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(AI.IFtlKNIA T II 1 S V I, U M K IS GRATKI TI.I.V AM) KKSI'KCTKILLV DKDIi ATKD l\' t ^'t .m ^^ ' \ PREFACE. I\ 1S!)7 ii sorii'S of articles wiis begini in the New York Medical .lournnl in which the attempt was made to present in as simple and concise a form as possible the main facts con- cerning the newer investigations into some phases of the anat- omy and physiology of the nervous system. These articles were continued at inter\als for two years, but the mass of ma- terial proved to be too great, and neurological publications increased so rapidly during this time that it soon became ob- vious that any ade(|uate presentation of the subject must exceed the limits which could be allotted to it in a medical journal. The publication of a volume was accordingly decided upon, the introductory chapters of which consist of the articles (re- vised and brought up to date) which have appeared in the New York Medical Journal. The body of the l)ook, however, deal- ing with the groups of neurones Avhose axones constitute the principal known tracts in the nervous system — centripetal, cen- trifugal, and associative — is now published for the first time. In the first part of the volume the newer conceptions of the histology of the central and peripheral nervous organs are reviewed. In the succeeding chapters the attempt has been made to : pply the neurone conception — that is, the cell doc- trine — as consistently as possible, in the explanation and de- scription of the complex architectonics of the nervous system. The term /icurouc is used throughout in the widest sense to mean a ct'll b('JoiKji)i series of drawings of transverse and horizontal sections through the nu'dulla, ])ons, anATnoU.,a.- A,, ^^__ I'rdckssk XIX. lN-.'.{t)llli TO.iY. . .„,., XX. ON Tl.K .,k.;knk.ii I't'lls I'ldiii vent nil lioi-ii of OX . ... 4 2. (icrlacli's iR't\\oi-k G U. ('oniicclioiis of dorsal and ventral roots of spinal c-ord accijrdint; to a discarded tiieory 8 4. (Jolgi cell of Type I 11 5. Goljjri cell of Type II from cerebellum of rat 115 C. (iolgi <'ell of Type II from cerebrum of cat 14 7. Diffuse nerve network formerly supposed to be formed l>y the side fibrils of cell Type 1 and the axoues of cell Type II . .10 y. Longitudinal sagittal section of dorsal funiculus of cat fifteen days old 22 9. Transverse section of the spinal cord of a chick at the ninth day of incubation 2'{ 10. Schematic representation of dorsal funiculus cut longitudinally jiarallel to entrance of dorsal roots 24 11. Cross section of the cervical spinal cord of a child two years old, showing medulhited collaterals 25 12. lis. Cell intermediate in form between that of (iolgi cell Type I and that of (iolgi cell Tyi)e II 27.29 14. Nerve fibres from a frog injected with methylene blue . . .33 15. Sensory nerve ending stained with methylene blue . . . X] 16. Left luilt of brain ganglion of Merei.i dicersirolor with the nerves connected with it, seen from the dorsal surface . . .35 17. Scheme of lower motor neurone ....... 41 18. Cell from nucleus corporis trupozoidei of newboi'u cat, showing axones . 48 19. Cells from nucleus corporis trapezoidci ^f an adult rabbit . . 48 20. Cell from the nucleus corporis trapezoidei of an adult rabbit, showing axis cylinder 49 21. (ilomi ruins (dfactorius fi'oiu adult rabbit showing dendrites of mitral cells and terminals (•■ nervi'olfactorii .... 50 23. A portion of the molecular zone of the cerebellum from an adult rabbit showing terminal peridendritic axones .... 51 23. Motor-nerve spindle in longitudinal section of the right anterior nervo .stem from the leech 53 xi Xll TIIK NERVOUS SYSTEM. riOURB 24. Large (jluripnlar frnnglioii cell of the ventral paramedian field of the abiiuiiiiiiiil cord of LumbricuH 85. The plexus of iieuro-fibrils in some retinal cells of the third right eye of the leeeli 2G. A siibeiiidermal sen.«e cell, retinal cell from I'Keudo-brdiichellion 27. The distribution of the neuro-librils in the circular muscle fibre of tile intestinal wall of /'oii/olidr/ld .... 28. Colossal ganglion cell ('i'y]ie Ci) from the leech 29. Three jjear-shaped ganglion cells of Type K, in longitudimd sec tion, from the leech . 30. The course and connections of the conducting paths in a tran verse section of the somite of the leech .... 31. Spinal ganglioTi of a newborn white mouse .... 33. Motor cell of ventral horn of spinal cord from the human fa'tus thirty centimetres long 33. Pyramidal cell of cerebral cortex of mouse .... 34. Multipolar nerve cell from t lie cord of the embryo calf showing varicosities of the dendrites 35. Neurones from the hippocampus of a puppy two days old 36. Unijiolar cell from a ganglion of Luiiidricufi .... 37. Photomicrograph of a normal pyramidal cell from the cerebral cortex of a guinea-pig 38. Photomicrograj)h of a normal Purkinje cell from the human cere- bellar cortex 39. Photomicrograi)h of the apical dendrite of a large pyramidal eel of the cerebral cortex showing the arrangement of the latera buds or gemraules 40. Neurone from the optic lobe of the embryo chick . 41. Golgi cell of Type II from the dorsal horn of the gray matter o the spinal cord of tlie newborn mouse .... 42. Special cells ([loiyaxones) of molecular layer of cerel)ral cortex o a dog one ilay old 48. Ramon y Cajal's cell from the suiierfuial layer of the cerebra cortex of a fo'tal cat 44. Nerve elements from the retina of the ox ... . 45. Anax(>ne from the basket of a Purkinje cell of the cerebellar cortex 46. Y-shaped division of sensory root fibres afti.'r entrance into spinal cord in a six-months human embryo 47. End ramifications forming a basketwork about two Purkinje cells of the cerebellar cortex 48. The relations in the olfactory glomeruli of the axones of the olfactory neurones of the first order to the dendrites of the mitral cells in birds 49. Nucleus of termination of the sensory part of the nervus trigemi- nus of the cat 50. A much-branched fibre from the ojitic thalamus of a mouse . PAOI 54 55 55 56 57 59 61 68 69 70 71 73 74 74 75 76 79 80 81 81 82 82 83 83 84 84 85 LIST OF ILLUSTUATIONS. XIU FIOrUB I'AdR 51. Three ciul arborizations of optic fibres from the optie lobe of an embryo cliieit HO 52. The so-called "eliinbiiifj fibres" of tlie cerehellar cortex from the brain of a child n month and a half old 87 53. Disc-shaped expansions on nerve fibrillie of the pig's snont and their relation to certain of the epithelial (.'ells . . . . S7 54. Developing myelin sheaths of diflerent ages as seen through the polarization mi'jroscope SH 55. Scheme showing the elements of the gray matter of the spina' cord 91 56. Endings of collaterals from the dorsal fnniculi in the gray mutter of the spinal cord of the newborn ral)bit 92 57. Side fibril of (Jolgi on the axone of a motor cell of tlie ventral horn of the spinal cord 93 58. Pcrice'hdar networks believed by Held to be formed by tlie termi- nals of uxones 95 59. Reproduction of a photograin of a perpendicular section through the tip of the head of the gyrus centralis anterior of a healthy adult man close to the falx 97 60. Reproduction of a (ih gram from a perpendicular cortical sec- tion through the summit of the gyrus just in front of the sulcus cruciatus of an adult dog close to the falx ... 98 61. Reproduction of a photogram of a perpendicular section through the cerebral cortex of a mole, 1 mm. in front of the crucial suture close to the falx 99 62. Ganglion cell from the electric lobe of the brain of the torjiedo . 103 63. Xerve cell from the region of the ventral column of gray matter of the spinal cord of C'ddu.'i 105 64. Large motor ganglion cell from the ventral horn of spinal cord of ox 109 65. Spinal ganglion cell from the ox showing clear spaces ( Vacuolen) 112 66. Spinal ganglion cell of liana Catesbiana 113 67. Nerve cell from olfactory bulb of rabbit 116 68. Nerve cell from dorsal nucleus of proximal portion of medulla of rabbit 117 69. Motor nerve cell from ventral horn of gray matter of spinal cord of rabbit 118 70. Large cell from Ammon's horn of rabbit 119 71. Nerve cell from ganglion on dorsal root of a cervical nerve of a rabbit 110 72. Purkinje cell from the cerebellar cortex of the rabbit . . . 120 7o. Nerve cell from the spinal cord of the dog in the so-called "chromophiie" condition 124 74. Motor nerve cell from the ventral horn of the gray matter of the spinal cord of the dog showing tigroid bodies .... 125 7"). Cell of ventral horn of gray matter of human spinal cord . . 130 76. Nerve cell from Deiters' nucleus in the rabbit .... 131 m xiv TIIK Ni;itVOL'« SYSTEM. KUit'KE PAOIt 77. Nerve cell from the gray inatler (if the luiiil)ar ( onl (if fix . . 138 78. The eiKlocelluiur network within a i'lirkinje cell . M('(lian section tlir(ii!:,di eml)ryo human brain at the end of the first montl 160 90. Jlodel of (levelii|'ing human brain 161 91. ]\Iedian section o ftal luinnin brain during the third month . 162 92. Median sectidii thii'iigh adult human brain 162 93. Section through medidlary plate of rabbit showing germinal cell . 165 94. Section through neui'al tube which is beginning to close . . 165 95. Section thi'ough wall (if neural tube at a later stage . . . 166 06. Photomierograiih from a specimen through the neural tube of A)nh/i/s/(>iiut 168 97. Section of spinal coi'd df a chick at the third day df incubation . 169 98. Section through half of neural tube showing the pear-shaped neuroblasts 171 99. Transverse .section of the spinal cord (if a chick .... 173 100. Transverse .section through the upper tlioracic cord of the human embryo 173 101. Commissural cell or heteromeric neiu'one from the spinal cord of a l'riti/iiiriif< embryo 30 mm. long 174 103, 103. Transverse section through the medulla of the human em- bryo showing N. liypoglossus, N. vagus, and tractus soli- taries 174, 175 104. Section through i portion of the wall df the medulla df a human embryo showing ncnroiilasts wandering from the rlidmboidal lip tdward the middle line 176 LIST OF ILIA'STKATIONS. XV KKil'RE 105. tSeheiuo of one half of llie (;inl)r}oiii(: iiu'diillii at u later stage 106. Transverse section tlirougli one lialf of tlie niedtillu obloiigtita of u hiiiiian criihryo at tlie eiglitli iiumtli ..... 107. Longiliuliiial section of liie cerebral hemispheres of ^\fi!uri(.s 108. Reconstruction of human einhryo ut end of fourth week showing development of sensory ganglia 109. Three stages of develoimient in the early history of the spinal ganglia of the Innnan embryo 110. Transverse section of tlie emhryoiui; conl of the cldck . 111. I5ipoiar cell from the spinal ganglion of th<' pike . . . . 112. Bipolar ganglion cell from the ganglion spirale of the pig 113. Schematic re|)resenlation of the gradual transition nf tiie bipolar cells of the s|)inal ganglia to the so-called unipolar type 114. Transformation of bipolar cells into tmipolar cells in the(iasserian gangli(jn of the pig 115. Feltwork about spinal ganglion cells of thecal formed by division of the axones of spinal ganglion cells of Type 11 116. Scheme of the reciprocal relations of the elements within the spinal ganglion, according to Dogiel 117. Left auditory vesicle with the acustico-facial complex of a tuiman endiryo at the fifth week lly. (•phthalnn(! vesicle showing stalk and groove in stalk from a human embryo of the fourth week, seen from below 110. Develo|iing eye of human embryo 10.3 mm. l.»ng . . . . 120. Composite diagrammatic transverse section of the head of a human embryo to show the growing point in the nervous system, ami the direction of the growth of the til)rc 121. Transver.se section through the anterior |)art of the trunk of an embryo of Sci/lliinn 123. Photomicrograph of section through a nerve in the side of a human tongue 123. Schematic representation of I lie nerve plexus of a heart of a human embryo after His .Ir 124. Diagram showing successive positions of the diai)liragui during the development of the human embryo 125. Schemes of transverse .sections of younger and iildcr Selachian embryos to illustrate the development of the chief pn.ducts of the middle terminal layer . 126. Fluman embryo fourteen to sixteen days (dd showing devcdoping myotome 127. Human embryo at the end of the third week .showing developing myotome and sclerotome 128. Scheme of bone and muscle segment 129. Trinik segment of human embryo with oni' pair of iicr'ves and the rudiment of the musculature of (nie extremity at the sixth week 130. Reconstruction of a young human embryo enlarged five times, I'AOK 170 177 178 IHO ISl 182 182 182 183 1H3 184 185 186 187 187 188 189 li)() 191 194 196 197 I i! 198 199 200 j^ttgajjOf^ XVI THK NERVOUS SYSTEM. I FIOITRE PAOI illustratiiif,' the positiDti of the M. rectus alxlominis and its |)i)lyiiicric riaturi' 202 181. Fields on the extoriml surfiiee of the os iiiiioiiiimitum corresi)oii(l- iiij; to tiie attfichiiieni of the viiriims iiuist'les .... 203 132. Outer surface of os itinnniinrtltim showing attachments of the muscle masses derived from the myotomes innervated by the twelfth to the nineteenth thoraco-lumbo-sacral nerves . . 204 133. Reconstructed form of pelvi of human fo'tus, illustrating skeletal areas corn'sjiimding to the myotomes innervated by tlie 12th to the nineteenth thoraco-lumho-sacral nerves . . , 205 134. Arrangement of the meta/onal dursal nerves for the Mm. glutaM 207 135. Arrangement of the nu;tazonal ventral nerves for the Mm.fl'^xores 207 130. Arrangement of the prozomil dorsal X. femoralis .... 208 137. Arrangement of the diazonal ventral N. < '-turatorius . . . 209 138. Arrangement of the ventral and dorsal prozonal, diazonal, and metazonal nerves 210 139. Six transverse sections through a right upper arm showing the relatioa of the (dark) ventroplanum to the (colorless) dorso- planum, as well us the position of the fourth to the sixth cervical sclerozones 211 140. Transverse section through the musculature of the shoulder and che^t showing the limits between ventral and dorsal deriva- tives of the myomeres 212 141. Transverse section through the proximal portion of the humerus . 213 142. Transverse section through the distal part of the humerus . . 213 143. Wallerian degeneration of nerve fibres after section . . . 224 144. Section through the cervical cord of a woman showing secondary degenerations following compression of the cord at the level of the second thoracic segment 226 145. Section through the lumbar cord of a woman showing secondary degenerations following compression of the cord at the level of the second thoracic segment 227 146. Section through human spinal cord in the ui)per thoracic region showing marko'? atrojihyof right half of cord following ampu- tation of right .'m 230 147. Transverse section through the medulla oblongata of a rabbit showing degeneration from injury to facial nerve on the right side 232 148. Cross section through the medulla oblongata of a rabbit showing degeneration from injury to facial nerve on left side . . 233 149. Cells from the nuclei of the oculomotor nerves of the eat thir- teen days after section of the root fibres of the nerve on one side 235 150. Pour nerve cells from the nucleus nervi facialis of a rabbit fifteen days after section of the nerve root 236 151. Ventral horn cells from the spinal cord of a case of multiple neuritis 237 LIST (»!• ILLUSTIIATIONVS. xvii KKll'RK PAdK 153. Nerve cell from cerebral cortex of dog showin;; ullerutioiis phicdy ii; llif (Icndritcs tiiriit'il toward 11 llii'oiiiliuscd vessel , . 2158 153. Ijiirger pyruiiiidfd cflls fnuii tiie sccuiid lavcr of the cerebral cor- tex siiowing advanced staf^es of degeneration rullowing ricin poisoning of fourteen iioiirs' iliirat ion 239 154. Slronj; aiiieal (I'Midrilesof jiyi^aniidal cells I'nuii llie iniinan cere- bral cortex 240 155. Frontal section tlirough the niesencejilialon siiowing vascnliir supply 243 l.jd. Caryocinetic figures in nerve cells in brain of dog three days after introduction of foreign body 24? 157. Scheuie s produced in cell bodies of lower motor neu- rones (1) by cutting the axonc and (2) by cutting the corre- sponding dorsal roots 298 1 XVIIl TIIK NKKVOUS SYSTKM. 'il ■^i4 KKH'IIK I'AdK 17M. lOITcc'ts of |)oisoiiiiip with iimloii-iiitril ;K)(( 17!». I'llTccIs (if arliliciiil iiicr('ii."-c of body tfrii|iiialur(' .... 1501 1H(1. Iiccovcrv of vciitiiil lioni ci'll from clmiijiis |irotliici'(l by artificial increase of liody t('in|ii'nittire IJOIJ ISl. i'KTects of tetanus Idxiiie upon t lie lower motor iieiiroiics . . ;{(J4 IH'J. Moi'c advanceil staj^es of poisoninj; witli letaiius loxine , . iJ05 18;{. .Spiiuil fjanj^lioii cell showing inarked alterations following section lis 359 211. Nerve fibrils in the epithelial lining of the (rsophagus . . . 362 212. Nerve fibrils in the epithelium of a vertical section of the rabbit's bladder 363 23(1. 2;i7. 238. 239. 240. 241. 242. 243. 244. 245. LIST (»F II.I.I'STKATIONS. XI. \ KKll'l 214. 215. 21«, •JIH. 'ilU. 231. 323. 334. 32r). 336. 327. 33H. 22!). 3;i(). 3;{i. 3:52. 233. 234. 235. 230. 237. 238. 23!». 240. 241. 243. 243. 244. 345. 'rcrriiiniitiiiii in \\w form i>r in-roil I'liil pliililcls (ni tlic <'iliuti'(l ccllh tif llic t'nin's [mlaic ;{(>;{ Vcrliciil section tliidti^'li the ciinu'ii ;5(t4 'i'raiisvcrsc si'i'tiDii tiirou).'li till' skin nf the t ar of ii wliitc inuiise lliri'o (lays ohl 317. Norvcs and ni'i'vi' cndin^^s ill tlio hiinmn cornea . . ;i(((i, jMecliillated nerve lil)ro from the conjnnctiva of man Nervi! endings in epitlu'liuin of frojj's palate A (perpendicular section of the lower part, of the epidermis lie- t\V(!en two papilla- which shows a lar^'e f,'rou|) of Merkel's Taslzel/rn A perpendicular section lliroufjjii tiie lower part of tiic epidernds lietween two papilhe. from a fu'tus 3(» em. lonj;, to show the development of liie nerve endinjis alioiil Merkei"s Tdufzvlltn . (irandry's ternnnal nerve corpuscles from the duck's liili Flat prc|iuration from the mucous mendiranc of the palate of a duck showing nerve lUires and nerve endings . Tactile discs from two Cirundry'.s corpuscles in connection with the axis cylinders of the nerve fibrils connected with tiicin . Nerve endiufjs about a large hair troni the dog .... Krectile body of a hair of the rat Nerves and nerve endings in the skin and hair lollicles. N(U've endings in the form of tactilediscs beneath the glassy mem- brane of the liaiis Longitudinal view of tooth of (inliiiiK showing nerve terminals Nerve endings in the liver Periacinous plexus of nerve fibrils in the pancreas. Nerve cells and nerve fibres in tlir villi and among the triaiids of the iiitcstinuin teiiiie of the guinea-jiig Nerve endings in the salivary glands ...... Section through the caput e|)iilidymidis of a young tomcat . Nerv(! terminals .n t''ansver.se section of the tiibuli .seminiferi of the rabbit ;{80 Nerv(\ endings in the mammary ghiiid 381 Two corpuscles containing nerve endings from t lie external con- nective-tissue sheath of the dog's prostate .... 383 Free nerve endings in the basal inembrane at the junction of the epidermis with the siiiicutaneous tissue ..... 383 Tactile corpuscle of Meissncr from a section through the skin of the human toe .......... 384 Section through the skin of the too 385 IMcissner's corpuscle .......... 385 Tactile corinisde from the skin of the volar surface of the index finger of a man twenty-five years olil 386 Peri[ilieral jwirt of conjunctiva palpebrarum of man . . . 387 Terminal nerve corpuscles in the eyelids of man .... 387 Semi-scheiratic section of the skin of the [uilp of the fingers in 3((4 367 368 :!6!) 369 369 370 371 373 373 373 375 376 376 377 378 379 380 380 m <«> XX THE NKUVOUS SYSTKM. Ill, KIllUliB l-AIIK order 1 1) (leniDiist rale tlic !ii|)nj;rii|iliy of L'ulllni's "icrmiiiiil iicrvDiis niijiiris " ;IHH 240. HiiHiiii's iitMVf cmliiij^s ;iN|) 247. Tcnniiml nerve (•(ir|iiis('lc of IJiiniiii :i!i() 248. 'rraiisverse seel iiiii oT liiilliiii's teriiiiiml (■f>r|piiscle . . . . ."(id 24!t. ()l)li(|iie seel idii (if ii Icriiiiiijil iii'ivc i(ii|)u.sc|i' of liiillini . . :i!M 2.'5(l. A nerve lilire ilividiiij,' into si^veii seeuiidury liWres lo wliicli are atlaclicil {\\v iiii/inir.s iii'rriN.r /I'niiiii/iii.riif Ifulliiii . . ;!!I2 2')!. Hnd hiillis slaineil liy llie iiielliylene-liliie inelliod .... '.W.i 232. 'I'erriiiiial ciiriuiscle lioiti iln' lilire "f tlie iinijiiiKl i\M ludlii . . ;}!);{ 2r).'{. Ilerl)sl's ec)|-piisi les ;{!)4 254. ('()r|)iisel(< of Pacini of the niesoiitery of an adnlt cat . . . ;()(.'» '■i'hK Oolj^i-Mazzoni corpuscles ;{!)7 25(5. (lenital nerve coi'|)nscles fi'oin file iniicoiis mendirane of the cli- toris of tiie ral.iiit :i!»H 257. (iunital nerve corpuscles from tlie nuic2. A brunch of one of the anterior nerve filii'cs of the cornea . . 40;{ 26;J. ."Musculo-tendiiious nerve ending' of (iol;;:! ..... 404 2fi4. Tendinous expansion of oi'e of the muscles of man . . . 40G 205. A terminal niuseulo-tendinous organ in which a terminal nei've ])la(pi(> occupies nearly the length of the tendon . . . 407 2C0. Human tendo calcani'us (Achillis) 408 2(57. Tendinous expansion of one of the motor muscles of the eye of an ox 40!) 268. A .sensory nerve ending froin exocardium of ujipei' half of left atrium of the heart of the gi-ay rat 410 2(5i). Nerve endings in the lung of the frog 411 270. S(^nsory nerve cndiniTs in the ciliary body of birds. . . . 412 271. Nerve endings in ciliary body demonstrated by the method of Golgi 41!} 272. Muscular spindle from .Ui/fi.rns ((rcll\v of cardiac muscle cells with nerve endings . . 41!) 277. intermuscular end arborization from the left wall of tlu^ trachea of the (log 420 278. Ijongitudiiiid section of involuntary muscle showing nerve end- ings 420 27!). Nerve ending on the vas afferens in the cortex of the kidney . 421 ''lif IJST OF ILIA'STUATIONS. xxi KIOfKB I'AliK 2H0. Fiftures illust nit ing flic dorsal fiiniculi in tin- cervical, tlidriicic, ami liiniliiir rc;,'i()iis 111' t he >|iiiial conl ..... 4'M 'J81. L'p|)cr half of liiiiiliar cnlargcincni of u ficliis li.") cm. loiif; . . 4!Jb SH'J. t'ross scftion through the sjiimil t-ord at the level of t lie third liiiii- liar iiervi) 421) J8;{-!i90. Tliu lilirc sysfoiii.s in the spinal cord of the f(ctus . . 4;il-4U4 291. Tho nerve tracts in u case of lnnil)ar tabes (Trepinski) . . . 4U0 2i)2. .Secondary dee;cnciiil inns in the spinal cord lifter exiierimental sec- tion id' dorsal roots 440 'jyJJ. Transverse section of the hnman spinal cord showing sccondai'V degenerations following isolated loion of the sixth thoracii; spinal nerve .......... 445 294. Seliomc of the course and tcrndnation of the fibres of the dorsal roots 448 295. Secondary degeiuTalion in the dorsal funiculi Itclow a transverse lesion due to compression of the cord 449 296. lioiigitudinal section in an almijsl sagittal direction at the level of tlu! eighth thoracic nerve showing degenerated lllu'cs in ihe dorsal funiculi after transverse lesion .... 451 397. Descending degeneration below a transverse lesion at the level of the seventh thoracic segment 454 298. Descending degenerations below a lesion (compression) of the spinal cord at- the level of the eighth cervical nerve . . 455 299. Sagittal longitudinal section at the level of the fifth sacrtil nerve from a ease of compression of the cord at the level of r. viii 450 300. Cross section tiirough the spinal cord of a rabbit eleven days after compression of the aorta for one hour 460 301. Transverse section through the medulla oblongata in the region of the decussatio leinniscornm ....... 402 302. Cross section through the medulla oblongata at the level of tlu^ lower half of the nucleus olivaris inferior .... 402 303. pjutrnnce of tlie fil)res of the dorsal roots into the dorsal funiculus of the spinal cord of an embryo calf 467 304. Scheme indicating tlio course followed by the central axones of the peripheral spinal centripetal neurones in the dorsal funic- uli of the spinal cord 469 305. Cross section through the spinal cord of a newborn babe, to show the collaterals 471 306. Scheme of the structure of the spinal cord 472 3(t7. The developing cerebral norvos 478 308. Transverse section through medulla oblongata of newborn child at level of decussatio lemniscorum 479 309. Transverse section of medulla oblongata of newborn child passing through the nucleus olivaris inferior 479 310. Transverse section of the medulla oblongata and cerebellum of new-born child showing nucleus dentatus .... 480 t 4 '■^n XXII TIIK NKIIVOUS SYS'I'KM. KIOI'HK VM* lilt. 'rnuiMVorsc sect ion (liroii^h tin' iih-iIiiIIk i>l)Ii)iipilii iinil (')'r(>lu>IIuiii of iii'wiioni chilli ; ic;;ioiM>r coclili'iir iiiicitM , . . . IHl 312. TratiHV(>r.si>s(M'lii>ii liiroii^'ii tlir i'iti'IicIIiiiii aiiij iiiciluliii ohjori^utit lit tlif jiiiicl ion r>r the liiltt'i' will) the pons .... 4H2 31S. 'rriinsvi-rst! sfciior, tliroiijjli lln' poiijs ant! corchclluni at tin- level of the in'iiK'ipal motor nntleus (if the Irip'iiiiiml nerve . 4H',\ UM. Transverse section throiij^h the islhinuH rhoinbuiicopiiali oC new- born lialie 184 315. 'I'ransverse section at the level of the collicr.lns inferior of cor- pora i|iiailrip inina of newliorn lialie 4H.'5 KHi. Transverse sect ion through inesencephalon of newliorn lialie: level of superior i-olliculiis 4Htt HIT. Transverse section thmiiyh superior collicnli ami cereliral pe- (Inncle of newliorn halie |H7 31H, 310. Horizontal section thmui^h meilulla, |ions, and niiillirain of newliorn lialie; level of nucleus iiervi aliiliicentis , 4HM, 4S9 ti^O. nori/m axoiics of (lie iiorvi vcsti- liiili ill llic iiiu'lciis iifi-vi M'.'liliiili l"t('ruli> .... 't\'.i 'MO. (iiin^lioti Ki'iiii'uli of iifwiMirn inoiisi' .'ti:) ;(-l(>. N't'iitral view of ccrclinim with |porlioii of spinal ccinl . . . "il.") ;t4t. 'rruiisvcrsc .srctioii llin)ii;,'li the |ioii.s and ct'i-i'lii'lliiiii ut ilii- li>V(>l of till) |iriii('i|)iil motor nucleus of llir tri^i-miiml nerve "ilO 342. Sclieine of motor ami .leiisury iH'iiroin's, ihc iixoiies of wliicli enter into the formation of \. IriKemiiuis 517 348. liiiteral !lonj,'atit at. level of caudal I'nd encephalon of monkey after de- struction of nucleus funiculi cuueati and of corpus resti- forme . 380. Ti'ansverst' sections through posterior half of pons and through midbrain 387. Cross sections thnuigh hum.in spinal cord 388. Nerve cell from nucleus dorsalis, hunuin emliryo .... 389. Frontal section at junction of pars thoraealis and pars lunibalis of spinal cord 3f)0. Transverse section through ]>ars eerviealis of llu' cord . 3itl. Transverse seetion through u|)per third of medulla oblongata of huinan fu'tiis 3!>2. Frontal section of medulla oiilongata and cerebellum of seven months' f(et us; level of nucleus vestil)uli .... 3!(;i. Frontal section of nu'dulla oblongata and cereliellum of seven months' fo'tus at the level of inicleus dentatus 3!)-l. Frontal section through rhombeiu'cphalon of monkey after de- struction of niu'kus funiculi cinieati and corpus resliforme . 3i)r). Transverse section of spin.il cord at the level of fourth, cervical segment !o show degeneration of (iowers" tract 3!)6. Scheme of c(-ursp of I'lbre:-, of the two principal tracts from spinal cord to cerebellum 307. Degeneration of (iowers' tract above nu'dul la oblongata 398. Ascending (^.egcneration of (towers' tract 3)(!(. Central sensory conduction ]ialhs in the spiiuil cord 400. 'i'automeric, beteroineric. and hecaferomeric neurones in pars lumbalis of human spinal c(U'd 401. Transverse section through |iosterior part of pons . r>,-)9 ntio r>()i rm ."•)(;(> ;-)(i7 571 572 573 574 578 582 583 584 585 596 588 589 591 593 595 596 ()05 607 CIO 424 434. LIST (»F ILI.rsTUA'l'loNS. x\v KIOrnE TAfiK AU2. Soctioii tlironf,'!) iiii'diillii (il)l(iii(,'iitii iit Icvi'l of N. vtijjiis ninl \. liypiif;li)ssiis (ilv; <((•;(. Sffliciii llii'(iiij,'li Micdulla oli|1' root nl' N. f,'l(isM.- |iliiiryiif^('iis (»i;J 404. Cross ^itM•li()n tlirinif;li i^llmiiis rliiiiiilieii(e|)iiiili .... ^\\^^ 405. Simic as Fij;. :m 01(5 400. Sn^ittiil section of ineiliillii, |ioiis, iiikI inidln'iiin in eliilil iii;eil tlirei- iiioiillis 017 407. Same as I''i;;. IJi.'.') O'J'2 40H. Set'lioii tliroiij;li nucleus alii' ciiicreii' in <'liil(l six weeks old . . 02!J 40!). Same as Kij;-. ;!2!t O'.M 410. Transverse .sccl ion oT medulla tliroui,di nucleus comniissuralis . O'Jo 411. Same as Kifj. ;{;tr> 02H 412. Section through rhoinlicnet'|ihalon helow the fjcnu internum radicis N. facialis (U!) 41i{. Frontal section through jions, sliowing Dcitcrs" unil Hechterew's nuclei in newliorn mouse OHO 414. Same as Fig. ;{ir> 0;il 415. Same as Fig. :{2;5 0;5;5 416. Same as Fig. ;!12 6;J4 417. Transverse .section tlirough rliond>en(.'ephalon of mouse showing Deiters' nucleus fi;{5 418. Obli(iue section through brain stciTi ol' newitorn cat showing imth from l>eiLcrs' nucleus to the cord GliO 41!). Transverse section through Deiters' nucleus in the mouse . . {u]S 420. Horizontal section thr-mgh medulla, pons, and midlii'ain of new- liorn babe, level of decussatio brachii conjunct ivi and nucleus reticularis tegmenti 6;{!) 421. Same as Fig. ;i4(> 043 422. Transver.se section through brain stem of young rat showing de- cussation from t lie nuclei N. trigemini 045 423. Horizontal section of cerebellum showing marginal thickenings of the lingula 048 424. Transverse .section through ceri'bcllum and nu'dulla of human endiryo showing nucleus (l.'iitat us 04!) 42.'). Same as Fig. ;il() 050 420. Same as Fig. ;il4 051 427. Same as Fig. tilH 0.53 428. .Stilling's large and sMuill "scissors" of the brain .... 053 42!). Same as Fig. liUi «54 430. Same as Fig. 420 056 431. Same as i'Mg. 404 658 433. Same as Fig. 3H(i 000 433. Frontal s(>ction through corcibellum and pons of fo'tal mouse showing N. trigeminus (i03 434. Lateral sagittal section through jions and cerebellum of fict.il mouse showing sensory part of X. trigemiinis . . . . 003 & XXVI THE NEItVOUS SYSTEM. I I FIOURK PAOB 43.'). Transverse section throuj^li middle of sii[)erior colliculus . . (iti!) 436. Frontal section tiirouf^li liunian brain stem showinii; I'^orel's Fc/d yy and till) I'orjms Lnjsi <)70 437. Frontal section tlirongli liypothalaniic rcfjion, luinniii lirain . 073 438. Frontal section through brain stem showinj^ Forel's Frld //, and //., 673 439. Frontal se.Mon through brain stt-in of man siiowing corpus Luysi ()7() 440. Frontal section ilu'ou^h decussalii) Ijrachii conjunctivi . . . OhJl 441. Frontal section through normal human brain at level of corpus goniculatum mediale 083 443. Frontal section through human brain at level of nucleus hypo- thalaniicHis . 083 443. Frontal section through human Inain at level of ansa lenticulu- ris 084 444. Frontal section through human brain at level of thalamus . . 685 445. Isthmus rhonibencephali in prolile ....... 087 440. Scheme of tlbi'es in superior colliculus ...... 688 447. Same as Fig. 37H 089 448. Same as Fig. 314 Oi)0 449. Same as Fig. 333 091 450. Sagittal section of babe's brain showing capsula interna . . 093 451. Same as preceding 093 453. Same as !''ig. 310 095 453. Same as Fig. 333 096 454. Schemes of course of lemniscus medialis ..... 098 455. Scheme of degeneration in a case of lioesel and Flechsig . . 703 456. Scheme of central paths 706 457. Degeneration after destruction of dorsal funiculi .... 710 458. Cortical area of termination of lemniscus filires in the cat . . 713 459. Same as l''ig. 400 719 400. Sagittal section through brain of In'tai mouse siiowing fa.sciculus longitudinalis 730 461. Same as Fig. 333 733 403. Same as Fig. 334 733 403. Same as Fig. 317 734 404. Same as Fig 409 738 405. Same as Fig. 413 739 460. .Sagittal section through human brain 735 467. Frontal section tlirougii human iu'ain 736 4()M. ilori/ontal section through human brain 737 409. 470. Scheme of general soma'sthctic paths .... 743, 744 471. Scheme of neurones superimposed in general soma'sthetic paths , 745 473. Scheme of relations of anterior and posterior olfactory lobes . 750 473. iJasal surface of human fu'tus. fifth month 751 474. Basal surface of lii'ain of man fiirty-thrc(> years old . . . 753 475. lihinecephalon of a man fcir'ty-lhi'ee years old .... 753 LIST OF ILIiUSTKATlONS. xxvii FiorRK I 47(5. Jjowcr |iiii't of {^yriis liip|»i('iiiiii)iis ....... 477. Inferior untprior extremity of f^ynis liipiiocmiipiis . 478. Frontal section of biill)iis olfactoriiis of yoiitig ral)l)il . 479. Transverse section of liiinuin 1mi11)iis oifactorius .... 480. Horizontal section tlirouf,'h l)nll)iis and tractus olfactoriiis of man 4H1. Mitral cells from nionse twenty-fonr days old .... 4H2. !{nli)iis olfactoriiis of mouse twenty-four days old .... 48;J. Same as Fij,'. liol . . 484. IJulhiis et lobus olfactoriiis of rai)l)it in liorizoiit a! section 48.'). Three olfactory ^^raniiles from a cat 48(5. Ventral |iarl of frontal section of ralihit's brain showinj; basal f,'inif,dion 487. Islands of pyramidal cells in tuljcrculiun olfactoriuin of rabbit . 488. One of C'allcja's islands in the olfactory tubercle of the rabbit 48!i. Section through base of lirain and hippocam])us .... 490. Cells from nucleus corporis maiiimillaris of a child ' Sagittal section tlirougii corpus niammillare of newborn mouse . : , Frontal section through iiiicleiis ruber and nucleus N. oculo- motorii of fcctal nioiisi' 4S)3. Oblique section through brain stem of cat four days old showing formatio reticularis 494. Oblique section through brain stem of cat four days old showing the decussatione.s tegmenti 495. Oblique section through brain stem of cat eleven days old showing origin of (ilires of fasciculus longitiidiiialis nicdialis 496. Transverse section tiirough tela chorioidea ventrieuli tertii . 497. Sagittal section of brain of a rabbit with bands of fibres in three planes 498. Golgi preparation from peduncular region of mouse 499. Diagram of Meynert's bundle .'iOO. Hori/ontal section of i)rain of C^/ypr/MHs crt/7»'o .... 501, 502. Principal neurone systems of olfactory conduction path. 779, 50:i. Nerve cells from the retina of the chick 504. Brains illustrating atrophy following removal of eye in newborn rabbit 505. Hemoval of left half of chiasma opticiim with the commissura inferior (Juddeni ill the ralibit ....... 506. Chiasma o|)ticum and tractus opticus ill liuiuan brain . 507. Scheme showing Ileiischen's investigations on relations of bundles in optic nerve, etc 508. Absence of optic chiasm 509. A ])()rtion of the right cereiiral hemisphere to illustrate the basis cereliri ........... 510. Frontal sections through corpus geniciilatuni iaterale of dog 511. Horizontal section through cerebral peduncle and hypothalamus. 512. Corpus geiiiculatiim laleviile of newborn cat ..... 513. I'ulvinar of mouse five davs old ■A<1K 753 754 756 757 758 759 760 761 762 763 764 765 766 767 769 770 771 773 776 777 777 778 780 785 787 788 789 794 795 797 79!) 801 802 803 i.i 11' '1 > ' I XXVIU TIIK NKRVOUS KV.STHM. ' ]\ Ml KKir 514. 515. 51(i. 517. 518. 519. m). 5'Jl. 5:.>;j. 5'24. 5:^5. 526. 527. 528, 52l». 5;iO. 531. 532. 5:J3. 534. 535. 53(i. 537. 538. 530. 540. 541. 542. 543. 544. 545. 54(). 547. 548. 549. TriinsviTsc scctidii (if iioriiijil liiitnan optic chiiisiii . Sfctiuii (if brjiiii of cliild tlircc inoiillis old sliowiiij; optic ciiiasiii . Uniiii of riiljliit aflci' I'cmoval of one eye and scmmhiicc of tracttis opticus Frontal section tliron;;!! liinnan liypotlialainu-- . . . . Frontal sc^ction tliroiif;li coiliculus su[i('rior of the raliljit Transverse .section through colliciilns .superior of rabbit Fi'ontal section tliroiii,'ii occipital lohc ...... l''rontal section of liunian l)rain illustrating' visual conduction path Frontal section of huuuiii brain iliustratinf; occipito-lhalaniic radiation Frontal section of iuniian brain illuslratinf,'occi|iito-tlialaniic radi- ation, etc Posterior |iart of left cercliral heniispliere, medial surface Horizontal section from brain of ciiild in second week of life Xorinal and defjencrated corfius genicuintuin lateralo . Frontal section through nucleus iialicnula' and tludamus of new- born mouse Section through cortex of the gyrus occipitalis superior Scheme of visual conduct ion paths . Scheme of hypotlu'tical decussation of axoucs from coi'|)Us geni(;u- latum laterale to lobus occipitalis Optic central paths illusti-ating von Monakow's view of represen- tation of the ri'tiua in the cortex Sciienie of optic [)aths illustrating cortical and subcoi-tical hemi- anopsia \'isual conduction jiath Visual conduction paths Section of brain stem of newborn cat illustrating the separation of the fasciculus longitudinalis from the fibre system from the colliculus superior to the ventro-hiteral funiculi and the relation of the lateral lemniscus to the colliculus inferior 'I'ransverse section of medulla ol)longata showing cochlear nuclei. Same as Fig. 313 Same as Fig. 323 Same as Fig. 314 Same as Fig. 440 Nucleus nervi cochlea' vcntralis of newborn cat . . . . Nuclei termimiles of nervns cochlea' of four-day-old rabliit . Cross section of pons showing imcleus nervi cochlea' vcntralis 'i'ransveise section through nucleus olivaris superior Terminals of axones in the nucleus corporis trapezoidei. ("ell from nucleus corporis trape/oidei of newborn cat . Cell from niu'leus corporis trapezoidei of adult ral)l)it . Transvt'rse section through corpus trapezoideum of newborn mouse ............ Nucleus semilunaris of newliorn cat I'lOK 80(1 806 807 808 810 811 813 814 815 816 817 818 819 820 822 824 825 827 82!) 833 834 838 842 844 845 846 847 848 850 853 855 856 857 858 8.")9 800 \ '■' ■ I! LIST OF lLLlS'riL\TI().NS. x.\i\ MOT Stj!) H70 871 873 874 870 877 878 87!) KKirnK I'AliK r)."»(). ('ill's brain lifter section of li'imiisciis lateralis .... Mfil .>")!. Trunsilion of eoi'[ius lra|ie/.()i(leuiii iiilo lemniscus lateiiilis . . HiV.i ,").■)•,'. Same as Fig. :jl4 805 'i'}'-]. 'I'l-aiisverse section of colliciilns infei'ior of eat .... 880 554. Termination of axoncs of nerviis cochlea' in t lie central nei'vniis system ............ J).").!. N'ciiroiies with descending; axones in the central acoustic |)aths . ij.lO. Relations of leniiiiseus lateralis to corponi (|ua(lrigeiniiia 557. Optic and acoustic reflex ]iaths 558. ("orims traiiezoideiun in lirain of rahhit ...... 55!). Frontal section of human brain in which liiere was a lesion caus- inI.FSTUA'n()NS XXXI KKU'KB PAOB ((24. Sclu'iiic (if (IcciisMilic) |)\ riiiTiiduin ....... 088 ()2">. II(iri/(iiiliil scclicpii lliidiij^li j;1(i1mis jmllidus in iicwlKprii liahc . 085 ((2(>. Ilorizdiiliil .section iliroti;,^!! iiucitMis li'iitifiirmis in ncwhorn Imlic . 9H7 ((27. Horizontal scdion throuj,'!! nuclens lentifonnis in newborn Ijahc . 988 028. I[(iri/,onlal section tlinuij.;!! imclciis lentirorinis in newborn ])abe . t)89 029. Section at rigiil aiij:;le.s to liic longitudinal liiiri's ol" the basis pe- (Innculi (junction of upper with middle third); newborn babe, no to T)! cm. long 990 630. Transverse se('tit)n through the spinal cord of a newborn babe, about 50 cm. long ; level of sixth cervical nerve . . . 991 (Wl. Transverse section through the spinal cord of a newborn iiabe, about 50 cm. long; level of fourth lumbar nerve . . . 992 632. Early experiments of lieevorand llorsley at motor cerebral locali- zation 990 033, 634. Motor cerebral localization in the monkey . . . 998,999 035. Comparison of motor representation in the bonnet monkey and in the orang-outang 11)01 636. Sagittal section through the brain of the monkey, illustrating the internal capsule 1004 637. Position of fibres at various levels in the capsula interna of the nu)nkey 1005 638. Horizontal section through the right cerebral hemisphere cut at a distance of 01 mm. Vielow its superior border . . . 1006 639. Drawn from a photograph (nuignifled twice) of the outer surface of a monkey's left hemisphere 1009 040. Experimental stimulation of fresldy cut substantia alba of dog's s[>imil cord 1011 041. Degeneration following hu'morrhage of six months' duration in the nucleus lateralis thalami and in the lenticulo-optic por- tion of the (^apsula interna . 1013 642. Portion of pyramidal tract in cross section which has urulergone secondary degeneration ........ ll)15 643. Seeoiulary degeneration of motor fibres from the ])allitnn alter extensive cerebral lesion lOlH, 1019 644. Non-medullated fibres in the lemniscus at l)iith corresponding to the centrifugal bundles of the lemniscus .... 1031 645. Brain of monkey showing cortical area extirpated . . . 1024 646. Horizontal section of monkey's brain showing area of degenera- tion in internal capsule, following lesion of hallux centre . 1025 647. Degenerated area in Fig. 046, eidarged 1025 648. Decussatio pyramidum, hallux lesion, showing degeiu-rated fibres passing to fasciculus cerebro-spinalis lateralis of both sides . 1026 649. Spinal cord at the level of the eleventh thoracic root, hallux lesion. Bilateral degeneration 1027 650. Section of spiruil con! at the level of first cervical root; degen- eration in right fasciculus cerebro-spinalis lateralis after ex- cision of thximb centre of left hemis|)here .... 1028 1 ■' ' •':.i|i m% ■^ XXXll THE NKItVoUS SYSTEM. KimilK PAdB (i.-)!. Horizontal section of monkey's l)rain sliowiuff locution of degcn- enil ion I'oJlowing lesion oi' t lie fiieiiil ureii .... IO"J!» •).")2. Dcf^'eiieniled iireii in i-'i;,'. (Jo! enliir^etl lOtiO •"»iiu:li the ret^noii of the nucleus \. trochlearis and tluMlccussutio braciiii conjunctivi 1042 (!(!<). Scheme of the cominissiira anterior cerebri ..... 105G tiUT. .S(dicme of an antero-posterior section tlirouj,di the cerebrum showiii'^ the dis|)ositiou of the axonesof association neurones which connect the lobus frontalis with the lobus occi|)italis . 105!) U()8. W'rtical transverse section of the left occijiital lobe to show the orij;in aiul course of the slK)rt association tilires of the lobus occipitalis. .......... 1000 00!). Faci(.'S mcdialis lieiiiis|ilia'iii sinislri sliowiiij;;' the ciii^ulum, th fasciculus loiiifitudiiialis inferior, and other bundles of asso- ciation fibres .......... 1003 070. ^larchi preparation showini; deyeiieralion in doy's brain after destru(!t ion of the lobus frontalis lOOlJ 671. Lateral surface of the left cerebral hemispiiei'e .... 1004 672. X'crlical transverse sct^tion passinj,' throuf,di tiie posterior part of the pra>cuneiis. the fissura parieto-occipitalis. the (issura cal- carina. etc 1000 673. Two vertical transverse sections from a cerebral liemispliere. with aLTciicsis of the (!orpus callosum 1068 074. I'^isciculus occipito-froTitalis. taenia semicircularis. and fasciculus uiiciiiatus. 1009 075. View of lateral surface of ri.ii;lit cerebral hemispliere showing sense centres and as.sociat ion centres 1072 676. View of the medial surface of the left cerebral hemis])lier(> show- ing sense centres and association centres .... 1073 TiiK NKiJvors systi:m and its (X)\sTiTrh:xT N!orK()Ni^:s. siocrrioN r. THE HISTORY OF THE DEVELOPMENT OF THE NEURONE CONCEIT. ("II A ITER I. INTUODI'CTOIIY. 'I'iic stiiily of nciiroloji^y — (»liler views rcpinliiijj iku'vc mAU ami iicrvi; fibres — Dcitcrs' stiiilics — I'routisscs of iicrvt' (-t'lls — I'nitoiilasiiiic iiiid iixis- cyliiider proccssos — von (ierlach's studies — Idea of a ditliisi! iiervo network. In i'ucc of the iiuiiiy (lUi'stioiLS {loiiconiiiij,' htiotorial toxi- cology, intenml secretion, Holf-iiitoxicatioii, serotherupy, and organotherapy, subjects all fraught with jiractical import sufli- cicut to explain the abHorl)in()larity of the cells in the ganglia of the dorsal roots, and the origin of medulhited nerve fibres from them, although it was not until 187/) that Ranvier demonstrated the T-sliaped division of the process at a distance from the cell, while the real expla- nation of the unipolarity and its relation to the bipolar condi- tion in fishes was first worked out in the end)ryological studies of His. With regard to the connection of the nerve cells, within the central nervous system itself, with conduction juiths, the first observation is that of Wagner,t who in 1S47, while studying the electric lobe of the torpedo's brain, found that of the numerous jirocesses possessed by the nerve cells oidy one or rarely two remained unbraiudied and became connected with a nerve fibre, a finding whicli Remak in isr)4 asserted also for tlie cord and brain of the ox, and which in the following year he stated was true in general of all motor cells. The most important oltser- * Tlio (list'overy tliat the ventral roots of the spinal nerves are eoiicerned witii motion, tiie dorsal roots witli sensation, had lieen made earlier l)y tiie eminent British snrfjeon and anatomist. Sir (Uiarh's Hell. His views on the structure of tlie nervous system are eoiitained in the foliowinfj three works: (1) Idea of a New Amitomy of tlie Urain ; Sulimitteil for tii(> Ol)servations of his Friends, ;J6 pp. 8vo (liondon, IKll); (3) An P.xposition of the Natural System of the Nerves of tiie Human JJody, with a Uepuhlication of tiie Papers Delivered to the Hoyal Society on tlie Huliject of Nerves, vii, 3i)2 pp. Hvo (liOndon, 1824); (."$) The Nervous System of the Human Hody, etc., 4to (boiidon. 18;i0: third edition, Kdinlmrj^h, 1844). + Wafjner. R. Ueber der feineren lUui d(>s elektrischen Orpins ini Zitter- roclien, 4to(Gotlin};en. 1847) ; also, Neue I'ntersiiehungen iilier den Hau und die Fndigung der Nerven und die Struktur der Ganglien (Leipzig, 1817). I / 4 TIIK NKHVOrS SYS'l'KM. viitioiis 1111(1 j,'{Mu>niliz!iti())is of tliis period were, liowovtT, made by DcitjTH, tlio (listin^Mi'shcd invt'Hti^ator iit lioun, who, liko niiuiy others wlio hjivc siiccfSMt'iilly pursiUMl scientific studies, died iit 11 coMipiirutively curly a<,'c.* Deitcrs iimde an extroniely careful study of the various pro- cesses of nerve cells with the best te(!hnical methods at his dis- posal and classed them all in two ^jreat f,'roiips : ( 1 ) I'rotoplasriMc! processes which were branched and the internal structure of I'"l(i. I. — .Miillipdliir Kiiiittliciii cell fniiii tlic vciilriil Imni nf tlic <;rii,V niiittcr iif the spiicil ciinl iif llic ox. ( AlltT Dcili rs. i n, iixis-cyliiidcr pi-nccss ; h, |>ro- t(p|(l;tsliiir proiM'SSCS. which corresjionded closely to that of the body of the nerve cell, the i)rotoi)!asin of the process beinlyini,' to tlie foriner. lie tlioutflit tliJit the liner iixis-cylinder processes could be present in larjj:c numbers oil single nerve ceils, arising from the protoplasmic proensscs and going over into t lie fine medullated fibres of the central nervous organs. Tliese tlneraxis- cyliiuler processes liave becii recent ly proved iiy t lie delicate histological meth- ods of Held to be the terminals of axis-cylinder processes of other cells thus ending on, not, arising from, the cell with wliiidi they seem to be connected. DKVKLOI'MKNT OF TIIK NKI'lJoNK CONCKI'T. Waldcycr, in IiIh excellent review of the tiiorc recent inves- tipitions into the aniitoniy of tlie nervoiiM Hysteni,* lays eni- iiliasis upon tlie point tliat despite tliv enormous value of his researches Deiters did not actually demonstrate the connection of a <,'an},dion cell of the central nervous system with a periph- eral nerve lihre, a fact to whicdi Kolliker and (ierlaeh had pre- viously nuule reference. The eoiuuu-tions of the axis-cylinder processes of the cells of the ventral horns with the axis cylin- ders of the tihres of the motor roots of the spinal nerves were first ahsolutely cstahlished by the use of Weif^ert's mordant methods of staininj? the myelin sheath, f The countinfj experi- ments of Hir;(e J in Ludwij^^'s laboratory showed a remarkable accordance in the number of ventral horn cells and that of the lihres in the ventral roots, and led many physioloj^ists aiul anat- omists to the belief that each motor fibre in the ventral root is connected with a corresponding cell within the gray nuitter of the cord. More widely reaehitig in inllueiu-e, for some time at least, were the studies of (ierlaeh'* with the gold nietiiod ami the hypotheses which he based u))on them, hypotheses which were responsible for an immense amoutit of polemical writing during the fifteen years which followed their introduction, (ierlaeh, bv means of methods of isolation and treatnuMit with chloride of gold, obtained pictures surpassing by far, in extent and deli- cacy, any obtainable with the older methods, aiul affording an entirely new concept of the complexity of the structure of the * Waldeypr, \V. Uetipr ciiiijjp npuoro F'orsohunpon im Gobieto der Ana- tdtnic (los ('(Mitnilnervcnsystciiis. Deutsclie mod. Wdmschr., Iii'i|)Z., IHill, IW. xvii. S. 1244. 12(i7. 1287. l:Wl. lli.Vi. t Carl Woifijcrt's m.'thdds and tlic carmiii mothddsof (icrlacli in conjiuic- tion with improved t('('lini(|ii(' in sectioniiin; have contributpd enormously to llip advance of investigations in neurology. For the application of Wei- gert's methods to the nervous system of lower animals the experiments of C.J. Merrick maytic^ referred to with advantage. (Cf. Ilerrick. ("..I., {{eport upon a Series of Fxperimetits with the Weigert ^tethods — wiMi Special Hef- ereiice for Fse in Ijower Hrain Jforphology. The State Hospitals HuUetin, l^tica. vol. ii. 18!t7. pp. 4:51-461.) !(. Hirge, E. A. Die Zahl der Nervenfasern und der motorischen fiangli- enzellen iin Hi'ickenmark des Frosehes. Arch. f. Anat. u. F*hysiol.. Leipz., 1882. Physiol. Abth.. S. 4:{r)-48(). * V. (ierlaeh. .1. Article. The Spinal Cord, in A Manual of Histology by S. Strieker. American Translation. New York, 1872. mi -.ss^ 6 THE NERVOUS SYSTEM. gray matter of the spinal cord and Itrain. In addition to tho bodies of the nerve cells and their main processes, protoplasmic Fig. 3. — Network siipjioscd liy (Jcrliicli to Ix' foriiicil of the iinitopliisinic processes of the IK TVe cells. A ln'aiii liiliK iif'Ve tilire from tlie conl of tlie ox is shown whose two hniiiclies are connected witli a (ihre network which is lii rehiti fj;('iiosis of iicrvoii.s systoins. I'rinciph's of Psychology, New York. D. Applcton and ConipaTiy, vol. i. p. WO. 'V\w botanists, followinj? ospocially tho rcscurchos of (ianlincr, teat'h at present, thai in plant tissnes the protoplasm of all the cells forin.s a conHnunni, a fact which hinders many students of animal his- tolo<,'y from assertiiii; too jiositively the non-existence of such >i nmh'innnn in the tissues of adult animals. The demonstration comparatively recentlv of the so-called plasma bridges connecting ejiitlielial and endothelial cells, and also perhaps the elements of other ti.ssues with one another, is interest- ing in this connection. tin gold preparations it must have been extremely difllcull, and was probably impossible, to distinguish a network from a fcltwork. A German investigator, sju-aking of the frightfully intricate complex of fine ncrvo fibrils in the central nervous system, referred to it as the liirrji/z ih-r grauen Sulmtanz. — ml t 8 TIIK NKHVOUS SYSTEM. definite conduction paths or of localization of function within the central nervous system seemed well-nigh hopeless ; in the Fui. '.i. — SclH'iiif of ('(iiiiicctions of (Inrsjil and vt'iitnil roots of spinal cord accord- iiifj lo a discardi'd tlicory. (After Kanion y Cajal.) (/, (il)r(' of dorsal root supposed to liave its origin in Clarke's nucleus; /«. unipolar cells of spinal ftan^lioii ; il, lerniination of a dorsil root fibre in the reticulum of the dorsjil li )l*;i1 I'litliiim * 1' i\]iVi^ inirn ; c, root fibre K'uuf; to i)ass loufiitudinally in the lat<'riil coluiun ; /. fibre, from Clarke's nucleus ilirectcd toward the latenil colunni ; lasmic processes uuitiuK to form a lU'twork, (/, in which the fibres of the dorsal root terminate: c, cells of dorsal horns, the i)rotoiilasmic processes of which are united lo the lU'twork, (/ : s, ascending fasciculus of lateral col- umn : t. lateral pyramidal ti-.ict ; ii. r. fibres of dorsal root terininatint; in the network; .r. fasciculus cuiu'atus of Hurdacli ; //, fa.sciculus Knicilis of (ioll; i', median dorsal sulcus. genenil diffuse network investigators were halted by what ap- peared to be an insuperable btirrier. i;f 'M n) '■ I CHAPTER II. THE STUDIKS OF HIS, (iOLOI, AXl) FORKL. The nowcr iiivostigations— (iolgi's riictliod— Tyi)cs of nerve ecHs descrihed by(Ji)lgi— ("ell of Type 1 iind cell of Type II— Golgi's hy{)othcses— Con- tributions of His and Korel— ( tpposition to the idea of a nerve network — Orifjin of tlie idea of a nerve feltwork or neuropileni — Doctrine of the individuality of the nerve elements— The principle of contact for- mulated. Then followed a series of researches, the majority of which date since the year 1880, and with which the names of Ciolgi, His, P'orel, Kulliker, Ramon y Cajal, van (lehucliten, Retzius, and von Lenhossek are inseparably connected. These investi- ffiitions led to a complete revolution in the ideas regarding? the elements ot which the nervous system is constructed and the mode in which these elements are put together in its architec- ture. It may surprise many to learn that tlie now world-famed (iolgi's method was first described by its inventor, Camillo (lolgi, of Pavia, as early as 1873.* But little attention was paid to it by investigators in other countries, however, until more than twelve years later, when he published his volumi- nous article. Concerning the Finer Anatomy of the Central Organs of the Nervous System.f The method is now so well known that it is unnecessary to describe it here in detail. It will be recalled that it depends upon the treatment with a solu- tion of nitrate of silver after previous immersion of the per- fectly fresh tissue for a longer or shorter time in a solution of * Golgi. (". Sulla struttuni della sostanza gripia del cervello. Gazzetta niedica italiana lonibnnlia. t. vi, IHTIJ. (Jolgi's contributioT)s to the bibliog- raphy of the nervous system have been collected and translated inloCierman by Teuschcr. Cf. (Solgi. C, Untersuchungen ilber den feineren Bau des centrnlen imd {)oriphprischen Nervensystems, .lena, Fischer. 1S!)4. t Golgi, ('. Svilla fina anatomia degli organi centrali del sisteina ner- voao. Riv. sper. di freniatr., Heggio-Kniilia, 1882. vol. viii, pp. 165, 361 ; 1883, vol. ix, pp. 1, 161, 385; 1885, vol. xi, pp. 72, 193. 9 ill h I ifW 10 TIIM NKKVOUS SYSTKM. i! ■I •i-i bichromate of potiissiutn.* 'Vlw iiorvo cells and their processes stain ijitensely bla(^k and stand out prominently on the white or yellow j^round. Thi; pi(^tures obtained are in extent, clear- ness, and sliarpness, at least as far as tiie external form of the element is concenied, incomparably superior to those obtain- able by any other known technical method. f As a rule, cer- * The slow chroiiiate of silver metliod reeoniinoiuled by Ooljifi is used as follows: Pieces of tissue are hardened in Midler's fluid foi ai least one or two niontlis. They are then traiisfeiTed to a hath of dilute silver-nitrate solution, where they remain for from one to three days, after which the tis- sue may be out into sections, after very rapid imbetltliuf,'. The methoil n()W almost uiuversally employed is the (jnick method in which osniic acid and potassium bichromate arc used. Small pieces of liv- iiifj tissue, not exceeding four millimetres in thickn(!ss, are fixed, at a tem- perature of 'i'") ('., for from one to four days in the followinj^ mixture, rec'ommcnded by Ramon y Cajal: Bi(;hromate of potas.sium, !J {jrin. ; dis- tilled water, 100 c. c. ; one-per-cent solution of osnuc acid, 30 c. e. For each piece of tissue, four millimetres s(|uarc, ten cubi(^ centimetres of this mixture should be employed. After the fixation the pieces are (juickly washed in distilled water, and then immersed in a 0.75-per-eent solution of silver nitrate. They are permitted to remain in the silver bath for fi-om one to thi'ee days. They are then very rapidly imbediled in celloidin and cut into sections, .serial if desired, with the aid of a microtome. The sections are to be quickly dehydrated by passing them through sevei'al dishes of ninety- five-per-cent alcohol. The tdearing is iiest done with oil of bergamot (Berk- ley). On the slide the excess of oil is removed with blotting |)aper pressed directly upon the sections (Welch), and a drop of thi(^k balsam is plaix'd upon each section. No cover slip is to l)e applied. If desired, the sections may be mounted upon thin glass or isinglass, which may then be fastened to a glass slide by means of glass beads, the side on which the sections are being down, to protet^t them from dust (l"]dinger). For some researches the modification of Cox can be csj)ecially recom- mended. According to W. II. Cox (Tmpn'iguation des centralen Nervensys- tems mit (^uecksilbersalzen. Arch. f. mikr. Anat.. Hd. xxxvii (18!»1), S. 16), the fresh tissues arc to be hardened for from two to five months in the fol- lowing fluid: Of a five-per-ccnt solution of bichromate of potassium, 20 parts; five-per-eent solution of l)ichloride of mercury, 20 parts; distilled water, 40 parts. Mix, and add five-])er-cent solution of chromate of potas- sium, 10 parts. The tissues are then to be washed for half an hour in ninoty-per-cent alcohol, then imbedded and sectioned (preferably with the freezing microtome) as in (lolgi's method. The sec^tions are placed for from one to two hours in a five-pcr-cent solution of sodium carbonate, or in ammonia solution : then washed in distilled water, qidckly dehydrated, cleared, and mounted in balsam without cover glass. •f Such pictures alTord suitable objecsts for reproduction by photography. Compare the beautiful Atlas of Nerve Cells, of Starr, Strong, and fjcaming. DKVKLOPMENT OP TUK NKUROXE (^ONCKPT. 11 tiiin only of tlio nurve structures present are foutul to he iin- picgniited in a successful preparation. Whether this elt'ect is dependent or not upon functional conditions of the tissues at Fio. 4. — (lolfii's cell i)f Type I. (VU IVoiii tho optic tnict [ENT OF THE NEURONE CONCEPT. 13 of (iolgi in thu doiimin of neuro-liistolo difTerent varie- ties of malarial parasites transformed clinical ideas upon the subject and would alone have sufliced to make his imuu> lasting. "^ lilt '.'■■'' > ; t lii ■ . :»l I I It i h: I 14 THE NKllVOUS SYSTKM. arisinj; from tlio iniiistomosiH of protoplasmic processos and counuctc'd witli sensory fibres on the distal side of the net- Fir». 6. — (lol^i's cell of Typo TI or (icndnixcmo from the ('crchnitn of a cut. (AfU'r Ktillikcr. ) The coiirsc protophisinic j)ro(i'ss('s, x, iirc <'!isily distiiifjiiisliiilile from the uxis-cyliiidcr process, «. tlioiiKli the luttcT soon loses its identity, exhuiistiug itself l>y multiple divisiuii at a short distiince from the cell. '\ work, had no existence in fact, but that there did exist a diffuse nerv^ network (infreceio) within the gray matter * made up of * Golgi has never piotiirod tliis network, and in all his writings lie has spoken of it in a very indefinite manner and with great reserve. For exam- ple, in his Studi suUa fina anatomia degli organi centrali del sistema ner- itr DKVKLOl'MKNT OF TIIK NKUUONK COXCKPT. 15 the muny braiu'hos of the axis cylinders of the ci'lls of Type II jiiid the side fibrils of the axis cylinders of the cells of Type I. Protoplasmic! i)rocesses, in his opinion, possess no nervous I'luiction, but represent siin})ly portions of the j)r()toplasni of the nerve cell which run out to be connected with the blood- vessels or neuroglia cells in order to pither nourishment from them. (iol^'i believed that the dorsal root tibres on (•nterinjj^ the cord branch freely and terminate by becoming? a part of the diffuse nerve network in tiie gray matter, the sensory impulses reaching the axones of the motor fibres through their side fibrils, which, he thought, are connected witli the distal side of the general network. In this way the deiulrites and the cell body are excluded from the reflex arc (Fig. 7). Kpoch-niaking as were his actual discoveries, the admixture with facts of such liypothesea was indeed un- fortunate. The credit, I think with justice, has been given by both van (iehuchten and von Lcnhossek to His, of Leipsic, and to Forel, of Ziirich, for having directed the first telling blows against the doctrine of a ditfuse nerve network and in favor of the inde- pendence of the iiuiividual nerve elements. The distinguished anatomist* has since the year 1881 busied himself, in the main, with the study of the morphology and histogenesis of the nerve organs, and his results in this field may justly bt* classed among the most striking achievements of a life of indefatigable activity. vost), Miliino. 1H8G, \). iil, he says: "Out of all those branching's of the dif- ferent nerve processes there arises, of course, an extremely coni()li('ated texture which extends throughout the whole of the gray substance. That out of the innumerable further subdivisions by means of complicated anas- tomoscu there arises a network, in the strict sense, and not simply a felt- work, is very probable ; indeed, one would be inclined from some of my preparations to believe in it, but the extraordinary complication of the texture does not permit this to be declared as certain." In a later article, Ija rete nervosa diffusa degli orpani centrali del sistema nervoso; suo signi- fieato fisiologico (Rendiconti del U. Istituto Lombardo, ser. ii, vol. xxiv, 1891, pp. 595, 656 ; Traiisl. in Arch. ilal. de biol., Turin, 1891, t. xv, pp. 4;{4- 46;}), Golgi has dealt with this topic at length, replying to the objections which have been urged against the existence of the diffuse nerve network and commenting upon its physiological significance. * The monographs of His upon the chick and his researches upon the anatomy of human embryos contain results of personal work which repre- sent a goodly proportion of what is reliable in modern embryology. .' I l(i TIIK NKKVOUS SVSTKM. His iiivcslipitioiis 1(m1 him nirly to tho conclusion that from tho hofrinnin^' the forerunners of tiie nerve cells — the neuro- hliists — are entirely distinct from ansansen pictures distinctly, in Figs. Ill and 11:2 accompanying his re- port, the bifurcation of the libres of the dorsal roots of the spinal nerves. The criticism Avliich appeared at this ])eriod frou) the ])en of Forel, the celebrated Ziirich ])sychiatrist,]; is of extreme vahu! from a historical standpoint. Well versed in the results of pathological anatomy and experimental pathology, and ac- ((uainted with the earlier work of His, Forel, in a short essay, distuissed the status of nein'o-histology at the time, including in Ids criticism the results and hypotheses of (iolgi. He recog- ?uzed fully tlie importance of (Jolgi's objective fiiulings, but * At the 011(1 of fin iirticlo. Ziir rroscliiflitc dcs niPiisclilir'lipn Rilckcn- niiirkos, dated ISHfi, Ilis siiys : " Als festsleliciides I'riiicip vcrtrcte icli dahei (Icn Satz : dass jede Xervenfaser aiis eiiier cin/ijjeii Zclle als Aiisliiiifcr her- V()ru:('lit. TMese ist ilir jjenetisches. ilir nutritives und ilir fnnotioiielles Cen- truni: alle andoren N'erliindunjjen der I'^iser sind entweder nur niittelharo oder sie sind seciiiKliir entstanden." + Nansen. F. The Sirnctnn' and Coniljination f)f the ilistolojjieal FJc- ments in the Central Nervous System. Hcrgens Museum .\arst)er(>tninjj for 1HH(!. Tkrgeii, 1887. X Forel, A. Einige liirnanatoniisehe Hetraehtungen und Krtrehnisse. Areli. f. I'sychiat. und Xervenkr., Merl., lid. xviii. 1887, S. ltJ:2-l'J8. 8 i IS TIIK NKU vol's SVSTKM. h witli pt'ciiliiir kcomicss of iMTfcption sifted out the facts from (lie liypotlicscs. He I'litcrcd ii stroM<; protest upiiiist the net- work theory and spoke for the niaintenaiiee of tlie individual- ity of the nerve eh-jnents. Korel re(!o^'nized tlie iniporlance of the "caprice " of the (iolj^i method in sta'tiinj,' an cU'ImcmI only here and tliere as l)eariti;; u|miii the independence* of the nerve units, Itut it is his utilization (»f tiie studies of secondary de^'en- erations which makes liiH communication of the deepest si^niti- cance. Me j)()inted out that not only does the distal end of a divided motor lihre under<^'o rapid disintcfrnition after section (Uallerian de<,'eJieration), l)ut tiuit also, in contradiction to the d(»(!trinc of Waller, the proxinuil end underf^oes cellulipctal de- j^oneration, though often much more slowly (von (ludden's law), when the division of the lihre has occurred at the point of exit of the motor nerve from the central system. Korel further em- phasized the fact that when degeneration involves a tract of nerve fihres it extends only us fur as the termination of the tra(!t. If atrophy of nerve cells and nerve fihres occurs heyond the termination of the tract, it is of a fundamentally different character from that which aifects the tract under OTMKISS WITH (!()L(!l's Ml.TllOl) AND Wrni MODII'ICATIONS OK THAT M KTIIOD. lleseart'lit's of Ujiiiu'iii y ('ajal — Di'iiinl of occiirrt'iico of aiinsloniust's iiiiion^ norvc (>lciiu'iits — 'I'he collati^nil imuiclit's of tlio axis-cylinder processes — 'I'eiideiuty to external inurplioloyical iiiiiforinity aiiioiij;' the nerve elements — Transit ion forms i)elween cells of Type I and cells of I'ype II — The cells in sensory and motor rei,'ions — Studies of other investifjators. TliK cojitfibiit'oiis of Ford iind His, well sii])i)ort(>d and coiiviiiciiij,' as t'.cy were, did not, liowover, suilicc to (M"jidi(!ato tlio older ideas of a retieidiiin from minds in \vlii<'li tlicy were as firndy estahlislied as are most prejudices ntid ])re('on('eived ideas taken in with motiier's mili<. To ajjpreciate discoveries 1)ased partly iii)()n patholoe^ical experience, I)iit lartfely upon studies in Instojjenesis, a iield whose fruits had not yet at- tained the aiipreciation they (h'served, a conservative niedicial world re(piired, for its awakcninj,', inlliiences still more arous- inn the ailmiration atid respect of the whole scientiii(^ world ; he is a nu'dical / III 1110 rlrl. The story, oven if it be not true, is certaiidy well invented. Besjiu- ning with two articles in the year ISSS, oiu' ujxui the retina of 20 l)KVi:i,()l'MKNT OF TIIK NKl'lJONK CONCHl'T. LU liirds* 1111(1 Mic other upon the nerve fibres of the inoleeiilar liiyi'r of tlie eereliellimi,! K'jiiik'hi y Cajal exliihited diiriiij^ the next few years a most .istoiiisliiiii; iirodiietive activity, J wliieli, jiid<,Mii;j: from the nature of liis articles in current journals, is by no means yet exhausted. A brii'f in(|uiiy into tlie contributions of Ivanion y Cajal can not fail to make clear why tliey almost immediately attracti'd close attention in widi'ly distant <|uarti'rs. Leavinjjjout of con- sideration the immense mass of detailed discoveries with which Kaiiu'in y Cajal has enriched the liner atiatoniy of the spinal ; ord and brain, the salient features of his work, those which make i;; so si,i,Miilicaiit as re^^ards (»ur ])resent conce])t of the ele- mentary structure, arc (I) the demonstration (apparently defi- nite at the time) of the complete indejieiulenci' of at least the majority of the nerve elements, the branches of the axis cylin- ders formiiii; anastomoses lo more than those of the dendrites; ('■i) the appreciation of the widespread occurrence and signif- icances of the lateral branches (collaterals) of the axis-cylinder processes; and ()>) the demonstration of the striking uniformity ill ifcneral stru(!ture of the majority of the nerve elements in all parts despite multi])le minor morphological variations. (iolgi, as 1 have said, had denied the existence of a network made up of anastcmiosing protoplasmic ])rocossos, but helieved in a ditVuse nerve reticulum composed of the united fibrils re- sulting from the complicated subdivisions of the axis cylinders of cells of 'Vy\w II and the lateral fibrils of the axis cylinders of cells of Type I. The Spanish investigator emphatically denied * IJaiiion yCiiJal.S. Kstrnctiini ili' la iu'tiiuMlc lasAvcs. l{c\ ista 'rriiii. (Ic llisli)l(i^iu XdMiial, etc.. Nds. 1 y '2, Mayo y Apislo dc INHH, (^IikjIi'iI liy von Ij('Ii1i(>ss(''I<. •(■ Sdlirc las I'Mliras N'crvosias dc la ra])a Molecular del ('crcbclld. ivc- visla Trim, ilc Hist., etc., .Xj^oslo, ISSH. (^)uoli'(l iiy voii Ii('iilii>ss(''k. I 1 liavo rct'crt'iiccs Id no less than nine articles on tlic iicrvoiis systi'iii licariiif? liis iiMinc, pulilisiicd duriiif,' llic year IHilO alone. It would o('cu|iy too niucli space lo f,'ive here a coniplele list of his pulilicalioiis. ,\ii epilduie of his views is lo be found in Les iidiivelles idces sur la slruelure du sys- tenie nerveux clie/ I'lioninie el che/ les vertel)res. I"'rench by Azdulay, I'ai'is, I Hot. and in the Croonian Lecture, La line si ructure (les ccnl I'cs lu'rveux, I'roeeedinjjs of the iioyal Society, Ldndon, vol. Iv, lS!t4, pji. 4-f4-4(iH. 'i'his lecture was delivered in French and published in the same lanjiiuii^e. ,\ brief but naccurate ab-lracl of it ill Kuf^lish was prinled in I he IJritish Medical Journal, lHi)4, i, p. .")43. ■iH' m ^j^' 22 TIIK NKllVorS SYSTEM. M , i u i. ' the t'xistenco of iiiiy such ditfuriu mTvti network. lie main- tained that in tlus ccrobro-spiniil nervous system tlio axis-cylin- der processes and tiieir lat- eral hranclies, ])el()nii},'ilii(liiial saKJUiil scctidn of ilcii'sid l'iiiii. another cell seudinn an axis cylinder into the white matter; tliis imicess hifurcates, yiehlins an ascendiuj; and a de- sceiidini; tihre; A", another cell sendiii}; an axis cylinder down- ward in the dorsal fnnicnlus: /. /•'. and 'i', terminal arlinri/alioMs of axis-cylinder pmctsses ; />', termi- homs, mailV of them iimoug the nal arhiirizations in th<> firay mat- ,, » , i ' i i i » t<'r of collaterals from the white celis ot tlie ventnd hom. As sul..stance : a. .•ollatenil from one ^^ (^| tdtimatc fate of the US- ol the divisions ol a dorsal mot tihre; ft. collateral from the main cending and descending fibres trunk of a dorsil mot tihre heforc ... , ,, ». i ■ its Y-shaped division. resulting from tiie 1 -siiiiped * Uiirnon y C'ajal (Anut. Anz., 18i)f). Hd. v. p. 92) .says, " Dans Tepaisseur (le la n'lrion dii cordon de Goll." This should probaljly read "cordon de Burduch. i' m KEVELOPMENT OF THE NEURONE C'oNCEl'T. •_>:> division, "Runion y Ciijal rould not iit tlui time niiikc iiny dt'tinito statcincnl.* The great nund)ei's of niedullated ii])rps passing more or less ill Imndlos from the (U)rsal fasciculi into the gray substance had hcH'U generally re(M)gnized and could not indeed have very well been overlooked, so proiiiinent a part of the ])i('ture do they form in sections of the niedullated sjiinal (U)r(l stained by Weigert's method {vide Fig. 11). The observers thought them to be (1) niedullated axis cylinders passing from the cells of B Z . Klii. 11. — Cross sect idii of tlic cervical spinal cord ofa <'liil(l two years old. sliowiiiK tiiediillaled collaterals passing i" from t lie dorsal t'asciciili and ruimiii;; for- ward toward the ventral lionis. (After von KoUiker.l /, fasciculus fjiacilis (tiolli); /)', faseiciihis cuncatus ( Biirdaclii ) ; /., fasciculus of l-issaiier. till' gray matter into the wliite fasciculi, and {'i) fibres of the dorsal roots or of the dorsal white fasciculi turning in to ter- minate in the gniy matter. Uiimon y ("ajal proved that the * Through a eoinbinali' of the results attained l)y Golgi's methnd, by 1 he iiielhotls i)f secondary detrcneration and Fleehsig's einbryologieal method, we have now tolerably accurate ideas as to the course and destination of the lilires of the dorsal while fasciculi of the cord, their relations to the gray matter of the medulla spinalis and that of the medulla oblongata. Von Lenhossek has made an extremely careful study of the various groups of collaterals jiertaining to these fibres, and has given us in a monograiih (Der feinere Ban des Nervensystems im Lichte nenester Forschungen. zweile .\u(lage. Herlin, l.S!)5) a most interesting and reliable ri'siniK' of the facts at present known about the tiner anatomy of the cord, iiududing the results of his own brilliant researches upon the sjtinal cord of human beings. Kamon y Cajal's treatise (ii'anatomie fine de la moelle e|)iniere ; Liefernng iv of Mabes' Atlas der path. Histologic des Nervensystems, IJerlin, 18i)r)) may also be consulted in this connection. W 2<; THE NEltVOUS SYSTEM. I< i majority of these >lo not n'])r('S('nt iiiiiiii iixi« cylinders iit nil, l)iit are eollatenil hninciu'S, ii tiii(iiii umlorf^oiiig tlio V-slia[)i'il division; somi' infdiillal(>(l fibres [)ass from tlie gray matter l)ack\vard (centrifugal fihi'cs of dorsal roots in the lower vertehntti's, and fil)res of dorsal fasciculi whose cells of origin are sit ited within the gi'ay matter of the cord). f It was Ki'illiker who sliowed that the sensory cerebral nei'ves undergo V-shaped division in almost exactly the same niauiier as do the sensory sjiiual nerves. X tiolgi, iu his arti(!lo entitled Anatomical Considerations regarding tho Doctrine (jf Cerebral bocali/ation, in 1SS2 detailed the results of his studies on the cortex, from which he coucliule(l that the cells of Type I and 'I'yjio II were not separated from one another in the single convolutions, but wito always asso<'iated with one another in all parts of the corttix, and that ac- cordingly there were not only evidences against the strii^t separation > ■' tho two main functions, movement and sensation, l)ut also positive grounds for the assertion that in the dilferent cortiiNil zones there was no absolute sep- aration of the sensory and motor functions, and that the anatomical seats of these functions must to a certain degree bo intermingled. It is surprising DKVKhOPMKNT oK TIIK NKrilONE ("ONCKPT. •J 7 Ciijul's (lenioiistriitioiis the distinctioii.s hctwceii tlu'sct two tyj)c!S lost, ill the main, tiio sigiiiiiciiiu'c which had bi't'ii attacdiod to them. Tho only ossontial difference between cell Tyi)c I and cell 'IVpc IF was shown to lie in tho length ai\d mode of hranch- iiig of the axis cylinder. Whereas: that of the first type first l''l(' I ami llial of ( lolt;i's cell Typo II. (.VftiT von liCnlioss('k. ) Tlic iiiiit'li-braiu'licd axis-c.vlinilcr process « can 1«! followed into the fasciculus cinicatus of Hurdacli. /. r. showed an end arborization at a considerable distance from the cell, that of the second type broke np almost immediately after leaving its (^ell of origin into its terminal filaments. While a cell of Type I, through its long axis-cylinder ])rocess going diret^tly over into a nerve fibre, is put into position to affect other cells in widely distant domains,* the cells of Tyjie 11, the axis-cylinder processes of which rarely, if ever, Uuive the gray matter, are destined to influence other cells in the immediate iieighliorhood. These latter in all probability do not always act as servants of main conduction, but are to be looked upon how near — cvt^ii with false premises — an approacli to actual relations can bo Mrriv('(l at ! * Tho axis cylindors of sonic of the i)yrami(ial (^elLs of the I'crehral cortex attain a length of nearly one metro. ;:4 2S TIIK NKWVors SVSTKM. if .; as havinjj u di'tiiiite local funotioii, probably of no mean signifi- cance* Tlicv occur in motor as well as in sensory areas, and there is no j^roiind at all for attrihiitin\i\'u'i\ l)y von licnliossc'k, sciMiis to me most siiitaiiie as (list iiii^iiisli- in;; tlicm from cells of Type 1 or Iiia.roni'n. Seliiifer's name jini/i'ction cell lor the cell of 'I'ype I may easily lead to confusion, and T think is better avoided. Von Monakow (Arch. f. Psychiat. n. Nervenkr.. Hd. xx. 1H80, S. 7H1) seems to have been the first to rei^of^iii/.e the siirnilieance of Golgi's cells of Type II as SrhnUzellen. \ Von Hechterew. \V. Die fielire von den Xeiironen mid die Kntla- dungslheorie. Neurol, ("entralbl., Leipz., IM. xv, 18!)(», S. nO; 10;{. II DEVELOI'MENT OF THE XErilONE CONCEPT. 29 many, von Ki'illikcM',* von Ii('nlioss(''k, Waldovcr, and K(linache(l. Kxperimentin;^' alom; Ihtso lines, Khrlich found that hy injection iii/ni rifiuii of ii Holittion of methylene hi no dissolved in salt, solntion into the hlood-vessels of an animal, the axis cylinders of many of the nerve lihres (Ki^. 11) as well 1^ I i ^^^?*Z Fui. 14. — Nerve (ilires I'riim a (Vok injected willi metliylene liliie. (MetlKid of I'^lii'lieli. ) 'Pile axis eylinders iU'i' .stained diiik liine. In plaees tiie in,v<'liii slieall 1 IS soniewliat stained Me nixies (i r lianvier and the
  • lher the sulphur in the mole- cule exists as a pheiiylsiilpiiide oi- as a )/iienylsiilphoii. Finally, he made tests with IhiidsclieidltM-'s orveii i Diinrthj/lplicii i/h'iujriiii), which dilVers from methylene blue only in Iackiiia('tioii he thoufrht were (1) oxyji'en-.saturation ; (2) alkalinity. Whether or not he still holds to these ideas expre.s.sed in l.S,S('>, J am una hie t( ) Si ly- It was .soon (U'monstrated by Arnstein that iiijeiition infra vitam was unnecessary for tlie reaction, he having shown that as long as the tissues remained alive injection into the dead 4 S ( 1 ' t! 34 THE NERVOUS SYSTEM. aiiimul gave results etiually jjood. Mayer asserts that even several days after death the reaction is sometimes ohtainahle, and comhats the uk'H of a " vital " stainintj. Certain it is that sections of tissue cut with a Valentin's knife soon after removal from the hody and laid in a weak solution of the dye, stain beautifully. This fact I can assert from my own exiierience with human as well as with animal tissues. One serious objection to the methylene-blue method was the transiency of the staining. Attempts were made to overcome this, Pal using iodide of potassium, Smirnow iodine and iodid'ft of potassium, I)ogi( , an a(|ue()us solution of ammonium picrate, Mayer ami Hetzius ammonium ])icratc ami glycerin as a fixing agent, but no one of these methods was entirely satisfactory,* and the preparation of thin sections of the stained and imper- fectly fixed tissues remained an impossibility. Through the fortunate introduction of a fixing agent, which we owe to Bethe,f this difficulty has been almost entirely overcome, and * A very j^ood opilomo of tlie work (lone with the method up to 1891 is to be found in the eolleetive review by 11. Riese in tlie Centrulbi. f. ullg. Path. u. imlli. Aniit., .lena, Bd. ii (1891). S. 8:56-848. f Bethe. A. .Studien iil)er das Contraliiervensystem von Carriniin JI(fti(i-'i nebst Anguben iiber ein neues Verfiihren der Melhylenblaufixation. Airh. f. niikr. .\iiat., Monn. 1894-5, Bd. xliv. S. .579-622. The method depends upon eonverting the si ill Fi. — l.vW lialf (if liniiii ^'iuiKlinn of S,-iri.i dnryslcolnf witli tlic ncrvt's couiic'ti'd witli it si'cii fnm; tlic tlnrsil siirfiUT. MctliylciU'-liliic staiiiiiiff, lixation by Hitlic's inctlKid. ( After (i. Kctziiis, ISlHi. taken I'liiiii I{aiil)er's Aniitdmii' (ks Mruxrliiii. 5. Aiill., 15(1. ii. S. S5ti. ) <;, anterior f,M";>''>"P "f Kanjtlioii cells; sii, ))ipiilar cells of sensory type, the periiilienil processes of which k<> t«) a spot in the skin (.•<), to end there: jir. anterior aKKi'eKation of coarse Knmnles; iiii. anteniia-ni'rve tilires ; ((.antenna; m. denilritically liranclietl nerve lihre (niuscnli rve ) ; h, nerve liranches. liraiicliinK of coaisely fininular lilires ; pii. nerves to pal|> ; <■, coimnissural hranches of nenr.il cord fjoinn to siilHcsophaKeal xanjjlion ; iiii, pij^ineiited eyes. i!li 36 TiiK NKRvors svstp:m. Ii n > it is now possilHc not only to fix heautifnlly tlio structures at tlie height of the staining, V\^. lO, hut also to inihed the tis- sues thus fixed in puniftin, whicli permits of the preparation of sections of any desired tliiuuess and so to counter-staining by means of suitable dyes, for example, alum-cochineal.* I have laid some stress upon the introduction of the methy- lene-blue method, but not more, perha])s, than its im])ortan(^e warrants. As von Lenhossek has said, until the introduction of the (iolgi stain, no one probably had seen a lu'rve cell with all its processes — a complete lu'rve uiut in its totality. But even with the (iolgi stain not every element impregmited can be followed throughout its whole extent. Iiuleed, it is ])erhaps the rule tiiat where the medullary sheath begins the silver impregmition of the axis-cylinder ju'ocess ceases. The stain- ing of lu'rvi' eiulings in adult structures with the (iolgi method, even with double and tri])le impregnations, succeeds only rarely. Hut just here lies the great value of Khrlich's method. With a little care and a good sample of inethyh-ne blue the nerve eiulings and the axis cylinders of nu'didlated fibres, with which they are continuous, can l)e stained in a way far surpassing in constancy and completeness tlie best results of the uncertain gold chloride ]irocedure. Already most iiii- l)ortaiit contributions have been made with this method I)y Ehrlich, Dogiel, Retzius, Si.iiruow, Rauinu y Cajal, von Len- hossek, Symonowicz, Iluber, Bethe, aiul others, and it may safely l)e predicted that with the recent improvements it will be much more widely and successfully ap[)lied. That the method is also applicable to the study of pathological tissues removi'd by operation from hiinian beings has been shown by *Wilh liiivilowsky's modinciitioii of I'^lirlicli's iiu'tliod. t(>,i,a'tlii'r with |{ftlH'"s fixing pniciMlmv. I lia\(> Ixrii iil)li' to (Iciiioiisti-iilc iicrvc ('iiiliii;,'s in liuiiian 1111(1 animal tissues in a inaniu'i- ciuiri'lv siiiicrsciliiiiif any otlior mctliod known to inc. Tlii' comparison of tiic uradnal aiipcarancc of structure after structure ami of detail after detail in the tissue durinj? tlio stainiiiix to tlie development of a pliotojjraphic lU'Siitive. an illustration emiiloyeil i)y Lavdowsky, is very apt. If the stain l)e pushe(l too far the picture l)ec()nu\s clouded, owinj; to difTuse staininij of the other tissues with tlip l)lne — it lias been "overdeveloped." The methods of vital injection of methylene lilue used at Wood's lloll. Mass., hav(> htMMi descrilie(l hy Morill, A. 1)., .\iner. Naturalist, vol. xxx. ISIHI, |)p. ,s,")7-S.")!). Ilulier has de.scrilied the methods he employs in the Journal of Afipliod Micro.scopy, Rochester, vol. i, IS'JM, pp. (i4^(57. Ill DEVELOPiMENT OP THE NEURONE C'ONCEl'T. 37 the resejirches of Yonnj?, in wliich by nioiins of it ho has hoen iihlo to (k'nioiistnitc the jn'i'soiicc of m-rvos in certain tumors.* The results liitherto attained with Khrlich's inetliods have coniirined and ehi])orated tiu)se of the (iol^i methods, except, perhai)s, in one particuhir. Some observers, notably Dojfiel, the distintfuished Russian histolo<:jist, have inaintaiiu'd that in the metiiylene-blue specimens an aiuistoinosis of the proto- plasmic processes of one and of neighborinjjf nerve cells can be demonstrated. Indeed, if his illustrations represent the actual conditions, it becomes necessary to somewhat modify the ideas re('riiniMilal Medi- cine, N. Y., IS!)?, vol. ii. No. {. I.]). 1-12. t Masius. Jean. Reclicrciies iiistologicjues sur le systunie ncrveux cen- tral. Arch, de biol., (iand, tome xii. 1M!(2. pp. l.Tl-Ki?. 88 THE NERVOUS SYSTEM. F t i doubtod ; for not only liuve thoy been seen ])y investigiitors working witli tlie methylene-bkie method, l)ut Tartuferi and others have found them in tissues inii)rognated by the chrome- silver procedure. The work of Behi Haller, (iocppert, and Edinger speaks also for the occurrence now and tlien of aiuis- tomoses even of a coarser sort between the processes of neigh- boring units. The much-used simile, however, that the i)ro- cesses (and their divisions) of nerve cells maintain, in the vast majority of instances, tlieir identity throughout, interlacing perhaps with one another or with similar processes from other nerve cells, just as the branches of the trees iii a dense forest may intermingle but remain indcpetident of one another, the nerve elements being as separate and as inde];endent as the trees and their branches aiul leaves, has iipi)art.iily, (if h'ltsf so far (IS fin/ji'i/iniic f issues arc coHccrncd^ had its complete ana- tomical justification. Hhould occasional anastomoses between the processes of nerve cells be even proved to occur, or should it be true, as seems likely from the Avork of Held, Apathy, and Bethe {vide infra)., that in adult life reciprocal relations exist of a far more intimate sort tiian those that obtain in the em- bryo, the general validity of the doctrine of the individuality of the neurones would not be affected. u f. ¥ 'i!i CHAPTER V. WW THE TRUM "XEUROXE" AXI) THE NEUROXR COXCEPTION. Waldeyer's review, in 1891, of the newer iuvostif,'ations — The term noirmii' applied to the whole nerve unit — The neurone conception of the nerv. ous system. In' ISni Wtildeyer did great service to the new doctrine by bringing together within a brief compass and in a clear and convincing manner the results up to that time attained, com- paring the experiments of the different investigators with one another and submitting all to his keen and critical judgment. His article * perliaps has done more than any other single publication to make generally popular the doctrine of the in- dividuality of the nerve elements for other reasons, but more especially from the fact that — and this is a point upon wliich von Lenhossek lays emphasis — besides his i lear presentation of the established discoveries lie introduced a term for the histological unit in the nervous system (including the whole element — cell body, protoplasmic processes, axis-cylinder pro- cesses, end arborization, and collaterals), dubbing it euphoni- ously in (ierman Xciirnn (Greek, o vevpoW; English, iwnrone), a term which has been almost universally adopted by amitoinists, physiologists, pathologists, and clinicians in various countries. Objections to the use of the word neurone as a designation for the nerve unit have been offered by KoUiker, Schiifer, and others. It is, however, so much more convenient a term than any other which has so far been suggested, and, moreover, has already entered so thoroughly into common usage, jiermeating the bibliography of all specialties, that I think it must be accepted ; if so, the use of the term " neuron " as a name for the axis-cylinder process, as advocated by Schiifer in his admi- rable essay The Xerve Cell Considered as the Basis of Neu- rology,! is to be deprecated, and more particularly because a * Waldeyer, W. Op. cit. f Schiifer, E. A. Brain, Loiul., vol. xvi, 1893, pp. 134-169. 39 40 THE NEIIVOUS SYSTEM. r I I il i tow tlistiiifjuishod toacliers huve been induced to continue the use of tlie term in this wuy, thus leiidinyed by Schiifer to meiin tlie axis cylinder (axone or neurite) and by Wilder to indicate the central nervous axis, and since the ori- gin of the one term is the (Jreek vtvpov and the orifj^in of tliat suggested l)y Waldeyer is the (Ireek vcvpwr, the (lesiral)ility of spelling the latter in Knglisii " neurone," and of pronouncing it neurone, is all tlie more obvious.* In the accompanying illustration (Fig. 17) a typical example of a lower motor neu- rone is shown in diagram. The cell body with all its pro- cesses, including that extcjiding to the mugcle fibres, makes up the total mass of one neuroiu'. Enough has been said, 1 hope, to make clear what is meant by the " neurone concept " of the nervous system. To sum it up in a few words : The nervous system, aside from its neu- roglia, ependymul cells, blood-vessels, and lymphatics, consists of an eiu)rm()us number of individual elements or neurones. Each neurone in its entirety represents a single body cell. These units are at first eiifireli/ (if protoplasmic bridge^" be excepted) and continue throughout life relalii'i'ly to be mor- * Kollikor (lliui(ll)uch di-r ({ewcbelohre dcs Mciisclien. 1893, Bd. ii, S. 2) states his ohjcctioii as follows: "Das Wort Xeiirnn^Ni'iiroiteii. das j^iit kliiiyt, kaiiii spnioliiich niclit f;;obrauclit werdoii, wie voi'fjcsclilagoii wurde, denn cs bedeutet eincii Saiiiinel|>unkt vieler Xeiiren oder Nerven. Von den Worteii Neiirodoiiib'cii uiid NiMirodciKb-idicii ist das letztere. obschon liiii^'cr. als rt'bersetzung von Nervenbiiiiinclifii docli viclluiclit oiitsprccluMidur." The adoption, however, of the better sounding word is in this instance easily intelligible, and, moreover, is not without many a jireeedent, as the phi- lologist must sorrowfully gi-ant. In the present case, however. Professor B. L. Gildersleeve, of the Johns Hopkins University, informs me that Kolliker's objection to vtvpiau will not hold, as it would apjily e.(|ually well to irapQfviiiv. which means "Ihe house of the vii-gin." Wliile the s])i'lling neurone is not pleasing, for tiiat matter neither are the spellings anode and rat/tude, which, after the analogy of mef/iod, should be spelled anod and caf/iod, but, under the circumstances, in order to anglicize Waldeyer's term, tlie use of the word and spelling neurone seems, as Professor (Jilder- sleeve says, to be inevitable. (\f. Barker, \i. V. Concerning Neurological Nomenclature. .Johns Hopkins Hospital Bidlelin, Bait.. 1S9(), vol. vii. I>. 200. Frank Baker, of Washington (New York ;\Iedical .lournal. vol. Ixiii (1800). p. ;5T;{: and in I'roe. Ass. Am. Anat., 18!l.'). Wasli., 18!J(). vol. viii, pp. 40-45), has suggested the term nenre, corres|)onding to IJauber's neura, for the nerve unit, a nomenclature which has received the support of C. S. Minot. DEVELOPMEXT OF THE NEURONE CONCEl'T. 41 FKi. 17. — Sclicmc 111' liiwcr iiiotdr iicuroiu'. Tlic iiKitor cell l)ii(ly. tciK<'tlii'r witli mII its |inptcp|ilasiiiic pnM'csscs, its a.\is-cyliii 44 TIIK NKHVOUS SYSTKM. !| witliiii till' limits of tlmt iniit or Hct of units, any (Ic^ciioriition of other units hcin*; of an entirely ditferent nature, atul when reseinhiin;^ the former oeeiirrin;,' much more slowly ; and (4) tlio liist()lo<;i('al (lemonstriitiou of the fa(;t that, for reiisouH as yet too s\il)tle for aiuilysis, sometimes one unit, sonietinu's an- other, may he picked out hy a particidar method of staininj,' or imprejfiiatioii and l)rou^dit excjuisitely into view, others near hy renuiinini,' only j)artially staiiu'd or entirely unaffected. In ad- dition, the doctrine ajjrees well with all the known facts discov- ered by Kdin;i;er, Ilerrick, and others in the field of compara- tive anatomy. Have these data been proved to be unreliable?' With regard to the cell doctrine it may be said to be now universally held, although it is true tlmt it does not explain all known fa<'ts, and that here and there a distinguished biologist draws attention to its " ina(le(|uacy." * Thi' end)ryol()gical researches of llis con- ceriung the lu'uroblasts have been manifoldly contirmed by his own and by other methods. Not until we c(mie to the studies of degeneration inside the nervous system do we find any ajipear- ance of discre])ancy. The docstrines of von (Judden and von Monakow, on the whole, however, still hohl. Lesion of a given set of neurones causes degeneration of the tyjjical and gener- ally recognized sort (that revealed by Weigert's method) only within the domains of that set. If large numbers of lu'urones belonging to a given system degeiu'rate and are absorbed, there may be, it is true, after the la})si' of a very long time, jmssibly total atrophy with absorption in neurones of another order (as pro])ably occurred in the case reported by Flechsig and Iloesel, in which the corticopetal lU'urones of the general sensory path had been injured by a lesion involving the central gyri, aiul after many years many of the Jieuroiu's, the axotu's of which go to nuike uj) the internal arcuate fibres of the medulla oblon- gata and the fibres of the lemniscus medialis, had entirely disap- jH'ared). But, as a rule, the tertiary change is one of shrinking and dimiiiution of the calibre of the medullated fibres rather f ' f I * Cf. Whifmaii. ('. <». Tlio limdcqimcy of tlic Cell Theory of Devi'lojy- mcnt. Wood's IIoll Hioloiiiciil liccliircs, 18!):! ; also in .1. Mor|)liol.. Host., vol. viii. 18!)!!, pp. (i:!!)-(i.')S ; aiul Scd^rwick, A., On tiic liiadtMjiiacy of tlic Cellular Theory of Development, and on the Early Development of Nerves, particMdarly of tlie Third Xerve and of the Sympathetic in l^lasmobranchii. (^uart. .1. Mier. Sc, ivonil., vol. xxxvii, 1H!)4-T), pp. 8T-101, li It DKVKIiOI'MKNT OF TIIK NKUKONK CONCKI'T, 45 tliaii ('((iiiplctc (liHiiitc^rriition and absorption (as tlic condition in wliicii the liracliiuni conjnnctivnin is ordinarily found after extt'nsivi' diseaso of one cerebral heniisplicrc fully illustrates). Siiu'o 18!(1 a vast deal of work Jipon dejfenerations has heeii done with two methods which are especially well adapted for yieldiiifi: information, especially in tissues obtained too soon after the lesion to be of value for study by the method of Wei- gert.* 'V\w tirst of these methods, that of Marchi, thus far speakrt strojiirly in Its results for the validity of the neurone doctritie. 'IMiere is no evidence from its use that a dejjjenera- tion followinj,' an injury I'xtends beyoml the limits of the lU'U- rone or neurones whi(di the lesion involves. On the contrary, the method is mainly of value since it permits the following of a set of diseased fibres to their termination. Hy its aitl the ex- act course and distribution of (iowers' tract as far as its ending in the cerebellar worm havc^ been followe»issl,an(l its various moditicalions have been extraordinarily active. The procedure is an extremely delicate one, and changes hitherto entirely unsuspected have been detected by it in various ])athological conditions. Through it, in one respect at least, the neurone conception has l)een supi)orted, for the method has demonstrated that, when any portion of an axone or its terminal raiuitications is diseased, tlu* whole lu'urone to which that axone l)elongs suffers, the (dianges which oc(nir in the "stainable substaiure " or " tigroid " of the cell Ixtdy and dendrites of a neurone after lesion to its axone being now gener- ally recognized aniit eli.-iiiters. f Persoiijii ('omiiiiinication. X Wiirrinfj^ton, \V. U. (>ii the Slriictiiral AltiTiitions oliserveil in Xervo Cells. J. Physiol., Ijond. and Caml)r., 18i)8, vol. viii, Nos. I and 3. % : I, ;1;M ,<» m i«! IP i M^ TIIK NKUVors SVSTHM. r i i 1' ten tlmt ill ccrtniii iiistiuiccH the (tutting thr()ii<;li of ii ccrcbriil Hfiisory lUTVi' between its <;aii;,'li(»u mid the ceiitnil nervoii.s wyH- ti-rii (or, •:; terms of the neurone conception, sohition of con- tinuity of tlie iixoiies of sensory neurones of tiie first order) is followed by chungeH in the nucleus terininalis of the iiervt* (|uite like those which occur in the cells of the peripheral ^'iin- <,'lion itself after section of the sensory nerve Detween the f,'an- fj[lion and the periphery of tlie iiody, or like those which follow in a ni(»tor nucleus uiion section of the root fibres issuiii^^ from it. llij^hly interestinj; as the phenomenon is, and as yet insutH- cieiitly explainecl, it can hardly be said t(t iii any way invalidate the neurone conception. The fact that an injury to one indi- vidual in a socit'ty U-ads to tin- detriment of certain otlier indi- viduals with whom the former individual was most intimately associated, can not be considered as disproving the idea that the .society is comiiosed of individuals. And that, in the ease of the neurones under consideration, the character of the in- jury in the periiihcral and in the central neurone ditfer is obvi- ous from the subseciuent history of the two neurones in ani- mals permitted to live for some time after the injury. In the one instance typical Wallerian de^'encration with absorption (piickly takes jilaee, in the other there is at most slow secondary atrophy. Histolofiically, there have been since 18!) 1 repeated confir- mations of the earlier siufjle observations of coarse anastomoses of dendrites. In niamiiials the findine- cially well siiiti'd for the study (e. ij., tlie nucleus of the trape- zoid hody), that when the ter- minal of an axone comes into contact relation with the cell hody of another neurone one can always make out where the l)rotoi)lasm of the one neurone ends and where that of tlie secv ond he.) FixMtidii with van (icliiielilcii'.s iiii\liiic ; slaiiiiiif; willi inm-ha'iiia- tiiN.vliii. 'I'lic laijjf a.Miiif is seen Icriiiiiiatiii;; ii|i(in tlic cell and <'\- liiliiliuK what Meld calls ccincics- cciicc relation. The small aMiiie with itsaxinie hillnct; isarisint; iVoin the cell hody shown in the liKlire. A ■I -i.f. Fl(i. lil.— Cells IVoin the I'lc. us coi-|ioiis tiai)ezoidei of thi- iidult lahhil. ( Alter II. Held, .\ich. f. Anat. n. rii.vsiol.. .\nat. Ahth., Leipz.. |S!(7, II. :{ n. I. 'I'al'. xii, V'\%. t. ) .\lcohol (ixation : slaininLj with iidn-ha'niatox.^lin ; ditleiciit t'oiiiisol' intracellular lilires y'l.f.) are shown. The lilire I'liteiiu^; th. cell in the lower rinht-hand corner of the linnre is, accord : to llild, ccrtainl.v an axis cylinder. .V, nucleus. I • m DEVKIiOPMKNT OF TUK NKniONK TONOKPT. 49 ! ; nil 50 THE NKHVOCrS SYSTEM. nals of one lu'iironc pluiijje deep into tlic coll body of another neurone and even come into close proximity to tlie nucleus of the hitter (Fi:;. 1!)). He describes the relation as one of "concrescence." lleld's pictures are very convincin.^;^^'-^ Ih iiiliites of mitral cells. Fl(i. 21. —(iliiiiicnilusoiriictiprins from adult nililiif. ( After II. IIcM. .\w\\. f. .\iiiit. 11. I'liysiip].. .\n;il. .\litli.. Lcip/... IsilT. 'I'lif. ix. Fi^'. l:?. ) ( 'lirciiiic-ipsniic ti.xa- tiiiii iiiiil staiiiiiif; liy .Mtmanii": inctlinil willi acid fiudisiii : sli^lit ditl'iriiitia- tioii. .\ disliiicl ditrfrciicc can 1)1 made out hctwccii the uuiulicr of uciiro- soiiifs ill the hcKiiiiiiiifisof llic dendrites of I lie luilral cells and llie term i nals of the iiervi olfactorii. The niiildle part of the >;lonierulus lias not been drawn. seems to Inive discovered a method of staining certain minute jtarticles (his neurosomes) in the ground substance of the pro- toplasm of the neurones — a method whicli stains thcni intensely DEVKIiOPMENT OF TIIK NKL'RON'K CONCKI'T. 51 ;iii(l k-avt's the other structures but dimly i»r not iit all tinged. It would seem that, according to his report, the neurosomes are ('(i/iiiiiii/ ■•• .. • • :^"4 ■'.'•■ X 'k- ■■ ■ ■■*■■ ■• .••*■ ♦■•.; t'.^ .'o^ > ';\\\,^P .Yc/Tc ((7/ ii/ tliv iiuiliiiiliir siiiif rniir.ifi ilfiiilriten nf Purkinji' I'lllf Fkj. 'Z'l. — A iMii'liiiii ipf tlic iiKilcciiliir /.(Pile (if llic <'<'n'l)cllimi nf an luliill nililiit. (After II. Ilclil. Arch. f. Anal. ii. Pliysinl., \\\;\\. Al)tli.. I.ciiiz.. Isil7. Siipjil. 15(1.. Taf. .\iii. Fij;. 1.) I'ai'allin section 1..") inicrcms tliick. I'.rytlinisin- nictliyifnc-liliic. Tlic |pcriil('i..lritic lirancliis of lianion y Cajal's cliniliinj; tilu'cs liKik like •;rannlar l)iinils ipwin^ tii tlif procncf in tlum ;)!' laifjc nimi- licrs (if nciinpsdnus. I , .'1 ■ i.i 4i ' ■; < x-y far more closely aggregated in tlie tixis cylinder, and especially in it.-! terminal l)ranches, than they are in the ])roto])l;ism of the cell bctdy or of the dendrites of ti neurone. Thus, in the olfiuv tory glomeruli (Fig. 'l\) it is very easy to distinguish the axoues of the ncrvi olfactorii from the dendrites of the mitral cells and of the brush cells, both of whicli, as is well known, entt'r into the forniiilion of these curious bodies. Agitin, in the molecular liiyer of the cerebelliir corte.x, lleld's netu'osoine nu'thod out- lines accurately the ])osition ami relations of the terminals of the ;ix(»nes which climb trellislike along the trunks of the huge limbs of the cerebelliir forest whi(d» is made up of the dendrites of the I'urkinje cells (Fig. "i'l). Ileld's contributions, there- fore, tar from disproving it, are contirnuitory of the neuroma doctriiu'; ami, its a mtitter of fact. Held represents one of the ablest of the (ierniitn iidherents of the doctrine. iilHi* 52 THE NERVOUS SYSTEM. H i Advortiiijj; HiiiiUy to tlio inv(>sti:illi.v. Mittli. aiisdcrzonl. St. zii Nca- pcl. I'ld. xii. IsilT. II. t. Tal'. .\.\vii. Fij;. 7. i .\ primitive liliril, s/ifi';]. i:s .seen (111 its way III a yanj;liiin eell heimnin;; tliiiiiu r. (iwinj; to tlie einissinn of the side tihrils. A very cuniplicaleil iiitraeellidar relieiiiiini nl' neiiru-lilirils is to lie made out in tile format ion III' wliicli the piiniitive lilirils of all tlie pmeesses lake part. /.■/.■. nuclenliis : /,■. nucleus, a and ^ are processes conlainin;j one primilive liliril in each, whicli arriving in Ihe cell hody split np into seveial liifiirialin;; nenro-liluils. The |iriniilive Jihril in a can he followed for a ver.y hint; distance, heinii thicker at a distance fiom the cell. The coarse lon-jitu- dinal piiieesses y and iS contain a larj;e nnndier of primitive lilirils whi( li, as far as they can he I'ollowed, do not unite to one liliril. DEVELOPxMENT OF THE NEUKONE CONCEPT. 55 ' '^ pin Fio. 25. — Tlic ])lcxus (tf nc'iiro-tibrils in sonic retinal colls, II, h. <: it. (if the lliinl n^lit cyi' ol'tlic Iccfli, ( After S. Apiitliy. Mittli. iiiis (ler zudi. St. zii Neaixl. Hd. xii. isit", II. t. 'i'al'. xxviii, Kif;. V2. ) Tlie relation ol ilie inieleus, A', to the i)lexiis of neuro-filirils is well shown. "Con- '' ducting " anastomoses visilile helween the eell c and (/. ;»/, " eondnctinK " jirimitive lihril ; (oi, "eondnetinK " anastomoses: r/;«. radially striiK'd zon(( of the vitreons of the retinal et Us ; Irjn. (dear zone of the vitreons of the ret- inal cidls; iilij. pigment; rli, projeetinn hillock of somatoidasm. ;//,/) <7i/.7i" ^. rz kzo . ^— ___^ . /|2() IIZO '■ . ar ic FUJ. 20.— A snhepidennal sense cell, retiu.il et II from pseudo-hnuK hellion. (After S. Apiithv. Milth.ansderzocd.St. zn Neapel. Hd. xii. 1S!I7. M I, Taf. xxxi. Fij;. !>. ) II. vitreons ; h. ctdl nnidens : c. cell hody ; ir. the limiting line of the diame- ter of the vitreons; m: the outer contour line of the periidiery id' the somato- plasni immediately adjacent to the vitreons: ijni. prohalily thin ^.'lia memhrane whi(di accompanies tin' "conductinK " luimilive tiliril. Ipf. oiit>ide the in riti- hrillar mantle as far as the cell. The peri lilnillar mantle is lost at the cell sur- face : c/i/,/,-. (diromatic nm leolus ; ;//.•;>. vitreon> of the retinal cell : (/:«. radially striped zoneof tln' vitreons: h.u. idearzone of the vitreons : /7,;), internal hody \ hiiiciikorr)er) of the vitreous: A-.'