584 



PHYSIOLOGY. 



by chromatolysis of the cells of Deiters's nucleus on 

 the same side as the lesion, and to render it prob- 

 able therefore that the fibers of the antero-lateral 

 descending tract are derived from the cells of that 

 nucleus, and not from the cerebellum. 



Nicolas Alberto Barbieri has found that in cats, 

 dogs, rabbits, and guinea pigs the unipolar or bi- 

 polar cells of the spinal ganglia do not form any 

 connection with the nerve tubes of the posterior 

 roots. These cells may be dissolved by chemical 

 means without altering the form, contour, or even 

 the continuity of the nerve fibers of the posterior 

 roots. Each spinal ganglion contains from 200 to 

 f>00 cells, while the number of nerve fibers that 

 traverse the same ganglion is from 1,000 to 3,000. 

 This number is about double that of the nerve 

 libers found in the anterior roots, which varies 

 from 500 to 1,500. All the nerves of spinal origin 

 contain a far larger number of fibers derived from 

 the posterior than from the anterior root. Besides 

 the ordinary fibers of the posterior roots, others 

 of smaller diameter may be found enveloped by 

 a thinner sheet of connective tissue, with less 

 granular, more transparent, and almost limpid 

 contents. The medullary and encephalic origin of 

 the sympathetic is established to the satisfaction 

 of the author by examinations of the branching 

 and relations of the small fibers which are de- 

 scribed in the paper. The cells of the spinal gan- 

 glia are found to be cells of the sympathetic from 

 which the rami communicantes proceed. The 

 whole number of the nerve fibers of all the roots 

 of the spinal nerves is in the rabbit about 70,000, 

 a number too small tor the supply of all the tissues 

 of the animal, while it is too large to come into 

 relation with the surface of section of the collet 

 da bulbe. The posterior roots spring from the 

 posterior collateral fissure by small fasciculi. Each 

 fasciculus contains a certain number of nerve 

 libers, and several fasciculi form a root, and sev- 

 eral roots form a radicular root. Two or three 

 radicular nerves separated from one another by the 

 spinal dura mater are found on the superior sur- 

 face of each spinal ganglion. The posterior roots 

 penetrate the ganglion largely provided with con- 

 nective tissue, or in the condition of a nerve. The 

 anterior roots which arise from the ventral collat- 

 eral grooves have an analogous origin, and unite 

 externally and below the ganglion with the pos- 

 terior radicular nerves to form the mixed periph- 

 eric or proto nerve. The mixed peripheric nerve 

 of each pair of spinal nerves, after having given 

 origin to the small meningeal branch, divides into 

 two branches, the one anterior and large, the other 

 posterior and small. 



It has been observed that after reunion of a di- 

 vided nerve by means of suture function may 

 return sooner or later, and that this restoration 

 of function implies not only simple return of sensa- 

 tion and the capacity to make voluntary move- 

 ments, but also the re-establishment of complete 

 localization of sensation and of co-ordination of 

 movements. Care is usually given in suturing 

 divided nerves to bring the two segments into as 

 close an approximation as possible to their old re- 

 lationship. Thus the perfect recovery of localized 

 and co-ordinated functions might perhaps be due 

 to a majority of the fibers being so placed in a 

 position for a union of corresponding ends to be 

 effected. This subject has been recently investi- 

 iMicd by Dr. Robert Kennedy, of Edinburgh, in 

 three experiments on dogs, in which the sciatic 

 nerve was divided at the level of the trochanter, 

 ami in two of them rotated before suture to the 

 extent of a semicircle, while in the third experi- 

 ment accurate coaptation by suture in normal 

 position was effected. In the matter of recovery 



of function, the throe experiments followed a prac- 

 tically identical course. Under microscopical ex- 

 amination the central segments showed the char- 

 acters of the normal sciatic nerve with the excep- 

 tion that the lymphatic spaces were somewhat dis- 

 tended. The peripheral segments agreed in show- 

 ing no old nerve fibers in any part examined 

 either close to the seat of reunion or in the ter- 

 minal divisions of the nerve. In their place were 

 abundant young nerve fibers with well-defined 

 characters. Lying between the young nerve fibers 

 were degenerated remains of the old fibers, show- 

 ing that Wallerian degeneration had taken place. 

 The cicatricial segments were also all three prac- 

 tically identical in structure. In no case could 

 continuity of nerve fibers from the central to the 

 peripheral segment be traced. The author's con- 

 clusions were (1) that after section and imme- 

 diate coaptation of a nerve restoration of con- 

 ductivity and of voluntary function may be ef- 

 fected in a few days; (2) that this early restora- 

 tion of conductivity need not be the result of the 

 reunion of the old nerve fibers that is, reunion 

 by so-called first intention, or without Wallerian 

 degeneration, but may be the result of regenera- 

 tion of young nerve fibers in the peripheral seg- 

 ment; (3) that voluntary co-ordinated move- 

 ments are regained equally soon, whether the two 

 ends of the divided nerve are united as accurately 

 as possible, so as to bring the corresponding ends 

 of the nerve fibers into as near contact as can be 

 attained, or whether, previously to reunion, the 

 peripheral segment is twisted so that when united 

 to the central segment noncorresponding ends of 

 the nerve fibers are brought into contact; (4) that 

 in the latter case it is left doubtful whether the 

 restoration of function is due to the re-establish- 

 ment of the old paths by decussation in the nerve 

 cicatrix or to the reunion of ends of nerve fibers 

 which do not correspond but which happen to be 

 brought into apposition; (5) that in suturing a 

 divided nerve no trouble need be taken to secure 

 the coaptation of the two segments in the old 

 relationship, for the simple approximation of the 

 two ends, no matter in what relationship, seems 

 to be all that is required. 



In experiments on the work of the spinal nerv- 

 ous centers Mile. J. loteyko has found that the 

 marrow 7 has double the power of resistance to 

 fatigue possessed by the terminal organs giving 

 twice the work in response to the same excita- 

 tion; and. second, that it is capable of remain 

 ing excited four times as long as the muscle with- 

 out betraying any sign of fatigue. In short, t lie- 

 results obtained by the author indicate a great 

 power of resistance in the special nervous centers 

 and go to show that they are able to furnis 1 

 without fatigue, an amount of work at lea-1 foi 

 times more considerable than the terminal a 

 paratus. 



From studies made upon rabbits, it is co 

 eluded by Ivor LI. Tuckett that after section 

 the vagus nerve all the fibers will in time recover 

 their function: that the recovery is more rapid 

 and probably more complete in the case of fibers 

 supplying striated muscle than of those supply- 

 ing cardiac or unstriated muscle; that the in- 

 hibitory lihcrs recover function at lea-t a- 

 rapidly as the motor fibers: that the recovered 

 function of the '" autonomic " fiber is even at the 

 end of three years less than normal. 



Prof. Hitzig, of Halle, discussing, in a Iln.irli- 

 lings Jackson lecture before the Neurological 

 Society, the localization of functions in definite 

 areas of the cortex of the brain, advocated tin- 

 view that such centers exist, and further con- 

 tended that two sets of motor centers might be 



