fibre is indented by the new-formed structures, 
 and the old sheath of Schwann is slightly distended (Plate 9, fig. 5). The old fibre, 
 however, has still its characters preserved. The majority of such old fibres measure 
 about 12/A in diameter, while the new fibres intercalated between the sheath of 
 Schwann and the myeline sheath measure 3fi in diameter, and the nucleus has a 
 diameter approximately the same. Other old fibres in the same section present 
 
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280 DR. R. KENNEDY ON THE REG-ENBBATION OE NERVES. 
 
 three, four, and up to a dozen newly-formed fibres lying in the same position, and 
 the number of nuclei present is proportionately increased to two, three, or more. 
 Just as the old fibres present a greater number of young fibres, so the old myeline 
 sheath and axis-cylinder appear crushed to the one side and diminished (Plate 9, 
 figs. 6 and 7). In some, in which the old sheaths of Schwann contain about a dozen 
 new fibres, traces of the old axis-cylinder and myeline sheath can still be seen at one 
 side of the group, while, in other cases, no trace of the old myeline sheath and axis- 
 cylinder can be found, and there is merely a group of young fibres with nuclei, 
 surrounded by the old sheath of Schwann. Those old fibres, which still contain the 
 myeline sheath and axis-cylinder, and yet have young fibres between the myeline 
 sheath and sheath of Schwann, show the latter sheath distended in proportion to 
 the number of young fibres present. Also, where the myeline sheath and axis- 
 cylinder of the old fibres have disappeared, many show the old sheath of Schwann 
 surrounding the group of young fibres, but, in some, where the number of young 
 fibres in a bundle is great, the old sheath of Schwann is very difficult to trace. 
 
 A longitudinal section made through the same region shows the old myeline fibres 
 terminating and giving place to the young fibres (Plate 9, fig. 4) ; and the sheath, 
 enclosing the bundle of young fibres, can often be traced into continuity with the old 
 sheath of Schwann. The more common condition traced from the old fibre above 
 down into the bundle of young fibres is as follows : — The old fibre gradually increases 
 in diameter, and presents finally what approaches a bulbous condition. In its interior 
 the axis-cylinder is swollen and presents in many cases a bulb. Beyond this the old 
 myeline sheath and axis-cylinder contract greatly and terminate almost immediately. 
 The sheath of Schwann is continued beyond the bulbous myeline fibre as the sheath 
 surrounding the bundle of young fibres. Often, before the termination of the old 
 fibre is reached, isolated young fibres can be seen, running between the sheath of 
 Schwann and the myeline sheath. These pass downwards, until they are lost in the 
 bundle of young fibres beyond the old. The nuclei seen in transverse sections as 
 circular are here shown to be spindle-shaped. 
 
 Y. — Deductions from the Microscopical Appearances. 
 
 1. Degeneration. 
 
 The length of time which has elapsed from the time of injury till the examination 
 of the nerve in these cases, precludes the study of the earlier stages of degeneration 
 but allows certain deductions concerning the later stages and final result of the 
 process. 
 
 The sheath of Schwann, notwithstanding the lapse of several weeks from the 
 commencement of compression, still remains in the portions of nerve from Case III. 
 (Plate 9, fig. 3). It can be traced downwards from the old fibre into the region of 
 
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DR. R. KENNEDY ON THE REGENERATION OF NERVES. 281 
 
 the new fibres, where, for a time, it is retained (Plate 9, fig. 4). But as the new 
 fibres increase in numbers, the old sheath is gradually distended, and ultimately 
 becomes unrecognisable, probably becoming part of the endoneurial connective tissue. 
 This, then, accords with the view expressed in the recent papers by Bungnbr (150), 
 Howell and Hueer (156), Stboebe (158), and Notthafft (159), that the sheath of 
 Schwann is retained for a time after degeneration of the other parts of the fibre, but 
 that it is destroyed during the regenerative process. 
 
 Where the old sheath of Schwann is still retained, it contains nothing which could 
 be taken for the old axis-cylinder. The latter, traced into the region of compression, 
 is seen terminating, often in bulbous ends, and below that, the contents of the old 
 sheath are only new-formed elements (Plate 7, fig. 5 ; Plate 9, fig. 4). In other cases, 
 the gradual disappearance of the old axis-cylinder can be seen in transverse sections 
 through the point of transition from old to new fibres (Plate 9, figs. 5, 6, and 7). In 
 the portions of nerve removed from peripheral segments there are no old fibres to be 
 seen, and no structures which could be taken for old axis-cylinders. My results are, 
 therefore, not in accord with the view taken by Schiff (31), Philipeaux and 
 VuLPiAN (39), WoLBERG (127), and others, that both the old sheath of Schwann 
 and the old axis-cylinder are retained in the whole peripheral segment. Ranvier 
 (102), also, while he finds that the axis-cylinder is destroyed in the peripheral 
 segment, holds that it is retained in the central, unless exceptionally, and that the 
 degenerative process affects only the extremely small portion of the central segment 
 measured by one or two of the nodes now called by his name. But in the central 
 bulbs examined there are portions of the old nerve, about 6 millims, in length, 
 attached to the side of the bulb, and it is only at the extreme upper part of this 
 that old fibres are present, while the remainder is entirely occupied by new fibres, 
 among which no trace of the old axis-cylinders is visible. 
 