/. j;rannlar zone of the vitreous. I »1 H 56 TIIK NKH vol's SVSTKM. cell l)(i(ly projM'r by tlic so-cjiUcd outer alvcoliir zone. Tlio periphery of tli(^ cell jn'ttpcr consists of iiii outer cliroJUiitie zone, iiisido wliicli is an "■ inner Jilveolar zone." Inside this Fui. 27. — The (listrilmtidii of (lie iiciir«i-lil)rils in (lie ciriiiliir iiiiisclc lihrc of tlic iiili'stiii;il wall of i)ciiitiili(lclla. ( AI'Iit S. Apiilliy, Mitlli. mis der zool. SI. y.n Ncapcl. iiil. xii, IsitT. II. t, 'I'aC. \.\xii, Fiy, ;i, ) Only a iclalivcly .slioil piece of llie lent;. Iiand-sliapeil llalleiieil-onl niuscle Mine is repi'es<'nle(l. The Inaneli- iuH 111' the enleiin^' IK iiici-fihiil can !»■ t'lilloweil lliniiit;li the whole Ihiekness oC the (ilire. /(/', " conclliclin^ " primitive lihril ; hi, ninscle lihre ; », place where "conilnctiiiK " piiniilivc lihril tnrns anf the cells and to the arranj^ement of the neund reticulum inside, Apathy distinF TIIK XKIKONK CONCKl'T. 1 iM iH" I'f Vui. 'J8. — (^^olossiil ^iiiiKlioii c(ll (TyiH! ;;) IVmii tlic Icccli. (AI'Ut S. Apatliy, MiUli. aiis (Icr /.(Hil. St. zu Nfiipc'l, Hi'l. xii. \m~, II. I, Tal'. x.wiii, FIks. 4, 5, iliid rtlic KiiiiKlioii ceil ; Ijif, " I'oiidiiclinjj " priiiiitlvf filiril. (!J) Cross scctiun. k. miclciis. (;{) 'I'lic iiicridiaiiliki^ dcciissiition (if the iii'urd- librils at tlio poli; of the cell is illustiiit^ul. 68. TIIK NKUVOl'S SYSTKM. ill' ■1 V! side of tlio cell most distiiiit from the stem profcsa tlio nciiro- lil)rils turn ahout iiiid iij,'iiiii j)luii<,'t' tliroii;,'!) tlic (u'll, coiivit^mii;,' to puss out of it l)y wiiy of tho pyriform process, whicdi is thus seen to curry two sots of m'uro-tll)rilla', which Apathy hcliows serve ill the one cusc for cellulipetul und in the other for cel- lidifu;,^! conduction (Vijr. "-iS). In the small type of rils which ramify inside the muscle cell. Hut altiiou ^^ f/. 1.0 I.I bi£i2.8 ■ 30 "^^ IM 2.2 II-25 11.4 2.0 1.6 <-V# ^-y Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4503 .V k«»' ■^ O V^volutionary and out of accord witl. the great principles wiiich com- petent neurologists believe to be incontroverlibly estaldishedf I ^ i' ^■ 1)KVKL()I»MENT OF TIIK XKrRONK CONCKPT. 03 ncrvoU'! system, at least for many of the cells of the hotly, is taufflit and demonstrated in every histolotjical lahoratory, and the lihrils in the pnxH'sses and the reticula in the eell hody have l)een the o])jeet of study and the topic of discnssion, too often of hitter polemic, for at k'ast two generations. 'I'he very nenro-fihrils upon which \patliy hases his doctrine were lirst well seen, as tlic author himseli" states, l»y Knptl'er in the tissues of vertehrates. The essential novelties in A]t;Uhy"s coiitrihutittns, in addi- tion to his nH)dilications of techni(jue and his woiuh-rlul de- serii)ti()ns of the details of the fihriUary appearances inside the protoplasm of cells stained hy his methods, whicli arc undoubt- edly of great value, are his deductions and hypotheses, of which all, in my opinion, maybe pci'niitted, at least for the present, to be judiciously skepticud. How does he know, for example, that the structures which stain violet by his gold method actually rc[)resent the conducting element in the nervous system ? It may be true, hut the Scotch verdict " Not ])roven " is here most api)licablc. Again, on what grounds does he sc[)arate the "nerve cell" so sharply as a ditfi'rent entity from the"gan- 'dion cell" and hov; does he know that the "nerve cells" ])uild the coiulncting element, and that the "ganglion cells " supply the force to he conducted y These mm/ be the functions of these two sets of element:^, but we must not neglect to point out that the evidence is not yet convincing. As yet 't is altogether too early to pass judgment upon Apathy's views; much work must be done by his methods by other observers before the exact value of his tindings can be properly estimated ; but were all his statements true, is there any reason to doubt that neurones will continue to degenerate as units, as heretofore ; that the i.'rvous systems of our cjiildren will continue to he built up during (Un'elopment of rcjteatedly dividing neuroblasis in the way with which we are familiar, or that (iolgi's method in the thirtieth century will have lost its power of demonstrating here and there a parti(;ular nerve unit or neurone in its entirety? Again, would the confirmation of the existence of continuous fibrils or fibril systems passing through a whole series of nerve elements necessarily militate against a unitary conce])tion ? I must say that I can see no rea- son why it should. Waldcycr, in his article in 18!)1, after dis- cussing the probable modes of conduction by means of the neu- I ^ii 5)1 !i I 64 TIIK NHIiVOUS SYSTEM. roiics, jiildcd, it woiiM sccin almost with pniplu'tic; iiisij^lit, the followiiif,' .stiitciiiciit : " If we ansunu! with CuAgi and H. llallor the existeiioo of nerve networks, the eoiieeption is somewhat modified, bnt we can still retain the nerve nnits. 'IMie limits be- tween two nerve units would then always lie iji a lu'rve network and not, anatomically at least, he exactly delinable with our pres- ent methods." We do not reMK\T OK TIIK XKl'llONH CONCKI'T. ♦ ;') may, liowevcr, Ijihhxhc in('a|ml)l(> of cxistoiKH! iiiiio|i(MuU'iit of lln>ir fellows. A iiiullJiHtllular iiulividiiai (person) liki^ u hiiinaii Ix'iii;; eonsisls of an a<;- t;refjate of l)illions of cells so intimately (■onne(;le(l witli ami I'elated to one another that tiic eonihined aelivities of the imlividual cells jjive the idea of unity, liut each cell nevertheless continues to have a life history of its own. In such a democracy, as it were, it is not surprisiuf; that there should \w iiiori)holoj,Mjrade as the eells which eonstruet a poem, or the perm cells, notwithstaiidinfr the fact that einbryoloj^y teaches (I) that the nerve cells are derived from the same f;erm layer that fj;ives rise to the ei)idermis. and ('i) that in all proliability every cell of the liody has within it. thou.irh latent, sidistanees endowed with the jiroperties aiwl potential eiierLcy which under sui tab oiulil ions woi dd make it capable of (level lo})in;,' into a complete ? 'M \'l .1'-. •f I ■k' / i>t human iieinir. «;h TIIK NKUVors SYSTKM. 'I* ■ J : I. 110 il<)«'«|ll!lt(' COIKM'ptioll. TIlC IMI'tlKxl of \ jssl t (K) llJIS rcVCUlciI (lilTcrciicos of iiitcrrijil .structiiri! ol (liU'crciit cell jfroiips wliicli iirc i'(|iial ill iinportiincc for [jiirposcs of cliissiliciitioii to tlio ex- tcniiil form rchitioiis discovored witli (iolj^i's stain. Of tlicsti a (Icscript ion is ^nvcwi furtlicr on. TiuM-c arc many ncnroncs wliicii, from the apix-arancc of a 8inj,'i(' cxainplc staincti l)la(M\ with silvi-r, permit an al)soint(^ de- cision as to their sourco. Thns we arc abU* at once to recog- nize tlio (H'Us of the sensory fijanj^lia (Fijj. :U), the <^ells of I'ur- kinjc in the cerehellnm (Kiconstrncted ' nerve fjell exhibited i)y (J. Mann at the sixty-sixth meeting of the British Association for the Advancennait of Science at Liver- TIIK KXTKHNAI, MoHIMIolJXiV ol' Ni:i|{(»NKS. <;<« |i*)(il ill IH'.H), iiiid at tlic iMcctiii^' ni' the Aiiiiloiiiisclic (icsi*U- Hcliiift, ill Kiel ill IS!)H. Tlic ImkMcs (tf the jicrvc cells viirv iiiucli in size, inciisuriiif,'" lidiii tour to a liiiiuirctl and lliirtv-livc inin'oiis aiiti niorc in Flfs|iiiiul (did IVom llic liiiiiiiin I'trtus, tliirly (•(•iitimctrcs lipiij,'. (Mt'tiiiid nf (iulKi ; al'lcr vmi l^cniupssrk. ) (liaiiu'tcr. Ainontf the vcm'v small ones arc the <:raniil('s of tlio olfactory hulb and the small cells of the cerehelliini, whereas the relatively huge iirotoplasmic masses, such as the larf^er cells of the ventral horns of the gray matter of the spinal cord and the spinal ganglia, or the cells of Purkinje in the cerebellum, are visible even to the naked eye. Starting originally as spheri- cal germinal cells, the cell bodies, jiartly owing to the mode of origin of their processes, partly for reasons at present not clear, later assume, in dilferent regions, very different shapes. The spherical s])inal ganglion cell, the flask-sha]>e;bt, is usually devious ; in fact, the irre<,nilarities in con- tour and direction are ini[)ortant distin<;uishin<; characteristics of this type of process. The character of the dendritic branch- iiifi: of the |iroto])lasmic process varies much in cells of ditl'erent parts of the central nervous system ; whereas in some dendrites eolu vcut (lire qu'avoe Ics inetliodos irinvestifjution (Imit nous (tis|i(is<)iis actiielleinoiit, on no voit pas de ooiitiiiiiito, on no voit piis (raiiastoiiidse.s entro los eloinonts iiorveiix. et par cinisoiiuont on no doit pas los aiiiiiottro." Hut this rule, as wo liave soon, is rolativo. not absolute. < t \l mi It 1 ?2 •|-|IK NKIiVolS SVSTKM. I ' ? llic Itrimcliinf; cotiimcnccs lit ii sliorl distimcc from flicir orij^in lit llu' nerve cell iiiid eoiiliiuies more or less rejiiihirlv mitil tlie iiii.-il tlivisions (leciir, in the deinlrites iif otlier cells ii iii:iiii IriiiiU iiiiiv csteiid tor ii coiisideralile distiiiice Troin the cell iiiid tlieii siidth'iilv hreiik up into ii l;irr is ehar- acti'ristie, for example, of the apical th-iidrites of the pyramidal cells of the ceri'liral coi'tex. 'I'he dejirree of complexity td' the briinchinj; varies I'lionnoiisly ; in some cells the dendrites are toleriihly simple and luil little hi'anched ; in others, the hranch- in;y than his first view of a successful impi'ciznat ion with the silver method of the dendrites of the rmkinje cells crowdin>; with their dense felt work the outer layer of the cerehellar cortex. The hunt' proloi)lasinic trunks coiniiiii' idV from the Hask-shaped cell divide and suhdividc with tropical luxuriance into widespread hiishlike masses, occupying a wide territory and increasintf the surface of the cell iiody, perhaps a hundred times or more. The sii:;- iiiticiiiice of this cerehellar forest, as it has hecn calhd, of tl.'ii- drites luiist l>c very ,u;reat, hut it has never as vet hecn .-lalis- I'lU'torily explained; al present, we can f(triii only hypotheses, lit hest very nnsat isfactory, as to its mi'iininj;. \'ery characterist ic, too, for the dilTercnt varieties of neu- rones is the relation of the dendrites to the surface of the cell body. Ill some instances, as in the motor cells »d' the ventral horns, they radiate out in all directions from nearly every re- jrioii of the cell surface. In the cells of the hippocam|)US, or horn (d" Animoii, one (tlluT fxamplcs iiii;j:lit lie ;j;iv('ii, Inil tliDSc iiiciil ioiird will siillicc to illiistnitc tlic iiiiportimcc of tlic orijfiii, ihiiuIkt, mid dislriltii- tioii of tlic dt'iidrilcs iis fai-tors in dctcniiiiiiiiij: tlic inorpbo- io^Mcjil clmraclcristics of :i },mv('Ii iiciironc. The occiirri'iicc of cell hodics nitirrly devoid of dendrites, tlie s(M;dled adi'udritie neurones, has to lie roco^Miizcd. Indeed, Flii. :tr>,- Ni'lll'iiiii'S ri'iiiu llic liiiiiKiciMninis (lioni of AiMiiKiiil ul' :i pii|i|iy two (liiys iilil. (Al'lcr l-'iillikiT. ) 'Two ityniinidiil cells ((iiil^i^ cill.s of 'r.vpc I) :iiiil (II II' fiisifonii (I'll (( iol^i's rcll of 'ry|ii' III mi'c shown. in invcrtobrat.i's, as von Leiiliossek, Ketzius, and A|i;'illiy have sliowii, th(>y arc very niiinerous and form in these aninnils no small proportion of the eonstitnents of the nervous system. In sneli neurones, however, the pyriform stem process shows near the cell many accessory liranchinss('k.) The roll Idxly is dt'Viiid ol' ilciidritcs ; the iicci'ssory hmii'. iit'S ol' the iiiaili prncfssfs arc l()()k('y otiicrs as collatcr.ils. jority of the neurones of the ganglia of the dorsal roots are histologically adendritic ; * though embryologically, and per- in J. Fl(i. :{". — l'liii'iiiiii(iiiyiM|ili lit' a iiiiriiial |iyraiiiiilal cell (Vniii the cfTcln'al cortex of tlic ;;iiinca-|)iK. (After I'.cikU'y. ) The siiifjlc-liraiu'licd apical dendrite and tlie liasii deiiilrites show distinctly the lateral hiids or "Kcniniujcs." The axom- is relatively smooth. ♦ Denclrilos hiive. Iiowever, been deinonstratod upon certain of the cells within the spinal jjanj,'liu. f- THE KXTKRNAL MORPHOLOGY OF NEUIIOXRS. 75 haps also physiologically, the axone of the periplionil sojisory nerve fibre is more of the nature of a dendrite. Microseopie- ally, however, it has every appearance of an axis-cylinder pro- cess, and indeed must be regarded as the axis cylinder of a meduUated nerve fibre. The dendrites within the central nerv- ous system are, like the cell bodies, entirely devoid of myelin sheaths. Another feature characteristic of the dendrites of some nerve cells deserves more than passing notice. Upon the sur- Fui. 3S. — I'lmtoinicrKKrapli olii iKunial I'urkiiijc cell t'nnn the Imiimii ('crcliclliir cortex. (Altral (•(irl<'.\ sliiiwiii}; llif arniiijjEt'iiiciit of tlic lalcr.il liiidsor kciiiiiiuIcs. (Alter Hcrklcy.) rone to neurone. lie ass(M'ts that in (tertain disesises, particu- hirly in certain intoxications, it is these " geniniulos " which are the portions of the neurone which tirst suffer, and lie has even sujf.irested that in paralytic dementia, for example, the early symptoms may be explicahle by assuming the destruction of large numbers of these gemmules. It has bee)i objected that these lateral buds are demonstra- ble oJily by (iolgi's methods, and that therefore one should hesitate before deciding that they are more than artefacts. * The selection (if the term " f^eiiiiiiules " to desifjiiate these lateral buds is tint entirely free from olijeetioii, iiiasmiieli as the same word was n^,•d liy Darwin in coiineetion with heredity as ti name for the minule elements which, aeeordiiif; 1,0 his theory of pangenesis, are {fivon ofT by the cells in dill'ereiil ])urts of the body, to be taken up later l)y tlie sexual cells. ,'!!! THE KXTKIlXAIi M()IllMI()Ii(>(}Y OF'' N'KUUON'KS. I I Hill * liiis recently stutcMJ that, iiltliout^li he tiiids tlieiii in iiini! cases out of ten, lie believes tlieiii to be artefacts represent ini^ "the cell end of an nnstaiinible nerve filament surrounded by a film of stainini^ cell plasm." From the constancy of their ap- pearance on the dendrites of certain only of the nerve cells, from their entire absence from those of certain others, and from the fact that they are most apparent and more shar|)ly defined in the most suceessful impre constitiitioii ol" j^niy inatttT. Hiiiiii. Loud., vol. xx, lHi»7, pp. l:it-i:{7. f Haiiioii y Cajal, S. Las Kspinas ColatiTalcs dc las ('('■liilas eld CiTcbro 'IVfiidas por I'l .\/'il de Mt-tilciio. Uevista 'I'limcstiai Micro-rriiflna, .Madrid, vol. i, fuse. 3 y :5, Agost'), IBiXi, pp. TilJ-CiG. i ^ ill C IT A ITER VIII. li: KXTKHVAL FORM Ol' TIIK A X IS-CYLIXDER PROf'KSSES OK AXONKS. II Theaxis-cyliixlor processes cr axoiies — Differential (■haraeteristifs of den- drites and axones — 'Die relations of tlie axones to tluM'eli bod_, F)en- (iraxones and Inaxoiics — Monaxones — Diaxones- — I'oiyaxoncs — Anax- ones — Seliizaxones — Modes of termination of axones — 'I'ciodendrions — The coverings of axones. TiiK iixis-eylindcr processes or axones * of nerve cells differ markedly in many ways from the dendrites. The appearances presented by an axone in (ioljji preparations are so characteris- tic that after a little experience the observer will rarely have the slightest difficulty in distiiifiuishing it from adjacent den- drites ; indeed, a few days' study with the microscope of successfully impregnated specimens will do more to convince the student of the differences in type of dendrites and axones tiian will numy pages of carefid explanation. f On analysis, however, the structures admit of differentiative description. The axone differs from the dendrite in its mode of origin from the cell body, in its contour and calibre, and in its course and mode of branching; further, if long, it is usually niediiUated, and also shows differences in its access- ry processes and in its method of termination. .Arising embryologically through a prolongation of the stem of the pear-sha])ed neuroblast {riilv iiifni), in the adult the ax- one conies off" from the cell body or from a deiulrite (Fig. 40), in the latter case usually near the cell body, though sometimes at a long distance from it, by a narrow wedge-shaped beginning. * KiiJliker's Netiraxon is well shorteni'd to tlie more simple nxohe, a term convenient and not liiiely to lead to any confusion. The designation ui'itrite has also lu'cn applied to this process. t It must in." Mdmittc ■ ' t \\ i i r r so TiiH \krvol:s system. 1 1 |i , ■! f, lit \ 1 !jii 1 1 ■ 3Ji ' m li ; I respect to permit easily of its ideiititicatioti (Fij?. 41). Wo are often deceived from its narrow calibre as to the volume of ati axis cylinder. 'IMiis may l)e as much as a hundred and eij^hty- sevon times that of tlie cell l)o(ly (Donaldson). Fl(i. 41. — Oiiljii's cell III' Type 11 I'rom llit' dorsiil horn of the tiny matter of tlie sjiiiiiil conl of the iicwliorii inoiisc. (Aft<'r voii liCiiliossc'k. ) Kvcii in siicli a (Icndnixonc llicaxonc is very easily distinKiiislialile from the tlendrites. Thu latter are oidy represented in part in the ilinsti-ation. The surface of the axono is smooth, its contour regnhir, tmd its course, :is a rule, direct, so thtit in most instances the trained eye can recognize it intiolgi preparations at first glance stand- ing out sharply like ii piece of hhu^k- thread on a white or yel- lowish l)a(!kground. The axones do not always, however, take the course to their destination which appears to be the shortest, In hi»i fr ! I I ■If Till': HXTKKN'AIi M()I{IMI()L()(iY OF Mll'UONKS. 81 aiul the <)riii y Cajal. ) .1. riisil'iiiiii cell ; />'. liiaiiKiilar I'cll ; r, aiKptiiir riisiloriii imII ; />. |i(p|yKimal cell w itii iiiiiiicniiis dcii'lrilcs and an llMiiic which divhh's rciicalcdly ; c, axoncs. occurs soon after its de])artnre from the cell, the total leufrth before c()in])lete loss of individuality may amount to only a few millimetres, or even to a fraction of one millimetre. On the other hand, the axoncs of some of the motor neurones are fully half as long as the height of a man. Hetween these two ex- tremes there is every possible degree of variation. The neurones with long axoiu-s (iuaxones of von Lenhossek, (iolgi's cells of Tyjte I, KoUikerV' /ifffroptx/fir ycrrciizi'llcH), as a rule, are monaxones — that is, they possess only one axone, Fi(i. 43. — Rjimon y Cajal's cell fioni tlic siiju'rHcial layer of the cerehnil cortex of a lo'tai cat. (.U'tcr Ketzitis. ) n. cell liody ; h. deiidrite : c. axone.s. though the spinal ganglion cells may, histologically at least {vide Kvp7'(i), he regarded as diaxoJies. There are neurones, too, which possess several axoncs. Among these, the so-called ])oly- axones, are the cells described by Ramon y ("ajal in the outer luyer of the cerebral cortex of certain animals (Figs. 4'^ and 43), from the horizontal dendrites of which as many as four or even 7 ', < /i n m !(::« (I 82 THE NKUVOUS SYSTEM. Hi i I! II I ■ i| !l; 'T . * St - f-- . -■= - -t r .- more hniiiflicri niiiy h{> {jivcii olT which possess all the cxtcnml chariictcrs of delicate uxoiies. Aeconliii},' to Uaiiinii y C'ajal, many of the syiupatlietic ^'aii- <,'lioii cells hiid down in the viscera — for exainple, those of Auerhach's and Mcissncr's plexuses — possess several axones. Anax( Mes, neurones whieli appear to he ahsolutely devoid of axis-cylinder processes, occur in the nuclear layer of the olfactory hull), in the retina ( Ki^. 44) {ffUvIvs ttiiKicri/irs of Ramon y Cajal), and, as von liechterew has pointed out, within the haskets of the Ki( . 45. — Aiiaxoiic Croin tlio basinet of a Piirkiiijc cell (if the (■(•rclicUar corlcx. (Mctlmd nf (idljii ; after vim lici'litcrcw. ) Purkinje cells of the cerehellum (Fig. 45). To axones which in their course divide into two equal or nearly e(|ual hraJiches — for example, the Y-shaped divisions of the central axones of peripheral sensory neurones after their entrance into the central nervous sys- tem — the name of schizaxones has lieen applied (Fig. 4(1). The ultimate terminals (teloden- drions) of the axones have been care- fully and exactly studied in great num- bers of instances, and nearly all observ- ers agree that, as far as ciin be made out by the method of Ci olgi, every axone TIIK EXTKKNAL M()UIMI()Ii(KiY OF NKl'UON'ES. 83 invuriiibly ends "free." Tlu' tcriniimtioii of a l)rancli of an uxono by mt'un.s of ii doliiiitt' I'lid arlxtrizjition iibout ti siiifjlo cell ( Fijr. IT) ociciirs, tlioujrb not so t'r('(|U('iitly iis iiumy writers would Iciid oiic to think. The coninioii inodo of ciidinj^ is by exhaustion throii;,di inidtiple division, tliis division iieinj^ often spread over (juite a wide Fic). 4(1. Fio. 47. Fl(>. 4askctwork. domain, so that the terniintd ])ranehcs of a single axone not infre(|uently come into the neighborhood of the dendrites and cell bodies of a considerable number of t.iJerent neurones. It may not be superfluous to emphasize this fact, inasmuch as a great nuiny diagrams hitherto pul)lished in text-books and not a few descriptive articles are entirely misleading ; the intimate interdigitation or interweaving of the terminals of one axone exclusively with the dendrites of a second neurone, so frequently pictured, very rtirely occurs, except in a few localities, as, for instance, in the olfactory glomeruli of some aninnds (Fig. 48). It is much nearer the truth to think of one neurone coming by means of the terminals of its axone or axones into contact with, '(. Ii /A ^ m t vj m im < I,! 1 1' li'" 84 TIIH NHUVOl'S SVsrKM. Fia. 4S, — Sclii'inc sluiwiiif; tlic relations in tlu' olfiictiiry ;;linii('nili tit" tlic axones III' the iiH'actciry nciirnnt's oftlu' lirsl order to tlie (len(lrile> of tlie mitral cells ill liinls After van (iehucliten.) Fid. lit. — Nucleus of termination of the sensory jiart of tlie nerviis trijreminus of the cat. (.\fter Meld. 'I'lie end ramidcatioiis ol' tlie sinjile axis cylinders are s<'en to he distriliiileil in widely separaled areas, so iliat impnlses coining alou}.' I lihre to the nindeus may come in contact with a larf;e nuuiher i)f neurones of tin mil order. scril)0(l ill various parts of the central nervous system. One of tlie most interesting of these is that shown in Fig. 53, which TlIK lOXTKUNAL M<>UIMI()L(»(iY (>K NKlUoNHS. H5 illiistrult's tlic iiKxlt' of termination of the so-called '• (•liinl)inj^ lil)res"iii the cerelu'llar cortex. Many otlier modes of termi- nation — for exam])le, tlio diselikt' expansions to I)e seen in Fi(i. 50. — A imu'li-l)niiiclif(l lilirc IVdiii the optic thiilamus of a mouse. (After Kollikcr.) Meissner's corpuscles and in the tactile discs in epithelial sur- faces (Fig. o;{) — might he mentioned. The curious calyxlike terminals (Held) of axones met with in the nucleus corporis trapezoidei are fully described and pictured in a subsequent i r 1V ih ■ivqi i Hti TllK NERVOUS SVSTKM. chapter (Soctioii \'I). It is to bo reiiiomluM'od that witliin the rentnil jhtvous system the tt'rniiiials of tlio axoiu's and collat- erals may, in some iustancos, como in direct coiita(^t with the bodies of other neurones [ride Fij^. 47), in other instani-es the second neurones are inlluenced perhaps maiidy throujjh their jirooesses. Tlie anatomical relation of one nerve cell with an- other is spoken of by Foster . ul SherringtoJi * as a sifiKijisis. f s * •[ Fid. T)!. — 'riircc end iirlidrizMtioiis of ii|ilic libvcs rnnii tliooptii' loin- of an I'Ui lir.vi) cliick. (Al'tcr Riillikcr. ) In the majority, althou<)ssess axoual processes which are, as a rule, devoid of such a pro- tective covering. In the majority of peripheral spinal and cerebral nerves this covering consists of a relatively thick fatty layer fortning tlie myelin sheath, external to which is a cellular layer, the muirilemma. Ilenle's sheath is the librous tissue ^ * Op. cif., p. i&l f l-'roiii crvv and Hwrw, i-liisp. TIIK KXTKKXAI. MOHIMIOLOCY OK XHrUONKS. ST often present external to tlu' neurilenuna. Witliin the central nervous system the myelin sheath is present, but the neurilemma appears to be absent, a fact which sjjcaks stroiifjly in favor of the view that the myelin sliea th is the result of tlie productive ac- tivity of the Hxone rather than of the neurilemma eel Is, as many have believed. The symi)athetic nerve tibres possess no myelin sheath, but are surrouiuled by a pr()teetin<( layer of lon^jf, flat cells formiuff a sort of neurilemma. It is not my ])urpose here to re- fer in detail to tlie histolo«j:y of these various sheaths of the ax- one ; they have long been care- fully studied, and are described at length, and, as a rule, correct- ly, in the text-books. I would oidy point out that the discovery of the fact that within the brain aiul spinal cord the axones of lu'uroiu's destiiu'd for dilTerent functions receive their myelin sheatiis at ditl'erent periods in developmental history, and its a})i»lication as a nieans of analy- sis of nerve tracts form the basis of Klechsig's embryological methods. liy means of the recent met hod introduced by -Tlu' so-calli'il " cliiiiliiny (if tilt' (•(■rtlicllar ciirtcx IVitiii tile lir.iiii lira I'liilil :i iiuinlli ami a hall' old. (Al'tcr K<>llik« r. ) 111 m , ..— t ' ■ ■ 4^' i I ( .. 1 •■} ! , ■ •■ ' t Fl(i. TiH. — nisc-sliapi'd cxjiansiDiis on iicivc titirilln' of tlii' piK's siioiil and their relation to ciTlain of tlii' ciiithelial cells. ( l''nini Sehiifer. after Itaiivier.) )/. nerve tihre ; »i. meniscus or disc; n. epithelial cell in contact with di.sc ; c, ordinary epithelial cell. 1 TT 88 THE NERVOUS SYSTEM. Eye muscle li! I' ■ li Fibre of Rotator muscle of ttie Iwfid Dorsttt Rvol Dorsal funiculus Reflex fiiilfi by way ifqrsol \ \ 0/ llievenlral horn I \ Commissure ( i-i* Fki. 54. — Dcvcloiiiiifr niyt'liii sliciitlis (ifditrcrciit afii's as seen tlirii inicn>sc(i|)c. Scliciiiatic. ' Al'lt r H. Ainltroiiii ii. H. Held, Aicli. I". Aiiiit. II. I'liysiol.. .\iiat. Atitli., Lcip/... IsiiH, Tat'. i\.> Tlic upixTol' the (wo (inures rt'prcsfiits till' rcllix |iatli lutwccii (lie acoustic aii Anibroim and Hold,* in wliicli tho poliirizatioii microscope permits the dctormiiuition of the younger and ohler of medul- lated fibres of nearly the same age, the sphere of ap})lication of the myelinization method of study has been consideraldy widened. In Fig. r)4 the sharpness of analysis made possible by means of the color dilferentiation is illustrated. Held f has tested recently by means of the polarization method the effects, of stimulation upon the progress of myelinization. The work done upon these lines belongs to one of the most important epochs in the development of methods of neurological investi- gation, and to the application of Flechsig's method to the study of some of the higher nerve centres I shall later take occasion to ref The portion of an axone nearest the cell body is with s^ i exceptions devoid of myelin, as are also its terminal ramifications (motor end plates and naked telo- dendrions within the central nervous system). Here and there in its course a medullated peripheral nerve fibre may suddenly lose its myelin sheath, be devoid of it for a certain distance,, and again suddenly be covered by it (Schiefferdecker). * Ambroiiii. II., uiid II. Held. MiMtriiKf /. fibre. It will be remembered that some of the fibres of the dorsal roots in their intramedullary course extend from the lumbar cord as far as the medulla oblongata, though it would be incorrect to calculate the number of (collaterals pro rri/ff, since, as has just been said, the cytodistal ])ortions of tlie 4ixone appear to be entirely free from accessory branchings. !)0 -A. ■f.l nil THE EXTERNAL MoltlMIOLOdY OF NEL'UoXES. \)l \'(»ii Lciiliossck, wlio has made oxliaustivo studies of tlie spinal eord, iiicludinj,' that of liuinaii beiiijxs (Fiji. 5,')), lias never ht-eii able to find eolliitenils in the fasciculus gracilis (iolli and does not believe that they exist there. Moreover, the munber of collaterals varies much, not only for axones of the same fascicu- lus, but also and more particularly I'or tiu' axones of ditl'erent physiological systems. In the dorsal fasciculi of the spinal cord, Flo. .^5. — Sclicinc showing' tli<' clinicnts nf the tir.\y matter (if tlic s])iiial curd. Oil tlic Ift't arc sliiiw II tlic tiTiiiiiial axdiics and ('(illatcrals ciitiriii}; tlic Kiay iiiatlir I'niiii tlic white siilislaiici' : on the rifilil arc to lie seen tlu' . ! !'l THE EXTEKNAI. MOlJI'lloLOCiV ()F NKIMIOXI-X !>8 orijrin, in tlii'ir nu'tliods of termination, anfl, most interesting of all, i)rol)al)ly in function. This now classification is destined to fjo far in ri-nderiiiir clearer the ])atln»loj:y of the s))inal cord — indeed, it lia.s already done much to elucidate many obscure problems connected therewith. The free ending of the collaterals like that of the terminal axones is insisted upon l)y those who work with the method of (jiolgi (Fig. -')()). After repeated division each little fibril runs out into a terminal end point which occasioiudly, though not always, appears slightly knobbed. The collateral may thus come in contact, by virtue of its end arborization, with the pro- cesses of several other lunirones, and here as before the diagram- matic representation of collaterals surrounding exclusively the cell body or dendrites of a single neurone is to be emphasized as misleading. V.'hile it can not be denied that such a means of ending may occur, it is at least certain that it is not the only one, nor, I think, the most common. The imj)ortance of recognizing the real method of termination becomes more obvious in the consideration of the simultaneous affection of a whole series of neurones belonging to one functiomd neurone grouj). As to Avhether col- laterals can be distributed in domains in which they can come into condu(!ti(m relation only with the side fibrils or collaterals of )/t'.s of other neurones, I shall have something to say when discussing the possible functions of the different parts of the neurones. (Jolgi distinguishes the side fibrils (Fig. 57), which run off from the axone into the gray mat- ter imnu'diately after its origin, from the regular collaterals which arise at a greater distance from the cell body. The form- er are non-medullated, the latter usually medul- lated. 1'hough morpho- logically there seems to he no very oljvious reason for such a divisi(m, von Lenhossek has recently expressed himself as of the oi)inion that the two A Via. 57. — Side filiril of (ioljji on tlic axone of a motor cell of the vciilriil horn of the spiniil conl. Tlu' arrow indicates tlie ccilnlifnj.'al (liicction. (AI'tcrvoM lAiiliossc'k. ) 94 TIIH NKRVOrS SYSTEM. 1- ' : ( 1 ! ( structnros niiiy bo of ditfcrt'iit si-i^fiiticiiiico in tlioir fuiu'tional aspects, ii siibjoi't to wliicli it will also he iicccssarv to return. Ill sum, then, tlie cell body, -ical indi'iieiidenei' of the nerve units. Kveii of the existence of ii solderinjj inter- substance we have very little evidence of a com incinji' nature. His assumes the presence of an unformed ground substance between the ditferent jirocesses, and suggests that this may be a constituent easily a tfected by intluences of a general nature, especially those of nutrition. On the other hand, von Leiihos- sek argues that no one has seen this intermediate cement sub- stance, and believes that it is possible to get along with the view wliicli looks upon the plasma stream or lymph stream as the only substance saturating the final plexus of nerve processes and filling ii[) the luiiiimal interspaces of the tissue, (hir knowledge of the lymphatics of the central nervous system is, however, deiilorably deficient, and there is urgent need for fur- ther researcli in this direction.* Kanion y C'ajaTs f hypothesis, according to which the penetration of neuroglia fibrils between the processes of neighboring neurones plays a part in the make and break of conduction paths, has as yet but little basis dependent directly upon anatomical oliservation. To lleld's views with regard to "concrescence" as a mode of interneuronal relation we have already referred in Chapter VI. In his third contribution to the structure of nerve cells Held J mt'ntions that by means of (iolgi's metliod he has been i * CI'. liiiiswiuiger, O. iiiid II. H('rj,'('r. Hi'itriir)-r)44. ■f liiiinuii y t'ajiil, S. Algiiims conjctums sohro ol inoeanisino anntomipo do la idoaciiMi. asdciaeiuti y atoncion. Ui'v. do nicd. y cinig. pnid. Madrid, 18!),'). veil, xxxvi, |)|). 407-508. Trarislatod into (Joriiiaii in Aivli. f. Anat. ii. IMiysidl.. Anal. Aldh.. Loiii/., Jahrij. 18!»r), Ii. 4/6, 8. ;{()7-;}T8. Cf. criticisin by V. K(">llikor. A. I'olier die? none Iiy[)otliese von Uainon von dor Bodou- liiiiiT dor Noiii-o,i,'lia-I''lonionto dos Goiiirns. Sitzungsbor. dor pliys.-niod. tlosollscli. ■/.. Wiirzlxirg. 18!)(», No. 8. X Hold. II. Hoitriigo znr Strnotur dor Xorvonzollon and iliro Fortsiitzc. Dritto Abliandlnng. Arch. f. Anat. u. Physiol., Anat. Abth., Leipz., Sup ■ i)loinontband, 1897, S. 373-ol2. :'! \ i Fl(i. TiH. — Pericellular networks l)elieve(l liy Held to he formed liy the tcvrniinals of iixoiies. (ioliii i>rei>ar:itioiis tVoiu a eat tweiitv days old. Sections 7lt n. thick. (.M'ter II. Meld, Arch. !'. .\nat. u. I'h.vsiol!. Keip/.. IS'lT, .\nat Ahtii., Su|)i)l. lid., Taf. xiv, Ki>;s. 5, 7, and S. ) .\. Cell wilh lu'twork from nucleus nervi cochlearis ventralis. The pi'ricellldar network surrouinls the whole cell ;iim1 a dendrite i)assiut; upward. The tilire a corresponds to one ol' the thickeued lil)res ol" the N. ci descrihed liv Kaniou y ( a.ja d llidd. Mevoud the thickened spot lihrils jro to join theiicneral pericellular iM'tworl H. Part of the netwofk aroniul a cell in t le nucleus uervi ves ularis lateralis (l)eiters). Held helieves that the IhickeuiuKs in the net- work ma.v ciM'respoud to the a^i^rejiatiousot' neurosouies whiidi stain in irou- Ineuiatoxyliu i)re])a rat ions. /, c, /. axones wlii(di help to I'orni tin network. ('. Part of the netwin-k around a cell ol' the nuch'us inrvi coeli learis ventnilis; the anastomoses of the eoiirscr suhdivisious of the fihres n ami ft and the larger swuUings of the threads of the network are clearly visiltle. ,._ vo i ]. . {. i TFIK NKUVOUS SVSTKM. 3 !^ i t fl "11 ,' L Slill iihlc to show the t'oriiiiitioii by tcriiiiiial ii.xoiics of lu'ricclluhir and iH'ridciidritic iii'tworks. This liiidiiijf is illu^Lriilcd in Ki;;. ;'(S. Tlic views of Apj'ithy us to the connection of many neu- rones with one unotlier l>y means of ik urotihrilla' have also l)een (h-alt witli in Chapter \'l. As this l)0(jk is heiiif^ put throu<(li the press a novel idea with re<(ard to intercellular substances luis been sugj^ested l)y Nissl.* This investigator has throujfh the researches of liecker, Apathy, and Bethe (cf. Chapter X III) recently been led to believe that certain fibrillary structures demonstrable by special methods within the protoplasm of the nerve cells are the elements actu- ally cojicerned in nerve functions. On the (ground of as yet rather niea iiniiiiiil tho fewer cell bodies ii\ ureas of ^'riiy matter of e(iual size. Now this discreijaiiey is attributed by Hainon y Cajal and others to the easily demonstrable disproportionality -,'i • .1-. « ', ,» •/ 1 J ... . ,•.♦,* ., II. 4 III. r^.: r':?^:- ■-V,f '(!;■;;.> .■■*<»W5i/. ■] IV. Fir., .'lit. U('i)np(liictiiiniil':i iili(pt;i';mu>f'a pcriicndiculiir section tlimiiuli the tip ol' tlic liciui of till' K.vi'i's rciitnilis iiiiliTinv lit' ;i licallliy adull iiiilil cliisc to till' I'iilx. StiiiiiiiiK '>y Nissl's inctliod. I. Layer [ r in cells. II. liayeiof l)yi'aini(ial cells, containing ".J - layer of small pyramidal cells i = ^. Mcy- nert's layer) ) '.i — layer of laiKe pyramidal cells i — H. Meynert's layeri. III. Layer of small cells . = -t. .Meynert's layer i. IV. Internal i(i> and exiernul (51 /.one of the layer of mediiUated til)res i = .1. Meynert's layer". The re- gion marked .") corresponds to the KaiiHlion-cell layer of Ilammarher;; and the region marke(' <> to the spindle-cell layer. ^ .Vfter K. Nissl, Munch, med. Wchnschr., Md. .iv, 1S))S. .S. I{l:i7. Via. ?,.\ of development of the dendrites and collaterals pertaininjj; to the cerebral neurones of the dilt'erent animals, but Nissl denies ftfi TIIK NKItVol'S SYSTKM. tlif !i(l(V|Hii('V <»f' tins ('xpliiiiiitioii. He asserts tlmt thiuiv of tlio structures wliidi !i|t|)('iii' to l)e, !ili(l are (leseril)e(l as, deiidriles of tlie pyraiiiitlal cells in (iol^'i prepuriilioiis euii not possildy Fl(i (H». l{)<|)i-iMlii('(iiiii (pC a |)1i(iti)j;i"!iiii t'nuii a iit'i'iH'ndiciiliir cDrticiil section thniiiKli til' siiimiiit nf iIk' k.vi'Us jii^l in I'nint iil' llic miIciis ciiiciiiliis nl' an ailnU (IcpK cliisc to till' t'alx. Staining liy tiir nicllKHJ of Nissl. I roitirai layer ''i-ee IVoni eells ; •^, siiliut in noway lioniol1; 14151 = layer of mednllaled lihres eorri'spondinn to 5 ■ ti in V\ t ti in I'M;;, til. That is. t in \''\k. (M> eorresponds to 5 in Kin. til. while ."> in Via. IMI - !• 1 After F. Nissl, Minudi. nied. Wchnsehr., Hd. xlv. isits, S. ltl^7, Kifi. 1. 1 1)0 dendrites tit till, iiiid maintains tliiit in any case in hiyer II (Mcynert's '2. and :{. layers) of l''i iifiiriiiics) and the ;,'liii I'dls imd their liltrils tlicsc pcciiliar iiitcr- cclliiliir stibHtiiiiccH do really exirtt, tho writor eont'esries that lie would not he iiiiieh surprised. Nor is it iiiithiiikahle that ititer- celliilar suhstaiiees in t he nervous system, if present, eoidd he ol" tlie hi<;hest funelional iniportanee, for in other tissiu's \vi- have not a little evidence that intercellular suhstanees play an impor- tant role in physiolo<(ical proiicHses. Ono has only to retnend)er tlu! Iluids of the hlood and the lihrils of the connective tissues, for example of tendons, to satisfy himself in this rejrard. No one, however, hesitates on t his account to hi'lievi' that hlood cells ami eonneetivo tissue eidls exist, and that they arc of parain(Uint importance; sinnlarly, even were interneuronal suhstanees of great funutiuiuil signiticancu denionstrutud in the nervous sys- I'lo. (11. -Tvcprodiictioii of 11 plmtDKniin of ii iiiTpciHliniliir section tliroiiKli tlio fcrcl)i-.il cortex of a inolc 1 nini. in front of llic crnciiil snturc close to tiu' falx. Staining; liy tile nietlioii of Nissl. 1 - exiernal layei' free from cells ; 2. cliaractcristic type of cell iirranKcinent in all cortical areas connecled with llie otfactorins. especially in the loliiis pyriforniis ; :? i = )l ot' I'in. (io, except, the thin cell-layer adjoinin;; the eell-fr<'e layer, wlii<'h reminds one still of a of Ki},'. til 1 ; \ '=.i of KiLC. tit) > : ") i -- I of \'\k. lit) i ; ti i = 5 of Kin. till k i After V. Nissl, Miinch. med. W( linschr., I5d. xlv, Isits, .s. 1(1^7, Kiu. 5. i tetn, no one surely would draw the tibsurd conclusion that nerve cells or neurones ilo not exist, or tluit they are of hut little functioiuil value. Brief reference only is necessary to the hypothesis of Rabl- V i ' ril '{ ill m 100 THE NERVOUS SYSTEM. I 11 HI iff 'W Ri'u'khard * and the modifications and extensions of it by Dn- val,f Tunzi, and otliers. J The whole doctrine by means of wliich sleep, anivsthesia, the phenomena of hysteria, donble person- ality, etc., are to be explained by amoeboid movements of the dendrites, or the so-called " retraction theory," appears to be based upon (1) the sinfjle o])servation of Wiedersheim with re- gard to anueboid movements of the processes of nerve cells in transparent animals like Lrjifothru Jii/((/iti(t and (2) the undu- latory movements of the distal processes of the olfactory periph- eral neurones. The idea has been severely criticised by von KiUliker,** and it is worthy of note that a theory so feebly sup- ported by facts has been so widely accepted and made the basis of a mass of clinical generalizations. * Uiibl-Iiiieklmrd. II. Siiul die Ganglienzellen nmohoid i' Einc Ilypo- tliese zur ^Mechanik psychisclier N'orgiingc. Neurol, t'enlralbl., Leij)/.,, Hd. ix (18U0), S. 199. ■f Duval, I\I. Hypotheses sur la physiologic des eentres iierveux ; t! eorie histol()gi(jue du sonmieil. C'ouipt. rend. Soe. de biol.. Par., 1895, 10. s., il, pp. 74-77. I Tanzi. I fatti e le iiiduzioui nelT odierna istologia del sistenia iiervuso. Kivista speriin. di I'reniatria, vol. xix (18915). * von Kolliker, A. Kritik dor Ilypolliesen von Rabl-Riickhard und Duval iiber ann'iboidc He\V(nable us to penetrate into the interior of the individual neurones, and to become ac- quainted with the structure of the proto])Iasm of which they are made up. Here we enter one of the most obscure domains in the whole of histology. We stand before the cells and their ultimate structure in the jiosition occuijied by histologists a century ago as regards the individual organs and tissues. The desirability of becoming conversant with the morphological Ha- lations existing inside the nerve cells becomes all the more lUl II 102 THE NERVOUS SYSTEM, ; i .iii fill 'ill I ; } M'ti M obvious when one tliinks of the possil)ility of iiltiTnately being able to trace u direct l)earinS m THE INTERNAL MORPHOLOGY OF NEURONES. 103 tlio fibrils which he described can easily be made out in fresh cells prepared in serum without any staininj^ or lixinjf reaj^ent, but that they are best demonstrated by bichromate solutions. He further added that the nucleus lies imbedded in the finely granular fibrillated material central part of the but does not ajjpear to in any direct connec- with the distinct til)rils covering the exter- nal surface. It was also his idea that the fibrils which compose tlie axis cylinder result from the collection into a group of the fibrils from the ar- borescent processes of the cell ; that is to say, tiiat the fdjrils which are seen traversing the substance of the ganglion cell do [•iginate in the cell, ly undergo a kind of Mni'nt in it, and then to the axis -cylinder or extend into the Fn.. fi2.-r,a„«lion ....11 fnmrtlHM.l.Ttri,. l.,i,.. "^her branched processes.* oi'tli.. iiiiiiii iif th.. t.irpc.lii iis iiictiir.d iiy In vlew of what We know Max S.'lniltz.'. <(. axis-cvliii.l.'r pr.iccss; j. ,, . , ,. ft. i>r<.t<.i(iasuii.. pinc'sscs. Ji<)w ol the structurc of nerve cells, and of what can be made out with the methods he employed, it is almost incon- ceivabh' how Max Sciiultze could have seen nerve cells as they appear in his figures (Fig. (12). That his vicAV, however, is sur- prisingly near that held as the result of some of the most recent researches can not be denied. The study of the bibliography l'« ,1 I ,1 I" Op. cif., p. 1:57. -SH I(t4 Till-: NERVOUS SYSTEM. I ili « ^ 1 II ;il since his time is rendered ditfieult by the faet that different observers have used different terms to indicate the same thiiij^ — in fact, nowliere in Iiistoh)r des Ncrvus syni- pathicus. Art'li. f. iiiikr. Anat., Hoiin, IJd. x, 1HT4, S. 208-241. f Key. E. A. 11. and (J. Hetzius. Studieii inder Anutoiiiie des Nervensys- toiiis imd (It's Miiidcj^ewclx's. 4to. Stockliolni. ISTfi. if Flemiiiinfi;. W. Meitriip- ztir Aiiut. ti. Einl)ry()i. ais Festfjalic fiir .1. Ileide. 1HH2. Roiin. S. 13. In this article the previous bibiiofjfraphy is thoroiiirldy rcvic'wcd. ("f. also, Teln'r den Ran dcr Spinalf^-atifjiicnzcllen bei Siiufjetiiieren. und Hcnierkinifjen iilicr den der ci'nl ralen Zellen. Arcii. f. inikr. Anat.. Bonn, IHitf), Md. xlvi,.S. ;{T!»-;5i)4. and Die Struclurder Spinalj,nuij,dien- zelieii liei Siiiip'tieren. Arch. f. Psyehiat. u. Nervenkr., Mcrl., lid. xxix (IH!>7), II. :J. S. !»6iM)74. * Miiller. Erik. Untersuchunfjen iiber 3. — Xerve cell from the re};i<>n of tho' ventral ('(ilumn of firiiy matter of tlie spiuiil conl of (iiidiis. Suliliiiialc tixatinn ; luematoxylin staining. (After Flcin- niinn- ) I'hc axonc is seen cniiiinn oil' from tlu' lower end of the cell. In the axoue and at its orinin in the cell body a liliril- lary apiK arance is seen. In the interior of the cell liody the spindle-shiiiied granu- lar masses are deeply stained, while lie- tween tlieni are Klennniufi's filirils, cut generally ohiiciuely i}° — 70° C) ; sections are then transferred to aniline-oil alcohol until dilferentiated. The process of differentiation is ended when no more coarse clouds of color <^o off into tlu' fluid. The section is then transferred to the slide, dried with filter i)aper, after which some drojjs of oil of caje- (lie X'crJinderungen der Nervenzollcii luii Faeialiskerii des Kaninciicns nacli Ausrc'issiiiig des Xcrvun. Allg. Zt,s('l)r. f. Psycliiat., etc., Herl., IM. xlviii {18yf-"!)'2), S. 197. — I'oljercxpcriinciiti'll crzcugtc W'raiRlcniiigcn an der. Vor- derlioriizelloii des liiiekeninai'kes be! Kaiiinelieii mil Deiiioiistralion iiiikro- .skopiseher I'Wiparate. Allg. Ztselir. f. Psyeiiiat., etc., Herl., Hd. xlviii (1891- '!>-), S. 07r)-6S'2. — ;\Iittlieilungeii ziir Anatoniio der Nerveiizelleii. Allg. Ztsclir. f. Psyehiiit., etc.. Herl.. Hd. I (IHiW).— Ueber Hosiii's iieiie Fiirbe- nietfiode de.s gesiiimiileii Xerveiisy.steiiis luid desseii iSeiiierkuiigeii iiber Ganglienzellen. Neurol. C'eiitrall)!., fjeipz., Hd. xiii (1H94), S. 98 ; 141.— I'eber eine neue Untersueliungsiiietiiducdes Centralorgausspeeiell zur Feststelluiig der Localisation der Nerveiizellen. Ceiitralbl. f. Nervenh. ii. I'syehiat., <'()- bleiiz 11. Leipz., ii. F., Ud. v (1894), S. ;5;i7-;344 ; also in Arch. f. Psyehiut.. Ik-rl.. 1894, Bd. xxvi, S. 097-013. — Ueber die sogenannten Granula der Nervenzel- len. Neurol. Ceiitralid.. Leipz., Hd. xiii(1894),S. (170; 781; 810.— Mittlieilungen uber Karyokiiiese ini eentralen Xervensysteni. Allg. Ztselir. f. Psvcliiat., •etc., Herl., Bd. Ii, 1894, S. 245.— Bernlianl von Gudden's liinianatomiscbe Experinientaiuntersuchuiigen. Allg. Ztsehr. f. Psycliiat., etc., Berl., Bd. Ii. 1894, S. 027-049.— Der gegenwiirtige Stand der Nerveiizellen-Anatoniie und Pathologie. Centralbl. f. Nervenh. u. Psycliiat.. ('ol)len/i u. Leipz., n. F., Bd. vi (189o), S. 1-21.— Feber die Nonienklatur in der Nervenzellen- anatornio und Hire niiehsten Ziele. Neurol, ('entrall)l., Leipz., TJd. xiv (lS9r<), S. (!' 104.— .Mittheiluiigen zur pathologisehen Anatoinieder Dementia jiara- lytiea. Arch. f. Psycliiat.. Berl., Bd., xxviii, 1890, S. 987-992.— Ueber die Veriinderungen der Nervenzollen naeh ex[ienmentell erzeugler Vergiftung. Neurol. Centralbl., r^eipz., Bd. xv (1890), S. 9.— Ueber die ortliclien Bauver- sehiedeiiheiten der Hirnrinde. Arch. f. Psycliiat., Berl.. Bd. xxix. 1897. S. 102o-1027. — Die llypothese der speeifischen Nervenzellenfunction. Allg. Ztsehr. f. Psycliiat., etc., Berl.. Bd. iiv (1897), S. 1-107.— Ueber Nervenzellen und grauo Substanz. Miinehen. ined. Wchnselir.. Bd. xlv, 1898, S. 988, 1023, 1060. * Centralbl. f. Nervenh. und Psycliiat., 1894. -.Jft aJg A- THE INTERNAL MOIIPIIOLOGY OF XEUUONES. 101 put are applied and the sections are again blotted witli filter pa)K'r. A few drops of benzine ar»^ i)oured on, then some benzine-colopho- niuni. and the slide is heated until all the Ix-nzine jius lias Ixsen driven oil". The dye is made as follows : Methylene bhic B. pat., .'{.75 ; Vene- tian soaj), 1.7*); distilled water or soft water, l,(Mt(t. Tbc diU'ercn- liatin ; the desired thickness can be obtained either by the iiddition of benzine or by allowing it to evaporate. In mounting, while driving olF the l)enzine gas. the material may catch lire, but if the llame be blown out iininediately, no injury is done, and the alterations produced by burning are i'issl perniits in some respects of a very ex- act morphological analysis of the bodies and nuclei of the cells. His method of elective staining distinguishes witliiu the cell bodies always two, sometimes three, constituents which are sharply separable from one another and easily recognizable. One of these ccmstituents of the protoplasm stains intensely blue by his method, and is spoken of by >»'issl as tlie stainable or visible formed part of the nerve cell.* The second con- stituent remains entirely ujistained and is spoken of by him as the imstaiiiable — that is, the visible unformed part of the nerve- cell body. In addition to these two constituents, in many nerve cells the well-known pigmentary deposits are visible.f Leaving * Nissl says: " Bruclistiicke tics fiirbbarcii, id <'.s/, des sichtbar gcforniton Thi'ilos (les Nervenzclloiikru-pors." Neurol. Centralb.. Lcipz., Ikl. xiii (lHf)4), .S. 07(1. \ Tilt' .siil)staiices wliicii stain black with osniic acid in many nerve cells, well known to all who have employed the method of ]\Iarclii in the stiuly of Iminan nerve centres, have reeently been made the oljjeet of especial re- search by Rosin. Cf. Rosin. II. I'iin Reitrag zur Lehre vom Ran der Gaiifjlienzellen. Deutsche mod. Wchnschr.. Leipz. \\. Herl., Rd. xxii, 1H!)0, S. 40.')-4))7. Similar structures are abundant in the gan.uflion cells of the monkey, as 1 can assert from specinu'us shown to me by Dr. Melius. Tills jiif^ment appears its litrht yellowisii masses in the large motor cells of the ventral htirns of the spinal vnn\ and in the motor nuclei of the me- jl ' ''% I i II i > il .U '^^ 'V, -I ^1 III 1. 11 m. 108 TIIK NKllVors SYSTKM. tlic ])ifi:nuMit for tlio tiino }»i>iiijr (tut of t'oii8idoration,mii('li is to he k'iinuMl from ii study (»f tlu' cliiiructer.s of tlic staiiuibk' portion iiutl its ri'liition to tlii' iion-stiiiriiibU' portion of tlu' cell body in ditferent cells in various parts of the central nervous system, and upon such studies Nissl has built up an elaborate classifica- tion of nerve cells. This will l)e referred to in the next chap- ter. Any one who takes the trouble to use Nissl's method in the way that he has directed can easily convince himself of the relial)ility of his descriptions. The stainable portions in tlie nerve cells show a series of ditferent forms ; smaller and lar<:jer granules of regular or irregular shaj)e, groups of granules, and rows of granules can be made out. Often the stainable nuisses are arranged in threads, sometimes smooth, sometimes rough, and varying in thickness, course, and length. Often larger structures, regularly or irregularly shaped, arc to be seen, Avhich stain with varying degrees of intensity. Some of them appear homogeneous ; others show an internal constitution, complex and difficult to describe. Of the larger bodies, tliree varieties are especially iu>teworthy : (I) The so-called nuclear caps {Kvnikappen)^ stainable masses which possess the form of regular, sometimes of irregu- lar cones, each hollowed out internally like a cap, correspond- ing to one pole of the nucleus \\\)o\\ wliich it sits. There may be two of these nuclear caps within one cell body, correspond- (hilla ; ill tlie j»yraiiii(liil cells of Betz in the cerebral cortex: in the colls of the nucleus dorsalis and in other parts of the central nervous system. Curi- ously enouf^h. when the pij^inent is present in nuvsses in the nerve cell tlie tigroid aijgi'ejjations appear to beaiisent from a portion of the protoplasm in which the pigment is situated. The jiigment here described is not identical with that of the locus co'i-uleus. the substantia nigra, ti.e substantia ferruginea^ etc. The relation of the substance or substances here concerned to what we have been accustomed to look upon as pigmentary deposits should be fur- ther investigated. Uosin believes that the pigmentary substance is allied to fat. It not o stains black with osmic acid, but if the tissue be previ- ously treated witli alcohol and ether the osmic reaction, it is said, is not ol)tainabie. Acetic acid has no effect upon the reaction. According to I'ilcz, Obersteiner, and otliers, Hie light yellow pigment appears at different peri- ods of life in different n, e cells; thus in the cells of the spinal ganglia it is first found at the sixth year, while in the spinal cord it appears first at the eighth year of life. As age advances the amount of pigment in the nerve cells gradually increases, a fact entirely consonant with the idea that the l)igment is a result of catabolic metabolism. Van (Heson refers to the pig- ment as " metaplasm granules." m 1 if fc/i THE INTEUNAL MOIilMIOLOU V OE XErUONES. lot) ing to two opposite iiuolcar poles, and oeeasioiuilly, aceonliiijr to Ni.ssl, cells are seen in whicli three sueii caps are i)reseiit. (;5) So-called wedf^es of division ( \'frznri(/i(ii(/K^-('!/rlii),ntii\n- able nnisses which fill completely the an<,'le at the point of divi- sion of u nerve-cell process. {'.]) Spindles, oblonjf or s))indle-shai)e(l stainahle masses which are thick in the middle and l)ecome thinner toward the end, occasionally rnnniiig out into threadlike forms. One-sided and double-sided spindles exist. Any one of these forms may be vacuolated, as has been pointed out by Nissl, von Ijcnhossek, Held, and others. Von Lenhessek, who has also stronijly opposed the idea of a fibrillary structure for nerve cells, has in the second edition of his book * given us a very accurate description of the appear- Yui. M. — Lai-fii" motor KaiiKliim cell from the ventral liorii of the spinal cord of the ox. Tliionin staining. (After von l.enlios.sek.) nnces within the cells of the ventral horn and the cells of the spinal ganglia. Ventral horn cells, examined fresh or in an in- different Huid, show little if any structure. The proto])lasm is yeen as a smooth, glistening, indistinctly granular substance in * von LenliDssi'k, M. l)er feiiicrc l?aii des Xervensysteins im Lichte neuestcr Forschungeii, 2te AuH., Berlin, 1895. I' 1 i i r r ;[ 1 ! \' i , 'i I ' M i 10 TIIK NERVOUS SYSTEM. l!) 1 ;! I : wliicli soinctinios n sli<;Iit concentric iirraufrcJiiont iiiiI{IMI()I,()(iV OF NKrUoXHS. II tions. Do Qucrvain * has sufrfjosted that all tlic chromopliilc bodies n'])ro8ont iniiltiitlcs of line /ininiilcs, and von Leidiosst'k admits that tho bodies are rarely liiii'ted by a sharp line, imt that they, as a rule, show irregular, ()rten jagg*'d, uuirgins, and often look jit their borders as though they were broken up into small granules. Ho refuses to admit, however, that all such bodies represent aggregations of minute granules, a j)oint al)out wiiich more will be said when the work of Held is discussed. \'on Leidu)ssck has studied with care the relations of the Nissl bodies in tho dcndritos, and finds that from always being few in nund)er thoy cease to appear at a certain distance from tiie cell body, and as soon as the dendrite has reached a certain thin- ness. Jn tho deiulrites, their shape and general appearance are quite different from those of tho interior of tho cell body ; they form long, narrow, straight, rod-shaped masses, often sharpened distinctly at the ends, so as to form definite spindles the long axes of which are ])arallel to that of the process. The vari- cosities on the dendrites in (Jolgi preparations von Lenhossi'k holds to be due to superficial collections of chromophile sub- stance. f His description of the origin of the axone is particu- larly clear and accurate. Schatt'er J was the first to descriljo tho peculiar behavior of the axono and the adjacent portion of tho cell body as regards Xissl's staining. The axone itself, unlike the dendrites, is en- tirely free from the stainable substance of Nissl, as is also the portion of the cell body immediately adjacent, known as the axone hillock. This hillock is nuirked oil' by a tolerably sharp curved plane from the granular pr()toj)lasm of the cell body, and shows at its margin not infrequently a layer of especially fine granules. With Kronthal's method, the axone and axono hillock stain intensely in methylene blue, very much as in the vital staining of Khrlich. Hat Honda found that when specimens thus prepared were cleared in (Toosote the axone and axone hill- * De Qiiervnin. Frit'.. Uober die Vcriliulerunjren des C'entnilnervensys- tems bei experinientolier Ivachcxia thyreoprivii der Tliiere. Arch. f. jiatli. Anat., etc., Hcrl.. I?d. cxxxiii (18i);5), S. 481. •f Tlie writer has froqui'iitly ol)tiervc spherical or eili))tical in shape, often larger than the nucleus, and do not represent striuitureless Fiii. (iti.— Spinal Kaiijjiioii cell of Hiiiki ('iitfslninin. ( \ftvr Hulicr. ) A siilc til>ril, II, is to Ih' sci'ii (liviiliii<; into tlin'c Itraiiclics, carli of wiiicli tcnniiiatcs in an fiid disc ; tlif ricar /.oni' of |)i'oto|)lasni, /*, Ix'nratli two of tin- discs is shown spiices tilled only with Ihiid, but contain nortiial ground sub- stance, and besides often show in their interior a few gnmules widely separated from one another. The exact natnre of these 9 I" '.. "iM ■:'i^ iiH t i i ' i i 11 + THE NKIIVOUS SYSTEM. Viicuolc-Iiko s|)()ts is us yet not (^Iciir. It is not iiiipossiblo tliat sonic of t hem correspond tollic position of Icrniiifiil end discs of side librils coming olT from the ji.\(»nc and ninninjj; IkicIv to the cell body, such us hiivc^ been (h'scribed by ilubcr, of Ann Arbor,* in the spinal ;,'an^lion cells of the froj;; ('*''K' *"•")• "t* states that there is usually foniul a clear zone of protoplasm surrounding the expjinded end of tiie ])ro(!e8se8. * llulicr. (i. ("ml. The Spiniil (iaiigliii of Ainiiliihia. Anal. An/,., Jena, l? crlls. Nissi, lias spent several y<'ii'"« in f'i<' niost, exact investi- jjatioiis of the nerve cells in the diirerent parls of th(f nerve centres of man and aiiiinals, and has conn! to the eonclnsion that definite types or varieties of nerve cells exist, varieties which are constant not oidy in tiie same animal, hut often exist characteristically in hoinolo<^oiis localities in a whole series of animals. li(> has had some ditliculty in finding suitahle desig- nations for these types of nerve eells. In the present st'iU; of our knowledffe, a. nomenclature l)ase(l upon function, except, perhaps, for a few cell cateojories, is not just ifiahle, and N'issl has been compelled to classify th(! cells accordinjf to their mor- pliolof,ncal characteristi(!8. According to him, all the cells in the nerve centres, excu'pt the so-called vhrdiiiopliiU' nerve cells, can he divided into two main classes. 'Pile first group includes the nerve cells which possess a well-marked cell body which surroumls the nucleus completely on all sides, the TjrotoMlasm having a distinct contour. These cells Nissl (uiUs xomninrlironh' nerve cells. To the second group (subdivided itito two groups — cyto- chrome and caryochrome) Itelong those cells in which in Nissl preparations tiie nucleus is most in evidemu' ; the nucleus has a clear contour, but only indications, as it were, of the cell body are present, an apjiearaiice due either to scanty d((velopment of the cell body or to the predominance in it of the unstainable substance. These (;('ls often look as if they were naked nucUu, though by ("olgi's method it can be shown that they may p(»s- sess definite axones and demlrites. In some of these ciells the 115 : 'hi ■ If ^i 110 TIIH NHRVOl'S SYSTHM. r I II i H st:iiiml)lp substance may l)c present, tliougli wlien it is, it is very unevenly distributed, heini,' eollec^ted ut definite points in tin; eell, the nucleus apparently heinjif only partly surrouiuled by protoplasm. Such cells are to be seen in the substantia f^ela- tiiiosa of Rolando, ^s'issl su^j^ests that the nerve cells with an ill-developed cell body, in which the nucleus ap]iears to be in- eonipletely surrounded and does not exceed in size the nucleus of a i;euro>;lia cell or of an ordinary leucocyte, be called "y/v^//- tih's " ( Ki'iniir) or fiihirhrdiiir nerve cells. These cells are present in great numbers in the granular hiyer of the ci'rebellum. There are dill'erent varieties of these cytochrome cells, those in the // / // III w \ v ■ I i I''l(;. (17. — Nt Tvc cell iVdiii (illii(li)i> liiillxiC liililiit. ( Al'tcr Nissl. ) SoiiiMliiclinpiii.- Ill TVc cell (pf llic Mrkydcliiiiiiic Viiiicly in llii' piiiaiiyUnoiiiiiipliims iniKlitinii. ' ■ere])ral cortex, those in the cerebellar cortex, and those in the olfactory bulb, for example, being l)y no nutans i(lenti<'al. Tlu' secoiul subgroup of cells in which the cell l)ody is only indicated, but in which the staiiu'd nucleus is of the size of that of an ordinary nerve cell, or al any rate is larger than that TIIH INTKHNAIi MoHI'HOI.OOY OF NErROXKS. 117 of ii lU'Ui'oj^liii ('I'll, Nissl calls ctiri/dc/inniir iiiTvi' cells. (M' these there are also distinct varieties — for example, those of the substtintia gelatinosa of the spinal cord, and those of the y^^ X V\^^<. fiK. — Nerve cell fnim (Icivsnl nileleiis of iiroxiliiiil iKivtinii cif iiiediillii of nihhit. (Afler Ni>sl. ) Siiiiiiiluilirniiie liervi> cell of enMlkyncliiiiiiie iype ill iipykiio iikh'IiIkiiis ('(intliliiiii. nected in the cull body by (U'oply staiiu-d wry thick bridges, so that a further connected network of very deeply stuinable sid)stance is observable. Both enarkyochronie and ainphar- kyochronie cells are, accordin<^ to Nissl, widely (listrilttitcil throutfiiout the central nervous system. ^JMie former occur in the sjjinal cord, but are most munerous in the large dorsal nucleus at the proximal end of the medulla (Fig. (iS). ,.'\ ;iiri \ Kid. 70. Fio. 71. Flo. 70. — I,arf;«' <'t'n IVoin .\iimioir.s liorii of i-.iMiit. ( Al'tcr Nissl. ) Siiniiitocliroinp nerve cell ol' stieliofliniine variety in llie iiyknoinoiplmns eonditidii. Fl • / iicrvf cill of the iirkyiisti.iKP- Lastly, as a fourth group of chroiiic variety ill till- iipykiiti- , ,' n i-. i morphoiis coiKiitiiiii. somatochrome nerve cells, ^issl * Nissl in a rccriil uiliclc (AUg. ZtsL'lir. fiir Psychiat., Hcrl., I5il. Uv (1807), S. 101) liiis {fiveii up the term " arkyostietiochroine " and iiiehides IIk^ cells formerly clussud in llie arkyDslicliochromu groiiii among tho arkyo- iiH ^^ TIIK INTKHNAL M<>l!IMI(>L()(iV OF XKl'HONES. I'Jl (U'scrilu's tlic {^ryoclironic (ypv) type, in which the stiiiiiahle eoiistituniit of the cell Itotly is ciitirt'ly iriudi' up t)l" siiiall j:;rim- iiUis. The {^runules iir(( not (listrihutcd, however, at random in the cell hody, but tend to form threads or h('a})s, so that a dis- tinct habitus can be attained. Nissl does not jiive pictures of cells of this type, but mentions that they are particularly, though not exirlusivi'ly, found in the corpus striatum. The whole series of types as revealed by his method nniy l)e classified therefore as follows : A (Jitori' I. SoMATOciiuoMi; Xkkvk ('i;i;ls. — Cells in which the cytoplasm surrounds the nucleus completely and exhibits a distinct contour. A. Arki/dchronK' /irrir rclh. The stainable substance in the cytoplasm appears to be arranged in the form of a net- work. 1. Type of enarkyochrome nerve cells. 2. Type of am})harkyochrome nerve cells. ;{. Type of arkyochrome olfactory nerve cells, etc. B. S/ir/iorltroinf iicriw ci-Ux. The stainable substance in the cytoplasm is arranged in the form of strij)es running in a similar direction. 1. Ty])e of motor nerve cells. 8. Type of large stichochrome cells of Amrnoji's horn. 3. Ty})e of stichochrome cells seen in the cerebral cortex. 4. Ty])e of nerve cells in the sj)inal ganglia, etc;. (J. Arh-!iosfirli(trlirt>nii' nrrir ri'lls. Of these, uj) to the pres- ent, only one type has been distinguished; this would now be classed by Nissl among the arkyochrome cells. 1. Type of I'urkinje cells of the cerebellar cortex. D. (iri/dc/iroiiic nerve reli.s. fjRoup 11. All Nkkvk Cklls not fallixo in Choii' I. A. Cjilurhroiiie nerve cells. Oidy trac^es of a cell body are {)resent. The nucleus is of the size of the nuclei of ordinary leucocytes. 1. Cytocdirome cells of Type a. 2. ('ytocihrome cells of Ty])e ^, etc. (^hromc pcUs. Ry far the majority of all the norve cells in the body fall in the arkyochrome group. X. (, I m ^ , 1 ' 'i ' ^ ■ ! I: lij 1 ' 1' til? ; h\ 122 '^'HE NKIIVOUS SYSTEM. Ji, (hri/or/iromr uorve mllx. Only traces of ii cell body are prost'iit. Tlie nucleus is of tlie size of onliuary uerve- cell nu(!lei, and is in every case lariissl upon the importance of his " staiiuible substance," which we now have some reason to believe represents only a porti(m of the supply of food stuffs in the nerve cell, snch a classifi- cation can scarcely hope to stand the test of time. It would b(^ as though an architect should attempt to classify houses ac- cording to their pantries and cellars, or an anthropologist to group men as types according to the contents of their stomachs III ;. ;u THE INTKKNAL MOKlMlolAXJY OF XKl'UoNKS. 123 and intestines — niothoda of catiilo'juiiiji usi'fiil ciiniiffli at times, perliiii)s, but scarcely to be b)oke(i upon as ideal or permanent. Ni.ssl early jjoiiited out tliat tbe sin^jle tyjx's of nerve cells may uuder certain circumstances sliow dilTerent staining rela- ti(»ns ; * tlie individual members of a given group of cells l)e- l(mging to one type may bi' palely, moderately, or intensely staiiu'd. Tliesc dilfcrences appear to depend uj)on the concen- tration of the stainabh^ substance in the cell i)ody. '. si con- secpiently designates the extremely darkly stained cells us pjlk'nuniorplKtHs cells, or cells in which the stainahle portions are arranged relatively most closely (ttuki/os), while the very feebly stained cells he names fijn/k/i(iiiH)r/i/ionf< — that is, ^.I'Wa in which it is characteristic of the staining that the stainable masses are not arranged close to one another, but are tolerably widely sep- arated by the non-stainable constituents of the cell body, in- termediate stages Nissl groups iiAjxinr/if/li'i/oiHor/i/Kiiis. Klesch f described these appearances, speaking of r/iromaji/ii/ic cells ami rJt rdtiiop/ioijic wlhiiHwoW as transition forms, and attributed the (litferences to variations in the interiuil chemistry of the cells, which depended in part, he thought, upon ditferences in the de- velopment, in part upon ditferences in metabolism or of function. Xissl goes further, and mentions that not infrecjuently the nucleus shows modifications which correspond in greater or less degree to the staining intensity of the cell body — for exam- ple, in the apyknomorplious cells the unstained nuclear juice is relatively more abundant than in the pyknomorphous exam- ples, in which, as a rule, the nuclear frainework and the stainable parts of the nucleus generally are relatively more abundant. This holds, he asserts, not only for the somatochrome cells, but also, though in less degree, for the caryochrome and cyto- chrome cells. A curious and puzzling phenomenon is met with in the so- called cliroitiopliik'X nerve cells (Fig. T-\). One sees often. * Alls, /^tschr. f. Psyp'ii'it.. Ht>rl.. Bd. 1. •f Flcscli. M. I'oIhm- (lie VcM'scliicdonlioitcn im chemisclKMi Vorlmltcn dcr XiTvi'iizi'lliMi. Mittli. d. iiiiturl'. (icsollscli. in Horn (ISST), Xr. 1 H)!)-ll!)4, S. li)2-li)!). Hi^in, I*. Ibiller. t88H. X Tlio word c/ininiopln'le is hi>ro nscd in tin' sonsc in \vlii('li Nissl cinploys the torm ('lirttinophiliv (Xissl. Allj,'. Ztsclir. f. Psyclii!it..<'tc.. Mcrl. (iHlHi), I5d. Hi, S. H). WliothiT or not, this is the sensi- in which tht; word is employed hy Plesch and his pupils is not dear. "m ■V:' !| •iiPi 124 TIIK NKIJVOI'S SVSTKM. I I ■ ;»♦ [ 1 ' .< , i : !! •,i\(me;irs to l»e eveiilv (iill'used t liroii;_'lioiit the cell ho substances contu'rued, and secondly, that certain iund dyes will stain them intensely, objections which he believes uj)set entirely osm s view nased H that on IhrlicI 1 s "olor tl Dasic (lyes, iiKe m( lik •thvlt u'or d tl" It IS certain cue /.ue and tluonin, stain very beautifully the Nissl bodies; indeed, the nu^thod of Xissl de- l)i'uds u])()n this quality; but Nissl contends that the term lUtsiipliilii' A\o\\\{\ be used oidy in the sense in which it has been previously deliiu'tainin;4' thin sections that much of the increase in our knowleilji'e of the nature of the staiiiable substances inside the cell has resulted. In order to study ordinary palholojjfical alti-ratioiis in the cells, however, .sections from six to twelve or even thirty microns in tliickness utTord the most .satisfactory r(>sults. Held fa.stens the parailin se<'tion on the slide with dilute alcohol : the staininj^ Huid consists of ecpial parts of Nissl's solution of methylene blue and .soap and a tive-pi'r-cent acpieous .solution of acetone. T\\v .sections are heated in this mix- ture until all smell of acetone has disappeared. (Held stains tirst with a solution of erythrosin. the erythrosin servinji' to brinji' out the other constituents of the cell body, the iioii-stainai)le substance of Nissl ; for tlie study of the Nissl bodies alone this portion of his nietbod can lie dispensed with.) The sections, aft(>r stainiufj', are allowed to remain in the blue solution until it has cooled, and are then dilVerentiated in a one-tentli-of-oiie-jier-cent solution of alum for from a ft'w seconds to a few minutes, accordinj;' to the thickness of the section. The sptH-imens are then washed in water, debydrjited quickly in absolute alcohol, cleared in xylol, and mounted in beii- ziiie-colophoiiiuni. H(dd used as a fixinsr ajrciit sometimes ninety- six jier cent alcohol and sometimes picrosulphuric a<'id, as the latter shrinks the jirotoplasni less. Tn usiiiy this lixini:' ajrent, however, very small jiieces must be em])loyed, as it penetrates with dilli- culty. It has been stated by some that staiiiiiiji- with tlie blue solution for twenty-four hours in the cold mj)loyed. He has obtained his best results by staiiiiiifj: for twenty-four hours at a temjierature of MT' t'. Another excell(>nt modilication of Nissl's method is that of Mann, of Edinburj^^h.* Sections of sublimate tissues are stained with a concentrated a(iU(>oiis .solution of toluidin blue. They are then diU'erentiated, and may lie counter-stained if desired. The * Miuiii, (i. Uelior (lie Heliiiii(llim,>r dcr rt'iizcUoii fi'ir expcriiiii'iitcll- hist()l(>;;is('lio UntersiiciiungLMi. ZL^^clir. f. wissLMiseli. Mikr,, 15nisi:li\vy„ Bd. xi (US04), S. 4T!t-4y4. 'ifil 130 TIIK NKIIVOUS SYSTEM. ii !'■ ! ilir I i( u m t<)hii(lin-l)lu(' iiiotliod lias also been iisod by von Lonhossc'k * witli satisfaction, and rcci-ntly Harris, of Pliiiadeli)]iia,+ lias publisiiod an article in wliich ho jjives a innnber of interesting details with re- gard to his modifications of this method of staining. Held finds in sections from one lialf of a micron to one mi- cron thick that the tijjjroid bodies present an ex(|nisitely granu- lar structure (Fig. 75). With liigli pow- ers tliey are seen to be made up of masses of granules, some of the constituent granules ])eing very small, others very coarse. They have a rounded form, and when not too close together ajjpear in rows and radii. In some cells, where the constituent granules are very close to one another, a granular structure is recogni- zable only in extremely thin sections with the aid of strong immersion lenses and favorable illumination, liut Held , ,-,.,., , • maintains that in reality all ar(M()mi)osed •<:^h. #..^j ot granules. In some cells the granules, -v*'" instead of being grouped in clumps, ap- Viy,. 75. —('.11 of vontrai p^..^. jq \jq more or less evenly distributed licini cif j;i"iyiiiiittcraraltiii. See- .•' . ^ tiimsiiin tiiiek- are not In contact with one another, but iiess. Stained with ery- ■ i i i i • i i-i tlirosin and iiietliyleiie 'l^'t* nnl)cdde(l HI a coiigulumlikc niiiss which stiiins violet iind is easily distin- guishiible from the bright blue of the griinules pro]»cr and the red of the ground substance — that is, unstainable substance of Nissl — lying between the tigroid bodies so that lleld dcscril)es the tigroid bodies as being uukk' up of two constituents, one griinuliir, the other coiigiilumlike, with sometimes a third — ntimely, the vacuoles. * von Lenhossek, M. Uebcr den Huii dcr Spiiialgunglieiizellen ties Meiischen. Vortrag iiuf der Wiuidorversiuiunlinig siidwcstdeutsclier Neii- rologoii. Madeii-15adoii, IHJIG. Areli. f. Psyeiiiatr. u. Xeiveukr.. Herl.. IM. xxix (1896-'9T), S. lUO-IiSO. t Harris. H. P. Two New ]\rc'tliods of Staining the Axis-Cylinders of Nerves in the Fresh State. Some Microi'liemieal Keactions of Toluidiii- Blue. Philu. M. J., vol. i, 18!»«, pp. 8!»T-!)(K>. Iiliie. Tlie Nissl bodies are seen to lie made up of masses of miiiut<' unin- nles. Tlie liiM' f;raiiiila- tioii of tile Ki'oiind siili- staiiee is also aiiiiareiit. to iir TIIK IXTEHNAL MOKIMlOLOOY OF NEUUOXES. I'M Held (k'scril)i's in detail his study ol' fresh - in alcoiiol tissues. Thus, he found that the ti- groid bodies are insoluble in dilute and concentrated min- eral acids, in aeetic acid, boil- ing alcohol, cold or l)oiling ether, and in ehloroform. On the other hand, they are easily soluble in dilute and concentrated alkalies. With pepsin-and-hydrochloric-acid. digestion he found that the ground mass of the jiroto- plasm vanished and that the tigroid bodies alone re- mained undigested (Kig. 7(i), the reverse of what octmrred on treatnuMit with lithium ( Fig. rr). The tigroid bodies yielded no reaction with Mil- Ion's or Adamkiewicz's rea- gent. Held obtained, how- ever, slightly positive results with Lilienfeld and Monti's mieroehemical test for phos- ])boi'us, and a considerable «|uantity of the gray nnitter of the s])inal marrow after digestion with pejjsin and hydrochloric acid examined by Siegfried, of the physiological laboratory of Leipsic, showed the presence of phosphorus. Held concludes, therefore, from these various reactions, that the Nissl bodies belong to the group of the nucleo-all)umins, a view whifdi agrees with the investigations of Halliburton, who found in the gray matter a nucleo-albumin which coagulated at from 55° to 00° ("., ami which contained as much as 0.5 per cent of ])hosphorus. We have here in Baltinuire tested the tigroid masses a nund)er of times for the presence of iron by Macalluni's method, always with negative result. Warring- I'"i(i. 77. — Ncrvo ct'll t'niiii tlic };i"i.V iiiiittcr of tlif liniiliiir ciinl nt' tlic i>\. Alcolml tixatidii. 'rrcatiiit'iit lur t'lmr dnys in finicciitratcd aciiicdiis suliition nl' lilli- iiiin carliDiiatc. The Nissl l)ciilifs have Im'i'II (lissol veil (iuI, and llic }i!'iiiiii(l slll)- slaiicc alciiir rcinaiiis. (At'tir II<1(1.) TIIK INTEUXAIi M()UIMI()I,()(iV OF XKl'IfoNKS. i:w ton, too, lias a|)i)lii'(l ,v saiiic tost, but doi's not ol)tain any dis- tinct reaction Tor iron. Macallum * liinisclf, liowcvor, aj^pcars to liavo dcnionstratod tlu! presence of iron in the substance. In his a(hlress before the physiolof,ncal section of the Britisli Medical Association, held in Ediid)urgh in July, 1S!)S, he referred to some investiga- tions undertaken by his j)upil Scott, mentioned tliat iron and phosphorus exist in the sul)stance, and stated that the Nissl spindles of the ventral-horn cells resist peptic digestion (as Held had shown), but that they are slowly digested with trypsin. He coiududes accordingly that they are of the nature of a nucleo-i)r()teid. .Macallum has develojied a nu'thod for the his- tological detection of j)hosphorus which seems to be more exact than the procedure of Lilienfeld. Instead of using pyrogallic acid as a reducing agent on tissues previously subjected to treatment with acid solution of ammonium molybdate, Macal- lum employs the hydrochlorate of phenyl-hydrazin, removing the excess with water. The lecithin may be removed from the tissues before applying the test by placing the slide, witli sec- tion attached, into a Soxhlet apparatus and extracting with ether. By this method the portions of the tissue containing phosphorus assume a dark-green color. Held believes that these nucleo-all»umins, although invisible in the fresh protoplasm, are present in it in solution, and that they first take the form of Xissl bodies when the protoplasm is subjected to the action of fixing reagents. In further su])port of this view he fouml that with the ditliTent kinds of fixing reagents and witli varying coJicentration of the same reagent entirely different histological pictures of the tigroid accumula- tions and of the masses lying between them could be obtained. f * Jlaealluni, H. B. Some Points in the Miero-Cliemistry of the Nerve Cells. Brit. JI. J., I.ond. (1H!)8), vol. ii. j,. 7T8. •f For exfun])lp, forty-per-oeiit alcoliol precipitates a part of the tigroid bodies iniicii more finely granular than does ninety-six-]ier-('eiit alcohol, while the part of the granules otherwise thrown down in eoaguliimlike masses is not precipitated at all. so that one sees distinct spaces between the single line granules in the larger Xissl bodies. As XissI has always empha- sized, however, for the study of pathological alterations, it matters little whether the Nissl iiodies are preformed structures existing intra ritinn or are till" result of precipitation. The important point is that under normal conditions by definitely uniform methods perfectly constant microscopic pictures are obtained. Nissl has accordingly introduced the term "nerve- 441 i;{4 THE XEllVOL'S SYSTEM. If tlicso invcstijxiitioiis of Hold are coiifirnicjl — aiul the accunicj' with wliicli tliis work lias Iiccji <'oii(lii('ti'(l, as wi'll as that of liis ])rcvioiis coiitributioiis, loaves hut liltk' room for doubt upon this point — wcMimst admit that his su Hil(liini,''eii : Rektoratsrede, ^Jiinchen, lH!)(i) von KiiplTer himself uses protoplasm to indicate tlie jirimary ukI active part of the cell, anil re- fers to para[)lasm as the secondary or passive part. TIIK INTKUN'AL MOUIMIOI.OOY OF NKrUOXKS. 1:57 (•ells in their liistogi'iiesis, and licliovt's tluit ii " nerve cell " is no more cupable of tiie hi<;iiest fniietions of condiietion l)efore tlio apiieariiiice of the neiifolihriliie tliaii is a muscle cell of the highest fiiiH'tious of eoiilraetioii before its peculiar lii)rillit' have been dilTerentiated. One thing wotihi seem certain, if we have to (h-al in nerve cells with a fibrillary structure at all, the fibrils must be sourve cells. The method of xVpathy does not appear to yield very satisfactory results when api)lied to the nervous system of higher mammals. Bet he, however, has * XX. Wandcrversaininlung der si'uhvcstd. Ncurologeu und Irroiiiirzte in Bndoii-Hadcn am 25. und 26. Mai 1895. Archiv f. Psyeluat. u. Nervenkr., Horl.. Bd. xxvii (1805), S. 05;5. f In a still later article, Nissl, on the ^n-nund o( the preparations of Apalliy and Bethe, accepts a fibrillary structure for the nerve cells in {i:en- cral. I Betlie, A. Ueber die I'riniitivfibrillen in den (langlienzellon vom Mcn- schen und anderen Wirbelthieren. ]Morphol. Arb.. .lena (189H), Bd. viii, 8.95-11(1. /I t ; h- w I > I 138 TIII-; NKK vol's SYSTEM. .1 ^, I 111 : '■- (k'vc'lopt'd 11 int'thotl, the di'tiiils of wliicli iirc not yet published, whicli stains the lihrils lu'iuiti fully, even in the nerve cells of man. The prlncipiil points in the method are as follows : The Nissl bodies are first removed from the .sections by treatment with ammonia, in which they arc soluble. Later, the sections are treated with hydrochloric acid, and afterward with molyb- dic acid followed by toluidin-blue. The tibrils by this method stain of an intense blue color. Ik'the has been able to demonstrate the fibrils in dilTerent parts of the central nervous system in both cells and iibrcs as well as in the peripheral nerve lil>res. In the axones of the j)eripheral nerves the fibrils appear distinctly stained, with deli- cate smooth contour runnin;,' in a somewhat wavy course and nearly i)aranel to (tne another. Sin<,de tibrils can l)e followed foi- a distance of lifty microns and farther. They seem to be imbi'dded in a homoffcneous ground substance. Hethe can find no indication of the honeycomb structure of Hiitsehli. In longitudinal sections no transverse fibrilla3 can be nuide out connecting the longitudinal tibrils, and in cross sections of the axones the librils appear as isolated points in the homogeneous substan(!e. The fibrils are more separated from one another in the axones in the peripheral nerves than in those inside the central nervous system, apparently owing to the presence of relatively larger amounts of the honujgencous substance. The tibrils inside the nerve cells are so distiiu'tly stained that Bethe is much impressed with their independence. He does not think that they are actually a part of the protoplasm since tlicy seem to be so markedly differentiated from the latter. They occur everywhere in the unstainable substance of Xissl. Hethe dilfers from Apathy with regard to the relation of the fibrils to one another inside the nerve cells ; whereas A})athy describes the formation of fine intracellular plexuses and net- works through multiple anastomoses formed by the subdivisions of the tibrils within the cell protoplasm, Hethe is of the opinion that the fibrils do not unite at all inside the cells, and that the close perinuclear plexu.s which often resend)les a network is in reality oidy a fcltwork of isolated fibrils. Thus far, Hethe has studied chiefly the Purkinje cells in the cerebellum, the ])yraiuidal cells in the cerebral cortex, and the cells in the ventral horn and in the dorsal horn of the spinal cord. TIIK IN'TKKNAI- MDlJIMlOLoCi Y OF NKl'UoN'KS. \l\\) Ilia stutcments with rcfjiinl to tlio *). Siiiiiliir networks have lu'cii sccti l»y N'cratti, an a;Hsistant of (iol^'i, in the hirj^'c nerve ccIIh wliieli (i(»l^'i believes j;ive orijjin to the axones of tlie nervus troeh- learis. (iolgi stutoH that he can Hay iiofhiiifi: concerniM^' the si^Miilieanee of the endocolluhir network, hnl he is in- clined to ])t'liove that his fin(linf,'s thus fur arc only ii partial manifestation of finer and more complex structures. He feels sure, however, that this lu'twork has nothing' in common with the clas- sical (leseription of Max Schultze and his school ; that it has no umilogies with tlie pictures discernihle in Nissl ])rcj)a- rations, and that it olfers no correspond- ence with the interesting results of Fi(i. 7H. KiKlocciliiliir net- ApiUliv Concerning the lu'rvc cells of work within i( I'lirkinjc . *, .■I'll of thf rciciiciiiiiii of invertel)rates. S'a '■';;:;;;;•::,..':;;;;;':" n^'i'i^ *" ''"I'^tion t,. his studi..s of iiuMlUiciiiioiiof III., liipid the stainahle part, has also turned his (tolKi iiictliod. lAfl.r . ' , „ , (". o.iiKi, Anil, iiiil. .!(■ attention to the ground mass ot the l.iol., Turin, t. XXX. 1S...S, j,,„toplasm of nerve cells; tlie full results of his research have been pub- lished in an article of nearly one hundred jiages, and beau- tifully illustrated with lithographic jtlates.* He states that in sections fixed with alcohol, pierosulphuric acid, or cliromic acid, it has a distinctly reticular apiiearance. In very thin sections he can make out granules which are extremely fine, staining on tlii' limits of microscojiic ])ercej)til)ility. No tibrilhe could be observed except at the wedge of origin of the axone and in the more cytodistal portions of the dendrites, in which tlie tigroid masses cease to appear. Here he coi;hl make out, stained bright red in erythrosiii, a tine longitudinal striation along with an arrangement of extremely fine granules in rows and i)ressed together, as it were, so as to give the appear- ance of fibrilbe. Held believed at first that he had before him the librils of Max Schultze. On using dilute solutions of * irold. H, Heitrttfjc zur Structur der Nervcnzi'ilon nnd ilwcr Fortsiitze. Zweite Al)han(lliiiij,'. Arc-h. f. Aiiiit. ii. I'liysiul., Anal. Abtli., Lcipz. (1^97), II. iii n. iv, S. i204-2!)4. if) * Kamuii y Cajiil {op. cil.) lias rocuiitly supported vigorously llii' doclriiM! of ii lioiu'ycoiiili stvuclurc for the imstainiiblp sulistancc. f Fisclii'r, A. Zui' Krilik dcr l''i.\irun<;siiR'tlio(l(Mi uiid dor (iranula. Aiiat. An/.., .loiia, i?d. ix (1894), S. (STS-tWO; also Ncuo Hcitrii-ic zur Krilik dcr Fixirun,<,'siiiftliod('ii. Anal. Anz., Jena, Bd. x (18!)4-'9.')), S. TOft-TTT. :{ Oalootti, (i. rdicr die (ii-aiiulatioii in den Zi'lU'ii. Internal. Monut- schr. f. Anat. n. Physiol., Ivip/., 15d. xii (18!^)), S. 440; 4G1. ■ 1, !/:i TIIK INTKHN'AL M()I{IMI()Ii()(!Y OK XKl'lJONKS. n !■."'' (•Iinimi(! iH'id, however, imd of uininoiiiuin hieliroiniitc, lie tliil not ohtiiiii til)rils, Itiit in the thiniioHt HoctioiiH hiiw (tistinet I'oiiMilike stnietiire.s ; espeeiiilly on .stnininjf witli iron-hienia- toxvliii without iiny siihse(|iieiit ditVerciitintioii, he (d»laine»l honeyeonib i)ictiii"es wliieii correspond entirely to tlie pietnres and descriptions of Hiitschli. Ilehl, in opposition to Mux Schultze imd II. Scdiiiltze iinionj^ the older hist<»loj;ists, iind I'Meiii- liiiiif?, Heiuhi, and Doj^iel of the present time, is inelineil to ji(!- (H'pt Miitseiili's view thiit tlie (ihrilhe of the ohler ol>servations correspond to lonj^it iidinal layers of honeyeoinl) cells which lie close over one another ; Held will not ^'ra lit, however, that the nerve cell actually possesses a honeyconilt structure, since he l)elieves that lixino' a^^ents with which it appears exercise u marked vaciiolizinj; iiillueiicc upon liviufjf nerve-cell proto- jilasni.* lie has worked with an extensive seriis of fixing re- ji<;ents, ineludinjj:, in addition to the weak bichromate solu- tions used by Schultze, the lixiiif? fluids which Hiitschli has emjiloyed, and also the niajority of the tliiids now j^enerally ii])plied in the teehiii(pie of modern cytology. The results he has ol)tained lead him to the view that the various dilTer- enees met witli in the (h^scriptioiis of iiivesti<,'ators in dilTerent laboratories are in lar<,'e part due to the fixinii; factor. Nor does Held aeeejit Rosin's view that of the two main sub- stances in nerve cells one is acidophile and the other baso- pliile. Uelyiiifj rather iiiton the recent researches of A. Fischer,! and of the Italian investij^ator (ialeotti,;j; he has come to the conelnsion that the so-called elective stains de- pend more ui)on physical factors than ujion purely cheiiiieal differences. In the first jilace, closely arrani; S ol' NKl i;()Ni;s. l.|.;> consists entirely of iieiiropliisiii, uliicli also extemls in iiMKin;,' the lihrils ot' the ccnti';!! eore. 'I'lie lilirillary appearanee is easy t(» make out in the axones of ey( lostonies and niollnses (Riiwitz). Siihseipienl researelies upon liii^lier forms make it not im- prol)al)K> tliat. a simihir structure hohls in th(>ni. It would seem, however, that, in inedidlated nerve lihres the axoiic lihrils are moi'c evenly distrihuted throughout the whole axone, tlu^ peripheral layer of pure neuroplasm l)einjf ahsent alto^nM her or reduced to a very thin superlicial lilui ( l-'ii,'. SO). 'I'here are mm Kk;. HO. — LiiiiKihiiliiinl mikI Iransvcrsf section of in.Mliilliitrd nerve li'nres I'roni iIm' seiiiiie nerve ol' llie IVou ( osinie ill-id :inil aeiil I'lielisiue ). (Alter Itieder- niann. ) 'The lon;;iln(lMi;il section sliows one node of itiinviei' iiml two of I-iUilerniMnn's sej;Mienl;ilions. The lilirilliiry striicliire of the axone is sliowii in liotli lou^' and eioss section. lujiiiy histol(>u,t,f;iro '" tiiid of Levi.f 'I'he former too, in his stmlies of the nervi' cell under patholo^ with lead iiinl jirsenic — liiuls that the lihrils mav hccome verv distinct inside the nerve eells.t Ileld's description of his liiidiii!j;s in the tixis cylindci's of nerve cells is leiiiithv an.; detailed. With a liirtre series of 1 i n * liiitraro, I']. Sill valoi'e rispelliva ilelle |iai'le erdinalica e della airo- iiialica n(>l citoiijasiiia ilelle eelliile iierviise. IJiv. ili |iatol. iierv., {''irciize, vol. i (IS!l(i). pp. l-II. f Ijevi. (J. Sii aleiiiii' pari ieolarila ill si nitl lira del iiiii 'ei. i celluli! niTvosn. Itiv. ill piclol. iierv., t'lreiize, vol. i (IS!((i). pp. Ill I lit. X Iiiinarii, I'l. Siille allera/.ioiii ileeli eleineiili iiervnsi in't^li .iiVeli'im- ineiiti per afseiiico e ])('r piiiniiio. Uiv.ili palul. iu>rv., Firen/.c, vol. ii (18!)T), pp. JiMM. J 1 i '1 I i: ifM i I il if ll 144 TIIIi: NERVOUS SVSTKM. itit;.-',-. ^' .I'j fixing I'Oiifi^ents, amonir wliicli van (ieliiu'liten'a niixHirc (CO parts alcohol absol., 'M) puits clilorot'orm, and 10 parts acid. acet. glac.) yielded the most constant and satisfactory re- sults, Held conchides that there can be no fibrillary structure of the axis cyliiuler if by the term fibrils one uiulerstands isolated threads running near one another. Instead of these, Held finds always a network- like ap}»earance which in his „, . . ,. T . , 1 thinnest sections is seen to be Fkj. 81. — Axis cylinaor m loiifr iiiid ^v-:i^^-- ^-V-" •••■•/ ••.'A;:: ^**: V \^ . a,".. » -j^.-'^_: '■::', .-. v. .• '•.; > !•■'/, ;'. '• V • . . '.'■ ■ '■7:.'.' ;*•;• '■■■ ' i. *aJh« ■'•. * ■ •" .• •• ' *' ' .* * •* ^ • » •*' *••'■• * • *'•. ' .>* !• V, .'.•;• ..■;...•.-.,'• •,■.,«.",/•■•:••• •" - ...»"' Sheath. Nuclei of celts of sheath. Via. 82.— Axoiie liillock of a siiiiinl (laturlion cell oI'IIumIi,};. ( .Vl'ter Held, .\rcli. f. Anat. n. Physiol., .\nat. Alitli., ISil", Taf. n, Fi^. 4.) fixation with siih- limate-acetone : parallin section l.."> microns tliuk ; slainint; with er.vtlirosin ineth.vleiie-hlue. The Nissl hodies, the neurosoines, the c.vtospoiiKinm and the axospouKinin aic visilile. '{'lie arrangement of the neiirosomes in rows and the lon^titndinal mesh t'ormatioii of the axospoiifiinni is parliciilarl.v dis- tinct. The alteration in the appearance of tlie meshwork where the axone hillock fjoes over into the hody of the cell is distinctly shown. These granules — Held calls them neurosomes — are not, he states, reguliirly distril)uted either in longitudintil or cross sections of tin axone (Fig. SI). The neurosomes appear to Tin-; IXTKRNAI. MORPHOLOGY OF NEURONES. 145 liiivo boon observed before by l?utsclili, Altmaini, aiul others, tlioufj;h l)Ut little iittontiou seetiis to have been paid to tliein. Ill tlie axone hillock the iieurosomes present coiistautly a radially ('onverijiii<:f jiroupiiig (l''ij,^ ^'-i)- 'I'hey sei'in to be extraordinarily numerous in the terminals of many axones, for exaini)le, the mossy and elimbintf iibres of the <'erebellar cortex, in those ending on the ventral horn cells (Fig. >>'■>) and in the terminals of the axones of the i)eripheral olfac- tory neurones. Inasmuch as in the ground substance of the dendrites and cell bodies of the neurones the iieuro- somes are much less nunu'rous, a ready method of distin- guishing the ])rotoplasin of ti-rminal ax(»nes in cytological jireparations from that of other ])ortions of neurones which lie in direct contact (or concrescence) with one another is afforded ua* Montgomery,} in ini able pajjer, has denied the existence of fibrillary structures in nerve cells. lie supports the doctrine according to which hyaloplasm and spongioplasm are the two ])rinei))al constituents of protoplasm. Flemming J emphasizes again that lie has admitted that his fibrils may be i 'inected by obli(jue Iibres running from one to another. He niiantains that in any case the longitudinal fibril- lation is always much more pronounced, and that it can ofti'ii be seen when nothing in the way of a transverse fibrillation is discernible. \'ai'ious attem])ts have l)een made to connect the function of conduction through the })rotoplasm of the nerve cell with one or another of its finer histological constituents. Apathy * es[)ecially is convinced that his "neurofibrils" reiireseiit the essential anatomical basis for conduction, ami he constantly re- fers to these fibrilhv as the conducting element {this Ici/nu/e l\lniinil) in the nervous system. Betlie shares this view. * Held hclii'vos tliat the lilirils of some Investigators — for example, tliose of Dofjiel — are in reality identical with rows of neurosomes. He even hints that some of Flcinmiiiij's filirils n'lu'esciit hands of neurosomes; olhcr filn'ils descriiied \i\ l-'leniminf? are. Held l)eli(>vcs, heams of the eytosponj,'iuni. f Montfjoniery, T. H. Studios on the Elements of the Central Nervous System of the Heteronemertini. .1, Morphol., liosl., vol. xiii (18!)7), pp. 3S 1-444. ^Flemming, W. .Article Zelle in Merkel-Honnet's Ergetjiiisse der Anal, u. Entwiekehingsgeseh.. Md. vi for IMJIG, Wiesbaden (1H!)T). S. '.MM 11. « ()l>. cit. 11 11 /< 1v II U' ( ^ ^*->.. . TIIK INTKHNAL MoKIMlOLOdV (>!•' NKrUONES. 14' It wiis and is still Ticydi^'s* opinion tliiit tlio " liyiiloplasni " of i\n' nerve cell whidi fills up llu' (lu'slu's of tlie spoii^'ioplasm represents the eondm-tini,' suhstanee, a view wliieli, in the main, was supported ])y Naiisen, though the Arctic explorer assumed that the hyaloplasm is arranjjed, hoth in the axis cylijider and in the body of the ni'rve cell, in the form of "primitive tubules." Other invi'stifjators assume that it is the spon<;ioplasin which is active as the conductinj^ a<;i'nt — an o])inion which would accord well with the ideas of MacCallum f with regard to the cojitractility of muscle. The liypothes(^s of Leydig and Nansen have l)een vigorously opp()S(Hl l)y Hiitschli and by IMlueger. Miitschli himself is strongly of the opinion that tiie framework substance of the nerve-eell protoplasm, his Wiiijciit/cril.s/, must be considered to be the histo'ogical substratum of nervous conduction, since it alone extends continuously tiirinigh the axis cylinder, and is accordingly the only structure in a position to underlie the ])heJU)men()n referred to. He brings forward in favor of his view the statement of I'llueger that ni'rve iibres can hi! excited only by means of currents tlirected longitudinally, not by cur- rents directed transversely. Held argues that, in view of the possibility that the so-called foam structure may be an artefact, due to the tixation of the pi'oto})lasm, it is premature to assume that the meshwork ■sei n in fixed specimens is necessarily the conducting suhstani-e. Kven if it does correspond to the structure of living })rotoplastn, it would he diflicult to deny for the delicate transverse con- necting bands the possibility of a function freely granted to tlie longitudinally running c(»arser beams of the meshwork. Held is inclined to look upon the ground substance of the protojdasm, '^s• a //'//»/(", as uceoiinting for the function of the propagation of stimuli, though he does not deny the possibility of the tempo- rary existence of sei^tions of this better or wors;' adapted for tlu^ function de})endent upon alterations in vital chemical constitu- tion. As a matter of fact, /rr i/ I'rcscncL' of ("cntrosonics and Attraction •Spheres in the (laiif^iion Cells of ffi/ix PovKi/iti. with Hemarlv.s upon the Structure of the Cell Body. Princeton Coll. I5ullitin, vol. viii (I80ti), No. 2, pp. :'.S-4I. * llanuiker. .1. 1. The Nervous System of Xciri.t rZ/v/f-s' Sars. A Study in ('oniparalive Neiiroloj;y. Hull, of the Mas. of Coinp. Zool. at Ilarvanl Coll.. vol. xxxii (IHi)M). No. ti, pp. 89-i;.M. II Ijewis. Mar^faret. CeIlt^o^i<)lne and Sphere in Certain of tlu^ Nerve Cells of an Invertebrate. Anat. An/.. .Tena. l?d. xii (1890). S. :291-2!»y. i 1* : i ; J ' ■■ i. I i:.(i TlIK NKlJVOl'S SVSTKM. IK) riiiK'tioiis other tliiiii those eoiieenied in tlie division of the cell; indeed, it niiiy have to do in niiiny instiinees with motor activities of cells indei)endent of thosi' involved in mitosis. Itesides, the existence of centrosome and sphere in niiiiiy cells, which are not dividiiifj and whicdi exhihit no deti- nite phenomena of motility, make it likely that these strne- tiires are of value to the cell in ways other tlian tiiose hitherto su^ tVinii ihr vciiifnl horn nC llic siiiiial conl 111' a ral. cord in ISS-?, publisheil in the Kncyclo])cdie mcdicale. Accord- ing to the Italian ohserver this investment [iresents various a])- })earances; sometimes it is a reticular structure; sometimes it forms a continuous homoufencous layer; sometimes it apjjcars * ("f. Jilso (idliri. ('. Intonio air orij^'ino del (niarto iicrvo ccrt'liralc c ili una (lucslidiii' istn-fisitildf^iua clie a qiit'Slo Mrudiiioiild si colleira. Kt'iidic. d. R. Accad. d. l-iiicci (18!)8), ii. Froiu-h 'riviiisl. in Aicli. ital. di> liiol.. 'I'uriii. t. xix (ISn;!), pp. 454—174. Also. Sur la striirturi' dcs oi'llulfs iiitvcusi's. Aruli. ital. de biol., Turin, t. xxx (IWW). pp. «0-Tl. r m^^' Fl(i. Sf).— rcrici'ltilliir iict\V(i;ks hclicvid liy Held In lie Idinicii l).v llic triiiiiniils 111' MNoiifs. (ii)lni iifi|i;iriiti. 7. and S.I .\'. (VII with nctwmk IVnni iiiiclciis iicrvi ciMJilfaiis vciilialis. Tlic iH'riccllular network siindiinds tlie wiiole cell and a dendrite passiim upward. The lilire n eniicspnnds to one id' the thii-ki'ne(l lilires (if the N, e(ieiih'a' desci-ihed )py li'anion ,v ( 'ajal and II(dd. lieyond llie lliiekened spot lihrils j.'(i to Join llie i;iiieial piTiceliniar network. 1>. I'arl of tlie iielwoi'k ai'onnd a cell in llie nnileiis nervi vestili- nlaiis lateralis (Deitiisi. Held lielieves that the thicUeiiinirs in the nct- wmk may ciirrespond to the a^iireijations of nemusoines which stain in inm- Incniatiixylin preparations. ". '<, c. (/. c, ,/', axones wliich help to t'orni the network. ('. Part of the network around a cell of the nucleus mrvi coidi- learis ventralis: the anastonnises i>\' the coarser suhdivisioiis ol' the lihres ((and /( ind the larger swelliiifis of the threads of the network are dearly visible. t !H i p i:>'2 TIIK N Kit vol's SYSTKM. as ii niosiiic of (Icliciitc scales; not iiifr('(|ii('tifly it presents iiiarkiiij^s wliicli |»rol)al)ly <'<»rres|t()M(l to tlu' imprints of nerve lihres or other fibres inipin^'inj,' on tlie nerve cell. Tiie retien- lar variety seems to he most common; it may invest the wliole of tlie coil body and bo followed ont n|)un the brancliinfj; den- j5«»-r~' Vui A H . S7. Nctwcirksiilioiit )i<'rikiir.vipii :uis('ril)»'S and pictures (Kij;. S(i) pericellular aiul pcridcudritic iictwdrks dcuionstrablc by (ioi^q's luctliod, wliidi he believes are t'oruuMl by auastouutsis of the subdivisious of the Hue axones teruiiiiatiuff there. Ill wiuit relation these stand, if any, to the pericellular investnieiwt of (iol<,d, further work must deterndne. liethe by his method also linds pericellular net- works formini; " stockinj^s," as it were, drawn over the peri- karyon and the dendrites. These are illustrated in Fig. 87. * liUpUMj, H. Sulla si rutturudi'i iiucluo ili'iitiito del (■crvillcllo iiciruomo JlDuitorc Zool.. Firt'ii/i', vol. vi (1H!I.")). f M;u'liiiiilli. ('. Sii iilciini' ptu'licolariiri ddli' (•cllulc iicrvosc 4. X llidd, 11. Mcilraj^i' zur Structur dcr NiTviMizcllcii uiid ilircr Fortsiltzc Dritic Ahhaudlunj,'. Arch. 1'. Anal. u. I'liysiol., Lcipz. (1K!»T). Anat. AMIi., Suppl. lid., S. 27:2-aia. A 11 i IMAGE EVALUATION TEST TARGET (MT-3) ^^ // {./ i< i/.A V. 1.0 I.I 1^ M28 |50 "■■ u 1^ 2.2 lis 20 11:25 i 1.4 1.6 Photographic Sciences Corporation 33 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4503 ^^ ^ V iV N> '^ ■^ ^ >f w. o \ . i CHAPTER XIV. SUMMARY OF <)V \l K NOWLIMXi K II'OX TIIi: IXTKUXAL sTiaxTriU'; of xei'roxks. Coiitlicting vii'ws rc^janlinjj cell orgaiiizatidii in j^ciicral — Siiiiiiiiai-v of tlic oxistinjf state of kiiowledgt' i'(Miceriiiiig the internal !n which he holds as to the nature and strticltire of i)rot()plasiii in general. Until some agfei'inent has been arrived at iunong cytologists regarding the latter, we can scarcely hope for a nnanimity of opinion concerning the former. It is not necessary here to discuss in detail tbc diverse theories bearing upon the . nature of protoplasi>i. A whole series of them — the micellar theory of Xiigeli, the network theory of Frominann, the thread-framework theory of Flcm- ming, the foam or honeycomb theory of Hiitschli, the })lasome theory of Wicsener, the bioblast theory of .Mtmann. its well as many others — have been fully outlined and compared in several places.* The majority of histologists and zoologists can not conceive of the cell is the elementary organism of the body, but postulate the existence of units or elementary oriianisms tniich smaller than cells. f Those who are interested iii developmental * Cf. Ilertwig, (). Die Zelle und die (iewelie. .lenii. isici ; ("arnoy, J. R., and II. Ijehrun. \iH eylodiurese de I'd'uf. \m vrsicule gerniinative el los globules polaires cliez les hatraeicns. Cellule. Lierre and Louvain, t. xii (l'S!)7), pp. IS'.)-'^!!,") ; and especially for a lirief liiit tliorougli critical I'evicw eunsull Waldeyer. W. Die neutM'en Ansicliten iilicrden Hau und das Wesen der Zelle, Deutsche med. Wchnsclir.. licipz. u. Herl. (IS!).')), xxi. 70;i; 727; Tlasm and en(h)plasm there can be made out, in tissues which have been fixe(l, a more or less homogeneous ground substance in whicli are dej)osited larger and smaller masses of a granular nature. The grouml snl)stance corresponds, in tissues fixed witli alcohol and stainecj l)y the methods of Xissl and Held, to the " unstaiiuible sid)- stance " of Nissl, and the nuisses of granules to the "'stiiinable substance " of Xissl and the i)igment. The " stainable substance " of Nissl (the tigroid substance of von Lenhossek) in tissues of healthy animals of tlie same age /I -rTt y I lie l'r. Van Gioson. State Hosji. liull.. I'tira (1S!I7), ii. pp. KW-ISS; SlTilir, A., Letzte Lchenseinheiten uiul ilir X'erhaiul /u einem Iveinipiasiiiii Ijoipzig u. Wieii (1S!(7); Meyer, A., I>ie I'JMsiiiaverhiiiiliiiiijeii uml die Mi'inliraiieii voii Volvox glolial or, aureus uud terlius, luit Uiieksiclil aiif die tierisclieii Zelleii, Bot. Ztfr, Lcipz., I5d. liv (1800), No. 11-12: aii.l von KTilliktr, A.. Die Eiior- ffiden von v. Sachs iin Lielite der Gi'welielelire der 'riii(>re. N'erliaiidl. d, phys.