THE NERVOUS SYSTEM. 137 



dulla of the nerves at their commencement, * in such a 

 way, as to unite very delicately with the vascular 

 cortex. f But as soon as they have quitted the brain 

 or medulla spinalis, their structure becomes peculiar, 

 different from that of all the other similar parts. They 

 form transverse folds more or less oblique and angular, 

 long since described by P. P. Mollinelli, | who not in- 

 aptly compared them to the rugae of earth-worms or 

 the rings of the aspera arteria. 



213. The nerves, especially those which are remark- 

 able, for instance, the intercostals and par vagum, are 

 here and there furnished with ganglia, or nodules of a 

 compact structure and reddish ash colour, but with 

 whose functions we are scarcely acquainted. I am in- 

 clined to believe with Zinn that they more intimately 

 unite the nervous filaments which meet in them from 

 various directions, so that each fibre passing out 

 is composed of a portion of every fibre that has en- 

 tered in. || 



Nearly the same holds good with respect to the plex- 



* Consult Pfeffingcr, De structura Nervorum. Argent. 1782. 4to. 



f- Wm. Battle, De Principiis Animalibm. p. 126. 



t Comment. Instituti Bononiens. T. iii. 1755. p. 282 sq. fig. 1,2. 



The observation of Mollinelli has been abundantly confirmed and further 

 illustrated by Felix Fontana and Al. Monro : by the latter in his work so often 

 quoted, and by the former in his treatise Sur le Venin de la Viptre. Flor. 1781. 

 4to. vol. ii. 



M<!m. de r Acad. des Sc. de Berlin. Vol. ix. 1753. 



|| Consult among others who treat professedly of the ganglia, J. Johnstone, 

 Med. Essays and Observ. Evcsham. 1795. 8vo. 



J. Gottl. Haase's Dissertation. Leipz. 1772. 4to. 



T. Caverhill, Treatise of Ganglions. Lond. 1772. 8vo. 



Ant. Scarpa, Anatom. Aimotat. L. i. de nervor. Gangliis et Plexubus 

 Mutin. 1799. 4to. 



G. Prochaska, De structura ncnnrum. Vindob. 1780. bvo. Al. Monro, 1. c. 