 The view taken by Kraitse (136) that the sensory fibres from the touch corpuscles 
 of Wagner and Meissner, having their nutritive centres there, undergo degenera- 
 tion in the central segment, while they remain sound in the peripheral segment, has 
 been taken as an explanation of the conflicting results of other authors. Krause 
 found that transverse sections of the central segment showed about one-half of the 
 fibres degenerated, while he merely assumed that in the peripheral segment there 
 were a corresponding proportion of the fibres which remained sound, his assumption 
 being based on analogy with the condition found in rabbits. But in the transverse 
 sections made from the proximal ends of the portions from the median and musculo- 
 spiral nerves of Case III., the appearances presented are those of a normal nerve (Plate 9, 
 fig. 2) ; in none of the fasciculi are any new fibres found, and there has therefore been 
 no degeneration. Also, in portions removed from peripheral segments, no old fibres 
 are present. I cannot, therefore, agree with Kraitse that there is an immediate 
 ascending degeneration in the central segment, for the proportion of fibres indicated 
 by him as becoming degenerated in the central segment is so great that there would 
 
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282 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 be no difficulty in seeing them if present, or the resulting regeneration in any case. 
 This is also the opinion expressed by Gottsaoker (145) from examination of stump 
 neuromata. From the account given by S, Meyer (100, 108, 125), Hammer (161), 
 and Teuscher (149), it would appear that in any nerve there are always to be found 
 degenerated fibres ; but that these are present only very sparingly, and are due to 
 a normal process of degeneration. Krause's results were obtained from the exami- 
 nation of nerves in limbs amputated for gangrene. Several of these were senile or 
 diabetic gangrene, and it is, therefore, possible that in his cases the degenei"ation of 
 the nerve was primary to the gangi'ene. This is more likely, if we are to regard, with 
 S. Meyer, the nerve fibres, not as perennial structures, but as undergoing a normal 
 process of degeneration and regeneration ; and this view is supported by the work of 
 Korybutt-Daszkiewicz (105), who found an active formation of nerve-fibres in the 
 nerves of the frog, on placing the frogs in favourable surroundings, after a period of 
 starvation. In any case, if an immediate ascending degeneration were caused by 
 interruption of the course of a nerve, there would have been some evidence of that in 
 the transverse sections of the proximal ends of the median and musculo-spiral portions 
 from Case III. 
 
 2. Regeneration of nerve fibres in the peripheral segment, while still separated from 
 
 the central segment. 
 
 The portions of nerves examined show very clearly, not only that in regeneration 
 the young fibres are produced both in the central and in the peripheral segment, but 
 also that reunion of the ends is not an essential to the production of young fibres in 
 the peripheral segment (Plate 7, figs. 2 and 4 ; Plate 8, fig. 2). This independent 
 origin of new fibres in the peripheral segment, without previous reunion with the 
 central end, first observed and described by Philipeaux and Vulpian (38, 39), has 
 been opposed by almost all who have since made a study of regeneration of nerves ; 
 and their opinion was also greatly weakened by the fact that Vulpian (77, 86) him- 
 self withdrew from his former position. Mitchell (80), and recently Bowlby (146) 
 have found in the examination of portions removed from the peripheral segments of 
 un- united divided nerves, that many newly formed nerve fibres are there present. 
 The opponents of this view give various explanations of the results of these observers. 
 Some hold that Philipeaux and Vulpiatst mistook products of degeneration for young 
 fibres ; Schiff (41), and Ambrosoli (43) that their results were only to be got in 
 very young animals; while Ranvier (102), again, thinks that they did observe the 
 periphei'al segment regenerated, but that they had failed to observe certain strands 
 of tissue between the central and peripheral ends, through which the peripheral 
 segment had been regenerated. He supports this allegation by an observation of his 
 own, -where a central segment lying separate from its peripheral, was connected to it 
 by a membrane having the appearance of connective tissue, but which contained 
 nerve fibres, as shown by the tint which it took on being subjected to the action of 
 
