256 NERVOUS SYSTEM. [SECT. 1 24. 



ganglia, and in the small ganglia upon the urinary bladder of the ' 

 bombinator, in which, as also in similar ganglia of the frog, the | 

 matter is as clear as possible. 



It is still doubtful, how the nerve-tubes arising from these dif- 

 ferent sources — the rami communicantes, ganglia of the sympa- 

 thetic cord and the peripheral ganglia — are related in their 

 distribution. Many peripheral branches anastomose with others, 

 and are then withdrawn from further investigation, as, for in- 

 stance, the nervi carotid externi and nervus caroticus internus, the 

 latter of which, containing almost solely fine fibres, with a large 

 number of Remak- fibres , I do not regard as a root in the usual 

 meaning of the word, but as a branch arising from the superior cer- 

 vical ganglion, and, perhaps, the other cervical ganglia ; further, the 

 parts of the nervi communicantes, which run towards the periphery 

 with the spinal nerves, the rami cardiaci, pulmonales, etc. Other 

 branches become so fine in the parenchyma of the organs, that it 

 is impossible to trace them for any great length. The following 

 is all that has been ascertained with respect to their final course : 

 1. Divisions of fibres occur in the trunks and terminal ramifications 

 of the sympathetic, as in the nerves of the spleen, of the Pacinian 

 bodies in the mesentery, in the nerves accompanying the vessels in 

 the mesentery of the frog, in those situated laterally on the uterus 

 of rodent animals, then those of the lungs, heart and stomach 

 of the frog and rabbit ; in those of the dura mater on the arteriae 

 meningeal, in the branches of the sympathetic of the sturgeon, in 

 the cardiac nerves of amphibia, in ' the nerves of the urinary 

 bladder of the rabbit and mouse, in those of the. peritoneum of 

 man and the mouse, in the lacrymal and salivary glands. 2. Free 

 terminations of the nerve-fibres exist, as in the so-called Pacinian 

 bodies, in the heart and upon the mesenteric vessels of the frog. 

 3. The thicker tubes of the sympathetic become at length attenuated, 

 being converted into fine tubes, as may be readily seen in the 

 rami intestinales, lienales, and hepatici, although in the interior 

 of the above-mentioned organs, these nerves may retain a few 

 larger nerve-tubes, which, however, they eventually lose. The 

 actual terminations of these nerves in the organs, in the heart, 

 lungs, stomach, intestines, kidneys, spleen, liver, uterus, etc., are 

 quite unknown ; still, from the impossibility of finding dark- 

 bordered tubes in the ultimate ramifications of these nerves, it 

 may be supposed, that they end almost everywhere in non-medul- 

 lated, embryonic fibres. In fact, I have hitherto in vain endeavoured 

 to hit upon them. 



