

GKEAT SYMPATHETIC. 95 



presents itself, but it is never so distinct as in the vertebrata; hence 

 he deduces, and with probability, that as the sympathetic system is not 

 developed in proportion to the predominant activity of the functions 

 of organic life, but in proportion to the developement of the higher 

 division of the nervous system, its office is not to preside over the former, 

 but to bring them in relation with the latter; so that the actions of the 

 organs of vegetative life are not dependent upon it, but influenced by 

 it in accordance with the operations of the system of animal life. 



Again, the great sympathetic has been esteemed to be the visceral 

 nerve par excellence, or the one that supplies the different viscera with 

 their nervous influence, a part of its office as the nervous system of 

 involuntary functions. On examining the course of the great sympa- 

 thetic, we find many filaments proceeding from the cervical and thoracic 

 ganglions, interlacing and forming the cardiac plexus, from which the 

 nerves of the heart and great vessels arise. The same thoracic gan- 

 glions furnish a branch to each intercostal artery. A nerve of the 

 great sympathetic called the great splanchnic or visceral proceeding 

 from some of the thoracic ganglions, passes through the pillars of the 

 diaphragm into the abdomen, and terminates in the large plexus or 

 ganglion, called the semilunar ; and this by uniting with its fellow of 

 the opposite side, constitutes the still more extensive interlacing, the 

 solar plexus. From this, numerous filaments proceed, which by ac- 

 companying the coronaria ventriculi, hepatic, splenic, spermatic, renal, 

 superior and inferior mesenteric, and hypogastric arteries are distri- 

 buted to the parts supplied with blood by these arteries, the stomach, 

 liver, spleen, testes, kidneys, intestines, &c. Weber, 1 however, who 

 examined the great sympathetic in different animals, affirms, that the 

 splanchnic may not be the sole visceral nerve, but that the eighth pair 

 may share in the function. He states, that the great sympathetic is 

 less developed, the lower the animal is in the scale; whilst the eighth 

 pair is more and more developed as we descend, and at length is the 

 only visceral nerve in some of the mollusca. Sir A. Cooper's 2 experi- 

 ments satisfied him, that this nerve is essential to the digestive process; 

 but of this we shall have to speak hereafter. In the prosecution of 

 those experiments, he found, that when the great sympathetic was tied 

 on a dog, but little effect was produced: the animal's heart appeared 

 to beat more quickly and feebly than usual; but of this circumstance 

 he could not be positive, on account of the natural quickness of its 

 action. The animal was kept seven days, at which time one nerve was 

 ulcerated through, and the other nearly so, at the situation of the 

 ligatures. Another animal on which the sympathetic had been tied 

 nearly a month before, was still living when he wrote. When the 

 pneumogastric or eighth pair, the phrenic, and the great sympathetic 

 were all tied on each side, "the animal lived little more than a quarter 

 of an hour, and died of dyspnoea." 3 



These experiments would appear to show, either that the great sym- 

 pathetic is not so indispensable to the economy as has been imagined ; 



1 Anatom. Comparat. Nerv. Sympath., Lips., 1817. 



3 Guy's Hospital Reports, vol. i. p. 457, London, 1836. 3 Ibid., p. 471. 