-med. Gesellseli. zu Wiirzli. ii. F.. I'.il. xxxi (lK!)r), S. 1-21. i ir)(i THE NERVOUS SYSTEM. II t iiiul species, killed in ;i prescribed maimer and sul)mitted to the same method ol" tixinir and staiiiiiij^, is toierahly constant in a])pearancc and arrangement in the cell bodies and den- drites of the same groujjs of nerve cells, a fact of extreme im[)ortance for nerve anatomy and pathology. The axones, as well as their hillocks of origin in the l)odies of the nerve cells, appear to be entirely devoid of the " stainable substance " of Jsissl. Whether the stainable substances represent bodies precipi- tated from solution through the action of reagents or bodies pre-existent thougl) invisible, first brought into \'ii'\v through the action of llxing or staining reagi'Uts in the hai'dcncd tissues, in cither case they appear to yield the chemical tests character- istic of the group of nucleo-albumins. Whether the staining reaction characteristic of the staiiud)lc substance depends upon chemical relations or upon purely i)hysical conditions must, for the present, remain und(^ci(lcd. The " unstainable portion " of the cell body — that is, the ground sul)stance — though jtrobably functionally mucdi more important than the " staiiuible," is not so well understood; its nature and structure are still as obscure as those of protoplasm in general. It is here that the so-called fibrils of the variou-: in- vestigators (Flemming, Apathy, Lugaro) occur. In this ground substaiu'e, aside from the Nissl bodies, very fine granules or TH)dul(> formations can be demonstrated whi(di stain with ery- throsin and with acid-futdisinc (Ueld's lu'urosomes), and in cer- tain parts of the neu'-ones these are arranged in rows, thus bringing the nerve cell into agreement with what has been ob- served in animal cells generally. The ground sul)stance is eas- ily vacuolizable, and the erythrosinophile granules apparently represent the luxlal points of the mcshwork which results from the vacuolizaticm, though sometimes they appear to lie in the vacuolar cavities. With suitable methods not only can longi- tudinal markings coniu'cting the I'odal jxiints be made out, ])ut also more di'licatc transverse markings. As to the physiology of the various elementary histological constituents, we can say but little, 'i'he nucleus doubtless presides over the functions of nutrition. In some way or am)ther the grouml substance conducts what we call lu'rve impulses, whether as a whole or by means of tibi'ils, a network, walls of honeycomb spaces, hyalo- plasm, rows of neurosomes, Apathy's conducting primitive TllK INTKUXAL MOUrilOLOdY OF NKL'UOXES. l.:,7 (il)rils, or Kngelniaiin's loii^'itudiiiul rows of iR'urotiifjfnu'ii ;ul noriiium iiiotajfiiu'ii, we do not know.* Should iiitt'rct'lliilar siiltstaiici's otiu'r than thi' lympli and lunxroirlia, of a lll)riUary or more honio.m'uoous nature, sonu'tinie he dcnumstratt'd, it wouhl not he surprising?, hut tiius far the proof for the existence of such suhstaiu-es is wantinj?. We can scarcely hope for a clearer understanding of the structure of nerve cells until our cepluilon) and afler-brain (inyelenceplialon), irradually nnder^o those nietaniorplioses wiiicli nltiniatcly yiehl the ('oin])Iicated brain strnetnre eharacteristie of tlie adult.* The reUitions will *Tlie results of tlie studies of His upon t lie gross Tnorphology of the iiuniau nervous system durinir ilevelopnien>" have been made aecessihle to all tlu'iiutfli his puljlications,an(ies|ieeiallybymeansof an exeellent series of exact wax-moilej reimxluetions. Hased upon these we have been supjjlied for tiie first time, too. with a nomenclature for tlie nervous structures wliieii iiu'cts the (lemands of eml>ryoloi,'y, comparative aiuitoniy. and clinical neurology — a noinenelature the use of which I can not U>o strongly recommend to those who have occasion, in writ in!; nr teaching, to make use of lu'urological terms. Cf- Section Neurologia, in I)ie aiiat:)inische Xomeiielatur, Nomina Ana- tomiea. Vei'zeiehniss der von de atomischen Gesellsehaft auf ihrer ix. Vers, in Hasel angeiiomnieiieii Naiiu'ii, Eingeleitet unil erliiutert von W, /I I \ l; '! ( ! I !'• ino TlIK NKKVOL'S SYSTEM. hv surticioiitly clear if the rciulcr study ciircfully tlu' (liafjriinis (l''i,irs. S!i-!l-.') here iiiscrtcil with tlu'ir iipprnpriatc U'j^'ciids. Fid. Si(. .Median si'ctiim tliroiifili cmljryo liimiun l>raiii at tlic cud of llic (irst niciiilli. i.M'lcrW. His. .Krcii. I'. .Vnat. ii. IMiysinl.. .\iiat. .\l)tli., i^ciiiz., l.SiKJ. i 1. .MvclciiccplialiilL. I.-', rarsddisili.s. II. .Meti'iici'|i]ial'iii. II. :.'. ('(•icImIIiiiii. irr. Istliniiis. HI. :,'. Hracliia (niijiuicliva, Vd. iiu'd. ant. I\'. Mcscncciiiialon. I\'. ;.'. Ciirpora (luadilKcniina. \'. OicnccpliMldn. V. I. I'ars iiianiiiiiilaris liyinitiialaiiii. V. ^. Tlialaniiis. 1. 1. Pais vcntralis, II. 1. I'.nis. n I. I. I'cdiMKiili CI rchri. 1\'. 1. I'cdmiciili ccrcliri. V. 15. Mctalhalanu y. I. I'piliialanuis YI. 1. Pars (iptica liyi>c>tlialanii. \'l. 'rcicnccidialnn. \"l. )l. ( nrpus striatum VI. '.i. Hliincnccplialon VI. 4. Pallium. His. r.cipz.. ISO."). 'IMiis noiiu'iiciatiirc lias been closely followed in tlie jircsent book, except, that I have substituted the worJ.s ventral and dor.sal ! IFIST()(iK\l''/ri(' K'KFiATIONS OF TIIK NKIUON'KS. jr.l Tlic derivatives of the tiirt'c ccrcliriil vcsicli'S an- outlint'd ill the iiccoinpiuiyiiif? table on paije lt>;{. Nor sliall I periiiit iiiys'-lf to (li';•., imns curve : T. «., cliiasiiiii niiticiMii ; <'.sl., (•(irpiis stiiiitiiiii ; /■,'., iiiniiciitia iiitciiicdunciitai'is nl' tlic isllinms; /•'.(•//., tis- sura cliiiriiiidca ; /•'. ('.. I'ossi iiiliT|n'(luii('iilai'i.s ; ///)., ttuniciilal iinijcctinii ; //r/(,, (1 rclicllar litiiiisiilurc ; /.. istlini'is : /,. ^, lamina tiiiiiiiialis ; .1/.. ciir- piis iiiaimnillai'c ; .l/A., I'nol' nt iiiiil-lnaiii : I', s.. liyiiiitlialaiMiis i pars sulilliu- laiiiica ' : r. I!., aiilrriur iiitactmy lulic ; h. It., puslciinr ulCaclnry Iriiiii diiriiiK the tliird iiiontli. (AClcr His. Arch. f. Aiiiit. n. I'li.vsii.l.. Anal. Alitii.. IWi:}. S. 175, Kij;. 2.1 Tlic Icllcriiit' is Ik lie intci'|irctctl in llic siinc wa.v as tor Fis.^NK. 1 I ■(//(■ Kiiiirii.i Sulcus cinguli (lulls iiKiiyinalis). Sulcus cinguli (/in i:i siiJifrontiilis). f'-Ki. 02. Median section tlironfjli adult Ininian brain. lAt'ti'r His. Arcli. I'. Anat. u. IMiysiol., Anat. Al)tii., IMIW, S. 17(>. Kifi. 3. i Lfttoring .same as in Fin. Wt. (, Vide siipni.) a o at ® M ^ *-* :: "3 '5 B H ST 4« a. w s w s w .a o u = c- c c ;ji it %> as sS C '51 ^ i •- ^ c r 2 % _ K u u — ■/; ■r. 3 "5 "3 3 L- 'u ~" ^ ™ 2 E X k, x: F! ~ 'fl ■a (. P-t 6 c 3 13 2 ■A S3 15 'a, &3 cZ — c s 9; a- &, C C-^' •^ aj ■»— ' 1— 1 ^ ^ ^ ^ "^ c« n ■♦ « n « = — ^ »-» ^ *^ 1^ r^ 1^ > > t- <>!• ISOA ,1I.)IS0.\ |1!.I(^ ^1 )isaA \\ui\MM joiaaviv inj(1<)joa jouo4so,i -OJOO '»n'P!i\ ■:(-( I, 'i "nl' i»;4 TIIK NKUVOL'S SYSTKM. of tli»Ml('vi'li)|)mciit of tlic cmld'yo, iiilliH'iii-cs of (litrcrciit kinds, siii'li !is viiriiit ions of li'iiipcnit urc, ol" the i»xyj,'<'ii supply, ami of other coiKlitioiis of ciiviroiiiiH'Mt, or truiiiiiii it'ii(liii<,' to injury of portions of tlif v^iii or of the sof^iiicntution cells, eiin j^ivc rise to those imfortiiiuite ('iirieatures of human l)einj,'s which we coiii- nionlv ilesi;,'nate as monstrosities, iind foi- the ori<;in of wliicli experimental leratolo^a has (lurincli-< (slfilii;;. I'irp'lniissc dcr all- jji'iii. palliol. Morplml. ii. I'liysiul. Wicsliailfii (IHJI.'i), S. ."iJl. f The principal inihlicaliinis nf \V. His which arc inlcn'sliii;,' in lliis cdii- ncclioii arc (I) Analuniic nicnschlichcr {•liiiliryni en. lii'i|)Z. ("i) I'dicr die Arifiin;,'!' ih's iicriphcrischcii Nci'vcnsvslciiio. Arch. f. .\iiiil. ii. i'hysjol., .\iial. .\htli., l-cipz. (IH71)), S. 4rM-4H2. (!{) Ziir Gcsciiichtf dcs inciisihlichcii iviickciiiiiai'kcs unit ) |)i.. N.-u- niblastcii mid dcrcn {•'.ntslchmi;; iin (!inl>ryoiiHlfn Mark. /Iiiil.. Md. xv, No. 4. I.cipz. (1M8!)|, S. :!1:{-;!T2. (0) Die Foriiicntwickclmii,' dcs nicnscli- lichcii X'ordi'rhinis voin Kiidi' (les crstcn liis zmii l)cj;imi (h's drittcn Moiials. l/iii/.. {{(1. XV. i.eipz. (1H81»). S. (i7;i-r;«i. (7) Die KMlwickeluiif,' dcs ineii.sch- lichcii IJautcidiirns vein Kiidc des crsti'ii l)is zmii |{cf,'iiin ilcs dritliMi ;\Io- iiats. I. V('rh'iiij;crti's .Mark. ////(/.. i?d. xvii, i,eipz. ( IMiH), S. 1-74. (H) Znr allgciiii^iiieii Morpliolof;ic des (ichinis. .Vrch. f. .\iial. u. Physiol., .\iial. Al)lli., Leipz. (lH!r,>). S. :i4(h-:5S;?. (») t'elxT das trontale Kiide des Ochirii- rohrcH. .\rch. f. Aiiat. ii. I'hysiol., Anal. Al.lh.. Leipz. (IH'Ki), S. 1.")7-I71. (10) Vorsddiige ziir Hinllieilung: des (iehinis. /hi, I., S. 172-17!». (11) Ueber iiieclianische (Jrmidvorgiingi' lierisclitT Fornioiiliildmij;. ,\rch. f. Anal. ii. Physiol., .\iiat. Ai)lh.. Lcipz. (lHi>4), .S. \-H{). {V2) fcLer die Vorstiil'en der (iohini mid der K'opfbildiiiig bei Wirbellhiercii. lliii/.. lHi)4. S. ;5i:{-:i;{«». Korllie rojiorls of two iiit crest in^; addresses i.pon some of tlicfjeiieral residts of His's work the reader is referred to ,1) His, \V., Ilistoji;enese tniil Zusain- nieiiliaii},' der Nerveiielemenle. Vorldiaiidl. d. x. iiiteriiat. nied. Con};. l?erl., 4-!». .\n^., iHilO. M. ii, S. 0;5. l?erl.. lSi)l ; ami (12) His. W., I'eber den Auf- l)au unseres Nervtinsystenis. licrl. klin. Wchnsehr. ( 1 SO!]), S. 1)57 mid !)!(0. An excellent critical review in FInglish of all the literature uiion the devel- opment, of the liuman nervous system in its early stajres is to be found in C. S. Minot's Mmiian Kmbryology, pp. r)9;{-743, and in the article by the same author entitled Die friihen Stadien und die Ili.stogenese des Nerven- systems, in Merkel-Honnet's Krjfebnisse der .Vnatoinie und Pintwit^kelmifjr.s- geschichle. Hd. vi (for 189(5). Wiesbaden (IHi>7), S. 087. The subject, is also II and leet which, ai layer of eetohlasi which jj skin aiM — is mad layer of i lial eelh side (V\'fi correspoi ends of 1 1 represent and, afte iniu'r an faee of t its ori^rii the epith iiiit form Fiit. Aniiiiiu iIk' I'liilliilinl icIK w \\w\n- niiinil (.'rniiiiiMl iill willi I'Iriir |irii|ii|il;isiii is \ i>i)iU'. ( Al'lii- His. ) iiieiit of the ])roto|)lasm in the individual cells (Kif,^ !»4). 'I'he nuclei are rarely, however, situ- ated at the ends of the cell, so that very soon tlu' medullary plate, as seen on transverse se(v tion, can he divided in- to three more or less I.-,.,, .|...-S...ti..n lln„u^'h n..nr:,! tul,.. ^^l>i..h is 'I'^tinct ZOIies— a U.id- iMtiiiiiiiiij; if- fcr, of Munich, may also Ix- referred to. ■'it I .!!! /{ I 1 ^(J HI M i I i 1 1 li .' i I i \/ ict; TIIK NKHVOUS SYSTKM. l)liii;f Viiciiok's soon appciir. In tlic distal ends of the ct'lKs (tluit is, the t'lids (lirt'cti'ii toward the outside of the Ixtdy in tile medullary plate, or those directed later toward the inside of the inedullarv tui)e) tiu' cell bodies tend to collapse so as to form a series of striated })illars with siiaces between the indi- vidual cells. The free ends of the cells retain their orif,nnal breadth, and with those of neif,dii)orin,L,' ci'lls form a thin lijuitiiifj; membrane. The proximal ends of the cells, in- stt'a/)). For a time the boundaries between the individual cells at the proximal ends are easily disceriiil)le,* but very soon, throuii;!! further developmi'iit and extension, the cell boundaries dis- appear, and we liuve the appear- ance of a spongy network or of a Via. 9.1.— Section tlii<.u«;li wall oi' ,.|,)h -ly felted thicket, the neuro- iiciiral till)!' al a later stai;e. . ,. 1 1 • ni i Dimieiiiiaiioii cif 111.' two ends sp«)n^num ot 11 IS. Whether we ' ^"'•'' lijjve to do in the thread work with an actual closed network seems as yet not (piite certain. Kanion y (ajal, fnmi the study of silver preparations, denies this, aiul also (lih])utes the independence of the cell territories which His maintains for the nctii-osponre complex with further deveii)])ment. The feltwork, at lirst extremely close, shows later wider meshes, the whole s])onr oC the epithelial cells Mis.) *'i'lie epitlieliiil cells at tills stiige of ililTerent ijilioii are .-pnkeii of liy His as spoii)j;i()blasls. ' i "^ 1 IIIST()(}KNKTI(" UKLATIONS OF TlIK NKL'HONKS. n;7 ncrvo fibres. Indeed, the mnrfxinal veil persists tlirniifjchout life iiiid appears to correspond in the adiUt to a part of tiie epeiidynial framework of tiie white matter of the whole of the central nervons system.* Very early in the history of the mednllary plate there are to he made ont in the intercellnlar spaces of the l)order zone, wiiieh <'orresi)oi\ds to tiie distal ends of the epitiielial cells, elements whi(di have an entirely ditferent appearance from those just described. These elements are desiffiiated by His as germinal cells {Krinizcllni). Tliey are, as a rule, at first splierical in shape, jiossess characteristic clear protoplasmic bodies, and their nuclei in well-fixed preparations are usually seen in the process of rapid division i)y karyokinesis ( Kig. !»(!). The exact relations of these cells to the epitiielial cells before lieseribed and to tlie other cells of the ectoblast still form the suliject of some dispute. Tlie idea that the Kfiinzi'llcii are fundamen- tally ditTerent from the epithelial cells has been vi<,'orously op- posed by Kolliker,t S(diaper,J. and N'i^nal.** The wiiole mat- ter has lieeii very recently subjected to a critical revit'w liy Scliaper.|| It is ur|iitlR>Iial cells into a rraiiu'WDrk jit'iii'trahMl hy s[)ai'('s ami boiinilt'd liy liiiiitmj,' iiii'inl>raiics is not |ii'culiar to the iiu'iliillary plate. N'im'v similar foi-ms arc to la . with iii otlitT t'cloblastic ilcrivatives — for cxatiipli', Ilic rctiiia, Ilic oar. tlic olfactory [ilatf, and llic portions of Hit' fcloldast adjacent to tlic nenral j^roovc wliicli <'orrcs|ion(l, in part at least, to the building [ihux's of the cell- (f the sensory ganglia. + OiK rif. :(Schaper. A. Znr IVincrcn .\natornie des Klciniiirns tier 'relooslicr. .\nat. Anz., .lena, IM. viii, ISlKi, S. 705-720. — Die intirplioltjgische nntl hisli>- itigischc l']ntwii;Uelniig ties Kieiidn'ms tier Telcosl icr. I/iii/., IJd. ixllHli;!- ■!»4). S. 4S!»-r)01 ; also. Morpht>!. .lalirb.. l.cipz., lid. xxi (ISU-l), S. (;'J.-)-70S. * V'ignal. \V. Keelierehcs sur le tli'vcloppcincnt des t'lt'nicnls ties couches cortieales tin ccrvean et tin cervclet chey. I'lioinnie ct les inaniinifi'res. Arch, tie jihysiol. nt)rin. et path.. Par. (ISSS). 4. s.. t. ii. pp. 2',>H-'jr)4 et ;511-:i;{S.— Kecherches sur le tit' eloppoinent ties t'lt'nicnts ties conches cortieales du ccrveaii et du cervelet ehez riioniine et les inainniifi'res. ftcole prat. <1. halites t''tnde.s. Lab. il'liistol. dn Coll. tie France. 'Pniv.. i'ar.. ISSM. t. xii. pp. 54-8'.^. — Rechcrclies snr le th'velt.ppeineiil tie la substance corticale tin cerveau et du cervelet. f/iid.. pp. H:i-I !'.». 1 Scliaper, A. Die fri'ihesttMi DilTereiizirnngsvorgiinge ini Centralnerven- .systcm; kritisehe Stiitlic nntl Versiich einer (lesehichle tier Kntwiekeliini,' nerv."si>r Snhstaiiz. Arch. f. Kiit wcklngsniechn. d. Organ.. Leipz., I$il. v , — I'licildinicniKnii)!! liy A. (i. Ilni'ii IVuiii n spi riiiicii nl' li. (i. Ihiiiisipn's tliriiii^'li the niiniil lull'' of ainlily.stdiiia. Scvcnil cells undcfyiiiiif; (livision l>,v kiiryiikiiicsis ciiii tic seen in llie inner ziine. A liirfte niinilier oreiiitlielial nilrlei are visilile. '{"lie oilier /one ol' the wall of llie lube, which is free from nuclei anil somewhat iiidislinclly shown, corres|ioiiK TIIK NKIWONKS. liii of tlif jn'o- ccss, forming' a fcchly striated ])r()toj)Iasiiii(' coiii' on one side of the nucleus from wliidi the j)rocess ai>})ears to take its orifjin, Tiiese pear-sliajx-d cells, the derivatives of the Kviiii/vllni, are termed by His ni'iirohltists. The nucleus of the cell body of the neuroblast corresponds to that of a future lu'rve cell, and the 'sin<,de ])rocess represents the developincome again surrounded by its meshes. Dohrii be- lieves that in the region of the nervus oculomotorius there may be a peiiiia- nent exit for motor cells. lie brings these cells into connection with the oculornotorius ganglion of Schwali)e. t His, W. Zur (Jeschichtedes ineiischlichen IJiickenmarkes iiiid der Ner- venwurzolii. Abhandl. d. math.-phys. CI. d. k. siichs. Oesellscli. d. Wis- sensc.h., Leipz.. Hd. xiii (l«8fl). S. 4T0-.")l:!. 170 wm inSTOGEN'KTK' UELATIOXS OK THE XEURONES. 171 forniatidii of tlu' iiuuitk' layer of iuMirol)last;^ tlio colls in tlio dorsal half li'ud to wantlor toward tin- ventral iialf and their processes are nearly all directed ven- t rally, the neuroblasts underjjoin^, as it were, a partial turning so as to he- coine ]»arallel to the surface of the niar otin^r side. !(. I'^roin fKaTfpov nfpos, eticli side. i: Jii 17l> TIIK NKUVOl^S SVSTKM. into the vent ml jitul lutcral funiculi of the white miittcr. Of the liittcr, ii liirj,'!' bundle known as the fiiseiculus eerebellos])!- nalis (direet cerehcllar trurt) receives its axones from the ^roup of cells situated in the nucleus dorsalis (Clarke, Stillinf^).* ("oiuparatively few of the neur(>l)lasts send their processes into the rejifion of the dorsal funiculi, these, as well as the re<,non of the pyniniidal tracts, hein^f occupied in the adult almost en- tirely hy nerve fibres which may, in a certain sense, be looked upon as extrinsic to the spinal cord, sine* their axoiu's in their oiifi'in are entirely independent of nerve cells lyinj:; in it.f A very marked example of the wandering capacity of neuro- blasts, and one to which His has frequently taken occasion to re- KiKiiityiiia Spunyiubltist (•'iriiihtdl cell - Medullary tube Suiixritntia ijrhea. — Suhnlciiitia lllbtl. - Deiidiitex. Aj:(M». Fij,'. ;5().H. ) fer, is met with in the development of the medulla oblongata. In its early staf>;es ( Fi • <■ *.d-*-_ . ^5; cy,^ ^n Fk;. 100. — Transverse scctiiiii through tlie «p]H'r tlior.icic sjiiiial cord oftlie liiiiiian einhryo. (.\fter W. Ills. .\l)liaiiill. (I. matli.-pli.vs. CI. (I. k. siielis. (iesellscli. <1. Wisseiiscli.. I.eipz.. 15(1. xiii. IM.sii, No. ti, Kij;, 2. I n. M.. external niantUi layer: ,1. .vyi. n., arleria spinalis ventralis; .1. s/i. ji.. arteria si)inalis dorsalis; ///>., Hodenplatte ; T./', cylinder I'urriiw : />./(., I)e<'kpla1le ; /''.(/., torniatio areiiala : /. .1/., internal mantle layer; ./. />., internal plate; M.l.m., nieni- brana liniitans nienin;;ea ; m. M'.. inotur ventral rout: ». />'., oval bundle of diir.sal I'nnieulns ( /(o^ l''leelisif,''s oval Itundle); li- )'■. niarjjinal furrow; ■•>■. W., sensory dorsal root; S.h.. eorini laterale. spouf^ioblasts, closely to tlitit which I have described as char- ■Krteristic of the spintil cord in its early stages. In the ventral |)l!ito, in a series of sections, c^an be nuuie out (]uite etirly tlie "(roups of neurol)lasts corres])onding to the motor luudei of the medidlii (Nucl. N. hyi)ogl<)ssi, Nucl. N. aocessorii, Nucl. N. vagi, and Nucl. N. glosso-pharyngei), and at this period these nuclei, as well tis the buiulle of fibres known as the tra. Kiir. Ht'. The iixonc piisscs llironf;li llic ventral coniniis.siirc into the snli^tiintiji Krisca of the oji- liositc sidf. Fio. 102. — Tninsvcrso section tlimuKli the medulla of the linmaii eiiihryo. T. s., tr.ictus solitariiis ; A', iiervtis vatjiis ; Xfl, iiervns liypoKlossiis. ( After His. ) the spinal cord), are situated close to the outer surface of tlie medulla* v tube. As is well known, in the adult the motor nu- IIIS'l()(iKNHTIC UKLATIONS OK TIIK NKlUoNHS. «•> cli'i in the mcdullii aiitl the tractus solitarius arc far rciiiovcd from tlu' ventral surface; imU'cd, t licy arc situated close be- neath tlie floor of the fourth ventrieh- (central caiud), hein;; st'jiaratcd from the surface hy nearly the whole thickness of the ventral wall of the medulla, iiududin;,' the pyramids, the olivary bodies, and the formatio reticularis. The explanation of this is easy when the histo wiill cf "" ""' '/'I' (III' ini'diillM nC a liiiiiinti iiiiliryip. (ACirr lli^. ) middle HlU!. Niiiriililii^tsiirisliiiwii wiiiidriiiiL' iVciiii III! rlidiii- , . , lioiiiiil li|> inwiiril ihr iiiidilli' liiii'. Tlir iiiicliiis tor iiuch'i anil tractus nr^n,.. i>.v|m,k1..ssm1 >u.rv,. is iMi.iKi.i.ri...i inihr ^solitarius, while re- taining the same re- lations to the central canal, now oi^cupy in transverse section an entirely dilTcreiit ]»osition as regards the ventral surface of the medullary tube. Instead of lying superlicially they are buried in t\w depth by the crowds of neuroblasts which have wandered in from the lateral regions. These neuroblasts ar- range themselves so as to form the inferior ol- ivary nucleus and the medml and lateral ac- cessory olivary nuclei (Fig. ioo), and last of all the buryiiiLj is made still dec])er by the nyh pearance of the pyni- niids, great bundles of fibres, the last to be nu'duUatcd in the me- dulla, which represent the processes of neuro- blasts situated high up in the pallium of the fore-brain (telencephalon), which have grown down through the inter-brain (dience])hulon), and mid- brain (mesencephalon), to the medulla to end at different Kid. 105. — Scheme of one half of tlie emltryonii! iiKMliilla at a later stajje. Tlie tir.iy masses cor- resiiDiidinj; to tlie olivary bodies have het^n formed, and the imcleiis of the hyjiofilossiil nerve and Ihe traetiis solitariiis are far re- moved from the ventral siirfaee. (After llis. ) T[IST()(iKNKTI(' IIKI.ATION'S OF TIIH NKUIIONKS. 177 Icvi'ls ill the spinal conl. Tliiis the lamcllutioii of the iikmIuIIu ill late cmld'yonic stufjcs aii\ the sue- /I SrFld I'Ki. 1(1(1. — 'rraiisvi'i'sc section tlinxii;!) "iic Imlf of tlic ninliil i1)liiii<'at:i III' a hii iiiMii I'liilirvo at llii'i'i^jitli Miciiilh. I'lliillati (), iilivc willi acci'ssorv cilivaiv linilii .M'tcr Kiillikcr. ) /'. pyramid iidI yet (l(\ tilmi' rcrcl iilivaics; /V, ri>i|nis rcsliluriiif ; /.V, .V, N. ulcpssiiiiliaryii^clis and N. va^Ks ; A", iiiiflciis of li rnilnaliiiii nl' siiisory porliim nl' N. vaKiis; /•'■<, tracliis suli- lariiis; I', ti'a<'tiis spinalis N. liitri'iiiini ; A'//, N. liypuKlussiis. Its niicU'iis iit'nri^'in is snn near tlic tlimr of tlif I'miilli vrntcii-lc, tar rcinovid I'loni llu! ventral siirl'a<'e; /•'///., I'ascieiiliis Icinuiliidinalis ]ne(....,is; >"•', siratniii inter- olivare K imiisci. cessivi' ;i(l(liti(»ii of (1) the motor miclia ; (2) tlu' formatio ivtit^- iiliiris ; (:j) tlu' oliviiry nmsscs ; (4) the pyramids. As tlioy lie, so tlu'y have dcvi'lopcd. Tlicir position is, as it were, tli^ k(^y to their (levelo])inental liistory. 11 17« TIIK NKUVOL'fS SV.STKM. I i i i * Mall. F. P. llislofjeiicsis of the Kcliim in AmblysloiiMi and Ni-i'tiiriis J. Mdi-phol.. Bast., vol. viii (1H!);J), pj). 41.")-4:52. I ill /I CIIAITKU WH. Tin; DKVK.I.OI'MKNT OK Till", I'KKI I'll KH A I- SKNSOItY NKl'HONKS AM) Ol' TIIK HY.MI'ATIIKTIC NKl UOXKS, Origin of scnsf " )i;aiii,'liii. |)ori|ili('riil sensory norvn fibres, dorsal roots o( spinal iicrvi ' and dorsal while fwniiMili of the spinal cord — 'I'lii' devel- opment of liic rfjans of special sense — The ear — The eye — 'i'he nose — Wanderinjrs of neurol)lasts in the fonnation of the syinpalhetic nervons system. WilKUKAS the ()ri;j;iii (»f tlu' motor (il)f('s of tlie pcriidicral nerves iiiid the intrinsic intramedtilhiry fibres is to be soii^Mit in tlie neuroblasts of the medulhiry tube, these do not fjive rise to tlie jjenei'iil periplierul sensory nerve til)res iind the nerve fibres of tlie oi'jfuns of special sense, nor to the fibres and cells of the sympathetic nervous system. How, then, is the orij^in of these to be explained ? Concerning this there has 1)een some dispute, but the skein is beinj? f^radually disentan<,ded. From a {?iven pe- riod of development on, one can make out near the medullary tube on ea(di side jfroiips of cells which re])resent the bc<;innin<:s of the sensory pinj^lia of the dorsal roots of the spiiuil nerves, so that the cell bodies of till the sensory neurones of the first order are situated'outside the neural tube — that is, outside the spinal cord and brain (P'ifj. I OS).* The studies of His, Marshall, Hal- four, Heard, von Lenhossck, and others have taujjht us wheiue these cells are derived. All arc ajjreed that they come from the ectoblast at the junction of the edges of the medullary plate with the adjoiniiiff ectoblast (Fi}i:. 10!»), althoufjh there are a number of researches which make it jirobable that a certain number of the cells do not wander off until the medullary tube * That in development I lie system of the sensory pin;;lia can pfrow en- tirely independently of the presence of the mi-dullary tube, or, perhaps more safely expressed, that the sensory paiifrlia may be present in the absence of a sjjinal cord, is well shown bi- the case described by von lieonova, O. Ein Fall von Anenc(>phalie combin.'rt mit totaler Amyelie. Nenrol. Centralbl., Leii)z., M. xii (\H9ti). S. 218; 263. 170 I i ■I a i§m i ; , I8i» TIIK Ni:i{ vol's SYSTKM. liiis hfcii piiiflicd otV t'roiii the t'ctodenii. In the front |)iirt of tlic head, correspoiidijif^ to the sensory refjioii of tlio trif^einiiius iiiid especi.illy to the iieoustie-fucialis area, tliere exist in Ww. l'"l(i. KIS. — IJcciiiist ruction of iillliiiiii ciiil^-yoal ciiil ol' I'ourlli wci'k, sliowinj; dc- vcliipnu'iil of sensory .L;aii},'li;i. ( Al'irr Mall.) I', Oasscriaii j;anf;li(iii ; .V, \ajius ,naii.Li;liini : 1, lirsl cervical ^'aiiiilioii ; S, last cervical KaiiKlioii ; 1:.', last llioiacic 1,'aiiKlioii. Tin- |ilireiiic iicivc is seen arising IVoiii llii' Idiiilli cervi cal iieive. ectoiU'riii, at points eorrespoiidiiiy; to this jiinctioii, delinite ridry<>. (.M'ter M. von Lenlinssck. i the primary dorsal funiculi, in the nu'duUa, the atudogous trac- tus solitarius, the radi.x desceiulens m-rvi vestibuli, and the tractns spinalis nervi trigemini. The relations of tiie dorsal roots to the spinal cord are well shown, as are those of some of u ' n : 1 i: t • 182 TllH NERVOUS SYSTEM. the cells of the veiitnil horns, in the aecompaiiyiiifj fi<;^iire, copied from van (iehuchten, which represents the rani (Fiinal Kan;;li(pn eells id' llie liisl and seednd type ; /(, trunk pnieesses of eells of tlie lirst type whiidi divide tn lorm the axones 1)1' the peiiiilieral and eentnil tilu'es ; ». axones ol' cells ol' the seeond type whit li I'ud as a perieellular I'eltwork alxiut (lie eells id' I lie lirst typ<' ; .V, syinpathelic (Hires wliieli end as a eireumeellular plexus al>oUt the ecdls ol' (he seeond tyjie. cells (Fig. 11'^). The s])inal ganglion cells of Type II are, he thinks, in turn surrounded by nerve endings from the sym- pathetic, a finding which, if confirmed and taken in connection ji- ll / J,? ? I \f ISO TIIK NEIIVOUS SYS'I'KM. with the ()l)S(>rviiti<)Ms of Klirlicli, and ('specially witli tliosc of Riiinon y Cajal, is of cxtri'iiic si<;iiilicaiicc in ilt'aliii^' witii tli(! functions of tlio spinul <(iinf^lia and the relations of the spinal and synipatlietic systems to one another. 1 have re[)roduced in '''i- ll'l Doj^iel's scdieniatic representation of his conception of relations inside the spinal f^ani^lia. ould take too lon<; to describe in detail tiie mode of development of tlie orj^ans of speciul sense. It is interestinj; to find that the develo))ment in them conforms very closely to that »)iet with in the sensory nerves in f^eneral. .VU tiie |)cri))li- eral neurones in the organs of sjjecial sense, as in the si)inal C'eiltrtil }tuli yrrriis fiaidlis (hniijlion rentibitlare (ianylioti i/fnicidi (liDii/lio)! siiiralp I)}icliis .•l)'l)lil^in^Hl(ll■i^ ItoHtiiior. Diwtii.i .leiiiirirculiiim Utrifiiliis Haccnliin. ■Duct)ii cochlcaris. !'"i(i. 117. Left jiiiditoiy Vfsiclc with the aciistico-facial (•oiiiiiltx ota liiiiuaii >'in- lu'vii at tlif lil'tli week. After His. .Iiiiiior. I'roiii Kolliiiaim's tcxt-liciiik, .S. o Jti, Kifj. :53;5. 1 ganglia, arise from cells of the ectohlast and pass through the neuroblastic stage, the axis-cylinder processes of the neuro- blasts growing into the central organs to terminate in them in free endings. In the ear, for exiimple, the ganglia connected with the cochlear and vestibular nerves contain cells whose two })rocesses grow away from the ganglia, the one toward th(^ periphery (to the cochlea or to the vestibule), the other toward the centre to the nerve tube at the juncticm of the medulla and pons (Fig. 117). These ganglia are in every way analogous to dorsiil-root ganglia, their only peculiarities consisting in (1) the short distance which the peripheral process hits to go before terminating; {'i) the maintenance throughout life of the bi- polar condition. Dim Kit,,- ilerm ... Mrmi- ilerm i ('ii))in>i \ vitii'iim ilcnn) 1 ('iinii-a - i Ri'fiita Sclrra utid <'hi)rioidea \a niSTOC.KNHTIC UKIiATIONS OF TilK NErifONES. [sT t In tlic i-yc, too, all the norvi' I'li'iiioiits of tin- n-tiiiii arc of ncuroblustic orij;iii, and tlic axoiu's of tlu- ('('lis of the ^iiiijjflioii- (•('11 layer, <,'ro\viii<,f Imckward, pass by wiiy oi' tlu- oi)tU! iicivo 7'(7< »/irli hplitlialiiii(' vesicle slupwin;; stalk iiiiil jiiouve in sl;ilk finm a liiiiiiiii eiiiiiryo of tile I'imrtli Week seen iViini lielow. Al'lei.l. Knliinann. I.elir- laicll (ler KntwickellinKS^'eseliirlite (les Menseiien. .leiia, IHits, Kij;. :U(>, S. i»Hl, I Tile aiteria centralis retinie lias lieen ilrawn in Iniin lindin^is in a liUliuin eniliryn at the sixtii week. r J' I A Kilii- lierm Mfno- ...M..(. ilenn I 'iiriiu>i vitii'um ( .U.SD- itfvm) Cornea Retina ■■ Striituni jtiijmenti SileriKtnd Chorioidea l''l(i. 11!). neveli)))!!!}; eye cif Imnian eiiiliryo 1(1. 'i mm. loiij;. i After .1. KdII- niann, Lelulmcli der KntwickeliinKSficscliiciite ilcs Mensclieii, Jena, ISi»s, s. run, Via. :u;5. i and of tlie optic tracts into the mid-brain and inter-brain. The eye differs somewhat in ori,l' I lii' head of ii Itiiitiiui cin- liryo to sliow tli<' Krowiiifi point in the nervous system, and tlie direction of tile f;ro\vtii of the (ibre. }f. niednllary <'anal : /•,'. eye; (), ear; A', nose; (\ ceplialopod eye ; L. sensory cells from tlu' skin of lundn'icns. (After Mall.) forms {(■/. researches of von Lenhossek on the central nervous system of lumbricus, and the investigations of Retzius upon invertebrtite forms). Tn the olftictory mucous membrane the early stages of the neuroblasts are present among the epithelial cells, just its in the ectobliistic ridges from which the spinal ganglion cells arise. But instetid of these young cells wander- ing out from the epitheliiil phite, as appears to be the case with the cells of the spimil giinglia, in the nose they remain * Cf. Mall, P. P. Op. cit. IlIS'nxJKNKTlC KKIiiil)raii(> itscH", tlio axoiK's, which, by the way, iifV(U' Ijucoiiic nu'dulhitt'd, ^rowiiijj upward and backward throujjh the crilirit'orui phdci to cuter the olfactory bulb, where they teriniuute iu free eud-arboriza- jsp.c pan umc / mmM^^^^ I . 'ijt m t ■ ..-n Ui l''i(i. V2\. — Tniiisvci-si' section tlmnijili tlic aiitcriov part of tlic tniiik nl' nii I'ln- lirvK itf Scylliiiiii. (ACtcr Haltniir. ) sp. (-..spinal rord ; sp. ;/., •taunlioii nf ilursal mot ; nr, vciitr.il rout ; ihi. (lorsal, f:)). ii., ventral liniueli of spinal nerve; nip. jiart of nnisele plate already eonverteil iiUo iniisele ; nip. I., pari of inusele i)late extendinj; into tlieliml); »/., nervns lalenilis ; «», aorta ; rli. notoi'liord ; si/, ij.. syniiiallietie !;anf;lion ; rn. i'., cardinal vein ; «/, scfinietital duct; .s7, sefiincnial tnhe ; atln'tii' naiifilion ci-lls arc visible inside the nerve trnnk near ils cdfje. elements which wander out from the spinal ganglia into the regicms subsequently occupied by the sympathetic chain. These wandering cells traveling in the paths of least resistance I'll.. \Zi. einliry( liniKsf,'! nerves litrnre. has caref toxylin a I .\uerbach sels, tiie familiar w all of the to thousai origin in berg have ganglia Ix the first ti of the ner * His, W schr. (1. Jlfd. von Prill lara iniierc .Med. iiervensysteii Oesellscli.d. \ ctTinn^' tlie i V. Lcyden, Ki sdir.. licijiz.. IIISTOOKNKTIC HKIiATIOXS OF TIIK NKlUoNKS. l<»l tend to (((licet in f:r(>u|>s, the synipiitlictic fraii^xlia ; in iiddi- tioii. sciittcrcd aldiif; tlic syn\|iatli('tic nerve trunks tlintiijrliout life, sin^'le (K. Fiy. ;J.'{7. The ninliac nerves fiiiiii the vm^iis iire lielieate, lliose of tlie s,viiij)allH'tie eoarse, in tiie (it'll re. has carefully studied oven ordinary sections stained in liaMnu- toxylin and eosin from the heart, alimentary tract (plexuses of Auerhach and Meissner), the tongue (FifT- l"-^-), the hlood-ves- wels, the bladder, the sexual organs, and elsewhere, must he familiar with these ganglion cells, and it is now believed that all <»f them which are to be found in the viscera, amounting to thousands, or ])erhaps millions, of elements, have had their origin in this nomadic way. The younger His* and Rom- berg have already worked out the mode of fornuition of the ganglia belonging to the heart, and have thus established for the first time a satisfsictory smatomicjal basis for the physiology of the nerves of the heart, and a starting point whence perhaj)s * His, Wm Jr., u. E. Ronib(>rfj. Hcitriij^t' /iir Iler/.iniiervatioii. Foil- schc. (1. Med.. Herl.. Rd. viii (IHilO). S. ^74 ; 416. Ills. W.. .Fr. Deimuistifilioii voii I'riipanitt'ii ii. Jlodellcii ziir Ilcrziimerviitioii. VimIiiuuII. d. Cong. f. iiiiu'rc Med. Wiesb., ix. 1890. His. W., Jr. Die Kiitwick(>limjf dos ITcrz- nervciisysteins boi Wirbeltliicren. Abhiindl. d. matli.-pliys. CI. d. k. siiclis. fii'sellscii.d. Wissoiisch., Hd. xviii (IBDH). No. 1. Kor a n'(-t;iit discussion con- cerning the innervation of the heart the reader is referred tc) the article by V. Lcyden, Krilisrhe Hemerkuiiifcn Tiber TIcrznerven. Detitsclie ined. Wehn- schr., Leipz., ii. iJeri., iJd. xxiv (1898) [DiscjiissionJ, \er.-Beil., S. 145-147. r , • ! i 1 i' It»:i TIIK NKIi vol's SVSTKM. tliosc |)ii^/1iii^ cliiiicul proltlt'iiiH in coiincctioii with tliu ciiniiiK; neuroses ni.iy l)t' lulviintajreoiisly approiielied (!''!;(. \'i'.\). It, is true tl)iit ho far as repirtis the I'xaitt liistory of the (h-vehtp- iiieiit ill the other viwcera, we are for the most part still pro- foundly ignorant, and a \ast and attractive tield lies here op(tii to I he investi^'ator. The sympatiietic cells dilTcr in inany ways, l)oth structural and functional, i'roin all other ;^'an^dion cells, a fact which is not surprisinj^ when we consider the peculiarities of their origin and of their environment. Whereas all othc^r nerve cells tend to he a^'j;re;,'ated in larjfe cell comnnuMties, more or less sharply separated olT from tlu' tissues in ^'etieral, those of the sympathetic; system are much moi'c isolated, l»ein^ {fathered to<^ether oidy in small heaps, while in many instances sin;,d(! cells maintaiidnf,' their existence far from all their fellows are completely isolated in the wilds of the hody tissues, ictaiidnf^ communication with the centres only hy means of tlunr non- medullated axones. I'nder such circumstances it is perhaps hut little wonder that these cells, like the pioneers of the huck- woods, should present peculiarities hoth in hahitus and con- duct. I I CIIAPTKR Win. ON- TMK MKCirAVK'AL I'ACTOKS OK DKVKLOI'HKVT AM) Till". III.MAN IIODY AS A Si; (liii|ilirautii — Scj^ini'iilal ion of tlic IhmIv — Mclaiiicn's — Myotitiiu's — Nt'iiniluini's — AiijjciiitDTiH's — S('l(>rotoint>» — Hiitcronn-n's — Doniuitoineres — Sclerozoiu's — Part playcil liy tlio tnar^iiml veil — [{I'lalimi Ici the |ii'i>l)l('iiis of lu>- rcility. Iv tlu' study of the liistorical (l('Vi'l(»|)iii(Mit of the nervous system, luccliiinicul factors, of a very siin[)li' nature, when viewed close at hand, are continually nu't with. The results of the hendin;^ and shapin}; of the medullary tuhe in its early staj^es are apparently conijiarahle in many respects. His thinks, with those wiiich occur in a siniph' ruhiier tuhe when suhjected to similar influences. The iteriplieral nerves in their outgrowth follow always, like hlood-vesaels in their advance, the channels of least resistance, hi regions where there is much bending of the body — for c\;ii:iple, in the neck and lund)ar region — the nerv(^ trunks converges to form the well-known plexuses.* If a bundle of nerves in its outgrowth meet with any obstacle in its path, such as a bar of cartilage, a blood-vessel, or the wall of a cavity, the bundle tends to divide, a portion of the fibres pass- ing on each side of the obstruction. In this way the curious distribution of numy peripheral nerves, entirely obscure before these embryological studies, becomes explicable. An instructive example of the light afforded in c(>rtain dark corners by his- togenetio studies is to be seen in the innervation of the dia- phragm. Von Baer f bad pointed out that tbe diaphragm in nuini- nuds develops at first in the neck region and that it descends * Cf. His, W. Ucber den Aufbau imsorcs XerveiiaystiMns. Bcrl. kliu. Wclmsclir.. IW. XXX (IKO:]). S. OnT: 990. Also in Wion. mod. Presse, 15d. xxxiv (189:5), S. 1477: IWl. Also in Wion. mod. 151.. Pd. xvi(tS9:?),S. 48:5; 407. f V. HaiT, K. K. I'l'luT Kntwiokolungsgcsoliichte dor Thieru' ; Poobach- tung und Reflexion., ii, S. 220. 14 198 m -■ { 11 Nil' 'If \ li>4 THE NKUVOrS SYSTEM. Ijitcr. IFc sniri;i'slt'- ment. Wiien the phrenic nerve grows into the diaphragm the latter is in the cervical region, and the distance from the al cord to the muscle to spii * (^idiat. O. I>u (li'volopponipiit do la portion ('('phiilo-thoraciqiio do l'oiiil)ryoii ; do la rorination clii diaplirajj^iiu', dcs iilovi'cs. dii poricardo, dii pharynx el do I'li'sopliajifo. .1. do I'anat. of piiysi(d.,olo.. Par., t. xiv (1878), pp. ();iO-()74. f Ills. \V. Anatoinio inonscIiIicluT Einbryonon. i, 1880; iii, 1885. t ;\Iall, I'". I'. l)ovol()pinont of the Iliinian ('(oloni. .1. Morphol., Host., vol. xii, 1S<)(1-!»T. pp. ;i<,»r)-ir):!. * Uskdw. N. roller dio l']nt\viokolunp NKS. IJ15 be iiinervatc'd is miniiiml. With the (lescciit of thi- dia- phraiim the i)hivnic lu-rvi' j^rows and jjoes with it, so that in t hi- adult \vi' havi' an ah(h)iiiiiial luusck' iniuTvatt'd hy a nerve of tho neci\. The \vori\ of His ujton the recurrent hiryna. Neal, H. V. Ihid., l?d. xii (. 18!)0). S. ;i77. 1 *'■ I,. !;■?>: A. a'! J 'II i 196 THE NERVOUS SYSTEM. vascular system (vascular sofjinent or iutorsogniont or angei- otonio), and in tlie skeletal system (hone sej^ments or sclero- tomes) ; it is also to be made out probably, though much less distinctly, in the alimentary tract (enteromeres) and in the in- tegument (dermatomeres). The overlapping or " telescoping " of the segments and of the segmental derivatives in general complicates the study in human beings, but witiiout the con- ception of segmentation anatomy can not easily be understood. VJ wr h sk sk cp ch mp ao vn ao Ih h uk mes'^ Fio. lli'). "Scliomes of transverse sections of yiiunjier and older Selacliian oin- l)r.Vi(S to illustrate tin' developineiit of tlie eliiel' jiroducts of t'le middle ter- niinii! layer. 'After van Wi.jlie and llertwin from A. Uanlier. Lelnlineli der Anatomic des Mcnsclien. lid. I, Leipz.. 1S!)7, S. TrZ, Fif:s. 15, l(i. i A, transverse section tlirouKli the re^jion of the fore i. muscle plate of tlie primitive scfjmenl ; "■, /one of growth by wliich the muscle plate liemls around into the skin )ilate, c/* ; vh, ^>iece unilinj; the primitive segments with the body cavity from which the tubules of the primitive kidney, nk, develoii; sk. skeletoKcnous tissue which iirisi's by proliferation from the medial wall of the uniting piece, rh; rii, fore kidm'y; ntk'. ink'', iiarietal and visceral middle layer out of the walls of which the mi'senchynu' develoiis ; Ih. liody cavity; ik, layer for intestinal glands; h, cavity ot' the primitive sejjment ; uk. tubules of the primitive kidney; iik, jioint of separati;ht siile ; tr. connection of the tulmles of the jirimitive kidney with the boI(in<:hiui])leure — i -^^5^ VI Mtnibr. reuiiiens. 0^' J^ ■ ^ enii n)iihili((ili.f. l'"i8 TIIK NKUV'OUS SYSTKM. ("orrosjmnding to each niotaniore there is an artery and vein (vascuhir se^fnieiit or anfrciotoiiu"). Further, each metamere be- hind the iicad receives the motor root and the sensory root of one s})inal nerve. Tills s])inal nerve, inchiding hotli tlie motor part and sensory part with its spinal ganglion, together with a portion of the medullary tube to which it l)elongs, represents one neural segment or neurotome.* Til' lines which in the eniliryo se])arate the primitive seg- ments or nietameres from one another are known as the inter- segmental lines. In these develop later those myosepta or myocommata which se])arate the myotomes from one another, and in the adult give origin to the ribs and the intermuscular septa. The muscles of the body are divisible into (1) skeletal and (2) visceral muscles. The skeletal musculature, which includes the eye muscles, the muscles of the trunk and of the cxtreniitics, arises from the myotomes. The visceral musculature, which includes the mus- cles of the alimentary tract and of the iilood vascular system, * As will he pdiiitcd oul in Soclidii \'i, Ilcml lliiiiks that ti coni|mrisi)n of liis sludifs with tliosi' of Slu'rrinjjton indicate tlmt the soj^ineiit in the s|iin;il pord does not oxaelly correspond to tli(> ncrvd roots in its peripheral relations. a!U tit i'l B HISTino of bono iin.l ninsc!.' s(>k- , ,\ " ', ., , i\u-nt. (After A. Riiiilicr. Ltlii-lMicli /,., dorsal musinilature (Fig. 128, A 1, B (1.) make up the parietal musculature derived from one myotonu^ The visceral musculature! corresf)onds to the mass marked (<>) in the (igur-!. The division of the parietal musculature into a dorsal jior- tion and a ventral portion separated by a connective-tissue septum is very much more distinct in lower vertebrates than it is in man. The line of separation betwi^en the dorsal and 1M!(7, S. !()(), Via. IDS.) A. - c, hixly 111' vcrliln'ii : rn' ; r, iirciis (■(pstiiniiii ; A', iirciis visccralis ; /, ilorsitl purl III' iimsclc si-j;iii(iit ■. .'-'i, vcn- Iral pint uriiHiscIc scuiiniit willi its ilill'cr- cnt siilxlivisiciiis : .;, prcvcrlclinil ; //, siilt- I'listiil ; .', iiitt'rc((st;il ; .1, piirtiiiii for cx- Ircinity; C. visccrMJ iimsclc. 15. — Tlic imrictii! iiiusclc scfjniciit liniiiylit to its siiiiplfst expression ; (/, doi'Siil p;irt ; r, Ventral part. 200 TllK NKllVOUS SYSTEM. ventral muscnljiture is known in these animals as the lateral line {SeitcnJinie oi the (Jennans),* and here arc* situated an im- portant series of sense orf;ans known as the " sense organs of the lateral line." It is not unlikely that tlie so-called branehial sense organs (Beard), which appear temporarily in the region of the head in young end)ryos of higher forms, correspond to the sense organs of the lateral line of lower animals. Each myotome has a neurotome corresponding to it by which it (along with the skin and other adjacent structures) is innervated. The ventral and dorsal roots of a spinal nerve unite to form a common trunk, the mixed nerve stem. The latter, the pcriplicral representative of one neurotome, divides into a dorsal ramus and a ventral ramus. The dorsal ramus iu- Dorsal '•.. til iisele Jwlil. Kdiinis . iloiisd- tin Herri SllilKlliS. Hdiiiii.i veii- tralin lierri spiiutlis. I'eiitrnl • iiiiiiirle fiekl. Myoseptum. Dorsal liinb. Strntiiin (lorsdtf. l.n'al blaste- tiiii {aki'lrlid /)/«/<■ I. Vfiitnil limh. Stratum vciitralf. Fi(i. 12it. — Trunk scfjiiicnt of liiinian cinliryd witli niic iwiir cf nerves ;in(l tlie niilinient of the iiiiiseiiliitiire of one extremity at the sixth week, seheinatie. (After. I. Kollniailli, r.eiirtiueh (1< r lMit\viekehin},'s;;esehi(iite (K'S Mensi'lien, Jena. IKlls. S, ^>Si), V\)r. Kit. ) nervates the dorstd portion of the myotome, the ventral ramus the ventral portion of the myotome. Fig. 120. At the time the union of the neurotome with the myotome occurs, the latter is in close proximity to the medullary tube. * Corresponding to this we have in htinmn beings the deep layer of the fascia itimliodorsalis separating the dorsal iiiiiseuhitiire of the trunk from the ventral. IlISTOGEXRTir KHLATIONS OF TIIH NKrUOXKS. 0()l and the distance t<» be traversed by the outgrowinj^ nerve is niiiiiniiil. As development proceeds, however, the muscles ciiangc tlu'ir position, in hirge part owing to their skeletal at- tachments, and become farther and farther removed from the places in which they originate. The displaced myotome deriva- tives carry their nerve branches with tiicm ; where the muscle goes, the nerve accompanies it. In the adult the easiest clew, as a matter of fact, to the myotomic origin of a given muscle is its nerve supply. Some of the muscles of the adult body have been derived from more than one myotome. 'IMius, those arising from two myotomes are known as diplomeric; muscles (e. g., the supra- spinatus and infraspinatus muscles), those from more than two myotomes as polymeric muscles (e. g. the pectoralis major and minor muscles). In such instances the diplomeric or polymeric origin of a muscle is indicated in the adult by its diplomeric or jtolymeric innervation, for muscles derived from more than one myotome are innervated by nerves derived from the ventral roots belonging to more than one neurotome. The origin of the muscles of the extremities and the inner- vation of these muscles are of especial interest. For our knowl- edge in this connection we arc much indebted to Dohrn,* 1'. .Mayer, f Kastner,J Paterson, * van Wijhe,|| van Hemmelen,'^ * Ddlirii. A. Studion zur I'l-ficscliichti; dcs \Virl)t'ltlu('rkr)rpers. VI. Die pnui'ij^i'ii luul unimairn l-'losscn der Si'lacliior. .Mittlicil. mis dcr zool. Stiitioti zu Nciipcl, Md. V (1H84). Also, Die unpaiirc Flosso in ilircr Bcdi'ii- tung filr die lU'urllii'iliiiif^ der jifiu-alofiisclieii Stcllmifj dor Tiiiiir'aton und des AmpliidXiis, und die Ui-stc dcr IJcckfiiHosse hei I'etromy/on. Ihid., I5d. vi (tHH,-)). ^^ Mayer, P. Die unpaaren Flosson der Selaciiicr. Mitthcii. aus der zodl. Station zu Xeapcl. Hii. vi (1885). X Kiisliicr, S. Felier die allj^eineine Entwickelung der Rumpf- und Schwanznuisculatiir bei Wirheltliicren ; niit tu'sonderer Ueriieksiclitiijfung der Selachier. Arch. f. Anat. niid I'liys., anat. Alitlieil.. I.eipz. (1H!»2). S. \m- 'i'i'l; also I'elier die JMiIstelumjr der Fxtreniitatenniiiseulatin' l)ei den anii- ren Ani|)liil)ien. Verliandl. tl. anat. Gesellsch., ,Iena. 1H!»!{, Bd. vii, S. 1!);{-199. * I'aterson, A. >[. On the Fate of the :Mns(le j'late and the Develop- ment of the Spinal Nerves and Ijind)-i'lexnses in Mirds and Mammals. Quart. J. Mier. So.. Lond.. n. s.. vol. xxviii (1HHT-'8H). pp. l(»!»-12ft. II van Wijhc.r.W. Ueber die l\resodermse<;inente und die Fntwiekelung der Xerven des Selaehierkopfes. Verhandel. d. k. .\kad. v. Wetensch. .\mst., Deel xxii (188;{). pp. 1-;S0. ^ van Hemiuelen, J. F. Ueber die Ilerkunft der Kxtremitiiten- und \ I u\ I \ h 202 THE NERVOUS SYSTEM. KoUniiinn,* iiiid in Aiiicrica, Ryder,! ii>*r uicht knorj)olif; vor- j;;el)ii(h'te kelettheih' in deti Flosseii (h'r 'reicostier. Aroh. f. Mikr. Anal.. Bonn, Bd. xiii (1893) ; also The nevelopnient of the Fins of Teleosts. The Jolins Hopkins rniversity ("irciiiars (1894). No. Ill ; idso The Metamerism of tiie Dorsal an' 'he \'entral Longittidiniil Muscles of |}i(> Teleo.sts. The Johns Jlopkins I . .versity Circuhirs (1894), No. Ill ; also Die Entwickeliinp der unpaareii uiid paarijren l''lossen der 'I'eleostier. Arch. f. tnikr. Anal., Bonn, Bd. xlvi (189.")), S. .WO-STS. HISTOGKNKTIC RKI.ATIONS OF THK NHUHONKS. 2<)3 main from muscle huda which are pinched otf durinji; dcvolojv ment from the trunk myotomes. According to Harrison, a cer- tain number of tlie muscles of the extremities are derived from the unsejfmeiited nu'si'iichynu) rather than from the myotomes. It seems likely that tin; relations of myotome to neurotome hold also for the extremities, but thus far, owing to the ex- tremely complicated processes of development, it has been im- — ■ ^ t m ■ r r /( ^r^.ri'./J: Fi(i. i:?i. to till Fields oil tlic fxtci'iiiil surface of tlie os iiiiioiuiiiatlliii corresixiiKliiiK attiu-linient of llie \arioiis muscles. Tlie llnuiKii-luiiilio-sicral nerves littli) Koveriiiuf; the individual muscles are indicated. (.Vfter L. Hoik, lol. .lalirl)., Lcipz., I?d. xxi, Isid, S. :.*t^', Fiji. I.) possible to determine this iil)solutely. Here also in the adult structure it seems probable, however, that the neurotome supply, i i K .1.1 It ill! 4 2(14 THK NKRVOUS SYSTKM. when it ran bo ostiiblisliod, is a safe fjuido to follow in drawinpf eoiu'lusioiiK as to tlic nivotoniic oriiMn of the various niiisclos. Fid. IIW. -( )iitci' Mirfiicc cif OS iiiiiinniiiatiiin. Tlii' lines luiiiiid llic iirciis in wliirli ari' fcmiiil tlic iitlacliniiiits dl' the nillscic masses y tiu' l:itli to tlie llttli tlioi'iico-liimlio-sienil nerves. The Kil' "^ ^ fv; h Fid. 1153. — Hccdiistnittcd fiiriii of pilvis nf Ihiiiimii I'li'lus, illiislviiliiij; skeletal ureas correspiiiKliii}; til (lii^ iiiyutoines iniiei'vated l).v (he l:.'tli-litlli iliorarn- limitio-.siicnil nerves. (.Vl'ter I., liiilk, M.')(i, KIk. :5. I tro-(lorsal direction the followinfj muscles: (1) M. sartorins; (:i) M. tensor fasciie lattv ; (:5) M. glutanis minimus; (4) M. glutajus medius, (5) M. glutivus nuiximus ; ((i) M. piriformis. * Hi)lk, \i. Rezicluuifjon zwisclicn Skeli^t. Miiskuliitur iiml Xervcii ilcr Extreinitiitcn, tiarp'legt am Hofkeiif^iirtel, an desseii ^Iiiskiilatiir. sowie am Plexus lumbosacralis. Morphol. Jalirh.. 15(1. x.\i (1804), S. 241-277 ; also, Kekonstruklion dor Sejjmcntinin,!; dor Gliodmassoniniiskulatiir, dargidojjt an den Mnskeln I'es Obonsohonkols und des Seliultorjjiirlels. Morjihul. Jahrb., Loipz., Hd. xxii (18n4-'9r)), S. 357-379; also, Die Sklcrozonie des Hu- merus; zugleich oin Roitrag zur nildungsgcsoliichto dieses Skeloltlioilos. Mor|)hol. .lahrb., Leipz.. Bd. xxiii (189.')). S. 391-411 : and Die Sogmental- dilTerenzirung des menschliehen Kumpfes und seiner Extroniitaten. Mor- phol. .lalirb.. Leipz., Bd. xxv, II. 4, S. 405. irr u 200 TIIK \KI{ vol's SYSTKM. 'I'licsc JtiiisclcH lire innervated by ti corresijoiidiii',' HcriuH of veii- tnil roots, us is sliowii by tlie iH'('oiii|tiiiiyiiij; tiil)lu. Tahlk 1. SlM'illl H(M|UI'I1CI !'' n;'li:''''.:rjn .•.'.''',,I''.r"'i'iT,.!ll''i'.','\'!!If ImH-rvUi r n,.. mius..|..h l.y tl.orac... 1. M. siirtiiriiis. 2. .M. tensor fascia' lata'. !l. M. glula'us iiiiniiiiiis. 4. M. jjliila-us nicdius. 5. M. jihita'us maxiiiiiiH. (i. M. |(iriforiiiis. 14 15 1« (17 1(1 17 Id 17 IM 17 IM 1<» IH 1!) A^'iiin,tlie follo\viii<^ muscles are siiecessivoly attjujlu'd to tlio pubis Jiud iseiiiuin in vciitro-dorsid direetiou. (1) M. reetus ulxioMiiiiis, \I. pectineus, M. adductor loii^nis, M. iidductor brevis, M. gracilis, M. adductor niagnus, M. ob- turator externus, portio is();!. Fi";. li. ) lines corresponds to the myofommata or mesodermal septa which in the em1)ry() separate the myotomes from one ujiother. It seems likely that the distribution of one myotonu' stands in a detiuite relation to that of a jfiven sclerotome. The surface of the bone givinj; attachment to the muscles deriveil from a giveii myotome is known as a sclerozone. in I'^if^s. l.'il and V.Vi the various sclerozoni's on the outer surface of the pelvis are demonstrated. It will be noticed that the muscles attached to the ventral surface of the pelvis have been derived from myotomes more anteriorly placed, while those attached to the dorsal part of the pelvis have orijjinated in myotomes more caudally situated. That the relations are much more simple in the embryo is not 8urprisin<;, and Hoik lias done anjitoiny an important ser- vice in pointing this out. In Figs. 133 to 138 the tVetal IIISTCHJKNKTIC UKLATIONS OF TIIH XErUOXKS. 2(>9 conditions ari' illustratrd. Tlu* scU'rozonos at this ju'riod ari- limited by straight lines. The Itone is nuich sinii)lt'r in form, tiio complexity of the later relations of the museles and nerves l)einj; in larjjfe ])art diu- to skeletal alterations. For a descrip- tion of the { I) prozonal, ("J) diazonal, and (:>) metazonal nerve trunks* ((1) N. femoralis, (v*) N. ohtnratorins and (;5) X. ischiadieus, Nn. {jjliitu'i and N. obturatorius internus) and the metOianical factors which have led to the curious distributions of muscles and lu'rves in the adult, the ori<^iiial article of liolk may be consulted. An e.xcelleiit epitome of portions of the re- / ^••» Fk;. 137. — Ari'iiiiKciiiciit n'" tlic diii/niuil vi'iilr;il N. iiiiHirntoriiis. (After L. Udlk, Miirpli'l. ,)Mlirl>., liil. xxi, isitl, S, -Mri. \'\fi. 7.) search is givon in the hist edition of Rauber's Text-book of Anatomy.f The s(derozonic anatomy of the humerus is indicated in Figs. V.V.) to U'-.*. Bolk believes that the mesenchyme out of * Noincticliitiirc of Max Fi'irhviiifriT. •f Haiil)or, .\. Lt'lirl -luli dor Aualoinie des Jleiisclieii. \'. Aull., Leiiiz. (IbliH). B(l. ii, S. 5<)0 ir. 15 .flJ 210 THK NKRVOUS SYSTKM. f r ^01 f^ uli w i' \<< which thiit nortion of the .skeleton which corresponds to a Bclerozone is formed arises from the same segment as tlie myo- mere belonging to tlie sclerozone, hut will not assert that the whole mesenchyme undergoes segmentation — that is, that a defi- nite metatnerism of its whole substance can be (k^nionstrated. It appears that the humerus is formed of the mesenchyme corresponding to tiie fifth, sixtii, seveiitii, and eighth cervical myomeres. It is a curious circumstance that of the muscles of the humerus in the proximal part of the bone, all are derived from tile dorsal layer of the musculature, noiu' from the ventral {(/. stratum dorsale and stratum vcntrale in Fig. \'i\)). The only nuisclo of ventral origin at the proximal end of the hu- Fi(i. 1H.H. — Arriiiificini'iif iirtlic vcnfnil and dorsil |)i'iizonal, diazonal. and nicta- zonal norvfs. lAftvr L. Hoik, Murpliol. .lalirh., Hd. xxi, 1H!»1, S. ^'(iti, Ki^. 8. > merus is the long head of the biceps, which comes from the stratum ventrale derived from the fifth and sixth (cervical myo- meres. Even this is not connected with the ventral surface of IT VUi. l.J!). «'ll( l(.V( <>/' (Ik |)i>si(i(iii Morjili,! merus, tli sections o luture, cv( '•"id that firrangeiiK 140 to \A-i Tile ni( concerned to be thoi; IIISTOOKXKTIC UHLATIONS OF THE NEURONES. 211 the axial hlastoina, but lies instead in tlu- bicipital fjjroove (sul- cus int('rtubci'cularis),a fa(!t which Molk looks upon as evidence that the ventral mass of the axial blastema has in this reirion not been (lilTereiitiate(l. Dctspite the fact that the sclerozones lonjfitudinally considered take a tortuous course down the hu- i ) / Fi(i. ll?il. — Six transverse seetiinis llinniKli a rinlit upper arm, /- 17, at tlie (lirttT- ciil levels indicated in the iiPUfjitiidinal view of tlie ininienis. TIk^ relation (iC tlie ((larl<) ventrnplaniuii to the (eoliirh'ss) diirsoplanuni. as well as tlie. IMtsitidli nl' the t (i eervieal sclerozones, are illustrated. (Alter L. Molk, Morphol, .lahrh.. Leipz., Hd. xxiii, 1S!I.^), S. 401, Fit;, -l.) merus, tliey are reciprocally regularly iirranfjed, its the cross sections of Fij;. 1:5!) show. Tliat the ventral and dorsal niuscu- liiture, even in the adidt, form two sharply separtible j^roups, iind that in each of these groups the primitive segmental arriingement is discoveriible, will be clear from a study of Figs. UO to IX-i. The most wonderful, however, of all the mechjinical factors concerned in tlie development of the nervous system would Beem to be those which, according to the ingenious liypotheses of ■ t ■ r ■ Mi •' i '■ *«••■••* ' t 4 U 212 THH NKUVOrS SYSTEM. f ;• llis, are connected with the niarf^inal veil. It is almost like a fairy tale to be told that the direction of many millions of white fibres within tlie central lu-rvous system diirin<,f dcvelop- nu'iit (lei)ends upon simple obstructions otlVred at the i)ro})er time and in the right degree to the outgrowing processes of the neurobhists. We have seen the long distances which certain of the axones have to travel from their cells of origin in order to reach the cell bodies and dendrites of tlie other neurones which they have to influence, some of the axones of the fibres of the pyramidal tract, for instance, having to extend !« FUi. 140. — 'rniiisvcrsf scctidU tlinmKli tlu' iiiusciihitiirc nt' tlic sliiiiildcriiiHl clifst. Tlu' liiavy (lark lini' indicates the limit l)cl\vi(ii vi>. rit.. Via. 12. 1 system wliicli we believe to be functionally concenu'd in his mental processes ; and particularly when we reflect that both M 214 THE NERVOUS SYSTEM. :|'i ¥ f. ^\ k ^ the bodily and montiil i liiiractoristics of the individual are lioreditiirily transmissible. As His lincly puts it (tiio trans- lation is free) : " It is exactly in these last considerations that the key for the correct understanding of the special relations is to be souj^ht. Like every other orfjjanic foi-niation process, the oriction. In such a mechanism one pro- cess goes over into another ; each appears at a given time as a definite sequence of processes which have gone before, and at the same time as the necessary determinant of ])rocesses which shall come after. And even where processes of apparently dif- ferent origin and significance reciprocally influence one another, yet they all act at the place assigned to them by the general law, and do no nu)re and no less than is ordered." It is now necessary to hasten on to the consideration of the neurone as the unit in physiological and pathological processes. THE The fell met .S|||,] of fi Foii Pathol. nial aj) in itsel belief tl to any ^ the brai ring an bears w of a lar upon a organisn to one } special other pa led to a ogy, was the nerv( tiiiu' vcr sort of V * Viivh l<),i,MScllC III 440, 8vo, Ji( '.Ui, . SE(^T[()\ V. THE NEURONE AS THE UNIT IN PHYSIOLOGICAL AND PATTIOLOGTCAL PROCESSES. / 1 CHAITKR XIX. INTUODl'C TOUY. The coll (lootrine and tlio iiitvous system — I'hysiolofjy of tho neuroiios — The iiit'tal)olisin ami nutrition of ni'iiron(!s — I'MTih-I of altoration in blood supply — The food stuffs and I'xerotory products of neurones — Constancy of function despite continual cliunj,'e. P\)UTY years have passed since Vircliow, in his Cellular Pathology,* gave expression to the conviction that every ani- mal appears as a sum of vitiil units, each of which exhihits in itself all the characteristics belonfjing to life. It was his belief that the character and the unity of life are referable not to any single locality of a higher organization — for example, to the brain of man — but rather to the definite constantly recur- ring arrangement {Einrirlihi)i(i) which every single element bears within itself. According to this view, the composition of a liirger body, of the so-called individual, always depends upon :i social arrangement ; it represents, in fact, a social organism, in which there is a mass of single existences related to one another in such a way that every element litis its own special tictivity, and each, even when incited to activity by other parts, does its woi'k of itself. AVhile this concept, which led to a revolution in the prevailing ideas regarding pathol- ogy, was accepted for the body in general, its applictition to the nervous system, and especiidly to the brain, was for a long time very little emphasized and only recognized in a vague sort of way. And indeed this can hardly be matter of sur- * Virohow. H. Die Cellularpatholoj^ie in ihrer Begriindung auf physio- logische un{i pathologische Gewcbelehre. Zwanzig Vorlesungen., xvi, pp. 440, 8vo, Berl., 1858. 315 If" f 1 1(1 i H '|j' 2U> THE NERVOUS SYSTEM. prise Avhon we consider the enidencss of kjiowledfje at tlmt time of the structures coueenied. Mut with th(( estiihlisliineiit of the neurone eouei'|)l uf tiie nervous system tlu' iinportjinee and applieal)ility of such a view of its constituent ornts or constituents which had faded from consciousness, hut could he reinstated hy secondary suggestion hefore the cells were destroyed or removed, can afterward he no longer revived. This fact would almost justify us in helieving that the " mem- ory traces " are in some way or another laid down in the neurones, and are actually organically connected with them. These neurones with which the memory traces are in some way associated are continuously uiulergoing the metaholic changes, such as have just been described, and the wonder is not that we have such poor memories, but that they are as good as we find them to be. Far from being surprised that the reproduction of past experiences in consciousness is occasionally unfaithful, we can only wonder how it can rea(di the degree of accuu'acy with which we are familiar. While emphasizing the maintenance of a certain constancy of function, and consequently of structure, despite the unend- /I A, ;rr J)' 2l>() THE NEItVOUS SYSTEM. iiij; clicinical altcnitioiis jjoin^ iici>s. Miit even ill tlu'se ul)iioriiial states it is tlu* eoiistaiicv ol' tiie fiiiKs tidii wliicli impresses us iiinst ; the faet that, ;:iveii a nervous system iiiate(lly ilo exercise an impnrtaiU influence iijion ile- vi'lopmeiit. i)iit the character of the resjionse is dete/mined by the inherited organization. f If the conviction expressed in the text be well founded, then, broadly speakiuf,', (IS /(/,s ni'Hfdin'H arf. ko //if nuin in. In this sense, (ioethe's words, in the mouth of Mophistopheles, can be made to bear a new and almost jiro- phetic sif^iuficaiicc : "Dii bist am Hnde — was Du hist. Sctz Dir Perriicken auf von Millionen liockcn, Set/, Deinen I''nss auf elleidiolie Socken, Du bleilist (loch immer, was Du liist." X The same remark has already l)een nuide regarding sociology in Social Rights and Duties, by Leslie Stephen. '■•I i J,, K^t ( i • rt' 4 •-'. t' ' ! 222 TIIK NERVOUS SYSTKM. That the noiirologist is ulniost infinitely distant from any ap- proximation to su(th astronomical accuracy witli regard to the nervous system it is needless to remark. That he may never attain to such omniscience is altogether probable. But the fact that he lias already learned that in the nervous system certain causes are followed by certain definite effects almost with mathenuitical accuracy should encourage and stimulate him to further research with the hope that the intricate laws in question may gradually be rendered less obscure and vague. CIIArTKK \X. ON TIIK DKOEXF.RATIOK AM) UIXJENEKATIOX OK NEURONES. ("Iiaiigcs which oc-cur in a jiai'l scvoretl from thi' rest of the iiciiroiii' — Wal- Icriaii (h'goiienitioii — Tiirciv's degonenit'on — KITot't on tiip wiioli' neu- rone of injury to one or nioro jiarts of it — ("haiigcs foHowinir amputations — Kx]icrini('nts of v. (Muhlcn, l''ort'l. and otiicrs — Apiilication of method of >[archi to tlie study of the central stump of a divided nerve — Studies of Nissl on changes in the cell bodies of neurones after section of their axonos — Klfects of injuries to dendrites — StiKJies of Warrington and others — Kffeols of injuries to the cell bodies of 1 lie neurones — Changes in lumbar cord after ligation of abdominal aorta^l']x|)erimental pro- duction of secondary degenerations — ^'alue of the metiiod of Marchi and the method of Nissl for pathological studies — The neurone as a whole a frophii' unit — Regeneration of nerve fil)res anil nerve cells. As ri'<,'!ir(ls the trophic rchitioiis of the neurones, it may witliout further preanihle be asked (1) How far is the nutri- tion of tlie individual portions of a neurone aifected by an interruption of their conneetion Avitli the rest of the neurone? (2) How far, if at all, does the whole neurone suffer as a result of injury to any one of these individual constituents? In iittemptinj; to reply to l)oth these (piestious it will be found that we possess data to draw upon which rejjard not all, but certain only of the individual portions of the neurone. We shall find, too, that an answer to one question must from the nature of thinjrs include ii re])ly to the other. That the formu- lation of the two (|uesti()ns as just adopted is not superfluous will readily be fxranted, in that the c()iiteini)lati(ni of the subject from the two different standpoints will help us nuiterially in umlerstaudiuf? the reciproctil relations which recent research has (lenu)nstrated to exist. As long ago as IS;}*.), Nasse * ami Valentin f had jn'oved that * Nnsse. Ueber die \'eriinderungen der Xervenfasern inicii ihrer Durch- sehneiilung. Arch. f. Anat.. Thysiol. u. wissensch. Me 4^1w> «« .*^ (Ait.r ThoiMM. A T.xt-Mnok of tlic central end tlnm to the first Tilt lioiofi.v and Patliolofiicai Aiiat- node of Kauvicr. If a sensory oiiiy, vol. 1, p. 50.5, l-Xii.'MH.) . • , ', nerve is cui t'^'-ough peripheral to a spinal ganglion there ensues complete degeneration of the sensory fibres as far as tlic sensory surfaces in which they * Stiiniiius. riitcrsucliuiif^cii Uber Miiskeliviztmrkeit. Areh. f. AiiaL, Pliysiol. 11. wisseiisL'li. Med, Berl. (1847), S. 44:i-46'J. \ Waller, A. Experiments on the Sectidii i>f tlie (il(issopli!ivyiij;:e(il and Hypoglossal Nerves of the i-'rog. ami < Hiservations of the Alleralions pro- duced thereby in the Stnielure of their Primitive Fibres. London, Edin- Fl(J. 14:?. — Wallerian defieiieratioii of nerve lilirts afttr section. /, nor- mal iK'rve tilirc ; // and ///, lilires slio\vin>; ditferent decrees of (h'fieii- eration ; >'. neurilemma ; iii, medul- lary slieatli ; .1. axone; k. nucleus of neurilemma cell : /., markinnof Laiilermann ; A', noclc of Kanvier; 3 TIIK XHrUOXF, AS TIIK UNIT. 225 ho^jfin.* It was further .shown l)v siiiiilar oxpcrimouts that if tho dorsal root of a spinal iicrvt' was cut throuy tiie work of His, who demon- strated that the axone of the peripheral sensory tihre, the spinal ganglion cell, and the axone of the nerve tibre of the dorsal funiculus all represented parts of one and the same cell. These degenerations in the domain of the peripheral nervous system were eai'ly shown to occur also within the confines of the central nervous system, the secondary descending degenera- tion of the i)yraniidal tract established by Tiirck f and the as- cending secondary degeneration in the spinal cord after trans- verse lesion being (|uite analogous. We now know that the axis cylinders of the dorsal root iibres, with the exception of the few centrifugal fibres present in them, are axones of neu- rones whose cell bodies are situated within the spiled ganglia. We know that the axones of the motor peripheral nerves arise from the cell bodies of neurones situated within the ventral Imrgli, and Dulilin Philosophical Mnfrazinc. vol. xxxvii. Xo, 247, j). G."). .Inly, 1850. Also in Philosopliical Transactions of the Royal Society of Loinlon. law, p. 42.]. and in tlio IMinh. M. and S. .T.. vol. Ixxvi (lS.')t). ].p. ;!(ii)-;!T(i._ Sur la ri'produt'tion di's norfs ct .snr la striioture et les fonctions dos jran- jrlions s|)inanx. Arch. f. Anat., Physiol, u. wisscnsch. Med., licrl. (18.12). S. ;i!l'^-4()I; Conipt. rond. hchd. di's st'anccs do I'Acad. d(>s sc. Par., t. xxxiv, p. 675. — Nouvelli! mothodc po\w lY'tude du systoino ncrvonx applicahle a rinvi'stii;atioii dc la distribution anatoiniquc dcs cordons ncrvcnx. pt an diagnostic des maladies du systctnc tHM'vonx. pendant la vie ct apres la mort. Conipt. rend, helid. des swuipcs de TAcad. des se.. Par., t. xxxiii, 1851. p. G()6. — Experience sur les sections y Wcifjcrt'siiu'tluKl tlinnif.'li the cervical cord of n woiiiiiii, showing; secolidary degenerations t'ollowin;; coin]pr(Ssion of tlic cord at the level of tlie second tlioracic se^Miient. (After S. {{osenlieini. ) /•'. ij.. I'aseiculns fjnieilis; /•'. ils.. fasciculus cereUellosiiinalisi direct cirelicllar tract I : /•". c.s. /., fas<'iculi: i cerchrosiiinalis lateralis ( lateral j." • i i l.yrainidal trad ) : /•'. rl. (1.. fasciculus vent rolaleralis PHltlOn includes not (iow.rsi. Since the (il.res iu the fasciculus Kra.ilis „nly the maluaxone, and many ol those 111 the lasciclilns cerehellospiualls '' _ ' and in (iowers's tract dejiencrale upward from the but also its tcmii- site of lesion, cells of origin of the defieni'rated 1 i. ii • i.\ tihresmust he situated below the level of the second nalS, tOgCtllCr With th,uaeic ,s, -nu.ut. The Rvranii.lal tract is not de- ^hc collaterals and fielU'rated ; the cells whuh jjive origin t[iiniere. llclsingfors (1885), pp. 112. 7 pi., 8v(>. J Tooth, Ho\vard H. The Gulstonian Lecturps on Seeondnry Degener- ations of the Sf)inal Cord. Tiondon, •!. and A. ("hunhill (1880), pp. 1-71 : also in Urit. M. .1.. Lond. (1880), i. 75:5: 825: S7;i. •Notthaft, A. V, Nene rntprsncliiing(Mi iilier den \'erlauf d(>r Degener- ations- und Hegenerali(ins])roc«'ssc am vcriet/teM |)ei'iph('ren N'erven. Ztschr. f. wissenseh. Zool., lid. Iv (180^}), S. i;)-l-188. Fi(!. 11."). — Scctidu stained l).v Wcificrt's nictluid tiii'(iii;;li the luiiilKir curd of a woman. sIkiw- inj; scccindiiry (IcKcni'iatinns rolldwiiiK cnin- lircssicin ol' the cm^l at the level of tlie second tlionicic segment. i Al'ter S. Ivosenlieini. ) Fascicidns cereUmsiiinalis lateralis ( /•'. ex. I.) is (h'frene rated. The cells of ori;,'iii ol' its axoiies are situated ahiive the lesion (in the cerehral cortex). II c:„„ ,1... // I TTKi .a»m i i !tl 1 i r 22S TIIK XHUVors SYSTEM. droplets iiloiitr tlio wliolc length of the ncrvo. .Miiltipliciitioii of tliL' iiiU'lt'i of tlie lU'urik'iimiji is i-vidciit iit tlu' fourth diiv. At the sixth or seventh day liqiiofiictioii of tiu' inyoliii comim'nct's, jiiid this continues until the sixtieth or eightieth day, l>y which time all the myelin lias hecn liquefied aiul a lar^c part of it has heen ahsorhed. After three or four months the myelin has entirely disappeared. During the secondary degeneration of tlu' wliite iil)res within the central nervous system there is a proliferation of the neuroglia. The multiplication of the neuroglia cells hegins in the white matter, according to Ceni,* some forty-live or fifty days after the lesion. The neuroglia cells cease to multii)ly at about the humlredth day, after which there is a gradual disap- l)earance of neuroglia nuclei with gradually progressing scle- rotic change. Owing to the shortness of the dendrites (unless we look upon the peripheral sensory fihre as a dendrite), we possess no exact studies concerning their fate when severed from the cell bodies of the jieurones to which they belong, but we have every reason to l)elieve that they would undergo speedy ami complete degeneration. Viewing now the question from the other side, let us ex- amine and see in how far the injury to one portion affects the nutrition of the whole of the rest of the neurone. The study of portions of the nervous systems from individuals who had died a certain length of time after amputation of an extremity soon afforded data which apparently stood in direct contra- diction to the doctrine of the trophic centres as formulated by Waller. For, while Waller demonstrated the cojuph'te degen- eration of the })ortion of the nerve hl)re disconnected with the trophic centre, he maintained the integrity of that portion of the fibre left in connection with it. f ♦Ceiii, C. Sur los fines alleration.s liistoloj^iqiies de la inoelle i'pini6rt' duns li's tk'gt'nt'rcsoonoos st'condaiivs asccndantes ut ilcsci'iiilanti's. [ Abstr.] Arch. ital. de bio!., Turin, t. xxvi (18!t(>-'!)T). pp. 97-111 ; also in Areh. per le se. nied., xx, Torino (1806). i)p. iai-i!M. f Tliis seemed to accord well with tiie well-known fact that some of the sensory nerves proximal to the lesion are capable oi functioninjj for some time after amputation, producing sensations which often may jjive rise to no little mental disturbance and alarm on the |iart of the patient, since irrita- tion occurring in the course of a sensory nerve fil)re is attriliuted in con- sciousness to stimulation of the sensorv surface from which it has ijeen in (I TIIK NEI'UOXK AS TlIK I'XIT. '2'2!> As I'iirly iis l.S'ilt Mcnird * had noticed tliat in tlu- spinal ncrvt's snpplyini; a lind) ain|tutati'(l sonic time before, there was at antopsy distinct atrophy of the ventral roots. N'ldpian, Cruveilhier, llayeni and (lilhert, Dickinson, Friedlaender and Ivrause, Honioii, \'anlair, (irij^'oriefl", and many otluT investi- {jators busied themselves with the subject, and came to conclu- sions which were often at variance owin<;, as has been shown l»y Marinesc(),t to the fact tluit the authors studied and described ditt'ereiit phases of the alterations. Marinesco convinced him- self that after amputation of a limb, or after section of a pe- ripheral nerve, there occur in the central jmrt definite patho- logical changes, the intensity of which (le]>ends upon the species, and especially ui)on the age of the animal and upon the length of time intervening between the injury and death. The younger the individual at the time of the amputation and the longer the time elapsing between the operation and. death, the more marked are tlu' alterations. The degeneration in the central stump of the divided nerve, although it appears Jiiuch later than that in the distal portion, presents similar morpho- logical appearances and is apparently an analogous process, although — and herein lies the vulnerable point of the Wallerian doctrine — the central end still maintains its continuity with the " trophic centre." Not only do the sensory fibres distal from the spinal ganglia degenerate, but after a time large numbers of fibres in the dorsal roots proximal to the ganglia and their corresponding fibres with their collaterals and ter- thc lial)it of conducting impulses. The superstition referred to in the old play — "Still in his dead hand clinched remain the strings That thrill his father's heart — e'en as the limb Lopped off and laid in grave, retains, they tell us, Strange commerce with the nnitilated stump Whose nerves are twinging still in maimed existence" — is not yet obsolete, as any one familiar with many of the rural districts of this country can testify. S. Weir Mitchell has given an interesting account of some of the sensations described as coming from the lost limbs in his mono- graph. Injuries of Nerves, and their Consequences, 8vo, Philadelphia. 1872. * Herard. liull. Soc. anat. de Par., (piatri^me annee, Bulletin No. 3, mai, 1829. dcuxifeme edition (184fi), p. 54. t Jbirinesco, (1. Ueber Veriinderungen der Nerven und des Riicketunarks nach Amputationen ; ein Heitrag zur Nerventrophik. Neurol. Centralbl,, Leipz.. Ikl. xi (18!I2). S. 463 ; 50")'; 504. l. A ii;}o TIIK NKHAors SYS'I'KM. miiiitls ill tilt' (lorsiil rimiciili of t lie cord niHlor/^o piilliolotjiciil ('li:inj,M's iuul lotiillv ilisii|)|it'!ii\ 'I'lic iiudor iild'cs of the cciilriil stniiip ^r.-xliiiillv tiiiniiiisli in iniiiilx'r; in sonic iiistnnccs t li*'v iippciir to vaiiisli iiliiiost totallv, :intl a liir^M> niinilicr of tlut motor cells of the ventral horns dwindle in size (l•'i},^ I HI), and Fl<;. nil. " Sccliiiii llircni^li liuniMn s|iiii;il iurd in llic niiin'v llmi'Miir rrf;ii>n nIkiw iiiK iiii\rUr(l iitnipliv of li^lil li;ilt' dl' ((inl I'dllnwinn luiipiilaliiiii nl' i'i^;lil miiii. I Aflor (i. MMiincscii. Niiiicl. « VnlinlM.. I.ciii/., Mil. \i i ISltL' . S. .'WHi, V\fi. l.i Till' vciiIimI lioni is csin'cinlly Ml ruiiliii'd. as is also tlu' rasciciiliis ciiiK'aliis in all its paiis. Tlii' rascicnliis gracilis * r' is itilait. 'I'lic atrnpli.v of (I14' cells ill fjrniips (I anil h is vrry rviilriil. may after a time be actually lost. The spinal jrani^lion cells do not show gross alterations for some lime after iiotli periplienil or distal libres have degenerated ( l-'riedliindcr and Kranse, Homeii, N'anlair, Marim^sco). a linding which (h'liotcs that their tro|)hic mechanisms ditfer in some way from those which are eoneerned in the nutrition of the cells of the ventral horns. I have thought that this may depend upon the j)ossession liy the spinal ganglion cells of a cellular capsule.* It would he inter- * Another point to l>i' n'moniliorod 111 I'xpiaiiiiiijr tin- ililTiTi'iici' in cfTcrt of ilivision upon tlio poriplioral motor ami si'iisorv ihtvi-s is tlu' faot (lial, if I'lirri'iit iiti'iis of oomiiii'tioii are eovrei't. on sort ion of a motor tiliri'. it is ))i'r- liivps tho (lischnr^o of impulses wliieli is prevonteil, whiii? in tlie case of I In- sensory tihro it is at first tlie reeeption of impulses wliicli is interfered witli. h must not bo forgotten, liowover. tliat even when a pcripiu'ral sensory ■f TIIK NKIKONK AS 'I'lIK INIT. 281 i'stiiig to note if llir synipiillict ic ;,'im;f|ioii (m-IIh, which arc iiIho <'iM'ii|>siilalf study of the central stump of motor nerves soon after the ostahliHlirnent of C ^ 11/ m /{ I iicrvo liiis hci'ii iMil liiriiiij;li, tlio corfcspdiKliii;; cells in llic s|iiiiiii f^iiiitcliii miiy yt'l itoriiiips rccfivr some I'ciitripi'liii iinptil.sos fnnii tlii' visci-ru lliroii^ii tlif niini I'oiiiiiiiiiiicaiiles. * (iiuldcn, K. von. Ocsainineilc unit iiintcrlHssciif Al>inin-'!);{), S. T:M»7. X Darksciicwitscli. L. IJoImt die N'criiiiderinif^on in dem cfMitraleii Absdhnitt ciiics niotorisclicii Nt'rv<>n Ihm Vcrlctzinifi dtvs pcriplitinsii At> schnittes. Nourol. ('.■iitralbl., Leipz., M. .\i (lH!t2),.S, 6r)8-G«8. I, ill I I i . ; I I lli^ .';{'j TIIK NKHVors SVSTKM. the lesion, iiiitl were iildc to sIkiw liy I lu' dfliciitc iiicIImkI of Miii'clii lliiit t'Xlt'iisivc midoiililcd (l(';;('ii('riitiv(' iiroccsscs oc- curred ill tiic lil»rcs.* Ill one ciise, in wliicli llie Tjicinl nerve had been operated upon, Hrejiinan demonstrated eonii)leto dejieneratioii of the fibres of tlie central stump at the twentieth day (Figs. l-tT Jind 148). f Startling as were these re- * I am not sun' hut that tliese results ('(iint' witliiii the prnviiicc of trau- matic ilof^oiu'i'ation, in wliicli cvi-iit they woulii not contradii't llic Wallcrian ), vol. ii. f ! i! I IS '•■ TIIK NKriJdNK AS 'I'llK INIT. 0«><> suits in fiicc dl" tlic \'in\ thai the li'(i|iliic doi-iriiu' ol' Wnllcr li:i(l lirlil swiiy l'<»i" I'diMy yi'iii's, tlicy were t'(li|is('(| liy ot hers, \vlii
  • its, for cNaniple, after excision of a port ion of t he facial nervc! on uni- siiU', ehiUiU'leristic alterations can he denionst rated, eon- sistinj; in tlie main of a rarefaction and finely granular change in tiie Nissl bodies of the cells of the seventh nucleus.* He as- No. 7, ]i. SOH. — Some Xotcs on Ascciiditifj Dof^eiicrntioii (sd-callcd) ami on the Cliaiif^fs in Nerve ("ells ('oiisc(|iifiit Thereon. IJrit. M. .1., liond. (IBlKi), ii, ]ip. 91M-itCl. — Aseemlinj; De^'eneratioii in Mixed Nerves; a ("ritical Sketch with Kxperimental Results. KdinI)., M. .1. (1H!)7). n. s.. i. pp. 40-60. * " Darin, dass dieselbon unter einer feinkiirnigen Umwamlhing rare- ticiren." <: ^ 1 /I I !■ Mi m )iM TIIK NKUVOl'S SYSTKM. HiTlH llitil while I lie clnmjrcs iirc most miii'Kfd iT llit> iiiiiruiil^ iin' killcil jil'irr I'nmi ci^'lil In lil'lt'cn tliivw. to one iiciiiiiiinti'il witli llicin iihcriil'ons iirc n'cof,Mii/.iil»lt' williin tin- fclls of (liiM iMK'lt'Us (IS I'jirit as t wi'iit v-fonr lioiirH after the t>|MM'a(i (M>lls and soinewluil in tlie saiix' form of eells in animals of ililTcrriit s|t(>(ics. l-^en if llif |tcri|tlu'ral nerve is not cnt tliron;;!) I)iit is rendered temporarily ineapalde of fnnetioniii^, the re;iressive alterations «'un he made to appear,ns NissI asserts he hasshown, hv the applieation (d' ehemieal snhstanees (for e\- :i?nple, common sail) to the Iniidv of the I'arial Merv(>, or hy ap- ply inir a temporary lij^atni-e to it. Afl( er these Inive reaehed u maximum (eighteen to twenty-two to thirty days) the appear- ances for a t ime do not alter materially, hnl NissI thinks t hat later the majority of the cells, perhaps tliron^di the formation (d" other nnions, heo;in slowly to recover, so that hy (he liftieth or sixtieth day it may l)e dillicult for the inexperieneed to dis- tinirnish I hem from entirelv heallliv eell,^' ('hariieteristi(^ ehanires in the neiirojilia accompany those fonml ii\ theiu'rve <'ells. Of th«' importance of this nu'thod, which has heen desiij- nated hy NissI as />ir Mrtlimlr i/rr /iriiiKiiiii l\ri:i(tiil* 1 have already sptdxcn in another place. f The method is a very deli- i-ate one — -in fact, the nH)st sensitive as yet introdneed. NissI cantii>ns against drawini:; eonclnsions from its ap|tlicat ion he- fore one has hecome skilled in the iK'cessary techni<|ue. In order to obtain resnits of any value the operations mnst ht> done asei>tieally. and a lon^ and intimate ac(|naintanee with the ap- pearances presented hy tlie ditTerent varieties of cells occnrrinjj^ normally in the reijions nndtM' ■'xainination is ahsolntely es- sential. The procedure has aln>ady heen applied to determine a nnnd)er of complicated relations exist injj within the lu'rve eontres and is full of proniis(> as rejjards the solution of numy intricate tpiestions, ann)nji wliitdi NissI r(>fers with especial hopefulness t involved in the study of the eye-mus(de nuclei. * NissI. l'\ I'l'licr iMii(> iii'iic rnliTsiichuiiirsniothuilt' des Ci'iitnilorpin spoi'ioll ziir l"'('stst(>lliin); lior l.oi'alisatioii dcr NtTvciizi^llni. Vortrji! fjolmlton l>(>i dor Voisainmlmi!; nl' llir lliivr nil iilir ^iilr Al'lrr I'",. [•■Ii'ilnn. Kiirlsilif. ;t'. cxiicriinciilcll fiv.ciiRle Vcriiiidfrunf^iUi dt-r Zcllcii lics Ociilo- Miotoiiiisli.'nis. Forlschr. d. Mod.. MitI., \M. xiv (IHild), No. 6, S. 2()l-22r). + Saiiiivsky, S. Nrvritc (•xprTiiiinitiilt' piir conipn'ssioii (^1 h'-simis (;on- sc'ciitivfs (ics ('cnlri's iiervoux. Ciiiiipt. rciiil. Soe. dc iiiol., I'ar. (INillj), 10. s., t. iii, pp. 855-358. X i^iciil, A. l^'ticr ihe ("entni licr Splancluuc!!. Wicii. I TIIK \i:i;\()lS SVSTKM. thinks 111' liiis liccii ;il)lc liy tliis mctlKiil to decide jis to tlie ])or- tioiis oi" I he iiuch'ns of t he oeidoiiiotoriiis respectively coiicei'iied ^- ' ^'^afe:.!6!v.-.ii!.,i :^--' ■■■■■• ■.\ ^^'"-"oi^i^k^'^' "■*"'-',"':\ y A Fl(i. 150. — Four iicrvc cells f'nuii tlif iiiicliiis iicrvi t'aciulis (if ii nililiit tit'tccii days iit'tcr sciti III of tlic III rvf itmt. Dr.iwiiif; iiiaiU' Iripiii tiiic nl' ,1. Kilaufitr's prcparatiiitis. in the innervation of the extrinsic and intrinsic muscles of the eyeball. According; to him, in the rahhit the four external eye muscles supplied by the oculomotorius nerve are governed by the t;anTii (\'i'.l(iiiuit(ii'iiis vt'rsoi'f^ti'ii Mtiskolii dcs Aiigcs. Arch. f. Opluh., Leip/. (1897). \V\. Ixiii. W. Ablli.. S. 4yi-.j'ir). TIIK NKriJoNR AS TIIK rXIT, |)i'(i.\iiii:il portions of the iiuclriis. .1. I'lrliiniicr is al prcsfiil cii- <:;ii;('(l with iiir in tlic study of tiic spinal cords of animals from whii'li pieces of ncrvi's supplyini;' nuisclcs, and in some ii,- stanci's the muscles tlicnisclvcs, have hccn excised; tlieri'sults of these invest illations will he published later. In Fiir. loHai'c shown SOUK' cells from the nucleus nei'vi facialis lifteeii days after section of the facial iiefve. 'I'he\ may lie com])ared with i( of Fiji;. 14!t, which re])ivsents a nonnal motor ci'll. As to the elTects U]io)i the cell hody induced hy injury to ;, portion of tlu' teriuiiuiLs of the collaterals of a given axoiu", w. have as vet lu) evidence. n a Kk;. ir>l. N'l'iilnil lupi-ii cells ;' .111 tlic spinal curd ol' a cast' (if iiiiilliiilr iiruiitis. I Alter I'.allil and Diilil.' nji. ((dls slaincd willi iiiddcanniii : <■. irll slaincti with lin'nialux.vliii ; (/, ctdl slai'iid li.v Nissl's niclliod. 'I'lic alliialiuns in tlic ( ludinalic .snlistanci' and llii' ilisldralimi id' llii' iiin Itiis arc wc II sli iwn. Kx])erinu'nts such as the t'ore<>-()in,u' place certain diseases — for example, tlu' so-called ])eripheral lU'uritis— beur :s in an entii'ely lu'w lii,'ht, for it is obvious that even if the ; .d i)ro- cess be conliiu'd at first exclusively to distal portions of the axoncs (tiio lesion, when of the nature of a focal tu'crosis, is \ 238 THE NERVOUS SYSTEM. usually dependent upon poisons circuliitin^ in tlie blood), it does not remain localized in them, and, as we have seen, injury to an axone leads t. Xtrve (ill iroin (•cniirMi experienced may easily be led to cortex of (loK. It sliows iiltci'iilions , ., ii i • i n t (liicily ill the (liiid rites tiinicd to- describe pathologiciil huduigs Wiird a throiiihosed vessel. (AHer .^1, ,.,.,. j,, ••(.jilitv iioin' evi'^t I Monti. Areh. ital.de l.iol.,t.x.\iv.) WIRIC, in 1 1 aillV , UOUC t MSt. 1 must confess tlitit I nm very skejiticiil of accepting as fiicts the statements in any publica- tion of work biised on XissFs niethods where I am not sure thiit the results have been controlled by an investigtitor of experience. Unfortunately, tissues fixed for staining by .Xissl's method ill alcohol or corrosive-subliniiite solutions tire not suitiible for staining by the method of Weigert or by that of .Mtirchi. * Riillet. (J., et A. Dill 11. Siir nil ens iW iMilyiieurKc iivcp lesions mediil- lairt's. Hull, el inein. Sue. med. d. lioi.. de I'ar., ;{ s., t. xii (ll^i'-Tij, 1>I>. H1H-H2I. THK NEURONE AS THE TNIT. 239 MariJiii * has tried to obviate tliis difficulty. His fixiuff rnix- tuir (formol and chromic acid) permits of staining of the tissues by the methods of Weigert, Xissl, and Van (iieson. The Xissl j)repara- tions are not, liowever, so beautiful as those prepared in tlie orthodox way. As regards the effects on tiio whole neurone result- ing from injury to its den- drites we have much less detlnite information. Leav- ing out of consideration in- juries to peripheral sensory nerve fibres, which, as we have seeTi, corres])ond in tiieir end)ryol()gic.d origin to dendrites, and which, as 1 shall point out a little Fm. l ■'):{. Larger pyramidal tflls fnnii ilic , , ., , „ . . second laviT 1)1' tile fcn'l)ral cortex slmw- later, thou-h conforming m in^ advance.! stages of d.Kciuration lul- their phvsj. ..gical behavior, l"win^Micin ,M,isoMinK..ir.mrteen li.mrs' 1 - '^ ' duration. I lie < tils have lost tlic an;.'n- iit least so far as the con- 'i'l'ty of tiuir <(>ntonrs. (After Jl. ,). , . „ ... IJerklev. .lolins Hopkins llosp. Uep.. dnction of nerve impulses is vol. vi, I'l. .\ii.; concerned, nither to what is genenilly true of detidrites than of axones, are nevertheless his- tologically indisputtibly tixones, we have as dtita in this connec- tion only the observations of Monti f and Berkley.^ These ol)- servers, employing the silver method of (Jolgi, the former in cases of iiumitionand experimental cerebral embolism (Fig. l-Vi), the latter in sevend varieties of intoxication (Fig. 1515) and in *Miiriiia, A. Kino Fixiitioiisnietliodo. boi woIcIilt sowohl die Nisisrsche Nervoiizelle als die Wci^jrcrl'schc .Marksclieiilefiirhuiifj geliiist. Neurolof;. (Jcntraihl., lieipz.. Ikl. xvi (lISDT). S. HiG. , f All cpitoine of t lie work nf Italian iiivesti)j;ator.'i with (i()lj,'i's inetlKid with rcf^afil to iiatli(il(>f,Mcal alterations in nerve cells is to ho found in tiie eoinprelu'iisive review of ('. Saeerdotti. in Ijiibarsch-dstertajf's Mi'f^eliiiisse der allgem. I'atholojjie ii. patii. Anat. des Mensciien ii. der Tiiiere. Zweiter .lallrJ:an^^ IHjm. Wieshadeii (1H!»7). S. 7!t!»-800. I IJerkley, II. .1. Studies on tlie licsions produced liy the Action of Cer- tain Poisons on the Cortical Nerve Cell. Johns Hopkins IIosp, Uep.. I5alt., vol. vi (1M!(T). fasc. i. pp. 1-88. f * : m II It i -ri W\ /i (' , I' I 'J4() TlIK NKHVOUS SYSTEM. tcniiiiuil (Iciiiciitiii (Fiir. 1'">1^), liiivc found tluit uiidor oortniii cir- cuiii.sliiiici's till' (.'arlic'sl k'sions which ijppcuri'd were those ull'cct- injjf thi' dendrites. Those showcil varicosities ;iiid distortion pheiiomenii willi loss of tiie ii'cinniidcs and Unci' side hriUKdu's; ^^^^^^^^^Er^^^^HH • ffl ■ M- I^H » • ■ ^ » ^^1 ' W. ' ■ >. ^^1 ■■* I -• . • H ,%' ■ .J * H *^H <^^^I^^^^^H ^ -' ^L ^^^^^H ''^^^^■^^^H ^H -• ' • ^ « '• ^^^H ^^^^1 '■ '*•. ^H^^H ' M ^^H^^l i , . ••.^: ■ * 1 * HH f ..i I *',-.;i ,- ^1 ' » . PI I^^Pr ^^1 ^^H « i H r ^■^ ^^1 -'S ^ ' ^^^1 ^^^^■r y^ ^^^H A 1 wty^ ■ U 1 (t. h. Flii. lot. St roiii; apical (Iciidiitcs nf ipyiMiiiidiil (ills rnuii the luiiiiaii (■criliral ciirlcx. ((, iiipiiumI clciidritc ; A. (Iciidiitc rniiii a iiyraiiiidal 42 TIIH NHKVors SYSTEM. Tliis l)ri)i^'s us to the iitilizjitioii of cxpcriiiiciitiiUy pfodiicod sc'coiidiiry (loj^t'iicnitioiis, hy inciiiis of wliicli iiiiportaiit coiiti'i- hutioiis liavi' Ix'cii iind iirc Ix'iuif iiuidc to tlic iinatoniy of the central nervous system. No matter \\ liat nerve cell or ^'roup of nerve (!ells is destroyed, wlietlier in the s|)inal cord, in the medulla, in the thalamus, or in the cerebral cortex, whether belonging to the projection systems or to the association sys- a. A. & C e •■'■■S^'^':/'"jik.X'-' '^^ *- V'- ' *>■». '-■-.■ .'•*--■ •:/ I ' ,--1 ?«i* ^ I'ki. I.').'). KrriiiiMl section tlirip|i;,'li ll'c incsciiccjilialuii sliiiwiii^ vascular supply. Al'tcrS. Sliiiiiaiiiiira. Neurol. ( Viitrallil. I,ci|(/., I!cl. xiii * isitl , S. 77.'), I'"ii;.4.i ti. miclciis cipipinis (|iiavious than that t-ertaiu ;^rouj)s of neurones in a {fiven individual are more susceptil)le than others to a j,nven toxic a'fent ; more than this, the same <,''roup of nerve cells in two indi- viduals may react very ditl'oiH'utly to similar doses of the same poison. Our daily experience with the etl'ects of alcohol, cottee, tea, and certain ana'sthetics upon ditl'erent individuals and upon our- selves under dillei-ent circumstances are of interest in this connec- tion. The toxiaes of .syphili.s, although we are entirely ignorant as to iiieir nature, show a decided ])reference for certain parts of the cerebral cortex, other areas beiny less often att'ected. llampe's ob- servations conceiMiinj,'- the diU'erences in the psychi<' distur]»ances followinf,'' carbon-l)isulphide i)oisoninK' in ditl'erent individuals are very convincing' in this re{»'ard, as are also the careful psycho-jjliar- macoloofical investigations of Hoch and KraejM'lin * concerninj,'' the catleine and ethereal oils in samples of tea. It is Flechsig's idea that these variations in vulnerability of diti'erent g^roups of neu- rones, and of the ditl'erent jjortions of the individual neurones, an^ to be traced back in larye part to develoi)mental conditions, a suf,''- gestion which is highly i)Iausible in view of the evidence that can be brought forward in its favor. The answers to the questions which we have fornmlated concerning the events occurring;; in the various component j)arts wlien cut off from the main body of the neurone, and tlie effects of lesions of individual portions of the neurone upon tlie neu- rone as a whole, are, of ne<.'essity, as yet very incomjilete. Suf- ficient evidence, however, is at hand to render clear the fact that the neurone as a icltoh' is a trophic unit, and that any attempt to locate the trophic function exclusively in any one portion of it must assuredly fail. We have seen that we possess reliable observations which all favor the view that injury to any part of it also affects to a greater or less extent the remainder of the neurone, and that no portion of a neurone is capable of existence for any great length of time after the severance of its ♦ Tloch, A., u. E. Kraojii'liu. I'obcr die Wirkuiis dcr Tlu'obi'stjuKltlicile aiif k()rpi'rli('lii' uud gcistige Arbeit. Kraepelin's Psyciiolog. Artuiiteii, Bd. i (1H!)5), H. 2-3, S. ;57H-4H8. THK XKURONH AS TIIH TNIT. 2io coiiiu'c^tiou witl) the rest of tlic nerve unit. And after all, when one thinks of it, tliis is not so very astonishinj^ ; indeed, it is rather a matter of surprise that the fact should have been ques- tioned, after the knowledge had onee been gained that a neu- rone as a whole represeiitsa single cell, for we have long known that even in such i)resuniably little differentiated protoplasm as that jiossessed i)y an anueba, an injury (for exam])le, with silver nitrate) to one portion of the cell body is speedily answered by phenomena which concern the whole of the unicellular organism. How little likely that a nerve cell, the protoplasm of which n'presents the highest example of differentiation along the liiu's of irritability with which we are acfjuainted, should i'emain uninHuenced by irritation or destruction of one of its integral jiarts ! .Many facts juight be added in connection with regeneration (if nerve fibres and nerve cells which have more or less bearing upon the trophic functions of the neurones. On the regenera- tion of lU'rve fibres an immense amount of work has been done,* some very im])ortant contributions having l)een made by inves- tigators in this country, especially by Howell and Huber.t It has long l)een known that on suitable apposition of the ends of a divided motor or sensory nerve, the axones of a central stump may grow out again to the periphery iind function nuiy again return. In the event of the rc-establislunent of coniu'ction and function, the regressive alterations which begin to apjjcar in the central portions of the neurone almost immediately after section (Nissl) gradually give place again to the uornud ap- pcaraiu'cs. The investigations of I'acr, Dawson, and Marshall, carried on under the direction of \V. H. Howell ( !S!lT), speak in favor of the regeneration of the central axones of peripheral sensory neurontss in the dorsal funiculi of the cord after experi- * ("oiiiptu'e the excellent review and i-rituiue of the bil)liogniphy up to 1895 liy II. Stroi'lie. Die ali^jeiiieiiie lIisloloj,'ie der degeiierativen uiid regeiieni- I ivcn Proecsse iin ceiitralep. mid jicripliorcn Nerveiisystciii nadi deu nciiotcn Forsehmigen. Zusaniiiieiit'nssendes licfenit. Cciitrallil. !'. allg. Path. ii. liatli. Anat.. .Fena. Hd. vi (IHir)). S. H4!MK)0. + lloweli. W. II.. and Iliilier, G. ('. A Pliysiohtgk'al, Histological, and Clinical Study of the Degeneration and Kcgeneration in Peripheral Xcrve Filiresafter Severanee of tlieirConnections witii the Xerve Centres. .T. Pliys- ioi.. Candiridge. vol. xiii (ISiri), pp. ;i:).")-4(H!, and vol. xiv (180:!), p. 1 ; also lliiber, (i. C. A Study of the Operative Treatment for Loss of Xerve Sub- stiinee in Periiilieral Xerves. J. Mor|)Iiol.. Most., vol. xi (IHito), pp. 6'29--740, '•U * /i I : i' i>4»; TIIK XKKVors SVSTKM. i iiii'iitiil lesion of ii (lorsiil root Ijutwui'ii I lie <;iiii^lioii spiiiiilc and the spinal cord.* Kcf^ononitioii of severed nerve lilircK within the spinal cord and I)rain is, nnfortnn;itely, very ninch less cnniplete than in pe- ripheral re;;ions. Whether a nerve cell once entirely destroyed can have its place ade(|nately (llled hy one formed hy division from another nerve cell is a (|Uestion of vital interest. Tiio reseurches of Tiji^^es, .Mondino, Coi-n, Cattani, and I'opolf are of importan''e in this connection. 'IMie newspapers have recently contained the most e.\a<,'f I'isa, althon<;h this investij^ator also asserts that he has (lenionstratc(l the possibility of a report the prevalent view that in adult animals ,iLtanj,di()n cells once di'stroyed arc not re a I'aljlation coniph'ti' dcs lolics occipitaiix. Coinpt. ivnd. Sou. l)iol,. Scptcnibcr 1(>, 189.') ; also in Coinpt. rend. Acad. d. sci.. I'ar. (1895), cxxi. 44.'"»-44T; and in Arcii dc piiysidj. norm, ct patli., I'ar. (1897), T) s., t. ix, pp. '29-4;{, 1 |)1. I Tcdcsclii, A. Anatomiscii-patiiolofrisclio und experinipntclle I'nti-i- snchnngcn ilhcr dii- {{cj^MMieralion dos N'crvcn;,M'woh('s. Vorl. ]\!iltli. Ccn- trallil. r.ally:. I'atli. u. i)atli. .\nal...Icinv. lid. vii (lS9(')).S.449-4r)l ; also Anato- iniscli-oxpeWnicntoller Boilray zuni Stndicn dor Rogonoralion dps (U'wobf di's (VntralniM'vonsystcms. Moitr. z. palli. .Anat.u. z. allj;. I'alli., Jena, 189T, xxi, 4;{-Tv>. ;i |ii. * Tirclli. V. Dei propo.ssi ripiirativi nel ganifiio intervcrtpbrak'. .Ann.di frcniatr. <■ sc. aflini, Torino, vol. v (189')). pp. 9-'2(l ; also Transl. in Arcli. it.il. dc liiol., Turin, t. xxiii (189r)-'96). pf). :!01-:!l(i. I ^foiiti, A., ct Fie.schi, D. Snr la guprison iIps blossures des ganglions sytTipatliicpip. Arch. ilal. dp Kiol., Turin, t. xxiv (189r)-'9C), pp. 4()l-4i:{. Iioweve Loci), ii in I'Ui. |,->(|.— iiiii'dili mix till' process o the histo; Of th( that tiu'y neurones, /'/■fori mi I liave cliaracteri Walleri: our miiK l>ortioii.s IK) inteiiti lU'urone J^iich an i( the Olio |>.ii-t playc ill the nut t'licli has the iion-tiK ent from We hai jdienonicM; «liall retur tions to th * Flexn.T •orva and il 'Morpliol.. I!,, TIIK NKrUOXK AS TIIK I'NIT. '2Vi however, is I'lilly estiildislied ; witness the experiiiieiits of Hoiix, Loel), iiiul otliers. Klexiier hiis recently stndieil witli eare thu V "* Q^^••^'v'^ •r t^ V- © h'l(.. l.")((. -( iiryiicinilic tiymcs in nerve ci'lls in ln'iiin nf iId^ llinc <1m.vs iiflcr inlrciilni'lion ul' I'mriKn licidy. ( Alter Tt'dcsclii. > l''i\utiT-'i)8). pp. :{:!:-:{4(;. :rT| Si A A Li IMAGE EVALUATION TEST TARGET (MT-S) k // O / ^ I 1.0 I.I 11.25 |5. |3.2 I «. S120 U IIIIII.6 V <^ A '<^. e. ^ Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, N.Y. 14580 (716) 872-4503 "^ \^' ^reni-e of an excitation from one neurone to another — The " neu- rone-threshold " — Importance of proper a:>() TIIK NKKVors SYSTKM. thfiiisi'lves, the solution of any one ol" wliich would l)iMnossible motor axones of the dorsal roots) are intact, and the memory traces of previous movements must be believed to still exist, movements of the liml)s innervated by the corresponding seg- ments of the spinal cord, those , hich are com])licate(l as well as many which are (piite simple, are only very inaccurately carrit'd out. The continuity of the nerve excitations can therefore scarcely he insisted upon too forcibly, and I am in- clined to agree fully with (jioldscdieider when he says, '• Ks herrscht eine zeitliche ("ontinuitiit von Krregungen in alien Bahnen des Xervensystems.'''' As Donaldson.* writing in this connection, beautifidly puts it: " In this picturing the entire ■! ; "' i: M /i nm.- * Op. n't., p. '284. 9 fill I I'::il ih '. 252 TIIK NERVOUS SYSTEM. nervous system us a sensitive nicchanisni, it is evident that it must resi)ontl to tlie surrounding stimuli as does the water of a hike to the hreeze ; and such is the rehition between the central system and its environment that the breeze is always blowing and the waves of change always chasing one another amodg the responsive elements. If t''ere are no waves, then the cells are dead. The breeze still blows, but it falls on a frozen surface, on cells chilled and rigid beyond the power of response." The influence of the arrival or non-arrival of external stimuli to the ni'urones upon their trophic and nervous functions will be referred to a little later. If among external stimuli we class not simply those outside the body, in which event a very minute fraction of the whole number of neurones would be directly accessible to external stimuli, but all those external to a given neurone, including those arriving through the lymph which bathes it, or l)y means of the ])rocesses of other neurones which enter into relations of conduction with it, wc shall come to the conclusion that the limits of genuine spontaneity of action on the part of neurones are very narrow ; indeed, sonu^ authors would deny its existence altogether. Von Lenhossi'k, for example, says: "Man darf den Satz wolil als gesichert betraclitcn, dass es keine Ncrvenzcllc giel)t, die ihre Merven- wirkungen aus s' ii selbst heraus, ohne aeussere Impulse, spoji- tun cntfalten konnte." The reflex actiinis are very obviously dependent upon external influences, as are also the instiju-tive reactions, and what we call volitional movements are, when analyzed, apparently only reactions to eAternal influences modi- fied by memories. We must not lose sight of the fact, how- ever, that there may be periods of considerable length inter- vening between the arrival of the external influence and the discharge of energy whicli it determines or lielps to determine, just as we know that the springs of conduct often lie far re- moved from immediate acts. And it is just here that the laws bearing upon the summation of stimuli * assume an csiiecial interest, although they must be passed by now without dis- cussion. * Cf. Du Rois-Iieytnond. Uobor die Ansl<")sunji von Rofloxbcwcgungen (hirch pine Stinunc scliwaclu'r Koi/o, 18H0; also tlie review of tliis subject by S. Exiier. I'^ntwurf zu einor physiologischen isriiliining der psychisehen T'^rselicinungen 1 Tiieil, I.ei|iz. u. Wicn. Svo (1S94), Cap. ii, S. 49. THE neuronf: as thk rxiT. 253 Of the pliysiology of tlic transference of an excitation from one neurone to another, a word may be in phiee. All our knowledge of sensation goes to indicate that a certain minimal amount of stimulation is necessary to call forth a reaction ; for exam])le, to stimulate a pressure point in the skin u certain amount of pressure, say from a hair, is required to elicit the sensation of touch. Any pressure less in amount will not suf- fice. That is to say, the touch point has a "threshold value."* In the same way there are threshold values for the various cold points,! warm p.)ints, and pain points, and in connection with the special sense organs much work has been done upon the spe- cial threshold stimuli which will call forth sensations of light, smell, sound, and taste. It is obvious, if t)ie neurone doctrine be true, that for the spreading of an impulse or excitation tlirough the nervous system one neurone must act as the exci- tant upon the neurone or neurones beyond it whi(!h stand in conduction relation with it. It seems highly probable, there- fore, that each neurone has a special threshold value, (iold- scheider,! in a brilliant essay recently published, has defined the "neurone threshold" {Xeuronxrhivi'lle) to be the degi-ee of ex- citation of a neurone which just suffices to call forth a fruitful excitation in a neurone with which it is in contact ; that is, that sutticient to call forth a sensation, a movement, etc. If this view be correct, the resistance in the passage of the excitation from neurone to neurone would, (ioldscheider believes, lie at the point of contact or of concrescence of the neurones. A series of new problems are opened nj) by this suggestion, not only with regard to the easier propagation of impulses in habit- ual nerve processes {Balututui) and with regard to the phe- nomena of inhi])ition {Ifcnumaiff), but also with regard to the therapy of nervous diseases, especially the explanation of phys- ti'ia t.. :-l| /I ■ > ■ ^ n * Cf. V. Frey, M. I'ntersueluingen iil)L-.- die Siiiiiesfunctionen dtT inenschlichen Ilaut. Erste Abhandlung : Druckcinpfindiing und Schinerz. Abhaudl. d. niath.-pliys. CI. d. K. Siichs. Gesellsch. d. Wissensch., Bd. xxiii (1896), No. 3, S. 168-260. t Harker, L. F. Ueher eiiien Fall von einseitiger, umschrieberier und clcktivor sensibler liiihinung. Deutsche Ztsehr. f. Nervenh., Leipz., Bd. viii (lH0r)-'96). S. 848-^58. Also Traiisl. in J. Expor. 