SECTION OF SYMPATHETIC NERVES. 655 



SOME FEATURES OF THE STRUCTURE OF SYMPATHETIC NERVE CELLS. 



Our knowledge of the minute structure of sympathetic nerve cells 

 has been greatly furthered by the use of the Golgi and methylene-blue 

 methods of staining. 1 We need, however, only mention those points 

 which bear upon the experimental results. 



In mammals, the sympathetic nerve cell has a single nerve fibre 

 process and a considerable number of dendrons. In this it resembles 

 most of the nerve-cells of the central nervous system; but in most 

 cases, at any rate, a characteristic appearance is given it by the arrange- 

 ment of the dendrons. 



In amphibia and in some other lower vertebrates, dendrons are not 

 always present. Thus the spiral cells, discovered by Beale and Arnold, 

 have no dendrons, the straight process is the nerve fibre. 



In such sympathetic ganglia as have been investigated, fine nerve 

 fibres are found penetrating the ganglion and ending in it, in more or 

 less close relation with the nerve cells. In amphibia, such fibres form the 

 spiral " process " of the pyriform cells, and end in fine branches under- 

 neath the cell capsule. In some cases the entering nerve fibres divide 

 and end in connection with more than one nerve cell. In the 

 sympathetic chain of birds and mammals a fibre may be seen giving off 

 a branch to end in a ganglion, and then continuing on its way, presum- 

 ably to end in another ganglion. We may reasonably take the fibres 

 ending in the ganglion to be the pre-ganglionic fibres, and the fibres 

 given off by the nerve cells to be the post-ganglionic fibres, which we 

 have described on experimental grounds. So far, the histological and the 

 physiological results are plainly in harmony. 



THE DEGREE OF PERMANENCE OF THE EFFECTS CAUSED BY SECTION OF 



SYMPATHETIC NERVES. 



Speaking generally, it may be said that on section of all, or of the 

 great majority of sympathetic nerves to a tissue, paralytic effects may 

 be observed in a few seconds. But in anaesthetised animals, at any rate, 

 the degree of paralysis immediately following the section differs widely 

 in different cases. It is probable that when the symptoms develop 

 slowly, there is some condition of stimulation, either of the cut ends of 

 the nerve fibres or of their peripheral terminations, which only slowly 

 dies out. When vaso-constrictor fibres are cut, the extent of the 

 flushing will depend in part upon the arterial blood pressure. And in 

 cases of section of the majority only of the sympathetic fibres to a tissue, 

 the degree of paralysis will, of course, depend upon the number and 

 activity of the uncut fibres. 



These effects may be maximal in a few seconds after section of the 



1 Kolliker, Sitzungsb. d. phys.-med. Gesellsch. zu Wurzburg, 1889 ; Verhandl. d. naturf. 

 Gesellsch. in Wien, 1892 ; Sitzungsb. d. phys.-med. Gesellsch. zu Wurzburg, 1894 ; Wien. 

 klin. Wchnschr., 1894, No. 40-41. Smirnow, Arch. f. mikr. Anat., Bonn, 1890, Bd. 

 xxxv. S. 407. Cajal, Arch. f. Anat. u. Entwcklngsgesch. , Leipzig, 1893, S. 319; "Atlas d. 

 pathol. Histologie d. Nerven system," Berlin, 1895, Lief. 4. v. Gehuchten, Cellule, Louvain, 

 tomeviii. p. 83 ; Anat. Anz., Jena, 1893, Bd. viii. Retzius, Biol. Untersuch., Stockholm, 

 1892, N.F., Bd. iii. Sala, Arch. ital. de biol., Turin, 1893, tome xviii. p. 439. Lenhosselc, 

 "Beitr. z. Histol. des Nervensystems, u.s.w.," Wiesbaden, 1894. A. S. Dogiel, Arch. f. 

 mikr. Anat., Bonn, 1895, Bd. xlvi. S. 305. Arnstein and Ploschko, Anat. Anz., Jena, 

 1897, Bd. xiii. S. 17. Other references will be found in Kolliker, " Handbuch d. 

 Gewebelehre," 1896, Bd. ii. S. 870, and in Huber, Journ. Comp. Neurol., 1897, vol. vii. 



