432 



SYMPATHETIC NERVE. 



them as being destitute of a sheath, naked, 

 transparent, almost gelatinous, as presenting 

 a number of longitudinal streaks, and as break- 

 ing up into delicate fibrils, which in their course 

 present oval dilatations or swellings, and have 

 moreover a number of round or oval cor- 

 puscles arranged upon them at intervals- 

 Apparently, the same structures have been 

 described by Henle under the name of "gela- 

 tinous fibres." According to him they are 

 flat homogeneous fibres, measuring from the 

 0-002'" to the 0-003'" in diameter, and cha- 

 racterised by the presence of numerous nuclei, 

 some round, others oval, their long diameter 

 being directed in the longitudinal axis of the 

 fibre. They are dissolved by acetic acid, the 

 nucleus becoming at the same time more dis- 

 tinct. The fibres in question are well seen in 

 the branches of the sympathetic which go to 

 the spleen or kidney in the sheep or ox, as 

 well as in the trunk of the sympathetic nerve 

 itself. In the former situations they appear 

 as a more or less transparent, slightly granular, 

 pale mass, and marked by indistinct longitudinal 

 lines into fibres presenting a diameter of about 

 T _j__th to -jo-jTT 1 ' 1 f an i ncn > and characterised 

 by the presence of round, oval, or elongated 

 nuclei. On the addition of acetic acid they swell 

 out, becoming perfectly transparent and in- 

 distinct, while at the same time the nuclei are 

 brought more clearly into view. When treated 

 with tartaric or citric acid, the effect produced 

 upon them is much the same : solution of 

 soda also causes them to swell out and be- 

 come indistinct, the nuclei being at the same 

 time also rendered more or less indistinct. 

 The nuclei generally measure about the 4u 1 ,, th 

 to the -oV^th of an inch in length, and about 

 __L_th~to the ^TTTrth f an inc 'h in breadth, 

 presenting the same characters and behaving 

 towards reagents in [the same manner as 

 the nuclei occurring in most other tissues. 

 They are much softer than the tubular fibres, 

 and are not easily separated from one another. 

 In some parts of the peripheral branches of the 

 sympathetic these fibres present a much smaller 

 diameter, measuring about -go-Vot' 1 f an i ncn > 

 are finer and distinguished with difficulty from 

 the white fibrous tissue present. In the nerve 

 they are placed parallel to one another, and are 

 seen, when the preparation is pressed between 

 the glasses, running along each side of the 

 tubular fibres, which latter seem to be im- 

 bedded amongst them. They differ from the 

 tubular nerve-fibres in their flattened ap- 

 pearance, want of distinct margin, and in the 

 effects produced upon them by reagents, but 

 are especially characterised by the presence 

 of their nuclei. They are most abundant in 

 the more grey-looking branches of the sym- 

 pathetic, and seem to be the cause to which 

 this appearance is chiefly owing. Sometimes 

 when one of the smaller filaments of the 

 sympathetic is examined, it seems to be en- 

 tirely composed of these fibres, no tubular 

 nerve fibres being at first seen ; solution of 

 soda, however, which, as has been stated, 

 renders the gelatinous fibres transparent, brings 

 into view more or fewer fine tubular fibres. 



There can be no doubt that in many parts of 

 the sympathetic, especially in the branches 

 distributed to the arteries, the fibres of Hemak, 

 or gelatinous fibres, make up the greater portion 

 of their constituents, the tubular nerve fibres 

 existing only in comparatively small numbers 

 Sometimes more or less grey and white 

 bundles of fibre? may be seen running along- 

 side each other : such an arrangement is not 

 un frequently seen in the branches of com- 

 munication between the sympathetic anil the 

 spinal nerves. In such cases, while the white 

 chiefly or entirely consists of tubular nerve 

 fibres, the grey contains a large number of 

 gelatinous fibres, and always in addition to 

 these more or fewer fine tubular fibres. 



The gelatinous fibres are present in dif- 

 ferent proportion in different parts of the 

 sympathetic : they appear to be more abundant 

 in the neighbourhood of the ganglia than in 

 other parts and in the larger peripherical 

 branches they also exist in considerable pro- 

 portion, but in the final distribution of these 

 they either do not exist at all or only in small 

 number. They appear to be more abundant 

 in the sympathetic of the higher animals than 

 in that of the lower vertebrata. In mammals 

 and birds they exist in considerable quantity: 

 in amphibia, according to Kolliker, they are 

 present but only in small proportion. In 

 some fish, as in the common Ray, the sympa- 

 thetic ganglia and branches contain a very 

 large proportion of structures which agree 

 with the fibres of Remak in some respects, 

 such as in their relation to the ganglionic 

 corpuscles and tubular nerve fibres, as well as 

 by the presence of a number of small oval 

 nuclei ; they differ from them, however, in 

 not being so much affected by acetic acid and 

 in being firmer: the number of tubular fibres 

 occurring in the sympathetic is very small 

 compared with the number of these struc- 

 tures. 



3. The quantity of white fibrous tissue 

 present in the sympathetic trunk and branches 

 is generally considerable; the fibres are arranged 

 in the longitudinal direction for the most 

 part ; other fibres, which from their relation to 

 reagents appear to belong to the yellow elastic 

 tissue, encircle the nerve, binding together, as 

 it were, its constituents. After addition of 

 soda or acetic acid the circular fibres are 

 well seen ; at the parts where they occur 

 there is frequently observed a distinct con- 

 striction, the nerve being swollen out above 

 and below by the reagent applied. 



With respect to the nerve fibres occurring 

 in the sympathetic, many of them present 

 undoubtedly the same characters as those 

 occurring in the nerves of the cerebro-spinal 

 system. It has been maintained that the 

 sympathetic also contains fibres which differ 

 in their anatomical characters from the fibres 

 of which the latter class of nerves are com- 

 posed, and which have been termed organic 

 or vegetative nerve fibres. 



Ehrenberg appears to have regarded the 

 fine varicose tubular fibres which are present 

 in the sympathetic, as constituting the peculiar 