31., Bait., vol. i (1896), pp. ;J48-860. X Goldsehoidpr. A. Die Bedeutung der Reize fiir Pathologic und The- rapie ini Liehte der Neuronlehre. Leipz. (1898), Svo, S. 1-88. I 254 TllK NEIiVOUS SVSTK.M. ical tlicrapcutic inctlKMls like iiiiissalete. Is it not much more likely that in the gradual |)rocess of development and modification peripheral and central organs have been correlatively differentiated ? We can not think that the various modifications of apparatus mediating between the external [ihysical influences and the most jieripheral [tor- tious of the sensory neurones of different kinds represent acci- dental structures whiidi have no physiological import, nor can we imagine that were the central jirojection fields in the cere- bral cortex, at which the sensory impulses arrive from the dif- ferent parts of the periphery, »»f lU) specific signiticaiuie for the origin of the different sensations, they would present for the * For a clear and comploto nccoimt of tlio doctriiii' liic rciidcr is idi irtMl to A. Goldsc'lii'ider's articli': Die Lehre von den specifischen Energieeii der SiiiiH'snervcn, I5erlin, ISHl. i,. 'li 'j; /I >ntW 'i| ;lli{|i| 2r)»; TIIM NKUV(HS SYSTKM. (lilTcrcnt .sciisiitioiis so iibsoliitcly spfcific a structure* 'Flic piitli()l()j,n<'iil cast's aj^aiii, in \vliiv tlic jippiircnt cxist- vuw of nicclianistns for cxclutlin",' it from the ilircct path of the fiirrcnt. A prr;,'nanl t-xainplc (dlorcd was the arran/^'cnicnt ill tlic spinal j^'aii^'lioii cell. l''or a lon«,' liiiii' it was licld l)y many lliat the 'I'-sliap^d process wliicli l)n»ii<,'ht the pt-riplicral into a direct line with the central axoiie was for the purpose of ciittiiif^ olT the cell hody from the conduction path, 'i'liis idea was lu'ifatived hy the demonstration of Wiiiidl * of a delay in the passajj;e of the i;ii|tiilNe correspoiidin;,' to its |iassaj.'e t hroii;;h the spinal }xaiijj;lion of 0.()():{ «tf a second, a result which has heeii conliriiied and extended hy the evieriiiieiits of (iiid and .losepii u|)oii lhevaii wir idles ziisaiiimcii, so scheint, wic die SiK'lieii jclzt litigcii, (lie VVagschale doch in hohoin Grade zu (Juiistcn dcr iicrvIVscii Natur dcr Dendriteu sieli zii iiPigL-n." IbiiKlbucli dcr (icwcbL'lclire, Hd. ii, S. IK!. /i "Ti : t IN » i I li!' 1 I liC)!) TlIK NKIJVors SYSTKM. ])liysi(ilo withtlic plexus of di'iidrites in that sit nation. I thcolfactory hulh, however, and in Ammoirs horn and the fuscia deutata, there are dendrites which appear to have no direct relations to the terminals of collaterals or axones of other lU'urones. At anv rate, su(di relations have not yet been ju'oved. Kven von Lenhossek, who along with van (ielnuditen ami Kamon y Cajal is one of the stroni!., l,,-i|)/. (ISOO), S. 4(1!)- 177. 'I'lIK NKllfoNK AS TIIK I NIT -»il Waltt'f,* that tlic lil)r('s mphat ieally (I) that the dendrites can assume the conduction of nerve impulses and {'i) tliat the transference of nerve impulses from one neurone tt» another can take jtlace directly from fibre to fibre, a direct influence of cell body uiioii libres or of fibres upon cell bodies not beiiij; 'ssential The existence of anatomical relations which render neces- sary the assumption of a i'oiidiictiii, IM. i, h'in. t. i In the cxteriiiil layer ,( ;iie re|)resente(l the teiiiiinals ol' the lilires oC fetinal origin ; in the layer It are shown several nerve cells ol' the iniildle /.one of the optic lohe ; fi\ zone of peripheral nerve tihrcs ; n and h. superficial aihorizalions ; (•and (/, deep arhori/.ations ; c, reclanf;ir hy a horizontal arhorization at the level ol' the deep retinal arhorization. The axone arises from the peripheral dendrite and runs throu};h the middle ia.ycr, ^iviuK olf numerous collaterals, ('. ':c. ■ > J J 1 eut estal)lisli('(l. That it is one niethod of transference is cer- tain ; but that tliere are others, for e.xaniph', throuffh direct i' f I : [: 204 TlIK NHUVOrs SYSTKM. contact or concreaconco of iixoin! terminals witli the protc])lasm of tlu! cell body, all grant. It may Itc uoitli while to i)oint out Just licrc a certain fallacy of {jencrali/atiori (o wliicli. curiously ('iiouj^!i. attcutiou appears not to have been called. Kvidence has Iwcn adduced wiiich demonstrates indubitably that in certain parts '" the nervous system the anatomical relations are such that a cond;'ctin<^ function for the dendrites must be admitted. This proof was brou{,''ht forward as one of the means of demon.stratinj;' the nervous function of the dendrites. But some writers appear to take it for granted as a necessary secpience that dendrites for wliicli no sudi aiuitomical rehitions are demonstralde pos.se.ss no nerve function. If this were souml reasoning, we should have to a.ssume that the transference of impulses from one neurone to anotiier made up the sum total of the nervous functions, an absurdity too obvious to need further discus- sion. We have not the right to draw our deductions from any one factor to tlie exclusion of all other coexisting intluences. It is sui-ely easy to conceive of a particii)ation of the dendrites in the nerve functions of the neurone, even if they stand in lu) direct rela- tion either of receiving or discharging to another neurone or set of neurone.s. Indeed, granted that one ])ortion of a single cell, as we believe a whole neurone to be, po--M•s^ s nerv(^ fuiuition, the onus of proof upon the (pie.stion of the ature of another portion of this cell — for example, the dendrites lies with those who deny the nervous function, not with those w maintain it. Now that the cell body of the neurone is known to possess nerve function, the fact that the a.xone often comes off from a dendrite instead of from the cell body is further evidence in favor of the identity or at least similarity of function of cell body and dendrites. This conclusion would agree strikingly with the morphological resemblances revealed by the method of Nissl. Further, if anaxo'ies are to be regarded as nerve cells, as seems almost certain, the dendrites must surely possess nerve function. That the a.xones are concerned in the nerve function of the neurone has, so far as I know, never been (|uestione(l. It is generally believed that in the conduction of the excitations there can be no transference from oiu^ jieurone to another except in those parts in which the myelin sheath is not present — that is, for the majority of neurones, so far as the axone is concerned, only in the region of its terminals and possibly in the short Jion-meduUated portion immediately adjacent to the t llli THE NKUHONE AS TIIK IXIT, 2r.r. ncrvo cell. This statciiicnt is i>(|Uiillv true of tin- colliitc'rals, for, as Flcclisig * has siiowii, these bniiiciu's, at least in the cerebral oortex, are, like tlie iiiiiiii axones, jirovidiMl with medullary sheaths. We have iiiduhitahle evidence, too, that the majority, if not all, of the c(*Ilaterals of the dorsal root fibres within the spinal cord are niedullated. The side iibrils of (iol^i are non-medidlated, and from the studies of von Len- hossek, Apathy, Held, and iieihe ma\ probably be important a^'ents in the transference of itn|»idses from neurone to neuroiu-. The relation in which the side Iibrils staiitl to the neuropilum in invertebrates has already been referred to. /I * Flwlisifj, P. Ufbcr cine ni'ue Fiirbiuiysiiictlitxle dos (iciitralt'ii Xcrvi'ii- systems imd dcrcii iM-f^clmissi' l)czii};licli dcs Zusuniiiu'iilitDigcs von (ian- {^licnzellon iind Xcrvi'niii.sern. Arch. f. Anat. ii. I'hysiul.. Lcijiz., I'liysiol. Abtli. (18H!)), S. .%?. U :]■■' '.! < * I m >itm 1 I ■ I lim^ CIIAI'TKR XMIl. ox THE DIRKCTIOV OF rONniCTIOX IN Til K XF^l'UOXKS .VXD TlIK TIIKOKY OK TIIKIK DYXAMIC POLAKITY. Oiroptioii followt'il l)y iicrvc itn|iuls(s in their ]iass«i^i' tliniuj,'li iiciiniiics — CflluliiR'tiii iiiul t'ol!ulifiij,'.'il coiKliiftioii — 'I'licory n in der Tichre von der Ein- riehtnng des sensiblen Nervensystenis. Hiol. Untersiich.. Stockholm, n. F., Bd. iv, 1893. 26G I 1 ''*;u •i 'I,. TIIK NKITRON'K AS TIIK U.VIT. 207 should serve for the rcccj^tion of stiimili.* Tlu' uctiiul proof of (•('lliiIi|H'tiil contlnctioM in (Iciulritcs is cstiiblislit'd l)y tiie obser- vations ])reviously mentioned, wiiicli demonstrate tlieir con- duct in■' early all writers have aed I. sendiiif; one hninch into a sensory root. viously, the direction of the condtiction of the sensory impulses in the pcriphi'ml axone is cellulipettd ; in the central iixoiie, cellulifugal. Those who hiive committed themselves to the doctrine of universal celliilifugiil conduction in axoiu's btive denied !hat the axis cylinder of the peripheral sensory nerve fibres is i*' ally an iixone, assuming it to be rather dendritic in II TIIK NK IfONK AS TIIM INIT. Fifi. KiO. — Spinal curd of Min|iliioMis. i Al'trr Hct/.iiis. i mi. inidiaii linr ; iih-, (iiilcr aM!,'lr ciCspiiiiil ronl ; s, sriisory root. A liitlicr laru*' iimltipolar rcll is shown, till' axonr ol' wliiili enters intii a sensory rout. the iii'riplicnil fibro is, iisu ruU", longer tliaii tluMicntral ; for thu cochU'iir iind vpstibultir giinglia the pcriphcnil tihrc is the short(!r, ami luTo the pnxH'Ss passing to the periphery is of smaller ealil)re than that of the eentnil iihre. I tiik(! it tluit we niust a(!kno\vle(lgo that, though enihr^'ologieally a dendrite, the periph- eral sensory fibre in the adnit is histologically' an axone, and the passage of impulses from the periphery to the centres must bo granted as tin exanij)le of (H^llulipetal conduction in an axone. In amphioxus, an animal which p()ssesses no spinal ganglia, Retzius f has shown that the sensory impulses are re(!eived !)y the telodendriojis of axones and (conveyed along axonos eellnlip- etally to the nerve centres, a form of sensory apparatus very commonly met with in invertebrates. In amphioxus two varie- ties of cells send axoiu-s into the sensory roots, bipolar cells (Fig. 150, n z') and multipolar (sells (Fig. KiO) (Smirnow, Ret- zius, von Lenhossek). * Tlip sufjfil'cst ion that (ho poriplicriil sensory filtro is a dentlrile was, I bi'liovo. first mailc by l{«inoii y Cajal. in IHHi), in ati (irticlc entitled Cdii- nexion f^eiionil de los eloinontos nerviosos. which uppcanMl in La i licinii practicn, ^bidriii, in ()(flol)or of tliat year. t Uotziiis, G. Ziir Kenntniss (it-s eontraleii Ncrvensysteins von Amphi- oxus lanceoiatus. IJioi. llntcrsui!!!.. Sloekholni, n. F., Htl. ii (1891), p. 2!). I ; I i '{ i .1 ; I ! ( ;i!ili // l: ., ti m: i i^4 270 TIIK NEHVOUS SVSTKM. t ' II k The fiift that the optic nerve ('(Hitains axones whoso rolls of oril>it stiiiiicd l),v tlif cliroiin-silvfr iiictliod. /(, liiH' plfxiis fornicd of (iol«i's ,siun side lil)rils, <■. ( Al'tcr M. voii Lciiliossrk, l)cr fciiicrc I{iHi d«'» NiTvi'iisysU'ins. etc., II Aiill., IWtr), S. 257. Fifi. :W. ' tion must be granted, for tliese fibrils are limited to no singU' portion of the neurone. Moreover, since the same fibril cau sometimes be followed runniTig cellulipetally in one branch of a dendrite and eellulit'ugally in another branch of the same den- drite (Hethe), it is obvious that, if the fibril conducts, the den- drites must carry both cellulipetal and cellulifugal impulses. A most interesting and difficult experiment performed by Bethe* must here be referred to. This inves^i'jator, working at Naples in November, 1S!)(>, isohited the neuropil of the sec- ond antenna of Carcinus — in other words, he removed the gan- glion cells of the neurones supplying the antenna, but left their processes and side branches. He proved that, even in the ab- * Bethe, A. Das Cciitralnervensystcm von Carcinus Maenas. Ein anatoinisch-physiologisolier Versucli. I. Tlieil, 2. Mittheiluiig. Arch. f. inikr. Auat., Bonn, Hd. 1. S. 589-639. .,^«<. •• ' •ni ■I ■ 111 , 1;! A % ftl 'I t' 273 TIIK NMHVOllS SVSTKM. «nii<'<« of the pcrikiirvoiis of (he iiciiroiit's, llcxinii aiul cxtt'iirtion ciiii be rt'llcxly prodiict'd — iippaiciilly aii iil)soliitt' (Icinoiirttru- tioii tlijit lu'uroiics cjiii tctiiporiirily contimic to I'litictiou in tlio entire! iibscncc of tiicir cell bodies. In a still Inter article,* as a result of his studies of the primitive tihrils (Apathy), IJeIhe eon- eludes that the explanation of nis fundamental reflex experinu'iit irt to 1)0 found in the relations which the lihrils hear to the mech- anism. Tlieso ndations are illustrated in Vi^. Itl".*. When Bet ho I'm. Iti^.— Si'lii'iiiiilic (IniwiiiK tci illiislrulc tlic com'sc of tlic |iriinitivc lihrils of till' ri'ccptivi' iiiid iiiotof clciiiciits of the sccoiiil aiitciiiiii of i 'iO'ciiiiis Macims. I Aflir A. iicllii', Anil. f. iiiikr. .Viml., Hoim, M. li, ISits, Tiif. xvii, Fin. 3.) Ilhif priinilivi' fitirils coiiiiiiK fmiii the "' icccplioii iuiir.s" on llic siiiliuc of tlic Ixidy 111 Ilif cintriil oi'naii. Hiil llic |iriiiiitivc lilirils };oiiiK to the iiiiflcus. Uliiih- oilier liliiils. A'. '(. p.. iiciiropiliiin aiiliiiiiaiii posttiiiis ; .V. I., iicmiipiluiii tcKuniriiliirii ; .V. 11. I., ni'iiropiliiin aiitciinarii latcrali' ; .V. n. m.. iii'iiidpiliiiii aiili'i iiarii iiii'dialc; /(. motor priiiiitivi' tilirils to (Icnov iinisclcs from A', n. p. ; l>. Motor tiliriis from .V. ii. I. to ticxor.-i ; //. molor tiliril.s from A', it. in. to f.xtcnsor.i ; c, motor liliril from .V. n. m. to llcxois; c . motor liliril from V. (/. /. tocxttii sors: it '111(1 ('i, tilirils throwing aiitciiiia muscles mider iiuliieiiee ol' A'. ^; i\ liliril eoiiiierliiiK A'. ((. /. with .V. n. p. ; /. tihril throwing <'cll hody under ililluelice of neuropil ; ;;, motor tilirils extending from eell hody to muscles. removes all the t^'antjlion cells from the neuro))ils of the second antenna of Careinus and separates them from the whole of the rest of the nervons system by a circular cut and section of the * Bcthe, A. Das (Tentrainervpiisystciii von Careinus Maeiias. Ein anato- inisch-physiologischer \'ersiio)i. II. Tiieil (3. Mitthcilung). Aroh. 1'. iiiikr. Anat., Bonn, Hd. li. S. :583-453, i\:7 TIIK XKI'HONK AS TIIK I'MT. 27:^ O'snplia^^cul rniiimissiirc, so tlmttln' iicrvc of the second iilltciiMU is coiiiu'ctcH with ciul stalioiis (n(>uro)iiluni iiiitiMititii'ii II incdi- uli', latiTiilc ct postcriiis) ciitirt'ly ili'privi'd of duriiiji life is com- plete cessation of activity ])ossible. Repose iiiul activity are here, therefore, merely relative terms, tind are used tbroufjfbout in tbis restricted sense. Tbe pioneer in tbe investigation of tbe bistolojjfy of fatigue is undoubtedly tbe American investigator Ilodge.f * Op. nt., p. 2!);{. f Ilodge, ('. F. Some KfTccts of Stimulating (ianglion Cells. .\m. J. i'sychol.. Malt., vol. i (1887-88). pp. 470-480 ; Some KlTects of Klcctrically Stiuii.laling (ianglion Cells. Am. .1. I'sychol.. Halt., vol. ii (1888-'8i)), pp. !{7()-402; The Process of Keeovery from the Fatigue occasioned by the Hlee- trical Stimulation of Cells of the .Spinal (ianglia. Am. .1. Psychol., Worct^s- ter, vol, iii (18iK)), pp. ,')i}(t-r)4l5 ; A Microscopical Study of Changes due to Funitional Activity in Nerve Cells. .1. Morphol., Host., vol. vii (18!)3-'!);5), 275 r ni '■\n ^4 1 m I, -f ^m 270 TIIH NKIlVors SYSTKM. Ill a .series of l)rilliiint oxperiintiutiil rosoanihos ho has es- tal)lislie(l the oxistonco of definite! niorplioloj^icial alterations in the cell bodies of Tienroiies a<'('oin[)aiiyiii'.i, l(!4),and later he was ahle to demonstrate similar chan^'es in the nerve cells of animals after a lonj? day's exeniise (English sparrows, swallows, pigeons [Figs. 1(!5, I(»(5j, and honey-bees). On comparison of the non- 'Wm ^' ». -■■a' "^^K- w; . Tx. r: ■-■■ ■■■^ Vm. Ki;?. .Section tlirniiKli ^anKlion on doi'sjil root of lirst tlioriicif ncrvct of ait. Osniic at'id. lliistiniiilatt'd. i Al'trr llod};*'. i fatigued cells (in case of faradic stimulation, the cells of the spinal ganglia on the side not stimulated ; in the other in- stances, the cells of animals captured in the morning) with pp. !)5-168; Die Nervenzelle bei der (}cburt uiid bcim Todc an Altcr- scliwilche. .\ii)it. Anz...Tena, Bd. ix (1H!)4), S. 700-710; Chimp^s in ()anf,'Ii<)ii Cells from ISirtli to Scnilo Death; Observations on Man and Iloney-Mee. .1. riiysiol., ("ainbridf^e. vol. xvii (1K!)4), pp. 12!»-l;{4; A iMil ria that this is due to forma- tion of acid by the cell with consc(|uent slight solution and difl'usiou of the material which stains blue will, considering I 1 11*! #r 35fSVi?»^^™. f !> i!r i i : 2S0 TIIK NKK VOL'S SYSTEM. t;|j -Hi|l| what is now ktiowii of the N'issI bodies, (ioiibtloss niot't with opposition. Studies ol" tiie nervous system of liibeniiiting uniniuls have beei 'indortaken by Jacobsoiin.* He found, however, no dis- cer Iteration in the motor cells of the ventral horns. 'v- i mil Fid, UiH. — Two motor cells from luinlmr i('};ilimate and slaiiiecl in tiduidin blue. ), pp. 389-421. J Goldseheider, A., iind K. Platan. Norniale uiid pathologischc Ana- tomic der Nervcnzellen auf Gruud der nouoren Forschungen. Berlin (1898), S. 35. -. — ^^ w TIIK NKLUONK AS TllH UNIT. 2sl motor ri'ffion of the (UTchral cortex and tlicii cxaniim' the ci'll bodies of tlu^ (rorrcspondiiifj lower motor iieurom-s (ventral lioni cells). In the same way the lower motor neurones could he in- directly stimulated hy way of the peripheral sensory neurones (spinal ^an^dion colls, dorsal roots of spinal nerves), after which the morj)hol()^ical appearances of the ventral horn cells could be comparel' the li^froitl masscH imdcrf^'o this clmn^c, (ttliciv rt'niiiin iipiKirciitly entirely unalTected, (ir are at nutst lint sli^'litly altered. In prolonj^ed poisoning' tlie j,M'onnd siihslaiieo A, i*"^** '.^' '^^. A ■■mu (I If Fi(i. 170. — Thccd'cflsdl pliosplioriis poisoiiiiiK upon tlu- iifiirimt's. ( .Vftcr V. Nis.sl, AIIk. /Isclir. r. I'syi'liiiil.. etc., I5crl.. I?«l. iiv, lHi)7. i The icll in tlic upper ri^lil-liaiiil conu'r is nnniiiil ; mII tlic other cells sin iw the elleetsdl' phosphcirus poisiiniiiK. may lie involved, and the nuclons of the cell diminishes in size. Miiny of the cells ])re,'^cjit a ditfnse stiiininff, the limits of the NissI liodies heiiifj; hut very indistinctly visihle (Fijf. ITl). For Nissl's tindinn of the cell (Kij;. IT".') is the tirst to he alTeeted hy poisons, and that the alterations of the aehroniatie sui)slanee follow with a rapidity which depends upon the kind of poison and the ty]»e of (!ell coneerned. Alterations (»f the (diroinatic; part are reparahle, hut he doubts if this ht; true foi' the adiro- nuitic i)ortion. The alterations in the |)i'riphery of the cell come on earliest ; ehanj^es in the nucleus occur last, when the resistance of the cell has been exhausteil. ("hanr the ulkiih>i(l, even as early as three iiiiiintes after suheiitaiieoiis injection. Alterations in the nucle(»li precede tiiose in iiio tigroid nuisses, uceording to (loldscheider and g^pS" pfeii V ^ ^'^Hljb^ ■v^r'^;^ |;^^,i A^r ,v: ^^A,^ ■^^khy^l^' ..>»■' Fid. 172. -Two s|(iiiiil Kii'ifjliiiii cells sliowing poriplicnil fliroiiiiitolysis in arscn- iciil poisdiiiii},'. (.\t'l<'r K. LiiKuro, Kiv. ili piitol. lurv., Fiicii/.i'. vol. ii, lsit7, >'. r>:< KiKs. ~ and :{. I Siihliniatc fi.xation ; hii-iimto.xylin .staining. Flatau. No distinct proportion conld be established between the morphological alteration and the amount of functional dis- turbance. Functional disturbances were recovered from some time before the iiistological a])peiirances hud again become normal. This absence of any strict proportionality between the vis- ible morphological changes and the degree of functional dis- turbance is of the highest importaiu'e, and such incongruity should hold in check those zealous investigators who, without adequate data, are ready to inter])ret every histological finding in terms of the clinical symptomatology. As a matter of fact, m uU, TIIK NKUUONK AS TIIK IN IT. 287 the altcnitioiiH in llic tcIIh in iiciitc iiiid clironic poiHonin^', so fur iiH tlicy have hi'cjj Htudicd up to the prcHctit tijnc, can Hcar;'('ly l>t' l>roiif,'lit into relation willi the dinw-al syrnptonirt. The occiirrcnct' of Nissl's "acute cell disease " (c/V/f ////'/v^) in a whoh' series of entirely difTereut disease-jjictures is further evidence of our lack of infornuition with re^'ard to the corre- spondence of the th'tnoiistralih' histolo^'ical alterations in the neurones and the sytnptctnis met with during' life. That the histological alterations have functional e(|uivalents, however, no one eun douht, and other investigators have gone too far in dcnyinj^ the e.xistence of any relation hetween the tu-rve-t'ell chanties demonstrahle in poisoninj,' and the nervous disturh- ances met with durinj,' life. .Ml that we can say at jiresent is that the appearance and disappearance of the nuijority of the clinical symptoms are independent of the relatively gross intra- neuromil struct ural alterations thus far descrihed. Tlu' corre- spondence in all prohahility lies in the liner structural altera- tions indiscoverahle hy our present methods (»f examination, and will first be ascertainahle when advances in technique per- mit of the application of procedures which reveal such finer changes. Very important from a therapeutic standpoint are the in- vestigations of Hrauer.* Thi,>-' investigator studied the cell bodies of the 'Huronos in the central nervous system of some twenty-three rabbits poisoned by mei'oury. Some of the animals wer(^ subjected to acuci', others to subacute, still others to chronic poisoning with this metal. The poison was given by the mouth, subcutaneously and intravenously. In addition to the marked altenitions in the kidiu'ys aiul intestines distinct paralytic phenomena on the part of the nervous system soon became manifest. The paralysis gradually increased as the poisoning continued, the relle.xes were exaggerated, aiul the aninuds exhibited an outspoken ataxia. Sec^tions of the nerv- ous system studied with Xissl's method showed large numbers of altered cells in the ventral horns. Among the altered cells there remained a considerable number which did not appear to be affected, although tlie relative proportions varied much in different aninuils. Very frecjuently Hrauer met with localized * Hrauer, L. I>er Einfliiss dcs Qucoksilhors auf das Nervensystoin des Kaninchons. Deutsche Ztschr. f. Nervenli., Lcipz., Bd. xii (1H97), S. 1-67. ;ii It /I II 1. ■ Ij ll|.'L m iiiiiij 288 TllK NKHVOUS SVSTKM. li ;• m aroas in individual colls in wliicli tif^roid bodies wcro boj^inning to break up. TIk! line particles l)ecaine scattered through the {fround substances, and the cell contents often presented a dust- like appearance. The bearinj^ of suidi observations ujjon the treatment of syphilis is obvious. It would take too Ion*:; to consider all the reports of stud- ies of into.vication even if only those made recently were referred to. Anionjif the recent researches, those of Sarbo * on ana>mi(; alterations, Vas on nicotine poisoning, Dehio on strychnine poisoning, Manersi on strychnine and chloroform poisoning, Berkley on alcoholic and ricin intoxications, Masettif Fi.!. i7:i.-.\n..iv.M-..|iinm>a imrt.f *>" autipyriue intoxication, of tJK' spinal .Old . I. •priv.di.ii.luo.i lor I>andi t Oil bromine, (M)caine, six hours tliriilluli liKiitlirc of the ill)- . . . . . (loiiiiiial aorta. ( AitiT (1. Marines- meotiiic, and antipyriiie poison- co, l,a I'lfssf iiit'dicalf, I'ar., 1S!)7, p. •,,, i...,i,u(^ .,.,,1 VX'., ....:..,,*,,.. t» 45, n. V.) Tlu' p.iipii..ial poiii.Iii '"K. l^iislett and Warrington •» oftlifcytopiasiiKoutaiiisoiiiya iVw oil lead poisoiiiiig, Wright 11 on tigroid masses, altlioiif;li the latter . , ' . • ,, , are still iimiu'ioiis near tlie mieleiis. broilU tO poiSOlllllg, Moiirck and * Sarlio. A. I'cber die KiiekciiniarksveriliKU'riiiij^oii iiach zoitweilif^er Verschliessmif^dcr liiiiicliuorta ; eiii Meitraj; /iir Piitlioiofjifiles (luiif^lioiizell- kerne. Neurol, ('i'iitfall)l.. Leip/.. 15.1. xix (iHi»4). S. (iB4-d.. Wiesb,. Mil. ii (1H!);{-'!M). S. 2r)7-'JH4, * Ija.dett, K. K., and W. W. Warrington. 'I'lie Jlorbid Anatomy of a Case of I.o-.i I'aralysis, Condition of the Nerves. Mnscdes. Muscle Spindle.s, and Spinal Cord. i?rain. Lond., vol. xxi (IHDM), pp, 234-2:51, II Wright, It. K. The (."erebral Cortical Cell under the Influence of l*()isonoiis Doses of I'olassii Bromiduin. Brain. Lond., vol, xxi (1898), p[i. 18G-2a3. TlIK NKTUONK AS TIIK INI'I'. 2S<> Mess* on llic cITtn'ts of vjirious poisons, should he iiiciitioiKMl. Till' t'tl'i'ft of (MittiMt P. Ui'ss. I,('siolis lines dcs (•('Hull's liiol rices (le Im iiKieiie (■'|iiiii("'ri' duns les divers ('■litis d eiiiiKiisoinieiiu'iil. Uev. iieiii'ol., I'lir., I. \. (l.sitT). N(i. ',»:{. + liiilu's, \'. I'elier den ImiiIIuss der verseliiedeiien inrecl ionen .■mf di(^ Nerveiizellcn des Kiiclvcinnarks. iJeri. kiiii. Wclinselir., 15(1. ww (IS'.IS), S. C ; ;i() : oil. \ Heck. .\. i>ie N'eriinderuntceii der Nerveiizellcn lieini ex|ieriinentellen Tetanus, drvosl iielil.. IJiidiiiiesI, vol. xxxvii (1K!);>), No. '.V2. iiel'. ini .Neurol. (Vntrallil., \a'\\,/... ISd. xiii (IS',14). No. ^M. * Dejerine, .1. Sur la eln'oiualoiyse de la ecllule nel'veuse au eoiirs des iiifeclious avec liyiierllieruiic. ('oni|it. rend. Soc. dc liiol., I'ar., 10. s., I. iv (18!)7). p. 12H. II Kwinj;. .1. Studies on (iiiiifjlion Cells; a I'reliniinury Comnnniieaiion. Med. ifee.. N. Y., vol. liii (ISitS). pp. rtV\ ,->!7. '■' Cidldselifiiler, A., und I'". Mruscli. I'elier die N'eriinderunp; inenseliliclier Nerven/.ellen boini Kiober. Fortselir. d. Med.. Herl.. Md. xvi (1H!»H). S. 12(M'.>S. {) (ioldselieider, .\., and I'l. I'Malau. Norniale und pulliolo;;isclie Aiuiloniie der Nerveuzellen auf (irund der neueren l''or.sfhiuit;i'ii. 15(M'lin (18!W). J liUpiro, I'l. .Mti'mzioiii dellc cellule iutvosr iiella peste bubbonica sperinientale. Uiv. di patol. nerv., I''irenze, vol. ii (1H!(T), pp. '.'11-'.] M. JNielioll.s,,!. Sludiesol'Tyithoid Kever. .1. Mxper. .Med., N.Y., vol. iv (IH!)!)). { Sabrazes, .1.. el ('. ('abuinios. Noti> sur los lesions dos lu'llules iiervoiise.s de la inoelle dans la I'aj^e Innnaint'. N. ieono;,^ de la Salp(*tri("'i'e. Par.. I. x (1S',»7), pp. l."i.">-t(M. *♦ Marinesi'o, (i. Sur les l(''si()ns dii svsleme nerveux central an eours des maladies inl'ectieuses. Coniiit. rend. Soc. de biol.. I'ar., 10. s.. I. iv (18!>7), pp. 7!»r)-7'J8. ff Ai'ijutsto. \'., ed. I'l. Pusateri. SuH' aiuitoiiiiii |>iitol()}j;iii dejili eleiiuMiti nervosi lu'ir uremia aeiila speriincntiile. Hiv. di jmtol. nerv.. I''irenze, vol. i (iMSHi), pp. ;{77-;!.sr). XX Hallet, (i. I,es l(''sions e(''r(''brales de la piiralysio jjein'Tiilo etutliees juir la metliode di- Nissl. Ami. nied.-psvcliol.. Par., H. .s., t. vii (IH'JS), pp. 44H-4.'jO. 30 I. I ■|..S? m m I 1 '. \ h V mm lm[iiP 290 THE NERVOUS SYSTEM. Dutil,* Boedoker and Juliusbnrger,t Cramer,J Dojerine and Thomas,* Frie(lmann,|| Alarinesco,^ Monti,^ I'opolf,! II<)(!li4 Qaervain,J Sacerdotti and Ottolonglii,** Schatt'er,f f Lugaro and Cliiuzzi,JJ Soukhanofl,*** and 8troobe.|||| * Udllet et Dutil. Sur quelqucs lesions <^xpi'riinentalcs do la cellule norveuse. Xllth Internat. nicdic. ("ongr. zu Jloskau, Neurolog. Centralbl., Lcipz.. Bd. xvi (1897). S. 015-91(5. f Boedekor and Juliusbuiger. Auatomischc Bofunde bei Dementia para- lytica. Neurol. Centralbl., Leipz., Bd. xvi (1897), S. 774-779. X ( 'ranier. A. Pat iiologisch-anatoniischer Befund in einom acutcn Fallc dor Paranoiagruppo. Aroli. f. Psyeliiat. u. Xorvenkr., Berl., Bd. xxix (1896), S. 1-24. * Dojerine et Thoma.s. Sur I'absence d'alterations des cellules ner- veuses do la moelle ('j)iniore dans un cas do paralysie alcoolique. Conipt. roiid. Soc. de biol., Par., 10 s. (1897). II Fricdmann, M. Uober progressive Vertinderungcn der Ganglienzcllon boi Hntziindungen, nobst eincin Anliang iiber active Verilndorungen dor Axoncylinder. Arch. f. Psychiat., etc.. Berl., Bd. xix (1887), S. 344-268. ^ Marinosco, Pathologio de la cellule nerveuse. Rapport presento au Cdiigros international de medocine a Moscou. Paris (1897). ^ ;Mouti, A. Sur I'anatoinie patliologique des olonients nervoux dans les processus provenant d'emboli, me cerebral ; considerations sur la significa- tion pliysiologique des prolongemonts protoplasmatiquos des cellules nor- veusos. Arcli. ital. de biol., Turin, t. xxiv (1895-"96), pp. 20-;5;3. I Popow, X. Arch. f. path. Anat., etc., Berl., Bd. xciii (1883), S. 351-3C6. I Ilooh, A. On Changes in the Xorve Colls of the Cortex in a Case »( Acute Delirium and a Case of Dolirum Tremens. Am. J. Insan., Bait., vol. 11 V (1S97), pp. 589-606. I do (^uorvain. P. Uebcr die Voriindorungon des Centralnorvoiisystoms bei oxperimenteller Kacliexia tliyroopriva dor Thiere. Arch. f. path. Anat., etc., Berl., Bd. cxxxiii (1893), S. 481-550. ** Sacerdotti, C., e D. Ottolonglii. Sullo altorazioni dogli olomonti nervosi nolla (liserasia uremica sporiiuontale. Riv. di patol. nerv., Firenze, vol. ii (1897), S. 1-8. ff SchalTor, K. Ueber Nervcnzollveriinderungen wiihrond der Inanition. Xeurol. Conlralbl., Leipz., Bd. xvi (1897). S. 832-8:57 : also Das Verhalton der Spinalganglionzollcn bei Tabes auf Grund Nissl's Fiirbung. Xeurol. Centralbl., Leipz., Bd. xvii (1898). S. 2-7: also Uobor X'ervonzollonvoriindor- uiigen dos Vordorhorns boi Tai)es. Ein Boitrag zur Pathogenose der tro- phischon Storungon der Tabes. Monatschr. f. Psyeliiat. u. X^eurol.. Berl., Bd. iii (1898). S. 64-98. 11;. Lugaro, E., e L. Chiozzi. Sullo alterazioni dogli olomonti norvosi noU" inaniziono. Riv. di patol. nerv., Fironzo, vol. ii (1897), pp. 394-400. ** SoukhanolT, S. Sur I'histologio [tathologique do la polyin'vrite dans SOS rapports avoc los lesions de la cellule nerveuse. N, iconog. do la Salpe- tricre. Par., t. x (1897), pp. 347-354. III Stroobc. II. l'(^l)or Voriindorungon dor Spinalganglion bei Tabes dor- salis. Centralbl. f. allg. I'ath. und path. Amit., Jena, Bd. v (1894), S. 853-855. THE NEURONE AS THE UNIT. 291 In the investigiition into the changes in the luiman cerebral cortex no one has thus far had so mucli experience as Franz Nissl. In a recent paper * he distinguishes seven forms of alterations in the cells of the human cortex: (1) Acute cell disease; (:*) chronic cell disease ; (:{) severe cell disease ; (4) combined disease forms; (o) vanishing of cell; (G) simple rarefaction; (7) granular breaking up of the cell.f Xissl lays much emphasis upon the first of these forms, the rio-called acute cell disease. According to him it runs the same course in every instance, hav'ng always the same termination, and when it has once appeared it involves all tlie cells of the cortex without exception. The changes are so characteristic that, after once • jing them, one can make a positive diagnosis without difficulty. The disease does not aifect a part of the cell only but involves the whole neurone, the staiiud)le as well as the unstainable substance, the nucleus as well as the cell body, the axone as well as the dendrites, all parts being involved apparently in the same degree. In this form of neurone change the unstainable substances are so altered that they become stainable, a fact which makes Nissl think that liis " unstain- able substance " consists not only of a fibrillary constituent, but, in addition, of one or several other substances. Xissl finds this acute cell disease not only in acute paralyses hut in a great variety of psychoses, and also in patients who have not been the subjects of mental disease in the ordinary sense, but who, succumbing to various disorders, have before death been partly delirious, partly somnolent. The involve- ment of all the cells in the cortex is an exceedingly interesting feature, and one met with rarely in any other form of disease. An instructive paper dealing with the alterations discover- able by Nissl's method in the human cortex is that of August lIoch,J of the McLean Hospital, Waverly, Mass. Working in * Xissl. F, Norvcnzt'lli'ii mid jj;riiue Subslanz. Miiiich. iiu'd. Wehnschr., l?il. xlv (1H!»8), S. 988; 10:>3: lOGO. t In this country Iloch (Ilocli. A. On t'hangos in the Nerve fells of the Corlox in a Casp of Acute Delirium and a Case of ni'liriuni Tremens. Am. .1. lusan., Halt., vol. liv (181)7), pji. r)8!»-G()G) has described one ease in wliieh the "acute cell disease" (acute Verdndenmg) and another in which the "severe cell disease" (nrhwere IV/7'//)(/c/'«;ir/) of Nissl existed. His descrip- tions of the changes are the fullest and most accurate hi the English language. \ Uoch. A. Nerve-Cell Changes in Somatic Diseases. A Preliminary Communication. Am. J. Insaii., Bait., vol. Iv (1898), pp. 2:11-240. t- ,5' (i- ■ 7 , ■ ■! ! ' itit I ll' 2[)-2 TIIK NHR VOL'S SYSTHM, . if! I mm III i Nissl's liibonitory at llt'idellH'i'^, Iloch liud l)eou iin])res.so(l witli tho fiT(|iu'iicv with wliicli cliaiif^U's wciT t'ouiMl in the cortical nerve cells in individuals dead of diseases of ditt'erent kinds. Kecogniziuf^ the iin])ortanee of a tlioroiif:;!] knowledge of the possible ehanjjes in the eells in somatic disease I'or the inter- pretation of the patholover shows a purplish hue. Instead of the honeycomb appearance, the pro- toplasm may be " crumbly-looking." While these changes occur in the smaller pyramids and the cells in the fifth layer and in a few of the larger pyramids, Iloch finds a very different a})pearance in most of the larger pyramidal cells and especially in the largest pyramids (not the motor or Betz cells). There may be but little alteration in the extermd form of the cell body, but there is nuirked (duinge in the distri- bution of the stainable substance throughout the cell. The stainable substance is seen at the base and at the sides of the pyramid, sometimes forming a rim around the periphery of the cell ; often this rim is not continuous but consists of a number of separate " crumbly " portions. The basal processes are much more altered than tlie large apical dendrite, especially in the larger cells. The alterations in the nucleus are very character- istic. No nuclear mend)rane can be demonstrated, and the in- terior of the nucleus shows no trace of a shar]) design, in Nissl preparations frequently looking entirely homogeneous. The nucleolus is, however, unaltered. The change just described I i TIIK NELKON'K AS TIIM I'MT. 293 H(»cli (Icsignatcs " altcnitioii with rarefaction around the nu- cU-iis." As a rule the larj^o motor cells look entirely normal. In two of iiis cases Hoch met with an alteration in which the cells may he compared to vesicles. Around the nucleus he found a narrow rim of "crumhly-lookiiif,'" substance, then a clear area, and at the periijhery of the cell body another ac(!umulation of " cruml)ly-lo()kin '■ ' ^1 » - ■ 1 1 ! . If" ' 11'" " 'i' ) V \ " 1 1 > U - 1 • 1 ;;» m I'.- 1 I I i I f! li *' i||[ ?r I' 'k. PlW: 294 TIIK NKIJVOUS SYSTKM. siiKM' in liis proctMlnrc, its in that of Hcviin liCwis, fi'()?;t'ii sections iin> (>in]ilovi'om'ern(>d ai)pear somewhat swollen and there are marked chancres in the a))pear- auce of the protoplasm, most advanced itear the axone hillock. These chaufjes consist, as has already heeu stated, in a hreakintr up into tine granules of the tijrroid masses with diffuse stain- ing of the achromatic suhstatice of the coll. If the changes ho very marked, as is often the case in young animals, the ti- groid massi's may disajipear from a large portion of the cell hody and the nucleus may ho displaced to the side of the coll. As a * Mnriiie; ■foiKJaire.s el TIIK NliriJONK AS 'IIIK IM'r, ynn result, the typical Hticlioclironic iirnuiffciiiciit of tlic li^nnd a^- ^Tcpilioiis inside I lie liody u\' tlie c^ell is eidirely lost, in latis st;i|jes in the dendrites also, iind what staiiiahle suhstanee is left a|t|tears in the I'ortn oi' line diistlike particles or as a dilTuse hlne stain (i"'i;f. 174). These secondary tdian^'es in the cell liodies of neurones, the evidence ol" " reaction at a distance," may lead !<» the death of the cell in case the peripheral connec- tion can not h(( aj^ain made, although more often after a certain lenj^th of time tluuv is u {i;radiud restitution of the nor- mal appearances, due, Nissl thinks, to the forinati(»n of new connections. Accordiuf^ to Marinesco, ther(M)ccurs durin^^ the process of repair proj^ressive hypertrophy of the tu-rve cell up to a })eriod as late as ninety days after the operation, lie he- VwwH that this increase in size of the nerve* cell is for the pur- j)ose of assistinfX in the re|»air of the lesions in the divided nerve, and thatconiplete return cd' function occurs only after the anati>niical continuity of the [teripheral nerve has hoen re- established. 'The chauffes in the cell hodies fcdlowing the dirtn^t action of toxic suhstances upon theni dilter, as a ruhf, markedly from those just deserihed. Without j,Miin. 41-47. m U 'i^ :ni !■ ■ 1 , 1 i // I 'I ' . t- - - -* f -V ' 1 M ti i V V !■ f I '^W UU I iiit 296 THK NKKVOUS SYSTKM. altlioiifrli witli ciTtiiiii iiioditlciitions iiiul rcsorviitioiis. The iiiiiiii t'lnpliasis in the " secoiuhiry " lesion is to be laid upon the fact that the process begins near the axone hillock. Less impor- tance is to be attributed to the peripheral chronnitolysis in the Fl(i. 17.').— Cells from tlic huiiiiin s|)iiml cord in tiiiilciiiic (■crchro-sitiiiiil iiiciiiuKitis. ,1. two cells In ilie ventnil horn. The imcleiis of one of IlieiTi is not visihle : thiit of the olh is (lisphiced to the tide of the cell. Marked disorfriinization of the stainnhle siihstance of Nis.sl. the secondary result of the involvement of the ventral roots hy the meningeal inllammation. /(.cell from the nucleus dorsalis showing' alterations which result from a lesion of the a.xone of the cell. ! 'S TIIK NKIUON'K AS TliH TNIT. 2J>; " primary " lesion, since in ricin pois(tning,* for example, elmnjres may have occurred in tlie N'issl bodies tliron<,diout the cell l)ody at a very early period, even het'ore there is actual chromatolysis. In the study of the ])athological anatomy of human cases the ^■,_../:^;-';>.V: Kui. 171). — Kdiir nerve ccHs rrom the nucleus iiervi faciiilis of a rabbit fifteen days after section of the nerve root. Drawiuf; inach' from oni' of ,1. Krlaiifrer's prepaKitioiis. results of such investigations should at all events be borne care- fully in mind, and it will be the duty of the pathologist to en- deavor to distinguish in the various forms of nerve lesion the alterations which depend upon " reaction at a distance " from f\ * Stucliod in tissues of exporitnentnl uiiinials kindly supplied by my col- league, Dr. S. Flexner. 2J»H TIIK NKUVOl'S .SY.STKM. Fio. 177. — Siniil.'irity (>r<'linnf;t's iivihIiu'imI in cell liodics dI" lnwcr iiuitor nciironrs (11 l>.v iiiltiiif; tile Mxoiii' :nnl i~Mtiy cutliiifj tlic (•(ivrcspniiiliii); ilmsiil rimts. (ACtcr \V. H. \V;iiiiiigtoii, .1. I'liy'siul., Ciiiulir., vul. xxiii, IS'.ls, pi. i, l"i«.s. 1. and ;<. .\. li nuniial n )!' tlif vi'iitr.il lioi'ii : |{, vciitial Inuii cell t'limti't'ii (lays after scctinti of iiiii(".i)(iinliiif; vcnlnil rimt ; ( ', <'cll (Vinii (liirsn- lalonil unuii) of xcntral .sil roots of the cauiia t'H'iina. Iwcnty-tliri'i' day.saftor section of sovoral (Ui TIIK NlirWONK AH TIIK INIT. 20U tlioHf wliicli lire iIm' itsiiII i>\' iIm' ilii'i'ii iirlioii iiT iitivsi' in hmIii- tioii ill till' 1)1 1 iiikI lynipli ii|ioii llir irll liiiilit'M hihI di'tiilrilcH ul'llii' iicui'niH'H. Ill I'i'i'ttiiii |iiil IidIo^mciiI I'liiiililioiiH till' inii- iniif iiiiiv (IdiilillcHH lit' iilTcflt'd in ImiIIi wiiys Hiiiiiilliiiii'oiisiy. I liiiv*' riMinil tliiM to 1)1' triK' ill <'|iiil<'iiii(; iM'i'('lini-s|iiiiiil iiiiiiiii- gitiH. 'Till' li'HiniiH in tliiM ilisniHi^ in the nAln (if the vcnlnil linrtiH iin> in |itirt tlniHc of rcurtioii at. u ilistiini'i', in |iiirl lliosr of pri- niinv inliixii'iiiinn nl' tlii> nri'vc ct'll. I iiin ol' llii> ti|iinioii tliiit. I lit' Iniincr si'i (if li'sidiis wliii'li liy the wiiy iin- liy t'lir I lie nmif |in»iioinnTil iirc I lie rcmilt of injury to the tiiolor iimiIk liy IIh' ini'iiingi'iil intliiniiiiiil idii, t III' lattrr tu llii' ^'I'licnil to\ir I'lTi'i't of till' |M)iHonH |ii'(hIu('i'(I liy llir liucloi'iii wliicli ciiiiki' tliii (lisi'llHO. Ili^dily iiilt'rc'Hting in this luinncction iiro the rcHiiltH nl)- tiiincil by Wiirrinj^toii,* nl' iiivcriMMil. Hit liuHiMit. the dorso- latcral f^roii|i of cells in I host' si'ifincnts. In the inonkcy a ^M'cat many tells are found ultcreil on tlitMipiMiMilc siile. 'I'lie alterations, iis will lie seen in \'"\}f. 177, are similar to the t'liaii;^i's wliieli result when the axolies of these ttells are eiit.. \\arrin;:lon alt rilnites the chaiij^'e to the withdrawal of the alTereiil impnlsi^H which normally impin^^rt* on the eornnal cells, anti compares his resnlls with those olitained from the well- known t'X|ierimeiits of Molt, and Sherrin^fttni,! hy which it. was shown that section of iJie dorsal roots leatls to pronoiiiici^d loss of inuscniar tone, ataxia, and marked im|iairmeiit of voluntary movement. TheHe Htudics of Warrington, tak(!n with those of Marinesco and van (Iehn(diten,J should make lis keep in view the possibility that the lesion hitherto supposed to be typical of * W'lirriiiKtnii, VV, 15. (in llic SlriHtliini! AlltTHlioiis obHtTvet! in Nerve Cells. .1. I'liysiol., ('iini.ridp', vol. xxiii (iNilH), pp. 11!> 12!». f ISidtt, I'. W., Hint ('. S. Slicrriiif^liiii. i'lxpi'i'iiiiciils iipnn Ihc [nflurncc of StMisory Nerves upon Moveimiit ami Nutrition of I lie Liiiilw. i'roc. Hoy. Sof. liond., vol. Ivii (IHliri). pp. :iiri-lHl. I \'nii Oi'lmclilcn, A. l/iiiiiitninif fine dc In ('ciliilc iiiTvciisc. XIIlli Coii^ivH iiiteriiiitioniil tie iiK^di'ciiie Ti iMoscoii tH07, liefer, iiii Neurol. Ccii- tiullil., I.eip/,., Hit. xvi (1K(»7). No. li>. 'ii!i *to;.|! i ! 'ji« II ;ti)o tllK NKUVors HVMTKM. w vt>ii(iii»n Hi n iliMim^ro ihic toliwion of tin imuit' nni\ ili'iiowl u|>i>n im iniivi'lv ilitTi'H't\l ciniso iiiitnclv, llu- iciiHnnl id iilVn cnt mipulm'H fioiii ihr dcmlriti'H iiiui i-t'll IukIji'm nl' the itrnriincH roniTinnl \t\ mli'Vi>sl>!il>l\ iiliciiilv mifmcMfnl ilHi'll' titlhr iniitiliol' uinnv- H" solnMc \o\w 'j\ilist:)nc("( im<> i'!ip;»l>li> of piodni'in^: w il li \\\ )i lonipsn-.M nt'l\ 's<>"iiS witli nmliDViiilvil. i Artvv ,\. U nf iVliiii' S, •■/ m A l| ^l--./- t. V I'm Kii i;il'fi t'lol ■■iilllli l;il Iiiiii'ihi'mI lic.cly (i iii|iiriiliiii I Mill \ U.ilil^i hii'lii II I; riiliiii, Nniiiiiilr iiml lull IkiImi'Ii III \iiiiliiiiiii' i|i r Nii vi ii/.i Hi ii. ili . III! I , I'^IIM. I'll I \\ , I' ii! '.' \ VI iiliiil Ikii II 1 1 II >•!' Ilii' lull' I II I i!iiiii|i is mIhiwii HINill Mini ('llMlltl'lllI'M'JI' t ll|Mi|l ll'tlllllM Idxillf II III I II II t i I O X I llC, iiinl ol' KiMiipiirr iiinl ruliiirk | mi Iml iilisiiiiH |iiiiM(Miiii^r ll in ♦ (idliNi'lii'iiliT. /\. mill V, I'llllllll. Ki'iiiiliiKM iliT Sliiifliir ilir (liiiiL'liifi- /I'lli'ii (\ iii'lriiK vim (liililsclii'iili'i), \'i'ii'iii I'l'ii Imiii'Ii- Mi'iIitIii. IIitI Ivi'|ii|i|ii'iMi'iil ilii Ii'Ihimi'< rl riiiiiniiniti'- imli t(''liiiiii|ii(' I Alwlr.|. Hull, il iih'Iii. Snr. mi'il, il. Iic'p|i, ilr fur., '.\. s., t. xv nMllHi. pp. !lll KM. t Kt'inpiirr, W. iinil ll. I'lillnik. I>ii' Wiiliiiin,' i|cs Untiili-imiHloxIns (l''l('isi'lii;ifli'H) nml -ii'liiiw •^pi'cill'^cliin ;\iililipxiiis imf i|ji> Ni'rvi'ii/i'll<'n. DiMilsilic iiiimI. Wiliii-^ilii.. I.i'ip/. II. UimI., IIiI. xxiii (|M));>, S. 505 .-i07. ! 302 TUE NERVOUS SYSTEM. known that if niiilon-nitril bo injected into a rabbit, liydro- cytinio poisoning quickly results, leading to the death of the animal, after from twenty to thirty minutes, with paralytic and dyspnu'ic phenomena. If, however, the aninuil has been in- jected a few minutes before with a solution of hyposulphite of soda it quickly stirs about and recovers. It is supposed that the sodic salt acts as an antidote by giving off sulphur which unites with the cyanogen radicle. In animals killed with malon-nitril distinct alterations in the Xissl bodies can be made out (Fig. 178). In animals treated with the two substances and killed after nineteen hours certain alterations in structure are still apparent, though after seventy-one hours the cells are again normal, f Vlscheider and Flatau have compared the findings in such instances with those resulting from the artificial heat- ing of animals in the thermostat up to 42" or 44°. If the aninud be taken out before death it is flaccid and incapable of moving. The ventral horn cells of the cord examined at this period are seen to have lost their normal structure ; the tigroid bodies are replaced by light-brown opaque masses and by single granules, the whole cell being enlarged and the dendrites swollen (Fig. 17!i). If the overheated animals be removed from the thermostat and kept alive, gradual restitution of the normal structure can be made out afte several hours (Fig. 180), though the repair in the cells is not so rapid as the reappearance of function would lead one to believe. While the animals appear to recover very quickly from the symptoms, the regeneration of the cells after the nutritive disturbance requires for completion at least several days. It is evident, therefore, that changes in the chromatic sub- stance alone, as many have long suspected, do not suffice to ac- count for the clinical phenomena associated with them. All the evidence goes to prove that the f unctioii of the cell, as has already been pointed out in Section III, must be intimately associated with the integrity of what we call the achromatic substance. Marinesco and Chantemesse have studied guinea-pigs injected with tetanus toxine with the object of investigating the relation of immunity to histological alterations in the cells. After in- jection of the toxine alone they found typical alterations in the cells of the ventral horns, quite like those which have been de- scribed by Xissl, (ioldscheider and Flatau, and others (PMgs. 181, iS'-i). After injectiim of tetanus toxine and antitoxine they could find no alterations in the cells after three days, but if the anti- i 1 THE NEURONE AS THE UNIT. 3u;i toxic serum were not injected until twenty-four hours after the injection of toxine, (listliict alterations in the cell bodies of the neurones could still he made out, although it is stated that these were less marked than when the toxine alone had been injected. The various changes in the nucleus aiul nucleoli, to which considerable attention has been already directed by a number of investigators, afford, to a certain extent, valuable informa- tion concerning the state of nutrition of the cell, but they must here be passed over without further comment. f ^^. W V\i\. ISO. — Ri'covfry <(1" ventral liorii cell from cliiinjrcs imiduci'd l).v iirtiticiul iii- crcasi' of Imdy t»'in])<'niturt'. ( After (iohlscliciilcr and Flalan. Norniali iind liatln)lof;is(li(' Anatomic der Nerven/ellen. etc.. lierl., ISiKS, Taf. v. I'My. 'J.) Tile lifinrc sliow.s a ventral horn cell of the lateral Knuii) after eiglit lioiirs and a lialf of restitution. A warning concerning the necessity for obtaining very fresh material when Xissl's method is to be employed for studying pathological alterations may iu)t be superrtiu)us. Kot only nniy lesions in nerve cells change in appearance in pathological cases a short time after death (Marinesco), but normal cells may by post-mortem tdtenitions come to resemble those altered as the result of disease. We have to thank Meppi,* of Tram- * Ncppi, A. Sul • nlternzioni ciulaveriche delle cellule nervose rilevabili col metodo di Nissl. Kiv. di patol. nerv.. Fireiize, vol. ii (181)7), pp. 152-155. El'. ••a; WM i! ?f mm 'ipM!^i iiO-t \. ,^ TlIK NKUVDl'S SVSI'KM. •'^N *».♦ ♦r-^. /* tfi^i •'^i •A rl * ^ •'^ N« .1 /.is'<«7 /./tf^ B h^ I Vl<-, 1S1. KiVccts if ti'tanns tnxinc iijum (lie lowtM- nmdir lU'iivmics i At■|^'^ (I(>lc^sl liculcr Mtid FlMtMU. N'oniiuli- iiiui imtlioldirischc AiiMtuniic lioi- Ncni'ii /I'll.'ii. ifc,. l?.-rl.. 1S!)S. Tat', vi. FIl's. 1 miuI •,>.■> A. nnnniil motor vrnlnil luirn ('I'll lit' till' nititiit. sliowitm tyi iiu'lliod. li. vi'iitnil li< )U'iil stnictiirc a? lit'innnst rated liy Nissl' II two linui-s at'lcf intravciiDiis inicclinn of O.OJ (1 ci'iii., 4-t)i>r-i'<'nt siitiitiiiiO Iftamis toxinc, Tln" innli'dliis is swullcn ami iif a lighter I'ulur |)iaii Till' tiLTiiiil iiiassi's arc wliat pall'. llioiiLili tin- arr;iii!.'i'im'iil is well jin'scrvril. 11 ami TIIK NKllfONK AS Tlli; TNl'l' 1^1680 305 ■ tlHHk^ ■Hi '^^^IBi IHl'i '4'Pi^^B HBI/ ::i^^HH ■ ; 1 1 ! •'■1'! ■■,.'■» S-"\ / / tfsy n. fi /J»nr'/^ ^'z , I'll.. IS-.'. More iichiincrd st:ii;(s nf |iiiis(iiiim,' wil li lctiiiMi> lii\iiic'. .M'trr ( Icild- sc'liridiT ^iiiil I''Im(iii. NcirniMli' iiiiil |iMlli(ilip};isclir .\ii;ilcpiiii(' dcr Nirvcii/illcii, rlc. I?('fl., isiis, 'I'iif. vii, I'Mi-s. 1 Mini '.I.) II. iiiTvi rrll Croiri mi Miiiin.il (ivc cl;i.vs iil'd'r ;iii iiiji rlimi (iC (MHIKI ( I (■ciii.. soliil inn l:ti()0) IcImiiiis Idxinc. 'I'hi' ninlcdliw i'^ niiiikicllv >\v(illiii : I he li'jinid licidic'- iirc iilsci iniirli .swnllcn. mi id fire iiiiinircslly lircMkiiiL' up and iirr liccdiiiiiii,' iiilifiiiiimlrd. /). nrrvf ndl IViiiii Mil MiiiniMl I wcnly-iiiic liiiin'^ Mnd ;\ iinarli r mI'Ii r injiitiiiM id' O.ol M rem.. l-pcrMM'iit. siiliitiiiii t (cImiiiis loNiiii', 'I'lic niirlidliis is di riniiird. Tilt' tiKfiiid niMsscs slinw tlir lin(dv ki'miiiiImi' disiiilcmMtiiin. 21 I ►■ I I ■p V ■ 1; r J^S ' ' ■ ■: "I fill liJil :'^!^fi!l!H 3(»r> TIIK NKRVOUS SYSTEM. biisti'a laboratory, for a report on the changes, revealed by Ninsl's method, whieh take place post mortem in normal nerve cells. Since Meppi's arti(de another on the same subjecit has ap- peared by Harbacci and Campacci.* A. I loch states that the Hetz cells of the paracentral lobule are very resistant to post- mortem alteration. None of the methods at present at our disposal suffice, how- ever, for more than the discovery of what must be relatively extremely gross alterations in the structure of the nerve cells, and we can only hope that er(^ long advances in cytological technique will permit a deeper j)enetration into the mysteries of nerve-cell organization. These considerations bearing upon the physiology and pa- th(»logy of the neurone have led me further than I had inteiuled ; they must now be brought to a close. A series of phenomena have been touched upon, all too briefly, I fear, to do justice to them — Wallerian and Tiirck's degeneration, the changes in the nerve centres following amputations, the experiments of von CJudden, Bregman, Darkschewitsch, Nissl,and Flutau, the eifects of injury to the nerve centres through cuttij;g ofT of the blood supply, the effects of acute and chronic poisonings of the nen- roiu's, the phenomena of regeiieration, the incessant activity of the nervous structures, the absence of proof of any actual spon- taneity in the elements, the doctrine of tlie specific energies of nerves, the unity of nerve functions in the neurones, the direc- tion in which impulses are transmitted, and the iiitluence of activity, fatigue, repose, poisoning, etc., upon the structure of the nerve-cell protoplasm. This cursory glance, however, over nuiiiy phases of the metabolic and nervous activities of the neurones may have sufficed, I hope, to throw tlie essential ])()ints c(»n- cerning the nutrition of neurones into relief. The changes characteristic of tiie degenerations of Waller and of Tiirck prove to us that no matter how important the medullary sheatli may be in the integrity of the neurone for the nutrition of tlic axoiu^ inside it, it is certaiji that this Mitluence alone or to- gether with that of the nutrient supplies arriving through tiie nodes of Ranvicr caji not suffice for the maintenance of the ♦ Marlmcci. (\. c (i. ("ain[iii<'ci. Siillc losioiii CMdiivt'i-ichc dcllo ci'lliilc nervusi'. ]{iv. di pntol. iierv., Firenze, vol. ii (18!>7), pp. ;i;fT-;547. In k vsmm" TIIK NKUllONK AS TIIP] UNIT. 807 lu'iilth of the nerve fibre. There is not a little evidence, in- deed, favoring the view that the medullaiy sheath depends for its nourishment upon the axone, rather than that the axone is nourished from the medullary sheath. Some influence or influ- ences from the rest of the neurone, particularly from the cell body, are essential to the well-being of the nerve fibres. What is the nature of this influence or of these influences ? Does the axone actually receive all its nutrient material from the gan- glion cell, or does it depend, as would seem a priori much more likely, for the most part upon autochthonous metabolism, needing only the influence of the cell to which it is connected to govern the assimilation ? These are questions for which tlie data at command do not permit as full answers as we could wish. Every one must grant that the peripheral nerve fibre takes vd^e in large part of its own nutrition ; the presence of vasa ner- vorum affords sufficient warrant for this belief. Further, the evi- dence for its subordination to local processes of diffusion is to be found in the local injuries to peripheral nerves resulting from the circulation in the blood of soluble substances of a toxic nature — as, for example, in diphtheria. The key to the whole problem undoubtedly lies, as the neurone concept teaches, in the fact that the axone in all its parts, no matter how far re- moved from the cell body, is an integral part of a single (;cll. To explain the influence of the cell body upon the fibre, fiold- scheider has advanced a very ingenious hypothesis. Tie sug- gi'sts that it is most probable that there is an actual transport of a material, perhaps a fermentlike substance, from the cell along the whole course of the axone to its extremity, and that (irst through the influence of this chemical body the axone is enabled to make use for its nutrition of the material placed at its disposal in its anatomical course. Schiifer sees in the loss of the influence of the nucleus the importaiit factor in celliilif- iigal degeneration of a severed nerve fibre, but attempts no ex- planation of the nature of the nuclear power exerted.* Per- sonally, I rather favor the view advoc^ated by von Lenhossek, * To gain HI) idea of tlie recent eoiiceplions coneeriiing tlie relutioii of the nucleus to nutritive processes in tlio cell the article of Ilaberlanilt (Ueber die He/ieliunf^en zwisclien Function iind Liifi;e dcs Zcllkorns be! den Pflim- ■M'M, Jena. 1887) ami that of Kors<'iiclt, (Meitriifje z.ur Mnrplidloirip uud I'liy- siolofifie des Zellkernes, Zool. Jahrb., Abth. f. Anal.. Ud. xxvi, IHS(i) nuiy bo consulted. '»!il H lid / i \-']\ ^'' -i:. i: r '^1 f '[^ I -'1 1 1 ■ ¥ ' L 1 m 1 1 >: 9t i 1 P i ,1 ii 61 I t I, I! 308 TIIK NEIIVOUS SYSTKM. a^?miili^i: nij that instoiid of assuniin^ an iiotuiil triinsportation of a clu'iiiiciil 8iil),stajic(! wo can very woll conceive of a variety of excitation whicli, startin. Hut hy})otheses such as have just becTi considered will not suffice for the interpretation of the findings in the main body of the neurone after division of its axone — those included in the delicate experiments of Nissl, Flatau, Marinesco, Krlanger, and others, as well as those in the earlier studies of von (iud- den and his pupils, and in the observations upon the nervous system after amputations. We liave seen that these obser- vations have, partially at least, annulled the validity of W'al- * Itmiipf. 'I'll. Zui- Dci^iMicnitioii durcliscliiiitteiuT Xerven. Untersuch. u. (1. ])liysiol. lust. (1. I'liiv. llfidelb., lid. iv (1882). TlIK NKl'UONK AS TIIK INIT. 30U ler's (locrtriiio of the trophic ri'lationa of the norve cells, for after injury to iiii axone, in luldition to the dej^eiienition in tiio iixone peripheral to the lesi<»n, therc^ are (lemonstral)h' altera- tions in the (^ytoproximal end of the uxone and especially in tiie cell hody of the neurojie itself. Marinesco, in his careful study of the nervous system after amputations, attempted to account for the discrepancy. Al- thoufifh up to this time the spontaneity of nerve function had scarcely been (juestioned, this author threw doubt upon the autonuitic activity of tiie nerve cell. It was his idea rather that tlie functioiuil activity of a nerve cell was entirely depend- ent upon stimuli reaching it from the outside, and that in tlie absence of the a«lvent of external stimuli the spinal ganglion cells, for example, can not retain their nutritive functions. He was more cautious in his explanation of the atrophy of the ventral horn cells, but suggested that in case a limb was ampu- tated, eveji though the path carrying voluntary inii)ulses to the motor cells in the ventral horns remained intact, the one which l)rought the sensory impulses concerned in reflex activities was interfered with, and the dimii\ution in impidses reaching the ventral horn cells thus brougiit about could, he thought, result in a marked depreciation of tiieir vitality, (ioldsciieider, in ins article dealing with the do(^trine of the trophic centres, accepts fully this hypothesis of Marinesco and in a way extends it.* Von Lenhossck, who is favorably impressed by it, does not l)elieve, however, that the loss of centripetal stimuli reaching the corresponding segment of the spinal cord by way of the sensory fibres coming from the muscles, tendons, etc., after injury to a motor nerve,f will suffice to explain the alteration in the cells of origin of the fibres cut through. While 1 can- not agree with von Lenhossck that there is no physiological basis for the view that these stimuli influence the motor cells which lie in the same segment of the spinal cord, or that no reason for such a relation is visible, it must nevertheless be granted that in his attempt to offer a suitable explanation he has called attention to another possible factor which may be of decided import as regards nutrition. He finds the simplest ex- i /i * strong confirmatory evidoiico lias since been adduced by Warrington and van (M'huchlcn. Vide supra. f Cf. Nissl's experiments. ■ i! » -'il I, ts 'm < ' 310 TIIK NKRVors SYSTEM. plaiiiitioii of tilt' »l('jj;cMU'riitivo plu'iKiiiiciiii in quostion in tlio ussuiinitioii tiiat for I'vcry norvc cell a lu'Cicssary <'t»ii(lition of existence is its normal (fonnt'ction witli its end orj^an by means of its axonc — for exami»l(', in the case of a Oell of tiic ventral horn witii its corrcspondinj,' nuiscOc. In the ciittinff tlironfj^h of a motor axoni' it is, accord in<,f to him, not tlie h)ss hy tlic motor cell of the few centripetal stimnli wiiich this nii^dit occasion, but rather the impossibility of a normal dis('hartj;e of energy, the nerve cell being, as it were, end)arrass('d by the storm of excita- tions reaching it by way of the rcllcx collaterals, fibrils of the j)yramidal tracts, or other connections. Flatau, in his dis(;u8- sion of the sid)jeet, takes a nudway position, believing that the nutriti(m of the ganglion cell may be affected either by diminu- tion in the number of impidses whi(^h it receives or by the coii- sequent impossibility of the giving off of stimuli to muscles or to other ueurones. This certaiiUy is a very rational position to take, iiuismuch as in a society of cells, just as in any other commu- nity, if one member be dejjrived of the intlii- eiices of its fellows, or, although receiving such inthuMices, become glutted with them, owing to inability to dis- charge its own func- tions,that nu-ndu'r must necessarily sutTer. Still another hypothesis has been advanced by l^ugaro,* who has studied the alterations in the spinal ganglion cells after section of their peripheral (Fig. IH'.i) and central (Fig. 184) axones. lie points out that the motor axone and the peri])h- eral prolongations of spinal ganglion cells differ in that they are placed at the opposite extremities of nerve elements. This very position he suggests nuiy be of especial influence as regards ■ /5 '--'•.■:■'•;■> ."^ •::.:. i:^. •■ Vui. is:?. Si>iii;il jiiiiiKlidii cell sliowiiif; iiiiirki'd altcnitimis rulldwiiitr scctimi of the sciatic nerve. Siihlimate lixation ; tliioiiiii stuiiiiii^. (After I.li^'ari), ) * Lugaro, E, Sullc alterazioni dellc cellule norvose dei gangli spinal i, in seguito al taglio della branua periforica o eeiitrale dol loro i)rolungaineiito. Riv. di patol. nerv.. Fiivnzo, vol. i (18!)6), pp. 457-470; also, Sid coniporta- niento deile cellule iiervose dei ganglei spiiiali in seguito al taglio dolia branca eentrale do loro proluiigauieuto. Ibid., vol. ii (18i)7), pp. 540-543. TIIK XKUIIONK AS TIIK INIT. 311 (listiirl)iui('(M of imtrition. Ho thinks that either suppresrtiou of (he stiimili normally arriviiif; in tiie group of nerve elements or iiiipi'diiiu-nt to the (lisciiarge of energy from u group imts by (lis- .'^J»*'*{55r*'^ ^.i - turhing the nornuil uction of the •f'^^^i^L^'^^'^y:- he niiuU!OUt in the cell bodies in- side the spinal ganglia, after se(v tion of the fibres of the dorsal root l'"ui. IH-t.— spinal «aii«liiiii ii'll flirty iliiys ai'trr scctinii nt' rnr- n'S|Miii(liii}; iliirsil rmil. Siilili- iiiatr tixaliiiii: tliioiiin staining' ( Al'ti r l.ii^'ai'o. I of a spinal nerve or its intramedul- lary prolongations oidy insignifi- cant ehangt's or none at all are to be found in the (^ells. In order to explain this apparent paradox he suggests that the various elements of the nervous system offer varying resistance to nutritive disturbances. He can imagine that the sensory elements suffer more es})ecially from the suppression of external stimuli, while on the other hand the motor elements suffer mainly as a result of liindrance to the discharg(! of energy elaborated within them, and which, under normal circumstances, is removed immediately from the centre where this work is done. It is Lugaro's opinion further that the recovery of certain cells in the spinal ganglia and the pernument alteratiojis or complete disintegration of others is to be exi)lained by the assumption of variations in native regenera- tive capacity in differejit cells. 'I'hat the injury resulting from whatever cause, if only tem- porary, need not be fatal to the neurone concerned, is fully iiulicated by the general work which lias been done on regen- eration of peripheral nerves. P^ven though the preliminary signs of neurone decay can be demonstrated by the method of Nissl, the trophic function is not at first lost, inasmuch as strenuous efforts toward repair are made,* and should the axone * Tliis is a|)|)anMitIy triip ovimi iiisiilc tlie central iutvous system. Cf. WiiiTi'stcr, W. Ij., On ivcj^cncraliiin nt' Xcrve F'ibrcs inside tlie CtMitral Ner- vous .System. J. Xerv. timl .Mini. Dis.. N. V., vol. .\xv (1H) neurones the cell bodies of which are situated in the nucleus (lorsalis,Cha|i. Xfj; (r) neurones the cell bodies of which are situated in the gray matter of the cord, tlie axones going to the fascicu- lus ventro-lat oralis (Jowersi, Chap. XLI ; ((/) neurones the cell bodies of whieh are situated in the gray matter of the cord, tho axones going to the fasciculi proprii. Chap. .XMI. 2. Those pertaining to the cerebral peripheral sensory neu- rones — (o) Neurones the cell bodies of which are situated in 313 >* • • 1 I 1 1 11 1 - ■■■ :, li ^0i ^TT M :' I .ni ttiillili Ml m !'i :l| 'Mi Till", NKUVOI S SVSTI'IM. III!" iiiii'li'i Iciinmiilo iif till' N. Mijjtis, >'. >,'lii'.>.(i|ili(iryiii;iMis, III II I N. inll ci'll Itiiijii's III' wliirli nil' sjliijilnl III till- I'l'ii'lii'lliiMi, ilir iisoii:"' III' wliii'li run riTrlinilwaiil, iiiul pll>.^jll|y rcprc-i'iil an inilii'i'rl rriilnil ■-riiMii'v riiiiiliii'tiiiii plllll, ( 'iKIp. \l,\'l. I. ( 'I'lllllll M'llMirN ll\ii||i's |iil-.-.i|iL; llitiml' llirmi^li till' ri'i'i'liral pi'iliinrli' hihI llir li'i'iiiiiiiilii>ii>- uI' smli lixoiit's (iM 'I'lii' li'iiiiiiM'iis 111- lllli'l, Chap. MAM; (/>) iIh' fttsriciiiiis li'ii;;iliiiliiiiilis iiii'il Jali-<. Cliap. XIA'III : (i) lln' rnniialjn rrliniliiri'* allia, I'liap. NI.IX; («/) irrliiiii IIIhi'n nl' I III' liiai'liiiiiii ri'iijiiiii'lix iiiii Mini I III' Till Hal inn-- nf llu' ii in 'In is niliiT. Chap. Ii. ."». Ci'iitiiil si'ii-,.ir> asuiii's pa>>'-iiiy: lliii>iii;li lln> iiilii'iial capsiili' (I'lirlirupclal priiji'i'liuii iiriiiniii-- uf Ilir p'lii'ral si'iisory piilli) — (a) Kniliryi>h>Ki<''il syslnn Nn, I ; (/d i'nilir\i>liij;iial --ysloiii Nn. 'J; (/'\ I'lnliryolnyii'iil sy-lriii N'n. It. Chap! \.\. H. Ci'iiliiil nriii'i'iii's of ciiiiiliiit inn paths I'lirrt'spiiiiiliiij; In tin' I. Ct'iitiiil iii'iirnii -f I II' un- orj;aiis uf spi'rial sen lalnry I'liiiiiiiitinii path; 'J. Ci'nlr.'il nriirniii's uf llu- olfai'inrv iiiliii'tiKii path. Cliiip. 1,11 : :t. Ci'iitral n .ft ('iiiiiliii'tioii path. Chap. 1,111 ; I. Ci'iitiiil iii'iiii'iii's o aiiiiitnry I'Kiiiliii'tiiin palli, Chap. I.l\'. II' \ isinl I' I hi Srn>i:rriiiN III. Ni'iiimiii's liiri'i'llv roniu'i't ins,' tin' I'rn tval nrrvniis svsii'in \vi th till' voluntary iiuisi'lcs uf i hi' limly (lower motor iii'iiroiii's), .\. Tliosr pi'ilainiiii;- to Ilir s|iimil I'oril. Chap. I,\'. H. 'I'lioso portainiiii; to tlu' rhoniln'iu't'phalon, isthmus, ami in<'si'iiri'ph.'i'"ii — 1. Thosi'. till' axoiii's of whii'h lirloni; jo till' N. h iviioiriossu .'ii'i'ossoruis 'J. 'I'hosi', till' axolli's of wliirh ln'loiii; to I hi' ;i. Thosi'. lit.' axoiu's of whii'li lu'loin; to t hi' N. vaj;iis I't ijlossoph.'iry iii.'1'iis : -1. Thosi', llii' axoiii's of \\ liiih lioloiijl to till' N. farialis; T). 'l'liosi>, tin- iixoni's of wliirh lii'loiii: to till' N. .'iliijuri'iis : fl. 'I'hosi'. tlu' axoiii's of whii'h lii'loiiir to till' N. tii:;i'miniis Tl lOSI', Ihl' ilXOIll'S o r whi, lieloiiij to tho X. troi'hh'aris : S. Thosi', tlu' axoiii's of wliirh hi'loiiij to till' N. oiiilomotorins, Ch,'i|i. I,\'l. MUsKiT ION IV. Xt'uroi ii's wliiili oiiti'r 'iilo iiiiiurtion ri'latioii with il lowi'r motor iii'urom's ami throw thi> lalti'r iiiuli'r llu' inlliu'iiri' of oihor I'l'ii Iri's (iiiti'rmi'iliary ami uppor niotor m'iirom>s). .\. Thosi', I ho axoiii's of whii'h lu'lji to imiki' up I hi' fjisrii'iili proprii of tho sjiiiial oonl. Chap. lA'II. H. T tin' axoiii's of whii'li run in tin- fa iiliis lonuitmli nalis iiu'ilialis ami in tin' format io ii'tioiilaris alli.i of th rhonilii'ni'i'plialoii. Chap. li\'lll. C. T lOSl', till' -11 lioili I'S 111 Willi li !iri' sitiiatoil in lln' I'l-n bolliim, Chap. M.\. (IK'ul l'IN(i ASH CIIMNINO ToOK'niKU oh' NKWUONKS. ;{|r> |). 'riiiHc, III!' I'i'll liiiilirs iiT wliich nw siliinti iixhiii'n nf wliicli run til till' llloliir IIIM'li'i nT Ihr I'lTrlllui ni-I'Vrs, ('lm|i. liXJI ; U. 'rili)' hxihh's of wllii'll riirri'M|iiiiii| In llir li'iii|Miriii t'i'rrlii'ni'iii'lii'ii|iunlii| |illlll : ''t. 'I'lmsr, I III- iixnili's or wllii'll rniiiiril. Ilir Inliiis nrci- pilaliM Willi III!' inirii'i jjovrrniiij; lln' iiiovi'mciils nf I hr i-yi-M; li. 'I'linsi', till' ilxnili'S nf wllii'll rnlitii'i'l I ||i' rllitli'liri'|illlllnn Willi till' InWCr niolnr IH-lllnlli's, ('iiii|i. I,,\l\'. Si ' IIS Ki Tins \'. i'l'iiji'i'liiili llclirnlii'H, collllllissiiriil lii'lll'olics, illlii iismii'IiiI if ill IHMirolirs nf till- li'li'liri'|illllliill. A. I'rnjri'l inn iii'iirniii"-, ( 'Imp. L.W. H. ('nllllllissi:'"' iii'iilniii'H : 1. 'riinsi', liic llirilllljlllni llXniii'snf wllirll I'nrri'spninl In llii' tliiic'M nf llii' I'lirpiis I'lillnsir ; 'J. 'I'iinsi-, I III' llinlllllilli'il llMiMi's nf wllii'll rnl'i'i'spnnil |n |||(> ('niiiMiis.Hiiriv luilrrior coiTliri ; it. 'I'lmsi', Ihr iiiiKiiiiiult'il llXnIII'S nf wllii'll I'nlTl'SpnlKJIn Mil' lillll'siif | ||i IIIIMlMSIiril ilippni'HIIlpi, CilMp. li.W'i. ('. Assni-illlioll llOlll'OllfS: I. 'riliKc with slimt lixmii's; 'i, 'i'lin-;i< wit ll Inn;; nxniirs, < 'hap. Ij.W'II: -S. Iinriili/.iil inn nf iissnriii- tinli lii'lll'niii'.s ill till' crlrldlil mitc'X. l'"li'i'l|si;;'s linrt rilll! of "iiasociiitioii ci'iitn's," Chnii. li.WIII. (ii.\i"ri:ii ,\.\vi. [N'l'UdlUCI'OllV Mi'lhnils nf iji'script inn — ('lussiticillinn tn ln' rnjlnwi'ii Al'i'lliti'l'tilllics nf tll« iicrvniis sysli'iii— NiMirmu' systrms — Cnniliii'linn put lis, ] Onm would like lo he iihic to dcHCirilic tlic struct urc of tlic liiiiniin nervous syslciii accofdiiif^ t:o tlic iirniii^^cuicnt of tlic iiciifoucs iiiidcrlyiiifjf the Viirioiis fiiiietioiiid nervous pnxtc^sses. rnfortuiiutcly, the limited knowlcdiji^ we haw at present siif- lices only for a I»e;,'iniiin body. i\) Ixirrow an illustration from von Lenhossck, the i)eripheral nerves care for the "import" and " export " relations of the central nervous system, while the neurones inside look after " honu' " relations. In the fol- lowing at'C(»unt, therefore, it will be nec^^ssary to consider tin* structural relations of the neuroiu's which coniu'ct the sense organs of the body with the central nervous system (imdud- ing the afTerent nerves), of those connecting the central nerv- ous system with tlu' muscles of the body (including the etTerent I * Edinpor, Tj. Vorlt'suiifron tiobcr dcii Rau dcr norvoscii rotitnilortrinii' lies Monschcn iiiid dor Tliit-n- fiir Acrzle mid Studirciide. 5. Aull., Lcijiz.^ 1H!»H. :t!»H p|).. Hvo. (IHoriMNCJ AN'I) (MIAININ(i TodKTIIKR OF NKIKON'KS. HI7 m]^^fi nerves), im\' and LN' 1. 1\'. .Neurones within the central nei'voiis system which enter into conduction relation with the lower motor neurones and tiirow the latter under the iiithienco of other centres. Neu- rones eonnectinjj the pallium, cerchcllum, etc., with the lower motor iH'uroncs. Chaps. IjVII to LAIX'. \. Project ion, commissural, and association neurones of the telencephalon. Chaps. LX\' to liXN'lil. .\n idea of the t<'ctonics or arciiitecturo of tlie nervous .sys- tem, coMsiderinn' the neurones as the architectural units, can he j;ain<'d only when we foriii spatial conci'ptions of thedistri- hution of the various neurones and their processes in the cen- tral and peripheral nervi' organs. Such spatial conceptions are ohtainahle only hy comhininfi; in the mind the results of a whole scries of studies — emhryolo;4ical, histolouical, physio- logical, antl pathological. A careful study of the topoj^raph- ical relations in faultless sets of soriiil sections throuf^h various dejifeneratcd nervous systems, or through the fo'tal (ientral organs at various stages in the process of myeliuization, together with the study of (Jolgi preparations, permits one to make mental fusions of the single. [)ictures, and so to ohtain an idea of the distrihution in space of the various lihre hundles, and the cells of which they represent the niedullated axones. .V much more aeeurate method is tl':it of graphic reconstruction from serial sections {W . His), 01 plasties reconstruction hy ^^ #•..»• ! €. I i / T^ i I I' \i 'i^ [ i i : i . * J, 318 THE NERVOUS SYSTEM. means of wax plates (G. Born). The advantages of the latter method are illustrated in the model of the rhomheiicephalon and mesencephalon constructed by Miss Florence Sabin, to which references are occasionally made in the following chap- ters. If he has not obtained " ideas in three dimensions " of the groups of neurones and their interrelations inside the cen- tral nervous organs, the student will find himself entirely at sea when he attempts the explanation of the results of patho- logical lesions. The term " system " is employed often by neurological writers, and unfortunately not always in the same way. It would seem desirable,* in accordance with recent German writers, to limit the use of the term " neurone system " to an aggregate of homologous inaxones, and to restrict the use of the term " fibre system " to a group of medullated axones of homologous origin and homologous distribution (as regards their collaterals, subdivisions, and terminals). Thus, for exam- ple, the neurones, the cell bodies of which are situated in the spinal ganglia, the central axones of which enter the dorsal luniculi of the spinal cord and terminate in its gray matter or in the nuclei of the medulla oblongata, together represent a great " system " of peripheral spinal centripetal neurones. This system is in turn divisible into sii/j-si/sfeins — (I) on the ground of myelinizution ; and {'2) according to the particular nuclei in which a given set of fibres terminate. Tlje fil)n's of the pyramidal tract represent a " fibre system," since ( 1 ) they are the axones of homologous cells in the cerebral cortex, and (2) they terminate in homologous regions in the spinal cord. Topographical study teaches that there may be a " mixing of systems" in given areas of a cross section. A given topical area in a microscopic section seldom represents an entirely pure " fibre system." It is legitimate, hoAvever, in topograph- ical descriptions, to give names <) fortiori to th? vjirious areas. Thus we speak of the " area of tiie lateral pyramidal tract " in a cross section of the spinal cord, although we know that in tliis area a few fibres other than those of the pyramidal tract * Cf. Tschormiik, A. rdicr den ci'titralcn Vcrlaiif dcr nufstcifroiulon niiitorstnuiglialuicii und dcrpii Bezichiinfjon zii dcii Hiilincii iiii Vordcr- soitonstratig. Anli. f. Atiat. ii. I'hvsiol., Aiiat. Abtli.. \aA\y/.. (1H98). S. 2!) 1-400. UK()UPIN(J AND CHAINING TOGETHER OP NEURONES. 319 exist ; and again we call a certain bundle in the dorso-latiTal periphery of the cord the fasciculus cerebellospinalis, or the dorso-lateral spino-cerebellar system, though we have good evi- dence that the fibres of this fasciculus are mixed, in places at least, with fibres not homologous with the spino-cerebellar fibres. A chain or series of neurone systems, constituting a function- jil unit of a higher order, may be designated a " conduction path " — the (Jermans call it a Lcitiingxbahn.* Thus the several " systems " following upon one another in a given " conduction path " may be spoken of as primary systems, secondary systems, tertiary systems, etc. In the general centripetal conduction path from the muscles to the cerebral cortex the peripheral centripetal neurones corresponding to the spinal ganglion cells represent a " primary system " ; the neurones of the next liigher order (whose perikaryons and dendrites are in the nucleus fu- nicrli ciineati (or nucleus funiculi gracilis) and whose axones run as internal arcuate fibres across the raphe into the opposite interolivary layer, and on through the medial lemniscus to ter- minate in the ventro-lateral part of tlie thidamus) represent a " secondary system " ; while the neurones connecting the ventro- lateral part of tlie thalamus with the somaesthetic area of the cerebral cortex represent a tertiary system. This sensory " con- duction path" would consist, then, of three superimposed sets of " neurone systems." As we sliall see, in the " aiferent " or "centripetal" conduction paths the perikaryons and dendrites of a given "neurone system " are, as a rule, situated l)elow and the axones ascend toward the perikaryons and dendrites of the next neurone system. On the other hand, in tlie " efferent " or "centrifugal" conduction paths the perikaryons and den- drites of a given neurone system are situated, as a rule, alxnr^ and the axones descrni/ toward the perikaryons and dendrites of the neurone system of the next order. To use a nomencla- ture suggested by Tscherniak, the efferent conduction patli is composed of " distal-axone " systems, and the afferent conducticm path of " central-axone " systems. The " distal-axone " systems are in the main motor or reflex, the " central-axone " systems, in tlie main, sensory. *rf. Held, IT. Arcli. f. Anat. u Physiol.. .Anah Abtli.. Lcipz. (1893). S. 4;?(), Also till- nmiierous imblicutioiis of I'mil Fleelisig and ot VV. vou Hpohtercw. ■tV" I ri! 11" ■L- .. , I y f 'I f I 'J i iiNlJiifef m ;< ^ ; H 320 TlIK NERVOUS SYSTEM, III a given conduction patli, composed of aevoral superim- posed or subimposed neurone systems, tlie primary, secondary, and otlier systems need not necessarily contain tlie same total number ■^f neurones ; indeed, as we have seen already, and shall see furi'ier on, a single neurone of one system is often, by virtue of a number of end-rauiilications, able to enter into conduction relations with a lunnber of neurones in a neurone system of tlie next higher order (e. g., terminals of N. trigeminus in the sub- stantia gelatinosa, terminals of tractus opticus in the colliculus superior) ; in other instances, on the contrary, the terminids of a large nund)er of axones-of one neurone system may be so arranged that tiiey can influence only a snudler numl'cr of neurones of a neurone system of the next order (e.g., Nn. olfactorii, terminating in the olfactory ghmieruli). in t'.<' one case there is a "■ multiplication of elements " in the direction of the conducting path, in the other a "reduction cf elements." * To a description of the various neurone systems, at least those that are best known, wc nuiy now conveniently proceed. * For further interesting considerations of a similar nature witli regard to neurone systems and eonductiim piitlis. especially with refciTiice to tlie (lircn/i'Hcc and ciiiiHiieiicc of paths, the reader may turn with advantage to the article of 'rsehenuak above cited. SUBSECTION I. Neurones Connecting the Sense Organs of the Body with the Central Nervous System (Peripheral Centripetal Neurones ; Sensory Neurones of the First Order; Sensory Protoneurones). CIIAl'TER XXVII. 0\ TIIK OLASSIKICATIOX OF SKNSOKY I.MPKKSSrOVS AND THE KKLATION' OV TUK CKXTKl I'KTAL MU" HUNKS TO TU K SK(}- MKNTATIOX OF TlIK BODY. Neurones t'olleetiiij; Ijoilily impressions — Nouroni's collecting impressions from the external world — Kxternaliziition of im|)ressions — The neural sej^ment or ucurolouic — N'n. spinulcs — Uiidix vcntralis — Riiilix dorsalis — Ganjjlion spinalc — I'criphenil nerves — Rami communicantes, ete. — Plexus eervico-brachialis — Plexus lumbo-sacralis — Cutaneous distribu- tion of peripheral sensory nerves — Cutaneous distriliutioii of dorsal root fibres — Experimental studies in animals — Overlapping— Clinical studies on human beings — Surface areas of tiie topographical aiuit(jmists. Thk peripheral centripetal neurones are those through which the central nervous system is affected, (rr) by clianges taking phice in the body itself (outside the central nervous system and organs of special sense), and (/») ])y ])hysical and chemical influences exerted from the environment of the in- dividual.* This classification of sensory neurones conforms to the custom of dividing the impulses which pass into the central nervous system into (X) impressions which (M)ncern the body itself, and (B) impressions which concern the external * In this connection it must not be forgotten that the neurones within the nerve centres can be and often are very significantly alTected by infiu- ences de|)endont upon alterations in the blood aiul lymph. It wo\ild be a grave error to assinne that all the ph(Miomemi in the central neurones are dependent upon reactions called forth by impulses coining in through the peripheral centripetal fibres. The respiratory mechanism, for example, is largely of a chemical character. This, however, is so obvious when one's attention is directed toward it that further discussion here is unnecessary. -22 321 ^r: ir I ( : I li ' .:,■■! B^\iM 822 THE NERVOL'S SYSTEM. world, the former iiuliulijij; wliiit lius onliiiiirily been known as "■ <'oiniii()n sensation,''' the lat tcr cnibracin^ the "• special senses." 'J'iie tendency of tiie mind is to refer the sensations which may result in consciousness from the former sot of impulses to ohiinges in the body itself, and to project those whi(di result fr(»m tlie latter set of impulses into the external world ; that is to say, while the fornu'r are, as a rule, not " ol)jectivisable," or " externalizable,"' the latter are always or nearly always " ob- jeetivisable." In the latter set of impressions an element of externality seems to be iidierent. Such a distinction, while convenient for purposes of descrip- tion, is not wholly free from objection. In the skin, for exam|)k', one meets with a sensory surface which concerns not only the body itself, but also the external world. And even impressions brouiflit into the nervous system thron (/*) bringing impressions into the central nervous system from the organs of special sense ; namely, from (1) the gus- tatory organs ; (2) the olfactory organs ; (;5) the visual organs ; (4) the auditory organs. The relations of the sensorx nerve to the so-called neuratonn' or neural xajmcnt are shown in the accompanying figure (Fig. 185). If the student grasp clearly the idea of the neural segment (cf. Cha])ter Will) he will have much less difticulty in under- standing the archite(!ture of the nervous system in general. In the illustration the niotur rcntrtd vnol (radix ventralis) is seen coming out of the ventro-lateral surface of the spimil cord, being formed by the union of a numl)er of fila radicularia. It turns dorsal ward where it is joined by the dursal sensor ji roof {'.]) or radix dorsalis, in tlie course of which is seen a nodular swelling, the (/ini(//ioH sjtiitir/e (4). The ventral root forms no definite union with the dorsal root, but simply lies beside it, the combined roots forming the roininoii or ini.red iterre sfeiii (5). Tins common stem of a s])inal nerve divides into two main trunks, the rtn/nis tlorsitlis ((J), which runs dorsalward to su])ply the nuLsculature and skin of the back, and a ramus ventralis (T). Ill (iU()UI'IX(t AND ('HA1\IX(} 'nxSETIIPMl (>F N'KUHONES. ;52;3 wliicli turns vi'iitralwanl into tlio ])iiriott's to supply the niuscu- liiturc and skin of this rc^^ion, includinjjf the niuscuhiture aiul skin of the I'xtreinitios. This ventral ramus in ty])ical instances gives otl" {(i) a lateral branch, the so-called ramus culaneus Fl»).->. Fij;. SXi. ' I. tissiiia iiieiliaiia veiilralis id' {\w Npiiial coril ; /', sulcus iiiediaiuis doi'silis ; .^ radix veiitralis i motor i : ..'. radix dorsilis > sensory ' ; .J, jjaiifilioii spinale : -7, n<'rvus spinalis iconiuupn trunk i ; (i. ranuis tliirs;ilis : ,', ranuis ventralis ; ,s. ramus commnnicaus : ;/. ranuis ni rami vcntnilos iiiiicr- Viitt> tilt' wliolf of the vt'iitral iiuisculiiturc, iiu'ludiiig the iiius- ck's of thf superior ami inferior extreiuitiivs. Via. lS)i. — Plexus cfrvicD-linicliiMlis. i At'lor V. Kislcr. rrniii Rmilicr's tcxf-book.'l Vilitval view. /i. ncrviis liyiiiitilnssiis ; tlli, riiinlls ilisci'iiilciis liypo^jliissi, \ i'll I ill 1 * n »> . »», I n I * n.-» 11^* 1" 'ii M '^^iir. , II If , I )i III ii.^ 1 II .->» I nm n.-« ii^v |i> '^ i< '--.-• i, wliicli, aloni: with dr. tlic raiinis (hsi'cnilciis ciTvicalis. tonus tlio ausi liyim- tiliissi : (iiii, N. occiiiitalis miiuir : mi, N. aiiiiiiilaris nia^'iiiis ; sir. N. cutaiH'iis colli: (I, to N. actcssorins ; spr. Nil. siiiiraclaviiulaivs : p.S. iiliniiicus ; ils. N. (loi-siilis scaimliv ; n/is N. siiimisi aimlaris : nn, Nn. suliscaiiiilarcs ; nc, N. sulH'laviiis : n.r. N. axillaris: <•(!, N. tlioraio-lirailiialis : A", N. nulialis: we. N, niUMiilo-tiitaiiciis : .1/, N. iiitMliaiuis : In. Nil. tlioracalcs vnitrales : II, N. thorai'alis latcnilis ; l\ N.uliiaris: cm, I{. i iitancus iiitilialis ; ci, N.i'UtaiK'Us iiit'dialis : ill, N. intorcosto-bracliialis. In addition to the main division of the mixed or coinnioii nerve stem into a ramus ventralis and a ramus dorsalis, two (IHori'INMi AND ("HAININCJ TOOl'VI'IlKIt OK NKl'IMNKS. ,'^25 other rami arc j^ivcii oil" from this mixed trunk, namely, the runnis rinnininiinnis (H), containiiif? iH>th sensory and motor fibres (h'stinetl for the viscera and hiood-vessels hy way of tiie sympathetic nervous system (10), and a riinins i/ii')ii/i;/riis (U), wliieh runs hael< throu;;!) the f(»ramen intervertehrale to enter tlie vertebral canal, there to break up into fibres, which are dis- tributed to the spinal cord, its sheaths, and the walls of the vertebral canal. it would be a mistake, iiowever, to leave the impression that in each /wn'/t/imtl iirrir there are sensory and niotor fibres correspond in, ramus mns- eularis to M. iliopsoas: ('i\ N. I'emoralis ; mi. N. olilnratorius aecessorius ; <>, N. ol)turate (|uite diU'erent from tiiat met with in lesions of a dorsal root of a spinal nerve. Finally, lesions of the intramedullary continuations of the dorsal roots, owinj^ to deviations in the paths followed hy individual l)undles arisin}^ from a f,Mven root, will yield disturbances in sensation (|uite dilTerent in distrihution, aiul probably also in the (|ualities of sensation interfered Avith, from those met with in any extramedullary lesion. The cutaneous distribution of the j)eripheral sensory nerves has been tolerably carefully worked out by means of (1) dis- I'lii. 1S8. Tlic ureas siipiilicd l)y tlic cutaneous nerves of the head. (After F. Merkel, tak<'n from Kauber's text-liook. ) sections on the dead, {'i) experiments on living animals, and (:5) clinical observations on diseased human bein<;s followed by careful post-mortem examination. In I^'igs. 1* n 11 .\ s ivu l'"l(i. IWI. Anns sni)iili((l by the ciitaiicinis nerves of the ni)i)er extremity. (AI'terA. IviinlHr. I.ilirlilieli dtr Aliiitoliiie des Melisclieii, \' . Ailll., Jicip/.., IHitM. 15(1. ii, S. {S'M. Ki^. rvtlt. > A, volar siirl'aie ; I',, dorsal siirfaee. kc. Nii, siipracliivieiilares : iix. \. axillaris ; cm. N. ciitimeiis hracliii iiiedialis ; c./hci/, N. cntaiieiis aiitilinicliii inedialis; c.iiifd' . area of upper arm supi)lieelirl)iulitler.\natiiniie .. X. eutaneiis fenioris posterior; .w., N. sapheiius ; \i.r., lateral, yt.m., liraneh of N. |ieroiia'iis to the lef; ; .vH., N. siinilis; /)..>;.. N. peroiui-US lis ( N. eutaneiis dorsilis niedialis et N. eiilaneus dorsalis inleriiiediiis I't ales dorsales pedis) ; >)./(.. N. peroineus profundus • Nil. dinitales dorsali's- atenilis et difiiti seemidi iiie- })lied mechanical and thernnd stimuli to the skin. He came to the conclusion that in the skin of the fore-limb the fields of the individual spinal nerve roots more or less overlap one a .. I, * IMix, M. Expi'iiinentfllo Heitrage ziir liosiiiijj dor Fnige u('l)er (iie speeifischo Knorjjie der Ilaatnorvi'ii. Ztsclir. f. Hidl., Bd. xx (1H84). S. 141. f (idldschcidcr, A Oesainineltc Abliaiidliingcii iichordie Physiologic dos Muskelsiniips. Leipz. (1898). t von Frey, M. Beitriigp zur Sinnpsphysiologio dor Tliiiit, i, ii. iii, iv, Fieipz. (18i)4-"97). Aus den Hcrichirn dcr matli.-phys. CI. d. 1<. Sachs. Gcsciisth. dor Wisscnsch., .Tidy 2 and Doc. .1. 1894, ^Farch 4, lH9r). and Aug. 2, 1M97. .Mso, Fntcrsiichiuigcn uchcr die Sinnosfunctionfii dcr ni(>ns( Idichcn Hunt. Erste Ahhandliuig. I)ruci<(Mnp(indiing un. I Poyor, .T. I'ohor die poripherisclion Fndigiingen (h>r inotorisclien iind SL'nsil)ien l-'asorn dor in den I'loxiis hrachiidis des Kaniiioiioiis oiiitrotondon Nervenwurzehi. Ztschr. f. rat. Med., Ileidolb., 2 li., Bd. iv (1854), S. 52-77. (illOUlMNG AND CHAINING T()GI<:TI1KH OF XEL'HOXKS. liSl another. lie iH'licved, liowcvor, that the territorv innervated hy a sensory «h)rsal root corresponds approximately to the skin Avliich covers the muscles innervated hy the corresponding motor ventral root. The adnurahle researches of Krause* show how much can l)e done hy simple dissection and dissociation. Krause also used the so-called reflex method and followed hesides the degeneration of nerve fibres after section of the nerves. His studies are of great importance in the history of localization, and must be carefully considered by every one investigating in this field, llis conclusions regarding the iiftii, sixth, seventh, and ei hth cervical roots in the main still hold. A very important contribution to Icnowledge is to be found in the research of Tiirck,f who worked out in detail the areas ',th thnrnt'ir .ST. ''son/ skin field. jiiiiimimuiiiiiiiiniimiii ,\\\\\\\\\\\\\^^\\\\\\\\\\\\s\\\\\t^ llimdcic. r.th thoracic. Vui. l!tl. DiaKnini of the position of tlic nipiilc in tlic sensory skin flol.ls of tlic nil. M. iin'l 5111 'loracic s]iiniii roots. Tlic ovciliippinf; of the ciitiincoiis areas is represented, i .\fter (;. S. Slierrinjiton. I'iiil. Tr., Lond.. 15.. IsilH, vol. elxxxiv. ISltt, p. *:{*.) for the spinal nerves in the dog from the level of the fourth cervical to that of the fourth sacM-al. His results are very nearly in accord with those of the more recent studies, and it is rather curious that they liave not attracted the attention of 4iiuitomists in general. This appears to be due in hirge part, * Krause, W. l^eitrU^e zur systeniatisclien Xenrolnijie des inensclilielien Arnu's. Areli. f. .\nat.. I'liysjol. u. wisseiisrh. Med., I.eipz. (1H()4|, S. ;!4!)- J{.')7. — npitniLrc zur Neur the ditticulty of understunding the experiiiK'iital notes and drawings left by Tiirct;, and pub- lished postluiniously. Tiirek made out distinctly the bandlike areas of distribution, but ])robably went too far in stating that each spinal nerve lias an area of skin belonging to it, which is sui)plied l)y it exclusively, lie recognized, iiowever, that many of the spinal nerves have a field whicli they supply in common with some other spinal nerves, and he even made out that the nerves of the upper and lower extremity have no exclusive areas but only common ones. Of the recent studies may be mentioned those of Walsh,* llerringham,f Paterson,;); Sherrington,* and others. Sherrington's studies are most painstaking and elaborate, and include ex])i'rinients uj)on a large number of frogs, cats, and moakeys. He proceeded as follows: Finding that section of a single root did not cause complete ansesthesia anywhere, but only a diminution of sensation, in order to determine the exact peripheral area of distribution of the dorsal root of a given spinal nerve he cut two or three roots above and below the root in which he was interested. Thus, to determine the area of distribution of the fourth thoracic root he would cut the second and third thoracic roots and the fifth and sixth thoracic roots, while to determine the area of distribution of the third thoracic root he would cut the first and second tho- racic roots and the fourth and fifth thoracic roots, and so on. The zone in which sensation silil existed could be determined by testing for refiex response. He foujul that the field of skin belonging to each sensory spinal nerve root overlaps the skin fields of the neighboring sjjiiud nerve roots to a remarkable extent. " The disposition is such that the field lajis to a certain extent over the field of the root or roots iiiimediatelv in front *Wiilsli. .1. Till' Anatomy of llic Mnicliial Plexus. Am. .1. .M. He, Pliila.. II. s.. vol. Ixxiv (1H7T). p. :iH7-*iS)\K t IIcrriiii:li,im. \V. I'. The Minnie Anatomy of the I^rachial I'lexns, Prop. Roy. Soc. I.ond.. vol. xli (IHH(i). pp. 4M-441 : also Phil. Tr. Lond,, clxxvii (IHHT). I Patcrson. A. M. Tlic Oriu'in iiml l^istrilmtion of llic Nerves to the Lower Liml). J. Anat. and Physiol., iiond., vol. xxviii (18!);J-"!»4), pji. 24: ir.'t. ** Slierrinf,'ton. (". S. Kx|ierimenls in Examination of the Peripheral Hist riliMt ion of the i-'ilircs of the Posterior K'ools of some Spinal Nerves. Phil. Tr. liond.(M) for the Year 18!):!, vol. elxxxiv. Loiid. (1H!M). pj.. G41-76:\ GROUPIN GliOUPING AND CHAINING TOGETIIKIl OK NEURONES. 333 of it, and to a certain extent over the field of the sensory roots immediately behind it. These two overlaps may be termed respectively the anterior oirrlap and the jxhsieriur overhij) of a sensory root tield " (Fig. 1!)1). Sherrington further finils that although in a plexus each spinal nerve root aifoi'ds separate contributions to several nerve trunks, the cutaneous distribution of the root is composed not of disjoined patches but of patches so connected with one another that the distribution of the entire root forms a con- tinuous field. When at its simplest, as in the thoracic region, the shape of the cutaneous field of a dorsal root is that of a horizontal band with almost parallel edges, wrapping half way around the body between the mid-dorsal and mid-ventral lines (Figs. 192, 193). This simple zonal shape is departed from in maiiy places, owing probably to the modification which the l)0(ly segments have individually undergone in tiu^ development of the con- figuration of the animal. This deviation from the simple and regular figure is due in vertebrate forms largely to the out- growth of the limbs, but with care the root fields can be toler- ably accurate! defined in the upper and lower extremity. Here the zones can approximately parallel to the long axis of the limb, which is not surprising when the mode of origin of the limb in the embiyo is coJisidered. Reflex rea<;tion is much less easily elicited near the edge of a field, in Sherrington's experiment, than in other parts of each spinal field. In addition to the (inferior overlap of a sensory spinal skin field into segmejital fields anterior to it and the posterior over- lap into fields posterior already mentioned, each one of these fields has rro.s'sed orer/aps passing into the fellow field of the opposite half of the body, both at the mid-dorsal and at the mid-ventral line. Since the fore and aft overlaps are very marked, Sherrington concludes that each point of skin through- out the body is supplied l)y at least two sensory s])inal roots, in some regions by three. Sherrington denies that the cutaneous fields of the sensory spinal roots correspond closely with the fields of distribution of the motor roots in the skeletal muscles. He states further that the sensory spiiud fields do not corre- spond with the fields of cutaneous distribution of the motor root as judged of by the pilo-motor fibres of those roots. On i ',i?pi ■i? i ■ ! ill I'm. Id'J.— -( 'ul:iiic(iii> tii'lil - iiI'ddrsMl riHii> ni -.pin;!! nci'Vr> nf niuiiUcy. hursil vnw. I hi' aiilcricir hiinlii-^ (iT till' -kin lii lil> aiv niarUcil cm llic Id't IimII' cif ihc cast-.. Ilic |Mi>lrrinr iHirilci-- (111 llii' liuhl hair. ■ Al'tir ( . S, sluiiiiiytciii. I'liil. I"!., I.iukI,. isitj vol cIwmv. I'l. M.I r .■»;. 'fl %^ l! /I i 1 I 1: 1 1 Ki(i. l',i;5.^('iitain'ipiis (icids nl'ddrsil runts (if siiinal ncrvt's nl' inonkcv. \ iiitni-latcial vi (AIUt I'. S. Sluriiii^itiin. I'liil. Tr.. I-..ii(l., l.SD-J, vol. clxxxiv, I'l. M. i yits li 33«; TIIK NKRVOUS SYSTKM. the otlier hand, the i)ilo-inotor tiekls of the synip.ithetic ganglia and the cutuneous sensory fields do correspond. A more recent and apparently very extensive paper by Sher- rington I iiave thus far been able to consult only in abstract.* In this article Sherrington discusses, in addition to his experi- Fl(i. lilt. — Mode ofdistrilmtioii of the ilursil rout titirt's of tli<' lower corviv'al iind tlior.icic nerves. ( After W. Tliorl)urii, from A. van (leliueliten's Ansitoniie (111 systenie nervelix, etc.) mental studies of the distribution in the skin and muscles of the Xn. cervicales and upper Nn. thoracales of monkeys, the results of some investigations which concern the N. trigeminus and also the behavior of the spinal reflexes in total transverse * Sliprriiigtnii. ('. S. T'lxpcriiTionts in Examination of the I'eriplieriil Dis- tribution of the Fibros of the Posterior Hoots of some Spinal Xcrves. Part IF. Phil. Tr. liond.. B. (1898), vol. cxc, i)p. 45-180. Abstr. by L. Briirs in Neurol, ("cntralbl., Lcipz.. Bd. xvli (1898), S. 1041-1040. r.rif ■ '' '. GROUPING AND CHAINING TOGKTHKll OF NEURONES. 337 losioii. 8horriiii)in<^." Electrical stimulation and studios of de- generated fibres by osmium blackening were also made. So far as tlie subject now being considered is concerned, the second chapter of his article interests us most — that dealing with the relation of segmentation to the innervation of the ex- tremities. On superficial examination one might be led to believe that considerable differences exist as regards the limbs in the areas of distribution of the motor and sensory roots of ^iven spinal nerves. The areas of motor distribution form con- I'"lS87-'H)^), pp. .'581-407.— .Spinal Local- izations as indicated by Spinal Injuries. Hrain. Lond., vol. xi (1888-'H'J), pp. 2H!)-3!24. — The Distribution of i'aralysis and Aiwcsthesia in Injuries of tlie Cervical Region of the Spinal Cord. Rrit. M. J., Lond. (1888), vol. ii, l>p. 1:582-1885.— A Contribution to (he Surgery of the Spinal Cord. Phila- delphia (1880). ■f Ross, James. On the Segmental Distribution of Sensory Disorders. Brain, liond., vol. x (1887-'88), pp. ;5:53-;{61. t Dana, C. L. A Clinical Study of Neuralgias, and of the Origin of UeHex or Transferred Pains. N. Y.Med. J., vol. xlvi (1887), pp. 121-127. * Starr, M. Allen. Local Ana'slhesia as a Guide in the Diagnosis of Lesions of the Lower Spinal Cord. Am. J. Med. Se., Phila.. n. s., vol. eiv (1892). pp. 15-;55; and Local .\na'sthesia as a Guide in the Diagnosis of Le- sions of the Upper Portion of the Spinal Cord. Hrain, Lond., vol. xvii (1894). pp. 481-512. II .Mackenzie. .1. Contribution to the Study of Sensory Symptoms Asso- ciated with Visceral Disease. Med. Chroti.. Manchester, vol. xvi (1892), pp. ^ Mead, II. On Disturbances of .Sensation with Especial Hcference to the Pain of Visceral Disease. Hrain, Lond., vol. xvi (189:5), pp. 1-133; ibid., vol. xvii (1894), Part III. pp. 339-480; and ibid., vol. xix (1896), pp. ir)3-27r). Koclier, T. Die X'crletzungeii der Wirbelsilule zugleich als Heitrag zur Physiologic des menscidichen Riickenmarks. Mitt. a. d. Grcnzgeb. d. Med. II. Chir., .Jena. Hd. i (189(5), S. 415-480. — Die Liisionen des Riickenmarks bei Verletzuiigcn der Wirbclsiiulc. Ibid.. S. 481-1160. 1 Cushing. llarvcy \V. Ha'inatomyclia from Gunshot Wounds of the Spine. Am. .1. M. Se.. Phila., vol. cxii (June, 1898). t;.. I !■ II II I , 1 /i I F I ; i ^r ':' 340 TIIK NKIIVOUS SYSTRM. Tlio paper of Ross is hriiiiful of sugifi'stivoncss, and should be read by every one who wislies to enter at all thoroujjhly Fi<;. HKi. — >rii(lc iil'distriluitiiiii (it'tlic dnrsil rnot lilircs of tlic Iuni1):ir and siicral iitiv<'s. lAfttr \V. 'riiiirlmrn, troiii A. vim (icliii followed delinite lines. Stimulated l)y the suggestive papers of Ross, he thought it prol)ahle that these areas nnght hear some delinite relation to nerve distribution, and with this in view studied the distribution of a large nund)er of cases of herpes zoster, hoping that they might throw some light upon the sig- nilicaiKie of the tender areas in visceral disease. To his surprise he found that the areas occupied by herjjes zoster corresponded exactly to those with which he was familiar in visceral disturb- ances. Further study showed that the areas represented the distribution of either a single nerve root or a segment of the spinal cord. Head inclines to the view that the distribution of the nerve roots is somewhat different from the distribution for the seg- ments inside the sj)imil cord. His reasons for thinking so are briefly these : Whereas Sherrington found that the areas of cuta- neous supply from any two roots definitely overlapped. Head states that his areas do not overlap at all, or if so, only very inconsiderably. Sherrington's areas, it is true, apparently repre- sent the root supply for the sensation of touch, while Head's areas correspond rather to pain sensations and trophic sensa- tions. It might be assumed that whereas the distribution of the fibres for the sensation of touch in the various dorsal roots over- lap considerably, those for pain do not overlap. Sherrington, however, states expressly that he nsed touch and pain stimuli indifferently as a test for the presence or absence of sensation, and Head feels sure from his observations in five instances of surgical division of a single dorsal root in man that not only was there absence of ana'sthesia to touch after division, but in most instances the sensation of heat, jiain, and cold was also not materially disturbed. Head believes, therefore, that where- as Sherrington's areas represent the true root supply, his areas correspond to the su])ply, not of roots, but of segments of the spinal cord from which the roots in ])art arise. He believes ^^1 ni n 4 .■■tUJElliK 1' 3 ''Mmiii! r* ii i I « iii'' L IMAGE EVALUATION TEST TARGET (MT-3) k^O <^>^ <^:#,%* A^ t-?. :/ 1.0 I.I 1^ 12.8 In ^^^* 163 u lit f ^ m Iii2.2 IL25 111.4 1.8 1.6 Photographic Sciences Corporation 23 WEST MAIN STREET WEBSTER, NY. !4S80 (716) 872-4503 1 \ \ c\ "% V ■^ '% V ^d 'o wk< -i W. Anifinia. Emloint'tritis. Bladdery Constipation <'nricH of incisor, Error of oyo-rofraction.,^ Gaptrir dyspi-pBia cured by acids. "' /_^ Decayfid teeth. -/,s are situated. Of the cerebral nerves not all possess sensory functions ; outside of the organs of spe(fial sense only those which are provided with ganglia in their course are known to carry centripetal impulses. Excluding the nerves of special sense — that is, the olfactory, optic, and cochlear nerves, and the nerves concerned in the sense of taste (portions of the glossopharyngeal, trigeminus, atul nervus intermedins) — we have left as sensory cerebral lu^rves the sensory portion of the nervus trigeminus with its ganglion senii- lunare (Gasseri), the nervus intermedins of Wrisberg with its geniculate ganglion, the nervus vestibuli with its ganglion ves- tibuli, the nervus vagus witli its ganglion jugulare and ganglion nodosum, the nervus glossopharyngeus with its two ganglia (gan- glion superius and ganglion petrosum), and occasionally, per- haps, a portion of the hypoglossus nerve, since in the embryo at any rate it is sometimes provided with a sensory ganglion (Froriep). In these various ganglia are situated the cell bodies a50 1^ Fig. "^ HI'S Fi/... IHlw, U(l. ii, S, 501. Kin. tsr.. ) I'. N.iviis triufiiiiiiilM ; ,\7/, ni'i'viis liyiiinjlnssus ; r,, ('h-nI ccr- viiiil iici'vc ; r .'-,s, sccdiid tiMiulilli ctTvical iicrvr ; T I I .'. tii-st tiitwiirtli lliiiracic nerve : /. /-.■;, lirsl \i> lil'lli liiniliar nerve ; SI .■;, (irsi tn til'tli sieral nerve; C, Nervus eiHcyKens ; x, .1, liliini lerniinale nf the spinal eiinl. Fnini the rcmt niarkeil I,, tn r, eanda eipiina ; llr, plexus liracliialis ; (V, Neivns feniu- ralis: Nc, Nervus iscliiadieus ; O. Nervus idilurato- rius; the enlarK<'nients oppipslle L '.i. I. and ."> rep- resent the spinal K^mulia mi the dmsal runts. On the left side iif tile IlKUre the s.ynipat lielie tnilik is sIkiwii. (I til -ix are naiiulia ; n, Kaii;;licin eervieale siiperilis : h and c, Kan^liiin eervieale niediiini et in I'eriils ; il, first tlmraeie tiiinulimi ; Ki. Fin. 24S. l A, spinal eord .seen from the ventral surface. On the ri^lit side the ventral tila radicularia have heeii cut through. H, spinal cord seen from the lateral surface. — /, ventral median tissure ; .,', dor.sal median sulcus: .;, sulcus lateralis veiitralis, whence tlii' ventral lila ra.dicularia emerne : .(, sulci laterales dorsales throUj;li which the dorsal root lilires enter the spinal lord: •''. radi.x veiitralis ^'linK !«ist spinal ),'anj;lion cut throiifjli on the rifjlit side in Fi^. .