y 
THE CERVICAL SYMPATHETIC TRUNK 357 
ganglion and there appears to be no mechanism for a diffusion 
of incoming nerve impulses to all of the cells nor to all of the cells 
of a given function within the ganglion. 
Evidence furnished by nicotine and degeneration experiments 
shows that all the synapses between the pre- and post-ganglionic 
neurones on the pathways through the superior cervical ganglion 
are located in that ganglion. There are no ascending postgan- 
glionic fibers in the cervical portion of the sympathetic trunk and 
no preganglionic fibers are continued through the superior cervical 
ganglion into the branches of distribution. The pre-postgan- 
glionic synapses seem to be of two kinds: 1) pericellular networks 
and 2) relations established between the dendrites and axons 
in the intercellular plexus. One preganglionic fiber activates 
several post-ganglionic neurones. ‘The dendrites of the post- 
ganglionic neurones serve to increase the complexity of these 
relationships and may aid in bringing two or more neurones under 
the influence of a single axon as indicated in figure 15. 
LITERATURE CITED. 
ARNSTEIN, C. 1887 Die Methylenblaufairbung als histologische Methode. 
Anat. Anz., 2, p. 125. 
Aronson 1886 Beitrige zur Kenntniss der centralen und peripheren Nerven- 
endigungen. Inaugural Dissertation, Berlin, 1886. 
CARPENTER, F. W., AND CoNnEL, J. L. 1914 A study of ganglion cells in the sym- 
pathetic nervous system with special reference to intrinsic sensory 
neurones. Jour. Comp. Neur., vol. 24, pp. 269-281. 
Casa, S. Ramon. 1911 Histologie du systéme nerveux de l’homme et des 
vertébrés, vol. 2, p. 891. Paris, 1911. 
Cuasz, M. R., anp Ranson, 8. W. 1914 The structure of the vagus nerve. 
Jour. Comp. Neur., vol. 24, p. 31. 
Doaret, A. 8S. 1895 Zur Frage tiber den feineren Bau des sympathischen Ner- 
vensystems bei den Séiugethieren. Arch. f. mikr. Anat., vol. 46, p. 305. 
1896 Zwei Arten sympathischer Nervenzellen. Anat. Anz., 11, pp. 
679-687. 
Enrutcu 1886 Uber die Methylenblaufirbung der lebenden Nervensubstanz. 
Deutsche Med. Wochensch., Bd. XII, p. 49. 
Hormann, F. B. 1904 Die neurogene und myogene Theorie der Herzthatigkeit 
und die Funktion der inneren Herznerven. Schmidt’s Jahrb. d. ges. 
Medicin, Bd. 281, p. 118. 
Huser, G.C. 1899 A contribution on the minute anatomy of the sympathetic 
ganglia of the different classes of vertebrates. Jour. Morph., vol. 16, 
pp- 27-90. 