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DR. R. KENNEDY ON THE REGENERATION OF NERVES. 283 
 
 osmic acid. Howell and Huber (150) iu opposing tiie results of Bowlby, hold that 
 the young fibres which he observed, were simply sections of nuclei, and that the point 
 in their interior, taken for the axis-cylinder, was nothing more than the nucleolus, 
 and state that this explanation is more likely, since Bowlby figures no nuclei among 
 the bundles of fibres, It is ti"ue that in Bowlbv's figures there are no nuclei shown 
 among the young fibres, and he believes that the axis-cylinders are formed by the 
 nuclei. But in my prepai'ations thei-e can be no doubt of the structures in question 
 being young nerve fibres ; for the axis-cylinder shown in transverse section as a point, 
 is clearly visible in many fibres seen longitudinally, as a delicate thread. Also in the 
 bundles which are cut transversely, nuclei are always present (Plate 7, fig. 4), lying 
 between the fibres, and in many cases distinctly attached to the fibres ; and in fibres 
 seen longitudinally these nuclei are spindle-shaped, and distinctly attached to the 
 sides of the fibres. The difference between the axis-cylinders and the nuclei of a 
 bundle is well shown in some of the preparations, which were stained by the method 
 recommended by Stroebe ; for the former have taken on the aniline blue, while the 
 latter have taken the red colour of the safranin. But that they are really nerve fibres, 
 does not rest alone on the axis-cylinder being demonsti'ated, for they also in many 
 cases show a commencing myeline sheath. In order to find if they could possibly have 
 been communicated to the peripheral segment from the central end of the nerve 
 through fine bands of tissue connecting the ends as suggested by Banvier, I made a 
 careful search for such. In one of the cases such were present, in the form of 
 fine filaments, one attached to the central end, and one to the peripheral, but without 
 any connexion one with the other. In tha,t attached to the peripheral, there were 
 no nerve elements present, while in that taken from the central end, the upper 
 portion contained only a few isolated bundles of young nerve fibres, which gradually 
 diminished in numbers, as the sections were taken further away from the bulb, until in 
 the last section taken, still some distance from the termination of the filament, only 
 three small bundles remained. I found, therefore, no means of communication between 
 the ends, and must conclude that the young fibres observed in the peripheral segment 
 have an independent origin there. 
 
 Vanlair (122) found in the sciatic nerve of a dog, that four months after resection 
 of a portion there was reunion of the ends by a cicatricial segment, but no functional 
 return. The cicatricial segment, he found regenerated, but the peripheral segment 
 contained only fibres which he regarded as end products of degeneration, and called 
 " atrophic degeneration." His description of these fibres agrees with the appearance 
 presented by newly- formed fibres, and I think it probable that they were such, and 
 not the products of degeneration. 
 
 3. The Origin of the Young Fibres. 
 
 The arrangement, wherever they are found, of the new fibres in bundles suggests 
 that the fibres composing each bundle have had a common origin. As a rule, the 
 
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284 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 number contained in a single bundle is great. The part of the nerve in which they 
 originate can be seen, when sections from the central segment close to the termination 
 of the old fibres are examined ; for, while the young fibres are there seen Still in 
 bundles, these bundles are small, and contain few young fibres. The diameter of 
 these small groups of fibres is approximately the same as that of a single old fibre, 
 and the sheath of Schwann can be traced down in longitudinal sections, from the 
 old fibre into the region of the new, where it is seen surrounding the small bundle 
 of new fibres {Plate 9, figs. 3 and 4). It is clear from this that these young 
 fibres originate within the sheath of Schwann, On tracing them downwards m 
 longitudinal sections, they are found to increase in numbers and distend the sheath 
 of Schwann, which ultimately becomes unrecognisable. It is thus probable that the 
 young fibres of each of the bundles which appear in the central bulb and in the end 
 of the peripheral segment, represent in most cases fibres which have had a common 
 origin from within one old sheath- of Schwann. 
 
 The epineurium and perineurium appear normal in the portion of nerve immediately 
 proximal to the central bulb, and in the portions removed from the seat of com- 
 pression (Plate 8, fig. 1 ; Plate 9, fig. 3). There is, therefore, nothing to 
 indicate an origin of nerve fibres from the cells of the perineurium as described by 
 H,TELT (44), WoLBERG (127), and Hanken (143). Also the vieW of Vanlair (122) 
 that the new fibres proceed into the perineurium, and out into the epineurium, 
 forming a zone round the fasciculus, has nothing to support it in my preparations. 
 