\ ; C. radix dorsilis enierKinn from the fian^dioii spinale (6" ) ; 7. N. spinalis immediatel.v after its formation throiif.'h the union of the i-.ldix ventmlis anil dor- silis dividing into 7. a ramus veiitralis, and <", a niniiis dorsalis. The ramus coniniuiiicans and tlie ramus mt'iiiiigciis aiv not shown in this tif^ure. It Hi TIIH NKUVOUS SYSTKM. of tlio peripluTiil sensory nouroncH, of the variety under diseus- sion, pertaiiiiiif; to tlie rhonilu'iiccplmloii. It is especially to be noted that, if we leave out those {^'uthered iroin the viscera l»y means of the sympathetic nerves, nil the impressions collected at tlio periphery of the body and !'■< ' III ■imim VlG. ~(lli. — Sclii'iiu' of pcriplicriil spinal sensory nciiniuc sliowinK tlic iicriplicrnl process, il, extending to a periplunil sensory surface /» and a central axoncc, enteriii}; the spinal cord tlu'oujili the dorsal root ofa spinal nerve there hiflir- catinjt at c into an ascen. 2.-), V\ii. ti. ) from the ijiternal organs are carried into the oentrtd nervous system (spintd cord and hniin stem) by means of one set of neu- rones (Fig. '2W>). The total number of individual neurones m 0I10UIMN(} AND ('IIAINM\(} TOOF/riIKU OK MirilONKS. ;{;-,;{ (•onci'nu'tl is ciioriiinus, l)iil there is no siiperiinpositioii (if m-u- ront's in the nu'chanisni hen- deseribed. A centrijx^tal impulse orijiijmtinf,' at tho periphery reuclies the primary end-stution of the sensory neurones insicU; the central nervous system after liavinj; passed throuj^h oidy one neuroiu". Althou^'h for the orii^in of any j^iven sensation centripetal impulses start at the periphery, usually in a considerahle nundjer of dilferent neu- rones, each of these extends as fur as some j)rirmiry end-station inside the (central nervous system, not requiring to puss through any secondary neurone on the way.* * Tiiis is ill all protmbility not Inm of the sensory iinimlsus collected l)y menus (if tile neurones of the synipiitlielic system ; tliese im|iiilses, it is prol)- aljle, puss tiu'oiiyli ii elmin or series of indiviilual neurones liefore urrivinf? in the cerebrospinal system. They are earried by means of ilie rami eom- iinmieantes into the dorsal roots of the spinal nerves. Theii' fiirtlier faie is not yet elear. Some of the synipatiietie axones end wiliiin the spinal ganglia ubont the l)0(lies of spinal ganglion cells, and the centripetal im- pulses which they carry coiilil then lie taken into the spinal cord liy nu'ans of the central prolongations of the spinal ganglion cells. It has liecn as- serted by some investigators that a certain numlier of sjmpalhetic axones jiass from the ranu eommunieanits directly through the ganglia, or past them into the dorsal root* ami so into the spimd cord without intcrruptitju. More research is necdeil before entirely satisfactory statements can Ije made regarding these points. V %.'■ Si iMilii CIIAITKR XXIX. a KN KKA L DKSCKI I'TIUN. Tlie s|iiiiiil piiif^liii — Hipolar cells in cinljryu — riii|i(iliir I't'lls in adult — IVriplu'riil scnsorv iil-ri's — Central axoiies to dni'sal fmiieiili — Fibres C'xogciu's of 1*. Marie — Nuclei teriiiiiuiles — I'liylotrenetie stmlies — The structure of liuinau spinal piujiliou cells — Studies of v(iii Leiiln^ssek, Lugaro, and N'issl. 1. Centripetal Nt/urones of the First Order (collecting Bodily Impressions) connected with the Spinal Cord. Tin; ])erikiiryon8 of all the sensory neurones that we are de- scrihiiig are situiited outside the central nervous^ system (ii\ human heincjs) in marked contrast to tlie cell bodies of the pe- ri])heral motor neurones, which are situated within thecoliimua' grisere of the spinal cord. In Section IV the emhryological orifjin of these neurones has been described. It will be re- called that in the human embryo they a])])ear near the spinal cord and soon come to occupy positions lateral from it. At a very early period the distal and central processes of the s])inal ganglion cells are recogniziible. It has also been pointed out that there is a gradual transition in the end)ryo from the bi- polar condition of the cells to the uuijiolar condition Mliich is characteristic of the adult. In considering the anatomical dis- tribution ajid physiological functii;ations run into the nerve centrer to end in the prinuiry end-stations or nuclei of termination of the (cerebral nerves. In the last are situated the cell bodies and dendrites of other neu- rones (of the secoiul order) which can take uj) the impulses and carry them further. While it is true that nearly all the embryonic bipolar cells of the spinal and cerebral sensory ganj^lia become later unipolar in Inunan beinj^js, in many of the lower forms, for example in the lish, they remain bipolar throu^ihout life. It is interesting to remember that in the ganglion vestil)uli of human beings (as well as in the ganglivyU cochlea') the bipolar condition is retained throughout life just as in the fish. l'hylogeneti(! studies have excited a great deal of interest 'n (ionnection with the original position of these peripheral si'U- sory nem'ones.* In some animals like Lnnihriciis the cell bodies of tlie sensory nenrones are situated in the epithelial surfaces of the animal (Fig. ^OS), the short jjeripheral process or den- drite passing between the other epithelial cells toward the sur- face, the central prolongation running from the skin into the nerve centres. Other animals (like 3Vvv'/.s) possess neurones in which the cell body is no longer located in the peripheral epi- thelial surfa(!e, but is situated near it, or at various points be- tween it aiul the central organ. Tlu' further the cell body from the epithelium, the greater of course is the length of its distal process. In human beings, as has been stated, and in other mammals the cell body is almost as far distant as possible from the i>eripheral surface, inasmuch as the spinal ganglia are very close to the central cerel)rospinal nervous system and very far removed from the peripheral sensory surfaces. One verte- brate, amphioxus, is peculiar in that its bipolar sensory neurones are situated within the s])inal cord (Retzius). There are ani- mals — as, for example, I'tcrnlrdrhca — which in a comparatively limited space show a whole number of transitional stages bt'- , ,^. * Cf. Uotzius. 0. I'eboi' dio iicucii Priii/i|iieti in ilcr lA'lirt' v(;:>). The ganglion spirale and ganglion vestibulare in hnnian beings present stages transitional between the peripheral olfac- tory neurone and the ordinary peripheral 'sjjinal neurone, since 5/- rni Fio. '.iOS. — rcrijilicriil (•ciitriiictal iiciinnics of viirioiis iiiuiiiiils. ("After f!. R«'t- ziiis. liiol. rntcrsiicli., Sti.ckliKliii, 15(1. iv, isit^, S. 5t). Kijts. I, •„>, :5. and 4.) .1, oliKiicliii'tii' woi'ins I I,iiml)riciis I : />', pulycliii'tic worms iNcrcisi; r, mol- liiscs ( Liiiiiix 1 : l>. vcrtchratcs. Tlic Krailiial cliaiiKc in llic position of tin- pcril\aryon in llic pliyloKcnctic scries is inlereslinj;. c. epillielial eellsof sen- sory surface ; c, cii'MMila : a:., periliaryon of periplieral centripetal neurone; )•(«, retc .Malpljiiiii « f epidermis ; sii. axone ; vii. central nervous system. the cell bodies of the neurones in these ganglia tire situated out near the sensory surftici^s, whence they collect impressions, though not iictually in them. The structure of the cell bodies situtited within the spinal ganglia has been described at some length in Section III and ■rw Ji l)er den Ban der Spinal.ViUijjlionzelh'n ties Meii- sclien. Anil. f. Psyeliiiit. ti. Xerveiikr., IJeil.. Bd. xxix (1896-97). S. ;i46-:380. f ('ava/./iini. E. liitorno ai gfinijli s|)in!ili. Arch. ital. di clin. iiicd., Mi- lano, vol. xxxvi (1S97), pp. 41 -o:!. X Ltiffaro. E. Siille alterazioiii delle cellule nervose del jjan^lia .spiuali. l\iv. di patol. iierv. e ineiit., Fireiizc, vol. i (1890), Nos. 8 ami 13. GROUPING AND CIIAIXIX(} T<)(;CTIIEH OP NKUIIONKS. 359 axont's roiU'li the pcriplu'nil or^'aiis, wlionco tlicvrolloct ci'llulip- etal iiiii)iilsi's. All of tlifso pcriplionil llbres uiul ircc ; tit uiiy rate, we have as yet 110 evidence of connection />// con/ in 11 if// of the termination of one of these fibres with any other cell. That m : i % ■■h\ ■fPm 7 A*.i.\ *» 1.* ■^ -I '^ <-'a' • C D /A<. ; . . .■- •^;v<;:^■••'■A;;i^.•:, •. . ., '^ :■■^•;^•■^:i!^^t:•v.v^/ ■^-^ ^^:^i 1/ IS^*:*^, '*-wi 1 ^./ ri(i. :JIO. — Scvcriil typi's of si)iiiiil j;aii;.'Iiiiii cells. lAI'lcc M. vmi licnlinssi'k, Aicli. r. I'sycliiiit., 15(1. xxix. lSilii-'!»7. ) .V ami T), small rlinimniiliilc spinal fiaiiKlinncclls, siimcwhat slirimkcii ; H, mcil i 11 iii-si/.cil spinal trail jil inn ct 'II with ciiars'' tiKi'did masses; it, piumcnt : (', larjre pale cill, perii)li('ral ;;arlan(l of titjriiid evident ; K, small ehnimnpliile spinal {ranulion cell, interidi" nt' eell jireseiits a lionio^fneous appearance, >;ailaml of tigroid masses at the pe- rii)iier,v. the pcriphenil endiiifjs may iictuiiUy i)onetrate into opitluOitil or other cells seems likely from the studies of Knjjfclmiinn, Ajjiithy, and others. The modes of ending in the peripheral organs are, liowever, very varitihlj. ji ;ii|iii|ii|i ar.o TIIK NEItVOrs SYSTEM. It WUK long thoufflit tlmt gimii cells were situated in Meissner's corpuscles in the skin, in the so-culled Tasfzcllfu of Merkel, ami in other peripheral end organs, and that these send their uxis-cylinder processes into the nerve (centres. Hut this view has been shown to be false. The peripheral prolongations of spinal ganglion cells end free in the shape of disklike ex- pansions in these structures. On account of their functional relations the so-called sen- sory nerve endings might be, perhaps, better called peripheral nerve beginnings. No less than one hundred and eighty-five articles concern- ing the endings of sensory nerves ii. vertebrates have recently been collected and reviewed by Kallius, of (Jottingen.* As this author states, the ditlerent varieties of nerve endings nuiy be classified in diiferent ways, either according to the eiulings themselves or to the tissues in which they are situated. They iiuiy terminate independently of any special end organ, or the free endings of the fibres may be inclosed in certain definite, specially ditferentiated, terminal corpuscles. The most con- venient method of describing them is as (1) those incident to epiblastic and hypoblastic structures, and {'i) those incident to mesoblastic structures. * Kallius. E. Eiuliguiigeii sensibler Nerveii bei Wirbeltiercn. Merkel Homiet's Erf^ebn. d. Anat. u. Entwickelungsgeseh., Bd. v. (1895). Wiesbaden, l8t)G, S. 55-94. ■ II! hi: CHAPTER XXX. THE MKDl LLATKM I'KKI I'll KKA L AXOXKS OF TH K IM'.HI I'll KUAL I'KXTKIPKTAL N' KUKON KS AND THKIK TKKMINAL A IM'A UATIS. C'eiitripi'tal lu-rvc eiidiiif^s or beginiiiiif^s — ("Ijissiticutioii — Xorvt; hcgiiiiiinj^s ill ('I)il)lasti(' and hy|M)l)l)islic' tissues — Naked bcginiiiiiKs i" I'pitlit'liuin — Kpidcriiiis — Mucous ineinbniiK's — End-platelets — Merkefs Tastzellen and Taslnienisci — (irandry's eorpuscles — Nerve beginnings on hairs, hair follicles, and teeth — Nerve beginnings in lung, liver, pancreas, stom- ach, and intestine — Nerve beginnings in niaiuniary gland. Sensory Nerve Beginnings in Epiblastic and Hypoblastic Tissues. Is tlio skill tlu> fibres representing divisions of peripheral prolongations of spinal ganglion cells lose their myelin sheaths before entering the epithelium. Once inside the epidermis, they branch typically, giving off first tangential brunches, from which secondary finer divisions pass through the stratum ger- ininativum into the up])er layers. The individual fibrils can pass upward or downward, l)ut always, or nearly always, end in the epithelium itself. At the tips of the individual fibres very fine bulblike processes are often seen. Many believe that the nerve fibrils end inside the epithelial cells. Certain it is that the nodules can lie seen pressing into the surface of the cell, but that they actually are to be coiisidered as intracellular nerve endings is at present doubtful. The weight of evidence is, on the whole, against this view. In mucous membranes covered by squamous laniellated epi- thelium—for example, the tongue and oesophagus (Fig. 211)— the relations are similar to those in the epidermis. Retzius * has pointed out a peculiarity of the terminals of the nerves in * Rotzius, G. Ueber die sensiblen Nervenendigungen in den Epitlielien hei den Wirbelthieren. Biol. Untersuch.. Stockholm, n. F.. Hd. iv (lHfl2), S. ;57-44.— Kinigc IJeitriige ziir I\<'iintniss der intraeiiitholialen Endigungs- weise der Ncrvcnfasern. Biol. Untersudi.. Stockholm (1894), n. F.. I'.d. vi, S. 62-64. 361 1;' ,1 IB U 1 i'7 ■ I'll' H k 'i 1 i 'M I '.•■A w \■■^ /{ 1" l( i i^Hilli WWi^ iM 302 TIIH XKKVOT'S SYSTEM. tlio cpitlu'liiun liniii, Taf. xiv, Kif,'. H.) <>, surfaee of epillielium ; Ixj, sul)ei)illielial eoiiUL'etivi) tissue : II, nerve fil)re. actual terminations, however, appear never to lie in the suiht- ficial layers of the epithelium, but the briinches, htiving ptissed out near the surfiice, turn backward to end free netir the junr die Eiidi^ijtinj; tier sonsiblon Ncrven in dei' llorii- haiit. .\rcli. f. imth. Anut., etc., IJorl.. Htl. xxxviii (1867), S. 343-386. (JitOUlMNO AND ('IIAI\I\(S 'nxJKTIIKIi OF NKI'IION'KS. 3(53 the cpitlidiiil liiytT of tlic conicii ( Kii;. "^14), shows in success- ful prcpiinitious ii largo nunil)er of tine librils. liul the iiiffro- /{ Fio. 212. — Ni'i'vi^ lilti'ils in tlu' ci*!!!!!'!!!!!!) of ii vcrticiil sccticin of tlic i'iil)l)it's lihidtltr. Method of (IoIkI. ( After (i. Hctzius, IJiol. riileisiieli.. StocUlioliii, 11. v., 15(1. iv, 1S1I2, T !'. xiv, Fifi. 1. 1 o, Mipi rticiiil layei' of epilliiliiil ctlls; /(;/. siiliepillii'liiil cimiicctive tissue; », nerve tilire passing from connective tissue into tlu' epitlieliuui. ill! €. t J I «i#iw MM? Fm. 213.— Tenninatioii in tlie form of trefoil end iilatelets on the ciliated cells of tlu' frog's palate. .SiKittal section; vital staining' witli methyW'ne lilue ; alum coeliineal used as a eounterstain. ( .Vfler .V. Hetlie, ,\reli. f. niikr. Anat., Honu, Hd. .\liv, 1S!)4, Taf. xii, Fig. t>. i t . t ■:p: Fk;. ^15. Tninsvcrsc sec- tion tlin)ii<;li the skin (if tile cur of a wliitc iniuisc three (lays old. (After A. van (ielmcli- ten, ('clliile, Licrre et I.ouvain. t. i.\, IHiCi, fasc. 2, pi. i, Fi};. 1. ) /». nerve tibrils; h, bifurcation; rif'r. Sc, I.ond,, n. s.. vol. xxvi. pp. Tjli-TO. + Seiiuize. F. K. I<'reie Nerveueiideu in der Kpiderniis der Knoehenfischo. Sitziiiii,'sb. d. k. Preuss. Akiid. d. Wissensch., phys.-inatli. ("1.(1802), No. viii, S. 87, 88. X vim Gchiichteii. A. I^es (enninaisons nerveusos intrn-epiderinir|ucs chez quel(|ues inamniiferos. Cellule, liierre et Jjouvain, t. ix (18!):i), fasc. 2, pp. ;i01-381. * Szymonowicz, \V. Heitriifxi' zur Kenntniss der Nervenendipungeii in ilauf,!j:el)ilden. Areli. f. inikr. Anat., Bonn, Hd. xlv (180.1). S. ()24-f)r)4. II IJethe, A. Die Xervenendigunfjen ini (iaunieii und in der '/auv^o des Frosc'hes. Arcli. f. mikr. Anat., Bonn, lid. xliv (1804), S. 185-20G. .41 t! 18? Hill ;{«!('. TIIK NKUVors SYSTKM. (ilM'il ; Hftlu' coiilil not, lidwcvcr, tiiid such structiircH in tis8iu>a lixcd l)V liis inctlKul. m ^ &r Fi(i. tJKl.— Nerves iiiiil nerve eiuliiins lYoiii the liiiinan ('(inieii. ( AfttT A. S. DoKiel, An.il. All/,., .leliii. liil. V, 1S!I0, S. ISS, Ki«. 5. ) .(, iiiediillMteil nerve tilire wliieli (liviiles iiiln two. (/miuI c, oI' wliicli one, i', e'lils in :i ('(iiii|miiiii, and in a liiiokh'l, A', hut the thread / h(d|is ti> Inriii the siiii]de skein ('; the hniindi 7' enters tile eoinidex skein, H \ tlie hnmeli /'" tiiially lireaks np into the threads/'" lind /"", ot" which the I'onner ends in a loop, /', whde tiie other j;oes into tlie skein C. The liraiudi ./'" is siirromnh-d for a ei'rtain distance hy i.iyelin ; nu- clei are, liowevr, iinniedialely adjacent to the tliveads f" and )'"". (i. bniiieh ofa niediillated tihre (not shown in the tij;iire) wiiich hrciks up into threads wliicli ;,'o over into the coinpouud skein, /( ; «, eenlial lihri' ; /(, peri- plieral part ot'axoiie: c, myelin. AnotluM' form of end platelet with wliieh liistolojrists have heeome familiar since Merkel's * descriptions is tliiit to be met * Merkol. Fr. Uobor die Eiidiijunfj dor seiisiblon Xervcn in dcr Ilnut. Naehr. v. d. k. Gpsollsch. der Wis.senseii. n, d, (ieorg-Ang.-rniv.. Oottiiigcn (1875). S. l'J;?-l'2S.— Tastzolleii iiiid Tastkorpen lien lie! den Ilaiislliiereii mid bciiii :\Ieii.selieii. Airh. f. iiiikr. Anal.. Umiii. lid. xi (If^T.")). S. (;;!(i-().V2.— Ueber die Endifjiiiifjen "tr sensiblen Ncrven in der Ihiut der W'irboltiere. 4to. Rostock (1880). •!«4'li (IHOinMNCl AN'I) CIIAININU TOCJKTIIKU Ol'' NKUUONKS. 3(57 with luljiKcnt to the well-known Taslvlhn of this author. Till' I'pitlu'liiil cell {'la fit ■.vile ol" Merkel) iidjiicelit to the tiKV tiU' mciiiseuH is ol" dilTerciit ulmpc, and posseHses entirely dif- ferent Ktuinin}; reactions from those of the other cells, go that wheji one is once fiiniiliiir with its ap|teariin(H' he can recv of^'nize it in sections which liavc! not heen stained especially <•» show the nervo endings. In tho skin, Merkcl's TantzcHi n are Kid. 217. — Verves and tierve eiidiiisrs in hnnmn (ornea. (After .\. S. DoKiel, Anat. .\nz.. Jena, lid. v. ISild, I'ifj. H. ) .1 ar.d /.'. two niediillated tilires, each id' wliicli divides l'iirl, as Szynionowicz; * has sli(»wn. I liavo staiiiod tlu'iii liy tlu' samo nu'tliod in tlio pijjf's snout, and also in liunian skin obtained from the surj^ncal operating room. W itli the aid of Ik'the's fixing method one can obtain beautiful pictures l)y counter-staining tlie sections with Czokor's alum cochineal. In a succ- isl'ul preparation the expansions of the ends of the nerve llbrils — the tactile menisci — are stained deep blue, the 'J'a.s/- zi'llcn kj2 Merkel dark red, and other epithelial cells pale pink. F!(i. ~MS. — Mcdullatcil iicrvc li^rc from the cimjiiiictiv:! of iiiiiii. ( After A. S. DoKicl. Arch. f. niikr. Aiiat.. Uoiiii, Hd. xliv, isiM-'li.'), 'I'iif. iii, Kifi. o. ' 'I'lw iiR'iliillatt'd til)rf ia) breaks up into single liraiielies ih) and smaller divisions still (<•). which form a idt'xus beneath the epitheliiiin. Merkel tliought at first that the Tdntzrllcii were actually gan- glion cells. Now we know them to be simply modified epithelial cells in contact with .special disklike expansions of the nerv(? fibrils. The stiuctnios have been aptly compared to an acorn, the ditrerentiated cell cGrres])onding to the nut, the meniscus to the cup in which thy nut ^its, and the nerve filiril to the stem of tilt: cup. Kallius looks upon Hethe's end i^latelets, de- scribed above, as transition forms between the simple free inter- ♦ Szyinonowicz, W. Reitriigo zur Kpiintniss dor Nerveiu'tnli{?unj;en in Hiiulfjehilden. Uebcr Han and Kntwiekelung dor \erveneii(li<;un,i;t'ii in (ler SciiniiuzL' lies Scliwoiues. Areii. f. inikr. Anal., Bonn. Hil. xlv (I^i>5), t^. 0:24-635. 1 GROUPING AND CllAININO TOOKTllER OF NHUIioNES. ;5«;«) colluliir iiorvc oiidings unil tlio eiuliug in inciiisci on Morkcrs Til.shrl /{')/. A coTiipn^lunisivc si'rii's of rosi'iircht's on I lie fio-cjillcd (iraii- dry's* corpuscUis, which arc fouud in tho duclv's bill (Fig. 2'22), ^^M^m Fio. 21!).— NtTVc cii(lin«s ill cpitlicliuni of froR's palate, i .Xf'tcr .\. Hctlic, .\rcli. r. iiiikr. .\iiat.. Uomi. 15(1. .\liv, 1S!U 'iC), Tiif. .\ii. KiK>. •„'.:?, and I. ) Vital staining with niclli.vlfiii' hiuc Fi.\ali,72 THE NEl{ VOL'S SYSTEM. von Frey * puts it, "• Every hair is a lever whose sliort arm is in the sl\iii, wiiile the long arm serves for the recieption of the i - A B Fm. 224.— Tactile tliscs from two (tninilry's corpuscles in ccpiiiieetiou with the axis cylinders (/n/)of the nerve fibres connected with them. Methylene- lillle stainini;. ( .Vl'ler .V. (le)perj,', Inlernal. Monatssclir. C. .\nat. n. I'liysiol., l.eip/., l'>d. X. ISiCJ, Taf. ix, l''i>;s ti and (>/;.) t die sees the axis cylinders jjo over into thi' tactile disc, where the stained tihrils or lin miles of lihrils of I he axis cylinder hreak up into delicate threads whi.').— Xervo endings about a larcre hair from tlio dosr. fAfter T?. nonnet, Alorpbol. .labrb.. Leip/.. ltd. iv. 1.S7S. Taf. x vii. Fij;. 1. ) rin>;, ,V /i' : I' S, circular sinus; N/', siiouKy l)ody ; r, circular ridye ; M. muscdeof the f(dliide ; /•', fat. ^ lilt' h a>! 1 1 ! ! 1 , 1 1 i 1 ■ 1 '^ t i li IN i ■ 1 8T4 THE NHItV'OUS SYSTKM. stimulus." The ciirlU'i' studies of liouuot,* M('rl\('l,t and Arustcin J showed tlu; intiiuute relation of rnedullated nerve fibres to the hairs, and indeed to a particular part of the huir (Fi^a. 22^1, 2'ii'>). dust below the spot where the sebaceous ^hnu\ opens into it the hair foUiele shows a furrow about it, beneath wlii(di is a jjrojec^ting rid<,'e. The nerves conneeted with the hair folli(de approach this ridge and penetrate the sheatii, los- ing on entran(!e their nuuluUated coverings. The further fate of the nerve rd)rils was for some time not clear, though lionnet by means of chloride of gold staining showed the existence of lutrizontal branches running al)out the hair. These branches gave (df asceiuling twigs which api)eared to lie upon the glassy mendtrane of the hair follicle imbedded in longitudinal folds in this structure. There seemed to be some doubt whether or not the fibn^s went through the glassy nu'inbraue ; many be- lieved that they did not perforate it but simply lay upon it. The method of (iolgi in the hands of van (Jeluuditen* and Ketzius II has shown the general characteristics of the endings about the hairs in the mouse, rat, and man very clearly ami sat- isfactorily (Fig. '2'i'i). In the mouse and rat ea(di hair receives one nerve fibre which has its origin not in the deep nerves of the skin, but as a branch of a neigldxu'ing fibre which is des- tined to innervate also a portion of the epidermis. This fact is of great interest inasmuch as it proves that either the hairs and these portions of the epidermis have to do with the origin of the same quality of sensations, or if they mediate different sense-modalities then the same neurone must be capable of transmitting from the periphery to the centres impulses con- * IJoiinet, H. Studien ueber die Innervation der IlaMrbiiige der Ilaus- tiiiero. Morphol. Jain-b., Leipz., lid. iv (1878). S. yj!)-:i!)8. f Morkt'l, l''r. 'i'astzc'llcii uiul '{'astki'lrpcrclu'ii l)oi di'ii Ilaustiereii uiid beiiii .Meiisclieii. .Vrcii. f. iiiikr. Aiiat., iJoiiii, I5d. xi (187(5). t Ariisti'iii, (". Die Nerven der beliaarteii Ilaiit. Sitzunysb. d. k. Akail. d. Wisseiiscli. Malii.-naturw. CI., Wieii, III. AhU, Oktober. 187(5. * \'an (Jeliuehleii, A. Les iierfs des polls. IJull. Aead. roy. de se. di' Bel-,'.. Unix., :5 s., t. xxv (18!):!), pp. •2;JO-'.2;i2.— bes nerfs des jioiis. Mem. do I'Aead. roy. de Helj;., Unix., t. xlix. 18!»:i. — Cdiitributioiis a IVtiide de I'iii- nervatioii des polls. Aiiat. Aiiz., Jena, lUl. vli (1892), S. 341-;M8. II Ketzius, (i. I'eljer die Xervoiieiidijjiiii^^eii an den llaai-eii. lilol. Unlersiieli., Stoeklinjin. ii. F.. I$d. iv(18!)2). S. 45-48.— I'eber die Kiidi^'iinj;s- weise der Nerven an den Ilaaren des ]\b'nselien. Hiol. I'litersiieli.. Stoek- holni, n. F., lid. vi, S. (51-02. lUh. <:: 1 'ill (IROrPINO AND niAININO TOOKTIFKR OP NEURONES. 375 cernod in the production of more tlian one sense-riuality. The nerve fibre liuving reached the hah- fulli(de, divides into two brunches whicli run horizontally about the hair almost at riglit angles to its course, one division running in front, the otlier behind the hair. Tliese may meet or they may run only part Hi. Fi(i. 227. — Nerves and lU'i'vc t'luliiifis in tlie skin and liair follicles. (After G. Ketzius, Hiol. rntersucli.. Stncklidlni. Hd. iv. isi);>, Taf. xv. Fiji. 4. ' list. stnitiiin riirneuni: (//i, stratum Kerininativmii MalpiKliii : c. nuist supcilicial nervc-tibre plexus in the cutis: », ciitancmis ncivc ; is, inner rout slieatli nf hair: iis. outer root sheath ; /(. the hair itsi'lf: tir. fjlandiihe seliacea-. Mi:' of the way around, thixa forming an incomplete ring. Snuill ascending twigs run up from these horizontal briinches parallel to the dii'ection of the Iniir to terminate, according to van Ge- 1 M| :| ^ 1 1' .•{Tiaiie : h. sIniiKht terminal lilires external to the jilassy inenihrane which inn uiit into s|Hiiin-sha|)cd nr liatcliet- shapcd endinus. Flo. 2211. — i.iinniliidiiial view of tooth of (ioliins. sliowiii^ nerve terminals. l.M'ter le.\Mse\teii(liii« lielweell I lie riiws (if liver eeils :/(, liliriU wliicii I'uiiii a iictwink dver (lie eell.^ ; c, r(>w.s (pf liver cells. That the teeth are sensitive to touch, and more especially to pain, is a matter of fieneral knowledfjje. It lias l>eeii disi)uted whether or not besides the nerve endings in the i)ulp there * Ostronmow. P. Die Xerveii der Siinishiinrp. iiiitgi'toilt v. I'rof. Ani- stein. Anat. Aiiz., Jena, IW. x (W9'}). S. 781-790. ^^i|il1l i\ Ay ' 'J ill i I ■" ■.. ; i I ; iM i •ii - t hi' 1^' :{78 TlIK NKIIVOUS SYSTKM. , won' jilso norv*' (iudnif^s in the Holid jjortioii of the tooth; while soinc havo bt'lii'Vt'(l tiiiit the iii'rvt' fibrils cud only unioii<,' tilt' liodics of tlio odoiilol)liists lit the pcriphory of the pulp, others think that they may actually pciu'tratc the dentine itself, inasmuch as it is known that if the j^utu he re- Fl(i. :,';51. I'criaciiiciiis plexus [n) nf nerve fibrils in tlie |i;ineii'iis. (After K. .Miillir. Anil. f. niilipte der Xerveniiistolni^ie. Hicl. rnti^rsucli., Stockluilin, 11. 1'.. 15d. iv (18!)'J), S. 05-(56. — Ueher die Xerveiieiidiguiijjeii in tlen Zilhneii bei Aiiipliibien. Hiol. I'litorsuch., Stockliolm. ii. I"\. lid. v, .S. 40-41. — Zur Kenntniss der Kiuli,i!:uiii.;s\veise der Nerven in den Ziihneii der Saiigetiere. Biol. Untersuuh., Stuekliulni, ii. F., Hd. vi, .S. 54. (}R()n>r\(! AM) ('IIAI\I\(} TOCiKTIIKU (>F NliritONKS. ;{7«> iiials, iiiid liiis siiccetMlod in stuiiiiiig tlie nerves (Ki;^. 2'V.i). lie finds that the nerve fibres of the pulp brunch niunifoldly and l'"l(i. 23'.J. — Ncrvi' rcllsMiid ncrvi' (iliri's in the villi iind aiiiniij; the Klaiicls of the iiilcsliiHim ttiiiic ol' (lie miiii(';i-|)i>;. (At'lci- S. iJiiiii('ni y CmjhI, tai;cii Iriiiii A. OpiHl's tcxt-l k. ) II, li, <\ il, pcfikaryiiiis nC (lillcrciil siiapi's aiiiidiH kI:iii(ImIii' intcstiiiiilcs ( I-iclifrkiiclini ; c. /, pcrikiiryniis situated in tlif villi intislinalcs; the plixiis I'driiicd liy their prdccsscs is sliowii. nro distributed between the odontoblasts endinjj close or near the inner surl'aee of the dentine. He was never able, however, to follow nei've fibrils into the dentintil tubules. Sul)sequently the subject has been submitted to especial research by Morfjen- stern,* who has obttiined very reniarktible results. lie describes different sorts of endinifs not oidy in the dentine itself ])ut also even in the enamel. These fuulings have been disputed by * Morjjcnsteni. M. Tehor das Vorltniumoii von Xcrvcii in den hartcii ZMliiistibsian/eii. Deutsche Monalselir. I'. Zalinli.. Loipz.. .lalii's. x (1892). Okto- ber, S. 4:i')-4:)T. — W'eileres iicIkm' ^'()l•k(>nun(■n von Xerveii in den liarton Zaliiisul)staii/,en mid iielier einc Metliodo sie aufzufitidcii iiiid zu konser- vipivn. Ibid., Jalii-g. xiii, S. 111-114. TIIK NKU'.OIS SYSTKM. Kl(t. !j:iH. Ncrvi' ciHliiiKs ill the siiliviiry kIiiihIs. (After . — Ncrvi' tel. ( At'liT (i. Scl:ivilin», iViiin Ivillllier's text-lMiok. ) (i|{(»nMN ClIAININ'd T'KiKTHHIl oK NKrilONKS. ;{,sl Urwc,'" who thinks (hat Morjicustcni liiul to th-iil \ulli jin-cipi- tiitrrt in ihiMlfUlimil tiihulcrtuinl on the iirncti^HHis of iho (xhnito- bliistrt. I'or thf prcHciit, then, we imist uwiiit piiticiitly tin; rcHiilts of riirthri- rfsciircli in this (lircctldii. Astolhc h('^imiiiij,'s of ci'iilripi'tjilly l"i;mi iicilii Scssionc ild l.T (iiMiimio, l.SHH. — Snpni 11 dislriliiii- iiHMito i> la tcriiiiiiazioiH' delle lilirc iutvcc iwi |iiilinoiii della rana U'Iii|m)- raria. liitcriiat. ^loiiatsclir. f. Aunt. u. I'liysi;57-',M!». I {{crklcy, I!..I. Studies in llic liiver. InlrinNJc Nerves. Johns Hopkins llosp. IJep., Hall. (1S!M). *• Knrolkow, P. Teller die Nervenendigunyon in der Leber. Anat. Anz., .lena. I?d. viii (IS!):]), S. 751-75;j. 4: I.- • lli i \ III ■■;i, m , iH'! Il M ■J i.f 'i ■tfl!iW^ ;582 THE NEKVOl'S SYSTEM. liver substfinco {Vig. 2.'50). The puncreas (Fig. 2'U) as well as tlie stomach and intestine (Fig. '^^3:^) have been studied by Erik Midler,* and liy Kamou y Cajal, and the salivary glands (Fig. 'iXi) and the thyreoid have also been investigated by several observers. The endings in tlie epididymis have been studied by Timofeew (Fig. ^;{+), tliose in the testicle by Sela- vuiios (Fig. •^;5o). Tlie sensory as well as the motor and secre- tory nerve endings in the mammary gland (Fig. ^^J'l) have ->;;■'- ' •r'-'-'-'i* 6 ; c Fid. 'i:X7. — Two I'orpnsclps coiitiniiiuj,' iicrv.' I'luliiiKs fnnii tin- external cen- iiective-lissue slieiitli ef llie (Icp^'s indslate. (After Tiiniit'eew. ISil"). rnnii Haulier's text-l)cMik. I it, thick iiiediillaled nerve tilire wliieli riiiis (iiil iiitu til' liaiid-sliaped axis cylinder; It, delicate inediillaled nerve lilire wliicli forms the t«'rniina! apparatus; iiietliyleiie-hlue stainiiif,'. lately been studied by Dinitrijewski.f Two corpuscles from the l>rostate are shown in Fig. "X'Xt. AVithout going into a detiiiled description of the findings in these various orgtins it may be stated that everyone has been surprised at their eiu)rmous ricli- ness in nerve fibrils. * J'iiller, E. Ziir Keiintniss der Aiishreitimg niul Eiuligurif^sweise der Magcn-, Diinii- and Pankreasnerven. Arcli. f iiiikr. Anat., Bonn, M<1. xl, S. 31)0-409. + Dmitrijcwski, P. Ueher die Nin'v?ii des Milclidrliscn. Diss, Kiismi, 1H{)4. abstracted hy Stiedii in Merkul-Homiet's Ergebn. der Anat., lid. v (lylir)), Wiesb., 1890. i f! CHAPTER XXXI. TJIR MKOl'LLATKI) PEHII'II KKAL AXONKS OF TIFK PKUIPTTKRAL CKNTUII'KTAL NKLKOXKS AXI) TIIICIU TKUMINAL Al'PAKA- Tl'S — {('(nitiHIIl'd). Sensory nerve begiimiiigs in niosohlastie tissues — ("oriiini and tela suheii- tanea — TuniciP nuieosa' and tein; subinueosa' — Meninf^cs — Tendons — Conneetive tissue of oriiaiis — \'()luntary, eardiac and sniootli muscle — Nerve terminals in [lathologieal growths. Sensory Nerve Beginnings in Mesoblastic Tissues. Wk next have to consider the disti-ibution of tlie peripheral extremities of tlie centripetal nerves in tlie various niesohlastic structures inclu(lin. i One" sees a iutvc tilu'e fiitfr iViiin liclow on each side and l)reaU up to tnrni an cud plexus, ."^zyumuo- wic/. thiuUs that thiscudiuK is icU'Utiial with the tcriiiiiKiismi hi'dn-ii'ormr nl' Kauvier. In tlie skin tit the junction of the corium with Uie epidermis itiinvier has described whtit he calls frnnitHiisons hi'di'rifoniirs. 'riiese have subse(|ueiitly been studied by tlie methvlene-blue method by Szymonowicz * in the snout of the pig ( Fig. :i'.\H). Op. cit. 383 !ii ! \ i iii 11 m mx, 8 Jiiiiii ■ 1 t! 'iii. i |||fl^H| ■I 1 j |H 1 > i ■ X^^B^^K^I 1 384 THE NERVOUS SYSTEM. They consist of axis cylindors which divide manifoldly and form irro|jjuhir dendritic end-])ranciiings and end-pU'xuscs, the fibres often showinj^ varicosities in their course. According to Szymonowicz, they are more deveh)ped in the parts of the skin in which Mcrkel's Tastzvllvn in the epich'rmis are absent or present only in small Tinmbers. They often lie im- mediately upon the basal membrane, following exactly the indentations and irregularities of the junction of the epidermis with the corium. Szynu)no- wiez could not make out, however, N that any branches ever passed into the epidernus to run among the epithe- lial cells. The endings lyiug upon the glassy membrane of the hair follicles also represent free nerve endings in the coniu'ctive tissue. Of the special eiid-organs occurring in the connective tissue of the skin several interesting forms have been described. First of all the tactile cor- puscle described long ago by Wagner and Meissner* is familiar to every one (Fig. 'i'-V,)). X section made through the skin of the pulp of the finger shows numbers of these in the papilhv of the corium. Sometimes the corpuscles are simple, but they may consist of several lobules with a com- mon base. One or more nerve fibres enter the lobule at or iu>ar its base; after taking a somewhat tortuous course each plunges into the corpuscle, loses its myelin sheath, and divides repeatedly with forjiiation of a definite end arborization inside the corpus- cle. Each termiiud branch runs out to end free, usually as a * \Vay:npr, |{.. iiml 0. Moissiior. T'ohor dns VorlifuuliMisoin liislicr unlic- knniitcr oif^ciitliiimliclicr 'J'iistkririicrclK'ii (Corpusfulu tiictus) in don (ii'fiilils- wJirzc'lKMi dcr nuMischliclien Ilaut nnd ueber die Endausl)rcitung sensitivpr XorviMi. Nadir, v. d. k. (iosi'llsch. d. Wissonsch. ii. d. Goorii-Aufj.-riiiv. Gutting.. lHr)'2, S. 17-32. Also IMoissncr. (i. Heitriige zur Anatoniie iind Phy.siologie dcr llaut. licipzig. 185:5. — /nr Lehre vom Tastsinn. Ztsehr. f. rat. iiiod.. licidi'll).. n. F.. I5d. iv {\KA), S. 2(!()-'JH().— Untcrsiicliungen uebur den Tustsiiui. Ibid., a K., Bd, vii (1«5!)), S. 02-118. Bl Ft(i. ;.'3!1.— Tactilo corpuscle cil' Mci? ,ncr IVnin a section tlinnifih the skin of the hu- man toe. Fixation with os- inica<'i'/. hi 1-vessel ; A", incdnllated nerve fibre. (After P. Schicirerdeck- er, (iewehelehre, Hrann- sclnvcij;, ISid, S. '.2^1. Fij;. 141.) . 240. — Section tliroufih tI)o skin ciftlio tod. In tlirpt> pHpillii' Mcissnrr's cin-- imsiUs with stained nerve lihri". are visiMe <(, stratum heiiini'i ; h, stratiin Ki'antiliisnni ; c, stnitiiin .Maliii«lii. (Alter .^ . S. I)ii«iel. InUrnat. -MonaLsseiir. f. Anat. u. Physiol., lA-iv/.., m ix. IHUa, Tal'. v, Fi«. 1.; Fio. 241. — M('is,sncr's corpuscle, a and a', axis cylinders of nerve fibres, which enter the cori)nscle antiate tlie toiM(j.'iii|ili.v of the "terniiniil nervous organs "( O.V ) (leserilied liy Kullini. i After A. KiiHini. Aieli. ilai. de liiol.. Turin, t. xxi. 1S!(4, pi. iii. Fin. V.i.' Cliloride-of-Kold preparation. At. arteriole; cV. Meissner's eorpuseles ; rl'. tninsverse sections of Pacinian eoriiuseles; . sudoriparous j,'lanils : 0.\. Kullini's endinjjs ; >y), papillary layer of the skin ; >')■, reticular layer of the skin : -.n. fat. show that the same nerve fihre mtiy be connected Avith more than one tactile corpuscle, and Dogiel stiites that he has seen fi])res cjiter the corpuscle, pass again out of it, and enter the epithelium to termiiuite there. End corpuscles (Figs. 24;{, 'H4) !-*•■•. ^a(IW*«W*~~ l-v 11 GROUPING AND CHAINING TOGETIIKR OF NEURON KS. 389 Fl(i. 24fi.— Rnffini's nerve ciKlinss (nr- (imifx iirnrii.r terniiiioiu). (Alter A. UuHini. Areli. it;il. de l>iiil.. Turin, t. xxi, ISiU. 1>1. i. Fifjs. 1 and 2.' Termi- nal nerv(> eylinilers t'i)riiie(l of various tilires eoniiii).' rmni the divisinn and siilidivision of a siufrle nerve tilire ; all. niveliu slieatli : ('. terminal inter- laeinKs (if tile axis eylinder : /-. eoii- nective-tissue slieatli. ,1)1 1 1 11 'li :;!' i: I 'H- ¥i 390 THE NKUVOUS SYSTKM. somowliiit similar to Mcissnor's rorpiisclos, but much simpler, have lu'en described in the eoujuiietivii of Imiiuin l)eings by Dogiel.* A special variety of terminal corpuscle has been described in the subcutaneous tissue of the human finger by RutTini. These l)odies, wliich are oval in shape and about as numerous as tile corpuscles of I'acini, lie at tlie junction of the corium and tela subcutanea, and often, according to Kutllini,f in the connective tissue septa which separate the nuisses of fat in the latter (Fig. 24o). These corpuscles, which he mimes orf/diies iicrrru.r frniiiiDii/.r, are ordinarily known in the bibliography as i? Fl(J. 347. — Tci'iiiiniil iicrvccorpuscli' of Kutliiii. Tlit' iicrvc (Dn'cs enter l).v one of tlie extremities of tlie eorpusele. It is easy to nmke out tliiit Henle's sheath Kcx't^ to form tlie eapsnle of tlie eorpusele. (After A. Hullini, Arch, ital. lie l)iol., Turin, t. .\.\i, l,si»4, pi. 1, Via. t) " Ruttini's endings." They receive their nerve fibres from the side (Fig. ^-tO), or more rarely from one end (Fig. 247). The nerve fibre, when once inside the strong connective-tissue sheath, divides into numerous branches which show varicosities * Dogiel, A. S. Die Xervcnemligungen ini LidraiHle nud in dor Con- junctiva palpbr. des Mensciien. Arch. f. inikr Anat., Bonn, T?d. xiiv (1894-'95), S. lu-a.! f RnHiiii, A. Di un nuovo organo nervoso terniinale e sulla presenza del irpusroli Golgi-Mazzoni ncl conncttivo .sottocutaneo doi polpastrell delle uita deir uonio. Mem. d. R. accad. d. Lincei, Anno cci.\xxvii (189.3). — Sur un nouvcl Organe nerveux terminal ot siir la presence des corpuscules Golgi- Mazzoni dans le conjonctiv sous-cutane de la pulpe des doigts de riiomme. Arch. ital. de biol., Turin, t. xxi (1894), pp. 249-265. ^' F"* nr OROUPING AND CHAINING TUGETUER OP NEL'KONES. 3<)1 in their course and end in small free end knobs. Huttini be- lieves that they form actual anastomoses before terminating. The Ruffini ending is seen in cross-section in Fig. 2-lH, and in ncc ^^■•■11 Fig. 248. — Tnuisvcrsc section nf Iviilliiii's tcriniiial (•(irpiisclc. I After A. Ulitliiii, Arch. ital. de biol., Turin, t. xxi, 18it4, pi. ii, Fij;. 12.) il ncc il t i 1 % m i Fig, 249. — OtilifHK^ seetion of a terminal norvo conuiscle of Hiiflini. (After A, Kuffini, Arch. ital. de hiol., Turin, t. xxi, 1804, Fig. 11.) i^' rr — I ■'i\ ^ ^^H ' 3'J2 THK NERVOUS SYSTEM. obli(|U(> section in Fij,'. •^4!). Ruflini's fmdinfjs liavo been con- firnaMJ by Sfainoiii * and by von Frcy. That a numbt'r of (jiul- FHi. '-50. — A nerve til>re is slmwii dividiiiK iiit" seven seeondiiry titires tii wliicli are iittiielied tive iiniinir.i iiirmix lirniiiinii.r of Kiifl'uii. (AI'tiTA. Kulllni, Ai-eli. itiil. de liidl., Turin, t. xxi, isiu, pi. ii, \'\>i. 10.) iuffs may be attached to the subdivisions of one nerve fibre is well shown in Fifj. 2f)(). These corpuscles of Ruttini while they resemble the corpuscles of (Jolgi and Mazzoni, are really dif- ferent from the latter. A somewhat simpler structure than Meissner's corpuscles is met with in the so-called end bulbs of Krause,f which occur in the skin and in fjrcater numbers in the conjunctiva. Kach corpuscle consists of a sheath made u]) of Hat connective-tissue cells continuous with the perineurium inside which is the so- called inner bulb, a finely granular mass which shows some- times a concentric lamellation. In the centre of the inner bulb is the axis cylinder, the myelin sheath having been lost at its entrance into the organ. The axone ri;ns out to end (piite free at the upper end of the bulb, usually terminating in a slight button-shaped thickening. These structures have been studied also by Szymonowicz with the methylene-blue method. ♦ Sfamcni, P. Recherches comparatives sur los orffancs nervcux terini- naux lie Kiillini. Anat. Anz.. Jena. R<1. ix (1804). S. 671-6T6. f Krauso. \V. Die terininalen Kcirperchcn der einfach sensiblen Nerven. Hanover (186(»), Svo. liir GROUFINO AND CIIAININO TOdKTIIKU OP NEURONES. 3«J3 IliH Hiulings uru well illustriitcd in Fi}r. •v'Al. The ciKl-hulhs in the conjuiictivji where Kniuse first discovered them have hoeii descrihed by Doj^iel (Fiff. 'i^'^). Not unlike these simple evlindrieal end-l)ull)H of Kriiuao, and diireriuy fruni them in reality mainly in the comijlexity of the eapsule, are the peculiar cor- ptiseles variously known as the corpuscles oi Vater, of Pacini, and of Ilerbst.* Tiie <,'eiu'ral apitcaniniHi of the Pacinian cor- puscle from tho cat's mesentery is well known (o every medical student, since it forms a stamlard K j; .*. 1. I ■| i Fl(i. 'jr)!. — Kiid liiillis slaiiuil liy tlii' iiU'tliylciic-Miic iiictlKid. (After W. S/.yniiiiiipwic/., Arch, f, iiiikr. Aiiat.. I5imii. M. xlv, ISO"), Tat'. x.\.\iii, Mys. I and ;{. I ((, .spirally twisted end Imlli ; t'le a.xis cylinder, the inner l>ull>, and the connective-tissue layers can lie seen : the small piece on the rii;lit-hand siile liehiw priilialily liehmtis tii a seciiiKl end liulli. h. terndnal <'iirpnscle com- posed of .sever,! 1 end hnlhs. ^dy--^,,si~'-^^ Vlu. i'ri. — Terminal <'or])nsc1e from the cdfif of the con.innctiva hnlhi. (AftiT A. S. Doffiei, .\rch. f. mikr. Anat., Honn, l?d. .xx.wii, ls!M. Taf. xxxiii. Viti. 3,) II. niednllated nerve (ilire, tiie axis cylinder of whicli Koes ovi-r into a deii.se end skein. object for study in every histological course. The corpuscle, large enough to be visible to the naked eye, has a translucent * Herbst. O. Die Paeiiiiseheii K()r|H'r iiml iliri' Hedeiitung. VA\i Beitnig zur Kenntuiss der Nervenpriinitivfasern, Gottingen, 1848, 8vo. ii <■:'! M -! '6\)-k TIIK NKUVOUS SYSTKM. uppciinmce. Tlic fil)r()UH nhciitli of tlif iicrvo is continuous with tlu' conni't'tivK-tissuc Hlioiith of tlio (•ori)UscU', tlu- latter con- siHtinj,' of from twi'lvo to tifti-en or niorti coucontrio huucllu'. Tho niyi'lin siiouth passi-s for Homo distance into the orpin, hut as soon as the nerve lihre lias reached tlie inner hull) the myelin sheath disappears and the axis cylinder runs naked in the centre of the inner hull). At the apex of the hull) the nerve flhre often divides into several processes, all of wliich run out to end free in tho granular suhstanoo of the hull). Khrlicirs nu^thod is very suitahle for the study of these structures, as Dogiel * and Kalliusf have shown, inasmuch as the nerve lihre stains of an intense hlue or purplish color, while the granular suhstance of the inner hulh stains only feehly (Fig. '^r^'i). UetziusJ has A s*^^5?^'a?»> H Flo. SiiS.— II(>rl)st's rorimsclcs. >[ctlivlin('-l>lii(' stainiiiR. (After A. S. DoRicl, Ai-ch. f. Aiiat. n. I'liysi..!., Liip/.. ls!»l, Aii;il. Al)lli.. Taf. \i. Via. H.l Tli(> axis ('.vliiidcr I'lilrrint; llif nl tenuinal tihre point where one of the hranehes of the terminal tilire dividi's into a lar^e nnniher of hranches which tii> to form nnnieroiis terminal hul^'inj; (After L. Kanvier. Ti-aite 1 « Inl! { techniiiiie d" histologic, Paris, isT,'), p. <);.':5, Hk- :5"!'. ) 31)() THE NEIiVOUS SYSTEM. M* Rufliiii * (Icscrilx's ji modified form of Vater's corpiisclo in dilTi'iTiit parts of the body, '.viiicli he desij^niates the 'Miolt^'i- Mazzoiii eoi-])us(de." It is in reality the same corpuscle do- scribed by (iol^'i ill tendons {ride infra). He finds that the nerve filires inside these bodies divide ofteiicr than in typical Pacinian corpuscles, alth()U Fio. 257. — ftptiital nerve corpuscles from the mucous meinbmne of the glsins I)eiiis of the nihl>it. MetliyU'iie-hlue stiliuin^. (After (1. Uetzius, Interuat.. Monatsschr. f Aunt. u. Physiol., Leipz., Bd. vii, 1890, Taf. xv. Fig. 15.) nil 1^ ■un AH 1 1 / Fi(i. 2.'JH. — Cross section of fienita! nerve corpuscle from the clitoris of the nihhit. Fixation witii Fleiuniinfi's Huid : hieniatoxyiin staining. ( After (}. Ketzius, luternat. Monats,schr. f Anat. u. Physiol., Leip/,., Htl. vii, ISiid. Taf xv, Fiji. Hi. ) Ui I ■^ iS^ti 400 TlIK NKHVOUS SYSTKM. A pcouliiir form of iiorvo otidin^ liitlicrto undcscriluMl has bci'ii found by Dogiol * in tlu' coniu'i-tivc tissue! of the coriu'ji. lie has made out in this situation peculiar free terminals in the form of definite end-plateh'ts. He describes nerve Itranehes which ru!i more or less parallel to the marfxin of the cornea, sometimes in radial directions toward the centre of tliis struc- ture. At their extremities are found Hat (piadrangular or Fio. 250. — frpiiitiil iicrv<' corpiiscli's frmn liiiinaii tiliiiis penis. UKUUPING AND CHAINING TOGETIJEIi OF NEUIlUNES. 403 In ■ ■■ ) ■1 I I' ' M ':^m !.!!■»■ mi I! 40i TIIH NKitVOL'S SYSTEM. 1 (illOlTPING AND CIIAININC} TOCKTIIER OF NKriloNKS. 4o5 The sensory nerve endinj^s in tendons since they were de- scribed by (iolgi* in 1HT8 have been the object of many researches. Accord in}^ to (>ol}^i, tlicy form true terminal |»Ia(iiics, from two to thirty of these phi(|ues makin<^ up a sinj^le corpuscle (Fij^. v the ihtvc flhri's. He dciiu's dctiiiito ('iicaprtiiliition with cou- noctive tiHsuc, such us (lolgi descrihod, and furtlicr hiys strcsH on tho rc'liitioii of tlie fudinj^s to tlie tendons projuT, iiKU'ju'ndont Fkj. 2ti7. — Tciidinotis expansion of on(> of the motor luiisclcs of the eye of an ox. (After (i. V. Ciaccio, Aicli. ital. dc l.iol.. t. xiv, IHitl. pi. iv. Fin. 27. i Two musciilo-tciKliiioiis organs of (iol^'i miiti'd with one aimtlicr ami (•oiiii)rcss('il toward tlic lower cxtrt'iiiify liy a l)and of coiniective ti.-isue. Eaeli coriiiLselc of (iolf{i lias its own ultimate nerve phKiue. These two i)la(iUes show lioth the hushlike anil rinjjlike endings. ii'ii i 1»« r If !! f I t h. i ii M^ 4t(» TIIK NERVors SYSTKM. of till' muscles,;! vifw aufiiiu in coutriKlictioti to tliat of (iol«,M. The endings iilwiiys lie inside tlie tendons, a})piirently never on Fui. ^(is. - A, sciisiny nerve ending iVom exiicMnliuiii of upper IimII' nf lel'i alriiiin of I lie lieiirt dI' tlie Kray rat. U ami (', sensory lu'rve eii(liiij;s IVoiii the eiido- eanliiiiii ol' tlie ilo^'. (After A. Siiiiriiow, Aiiat. An/,., Jena, Hd. x, l.S<)r), S. Tir), Fi^'s. ;!. 4. r>. ) their sheaths, Ciiiccio calls them plaqto's trxdinnisrs arrr Irr- wiitaimn hnissonnensr t/rs tirrfs a s/iinr/s on u (iiiiirdn.r. As Jlliil! !>'*•'{ JV m (JUOUPIXG AND CUAINING TOCJIOTIIER OF NEUUOXHS. 411 wo liiive siiid, these ondiiif^s of (iolf^i, riaccio, and Mazzoiii aro probably closely allied to raciiiian corpuscles. As to the eiidiuf^s of nerves inside the interstitial connective tissue of organs we have data concerning the heart, lungs, and certain ])arts of the eye. The sensory nerve endings in the endocardium of the auricles and ventricles, as well as the auriculo-ventricular valves and the chorda' tejidinea' of ani])hib- ians and mannnals, have l)een studied by Sniirnow,* who has also attempted to nnvke out the alterations in the endings after seetioji of the nerves to which they correspond (Fig. v<>S). The nerve endings in the lung have been exannned by Herkley, Fl(i. 2()!). — Nerve emliutts in tlie liiUK of the IVoi,' ; liir^'e skein with iiiteiiuK niednlliited nerve lihre (// 1 and t\vi( tli reads havilij; the skein n. (After. \. Sniirnciw, Anal. An/., .lena. ltd. iii. l.sss, S. :i,-.it, Imk- ~. ) ("nccati,+ and Smirnow J (Kig. •W.)). The endings here in the connective tissue are not unlike those found in that of the heiirt. Melkich* has studied the free endings of sensory nerves in the connet^tive tissue in the iris of birds by KhrliclTs method and tlnds two viirieties of nerve endings in this region : On the posterior surface of the iris a ple.xus of very tine nerve fibres which, iifter manifold division and interlacing, end free, never forming atiastomoses. The other variety, situated near the * Smirnow, A. Uebpr die sensiblon Nerveni'iuliKun^t'n iin Ilcrzcn boi Aniphibipii mid Siinj,'i>tii'rcn. Anal. Anz.. Jona. Kd. x (IHflr)). S. 7:«-740. f ('ii('('ali,(r. Ihtonio al inodo onde i nervi si distrilmiscono etprniinani> ni'i |)ohn(iMi e iiei iiuiseoli addoininaii liei Triton (.'vistatus. bilcrnat. Mo- iialsclir. f. Anat. ti. I'liy.siol., Leipz.. Hd. vi (1889). S. 2:57-24!). Al^io IJuU. <1. sc. ined. di |{oloe:iia. fl. s., vol. xxiii (ISHO). \>p. :iO-l-:i(t7. \ .Smirnow, \. Vohw Nervenendkniiiiel in der Frosehliin^^c. Anat. Anz., Jena, Bd. iii (188H). S. 2rj8-201. * Afelkich. r Keiintniss des Ciliarkrirpers nixl dnr Iris bei Vogeln, initgelheilt von Prof. Arnstein. Anat. Anz., .lona, 15d. x (18'jr)), S 28-!i5. K' ,i;.hi 1, l:il!i P 'IH : :-i , « ;u ;; 'w"i! \: '^ li 412 TIIK NKRVOUS SYSTEM. muscle fibres of the iris, arises from the division of modullated nerve fibres which form free nerve endings after repeated den- dritic subdivisions (Fig. 270). He does not think that thev are motor fibres, but believes that they represent the sensory element in accommodation, the first variety, according to his B FUi. 270. Sensory nerve IfndiiiKS in tlic eiliiiry Imdy (if liirds. (Al'ter Melkieli, Anat. An/,., .lena. Hd. x. IS!),"), S. :{(», Ki<;s. U and :i. > A. sensory end arl)(iri/.a- tion I'roni tlie ciliary liody near the elastic riiiK; a, niedullate{.:>,) The lifliire sliDWsa didicate nerve stem wliieli breaks up inln sinjile nerve til)res, wliieli in turn run out to l'>»(- 1.12.— ncilrac ziir Keiinliiiss der seiisihlen Kndorirane. Anal. Anz.. .lena, Hd. ill (ISSS). S. ',>SH-2n(i.— relief die Fdrtschritle in dor Krkenntiiiss der Muskelsj iiideln. Anat. Anz.. .Tona. Bd. viii (lS!l-,>-ft:n. .S. 44it-4r)8.— Ikiner- kniifjen zu llerni Dr. .\ii!iel(i Hnniiii's Anfsatz: CniisidtM-azioiii eriticlie stii reottnti stndi ch'li' a|i|iMnit(> iiervdso iiei fiisi uui.sL-olari. .\iiiit. Aiiz., Jenu, Bd. ix (18!)3-'n4), S. r)5;{-503. P: !•; Kf Mm I 41 I ■ 1 1 J !' : 11 i. li 414 TIIK NKUYOUS SYSTKM. l>\ 'tl^y ~'i7./:si *d..J S M ^'* '■!•>- ^^^^ MiPi;^^: vessels, nerves, iiiid connective tissue. The whole mass of structures iuclosed in a coinnion sheath is considerahly wide r /, in the nii(klle than at tlie end. Lymph intei'spaces exist throu<;h- oiit the spindle, while through the centre of it runs a lymj)!! space of consideralde size. The slieath cor- responds in character to the peri- neurium of a peripheral nerve. At the ends of the spindle it is thin, but it increases in thickness to- ward the w'dened parts, 'i'he num- ber of striped muscle fibres present in a single apindle varies in its dif- ferent i)arts They are usually fewer at the ends, where the fibres are also finer, more numerous in the middle of the spindle, where the individual fibres arc also thicker. The fibres are l)eautifully striated, as one can easily make out in longi- tu. 211-258. * Kerschiier, L. Op. rif.. Anat. Anz.. .Tcna. 188S. S. 2!lo. !| Trinchese, S. ("ontriliuzione alia conoscenza dei fusi muscolari. Mem. r. Acca.l. (1. sc, d. 1st. di Bologna, 4. s., vol. x. 188!l [18!l()]. pp. 715-725. Also Transl. : ("ontril)iition a la connaissance des fuseaux niusculaires. Arch. ilal. de iii.il.. Turin (18i)()-'))l), t. xiv, i)p. 221-230. i\ }■ I, ) I r '-...1 Ill •ill : '' ' f'f >)|i \ :'i' 1 i 1 41(1 THK NKHVOUS SYSTP]M. tration of tlioso structtircs (Fi. \m. Fi^. 1.) .Sspinils; .1, riiifis ; /•', (Icudritic liiaiichiiiss. (Iiloridi'-ol-gold prt'para- tioii. ITnber, of Ann Arbor, has recently studied these structures with the methylcne-l)lne method, and has succeeded in obtain- ing exquisite jiictures of the nerve endings even to their ulti- * Rndini, A. Sulla tfriuiiia/.iono iicrvdsa iici fusi nuiseolari e siil loro sij;iiificato fisi(il(if,Mc(i. Xota pivvciiliva. Atti d. r. Accad. d. Liiicci. ("I. di sc. fis., mat. c iiat.. Hoiiia. ~. s., vul. i, 1892. — Siir la teriiiiiiutiori iktvimix dans Ips faisceaiix imiseulairesot siir Iciir sijjiiification physiolosiqiio. Aivli. ital. do liiiil,. Turin, t. xviii (1S!)2). pp. 1()(J-114. — ('(insidi'i'azioni critidio ."^ui receiUi stiidi deU' apparato ncrvciso iici fusi nuiseolari. Aiiat. An/., .loiia, Bd, ix (lH!W-'!>4). .S. H0-H8. — Sulla fina anatomia dei fusi neuro-museolari del tratto (' sul loro sigiiirK'ttto fisiologieo. Monitore zool. ital., Fircnze, vol. vii (18%), pp. 49-53. (HioriMXli AND (ilAIN'IN'd T()(JETIIKH OF NKrUOXES. 417 mate tcrTiiiiiatiiiii (Fi;:. '.'i.")). 'riiaiiks to liis cdurlt'sv, 1 liuve had tlu' opportunity of I'xaniiiiini: liis spt'i-iiiu'iis, and have -Tt^ I'lii. ;.'7l. — A stripril iim^clc liln'c in ;i Iiiiiiimii iiiiim Ic spiiiillf willi lirniiinii-iiiiis 'i llriirx. (Al'iii- A. IJiilliiii. Aicli. itiii. i\i- liinl.. 'riirin. i. wiii. l^lKi. p. Ill, V\ii. ,'.1 /.', Iiriiiiiiiil ciiiiirgciiuiits nl' the axis cyiiiMUr. ( lil(iri(l(-cit-<;iil(l pn iKiraliiiii. hecii iiiiicli siirj)ris('(l at the coiiiplcxity of the oiuliii'i'.s. His rt'siilts, to<,n'tlu'r witli i)lati's and a vt-rv coniplete bihlioirrapliy, have l)ecn enihodiod in a n-ct'iit pajxT hy himself and Mrs. Dc Witt.* Till" method of Silder t is also of great service in deiii- onstratiiiiT the niUfiele spindles. To .succeed with the method some care has to be taken in teasiiiir out the preparation. 1 have had the i^ood fortune to see soiiu' of Sihler's preparations, ami can speak in hiiih terms of his method. The contrast 1)e- tween the larijfe calihre of the seiisorv tiltres uoinir to tliese struc- ■ '" n ',; t-.: »'i ii! \ * Iluljor. G. ('.. and Lydm M. A. De Witt. A Contribution on tlic Motor Ni'i'vo FiiidinfTsand on tlu' Nerve Hndings in the Muscle S|iindk'.s. .1. Coniip. Neurol., (iranville, vol. vii (ISIIS), |i|,. lOW-',':!!). f Silder. ('. Ueber eine li'iciiteund siidiere Metliodedii' Nervenenditrunj; an MuskeU'aseMi und (ietassen naeli/uweisen. Areli. t. Aniit. u. I'liysioL. i'hvsiol. Alitii.. Lei|iz. (IS!).')). S. 20'2. — I'l'ber Muskel.-pimlein und intra- niuskuliii'e Nervenendis;nni::en bei Seldansjen und Fniselien. .Areli. f. niikr. Ainit.. Bonn. Md. xlvi (ISfl.j). S. 70!)-T'i:!. — .\ description of a simple and re- liable nietlu.d to trace the nerves in the muscle. Clevclaml M. Gaz., vol. x (b'^m-!).-)). pp. 'rM--2f.4. Also. Am. Month. Micr. .1.. Wash., vol. xvi (1S!I.-,). Pl>. IT'2-IS'^.— The sensory end-orjrans of voluntary nuiscle. Cleveland M. (biz., vol. \i (bS!».-,--ii(i). pp. oO.VOOO. 28 n il III >i iiii 'I ti ■ns THE NERVOUS SYSTEM. tiii'cs and tlio imu'li sniiillor ciilihiv <»f tlii' ordiiuvry motor nerve tihri's of iiuisclo was vury .strikiii<;. F'Ki. »75. — ^tiisclt' s|iiii(ll(' friiiii intrinsic pliintar niiisrics nf a do^. (After (i. ('. Ilnlicr and Lydia !)<• Witt, .1. ( '.mip. Ni iircil., (ininvillc, vol. vii, 1W»S, pi. .\\ ii, I'itl. IW. I Sy. II., syiniiallutic vasipniotor li)prc. The wliole inake-up of tlic inusi'le s])iii(llo or ncuro-innsciilar biiiHlU' imprt'ssi'S one as a structure esjjecitilly adapted its a sense organ to give information coneerning vtirious states of tension in the muscle. Contraction of the muscles in which they are situated must necessarily lead to alterations in the pressure of the lymph inside them, and I am inclined to tigree with those observers who assign to tliem tin important function in con- nection with muscular sense. The subject is, hoAvever, still obscure, and the last word concerning them has by no means yet been said. Renewed attention is being jKiid to them just now by the neuro-pathologists. I need only refer to the care- ful studies of liatten * iind (Iri'inbaum.t The nerve endings in the heart muscle have been studied by Herkley, J Dogiel and Tumarzew,* lleymans and I)emoor,|| * Button. F. E. Tlie Muscle Spindle nnder PatliDlogical Conditions. ISiaiii, Lend., vol. xx (IHiC), i)]). 1^8-17!). f (iriinbuiiin, .V. S. Note on Muscle Spindles in Pseii(lu-IIypertroi)hie I'aialysis. Bi-aiii, Loiid., vol. xx (1S!)T). pp. ;!(;r)-;j67. I Berkley, H. .1. On Complex Nerve Terminations and Ganglion Cells in the Mnsenlar Tissue of the Heart Ventricle. Aiiat. Aiiz.. Jena. Bd. ix (18!t;5-"!»-l), S. 33-42. '* Dogiel, J., u. Tnmarzew. Contribution to the Comparative Anatomy and Physiology of the Heart. (Russian) Medyeyna, Kasan (1893). Nos. 4(! and 47. Abstract in Merkel-Bonnefs Ergebnisse der Anat.. Bd. iv (18!)4). S. 2!t!); also Dogiel. A. S. Die sensiblen Nerveneiidigiingeti im llerzen utid in den Blutgefiissen der Saiigethiere. Arch. f. inikr. Anat., Bonn. Bd. lii (1898), S. 44-70. II Heymans, J. P., et L. Demoor. Etude de I'innervation dn ca-ur des 0ItOUI'IX(} AND CIIAINlNd TOliKTIIER OF XEUllOXKS. 41() Jac(|Uos,* and Iliilicr and Dc \\\U. Wlu'tlicr or not the com- 1)U'X felt work (tf til)ri'S whifh tlu'si' invi'.sti<,'ators find tlirouf^li- out the ori,'iiii have to do witli the mediation of centripetal im- I)ul8e8 or whether they are concerned wholly with the currying of motor impulses to the heart nuiscle fibres has not yet been determined. The fil)res in Fii visihlc fur MiiiH' ciistinicc. Mi'tliyiiiu -liliif iirciianilinii. Aflir A. Ai'iikIi in. frciiii lltiillirr's trxl-lMHik. I iiiaiiv to !)(' associated with spasinout whotluM- the pain in tlu'sc cases is tiic ivsnlt of stimnlation of Fiii •J7t-i — [,nn^;iniiliii il x'ctioii uf iiivulinitiiiy iiuiscic slidwinj; iicrvc I'lidiiiiis I AHiiMi. <" lliilii TMiiil l.yiliii Dr Wilt. .1. (nu\\>. Nciiml.. ( ininvill.'. vnl. vii, ISits, pi. xiv. I'ijis. ;.".' :iii(l ~':i. ) K.iixis < ylimlir t(iii\iii;iliiit; : /). tin- Icniiina- tiiiii itx'lf; II. imcltus 111' till' siniiotli miisi-lc ci'll. si'iisory niTvo iilu't's l)c',i:-innini>- in tiu* mnsclr itself or in the con- ut'ctivo-t issue structuros is not known. In the trachea intcr- •"■ L- fM{OUIMX(} ANT) CirAIMNfi 'nuJiyniKK OF NKFRONKS. 4.JI muscular nci'vc-ciidin^rs have Itt'cii (lenioustratcil hy Arnstcin (Fig. 5^77). 'I'lic iii'i'Vf ('ii(lings(k'scril)t'(l in connection witli the smooth musch' of tlic iris and ciliary __ holly ari' (louhtlcss concerned in the meciianism of pupiUary contraction and of accommodation reaction. In Fi^^. 'ijS the motor cndinjjs on the smooth muscle-cells of the intestine are illus- trated. Tlie iliulings of Hetzius on tlie vasa afferentia in the glomeruli of the kidney are shown in Fig. 27^. The nerve endings on the lymph vessels have recently hceii descrihed hy Dugiel.* Recently nerve endings have heen found ill certain pathological new growths. Thus Reisner f has found nerves in condylomata, and \'ollmerJ has also studied nerve eii lings in these growths. Young,** in his study of nerves in tumors,has successfully demonstrated nerve fibres, both medullated and iion- medullated, in a considerable number of these growths. He concludes that, in sarcomata at least, nerves are just as much an integral part of the tumor as are the sarcomatous blood-vessels. The nerves were not followed, however, to their ultimate terminations, and it must for tlu' j)rcsciit remain (loul)tful whether they represent purely vaso-motor tilameiits or whether among them dctinite sensory fibres also exist. Fid. -'"(•. — Nerve ending nii the Viis itll'ereiis in the cin- tex iif the kidney. ( After (i. Ketzins, Mini. I'nter- such.. Sinckhcplni. I in, ecir- pnsenhi icnis ( MulpiKlii) ; Id, vii.s iiU'erens ; 11, nerve. V ! * Ddu'iel. A. S. Die Xerveii ilei' Lyniphgufiisse. Arch. f. iiiikr. .\ii!it., IJciiii. I'.d. xlix (mil). S. Titl-Titr. + IieisiuT. A. Uebcr das Vorkoiniiieii vdn Nerveii in spitzcn Cciidyluineii. Arch. f. DeriiKit. ti. Syidi.. Wieii 11. Leipz.. lid. xxvii (1SI14). S. 3Sr)-:!!»(i. I X'ollini't', K. Nerveii uiid Nerveiieiidi;;iiii,i;en in spitzeii Condyloinen. .\r( h. f. Deiii'iit. 11. .Syph.. Wieii u. beipz., Bd. xxx (1895), .S. 3G3-;JH(». » Op. fit. Cf. Ciiiip. IV, p. :ST. I' mm k J. CIIAPTKn XXXII. CKN'TUAI. AXOXKS Ol' I'KIU I'll KKAL CKNTHIPKTAL VIU'ROVKS. l''il)rp.s of (lorsiil rcinls — Origin, (•oursc, hraiicliiiij,'. ami li'i'miiiatidii — liUtcral ami iiit'dial l)iiii(liL' of (|i>r>>al root — Kiitry zoiit' — Methods of stmlyiiij; inlraiiit'diillarv fdiitiiuialioiis of dorsal root llbrcs — Myfliiiizatiiui of lil)ri's — Stiidit!!! of Flcclisig, von Brclilerew, Kiirn.siii, and Trcpinsixi — Vt-ntral, middle, and dorsal root zones — Fleelisijj's oval centn — Heia- tioiisof inyclinizatioii snli-systenis to function — 'rrpi>inski"s four ftrtal snl)-sy.steins — Stuilies of tabes. CcufrfiJ A.rnui's of Pcn'/ifirrirl ('rutrijK'ftil Xcuronrx. — TTavin? considered tlie inedullated ])eriplieriil sensory nerve fil)res (distnl l)roeesses of the s|)inid »fan;,dioni(' cells) it is next in order to consider the proximal processes of those cells, those which enter the central nervous system. The central prolon<,'ations of the spinal gan.ulion cells (which tojrether make uj) in mammals almost the entire mass of flhres in the dorsal roots of tiie sjjinal nerves) apjjroach the s])inal cord and plunge int(» it ut the dor- sal lateral sulcus where the neurilemma of the individual fibres is lost. The fibres on entering the cord divide by Y-shaped divisioTi into an ascending and descending branch. Of these tlie fornu'r runs a shorter or longer distance before terminating in the gray matter of the cord or in the case of some fibres in the medulla oblongata or cerebellum ; the descending limb ter- minates in the gray nuitter of the cord after running downward for a very short distance. On their way these axones before and after division give off numerous collaterals which also run into the gray matter to end free among the cells and dendrites of cells situated there. In this way the mechanism is su])plied ])y means of which the impulses arriving by way of the periph- eral sensory neuroiu'S can be transferred to motor lu'urones in the cord or to centripetal neurones of a higher order which in turn conduct impulses to higher regions of the nervous system. The regions of termiiuition of the fibres are, it will be seen, of 422 s dorsalis. Arch. f. Psvc'hial. \i. XiTveiikr.. IUtI.. liil. xvii (1S8U), S. 377-4:38. V : f! m ¥ TV, I f']i 424 THE NERVOUS SYSTEM. division, coming into ivlation with other neurones only by con- tact or concrescence. A knowledge of the intramedullary course of these medul- lated axonesof the dorsal root fibres has been gained, aside from the simple topographical studies of serial sections, in the main through (1) the application of enibryological methods; {'-i) the study of secondary degenerations, {a) experimentally produced, antl (b) the result of disease in human beings ; and (3) the chrome-silver method of (iolgi. His's researches showed that the dorsal fasciculi of the spinal cord are embryologically the result of ingrowth of the central processes of spinal ganglion cells. A comparison of the number of fibres in the dorsal fasciculi with the total number of those of the dorsal roots prevented many from believing, however, that the dorsal fasciculi were made up in the main of dorsal root fibres. At this time the Y-sha])ed divisio!! of the dorsal root fibres inside the spinal cord had not been discovered. The myelinization of the various ]iortions of the dorsal fas- ciculi has been carefully studied by Flechsig,* von Hechterew,f and Karusin.J Flechsig's studies early convinced him that the fibres of the dorsal roots and of the dorsal funiculi do not become nu'dul- lated all at oiux\ On the contrary, definite groups ri'ccive their myelin at very ditferent periods. A study of human fcetuses at different periods of development has established the sequence of medullation in the dilTereiit l)Miulles, and Flechsig's description of the dorsal funiculi is based u])on the results of this developmental analysis, and largely upon jjri'parations made by Trt'ijinski in his laboratory. Each dorsal funiculus, exclusive of (JoU's bundle (fasciculus gracilis), can, according to Flechsig, be divided into the following areas : (1) The ventral root zone {rorilrrr \\'iir:c/:iiHr). * Flt'clisijr. P. Die Lpituiiffsbnhnen iin Gcliirn und RUekoninark. I^i'lpzij: (ISTfi). and especially in his article 1st die Tabes dorsalis eino " Systein- Krkraiikmii,'." NVirnl. (VnlniHil.. Leipz., IVl. ix (ISilO), S. :!:!: 7-2. t Vi.ri I5r !litere\v. W. Die I,i'itiiiii,'sl)MliiieM iiii (ieliirii und Iviiekenniark. I.eip7.iff(lH!t4). t Kanisin, P. Das Fasepsystem des Kiiekeiimarks. enlwickidiiiiirs'je- seliiclitlieh untersiielit. Moskau (1S94). Abstract l>y Stieda in Merkel- lioiiuet's Kri^eliiiisse der Anatoiiiie u. Entwiek., Hd. v (IHSi.")). S. ft."). OKUUI'LVJ AND ('1IAIXIX(J TOGETIIHll OF NKUUONKS. 405 --, ijpy ; ill h 1 f ' if 1 • : li i {'I) The inifldk' root zono (i/iiftlrre Wurwhitiiu). (0) Tlif (lort^iil root zonu {Itinlvrc WurzvIzuHf). (4) The meditui zone {ineiUune Zone dcr Ifiiifi'rsfra>/f/r). Tlie iiiediau zones of the two sides nmke u}) in the lum- har region what is often spoken of as tlie oralrs < 'nit ruin of Flechsig. The middle root zone develops in two parts (first and second systems of the middle root zone), as does also the dorsal root zone (medial and lateral portions of the dorsal root zone). Tlie position of these various zones is clearly shown in the accompanying diagrams (Fig. :2S()). The sequence of nicd- ullation is as follows : (1) The ventral root zone (Fig. 2S0, V.r.z.). (•.>) The first system of the middle root zone {M.r.z.) and the median zone. (o) (iolFs fasciciili, second system of middle root zone aiid the medial portion of the dorsal root zone {/Kr.z.). (4) Lasi. of all toward the end of fo'tal life the lateral por- tion of the dorsal root zone (Lissauer's marginal zone) (Fig. :.'S(), /'.A.). Of these the only bundle to increase steadily in cross section as one passes up the cord is (ioll's fasciculus. All other regions show in the thoracic cord, especially in its middle parts, a consid- erahlv less area in ci'oss section than thev do in the enlargements. As to the origin and termination of the nerve fibres con- tained in the dilferent fu'tal zones, Flechsig, when he wrote in IS'.iO, believed that the ventral root zone (V.r.z.) received very many, probal)ly all, of its fibres direct from the dorsal roots of the spinal nerves; they went, he thought, into the dorsal horn after a longer or shorter course. In front of the dorsal horn they vanished, although he could not make out their exact ter- mination, lie felt sure that they have nothing to do with tiie luu'leus dorsalis. The iibres of the first system of the middle root zone he ln'iicved come entirely from the dorsal roots and end after a short course l)y turning into the nucleus dorsalis (Clark ii). As to the origin and termination of the fibres in tlie median zone he could make no statement. Coiu'crning the fibres of (iolFs fasciculus, Fli'chsig could given irect proof from the study of tlie fu'tus that they have their :i in the dorsal roots, lie could first certainly demonstrate ihem as compact bundles of fibres in the rcLrioii of tlii' tenth thoracic nerve. Further down :& '• 4''^ ii.-; 'J \! t» . inifi : A D.r.T .. r9 (Am Fq. Rr.z. Fes.l , F. CSV Middle of iiitimip.sc('iitiu('crvi<'iilis : A. iiicnilicniiciit of ilnrsiil fimiciili iis rcvoalccl by study of luyi'liniziitioii ; B, lesion in a case of incipient talies. 1 ^-7 Mr.z D.,,z. D. ! r^ i 1]^. Fes. I. Fcs.l '•Fes.l. "Vr.i E. Pars tlioracalis : ('.section tliriiii};li niid-tlioracic refrion ilhistratinK inyelini/a tion nienibernient ; I), section tlivoUKii iiiiiier thoracic region siiowiu^' lesion in a case of incipient tahes. D.r.z'. FL.. Frs.L.- FL. f^')hM.n-t. V— Urz Intumesceiitia liimhalis; E, menilierment as revealed l)y study of inyelini/;ition ; F. li'sion in a ease of incipient ta'ies. Fl(i. ^»SO. — ri<;nres illustratin;; the dorsal fnnieuli in tlie cervical, thoracic, and liiiidiar regions of the spinal cord. Those on the left side illnstrate the eni- hryolo«ical nieiiilierineut, those i>n the rij;ht side the lesions iu cases of incipient tahes. ( .U'ter P. Plechsii;, Nelirol. Centralhl., l.eip/.., ]{d. i.\, 1S!H(, S. "J, Kifrs. 1. :,'. ;i. 4. 5. aii./•.;..) all come, according to Flechsig, from the dorsal roots. They leave the dorsal funiculi by three paths : { filn'fs of (idll's fascit'uliis have tlu'ir orij,'iii alsi) in tlie dorsal /oiu'. and iicrhaps evoii more widely. They arc indif numerous in tlie medial portion of the niiddlc root zone than in the laU ral portion. Flechsijj helieves. however, that the fibres of (ioU's faseicnln-! really represent intramedullary continuations of dorsal root filires, and urges against von Rechterew's ol)jeetion that the dorsal roots are all luedullated before GoH's fasciculus, that his own ohsei'vations sliow that when the filircs of (ioli's fasciculus receive their myelin sheaths there are still uuiuy lilires in the dorsal mots which are non-meduilated. f It will l)e noticed that this description liehnigs to the period preceding that ii' wiiicli collaterals were dislingui>hed from terminals. n it if % % k f ;i I ii in a 1 [ ^ % iji il lit « ') 'If fi t. 4-2^ TIIH NERVOUS SYSTEM. (•iiil)r\()l()n H' S3 F'n;. 2sl.— I"|)])or half ol" Imiiliar I'lihirKciiicnt (if":i fn'tiis ;5.1 cm. Idiit; ; ciprri'spdiiil.-. tn I'is;. '^so. K. /'.< liit( nil pyraniiilal trait : r, vciitial lonts iiicdullatiil ; h. ildisil I'lMitsiiartly iiii'diilhittil : ill', vciitial rout zuiu' nt' ilinsil funiculi; n IV, dcirsal rciot /uuc i lateral |i■••■. dorsal root zone 'most median |iart of medial portion of dorsiil funiculi; w IT, middle root /.one. (After 1'. riechsiK. Neurol. (Viitrallil., Leip/.., lid. ix, ISIIO, S. 78, Fig. 8.) and not to the former. The tIee!,' Hell Kij; COl d. t th* wl zone." »1> of V ^»l-^ CiUoLPINCi AN1> CHAINING TOGKTHKIl OF XKUUOXKS. 42t.t Fleclisiff of a iiii, is that immediately adjacent to the m<'dian sei)tnm, an area which cori'c- .sponds to Fieclisig"s iiii'didiir Z.'li tlif s] iiiiil oml at the level nf the third linnliar lUTVi'. (( ir. lateral (lor^al mot >n:ic : hW. ini'iiial ilnrsal i t /mii' : .-.v. median n)iniiarliiieiit nf the latter : mW. iiiiddle i t zone ideiiciieraled ). heyiiiniiiK tahes: '' "'• ventral i t zone; /'>'. lateral ii.vraniiilal trael thinks has its origin in dorsal root tii)res) is made up of medullated axones. which tu'c processes of cells situtiti^d in ) 1 1 1 3» ' '! \ Ii m \' i5 I! 4;5(» TllH NEUVOUS SYSTEM. tlu' dorsal lionis of tlie f^ray matter of tlic spinal oord.* This view is ill (lircft contradiction to the results of tlio studies of secondary dcju'cncrations, and of those in which (Jolyi's method has been emjiloyed ((vV/r infra). Von Kechterew further thinks that while a part of the lihres t>f (xolTs bundle run all the way to the medulla obkmji-ata without interrujition, another portion is interrupted and continued ujiward only l)y the intercalation distances. In the thoracic and cervical cord there are no medullated fibres in the dorsal regicm of the dor.sal funiculus (Fig. 284, />), nor are there any in (he middle region of each dorsal funiculus (Fig. 284, a) ; the only medullated fibres present are situated in a narrow stripe near the median sejjtum (Fig. 284, (/l.and in a. somewhat broader stripe along the dorsal horn (Fig. 284, c). In the most ventral region of the funiculus these medullated areas go over into one another. The non-medullated regions are continuous with one another at the dor- sal perijihery. In fo'tuses 28 cm. long the appearance of the dorsal funiculi in .'dl regions is very different from the foi-egoing. In the lumbar cord, which has by this time grown to be considerably larger, not only is the dorsal portion, which before was non-medullated, now regularly studded with medullated lil)res (Fig. 28")). but the ventral portions have many juore medullated fibres in them than before, the individual medullated fibres now standing much closer together !l :1 ■: ■:1, r *' < , ' :t:i ■W ;lf, -, Ml V 1 1 1 TI um L 4:52 TilK NKU vol's SYSTEM. tliMii ill tilt' fd'tiis 'J\ cm. luiiy. tilt' new lilircs cvidfiitly occupying tlif iiitt'i'isimocs iM'twccii the oltlci' ones. It is dhvioiis, tluTeforc. tli.'it tiiis second system of lilires occiijiies tlie wliole cross section ot' tlie liiiiil)iir portion of llie dorsal fniiiciiii. aitliouuli Trepiiisi tliiit the dorsiil rejrioii of the dorsiil fnnicuhis contains more of tlie fihres of the new system than does the ventral re■- /^t -■■'<:;. ■■;?'??■ X -^: H V: Vm. '2S((. (2S (•111.) >.^ -M M •jsr •,'S (111. 1 (Fig. 'JS)'.. /;i. a latei'al dark part (Fig. 2S(). o, and a medial dark [lart (Fig. 2S(i. (I). Tn the cervical cord in the ftetus i?S cm. long tlii' fasciculus ora- cilis (Fig. :iN7. fM. owing to the small number of medullated libres present in it. appears light, with the exception of a narrow strip neai' the median septum (iMi •2S7. (h a reiiion win ch. it will be =x. ■?€ii m ./ m^-: -^w (iHTIlHlJ dl" NKl'UoNKS. 4.S3 nralU'il. cuiitniiicd some iiicdulliitt'd tiln-cs iii tlu- I'm-Ius ^1 ciii. loiijf. Tin- (liirk stripf of (loUs fiisciriiliis passes over at tlic most vciitml rt> cm. long- there is seen to be one area which in Weigert preparations takes a very dark stain, while other jiarts are stained of a light color (Fig. 2SS). This is owing to the fact that in the dark region there has been a great increase in the number of niedullated fibres. The new fibres (those of Trepinski's third system) occupy on the cross section stained by Weigert's method the greater part of the luinbar dorsal funiculus I Fig. 2SS, (•). The area in which they are distributed is limited dor- sally by a ciu'ved line, behind which the doi'.sal funiculus looks light (Fig. 2SS. h). Near the median septum too there is a light stripe (Fig. 2SS, a), which is continuous with the dorsal light region; 29 Fio. !iss. :r> ciii.^ !!^ V, i iU THE XEUVOL'S SYSTEM. l)o.si(l(>s, tln' jurist vofiti'iil part of llio lmiil)iir dorsiil funiculus (Fij''. ixs.f) looks Ii<,'lit in roniparison witli tlu- ilark ana, but iiciv liie Iciiiai'cation is not sliarp. In tho thoracic cord of a fo-tus ,'{5 cm. ]on ^'.''r: I'lc. ssn. i3.T (111.) "->^ Fi(!. ^iin. i;?.-) ciii.'i (f(etus "JS cm. long), so that the outer dark region now includes the middle light sti-ijie of the earlier developmental stage. The medial dark part (Fig. '2Si). the lateral dark area. The latter does not. however, reach tlie dor.sal periphery. Owing to the narrow limits of the medial dark area there is a much more extensive light area (Fig. 'JS!I. a) in the thoracic cord of f cm. long the third system of fibres is distributed in the greater jiart of tli(> fasciculus cuneatus (Fig. iilll, c). only the small dorsal portion of the same (l''ig. 'J!l(i. / in fibres : this dorsal jiortion is now of a light color, although in fo'tuses 'JS cm. long it was just as dark as the more ventral portions of the fa.sciculus cuneatus. The fibres of the UKoriMNd AND ('IIAININ(} T0(H>:THI:I{ of N'Rl'HON'KS. 435 tliinl system an' (listi'il)uti'(l also in tin- medial portion of the fascic- ulus j^raeilis (Kiff. •J'.Mi. ih, as is s1i(»\vm l>y an increase of tlie medul- lated til>res situated there at this (levelo|imentaI sta;ie. This re^jfiou of ({(dl's t'aseieulus is now closely studded with medullaled tihres, aiuHooks darker than the more lat«'ral portions of this fasciculus ( Fiti'. -!•(•, (I). ( )n compai'iuy the dark medial i)art of ( JoH's fascicu- lus in the fu-tus .'!,■) cm. lonj,'- with that of the fo-tus "JS cm. lonjf, it will he seen that the reffion at the later period, thou^jrh considerahly lar^^er, shows tihres standing much more closely together than in the earlier sta}.fe. The medial dark ]»ortion of the fasciculus ^'i-a- cilis is continuous with the dark [xirtion of the fasciculus cuneatus at th(! ventral rej^ion of the dorsal funiculus. The fourth svslem of Mitre; accordiui'' to T I'epnisKi, lias com- pleted its development hy thi' lime the fcetus has attained a lenf,''th of 42 cn»., for at this period, he states, all parts of the cross section of the dorsal funiculi are evenly .studded with meduUated nerve lihi'cs. The chanji'e in the ai)pearance of the ci-oss section is evidently (ha* to an increase of meduUated iihres, whii'h have con\e in to occu|)y the lijrht reffions between the Iihres already present in them at ear- ier develo) mental .stafr*': It is accordingly easv to deline the areas of di.sli-ihution of the Iihres of the fourth system. Thus in the lumbar cord the nerve fibres of this system occupy the dorsal por- tion (Fiy. "JSS. fi). a medial rcjij^ion (Fi^;'. "JSS, <»), and a ventral field iFijj^. 'iss. /'i of the dorsal funiculi. In the thoracic cord they spread out in the dorsal reissauer's marfi'inal zone, an area wliKli ill realitv iM'loiiirs to tl le lateral funiculus of the coin d. V. ven in fo'tuses JT cm. 1 onavinj^ out Lissauer's /.one, it is easy to distinffui.sh in the dorsal funiculi four embryonic systems of nerve fibres. The area of distribution in the cross section corre- siiondin"- to each of these fibre svstems can. he thinks. b(> established wi 1. th exactness, in .s])ite of the fact that tiie fibres of diil'erent systems nix up with oiu^ anotiier. for each of th<> systems when it apjiears cads to an alteration in the ai)pearance and memi)erment of the dor- sal funiculi. F]ach of the four systems lies, in the uppei- rej;ions of the spinal cord, partly in the fasciculus cuneatus, partly in the h r ?i 1 1 ■■ ii: si r. li^ V IMAGE EVALUATION TEST TARGET (MT.3) 7 ^ ^ /. {/ .v'^A t^/- 1.0 I.I •- lis III 2 2 ^ us 12.0 ii \M IIIIIM III 1.6 Photographic Sciences Corporation 33 WEST MAIN STREET WEBSTER, NY. 14SB0 (716) 873-4503 ^^ iV ^\ r^-^^A-^^ rv^ ^ '■ i I 48fi THE NERVOUS SYSTEM. fasciculus gracilis, aiid since nicdiillatiou is conipktcil in the fascic- ulus jjTaci lis at the same iK-riod as in the fasciculus cuncatus, it is ol)vi()iis that from the study of devel(>i)nient alone (lulTs fasciculi are composed of the same embryonic lihi'e systems as are BurdachV fasciculi. Trepinski, like Flechsijr. believes that the distribution of the cmbi'yonic fibre systems atfoi'ds thi' clew to the varyini;' pictures met with in tabetic degeneration. In his article he gives a number of examples of cases of tabes illustrating his view. And it must be granted that if his drawings are objective, the parallelism between the tabetic degeneration and the stages of niyelinization is remark- ably striking. No student of tabes, at any rate, can afford to over- look these studies of Tre])iiiski. It would lead us too far if we attempted to compare the findings in cases of tai>es with the findings in the embryonic spinal cord. One example from Trei)inski"s article Fi(i. :2itl. may. however, be given. In i case of l)eginning luml)ar tal)es Tre- pinski found, in addition to a degeneration of Lissauer's zone and of certain i)arts of the gray nuitter of the cord, a moderate degeneration in the middle region of th(> doi'sal funiculi (Fig. 201. o. The dorsal parts of these funiculi (Fig. ^'M. I» look healthy, as do the medial regions connected with the dorsal i)arts aiul lying close to the me- dian .septum (Fig. 2'.)1. a) and a ventral field i.i the dorsal funiculi (Fig. 2\)\,f). This distribution of degenerated fibr<>s in the dorsal funiculi leads to a Jnembennent. reminding one innnediately of that met Avith in the s])inal cord of a f«rtus 35 cm. long (cf. Fig. 2SS), with this difference, that the i)ortions which wiM'e of a light coloi' in the f«ctal dorsal funiculus ai)pear dark in the diseased cord, and rice rema. It will be remend)ered that in the fietal dorsal funicu- lus this special appearance was brought about by the ripening of GROUPIX(J AND CHAINING TOGETHER OP NEURONES, 437 tlie tliird sj'stein of fibres. Tivpiiiski believes that tlie meinber- iiieiit in the diseased cord in this case must, tlierefore, be due to the defeneration and disajjpeailtnce of that system of fibres wliich called forth the membenneiit in the spinal cord of the fo'tus. He concludes, therefore, that in this case of tabes the degeneration has attVcted the third embryonic til)re system alone. That in the de- generated area many healthy nerve fibres remain is easily ex- plained, for in among the fibres of the third system there exist fibres of the first and second system. If the fibres of the third sj'stem alone be diseased, then the fibres of the other system shoulc) •".main over as healthy fibres in the degenerated region. He cites a series of interesting cases which he has met with, and illustrates them by drawings of the sections, but for these the reader must ccmsult the original article. 1^' I I i| :■ ■ k tw m i »ii / 'iiiii m I :' i hi . 1 * dv'-- ft 1 ^ ■ m CHAPTER XXXIII. CEXTRAL AXOXKS OF I'KUIIMI I;HA L (KXTUIPETAL XErROXES. {('tmtliiKi'd.) Studies of sconndary (IpgctuTiitiiiiis — I'lxporiiiR'iitid invcstip^ations — Li'^iioiis of single dorsal roots in liiinian bt'in^'s — Stiidics of oaso.s of transverse lesioH of the spiiuil cord — Fibres eoiirles,Jihri'H longiies vt fUiirx rnoij- cnuPK of P. Marie — Ascending degenerations in dorsal fnnicnli — De- scending degenerations — 'I'iie coinnui of Schultze — Fibres eiiihi(j('iii-.s of I'. Marie — Trioiigfe mMio)i of (Jomljault ct Pliilipiie — Flcclisig's o -al centre — Descending septo-nnirginal tract of Rruce and Mnir — Descend- ing limbs of dorsal root fil)res — Axones of siiinal cord cells entering dorsal funiculi — Kxcentric position of long fibres — Ascending endoge- nous fibres in dorsal funiculi — Ana'inic necrosis following ligature of abdominal aorta — Fasciculus dorsalis projirius — Terminals of dorsal root fibres as studied by Marchi's method. The methods of studying secondary dt'genei'iition tipijlied t(> the dorsal fasciculi have sui)i)lii'd us with a large nunihcr of facts of the highest degree of iniportiince. In animals, if one or more dorsal roots be cut between the spinal ganglia iind the spinal cord, the intramedullary continuations of these fibres un- dergo secoiulary degeneration, ami can l)e studied later by Wei- gert's method or, better still in some cases, by the method of Marchi. In this way it is possible to determine the exact ])osi- tion in all parts of the spinal cord of the intrairieduUary con- tinuations of any desired dorsal root. Without reviewing in detail all the individual researches made in this field, the results in general may be thus stated : After section of the dorsal root of a spiind nerve between the ganglion tiiul the cord, both the lateral and nu'dial bundle of fibres (seen just after entraiu'e) inulergo complete degeneration iind can l)e easily studied. Immediately above the level of entrtmce of the nerv(> root concerned there is degeneration in the entry zone. If the lesion be situated low down in the spinal cord, an examination of transverse sections made at different levels up the cord shows two things: (1) A 438 mi (illoriMNG AND CIIAININ'C} TOCJHTIIKU OF NEURONES. 4;5t) 2)roi,MT.-(.sivo (liniiniitiou in tlu' muiihcr of dcfjenerati'd fibres as the cord is ascomU'd ; {'i) a gradual chaiijic in the position oc- cupied by the degenerated fibres. Tlie first observation proves that the fibres of a dorsal root wliich ascend in the cord stop at different levels; the second proves that fibres, which low down in the cord are situated near the gray matter in the entry zone, 1 igher uj) come to occupy a position more dorsal and medial, gradually approaching (i oil's fasciculus, and in the case of the sacral roots, for exanij)le, forming a part of it. All the evidence from the study of secondary degenerations goes to ])rove that the fil)res of the fasciculus gracilis in the cervical region repre- sent the long intramedullary continuations of dorsal root fibres which in the sacral and lumbar region were among the fi])res of the fasciculus cuneatus. Each dorsal root as it enters the spinal cord pushes the fibres of Burdach's fasciculus in a dorsal and medial direction, so that the long ascending fibres are neces- sarily successively more and more displaced toward the dorsal mcclian sulcus. These relations are beautifully illustrated by the experimental work of Singer,* Kahler,t Tooth,! Singer and Miinzer,** aiul others. Singer and ^riinzer cut the dorsal roots of the twenty-sixth, twenty-seventh, and twenty-eighth spinal nerves on one side, and also the dorsal roots of the twentieth, twenty-first, and twenty-second nerves of the same side. After the aniimd had lived long enough for degeneration to become marked, it was killed and the degenerations were studied in sections made at different levels (Fig. •i'.^'i). A section made just abovi' the entrance of the twenty-sixth root shewed degenerated fibres in the \\hite matter immediately adjacicnt to the dorso-medial * Singer, J. Uebcr scciiiuliin' Dcgi'iuTiition iiu Itik-koniiiurk des IIiiikK's. Sitzungsb. (1. k. Akad. d. Wissonscli.. 3Iiitli-i' tiirw. CI., :?. Abtli., Wicii, IM. Ixxxiv (1882), S. 31)0-419. + Iviihler, O. Uebcr die Veriiiideruiigen, welciie sieh iin IJikkeninarke in Fiilse einer goringgradigen roinpression ontwickoin: notist eineni die se- I'lindiiro Degeneration ini Hiiekenniarke des Ihindes lietrulTenden Anliang. ^tsohr. f. Ileilk. Prag.. I?d. iii (1882), S. 187-282. t Tooth, 11. H. The (Joiilstonian Leetures on Seeondary Degeneration of the Spinal Cord. I?rit. M. .1.. Loud. (18H<(). i. pp. TW ; 82."); S,^):!. Also Re- print, London (J. A. Churehill). 188!». * Singer. J., and E. Miinzer. Heitnige ziir Anatoinie des Centralnerven- systenis insliesoiidere des Iliiekenniarkes. Denksehr. der Wiener Akad., Bd. Ivii (1S!):J-"!)!), S. 501). r I ifct -'*• \: if ti I > 440 TIIH NKIlV^ors SYSTEM, surface of the dorsal lioni. At a little lii<,'iier level below the entrance of the twenty-second dorsal root the diseased fibres were more separated from the d(»rsal horn iind occui)ied a trian- jxular area not so very far from the dorsal nvdian sulcus (Fiiiii;. I?(»r> anil lidti, Kifis. 20S to 212. ) (/, level of tin' twi'nt.v-sccimd si)inal ncivc ; /), cross section of the cord between the level of the twentieth and tweiit.v-second spinal nerves ; c, transverse section throu^'h the cord at the level of the eifjhteintli spinal nerve ; il. transverse section of the cord in the thoracic region ; c, trans- verse section of the cord at the level of the intuinescentia cervicalis. roots (not cut in the experiment). Sections mtide through the cord iit iiny level between the entrance of the twentieth and twenty-second dorsal root showed the degenertited fibres of the twenty-sixth, twenty-seventh, iind twenty-eighth still iiciirer the mediid septum, itnd in tiddition new degenerated fibres of the twenty-second and twenty-first roots just dorso-meditd to the dorsal horn of gray matter (Fig. 20t>, //). Higher up, tit the level of the eighteenth spinal root, the degenerated fibres be- r IH GROUPIX(i AND CHAINING TOIJHTIIEU OF NEl'RoNKS. 441 lon^Miij,' to the dorsal mots wliicti had lu'cii i-ut liiji'licst up wt're soiiH'wliat si'parutt'd from the dorsal lionis and had coiuo to occupy the middle portion of the dorsal funiculus, although they were still se})arated by undegenerated fibres from the hundle of degeneratcil fibres near the median septum, the long continuations of the twenty-sixth, twenty-seventh, and twenty- eighth roots (P'ig. W'i, (•). The lateral bundle decreased pro- gi'essively in size in the sections taken from parts of the cord higher up. Sections made through the thoracii^ cord showed an ever-decreasing number of fibres in both bundles, which now beg.m gradually to apiJi-oadi one another (Fig. 'i'.^'i, iR'liuiijj. Jena. IHSIJ, 8vo. X O/i. rif. * I'fiilTor. H. Zwoi Fiillc von ]„"''imin,c; der imtorcn Wurzi'Iii des I'h'.xus ln'acliiali.s (Kluinj)ko'.sclie Liiliniiiii';). Doiilsche Ztsclir. f. Nervenli., lieij)/,., Bd, i (1891), S. 345-!]:0. II rioiid)ault, A. Bull. Soc. anat,. dc Par., t. Ixvi. 1891. ■'^ Sottas, . I. Siir l\''tat di' la inocllf ('■[linii'rt' dans deux cas dc conipiv.'*- sioti d(>s racinos postericurcs. Coinpt. rcnil. Soc. do hiol., Par., !». s., t. v <189.'}). pp. 246-248. — Contributinii a IT'tiidt' dt'sdi'grni'rt'sccnccs dc la tnoelk' con.sr'cutivos aiix lesions des racines posterieures. Kev. de nied.. I'ar., t. xiii (1898). pp. 290-;{i;5. ^ Mayer, f". Zur patlioloijischen Anatomic dor Kiickeninarksliinter- striin-,'e. Jaiirb. f. Psychiat.. Eeipz. ii. Wien, 15d. xiii (l.S!»4), S. .IT-IOT. J Xagcotte, .1. Ktuile sur un cas do tal)os uniradiculairo tdiez iin paia- lytiipio general. Hov. neurol.. Par., t. iii (IS!).')), pp. :!:{?: ;U)9 : 401. I Soiiqiios. \. Dogeiieration aspondanto dii faisceau do Biirdacli el dii faiseeau cuneiform, eon.seeutive h Tatrophip d'une racine eorvieale post^- rieuro. Cunipt. rend. Soc. do l)iol.. Par., 10. s.. t. ii (18!),')). pp. 40T-410. % Margulies. A. Zur Eolire voni Vorlaut'o dor liinteron Winv.oln beim Menschon. Neurol. Cent ralbl.. Loipz., Bd. xv (1896). S. 347-;551. ** Dojerino .1., et A.Tlioinas. Contribution a Toludo du tni.jot intra-ni^- didlairo de.s raeinos postorieures dans la region oervicaloet dorsalo suporioure de la inoelle epinioro; sur I'etat do la luoolle opinioro dans un cas de paraly- .sio riidicidaire inleriiMiro du plexus braehial d'originc syphilitii|Ue. Conipt. rend. Soc. de biol., Par., 10. .s., t. iii (1890), pp. (iT.'»-679. (iUOUHNO AND CIlAIMXiJ T()(}1;tIIEU OF NHrUONKS. 443 iiuinhcr, hiive l)t'i.'n very cari't'iilly .stiulictl, in two instance's at least, l)y Murclii's mctiiotl.* Tin' fintlings tlins far in liuniaii cases prove tliat in man, as in experinientul aniinnls, the root lil)res on entrance occupy a tolcral)ly wide zone in tiie fasciculus cuneutus, just dorsal to the <,'ray matter of the dorsal iiorn, as this is the urea whicii is found de^n'iu'rated at the level of a diseased dorsal root. In sections made at hi autopsy with such a lesion should be removed carefidly in toto, preserved in I cn-iier-cont formalin or frcsii Jliilier's fluid, and iian.ded over to a skilled miirologist for cxaniiualiou as soon as possil)le after its removal. m^ >lili i. 444 TIIK NKia'ors SYSTKM. ever, tliat iiitlividuiil til)ri's iiuiy disohcy tliis general luw of dis- tril)Utioii.* Tlic cliiiugc ill the t'oriii of the dt'jrt'iu'ratcd area, as well as ilif altoratioii in j)ositioii, is worthy of note. The case dcscrihi'd l)y .Mar<{uli(''s may lie ilioson as (yi>ical of the chiss to which it belongs. If the acconipanyiiig figures (Fig. "^!i:{) and their leg- ends he consulted, the relations at ditTereiit levels above the site of lesion will l»e clearly luidi'rstood. At the level of lesion (sixth thoracic root) the area corresixjiiding to the entry zone shows degenerated fibres ; the medial displacement with arrange- ment of the degenerated fibres in the form of an L is illustrated in the next section (level of first thoracic) ; still higher (level of seventh cervical root) the degeiicrate(l fibres, of which there are now many fi'wer, occu])y a triangular area, and in the liighcst section figured (level of third cervical root) the tyi)ica! narrow dorso-ventral l)an(l lying close to the paramedian septum is clearly visible. Thus far in human cases, even in those studii'd by Marchi's method, continuaticms of dorsal root fibres into the ojiposite dorsal funiculus by way t)f the gray commissure have not i>i'en described, thougb some of those who have experinu'iited ui)on animals assert that in them such fil)res exist (Oddi and Kossi.t Loewentbal,Jl'aladino,'*an(l l*elii/zi||). The vcit careful Knglisli investigator Mott, however, could not find such fibres in the monkey's cord. Th'.' studies of secondary degenerations following fniiisrcrse Irsioii i)f fli'' nird from compression, trauma, and other causes, while of the jrreatest service for the information thev have alTorded concernin}; the tracts in general which ascend and de- * Tlu> stuilics of SchiilTcr with Jhirdii's nii'tlKul (Aicli. f. inilv»'l nf tlu' sfvoiitli (1 rvical nmt ; l>. tnnisviTsf .strtimi at tlii' Ivvcl of t'U- tniiicf of tile tliird icrvical root 14 3 '* ■' in; TIIK NllUVors SVSTKM. sct'iid ill tlit'conl, iiiitunilly <1<> nut yicM as siitisfiH-torv tliita for ilciliiclions (■(iiicci'iiiii'; the intriiiiifdiillarv i-oiirsc of tlic dorsnl root lil)rt'rt as do the " piircr " cases in which the root tihrcs ahiiic arc injured. Still tlicyhavc su|t|)licd us witli a mass of conlinualory cvidi'iicc of very hii,'h value, and hesides, in sudi east's certain fi-atures are met with which demand especial con- siih'ratioii. Since the resi'arches of SchielTerdi'ekcr * an enormous num- her of eases have heen studied hy many din'erent invest i<,'ators. The individual researelies which concern the dorsal funiculi need not l»e referred to here, since several excellent ri'views of the status of this siil>jt>ct are extant — notahly those of Tooth,! Uarliaeci,J Ivetllich,'* von lieuhossek,|| Schnuius,-'' and I'hilippe.^ licavinj; out of consideration here the th'^enenitions in the ventral and lateral funiculi of the cord, the statement may 1m' made that after total transvi-rse lesion of the spinal cord the d(U'sal funiculi show, in athlition to the chan. aiul U.l. hix (1S77). .S. \V:\. t 'I'liotll, ('/'. (•//. I Op. fit. * Ueillii'li, !•!. I>it' iiintiMvii W'ur/flii dcs IJiU-koiimnrkcs imd die piillKi- iogisclit' Aiiiitoiiiit' dor Tiibcs ilorsalis. .\rl). a. d. Inst. f. .\nat. ii. IMiysinl. (1. CiMitraliH'Wcnsyst. an d. Wien. I'liiv., Leiiiz. u. Wii-ii. (iJSir^), S. l-o'.2. II Op. rif.. .S. 2Si). •^ .'^ciimaiis. V. Sckiiiidiiro DoirfncratioiitMi in; Ki'ickfiimark. .Articlo in I.uliarsi'ii-Ostcriatf's Krfjol)!!. d. spczitd. path. Morpliol. u. I'iiysiol. di-s .Meu- solu'M mid diT Thii-ro. Wiosljadcu dSOti). S. (t:?!. Pliilippc. CI. ('oiitrilnitiiin a IVtudo aiiatoiiiiiiue ot eliiii((iii' du tabes dorsalis. I'aris, l!S!)T. : Ml OUOl'I'INO AND <'II.MNIN(i 'nXiKTIIKK uh' NKriJONKS. 417 ifltT tilt' ciilnmct' of (Idi'siil roots uIjovc the lesion, show iiikIc- ii«'?ifnit(Ml lihrcs ill the ciitrv /.one mimI lalt'ral portion of tiic fasciculus ciiiiciitus. The /one of iiii(h';;ciicriitcti fil)rcs iii- cn'iiHcs pro^jrcssivdy in size in sections cut at hi^^her and hi^'hcr h'Vels, and tlie area oeenpied liy the dej,'e lie rated fihres as pro- ^M'cssively th'creases in size, and at the same time heeomes more and more limited to the dorso-medial portions of the dorsal fnnienl- of t he t\v(» sides, in the cervical ref^ion thedcf^cncrated lihres are entirely or almost entirely conlined to the fasciculus j^racilis, and if the lesions have heeii very low down (say helow the level in which the fasciculus j^racilis coiiiinences) they will occupy only that portion of the fasciculiiH ^'racilis adjacont to the dorso-niedial septum. 'I'he de^'cneration in the fasciculus jrracilis can he followed up to the incleus funiculi j^rai'ilis in the medulla ohlontfata. Su(di tlndin^fs prove the falsity of the doctrine of the ahsoluto anatomical individuality (d" the fascicu- lus ;^racilis. If the lesion, on the other hand, he situated in the upper thoracic region, in addition to the dejreneration of the fasciculus trrai'ilis, there may he found in specimens studied hy Marchi's method, at a suital)le period (death within three months) after the lesion, dejj;eiierated lihres also in the medial and dorsal por- tions of the fasciculus cuneatus, thoU',di the lihres are so few in nuniher that in old cases studied hy W Cijfert's method the fas- •iculus cuneatus on ea(di side may aj)pear almost or entirely normal, 'i'ransvei'sc lesion of the cord in the cervical rej^ioii always results in de<,'eiu'rat ions in the fasciculus cuneatus whi(di, thoii^di diniinishin<^ in volume, may he followed up to tiu' nucleus funiculi cuneati of the nu'duUa ohlonjrata. Since eacdi dorsal root, as is evident from the forej^oiii"; studit's, contains fihres of vi'ry dilferent leiifx+lis, we arc justilied in speakin<; of "short " dorsal root lihres, " lonu " dorsal root lihres, and dorsal root lihrt's of " intermediate " lenj^th {Jilirrs rtiiir/rs, Ji/tffs liini/iifs, >■/ Jihrcs nini/rinirs of V. Marie, Ki^f. '■>'.*{). 'Vhv root fihres are distiii<:uishahle not only hy their len^rth, hut also by their topographical relations in the dorsal funiculi, and their torminal distribution in the j^'ray matter of the cord and medulla. The areas of secondary dejieneration in the dorsal funiculi /ir/dir the level of a transverse lesion ((leseeiidinj>' secondary de<.foneration) also vary in foi'in and extent accordinj^' to the 11 mi ■a*: ' \ ill i nm ^■ia TIIK NEUVOIS SVSTKM. level of tlie injur to the s])iiial conl. In 1S(S;5 Si'linlt/A' * (U'S('ril)e(l a di'sct'iul- iuil (leini)icssii ,1 111' tlici-onl; WciKi'lll'al pripiinitioii. (After S. Koscnliiiiii. .Inhiis Iloiikins Ilnsii. Itiill., vol. ix. :mal(iiiiit!il iiiiiiil)ir, Sept. - Oct.. ISitS.) A, level (if the fiiiirtli tlwiraeie se.miieiil ; li. level uf the tiftli tliiiraeie segment ; ('. level (if (lie sixth thdl'aeic segment. 'I"he pdsitioii (if the (leKeneiatiiiK ((itiiiiia of Seliultze is very evident. /■'('/.<, faseieiihis eere- hnispiiialis lateralis, alsd dejieiieraled. sixth thoracic segments. IJelow this level it could not be fol- lowed. Tlie form and position of the comma in the fasciculus ouneatus parallel to the meditil inar\ k *■■> ■ i 1 I ■ 1 1 i' 45(» THE NERVOUS SYSTEJI. ^Tiiy matter is well illnstniti'd. Tlic thicker licacl end of the coinniii is directed toward the ^xwy matter, tlie thin tail toward tiie (h)rsal surface. \\'hile some investifjators (Scliultze, Hruns, v. Lenhossek, Fhi- taii, (iiese) have hehl thait the comma corresponds to descendinjj tihres from dorsal roots, others ('I'ooth, Marie, Daxejdyerjjjer, (iom- ])ault and IMiilippe, Diifour, Iloche) think that the medullated axones to wliicli this area corresponds represent lihres entirely independent of tiie (h)rsal roots, and that they have their cells of origin in the gray matter of the spinal cord itself. The comma would, according to the latter view, re])resent a longi- tudiiud association tract connecting ditferent levels of the gi-ay matter with one another. On this supposition its fihres would be intrinsic to the cord itself {Jihrcs rui/oi/e/ics of I*. Marie).* The comma appears to have never been observed below the level of the ninth thoracic segment rntil the recent study of Jloche,f in which that ol)server, by means of .Marchi's method in a case of compression at the level of the seventh thoracic segment, followed its fibres, though the commalike arrangement soon disai)]»eared, as far as a point between the third and fourth hunbar segments. He was able, too, to deter- mine l)y means of longitudinal sections what became of the fibres of the comma. They could be followed as fine dotted fibrils passing oblif|uely into the gray substance. In this, how- ever, they must (juickly change their plane, for lloche could never follow a tibril to its exact termiiuition. The long extent of these fibres in the dorsal funiculi (through at least eight seg- ments of the spinal cord) is, as lloche suggests, scarcely in ac- cord with the idea that they represent descending ])ranches of the dorsal roots. In tlie second case of compression at the junction of the cervicai and tiioracic cord, lloche followed fibres from the comma as low as the level of the twelfth thoracic seg- ment. Longitudinal sections in this case showed the degener- * Marie. P. boi;ons siir Ics iimliidics ilr la iiioellc, H. Par. (ISn2). (G. ^hlss(lIl). — I)e Torifiinc ('xoi^riu'du I'lidiiffriii' dcs li'sioiis du oimloii jKistc'ricur I'tudic'c's conipunitivoinont dans Ic tabes et dans Ic ])cllaji;re. Seiiiaiiii' iiit'd,. Par., t. xiv(IH04). pp. 17-20. f Hoclie. .\. Uebor sccuinlilro Dcjiciicratitui, spccifll dcs (iowors'scheii lUiiidols iiebst Bcmcrkunpeii uebor das Vorlialtcii dcr Kcflcxe bci ('i>ni](r('s- sion dcs Kiickcmuurkt's. Arcli. f. Psychial. u. Ncrvcnkr., IJerl., Hd. xxviii (18'JU), S. olO-r)43. iH- (iiioupiNO AND criAiNiNO toof:tiier op neurones, 4r.l uted fibres nuiuiii^ into the nucleus dorsalis (Fig. 20(i). Maim * advances with much reserve the hypothesis tliat since it extends tlirougliout the whole thoracic coril, dimiuisliing progressively m: ^ ^ -~-v VM'J'^'' ■' v^'M ■ 1 ■ . i t ' ' : ; mi ' '''.-'it ' ." ■ • ■•'.■:•'■ .' .1 ■ ,1 Flart to short jiatlis oC the t'ascienli i)ro|)rii ; /*, sni)stantia ^risea containiiif; the nucleus (h)rsalis (larkii ; c, dorsal fnnieiilus. The de>!enerated lihres which lie on the rijrht-hand side near the peripher.v helon;; to the path which lower down forms the oval held of l''le<'lisi<;. The degenerated lihres fioii'K toward the snhstanlia Krisea form, on a correspondinj; cross section, the well-known c zui' Leiire von iI^t siiiiiMJen Hemi[iluj,Mo. Deutseiie Ztselir. f. Xervenh., Leiii/., I'xl. x (IS'lOi, S. l-()(i. f Zai)pcrt, J. lieitnijjo zur abjstiMf^ciKU'ii IliiilerslraiiLCsdeLieiieralioii. Neurol. Centrallil., I-ei|iz., i'.d. xvii (ISnS), S. 102-107. ' ( ] . i. i H 452 Till'] NKRVOrs SYSTEM. IJiirbiicci,* ill wliich there was compression at the level of the sixtii iiiid si'veiith thonicic roots, followed by death at the end of forty days, he found just beh)\v tl.e lesion a ratlier dilfuse degeneration in the dorsal funieuli. Lower down he found in the transverse sections a strijje in the lateral part of the fascic- ulus cuiu'atus on each side, while niuoli lower still tlie degener- ation was limited to a narrow stripe along tlu' dorsal median septum. Barbaeci assumed (almost ( 'I'tiinly erronecuisly, as will immediately l)e clear) that the degeneration below along tlu' septum depeiuled ujjon the waiulering ovi" toward the me- dian line of a certain number of fibres from the comma higher up. Tlie degeneration liere mentioned as situated near the median septum has also been observed l)y Keijlieh f ami by Daxenberger.J The region concerned togetlier with a peculiar triangular field carefully described l)y (iombault and Phili])pe* does not degeiu'rate after injury to the dorsal roots, nor does it degenerate in an ascending direction after lesion of the gray substance below, (iombault and IMiili[)pe conclude from their studies that tlie fibres adjacent to the septum, the so-called do I'Komed idles Sdcralbihuh'l of Obersteiner (those of the two sides corresponding to t]u> rrtifnini oraJe of Flechsig), form at the level of tlie lumbar enlargeniciif and a little below tliis level an oval fasciculus; that b uer down in the conns meduUaris the same fibres are gro.iped in the form of a * Op. cit. ■f Kodlich. E. Ziir Vcrwendimg der Marc'hi'scheii Filrbuiig hci patliold- gisclicu I'riipiiralcii (k> Xcrvoiisysteiiis. ('outrall)l. f. Norvcnli. u. I'sycliiiil., Cobk'iiz II. licipz., n. P., Hd. iii (1S92), S. 111-115. Sec ulso, Die liiiitLTun AVurzola dcs RiickemiiHrkes und die imtiiol()gis<;lie aniitoinio iu') ; and tliat tlicy boloiij^ to the association systems of the dorsal funi(!uli, and do 7iot n-prescnt continuations of dorsal root fibres. lloche's study* of two cases of compression (one at the level of the seventh thoracic, tlie other at the level of the eif^hth cervical segment) has gone far to render our knowledge of the fibres under consideration more satisfactory. By Marchi's meth- od he has been able to follow the degenerated fibres in both instances throughout the whole thoracic cord into the filum terminale. In his second case degenerated fibres of this group eoidd be followed through no less than twenty-three segments of the spinal cord. These cases are so im])ortant that they merit consideration in some detail. In IIo(!he's first case (compression at the level of the seventh thoracic segment) the degenerated fibres belonging to the sys- tem under discussion, even just below the lesion, are situated on the dorsal periphery of the cord and are entirely distinct from those of the comma (Fig. ;^97). A little lower they approach the dorsal median septum (without, however, leaving the dorsal periphery), which they reach at the level of the eleventh tho- racic segment. The fibres lower down begin to be arrangetl along the median septum, part of them renuuning at the dorsal ])eriphcry, however, immediately adjacent to the septum until the level of the second lund)ar is reached. From the level of the third to that of the fifth lumbar they no longer reach the dorsal periphery. But from the level of the fifth lund)ar down- ward as far as the filum terminale the degenerated fibres of the two sides form a small triangle, the narrow base of which corre- sponds to the dorsal periphery of the cord. Tiiroughout, the comnui and the fibres of this buiuUe are entirely separate and distinct. They have, IToche emphasizes, nothing to do with one another. It will be noticed that the degenerated fibres from the third to the fifth hnnbar segment correspond exactly to Flechsig's rriz/nnii or/ih\ and tiiat from the third to the * Ildclic, A. Ucbor Verlniif imd Etuliufiinijswcist' ilcr Fascrn ties oviilcii Iliiiti'rslriiiijfrcldos ini LiMidcmniirki'. Ncuml. Cciitrnllil., Leip/,., Hd. xv (IS'.tO). S. l.'J4-ir)r). — Ucher sociindiiro nojfpneration speeiell des Gowers'st'hcu Uiindcls, Delist I'i'mcrkiiiip'ii ucher diis ^'('l•llMlteIl der noflexo liei fompres- sioii des Uiieki'iiiiiiirkes. Arch, f. I'syuhial. u. NervL'tdu',, Hcrl., Bd. xxviii (ISflG), S. 510-543. J W' it } I I ijif 454 THK XKIIVOUS SYSTEM. I"' I iifth siUTiil sc^mont tlioy corrcspoiul precisely to the trimiffle median of (Joinljimlt and I'liilippe. In Iloche's second ciise (compression iit the h'vel of tiie eighth cervical) it was found that the lihres of the tail ot the eoinma in the upper part of the thoracic cord are intermingled T. via ■■^ys^' ■..