558 FUNCTIONS OF THE CEREBRO -SPIN AL NERVOUS SYSTEM. 



ever long its course may be, is a loop arising in, and returning to, the same 

 cell. One of the fibres (a) is usually straight, penetrates into the interior 

 of the cell, and appears like a stalk to the cell; the other (b), which is 

 sometimes double at first, seems to arise from the exterior of the cell, and 

 winds spirally for two or three times round the former. Both fibres at first 

 resemble the cylinder-axis of ordinary nerve-fibres, and both may subse- 

 quently become dark-bordered, or remain pale, fibres. The spiral fibres 

 bear large oblong nuclei in their course. The descriptions given by Arnold 

 and Courvoisier are in accordance with that by Dr. Beale, except that 



FIG. 191. 



FIG. 192. 



FIG. 191. Stellate Nerve-cell, from the nucleus cervicis coriiu (posterior vesicular column) of a foetus 

 of six months X 420. 

 FIG. 192. Structure of Ganglionic Nerve-cell. A, According to Dr. Beale. B, According to Arnold. 



they state they have traced the straight fibre into the nucleus, and the 

 spiral fibre into a plexus on the exterior of the cell, but which may ulti- 

 mately be traced into the nucleolus (Fig. 192, B), so that the two fibres are 

 continuous with one another through the nucleus and nucleolus. The whole 

 cell is invested by a nucleated capsule of connective tissue, proceeding from 

 and continuous with the sheath of Schwann investing the nerve-fibres with 

 which it is in connection. 1 All our knowledge of the structure and endow- 

 ments of the gangliouic centres and nerve-trunks renders it probable that 

 they bear a complementary relation to each other; the Vesicular substance 

 having for its office to originate changes, which it is the function of the 

 Fibrous to conduct. 



445. Regeneration of Nervous Structure. If a nerve be divided by a sharp 

 instrument, and the ends placed in apposition, they will reunite, with com- 

 plete restoration of function. 2 The union is accomplished by the effusion of 

 gelatinous lymph, in which connective-tissue and elastic fibres form, by 



1 For a fuller description of these struct ures, see Quitin and Sharpey's Tntrod. to 

 Anat., p. cxliii ; Dr. Beale, Philosoph. Transact., 18(38, p. 543 ; Courvoisier, Cen- 

 trallilatt, No. 57, 18(17; Frantzel, Virchow's Atvliiv, 1867, Bd. xxxviii, p. 54'J; Ar- 

 nold, id., Bd. xli, ]>. 178; Schultze, lor. cit. 



2 CruickshiinU, 1776. Fontima, 1778. Michaolis, 1785. Haighton, Phil. Trans , 

 17'.">; Vnlpian, Lemons sur la Physiologie du Sysieme Nerveux, Paris, 18(111; For- 

 scher, Kanvicr, Cotnptes Kendus de I'Arademie des Sciences, 1873, p 4!1 ; Benecke, 

 Virchow's Archiv, 1873, Bd. Ivii, p. 4<.)ii ; Laveran, These de Strasbourg, quoted in 

 |)i'iiiar<iuay, De la Regeneration des Orgnnes et des Tissues, in which tlie various 

 views of Scliiff, Vulpian, Laiidry, Kanvier, Kolliker, and otliers are well given; 

 Hjelt-Otto, \"n-elio\v's Archiv, xix, p. 3-V-', and E. Oehl, Sul processo ill .lligenera- 

 zione dei .Nervi rccisi. Pavia, 1864, 8vo. 