 If, then, the new fibres originate within the old sheath of Schwann, they must be 
 formed either by growth from the old fibre above, as described by Eanvier 
 (8L, 102) and others ; or from the remains of the old fibre, as held by many; or 
 from the protoplasm and nuclei of the sheath of Schwann, as held by Bungnek 
 (150) and others. The manner in which the old fibre ceases abruptly, and gives place 
 to many young fibres which occupy the continuation of its sheath of Schwann, may 
 suggest an origin such as described by Ranvier aiid others; but the presence of 
 undoubted young nerve fibres in the peripheral segment, while it has no connexion 
 with the central segment, is incompatible with this view. The young fibres also 
 cannot originate from the remains of the old, as in the region of transition from the 
 old to the new, both old fibres and young are seen enclosed within a common sheath 
 of Schwann (Plate 9, figs. 5, 6 and 7). Thus the only source left from which 
 to derive the young fibres within the old sheath of Schwann, is the nucleus and 
 protoplasm of the intezannular segment. This conclusion is strengthened by the 
 examination of transverse sections, passing through the point of transition from the 
 old fibres to the new ; for there, the old fibre can be seen with one or more young 
 fibres lying beside the nucleus, and between the sheath of Schwann and the myeline 
 sheath (Plate 9, figs. 5 to 7). The enormous number of spindle-shaped nuclei 
 among the nerve fibres, indicates that these structures have Originated by prolifera- 
 tion from the nuclei of the sheath of Schwann, but in my preparations the 
 
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DR. R. KENNEDY ON THE REGLINERATiON OF NERVKS. 285 
 
 proliferative stage had evidently come to a conclusion, as no indications of 
 karyomitosis were present. 
 
 My results are, therefore, in accord with the opinion expressed in Bungner's 
 recent paper, that the nuclei and protoplasm of the interannular segments must be 
 viewed as neuroblasts, their function being to produce nev/ nerve fibres. And, 
 taking into account the observations of S. Meyer (100, 108, 125), it would appear 
 that the exercise of their function is not reserved for accidents such as nerve section, 
 but occurs normally, the fibres undergoing a normal degeneration and regeneration. 
 The bundles of young fibres were seen by Howell and Huber (156) in the 
 peripheral end of nerves which had not united, but having failed to stain the axis- 
 cylinder they call them " embryonic fibres," and find that they receive axis-cylinders 
 only by growth of the latter from those of the old fibres in the central end. That 
 these fibres observed by Howell and Huber were really nerve fibres, is shown by 
 the fact that when the peripheral segment, containing only such, was mechanically 
 irritated, a low degree of irritability and conductivity was found. 
 
 4. Characters of the Young Fibres. 
 
 The young fibres appear with a central axis-cylinder, with a protoplasmic surround- 
 ing zone, having a well-defined outline, and with spindle-shaped nuclei attached at 
 short intervals to their sides. It is evident, therefore, that the nuclei do not form 
 the axis-cylinder as described by Bowlby (146), but that in the formation of the 
 fibre only the central portion of the primitive protoplasmic thread becomes developed 
 into the axis-cylinder. In many fibres, both in the central and peripheral ends, the 
 protoplasmic zone contains a granular deposit which takes on the characteristic tint 
 of myeline by treatment with Weigert's method (Plate 8, fig. 6). It is, therefore, 
 clear that the myeline sheath is deposited in the protoplasm gradually and uniformly. 
 In transverse section the young fibres correspond in appearance and in diameter (3/u,) 
 with the "fibres h, gaine vitreuse" of Vanlair (122), and according to him the 
 " gaine vitreuse " is a provisional covering of the axis-cylinder, derived from the 
 connective tissue around, which becomes thinner as the normal sheaths of the axis- 
 cylinder develop, and finally becomes the fibrillar sheath. I think it more probable 
 that the zone surrounding the axis-cylinder is the protoplasmic residue not used 
 up in the formation of that structure, and that after the myeline sheath becomes 
 deposited within it, it remains with the nucleus as the protoplasm of the inter- 
 annular segment. 
 
 Independently of the time which has elapsed from the injury till the excision of 
 the portions of nerve examined, the stage of development of the young fibres is the 
 same, with the exception that some show more distinctly than others the commencing 
 myeline sheath ; and this similarity occurs both in the central and peripheral ends. 
 As this time varied from a few weeks to eighteen months, the development presented 
 
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286 DR. E. KENNED? ON THE REGENERATION OF NERVES. 
 
 by the fibres must be regarded as a resting stage. It is probable that the further 
 steps in development to the adult fibre depend on a restoration of continuity of the 
 nerve, and that such as Avould allow the transmission of impulses through the young 
 fibres. Also the observation of Philipeaux and Vulpian (39) that regeneration is 
 more rapid when union is effected, may be exjolained on the view that reunion is 
 necessary to the further development of the fibres. That these young fibres are 
 capable of transmitting impulses, I take the observations of Howell and Huber as 
 proving ; and this explains also why, after the operation of suture, so rapid a return 
 of sensation in the parts previously anaesthetic occurs. 
 