> i r. /. ■ M T. .r. T .ri i^feV T. .rii. -'i'?.? L.i. tJ^.:^ L. a If •- L. Hi. I L. iv. \f.' L. I'. 1 s. a:. f^ \ S. ir. S. V Flo. 297.— TIcscciidiiiK (IcKonoriifion bolow ii transverse lesion at the level (if tlic seventh tlicinieic segment. Metlnid of March i. (.\ftC>' 2*'-?^ <»ifo» ^■\ T. XII m- "■,' 4| I,, t". L. 11. C9 Xi. III. L. iv. L. r. s. a. S. III. Fic). 298. — r)(>s('('ii(liiij; 'l''f;'''i<'i'i"H Ix'low a lesion ("('(nuin'i'ssion) of tlip spinal I'ord at flic lovci of fill' ciKlitli ccrvii'al nerve. Atetliod of Marelii. ( .Xfter A. Uoehe, Arch. f. I'.sycliiat., etc., Herl., Hd. x.wiii, IWMi, Taf. .v, I'ij,'. 1.) Ij; U U li ;■?! 'M U ^llilfl V ^ ! 450 TIIK NKHVOUS SYSTKM. (il lii I .f; V with the most vontral (tf the ^touj) of lihrcs, which lower down are coiitincd to tlic (U)rsiil ju'riphcrv of tlu' cord, the rmfnitn (ivdif (»t' Fh'chsi dorsal root tihres run longitudiiuilly. Whether or not, in view of the findings of iloche, Bruce and Muir, and Dnfour in liinnan cases studied since IS!).'), these ob- servers have altered the opinions then expressed. I do not know. The care- fully studied case of K. SchatTer (op. rif.) showed no degenerated fibres in the njedian zone of T""'lechsig. hut this, as Iloche suggests, may be due to the fact that four mouths after the lesion is too late for satisfactory study by Marehi's method. + Flatau. K. Das Gesetz der excentrischen [jagerung der langen Bahnen im Hiickenmark. Ztschr. f. kiln. Med., IJerl., Bd., xxxiii (1897), S. 5r)-li")2. OUOUIMX(J AVI) CIIAIXINU T()(}KTIIKR OP NEUUONKS. 4r,<» Tho (Uw^onditi^ linil)H of tlic liWros of the dorsal roots nuist, liowovcr, occupy some ])osition in the cord. Wlictlicr tlicy iirc dilTu.scly distril)ut('d over the fiisciculii.s cmiciitus or arc limited to the region of the eiitry-zoue or to the third <;rou)) of descend- in;,' llhres (very short liltres) (lescril)ed above, or iinally are inter- mixed with the endo^jeiious descending fibres, we do not know. Serial sections in the next human case of ])ure lesion of a dorsal root, coniin/j; to autopsy at a period suitable for study by the method of Marchi, should settle this nnich-vexed (|uestion. In view, thci, of the extrenu' ])robability that desceiuling endogenous fibres rejdly exist in that part of the cord, the (pies- tion naturally arises, An; there not also ascending endogenous fibres in tin* dorsal funiculi ^ Such a ((uestion could scarcely be answered by the study of degciu'rations following either lesion of the roots or con)])ression of the cord. It could be more satisfac^torily attacked by (iolgi's method, and Uamon y Cajal * and v. Lenhossck f have described the cell bodies of niMiroiu's situated in the dorsal horns whose axones enter the dorsal white funiculi. N'on Lenhossck states that the axones may be mixed with ascending and descending limbs of sensory fibres. The nund)er and course of the ascending cnd(»geiious axones in the cord of the ral)bit ciin be cx(piisitcly established by utilizing the cxperinu'ut of Mhrlich and Jirieger.J ^lilnzer iind Wiener* have denn)nstrated in the rabbit by this method (tying the abdominal aorta and thus causing amcmic necrosis of the gray matter of the hnnbar spinal cord) the course of the asceiuling endogenous fibres of hunbar origin (Kig. 'M)()). While the results of such an animal experiment may not of course be directly transferred to the human cord, still it is in the highest degree suggestive and shouhl put us on the alert for the isolation of these fibres in human beings. It is of no inconsiderable inti'rcst to note that the ascending bundle in the rai)bit occupies a region in the upper i)art of the cord * Hamon y Cajal, S. Xuevas olisorvacionos s(it)n' la estriictura de la mcdiila csiiinal d.. Hcrl, Hd. vii, Siippl.-Ilft. (lS8:i-"H4). S. ITm-KU. *Miiii/.or, Vj., imd II. \Vi(>nor. Beitrairc zur Anatoniie ii. Pliysiolofiic des CentraliuTvciisysti'ms. Krste Mittli. rdicr dii> Aiissr'lialtunn; dos Iji'iidcii- niarkgrau. Arch. f. exper. Palli. ii. Pliariiiuiu)!., Lim|iz., Hd. xxxv (18!).')). S, 113. !! f Ji 400 TlIK NKUVOUS SYSTKM. nU)n Fifi. miO.— Cross sci'tioiis llircm;;li llif siiiiial curd of a nilihit eleven i';;i'iirrati'il liliirs iViiin I he ilnisil I'liiiiriili art' miii aniniiij till' Uliiii' arriiatii' iiilrriiu'. Kid. 'M)'^. — Cross srrliiiii llirimf;li llii' iiiiiliilla nlili'iiKala at tlii' Icvi'l of tlic lnwrr hair of tlir liililriis olivaris iiil'iTior I'loiii Iho saiiic rase as llic iiri'iiiliiif^ Mkimi'. 11. (iowci's' iinnillt'. {Alter A. Iloclic, Arch. f. I'sychiat. u. Ncivi'iiU'-., Hcrl.. (ill. xxviii. ISSHl, Taf. ix, Via. T). i fibres coiniiiii; froni I he area representiiiii the uppernio.st end of the nucleii.s fascii-uli cimeati can bo seen rdrinini; two btinds, one liirninij: dorsal, the other ventral to the substantia iielali- nosa and Iraetus s])inalis nervi triijeniini to enter the corpus restifornie throuiih which the cerebelluiii is reai'hed.* •Tills path Id llin c'crclii'lliim ai)|iari'iii ly i'i>rrcs( 1 1 i lit !■ rst ni iiiihlf i II li i niliiih II . Xllllls III V Krillikcr' (liicci 111 the CCI' •clll'llllll The iiiiiTiisscil palli from the ilor.sal fmiiculi ilcsitjiiateil liy stiiiie of tlit> (ienmiii wrilers ii diiriii's inii/i'/,irii:fi's //iiifiTsfr(iiii//tli'iii/iirii!<;/sfi'iii. In IS!*;! ||ii;jli T. I'al- rick. of Cliieau'ii (I'elier aiifsteiu;eii(le Deijencraliiiii ii.ieii totiiler (^tuelselniiii; dcs l{iiekeiiiiiarlves. .\reli. f. i'syeliiat. ii. N'crveakr.. Ivrl.. IM. xxv (ISiC!). S. ^i;{l-SM). tlescrilied nlropiiy of lilires in the dorsal paM of ll,e corpus resti- foriiie folliiwiiiir upon transverse lesion al .iiinelion of tl';- pars cerviciilis willi the pars llioracalis of the spinal eonl. hilircs from the fasciculus trra- eilis to the l.-'eral part of the curpiis restiforme were fiiuiid liy Marchi's inothoil to lie (lei^^eneraleil in a case of coinprcssioii of (ho cainla equina liy A. Souipies mill (i. Mar slructiiin jiar compressio SCO (Di'itciu'ral ion asciMnlante ile la moelle ; ile lent c lie la iiueilc i Ic d levul el llu cone lermiua (;|{()UIMN(i ANIt CIIAININO T()(iKTIIKI{ OF N KlUONKS. 4(;;5 Tlic study of Wcij^crl ])n'puniti()iis in l(»iiixitii(liiiiil iiml tfilllSVCl'SC SCCtillll IlilS slldWll llic cxistt'Mi'c of iiiMiiy liiiiitllcs ol" iiit'tliilliitt'd iicrvo lild't's I'Xli'iulin^j Ix'twccii tlic wliitc iiiiiltcr ol' till' (lorsiil rmiiciili iiiid the jxniy lUiittcr ol' the cord. Wlicii llicst' were lirst observed llicy were Itclicvcd to Ix* iiicdullatt'd iilnvrt liaviii;:; their (>riij;in in cells of the cord, and passing i'roiii it into the dorsal white fimiculi. Miit after the study of second- ary deijeiicral ions which i)rovcd that the niaioritv of the white fihres of the dorsal fascicidi are in reality continuations of dor- sal root lii)res, the belief becaiiie current that the niedullaled fibres now uniler consideration represent mainly the terminals of the dorsal rottt tibres themselves, rnnnin^MU to end in the {jriiy matter of the spinal cord. Kxhaustive and exact descrip- tions of these medulhited libres wen' jjjiven by various invesli- fiators who studied Weij^ert specinu'ns; the course of the bun- dles, their arranj^cment in "i'roups, ami the rflative size of tin; individual liundlcs have been known for a lonj,' time. Kven inon^ had been made out. (ierlacli, for example, had mentioned the entrance of bundles of tibres from the dorsal funiculi into the ventr.'d horns,an observation which was coidiruu'd by W aldeyer, I'Mechsiir, and others. \'on Krdliker described t he termination of manv til)res fi'om the dorsal funiculi in the nucleus dorsalis (Clarke's ffray column), iiiid von Lenhossck had called attention to the relation of the dorsal root iibres to the dorsal white com- missure. .\s we shall see, these descriptions, so far as they were ])urely object ive, still have their value. They contain, however. I'rcssf tiuMJ.. I'lM-. (IS!I.")), |>ii. T.V-TH. Sec also t he iiilcri'sl iiij.r cfisc icconlcil hy F. V. Soldor. Xcun.l. CcmI nill>l., I-fip/.., !{«). F,(liii-:cr as early as ISHo (/iir Kciiiilnis ili's Vcrlaiif's dcr IliiilcrsI raii,i,'l'ascni in dvi- Mi'iliilia lllllonl,^•lla iiiid im imtcrcii Klciiihiriiscln'iikcl. Nciinil ('ciilrallpl.. bfi|./.. 15(1. iii (ISS.-)). S. r:i-7()) liiid slated tliai a few lil)res pass dire<'t ly from Ihe fascieidiis f,'racilis an. mid the peripiiery of the cord as lilira- areiiata- externa' dorsales to enter llie corpus restiforrne. The direct tenidnalion of axoiiesof dorsal root lil.res in the cenlielhini .'f the same side s.'ems to he hetter estnhlislied for man tiiaii for animals. The stndy of I'Xperinwntal depMieralions l)y Marclii's method in animals liy such carefnl oliservers as SluMTin!,'ton ami Mot I failed to revi'al lilaek(Mied liliivs beyond the nuclei in the ini'didla. (See Sherrinu'lon. ('. S. Note on the Spinal Portion of some. .Vscendini; Dci^eiicrat ions. .1. I'hysiol., ('aml>rid,e:e, vol. xiv (IH!»;!). pp. 'Jrir>- '.Wi; and Moll. !■'. W. Fxpcrimental Impiiry upon the AITcrent Tracts of the Central Nervous System of the Monkey, itrain, lioml.. vol. xviii (IS!!")). I.p. 1-20.) t' S( 464 THE XEHVOUS SYSTEM. where objootivity was neglected, msiny gnive errors which hud to be corrected by means of stndies made after the metliod of (iolgi. In tlie liglit of the newer results, however, these older descriptions are by no means devoid of value. They can now be correctly interpreted, and indeed a combiiuition of the results of studies by (Jolgi's method with those belonging to the older techni(|ue alone p<. rmit us to understand satisfactorily the anatomical relations of th's portion of the spimil cord. !■ ' ('IIArTKR XXXIV. ( KNTTIIAL AXONKS OK I'KRIPII KKA L CKXTKIPKTAL NKl'RONRS. {(.'ontunitf/.) The (lorsiil root fihros as studied by Golgi's inol luul — Y-sh(i[)od bifu rent ion — Ascending limbs tind descending limbs — Collaterals and terminals. XowiiKUK, porh.'iTts, ill the iutvoiis system lias tlie applicu- tion of Golgi's nic lu'eii of groiiter service tlian in the study of tlie spinal eoru elf. (iolr Ic inal. uei'v., MiliiMo. vol. xviii (IH81), pp. 1 "),■)- Ki,"). t Kiunon y Cnjal, S. ('ontribiK'ioii al estiidio <](> la estruclura de la mi'diila (■si)inal. i{uv. trimest. do liistol. (IHSi)). No. ;i y 4. X von K()!liUiM\ A. reborden feineren Maudes IJiickeiunarks Sitzungsb. d. phys.-med. (iesellscli. zu Wiirzb.. IHflO. S. 44-56. * vail Geliiicliten. A. La moclle epiniero ct Ic cervelet. Cellule, Lierrc ct i.ouvaiii (1H<)1). II von Lerdiossok. M. Op. rif. ^ Ketzius. C. Biol, rntersucli.. Stoi'kliolm, n. F. (18!)1 and IH!):?). l*elaez. P. L. Analoniia normal de la medula espinal liumana y algunas indieiieiones de anatomia comparada sobrc el ndsmo organo. Madrid (18!)?), 569 pp., 12mo. ;}1 465 V i I m 466 TFIK NERVOUS SYSTHM, (2) Tlio dorsal root fibre luis been sliown to divide by Y- sbiipcd (livisio!i soon after entrance into the cord into an ascendiiifj and a desc('n(linre the axones are seen to be grou])ed into two more or less definite portions, a lat- eral group of delicate axones and a medial grou]) of much coarser axones. \ ery soon after entrance each fibre divides by means * Tlie f( \v ('('iitririifrnl fibres of dorsal roots iiicl witli in nuiny iinitnnls fdrin an I'XL'pption to this rule. They have their orij^in in cells in the coril. GR()UlMN(i AM) CHAINING TO(}KTIIKI{ OF NKL'RONKS. 4(;7 of ii forklikc, Y-sliapcd division ut an aii<,de between loO' and 1(!()° into two divisions, an ascending' and a descendins of liifnrcation. l'"roin the stem tilirc. n, a collateral, c. is seen to arise. A number of collaterals arising from tlie limbs of bifnrf the two lini])s. Studies with tiie jnethod of vital staining uith methylene blue have tau^^ht Uainoii y Cajal that as a rule the two lind)s arc of equal thi(dvness, but that in from ten to fil'tiu'ii per cent, of the fibres the size differs essen- tially, and then, as a rule, it is tiie descending lindj that is the finer. As rejifards the course of the ascending and descending limbs after division, this ditt'ers according as a fibre l)elongs to the lateral bundle or to the medial bundle, and indeed varies for the fibres of the same bundle. The ascending lind) of a lateral fibri' runs upward in tlie marginal /one of Lissauer for a greater or less distance. All tlu? fibres in Lissauer's fasciculus are, however, relatively short. Some of the fibres, as mentioned above, run upward in the white matter of the dorsal hoi-n. The descending lind) of the lateral fibre runs oidy a short dis- tance below the point of bifurcation before terminating in the gray matter. The ascending limb of a fibre of the medial bundU^ runs u])- ward in the cuneate fasciculus of Burdach ; it may be short, running in to terminate soon in the gray matter; or it tnay be longer, passing up many segments of the cord before terminat- ing ; again, it nuiy, if it form one of the longest fibres, reach even the medulla oblongata to termimite in the nuclei of the dorsal funiculi situated there (Fig. ^504); or it may even go past these nuclei without stop])ing to enter the cerebellum by way of the corpus restiforme. rnfortunately, thus far it has been impossible to follow in sections prepared by Colgi's method a given fil)re for a distance of more than a few segments of the cord, but in view of the comhijied results obtained with (iolgi's method and from secondary degeneration this statement nnist be held to be correct. The termimitionof the fibres has been studied very carefully. They bend in at various levels at right angles to enter the sub- stantia gelatinosa beyond which they divide into a nund)cr of !'« (JUOUIMNG AND CHAINING TOOETIIKIl OF NKUUONF':s. 4f;y A'. Impuyliismis. XucU'UK funiculi mnriiti. \^ Xucteun /unicnli i/nicilis. ' \k Kadi.r clarsnlis with ijanyliuH ajiinale. ■ Dirii.istltio hmiiixcurnm. Fl(i. 301. — Scliciiic iiulicatiiiK the ciiursc fiillDWcd l)v tlic ci'iitrul iixoiics nf tlic lu'iiplH'tiil spinal ('(')itri|>('tMl lU'iinniis in tlic dorsal I'uniciili cil' tlic spinal conl. (Alter A. van ( ichnclilcn. AnatDniif dii syslc'nic n( rvtnx dc I'lKPninic, a. ('<1.. Lonv., lHi)7, p. '.W.i. Via. ~"*'- • <>" the Icl't side of tlic tiKiiri' arc sliown slKirttT and longer axoncs of a single dorsal root : on tlic rinlit side the rcla- tivc positions of tlu' liniii tilircs I'roni a whole series of dorsil roots («, h, v, i)(). Rev. do cliri., ti-rap. y farm., .Maib'id. t. x (1H!)0-"!)T). jip. .1-8; also. HI aziil dc iiu'li- liMio t'li los ceiilro.s ncrviosos. Rev. triiiu'st. niicrog., INhidrid, vol. i, pp. 1.51-20:5. i. GROriMiNU AND CHAINING T()(JI<:TIIHil Ol'^ NHUUONES. 471 never heeii iible to discover ('olljitcriils foiniiisi olT from the fil)re8 e.m.stitiitin^' the faseieiiliis jfnicilis.* 'I'his iiieiiiiality of ditVer- I'lc. no."). — Cross section throii^'li llic si)iii:il cord of n iicwl)ori> hnlic, to show the collatciiils. lAI'IcrS. liaiiion y (';t.iiil, Arcli. f. Aiiiil. ii. I'liysiol., Aiiiil. Abtli., ISOIJ, S. :«S, Via. 3.) .1. siiicus' vcnlnilis; />'. |h ricclliiliir luiinclics of llic colliitcriils (Voiu the vciilnil I'liniciiliis ; ('. <'oll:itcnils oC tlic vciiti'iil com- inissiii'c; />, ilorsal luiiidlc of Ilic dorsiil coiiimissiirc : /•', middle Imndlc of tlic dorsal coiiiiinssmi' ; /•'. vcnl rai liiiiidlc ol' I lie dorsal coiiiniissiirc ; '1', liliril Imndlcs of llic dorsal riiniciihis wliicli arise iVoiii ils simiinil : //. seiisori- iliotoror rellex collaterals; /, Waldeyer's "mudeils" of the dorsal liorii ; ./, iiiicU'ils (lorsiilis (iarkii receivilif; a distinct Kronp of collaterals. ent portions of tlie llhre as re<^ar(ls tlie oriinj: of the col- laterals ill aiiiiiiiils shows sonic minor dilTerciiees from thos(» found in liuniaii specimens. According to von Lenhossek, wiioso A ^mm = K<>(l. B — TT HIack. E .. - Uroxvii. f -. = (ircfii. Fl(!. 3<)(>. Schiinc lit' tl>'' stnictui'c iif tlic s)iiiiiil ('(Hil ; nerve cells shown in the left liiili'dt' tlieciirtl; eollaterals sIkpwu in the rifilit liiilt' of tlieecml. (After M. von !,enli(issek. Der feineri' i'>au lies Ni rvcns.vslenis, <'te., !.'. Anil., lierl., ISit,"), Till', vi. I i,eft half cif the curd, hlack cells are nintiir; siile tilirils are seen arising frimi their axuiies: red cells are tantonierie nennmes. theaxones fioins; t(p the venlral ami lateral fnniciili. .\niiin}r these are the ci'lls in the nnclelis ilorsalis and sunie <'ells in the suhstantia Kelatinnsi of l>olani;ilis ; li.r., radix ventralis; A'. "s .sid)stiiiu-(> (not iiiciiidin;;' tlios(> wliicli nw most nit'dialiy placed and wliicli are rellex collateralsi. These {jive rise in tlie <;ray inatler to tliat fine complex of delicatti meduUuted llbres known in tlu' hihli- o^n-apliy as '"Waldeyer's inielens of the dorsal horn." Tlie}- prohahly stand in conduction iclation to the small nerve cells silu- jited there. ih) Collaterals ai'isin<,'' from the fasciculus cuneatus medial to Kolandos suhstance from the same area which {j^i ves rise to the rellex collaterals (ride hifrd), althouj,'-h much less numerous than these. They turn transversely hiterahvard to ternunate in <'nd-arhoriza- tions amoni- gert .sections pa.ssin;i: in from the cimeate fasciculus of i^urdach partly v«Miti'o-medial to tlM' substance of Kolando. ])artly through the medial half of this sub.stance, foi-ming S-shaped curves in the gray substance and passing ventralward directly into the ventral horns {Al>scfni ii rii ii()sl)ii ndcf of Scdiwalbe, Bo(/fiibi'ni(lfl of ]{ed- lieh). These bundles are largest in the intumescentije of the cervical and lund>ar regions. They arise always in the si(d;'s riirdt're Wurzelzone ; von Lenhossek's KiiiiitrahluntjHZO)ie or Rvflnxkollaceraleuz" 11 e. %'\ -ii V iiff-' ■i , i 474 TIIH NKllVors SYSTKM. coiisistitiif of a muhiImt <»1' IhiimIIcs less closrly arrniiyrd wliicli iiriso iicaivr tli<> point of ciilraiici- of tlir doi'sal roots into tlit' coi-tl in ||a^ lateral ri'vrion of tlir fasciculus ciincatUN dorsal to ItolatitloM sult- stanct'. Tlicy liavc to pciiclralr tlic snhslanlia ^clatiiiosa l)(>foi'(> uniting with tlic main ir>'<»i|> ventral to tliis sulistanee. All tliese collaterals {Ri'jlr.fliolldtcndi'ii of von KolliUer, Miiiiojo sciisifirih innfrr of Kaiiion y C'ajal) spread out into the vi>ntral horn, calyx fashion, and exhaust thenisel^'es hy nMilti])le division in ainoii;,'' tiie cell hodies, dendrites, auil side lil>rils of tlie lower motor neurones. < )n their way forwai'd they {five oil' side twiys which eoiiie in con- tact with cells of the dorsal horns. The curious hehavior of theso collaterals in the mouse and rahhit where the contact rela'ionsare maiidy willi the side lihrils of ventral horn cells luiH been referred to above (Section V). iiethe's •" fundamental experiment'" (.see pa<,'e 27'J) is also interesting in this coiiiiection. Colhttevah v)i(Jiiit) in flic XiicIchh Dorsith'n (Cliirkii. Stillin- (//). — This vei'v im|)ortant yroup of collaterals has its origin exchi sively in the middle area of the fa.sciculus cuiu'atis, never from the fasciculus {jfracilis. The dark color of Clarke's inudeus in Wei divisions baskets about the indivitlual cells of the nu(deus, eacdi lil)i'e comins,' into contact with the bodies and dendrites of sevei-al cells. In be- {finninjf tabes, specimens stained by Weijjcrt's juethod often show that tlies«' lino feltworks of medullaled collaterals in the nucleus doi'saiis a-e, along with Lissauer's nwirginal zone, the first elements to disappear. ColUitcmh t/oinr/ into flic Dorsal C<)))imiss)()'r of the Siiinal Cord. — The dorsal commissure in most animals is made up mainly of sensory collaterals. \'on rienho.s.sek states that in human beinlicriil Nciisory iiciii'onu is nccuimlcd I'di-. tlHTcI'mt', hy tlic sciisorv cfillittcrals foriniiiy; the (lorsiil <'t)miiiissiii'c. Tliat siicli a I'ccMc mass of lil>rcs can accomil. for tlic sensory (It'ciissatioiis ol" die pliysioloyists no one can su|»- j(osc. Tliis scnsoi'y dcciissalion must nnicli rallicr lie explained, tlierefore. l)y the assumption ol' crossing,'' of the axones of centripetal ueurones of the second older or of hi<^her orders (ride iiifiui). As to llie actual Ivnniiidls iif lliv ii.nnirs of the dorsal root filires, they heiuivc just us do the coliutenils runuiiij^ in to eml in the dilTereiit portions of tiu' ^'niy mutter of the cord and nu'duUa. There is an important ^'ap in our kuowledj,'e in one particular. \\ f (h) not certainly know as yi't whether or imt the terminals of lilires of diil'ercnt lenj^^h have spccitic, thut is to suy non-homologous, end stutions. Should the utlirnuitive ho proved, the imi)ortunce of such u fact for physi()lo(' number of divisions impi'essions from the lower extremity, perhu])s even from the sole of the f sensory passinj; tliroiinh llic vciiti'al coni- iiiissuiv; Init v. Lt'idiossrk iltMiics llic cxislcnce of any such fibres, and V. Kiiilikcr agrocs with him. t Possibly even in the cortex of tlio forebelluai. m 1 i.l. (I iT<; TlIK NK1{ vol's SVS'I'KM. oil' t>n its \V!iy very iiiiiiiy i'ollMtcnils to very (lilTcrciit sc^iiiciils (if tlic cord, wf set' iit :i jj;Iuiici' the iiijirvclloiis dislriltiilioii (if wliicli ill) inilividiiiil cell is ciipiililc. It isdoulttl'id it' Miiywiici'c else in tlic :iiiiiiiMl kiiij^doiii a ^'rcatcr cxtciisioii or a niorc iiiaiiil'old coiitad rclutioiiship is met willi in any cell. I'.acli spinal ncnroiii' may l»c lliou of llic |ii'i'i|ili('nil ('('iili-i|ii'liil ('(iiiiiuclioii |iiillis. 'I'liu ctTuils wliicli iiiivc foiisliiiillv lii'i'ii iiiiiilf le si'|i(iriilf ('('111 ri|n'liil fruiii ct'ii- tiiliipil pallis liavc nearly always jjoiif too far. ('eiilri|ielal aiai < eiil riliipil piiilis roriii pai'ls lit' units (if wliicli the ceiilripeltil path is one liiiil), wliile liie (•iMitrifiif:;!il path is the nther. .Vs far as present kinnvleilp' warrants, (his relation holds pxiii not only for the lowest ceiitres, Inil also, thoiif^h in more eoiiiiilex form, (hroii^'hoiil Mie whole nervous system. ,1 ■■*;'' CIIAITKI} WW. I'llltll'IIKltAI, Cl'.ltllllliAl, CKNTIMI'D'I'AI, N IOC IM»N I'.S COLl.KC 'Tl NO ItOhlLY IMI'KKSSIONS. 'PIkisc iicrtiiiiiiiii^ lo llic iicrviis viij^iis iiiiil iicrviis f,'Iiissn|)liarvnp'us — TIidsc pelt a ill in;; In I lie ncrviis vcslilniii 'I'lmsc iicrliiiniiii; In I lie tier v us iiilrr- in<>iliiis — 'I'liosc pi'iliiiiiiiiLC 111 till' iiiTviis I ri;,'riMiiiiis. 2. Centripetal Neurones of the First Order (ooUooting Bodily ImpresBious) con- neoted with the Rhombencephalon, Till', pcripluTiil ('('111 i'i|M'tiil 4). The central j)r(>lc)nl)ral nerves; head of a hiiniun embryo 10 mm. h)iif;. ( After W. His, from Kollmaiin's text-hook. ) the motor fibres of these nerves, just making their exit, at the dorso-lateral sidens (sulcus lateralis dorsalis). The sensory root fibres of these nerves do not all enter at one spot in a compact mass, but make a number of small biuidles which pass into the central system at several points along the sulcus ( Figs. 35J() aiul \VZ\). In the new-born child the linear extent of entrance meas- ures about .0 cm. (Fig. WZ^t). The medullated fibres plunge through the tractus spinalis nervi trigemini and the adjacent sub- stantia gelatinosa, going obli(juely in the dorso-medial direction j; (IROUIMNfi AND CHAINING TOGETHER OP NEURONES. 479 toward the iiucUm of reception (nucleus ali« cinerea^ and nucleus tractus solitarii) of these nerves near the floor of the fourth ven- tricle. There is no bifurcation of the sensory fibres immediately VUi. 308.- Transv .c section tliniiij;li medulla oblniiffata of newborn eliild at level of (lecussitio leniniseormn. iSeries ii, section No. 5(1.) r.c, ciniiilis centralis; IhcL, (li'cus.satio ieinniscoruni ; /•".«. i., tibrie arcuata' interna'; F.a.c, tiline arcuata' externa' ; /•'.(•., f.isciculiis I'uneatus Hurdaclii ; /■'.(■. to F.r., bundles from fasciculus cuneatus to forniatio reticularis ; F.cls., fascic- ulus cerebellosiiinalis or direct cerebellar tract; /•'.(/., fasciculus Kracilis (Join ; F.r.jt., fasciculus ventralis ])roi)rius ; Xii.i-din., nucleus coiuinissuralis ; S'li.f.f., nucleus funiculi cuneati et gracilis ; A'»./.(;.. nucleus funiculi gracilis ; I'll-. I>.vraniis; T.n.ii.W, tractus spinalis N. trifjeniini ; N.;;.. substantia kcIh- tinosii [Uolandi]. (WelKort-Pal preparation by Dr. .bdin llewetson.) Nii.ac. F.l.ttl Nii.oQ.in Nu.Q. Fid. liOit. Transverse section of medulla oblongata of newborn child passing (hroUHli (he lUK'leiisolivaris inl'erior. iSeries ii. .section No. 10;i. ) ('.)■., corpus restiforme: l\ii.c.. libra' arcuata' interna' from the anterior half of the nucleus I'uniculi cuneati : F.l.m.. fasciculus lonj;itudinalis medialis ; .V./.V..V., N. j;los.sopbar,vuK<'Us et vafius; \..\ll., N. h.vpojjlossus : \ii.ii.. nucleus arciiatus; yit.n.r.. nucleus abe cinerea'; Xii.f.r., inu'leiis funiculi cutu-ali ; \ii.t).ii.iii., nucleus olivaris accessorius medialis: A'imi./'.. nucleus olivaris inferior: S'li.u.Xll.. nu 'leus N. b.vpofiiossi : /'//.. p.vramis ( uou-medullated) ; N.r/.. substantia Kelaliuosa Kolandi : st.i.l,, stratum interolivare leninisci : T. n., tractus solitarius : 'r.s.)i.\'.. tractus spinalis N. triHcmini: I'.i^., ventriculus (piartus. I Weisert-l'al preparation b.v Dr. .Iidin llewetson. ) after entrance, a fact wliich is not surprisinjif when the histoge- netic relations discussed in Section IV are recalled. The bifurca- ,, I t' 3 1 1! ; ■i i 4S0 TIIK NKItVors S VST MM. 1J(»M oi'ciirs just \vli('r(> one would ft /iriari r\\nH-\\\ to take pljuu', iiaiucly, when [ho lilircs liavc rcacliftl (lie iici/j^liliorliood of tlieir gray luicici of tiTiiiiiiatioii near tlu' lloorofllic ventricle. In real- ity. lluMi, the analogy with the behavior of the dorsal root libres of the spinal cord is nearer than if the hifureation occurred ininie- itxii a<.i\ Num. Vtioim. Flo. ;U0. — TninsviTsc section of nitMliillu ohlon^Mta jiiid crvclirllimi of nrwlioni I'liiiil. (Scries ii, seelioii No. 1 l(i. i ('./•.. eor|Hls rcslil'oniic (llicpiiil iiumIiiI hilcil corrcs|ioiiils in llie nniiii to llw dircrl cevclH'lliir trad): /■'./., Imndlc Illicit iirii^,^|'iT|i«t.-« III till iiiiilll \ y ' 111^ iiiiii\ iiii>>«itiii _-..-.. _.-_, .,. coiUiiiuous u illi the riiiiiiiiliis lateralis of the cord : l-'.l.iii., Casciciiliis loUKi tiidiiialis iiieiiialis : .V./.V..V.. N. Klossopliarviificiis d vakils; .V,.\7/.. N. Iiypo- ^lossiis: \ii.il.. imcleiis 7.i./., stratum inleidlivaic leuiiiisci : '.v;, plane of loUKitiulinal seelion No. (ili. [NoTK. — 'this liyure has lieen disproporlionatel.v ii'duced in the reprodui - tion.l I \Vei^;erl-l'al pi'epaiat ion li.v l>r. ,l. cit.. nd. ii. S, ','40. \ Held. II. I>ie JMidi^unuswiMst' der sensihleii Xerveii ini (n-liini, Ai'cli. f. .\iiat. u. Physiol., .\iiiit. .Milh.. I-eipz. (I8!»0). S. ;t;i-:!!l. J Uaiiiiui y Ciijid. S. ItcilrMi;' /ur Sludinni der Medulla Olilmiifata, etc. Doiitsehe r(d)ersel/.. v. Hresler, Leipzig (,lM!l(i), ,S. 4:5. (illOUlMNC. AND CIIAININU TOdHTllKK oF NKUUUNES. 4Sl ' : r I- = s t S.-S r = J-b - . >" • 3 v^' t; s s ■ z ■ "^ •^, I. s *-, z ■■ .^1. . . t .•~ •= — C2C -; i.i IS'^ 2.> *•-; = i X 2i = r?-~^-|^.^'::^:.'i3-2 ■ I: = •= r = ^ -r - = « ~ = ■-: 2 ;:- 3"-.=,'^ s~- -J 7. = =- - 32 Uf ; i 1 1 . ,!„;•,. ,1!. 482 THK NKKVOUS SYSTEM. k >7 < ^ ^' fc. V w B - ^ 13 d *^ = ;::[;§« — .- -^ £3 n *-> ■r ..s . £^^> a o c . . S X w 4. . ~- ^'"S.' J=i - y £ - . . £ , r .. c c ^■^,= 2 rt — ic "3 i; £ ■•" .S 2 c ^ :i ...2.J .,., — ■/: ^ •— X = .,■ :- C S • ^'^ t^ - — . « ^ a S 3 u ^■1^'r.>-. .It. 15-'. .. rt ? = ^ = *: = = ^ X " 2 = 5. r li c ciS K'Z K.~ o OROUPINd AND CIIAININU TOUF/rilEU OK NELRUNKS. 483 ^ 7. p i est; 5t 5: 'E.'- = -rs a'- t:.:i 5 i-=-^ - < = c 3 3 i := b r g; . §i '5 ' . . ~. •- — 3 .H K ''' ^ -S B •• „ = = y. i E"- i O \ 1' 1. t :* ;•<((;>• •■<>] iklll 484 TllK NKinOl'S SYSTKM. !il;»' cincrca' dixiilc in tlic Itimdlcs nciir tliis init'lciis, tlic rest of I he lilircs inside it. 'Vhv lihrcs i-nicrinj; I he Iraclus soiilarius undergo division, l)ut not all at tliu sanu' level. Vw. :n 1. TrMiisviMso st'ction tlirDU^Ii islliiniis rhoinlicixM'iihali ol' iicwlxini Uiilir. \V('i};rii-l';il, scries ii, Mclioii Nn. '^'liS, ) /I'c.coi, , liriirliinin ruii- .imicliviim ; ''.('.. rolliciilus iiilcrinr ; y, iiinli'Us (U'sciiliiil l).v Wcsliiliiil as luiilialily ciinrctiird ill I lie iiiiniii iil' ilic N. t iiiclili'iirls : /'./.mi., rasficiilus loimiluiliiialis iiicilialis; /•'./'//., rasciiii I i li)iiyituiliiialt's [iiyiaiiiidalt'sl : /../., IciiiiiiMiis lalinilis : l..m., Iciiitiiscus mcilialis; .V. / 1'., ilrciissilio iH'rvuriiiii Iviiililcariiiiii ; .V. I'., N. Iri^'i'iiiiiiiis; Sii.l.l.. iiiirlciis Icniiiisci lateralis; .V". /■./.. iiiu-leiis relieiiljivis leuiiieiili pniilis ; It'.il. 1".. radix deseeiidens [iiiesell- eeplialiia] iietvi tiiueiiiiiii. I'l't'iiaraticni liy Dr. .Iiiliii llewelson. ^ The tignre copied from Held (l"'iir. 'VH<) shows root fibres dividing, ont' branch passing to the nucleus ahv ciiuM'ea', the other descending in the tractus solitarins. These descending fibres give otT collaterals (I"'ig. :{t?T) and torniinals, to end in the adjacent gray matter (nucleus tractus solitarii). Kainun y ("ajal denies the existence of typical bifurcations (at least for the majority of i . fibn^s of X. 1 .\ and N. X), and thinks that * Wost pluil, 0. Ueber ciiicn Fall von ohroiiisolier iirofjrossiver Jjiilimiiiii,' d(>r .ViiireniiiuskelinOplitlialniojilej^ia externa) iielist l?eselinMlimiji von (ian- glieM/elloniinippen im Ho 'ho iles Oeiiloiiiotoriuskenis. Arch. f. I'syi'liiat. un.l Nerveiikr., Herl.. H.l. xviii (18H7), S. yW. » »U., (il{(»ri'IN(l AND CIIAIMNd TOOKTII KU OK NKIMIONKS. 4^5 t licsc (ihrcs, tlisolx'viiif; t lie ^fciicnil law ol' diclidt oiiiy, iirf i. lilni's iiiiiiiini; IVdiii hileiMl leiiinisriis lowiird li|iei'iiir iiiiilei III" I lie vesi ilniliir nerves nl' tlie (wii sides ; /•'././».. riiscienlils lon- jiiliiclin;ilis inediiilis : /•'. /'//.. riiseicnli liiiit;iln(liiiiiles pniilis i iiyniniidiilesi ; I,. I.. leinnisens lnler:ilis in Imi'^i' |i:irt leiiniiKililiK in llie niieleiis i>l' (lie eollirnlns inl'erinr; /,.«/.. leinnisens iiiediiilis: .V./l.. \. I nielileiiris ; .V//.r((//.n//',. nneleiis ; rineseiiee|ili;iliiii] N, lriy;eniini ; S/.m-.r.. slriilnni i-riseiini c ciil rule. ' I'repiini- liini li.V l>l'. .lolili llewetsnli. i ])assa{;e spinalwanl it i,fradiially approacdies the median liti", lyiuj^ in its lower part medial to the nucleus funiculi gracilis. Its fibres f m ; I i 1? J / 'i t' '!!!■! 48«; TIIK NKKVOUS SYSTEM. '' 1 % \^ f can he seen tcM'iuiimtiii^j iit tlilTcroiit li'vcls in the nuck'iis tractus solitarii wliicli lUM'oinpimic.s it. The f?niy mutter of this mielejis iiion^ or IcHH .surrounds the tract, l)einc(ni IkiIm'. I.cvcI 1)1' ccilliciili suiMTiiins III' (oriMiiii (|iiii(liif;(iiiiiiii. ( WciKcit-I'iil, .'^(^i(•^^ ii. sec- lion .Nil. H15S. ) . I(/. (■(■)•., ii(|ii(./.. (Ictiissiitiii Icnincnti vintiali.s {rcKlrnli' llitiihn(hii-irjiiiiii oi l'"ipiil ) ; F.I. III.. I'iisiiculiis l(tii;;itii(liiiiilis iiicdiiilis ; /•'. /'//., fasciculi |>.vi'aiiiiilalcs ill the pars l)asilaiis pimlis : /,./«.. Iiniiiisciis iiicdialis ; .V. /I'., N. tniclilcaris ; S11.I..1.. nucleus lateralis supi^rior ipf I'^leclisi^' ; Sii.ii.lV.. nucleus N. tnicli- lcaris; Sl.iilh.ji., stratiiiii alliiiiii pi.^, decnssatio tef,'nicnli dorsalis 1 finifiiiiiinrtiiir Iliiiilinilirir.111111 i>( Meynen): I\l.m.. liiscicnlus lon}jitii;i"isi'Um cenlrale: .s'.»., substantia ni^ra ; a, rej;ion of Kleclisiji's Fii.s.sschleife ; P. temporo-occipital tivu't to pons; 7, frontal tract from ))allium to i)ons. I Preparation liy Di'. John llewetsou. 1 Outside the central nervous system the nervus vagus forms numerous anastomoses with the sympathetic. The relations are well shown in Fig. 330. il 488 TIIH NHItVorS SYSTK.M. Str.alb.pi iiij;, sciU's 111, sec liitcnilis toward • 0. (Icciissttin (■(plliciiliis '• /•'.(■.. fiisci Fui IMS. Ilitri/iiiital scclinn tliniii;;li tlic iliDiiilpi'iiccplialdii and iiicscncciilialdit ola iu\vl>c>ni halic. ' vcl of imclciis iicrvi alHliiccntis. ' \V<'i^'ci't-ral slain- ti(t. I o, liltrcs riiiiiiinv' tVoiii region of linmiMiis I'acliimii conjiiiictiviiiii ; .(... ./•. iiinlcus fiiiiiciili gracilis: Xii.ii.cil.. imclciis N. coclilca' dor- salis ; .\ii.n. 17., nucleus N. alidilceiilis : Xii.ii.i'.l.. miclciis N. vestilmli lateralis I Deilers i)ars media I is ; Sn.ii.r.l.,. nucleus N. vestilmli lateralis Deiteis pars lateralis: Sii.ii.r.in.. iiucleus N. vestilmli iiiey/-.((/^(./).. si laliiin allium proluiidum : 7'c..v,. tract us solitarius : I'.i/.. ventriciiliis (luartiis. I'repanitinii liy Dr. .lolin ihwetson,) «K<»ri'IN(J AND CIIAININCJ TOOKTIIKH (»K NKl'UoXKS. 4,sj> CoU sup. /l<^.f♦l■. St.alb.p. ■ H,. V .i N.W ^- ■• ^ -DecBecht., Nucl.n.abd. Rad.dPsenvRSt Fasclmed. Corp. rest. .j)^Nu.n cochLd. ■Tr.sol. ■Nuclf.cun, Nucl.n.hijp. -Fa cun. ■NuclUr ■Ya.Pt. Fl(i. 310. Iforizontal soctioii fliniiij.'li tlic rliciiiiliciiccplialnn mid mcscncciiliiilriit tit'a iH'wlHini lialic. WciKcrt-l'iil staiiiiiifi. Level ol' ventral jiart of iiiieleiis iiervi atiiliicciilis. i Series iii. .■^ei'ticiii No. 7^. i .l(/.(cc.. a((ue(lii<'tiis eereliii; Hi-Kili.Ciiiij.. liiacliiiiiii coiijuiutiviiiii : (hlLsiij).. collieiiliis siipericir: < 'oil. inf., folliciiliis inferior; ro/'y/.ro^.. corpus restit'ornie ; l>ii. Itiilil.. tilires of ventral jiortioii of liraeliiiim con.jiinetiviiin forinitif; a connnissure between the supe- rior nuclei of termination of tlie vestibular nerves of tlie twositles; I'li.nin., fasciculus cnneatus: /■'(». i/c. fasciculus Knicilis: F.<(.j.( IV.vM, libra' arcuatic pertainiuf; to llie ciiitnil vestibular pailis: luisv.l.iniiL. fasciculus lonjji- tudinalis nudialis: l.fiiiii.ldt.. b'niniscus lateralis; Mnl.nlil., medulla ob- longata; .Vc.scHc, meseu4'eplialll,.i,, (•ollieiiliis siiix'rior; f '.»•.. corims i'estit'i)niie ; F.ii.i.. libra' arciiata' inteniii' ; F.rlx., t'asciciiliis cerelu'lliispiiialis or diri^ct cereiicUar tract: Ren., laseiculus uli : A'. /.V, .V, radices Xn. {{lossopliaryiifjei et vani ; .V(( ../'.(•»., nucleus funiculi cuneali ; A'»../".f;.. nucleus funiculi firacilis: jV».».c.'/., nucleus X. coelilea- doi-sjilis ; A'».». r., luu'leus \. trij;emini ; .V».)i..V//, nucleus X. liypofilossi ; yii.l.i., nucleus lateralis sujicrior of Fleclisij;; L'.d.ii.irsl., radix descendens N. vestilaili ; Sl.ij.r., stratum };riseum eeuti-ale; Siih,iicl.lii)l(iii<'i, substantia Kelatiuosa Rolandi ; Tr.snl.. tractus solitarius; T.n.n.l', tnictus spinalis X. trifjeniiui. (Preparation by Dr. John llewetson.) "' ~ ' * ' ■ .. t! ■1 ■ C! Fkj. .'521. — Ilori/oiitiil section timing')) tlio iiicdiilla, pons, and nii(l)>i-ain of a now- horn lial)c. \Vcif;crl-I'al stainitiiL;. Lvvv\ of nucleus nervi oeuloinolorii and nucleus nervi lioclilearis. i Series iii. section No. 10(1. i .I7. co'.. a(|Uedlu-tlls cen'hri : /(c. co/i.;.. l)raeliiuni conjiinclivuni ; r./)., eoniniissura posterior cere- lui ; ('. liiclil.. eoniniissure l>et\veen i?eclitere\v"s nuclei of the two sides; r.;-., corpus restifornie : l-'.l.ni.. tasciculus lonKitudiualis niedial's : /'.c. In I'.r.. lihr< s from fasciculus cnneMt us to forniatio reticularis: Fih. d-i: nil.. iWiv.v arcualic interna': /•'. c//.. fasc. cuneatus ; /•'.)■.((.. forniatio reticnlarisalha ; Mat. ('..radix niotorius N. trif;<'niini : .V. 17.. radix N. ahducentis : .V. res/,, radix N. vestih- nli : .V. l7/.i('. '. radix N. facialis, pars seen nda : .\. I.\ miil X. radices Nn. Mlossopharvnirei et va^i : X.XII. radix N. h.vpojilossi : Xii.c.s.> tn >. nucleus centralis superior, pars niedialis: Xii.v.kjI >, nucleus cent I'alis superior, pars lateralis : Xii.l.l.. nucleus leninisci lateralis : Xii.l.s.. nucW'Us lateralis superior ; Xii.ii.lll.. nucleus N. oculoinotorii : Xii.ii.H'.. nucleus N. trmhlearis: /...v., lemniscus superior; Xii.f.ii.. nucleus funiculi ;;raeilis; Xii.ii.r.i-.. nucleus N. cochlea' vent rails : .V».».17/, nucleus X. facialis: S.;/.. snhstantia jrelatiuosa ; Sl.i.l., stratum intemlivare leninisci; Sm.]'., radix sensiu'ius N. trijremiui ; St.il.i:. siratiini uriselini centrale; Suh. iirl., slihslantia ^elatinosa near eii- traiice of seiisor.v part of N. trigeminus: 'I'r.s.n.l.. tiaetus spinalis N. trijjem- ini : 'I'r.fr.iix.ll., ti'act from Deiters' nucleus to the spinal cord. 1 {'reparation h,V Dr. .lohn Ilewetson. 1 •GUUl' •I.ING AND CHAINING TOGETllKU OF Ni:CRONKS. 4<.»1 C.p. -Aq.cer. Fv.. MX. m I 1 i ■-« rM 41>2 TIIK NHItV(»l'S SYSTEM, ^"^■'•^c-ft o Nu.r.t. \ s, m I f l:4-^>v-^ J'-^;, )/Vt:^^:m :;m A*. /■'"; .,■: , ,. y.^|^->^ Sen.Y, H.Y1I N.Yest. •H.YI. IsM IctcEr. Fig. 3^2. IIori/.oiit;il scctioii tlimuKli the incdulln. ixins. and mi(ll)riiin iif a ncw- lioni l)alic. Wcifji'rt-I'al staiiiiiifj. Level dC tleeussiUio liracliii enii.jimctivi ami of nucleus reticularis teffuieuti. (Series iii, seetion N'd. lOH. ) ('.p., eiiinniissura posterior eerehri ; Dfc.H.r., decussitio liraeliii eonjunetivi : Pir.Hrrht, eonnnissure lietweeu l{<'elitere\v's nuclei ; II. t., tilires to decussjilio tefinu'nti ; F.ti.i.' (\ Whnv arcuata' interna' from the nucleus funiculi ciineati : /'. fasciculus cuneatus; F.v. to F.r.. bundle from fasciculus euneatus to forinatio reticularis; F.tj., fasciculus ni'Jieilis; F.l.m., fasciculus loUKiludinalis medialis : /,. lemniscus medialis : /,./.. lemniscus lateralis Milt. v.. nidix motorius \. triKemini ; X.VII., radix N. facialis. i)ai>i secunda : \.n'iit., radix N. vestiliuli ; .V. 17., nidix N. al)ducentis; S.XIl., radix N. liyi)o(;los,si ; .V. .VA,, radix X. . II l.id). nucleus X. ocidoniotorii, pal's lateralis: .Vi/.ii. ///.'/> ), nucleus X'. oculomotorii, ]iarsimi)ar: yn.c.-t.ih nucleus centnilis superior, pars latei-.ilis: .Vk.c.v. micleiis centnilis superior. i)ars medialis : Sii.l.l., nucleus lemnisci lateralis; Nit.u. VII., nucleus X. facialis: Xn.y.c.r., nu<'leus X. cochlea- venlnilis: Sii.r.'i.. nucleus ceii- tr.ilis inferior ; Sn.r.t., nuc-leus reticularis teKineiiti ; .V»./..s'.. nucleus later.ilis superior: St.qr.r., stratum firiseum centrale; Sfii.]'., sens(u\v root of X. trifieminus: N.;;., suhstantia Kelatinosii Kolandi : Tr.fr. iiii. I)., tract froin Pciters' nucle\is to the; spinal cord: T..s.ii.l'., tnictus spinalis N. trif{eniini. ( Preparation hy Dr. John Hewetson. - GKori'lNCJ AXI) CilAININa TOGETlJEll OF NKUHONKS. 403, Fasc.retrof. 494 THE ISEKVOUS SYSTEM. ,Ku.n, nr . Nu. ruber. L.m. a. Yin. Uoct^i H,YI ■Fl, •Fa.iADacl) Fro. :W4. Fid. 324. — Horinontal section tliroii);)) the inodtilla, pons, and niiill>niiii of new born I)alu'. Ijcvcl ot'stnitinn iutcrolivarc Icnmisci, corpus trapc/.oiilt'inn and niulciis nilnT. NVciKcrt-l'al staining, i Scries iii, section No. lUti. i r./., cor- I)us tnipezoideiini ; Dec. llr.Ciiiij.. dcciis.siitio linicliii coii.jiinctivi ; />./., decus- .satio tcffnicnti ventr.ilis (ventral tegmental dccnssiition ofKorel i; F.ii.i.i Dec.l.), tilira' arcuata' interna' (decussatio leniniscoriini) ; /•'./., tilires continiionswitli the fnnicnliis later.iiis of tiie spinal cord; F.l.m., I'asciculiis lon^itudinalis nieilialis; /•'.;•., I/.. I'asciculns retrodexns Meyiierti ; l..iii., lemniscus nicdialis; y.lll.. radix N. oculotnotorii ; S.Mol.l'.. motor root of N. trigeminus; A'.Scii. r.. sensory root of N. trigeminus; .Y. 17//. (coc/i. i. nidi.x X. cochlea' ; .V. 17//. I rest, I, radix X. ve.stihuli ; .V. 17., nidix X. ahducentis ; A'. 17/., radix X. facialis, pars s<'ciin(hi ; .V. A'//., radix X. hypo>;lossi ; Sii.J'.l.m.. nucleus fasciculi lonjiitudinalis medialis. or nucleus commis.4ura' pctsterioris {olierer Oniliimotiiriit.iLmi of Darksehewit.sch ) ; A'». ».///., nucleus X. ocuhmiotorii ; Xn.ti.it.m.. nucleus olivaris accessorius medialis; \ii.i>.i., nucleus olivaris in- ferior; \ii.i>..i., nucleus olivaris superior; .Vd.cKftc;-, nucl"Us rul)er; N7.(.)., stratum interolivare lemuisci ; .S.«., suhstiiutia nigra, i Preparation t)y I)r John llewetsou. > 88 rstt't: Fl(i. :wr). — hiiinriini ]ir<'|(ari'(l ))y Miss !•'. Siibiii t'lcnii a sciifs of s(<'tii)iis tliriiii(;h till' Imiiu III' a iifw-liiini lialir. shiiwiiiK the nuclei uf the ((rclnal mrves ami tlir area iil' exit ami iil' ciitraiii'i' of tlic runts nf llii' ri rclinil m rvis in Hat pru- ji'itiiin. ((. line nl'lali ral fdifc id' fiiiiilli vent rirlc ; il. il. it, il. fitsca inrcrinr; c. I'liVfa snpcriiir; ;;, lateral surl'ai'i' nl' rlinnilicncciilialun ; ///.. area nCixit of N. iicnloiuiitorius : /!'., area of exit of N. Iroclilraiis ; I'., area of exit anil en- IraiiiiofN. triKi'ininiis ; 17., area of exit of N. alxluccns: 17/.. area of exit of .N. farialis; 17//. {ciii'li. i, area of cntnincr of N. coclileii' ; 17//. < rrslih.'i, area of I'Titrancc of \. vcslilmli: /.V. ami A'., area of intrancc of N. ^lossopliaryn- t'eiis et vajius; .\7., area of exit of N. ai eessovilis : .V//., area of exit of N. hypoKlossiis; .Vi(. ».///.. nuileiis X. oculo-niotorii : .Vi/.n./l'., nuilens N. troili- learis; Xii.ii. I'.i »(./(. ), nneleus niotorins jirineeps N. trineinini : Xii.ii. 17., nu- elens X. aliilneentis ; Xii.ii. \'II.. nucleus X. facialis ; Xn.ii.. niiclens aniliinuus : .\ii.ii.r.. nucleus ahecinercie : .\ii.ii.r.m., nucleus X. vest iliuli nicilia lis ; Xii.ii.r..t., nucleus .\. vest iliuli superior; .\'ii.ii.r.l., nucleus X. vestiliuli lateralis i Ueiters': ,V((. «.(•.'.f/.. sulistantia jjelali- no.sa ; 7'. sdI., tractus solitarius ; Tr.s.ii.t.. tractns spinalis X. triKi'inini: I'l'nl.. ventral horn cells. The numbers to the left of the (irawinjr inilicate approxi- niately tile levels of l!ie cnrri'.siHtiidinjr transversii sections represented hy Kif{s. :{US to 317. The plane of the sections from whicli this diagram was made is not (luite trans- verse hut somewhat ohlinne: the dor.sal surface of the medulla lias lieen struck hy the knife more cereliral ward than the ventral surface, the anyle formed hy the plane of the section with the longitudinal axis hein;; ajiproxi- inately seventy decrees, as measured on the cerebral side. This accounts for the evident ' slight i displacement cerebralward of the structures in tlie ven- tral imrtions of the sections as compared with those in the dorsal iiortions. . (iUUUriiNG A.ND LJlAlMiNG TOUETllEK OF NEUKONES. 4 I ! '1! \ I -^ ;ii 4. I'.ndiiiHs III' axiiiu's dl' N, vii«iisiiii(l N. jilossoiiliiir.vimciis, 'I'lic liliics tiiniiim iliiwii iiilii tlir liiicliis Milit;iriiis arc well lowii. (Al'liT II. Ililil. Anil, r. Aiiat. ii. riivsiol.. Anal. Al.lh., I,<'i|i/... isit;.', 'I'Mf. i, l'i«. I.) Fill. !?^'7. — Tiactus siilitiiriiis lit' a six-ilay-iild cat. nt'licalc cultali'ials arc seen I'omini; tVniii llic main axntics. i After II. Held, .Vrcli. t'. Aiiat. ii. riiysinl., .\iiat. .Vlitli.. I.iiii/.. !*. — ( 'ross .scctiidi tliniUKli tlic rhiiinhfiicipluilnii i)f a four-diiy-olil tni>iis<>. lAI'tcrS. Uainoii y ('ajal, licitrun /.mn Stiiilimii dcr Medulla Oliloiifiata, etc., Lfii)/,., 18i(t), S. 48, Kifj. lU.) I, iiiiclciis N. Iiypo^lossi ; /;, miclcus ciiin- inissiiralis ; <', iiiiclciis olivaris inferior ; />, tiactus s])iiiali.s N. triKciniiii ; /■', motor n»)t of N. vafjiis and N. KlossopharynKciis ; F, iniclciis anibiKim.s ; (1. posterior extremity of nucleus N. vestiliuli nidicis descendentis ; //, eross section of tra('tus solitiirius ; /,. lil)res h'UUK to inndeus olivaris inferior; «, pyramis; h, collat<'riils from tlie pynimid and from the substantia allia lateral from it; d. collaterals from tlie fasciculus later.ilis proitrius ; c, sensory col- laterals for the nucleus aml)i}ruus ; /, n^i'urreni liltres in motor roots which run toward tractns spinalis N. triRemini ; ./, crossed motor root lihres of N. va^usand N. Kl<»haryunens ; h. collatenils of th(> sensory root of the N. vaKUs and \. glossoijIiaryuKeus runuiiiK in the fasciculus solitiirius ; i, proto- plitsniic commissure hetween the nuch^i N. hyiioglossi of the two sides. t'l tiK()LI'IN(i AND ClIAiNlNCi TOUKTllEU OK NKL'UONKS. 4Jjlexu». Fio. 330. — Syinpalliii'iis and N. vaRiis of a liuniaii cniliryo vit'wcd from tlif ri(;lit side. lAt'lcrW. His, .liiiiior, and ,1. Kullniann, frinn Kollniann's Lt'lirliucli del- F-iitwickcliiiiKsKcscliiclilc dcs Mcnsclitii, Jena, IHIIH, S. rMl Kin. :{:5ti. I prolongations to the vestibule and seniicircnilar canals, especial- ly to the macula aoustica utriculi and to the cnstse ampuUares of the superior, posterior, and lateral membranous ampullw {V'lg. XVi). These peripheral fibres, after repeated divisioJi, all end free * in an)ong the hair cells situated there, coming only into Qontact relation with these cells (Retzius, f van (Jehuch- 1 ' ^^ I * The observations of II. Avers — A Contribution to the Morpholofjy of the Vertebrate Kar, with a Reeoiisideratioii of its Functions. J. Morphol., Host., vol. vi (18!)2), p|). l-3(iO; Teber das peripherische Verhalten iler (iehiirnerven und den Wert der Ilaarzeilen des Geiiororganes. Anat. .\n/,. .Icna. Wil viii (1892-'0:i). S. 435-440— who formerly, at least, lielieved that aeoustie nerve filires arise directly from the hair cells, is in disagreenicnl with the findings of other investigators. + iJetzius, 0. Die Kndigungsweise des Gehi^'nerven. Biol. I'ntersuch. *Stoekholin, n. F., Bd. iii (1892), S. 29-30. !:-fPrll w^ 500 THE NKKVOUS S VST KM. ten,* Hiimon y Cajiil,t von Lenhosst''k,J and Krause **). Inas- much us the endings in the maciihi acustica sacculi (Fig. ■i'-i-i) correspond closely to those in the macula acustica utriculi, tlu' AVrci/.s riifhltip. Servus vixtihuli. Nervns fdciolis. danijUon vestibulare. (Itiiiijlioii tjenicnU. (ianylion spirale. Systeniii ticn'oniin rvntriilv. JiecfSHUn lubyrinthi. Ductus si'iiikhcultirin IHisterior. Durtiii sfiiiicircuUiiis l{itii(ili>i. I'fricnliis. Sacotlus. — ' - • Diu-tns cochlearis. '•""-■i.iir ri(i. 331.~-Ii('ft iiuditory vesicle with the aciistico-tiiciiil (•(nniilex dCa hiiniaii ciii- liryi) iit the liltii weeli. i After His, Juninr, fniiii K.illinaiiirs text-lieok, S. .>»(), Kifr. ;w:5. > (juestion may naturally be raised as to whether the saccular branch of the nervus cochleic really may not subserve the same functions as we now attribute to the branches of the nervus vestibuli. In tlie latter event it would perhaps be justifiable to remove the neurones corresponding to the nervus saccularis from the group of peripheral auditory neurones, and to in- clude them with the group at present under consideration. The central prolongations of the cells of the ganglion vestibu- lare, united into a compact mass as the nervus vestibuli, enter the central nervous system at the junction of tho medulla and * van (ielmchlcii, A. ('oiitributions i\ Telude des ganglions eerehro- spiiiaiix. Hull. Aead. my. d. se. de Tielp., Tiriix., :{. s., t. xxiv (1K!)2), jip. llT-ir)4. t Rainoii y Cajal, S. El nuevo coneepto de la histologia de lo.s eeiitros nerviosos. IJev. de eieii. med. de linrcel., vf)l. xviii (1802). pp. ofil-;i7(>: and pp. 45T-4T6. I von I>en]iossek, M. Die Xervonendigunfjen in den Maenlu' und Cristie acnstica'. Anat. Hefte, Erste .\htli.: Arh. ans anal. Inslit., Bd. iii, Ileft 0. S. 2:!1. * Krause, H. Die Endi}runf.'sweise des Xerv. Aeiistieus iin Gehiirorgnn. Verhaiidl. d. anat. (Jesellsch.. Jena. M. x (18!)6), S. 105-17:5. (il{OL'lMX(} AM) fllAlNIXd T()(}l>yrHKR OF NEUUUNKS. 1 i , 1 1 the pons as the vestibuhir root of the acoustic ncrvi' (radix vestibularis X, acnstici). Tlic (lenioiistration l)y von Hi'cliterew* in 1SS5 of the existence and anatomical independence of two roots to the nervus a(!usticu8, one (posterior and lateral) connected with the cochlea, tiie other (anterior and medial) connected with the vestibule and semicircular canals, formed the starting point of the series of inves- tif^ations which have gradually solved the uiuch-vexed questions concern- ing the origin aiid central connec- tions of the "acoustic" or eighth nerve. Von Hechterew's researciies fouiul a most important confirmation and extension in the investigations of llis.+ This root enters at a point farther anterior (cerebral ward) than does the cochlear root. It is also situated medial to the cochlear nerve, and after entrance passes obli(|uely, medial to the corpus restiforme (be- tween it and the tractus spinalis nervi trigemini), in a dorsal and me- dial direction towaril the tloor of tiie fourth ventricde. A little lateral from a point midway between the median line of the medulla and the F lateral margin of the corpus resti- fornu' at this level, the root fibres, as von Kolliker and Held have shown, undergo bifurcation, dividing into a coarse descending and a more deli- cate ascending limb. This bifurca- yriiitli of errors into whicii the oldi-r investiga- tors wert' led. Amid the pMieral confusion a reader of the oUier arlich-.-. can not help beinjj impressed with the careful objectivity of the descri;)- tions of tlie j^reat Knjjiish neurologist, J. Loekliarl Clarke (I{esearc''es on the Intimate Structure of the Hrain, Human and Comparative, lull. Tr., Lond., vol. exlviii (1858), pp. ^IJl-'J")!). — Researi'lies on tlie Intimate Structure of the Hrain. ibid., vol. dviii (I8(»H), pp. 2(i;}-;5;il). Tiie pulili- eations of John Dean, of Hoston (The (Jray Substance of the Medulla Ohlonjjata and Trapezium, 4lo, Smithsonian Conli'ihutions to Kno\vled>,'e, \Vashinjj;ton, 1H64), show excellent illustrations of the region in (juestion. The orij,'inal articles of (). F. C. DeittTs (rnlersuchnnf;;en nciier (iehirn uiid Hiickenmark des ^lenschen und der .Sihigethiere, nach dem Todo des Verfassers heransgegeben und bevorwortet von Max Schultzo, 8\-o. Mraunschweig, 186")) should be consulted by any one wishing to under- stand the position taken by this celebrated neurologist concerning the nuclei in ({uestion. + von Hechterew, W. Ueber die innere .\btheilung des StrickkCirpers und den achten Hirnnerven. Neurol. Centralbl.. Leipz., Bd. iv (1885), S. 145-147: [Origin and Course of Stria' medullares s. acustica\| .Aled. Obozr., Mosk., vol. xxxvii (1892), pp. 470-478; also in Xeurol. Centralbl., Leipz., Hd. xi (1892), S. 297-;505.— Der hintere Zweihiigel als Centrum fiir das (Jehur, die Stimme und die Reflexbewegungen. Xeurol. Centralbl., Leipz., Bd. xiv (1895), S. 706-712. X Flechsig. V. Zur Lehre vom centralen Verlauf der Sinnesnerven. Neurol. Centralbl., Leipz., M. v (1886), S. .545-551.— Wcitere .Mittheilungen uber die Heziehungen des unteren Vierln'igels zum llornerven. Neurf)l. Centralbl., Leipz., Bd. ix (1890), .S. 98-l(i(t. * Baginski, B. Ceber den Trsprung und den centralen Verlauf des Nervus acuslicus des Kaninchcns. .\rch. f. path. Anat., etc., Berl., Bd. cv (1886), S. 28-46. — Ueber den I'rsprung und den centralen Verlauf des Nervus acusticus des Knninchens und der Katze. Arch. f. path. Anat., etc., Berl., Bd. cxix (1890), S. 81-9:}. II von Monakow, C. Ueber den Urspnmg und den centralen Verlauf des Nervus acusticus. Cor.-BI. f. schweiz. Aerzle, Bd. xvii, 1887, No. 5; abstract in Neurol. Centralbl., Leipz., Bd. vi (1887), S. 201. Ill iti , 1!" I (Jll()UlMN(} AND CIIAININ'C TodHTIlHU OK XKl'WoNKS. 50.-) Salii,* IIol(l,f P. Murtiii,J Cramer,* Kiiinoii y ('ajiil,|| and otlicrs. Tlicre aro, in accordaiico with tlio views of tlie majority of recent investigators, at least four well-defined ])riiuary nuclei of tormination in connection with the vestihular nerve: (1) The nucleus norvi vestibuli medialis (Schwalbe) ; {'i) the nucleus nervi vestibuli spiuiilis (radix deseendens) ; {'.]) the nucleus nervi vestibuli lateralis (Deiters); and (4) the nucleus nervi vestibuli superior (Flechsi'g, von IJechterew). In addition, the nervus vostil)uli comes into direct conduction relation, {(() (prob- ably chiefly l)y means of collaterals) with the nucleus nervi cochlea} ventralis; {//) (by means of ascending liml)s of divi(h'd root fibres or collaterals from these) with the mass of nerve cells (Ramon y Cajal's nitrjt'us rcrrhcllo-ariixtirnft) in the lateral wall of the ventricle, dorsal to Hechterew's nucleus, and (') with the nuclei of the roof of the fourth ventricle (nuclei fas- tigii) on ])()th sides of the middle line, and [il) possibly, accord- ing to Ramon y Cajal, by means of a few fibres with the nucleus ilentatus cerebelli and the cerebellar cortex. Concerning the exact topographical relations of the four principal nuclei, the descri),)tions in the I)ibliography are not only very incomplete, but there is also considerable variance between the statements of ditt'erent autiiors. Florence Sabin has made from serial sections a flat reconstruction of the exact limits of these nuclei as they exist in the new-born babe, and we * Sala, Ij. Siir rorif^inc dii iicrf iicoiistiiiuc. Aicli. ital. tie Ijiol., Turin, t. xvi (lH!»l-"!)-->), ii|i. 1!m; -JO?; also in JFonitore zool. ital., Firenzc, vol. ii <1891). j). -IW). t llelil. II. Die cfiitialcu Balmoii ili's Nervus acusticus bei der Katze. Areh. f. Aiiat. and Pliysi..!.. Aiiat. Ahtli., Lfij.z. (1S!)1), S. 371-201.— Die Endij^uiijjswcise der seiisi!)leii Nerven iiii (n'liirii. Arch. f. Aiiat. u. I'liysiol.. Aiiiit. .Vhtli.. Leipz. (1S!»2), S. I};j-;i0. — FoImm- eiiie direote aeiistisclie Kiiideii- balin und don Ursprunij dcs Vorderseitenstnin,i,'os helm Mensclien. .\rcli. f. Anal. 11. I'liysiol.. Anal. Alitli.. Fieijiz. (1«!)3), S. 3r)7-2(;4.— Die ceiilrale Ce- horleitiinf,'. Arch. C. Anal. 11. Physiol.. Anat. Ahth.. Leipz. (IHiKi). .S. ^Ol-'ilH. X ^lartin. I*. Ziir Hnditruiif; des Nervus acusticus iin Gehini der Katze. Anal. Anz., .lena, lid. ix (lH!):i-"!»4). S. 181-184. * Cramer. .V. I{eili'!i;,'e zuin feincren Anatonii(> der Medulla otilongala und der Mriicke mil liesonderer IJeriicksichtif^nni,' des ;i-I2 llirnnerven, Jena. 181)4. I! Hamon y Cajai. S. ISeitriiir ziim Sluilium der Medulla ohjonirala. des Kleinliirns und des I'rsprunu- der tiehirnnerven. Deutsche I'eiierselz. vuiti Hresler, Loii)zi-,'. l.S!)(5. Iti ii 506 TIIK NKllVOL'S SYSTEM. 1:1 Flo. 3155.— DiiiKnmi rcpn'spiitiiifr flat rcconstriictiDii of the nuclei iif teniiiiiatinii of tlieciiclilcaranil vestibular nerves, i After Florence li. Sal)iM,.lolins Hopkins Hosp. Hull.. Italt., vol. viii. isit", Fi>r. 1. i Tlu' line a. n npicsents tln' lat- eral wall of tile ventricle ; the line h corrcs|ion(ls to llic lateral outline of the corpus restiforiiu' ; the line il\ to lU. ili to ''a, and the line <■. f. c corresi)on(l to tlu' sulci in the tlo(U' of the fourth ventricle: ('.tion of the Cochlear and Vestibular Xcrves. Johns Hopkins liosp. Bull., Halt., vol. viii, 1897, pp. ^oS-^,-)!!. f It is rather amusing to find that in the earlier history of the vestibular nuclei the medial nucleus was spoken of by Schwalbe as the Ilaiiptkern dcs AcusticHS. Later the superior nucleus (v. Hechtcrew) was described as the Ilaupfkcrn di:s Acusttcus. It would be unfortunate if, in ajjreomint with Hamon y Cajal and myself, still others, coming to the conclusion tliat the nucleus of the descending root is the principal nucleus, should introduce a third Ilnuptkern des Acusticas ! I ii 5 -7 I f tin H ? ,i \' r)OS TIIH NKUVors SYSTKM. Deiters' nucleus as shown in the (liiif^nuii ( Ki<^. :{:}")). Posterior to it (that is, spiiiiihviinl from it) is situated the nueleus of tiie dosccndinf^ root, and tiic Junction of tiu' two nuclei is nuirked by a re^uhir vortex of fine inedullated fibres.* Kuavm Nuu. K'joam. Fio. 33(5. — Tr.msvcrso section of incdtilla ohloiiKitta and ('('rchclliini of n('\v)»irn child. (Scries ii, section N'o. lt(i. ' r.r., corims restifornic (tlie part nu'dul- latcd correspon'< < ;5 .5 ? ^ -i.'i .c S'C £ k .w ^— 2 >' f^i m Pi, t' ri' ^ 2- >:u|i;f^ 3 ; Kvi? = s = A ~ i<' 2 r - c - '■ . • s >^ i '• (iU<>l'lMN(t AM) CIIAININCJ TOCJKTIIKIl <»P NHrUoNHS. r^\i (lens to till' vcstihuliir roctt libiTS. Tlu' til)r('S i'nti'riii<,' as ii toU'nibly coinpiict bundle pi'iu'trate the iiii'dulla to the re^'ion of this nucleus, and tiien, suddenly stoppiiifj their dorso-niedial course, hifurcate, the eoarse descendiMj; liiiil)s passin) shows how Deiters' nucU'UK (Ii„ L) sits, as it were, like a cap upon the dosceiuUng root. The medial jjortion of the nm-leus L is separated from the lateral portion L, by the entering root flbres. •Inst how far down the fibres of tin- descending root go it is ditlicult to say. They can certainly be followed to a level pos- terior to the middle of the nucleus nervi hypoglossi. Hamon y Cajal has been able in the mouse to follow them below the gan- trlion commissurale of the tractus solitarius. What is the fate of the ascending liiid)s of division of the axones of the nervus vestibuli ^ The careful studies of v. Ki'tlliker, Held, and Ramon y C'ajal with (lolgi's method have determined their course. They pass in a (b)rsal and somewhat lateral direction, pursuing a tortuous .nid very irregular course into the nucleus nervi vestihuli superior, where all of them give off numerous collaterals and many of them eiul. The coarser Hbres among them i)ass up medial to the corpus restiforme ami terminate in the cerebellum in the nuclei of the roof of the i'ourth ventricle of the same and of the opposite side, and, ac- cording to Cajal, give off in passing collaterals to the little mass of lUM've cells situated in their course (his uuch'ttx rrrc- hcUi) oritsfini.s). The fibres of the direct cerelx'llar bundle of the nervus vestihuli are doubtless among the l)undles of medul- lated fibres seen in Fig. :]:i7, exteiuling between the region of Deiters' nucleus through Hechterew's jiucleus and the brachium conjunctivum to the region of the nucleus fastigii, though they do not represent the majority of these fibres.* It is impossi- ble, however, from Weigert-Pal preparations to say in every instance in which direction the fibres are running — whether from the medulla to the cerebellum, or from the cerebellum to the medulla. The connection of ascending limbs of vestibular fibres with the medial nucleus (its antero-lateral extremity, nucleus Y) r If * For a study o( the nucleus fastifjii hy (idliji's method, see Hainoii y Cajal. Ganglions eerebclleux. Bibliogr. anat., Par., t. iii (1895), p. 33. :i ¥■■: » 1 i*I 512 TIIK NKHVOUS SYSTKM. mill with DcittTH' luicli'iis appcarH to lie mainly l>y incuiis ot' collatcralH. In Wcifjc't-I'al prcpuratiotis cnoriiiourt nunilxTs ut' fibres are scon to enter nueleus V, hut it is iinpossihle to say Fks. 3:{H. — I'criccllnlnr riidiiiKs nf (■(illiilcriils IVinii the iixoiics nf tlic N. vislili- illi ill the iiiiclciis N. vcsliliiili lalcnilis iDcitcrs') of a I'niii-dii.v-iiM cat. ( After S. liaiiii'iii y < ajal. IJcilraK /.iiiii Stiidiiiiii dcr Medulla < )l)lnii).'ata. etc., Lei|)/.., ISiMi, .'^. '2. V\fi. Mil.) .1. de.seeiidinj,' liinl> cd' Idl'iircatimi of N. ves- tiliuli ; //. iiericelliilnr iietwcnk ; (', liiaiudies in wliiili niie can see the teriiiiiiaticiiis id' the ultimate lihriis ; if. cidlateral whiili. eiiteiiiiK into n iii't- Wciik. sends aimthei- coMateial I'd to iieii;lilMirinK raniilications. whether these are colhitenils or ascendinji; limbs of divided root fibres. The lower portions of the medial nnelena reeeive numerous collaterals from the deseeiiding limbs running; in the radix deseendens. A jjreat many collaterals from the fibres of the descendin, isoiatcd fihrooftlu' N. pi'trosus siipcrficialis iiiajor. space has been economized to the utmost must be of the liigli- est physiological significance. The central uxones of the cells of the geniculate ganglion f * Tlioiiios, A. Les terininaisons centrales Ue la raeine labyriiithique. Compt. rend. Soc. de biol., I'ar.. 10. s., t. v (1898). pp. 183-185. f Tills jjanglion in early embryonic life is a portion of tlie general fan- shaped (UxntjUan iicu.sfirofocinh' of Ilis. 'i'he (•('ntrii)etal (ilires arising from this ganglion decussate at the apex of the triangular ganglionic mass, and enter the medulla in the form of two hundh's — a lateral and a medial. The peripheral fibres diverge as the co('hlear and vestibular nerves. The motor facial nerve, whose cells of origin are inside the pons, breaks through this ganglioinc mass, carrying with it the group of cells corresponding to the geniculate ganglion. Cf. His, VV. Die niorphologische Betrachtung ■•, I,. I |.i M ■ t \ m\ jMiiilMiii ■"i ^i I 514 TIIK NERVOUS SYSTKM. (nervus intormodius) join, in all probability, the intracentral prolongations of the N. vagus and X. glossopharyngeus. Tiio poriphi'ral axones accompany, in largo part at least, tlie bundle of motor axones which constitutes the N. facialis (Fig. '.V.V,)). The cell bodies of the sensory neurones of the tit'nui.s tri- ffeniiiiiis are situated in tlie ganglion semilunare ((«asseri) (PI. I, Fig. -2). They are unipolar, like the cells of the spinal ganglia. Their luedullated central axones form the portio major of the lifth cerebral nerve (Fig. liiO). The peripheral processes of the ganglion cells are distributed to the skin of the face and the mucous membrajie of the mouth. The cen- tral prolongations plunge through the substance of the pons into the region of their nuclei of reception (Fig. ;541), where they bifurcate * (Fig. '-U'i), being thus distinguishable from the motor fibres of the fifth nerve, which do not bifurcate. f The descending limb of bifurcation is coarse; the ascending is fine, and termimitcs after rather a short course in that portion of the substantia gelatinosa often spoken of as the main nucleus of rece})ti()n of tb.' sensory portion of the trigeminus. In real- ity this is only the much expanded upj)i'r portion of the sul)- stantia gelatinosa. The descending limbs pass a long way down, the medullated axones forming the well-known tractus spinalis ncrvi trigeniini,J which runs through the whole length of the (lor Kopl'iiiTvcii. .\rcli. f. AtiMi. u. Pliysiol.. ,\nat. Abtli., Lei])z.. 1887. S. ;i79-4"):5: mikI His, ,Ir., \V. /ur Eiitwickfluiii^sgfschichU' di's .Vcustico- Fiiciiil.tct'hiftcs iR'iin Monsclion. Arcli. f. Aunt. u. I'liysiol., Aiifit. Al>tli.. 188i), Suppl.-I5(l.. S. 1-28. * Tlie i)ifurcjiti(in of tlio sensory axouos of tin- \. Injjfcinimis observed liy Raiiu'iii y t'ajal ((iac. sun. de Harcel.. 10 April, KS!)1) lias been conlirined by von Kolliker, Held, and van Gehuchtcn. f In Weigort-I'al i)reparat ions the sensory filtros of the \. trifjeininns are of fine calibre, and stain of a bru\vnish-i)lack eolor; the motor axones are much coarser in calibre, and stain of a deep bhiish-Vilack color. X Why even the first-class text-books persist in calliiii; this spinal Imndle the ascendiiifj' root of tlio fifth (the Germans constantly refei-rinj^ to it as the (HI fn/i'i'i/i'iide WiirzfJ) ] can not understand. 'I'liis is a serious mist ak(>, and notliinr is more calculated to confuse t'lc bejjjinntM' than the contiiuiance of such an erroneous nomenclatr"e. The fihwa dcsppiifl : theyan\in fact, the U'edullated descendinj,' limbs of the divided axones of cell bodies situ- ated in the Gasserian ijanirlion. I5y naminj;; it the "s|)inal tract of the tri- peminus." or tractus spinalis ncrvi triiremini. we avoid llii> confusion with the radix desccndens (mesencephaliea) ncrvi tritjemini. the me(lullaled motor axones descending from the nuclei motorii minores ncrvi trigemini. ■iS ^■£^ f GROUPING AND CIIATNING TOCJETIIER OV NEURONES. 515 medulla, going even below the level of the deeussation of the pyramids. These fibres on their way give oflf great Jium- bers of collaterals and terminals, to end free in the neighboring Fig. 340.— Corchrmn, with a portion of the spinal (■cfi, vie from tlic ventral surface. On tlic rifilit-iiand siilc tln' ventral roots , t oil' short and turned niedialward. ( .Vfter Kiireinini. the bundle is traversed by tlie root bundles of the X. glosso- ])]iaryngeus and X. vagus (Fig. 344), and by some of the tihnv cerebello-olivares. Just how far spintilward the tractus spinalis extends there seems to be a difference of opinion. According to (iudden,* it Itrobably reaches to the lowermost parts of the cervical cord. * Gtiddoii. 11. H( itrapzur Koniitniss dor Wnr/.eiii des Trigeiiiinusnerveii. Allg. /.tschr. f. I\vehiiit., ete., Borl.. IW. xlviii (l^ second cerviciil nerve, while von KoUikerf states that in the reijion of tho uppermost eervieal nerves there is no trace of tiie spinal Fill. :U:{. I,;il( tmI siiiiilliil srrlidii tlifdimli tiic |Miiis anil crrcliclliiiii dl' m I'li'Iiil II II 11 iM'. slinwini; I lie miimiiv porliiiii c if I lie N. Irificiiiiiuis. ( Al'lcr S. IJauii'in y (iijal. MiiliMi; /iiiii Studiiiiii ilcr Medulla ( >lilciii;;ala, clc. Lcip/., JsiHi. S. i, Viil. 1.1 .1. |iiirtiii iiiajiir cir sriiMny imit nl' N. irificiiiiiiiis ; tlif iiidis idiial axDiio dividing' iiiln an ascriidiiif; [n ) ami a dcsfciidiii^' liiiil) ( /i ) : c. tcniiiiial liraiiclics (il'asci iidiiii; liiiili ; d, niipt tilirrs wliicli >iiiU iiiln llic dc|itli ; c, dor- sal liart iit'dcxcnditif; iMUlinii iil' sciisdi-y nmt ; /.', Iiil'iircal Km cif axmirs of N. voliliiili. Ilic aMciidiny liiiilis ( ;/) t;ciiii;j in tlic (•(•icliclhiiii, the di'Mciidiiiu liiiilis if) yoiiifi diiwiiwaicl to llif iiitdiilla (ililmiwilii : ''. linicliiiiiii inn jmicliviiiii ; /', I'asciculiis (('rcliilhiiis ilcsciiidfiis ; /•', ciirinis rcslilDriiu •; /•'. Iciiiiiisciis lateralis ; //, eurims traiie/oideiilii ; O. iillrleiis deiitaliis. tract of the triireininiis. A little hiixher (about at tlu' level at which the dorsal nuclei of the nu'dulla begin) he finds the lower limit of the spinal tract. Cranier J traces it to the distal I'lid of the pyramidal decussation. It has been shown by (ioir norvosiMi ('t>ii- tral-OrpoK' in pviindcn ii. kratikoii /iistiindi'. 'II Anil., Leipzig (181*0). + <>/>. ril.. IM. ii. S. -280. J (>li. n't., S. o;j. u liOUl'lNd AND CIIAININO TOUl'miKR OF NKrilONKS. 519 =>§?£/-. §=<>'• t^'^s?! a S ± •> = c > i: I ,. = ■L = = = 5.y- 3 -.= •-■- -7, t-- = (!;.■-.■•=-- ^ . -r'C .- MS —• - '? i _ " •— -£ 2 - ~ ''^' i'il! 1 1 r 520 THE NEIIVOL'S SYSTEM. Tr.s.nt. •F.ctoF.r 5,g. Fui. 345, ill l:f it i:;M Fig. 343. — ircirizimtMl scctidii llinm^'li tlic iiicdiillii. pons, mihI niidhniiii ofa iicw- l)oni l)al)c>. \ViiKiTt-I':il stiiiiiiiij;. licvcl iili>tuiitin jicliitiiiDSi (il'ii iicwliiirii raliliit. (Al'IcrS. Kaiiiou yCa.jal, licitnif; /Mill Stiidiimi (Icr Mtdulla ( )liliiiij,'ala. etc.. HrcsU r, \a'\\>7... 1S!)(», S. m, V'lti- ~. ) .1. vcniral pari nl' Iractiis spinalis ; n, interstitial cells ; c, niavKinal cells; (/, cell islands ill sniistaiitia fielatiinisa : c, small cells nl' these islands; /.stellate uiant cells lint ai rallied in islands; ;;, inlerinsiilar cells: //, ll niai'f,'iiial cell, the axoiie ot' wliicli appeal's to {!<> into tlii' white snhstaiice or into the tractns spinalis N. tiiKeiniiii. OUOUPING AND CIIAINIXG TOGETHER OF NEURONES. 521 Fkj. 346. '1 ,-') 1 ')•} i)z TIIH NKIIVOUS SYSTKM. spinalis (one siipcrCiciiil aiul (•(tmj)iict, flic otiicr (Ici'pcr, and consisting of scvcnil hiuulli's separated from one aiiotlier l)v masses of f,'niy matter) are formed by (leseendiiif? limbs of bi- furcated root fibres (Fir's dinete Hi-nKiiriKrhe h'lt'inhiniltdhn. ^ Obersteiner. II. Anieilnng lieiin Sliidiuiii des Hanes diT nerv")sen ("en- ralorgane. Ill Anil.. Leipzig u. Wieii (IHOO), S. 40:!. 3,5 T '-^ <^ "''% IMAGE EVALUATION TEST TARGET (MT-3) !.0 I.I 1^ 1 2.8 m u I 40 1.25 1.4 12,5 2.2 2.0 1.8 1.6 6" Photographic Sciences Corporation ^o 1% myliend centri{)etal neurones mediating taste impressions — Xcrvas glos- sopharyngeus — Xervus trigeminus — Nervus iiUermedius — Taste buds in tongue — Heliitiuii i>f nerve fil)rils to taste bud — Intrageniuud fibres — Intergcmmai fibres — Specific taste (jualities — rerii)lieral eentripetal neurones mediating olfac^tory impressions — Perikaryons — Distal hair- like processes — Noii-medullated axones — Tenuiiialion in olfactory glo- meruli — Hegio olfiictoria of nasal mucous mcnibnme. 1. Peripheral Gustatory Neurones. Cnsfafori/ Xciiniitc.'f. — The periplieral sensory neurones mediating taste impressions cotisist of a portion of those of the nervus glossopharyngeus and probably also of tlie nervus trigeminus and nervus intermedins * (Plate I, Fig. "2). In gen- eral, what has been said regarding the collection by the sensory neurones of the spinal and cerebral nerves of bodily ini])ression8 holds also for the nerves of taste. The peripheral branches of the ganglion cells concerned in collecting taste impressions come ultimately, however, into contact in the mouth and tongue with ccrtiiin peculiar structures — the so-called taste buds.f The structure of tlu'sc bodies is well known and has been accunitely described in the text-books. They are egg-shaped or barrel-shaped masses of epithelial cells situated mainly in the vallate papillne and fimbria*, though a few of them are sciit- * In this conneetion the (taper of A. V. Dixon — <>n the Course of the Taste Fibres, Edinb. M. .1., n. s., vol. i (IMiiT), \t\>. 'M^i-iOl — may be consulted with profit. f These bodies appear to have been discovered independently by lA)ven and Scliwalbe in 1H67. r.'ir. \ I . t! I il ;)'. 526 TIIH NKKVOIS SYSTKM. tored olscwliore over tlio toiiijue, in tlic soft palato, and on tlio opiglottis. Dissu * lias ivcuntly (k'scribt'd similar structuri's as Nil W'il. v. Cone. — Siipporthifi cfll. yriiritriH'llicltal ,-,'11. AL, Rod Cfll. AVccc lihn'l.'i. Fifi. 347. — Si'liciiiatic rcprcscntatidii of a taste liiid. lAftcr Hrnnanii, Sil/iiiij;sli. (I. k.-lia,\ cr. Akail. <1. \Vissciis opitlu'lial jwrt of tl.c mucous membrani'. At least two sorts of cells are present in each taste bud: (n) the supportinjjf cells consisting of an outer layer with nuclei centrally placed, and an inner layer of very delicate cells with nuclei situated at the base ; (/>) the sensory cells, the so-called neuro-ei)ithelial cells of the taste buds — delicate long- drawn-out cells which stain well by (iolgi's method, and which send a hairlike process through the pore at the apex oi the taste bud to the surface of the mucous meinbi:n;e. It is proba- ble that the flat cells at the l)ase of the taste bud correspoiul to a special form of .uipporting cell (Fig. -W). The nerve fibres, as von Lenhossek f and Uetzius J have shown, end free in * Dissp, J. Ucbor Epilliollinosiicii in dcr I{('y:i() olfacloriii der Siiuger. Ntu'hr. V. (1. k. Gescllsch. d. Wissonscli.. (Jottiiij,'. (1H!)4). S. 6(5-71. t voii Ii('nhi)Si=;('k, ]\I. Dor feinero I5aii mid (bo XorvonoiKb'guiifjcu ilor Ciosohmacksknospon. Aiml. Anz.. .loiia, lid. viii (lH!»'i-'9:?), S. 121-127. I Kotzius, (J. Dio \i'i'voiioiidijjiiiijj:oii in dem Uoschinneksurfjfau dor Siiiiijctioro mid Aniphibioii. IJiul. rntorsuoli., Stockliolin, n. F., 15d. iv (1S!)3), S. l!)-;{3. I'i. I UllOUPlNG AND ("llAlNlNd TOOKTIIEK OF NHIUOXHS. ^liT iiiiioiig tlu! cells of tho tiistc hud. Tlu' old idcii that the iiciiro- cpitiudiiil (iolls <;tivc off iixis-cylindcM' procosses which ran to the nerve centres has been detinitely disproved. It is to be reiiiemhered that the nineous nieinhranc of the toTi^ue is supplied in j^t-neral with nerve endinjjfs niediatinjj the sensations of touch, pain, and teniperature just as is onlinary skin. In addition it receives the nerve fibres uhich })ass directly to the taste buds. The nerve fibres approaching,' the taste buds and beconiinif coiuu'cted with them (intrar cell; lielow the ta^te b. id a snlpijemmal cell is in- dicated ; /(, the bejtiiiniiifis of the nerve librils iijton and between the taste buds. individual fibres formin<( a complicated plexus about the con- stituent cells of the organ, though without entering into any i; jiM r>-2^ 'I'lIK NKUVors SVSTKM. rcliitioii otlitT tliiiii tliiit of contiict with iinyct'll iind jippiU'ontly witlioiil tlic I'oniiiitioii of aiiiistoinosori iuii()ii (•(iimcitccl witii llir (irKiOKin j;ti>liis. I Alter \V. vein Hi'ditcrcw, I>it' lifitimysliMlnun im (itliini uiid Itii( kniiiuuiv ; Dciitscli vuii K. \V4'iiil)crj;. Zwtilc Ailll., \y\\y/... 1S!I!I. S. 1st. Via. l.ll. 1 j/x. Klaiidiilii siiliiii:ixilliiiis ; iil. lu'iviis liiifjiiiilis ; jic. iiapillir vallatu' ; I', ncrviis tri;;<'iiiiiuis ; 17/. iutvus iiiti'i'incdius ft facialis ; /.V. iicrviis KJossopliaiyiiKctis ; I",, .N. oplitlialiiiiciis ; r,,, N. inaxillaiis ; 1',,,. N. ii'aiidiliidaris ; jm, jics anst'i-itius ; :iii. N. aiiricu- laris ; fsl. fdraiiun styioiiiastdidi'mii ; flit, clionla tyiiipaiii ; /i/>.v, N. pftmsiis siipci'licialis major; (/.v/i. K^mfjlii'ii spliciio-palatiiiiiiii ; ;/ 1', wi'itrlion sciiii- liiiiaic tlassci'i ; r.oil. corpus callosimi ; ./'<;, coiKliictioti patii for tasti' to tlic ccrcliral cortex; /;;■•.■, corpora i|iiadrif;eiiiiiui ; iil, nucleus ieiitiforniis ; lli, tlialanius. Concerning tlie existence of several typos of taste buds of specific structure I'orresponding to specific taste qnaliHes, we have as yet no data, nor are we informed at all concerning any special nuclei of termination of the taste fibres in the medulla and pons separate from the other uerve tibres of the three sen- sory nerves involved. imf^A I GIlOUPINd AND CIIAIN'ING TOOKTIIHll OF NKUKONKS. 52'.t A j^t'iuTiil scheine of tlu! tusti' coiKluctioii paths has ht'cii prc'pari'd by W. v. Hechtorew. It is reproduced in Fig. '.UU. 2. Peripheral Olfactory Neurones. ^rhe olfac^tory neurones of tlie tirst onh'r extend from llie miu'ous meinbrano of the iu)se to the olfactory l)ull). Tlie cell bodies of these neunnies are, reniarkal)le to state, situated aetually in the mucous nuMubrane of tlie nose itself, thus dif- I'erinjx from all other ju'riplieral si'iisory nein'ones (in human beings).* It had long been known that in the olfactory region FiCf. 'MSO. — Schcinc of tlic <'imrs(' fdllowcd liy iii rvc iiniml ;i|i|iiH';iliis 1)1' iii;uiiiii:il.s. (AftfiS. Uaiiii'iii y ( njal, i-cs i Tniiisl. Iiy A/.ouhiy, I'aris, IS'. (illhitury j^'Ihiik riiliis in luill)!!. oUhctDritis tnictus (ilfiictdriiis ; A,', (lU'aclury " ;;nmiil(s" : /•', adjan f.', n'Kiiiii iifsliia oHactdria lateralis; /, tullalcnils of the ii'lls ill till' oll'acliiry liiill) : //. cdllatrnils ol' tlicsc same ; (illiirtiiiiiis : /,, eeiitril'ii^jal lilue leriiiiiialiiif; in the Im (iiilfji cell of 'I'ype II (ir (leiidraxDne. riic arrows .sliow impulses. ses III lonvell iictoiy ; ('. Ill •lit pyr axoiies ixoiies llais ol tliedi the uU\ es it lee- miiniiis ilia I . eells; mitral lactiis is; .V, of the of the nasiil mucous membrane cells of two kinds exist — su])poit- ing eells iind sensoi-y ei)itheliiil cells, the latter being delicate narrow ct^lls provided with hairlike processes which project slightly upon the mucous surface. Max Schultze,f in ISli'-*, dis- * It will tints bo seen tliat in the iisisiil iiitieotis inoiiilii'aiio of liiiintiii be- iiifjs we iiicot willi a sensory apiiai'atiis iiiorpholofrjcally very .similar to that wiiieh has tieeti deserilx'd in tlie epithelial siirfaee of the fish worm. f Scluiltze. M. Ueberdie I'',iiilimiii<;s\veise(ler(iertt('lisiierv(Mi ttnd der Epi- tlu'lialgeliildo der Xasonsclileiiiihaiil. I5er. d. K. I'retiss. Akad. d. Wissnnscli. zti Berlin (IH.IG), .S. ,'(()4-r)14. — riilersticlitinpMi tiebcr den liaii der Nasen- schleinihiiiit. namentlich die Struct it riinil Kiidif^tiiifjsweisiulertiertiehsnerven lieiin Meiisclien nnd den \Virl)eltiereii. Abliandl. il. Niitiirf. (iesellsoli. /,ti llalle, Kd. vii (IHG'^). — Das i'',pitlieliuni iler IJieehsidileimhatil des Meiiselien. Centralbl. f. d. mod. Wissensch., IJerl., I'.d. ii (I«04), S. 1585-390. 1 il \' t: H ■T' i \ i f r)8<» TIIK NHKVOUS SYSTEM. covered that from the proxiiniil end of each olfactory cell an olfactory nerve fil)rc took its orijrin. The use of the inethylene- blue inetliod by Khrlich * and Arnstein f and tf tiol«;i's nietliod by Kainon y Ciijal ;]; and van Cehuchten * has proved beyond Kid. 351. — \ Kldiiicruliis (ilfai'tdi-ius from ii youiif; cat : iiictluKl of (icilf;!. ( .Vftir .\. von Kollikcr, MuikIImicIi (Iit (icwclii'lflirc dcs .Mfiisclicn, lid. ii. lA'ii)z.. IH'iti, S. 7(11. Kifj. 7r)4i. F). The nerve tihres whicii end free in the inueous inenibraiu' of the nose indei)endent of olfactory epithelial cells probably be- long to the nervus trip'niiiius, and have nothinjr directly to do witii the carryiiiir of olfactory impulses. !i!!!t ?, H 1 Fio. 352. — Area of iiasil iiiucims inciiilifiiiic wliicli. aiTiirdiuj; to tlic rcst-arclics of V((ii Hniiiii, is iimrrvalcd liy Nii. oll'actdrii. The axones of the olfactory neurones are uoJi-iueduUated. They pass throuffh the cribriform plate of the ethmoid bone in bundles (Xn. olfactorii) to the olfactory bulb which they enter.* Here they terminate, as (Jol^i first proved, by free end-arboriza- tions in the so-called olfactory fjlomeruli, comin,")7 stpuire millimetres. In a se(U)n(l case the distribu- tion amounte(l to "i'-iS millimetres (Fig. 35'^). * von Hrunii, A. Rcilni^^e zur iniki'uskoiiisclit'ii Aiialoinie der iiioiiscli- licheii Xasenlinlile. Aivli. f. iiiikr. Anal., licmii, IM. xxxix (IH!)-,'), S. (J;{2- (551. , •ill 1 i T-pB '■.U 3. Peripheral Visual Neurones, niAPTKU XXXVII. TIIK PKKIPHKUAL VISL'.VL N i:r ItON i:S AM) TIIK STKrcnKK Ol TlIK KKTINA. Oilier studies of tiic rctimi — Its liimeilatioii — Studies of 'I'urtuferi, Ramon y ("ajal, and l)o;;ii'l — (loli,'i prfparatioiis — 'I'lie rod ceils and cone eclis — Tliu l)ipoiar celis — Tiie f,'aiif;iion celis and optic nerve tilires — Superini- position and inlerreiiitions of tlie retinal elements — IMiilier's littres— The amacrini; cells — The horizontal cells — ( 'omparison of the periph(>nil visual neurones with other peripheral centripetal neurones — Von Len- hossek's study of the cephalopod eye — IJeduction of elements in the visual conduction i>ath. Vixval Neurones. — The peripheral sensory neurones con- cerned in the sense of sight are situated in tlie retitia. Tlic older ideas of the structure of the retina which most of us were taiij,dit in the nu'dical schools were extremely complex, and tlu' memorization of the exact ])osition and appearance of the vari- ous layers of this memhrane was hy no means easy, since the intraretinal rehitions and connections of the elements were en- tirely ohscure. It will he recalled that externally next to (1) the layer of hexagonal pigment cells were situated {'i) the layer of rods and cones. Then followed, ])assing inward, {'■]) the outer nuclear layer; (4) the outer molecular layer; (r>) the inner nuclear layer; (d) the inner molecular layer; (i) the layer of nerve cells, ami, lastly, (S) on the inner surface of the retina, the layer of nerve fibres. These various layers were easy to make out in preparations stained M'ith ordinary nuclear dyes (Fig. '.in'.]), hut as to wiiat the individual layers meant, and to exactly what cells the various nuclei aiul ])rocesses belonged, there was much dis- agreement. Instead of this unintelligible classification based simply upon staining iippearances and without any rational interpretation as regards the internal connection of the elements, the newer studies 533 li! 1 1 fH .-!»" . (i < I r)34 TIIK NKIJVOl S SYSTKM. (»f Tiirtiiffii,* Hiimoii y ('ajiil,f Doj^'icKJ mi'l <'tli('rH liiivc tini<,'ht us what tlicsf v!iri(His layers tiicaii. IT (»nc will conifjarc l-'i;;. :}'»;{ with the silvcr-pictiirc of the retina ( Kij:. :jr)4), the eiKirtiioiis Kiinplifieatioii wiiich liiis resulted from the application of (IoI^m's method to the study of this iuend)raiie will he immediately ap- parent. The silver ehromate method shows that in the retina, in addition to certain more complex relations wliieh exist, three very distinct si'ts of cells are superim])osed : (1) 'I'he (U'lls to wiiich the rods and cones belonjf ; {'i) the l)ipolar cells; (;{) tlie <.fanloj,'ic el Ics I'oiuiexions des I'lt'nu'iils dc la ri'liiie des oiseaiix. Anal. .\nz., .leiia, Md. iv (18f), S. 111-131. — IV'(|Uc'nas contriljiicioncs al conininiicnlo del sislciiia ncrvioso. III. La retina de los liatrauios y rejitiles, Aj,'oslo (^IN'Jl). — Nolas prcveiitivas sobre la retina y gran siinpatiiM) de los nuunifcros. Marcclona I)ic., ISIM. — La ret ina de Ids Telosteos y aleunas oltservaeiones .soltre la de los vertel)rados siipcriores, Madrid, 1S!I2. — HI nuevo eoneepto de la liistologia do los ccntros nervioso.s. Uev. de cieii. ined. de Hareel., vol. xviii (1HI)2), p|). ;{f!l-l{76; 457-4Tr>, etc. — La rcline -4'JS. — I)ic Retina der Wirlicltliiere. I'lilcrsiicluingen mil dor (Jolgi- Cajarsclien Cliroiiisilhcrnictliodc and der Klirlicli'sclieii .Metliylenlilaiirilrb- uiig. In Verbindung niit dem Verfnsser zusainmcngestcllt, uebersetzt, und niit Liiileitiing verselicn von R. (treef, Wiesbaden (1804). X Dogiel, A. S. I'eber das Verlialten der nervt'isen Klcinento in der Re- tina der (lanoiden, Rejitilien, Vogil, uml Saugethiere. Anat. Anz., .Jena, Hd. iii (1M8S), .S. KiH-U;?.— Uebci die nervosen Eleiiiente in der Netzliaut der Ainpliibien und Viigcl. Iliid., IJd. iii (1888), S. ;{42-;{47. — L'eber die iicrvc'iscn Eieniente in der Retina des Men.sclien. Areli. f. inikr. Anat., Honn, lid. xxxviii, S. ;517-Ii44. — l'eber die nerviisen Elemente in der Retina des Menselien. Arch. 1'. niikr. Anat., Roiin, lid. xl (18i):2), S. :21»-;58.— Zur l-'rage neber den Ban der Nervenzellen und ueber das Verliiiltniss ihres Achsoncyl- inder-(Xerven)-F(irtsatzes zu den Proto|)Iasinafortsatzcn (Deiidriteii). Arch, f. inikr. Anat., Bonn, Bd. xli (18!»;i), .S. G',>-87.— Neuroglia der Retina des iMensehen. Arch. f. inikr. Anat., Bonn, Bd. xli (1893), S. G13-G2!5.— Znr Frage ueber das Verlialten der Nervenzellen zu einandcr. .Areli. f. Anat. u. Phy- siol., Anat. Abth., licipz. (I8!»;{). S. 4',"J-484. * For one ganglion cell there are about one hundred rod and cone cells. ■ (}U()UlMN(i AN1> CIIAININ*; TOOKTIIKU OF NKIUONKS. y.\rt midciir liiyor corresponds to tlic luiclt'i of the ('('lis whose distal processes represent tlie rods iind cones, while the inner nuch'iir layer corresponds to the nuclei of the hipohir cells. The outer molecular layer represents the reijion of contact or concrescence relation between the proximal processes of the rod and cone cells and the distal processes of the bipolar cells, while the in- ner molecular layer corresponds to the region in which the ter- mi K I r)3«? THE i^ERVOUS SYSTEM. minals of the proximal processes of the bipolar cells enter into contact or concrescence relation with the dendrites of the ganglion cells of the so-called " layer of nerve cells." The layer of nerve fibres represents the axones arising from the cell bodies 2.) r) : I'l; I've ; ''■ lie) Hill Fio. 354. — Sflicmt' of tlu' stnictiirc of tlio ri'tinu. (AfU-rS. liiimoii y Ciijiil, Ketiiiii (lor Wirbcltliifrc, rclxTsct/. v. (irccrt", Wicsli.. WM, S. 17, Fif;. -1. layer of rods and cones ; //, bodies of visnal cells (external nuclear layc C. external plexiforin layer ; /•', layer of l)iiMdar cells (internal nu;lion cells: //, layer of ne fibres: ((. rods; /(, cones; c. bipolar (rod) cells: /. bipolar (cone) cells lower brani'liin;; of bipolar ( rod i cells ; /'i, lower brandling of bipolar (co cidls; (j.li.i.h, KaiiKlion cells brancliinj; in ditferent layei's of tlie inte I)le xi form zone ; .r, contact between tbe rods and tlie bii)olar ( rod ) cellt^ contact between the cones and tlie bipolar (cone) cells; t, Miiller's cells centrifuftal nerve fibre. in the " layer of nerve cells." These axones pass over the inner surface of the retina to reach the blind spot of the eye where they penetrate through the whole retina iind make up the con- Btituent fib''es of the optic nerve. The nerve fibres of the optic nerve undergo partitil decussiition with those of the opposite side in the optic chiasm, and pass through tlie optic tracts to terminate in the corpora quadrigemina, lateral gtmiculate bodies, and pulvinar of the two sides ( Fig. ;?5f)). These three sets of elements — the r ^ and cone cells, the bipolar cells, and the ganglion cells — represent the principal GROUPINU AND tIlAIN'IN(J TOGETHRR OP NKURONKS. 587 morphological constituents of the retina. There arc, however, certain otlier cU'monts present in tliis nienihraiic wliich must he mentioned, though tiieir rehitions to tiie principal elements, whil'^ they have been carefully studied, are not yet satisfac^torily understood. These are (1) the so-(!alled Midler's fibres (spongio- lilasts of His), whieli correspond to the ependyinal framework of the spinal cord and brain ; {'i) the so-called amacrine * cells of Ramon y Cajal (also sometimes called spongioblasts), which occur in the inner molecular layer, aiul which appear to be G.c.a. _ Kasal port.««t * "^"^'^"'^ ■ Ckiasma opticiim 1. f ^«- Ped.cer. ^-■'".rr,. "n. •«««. \ ^- — I Pulvinar of ^ * ^ Thalamus Cgtnjit C.t. C.i. N.lrochlttriK TtiiipBf«l p»'l«n Fio, 355.— Sclu'iiu' iif visual (•(induction iintli. Lettering same as for Plate II, ri«. I. anaxones; and (3) the horizontal cells, outer and inner, of the outer molecular layer. a privative, fianpos long, and iws fibre. liiii? \ t i\ m ,53S THE np:iivol's systplm. Fig. ;!.")().— Ki)itlu'liiil cells (Miillcr's (ilircs) of tlic rctiim. (After S. Hiiinnii y Ciljal. Die Retina der Wirheltliiere, relirrsetz. v. (Jreelf. \Vi<>sl)., 1M<>4. Till', vi, Fifjs. I iiiid 'J. ) A. Miiller's tiUns fi-diii tlie ri'tina of the fro^ : (/, extci- mil iiiicleiii' layer: /i, external plexiforni layer: c. internal nnelcar layer: (/, layer of spon^iolilasts ; c. internal plexiforin layir; f. layer of fjaiiKlion eells; ;;, hasti layi'f or uieinlirana liniitans interna. B, Miiller's tibris or oi)itiieiial eells from the retina of Cypriinis earpio. ifijill Fio. 357.— A section tliroimli the retina of an adult do};. i After S. Kanion y Ca.jal. Die Retina .) ((. cone tihre : h. ^jraniile an11 witii ascendiiif; eiid-hrnsh lieloiifiinf; to the rods; i\ liipolar cill with end Iniish s|)read out tiatbe loiurintr to the cones; /. ttiniil l'il>olar cell with('nd-l)rnsli spread cint Hat ; /(, dilfiise ainacrine cell, the varicose hranclies of which lie for tlie most part directly iii)on the Kanj;lion cells; /', ascendin^' nerve lilires; .;'. centrifnjial tlhres : nish of a liipolarcdl (hstiiied for the rods: ih, nerve lihre which hccomes lost in the inti'rnal idexiforiu layer; }>, nerve lihre of the oi)tie-lil)re layer. . ' rrIlOUl'lN'(} AXl) CIIAIXING TOGETIIKIl OP NKUKONES. 531) The shape of Miiller's fibres is shown iji the accompanyinji; figure (Fig. :{")(;). It, is not improbable that they represent sup- ])()rting eells. Tlie anaxones (aniacrine cells) represent, in al' probability, mechanisms for correlating the activities of the different neu- rones (bipolar cells and ganglion cells) with which they come into relation in the iimer molecular layer. Since it is exactly Fill. 358. — Xcrvc cells (if the rctiiui of the ox. stained with nietliyleiii' hhie ; iiietlKiil (if Khrlieh-Dofiiel. (After S. RniiK'ni yCiiJiil, Die Kediia der Wir- lielthiere. reliersetz. v. (ireelf. W'iesli.. ISitl, Tiif. vii, Imk. !(. I This liKiire slidws tlie extertiiil (ir siiiiill iKirizoiital cells, n. cell IkkIv eoiitaiiiinj; vev.v intense lilne .pdts ; h, very line and innch-bran(died dendrites; c, ax(ines witliiiiit visiltie collatenils ; (/. sinjile axis cylinders wliiidi (iften liraiicli and which iir(>l)iil)ly arise from the lar^e or internal horizontal cells. in their neigh])orhood in the retinti thtit the few centrifugal fibres of the optic nerve terminate, it is not impossible that the influence exerted by the cerel)ral centres upon the retinal activi- ties is mediiiti'd by these cells (Fig. ;}o7). 3G t J m 1 540 TIIK NKIi vol's SYSTKM. 'I'lic liorizoiital cells of the outer nioloculiir layer can be divided into two ^M-otips — an external ^n-oiip {ccUtdc KKpcrJicidli (li ijrnitdvzza media of Taitufcri) .iiid an internal set (lar^'^o superficial cells of 'I'artufori, largo and small stellate cells of Dojriel). The external hiriznntal cells are very numerous, and have loiifi^ diverging,' dendrites, whicdi spread out to form a thick plexus (Kig. .'558). Their axoiies are extremely delicate and diflicult to find, but are described by Ramon y ("ajal as coming off usually from a dendrite. The axones and collaterals are distributed in the superficial portion of the outer molecular layer. The inner horizontal cells (Fig. ,35i)) are of two sorts: (a) Those with descending dendrites, and {b) those without de- Fuj. ;!")!». — A pcrix'tiiliciilar section tliroiijjii tlic ictiim of the nx. i.M'tcr S. KaiiKMi y ( ■;i.jiii. Die Kctiini ilir Wirlicltliii re, I'dx rsctz. v. (irtcll', Wicst)., ISitl, Tilf. vi, I''ij;. 1~. ) n, internal li♦' rotls with other (U'liuitc {^fniijw \yiu^ at 11 distiiiicc. The question ut once arises, Wliich of the elements mentioned are to be h)oke(l upon as the jieripheral visual neuromas analo- gous to tht? j)eri})heral sj)inal centr'petal lu'urones and to tiio peripheral olfactory neurones!-' Tiiis (juestion is not so easily deeided, and is nuide more complicated by the fact that the whole retina arises embryologically {rii/e Section IV) from the central nerve tube, and iu)t from a separa*^e basis, as do the spinal and cerel)ral ffaiif^lia. I i)n'fer, though i.iiis opinion may not be sluired by all, to look ui)on the bipolar cells of the retiiui as the analogues of the spinal ganglion cells; their distal j)ro- cesses are then comparable to the afferent libres in the ])eriph- eral spinal nerves, and their proximal ])i<)cesses to the axones of the tibres of tlu^ dorsal roots. The rods and cones would then correspond to dilTerentiated epithelial ejtendymal cells* with which the peripheral processes of the bipolar cells come in con- tact, just as the so-called neuro-epithelial cells of the taste buds in the tongue stand in contact relation to the ])erii)heral fibres of the glossopharyngeal and other cerebral nerves, or as the TitstzoUcn of Merkel are related to the peripheral processes of spinal-ganglion cells. The axones of the bipolar cells would find their "nuclei of termination " in the outer molecular layer and in the ganglion cell layi'r of the retina; the latter would l)e analogous then to the gray matter of the s])imil cord and me- dulla (of the general spinal sensory paths), to tln^ nucleus ahe cinereie and nucleus tractus solitarii (of the gustatory con- duction path), and to the olfactory bulb (of the olfactory sen- sory conduction path). This would make the ganglion cell layer of the retina, the ojjtic nerves, and the optic tracts parts of the central nervous system. 'I'Ik^ o])tic nerve is then, in a sense, not a peripheral nerve. Inasmuch, therefore, as we are here considering only the sensory lU'urones of the iirst ord(T, the oj)tic lu'rve and its conrsi' and termination will ])e tlescribed when the sensory neurones of higher orders are considered. It is only fair in conclusion to state that the recent studies of * This view is all the more enticiiif? in tiiat recent stiiiiies tend to show that the outer limbs of tlie rods and clones represent structures formed of (lie cilia of the ependyiiial cells coiled up and ;,diic(l toj;cthcr. Cf. Krause, W. Uelicrsicht der Keiuitnisse voui Hau der Ketiua ini Jahre 1H'J5. Schmidt's Jahrb., lieip/., Hd. ccxiix (iy!)()). S. 90; 201. Vi 1 I Ml* TIIH NKKVOl S SV.STKiM. L / r,hs. IiikIii.i III ic Kll/ l'<7/». 4 (!l{(»I'IMN(iI-yniKU -tF NKUIIONKS. r.lM ■ i M. vuii liCiiliossrk ^ iiKik" il cxtrciiirly |H'(iliiililr tli;it tlir rnil iiimI i'uik' cells ill some iiiiiniiils :ii'<' n'iilly true |M'ri|ilicnil visiinl iiciiroiK's ( l'"i^'. )!<•<»). It" litis lie true, tlicii llic I ipdliir cflls of llic rcliii.'i niust. in siu'li iiiiiiiiiiis In- rc^rjn-dcil ns visiiiil sensory lUMintiicH of the Kceoml order. Tliere is no ohjeet ion, ho I'lir as I know, to conHidcrin^f I lie rod cells nnd cone cells of llie rel inn of luiniiin Ix'inf^s ms iirlinil nvunnics. No iinido^^ons cell is, liow- ever, existenir in llie oll'iictory tnncons inendmme. In nninmiiils two kindsof \)\\)iAuv ci']]^ (iir/n'/rtifi/i/ spr(i/,iii(/, o|»l!<' nenrones of t lie lirst onler) occur: (I) liipoliir cells for llie rods, willi verticiil end-tufts, wliicli enter into condiielion rela- tion with llie terminal s|tlieriiles of t lie rod cells, and ('.') hi|Milar cells for the cones, the dendrites of which form end-tufts, which lie ilia deeper |ilane than those for the rods; these end-tnfts enter into eondiK'l ion relation with the terminal hiil^nn^^s and lilirillu) of the cone <'ells. 'The hipolar cells nearly always conio into conduction relation with several of the roil cells, or of the cone cells. The niimlier, however, varies; whih' one bipolar cell may stand in relation to only a few, atiother may he in a position Id receive impulses from a j^'reat many. In the fovea centralis, where the niimher of cone cells is enormous, the indi- vidual c<»nes are very delicate, and the hasal swelling,' of each cone comes into contact exc). In the plcxirniiii layer, the ant neli I Ik muMs ilenients only, llie ^lia eel Is, ..' ((H, are represented. Of the eleiiieiils nt' llie inlernal t;raiiiilar layer (.'>,.';,.';), the cells 7 (»■) cnr- respdiid til the sinaller, the eell .'. if) In the larjier variety iif internjil t;raiiiile cells, 'riieir a xinics K" dn" n iiiln the inednllaled siihstance to end (herewith free rainilicaliiiiis ( hypnthetiean. In the niednllary layer the cells arc lit' the nrdinary type il!,i:,i;) that is, cells with desceiiiliiii; axoiies, (if which (here are sinaller. li (ip, and larger, '/'/i l. examples. The cells, .{(/', represent the rarer t'lnin nainel.v. the cells with ascendini; axmies; linally. at the hiittnm, is slmwii a very laru'c ^iaiit cell, /' (i), which sends it.s axiine, as dn iniist nf the cells in the medullary la.vi'r, into I ' pediimde. :. f! < iiAi"i'i;ir \\ WIN, TiiK iM:i{ii'iii:iiAi. Ai niioia mi hums am. tiii. simiim, (tUtiA N i»l' ( oitTI. Tl.o iirrviis .•urhlo.r (Jiin«lj.,n s|.in>lo-Tl. ..•Iil,.nr rn„( ..f (|,.. «,.,.„>.li,. n.-no IVriphonil pnicossos mi.l ll... ,.ipm of (',.r(iC..|,tial M\n,i,.s-. NM.l.-i,.fi..,„.inMli,.i, Hilniv„li,.nnf,iv„„,.s--T.Minn.M|.Mn.lcnll,il.-n,ls. 4. The Pnriphflral Auditory Neurones. Till iM-ripli.'nil n.Mirniirs ..f il,,. :ni.lilurv put lis ;iiv tli„s.. wliirh .-m.T int.. tlu' l'oiin;iii..ii of Hi,- m.lix ,M..'li|,.iiris N. to- fr A? Via :?(!1, Til.- l;il>.viintliii> iii.'tiil.niiiM.riis oC tli.' lifjlit iiil.iiinl v.n- u( :i Ininnn .iiil.v.vonl 111.' lirHi in..iilli. M'.'ti (Vo-.n llw m.'.linl -i.l.v ( Mi.iMi K'rtzius 'is sliulilly ino.litir.l l.y A. K'mii1..t. 1 / i, iil li. iiliis ; .', ivic^siis ill li.iili ' ' ; iiiM.ul:! M.uMi.M iiiii.iili : ;, sinus pcsiciior : .>. sinus Mi|.rii,.i' <: Miiiiitilli in.nil>r;inM..'ii sni..'ri.n- ; .'. miiii.iiIIm ni.'inl.r.iiiil.c;i l;il.'riilis ; .v, :iin|inll:i niciii l>i:iii:ucn nosicnor: ;*. .lii.tiis s.'iiiiciiviilHiis siip.Tlnr ; /(*, .in.ins siniirir .nlMiis iiost.'iii.r : //. .liirtiis scnii.in iilniis hil.'nilis ; /,'. wiil.'n.'i! niniiili „f .Ills siini.l.N ol llir 1:ii,t:i1 s.nii.iiviii;ii- .iin;!! .iponinn inlollic iiiiicnlns • / ; siK.iilMs : /;. ni;i.iil;i .-i.nsli.M smnili ; /.I. .lii.'liis .-ii.lnlviii|.li.ili; \ .|,iisli,i|s £>/. N. \.>slil.nli; .','. \. s'l.ciilnris ; .'.>', \. !ini).nll.iiis iniriior ; '; N ,.,„.||.' li-iv; -'•>. .lislnliiiiKiii 111 \. .oihlrn. wiihin tin- l.iniina spiriilis ossca .■.44 i. /I) (JIJiMMMNO ANIi CIIAININO TOOKTIIKU <>l' NKHUONKS. f. ITi iiciiHliii, nr Hd-nilli'tl riiTviiw cmiIiIcii' * ( l''i^'. ^I'll). 'Ihc i<|| Ixidii'M tin* Hitii:it*>i| in tlx' ^'iiii^liini s|iinil)' (kiiii;^'Iii)|i oI' ('(uli) wliic'li licH ill I lie liniiy cnclilcii f (I'iK- 'K'*). 'I'licscf (('liH rciiiiiiii ?v / l''lii. :t(l;.'. — Hrctiiiii llii'Mii)>li Mir <'iii'lilrnr iTj^iiin kC tlic liiliyriiilliim ossciis el iiii'in- liiiiiiiicciis hI'm (initMii pi^. lACIiiA. A. I'ihIuh iiinl M. vnn Ikividud', l,ctir- lillrli ijcr IIM.ildHi.' (Irs M.iimIhti, (•(<■.. Wiisli.. |H!I.-,, S :!(;:.', I'i«, 'J|;(. ) /, sciilii \ ("^1 iliiili ; III, hiliiiiiii \ is( ilniliirc nl' llif liiiilms ; ». siiliiis spinilis ; n, iiii'iliilliili'il |H'ii|ilii'i':il lilnrs Miisiiit! I'lcnii iills in tli>' uiiiiMlinii siiirnlc iiiiil lii'iiit; (ji'^liiiiiiliil 111 III!' iiit;:iiiiiii spinili- (I'lpilii); /«. pi riU;ii-.vipii-i in llif CiliiKliiiii spiiiilc ; 7, liliiml vissci ; 11, liiiiic ; //, iiiiiiiliiiiii!! vcsliliiiliiris ( IJiisH- Mcii ) ; l><\ (I ml IIS (Mrlih^iiis ; il. ( iiiii's iiiiiiilniiiic ; I', piiiiiiiiiiiil ill spirnlis ; li, limiiiiiiiliiiii spiiiilr nirliliir ; /. Iiiiiiiici liMsiliilis; /.■, sriil;! I.Vliipiilli. * 'riii'iT is nil |iiiHir Hull ill lii^ilicr luiiimils the tii'iirniii's ), pp. l!>(i-207), liclifvcs, in (iKn-emciit. with Oniifruwicz, that ':^!'* : i ;-'f ';i \' 1 r)4(! •ri!i': NKKvors svstkm. I)i|)()lar {riilf sii/ini) t lirou-^lioiit life ( l-'iir. :;();!). 'I'lic pcripli- (■ml processes run out to end free without iiiiiiiifold hraiicliiii"- 111 iunoiiir the epitheliiil I'ells of the spinil or;riiii of Corti (Ifet- Fli;. 3()3. — Two liipolar cells I'riini tlic fiaiiKlioii si>inilt' (■dclilciu r»f ii youiiK mimsp. Meth(«l of (iolfji. (After M. voii Leiiliossek. Aiiiit. Hefte. Wiesl)., I{(1. iii[ H. ix. 181W, Taf. xiii, Fig. 1.) /'./•'., i)(ri])lural process; C.K, central axoiie! zius,* Villi (iehueliteii t) inside the dticttis eocliloii' J (Fig. 'M'A). Tlio niediilhited central prolongations or axones of these cells massed together make the iiervus eochlea? (posterior lateral or many of tlic cell bodies of the peripheral auditory neurones are situated in the ventral cochlear nucleus, but this view has not been supported by sub- sequent invest iijafors. * Het/ius. (J. Die Endifjungsweise des Gehiirnerven. Hiol. Tntersuch., Stockholm, n. F.. Rd. iii (1892), S. 2!)-3G. •f van (iciuichten, A. fontribution a I'ctude des ganjrlions ccrcbro- spiniiux. CeUule, Licrrc et Louvaiii. t. vili (181(2), p. 226. X The nervus sacoidi with peripheral distribution in the macula acustica sacculi is a branch of the nervus cochlea'. GUOUl'INU AND CHAINING TOdKTHKIf oP NKUHONKS. 547 cochk'ur root of the norvus acuaticuH). They pass into the con- tral nervous system at the jiuiction of tlic nicdulla with the pons, and enter into rehition with definite masses (mainly the nucleus N. coeidea' veiitralis, and ti\e nnch'us N. eoehhse d(tr- aalis, nueleus tuherculi acustici) of jrray mattiT in which are situated tho cell bodies and dendrites of large numbers of sen- sory neuroiu's of the second order. Tiu' cneidear nerve as it enters the rh()mbencephah>n passes dorsulward ..nd spinalward lateral from the corpus restirormo into the medial side of the large nucleus ni-rvi cochlea' veii- tralis, in which a large number of its fibres terminate (Fig. 305). A buiulle of considerable size, however, can be followed in Weigert-I'al preparations as far as the nucleus nervi cochlciu Fia. 3(i-t. — Siiinil DrRiin of Corti of tlic ductus (•(iclilcaris in transvi'vsc or nulial section. ( Af'tcrd. Kctziiis, from A. Hauhcr's tcxt-liook. ISitS, S. HIS, !•'!«. 743. ) »•(', inciluUatcd distill i)roccs.s('s of liipolar nerve cells in (;anf;lion spir.ile ; /, fonmien iiervosiini in laliiiini I.viniiaui<'uni tiiviuK passifje to a bundle of the cocidear nerve lihres; Ih, tynipanid coveriiiK of lamina basilaris; r.s-, vas spinile; is, internal snpportinj; cells which on the left side ar<' continuous with the eiiithelium of the sulcus spiralis; /*, internal pillar with an inner })asiil cell (/;) next to it : //. external pillar with its external hasal cell, '/ ; /, k!, -i, Dciters" supportinj; Cfdis with i)lialani;eal processes arrivinj; at the sur- face of Corti's orf;au, there attached to tlu" lannna reticularis, /■ ; //, Hensen's sii|)]iortinK cells whi(di dinduish in height toward the ri(;ht side of the figure and art' continuoii.^ with ('. the cells of ('lau
