428 MARTIN K. CHASE 



fibers normally present. In the nuiterial studied it was possible 

 to demonstrate more groups of unmyelinated fibers of sympa- 

 thetic origin in the thoracic vagus in the animals in which only 

 the vagtis was severed high in the neck, than in those operated 

 by division of both vagus and sympathetic trunks. It is thought 

 that this finding is the result of individual ^'ariation in the ani- 

 mals, but it is possible that the difference in operative procedure 

 has something to do with it. 



The unmyelinated character of the thoracic vagus nerve in 

 the dog is not due to the presence of fibers derived from the 

 sympathetic trunk, during the close association of the vagus 

 and sympathetic nerves in the neck. 



BIBLIOGRAPHY 



Chase and Ranson 1914 The structure of the roots, trunk and branches of 



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 Gaskell, W. H. 1886 On the structure, distribution and function of the nerves 



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1889 On the relation between the structure, function and origin of 



the cranial nerves. Jour. Phj^s., London, vol. 10, p. 153. 

 Langley, J. N. 1900 The sympathetic and other related systems of nerves. 



Schiifer's text-book of Physiology, vol. 2, p. 665. 



1903 Die Kranialen autonomen Nerven und ihre Ganglien. Ergeb. 



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Anat., vol. 12, p. 67. 



1912 The structure of the spinal ganglia and of the spinal nerves. 



Jour. Comp. Neur., vol. 22, p. 159. 



1914 The structure of the vagus nerve of man as demonstrated b}^ a 

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