 With regard to the formation of the new sheath of Schwann, it might be viewed 
 as a metamorphosed outer layer of the yoimg fibre, but this is unlikely from the 
 behaviour of the old sheath. For, since that structure does not degenerate along 
 with the rest of the fibre, and is only finally destroyed or displaced by the 
 mechanical condition that it is no longer able to contain the developing fibres, it 
 does not act as part of the fibre. It is more probable that it is an addition to the 
 fibre from the surrounding connective tissue. 
 
 On comparing the transverse section of a nerve made through a part which 
 contains the old fibres, with one made further down in the region containing new 
 fibres, the increase in numbers of the new fibres as compared with the old is very 
 striking. It is seen that the number of groups of the new fibres is approximately 
 equal to the number of old fibres, and as each group contains at a high level three 
 or four, and at a Jower many more, the numerical increase may be roughly estimated 
 (Plate 9, figs. 2 and y). It is hardly likely that all such fibres are developed to the 
 stage of maturity. It may be that when reunion is established, only the normal 
 number of fibres develop further, while the others perish or remain undeveloped ; but 
 this is a subject upon which there is as yet no evidence. 
 
 5. Cicatricial Intercalary Segments. 
 
 The nature of the cicatricial mass, uniting two ends of a nerve by a bond which 
 does not allow re-establishment of function, is illustrated by two of the cases. In 
 these, although the mass has the appearance of cicatricial connective tissue, yet the 
 microscopical examination shows that from end to end the mass contains a rich 
 supply of young nerve fibres. But at the same time, these young fibres are 
 separated by much dense connective tissue, which in some places is massed together 
 to the exclusion of young nerve fibres (Plate 5, figs. 3 to 6 ; Plate 6, fig. 1). This 
 mass has evidently been supplied with nerve fibres by immigration into it of 
 neiiroblasts, either from the central end or from both. I think from both ends, from 
 the fact that both central and peripheral ends of nerves, remaining entirely 
 separated, show at their ends a mass of connective tissue containing nerve fibres. 
 The latter do not run in parallel lines, as they do when met in a piece of old nerve, 
 
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DR. R. KENNEDY ON THE REGENRRATTON OF NERVES. 287 
 
 but are convoluted, shoAving that they have been developed in the irregular spaces 
 of the connective tissue. But if a cicatricial mass connecting the two ends of a 
 (Hvided nerve is thus supplied with nerve fibres from the central and peripheral ends, 
 there must be some cause preventing the transmission of impulses. The explanation 
 which seems to me most probable, is that if there has been much inflammation in the 
 parts, the amount of cicatricial tissue in the mass is so great, that by the time the 
 mass is bridged over by nerve fibres, the contraction of the cicatricial tissue has 
 become so great, that the nerve fibres are prevented from transmitting impulses or 
 developing further, in a way exactly analogous to that which occurs when a nerve is 
 involved in the callus of a fracture. 
 
 VI. — General Conclusions. 
 
 1st. Un-united divided nerves, sutured long after division, can re-unite and 
 transmit impulses in a few^ days. 
 
 2nd. After division or interruption of a nerve, there is no ascending degeneration 
 of the kind described by Krause. 
 
 3rd. The old axis-cylinder is destroyed in the peripheral segment, and in the 
 ultimate portion of the central segment. 
 
 4th. New fibres originate in the peripheral segment as well as in the central end. 
 
 5th. The formation of new fibres in the peripheral segment occurs, although there 
 is no connection with the central end, but maturation of the fibre is not completed 
 while separation of the ends lasts. 
 
 6th. The new fibres originate from cells within the sheath of Schwann. 
 
 7th. In the development of the young fibres, the central portion of the primitive 
 protoplasmic thread forms an axis-cylinder, and the myeline sheath is deposited in the 
 surrounding protoplasmic zone, which latter remains along with the nucleus as the 
 neux'oblastic element of the interannular segment. 
 
 8th. The cicatricial mass uniting the ends of a divided nerve may be permeated 
 by young nerve fibres from end to end without functional union being effected, if the 
 amount of cicatricial connective tissue present in the mass is suflicient by its pressure 
 to prevent the passage of impulses. 
 
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 Mikros. Anat., vol. 29, 1887, p. 464. 
 
 141. Jacobi, RuD. Ein merkwtirdiges Sensibilitatsphanomen. Berl. Kl. Wochenschr., 
 
 Juni, 1887, pp. 412, 452. 
 