  • i- nalis lateralis, so that in the spinal cord the fasciculus cerebro-spinalis ventralis is an uncrossed bundle, while the fasciculus cerebro - spi- nalis lateralis is in the main a crossed bundle, but con- tains a certain number of uncrossed fibres. tpya, Fl(i. (K4. Sclicmc sliii\vin« the dccussiitii) pynmiiduin ut llif Inner part nf" the uicdiilhi ohliiiiKatii. ( Al'lcr A. van (ic liuclilcii, Aiiatimiic yniniis nirdiilla' oljIonKatii' ; .V. N. ViiKUS ; A7/. N. liypiitrl')ssns. There has been a great deal of discussion during the past few years concei-niiig tiic de- cussation of the i)yrauiitlal fibres. The view {generally held until recently was that all of tlif fibres of the lateral pyramidal tract were crossed fibres wliich termi nated in the ventral horns of tlie same side, and that all of the libies in the ventral tract (direct pyramidal tract) were uncrosst>(l lihres which, however, crossed immediately or shortly before tlieir termi luition by pa.ssing through tlie ventral white commissure to cud •Wii l^^'l ^mmm MHP (iUOUI'INU AND CUAININCJ TOOETllKIJ OF NHl'KOXHS. <»S3 of abtnit I'os whicli k' to the oiigh the e voiili'.il 111 fimicii- t^ido, '/\\- fasi'iculiis iteralis uj,fh the left half of the cervical conl excitiitioii of the motor area in the right coi'tex UhI to move meiit of tlie extremities of the riglit side. In the second i)lace when tliey cut through the left half of the medulla ahov*; the nyr.-.m- idal decussation and again stimulated it, the motor area of the right side, they could produce movements in the left liind le<>-. Again, on cutting through the left half of the cord below the de- cussation at the level of the first cervical nerve, movements in (he right h'g could be produced by electric stimulation of the si'nnoid gyrus. To answer tlie objection tliat instead of innervation of the right foot by homolateral fibrer. tlie <"onnection might be made bv fibres vvlfich crossed twice between th»^ two planes of hemisection tliey made a h)ngitudinal section of tlie medulla and found tliat excitation of the motor area on tlie right side was still followed l)v movements in the right hind foot. While the objection with regard to pressure effects at the level of decu.s.sation must be carefully con sidered, the evidence, 1 think, is, on the whole, .suflicient to justifv the statement that both lieterolateral and homolatei-al fibres exist in the spinal cord, Ix^th of man and animals, ' . the fasciculus cerebro spinalis lateralis. Indeed, it would be surprising, when one thinks of it and considers the nature of the impulses which set out from the cortex, if such a double-sided innei-vation did not exist. The fasciculus cerebro-spinalis lateralis occupies in tlie cer- vical cord the large area in the postero-niedial region of the lateral funiculus. It diminishes rapidly in volume as it descends the cord, being very much smaller in the thoracic than in the cervical, and in the lower lumbar than in the thoracic cord. In the lower part of the cord it comes to lie adjacent to the peripli- ery, while in the cervical and thoracic cord it is separated from the periphery by the medullatod axones which go to make up the fasciculus cerebro-spinalis previously descrihed. The diminution in volume as the cord is traversed depends upon the fact that at the diiferent segments constituent fibres of the bundle turn into the gray matter to end there. The greatest loss, as one would expect, occurs in the region of the cervical and lumbar enlargements in which are situated dendrites and cell bodies of the periplieral motor neurones which govern tlie move- ments of the upper and lower extremities respectively. Helow the lumbar enlargement the number of fibres is small, but a certain number can be traced to the lowermost portions of the sacral cord. The fasciculus cerebro-spinalis ventralis also diminishes in m.i 'tfsii (JH(»riM\(i AM) (lIAlNlNci T<)(}KTnKH oK NKUKONKS. <)s:) voluiiio ;is the conl is desceiulod, iiiiJ in it too tlio loss is greatest ;it tlie levels of the cervicul enhirgenieut, tlie ftiseieulus being entirely exhausted on tlie thoraeie eord. The statement that the libres of the ventral pyramidal tract cross over just before tei'- ininating through the anterior commissure to end in the ven- GyruH foni icul us. ram/rottfiilis ctiimiilir iiifeniii'. Cnvuni se/ifi petliK i- E'... aiinitilrn. ;he cer- of the escends in the d. Ill )eripli- d from ike u}) in /■^M,'dHUatiilhH)iitl<'.i of siiiiiiul nf i;l'>l'iis pallidiis; iiewlioni i>alie. iii\ capiit iiuriei raiidati ; tlio, tlialaiini>: ///, laitaiiieii. .lust medial to the latter is seen tiie tip of the ^lohns i)alliihis (niielens lentifonnis II'. i .Vfter P. Kleelisi),', Andi. f. Anat. n. Physiol., Anat. Abtii., J.eipz., ISSI, Taf. iii, Kij,'. s. i tral horn of the opposite side, has been vigorously combated by von Lenhossek. 'Phis investigator has made a careful study of the sjiinal cord of two human embryos — one thirty-three, the other thirty-five centimetres long. He states that he could never find axones fr in the ventral pyramidal tract entering the ven- tral commissure. He believes that they all run in to terminate in the gray matter of tlie ventral horn of the same side ; that is, that the path from the motor area of the pallium to the ventnd horn cells is throughout direct and uncrossed. Van ) experimentallv pyn. duc(Mi in animals by cortical extirjnition or by section of the l)uiulles at some point in their course; and (4) the application of the metliod of (lolgi. The enibryological method of Fleclisig is especially well adapted for the study of the fibres of the pyramidal tract, inas- much as at birth, or shortly before birth, all the fibres of the spinal cord have received their myelin sheatlis with the excep- tion of these fibres; and in sections stained by Weigert's metliod the positions occupied by the fibres of tlie pyramidal tract stand out clearly and shiirplyas ])ale areas in the set^tion. This metliod has been of particular service in demonstrating the asvmmctrv of the decussation which often occurs in the human cord. It is among the greatest achievements of Fleclisig * that he has traced out with the strictest accuracy the position of the axones of the pyramidal tract and the corresponding bundle of fibres for the innervation of the nuclei of the cerebral nerves, all the way from the cerebral cortex nearly to the termination of the fibres in the groups of cell bodies belonging to the lower motor neurones. The course of the bundles, as outlined Ijv iJiL' embryologiciil method, will be clear if F'igs. G25-0;]l with tlieir legends be consulted The serpuMK e of niedullation in the sensory and motor lihics * Fk'clisij;, 1'. reluT ciiiige Beziehuiij;eii /wisclicii si'diiuliiri-n Di'trciiffa- limu'ii iiml Kntwicki'liiiij^fsvorf^iiiij^eii im 'iienscliliolieii liuekciiiiiiirk. Aicli. (1. Hcilk.. licipz.. I$(l. xiv (IHTJf). S. 4()4-4()!l.— Dio lioitimj^'shahiu'ii im Gchiin iiiid KiU'kciimark des .Monseheii auf (iniiid (■nt\vicki'luiigsj,'i'sc'hiclitli(h( r I'litcrsuchuiifji'ii (iargcstellt. 8vo, Leipzig (IHTd). — ffher " Svstem-Krkiaiik- imgcn " iin Kiickciimark. Arch. d. il(>ilk.. lii'ip/.. IM. xviii (IS77), S. 101 ; 'JHJt; 4(J1; ami Hd. xix (1878). S. W: 4-11: (Viitralbl. i. die iiKHliciiiiscli.ii Wisscust'haften (1877), Nr. ij. — rebcr die ("apsiila interna. Tagchiutt dcr Natiirf")rsclii'r-\'('rsammiuiig. .Miiiiclicii (1877), S. 2^6. — '/aw Anatomic iind I'jitwicki'lungsgi'scliichli' dcr licituiigsliaiincn im (irosshirn dcs Mciischcn. Arcli. f. Anal. ii. IMiysit.l.. Anat. Abtli.. i.cipz. (1881), S. 12-75.— Plan dcs mcnschliclicn (t(4iirns aiif (timiikI cigciicr rntcrsuciuingcn cntworf licipz.. 8v(i. 188;i. — (ichirn und Seclc. Lcijizig (18i)0). — I»ic liocalisatieii i gcistigcn Vorgiinge, Leipzig (I8i(6). CM. f k (;H(>riMN(i AND CIIAINMNM} TOdKTIIKi: OF \Kri{()\KS. »),s7 is (lilTorent as regards the neriplu-nil neuroiu's from that, which concerns the central neurones. Whereas the uxones of the |ierijtlieral motor neurones of the spinal cord and inedulhi (ihlouirata are medullated before tlie axotu's of tlie peripheral sensory neurones, tlieaxoiu'sof the upper motor neurones — that is, those extending from cell IkmHcs in the pallium to the nuclei in tljIvtmfrnyifiiUn hifiriiir. IllSltlll I 'llllSlllll ('.(•<('("»((. Piirs /n>itttili>i fiiiisidit inlirnif. 1 I'usiiruli ri'vrbninphiiih'ii (I'l/nm triiijiordlin ^ miiwriar. ('iiiiild iniiiri rintddti Ciiiml iincli'i ctiiiildti. \'fittn'<'nhin Idfrnilin (('((/•(III (lli/cc/K.s). Fiiriii.r. Ftmtiiithis hd^ildrin me- (liiilifi dnil liiiiiilh' (I, 7Vi(//((((ii(ji. ydsiifiili motdiii nil iitiflios (iirniciim cvrebraltiim. I'ids (i(ri/)i7((/i.s' rdimuliv intrruir. Tifiineittdl riulidtion. I'lii. (i2l>. — Iliiriitiiiital .scctiiiii tlinniKli liriiin ss TIIK NKI! vol's SYSTEM. 11'* J ■«' L two thinls of the jioslci-ior limb of tlu' caijsiih! ; that is, tlio so- <'jilled thahiino-lonliforni portion. Arriving in the internal ('jipsuU', tlicse buniUcs cciisc to hv sc^paratcd bv libri's of aiiitTi'r(Mit, naturo, and bt'conic aggregated in tlio form of a tolerably compact Liimiuii mciinlUiria. ..J n J.dlllhlll UK"- (liillin in. Ldiiiiiiii me- (Julia ris. Fascirnli .. ivrfhro- Kliinaleii in ■ l''/l'(llsi(/'H 1'eijoiintiil rdilidtinn Auflfiix <-aii() to .')I cm. loiifi. ' After 1'. I'"leclisij;, Arch, f. Anat. 11. I'liysiol., Anat. Ahtli.. I-eii)/,.. issl, Taf. iii, Fij;. (i. i /, //. fihihn^ pallidas ; ///, piitanieii ; »/, coiitimiotis with d of Fif;. (Wi. Mufjuifieil fmii' times. fasciculus, which passes first between the nucleus caudtitus and the nucleus lentiformis and farther down between the thaluniiKs and the nucleus lentiformis, to enter the cerebral peduncle. At (ilioriMNd AND CIIAININMJ T(»(JKTII Kli OF NKUUONKS. <»,s',» !il)()iit the junction ol' tlio iiilcruiil cuitsiile with tlio corchral ])0(luiiclc the libres of the })yiiiiiii(liil traot are interwoven witli transverse bands of llbres, wliioh be(3onie niedullated at a period later tlian tliat of the niyelinizalion of tlie pvrainiihd tract. Tills interleaving begins at a level corresj)ondiiig to the dorsal border of the nucleus hyiiothalaniicus (corpus Ijuysi),and extends downward as fur as the posterior and ventral extremity of Luys' body. These transverse fibres rumiiug through the pyramidal tract at this level represent in the main the tibres of the ansa lenticularis. On its way through the internal cajjsule the j)yrani- idal tract is separated from the thalamus by a medial layer of ,y^' Fasciculus Ixisi- liirix mcdidlis. Fiixciculi niotd- rii 11(1 11 uclco.i ... nervorum cerebral ium. Fii.'iciculi cerc- bro-s/iiudlis. Hypothdhimus. v.cierna. y RdiUdtio cnrporin (jenicidatl tncdidli.i. V\(i. (i^H. II(iri/(nitiil scctidii tlinni};li l)iain of liiilx', .'iOto.')! cm. Ikiik, at level of lower third dI" tiisl portion of iiticleiis leiitit'oriiiis. ACter I'. l''leelisiu, Arch. r. .\iiat. u. Physiol., Aiiat. Alilli., l.eip/.., IHHl, Taf. iii. Via- 3.' ", coiitiniiatioii of fasciculus Uasilaris lateralis; edunole, too, the position of the pyramidal tract varies according to the level examined. In tlie : I i Wi) Till-; NKHVOIS SYSTKM. m : lii<,flier rc'gioisof the base of tliu podiiiu-lo (or poa) the pymiiiidal tract occupies the third, fourth, and fifth, reckoned from tiie medial side, wiiiUi lower down it occupies about the nuddle third of the base of the peduncle. At the junction of the cerebnd peduncle with the pons the fibres of the pyraniidul tract split up into several bujidles and help to make up, in larl hiti nil linndlt of llic loi's;!! si rain in of the lia.-is pcdniicnli ; d. nonincdn Haled lilires in diii'siil siralnni ; x, isolated l)iindles of niednllaled lil)res, naliiic nndeterniin((l. >[a.!;nilied four limes. I- smaller uncrossed bundle, consisting of the lateral portion of the pyramis,* passes down as the fasciculus cerebro-spinalis ventralis of the cord. It is of intiircst that liurdach was able to niaki' out tliis jioiiit. Kt%. (JUOriMNC, AM) CIIAININC TOCKTilKIf OF NKl'ItONKS. \y.)l Fleclisig has studied tho decriissutio pyniiiiiilutn iiiid its vuriu- tioiis witli grt'ut euro.* In about fifty per cent, of all wcll-studiud Sulriin mfi)riii\. lioilix vi-ntidlis. /•'((.i'ci('i(/i(.< cfn'hrii siihiiiliH vent ml in. I'l(i. two. — 'ri-imsvcrsc section tlinmj;li tlic s|)iii;il CDnl of a ii('wl)oni Imlic, alxiiit 50 ('111. loll};; level of sixth eervi<'iil nerve. Oold pri'iHinilioii. (.Xl'ter P. FleclisiK. I>ie Leitiiiinsl)aliiu'ii iin (ieliini iind IJiickciiniark, I.eip/... IHTti, Taf. xi.\, Fiji. 1.) cases the distribution of the pyramidal tracts is asymmetrical. TluLs, ill a certain number of instances, all of the fibres go down in the lateral pyramidal tract and there is complete absence of the ventral pyramidal tract on each side. In these cases Flechsig assumes that the decussation is total. f In other cases he finds a * l^'loc'lisig, P. Die lieifungshahni'ii iiii (Joliirn und Hiickeiiinurk des Mensdicii, etc., L. ipz. (1H76). S. 270 c/ my. t From the studies of ex|ieriniental dej^eiieration to be ilcscribed farther (Ml we iKiw know that many of tlie fibres whiidi I'lin down in the lateral |iynimi(hil tract in the spinal eord are uncrossed fibres. It is therefore not improbable, that these cases of ajiparent total decussation are in reality not siicdi, but simply instances in which the uncrossed fibres all j:;() down through the lateral tract; in monkeys this is the normal condition since the monkey [xissesses no vcnti'al pyramidal tract, and yet he is not unprovided witli direct (uncros.sed) pyrauiidal fibres. H ^mWt\ I *i I TlIK NKIfVolS SVS'I'KM. r \U hV m vc'titnil pyramidiil tract on one side, hut iiorio on the other. In other cascH there is ii vciitriil i>yriinii(hil tract on Ixitii sides and in tiiese cases the number of libres in tiie ventral tract of one side as compared with the number of tihres in tiu' lateral tract of the opjjosite side, and again the relation of tin; number of fibres in the ventral tract of one side; to the number of fibres in the ventral tract of the other side, can vary within considerable limita. Flechsig concluded that the fibres arriving from a definite region of the cerebrum through the pyramids into the spinal cord may take either one of two courses, ruunin;51.— Tnmsvcrsf scctidii tlirou^'li tlic spinal cord of a ncwljoni halw. about .'JO cm. loiiK ; level of t'ourth Ininliar nerve, (iold preinuiitioii. (.M'tcr I'. Fleciisif;. Die Leitiin{,'slialinen im (ieliirn nnd Riickeniiiark. Leiiiz isTd Tal'. xix. FiK. 2.) ' ' The area occupied by the pyramidal tract decreases from above downward as the spinal cord is descended, owing to the fact that the medullated axones are ever running in to terminate in the adjacent gray matter apparently in the ventral horns. The fasciculus cerebro-spinalis lateralis, or lateral pyramidal (!l!(iri'IX(i AND CIIAIN'INO T()(JKTIII<;i{ (»!•' N'KriioNKS. «»<.»,*{ triict, lios iilwuys in tlic postoridr Imlf of tlic fiinidulus liiU'nilis. Flt'C'lisip states tlmt tho [Ibrcs never extend further forwunl than an irnM<,'inary stniij^ht line drawn latcralward from tlio (jroiii) of cells known as the colunina intennedin-lateralis. 'I'lii' cnibrvo- loifical method permits one to follow tiie lateral pyninudal tract downward as far as the lower end of the lund)ar enlarj,'e- iiient, or even to the level of the third or fourth saerul nerve. As i('<."inls the relation of the lateral pyramidal tract to the peripiiery of the cord, this varies considerahly at dill'erent levels. Thns, at the level of the third cervical nerve it reaches, as a rule, to the surface of the posterior part of the lateral funiculus, even conung in contact with the pia mater. In the cervical enlarge- ment the lateral ])yramidal tractt is separated from the j)ia mater hy the com])act bundle of the fasciculus cerebelht-spinalis of Flechsig (direct cerebellar tract). From the middle of the tho- racic cord downward the dorsal portion of the lateral pyramidal tract reaches the periphery, although the ventral part of the lat- eral surface of the liundle still remains separated from it. In the lower portion of the spinal cord the lateral pyramidal tract, now grown small, is situated close to the periphery of the cord. The fasciculus cerebro spinalis ventralis,* or direct pyramidal tract, lies, as a rule, on the medial surface of the ventral funicu- lus. The area in cross section is variable. It may extend from the ventral commissure as far ventralward as the ventral margin of the fissura niediana ventralis. In other instances it occupies the dorsal half or the middle third of the medial surface of the ventral funiculus (Flechsig). its kmgitudinal extent in the cord varies much. Sometimes it ceases even at as high a level as the middle of the cervical enlargement. In other cases it extends to tiie upper thoracic or, most commonly, to the mid-thoracic cord. Occasionally it has been followed as far as the intumescentia limibalis. Fmx'TUIcai. Stimilatiov. — A great deal of our knowledge regarding localization of tlie cell bodies of these upper motor neurones in the cerebral cortex has been obtain >d through j)hysio- logical experiments, and especially by means of electrical stimu- lation of the cerebral cortex. f We are indebted especially for this * This was (lcsc'ril)e(l by Charcot as Uw/diwcdu dt- Turc/c. \ It is surprising how .1. IIuf;hliiigs .laeksoii, Ijy means of clinical and tpathological observation and a happy scientific imagination, arrived at very important conclusions concerning localization, wliich have since been in ll 1 t 1 1 k !»!»4 TIIK NKKVOlS SVS'l'KM. iiilvancf to the rcsciin'lu's of Kritsch aiul llitzii;* (1S|()) wjili tli,. j,'iilvaiiu^ c'lirri'iit, ami t'S|n'cially to tlic brilliant rcsulis t)l)iaiii(i| by I'Vrricr t (1ST;>) on faradic excitation of tlic ci'rcbi'al cortex. Tbc ('X|K'riiUfnts (if {'"ritscb anil 1 1 it/.ii; sliowctl that stiniiila- tion of certain n ,_;it)ns only of tlie brain lead to movements of |iarts of tlie body, and tliat between tbe j)la(H> stimulated and I lie part of tlie body set in motion strictly detinite relations exist. 'I'lie idea of a so-(!alled motor cortex tluis arose. 'I'lie experiments of I'\'rrier proved tliat on suitable excitation of tbe surface of tlie cerebrum witli tlie faratlic current move- ments can bo called fortli wliicli po.ssess a delinitely purpo.setiil character. In other words, moveimuitsof the individual parts of the body are evoked which correspond to tlio.se actuallv carried out voluntarily by an individual in the cour.se of his ordiuarv bodily activity. With similar methods l'\>rrier was able to local- ize L'cncrally the principal movements of the face, ai'in, trunk, and le>:; in the monkey. The ijeneral electrical experiments on the cerebral cortex weic carried out with aililitional reliiiements by Ilorslcvand Sciiaefert I V I larijo ])iirt coiiliniic'd hy |iliysii)lo!j;ists ami iiiialomists. 'i'o lu' ('(iiiviiicctl ef tin- woiiili'rfiil foresight (if I ln' writer (iin- lias (inly tucciiiiimrc pn'sciu kimwl- t'lli^t' with \U{\ liypdllit'st's wliicii he inlvaiiccd in tin- t'ollowin:,' uriiclcs: Xdlc:, (in (111' !Miysitiliii;y and I'atliold^y ef Ijanfiuaijc : Ui'iiiarks mi tlniM' Cases of |)is('as(( ef the Ncrveiis System in wiiicli Dcfccl df I'A|ircs.>.ii)ii istlu' most Strikiiitf Symptdm. Med. 'rimes and (in/.., Ijond. (IMOd), i. pp. (irilt tUi2. — On Iidcali/atidii. Med. Tinu's and (in/., liond. (ISdit). i, p. (iUU.— On tile .Vnatdiiiical and i'liysidld-jical Ijdcalizalidii df Mdvcmcnts of liic Uraiii. iiancct, Iidiiil. (IH7;!l, i. pp. S4 ; 1(!2; '2'-\'2. — Oliservations dii the lidealizatidii of Md\(Mneiils in the Cerclinil Ucinisplicrcs, as revealed liy Cases of Cdiiviij- sidii. Cliorca, and .\pliasia. West Uidini; liun. Asyl. Kep., l,diid., vel. iii (1HT3), pp. ITri-l!)"!. — Cases (if Partial Cdiivnlsidii fidm Or^^aiiic Urain Dis- ease, iiearinjj on the l"]xperiments df liitzi^jaiid I'Vrricr. Med. 'rimes and C.az., l.diid. (1875). i. pp. 'uH; ()()(); (i(iO ; ii. j p. '..'(U ; ;i;!(); (IHTtI). i, S. * l''ritseli, (!., and E. liitzi,!;. feher die eleklrisclio Mrrcf^liarkeil drs (Jmssliii'ns. .\rcli. f, .\iial. i'liysicil. n. wissonseli. Med., l,eipz. (187(1), S. ;{()()- :;:w. f Kerrier, 1). Tlie Ldcalizatidii nf Fiinelidii in the IJrain. I'nic. Unv. S(H'., Lond., vol. xxii (187;5-'7i). pji. •J'Jit ',';!','. — The Cnidinan liectnre: V.\ periiiieiits on (he Mrain ef Monkeys. Phil. Tran.-. Koy. Sdc., !,ond., vdl. clw (1870). pp. •i;i;{-48H.— The l''iinetidn .if the Mrain, 'Jd ed., b.ind. (l8St!), p. .VJII, 8vd. \ iidrsley, \'.. and 1']. .\. Schael'er. A Kecdnl nf Mxperiments iijioii I lie l''iinetidns df the Cereliral Corlex. I'liil. Trans. Udy. Sdc., bdiid., v.iI.cIxmx'' uiitl l)y l?t'('Vt)r aiul llorslt v.* At jn't'scnt it wcMild soom us tliouirh tilt' results witli roj^iiril to tlio moiikcv's cortex luv as porfei.'t as till! iiiiiitatidns of tlic iiiL'tliods permit. Siiioo the monkey's cortex, luul cspociiiliy that of tlie oraiig-oiitaii<;, so closely re- sembles that of man, these results are of the iiij^hest importance for the physician and surgeon. Over and over again it lias been possible in human cases to localize with great accuracy the exist- 'ence of an irritative lesion in the motor domain of the cortex, and in many instances surgical interference has been resorted to with success. (H" course the improvements in the techni(pie of brain surgery in recent times have resulted in the mor«' fretiuent resort to opt^rative interfereniie on the brain of human beings, so that it has been possilile in (piite a notable number of instances to y. A Miiiiilc .\iiiilysis (oxpcriini'iilni) of I lio Various Movi'incnls pniiliiciMl l>v Stiiiuilali'ii; in tlic Moiikoy Oiffcr- ent Ht'fridiis of the Corlical CiMitiv for tlic ri)|i(',- Ijinili as Dciint-d l)y Pro- fessor Kcrricr. I'liil. 'I'rniis. Uoy. Soc. Iiond., vol. clxxviii (IHH7) (M.). pp. ir);{-l(J7. — A Hcoord of (lie Hi'siilts ol)tain(d t)y I'lliM'trical Kxcilation of iln' So-calli>d Motor Corti'x and Internal Capsule in t lie ,t> ■%i (juoi'pinh; and chaininc} Toui-yniKR ok neurones, djmj level of the iinterior extremity of tlie small sulcus muikecl x iu their cliagram. Diagram II. Fl(i, (134, — Motor ccrcln-.i! locali/atioii in inoiikcy. (After V. Horslcy ami ('. A. SchiU'lor, I'liil. Tr., Loud., 1888, p. 10, (liugnmi 2.) The trunk area is situated mainly on tlie medial surface of tlie hemisphere, extending for only a short distance over the margin to reach the lateral surface. The general results of their findings are beautifully illustrated in the accompanving diagram (Fig.o;5;5). In addition to their careful study of the lateral surface of the hemisphere, Ilorsloy and Schaefer extended their experiments to the lobulus paracentralis and to the medial surface of the gyrus frontalis superior. To give briefly their results on stimtdating the excitable portion of this area on the medial surface of the hemi- sphere, it may be stated that on applying the electrodes at succes- sive points from before backward they obtained (1) movements of the head ; (•■*) of the forearm and haiul ; (.'?) of the arm at the .shoidder ; (4) of the upper (thoracnc) part of the trunk ; (5) of the lower (pelvic) part of the trunk; (0) of the leg at the hiji ; (7) of the lower leg at the knee; (8) of the foot and toes. It I / ^'\ it. KiOO TIIK NEKVOL'.S SYSTKM. I. L will thus be seen that in the monkey the lieud, arm, trunk uikI U'<;[ are all re))resonte(l to a certain extent upon the facies niediulis cerebri (Fi/:,'. (i;5+). The j)hy.siological results of ablation in the motor areas i>\' the cortex were quite in accord with the findings with regard u> function as determined by electrical excitation. In this con- nection the studies, \ot only of Ilorsley aiul Schaefer, but also of Ferrier and Yeo, of SehiiT, Munk, Lueiani, and others should be consulted. In 1890 the results of an important research were publishcil by Heevor and Ilorsley in which appeared ineir fiudini'-s on electrical excitation of the motor areas of the cortex in theoranir- outang. Since the anthropoid upe is much nearer to man than the bonnet monkey, this study is clinically more applicable than the obseryations which were carried out upon the Macams sini- cus. One remarkable ditTorence between the eiTects of excitation of the cortex of the orang-outang and that of the monkey is the fact that very few "marches" re])roduce. It is evident, there- fore, that the muscular movements of each individual so. -^-A' Hip. :r ^r .•^, •-3/i^H/Jy^r m IP Pc "^ •^ IP Eijes. 'j^^^i^'^K^ •yes LoiA}€T\jaw- SYLVIAN FISSUHL Of- ip. till Fk;. C.\'>. — Ciiiiiparisim of iiiotor rcprcsfiitMtiiiii in tlic liimiict moiikf.v and in tlic oranK-uulanj:. lAI'ti-r ('. E. lUcvcir and V. llurslcv. I'liil. Tv., Lond., lH!li>, 1). 1511, V\ii. 4. ) Subsequently to these fundamental investigations a number of others have been undertaken to localize still more accurately certain of the individual movements in the different areas. Among these the study of the facial area by Beevor and Ilorsley in 1894 may perhaps be singled out. They analyzed minutely the facial area of the bonnet monkey with reference to the facial, lingual, and pharyngeal movements. They undertook in this . study especially a detailed investigation of the so called bilateral representation. This work was very thorough, and th' results Eur 1(102 TIIK NKI{V(H'S SYSTKM. L ■t ' ;' arc onihoilicd in a \(>nMiiiil article, to wlufli tiu' reader wiio is interested can easily refer. 'I'hc report is especially valuable in cotitaininjf a tabular repre- sentation of the series of '* inarches " observed on stimulation of various parts in the monkey's t'ortcx. While a priori there could have been no doubt, after the studies upon the brain of animals, that the human brain also is electrically excitable, the direct proof of this was first established by observations of JJartholow* and Sciamanna.t Victor Horslev established the fact that excitation with a feeble interrupted in- iluced current in the facial area of the cortex of a boy ju'oduced movements in the opposite side of the face ouly when the elec- trodes were applied at points distant from each other and not at interm.'diate iK)ints. Again in 18S8 Keen, of Philadelphia, J localized in the cortex of a man under ana'sthesia the representa- tion for the movements of the wrist, the shoulder, elbow, and face. He extirpated the focal representation of the wrist, and after operation the left hand was found to be paralyzed as re- gards all movements both of the fingers and wrist. 'I'he elbow was weak, but the shoulder and face were entirely uiuifTected. In the same year Lloyd aiul Deaver * also stimulated the cortex faradically and brought further evidence in favor of the view that the integration of movement representation is much more nuirked in man than it is in the monkey or even in the anthro- poid ape. It was made out that considerable areas did not ap- pear excitable at all to the strength of current employed, definite movements corresponding to the epile})tic seizures from which the individual had suffered being elicited on stimulation of cotn- * lUrtlioIow. H. FApcrimPiitiil Invest ipU ions into the Functions of the Hiiiiian Hniiii. Anu'r. Jour. Mod. Sc, f'liila., ii. s.. vol. Ixvii (1874). i)p. ;i()5- liV.i. f Sciamantm. K. GM avvorsari dciii' lociiiizzazioiii ciTobnili. Ardi. di psicliiat.. etc.. Torino, vol. iii (188'2). pp. '.20!)-218. X Kooti, \V. \V. 'i'hrco Successful Cases of Cerebral .Surgery, including (1) the Ueniovul of a Large hUracranial l<'ibroina; (2) l*-xsectioii of Damaged lirain Tissue: and (:?) Kxsectioii of the Cerebral Centre for the Left Hand; with Heniarks on the (Jeneral Techni(|Ue of such Operations. Anier. .lour. Med. Sc. Phila,. n. s.. vol. xcvi (1888), p. :i2i>: 452. « Lloyd. J. IL. and .1. K. Deaver. A Case of Focal Epilepsy successfully treated by Trephining and F^xcision of the Motor Centres. Auier. .lour, Med. Sc, IMiila., n. s., vol. xcvi (1888). pp. 477-487. (iHoriMXd ANM) ("IIAININMS TiKJKTIIKIJ oF N'KrWONKS. loo'J fmnitivo'y restricted iiri'iis. Siiniliir ohservutiods were iiiude by Nuncrcde* with Morris .1. Lewis. For tiie lociiliziitioii of function in the oortox, thoroforc, cloc- trioid excitation has hcoii of immense valne. Hnt no less fruitful results have been obtained by the same method with re<;ard to the localization of functioti in the bundles of fibres which pass through the internal capsule. Here again our most important knowledge has beei\ derived from the experimi-nts of Heevor and llorsley.f N'aluable results by the method of excitation have also been obtained by Burdou Sanderson J and Franck and l'itres.» In experiments upon the internal capsule it is essential that the exact anatomical location of the fibres stimulated be men- tioned, for in (litTerent horizontal planes the motor fibres occujiy entirely dilferent positions. The term capsula interna is a bad one, but has been so uniformly employed that it seems necessary, at least for the present, to retain it. Hy it is indicated tlie white fibres bounding the nucleus lentiformis on is medial side. The term is, however, more loosely employed ami is made to include all the descending and ascending fibres of the corona radiata, which pass between the basal ganglia — between the nucleus caudatus and the optic thalamus on the medial side and the nucleus lentiformis on the lateral side. Above, the capsula interna is directly continuous with the corona radi i, while be- low it is directly continuous witli the base of the cerebral pe- duncle. I'he upper and lower limits of the internal capsule must, therefore, bi arbitrarily defined. The ujjper level would * Nuncredo, C B. Two Siiccossful Cases of Brain Stirpory. Med. News, I'liila., vol. liii (1888). pp. r)84-r)88. f Bcovor, (". H., imil Victor lidrsloy. An Kxpcriineiital Invest ipit ion into tlie Arrangement of the Kxcital)le Fitircs ot the Internal L'apsnle of tlie Bonnet Monkey (Macacns sinitMis). IMiil. Trans. Hoy. Soc. (181(0), Lond., vol. clxxxi (18!M) (B). pp. 4!)-88; A Beeonl of the itesnlts obtained liy Kleetrieal Kxeitation of the So-called MotorCortex and internal Capsule in tlieOrang- < >utang (Sinna satyrus). Phil. Trans. Roy. Soc. (189(t), vol. clxxxi (B.), Lond. (18!n). pp. l'29-lo8. I Sanderson..!. B. Note on the Kxeitation of the .Surface of the Cerebral Hemispheres by Induced Currents. Proc. Hoy. Soc. Lond., vol. xxii(187;{-'74). pp. :U)8-;5T(). * Franck, F. Le(;ons sur les fonctions niot rices du cerveau (reactions vohuitaires et organicjues) et sur I'epilepsie cercbrale. bvo. Par. (1887), pp. 21 -'-"3. i % 1004 TllH NKllVUL'S .SVSTKM. corrospond to a pliitic rcstiiii? upon tho upper surfiiccs of the oiiiidatc !Ui(l Iciiticiiliir nuclei; the lower level is usiiallv iletiiiod as the re<,qoii (correspond iii<^ to tiie posterior and inferior linut of the fibres of the ansa Icntieularis which pass tiirough the internul capsule at its junction with tlio cerebral peduncle. The capstda interna has been compared not inaptly to a mass of libre bumlles arranged like the rays of a fan, the handle cor- responding to the base o^ the cerebral peduncle, the sides of the fan corresponding to the antero- ventral aiul postero-dorsal bor- ders of the internal capsule, where it joins tiie corona radiata. This appearance is well shown in a sagittal section passing through the cerebrum (l^'ig. 03(1). Til. C.a.c. X.l. All. Fui. (53fi. — Siifjittal scctiun tlirdURli tlic liniiii (if tlio monkey. illiistnitiiiK tlir iiit( riiiil capsiiU". (Al'tcrC. K. Hccvor iiiid V. Horsliy. IMiil.Tr., Lmid., lSiH». pi. xi. FIk. 15. I .1.(1., iiiitc rior or ascciiiliuf; tihrcs of tlic pais frontalis of capsule; //, liori/.oiital fibres of tlie same : s.d., superi ; Til. tlialauuis; ('.it.c, comniissura anterior cerebri. In horizonttd section tlio aj)pearance of the capsule Viirio^ euorinonsly at diU'ereut levels, as is shown by the accompanying figure (Fig. G37). At the horizontal level of the capsule most (JU()riMN(} ASM) CIIAININd T(«iKTIIKI{ oK NKl'HoNKS. loon rr("(|iU'Mtly described (tliiil is, ii iKtri/.oiital section wliii-li atrikt's tho vi'iitnil end of the genu corporis callosi, tiie piilviimr, mid llie ib A-.( .1.11. fiiru's living liiiost H. I''l(i. (W7. — Position of tilircsat varimis levels ol' liic ciiiisiilu iiitiTiia ol" tlic iiioiikcy. (.M'lcrC. K. lici'voraiid V. llorsliy, I'iiil Tr., Loiul., IsiHt, pi. v, \'\k. l.i polus occipitalis, Fij;. (ilJH), one sees tiiat it can be divided, us Charcot suggested, into an anterior limb and a posterior limb, which meet at an obli(pie angle to- t'orni the so-called genu capsulii' interna'. The anterior limb is knowji as tin; [lars frontalis capsula' interna'., while the posterior limb is designated the pars occipitalis capsula' internst;. The pars frontalis (sometimes km)wn as the lentifornu)- striate portion) is snudler than the pars occipitalis and consists at this level almost exclusively of llbres running nearly horizon- luUy and made up in the main of axones running corticahvard from the thalamus. As tho genu is approached the fibres assume a more vertical direction. The pars occipitalis can bo further subdivided into a thalamo- lenticuliform portion (that situated between the thalamus and the nucleus leutiforniis) and a retro-lentiforjn portion, namely, that portion situated lateral to the thalamus, but behind the posterior extremity of the nucleus lentiformis. The fibres which pass through the genu capsuhe interna' are iu»t located in the same antero-postcrior position in all horizontal Itlanes, since the position of tlie genu alters; in the more inferior horizontal plaiu's it is situated far more posteriorly than in planes higher up. In the same way the pars frontalis capsuhv interna; is shorter in inferior jilanes than in sujjerior planes, 'i'hc impor- tance of recognizing these ditTerences in position at difTcrcnt levels can not be too much emphasized ; much of the confusion in pathological literature with regard to the internal capsule is due to the fact that clinicians and pathological anatomists have j)aid if lo(i<; TlIK NKItVol'S SYSTKM. Hi i : J I 1 ite t'lci. i'al ht'inisplicrr lul at II ilistaiici' III' )(l niiii. Im'Iiiw its siiprrinr luirdcr; imtiinil si/r. lAI'Irr .1. Dcjcrinc. Aimtoinic dcs (Viitrcs NtTVciix, raris. IMII.I, \<. lOH, KIk. ~>tl. ) .(iV, cliiiistriiiii ; (', ciiiK'iis; ('A, liippocainiMis irnriiii aiiiiiiiiiiis> ; Ccii), kciiii nirpiii'is calliisi ; Cc, capsiila rxtcrna ; <'/), k<'Iiu rapsiilii' iiilcriui- ; Cinii, linri/ontJil ImiikIIi' of tlu- ciiiKiiliiiii ; i'iiKiii)), iKistrriiir ImiikIIc of tlir ciiiKiiliiiii ; ('ii>, pars on-ipi- tJtlis capsiihi- iiitmia- ; Cirl, ri-troU-iitiiiilar piirtion nl' iiitmial capHiiU-; rm, Hiilciis ciiiK'nIi : Co, rnitniiii sciiiinvalc ; coyt, niininissiini posterior ccrcliri ; f'Kt; Kynis sulwalliisiis ; ; \t.a. imtameu Hif nucleus lentifonnisi ; O,, Oj, ^yri occipitales; nn. sulcus occipitalis anterior of Wer- ni<'Ue; Oh', fasciculus occipito-frontalis ; ni, sulcus iuteroccipitalis ; O/*, /'a. pai-s opercularis nyrns t'rontalis infcrioris ; O/ih', liolandic operculum ; I'nTIi, pednnculus anterior tlialami ; po, tissura parietii-occipitalis ; I'lil. pulvinar; ire/, cuneo-limhic fold ; n/ili). posterior parieto-limhic fold ; liTli. ndiatio occipito-llialamica (ii-iitioleti ; N yv. ninnis posterior lissura- cerehri latenilis Sylvii ; S(r), ramus asceiidens ; .ice, sinus corporis callosi ; >y;c, siihstantia ftrisea centralis; .S/c, suhependymal ^niy matter; T,, sryrns temporalis superior; 7'j. Kyrus temporalis mediiis; /,, sulcus teniponilis superior; '/'<(/(, Uipetum ; tf<; ta-nia tccta ; Tija, anterior pillar of the fornix ; Tij I', ventriculus lateralis; 7Vi. thalauuis ; Tp, Kyrus temporalis tninsversns ; //<. sulcus tem- poralis tr.msversus ; 1'^, vt'iitriculus tertius ; I', stripe of Vicci d'A/.yr ; I.I, fasciculus thalamo-mammiliaris \'ii(| d'A/.yri ; \'J', cornu antvrius vontriculi lateralis; I'sl, cavum septi pellucidi ; Xi\ /.oiiu reticularis. ill' un i t if (iKOl'I'lNCl AND CII.MNINO TodKTll Kit (»!•' NKrUoNKS. Kio"; I 'Mil Mule, if !iiiy,ntl('nti(iM lo tlic variiitioiH in I lie Htnicliirr of I lie (■ti|miil(> at (lillVrt'iil liori/oiilal levels. In every eiiHe in whielMii iiiitopsy a eirciiiiiserilted lesion of I lie iiiteriiiil eapsiile is found (lie |iallioloj^isl, should take care lo deserilie ueeiinilcly the exiiet loeali/ation of tlie lesion with i'e;^ai'd tu |>laneH tiikeii in the three dinieiisioiiH of spaiH*. (hi iht^ whole it may lu* said that the iihres iiussin;^ llirou^di I he internal capsule correspond very well in position to the ^yri to which or from which they ladiiitc, those fartlu'st forward lieiii;.; connected with the frontal lohe, those in the middle with the central iiyv'u while those more posteriorly situated run to or from the temporal and occipital ;,'yri. Iteovor and llorsley found that the pars frontalis capsiihi' interna' is for the most part entirely tiiiexcituhle, or rather that electrical excitation applied to it leads to no motor response. The Iihres which on stimulation call forth deiinite movements iitiform i>ortion of tli(> iiiterniil (;a|)sul(s iloit is, the f^M'iui ami the anterior two thirds of the pars occipitalirt cnpsiila' interna'. l'"rom hefore hu(;kward in the internal capsiih^ the arran<^enient of tins Iihres is as follows: l-'arthest forward stimiilalion emises movements of the eyes. .\ litlj/e farther hack tlio lihros for the openinnt in the capsnh' is therefore : liiivc scon, wlu'ii sMi(lyiii;f tlio uxoiics of tliciKU'pliiilo-tflciicc- ])liiilic scjisorv luMiroiK's, this r('<,noii of tlic ciipsulc is tliat in N'liicli iiiiiiiy of tlicsc iixoiios arc sitii;ittMl. 'I'lic study of the i»tonml ciipsulc of I lie oranf^-ontiiii" l>v tiic tnotlioti of cloctrioal I'xcitiition yielded, aeeonliiifir to Heevor ami llorsley, results very similar to those obtained with the boiuict monkey. The Idealization is ("pitoinized in the following tat)l(' : MOVKMKNT. From M. M. IIIHX. 2 5 ;{ 5 4 7 4 6 5 8 5 !) 4 10 (i S , , 111 10 111 »' 10 Kycs turn lo opiiosiic siilc | l\V('li(ls cliisiii):; (l)liiil\in;,') Hclrai'tioii of uiif^lo of uioulli to (ippositc sido Toil;;!!!' tlaltfiuMl ami lip dirocti'd to oj>|)osil(' side . . I'Mfxion of thuinli Flexion of tiniicrs I'Mcxion of wrist I'Mcxioii of clliow AlidiH'l ioi) of siioiiidcr Aii motor cerebral nerves uiuler the inilnenccof the pallium are not, strictly speaking, included in the term " i)yramidal fibres." The " pyramidal tract" i)roper consists of the fibres which go through the pyramids of the medulla and form the fasciculi cero- bro-spinales lateralesand the fasciculi cerebro-spinales ventralesof the spinal cord ; tlnit is to say, the fibres of the pyramidal tract, strictly speaking, innervate maiidy the lower motor neurones by means of which 'he movements of the upper iind lower extremity are executed. .Many writers, however, especially English and American neurologists, include the fibres going to the lower motor neurones of the cerebral nerves, as well as those going to the lower motor neurones of the spinal cord, under the term j)yram- idal tract. This is a matter of nomenclature and of but little significance. Th(> main point for the student to grasp is that '4' % (iltoriMNd AND ('IIAININ(J TU(il<:TIIKU OK NKUUONKS. U){)\) l)()t,li sets of lilircs lijivt> u similiir fmii'tioii t.o throw tin- Iovvcm* iiiolor nciiroiif.s iiiidt'i- tlic iiilliit'iicf of the itiilliiiiii. F3 oj en . Ml, Kin. 7.) I'ilCI' of il V. Mors- Ffoni the fact that in the cortex und in tho intcriiiil (lapHule the l)iiii(il('.s of Hl)n^s arc arranj^cd in groups (M)rr('H])on(liiig to tlie (iilTercnt niovonicnts, and from tho fact that in tlici spina! oord lil)r('s whii'h run for the ioiifrcst distance tciiid to he more peripli- crally situated than thos(* wlii(!h run for shorter distanci^s, it is not surprisiiif? to learn that in the fascicudiis eerebro-spinalis hit- cralis of the spinal cord there is a definite firoupinj^ of the (ihres correspond inrpcrtli('il(' licsliiniiitcii iiiotoriscliini IJaliiieu iiii Kiicl E Fle.iiiin ill hi ji joint i homolat- eral). t'le.rion in hil>. knee, and ankle {homolat- eral). I l''i(i. (MO. — Kxpi'vinu'iitiil stiiniilation of fivslily cut suhsluiitiii iill)!i (if . LevelofrX. K. Level of (' VIIL Stimulation at />' aniU,', uiove- iiieiit.sof trunk I liojuolateral 1 ; at ;», tliitjli ' skin of aliilouieu : at «, lioniolat- eral sef^niental trunk nuiscles + extension of lioinolatenil foreleg i plantar Itexion and ailduction of toes); at k. no muscular eontraction. mj-'X^atPSitKC i 1012 TIIK NKUVOUS SYSTKM. ■)i whioh passes down in the ventral column of the cord on the same side without decussation.* lie asserted that these tracts degen- erated oidy in a descending direction from the side of the lesimi altiu)ugh he recognized that above a given lesion there were numv fibres which degenerated in an ascending direction. 'J'iirck sug- gested that the cause of the secondary degeneration was probablv the interrujjtion of conduction, and inclined to the view that the coTuluction direction could be concluded from the direction as- sumed by tlie degeneration in a given case. This preliminary knowledge of secondary degenerations was much expanded by the investigations of Houchard,! Charcot,* Pierret,* Xotluiagel,|| von Monakow, and others. It has l)eeti possible in a large number of human cases to follow the second- ary degeneration not only of the whole pyramidal tract, but also of the separate portions of this tract, to their destination. A good example of the secondary degeneration of the pyramidal tract after a cerebral lueniorrhage in the region of the internal capsule is illustrated in the accomj)anying sections (Figs. 041). I''rom what has been said of localization, it is obvious that lesions of the cerebral cortex will be likely to cause only partial sec- ondary degeneration of the pyramidal tract, since, in order to lead to complete degeneration of the tract, an enormous area of cortex would have to be involved, and, as a matter of fact, hu'morrhages and other lesions implicating the cortex of tiic pallium and centrum ovale are not sufficiently large to lead to destruction of the cell bodies or axones of all the neurones ex- tending between the pallium and the groups of lower motor neurones. Tiifortunately for human beings, however, the nu)st frequent place in which the pyramidal tract suffers injury is the internal ca])sule. Here the fibres are closely ])ressed together * Tlirck designated this the Iluhen- Vorderstranghnhn. + noiR'lianl. ('. Dos (lop'iu'Tatioiis sccondiiires dc la moelle ('piniore. Arch, gi'ii. do iiicd.. Par. (1866^. i. pp. 272: 441 ; r)(it : 578; ii. 27.'?. X Clmrcot, .1. M. Lemons sur Ics iiialadios du systi'me iioi'vciix fiiitos h 1m SalpotriiMv. 8v(.. I'aris (1872-"7;}). * I'it'iTcl. Coiisiduratioiis anatomiciiies ot patiiologiques sur Ic faisecaii postorioiir do la moollo opiniorc. Aroli. do physiol. iionn. et imth., Par., t, v (187;]). pp. r):i4-.')4r.. II Notluiagel. H. ExporimoTitolle Uiitorsucluiiigon uobcr die Ftiiictioiicii dos Gehirn.s. Arch. f. path. Anat.. etc., Perl., 15d. Ivii (187:3), pp. 184-314; Hd. l.x (1874). S. 12!»-14!). i * I L Fl(i. (ill. — DcKi'iit'iMliiPii. fiillowiii}; lin'iiiDrrliiitjc of six iiioiith--' d iiuclciis latt'iMlis tlialanii anil in the l('iiticiii(>-ii|ili<' |iiirliiiii iil' || iii'utidii, ill tli( If CilpSlllil interna. i .M'lrr ('. voii Mmiakow, ( JcliiriipallioldKit', Wicii, ls!i7, |'j.r 171-17.').) A. (»lili(|nc liiiiizonlal section tiiroUKli the aiitei-iiir part of iTk imeleiis li.v|iotlialaiiiiens. corpus liiiysi ; //, eyslic nodule iillcd will transt'ornied lil 1 ; //i, /■', pericystic sol'teiiiii;; <■/, caiisiila interna ; />, secondary defeneration in the capsiila interna, dotted red ; llw |iyramida. tract is interrupted ami totally dejjenerated ; ,/. insula; /,''.' niicleii.s iiy))ollialainicus : /'((/, iieduncnlns cerehri ; //, traetus opticus; /,(, nucleus leiitllorniis corpus striatum ; Inl, nucleus lateralis tlialai 111 ; iriil. nucleus ventralis thalaini ; hue, lamina mediillaris. H, (', I), t'roiilo-liori- zonlal sections i plane of Meyiiert i throiinh the hrain stem of the same ISC ; |{, level of the coUicillus sil]ierior and of the pedunculiis cerehri ; (' liddle of pons ; 1). medulla ohloii<;at;i T A(lh iilicdiictus cereh le (IcL'eiu a. I ///. uervils rated pyramidal tract iiotoriiis ; /// A'. nervi ociilo-motorii ; si'h. lemniscus medialis ; ///,, fasciculus loUKit medialis ; ISA, hracliium conjunctivum ; i!r.\, nucleus iidinalis >rachium poiitis; /•(•(/, pcdun- (T, corpus cuius cerehri ; iii/r, pyramidal tract def;enerateil on the rifjht sid restitorme ; I'. (/»/'v/. ti-aetiis spinalis uervi trinemini. K. Dcjieneratcd til in the spinal cord of the same case ; 1 :i, pars cervicalis ; t -S, pars tlioracalis • !t- 13, jiai-s lumho-sacralis ; /»//)■, fascirulus cerehro-spinalis venlralis; jti/ni] fa.sciciiliis cerehro-spiiiiilis lateralis. OROUIMNa AND CIIATNINO TOOETHKR OK NEURONKS. l()i;} £ H V!l>'a l>!ir vyr ^^••-■^pSI vyr pur PVa i>y>;, pyr VUl-a py pyra ptir left. I right, pyr [014 TIIK NKUVOl'S SYSTKM. h'} i into a compact bundle, and a tol('ral)ly cin'tunpfribod lesion will suttico to lead to complete interruption of all tlu! descendini' motor axones. 'I'iiis rej^ion of tlie internal capsule is supplied in the main by tlio HO-callud lenticiulo-striate artery of Duret, and in by far the greater proportioji of cases of Ineinorrliagp this artery is involved. So fre(piently does liaMnorrhage take place at this site that this artery has been designated by Charcot as the "artery of cerebral lia-morrhage." This explains why it is that in the nnijority of instances of cerebral haunorrhage there results total hemiplegia of the opposite side of the body. At autopsy the motor tract below the lesion will be found degener- ated, aiul the area of degeneration can be distinctly nuide out in the cerebral peduncle, in the pons, in the medulla, and in the spinal cord as far as the lowest level to which the fasciculi core- bro-spinales penetrate. If an autopsy be made before too long a period has elapsed, the area correspomling to the ])osition (K N i;i HON I'.S (roNTI N I i:ii). Kilii'cs frum llic |ialliiiMi lo (lie iiiolur nuclei uf tin rdiriil nerves Stmlii^t of lloclie unci iilliers -Itesnils (if exi ir|iiil ion iif icieuli/eil nrrn-i of t|i(. eorlox — Si;,'nincani'e of uncrossed fibres of tlu> pynimidai trael — Inler- cuiiition of ilemlriixones lielween upper motor neurones iinil lower tnolor neurones — '{'he centrifutriil corlico-inuscular conduction path — Clinical symptoms foilowiu),' lesions of dilTercnt portions of the path. 2. Those the Axones of which run to the Motor Nuclei of the Cerebral Nerves. 'rill'; sillily of the (Icjjt'iH'fiiUMl (losct'iiiliiifj; motor iixoiics in luiiiiiiii hciiiLTs by niciitis of the incthod of Miifclii lius in rocciil years thrown a llootl of new liijlit upon llic (listril)iition uf tlicsc nxotios. As :i siiiti iisiiully (li'sijfiialcil as I lie iiiolur iin'u, in u Hi'ctioii of tho ccrtfbrul |m-(1iiii('Io wliii'li lias always Itt cm l»clifV(Ml to he an area tlirixij^'li wliirli scn- sory tilirt's pass ii|i\var(l iiilo tlic ('('icldMiin, tl»';,'<'n('rali(»n liiid (UHMirrcii in a «'»'iitril'ii;,'al direction. Iloclic I'oIIowimI the df^xcn- onition from the hiisn of the ccrfbrul peduncle and downwurd. 'riiu pyramidal irart proper (for llie upper iiiul lower extremities) eorrespoiidetl closely to I lit! descriptions usually ;,Mven of it. 'I'liiiH no libres were ;,'iveii oil' from it to the nuclei of the iiervi oenlo-motorii, althoii^'h a jfreiit niimlier were followed from it to tlni nnch'iis nervi fa<'ialis iind to tlio nneleuw nervi liypoj^lossi. Ilttehe found lilires ;,'rn of the same siih;, but some of them pass throu<(h tlu! ventral white commissure to enter the ventral horn of the opposite «ide. Iloche also as.serts that the fibres from the ventral jiyramidal tract (fasciculus cerebro-spinalis ventralis) run in \o terminate in the gray matter of the ventral horns of l)oth sides, but mainly in the ventral born of the opposite side of the cord, llociie's find- ing, that libres of upper motor neurones run to the cerebral motor nuclei of both sides, brings these nuclei closely into accord with the motor nuclei of the spinal cord. Si ill more interesting, however, than thes(! double relations of the pyramidal tract to the cerebral motor nuclei are the observa- tions of Ilotdie with regard to another descending motor tract. In his first case, especially, he was able to jirove that the nucleus nervi facialis and the nucleus nervi hypoglossi receive mediillated axones from tlie cerebrum by a path entirely separate from the jiyramidal tract, which descends through what we have been accustomed to consider as an almost purely sensory region — namely, that of the medial lemiusous. Coming out of the lem- niscus niedialis in the pons and extending between it and the I ■ 4 1 h HllS TllK NKIIVOUS SYSTEM. . t 111 'I: m ih.^_ n 'N (il{OUPIX<; .VND niAININO TOOKTIIKR OK NFA'UOXPX joH) •- St o _ 1; ^ a b ;; ^ at) il V t.~3 D ^ ' * •-3 J2 -■■- I- \o V \\m ''1!' \'.\ i ,^ \ — t I m^ fi 1020 TIIK NERVOUS SYSTEM. nucleus nervi facialis of the same and of the opposite side could be made out a number of degenerated fibres. In the same way coming out from the stratum interolivare lemnisci of one side could be seen a number of degenerated fibres extending from it to the nucleus nervi hypoglossi of the same side and throufrh the raphe of the nucleus nervi hy])oglossi of the op])osite side ( Fig. 043). That these fibres are entirely distinct from the majority of tht; fibres of the lemniscus medialis is })roved not oidy by Lhe fact thai they degenerate in a descending direction, but also by the fact that higher up in the nervous system they are entirely separated from the rest of the fibres of the lemniscus medialis. I'hus in the upi)ermost planes of the cerebral peduncle these fibres do not lie in the region of the lemniscus at all ; they are situated in the base of the peduncle in the immediate neighborhood of the fibres of the pyramidal tract, but are placed lateral to them. These fibres in reality appear to come out of the internal capsule, whence they go into the base of the cerebral {)eduucle, occupying a position just lateral to the fibres of the pyramidal tract. In the pons, however, they become somewhat sejiarated from the fibres of the pyramidal tract and become displaced into tli(> region of the lemniscus medialis, running downward in tiiis bundle for a considerable distance. It is interesting to note tliat this descending centrifugal bundle of the medial lemniscus had been made out many times before, though its significance had not been properly valued. Thus it had long been known from the researches of Flechsig and von liechterew that a certain number of the fibres from the medial lemniscus become nuidul- lated at a much later period than do the majority of its fibres. Von Bechterew had even given this bundle a special name.* lloche has studied the position of the fibres in the brain of the newborn bal)e, when they are easily distinguishable owing to the fact that they are non-niedullated and appear as pale areas (Fig. (M4). It is especially interesting that in Hoche's two cases the most medial parts of the base of the cerebral peduncle (Flech- sig's frontal cerebro-corticopontal path) were entirely free from * von Ik'ciiterew designaliHl it the accessorische Schleife. Si^hli^siii^'cr calls it the latentlc jiontixe lii'ivdel. It is not, howi'vor, idontical willi llii' temporal coroiiro-corticoiHintal ]iath of Flcclisig; for in the liaso of llic peduncle Iloclie's fii)ivs lie lictweon the temporal cerehro-corticopoiital piilli of Flechsig and the til)res (jf the pyramidal tract. HSSH?^*^ (HiOL'PING AM) CIIAININO TOGKTIIER OF NEURONES. 1()21 (.k'gt'iiL'ratioii ; aiul lliat also tlio most latonil portions of the base of the peduncle (Flechsig's temporal cerebro-oorticopontal path, Biindel von der Schleifc Ins zum Fuss) were also entirely free from secondary degeneration. r ' Fiti. tut. — Non-nu'dulliitcd (ilircs in llic Ifiimisciis at l)irtli coiTcsixiiKliiif; to tlui cciitririiKal IiuikIIcs oI' tlic Iriiiiiiscus. i.M'tcvA. n(i('l\f, Anli. I', rsydiiiit., Hcrl.. |{<1. XXX. ISitS, Till', iv, Fius. ;.'l to :iH. i A. Level u\' tlie colliculiis in- ferior. H. Level of superior part of pons. ('. Level of iierviis tri^ieiiiiiiiis. I). Level (tf .spinal extremity of nucleus nervi faeialis. H. Level of nervus vajius. In the most medial part of the podunclo, Fleclisig atul otlicrs have located the path from the pallium to the nuflei of the tuotor cerebral nerves, while by Spitzka it was ))laced in the lateral part of the pes, in the so-called bundle from the leniniscns to the pes. \| 1-^ ;. 1022 TIIH NERVOUS SYSTEM. J' ^ It soems probable, therefore, on comparing iloclie's researclies witli those of other investigators, tliat tiie nuclei of tlie motor cerebral nerves can be thrown under the iiitiuence of the pallium bv jueuiis of fibres which run in two entirely ditferent paths — (]) apatii situ- ated in the pes medial to the pyramidal tract, and (2) a path in tlnj ])es lateral from the pyramidal tract. That d liferent motor paths destined for the cerebral motor nuclei nun nossibly exist is of tlm highest interest in connection with the pu/,/. ling clinical j)rol)l(!ins met with in the domain of distribution of the cerebral motor nerves. We may hope that further investigations with the Marclii method of secondary degeneration after cerebral lesions will clear up aiuitomically these clinical differences, especially with regard to paralyses of the face and tongue which have so long puzzled us. In one of Iloche's cases there was degeneration of an abnoi- mally placed bundle of fibres of the pyramidal tract, which evi- dently corresponds to the abnormal bundle described by Pick,* Heard, f of Pittsburg, and others. It would seem that in a few instances a bundle leaves the pyramidal tract of one side, under- goes premature decussation in the raphe, and takes an abnormal course through the medulla oblongata, fusing finally again with the fasciculus cerebro-spinalis lateralis below the level of the gen- eral pyramidal decussation. One of the most fruitful of all the modes of investigation for the determination of the course of the fibres of the pyrauiiilal tract, especially of individual portions of this tract, is that of ex- tirpation of the whole, or, more particularly, of limited areas of the motor cortex, with subsequent study of the nervous system for secondary degenerations. The earlier studies of von Guddeu,]; von Monakow,* Franck and Pitres,|| and Moeli ^ were carried I * Pick, A. Ueber ein abnorines Fuserbiiudol in der Mcnschlioht'ii Me- diillfi ohioiiffiita. Arcli. f. I'syohijil. u. Nervenkraiikh.. IM. xxi (l.,"!:i!)). f Ilciird, .1. I). Ueber !il)n(>rme Nervetibiiiidel in der Medulla otjloiignl.i des Meiisclieu. Arl). a. d. Inst. f. Anat. u. Physiol, d. ('mitral iiervensyst. an (1. Wicn. Univ., Leipz., u. Wien (1894), II. ii, S. H<5-!)(). X von Gudden. Cor.-Bl. f. seliweiz. Acr/te (1H72), No. 4. * Experiinentelle Heitriif^e zur Keniitniss der Pyramiden- uiid Schleil'cn- bahn. Cor.-Bl. f. .schweiz. Aerzto, Basel, IM. xvi (1884), S. I'J!» ; ir,7. I Fraiit'k, Francois, el A. Pitr(>s. Des ilejifeiienitions seeondaires dc In nioelle epiniere conseeutivc^ a I'ablation du gyrus signioide cliez le I'liien. Gaz. nied. de Par., 0. s., t. ii (1880), pp. 153-154. ^ Moeli, ('. Uel)er sekundilre Degeneration. ArcIi. f. Psyclnat. n. Nervenkr., lid. xiv (1883), S. 173. GROUPING AND CHAINING TfKJETIIKH OF NEUKONKS. 1023 out witli the aid either of the carmine method or the method of Woigert, but the newer studies liave been much more exact owing to tlie possibility of greater accuracy afforded by the delicate method of Marchi. With tliis method Marchi and Algeri,* Mura- toff,f Mellus,J Langleyand Sherrington,'* and Sherrington|| have obtained important results. Of these experiments, those which have been carried out upon monkeys are of course most valuable, since they yield conclusions more applicable to man. In general it may be said that they have shown that the course outlined for the fibres of the pyram- idal tract by the embryological method and by the method of electrical excitation is correct. The experiments have also cleared up the puzzling findings in human cases, in which after unilateral cerebral lesion degenerations in both lateral pyramidal tracts of the spinal cord were observed, since they prove conclusively that, after extirpation even of minute areas of the cerebral cortex in the motor region, fibres of the pyramidal tract degenerate, not only in the lateral pyramidal tract of the opposite side of the spinal cord, but also in the lateral pyramidal tract of the same side of the cord. P^ach cerebral hemisphere in the monkey is connected with the ventral horns of both sides of the spinal cord. The explanation of the appearance of degenerated fibres in both lateral pyramidal tracts has been attempted by Sherrington and by Melius. Sherrington's earlier researches led him to be- lieve that there was a total crossing of the fibres of the pyramidal * Mart'lii, V., e s fr4.*)). L Fui. riy i ^flll•llnl.^< Khiinis], sliowiiii; (•(irticMl area cxlii'iiatcd. //, lialliix ; 7'. tlimnli; /■', I'acial. Hcinj; IIk' upper hnnlcr nl' lacial an iiupim the aiUt ri(ir iintral k.v1''ii^. tlic iiKivciiiciil represented lieiiiK eliisme (if llie «il)p(isile eye and nlractiiin iif tlie opposite eoriier of tlu' inoiUh. ( Kxperi- nienls of i:. L. Midliis. ) After lesions of the hallux centre, there detronerated many asso- ciation libres. both coarse and fine, wliich ))ass from the central <:yri down as far as the levid of the inferior •i'enu of the sulcus cen- tralis Kolandi. Some fine association libres were found to pass to the lobulus jnirietalis sui)erior. others to the ])osterior ))art of the gyrus frontalis su])erior, and both co.arse and fine association fibres were found to connect the hallux centre with tiie lobulus parii- eentralis. This centre was further connected, by means of fibres which ])asse(l throumispliere of the opjjosite side lieinjj: distributed in the opposite hemisphere in an area on tlie whole similar to that wh(Mic(^ they arose. The projection fibres which defj^enerate after lesion of the hallux centre could be followed through the medial iialf of tlie centrinn it OUOL riN(i AND ClIAININd TOUKTIIKR OF NEL'KONES. 1(J25 " 'rt it Cap'it nuclii vdutlitfi.. Pars fruntiiU.s capsuUr iiiUrmv. I'eiitrwuliin Ititinilis.' larnu mtjitrius. I'nidinen.- I.Vllll lllllSllIll illtlllKV. Illiibiis ixillutiiK. Iit'ijenvratvil itrva (li(iHii.i). ruin incii>il(iliii ciiiisn- Iw inti'niir. Thttldiiiits.. .{(tuetlnclus ct-rebri.- I'nlriiKir.. llil\iii.. i'v lit I kill us littirulis.. I'lci. ()l!i. — Iluri/diitiil sci-tiiiii 111' iiKPiikfy's luaiii sliiiwiii;: aria of (li'ficiicratiuii ill iiilcnial capsule. fnlluwiiiK N'siuii uC hallux ctiitri'. ( Kxporimt'iil and Iii<|)aralioii liy K. L. Milhis. i Kl(i. (147. — Di'fjini rated area in V\n. Mi>. eularjieil. i Kxperiiueiit ami iilinto- iiiicronraiili liy K. L. Melius. ' 1()L'(! TIIK NHIiVors SYSTEM. *' I s))ri>-s!)iiiiilis hitcralis of liotli sides. ' F.xpfiiriiciil iiiid plioto-niicroKnipli l)y 10. 1.. Melius. ) the fasciculus cerebro-spinalis lateralis of the opposite side of tin' cord, a smaller portion going" to the fasciculus cerebro-spiuiilis i;it (i|{()riMN(i AND ('HAIM\(} T()(}KTIIKIt OF NKl'KoNKS. 1027 (Talis of tlic sjitiic side. The relative iiuinlior of crossed and uii- erossed libres varies «'onsideral>ly in the dillereiit aiiiinals experi- mented iiiM)ii. A few libres pass down in the faseicuhis ventralis Km;. tilO. — Spinal cipi-d iit tlic level cpI' clevetilli tlionicic rout, liallux lesion. Bi- liileral (leKenenitioii. ( Kxpeiiuieiit ami |ilioto-iiiicro};ia|)li l).v K. L. Melius.) of tlie eord of the same side, wliich jjroves tliut in the iiionkey, eoii- trary to tlio general statement, there is a very feebly developed fiis- eienlus eerehro-sj)inaIis ventralis (Ki"-. (il!(). The deo'enerated libres conld he followed down throiif^'h tlw cervical and tlioi-acic coi'd without showino- diminution in number, but in the luinl)ar rejrion of the cord the degeneration in the lat«,'ral tnicts of both sides aiul in the ventral tract on the same side Ijcgins to disappear, although certain lii)res extend below the level even <)f the third sacral root. Foll«)wing extirj)ation of tjie thumb centre (coi'tex of posterior central gyrus between inferior extremity of sulcus inter])arielalis and sulcus centralis RoJandi, a little above the interior genu of the latter sulcus in the bonnet monkey) association fibres degen- erate to the anterior and |)osterior centi'al gyri. the ])osterior j)or- tion of the gyrus frontalis medius and the gyrus fi-oiitalis infei-ior and to other gyri of the cortex. A cei'tain nimibci- of ass(«'iation tibres from the thmnb centre pass through about the middle third of th<' corpus callosum to the heniis))liere of the o])|)osite side. Fine and coai-se projection fil)res degenerate from the thumb centre downward through the centrum semiovule. The line tibres , i I i I I \ " I 'J lO'JS TIIK XK 11 vol's SYSTKM. t(>niiiiiiit(> ill tlio tlialiumis, tli«> liiry:*' liluvs (pynimidal tnicl libros) occupy ill (lie iouci- lidrizontal levels of the iiitcnial cansiijc tlic middle third of the pars occipitalis or posterior limi». In the husc ^- 9 .s^. r^. ^^^^^^^^^^^^^^^^^1 ' , ■ Liiwl X W^^^^^^^^M f •■\. ■ ** ^'|SWfal ■k-i ' j^' "^I^^^^^^H »N- V :ffJ^dlN^^| ■Rk''* -A^l^^^^^^l t«ii ■hI ■;.. ': •'^ JtM i^^^^^l m&.'' ^'^V^^l 'jis^ ^^^^^1 ^^^H J. i,"^^^ ^^^^^^ .;* jj:,' ^^9 ^^^^^1 J^^HfiflH^^^^^^I '- •>■ ■-»#:« ^^^^^^^^^H ^^H^^^^rjH^^^^^^^^^^^^^^H ^^^^^H ^^^^RB^^^^^^^^H Jh||H ^^H ^^^Hv^^^^^^^^^V^B ^^H ^^p ■t^-^'i^giaBgij^Bi ^^^^^^^1 HVrv. .^^^J^H^H^SI ^I^^^^Htk^mi^^^H^^^I ^^^^Svi^!iX^^B^^^^^^^^^I B Eifl Fl(i. ().")(),— Sect ii 111 "f :>piii!il (111(1 at the level (if first cervical nnit ; (leKciicralinti ill lijjiil I'asciciihis ceiclii-o-spinalis lateralis after excisidii of tliiinili centre of left liciiiis|(licre. ( I'.xpcriiiienl and |ili(it(p-niicr(ij;ra|ili by I',. L. Mellns, ) 1 of the cerebral peduncle tlie tlmiiih liitres occupy the iiiiildle thii'd of the area as seen on cross section. A larye ntiiuber of the deyen erated (ihres pass to the stihstjintia iiiyra. Melius stiites that from a half to nearly the whole of the dejreneratioii, foUowino- h'sion of the thtmdi centre, which extends tis far its tlie cerebral peduncle, ternii nates in the substantia niyra. At the pyramidtil tleciissation in the medtillii the niajoriiy of the libres cross ovei- into the lateral pyraiii idal tract of the opposite side, iiUhotiji^h a few ifo down in the hit era! funiculus (Fiy. (iriOi. and still fewer in the ventral funiculi of tlH> siiine side. It is interesting- that the degenerated fibres do not stop in the upper cervical levels, but, as nii<;ht have been expected from the experiments of Ferrier and Yeo. beyin to leave the while matter frt)m the level of the seventh cei'vical root dowiiv ii'd, the deofonerating' fibres stetidily and (>-ra(lualIy disappear! ny liy tiiniiiii,'' into the gniy in;itt«'r until at the level of the thiril liioracic root no deg-eneriited fil)res reniiiin. It would take too lout,'' to describe all of the experiments made by Melius in connection with the facial area of the cortex, but in rf\t * „ (UIOUIMNO AND CllAININ(i TOdKTIIHIt OF NKl'liONliS. l()._>9 I 60 2 ■_M «2. i § § S a 1 8 1 *-4 w s a y^ o P^ 1 \ -■ lii;^) Till'] NKK vol's SVSTKM. aNiiiurli as \w worked principally with the cortiral area correspoiid iiitr III the iiMitor rcpri'si'iitatioii Tor opening the timiith slrai^fht, Imh results after exiirpalioii of this area may he hrielly deserihetl. The usmK-iatioii lihres t'nuii this area were carefully studied as well uh l''i(i. liW. — l)t'K<'ii('i'ut('il aifii ill Fit', ""il. I'nliU'Kcd. (I'liiitn-iiiici'iiLM'apli liv K h M.lliis.i 1 ^ ■ . the projeetiou Hbres. As rejfards the latter, holli fine and coarse fibres degenerated, the fine fibres teriniiuitin cerebral peduncle. In the cerebral peduncle the fibi'es are scattei'cd evenly over the middle third of the area, as .seen on cross section, encroaching a little upon the latei-al third ( Fijfs. C),*).'? and (554). Some fibres leave the ti-aet here to term inate in the substanti;i niyra or in the hyiiothalamic region. Farther down the remaining degenerated fibres begin to leave the {)yraniidal tract at the jun<"tion of the ptms and medulla oblon- gata, and singh» di'generated fibres coidd be follow<'d to the niudeiis nei'vi facialis of the same side ami of th(> opj)osite side to the motor nuclei of the N. ghissopharyngeus aiul X. vagus of both sides. Melius em|)hasizes the fact that all the degenerated pyramidal fibres from the hallux and thumb regions lTl»IN(J AND l'IIAININ(J ntOKTIIKK OK NKUHoNKS. l^yi s s :2 M If 'S 1 a _2 E ^ s ■« e 3 r 5 Z ^ -a ii ; ^H HHi ■ ^^^^^^1 m •'■ - 1 ... dJPI ^^^ P P^^^^l m >.'< ' ' '. '. ' ^ 1 s 1 3 1 2 1 s s i "" ^ * "^ •c ^Vi s w ^ p C ^ ^ g *: 1 « J f lib \ -^ 1032 TFIK NKKVOirS SYSTPIM. ilic iiilcnial capsul*' the film's arc all crovvdcMl f(»{rotlior at al»()nt tlii' iniddlc thin! of tiic jjostcrior liiul). '" It is also shown that a liin i-aii Ik' drawn from the lissurc of Sylvius forward, so dividing the motor area into two parts — that of the facial lesions from which lihrcs enter the anterior portion of tlu' capsule would he in the anterior division, and all the hallux and thumli lesions from which lihrcs enter the posterior portion of th(! capsule would b(^ in the .. ;l| Flii. (jr)4.— nojjoncraU'd aivii in Fift. (i53, ciilivrKcd. (PhottMnicrogr.ipli iiftn Melius.) posterior division. Tn the movement of the facial fibres backward between the u])])(>r and lower levels of the capsule they would neces.sarily, at sunie iev middle tliird (if the arcii, as seen on cross section, and do not <)ccui)y a si>acc by themselves medial to tlie lihres of tlie pvminidul tract. The significiiiKH! of the uncrossed fibres of the inramichil tract is somewluit tliflicult to understaiul. Now thiit we know that a certain number of tibres remain uncrossed even to their termina- tion, and the i)roof has been brou<;ht that eatdi cerebral hemi- sphere staiuis in connection with the groups of lower motor neurones on both sides of the rliombeneephalon jind spinal cord, it docs not seem unlikely that in the uncrossed fibres we may find the anatomical explanation for tlie jihysioiogical itecuiiari- ties of the so-called bilaterally innervated movements. Jt is iu)t impossible, too, that herein is to be sought the explamition of the curious behavior of the so-called residual jtaralyses after cerelu-al liemiidcgia, wliicli have I)ecn ably descrilu'd by Wcrni(!ke and Mann, of lircslau. The cases of hejnii)legia following homo- lateral lesion of the brain have also to be thought of in this connection, tliough it is not yet clear that the explanation of this unusual plu'nonu'non is to be found here. Tlu' light tlirown upon i]u> upper tnotor neuroiu's by studies undertaken witii tlu^ nuUhod of (iolgi concerns mainly (1) the interrelations of the cell bodies and dendrites of these neurones with one anotluM*, aiui with those of other neurones in the cere- bral cortex ; (2) tlie collaterals given oil by the axones of these neurones in various i)arts of their course; and (3) the terminal relations of these axones. For the interneuroiuil relations in tlie cerebral (!ortex the reader is referred to the studies of liamon y C'ajal.* His scheme is reproduced in Fig. (lAr). The studies of Starr, Strong, and licaniing include investiga- tions in this area. In Fig. (iali their scheme is shown. As to the collaterals given off by the axones of the pyramidal tract a number arise in the first place while the axones are still in the cerebral cortex ; others are given off shortly after their entranca^ into the corona radiata. In the jions, collaterals from tlu; jiyraniidal tract are distributed to the nuclei pontis. In the gray matter in which the axones of the pyramidal tract terminate ♦ Ramon y Oajiil. S. Tjcs noiivollos idt'cs sur liv structure (hi systoiiii' iiiTvcux cho;'. riiomiiic ot ciioz ies vi!rti'brt''s. I'ur. (iloimwald ul (."ic), (18!)4), 1)]). :ifl-G9. J I 1034 THE NKHVOUS SYSTEM. many colliitenil branches are given off; indeed it may be said that the axoiies become exhausted through the projection of numerous coUaterals. Ki(i. t),').'). -Sflicmc slidwiii;; the in'olialitc ('oiirsc <>( iiiipulscs and tlic iiitcfiii'ii- roiial coiiiH'clidiis ill tlv cortex ('crcljri. (ACtiT S. Haiiioii y Cajal. Lcs mmvcUcs idrcs. ctf,, Azimlay, Paris, IWII. p. (iti, Kif;. l(i.) .1, small iiyraiii- idal cell; />, larfif pyramidal cell; ('. />. piplyiiinrplious cells: /'.', terminal <'eiitripelal prujection tiltre ; /'', collaterals from the siiltstantia alba; fr, axone liil'iircatiiiK in the suhstanlia allia. A ,1' - V It is liighly desiniblc tluit tlie exact terniinal rehitions of the axones of the iii)})er motor neurones be more thoroughly stiuliod by means of the method of (iolgi, for we find in the bibliogriiiiliy two diametrically opposite views with regard to the relations of the terminals of these iixonos of tlie cell bodies and dendrit(\s of the lower motor neurones. Von Monakow * believes thiit the * voii Moiiakow, ('. Rxperiint'iiti'lie uiid piithdlojjiscli-iumtomiselio Tii- terstic'liimgeii iielierdie Ilaulioiiivjjrioii, dcii Seliliii^fel uiiil (he Refjiosiiiithaia- inioa. ncbst TieitriiprkMi znr Konntniss frilli erworlieiu'r (iross- iind Klpiiiliini- defecte. Arcli. f. I'sycliiat. \i. Ncrveukr., Herl., M. xxvii (18!)")), S. 1 ; 'Ml .:sB3?aai .1. iii"«i" III A w GROU i i Fl liyi-aniidal cells: k. larjte pyramidal cells with very numerous dendritt's ; :ill pyramidal cells are seen to send lonj; ai)ical dendrites up to / ; m, .Martinotii cell with (leseendinH sented. The whole conduction ])ath from the cerebral cortex to tlio muscles, involving at least two sets of superimposed neurones, is * Redlicli, K. Ueber die anatomisclieii FoljjpersehiMii'iiniiigiMi luisfjc- dehnter Exstirpationen dor motorisf^heii Uitidcmjeiitroii bei (k>r Ivatze. Neurol. Ceiitralbl., licip/., Hd. xvi (1H!)7). S. 818-832. >•' 1^ (iU()UIMN(} AND CIIAININCJ T()(JKTIIKIt OK NKUIIONKS. 1(>;{7 sonictiiiics spoken of us tlu; cortic^o-inusciiliir (;ondu(;lion path (Figs. <;:>; jind (;")8). Wo owe to (iowers cspeciiilly tho rocoguition of the ditTerciicea tU,o>v "< //a//u» ^nJ%maH Jots Gcp «ia?,vi MuScH Fig. 657. — Scheme of upper aud lower motor iieunmi's. Ltttering as in Plate II. m 1038 fl^^. TUB NERVOUS SYSTEM. O.cf. I"i(i. (ir>s. Sihi'UK' (tf upjKT and lower tuotur iicurDiics. LctU'riiig saino a^ in I'liitc I. flUOUI'IXC} AND niAINING TOOETIlElt OP NEUIIONKS. [()'.]<) P'ili' in the effects of lesions involving on the one hand the lower motor neurones and on the otlier the upper motor neurones. Gowers described these us (1) lesions of the lower motor segment and (2) lesions of the upper motor segment. If the lower motor neuroiu-s be seriously injured there results the so-called flaccid paral3sis. The muscles undergo rapid atrophy, and exhibit the so-called eler "cal reaction of degeneration. On the application of the galvanu; or the faradic current to the de- generated nerve there is no response. Hut when the muscle is stimulated, while tiiere is no response to the faradii' current, there is a response when the galvanic current is applied, which, however, is not that which nornuilly occurs. Instead of being sharp ami (piick, the contraction is slow and lazy, ami, in oppo- sition to the rule in health, the anodal closure contraction nuiy be greater than that on cathodal closure. Since the reflex arc is destroyed when the lower motor neurones are degenerated, the so-called deep reflexes are in such instances abolished and the muscular tension is diminished. The groups of muscles para- lyzed give tiie clew to the localization of the lesion. When the upper motor neurones — for example, those the ax- ones of which correspond to the pyramidal tract — are degenerated there is also paralysis, but of an entirely different nature. Instead of the flaccid, markedly atro])hic ])aralysis of the muscles with elec- trical reaction of degeneration, there occurs the so-called spastic paralysis, accompanied, as a rule, by no more atrophy in the muscles than that which would naturally follow disuse. The deep reflexes in such instances are of course exaggerated, and the tension of the muscle may be markedly iiun'cased. The dis- tribution of the paralysis will of course be entirely difTerent from that which occurs with lesions of the lower motor neurones, and the situation of the lesion may be ascerfained by careful consid- eration not only of the nature and distribution of the paralysis, but l)y a consideration of the accomiiaiiying phenonuuia due to associated lesions in other Jierve paths.* * Cf. Sccttioi) on Nervous Diseases in Osier. W. Prini'i|iles and Pnictice of Medicine, :{(l ed.. New York ( I Si).S).— Gowers. \V. H. A Manual of Diseases of tlio Nervous System. I'lniadelphia (IHUi).— Mills, (". K. The Nervous System and its Diseases. Philadelphia (1898). V! % * ii 1 „ ., CHAPTER LXIII. IXTEUMEDIARY AND Ul'l'ER MOTOR XEl'ROXES (CONTINUED). The frontal cerebro-uorticopontiil palli. or faseieulus pallio-frontivlis, pnr> frontalis. 3. Those the Axones of which Correspond to the Frontal Cerebro-Corticopontal Path. Tins path, doscribed by Flechsig as tlie frontale Grosshirn- rinde- Briickenbahu y is assumed by liim to arise in those regions of the cerebral cortex which correspond to the distribution of the system of sensory fibres which he designates as No. Ill ; that is to say, the feet of the tliree frontal gyri, and possibly also the middle jiortion of the gyrus fornicatus (Fig. 65!)). The axones from the large pyramidal cells of this region of the somiesthetic urea running in the centrifugal direction toward the internal caj)sule become medullated at a period somewhat later than the fibres of the pyramidal tract. The fibres pass through the pars frontalis of the capsula interna near the genu, pass through the base of the cerebral peduncle medial to the fibres of the pyramidal tract, and, according to Flechsig, terminate in the nuclei pontis. It is Flechsig's opinion that this frontal cerobro-corticopontal path is concerned with the movements of bilaterally innervated muscles, such as those of the eyes, neck, and trunk. The motor impulses concerned in the speech movements may also, lie believes, be carried by nbi'es of this path. There is a good deal of evidence, however, that the speech path is se])arate and distinct from the frontal cerebro-corticopontal path. By means of neurones extending between the nuch ' pontis and the cerebellum by way of the brachium pontis, the frontal cerebro-corticopontal path throws the cerebellum under the influence of the opposite cere- bral hemisphere. In the pars basilaris pontis the frontal cerebro-corticopojital path at first occupies the dorso-medial portion of the longitu- 1040 %' i^ OllOUl'INa AND i;iIAININ(} TOdKTllKU OF NKUUONKS. 1(»41 (linal fibres, but in more ciuidiil planes it turns ventralwanl, su that it comes to lie ventral and somewhat medial to the libres Oct. N abducens'^ / N. facialis.' "«(,«» irjiw iN.C«r»J. Flu. 659. — Scliemo of I'ronttil cirobro-cortictiiHintal path. Lettering us in I'liite II. of the pyramidal tract (Fig. OGU). Tliis tract may degenerate after lesions of tlie middle and inferior frontal gyri, in wliich event the dorsal bundle of the anterior limb of the internal capsule undergoes secondary degeneration, and the frontal cere- t '! 1042 TIIK NKltVOrs SYSTKM. r M I i ■ I.; F i ji i'K ?' ^' I ' ^ ' i Fks. (itil. — Sccinidary (Icuciicnitiuii fdllowiiif; Icsiini in the Icf'l middle und infe- rior rnmtiil K.vri ; the deKenerated IVontiil ( crelird-eorliciipontal path isshcpwn. (After ('. von Monalvow. (itdiirniialh.dofjie, Wien, ISitT. Fi^s. lS(i ls!t.) A. TransTerse section at tiie h'V( I of the niiiidh' of tlie tlialannis passing; through the nn(deus hypothalainiciis (I'orpus Luysi i ; in//, nnr'!', fasciculus thalamo-mammillaris Vic(| d'A/.yri. H. Transverse section through the posteriiu' extremity of the thalamus and tlu' ret rolenticular portion of the capsula interna; />'.l, Ui-iudiinm ciuijnnctivum : // .V. tractus opticus ; /'(/;•, fasciculi cerehro-spiuales ( pyramidales ) ; I'nl, pediiucnlus cere- liri, pars hasilaris ; A'A'. nucleus ruber ; '/'/(((/, thalamus: mil. ventral Kroupof nuclei in the thalamus. ('. Transverse section throuj;li the pons ami .junc- tiiui of the colliculus superior with the colliculns inferior: II. I, lirachium conjnnctivum : />'c.l, lirachium pontis ; kcIi, lemniscus. I). Transverse sec- tion throu<;h the uppermost part of the medulla olilon^ata ; de;;enenition no huiKcr demonstralile : llr.l, l)ra(il. ; •'• V \ ' ,1 fP: l(»4-t TIIK NERVOUS SYSTKM. in :; I It? I J •*, ! bro-corticoponhil path can be followed into the most niedial portion of the base of the cerebral i)e(liiiicle. In such instances the ratiiation of the nucleus niedialis tlialanii and a portion of that of the nucleils lateralis thalanii atrophies, and after a time disappears (von Monakow). An example of degeneration of the frontal cerebro-corticoimntal path is shown in Fig. Wl. 'J'Jiis bundle, esj)eeially in the base of the cerebral })edun(>le, has been called, though iinproi)erly, Arnold's bundle. Zacher * has recently denied any connection between the frontal lobe and the medial segment of the base of the cerebral l)eduncle. In his case, in which the medial bundle of the pes was degenerated, the anterior portion of the posterior limb of the internal capsule was entirely free from degeneration, lie believes that the medial bundle of the pes has its origin in all probal)ilitv from fibres which run in at the base of the nucleus lentiforniis in its posterior part from the outside. These fibres, he believes, in part at least, have their origin in the island of Keil. Dejerine attributes the origin of the fibres to the Holandic operculum and adjacent part of the frontal operculum. One of Spiller's f cases would indicate that at least a })ortion of the bundle has an origin anterior to the Holandic operculum. * Zacher, T. Beitriigc zur Kenntniss des Faservcrlaufes im Pes pedumiili sowie ucber die corticaloii nezicliuiigeii iles (\(ri)iis jsreiiiculatiiin internum. Art'h. f. Psychiat. u. Nervenkr., Herl., Bd. xxii (1890-"!)1), S. G54-6!)8. t Spiller. W. (t. A ("oiitributiou to the Study of Secondary Depeiieratinn fdllowinj; ('(>rel)ral Lesions. Trans. Am. Neurol. Assoc, 1897, New Vmlc <18i)8), pp. 310-338. ) CHAPTKK LXIV. TXTKIfMI'.niA WV AND riM'KIl MOTOU \ Kl'KC/N KS ((ONTI MKO), I'lic Ifiiiporal cercbro-corticopontal path — Paths from the lohiis oi-uipitalis to the corpora quadrijjcinina — Olfactory roflox pat lis. 4. Those the Axones of which Correspond to the Temporal Cerebro-Corticopontal Path. TifKSE are tlio noiiroiios the iiiecliilktod axonos of wliicli occn])y tlie most latofal segment of tlio base of tlio corobral poduiicle designated by Flechsig as the tempornle Grosshiriiri/Klc- lirurkenhnhn. The bundle is usiitilly called Tiirck's bundle, quite impi-operly it would seem, since the bundle concerned is separated by a wide area from the region found diseased by Tiirck in hemiani\3sthesia.* Flechsig believes that the cell bodies luid dendrites wliich give origin to the axones of this path are situated in the auditory sense area of the cerebral cortex (gyrus tenijioralis superior et gyri temporales transversi). The axones, he believes, pass down through the posterior jmrtion (retro-lonti- form portion) of the pars occipitalis capsuhe interna; to the lateral region of the base of the cerebral peduncle. Thence they go into the pons and eiul there in some way unkiu^wn to Flech- sig, perhaps, he suggests, -joing ever directly into transverse fibres of the jmns or ending in the nuclei pontis. lie is inclined to think that, like the frontal cerebro-cortioopontal path, this temponil path represents ii mode of connection by way of the briichium pontis of one cerebral hemisphere with the op})osite cerebellar hemisphere. The fibres are medullated at a later ])eriod than the fibres of the pyramidal tract. Von Monakow describes the temporal cerebro-corticopontal path as occupying, in the cerebral extremity of the pons, a dorso- lateral lield, which it follows until it becomes exhausted in the gray matter at the caudal extremity of the pons, except that from t k* * Op. ril. 1045 ,4' (i w l(»4r> TIIK NKUVOUS SVSTHM. the middle of the pons on it is locjited exactly dorsal to the librcs of the pyraniidiil tniet. The fibres of tiiis bundle, like all the other fasei(aili longitudinales of the pars basilaris pontis, arc separated from one another by fibne transversa; ])ontis and l)y liie masses of rius to the colliculus superior of the corpora quadrigctuiiui and the stratum griseum cuntrale aqueductus cerebri. Wiictlier or not any of these axones actually reach the nucleus iiervi oculo-motorii and the other eye-nuiscle nuclei directly is not known ; it may be that another neurone is interposcil between the terminals of the <»ccipito-niesence{)halic neurone aiul the lower nu)tor neurones. Indeed, this is the view which von Monakow is inclined to sup- port, and it is quite in accord with the prevailing ideas with regard to the superior colliculus, whiidi is geiu'rally looked upon as the central organ for the governnunit of the eye-muscle luiclei. That the fibres from the occipital cortex to the nu'scncephalon do actually pass through the lateral segment t)f the cerebral peduncle is made very probable by the studies of Zacher.* He believes that the tibres from the occipital lobe are nu)st laterally placed, those from the temporal lobe being situated between these and the fibres of the pyramidal tract. The cases of 8ioli f and Winkler | make it not impossible that some fibres from the lol)iis i)arietalis also pass through the lateral segment of the base of the cerebral peduncle. 6. Those the Axones of which Connect the Rhinencephalon with the Lower Motor Neuiones. These have already been dealt with in connection with the olfactory sensory neurones of the second and higher orders, to which tile reader is referred. * Zaelier. T. |{i'itnij,'o /ur Keiiiitniss des Faservorlaufes im Pes pcdun- cufi sowio iiolicr (lie I'orticiifi'ii Heziefiiiiip'ri des Corpus p'liiciilatuiii inter- num. .Vrcli. f. iVyeliiat. u. Nervenlwi./'.. suhnioleeular plexus; O'/. /'./'., ^reat pvraniidal i)lexus ; J'ol. nuiriduc plexus ; 11'., white niatt4'r. of tiervc J. Atidri- (' (Hires ; ^lllllllii : /'., poly Y-' I' kl .jU> «KOUPIN(J AND (ilAlNING T<)(1KT1IF,1{ oF NKrUONKS. i(»r>! Tlic majority of those neurones liiive alreiidy been described in connection witli (1) the sensory neurones of the hijj;her order and (v) the upper motor neurones. Thus (a) t\w diencephalo- toleneephalic neurones of the general sensory patli, (/>) the radia- tio occipito-thahimica (iratioleti of the visual conduction path, ami (r) the radiatio corporis geniculati niedialis of the auditory conduction path represent corticopetal projection neurones. Again, the libres of () the frontal cere- .♦.V-^'-'^ ^i"' j- Fig. 6(54. — .Siifriltal section N'o. Its, tliroufih the Iiraiii uC a liahr sliorlly aftor birth, illii^tratiiif; the impjcctioii til)rcs to the soiiiii'siiu'lic area. C.i., caiisiila intcriiii ; (l.c.ii.. fiyn\s ('ciitralis anterior; (1. r. ii. , fiyrns centralis j)osterior; /,()/). friiiit., lolms frontalis; l.oh. iiicii}., lol)ns occiiiitalis ; 'I'll., tlialanins; '/'.((.. tractiis optiens ; .■;, nueleus Ivnlil'orii'.is ; ;■, corpus KOiiiailatnni lalenile ; v. I., ventricnlns latenilis. bro-cortieopontal path, (r) the temporal cerebro-corticopontal path, and (d) the fibres running from the occipital lobe to the mesen- cephalon represent the axoncs of corticofugal ])rojection neu- rones. The ease with which these projection axones can be fol- lowed in the meduUating brain is well illustrated in Fig. 004. If an area of the cerebnil cortex be extirpated, especially in the young animal, the axones of projection neurones, whether they bo corticopetal or corticofugal, undergo a change. In the case of the corticofugiil tixones secondary degeneration with absorp- tion rapidly takes place ; in the case of the corticopetal axones (!!1 I H It 11 II '■r-'! I :ii* i'i. I Id;') 2 THE NERVOUS SYSTKM. there is less rapid (leyeiierutioii or utropiiy, which can be traced to their infracortical origin. Tiiese infracorticul areas in wliieh the corticopetal teleiicephalic ])rojection fibres originate, and which, like the fibres tiiciiiselves, undergo atrophy or degenera- tion after extirpation of the area of the cortex in whieli tiiev terminate, are known as " cerebral api)anages " or " dependencies." \'on Monakow has recently paid a good deal of attention to these areas, and has described tlieni under the term (irosshirnantheile. He believes that they are phylogenetically young, for they are absent in lower forms, and increase progressively in size and num- ber in direct proportion to the development of the cerebrum. According to his view, the majority of the nuclei of the thalannis and geniculate bodies, the substantia nigra, and portions of the corpora (piadrigemina and of the pons belong to this category. The various cerebral dependencies are of different age, as far as can be judged from })hylogenetic studies, the olfactory organ, the visual sense, and hearing having been successively developed. (B) Commissural Neurones. ClIAPTKU r.xvi. il COMMISSURAL NKIROXKS OK TlIK TKLEN(^EPII.\LON. Ilptoromoric t('l('n('('phali', eoiniiiissura anterior eereliri ; I', fasciculi cerelirospinalcs (pyrauiidalesl ; n, jiyraniidal cells Kivint,' rise to axones of pyraniiilal tract; oiw senilinK a linili of hi furcation through tlie ccu'pus callosuin to t lie opposite lieniisphere ; h, pyianiidal cell .sending axone through coriius callosuni ; c, liyraniidal cell with an a.xone wliicli Idfiirciites ; one noiiifj tlirouj.'li liie corpus callosuin to the ojiposite hemisphere, the other lieiiiK distriliuled to the <'ortex of the heiuispiiere of the siinie side: -"S4). p. Mm \) I i.' lOaO tup: nervous systp:m. 1 Tho pars posterior of tho iinterior coiuniis.suro is believed to associate the activities of a portion of the temporal and of tlio basal part of the occipital lobe of one side with thosi; of similar cortical areas on the opposite side. In devel- opmental stages of the or- tfaiiism the pars posterior of the anterior comnnssure stands in intimate relation to the ventral portion of the spleniuni corporis callosi, si'ul is really morpholojjically widely separated from the pars anterior. The view is ])revalent that the commissura anterior cerebri is a snpplement to the corpus callosum, its axones originating and terminating in areas of the cortex unprovided for by that body. The comparative anatomy of the structure has been studied l)y Osborn,* C". J. and ('. L. llerrick,+ Edinger,J Smith,* Syming- ton,! '^^^ by Adolf Meyer.'"' Fin. (ititi.— .S'luMiK^ of tho coniinissiii-n ante- rior cerebri : /)./., pars posterior; y.".. pars aiileiior. (After A. Haulier, Lelir- liiieli cler Aiialoinie des Meiiselieii, \' . Aiill.. M. ii. Leip/,., 1S!)H. S. :5SS, Vin- 3:5(i. ) * Osborn. H. F. The Origin of the Corpus Cnllosum, a Contrihution upon the Cerebral Commissures of the Vertebrata. Morphol. Jahrb., Leipz., B(l. xii (1M86-HT), S. 2'.]3; '>;!(). f Ilerrii'k, C. J. The Cerebrum ami Olfaetories of the Opossum Didel- pii ,s Virjiiniana. J. Comp. Neuml., Cincinnati, vol. ii (1802), jij). 1-20.— The Commissures and Ilisloloj^y of tiie Teleost iirain. Anat. Aiiz., Jena, Md. vii (1891). S. G76-(iSl.— Additional Notes on the Teleost Brain. Anat. Anz., Bd. vii (18J)2). S. 422-4;{l. — The Callosum and Hipiiocampal Region in Mar- supial and Ijower Brains. J. Comp. Neurol., (iranville. vol. iii (1H!);3), pp. 171-182. — Also C. Ii. and C. J. Herrick. Contributions to the Morphology of the Brain of Bony Fishes. J. Comp. Neurol., vol. i (18!)1). p. 211 ; 3:53; and vol. ii (1S!)2|. i.p. 21-72. J Fdinger, L. Vergleiciiend-Rntwickelungsgeschichtliche und anato- misehe Studien im Bereich der Ilirnanatomie. Anat. An/... Jena, Bd. viii (1893). S. 3()r)-321. * Smith, (t. E. Notes upon the Morphology of the Cerebrum and its Commissures in the Vertebrate .Series. Anat. An/.. Jena. Bd. xi (IBO.'i), S. 91-96. — Morphology of the True jjimbie Lobe. Corpus Callosum, Septiiiii Pellucidiun, and Fornix. J. Anat. and Physiol., Lond., vol. xxx (1895-'96), pp. l.')7; IS.'); 450. II Symington. J. The Cerebral Commissures in the Marsupialia and ]Mono- tremata. J. Anat. ami Physiol., Lond., vol. xxvii (1892-93), pp. 69-84. ■''Meyer. .Vdolf. ('(^ber das Vorderhirn einiger Reptilieti. Tnaug. Diss., Leipz. (1892), S. 1-73 — Zur llomologie der Fornix eommissur und des .Si>p- tum lueidutn bei deu Reptilien luid Silugern. Anat. Anz., Jena, Bd. x (1894-'9r)), S. 474-482. OUOUPING AND CHAINING TOGETHER OF NEURONES. 1057 3. Those the UeduUated Axones of which correspond to the Fibres of the Commissura Hippocampi. This ill in.iu and iiiiiininiiLs consists of a bundk- of niodnllatcd axones extending between tlie crura foniicis of the two sides and connecting the hippocampi witli one another. Fibres run in both directions, forming apparently a true commissure, tlie so- called psalterium or lyre of David. It can be divided into two j)arts, one more dorsally, the other nujre ventrally located. This is especially true of the commissura hippocampi of animals. The axones probably have their origin in the pyramidal cells of the hippocampus. \l -^ i •!''i m (C) Association Neurones of the Telencephalon. CKAPTEK LXVII. ASSOrr.VTIOX XKIKOXES ok TIIK TKLEK( epiiai.ox. Tiiutumerif telencpplialic iKuiroiu's — Fibni' projiria' — Stratum calcariiiuin Fuseicultis occipitalis pcrpcndicularis — Kascieiilns occipitalis truiisvcr- stis ciiiu'i — Fasciculus occipitalis ti'aiisvcrsus jjyri liiii^ualis — Stratum jmipriutu cunci — Tiic ciuf^ulum — 'I'iic fasciculus loujjitudiualis supe- rior — The fasciculus uiiciiiatus — Association bundles of the fornix Tlic ta[)elum. TiTESE mi/rlit well be called the intrinsic tautomeric tcleneeph- alic neurones. By them is to be understood neurones which connect a portion of one hemisphere witli another portion of the same. Tliese association neurones may be divided into (1) tlioso with short axones and (3) those with long axones. The association neurones with short axones include the fibrai propria' of the cerebral ii the external layer of tanfjential (ibn's. the so-called stripe of (ienm\ri. and the su|ier-radiMl plexus of Ivlin^rcr in (he ext Tnal zone of the cortex as will as the intcrrailial plexus situated in the deeper jiortion of the cortex. inr)H m C4R0UPING AND CIIAININO TOOETIIEU OF NEURONES. I059 seheniiitic reprpsentation of Ramon y Cajal's views concerning tlie association neurones is reproduced in Fig. liGI. Fl(i. t)()7. — Scliciiic (if ail :iiitcr(i-i>ost('riiir section tlinmf;li tlic ccrcbniiii sliowiiiK tlu> (lisiH)sitiiiii (>r tli<' axiiiU'S of iissnciiitidli iicurcnK'S which cciiiiicct tlic liihiis frontalis witli tiic luluis occii)itaiis. lAftcrS. Ivainon y (ajal, l-cs iHiuvcllcs iilccs, etc.. A/.onlay, I'aris. 1 Sill. j). .">!•, Kitf. 4. ) o, ^. c, i)yiaiiii(hil cells : (/. tcniiiiial of an axone ; <\ collater;'l.s of associiitiuu a.vones; /, tilires of corpus callosuui cut transversely. 1. Those with Short Axones. Tlie short association neurones liiive been most carefully described, especially in the occipitid aiul frontal lobes, by Wer- nicke,* Saclis,t Vialet,! and Dejerino.* Among these may be mentioiuMl for the occipital lobe : (1) The stratuHt cidatrinum (Fig. 0G8), uniting the superior lip of the calcarine fissure to its inferior lip by its shorter fibres, and the medial surface of the cuneus to the inferior and meditil surface of the gyrus lingualis by its longer fibres. (^) The fnftciculiis ocripitalix irrfiailis, or perpendiciilarix, of Wernicke, II uniting the superior border of tlie occipital lobe to its inferior surface. As a matter of fact, it connects the gyri occipitales superiores with the gyri occipitales laterales and the * Wernicke, ('. Lehrbiieii tier Geliiriikriuikhfitcn fUr Acrzte mid Studi- reiiile. Kassel u. IJerliii (1H81-S;}). t Sachs, II. Das llciiiis|)lu'ireiimark dcs ineiiscliliclicii Grusshiriir.. I. Dor Iliiiterliaiiptliiiipen. Lcipz. (tSi>'.i), p. iU, 4to. — Vortriigc iiebcr IJati uiul 'riiiitij^keil (Ics Or )ssliiriis uiid die Lelire vmi der Aphasie uud Seelcnbliiid- iicit fiir Aer/.te mul Studirciidc. Uroslau, p. '^!IG, Hvo (lHi»;{). X V'ialet, N. Los centres ceivbraiix do la vision ot I'apparoil norveu.x vis- uol inlra-ceiebral. Par. (bSOIS). — Notc^ sur roxisteiioo a la jiartio iiifi'riouro du lobe (iccipilal d'lin faisooaii d'association distinct, lo faisceaii transversalo, dii lobulo liiijjual. ('(inipt. rend. Soc. do biol.. Par.. J), s., t. v (18!»a), pp. 703- 795. • Dejerine, .1. .Vnatoniie des nln>s nerveux. Par. (bSit.")), pp. 712-786. I SlraUiin propriiiiii cDiivexitatis of Sachs. yl 10^)0 THE NERVOUS SYSTEM. L> 1:' gyrus fusiformis. Anteriorly it extends between the gyrus iuuni- laris and the gyrus temporalis niedius and the gyrus temporalis inferior. JtcS. 0, ^« itrprU Fici. 008. — Vi'i'tical tnuisvcrst' Sfction of the left occipital lobe to show the oriKiii and course of the sliort association tiln-cs of tlic lul)ns occipitalis i partly schematic). I After,!. De.jerine. .\natoniie des centres nerveiix. Paris, ls»t5, p. 7h:}. V'ijr. US'). I (\ cimeus : /(((-. libra' propria- ; Fli, fasciculus lonffitudiiialis in- ferior ; J'thj r. fasciculus occi])italis trausversus K.vri linKualis ; /^•^', fasciculus (K'cipitalis Iransversus cunei ; Fiis, tiynis fusifonnis ; /i<, sulcus occipitalis; A', tissura caUarina; /.;/. fjyrus liufiualis ; /(/, sulcus of j;.vrus liunualis ; Oi, "2. "a, syri occipitales; (z^, sulcus oceiiiitalis ; Or. fasciculus occipitalis verti<"ilis; iit, tissura collateralis ; /(d. tissui-.i parietalis occipitalis ; ncl ij, tiyruA profundus contU'<'tiu}; cuu<'Us with the fj.vrus foriiicatus ; liTli. railiatio oc- ciliito-tlialaiuica (initicdeti ; sll. stiipe of Haillarjjer ; slrK. stnitiiin calca- rinuiu • KtijirC, stratum |)ropriuui cunei; '/Wy), tapetuni ; 1', ribbon of Vic(i d'Azyr; I'oc, coriiu posterius veutriculi lateralis. (3) The faxcirii/its orcipitalis tranxversvs cunei* extends from the superior lip of the calcarine fissure lateralward and • Stratum eunei tran.sversum of Sachs. GKOUPIXO AND CHAINING TOGKTIIKR OP NKl'RONKS. loOl w^ m then curves uj)\vjird iiiid probably tcrmiiiates in tlie nortox of the convex surface of the occipital lobe. According to Sachs, some fibres go obliquely forward and iatonilvvard to the lobulus parietalis superior and the gyrus angularis. (4) The fascifidiis occipitalis frtinsccrsiis (ji/ri liiH/unlis of Sachs and Vialet extends from the inferior lip of the caUiarine fissure (gyrus lingualis) lateralward to the convexity of the oc- cipital lobe (gyi'i occipitales laterales). It is for the inferior lip of the calcarine fissure what the fasciculus ocicipitalis transversus cunei is for the superior lip of the calcariiu' fissure. (5) The stratum propriuni cunei of Sachs consists of vertical fibres extending from the superior lip of the calcarine fissure vertically upward to radiate out into the cortex near the junction of the medial with the lateral surface of the hemisphere. In the frontal lobe fewer distinct bundles of short association fibres have been nuide out. According to Dejerine, the fibrae propria? of the frontal lobe are grouped around the corona radi- ata, some extending transversely between the medial surface of the frontal lobe and its orbital and lateral surfaces, others ex- tending vertically and connecting the various gyri of the lobe with one another. Still otlier bundles assume a sagittal direction, especially those in front of the substantia perforata anterior. Similar short association neurones have l)ee]i described in the lobus temporalis as well as in the insula. Hut thus far our knowledge of these bundles is too limited to nuike their detailed consideration of profit in this place. \ 2. Those with Long Azones. The association neurones possessing long axones have been better studied, but the opinions of various investigators concern- ing them are still markedly contradictory. Without entering into the various polemics the following statements may be considered to represent the consensus of opinion at present regarding these bundles. Of the long association neurones the most imjwrtant are (1) the cingulum, {'i) the fasciculus longitndimdis superior, (3) the fasciculus unciiuitus (4), association bundles of the for- nix, and (5) the taj)etum. The cinyuhim * belongs, properly s})eaking, to the rhinen- * This bundle was doscribcd under this name by liunlath. It was called the fornix pcriphericus by Ariuild. 1 " m If I strK VHV2 THE NERVOUS SYSTEM. cephalon. The buiulle extends in a sagittal direetion close to the; medial surface of the cerebral hemisj)here in the white mattoi" of cm Ciiiolk) Fl(i. (ifiit. — KiiciisiMcdiiilis licniisiilin'rii siiiistri sliowiiit' tlic ciii^juhim. tlic fascii' iilus liiii^itiiiliiialis iiitV riur. mikI (illicr IiuikIIcs of assiiciatioii liltrcs. (Al'ttr ,1. Dc.jcrini', Aiiiitiunii' ilcs ((litres lurvcnx, I'aris, IS!!,"), p. TrvJ. Fit;. !574.) (', cimciis; ('iiiii'(i). fasciculus autcrior of tlu' ciuKuluiii ; C'ntiiUn. iiori/dulal m- superior l)un(llc of the ciunuluni ; ('imti p ). jiosterior liuudle of tlie ciuKuluin ; fill, sulcus ciujiuli ; cm', vertical portion of sulcus ciiifjuli ; Fhi. liawil inlernal fasciculus of Huidacli ; /■'//', fasciculus loiinitudiiialis inferior; /•'».<, fiyriis ftisiforniis : //( /, ). syrus liippocainpi : A', lissura calcarina : /,. f,'yrus cinf;nli ; Lij. jiyrus liiiKualis ; /»/•'. medial surface of y;yrus I'rontalis siipcrioi' ; nt, lis- sura collati iiilis ; I'nic, lobulus ])araeeiitralis ; juiir. siilcos in front of loliulus paraceiitralis : /»). lissura iiaiieto-occipitalis : /')('. pra'cuneiis; so. sulcus snli- (irliitalis of liroca ; sIrK. stratum calcarinuni ; Vs. K.vrns temporalis inferior; Til. thalamus. -50 the two main parts of the gyrus fornicatus, r.amcly, the gyrus einguli and tlit^ gyrus lii{)[)0('iuniii. Dejerine describes it as tin arcuate bundle which turns around the rostrum, genu, trun- eus and splonium of the corpus cidlosum. At the isthmus gyri fornicati it goes into the depth to enter the gyrus hippocampi, through which it extends toward the uncus. The bundle, how- ever, is not made up of tixones which extend the whole lenglii of the cingulum, but of a great number of shorter axoncs which are ever entering and leaving the bundle. According to GROUPING AND CHAINING TOGETHER OP NEURONES. loO.S Beevor,* it consists of three iiitlejuMidont fasoicnli — one anterior, a second horizontal, and a third posterior (i^'ig. (idli). The ante- rior bundle, he believes, connects the substantia perforata ante- rior, and especially the region of the termination of the medial olfactory stria, with the anterior extremity of the frontal lobe. The horizontal fasciculus (extends between the medial lateral sur- face of the frontal lobe and the gyrus cinguli, while the jtosterior fasciculus situated chiefly in the gyrus hippocampi connects this gyrus with the gyrus lingualis, gyrus fusiformis, and the cortex of the polus temj)oralis. 'L'he cingulum in the developing brain is shown in Fig. (J7(). "t \[axf m ••^^^A rl .^' /' \ Xt iMi! \f' ctu ca I ii Fi(t. (>"0, — Marclii prcininition sliowiuf; dcgonpnitioii in dog's br.iin iiftiTflcstruc- litiii of the lolms tVoiilalis. ' After Slnilsowski. taken fnini \V. von Hecliterew, ])ie lA'itiinKslialmeti iindeliirn und Kiiekeni..ark, Deutsch von K. WciiiIxT};. II. Aufl., Lei|i/., ISdit. S. fidS, Fis;. r);!r>. ) (•((, eon'.niissiini anterior eereld'i , fornix fibres in the septum. The fasciciilu ft loiifjitiu/innUs superior,} trianguhir in coronal sections of the brain, extends as a curved bundle in a sagittal * Boevor, C. E. On the Course of the Fibres of the Ciufjulum and the Posterior Parts of the Corpus Ciillosuni mid Koriiix in the ^luiinospt Monkey. Phil. Trans. i{oy. Soc. 1H91. I,„i,(i. (1H92). vol. elxxxii (H.). pp. i;{o-l!t)». f Fasciculus areuatus of IJurdach. !- -',,r f I 'H ' l(trt4 TIIK NERVOUS SYSTEM. direction, apparently between the frontiil lobe and the occipital lobe (Fig. 071). The cell bodies of the neurones, which give rise to the axones which constitute it, have not been well localized. Fl(i. (171. — T.!itcnil surfacp of tlic left (■crcln-al licniisiilicn'. Tlic cdfrcs of tlic fis- siini (•ortion of sulcus interparic- talis behind the U|)per pari of tlu K,vrus ccntmlis ]ii(steri(]r ; /))(, suhlis pra- ceutr 'lis , /', sulcus centralis Roland i ; Sin >. >'( /), anterior and vertical rannis, anteri'ir horizoutalis, and iiinius anterior ascendens of tissura (ciehri lateralis (Sylvii 1; 7'i, f;yrus temporalis superior ; '/'•■, ^ryrus tiinporalis medins ; ^, sul- cus tciniKUiilis superior; I'. I', vertical rami of the sulcus temporalis supe- rior; Tp. fiyri tenii)orales transvcrsi ; I'N, fo.ssii cerebri lateralis ^ Sylvii '. It would appear that the axones of the bundle are of viiriablo length, the majority of them not running through the whole extent of the fasciculus, but, as with so many of the association bundles, axones are ever entcing and leaving this fasciculus. Among the axones in it are doubtless some extending between GKOL'l'lXG AND CIlAIMXa TOOKTHEIl OP NErilONPX 1065 the gyrus ti'inponilis superior aixl the inferior frontal gyrus. Tliis bundle on tlie left side is therefore, in iiU probability, of the highest importance in connection with the functions of speech, since in the gyrus temporalis superior is located the centre for word memories, while in the gyrus frontalis inferior is situated the centre for memories of the movements concerned in the ar- ticulation of words (Uroca's centre). It is highly pn-bable that axones run in both directions in the fasciculus longitudinalis superior. The ftisciruliis hiin/itialiiKf/ix inferior* is usually described as extending between the lobus occi])italis and the lobus tempo- ralis. It runs for a large part of its course close to the radiatio occij)ito-thalamica (Jratioleti, but can, as a rule, be easily distin- guished from the hitter (Fig. GI2). In it, too, in all probability, are axones running in both directions; in the one case the cell bodies of the neurones to which these axones belong are situated in the occi[)ital lobe; in the other the cell bodies are situated in the more anterior parts of the brain. The majority of the a.x- ones, however, ap])ear to have an occipitofugal direction. It is believed by the majority of investigators that a great many of these axones terminate in the temporal lobe, especially in the gy- rus temporalis superior, and the idea at once arises that tiiis bun- dle is the one concerned in connecting the visual sense area of the occiipital cortex with the auditory sense area of the temporal cortex. These areas are undoubtedly connected, directly or in- directly, by means of association neurones. That the fasciculus longitudinalis inferior is, however, the bundle concerned is by no means definitely proved. The ditViculty lies in the faet that in the anterior part of its course it is extremely difficult to differen- tiate fibres which belong to it fro!n other fibres which are adja- cent to it or even mixed up with it — for example, the medullated axones from tlie corpus geniculatum mediale and many of the cortipetal axones from tlie nuclei of the thalamus. Flechsig ap- parently denies a connection of the fasciculus longitudinalis in- ferior with the temporal lobe; indeed, he inclines to the view that much of this bundle consists of the medullated axones of projection neurones. The majority of investigators, however, insist upon the connection above descril)ed, and attribute many \ * Stratum siigittale externum (Sachs); fai.sceau neriisitij (Charcot, Ballet). I TV.': 1(h;<; TIIK NKHVOUS SYSTKM. of tlie visiuil disturban(!os iiccompiinyiiij; uphusic; lesions to inter- ruption of the fibres of this path. Fia. 672. — Vertical transvcrsi' scctiDii jiassiiij; tlii'ou<;li the |)(>sterii)r part i>r tlie pra'C'uiieiis, tlii' lissiini parieto-occipitalis, tlie tissiira eal<'ariiia, etc. Metlnid of Weifjert. (After ,1. Dejeriiie, .Viiatoiiiie des centres iierveii.x, 18!),'). p. 7tiH, Fifi. I5S4. ) /•'/(', t'a.sciciilus loiiKitiuliiialis inferior; Fin. foniix nia.inr ; yVcS fasciculus tninsversus cuiiei ; /''».s\ ;;.vrus fusiforinis ; in. sulcus occipitalis ; iii. sulcus iuterparietalis ; A", (issura calcarina ; /,;/, n.vrus liuKualis; ()l, O3, vV ' .r ' l(i(>8 THE NKKVOUS SYSTKM. ¥ ternal capsule. He j)'-ofers, therefore, to describe it as the fas- liculiis (iccipi/a-fnmlnlis, identifying it with the bundle de- scribed by Meynert as the radiation of tiie nucleus cuudatus and T. OF . V\ A ds CA OF(Top) Fui 073. — Two vcrticiil transverse sectimis fron, m cerel)!