144 ANTHROPOLOGY. 



be carefully divided, the latter will be found equally apparent. The great 

 distinction depends on the occurrence of numerous ganglions, both on the 

 principal cords as well as on their branches; each ganglion is invested with 

 a firm capsule, which is continuous with the sheath of the afferent and effe- 

 rent nerves. This capsule is surrounded by areolar tissue and blood-vessels; 

 the latter ramify on and pierce the capsule; the internal surface of the latter 

 is vascular, and may, on the larger ganglions, be separated as a vascular 

 membrane from the external fibrous layer, and is analogous to the pia mater 

 on the cerebro-spinal axis. The mass of a ganglion is composed of a plexus 

 of nervous filaments, with a variable quantity of vesicular or greyneurine: 

 the afferent nerves divide into numerous fibrilhe, which pass in the most 

 varied directions, and re-unite most probably in different combinations, the 

 interstices being filled with capillary vessels and grey neurine. Whether 

 the efferent nerves consist of those filaments only which composed the affe- 

 rent, or whether additional fibres are added to these in the ganglion, it is, 

 in the present state of our knowledge, difficult if not impossible to deter- 

 mine. The only material difference to be observed between the structure 

 of the ganglions of the sympathetic and those of the cerebro-spinal system 

 is, that the latter appear in general to be less red and vascular, and to con- 

 tain less of the vesicular or grey neurine ; the interlacement of white fibres 

 is more obvious in them, and constitutes the gi'eater portion of each, par-, 

 ticularly of the spinal ganglions. 



PI. 138, fig. 18, upper part of the great sympathetic nerve : ', uppermost 

 cervical ganglion; "■", branches from it to the accessory nerve ; '•', junc- 

 tions with the cervical nerves ; *, branch of the vagus ; ^, upper branch of 

 the first cervical ganglion ; °, communicating threads to Jacobson's nerve ; 

 ', threads to the otic ganglion ; ', threads to the oculomotor ; \ threads to 

 the vidian nerve; ", spheno-palatine ganglion with its branches; ", pharyn- 

 geal and carotid branches of the first cervical ganglion ; '', glosso-pharyn- 

 geal nerve; ", pharyngeal plexus; ", long or superior cardiac nerve; ", a 

 cardiac nerve from the vagus ; ", middle cervical ganglion ; *°, its upper 

 branches, one of which unites with the first cervical ganglion or with the 

 main trunk, two others with the cervical nerves ; ", middle cardiac nerve ; 

 ''\ its connecting threads, with the pharyngeal branch of the tenth pair ; 

 ", inferior cervical ganglion ; "\ its connexion with the brachial plexus ; 

 ", branches passing into the vertebral canal with the vertebral artery ; 

 "', branches connecting it with the middle cervical ganglion, of which one 

 passes before, the other behind the subclavian artery ; ", lowest cervical 

 ganglion ; ", union of the tenth pair with the cardiac plexus ; ^°, plexus at 

 the arch of the aorta; ^°, plexus between the trachea and the pulmonic 

 artery; ", tracheal branches penetrating into the lungs; ^''", pulmonic 

 plexus (from the tenth pair) and the connexion with the cardiac plexus ; 

 ", anterior, ", posterior cardiac plexus; "•", two thoracic ganglions; 

 ""' "', branches to the descending aorta ; ", connexion of a thoracic ganglion 

 with an intercostal nerve ; ^'', great splanchnic nerve. Fig. 14, lower por- 

 tion of the sympathetic nerve : *■ '* ', three thoracic ganglions, with their 

 roots proceeding from the spinal nerves ; "' °, branches descending to the 

 850 