 142. Hochwart. Ueber De- und Regeneration von Nervenfasern. [Wien. Med. 
 
 Jahvbb. N. F., IL, 1, p. 1, 1887.] Schmidt's Jahrbiicher, 1887, vol. 215, 
 p. 17; vol. 216, p. 130. 
 
 143. Hanken. Ueber die Folgen von Quetschung pevipherischer Nerven. [Internat. 
 
 Mon. Schr. f. Anat. u. Histol., III., 8, p. 265. J Schmidt's Jahrbiicher, 
 vol. 216, p. 129. 
 
 144. Hrs. Die Entwickelung der ersten Nervenbahnen beim menschlichen Embryo. 
 
 Uebersichtliche Darstellung. Archiv f. Anat. u. Physiol. (Anat. Abth.), 
 1887, p. 368. 
 
 145. Gottsacker, Anton. Ueber Stumpfneurome. Inaug. Dissert., Bonn, 1889. 
 
 146. BowLBY, Anthony. Injuries and Diseases of Nerves and their Surgical Treat- 
 
 ment. Loudon, 1889. 
 
 147. His. Die Nearoblasten und deren Entstehung im embryonalen Mark. Archiv 
 
 f. Anat. u. Physiol. (Anat. Abth.), 1889, p. 249. 
 
 148. Rose, Edmund. Eine Knochelamputation mit spontauer Nervenregeneration. 
 
 Aus der freien Vereinigung der Chirurgen Berlins, 1890. Beitrage zur 
 Conservativen Chirurgie, p. 461. 
 
 149. Teuscher. Ueber Degeneration am normalen peripheren Nerven. Archiv f. 
 
 Mikr. Anat., 1890, vol. 36, p. 579. 
 
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296 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 150. V. BuNGNER, Otto. Ueber die Degenerations- und Eegenerationsvorgange am 
 
 Nerven nach Verletzungen. Ziegt.^r's Beitrage zur Pathol og. Anat., 
 vol. 10, 1891, p. 321. 
 
 151. MiTROPHANOW. Sur la formation du systeme nerveux pdriph^rique des Yer- 
 
 tdbres. Compt. Eend. de I'Aead., vol. 113, 1891, p. 659. 
 
 152. Harrisson. Nerve Grafting. Lancet, 1892, vol. 1, p. 691. 
 
 153. Vanlair, C. Des alterations nerveuses centripetes consdcutives h. la section 
 
 des nerfs et aux amputations des membres. [Bruxelles, Acad. Royale de 
 Med. de Belgique.] Virchow-Hirsch, Jahresber., 1892, II., p. 282. 
 
 154. HuBER, G. Carl. Ueber das Verhalten der Kerne der Schwann'schen Scheide 
 
 bei Nervendegeneration. Archiv f. Mikros. Anat., vol. 40, 1892, p. 409. 
 
 155. V. BuNGNER. Bemerkung zu der Arbeit von Professor G. C. Huber. Archiv f. 
 
 Mikros. Anat., vol. 41, 1893, p. 146. 
 
 156. Howell and Huber. A Physiological, Histological, and Clinical Study of the 
 
 Degeneration and Begeneration in Peripheral Nerve Fibres after Sever- 
 ance of their Connections with the Nerve Centres. Journ. of Physiol., 
 vol. 13, 1892, p. 335 ; vol. 14, 1893, p. 1. 
 
 157. Vanlair, C. Survie apr^s la section des deux nerfs vagues. Compt. Eend. de 
 
 lAcad., vol. 116, 1893, p. 330. 
 
 158. Stroebe. Experimentelle Untersuchungen libei' Degeneration und Eegenei'a- 
 
 tion peripherer Nerven nach Verletzungen. Ziegler's Beitrage, 1893, 
 vol 13, p. 160. 
 
 159. V. NoTTHAEET. Neue Untersuchungen liber den Verlauf der Degenerations - 
 
 und Eegenerationsprocesse am verletzten peripheren Nerven, Zeitschr. 
 f. Wissensch. ZooL, vol 55, 1893, p. 134. 
 
 160. Vanlair, C. Eecherches chronometriques sur la regeneration des nerfs. 
 
 Archives de Physiol, norm, et patholog., 5th Series, vol. 6, 1894, p. 217. 
 
 161. Hammer. Ueber Degeneration im normalen peripheren Nerven. Archiv f. 
 
 Mikros. Anat., vol. 45, 1895, p. 145. 
 
 162. Huber, G. Carl. A Study of the Operative Treatment for Loss of Nerve 
 
 Substance in Peripheral Nerves. Journ. of Morphol., vol. 1 1, 1895, p. 629. 
 