-!!! Iieiuisi)liere, with .■iKenesis of tlie corpus eallositni. i.M'tef Forel and Oinifniwic/,. from .1. Dejeriiie's text-lxpok.i A. Scetioii iiassiiin lliroiijili piilvinar (if uptic tlial- aiiiiis. H. Section alioiit '^(1 mm. I'artlier IiacU. .\. .l/r, al veils ; C.i, lii|)|)o- eainpus (cornii amiminisi; Cij. fascia deiitata liippi ; /,i, fjyrus cinuuli ; A'c. inicleus caudatus ; ,V<''. catnla nuclei caudati ; XL3, pntiimen ; ()l<\ fasciculus occi pi to-frontal is of Forel and Onufrowicz ; at. fissura coll ijcnilis ; /'»/. jiiilvinar ; 7';;. corpus fornicis : 7';//'. f'nd>ria liippocampi : IV. ventriciilus lateralis ; I'v/i/i, coriiu inferiiis ventriculi lateralis. |{. C' ciineus; 7''m, <'alcar avis ; FH. fasciculus loiifiiliidinalis inferior ; A', tissura calcarina ; (\fiTiii>), fasciculus occipito-frontalis of Fond and Onufrowic/,. forming the tapeliim of tlie cornii jiosterius ; /)«, tissura jiarieto-occipilalis ; /i'77i. nnliatio (iccipito-tlialaiiii<'a (iratioteti ; I'dc. cornii iiosleriiis ventriculi latenilis. oiioui'iNc; AND ciiAiNiNc; T(>(ji-:tiiki{ of NRUWONKS. Kick with the bundle described by Wernicke as the br.ndle from the corpus ciillosum to tlie intenuil capsuUi (Fif,'. r'' l-,<. i Mjf, Ml 1(»72 TIIK NKIlVors SYSTKM. rectus; fiirtluM', tho ji^roatcr part of the island oi' li'cil, tlio supe- rior and iiil'crior parietal lobules, the middle and inferior tem- poral eonvolutioiis exclusive of the internal temporal pole, the gyrus fusiforniis, gyrus lingualis, aiul the whole of the occipital I'm. (i75. — \'i('\v dl' hit('i;il siiiracf iiC ri;;lit ccnlniil licmi.s|ili(ii'. slinwiiif; -.ciisc cciilris mill ;issiifi;itiiiii iriil ri.s. (Al'icr 1'. I'lcilir-ij;. (Iiiiini iiiiil Sctlc. ||. Aiitl., I,ci|i/... ISitli, Till', iv, l''!?;. T. ) Tlic iiiinc iIumIv iluttril ;iri;is slmw llif rc^'iiiiis ill wliicli 111' majiirity ul' tiic stiisuiy priijirlidii iixmics tciiiiiiiiilc. Till' lariit' |Hirlii)iis hctwct'ii llic (luttcil arciis itiu-cm'IiI tlicassiiciatioTi criitn's. lobe not included in the visual sense .irea. In the diagram these relations are shown very clearly (l''ig^. 0I.*» and Glti). The sense areas are dotted, the regions in which the majority ol' the sensory fibres terminate iieing closely studded with dots, while in between the ditl'erent sense areas the largo undotteil regions correspond to the |)ortions of the cortex entirely devoid of projection fibres, or at most })rovided with extremely few of smdi lil)res. At the periphery of each sense area is a marginal zone in whiidi pro- jection fibres are less thickly distributed. The white matter corresponding to all the cortical regions be- tween the sense areas, with the exception, perhaps, of that beneatli the angular gyrus, becomes medullated considerably later than that of the sense centres, so that, even in children three months old, the former are sharply distinguisliable from the latter by their I ^ €■ GUOUI'ING AN!) CIIAIXINO T«»(iKTI!KIl OF N'KIIUOXKS. loj.'i lIiosc souse sorv IWCfll nil to .'s, t>r the pro- is bc- \i':Uli than OIllllS thi'ir poverty in niyoliii. Kk<'lisig finds, howovor, that inoduHatctl paths ^a-adually ^row ont from the sense centres into these non-rnedul- lated regions. Further, between the individual gyri of the non- nieduUated regions, bajids of association lil)res gradually ripen, con- necting the individual gyri with others near them and also with gyri at a distance, iiy means of the corpus callosuni tlie gyri in one hemisphere arc connected with those of the opposite hemisphere. Flechsig, on account of the marked predominance of association systems in these areas, has designated them " association ctentres of the cerebral cortex."* He docs not, as did Meynert, believe Fio. Cui). — View of the iiiicli;il smiUcc nl' the lift ciTchnil ln'iiiisiilific. slmwiiis; sense centres and associaliun cenlies. ( Alter P. I^'leelisi-j. ( ieliiin nnd Seele, II. Antl., licip/., lS!l(i. Till', iv. Fi;;. S. ) /, e'liMus inaniniill:ire ; .', meiliau section el' eliiasnia dplicinn ; .;. ccpniniissuni anterim cerelni : J. cidlicnlns snperior; .■>, eiirpns callnsnni ; t!, lorni.x ; 7. septum p( lliiciduin : :. cnipus pineale; 7/.S teninentiun : 7', basis pedniwuli. that the individual sense centres are connected directly with one another, but thinks that, on the contrary, they are connected rather indirectly by means of the association centres. The lat- * It is surprising to fuid how eldscly many <>f tlie views recently expressed by Fleclisig accdnl with some ol' the duelrinus prouiulguted by llie Kngllsli neurok^gist Hroadbcnt. I. I •::. ^ '' i t. '% 1 r I I i : ,i', 1 Jf '«i 1 t'.' ii ¥ [ .- ■ . !''...■■ 1 i?n :, ■J074- TIIK XEHVOUS SYSTKM. H Sji^ Mo ter, receiving conduction librcs from luljuLont .?ense centres luul from ;uljiu;ent us well as distant association cei^tres, furnish an anatomical mechaiiisni which makes jwssible ^he w.*;"king up into higher units of simple sense impressions and of combinations of simple sense impressions of the same (piality and of dilTerent qualities. Tlius Ficchsig denies tlie function ascribed by many to the so-called fasciculus longitudinalis inferior which would make it a system associating directly two sense centres with one another. He thinks that, on the contrary, it has an entirely diiferent signiticance, which, however, I shall not discuss at this time. The position of the individual areas of association probably throws some light upon the functions which they subserve (Figs. 675 and (570). Thus the large region which Flechsig designates as the posterior large association centre and which includes the prjecuneus, all the parietal gyri except the posterior central gyrus, part of the gyrus lingualis, the fusiform gyrus, and the middle and inferior temporal gyri, as well as all portions of the occipital gyri not concerned in the visual sense area, is situated between the visual, the soniiwsthetic, and the auditory sense areas. Tiie island of Heil is surrounded by the somt\3sthetic area, the auditory area, and the olfactory area, and into it run bands of fibres from these seJise areas, so that it, Flechsig thinks, is properly designated as the middle association centre. The main portion of the frontal lobe, Flechsig's anterior association centre, is very intimately con- nected with the soma^sthetic area, and with the olfactory sense area.* While the anatomical evidence which Flechsig has hrought forward would seem to be sufficient to indicate in general the essential nature of the functions of the different regions of the cortex described, there has been already collected a mass of clin- ical and pathological data which, when reviewed in the light of the newer anatomical knowledge, affords confirmatory proof of his views. Lesions involving the sense centres are followed by a train of symptons of an entirely different character from those which accompany lesions of the association centres. This will be clear if certain familiar examples be recalled. All the evi- * As Flechsig renuirks, however, it is not probable that its function is confined to t!.e association of olfactory impressions with sensations wliich tell us alioiit the condition of our bodies, for the olfactory sense in man is relatively little developed, while the frontal lobo is developed ad muximum. Gltori'lNli AND CIIAINIXG TOOETHER OF XKUUONES. 1»»75 donee goes to show that tlio plicnonuMiu of shiir|i, <'h'iiii-oiit jicii- siitions us they appear in I'onscioiisness liave tlieir origin in tlie sense centres. As a resnlt of a lesion of a given sense centre this shar})nes8 of sensation for the particuhir sense (|uality conci'med disappears. If tlie visual area on hoth sides of the brain be de- stroyed, the patient no longer sees, lie may oecasionally believe that he still possesses visual sensation, but on closer exaiuitiation it will be found that the picture in his consciousness is a ineniorv- picture, not a perception. Patients sulTering from double-sided destruction of the auditory sense area are absolutely deaf,* and it is to bo imagined that if both soma'sthetic ureas were entirely destroyed the individual wouM, if he continued to live at all, be deprived of sensations informing him of the condition of his body, of the skin, and of the visceru.f Injury to the central gvri on the left side about their middle has been followed by loss of power to recognize correctly the form of a given object when the right hand alone has been nsed to feel it. Irritation of the pos- terior central gyrus may lead an individual to believe tliat he experiences movements of his thumb even when his eyes convince him that it has not moved. Tumors pressing upon the olfactory sense area have given rise to subje(!tive odors, while mental images of colored figures aiul the like have occurred in individuals in whom after death cysts involving the visual area of the occipital lobe have been found. Irritative lesions of the auditory sense area can give rise to noises and to other sound-images. Destruc- tion of the sejise centre concerned witli the sensations of any given sense quality is associated with the so-called perceptive sensory disturbances. The sense centres are concerned not only in the bringing into consciousness of the individual elementary sense impressions, but ttio distinction of the spatial and temporal relations of these impressions, if Flechsig be right, is also to be attributed to the ., \ F- i *Cf. a very imiiortiint rase desoribod hy Frii'dliiiKlcr, (\, ami V. Wcrnitke. Kin Fall von Taiihlicil infoljje doppolscitiger Liision des Sfliliifolaiipens. Fortschr. d. :\Ied.. I5d. i (lHS;i). + For evidence as to the paramount importance of the soma'sthetic area for the development of a personality, the reader is referred to the thoroujjh studies which were made of the brain of Lanra l{ridi,nnan. Cf. Donaldson, 11. II. Anatomical Observations on the Hrain and Several Sense Orj;aiis of the Blind Deaf-Mule, Laura Dewey IJridgman. Am. J. Psyehul., vol. iii (IKUO), pp. '.>'j;J-;542. i >: :• n ir ) ■: iiiit I /'! 1<»7«I Till-; NKIiVol'S SYSTEM. li '<: I 1 (i'5, activities of ilic cortical hciiso mijIutcs. 'I'iius " percoptivo word- ileurnoss" has been shown todopeiul, in rigiit-liundod individuals, upon disease of the left auditory sense area. Wlien words are spoken the individual hears only confused noises ajid does not understand them. Wernicke believed tiuit in such cases there is a permanent loss of the memory i)ictures of the sounds of words. This is denied by Flechsig, who holds that here we have to deal rather with an incajjacuty of separating the sounds which follow one another in the spoken words, of distinguishing tone intervals correctly between syllabic.-; and words. The patient does not perceive an orderly combination of sounds, but an undecipher- able chaos of tones and noises. If in such cases we have to deal with ])ure lesions of the auditory sense area the patients can speak spontaneously a large number of words correi^tly, so that the ordinary observer miglit scarcely notice any ilisturbance in his speech, a fact which makes it seem likely that the memory pictures of the sounds of words have been retained in spite of the destruction of the auditory sense area. On the other hand, if the ])eriphery of the auditory sense area bo destroyed, as in Heubner's well-known case, aiul the auditory sense area itself remain uninjured, the clinical picture is exactly reversed; the patient in this transcortical sensory aphasia (in the sense of Lichtbeim and Wernicke) can speak spontaiUM)Usly only very few words (amiu'sic ai»hasia), or there exists a high degree of para- phasia. The patient, however, can from the beginning repeat correctly words which arc spoken before him, which is evidence in favor of the view that he has heard the words correctly and has retained the capacity for perceiving corri'ctly the intervals between syllables and words. If, in spite of this, word -deafness exists, the reason, perhaps, lies in the fact that the words cor- rectly heard do not call forth by association into consciousness the memory pictures which belong to them, and which help to make up the sense (" ai)])erceptive word-deafness " of Herbart). Of course, these forms are seldom met with pure, for in the majority of cases the auditory sense area and its periphery are diseased more or less together, and mixed forms are of no nse for the decision of the cpiestion whether and in how far diseases of the auditory sense area alone have disturbances of memory as a result. If the cortical form of " ])erceptive word-deafness " does not depend on the loss of memory pictures of the sounds of words r.UOUPINd AND CIIAIMNO TOCIKTliEU OF NKUIlONKS. |o i i iini- H'ilt nco antl Vills ncss ■or- sm-HS ) to ,rt). the are 10 for es of as a not ifords ; it is liiglily i)rohiil)lc that it is a " sonsory atactic" (listiirhaiice — tho toiiiporai arraiigciiiciit of the auditory sensations is laci\inj^. If Flcchsig bo corrci't about this, tho essential basis for spatial and temporal i)orceptions is to bo sought in the sense spheres. Klechsig thinks that the tactile disturbance, described by Wernicke, associated with disease of the soiuicsthetic area, is due to loss of the capacity of nniling i)roperly tactile stimuli to a mental image (that is to say, the spatial arrangement of the single impressions is no longer i)0ssible). It is rather an atactic disturbance of perce])ri(tn than, as Wernicke thinks, a defect of menu)ry cajjatnty. It is cpiite analogous to the perceptive word- deafness dependent upon lesion of the auditrtry sense area, it is probable that the organic traces of the more extensive memory pictures, built up of no matter what sense qualities, are associated with the cells of the association centres which lie between the sense centres. Before passing to the descrijjtion of the functions of the as- sociation centres, however, a few special points in connection with the sense centres must be considered. With regard to tho soniu'sthetic area it has long been known that disease of the central jonvohuions is accoini)anied frcxact locali- zation. As a result of lesion of the arn) region there is an in- capacity to recognize external objects by feeling their form. In- deed, these disturbances of the stcreognostic sense seem to be characteristic of c(>rtical lesions. If the inferior frontal convolution be di.seased, tlie capacity for calling up images of movements, or rather tho capacity to feel the position of the organs which particijiate in speech, suffers, so that sensory system Xo. 3, c(mnected with the inferior frontal gyrus, is accordingly not ditferent in the sensation (|uality medi- ated from the sensory paths of the central gyri, but simply in re- gard to the region of the body whence the sensations come ; the newborn infant, for ])urposes of self-])reservation, makes use far earlier of his extremities, his lips and his tongue, than of his trunk and s]ieech muscles, and this fact of experience agrees ex- tremely well with the developmental finding that the sensory a IV '■: .1 i \ J * VW't ^ I u 107S Till-; NKKVors SYSTKM. I' '1 iiiid motor j)iitli.s of tlii" cxIrcMuitioa (lovelop carlior tlmn thoso for tho trunk and tlio sjit'ciul or<,'ims of Hptrch ( Flcclisi},'). Certain of tlio fibres of system No. 'Z Imvo Hppari'Utly to do with miiscie sense, Imt our lvno\vI('(l<,'e is as yet insiinicieiit concerniii',' tliis gnmi). 'riierc is a good deal of eviden-e, too, tiiat tlie sonia^stiict io urea plays an important jtart in the coming into eonsciousness of many of the hodily processes aeeomjtanying or constituting tho emotions, and that tlicnce start out nuiiiy of the movements which serve as tht; expression of tlie emotions, a i)oint of view wliich, if conlirmed, is of intinito importance for psychiatry. Let U8 now turn to the subject of tho functional activities of tho association centres. We have seen before that from the anatomical arrangement these areas apjjcar to f xist for tlic pur- pose of uniting the activities of the various sense centres. C'lini- cal and pathological evidence, too, is in favor of Flechsig's view that they are concerned in the higher numifestations of the in- tellect, in the processes of memory, recognition, judgment and rellection. It is in disease of these areas that we see, above all, disturbances of memory and of the associative j)rocesses. When the posterior large Association centre, for example, is diseased, the lesions are not accompanied with phenomeiui of perceptive deafness, of j)erceptive blindness, or of perceptive tactile ana's- thesia, providing the ailjoining sense centres remain unaffected. But instead of these an entirely dilTerent group of clinical }/he- nomena becomes manifest. Here we meet sometiines with the conditions known as mind-blindness, mind-deafness, and the like; with ajmixia or agnosia; sometimes there is weakening of the power of visual imagination. 'J'here may be an iiica])acity to call into consciousness melodies which the individual formerly knew well, and in lesions of this area on the left side in certain portions, sensory (optic) alexia, optic aphasia (amnesic color-blindness), apperceptive (transcortical) word-deafness, verbal paraphasia, and sensory amnesic aphasia (inca{)acity to call up the memories of the sounds of words correspording to the mental images in con- sciousness). The memory capacity may in such instances be af- fected apparently in either or both of two ways — (1) by destruc- tion of the association paths concerned in setting free given mental images, and (2) by actual, permanent destruction of the organic memory traces in the nerve cells. It wonld appear, therefore, that the posterior large association centre is concerned in the formation and collection of ideas concerning the external GUOl'IMNHJ AND C'lIAIN'INd TO(JKTIIKU OV NKURONKS. lu7«J world — tliiit !s, of iicliial kiiowlcd;^!' t'oiicfniiiig external objects, of ('oiiil)iii!iti(, 54. Anaxiinander, 220. Anderson, II. K., 44]. Andriezen, L., 29, 979, 6(J3. Apathy, S., 38, 47, i)2, 23, M, 24 25 rp'' A'' J:'' ■^' ''''"'• -»'»<>•«''.' 62, 63,6,, 70, 73, 96, 13(i, 137, 138 07' ■3, 359, 140, 156, 265, 271, 2/2. 896. Argutinsky. P., 888, 668. Arndt, K.. 104, 655. Arnold, .1., 667. 1044. 1058. Arnstein, C, 33. 374, 277, 421, 530 Auerbaeh, L.. 78, 82, 191, 593, 602, Aycrs, II., 499. Azoulay. 206, 350, 666. Baas, K., 832. Babes, V., 25, 289. Babinski, 413. Bat'oii. Francis, 274, Bner. K. E. von, 193, 790. Raer. W. S.. 245, 246. Baginski, R.. 504, 836, 852. Baillargor, 821. Baker. Prank. 10. Balfour, R M., 179^ ^o]. Ballet. O., 151, 238, 289, 1065. Baj-bacc.i,0.,.w,, 441, 442, 446,452, ^ 5^9 '"' ^''"''"^'' ^'•' ^^' '*=^' '^^'253, Hartholow, R., 1002. Iksilewski, A., 960, 614, 615, 967, •MO. Bastian, 442, 1077. Batten, F. E., 418. Raumgarten, P., 786, 792 Beale, 102. Beard, J., 179,200. Reehterew. W. von, 28, 13, 82 46 268, 270, 319. 424, 427. 428 '429 430, 473, 501, 5u4, 505, 509, 511 523* 34{), 529. 565, 569, 570, 382 '577' 386,592, 605,608, 609, 401 ' 612* 402, 613, 614, 403, 4oi, 618 63o' f 2, 635. 424, 655, 658, 431 659 432, 664, 684, 688, 446, 692, 694; ^00. -05. 456, 708, 715, 716, 805 ««^^^~oY'^^'^'^'^^«'«43,852,864; 865,872.888,954,609,956,957 958 »60;«66,614,615,967.'968,'9 4 «5J0. 1020,1047,1063,670. Rt'ck. A.. 289. Rfcker, 96, 137. Beevor, C. E.. 346. 995, 996 632 1000, 1001, ,003. 635 636 63^' 1007,1008,639,1063. ' Bell. Sir Charles, 3, 897. Bellonci. G.. 831. Benirnelen, J. F. van. 201 Bi'rard, 229. 1085 mB' f ii::ii / -I 1()8<5 THE NKRVOUS SYSTP]*!. u Bcrdcz, 441. Herger, II., 94. Hergiimnn, G. IT., 840. Berkley, II. L., 10, 11, 29, 37, 88, 71, 76, 3«, 230, 153, 154, 285, 288, :W 1.402, 411. 418, 8!>2. HernluniiKM-, S., 2;i5, 911, 942, 045, 94G. 050. Bert. 1'., 000. Bethe. A., 34, 36, 37, 38, 46, 96, 137, 138, 130, 145, 153, 2(55. 271. 272, 1«2. 273, 316, 213. 305, 366, 368, 219, 474. Bettmann, M., 120. Betz, 108, 112, 135, 078. Biniielii, 1080. Biedcrmann, \V., SO, 060, 065, 613, OOC). 068, 973 Biedl. .\., 231, 235.060, 965, fil3, 066. 968. 073. Bielsehowsky. .M., 705. 717. Biesiadecki. A. von, 788. Bignami. A.. 590. Bind.-4. 265. 266, 267. 410, 411. (Magiinski. A.. (110. Glarke. II., 078. ("larkc. .1. liockhart. 172, 403, 474, 504. 576. 581, 851, 913. Goen, 24(». Golmheim. J., 214, 302. Golc. 921. Golent)ninder, 911. Gollins, J., 905. 010. Corning, 019, 589. 591. }■ .: :-t INDEX OF AUTHORS. 1087 Corti, 112. r)4r).54«. HUG. 8:J0. Cox, VV. FI.. 10. ("rumor. A., 21»0. 505, 51S, 569, 651, 664, 716, mo. ('nivt>illiiiT. 2'i'X C'liccuti, (i., 381, 111. ("iishing, Harvey VV., 339. t'zokor, 368. D'Abundo. 402. Dana, ('. L.. 339. 340, 341, 107. lt)S. l))irksclic\vilsi-li, I.. (»., 'J31, 300, ."iOD. 614, 618. 716, 719, 721. 724, 725. K05. 831.917. 944. 945. Darwin, t'liarlcs, 76. Daviilc.ff, M. v(in. ;l(»2. Dawson, I*. M.. 245. Haxenbcrgcr. II., 450, 452, Deiin, .lolin, 504, 851. Dc-avcr, .1. 1$., 1002. Di'cn, Van. 897. Dees, O.. 623. Di'liio, 288. Di'lilcr. 148. Deiters, O. F. C, 4, 1, 5, 12, 102, 122, 131. .504, 505. ■07, 508, 509. 511. 512, .523, 508. 575. 030. 631, 632, 63(1. 637, 638. 849. 960, 964. 965. 96(). 967. 968. Dojerint'. .(.. 289, 290, 442, Ar>x. 655, 668, 674, 44ri, 705, 707, 71fl, 731, 732. 511, «38. 1044. 1046, 1047, 10.59, ({(;S. 1061. 1062. HM). 1062. (J71,«72, 1067,074, 106!*, 673. Dejerinc, Mnie. .!., 70,5, 707, 717, 731, 732. Deiuoor, L.. 418. DeQuervain, Fritz, 111.290. Dcrfuin. F. X.. 832. De Will. Lyilia, 417, 275. 419. 270. 27S. DextiT. Franklin, 175. Dii-kinson, 229. Diolitnii. 220. Dij^se, ,T., 18 i, ,526. Dixon. A. F.. ,525. Dniitrijewski, P., 2a(J, 382. Do-jit'l. A. S.. 34. 36. 37, 105, 141, 145. 184, 115, 18.5, 11«. 262, 365. 21(5. 21 7. 218. 37(1. 240. 241. 386, 243, 244, 388, 390. 393. 252, 394. 253, 400. 261>. 2<)0. 2({1, 2(J2, 418, 421. .534. .540, 897. DoKicl, .1., 418. Dohrn. A., 170. 19.5.201. DoniiUlson, U. 11.. 42. 80, 251, 275, .531. 1075. Donilers, F, (' ,835. Driescli, 221. I»ii lU.is-Keyniond. E.. 2.52. I)iil:.nr. 4,50. 457, 4.58. Duret, 1014. Diitil. A.. 151.238, 290. Duval, .M., 100. 942, 947. Fhbinfiliansi. 835. Kberslaller, 754. Kberth, 365. Iv'khanlt. ('.. 330. Kdinger. L., 10, 29, 38, 44, 254, 316, 463, 523, 565, 569, 590, 598, 599, 664. 715. 748. 764, 766. 4S9, 775, 500. 804. 902, 903, 933, 942, 944, 945, 1056, 1058. {•'luvnberg. 3. Klirlicli, l'.,31, 32, 33, 36, 37. 47. 67, 101, 127, 128, 186, 241, 365, 394, 402.411.4,59,530.897. Fiscnlolir. 413. Fisler, P.. 19.5, 18(;, 187. Kinniort, 3. Fngehnann. 142, 157, 359. Ei-b, 244, 899. Frlanger. ,1., 1.50, 237, 295. 17(), 308, 911. Eve, F. C, 278. Fwart,921. Kwing, ,)., 289. Exner. S.. 252. Firricr. D.. 565. 570. 572. 383. 573, 3S4. 385, 580, 304, 655, 708. 717, 823, 899, 900, 9(i4, 973, 994, 995, 996. 997. 1000. 1028. 1047, 1055. Fieschi, D., 246. Fisclu-r. A.. 131, 141. Fish, P. A., 43. I 1088 TIIK NKKVOUS SYSTEM. Platan, K., 2;J1, 2;{5, 14», 277, 280, 285,286,28)). 174, 1 7S, HOI, 17«, 302, ISO, I HI, l.s'i, :{()(;. ;{08, :no, 450. 458, i)ll, !)14, i)5;J, lOO'J. (}40. Fh'disig. P.. 25. 44, 87, 8!), })2, 244. 25(5, 2(i5, :iU\, 424, 425, •_»«(), 427, 428, 429. '_»S1, 2M2, 4;{0, 4;J0. 452, 45;j. 458. 4(11, 4(i:i, 47:5. 504, 505, 50!), 50:{, 5(i8, 575, 577, 581, 58;{, 389. 391 , 5!)2. 5!);{. 598, 605, 608, 60!), 614, 647. 657, 667, 681. 684, 685, 686, 688, (18!). 607. 6!)!», 700, 702, 70:), 704, 705, 707. 714. 715, 721. 7:iO. 7;n, Vi'.i, T-i4, 4(W, 7.'}6. 4(J7, 4({H, 7;i8, 75;3, 75!). 772. 806. 816. .jL'o, 822, 823, f^O, 836. 837. 843, 852, 875. 876, SiJl, 878, 963, 974, !)76, !)80, «25, 986, 987, «2«. ($27, (;2K, «2«. 991. «30, 992. (531, 993, 1010, 1020. 1021, 1040, 1045, 1047, 1065. 1070, 1071, «7r>. 1073. ({7«, 1074, 1075, 1076, 1077, 1078, 1079, 1081, 1082, 1083. Fleming, H. A.. 232. Plemmiug, W., 104, 105, «3, 113, 135, 141, 145, 154. 156. 281. Flesch, M., 123. Flexiier, Simon. 247, 297. Fcerster, 826, 828. Forel, A., 9. 15. 17. 18, 20, 22, 26, 231, 651, 653, 655. 657. 668. 435. 670. 43«, 671, 672, 437, 673, 43H, 674, 675, 682. 684, 685, 686, 692, 704, 727, 730, 731, 732, 772. 798. 805. 812, 836, 841, 873. 971, 1067, 073, 1067. Forgue, K., 900. P'orster. Lanra. 412, 413, 414. Foster, M., 86. 554. 963, 965. Fraenkel, 413. Franck, F.. !)83, 1003, 1022. Francke, C, 42. Francotte, 591. Frankl-Hochwart, 747. Franklin. Mvs. Cliristine Ijadd, 835. Prenil, S., 569. 716. Fioy, M. von, 253, 255, 330, 372, 392. Fricillaendv". ('., 229, 1075. Friedinann, }l.., 290. Fritsch, (J., 994. Kroinnmnn, 102, 154. Fn.ri.'i). 350, 927. Kliil Hinder. M.. 195, 920. Fiirstncr, 983. Fiisari. 962. (iad, .1.. 235, 2ii8, 100!), «4(K (JaliM.Iti, (J.. 141. (ianscr. S.. 668, 761, 767, 768, 784, 788, .'>0(5, 798. 807. (iardincr. 7. (lawkell. 888. (}(>l)erg. A.. 370. 223, 224. (iel.iniid. P., 716. (iogonbanr. 1!)5, !•!!». 921. (iciiuclitcn. .\. van. 9, 't, l.'i. 2!t. 45, 31. 34. 4S. :,.-». 142, 144, 171. I82! 110. 114. 1H4. 254. 260. 261. 262. l.'iS. 266. 270, 2!)!). 30!). 194. 19.'), 19«, 2i:». 365, 374, 375, 292, 465! 467. 303. 304. 49!). lOO. 514. 342. 523. 530. 546, 606, 6 IS, 650, 673, 675, 454, 721, 725, 775, 803, 826. .i3o! 832. SH5. !tl4. !t2(i. 932, 599, !)42, !)45. (J05, <{24. 985. Gennari, 821. 1058. (Jorhifh, J. von, 5, 2, 6, 7. 13, 42, 60, 463, 884. (iiose, 450. (iicson. Ira van. 108. 110. 142. 1.55, 239, 522. (iilbert, 229. (iildcr.slcL've, Basil L., 40, 667. Oocppert, 38. (ioi'tlic, .lohann Wolfgang von, 221. Goldsclu'idcr, A.. 251, 253, 255, 277, 280, 285, 286. 28!). 1 7S. 301. I79! 302. 1S(K ISI. 1S2, 307, 308, 3()!». 330. ({ojgi, (".. 9. 10. 11. 12. 13. 14. 15, 17, 18, 21, 22, 25. 26. 28. 29, 3(i. 37, 42, 47, 48. 50, 63. 64. (i7. 68, 75. 76, 78. 79. 80. 81. 82. 84. 90. !)3. !)4. !)(!. !)8. 101. 115. 13!). 140, 7.S, 1.50, S5, 152. 153. 172. 184. 239, 240, 257, 258, 25!). 261. 265. 270, 317, 365, :i70, 374. 376. 378, .•!86. 392. 394. 396. 402, 2(53, 405, 409, 410, 411, 424, 430, IXr)R\' OF AUTflOFfS. 457, 450. m, m, 4fi5, 4«(( 407 40H.47O.47;(.5ll,r,|H.5^>0,5;]O.5:{|' •»;K 5H(). «;{a, (i;i,i. (j;{7, «r,!<, «(i4 m: "H7H.,7:>5.7;W.7«H.775,7H4:7i*r hoo.ho;j,si2,hi';{,h;w.n40,84;}h5->' »;;^ !.47,»5.>,!«i,s. !,:,.!,:«, »;„,,,H„; io;i;i, io;j4. io;m, 105;] Ooll 24,424,425, 427, 428, 489, 430. 4S.i, 435, 4:)«l, 439, 504, 705. (roller. A., 835. Goltz, 705. Ooinlmull, A., 442, 450. 452, 453 454 450.458,401. Ootch, K, 274. (iowcrs, VV. U.. 45. 589, 590 rm V)-> 593,594, 598, 599, 00 1, 002. (i04 (!(»5 649, 740, 780, 900, 972, 973, 'lo;j7' 1039. ' .>., 872, 570, 947. «0(;. 950 !)0y «1«. 972. • H''lmlioliz. jr.. .3. 7«7, a3.j. Hclwe^r, 9.54, 957.95s H^de,. 1^:^340. 372: 373. 374. 375. •j^<>. .J<7. 787, 790. 50{). 524. 89(i, Henri, 330. H.>ns,.|,en, .S. F.. 717, 793, 820, 827 828, 832. • Hensen, V.. 949. Hcraclitus. 220. Herbart. 1070. Heibst. G.. 221. 393. Hciiii-r, E.. 83.5. Hermaiiii. 347. Herreidieiser. 793. H.Tri,.k, C. J., .5, 44, 7^1 ,)o, ^32 -.{)2. 924, 1050. ' • Hvirick, ('. L., KKTie Hen-iiiirliafii. W. P.. 332. Heiter, 241. Hertwig, O.. 0.5, 1.54, 125. Hess, P.. 289. Heubiier, U)7(). m I SI r> i I i 1()S)U TIIK NKIfVoUS SYSTEM. ncwcisoii. .i,,iiii. .'tos.itoo. :no. .*ti i. .'{ I '.'. :i 1 11 :i 1 1, .{ I ;,. .{ i «. .{ i ; .{ i h. a I U. :{'_'o. :{•.» 1 . :{i'2, :{•_»:{, ;{24. ;{•_»«. a 7s. .{SO. :{s I , UK,, 1 1 4. u :>. 4 1 IJ. I/qiiifiil<>. -lOO. Jackson. ■!. lliiKliliiiKS OH^. Omt. .liMohi. M. I'.. I(»h:{. ■t20.4L»«. 427,4:{0, 447. 44.S, 441», | .lacdl.M.lm. L.. 2H(), 7H((. 4.-.1!. 4r>:{. 4«5I. 4(J1V 4«:{. 5a7. .'.:»M, I .lacciiics. I'.. 403, 411). Mil .'».V_', :»S».'». .-»«MJ. .-,«»7, r.(M. «0'-'. Iiikol.. ('.. 70.1 <>o:t.. itiit. jh). 1M,{)2. HM. »:i. »4. Hi.-). UiO, {>.'i. 1(17. IC.H. 1(10. 17(1. 171. US, 172. KM). 102, !():{. 104. 10.-», 177. 170. 180, 181, 1h:i, ll;{. li»((, l<)4, If),-,, 212. 214. 22.V 2(;(i, 27;!. ;il7, L»OL», L'0:{. 424. aOT. ."lOl. ,-,i; i;i7. 748. 740. 7.'5(), 7.TI. 7."».j, 774. 4!)(i. 7M4. .••.S7. Kw:!. Mis. \V.,,lr., 1 1 7, l'_».% 101, .-{.W, Ml, r.l4. IFit/ijr. H.. 094. 1081. Iloili. A.. 244. 200, 201. 202. 20;5. ;{()«. Hcclic. A.. 4.')0. '-'{)({. 4r,;i. 4.')4, "it)?, '_»!)S. 4r,r.. iM)!). 4"i7. 4."i8. 4(i2. JlOl. ;J02, :{!)s, .-,os, (i()2. oi.'). n\ .Idlinslon. .1. M., 931. .losrph. 2."i8. .Icwctl, M.. 220, .luliuslturgtT, 200. Ka.'s. 'I'., 1070. KalilcT. <).. 439. 048. Kaiser, (>.. HH4. 88.',, 00,'i. 57H. r>,SO. .'»S1, 5S2. 014. Kallius, K., 360, 368, 304, 400, 897. Kain. 1046. Kanisin. I'.. 424, 43(». Kiistner, S., 201. Kaiiriiiann. Iv, 1067. K 'en, \V. W., 1002, 1071, Kellerniiiiiii, M.. 786. Kell.v. A. (>. .1.. 43. Keiu|>iier, \V.. 301. Kerseliiier. I>., 412. 413,415. Key. I-;. A. II.. 104. Kiii,i:sl)ur.v. M. F.. 021. KliniofT. i. A.. (iO.-,. Knapii. I'. ('..34(i, 201, 349. Kiiies, 8;j'.\ Knoblauch, 983. Kocher. T.. 330. 201. Kolk. Seliroiler van , 11, 26, 28. 20. 1 4. 30. 40. ;{.'». 7M. 70. 40. 4(5. 81. .'lO. .'il, .V2. 0(». 02. .'>(5. 04. 100. 102, 143, 148, 155, 107, 10(5. 111. 2.")6. 2.18, 2.10. 261, 266, 270, 462, 463. 465. 467. 468, 474, 475, 477, 480. .501. 511, 514, 518, 523, :{.>1, 5.54. 577. 5H1. 606. 618. 621, 632. C3(J. 637, 641, 655, . I2;{, I2«, 127. I2}». 202 ;{07 ■•Wl. .VH7. !»l!(, .>S}), .-,{)0, .-,j,i. Korolow, |».. 2;{0. ;{81. Koslicwnikow. 2.(1. Ko.sscI, A.. 142. Knicppliii. !•;., 244. Kniusp, i{., .500. Krauso W.. 2W, 2m, m, m, m, '«M. 412, o4 1. 784,78.1, 8!ir,,8!»!). Kncs. ,1. von. 8;^,. Kroiniijpr, 04. KroiicnlHTrr^ f^{)~ K'i'oiillial. 1(»,-,. K'iluw, W.. 400. 412, 413. 80.-5, -.74 i'o, ■>«.>. .»7<». K'upffer. (;. von, 03, i;J6, Kir,, 910. Kusii'k, 083. lOUl lifihonlo, ,1. \'., 042, 947. Ijaiiilierl, .M., 278. Ijaiicisi, 704. Lniij,'(', 442. I'aslcd. K. I-;., 288. Laura, .184. liavdowsky, 30. lA'aiiiiiif,', io, lo;?;}, (jjo. Lcliniii, 11., i,-i4. Loi.l.oss,'k, M. von, 0, 15, 21, 25 1»» 2H,20.30.37.30.«2.73.74.3«,70; *». «1. !'(>. !»l. .-,.V 02. 03, r,7 04 10.-5. ioo.«i. no, in, no,,.. \^.; '•■'". 1-!'. 148, .s4. \r,r,. 101 no" low, 1«4. 188, 2«, 258, 200 "0"' 265, 206. 267. 200. 270. l«l' ;507' •'508. 300. 310. 358, 2(M>. 210 43o" 446. 450. 458, 450, 403. 405," 407' rm, 470. 471, 472. 30({. 473 474' 475. .500, ;{•{.•{, ;{.{},, .^o,; ,-,o~ .j^^" 543. mi ;{<};{, .582, .{,^,s(. .r-,oo, (io',," 400, 885, 5({7, 887, 005, 085 Ki'onowa. ( ». v.„i. 179,785,883. ''•'t>iif,'(', On;!. l-ciilic, W., 040. ''«'vi, (}.. 143. ficwis, Mcvan. 201. 078. I'i'wis, .Maryiiivt. 140. I'nwis, Morris .J.. ioo;{. Lfvilcn. K.. 8;i2. '^'■.vihV, F.. K»2, 147. 273. Liclillifini, 1070. liiliciifrl.l, l.'{2, 133. lAss,uu-v. 11.. 423. 425.427,430. 435 430.400.408.474. ''loyl. •(. II.. 1002. Lucy. W. A.. 105. I'ocb, .h, 331, 347. 310. Iin(.w..til),al, \., 444, 503^ g^o ^jg !»'")7. Ofi.l. OO.',. !»70. ' ' Loid. .1. W., 203. I'ovcn, 525. liiibarscli-Ostcrlay. 104, 239. Luciani. 240, 1000. Miflcritz, ('.,884. liiidwiy. 5. I^UKaro, K.. 143. 15,3, 150. 378, 379 2H5. i72. 280. 200. .110, 1S3, 311' I S4. ;{58, 52,3. (i05. !)32 035 I^"ys. .1., 667. 671. 072. 073. 074, 680 «»4, 700. 703, 705, 707, 734 7.38' 78,3, 080. ' ^';;;;f '""• ^^- ^*- 1^2. 133. 134, sis, ^lacCallinii. ,T. n., 147. iMackcii/ii.. ,1.. ;};{o. Majjiiii, 270. •Mal.aim. A.. .580. 019,051. 6.M. 654 ^ 607. 700. 701. 707. 710. 731! -'^lall. F. P.. 178, 107. lOS, 181, 120 I ^'4. 104. 10.5. V,Ui. 204. 200 267' •■W8. 784. 701. 800, 1024. ' ' ^fallory. 04. Matidclstaimn. F.. 788. Maiicrsi. 288. Mann, (i., 08. 120, 278, 1«8, .583, 1033. ■^lann. I,., 451. Manz, 784, fi '! ^ \ I 1/ I(>i>2 TlIK NKUVOi:S SYSTKM. m ft Miirciicfi, A.. !»(HI. MiinliiiiKl. I''., 7H(i, 7»'J. Murclii'siiii, |:t(i. Mdrchi. v.. 4r», 107. ',»:;•,', 'iwr,, ',i:(h,'jji, ^'4',', 4:iH, 44:1. 444. 447, 4r.(». 4r);t. 4r.(i, 4r)H, 4r)ii, 4(ii. 4(W. 4ti;i. 51:1. 5.-,;). .'■,70, r.7:t. r.75, r)ii:>. .--(KH. r,i»4. r>!»H. -)i»!». (ioi. (i(»;i. (;i7. (|.-i4, (LV). 057, «r)l». 0(14. (1(1.*). (11)4. 7(«t. 7I',>. 7!»:!. 7!t."). MKI. 8(1. !»(i;i. !l(14. !»«"», 11(1(1, !»71.!tHr». 1014. lOKl. lO'J-i. 10'j:t. MiirKuliL's. A., 44'J, 44:i. 444. 'lU'.t. Millie, I'.. :!.*).-). 447, •_'1»4, 4."i(). 4">7. .Miiriim, A.. ^':!!». Mfiiiiicsr.., (i., 4."i, :.",'<.), ^';i(i, 14(t. I ".T •,'H!», •^>!((). •^>!).j. •,>!)!», ;t()i. ;io:.', ;to;t. iJOH, ;(oi». 4(i'j. «-,»a, ijii. Murk, K. I.., !CJ1. Murslmll, 11.'!'.. '^4.*.. Miirslmll, .iojiii, 171). Miirliii, ,!.. 2(11. Miuliii, I'., no.-.. (l.-»!). 0(14. .S4!», !»',>7. Miirtiiiolli, ('., l.'i;(, !i7(i. iMiiSL'lli, K., 28H. Miisius, Jean. iiT. Miiycr, C. ;J4, 442. 717. Miiycr. P., 201. Mayspr, 2:{1. Miizzoni, ;i'J2. :{00. 411. McCliirc, ('. F. W.. 140, Moder, E., 717. Mcissn.«r, (J., 7H. H2, 1!)1. 225, 384, 380, ;}'J0. ;«»2. Melkicli, 411, L»;o. Melius. K. L.. 107, !)«:;, 102:!, 1024, (J45, (»4(.. 047. «4S. MU. 102K. «."»(>. 05 1, 101)0. (►:>'.'. (;:»». 1032. «r>4. lo.V). Mendel, K., 2;}l. 004, 831, mO. Moiiidiiv. 024. Mcnzcl, O.'iS. Merke!, P., ISS, 300. 300, 307, 308. 309, 374, 377. 384, .".41. 8.-).'). i»3.s. Merkid-lJoniift. 12. 104. 300, 424. Meyer. A.. 1.5.1. 781, (}22, lO.'iS, lO.JO. Miner, ("., 443. Meyer, l\, 710. !».-.4. Meyer, S., .'i4r>. 857. Muynert. 'I'.. 42. !)8, .WJ, ««7. 008, 070, 072. (iM.V OHl). 713, 714. 71.5, 72.5, 732, 741, 772, 775, 777, 7n3, 80.5, H12,H0H, 873, 1)71, 10.5H. 1008. Michel,.!, von. 7HN, 7Ni), 71)1. Miiialkovies, Vom. 71(0. Miiloii, 132. Mills, ('. K., 161.008, 103», 1047. Minpizzini, (i., 47.5, 0.54, 717, 731. MiiK.t, ('. S., 40, 104, 748. Mirlo. 0.57. Mislawsky, N., 207. Misslawsky, 014, MohiiLS 1'. .!., 244. Moeli, ('.. 083, 1022. Monakow, C. von, IH, 2H, 44, .504, .580, .588. 0.50, 051, 057, 007, 008. 074, 07!), 080. 081. 44i>. 0H2, 441, 442, 0H,5, 444, OHO, 08!). 0!)3, (li)7, 0!)8, 700, 701, 702, 707, 710, 727, 730. 731, 708, 7H4, 7H.5, 7i)8, .'»I0, NOO. 802. 814, .'>l!l. 81.5, .'>22, .',2:{, HI 7, .V_M{, 822, 823, .'i'i», H20, 827. :>;U, :»:{2, 830, H33, 830, 837, 841. :»4(», 84!>, 852, 853, 801, .'i.-iO, 802, H08, 873, .'».'>», 87.5. .■>«4. 881. !)49, !)74, 1012, (541, <}42, 1022, 10.34, 1030, (S(U», ({«!, 1044, 104.5, 1040, 104H. 1052. 1081, 1082. Mondino. 240. .Monro. 774. Montjjoniery. T. 11.. 145. Monti, A., 71, 132, 152, 230, 240,285, 200. Morfjenstern, M., 37!), 381. Morill, A. I)., 30. Mott. !'. \V.. 251, 200, 441, 444. 403, 570. 574. .580, .583, 500, 3!).), »{Mi, .504, 5!)8, 509, 000.001, 002, 701, 717, 888. 083. .Moiirek, J., 288. :Miiir, H., 4,50. 4.58. 401. Midler, K., 104, 2;$!, 382,402. Miiller, K., 717. Midler, (J. K., 8.i.5. Midler, lie. .ivdi, 10,443. :\I idler, .lohanneN 2.5.5, 787, 897. Mailer, Wilheiin, 537,530. te. INDKX <)|.' AirrjIOUs. Mwnk. II.. 2;{o 007 ,.,,3 . KHM). km:. ' ' Al'inx,..,-. K.. 04,^ j,»2. -J:J». -in 4.i;{ •J-l!*. .'100. r.TO. r,H(). 717, 7H(| 7i,,'i ' .Mi.nilu/r. W., iwj, loj;,, i,,.-,.-,^ ,„«„ 1 (»!»;{ Niljjoli, (ID. I, '54. NlW'llc, .1., -IfJ, .}4;j Xanirclo. <■. M.. ioqjj. Xiiiisi-n. K. 17, 147. ar,7. Xassc. 'i2',i. Neiil, II. v., lur, ^(•\nH!). Nicimii'k, .*J»ir(. ^i«sl, F..45.(io,07.!m.!,7.;iJ».!,H.| «l. 104, lOr,. l(),i, 107. lOH, M,!, , '"•"•'•"■•. "6. 07, IIT.Os'li «». Il!», 70, 71, ,^„, |:>l 7..',. |2;UH11>.1, 12T,iaf<.I..}U.To i;i ia4. l.T,, i;{G, l.-JH, |;t!,, ,4,, s; n ">«, ''•7,~':il,:.';{;u';{4,;>;jr,.'o;(H'>;{ 3-12.-4r,,2HO.J«l.oHo.o„.,. „.„;:„ i<0, mi. 171, of^7, .)(,! .,(,., .„^ 2M.a!)7.l'!)!..;i02,;io;{,;iO(UjOM ;7| ••ir.H. (;•,';{. (i;io, 007. ,.;,. ,j-. ^j,^ ^.^, 6H0.80H.H7r..H88,:,({5),!,io,yii .,1. U2U, !»r)0. N"Uiimf,'el, II., 747, 1013, N'ottlidft. A. von. ','27. N'lisslmimi, 4G, 195. Oborstoinor, IT., 108, 4.'51, 453, 4(5] 51H, r,2',i, as 7. 300. (il4. «;J3 804 0;50. !)33, 942, 947. Oddi, K.. 441,444. Omifn.wicz, M., 502. 8;i«, 84J, 10(i7. 07;{. ' >rrii, K., ;}76. Osborn, II. p.. lo.^e. Osier, William. 100. 2()0, 1039. O.slroiuiiow, P.. 2'2S. 377. <»ttoleiiglii, I)., 290. Ow.siannikow, P., 360. I'aeini, 390, 393. l*al, 34. I'aliiiliin). (J., 444. IVuidi. K., 288. I'uiii//a, M., 897, 900. '''il<'i««.n, A. M., 195, 201, 338 ''"''•'•'••<. Mi.;,'l, T.. 4(12, 584. 589. 594 •J»7, (101, ((03. • IVIiicz. I'. I,., 4«.'}. I't'iiizzi, (f. |{., 444, IV'rciii, 830. ''•'rgcn.s, K.. 280. l' I'ienvt, 428, 473, 1012. I'ilcz, 108. I'iiikiis. 921. I'ilri's, A.. 983. 1003, 1022. ''Iati>. 47, 220. ''lall, .Jiilid M., 1!),-,, ''"Hack. M.. 301. I'-'pofl". N'., 246. 290. I'liliylkow. (i., 805. IVnat, ('. A., 278. '•'"•'^'■".)>. I'^'O. 012, 135, 138, 139, 967 I'lirtNchcr, ()., 786. I'lisiiteri, K., 289, 402. Kalil, 919. Habl-Klickliaid. II., 100. liainoii. I). .S.. 775. K'aiiiuii y ('a,jal, 1'., 800. 811. Ramon y Cajal. S.. 3, 9, 10, 20, 21, s, 22, 23, 0. 10. 24, 25, 26. 28. 29 3(i -'J7, 70, «.'{, 77,81. 42, 43,82 44 47 84,92,94.97,128. 141,142. 166* 07' 1H4, 186.260,261.262, i;,7 266 ''>69' -'TO. 20(;, 2ii2, 382, 402, 459, 465,' 467' 468, 470. 30.-,, 474, 480, 484, 487 3'»o' •m 502. 334, 505, 511. 512,'33.s' •'■'1 4, 518. 343,34(5.522. 523, 350' -•;«), 534, 3.',4, 537, 3:,(5. 3:, 7, 3.-,s' r.40.3.-.O, 370. 371, 555. 564.577' -'582, 606, 618. 400, 410, 626 627* (I '■ ill !ii 1 1004 THE XKllVOUS SYSTEM. I-Ji 62!», 412, 4l:i, (i:Jl.(m, 417, (WT. 41«. 0-10, (541. (i42. +21, ('.44. (;-.4. (ir.ii, 6(!'j. 4;{:{, (ici, 4:u, (i(i4, 4«(k 4«»4, 4«.'», 7(18. 7(i!), 7T(». i«n, 4J»2. 772, 784, ."iO:}, 7!»r., H(l(). .')12, SO:i. NOO, HIO. KU. .-,15>. .-,27, H21, H22. 8:i2. H;i;{. 8;i7, 842, 84:«, 847, .')41, 542, 8.");i, 804, 855, 857, 858. 85 54s. 54». 8(i2, 8(i4, 8(15, 8(i(i, 88!), 571, !I2(J, 5»4, !»:5.5. (JOO, !t;!8, !l(i7, 072, !»7!», 10.i:j, «55. 1054, 5, 2.'{5. 277. .{40. .'MJ4, 42s, 45«, 572, 5SS, <{(»<». Hanvior, L., .'5, 5», 104, 183, 184, 224, 227, :{0(t, :i8;i, 254, 4i;J, 470, 855. Kiivn, E.. li)4. Kawil/, 17, 143. Roillicli. E., 440, 452, 473, 1036. Ui'ic'li. yi, 788. Reii'liiM-t. 607. Kfid, 802. Hi'il. 007, 071.688. 002. 097. 714. 717, 750, 1044, 1072, 1074. Hfinliold, 05(1. HcisiiiT. .\..421. lU'inak. K., 3, 102, 142, 197, 899, 900. Hetzius, (;.. 9, 29. 34. Hi. 3(), 73, 90. 104. 188, 202. 2(U). 15!>. 209. 1«0. 350. 2()S, 361. 211. 212. 3 74. 227. 370. 22!». 378. 2;{;{. 394. 25(t. 257. 25S. 421. 27!>. 4(i5. 499. :{n2, 526, .'{«1. 540. ;M>4. 751. 47.'{. 752. 474. 475. 47«. 754. 477. 897. Renter. 919. 5»0. Rics... II.. 34. Rclaiulo. 24. 1 16. 473, 474. «.O0, 888. Roller. ('. F. \V., .■)02, 014. 021. R(.ini)eiy 191. Rose, ('.. 381. Roseiilieiiii. S.. 144, 145, 448, 2»5. Roseiitlial, 3. Rosin, IJ., 107, 108, 127, 128, 135. Ross. .lames, 339.340, 341. Rossi, l\, 441. 444. Rossoliino, (J. .)., 001, 602, 604, 716. houx, W.. 155. 247. Roth, 413. Rolliinaiiii, i>83. iJiil.ner, M.. 249. RiUliiif^er, .'{40. 5SS. Riifrnii, .\iif,a>lo, 24.'>, 24«, 390, 247, 391, 24S, 24», 392, 2.50, 39(J, 25.'», 416, 27.*{, 274. Riif;o. 19.5. Ruiiipf, Til., 308. Russell..!. S. R., 598,0.32,655,901,902. 914, 904, 908. Ryder, J. A., 302. SalMii, Eloivnee R.. 318, :{25. 504, .505, :{.'{5, 507, 508, 509, 549. .'{«7, 568. 407, 411. ()32. (i90, 694, 721, 777, 837, 843, 5».'{, 943, 958, (ill. Sabnizes. .1.. 289. .Saeerdotti. ('.. 239, 290. Sat:lis, n., ()08. Saehs, II., .52(>, 815, 823, 1059, 1060, 1061, 1082. Sachs, Iv. von. 155, 372. Sachs, S., 826, 828. Sachs, Z., 830. .Sadovsky, S., 235. Sala. 0. ii., 259, 200, 505, 032, 849. Salzer, F., 785. Saiictc de Sanctis. .'{»2. .'{!>;{. Siinderson. .1. B.. 1003. Saiidinann. (i., 894, Sandnieyer. 983. Sano. F.', 911. 912, 5S5, 5S({. Sarlio, A.. 288. S.axter, T,. 717. Scii'.iia, 49'\ Schjifer. E, A., 2,1 29, .39. 40. 47. 5.% 307, 59-,. 903, 979, 994. 990. 997, «:{.'{, 999, •;:;+, looo, 1047. SchalT.M-. K.. 111. 149, 290, 444, 458, 4()2. 471. 592. 716. Scliaiier. A.. 167. 108. ScliielTcrdeckcf. I'., 89, 142, 7», 2.'15>, 441.44(>. 884, 894, 573, 896. SchifT, !000. Sehleidon, 2. INDEX OF AUTHORS. Schlosin^'er, ir., (584, 717. ■Sclmiaiis, F., 44(5 •Schmidt, 541. Sehmidf-Ritnpler. II.. 786. Sc'lmojjfhageii, 805. Sclmidor, A.. 716. Sell rci her, 46 S..W,.o,^,.>..,«,4«, «,,,„.„, Sehiiltze, JI., 141. Sehultze. Max, 4, 101', 103 ({'» i]o i;57, 140, 141, 143, r,04, .loo/.j-,.;' Schulze, F. H.. m-K Selnvaho, II., 911, )ra), "(Dl Schwalbc, G., 79, 104. I70, .",05, 525 748, 750, 884. Schwann, 2. 784. Sciamanna, E., 1002. Sclaviinos, (}., 2Ho, ;]82. Scolt, im, l;J4. S:d-j\vick, A., 44. Sfanicni, P.. ;jf)2. Sherrington, C. S.. 66, 86. 251 009 332, 333, IJH. ij)o_ ,,).{ .j,jy .j.j^' J38, 3,^415. 463, 554, 576; 983! Shimaniura, S., 241, l.'J.'i Shore, 921. Shiii<(nv.ski, ({70. Siegfried. 132. Sieiiierling, K., 7|)o_ 949 Sihler,C., 417, 896.' Sioli, 1048. Sniirn,,w, A., 15.34,36, 269, 386, 242 2«S, 41], 2«». '"*"• Smith. G. ]<:., 10,56. Socrates. 220. Solder. F. von. 463, 598, 601 Sottas, .J., 443. SouidianolT, S.. 290. Souijue.s, A., 443, 463. Spencer, Ilerliert, 7, 65. Spiiler, 415, 458. 1044, 1047 Spirljis, 184. «i;i"/! Stein, (Jertr.ide, 731,725,875 Stenier, ,1., 316. Stei)hen, Leslie, 221. Sliedii. 434, 930. IJtilling, M..i73.474,581,423,650. ^Iii'lnig, 45. Sliihr, A.. 1.55. Strieker. .S.. 103.668,783. Slroel)e, H., 34.5. 390. •^';:"'f- ^' «- 'ii'39, 931. 10;5,3, Strossner. 41,3. •^trihnpe]i,A.,343,244,423,428,448, Swierczowskv, 379. S.vlvius. 734. 9.38. 997. Symington, ,1., 1056. S/ymonowicz. W'., 36, .365, 368 «»'»(» -?-*I, 383, 28,S, 384, 393, 2:,1.' " 'r.-imijnrini. 346. 976. 'i'anzi, 100. Tartnferi. F., 38. 534. 540, 784, 800 ■^'•4, 809, 810. ' Tedesehi, A.. 346, 1 .',({. Testut, 598. Teuschor. !{.. 9. 405. Tlioma, 14;{. Tl.om.a.s, A.. 290, 442, 513, 553, 655, ^ ')■)., 841, !)(i6, 967,968. Tlionias, II. M.. 1071. Thorl.urn, W., 1})4," l{).-i, 339, 340, i'M». 'I'igges, 246. Timole..w, I)., 2.'{4, 382, 237. Tirelii. V., 246. Toinsii. 279. T'H'lh. II. Il.,037_4;jy ^^,^ 4.)7. 591. Trepinski. 424. 430, 433, 433, 434 43.5,436,437. 'rrincliese. S.. 272, 415. 'I'umarzew, 418. ji I ^ ) 1(»5M) THK NERVOUS SYSTEM. ii f Tilrck, Ii., 235, 227. 30(1, 331, 332, 732. 1012, l()4r). TunuT. VV. A..r)23,r)(!r).r.70,r)72,3H3, 573. »S-4, SHo, 5H(», 3514, (550, 055. 708. 717, 747, 748, 74!), 06'?, 9(!5. !»73. 1055. Tscheniiak, A., 318, 319, 320, 568, o7;\ 575, 601, 602, 603. 604, 615. 617, 618, 681, 682, 683, 684, 685, 6!)4. 701. 703, 703. 455, 704, 708, 70!), 457, 45S, 711, 712, 713. 714, 715. 741, 960. 96!». 970. 972, 973. Tschiseh, W. P. von, 674, 676, 681, 736. Uiiverricht. 983. Uskow, X., 194. Valentin, G., 233. Valentine, 3. Vanlair, 229. .'30. Vas, F.. 278. 1({7, 288. Vater, 3!)3, 396. Vejas, P., 654. 716. Veratti, 140. Vesalius. 795. Vialet, N.. 1059. 1061. Vicq (I'Azyr, 671, 768, 771, 821, 878. Vieus.sens, 594. Vignal, W., 167. Virchow, K.. 315. Vitzou, A. N., 246. Vr.lekcrs. ('., 949. Vollmer. E.. 421. Vulpian. 22!). Wagner. R.. 3, 384. Waldeycr, W.. 5. 12.29. 39. 40, 42, 43. 47. GO. 63. 154. 235. 266. 400. 463, 473. 884, 888. !)04. 913. Wallenberg. A.. 646. Waller. A.. 18, 224, 227. 228, 233, 306. 308. Walsh. .1.. 332. Walter, G., 261. Warrington, W. M., 45, 133, 240, 288. 177. 2!)9. 30!», 914. Watase, 14!). Weigert-I'al, 627, 694, 728, 777, 859. 968. Weigert. ('., 12, 25,44. 45, 64. 92, 106, 238. 339, 242, 254, 423, 432. 447, 463^ 460. 473, 474. 573. ,580, 617, 621. 676^ V25. 730. 768. 788. 854, 868, 929, 938^ !)57. 964. 986. 1023. Weinberg, K., 44<{, 45(J, 515. Weisniann, August, 155. Weissinann, 413. Welch, William II., 10. Werdnig. ().. 71(). Wcrnekinck. 653. Wernicke. ('.. 671. 814. 818, 830, 832, 1033, 1059, 1009, 1075, 1076, 1077. Wertheiiner, 983. Westphal. (".. 423. 428, 448, 473, 484, 917, 942, !)43, 944, 945, 949. Whitman. (". 0.. 44. Wiederslieim. 100. Wiener. II.. 241, 45!), 300. Wiesener. 154. Wilbrand. U.. 826. 827. Wilder. H. G., 40. 161. Wilson, E. H.. S4. 154. Wijhe. .1. W. van. 195, 125, 201, 919. Winkler, (".. 1048. Wolfstein, I). 1., 43. Wollenberg. 243. Wolter. 102. Worcester. W. L.. 311. Worotynzki. R.. .598. Wright, II. K., 288. Wrisberg, 350. Wundt, W.. 258. Yeo, (J. F.. 899. !)00. 1000, 1028. Young, H. 11.. 37. 421. Zacher, T.. 1044. 1046, 1048. Zaf)pert, J.. 451. Zuckerkandl, E., 748. SriUECT INDEX. The numbers in ordinary type refer to nn,ro. • .u subject is discusso,!: the numbers T„ hi /f '" ^" "'^'^ '" ''^^'^ ♦he figures in which the objects I" musl^ated" ''' "''^'" '" "'™^"'- «^ ^. abducens. Bechterew), sec -lateralis super Abducent nerve. Aberrant bundlf Fasciculus veii^ ficialis. Accessory olivary nucleus, see Nu- cleus olivaris accessorius. Acoustic cortical path, direct (Held) 839. '' tubercle, see Nucleus N. cochleip dorsal is. reflex paths in formatio reticularis, 55 7. Acustico-facial complex. 117. Acustico-lateral component of cere- bral nerves, 922. Acute cell disease (Nissl), 291. Adendritic neurones, 73, 74, 3(j Aeusere gram Zone, see Cappa cinerea weme Lage, see Stratum zonale col- liculi suporioris. Ae.merer Kern (Hurdach), 673. After-brain, see Myelencephalon Agnosia. 1078. Ala cinerea, see Nucleus ahc cinerea. Alteration with rarefaction around the nucleus (Iloch), 293. Alveolar zone, inner (Apiithv), 56, .W. zone, outer (Apathy), m. Amacrine cells, 82, 44, ,537. Ampharkyochrome cell, 118, 119. Ampulla membranacea superior, 3(n. membranacea lateralis. :{(n. membranacea posterior, 3<{1. Amputation, changes in nervous svs- tom after, 229. Amygdaloid nucleus, see Nucleus amygdala'. Anaxones, 82, 45. Angeiotome, 19(J. Angular gyrus, see Txyrus angularis Angulus lateralis. 7.52. Anophthalmia, congenital, 823. Anosmatie animals, 749. Ansa hypoglossi, l!S({. lenticularis, 685. Fteduncularis, 685. Anterior central gyrus, motor func- tions of, 995. cerebral vesicle, 88. commissure, axones of mitral cells in, 758. commissure, termination in gvrus hippocampus, 764. lateral nucleus of thalamus, 677 medial nucleus of thalamus, (i77 ""cleus of thalamus, dorsal and ventral, 679. olfactory lobe, 90, 749, 472. Antero-lateral ascend in'g ti"act, see Fasciculus vent ro-lateralis s'uper- ficialis ((Jowersi). Apathy's fibrils, 54. I-^leiHetitargittei\ 60, 273. \ Apathy, theory of, 273. j Apex columna. dorsalis, 387. I Aphasia, 1076. 1097 I ( H 1098 THE NERVOUS SYSTEM. Aphasia, optic, 1078. sensory amnesic, 1078. Apraxia, 1078. Aqueductus cereliri. 815-321. Arciied or arcuate fibres, see Fibra> arcuatu'. Area of Broca, see Area jmrolfactoria. parolfaetoria Hroca\ 750. Ariivodironu' cell, 117, 121, (»7. Arkyostichochrome cell, 117, 121. Arnold's bundle, 1044. Arsenic, action of, on neurones, l(JJ), 172. Ascending cerebellar tract, see Fas- ciculus spino-cercbellaris. Association centres of cerebral cor- tex, (;7.'», «7«, 1073. centres of cerebral cortex, lesions of, 1078. fibres, lobus occipitalis, (Jfi8. neurones, 0(»7. Ataxia, sensory, 1077. Atrial plexus of heart. 123. Atropiiy, indirect, of nerve fibres, 18. Auditory conduction paths, 836. conduction paths, neurones of, Hii't. 5(>l» f 'alear avis, ({J.'J. Calearine fissure, see Fissura ealca- rina. <'allosonuirfri„al fissure, see Sulcus oinguli. Calyculi gustatorii. oS.'), ;{47, 34s. Canaiis centralis. ;{()>s, !(io. Cai.pa ciuerea of superior collicuhis HO!), 810, 5IJ). t'apsula. externa, W,\S. interna, lja'niorrliaj,a» into 1014 «41. interna, motor fll)res in, i)80, J)fS7. interna, retro-lent iciilar portion of 838. interna, strucfuiv of. l()o;{ ({;j(j_ (53S, 1007, (J3«. Capsule of red nucleus, see Nucleus rubei'. Caryoclironie cells, 11,>. 117. joo^ Caudate nucleus, see Nucleus cau- datus. Cell body of perikaryon, changes in after section of axones, 333, 234. Cell liridges (Apathy). «(), 63. <'ell shrinkage. 3!»3. Cells of Martinotti. 976. Cellnlifiigal conduction, l)v axones 3(i6. by inedullated collaterals. 270. Cellulipetal eonduction by dendrites 306. I'entral gray matter of mid-brain, see Stratum griseum centrale. gyri, see Gyri centrales. Central gyri, sensory pail, from „„.- •lulla to, 704. '"'"'•"•"•■s of olfactory conduction path, 748. optic path. 821, .>27. sulcus, see Sulcus centralis. P"tiis of brain (von B.-chicrew) (''■nlmh> n„„hrnh<,hn, see Fasciculus tegmenti centralis. Jl!>hl,'>„jmn, see Stratum griseum eentrale. (.'vittn' nnti-n'cur. 674. nddiun, 674. »io!/e)i (Luys). 673. Centre, medullary, of cerebral hemi- sphere, see ('..„t rum scndovale. Centrifugal, eerebelhir path, 96,-). «I.'{. fibres in lemniscus nicdialis, de- scending. 1017, ({44. Cent rip,. i,V lib,vs conducting bodily impulses. 666. trigeminal nem-ones, central, 641. Centrum ovale of Flechsig. se'e Tri- , oOS. 7!»r». opticum, decussation of fibres in, 7N.-). opticum, (le<,'eneral ion of, TM!>, .'>()4. Cingulum. 10(>1, !). Circumccllular plexuses. 11.'). Clarke's nucleus or column, see Nu- cleus ilorsalis. Claudius, cells of, 3(>4. ('lava (did)), .')()(», ,'{7*J. Clind)iug fibres. Ho, .')2. Column of Tiirck, see Fasciculus cere- bro-spiiudis vontralis. Cocldcfir root of auditory nerve, see N. cochlea*. Ccdom, unsegmcnied. I!t7. Cold points, ^^hi. Collaterals, 21, 22, !»0. from axoncs of pyramidal tract, l();i;i. reflex, 2(5. Colliculus facialis, ti'2. inferior, .'{14. SlS. :{1», .'{({{J, 3S2, Tttio, 838, 84:{, 847. inferior, relation to auditory path. 87:5. superior, 31(J-:{'-»4, tW.). .'{St». superior, fibres from lateral lemnis- cus to, 8(58, .'».").'i-.').'>S. superior, fibres to occipital cortex from, 81!). superior, path to spinal cord from, i»6!». superior, termination of optic fibres in, so:}. superior, zones of. 808, 809. Columna cxtrendtalis inferinris, 914. extrenutalis superioris, !)I4. ),n'isea dorsalis, ,'{7I{. {;risea ventralis, .'{74, 4()7. inleruiedio-lateralis. 9i;{, ,'>8,i, 586. lateralis, 915. nu'dialis, 9i;{, 5S5, 5S(». 915. posterior, see Columna grisea dor- salis. Comnni of Schultze, ;i90, 2{)5-'i»H, 448. 451, 454-457. Commissiira. ansataof llannov('r, 807. anterior alba, see Commissura ven- tralis all)a. antisrior (cerebri), 1055, (>(>(». anterior grisea, see Commissura ventralis grisea. cerebri maxima, see Corjius callo- sum. dorsalis (spinal . superior (Meynert). 5()7, 514, 515, 713.805. ventralis alba. 387, liiH). ventralis grisea (spinal cord), 387. Commissural cells, see Neurones, het- eronu'ric. Iil)res of cerebrum, (U»5. Commissure betwecMi Bechtercw's nu- clei (ventral part of brachium conjunctiviim), 315, 311>-3t,'3. 415,(5:52,420. between inferior coUiculi, 315, 414. optic, see Chiasma opticum. Conarium, see Corpus j)ineale. Concrescence (Hehl), 50. 70, 94. Conducting anastomosis (Apathy), (iO. Coiuluction avalanche, see Avalanche conduction, path. ;{19. SUBJECT INDEX. 101 ('omlii(!tioii path, sensory, from me- dulla to I'ctilnil '^\v\, 704. path, soiiia'stliL'tii', resume of, TiiO, 4«!>-471. Coiidiu'tor sonorus, H40. Coll fusion zone, !)!)."), (JiW. , Connecting plexus of heart, 123. Contact tlicory of transmission of im- pulses, 2ti2, 20;5. Convergenzcentrum, t)51. Cornu aninionis, sec Ilippocampiis. antcrius, sec Ventriculus lateralis. inferius, see Ventriculus lateralis, postcrius, sec ^'entriculus lateralis. Corpora albicantia (white bodies), see Corpus mammillare, gcniculata, seeCor|)Usgeniculatuin. (puidrigcmina, S5>, 372, oliO. quadrigenuna, relation of lemnis- cus lateralis to, 7)7i{\. quadi'igcmina, signilicance of, in animal series, 804. (luadrigemina, terniination of optic fibres in, 8013. Corpus eallosum, 1053. callosum, degenerations of, 1055. ciliare, see Nucleus dentatus. dentatum, see Nucleus dentiitus. geniculatiini laterale, 536, 800, 813, :)11,82:5, 831. geniculatum laterale, degeneration of cells in. HIT. .VJO. geni(;ulatum laterale, nuclei of, 67!l, Tl)(), ilO. genicidatum laterale, termination of optic fibres in, 7i)8. 800, olO. :»12. geniculatum medialc. .'JS(), 843, 847. geniculatum mediale, degeneration in, 875, .").'){). geniculatum mediale, fibres to in- ternal capsule from, 875, 5(»0. geniculatum mediale. nuclei of,875. geniculatum mediale. ternunation of optic fibres in, 804. liuysi, see Nucleus hypothalami- cus. mHmmillare, JK). 3H«. Corpus mammillare, connection of hippocampus with, 7. mamtniliare. nuclei of, 708. parabigeminum, 56i), 3H(J. pineale, »0, K\\. restiforme, :j(M>-:n2, 31S-321, 377, 3S:>, 504, 575. SlU, 412, 413, 417. 41 ». 580. 587. restiforme, degeneration following section of, (J 14, (Jl.'i, Wu. striatum, H{). subthalamieum, see Nucleus hyjio- thalamicus. trapezoideum, 313, 324. 3(»7-3r>», 551, 553, 402,41.j, 41 7, 012, 537, .->3S, 843. trapezoideum. transverse fibres of, 850. trapezoideum, terminals of axones on cells in, .■)4.'>, 540, 547. 857. Cortex of human brain, (}(i3. Corti's membrane, 3(J2. Cortical l(>minscus. 007, 690. Cortico-muscular conduction path, 1037, (>r)7, (J.'»8. Crista aiiipullaris, 490. Crossed ]iyramidal tract, see Fascic- ulus cerebro-spinalis lateralis. Cms cerebri, see F'edunculus cerebri. Cutieate funiculus, see Fa^riculus cuneatus. tubercle, see Tubereulum cunea- tum. Cuneus, r»24, ii34, PI. I, 3. Cylinder furrow, KMK ( 'i/liiiilrodendrifen, 90. Cytochrome cells, 115, 121. Cytodendriten, 370. Darkschewitsch, nucleus of. 721, 724, 4<;2. 4(J3. Deckfilalte, KM). Deafness, mitxl, 1078. word, 1070. Decussatio brachii conjunctivi, 310, 322-324, 415, 42<>. 42». lemniscorum, 30H. 503. 447. nervorum oculomotorium, 942. r I 1102 THK NKRVOUS SYSTEM. Deeussatio ncrvoriiin trochk'iu-iuin, ;II4, 940, (M)2. |.yniiiii(luin, Dbl, !)!)0. UDl, «24. siibl Imliunioa anterior, see ( 'oininis- siini liypotlialiunica aiilcrior. tfj,'iiR'iili (lorsaiis, 772, !)«!), i'.io, 4»2, «17, «1S. tojjinenti ventralis, 4*i{>, 4:J.'>, (»1J>, !»71. Decussation in optic cliiasin, com- plete (von fJuddcn). T!»0. in optic cliiusni, tiicorics oi', 78'1. of fillet, see Uecussatio leninisco- nnn. of pyramids, see Decussatio py- ramidmii. Dcctissationcs tcginciilDriim, ']1(>. :U7, 324. 40.>, iUi, 4»;{. 4».i, 772, 813. !)69. Deep cells of niitdi'i X. trigcmiiii, 043. optic path, H31. Degeneration after amputation. 338. after lesion of cerebellum. i(64-!H)7. after lesion of gyrus centralis pos- terior, 703, 450. after removal of eye, 787, .")()4. after section of cor|)Us restiforme, 967, (;i4, (Jl.'). of cell-body on removal of affer- ent impulses, 2'2U, 177. of nerve cells after section of axone, 333, 334. retrograde. 339. secondary or Wallerian, 18,46.234, 337, 143. 144. Deiters, cells of, 3(»4. Deiters' nucleus, see Nucleus N. vestibuli lateralis (Deiters). nucleus, tract to spiiuil cord, 311, 312.321.322, 3«S. Dendraxone, 14. 70. 41, .">.">. Dendraxones between U{)per motor neurones, 1036. Dendrites. 4, 15. 1<». 37, 70, 111, 189. effect of injury to, 339. origin of, 169. theory as to nature of, 258. Dermatomere, 196. Descending centrifugal bundle of lemniscus niedialis, 1017, (»43, halon, 1")9. S{>. motor neurones in, 969. Diffuse cells of retina. 7H3. Dijilomeric mus(des, 301. Direct cerebellar tract, see Fasciculus spino-cercbellaris dorso-lateraiis. pyramidal tract, see l''asciculus cerebro-spinalis ventrali.s. Dirccte (iciinfische RindenbaJm, (Held), 868. Rindcnttchhife, 607. Dorsal commissure, see Coinmissura dorsal is. decussation of tegmentum, see De- cussatio tegmenti dorsalis. funiculus, see Funiculus dorsalis. horn, see Cornu dorsale. nucdeus of lateral geniculate body, 079. iniclcus of reticular zone, 677, 079. root, see Uadix dorsalis. white matter of nucleus hypotha- laniicus, 684. DiTi7,((ntpulni/in (llelweg). 958. Ductus cochlearis, 301, 3(>2. cndolymphat icus, 3(>1. reuniens, 3(>1. semicircuhiris lateralis, 301. utriculosaccularis, 3(>1. Ectoblast, 165. Rhrlich's vital staining, 31. Electrical stimulation of cerebral cortex, 993. stimulation of neurones, indirect, 370. Elementary fibrils of Apathy, 54. m^ SUB.IH(T IN'DKX. ii(i;5 HIementargitter, seo Apiitliy's AVe- menl>ir(jU,ter. Kinliolus, sec NucliMis cmboliforiiiis. KiiiiiuMiLia iiilLTiifdiinculiiris of istli- III us, iJO. Kiiiir yochroino wUs, 118, 110, «8. I'iii<'('|ili)il(>ll, l(i3. KiHl-hriiin, sco Toloncoplmldii. Knd-ldilbs of Krause, 2.') I. ;!!»:.'. :!!)«. Kiiliirgc'inciits of cord, see liiluines- eontiuB. Eiiloroiiiere, 106. Kiiliy zone, 42;{, 434, 427. Kpislnituin, 500, 781. K|)itlial(iiinis, 80. iv|iiivalent picture of nerve cell, 1!}3. h'isa/z-Theorie of tabes (Kdiiiger), 254. External capsule, seo Capsiila ex- terna. Extirpation of facial area, (J.'il. 1030. of iiallux centre, *JJ). centralis tegmculi, 401, 403, 404, 728, 074. cerebellaris lateralis descendens, 66:5. cerebello-spinalis, see Fasciculus .spino-cerelu'liaris dorso-laleralis. cerebro-spinalis anterior (pyrami- dalis anterior), see Fasciculus cerebro-spinalis vcul ralis. cerebro-spinalis lateralis ([lyrami- , ;{00, GOO, 084, 002, 030, «31, 1045. cerebro-spinalis ventralis, 30(), soo. o;i;}. cerelu'o-spinalis ventralis of mon- key, 1027, 040. cruciatus, 785, 507. cuiiealiis (Burdachi), Si5, 280,203, 205. 301. 302. 304.308,318- 322, 372, 373.370,405, 44;J- 457, 401, 402, 4(58. dorsalis proprius, 550. dorso-lateralis (Lissaucri), 25, 280, 281, 3SM), 42:i-4.'i5. 408. gracilis (Golli), 8. 2({. 304, 308, 318-322, 372, 373, 370, 405, 40(>. gracilis, degenerations of, 280, 2{>2, 203, 442-447. gracilis, origin of. 4;i0-442 ; termi- nation of, 301, 302, 4(il. 402. liitcralis limitans, 008, 0()!). 3JM>. lateralis proprius (Flechsig), 300, 415,550, 011-614, 740. lateralis ventralis, 740. longitiidinalis inferior. 1065. «»72. longitudinalis medialis, 300-317, 310-324, 380, 401. 404-400. 414-417, 420. 6i:}-61!). 627, 637, 422, 668, 675, 718, 721. longitudinalis medialis, connection with cord, 450. longitudinalis medialis, motor neu- rones for, 959. rv If (. f 1104 TIFK NKUVol'S SVSTKM. Fascit'iiliis lotiKitiKlinalis superior, 881, ion;{, «71. iiKiciilaris (•riiciutus, r>()7, 7!)"). muculiiris iioiicniciutiis, dorsiilis et veiitnilis, 'i07, VXt. niftrtfinalis anterior, 957. ii()iu'ni(.'iutiis, 7K.-., oori. .-)()«;. :,07. (iciipitiilis triiiisvcrKiis c'unei, 1000. iH'i'ipitiilis tnuisversiis f,'vri liiigii- ali.s. 10(U. occipitalis vorlicalis. 10r)9. oceipito-fruiitalis, lOtJH. paliio-froritalis, 1()4(». pallio-frontalis, (legciicnitioii of, mi. retrollexup (Meynerti), 317, 323, 3'Jl, 3H«, 775, 777, 4«S. retrollexus (Meyiierti), relation to red nucleus, 45)1), 778. .spino-cerel)ellaris dorso-lateralis, 3()S, 320. 575, 3»(). 585-589, 3!):», 3{)(;, 975. spino-ccrel)ellaris veiitru-lateralis rcstil'oiiiialis, (iOIi. thalanio-iuainuiiilaris (Vicq d'Azy- ri), 3S({, 708, 771. unciiiatus, 1000. veutralis jM-oprius, 559, 30«, 30.S, 401, 40«. (ilO-014. vciitrolateralis .superficialis (Gow- orsi). 559. tUH. 302 30(J, 3J)0, 590-598, 3{)«, 3S>7, 3»!S, 001-604. Fatigue, influence of, on neurones, 270, 277. 1«4, 1«J({. Fi'/d II, 655, 43(J, 071. Fe/d 1I„072. 438. Fehl Ih, 072. 438. Feld Ha. fibres from fasciculus longi- tudinalis niedialis to, 008. Feltwork (Neuropiluin), 17. Fibric arcuata' externiB, 308, 370, 505, 575. arcuatns interna>, ilOH, 30{>, 320- 324, 56:5, 565, 508. arcuatiB interna- from nuclei tcr- minales X. trigeinini, 422. arcuatjr interna', relation to nucleus alai cincrea', 024. Filira' arcuttla> interna', relation to nucleus funiculi cuneati, 420. arcuata- interna' (vestii)ular), 31}), 027, 800. .'>:»«. poiitis, 312. Filirrx cor'Iro-rithi-iqHes di'irctcti, 732. Fila olfacl.-ria. 478, 500. Fillet, see licmniscus. Ki.ssura calcarina, (538. eerct)ri lateralis, Plate I, 8. cliorioidca, 00. parieto-occipilalis, I'late 1, 3. prima, 749. rliinica, 749. Sylvii, (>33. Fif<.siirenKtntn(/, 960. Flechsig's embryologica! method, 25. sensory systems, 7;i5, 4(>(>-408. Flocculus, 372, 411. peduncle of, sec Pcdunculus floc- culi. Fontnini'iirtige ll(tuheiikre\(zunii of Jleynert, see Deeussationes teg- inentorum. Food-stulTsof neurones, 218. F(jrebrain, see I'rosenccplialon. Forel's ventmlc /Iaidie)ikn'iiziini/,7~2, 402. Formatio aremita, 100. reticulari.s, 176, 015 728, 401. 412, 404, 4(»r», 500, Oil. 618, 629, 690. reticularis alba, 727, 959. reticularis grisea, 721, 960, 460. reticularis. optic and acoustic fiiires in, 557. l<'ornix, 1067. Fossa cerebri lateralis (Sylvii), Plate 1,3. Fovea, anterior or superior, 372. Funiculus anterior, see Funiculus ventralis. dorsalis, 22. 56:5, 300. dorsalis, fibres from nuclei of, 709, 711,71:5. dorsalis, function of, 709. dorsalis, injury to, 708. dorsalis. myelinization of, 281-288, 424-4:57. SIIIUKCT INDKX. lion l''iiiiiciiliis(lnisiilis, orifjiii of, 4r)7-4(ll. liilcialis. H, :ttO, :ni. 40.T!)1.'). liilcnilis, lilnf hv■^*t^■lll I'miii imi'lciis ruber to, 4'J2. |icslcri(ir. svv Fiiniciiilus ilorsiilis. veiilrulis, tlTil. ventro-liilernli.'s, llbri's from Di'ilcrs' nucltiiis to, !l()0. Fusum'/ileiJ'e (l""lcclisig), ()H4. Ounglia, spimory. (m«11s of, OH, :{1, 17!», 108. trunci .symiuitliici. 1!H), is.'i. nutif^lion cells uf A|mlliy. "»'-i. •'")4. coiiiini.ssunilL', sue Nucleus coiiiiiiis- su rails. f^ciiieuli, ■)!.'!. luilx'uulu', sec Nucleus Imbciiulii*. juj,'ulare, 478. nodosum, 478. petrosum, 478. scmilunare ((iasscii), 514. spinalc, 185, 1m:{.:{1(),;j11.'2O7,20», 21U. spiralc, 112, 117, 545. sui>erius. 478. vcstiliulan; (.Scarpa"), 499. Oanglionic ridge, KM). Uasserian ganglion, see (langlion .semilunare. (lastrocnemius muscle, nerve endings in. H!I4. (Icmmulcs, 7C, 37, fi*) ; loss of, 240. Oeniculato body, external, see Corpus geniculatuin laternle. body, internal, see Corpus genicu- latum mediale. Genital corpuscles, 2.>«, 2(;i. ;«)fi. tieiui cajisuhc interna', 1005. N. facialis, 3«8, 411. !i;iO. Gerlach's dilfuse network. 7. 60. Giant cells of substantia gelatinosa, (m. 421. l)yniniidal cells, 078, «21. Oiilcrschicht^an, 438. Gittei-Kch icht/cenie, 679. Cilandula pinealis, see Corpus pinealo. pituitaria, see Hypophysis. Globus pallidus, Plate I, 3. Glomerulus olfactorius, ."»(), 5:M, 757. GolKi'scell of Type I, 11, 12. cell of Type 11, 12, 13. cells, Type 11, inlcrsegnu'ntal. 9.52. cells. Typo II, between upjier and lower motor neurones, lOltd. ditfuse network, 15. Golgi-Ma/zoni corpuscles, 2.'».'», 31M{. (iolgi's melliod, 9. Goll's fasciculus, see Fasciculus gra- cilis. Gowers' tract, see I"'asciculus ventro- lateralis superficiaiis. Gracilc nucleus, see Nucleus funiculi gracilis. Grande lobe limt)i(pie, see Gyrus for- nicatus. (irandry's corpuscles, 220-224. Granule layerof Fleclisig's tvtn/torale liiec/i.yihdre, 759. Gratiolet's radiation, see Hadiatio oc- cipito-thalamica((iralioleti). Gray commissure of cord, see Com- missura grisea medulla' spinalis, matter, central, see Substantia gri- sea centralis, suiistance, see Substanlia grisea. (/i'u,ss/iir)i, see Cerei>niin. Ground-bundle, antero-latt'ral, see Fasciculus ventralis |iroprius. Gryochrome cells, 117, 121. Gudden, commis.sure of, see Commis- sura inferior Guddeni. law of, 18, 44. Gustatory conduction path, central neurones of, 747. neurones, see Neurones, gustatory. Gyri cerebri. Plates I and 11, (»3S. occipitales laterales, Plate II. 1, . 1(1(11. foi'iiiciiiiis. i'iiilf I. ,'J. fi-ipiiliiiis inrcrior, I'll Ic II. |. froiitiilis iiicilius, I'liilc II. I. frdnliilis superior, I'liiii'lioii of. UUI). Iiippiiciiiiipi. 7(;.i, liriituiiiis. IMiiti^ I. 4. oll'iictoriiis lutemlis, 751. 473, 474. 47.V olt'iicloriiis lucdiulis. 7."»1, 47S. Sfriiiliimiris I'liiiiciiccpiuili. 752. siiiiciillnsiis, .'lOI, .'•(►•i, (».'{N. siipriiiniii'u:iiiulis, Plate II. 1. ti'iii|Hiriilis iiu'iliiis. I'liilo II, 1. tfiiiporiiiis superior. 'Mi, H78. uuciuatus, see Uncus. Hair iM'lJs of oi'fj:aii of Corli. lUH. Hallux ceMtre,(le<;i;nerat ion following extirpation of, -4».'>0. in-,>4. centre, pyramidal lilires frnm, KKK). eentre, decussaiion of. lO'Jd. (»4H. //(iii/i('iiln"ui(/i'l (/cs /jiiiKi>ii/iernea,674. (li'f< ntf/wn Kcnu-x, (i74. (Ic-s TlialtimuK. (!74. of von (luddcn. see Fasciculus pe- dunculo-nuunniillaris. noiihrnfdsnMn (l-'orel). 435, 670. //itH/x'iik'niiziiHt/, see Deeussutioncs tegnientoruni. Hitiihi'iiHtrahlunii, 607. 7!iO. //iiii///,sr/;li'ifi',iiL'e Lemniscus niedia- lis. dcr Sc/ileifenscfiiclif, ()«7. //iiiip/f/iei/ dcr ScltlcifenHchicht, (187. Head area of cerebral cortex. i)!)8. cavities, i)18, Dili, fold. SS. plate. SM. Heart, plexuses of, 123. Ilecateroinoric neurones, see Neu- rone, liecateronieric. Hold's method, 12!». Hemianopsia, Hi.'). H26. llemispliariuni cerebri, lateral sur- face, 675. Ilendsphnrium corebri, medial sur. face, (176. II( iiiisplierie bundle of von liudden, 807. .'»l, 430. llypof,dossal nerve, nucleus of. !)24, M,t. nucleus of lioller, small-celled, !»26. Hypothalamus. JMK liiyers of. (171. limits of. 671. paths to, 6(!H. region of, (UK!. Iiiiixones, HI. Individuality of neurones, 38. Infections, changes in neurones in, 28! ». Inferior collicidus, nucleus of. see Nucleus colliculi inferioris. colliculus. relation to auditory piilli, 872. fillet, see Lemniscus lateralis. Infraconscious impulses, 250. Tnnerer Keni (Hurdaeli). 67!1. fnsehvhwfUi' (Schwalbo). 750. Insula, Plate 1, 3. snUKCT INDKX. ll(>7 liilcr-liraiii, hw Diniii'i'pliiilon. lull rccllularliridp's.sfi' Cell liridKi's, Iiilfriiisiilar j'clls. 421. Iiitcriiu'diary liiniina iiu'dulliiris, 4:in. iiinliir iiciiriiiics, ))"»!•. Iiilfi-iial tapsiilc, sci> Capsuia iiitcnia, IntcriuMiroiiul rolatioiis in ciMvltral cortex. <{.'>.'>, <{.'»({. siihslaiicfs, !H». liilnrolivary layer, sfc Stratum iiitcr- ulivari' li'Minisi'i. liitcrsf^jiiu'iit, liMi. Iiilcrstitiul ci'lls nf sensory nufU'us ot' trip'iiiiniis. (M',\ 4*il. Iiitoxicalioiis, clmngcs in ncunmi's in, aH2. Tiilc'r|iari('lal sulcus, see SuUmis inter- puriclalis. Intunicsccntia cervicalis, motor neu- rones of. MHr.. i)(t.-|. .'iTH^.'iS'i. luinlialis, neurones of. yST. Irritaliilily of neurones, 34H. Island of |{cil, see Insula. hluirs i>lf(i/iru'i. 7(H, 4S7. 4HS. Istliiuiisof brain, see Isthmus rlioui- iienre|ilitili. riioinlience|iliali. SU. It el' a tertioad (juartuin venlricnlum. see Ai|Ueduetus ccreliri. Kaiser's nucleus cxtremitatis superi- oris, i)14. h'fiiiizi'llrii, 107. Kurpi'rfi'ihlspltiiro, (l(}7. Krause's (>ud-ljull>s, see Mudhultis of Krause. Kreuzende 1 1 i iitc r.il va nfilifni-d rona- /lininitdi'iiKi/xtcDi ('rseiiernuik). 714. Ilintevstrdtxikcrn - (/rofitihinin'iKl- Tlxditni UMi/xIciii ('rseliernnik), 714. Tialiyrintlius nienilminaeeus, S(>I. Liimiiui basilaris(('orli"s uryan), ;{(>i, 8((4. terminalis, 1>0. La(iueus, sei! Lemniscus. liarKc-celled inieleus of tluilamim (Nis>l). (177. Lateral eolunin, sec I'lmiculus la'er- alis. lillel, see liemni«eus l.ilcralis. ;rcnieidate liiidy, -ec Corpus ftonicu- latiiui iatel'ale. horns, j;roupin>,' of cells in, HHH, .'»((M. line. -.2110. nucleus, see Nucleus lateralis, inu'leus of corpus nuimuiillare, 7(IH. nucleus of reticular /one, 077. nucleus of thalamus, anterior and posterior, OHIl. pyramidal tract, see Faseieulus ccretiro-spiiudis lateralis. Liiti'iidrx (dmlcii/iudiM Kleinliirn- hiiiidel, mil Lauteruuinn's sej,'uu'ntation, 4. liCj; area of cortex, !M»H. Leitiiiij/slKi/ni, iMl>. Lemniscus or hKpu'us. OSO. lateralis, :n4, .'{l.V :ns-:W2. '.W.K :is«, r,r,:\, 404. 4o:», 414, 4ir», ('•87. lateralis, divisions of. HOI. lateral's, libra' anuata' interna* from, •<('(), 'ut'.l. lateralis, finer struclure of, HOO. lateralis, lesions of. 801, 550. lateralis, nuclei of. 804. lateralis, origin of axoues uf, 803, 551. lateralis, relation to nucleus collic!- uli inlVrioris, 8(58. lateralis, termination of axones of, 800. 554. medialis, :jl.'{-S17, liHH, 504, 570, 401, 404. 414, 415, 087. 089, 44s. 440. medial accessory, 088, 44(». medialis (accessory bundles of von Beehterew), 404. medialis, descendinj,' centrifu^'al bundle in. 1017. «4:{, 044. medialis, dii'eet tilires to cerebral cortex from, Oi)i). •\| ^ lios 'I'lIK NKIJVorS SYSTIOI. is, oriiiiii of lilii'i I'iniiisciis inciljiil <>r. »!M. iiu'diiilis. Ii'i'iiiiiiiiliiiii (.r 111. res dl', <;!M. i.v>, i.-,i. s I'oiKM'i'iiiiiir cniirsi' mcdiiilis, \ ii'w <>(, l.'>|. (1(1(1, (i!i;. suiicrior. .'120, .'It! I, .MO. liudiMcnlum spirnli" cnclilci', ',Ui'2. I.iiiicii insula'. T'll. LiiisnihrniKr/i/iiH/i' ( I'Mcclisij;), (185. 1 I.i ssiuicc's ('oiiiiiui (I)' tnii'l. !•' Miiiilii'. si-o I'liliiiiiii. Mnivhi's iii.-iliod, I"). :>|'j, 'J4:t. Miirt;iiiiil ImiiiiIIi- of liissiiiiiM', SCO l''iis('i('iiliis iliiisu-liilciiiliN Lis simcri ciciiliis (Idi'sii-lalcriilis l.issiiiit'i'i. liobiilus piiraciMilniiis, ruiicli if. imniccnti'jilis, lesions nl', Tdl. I't't. Ij(>l)ns (ifi'ipiialis. 101?. olfacloriii.s. m, 74!», 47l!. Ijociili/alion, inoloi', in spinal roiil, H!»!). (if rmirtioii in ccrcln'Ml cortcN. W'y. KKfJ. of I'miciiDn in spinal cord. !Mi:t !l()."i. !tO!t, :»S.'{. Locus caTiiicus, .'{7-. lion^'il uiiinai liuncllc. poslci'ior nr dorsal, sec l'"iiscicidus lonuiludi- nalis incdialis. liowor lace ;nva. !I!IS. fticiid nerve, !•;!(». motor noui'oncs. sec Neurones, lowci' nioloi'. l-unibjir cnlarccnienl of cord, sec In- tuinescenlia hiniii.ills I uys' liody, see Nucleus livpollia- lainicus (corpus laivsiiv I/Vi'ii. see ( iiniinissura hippocampi. Maci'osinatie aniinals, 71!). iVIacula acus(ica .sjicciili, .'Ct.'t. '.U'*\, M .)(i(». aciil:i aci islii'u iilriciili, ',U>\. .Mi liilca. M'J,'). .M-JC. lulca. lilires in opt ic nerve from. TDo. Is of. 17s. :{()1, ilon-iiilril. ellc( Mainnials, nerve eiidiiij^s in innsidi lihres of. S!ll. iVItinn's mi'tliod, 1^!), cells of sensory nucleus of t ri- i^emiiiiis. (!lv', 4t!l, furrow. 100. veil, 1(1(>. Mast ical ion, development of muscles (if, ill!), :>]>(». Medial accessory lemniscus. (IKH, 4 4U, column of motor coils. !'1.">. ;,'cniculate l)ody. see Corpus e;(>- niculaliim mcdialc. niicleii.sof corpus maininillarc, 7(18. nucleus of thalamus. (i7!», 442. ventral nuideiis of thalamus (von Momdiow), OKI. Mi'tliiili' iirri;s.si)riKc/ii' liihiih'l drr Sr/i/cifi' (von Mecliterew), sco Medial accessory lemniscus. Medulla oi.loiifrata, :U)S :{li. :{|H :{'-'4. ohlonpita. lamellalion of, 177. oliloiiLjiila, pyruini Mi'issiicr's tactilo corpuscles, :!.'{?>, •JIO, 2H. JI.V Mercury, elVeds of, 2H7. Mescllcepliitluti, ITi!), Sl>, Mii :|24. Iiiiri/.diiliil sect inn lln'oiii^h, 427. lowiT motiH' neiii'diies of, Itir). motor luMirones in, !l(t!l. Mesial liilet, see Leinniscns niediiil Metaliolisni of neiii'ones, 'JI7. Melanieres, 1115. IS. MelaliialM niif S». Mela/DMiil nei've ti-iiiilis, '..*()!», l.'{,'», Melencc|.|ialon, I.V.), Si», ,'(12 .'tl<>. pyramidal fibres in. St>, 1)H|, •)•)(). Meyiierl, laim'ie of, .>. Midliraili, see MeselK'Cjilialiili. Middle cereiiellar | iiraeliiiim imnlis. I'dunele. see I'liial HS. decussation of tcf^fineiil nm. 77!i. horn of lateral veiilri(de, see \'en- Iriciilns lateralis, cormi inl'eriiis. leinniscns, see liemiiisciis medialis. or soft commissure, soo Miissa inter- media. Miftr/zc/lrnsniifcit, KH8. Millhrv wei.sxe lj(t(ji\ see Strntum album medium. Mitral cells, r.:{',\ 7r)7, 4HI. Moiio^tratilieil cells liiia, :»(>.'{. 7h;;. Motor area of cortex, !»7(J, iH»0. axoiie, endinj^ in muscle il.r. mv :,;:{. meilial and lali'i'al column it!.'). cercoral nerves, c( Mum of, 10-^2. mtrol hy pal- corlex, def.,'eneratioii follo\vin(.f (!X- tirpalion of areas in, <)4(>-(iri4. Motor ('ortex, extirpation of areas of, Kt'i','. «4r». libres from llie cortex, termination of, !»H|. function in cerehral cortex, locali- zation of, Idt."!, iV.Vl <{.'{.-,. 1()()2. localization in spinal cord, K!)j), .'»,SU. nerve spindle, .'»:{, {\{). neurones, lower, HK!, r»77. neurones of cervical cnlar;;emenl, neurones of I lie <'ord, commissural ;,n'oup of. HH."), .■'»07. neurones, ^'ronpin;; of, .SH}. neurones of rliomhenceplialon, !>I5. neurones of tlioraci<'. lumliai, ami sacral cords, HH~. neurones, relation of upper and lower (von Monakovv), l(i;i(l. neurones, np|ier and iiiteriiie(liale, nuclei of luniliarenlart,'emenl,.')S(». tclodciidrion of the froj;, r»7'». leloileiidrion nf lacerla, r>74. telodeiidrioii of the ralihil, >'f70. telodendrion. relation to iieiirl- leinimi, Nilfi. Movemelils, hiliiterally (iiuervate(| muscles, l()4(». Miiller's fibres, «.',({, .Vl?. Mnlli|iolar ;,'anj,'lioii cell, 4, li!>, '\i. Muscles of (he eye, ililiervat ioli of, Mnscle-se^nnelll, see .My(]t()ine. Myeleiicephalon, I'lit, SJ>, .'{72. .Myelin sheath. 41. Md. Myelinizalioii of brachiiim cuiijuiic- livuiii, (jr)7 (i.V.t, 4:{l. Myocommata, 1!(H. Myosepliim. HtH. Myotome, li)."», l'_»«, liM), 201). .Myotomes, profit ic; and post otic, 010, relat ion of muscrles to coiihalic, !ll!(. X. al)ducens,i»;i2,.'n:{,.r-'0-:{>24, ;{40. 41.-,. I. 'I I li f i il 1110 TIIK NERVOUS SYSTEM. X. iilidiRMMis acL-essorius, 1Siili. imriculiiris iiiagiiiis, 1S(». axillaris, 1,S«. 1S«. (u( hleii'. :{07. 311, 312, 3«1. 3(5S- 370, r,4«, 413, 41«. cutiuiL'us aiitiln-ac'liii lateralis, ls!>. c'litaiiousaiitihracliii mi'ilialis. ISJK C'litaneus hrat'liii (iorsali.s, ISIK ciitaiiciis bracliii iiu'dialis, ISJK cutancus colli, l,S(i. cutaiieiis feiiioris lateralis. 100. cutancus feiuoris posterior, 1.S7. \*.)U. dorsalis seajmlas 1S(». facialis, 307. 312. 310-324. 340. 3(n,3(JS. 411. 417, !)3(). fciuoralis, 1S7. glossopliaryngeiis, 307, 300-3 il, 320. 32 i, 320, 320, 340.377. 477. glossopharyiigciis. lower motor lU'iiroiu's of. !>2!*. gliita'us inferior. lS7. gluta'iis superior, 1.S7. liypoj,'!<.ssus. 102. ISO. 300. 321- 324, 340,370,377. iiypoglossus, in the embryo. 026. ilioliypogastricus, 1S7. ISO. ili((inguinalis. 1S7, 100. interinedius, .514. luiulioinguiiialis. 1S7, 100. meilianiis, ISO, lsj». niusculoculaneus. ISO. ohturatoriiis, ls7. 100. ticuloinolorius. 317. 323. 324. 340, 114 1, 1)4!). opticus, T;f:{, TX2, T!)">. 507. optii'us, coarse and (in(> fibres of, 785. perona'iis comnuinis. Is7. jierona'us supcrliciaiis, 100. [ilireniciis, 1S(». platitaris lateralis, 100. plaiilaris medialis, 100. X. abducens pudendus, 1S7. radialis, ISO, sajilienus, 100. spermaticus extcrnus, 187, 190, subclaviiis, 1S(». suprascapularis, ISO. Miralis. 100. tlioracol)racliialis, 1(^0. tibialis. 414. trigeminus, 522, 307, 313-310, 32 1 -324, 340. 3S0,514, .')23, 5:51, 414. 915:5. trigeminus, sensory paths of, 664. Iroclilearis, 31 .'.-320, 340, 3S0, 001, 9158. ulnaris, ISO, ISO. vagus. 102. 307. 300-311, 320, 321. 32(5. 320, 330, 340. 477. vagus, filjrcs from the terminal nu- clei of. 728. 4.'>. J>(>. segment, 11)5. Ncin'ilemma, 41, 8fi. Neuroblasts, 10. 44. 10!). wandering of. 1T2. Neurofibrils of Ajxithy. .'iS. .'»4, 14'). Neuroglia, proliferation in secondary degeneration of white fibres, 228. Nciiromere. 195. Neurone. ;5!», 41. am|)harkyoehrome, 118. 110. apykiiumoriilious. 12;>, (»S. VtU, 71. archiplasniic radiation. 148. arkyoclirome, 67, 117. 131. atti'uction splicrc, 148, S4. auditory, lirst order, 880. 8;]9. auditory, second order, 8Ii!). auditory, third order, 8;i!). axone hillock. 111, «4. S2. axone. structure of. 143, 145. axospongiur.i. 144. Si, S2. bulbo-hypothalamit', ()!(4. bulbo-mesi'ucephalic, 0!I4. bulbo-|)ontal. ()!)4. caryochniinc^. 115. 117. 133. ceiitrosomc. 148-150. S4. changes pniduced by ai'senic in. 1({{>, 172. changes produced by fatigue in, 370,377. 1(54, HU5. changes produced by injury to dendrites of, 3:!i(. changes |)roduced Ity ligature of abdonunal aoi'ta in, 1 7;{. Neurone, changes produced by mer- cury in. 387. changes produced by j)iiosphorus in, 388, 1 70. changes produced by |ioisons in, 383-388, 3!»5. changes produced by section of ax- one in (Nissl), 3:!;}. 284. changes produced by section of ax- one and of dorsal root in. 177. changes produced l)y strychnine in, 385. changes i)roduced by veratrin in, 38:5,171. cln'omophile, 115, 123, 73. clii'omphilic corpuscles, 110. chroiuophobic. 133. conception of. 40. cytochronu". 115, 131. cytoplasm, 147, cytoreticulum, 143. cytospongium, 147. S2. dendrites of. see under Dendrites. elementary spherules (Arndt). 104. cnarchyoclirome, 118, 110, (»S. endoplasm, 155. exophisin. 155, librillar theory of Schuitze. 102. librilsof. 113, 130. 130, (J2. ground substance of (unstaimible substance of Nissl), nature of, 135-153. ground substance, fibrils of, 108, 130, 140. ground substance, honeycomb structure, 138, 141, 147. 156. ground substance, network, 130, 140. 7S. gustatory. 535. hccateromei'ic. 171, lieteromeric. 171, KM. hyaloplasm, 147. hypothahunic. 004. investment of, 150-153, internal morphology of. 101, 157. mesencephalic, (i04. para|iyknomor])hous, 133, (»7. {■ i ! i I l Kl 1112 TIIK NKIIVOITS SYSTEM. Npui'oiie, poriphonil auditory, .'544. jMjriplionil wiitrifugiil, mil. pcriplicral (ilfaelorv, ^t2[K pigmeutiiry deposits, 107. pyi?sed gracilar nueleo- cerebellar, 565. system, uncrossed gnieilar nucleo- cerelifllar, 5(»5. tautomerie, 171. tautomeric, classification of. CM. tlircsliold {Winirotinc/iwel/c). 25:i. unciainable substance of Nissl, see under Neurone, ground sub- stance. visual, 5^3. Neurones, bodily periplieral centrip- etal, ;{5()-:{60. 204, 20(5, 207. 20s. 20». 210. bodily periplieral (sentripetal. clas- sification of. :!21-;i22. bodily peripheral centripetal, pe- ripheral endings. :i61-420. 211. 27». bodily i.eriphci'al c(>nlripctal. pe- ripheral endings. c(irnea. 214. 2I«. 217. 202. 400. bodily peripheral centripetal, pe- ri|ilieral cndii s, conjunctiva, 21s, 24J{, 2.i2. bodily peripheral centripetal, pe- ri|)heral endings, bill of duck, 222 224. bodily peripheral centripetal, pe- ripheral endings, bladdei-. 212. bodily |)erii)heral centripetal, pe- ripheral endings, ciliary body. 270.271. bodily periphend centripetal, epi- didymis. 2:{4. bodily peripheral centripetal, gen- ital tract, 250-201. Neurones, bodily peripheral centri- petal, hair. 225-22H. bodily peripheral centripetal, kid- ney. 27«. bodily peripheral centripetal, liver, 2;{6. bodily peripheral centripetal, mamnuiry glands. 2S0. bodily peri|iheral centripetal, mes- entery, 254. bodily peripheral centripetal, mus- cle. 203, 20S, 272. 27S, 412, 421. 803, 573, 570. bodily peripheral centripetal, (esophagus, 211. bodily iieripheral centripetal, pal- ate, 213, 21 ». 223. bodily peripheral centripetal, I)r()state, 237. bodily peripheral centri|)etal, sali- vary glands, 233. bodily peripheral centripetal, skin, 215, 242,244, 245,240. bodily peripheral centripetal, cor- puscles of Meissner in, 230, 240, 241. bodily peripheral centri[ictal, Ruf- fini, 247, 24S, 240, 250. bodily peripheral cent ri]ietal. 7V(.s7- zi'lh'ii (.Merkel). 22(), 221. bodily peripheral centripetal, tu- liuli seminifei'i. 235. bodily peripheral centripetal, villi, 232. lower motor. 41, 883, 577. lower motor, lesion of. 103!). lower motor, relation to upper motor neurones, 1030. lower motor, segmental arrange- ment in cord, 884. olfactory, groups of. 501 502. Neuropil. 271-273. Xeuropodien, 79. Neuroporns. SH. Neuros(mu's (Held), 50, 144, 145, 156, HI, 82, 83. Neurospongium (Mis). 106. Neurotome, 1!)5. ^SA" I SUBJECT INDKX. 1113 NissI bodies (stainiiblc substiinci'). 105-1:54, see also Tigroid. Nissl's classilicdtioti of cells. 115-126. iiu'thod, 45. l()(i, -242. 2415. Nil. cluiiiiini incdii, 1S7, 11MK oeuloriiotorii, ilccussatioii of, 945, olfactoi'ii. 754. spinak's, description of, IS.), 323- 325. si)iimles, gaiifjlia of, SCMJ. spinalcs, radix dorsalis. 281. 5MM». spinalcs, radix dorsalis. aseeiiding limb of bifurcation. tUH. 4(iH. spinalcs. radix dorsalis, collaterals. »(>.-». 470-475. spinalcs. radix dorsalis. collaterals. elnssifieation of, 473-475. spinalcs, radix dorsalis, descending limb of l)ifurcation. !{(>+. 468. spinalcs. radix dorsalis, fiijres of, 2«4, »(>S. 447, 465-460. spinalcs, radix vcntralis, ;J0(». spinalcs. rami of, \Ho. subscapulares. 1S(». supraclavii'ularcs. 1 SJ>. Nolle of Hanvier, 32, 41. Noyau 7Hosficafeur,svc Nucleus nio- torius princejjs N. trigemini. semilinidirc ile Flechsig, 674. Nuclei arciformes, see Nuclei arcuati. arcuati, »7(>. 5(i5. SOJ). 674. cor|ioris mannnillaris, 76i), 400, 4))L funiculi lateralis. ,'{S2, 402. intcrmcdio-latoralcs. 013, 'jSo, 58(». medialcs, 913, ,'>sr>, r>S({. inotorii N. trigemini. 313, 033. .")'.» 7, .>J)S. of tlmlanuis, Nissl's study of, 676. 679. nioiorii minores N. trigemini, 313, 933, r»{)7. .'lUS. N. acnstici, s(^c Nuclei N. cochlea' and Nuclei X. vestiiiuli. N. cochlea", 310, 311. 312. 3lH. 323, 3(57, 372, 547, 549. 407. 410,411.415,418. Nuclei (if <'enlral acoustic path. .■>55. of cervical eidargenicnt, 014, ."iSo. of luml)ar enlargement, r>.SO. of the reticular zone. 677. (i70. pontis. 3S0. tcrminales nervi trigemini. Iihra> arcuata> interna' from, 422. Nucleus ala- cinerea-, 3(M>, 31s, 372, 377, 470, 4(K. 621-(i24. and)iginis. 320. 407, 020. amygdala'. 4({7. amygdalil'ormis, .see Nucleus amyg- dala-. anterior thalami. 673. 443. caudatu.s. 030. (i3S. centralis inferior. 577. 322, 403, 40.-». 614. centralis nu'dius. 577. 062.073. centralis superior, 315.321,322, 3S(5, 579, 404, 405, 414, 420, 614. cerebello-acusticus, 505, 511, 633. coUicnli inferiori.s. 315, 380, 579, H6H. 53{>. colliculi inferioris. relation to lat- eral lemniscus, 868. commissui'a' postcrioris, see Nu- cleus fasciculi longitudinalis metlialis. conniussuralis, 3(>8, 320. 487, 400, 410, 625. 626. corporis gcuiculati lateralis. 814. corporis trapezoidei, 300, 545- 547. 854. 857. dentatus. 310. 308. 505, 302, 423, 424. 428. dentatus, connection with cortex of vermis. 424, 425. dorsalis (Stillingi. Clarkii), 8, 474, 559. 576. 581-583. 387. dorsalis. axones from, 740. enibolifornus, 423, 424. fasciculi longitudinalis medialis, 317. 380. 401. 415. fasligii. 511. 568, 575. 413. 423, 424. 852. fasligii. relation to Dciters" im- cleus, 636. -^««dSaaB»j»B«,- 11 u TlIK NP^IJVors SYSTEM. Ft Nuclfiis riiiiiculi ciiiioati, :U»S. :tO!>, »ls-:{2o. a;,-). :{,s-_», :{.s.->, .-):.<), ■)(;(», oCm, 40'i. I'liiiiciili (•iincali.tcrminiitioiiof nx- oncs from, 7^|. riiniciili .jriicilis, ;»»s, .'{IS-.'WO, .•{74.;{7.'>.;{s2-.'{,s4,rM!), SGO, 4(K{. funiculi j^racilis. injury to, TOM. funiculi ^niciiis, tcnniniitioii of ax- onos from, 741. funiculi Icrctis, 40.'{. funiculi vcniralis, (114. Klni)()sus, ilU'2. 4l»:{. 424. luii)L'nula', 775, H;il. hypo-llialamicu- (corpus Luysi), :iSL». .-)(;<». ,-)M(). 071. ()7;j. 437. impar, !(4;{. innominatus (von Hcclitcrew), sec Nucleus lateralis superior, intercaiato of Staderini, 1)26. lateralis anterior (Perlia), 944. lateralis inferior, 577. lateralis sujierior. 31 (J. 3*20-322, 57!». 4(M, 40.'>, 61(i, !)()!». i)7'2. lateralis thaliimi. (57:!. 443. leninisei lateralis. 314. 321, 322. 3(;?>. 3S2. 3S(J. 405. 420. S4(i. lemnisci lateralis, ini'er'ior and su- perior, Hill. S(i4. lentiformis. odi*. 711. 71:5. inaiiiiocellularis of medial nucleus, 081. incdialis thalanii. IM'-). 443. ininimns (von Hecliterew). 655. inotorius prince|)s N. triujeniini. 313. 320. 407, 411, iwij. 507. .')»S. mo. !):!5. N. abducentis. 312. 31S. 31J>, 407. 411, 410. 427. !»;{•,>. 947. N. cochleie dorsalis. S51. N.cochlea> ventralis. H4H. r)41. .>43, N. facialis. 21S. 312, 321, 322. 4(^7. 41«. o'Ml !»',".». N. facialis, motor filires from me- dial leninisc'iLs to, 1017. N. Klossoiiliarynjjens. 377. N. Iiypo;;lossi,"30». 31S-320. 32». 370.407, 411. :/.ni,im. N'ucleus N. Iiyjiofrlossi, motor fibres from me(lial leniiiiseus to, 1017. N. oculomolorii, 317. 321-324, 407, 941, 94:5, 003, r»04, 947, (>(Mi. X. oculomolorii, collaterals from fasciculus lonjj;itudinalis to, 7:21, \. trochlearis, 31«, 321, 322, 324, 4()7. X. trochlearis, collaterals from fas- ciculus iongitudinalis medialis to, 721, 400. X. vestihuli, li'27. X. vcstibidi lateralis (I)oiters), 312, 31S, .509, 5()H. 407, 411, 413, 410, 417, 41S. X. vestil)idi lateralis (Deiters). (i:{4. X. vestihuli lateralis, cells of, G;{4. X. vestibuli latei-alis, crosseil cen- tral vestibular jiatli, 6:57. N. vestii)uli lateralis, direct cen- tral vestibular path, 6:i7. X. vestibuli lateralis, fibres of , 6:i7. X. vcstibidi lateralis, path to cord fioin. 41.'). 410, 41S, 410,420, 959. X. vestibuli medialis. .310. 311, 3 IS. 3(»H. 507, 4(>7. 411, 410, 627. X. vestibuli spinalis (radicis de- scendenlis), 411, 627. X'. vestibuli superior (von Meclite- rew). 311. 312. 31S, 509, 407, 413.410, 41 s. (.:!(). of Darkschewitscli, 721. 724. 402, 4(;3. of Deiters. see Nucleus X. vestibuli lateralis, of Kdiiifjcr and W'estphal, see Xu- cleiis X. oculomotoi'ii. of metamere. 197, 127. of the middle line (Xissl). 077, 679. olivaris accessorius dorsalis, 310, 377. olivaris uocessorius medialis, 300, 310, :{2.{, 324, 370, 377. SUHJECT INDEX. 1115 Nucleus oliviiris iiiffr'ior. 17fi, tH)U- ;{iL», ti'i'.K :{7«. .ITT. CIO. olivaris supiTior, ;{!.'{, .'{S*2, .'{S({, 84:J, Ho], .•)44. oliviiris sii|)iM-i()r, filiiv syslcni to micleuif N.iit)(liicentis from, 422. olivaris siipcfior, iicilimcle of, i*o2, .'>4». posterior Miahuni. 440. pra-olivaris. 84:!. r>4.*S, H'u. railicis (ifscciidt'iitis N, trij,'('iniiii. s(>o Xiu'lci molorii iniiKiros X. trigL'iniiii. rcs])ii'atory. of ^lisslawsky, seo Nu- cleus funiculi vent rails, ret icularis tc<;nient i. ;{2*2, SHU, 570. 401. 4o:>, 420. 014. ruber. .'{17, ;{24, 070. niher, cross! ii^r tlescomling spinal sysleui from, i»72. semilunaris, 857, 858, .'i4», 843. Iractus solitarii, ;J10. SIO, 4r!t. 48(5, (;24-G2(;. Iractus spinalis \. tri<;:ciuini, .'{OS. .'{(«>, ;{i.'{. .'{'2o-:{22, .'{4;{, ;{4«, :{<:{, :{:.'>, 517, (54 1. vent rails tlialauii. 44S{. Y, .'{11. .'{IS, 507. Nucl's space, :{(J4. Niitrition theory (Golgi), 258. Oheir Schleiffi, 688, (592. Oherer Kern, (Burdaeii), 674. Oriilonto/oriiixki'ni of Darksclic- witscli, s(>e Nucl(Mis fasciciili lougitudinalis nieilialis. Oiiex, S72. Occipital cortex, fibres from su])erior collieulus to, 819. cortex, lesions in, 817. Oculomotor nerve, see Nn, oculomo- torii. Olfactory apparatus of the carp, 5(M). bulb, see IJuHms olfactorius. conduction jiatli. "cntral neurones of. 748. glomeruli, see (ilonu'rulus olfac- torius. Olfactory irranules, 750, 485. islands, 701, 4S7. 4hs. loiie. see liobus olfactorius. nerves, see N. oll'actorii. orgaiion.see Organon olfactoriuni. tract, see Tractus olfactorius. Olivary fascicidus, 954, 00!». Olive, inferioi, see Nucleus olivaris inferior, superior, see Nucleus olivaris su- perior. Ol in- 1, Strang, 955, 00J>. Operculum, .')(>4. ophthalmic vesicle, 1 IS. Optic chiasma, see Chiasma opti- cuui. uiM'vc, sec N. opt icus. neurones of higher orders, 782. paths, see Visual conduction paths, radiation, s.r iiadiatio oecipito- thalainica ((Jratloh'ti). thalamus, see Thalaiuus. tract, sec Tractus opticus. Organon olfactoriuni, 188. 157. s])irale (Corti). :{(J4. Orang-outang, motor localization in cerebral cortex of, 1000, <»:{.>. Osnuitic animals, 749. Pacinian corpuscles, 22.'{, 24.», 25.'{, :{.'>4, ,'59;!. ;!94, ;S96. Pain points, 25:5. Pallium. SO. extii'pation of motor areas in, 1023, (»4:). Pajiilla nervi optici, 784. ['ajiilla' vallata', 526. Paracentral lolmle, see Lobulus para- centralis. Paraj.hasia, 1078. Parapyknomoi'phous cells, 123, (»7. Paraxone, 270. l'ani.ri)H)'n, 90. i'ars basilaris fasciculi [)edunculo- niamniillaris. 772. basilaris pontis, .'{l."». niammillaris hypothalami, SO. optica hyiiolhalami, SO. V V, M \ 11 If. TllK xNKIlVOUS SYSTKM. I'jilli. I'l'iiiiliil (•(■i'cl)n)-ciirlii'c)|iiiiitMl. (i('cij>ilu-t('in|M)nil (I'l'dii'ii-corlicii- |M>iit:il. :ts(». I'cduiiclc, iiil't'iiiir, sec Corpus rcsli- foi'inc. iiii(>. Perinuclear zone of Apalliy. i)Ci, ,'»{). Peripheral ce fui^^al neurones, see Neurone, .,.eripherai<'enlr'ifu,i;al. nerves, components of, ))21. Periiendicuiar fissure, external, see Fissura parieto-occipitalis. Pes lii)>poeainpi, ^ Hip])()canipns, jiedunculi, see Jiasis pedunculi. Phosphorus, ed'ecis of, '2M. 1 70. Planum fil)rillare jirofundum, (J43. I'lexiis l.rucliialis, 1S«. ;J2r). cerviealis, IHH. Jl','"). cervieo-bnichialis. 1M(1, ;W5. coccygeus, 1M7, li'-i-'). lumhalis, 1H7, li'-i"). lumbo-sacralis, |H7. II'^S. |piidendus, IS7, 'oii't. pudendo-eandalis. 1S7. S'^r). sac ralis. IK 7, ;«"j. /'// ntitrhv, see (iyrus an),Mdaris, PneumoL'iisiric nerve, see N. va>,Mis. oisons, elTectS o >f. 'JH-i-'^HS, •^>!»."». Polioiuyelilis. spina! cord in, r)H4. I'olyaxones, HI, 4'J. 4.'$. Polymeric muscles, 201. Polystratilied cells of retina, 1K,\. i'ons (N'aroli), see Metencephaloii. I'onliculus, 37'i, .'{77. Posterior cereliral vesicle, HH. loii;;itudiual bundle, see Fascicu- lus lonj;i(udinaiis medialis. nuclei of tliaiamus, CTH. iijfaclory lolje, see Loiius olfactori- us. Post-mortem chan,<4'es in nerve cells, Postotic myotomes, !(2(). I'ra'cuneus, Pi.iie 1, 4. J'nfilor.'tiili'i LdnfiMiiidcL 720. !l(ii». Precentral sulcus of cerelirum. sec Sulcus pra'cent ralis. Primary optic centres, Ti'T. Primitive fibrils (Apathy). 272. sej;ments, lit"). Processus ci'relielli ad cei't'brum (Stilling). (mO, 4'_»S. i'rojection libres. (!()"). Profit ic luyotouu's. i)10. Prosencephalon. KJo. I'roto]iljismic commissure, HitO, r>71. conliiuiity, 7. |)roeesses, see Dendrites. Prozonal nerve trunks. 20!). VM\. 1:{H. i'salterium. see ("oinmissura hippo- campi. Pulviiiar. r.;!(i, OHl. 440. termination id' libres from. HIH. tcrinination of i2 of licydi;;, '~»7:i. l'ii|iil. rclli'N ((mtiiiclidii liiiiis cells, Vi'.i, 70. Pyriiinidiil ImukIIcs, set- Fasciculi cL-rclu'D-spiiiiilcs. cflls. r,', (is, ('.!», 75, SS, :{7, !I7(!, ((LM). tiaci.scc l''asciciilicci'clini-spiimlcs. rynimids, nntcrior. sec I'yiainis (me- dulla' (il)li)iipila'). (lecussatiiiii of, see Decu.-salio py- rainiduin. I'yraniis (ineilulla' (ilil(>ii;,'ata'). .'U>S- 31'i, ;{«s, :{7:», imm). Quadrice|is leiiKH'is muscle, nucleus (if, !»05, :>s;{. Qiiiidi'ijjeuiiual liodies, see Coi'poni quadrigemiiia. Radial io lorpdris callosi, 1054. (icci pile 1-1 lialaiuica (tii'alioleti), H14, H'2-2, s-s.i, :ti2. :ti'.i. (icci[iit()-t lialamica (( i lat iolel i). end- ing of libres of, s-2-,>. H',>:',, .^'Js. Kudic'os nervorum eereliraliuui, see corresponding nerves. I{adix descendeus (moscncopbalica) N. trigeniini. see N. trigemi- inis. dorsalis, 5.5i). l{»4-5!(>0, :!:!:{. :541. (lorsalis, developmenl of. IHl. postei'ior. see [\adix (lorsalis. ventral is. .SK5. lidiiilschlilir of His. see Marginal veil. Uundzellen of sensory nucleus of tri- geminus. 042. lidii/cnliirn. see Uliombelicepliah)!!. React idii at a distance, '")7. Recessus geuiculi, JM). • infundiliuli, *M). mammillaris, JM). utriculi, 8<»1. Rectus abdominis, nerve endings in. 8i)4. i!ed nucleus, see Nucleus ruber. Regeneration of nerve iibres, '245. Regio subthiilamicii, see llypothala- nnis. sul>tbalaunca, layers of, ti7i. {{eil. island of, see liisida. Resiiform body, see Corpus resli- forme. Reticular forunition, see Fornuitio reticidaris. Zone, nuclei of, (177. iielina, a.'»7. :{.'»S. '.UM). IliliiuKiiitliiil of corpus geiiiculatuin liiterale, 7!K lietina, bipolar cells of. 5|:i. comjiarison with other sense or- gans, 541. ganglion cells of, 7^1!. liiyers of. 5;i:i. 7(S4, .'»'_'{). origin of, 1!S7. rods and cones of, 5:(5. Retraction theory, 1(K». Rhineiieephalon, 74H. divisions of, 751, 754. Uhoudiencephalon, lower motor neu- rones of, i)15. Ricin poisoning, '•2!t7, 15JJ. h'ii'scii/ii/i(tiiiiilcii:rll(ii (Ret/), 078, Rolando, fissure of, see Sidcus cen- tralis Rolando, substantia gelatinosa of. see Nu- elcns tractus sjiinalis nervi tri- geniini. Roller's nucleus, !)2(). loiof, ganglion of. se(> Nucleus fas- tigii. Roots of spinal nerves, see Radix ventralis, Radix dorsalis. of spinal nerves, groups of fibres in, !»01. Rostrum corporis callosi, 1051!. h'liban dc IhiU ^ee Lemniscus. corficdl, see Cortical lemiusciis. iiifericnr, see I,euiniscus lateralis. sujwrU'ur, (i80. (W'i. Ruflini, nerve endings of, 'HiS, 247, 24{>, 250. v\ n % V \( ^ ins TIIK Ni;i{V()(S SYSTMM. I i 1 Siicnil nucleus, si'c Nucleus ilnisulis. Siirtoriiis muscle, nerve emlin^js in, HIM. Sciilii tynipani. 'U>2. vcstihnli. M'2. S<'ai'|iii's K'H'K'I'"'". ■■<'''' ("iinfjlidu ves- tibulan>. Srlidlciifiiniiii/tr h'iirpiT (von 'I'.schiscli), «74. St'hnllzi'llin (von iMouakow). KCiO. Sdiizaxones, H2, 40. Schleift!. .sen lieninisciis. Schleiff aiiH tiem oln'rcn Zwcthi'iyel, 4:1.-,. Schull/.e'scoinnui.lilMJ. :J{>,"»-2yH, 44H- 4.'51. 454-47.'). Scisst.rs of the brain (Stilling), 42H. Sclerotome, l!)<). 1*^7. Sderozone. "JOH. Secondary def^eueratioii, .see Degen- eration, Wallvrian. degeneration in i)\raniidal tract, lOUI. <54I. degeneration of motor fibres after cerebral lesion. <>43. Segmentation of body. 1!):!. Segments of spinal cord, function of, !)0a. Si'/is/thiirfiKUif/ifil of corpus genicii- latuni laterale, 7!)8. Seitenliuie, see Jjuteral line. SeifUehi' f/reiizficfn'cht der (/rniieit Siihsfdtiz.sw Fasciculus lateralis limitans. Semi-decussation in optic chiasm. 786. Sense centres, cortical, lesions of. 1074. Sensory components of cerel)ral nerves. i(24. .'»{>•_>. conduction pal lis to central gyri. 704. conduction paths to cortex, 7i{4. cutaneous areas, ;i;{0-:{4l», 188, 189, i5>o-i»r>. culane7, 198, 199, 200. Sensory ganglia, see Oanglia, sensory, nerve lilires, development of, 181, inicleiis of .\. trigendnus. 042. optic centres. 7i*7. iystcms. !. II, 111 of Klechsig, 785, 4«({-4«8. .Septo-nmrginal iaindle of Mruce and .Muir, see Trimit/le mfdiiiii of (iombaidt et Philippe. .Septum pellucidiMn. I'late I. .'t. Sheath of llenle, H(». Side fibrils, 12,41, iW, .'>7. 8i)2. Silent areas of cerebral cortex, 1071. .Small-celled hyjioglossal nucleus of Holler. \m\. Sail If It .s (( hstan z, 574. Solitary binidle, see Tractus sf.lita- rius. .Somu'sthetii' area of the cortex, (567. conduction path, rimtnie of, 731), 409-471. path to cerebrum l)y cerebellum, (147. Sonuitic t'omponeuts of peripheral nerves, {)2\. Sonuitofhrouie cells. 11."), 121,07,08. Somatoplasm, 'tli, 55. Somites, 88. Space, |)erfoi'ated, anterior, see Stib- stantia perforata anterior. Special senses, I'cntres for, see Sense centres. Specific energy, 2.')4. 2.').5. Spinal ac<'essory nerve, see N. acces- sorius. coril. bulb or uuirrow, see Medulla s|)inalis. cord, motor localization in, 899. nci-ves. see Nn. sjiinales. neurone system from formatio re- ticularis, 962. roots, groups of fibres in, 901. Spoiigiol)lasts. 106, 99. T);}?. Stereognostic sense, 1077. Slichochrome cells, 117, 121, 70, 71. Slid (les wciliolen Knichikkers, 875. Sti-ato biancocinereo profundo, 809. biancocinere./ superticiale, 809. /"- srn.IK{T INDKX. in Slialiiiii iilhiiiii tiicdjiiin, HDjI. iill)uiii |ii'(iriiiiiliiiii, HO!), ('iilcitriiiiiin, ll).")!). KloliHTiildsiiiii (iT olfactory l)ull), ?.*),■), 47 s. f;risciim cciiiriili'. .'{15-317, ill*,)- 324, 3M«, r,T!», HOii, ,s;)i. KiiM'uiii (Milliciili sii|)(ii(.ris, 800. HflH, 'trt't-ooH. ),'risiMmiofolt'acton Imlli. 75.'), 47S. griscimi |iroriiiiiluiii. H(»!), ,'»1H. iiHcroliviHv ' lciiiiiisris, H()8, 809. Stria iiic'diillaiis, 774. tncdnllai'is tlialaiiii. rclatimi to lii|)- pocaiiipus ami liasal Lraiifjlia, 774, 407. olfa<'toria lateralis. 7.")(). 7.')<». olfactoria mcilialis. V.\S. Stria' iicustica'. see Stfia- nicdiiljarcs. iiifdidliires (simi aciistic;i'). 3<55). 372, r>3(J, .'>4o, r)r);}, 840. Stripe ot Vic(id'Azyr, ({3S. Strychiiiiio, cITecfs of, 28."). Siilicdiiscioiis iiiipidscs. '^oO. Suhstaiitiii alba of cord, stinuiiatioii of. C40. gelat iiiosa. .300, 300, 403, 41 7, 41!>, 4,(», 041. gclatiiiusa eoiitralis, 373. gelat iiiosa (Uolaiidi). sec Nucleus tnictiis spinalis ncrvi trigeiiiini. grise.1, 40.>, 414, 410, 473. nigra, 31<», 317. 3.S0, r)7!». nigra, termination of tlninih fibres in, 1028. perforata anterior. .')0(K ■ Snbtlialaniic tegmental region. s,>e Tegnie-ituni and llypotlialamiis. Sulci temporales transversi, (538. Sulcus centralis dJolandi). (5.33. eiiiguli. 02. eingidi. pars nuirginulis, 02. cinguli, pars subfronlalis, 02. frontalis inferior, (538. frontalis superior, 03H. Iiypollialainicus (Monroi). 0(K parolfjieloriiis posterior, ~,M. pra'cent rails. 033. riiinencepliali inferior, 7t'>3, 47(1, 477. semilunaris. 7.')2. spiralis. 3(52. subpariclalis. 02. temporalis superior. (538. Superficial arched fibres, sec Kibra- arcuala' externa', opiio path, 821. Superior coUiculus, see f'ollieulus superior, lemniscus, ()88. (i!»2. medullary velum, see Velum med- ull.'ire anierius. (dive, see Nucleus olivaris superior, olivary complex. 84:?. Supranuirgiual gyrus, see (iyrus suprainarginalis. Sylvian aqueduct, see Aquediictus cerebri, fissure. see i-'issura cerebri lateralis, fossa, sec I''ossa cereliri lateralis. Sympathetic ganglia, 1!>0. Sympatliieus. ,330. Si/n/f/t'nc('/i/i(i/i>-r('rfl)i'!/are non-eru- cidfinn. 741. inPiintnicinii) (liinri'phdlo-pnlUn. turn. 701. (ni'xi-on iciin, ) mycli'iivcpliii Ui-pnUi- olc. 701. {neuron iriini) nnjelenceplid/o-fhn- Unnieum, 714. ! ► ll-ja TIIK NKIlVol'S SYSTKM. Sj/x/i-mii {iifiinniiriiiii) .ijn'iio • ri-ir- 'I'lirchholil of ImIhikI, sen Ijtiii'ii in. Iwlliiri' mi/ni/ii/irn/r nuijiiiir/i- siilii'. '•'(/'■, 'Ml vahir, •,>.",;!. (ni'iinininiiin ■•'/iin•"•. 17, KKl. lOS, 1||, 112, Hwm ri ii/m-lii/rrdli' sii/im'iix, 500. TubcH, (Icgcncraticiiis in, !24H.a-14, 254, 42H, 4:i«. Tn'iiia cliorioiilfii, 774, 45Mt. tiialiiiiii, 774, 4JM5. 'I'api'liiin. .'>22, 5'_»:{, 10r)4, 1007. 'rasli'-lnuls, si'c ('iilyciili ;,Mistiili)rii, Titxtzi'lli'iinntX '/'ii.s/iiiriii.-( Mcrkol, Hi) t!2l. 'I'aiitniiicric iiciii'niics, sec NiMiroiics, taiitiiiiit'ric. 'I'pgiiu'iital Imiiillt' i>f Iciiliforin iiii- clt'iis, 074. Ijundle ( tlialanius, (i74. prujcciiiin, {M). 'J'cgnu'nluni, dccussalicins of, 773, 492. paths U), 6($H. Telencephalon, lo!). S{>. motor ni'uroiics of, !l7o. 'IVloileniirion. 41. S',>. Telodoiidrions of inot(jr axone, HOS, 574. Temporal ccrcln'o-corl icoponlal path, 1045, 104u. pyri, auditory fihre.'i cndinuf in, 878. Tempora/c (irons/i ini rinili- liri'ivkcii- bahn, .«ec Temporal cerebro-cor- ti<'opontal pat) liii'cltHjihiirv {V 7.')f(. Testes, see C'"'' vrior. Tctanus-t' ., of. I, SI. 1Si2, | 303. Thalamus, ^... l)undl(^ fi'om nucleus rulier to, 42H nucleus of, 073. (170, 078, 07!). ventro-lateral nuclei of. 569, T/hifnnnisiiiaasir (Tschcrmak), 682. 127, I2)», 1!10, i:<2, i:}4, 155. l.-ifj, ((4. ((.'>. 7.'>. ;». Tongue, origin of muscles of, ,')JM, 1)20. Touch points, 25:t, 1 ract or tracts, antcro-laterai ascend- ing, see Faseicnlus ventro-hitc- ralis. Tract, comma, see ( 'ommaof Scliultzo and Schult/e's coiuiiui. crossed or lateral pyranddal. see I'"asciculus cerchro-spinalis late- ralis. direct cerelicllar, see Fasciculus spiiio-cercliellaris dorso- lateral is. direct pyranddal, see Faseieidus cereliro-spinalis veniralis. of liiirdacli, see Fasciculus cuneii- tus, of lillct. see Lemniscus. of (lowers, see I'''as<'icuius cerehro- spimiles suiierlh ialis. of (ioll, see Fasciculus gracilis. of liissancr see l*'asciculus dorso- latcialis Lissaueri. oll'actcry, see Tractus olfaclorius. optic, see Tractus opticus. pyramidal, see Fasciculi cerehro- spinales. Tractus oi)ticus. 7!H!, .»09. 798. olfactoi'ius lateralis. 47M. olfaclorius medialis, 47.H. pe(lunculaiis trausvei'sus, 807. solilHiius, 102, :{09.:U2,:ms-:{20, .•12(J, .'{27. :{7«. 48.5, 407. 020. spinalis X. trigemini, SON, .'{09, 311, 320-:{22, 329. 34(>, 377, 391. 392, 407. 411-413, 41«, 417.419.421.422. tegnu'nto-ccrcbellaris (Fdinger), 664. Thnlamusschale (Tschermak), 682. j Tra{>e7.ium, sec Corpus trapezoideum. HUh.lK(T INDKX. I -J I I Trii|ic/ui(|iil liody, SCO ('(ir|iiis trapf /oiiliMiiii. Tri)m;,'iiliir piitli uf llflwcfr. !l.>J. Triiiiifilf ni('ili(in of (Idmliimll el I'liilippc, .t.VJ-.|r)7. Tiicc|is rriiisclr, iici'vi' t'!i(liii^;s in, N))4 Trip'inimil irtvc. st'c N. Irii^ciiiimi.s iidiroiicM, (Ttitnil ci'iiliiiiiliil. (HI. Ttip'iniiMis. film's to r.inimlio \v\U;- uliiris fnirii ti'i-r>iiiiiil nucleus of, Ti>H. 4«4. 4«J.V Tri",'(inuni Icninisci. ((Hd, H47. Trochlciir nerve, see N. tmclilearis. Trophic centres, 'l'H\. Tro|iliicity. theories of. :i()ti ;|||. Tiiincus corporis callosi, K).");!. Trunk iireii of motor cortex, !»!)!», (}(}.*{. Tiilier cinereiini, \){). Tuliercle, acoustic, see Nucleus N. C()(;hica' (lorsalis. cuneate,seeTulierculuincuneatuni. 1)1" optic thalamus, anterior, sue Nucleus anterior thalaini. ol' optic thalamus, [losterior, see I'uh inar. TiiliciriilcH 7. I'triculus, .'Mn. I Vapil nucleus, see Xucleus aKc cin- erea-. I V'ajfus nerve, see N. vagus. I Vallate pajiilla', see Papilla- valiatu'. J Valve of N'icussens, see Velum medul- lare aiiterius. Vascular segment, 11(0. ' Vater, corpuscles of, see I'acinian ccirpuscles. X'elum medullare anterius, ;172, medullai'y, superior, see Velum nu'.'{. quart us, ;{()». 31 s, 372. Ventro-laterai cell-group of anterior horn, see Neurones, lower motor, lateral tract, ascending, see Fas- ciculus ventro-hiteralis superfi- cialis. Veratrin, effects of, 28;3, 171. Vermiform process, see Vennis. Vernus, oOH. ,')7.'). connection of nuclei of roof with, 424, 425. 1122 TlIK XEKVors SVSTKM. I) ' \.st,lM,Io-s|,inal pathj>r,!». , WalUTinn .legonemtion, see Deiren- \ le-i i|-A/,vr. huii.lle ,.f. see Fasei.Mi- { eiatio,,. .ee-mdarv or \Vall..,ian lus Ihalaino-inainmiilaris (Vie.| i il„etri..e and il,e neuroiie-eoiiccMt" (1 Azyr). 22V). Villi, choroidal, see IMexus eliorioi- i Warm points. 2'}:i. ''i'"^- ; Wernicke's field. H14. \ iseeral motor and sensory oonipo- I liendanopie pupillary sign, 882. neiitsof periplieral nerves. !)21. | Wliite eolunins of cord, see Kiinic- Visiial area of cortex cerebri, lesions i uli. of. 817. centres. contieclioH with cord and bulb.see Visual coiidiiction paths, conduction pat lis, o'lU. .VJ'i, ."j.'J'J. commissure of cord, sec Commis- suia alba, matter of ceroliral hemispheres, see '. 'entnim semiovale. Worm, see N'ermis. conduction path' ^ntrifugal fibres "•"■ ^•^~- Zvrt^t rente arre.ssonsr/ie liundel ^von Jk'chterew). ()84. Zona incorta, 671, G73. 437. reticularis (Gitlerschiehl), 438, conduction paths, decussation in. .'.30. liirection. cortical area for, i)!»8, sense area, primarv. 8*,>L', X'i'i. N'ital staining, see Khrlich's vital staining. Vurderdraiiyretst, 374. G77. Zone F (Munk). removal of, (;!)7. Zone inotriee (Charcot ). !(7,'). of confusion, KD;""), (»32. L I w T i