 163. Bergman, E. Ueber die aufsteigende Degeneration der sensiblen und moto- 
 
 rischen Gehirnnerven. [Pamietnick Towarzystwa Lekarskiego Warszaws- 
 kiego, 1895, vol. 91, p. 25. J Virchow's Jahresber., 1895, vol 1, p. 221. 
 
 164. Fleming, Egbert A. Some Notes on Ascending Degeneration (so-called), and 
 
 on the Changes in Nerve Cells consequent thereon. Brit. Med. Journ., 
 1896, vol. 2, p. 918. 
 
 165. Eobson, Mayo. A Case in which the Spinal Cord of a Babbit was successfully 
 
 used as a Graft in the Median Nerve of a Man. Brit. Med. Journ,, 1896, 
 vol. 2, p. 1312. 
 
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DR. R. KENNEDY ON THE REGENERATION OF NERVES. 2^7 
 
 Explanation of Plates 4-9. 
 
 PLATE 4. 
 
 Fig. I. Hands of Case I., before operation. Suture of median and ulnar nerves six- 
 and-a-half months after division. Sound hand for comparison. Shows 
 diffei-ence in quality of skin, loss of flexures, atrophy, sore on inner side of 
 lirst internode of little finger, transverse depressed lines on nails, and the 
 characteristic attitude. ^ nat. size. 
 
 Fio-. 2. Hand of Case I., before operation. Lateral view. Shows position in which 
 the hand was carried at the wrist, lines on nail of thumb, atrophy of thenar 
 eminence, and part of the cutaneous cicatrix from wound in forearm. 
 
 ^ nat. size. 
 
 PLATE .5. 
 
 Fig. 1. Hand of Case IL, with left hand for comparison, one year after operation of 
 suture of the median three months after division. Shows restored thenar 
 eminence and extent to which hand can be opened, f nat. size. 
 
 Fig. 2. Same. Shows extent to which hand can be closed. The inability to bring 
 the tips of the index and middle fingers by complete flexion of their terminal 
 phalanges into the centre of the palm is displayed. Operation cicatrix 
 shown in middle line above Avrist. f nat. size. 
 
 Fig. 3. Hand of Case IV., before operation. Section of ulnar nerve of eighteen 
 months' standing. Shows over- extension of the first phalanges and flexion 
 of the second and third phalanges of the little and ring fingers, and the 
 atrophy of the hypothenar eminence. The transverse cicatrix of wound 
 above wrist is shown, -g- nat. size. 
 
 PLATE 6. 
 
 Fig. I. Hand of Case III., with right hand for comparison, before operation. Two 
 months after fracture at elbow joint. Shows position in which fingers and 
 thumb were carried, and the atrophy of the thenar and hypothenar 
 eminences. ^ nat. size. 
 
 Fig. 2. Same. Shows hollowing out of palm and flexion at wrist, f nat size. 
 
 PLATE 7. 
 
 Fig. 1. Longitudinal section central bulb, ulnar nerve. Case I. Near centre three 
 small bundles grouped together, and separated by layers of connective 
 
 MDCCCXCVII. — B. 2 Q 
 
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298 DR. R. KENNEDY ON THE REGENERATION OF NERVES. 
 
 tissue, and each containing an enormous number of young nerve fibres, in 
 which are displayed the axis-cyhnders, each surrounded by a clear zone. A 
 bundle also shown longitudinally, the fibres showing in parts the delicate 
 axis-cylinder with granular deposit of myeline around, and also oval nuclei. 
 Zeiss, Obj. D. ^^. Cf. figs. 2 and 3. 
 
 Fig. 2. Longitudinal section bulb from peripheral end of ulnar. Case T. Shows 
 young nerve fibres identical in appearance with those in central bulb (fig. 1). 
 Many nerve fibres in ea^ch bundle. Distinct axis-cylinders. The nuclei in 
 the bundles are distinct from the nerve fibres. Zeiss, Obj. D. -^-f^. 
 C/.fig. 4. 
 
 Fig. 3. Same as in fig. 1. (Central end.) Part of largest bundle taking an oblique 
 course. Zeiss, Obj. F. ' ^^. 
 
 Fig. 4. Same as in fig. 2. (Peripheral end.) Shows young nerve fibres with axis- 
 cylinders and clear surrounding zone, and many nuclei interspersed among 
 fibres. Zeiss, Obj. F. ^^. 
 
 Fig. 5. Longitudinal section ulnar nerve at entrance to central bulb. Case I. 
 ; Transition from old to young nerve fibres. Shows old fibre diminishing and 
 
 giving place to young nerve fibres with spindle-shaped nuclei. At one side 
 a bundle of ^^oung nerve fibres Jess than double the diameter of an old fibre, 
 showing young nerve fibres with axis- cylinders, gi-anular myeline deposit, 
 and spindle-shaped nuclei, attached to sides of young fibres. Zeiss, 
 Obj. F. ^^. 
 
 PLATE 8. 
 
 Fig. 1. Transverse section of ulnar nerve eighteen months divided, immediately 
 proximal to the bulb on central end. Case IV. Portion of fasciculus. 
 Shows normal perineurium and small bundles of young nerve fibres arranged 
 like single old fibres. In some a deKcate sheath surrounding the bundle. 
 Zeiss, Obj. D. ^^. 
 
 Fig. 2. Transverse section, base of cone from peripheral end of ulnar, eighteen 
 months divided. Case IV. Shows compact tissue with small bundles of 
 young nerve fibres cut transversely. Nuclei in the bundles besides nerve 
 fibres. Zeiss, Obj. D. Sl^K 
 
 Fig. 3. Transverse section, proximal end of intercalary segment uniting ends of 
 median. Case I. Dense groundwork of fibrous tissue containing in its 
 meshes bundles of young nerve fibres showing nuclei. Zeiss, Obj. D. ^^S-. 
 
 Fig. 4. Transverse section, distal end of same intercalary segment. Dense masses of 
 fibrous tissue with a few bundles of transversely-cut young nerve fibres, 
 and one bundle of young nerve fibres longitudinally cut. Zeiss' 
 Obj. D. ^^. 
 
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DR. R. KENNEDY ON THE REGENERATION OF NERVES, 299 
 
 Pig. 5. Longitudinal (radial) section same intercalary segment. A portion at centre 
 
 of mass. Shows several bundles of young nerve fibres transversely cut. 
 
 Zeiss, Obj. F. a.Qo_ 
 Fig. 6. Another portion same section. Also at centre of mass. A bundle of young 
 
 nerve fibres seen longitudinally. Shows axis-cylinders and commencing 
 
 myeline deposit. Zeiss, Obj. F. ^^. 
 
 PLATE 9. 
 
 Fig. 1. Transverse section, intercalary segment — distal end. Another part of same 
 section shown in Plate 8, fig. 4. Shows numerous very small bundles of 
 young nerve fibres. Zeiss, Obj. D. -f-. 
 
 Fig. 2. Transverse section, proximal end of portion excised from median nerve. 
 Case III. Nerve compressed at seat of fracture. Shows old myeline nerve 
 fibres. Same appearance as section of normal nerve treated by same 
 methods. Zeiss, Obj. D. ^f^. 
 
 Fig. 3. Transverse section, distal end of same portion of nerve. Shows normal 
 perineurium, and small bundles of young nerve fibres, grouped as the single 
 old fibres in fig. 2. Many of the bundles contain also nuclei and are 
 surrounded by a delicate sheath. Zeiss, Obj. D. -j-- 
 
 Fig. 4. Longitudinal section through point of transition from old to young nerve 
 fibres in portion removed from musculo-spiral nerve. Case III. Two 
 old fibres are seen terminating and giving place each to a bundle of young 
 nerve fibres. Zeiss, Obj. F. ^^y-. 
 
 Fig. 5. Transverse section same. Near centre, two very large old fibres, one of 
 which shows at one side a slight thickening representing the nucleus and 
 protoplasm of the sheath of Schwann, while the other shows at one side 
 a large circular nucleus with two young nerve fibres at its side, all three 
 structures lying between the myeline sheath and sheath of Schwann. 
 Zeiss, Obj. F. ^^. 
 
 Fig. 6. Same section. Portion of perineurium, and near centre, a bundle of young 
 nerve fibres with two nuclei and the old myeline sheath and axis-cylinder 
 at one side. Zeiss, Obj. F. ^^. 
 Fig. 7. Same section. Near centre a bundle of young nerve fibres, with remains of 
 old fibre at one side. Zeiss, Obj. F. ^^. 
 
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Kennedy. 
 
 Phil Trans. J897. '?>.Plaie 4. 
 
 Fig.l. 
 
 Fig 2. 
 
 R.Kennedy. Photo. 
 
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Emnedy. 
 
 Fig.l. 
 
 Phil Trans. J897. V>.Plaie 5. 
 
 Fig. 2 
 
 Fig- 3. 
 
 R.Kennedy Photo. 
 
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 Fig 1. 
 
 Phil. Trans. Xmi.'&.Plafe 6. 
 
 Fig. 2. 
 
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 PhiL Irans. ]897. B Plate 7. 
 
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Kennecty. 
 
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 Fig 4. 
 
 
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